JP2016166683A - Heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device capable of reducing a use amount of fuel by improving fuel economy.SOLUTION: A heating device 30 includes a burner 31 for jetting a combustion gas 20 in which a fuel 22 is burned toward a combustion space 3 of a heating furnace 1, and discharges an exhaust gas 26 after heating the combustion space 3 from an exhaust gas discharge passage 36. A first heat exchanger 31a disposed in the exhaust gas discharge passage 36 is incorporated in the burner 31, and a second heat exchanger 38 is disposed in the exhaust gas discharge passage 36 on the further downstream than the first heat exchanger 31a. Air 24 for combustion mixed in the fuel 22 in combustion is supplied to the burner 31 from an air passage 34, and the second heat exchanger 38 is disposed on the upstream side of the air passage 34 and the first heat exchanger 31a is disposed on the downstream side of the air passage 34 respectively. Heat is imparted to the low-temperature air 24 for combustion from the high-temperature exhaust gas 26 by comparing with each other by the first heat exchanger 31a and the second heat exchanger 38, so that fuel economy is improved and the use amount of the fuel 22 can be reduced.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a heating device, and more particularly to a heating device that can improve fuel efficiency and reduce the amount of fuel used.

  Conventionally, as a heating apparatus for heating a combustion space of a heating furnace, an apparatus in which the heat of exhaust gas is recovered and applied to combustion air to reduce the amount of gas used and improve fuel efficiency is known. . For example, there is one in which a heat exchanger that gives heat of exhaust gas to combustion air is built in a burner to improve fuel consumption while suppressing an increase in size of a heating device (Patent Document 1).

Japanese Patent No. 5581422

  However, in the case of a heating device in which a heat exchanger is disposed on the burner or the furnace wall, the heat of the exhaust gas is difficult to be radiated to the outside inside the burner or the furnace wall that becomes high temperature due to the combustion of fuel. It is necessary to use a material having a high exhaust gas temperature and a high heat-resistant temperature for the heat exchanger. For example, silicon carbide having a high heat-resistant temperature and high thermal conductivity can be given. Since silicon carbide is difficult to process, it is difficult to increase the heat transfer area by devising the shape of the heat exchanger in order to improve the heat exchange rate. That is, in a heating device in which a heat exchanger is provided on a burner or a furnace wall, the heat exchange rate is limited, and it is difficult to improve fuel consumption.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a heating device that can improve fuel efficiency and reduce the amount of fuel used.

Means for Solving the Problems and Effects of the Invention

  According to the heating device of the first aspect, the combustion apparatus includes a burner that ejects combustion gas obtained by burning the fuel supplied through the fuel passage toward the combustion space surrounded by the furnace wall of the heating furnace, The heated exhaust gas is discharged from the exhaust gas discharge passage. A first heat exchanger is disposed in the exhaust gas discharge path and the burner or the furnace wall, and a second heat exchanger is disposed in the exhaust gas discharge path downstream from the first heat exchanger. Combustion air mixed with fuel when the fuel is burned is supplied from the air passage to the burner. The second heat exchanger is arranged upstream of the air passage, and the first heat exchanger is arranged downstream of the air passage. Established. Since heat exchange is performed by the first heat exchanger and the second heat exchanger between the exhaust gas passing through the exhaust gas discharge passage and the combustion air passing through the air passage, the temperature of the exhaust gas is lower than that of the hot exhaust gas. Heat is applied to the combustion air. Since the combustion air is heated by the two-stage heat exchange, there is an effect that the fuel consumption can be improved and the amount of fuel used can be reduced.

  Also, compared with the upstream side and the downstream side of each of the air passage and the exhaust gas discharge passage, heat exchange is performed by the first heat exchanger between the high-temperature combustion air and the high-temperature exhaust gas, Heat is exchanged between the combustion air and the low-temperature exhaust gas by the second heat exchanger. Since the temperature difference between the combustion air and the exhaust gas in the first heat exchanger and the second heat exchanger can be reduced, the durability of the first heat exchanger and the second heat exchanger can be improved.

