A retrofit method for energy saving and emission reduction to reduce the emission of nitrogen oxides from ddf decomposition furnace

Abstract

The invention discloses an energy-saving and emission-reduction transformation method for reducing the emission of nitrogen oxides from a DDF cement decomposition furnace. By setting a confluence box and a gooseneck for a DDF decomposition furnace with a small volume, the residence time of the flue gas is prolonged, and part of the coal The powder is distributed to the cone of the calciner, and part of the tertiary air is sent to the middle and upper part of the calciner. The enlarged DDF calciner volume and the lower part of the pulverized coal inlet position increase the burnout rate of the pulverized coal, and the excess air in the lower part of the calciner If the coefficient is less than 1.0, under the condition of insufficient oxygen, a large proportion of CO is produced, which becomes the reducing agent for reducing and eliminating nitrogen oxides. The ash return channel is set in the confluence box to send the settled raw material and coal powder particles back to the middle nozzle of the calciner, so as to solve the problem of ash accumulation and sintering blockage, improve the processing capacity of the calciner for coarse particles, and improve the production efficiency of the kiln. The decomposition rate of raw materials is improved, and the effective energy saving and emission reduction of the cement firing system are realized through the dual effects of reducing nitrogen oxide emissions and reducing heat consumption.

Description

technical field [0001] The invention relates to the field of energy saving and emission reduction of cement kilns, in particular to a method for transforming a DDF cement decomposition furnace for energy saving and emission reduction. Background technique [0002] During the high-temperature calcination process of cement kiln, various forms of nitrogen oxides will be generated. Through targeted transformation of the decomposition furnace of cement kiln, the emission of nitrogen oxides can be effectively suppressed. The calciner mainly reduces the emission of nitrogen oxides through staged combustion of fuel or staged air supply. The staged combustion of fuel is mainly to divide the fuel into two parts (or more parts) and spray them into different positions of the calciner. Part of the fuel is sent to the cone part with low oxygen content through the auxiliary pulverized coal burner at the lower part of the calciner. area, under the conditions of higher flue gas temperature ...

AI Technical Summary

Problems solved by technology

At present, many cement kiln calciners are designed for historical reasons. The early design improperly emphasized the unit volume output of the calciner. The volume of the calciner is too small, and the residence time of pulverized coal in the furnace is insufficient, which directly affects the decomposition Insufficient combustion of pulverized coal in the furnace may easily lead to a considerable proportion of reducing gas with a large amount of potential and CO as the main symbol in the kiln flue gas discharged from the first-stage cyclone preheater, which unnecessarily increases chemical incomplete combustion heat loss

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