Insulation device

Abstract

To provide a heat retention device that can further suppress the temperature drop of the fluid in the discharge duct of a heat exchanger. [Solution] A heat retention device 10 is provided in the discharge line of a heat exchanger 3 that utilizes the exhaust from a burner 2, and is connected to the discharge port 3a of the heat exchanger 3 and includes a discharge duct 4 that transports the fluid discharged from the discharge port 3a to the point of use, and an electric heater 5 is attached to at least a part of the discharge duct 4, and the electric heater 5 heats the fluid passing through the discharge duct 4.

Description

Technical Field

[0001] The present invention relates to a heat insulation device provided in an exhaust line of a heat exchanger that utilizes the exhaust of a burner.

Background Art

[0002] Conventionally, for the purpose of energy saving, in order to preheat the combustion air and fuel gas of a burner by heat exchange, a dedicated burner as shown in Patent Document 1 is used, or a configuration in which heat exchange is performed between the exhaust gas of a flue and the flue as shown in Patent Document 2, or a configuration in which the furnace atmosphere is heat-exchanged with the exhaust gas of the flue and circulated as shown in Patent Document 3 is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even if the temperature of the fluid in the exhaust duct of the heat exchanger is increased using the above configuration, there is a problem that the temperature decreases due to heat dissipation before reaching the place of use (burner or furnace). Currently, as a countermeasure against this problem, a heat insulating material is arranged around the exhaust duct to suppress the temperature drop of the fluid, but the effect is not sufficient. In addition, since the heat exchanger is designed with heat dissipation in mind, it becomes large, requiring more installation space and increasing the manufacturing cost.

[0005] Therefore, an object of the present invention is to provide a heat insulation device that can further suppress the temperature drop of the fluid in the exhaust duct of the heat exchanger. [Means for solving the problem]

[0006] The present invention relates to a heat retention device installed in the exhaust line of a heat exchanger that utilizes the exhaust from a burner, The heat exchanger is equipped with a discharge duct that is connected to the discharge port and transports the fluid discharged from the discharge port to the point of use. An electric heater is attached to at least a portion of the discharge duct, and the electric heater heats the fluid passing through the discharge duct.

[0007] According to the above configuration, the fluid discharged from the heat exchanger outlet and passing through the discharge duct is heated by an electric heater, thus suppressing the temperature drop of the fluid inside the discharge duct. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a heat retention device that can further suppress the temperature drop of the fluid in the discharge duct of a heat exchanger. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a heat treatment apparatus equipped with a heat retention device according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram of a heat treatment apparatus equipped with a heat retention device according to a second embodiment of the present invention. [Figure 3] This is a schematic diagram of a heat treatment apparatus equipped with a heat retention device according to a third embodiment of the present invention. [Modes for carrying out the invention]

[0010] (First Embodiment) Figure 1 is a schematic diagram of a heat treatment apparatus 90 equipped with a heat retention device 10 according to the first embodiment of the present invention. As shown in Figure 1, the heat treatment apparatus 90 is a heat treatment apparatus that heats and processes an object to be treated, and comprises a furnace 1 in which the object to be treated is placed, a burner 2 for heating the object to be treated, a heat exchanger 3 for exchanging heat between the high-temperature exhaust gas generated by the combustion of the burner 2 and a fluid, and a discharge duct 4 connected to the discharge port 3a of the heat exchanger 3 and transporting the fluid discharged from the discharge port 3a to the burner 2. In this embodiment, the fluid that exchanges heat with the exhaust gas is combustion air supplied to the burner 2.

[0011] Burner 2 includes a fuel pipe 21 to which fuel gas is supplied and a supply pipe 22 to which combustion air is supplied. The fuel pipe 21 is equipped with a control valve 21a for adjusting the amount of fuel gas supplied. The supply pipe 22 is connected to the exhaust duct 4 via a control valve 22a for adjusting the amount of combustion air supplied. In other words, air that has undergone heat exchange with exhaust gas by the heat exchanger 3 passes through the exhaust duct 4 and is supplied to the supply pipe 22 as combustion air via the control valve 22a.

[0012] Burner 2 mixes fuel gas supplied from fuel pipe 21 with combustion air supplied from supply pipe 22 to generate a flame inside furnace 1. The object to be processed (not shown) placed inside furnace 1 is heated by the flame from burner 2.

[0013] An electric heater 5 is attached to at least a portion of the exhaust duct 4, and the electric heater 5 heats the fluid passing through the exhaust duct 4.

