Sinter plant exhaust gas scrubbers remove sulfur dioxide (SO2), particulates, and heavy metals from sintering flue gas. Pumps handle corrosive scrubber liquor, abrasive dust slurry, and recirculating water. This guide covers sinter plant FGD (flue gas desulfurization) pump selection and materials.
Sinter Plant Scrubber Pump Services
| Service | Fluid | pH | Solids | Key Characteristic | Pump Type |
|---|---|---|---|---|---|
| Scrubber liquor recirculation (main) | Limestone slurry (CaCO3) + gypsum (CaSO4·2H2O) + water | 5.5–6.5 | 10–25% solids (limestone + gypsum + fly ash) | Very abrasive (gypsum crystals, fly ash), corrosive (acidic, chloride), large flow, continuous, critical (emissions compliance), scaling (gypsum) | Horizontal slurry pump (hard metal/elastomer lined, large passage, high wear, 316SS/cast iron, A49/A532) |
| Limestone slurry feed (to absorber) | Limestone slurry (CaCO3, 20–40% solids) | 8–9 | 20–40% solids | Abrasive (limestone), settling, moderate flow, continuous, critical (SO2 removal reagent), scaling | Horizontal slurry pump or vertical slurry (hard metal/rubber lined, large passage, abrasive, self-priming) |
| Gypsum slurry (byproduct, to dewatering) | Gypsum slurry (CaSO4·2H2O, 10–30% solids) | 5.5–6.5 | 10–30% solids | Abrasive (gypsum crystals), corrosive (chloride), moderate flow, continuous, valuable byproduct (gypsum board), scaling | Horizontal slurry pump or peristaltic (abrasive, moderate flow, large passage, self-priming) |
| Gypsum dewatering (filter feed) | Gypsum slurry (to vacuum belt filter) | 5.5–6.5 | 20–40% solids | Very abrasive, viscous (high solids), moderate flow, intermittent, high wear, settling | Peristaltic hose pump or screw pump (abrasive, high solids, no impeller, self-priming, NBR hose) |
| Quench water (to gas cooler) | Water (cooling hot flue gas 150→60°C) | 4–6 (acidic from SO2 absorption) | 1–5% (fly ash) | Corrosive (acidic SO2 absorption), hot (60–80°C), large flow, continuous, abrasive (fly ash), scaling | Horizontal slurry pump or 316SS/duplex centrifugal (corrosion + abrasion, large flow, hot, open impeller) |
| Absorber recirculation (spray nozzles) | Scrubber liquor (limestone + gypsum + water) | 5.5–6.5 | 10–20% solids | Abrasive, corrosive, high pressure (spray nozzles 5–15 bar), large flow, continuous, critical (SO2 removal = spray contact), nozzle wear | Horizontal slurry pump (hard metal, high pressure, large flow, abrasion-resistant, A49) |
| Wastewater (from FGD, to treatment) | Wastewater (chloride, heavy metals, suspended solids) | 4–7 | 1–5% solids | Corrosive (high chloride 10,000–50,000 ppm), toxic (heavy metals: Hg, As, Se), moderate flow, continuous, environmental (zero liquid discharge trend) | Duplex/super duplex centrifugal or fluoroplastic (high chloride corrosion, toxic, moderate flow, EPDM/PTFE) |
| Sludge (from wastewater treatment) | Sludge (heavy metal hydroxide + CaSO4) | 8–10 | 5–20% solids | Abrasive, corrosive, viscous, small/moderate flow, intermittent, toxic (heavy metals), settling | Peristaltic hose pump or screw pump (abrasive, viscous, no impeller, self-priming, NBR hose) |
| Makeup water (to scrubber) | Water (process water) | 7–8 | Clean | Large flow, low head, continuous, clean, level control | Horizontal split case or end-suction (water, large flow, low head, cast iron/bronze) |
| Chemical dosing (NaOH, coagulant, flocculant) | NaOH (pH), polymer (flocculant), coagulant | — | — | Corrosive (NaOH), viscous (polymer), shear-sensitive (polymer), precise, small flow, continuous | Diaphragm metering (PTFE, NaOH/coagulant) or peristaltic (polymer, low shear, viscous) |
| Oxidation air (not pump) | Air (to oxidize CaSO3 → CaSO4) | — | — | Gas (blower/compressor, not liquid pump) | Not liquid pump (positive displacement blower or compressor) |
| Electrostatic precipitator (ESP) wash water | Water (washing ESP plates) | 6–8 | 1–10% (fly ash) | Abrasive (fly ash), corrosive (some), intermittent, moderate flow, high pressure (spray) | 316SS centrifugal or slurry (abrasion, moderate flow, high pressure) |
Critical: Abrasion + Corrosion (FGD Slurry)
FGD scrubber liquor is both abrasive and corrosive — material selection is challenging:
- Abrasion (gypsum + limestone + fly ash): Gypsum crystals (CaSO4·2H2O), limestone (CaCO3), and fly ash are abrasive. Use: (1) hard metal (high-chrome white iron A49/A532, 600+ BHN — best for coarse solids), (2) elastomer lined (natural rubber — best for fine solids ＜2mm, but limited to ＜60°C; polyurethane — up to 80°C), (3) large passage (reduce velocity, ＜3 m/s in volute), (4) low speed (wear ∝ speed³ — run 600–1200 RPM). Horizontal slurry pump with replaceable wear liners. Our slurry pumps handle FGD abrasion.
