CN-116951455-B - Automatic control device and method for preventing secondary combustion of tail flue of boiler

CN116951455BCN 116951455 BCN116951455 BCN 116951455BCN-116951455-B

Abstract

The invention discloses an automatic control device and method for preventing secondary combustion of a boiler tail flue. The device comprises a smoke temperature detection module, a flame detection module, a steam input pipeline, a nitrogen input pipeline and a controller, wherein the smoke temperature detection module is used for detecting the temperature of smoke in a boiler tail flue, sending a temperature signal to the controller when the temperature of the smoke is higher than a preset temperature, the flame detection module is used for detecting whether flame occurs in the boiler tail flue, generating a flame signal and sending the flame signal to the controller when the flame occurs in the boiler tail flue, and the controller is used for controlling the steam input pipeline or/and the nitrogen input pipeline to spray steam or/and nitrogen into the boiler tail flue according to the temperature signal or/and the flame signal so as to prevent the smoke in the boiler tail flue from burning. The hidden trouble of secondary combustion accident of the tail flue of the boiler is eliminated in a sprouting state timely and efficiently, and the safe and stable operation of the boiler is ensured.

Inventors

ZHU JIANFENG
WU BEI
LIU LANBIN
CHEN YINGBO
MA JINXING
CHEN LONGBIN
Zheng Junrui
ZHANG TAO

Assignees

广东中南钢铁股份有限公司

Dates

Publication Date: 20260508
Application Date: 20230721

Claims (8)

