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

Abstract

The invention provides a method for preheating and pre-combusting pulverized coal in the tertiary air duct of a cement precalcining kiln. A decomposition furnace is set between the rotary kiln and the suspension preheater as the second heat source of the system. A certain proportion of pulverized coal is sprayed into the wall of the tertiary air duct at a certain distance, so that the pulverized coal and the tertiary hot air enter the calciner together. Generally, pulverized coal is sprayed 5-10m away from the tertiary air inlet of the calciner. The pulverized coal sprayed into the tertiary air duct from the wall of the tertiary air duct is divided into two to four symmetrical injections. The ratio of the pulverized coal entering the tertiary air pipe to the pulverized coal directly entering the calciner is 2:8-3:7. The gas-solid ratio of pulverized coal entering the tertiary air duct is subject to the tertiary air temperature of the calciner reaching 950°C-1000°C. Generally, the first branch pipe is led from the pulverized coal air pipe to the calciner to the third air pipe.

Description

technical field [0001] The invention relates to a method for preheating and pre-burning pulverized coal in the tertiary air duct of a cement precalcining kiln, which belongs to the technical field of new dry method cement clinker firing, and is mainly used to solve the problem that the pulverized coal combustion speed in the current 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 calcina...

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

Images