JP5580225B2 - Vacuum water heater - Google Patents

Description

  The present invention relates to a vacuum water heater, and is particularly useful as a vacuum water heater that is an industrial hot water generator.

  Conventionally, various types of industrial hot water generators are used, but vacuum water heaters are frequently used as hot water generators for obtaining hot water of 100 ° C. or less. The vacuum water heater burns fuel such as city gas, kerosene, and pellets, and exchanges heat of the combustion heat and exhaust gas with heat transfer water existing around the combustion chamber. The heat transfer water boils under reduced pressure at about 80 ° C. to 90 ° C. in a reduced pressure evaporation chamber that has been depressurized under atmospheric pressure, and warms the hot water through a heat exchanger in the same chamber. The heat transfer water exchanges heat with the combustion exhaust gas through a heat transfer tube provided in the combustion chamber, but usually recovers heat up to an exhaust gas temperature of about 200 ° C. The thermal efficiency is approximately 90%.

  Specific examples of such a vacuum water heater include a vacuum hot water boiler having a configuration as shown in FIG. 3 (see, for example, Patent Document 1). A combustion chamber 104 is provided so as to be immersed in the heat medium water 103 inside the heat medium water storage tank (can body) 101 in which the heat medium water 103 is sealed so that the steam chamber 102 is formed in the upper part, and a burner 105 is provided. The top position of the heat transfer water storage tank 101 is connected to the top of the heat transfer water storage tank 101 via a vacuum line 107 provided with an on-off valve 108, and the upper position in the heat transfer water storage tank 101 serving as the steam chamber 102 The heat transfer pipe 110 as a heat exchanger that allows the water 109 to be heated to circulate from the outside is provided, and the inside of the heat transfer water storage tank 101 is evacuated by the operation of the vacuum pump 106. In this state, by burning the burner 105, the heat transfer water 103 is heated through the wall surface of the combustion chamber 104, so that the heat transfer water 103 in the vacuum has a temperature of 100 ° C. or lower. For example, by boiling and evaporating rapidly at about 80 ° C., the generated reduced-pressure steam fills the steam chamber 102 and condenses on the surface of the heat transfer tube 110, thereby exchanging heat with the water 109 flowing through the heat transfer tube 110. Thus, the hot water 109a heated up to the temperature of the reduced-pressure steam from the outlet of the heat transfer tube 110 can be recovered. In addition, 111 is an exhaust port of the combustion chamber 104, 112 is a fire weir installed at the center of the combustion chamber 104 so as to face the burner 105, and 113 is a combustion chamber 104 in a portion that becomes a flue behind the fire weir 112. Is a water pipe for heat transfer provided so as to penetrate through in the vertical direction. By using condensation heat transfer, the heat transfer area can be reduced, and the temperature of the condensation region of the heat transfer water 103 under reduced pressure is set as the control temperature, so that the water 109 that is the heating target fluid is intermittently heat-exchanged. Even in such a case, the temperature of the heat transfer water 103 does not change greatly, and therefore, the hot water 109a heated to a constant temperature can always be produced (Patent Document 1, paragraphs 0003 to 0003). 0004).

JP 2003-279160 A

However, the vacuum water heater as described above sometimes has the following problems and problems.
(I) In the conventional system, the temperature of the heat transfer water is normally maintained in a state of being heated to 80 ° C. to 90 ° C., and the cold water is heat-exchanged with the hot water by the heat exchanger in the reduced pressure steam chamber. In the conventional structure, since the exhaust gas temperature cannot be made lower than the heat transfer water temperature, there is a problem that it is difficult to increase the efficiency of the boiler in terms of structure.
(Ii) If an economizer is installed separately from the water heater to recover heat from the exhaust gas, the economizer falls under the pressure vessel for heat exchange with the exhaust gas. Since there is a danger that the boiling point will be exceeded, hot water will blow out to the outside if it should rupture.

  The object of the present invention is to efficiently recover the combustion heat of the flue gas discharged from the combustion burner provided in the water heater to supply the desired warm water, and to prevent the temperature and pressure inside the water heater from rising. Another object of the present invention is to provide a vacuum water heater that is free from danger when ruptured.

  As a result of intensive studies, the present inventors have found that the above-described object can be achieved by a vacuum water heater shown below, and have completed the present invention.

