JP2021113645A - Heat recovery system - Google Patents

Abstract

To utilize waste heat with a simple configuration.SOLUTION: A heat recovery system 10 includes: a preheater 1 for heating air; a main heater 2 for heating the air heated by the preheater 1 using steam as a heat source; and a recovery part 3 for recovering drainage discharged from the main heater 2 and supplying heat from the recovered drainage to the preheater 1 as a heat source.SELECTED DRAWING: Figure 1

Description

The techniques disclosed herein relate to heat recovery systems.

Conventionally, a system for recovering exhaust heat from a steam-using device has been known.

For example, the system disclosed in Patent Document 1 recovers waste steam from a steam-using device and recovers heat from the waste steam by using a heat pump. Then, steam is generated by the recovered heat.

Japanese Unexamined Patent Publication No. 2014-95527

However, in the above-mentioned system, a heat pump is required to use the heat recovered from the waste steam for steam generation, and as a result, the system configuration becomes complicated. Therefore, there is a demand for a system that can effectively utilize exhaust heat in a form different from that of a heat pump.

The technology disclosed herein was made in view of this point, and the purpose thereof is to utilize exhaust heat with a simple configuration.

The heat recovery system disclosed herein includes a first heat exchanger that heats a gas, a second heat exchanger that heats the gas heated by the first heat exchanger using steam as a heat source, and the second heat exchange. It is provided with a recovery unit that supplies the heat of the drain discharged from the vessel to the first heat exchanger as a heat source.

According to the heat recovery system, exhaust heat can be utilized with a simple configuration.

FIG. 1 is a schematic piping diagram of the heat recovery system according to the first embodiment. FIG. 2 is a schematic piping diagram of the heat recovery system according to the second embodiment. FIG. 3 is a schematic piping diagram of the heat recovery system according to the third embodiment. FIG. 4 is a schematic piping diagram of the heat recovery system according to the fourth embodiment.

Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

<< Embodiment 1 >>
FIG. 1 is a schematic piping diagram of the heat recovery system 10 according to the first embodiment.

The heat recovery system 10 supplies the preheater 1 that heats the air, the main heater 2 that heats the air heated by the preheater 1 with steam as a heat source, and the heat of the drain discharged from the main heater 2 as a heat source to the preheater 1. It is provided with a collection unit 3 to be used. The heat recovery system 10 recovers the drain discharged from the main heater 2 and supplies the heat contained in the drain to the preheater 1 as a heat source. The preheater 1 is an example of a first heat exchanger, the main heater 2 is an example of a second heat exchanger, and air is an example of a gas.

The heat recovery system 10 is incorporated in the steam system 100. In addition to the heat recovery system 10, the steam system 100 includes a drain header 71 for storing drain and steam, a pump device 5 for pumping drain from the drain header 71, a water supply tank 73 for storing drain, and a boiler 74. Is equipped.

The preheater 1 preheats the air before it is heated by the main heater 2. The preheater 1 is formed of a heat exchanger. For example, the preheater 1 is a fin-and-tube type or shell-and-tube type heat exchanger. The preheater 1 has a heat transfer tube 11. A water pipe 85 through which hot water flows is connected to the upstream end of the heat transfer pipe 11. Hot water, which is a heat source, circulates inside the heat transfer tube 11. In the preheater 1, the air is heated by passing the air around the heat transfer tube 11. The upstream end of the water pipe 86 is connected to the downstream end of the heat transfer tube 11. The water flowing through the heat transfer pipe 11 flows out to the water pipe 86.

The main heater 2 further heats the air preheated by the preheater 1. The main heater 2 is formed of a heat exchanger. For example, the main heater 2 is a fin-and-tube type or shell-and-tube type heat exchanger. The main heater 2 has a heat transfer tube 21. A steam pipe 81 extending from the boiler 74 is connected to the upstream end of the heat transfer pipe 21. Steam, which is a heat source, circulates inside the heat transfer tube 21. In the main heater 2, the air is heated by passing the air around the heat transfer tube 21. The steam condenses into drain while flowing through the heat transfer tube 21. The upstream end of the drain pipe 82 is connected to the downstream end of the heat transfer pipe 21. The drain condensed in the heat transfer tube 21 flows out to the drain pipe 82.

The air heated by the main heater 2 is used to heat the object. For example, the main heater 2 is incorporated in the coating machine 20 and is used for drying an object in the coating machine 20. For example, when the coating machine 20 is used for coating the electrodes of a battery, the object is the electrodes. The heated air is used to dry the electrodes.