- Corrosion (acidic + chloride): FGD liquor is acidic (pH 5.5–6.5) with high chloride (10,000–50,000 ppm from coal). Use: (1) duplex/super duplex stainless steel (PREN ＞40 — resists chloride pitting), (2) 316SS — only low chloride (＜1000 ppm), (3) rubber lined (corrosion barrier + abrasion), (4) Hastelloy C (best metal, expensive). FGD wastewater (high chloride) = duplex/super duplex or fluoroplastic. Our corrosion/abrasion-resistant pumps handle FGD liquor.
- Combined abrasion-corrosion: The worst case — abrasion removes protective oxide layer, corrosion accelerates. Use: (1) rubber lined (corrosion barrier + abrasion resistance for fine solids), (2) hard metal + corrosion allowance, (3) duplex (corrosion + some abrasion), (4) velocity control (＜3 m/s). Our FGD-specific slurry pumps handle combined wear.
Critical: Gypsum Scaling
- Gypsum scaling: Gypsum (CaSO4·2H2O) can scale on pump internals, piping, nozzles — reduces flow, increases wear. Control: (1) maintain proper solids concentration (10–20% in absorber, not supersaturated), (2) oxidation air (ensure CaSO3 → CaSO4·2H2O — CaSO3 is more scaling), (3) chloride control (high chloride increases gypsum solubility, which reduces scaling but increases corrosion), (4) flush pumps after shutdown, (5) open impeller (less scaling). Our FGD pumps include anti-scaling design features.
Critical: High Pressure Spray (Absorber Nozzles)
- Spray nozzles: SO2 removal depends on gas-liquid contact — spray nozzles require 5–15 bar pressure. Use: (1) high-pressure slurry pump (hard metal, multistage or high head single stage), (2) large passage nozzles (prevent clogging — 10–20mm orifice), (3) abrasion-resistant nozzles (SiC, polyurethane), (4) multiple spray levels (each with dedicated pump). Our high-pressure slurry pumps handle absorber spray duty.
Critical: FGD Wastewater (High Chloride + Heavy Metals)
- Wastewater characteristics: FGD wastewater has high chloride (10,000–50,000 ppm), heavy metals (Hg, As, Se, Cd, Pb), suspended solids, low pH. Very corrosive. Use: (1) duplex/super duplex (PREN ＞40 — chloride pitting resistance), (2) fluoroplastic (excellent corrosion, but limited pressure/temp), (3) titanium (best, expensive), (4) EPDM/PTFE seals. Treatment: chemical precipitation (heavy metals), filtration, biological (selenium), ZLD (zero liquid discharge — trend). Our corrosion-resistant pumps handle FGD wastewater.
- Environmental compliance: FGD wastewater discharge is heavily regulated (Hg, As, Se limits). Proper pump selection prevents leaks (containment). Zero leakage (magnetic drive or double seal) for toxic wastewater. Our systems meet environmental standards.
Material Compatibility
| Material | Scrubber liquor (pH 5.5–6.5, 15% solids, chloride 5000 ppm, 60°C) | Limestone slurry (pH 8–9, 30% solids, ambient) | FGD wastewater (pH 5, chloride 30,000 ppm, heavy metals, 50°C) | Quench water (pH 4–5, 3% fly ash, 70°C) |
|---|---|---|---|---|
| High-chrome white iron (A49) | Excellent (abrasion, check corrosion) | Excellent (abrasion) | Fair (corrosion from high chloride) | Good (abrasion, check acid corrosion) |
| Natural rubber lined | Good (fine solids, ＜60°C, corrosion barrier) | Excellent (abrasion + alkali) | NOT (high chloride may permeate lining at elevated temperature) | Fair (70°C ＞ rubber limit 60°C) |
| Polyurethane (PU) lined | Good (fine/medium solids, ＜80°C) | Good | Fair (check chemical resistance) | Good (up to 80°C) |
| 316SS | Fair (chloride pitting at 5000 ppm) | Good (alkali) | NOT (30,000 ppm chloride pitting) | Fair (acid + chloride) |
| Duplex SS | Good (chloride 5000 ppm, PREN 35–40) | Good | Good (30,000 ppm, check PREN) | Good (acid + chloride) |
| Super duplex | Excellent | Good | Excellent (30,000+ ppm, PREN ＞40) | Excellent |
| Hastelloy C | Excellent (corrosion + some abrasion) | Good | Excellent (best metal) | Excellent |
| PTFE/PFA lined | Fair (abrasion may wear lining) | Good | Excellent (corrosion) | Good (acid, check abrasion) |
| NBR hose (peristaltic) | Good (abrasion + water) | Good | Fair (check chemical) | Good |
| EPDM seals | Good (water, up to 120°C) | Excellent (alkali) | Good | Good (acid water) |
| PTFE seals | Excellent (corrosion) | Excellent | Excellent | Excellent |
Critical: Scrubber liquor (abrasive + corrosive) = hard metal (A49) or rubber/PU lined slurry + EPDM/PTFE + low speed. Limestone slurry = hard metal/rubber lined slurry (abrasive, alkali). FGD wastewater (high chloride + heavy metals) = super duplex/Hastelloy/fluoroplastic + EPDM/PTFE (NOT 316SS). Quench water (acidic + fly ash + hot) = duplex/PU lined slurry + EPDM. Gypsum dewatering = peristaltic (NBR hose, high solids, no impeller). Chemicals = diaphragm metering (NaOH/coagulant) or peristaltic (polymer low shear). All = abrasion-corrosion combined + gypsum scaling control + low speed + replaceable wear parts + environmental compliance.