The present invention is a vacuum water heater,
A combustion chamber provided with a combustion burner, an upper water pipe group, and an upper exhaust part; a convection chamber provided below the combustion chamber; and provided with an exhaust gas flow passage and a lower water pipe group or a smoke pipe group and a lower exhaust part; A connection path connecting the upper exhaust part and the exhaust gas flow passage, disposed in an upper part of the combustion chamber, a decompression steam chamber connected to the upper water pipe group, and disposed in a lower part of the convection chamber, A lower heat medium chamber connected to the lower water pipe group or the smoke pipe group, and a main body unit comprising:
An upper heat exchange space that communicates with the decompression steam chamber through an upper communication channel and that is filled with a gas phase heat medium, and a lower portion that communicates with the lower heat medium chamber and a lower communication channel and that is filled with a liquid phase heat medium. A heat exchange unit in which a heat exchange space is formed, a second heat exchange unit is disposed in the upper heat exchange space, and a first heat exchange unit is disposed in the lower heat exchange space;
It is characterized by having.

  As described above, in the vacuum water heater, efficient recovery of the combustion heat of the combustion exhaust gas becomes a major issue. In the present invention, when recovering combustion heat, the combustion exhaust gas and the heat medium used for recovery are exchanged in two stages, and both fluids are subjected to countercurrent heat exchange in each stage, thereby achieving extremely high heat. It was found that exchange efficiency can be obtained. That is, in the main unit, a combustion chamber is disposed above and a convection chamber is disposed below, and the combustion exhaust gas is circulated from above to form the upper high temperature condition and the lower low temperature condition. The heat from the combustion exhaust gas can be recovered very efficiently and the heat medium vaporized from above can be taken out by circulating the heat upward from the top and exchanging heat countercurrently at each stage. Moreover, in a vacuum water heater, it becomes a subject to produce warm water efficiently using the heat of the used heat medium. The present invention performs two-stage heat exchange between the heat medium and the water to be heated when using the heat of the heat medium, and both fluids exchange heat countercurrently in each stage. It has been found that not only the latent heat of the heat medium but also sensible heat can be absorbed, and a very high heat exchange efficiency can be obtained. That is, in the heat exchange unit, the high-temperature heat medium heated in the main body unit is circulated from the upper side to the lower side, and the second heat exchange unit is arranged on the upper side, and the first heat exchange unit is arranged on the lower side. In the second heat exchange section, the feed water absorbs the latent heat of the heat medium and heats it up while the heat medium is heated. Condensed by heat and heated in the first heat exchange section by absorbing sensible heat from the condensed heat medium and circulating heat medium in which the feed water has fallen, while the heat medium is cooled by heat supply and is very efficient The hot heat of the heat medium was recovered, and it was possible to take out the high-temperature warm water from the upper second heat exchange section.

  Furthermore, when the water heater is in operation, a heat medium circulation system is formed in the main unit and the heat exchange unit. At this time, a flow resistance of the heat medium is generated along with the circulation and transfer of the heat medium, so that a water level difference is generated between the main unit and the heat exchange unit. Such a water level difference functions as a driving force by circulating and transferring the heat medium, and can automatically form a circulation system (natural circulation system). The present invention separates the circulation system of the heat medium into a main unit and a heat exchange unit. In the heat exchange unit, the heat exchange is efficiently performed by two heat exchangers, and a water level difference between the main unit and the heat exchange unit is achieved. And having a function of transporting and propelling the heat medium that forms the circulation system. With the configuration as described above, it is possible to recover the combustion heat of the combustion exhaust gas discharged from the combustion burner provided in the water heater and supply the desired warm water with an unprecedented high efficiency, and the exhaust gas. High efficiency can be ensured without installing a facility to exchange heat directly between exhaust gas and hot water, such as an economizer, preventing a rise in the temperature and pressure inside the water heater, and further avoiding the danger of explosion It became possible to provide a water heater.

The present invention is the above-described vacuum water heater, wherein the main unit includes an intermediate heat medium chamber that connects the upper water pipe group and the lower water pipe group or the smoke pipe group between the combustion chamber and the convection chamber. It is characterized by that.
As described above, in the main unit of the water heater according to the present invention, heat exchange in two stages (in the combustion chamber and the convection chamber) is performed by the water tube group or the smoke tube group. At this time, in the combustion chamber and the convection chamber, there may be a difference in the heating state by the combustion exhaust gas between the tubes in the water tube group or the smoke tube group depending on the position of the water tube or the smoke tube, and from the water tube in the combustion chamber to the convection chamber water tube or the smoke tube If the heat medium that circulates inside the pipe in a connected state is continuously circulated, it may affect the efficiency balance of heat exchange or the formation of stepwise heat exchange. The present invention clearly divides the heat recovery function at each stage, and once gathers the heat medium from below, makes the heat medium uniform in temperature, and the water pipe group in the upper combustion chamber It became possible to ensure efficient heat recovery.

