Wet flue gas desulfurization (WFGD) is the mainstream desulfurization process in large-scale thermal power, steel, and waste-incineration. Multiple concentration / density measurement points exist; conditions vary widely between points and 'one model fits all' is unrealistic. This guide breaks it down point-by-point.
FGD Density Meter Selection Guide: Complete Point-by-Point
Six core measurement points in a power-plant FGD system have completely different requirements. This guide breaks them down point-by-point with recommended models, materials, and installation notes.
Steps
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Point 1: Limestone slurry tank / prep tank discharge
Conditions: solids 20~30%, ≤ 60°C, pH 8~9, intermittent agitation. Recommended PS7400 (PTFE-coated + 316L) or PS7600 microwave. PS7400 excels at scale resistance; PS7600 is dielectric-sensitive to water and good for moisture monitoring. -
Point 2: Absorber gypsum slurry main
Conditions: solids 15~25%, 50~80°C, dense bubbles from forced oxidation, pH 5~6. Strongly recommended PS7000 — Chirp algorithm is bubble-immune. Secondary: PS7300 DP (cost-effective for large bore). DO NOT choose plain tuning fork — readings distort with bubbles. -
Point 3: Gypsum discharge pump outlet
Conditions: solids 50~60% (saturated), 50~70°C, oxidation foam. Recommended PS7000 (preferred) or PS7500 Na22 nuclear (extreme conditions). DP usable but accuracy-limited. -
Point 4: FGD wastewater discharge
Conditions: high chloride (Cl⁻ > 20,000 mg/L), heavy metals, 40~50°C, strong corrosion. Recommended PS7010 clamp-on (no wetted parts) or PS7400 with titanium / Hastelloy fork. Standard 316L wetted parts are NOT acceptable — chloride pitting corrosion. -
Point 5: Ammonia / urea solution (SCR reducer)
Conditions: 20% ammonia or 40% urea, ambient. Recommended PS7400 (mid-accuracy sufficient) or PS7100 spectroscopy (multi-component high-accuracy). Online concentration to DCS enables closed-loop reducer dosing. -
Point 6: AFT multifunction tower / high-concentration recirculation slurry
Conditions: solids 40~50%, 60~80°C, high scaling. Preferred PS7000 ultrasonic; for budget-no-object highest-accuracy, PS7500 Na22 nuclear.