JP2021105490A - Vacuum type water heater - Google Patents

Abstract

To increase thermal efficiency, reduce annual energy consumption and running cost and reduce CO2 while controlling a device from being complicated and increased in size.SOLUTION: A vacuum type water heater includes: a sealed can body 2 of which interior is held to be atmospheric pressure or less; a heat medium liquid tank 4 formed in a lower part in the sealed can body 2 to store heat medium liquid 3 therein; a decompression steam chamber 5 formed in an upper part in the sealed can body 2; a hot water heat exchanger 6 disposed in the decompression steam chamber 5 to condense and liquefy steam generated inside the decompression steam chamber 5 by exchanging heat of the steam with water; and heating means 7 disposed in the heat medium liquid 3 in the heat medium liquid tank 4 to heat and evaporate the heat medium liquid 3. The heating means 7 includes: a main heater 8; and an auxiliary heating device 9 of which output power is larger than the main heater 8. The main heater 8 is disposed on a side lower than the auxiliary heating device 9.SELECTED DRAWING: Figure 1

Description

In the present invention, a closed can body whose inside is kept below atmospheric pressure, a heat medium solution tank for storing a heat medium solution formed in the lower part of the can body, and a reduced pressure vapor formed in the upper part of the can body. A hot water heat exchanger that is arranged in the chamber and the decompression steam chamber to condense and liquefy the steam generated in the decompression steam chamber by heat exchange with water, and heat that is arranged in the heat medium in the heat medium tank. The present invention relates to a vacuum type water heater which is provided with a heating means for heating and evaporating a medium liquid and is used as a hot water generator.

Conventionally, as a vacuum type water heater used as a hot water generator, for example, the one having the structure shown in FIG. 6 is known (see Patent Document 1, hereinafter referred to as the prior art 1).

That is, as shown in FIG. 6, the vacuum water heater includes a can body 51, a burner 52, a combustion chamber 53, a decompression steam chamber 54, a heat medium 55, a hot water heat exchanger 56, a water pipe 57, and an air extraction pump (not shown). ) Etc., and the inside of the can body 51 is depressurized to below atmospheric pressure by an bleeding pump to bring it into a state close to vacuum. A steam with the same temperature as the heat medium 55 at the time is generated, and the steam condenses on the surface of the hot water heat exchanger 56 to heat the water supply in the hot water heat exchanger 56 to make hot water. be.
Since the inside of the can body 51 is decompressed in this vacuum type water heater, there is an advantage that hot water at the required temperature can be quickly supplied to the load side even during high load operation in which a large amount of hot water is taken out from the hot water heat exchanger. be.

However, the vacuum type water heater in which the heat medium is heated by the combustion type burner as in the prior art 1 has a problem that the thermal efficiency is about 80% to 95%, and further, the capacity of the can body and the use. Since it is necessary to select a burner according to the fuel, there is also a problem that it is necessary to prepare various types of burners.

In order to improve the above thermal efficiency, it has been proposed to attach a heat recovery device for recovering the latent heat of water vapor contained in the combustion exhaust gas (see Patent Document 2, hereinafter referred to as the prior art 2). However, in the prior art 2, since the heat recovery device is separately provided, the entire device becomes large, and white smoke is generated because the combustion exhaust gas becomes low temperature due to heat exchange, or the water vapor in the combustion exhaust gas is condensed, which is generated. There is a problem that a liquid neutralization treatment device and corrosion countermeasures are required.

Further, in order to improve thermal efficiency, there is an invention of a vacuum type water heater using high temperature water such as a heat pump water heater and an auxiliary combustion type burner (see Patent Document 3, hereinafter referred to as prior art 3). Since the prior art 3 uses the high-temperature water as the main heat source and uses a combustion burner as an auxiliary, the can body efficiency is high, and the annual energy consumption and running cost are reduced and CO ₂ is reduced. There is an advantage that can be done. However, in the prior art 3, since the heat medium liquid tank is divided into two tanks, a heat medium liquid tank for a combustion type burner and a heat medium liquid tank for high temperature water, there is a problem that the apparatus becomes large in size. There is. Further, the hot water heat exchanger is divided into a low temperature side and a high temperature side, and the heat medium liquid condensed by the hot water heat exchanger is guided to the heat medium liquid tank for high temperature water located below the hot water heat exchanger on the low temperature side. Since the hot water heat exchanger is divided into two, there is a problem that the device becomes complicated and large.

Japanese Unexamined Patent Publication No. 11-337002 Japanese Unexamined Patent Publication No. 2012-102906 Japanese Patent No. 6359321

The present invention has been made in view of these problems, and an object of the present invention is to reduce the complexity and size of the device, to achieve high thermal efficiency, to reduce annual energy consumption and running cost, and to reduce CO ₂ The purpose is to provide a vacuum type water heater that can reduce the amount of carbon dioxide.

