SULPHUR RECOVERY UNIT

WHY DO WE REQUIRE SULPHUR RECOVERY UNIT ? ?

SULPHUR RECOVERYWHY ?1) Corrosion

2) Causes Pollution to Atmosphere HYDRODESULFURISATIONRSH + H2(Mercaptan)

RH + H2S 2RH + H2S

RSR + 2H2(Sulphide)

RSSR + 3H2 H2Scombustion

2RH + 2H2S CO2 + SO2(in

(sulfur compounds in finished products)

atmosphere)

ACID RAIN

3) Statutory requirement of the governmentBHARAT STAGE NORMS : FUEL SPECIFICATION

Parameter Sulphur ppm max. Benzene Vol % max. Aromatics Vol % max. Olefins Vol % max. RON

BS-20001000/500

BS-II 500 3

BS-III 150 1 42

BS-IV 50 1 35 21 91/95

3/5 88/93

-

21

88/93 91/95

SRU BLOCKA typical Sulpher Recovery Unit complex consists of process units like:

Amine regeneration Unit Sour Water Stripping Unit Sulpher Recovery Unit Tail Gas Treating Unit

(ARU) (SWS) (SRU) (TGTU)

Sulphur recovery schematicLean Amine Acid GasAmine Regeneration Unit(ARU)

Stack Gas SO2Modified (SRU) Claus plantTail gas (TGU) clean-up

Incineration

Rich Amine Sour Gas Sour Water Sour water stripping(SWS) Sweet Water Sulphur Storage

AMINE REGENERATION UNIT Simple to understand and operate. Difficult to operate well. Easiest to mess up. The principal aim of operating an Amine Unit well is to keep the circulating amine clean. Easier said than done.

Diagram of Amine Regeneration Unit1.05 KG/CM2 RICH AMINE FROM UNITS 92 OC REGENERATOR AIR CONDENSER ACID GAS 0.95 KG/CM2 CW TO FLARE TO SRU 55 OC REGENERATOR REFLUX DRUM LP STEAM REGENERATOR REBOILERS LEAN SOLVENT TO UNITS

104 OC RICH SOLVENT FLASH DRUM 40 OC CW 59 OC LEAN SOLVENT TRIM COOLER 50 OC AMINE REGENERATOR COLUMN

59

OC

RICH/LEAN SOLVENT EXCH 72 OC

REGENERATOR TRIM CONDENSER

LEAN SOLVENT AIR COOLER

REGENERATOR REFLUX PUMP 127 OC

RICH AMINE PUMP

AMINE FILTER

AMINE CIRCULATION TANK (785 M3)

REGENERATOR BOTTOMS PUMP

127 OC

126 OC

LP CONDENSATE 8.0 KG/CM2 40 OC

LEAN SOLVENT PUMP

Diagram of Amine Regeneration Unit1.05 KG/CM2 RICH AMINE FROM UNITS 92 OC REGENERATOR AIR CONDENSER ACID GAS 0.95 KG/CM2 CW TO FLARE TO SRU 55 OC REGENERATOR REFLUX DRUM LP STEAM REGENERATOR REBOILERS LEAN SOLVENT TO UNITS

104 OC RICH SOLVENT FLASH DRUM 40 OC CW 59 OC LEAN SOLVENT TRIM COOLER 50 OC AMINE REGENERATOR COLUMN

59

OC

RICH/LEAN SOLVENT EXCH 72 OC

REGENERATOR TRIM CONDENSER

LEAN SOLVENT AIR COOLER

REGENERATOR REFLUX PUMP 127 OC

RICH AMINE PUMP

AMINE FILTER

AMINE CIRCULATION TANK (785 M3)

REGENERATOR BOTTOMS PUMP

127 OC

126 OC

LP CONDENSATE 8.0 KG/CM2 40 OC

LEAN SOLVENT PUMP

Diagram of Amine Regeneration Unit1.05 KG/CM2 RICH AMINE FROM UNITS 92 OC REGENERATOR AIR CONDENSER ACID GAS 0.95 KG/CM2 CW TO FLARE TO SRU 55 OC REGENERATOR REFLUX DRUM LP STEAM REGENERATOR REBOILERS LEAN SOLVENT TO UNITS

104 OC RICH SOLVENT FLASH DRUM 40 OC CW 59 OC LEAN SOLVENT TRIM COOLER 50 OC AMINE REGENERATOR COLUMN

59

OC

RICH/LEAN SOLVENT EXCH 72 OC

REGENERATOR TRIM CONDENSER

LEAN SOLVENT AIR COOLER

REGENERATOR REFLUX PUMP 127 OC

RICH AMINE PUMP

AMINE FILTER

AMINE CIRCULATION TANK (785 M3)

