FIELD: technological processes.
SUBSTANCE: invention relates to a method for reducing the content of sulfur dioxide in a flue gas coming out of a boiler installation with a circulating fluidized bed including a semi-dry scrubber. Method includes the following steps: feeding the first stream of sulfur-containing carbon-containing fuel into a furnace of the boiler; feeding the second stream of absorbent containing calcium carbonate and having a predetermined particle size d50; feeding an oxygen-containing gas to the furnace for fluidizing a bed of particles; burning fuel with oxygen, whereby sulfur in the fuel is oxidized to sulfur dioxide; calcinating calcium carbonate to calcium oxide in the furnace and using a part of calcium oxide to sulfate the first part of sulfur dioxide to calcium sulfate in the furnace; releasing the flue gases containing the second portion of sulfur dioxide, and particles, including particles of calcium oxide trapped by the flue gases, through a flue gas channel from the furnace. Then, separating the first part of the trapped particles, including the first part of the captured calcium oxide particles, from the flue gases in a particle separator with a cutoff size, and returning at least part of the separated particles through a return channel to the furnace. Transporting the second part of the trapped particles, including the second part of the trapped particles of calcium oxide, with the flue gases from the furnace to a semi-dry stage of reducing the sulfur content, located downstream of the furnace, and reducing the sulfur dioxide content in the flue gases in the semi-dry stage of reducing the amount of sulfur. In this case, the predetermined size d50 of absorbent particles containing calcium carbonate is from 10 to 20 mcm and less than 50 % of the cutoff size of the particle separator.
EFFECT: technical result is to create a method that provides an extremely effective and economical reduction in the amount of sulfur dioxide.
10 cl, 2 dwg
