JP2013029286A - Water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable desired heated water to be supplied by efficiently recovering combustion heat of combustion exhaust gas discharged from a combustion burner provided in a water heater using a heating medium of a circulation system, and the rise of temperature/pressure to be prevented inside the water heater, and low temperature corrosion or the like accompanying cooling of the combustion exhaust gas further to be prevented.SOLUTION: The water heater includes: a body unit 10 having a combustion chamber 1 provided with a combustion burner 1d and a water pipe group 1b in which the heating medium for absorbing the combustion heat is distributed; and a heat exchange unit 20 having a lower heat exchange space 6 and an upper heat exchange space 7 for performing heat exchange of the heating medium which has absorbed the heat and supply water distributed from the first heat exchange part 7 to the second heat exchange part 6. The bypass flow rate of the supply water to bypass the first heat exchange part 7 is adjusted.

Description

  The present invention relates to a water heater, and is useful, for example, as a vacuum water heater or a pressureless water heater which is an industrial hot water generator.

  Conventionally, various types of industrial hot water generators have been used, but vacuum water heaters and non-pressure hot 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. 5 (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 above-described vacuum water heater or non-pressure water heater may have the following problems and problems.
(I) In the conventional vacuum water heater, the temperature of the heat transfer water is normally maintained in a state heated to 80 ° C. to 90 ° C., and the cold water is heat-exchanged with the hot water in the heat exchanger of the vacuum 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) On the other hand, the combustion exhaust gas that is heat-exchanged with the heat medium that forms a circulation system with heating-cooling contains moisture near saturation, which generates a large amount of condensed water due to the temperature reduction and cooling of the combustion exhaust gas. Accordingly, there is a risk that white smoke is generated when the fuel is gas-fired such as city gas, and low-temperature corrosion is caused when oil is burned such as heavy oil (hereinafter referred to as “low-temperature corrosion”). In particular, in order to recover the combustion heat more efficiently, it is preferable to cool the combustion exhaust gas as much as possible. Therefore, it is necessary to control the temperature of the combustion exhaust gas or the heat medium that does not cause low-temperature corrosion or the like in the case of oiling.

  An object of the present invention is to use a circulating heat medium, efficiently recover the combustion heat of the combustion exhaust gas discharged from the combustion burner provided in the water heater, and supply the desired warming water. An object of the present invention is to provide a water heater capable of preventing low temperature corrosion and the like accompanying cooling of combustion exhaust gas while maintaining high combustion efficiency.

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

  The water heater according to the present invention includes a combustion chamber provided with a combustion burner and a water tube group through which a heat medium flows, an upper flow passage disposed at an upper portion of the combustion chamber and connected to the water tube group, A main unit including a lower flow passage disposed below the combustion chamber and connected to the water pipe group, and an upper heat exchange that communicates with the upper flow passage and the upper communication flow path so that a high-temperature heat medium flows down A space, a lower heat exchange space that communicates with the lower flow passage and the lower communication channel, and a low-temperature heat medium flows therethrough, and a second heat exchange portion is disposed in the upper heat exchange space, A first heat exchange part is disposed in the lower heat exchange space, and supply water supplied to the introduction flow path to the first heat exchange part passes through the connection flow path from the first heat exchange part. Hot water that is circulated through the second heat exchange section and is supplied as warm water from the supply passage of the second heat exchange section And road is branched from the introduction flow path, and having a heat exchange unit and a bypass passage which is connected to the connecting channel.

  As described above, in the hot water generator, efficient recovery of the combustion heat of the combustion exhaust gas becomes a major issue. Moreover, it becomes a subject to produce warm water efficiently using the heat of the used heat medium. In the recovery of combustion heat, the main body unit is provided with a water tube group to perform heat exchange between the combustion exhaust gas and the heat medium used for recovery, and in the heat exchange unit, supply water to be heated and heated. And heat exchange of both fluids countercurrently in each stage, so that the heat of the heat medium can be absorbed into the feed water and very high heat exchange efficiency can be obtained. I found it. That is, in the heat exchange unit, the high-temperature heat medium heated in the main body unit is caused to flow downward from above, and the second heat exchange unit is disposed above and the first heat exchange unit is disposed below to provide low-temperature supply water. The heat from the lower side to the upper side and heat is exchanged countercurrently in each heat exchange part, thereby recovering the heat of the heat medium very efficiently and taking out the hot water from the upper second heat exchange part Made possible. Here, the “water pipe group” refers to a configuration having a high heat exchange function in which a plurality of water pipes or smoke pipes are arranged, through which a heat medium can flow.

In addition, the present invention is characterized in that a bypass flow path capable of adjusting and controlling the amount of water supplied to the first heat exchange unit is provided. This has the following technical significance for the main body unit, the heat exchange unit, and the water heater as a whole.
(I) When the temperature of the heat medium returned to the main unit is low, there is a risk of low temperature corrosion or the like accompanying the generation of a large amount of condensed water in heat exchange with the combustion exhaust gas in the main unit. Since the heat exchange in the first heat exchange unit is affected by the temperature condition of the feed water, when the feed water temperature is low, a part of the feed water is bypassed or the bypass flow rate is increased to increase the first heat. By reducing the flow rate of the supply water introduced into the exchange unit, it is possible to suppress low temperature corrosion and prevent low temperature corrosion and the like.
(Ii) In the whole water heater, for example, when starting the cold can, the supply water is not introduced into the first heat exchange unit, but is introduced into the second heat exchange unit via the bypass channel, The temperature rise of the heat medium can be accelerated, and the water heater can be started up efficiently. Thereafter, by gradually increasing the amount of water supplied to the first heat exchange section, the combustion heat of the combustion exhaust gas can be efficiently recovered, and the generation of condensed water of the combustion exhaust gas at the start of the cold can can be reduced. It becomes possible.

