System and method for controlling oxynitride removal

Abstract

The invention provides a system and a method for optimally controlling ammonia denitration, which are characterized in that according to the content of oxynitride which is detected by an oxynitride sensor at the inlet of a reactor and fed into the reactor, the content of oxynitride which is detected by the oxynitride sensor at the outlet of the reactor and discharged from the reactor, and the continuous online measuring value of the oxynitride at the outlet of the reactor and the escaped ammonia amount detected by an ammonia sensor at the outlet of the reactor, the ammonia-injected amount is calculated according a transfer function; the control system has positive and negative feedback correction effects on feedforward loops, and monitors the continuous online measuring value of the oxynitride, thereby ensuring the implementation of meeting the qualified oxynitride discharge index; the control system is provided with two lag time functions so as to overcome the effect of time lag, eliminate the fluctuations of the oxynitride content and ammonia-injected amount at the outlet of the reactor; and meanwhile, the control system is also provided with an ammonia escape detection sensor for preventing the escape of ammonia.

Description

【Technical field】 [0001] The present invention relates to a control system and method for removal of nitrogen oxides, in particular to selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) or a combined method of selective non-catalytic reduction and selective catalytic reduction (SNCR-SCR) Control system and method for nitrogen oxide removal. 【Background technique】 [0002] my country is a developing country with coal as the main energy source. The country's power energy is mainly provided by coal-fired thermal power plants, and more than 1.2 billion tons of coal are directly used for combustion every year. After coal combustion, a large amount of pollutants are emitted, such as SO2 , SO3 (commonly known as SOX, sulfide); NO, NO2 (commonly known as NOX, nitrogen oxides, commonly known as "nitrate" in industry); the pollution of nitrogen oxides to the atmospheric environment, in addition to causing acid rain with other compounds, is harmful to soil and...

AI Technical Summary

Problems solved by technology

The existing control system is controlled according to the efficiency of denitrification. The amount of ammonia injection (NH3) is determined by the feedback loop of the nitrogen oxide emission NOx_out at the outlet and the nitrogen oxide content NOx_in at the SCR inlet. The forward feedback controller jointly determines that although this control logic can guarantee the denitrification efficiency of the SCR system, it only controls the denitrification efficiency, and the denitrification efficiency is not only related to the exhausted nitrogen oxides NOx_out, but also related to the nitrogen oxides imported by the SCR The content of NOx_in may be related to the NOx_out content of nitrogen oxides at the outlet, but the overall efficiency can also reach the preset efficiency. Therefore, this control logic cannot guarantee the NOx value NOx_out of the SCR outlet with qualified emissions, and it cannot guarantee the ammonia The amount of escape is within a certain range

Also, the adoption of the system time lag will have a great impact on the control effectiveness

Images