Standard Operating Procedure For Sulfuric Acid Plant

STANDARD OPERATING PROCEDURE PLANT START UP 1. Drain out drip acid from the drain valves of tube side (at bottom) and shell side (just above) Hot Heat Exchanger (HHE), Cold Heat Exchanger (CHE) & Economizer. If drip acid comes out of shell side drain the tubes may be damaged. 2. Drain out condensate from the Blow Down Tank. 3. Check that the drain valve situated in front of Plate Heat Exchanger (PHE)1 and the ball valve in front of PHE-2 are closed. 4. Check that the valve over Final Absorption Tower (FAT) Chimney is in fully closed condition for scrubbing of SO2. 5. Manually open the Steam Drum Inlet Water Valve and Export Valve to fully open condition. 6. Start De-mineralized (DM) water pump & Boiler Feed Water (BFW) pump after setting both in ‘ready’ mode from operator console. Check for cooling water circulation in the pumps. 7. Check that the sample taking valve over Acid Circulation Tank (PAT) is fully closed and operate the circulation valve in such a manner that it is slightly open. 8. Switch on Acid Circulation Pump after setting in ‘ready’ mode from operator console and start acid feed to Drying Tower (DT) keeping its inlet valve 50% open, Intermediate Absorption Tower (IAT) keeping its inlet valve 70% open & FAT keeping its inlet valve 50% open and then fully open the circulation valve over PAT. 9. Start scrubbing system by starting scrubbing pump and maintain pH of circulating liquid at 12 with 5% Caustic Soda (NaOH) soln. in scrubbing system. Add NaOH soln. if required from Caustic Preparation Tank if pH falls below 8. 10. Check Sulfur pump for its freeness and Sulfur pipeline for its ‘throughness’ by blowing compressed air. If line is jam, check that steam is going through the jacket (remove condensate if required) and heat the valves by burning Coke Oven gas over them. Clean pit Sulfur temperature to be kept at 130-140OC with elemental Sulfur of 99.5% purity. 11. Manually open air inlet valve over Sulfur Burner & discharge and bypass valves of Economizer to box up the system so that Sulfur Burner temperature does not fall quickly. 12. Switch on Air Blower after setting in ‘ready’ mode from operator console and adjust discharge pressure to 1200 mm WC initially if Sulfur Burner temperature is below 500OC & 1500 mm WC if Sulfur Burner temperature is around 700OC. 13. Set Sulfur gun discharge valve at 20% open if Sulfur Burner temperature is below 500OC or 10% open if Sulfur Burner temperature is around 700OC and switch on the Sulfur Feed Pump after setting in ‘ready’

mode from operator console. Close the drain valve if any Sulfur is coming from the drain line. 14. Check from the peep hole of Sulfur Burner for proper spray and flame of Sulfur. 15. The plant should be run at low production at first and then raised in steps.

PLANT OPERATION 1. Increase first the Sulfur slowly till temperature reaches around 750 OC and then the air slowly so that Converter 1st stage inlet temperature is around 430OC. This is to be done by adjusting the Waste Heat Boiler (WHB) – 1 ‘shut off’ (FCV 0230) and by pass valves. 2. Adjust gas ducting valves in such a manner that the Converter temperature in the various stages is as follows after 1st stage conversion: STAG INLET TAG NO. OUTLET TAG NO. E TEMPERATURE TEMPERATURE 1ST 430OC TIA 0403 615OC TIA 0407 ND O O 2 435 C TIA 0402 508 C TIA 0408 RD O O 3 425 C TIA 0409 450 C TIA 0412 4TH 425OC TIA 0413 439OC TIA 0404 TH O O 5 425 C TIA 0405 426 C TIA 0406 3. Check the concentration of acid in the Acid Recirculation Tank (PAT) so that it is around 98.5% by either adding fresh conc. Sulfuric Acid from the Storage Tanks or adding dilution water by regulating Rota meter valve. 4. When the temperature of circulating acid reaches 60 OC start Cooling Water (CW) Pump and supply cooling water to the PHE’s. 5. Norms of other critical parameters is as follows: TAG PARAMETER NORM TAG PARAMETER NORM O Sulfur Melter 125-135 OC 0401 Hot Gas Filter Inlet 550 C Temperature Temp. (max) Pure Pit Level 1.0-1.7 m 0510 Acid Circulation Tank 1.10-1.30 m Level L010 Clean Pit Level 0.8-1.6 m Acid Circulation Tank 80-90 OC 4 Temp. T010 Clean Pit Temperature 130-140 OC 0508 Acid Pump Load (max) 135 amp 4 0306 Boiler Steam Pressure 4.55.5 0509 Acid Concentration 98.5% 2 kg/cm 0101 Air Pressure (max) 4000 mm 0515 Acid Inlet 60-75 OC WC Temperature(FAT) 0501 Air Flow (max) 15000 m3/hr 0504 DT Acid Outlet 60-80 OC

