Choosing the Right Pump for Flue Gas Desulphurisation

As new coal-fired power plants come on line to meet the growing demand for electricity in the US and around the world, there is an increasing need to clean plant emissions to meet clean air regulations. Special pumps help to operate these scrubbers efficiently and handle the abrasive slurries used in the flue gas desulphurisation (FGD) process.

Pump selection for FGD

As this limestone slurry needs to be moved efficiently through a complex industrial process, the selection of the right pumps and valves (taking into account their whole life cycle costs and maintenance) is crucial.

Series of TL FGD pump is a single stage single suction horizontal centrifugal pump. It is mainly used as the circulation pump for absorbent tower in FGD applications. It has such features: wide range flowing capacity, high efficiency, high saving power. This series of pump is matched by tight structure X bracket which can save much space. Meanwhile our company develops many kinds of material targeted on the pumps for FGD.

TL FGD Pump

The FGD process begins when the limestone feed (rock) is reduced in size by crushing it in a ball mill and then mixed with water in a slurry supply tank. The slurry (approx. 90% water) is then pumped into the absorption tank. As the consistency of the limestone slurry tends to change, suction conditions can occur which can lead to cavitation and pump failure.

A typical pump solution for this application is to install a hard metal slurry pump to withstand these types of conditions. Hard metal pumps need to be able to withstand the most severe abrasive slurry service and they also need to be designed to be extremely easy to maintain and safe.

Critical to the engineering of the pump are heavy duty bearing frames and shafts, extra thick wall sections and easily replaceable wear parts. Total life cycle cost considerations are critical when specifying pumps for severe operating conditions, such as FGD service. High chrome pumps are ideal due to the corrosive pH of the slurry.

Slurry Pump

The slurry must be pumped from the absorber tank to the top of the spray tower where it is sprayed downwards as a fine mist to react with the upward moving flue gas. With pumping volumes typically in the range of 16,000 to 20,000 gallons of slurry per minute and heads of 65 to 110 feet, rubber lined slurry pumps are the optimal pumping solution.

Again, to meet life cycle cost considerations, pumps should be equipped with large diameter impellers for lower operating speeds and longer wear life, as well as field replaceable rubber liners that can be bolted on for quick maintenance. In a typical coal-fired power plant, two to five pumps will be used in each spray tower.

As the slurry is collected at the bottom of the tower, more rubber lined pumps are required to transfer the slurry to storage tanks, tailings ponds, waste treatment facilities or filter presses. Depending on the type of FGD process, other pump models are available for slurry discharge, pre-scrubber recovery and catch basin applications.