Method for calculating safe value of CO concentration at outlet of coal mill

Abstract

The invention relates to a method for calculating the safe value of CO concentration at an outlet of a coal mill, belonging to the technical field of safe operation of boiler auxiliaries. The method comprises the steps of carrying out a CO precipitation characteristic experiment of coal property to obtain a fitting function U (T) of CO precipitation rate u of the coal property and temperature T; calculating based on a principle of conservation of energy to obtain final temperature T0 after wind and powder mixing balance; calculating flow velocity to obtain retention time t0 of pulverized coal particles in the coal mill; combining the fitting function U (T), the final temperature T0 and the retention time t0 to obtain the needed CO concentration value u at the outlet of the coal mill. After the method is adopted, the technology gap of calculating the safe value of the CO concentration at the outlet of the coal mill is filled up, and theoretical support is provided for the safe operation of the coal mill and a coal pulverizing system.

Description

technical field [0001] The invention relates to the technical field of coal pulverizers, in particular to a calculation method for CO concentration at the outlet of a medium-speed coal pulverizer. The utility model belongs to the technical field of safe operation of boiler auxiliary equipment. Background technique [0002] Most modern boilers use a direct-blowing pulverizing system. Equipped with a medium-speed coal mill, as the most important equipment in the pulverizing system, it provides a place for grinding and drying coal. In the coal mill, the raw coal is ground into finer coal powder, mixed with high-temperature primary air and dried, and then the air-powder mixture passes through the separator located on the upper part of the coal mill, and the coarser coal powder particles are separated. Falling back to the coal mill for re-grinding, the lower coal particles flow out of the coal mill with the primary air and are sent to the combustion chamber for combustion. The...

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Problems solved by technology

②The temperature rise in a local small area is not easy to be captured by the temperature measuring point of the coal mill, that is to say, the temperature measuring point of the coal mill can only reflect the average temperature and its changing trend in the coal mill, It cannot sensitively reflect the temperature change in the local area even if it is a large temperature change.

③Because the method of limiting the outlet temperature of the coal mill is not ideal, a very conservative temperature limit is generally adopted, resulting in the primary air at the inlet of the coal mill needing to be mixed with a large amount of cold air, thereby reducing the efficiency of the air preheater

At present, power plants generally set the safe value of CO concentration as 150ppm or 200ppm, but this value has no theoretical basis, and does not take into account the impact of changes in the working conditions of the pulverizing system on the safe value

At present, there is no calculation method for the theoretical safety value of CO concentration at the outlet of the coal mill

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