Uniform ammonia spraying system and method for controlling same

Abstract

The invention discloses a uniform ammonia spraying system and a method for controlling the same. The uniform ammonia spraying system comprises a flue. The flue is connected with a furnace outlet of a boiler, a first flue gas sampling opening is formed in a location, which is positioned between the furnace outlet and a coal economizer section, of the flue and is used for measuring the initial content of NOX at the furnace outlet, a plurality of flue gas flow velocity sensors are distributed at different locations of a vertical section of the flue and are positioned between the coal economizer section and a denitration catalyst section, a plurality of ammonia gas spray nozzles are distributed on the same vertical section and are connected with a multi-channel ammonia gas delivery control circuit, and a second flue gas sampling opening is formed in a location, and which is positioned between the denitration catalyst section and an air preheating section, of the flue and is used for detecting treated flue gas to determine whether the content of NOX in the treated flue gas is lower than a standard value or not. The uniform ammonia spraying system and the method have the advantages that the blindness of local ammonia spraying in the flue can be reduced, ammonia escape can be decreased, air preheater blocking phenomena can be reduced, accordingly, long-term stable and safe running of units can be guaranteed, and the uniform ammonia spraying system and the method are beneficial to actual running of power plants on the aspects of safety and economical efficiency.

Description

technical field [0001] The invention relates to a uniform ammonia spraying device and a control method thereof, which is an ammonia spray uniformity control system and a control method thereof based on a flow measuring device. Background technique [0002] In the existing denitrification technology, only the overall NO at the outlet of the denitrification is considered X The (nitrogen oxide) value is lower than the environmental protection requirements. The Chinese patent with the publication number CN104238519A discloses "a system and method for SCR out-of-stock control in coal-fired power stations". The technical solution is to solve the problem of NO X For the emission problem, a pressure measuring device is installed in the flue to measure the flow rate, and an ammonia injection grill is installed to release ammonia gas. However, since the ammonia injection control system is a single control, although the ammonia injection grill is used, the One type of uniform ammonia ...

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Problems solved by technology

[0002] In the existing denitrification technology, only the overall NO at the outlet of the denitrification is considered X The (nitrogen oxide) value is lower than the environmental protection requirements. The Chinese patent with the publication number CN104238519A discloses "a system and method for SCR out-of-stock control in coal-fired power stations". The technical solution is to solve the problem of NO X For the emission problem, a pressure measuring device is installed in the flue to measure the flow rate, and an ammonia injection grill is installed to release ammonia gas. However, since the ammonia injection control system is a single control, although the ammonia injection grill is used, the One type of uniform ammonia injection, because the amount of flue gas and ammonia injection in different positions is different, so there will be high local ammonia injection volume and low local ammonia injection volume, and the phenomenon of ammonia escape will increase in places with high ammonia injection volume, which is easy to cause NH in tail flue 4 HSO 4 Blockage phenomenon, and local NO is easy to form in places where the amount of ammonia injection is low X The value is too large, so the technical solution has the defect that the amount of ammonia injection will be controlled suddenly due to the difference in the flue gas flow rate in the entire section.

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