The recovery unit 3 is formed of a heat exchanger. The recovery unit 3 suppresses the generation of steam and recovers heat from the drain and the flash steam by exchanging heat between the drain and the steam obtained by re-evaporating the drain (hereinafter referred to as “flash steam”) and water. That is, the recovery unit 3 recovers heat not only from the drain itself from the main heater 2 but also from the flash steam in which the drain has undergone a phase change as the heat of the drain from the main heater 2.

The recovery unit 3 has a container 31 and a heat transfer tube 32 housed in the container 31 and through which water flows. The container 31 is formed in a substantially cylindrical shape. An inflow port 33 is provided in the upper part of the container 31. The downstream end of the drain pipe 82 is connected to the inflow port 33. A drain outflow pipe 34 is provided in the lower part of the container 31. The outflow pipe 34 penetrates the bottom of the container 31. The upper end of the outflow pipe 34 is opened at a position higher than the bottom of the container 31. The upstream end of the drain pipe 83 is connected to the lower end of the outflow pipe 34. The water pipe 86 is provided with a pump 86a.

The heat transfer tube 32 is formed in a spiral shape, that is, in a coil shape, about the axis of the container 31. Water flows through the heat transfer tube 32 from the bottom to the top. The downstream end of the water pipe 86 is connected to the upstream end of the heat transfer pipe 32. The upstream end of the water pipe 85 is connected to the downstream end of the heat transfer pipe 32.

Further, the recovery unit 3 has an atmospheric opening pipe 35. The air release pipe 35 extends coaxially with the axis of the container 31, penetrates the ceiling of the container 31, extends to the outside of the container 31, and is open to the atmosphere. The lower part of the atmospheric release pipe 35 extends to a position lower than the upper end of the outflow pipe 34 and opens.

Drain and flush steam flow into the container 31 through the drain pipe 82. The drain and flush steam flowing into the container 31 exchange heat with the water in the heat transfer tube 32 via the heat transfer tube 32. The flash vapor condenses into a drain. Drain is stored in the lower part of the container 31. The drain that exceeds the height of the upper end of the outflow pipe 34 flows out to the drain pipe 83 via the outflow pipe 34. The water that has flowed into the heat transfer tube 32 through the water pipe 86 is heated while flowing through the heat transfer tube 32. The water flowing out from the heat transfer pipe 32 to the water pipe 85 is hot water.

As the pressure inside the container 31 rises, the liquid level of the drain stored in the container 31 decreases. When the liquid level of the drain becomes lower than the opening at the lower part of the air opening pipe 35, the vapor or air in the container 31 is discharged to the outside of the container 31 through the air opening pipe 35. In this way, the container 31 is configured to be open to the atmosphere and is maintained at a pressure slightly higher than that of the atmosphere.

The drain header 71 stores the drain discharged from the collection unit 3. The downstream end of the drain pipe 83 is connected to the drain header 71. Further, the drain header 71 is connected to the upstream end of the drain pipe 87 from which the drain of the drain header 71 flows out.

The pump device 5 pumps the drain from the drain header 71 to the downstream side. In this example, the pump device 5 is a mechanical pump driven by steam. Since the mechanical pump is known, detailed description thereof will be omitted. The pump device 5 has a casing 51 having a drain storage chamber inside, and a float (not shown) arranged in the storage chamber.

The casing 51 is provided with an introduction port for introducing steam into the storage chamber and a discharge port for discharging steam from the storage chamber. A steam pipe 52 is connected to the introduction port. A steam pipe 53 is connected to the discharge port. In the casing 51, valves interlocking with the float are provided at each of the introduction port and the discharge port. Further, the casing 51 is connected to the downstream end of the drain pipe 87 and the upstream end of the drain pipe 88 from which the drain of the storage chamber flows out. The drain pipe 87 is provided with a check valve 87a that allows the flow of drain from the drain header 71 to the pump device 5 while blocking the flow of drain in the direction from the pump device 5 to the drain header 71. The drain pipe 88 is provided with a check valve 88a that allows the flow of fluid from the pump device 5 while blocking the flow of the opposite fluid.

When the drainage in the storage chamber of the pump device 5 is small (including the case where there is no drainage), the float is located at the lower part of the storage chamber. At this time, the pump device 5 performs a storage operation. Specifically, the inlet is closed and the outlet is open. In this state, the drain flows into the storage chamber through the drain pipe 87, and the drain is stored in the storage chamber. The float floats on the drain of the storage chamber and rises as the water level of the drain rises. The steam or air in the storage chamber is discharged from the discharge port to the steam pipe 53 as the water level of the drain rises. When the water level of the drain exceeds a predetermined water level (that is, the float rises to a predetermined height), the inlet is opened and the outlet is closed. As a result, the operation of the pump device 5 is switched from the storage operation to the pumping operation. In the pumping operation, steam is introduced from the steam pipe 52 into the storage chamber by opening the introduction port. The introduced steam pressurizes the drain in the storage chamber and flows out to the drain pipe 88.

