Ammonia spraying optimization control method and system for SCR flue gas denitrification device

Abstract

The invention discloses an ammonia spraying optimization control method and system for an SCR flue gas denitrification device. The control method comprises the following steps: dividing an inlet flueand an outlet flue into grids; matching the grids with the inlet flue and the outlet flue one-by-one; sampling each inlet flue grid and each outlet flue grid respectively; by sampling each corresponding inlet flue grid and outlet flue grid, analyzing and calculating a DCS (Distributed Control System) and carrying out partitioned ammonia spraying control on the total ammonia spraying amount and each corresponding inlet flue grid area according to a calculation result. Partitioned differential control of ammonia spraying is realized, over-spraying and under-spraying of ammonia are reduced, the ammonia escape rate is reduced, energy is saved, consumption is reduced, and the safety of a unit is improved.

Description

technical field [0001] The invention relates to the technical field of flue gas denitrification, in particular to an ammonia injection optimization control system and method for an SCR flue gas denitrification device. Background technique [0002] The people's requirements for a beautiful environment are gradually increasing. In order to meet the people's needs for a better life, the state has also introduced a series of policies and measures to encourage thermal power plants to implement ultra-low emission transformation. In the denitrification transformation, some positive measures have also been taken. The first is to further optimize the design and transformation of the flow field to ensure the flue gas flow rate and NO x Uniformity of concentration distribution. However, due to the limited space of the site, the effect is not high. So take to increase the SCR system inlet NO x The number of concentration measurement probes has been changed from one sampling probe to...

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Problems solved by technology

However, due to the limited space of the venue, the effect is not high

So take to increase the SCR system entrance NO x The number of concentration measurement probes has been changed from one sampling probe to three sampling probes, and multi-point flue gas mixed sampling, but these methods still make the SCR system inlet NO x Concentration measurement data is still not representative, and the actual concentration of the entire flue cross-section cannot be measured

At the same time, the ammonia injection control system still uses a regulating valve for adjustment, which cannot meet the needs of different ammonia injection volumes in various areas of the flue cross section, resulting in uneven ammonia / nitrogen molar ratio. If it is too large, ammonia cannot fully participate in the reaction, and ammonia escapes from the reactor outlet. Increase; if it is too small, the amount of ammonia injection will be insufficient, NO x Not all of the reaction can be reduced and absorbed, causing the emission concentration to exceed the standard

The inhomogeneity of the velocity field also has some influence on the ammonia / nitrogen molar ratio, which cannot be corrected by the control logic

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