1. An automatic control device for preventing secondary combustion of a boiler tail flue is characterized by comprising a smoke temperature detection module, a flame detection module, a steam input pipeline, a nitrogen input pipeline and a controller; The smoke temperature detection module is used for detecting the temperature of smoke in a tail flue of the boiler, and sending a temperature signal to the controller when the temperature of the smoke is greater than a preset temperature; the flame detection module is used for detecting whether flame appears in the boiler tail flue, and when flame appears in the boiler tail flue, a flame signal is generated and sent to the controller; The steam input pipeline is connected with the boiler tail flue and is used for spraying steam into the boiler tail flue so as to reduce the temperature of flue gas in the boiler tail flue; the nitrogen input pipeline is connected with the boiler tail flue and is used for spraying nitrogen into the boiler tail flue so as to eliminate flame in the boiler tail flue; the controller is used for controlling the steam input pipeline or/and the nitrogen input pipeline to spray steam or/and nitrogen into the boiler tail flue according to the temperature signal or/and the flame signal so as to prevent the flue gas in the boiler tail flue from burning; the zirconia module is positioned above the economizer in the tail flue of the boiler and is used for detecting the oxygen content in the flue gas and sending the oxygen content to the controller; The CO detector is positioned below the air preheater in the tail flue of the boiler and is used for detecting the content of CO in the flue gas and sending the content of CO to the controller; the coal economizer and the air preheater are both positioned in the tail flue of the boiler, the coal economizer is positioned above the air heater, the coal economizer is used for heating coal gas through the temperature of flue gas, and the air preheater is used for heating air through the temperature of flue gas; The controller is specifically used for controlling steam to be sprayed into the boiler tail flue until the temperature signal disappears when the temperature signal is generated and the flame signal is not generated, and controlling steam and nitrogen to be sprayed into the boiler tail flue until the temperature signal and the flame signal disappear when the temperature signal is not disappeared and the flame signal is generated and the oxygen content in the boiler tail flue is detected to be larger than the preset oxygen content value and the CO content is detected to be larger than the preset CO content value.
2. The automatic control device for preventing secondary combustion of a boiler afterburner according to claim 1, wherein the smoke temperature detection module comprises a first smoke temperature detection module, which is positioned above the economizer in the boiler afterburner and is used for detecting the temperature of smoke in the flue above the economizer, and when the temperature of the smoke is higher than a preset temperature, a first temperature signal is sent to the controller; The flame detection module comprises a first flame detection module which is positioned above the economizer in the tail flue of the boiler and is used for detecting whether flame appears in the flue above the economizer, and when flame appears in the flue above the economizer, a first flame signal is generated and sent to the controller; The steam input pipeline comprises a first steam input pipeline, wherein the first steam input pipeline is connected with the upper part of the economizer in the tail flue of the boiler and is used for spraying steam to the upper part of the economizer so as to reduce the temperature of flue gas in the flue above the economizer; The nitrogen input module comprises a first nitrogen input pipeline, wherein the first nitrogen input pipeline is connected with the upper part of the economizer in the tail flue of the boiler and is used for spraying nitrogen to the upper part of the economizer so as to eliminate flame in the flue above the economizer, and a first nitrogen control valve is arranged on the first nitrogen input pipeline.
3. The automatic control device for preventing secondary combustion of a boiler afterburner as set forth in claim 2, wherein the controller is further configured to control the steam input line and/or the nitrogen input line to inject steam and/or nitrogen into the boiler afterburner based on the temperature signal and/or the flame signal, comprising: If the controller only receives the first temperature signal, controlling the first steam control valve to be opened, so that the first steam input pipeline sprays steam into a flue above the economizer until the first temperature signal disappears; If the first temperature signal does not disappear, the first flame signal is received, the oxygen content is detected to be larger than an oxygen content preset value, the CO content is detected to be larger than a CO content preset value, the first nitrogen control valve is controlled to be opened, and the first nitrogen input pipeline is enabled to spray nitrogen into a flue above the economizer until the first temperature signal disappears and the first flame signal disappears.
4. The automatic control device for preventing secondary combustion of a boiler afterburner according to claim 1, wherein the smoke temperature detection module comprises a second smoke temperature detection module, which is positioned above the air preheater in the boiler afterburner and is used for detecting the temperature of smoke in the flue above the air preheater, and when the temperature of the smoke is higher than a preset temperature, a second temperature signal is sent to the controller; The flame detection module comprises a second flame detection module which is positioned above the air preheater in the tail flue of the boiler and is used for detecting whether flame appears in the flue above the air preheater, and when flame appears in the flue above the air preheater, a second flame signal is generated and sent to the controller; The steam input pipeline comprises a second steam input pipeline which is connected with the upper part of the air preheater in the tail flue of the boiler and is used for spraying steam to the upper part of the air preheater so as to reduce the temperature of flue gas in the flue above the air preheater; the nitrogen input pipeline comprises a second nitrogen input pipeline which is connected with the upper part of the air preheater in the tail flue of the boiler and is used for spraying nitrogen to the upper part of the air preheater so as to eliminate flame in the flue above the air preheater, and a second nitrogen control valve is arranged on the second nitrogen input pipeline.
5. The automatic control device for preventing post-combustion of a boiler afterburner as set forth in claim 4, wherein the controller is further configured to control the steam input line and/or the nitrogen input line to inject steam and/or nitrogen into the boiler afterburner based on the temperature signal and/or the flame signal, comprising: If the controller only receives the second temperature signal, controlling the second steam control valve to be opened, so that the second steam input pipeline sprays steam into a flue above the air preheater until the second temperature signal disappears; If the second temperature signal does not disappear, the second flame signal is received, the oxygen content is detected to be larger than an oxygen content preset value, the CO content is detected to be larger than a CO content preset value, the second nitrogen control valve is controlled to be opened, and the second nitrogen input pipeline is enabled to spray nitrogen into a flue above the air preheater until the second temperature signal disappears and the second flame signal disappears.
6. The automatic control device for preventing post-combustion of a boiler afterburner as claimed in claim 1, wherein the preset temperature is 100 ℃.
7. An automatic control method for preventing secondary combustion of a tail flue of a boiler, which is characterized by comprising the following steps: Acquiring the temperature of the flue gas in the tail flue of the boiler through a flue gas temperature detection module, and generating a temperature signal when the temperature of the flue gas is greater than a preset temperature; Detecting whether flame appears in the boiler tail flue or not through a flame detection module, and generating a flame signal when the flame appears in the boiler tail flue; Steam or/and nitrogen is/are controlled to be sprayed into the tail flue of the boiler by the controller according to the temperature signal or/and the flame signal so as to prevent the combustion of flue gas in the tail flue of the boiler; and controlling steam or/and nitrogen to be sprayed into the tail flue of the boiler according to the temperature signal or/and the flame signal, wherein the method comprises the following steps of: when the temperature signal is generated and the flame signal is not generated, controlling steam to be sprayed into the tail flue of the boiler until the temperature signal disappears; When the temperature signal is not disappeared and the flame signal is generated, and the fact that the oxygen content in the boiler tail flue is larger than the oxygen content preset value is detected, the CO content is larger than the CO content preset value, steam and nitrogen are controlled to be sprayed into the boiler tail flue until the temperature signal and the flame signal are both disappeared is detected, the zirconia module is located above an economizer in the boiler tail flue and used for detecting the oxygen content in flue gas, the CO detector is located below an air preheater in the boiler tail flue and used for detecting the CO content in flue gas, the economizer and the air preheater are both located in the boiler tail flue and above the air heater, the economizer is used for heating coal gas through the temperature of flue gas, and the air preheater is all used for heating air through the temperature of flue gas.
8. The automatic control method for preventing secondary combustion of a boiler afterburner as set forth in claim 7, wherein the controlling, by the controller, steam or/and nitrogen to be injected into the boiler afterburner based on the temperature signal or/and the flame signal includes: and when the temperature signal and the flame signal are generated, controlling steam and nitrogen to be sprayed into the tail flue of the boiler until the temperature signal and the flame signal disappear.