The present invention is the above-described vacuum water heater, wherein the heat exchange unit is filled with a space filled with a part of the liquid heat medium communicating with the lower heat exchange space in the upper heat exchange space and the lower heat exchange unit. The upper space portion and the lower space portion formed only from the lower heat exchange space are divided into two upper and lower spaces, and the upper space portion and the lower space portion are connected by a circulation pump.
As described above, the transfer amount of the heat medium flowing through the circulation system is equivalent to the combustion load factor and the water level of the heat medium in the upper water tube group or the smoke tube group of the main unit (the average water level is equivalent in the case of a gas-liquid mixed state). The difference in water level between the main unit and the heat exchange unit is defined by the flow resistance of the entire system, and the water level of each unit is determined by the transfer amount and flow resistance of the heat medium flowing through this circulation system. Stable at the balance position. On the other hand, if the combustion load factor increases, the transfer amount of the heat medium flowing through the circulation system increases, the flow resistance increases, and the water level difference also increases. However, when the combustion load factor increases rapidly, such a water level difference may not always follow. In the present invention, the circulation pump is disposed in the liquid layer of the heat medium of the heat exchange unit constituting the heat medium circulation system, so that not only the water level difference but also the forced heat medium transfer capability in the circulation system. Even if there is a change in operating conditions due to an increase in the combustion load factor, etc., the heat exchange function is improved by smooth circulation of the heat medium, further increasing the combustion heat of the combustion exhaust gas. It became possible to collect with high efficiency. Here, the “combustion load factor” refers to the amount of heat generated in the space volume per unit of the combustion chamber.

Further, the present invention is the above vacuum water heater,
The flue gas generated in the combustion chamber is reduced in temperature by exchanging heat in the upper water pipe group, introduced into the convection chamber through the upper exhaust part and the connection path, and heated in the lower water pipe group or the smoke pipe group. The temperature is reduced by exchanging, passing through the exhaust gas flow passage, and discharged from the lower exhaust part,
A heat medium filling the inside of the upper water pipe group absorbs combustion heat by heat exchange with the combustion exhaust gas, and a part of the heat medium is heated and vaporized, and is transferred to the upper heat exchange space through the vacuum steam chamber. The temperature is reduced and condensed by exchanging heat in the second heat exchanging unit, dripped into the lower heat exchange space as a condensate, and circulates in the lower water tube group or the smoke tube group through the lower heat medium chamber. Heat exchange and heating, transferred upward, and circulating through the upper water tube group through the intermediate heat medium chamber, forming a circulation flow,
Supply water is distribute | circulated from the said 1st heat exchange part to the said 2nd heat exchange part, and is supplied as heating water, It is characterized by the above-mentioned.
In the vacuum water heater, two-stage heat exchange is performed, in which the heat generated in the combustor is absorbed by the heat medium directly or through the combustion exhaust gas, and is further absorbed by the supply water through the heat medium. At this time, the present invention verifies how the exhaust gas, the heat medium, and the heat-absorbing-side supply water as the medium for transferring the heat can be utilized to the maximum extent. The present inventors have found that heated water can be taken out from the supplied water in an extremely efficient and stable manner by forming the flow of the supplied water as described above. In addition, such a configuration does not require an equipment such as an economizer to exchange heat directly between the exhaust gas and hot water, thus preventing an increase in temperature and pressure inside the water heater, ensuring high safety, and excellent It became possible to obtain high thermal efficiency.

