Search

CN-121971992-A - SCR denitration reactor ammonia injection control method and system

CN121971992ACN 121971992 ACN121971992 ACN 121971992ACN-121971992-A

Abstract

The invention discloses an ammonia spraying control method and system for an SCR denitration reactor, which comprises the steps of dividing a flue into a plurality of space regions, arranging an ammonia spraying unit in each space region, acquiring the concentration of nitrogen oxides in each space region, predicting the concentration change of inlet nitrogen oxides based on feed-forward information of unit operation parameters, adjusting the ammonia flow of the ammonia spraying unit, and finely adjusting the flow of the ammonia spraying unit in each space region according to the concentration of nitrogen oxides in each space region so that the concentration of nitrogen oxides in each space region tends to a target value.

Inventors

  • Long Xingyou
  • WANG SHAN
  • XIN QIANG
  • SUN GANG
  • MA CHAO
  • LONG WEIRONG
  • TIAN CHENGJUN
  • DING YUAN
  • LIU QIWEI
  • HE CANHUI
  • ZHAO WENQI
  • SHAO HONGJIE
  • WANG ZHE

Assignees

  • 贵州大方发电有限公司
  • 同方环境股份有限公司

Dates

Publication Date
20260505
Application Date
20251224

Claims (10)

  1. 1. The ammonia spraying control method of the SCR denitration reactor is characterized by comprising the following steps of, Dividing the flue (3) into a plurality of space areas (31), and arranging an ammonia spraying unit (1) in each space area (31); Acquiring the concentration of nitrogen oxides in each spatial region (31); Based on feedforward information of unit operation parameters, predicting concentration change of nitrogen oxides at an inlet, and adjusting ammonia flow of an ammonia spraying unit (1); According to the concentration of the nitrogen oxide in each space region (31), the flow rate of the ammonia injection unit (1) in each space region (31) is finely adjusted so that the nitrogen oxide concentration in each space region (31) tends to a target value.
  2. 2. The method for controlling ammonia injection in an SCR denitration reactor according to claim 1, wherein the step of obtaining the concentration of nitrogen oxides in each spatial region (31) comprises: monitoring the concentration of the nitrogen oxides in the flue gas in each space region (31) through a CEMS module; The monitored nitrogen oxide concentration is sent to a control unit.
  3. 3. The ammonia injection control method of the SCR denitration reactor according to claim 2, wherein the steps of predicting the concentration change of the inlet nitrogen oxide based on the feedforward information of the unit operation parameters, and adjusting the ammonia flow rate of the ammonia injection unit (1) include: Collecting unit load, coal types, coal quantity, air quantity, oxygen concentration and coal mill operation parameters; forming a differential curve or a differential table by analyzing the parameters; and inputting the differential result into a control unit to control the flow of the ammonia in the ammonia spraying unit (1).
  4. 4. The method for controlling ammonia injection in an SCR denitration reactor according to claim 3, wherein fine-tuning the flow rate of the ammonia injection unit (1) in each space region (31) comprises: The control unit receives the concentration of nitrogen oxides in each space region (31) and controls the flow rate of the ammonia spraying unit (1) in each region.
  5. 5. An ammonia spraying system of an SCR denitration reactor, which is characterized by comprising the following components: the ammonia spraying unit (1) is used for inputting ammonia into the flue (3); the flow control unit (2), the said flow control unit (2) is used for controlling the flow of ammonia in the said ammonia spraying unit (1); the flue gas monitoring unit is used for acquiring the concentration of nitrogen oxides at the outlet of the SCR reactor and each space region (31); And the control unit is connected with the ammonia spraying unit (1), the flow control unit (2) and the smoke monitoring unit and is used for controlling the operation of each unit.
  6. 6. The ammonia spraying system of the SCR denitration reactor according to claim 5, wherein the ammonia spraying unit (1) comprises a dilution fan (13), a flue gas heater (14) and an ammonia air mixer (15) which are sequentially arranged on a first pipeline (12), the ammonia air mixer (15) is connected with a second pipeline (11), the second pipeline (11) is used for conveying ammonia, and an ammonia spraying branch pipe (16) which is matched with a space region (31) is arranged at the rear end of the second pipeline (11).
  7. 7. The ammonia spraying system of the SCR denitration reactor according to claim 6, wherein a plurality of branches (17) are arranged at the tail end of the ammonia spraying branch pipe (16), and the branches (17) are uniformly arranged along the section direction of the flue (3).
  8. 8. The ammonia spraying system of the SCR denitration reactor according to claim 7, wherein the flow control unit (2) comprises a first regulating valve (21) and a first flowmeter (22) which are arranged at the front end of the ammonia air mixer (15) of the second pipeline (11), and a second regulating valve (23) and a second flowmeter (24) which are arranged on the ammonia spraying branch pipe (16) of the second pipeline (11), and the branch pipe (17) is provided with a switch valve (25).
  9. 9. The ammonia spraying system of the SCR denitration reactor of claim 8, wherein the flue gas monitoring unit comprises a CEMS module arranged at an outlet of the SCR reactor and used for inspecting the concentration of nitrogen oxides and the concentration of ammonia in flue gas in each space region (31).
  10. 10. The ammonia spraying system of the SCR denitration reactor according to claim 9, wherein the control unit comprises a controller for receiving the concentration of nitrogen oxides and the concentration of ammonia output by the flue gas monitoring unit and controlling the ammonia spraying amount of the ammonia spraying unit (1) through the flow control unit (2).

