Circulating fluidized bed boiler
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Dear expert, how is desulfurization designed for circulating fluidized bed boilers? How should calcium and sulfur be considered?
For desulfurization in circulating fluidized bed boilers, it is best to add limestone inside the furnace for this purpose. The advantage of this approach is that the limestone circulates along with the return material, allowing it to be reused multiple times; as a result, its concentration increases, meaning there is a higher ratio of calcium to sulfur. This in turn helps to reduce the amount of limestone required. Due to the high calcium-sulfur ratio, the desulfurization effect is better, which is beneficial for reducing the costs associated with desulfurization
The theory is very simple, but in practical applications it is recommended to burn limestone with a concentration of 5-8% and a size of 1-3 mm mixed together with coal. Different coal types have varying sulfur contents, which need to be determined through testing! Blending can be automatically accomplished through coal sorting, crushing, and grading systems!
For coals with a relatively high sulfur content, a flue gas desulfurization unit may sometimes need to be added after the CFB system
Our factory has adopted the installation of desulfurization equipment
The calcium-sulfur ratio is determined by the sulfur content in the coal as well as the activity of the limestone itself. Generally, a value of 1.8 to 2.4 is chosen based on experience, mainly to facilitate design calculations. In actual operation, power plants usually control the amount of limestone used according to their actual SO2 emissions
In addition to control measures for limestone dosage based on SO2 emissions, there are now many external desulfurization devices that also prove to be effective.