The present invention is the above-mentioned water heater, wherein the flue gas generated in the combustion chamber is heat-exchanged with the heat medium in the water tube group, is reduced in temperature, is discharged from an exhaust part, and fills the inside of the water tube group A heat medium absorbs combustion heat by heat exchange with the combustion exhaust gas, is heated, transferred to the upper heat exchange space through the upper flow passage, and reduced by heat exchange in the second heat exchange section. Heated and flowed down to the lower heat exchanging space, heat exchanged in the first heat exchanging part and reduced in temperature, and a circulation flow is formed and circulated through the water pipe group through the lower flow passage, and supplied Water is circulated through the first heat exchange unit and the second heat exchange unit, heated and supplied as warm water, and an output of a temperature sensor provided in the lower communication channel is input, Brakes the control valve provided in the hot water flow path or the bypass flow path The control unit, characterized in that the flow rate of feed water to be circulated in the bypass passage is adjusted.
In the water heater, two-stage heat exchange is performed in which the heat generated in the combustor is absorbed by the heat medium, and further, the supply water is absorbed through the heat medium. At this time, the present invention verifies how combustion heat exhaust gas, heat medium, and heat absorption side feed water that is a heat transfer medium can be circulated to make maximum use of heat, combustion exhaust gas, heat medium, It has been found that heated water can be taken out from the supplied water in an extremely efficient and stable manner by forming the circulation of the supplied water as described above. Also, in the heat exchange between the heat medium and the combustion exhaust gas, the temperature control of the heat medium returning to the main unit is important in order to prevent low temperature corrosion etc. in the main unit due to the generation of a large amount of condensed water. By increasing the flow rate and decreasing the flow rate of the feed water introduced into the first heat exchange section, it has become possible to prevent low temperature corrosion and the like by suppressing the temperature of the refluxed heat medium from being lowered.

The present invention is the water heater as described above, wherein the first heat exchange unit is configured by a plurality of heat exchange units arranged in series, and a connection part of each heat exchange unit is branched and connected to the bypass flow path. In addition, the flow rate of the feed water to be circulated through the first heat exchange unit is adjusted.
As described above, the prevention of the generation of condensed water in the main unit is particularly important in the long-term use of oil-fired water heaters such as heavy oil. On the other hand, since the generation of condensed water is also caused by a short-time decrease in the combustion exhaust gas temperature, the temperature control of the heat medium returned to the main unit that exchanges heat with the combustion exhaust gas is particularly required to be quick. In the present invention, the first heat exchanging unit is configured by a plurality of heat exchanging units having a bypass flow path, and heat exchange between the supply water supplied to the first heat exchanging unit, in particular, the combustion exhaust gas and the heat medium is performed. By adjusting and controlling the amount of water supplied to the heat exchange unit close to the site, the temperature stability of the heat medium can be secured quickly.

The present invention is the above-mentioned water heater, wherein the main body unit constitutes a pressureless water heater, and the heat medium in the liquid phase heated in the water pipe group is supplied to the upper heat passage through the upper flow passage. It is transferred to the exchange space, is heat-reduced by the second heat exchanging part, is reduced in temperature, flows down to the lower heat exchanging space, is heat-exchanged in the first heat exchanging part, is reduced in temperature, and passes through the lower flow passage A circulation flow of a heat medium having the same phase that circulates through the water tube group is formed.
As described above, according to the present invention, in the heat exchange unit, the high-temperature heat medium heated in the main body unit is caused to flow down, and the second heat exchange unit is disposed on the upper side and the first heat exchange unit is disposed on the lower side. The flow rate of the feed water supplied to the first heat exchanging unit by providing a flow path for bypassing the first heat exchanging unit while allowing the feed water to flow from the lower side to the upper side and exchanging heat in each heat exchange unit countercurrently. By adjusting, it was possible to improve the recovery efficiency of the heat of the heat medium, and to adjust the temperature of the heat medium returned to the main unit to prevent low temperature corrosion due to condensation of combustion exhaust gas. In particular, the function of supplying a high-temperature heat medium from above and recovering a low-temperature heat medium from below in the heat exchange unit prevents the occurrence of a backflow of heat inside the in-phase heat medium and maintains the natural flow of heat. Therefore, it is very effective for a pressureless water heater that is characterized in that a circulation flow of a heat medium in the same phase is formed.

