An on-line leak detection method and system for a hot blast stove heat exchanger

Abstract

The application discloses a kind of hot blast stove heat exchanger on-line leak detection method and system.The leak detection method includes: obtaining the CO concentration in flue gas composition;According to CO concentration and detection parameter, determine whether gas heat exchanger leaks;Wherein, detection parameter includes the pressure resistance loss deviation value between the inlet end and outlet end of gas heat exchanger, the temperature deviation value of heat exchange gas, the air-fuel ratio of furnace and the vault temperature deviation value.Realize the comprehensive and effective on-line leak detection of hot blast stove heat exchanger, can find out in time when gas leakage occurs in heat exchanger, improve the reliability of detection heat exchanger leak detection result, reduce the safety risk caused by gas leakage in heat exchanger, promote the safe operation of hot blast stove system, with good popularization significance.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of waste heat recovery technology of blast furnace hot blast stove, and particularly to an online leak detection method and system for hot blast stove heat exchangers. Background Technology

[0002] The plate heat exchanger for hot blast stoves is a high-efficiency and energy-saving preheater that can preheat coal gas using the flue gas discharged from the hot blast stove. Due to its high heat exchange efficiency, it is currently the most mainstream waste heat recovery equipment for hot blast stoves.

[0003] However, after long-term use, the plate heat exchanger of the hot blast stove may leak due to dew point corrosion causing cracks in the welds of the intermediate plates. This can lead to gas leakage into the flue pipe. If the leaked gas meets the conditions for detonation, it may cause detonation in the flue pipe and chimney, posing a significant production safety hazard. Summary of the Invention

[0004] This invention provides an online leak detection method and system for hot blast stove heat exchangers, which enables online leak detection of hot blast stove heat exchangers and controls the leakage and diffusion of coal gas, thereby reducing the safety risks caused by coal gas leakage in the heat exchanger.

[0005] In a first aspect, embodiments of the present invention provide an online leak detection method for a hot blast stove heat exchanger, comprising:

[0006] Obtain the CO concentration in the flue gas composition within the flue;

[0007] The gas heat exchanger is determined to be leaking based on the CO concentration and detection parameters; wherein, the detection parameters include the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the gas temperature deviation after heat exchange, the air-fuel ratio of the furnace, and the dome temperature deviation.

[0008] Furthermore, after obtaining the CO concentration, the leak detection method further includes:

[0009] If the CO concentration remains greater than or equal to a first threshold within a first preset time period, a first-level alarm will be issued.

[0010] Furthermore, the step of determining whether the gas heat exchanger is leaking based on the CO concentration and detection parameters includes:

[0011] When the CO concentration remains greater than or equal to a first threshold for a first preset time period, if the detection parameters simultaneously satisfy the following: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to a first preset pressure resistance deviation; the temperature deviation of the gas after heat exchange is greater than or equal to a first preset gas temperature deviation; the air-fuel ratio of the furnace is greater than or equal to a first preset air-fuel ratio; and the temperature deviation of the dome is less than or equal to a first preset dome temperature deviation, then it is determined that the gas heat exchanger has a leak.

[0012] Furthermore, after determining that the gas heat exchanger has a leak, the leak detection method further includes:

[0013] When the CO concentration remains greater than or equal to the second threshold and less than the third threshold for a second preset time period, if the detection parameters simultaneously satisfy: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the second preset pressure resistance deviation, the temperature deviation of the gas after heat exchange is greater than or equal to the second preset gas temperature deviation, the air-fuel ratio of the furnace is greater than or equal to the second preset air-fuel ratio, and the temperature deviation of the dome is less than or equal to the second preset dome temperature deviation, then a second-level alarm will be issued, and the operator will be reminded to conduct on-site confirmation and warning.

[0014] Furthermore, after issuing the second-level alarm, the leak detection method further includes:

[0015] When the CO concentration continues to be greater than the third threshold within a third preset time period, if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the third preset pressure resistance deviation, the temperature deviation of the gas after heat exchange is greater than or equal to the third preset gas temperature deviation, the air-fuel ratio of the furnace is greater than or equal to the third preset air-fuel ratio, and the temperature deviation of the dome is less than or equal to the third preset dome temperature deviation, then a third-level alarm is issued.

[0016] The hot blast stove is shut down, and the flue pipe of the hot blast stove is purged with nitrogen.

[0017] Furthermore, after the hot blast stove is shut down, the online leak detection also includes:

[0018] If the CO concentration remains greater than or equal to the third threshold for a fourth preset time period, a fourth-level alarm will be issued, and the connection between the gas pipeline of the hot blast stove and the external gas pipeline network will be cut off.

[0019] Furthermore, the first threshold is 5000 PPm, the second threshold is 10000 PPm, and the third threshold is 20000 PPm;

[0020] The first preset pressure resistance deviation value ranges from 0.9 to 0.8, the second preset pressure resistance deviation value ranges from 0.8 to 0.75, and the third preset pressure resistance deviation value ranges from 0.75 to 0.65.

[0021] The first preset gas temperature deviation value ranges from 1.025 to 1.075, the second preset gas temperature deviation value ranges from 1.08 to 1.10, and the third preset gas temperature deviation value ranges from 1.10 to 1.15.

[0022] The first preset air-fuel ratio ranges from 1.05 to 1.15, the second preset air-fuel ratio ranges from 1.15 to 1.18, and the third preset air-fuel ratio ranges from 1.18 to 1.20.