The pump device 5 pumps the drain from the drain header 71 by repeating the storage operation and the pumping operation.

The water supply tank 73 stores a drain for supplying to the boiler 74. The downstream end of the drain pipe 88 is connected to the water supply tank 73, while the upstream end of the drain pipe 89 is connected to the water supply tank 73. The drain pipe 89 is provided with a pump 89a for pumping the drain of the water supply tank 73 to the boiler 74.

The downstream end of the drain pipe 89 is connected to the boiler 74, while the upstream end of the steam pipe 81 is connected to the boiler 74. Drain is supplied to the boiler 74 via the drain pipe 88. The boiler 74 heats the drain to generate steam. The boiler 74 discharges steam to the steam pipe 81. The steam pipe 81 is connected to a steam header or various steam-using devices. In the example of FIG. 1, the steam pipe 81 is connected to the main heater 2. The steam pipe 81 is provided with a valve 81a for adjusting the pressure of steam. The steam flowing through the steam pipe 81 is adjusted to a predetermined pressure by the valve 81a and flows into the heat transfer pipe 21 of the main heater 2.

Subsequently, the operation of the steam system 100 will be described. In FIG. 1, the solid arrow indicates the flow of water (drain), and the broken line arrow indicates the flow of steam (the same applies to FIGS. 2 to 4). In the steam system 100, steam from the boiler 74 flows into the heat transfer tube 21 of the main heater 2 via the steam pipe 81. In the main heater 2, steam heats the air through the heat transfer tube 21. The steam flowing through the heat transfer tube 21 is condensed by heating the air to become a drain. The drain discharged from the heat transfer pipe 21 is collected by the collection unit 3 via the drain pipe 82.

The drain can be re-evaporated into flash steam while flowing through the drain pipe 82 or when flowing into the container 31 of the recovery unit 3. In the recovery unit 3, the drain and flush steam come into contact with the heat transfer tube 32 to exchange heat with the water in the heat transfer tube 32. At this time, the flash vapor condenses and becomes a drain. The drain is stored in the container 31. In this way, the heat of the drain and flash steam is recovered in the water flowing through the heat transfer tube 32.

The drain stored in the container 31 is discharged to the drain pipe 83 via the outflow pipe 34 and flows into the drain header 71. The drain stored in the drain header 71 is supplied to the water supply tank 73 by the pump device 5. The drain stored in the water supply tank 73 is supplied to the boiler 74 by the pump 89a. As described above, the boiler 74 supplies steam to the main heater 2 via the steam pipe 81.

In the steam system 100 operating in this way, the recovery unit 3 of the heat recovery system 10 recovers the heat of the drain and flash steam discharged from the main heater 2 by the water flowing through the heat transfer tube 32, as described above. .. The hot water discharged from the heat transfer tube 32 is supplied to the heat transfer tube 11 of the preheater 1 via the water pipe 85.

The preheater 1 heats the air before being heated by the main heater 2. Specifically, the hot water flowing through the heat transfer tube 11 heats the air. The air heated by the preheater 1 is sent to the main heater 2 and further heated by the main heater 2. The water discharged from the heat transfer tube 11 is pumped to the heat transfer tube 32 by the pump 86a through the water pipe 86.

In this way, the heat recovery system 10 uses the heat contained in the drain and the flash steam discharged from the main heater 2 to preheat the air before being heated by the main heater 2 by the preheater 1. As a result, the amount of steam used in the main heater 2 can be reduced.

As described above, the heat recovery system 10 includes a preheater 1 (first heat exchanger) that heats air (gas) and a main heater 2 (second heat) that heats the air heated by the preheater 1 using steam as a heat source. The exchanger) and a recovery unit 3 that supplies the heat of the drain discharged from the main heater 2 to the preheater 1 as a heat source.

According to this configuration, the drain generated by heating the air in the main heater 2 is recovered, and the heat of the drain (including the heat of the flash steam generated from the drain) is used as the heat source of the preheater 1. Since the preheater 1 heats, that is, preheats the air before being heated by the main heater 2, the amount of heating in the main heater 2, that is, the amount of steam used can be reduced. In this way, the heat of the drain generated by the heating by the main heater 2 is used as a heat source for heat exchange in the preheater 1, and the heating target of the main heater 2 is preheated. As a result, the exhaust heat can be utilized with a simple configuration.