The present invention is the above-mentioned water heater, wherein the lower communication flow path includes a heat recovery unit, and combustion exhaust gas generated in the combustion chamber of the main body unit and heat that is circulated from the heat exchange unit to the lower communication flow path The heat exchange with the medium is performed.
Heat exchange between different phases, such as combustion exhaust gas and heat medium, is performed in multiple stages, and by sequentially performing a predetermined temperature control, combustion heat can be recovered with higher efficiency. In the present invention, the main body unit constituting the pressureless water heater should be heat-exchanged and the combustion exhaust gas already lowered in temperature, and the heat-exchange unit already heat-reduced and lowered in temperature, and then heated in the main body unit. By providing a heat recovery section that exchanges heat countercurrently with the heat medium (lower than the combustion exhaust gas temperature), the heat absorption from the combustion exhaust gas and the supply of the heat to the heat medium are promoted. At the same time, it has become possible to prevent the low temperature corrosion of the combustion exhaust gas and prevent low temperature corrosion.

The present invention is the above-mentioned water heater, wherein the main unit constitutes a decompression water heater, has a combustion burner and an upper exhaust part, and is provided with an upper water tube group in which a heat medium flows. And a lower water pipe group disposed below the combustion chamber, having an exhaust gas flow path and a lower exhaust part, and through which a heat medium flows and connected to the upper water pipe group and the lower flow path. A convection chamber, a connection path connecting the upper exhaust part and the exhaust gas flow passage, a decompression steam chamber disposed at an upper portion of the combustion chamber and connected to the upper water pipe group and the upper flow passage, And the heat exchange unit communicates with the decompression steam chamber through the upper flow passage in the upper communication flow path, and is filled with a gas phase heat medium, and through the lower flow passage. The lower water pipe group communicates with the lower communication channel, and the liquid phase heat medium is Together with the lower heat exchanger space is formed to be Tasa, the second heat exchanger to the upper heat exchanger space, wherein the first heat exchange unit to the lower heat exchanger space, characterized in that it is arranged.
As described above, at the time of recovery of combustion heat, the heat exchange unit performs heat exchange in two stages between the heat medium and the water to be heated, and heats both fluids countercurrently in each stage. It has been found that a very high heat exchange efficiency can be obtained. The present invention further improves the heat exchange efficiency by applying the same technical idea to the main unit. 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.

  Further, 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. Furthermore, the amount of transfer of the heat medium that circulates in the circulation system is estimated to correspond 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 in a gas-liquid mixed state). The water level difference between the main unit and the heat exchange unit is defined by the distribution resistance of the entire system, and the water level of each unit is a position where the transfer amount of the heat medium flowing through this circulation system and the distribution resistance are balanced. It stabilizes at. Here, the “combustion load factor” refers to the ratio of the actual combustion amount to the rated combustion amount.

Overall configuration diagram showing a basic configuration example (first configuration example) of a water heater according to the present invention Overall configuration diagram showing a second configuration example of a pressureless water heater according to the present invention Overall configuration diagram showing a third configuration example of a vacuum water heater according to the present invention Whole block diagram which shows the 4th structural example of the vacuum type water heater which concerns on this invention Overall configuration diagram illustrating the outline of a vacuum hot water boiler according to the prior art

  A water heater according to the present invention (hereinafter referred to as “the present water heater”) includes the following main body unit and heat exchange unit. The main body unit is provided with a combustion chamber provided with a combustion burner and a water tube group, an upper flow passage disposed at an upper portion of the combustion chamber and connected to the water tube group, and disposed below the combustion chamber and connected to the water tube group. The heat exchange unit communicates with the upper flow passage through the upper communication flow path, and communicates through the upper heat exchange space through which the high-temperature heat medium flows down, and communicates through the lower flow passage and the lower communication flow path. A lower heat exchange space in which a low-temperature heat medium flows, and a second heat exchange portion is disposed in the upper heat exchange space, and a first heat exchange portion is disposed in the lower heat exchange space, Supply water supplied to the introduction flow path to the first heat exchange section is circulated from the first heat exchange section to the second heat exchange section via the connection flow path, and added from the supply flow path of the second heat exchange section. A hot water channel provided as hot water, and a bypass channel branched from the introduction channel and connected to the connection channel. Obtain.

