Case Studies Identify Induced Gas Flotation as BET - IPEC

Application of Flotation
In
Produced & Waste Water Treatment
IPEC
Houston 2007
Shaya Movafaghian

OUTLINE:
• Introduction
• Evolution of Flotation Separation
• Available Flotation Techniques
• WEMCO flotation: History and Adaptation to offshore
applications
• WEMCO flotation: Offshore Performance and
Operating Data

Evolution of Gas Flotation
DGF/IGF
WEMCO
•Oil, Petrochemical
•Multiple stage enclosed tanks, vessels
•Sparger, rotor, eductor, revival of
dissolved gas pumps
DAF/IAF/Flotation
Filters
WEMCO
•Paper, Mining, Food
•Single/Multiple stage Tanks
•Sparger, rotor, eductor
DAF
•Municipal, Potable, Sewage
•Large open basins, ponds
•Dissolved air pumps
1900s
1930s
1960s
1970s
Today

Available Flotation Techniques
Compressed
Air
Skim
Compressed Gas
Source
Influent
Sludge
Effluent
Saturation-
Retention Tank
From
Process or
other source
To Process Tank

Available Flotation Techniques
• Dissolved Air/Gas floatation
– Oldest technique
– Lowest bubble size distribution (microbubble)
– Developed for large residence time, zero-velocity process.
– Full flow saturation, Split flow saturation, Partial Recycle
– Typically single stage tank for Fisheries/Fruit/Food/Textile with slow
settling floc.
– Resurrected for oil field recently with 25-50% recycle @ 40-70 psig and

BACKGROUND:
WEMCO and Floatation
• WEMCO has been a leading supplier of gas floatation machines
for mineral recovery since 1930s.
• In mid 1960s WEMCO introduced the concept for self-induced
gas floatation with first WEMCO (1+1) Depurator.
• In 1969 first gas induced technique was adopted for secondary
treatment of produced and waste water in petroleum industry in
collaboration with Gulf Oil Co. (ChevronTexaco).
• Today WEMCO Depurator has become an integral part of any
oil-water/waste-water treatment benchmarking process.

BACKGROUND:
Conventional Depurator

BACKGROUND:
Conventional Depurator

THEORY:
Kinetic Approach (Macro Scale)
• Floatation Kinetic Analysis (FKA) for oil field applications:
The most widely accepted kinetic model for IGF implies:
1. Rate of removal is a pseudo-first-order equation.
2. Rate of removal is a direct function of residence time.
(Churchil et al; Degner et al; Chen et al.)
dC
ln
dt
⎡
⎢
⎣
=
C t
C
0
⎤
⎥
⎦
- KC
= − Kt
………..…...(1)
………..…...(2)
C: Contaminant Concentration
t: Hydraulic residence time
K: Kinetic rate constant (empirically derived)
Co: Initial Concentration @ t = 0
Ct: Concentration @ t

THEORY:
Kinetic Valuation
• Commutative Removal Efficiency:
– Kinetic Model for the “n th ”Cell
⎡ 1
( ) ⎥ ⎤
C.R.E = 100 × ⎢1
−
n
⎣
1 + Kt
⎦
• Determinants of C.R.E:
– Residence time
• Individual cell residence time (t)
• Number of cells (n)
– System Kinetic rate constant (K)
• System chemistry
• Gas transfer rate
• Bubble size, population, distribution
• Other (geometric and hydraulic)
Others : Arnold’s mass transfer model (1983)
Cumulative Removal Efficiency [%]
………..…...(3)
100
90
80
70
60
50
40
30
20
10
n= 4
n-CELL KINETIC ANALYSIS
(kinetic rate cte.= 1.2)
n= 3
n= 2
n= 1
0
0.00 0.50 1.00 1.50 2.00
Cell Residence Time [min.]

CONVENTIONAL DESIGN:
Kinetic rate verification

CYLINDRICAL DESIGN:
4-Cell (3D)

CYLINDRICAL DESIGN:
Dual-Cell (3D)

CYLINRICAL DESIGN:
Standard Design Subcategories
CYLINDRICAL DEPURATOR
MOTION
FIXED
DUAL CELL
TWO-CELL
FOUR-CELL
n_CELL
5-DC
5-2C
5-4C
Operation Envelope
6-DC
8-DC
6-2C
8-2C
6-4C
8-4C
200000
180000
160000
10-DC
12-DC
10-2C
12-2C
10-4C
12-4C
Rated Cap. [bwpd]
140000
120000
100000
80000
60000
40000
20000
0
12-4C
10-4CX
10-4C
12-2C/DC
8-4C
10-2C/DC
6-4C
8-2C/DC
5-4C
6-2C/DC
5-2C/DC

Performance and Operation Data
• Platform GS Mike Cabinda, Angola (2002-03)
Division of Cooper Cameron Corp.

Gathering Station Mike
Greater Tackula Area, Angola
Courtesy of ChevronTexaco 2002 Supplement to the Annual Report

GS Mike, Cabinda Angola
Pilot Cylindrical Depurator 13 MBWPD

GS Mike Test Results (July-August 2002)
Process Parameters

GS Mike Test Results (July-August 2002)
Four-Cell: Inlet Conditions
Four-Cell Cylindrical Depurator Prototype
Cabinda Angola Platform Gathering Station Mike
20,000
18,000
16,000
Flow
Inlet Contaminant
Outlet Contaminant
250
200
Flowrate [bwpd]
14,000
12,000
10,000
8,000
6,000
150
100
Contaminant [ppm]
4,000
50
2,000
0
0
0 20 40 60 80 100
Test No.