[0014] The discharge duct 4 has a plurality of sections, and an electric heater 5 and a temperature sensor 6 are provided as a pair for each section. The output of the electric heater 5 for each section is controlled according to the measurement result of the temperature sensor 6 provided in that section. Specifically, the heat preservation device 10 includes a control device 7 that controls the output of the electric heater 5 according to the discharge duct 4, the electric heater 5, the temperature sensor 6, and the measurement result of the temperature sensor 6. The control device 7 controls the temperature for each section of the discharge duct 4, activates the electric heater 5 for the section with a large temperature drop, and heats the fluid flowing through that section. In this embodiment, although a plurality of electric heaters 5 and one corresponding temperature sensor 6 are provided as a pair for each section, one temperature sensor 6 may be provided for one electric heater 5 in each section, or a plurality of electric heaters 5 may be provided in each section, and one temperature sensor 6 may be provided for each electric heater 5.

[0015] In order to suppress heat dissipation from the discharge duct 4, a heat insulating material 8 may be arranged to cover the discharge duct 4. When the heat insulating material 8 is arranged on the discharge duct 4, the heat insulating material 8 is arranged to also cover the electric heater 5 attached to the discharge duct 4.

[0016] According to the heat preservation device 10 having the above configuration, the following effects can be exerted.

[0017] (1) Since the fluid discharged from the discharge port 3a of the heat exchanger 3 and passing through the discharge duct 4 is heated by the electric heater 5, the temperature drop of the fluid in the discharge duct 4 can be suppressed.

[0018] (2) If the arrangement of the heat insulating material 8 for the discharge duct 4 is reduced or becomes unnecessary due to the heating of the electric heater 5, an increase in the overall shape of the discharge duct 4 can be suppressed, and the arrangement space can be rationalized.

[0019] (3) Since the output of the electric heater 5 is controlled based on the temperature of the fluid by the temperature sensor 6, the amount of electricity used can be rationalized.

[0020] (4) An electric heater 5 and a temperature sensor 6 are respectively arranged in each section of the discharge duct 4, and the electric heater 5 is controlled based on the temperature of the fluid. Therefore, heating can be performed as much as necessary for each section, and the amount of electricity used can be rationalized.

[0021] In the above embodiment, the fluid that exchanges heat with the exhaust gas is the combustion air supplied to the burner 2, and an electric heater 5 is attached to the discharge duct 4 through which the combustion air passes for heating. However, the fuel gas supplied to the burner 2 may be heat-exchanged with the exhaust gas in a heat exchanger, and an electric heater may be attached to the discharge duct through which the fuel gas passes for heating. Also, electric heaters may be attached to both the discharge duct through which the combustion air passes and the discharge duct through which the fuel gas passes to heat those fluids.

[0022] (Second Embodiment) FIG. 2 is a schematic view of a heat treatment apparatus 90 provided with a heat preservation device 10 according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the gas that exchanges heat with the exhaust gas in the heat exchanger 3 is hydrogen gas instead of air, and that hydrogen gas is used as the fuel gas for the burner 2, and other configurations are the same as those of the first embodiment. Therefore, in the description of the second embodiment, the same reference numerals are given to the same parts as those of the first embodiment, and detailed descriptions thereof are omitted.

[0023] The burner 2 includes a fuel pipe 21 to which hydrogen gas is supplied and a supply pipe 22 to which combustion air is supplied. An adjustment valve 22a for adjusting the supply amount of the combustion air is provided in the supply pipe 22. The fuel pipe 21 is connected to the discharge duct 4 via an adjustment valve 21a for adjusting the supply amount of the hydrogen gas. That is, the hydrogen gas that has exchanged heat with the exhaust gas by the heat exchanger 3 passes through the discharge duct 4 and is supplied as fuel gas to the fuel pipe 21 via the adjustment valve 22a.

[0024] Burner 2 mixes hydrogen gas supplied from fuel pipe 21 with combustion air supplied from supply pipe 22 to generate a flame inside furnace 1. The object to be processed (not shown) placed inside furnace 1 is heated by the flame from burner 2.

[0025] An electric heater 5 is attached to at least a portion of the exhaust duct 4, and the electric heater 5 heats the hydrogen gas passing through the exhaust duct 4.

[0026] The exhaust duct 4 has multiple sections, and an electric heater 5 and a temperature sensor 6 are provided in each section. The output of the electric heater 5 in each section is controlled by the measurement results of the temperature sensor 6 installed in that section. Specifically, the heating device 10 includes the exhaust duct 4, the electric heater 5, the temperature sensor 6, and a control device 7 that controls the output of the electric heater 5 based on the measurement results of the temperature sensor 6. The control device 7 controls the temperature in each section of the exhaust duct 4 and activates the electric heater 5 in the section where the temperature drop is large, heating the hydrogen gas flowing through that section.