  According to the heating device of the second aspect, the first heat exchanger and the second heat exchanger are compared with each other, and the first heat exchanger has a high heat-resistant temperature and a low heat exchange rate. The exchanger has a low heat-resistant temperature and a high heat exchange rate. Since the heat of the exhaust gas is hardly radiated to the outside inside the burner or the furnace wall that becomes high temperature due to the combustion of fuel, the temperature of the exhaust gas passing through the first heat exchanger disposed on the burner or the furnace wall is high. The durability of the first heat exchanger can be ensured by disposing the first heat exchanger having a high heat resistance temperature on the burner or the furnace wall.

  Furthermore, since the heat-resistant temperature of the second heat exchanger through which the exhaust gas deprived of heat by the first heat exchanger passes can be lowered, the degree of freedom of the structure and material of the second heat exchanger can be increased. Since the heat exchange rate can be improved by devising the structure and shape of the second heat exchanger, in addition to the effect of claim 1, there is an effect that the fuel consumption can be improved and the amount of fuel used can be further reduced.

According to the heating device of the third aspect, the temperature of the combustion gas is adjusted by mixing a part of the combustion air with the fuel through the connecting passage that connects the air passage upstream of the second heat exchanger and the fuel passage. it is possible to reduce the NO _X down. When the air path downstream of the second heat exchanger and the fuel path are connected, the combustion air and the fuel heated by the heat exchange by the second heat exchanger are mixed, and the fuel may ignite. There is. By connecting the air passage upstream of the second heat exchanger and the fuel passage by the connection passage, it is possible to prevent the fuel from being ignited when a part of the combustion air is mixed with the fuel. Therefore, in addition to the effect of the first or second aspect, there is an effect that NO _X can be reduced while preventing ignition when a part of the combustion air is mixed with the fuel.

  According to the heating device of the fourth aspect, the exhaust gas discharge path includes an opening for discharging the exhaust gas to the outside, and the opening side of the exhaust gas discharge path is inclined downward. As a result of taking heat from the exhaust gas by the two heat exchangers, the temperature of the exhaust gas discharged from the opening may be lower than the dew point temperature. In that case, there is a possibility that condensation occurs on the opening side of the exhaust gas discharge path due to moisture in the exhaust gas. Since the dew condensation moisture can be positively collected by the downward inclination of the opening side of the exhaust gas discharge path, in addition to the effect of any one of claims 1 to 3, the dew condensation water can be prevented from flowing back through the exhaust gas discharge path. effective.

  According to the heating device of claim 5, the temperature of the exhaust gas at the inlet of the first heat exchanger in the exhaust gas discharge path is detected by the first temperature sensor, and the exhaust gas at the inlet of the second heat exchanger in the exhaust gas discharge path. Is detected by the second temperature sensor, and the supply amounts of the fuel and the combustion air are feedback-controlled by the control device based on the temperatures detected by the first temperature sensor and the second temperature sensor. As a result, the amount of combustion can be adjusted so as not to exceed the heat resistance temperature of the first heat exchanger and the second heat exchanger. In addition to the effects of claims 1 to 4, the first heat exchanger and the second heat exchanger There is an effect that can ensure the durability.

It is a top view of the heating furnace in embodiment of this invention. It is sectional drawing of the heating furnace in the II-II line of FIG. It is sectional drawing of the heating furnace in the III-III line of FIG. It is the side view of the heating apparatus seen from the arrow IV direction of FIG. It is sectional drawing of the burner in the VV line | wire of FIG. (A) is the block diagram which showed the electrical structure of the control apparatus, (b) is the partial piping figure of an air path and a fuel path.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. First, the heating furnace 1 will be described with reference to FIGS. 1, 2, and 3. 1 is a plan view of a heating furnace 1 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the heating furnace 1 taken along line II-II in FIG. 1, and FIG. 3 is a line III-III in FIG. It is sectional drawing of the heating furnace 1 in. In FIG. 1, the illustration of the exhaust gas discharge path 36 downstream from the second heat exchanger 38 is omitted, and in FIG. 1 and FIG. 3, the burner 31 inside the heating furnace 1 is shown by a broken line. In FIG. 2, the flow direction of the combustion gas 20 is a two-dot chain line, the flow direction of the fuel 22 is a two-dot chain arrow, and the flow direction of the combustion air 24 is a solid line arrow. The flow direction of the exhaust gas 26 is indicated by a solid white arrow (the same applies to FIGS. 4 and 5).

