FIS-483 Consolidated Engineering Study Report

Marathon Petroleum Company 

Catlettsburg Refinery, KY 

Capacity Improvement Study of LPCCR 

Platformer Heater (1-44-B-1/2/3/4) 

BY 

FURNACE IMPROVEMENTS 

1600 Highway 6, Suite 480 

Sugar Land, TX 77478 

www.heatflux.com 

(281) 980-0325 

FIS Project 483 January 2019 

1

Marathon Petroleum Company, Catlettsburg Refinery, KY 

Capacity Improvement Study of LPCCR Platformer Heater (1-44-B-1/2/3/4) 

Table of Contents 

Section 1 Executive Summary ......................................... 10 

1.1 Introduction ............................................................................................ 10 

1.2 Design Observations ............................................................................. 10 

1.3 Operating Observations ........................................................................ 10 

1.4 Recommendation ................................................................................... 11 

1.5 Cost Estimation ...................................................................................... 12 

Section 2 Scope of Services & Design Basis ................. 13 

2.1 Scope of Services .................................................................................. 13 

2.2 Design Basis ........................................................................................... 14 

2.3 Feed Data ................................................................................................ 16 

2.4 Fuel Gas Characteristics ....................................................................... 20 

Section 3 System Analysis ............................................... 21 

3.1 LPCCR Platformer Heater Description ................................................. 21 

Section 4 Current Data Analysis ...................................... 36 

4.1 Analysis from Graphs ............................................................................ 36 

4.2 Current Operation Modeling .................................................................. 97 

Section 5 Recommendations ......................................... 135 

5.1 Split Flow Technology ......................................................................... 135 

5.2 Energy balance for process heat recovery in convection section .. 135 

Furnace Improvements 

Low Cost Solutions for Fired Heaters 2



5.3 New Convection Section with Split Flow Technology ...................... 136 

5.4 Proposed Convection Section Design ............................................... 137 

5.5 Effect of Charge Rate on the proposed design with split flow 

convection section ......................................................................................... 153 

5.6 Salient Features of Revamp Model ..................................................... 156 

Section 6 Cost Estimation .............................................. 159 

6.1 Basis of Cost Estimation ..................................................................... 159 

6.3 Proposed Design: New Convection Section ...................................... 159 

Section 7 Appendix ......................................................... 162 

7.1 List of P & ID’s ...................................................................................... 162 





List of Figures 

Figure 1: Naphtha Charge Rate, MBPD .................................................................................. 38 

Figure 2: Naphtha API Gravity, °API........................................................................................ 38 

Figure 3: Naphtha Charge Rate, Mlb/hr .................................................................................. 39 

Figure 4: Recycle Gas Flow Rate, MMSCFD ......................................................................... 39 

Figure 5: Recycle Gas Flow Rate, Mlb/hr ............................................................................... 40 

Figure 6: Recycle Gas / Naphtha Flow Rate Ratio ................................................................ 40 

Figure 7: Total Feed Flow Rate to Each Cell ......................................................................... 41 

Figure 8: Charge Heater Feed Inlet Temperature ................................................................. 44 

Figure 9: Charge Heater Feed Outlet Temperature .............................................................. 44 

Figure 10: Charge Heater Temperature Rise ......................................................................... 45 

Figure 11: Charge Rate × ∆T of Charge Heater .................................................................... 45 

Figure 12: Charge Heater Tube Metal Temperature ............................................................. 46 

Figure 13: Flue Gas Temperature Leaving Charge Heater ................................................. 46 

Figure 14: Excess O 2 at Charge Heater .................................................................................. 47 

Figure 15: Charge Heater Fuel Gas Flow Rate ..................................................................... 47 

Figure 16: Charge Heater Fuel Gas Pressure ....................................................................... 48 

Figure 17: Charge Heater Firing Rate (Provided by Client) ................................................. 48 

Figure 18: Charge Heater Firing Rate (from Fuel Flow Rate) ............................................. 49 

Figure 19: Charge Heater Firing Rate Comparison............................................................... 49 

Figure 20: Charge Rate × ∆T Vs Firing Rate of Charge Heater .......................................... 50 

Figure 21: Charge Heater Bridge Wall Temperature Vs Firing Rate (Provided by Client) 

....................................................................................................................................................... 50 

Figure 22: Inter Heater 1 Feed Inlet Temperature ................................................................. 54 

Figure 23: Inter Heater 1 Feed Outlet Temperature .............................................................. 54 





Figure 24: Inter Heater 1 Temperature Rise .......................................................................... 54 

Figure 25: Charge Rate × ∆T of Inter Heater 1 ...................................................................... 55 

Figure 26: Inter Heater 1 Tube Metal Temperature............................................................... 56 

Figure 27: Flue Gas Temperature Leaving Inter Heater 1 ................................................... 56 

Figure 28: Excess O 2 at Inter Heater 1 Exit ............................................................................ 57 

Figure 29: Inter Heater 1 Fuel Gas Flow Rate ....................................................................... 57 

Figure 30: Inter Heater 1 Fuel Gas Pressure ......................................................................... 58 

Figure 31: Inter Heater 1 Firing Rate (Provided by Client) ................................................... 58 

Figure 32: Inter Heater 1 Firing Rate (from Fuel Flow Rate) ............................................... 59 

Figure 33: Inter Heater 1 Firing Rate Comparison ........................................................... 59 

Figure 34: Charge Rate × ∆T Vs Firing Rate of Inter Heater 1 ............................................ 60 

Figure 35: Inter Heater 1 Bridge Wall Temperature Vs Firing Rate (Provided by Client . 60 













Figure 48: Charge Rate × ∆T Vs Firing Rate of Inter Heater 2 ............................................ 70 





Figure 49: Inter Heater 2 Bridge Wall Temperature Vs Firing Rate (Provided by Client) 70 













Figure 62: Charge Rate × ∆T Vs Firing Rate of Inter Heater 3....................................... 80 

Figure 63: Inter Heater 3 Bridge Wall Temperature Vs Firing Rate (Provided by Client) 80 

Figure 64: Steam Generation Coil Circulation (MGPM) ....................................................... 84 

Figure 65: Steam generation Coil Circulation (Mlb/hr) .......................................................... 84 

Figure 66: Flow Rate of Steam Generated ............................................................................. 85 

Figure 67: Boiler Feed Water Flow Rate (GPM) .................................................................... 85 

Figure 68: BFW Coil Inlet Temperature .................................................................................. 86 

Figure 69: BFW Coil Outlet Temperature ............................................................................... 86 

Figure 70: BFW Coil Temperature Rise .................................................................................. 87 

Figure 71: Average Flue Gas Temperature Leaving Radiant Section ............................... 87 

Figure 72: Flue Gas Temperature Leaving Convection Section ......................................... 88 

Figure 73: Flue Gas Temperature Approach .......................................................................... 88 





Figure 74: Flue Gas ΔT Across Convection ........................................................................... 89 

Figure 75: Total Firing Rate (Provided by Client) .................................................................. 90 

Figure 76: Total Firing Rate (from Fuel Flow Rate) ............................................................... 90 

Figure 77: Total Firing Rate Comparison ................................................................................ 91 

Figure 78: Flue Gas Temperature at Convection Exit Vs Total Firing Rate .............. 91 

Figure 79: Draft at Convection Entry ....................................................................................... 92 

Figure 80: Average Excess O 2 at Radiant Exit ...................................................................... 92 

Figure 81: Stack Damper Position ........................................................................................... 93 

Figure 82: Fuel Gas Molecular Weight .................................................................................... 95 

Figure 83: Fuel Gas Net Heating Value .................................................................................. 95 

Figure 84: Fuel Gas Molecular Weight Vs Fuel Heating Value ........................................... 96 

Figure 85: Bridgewall Temperature Comparison ................................................................. 156 

Figure 86: Firing Rate Comparison ........................................................................................ 157 

Figure 87: Flue Gas Convection Exit Temperature ............................................................. 158 





List of Tables 

Table 1: Existing Design Rich Case Data ........................................................... 14 

Table 2: Proposed Design Basis / Projected Operating Case ............................. 15 

Table 3: Debutanizer Data for Proposed Case ................................................... 15 

Table 4: LPCCR Feed Distillation ....................................................................... 16 

Table 5 : LPCCR Feed Composition: - Naphtha ................................................. 16 

Table 6 : Recycle Gas Composition .................................................................... 18 

Table 7: Fuel Gas Properties .............................................................................. 20 

Table 8: Rich Feed Design Case Simulation ...................................................... 27 

Table 9: List of Graphs of Feed .......................................................................... 36 

Table 10 : Analysis of Feed Operating Data ....................................................... 37 

Table 11: List of Graphs of Charge Heater ......................................................... 42 

Table 12: Analysis of Operating Data of Charge Heater ..................................... 43 

Table 13: List of Graphs of No. 1 Inter Heater .................................................... 52 

Table 14: Analysis of Operating Data of No. 1 Inter Heater ................................ 53 


Table 16: Analysis of Operating Data of No. 2 Inter Heater ................................ 63 


Table 18: Analysis of Operating Data of No.3 Inter Heater ................................. 73 

Table 19: List of Graphs of Convection Section .................................................. 82 

Table 20: Analysis of Operating Data of Convection Section .............................. 83 

Table 21 : List of Graphs of Fuel ......................................................................... 94 

Table 22: Analysis of Operating Data of Fuel ..................................................... 94 





Table 23: Simulation of DCS Case (06/25/18) .................................................... 98 

Table 24: Simulation of Maximum Firing Case (06/11/18) ................................ 107 

Table 25: Simulation of Maximum Charge Case (08/30/18) ............................. 116 

Table 26: Simulation of Average Charge Case (04/13/18) ................................ 125 

Table 27: Proposed Simulation Comparison .................................................... 140 





1.1 Introduction 

Section 1 

Executive Summary 

FIS was employed by Marathon Catlettsburg Refinery, KY to carry out a capacity 

improvement study of LPCCR Platformer Heater (1-44-B-1/2/3/4). The existing 

Platformer Heater was built in 1992. It is designed for a Naphtha charge rate of 18.2 

MBPD and recycle gas rate of 26.4 MMSCFD. It is rated for 106.3 MMBtu/hr 

process duty in radiant section. The convection section recovers waste heat of 50.5 

MMBtu/hr and generates 55,966 lb/hr of steam. 

Marathon is operating the heater at an average of 22.9 MBPD of Naphtha charge 

rate. They are fuel gas pressure limited at burners for the Platformer heater. 

Marathon is looking to revamp the heater for a Naphtha feed rate 24.5 MBPD which 

is maximum operated charge rate as per last one-year operating data and 40 

MMSCFD of Recycle Gas flowrate. They want to increase the heat duty to 250 

MMBtu/hr utilizing the permitted firing capacity of 280 MMBtu/hr (LHV). 

FIS performed a Capacity Improvement Study to evaluate the complete 

performance. FIS analyzed the existing design and current operation of the heater. 

Based on the above, FIS has developed a very economical option for increasing 

the capacity of the Platformer Heater using our patented Split Flow Technology. 

With the split flow arrangement, the proposed new convection section can provide 

44.25 MMBtu/hr of process duty. The scheme also recovers 5.12 MMBtu/hr of 

debutanizer reboiler duty and generates 53,061 lb/hr of steam. 

1.2 Design Observations 

FIS reviewed the existing design configuration of the Platformer heater. We ran 

the existing heater design simulation and the design is found to be in order. The 

simulation results closely match the process conditions, bridge wall temperature 

and steam generation in the datasheet. 

1.3 Operating Observations 

FIS analyzed daily operating data of Platformer Heater for one year provided by 

Marathon. The following observations were made regarding the current operation 

of the heater: 





Average feed flow rate to each cell is 263,190 lb/hr. 

Average firing rate is 235.22 MMBtu/hr. 

Feed inlet and outlet temperature in each cell are lower than the original design 

temperatures. Feed temperature rise in Charge Heater, inter heater 1 and Inter 

Heater 2 is higher than the design by 20°F. 

Flue gas temperature leaving the convection section is around 571°F. 

The excess O2 is in the range of 4.4%. 

The burners are operated at higher fuel gas pressure in all the radiant cells 

than the original design. The average fuel gas pressure for No.1 Interheater, 

Charge heater, No.2 Interheater and No.3 Interheater are 22.2 psig, 25.1 psig, 

22.4 psig and 28.5 psig respectively. 

Firing rate (LHV) calculated from fuel pressure almost matches the firing rate 

provided by client 

The calculated bridgewall temperature is higher than the actual. It could be that 

the radiant duty is higher than the calculated. Operating data simulation is 

indicating that the firing rates should be lower than the actual. It is also 

indicating that actual steam production is lower than calculated. We are not 

able to close the heat balance. 

1.4 Recommendation 

FIS recommends recovering process heat duty in convection section based on FIS 

Split Flow Technology. We have optimized the required process duty as well as 

the design steam generation. 

In the proposed split flow arrangement, the process flow to the heater is split 

between radiant and convection sections. About 22.4-26.5% of the charge rate 

goes to the convection section split flow coil and the balance to the radiant coils. 

FIS proposes to run split flow piping from the inlet manifolds to the new 

convection coils and then return the convection section outlet split flow piping 

back to the outlet manifold from the radiant. We recommend installing a butterfly 

control valve to control the flow to the split flow convection coils so that the outlet 

temperature is maintained the same as the radiant section. 

The new convection section will be completely prefabricated in the shop. It 

consists 15 rows of tubes arranged in two modules. The bottom module consists 

of 7 rows of tubes and the top module consist of the rest 8 rows of tubes. 

The proposed convection houses process split flow coils for all four cells in the 

bottom module. The process coils consist of bare and finned tube rows. The 

steam generation coils are arranged above the process coils. The debutanizer 

reboiler coils are sandwiched between the steam generation coils. 





This revamped design of the heater with new convection section will increase the 

charge rate capacity of the heater to 24.5 MBPD. We have sized the heater for 

the permitted firing rate of 280 MMBtu/hr (LHV). The total absorbed heat duty is 

246.5 MMBtu/hr. The total process duty is 191.7 MMBtu/hr. Debutanizer heat 

duty is 5.12 MMBtu/hr and Waste heat duty is 49.63 MMBtu/hr. 

