JP7390187B2 - Vacuum water heater - Google Patents

Description

The present invention includes a hermetically sealed can whose inside is maintained at below atmospheric pressure, a heat transfer liquid tank formed in the lower part of the can to store a heat transfer liquid, and a reduced pressure steam formed in the upper part of the can. a hot water heat exchanger placed in the reduced pressure steam chamber to condense and liquefy the steam generated in the reduced pressure steam chamber through heat exchange with water; The present invention relates to a vacuum water heater that is equipped with a heating means for heating and evaporating a liquid medium and is used as a hot water generator.

Conventionally, as a vacuum water heater used as a hot water generator, for example, one having a structure shown in FIG. 5 is known (see Patent Document 1, hereinafter referred to as Prior Art 1).

That is, as shown in FIG. 5, the vacuum water heater includes a can body 51, a burner 52, a combustion chamber 53, a reduced pressure steam chamber 54, a heat medium water 55, a hot water heat exchanger 56, a water pipe 57, and an air extraction pump (not shown). ) etc., the inside of the can body 51 is depressurized to below atmospheric pressure by an air extraction pump to create a near-vacuum state, and in this state, the heat transfer water 55 is heated to boiling by the burner 52, and the water is released into the reduced pressure steam chamber 54. This system generates steam that has the same temperature as the heat transfer water 55 at that time, and the steam condenses on the surface of the hot water heat exchanger 56 to heat the water supplied in the hot water heat exchanger 56 and create hot water. be.
This vacuum type water heater has the advantage of being able to quickly supply hot water at the required temperature to the load side even during high-load operation when a large amount of hot water is extracted from the hot water heat exchanger because the pressure inside the can body 51 is reduced. be.

However, in a vacuum water heater that heats heat medium water using a combustion burner as in Conventional Technology 1, there is a problem that the thermal efficiency is only about 80% to 95%. Since it is necessary to select a burner according to the fuel, there is also the problem that it is necessary to prepare many types of burners.

In order to improve the above-mentioned thermal efficiency, it has been proposed to attach a heat recovery device that recovers the latent heat of water vapor contained in the combustion exhaust gas (see Patent Document 2, hereinafter referred to as Prior Art 2). However, in Conventional Technology 2, the heat recovery device is provided separately, which increases the size of the entire device, and the flue gas becomes colder due to heat exchange, resulting in white smoke, and condensation occurs as water vapor in the flue gas condenses. There are problems that require liquid neutralization equipment and corrosion countermeasures.

Furthermore, in order to increase thermal efficiency, there is an invention of a vacuum water heater using high temperature water and an auxiliary combustion burner, such as a heat pump water heater (see Patent Document 3, hereinafter referred to as Prior Art 3). This conventional technology 3 uses the high-temperature water as the main heat source and uses a combustion type burner as an auxiliary, so the can body efficiency is high and the annual energy consumption and running costs are reduced, as well as CO ₂ emissions. It has the advantage of being able to However, in Conventional Technology 3, the heat medium liquid tank is divided into two tanks, one for the combustion burner and the other for high-temperature water, resulting in the problem of an increase in the size of the device. There is. Furthermore, the hot water heat exchanger is divided into a low temperature side and a high temperature side, and the heat medium liquid condensed in the hot water heat exchanger is guided to a high temperature water heat medium liquid tank located below the low temperature side hot water heat exchanger. However, since the hot water heat exchanger is divided into two parts, there is a problem that the equipment becomes complicated and large.

Japanese Patent Application Publication No. 11-337002 JP2012-102906A Patent No. 6359321

The present invention has been made in view of these problems, and its purpose is to suppress the complexity and size of the device while achieving high thermal efficiency, reducing annual energy consumption and running costs, and reducing CO ₂ An object of the present invention is to provide a vacuum type water heater that can reduce the amount of water used.

