A semi-dry desulfurization system and method for a circulating fluidized bed boiler

Abstract

A semi-dry desulfurization system and method for a circulating fluidized bed boiler belongs to the technical field of flue gas purification. The present invention uses quicklime as raw material to prepare desulfurization agent slurry. The slurry is mixed with boiler bottom slag or circulating ash in the overall boiler system and sent to the furnace for desulfurization, thereby achieving compact integration of the desulfurization system and the boiler. The desulfurization system includes a desulfurization agent slurry preparation system and a desulfurization agent addition system. The desulfurizer prepared using quicklime realizes the preparation of micron-sized desulfurizer particles. Through the rapid mixing of the slurry with the bottom slag or circulating ash, it adheres to the surface of the bottom slag or circulating ash, which can effectively prolong the life of the desulfurization agent in the fluidized bed boiler. Residence time, thereby improving calcium utilization, has the advantage of saving the amount of desulfurizer raw materials. Compared with the existing method of directly injecting desulfurizer into the circulating fluidized bed boiler furnace, the present invention has the advantage of efficiently removing sulfur-containing gases, has a compact structure, and can be easily used in actual industrial processes.

Description

technical field [0001] The invention relates to a method and device for purifying flue gas of combustion equipment, in particular to a semi-dry desulfurization system and method for a circulating fluidized bed boiler, belonging to the technical field of flue gas purification. Background technique [0002] A large number of pollutants (such as sulfur oxides, nitrogen oxides, and dust) produced by combustion equipment have caused great harm to the atmospheric environment and human health. Pollutant removal of coal-fired equipment has been highly valued by the whole society. The trend of global coal consumption increasing year by year is still very obvious, but various countries continue to formulate stricter emission regulations to achieve total emission control. For all coal-fired enterprises, they have or will face more serious investment in pollutant emission reduction, and circulating fluidized bed boilers with clean coal combustion as their advantage will also face the s...

AI Technical Summary

Problems solved by technology

Since the particle size of the limestone desulfurizer sprayed into the combustion chamber of the fluidized bed boiler is relatively large (basically equivalent to the particle size of the circulating fluidized bed material), most of them are particles above 100 μm. After reacting with the sulfur-containing gas, the desulfurization products (mainly CaSO 4 Mainly) the molar volume is larger than that of CaO, which leads to the clogging of the pores on the surface of the particles, which affects the further utilization of the unreacted calcium-based desulfurizer inside, resulting in a relatively low calcium utilization rate

Therefore, in order to achieve higher desulfurization efficiency, its Ca / S must be increased, that is, more calcium-based desulfurizers need to be added to achieve higher desulfurization efficiency, resulting in a large amount of waste of raw materials for calcium-based desulfurizers

However, if a desulfurizer raw material with a finer particle size is used, not only the raw material is expensive, but also because it is difficult to be separated by the existing cyclone separator in the circulating fluidized bed boiler, its residence time in the bed is shortened, and calcium The problem of low utilization

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