Acetic acid and PTA (purified terephthalic acid) production involves highly corrosive acetic acid solvent, bromide catalyst, and high-temperature oxidation. Pumps must handle acetic acid corrosion, bromide pitting, and abrasive PTA crystals. This guide covers pump selection for acetic acid and PTA manufacturing.
Acetic Acid / PTA Pump Services
| Service | Fluid | Temp | Key Characteristic | Pump Type |
|---|---|---|---|---|
| Acetic acid feed (to oxidizer) | Acetic acid (solvent, 80–95%) | Ambient–80°C | Corrosive (acetic acid), flammable (glacial), precise, large flow, continuous | 316SS centrifugal or fluoroplastic (corrosion, zero leakage) |
| Oxidizer feed (p-xylene + acetic acid + catalyst) | p-xylene + acetic acid + Co/Mn/Br catalyst | 80–150°C (feed), 190–210°C (oxidizer) | Corrosive (acetic acid + bromide), flammable, abrasive (catalyst), high pressure, critical | 316SS/duplex centrifugal or API 610 OH2 (alloy, high temp, corrosion) |
| Oxidizer recirculation | Reaction mixture (acetic acid + PTA + catalyst + gas) | 190–210°C | Very corrosive (hot acetic acid + bromide), abrasive (PTA crystals), multiphase, high pressure, critical | API 610 OH2 (duplex/super duplex, high temp, corrosion, large passage) |
| Crystallizer feed/circulation | PTA slurry (acetic acid + PTA crystals) | 100–200°C (cooling cascade) | Abrasive (PTA crystals), corrosive (acetic acid), viscous (slurry), large flow, continuous, shear-sensitive (crystal size) | API 610 OH2 (duplex, large passage, low shear) or slurry pump (high solids) |
| PTA slurry transfer (to centrifuge) | PTA crystal slurry (30–50% solids in acetic acid) | 80–150°C | Very abrasive (PTA crystals), corrosive (acetic acid), viscous, large flow, continuous, settling | Horizontal slurry pump (hardened, large passage) or screw pump (gentle, large passage) |
| Centrifuge/filter feed | PTA slurry (to separation) | 80–150°C | Abrasive, corrosive, moderate pressure, precise, large flow | Slurry pump or OH2 (duplex, large passage) |
| Mother liquor (acetic acid + catalyst) | Spent acetic acid + dissolved catalyst (recycle) | 80–150°C | Corrosive (acetic acid + bromide), abrasive (fine PTA), valuable (catalyst recovery), large flow, continuous | 316SS/duplex centrifugal (corrosion, large flow) or fluoroplastic (high corrosion) |
| Acetic acid recovery (distillation) | Acetic acid (recovered, clean) | 100–120°C (distillation) | Corrosive (hot acetic acid), volatile, valuable (recovery), large flow, continuous | 316SS centrifugal or OH2 (316SS, high temp, corrosion) |
| PTA drying feed (wet cake) | Wet PTA cake (5–15% acetic acid, paste-like) | 80–120°C | Very abrasive, viscous/pasty, corrosive (residual acid), small/moderate flow, shear-sensitive | Screw pump or peristaltic (pasty, large passage, gentle, abrasive-resistant) |
| PTA product transfer (dry) | Dry PTA powder (pneumatic, not liquid) | Ambient | Solid (not liquid pump) | Not liquid pump (pneumatic conveying / rotary valve) |
| Hydrogenation feed (purification) | PTA solution (in water, + H2) | 250–280°C | Very hot, high pressure (70–100 bar), corrosive (hot water + residual acid), critical, hydrogen | API 610 BB3 multistage (316SS/duplex, high pressure, high temp, NACE) |
| Catalyst (Co/Mn/Br) dosing | Cobalt acetate, manganese acetate, HBr (catalyst) | Ambient–80°C | Corrosive (HBr, acetic acid), precise (stoichiometric), small flow, valuable, toxic (bromine) | Diaphragm metering (PTFE, precise, zero leakage, corrosion-resistant) |
| Bromine / HBr handling | Bromine (Br2) or hydrobromic acid (HBr) | Ambient–80°C | Very corrosive (bromine attacks most metals), toxic, fuming, precise, small flow, safety-critical | Fluoroplastic pump (PTFE/PFA, only material for bromine) or PTFE metering (zero leakage) |
| CIP (clean-in-place) | NaOH + water + acetic acid rinse | 60–85°C | Corrosive, hot, intermittent, PTA residue (abrasive) | 316SS centrifugal (corrosion, large flow, CIP-compatible) |
| Wastewater (acetic acid-laden) | Wastewater (dilute acetic acid + bromide + PTA) | Ambient–60°C | Corrosive (acetic acid, bromide), high COD, environmental, large flow | 316SS centrifugal or fluoroplastic (corrosion) |
Critical: Acetic Acid Corrosion + Bromide Pitting
Acetic acid + bromide at high temperature is one of the most corrosive combinations in chemical processing:
- Acetic acid corrosion: Acetic acid (especially ＞80%, ＞80°C) corrodes carbon steel and even 304SS. Use 316SS (standard for acetic acid up to ~100°C), 317SS (higher molybdenum, better for hot acetic acid), or duplex/super duplex (best for acetic acid + bromide). 316SS is minimum — carbon steel = NOT for acetic acid. Check concentration + temperature (acetic acid corrosion increases with temp). Our 316SS/duplex range handles acetic acid.