At this time, the fluid constituting the water heater is formed from combustion exhaust gas, heat medium and supply water, and has the following distribution function and heat balance function.
(I) The combustion exhaust gas is generated in the combustion chamber in the main unit, is heat-exchanged with the heat medium in the water tube group, is reduced in temperature, and is discharged from the exhaust section.
(Ii) In the main unit, the heat medium fills the interior of the water tube group, absorbs the heat of combustion by heat exchange with the combustion exhaust gas, and is heated to enter the upper heat exchange space of the heat exchange unit through the upper flow path. Be transported. In the heat exchange unit, the temperature is reduced by exchanging heat in the second heat exchanging part and flowing down to the lower heat exchanging space, the temperature is lowered by exchanging heat in the first heat exchanging part, Circulates inside the water tube group. A circulation flow is formed across the main unit and the heat exchange unit.
(Iii) Supply water is circulated to the first heat exchange unit and the second heat exchange unit in the heat exchange unit, heated and supplied as warm water, and an output of a temperature sensor provided in the lower communication channel Is input, and the flow rate of the feed water to be circulated through the bypass channel is adjusted by a control unit that brakes a control valve provided in the hot water channel or the bypass channel.
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. 1 (first configuration example). This water heater constitutes a pressureless water heater, and the main unit 10 and the heat exchanging unit 20 are communicated with each other through an upper flow passage Tu-upper communication passage Lu and a lower communication passage Lb-lower flow passage Tb. The main unit 10 is transferred to the heat exchange unit 20 via the upper flow passage Tu-upper communication passage Lu, and is transferred from the heat exchange unit 20 to the main body unit 10 through the lower communication passage Lb-lower flow passage Tb. The By such a cyclic movement of the heat medium, efficient heat transfer can be performed. The main unit 10 has a combustion chamber 1 which is a source of heat and is a primary heat transfer field, and the heat exchange unit 20 is a discharge end of heat and has a secondary heat transfer. It has the 2nd heat exchange part 6 which is a field, the 1st heat exchange part 7 which is a field of tertiary heat transfer, and forms the upper heat exchange space 8 and the lower heat exchange space 9 which are the places of heat transfer. Furthermore, in the heat exchange unit 20, part or all of the supplied water that is circulated from the first heat exchange unit 7 to the second heat exchange unit 6 and is supplied as warm water bypasses the first heat exchange unit 7. A bypass flow path B is provided so that the second heat exchange unit 6 can be supplied. The flow rate of the feed water flowing through the bypass flow path B (hereinafter referred to as “bypass flow rate”) is the temperature of the heat medium flowing through the lower communication flow path Lb (specifically, the temperature sensor S installed in the flow path). The control valve V is controlled and adjusted by the control unit 5 using the output) as an index. Here, water such as city water is usually used as the heat medium. The liquid phase heat medium forming the circulation system in the water heater is transferred in phase by the circulation pump P.

  In this water heater, two-stage heat exchange is performed in which the heat generated in the combustor 1 is absorbed by the heat medium, and further, the supply water is absorbed through the heat medium. Further, also in the stage of transferring the heat from the heat medium to the supply water, the heat exchange unit 20 performs two-stage heat exchange countercurrently. Specifically, heat exchange of the high-temperature condition heat medium and supply water in the second heat exchange unit 6 disposed above, and heat of the low-temperature condition in the first heat exchange unit 7 disposed below. Heat exchange between the medium and the feed water takes place. In other words, the heating medium heating function that forms the heat energy circulation system and the AC heat exchange function with the supply water by the heating medium make the maximum use of the combustion heat as the heat source of the water heater. The thermal efficiency of the water heater can be improved.

[Main unit]
As illustrated in FIG. 1, the main unit 10 is provided with a combustion chamber 1 provided with a combustion burner 1a, a water tube group 1b, and an exhaust part 1c. 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 water tube group 1b in which a plurality of water tubes are arranged. That is, the combustion heat of the combustion exhaust gas is absorbed mainly through the water tube group 1 b, and the radiant heat energy of the flame 1 d is absorbed through the water cooling wall of the combustion chamber 1. As described above, by appropriately disposing the water cooling wall of the combustion chamber 1 and the water tube group 1b in the combustion chamber 1, heat can be efficiently absorbed.

  At this time, most of the combustion heat generated in the combustion chamber 1 is transferred to the heat medium inside the water tube group 1 b or the outer peripheral portion of the water cooling wall of the combustion chamber 1. In this way, the temperature of the heat medium is normally maintained in a state of being heated to 80 to 90 ° C., and is transferred to the heat exchange unit 20 via the upper flow passage Tu and the upper communication flow passage Lu. Further, the combustion exhaust gas generated by the combustion reaction is reduced in temperature (about 150 to 200 ° C.) and exhausted from the exhaust part 1c. On the other hand, the heat medium is refluxed from the heat exchange unit 20 to the main unit 10 via the lower communication flow path Lb and the lower flow path Tb. The accepted heat medium is transferred to the water tube group 1b of the combustion chamber 1 to form a circulation system. The amount of transfer of the heat medium flowing through the circulation system is adjusted by the circulation pump P.

[Heat exchange unit]
The heat exchange unit 20 includes a space in which two heat exchange units are disposed. Here, the space where the heat medium under the high temperature condition exists is referred to as the upper heat exchange space 8, and the space where the heat medium under the low temperature condition exists is referred to as 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 lower heat exchange space 9. In the second heat exchanging unit 6 disposed above, heat exchange is performed on the high-temperature condition of the feed water flowing through the inside of the second heat exchanging unit 6 with the high-temperature heat medium. The heat medium flows down from the second heat exchange unit 6 to the lower heat exchange space 9 and is stored. The city water or the like can be used as the water used as the supply water.

