The desulfurization process of Circulating Fluidized Bed Boiler
Circulating fluidized bed (CFB) combustion technology is one of the most efficient technologies for power generation. Compared to pulverized coal combustion, CFB combustion offers several advantages, including lower operating costs, carbon dioxide emission reduction, and the ability to burn a wide variety of fuels or co-fuels. CFB boilers also exhibit the highest efficiency in meetings desulfurization regulations. In a CFB boiler combustion process, limestone and dolomite are added to the furnace to absorb sulfur dioxide generated during the burning process and convert it to calcium sulfate. The calcium sulfate is collected by a wet scrubber and then sent to a storage facility for later disposal or use as a soilconditioner [1]. The following sections will explain the desulfurization process in more details.
The desulfurization process involves adding limestone or dolomite, which is calcium and magnesium carbonate, to the furnace before combustion takes place. The material is mixed with the coal and air in the turbine and heated when burning takes place. The heat causes a chemical reaction between the limestone and the sulfur in the flue gas, forming calcium sulfate. The sulfur compounds are then removed from the flue gas and sent to a storage facility for later disposal or use as a soil conditioner.
The desulfurization and ash removal process begins before the burning process. During the preparation and storage of the coal, any impurities are removed, including ash and stones, by sieving. This process also reduces the amount of sulfur in the air because the impurities are collected and stored. The coal is also treated with limestone or dolomite before burning to reduce sulfur dioxide emissions.
The desulfurization process continues during the actual combustion of the fuel in the CFB boilers. During combustion, calcium carbonate reacts with the sulfur dioxide in the flue gas and forms calcium sulfate. The calcium sulfate is then removed from the flue gas before it is released into the atmosphere. The wet scrubber collects the calcium sulfate, which is then stored and later used as a soil conditioner.
The last part of the process involves controlling the further emission of sulfur dioxide. Certain chemicals are added to the flue gas to further react with sulfur dioxide and form sulfuric acid. The sulfuric acid is then removed through the wet scrubber. The amount of sulfur dioxide in the air is then regulated in order to meet environmental regulations.
In conclusion, desulfurization of CFB boilers is an important process that needs to be performed properly in order to meet environmental regulations and ensure a clean burning process. The process begins with the preparation and storage of the coal and the addition of limestone or dolomite to reduce sulfur dioxide emissions. During combustion, calcium carbonate reacts with sulfur dioxide and forms calcium sulfate. The calcium sulfate is then removed from the flue gas and stored. Finally, additional chemicals may be added to the flue gas in order to further react with sulfur dioxide and form sulfuric acid. The sulfuric acid is then removed before release is into the atmosphere making sure that the air is free of sulfur dioxide pollution.