The table below shows the comparison of existing design, maximum charge case 

and proposed design heat duties and the percentage flow through split flow coils: 

Heater 

Section 

No. 1 

Interheater 

Charge 

Heater 

No. 2 Inter 

Heater 

No. 3 Inter 

Heater 

Existing 

Design 

Case 

Maximum 

Charge case 

Proposed 

Design 

Case 

Extra Heat 

Duty 

Flow 

through 

split flow 

coils 

Heat Duty, MMBtu/hr % 

37.46 42.97 66.13 23.16 26.46 

26.12 36.20 50.08 13.88 22.41 

28.70 35.56 49.20 13.64 22.93 

13.98 19.99 26.32 6.33 24.70 

Total Duty 106.3 134.7 191.7 57.0 

The process heat duty is being increased by almost 85.4 MMBtu/hr from the 

existing design heat duty and about 57 MMBtu/hr from the current operating levels 

of 134.7 MMBtu/hr. 

1.5 Cost Estimation 

FIS has developed ±30% cost estimates for Platformer Heater(1-44-B-1/2/3/4) 

revamp. The estimated cost for the proposed recommendation is $ 9.99 Million. 

The cost includes design engineering supply and erection of the new convection 

section. It also includes split flow piping and instrumentation. 

We hope you find our report helpful and informative. We will provide you all the help 

you need in implementing these changes. We will be happy to provide you with 

follow up support, should you need further information or clarifications. 





Section 2 

Scope of Services & Design Basis 

2.1 Scope of Services 

Following scope of services is considered for the Capacity Improvement Study 

of Platformer Heater: 

2.1.1 Review & Evaluation of Existing Platformer Heater 

Review of existing design and drawings of the heater 

Study of existing burner data sheets and drawings 

Study of existing Process Flow Diagrams 

Study of existing Piping & Instrumentation Diagram 

Build a computer model of the existing heater 

Carry out the thermal simulation of the existing heater: 

2.1.2 Current Operation Analysis 

Obtain plant operating data from Marathon Catlettsburg Refinery for the 

past 3 years 

Arrange, analyze & trend operating data 

Select three sets of data corresponding to minimum, average and 

maximum operating conditions to identify the critical operating parameters 

for each data 

Simulate the performance of the heater at these operating conditions 

Check existing burner performance at current conditions 

Remark and conclusion of the current condition of the heater 

2.1.3 Proposed Options 

Evaluate Split Flow Technology and develop options to increase the 

heater capacity 

Modeling the heater at projected operating conditions 

Develop preliminary specifications of the modifications- radiant section, 

convection section, stack, piping 

Identify modifications in the heater 

Estimate ± 30% cost estimate of the proposed modification 

2.1.4 Exclusions 

Presently, our scope does not include the engineering / man hours for the 

following: 





Detailed Design Engineering of proposed modifications 

Any Mechanical / Structural / Civil design and calculations 

Any Piping, Instrumentation and electrical design and calculations. 

Any other activity not specifically mentioned in the scope of service 

2.2 Design Basis 

The following data from the heater datasheet is used for evaluating the existing 

design case of the Platformer heater: 

Table 1: Existing Design Rich Case Data 

Parameters 

Unit 

Charge 

Heater 

Inter 

Heater 1 

Inter 

Heater 2 

Inter 

Heater 3 

Process Heat Duty MMBtu/hr 26.12 37.46 28.7 13.98 

Naphtha Charge 

Rate (Calculated) 

Recycle Gas Flow 

Rate (Calculated) 

MBPD 18.2 

MMSCFD 26.4 

Total Feed Flow Rate lb/hr 211,731 

Inlet Temperature °F 866 801 852 934 

Outlet Temperature °F 1,010 1,010 1,010 1,010 

Temperature Rise °F 144 209 158 76 

Inlet Pressure psig 77 71.8 68.2 63.0 

Outlet Pressure psig 75.8 69.8 66.2 61.3 

Coil Pressure Drop psi 1.2 2.0 2.0 1.7 

Waste Heat Duty MMBtu/hr 50.5 

Firing Rate MMBtu/hr 177.51 





FIS considered 280 MMBtu/hr (LHV) as the permitted firing rate for the proposed 

design basis, based on the discussion with Marathon. The proposed design basis 

is as follows: 

Table 2: Proposed Design Basis / Projected Operating Case 

Parameters 

Unit 

Charge 

Heater 

Inter 

Heater 1 

Inter 

Heater 2 

Inter 

Heater 3 

Process Heat Duty MMBtu/hr 53.4 60.5 48.6 29.5 


Rate 

Recycle Gas Flow 

Rate 

MBPD 24.5 

MMSCFD 40.0 

Total Feed Flow Rate lb/hr 288,160 

Inlet Temperature °F 741 728.7 795.9 847.1 

Outlet Temperature °F 953 988.7 990.0 954.0 

Temperature Rise °F 212 260 194.1 106.9 

Coil ΔP psi 1.2 2.0 2.0 1.7 

Debutanizer Duty MMBtu/hr 5.0 

Waste Heat Duty MMBtu/hr 53.0 

Firing Rate MMBtu/hr 280.0 

Table 3: Debutanizer Data for Proposed Case 

Parameters Unit Value 

Feed Flow Rate (Calculated) lb/hr 93,327 

Feed inlet temperature °F 504 





2.3 Feed Data 

Table 4: LPCCR Feed Distillation 

Distillation % 

DCS Case 

06/25/18 

Max. 

Charge 

08/30/18 

Avg. 

Charge 

04/13/18 

Max. 

Firing 

06/11/18 

Avg. 

Firing 

03/17/18 

°F IBP 136 139 136 136 140 

°F 10% 157 189 156 158 188 

°F 20% 192 198 191 194 197 

°F 30% 203 209 200 206 208 

°F 40% 215 219 209 217 218 

°F 50% 230 240 221 231 231 

°F 60% 252 258 244 252 247 

°F 70% 272 280 261 270 260 

°F 80% 296 299 284 290 281 

°F 90% 335 339 319 324 308 

FBP 384 408 366 371 358 

Table 5 : LPCCR Feed Composition: - Naphtha 

Compositi 

on, % 

DCS Case 

06/25/18 

Max 

Charge 

08/30/18 

Average 

Charge 

04/13/18 

Maximum 

Firing 

06/11/18 

Average 

Firing 

03/17/18 

C6 P 6.03 4.30 8.04 6.15 7.02 

C7 P 8.60 8.42 7.95 8.63 9.05 

C8 P 6.54 6.40 5.86 6.92 6.92 





C9 P 4.44 4.14 4.08 4.61 4.25 

C10 P 2.38 2.63 2.26 2.39 1.98 

C11+ P 0.34 0.45 0.09 0.16 0.05 

C6 iso P 4.67 2.79 6.22 4.72 4.24 

C7 iso P 10.39 9.10 11.1 10.2 12.0 

C8 iso P 10.6 11.0 9.77 11.1 10.9 

C9 iso P 5.9 7.6 5.4 5.9 6.3 

C10 iso P 0.77 4.98 0.71 0.80 0.70 

C11+ iso P 0.84 1.21 0.01 0.84 0.01 

C6 A 0.72 0.47 0.98 0.74 0.78 

C8 A 3.20 2.65 3.38 3.32 3.28 

C9 A 0.52 2.42 0.15 0.51 0.13 

C10+ A 0.0 1.10 0.43 0.0 0.38 

C5 N 0.26 0.08 0.36 0.24 0.12 

C6 N 2.86 1.87 7.12 2.68 6.15 

C7 N 14.59 10.06 14.25 13.89 14.02 

C8 N 8.16 7.54 7.60 8.22 8.07 

C9 N 2.22 2.83 2.37 2.32 2.18 

C10+ N 0.0 1.17 0.01 0.01 0.00 

C6 O 0.54 0.32 0.72 0.53 0.45 

C7 O 3.75 2.42 0.0 3.54 0.0 





C8 O 0.16 0.22 0.17 0.18 0.18 

C9 O 0.54 1.22 0.56 0.57 0.51 

C10 O 0.0 0.96 0.01 0.00 0.00 

C7-C11 

Naptheno 

0.26 0.41 0.20 0.24 0.18 

C10 Indane 0.44 0.16 0.0 0.36 0.0 

Total 

Paraffins 

Total 

isoParaffins 

Total 

Aromatics 

Total 

Napthenes 

Total 

Olefins 

Total 

Unknowns 

Recycle 

Gas 

Information 

Rate, 

MMSCFD 

Molecular 

Weight 

28.49 26.44 28.33 28.95 29.31 

33.22 36.70 33.27 33.61 34.17 

4.89 6.91 4.98 4.93 4.61 

28.09 23.61 31.71 27.35 30.55 

5.26 5.61 1.67 5.08 1.33 

0.05 0.72 0.03 0.08 0.03 

Table 6 : Recycle Gas Composition 

DCS Case 

(06/25/18) 

Composition, mol% 

Max 

Charge 

(08/30/18) 

Avg Charge 

(04/13/18) 

Max Firing 

(06/11/18) 

Avg Firing 

(03/17/18) 

36.0 32.0 36.0 35.0 26.8 

5.41 

H2 85.3 90.2 77.2 85.3 81.5 

C1-C5 0.01 0.00 0.01 0.02 0.00 

2,2-DMC4 0.09 0.03 0.12 0.09 0.04 

CyC5 0.26 0.08 0.36 0.23 0.12 





2,3-DMC4 0.34 0.34 0.34 0.34 0.34 

2MC5 2.27 1.33 3.02 2.25 1.91 

3MC5 1.94 1.23 2.60 2.02 1.99 

nC6 6.03 4.30 8.04 6.15 7.02 

2,2-DMC5 0.19 0.20 0.18 0.17 0.20 

MCyC5 2.87 1.87 3.73 2.68 3.11 

Benzene 0.72 0.47 0.98 0.74 0.78 

CyC6 0.00 0.00 3.39 0.00 3.03 





2.4 Fuel Gas Characteristics 

The following fuel gas design composition from datasheet is used for the existing 

design, operating and proposed design simulations. 

Table 7: Fuel Gas Properties 

Parameters 

Units 

Refinery Gas 

Design 

Alternate 

Specific Gravity at 60°F - 0.68 0.60 

Heat of Combustion (LHV) Btu/Scf 1,120 1,005 

Fuel temperature at burner F 100 100 

Components 

H2 % 39.33 46.70 

CH4 % 18.41 22.60 

C2H6 % 24.34 14.10 

C3H6 % 1.21 2.30 

C3H8 % 12.58 7.80 

I-C4H10 % 1.31 2.00 

n-C4H10 % 1.61 2.00 

i-C5H12 % 1.21 1.25 

n-C5H12 % 0 1.25 

Total % 100 100 





Section 3 

System Analysis 

3.1 LPCCR Platformer Heater Description 

The CCR Platformer heater (1-44-B-1/2/3/4) is a four-cell box type with Vertical 

Arbor (“U”) coils. The Platformer heater has a common convection section and a 

self-supported & top mounted stack. The heater was originally built and installed 

in 1992. The heater operates under natural draft. 

The Platformer heater radiant box 

consists of 4 cells; Charge heater, No. 1 

Interheater, No. 2 Interheater and No. 3 

Interheater. The radiant section of the 

heater is used to heat process service 

and the convection section is used for 

waste heat recovery. The total absorbed 

duty of the heater is 156.76 MMBtu/hr. 

The total process duty in the radiant 

section is 106.26 MMBtu/hr and the 

waste heat duty in the convection is 50.5 

MMBtu/hr. 

The heater is designed for gas firing and 

is operated at 15% excess air. The firing 

rate of the heater is 177.51 MM Btu/hr 

(LHV). The net thermal efficiency of the 

heater is 88.3% (based on LHV) 

considering 2% radiation heat loss. 

3.1.1 Radiant Section 

The process feed to the radiant section is a mixture of Naphtha and Recycle Gas. 

The flue gas temperature leaving the radiant section is 1,500ºF. 

Charge Heater (1-44-B-1) 

The Charge heater is designed for a 26.12 MMBtu/hr heat duty. It has a normal 

duty of 23.75 MMBtu/hr. This cell is designed to heat 211,731 lb/hr of feed from 

866ºF to 1,010ºF. The feed enters at a pressure of 77 psig and leaves at 75.8 psig. 

The calculated coil pressure drop is 1.2 psi. The process fluid mass velocity is 23.8 

lb/sec.ft 2 . The average radiant heat flux is 9,075 Btu/hr.ft 2 and the maximum 





radiant heat flux is 12,700 Btu/hr.ft 2 . The radiant tubes have a maximum metal 

temperature of 1,125°F. 

The Charge heater has 41.9 ft high, 38.14 ft long and 17.94 ft wide inside insulation 

dimensions. It consists of 28 inverted arbor coils arranged in 28 passes. The coils 

are 4” NPS x Sch 40. The coils are made of A335 Gr P9 material. The effective 

length of the coil is 87.3 ft. The coils are placed at a center to center spacing of 

1.27 ft. The radiant heat transfer area is 2,879 ft 2 . 

No.1 Interheater (1-44-B-2) 

The No.1 Interheater is designed for 37.46 MMBtu/hr duty. This cell is designed to 

heat 211,731 lb/hr of feed from 801ºF to 1,010ºF. The feed enters at a pressure of 

71.8 psig and leaves at 69.8 psig. The calculated coil pressure drop is 2 psi. The 

process fluid mass velocity is 23.8 lb/sec.ft 2 . The average radiant heat flux is 

10,065 Btu/hr.ft 2 and the maximum radiant heat flux is 14,090 Btu/hr.ft 2 . The 

radiant tubes have a maximum metal temperature of 1,130°F. 

The No.1 Interheater has 54.47 ft high, 38.14 ft long and 15.05 ft wide inside 

insulation dimensions. It consists of 28 inverted arbor coils arranged in 28 passes. 

The coils are 4” NPS x Sch 40. The coils are made of A335 Gr P9 material. The 

effective length of the coil is 112.85 ft. The coils are placed at a center to center 

spacing of 1.27 ft. The radiant heat transfer area is 3,723 ft 2 . 




68.2 psig and leaves at 66.2 psig. The calculated coil pressure drop is 2 psi. The 

process fluid mass velocity is 23.8 lb/sec.ft 2 . The average radiant heat flux is 9,970 

Btu/hr.ft 2 and the maximum radiant heat flux is 13,960 Btu/hr.ft 2 . The radiant tubes 

have a maximum metal temperature of 1,125°F. 