- Bromide pitting: Bromide (Br⁻) causes pitting and crevice corrosion in 316SS (similar to chloride, but more aggressive). Use super duplex (25% Cr, 7% Ni, 4% Mo, PREN ＞40) or alloy 825/625 for high bromide. 316SS = risk at high bromide + high temp. Upgrade wetted parts. Monitor pitting (UT inspection). Our super duplex/alloy range handles bromide.
- Hot acetic acid + bromide (oxidizer): 190–210°C acetic acid + bromide = extremely corrosive. Use super duplex or alloy 825/625. High-temp mechanical seal (plan 32 flush with cool acetic acid). Jacketed seal chamber. API 610 OH2 with alloy construction. Our high-temp corrosion-resistant range handles oxidizer service.
Critical: PTA Crystal Slurry (Abrasive + Shear-Sensitive)
- Abrasive PTA crystals: PTA (terephthalic acid) crystals are abrasive (10–50% solids). Use hardened materials: duplex or super duplex wetted, tungsten carbide or silicon carbide seal faces, hardened shaft. Large passage (reduce velocity). Flush with clean mother liquor (seal plan 32). Strainer upstream. For high solids (＞30%): horizontal slurry pump (rubber-lined or hardened metal, recessed impeller). For moderate solids: API 610 OH2 with duplex. Our abrasive-resistant range handles PTA slurry.
- Shear-sensitive crystals: PTA crystal size affects filtration and product quality — high shear breaks crystals. Use low-shear pump: screw pump (gentle, positive displacement) or large-passage API 610 OH2 (low rotor speed). AVOID gear pump (high shear) for crystal slurry. Low rotor speed. Large passage. Our low-shear range preserves PTA crystal size.
- Settling: PTA crystals settle — use large suction, velocity ＞1.5 m/s in piping, continuous agitation in tank, flush after batch. Peristaltic (no valves to clog) for high solids. Our slurry design resists settling.
Critical: Bromine Handling (PTFE Only)
- Bromine (Br2): Elemental bromine is extremely corrosive — attacks most metals (including 316SS, titanium), fuming, toxic. Use fluoroplastic pump (PTFE/PFA lined — the only reliable material for bromine). PTFE diaphragm metering for dosing. Zero leakage (double containment). Fume hood / closed system. PPE (respirator, chemical suit). Emergency shower. Our PTFE-lined range handles bromine safely.
- HBr (hydrobromic acid): HBr is corrosive (similar to HCl but more aggressive). Use PTFE-lined or alloy (Hastelloy C). PTFE diaphragm metering. Zero leakage. Our corrosion-resistant range handles HBr.
Critical: High-Pressure Hydrogenation (250–280°C, 70–100 bar)
- High pressure + high temp: PTA purification (hydrogenation of 4-CBA impurity) uses 250–280°C, 70–100 bar, hydrogen. Use API 610 BB3 multistage pump (4–8 stages, 316SS/super duplex, high pressure, high temp, NACE MR0175 for H2). Centerline mounting. High-temp seal (plan 32 flush, plan 53B barrier). Hydrogen embrittlement resistance (NACE). Our high-pressure multistage range handles PTA hydrogenation.
