An indirect hot blast stove that adjusts temperature with circulating air

Abstract

The present invention belongs to the technical field of hot blast stoves, and discloses an indirect hot blast stove for regulating temperature with circulating air, which includes a hot air box and a plate heat exchanger. The hot air box and the plate heat exchanger are connected through a first connecting pipe and a second connecting pipe. A burner is fixedly installed on the left side of the hot air box. A sealing box and a mixing box are successively and fixedly installed on the left and right sides of the inner wall of the hot air box. A fire protection cylinder is fixedly installed inside the hot air box. Through the heat exchange of the clean air and the circulating air by the first heat exchange plate and the second heat exchange plate, the present invention can reduce the temperature of the high-temperature flue gas mixed with the circulating air, and heat the clean air so that it can become the production-use air, saving the energy cost. It also reduces the damage to the equipment by reducing the temperature of the high-temperature flue gas. Most of the circulating air is sent into the mixing box by a centrifugal fan, and a small part of the circulating air with the same air volume as the high-temperature flue gas is discharged along the smoke outlet, maintaining the air volume of the circulating air.

Description

Technical Field

[0001] The invention belongs to the technical field of hot blast stoves, and particularly relates to an indirect hot blast stove for regulating temperature with circulating air. Background Art

[0002] A hot blast stove can heat the blast air to the required temperature and discharge it. At present, when a traditional indirect hot blast stove is working, if the air volume on the cold side suddenly decreases significantly, that is, the heat taken away suddenly decreases, the control system needs adjustment time. At this time, the hot side still maintains the original working condition, and the high-temperature flue gas will continue to heat up, burning out the heat exchange elements of the heat exchanger. The high-temperature side of the traditional indirect hot blast stove uses natural gas to heat the normal-temperature gas to 600 degrees, and after heat exchange through a plate heat exchanger, it is reduced to 300 degrees and directly discharged, resulting in relatively high operating costs. Therefore, it is necessary to design an indirect hot blast stove that reduces the risk brought by the excessive temperature of the high-temperature flue gas after the burner burns. Summary of the Invention

[0003] The purpose of the invention is to provide an indirect hot blast stove for regulating temperature with circulating air to solve the problems raised in the above background art.

[0004] To achieve the above purpose, the invention provides the following technical solution: An indirect hot blast stove for regulating temperature with circulating air, including a hot air box and a plate heat exchanger. The hot air box and the plate heat exchanger are connected through a first connecting pipe and a second connecting pipe. A burner is fixedly installed on the left side of the hot air box. A sealing box and a mixing box are fixedly installed on the left and right sides of the inner wall of the hot air box in sequence. A fire protection cylinder is fixedly installed inside the hot air box. A mixer is fixedly installed inside the mixing box. Air inlets are formed on the upper and lower sides of the mixer. A first air inlet pipe is installed on the front of the hot air box. An air outlet box and an air inlet box are connected in sequence on the front and back sides of the plate heat exchanger. An air outlet pipe and a second air inlet pipe are fixedly connected to the tops of the air outlet box and the air inlet box respectively. A first heat exchange plate and a second heat exchange plate are fixedly connected to the front and back sides of the inner wall of the plate heat exchanger respectively. A first fixing ring and a first sealing ring are fixedly connected to the surface of the first heat exchange plate. A second fixing ring and a second sealing ring are fixedly connected to the surface of the second heat exchange plate.

[0005] Preferably, the hot air box and the plate heat exchanger are distributed front and back. The second connecting pipe and the first connecting pipe are distributed left and right between the hot air box and the plate heat exchanger. A smoke outlet is fixedly installed on the top of the hot air box. The second connecting pipe is connected to a centrifugal fan. The mixer is connected to the first connecting pipe.

[0006] Preferably, the number of the first heat exchange plates is nine, and the number of the second heat exchange plates is eight. The nine first heat exchange plates and the eight second heat exchange plates are distributed in an equidistant and staggered manner. Through grooves are formed inside both the first heat exchange plates and the second heat exchange plates. Through-type communication ports are formed on both the front and rear sides of the plate heat exchanger. The air inlet box and the air outlet box are communicated with the through grooves through the communication ports.

[0007] Preferably, both the first sealing ring and the second sealing ring are made of rubber blocks, both the first fixing ring and the second fixing ring are made of fiber materials, and the first sealing ring and the second sealing ring are in extrusion contact between the first fixing ring and the second fixing ring.