  In addition, in the heat exchange unit 20, the supply water supplied to the introduction flow path Wa to the first heat exchange unit 7 is transferred from the first heat exchange unit 7 to the second heat exchange unit 6 through the connection flow path Wb. A warm water flow path W that is circulated and is supplied as heated water from the supply flow path Wc of the second heat exchange unit 6, and a bypass flow path B that is branched from the introduction flow path Wa and connected to the connection flow path Wb. The bypass flow rate is adjusted by the control unit 5 that is provided and brakes the control valve V provided in the hot water flow path W or the bypass flow path B. The bypass flow rate uses the output of the temperature sensor S provided in the lower communication flow path Lb as an index, and the temperature of the heat medium returned to the main unit 10 is within a predetermined range (for example, about 45 to 55 ° C. in the case of gas firing). In the case of oiling, the temperature is controlled to be about 55 ° C. When the supply water supplied to the 1st heat exchange part 7 is low temperature, generation | occurrence | production of the low temperature corrosion etc. accompanying generation | occurrence | production of a large amount of condensed water by cooling of the combustion exhaust gas in the main body unit 10 can be prevented. It is possible to adjust the fluctuation factors such as the temperature condition of the supply water and the temperature condition of the warming water with respect to the main body unit 10 to ensure stable heat exchange efficiency and to prevent the occurrence of low temperature corrosion or the like. Thus, it became possible to comprise the water heater which can respond to the conditions and required specifications of various warm water by having each different function about both heat exchangers 6 and 7. FIG.

  Since the constant-temperature heat medium is always supplied to the upper heat exchange space 8 as long as the main unit 10 operates, the second heat exchange unit 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 heat medium is efficiently 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, in the present water heater, the supply amount of the supply water is adjusted by the circulation pump P, but a combination of a booster pump and a throttle valve or a proportional valve is also possible.

As for the control valve V that adjusts the bypass flow rate, FIG. 1 illustrates a three-way valve that can change the ratio of the supply flow rate to the first heat exchange unit 7 and the bypass flow rate, but is not limited to this, and has various configurations. Applicable. For example, as illustrated in FIG. 2A, valves (open / close valves or control valves) V1 and V2 are disposed in the supply flow path to the first heat exchange unit 7 and the bypass flow path B, and each flow rate is adjusted. A configuration to adjust is possible. Specifically, the following configurations and functions can be given.
(A) The on-off valves V1 and V2 are provided, and one of them is opened and the other is closed, and each flow path is switched to adjust the bypass flow rate. The opening / closing time of each on-off valve V1, V2 is determined using the output of the temperature sensor S as an index.
(B) The on-off valves V1 and V2 are provided, the normal on-off valve V1 is opened to supply water to the first heat exchange unit 7, and the bypass flow rate is adjusted by opening and closing only the on-off valve V2. When more bypass flow is required, the on-off valve V2 is opened and only the on-off valve V1 is opened and closed to adjust the bypass flow. The opening / closing time of each on-off valve V1, V2 is determined using the output of the temperature sensor S as an index.
(C) Control valves V1 and V2 are provided, and the opening degree (including closing) of the control valve V1 is adjusted to control the amount of water supplied to the first heat exchange unit 7, and the opening degree of the control valve V2 is adjusted. To control the bypass flow rate. The opening degree of each control valve V1, V2 is determined using the output of the temperature sensor S as an index.
The supply water supplied to the introduction flow path Wa is circulated to the connection flow path Wb via the valve V1 and the first heat exchange unit 7, and is also circulated to the connection flow path Wb via the bypass flow path B and the valve V2. Are collected and distributed to the second heat exchange unit 6. The bypass flow rate uses the output of the temperature sensor S provided in the lower communication flow path Lb as an index, and the temperature of the heat medium returned to the main unit 10 is within a predetermined range (for example, about 45 to 55 ° C. in the case of gas firing). In the case of oiling, the temperature is controlled to be about 55 ° C. The supply water circulated through the second heat exchange unit 6 is supplied as heated water from the supply flow path Wc.

Moreover, the 1st heat exchange part 7 is arrange | positioned in series so that adjustment / control of the bypass flow volume by which the flow volume of the supply water distribute | circulated to the 1st heat exchange part 7 is adjusted may be illustrated in FIG.2 (B). It is possible to carry out by a configuration in which a plurality of (two) heat exchange units 7a and 7b are connected, and a connection portion of each heat exchange unit 7a and 7b is branched (branch channel Ba) and connected to the bypass channel B. It is. Note that the number of heat exchange units is not limited to two, and can be increased according to control accuracy (the number of branch channels is the same). Since the generation of condensed water is also caused by a short-term decrease in the temperature of the combustion exhaust gas, the temperature control of the heat medium returned to the main unit that exchanges heat with the combustion exhaust gas is required to be particularly quick. About two functions which the 1st heat exchange part 7 has,
(I) The heat exchange unit 7b is mainly responsible for the preheating function of the supply water supplied to the second heat exchange unit 6, and (ii) the heat exchange unit 7a is responsible for the temperature control function of the heat medium returned to the main unit. As a result, it is possible to effectively collect the heat and to quickly ensure the stability of the temperature of the heat medium. Specifically, valves (open / close valves or control valves) V1, V2, and V3 are disposed in the supply flow path Wd, the branch flow path Ba, and the bypass flow path B to the first heat exchange unit 7, and the following configuration is provided. -Can list functions.
(A) Open / close valves V1 to V3 are provided, one of them is opened and the other is closed to switch the respective flow paths, and only the amount of water supplied through the first heat exchange unit 7 and the heat exchange unit 7b are passed. Adjust water supply and bypass flow rate. The opening / closing time of each on-off valve V1 to V3 is determined using the output of the temperature sensor S as an index.
(B) The on-off valves V1 to V3 are provided, and only the normal on-off valve V1 is opened to supply water to the first heat exchange unit 7, and when only the heat exchange unit 7b is supplied, only the on-off valve V3 is opened. When the total amount is bypassed, only the on-off valve V2 is opened to adjust the amount of water supplied to the first heat exchange unit 7 (bypass flow rate). The opening / closing time of each on-off valve V1 to V3 is determined using the output of the temperature sensor S as an index.
(C) Control valves V1 to V3 are provided, and the opening (including closing) of the control valve V1 is adjusted to control the amount of water supplied to the first heat exchange unit 7, and the opening of the control valve V2 is adjusted. To control the bypass flow rate. At the same time, the amount of water supplied to the heat exchange unit 7b is controlled by adjusting the opening of the control valve V3. The opening degree of each control valve V1 to V3 is determined using the output of the temperature sensor S as an index.
The supply water supplied to the introduction flow path Wa is (i) the valve V1, the first heat exchange unit 7 (heat exchange unit 7a and heat exchange unit 7b), and (ii) the branch flow path Ba, valve V3, heat exchange unit. 7b, (iii) One of the three flow paths of bypass flow path B and valve V2, or some of them, are circulated to the connection flow path Wb, and are collected and circulated to the second heat exchange section 6. . The bypass flow rate flowing through the bypass flow path B and the branch flow path Ba is based on the output of the temperature sensor S provided in the lower communication flow path Lb, and the temperature of the heat medium returned to the main unit 10 is within a predetermined range. (For example, it is about 45-55 degreeC in the case of gas-fired, and about 55 degreeC in the case of oil-fired.). The ratio of the adjusted bypass flow rate that flows through the bypass flow path B and the branch flow path Ba is controlled by the temperature and flow rate of the feed water. The supply water circulated through the second heat exchange unit 6 is supplied as heated water from the supply flow path Wc.