[0023] The first preset arch temperature deviation value ranges from 0.99 to 0.97, the second preset arch temperature deviation value ranges from 0.97 to 0.95, and the third preset arch temperature deviation value ranges from 0.95 to 0.92.

[0024] Secondly, embodiments of the present invention also provide an online leak detection system for a hot blast stove heat exchanger, used to perform the above-described online leak detection method for a hot blast stove heat exchanger, the online leak detection system comprising a hot blast stove subsystem, a detection module, and a control subsystem;

[0025] The detection module is used to obtain the CO concentration and detection parameters in the flue gas composition in the flue of the hot blast stove subsystem; wherein, the detection parameters include the pressure resistance deviation value between the inlet and outlet of the gas heat exchanger, the temperature deviation value of the gas after heat exchange, the air-fuel ratio of the furnace and the temperature deviation value of the dome.

[0026] The control subsystem is used to determine whether the gas heat exchanger is leaking based on the CO concentration and the detection parameters, and to control the hot air furnace subsystem to perform corresponding operations after determining that the gas heat exchanger is leaking.

[0027] Furthermore, the hot air furnace subsystem includes a main gas pipeline, a gas pipeline bypass, a heat exchanger, a hot air furnace, a flue, and an alarm module;

[0028] The main gas pipeline input end is connected to an external gas pipeline network, and the output end is connected to the hot air furnace, used to transmit gas to the hot air furnace;

[0029] The gas pipe bypass input end is connected to the main gas pipe, and the output end is connected to the hot air furnace, which is used to transmit the preheated gas to the hot air furnace.

[0030] The flue input end is connected to the hot air furnace outlet, and the output end is connected to the chimney, for transmitting flue gas to the chimney;

[0031] The heat exchanger includes a gas heat exchanger, a flue gas heat exchanger, and a heat exchange plate. The gas heat exchanger is located on the gas pipeline bypass, and the flue gas heat exchanger is located on the flue pipe. The gas heat exchanger and the flue gas heat exchanger are in contact through the heat exchange plate.

[0032] The control module is also used to send corresponding alarm commands to the alarm module based on the CO concentration and the detection parameters.

[0033] The alarm module sends corresponding alarm information according to the alarm command.

[0034] Furthermore, the detection module includes:

[0035] A flue gas analyzer is used to detect the content of various components in the flue gas after it has passed through the flue gas heat exchanger, including the CO concentration.

[0036] The first pressure gauge is installed at the inlet end of the gas heat exchanger and is used to detect the gas pressure at the inlet end of the gas heat exchanger.

[0037] The second pressure gauge is installed at the outlet end of the gas heat exchanger and is used to detect the gas pressure at the outlet end of the gas heat exchanger.

[0038] A thermometer is installed at the outlet end of the gas heat exchanger to detect the gas temperature at the outlet end of the gas heat exchanger.

[0039] A hot blast stove air-fuel ratio detector is installed on the hot blast stove to detect the air flow rate and gas flow rate in the hot blast stove;

[0040] A thermocouple for the hot blast stove arch is installed at the arch of the hot blast stove and is used to detect the temperature of the hot blast stove arch.

[0041] The gas pipeline bypass is also equipped with a gas heat exchanger inlet valve and a gas heat exchanger outlet valve; the gas heat exchanger inlet valve is located at the input end of the gas pipeline bypass and is used to control the gas entering the gas pipeline bypass; the gas heat exchanger outlet valve is located at the output end of the gas pipeline bypass and is used to control the preheated gas entering the hot blast stove.

[0042] The main gas pipeline is also equipped with a gas shut-off valve, a gas regulating valve, and a main gas line valve. The gas shut-off valve is located at the connection between the main gas pipeline and the external gas pipeline network, and is used to shut off the connection between the main gas pipeline and the external gas pipeline network. The gas regulating valve is located between the gas shut-off valve and the node where the gas pipeline bypass connects to the main gas pipeline, and is used to regulate the gas flow rate. The main gas line valve is located at the connection between the main gas pipeline and the hot blast stove, and is used to control the gas from the main gas pipeline to enter the hot blast stove.

[0043] The hot air furnace system also includes a flue gas purging module, located on the side of the flue gas near the hot air furnace, used to drive away and dilute the CO remaining in the flue gas.

[0044] The technical solution of this embodiment discloses an online leak detection method for hot blast stove heat exchangers. By acquiring the CO concentration in the flue gas composition, and determining whether the heat exchanger is leaking based on the real-time changes in CO concentration, pressure loss deviation between the inlet and outlet of the gas heat exchanger, temperature deviation of the gas after heat exchange, air-fuel ratio, and dome temperature deviation, this method achieves comprehensive and effective online leak detection of hot blast stove heat exchangers. It can detect gas leaks in the heat exchanger in a timely manner, improves the reliability of leak detection results, reduces the safety risks caused by gas leaks in the heat exchanger, and promotes the safe operation of the hot blast stove system. Attached Figure Description

[0045] Figure 1 This is a flowchart of an online leak detection method for a hot blast stove heat exchanger provided in Embodiment 1 of the present invention;

[0046] Figure 2 This is a schematic diagram of a hot blast stove heat exchanger system provided in Embodiment 1 of the present invention;

[0047] Figure 3 This is a flowchart of an online leak detection method for a hot blast stove heat exchanger provided in Embodiment 2 of the present invention;

[0048] Figure 4 A flowchart of another online leak detection method for a hot blast stove heat exchanger provided in Embodiment 2 of the present invention;

[0049] Figure 5 This is a schematic diagram of an online leak detection system for a hot blast stove heat exchanger provided in Embodiment 3 of the present invention;