REGENERATOR BOTTOMS PUMP

127 OC

126 OC

LP CONDENSATE 8.0 KG/CM2 40 OC

LEAN SOLVENT PUMP

Diagram of Amine Regeneration Unit1.05 KG/CM2 RICH AMINE FROM UNITS 92 OC REGENERATOR AIR CONDENSER ACID GAS 0.95 KG/CM2 CW TO FLARE TO SRU 55 OC REGENERATOR REFLUX DRUM LP STEAM REGENERATOR REBOILERS LEAN SOLVENT TO UNITS

104 OC RICH SOLVENT FLASH DRUM 40 OC CW 59 OC LEAN SOLVENT TRIM COOLER 50 OC AMINE REGENERATOR COLUMN

59

OC

RICH/LEAN SOLVENT EXCH 72 OC

REGENERATOR TRIM CONDENSER

LEAN SOLVENT AIR COOLER

REGENERATOR REFLUX PUMP 127 OC

RICH AMINE PUMP

AMINE FILTER

AMINE CIRCULATION TANK (785 M3)

REGENERATOR BOTTOMS PUMP

127 OC

126 OC

LP CONDENSATE 8.0 KG/CM2 40 OC

LEAN SOLVENT PUMP

Diagram of Amine Regeneration Unit1.05 KG/CM2 RICH AMINE FROM UNITS 92 OC REGENERATOR AIR CONDENSER ACID GAS 0.95 KG/CM2 CW TO FLARE TO SRU 55 OC REGENERATOR REFLUX DRUM LP STEAM REGENERATOR REBOILERS LEAN SOLVENT TO UNITS

104 OC RICH SOLVENT FLASH DRUM 40 OC CW 59 OC LEAN SOLVENT TRIM COOLER 50 OC AMINE REGENERATOR COLUMN

59

OC

RICH/LEAN SOLVENT EXCH 72 OC

REGENERATOR TRIM CONDENSER

LEAN SOLVENT AIR COOLER

REGENERATOR REFLUX PUMP 127 OC

RICH AMINE PUMP

AMINE FILTER

AMINE CIRCULATION TANK (785 M3)

REGENERATOR BOTTOMS PUMP

127 OC

126 OC

LP CONDENSATE 8.0 KG/CM2 40 OC

LEAN SOLVENT PUMP

SOUR WATER STRIPPER UNIT STRIPS OUT H2S AND NH3 FROM SOUR WATER GENERATED IN PROCESS UNITS(HCU and DHDT). SIMPLE UNITS TO UNDERSTAND AND OPERATE. USUALLY OPERATE WELL. NH3 + H2S NH4+ + HS-

Diagram of Refinery Sour Water Stripper Unit0.9 SOUR WATER FROM UNITS REFINERY SOUR WATER STRIPPER COLUMN KG/CM2

90 OC SOUR GAS

TO FLARE

65 OC REFINERY STRIPPER CR AIR COOLER

TO SRU

SOUR WATER SURGE DRUM FEED/BOTTOMS EXCHANGER 71.6OC

92.4 OC

90 OC REFINERY STRIPPER CR PUMP 123.6 OC 123.8 OC LP STEAMREFINERY STRIPPER REBOILER

40 OC SWS FEED PUMPS STRIPPED WATER TO ETP 40 OC

STRIPPED WATER AIR COOLER 123.8 OC REFINERY STRIPPER BOTTOM PUMP

STRIPPED WATER TRIM COOLER STRIPPED WATER TO CDU/DCU

LP CONDENSATE LP CONDENSATE

Diagram of Refinery Sour Water Stripper Unit0.9 SOUR WATER FROM UNITS REFINERY SOUR WATER STRIPPER COLUMN KG/CM2

90 OC SOUR GAS

TO FLARE

65 OC REFINERY STRIPPER CR AIR COOLER

TO SRU

SOUR WATER SURGE DRUM FEED/BOTTOMS EXCHANGER 71.6OC

92.4 OC

90 OC REFINERY STRIPPER CR PUMP 123.6 OC 123.8 OC LP STEAMREFINERY STRIPPER REBOILER

40 OC SWS FEED PUMPS STRIPPED WATER TO ETP 40 OC

STRIPPED WATER AIR COOLER 123.8 OC REFINERY STRIPPER BOTTOM PUMP

STRIPPED WATER TRIM COOLER STRIPPED WATER TO CDU/DCU

LP CONDENSATE LP CONDENSATE

Diagram of Refinery Sour Water Stripper Unit0.9 SOUR WATER FROM UNITS REFINERY SOUR WATER STRIPPER COLUMN KG/CM2

