Method for automatically controlling nitrogen oxide concentration of denitrification system

Abstract

The invention discloses a method for automatically controlling the nitrogen oxide concentration of a denitrification system. The method comprises the steps that S1, opening of an adjusting valve is adjusted, and after the concentration of nitrogen oxides in flue gas discharged out from a boiler keeps stable, the step S2 is executed; and S2, an automatic controls device is controlled to enter intothe automatic control mode, specifically, under the automatic control mode, the automatic control device controls the concentration of the nitrogen oxides in the flue gas discharged out from the boiler every the time interval delta T according to the following steps from S2.1 to S2.4. The concentration of the nitrogen oxides in the flue gas discharged out from the denitrification system is automatically controlled, it can be guaranteed that the concentration of the nitrogen oxides is stabilized to be near a nitrogen oxide target value SAT preset by an operator, it is guaranteed that ammoniacalnitrogen does not exceed the standard, and meanwhile the input quantity of a urea solution in the automatic control process is saved. A test shows that compared with a conventional method, fluctuation of the concentration of the nitrogen oxides at an outlet of the denitrification system adopting the method is stabilized from being larger than + / -100 mg / Nm<3> to being smaller than + / -15 mg / Nm<3>,and meanwhile the dosage of urea is saved by 50%.

Description

technical field [0001] The invention relates to an automatic control method of nitrogen oxide concentration in a denitrification system. Background technique [0002] At present, the denitrification system uses the FOXBORO IA DCS system for distributed control. Its automatic control schemes include constant flow dosing and boiler load calculation methods, which are manually switched under different working conditions. However, it has been found through actual use that these two methods are both The stable control of nitrogen oxides cannot be achieved, and more urea can only be added, but this will cause ammonia nitrogen to exceed the standard, and at the same time, the waste of urea is also great. Contents of the invention [0003] The technical problem to be solved by the present invention is to provide an automatic control method for nitrogen oxide concentration in a denitrification system. [0004] To solve the problems of the technologies described above, the technica...

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Problems solved by technology

[0002] At present, the denitrification system uses the FOXBORO IA DCS system for distributed control. Its automatic control schemes include constant flow dosing and boiler load calculation methods, which are manually switched under different working conditions. However, it has been found through actual use that these two methods are both The stable control of nitrogen oxides cannot be achieved, and more urea can only be added, but it will cause ammonia nitrogen to exceed the standard, and the waste of urea is also great

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