Combustion-supporting air system of heat treatment furnace and control method of combustion-supporting air system

Abstract

The invention relates to a combustion-supporting air system of a heat treatment furnace and a control method of the combustion-supporting air system, and the system comprises the heat treatment furnace, a circulating fan, a natural gas pipe, a smoke exhaust air pipe, a combustion-supporting air pipe, a smoke exhaust fan, a combustion-supporting fan and a heat exchanger, the end, away from the combustion-supporting air pipe, of the cooling air pipe extends into the circulating fan to cool a main shaft bearing of the circulating fan. When the combustion-supporting air control system of the heat treatment furnace works, airflow in the combustion-supporting air pipe can be introduced into the circulating fan through the cooling air pipe to blow the main shaft bearing of the circulating fan, air cooling is conducted on the main shaft bearing of the circulating fan, and the situation that the temperature of the main shaft bearing of the circulating fan is too high, and consequently lubricating oil on the main shaft bearing goes bad is avoided; workers do not need to frequently replace lubricating oil on the main shaft bearing, the labor intensity of the workers is reduced, and waste of the lubricating oil can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion-supporting air control of a heat treatment furnace, and more specifically, to a combustion-supporting air system of a heat treatment furnace and a control method thereof. Background Art

[0002] The purpose of the circulating fan is to make the temperature field and atmosphere uniformity in the furnace consistent through the strong stirring of the fan, so as to ensure that the products in the furnace are heated evenly. Most of the existing heat treatment furnaces use embedded circulating fans. The embedded circulating fans have compact structure and small size, which can effectively save space and can also be directly extended into the inner cavity of the heat treatment furnace. The working efficiency of the circulating fans is higher. Therefore, most of the existing heat treatment furnaces use embedded circulating fans.

[0003] During the operation of the heat treatment furnace, the circulating fan needs to operate uninterruptedly. As the circulating fan continues to operate, the temperature of the main shaft of the circulating fan will increase. In addition, when the heat treatment furnace is working, the heat in the furnace will also radiate outward, which will further increase the temperature of the main shaft of the circulating fan. When the main shaft of the circulating fan is in a high temperature state for a long time, the lubricating oil of the main shaft will deteriorate. The deteriorated lubricating oil cannot play the role of lubricating the bearings. If the bearing uses the deteriorated lubricating oil for a long time, it will cause the bearing to be damaged. In order to avoid damage to the main shaft caused by deteriorated lubricating oil, the staff needs to frequently replace the lubricating oil, which is not only time-consuming and labor-intensive, but also causes additional waste of lubricating oil. Summary of the invention

[0004] In order to overcome the problem in the above-mentioned prior art that the bearing lubricating oil of the circulating fan is easily deteriorated when the heat treatment furnace works for a long time, the present invention provides a combustion-supporting air system for a heat treatment furnace and a control method thereof. The combustion-supporting air control system for the heat treatment furnace in this scheme can accelerate the heat dissipation of the circulating fan bearings and avoid the deterioration of the bearing lubricating oil of the circulating fan due to high temperature.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a combustion-supporting air system for a heat treatment furnace, comprising a heat treatment furnace, a circulating fan embedded in the heat treatment furnace, a natural gas pipe connected to the inner cavity of the heat treatment furnace, a smoke exhaust duct and a combustion-supporting air duct, as well as a smoke exhaust fan connected to the air inlet end of the smoke exhaust duct, a combustion-supporting fan connected to the air inlet end of the combustion-supporting air duct, and a heat exchanger that completes heat exchange between the smoke exhaust duct and the combustion-supporting air duct, an end of the combustion-supporting air duct close to the combustion-supporting air duct is also connected to a cooling air duct, and an end of the cooling air duct away from the combustion-supporting air duct extends into the interior of the circulating fan to cool the main shaft bearing of the circulating fan.

[0006] When the heat treatment furnace is working, natural gas is transported to the inner cavity of the heat treatment furnace through the natural gas pipe, the combustion-supporting fan transports combustion-supporting air to the inner cavity of the heat treatment furnace through the combustion-supporting air duct, the circulating fan works to realize the gas circulation in the inner cavity of the heat treatment furnace, and then the smoke generated by the combustion in the heat treatment furnace is discharged through the smoke exhaust fan and the smoke exhaust air duct. The heat exchanger can transfer the smoke temperature in the smoke exhaust air duct to the combustion-supporting air in the combustion-supporting air duct, thereby increasing the temperature of the combustion-supporting air. At the same time, after the combustion-supporting fan starts working, a part of the combustion-supporting air in the combustion-supporting air duct will enter the cooling air duct and move along the cooling air duct until it is discharged from the cooling air duct, and the main shaft bearing of the circulating fan is purged. During the purging process, the heat on the surface of the main shaft bearing is taken away, and the air cooling of the main shaft bearing is completed.

