Industrial furnace gas preheater fault handling system and control method thereof

Abstract

The application discloses an industrial furnace coal gas preheater fault processing system, a flue of an industrial furnace is connected with a hearth at one end and a chimney at the other end, a coal gas preheater is installed in the flue, temperature measuring points are arranged in front of and behind the coal gas preheater in the flue, and temperature measuring equipment is arranged in the front temperature measuring point and the rear temperature measuring point. When the coal gas preheater leaks and ignites, the application can timely send an early warning, automatically extinguish the fire, protect with nitrogen, control the temperature in front of the flue preheater below the coal gas ignition point, continue to maintain production, win time for production plan adjustment, and can plan to shut down and overhaul and process. The technology can directly stop the furnace program operation after extinguishing the fire, is safer and more effective than the previous operation of replacing the fire with nitrogen, and reduces labor intensity.

Description

TECHNICAL FIELD

[0001] The present application relates to the safety technical field of coal gas preheater. BACKGROUND

[0002] In the conventional combustion design of industrial furnace, a coal gas preheater is often arranged in the flue to save energy consumption. In use, the coal gas preheater may appear corrosion leakage phenomenon. When the flue temperature reaches the coal gas ignition temperature and the three ignition conditions are met, the preheater ignition accident may occur. If not extinguished in time, the steel structure of the preheater will lose stiffness and collapse, and the accident will expand. Unplanned emergency shutdown makes the production plan adjustment passive, affecting the yield and delivery period.

[0003] After the coal gas preheater ignites, the gas source is usually cut off to extinguish the fire. This operation requires the cooperation of multiple people, and nitrogen is introduced into the gas pipe network while gradually closing the gas main valve. The operation process needs to pay attention to the gas pipe network pressure at all times. If the cooperation is not proper, backfire accident may easily occur. If the pipe network flow is too fast, blowout phenomenon may also easily occur, resulting in a large amount of coal gas gathering in the flue and mixing with air, which is extremely easy to cause explosion accident. SUMMARY

[0004] The technical problem to be solved by the present application is to realize a safe and reliable application in a coal gas preheater, an ignition monitoring and automatic extinguishing system.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: an industrial furnace coal gas preheater fault handling system, one end of the flue of the industrial furnace is connected with the hearth, the other end is connected with the chimney, the coal gas preheater is installed in the flue, the front and rear of the coal gas preheater in the flue are provided with temperature measuring points, and the front temperature measuring point and the rear temperature measuring point are both provided with temperature measuring equipment.

[0006] The front part of the coal gas preheater is provided with a nitrogen inlet, the outer end of the nitrogen inlet is connected with a nitrogen source through a pipeline, and the nitrogen inlet is provided with an air inlet adjusting valve.

[0007] A gate valve is arranged in the flue between the coal gas preheater and the chimney.

[0008] The system is provided with a PLC, the PLC is connected with and outputs control signals to the gate valve and the air inlet adjusting valve, a pressure sensor is arranged in the hearth, and the temperature measuring equipment and the pressure sensor are both connected with and output sensing signals to the PLC.

[0009] The coal gas preheater is provided with two groups, the two groups of coal gas preheaters are separated by a heat preservation brick type fireproof wall, and the front and rear of the two groups of coal gas preheaters are both provided with independent temperature measuring points.

[0010] The communication port of the PLC is connected with external equipment, and the external equipment includes an alarm device, a server, a storage device and a mobile device.

[0011] The control method based on the industrial furnace gas preheater fault processing system acquires the temperature of the temperature measuring point in real time, and when the temperatures of the front and rear temperature measuring points are higher than the lower limit temperature set value and the temperature difference is greater than the temperature difference set value, the PLC performs an alarm and executes a fire extinguishing operation.

[0012] The fire extinguishing operation is that the air inlet regulating valve is opened to inject nitrogen into the flue, and the gate valve is closed; the alarm is that the time is abnormal or an alarm signal is sent to the external device.

[0013] When the fire extinguishing operation is executed, the temperature of the temperature measuring point is acquired in real time, and when the collected temperature drops to a preset safety temperature value, the air inlet regulating valve is closed, and the linkage relationship between the gate valve and the pressure in the hearth is restored.

[0014] When the front and rear temperature measuring points are compared, the two temperature measuring points are two temperature measuring devices on the same side of the heat preservation brick fire wall; the temperature difference set value is 100 degrees Celsius, and the lower limit temperature set value is 400-500 degrees Celsius.

