Accurate measurement method for escaping ammonia after SCR device in thermal power plant

Abstract

The aim of the invention is to provide an accurate measurement method for escaping ammonia after an SCR device in a thermal power plant, which is used for solving the technical problem of accurate measurement for escaping ammonia. The accurate measurement method for escaping ammonia after an SCR device in a thermal power plant includes the steps: selecting a rectangular flue cross section as a measurement plane between an SCR device outlet and an air preheater inlet, and equally dividing the flue cross section into m*n measuring points; measuring ammonia gas concentration of each point; and correcting flue gas velocity vij, and then performing arithmetic average calculation on the actual value of NH3tp at each sampling time in a sampling period, to obtain the actual escaped ammonia value NH3AV in the measurement period. The invention has the advantages of simple measurement method and more accurate measurement result.

Description

technical field [0001] The invention relates to the technical field of measuring methods for ammonia escape in thermal power plants, in particular to a method for accurately measuring ammonia escape after an SCR device in a thermal power plant. Background technique [0002] As the country pays more and more attention to the emission of power plants, in order to control the emission of NOx in the flue gas, more and more thermal power plants have carried out the transformation of denitrification devices, most of which adopt SCR technology. SCR is a selective catalytic reduction technology. It is generally located in the flue before the air preheater after the SCR device. The reaction principle is that ammonia or urea solution is sprayed into the SCR device through the nozzle and reacts with NOx in the flue gas to form N2. Due to the existence of objective factors such as uneven flow field distribution and uneven NOx distribution in the flue gas, excessive NH3 must be injected ...

AI Technical Summary

Problems solved by technology

There are the following disadvantages in measuring the content of ammonia in the prior art: (1) sampling the flue gas directly, because ammonia is easily mixed with SO in the flue gas when it is lower than 250 ° C 2 , SO 3 Combined to form ammonium salts that stick to the pipe wall of the sampling system, causing large errors in sampling results; (2) The flue downstream of the SCR has a large cross-sectional area, the internal flue gas flow field is complex, and the velocity distribution is uneven. In order to obtain accurate escape ammonia values , it is necessary to carry out speed weighted correction on the measured escape ammonia value of each measuring point, instead of just taking the arithmetic mean value

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