Net flue gas monitoring after dry desulphurization (replacement of pre-scattering flue gas meters)
--A unit of Shanghai Waigaoqiao Power Plant

Scene Characterization:

After desulfurization, the flue gas humidity is <5% and the dust concentration is low (<30mg/m³), but contains unreacted limestone fines.
Powder (particle size <5μm).

The original technology pain point:

The front scatterometer is not sensitive enough for fine particles, the lowest detection limit is only 10mg/m³, and the mirror surface is easily damaged by limestone.
Powder adheres, requiring daily back-purging and high downtime.
Damage to probe rods inserted into the flue in less than one year due to corrosion by acidic gases.

Advantages of the dual-detector backscattering scheme:

• Dual-channel signal amplification technology, detection limit as low as 0.1mg/m³, accuracy ±1.5%F.S;
• There are no parts inserted inside the flue, and it has been in stable condition for more than a year.

Application effect: After the renovation, the annual average number of exceeding alarms was reduced from 22 to 0.