Further, the recovery unit 3 heats water by the flash steam in which the drain from the main heater 2 evaporates, and supplies the heated water to the preheater 1 as a heat source.

According to this configuration, the heat medium supplied from the recovery unit 3 to the preheater 1 is water. Therefore, the pipe for supplying the heat medium from the recovery unit 3 to the preheater 1 is the water pipe 85 through which water flows. The water pipe can be formed thinner than the steam pipe through which steam flows. This facilitates the laying of the water pipe 85 between the recovery unit 3 and the preheater 1. This is particularly effective when the pipe length between the recovery unit 3 and the preheater 1 is long.

Further, the recovery unit 2 heats water by both flash steam and drain from the main heater 2, and supplies the heated water to the preheater 1 as a heat source.

According to this configuration, the recovery unit 3 can recover not only the latent heat of the flash steam but also the sensible heat of the drain. As a result, the recovery unit 3 can recover and utilize more exhaust heat.

The preheater 1 and the main heater 2 heat air as a gas, and the main heater 2 is a heater in the coating machine 20.

According to this configuration, it is possible to suppress the generation of steam in a factory or the like where the coating machine 20 is installed, and it is possible to effectively utilize the exhaust heat and reduce the amount of steam used.

<< Embodiment 2 >>
Subsequently, the heat recovery system 210 according to the second embodiment will be described. FIG. 2 is a schematic piping diagram of the heat recovery system 210 according to the second embodiment.

The heat recovery system 210 differs from the heat recovery system 10 in that only flash steam is supplied to the recovery unit 3. Therefore, of the heat recovery system 210, the same configuration as that of the heat recovery system 10 will be described by adding the same reference numerals and omitting the description, focusing on different configurations.

The heat recovery system 210 further includes a hot well tank 271 for storing drain and flash steam discharged from the main heater 2, in addition to the preheater 1, the main heater 2, and the recovery unit 3.

The heat recovery system 210 is incorporated in the steam system 200. In addition to the heat recovery system 210, the steam system 200 includes a hot well tank 271 for storing drain and steam, a pump device 5, a water supply tank 73, and a boiler 74. The steam system 200 includes a hot well tank 271 instead of the drain header 71.

The downstream end of the heat transfer tube 21 of the main heater 2 and the hot well tank 271 are connected by a drain pipe 282a. The hot well tank 271 and the inflow port 33 of the recovery unit 3 are connected by a steam pipe 282b. Further, the hot well tank 271 and the pump device 5 are connected by a drain pipe 87.

The hot well tank 271 is open to the atmosphere or adjusted to a pressure close to atmospheric pressure. At least a part of the drain flowing from the main heater 2 to the hot well tank 271 via the drain pipe 282a is re-evaporated in the hot well tank 271 to become flush steam. The drain that flows from the main heater 2 into the hot well tank 271 and does not re-evaporate is stored in the hot well tank 271. The hot well tank 271 also stores the drain discharged from the collection unit 3.

Subsequently, the operation of the steam system 200 will be described. In the steam system 200, the steam generated by the boiler 74 is supplied to the main heater 2, and the main heater 2 heats the air. The steam flowing through the heat transfer tube 21 is condensed by heating the air to become a drain. The operation up to this point is the same as that of the steam system 100. The drain discharged from the heat transfer pipe 21 flows into the hot well tank 271 via the drain pipe 282a. The drain can re-evaporate into flush steam while flowing through the drain pipe 282a or when flowing into the hot well tank 271.

The flush steam in the hot well tank 271 flows into the container 31 of the recovery unit 3 via the steam pipe 282b. That is, drain is not supplied to the recovery unit 3, and only flash steam is supplied. The flash steam comes into contact with the heat transfer tube 32 and condenses to form a drain. The heat transfer tube 32 recovers heat from the flash steam.

The drain stored in the container 31 is discharged to the drain pipe 83 via the outflow pipe 34 and flows into the hot well tank 271. The drain stored in the hot well tank 271 is supplied to the water supply tank 73 by the pump device 5. The operation after this is the same as that of the steam system 100. The drain stored in the water supply tank 73 is supplied to the boiler 74 by the pump 89a. As described above, the boiler 74 supplies steam to the main heater 2 via the steam pipe 81.

