Decomposing furnace partitioned organization combustion self-denitration system and process capable of adjusting oxygen concentration of reduction zone

Abstract

The invention discloses a decomposing furnace partitioned organization combustion self-denitration system and process capable of adjusting an oxygen concentration of a reduction zone. According to thesystem and the process, a kiln gas flue is arranged between a kiln tail flue chamber and a decomposing furnace, a furnace inlet of the kiln gas flue is connected with the side face of the decomposingfurnace, a tertiary air pipe is connected with the bottom of a decomposing furnace cone, and a transverse partitioned combustion environment with a central concentrated oxygen area and a peripheral light oxygen area is formed on the transverse section of the decomposing furnace; a strong reduction area is arranged in the kiln gas flue, a burnout area is arranged in the decomposing furnace, and longitudinal staged combustion environments with different peroxide coefficients are formed in a combined combustion space of the kiln gas flue and the decomposing furnace; and a tertiary air branch pipe is arranged between the tertiary air pipe and the kiln gas flue. The transverse partitioned combustion environment is realized by longitudinally and upwards feeding tertiary air from the center of the bottom of the decomposing furnace and tangentially feeding flue gas from the side surface of the decomposing furnace in a rotating and volute mode, and the longitudinal staged combustion environments are realized through fuel staged feeding. According to the system and the method, partitioned organization combustion self-denitration is realized on the whole, the self-denitration efficiency is improved, and the utilization of space in the strong reduction area is improved.

Description

technical field [0001] The invention relates to the technical field of flue gas denitrification in the cement industry, in particular to a self-denitration system and process for a calciner with zoned tissue combustion in a calciner that can adjust the oxygen concentration in a reduction zone. Background technique [0002] The calciner is the key equipment in the cement production process. The main component of cement raw meal is calcium carbonate, and the carbonate in cement raw meal is decomposed into oxides in the calciner, which provides a basis for the subsequent clinker sintering reaction in the rotary kiln. Since the decomposition of carbonate needs to absorb a large amount of heat, a certain amount of fuel needs to be fed into the decomposition furnace to supply it. Generally speaking, the fuel in the calciner accounts for about 60% of the fuel consumption in the entire cement clinker calcination process. The combustion status of the fuel in the decomposition direc...

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Problems solved by technology

[0011] (1) In the existing linear calciner, the kiln gas enters directly from the bottom of the calciner. Even if the fuel is graded and burned, a reduction zone is formed at the cone of the calciner, which has a certain effect on reducing NOx in the flue gas from the kiln. However, due to The flue gas from the kiln enters the furnace directly, the space of the oxygen-poor combustion zone is limited, the residence time of the denitrification reaction is short, and the denitrification efficiency is generally about 30%.

[0012] (2) The combustion speed of the existing calciner is limited by the temperature of the combustion zone and cannot be burned out quickly. It is necessary to increase the volume of the calciner and prolong the combustion time to meet the demand for burnout. On the one hand, the investment and space occupation are increased, and on the other hand, the The heat dissipation energy consumption of the equipment surface

[0013] (3) The temperature in the combustion zone of the calciner is limited by the crust on the furnace wall, which makes it difficult to further increase the temperature in the combustion zone in the existing technology

When the temperature in the combustion zone is too high, the raw material is prone to liquid phase at high temperature, resulting in skinning problems on the furnace wall

[0014] (4) The combustion temperature of the decomposition furnace is too high and it is easy to burn the refractory material of the furnace wall

[0015] (5) The method of gradient combustion in the existing calciner is limited to the interior of the calciner

Restricted by factors such as the volume of the calciner and the space of the site, the overall denitrification effect needs to be improved

Moreover, the oxygen content of the flue gas in the strong reduction zone in the existing gradient combustion system of the calciner is limited by the fuel combustion in the rotary kiln and cannot be adjusted flexibly; due to the low oxygen concentration, the fuel combustion in the strong reduction zone is limited, making this part of the space difficult Fuel combustion contributes less

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