[0007] When working, the combustion-supporting air control system of the heat treatment furnace in this scheme can introduce the airflow in the combustion-supporting air duct into the circulating fan through the cooling air duct to blow the main shaft bearings of the circulating fan, and cool the main shaft bearings of the circulating fan by air, so as to avoid the main shaft bearings of the circulating fan from being overheated and causing the lubricating oil on the main shaft bearings to deteriorate. The staff does not need to frequently replace the lubricating oil on the main shaft bearings, which reduces the labor intensity of the staff and avoids the waste of lubricating oil.

[0008] The setting of the heat exchanger can transfer the heat of the flue gas to be discharged in the smoke exhaust duct to the combustion-supporting air in the combustion-supporting air duct, thereby increasing the temperature of the combustion-supporting air and preventing the temperature of the heat treatment furnace cavity from becoming low after the combustion-supporting air enters the heat treatment furnace due to too low a temperature.

[0009] Preferably, the main shaft bearing of the circulating fan is sleeved with an air-cooling shell, and an annular air-cooling cavity is arranged in the air-cooling shell. The end of the air-cooling cavity close to the inner cavity of the heat treatment furnace is a closed end face, and the lubricating oil on the main shaft bearing is located between the air-cooling shell and the main shaft bearing, and the end of the cooling air duct connected to the air-cooling shell is located on the side of the outer surface of the air-cooling shell close to the closed end face. After the heat on the main shaft bearing is dissipated outward and transferred to the air-cooling shell, it can be carried away by the air flow in the air-cooling shell, so as to avoid the accumulation of heat and thus avoid the temperature of the main shaft bearing being too high. The setting of the air-cooling shell can prevent the cooling wind from blowing directly on the main shaft bearing and blowing away the lubricating oil on the main shaft bearing. The closed end face on the air-cooling shell is close to the inner cavity of the heat treatment furnace, so as to prevent the cooling wind from blowing into the heat treatment furnace along the circulating fan.

[0010] Preferably, a natural gas orifice flowmeter, a second ball valve, a gas solenoid valve in front of the mouth, a proportional valve and a linear valve are sequentially arranged on the natural gas pipe, wherein the linear valve is closest to the heat treatment furnace; a combustion air orifice flowmeter, an electric regulating valve, a third solenoid valve and an air manual butterfly valve are sequentially arranged on the combustion air duct between the heat treatment furnace and the heat exchanger, wherein the air manual butterfly valve is closest to the heat treatment furnace, and the gas solenoid valve in front of the mouth and the third solenoid valve are both fast-opening and fast-breaking solenoid valves. When the heat treatment furnace is working, the ratio of natural gas and combustion air entering the inner cavity of the heat treatment furnace is obtained through the natural gas orifice flowmeter and the combustion air orifice flowmeter. When the ratio of natural gas and combustion air is out of balance, the opening of the natural gas pipe is adjusted through the proportional valve and the linear valve, and the opening of the combustion air duct is adjusted through the electric regulating valve, so as to achieve the purpose of adjusting the flow of natural gas and combustion air, and then adjust the ratio of natural gas and combustion air, so as to achieve the precise ratio of natural gas and combustion air, so that the heat treatment furnace can be fully burned, and the purpose of energy saving and consumption reduction is achieved. The gas solenoid valve in front of the burner and the third solenoid valve are both fast-opening and fast-breaking solenoid valves. When the temperature in the heat treatment furnace reaches the process temperature, the gas solenoid valve in front of the burner quickly acts to cut off the gas supply. After the burner is extinguished, the combustion-supporting air continues to blow for 3-5s, and then the third solenoid valve quickly acts to cut off the combustion-supporting air supply to prevent the combustion-supporting air from continuously entering the furnace and causing the temperature in the furnace to drop rapidly.