Overall configuration diagram showing a basic configuration example (first configuration example) of a vacuum water heater according to the present invention Overall configuration diagram showing a second configuration example of a vacuum water heater according to the present invention Overall configuration diagram illustrating the outline of a vacuum hot water boiler according to the prior art

  The vacuum water heater according to the present invention (hereinafter referred to as “the main water heater”) includes the following main body unit and heat exchange unit. The main unit has a combustion chamber provided with a combustion burner, an upper water pipe group, and an upper exhaust part, and is disposed below the combustion chamber, and an exhaust gas passage and a lower water pipe group or a smoke pipe group (hereinafter referred to as “lower water pipe group etc.”). ) And a convection chamber provided with a lower exhaust part, a connection path connecting the upper exhaust part and the exhaust gas flow passage, a decompression steam chamber disposed in the upper part of the combustion chamber and connected to the upper water tube group, and a convection chamber And a lower heat medium chamber connected to the lower water tube group and the like, and the heat exchange unit communicates with the reduced pressure steam chamber through the upper communication channel, and is filled with a gas phase heat medium. A lower heat exchange space that is in communication with the exchange space, the lower heat medium chamber, and the lower communication flow path and is filled with a liquid phase heat medium is formed, and a second heat exchange portion is provided above the upper heat exchange space. The 1st heat exchange part is arrange | positioned under the 2 heat exchange part. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Basic configuration example of this water heater>
As one embodiment of this water heater, the basic configuration is schematically shown in FIG. 1A (first configuration example). FIG. 1B shows an AA cross section of the combustion chamber 1. In the present water heater, the main unit 10 and the heat exchange unit 20 are communicated with each other through the upper communication channel Lu and the lower communication channel Lb, and the heat medium is transferred from the main unit 10 to the heat exchange unit 20 through the upper communication channel Lu. It is transferred and transferred from the heat exchange unit 20 to the main unit 10 via the lower communication flow path Lb. By such a cyclic movement of the heat medium, efficient heat transfer can be performed. The main unit 10 includes a combustion chamber that is a source of heat and a primary heat transfer field, a convection chamber 2 that is a secondary heat transfer field, a connection path 3 that is a heat transfer field, The heat exchange unit 20 has a decompression steam chamber 4 and a lower heat medium chamber 5, and is a third heat transfer field and a second heat exchange section 6, which is a discharge end of warm heat, and a fourth heat transfer unit. It has the 1st heat exchange part 7 which is a place, and forms the upper heat exchange space 8 and the lower heat exchange space 9 which are places of heat transfer. Here, water such as city water is usually used as the heat medium. The transfer of the heat medium that forms the circulation system in the hot water heater uses a natural circulation system due to a water level difference caused by flow resistance in the heat medium flow path generated by the combustion heat. Therefore, the transfer amount of the heat medium flowing through the circulation system is defined by the combustion load factor and the water level of the main unit 10, and the water level difference between the main unit 10 and the heat exchange unit 20 is defined by the distribution resistance of the entire system, The water level of the units 10 and 20 is stabilized at a position where the transfer amount of the heat medium flowing through the circulation system and the flow resistance balance.

  Here, in this water heater, the heat generated in the combustor 1 is absorbed into the heat medium directly or through the combustion exhaust gas, and further, heat is absorbed into the supply water through the heat medium, and two-stage heat exchange is performed. It is. Further, also in the first stage of transferring the heat to the heat medium, the main body unit 10 performs two-stage heat exchange in a countercurrent manner. Specifically, heat exchange under high temperature conditions is performed in the combustion chamber 1 disposed above, and heat exchange under low temperature conditions is performed in the convection chamber 2 disposed below. Further, also in the stage of transferring the warm heat from the heat medium to the supply water, the heat exchange unit 20 performs two-stage heat exchange counter-currently. Specifically, heat exchange (high temperature absorption of latent heat) in the high temperature condition of the gas phase heat medium and the feed water in the second heat exchange section 6 disposed above, and first heat exchange disposed below. Heat exchange (sensible heat absorption) of the liquid phase heat medium and the feed water in the section 7 is performed at a low temperature. In other words, the heat of the water heater is converted into a heat source by a heating function that involves a phase change of the heat medium that forms a heat energy circulation system, and a two-stage heat exchange function between the combustion exhaust gas and the feed water. As much as possible, the thermal efficiency of the water heater can be improved.

