System and method for preparing ammonia gas by using ammonia water for cement plant SCR denitration

Abstract

The invention relates to a system and method for preparing ammonia gas by using ammonia water for cement plant SCR denitration and belongs to the technical field of environmental protection. In the system for preparing ammonia gas by using ammonia water for cement plant SCR denitration, an ammonia water delivery pump and a compressed air inlet valve are communicated with a double-fluid atomization spray gun through pipes, the double-fluid atomization spray gun is installed on an evaporator for atomization, the lower portion of the evaporator is communicated with an intermediate tank through a pipe, the upper portion of the evaporator is communicated with an ammonia gas absorption tank through an evaporator safety valve, and the evaporator is communicated with an ammonia gas outlet valve. The method for preparing ammonia gas by using ammonia water for cement plant SCR denitration comprises the steps that the ammonia water is fed into the ammonia water-compressed air double-fluid atomization spray gun through the ammonia water delivery pump for atomization, atomized micron-grade-particle-size liquid drops enter the evaporator, latent heat of saturated vapor is utilized to evaporate the ammonia water, ammonia-water vapor mixed gas is led to a cement plant SCR denitration system. The system has the advantages of being simple in structure, reliable in performance, accurate in control, flexible, convenient, safe, reliable, stable in process, low in operation cost, high in evaporation efficiency and the like.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and in particular relates to a system for preparing ammonia gas from ammonia water for SCR denitrification in a cement plant and a method thereof. Background technique [0002] At present, the "Emission Standard of Air Pollutants for the Cement Industry" GB4915-2013 stipulates that the emission value of nitrogen oxides in general areas should be controlled at 400mg / m 3 Below, the emission value of nitrogen oxides in key areas shall be controlled at 320mg / m 3 Below, the emission value of nitrogen oxides in some cities is lower than 200mg / m 3 , so under this emission requirement, it is necessary to adopt selective catalytic reduction SCR denitrification technology with higher denitrification efficiency. So far, all cement plants are basically equipped with selective non-catalytic SNCR denitrification systems, and also have ammonia water, etc. Reductant, if the SCR denitrification...

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Problems solved by technology

[0003] The technologies for producing ammonia gas from ammonia water mainly include: the first is the ammonia distillation tower, because the structure of the ammonia distillation tower is very complex and the tower body is huge, and the amount of SCR denitrification reducing agent in the cement plant is small, and the cost is expensive

The second is to use hot flue gas to directly heat ammonia water. The dust concentration in hot flue gas is very high. Using hot flue gas to directly heat ammonia water will cause problems such as ammonia water spray gun and valve blockage, short service life, low operating rate, and frequent use. Clean up and maintain

The third is to use hot flue gas to indirectly heat ammonia water. Hot flue gas indirectly heats ammonia water. First, the evaporation of ammonia water requires a lot of heat, so heating ammonia water requires a large amount of hot flue gas, resulting in a large heat exchanger and dust. Abrasion of the heat exchanger, low service life, high cost and other technical problems

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