2000 Hook-up Book - Spirax Sarco

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SYSTEM DESIGN 36 Draining Temperature Controlled Steam Equipment Absorption chillers are important sources of cooling necessary for many refinery processes. A typical example is the need to cool products (using large heat exchangers) after the stripping process in an “alky” unit. Products going to storage are generally maintained below 100°F. Steam is used to drive the absorption process at low pressure, typically below 15 psig. Condensate drainage becomes a very real concern. In this case, steam is supplied at 12 psig to the chiller through an automatic control valve. Condensate system backpressure is a constant 6-7 psig, considering the 30 ft. uphill pipe-run to the vented condensate receiver. The Refinery Contact Engineer recognized the potential for system stall (having previously used the Pressure Powered Pump to overcome other similar problems). Multi-Coil Heaters In many cases, a fluid is heated by passing it through a series of heat exchangers which are all provided with steam through a common control valve (Fig. 48). Multiple section air heater coils or “batteries” typify such applications, as also the multi-roll dryers used in laundries. While the load on the first heater is usually appreciably greater than the load on later heater sections, the proportion of the total load which each section takes is often a matter of “rule of thumb” or even conjecture. The temperature difference between the steam and the entering cold fluid can be designated ∆t 1. Similarly, the temperature difference between the steam and the outlet heated fluid can be ∆t 0. The ratio between ∆t 1 and ∆t 0 can be calculated, and will always be less than one, see Fig. 49 (page 37) If the chart at Figure 50 is entered on the horizontal axis at this ratio, a vertical can be taken upwards until the curve corresponding with the number of heaters or coils in use is intersected. A horizontal from this Case in Action: Absorption Chiller, Condensate Drainage point given the proportion of the total heater load which is carried by the first section. Multiplying this proportion by the total load given the condensate rate in this section, and enables a trap with sufficient capacity to be selected. If it is required to accurately determine the load in the second Air Inlet Temp. t i Figure 48 Multiple Coil Air Heater Solution Two Pressure Powered Pumps were installed in parallel, along with necessary steam traps, air vents and strainers . The Refinery supplied the reservoir and interconnecting piping. Benefits • Regardless of varying steam supply pressure, considering the throttling that naturally occurs through the automatic control valve, thorough condensate drainage is assured and cooling efficiency is maintained. • Installation cost was much lower with the Pressure Powered Pumps over electric pumps that were also being considered. Costly water and explosion proof control panels were not required. • Pump maintenance cost is also much lower through elimination of the need for mechanical seals and pump motors. Steam Temp. t s section, estimate the temperature at the outlet from the first section, and regard this as the inlet temperature for an assembly with one less section than before. Recalculate the ratio t s - t o/t s - ti 2, and re-enter the chart at this value to find the proportion of the remaining load taken by the “first” of the remaining sections. Air Outlet Temp. t o
Temp. Inlet Temp. t i ∆t i Single Section t s t i2 ∆t o Figure 49 Temperature Distribution in Multi-Coil Heater Outlet Temp. Paper Mills require a huge volume of air exchange. This means that a great deal of air heating is necessary, particularly during winter months. Air Make-Up systems are split between two general applications: a. Machine or Process Air Make-Up is supplied to t h e immediate area around the machine and, more specifically, to certain areas within the machine for higher temperature heating (i.e. Pocket Ventilation or PV coils). b. Mill Air Make-Up, which is distributed across the mill for HVAC comfort. Either application may be accomplished with single banks of coils or double-preheat/reheat coils, depending on heating requirements. The mill experienced a chronic problem of frozen Air Make-Up coils, typically associated with condensate flooding and waterhammer. The 50/150 psig steam coils ballooned and ruptured routinely, creating costly maintenance headaches and safety hazards. Several coils were removed from service, requiring extensive repair. t o Proportion of Load on First Section 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Case in Action: Air Make-Up Coil Drainage Multi-Coil Heaters Single Section Two Section Three Section Four Section Five Section 0.2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Ratio ∆to/∆ti Figure 50 Load on First Section of Multi-Coil Heater Solution Mill Engineers, working with the local Spirax Sarco Representative, developed a long-range plan to redesign and retrofit the entire Air Make-Up System. Over the