Description

SCR denitration reactor ammonia injection control method and system Technical Field The invention relates to the technical field of denitration ammonia injection, in particular to an ammonia injection control method and an ammonia injection control system for an SCR denitration reactor. Background The coal-fired power plant is provided with a denitration system according to the environmental protection requirement, so that the emission of flue gas reaching the standard is ensured, the reducing agent of the denitration system usually uses liquid ammonia and urea, and the preparation of ammonia mainly comprises the methods of preparing ammonia from liquid ammonia, preparing ammonia from urea through pyrolysis, preparing ammonia from urea through hydrolysis and the like. Ammonia gas is sprayed into the SCR reactor through an ammonia spraying system, and nitrogen oxides in the flue gas are removed through the action of a catalyst. At present, a conventional manual control mode is generally adopted in a denitration ammonia injection system, a fine partition adjustment means is lacked, the concentration of nitrogen oxides in flue gas continuously changes along with the load and combustion conditions of a boiler, so that the severe fluctuation of nitrogen oxides at an outlet of an SCR (selective catalytic reduction) reactor and the spatial non-uniformity of the nitrogen oxides are caused, if the ammonia injection amount cannot be accurately controlled, the ammonia escape exceeds standard, the resistance of a catalyst is increased, the ammonia consumption and the overhaul cost of an air preheater are increased, the service life of the catalyst is shortened, and the real-time standard emission of the nitrogen oxides cannot be ensured. Disclosure of Invention Therefore, the invention aims to solve the technical problems of controlling the ammonia spraying amount in a partitioning way and exceeding the standard of nitrogen oxides and exceeding the standard of ammonia escape in the flue gas emission. The technical problem is solved by the following technical scheme that the invention provides an ammonia spraying control method for an SCR denitration reactor, which comprises the following steps: dividing the flue into a plurality of space areas, and arranging an ammonia spraying unit in each space area; Acquiring the concentration of nitrogen oxides in each space region; based on feedforward information of unit operation parameters, predicting concentration change of nitrogen oxides at an inlet, and adjusting ammonia flow of an ammonia spraying unit; and (3) according to the concentration of the nitrogen oxide in each space region, finely adjusting the flow of the ammonia spraying unit in each space region so that the concentration of the nitrogen oxide in each space region tends to a target value. In a preferred embodiment of the ammonia injection control method of the SCR denitration reactor of the present invention, the obtaining the concentration of the nitrogen oxide in each spatial region includes: Monitoring the concentration of the nitrogen oxides in the flue gas in each space area through a CEMS module; The monitored nitrogen oxide concentration is sent to a control unit. In an preferable embodiment of the ammonia injection control method of the SCR denitration reactor of the present invention, the predicting the concentration change of the inlet nitrogen oxide based on the feedforward information of the unit operation parameter, and adjusting the ammonia flow of the ammonia injection unit includes: Collecting unit load, coal types, coal quantity, air quantity, oxygen concentration and coal mill operation parameters; forming a differential curve or a differential table by analyzing the parameters; and inputting the differential result into a control unit to control the flow of the ammonia gas in the ammonia spraying unit. In a preferred embodiment of the ammonia injection control method of the SCR denitration reactor of the present invention, the fine adjustment of the flow rate of the ammonia injection unit in each space region includes: The control unit receives the concentration of the nitrogen oxides in each space area and controls the flow of the ammonia spraying unit in each area. The invention further provides an ammonia spraying system of the SCR denitration reactor, which comprises an ammonia spraying unit, wherein the ammonia spraying unit is used for inputting ammonia into a flue; The flow control unit is used for controlling the flow of the ammonia in the ammonia spraying unit; the flue gas monitoring unit is used for acquiring the concentration of nitrogen oxides in each space region and the outlet of the SCR reactor; And the control unit is connected with the ammonia spraying unit, the flow control unit and the smoke monitoring unit and is used for controlling the operation of each unit. In a preferred embodiment of the ammonia spraying system of the SCR denitration reactor, the ammonia spraying u