[0011] Preferably, the natural gas pipe is also provided with a first ball valve, a first solenoid valve and an electromagnetic relief valve, and the first ball valve, the first solenoid valve, the electromagnetic relief valve, the natural gas orifice flow meter, the second ball valve, the front-mouth gas solenoid valve, the proportional valve and the linear valve are sequentially arranged on the natural gas pipe. The ball valve and the solenoid valve can control the opening and closing of the natural gas pipe to prevent the natural gas pipe from being unable to open and close normally due to damage to a certain valve. The electromagnetic relief valve can release pressure and deflate gas when the pressure in the pipe is too high to prevent the excessive pressure in the pipe from causing an explosion during the transportation of natural gas.

[0012] Preferably, the proportional valve is also connected to a collection pipe, the other end of which is connected to the combustion-supporting air pipe, and one end of the collection pipe connected to the combustion-supporting air pipe is located between the third solenoid valve and the manual air butterfly valve. After the collection pipe is connected to the proportional valve, it can monitor whether the third solenoid valve is completely closed.

[0013] Preferably, a regulating valve is provided on the smoke exhaust duct, and the regulating valve is located between the heat exchanger and the heat treatment furnace. The regulating valve can control the opening of the smoke exhaust duct, and thus control the flow rate of the smoke in the duct.

[0014] Preferably, a branch pipe is provided on the combustion-supporting air duct, one end of the branch pipe is connected to the combustion-supporting air duct, and the other end is connected to the smoke exhaust air duct. The end of the branch pipe connected to the combustion-supporting air duct is located between the heat exchanger and the cooling air duct on the combustion-supporting air duct, and the end of the branch pipe connected to the smoke exhaust air duct is located between the smoke exhaust fan and the heat exchanger on the smoke exhaust air duct. A manual butterfly valve and an automatic butterfly valve are provided on the branch pipe, and the manual butterfly valve is closer to the combustion-supporting air duct. The manual butterfly valve remains in a normally open state, and the automatic butterfly valve remains in a normally closed state. When the opening of the valve plate is electrically adjusted, especially when the opening of the valve plate is reduced, the pressure in the combustion-supporting air duct will increase. In order to avoid surging of the combustion-supporting fan, when the pressure sensor on the combustion-supporting air duct collects a combustion-supporting air pressure exceeding a preset value, the automatic butterfly valve is opened to discharge the combustion-supporting air to the smoke exhaust duct to avoid surging of the combustion-supporting fan. When the automatic butterfly valve fails, the manual butterfly valve is activated again.

[0015] Preferably, the combustion-supporting air duct is also provided with a pressure sensor and a combustion-supporting air pressure gauge, which are located between the branch pipe and the heat exchanger on the combustion-supporting air duct. The pressure of the combustion-supporting air duct is monitored by the pressure sensor and the combustion-supporting air pressure gauge on the combustion-supporting air duct, thereby realizing the monitoring of the pressure of the combustion-supporting air duct.

[0016] A method for controlling a combustion-supporting air system of a heat treatment furnace comprises the following steps:

[0017] Step 1: First open all valves on the combustion-supporting air duct and the combustion-supporting fan, smoke exhaust fan, and circulating fan to purge the furnace of the heat treatment furnace. After the purge is completed, close the third solenoid valve;

[0018] Step 2: Open the third solenoid valve 3-5s in advance to allow the combustion-supporting air to blow through the burner, then open the gas solenoid valve in front of the burner and ignite. After the flame is detected, stop ignition;

[0019] Step 3: Open the fourth solenoid valve on the cooling air duct, and the cooling air duct provides air cooling to the main shaft bearing of the circulating fan;

[0020] Step 4: Calculate the air-fuel ratio in the heat treatment furnace according to the combustion-supporting air orifice flowmeter and the natural gas orifice flowmeter, and adjust the opening of the electric regulating valve and the proportional valve according to the air-fuel ratio to keep the air-fuel ratio of the heat treatment furnace within the preset range;

[0021] Step 5: Monitor the indication of the pressure sensor. When the indication of the pressure sensor exceeds the preset value, open the automatic butterfly valve on the branch pipe. When the indication of the pressure sensor is less than the preset value, close the automatic butterfly valve on the branch pipe.

[0022] The control method of the combustion-supporting air system of the heat treatment furnace in this scheme can not only reduce the temperature of the main shaft bearing of the circulation fan and complete the adjustment of the air-fuel ratio of the heat treatment furnace when controlling the operation of the combustion-supporting air system of the heat treatment furnace, but also avoid surge of the circulation fan in the system.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: when working, the combustion-supporting air control system of the heat treatment furnace in the present scheme can introduce the airflow in the combustion-supporting air duct into the circulating fan through the cooling air duct to blow the main shaft bearings of the circulating fan, and cool the main shaft bearings of the circulating fan by air, so as to avoid the main shaft bearings of the circulating fan from being overheated and causing the lubricating oil on the main shaft bearings to deteriorate. The staff does not need to frequently replace the lubricating oil on the main shaft bearings, thereby reducing the labor intensity of the staff and avoiding waste of lubricating oil.