63 psig and leaves at 61.3 psig. The calculated coil pressure drop is 1.7 psi. The 





process fluid mass velocity is 23.8 lb/sec.ft 2 . The average radiant heat flux is 7,605 

Btu/hr.ft 2 and the maximum radiant heat flux is 10,650 Btu/hr.ft 2 . The radiant tubes 

have a maximum metal temperature of 1,100°F. 






The tubes in all radiant cells are provided with inlet and outlet manifolds at the top. 

The radiant section manifolds are supported on spring hangers. All the manifolds 

are 24” NPS size, are made of A335 Gr P11 material. 

The radiant floor is lined with 8” thk. Kaolite 2200. Radiant section shielded walls 

are lined with 6” thk. Kaolite 2200. The exposed radiant walls below burner level 

are lined with 8” thk. Kaolite 2200 and above burner level are lined with 6” thk. 

Kaolite 2200. The radiant arch is lined with 6” thk. Kaolite 2200. 

Ducts Connecting Radiant and Convection Sections 

Flue gas from radiant section enters the convection section through 4 ducts. All 

the four radiant cells have an opening at the center. The offtake ducts are lined 

with 6” thk. Kaolite 2200 refractory. 

Burners 

The radiant section is fired with 30 natural draft fuel gas burners. The burners are 

John Zink Ultra Low NOx PNDR-18M/20M type and are installed at the end walls 

for horizontal firing. The burners are designed for fuel gas pressure of 20 psig and 

15% excess air. The burners are arranged for the single firing of the coils in all the 

cells. Each burner has a manually ignited pilot with a flame retention head. 

The Charge heater consists of 8 burners with 4 burners on each end wall. The 

burners have a design heat release of 7.81 MM Btu/hr. The normal heat release 

per burner is 6.25 MM Btu/hr. The turndown ratio of burners is 3:1. The draft loss 

across the burners varies from 0.32-0.45 in WC at design heat release and excess 

air at 70°F. The burners are spaced at a center to center distance of 4.5 ft. The 

distance between the burner centerline to tube centerline is 5.5 ft. 

The No.1 Inter heater consists of 10 burners with 5 burners on each end wall. The 


per burner is 6.25 MM Btu/hr. The turndown ratio of burners is 3:1. The draft at 

burners varies from 0.39-0.57 in WC at design heat release and excess air at 70°F. 





The burners are spaced at a center to center distance of 4.5 ft. The distance 

between the burner centerline to tube centerline is 6 ft. 



per burner is 6.25 MM Btu/hr. The turndown ratio of burners is 3:1. The draft at 

burners varies from 0.32-0.45 in WC at design heat release and excess air at 70°F. 

The burners are spaced at a center to center distance of 4.5 ft. The distance 

between the burner centerline to tube centerline is 5.5 ft. 


burners have a design heat release of 7 MM Btu/hr. The turndown ratio of burners 

is 3:1. The draft at burners varies from 0.26-0.30 in WC at design heat release and 

excess air at 70°F. The burners are spaced at a center to center distance of 4.5 ft. 

The distance between the burner centerline to tube centerline is 5 ft. 

3.1.2 Convection Section 

The convection section is 8.33 ft wide, 56 ft long and 14.5 ft high inside insulation 

dimensions. The convection section is used for steam generation and BFW 

services. The total waste heat recovery duty in the convection is 50.5 MMBtu/hr. 

The hot flue gases leave the convection section at 448ºF. 

Convection Section 





Steam Generator 

The Steam Generator (SG) is designed for a duty of 43.95 MMBtu/hr. Saturated 

water flowrate of 574,227 lb/hr enters at 463°F and 510 psig. The SG coils are 

used to generate 55,986 lb/hr of steam at 465 psig. The calculated pressure drop 

is 45 psi. The fluid mass velocity through the SG coil is 249.7 lb/sec.ft 2 . The finned 

tubes have a maximum tip temperature of 590°F. The average convective heat flux 

(Based on bare outside surface) is 6,940 Btu/hr.ft 2 . 

The steam generator has 36 bare tubes and 60 finned tubes. The tubes are 

arranged in concurrent manner. All the tubes are 4” NPS, Sch.80 and made of 

A106 Gr B material. The tubes are arranged in 8 rows and 12 tubes per row. The 

effective length of the tube is 56 ft. The tubes are arranged in 8 passes and placed 

at 8” x 8” triangular pitch. The finned tubes are made of CS material with 0.875” 

height, 0.105” thick and 4 FPI fin configuration. The total heat transfer area is 2,375 

ft 2 (bare) + 37,700 ft 2 (finned). 

Boiler Feed Water 

The Boiler Feed Water (BFW) coils are placed at the top of convection section. It 

is designed for a duty of 6.55 MMBtu/hr. It is used to heat 70,918 lb/hr of water 

from a temperature of 300ºF to 385ºF. The inlet and outlet pressures are 470 psig 

and 465 psig respectively. The calculated pressure drop is 5 psi. The fluid mass 

velocity through the BFW coil is 123.4 lb/sec.ft 2 . The finned tubes have a maximum 

tip temperature of 415°F. The average convective heat flux (Based on bare outside 

surface) is 2,758 Btu/hr.ft 2 . 

The BFW coils consists of 36 finned tubes. The tubes are arranged in 

countercurrent manner. All the tubes are 4” NPS, Sch. 80 and made of SA 106 Gr 

B material. The tubes are arranged in 3 rows and 12 tubes per row. The effective 

length of the tube is 56 ft. The tubes are arranged in 2 passes and placed at 8” x 

8” triangular pitch. The finned tubes are made of CS material with 0.875” height, 

0.105” thick and 4 FPI fin configuration. The total heat transfer area is 22,620 ft 2 

(finned). 

The convection casing is made of 3/16” thk. CS material. It is lined with a single 

layer of 5” thk. Kaolite 2200. The end tube sheets of the convection section are 

made of ½” thk. CS material and is lined with 4” thk. Kaolite 2200. The header 

boxes are made of 3/16” thk. CS material and is lined with 2” thk. Insulating 

concrete refractory. 





3.1.3 Offtake Ducts and Stack 

The flue gas leaving the convection section enters the 

stack through two offtake ducts and is discharged into 

the atmosphere. Each offtake duct has a cross-section 

of 9.14 ft x 5.47 ft. The flue gas velocity in the offtake 

duct is 11.3 ft/s. The breaching is lined with 3” thk. 

Kaolite 2200 and offtake ducts are lined with 2” thk. 

Kaolite 2200. 

The stack is located at the top of the convection section 

and is self-supported. The length of the stack is 120 ft 

and the inside insulation diameter is 11.21 ft. Top of 

stack elevation is 213 ft. The stack is provided with a 

multi-blade damper with pneumatic actuator to control 

the draft. The damper blade and shaft are made up of 

SS-304 material. The stack is lined with 2” thk. Kaolite 

2200. The flue gas duct from the adjacent Debutanizer 

Reboiler connects the Platformer heater stack 5 ft 

above the stack damper. The debutanizer flue gas duct 

diameter is 2’ -7”. 

Refer to FIS-483-CIS-1001 (Sheets 1 and 2 of 2) for Existing Design Coil and 

Insulation Summary. 

Refer to FIS-483-PFD-1001 for Existing Design Process Flow Diagram. 

3.1.4 Basis for Existing Design Simulation 

Process data for the Platformer Heater is taken from heater data sheet. 

Mechanical Data is taken from heater datasheet and General Arrangement 

Drawings. 

The design case simulation is performed at fixed exit condition. 

We have considered an emissivity of 1.0 for the radiant tubes as they are 

coated with ceramic. 





Table 8: Rich Feed Design Case Simulation 

Parameter Unit Datasheet 

Simulation 

Output 

Total Heat Duty MMBtu/hr 156.8 158.9 

Process Heat Duty 

(Hydrocarbon) 

MMBtu/hr 106.3 105.6 

Naphtha Flowrate MBPD - 18.2 

Recycle Gas Flowrate MMSCFD - 26.4 

Total Feed Flowrate Lb/hr 211,731 211,731 

Waste Heat Duty (Steam) MMBtu/hr 50.50 53.36 

Radiant Section 

Radiant Heat Duty MMBtu/hr 106.3 105.6 

No. 1 Inter Heater (1-44-B-2) 

Heat Duty MMBtu/hr 37.46 37.49 

Heat Duty % 23.89 23.59 

Charge Flow Rate Lb/hr 211,731 211,731 

Inlet Temperature °F 801.0 807.5 

Inlet Pressure psig 71.8 71.9 

Outlet Temperature °F 1,010 1,010 

Outlet Pressure psig 69.8 69.8 

Coil Pressure Drop psi 2.0 2.1 

Radiant Heat Transfer Area ft 2 3,722 3,723 






Average Radiant Section Heat 

Flux 

Simulation 

Output 

Btu/hr/ft 2 10,064 10,070 

Max Rad. Section Heat Flux Btu/hr/ft 2 14,090 18,778 

Fluid Mass Velocity lb/sec/ft 2 - 23.8 

Bridge Wall Temperature °F 1,500 1,452 

Maximum Inside Film 

Temperature 

Maximum Tube Metal 

Temperature 

°F - 1,113 

°F 1,130 1,134 

Volumetric Heat Release Btu/hr/ft 3 - 2,287 



Heat Duty % 16.66 16.44 









Flux 

Btu/hr/ft 2 9,075 9,073 







Simulation 

Output 




Temperature 


Temperature 

°F - 1,131 

°F 1,125 1,154 


No.2 Inter heater (1-44-B-3) 


Heat Duty % 18.31 18.10 

Charge Flow Ra Lb/hr 211,731 211,731 







Average Rad. Section Heat Flux Btu/hr/ft 2 9,970 9,990 









Temperature 


Temperature 


Simulation 

Output 

°F - 1,122 

°F 1,125 1,148 




Heat Duty % 8.92 8.32 









Flux 

Btu/hr/ft 2 7,605 7,193 





Temperature 


Temperature 

°F - 1,076 

°F 1,100 1,092 






Simulation 

Output 



Total Convection Heat Duty MMBtu/hr 50.50 53.36 

Flue Gas Temp. Entering 


°F 1,500 1,491 

Steam Generation Coils 


Heat Duty % 28.03 29.30 

Circulation Flow Rate lb/hr 574,227 574,227 

Inlet Temperature °F 463.0 456 


Outlet Temperature °F 463.0 462.7 

Outlet Pressure psig 465 465.0 

Coil Pressure Drop Psi 45.0 45.1 

Steam Generation Flow Rate lb/hr 55,966 57,049 

Heat Transfer Area (Bare) Ft 2 2,375 2,375 

Heat Transfer Area (Finned) Ft 2 37,700 37,702 

Average SG Coil Section Heat 

Flux (BOS) 

Btu/hr/Ft 2 6,939 7,351 

Fluid Mass Velocity lb/s/Ft 2 - 249.7 

Flue Gas Mass Velocity lb/s/Ft 2 0.258 0.300 

Flue Gas Pressure Drop in WC - 0.076 

Flue Gas Temperature Leaving 

SG Coil Section 

°F - 555 






Outside Heat Transfer Fin 

Efficiency Factor 

Simulation 

Output 

- - - 

Maximum Fin Tip Temperature °F 590 481.5 

Boiler Feed Water Coils 


Heat Duty % 4.19 4.28 

Flow Rate Lb/hr 70,918 70,918 


Inlet Pressure Psig 470 470 

Outlet Temperature °F 385.0 391.6 

Outlet Pressure Psig 465.0 467.9 

Coil Pressure Drop Psi 5.0 2.1 

Heat Transfer Area (Finned) Ft 2 22,620 22,621 

Average BFW Coil Section Heat 

Flux (BOS) 

Btu/hr/Ft 2 2,758 2,863 

Fluid Mass Velocity Lb/s/Ft 2 - 123.4 

Flue Gas Mass Velocity Lb/s/Ft 2 0.258 0.300 

Outside Heat Transfer Fin 


- - - 

Flue Gas Pressure Drop in WC - 0.027 

Flue Gas Temperature Leaving 

BFW Coil Section 

°F 448 407 

Maximum Fin Tip Temperature °F 415 415 

Combustion 

Fuel Gas Heating Value (LHV) Btu/Scf 1,120 1,118 

Total Fuel Gas Flow Rate Lb/hr - 8,248 






Simulation 

Output 

Total Combustion Air Flow Rate Lb/hr - 159,224 

Combustion Air Temperature °F 60 60 

Total Flue Gas Flow Rate Lb/hr - 167,472 

Total Firing Rate MMBtu/hr 177.5 178.0 

Heat Loss % 2 2 

Thermal Efficiency % 88.3 89.3 


Fuel Gas Flow Rate Lb/hr - 2,873 

Combustion Air Flow Rate Lb/hr - 55,460 

Flue Gas Flow Rate Lb/hr - 58,333 

Firing Rate MMBtu/hr - 62.0 

Excess O2 % 3.00 3.00 

Excess Air % 15.0 15.0 






Excess O2 % 3.00 3.00 

Excess Air % 15.0 15.0 








Simulation 

Output 




Excess O2 % 3.00 3.00 

Excess Air % 15.0 15.0 


Fuel Gas Flow Rate Lb/hr - 996 




Excess O2 % 3.00 3.00 

Excess Air % 15.0 15.0 

3.1.5 Observations of Existing Design 

The heat absorption in the radiant section is increased with high tube 

emissivity. 

We are almost matching all the terminal conditions with the datasheet. 

We are almost matching the bridge wall temperature with the datasheet. 

Convection section flue gas exit temperature is 41°F lesser than the 

datasheet. 

The amount of steam generation is almost matching with the datasheet 

value. 





