FGD & SCR — density and concentration across the emission-control loop
Coal-fired emission control spans desulfurization (FGD) and denitrification (SCR). On the FGD side, limestone feed slurry, absorber gypsum slurry, AFT (after-filter tank) gypsum density and wastewater solids all need online slurry density; on the SCR side, reducer concentration — urea / AdBlue (32.5 wt%) and liquid ammonia (25 wt%) — drives NOx removal and ammonia slip. Pisonics ultrasonic density meters run across dozens of plants of China's top-5 power groups (Huaneng, Huadian, Datang, China Energy, SPIC) on 100–1000 MW units — non-nuclear, so no Cs-137 licensing or shielding.
Measurement points, by process step
| Process point | Principle | Model |
|---|---|---|
| Absorber inlet — limestone feed slurry | Ultrasonic acoustic impedance | PS7000 |
| Absorber outlet — gypsum slurry | Ultrasonic | PS7000 |
| AFT tank — gypsum density | Ultrasonic / tuning fork | PS7000 / PS7400 |
| FGD wastewater discharge | Ultrasonic / microwave | PS7000 / PS7600 |
| SCR urea / AdBlue reducer concentration | Tuning fork + PT1000 | PS7400 |
| SCR liquid ammonia tank density | Tuning fork, Ex-rated HP | PS7400 |
Related field cases: gypsum slurry density in absorption towers · AFT high-concentration slurry tower · desulfurization wastewater density.
Why FGD slurry is hard
- Limestone / gypsum slurry corrodes wetted parts; chloride pitting risk — select 2205 / Hastelloy / ceramic wetted parts.
- Crystallization scales insertion meters; the flush PS7000 window resists buildup.
- SCR reducer concentration directly drives NOx-removal rate and ammonia slip.
Non-nuclear retrofit
Sealed-source (Cs-137) FGD gauges carry licensing and shielding overhead — retrofit demand is strong. The PS7000 is a drop-in non-nuclear replacement: PS7000 vs Cs-137 · PS7000 vs Berthold nuclear gauge.
Selection help
See the FGD density meter selection guide, or tell us your measurement point for a recommendation.