[0024] The control method of the combustion-supporting air system of the heat treatment furnace in this scheme can not only reduce the temperature of the main shaft bearing of the circulation fan and complete the adjustment of the air-fuel ratio of the heat treatment furnace when controlling the operation of the combustion-supporting air system of the heat treatment furnace, but also avoid surge of the circulation fan in the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a combustion-supporting air system of a heat treatment furnace of the present invention;

[0026] Figure 2 It is a structural schematic diagram of a main shaft bearing of a combustion-supporting air system of a heat treatment furnace of the present invention;

[0027] Figure 3 The present invention is a flow chart of a method for controlling a combustion-supporting air system of a heat treatment furnace.

[0028] Among them, 1. heat treatment furnace; 2. circulation fan; 3. natural gas pipe; 4. smoke exhaust air duct; 5. combustion-supporting air duct; 6. smoke exhaust fan; 7. combustion-supporting fan; 8. heat exchanger; 9. cooling air duct; 10. main shaft bearing; 11. air-cooled shell; 1101. closed end face; 12. oil filling part; 13. drainage part; 14. fourth solenoid valve; 15. first ball valve; 16. first solenoid valve; 17. solenoid relief valve; 18. natural gas orifice flowmeter; 19. second ball valve; 20. front-mouth gas solenoid valve; 21. proportional valve; 22. linear valve; 23. pressure sensor; 24. combustion-supporting air pressure gauge; 25. combustion-supporting air orifice flowmeter; 26. electric regulating valve; 27. third solenoid valve; 28. air manual butterfly valve; 29. ​​regulating valve; 30. branch pipe; 31. manual butterfly valve; 32. automatic butterfly valve. DETAILED DESCRIPTION

[0029] The drawings are only for illustrative purposes and cannot be construed as limiting the present invention. To better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are only for illustrative purposes and cannot be construed as limiting the present invention.

[0030] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "long", "short" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0031] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0032] Example 1

[0033] like Figure 1 and Figure 2 The figure shows an embodiment of a combustion-supporting air system of a heat treatment furnace, comprising a heat treatment furnace 1, a circulating fan 2 embedded in and installed on the heat treatment furnace 1, a natural gas pipe 3 connected to the inner cavity of the heat treatment furnace 1, a smoke exhaust air duct 4 and a combustion-supporting air duct 5, a smoke exhaust fan 6 connected to the air inlet end of the smoke exhaust air duct 4, a combustion-supporting fan 7 connected to the air inlet end of the combustion-supporting air duct 5, and a heat exchanger 8 for completing heat exchange between the smoke exhaust air duct 4 and the combustion-supporting air duct 5, and an end of the combustion-supporting air duct 5 close to the combustion-supporting fan 7 is also connected to a cooling air duct 9, and an end of the cooling air duct 9 away from the combustion-supporting air duct 5 extends into the interior of the circulating fan 2 to cool the main shaft bearing 10 of the circulating fan 2.

[0034] Specifically, an air-cooling shell 11 is provided on the main shaft bearing 10 of the circulating fan 2, and an annular air-cooling cavity is provided in the air-cooling shell 11. The end of the air-cooling cavity close to the inner cavity of the heat treatment furnace 1 is a closed end face 1101. The lubricating oil on the main shaft bearing 10 is located between the air-cooling shell 11 and the main shaft bearing 10. The end of the cooling air duct 9 connected to the air-cooling shell 11 is located on the outer surface of the air-cooling shell 11, close to the closed end face 1101.

[0035] Specifically, an oil filling portion 12 and a drainage portion 13 are respectively provided at both ends of the air-cooled housing 11. The oil filling portion 12 can guide the lubricating oil to between the air-cooled housing 11 and the main shaft bearing 10, and the drainage portion 13 can guide and collect the lubricating oil between the air-cooled housing 11 and the main shaft bearing 10. The oil filling portion 12 is located at one end of the air-cooled housing 11 close to the closed end face 1101, and the drainage portion 13 is located at one end of the air-cooled housing 11 away from the closed end face 1101. The oil filling portion 12 is an oil filling pipe, and the drainage portion 13 is a drainage pipe. The inlet of the drainage pipe is located at the lowest point of the air-cooled housing 11 in the vertical direction, and the lubricating oil can smoothly flow into the drainage portion 13 by its own gravity.