last two years, approximately 20 Pressure Powered Pump /float & thermostatic trap closed-loop packages have been installed. The project will continue until the entire system is retrofitted. They have similarly retrofitted several shell and tube heat exchangers, improving water heating efficiency. Benefits • Energy savings are achieved through installation of pressurized closed-loop packages. There is no loss to flash. • Chemical savings are achieved because of the pressurized packages. Chemicals are not lost out the vent. • Desired air heating efficiency has been achieved. All retrofitted coils have operated properly and continuously since installation. Flooding has been eliminated. • Maintenance costs dropped dramatically with elimination of condensate flooding, water-hammer and freezing. • Personnel safety has improved as steam/condensate leaks have been reduced. 37 SYSTEM DESIGN
Page 1 and 2: DESIGN OF FLUID SYSTEMS HOOK-UPS
Page 3 and 4: Spirax Sarco Spirax Sarco is the re
Page 5: Section 1: System Design Informatio
Page 8 and 9: SYSTEM DESIGN 2 The Working Pressur
Page 10 and 11: SYSTEM DESIGN 4 Sizing Steam Lines
Page 12 and 13: SYSTEM DESIGN 6 Sizing Superheated
Page 14 and 15: SYSTEM DESIGN 8 Draining Steam Main
Page 16 and 17: SYSTEM DESIGN 10 Draining Steam Mai
Page 18 and 19: SYSTEM DESIGN 12 Steam Tracing The
Page 20 and 21: SYSTEM DESIGN 14 Steam Tracing Sizi
Page 22 and 23: SYSTEM DESIGN 16 Steam Tracing Trac
Page 24 and 25: SYSTEM DESIGN 18 Steam Tracing A si
Page 26 and 27: SYSTEM DESIGN 20 Pressure Reducing
Page 28 and 29: SYSTEM DESIGN 22 Parallel and Serie
Page 30 and 31: SYSTEM DESIGN 24 How to Size Temper
Page 32 and 33: SYSTEM DESIGN 26 Temperature Contro
Page 38 and 39: SYSTEM DESIGN 32 Makeup Air Heating
Page 40 and 41: SYSTEM DESIGN 34 Draining Temperatu
Page 44 and 45: SYSTEM DESIGN 38 Steam Trap Selecti
Page 46 and 47: SYSTEM DESIGN 40 Steam Trap Selecti
Page 48 and 49: SYSTEM DESIGN 42 Flash Steam Flash
Page 50 and 51: SYSTEM DESIGN 44 Flash Steam Flash
Page 52 and 53: SYSTEM DESIGN 46 Condensate Recover
Page 54 and 55: SYSTEM DESIGN 48 Condensate Pumping
Page 56 and 57: SYSTEM DESIGN 50 Clean Steam Printi
Page 58 and 59: SYSTEM DESIGN 52 Clean Steam Overal
Page 60 and 61: SYSTEM DESIGN 54 Clean Steam Figure
Page 62 and 63: SYSTEM DESIGN 56 Testing Steam Trap
Page 64 and 65: SYSTEM DESIGN 58 Spira-tec Trap Lea
Page 66 and 67: SYSTEM DESIGN 60 Steam Meters Densi
Page 68 and 69: SYSTEM DESIGN 62 Compressed Air Sys
Page 70 and 71: SYSTEM DESIGN 64 Compressed Air Sys
Page 72 and 73: SYSTEM DESIGN 66 Compressed Air Lin
Page 74 and 75: SYSTEM DESIGN 68 Typical Steam Cons
Page 76 and 77: SYSTEM DESIGN 70 Specific Heats and
Page 78 and 79: SYSTEM DESIGN 72 Specific Heats and
Page 80 and 81: SYSTEM DESIGN 74 Conversions To Con
Page 82 and 83: SYSTEM DESIGN 76 Flow of Water thro
Page 84 and 85: SYSTEM DESIGN 78 Moisture Content o
Page 86 and 87: SYSTEM DESIGN 80 ANSI Flange Standa
Page 89 and 90: HOOK-UP APPLICATION DIAGRAMS Sectio
Page 91 and 92: Figure II-3 Draining and Air Ventin
Page 93 and 94:
Figure II-8 Draining Steam Main whe
Page 95 and 96:
Figure II-12 Typical Pressure Reduc
Page 97 and 98:
Figure II-16 Installation of Pressu
Page 99 and 100:
Figure II-20 Typical Pneumatic Sing
Page 101 and 102:
Condensate Return Steam Supply Stea
Page 103 and 104:
Steam Supply Steam Supply Figure II
Page 105 and 106:
Figure II-31 Temperature Control of
Page 107 and 108:
Elevated or Pressurized Return P 2
Page 109 and 110:
Figure II-39 Controlling Temperatur
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Figure II-50 Trapping Small Utensil
Page 117 and 118:
Figure II-55 Draining and Air Venti
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Figure II-59 Air Venting and Conden
Page 121 and 122:
Evaporator Pressure Figure II-64 Dr
Page 123 and 124:
Figure II-68 Installation of Pump/T
Page 125 and 126:
Figure II-73 Draining Small Condens
Page 127 and 128:
Figure II-78 Flash Steam Recovery a
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Figure II-80 Heating Water using Re
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Figure II-82 Recovery of Flash Stea
Page 133 and 134:
Figure II-84 Flash Steam Condensing
Page 135 and 136:
Figure II-87 Tank Sterilization Cle
Page 137 and 138:
Steam Supply Figure II-93 Typical S
Page 139 and 140:
Figure II-97 Hand Operated Rotary F
Page 141 and 142:
Figure II-102 Freeze Proof Safety S
Page 143 and 144:
Figure II-106 Continuous Boiler Blo
Page 145 and 146:
Figure II-111 Controlling Temperatu
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141
Page 149 and 150:
PRODUCT INFORMATION Section 3
Page 151 and 152:
Steam Traps • Balanced Pressure T
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147
Page 155 and 156:
Subject Index Safety...............
Page 157 and 158:
Subject Index Radiation—Baseboard
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Argentina Spirax Sarco S.A. Ruta Pa
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2000 Hook-up Book - Spirax Sarco

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