Material Compatibility
| Material | Acetic acid (80°C, 90%) | Hot acetic acid + Br (200°C, oxidizer) | PTA slurry (120°C, 40% solids) | Bromine (ambient, Br2) | CIP NaOH (80°C) |
|---|---|---|---|---|---|
| Carbon steel | NOT (acetic acid corrosion) | NOT | NOT | NOT | NOT |
| 304SS | Fair (dilute, low temp) | NOT (pitting) | Fair (abrasion) | NOT | Good |
| 316SS | Good (standard, up to 100°C) | Fair (Br pitting risk) | Good (abrasion) | NOT (Br attacks) | Excellent |
| 317SS | Good (higher Mo, hot acid) | Fair (Br risk) | Good | NOT | Excellent |
| Duplex SS | Excellent | Good (moderate Br) | Excellent (abrasion + corrosion) | NOT | Good |
| Super duplex | Excellent | Excellent (high Br, PREN ＞40) | Excellent | Fair (Br risk) | Good |
| Alloy 825/625 | Excellent | Excellent (Br + hot acid) | Good | Fair | Good |
| PTFE/PFA lined | Excellent | Excellent | Fair (abrasion) | Excellent (only for Br2) | Good |
| Tungsten carbide (seal) | Good | Good | Excellent (abrasion) | Good | Good |
| Silicon carbide (seal) | Excellent | Excellent | Good (abrasion, brittle) | Excellent | Excellent |
| EPDM seals | Good (acetic acid) | NOT (high temp) | Good | NOT (Br) | Excellent |
| PTFE/FFKM seals | Excellent | Excellent | Excellent | Excellent | Excellent |
| FKM (Viton) | Fair (acetic acid may affect) | NOT (high temp) | Good | NOT (Br) | Good |
Critical: Acetic acid = 316SS minimum (317SS/duplex for hot), EPDM/PTFE seals. Hot acetic acid + Br = super duplex/alloy 825 + PTFE/FFKM. PTA slurry = duplex/super duplex + tungsten carbide + large passage + low shear (screw/slurry pump). Bromine = PTFE/PFA lined ONLY (zero leakage). Hydrogenation = BB3 multistage + super duplex + NACE. All = zero leakage + CIP + corrosion monitoring.
Common Problems and Solutions
Problem 1: Acetic acid pump corrodes (316SS pitting). 316SS pump in hot acetic acid + bromide — pitting. Solution: upgrade to super duplex or alloy 825 centrifugal. PTFE/FFKM seals. Monitor. Our super duplex range handles acetic acid + bromide.
Problem 2: PTA slurry pump wears (crystal abrasion). PTA crystals erode pump. Solution: use duplex/super duplex API 610 OH2 (large passage) or slurry pump (＞30% solids). Tungsten carbide seal. Plan 32 flush. Low shear (preserve crystal size). Our abrasive-resistant range handles PTA slurry.
Problem 3: Bromine pump fails (metal corrosion). 316SS pump for bromine — rapid corrosion. Solution: use PTFE/PFA-lined fluoroplastic pump (only reliable material). Zero leakage. Closed system. Our PTFE-lined range handles bromine.
Problem 4: PTA crystal size too small (high shear). Gear pump breaks PTA crystals — poor filtration. Solution: use screw pump (low shear, gentle) or large-passage OH2 (low speed). AVOID gear pump. Our low-shear range preserves crystal size.
Problem 5: Hydrogenation pump fails (high pressure + H2). 100 bar, 280°C, H2 — casing/seal failure. Solution: use API 610 BB3 multistage (super duplex, NACE, high temp seal). Centerline. Our high-pressure range handles PTA hydrogenation.
Selection Summary
- Acetic acid feed: 316SS centrifugal or fluoroplastic (corrosion, zero leakage, 80–95%, ambient–80°C)
- Oxidizer feed/recirc: API 610 OH2 (super duplex/alloy, 190–210°C, acetic acid + Br, high pressure, large passage)
- Crystallizer: API 610 OH2 (duplex, large passage, low shear, 100–200°C) or slurry pump
- PTA slurry transfer: Horizontal slurry pump or screw (30–50% solids, abrasive, gentle, large passage, 80–150°C)
- Centrifuge/filter feed: Slurry pump or OH2 (duplex, large passage, abrasive)
- Mother liquor: 316SS/duplex centrifugal or fluoroplastic (acetic acid + catalyst, large flow, recovery)
- Acetic acid recovery: 316SS centrifugal or OH2 (316SS/317SS, 100–120°C, corrosion)
- Wet cake (dryer feed): Screw pump or peristaltic (pasty, abrasive, gentle, large passage)
- Hydrogenation: API 610 BB3 multistage (super duplex, 250–280°C, 70–100 bar, H2, NACE)
- Catalyst dosing: Diaphragm metering (PTFE, precise, zero leakage, Co/Mn/Br)
- Bromine/HBr: Fluoroplastic pump (PTFE/PFA, ONLY for Br2, zero leakage, toxic) or PTFE metering
- CIP: 316SS centrifugal (corrosion, large flow, 60–85°C, PTA residue)
- Critical: acetic acid = 316SS minimum + EPDM/PTFE (NO carbon steel), hot acid + Br = super duplex/alloy 825 + PTFE/FFKM, PTA slurry = duplex + tungsten carbide + low shear (screw/slurry) + large passage, bromine = PTFE/PFA ONLY + zero leakage + safety, hydrogenation = BB3 multistage + super duplex + NACE, all = zero leakage + CIP + corrosion monitoring
- Our 316SS centrifugal, API 610 OH2, BB3 cover process; slurry and screw cover PTA slurry; fluoroplastic covers bromine; metering covers catalyst. For acetic acid/PTA pump selection, talk to our chemical engineers with your acid concentration, bromide level, PTA solids, and operating temp.