[0036] The working principle or working process of this embodiment is as follows: when the heat treatment furnace 1 is working, natural gas is transported to the inner cavity of the heat treatment furnace 1 through the natural gas pipe 3, the combustion-supporting fan 7 transports combustion-supporting air to the inner cavity of the heat treatment furnace 1 through the combustion-supporting air duct 5, the circulating fan 2 works to realize the gas circulation in the inner cavity of the heat treatment furnace 1, and then the smoke generated by the combustion in the heat treatment furnace 1 is discharged through the smoke exhaust fan 6 and the smoke exhaust air duct 4. The heat exchanger 8 can transfer the smoke temperature in the smoke exhaust air duct 4 to the combustion-supporting air in the combustion-supporting air duct 5, thereby increasing the temperature of the combustion-supporting air. At the same time, after the combustion-supporting fan 7 starts working, a part of the combustion-supporting air in the combustion-supporting air duct 5 will enter the cooling air duct 9 and move along the cooling air duct 9 until it is discharged from the cooling air duct 9, and the main shaft bearing 10 of the circulating fan 2 is purged, and the heat on the surface of the main shaft bearing 10 is taken away during the purging process, thereby completing the air cooling of the main shaft bearing 10.

[0037] The beneficial effects of this embodiment are as follows: when working, the combustion-supporting air control system of the heat treatment furnace 1 in the scheme can introduce the airflow in the combustion-supporting air duct 5 into the circulating fan 2 through the cooling air duct 9 to blow the main shaft bearing 10 of the circulating fan 2, and cool the main shaft bearing 10 of the circulating fan 2 by air, so as to avoid the main shaft bearing 10 of the circulating fan 2 from being overheated and causing the lubricating oil on the main shaft bearing 10 to deteriorate. The staff does not need to frequently replace the lubricating oil on the main shaft bearing 10, which reduces the labor intensity of the staff and avoids the waste of lubricating oil.

[0038] The setting of the heat exchanger 8 can transfer the heat of the smoke to be discharged from the smoke exhaust duct 4 to the combustion-supporting air in the combustion-supporting air duct 5, thereby increasing the temperature of the combustion-supporting air and preventing the temperature of the inner cavity of the heat treatment furnace 1 from becoming low after the combustion-supporting air enters the heat treatment furnace 1 due to too low a temperature.

[0039] After the heat on the main shaft bearing 10 is dissipated outward and transferred to the air-cooled housing 11, it can be carried away by the airflow flowing in the air-cooled housing 11, avoiding the accumulation of heat, and further avoiding the over-high temperature of the main shaft bearing 10. The setting of the air-cooled housing 11 can prevent the cooling air from blowing directly on the main shaft bearing 10 and blowing away the lubricating oil on the main shaft bearing 10. The closed end face 1101 on the air-cooled housing 11 is close to the inner cavity of the heat treatment furnace 1, which can prevent the cooling air from blowing into the heat treatment furnace 1 along the circulating fan. The setting of the oil filling part 12 and the drainage part 13 facilitates the filling and replacement of the lubricating oil on the main shaft bearing 10.

[0040] Example 2

[0041] Embodiment 2 of a combustion-supporting air system for a heat treatment furnace, based on embodiment 1, as Figure 1 As shown, the structure of the pipeline is further limited.

[0042] Specifically, a natural gas orifice flow meter 18, a second ball valve 19, a front-mouth gas solenoid valve 20, a proportional valve 21 and a linear valve 22 are sequentially arranged on the natural gas pipe 3, wherein the linear valve 22 is closest to the heat treatment furnace 1; a combustion-supporting air orifice flow meter 25, an electric regulating valve 26, a third solenoid valve 27 and an air manual butterfly valve 28 are sequentially arranged on the combustion-supporting air duct 5 between the heat treatment furnace 1 and the heat exchanger 8, wherein the air manual butterfly valve 28 is closest to the heat treatment furnace 1, and the front-mouth gas solenoid valve 20 and the third solenoid valve 27 are both quick-opening and quick-breaking solenoid valves.