[0050] Figure 6 This is a schematic diagram of an online leak detection system for a hot blast stove heat exchanger provided in Embodiment 3 of the present invention;

[0051] Figure 7 This is a schematic diagram of another online leak detection system for a hot blast stove heat exchanger provided in Embodiment 3 of the present invention. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0053] Example 1

[0054] Figure 1 This is a flowchart of an online leak detection method for a hot blast stove heat exchanger provided in Embodiment 1 of the present invention. This embodiment is applicable to the detection of leaks in plate heat exchangers of hot blast stoves. The method can be executed by an online leak detection system for hot blast stove heat exchangers, and specifically includes the following steps:

[0055] S110. Obtain the CO concentration in the flue gas composition within the flue;

[0056] in, Figure 2 This is a schematic diagram of a hot blast stove heat exchanger system provided in Embodiment 1 of the present invention, as shown below. Figure 2 As shown, in the hot blast stove heat exchanger system, the flue is the exhaust duct of the hot blast stove. The hot blast stove discharges the high-temperature flue gas after the combustion of coal gas from the flue to the chimney. Due to incomplete combustion, the flue gas may still contain low concentrations of gases such as CO and O2. After the high-temperature flue gas discharged from the hot blast stove passes through the heat exchanger, the coal gas temperature is lower than the flue gas temperature, which can preheat the coal gas, thereby achieving the effects of saving coal gas, increasing the combustion temperature of coal gas, and increasing the combustion speed of coal gas.

[0057] For details, please refer to [link / reference]. Figure 2The gas pipeline bypass preheats the gas in the bypass via a gas heat exchanger. During this preheating process, the valves in the main gas pipeline are closed, and the hot blast stove only receives gas through the bypass. The CO concentration in the flue gas should be measured on the flue pipe between the flue gas heat exchanger and the chimney, allowing for the determination of any gas leakage in the heat exchanger. The heat exchanger consists of two parts: the gas pipeline side and the flue gas pipeline side, which can be referred to as the gas heat exchanger and the flue gas heat exchanger, respectively. These are located in the flue and the gas pipeline bypass, separated by heat exchange plates. Preheating of the gas is achieved by the flow of gas and flue gas within these heat exchangers. The main components of coal gas are carbon monoxide, hydrogen, and methane. If cracks appear in the welds of the heat exchange plates, it can lead to gas leaks in the coal gas heat exchanger. By obtaining the CO concentration in the flue gas from the duct before the chimney and comparing it with the CO concentration in normal flue gas, it can be determined whether a leak exists in the coal gas heat exchanger. Furthermore, see [link to relevant documentation]. Figure 2 Multiple on / off valves and regulating valves can be installed in the gas pipeline bypass and the main gas pipeline to control the gas entering the gas pipeline bypass and the main gas pipeline.

[0058] S120. Determine whether the gas heat exchanger is leaking based on the CO concentration and detection parameters; among which, the detection parameters include the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio of the furnace, and the temperature deviation of the dome.

[0059] For details, see Figure 2The pressure resistance deviation between the inlet and outlet of the gas heat exchanger can be obtained by measuring the pressure values ​​at the inlet and outlet of the gas heat exchanger using pressure gauges installed at the inlet and outlet. The pressure resistance deviation is then calculated by observing the changes in these pressure values. This deviation is represented by the ratio between the outlet pressure and the inlet pressure. The temperature deviation of the gas after heat exchange is detected by a thermometer installed at the outlet of the gas heat exchanger. This temperature deviation is represented by the ratio between the outlet temperature and the temperature of the gas after normal heat exchange, and the calculated temperature deviation is obtained. Normal heat exchange refers to heat exchange performed without gas leakage. The air-fuel ratio for furnace operation is determined by measuring the air and gas flow rates using existing air and gas flow meters in the hot blast stove. The air-fuel ratio can be characterized by the ratio of air flow rate to gas flow rate, and is calculated accordingly. An arch thermocouple is installed on the arch of the hot blast stove to monitor its temperature in real time. The arch temperature deviation is characterized by the ratio of the detected arch temperature to the normal arch temperature, and is calculated accordingly. Under normal furnace operation conditions, the CO concentration in the flue gas is ≤2000 ppm.

[0060] When a gas heat exchanger leaks, the following scenarios will occur according to the process principle: ① Gas enters the flue pipe, and the online flue gas analyzer installed on the flue pipe can detect the CO content in the flue gas; ② The pressure at the outlet of the gas heat exchanger is lower than that at the inlet, and the pressure resistance deviation value decreases; ③ With the flue gas volume (high enthalpy gas heat transfer medium) entering the gas heat exchanger remaining constant, the temperature of the furnace gas after heat exchange increases after the leakage decreases; ④ With the gas volume leakage decreasing, the air-fuel ratio increases while the furnace air remains constant, and the furnace dome temperature decreases. Therefore, based on the CO concentration, the pressure resistance deviation value between the inlet and outlet of the gas heat exchanger, the temperature deviation value of the gas after heat exchange, the furnace air-fuel ratio, and the dome temperature deviation values, a comprehensive online judgment can be made regarding whether the gas heat exchanger is leaking, thereby improving production safety.