The present invention is configured as follows in order to solve the above problems.
That is, the vacuum water heater according to the present invention has a hermetically sealed can body whose inside is kept below atmospheric pressure, a heat medium solution tank formed in the lower part of the can body to store the heat medium solution, and the inside of the can body. A decompression steam chamber formed at the top, a hot water heat exchanger that is arranged in the decompression steam chamber and condenses and liquefies the steam generated in the decompression steam chamber by heat exchange with water, and a heat medium in a heat medium solution tank. A vacuum-type water heater provided with a heating means arranged in a liquid to heat and evaporate a heat medium liquid, wherein the heating means includes a main heater and an auxiliary heating device having a larger output than the main heater. The main heater is provided below the auxiliary heating device. The fact that the output of the auxiliary heating device is larger than that of the main heater means that the auxiliary heating device has a higher heating capacity capable of quickly heating a large amount of heat medium solution than the main heater. ..

Since the main heater and the auxiliary heating device are arranged vertically in the heat medium of the heat medium tank, there is no need to expand the installation area or divide the heat medium tank into a plurality of vacuum hot water. The size and complexity of the machine are suppressed.

The surrounding heat medium is heated by the main heater and evaporated to become heat medium vapor. The heat medium liquid vapor is cooled and condensed on the surface of the hot water heat exchanger by heat exchange with water supplied to the hot water heat exchanger, and is dropped into the hot water heat exchanger tank as droplets.

When the load on the hot water heat exchanger becomes large, such as when a large amount of hot water is taken out from the vacuum water heater, the heat medium that is cooled by the hot water heat exchanger, condenses, and drops increases, and the heat medium in the heat medium tank increases. The liquid temperature drops. Then, when the temperature of the heat medium liquid in the heat medium liquid tank becomes equal to or lower than the set temperature, the auxiliary heating device is driven. Since the output of the auxiliary heating device is larger than that of the main heater, the heat medium solution in the heat medium solution tank is rapidly heated and evaporated. As a result, the water flowing in the hot water heat exchanger is quickly heated by the heat medium liquid steam generated in a large amount, and a large amount of hot water is taken out from the vacuum type water heater.

Since the auxiliary device has a large output and is in a developed nucleate boiling state in which the surrounding heat transfer liquid boils violently on the heat transfer surface, large bubbles are formed on the heat transfer surface and are separated one after another. .. Therefore, during high-load operation in which the auxiliary heating device is driven, convection of the heat medium solution occurs in the heat medium solution tank due to the rise of bubbles separated from the heat transfer surface of the auxiliary heating device, and the heat medium solution tank. In addition to satisfactorily heating the entire heat medium inside, the heat medium around the main heater flows, further improving the heat transfer rate of the main heater.

On the other hand, during low-load operation in which the load of the hot water heat exchanger is small, such as during standby operation of the vacuum water heater, the auxiliary heating device is stopped, and bubbles do not separate or rise from the heat transfer surface. As a result, the heat medium around the main heater, which is below the auxiliary heating device, has a low temperature, and the temperature difference from the heat transfer surface of the main heater becomes large. The heat transfer solution is efficiently heated. Then, the heat medium liquid heated by the main heater rises, which heats the heat medium liquid of the entire heat medium liquid tank and increases the amount of heat storage, so that the auxiliary heating device is driven as necessary. As a result, the vacuum water heater can be quickly switched to high-load operation.

The main heater may be arranged below the auxiliary heating device, but if it is arranged at the bottom of the heat medium liquid tank, it is more suitable during low load operation when the auxiliary heating device is stopped. It is preferable because the entire heat medium solution in the heat medium solution tank can be heated by heating the main heater while heating the low temperature heat medium solution.

The main heater may be any device that is arranged in the heat medium solution tank and heats the heat medium solution in the heat medium solution tank, and is not limited to a specific heating device. For example, the main heater may be an electric heater or the like. However, if the main heater is provided with a pipe through which a fluid having a temperature higher than the temperature at which the heat medium liquid boils flows, it is preferable that heat can be efficiently exchanged with the heat medium liquid.

In particular, if the fluid is the refrigerant of the heat pump and the main heater is a refrigerant heat exchanger for cooling the refrigerant of the heat pump, that is, a condenser, for example, a hot water facility using a condenser is required separately. It is preferable that the heat medium is efficiently heated because the amount of heat generated by the heat pump is directly used in addition to being able to form a simple and compact structure.