[0043] Specifically, the natural gas pipe 3 is also provided with a first ball valve 15, a first solenoid valve 16 and an electromagnetic relief valve 17. The first ball valve 15, the first solenoid valve 16, the electromagnetic relief valve 17, the natural gas orifice flow meter 18, the second ball valve 19, the front-mouth gas solenoid valve 20, the proportional valve 21 and the linear valve 22 are arranged in sequence on the natural gas pipe 3.

[0044] Specifically, the proportional valve 21 is also connected to a collection pipe, the other end of which is connected to the combustion-supporting air pipe 5, and one end of the collection pipe connected to the combustion-supporting air pipe 5 is located between the third solenoid valve 27 and the air manual butterfly valve 28. The exhaust air pipe 4 is provided with a regulating valve 29, which is located between the heat exchanger 8 and the heat treatment furnace 1.

[0045] Specifically, a branch pipe 30 is provided on the combustion-supporting air duct 5, one end of the branch pipe 30 is connected to the combustion-supporting air duct 5, and the other end is connected to the smoke exhaust air duct 4. The end of the branch pipe 30 connected to the combustion-supporting air duct 5 is located between the heat exchanger 8 and the cooling air duct 9 on the combustion-supporting air duct 5, and the end of the branch pipe 30 connected to the smoke exhaust air duct 4 is located between the smoke exhaust fan 6 and the heat exchanger 8 on the smoke exhaust air duct 4. A manual butterfly valve 31 and an automatic butterfly valve 32 are provided on the branch pipe 30, and the manual butterfly valve 31 is closer to the combustion-supporting air duct 5. The manual butterfly valve 31 is kept in a normally open state, and the automatic butterfly valve 32 is kept in a normally closed state. A pressure sensor 23 and a combustion-supporting air pressure gauge 24 are also provided on the combustion-supporting air duct 5, and the pressure sensor 23 and the combustion-supporting air pressure gauge 24 are located between the branch pipe 30 and the heat exchanger 8 on the combustion-supporting air duct 5.

[0046] Beneficial effects of this embodiment: When the heat treatment furnace 1 is working, the ratio of natural gas and combustion-supporting air entering the inner cavity of the heat treatment furnace 1 is obtained through the natural gas orifice flowmeter 18 and the combustion-supporting air orifice flowmeter 25. When the ratio of natural gas and combustion-supporting air is out of balance, the opening of the natural gas pipe 3 is adjusted by the proportional valve 21 and the linear valve 22, and the opening of the combustion-supporting air pipe 5 is adjusted by the electric regulating valve 26, so as to achieve the purpose of adjusting the flow of natural gas and combustion-supporting air, and then adjust the ratio of natural gas and combustion-supporting air, so as to achieve the precise ratio of natural gas and combustion-supporting air, so that the heat treatment furnace 1 can be fully burned, and the purpose of energy saving and consumption reduction is achieved. The front-mouth gas solenoid valve 20 and the third solenoid valve 27 are both fast-opening and fast-breaking solenoid valves. When the temperature in the heat treatment furnace 1 reaches the process temperature, the front-mouth gas solenoid valve 20 quickly cuts off the gas supply. After the burner is extinguished, the combustion-supporting air continues to blow for 3-5s, and then the third solenoid valve 27 quickly cuts off the combustion-supporting air supply, so as to avoid the combustion-supporting air from continuously entering the furnace and causing the temperature in the furnace to drop rapidly.

[0047] The ball valve and the solenoid valve can control the opening and closing of the natural gas pipe 3 to prevent the natural gas pipe 3 from being unable to open and close normally due to damage to a certain valve. The electromagnetic relief valve 17 can release pressure and deflate air when the pressure in the pipe is too high to prevent the explosion caused by excessive pressure in the pipe during the transportation of natural gas. After the collection pipe is connected to the proportional valve 21, it can monitor whether the third solenoid valve 27 is completely closed. The regulating valve 29 can control the opening of the smoke exhaust duct 4, thereby controlling the flow rate of the smoke in the pipe.

[0048] When the electric regulating valve 26 is opened, especially when the valve plate opening is reduced, the pressure in the combustion-supporting air duct 5 will increase. To prevent the combustion-supporting fan 7 from surging, when the pressure sensor 23 on the combustion-supporting air duct 5 collects the combustion-supporting air pressure exceeding the preset value, the automatic butterfly valve 32 is opened to discharge the combustion-supporting air to the smoke exhaust duct to prevent the combustion-supporting fan 7 from surging. When the automatic butterfly valve 32 fails, the manual butterfly valve 31 is activated. The pressure of the combustion-supporting air duct 5 is monitored by the pressure sensor 23 and the combustion-supporting air pressure gauge 24 on the combustion-supporting air duct 5, so as to realize the monitoring of the pressure of the combustion-supporting air duct 5.