3.1.6 Existing Heater Energy Balance 

The below table shows the energy balance across the radiant and convection 

section: 

Table 9: Existing Heater Energy Balance 


Parameter 

Unit 

Charge 

Heater 

No. 1 

Interheater 

No. 2 

Interheater 

No. 3 

Interheater 

Firing Rate MMBtu/hr 44.5 62.0 50.0 21.5 

Bridgewall 

temperature 

°F 1,512 1,452 1,552 1,418 

Flue Gas Enthalpy Btu/lb 415.3 396.6 427.8 386.1 

Flue Gas Flowrate Lb/hr 41,868 58,333 47,043 20,228 

Radiant Heat Loss % 2.0 2.0 2.0 2.0 

Radiant Duty MMBtu/hr 26.20 37.63 28.88 13.26 

Total Radiant Duty MMBtu/hr 105.97 


Flue Gas Conv. Inlet 

Temperature 

Flue Gas Conv. Outlet 

Temperature 

Enthalpy of Flue Gas 

at Conv. Inlet 

Enthalpy of Flue Gas 

at Conv. Outlet 

Total Flue Gas 

Flowrate 

°F 1,491 

°F 406.9 

Btu/lb 408.8 

Btu/lb 92.27 

Lb/hr 167,472 

Total Convection Duty MMBtu/hr 53.01 

Steam Generated lb/hr 56,675 





Section 4 

Current Data Analysis 

Marathon has provided operating data of 1 year for the Platformer heater from 

2 nd November 2017 to 1 st November 2018. FIS carried out a detailed analysis of 

the data and the data is plotted with respect to time to observe the operating 

trend and variation with respect to the design value. 

4.1 Analysis from Graphs 

4.1.1 Feed Flowrate Analysis 

Table 10: List of Graphs of Feed 

Figure No. Parameters Tag no. 

Figure 1 Naphtha Charge Rate FC1 

Figure 2 Naphtha API Gravity 338033.A 

Figure 3 Naphtha Charge Rate Calculated 

Figure 4 Recycle gas Flow Rate FC2 

Figure 5 Recycle gas Flow Rate Calculated 

Figure 6 

Recycle Gas / Naphtha 

Flowrate Ratio 

Calculated 

Figure 7 Total Feed Flowrate Calculated 





Table 11 : Analysis of Feed Operating Data 

Description Units Max. Avg. Design 


Rate 

MBPD 24.5 22.9 18.2 

Naphtha API Gravity °API 61.1 59.6 60 


Rate 

Recycle gas Flow 

Rate 

Recycle gas Flow 

Rate 

Recycle Gas/Naphtha 

Flowrate Ratio 

Mlb /hr 267 244 196 

MMSCFD 38.5 32.3 26.4 

Mlb /hr 22.9 19.1 15.7 

lb/lb 0.34 0.08 0.08 

Total Feed Flowrate Mlb / hr 287.4 263.2 211.7 





FLOWRATE, MBPD 

27 

25 

23 

21 

19 

Figure 1: Naphtha Charge Rate, MBPD 

AVERAGE=22.9 MBPD 

DESIGN=18.2 MBPD 

(FC1) 

17 

2-Nov-17 13-Jan-18 27-Mar-18 8-Jun-18 

TIME 

20-Aug-18 1-Nov-18 

Figure 2: Naphtha API Gravity, °API 





FLOWRATE, MLB/HR 

280 

260 

240 

220 

Figure 3: Naphtha Charge Rate, Mlb/hr 

AVERAGE=244.06 MLB/HR 

DESIGN =196.3 MLB/HR 

(CALCULATED) 

200 

180 

2-Nov-17 13-Jan-18 27-Mar-18 8-Jun-18 

TIME 

20-Aug-18 1-Nov-18 

Figure 4: Recycle Gas Flow Rate, MMSCFD 





Figure 5: Recycle Gas Flow Rate, Mlb/hr 

FLOWRATE, MLB/HR 

24 

22 

20 

18 

16 

AVERAGE=19.1 MLB/HR 

DESIGN=15.7 MLB/HR 

(CALCULATED) 

14 

2-Nov-17 13-Jan-18 27-Mar-18 8-Jun-18 

TIME 

20-Aug-18 1-Nov-18 

Note: Recycle Gas molecular weight of 5.41 lb/lbmol (provided for only one day in 

operating data) was considered in this calculation. 

Figure 6: Recycle Gas / Naphtha Flow Rate Ratio 

0.10 

AVERAGE=0.08 LB/LB 

(CALCULATED) 

FLOW RATE RATIO, LB/LB 

0.09 

0.08 

0.07 

0.06 

0.05 

2-Nov-17 13-Jan-18 27-Mar-18 8-Jun-18 

TIME 

20-Aug-18 1-Nov-18 





Figure 7: Total Feed Flow Rate to Each Cell 

Observations on Feed Flowrate Graphs: 

Operating process feed flow rate is 24.3% higher than the design. The 

average operating feed flow rate is 263,190 lb/hr and the design feed 

flowrate is 211,731 lb/hr. 





4.1.2 Charge Heater Analysis: 

Table 12: List of Graphs of Charge Heater 

Figure No. Parameters Tag No. 

Figure 8 Inlet Temperature TI3 

Figure 9 Outlet Temperature TC252 

Figure 10 Temperature Rise Calculated 

Figure 11 Charge Rate X ∆T Calculated 

Figure 12 Tube Metal Temperature TI552 

Figure 13 Bridge Wall Temperature TI204 

Figure 14 Bridge wall O 2 AI11C 

Figure 15 Fuel Gas Flow Rate FC53 

Figure 16 Fuel Gas Pressure PI169 

Figure 17 Firing Rate B1BTU.C 

Figure 18 

Firing Rate Based on 

Fuel Flow Rate 

Calculated 

Figure 19 Firing Rate Comparison - 

Figure 20 

Figure 21 

Charge Rate X ∆T Vs 

Firing Rate 

Bridge Wall Temperature 

Vs Firing Rate 

- 

- 





Table 13: Analysis of Operating Data of Charge Heater 

Description Units Maximum Average Design 

Inlet Temperature ºF 783 751 866 

Outlet Temperature ºF 946 911 1,010 

Temperature Rise ºF 175 161 144 

Charge Rate X ∆T Mlb°F/hr 48,212 42,120 30,489 

Tube Metal 

Temperature 

Bridge Wall 

Temperature 

ºF 1,089 1,017 1,125 

ºF 1,453 1,392 1,500 

Bridge wall O2 % 7.90 4.49 3.00 

Fuel Gas Flow Rate MMSCFD 1.58 1.44 0.96 

Fuel Pressure Psig 26.97 25.06 9.8 

Firing Rate MMBtu/hr 76.02 66.76 44.5 




Fuel Gas Pressure 

MMBtu/hr 83.52 60.53 44.5 

MMBtu/hr 76.3 65.37 44.5 





Figure 8: Charge Heater Feed Inlet Temperature 

Figure 9: Charge Heater Feed Outlet Temperature 





Figure 10: Charge Heater Temperature Rise 

Figure 11: Charge Rate × ∆T of Charge Heater 





Figure 12: Charge Heater Tube Metal Temperature 

Figure 13: Flue Gas Temperature Leaving Charge Heater 





Figure 14: Excess O2 at Charge Heater 

Figure 15: Charge Heater Fuel Gas Flow Rate 

Note: The values in operating data is divided by 1,000 





Figure 16: Charge Heater Fuel Gas Pressure 

Figure 17: Charge Heater Firing Rate (Provided by Client) 





Figure 18: Charge Heater Firing Rate (from Fuel Flow Rate) 

Figure 19: Charge Heater Firing Rate Comparison 





Figure 20: Charge Rate × ∆T Vs Firing Rate of Charge Heater 

Figure 21: Charge Heater Bridge Wall Temperature Vs Firing Rate (Provided 

by Client) 





Observations on Charge Heater Graphs: 

The heater is operating at 115 °F lower process feed inlet temperature 

than the design. The average operating process feed inlet temperature is 

751°F and the design process feed inlet temperature is 866°F. 

The process feed outlet temperature is lower than the design. The 

average operating process feed outlet temperature is 911°F and the 

design process feed outlet temperature is 1,010°F. 

Average operating process feed temperature rise is higher than the design 

value by 20°F. 

Burners are often operated at a higher fuel gas pressure than the design. 

The average operating fuel gas pressure is 25.06 psig which is higher than 

the design value of 9.8 psig. 

in current operation, average excess O2 at arch is 4.49%, which is higher 

than the design value of 3%. 

Bridge wall temperature is lesser than the design. The average bridge wall 

temperature is 1,392°F and the design bridge wall temperature is 1,500°F. 





4.1.3 No. 1 Inter Heater Analysis: 

Table 14: List of Graphs of No. 1 Inter Heater 








Figure 28 Bridge wall O2 AI11D 




Figure 32 Firing Rate Based on Fuel Flow Rate Calculated 


Figure 34 Charge Rate X ∆T Vs Firing Rate - 

Figure 35 Bridge Wall Temperature Vs Firing Rate - 





Table 15: Analysis of Operating Data of No. 1 Inter Heater 

Description Units Max. Avg Design 




Charge Rate X ∆T Mlb°F/hr 70,745 47,940 44,252 

Tube Metal 

Temperature 

Bridge Wall 

Temperature 

ºF 1,040 997.8 1,130 

ºF 1,393 1,356 1,500 

Bridge wall O2 % 7.58 4.38 3.00 








MMBtu/hr 96.46 69.94 62.0 

MMBtu/hr 86.1 74.45 62.0 





Figure 22: Inter Heater 1 Feed Inlet Temperature 

Figure 23: Inter Heater 1 Feed Outlet Temperature 





Figure 24: Inter Heater 1 Temperature Rise 

Figure 25: Charge Rate × ∆T of Inter Heater 1 





Figure 26: Inter Heater 1 Tube Metal Temperature 

Figure 27: Flue Gas Temperature Leaving Inter Heater 1 





Figure 28: Excess O2 at Inter Heater 1 Exit 

Figure 29: Inter Heater 1 Fuel Gas Flow Rate 





Figure 30: Inter Heater 1 Fuel Gas Pressure 

Figure 31: Inter Heater 1 Firing Rate (Provided by Client) 





Figure 32: Inter Heater 1 Firing Rate (from Fuel Flow Rate) 

Figure 33: Inter Heater 1 Firing Rate Comparison 





Figure 34: Charge Rate × ∆T Vs Firing Rate of Inter Heater 1 

Figure 35: Inter Heater 1 Bridge Wall Temperature Vs Firing Rate (Provided 

by Client 





Observations on No.1 Inter heater Graphs 

The heater is operating at a lower process feed inlet temperature than the 

design. The average operating process feed inlet temperature is 727°F 

and the design process feed inlet temperature is 801°F. 




Average Operating process feed temperature rise is higher than the 

design value by 20°F. 



the design value of 12 psig. 

In current operation, average excess O2 at arch is 4.38% which is higher 








4.1.4 No. 2 Inter Heater Analysis 









Figure 42 Bridge wall O2 AI11B 












Table 17: Analysis of Operating Data of No. 2 Inter Heater 

Description Units Max Avg Design 




Charge Rate X ∆T Mlb ºF/hr 41,584 36,460 33,453 

Tube Metal Temp. ºF 1,060 1,006 1,125 

Bridge Wall Temp. ºF 1,431 1,374 1,500 

Bridge wall O2 % 9.53 4.47 3.00 








MMBtu/hr 80.15 56.18 50.0 

MMBtu/hr 74.50 62.61 50.0 












































by Client) 





Observations on No.2 Inter heater Graphs: 

The heater is operating at a lower process feed inlet temperature than the 






Average operating process feed temperature rise is higher than the design 

value by 20°F. 




In current operation, average excess O2 at arch is 4.47%, which is higher 








4.1.5 No. 3 Inter Heater 


Figure 

No. 

Parameters 

Tag No. 







Figure 56 Bridge wall O2 AI11A 












Table 19: Analysis of Operating Data of No.3 Inter Heater 




Temperature Rise ºF 81.0 74.7 76.0 

Charge Rate X ∆T Mlb ºF/hr 22,841 19,710 16,092 

Tube Metal 

Temperature 

Bridge Wall 

Temperature 

ºF 1,053 1,004 1,100 

ºF 1,500 1,434 1,500 

Bridge wall O2 % 7.66 4.43 3.00 




Firing Rate Based 

on Fuel Flow Rate 



MMBtu/hr 38.67 26.92 21.5 

MMBtu/hr 37.80 31.75 21.5 












































by Client) 





Observations on No.3 Interheater Graphs: 

The heater is operating at 87°F lower process feed inlet temperature than 









In current operation, average excess O2 at arch is 4.43%, which is higher 








4.1.6 Convection Section: 

Table 20: List of Graphs of Convection Section 

Figure 

No. 

Parameters 

Tag No. 

Figure 64 Saturated Water Flow Rate (MGPM) FI69 

Figure 65 Saturated Water Flow Rate (Mlb/hr) Calculated 

Figure 66 Total Steam Flow Rate FI68 

Figure 67 Boiler Feed Water Flow Rate FC65 

Figure 68 BFW Coil Inlet Temperature TI200B 

Figure 69 BFW Coil Outlet Temperature TI206 

Figure 70 BFW Coil Temperature Rise Calculated 

Figure 71 Average Bridge Wall Temperature Calculated 

Figure 72 Flue Gas Leaving Convection Section TI207 

Figure 73 Flue Gas Temperature Approach Calculated 

Figure 74 Flue Gas ΔT Across Convection Calculated 

Figure 75 Total Firing Rate Calculated 

Figure 76 Total Firing Rate Based on Fuel Flow Rate Calculated 

Figure 77 Total Firing Rate Comparison - 

Figure 78 

Flue Gas Temperature at Convection Exit 

Vs Total Firing Rate 

- 

Figure 79 Draft Profile at Entry of Convection PI245 

Figure 80 Excess O2 at Arch Calculated 

Figure 81 Stack Damper Position HC210.OP 





Table 21: Analysis of Operating Data of Convection Section 


Saturated Water 

Flow Rate 

Saturated Water 

Flow Rate 

Total Steam Flow 

Rate 

MGPM 1.91 1.55 1.15 

Mlb/hr 781.3 632.8 574.2 

Mlb/hr 69.30 57.48 55.97 

BFW Flow Rate GPM 173.84 140.36 141.63 

BFW Coil Inlet 

Temperature 

BFW Coil Outlet 

Temperature 

BFW Coil 

Temperature Rise 

Average Bridge Wall 

Temperature 

Flue Gas Leaving 


Flue Gas Temp. 