[0061] The technical solution of this embodiment discloses an online leak detection method for hot blast stove heat exchangers. By acquiring the CO concentration in the flue gas composition, and determining whether the heat exchanger is leaking based on the real-time changes in CO concentration, pressure loss deviation between the inlet and outlet of the gas heat exchanger, temperature deviation of the gas after heat exchange, air-fuel ratio, and dome temperature deviation, this method achieves comprehensive and effective online leak detection of hot blast stove heat exchangers. It can detect gas leaks in the heat exchanger in a timely manner, improves the reliability of leak detection results, reduces the safety risks caused by gas leaks in the heat exchanger, and promotes the safe operation of the hot blast stove system.

[0062] Example 2

[0063] Figure 3 This is a flowchart of an online leak detection method for a hot blast stove heat exchanger provided in Embodiment 2 of the present invention. This embodiment further supplements the online leak detection method for the hot blast stove heat exchanger based on the above embodiments, and after obtaining the CO concentration in the flue gas composition, it also includes the following steps:

[0064] S210. If the CO concentration continues to be greater than or equal to the first threshold within the first preset time, a first-level alarm shall be issued.

[0065] Specifically, after obtaining the CO concentration in the flue gas, the system determines whether the CO concentration remains above or equal to a first threshold for a first preset time period. This prevents false alarms due to accidental increases in CO concentration. When the CO concentration remains above or equal to the first threshold for the first preset time period, it can be determined that the CO concentration in the flue gas is too high, thus triggering a first-level alarm to alert operators of the increased CO concentration in the flue gas duct for confirmation. The first-level alarm is the initial alarm, used to alert operators of a potential risk of gas leakage.

[0066] Optionally, the first threshold can be 5000 ppm. S1201. When the CO concentration is continuously greater than or equal to the first threshold within a first preset time, if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the first preset pressure resistance deviation, the gas temperature deviation after heat exchange is greater than or equal to the first preset gas temperature deviation, the furnace air-fuel ratio is greater than or equal to the first preset air-fuel ratio, and the dome temperature deviation is less than or equal to the first preset dome temperature deviation, then it is determined that there is a leak in the gas heat exchanger.

[0067] Specifically, when the CO concentration remains greater than or equal to a first threshold for a first preset time period, and the pressure loss deviation between the inlet and outlet of the gas heat exchanger is less than or equal to a first preset pressure loss deviation, and the temperature deviation of the gas after heat exchange is greater than or equal to a first preset gas temperature deviation, a leak in the gas heat exchanger can be determined. When the furnace air-fuel ratio is greater than or equal to a first preset air-fuel ratio, and the dome temperature deviation is less than or equal to a first preset dome temperature deviation, a reduction in the amount of gas entering the hot blast stove can be determined. When all four detection parameters meet the preset conditions, a leak in the gas heat exchanger can be determined. When any one of the four detection parameters fails to meet the preset conditions, a leak in the gas heat exchanger cannot be accurately determined; the high CO concentration in the flue gas duct may be due to other reasons. Analyzing the pressure loss deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the furnace air-fuel ratio, and the dome temperature deviation can improve the accuracy of determining whether the heat exchanger is leaking.

[0068] Optionally, the range of the first preset pressure resistance deviation value is 0.9-0.8, the range of the first preset gas temperature deviation value is 1.025-1.075, the range of the first preset air-fuel ratio is 1.05-1.15, and the range of the first preset dome temperature deviation value is 0.99-0.97.

[0069] Figure 4 This is a flowchart of another online leak detection method for a hot blast stove heat exchanger provided in Embodiment 2 of the present invention. After determining that there is a leak in the gas heat exchanger, the leak detection method further includes:

[0070] S310. When the CO concentration is continuously greater than or equal to the second threshold and less than the third threshold within the second preset time, if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the second preset pressure resistance deviation, the gas temperature deviation after heat exchange is greater than or equal to the second preset gas temperature deviation, the furnace air-fuel ratio is greater than or equal to the second preset air-fuel ratio, and the dome temperature deviation is less than or equal to the second preset dome temperature deviation, then a second-level alarm will be issued, and the operator will be reminded to conduct on-site confirmation and warning.

[0071] Specifically, the level 2 alarm indicates a higher level of danger than the level 1 alarm. When the CO concentration remains above or equal to the second threshold and below the third threshold for a second preset time period, it indicates that the CO concentration in the flue gas pipeline is too high. When the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio of the furnace, and the temperature deviation of the dome meet the preset conditions, it can be determined that the excessive CO concentration in the flue gas pipeline is caused by a leak in the gas heat exchanger. Therefore, a higher level alarm needs to be issued to remind the operators to conduct on-site confirmation of whether there is a major gas leak and to be alerted to potential dangers.

[0072] Optionally, the second threshold can be 10000 ppm, the range of the second preset pressure resistance deviation value is 0.8-0.75, the range of the second preset gas temperature deviation value is 1.08-1.10, the range of the second preset air-fuel ratio is 1.15-1.18, and the range of the second preset dome temperature deviation value is 0.97-0.95.

[0073] S320. When the CO concentration continues to be greater than the third threshold within the third preset time period, if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the third preset pressure resistance deviation, the gas temperature deviation after heat exchange is greater than or equal to the third preset gas temperature deviation, the furnace air-fuel ratio is greater than or equal to the third preset air-fuel ratio, and the dome temperature deviation is less than or equal to the third preset dome temperature deviation, then a third-level alarm is issued; the hot blast stove is shut down, and the flue pipe of the hot blast stove is purged with nitrogen.

