Crusher and grinding be used in wet limestone based flue gas desulphurisation
The limestone unloading, storage, crushing shall be common for both units of the station. The limestone shall be received at power plant in trucks and shall be unloaded and stored under covered shed at some convenient place in the power plant. From storage yard, limestone to the FGD area shall be supplied by trucks/ dumpers.
In the FGD area, there shall be two underground hoppers and limestone shall be unloaded from trucks/ dumpers on underground hoppers/ paved area near the hoppers. Adequate space shall be provided for movement of pay loaders/bulldozers to facilitate dropping of limestone into unloading hoppers.
Limestone from unloading hoppers shall be fed to two sets of conveyor belts through two vibrating feeders, one each placed under each unloading hopper,and then to two limestone crushers via pent house. The crushed limestone shall be supplied via belt feeders placed below crusher floor and bucket elevators to the 2 Nos. crushed limestone bulk storage silo.
In case crushed limestone of size (-) 25 mm is supplied to the plant,Limestone crushers shall not be provided and limestone conveyors after pent house shall be directly led to limestone bulk storage silos.
Limestone Grinding, Slurry Preparation and Storage System
The limestone grinding, slurry preparation and storage system shall be common for both units of the station. The crushed limestone from 2 Nos. bulk storage silos shall be supplied to 2×100%capacity wet ball mills(or mtw european trapezium grinding mill) through gravimetric feeders for wet grinding of limestone. The limestone slurry of required fineness available from the wet ball mill system shall be stored in two limestone slurry tanks of total 24 hour requirement of the plant. From limestone slurry tank, the limestone slurry shall be pumped to individual absorber by means of dedicated 2×100% capacity limestone slurry transfer pumps.
Adequate numbers of agitators shall be provided for each limestone slurry tank to ensure consistent concentration of absorbent and to prevent settlement of solids.