Approach 

Flue Gas ΔT Across 

Convection 

ºF 277 265 300 

ºF 370 345.7 385 

ºF 93 81 85 

ºF 1,435 1,389 1,500 

ºF 602 571 448 

ºF 337 306 148 

ºF 851.8 817.7 1,052 

Total Firing Rate MMbtu/hr 270.5 235.2 177.5 

Total Firing Rate 

Based on Fuel Flow 

Rate 


Based on Fuel Gas 

Pressure 

Draft at Entry of 

Convection 

MMbtu/hr 302 213.2 177.5 

MMBtu/hr 274.7 234.2 177.5 

In WC -0.17 -0.43 -0.10 

Excess O2 at Arch % 8.17 4.44 3.00 

Stack Damper 

Position 

% 33.35 25.8 - 





Figure 64: Steam Generation Coil Circulation (MGPM) 

Figure 65: Steam generation Coil Circulation (Mlb/hr) 





Figure 66: Flow Rate of Steam Generated 

Figure 67: Boiler Feed Water Flow Rate (GPM) 





Figure 68: BFW Coil Inlet Temperature 

Figure 69: BFW Coil Outlet Temperature 





Figure 70: BFW Coil Temperature Rise 

Figure 71: Average Flue Gas Temperature Leaving Radiant Section 





Figure 72: Flue Gas Temperature Leaving Convection Section 

Figure 73: Flue Gas Temperature Approach 





Figure 74: Flue Gas ΔT Across Convection 

Observations on Convection Section Graphs 

Total steam generated is closer to the design. The average steam 

generated is 57.48 Mlb/hr and the design steam generated is 55.97 

Mlb/hr. 

The BFW inlet temperature is lower than the design. The average 

operating BFW inlet temperature is 265°F and the design BFW inlet 

temperature is 300°F. 

The BFW outlet temperature is lower than the design. The average 

operating BFW outlet temperature is 346°F and the design BFW outlet 

temperature is 385°F. 

Platformer heater is operating at a lower efficiency than the design. 

The average flue gas exit temperature is 571°F and the design flue 

gas exit temperature is 448°F. 

Average flue gas temperature approach is higher than the design. The 

average approach is 306°F and the design approach is 148°F. 





Figure 75: Total Firing Rate (Provided by Client) 

Figure 76: Total Firing Rate (from Fuel Flow Rate) 





Figure 77: Total Firing Rate Comparison 

Figure 78: Flue Gas Temperature at Convection Exit Vs Total Firing Rate 





Figure 79: Draft at Convection Entry 

Figure 80: Average Excess O2 at Radiant Exit 





Figure 81: Stack Damper Position 

Observations 

The average total firing rate is 235.22 MMBtu/hr and the design total 

firing rate is 177.51 MMBtu/hr. 

Overall Average excess O2 at arch is 4.44%. 





4.1.7 Fuel Data Analysis 

Table 22 : List of Graphs of Fuel 

Figure 

No. 

Parameters 

Tag No. 

Figure 82 Fuel Molecular Weight AL: 570500.E 

Figure 83 Fuel Net Heating Value 

Calculated 

Figure 84 

Fuel Molecular Weight Vs Fuel Heating 

Value 

Calculated 

Table 23: Analysis of Operating Data of Fuel 


Total Fuel Flow Rate MMSCFD 5.59 5.08 3.83 

Fuel Molecular 

Weight 

Lb / lbmol 26.48 18.73 19.61 

Fuel Heating Value Btu / Scf 1,363 1,007 1,120 





Figure 82: Fuel Gas Molecular Weight 

Figure 83: Fuel Gas Net Heating Value 





Figure 84: Fuel Gas Molecular Weight Vs Fuel Heating Value 





4.2 Current Operation Modeling 

Simulation of operating cases is done to determine how much the operating 

parameters deviate from the design data and to determine the effectiveness of 

the existing heat transfer surfaces. 

Basis for the Simulation 

To analyze the current operating conditions in detail, FIS has selected & 

simulated four operating cases as follows: 

1. DCS Case (06/25/18) 

2. Maximum Firing Case (06/11/18) 

3. Maximum Charge Case (08/30/18) 

4. Average Charge Case (04/13/18) 

The following operating data provided was assumed to be correct: 

a. Process parameters 

b. Stack temperature 

c. Excess O 2 % at exit of each radiant cell 

d. Fuel heating value 

e. Steam Generation 

f. BFW flow rates, inlet and outlet temperatures 

The operating simulations are also performed considering an emissivity of 1.0 for 

the radiant tubes. 





Table 24: Simulation of DCS Case (06/25/18) 

Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Total Heat Duty MMBtu/hr 158.9 - 201.5 


(Hydrocarbon) 

MMBtu/hr 105.6 - 131.6 

Naphtha Flowrate MBPD 18.2 23.5 23.5 

Recycle Gas 

Flowrate 

Total Feed Flowrate Lb/hr 211,731 

Waste Heat Duty 

(Steam) 


MMSCFD 26.4 36.0 36.0 

275,587 

(Calculated) 

275,587 

MMBtu/hr 53.36 - 69.91 

Radiant Heat Duty MMBtu/hr 105.6 - 131.6 


Heat Duty MMBtu/hr 37.49 - 44.54 

Heat Duty % 23.59 - 22.10 

Charge Flow Rate Lb/hr 211,731 275,587 275,587 

Inlet Temperature °F 807.5 720.0 721.2 

Inlet Pressure psig 71.9 86.3 87.0 

Outlet Temperature °F 1,010 913.0 913.0 

Outlet Pressure psig 69.8 84.3 84.3 

Coil Pressure Drop psi 2.1 2.0 2.7 

Radiant Heat 

Transfer Area 

ft 2 3,723 3,723 3,723 





Parameter 

Average Radiant 

Section Heat Flux 

Max Rad. Section 

Heat Flux 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 2 10,070 - 11,963 

Btu/hr/ft 2 18,778 - 21,792 

Fluid Mass Velocity lb/sec/ft 2 23.8 - 30.9 

Bridge Wall 

Temperature 

Maximum Inside 

Film Temperature 

Maximum Tube 

Metal Temperature 

Volumetric Heat 

Release 


°F 1,452 1,375 1,511 

°F 1,113 - 1,018 

°F 1,134 981.5 1,044 

Btu/hr/ft 3 2,287 - 2,848 


Heat Duty % 16.66 - 18.11 







Radiant Heat 

Transfer Area 




Heat Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,075 - 12,675 

Btu/hr/ft 2 12,700 - 27,684 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Fluid Mass Velocity lb/sec/ft 2 - - 30.9 

Bridge Wall 

Temperature 



Maximum Tube 



Release 


°F 1,500 1,406 1,656 

°F - - 1,052 

°F 1,125 975.5 1,085 

Btu/hr/ft 3 - - 4,030 


Heat Duty % 18.10 - 15.65 







Radiant Heat 

Transfer Area 

Average Rad. 



Heat Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,990 - 10,952 

Btu/hr/ft 2 22,215 - 23,902 


Bridge Wall 

Temperature 

°F 1,552 1,378 1,579 





Parameter 



Maximum Tube 



Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 1,122 - 1,021 

°F 1,148 982.5 1,050 

Btu/hr/ft 3 2,807 - 3,273 



Heat Duty % 8.32 - 9.45 







Radiant Heat 

Transfer Area 




Heat Flux 

ft 2 1,838 1,838 1,838 

Btu/hr/ft 2 7,193 - 10,365 

Btu/hr/ft 2 13,502 - 19,449 


Bridge Wall 

Temperature 



Maximum Tube 


°F 1,418 1,459 1,545 

°F 1,076 - 997.1 

°F 1,092 1,009 1,020 





Parameter 


Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 3 2,413 - 3,760 


Total Convection 

Heat Duty 


Entering Convection 

Section 

MMBtu/hr 53.36 - 69.91 

°F 1,491 1,405 1,576 



Heat Duty % 29.30 - 28.66 

Circulation Flow 

Rate 

Lb/hr 574,227 

655,232 

(Calculated) 

655,232 

Inlet Temperature °F 456 - 449.1 

Inlet Pressure Psig 510.1 - 517.0 

Outlet Temperature °F 462.7 - 462.7 

Outlet Pressure Psig 465.0 - 465.0 

Coil Pressure Drop Psi 45.1 - 52.0 

Steam Generation 

Flow Rate 

Heat Transfer Area 

(Bare) 


(Finned) 

Average SG Coil 


(BOS) 

Lb/hr 57,049 62,700 71,985 

Ft 2 2,375 2,375 2,375 

Ft 2 37,702 37,702 37,702 

Btu/hr/Ft 2 7,351 - 9,118 

Fluid Mass Velocity Lb/s/Ft 2 249.7 - 379.9 

Flue Gas Mass 

Velocity 

Lb/s/Ft 2 0.300 - 0.432 





Parameter 

Flue Gas Pressure 

Drop 

Flue Gas 

Temperature 

Leaving SG Coil 

Section 

Outside Heat 

Transfer Fin 


Maximum Fin Tip 

Temperature 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

in WC 0.076 - 0.158 

°F 555 - 765.7 

- - - 0.48 

°F 481.5 - 499.8 



Heat Duty % 4.19 - 6.03 

Flow Rate Lb/hr 70,918 

71,352 

(Calculated) 

75,584 


Inlet Pressure Psig 470 - 470.0 

Outlet Temperature °F 385.0 345.0 418.3 




(Finned) 

Average BFW Coil 


(BOS) 

Ft 2 22,620 22,621 22,621 

Btu/hr/Ft 2 2,758 - 5,120 


Flue Gas Mass 

Velocity 

Outside Heat 

Transfer Fin 

Lb/s/Ft 2 0.258 - 0.432 

- - - 0.48 





Parameter 


Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 


Drop 

Flue Gas 

Temperature 

Leaving BFW Coil 

Section 


Temperature 

in WC - - 0.062 

°F 448 584 583.2 

°F 415 - 462.7 

Combustion 

Fuel Gas Heating 

Value (LHV) 

Total Fuel Gas Flow 

Rate 

Total Combustion Air 

Flow Rate 

Combustion Air 

Temperature 

Total Flue Gas Flow 

Rate 


(LHV) 

Btu/Scf 1,118 1,259 1,258 

Lb/hr 8,248 11,322 12,592 

Lb/hr 159,224 - 228,450 

°F 60 - 60 

Lb/hr 167,472 - 241,042 

MMBtu/hr 178.0 262.0 239.7 

Heat Loss % 2 - 2 

Thermal Efficiency % 89.3 - 84.1 


Fuel Gas Flow Rate Lb/hr 2,873 3,745 4,056 

Combustion Air Flow 

Rate 

Lb/hr 55,460 - 72,012 

Flue Gas Flow Rate Lb/hr 58,333 - 76,068 


Excess O2 % 3.00 4.40 4.37 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Excess Air % 15.0 24.3 24.3 




Rate 

Lb/hr 39,806 - 68,708 



Excess O2 % 3.00 5.1 5.08 

Excess Air % 15.0 29.5 29.5 




Rate 

Lb/hr 44,726 - 56,657 



Excess O2 % 3.00 4.40 5.08 

Excess Air % 15.0 29.5 29.5 


Fuel Gas Flow Rate Lb/hr 996 1,464 1,760 


Rate 

Lb/hr 19,232 - 31,073 






Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 


Excess O2 % 3.00 4.30 4.27 

Excess Air % 15.0 23.6 23.6 





Table 25: Simulation of Maximum Firing Case (06/11/18) 

Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 



(Hydrocarbon) 

MMBtu/hr 105.6 - 137.7 


Recycle Gas Flowrate MMSCFD 26.4 35.0 35.0 



(Steam) 


285,689 

(Calculated) 

285,689 

MMBtu/hr 53.36 - 74.18 




Heat Duty % 23.59 - 20.82 



Inlet Pressure psig 71.9 - 92.4 



Coil Pressure Drop psi 2.1 - 2.8 

Radiant Heat Transfer 

Area 

ft 2 3,723 3,723 3,723 





Parameter 



Max Rad. Section Heat 

Flux 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 2 10,070 - 11,851 

Btu/hr/ft 2 18,778 - 21,590 


Bridge Wall 

Temperature 


Temperature 


Temperature 


Release 


°F 1,452 1,380 1,502 

°F 1,113 - 1,013 

°F 1,134 1,010 1,039 

Btu/hr/ft 3 2,287 - 2,815 


Heat Duty % 16.44 - 18.17 








Area 




Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,073 - 13,376 

Btu/hr/ft 2 20,236 - 29,242 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 


Bridge Wall 

Temperature 


Temperature 


Temperature 


Release 


°F 1,512 1,425 1,684 

°F 1,131 - 1,063 

°F 1,154 1,028 1,099 

Btu/hr/ft 3 2,537 - 4,275 


Heat Duty % 18.10 - 16.52 








Area 

Average Rad. Section 

Heat Flux 


Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,990 - 12,160 

Btu/hr/ft 2 22,215 - 26,546 


Bridge Wall 

Temperature 

°F 1,552 1,394 1,631 





Parameter 


Temperature 


Temperature 


Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 1,122 - 1,044 

°F 1,148 1,013 1,077 

Btu/hr/ft 3 2,807 - 3,616 



Heat Duty % 8.32 - 9.46 








Area 




Flux 

ft 2 1,838 1,838 1,838 

Btu/hr/ft 2 7,193 - 10,903 

Btu/hr/ft 2 13,502 - 20,452 


Bridge Wall 

Temperature 


Temperature 


Temperature 

°F 1,418 1,473 1,572 

°F 1,076 - 1,009 

°F 1,092 995.3 1,034 





Parameter 


Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 3 2,413 - 4,074 


Total Convection Heat 

Duty 



Section 

MMBtu/hr 53.36 - 74.18 

°F 1,491 1,418 1,600 



Heat Duty % 29.30 - 29.16 

Circulation Flow Rate Lb/hr 574,227 

616,238 

(Calculated) 

616,238 


Inlet Pressure Psig 510.1 - 483.9 




Steam Generation Flow 

Rate 


(Bare) 


(Finned) 



(BOS) 

Lb/hr 57,049 64,193 76,326 

Ft 2 2,375 2,375 2,375 

Ft 2 37,702 37,702 37,702 

Btu/hr/Ft 2 7,351 - 9,755 


Flue Gas Mass Velocity Lb/s/Ft 2 0.300 - 0.447 





Parameter 


Drop 

Flue Gas Temperature 


Section 

Outside Heat Transfer 

Fin Efficiency Factor 


Temperature 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

in WC 0.076 - 0.168 

°F 555 - 767.5 

- - - 0.469 

°F 481.5 - 497.1 



Heat Duty % 4.28 - 5.85 


73,087 

(Calculated) 