[Main unit]
As illustrated in FIGS. 1A and 1B, the main unit 10 includes a combustion burner 1a, an upper water pipe group 1b (consisting of a front water pipe group 1e and a rear water pipe group 1f), and an upper exhaust part 1c. A combustion chamber 1 is provided. In the combustion chamber 1, a flame 1d is generated by a combustion reaction between separately supplied fuel and combustion air (not shown), and thermal energy is radiated. These thermal energies are absorbed by a heat medium that circulates in the upper water pipe group 1b in which a plurality of water pipes are arranged. That is, the combustion heat of the combustion exhaust gas is absorbed mainly through the rear water tube group 1f, and the radiant heat energy of the flame 1d is absorbed through the front water tube group 1e. As described above, by appropriately disposing the upper water pipe group 1b in the combustion chamber 1, it is possible to efficiently absorb heat. Here, the water pipes constituting the upper water pipe group 1b are set so that the steam flow velocity at the outlet of the water pipe is about 2 to 6 m / s at the rated load in order to obtain a necessary transfer amount of the heat medium flowing through the circulation system. It is preferable to set the inner diameter of the water pipe. Further, the combustion exhaust gas generated by the combustion reaction is reduced in temperature (about 150 to 200 ° C.), exhausted from the exhaust part 1c, and fed to the convection chamber 2 through the connection path 3 subjected to heat insulation.

  The convection chamber 2 is provided with an exhaust gas flow passage 2a, a lower water pipe group 2b, and a lower exhaust part 2c. The combustion heat of the combustion exhaust gas fed to the convection chamber 2 through the connection path 3 circulates in the lower water pipe group 2b in which a plurality of water pipes are disposed while the combustion exhaust gas circulates in the exhaust gas flow passage 2a. And is absorbed by the adjacent heat medium (a heat medium in the lower heat medium chamber 5, the upper water pipe group 1b, or an intermediate heat medium chamber described later) so as to surround the convection chamber 2. Here, as the water pipe or smoke pipe (hereinafter referred to as “water pipe or the like”) used for the lower water pipe group or the like 2b, it is preferable to use a hollow soot having fins on the outer periphery. The heat transfer area of the fin can be ensured, and the heat exchange efficiency can be further improved. Therefore, the combustion exhaust gas flowing through the exhaust gas flow passage 2a is discharged from the convection chamber 2 via the lower exhaust part 2c in a state where heat is efficiently absorbed (about 70 to 80 ° C.). As described above, in the combustion chamber 1 and the convection chamber 2, the heat of combustion can be absorbed into the heat medium very efficiently by two-stage heat exchange having different functions.

  The decompression steam chamber 4 is formed with a space maintained under a decompression condition (for example, −0.1 MPa). That is, the space filled with the gas phase or liquid phase heat medium in the main unit 10 and the heat exchange unit 20 is decompressed by, for example, a vacuum pump or the like, and the heat of the gas phase is at a temperature lower than the boiling point of the heat medium at normal pressure. It is configured to be able to form a medium. At this time, as described above, most of the combustion heat generated in the combustion chamber 1 includes the amount of heat absorbed in the convection chamber 2 and the heat in the decompression steam chamber 4 through the heat medium from the upper water pipe group 1b. It is transferred to a gas phase heat medium. Further, it has been confirmed that the temperature of the gas phase heat medium has almost no variation from the internal temperature of the upper water pipe group 1b. This is due to the convection effect of the heat medium including the inside of the upper water pipe group 1b. Thus, in the decompression steam chamber 4, the temperature of the heat medium in the decompression condition is normally maintained in a state of being heated to 80 to 90 ° C. (a state of boiling under reduced pressure), and is transferred to the heat exchange unit 20 via the upper communication channel Lu. Be transported.

  The lower heat medium chamber 5 receives the heat medium recirculated from the heat exchange unit 20 via the lower communication flow path Lb, and the combustion heat of the combustion exhaust gas in the exhaust gas flow passage 2a via the partition wall with the convection chamber 2. Absorb. The heat medium received in the lower heat medium chamber 5 is transferred to the lower water pipe group 2 b and the like of the convection chamber 2. The transfer amount of the heat medium flowing through the circulation system is defined by the combustion load factor and the water level of the heat medium inside the upper water pipe group 1b, etc., and the water level of the heat medium inside the upper water pipe group 1b and the water level inside the heat exchange unit 20 The difference is stable at a position where the transfer amount of the heat medium flowing through the circulation system and the flow resistance balance. The water level of the heat medium inside the upper water tube group 1b is estimated to be equivalent to the average water level if it is in a boiled and gas-liquid mixed state. If the combustion load factor increases, the transfer amount of the heat medium flowing through the circulation system increases, the flow resistance increases, and the water level difference also increases.

