Safe and rapid furnace starting method for heat treatment furnace

Abstract

The invention relates to the technical field of heat treatment furnace starting, in particular to a safe and rapid furnace starting method for a heat treatment furnace, and before furnace starting, process, mechanical and electrical overhaul, confirmation of personnel protection, public medium pressure, fan operation, normal safety monitoring equipment and in-place valve state need to be completed. During ignition, gas pipeline preparation, nitrogen purging, gas supply replacement, CO detection and burner ignition are sequentially carried out, pressure, flame and interlocking states are monitored in the whole process, no leakage and no detonation are ensured, parameters are continuously checked after the furnace is started, and abnormity is recorded. The invention solves the problems that the furnace temperature of a heat treatment furnace is frequently switched due to multiple types of steel produced by the existing heat treatment production line, impure product specifications and different heat treatment systems required by the process of different types of steel, and the sudden part fault of the heat treatment furnace possibly requires sudden shutdown for maintenance; at present, a safe and rapid furnace starting method for frequently starting and stopping the heat treatment furnace does not exist.

Description

Technical Field

[0001] The present invention relates to the technical field of starting up a heat treatment furnace, and specifically refers to a method for safely and quickly starting up a heat treatment furnace. Background Art

[0002] At present, there is no explosion-proof warning system for heat treatment furnaces, and it is impossible to prevent in advance when burners or other auxiliary equipment fail, posing a greater potential safety hazard. Improving the mechanical properties of plain steel through heat treatment is the most direct way to achieve lightweight and thus energy conservation and emission reduction. The roller hearth open-flame heat treatment furnace is a key equipment on the steel plate heat treatment production line, with a high degree of automation and is widely favored by major steel enterprises.

[0003] At present, there are many steel grades produced on the heat treatment production line, and the product specifications are miscellaneous. The heat treatment systems required by different steel grades have differences in process requirements, resulting in frequent switching of the furnace temperature of the heat treatment furnace. Sudden component failures of the heat treatment furnace itself may also require sudden shutdown for maintenance. Currently, there is no safe and quick method for starting up the heat treatment furnace frequently. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that there are many steel grades produced on the existing heat treatment production line, the product specifications are miscellaneous, the heat treatment systems required by different steel grades have differences in process requirements, resulting in frequent switching of the furnace temperature of the heat treatment furnace. Sudden component failures of the heat treatment furnace itself may also require sudden shutdown for maintenance. Currently, there is no safe and quick method for starting up the heat treatment furnace frequently.

[0005] To solve the above problems, the technical solution adopted by the present invention is a method for safely and quickly starting up a heat treatment furnace. The safe and quick start-up includes the following steps:

[0006] S1: All process-related items have been repaired.

[0007] S2: All mechanical-related items have been repaired.

[0008] S3: All electrical-related items have been repaired.

[0009] S4: All on-site construction personnel have evacuated the construction personnel have left the site.

[0010] S5: All personnel participating in ignition wear gas alarms, and ensure that one set of air respirators on site is available.

[0011] S6: Confirm that the net cycle water and compressed air pressures of the heat treatment are normal. The net cycle water pressure > 0.2 MPa, and the compressed air > 0.4 Mpa. The net cycle water pressure is the net cycle water pressure required for the normal operation of the heat treatment furnace, and the compressed air pressure is the compressed air pressure required for the normal operation of the heat treatment furnace.

[0012] S7: The combustion-supporting fan starts and operates automatically for more than 30 minutes. The gas-discharge valve is opened to 100% (after normal temperature rise, the gas-discharge operates automatically), and the combustion-supporting fan is within the normal range.

[0013] S8: After the exhaust fan starts, it operates automatically for more than 30 minutes, and the pressure of the exhaust fan is within the normal range.

[0014] S9: Confirm that the CO detector in the exhaust pipe operates normally, and the CO detector is normally powered on and running.

[0015] S10: The quick-cutoff valve and regulating valve of the gas are tested and operate normally. The furnace shutdown interlock and voice control alarm are debugged normally, and they can be opened and closed normally without jamming. The pressures of the compressed air, combustion-supporting, and exhaust pipes are normal.