[0049] Example 3

[0050] An embodiment of a method for controlling a combustion-supporting air system of a heat treatment furnace as shown in Example 2, as shown in Figure 3 As shown, the following steps are included:

[0051] Step 1: first open all valves on the combustion-supporting air duct 5 and the combustion-supporting fan 7, the smoke exhaust fan 6, and the circulating fan 2 to purge the furnace of the heat treatment furnace 1, and then close them after the purge is completed, and close the third solenoid valve 27;

[0052] Step 2: Open the third solenoid valve 27 3-5 seconds in advance to allow the combustion-supporting air to blow through the burner, then open the gas solenoid valve 20 in front of the burner and ignite. After the flame is detected, stop ignition;

[0053] Step 3: Open the fourth solenoid valve 14 on the cooling air duct 9, so that the cooling air duct 9 provides air cooling to the main shaft bearing 10 of the circulating fan 2;

[0054] Step 4: Calculate the air-fuel ratio in the heat treatment furnace 1 according to the combustion air orifice flowmeter 25 and the natural gas orifice flowmeter 18, and adjust the opening of the electric regulating valve 26 and the proportional valve 21 according to the air-fuel ratio, so that the air-fuel ratio of the heat treatment furnace 1 is maintained within a preset range;

[0055] Step 5: Monitor the reading of the pressure sensor 23. When the reading of the pressure sensor 23 exceeds the preset value, open the automatic butterfly valve 32 on the branch pipe 30. When the reading of the pressure sensor 23 is less than the preset value, close the automatic butterfly valve 32 on the branch pipe 30.

[0056] Beneficial effects of this embodiment: When controlling the operation of the combustion-supporting air system of the heat treatment furnace 1, the control method of the combustion-supporting air system in this embodiment can not only reduce the temperature of the main shaft bearing 10 of the circulating fan and complete the adjustment of the air-fuel ratio of the heat treatment furnace 1, but also avoid surge of the circulating fan in the system.

[0057] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A combustion-supporting air system for a heat treatment furnace, It is characterized in that The invention comprises a heat treatment furnace (1), a circulation fan (2) embedded in the heat treatment furnace (1), a natural gas pipe (3) connected to the inner cavity of the heat treatment furnace (1), a smoke exhaust duct (4) and a combustion-supporting duct (5), as well as a smoke exhaust fan (6) connected to the air inlet end of the smoke exhaust duct (4), a combustion-supporting fan (7) connected to the air inlet end of the combustion-supporting duct (5), and a heat exchanger (8) for completing heat exchange between the smoke exhaust duct (4) and the combustion-supporting duct (5); an end of the combustion-supporting duct (5) close to the combustion-supporting fan (7) is also connected to a cooling duct (9); an end of the cooling duct (9) away from the combustion-supporting duct (5) extends into the interior of the circulation fan (2) to cool the main shaft bearing (10) of the circulation fan (2).

2. A combustion-supporting air system for a heat treatment furnace according to claim 1, It is characterized in that An air-cooling shell (11) is sleeved on the main shaft bearing (10) of the circulating fan (2), and an annular air-cooling cavity is arranged in the air-cooling shell (11); one end of the air-cooling cavity close to the inner cavity of the heat treatment furnace (1) is a closed end face (1101); the lubricating oil on the main shaft bearing (10) is located between the air-cooling shell (11) and the main shaft bearing (10); and one end of the cooling air duct (9) connected to the air-cooling shell (11) is located on the outer side of the air-cooling shell (11) close to the closed end face (1101).

3. A combustion-supporting air system for a heat treatment furnace according to claim 2, It is characterized in that The two ends of the air-cooled housing (11) are respectively provided with an oil injection portion (12) and a drainage portion (13); the oil injection portion (12) can guide the lubricating oil to between the air-cooled housing (11) and the main shaft bearing (10); the drainage portion (13) can guide and collect the lubricating oil between the air-cooled housing (11) and the main shaft bearing (10); the oil injection portion (12) is located at one end of the air-cooled housing (11) close to the closed end face (1101); and the drainage portion (13) is located at one end of the air-cooled housing (11) far from the closed end face (1101).