  Here, in the main unit 10, as illustrated in FIG. 1A, an intermediate heat medium chamber 2d that connects the upper water pipe group 1b and the lower water pipe group 2b, etc., is provided between the combustion chamber 1 and the convection chamber 2. It is preferable. Two-stage heat exchange between the combustion chamber 1 and the convection chamber 2 is performed mainly by the upper water pipe group 1b and the lower water pipe group 2b. At this time, there may be a difference in the heat absorption conditions of the combustion heat depending on the position of these water pipes, etc., and the water pipes etc. are connected so that the heat medium continuously circulates inside the upper water pipe group 1b and the lower water pipe group 2b etc. Then, the difference between the water pipes or between the water pipes may directly affect the efficiency balance of heat exchange or the formation of stepwise heat exchange. An intermediate heat medium chamber S is provided, and the heat recovery function in each stage is clearly divided, and once the heat medium from the lower side is gathered, the temperature of the heat medium is made uniform, and the upper combustion chamber 1 More efficient heat recovery in the upper water pipe group 1b can be ensured.

[Heat exchange unit]
The heat exchange unit 20 includes a space in which two heat exchange units are disposed. Here, the space where the gas phase heat medium exists is the upper heat exchange space 8, and the space where the liquid phase heat medium exists is the lower heat exchange space 9. The second heat exchange unit 6 is disposed in the upper heat exchange space 8, and the first heat exchange unit 7 is disposed in the liquid layer. In the second heat exchanging unit 6 disposed above, a high-temperature (about 80 to 90 ° C.) gas phase heat medium and supply water flowing through the second heat exchanging unit 6 (inlet temperature of about 40 to 50 ° C.) The heat exchange under the high temperature condition (endothermic heat absorption) is performed. The vapor phase heat medium condenses on the surface of the second heat exchanging section 6 while releasing its latent heat, and forms a liquid liquid heat medium in the form of droplets. The liquid phase heat medium is dropped and stored in the lower heat exchange space 9 along the flow of the heat medium flowing down from the upper part of the second heat exchanging unit 6 in a state where the heat medium is expanded to a predetermined size. At this time, the residual liquid droplets on the surface of the second heat exchanging unit 6 hinder the heat transfer function of the second heat exchanging unit 6, and therefore the flow of the gas phase heat medium from above to the lower heat exchanging space 9. The function of promoting the drop of the droplet is effective for improving the heat exchange efficiency of the second heat exchange unit 6.

  Since the gas phase heat medium is always supplied to the upper heat exchange space 8 as long as the main unit operates, the second heat exchange section 6 can have a very stable heat transfer function. Therefore, since the endothermic function of the supplied water is also stabilized, warm water having a very stable temperature can be supplied. Further, the shape and volume of the upper heat exchange space 8 are not limited as long as heat exchange with the gas phase heat medium is performed in the second heat exchange unit 6. The supply water that has absorbed heat in the second heat exchange unit 6 is heated to about 70 to 80 ° C. and supplied as warm water. The heated water is used as hot water for industrial use such as hot water supply for hot water supply or heating. Further, the supply amount of the supply water is adjusted by a pressure increase by a water supply pump (not shown) and a throttle valve (not shown). Moreover, the city water etc. can be used for the water used as supply water.

  In the lower heat exchange space 9, the heat medium flowing through the circulation system including the liquid heat medium condensed in the second heat exchange unit 6 is collected and stored. The first heat exchange unit 7 is disposed in a liquid heat medium (in the liquid layer) of the lower heat exchange space 9. In the 1st heat exchange part 7, since the heat absorption (sensible heat) from the condensate of the heat medium produced | generated in the 2nd heat exchange part 6 becomes main, contact with more heat media is preferable. By immersing the first heat exchange part 7 in the liquid layer, it is possible to efficiently absorb the sensible heat of the heat medium. Further, the structure immersed in the lower heat exchange space 9 having a predetermined volume enables heat exchange under a substantially constant and stable temperature condition, and can sufficiently absorb heat even with a large flow rate of supply water. Therefore, in combination with the stable heat exchange function in the upper heat exchange space 8, a highly stable heat exchange unit 20 can be configured. Furthermore, by giving the 1st heat exchange part 7 a high heat exchange function, the load in the 2nd heat exchange part 6 can be reduced, and the higher heat exchange function can be ensured as the heat exchange unit 20 whole. Moreover, it became possible to comprise the water heater which can respond | correspond to the conditions of various warm water, and a requirement specification by classifying each function clearly about both heat exchangers 6 and 7. FIG.