80,142 







(Finned) 



(BOS) 

Ft 2 22,621 22,621 22,621 

Btu/hr/Ft 2 2,863 - 5,221 






Drop 

- - - 0.469 

in WC 0.027 - 0.066 





Parameter 



Section 


Temperature 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 407 586 588.6 

°F 415 - 461.7 

Combustion 

Fuel Gas Heating Value 

(LHV) 


Rate 


Flow Rate 


Temperature 


Rate 

Btu/Scf 1,118 1,362 1,365 

Lb/hr 8,248 11,328 12,605 

Lb/hr 159,224 - 236,668 

°F 60 - 60 

Lb/hr 167,472 - 249,273 

Total Firing Rate MMBtu/hr 178.0 270.5 252.0 






Rate 

Lb/hr 55,460 - 71,257 



Excess O2 % 3.00 3.95 3.91 

Excess Air % 15.0 21.0 21.0 






Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 



Rate 

Lb/hr 39,806 - 71,664 



Excess O2 % 3.00 4.34 4.32 

Excess Air % 15.0 23.8 23.8 




Rate 

Lb/hr 44,726 - 59,398 



Excess O2 % 3.00 3.70 3.68 

Excess Air % 15.0 19.5 19.5 




Rate 

Lb/hr 19,232 - 34,349 



Excess O2 % 3.00 4.18 4.15 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Excess Air % 15.0 22.6 22.6 





Table 26: Simulation of Maximum Charge Case (08/30/18) 

Design Operating Simulation 

Parameter Unit 

Simulation Data Output 



(Hydrocarbon) 

MMBtu/hr 105.6 - 134.7 


Recycle Gas 

Flowrate 



(Steam) 


MMSCFD 26.4 32 32 

283,420 

(Calculated) 

283,420 

MMBtu/hr 53.36 - 73.21 




Heat Duty % 23.59 - 20.67 





Outlet Pressure psig 69.8 - 91.0 


Radiant Heat 

Transfer Area 



ft 2 3,723 3,723 3,723 

Btu/hr/ft 2 10,070 - 11,544 





Parameter 


Heat Flux 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 2 18,778 - 21,028 


Bridge Wall 

Temperature 



Maximum Tube 



Release 


°F 1,452 1,375 1,483 

°F 1,113 - 1,008 

°F 1,134 996.7 1,033 

Btu/hr/ft 3 2,287 - 2,763 


Heat Duty % 16.44 - 17.41 


283,420 

(Calculated) 






Radiant Heat 

Transfer Area 




Heat Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,073 - 12,570 

Btu/hr/ft 2 20,236 - 27,438 






Parameter 

Bridge Wall 

Temperature 



Maximum Tube 



Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 1,512 1,417 1,638 

°F 1,131 - 1,039 

°F 1,154 1,004 1,073 

Btu/hr/ft 3 2,537 - 3,967 



Heat Duty % 18.10 - 17.10 







Radiant Heat 

Transfer Area 

Average Rad. 



Heat Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,990 - 12,352 

Btu/hr/ft 2 22,215 - 26,978 


Bridge Wall 

Temperature 



°F 1,552 1,417 1,637 

°F 1,122 - 1,051 





Parameter 

Maximum Tube 



Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 1,148 1,018 1,084 

Btu/hr/ft 3 2,807 - 3,779 



Heat Duty % 8.32 - 9.61 







Radiant Heat 

Transfer Area 




Heat Flux 

ft 2 1,838 1,838 1,838 

Btu/hr/ft 2 7,193 - 10,865 

Btu/hr/ft 2 13,502 - 20,380 


Bridge Wall 

Temperature 



Maximum Tube 



Release 

°F 1,418 1,458 1,563 

°F 1,076 - 1,008 

°F 1,092 1,020 1,032 

Btu/hr/ft 3 2,413 - 4,085 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 



Heat Duty 



Section 

MMBtu/hr 53.36 - 73.21 

°F 1,491 1,417 1,580 



Heat Duty % 29.30 - 29.19 

Circulation Flow 

Rate 

Lb/hr 574,227 

752,301 

(Calculated) 

752,301 






Steam Generation 

Flow Rate 


(Bare) 


(Finned) 



(BOS) 

Lb/hr 57,049 66,870 75,414 

Ft 2 2,375 2,375 2,375 

Ft 2 37,702 37,702 37,702 

Btu/hr/Ft 2 7,351 - 9,582 


Flue Gas Mass 

Velocity 


Drop 

Lb/s/Ft 2 0.300 - 0.448 

in WC 0.076 - 0.171 





Parameter 

Flue Gas 

Temperature 


Section 

Outside Heat 

Transfer Fin 



Temperature 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 555 - 770.0 

- - - 0.488 

°F 481.5 - 501.3 



Heat Duty % 4.28 - 6.02 


65,203 

(Calculated) 

79,185 


Inlet Pressure Psig 470 - 470 





(Finned) 



(BOS) 

Ft 2 22,621 22,621 22,621 

Btu/hr/Ft 2 2,863 - 5,271 


Flue Gas Mass 

Velocity 

Outside Heat 

Transfer Fin 


Lb/s/Ft 2 0.300 - 0.448 

- - - 0.488 





Parameter 


Drop 

Flue Gas 

Temperature 


Section 


Temperature 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

in WC 0.027 - 0.067 

°F 407 589 591.3 

°F 415 - 482.9 

Combustion 

Fuel Gas Heating 

Value (LHV) 


Rate 

Total Combustion 

Air Flow Rate 


Temperature 


Rate 

Btu/Scf 1,118 1,186 1,189 

Lb/hr 8,248 11,691 12,247 

Lb/hr 159,224 - 237,631 

°F 60 - 60 

Lb/hr 167,472 - 249,878 

Total Firing Rate MMBtu/hr 178.0 270 248.5 






Flow Rate 

Lb/hr 55,460 - 71,392 



Excess O2 % 3.00 3.96 3.94 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Excess Air % 15.0 21.0 21.0 




Flow Rate 

Lb/hr 39,806 - 67,217 



Excess O2 % 3.00 4.20 4.18 

Excess Air % 15.0 22.6 22.6 




Flow Rate 

Lb/hr 55,460 - 64,327 



Excess O2 % 3.00 3.91 3.91 

Excess Air % 15.0 20.8 20.8 




Flow Rate 

Lb/hr 19,232 - 34,695 






Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 


Excess O2 % 3.00 3.94 3.94 

Excess Air % 15.0 21.0 21.0 





Table 27: Simulation of Average Charge Case (04/13/18) 

Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 



(Hydrocarbon) 

MMBtu/hr 105.6 - 128.5 


Recycle Gas Flowrate MMSCFD 26.4 36.0 36.0 



(Steam) 


263,176 

(Calculated) 

263,176 

MMBtu/hr 53.36 - 66.60 




Heat Duty % 23.59 - 20.76 








Area 

ft 2 3,723 3,723 3,723 





Parameter 




Flux 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 2 10,070 - 10,881 

Btu/hr/ft 2 18,778 - 19,903 


Bridge Wall 

Temperature 


Temperature 


Temperature 


Release 


°F 1,452 1,373 1,459 

°F 1,113 - 1,028 

°F 1,134 1,024 1,052 

Btu/hr/ft 3 2,287 - 2,534 


Heat Duty % 16.44 - 18.25 








Area 




Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,073 - 12,365 

Btu/hr/ft 2 20,236 - 27,176 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 


Bridge Wall 

Temperature 


Temperature 


Temperature 


Release 


°F 1,512 1,427 1,640 

°F 1,131 - 1,085 

°F 1,154 1,046 1,118 

Btu/hr/ft 3 2,537 - 3,802 


Heat Duty % 18.10 - 18.09 








Area 


Heat Flux 


Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,990 - 12,261 

Btu/hr/ft 2 22,215 - 26,934 


Bridge Wall 

Temperature 

°F 1,552 1,415 1,639 





Parameter 


Temperature 


Temperature 


Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 1,122 - 1,084 

°F 1,148 1,049 1,117 

Btu/hr/ft 3 2,807 - 3,650 



Heat Duty % 8.32 - 8.76 








Area 




Flux 

ft 2 1,838 1,838 1,838 

Btu/hr/ft 2 7,193 - 9,298 

Btu/hr/ft 2 13,502 - 17,450 


Bridge Wall 

Temperature 


Temperature 


Temperature 

°F 1,418 1,435 1,496 

°F 1,076 - 1,017 

°F 1,092 1,023 1,038 





Parameter 


Release 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Btu/hr/ft 3 2,413 - 3,367 



Duty 



Section 

MMBtu/hr 53.36 - 66.60 

°F 1,491 1,413 1,567 



Heat Duty % 29.30 - 28.29 

Circulation Flow Rate Lb/hr 574,227 

582,126 

(Calculated) 

582,126 







Rate 


(Bare) 


(Finned) 


Section Heat Flux (BOS) 

Lb/hr 57,049 54,977 68,526 

Ft 2 2,375 2,375 2,375 

Ft 2 37,702 37,702 37,702 

Btu/hr/Ft 2 7,351 - 8,714 







Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Flue Gas Pressure Drop in WC 0.076 - 0.140 


Leaving SG Coil Section 




Temperature 


°F 555 - 749 

- - - 0.486 

°F 481.5 - 497.4 


Heat Duty % 4.28 - 5.85 


70,503 

(Calculated) 

71,952 







(Finned) 



Ft 2 22,621 22,621 22,621 

Btu/hr/Ft 2 2,863 - 4,804 





- - - 0.486 

Flue Gas Pressure Drop in WC 0.027 - 0.055 





Parameter 



Section 


Temperature 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

°F 407 565 567.9 

°F 415 - 452.3 

Combustion 


(LHV) 


Rate 


Flow Rate 


Temperature 


Rate 

Btu/Scf 1,118 1,096 1,098 

Lb/hr 8,248 10,421 11,359 

Lb/hr 159,224 - 213,356 

°F 60 - 60 

Lb/hr 167,472 - 224,715 







Rate 

Lb/hr 55,460 - 63,741 



Excess O2 % 3.00 3.51 3.52 

Excess Air % 15.0 18.3 18.3 






Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 



Rate 

Lb/hr 39,806 - 62,042 



Excess O2 % 3.00 3.57 3.57 

Excess Air % 15.0 18.6 18.6 




Rate 

Lb/hr 44,726 - 59,033 



Excess O2 % 3.00 3.12 3.11 

Excess Air % 15.0 15.8 15.8 




Rate 

Lb/hr 19,232 - 28,540 



Excess O2 % 3.00 4.00 3.99 





Parameter 

Unit 

Design 

Simulation 

Operating 

Data 

Simulation 

Output 

Excess Air % 15.0 21.3 21.3 





Operating Simulation Observations 

Convection tubes are fouled on flue gas side. Fins in the convection section 

are only 50% efficient. This is leading to higher flue gas temperature. 

Firing rates for design and the operating case are as follows. 

Description 

Actual (Datasheet/ 

Provided by Client) 

Firing rate, MMBtu/hr 

Calculated 

Design Case 177.5 178.0 

DCS Case (06/25/18) 262.0 239.7 

Maximum Firing Case 

(06/11/18) 

Average Charge Case 

(04/13/18) 

Maximum Charge Case 

(08/30/18) 

270.5 252.0 

233.0 230.4 

270.0 248.5 

 

We are not able to match the steam generation in the operating cases. 





Section 5 

Recommendations 

Marathon intends to operate the heater at 24.5 MBPD Naphtha Charge rate and 

36-38 MMSCFD of recycle gas flowrate during maximum octane rate. FIS 

considered 24.5 MBPD and 40 MMSCFD as total feed flow rate as the projected 

operating case. FIS proposes to increase the capacity of the heater based on FIS 

patented Split Flow Technology. The proposed total process heat duty with the 

new convection with Split Flow Technology is 191.7 MMBtu/hr. Existing heater 

process duty is 105.6 MMBtu/hr. The process duty at maximum charge rate is 

134.7 MMBtu/hr. 

5.1 Split Flow Technology 

In a reformer heater with a split flow, the process stream is divided in two streams 

and heated in parallel. The main stream continues to be heated as before in the 

radiant section. The split flow stream is heated in the convection section to the 

outlet temperature. The split flow convection section is designed by balancing the 

heat transfer and pressure drop with the radiant stream. 

The split flow piping runs from the inlet manifolds to the new convection coils and 

then return the convection section outlet split flow piping back to the outlet manifold 

from the radiant. 

The flow control can be achieved by introducing a variable resistance in the form 

of a butterfly control valve for heaters designed with low process side pressure 

drop. The split stream outlet temperature can be controlled by adjusting the flow 

through the convection section. These parallelly heated streams are mixed 

downstream and sent to the reformer reactors. 

5.2 Energy balance for process heat recovery in convection 

section 

FIS considered the permitted firing rate 280 MMBtu/hr (LHV) for the proposed 

design basis. The below table shows the amount of process heat recovered in 

the convection section. 





