Ammonia and urea production involves high-pressure ammonia synthesis, urea synthesis (CO2 + NH3), and corrosive ammonium carbamate/urea solution. Pumps handle high-pressure ammonia, corrosive carbamate, and viscous urea solution. This guide covers pump selection for ammonia and urea fertilizer production.
Ammonia / Urea Pump Services
| Service | Fluid | Temp | Pressure | Key Characteristic | Pump Type |
|---|---|---|---|---|---|
| Ammonia feed (to synthesis loop) | Liquid ammonia (NH3) | -33 to 40°C | 15–30 bar (pump), 150–300 bar (loop) | Very volatile (vapor pressure ~10 bar at 25°C), toxic, corrosive (anhydrous NH3), high pressure, critical, zero leakage | API 610 BB3 multistage (high pressure, 316SS, double seal, low-NPSH) or high-pressure plunger pump |
| CO2 feed (to urea synthesis) | Carbon dioxide (CO2, gas — compressor) | — | 140–250 bar | Gas (compressor, not liquid pump) | Not liquid pump (reciprocating/centrifugal compressor) |
| Urea reactor feed (ammonia + carbamate) | NH3 + ammonium carbamate (NH2COONH4) | 150–200°C | 140–250 bar | Very corrosive (carbamate attacks stainless steel), very high pressure, hot, critical, zero leakage, safety | Special high-pressure pump (duplex/super duplex, 25Cr-22Ni-2Mo, API 610, double casing) — not standard |
| Urea solution (from reactor) | Urea solution (70–80% urea + water + carbamate) | 150–200°C | 140–250 bar (let-down) | Corrosive (carbamate residue), hot, viscous (concentrated), critical, large flow | API 610 OH2 (duplex/super duplex, high temp, corrosion, centerline) or let-down valve |
| Carbamate condenser / recirculation | Ammonium carbamate solution (corrosive) | 150–200°C | 140–250 bar | Extremely corrosive (carbamate = most corrosive in urea plant), very high pressure, hot, critical | Special high-pressure pump (25Cr-22Ni-2Mo super duplex, API 610, double casing) — specialized |
| Urea concentration (evaporator feed) | Urea solution (70% → 95–99%) | 80–140°C (vacuum) | Vacuum–5 bar | Viscous (concentrated urea ~100–1000 cP), hot, corrosive (some), scaling (biuret formation), large flow, low-NPSH (vacuum) | Screw pump or API 610 OH2 (viscous, low-NPSH, jacketed, 316SS/duplex) |
| Urea melt (to prilling/granulation) | Molten urea (99.7%, ~140°C) | 135–145°C (mp 132.7°C) | 2–10 bar | Very viscous (1000–5000 cP at 140°C), hot, solidifies below 132°C, precise (prilling), corrosive (biuret), critical | Screw pump or gear pump (viscous, jacketed, self-priming, precise, 316SS) |
| Ammonia refrigeration (compressor, not pump) | Ammonia refrigerant (gas/liquid) | -33 to 40°C | Variable | Refrigeration cycle (compressor + expansion valve, not liquid pump) | Not liquid pump (ammonia compressor) |
| Ammonia storage transfer | Liquid ammonia (refrigerated or pressurized) | -33°C (refrigerated) or ambient (pressurized) | 1–15 bar | Very volatile, toxic, corrosive, large flow, intermittent (loading), low-NPSH | API 610 OH2 (316SS, double seal, low-NPSH, zero leakage) or vertical submerged pump |
| Urea solution transfer (dilute) | Dilute urea solution (30–50%) | 40–80°C | 2–10 bar | Moderately corrosive, viscous (some), large flow, continuous, non-critical | 316SS centrifugal or OH2 (corrosion, large flow) |
| Wastewater (urea plant) | Wastewater (urea + NH3 + carbamate) | 40–80°C | 2–10 bar | Corrosive (ammonia + carbamate), high COD/N, toxic (ammonia), environmental, large flow | 316SS centrifugal or fluoroplastic (corrosion, zero leakage) |
| Process condensate (stripper feed) | Condensate (NH3 + CO2 + urea) | 100–150°C | 5–20 bar | Corrosive (ammonia + CO2), hot, large flow, continuous, environmental (recovery) | API 610 OH2 (316SS/duplex, high temp, corrosion, large flow) |
| Boiler feed water (BFW) | High-purity BFW (for waste heat boiler) | 100–150°C | 20–50 bar | Very clean, hot, high pressure, large flow, critical (steam generation) | API 610 BB3 multistage (316SS, high pressure, high temp, BFW quality) |
| CIP / flush | Water + dilute acid (flush urea/carbamate) | 60–80°C | 2–10 bar | Intermittent, large flow, corrosive (some), scale removal | 316SS centrifugal (corrosion, large flow, CIP-compatible) |
Critical: Ammonium Carbamate Corrosion (Most Severe)
Ammonium carbamate (NH2COONH4) is the most corrosive fluid in fertilizer production — it attacks standard stainless steel:
- Carbamate corrosion: Carbamate forms in urea reactor (NH3 + CO2 → carbamate → urea). At 150–200°C, 140–250 bar, carbamate is extremely corrosive to 304SS and even 316SS. Use super duplex (25Cr-22Ni-2Mo, e.g., 2RE10, Sandvik SX) or high-alloy austenitic (urea-grade 316L with 0.2% Si max — "urea grade" 316L has controlled silicon to resist carbamate). Passivation with nitric acid (forms protective oxide layer). Oxygen injection (maintains passivation). Monitor corrosion (corrosion coupons, UT). Our urea-grade alloy range handles carbamate.