[0016] S11: Confirm that all the gas manual valves of the burners in the heat treatment furnace are in the closed state, and the furnace door is in the open position. The valves can be opened and closed normally to the position, and the furnace door can be opened and closed normally without jamming, then the subsequent ignition work can be carried out.

[0017] Furthermore, the confirmation process of the ignition of the heat treatment furnace in step S11 includes the following steps:

[0018] 1) Open the gas-discharge valve of the gas branch pipe. Confirm that the sampling valve is in the closed state, and confirm that both the blind plate valve and butterfly valve of the gas main pipe are in the closed state. The valves can be opened and closed normally to the position, and there is no obvious leakage in the blind plate valve and butterfly valve.

[0019] 2) Open the quick-cutoff valve of the gas and the regulating valve of the gas main pipe. Connect the nitrogen purge hose for the gas pipeline and conduct nitrogen purging. After the nitrogen purging is completed, close the nitrogen valve and remove the nitrogen pipe. The nitrogen valve first closes the valve at the far end of the blind plate valve, then closes the proximal valve, and finally removes the nitrogen hose. The purging nitrogen pressure is within 5 - 12 kPa, purging for more than 15 minutes, the oxygen content at the sampling port is < 0.5%, and the nitrogen pressure is the normal operating pressure of this heat treatment furnace.

[0020] 3) First open the blind plate valve, then open the butterfly valve to supply gas, and activate the "furnace shutdown interlock". The pressure of the gas main pipe is 10 - 15 kPa, and there is no leakage in the valves. The pressure of the gas main pipe is the normal operating pressure of this heat treatment furnace.

[0021] 4) Conduct gas replacement for 15 - 20 minutes. After the explosion test is qualified, close the gas-discharge valve of the branch pipe and the sampling valve. There is no explosion sound, and it continues to burn to the bottom of the cylinder, and it is qualified continuously for 3 times.

[0022] 5) The CO concentration at the furnace door for loading and unloading is lower than 24 ppm, and the CO content is lower than 24 ppm.

[0023] 6) Ignite the burners at the site of the heat treatment furnace. The gas manual valve of the faulty burner must be closed and recorded, and the interlock conditions are normally activated.

[0024] The advantages of the present invention compared with the prior art are as follows:

[0025] (1) Safety improvement: All personnel involved in ignition wear gas alarms, and ensure that there are available air respirators on site, increasing the safety guarantee for personnel during operation; strict procedures for purging and replacing the gas pipeline ensure that the oxygen content in the gas is lower than the safety standard, reducing the risk of gas explosion; continuously monitoring the CO concentration to ensure that the CO concentration at the furnace door for charging and discharging is lower than the safety value, protecting the health of on-site personnel.

[0026] (2) Operation standardization: Detailed preparation steps before starting the furnace, including maintenance of process, machinery, and electrical items, as well as evacuation of on-site personnel, ensure the standardization and orderliness of the furnace start-up operation; clear steps in the ignition process, including preparation, purging, replacement, ignition, etc. of the gas pipeline, with specific operation requirements and confirmation criteria for each step, reducing the possibility of operation errors.

[0027] (3) Efficiency improvement: By reasonably starting and commissioning the fan, and the purging and replacement process of the gas pipeline, the furnace start-up time is shortened and the start-up efficiency is improved; strict confirmation of valve status and input of interlock conditions ensure the coordinated operation of each device during the furnace start-up process, reducing the start-up delay caused by equipment failures.

[0028] (4) Equipment protection: Confirm the pressure of public media (such as clean circulating water, compressed air) before starting the furnace to ensure the pressure supply of the equipment within the normal operating range, reducing equipment damage caused by abnormal pressure; continuously monitor the operating status and parameters of the equipment, promptly discover and handle abnormal situations, and protect the long-term stable operation of the equipment. Description of the Drawings

[0029] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0030] Figure 1 It is the working flow chart in a method for safely and quickly starting up a heat treatment furnace according to the present invention. Detailed Embodiments

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] The present invention provides a technical solution: to solve the existing problems raised in the background art.