  As shown in FIGS. 1 and 2, the heating furnace 1 includes a substantially cylindrical furnace wall 2 made of a ceramic fiber refractory and closed at the lower end, and a substantially columnar shape surrounded by the furnace wall 2. A heating device 30 having a crucible 4 arranged in alignment with the central axis of the combustion space 3, a furnace lid 5 that closes the upper end of the furnace wall 2, and a burner 31 that ejects the combustion gas 20 from the tip toward the combustion space 3. And. The crucible 4 is disposed on a crucible base 6 disposed in the center of the combustion space 3.

  The furnace wall 2 is formed by joining three fan-shaped portions and one square-shaped portion in plan view. Since the furnace wall 2 can be manufactured by manufacturing the fan-shaped part and the square-shaped part and then joining them together, the furnace wall 2 can be easily manufactured. Note that three fan-shaped portions and one square-shaped portion may be integrally formed.

  The furnace wall 2 is attached to the lower end side of the square-shaped portion with the burner 31 facing the front end in a direction perpendicular to the outer wall surface of the square-shaped portion, so that the combustion gas 20 ejected from the burner 31 is inside the furnace wall 2. It rises spirally along the circumference. The object to be heated in the crucible 4 is heated by heating the combustion space 3 while the combustion gas 20 rises spirally. The combustion gas 20 is generated by mixing the combustion air 24 with the fuel 22 which is a gaseous fuel and igniting and burning it by the ignition device 31b (see FIG. 5) of the burner 31. After the combustion space 3 is heated, the combustion gas 20 is exhausted. It becomes gas 26.

  As shown in FIGS. 2 and 3, the heating furnace 1 includes a plurality of first exhaust gas passages 10 arranged at equal intervals in the circumferential direction of the furnace wall 2 from the upper end side of the combustion space 3 toward the radially outer side of the furnace wall 2. A second exhaust gas passage 12 that is connected to the plurality of first exhaust gas passages 10 and is formed in the furnace wall 2 in a plan view, and a third gas exhaust gas that is formed in the furnace wall 2 downward from the second exhaust gas passage 12. An exhaust gas hole 31 c (see FIG. 5) provided in the burner 31 is provided in the third exhaust gas channel 14. The exhaust gas 26 flows into the exhaust gas hole 31c from the combustion space 3 through the first exhaust gas passage 10, the second exhaust gas passage 12, and the third exhaust gas passage 14 in this order.

  Since the plurality of first exhaust gas passages 10 are arranged at equal intervals in the circumferential direction of the furnace wall 2, the temperatures of the furnace wall 2, the combustion space 3 and the crucible 4 can be kept uniform in the circumferential direction. Since the second exhaust gas passage 12 extends downward from the plurality of first exhaust gas passages 10, as compared with the case where the second exhaust gas passage 12 extends from the first exhaust gas passage 10 to the side. Thus, the heating furnace 1 can be prevented from being enlarged.

  Since the second exhaust gas passage 12 is formed to have a larger flow passage cross-sectional area than the flow passage cross-sectional area of the first exhaust gas passage 10, the wind speed of the exhaust gas 26 in the second exhaust gas passage 12 than the first exhaust gas passage 10. Can be lowered. The flow path cross-sectional area is the area of the flow path orthogonal to the flow path direction, and the flow path cross-sectional area of the first exhaust gas path 10 is the area of the circumferential cross section. The area is the area of the radial cross section.