Blower Current 0202 0313 0301 0304 0327 0305 0306

18-32 amp

Sulfur Burner 800-980 OC Temperature Sulfur Burner 800-980 OC Temperature DM Water Level 700-2700 mm Deaerator Water 600-750 Level mm Deaerator Water Temp. Steam Drum Water 250-300 Level mm Steam Drum Pressure 8-10 kg/cm2

0417 0418 0505 0517

0506

Temperature DT Gas Inlet Temperature DT Gas Outlet Temperature IAT Gas Inlet 160-220OC Temperature IAT Gas Outlet Temperature IAT Acid Outlet Temperature FAT Gas Inlet 180-250OC Temperature FAT Gas Outlet Temperature FAT AcidOutlet Temperature Cooling Water Outlet Temp. Cooling Water Inlet pH around 7

Steam Drum Inlet 180-240 OC 1101 Temp. Boiler FW 200-240 OC Temperature Boiler Inlet Water 90-100 OC Condensate Blow around 7 Temp. Down pH 0312 Boiler Outlet 340-370 OC P035 Economizer Inlet Water Temperature 3 Pr. 6. Check that all the interlocks are working. 7. In case of sudden stoppages of blower, on re-starting purge the whole system with dry air from blower for 5 minutes. 8. Monitor pH levels in Cooling Water outlet and Boiler Feed Water outlet/Economizer and check that it lies around 7 so as to avoid Hydrogen formation due to corrosive action of dilute H2SO4. 0306 A T035 3 0327

PLANT SHUT DOWN 1. Stop Sulfur pump and drain the Sulfur line on pump side and gun side & check whether any liquid Sulfur is at the bottom of Sulfur Burner through peep hole. 2. Run the Blower till all the Sulfur inside the Sulfur Burner has got burnt for at least 10 min. 3. Blow air in Sulfur line to clean pipeline from Sulfur Burner to Clean Pit and ensure that air comes out from the bypass line in Clean Pit. 4. Stop the Air Blower. 5. Stop the dilution water in the Acid Recirculation Tank. 6. Check that steam is going in the Sulfur jacket line and Sulfur Pump.

SAFETY PRECAUTIONS 1. Do not tamper or bypass safety devices and controls. 2. Mandatory PPE’s – Safety helmet and Safety shoes are a must for entering the plant. 3. Specific PPE’s – PVC Suit, Face Shield, Rubber Hand gloves and Gum boots with PVC Pant over the boot are to be worn while near the Acid Recirculation Tank. 4. Unauthorized entry within the plant premises is strictly prohibited. 5. Employees must remain in their specific work zones. 6. Sitting or resting near Acid Recirculation Tank is strictly prohibited. 7. Match/lighters or other means of causing sparks/flames like naked lights are not to be used. 8. Smoking within the plant premises is strictly prohibited. 9. Cover acid pipeline flanges so that leakage may not cause acid spray. 10. Avoid contact of Sulfur, Sulfuric acid, Sulfur dioxide, Sulfur trioxide, Caustic Soda, Tri Sodium Phosphate, Hydrazine and Vanadium Pent oxide catalyst with eyes, skin or clothing. 11. Keep water and steam available near Sulfur Burner at all times. 12. Do the specified job in the minimum possible time near running equipments; don’t loiter. 13. Walking on pipelines or drain covers is prohibited. 14. In case of emergency reach the Assembly Point.

DO’S

DON’TS

Always add Sulfuric acid to water. Always add Caustic Soda to water. Always use spark resistant tools while handling solid Sulfur.

Never add water to Sulfuric acid. Never add water to Caustic Soda. Don’t come near Sulfur Melter or Pits as a hazardous amount of H2S is produced. Don’t come near burning Sulfur as a hazardous amount of SO2 is produced. Don’t remove solidified Sulfur from skin. Immerse in cold water for 20

Always use steam to snuff out fire in molten Sulfur in closed spaces. Use fine water spray to snuff out fire in solid Sulfur piles.

Cordon off the area in case of leakages.

min. Don’t operate electric switch/start vehicles.