Sour Water Pump: H2S and Ammonia-Laden Wastewater Handling

Sour water pumps handle H2S and ammonia-laden wastewater in refineries and gas processing plants, transporting corrosive, toxic, and abrasive water to stripping and treatment. These pumps require corrosion-resistant materials, reliable sealing for toxic H2S, and robust construction for solids-laden service. This guide covers sour water pump selection, corrosion management, stripping process, and safety considerations.

Sour Water System Overview

Critical: Sour Water Properties and Corrosion

Critical: Sour water is one of the most corrosive services in refineries. The combination of H2S + NH3 forms ammonium bisulfide (NH4HS), which is highly corrosive to carbon steel at high velocity and temperature. Pump material: 316SS for moderate service, duplex (2205) for high chloride/high temp. Carbon steel only for low velocity (＜1.5 m/s) and low temp. Our 316SS pumps and duplex options handle sour water.

Critical: Pump Type Selection

Critical: For sour water feed pumps (the most common and critical), API 610 OH2 with 316SS or duplex trim is standard. For high-chloride or high-temperature service, duplex (2205) is required (316SS may pit). Seals: API 682 dual mechanical seal with barrier fluid (Plan 53/54) — H2S is toxic and flammable, zero leakage mandatory. Our API 610 pumps offer 316SS/duplex configurations and API 682 dual seals.

Critical: H2S Safety and Sealing

• H2S hazards: H2S is toxic (IDLH 100 ppm, immediate danger to life), flammable (LEL 4.3%), and corrosive. Sour water releases H2S gas when pressure drops or temperature rises. Pump seals must contain H2S.
• Seal selection: API 682 dual mechanical seal (tandem or double) with barrier fluid (Plan 53A/B/C or Plan 54). Barrier fluid (e.g., propylene glycol or clean oil) at higher pressure than process — prevents H2S leakage to atmosphere. Single seals NOT recommended for sour water (H2S leak = safety hazard). Our pumps use API 682 dual seals.
• Gas detection: H2S detectors around pump area. Alarm at 10 ppm, evacuation at 20 ppm. Ventilation. Proper PPE (breathing apparatus for maintenance). Our systems include gas detection integration.
• Degassing: Sour water drum allows H2S to degas before pump. Pump suction from liquid phase (not gas). Proper NPSH (H2S vapor pressure). Our systems include proper degassing.

Critical: Sour Water Stripping Process

• Goal: Remove H2S and NH3 from sour water before discharge or reuse. Stripped water typically has ＜50 ppm H2S and ＜100 ppm NH3.
• Process: (1) Sour water collected in drum, (2) pumped to stripper (feed pump), (3) steam stripping (reboiler 100–120°C) drives off H2S and NH3, (4) overhead acid gas (H2S + NH3) to Claus unit (sulfur recovery), (5) bottoms (treated water) to wastewater treatment or reuse.
• Pumps: (1) Feed pump — sour water, corrosive, (2) reboiler pump — hot, corrosive, (3) bottoms pump — cleaner, lower corrosion. Our pumps cover all three.

Critical: Common Problems

• Problem 1: Severe corrosion (NH4HS). H2S + NH3 → ammonium bisulfide → rapid corrosion of carbon steel (especially high velocity/temp). Solution: 316SS or duplex pump, velocity control (＜3 m/s for 316SS, ＜5 m/s for duplex), amine/filtration, corrosion inhibitor. Our pumps use corrosion-resistant materials.
• Problem 2: H2S seal leak (safety). Seal failure → H2S release → toxic exposure, fire. Solution: API 682 dual seal with barrier fluid, gas detection, proper seal material,定期 maintenance, spare seal. Our pumps use reliable dual seals.
• Problem 3: Chloride pitting (desalter water). Chlorides from crude desalter → pitting/crevice corrosion in 316SS. Solution: duplex (2205) for high chloride, proper velocity, corrosion inhibitor,定期 inspection. Our duplex pumps handle chlorides.
• Problem 4: Solids erosion (scale/corrosion products). Solids in sour water → erosion-corrosion → pump failure. Solution: 316SS with hardened trim, velocity control, filtration (upstream),定期 inspection. Our pumps use hardened trim.
• Problem 5: Reboiler pump high-temp failure. 100–120°C + corrosive → seal/casing failure. Solution: duplex pump, high-temp design, API 682 high-temp seals with Plan 32 (cool flush), proper cooling. Our high-temp pumps handle reboiler service.
• Problem 6: Cavitation (H2S vapor pressure). H2S increases vapor pressure → cavitation → damage. Solution: low NPSHr pump, flooded suction, degassing drum, proper suction piping, temp control. Our pumps have low NPSHr.

Selection Summary

1. Sour water feed (to stripper): API 610 OH2 (316SS or duplex trim, 30–80°C, 10–200 m³/h, 5–20 bar, API 682 dual seal for H2S)
2. High-pressure feed (＞20 bar): API 610 BB2 or multistage (316SS/duplex)
3. Reboiler circulation (100–120°C): API 610 OH2 (duplex 2205, high-temp design, API 682 high-temp dual seal)
4. Stripper bottoms (treated water): 316SS end-suction or carbon steel (cleaner, lower corrosion)
5. Sludge/solids: Peristaltic (natural rubber/EPDM, handles solids, no clog, self-priming)
6. Sump/pit drainage: Vertical sump or submersible (316SS/duplex, submerged)
7. Neutralization dosing: Diaphragm metering (PTFE, ±1%, acid/base)
8. Critical: sour water = EXTREME CORROSION (H2S+NH3 → NH4HS, 316SS or duplex, velocity control) + H2S SAFETY (API 682 dual seal, gas detection, zero leakage, toxic/flammable) + HIGH TEMP (reboiler 100–120°C → duplex) + CHLORIDE PITTING (desalter → duplex 2205) + SOLIDS EROSION (hardened trim, filtration), all = environmental compliance + worker safety + equipment reliability
9. Our API 610 OH2, BB2, 316SS pumps, peristaltic pumps, and metering pumps cover sour water systems. For sour water pump selection, talk to our oil & gas engineers with your H2S/NH3 content, temperature, chloride, flow, and pressure.