GS Mike Test Results (July-August 2002)
Four-Cell: Efficiency
Four-Cell Cylindrical Depurator Prototype
Cabinda Angola Platform Gathering Station Mike
Removal Efficiency [%]
100
90
80
70
60
50
40
30
20
10
0
Removal Efficiency
0.4
Predicted Removal Efficiency
Residence Time
0.2
0.0
0 20 40 60 80 100
Test No.
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
Residence Time [min.]

GS Mike Test Results (July-August 2002) Four-
Cell: Performance Evaluation
Four-Cell Cylindrical Depurator Prototype
Cabinda Angola Platform Gathering Station Mike
(K= 1.2)
105
100
Removal Efficiency [%]
95
90
85
80
75
70
Removal Efficiency
Four-Cell Cylindrical Depurator Prototype
Cabinda Angola Platform Gathering Station Mike
(K= 1.2)
65
60
Predicted Removal Efficiency
0 20 40 60 80 100
Test No.
Calculated Removal Efficiency [%]
100
98
96
94
92
90
88
86
84
82
5% Error
-5% Error
80
80 82 84 86 88 90 92 94 96 98 100
Actual Removal Efficiency [%]

GS Mike Test Results (July-August 2002)
Four-Cell: Performance Evaluation
Four-Cell Cylindrical Depurator Prototype
Cabinda Angola Platform Gathering Station Mike
(K= 1)
105
100
Removal Efficiency [%]
95
90
85
80
75
70
65
60
Removal Efficiency
Predicted Removal Efficiency
0 20 40 60 80 100
Test No.
Calculated Removal Efficiency [%]
Four-Cell Cylindrical Depurator Prototype
Cabinda Angola Platform Gathering Station Mike
(K= 1)
100
98
96
94
92
90
88
86
84
82
4% Error
-4% Error
80
80 82 84 86 88 90 92 94 96 98 100
Actual Removal Efficiency [% ]

Performance and Operation Data
• Typhoon Production Facility GoM (2004-05)
Division of Cooper Cameron Corp.

Typhoon mini TLP, Green Canyon block 237 A
•Courtesy of ChevronTexaco Annual Report, Dec 2002

Specifications - Typhoon, GoM USA
Name
Typhoon
Location Blocks 236 and 237
Green Canyon area of the Gulf of Mexico
Distance from land
Water depths
100 miles off the coast of Louisiana
2000ft
Equity Chevron (operator) 50%
BHP 50%
Peak production
Field life of
Production
Topsides Structural Deck
Major Process Systems (Oil System)
Gas System
Produced Water System
40,000 barrels/day of oil
60 million ft3/day of gas
Six to eight years
Mini TLP
Two levels consisting of a 110’x110’ Main
Deck and a 110’x110’ Production Deck
(nominal dimensions)
40 MBPD
2 stage separation (2 phase separation in HP
Separator
3 phase separation in LP Separator)
60 MMSCFD – 2 stage Main Gas Compression
system
5 MMSCFD – 2 stage Vapour recovery
compression system
Gas separation in both HP and LP separators
Gas dehydration system
15 MBPD Hydrocyclones with downstream
Column Flotation Unit
•Courtesy of ChevronTexaco Annual Report, Dec 2002

Model 8-DC Cylindrical Depurator
• Unit overall dimensions: 8’-0” dia. X 19’-0” s/s
• Unit required capacity: 20300 bwpd
• Unit required efficiency: 96.6% suspended O&G

Installation at Typhoon (Jan. 2004)

Installation at Typhoon (Jan. 2004)

Typhoon Process Parameters
Snapshot Dec. 2004

Typhoon Test Results (April-Dec. 2004)
Dual-Cell: Sampling stats
Wemco 8-DC
Typhoon Production Facility
Sample Distribution
0.60
0.50
0.40
Total
Insoluble
Soluble
Frequncy
0.30
0.20
0.10
0.00
0 25 50 75 100 125 150
OIW [ppm]

Typhoon Test Results (April-Dec. 2004)
Dual-Cell: Inlet/Outlet condition
Wemco 8-DC
Typhoon Production Facility
OIW concentration [ppm]
700
600
500
400
300
200
100
0
Samples (4/1/04 to 12/31/04)
Inlet ppm
Soluble Out
Total Out
Inslouble Out

Typhoon Test Results (April-Dec. 2004)
Dual-Cell: Performance vs. predicted eff.
100
Wemco 8-DC
Typhoon Production Facility
Removal Efficiency
Removal Efficiency [ppm]
95
90
85
80
75
Insoluble RE %
96% Efficiency line
70
Apr
Jun
Aug
Sep
Nov
Dec

Typhoon Test Results (March-May 2005)
Dual-Cell: Performance vs. predicted eff.
Wemco 8-DC
Typhoon Production Facility
OIW concentration [ppm]
450
400
350
300
250
200
150
100
50
0
Feb
Mar
Apr
May
Jun
Samples (3/17/05 to 5/30/05)
Inlet ppm
Soluble out

Division of Cooper Cameron Corp.