- High pressure + high temp: Urea synthesis at 140–250 bar, 150–200°C. Use special high-pressure pump (double casing, API 610 BB5-style or specialized). Centerline mounting. High-temp seal (plan 32 flush with clean ammonia/carbamate). Jacketed seal chamber. This is specialized equipment — not standard API 610 OH2. Our high-pressure alloy pumps handle urea synthesis.
- Safety: Ammonia is toxic (IDLH 300 ppm, TLV 25 ppm), carbamate is corrosive. Zero leakage (double mechanical seal or magnetic drive). Gas detection (NH3 sensor). Emergency water shower. PPE (respirator, chemical suit). Ventilation. Secondary containment. Our zero-leakage range prevents ammonia/carbamate exposure.
Critical: Liquid Ammonia (High Vapor Pressure + Toxic + Low NPSH)
- High vapor pressure: Anhydrous ammonia ~10 bar at 25°C, ~15 bar at 40°C. Pump must handle high suction pressure. Low-NPSH impeller (large eye, inducer). Flooded suction (mount below tank). NPSH margin ＞3m. Refrigerated storage (-33°C at 1 bar) reduces vapor pressure but requires low-temp materials (316SS — carbon steel OK for -33°C, but 316SS safer). Pressure relief. Our low-NPSH API 610 range handles liquid ammonia.
- Toxic + zero leakage: Ammonia is toxic and corrosive. Use double mechanical seal (plan 53B barrier) or magnetic drive pump (zero leakage). Gas detection. Emergency scrubber (water). PPE. Our zero-leakage range prevents ammonia release.
- Ammonia corrosion: Anhydrous ammonia is compatible with carbon steel (standard) and 316SS. Aqueous ammonia (ammonium hydroxide) is corrosive to copper, zinc, brass — use steel/316SS. Stress corrosion cracking (SCC) in carbon steel with oxygen + ammonia — use killed steel, stress relief. Our 316SS/killed steel range handles ammonia.
Critical: Urea Melt (Viscous + Solidification + Biuret)
- Viscous + solidification: Molten urea (99.7%) is 1000–5000 cP at 140°C, solidifies at 132.7°C. Use screw pump or internal gear pump (positive displacement, handles high viscosity, self-priming). Jacketed pump (steam/hot oil, maintain 135–145°C — above mp, below 150°C to minimize biuret). Jacketed piping. Heat tracing. Insulation. Pre-heat pump. Flush with steam/hot water before shutdown (don't let urea solidify). Temperature control critical (135–145°C window). Our jacketed PD range handles urea melt.
- Biuret formation: Urea decomposes at ＞150°C: 2 urea → biuret + NH3. Biuret is phytotoxic (damages crops) — must minimize (＜1% for fertilizer grade). Keep temperature ＜150°C. Minimize residence time. Jacketed (precise temp control). Our jacketed range minimizes biuret.
- Precise (prilling): Urea melt to prilling tower requires precise flow (uniform prill size). Positive displacement pump (screw/gear) + VFD + flow meter. Calibration. Our PD pump + meter integration supports prilling.
Critical: Urea Concentration (Vacuum + Viscous + Low NPSH)
- Vacuum evaporation: Urea concentrated 70% → 95–99% under vacuum (80–140°C). NPSH critical (vacuum). Use low-NPSH screw pump or API 610 OH2 (large eye, inducer, flooded suction). Jacketed (maintain temp, prevent crystallization). Viscosity increases with concentration (100 → 1000 cP). Positive displacement for ＞85% urea. Our low-NPSH viscous range handles urea concentration.