  The position where the third exhaust gas path 14 is connected to the second exhaust gas path 12 is located between the plurality of first exhaust gas paths 10 in the circumferential direction of the furnace wall 2. When the connection position between the second exhaust gas path 12 and the third exhaust gas path 14 is the position of the first exhaust gas path 10 in the circumferential direction of the furnace wall 2, the connection between the second exhaust gas path 12 and the third exhaust gas path 14. The exhaust gas 26 passing through the first exhaust gas passage 10 located at the position predominantly flows into the third exhaust gas passage 14. That is, it becomes difficult for the exhaust gas 26 to flow into the third exhaust gas passage 14 from the other first exhaust gas passages 10 through the second exhaust gas passage 12, and the furnace wall 2, the combustion space 3, and a part of the crucible 4 become high temperature. There is a fear. Since the connection position of the second exhaust gas path 12 and the third exhaust gas path 14 is located between the plurality of first exhaust gas paths 10 in the circumferential direction of the furnace wall 2, one of the furnace wall 2, the combustion space 3, and the crucible 4 The portion can be prevented from becoming hot.

  Next, the heating device 30 will be described with reference to FIGS. 4 and 5. 4 is a side view of the heating device 30 as viewed from the direction of arrow IV in FIG. 2, and FIG. 5 is a cross-sectional view of the burner 31 taken along the line V-V in FIG.

  As shown in FIG. 4, the heating device 30 includes a burner 31 containing a first heat exchanger 31 a (see FIG. 5), a fuel passage 32 that supplies fuel 22 to the burner 31, and combustion air 24 to the burner 31. An air passage 34 for supplying exhaust gas, an exhaust gas exhaust passage 36 for exhausting exhaust gas 26, an air passage 34 upstream from the burner 31 (first heat exchanger 31a), and a burner 31 (first heat exchanger 31a). And a second heat exchanger 38 disposed in the downstream exhaust gas discharge path 36. The first heat exchanger 31 a and the second heat exchanger 38 are devices for performing heat exchange between the combustion air 24 passing through the air passage 34 and the exhaust gas 26 passing through the exhaust gas discharge passage 36.

  As shown in FIG. 5, the burner 31 has a fuel path 32, an air path 34, and an exhaust gas discharge path 36 extending on the inner side. And are supplied. An exhaust gas hole 31 c that opens to the third exhaust gas passage 14 is provided on the tip side of the burner 31, and the exhaust gas 26 flows into the exhaust gas exhaust passage 36 from the exhaust gas hole 31 c. The first heat exchanger 31a built in the burner 31 is a cylindrical wall that separates the air passage 34 and the exhaust gas discharge passage 36, and is a parallel flow heat exchanger made of silicon carbide.

  Returning to FIG. The second heat exchanger 38 is an orthogonal heat exchanger formed by laminating stainless steel plates. The fuel path 32 is connected to the air path 34 upstream of the second heat exchanger 38 via a connection path 39, and a part of the combustion air 24 is mixed with the fuel 32 through the connection path 39.

  Since the air passage 34 is formed with a larger cross-sectional area toward the inlet and outlet of the second heat exchanger 38, the air passage 34 has a size while ensuring the wind speed of the air passage 34 upstream and downstream of the second heat exchanger. A large second heat exchanger 38 can be used. Since the wind speed of the combustion gas 20 can be secured and the heat transfer area of the second heat exchanger 38 can be increased, the heat transfer rate from the combustion gas 20 to the combustion space 3 can be secured and the heat exchange rate of the second heat exchanger 38 can be secured. Can be improved.

  The exhaust gas discharge path 36 includes an opening 37 for discharging the exhaust gas 26 to the outside, and the opening 37 side is inclined downward (see FIG. 2). The exhaust gas discharge path 36 has a flow passage cross-sectional area that increases toward the inlet of the second heat exchanger 38 and has a cross-sectional area downstream of the second heat exchanger 38 as compared with the upstream side of the second heat exchanger 38. Largely formed. Therefore, the wind speed of the exhaust gas 26 discharged to the outside from the opening 37 can be reduced.