  In the lower heat exchange space 9, heat exchange is performed between a low-temperature heat medium (exit temperature of about 45 to 60 ° C.) and supply water (inlet temperature of about 20 to 30 ° C.) flowing through the inside of the first heat exchange unit 7. The supplied water is heated and transferred to the second heat exchange unit 6. The heat medium in the lower heat exchange space 9 is transferred to the main unit 10 via the lower communication flow path Lb and the lower flow path Tb. At this time, when the inlet temperature of the feed water becomes low and the temperature of the liquid phase heat medium falls below a predetermined temperature (for example, about 45 to 55 ° C. for gas-fired and about 55 ° C. for oil-fired) Controlled to increase the feedwater bypass flow rate. The temperature of the heat medium can be increased by reducing the heat absorbed by the first heat exchange unit 7. The control temperature is set to a different value depending on the configuration of the water heater, for example, the difference between the non-pressure type and the vacuum type, or the difference in fuel such as gas burning and oil burning. An optimum temperature is set in order to effectively collect the heat and prevent the occurrence of low temperature corrosion or the like.

[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 from the high temperature state immediately after generation (about 700 to 800 ° C.) through heat exchange in the water tube group 1b (about 150 to 200 ° C.). Discharged.
(2) In the combustion chamber 1, the heat medium circulates in the water tube group 1b, absorbs the combustion heat by heat exchange with the combustion exhaust gas, and partially heats (about 80 to 90 ° C.). It is transferred to the upper heat exchange space 8 via the passage Tu-upper communication passage Lu. In the upper heat exchange space 8, the temperature is reduced by exchanging heat in the second heat exchange unit 6, flows down to the lower heat exchange space 9, and further heat-exchanged in the first heat exchange unit 7 to be reduced in temperature (about 45 ~ 60 ° C). The heat medium under the low temperature condition in the lower heat exchange space 9 flows through the inside of the water tube group 1b through the lower communication flow path Lb and the lower flow path Tb, exchanges heat, is heated, and is transferred upward (about 80 ~ 90 ° C), forming a circulating flow.
(3) Supply water (inlet temperature about 20 to 30 ° C.) is circulated and heated to the first heat exchange unit 7 and then circulated and heated to the second heat exchange unit 6 (about 70 to 80 ° C.). Supplied as warm water. At this time, when the inlet temperature of the feed water is, for example, 5 ° C. or less, the temperature of the heat medium returned to the main unit 10 is a predetermined temperature (for example, about 45 to 55 ° C. in the case of gas firing, and in the case of oil firing). When the temperature is lower than about 55 ° C., the supply water bypass flow rate is increased and controlled to a desired temperature.

<Second configuration example of the hot water heater>
As illustrated in FIG. 2, the water heater includes a heat recovery unit E in the lower communication flow path Lb, and the combustion exhaust gas generated in the combustion chamber 1 of the main unit 10 and the heat exchange unit 20 to the lower communication flow path Lb. It is preferable to perform heat exchange with the circulating heat medium (second configuration example). Combustion exhaust gas in water tube groups that are likely to have low temperature corrosion or have a large effect due to gradual temperature reduction of the combustion exhaust gas while at the same time promoting the absorption of thermal heat from the combustion exhaust gas and the supply of heat to the heat medium The load of heat exchange with the heat medium can be reduced, and low temperature corrosion and the like can be prevented. Hereinafter, description of matters common to the first configuration example may be omitted.

