Ammonia spraying control system

Abstract

The invention relates to the denitration field of coal-fired boilers in a heat-engine plant, in particular to an ammonia spraying control system of a boiler denitration system. The control system is mainly used for improving control precision of NOX concentration at a denitration exit. The control system comprises a multimode prediction module, a control part and an execution mechanism. The multimode prediction module is used for predicting the NOX concentration at the denitration exit. The control part is used for calculating to-be-compensated ammonia spraying quantity according to the predicted NOX concentration at the denitration exit. The execution mechanism is used for allowing a denitration system to acquire the to-be-compensated ammonia spraying quantity according to the instruction of the control part. According to the invention, through feedforward, override and feedback of the ammonia spraying quantity, the discharged pollution processing level of the boiler denitration system is reduced; by establishing the multimode prediction module of the NOX concentration at the denitration exit, prediction precision of the NOX concentration at the denitration exit can be ensured when a combustion system of the boiler is in different load states; and by adopting an ammonia spraying control mechanism combining the feedforward, the override and the feedback, precise control of the ammonia spraying quantity is achieved.

Description

technical field [0001] The invention relates to the field of denitrification of coal-fired boilers in thermal power plants, in particular to an ammonia injection control system. Background technique [0002] Since the combustion efficiency and NOx of the thermal power plant boiler system are a pair of contradictions, the output of the boiler needs to reach a certain efficiency, resulting in NO X Emissions are not always at satisfactory levels. Therefore, the boiler needs to be equipped with a flue gas denitrification system to further reduce NO X emissions. The current denitrification methods mainly include selective catalytic reduction (SCR), non-selective catalytic reduction (SNCR), and SNCR / SCR combined flue gas denitrification technology developed on the basis of the two. Taking the SCR denitrification device as an example, it mainly includes the SCR denitrification system and the ammonia storage and preparation system. Among them, the ammonia storage and preparation...

AI Technical Summary

Problems solved by technology

It can be seen that the global SVM prediction model cannot achieve satisfactory prediction accuracy for the global working conditions

Analyzing the reason, due to the consideration of the NO X The changes of concentration and input parameters are relatively complex, such as with multi-stage and multi-modal characteristics, the global prediction model may only accurately describe the correspondence between one or several modes, resulting in boilers in other modes The error is large in the mode (that is, the expected prediction accuracy cannot be achieved for each mode)

Or, although the global prediction model covers the change characteristics of all stages, it cannot accurately predict each mode (that is, the expected prediction accuracy cannot be achieved for each mode)

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