Acid Plant Strong Acid Section - Sulphuric Acid
Transcript of Acid Plant Strong Acid Section - Sulphuric Acid
Confidential
Acid Plant Strong Acid Section
Garrett Palmquist
MECS Inc.
3 October 2010
Confidential
Topics for Discussion
Main Equipment and Its Purpose,
Operating Conditions, and Limits
Flow Schemes
Notable Failures
Confidential
Main Equipment and Its Purpose
Final Tower
Interpass Tower
Drying Tower
Pump TanksAcid Coolers
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Main Equipment and Its Purpose
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
FINAL
ABSORBING
TOWER
Strong Acid Towers
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWS CWS CWRCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERIPAT
ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANKINTERPASS TOWER
PUMP TANK
CWSCWR
FAT
ACID COOLER
FINAL TOWER
PUMP TANK
WATER WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
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Strong Acid Drying Tower
Purpose
Water vapor removed with strong sulfuric acid
Typically -40 °F gas dewpoint
Required to prevent acid condensation in downstream equipment in dry gas plants
Operating Conditions
93% - 98% H2SO4
120 – 180 °F (50 – 80 °C), colder at lower acid strength
Constant, uniform acid flow
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Strong Acid Absorbing Tower
Purpose
SO3 vapor absorbed and reacted with strong sulfuric acid
SO3 + H2O -> H2SO4 + Heat
Operating Conditions
98% - 99% H2SO4
170 – 180 °F (75 – 80 °C)
Constant, uniform acid flow
Materials
CS Brick-Lined
Alloy
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Strong Acid Tower Details- Distributors
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Strong Acid Tower Details- Packing and Supports
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Strong Acid Tower Details- Mist Eliminators
Mesh Pad
Mist Eliminator Tubesheet
Brownian
Diffusion
Impaction
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PUMP TANK
Main Equipment and Its Purpose
Strong Acid Pump Tanks
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWS CWS CWRCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERIPAT
ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANKINTERPASS TOWER
PUMP TANK
CWSCWR
FAT
ACID COOLER
FINAL TOWER
PUMP TANK
WATER WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
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Strong Acid Pump Tanks
Purpose: Hold acid when plant is shutdown and provide enough acid during operation for circulating pumps
Operating Conditions: Same as the towersMaterials
CS Brick-lined
Alloy
Components
Pumps
Acid Returns
Dilution Water Addition
Analyzers and Sample Stations
Overflow and Vent
Baffles
Safety Showers
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Strong Acid Pump Tanks - Internals
Dilution water addition
near side acid return
Pair of acid pumps
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Main Equipment and Its Purpose
Strong Acid Coolers
CWS CWR
ACID COOLER
CWR
CWS
ACID COOLER
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWS CWS CWRCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERIPAT
ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANKINTERPASS TOWER
PUMP TANK
CWSCWR
FAT
ACID COOLER
FINAL TOWER
PUMP TANK
WATER WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
Confidential
Strong Acid Coolers
Purpose: Remove heat from circulating acid using cooling water
or BFW
Operating Conditions:
93% - +99% acid
100 – 250 °F (40 – 120 °C), material dependent
Maximum acid velocity (corrosion)
Minimum water velocity (fouling)
Shell & Tube
Plate & Frame
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Strong Acid Coolers
Materials – Shell and Tube
316 / 304 SS anodically protected
Alloy (ZeCor, 310 SS, etc.)
Materials – Plate and Frame
Hastelloy C-276 (low temperature)
Hastelloy D-205 (high temperature, low chlorides)
Confidential
Strong Acid Piping
Alloy systems
310 SS (velocity sensitive)
ZeCor
Iron systems
MONDI
Other ductile iron
Other systems
Anodically-protected
Lined
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Common IPAT/FAT pump tank with crossflow stripperCommon IPAT/FAT pump tankSeparate pump tanks, SO2 stack / product limits
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWS CWS CWRCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERIPAT
ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANKINTERPASS TOWER
PUMP TANK
CWSCWR
FAT
ACID COOLER
FINAL TOWER
PUMP TANK
WATER WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWSCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANK
CWSCWR
COMMON
ACID COOLER
INTERPASS / FINAL TOWER
PUMP TANK
WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWSCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANK
CWSCWR
COMMON
ACID COOLER
INTERPASS / FINAL TOWER
PUMP TANK
WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
CROSS-
FLOW
STRIPPER
AIR
Flow Schemes
PRODUCT
ACID
FINAL TOWER
MIST
ELIMINATORS
CWS CWS CWS CWRCWRCWR
DRYING TOWER
MESH PAD
DRYING
TOWER
INTERPASS
ABSORBING
TOWER
DT ACID COOLERIPAT
ACID COOLERPRODUCT
ACID COOLER
INTERPASS
TOWER MIST
ELIMINATORS
FINAL
ABSORBING
TOWER
DT PUMPTANKINTERPASS TOWER
PUMP TANK
CWSCWR
FAT
ACID COOLER
FINAL TOWER
PUMP TANK
WATER WATER
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
PROCESS
GAS
Separate pump tanks, lax SO2 stack / product limits
Confidential
STEAM
INJECTION
VESSEL
HEAT
RECOVERY
TOWER
LP
STEAM
IMPORT
HRS BOILER
HRS
HEATER
HRS
PREHEATER
HRS
DILUTER
HEAT
RECOVERY
TOWER MIST
ELIMINATORS
GAS OUT
GAS IN
STAGE 2
ACID IN
TO ACID
SYSTEM
TREATED
WATER
DEAERATOR
AND BFW PUMP
IP STEAM
BLOWDOWN
TO ACID
SYSTEM
HRS
DRAIN PUMPS
FROM ACID
SYSTEM
Heat Recovery System (HRS)
Replaces tower and
pump tank
Replaces acid cooler(s)
Replaces the interpass circuit
Operates at 400 – 440 F, >99%
H2SO4
Recovers excess heat as 150
psig steam
Special alloy materials
More expensive, but offset
by steam product (>0.4 t/t)
>1000 MTPD, >10% SO2
440 F
99.6% H2SO4
400 F
99% H2SO4
150 psig steam Teflon-lined
ZeCor-310M
ZeCor-310M
Confidential
Acid System Failures – Packing Collapse
Hot shutdown for a FAT cooler leak
Acid circulation was temporarily stopped
Thermal shock to Aludur beams collapsed packing
Packing blocked
tower acid outlet
Acid level covered
gas inlet
Blower surged and
wave of acid
knocked brick
arches over
Confidential
Acid System Failures – Cooler Leak
Leak in drying tower cooler goes undetected for several
hours
System cannot be drained for several days
H2 corrosion by-product collects in IPAT and explodes
Tower, tubesheet, and mist eliminators damaged
Confidential
Acid System Failures – Distribution and Mist
Elimination
Contributors:
Corroded distributors
Plugged seal cups
Acid on the tubesheet
Damaged mist eliminators
Confidential
Acid System Failures – Distribution and Mist
Elimination
Bad Stack
Plugged and
corroded heat
exchanger
Black catalyst
Confidential
Thank you.