A self-denitrification system and process for calciner compartmentalized combustion self-denitration

Abstract

The invention discloses a self-denitrification system and process for calciner combustion by partition organization. A kiln gas flue is set between the kiln tail smoke chamber and the calciner. The furnace inlet of the kiln gas flue is connected to the side of the calciner. The branch pipe is connected to the bottom of the calciner cone, forming a horizontally partitioned combustion environment with a central oxygen-rich zone and a peripheral low-oxygen zone on the calciner cross section; the upper branch pipe of the tertiary air is connected to the middle of the calciner column, and the kiln gas flue is a strong reduction zone , the space inside the calciner below the upper branch pipe of the tertiary air is a weak reduction zone, and the space inside the calciner above the upper branch pipe of the tertiary air is a burnout zone, forming a longitudinal gradient combustion environment combining strong reduction zone-weak reduction zone-burnout zone. The horizontal zoned combustion environment is achieved by making the tertiary air enter vertically upward from the center of the bottom of the calciner, and the flue gas enters the wind from the side of the calciner by tangential rotation of the volute; the vertically graded combustion environment is achieved by fuel graded feeding and tertiary air distribution. The present invention realizes self-denitrification through zoned organization combustion as a whole, and improves self-denitrification efficiency.

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 calciner compartmentalized combustion self-denitration. 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 directly affects the product energy consumption of the entire pro...

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Problems solved by technology

[0013] (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%.

[0014] (2) The fuel combustion rate of the existing calciner is limited by the temperature of the combustion zone and cannot be burned quickly. It is necessary to increase the volume of the calciner and prolong the combustion time to meet the demand for combustion. On the one hand, it increases investment and space occupation, and on the other hand Increased equipment surface heat dissipation energy consumption

[0015] (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

If the combustion temperature of the calciner is too high, it is easy to burn out the refractory material of the furnace wall

[0016] (4) The calciner fuel staged combustion method can only reduce the NOx produced in the rotary kiln, but cannot reduce the NOx produced by the combustion of the fuel itself in the calciner

Moreover, it is relatively difficult to ignite and ignite the fuel in the calciner, which is likely to cause fluctuations in working conditions and affect the stability of the cement production process.

[0017] (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

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