In the heat recovery system 210, the recovery unit 3 recovers the heat of the flash steam with the water flowing through the heat transfer tube 32. The hot water discharged from the heat transfer tube 32 is supplied to the heat transfer tube 11 of the preheater 1 via the water pipe 85.

The preheater 1 heats the air before being heated by the main heater 2. The water discharged from the heat transfer tube 11 is pumped to the heat transfer tube 32 by the pump 86a through the water pipe 86.

In this way, the heat recovery system 210 uses the heat of the flash steam after the drain discharged from the main heater 2 has evaporated to preheat the air before being heated by the main heater 2 by the preheater 1. As a result, the amount of steam used in the main heater 2 can be reduced.

As described above, the heat recovery system 210 includes a preheater 1 (first heat exchanger) that heats air (gas) and a main heater 2 (second heat) that heats the air heated by the preheater 1 using steam as a heat source. The exchanger) and a recovery unit 3 that supplies the heat of the drain discharged from the main heater 2 to the preheater 1 as a heat source.

According to this configuration, the drain generated by heating the air in the main heater 2 is recovered, and the heat of the drain (including the heat of the flash steam generated from the drain) is used as the heat source of the preheater 1. Since the preheater 1 heats, that is, preheats the air before being heated by the main heater 2, the amount of heating in the main heater 2, that is, the amount of steam used can be reduced. In this way, the heat of the drain generated by the heating by the main heater 2 is used as a heat source for heat exchange in the preheater 1, and the heating target of the main heater 2 is preheated. As a result, the exhaust heat can be utilized with a simple configuration.

Further, the recovery unit 3 heats water by the flash steam in which the drain from the main heater 2 evaporates, and supplies the heated water to the preheater 1 as a heat source.

According to this configuration, the heat medium supplied from the recovery unit 3 to the preheater 1 is water. Therefore, the pipe for supplying the heat medium from the recovery unit 3 to the preheater 1 is the water pipe 85 through which water flows. The water pipe can be formed thinner than the steam pipe through which steam flows. This facilitates the laying of the water pipe 85 between the recovery unit 3 and the preheater 1. This is particularly effective when the pipe length between the recovery unit 3 and the preheater 1 is long.

<< Embodiment 3 >>
Subsequently, the heat recovery system 310 according to the third embodiment will be described. FIG. 3 is a schematic piping diagram of the heat recovery system 310 according to the third embodiment.

The heat recovery system 310 differs from the heat recovery system 10 in that the recovery unit 303 supplies flash steam to the preheater 1. Therefore, of the heat recovery system 310, the same configuration as that of the heat recovery system 10 will be described by adding the same reference numerals and omitting the description, focusing on different configurations.

The heat recovery system 310 includes a preheater 1, a main heater 2, and a recovery unit 303. The heat recovery system 310 is incorporated in the steam system 300. The steam system 300 includes a drain header 71, a pump device 5, a water supply tank 73, and a boiler 74 in addition to the heat recovery system 310.

The recovery unit 303 has a drain header 71 and an ejector pump 304. That is, the drain header 71 of the steam system 300 also functions as a part of the recovery unit 303.

The downstream end of the heat transfer tube 21 of the main heater 2 is connected to the drain header 71 via the drain pipe 82. Drain flows into the drain header 71 from the main heater 2. The drain header 71 is open to the atmosphere or adjusted to a pressure close to atmospheric pressure. At least a part of the drain flowing from the main heater 2 to the drain tank 71 through the drain pipe 82 is re-evaporated in the drain tank 71 to become flush steam. The drain that flows from the main heater 2 into the drain tank 71 and does not re-evaporate is stored in the drain tank 71. In the drain tank 71, flush steam stays in the upper space, and drain is stored in the lower space. The drain header 71 is an example of a container.

The ejector pump 304 has an ejector 341 and a pressure reducing valve 342 that regulates the pressure of the driving steam flowing into the ejector 341. The ejector pump 304 supplies the flash steam in the drain header 71 to the preheater 1. The ejector pump 304 is an example of a steam compressor.

The downstream end of the steam pipe 384 branching from the steam pipe 81 is connected to the nozzle of the ejector 341. The suction chamber of the ejector 341 is connected to the drain header 71 via a steam pipe 383. The upstream end of the steam pipe 383 communicates with the upper space of the drain header 71. The diffuser of the ejector 341 is connected to the upstream end of the heat transfer tube 11 of the preheater 1 via a steam pipe 385.

The pressure reducing valve 342 is provided in the steam pipe 384. The pressure reducing valve 342 depressurizes the steam discharged from the boiler 74 to a predetermined pressure.