[0008] Preferably, the left end of the fire protection cylinder is communicated with the inner cavity of the mixing box, and the left end of the fire protection cylinder is communicated with the inner cavity of the hot air box.

[0009] Preferably, both the first heat exchange plate and the second heat exchange plate are made by stamping aluminum metal, and the horizontal cross-sectional shapes of both the first heat exchange plate and the second heat exchange plate are "U" shaped.

[0010] Preferably, the distance value between each adjacent first heat exchange plate and second heat exchange plate is equal to the sum of the height values of the first fixing ring and the second fixing ring.

[0011] Preferably, the same gaps are left between the upper and lower sides of the mixer and the upper and lower sides of the inner wall of the hot air box respectively.

[0012] Preferably, bell mouths are provided on both the left side of the centrifugal fan and the right side of the burner. The smoke outlet is located directly above the left side of the centrifugal fan, and the temperature of the circulating air is 300 degrees.

[0013] The beneficial effects of the present invention are as follows:

[0014] 1. The present invention introduces circulating air at 300 degrees through a first air inlet pipe and mixes it with high-temperature flue gas at 600 degrees from a burner, which can quickly adjust to a suitable temperature, protect the plate heat exchanger, and at the same time reduce gas consumption. The mixed circulating air and high-temperature flue gas are introduced into the inner cavity of the plate heat exchanger through a mixing box and a mixer. The circulating air moves along path ① through the first heat exchange plates and the second heat exchange plates arranged in a staggered front-back manner, making it fully contact with the surfaces of the first heat exchange plates and the second heat exchange plates. Then, clean air is introduced through an air inlet box and a second air inlet pipe. The clean air enters the inside of the second heat exchange plate along the second air inlet pipe, then enters the inside of the first heat exchange plate through a first sealing ring and a second sealing ring, and finally enters the air outlet box and is discharged. During this process, the clean air and the circulating air exchange heat through the first heat exchange plates and the second heat exchange plates, which can reduce the temperature of the high-temperature flue gas mixed with the circulating air and heat the clean air to make it suitable for production use, saving energy costs. It also reduces the damage to the equipment by reducing the temperature of the high-temperature flue gas. Most of the circulating air is sent into the mixing box by a centrifugal fan, and a small part of the circulating air with the same air volume as the high-temperature flue gas is discharged along the smoke outlet, maintaining the air volume of the circulating air.

[0015] 2. Then, by setting a mixer, the mixing speed of the high-temperature flue gas and the circulating air entering the inner cavity of the mixing box is accelerated. Along with the high-temperature flue gas and positive pressure generated by the burner, the high-temperature flue gas and the circulating air enter the inside of the mixer from the upper and lower directions along the air inlet, and two airflows with different mixing degrees collide up and down, making the mixing degree of the high-temperature flue gas and the circulating air in the inner cavity of the mixing box higher, the mixing time shorter, and the mixing efficiency higher, enabling the circulating air at 300 degrees to quickly reduce the high-temperature flue gas at 600 degrees to a suitable temperature.

[0016] 3. Finally, the first fixing ring and the second fixing ring with the same height wrap the first sealing ring and the second sealing ring to connect the first heat exchange plate and the second heat exchange plate. On the basis of fixedly connecting the first heat exchange plate and the second heat exchange plate to the inner wall of the plate heat exchanger, not only can the heat exchange operation be completed, but also the first fixing ring and the second fixing ring provide sufficient pressing and fixing support for the first heat exchange plate and the second heat exchange plate. The first heat exchange plate and the second heat exchange plate made of aluminum metal change the form of the heat exchange medium, replacing the traditional heat exchange logic of fluid contact with the form of increasing the flow of hot air, which not only improves the heat exchange efficiency but also reduces the self-weight of the equipment and is convenient for transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a front three-dimensional schematic diagram of the overall structure of the present invention;

[0018] Figure 2 is a schematic diagram of the internal structure of the hot air box of the present invention;

[0019] Figure 3Schematic diagram of the horizontal internal structure of the hot air box and the plate heat exchanger of the present invention;

[0020] Figure 4 Back view schematic diagram of the internal structure of the hot air box of the present invention;

[0021] Figure 5 Horizontal sectional view schematic diagram of the plate heat exchanger of the present invention;

[0022] Figure 6 For the present invention Figure 5 Enlarged schematic diagram of the structure at position A in

[0023] Figure 7 Sectional view schematic diagram of the mixer of the present invention;

[0024] Figure 8 Separation schematic diagram of the first heat exchange plate, the second heat exchange plate, the first fixing ring, the second fixing ring, the first sealing ring and the second sealing ring of the present invention;

[0025] Figure 9 Flow schematic diagram of the circulating air, clean air and high-temperature flue gas of the present invention.