[0033] The safe and rapid start-up of the present invention for the furnace includes the following steps:

[0034] S1: After the overhaul of process-related items; conduct a comprehensive inspection and calibration of the process parameters of the heat treatment furnace, including but not limited to the comparison between the set values and the actual measured values of key process parameters such as furnace temperature control accuracy, heating rate, holding time, cooling rate, etc., to ensure that the error is within the allowable range; check the process pipeline system of the heat treatment furnace, including gas pipelines, natural gas pipelines, cooling water pipelines, compressed air pipelines, etc., confirm that the pipelines are free of leaks and blockages, the connection parts are well sealed, and the pipeline supports are stable; check the furnace lining inside the heat treatment furnace to see if there are cracks, spalling, wear, etc. If there is damage, it should be repaired or replaced in time to ensure the heat insulation performance and structural integrity of the furnace lining; check the heating elements of the heat treatment furnace, such as resistance wires, electric heating tubes, etc., confirm that there is no short circuit or open circuit phenomenon, and the arrangement and connection of the heating elements meet the design requirements; conduct a comprehensive test on the process automation control system of the heat treatment furnace, including temperature control module, pressure control module, flow control module, etc., to ensure that the system can accurately collect and process data, and realize the automatic adjustment and stable control of process parameters.

[0035] S2: After the overhaul of mechanical-related items; conduct a comprehensive inspection and maintenance of the mechanical transmission components of the heat treatment furnace, such as the furnace door lifting mechanism, the in-furnace workpiece conveying mechanism, the fan drive mechanism, etc., check whether the gears, chains, belts, etc. of the transmission components are worn or loose, and adjust or replace them if necessary; check the furnace body structure of the heat treatment furnace, including the furnace shell, furnace door, observation window, etc., confirm that the furnace body is free of deformation and cracks, the furnace door is well sealed, and the observation window glass is not damaged; check the support structure and foundation of the heat treatment furnace to ensure that the support structure is stable, the foundation has no settlement and cracks, and ensure the stability and safety of the heat treatment furnace during operation; check the tooling fixtures inside the heat treatment furnace to confirm that they are firmly installed and accurately positioned, and can meet the heat treatment requirements of the workpieces; conduct a comprehensive inspection and test on the mechanical safety devices of the heat treatment furnace, such as limit switches, safety valves, emergency stop buttons, etc., to ensure that the safety devices are sensitive and reliable and can play a role in a timely manner in case of emergency.

[0036] S3: The electrical-related projects have been repaired; conduct a comprehensive inspection of the electrical control system of the heat treatment furnace, including the power cabinet, control cabinet, operation console, etc., check whether the electrical components are firmly installed, whether the wiring is correct and firm, without looseness or short-circuit; check the electrical protection devices of the heat treatment furnace, such as circuit breakers, fuses, leakage protectors, etc., confirm that their specifications and performances meet the requirements and can play the protection role normally; conduct a comprehensive inspection and maintenance of the motors of the heat treatment furnace, including measuring the insulation resistance of the motors, checking the bearing lubrication conditions, monitoring the running sound and vibration of the motors, etc., to ensure the normal operation of the motors; check the lighting system and signal system of the heat treatment furnace, confirm that the lighting lamps have sufficient brightness and no damage, and the signal indicators display accurately and clearly; conduct a comprehensive inspection of the grounding system of the heat treatment furnace, measure the grounding resistance value, ensure that the grounding resistance meets the safety requirements, and guarantee the safety of the equipment and personnel.

[0037] S4: All on-site construction personnel have been evacuated; the construction personnel have evacuated the site; the personnel participating in ignition are all wearing gas alarms, and ensure that one set of air respirators on-site is available; before starting the furnace, conduct a comprehensive inspection of the construction site of the heat treatment furnace to ensure that all construction personnel have been safely evacuated and there are no unrelated personnel staying on-site; equip the personnel participating in ignition with gas alarms that meet national standards and industry requirements, and ensure that the alarms have good performance and sufficient power and can accurately detect the gas concentration; equip one set of air respirators with good performance and passing inspection on-site, place them in an easily accessible position, and ensure that the ignition personnel can use them quickly in case of emergency.