In order to solve the above problems, the present invention is constructed as follows.
That is, the vacuum water heater according to the present invention includes a sealed can whose inside is maintained at atmospheric pressure or lower, a heat medium liquid tank formed at the lower part of the can to store a heat medium liquid, and a A reduced pressure steam chamber formed in the upper part, a hot water heat exchanger placed in the reduced pressure steam chamber to condense and liquefy the steam generated in the reduced pressure steam chamber through heat exchange with water, and a heat medium in a heat medium liquid tank. A vacuum water heater equipped with a heating means disposed in a liquid to heat and evaporate a heat transfer liquid, the heating means comprising a main heater and an auxiliary heating device having a larger output than the main heater. The auxiliary heating device is arranged vertically below the main heater.

The surrounding heat medium liquid is heated by the main heater and turns into heat medium liquid vapor. This heat medium liquid vapor is cooled and condensed on the surface of the hot water heat exchanger by heat exchange with the water supplied to the hot water heat exchanger, and drops into the heat medium liquid tank in the form of droplets. At this time, although the temperature of the heat transfer surface of the main heater is higher than the temperature at which the heat transfer liquid boils under the pressure inside the can (hereinafter referred to as the saturation temperature of the heat transfer liquid), the difference from the saturation temperature is Since the degree of superheat is low, the heat transfer surface of this main heater is in a partial nucleate boiling state with only a few boiling bubbles visible.

When the load on the hot water heat exchanger increases, such as when a large amount of hot water is taken out of a vacuum water heater, the amount of heat medium liquid that is cooled by the hot water heat exchanger, condenses, and drips increases, causing the heat medium in the heat medium liquid tank to increase. Liquid temperature decreases. 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 greater than that of the main heater, the heat medium liquid in the heat medium liquid tank is rapidly heated and evaporated. As a result, the water flowing through the hot water heat exchanger is efficiently heated by the large amount of heat medium liquid vapor generated, and a large amount of hot water is taken out from the vacuum water heater. Note that the output of the auxiliary heating device is greater than that of the main heater means that the auxiliary heating device has a higher heating capacity than the main heater to be able to quickly heat a large amount of heat medium liquid. .

The auxiliary heating device has a large output, and its heat transfer surface is in a state of advanced nucleate boiling where the surrounding heating medium boils violently, so large bubbles are formed on the heat transfer surface and are separated one after another. do. Due to the rise of the separated bubbles and the heated heat medium liquid, an upward flow of the heat medium liquid is generated around the main heater disposed above the auxiliary heating device. As a result, the heat medium liquid flows around the heat transfer surface of the main heater, and the heat transfer coefficient of the main heater is significantly improved.

The heating of the auxiliary heating device generates many bubbles of heat medium liquid vapor from its heat transfer surface, but the main heater placed above the auxiliary heating device is located near the liquid level of the heat medium liquid tank. Therefore, this main heater plays the role of a baffle, and the floating of the liquid level is suppressed. As a result, splashes of boiling liquid are reduced from falling on the surface of the hot water heat exchanger above, and the risk of inhibiting the condensation heat transfer of the heat medium liquid vapor is reduced. There is no need to separate the vacuum water heater or increase the size of the hot water heat exchanger, and the entire vacuum water heater can be made compact.

In addition, since the main heater and the auxiliary heating device of the heating means are arranged one above the other in the heat medium liquid of the heat medium liquid tank, it is necessary to expand the installation area or divide the heat medium liquid tank into multiple parts. This prevents the vacuum water heater from becoming larger and more complex.

The main heater may be any device that is disposed in the heat medium liquid tank and heats the heat medium liquid in the heat medium liquid tank, and is not limited to a specific heating device. For example, the main heater may be an electric heater. However, it is preferable that the main heater is provided with piping through which a fluid having a temperature higher than the boiling temperature of the heat medium liquid flows, since heat can be efficiently exchanged with the heat medium liquid.

In particular, if the fluid is a refrigerant for a 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 separate hot water facility using a condenser is required. First, it is possible to have a simple and compact configuration, and the amount of heat generated by the heat pump is directly utilized, so the heat medium liquid is efficiently heated, which is preferable.

Further, the fluid may be 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 a heat pump. The high-temperature water specifically includes, for example, high-temperature water obtained from a heat pump water heater, engine cooling water for a cogeneration system, high-temperature water obtained from a solar water heater, hot spring water, and other high-temperature water. means.