  Specifically, in the heat recovery part E provided in the lower communication flow path Lb, the temperature of the combustion exhaust gas (about 150 to 200 ° C.) reduced in temperature in the main unit 10 and the heat exchange unit 20 are reduced. A heat medium (about 45 to 60 ° C.) controlled to a predetermined temperature is introduced. It is possible to supply warm heat (recirculation) to the main unit 10 through the heat medium and to reduce the temperature of the combustion exhaust gas stepwise. In particular, when used in conjunction with the control of the bypass flow rate of the feed water, the temperature of the exhaust gas in the heat recovery section E is prevented from excessively decreasing, that is, the occurrence of low-temperature corrosion and the like, and the heating medium heated to the main unit 10 is heated. Therefore, effective use of the heat in the main unit 10 can be achieved.

<The 3rd structural example of this water heater>
The present water heater can constitute a vacuum water heater as illustrated in FIG. 3 in place of the pressureless water heater in the first configuration example (third configuration example). Hereinafter, description of matters common to the first configuration example may be omitted.

  The main body unit 10 includes a combustion chamber 1 having a combustion burner 1d and an upper exhaust part 1c, and an upper water pipe group 1b through which a heat medium circulates, and an exhaust gas flow path disposed below the combustion chamber 1. 2a and a lower exhaust part 2c, a convection chamber 2 provided with a lower water pipe group 2b connected to the upper water pipe group 1b and the lower flow path Tb through which a heat medium flows, and an upper exhaust part 1c and an exhaust gas flow A connection path 3 that connects the path 2a, and a decompression steam chamber 4 that is disposed above the combustion chamber 2 and is connected to the upper water pipe group 1b and the upper flow passage Tu.

  In the heat exchanging unit 20, an upper heat exchange space 8 filled with a vapor phase heat medium is communicated with the decompression steam chamber 4 via the upper flow passage Tu and the upper communication flow passage Lu, and a lower portion via the lower flow passage Tb. A lower heat exchange space 9 is formed which communicates with the water tube group 2b through the lower communication flow path Lb and is filled with a liquid phase heat medium. The second heat exchange section 6 and the lower heat exchange space 9 are formed in the upper heat exchange space 8. The 1st heat exchange part 7 is arrange | positioned. Supply water is distribute | circulated from the 1st heat exchange part 7 to the 2nd heat exchange part 6, and is supplied as heating water. At this time, in this water heater, a bypass flow path B is provided so that a part or all of the supplied water can be supplied to the second heat exchange unit 6 by bypassing the first heat exchange unit 7. The bypass flow rate is adjusted by controlling the control valve V by the control unit 5 using the output of the temperature sensor S provided in the lower communication flow path Lb as an index. While ensuring the stable heat exchange efficiency, generation | occurrence | production of low temperature corrosion etc. can be aimed at.

  At this time, a boundary between the gas phase and the liquid phase of the heat medium is formed in the main body unit 10 and the heat exchange unit 20, and the main body unit is generated by the flow resistance generated by the combustion heat in the flow path of the heat medium in the main body unit 10. A water level difference is generated between the heat exchange unit 10 and the heat exchange unit 20. Using such a water level difference, it is possible to form a natural circulation system by gravity without using the circulation pump P as in the non-pressure type water heater. 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 unit 10 and the heat exchange unit 20 is stabilized at a position where the transfer amount of the heat medium flowing through the circulation system and the flow resistance are balanced. 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.

[Main unit]
In the main unit 10, in addition to the combustion chamber 1 which is a source of heat and a primary heat transfer field, a convection chamber 2 which is a secondary heat transfer field and a connection path 3 which is a heat transfer field. And a decompression steam chamber 4. By arranging the combustion chamber 1 on the upper side and the convection chamber 2 on the lower side to circulate the combustion exhaust gas from the upper side to the lower side, an upper high temperature condition and a lower low temperature condition are formed, and the heat medium is circulated from the lower side to the upper side. By performing countercurrent heat exchange in each stage, the combustion heat of the combustion exhaust gas can be recovered very efficiently and the heat medium vaporized from above can be taken out.

  The combustion heat generated in the combustion chamber 1 is transferred to the heat medium inside the upper water tube group 1b (or the outer peripheral portion of the water cooling wall of the combustion chamber 1). The heat medium that has absorbed heat is normally heated to 80 to 90 ° C., maintained in a vaporized state, and transferred to the vacuum steam chamber 4. Further, the combustion exhaust gas generated by the combustion reaction is reduced in temperature (about 150 to 200 ° C.) and transferred to the convection chamber 2 via the exhaust part 1 c and the connection part 3.

  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, 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 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 via the connection path 3 is absorbed by the heat medium flowing in the lower water tube group 2b while the combustion exhaust gas flows through the exhaust gas flow passage 2a. Here, for the lower water pipe group 2b or the like, it is preferable to use a hollow rod having fins arranged 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 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.

[Heat exchange unit]
In the heat exchange unit 20, the second heat exchange unit 6 is disposed in the upper heat exchange space 8 where the gas phase heat medium exists, and in the liquid layer of the lower heat exchange space 9 where the liquid phase heat medium exists. A first heat exchange unit 7 is provided. In the second heat exchanging unit 6 disposed above, the heat exchange (latent heat) of the gas phase heat medium having a high temperature (about 80 to 90 ° C.) and the feed water flowing through the second heat exchanging unit 6 is performed. Endothermic). 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.