The fluid may be a high-temperature gas such as exhaust gas discharged from a combustion burner, but high-temperature water is preferably used in addition to the refrigerant of the heat pump. Specifically, the high-temperature water includes, for example, high-temperature water obtained by a heat pump water heater, engine cooling water of a cogeneration system, high-temperature water obtained by a solar water heater, hot spring water, and other high-temperature water. To say.

The auxiliary heating device may have an output larger than that of the main heater, and may be, for example, an electric heater or engine exhaust gas. However, it is preferable that the auxiliary heating device is provided with a combustion type burner because it has a strong thermal power and can quickly heat a large amount of heat medium. The auxiliary heating device provided with a combustion type burner means a device provided with a furnace, a group of water pipes through which exhaust gas passes through, a smoke pipe line, etc., in addition to the combustion type burner, and any one or more of these is a heat medium. It is placed in the heat medium in the liquid tank.

The vacuum water heater may further include a second main heater in the heat medium solution vertically above the auxiliary heating device and below the vertical direction of the hot water heat exchanger. In this case, while the auxiliary heating device is stopped, the heat medium at the bottom of the heat medium tank around the main heater is at a low temperature, while the second main heater is in the vertical direction of the hot water heat exchanger. Since it is arranged below, the low-temperature heat medium condensed on the surface of the hot water heat exchanger has fallen into the heat medium around the second main heater. As a result, the entire heat medium solution in the heat medium solution tank is efficiently heated by the main heater and the second main heater. The magnitude of the output of the second main heater may be the same as or different from that of the main heater.

Further, when the auxiliary heating device is driven, the heat transfer solution is violently boiled on the heat transfer surface of the auxiliary heating device to generate an upward flow, so that the second main heating is arranged above the auxiliary heating device. The vessel has a significantly improved heat transfer rate on the heat transfer surface. Moreover, since the second main heater arranged above the auxiliary heating device is located near the liquid level of the heat medium liquid tank, this second main heater acts as a baffle and the movement of the liquid level is suppressed. Will be done. As a result, even when the auxiliary heating device is being driven, splashes due to boiling of the heat medium liquid are reduced from falling on the surface of the hot water heat exchanger above, and the heat of condensation of the heat medium liquid vapor is transferred to the hot water heat exchanger. Since it is efficiently transmitted to the surface of the water, there is no need to separate the hot water heat exchanger from the liquid surface or increase the size of the hot water heat exchanger, and the entire vacuum water heater is compactly formed.

The main heater stops heating while the auxiliary heating device is being driven, and heats the surrounding heat medium while the auxiliary heating device is not being driven. The main heater may heat the surrounding heat medium while the auxiliary heating device is being driven, and may stop heating while the auxiliary heating device is not being driven. In this case, during high-load operation in which the auxiliary heating device is driven, the heat medium solution is efficiently heated by the second main heater arranged above the auxiliary heating device. Further, during low-load operation in which the driving of the auxiliary heating device is stopped, the heat medium liquid heated by the main heater arranged below the auxiliary heating device rises in the heat medium liquid tank. Therefore, the entire heat medium solution in the heat medium solution tank is heated by this main heater.

The second main heater may include a pipe similar to the main heater, in which a fluid having a temperature higher than the temperature at which the heat medium liquid boils flows through the inside. In this case, the high-temperature fluid may be circulated to either one of the main heater and the second main heater via a switching valve or the like, whereby, when the load is high and when the load is low. Therefore, it is preferable to be able to switch between heating by the main heater and heating by the heater for low load.

The vacuum type water heater may include a flow device for flowing the heat medium liquid in the heat medium liquid tank between the periphery of the main heater and the vicinity of the liquid level of the heat medium liquid tank. In this case, even if the auxiliary heating device is stopped, the heat transfer solution around the heat transfer surface of the main heater moves, so that the heat transfer solution is efficiently heated on the heat transfer surface of the main heater. Will be done. Moreover, since the heat medium liquid around the main heater moves to the vicinity of the liquid surface in the heat medium liquid tank, the heat medium liquid of the entire heat medium liquid tank is heated, the amount of heat storage increases, and high load operation is performed. Can be quickly switched to.

The flow device may be, for example, a stirrer or the like arranged in the heat medium liquid tank, but between the periphery of the main heater in the heat medium liquid tank and the vicinity of the liquid level of the heat medium liquid tank. It is preferable that the heat medium liquid passage provided with the provided circulation pump has a simple structure and can compactly configure the vacuum water heater without increasing the size of the heat medium liquid tank. The circulation pump may supply the heat medium liquid around the main heater to the vicinity of the liquid surface of the heat medium liquid tank, but mainly the heat medium liquid near the liquid level of the heat medium liquid tank. When it is supplied to the periphery of the heater, an ascending flow is generated around the main heater in combination with the rise of the heat medium due to the heating of the main heater, so that it is more preferable that the surrounding heat medium can be efficiently heated.