The auxiliary heating device only needs to have a higher output than the main heater, and may be, for example, an electric heater or engine exhaust gas. However, it is preferable that the auxiliary heating device includes a combustion type burner because the heating power is strong and a large amount of heat medium liquid can be quickly heated. Note that an auxiliary heating device equipped with a combustion burner refers to a device equipped with a combustion burner, a furnace, a group of water pipes around which exhaust gas passes, a smoke pipe, etc., and one or more of these are equipped with a heat medium It is placed vertically below the main heater in the heat medium liquid in the liquid tank.

The auxiliary heating device is driven during high-load operation when the load on the hot water heat exchanger is large, but is stopped during low load when the load on the hot water heat exchanger is small, such as during standby operation of a vacuum water heater. When the auxiliary heating device is stopped, the surrounding heat medium liquid and the heat medium liquid vapor in the vacuum steam chamber above are heated by the main heater located above, but the heat generated by the heating of the main heater is The fluid flow is limited to the area around the main heater. As a result, the heat medium liquid at the bottom of the heat medium liquid tank is not easily heated.

Therefore, the heating means may include a low-load heater in the heat medium liquid below the auxiliary heating device. When the auxiliary heating device is stopped, the heat medium liquid at the bottom of the heat medium liquid tank below the auxiliary heating device is heated by the low-load heater, and as a result, the heat medium liquid in the heat medium liquid tank is heated by the low-load heater. The entire heat transfer liquid is heated. At this time, since the auxiliary heating device is stopped, the heat medium liquid at the bottom of the heat medium liquid tank is at a low temperature, and the temperature difference between it and the heat transfer surface of the heater for low load is large. The heat medium liquid at the bottom of the heat medium liquid tank is efficiently heated. Therefore, the magnitude of the output of this heater for low load times may be the same as or different from that of the main heater. By heating the heat medium liquid in the entire heat medium liquid tank, the amount of heat storage increases, and the hot water heat exchanger can be quickly switched to high-load operation, which is preferable.

The main heater heats the surrounding heat medium liquid while the auxiliary heating device is being driven, and stops heating while the auxiliary heating device is not being driven, and is configured to The temporary heater may stop heating while the auxiliary heating device is being driven, and may heat the surrounding heat medium liquid while the auxiliary heating device is not being driven. In this case, during high-load operation when the auxiliary heating device is being driven, the heat medium liquid is efficiently heated by the main heater disposed above the auxiliary heating device. In addition, during low-load operation when the auxiliary heating device is stopped, the heat medium liquid heated by the low-load heater placed below the auxiliary heating device is transferred to the heat medium liquid tank. Since the heat medium liquid rises inside the heat medium liquid tank, the entire heat medium liquid in the heat medium liquid tank is heated by this heater for low load times.

The low-load heater may include piping, similar to the main heater, through which a fluid having a temperature higher than the boiling temperature of the heat transfer fluid flows. In this case, the high-temperature fluid may flow through a switching valve or the like to either the main heater or the low-load heater, so that the high-load and low-load It is preferable to be able to switch between heating by the main heater and heating by the low-load heater at different times.

The vacuum water heater may include a flow device that causes the heat medium liquid in the heat medium liquid tank to flow between the periphery of the heat transfer surface of the main heater and the bottom of the heat medium liquid tank. In this case, even when the auxiliary heating device is stopped, the heat medium liquid around the main heater moves, so that the heat medium liquid is efficiently heated on the main heating heat transfer surface. Moreover, since the heat medium liquid at the bottom of the heat medium liquid tank moves to the surroundings of the main heater, the heat medium liquid in the entire heat medium liquid tank is heated, increasing the amount of heat storage and increasing the temperature of the hot water heat exchanger. This is preferable because it can quickly switch to load operation.

