Method for deep sliding pressure shutdown of circulating fluidized bed boiler unit

Abstract

The invention discloses a method for deep sliding pressure shutdown of a circulating fluidized bed boiler unit. Oil guns are fed in for stable combustion before coal feeders are shut down till all thecoal feeders are shut down, the steam temperature, the steam pressure and the boiler bed temperature continue to be reduced according to a sliding shutdown curve through the heat storage capacity ofa boiler and adjustment of the force and the primary air volume of the oil guns, and the overall temperature and pressure of the boiler are reduced to a low level in a sliding manner. Boiler waste heat is sufficiently utilized for generating much power, heat losses in the furnace shutdown process are reduced, the maintenance waiting time is shortened, and uniform cooling of the boiler unit is achieved.

Description

technical field [0001] The invention relates to the technical field of circulating fluidized bed boiler power generation, in particular to a method for shutting down a circulating fluidized bed boiler unit with deep sliding parameters. Background technique [0002] The circulating fluidized bed boiler adopts the most industrialized low-quality coal combustion technology containing coal gangue. Its main feature is that the boiler furnace contains a large amount of materials. During the combustion process, a large amount of materials are carried to the upper part of the furnace by the flue gas. Through the separator arranged at the outlet of the furnace, the larger particle material is separated from the flue gas, and the material is returned to the combustion chamber of the furnace through the return device at the lower part of the separator to participate in the secondary combustion and further burn up the residual carbon. Since the material is combusted multiple times in th...

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Problems solved by technology

[0008] Using the above outage method, after the boiler is shut down, the overall temperature and pressure of the boiler are still in a relatively high state, and the boiler has a large amount of waste heat that is not used, resulting in a waste of energy. If it is cooled by forced ventilation at this time , pressure reduction, temperature and steam pressure drop too fast, furnace, flue, steam drum, pipe, header, and heating surfaces are not cooled uniformly, and the boiler unit cannot withstand short temperature due to the difference in expansion coefficient between pouring material and steel. Therefore, the boiler unit can only reduce the temperature and pressure by natural cooling at this time, but because the boiler unit needs natural cooling and lowering the temperature, the range of pressure reduction is relatively large, and the natural cooling and depressurization of the boiler unit The time is longer, and the "waiting" time for boiler unit outage maintenance is also longer, generally about 168 hours

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