[0015] The present application can timely send a pre-warning when the gas preheater leaks and ignites, and automatically extinguish the fire and protect with nitrogen, while controlling the temperature before the flue preheater to be below the gas ignition point, so that the production can be continued, time for production plan adjustment is won, and the furnace can be stopped for maintenance and processing in a planned manner. The technology can directly stop the furnace program operation after extinguishing the fire, is safer and more effective than the previous operation of replacing the fire with nitrogen, and reduces the labor intensity. BRIEF DESCRIPTION OF DRAWINGS

[0016] The content expressed by each figure in the specification of the present application and the marks in the figures are briefly described as follows:

[0017] Figure 1 It is a principle diagram of the industrial furnace gas preheater fault processing system;

[0018] The marks in the above figures are as follows: 1, flue; 2, gas preheater; 3, temperature measuring point; 4, heat preservation brick fire wall; 5, gate valve; 6, chimney; 7, nitrogen input port; 8, pressure sensor; 9, PLC. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application are further described in detail below by comparing the figures and through the description of the embodiments, the shape, structure, mutual position and connection relationship between the parts, the action and working principle of each part, the manufacturing process and operation and use method, etc. of the components involved are described in further detail, to help the skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present application.

[0020] As Figure 1As shown, the flue 1 of the industrial furnace is connected to the hearth at one end and to the chimney 6 at the other end, and the gas preheater 2 is installed in the flue 1. When the gas preheater 2 is large or more, it can be divided into two groups, and a heat preservation brick type fire wall 4 is arranged between adjacent preheaters. The front and rear of the two groups of gas preheaters 2 are provided with independent temperature measuring points 3. The heat preservation brick type fire wall 4 is arranged along the direction of the flue gas flow, and cannot affect the normal flow of the flue gas in the flue 1. It is only a spacing effect. The heat preservation brick type fire wall 4 makes the temperature measurement between adjacent preheaters not interfere with each other, and ensures that there is a significant difference in the temperature detected between adjacent preheaters when a fire occurs at a certain place.

[0021] The front and rear of the gas preheater 2 in the flue 1 are provided with temperature measuring points 3. The front temperature measuring point 3 and the rear temperature measuring point 3 are provided with temperature measuring equipment. The direction of the gas preheater 2 close to the hearth is the front, and the direction close to the chimney 6 is the rear. For the layout with the heat preservation brick type fire wall 4, two plug-in type temperature measuring devices are arranged in groups behind the gas preheater 2, and two plug-in type temperature measuring devices are also arranged in groups in front of the preheater.

[0022] In order to be able to automatically extinguish the fire when the fire occurs, the front of the gas preheater 2 is provided with a nitrogen inlet 7. The outer end of the nitrogen inlet 7 is connected to a nitrogen source through a pipeline. The nitrogen inlet 7 is provided with an inlet regulating valve. In addition, a gate valve 5 is arranged in the flue 1 between the gas preheater 2 and the chimney 6, and a pressure sensor 8 is arranged in the hearth. The entire system is controlled by a PLC 9. The gate valve 5 of the flue 1 and the nitrogen inlet valve are electrically controlled valves, and are connected to the PLC 9 for interlocking control. The PLC 9 is connected to and outputs control signals to the gate valve 5, the inlet regulating valve, the temperature measuring equipment and the pressure sensor 8, and outputs sensing signals to the PLC 9. The PLC 9 realizes automatic monitoring and control. External devices can be connected to the communication port of the PLC 9. The external devices include alarm devices, servers, storage devices and mobile devices. The external devices can be used for alarm, recording and other work, which is convenient for the staff to maintain in time.

[0023] The above gate valve is used to adjust the pressure of the hearth, control the flue gas flow rate and smoke temperature of the flue 1. The PLC 9 obtains the pressure in the hearth, and controls the opening degree of the gate valve of the flue 1 through linkage, so as to realize the interlocking of the hearth pressure and control the hearth pressure.

[0024] When the temperature of the plug-in type temperature measuring point 3 behind the gas preheater 2 suddenly rises obviously and far exceeds the normal working temperature (for example, the temperature process of the gas preheater 2 is generally controlled at about 300°C, the temperature will gather and rise after the fire, and will continue to rise over time within a period of time, and will be close to or higher than the temperature measured in front of the preheater on the other side of the heat preservation brick type fire wall 4, and the difference between the adjacent temperatures behind the preheater is also obvious), it can be judged that the preheater is on fire.

[0025] The working principle of the system is to block any one of the three conditions of "oxygen, combustible material and ignition temperature" in the fire triangle through technical measures, so as to extinguish the fire. After the fire is extinguished, production can be temporarily resumed. By blocking the formation of oxygen and ignition temperature, the formation of the three elements of combustion is avoided, so as to prevent the re-ignition and combustion of leaked coal gas. After the production plan is adjusted, the plan is stopped for maintenance;

[0026] Based on the control method of the upper industrial furnace coal gas preheater 2 fault handling system, the temperature of the temperature measuring point 3 is acquired in real time. When the temperature of the temperature measuring point 3 inserted in the coal gas preheater 2 suddenly rises obviously and far exceeds the normal working temperature, that is, when the temperature of the front and rear temperature measuring points 3 is higher than the lower limit temperature setting value, and the temperature difference is greater than the temperature difference setting value, it can be judged that the preheater is on fire at this time. PLC 9 alarms and executes the fire extinguishing operation.