The steam decompressed by the pressure reducing valve 342 is supplied to the ejector 341 as driving steam. The flash steam in the drain header 71 is sucked into the ejector 341 through the steam pipe 383 by the suction force when the driving steam flows through the ejector 341. The steam in which the driving steam and the flash steam are mixed is discharged from the ejector 341. The discharged steam is supplied to the preheater 1 via the steam pipe 385.

Steam as a heat source circulates inside the heat transfer tube 11 of the preheater 1. The air is heated by passing the air around the heat transfer tube 11. At that time, the steam condenses and becomes a drain. The downstream end of the heat transfer tube 11 is connected to the drain header 71 via the water pipe 86. The drain discharged from the heat transfer tube 11 flows into the drain header 71.

Subsequently, the operation of the steam system 300 will be described. In the steam system 300, the steam generated by the boiler 74 is supplied to the main heater 2, and the main heater 2 heats the air. The steam flowing through the heat transfer tube 21 is condensed by heating the air to become a drain. The operation up to this point is the same as that of the steam system 100. The drain discharged from the heat transfer pipe 21 is collected in the drain header 71 of the collection unit 303 via the drain pipe 82. The drain can re-evaporate into flash steam while flowing through the drain pipe 82 or when flowing into the drain header 71.

The drain stored in the drain header 71 is supplied to the water supply tank 73 by the pump device 5. The operation after this is the same as that of the steam system 100. The drain stored in the water supply tank 73 is supplied to the boiler 74 by the pump 89a. As described above, the boiler 74 supplies steam to the main heater 2 via the steam pipe 81.

In the heat recovery system 310, as described above, the recovery unit 303 supplies the evaporated flash steam of the drain discharged from the main heater 2 to the heat transfer tube 11 of the preheater 1 by the ejector pump 304.

The preheater 1 heats the air before being heated by the main heater 2. The drain discharged from the heat transfer tube 11 flows into the drain header 71 through the water pipe 86.

In this way, the heat recovery system 310 uses the heat of the flash steam after the drain discharged from the main heater 2 has evaporated to preheat the air before being heated by the main heater 2 by the preheater 1. As a result, the amount of steam used in the main heater 2 can be reduced.

As described above, the heat recovery system 310 includes a preheater 1 (first heat exchanger) that heats air (gas) and a main heater 2 (second heat) that heats the air heated by the preheater 1 using steam as a heat source. The exchanger) and a recovery unit 303 that supplies the heat of the drain discharged from the main heater 2 to the preheater 1 as a heat source.

According to this configuration, the drain generated by heating the air in the main heater 2 is recovered, and the heat of the drain (including the heat of the flash steam generated from the drain) is used as the heat source of the preheater 1. Since the preheater 1 heats, that is, preheats the air before being heated by the main heater 2, the amount of heating in the main heater 2, that is, the amount of steam used can be reduced. In this way, the heat of the drain generated by the heating by the main heater 2 is used as a heat source for heat exchange in the preheater 1, and the heating target of the main heater 2 is preheated. As a result, the exhaust heat can be utilized with a simple configuration.

The recovery unit 303 supplies the flash steam in which the drain from the main heater 2 has evaporated to the preheater 1 as a heat source.

According to this configuration, the flash steam serves as a heat source for the preheater 1. Since steam has a higher heat transfer coefficient than water, the heat transfer area of the preheater 1 can be reduced. That is, the preheater 1 can be miniaturized.

Further, the recovery unit 303 has a drain header 71 (container) into which drain flows from the main heater 2, and supplies flash steam in the drain header 71 to the preheater 1.

According to this configuration, the drain of the main heater 2 can be allowed to flow into the drain header 71 to promote the re-evaporation of the drain.

In addition, the recovery unit 303 further includes an ejector pump 304 (steam compressor) that supplies the flash steam in the drain header 1 to the preheater 1.

According to this configuration, the flash steam in the drain header 1 can be boosted by the ejector pump 304 and supplied to the preheater 1. In other words, the flash steam can be supplied to the preheater 1 even if the pressure of the flash steam in the drain header 1 is relatively low. As a result, the pressure in the drain header 1 can be made relatively low. Thereby, the re-evaporation of the drain in the drain header 1 can be further promoted.

<< Embodiment 4 >>
Subsequently, the heat recovery system 410 according to the fourth embodiment will be described. FIG. 4 is a schematic piping diagram of the heat recovery system 410 according to the fourth embodiment.

The heat recovery system 410 differs from the heat recovery system 10 in that the recovery unit 403 supplies flash steam to the preheater 1. Therefore, of the heat recovery system 410, the same configuration as that of the heat recovery system 10 will be described by adding the same reference numerals and omitting the description, focusing on different configurations.