Common Problems and Solutions
Problem 1: Slurry pump wears in 3 months (abrasion). High-speed pump with gypsum/fly ash. Solution: low-speed hard metal slurry pump (600–1200 RPM, A49). Rubber/PU lined (fine solids). Replaceable liners. Monitor wear. Our low-speed slurry pumps extend life.
Problem 2: FGD wastewater pump corrodes (high chloride). 316SS pump in 30,000 ppm chloride — pitting. Solution: use super duplex/Hastelloy centrifugal or fluoroplastic. EPDM/PTFE seals. Our chloride-resistant pumps handle FGD wastewater.
Problem 3: Gypsum scales in pump/nozzles. Supersaturated gypsum scales. Solution: maintain proper solids (10–20%), oxidation air (CaSO3→CaSO4·2H2O), flush after shutdown, open impeller, large nozzles. Our anti-scaling design prevents gypsum buildup.
Problem 4: Absorber spray pressure low (pump wear). Worn impeller reduces head — poor SO2 removal. Solution: high-pressure hard metal slurry pump, wear monitoring (vibration/performance), spare impeller. Our high-pressure slurry pumps maintain spray pressure.
Problem 5: Polymer dosing ineffective (shear degradation). Gear pump shears flocculant polymer. Solution: use peristaltic pump (low shear). Dilute properly (0.1–0.5%). Age 30–60 min. Our low-shear peristaltic pumps preserve polymer.
Problem 6: Quench pump fails (acid + abrasion + heat). 70°C acidic SO2 water with fly ash. Solution: PU-lined slurry pump (up to 80°C) or duplex centrifugal (corrosion). Open impeller. EPDM seals. Our quench pumps handle acid+abrasion+heat.
Selection Summary
- Scrubber liquor recirculation: Horizontal slurry pump (hard metal A49 or rubber/PU lined, low speed 600–1200 RPM, large passage, 10–25% solids, pH 5.5–6.5, replaceable wear parts)
- Absorber spray (high pressure): Horizontal slurry pump (hard metal, high pressure 5–15 bar, large flow, abrasion-resistant, nozzle-compatible)
- Limestone slurry feed: Horizontal slurry or vertical slurry (hard metal/rubber, 20–40% solids, abrasive, self-priming, pH 8–9)
- Gypsum slurry: Horizontal slurry pump or peristaltic (abrasive, 10–30% solids, large passage, scaling control)
- Gypsum dewatering: Peristaltic hose pump or screw (20–40% solids, no impeller, self-priming, NBR hose)
- Quench water: Slurry pump (PU lined ＜80°C) or duplex centrifugal (acidic SO2, fly ash, 60–80°C, open impeller)
- FGD wastewater: Super duplex/Hastelloy centrifugal or fluoroplastic (high chloride 10,000–50,000 ppm, heavy metals, toxic, EPDM/PTFE, zero leakage)
- Sludge: Peristaltic hose pump or screw (heavy metal sludge, abrasive, viscous, no impeller, self-priming)
- Makeup water: Horizontal split case (clean water, large flow, low head, cast iron/bronze)
- Chemical dosing: Diaphragm metering (NaOH, coagulant, PTFE, precise) or peristaltic (polymer, low shear, viscous)
- ESP wash water: 316SS centrifugal or slurry (fly ash, abrasive, high pressure spray)
- Critical: FGD = abrasion (gypsum/limestone/fly ash) + corrosion (acidic + high chloride) COMBINED → hard metal (A49) or rubber/PU lined slurry + low speed (wear ∝ speed³), high chloride wastewater = super duplex/Hastelloy/fluoroplastic (NOT 316SS), gypsum scaling = oxidation air + solids control + flush, spray = high-pressure slurry + large nozzles, all = replaceable wear parts + environmental compliance (SO2/heavy metals) + material compatibility + reliability (emissions)
- Our horizontal slurry and vertical slurry cover main FGD service; peristaltic covers dewatering/sludge/polymer; duplex/316SS covers wastewater/quench; fluoroplastic covers corrosive wastewater; metering covers chemicals. For sinter plant FGD pump selection, talk to our environmental engineers with your flue gas flow, SO2 concentration, chloride level, and slurry solids.