  The first heat exchanger 31a made of silicon carbide has a heat resistant temperature of about 1200 ° C., and the second heat exchanger 38 made of stainless steel has a heat resistant temperature of about 750 ° C. The heating device 30 detects the temperature of the exhaust gas 26 so as not to exceed the heat resistance temperature of the first heat exchanger 31a and the second heat exchanger 38, and the control device 50 controls the supply amount of the fuel 22 and the combustion air 24. The amount of combustion is adjusted to adjust.

  Next, a method for controlling the heating device 30 will be described with reference to FIGS. 6 (a) and 6 (b). FIG. 6A is a block diagram showing an electrical configuration of the control device 50, and FIG. 6B is a partial piping diagram of the air passage 34 and the fuel passage 32.

  As shown in FIG. 6A, the control device 50 includes a CPU 51, a ROM 52, and a RAM 53, which are connected to an input / output port 55 via a bus line 54. The input / output port 55 is connected to a first temperature sensor 61, a second temperature sensor 62, a blower 63 and an electromagnetic valve 64.

  The CPU 51 is an arithmetic unit that controls each unit connected by the bus line 54. The ROM 52 is a non-rewritable nonvolatile memory that stores a control program executed by the CPU 51, fixed value data, and the like. The RAM 53 is a memory for storing various data in a rewritable manner when the control program is executed.

  The first temperature sensor 61 is a sensor for detecting the temperature of the exhaust gas 26 at the inlet of the first heat exchanger 31 a in the exhaust gas discharge path 36, and an output circuit (not shown) that processes the detection result and transmits it to the CPU 51. )). The second temperature sensor 62 is a sensor for detecting the temperature of the exhaust gas 26 at the inlet of the second heat exchanger 38 in the exhaust gas discharge path 36, and an output circuit (not shown) that processes the detection result and transmits it to the CPU 51. )).

  As shown in FIG. 6B, the blower 63 is a device for supplying the combustion air 24 to the air passage 34 by driving the motor, and the motor is driven and controlled based on an instruction from the CPU 51. Thus, the supply amount of the combustion air 24 is adjusted. The electromagnetic valve 64 is a device that is disposed in the fuel path 32 and opens the valve when an electric current is passed, so that the fuel 22 can be supplied. The valve is opened and closed based on an instruction from the CPU 51.

  The main plug 65 is disposed in the fuel passage 32 upstream from the electromagnetic valve 64, and allows the fuel 22 to be supplied by manually opening and closing. The pressure equalizing valve 66 is disposed in the fuel passage 32 downstream of the electromagnetic valve 64, and the valve is opened and closed so that the pressure of the combustion air 24 in the air passage 34 and the pressure of the fuel 22 in the fuel passage 32 are substantially uniform. This is a device for adjusting the supply amount of the fuel 22 by adjusting.

  The control device 50 performs feedback control (PID control) of the supply amount of the combustion air 24 and the supply amount of the fuel 22 via the pressure equalizing valve 66 based on the temperatures detected by the first temperature sensor 61 and the second temperature sensor 62. ) As a result, the combustion amount can be adjusted so as not to exceed the heat resistance temperature of the first heat exchanger 31a and the second heat exchanger 38, so that the durability of the first heat exchanger 31a and the second heat exchanger 38 can be ensured. . When stopping the supply of fuel 22, the control device 50 controls the electromagnetic valve 64 to close the valve. In addition to the feedback control based on the detection results of the first temperature sensor 61 and the second temperature sensor 62, the control device 50 controls the combustion air 24 and the fuel 22 so that the combustion space 3 has a desired set temperature. The supply amount is controlled.

