Thermal power units and their nh-based 3 Measured denitrification control method and system

Abstract

The invention discloses a NH-based 3 Measured denitrification control method, including: obtaining NH at several measuring points in the flue 3 measured value; according to the NH 3 The measured value controls the amount of ammonia injection in the corresponding area of ​​the flue; the PID feedforward value is calculated according to the preset broken line function; the NOx concentration at the denitrification outlet is controlled according to the PID feedforward value. The invention also discloses a NH-based 3 Measurement of the denitrification control system and including the above NH-based 3 Measurement of the denitrification control system of the thermal power unit. The above is based on NH 3 Measured denitrification control method through multi-measuring point NH 3 Parameter monitoring can provide operators with a basis for adjusting the opening of the ammonia injection valve, making the amount of ammonia injection in each area more reasonable and effectively preventing NH 3 The problem of overspray or underspray can effectively reduce the occurrence of air preheater clogging; at the same time, by introducing the PID feedforward value into the denitration control system, the reliability of the denitration control system can be effectively improved, and the reliability of environmental protection can be improved.

Description

technical field [0001] The invention relates to the technical field of thermal power generation, in particular to an NH-based 3 Measured denitrification control methods. The present invention also relates to a kind of based on NH 3 measurement of the denitrification control system and includes the NH-based 3 Measurement of the denitrification control system of the thermal power unit. Background technique [0002] As the country's environmental protection requirements become more and more stringent, thermal power unit emission reduction is as important as safe operation. In order to control NOx emission indicators for thermal power units to achieve ultra-low emissions (ultra-low emissions: that is, to retrofit coal-fired thermal power units and increase denitrification device, desulfurization device, and dust removal device, the concentration of pollutants in the flue gas discharged into the atmosphere by the unit is up to the standard, and the NOx emission index in this c...

AI Technical Summary

Problems solved by technology

However, currently, for NH in the flue 3 The detection generally adopts single-point monitoring NH 3 , the installation method is mostly diagonal installation, the installation method is as follows figure 1 as shown, figure 1 A kind of NH disclosed in the prior art 3 Schematic diagram of the installation of the detection device; this sampling point is not of reference significance for the large cross-section flue, and cannot provide an accurate, true and effective ammonia escape value (ammonia escape: for coal-fired thermal power units, after the denitrification system is put into operation, after Excess NH after denitrification reactor 3 Concentration, NH after denitrification and ammonia injection 3 The ammonia content is the escape of ammonia (required 3 Most of the detection devices use in-situ laser measurement methods. Due to the high concentration of smoke in the flue, the laser cannot penetrate the smoke. Although the site has been installed diagonally, there is often no NH 3 data output, and the original NH 3 The measurement optical path of the instrument is short, and the sensitivity can only reach about 1ppm, which can no longer meet the needs of field process NH 3 The monitoring accuracy requirement for concentration less than 3ppm, at the same time, the original NH 3 The maintenance of the device is large, and the maintenance is very troublesome, and it is often necessary to align the light (on-site vibration and unit load changes may cause the optical path of the instrument to deviate); in addition, the original single-point measurement of NH 3 , cannot reflect the NH in the whole flue 3 content, and cannot provide operators with NH in the flue gas 3 The distribution of the flow field, and the amount of ammonia injection in the flow field cannot be adjusted through the ammonia injection leveling valve, resulting in NH in some areas of the flue 3 Overspray, some areas NH 3 Under-spray, causing NOx can not be precisely controlled, resulting in transient over-standard emissions

[0004] Therefore, how to avoid due to the inability to accurately measure the NH 3 As a result, the emission of NOx cannot be accurately controlled, which is a technical problem that those skilled in the art need to solve

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