Several methods exist, one of the most popular of which is to ‘scrub’ the gas within an absorber tower. This process commonly pumps exhaust gas through a shower of limestone, which combines with the sulphur dioxide to withdraw it from the exhaust gasses.
Throughout the process, the limestone slurry must be measured and controlled to ensure its correct density. This is commonly measured at inlet and during recirculation.
Challenge
Attempts at using by-pass loops to slow the flow rate led to additional leak points within the piping, causing further aggravation. The company was unhappy with the mass flow meters and needed an alternative technology that would be insensitive to the flow rate but still give the accuracy it required.
solution
The sensors work by measuring the attenuation of an ultrasonics signal though the fluid to determine the density of the slurry in terms of percent undissolved solids. The trial solution was successful, and the plant has since replaced further mass flow meters with the MSM400 controller and pipe sensors.
Key Features: MSM400
- Provides continuous measurement of sludge or slurry density
- 4–20 mA / HART output signal of measured value
- Gives a bright and clear indication of the measured value in poor light conditions
- Choice of sensors for tank insertion or pipeline sensors for in-line density measurement