[0026] In the figure: 1. Hot air box; 2. Smoke outlet; 3. First air inlet pipe; 4. Burner; 5. First connecting pipe; 6. Plate heat exchanger; 7. Air inlet box; 8. Second air inlet pipe; 9. Air outlet box; 10. Air outlet pipe; 11. Sealing box; 12. Centrifugal fan; 13. Fire protection cylinder; 14. Mixing box; 15. Mixer; 16. Air inlet; 17. First heat exchange plate; 18. Second heat exchange plate; 19. Through groove; 20. First fixing ring; 21. Second fixing ring; 22. First sealing ring; 23. Second sealing ring; 24. Second connecting pipe; 25. Connecting port. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying 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 the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0028] Such as Figures 1 to 9As shown in the figure, an embodiment of the present invention provides an indirect hot blast stove for adjusting temperature with circulating air, which includes a hot air box 1 and a plate heat exchanger 6. The hot air box 1 and the plate heat exchanger 6 are connected through a first connecting pipe 5 and a second connecting pipe 24. A burner 4 is fixedly installed on the left side of the hot air box 1. A sealing box 11 and a mixing box 14 are fixedly installed in sequence on the left and right sides of the inner wall of the hot air box 1. A fire protection cylinder 13 is fixedly installed inside the hot air box 1. A mixer 15 is fixedly installed inside the mixing box 14. Air inlets 16 are formed on both the upper and lower sides of the mixer 15. A first air inlet pipe 3 is installed on the front of the hot air box 1. An air outlet box 9 and an air inlet box 7 are connected in sequence on the front and back sides of the plate heat exchanger 6. An air outlet pipe 10 and a second air inlet pipe 8 are fixedly connected to the tops of the air outlet box 9 and the air inlet box 7 respectively. A first heat exchange plate 17 and a second heat exchange plate 18 are fixedly connected in sequence on the front and back sides of the inner wall of the plate heat exchanger 6. A first fixing ring 20 and a first sealing ring 22 are fixedly connected to the surface of the first heat exchange plate 17. A second fixing ring 21 and a second sealing ring 23 are fixedly connected to the surface of the second heat exchange plate 18;

[0029] When the device is working, combustion-supporting air and natural gas are introduced into the burner 4 to burn and generate high-temperature flue gas. The circulating air introduced by the first air inlet pipe 3 is mixed with the high-temperature flue gas from the burner 4 through the mixing box 14 for preliminary cooling, and then enters the inside of the plate heat exchanger 6 through the mixer 15. Through the unique air duct ① formed by the cooperation of the first heat exchange plate 17 and the second heat exchange plate 18 with the plate heat exchanger 6, the high-temperature flue gas and the circulating air can flow along one path and pass through the surfaces of the first heat exchange plate 17 and the second heat exchange plate 18, which helps to fully heat the first heat exchange plate 17 and the second heat exchange plate 18. By connecting the air inlet box 7 and the air outlet box 9 to the plate heat exchanger 6, the clean air enters the inside of the second heat exchange plate 18 along the second air inlet pipe 8, then enters the inside of the first heat exchange plate 17 through the first sealing ring 22 and the second sealing ring 23, and finally enters the air outlet box 9 and is discharged. During this process, the clean air and the circulating air exchange heat through the first heat exchange plate 17 and the second heat exchange plate 18, which can reduce the temperature of the high-temperature flue gas mixed with the circulating air, and heat the clean air to make it become production-use air, saving energy costs. It also reduces the damage to the equipment by reducing the temperature of the high-temperature flue gas. Most of the circulating air is sent into the mixing box 14 by the centrifugal fan 12, and a small part of the circulating air with the same air volume as the high-temperature flue gas is discharged along the smoke outlet 2, maintaining the air volume of the circulating air.