The flow device may be, for example, a stirrer placed in the heat medium liquid tank, or a circulation pump provided between the bottom of the heat medium liquid tank and the vicinity of the liquid surface of the heat medium liquid tank. With a heat medium liquid path having a simple structure, the heat medium liquid in the heat medium liquid tank can be made to flow between the periphery of the heat transfer surface of the main heater and the bottom of the heat medium liquid tank. Moreover, the vacuum water heater can be configured compactly without increasing the size of the heat medium liquid tank, which is preferable. Note that even if the circulation pump moves the heat medium liquid near the liquid surface to the bottom, it can heat the entire heat medium liquid in the heat medium liquid tank, and also heat the heat medium liquid around the main heater. It is preferable because it can be moved, but it is more preferable to supply the heat medium liquid at the bottom near the liquid surface because low temperature heat medium liquid can be supplied around the main heater and heating can be performed efficiently.

Since the vacuum water heater of the present invention is configured and operates as described above, it has the following effects.
(1) The main heating device and the auxiliary heating device are arranged one above the other in the heat medium liquid of the heat medium liquid tank, so the installation area can be expanded or the heat medium liquid tank can be divided into multiple parts. There is no need for this, and it is possible to prevent the vacuum water heater from becoming larger and more complex.
(2) Since the main heater is disposed above the auxiliary heating device, the main heater is located near the liquid level of the heat medium liquid tank and can function as a baffle. As a result, even if a large number of boiling bubbles are generated from the heat transfer surface of the auxiliary heating device, their movement on the heat medium liquid surface can be suppressed, and droplets of boiling liquid can be prevented from falling on the surface of the hot water heat exchanger above. It can be reduced. As a result, the heat of condensation of the heat medium liquid vapor can be efficiently transferred to the water in the hot water heat exchanger, and there is no need to separate the hot water heat exchanger from the liquid surface or make the hot water heat exchanger larger, so it is possible to The entire water heater can be made compact.
(3) Since the main heater is located above the auxiliary heating device, when the auxiliary heating device is in operation, the heating medium liquid rises due to boiling in the auxiliary heating device, causing the surrounding area of the main heater to rise. The heat transfer fluid flows and the heat transfer coefficient of the main heater is significantly improved. As a result, although the vacuum water heater is compact, it has high thermal efficiency, and it is possible to reduce annual energy consumption, running costs, and CO ₂ emissions.
(4) Since the auxiliary heating device has a larger output than the main heater, it is possible to easily cope with the high load of the hot water heat exchanger by driving the auxiliary heating device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view showing a vacuum water heater according to an embodiment of the present invention, with some parts of the vacuum water heater omitted. It is a vertical cross-sectional front view showing a vacuum water heater according to another embodiment of the present invention, with a part of the vacuum water heater omitted. It is a longitudinal sectional front view showing a vacuum water heater according to still another embodiment of the present invention, with some parts of the vacuum water heater omitted. FIG. 7 is a longitudinal sectional side view showing a modification of the embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of a conventional vacuum water heater.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.
FIG. 1 shows a vacuum type water heater according to an embodiment of the present invention. A heat medium liquid tank 4 which stores a heat medium liquid 3 (for example, water), a reduced pressure steam chamber 5 formed in the upper part of the can 2 and whose pressure is reduced by an air extraction pump (not shown), and a reduced pressure steam chamber 5. A hot water heat exchanger 6 is disposed in the heat medium liquid 3 in the heat medium liquid tank 4 and condenses and liquefies the steam generated in the reduced pressure steam chamber 5 through heat exchange with water. A heating means 7 for heating and evaporating the liquid 3 is provided.

The hot water heat exchanger 6 is arranged in a horizontal position in the reduced pressure steam chamber 5, and a water inlet 6a and a hot water outlet 6b above it are formed on the side wall surface of the can body 2, and the water inlet 6a is turned around. It is connected to the hot water outlet 6b via the section 6(c).

The heating means 7 includes a main heater 8 and an auxiliary heating device 9 disposed in the heat medium liquid 3 of the heat medium liquid tank 4, and the output of the auxiliary heating device 9 is connected to the main heater. 8, and has a high heating capacity capable of quickly heating a large amount of heat medium liquid 3. Note that the high heating capacity of the auxiliary heating device 9 varies depending on the capacity of the can body 2 to which it is applied, so it cannot be specifically limited to a numerical value; This refers to cases where the amount of heat is about 10 times or more the amount of heat exchanged by the main heater 8. The auxiliary heating device 9 is arranged vertically below the main heater 8.