Since the vacuum water heater of the present invention is configured and operates as described above, it has the following effects.
(1) Since the main heater of the heating means and the auxiliary heating device are arranged vertically in the heat medium liquid of the heat medium liquid tank, the installation area can be expanded or the heat medium liquid tank can be divided into a plurality of parts. There is no need to do so, and the size and complexity of the vacuum water heater can be suppressed.
(2) Since the main heater is located below the auxiliary heating device, the heat medium around the main heating device is at a low temperature while the auxiliary heating device is stopped, and the heat transfer of the main heating device is high. Since the temperature difference from the surface is large, the main heater can efficiently heat the surrounding heat medium. As a result, the thermal efficiency of the vacuum water heater is high, and the annual energy consumption and running cost _{can be reduced, and CO 2} can be reduced.
(3) Since it is equipped with an auxiliary heating device that has a larger output than the main heater, it can be easily handled by driving the auxiliary heating device during high-load operation in which a large amount of hot water is supplied from the hot water heat exchanger. be able to.
(4) Since the heat medium liquid heated by the main heater rises in the heat medium liquid tank, the heat medium liquid of the entire heat medium liquid tank is heated and heat is stored even when the auxiliary heating device is stopped. The amount will increase. Thereby, the vacuum type water heater can be quickly switched to the high load operation by driving the auxiliary heating device as needed.

It is a vertical sectional front view which shows the vacuum type water heater which concerns on embodiment of this invention, omitting a part of the vacuum type water heater. It is a vertical sectional front view which shows the vacuum type water heater which concerns on other embodiment of this invention, omitting a part of the vacuum type water heater. It is a vertical sectional front view which shows the vacuum type water heater which concerns on still another Embodiment of this invention, omitting a part of the vacuum type water heater. It is a vertical sectional side view which shows the vacuum type water heater which concerns on the modification 1 of the Embodiment of this invention, omitting a part of the vacuum type water heater. It is a vertical sectional side view which shows the vacuum type water heater which concerns on the modification 2 of the Embodiment of this invention, omitting a part of the vacuum type water heater. It is a vertical sectional view of a conventional vacuum type water heater.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a vacuum type water heater according to an embodiment of the present invention, in which the vacuum type water heater 1 is formed in a closed can body 2 whose inside is held below atmospheric pressure and a lower portion inside the can body 2. A heat medium liquid tank 4 for storing the heat medium liquid 3 (for example, water), a decompression steam chamber 5 formed in the upper part of the can body 2 and decompressed by an bleeding pump (not shown), and a decompression steam chamber. A hot water heat exchanger 6 arranged in the decompression steam chamber 5 to condense and liquefy the steam generated in the decompression steam chamber 5 by heat exchange with water, and a heat medium arranged in the heat medium liquid 3 in the heat medium liquid tank 4. A heating means 7 for heating and evaporating the liquid 3 is provided.

The hot water heat exchanger 6 is arranged in a decompression steam chamber 5 in a horizontal position, and a water inlet 6a and a hot water outlet 6b above the water inlet 6a are formed on the side wall surface of the can body 2, and the water inlet 6a is folded back. It is connected to the hot water outlet 6b via part 6c.

The heating means 7 includes a main heater 8 and an auxiliary heating device 9, and the output of the auxiliary heating device 9 is larger than the output of the main heater 8, so that a large amount of heat medium liquid 3 can be quickly applied. It has a high heating capacity that can heat up. Since the high heating capacity of the auxiliary heating device 9 differs depending on the capacity of the applied can body 2 and the like, the numerical value cannot be specifically limited, but for example, replacement of the auxiliary heating device 9 This refers to a case where the amount of heat is about 10 times or more the amount of heat exchanged by the main heater 8. The main heater 8 is arranged at the bottom of the heat medium liquid tank 4 below the auxiliary heating device 9.

A condenser, which is a refrigerant heat exchanger for cooling the refrigerant of the heat pump 11, is used in the main heater 8. That is, the introduction pipe 13 from the compressor 12 of the heat pump 11 is connected to the refrigerant inlet 8b of the main heater 8, and the outlet pipe 15 to the expansion valve 14 of the heat pump 11 is connected to the refrigerant outlet 8c of the main heater 8. Is connected.