[0030] By setting up the mixer 15, the mixing speed of the high-temperature flue gas and the circulating air entering the inner cavity of the mixing box 14 is accelerated. With the high temperature and positive pressure generated by the burner 4, the high-temperature flue gas and the circulating air enter the inside of the mixer 15 from the upper and lower directions along the air inlet 16, and two gas flows with low mixing degree collide with each other up and down, making the mixing degree of the high-temperature flue gas and the circulating air higher in the inner cavity of the mixing box 14, the mixing time shorter, and the mixing efficiency higher, so that the 300-degree circulating air can quickly reduce the 600-degree high-temperature flue gas to an appropriate temperature.

[0031] Among them, the hot air box 1 and the plate heat exchanger 6 are distributed front and back, the second connecting pipe 24 and the first connecting pipe 5 are distributed left and right between the hot air box 1 and the plate heat exchanger 6. The top of the hot air box 1 is fixedly installed with a smoke outlet 2. The second connecting pipe 24 is communicated with the centrifugal fan 12, and the mixer 15 is communicated with the first connecting pipe 5;

[0032] The air outlet end of the hot air box 1 is located on one side of the first connecting pipe 5, and the air inlet end of the hot air box 1 is located on one side of the second connecting pipe 24. One in and one out can send the circulating air back. The high-temperature flue gas and the circulating air after mixing are sent into the inner cavity of the plate heat exchanger 6 along the first connecting pipe 5, and the heat exchange operation is completed through the first heat exchange plate 17 and the second heat exchange plate 18.

[0033] Among them, the number of the first heat exchange plates 17 is nine, and the number of the second heat exchange plates 18 is eight. Nine first heat exchange plates 17 and eight second heat exchange plates 18 are arranged at equal intervals and staggered. Through grooves 19 are opened inside the first heat exchange plates 17 and the second heat exchange plates 18. Through-type communication ports 25 are opened on the front and back sides of the plate heat exchanger 6. The air inlet box 7 and the air outlet box 9 are communicated with the through grooves 19 through the communication ports 25;

[0034] Nine first heat exchange plates 17 and eight second heat exchange plates 18 are arranged in a front and back staggered manner, so that the high-temperature flue gas and the circulating air entering the inner cavity of the plate heat exchanger 6 can extend the flowing time in the inner cavity of the plate heat exchanger 6 along the air duct ①, increase the heat exchange efficiency of the first heat exchange plates 17 and the second heat exchange plates 18, and quickly reduce the high-temperature flue gas to an appropriate temperature to avoid damage to the equipment.

[0035] Among them, the first sealing ring 22 and the second sealing ring 23 are both made of rubber blocks, the first fixing ring 20 and the second fixing ring 21 are both made of fiber materials, and the first sealing ring 22 and the second sealing ring 23 are in extrusion contact between the first fixing ring 20 and the second fixing ring 21;

[0036] The first sealing ring 22 and the second sealing ring 23 are both made of rubber blocks. Through extrusion deformation and under the limit protection of the first fixing ring 20 and the second fixing ring 21, the sealing channel between the first sealing ring 22 and the second sealing ring 23 is maintained, which is used to connect the interiors of the adjacent first heat exchange plate 17 and the second heat exchange plate 18. The clean air can fully contact the first heat exchange plate 17 and the second heat exchange plate 18 and perform heat exchange operations when passing through the inside of the through groove 19.

[0037] Among them, the left end of the fire protection cylinder 13 is communicated with the inner cavity of the mixing box 14, and the left end of the fire protection cylinder 13 is communicated with the inner cavity of the hot air box 1;

[0038] The fire protection cylinder 13 is used to protect the flame ignited by the burner 4. Through aggregation, the combustion direction of the flame and the direction of the generated flue gas point to the inside of the mixing box 14. The flared opening on the right side of the burner 4 can help the air flow to enter and improve the combustion efficiency of fuels such as natural gas.

[0039] Among them, the first heat exchange plate 17 and the second heat exchange plate 18 are both made of aluminum metal by stamping, and the horizontal cross-sectional shapes of the first heat exchange plate 17 and the second heat exchange plate 18 are both "U" shaped;

[0040] The first heat exchange plate 17 and the second heat exchange plate 18 are both made of aluminum metal, which has the advantage of high temperature resistance and can achieve the purpose of effective heat exchange. Moreover, the aluminum metal is light in weight, which can reduce the weight of the equipment and facilitate transportation. The second heat exchange plate 18 is communicated with the rear side of the inner wall of the plate heat exchanger 6, and the first heat exchange plate 17 is communicated with the front side of the inner wall of the plate heat exchanger 6. Through the interlaced design of the first heat exchange plate 17 and the second heat exchange plate 18, the contact time and heat exchange area between the circulating air and the surfaces of the first heat exchange plate 17 and the second heat exchange plate 18 can be increased, so as to achieve the purpose of increasing the heat exchange efficiency.