  In the lower heat exchange space 9, a liquid phase heat medium (upper layer temperature of about 80 to 90 ° C., lower layer temperature of about 40 to 50 ° C.) and supply water (inlet temperature of about 20 to 30 ° C.) flowing through the first heat exchange unit 7. ) Under low temperature conditions (endothermic sensible heat), the absorbed water is heated to about 40 to 50 ° C. and transferred to the second heat exchange unit 6.

  At this time, for the first heat exchange unit 7 immersed in the liquid layer of the heat medium, various types of heat exchangers having high heat exchange efficiency can be used. In addition to high heat exchange efficiency, the second heat exchange unit 6 has a surface on which the gas phase heat medium is easy to condense, allowing rapid aggregation of the generated droplets, and quickly dropping the condensate On the other hand, a configuration capable of making the first heat exchanging portion 7 in the liquid layer a top priority is given to the high heat exchange efficiency. Specifically, not only a U-shaped heat exchanger but also a heat exchanger using a finned water pipe, a plate heat exchanger, and the like can be applied.

  The liquid phase heat medium stored in the lower heat exchange space 9 is transferred to the main unit 10 via the lower communication flow path Lb. At this time, the lower heat exchange space 9 determines and maintains the liquid level of the liquid phase heat medium, and at the same time, moves to the main unit 10 due to the difference in water level between the liquid phase heat medium and the liquid level in the main unit 10 Therefore, a stable heat medium circulation system can be formed.

[Hot heat transfer function with fluid transfer in this water heater]
In this water heater, three fluids are transferred, and warm heat is transferred between the fluids. Specifically, the three fluids are combustion exhaust gas generated in the combustion chamber 1 in the main unit 10, a heat medium circulating between the main unit 10 and the heat exchange unit 20, and supply water heated in the heat exchange unit 20. Is applicable.
(1) In the combustion chamber 1, the combustion exhaust gas is reduced in temperature (about 150 to 200 from the high temperature state immediately after generation (about 700 to 800 ° C.) by exchanging heat in the upper water pipe group 1 b (second stage water pipe group 1 f). In the convection chamber 2 via the upper exhaust part 1 c and the connection path 3. In the convection chamber 2, the temperature is reduced by exchanging heat in the lower water tube group 2 b (about 70 to 80 ° C.), and flows through the exhaust gas flow passage 2 a and is discharged from the lower exhaust part 2 c.
(2) In the combustion chamber 1, the heat medium circulates in the upper water tube group 1b, absorbs combustion heat by heat exchange with the combustion exhaust gas, and is partially heated and vaporized (about 80 to 90 ° C.). Then, it is transferred to the upper heat exchange space 8 through the decompression steam chamber 4 and the upper communication channel Lu. In the upper heat exchange space 8, the temperature is reduced and condensed (about 80 to 90 ° C.) by heat exchange in the second heat exchange unit 6, dropped as a condensate into the lower heat exchange space 9, and stored as a liquid phase heat medium. Is done. The liquid phase heat medium is further subjected to heat exchange in the first heat exchanging unit 7 to be reduced in temperature (about 40 to 50 ° C.). The liquid phase heat medium in the lower heat exchange space 9 is introduced into the convection chamber 2 via the lower communication flow path Lb and the lower heat medium chamber 5, flows through the lower water pipe group 2b, etc., and is exchanged for heat. The temperature is transferred upward (about 45 to 55 ° C.) and flows again through the upper water pipe group 1b (forms a circulating flow).
(3) Supply water (inlet temperature about 20 to 30 ° C.) is circulated and heated to the first heat exchanging section 7 (about 40 to 50 ° C.), and then is circulated and heated to the second heat exchanging section 6 ( About 70-80 ° C.) and supplied as warm water.

<Second configuration example of the hot water heater>
As illustrated in FIG. 2, the water heater is a liquid-phase heat medium that communicates with the upper heat exchange space 8 and the lower heat exchange space 9 in the lower part of the heat exchange unit 20 in the first configuration example. The upper space portion 8a having a space filled with the upper space portion and the lower space portion 9a formed only from the lower heat exchange space 9 are divided into two upper and lower spaces, and the upper space portion 8a and the lower space portion 9a are divided into circulation pumps 9b. (The second configuration example).