90 OC SOUR GAS

TO FLARE

65 OC REFINERY STRIPPER CR AIR COOLER

TO SRU

SOUR WATER SURGE DRUM FEED/BOTTOMS EXCHANGER 71.6OC

92.4 OC

90 OC REFINERY STRIPPER CR PUMP 123.6 OC 123.8 OC LP STEAMREFINERY STRIPPER REBOILER

40 OC SWS FEED PUMPS STRIPPED WATER TO ETP 40 OC

STRIPPED WATER AIR COOLER 123.8 OC REFINERY STRIPPER BOTTOM PUMP

STRIPPED WATER TRIM COOLER STRIPPED WATER TO CDU/DCU

LP CONDENSATE LP CONDENSATE

Typical Acid Gas Composition ARUComponent Mole %

HydrogenWater Hydrogen Sulphide

0.04-.067.5- 8.5 86-92

Hydrocarbons

0.01- .03

Typical Sour Gas Composition SWSComponent Mole %

WaterHydrogen Sulphide Ammonia

40-4315-17 38-42

Hydrocarbons

1-2

SULPHUR RECOVERY UNIT USING MODIFIED CLAUS PROCESS

Modified-Claus ProcessAcid Gas Sour Gas Free flame reactor HP steam O2925-12500C (1700-23000F)

Wasteheat exchangerCatalytic converter170-3500C (340-6600F)

LP steam

Sulphur condenser

S liquid Further treatment

130-2000C (270-3900F)

Reaction furnaceFunction Burn 1/3 of the H2S H2S + 3/2 O2 SO2 + H2O + Heat Produce sulphur directly 2H2S + SO2 2H2S + 3/n Sn +Heat Destroy feed contaminants 2NH3 +3/2O2 3H2O +N2

TWO ZONE REACTION FURNANCE2/3rd Acid gas

1/3rd Acid GasSour Gas

Zone 1

Zone 2

AirH2S + 3/2 O2 2H2S + SO2 2NH3 +3/2O2 SO2 + H2O + Heat 2H2S + 3/n Sn +Heat 3H2O +N2

Zone 1 : Combustion chamber Zone 2 : Reaction Chamber

Catalytic Reactions2H2S + SO2COS + H2O CS2 + 2H2O

3/x Sx + 2H2OH2S + CO2 2 H2S + CO2

Catalytic Converter Activated Alumina Catalyst

Sulphur CondenserOperating Limits: above sulphur melting / freezing point 1190C (2460F)

below inlet sulphur dewpoint depends on sulphur vapour content

SuperClaus Section The remaining gases are then passed through three stage of in-line-reheaters, catalytic converters, and condensers with each stage recovering 61%, 22% and 9% of the total sulphur respectively.RHTR1 RHTR 2 RHTR 3 TAIL GAS ANALYZERP HX-1 HX-2 HX-3

CV 1T-1

CV 2T-2

CV 3T-3

HX-4 HX-5

HX-6

CNDS 2

CNDS 3 SULPHUR

CNDS 4 SULPHUR

SULPHUR

Acid Gas

Diagram of Sulphur Recovery UnitHP STEAM (42 Kg/cm2) 1400 OC LP STEAM WASTE HEAT BOILER 322 OC 180 OC REACTION FURNACE

Sour Gas

BFW

IST CONDENSER 208 OC

BFW

232 OC

IST CONVERTER

2ND CONVERTER TAIL GAS TO TGTU 132 OC

AIR BLOWER

HP STEAM IST REHEATER 287 OC

HP STEAM2ND REHEATER LP STEAM 173 OC

HEATED BFW 233 OC

2ND CONDENSER

BFW

FINAL CONDENSER

BFW

SULPHUR YARD

SULPHUR STORAGE YARD

Tail Gas Treating Unit essential to minimize sulphur emissions Sulphur Recovery of 99.9 %.This unit consists of 3 sections Hydrogenation Section Amine absorption and regeneration SectionT-3

TAIL GAS

H2 TO INCINERATION

Co - Mo Hydrogenation Reactor

T-1

Incinerator Section

TO REACTION FURNACE

T-2

AMINE ABSORPTION REGENERATION

The tail gas from the Claus units is heated by superheated HP steam and mixed with hydrogen.

Then passed over a catalyst bed in order to convert any SO2 present in the tail gas back to H2S.This gas is then cooled and passed through an Amine absorber, where H2S is absorbed in MDEA. The rich MDEA thus formed is regenerated in the amine regeneration system inbuilt within the TGTU and returned to the absorber.

The acid gas released is sent back to SRU for Sulphur Recovery.The Tail gas then goes to the Incinerator, where it is burnt off and the flue gas goes to the stack. The main reaction in the hydrogenation reaction is

SO2 + 3H2

H2S + 2H2O

Thank You