The main heater 8 includes a condenser that is a refrigerant heat exchanger for cooling the refrigerant of the heat pump 11. That is, an inlet pipe 13 from the compressor 12 of the heat pump 11 is connected to the refrigerant inlet 8b of the main heater 8, and an 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 saturation temperature of the heat medium liquid 3, and then sent to the refrigerant inlet 8b of the main heater 8 via the introduction pipe 13. This high-temperature refrigerant flows through the piping of the main heater 8, exchanges heat with the surrounding heat medium liquid 3, and is cooled. The cooled refrigerant is then returned to the heat pump 11 from the refrigerant outlet 8c via the lead-out pipe 15, heated through the expansion valve 14, the evaporator 16, and the compressor 12 in this order, and then returned to the refrigerant inlet 8b of the main heater 8. Sent.

On the other hand, the heat transfer surface 8a of the main heater 8 is heated by the heated refrigerant to a temperature higher than the saturation temperature of the heat medium liquid 3, so the surrounding heat medium liquid 3 is heated and vaporized into heat medium liquid vapor. becomes. At this time, although the temperature of the heat transfer surface 8a heated by the refrigerant is higher than the saturation temperature, the degree of superheating, which is the difference from the saturation temperature of the heat transfer liquid 3, is low, and the heat transfer surface 8a is heated by the heat transfer surface 8a. It is in a partial nucleate boiling state with only a few bubbles visible. However, the surrounding heat medium liquid 3 is efficiently heated and evaporated by the refrigerant of the heat pump 11 because the amount of heat generated by the heat pump is directly utilized.

The heat medium liquid vapor generated by the heating of 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 reduced pressure steam chamber 5. The heat medium is condensed into droplets and dripped 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 vapor, and thereby hot water at a desired temperature is taken out from the hot water heat exchanger 6.

When a large amount of hot water is taken out from the hot water heat exchanger 6 of the vacuum water heater 1, the load on the hot water heat exchanger 6 becomes larger than the heating capacity of the main heater 8 (hereinafter referred to as "high load operation"). ), the heat medium liquid 3 that is cooled and condensed in the hot water heat exchanger 6 and drips 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 . Note that whether or not it is a high-load operation is determined by determining the magnitude of the load based on the amount of hot water taken out from the hot water heat exchanger 6, for example, instead of determining based on the temperature of the heat medium liquid 3, and determining whether the auxiliary heating device 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 pipe 24. The furnace 22 and a group of water tubes 23 are submerged in the heat medium liquid 3 in the heat medium liquid tank 4, and the furnace 22 is arranged vertically below the main heater 8. The peripheral surface of the furnace 22 and the inner surface of the water tube 23 are in contact with the heat transfer liquid 3, and serve as a heat transfer surface 9a to the heat transfer 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. As a result, the heat medium liquid 3 around the furnace 22 and the heat medium liquid 3 flowing in the water pipes 23 are quickly heated, and the heating capacity of the main heater 8 that is insufficient for the increased hot water load is well compensated for. .

When the combustion type burner 21 of the auxiliary heating device 9 is driven, the heat transfer surface 9a is heated to a temperature considerably higher than the saturation temperature, so that the surrounding heat transfer liquid 3 undergoes a developed nucleate boiling that boils violently. state. Then, the large bubbles formed on the heat transfer surface 9a separate one after another and rise, so that an upward flow of the heat medium liquid 3 is generated above the auxiliary heating device 9. Since the main heater 8 is arranged above the auxiliary heating device 9, when the upward flow occurs, the heat medium liquid 3 around the heat transfer surface 8a flows in the main heater 8, and the main heater 8 flows. The heat transfer coefficient of the heater 8 is significantly improved. The water flowing through the hot water heat exchanger 6 is heated by the heat medium liquid vapor that is efficiently heated and evaporated by the main heater 8 and the auxiliary heating device 9, and a large amount of hot water is taken out from the hot water outlet 6b. It will be done.