[0041] Among them, the distance value between each adjacent first heat exchange plate 17 and second heat exchange plate 18 is equal to the sum of the height values of the first fixing ring 20 and the second fixing ring 21;

[0042] The height values of the first fixing ring 20 and the second fixing ring 21 are the same, and the height value is the left and right height values of the first fixing ring 20 and the second fixing ring 21. The distance value between each adjacent first heat exchange plate 17 and second heat exchange plate 18 is equal to the sum of the height values of the first fixing ring 20 and the first fixing ring 20. In the inner cavity of the plate heat exchanger 6, the fixedly installed first heat exchange plate 17 and second heat exchange plate 18 can not only be connected through the first fixing ring 20 and the second fixing ring 21, and clean air is introduced to complete the heat exchange operation, but also provide sufficient supporting effect through the first fixing ring 20 and the second fixing ring 21.

[0043] Among them, the upper and lower sides of the mixer 15 respectively have the same gaps with the upper and lower sides of the inner wall of the hot air box 1;

[0044] The mixer 15 is used to assist in mixing the high-temperature flue gas and the circulating air entering the inner cavity of the mixing box 14. There are two air inlets 16, which are respectively distributed on the upper and lower sides of the mixer 15. The mixed gas inside the mixing box 14 enters the inner cavity of the mixer 15 from the two air inlets 16, forming an up-and-down air convection to achieve the purpose of accelerating the mixing efficiency.

[0045] Among them, bell mouths are provided on the left side of the centrifugal fan 12 and the right side of the burner 4. The smoke outlet 2 is directly above the left side of the centrifugal fan 12, and the temperature of the circulating air is 300 degrees.

[0046] The bell mouth on the right side of the burner 4 can help the air flow to enter and improve the combustion efficiency of fuels such as natural gas.

[0047] Working principle and usage process:

[0048] First, fresh circulating air is introduced into the inner cavity of the mixing box 14 through the first air inlet pipe 3, natural gas and combustion-supporting air are introduced into the burner 4, high-temperature flue gas is generated and enters the inside of the mixing box 14 along the fire protection cylinder 13. The high-temperature flue gas and the circulating air are mixed inside the mixing box 14, and the mixture enters the inside of the mixer 15 through the two upper and lower air inlets 16 opened on the surface of the mixer 15 respectively, forming an air convection to reduce the temperature of the flue gas. The centrifugal fan 12 is turned on to generate a positive pressure in the inner cavity of the hot air box 1 and blow outwards. After mixing with the circulating air, the cooled flue gas enters the inner cavity of the plate heat exchanger 6 through the first connecting pipe 5.

[0049] Then, the centrifugal fan 12 generates a negative pressure in the inner cavity of the plate heat exchanger 6. As Figure 4 shown, the circulating air and the high-temperature flue gas entering the inner cavity of the plate heat exchanger 6 move along the path ① and continuously heat the outer surfaces of the first heat exchange plate 17 and the second heat exchange plate 18. The first heat exchange plate 17 and the second heat exchange plate 18 on the right side are preferentially heated. As the circulating air flows, all the first heat exchange plates 17 and the second heat exchange plates 18 are fully heated. Clean air is introduced through the second air inlet pipe 8. After entering the inner cavity of the air inlet box 7, it enters the through groove 19 through the communication port 25. The clean air first enters the inside of the second heat exchange plate 18 and is heated through the inner wall of the second heat exchange plate 18 for heat exchange, then enters the inside of the first heat exchange plate 17 through the second sealing ring 23 and the first sealing ring 22 for further heat exchange, and then enters the air outlet box 9 and is discharged through the air outlet pipe 10. The clean air after heat exchange can be used as production air.