[0027] In the program setting, when the temperature difference between the adjacent temperature measuring points 3 before or after the preheater is ≥100℃, the PLC 9 judges that the preheater is on fire. At this time, the operation room HMI picture pops up a dialog box picture prompting the word "flue 1 on fire", and triggers the sound and light alarm device to give early warning;

[0028] The fire extinguishing operation is to open the inlet regulating valve step by step under the condition that the temperature difference between the adjacent temperature before or after the preheater is ≥100℃, and nitrogen is introduced into the flue 1. At this time, the flue 1 gate valve no longer acts as the condition of the furnace pressure setting value, but only gradually closes with the opening of the inlet regulating valve. At this time, the fire of the preheater is automatically extinguished because the flue 1 is under positive pressure and loses the oxygen combustion condition. The alarm is an abnormal time or alarm signal sent to external equipment, such as the operation room HMI picture popping up a dialog box picture prompting the word "flue 1 on fire", and triggering the sound and light alarm device to give early warning;

[0029] After the preheater leakage point is on fire and extinguished, the temperature of the temperature measuring point 3 on the fire side will decrease to the temperature of the adjacent temperature measuring point 3 of the preheater, and the adjacent temperature difference is within 100℃. At this time, the flue 1 gate valve 5 lacks the trigger condition of the adjacent temperature difference ≥100℃ on the same side of the preheater, and the flue 1 gate valve restores the interlock with the furnace pressure, and only controls the furnace pressure. At this time, the temperature setting value of the temperature measuring point 3 before the preheater is set to be much lower than the coal gas ignition temperature value (for example, the coke oven gas ignition temperature is about 600℃, and we can set the setting value to 400-500℃) in the operation interface, and the nitrogen inlet valve is interlocked and put into automatic control. When the temperature before the preheater approaches the setting value, the nitrogen inlet valve is gradually opened, nitrogen is sent into the flue 1 to cool the flue 1, so that the temperature before the preheater is always maintained within the safe setting value range below the coal gas ignition temperature, so as to prevent the formation of the "fire triangle" condition and avoid re-ignition.

[0030] The application is described above in conjunction with the drawings, and it is obvious that the specific implementation of the application is not limited by the above manner, as long as various non-essential improvements are made by using the method concept and technical solution of the application, or the concept and technical solution of the application is directly applied to other occasions without improvement, which are all within the protection scope of the application.

Claims

1. A system for handling a failure of an industrial furnace gas preheater, the industrial furnace having a flue connected at one end to a furnace chamber and at the other end to a chimney, the gas preheater being installed in the flue, characterized in that: The flue gas preheater is provided with temperature measuring points in front and behind thereof, and the front and rear temperature measuring points; Real-time temperature of the temperature measuring points is acquired, and when the temperature of the front and rear temperature measuring points is higher than the lower limit temperature setting value and the temperature difference is greater than the temperature difference setting value, the PLC alarms and executes the fire extinguishing operation; After the fire of the leakage point of the preheater is extinguished, the temperature of the temperature measuring point on the fire side decreases to within 100°C of the temperature difference of the temperature measuring point adjacent to the preheater, the flue damper valve is triggered due to the lack of the adjacent temperature difference of the preheater on the same side being greater than 100°C, and the flue damper is restored to be interlocked with the furnace pressure for controlling the furnace pressure. The coal gas preheater is provided with two groups, the two groups of coal gas preheaters are separated by a heat preservation brick type fire wall, and the front and rear of the two groups of coal gas preheaters are provided with independent temperature measuring points. When the front and rear temperature measuring points are compared, the two temperature measuring points are two temperature measuring devices on the same side of the heat preservation brick type fire wall, the temperature difference setting value is 100°C, and the lower limit temperature setting value is 400-500°C.

2. The industrial furnace gas preheater fault handling system of claim 1, wherein: The front part of the coal gas preheater is provided with a nitrogen inlet, the outer end of the nitrogen inlet is connected with a nitrogen source through a pipeline, and the nitrogen inlet is provided with an inlet regulating valve.

3. The industrial furnace gas preheater fault handling system of claim 2, wherein: A damper valve is arranged in the flue between the coal gas preheater and the chimney.

4. The industrial furnace gas preheater fault handling system of claim 3, wherein: The system is provided with a PLC, the PLC is connected with and outputs control signals to the damper valve and the inlet regulating valve, the furnace is provided with a pressure sensor, and the temperature measuring device and the pressure sensor are connected with and output sensing signals to the PLC.

5. The industrial furnace gas preheater fault handling system of claim 4, wherein: The communication port of the PLC is connected with external devices, and the external devices include an alarm device, a server, a storage device and a mobile device.

6. The industrial furnace gas preheater fault handling system of claim 5, wherein: The fire extinguishing operation is that the inlet regulating valve is opened to inject nitrogen into the flue, and the damper valve is closed; and the alarm is that an abnormal time or an alarm signal is sent to the external device.

7. The industrial furnace gas preheater fault handling system of claim 6, wherein: When the fire extinguishing operation is executed, the temperature of the temperature measuring point is acquired in real time, and when the acquired temperature decreases to a preset safety temperature value, the inlet regulating valve is closed, and the damper valve is restored to be interlocked with the pressure in the furnace.

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