  In the first configuration example, a natural circulation system based on a water level difference between the liquid level in the main unit 10 and the liquid level in the heat exchange unit 20 due to the flow resistance of the heat medium is used. In the second configuration example, not only such a water level difference but also a condition in which a desired transfer amount of the heat medium cannot be sufficiently secured can be accommodated, in the heat medium circulation system, not only the water level difference but also the heat exchange unit 20 A circulation pump 9b was disposed in the liquid layer of the heat medium to constitute a forced circulation system having a forced heat medium transfer capability. Specifically, when the combustion load factor increases rapidly, such a water level difference may not always follow. Even if there is a change in the operating conditions of the water heater, the heat medium circulation function can be improved, and the heat exchange function can be enhanced and the combustion heat of the combustion exhaust gas can be recovered with higher efficiency. At this time, the circulation pump 9b is operated according to the liquid level position detected by the liquid level detector S provided in the upper space part 8a of the heat exchange unit 20, and prevents the water level from rising in the upper space part 8a. As the liquid level detector S, an ultrasonic type, an electrode type, or the like can be used.

DESCRIPTION OF SYMBOLS 10 Main body unit 20 Heat exchange unit 1 Combustion chamber 1a Combustion burner 1b Upper water pipe group 1c Upper exhaust part 1d Flame 1e Front stage water pipe group 1f Rear stage water pipe group 2 Convection chamber 2a Exhaust gas flow path 2b Lower water pipe group etc. 2c Lower exhaust part 2d Intermediate heat Medium chamber 3 Connection path 4 Depressurized steam chamber 5 Lower heat medium chamber 5b Circulation pump 6 Second heat exchange part 7 First heat exchange part 8 Upper heat exchange space 8a Upper space part 9 Lower heat exchange space 9a Lower space part 9b Circulation pump S Liquid level detector Lu Upper communication flow path Lb Lower communication flow path

Claims (4)

A combustion chamber provided with a combustion burner, an upper water pipe group, and an upper exhaust part; a convection chamber provided below the combustion chamber; and provided with an exhaust gas flow passage and a lower water pipe group or a smoke pipe group and a lower exhaust part; A connection path connecting the upper exhaust part and the exhaust gas flow passage, disposed in an upper part of the combustion chamber, a decompression steam chamber connected to the upper water pipe group, and disposed in a lower part of the convection chamber, A lower heat medium chamber connected to the lower water pipe group or the smoke pipe group, and a main body unit comprising:
An upper heat exchange space that communicates with the decompression steam chamber through an upper communication channel and that is filled with a gas phase heat medium, and a lower portion that communicates with the lower heat medium chamber and a lower communication channel and that is filled with a liquid phase heat medium. A heat exchange unit in which a heat exchange space is formed, a second heat exchange unit is disposed in the upper heat exchange space, and a first heat exchange unit is disposed in the lower heat exchange space;
A vacuum water heater characterized by comprising:   2. The vacuum type according to claim 1, wherein the main body unit includes an intermediate heat medium chamber connecting the upper water pipe group and the lower water pipe group or the smoke pipe group between the combustion chamber and the convection chamber. Water heater.   The interior of the heat exchange unit is composed of an upper space portion having a space filled with a part of a liquid phase heat medium communicating with the lower heat exchange space and the lower heat exchange space, and the lower heat exchange space. The vacuum water heater according to claim 1 or 2, wherein the lower space portion to be formed is divided into two upper and lower spaces, and the upper space portion and the lower space portion are connected by a circulation pump. The flue gas generated in the combustion chamber is reduced in temperature by exchanging heat in the upper water pipe group, introduced into the convection chamber through the upper exhaust part and the connection path, and heated in the lower water pipe group or the smoke pipe group. The temperature is reduced by exchanging, passing through the exhaust gas flow passage, and discharged from the lower exhaust part,
A heat medium filling the inside of the upper water pipe group absorbs combustion heat by heat exchange with the combustion exhaust gas, and a part of the heat medium is heated and vaporized, and is transferred to the upper heat exchange space through the vacuum steam chamber. The temperature is reduced and condensed by exchanging heat in the second heat exchanging unit, dripped into the lower heat exchange space as a condensate, and circulates in the lower water tube group or the smoke tube group through the lower heat medium chamber. Heat exchange and heating, transferred upward, and circulating through the upper water tube group through the intermediate heat medium chamber, forming a circulation flow,
The vacuum water heater according to any one of claims 1 to 3, wherein supply water is circulated from the first heat exchange section to the second heat exchange section and supplied as warm water.

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