The heat recovery system 410 includes a preheater 1, a main heater 2, and a recovery unit 403. The heat recovery system 410 is incorporated in the steam system 400. The steam system 400 includes a pump 405, a water supply tank 73, and a boiler 74 in addition to the heat recovery system 410.

The recovery unit 403 is formed of a flush tank 431. The flash tank 431 is not open to the atmosphere and is adjusted to a pressure higher than atmospheric pressure. The flash tank 431 re-evaporates the inflowing drain and separates it into drain and flash steam. The flash tank 431 stores the separated drain and flash vapor at a relatively high pressure. In the flash tank 431, flash vapor stays in the upper space, and drain is stored in the lower space. The downstream end of the heat transfer tube 21 of the main heater 2 is connected to the flash tank 431 via the drain pipe 82. The flash tank 431 is an example of a container.

The flash tank 431 is connected to the upstream end of the heat transfer tube 11 of the preheater 1 via a steam pipe 485. The upstream end of the steam pipe 485 communicates with the upper space of the flush tank 431. The flash steam in the flash tank 431 has a relatively high pressure. Therefore, the flash steam flows out from the flash tank 431 to the steam pipe 485 and is supplied to the preheater 1.

Further, the flush tank 431 is connected to the upstream end of the drain pipe 483. The drain pipe 483 communicates with the lower space of the flush tank 431. The downstream end of the drain pipe 483 is connected to the pump 405. The pump 405 is connected to the water supply tank 73 via the drain pipe 88. The pump 405 is, for example, an electric pump that pumps drainage. When the pump 405 operates, the drain stored in the flush tank 431 is sucked into the pump 405 via the drain pipe 483 and pumped from the pump 405 to the water supply tank 73.

In the preheater 1, steam flows through the inside of the heat transfer tube 11 as a heat source. The air is heated by passing the air around the heat transfer tube 11. At that time, the steam condenses and becomes a drain. A water pipe 86 is connected to the downstream end of the heat transfer pipe 11. The downstream end of the water pipe 86 is connected to the water supply tank 73. The drain discharged from the heat transfer pipe 11 flows into the water supply tank 73 via the water pipe 86.

Subsequently, the operation of the steam system 400 will be described. In the steam system 400, the steam generated by the boiler 74 is supplied to the main heater 2, and the main heater 2 heats the air. The steam flowing through the heat transfer tube 21 is condensed by heating the air to become a drain. The operation up to this point is the same as that of the steam system 100. The drain discharged from the heat transfer pipe 21 is collected by the collection unit 403 via the drain pipe 82. The drain can be re-evaporated into flash steam while flowing through the drain pipe 82 or when flowing into the recovery unit 403.

The drain stored in the collection unit 403 is supplied to the water supply tank 73 by the pump 405. The operation after this is the same as that of the steam system 100. The drain stored in the water supply tank 73 is supplied to the boiler 74 by the pump 89a. As described above, the boiler 74 supplies steam to the main heater 2 via the steam pipe 81.

In the heat recovery system 410, the flash tank 431 supplies the evaporated flash steam of the drain discharged from the main heater 2 to the heat transfer tube 11 of the preheater 1 as described above. Since the pressure in the flash tank 431 is relatively high, the flash steam is supplied to the preheater 1 by the pressure in the flash tank 431. That is, the flash steam in the flash tank 431 is supplied to the preheater 1 without being boosted.

The preheater 1 heats the air before being heated by the main heater 2. The drain discharged from the heat transfer tube 11 flows into the drain header 71 through the water pipe 86.

In this way, the heat recovery system 410 uses the heat of the flash steam after the drain discharged from the main heater 2 has evaporated to preheat the air before being heated by the main heater 2 by the preheater 1. As a result, the amount of steam used in the main heater 2 can be reduced.

As described above, the heat recovery system 410 includes a preheater 1 (first heat exchanger) that heats air (gas) and a main heater 2 (second heat) that heats the air heated by the preheater 1 using steam as a heat source. The exchanger) and a recovery unit 403 that supplies the heat of the drain discharged from the main heater 2 to the preheater 1 as a heat source.

According to this configuration, the drain generated by heating the air in the main heater 2 is recovered, and the heat of the drain (including the heat of the flash steam generated from the drain) is used as the heat source of the preheater 1. Since the preheater 1 heats, that is, preheats the air before being heated by the main heater 2, the amount of heating in the main heater 2, that is, the amount of steam used can be reduced. In this way, the heat of the drain generated by the heating by the main heater 2 is used as a heat source for heat exchange in the preheater 1, and the heating target of the main heater 2 is preheated. As a result, the exhaust heat can be utilized with a simple configuration.