[0038] S5: Confirm that the pressure of the net cycle water and compressed air for heat treatment is normal; the pressure of the net cycle water > 0.2 MPa, and the compressed air > 0.4 MPa;

[0039] S6: The combustion-supporting fan is started and put into automatic operation for more than 30 minutes, and the relief valve is opened to 100% (after normal temperature rise, the relief valve is put into automatic operation); the combustion-supporting fan is within the normal range;

[0040] S7: After the exhaust fan is started, it is put into automatic operation for more than 30 minutes; the pressure of the exhaust fan is within the normal range;

[0041] S8: Confirm that the CO detector in the exhaust pipe operates normally; the CO detector is turned on and operates normally;

[0042] S9: The quick-cut valve and regulating valve of the gas are tested to operate normally, and the furnace shutdown interlock and voice control alarm are debugged normally; they can be opened and closed normally without jamming, and the pressure of the compressed air, combustion-supporting and exhaust pipes is normal;

[0043] S10: Confirm that all the gas manual valves of the burners of the heat treatment furnace are in the closed state, and the furnace door is in the open position; the valves can be opened and closed normally in place, and the furnace door can be opened and closed normally without jamming, then the subsequent ignition work can be carried out.

[0044] The confirmation of the ignition process of the heat treatment furnace includes the following steps:

[0045] 1) Open the gas branch pipe's relief valve, confirm that the sampling valve is in the closed state, and confirm that the main gas pipe's blind valve and butterfly valve are both in the closed state. The valves can be normally opened and closed in place, and there is no obvious leakage in the blind valve and butterfly valve;

[0046] 2) Open the gas quick cut-off valve and the main gas pipe regulating valve, connect the hose for nitrogen purging of the gas pipeline, conduct nitrogen purging. After the nitrogen purging is completed, close the nitrogen valve and remove the nitrogen pipe. The nitrogen valve closes the valve at the far end of the blind valve first, then closes the proximal valve, and finally removes the nitrogen hose. The purging nitrogen pressure is within 5 - 12 kPa, purging for more than 15 minutes, and the oxygen content at the sampling port is < 0.5%;

[0047] 3) First open the blind valve, then open the butterfly valve to supply gas, and put into the "furnace shutdown interlock". The main gas pipe pressure is 10 - 15 kPa, and there is no leakage in the valves;

[0048] 4) Conduct gas replacement for 15 - 20 minutes. After the explosion test is qualified, close the branch pipe relief valve and the sampling valve. There is no explosion sound, and it burns continuously to the bottom of the cylinder, and it is qualified for 3 consecutive times;

[0049] 5) The CO concentration at the charging and discharging furnace door is lower than 24 ppm, and the CO content is lower than 24 ppm;

[0050] 6) Ignite the burners of the heat treatment furnace on-site. The gas manual valve of the faulty burner must be closed and recorded, and the interlock conditions are normally put into operation. The working process of this application is as follows:

[0051] First, complete the maintenance of the process, machinery, and electrical related items and ensure that all on-site construction personnel have withdrawn. The personnel participating in the ignition wear gas alarms and are equipped with air respirators. Then confirm that the heat treatment net cycle water pressure is greater than 0.2 MPa, the compressed air pressure is greater than 0.4 MPa, start the combustion-supporting fan and put it into automatic operation for more than 30 minutes with the relief valve fully open, and at the same time start the exhaust fan and put it into automatic operation for more than 30 minutes. Subsequently, confirm that the CO detector in the exhaust pipe operates normally, the gas quick cut-off valve and the regulating valve are tested to operate normally, and the furnace shutdown interlock and the voice control alarm are debugged normally. Confirm that all the gas manual valves of the heat treatment furnace burners are closed and the furnace door is open. During the ignition process, first open the gas branch pipe relief valve and close the sampling valve, confirm that the main gas pipe blind valve and butterfly valve are closed, then conduct nitrogen purging. After the purging is completed, close the nitrogen valve and remove the nitrogen pipe. Then open the blind valve and butterfly valve to supply gas and put into the furnace shutdown interlock. After 15 to 20 minutes of gas replacement, conduct an explosion test. After passing the test, close the branch pipe relief valve and the sampling valve. Finally, confirm that the CO concentration at the charging and discharging furnace door is lower than 24 ppm, conduct on-site ignition of the heat treatment furnace burners, the gas manual valve of the faulty burner must be closed and recorded, and at the same time ensure that the interlock conditions are normally put into operation.