4. The combustion-supporting air system of a heat treatment furnace according to claim 1, It is characterized in that The natural gas pipe (3) is provided with a natural gas orifice flow meter (18), a second ball valve (19), a front-end gas solenoid valve (20), a proportional valve (21) and a linear valve (22) in sequence, wherein the linear valve (22) is closest to the heat treatment furnace (1); the combustion-supporting air orifice flow meter (25), an electric regulating valve (26), a third solenoid valve (27) and an air manual butterfly valve (28) are provided in sequence on the combustion-supporting air pipe (5) between the heat treatment furnace (1) and the heat exchanger (8), wherein the third solenoid valve (27) and the air manual butterfly valve (28) are closest to the heat treatment furnace (1), and the front-end gas solenoid valve (20) and the third solenoid valve (27) are both quick-opening and quick-closing solenoid valves.

5. A combustion-supporting air system for a heat treatment furnace according to claim 4, It is characterized in that The natural gas pipe (3) is also provided with a first ball valve (15), a first solenoid valve (16) and an electromagnetic relief valve (17); the first ball valve (15), the first solenoid valve (16), the electromagnetic relief valve (17), the natural gas orifice flow meter (18), the second ball valve (19), the front-mouth gas solenoid valve (20), the proportional valve (21) and the linear valve (22) are arranged in sequence on the natural gas pipe (3).

6. A combustion-supporting air system for a heat treatment furnace according to claim 4, It is characterized in that The proportional valve (21) is also connected to a collection pipe, the other end of which is connected to the combustion-supporting air pipe (5), and the end of the collection pipe connected to the combustion-supporting air pipe (5) is located between the third solenoid valve (27) and the air manual butterfly valve (28).

7. The combustion-supporting air system of a heat treatment furnace according to claim 4, It is characterized in that The smoke exhaust duct (4) is provided with a regulating valve (29), and the regulating valve (29) is located between the heat exchanger (8) and the heat treatment furnace (1).

8. A combustion-supporting air system for a heat treatment furnace according to any one of claims 4 to 7, It is characterized in that The combustion-supporting air duct (5) is provided with a branch pipe (30), one end of the branch pipe (30) is connected to the combustion-supporting air duct (5), and the other end is connected to the smoke exhaust air duct (4); the end of the branch pipe (30) connected to the combustion-supporting air duct (5) is located between the heat exchanger (8) and the cooling air duct (9) on the combustion-supporting air duct (5); the end of the branch pipe (30) connected to the smoke exhaust air duct (4) is located between the smoke exhaust fan (6) and the heat exchanger (8) on the smoke exhaust air duct (4); the branch pipe (30) is provided with a manual butterfly valve (31) and an automatic butterfly valve (32); the manual butterfly valve (31) is closer to the combustion-supporting air duct (5).

9. A combustion-supporting air system for a heat treatment furnace according to claim 8, It is characterized in that The combustion-supporting air duct (5) is also provided with a pressure sensor (23) and a combustion-supporting air pressure gauge (24); the pressure sensor (23) and the combustion-supporting air pressure gauge (24) are located between the branch pipe (30) and the heat exchanger (8) on the combustion-supporting air duct (5).

10. A method for controlling a combustion-supporting air system of a heat treatment furnace as claimed in claim 9, It is characterized in that The steps include: Step 1: First, open all valves on the combustion-supporting air duct (5) and the combustion-supporting fan (7), the smoke exhaust fan (6), and the circulation fan (2) to purge the furnace of the heat treatment furnace (1), and then close the third solenoid valve (27) after the purge is completed; Step 2: Open the third solenoid valve (27) 3-5 seconds in advance to allow the combustion-supporting air to blow through the burner, then open the gas solenoid valve (20) in front of the burner and ignite. After the flame is detected, stop ignition. Step 3: Open the fourth solenoid valve (14) on the cooling air duct (9), so that the cooling air duct (9) cools the main shaft bearing (10) of the circulating fan (2); Step 4: Calculate the air-fuel ratio in the heat treatment furnace (1) according to the combustion-supporting air orifice flow meter (25) and the natural gas orifice flow meter (18), and adjust the opening of the electric regulating valve (26) and the proportional valve (21) according to the air-fuel ratio, so that the air-fuel ratio of the heat treatment furnace (1) is maintained within a preset range; Step 5: Monitor the reading of the pressure sensor (23). When the reading of the pressure sensor (23) exceeds a preset value, open the automatic butterfly valve (32) on the branch pipe (30). When the reading of the pressure sensor (23) is less than the preset value, close the automatic butterfly valve (32) on the branch pipe (30).

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