Table 28 : Proposed Convection Section Energy Balance 

Parameter Unit Value 

Total Firing Rate MMBtu/hr 280 

Total Radiant Process Duty MMBtu/hr 148.3 

Bridgewall Temperature °F 1,644 

Total Flue Gas Flow Rate lb/hr 277,645 

Process Coils 

Flue Gas Entry Temperature °F 1,644 

Flue Gas Exit Temperature °F 1,125 

Enthalpy of Flue Gas at Inlet Btu/lb 454.5 

Enthalpy of Flue Gas at 

Outlet 

Process Duty Absorbed in 


Btu/lb 295.7 

MMBtu/hr 44.08 

5.3 New Convection Section with Split Flow Technology 

FIS proposes to install a new convection section that accommodates process coils 

for the four radiant cells of Platformer Heater in the bottom portion of the convection 

section. Steam generation coils are accommodated on the top portion of 

convection Section. The heat transfer surface is optimized to achieve the total heat 

absorbed duty and to limit the firing rate. The summary of proposed case duty is 

as follows: 





Heater Section 

Proposed 

Heat Duty 

Proposed 

Radiant Duty 

Proposed 

Convection Duty 

MMBtu/hr 

No. 1 Interheater 66.13 49.22 16.91 

Charge Heater 50.08 39.31 10.77 



Total Process Duty 191.7 147.5 44.25 

Steam Generator 39.81 - 39.81 

BFW Preheat 9.82 - 9.82 

Debutanizer Duty 5.12 - 5.12 

5.4 Proposed Convection Section Design 

The new convection section is designed to cool the flue gases from 1,644°F to 

438°F. The proposed convection consists of 3 bare rows and 12 finned rows. Each 

row consists of 12 tubes. The following heat recovery sequence (in the order of 

decreasing flue gas temperature) will be adopted in the convection section (bottom 

to top): 

a. No.3 Interheater - Bottom 1 bare row 

b. Charge Heater – Next 2 bare rows 

c. No.2 Interheater - Next 1 finned row 

d. No.1 Interheater - Next 2 finned rows 

e. Steam Generator - Next 2 finned rows 

f. Debutanizer – Next 1 finned row 

g. Steam Generator - Next 3 finned rows 

h. Boiler Feed Water - Next 3 finned rows 

No.3 Interheater split flow coils 

The bottom row consists of 12 bare tubes of 4” NPS Sch.40 made of A335 Gr.P9 

material. The tubes are arranged in twelve passes. The No.3 Interheater split flow 





coils will be designed for a heat duty of 6.14 MMBtu/hr. The heat transfer area is 

792 ft 2 (bare). The flue gas temperature leaving the coil section is 1,573°F. 

Charge Heater split flow coils 

The next two rows consists of 24 bare tubes of 4” NPS Sch.40 made of A335 Gr.P9 

material. The tubes are arranged in twelve passes. The Charge heater split flow 

coils will be designed for a heat duty of 10.77 MMBtu/hr. The heat transfer area is 

1,583 ft 2 (bare). The flue gas temperature leaving the coil section is 1,449°F. 


The next row consists of 12 finned tubes of 4” NPS Sch.40 made of A335 Gr. P9 

material. The tubes are arranged in twelve passes. The No.2 Interheater split flow 

coils will be designed for a heat duty of 10.43 MMBtu/hr. The fins are of 0.5” ht. X 

0.06” thk. X 5 FPI configuration and made of 18Cr-8 Ni fin material. The heat 

transfer area is 5,243 ft 2 (finned). The flue gas temperature leaving the coil section 

is 1,326°F. The maximum fin tip temperature is 1,147°F. 


The next two rows consists of 24 finned tubes of 4” NPS Sch.40 made of A335 Gr. 

P9 material. The tubes are arranged in twelve passes. The No.1 Interheater split 

flow coils will be designed for a heat duty of 16.91 MMBtu/hr. The fins are of 0.75” 

ht. X 0.06” thk. X 5 FPI configuration and made of 18Cr-8 Ni fin material. The heat 


is 1,125°F. The maximum fin tip temperature is 1,140°F. 

The preliminary manifold sizes for the process convection split flow coil are as 

follows: 

a. Charge Heater: 14” NPS 

b. No.1 Interheater: 16” NPS 

c. No.2 Interheater: 14” NPS 

d. No.3 Interheater: 16” NPS 

Lower Steam Generator coils 

The next two finned rows consist of 24 finned tubes of 4” NPS Sch.80 made of 

A106 Gr.B tube material. The tubes are arranged in six passes. The lower steam 

generator coils will be designed for a heat duty of 25.5 MMBtu/hr. The fins are of 

0.75” ht. X 0.06” thk. X 5 FPI configuration and made of CS fin material. The heat 


is 813°F. The maximum fin tip temperature is 606°F. 

Debutanizer coils 





The next finned row consists of 12 finned tubes of 4” NPS Sch.40 made of 

A106 Gr.B tube material. The tubes are arranged in four passes. The Debutanizer 

finned row is sandwiched between lower and upper steam generation coils. The 

outlet from the adjacent Debutanizer heater is heated in series with the debutanizer 

coil in the Platformer convection. The Debutanizer coil in the Platformer convection 

is designed for a heat duty of 5.12 MMBtu/hr. It is designed to heat 75% of 

debutanizer process fluid (93,327 lb/hr) at 504°F. 

The fins are of 1” ht. X 0.06” X 5 FPI configuration and made of CS fin material. 

The heat transfer area is 10,573 ft 2 (finned). The flue gas temperature leaving the 

coil section is 749°F. The maximum fin tip temperature is 693°F. 

Upper Steam Generator coils 

The next three finned rows consist of 36 finned tubes of 4” NPS Sch.80 made of 

A106 Gr.B tube material. The tubes are arranged in six passes. The upper steam 

generator coils will be designed for a heat duty of 14.32 MMBtu/hr. The fins are of 

1” ht. X 0.06” thk. X 5 FPI configuration and made of CS fin material. The heat 

transfer area is 31,720 ft 2 (finned). The maximum fin tip temperature is 566°F. 

BFW Coils 

The last three finned rows consist of 36 finned tubes of 4” NPS Sch.80 made of 

A106 Gr.B tube material. The BFW coils will be designed for a heat duty of 9.82 

MMBtu/hr. The fins are of 1” ht. X 0.06” X 5 FPI configuration and made of CS fin 

material. The heat transfer area is 31,720 ft 2 (finned). The flue gas temperature 

leaving the coil section is 438°F. The maximum fin tip temperature is 476°F. 

The height of the proposed convection is increased by approximately 11-7/16”. 

The new top of stack elevation is 213.95 ft. 

The approximate weight of the existing and proposed convection section is 

366,976 lbs. and 395,226 lbs. respectively. The percentage increase in weight is 

8%. 

Refer to FIS-483-CIS-1002 (Sheets 1& 2 of 2) for Proposed Design Coil and 

Insulation Summary and FIS-483-CIS-1003 for existing and proposed 

convection comparison. 

Refer to FIS-483-PFD-1002 for Proposed Process Flow Diagram. 



EL+ 91'- 2 7/16" 

EL+ 88'- 1 7/16" 

EL+ 80'- 4 5/8" 

EL+ 72'- 8" 

Convection Section (Horizontal) (New) 

COIL SUMMARY 

Service: No. 3 Interheater Split Flow Coils (Bare) 

Intermediate Tube Support: 

Service: Charge Heater Split Flow Coils (Bare) 


Service: No. 2 Interheater Split Flow Coils (Finned) 

Fins: 


Service: No. 1 Interheater Split Flow Coils (Finned) 

Fins: 


Service: Steam Generation Coils (Finned) 

Fins: 


Service: Debutanizer Coils (Finned) 

Fins: 


Service: BFW Coils (Finned) 

Fins: 


INSULATION SUMMARY (New Module) 

Section Thk. 

Lining Description Plate Anchors 


PROPOSED CONVECTION SECTION


PROPOSED CONVECTION SECTION

EL+ 90'- 3" 

EL+ 87'- 2" 

EL+ 80'- 7 3/8" 

EL+ 72'- 8" 

EL+ 91'- 2 7/16" 

EL+ 88'- 1 7/16" 

EL+ 80'- 4 5/8" 

EL+ 72'- 8" 


EXISTING V/S PROPOSED CONVECTION SECTION

PROPOSED DESIGN 

LEGEND: 

BFW INLET 65,200 300 

9.82 

441.8 

BFW OUTLET 

SG INLET 

752,301 

463 14.31 

DEBUTANIZER INLET 93,327 504 

5.12 

574.1 DEBUTANIZER OUTLET 

SG OUTLET 463 25.50 

16 

76,250 

16.91 

14 

66,080 

10.43 

14 

64,580 

10.77 

16 71,180 

6.14 

HCV 

HIC 

HCV 

HIC 

HCV 

HIC 

49.22 

39.31 38.77 20.18 

HCV 

HIC 

FUEL GAS 

288,160 728.7 

211,910 

988.7 

288,160 

741 

223,580 

IMPROVEMENTS 

953 

288,160 795.9 

FURNACE 222,080 

990 

288,160 

847.1 

216,980 

954 

PROPOSED DESIGN PROCESS FLOW DIAGRAM



Table 29: Proposed Simulation Comparison 

Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Total Heat Duty MMBtu/hr 158.9 207.9 246.5 


(Hydrocarbon) 

MMBtu/hr 105.6 134.7 191.7 


Recycle Gas Flowrate MMSCFD 26.4 32 40 

Total Feed Flowrate Lb/hr 211,731 283,420 288,160 

Debutanizer Heat Duty MMBtu/hr - - 5.12 


(Steam) 

MMBtu/hr 53.36 73.21 49.63 

Total Radiant Heat Duty MMBtu/hr 105.6 134.7 147.5 



MMBtu/hr - - 44.25 




Heat Duty MMBtu/hr 37.49 42.98 49.22 

Heat Duty % 23.59 20.67 19.94 









Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 




Area 

Average Radiant Section 

Heat Flux 


Flux 

ft 2 3,723 3,723 3,723 

Btu/hr/ft 2 10,070 11,544 13,221 

Btu/hr/ft 2 18,778 21,028 24,562 

Fluid Mass Velocity lb/sec/ft 2 23.8 31.8 23.8 

Bridge Wall Temperature °F 1,452 1,483 1,575 


Temperature 


Temperature 

°F 1,113 1,008 1,126 

°F 1,134 1,033 1,154 

Volumetric Heat Release Btu/hr/ft 3 2,287 2,763 3,306 


Heat Duty MMBtu/hr - - 16.91 

Heat Duty % - - 6.85 

Charge Flow Rate Lb/hr - - 

76,250 

(26.4% split) 

Inlet Temperature °F - - 728.9 

Inlet Pressure Psig - - 71.8 

Outlet Temperature °F - - 987.4 

Outlet Pressure Psig - - 70.2 

Fluid Pressure Drop Psi - - 1.6 





Parameter 

Convection Heat Transfer 

Area (Finned) 

Average Conv. Sec. Heat 

Flux (BOS) 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Ft 2 - - 15,596 

Btu/hr/Ft 2 - - 10,680 

Fluid Mass Velocity Lb/s/Ft 2 - - 20.0 

Flue Gas Mass Velocity Lb/s/Ft 2 - - 0.452 

Flue Gas Pressure Drop In WC - - 0.071 

Flue Gas Temp. leaving 

the Coil Section 


Temperature 

°F - - 1,125 

°F - - 1,140 





Heat Duty % 16.44 17.41 15.93 

Charge Flow Rate Lb/hr 211,731 

283,420 

(Calculated) 

223,580 







Area 

ft 2 2,879 2,879 2,879 





Parameter 


Heat Flux 


Flux 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Btu/hr/ft 2 9,073 12,570 13,654 

Btu/hr/ft 2 20,236 27,438 30,287 


Bridge Wall Temperature °F 1,512 1,638 1,699 


Temperature 


Temperature 

°F 1,131 1,039 1,134 

°F 1,154 1,073 1,170 




Heat Duty % - - 4.36 


64,580 

(22.4% split) 







Area (Bare) 


Flux (BOS) 

Ft 2 - - 1,583 

Btu/hr/Ft 2 - - 6,804 






Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 






°F - - 1,449 




Heat Duty % 18.10 17.10 15.71 

Charge Flow Ra Lb/hr 211,731 283,420 222,080 







Area 


Heat Flux 


Flux 

ft 2 2,879 2,879 2,879 

Btu/hr/ft 2 9,990 12,352 13,466 

Btu/hr/ft 2 22,215 26,978 29,885 







Parameter 


Temperature 


Temperature 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

°F 1,122 1,051 1,138 

°F 1,148 1,084 1,173 




Heat Duty % - - 4.23 


66,080 

(22.9% split) 







Area (Finned) 


Flux (BOS) 

Ft 2 - - 5,243 

Btu/hr/Ft 2 - - 13,174 







Temperature 

°F - - 1,326 

°F - - 1,147 





Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 





Heat Duty % 8.32 9.61 8.18 








Area 


Heat Flux 


Flux 

ft 2 1,838 1,838 1,838 

Btu/hr/ft 2 7,193 10,865 10,979 

Btu/hr/ft 2 13,502 20,380 20,591 




Temperature 


Temperature 

°F 1,076 1,008 1,056 

°F 1,092 1,032 1,080 





Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 




Heat Duty % - - 2.49 


71,180 

(24.7% split) 







Area (Bare) 


Flux (BOS) 

Ft 2 - - 792 

Btu/hr/Ft 2 - - 7,753 






°F - - 1,573 

Heat Recovery Coils 


Duty (Process + Heat 

Recovery Coils) 

MMBtu/hr 53.36 73.21 99.0 





Parameter 

Flue Gas Temp. Entering 


Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

°F 1,491 1,580 1,644 

Debutanizer Coils 


Heat Duty % - - 2.08 

Charge Flow Rate Lb/hr - - 93,327 

Inlet Temperature °F - - 504 





Conv. Heat Transfer Area 

(Finned) 

Average Convection 


Ft 2 - - 10,573 

Btu/hr/Ft 2 - - 6,467 





the coil section 


Temperature 

°F - - 748.5 

°F - - 693 







Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Heat Duty % 29.30 29.19 16.15 

Circulation Flow Rate Lb/hr 574,227 752,301 752,301 

Inlet Temperature °F 456 450.8 472.5 

Inlet Pressure Psig 510.1 528.2 512.4 


Outlet Pressure Psig 465.0 465.0 465.0 

Coil Pressure Drop Psi 45.1 63.2 47.4 


Rate 


(Bare) 


(Finned) 

Average SG Coil Section 

Heat Flux (BOS) 

Lb/hr 57,049 75,414 53,061 

Ft 2 2,375 2,375 - 

Ft 2 37,702 37,702 47,316 

Btu/hr/Ft 2 7,351 9,582 10,057 

Fluid Mass Velocity Lb/s/Ft 2 249.7 436.2 436.2 

Flue Gas Mass Velocity Lb/s/Ft 2 0.300 0.448 0.475 

Flue Gas Pressure Drop in WC 0.076 0.171 0.103 


Leaving SG Coil Section 




Temperature 

°F 555 770.0 566.2 

- - 0.488 - 

°F 481.5 501.3 605.5 







Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Heat Duty % 4.28 6.02 3.98 

Flow Rate Lb/hr 70,918 79,185 65,200 


Inlet Pressure Psig 470 470 470.0 


Outlet Pressure Psig 467.9 468.2 469 

Coil Pressure Drop Psi 2.1 1.8 1.0 


(Finned) 