[0074] Specifically, when the CO concentration remains above the third threshold for a third preset time period, it indicates that the CO concentration in the flue gas pipeline is particularly high. When the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio of the furnace, and the temperature deviation of the dome meet the preset conditions, it can be determined that the CO concentration in the flue gas pipeline is particularly high due to a leak in the gas heat exchanger. Therefore, a higher level alarm needs to be issued. The level 3 alarm indicates a greater degree of danger than the level 2 alarm. At the same time, in order to avoid an explosion, the hot blast stove should be shut down, the valve of the pipeline where the gas heat exchanger is located should be closed, and the flue gas pipeline of the hot blast stove should be purged with nitrogen through the hot blast stove flue gas purging module to drive away and dilute the CO remaining in the flue gas pipeline and suppress any possible explosions in the flue gas.

[0075] Optionally, the third threshold can be 20000 ppm, the range of the third preset pressure resistance deviation value is 0.75 to 0.65, the range of the third preset gas temperature deviation value is 1.10 to 1.15, the range of the third preset air-fuel ratio is 1.18 to 1.20, and the range of the third preset dome temperature deviation value is 0.95 to 0.92.

[0076] S330. After the hot blast stove is shut down, if the CO concentration continues to be greater than or equal to the third threshold within a fourth preset time, a fourth-level alarm will be issued and the connection between the gas pipeline of the hot blast stove and the external gas pipeline network will be cut off.

[0077] Specifically, after the hot blast stove is shut down, if the CO concentration remains greater than or equal to the third threshold for a fourth preset time period, it indicates that the valve in the gas pipeline cannot be completely closed, resulting in a large amount of gas still leaking from the gas heat exchanger into the flue. This causes the CO concentration in the flue to remain very high, so a fourth-level alarm needs to be issued to remind the operators of the dangerous situation. The danger level indicated by the fourth-level alarm is greater than that of the third-level alarm, and the connection between the gas pipeline of the hot blast stove and the external gas pipeline network is cut off. At this point, the external gas pipeline network is isolated from the hot blast stove combustion gas pipeline, i.e., the heat exchanger, thus controlling the leakage and diffusion of external gas.

[0078] The technical solution of this embodiment involves online detection and comprehensive judgment of the CO concentration in the flue gas, the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio of the furnace, and the temperature deviation of the dome. Based on the judgment results, different levels of alarms are issued. When the danger level is high, the hot blast stove is shut down, and the flue pipe of the hot blast stove is purged with nitrogen to control the occurrence of explosions. By cutting off the connection between the gas pipeline of the hot blast stove and the external gas pipeline network, the leakage and diffusion of external gas are controlled, thereby achieving timely detection, timely alarm, timely shut-off of relevant valves, control of gas leakage and diffusion, and promoting the safe operation of the hot blast stove system.

[0079] Example 3

[0080] Figure 5 This is a schematic diagram of an online leak detection system for a hot blast stove heat exchanger provided in Embodiment 3 of the present invention. This embodiment can be based on the above embodiments and used to execute the online leak detection method for the hot blast stove heat exchanger described above, such as... Figure 5 As shown, the online leak detection system includes a hot blast stove subsystem 410, a detection module 420, and a control subsystem 430. The detection module 420 is used to acquire the CO concentration and detection parameters in the flue gas composition in the flue of the hot blast stove subsystem 410. The detection parameters include the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio, and the dome temperature deviation. The control subsystem 430 is used to determine whether the gas heat exchanger is leaking based on the CO concentration and detection parameters, and to control the hot blast stove subsystem 410 to perform corresponding operations after determining that the gas heat exchanger is leaking.

[0081] Specifically, the hot blast stove subsystem 410 includes equipment such as gas pipes, flue gas pipes, heat exchangers, the hot blast stove itself, and various valves. The hot blast stove subsystem 410 preheats the gas supplied from the gas pipes through the heat exchanger, thereby saving gas, increasing the combustion temperature, and improving the combustion speed during operation. The detection module 420 may include various detection devices for measuring the CO concentration in the flue gas, the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio, and the dome temperature deviation. These detection devices are installed at various detection points in the hot blast stove system 410 to obtain various parameters during operation, such as the pressure resistance deviation between the inlet and outlet of the gas heat exchanger. The pressure values ​​at the inlet and outlet of the gas heat exchanger can be measured by pressure gauges installed at the inlet and outlet of the gas heat exchanger in the hot blast stove subsystem 410. The pressure resistance deviation value can then be obtained by observing the changes in the pressure values ​​at the inlet and outlet of the gas heat exchanger. The control subsystem 430 can acquire the detection data from the detection module 420. Based on the real-time changes in the CO concentration, the pressure resistance deviation value between the inlet and outlet of the gas heat exchanger, the temperature deviation value of the gas after heat exchange, the air-fuel ratio of the furnace, and the temperature deviation value of the dome detected by the detection module 420, it can determine whether the gas heat exchanger is leaking. When a leak is detected in the gas heat exchanger, the control subsystem 410 can perform corresponding operations, such as closing relevant valves in the hot blast stove subsystem 410 to control gas leakage, or issuing an alarm in the hot blast stove subsystem 410 to alert the operator of the danger.

[0082] The technical solution of this embodiment discloses an online leak detection system for hot blast stove heat exchangers, including a hot blast stove subsystem, a detection module, and a control subsystem. The detection module acquires the CO concentration and detection parameters in the flue gas composition within the flue. These detection parameters include the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio, and the dome temperature deviation. The control subsystem determines whether the heat exchanger is leaking based on the CO concentration and detection parameters, achieving comprehensive and effective online leak detection of the hot blast stove heat exchanger. This system can promptly detect gas leaks in the heat exchanger, improving the reliability of leak detection results, reducing the safety risks caused by gas leaks in the heat exchanger, and promoting the safe operation of the hot blast stove system. It has significant potential for widespread application.