Note that, due to the heating of the auxiliary heating device 9, many bubbles of vapor of the heat transfer liquid 3 are generated from the heat transfer surface 9a thereof. However, since the main heater 8 placed above the auxiliary heating device 9 is located near the liquid level of the heat medium liquid tank 4, the main heater 8 acts like a baffle and the liquid The movement of the surface is suppressed. As a result, even while the auxiliary heating device 9 is being driven, splashes of the boiling heat medium liquid 3 are prevented from falling on the surface of the hot water heat exchanger 6 above, and the heat of condensation of the heat medium liquid vapor is reduced. It is efficiently transmitted to the surface of the hot water heat exchanger 6.

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 liquid 3 dripping from the surface of the hot water heat exchanger 6 decreases, and the amount of the heat medium liquid in the heat medium liquid tank 4 decreases. The temperature of the heat transfer liquid 3 increases. 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 type burner 21 can handle a large amount of heat medium liquid when the hot water load is high or when it is desired to quickly raise the temperature of the heat medium liquid 3 when starting the vacuum water heater 1. Since it is activated only when rapidly heating the fuel, it is possible to improve the efficiency of the can body, reduce annual energy consumption and running costs, and reduce CO ₂ emissions.

The heating means 7 can efficiently heat the heat medium liquid 3 in the heat medium liquid tank 4, and the vapor of the heat medium liquid 3 is efficiently heat exchanged on the surface of the hot water heat exchanger 6. Moreover, since the main heater 8 and the auxiliary heating device 9 are arranged one above the other in the heat medium liquid tank 4, it is possible to expand the installation area of the vacuum water heater 1 or to divide the heat medium liquid tank 4 into multiple parts. There's no need to. As a result, the vacuum water heater 1 is prevented from increasing in size and complexity, and is formed compactly.

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 placed in a heat medium liquid below the auxiliary heating device 9 during low load. It is equipped with a heater 10 for use.

The low-load heater 10 uses a condenser of a heat pump 11 similar to the main heater 8. The refrigerant inlet 10b of the heater 10 for low load is connected to the introduction pipe 13 from the compressor 12 of the heat pump 11 via an introduction branch pipe 17, and the refrigerant outlet of the heater 10 for low load is connected to the introduction pipe 13 from the compressor 12 of the heat pump 11. 10c is connected to a lead-out pipe 15 to the expansion valve 14 of the heat pump 11 via a lead-out branch pipe 18. The rest of the structure is similar to that of the vacuum water heater shown in Figure 1, and the same functions and effects can be achieved, so the same parts and members as the vacuum water heater shown in Figure 1 are designated with the same reference numbers. The detailed explanation will be omitted.

The auxiliary heating device 9 is driven during high-load operation when the load on the hot water heat exchanger 6 is large, but it is driven during low-load operation when the load on the hot water heat exchanger 6 is small, such as during standby operation of the vacuum water heater 1. will be stopped. When the auxiliary heating device 9 is stopped, the main heater 8 arranged above the auxiliary heating device 9 heats the heat medium liquid 3 in the upper part of the heat medium liquid tank 4 and the reduced pressure steam chamber 5 in the upper part. The heat medium liquid vapor in the heat medium liquid tank 4 is heated, and the heat medium liquid 3 at the bottom of the heat medium liquid tank 4 is heated by the low-load heater 10 disposed below the auxiliary heating device 9.

At this time, since the auxiliary heating device 9 is stopped, the heat medium liquid 3 at the bottom of the heat medium liquid tank 4 is at a low temperature. As a result, even if the low-load heater 10 is a condenser of a heat pump and has a smaller output than the auxiliary heating device 9, the heat transfer surface 10a of the low-load heater 10 and the surrounding The temperature difference between the heating medium liquid 3 and the heating medium liquid 3 is large, and the surrounding heating medium liquid 3 is efficiently heated.

As described above, even when the auxiliary heating device 9 is stopped, the heat medium liquid 3 in the entire heat medium liquid tank 4 is heated by the main heater 8 and the low-load heater 10. Therefore, the amount of heat storage increases, and the hot water heat exchanger 6 can be quickly switched to high-load operation.