The refrigerant of the heat pump 11 is heated by the compressor 12 to a temperature higher than the temperature at which the heat medium liquid 3 boils under the pressure inside the can body 2 (hereinafter, referred to as the saturation temperature of the heat medium liquid 3). , It is sent to the refrigerant inlet 8b of the main heater 8 via the introduction pipe 13. This high-temperature refrigerant circulates in the piping of the main heater 8 and exchanges heat with the surrounding heat medium liquid 3 to be cooled. Then, the cooled refrigerant is returned from the refrigerant outlet 8c to the heat pump 11 via the lead-out pipe 15, heated through the expansion valve 14, the evaporator 16 and the compressor 12 in this order, and again to the refrigerant inlet 8b of the main heater 8. Sent.

On the other hand, since the heat transfer surface 8a of the main heater 8 is heated to a temperature higher than the saturation temperature of the heat medium liquid 3 by the heated refrigerant, the surrounding heat medium liquid 3 is heated and the heat medium liquid steam. It becomes. At this time, although the temperature of the heat transfer surface 8a of the main heater 8 heated by the refrigerant is higher than the saturation temperature, the degree of superheat, which is the difference from the saturation temperature of the heat medium liquid 3, is low.

However, since the temperature of the heat medium liquid 3 is low at the bottom of the heat medium liquid tank 4 below the auxiliary heating device 9 where the main heater 8 is arranged, the heat transfer surface of the main heater 8 is provided. The temperature difference between 8a and the surrounding heat medium is large, and the main heater 8 efficiently heats the surrounding heat medium 3. Then, since the heat medium liquid 3 efficiently heated by the main heater 8 rises in the heat medium liquid tank 4 and convects, the main heater 8 is stopped even when the auxiliary heating device 9 is stopped. As a result, the entire heat medium solution 3 in the heat medium solution tank 4 is heated, and the amount of heat stored increases.

In this embodiment, since the condenser of the heat pump is used for the main heater 8, the amount of heat generated by the heat pump is directly generated by the refrigerant of the heat pump 11 in the heat medium liquid 3 around the main heater 8. It is used and the heat medium solution 3 is efficiently heated. On the other hand, in the heat pump 11, when the main heater 8 can only partially heat the heat medium liquid 3 in the heat medium liquid tank 4, the refrigerant is not sufficiently cooled and the heat medium liquid at the bottom of the heat medium liquid tank 4 is removed. Even though the temperature is low, it may be judged that the temperature rise is completed and the temperature may stop. However, in this embodiment, since the main heater 8 heats the entire heat medium liquid 3 in the heat medium liquid tank 4, the risk of the heat pump stopping is reduced. Further, since the condenser of the heat pump 11 used for the main heater 8 is arranged in the sealed can body 2, the risk of corrosion is reduced, and the refrigerant of the heat pump 11 leaks from the condenser by any chance. Even so, since the water in the hot water heat exchanger 6 is cut off, there is no possibility that the refrigerant of the heat pump 11 will be mixed in the hot water taken out from the hot water heat exchanger 6.

The heat medium liquid steam generated by heating the main heater 8 is cooled by heat exchange with water supplied to the hot water heat exchanger 6 on the surface of the hot water heat exchanger 6 in the decompression steam chamber 5. Condenses into droplets and drops into the heat medium liquid tank 4. On the other hand, the water supplied to the hot water heat exchanger 6 is heated by heat exchange with the heat medium liquid steam, whereby hot water having a desired temperature is taken out from the hot water heat exchanger 6.

The load on the hot water heat exchanger 6 becomes larger than the heating capacity of the main heater 8 (hereinafter, both during high load operation), such as when a large amount of hot water is taken out from the hot water heat exchanger 6 of the vacuum water heater 1. The heat medium liquid 3 that is cooled by the hot water heat exchanger 6 and condensed and dropped increases, and the temperature of the heat medium liquid 3 in the heat medium liquid tank 4 decreases. Therefore, when the temperature of the heat medium liquid 3 detected by the liquid temperature detector 19 attached to the heat medium liquid tank 4 becomes equal to or lower than the set temperature, the auxiliary heating device 9 is driven by the control device 20. Whether or not it is during high-load operation is determined by determining the magnitude of the load based on, for example, the amount of hot water taken out from the hot water heat exchanger 6, instead of determining by the temperature of the heat medium liquid 3, and the auxiliary heating device. The drive of 9 may be controlled.

The auxiliary heating device 9 includes a combustion burner 21 as a heat source, a furnace 22 as a combustion chamber, a group of water pipes 23, and an exhaust stack 24. The furnace 22 and the water pipe 23 group are submerged in the heat medium liquid 3 in the heat medium liquid tank 4, and the main heater 8 is arranged below the furnace 22 in the vertical direction. The peripheral surface of the furnace 22 and the inner surface of the water pipe 23 are in contact with the heat transfer liquid 3, and serve as a heat transfer surface 9a to the heat medium liquid 3.