[0027] Hydrogen gas has high thermal conductivity, and a temperature drop is likely to occur when it passes through the exhaust duct. However, according to the above embodiment, the hydrogen gas can be effectively heated by heating it with the electric heater 5, and the heat retention device 10 can be applied to the burner 2 or furnace that uses hydrogen gas.

[0028] Furthermore, the heating device 10 can also be applied when a hydrocarbon gas is used as the fuel gas instead of hydrogen gas. In this case, when a hydrocarbon gas is used as the fuel gas, an upper temperature limit is set in each section that gradually increases toward the downstream side to prevent the hydrocarbon gas from decomposing due to overheating (even in the most downstream section, a temperature below the decomposition temperature of the gas is set). In addition to the measurement results of the temperature sensor 6 installed in that section, the output of the electric heater 5 is controlled so as not to exceed the set upper temperature limit.

[0029] In the above embodiment, the fluid that exchanges heat with the exhaust gas is hydrogen gas supplied to the burner 2, and an electric heater 5 is installed in the exhaust duct 4 through which the hydrogen gas passes to heat it. However, the combustion air supplied to the burner 2 may also be heat-exchanged with the exhaust gas in a heat exchanger, and an electric heater may be installed in the exhaust duct through which the combustion air passes to heat it. Alternatively, electric heaters may be installed in both the exhaust duct through which the hydrogen gas passes and the exhaust duct through which the combustion air passes to heat those fluids.

[0030] (Third embodiment) Figure 3 is a schematic diagram of a heat treatment apparatus 90 equipped with a heat retention device 10 according to the third embodiment of the present invention. The third embodiment differs from the first embodiment in that the gas that exchanges heat with the exhaust gas in the heat exchanger 3 is a combustion-supporting gas, such as oxygen gas, and that this oxygen gas is introduced into the furnace. The other configurations are the same as those of the first embodiment. For this reason, in the description of the third embodiment, the same reference numerals are used for the same parts as in the first embodiment, and detailed explanations of their contents are omitted. Note that the combustion-supporting gas that exchanges heat with the exhaust gas and is introduced into the furnace is not limited to oxygen gas.

[0031] Burner 2 includes a fuel pipe 21 to which fuel gas is supplied, and a supply pipe 22 to which combustion air is supplied. The fuel pipe 21 is equipped with a control valve 21a for adjusting the amount of fuel gas supplied. The supply pipe 22 is equipped with a control valve 22a for adjusting the amount of combustion air supplied.

[0032] Burner 2 mixes fuel gas supplied from fuel pipe 21 with combustion air supplied from supply pipe 22 to generate a flame inside furnace 1. The object to be processed (not shown) placed inside furnace 1 is heated by the flame from burner 2.

[0033] The combustion gas of the exhaust gas generated in the furnace 1 by the combustion of burner 2 is heat-exchanged with oxygen gas in heat exchanger 3, and the oxygen gas heated by the exhaust gas is introduced into the furnace 1 through exhaust duct 4.

[0034] The exhaust duct 4 has multiple sections, and an electric heater 5 and a temperature sensor 6 are provided in each section. The output of the electric heater 5 in each section is controlled by the measurement results of the temperature sensor 6 installed in that section. Specifically, the heating device 10 includes the exhaust duct 4, the electric heater 5, the temperature sensor 6, and a control device 7 that controls the output of the electric heater 5 based on the measurement results of the temperature sensor 6. The control device 7 controls the temperature in each section of the exhaust duct 4 and activates the electric heater 5 in the section where the temperature drop is large, heating the oxygen gas flowing through that section.

[0035] The oxygen gas heated by the electric heater 5 is introduced into the furnace 1 so that it reaches the inlet 9 near the combustion section of the burner 2, thereby improving the combustion efficiency of the burner 2.

[0036] According to the above embodiment, since the heat exchanger 3 exchanges heat with the exhaust gas and the resulting high-temperature oxygen gas is introduced into the furnace, the combustion of the burner 2 can be promoted.

[0037] In the above embodiment, the fluid that exchanges heat with the exhaust gas is oxygen gas introduced into the furnace 1, and an electric heater 5 is installed in the exhaust duct 4 through which the oxygen gas passes to heat it. However, fuel gas or combustion air supplied to the burner 2 may also be heat-exchanged with the exhaust gas in the heat exchanger, and electric heaters may be installed in the exhaust duct through which the fuel gas passes and the exhaust duct through which the combustion air passes to heat them. Alternatively, electric heaters may be installed in any of the exhaust ducts through which the oxygen gas introduced into the furnace passes, the exhaust duct through which the combustion air passes, and the exhaust duct through which the fuel gas passes to heat these fluids.