Furthermore, when a heat pump condenser is used as the main heater 8, the heat medium liquid 3 in the heat medium liquid tank 4 is only partially heated, so the refrigerant in the condenser is not sufficiently cooled, and the heat medium liquid 3 in the heat medium liquid tank 4 is heated only partially. Even though the heat transfer liquid at the bottom of the heat pump is at a low temperature, there is a risk that the heat pump may be determined to have completed the temperature rise and be stopped. However, in this embodiment, by using the low-load heater 10, the heat medium liquid 3 in the entire heat medium liquid tank 4 is heated by the refrigerant of the heat pump, so the possibility of the heat pump stopping is reduced. .

The heat medium liquid 3 heated by the low load heater 10 rises in the heat medium liquid tank 4, so the entire heat medium liquid 3 can be heated by the low load heater 10. . Therefore, during low-load operation when the auxiliary heating device 9 is stopped, the surrounding heat medium liquid 3 may be heated by the low-load heater 10, and the heating of the main heater 8 may be stopped. In addition, 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, the surrounding heat medium liquid 3 is heated by the main heater 8. At the same time, it is also possible to stop the heating of the heater 10 for low load.

Therefore, as shown in FIG. 2, switching valves 17a and 18a are provided at the connection between the inlet pipe 13 and the inlet branch pipe 17, and at the connection between the outlet pipe 15 and the outlet branch pipe 18, respectively. The switching valves 17a and 18a may be controlled so that the refrigerant of the heat pump is sometimes guided to the heater 10 for low-load operation, and the refrigerant of the heat pump is guided to the main heater 8 during high-load operation. As a result, the entire heat medium liquid 3 in the heat medium liquid tank 4 can be heated even during low load, but only one of the heating by the main heater 8 and the heating by the low load heater 10 can be performed. is used, the can body efficiency is further improved, annual energy consumption and running costs are reduced, and CO ₂ emissions can be further reduced.

FIG. 3 shows a vacuum type water heater according to another embodiment of the present invention. A fluidizing device 25 is provided to cause the fluid to flow between the heating medium and the bottom of the heat medium liquid tank 4. That is, a heat medium liquid path 27 equipped with a circulation pump 26 is provided between the bottom of the heat medium liquid tank 4 and the vicinity of the liquid surface of the heat medium liquid tank 4. The liquid path 27 constitutes the flow device 25. The rest of the structure is similar to that of the vacuum water heater shown in Figure 1, and the same functions and effects can be achieved, so the same parts and members as the vacuum water heater shown in Figure 1 are designated with the same reference numbers. The detailed explanation will be omitted.

The circulation pump 26 operates 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 at the bottom of the heat medium liquid tank 4 is guided to the liquid surface of the heat medium liquid tank 4 through the heat medium liquid path 27, and is supplied around the main heater 8. . This supply of the heat medium liquid 3 causes the heat medium liquid 3 around the main heater 8 to flow, so that the heat medium liquid 3 is efficiently heated on the heat transfer surface 8a. In addition, since the heat medium liquid 3 at the bottom of the heat medium liquid tank 4 moves to the vicinity of the main heater 8, the heat medium liquid 3 in the entire heat medium liquid tank 4 is heated and the amount of heat storage increases. The heat exchanger 6 can be quickly switched to high-load operation.

In this embodiment, since the circulation pump 26 guides the heat medium liquid 3 at the bottom of the heat medium liquid tank 4 to the liquid surface of the heat medium liquid tank 4, the lower temperature heat medium liquid 3 is used for main heating. This is preferable because it is supplied around the vessel 8 and heated efficiently. However, in the present invention, the circulation pump 26 may guide the heat medium liquid 3 near the liquid surface of the heat medium liquid tank 4 to the bottom of the heat medium liquid tank 4; The same effects as this embodiment can be achieved in that the heat medium liquid 3 flows around the heat medium liquid 3 and the entire heat medium liquid 3 in the heat medium liquid tank 4 can be heated. Further, in this embodiment, the fluidizing device 25 is configured with the heat medium liquid path 27 equipped with the circulation pump 26, but the fluidizing device 25 used in the present invention mainly heats the heat medium liquid 3 in the heat medium liquid tank 4. Any device may be used as long as it allows the heat medium to flow between the periphery of the heat transfer surface 8a of the vessel 8 and the bottom of the heat medium liquid tank 4. For example, it may be a stirrer or the like disposed within the heat medium liquid tank.

