System and method of blending combustion of coal type with low ash melting point in coal-fired utility boiler

Abstract

The invention discloses a system and method of blending combustion of a coal type with a low ash melting point in a coal-fired utility boiler and belongs to the technical field of coal-fired utility boiler operation. The coal-fired utility boiler is equipped with a positive-pressure, direct-firing, double-in and double-out steel ball coal pulverizer; the method of blending combustion of coal type with the low ash melting point in the coal-fired utility boiler comprises the following steps: the coal type with the low ash melting point and a coal type with a high ash melting point are sent into the steel ball coal pulverizer from one end of the positive-pressure, direct-firing, double-in and double-out steel ball coal pulverizer respectively; after thorough mixing and grinding, powder is uniformly output from two ends of the steel ball coal pulverizer; after the blending, compared with the melting point of the coal type with a low ash melting point, the melting point of the blended ash is increased to a relatively large extent; under various boiler loading, through adjusting the belt rotational speeds of coal feeders that correspond to the coal type with the low ash melting point and the coal type with the high ash melting point, the mixing proportion control is realized on the coal type with the low ash melting point. The system and method of blending combustion of coal type with the low ash melting point in the coal-fired utility boiler can improve the combustion and utilization proportion of the coal type with the low ash melting point to the utmost extent, on the basis of effectively relieving the boiler from coking and ensuring the safe operation of the boiler; the cost of fuel is reduced; the economical efficiency in the operation of the coal-fired utility boiler machine set is improved.

Description

【Technical field】 [0001] The invention belongs to the technical field of coal-fired power plant boiler operation, and relates to a system and method for blending and burning low-ash melting point coal in a coal-fired power plant boiler. 【Background technique】 [0002] Affected by coal supply channels or the coal market, the coal quality of many large coal-fired power plants is far from the design coal type, including some low-ash melting point coal types with lower standard coal unit prices. The use of coal with low ash melting point will bring different degrees of coking problems to the boiler. Especially with the reduction of nitrogen oxide emission standards for coal-fired power plant boilers, low-nitrogen combustion methods such as air classification and fuel classification will further promote the conversion of mineral elements in coal to compounds with low ash melting points during the combustion process, which will aggravate coking in the furnace. Severe coking of th...

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Problems solved by technology

However, the premixing in front of the furnace is also limited by the size of the coal yard and the uniformity of blending. Some power plants have too small a coal yard and do not have premixing conditions, or the uneven blending will affect the stability of operation.

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