[0038] The present invention and its embodiments are summarized as follows.

[0039] (1) One embodiment of the present invention is a heat retention device installed in the exhaust line of a heat exchanger that utilizes the exhaust from a burner, The heat exchanger is equipped with a discharge duct that is connected to the discharge port and transports the fluid discharged from the discharge port to the point of use. An electric heater is attached to at least a portion of the discharge duct, and the electric heater heats the fluid passing through the discharge duct.

[0040] According to the above configuration (1), the fluid discharged from the heat exchanger outlet and passing through the discharge duct is heated by an electric heater, thus suppressing the temperature drop of the fluid inside the discharge duct. Furthermore, if the amount of insulation material required is reduced or eliminated due to heating by the electric heater, the overall size of the discharge duct can be suppressed, and the installation space can be rationalized.

[0041] (2) In the above configuration (1), the discharge duct is provided with a temperature sensor for measuring the temperature of the fluid passing through the discharge duct. The output of the electric heater is controlled based on the measurement results from the temperature sensor.

[0042] According to the above configuration (2), the output of the electric heater is controlled based on the temperature of the fluid, so the amount of electricity used can be rationalized.

[0043] (3) In the above configuration (2), the electric heater and the temperature sensor are provided as a pair, The pair of electric heaters and the temperature sensor are respectively placed in each section of the exhaust duct.

[0044] According to the above configuration (3), electric heaters and temperature sensors are placed in each section of the discharge duct, and the electric heaters are controlled based on the fluid temperature, so that only the necessary amount of heating can be done in each section, and the amount of electricity used can be rationalized.

[0045] (4) In any one of the above configurations (1) to (3), the fluid passing through the discharge duct is hydrogen gas.

[0046] Hydrogen gas has high thermal conductivity, and a temperature drop is likely to occur when it passes through the exhaust duct. However, according to the above configuration (4), the hydrogen gas can be effectively heated by heating it with an electric heater, and this can be applied to burners and furnaces that use hydrogen gas.

[0047] (5) In the above configuration (4), the hydrogen gas is used as the fuel gas for the burner.

[0048] According to the above configuration (5), it can be applied to a hydrogen gas burner that uses hydrogen gas as a fuel gas.

[0049] (6) In any one of the above configurations (1) to (3), the fluid passing through the discharge duct is a combustion-supporting gas and is introduced into the furnace atmosphere of the burner furnace using the burner.

[0050] According to the above configuration (6), the combustion-supporting gas, which has been heated through heat exchange with the burner's exhaust, is introduced into the furnace, thereby promoting combustion in the burner.

[0051] Various modifications and alterations can be made without departing from the spirit and scope of the invention as described in the claims. [Industrial applicability]

[0052] The present invention provides a heat retention device that can further suppress the temperature drop of the fluid in the discharge duct of a heat exchanger, and therefore has great industrial value. [Explanation of Symbols]

[0053] 1 furnace 2 burners 21 Fuel pipe 21a Control valve 22 Supply pipe 22a Control valve 3 Heat exchanger 3a Outlet 4. Exhaust duct 5 Electric heater 6. Temperature sensor 7 Control device 8 Heat insulation material 9 Inlet 10 Heat retention device 90 Heat treatment equipment

Claims

1. A heat retention device installed on the discharge side of a heat exchanger that utilizes the exhaust from a burner, The heat exchanger is equipped with a discharge duct that is connected to the discharge port and transports the fluid discharged from the discharge port to the point of use. An electric heater is attached to at least a portion of the discharge duct, and the electric heater heats the fluid passing through the discharge duct. The aforementioned exhaust duct is fitted with insulating material so as to cover the exhaust duct. The aforementioned heat-insulating material covers the electric heater which is attached to the exhaust duct. The aforementioned discharge duct is equipped with a temperature sensor that measures the temperature of the fluid passing through the discharge duct. A heat retention device that controls the output of the electric heater so that the measurement result of the temperature sensor does not exceed the upper temperature limit.

2. The electric heater and the temperature sensor are provided as a pair. The heating device according to claim 1, wherein a pair of electric heaters and temperature sensors are respectively arranged in each section of the exhaust duct.

3. The heat retention device according to claim 1 or 2, wherein the fluid passing through the discharge duct is hydrogen gas.

4. The heating device according to claim 3, wherein the hydrogen gas is used as the fuel gas for the burner.

5. The heat retention device according to claim 1 or 2, wherein the fluid passing through the discharge duct is a combustion-supporting gas and is introduced into the furnace atmosphere of a burner furnace using the burner.

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