  According to the heating device 30, heat is applied from the exhaust gas 26 to the combustion air 24 by the first heat exchanger 31 a and the second heat exchanger 38, that is, the combustion air 24 is converted into two stages of heat exchange. Since it is heated, the fuel consumption can be improved and the amount of fuel 22 used can be reduced. The first heat exchanger is disposed on the downstream side of the air passage 34 and the upstream side of the exhaust gas discharge passage 36, and the second heat exchanger is disposed on the upstream side of the air passage 34 and the downstream side of the exhaust gas discharge passage 36. Therefore, the upstream side and the downstream side of each of the air passage 34 and the exhaust gas discharge passage 36 are compared with each other by the first heat exchanger 31a between the high-temperature combustion air 24 and the high-temperature exhaust gas 26. Heat exchange is performed, and heat exchange is performed between the low-temperature combustion air 24 and the low-temperature exhaust gas 26 by the second heat exchanger 38. Thereby, since the temperature difference between the combustion air 24 and the exhaust gas 26 in the first heat exchanger 31a and the second heat exchanger 38 can be reduced, the durability of the first heat exchanger 31a and the second heat exchanger 38 is improved. Can be improved.

  Moreover, compared with each other, the first heat exchanger 31a made of silicon carbide has a high heat resistant temperature, and the second heat exchanger 38 made of stainless steel has a low heat resistant temperature. Since the heat of the exhaust gas 26 passing through the inside of the burner 31 that becomes high temperature due to the combustion of the fuel 22 is difficult to dissipate to the outside, the temperature of the exhaust gas 26 passing through the first heat exchanger 31a built in the burner 31 is high. Since the 1st heat exchanger 31a with high heat-resistant temperature is incorporated in the burner 31, durability of the 1st heat exchanger 31a is securable. Furthermore, since the heat resistant temperature of the second heat exchanger 38 through which the exhaust gas 26 deprived of heat by the first heat exchanger 31a can be lowered, the degree of freedom of the structure and material of the second heat exchanger 38 can be increased. The second heat exchanger 38 can be made of a material having a high thermal conductivity, and the shape and structure of the second heat exchanger 38 can be devised to improve the heat exchange rate, so that the first heat exchanger 31a and In comparison, the heat exchange rate of the second heat exchanger 38 can be increased. Thereby, a fuel consumption can be improved and the usage-amount of the fuel 22 can be reduced more.

Further, the temperature of the combustion gas 20 is lowered by premixing a part of the combustion air 24 with the fuel 22 through a connecting passage 39 that connects the air passage 34 upstream of the second heat exchanger 38 and the fuel passage 32. it is possible to reduce the NO _X Te. On the other hand, when the air passage 34 and the fuel passage 32 downstream from the second heat exchanger 38 are connected, the combustion air 24 heated by the second heat exchanger 38 and the fuel 22 are mixed, so that the fuel 22 There is a risk of fire. By connecting the air passage 34 upstream of the second heat exchanger 38 and the fuel passage 32 by the connection passage 39, the fuel 22 is prevented from igniting when a part of the combustion air 24 is mixed with the fuel 22. it is possible to reduce the NO _X while.

  Further, as a result of depriving the heat of the exhaust gas 26 by the first heat exchanger 31a and the second heat exchanger 38, the temperature of the exhaust gas 26 discharged to the outside from the opening 37 of the exhaust gas discharge path 36 is dew point temperature (for example 100 ° C). In that case, moisture in the exhaust gas 26 may cause condensation on the opening 37 side of the exhaust gas discharge path 36. Since the opening 37 side of the exhaust gas discharge path 36 is inclined downward, the condensed moisture can be actively collected. Therefore, it is possible to suppress the condensed water from flowing back through the exhaust gas discharge path 36.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed. For example, in the above embodiment, the case where the fuel 22 is a gaseous fuel has been described. However, the present invention is not necessarily limited to this, and it is naturally possible to employ a liquid fuel as the fuel 22.

  In the above embodiment, the case where the furnace wall 2 is made of a refractory made of ceramic fiber has been described. However, the present invention is not necessarily limited to this, and other refractories can naturally be used for the furnace wall 2. is there. Examples thereof include ceramics such as alumina, bricks, and concrete.

  In the above-described embodiment, the first heat exchanger 31a is a co-current type heat exchanger composed of cylindrical silicon carbide, and the second heat exchanger 38 is formed by stacking stainless steel plates. However, the present invention is not necessarily limited to this, and the structure and material can be appropriately changed so as to satisfy a desired heat-resistant temperature. For example, a counter-flow type heat exchanger and a heat exchanger that periodically switches the flow path to store and release heat can be used. At this time, the first heat exchanger 31a and the second heat exchanger 38 are compared with each other as long as the heat-resistant temperature of the first heat exchanger 31a is high and the heat exchange rate of the second heat exchanger 38 is high. .