When the combustion burner 21 is driven by the control device 20, the heat transfer surface 9a of the auxiliary heating device 9 is heated by the strong thermal power of the combustion burner 21. The heat medium liquid 3 in the heat medium liquid tank 4 is heated by the main heater 8 and has a large amount of heat storage. Therefore, when the heat transfer surface 9a of the auxiliary heating device 9 having a large output is heated, the furnace The heat medium liquid 3 around 22 and the heat medium liquid 3 flowing in the water pipe 23 are quickly heated, the hot water heat exchanger 6 is switched to high load operation, and the main heating is insufficient for the increased hot water load. The heating capacity of the vessel 8 is well supplemented.

On the other hand, when the load on the hot water heat exchanger 6 decreases and becomes smaller than the heating capacity of the main heater 8, the amount of condensed heat medium 3 dripping from the surface of the hot water heat exchanger 6 decreases, and the heat medium tank 4 The temperature of the heat medium solution 3 inside rises. Then, when the liquid temperature detector 19 detects that the temperature of the heat medium liquid 3 exceeds the set temperature, the control device 20 stops driving the auxiliary heating device 9. As a result, the auxiliary heating device 9 using the combustion burner 21 has a large amount of heat medium, such as when the hot water load is high or when the heat medium 3 is to be heated quickly when the vacuum water heater 1 is started. Since it is driven only when 3 is heated rapidly, it is possible to improve the efficiency of the can body, reduce the annual energy consumption and running cost, and reduce CO ₂ .

Since the main heater 8 is arranged below the auxiliary heating device 9, it is not necessary to expand the installation area of the vacuum water heater 1 or divide the heat medium liquid tank 4 into a plurality of vacuum type water heaters. The water heater 1 is compactly formed while being suppressed from becoming large and complicated.

FIG. 2 shows a vacuum water heater according to another embodiment of the present invention, in which the heating means 7 of the vacuum water heater 1 is in the heat medium solution 3 vertically above the auxiliary heating device 9. A second main heater 10 is provided below the hot water heat exchanger 6 in the vertical direction.

The second main heater 10 uses the same condenser of the heat pump 11 as the main heater 8, and has a smaller output than the auxiliary heating device 9 like the main heater 8. The output of the second main heater 10 may be about the same as or different from the output of the main heater 8. The refrigerant inlet 10b of the second main heater 10 is connected to the introduction pipe 13 from the compressor 12 of the heat pump 11 via the introduction branch pipe 17, and the refrigerant outlet 10c of the second main heater 10 is connected. , The heat pump 11 is connected to the lead-out pipe 15 to the expansion valve 14 via the lead-out branch pipe 18. Other configurations are the same as those of the vacuum water heater shown in FIG. 1, and the same effects can be obtained. Therefore, the same reference numbers are assigned to the same parts and members as those of the vacuum water heater shown in FIG. The detailed description thereof will be omitted.

While the auxiliary heating device 9 is stopped, the heat medium liquid 3 at the bottom of the heat medium liquid tank 4 around the main heater 8 is at a low temperature, so that the main heater 8 is the same as in the above embodiment. The surrounding heat medium liquid 3 is efficiently heated. On the other hand, since the second main heater 10 is arranged below the hot water heat exchanger 6 in the vertical direction, the low-temperature heat medium liquid 3 condensed on the surface of the hot water heat exchanger 6 is around the second main heater 10. The second main heater 10 efficiently heats the surrounding heat medium liquid 3. As a result, the heat medium is formed by the main heater 8 arranged below the auxiliary heating device 9 and the second main heating device 10 arranged in the heat medium solution 3 above the auxiliary heating device 9. The entire heat medium liquid 3 in the liquid tank 4 is efficiently heated.

During high-load operation in which a large amount of hot water is taken out from the hot water heat exchanger 6, the temperature of the heat medium liquid 3 in the heat medium liquid tank 4 drops as in the above embodiment, so that the auxiliary heating device 9 is used. Driven. The auxiliary heating device 9 has a large output, and the surrounding heat medium liquid 3 is in a developed nucleate boiling state in which it boils violently. Then, the large bubbles formed on the heat transfer surface are separated one after another and rise, so that an upward flow of the heat medium solution 3 is generated above the auxiliary heating device 9. As a result, in the second main heater 10 arranged above the auxiliary heating device 9, the heat transfer coefficient is remarkably improved because the heat medium liquid 3 around the heat transfer surface 10a flows by this rising flow. ..

