Ammonia-escaping-rate online obtaining method for desulfurization and denitrification control

Abstract

The invention discloses an ammonia-escaping-rate online obtaining method for desulfurization and denitrification control. According to the technical scheme, the ammonia-escaping-rate online obtaining method includes the steps that when an SCR denitrification system of a coal firing unit is in the running state, oxygen content conversion is carried out on NOx concentration data, given by a smoke composition analyzer, of an inlet and an outlet of an SCR reactor of the denitrification system, the NO content and the NO2 content of the smoke of the inlet and the outlet of the reactor under the practical oxygen content are obtained, and then the ammonia escaping rate is calculated according to the conversion result and data of the ammonia spraying amount and the smoke flow of the inlet of the SCR reactor. According to the ammonia-escaping-rate online obtaining method, the ammonia escaping rate of the SCR denitrification system is online calculated according to the practical denitrification effect; in the flow processing process, nitric oxide is subdivided into NO and NO2 for analysis and calculation, and the accuracy of the calculation result is greatly improved; the ammonia spraying amount and the smoke flow of the inlet of the SCR reactor are collected in real time, and therefore the real-time performance of calculation of the ammonia escaping rate is guaranteed.

Description

technical field [0001] The invention relates to an online acquisition method of ammonia escape rate at the outlet of an SCR reactor in a denitrification system of a large-scale coal-fired unit, and belongs to the technical field of boilers. Background technique [0002] Selective Catalytic Reduction (SCR) is the main denitrification process widely used in large coal-fired units at home and abroad. SCR denitrification process uses ammonia (NH 3 ) as the reducing agent, ammonia gas is sprayed into the flue through the ammonia injection grid, fully mixed with the flue gas, enters the SCR reactor, and under the action of multi-layer catalysts, the NO in the flue gas X reduced to N 2 and H 2 O, complete NO X removal. [0003] During the denitrification process, part of the unreacted ammonia enters the downstream equipment together with the flue gas, forming ammonia escape. The harm of ammonia escape is mainly reflected in the following aspects: [0004] a. Ammonia escape wi...

AI Technical Summary

Problems solved by technology

The disadvantage of this measurement method is that an on-site gas pretreatment system is required, the maintenance workload of the gas circuit system is large, and the length of the sampling pipeline is limited by the measuring instrument and site conditions, generally less than 2 meters, and the pipeline is too long. Sampling accuracy has a certain impact

[0013] However, the chemiluminescence analysis method has problems with the conversion efficiency of the converter. The sample gas extracted is in a high-temperature, high-dust, high-humidity and high-corrosion environment. The sampling probe is easy to block and the system is easy to corrode, which reduces the conversion efficiency of the converter.

In addition, in the process of sample gas extraction and transmission, there are factors such as water absorption and trace ammonia, which cause a certain amount of ammonia loss and reduce the measurement accuracy of ammonia escape rate.

[0014] In summary, there are large deviations in the measurement results of traditional ammonia slip rate measurement methods, so it is of great significance to find a high accuracy and real-time ammonia slip rate measurement method for desulfurization and denitrification systems

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