Further, the recovery unit 403 supplies the flash steam obtained by evaporating the drain from the main heater 2 to the preheater 1 as a heat source.

According to this configuration, the flash steam serves as a heat source for the preheater 1. Since steam has a higher heat transfer coefficient than water, the heat transfer area of the preheater 1 can be reduced. That is, the preheater 1 can be miniaturized.

Further, the recovery unit 403 has a flash tank 431 (container) into which drain flows from the main heater 2, and supplies the flash steam in the flash tank 431 to the preheater 1.

According to this configuration, the drain of the main heater 2 can be allowed to flow into the flash tank 431 to promote the re-evaporation of the drain.

In addition, the recovery unit 403 supplies the flash steam in the flash tank 431 to the preheater 1 without boosting the pressure.

According to this configuration, the flash steam in the flash tank 431 is supplied to the preheater 1 by the pressure in the flash tank 431. That is, the configuration is simplified in that the steam compressor as described above is not required.

<< Other Embodiments >>
As described above, the above-described embodiment has been described as an example of the technology disclosed in the present application. However, the technique in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, etc. are made as appropriate. It is also possible to combine the components described in the above embodiment to form a new embodiment. In addition, among the components described in the attached drawings and the detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to exemplify the above-mentioned technology. Can also be included. Therefore, the fact that those non-essential components are described in the accompanying drawings and detailed description should not immediately determine that those non-essential components are essential.

The heat recovery systems 10, 210, 310, 410 are not limited to the steam systems 100, 200, 300, 400, and can be incorporated into any system.

The heating target of the preheater 1 and the main heater 2 is not limited to air, but may be any gas.

The configurations of the preheater 1 and the main heater 2 are not limited to the above configurations. As the preheater 1, any heat exchanger can be adopted as long as the heat of the drain in which the steam of the heat source of the main heater 2 is condensed is used as the heat source. As the main heater 2, any heat exchanger can be adopted as long as steam is used as a heat source.

The main heater 2 is not limited to the coating machine 20, and can be incorporated into various devices, equipments, systems, etc. that use heated gas. For example, the main heater 2 may be incorporated in the desiccant air conditioner.

The configuration of the container such as the drain header 71, the hot well tank 271 and the flush tank 431 is not limited thereto. Any container may be used as long as it can store drain or flush steam.

The steam compressor is not limited to the ejector pump 304, and may be, for example, an electric pump.

As described above, the techniques disclosed herein are useful for heat recovery systems.

10,210,310,410 Heat recovery system 1 Preheater (1st heat exchanger)
2 Main heater (second heat exchanger)
20 Coating machine 3,303,403 Recovery unit 71 Drain header (container)
304 Ejector pump (steam compressor)
431 Flash tank (container)

Claims (8)

The first heat exchanger that heats the gas,
A second heat exchanger that heats the gas heated by the first heat exchanger using steam as a heat source.
A heat recovery system including a recovery unit that supplies the heat of the drain discharged from the second heat exchanger to the first heat exchanger as a heat source. In the heat recovery system according to claim 1,
The recovery unit is a heat recovery system in which water is heated by flash steam in which drain from the second heat exchanger is evaporated, and the heated water is supplied to the first heat exchanger as a heat source. In the heat recovery system according to claim 2,
The recovery unit is a heat recovery system in which water is heated by both the flash steam and drain from the second heat exchanger, and the heated water is supplied to the first heat exchanger as a heat source. In the heat recovery system according to claim 1,
The recovery unit is a heat recovery system that supplies flash steam in which drain from the second heat exchanger has evaporated to the first heat exchanger as a heat source. In the heat recovery system according to claim 4,
The recovery unit has a container into which drain flows from the second heat exchanger, and is a heat recovery system that supplies flush steam in the container to the first heat exchanger. In the heat recovery system according to claim 5,
The recovery unit is a heat recovery system further comprising a vapor compressor that supplies flash steam in the container to the first heat exchanger. In the heat recovery system according to claim 5,
The recovery unit is a heat recovery system that supplies the flash steam generated in the container to the first heat exchanger without boosting the pressure. In the heat recovery system according to any one of claims 1 to 7.
The first heat exchanger and the second heat exchanger heat air as a gas, and the first heat exchanger and the second heat exchanger heat air as a gas.
The second heat exchanger is a heat recovery system that is a heater in a coating machine.

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