By heating the auxiliary heating device 9, a large number of bubbles of the heat medium liquid 3 vapor are generated from the heat transfer surface 9a of the auxiliary heating device 9. However, since the second main heater 10 arranged above the auxiliary heating device 9 is located near the liquid level of the heat medium liquid tank 4, the second main heater 10 looks like a baffle. It acts to suppress the movement of the liquid surface. As a result, even when the auxiliary heating device 9 is being driven, the splashes of the boiling heat medium liquid 3 are reduced from falling on the surface of the hot water heat exchanger 6 above, so that the heat of condensation of the heat medium liquid vapor is reduced. Is efficiently transmitted to the surface of the hot water heat exchanger 6. As a result, it is not necessary to separate the hot water heat exchanger 6 from the liquid surface or increase the size of the hot water heat exchanger 6, and the entire vacuum water heater 1 is compactly formed.

Since the heat medium liquid 3 heated by the main heater 8 rises in the heat medium liquid tank 4, the entire heat medium liquid 3 can be heated by the main heater 8. Therefore, while the auxiliary heating device 9 is stopped, the heating of the second main heater 10 may be stopped. Further, during high load operation, if the entire heat medium liquid 3 in the heat medium liquid tank 4 is sufficiently heated by the heating of the auxiliary heating device 9, it is possible to stop the heating of the main heater 8. be.

Therefore, as shown in FIG. 2, switching valves 17a and 18a are provided at the connection portion between the introduction pipe 13 and the introduction branch pipe 17 and the connection portion between the lead-out pipe 15 and the lead-out branch pipe 18, respectively, for low load operation. The switching valves 17a and 18a may be controlled so that the refrigerant of the heat pump is sometimes guided to the main heater 8 and the refrigerant of the heat pump is guided to the second main heater 10 during high load operation. As a result, even when the load is low, the entire heat medium solution 3 in the heat medium solution tank 4 can be heated, but either the heating by the main heater 8 or the heating by the second main heater 10 can be performed. Since it is used, the efficiency of the can body is further improved, and the annual energy consumption and running cost _{can be further reduced and CO 2} can be further reduced.

FIG. 3 shows a vacuum type water heater according to another embodiment of the present invention. In this vacuum type water heater 1, the heat medium solution 3 in the heat medium solution tank 4 is placed around the main heater 8 and the heat medium solution. A flow device 25 for flowing between the tank 4 and the vicinity of the liquid level is provided. That is, a heat transfer passage 27 provided with a circulation pump 26 is provided between the bottom of the heat medium liquid tank 4 around the main heater 8 and the vicinity of the liquid level of the heat medium liquid tank 4. The heat medium liquid passage 27 provided with the circulation pump 26 constitutes the flow device 25. Other configurations are the same as those of the vacuum water heater shown in FIG. 1, and the same effects can be obtained. Therefore, the same reference numbers are assigned to the same parts and members as those of the vacuum water heater shown in FIG. The detailed description thereof will be omitted.

In the circulation pump 26, when the temperature of the heat medium liquid 3 detected by the liquid temperature detector 19 attached to the heat medium liquid tank 4 becomes equal to or lower than the set temperature while the auxiliary heating device 9 is stopped. Driven by the control device 20, the heat medium liquid 3 near the liquid level of the heat medium liquid tank 4 is guided to the bottom of the heat medium liquid tank 4 via the heat medium liquid passage 27, and is supplied to the periphery of the main heater 8. NS. Since the heat medium liquid 3 around the main heater 8 flows by the supply of the heat medium liquid 3, the heat medium liquid 3 is efficiently heated on the heat transfer surface 8a of the main heater 8. Further, since the heat medium liquid 3 near the liquid surface of the heat medium liquid tank 4 moves to the periphery of the main heater 8, an ascending flow passing around the main heater 8 is generated in the heat medium liquid tank 4. The heat medium solution 3 of the entire heat medium solution tank 4 is heated. As a result, the amount of heat stored increases, so that the hot water heat exchanger 6 can be quickly switched to high-load operation by driving the auxiliary heating device 9 as needed.

In this embodiment, since the circulation pump 26 guides the heat medium liquid 3 on the liquid surface of the heat medium liquid tank 4 to the bottom of the heat medium liquid tank 4, the heat medium liquid is contained in the heat medium liquid tank 4. It is preferable that the ascending flow of 3 is likely to occur and the heat transfer liquid 3 of the entire heat medium liquid tank 4 is satisfactorily heated. However, in the present invention, the circulation pump 26 may guide the heat medium liquid 3 at the bottom of the heat medium liquid tank 4 to the vicinity of the liquid surface of the heat medium liquid tank 4, and in this case as well, the main heater 8 may be used. The same effect as that of this embodiment can be obtained in that the heat medium liquid 3 flows around and the entire heat medium liquid 3 in the heat medium liquid tank 4 can be heated. Further, in this embodiment, the flow device 25 is configured by the heat transfer passage 27 provided with the circulation pump 26, but the flow device 25 used in the present invention mainly heats the heat medium solution 3 in the heat medium solution tank 4. Any device may be used as long as it is a device that flows between the periphery of the heat transfer surface 8a of the vessel and the vicinity of the liquid surface of the heat medium liquid tank 4, and may be, for example, a stirrer or the like arranged in the heat medium liquid tank 4.