The present invention is not limited to the above-described 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 is used as the main heater 8. Therefore, there is an advantage that the amount of heat generated by the heat pump is directly utilized. Moreover, since this condenser is placed in the heat medium liquid inside a sealed can kept below atmospheric pressure, the risk of corrosion is reduced, and in the unlikely event that the heat pump's refrigerant leaks from the condenser. Even if it leaks, it is isolated from the water in the hot water heat exchanger, so there is also the advantage that there is no risk of the heat pump's refrigerant getting mixed into the hot water taken out from the vacuum water heater.

However, the main heater used in the present invention is not limited to a specific heating device, as long as it is a device that is placed in the heat medium liquid tank and heats the heat medium liquid. For example, it is also possible to use piping through which a fluid such as high-temperature water or high-temperature gas flows, an electric heater, or the like. High-temperature water that can be used in the main heater includes, for example, high-temperature water obtained from a heat pump water heater, engine cooling water for a cogeneration system, high-temperature water obtained from a solar water heater, hot spring water, and other high-temperature water. etc. can be mentioned.

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

Further, in each of the above embodiments, the furnace 22 of the auxiliary heating device 9 was arranged vertically below the main heater 8, but in the present invention, the main heater 8 The group of water pipes 23 of the auxiliary heating device 9 may be arranged vertically below. In addition, if the smoke pipe connected to the furnace 22 of the auxiliary heating device 9 is placed submerged in the heat medium liquid 3, even if the smoke pipe is placed vertically below the main heater 8. good.

1...Vacuum type water heater 2...Can body 3...Heat medium liquid 4...Heat medium liquid tank 5...Reduced pressure steam chamber 6...Hot water heat exchanger 7...Heating means 8...Main heater 9...Auxiliary heating device 10...Low Load heater 11...Heat pump 21...Combustion type burner 25...Flow device 26...Circulation pump 27...Heat medium liquid path

Claims (7)

A sealed can whose inside is kept below atmospheric pressure, a heat transfer liquid tank formed in the lower part of the can to store a heat transfer liquid, a reduced pressure steam chamber formed in the upper part of the can, and a reduced pressure A hot water heat exchanger is placed in the steam chamber to condense and liquefy the steam generated in the reduced pressure steam chamber through heat exchange with water, and a hot water heat exchanger 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, an auxiliary heating device having a larger output than the main heater , and a low-load heater disposed in the heat medium liquid below the auxiliary heating device. Equipped with
The vacuum water heater , wherein the auxiliary heating device is disposed vertically below the main heater. The vacuum water heater according to claim 1, wherein the main heater includes piping through which a fluid having a temperature higher than the boiling temperature of the heat transfer liquid flows. The vacuum water heater according to claim 2, wherein the high temperature fluid is a heat pump refrigerant, and the main heater is a condenser for cooling the heat pump refrigerant. The vacuum water heater according to any one of claims 1 to 3, wherein the auxiliary heating device includes a combustion burner. The main heater heats the surrounding heat medium liquid while the auxiliary heating device is being driven, and stops heating while the auxiliary heating device is not being driven;
The low-load heater stops heating while the auxiliary heating device is being driven, and heats the surrounding heat medium liquid while the auxiliary heating device is not being driven. The vacuum water heater according to claim 1 . 6. The heating medium liquid tank according to claim 1, further comprising a flow device that causes the heat medium liquid in the heat medium liquid tank to flow between the periphery of the heat transfer surface of the main heater and the bottom of the heat medium liquid tank. Vacuum water heater. 7. The vacuum water heater according to claim 6 , wherein the flow device is a heat medium liquid path including a circulation pump provided between the bottom of the heat medium liquid tank and near the liquid surface of the heat medium liquid tank.