[0083] Furthermore, Figure 6 This is a schematic diagram of an online leak detection system for a hot blast stove heat exchanger provided in Embodiment 3 of the present invention. Figure 6 As shown, the hot air furnace subsystem includes a main gas pipeline 4101, a gas pipeline bypass 4102, a heat exchanger 4103, a hot air furnace 4104, and a flue 4105.

[0084] The main gas pipeline 4101 has its input end connected to an external gas pipeline network and its output end connected to a hot air furnace, used to transmit gas to the hot air furnace 4104.

[0085] The gas pipe bypass 4102 has its input end connected to the main gas pipe and its output end connected to the hot air furnace, and is used to transfer the preheated gas to the hot air furnace 4104.

[0086] The flue 4105 has its inlet end connected to the outlet of the hot air furnace 4104 and its outlet end connected to the chimney, and is used to transmit flue gas to the chimney.

[0087] The heat exchanger 4103 includes a gas heat exchanger 41031, a flue gas heat exchanger 41032, and a heat exchange plate 41033. The gas heat exchanger 41031 is located on the gas pipe bypass 4102, and the flue gas heat exchanger 41032 is located on the flue duct 4103. The gas heat exchanger 41031 and the flue gas heat exchanger 41032 are in contact through the heat exchange plate 41033.

[0088] Optionally, the control module is also used to send corresponding alarm commands to the alarm module based on the CO concentration and detection parameters;

[0089] The hot air furnace system 410 also includes an alarm module, which sends corresponding alarm information according to the alarm command.

[0090] Optional, Figure 7 This is a schematic diagram of another online leak detection system for a hot blast stove heat exchanger provided in Embodiment 3 of the present invention, as shown below. Figure 7 As shown, the detection module 420 in the online leak detection system for hot blast stove heat exchangers includes: a flue gas analyzer 4201, used to detect the content of each component in the flue gas after it passes through the flue gas heat exchanger, including the CO concentration.

[0091] The first pressure gauge 4202 is installed at the inlet end of the gas heat exchanger 41032 and is used to detect the gas pressure at the inlet end of the gas heat exchanger 41031.

[0092] The second pressure gauge 4203 is installed at the outlet end of the gas heat exchanger 41032 and is used to detect the gas pressure at the outlet end of the gas heat exchanger 41031.

[0093] Thermometer 4204 is installed at the outlet end of the gas heat exchanger 41032 and is used to detect the gas temperature at the outlet end of the gas heat exchanger 41031.

[0094] A hot blast stove air-fuel ratio detector 4205 is installed on the hot blast stove 4104 and is used to detect the air flow rate and gas flow rate in the hot blast stove 4104.

[0095] A hot blast stove dome thermocouple 4206 is installed at the dome of the hot blast stove 4104 to detect the temperature of the dome of the hot blast stove 4104.

[0096] Specifically, the pressure loss deviation value is obtained by measuring the data from the flue gas analyzer 4201, the first pressure gauge 4202, the second pressure gauge 4203, the thermometer 4204, the hot blast stove air-fuel ratio detector 4205, and the hot blast stove dome thermocouple 4206, and then by measuring the pressure changes at the inlet and outlet of the gas heat exchanger 41031. The pressure loss deviation value can be characterized by the ratio between the pressure at the outlet of the gas heat exchanger and the pressure at the inlet of the gas heat exchanger. The gas temperature deviation value after heat exchange is detected by the thermometer installed at the outlet of the gas heat exchanger. The gas temperature deviation value can be characterized by the ratio between the temperature at the outlet of the gas heat exchanger and the gas temperature after normal heat exchange, and the gas temperature deviation value is calculated. Here, normal heat exchange refers to heat exchange performed without gas leakage. The furnace air-fuel ratio is determined by measuring the air and gas flow rates using existing air and gas flow meters in the hot blast stove. The furnace air-fuel ratio can be characterized by the ratio of air flow rate to gas flow rate, and is calculated accordingly. An arch thermocouple is installed on the arch of the hot blast stove to monitor the arch temperature in real time. The arch temperature deviation can be characterized by the ratio of the detected hot blast stove arch temperature to the normal hot blast stove arch temperature, and is calculated accordingly. This allows the control subsystem 430 to determine whether the gas heat exchanger is leaking based on the CO concentration and detection parameters.

[0097] See Figure 7 The gas pipeline bypass 4102 is also equipped with a gas heat exchanger inlet valve 41021 and a gas heat exchanger outlet valve 41022; the gas heat exchanger inlet valve 41021 is located at the input end of the gas pipeline bypass 4102 and is used to control the gas entering the gas pipeline bypass 4102; the gas heat exchanger outlet valve 41022 is located at the output end of the gas pipeline bypass 4102 and is used to control the preheated gas entering the hot blast stove 4104.

[0098] The main gas pipeline 4101 is also equipped with a gas shut-off valve 41011, a gas regulating valve 41012, and a main gas pipeline valve 41013. The gas shut-off valve 41011 is located at the connection between the main gas pipeline 4101 and the external gas pipeline network, and is used to shut off the connection between the main gas pipeline 4101 and the external gas pipeline network. The gas regulating valve 41012 is located between the gas shut-off valve 41012 and the node connecting the gas pipeline bypass 4102 to the main gas pipeline 4101, and is used to regulate the flow rate of gas. The main gas pipeline valve 41013 is located at the connection between the main gas pipeline 4101 and the hot blast stove 4104, and is used to control the gas from the main gas pipeline 4101 to enter the hot blast stove 4104.