  In the above embodiment, the case where the first heat exchanger 31a is built into the burner 31 (disposed inside) and the exhaust gas discharge path 36 is provided inside the burner 31 has been described, but the present invention is not necessarily limited thereto. Of course, it is possible to arrange the first heat exchanger 31 a outside the burner 31. It is also possible to dispose the exhaust gas discharge path 36 and the first heat exchanger 31 a on the furnace wall 2. Since the heat of the exhaust gas 26 is easily radiated to the outside in the exhaust gas exhaust path 36 outside the burner 31 or the furnace wall 2, the exhaust gas 26 is downstream in the exhaust gas exhaust path 36 outside the burner 31 or the furnace wall 2. The temperature is easy to fall. The first heat exchanger 31a is disposed upstream of the exhaust gas exhaust path 36 inside the burner 31 or the furnace wall 2 and the exhaust gas exhaust path 36 outside the burner 31 or the furnace wall 2, that is, the burner 31 or the furnace. By disposing the first heat exchanger 31a on the wall 2, it is possible to suppress the heat of the exhaust gas 26 from being radiated to the outside and improve the fuel efficiency.

  In the above-described embodiment, the case where the condensed moisture is actively collected by descending and tilting the opening 37 side of the exhaust gas discharge passage 36 is not necessarily limited to this, but the opening of the exhaust gas discharge passage 36 is not necessarily limited thereto. It is also possible to provide a hygroscopic material on the inner peripheral surface on the part 37 side to suppress the backflow of condensed moisture.

  In the above-described embodiment, the case where the control device 50 controls the supply amount of the fuel 22 via the pressure equalizing valve 66 has been described. However, the present invention is not necessarily limited to this. Of course, a valve capable of adjusting the supply amount may be provided instead of the pressure equalizing valve 66.

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Furnace wall 3 Combustion space 20 Combustion gas 22 Fuel 24 Combustion air 26 Exhaust gas 30 Heating device 31 Burner 31a 1st heat exchanger 32 Fuel path 34 Air path 36 Exhaust gas discharge path 37 Opening part 38 2nd heat exchange 39 Connection 50 Control device 61 First temperature sensor 62 Second temperature sensor

Claims (5)

A burner for injecting combustion gas obtained by burning fuel supplied through a fuel path toward a combustion space surrounded by a furnace wall of a heating furnace;
An exhaust gas exhaust passage for exhausting exhaust gas after heating the combustion space;
The exhaust gas discharge path, and a first heat exchanger disposed on the burner or the furnace wall;
A second heat exchanger disposed in the exhaust gas discharge path downstream from the first heat exchanger;
The heating apparatus, wherein the second heat exchanger is provided on the upstream side, and the first heat exchanger is provided on the downstream side, and an air passage for supplying combustion air to the burner.   2. The heating apparatus according to claim 1, wherein the second heat exchanger has a lower heat-resistant temperature and a higher heat exchange rate than the first heat exchanger.   The said air path upstream from a said 2nd heat exchanger and the said fuel path are connected, The connection path which mixes a part of said combustion air with the said fuel is provided. The heating device according to 1. The exhaust gas discharge path includes an opening for discharging the exhaust gas to the outside,
The heating apparatus according to any one of claims 1 to 3, wherein the opening side of the exhaust gas discharge path is inclined downward. A first temperature sensor for detecting a temperature of the exhaust gas at an inlet of the first heat exchanger in the exhaust gas discharge path;
A second temperature sensor for detecting the temperature of the exhaust gas at the inlet of the second heat exchanger in the exhaust gas discharge path;
5. The apparatus according to claim 1, further comprising: a control device that feedback-controls a supply amount of the fuel and the combustion air based on temperatures detected by the first temperature sensor and the second temperature sensor. A heating apparatus according to the above.

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