Description

Automatic control device and method for preventing secondary combustion of tail flue of boiler Technical Field The embodiment of the invention relates to the technical field of boiler tail flue gas treatment, in particular to an automatic control device and method for preventing secondary combustion of a boiler tail flue. Background In the actual running process of the boiler, when the pressure of the coal gas is suddenly increased, even if a coal gas valve is not operated, the flow of the coal gas is suddenly and greatly increased, and oxygen-deficient combustion is easily caused when the air supply is not timely increased, so that the coal gas is incompletely combusted, unburned CO is brought into a tail flue, and due to the defects of the design and the installation of the boiler, unreasonable dead zones exist, the smoke speed is too low, and a large amount of combustible materials are accumulated in the flue. After a large amount of unburned CO is brought into the tail flue, a large amount of unburned combustible gas can be collected in the tail flue, and secondary combustion of the tail flue is easily caused when the tail flue is not strictly provided with larger air leakage or air leakage occurs in an air preheater, and three elements (combustible materials, air and temperature) of combustion are achieved in the flue. When the secondary combustion of the boiler occurs, the furnace becomes positive pressure, smoke is emitted from the imprecise part of the flue, the current of the induced draft fan is increased, the current swings, the temperature of the main steam and the wall temperature of the superheater are increased, the temperature of the combustion point and the temperature of the smoke exhaust are increased, the steel beam is burned red, the furnace wall is in danger of collapse, and if the furnace wall is improperly treated, serious accidents are caused. Disclosure of Invention The invention provides an automatic control device and method for preventing secondary combustion of a boiler tail flue, so as to eliminate hidden danger of secondary combustion accidents of the boiler tail flue in a sprouting state and ensure safe and stable operation of a boiler. In a first aspect, an embodiment of the present invention provides an automatic control device for preventing secondary combustion in a tail flue of a boiler, including a smoke temperature detection module, a flame detection module, a steam input pipeline, a nitrogen input pipeline, and a controller; The smoke temperature detection module is used for detecting the temperature of smoke in a tail flue of the boiler, and sending a temperature signal to the controller when the temperature of the smoke is greater than a preset temperature; the flame detection module is used for detecting whether flame appears in the boiler tail flue, and when flame appears in the boiler tail flue, a flame signal is generated and sent to the controller; The steam input pipeline is connected with the boiler tail flue and is used for spraying steam into the boiler tail flue so as to reduce the temperature of flue gas in the boiler tail flue; the nitrogen input pipeline is connected with the boiler tail flue and is used for spraying nitrogen into the boiler tail flue so as to eliminate flame in the boiler tail flue; the controller is used for controlling the steam input pipeline or/and the nitrogen input pipeline to spray steam or/and nitrogen into the boiler tail flue according to the temperature signal or/and the flame signal so as to prevent the flue gas in the boiler tail flue from burning. Further, the device also comprises a zirconia module and a CO detector; the zirconia module is positioned above the economizer in the tail flue of the boiler and is used for detecting the oxygen content in the flue gas and sending the oxygen content to the controller; The CO detector is positioned below the air preheater in the tail flue of the boiler and is used for detecting the content of CO in the flue gas and sending the content of CO to the controller. Further, the flue gas temperature detection module comprises a first flue gas temperature detection module which is positioned above the economizer in the tail flue of the boiler and is used for detecting the temperature of flue gas in the flue above the economizer, and when the temperature of the flue gas is greater than a preset temperature, a first temperature signal is sent to the controller; The flame detection module comprises a first flame detection module which is positioned above the economizer in the tail flue of the boiler and is used for detecting whether flame appears in the flue above the economizer, and when flame appears in the flue above the economizer, a first flame signal is generated and sent to the controller; The steam input pipeline comprises a first steam input pipeline, wherein the first steam input pipeline is connected with the upper part of the economizer in the tail flue of the boiler and is use