The present invention is not limited to each of the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, in each of the above embodiments, a heat pump condenser was used as the main heater 8. However, the main heater used in the present invention may be any device that is arranged in the heat medium solution tank to heat the heat medium solution, and is not limited to a specific heating device. For example, it is possible to use a pipe through which a fluid such as high-temperature water or high-temperature gas flows, an electric heater, or the like. The high-temperature water that can be used for the main heater is, for example, high-temperature water obtained by a heat pump water heater, engine cooling water of a cogeneration system, high-temperature water obtained by a solar water heater, hot spring water, or other high-temperature water. And so on.

Further, in each of the above embodiments, as the auxiliary heating device 9, a combustion type burner 21 and a device including a furnace 22 submerged in the heat medium liquid 3 in the heat medium liquid tank 4 and a group of water pipes 23 are used. .. However, the auxiliary heating device used in the present invention may be any device that can quickly heat a large amount of heat medium, and may be, for example, an electric heater or engine exhaust gas.

Further, in each of the above embodiments, the main heater 8 is arranged vertically below the furnace 22 of the auxiliary heating device 9. However, the main heater of the present invention may be arranged below the auxiliary heating device. However, when the main heater is arranged below a part or all of the auxiliary heating device in the vertical direction, the installation area of the entire vacuum water heater can be further reduced, which is preferable. For example, as in the first modification shown in FIG. 4, the main heater 8 may be arranged vertically below the water pipe 23 group of the auxiliary heating device 9, or as in the second modification shown in FIG. The main heater 8 may be arranged vertically below the furnace 22 and the smoke tube 28 of the auxiliary heating device 9.

1 ... Vacuum type water heater 2 ... Can body 3 ... Heat medium liquid 4 ... Heat medium liquid tank 5 ... Decompression steam chamber 6 ... Hot water heat exchanger 7 ... Heating means 8 ... Main heater 9 ... Auxiliary heating device 10 ... No. 2 Main heater 11 ... Heat pump 21 ... Combustion burner 25 ... Flow device 26 ... Circulation pump 27 ... Heat medium liquid passage

Claims (9)

A closed can body whose inside is kept below atmospheric pressure, a heat medium liquid tank formed in the lower part of the can body to store the heat medium liquid, a decompression steam chamber formed in the upper part of the can body, and decompression. A hot water heat exchanger that is placed in the steam chamber and condenses and liquefies the steam generated in the decompression steam chamber by heat exchange with water, and a hot water heat exchanger that is placed in the heat medium liquid in the heat medium liquid tank to heat the heat medium liquid. A vacuum water heater equipped with a heating means for evaporating.
The heating means includes a main heater and an auxiliary heating device having a larger output than the main heater.
The vacuum type water heater, wherein the main heater is arranged below the auxiliary heating device. The vacuum type water heater according to claim 1, wherein the main heater is arranged at the bottom of a heat medium liquid tank. The vacuum hot water according to claim 1 or 2, wherein the main heater includes a pipe through which a fluid having a temperature higher than the temperature at which the heat medium is boiled under the pressure inside the can flows. Machine. The vacuum water heater according to claim 3, wherein the high-temperature fluid is a refrigerant of a heat pump, and the main heater is a condenser for cooling the refrigerant of the heat pump. The vacuum water heater according to any one of claims 1 to 4, wherein the auxiliary heating device includes a combustion burner. The heating means further includes a second main heater in a heat medium solution vertically above the auxiliary heating device and below the hot water heat exchanger in the vertical direction, according to claims 1 to 5. The vacuum water heater described in any of. The main heater stops heating while the auxiliary heating device is being driven, and heats the surrounding heat medium while the auxiliary heating device is not being driven.
The second main heater heats the surrounding heat medium while the auxiliary heating device is being driven, and stops heating while the auxiliary heating device is stopped. Item 6. The vacuum water heater according to item 6. The vacuum type according to any one of claims 1 to 7, further comprising a flow device for flowing the heat medium liquid in the heat medium liquid tank between the periphery of the main heater and the vicinity of the liquid level of the heat medium liquid tank. Water heater. The vacuum according to claim 8, wherein the flow device is a heat medium liquid passage provided with a circulation pump provided between the periphery of the main heater in the heat medium liquid tank and the vicinity of the liquid level of the heat medium liquid tank. Type water heater.

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