[0099] The hot air furnace system also includes a flue gas purging module 4106, located on the side of the flue gas near the hot air furnace, which is used to drive away and dilute the CO remaining in the flue gas.

[0100] Furthermore, the control subsystem 430 is used to determine whether the gas heat exchanger is leaking based on the CO concentration and detection parameters, including:

[0101] After acquiring the CO concentration and detection parameters, if the CO concentration continues to be greater than or equal to the first threshold within a first preset time, the control subsystem 430 will issue a first-level alarm.

[0102] When the CO concentration is continuously greater than or equal to the first threshold within a first preset time period, if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the first preset pressure resistance deviation, the gas temperature deviation after heat exchange is greater than or equal to the first preset gas temperature deviation, the furnace air-fuel ratio is greater than or equal to the first preset air-fuel ratio, and the dome temperature deviation is less than or equal to the first preset dome temperature deviation, then it is determined that there is a leak in the gas heat exchanger.

[0103] After determining that there is a leak in the gas heat exchanger, if the CO concentration is continuously greater than or equal to the second threshold and less than the third threshold within the second preset time, and if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the second preset pressure resistance deviation, the gas temperature deviation after heat exchange is greater than or equal to the second preset gas temperature deviation, the air-fuel ratio of the furnace is greater than or equal to the second preset air-fuel ratio, and the dome temperature deviation is less than or equal to the second preset dome temperature deviation, then a second-level alarm will be issued, and the operator will be reminded to conduct on-site confirmation and warning.

[0104] After issuing a second-level alarm, if the CO concentration continues to exceed the third threshold within a third preset time period, and if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the third preset pressure resistance deviation, the gas temperature deviation after heat exchange is greater than or equal to the third preset gas temperature deviation, the furnace air-fuel ratio is greater than or equal to the third preset air-fuel ratio, and the dome temperature deviation is less than or equal to the third preset dome temperature deviation, then a third-level alarm will be issued; the hot blast stove will be shut down, and the flue pipe of the hot blast stove will be purged with nitrogen.

[0105] After the hot blast stove is shut down, the control subsystem 430 is also used for:

[0106] If the CO concentration remains greater than or equal to the third threshold for a fourth preset time period, a fourth-level alarm will be issued, and the connection between the gas pipeline of the hot blast stove and the external gas pipeline network will be cut off.

[0107] The technical solution of this embodiment uses a detection module to perform online detection of the CO concentration in the flue gas, the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the temperature deviation of the gas after heat exchange, the air-fuel ratio of the furnace, and the temperature deviation of the dome. The control subsystem determines whether the gas heat exchanger is leaking based on the CO concentration and detection parameters, and makes a comprehensive judgment. Based on the judgment result, different levels of alarms are issued. When the danger level is high, the hot blast stove is shut down and the flue pipe of the hot blast stove is purged with nitrogen to prevent explosions. By cutting off the connection between the gas pipeline of the hot blast stove and the external gas network, the leakage and diffusion of external gas are controlled. This achieves timely detection, timely alarm, timely closure of relevant valves, control of gas leakage and diffusion, and promotes the safe operation of the hot blast stove system, which has great potential for widespread application.

[0108] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An on-line leak detection method for a hot blast stove heat exchanger, characterized by, include: Obtain the CO concentration in the flue gas composition within the flue; The gas heat exchanger is determined to be leaking based on the CO concentration and detection parameters; wherein, the detection parameters include the pressure resistance deviation between the inlet and outlet of the gas heat exchanger, the gas temperature deviation after heat exchange, the air-fuel ratio of the furnace, and the dome temperature deviation. After obtaining the CO concentration, the leak detection method further includes: If the CO concentration remains greater than or equal to a first threshold within a first preset time period, a first-level alarm will be issued. The step of determining whether the gas heat exchanger is leaking based on the CO concentration and detection parameters includes: When the CO concentration remains greater than or equal to a first threshold for a first preset time period, if the detection parameters simultaneously satisfy the following: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to a first preset pressure resistance deviation; the temperature deviation of the gas after heat exchange is greater than or equal to a first preset gas temperature deviation; the air-fuel ratio of the furnace is greater than or equal to a first preset air-fuel ratio; and the temperature deviation of the dome is less than or equal to a first preset dome temperature deviation, then it is determined that the gas heat exchanger has a leak.

2. The method according to claim 1, wherein After determining that the gas heat exchanger is leaking, the leak detection method further includes: When the CO concentration remains greater than or equal to the second threshold and less than the third threshold for a second preset time period, if the detection parameters simultaneously satisfy: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the second preset pressure resistance deviation, the temperature deviation of the gas after heat exchange is greater than or equal to the second preset gas temperature deviation, the air-fuel ratio of the furnace is greater than or equal to the second preset air-fuel ratio, and the temperature deviation of the dome is less than or equal to the second preset dome temperature deviation, then a second-level alarm will be issued, and the operator will be reminded to conduct on-site confirmation and warning.

3. The online leak detection method for a hot blast stove heat exchanger according to claim 2, characterized in that, After issuing the second-level alarm, the leak detection method further includes: When the CO concentration continues to be greater than the third threshold within a third preset time period, if the detection parameters simultaneously meet the following conditions: the pressure resistance deviation between the inlet and outlet of the gas heat exchanger is less than or equal to the third preset pressure resistance deviation, the temperature deviation of the gas after heat exchange is greater than or equal to the third preset gas temperature deviation, the air-fuel ratio of the furnace is greater than or equal to the third preset air-fuel ratio, and the temperature deviation of the dome is less than or equal to the third preset dome temperature deviation, then a third-level alarm is issued. The hot blast stove is shut down, and the flue pipe of the hot blast stove is purged with nitrogen.