[0050] Finally, the circulating air and the high-temperature flue gas that have exchanged heat through the plate heat exchanger 6 are cooled to an appropriate temperature, and then transported to the inside of the sealed box 11 through the second connecting pipe 24. The potential energy is increased by centrifugation through the centrifugal fan 12, and most of it returns to the inside of the mixing box 14 along the fire protection cylinder 13, and a small part is discharged along the smoke outlet 2. Its air volume is equivalent to that of the high-temperature flue gas, which can maintain the temperature of the circulating air and reduce the risk to the plate heat exchanger 6 caused by the excessively high temperature of the high-temperature flue gas after combustion of the burner 4.

[0051] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0052] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An indirect hot blast stove for regulating temperature with circulating air, comprising a hot air box (1) and a plate heat exchanger (6), wherein the hot air box (1) and the plate heat exchanger (6) are communicated through a first connecting pipe (5) and a second connecting pipe (24), and it is characterized in that: A burner (4) is fixedly installed on the left side of the hot air box (1). On the left and right sides of the inner wall of the hot air box (1), a sealing box (11) and a mixing box (14) are fixedly installed in sequence. A fire protection cylinder (13) is fixedly installed inside the hot air box (1). A mixer (15) is fixedly installed inside the mixing box (14). Air inlets (16) are formed on both the upper and lower sides of the mixer (15). A first air inlet pipe (3) is installed on the front of the hot air box (1). An air outlet box (9) and an air inlet box (7) are connected in sequence and communicated on the front and back sides of the plate heat exchanger (6). An air outlet pipe (10) and a second air inlet pipe (8) are fixedly connected to the tops of the air outlet box (9) and the air inlet box (7) respectively. A first heat exchange plate (17) and a second heat exchange plate (18) are fixedly connected in sequence on the front and back sides of the inner wall of the plate heat exchanger (6). A first fixing ring (20) and a first sealing ring (22) are fixedly connected to the surface of the first heat exchange plate (17). A second fixing ring (21) and a second sealing ring (23) are fixedly connected to the surface of the second heat exchange plate (18). The number of the first heat exchange plates (17) is nine, and the number of the second heat exchange plates (18) is eight. The nine first heat exchange plates (17) and the eight second heat exchange plates (18) are distributed at equal intervals and staggered. Through grooves (19) are formed inside both the first heat exchange plate (17) and the second heat exchange plate (18). Through-type communication ports (25) are formed on both the front and back sides of the plate heat exchanger (6). The air inlet box (7) and the air outlet box (9) are communicated with the through grooves (19) through the communication ports (25). Both the first sealing ring (22) and the second sealing ring (23) are made of rubber blocks. Both the first fixing ring (20) and the second fixing ring (21) are made of fiber materials. The first sealing ring (22) and the second sealing ring 23 are in extrusion contact between the first fixing ring (20) and the second fixing ring (21). The distance value between adjacent first heat exchange plates (17) and second heat exchange plates (18) is equal to the sum of the height values of the first fixing ring (20) and the second fixing ring (21).

2. The indirect hot blast stove for regulating temperature with circulating air according to claim 1, characterized in that: The hot air box (1) and the plate heat exchanger (6) are distributed front and back. The second connecting pipe (24) and the first connecting pipe (5) are distributed left and right between the hot air box (1) and the plate heat exchanger (6). A smoke outlet (2) is fixedly installed on the top of the hot air box (1). The second connecting pipe (24) is communicated with the centrifugal fan (12). The mixer (15) is communicated with the first connecting pipe (5).

3. The indirect hot blast stove for adjusting temperature with circulating air according to claim 1, characterized in that: The left end of the fire protection cylinder (13) is communicated with the inner cavity of the mixing box (14). The left end of the fire protection cylinder (13) is communicated with the inner cavity of the hot air box (1).

4. An indirect hot blast stove for regulating temperature with circulating air according to claim 1, characterized in that: Both the first heat exchange plate (17) and the second heat exchange plate (18) are made by stamping aluminum metal. The horizontal cross-sectional shapes of both the first heat exchange plate (17) and the second heat exchange plate (18) are "U" shaped.

5. An indirect hot blast stove for regulating temperature with circulating air according to claim 1, characterized in that: The same gaps are left between the upper and lower sides of the mixer (15) and the upper and lower sides of the inner wall of the hot air box (1).

6. The indirect hot blast stove for regulating temperature with circulating air according to claim 2, wherein: There are flaring mouths on both the left side of the centrifugal fan (12) and the right side of the burner (4). The smoke outlet (2) is directly above the left side of the centrifugal fan (12), and the temperature of the circulating air is 300 degrees.

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