Tertiary air duct coal powder preheating and prefiring technique for cement predecomposition kiln

Abstract

The present invention provides a tertiary air pipe coal powder preheating and preburning technique for cement predecomposition kiln. Between rotary kiln and suspension preheater is st a decomposition furnace as second heat source of said system, the coal powder can be sprayed into the tertiary air pipe according to a certain propoertion from tertiary air pipe wall at a certain distance from tertiary air inlet of decomposition furnace to make the coal powder and tertiary air be together fed into the decomposition furnace. Generally, the coal powder can be sprayed into the tertiary air pipe at a distance 5-10 m from tertiary air inlet of decomposition furnace. The ratio range of the coal powder fed into the tertiary air pipe and the coal powder directly fed into decomposition furnace is 2:8-3:7, and the air-solid ratio of coal powder fed into tertiary air pipe takes that tertiary air temp. of decomposition furnace is reached to 950 deg.C-1000 deg.C as criterion.

Description

technical field [0001] The invention relates to a coal powder preheating and pre-burning technology for the tertiary air duct of a cement precalcining kiln, which belongs to the technical field of new dry process cement clinker firing, and is mainly used to solve the problem that the burning speed of coal powder in the existing calciner is relatively slow and prone to The problem of crust clogging and high requirements on coal quality. Background technique [0002] The precalciner is currently the most advanced process equipment for cement clinker production. A precalciner is added between the rotary kiln and the suspension preheater as the second heat source of the system, so that all the fuel is added from the kiln head in the past. Part of the fuel is added from the kiln head, and part of the fuel is added from the calciner, which improves the heat distribution in the kiln system and moves the most heat-consuming carbonate decomposition process in the clinker calcination ...

AI Technical Summary

Problems solved by technology

If the combustion speed is too slow, the pulverized coal will not burn completely in the furnace, which will easily cause the temperature distribution of the preheater system to be unreasonable, and cause skin blockage of the pipeline and preheater

Therefore, general coal decomposition furnaces have great limitations on fuel quality, especially for low-volatile coal.

In response to this problem, various countries in the world have successively carried out various researches. The main ideas for solving the problem are: appropriately expand the furnace capacity, prolong the residence time of the airflow in the furnace, and improve the structure of the furnace body so that the three-dimensional flow field in the furnace cavity is conducive to improving the gas flow rate. , solid residence time ratio, improve the form, structure and layout of the burner, so that the fuel can be ignited as soon as possible after entering the furnace, and select the furnace type, process flow, layout, etc. according to the needs. Although the above measures can improve to a certain extent, but Due to the failure to consider the problem from the direction of preheating and pre-combustion, it is not direct to increase the combustion speed of pulverized coal, so it only partially solves the problem, but does not fundamentally solve the problem

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