4. The online leak detection method for a hot blast stove heat exchanger according to claim 3, characterized in that, After the hot blast stove is shut down, the online leak detection also includes: If the CO concentration remains greater than or equal to the third threshold for a fourth preset time period, a fourth-level alarm will be issued, and the connection between the gas pipeline of the hot blast stove and the external gas pipeline network will be cut off.

5. The online leak detection method for a hot blast stove heat exchanger according to claim 3, characterized in that, The first threshold is 5000 PPm, the second threshold is 10000 PPm, and the third threshold is 20000 PPm; The first preset pressure resistance deviation value ranges from 0.9 to 0.8, the second preset pressure resistance deviation value ranges from 0.8 to 0.75, and the third preset pressure resistance deviation value ranges from 0.75 to 0.

65. The first preset gas temperature deviation value ranges from 1.025 to 1.075, the second preset gas temperature deviation value ranges from 1.08 to 1.10, and the third preset gas temperature deviation value ranges from 1.10 to 1.

15. The first preset air-fuel ratio ranges from 1.05 to 1.15, the second preset air-fuel ratio ranges from 1.15 to 1.18, and the third preset air-fuel ratio ranges from 1.18 to 1.

20. The first preset arch temperature deviation value ranges from 0.99 to 0.97, the second preset arch temperature deviation value ranges from 0.97 to 0.95, and the third preset arch temperature deviation value ranges from 0.95 to 0.

92.

6. An online leak detection system for a hot blast stove heat exchanger, characterized in that, The method for online leak detection of a hot blast stove heat exchanger according to any one of claims 1-5, wherein the online leak detection system includes a hot blast stove subsystem, a detection module, and a control subsystem; The detection module is used to obtain the CO concentration and detection parameters in the flue gas composition in the flue of the hot blast stove subsystem; wherein, the detection parameters include the pressure resistance deviation value between the inlet and outlet of the gas heat exchanger, the temperature deviation value of the gas after heat exchange, the air-fuel ratio of the furnace and the temperature deviation value of the dome. The control subsystem is used to determine whether the gas heat exchanger is leaking based on the CO concentration and the detection parameters, and to control the hot air furnace subsystem to perform corresponding operations after determining that the gas heat exchanger is leaking.

7. The online leak detection system for hot blast stove heat exchangers according to claim 6, characterized in that, The hot air furnace subsystem includes a main gas pipeline, a gas pipeline bypass, a heat exchanger, a hot air furnace, a flue, and an alarm module. The main gas pipeline input end is connected to an external gas pipeline network, and the output end is connected to the hot air furnace, used to transmit gas to the hot air furnace; The gas pipe bypass input end is connected to the main gas pipe, and the output end is connected to the hot air furnace, which is used to transmit the preheated gas to the hot air furnace. The flue input end is connected to the hot air furnace outlet, and the output end is connected to the chimney, for transmitting flue gas to the chimney; The heat exchanger includes a gas heat exchanger, a flue gas heat exchanger, and a heat exchange plate. The gas heat exchanger is located on the gas pipeline bypass, and the flue gas heat exchanger is located on the flue pipe. The gas heat exchanger and the flue gas heat exchanger are in contact through the heat exchange plate.

8. The online leak detection system for hot blast stove heat exchangers according to claim 7, characterized in that, The detection module includes: A flue gas analyzer is used to detect the content of various components in the flue gas after it has passed through the flue gas heat exchanger, including the CO concentration. The first pressure gauge is installed at the inlet end of the gas heat exchanger and is used to detect the gas pressure at the inlet end of the gas heat exchanger. The second pressure gauge is installed at the outlet end of the gas heat exchanger and is used to detect the gas pressure at the outlet end of the gas heat exchanger. A thermometer is installed at the outlet end of the gas heat exchanger to detect the gas temperature at the outlet end of the gas heat exchanger. A hot blast stove air-fuel ratio detector is installed on the hot blast stove to detect the air flow rate and gas flow rate in the hot blast stove; A thermocouple for the hot blast stove arch is installed at the arch of the hot blast stove and is used to detect the temperature of the hot blast stove arch. The gas pipeline bypass is also equipped with a gas heat exchanger inlet valve and a gas heat exchanger outlet valve; the gas heat exchanger inlet valve is located at the input end of the gas pipeline bypass and is used to control the gas entering the gas pipeline bypass; the gas heat exchanger outlet valve is located at the output end of the gas pipeline bypass and is used to control the preheated gas entering the hot blast stove. The main gas pipeline is also equipped with a gas shut-off valve, a gas regulating valve, and a main gas line valve. The gas shut-off valve is located at the connection between the main gas pipeline and the external gas pipeline network, and is used to shut off the connection between the main gas pipeline and the external gas pipeline network. The gas regulating valve is located between the gas shut-off valve and the node where the gas pipeline bypass connects to the main gas pipeline, and is used to regulate the gas flow rate. The main gas line valve is located at the connection between the main gas pipeline and the hot blast stove, and is used to control the gas from the main gas pipeline to enter the hot blast stove. The hot air furnace system also includes a flue gas purging module, located on the side of the flue gas near the hot air furnace, used to drive away and dilute the CO remaining in the flue gas.

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