Ft 2 22,621 22,621 31,720 

Btu/hr/Ft 2 2,863 5,271 4,135 

Fluid Mass Velocity Lb/s/Ft 2 123.4 113.4 113.4 

Flue Gas Mass Velocity Lb/s/Ft 2 0.300 0.448 0.475 



- - 0.488 - 

Flue Gas Pressure Drop in WC 0.027 0.067 0.057 



Section 


Temperature 

°F 407 591.3 438.1 

°F 415 482.9 476.3 

Combustion 


(LHV) 

Btu/Scf 1,118 1,189 1,120 

Total Fuel Gas Flow Rate Lb/hr 8,248 12,247 12,972 





Parameter 


Flow Rate 


Temperature 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Lb/hr 159,224 237,631 264,673 

°F 60 60 60 

Total Flue Gas Flow Rate Lb/hr 167,472 249,878 277,645 


Heat Loss % 2 2 2 

Thermal Efficiency % 89.3 83.7 88.0 




Rate 

Lb/hr 55,460 71,392 84,423 

Flue Gas Flow Rate Lb/hr 58,333 75,083 88,574 


Excess O2 % 3.00 3.94 3.94 

Excess Air % 15.0 21.0 21.0 




Rate 

Lb/hr 39,806 67,217 74,274 



Excess O2 % 3.00 4.18 4.19 





Parameter 

Unit 

Design 

Simulation 

Maximum 

Charge 

Operating 

Case 

Proposed 

Simulation 

Excess Air % 15.0 22.6 22.6 




Rate 

Lb/hr 44,726 64,327 71,302 



Excess O2 % 3.00 3.91 3.91 

Excess Air % 15.0 20.8 20.8 




Rate 

Lb/hr 19,232 34,695 34,674 



Excess O2 % 3.00 3.94 3.96 

Excess Air % 15.0 21.0 21.0 





5.5 Effect of Charge Rate on the proposed design with split flow convection 

section 

When the heater operates at reduced loads (75% load and 50% load) for the same 

terminal conditions, the performance of the proposed design with split flow coils in 

convection is as follows: 

Parameter Units 100% Load 75% Load 50% Load 


Total Charge 

Rate 

lb/hr 288,160 216,120 144,080 


Total Process 

Heat Duty 

MMBtu/hr 191.7 147.4 98.8 

Bridgewall temp. °F 1,638 1,526 1,373 

Waste heat duty MMBtu/hr 49.63 35.45 21.71 

Steam Generated lb/hr 53,061 37,901 23,211 

Debutanizer duty MMBtu/hr 5.12 3.72 2.28 

Stack temp. °F 438.1 410.5 380.1 

Inter Heater 1 

Parameter Units Radiant Conv. Radiant Conv. Radiant Conv. 

Total Process 

Duty 

Process Heat 

Duty 

Charge Rate lb/hr 211,910 

Inlet / Outlet 

temp. 

Coil pressure 

drop 

MMBtu/hr 66.13 49.93 33.11 

MMBtu/hr 49.22 16.91 39.24 10.69 28.11 5.00 

76,250 

(26.46%) 

168,930 

47,190 

(21.84%) 

121,955 

22,125 

(15.36%) 

°F 717.2 / 988.7 717.2 / 988.7 719.4 / 988.7 

psi 2.0 1.6 1.3 0.6 0.7 0.1 





Charge Heater 


Total Process 

Duty 

Process Heat 

Duty 



temp. 

Coil pressure 

drop 


MMBtu/hr 50.08 39.23 26.04 

MMBtu/hr 39.31 10.77 31.63 7.60 21.54 4.50 

64,580 

(22.41 %) 

174,685 

41,435 

(19.17%) 

118,790 

25,290 

(17.55%) 

°F 739.8 / 953.0 733.1 / 953.0 732.8 / 953.0 

psi 1.3 0.8 0.8 0.3 0.4 0.1 


Total Process 

Duty 

Process Heat 

Duty 



temp. 

Coil pressure 

drop 


MMBtu/hr 49.20 37.73 25.59 

MMBtu/hr 38.77 10.43 31.12 6.61 22.50 3.09 

66,080 

(22.93 %) 

176,560 

39,560 

(18.30%) 

126,040 

18,040 

(12.52%) 

°F 796.0 / 990.0 794.1 / 990.0 791.5 / 990.0 

psi 2.2 0.8 1.4 0.3 0.7 0.1 


Total Process 

Duty 

Process Heat 

Duty 


MMBtu/hr 26.32 20.51 14.07 

MMBtu/hr 20.18 6.14 16.12 4.39 11.44 2.63 

71,180 

(24.70%) 

172,735 

43,385 

(20.07%) 

118,490 

25,590 

(17.76%) 






temp. 

Coil pressure 

drop 

°F 852.5 / 954.0 852.1 / 954.0 848.6 / 954.0 

psi 1.8 1.1 1.2 0.4 0.6 0.1 

6.2.1 Observations: 

Keeping the terminal conditions fixed, 

At 100% load, the percentage flow through the split flow coils in convection is 

in the range of 22.9 – 26.5%. 

At 75% load, the percentage flow through the split flow coils in convection is in 

the range of 18.3 – 21.8%. 

At 50% load, the percentage flow through the split flow coils in convection is in 

the range of 12.5-17.8%. 





5.6 Salient Features of Revamp Model 

Figure 85: Bridgewall Temperature Comparison 

If the existing heater is operated at projected conditions, the bridgewall 

temperatures in all cells will be very high. For the projected operating 

condition, the estimated bridge wall temperature in No.1 Interheater is 

1,729°F, Charge heater is 1,849°F, No.2 Interheater is 1,855°F and No.3 

Interheater is 1,761°F. In proposed heater, the bridgewall temperatures 

will be 154°F lower in No.1 Interheater, 150°F lower in Charge heater, 

157°F lower in No.2 Interheater and 183°F lower in No.3 Interheater. 

With the proposed design, the bridge wall temperatures will be reduced 

significantly in all cells. 





Figure 86: Firing Rate Comparison 

If existing heater is operated at projected conditions, the firing rate in each 

cell will be very high. With proposed option firing rate in No.1 Interheater 

is 31% lower, in Charge Heater is 30% lower, in No.2 Interheater is 31.7% 

lower and in No.3 Interheater is 36.6% lower. The total firing rate in the 

proposed design will be 32% lower. 





Figure 87: Flue Gas Convection Exit Temperature 

The average flue gas convection exit temperature for the operating cases is 590°F. 

The estimated flue gas convection exit temperature for the existing heater at 

proposed condition is 722°F. The flue gas convection exit temperature for the 

proposed design is 438°F. 





Section 6 

Cost Estimation 

This section provides cost estimate (± 30%) for the revamp of Platformer Heater 

(1-44-B-1/2/3/4). It also provides the details of design, engineering, materials, 

fabrication and erection activities considered for the revamp work. 

6.1 Basis of Cost Estimation 

The cost estimate provided here is based on the following assumptions: 

Construction prices are based on the USGC (US Gulf Coast) labor. 

Heater Steel and Coil Fabrication, refractory installation and dry-out of the 

refractory wherever applicable are included in the cost estimate. 

Crane, scaffolding, piping, and instrumentation cost is included wherever 

applicable. 

Transportation cost up to the refinery is included 

The removal of dumpsters, final disposal of removed tubes, casing, etc. are 

not included. 

The heater would be blinded, isolated, opened and closed by others 

No new foundation or civil work is anticipated in this revamp 

6.3 Proposed Design: New Convection Section 

Proposed Design consists of replacement of existing convection section with a new 

convection section. It consists of split flow coils, waste heat recovery coils and 

debutanizer coils. The convection section height is ~1 ft more than the existing 

convection section. New convection section will be supplied in two modules. New 

debutanizer flue gas duct module will be supplied. The existing convection 

platforms will be reused. As the convection height is increased, new debutanizer 

reboiler flue gas duct module and a ladder will be supplied. 





6.3.1 Scope of Supply 

The following items are considered as prefabricated and supplied to the site for 

installation: 

New convection modules complete with coils, supports, refractory and 

manifolds 

New refractory lined debutanizer flue gas duct module 

New piping, valves and other hardware for split flow inlet and outlet lines 

tying between the new convection and existing radiant process inlet and 

outlet lines. 

6.3.2 Scope of Site Activity 

The following major site activities are envisaged: 

Demolish existing debutanizer reboiler flue gas duct to platformer stack 

(Partially) 

Dismantle existing platformer off take ducts and platforms 

Dismantle existing platformer stack with platforms 

Demolish existing convection modules, platforms (Reusable) and structures 

Install new convection modules and structures 

Re-install existing convection platforms with new ladder 

Re-install existing platformer stack with platforms and ladders 

Re-install existing off take ducts and platforms 

Install new debutanizer reboiler flue gas duct module to platformer stack 

Install split flow piping and valves 

6.3.3 Revamp Cost Estimate 

The cost estimates for increasing the capacity and improving efficiency in 

platformer heater is summarized below: 

S. No. Description 

Cost 

(Million USD) 

1 Convection Pressure Parts, Finning and Coil Fabrication 1.01 

2 Convection Intermediate Tube Sheets 0.40 

3 Steel fabrication, Refractory & Anchors 1.31 

4 

Split Flow Piping, Flow Control Valves and 

Instrumentation 

1.00 

Total Supply Cost (Hardware Cost) 3.72 



5 



Dismantling and erection, of convection modules and 

split flow piping (50% of Supply Cost) 

1.86 

6 Crane & rigger (45% of Supply Cost) 1.67 

7 Scaffolding (15% of Supply Cost) 0.56 

Total Direct Cost (Supply + Erection) 7.81 

8 Contingency (10% of Direct Cost) 0.78 

9 Design, Engineering and Licensing Fee 1.40 

Total Cost 9.99 

6.3.4 Project Schedule 

Convection Design, Engineering, Procurement and Shop Fabrication will 

require 10 to 12 months 

Site Installation will require approx. 35 working days with 2 nos of 12-hour 

work shifts 





7.1 List of P & ID’s 

Section 7 

Appendix 

S. No Description Drawing No. 

1 P&ID LPCCR Platformer 14968 Sheet 02 

2 

P&ID LPCCR Platformer - Steam Generator 


3 P&ID LPCCR Platformer – Firing Controls 

14968 Sheet 22 

14968 Sheet 

17/18/19/20 

7.2 List of Documents & Drawings 

S. No Description Document No. 

1 Heater Datasheet - 

2 Burner Datasheet 

CA-BU-S87636-801 

to 819-0 

3 Capacity-Pressure Curve for Burners - 

4 44B5 Debut Reboiler Burner Data Sheet - 

5 44B5 Debut Reboiler Specification Sheet - 

6 44B5 Debut Reboiler Burner Curve II - 

7 44B5 Debut Reboiler Burner Curve I - 

8 DCS Print Outs & PI Screenshots - 

9 

10 

11 

12 

Convection Section Photos, Burner Photos, 

Refinery Pictures 

Heater General Arrangement Drawing- 

Longitudinal Section 

Heater General Arrangement Drawing-Cross 

Section 

Heater General Arrangement Drawing-Plan & 

Details 

- 

1131-1-6-2 E 

1131-1-6-3 B 

1131-1-6-4 C 






13 Bill of Material 1131-1-6-5E/4C 

14 Burner Arrangement-Longitudinal Sections 113137 

15 

16 

17 

18 

19 

Burner General Arrangement (Charge Heater 

Burners) 

Burner General Arrangement (Interheater-1 

Burner) 


Burner) 


Burner) 

ST-1-SE-FR SPL Pilot Assembly for Burners 

S87636-614/610-617619 

B-BU-S87636- 

607/608/611/612/61 

3/614 

B-BU-S87636- 

601/602/603/604/60 

5/606/610 

B-BU-S87636- 

609/615/616/617 

B-BU-S87636- 

618/619 

SB7636-620 

20 Steel Arrangement Radiant Section 1133-1-6-7B 

21 

(1-44-B-1, B-3) Radiant Coils & Headers (1992) 

Radiant Coil Arrangement 

1131-1-6-10-B 

22 (1-44-B-2, B-4) Radiant Coil Arrangement 1131-1-6-9-A 

23 Radiant Coil Arrangement for 1-44-B-1/2/3/4 46314 

24 General Notes & Coil Fabrication Notes 113306 

25 

26 

27 

28 

29 

Radiant Coils & Headers Wicket Pipe Bending 

Details 

(1-44-B-, B-2, B-3, B-4) Anchor Details for 

Radiant Arch Roof/End Walls/Floor/Radiant Wall 

Panels/Convection Section (Insulation & Anchor 

Details) 

(1-44-B-1, B-2, B-3, B-4) Insulation & Anchor 

Details for Radiant to Convection Section Duct 

(1-44-B-1, B-2, B-3, B-4) Steel Arrangement - 

Radiant to Convection Ducts 

(1-44-B-1, B-2, B-3, B-4) Radiant Coils & 

Headers (1992) Typical Details - Radiant & 

Convection Header Boxes 

CN-12-339-03- 

01/02/03/04 

- 

- 

1131-1-6-21-D 

121S-1-95M 

30 Steel Arrangement – Convection Section 1133-1-6-8F 






31 

32 

33 

(1-44-B-, B-2, B-3, B-4) Steel Arrangement 


(1-44-B-1, B-2, B-3, B-4) Steel Arrangement - 

Typical Details End Tube Sheet for Convection 

Section 

(1-44-B-1, B-2, B-3, B-4) Convection Section - 

Intermediate Tube Support - Alloy Casting 

1131-1-6-20-D 

121S-2-266M 

1131-1-6-7-A 

34 Finned Tube Details 113305 

35 Finned Tube Details 1133-4-6-5B 

36 General Arrangement Elevation and Section 113302 

37 General Arrangement Plan 113303 

38 Steel Fabrication General & Erection Notes 113310 

39 Steel Arrangements Plans – Platforms 1133-1-6-9C 

40 Foundation Loading Diagram 113301 

41 Miscellaneous Duct Details 121S1459 

42 Debutanizer Reboiler Flue Gas Duct to Stack 113132

FIS-483 Consolidated Engineering Study Report

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