Material Compatibility
| Material | Liquid NH3 (25°C, toxic, high VP) | Carbamate (180°C, 200 bar, very corrosive) | Urea melt (140°C, viscous, solidifies) | Dilute urea (60°C, mild) | Wastewater (NH3 + urea, 60°C) |
|---|---|---|---|---|---|
| Carbon steel (killed) | Good (anhydrous NH3 standard) | NOT (carbamate corrosion) | Fair (urea, but check) | Good (dilute, low temp) | Fair (ammonia corrosion) |
| 316SS (standard) | Excellent | Fair (carbamate attacks — need urea grade) | Good | Excellent | Good |
| Urea-grade 316L (low Si) | Excellent | Good (carbamate-resistant with O2 passivation) | Good | Excellent | Good |
| Super duplex (25Cr-22Ni-2Mo) | Excellent | Excellent (carbamate, high pressure) | Good | Excellent | Excellent |
| 2RE10 / Sandvik SX | Excellent | Excellent (specialized for carbamate) | Good | Excellent | Excellent |
| PTFE-lined | Fair (NH3 may permeate) | NOT (high temp ＞100°C) | NOT (high temp) | Good | Good |
| EPDM seals | Fair (NH3 may affect) | NOT (high temp) | NOT (high temp) | Good | Good |
| PTFE/FFKM seals | Excellent | Excellent (high temp + corrosion) | Excellent (high temp) | Excellent | Excellent |
| NBR seals | NOT (NH3 attacks NBR) | NOT | NOT (high temp) | Fair | Fair |
| FKM (Viton) | Fair | NOT (high temp) | NOT (high temp) | Good | Good |
Critical: Liquid ammonia = carbon steel (killed) or 316SS + PTFE/FFKM (NOT NBR) + double seal + low-NPSH + zero leakage + safety. Carbamate = urea-grade 316L (low Si) or super duplex/2RE10 + PTFE/FFKM + high-pressure double casing + O2 passivation + zero leakage. Urea melt = 316SS + jacketed screw/gear (135–145°C) + PTFE/FFKM + prevent solidification + minimize biuret (＜150°C). Dilute urea/wastewater = 316SS + EPDM/PTFE. All = zero leakage + NH3 safety + corrosion monitoring.
Common Problems and Solutions
Problem 1: Carbamate pump corrodes (316SS). Standard 316SS fails in hot carbamate. Solution: use urea-grade 316L (low Si) or super duplex/2RE10 API 610 OH2. O2 injection (passivation). Monitor corrosion. Our urea-grade alloy range handles carbamate.
Problem 2: Ammonia pump leaks (toxic). Seal fails — ammonia gas released. Solution: use double seal or magnetic drive API 610 OH2. Gas detection. Emergency shower. PPE. Our zero-leakage range prevents ammonia release.
Problem 3: Urea melt solidifies in pump. Temperature drops below 132°C — urea solidifies. Solution: jacketed screw pump (maintain 135–145°C). Jacketed piping. Heat tracing. Pre-heat. Flush before shutdown. Our jacketed range prevents solidification.
Problem 4: Biuret exceeds spec (＞150°C). Urea overheats — biuret forms (phytotoxic). Solution: precise temp control (135–145°C). Jacketed pump. Minimize residence time. Monitor biuret (＜1%). Our jacketed range minimizes biuret.
Problem 5: Ammonia pump cavitates (high vapor pressure). 10 bar vapor pressure — NPSH marginal. Solution: low-NPSH API 610 OH2 (large eye, inducer). Flooded suction. NPSH margin ＞3m. Refrigerated storage (lower VP). Our low-NPSH range prevents cavitation.
Selection Summary
- Ammonia feed (high pressure): API 610 BB3 multistage or plunger pump (150–300 bar, 316SS, double seal, low-NPSH, zero leakage)
- Urea reactor/carbamate: Special high-pressure pump (urea-grade 316L or super duplex/2RE10, 140–250 bar, 150–200°C, double casing, O2 passivation)
- Urea solution (from reactor): API 610 OH2 (duplex/super duplex, 150–200°C, corrosion, centerline)
- Urea concentration: Screw pump or OH2 (viscous 100–1000 cP, vacuum, low-NPSH, jacketed, 80–140°C)
- Urea melt (prilling): Screw pump or gear pump (1000–5000 cP, jacketed 135–145°C, precise, 316SS, prevent solidification, minimize biuret)
- Ammonia storage transfer: API 610 OH2 (316SS, double seal, low-NPSH, zero leakage, toxic) or vertical submerged
- Dilute urea: 316SS centrifugal or OH2 (30–50%, 40–80°C, large flow)
- Wastewater: 316SS centrifugal or fluoroplastic (NH3 + carbamate, corrosion, zero leakage)
- Process condensate: API 610 OH2 (316SS/duplex, 100–150°C, NH3 + CO2, large flow)
- BFW: API 610 BB3 multistage (316SS, high pressure, high temp, BFW quality)
- Critical: carbamate = urea-grade 316L/super duplex + high pressure + O2 passivation + zero leakage (most corrosive), ammonia = carbon steel/316SS + PTFE (NOT NBR) + double seal + low-NPSH + toxic safety, urea melt = jacketed screw/gear + 135–145°C + prevent solidification + minimize biuret (＜150°C), concentration = vacuum + low-NPSH + viscous, all = zero leakage + NH3 gas detection + PPE + corrosion monitoring
- Our API 610 OH2, BB3 cover ammonia/urea process; screw and gear cover urea melt; 316SS centrifugal covers dilute/wastewater; magnetic drive covers zero-leakage ammonia. For ammonia/urea pump selection, talk to our chemical engineers with your pressure, temperature, carbamate concentration, and urea grade.