[0052] The above describes the present invention and its embodiments. Such description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. In general, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar structural modes and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A method for safely and quickly starting a heat treatment furnace, characterized in that: Safe and rapid furnace startup includes the following steps: S1: Maintenance of process-related items is completed; S2: Maintenance of mechanical-related items is completed; S3: Maintenance of electrical-related items is completed; S4: All on-site construction personnel have withdrawn from the site; personnel involved in ignition are all wearing gas alarms, and ensure that one set of air respirators on-site is available; S5: Confirm that the net cycle water and compressed air pressures for heat treatment are normal (net cycle water pressure > 0.2 MPa, compressed air > 0.4 MPa); the net cycle water pressure is the net cycle water pressure required for the normal operation of the heat treatment furnace, and the compressed air pressure is the compressed air pressure required for the normal operation of the heat treatment furnace; S6: The combustion-supporting fan is started and put into automatic operation for more than 30 minutes, and the relief valve is opened to 100% (after normal temperature rise, the relief valve is put into automatic operation); the combustion-supporting fan is within the normal range; S7: After the exhaust fan is started, it is put into automatic operation for more than 30 minutes; the exhaust fan pressure is within the normal range; S8: Confirm that the CO detector in the exhaust pipe operates normally; the CO detector is normally powered on and running; S9: The gas quick cut-off valve and regulating valve are tested for normal operation, the furnace shutdown interlock and voice control alarm are debugged normally, they can be opened and closed normally, without jamming, and the pressures of compressed air, combustion-supporting and exhaust pipes are normal; S10: Confirm that all gas manual valves of the burners of the heat treatment furnace are in the closed state, and the furnace door is in the open position. The valves can be normally opened and closed in place, and the furnace door can be normally opened and closed without jamming, then the subsequent ignition work can be carried out.

2. The method for safely and quickly starting a heat treatment furnace according to claim 1, characterized in that: In the S11 step, the confirmation of the ignition process of the heat treatment furnace includes the following steps: 1) Open the relief valve of the gas branch pipe, confirm that the sampling valve is in the closed state, and confirm that both the main gas pipe blind valve and butterfly valve are in the closed state. The valves can be normally opened and closed in place, and there is no obvious leakage in the blind valve and butterfly valve; 2) Open the gas quick cut-off valve and the regulating valve of the main gas pipe, connect the nitrogen purge hose for the gas pipeline, conduct nitrogen purging. After the nitrogen purging is completed, close the nitrogen valve and remove the nitrogen pipe. The nitrogen valve first closes the remote valve of the blind valve, then closes the proximal valve, and finally removes the nitrogen hose. The purging nitrogen pressure is within 5 - 12 kPa, purging for more than 15 minutes, the oxygen content at the sampling port < 0.5%, and the nitrogen pressure is the normal operating pressure of this heat treatment furnace; 3) First open the blind valve, then open the butterfly valve to supply gas, and put into the "furnace shutdown interlock". The main gas pipe pressure is 10 - 15 kPa, and there is no leakage in the valve. The pressure of the main gas pipe is the normal operating pressure of this heat treatment furnace; 4) Conduct gas replacement for 15 - 20 minutes. After the explosion test is qualified, close the relief valve of the branch pipe and the sampling valve. There is no explosion sound, and it continues to burn to the bottom of the cylinder, and it is qualified continuously for 3 times; 5) The CO concentration at the furnace door for loading and unloading is lower than 24 ppm, and the CO content is below 24 ppm; 6) Ignite the burners of the heat treatment furnace on-site. The gas manual valves of faulty burners must be closed and recorded, and the interlock conditions are normally put into operation.

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