  A part of the supply water supplied to the introduction flow path Wa is circulated to the bypass flow path B and is also circulated to the first heat exchange unit 7. The supply water that has circulated through the first heat exchange section 7 is merged with the supply water that has circulated through the bypass flow path, and is circulated to the second heat exchange section 6 via the connection flow path Wb, as heated water from the supply flow path Wc. Be served. The bypass flow rate uses the output of the temperature sensor S provided in the lower communication flow path Lb as an index, and the hot water flow path W or the bypass flow so that the temperature of the heat medium returned to the main unit 10 falls within a predetermined range. It is controlled by the control unit 5 that brakes the control valve V provided in the path B. When the supply water supplied to the 1st heat exchange part 7 is low temperature, generation | occurrence | production of the low temperature corrosion etc. accompanying generation | occurrence | production of a large amount of condensed water by cooling of the combustion exhaust gas in the main body unit 10 can be prevented. It is possible to adjust the fluctuation factors such as the temperature condition of the supply water and the temperature condition of the warming water with respect to the main body unit 10 to ensure stable heat exchange efficiency and to prevent the occurrence of low temperature corrosion or the like.

  As long as the main unit 10 is operated, a gas phase heat medium is always supplied to the upper heat exchange space 8, and thus the second heat exchange unit 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. 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.

  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 lower heat exchange space 9 is disposed in the liquid phase heat medium (in the liquid layer). 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.

  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. ) Heat exchange under low temperature conditions (sensible heat absorption), the absorbed water is heated 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 and the lower flow path Tb. 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 a difference in water level from the liquid level of the liquid phase heat medium in the main unit 10. Therefore, a stable heat medium circulation system can be formed. Further, since the liquid phase heat medium existing in the lower heat exchange space 9 has a large heat capacity (especially when water or the like is used), a rapid temperature change occurs with respect to the temperature change (lower temperature) of the supplied water. The heat medium having a stable temperature can be returned to the main unit 10. Therefore, even when the temperature of the supply water is suddenly lowered, it is possible to control the bypass flow rate without causing a sudden change such as the occurrence of overshoot or undershoot.

[Hot heat transfer function with fluid transfer in this water heater]
In the hot water heater, warm heat is transferred between three fluids of combustion exhaust gas, heat medium, and supply water as follows.
(1) In the combustion chamber 1, the combustion exhaust gas is reduced in temperature (about 150 to 200 ° C.) by exchanging heat in the upper water tube group 1b from a high temperature state immediately after generation (about 700 to 800 ° C.). 1 c is introduced into the convection chamber 2 via the connection path 3. In the convection chamber 2, the temperature is reduced by exchanging heat in the lower water tube group 2 b and the like, and is discharged from the lower exhaust part 2 c through the exhaust gas flow passage 2 a.
(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. 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 80 to 90 ° 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 exchange unit 7 and then circulated and heated to the second heat exchange unit 6 (about 70 to 80 ° C.). Supplied as warm water. Further, the bypass flow rate of the feed water is controlled as in the second configuration example.

DESCRIPTION OF SYMBOLS 10 Main body unit 20 Heat exchange unit 1 Combustion chamber 1a Combustion burner 1b Water pipe group 1c Exhaust part 1d Flame 2 Convection chamber 2a Exhaust gas flow path 2b Lower water pipe group etc. 2c Lower exhaust part 3 Connection path 4 Decompression steam chamber 5 Control part 6 2nd Heat exchange unit 7 First heat exchange unit 7a, 7b Heat exchange unit 8 Upper heat exchange space 9 Lower heat exchange space B Bypass channel Ba Branch channel E Third heat exchange unit S Temperature sensor Lu Upper communication channel Lb Lower communication Flow path P Circulation pump S Temperature sensor Tu Upper flow path Tb Lower flow path V Control valve V1, V2, V3 valve (open / close valve or control valve)
W Hot water flow path Wa Introduction flow path Wb Connection flow path Wc Delivery flow path Wd Supply flow path

Claims (6)

A combustion chamber provided with a combustion burner and a water tube group through which a heat medium flows, an upper flow passage disposed above the combustion chamber and connected to the water tube group, and disposed below the combustion chamber. A lower flow passage connected to the water pipe group, and a main body unit,
An upper heat exchange space that communicates with the upper flow passage through the upper communication flow path and through which the high-temperature heat medium flows down, and a lower heat exchange space that communicates through the lower flow passage and the lower communication flow path and through which the low-temperature heat medium flows. And a second heat exchange part is disposed in the upper heat exchange space, a first heat exchange part is disposed in the lower heat exchange space,
Supply water supplied to the introduction flow path to the first heat exchange section is circulated from the first heat exchange section to the second heat exchange section through a connection flow path, and the second heat exchange section is supplied. A heat exchange unit comprising: a warm water channel provided as warm water from the channel; and a bypass channel branched from the introduction channel and connected to the connection channel;
The water heater characterized by having. Combustion exhaust gas generated in the combustion chamber is heat-exchanged with the heat medium in the water tube group, is reduced in temperature and discharged from the exhaust part,
The heat medium filling the inside of the water tube group absorbs combustion heat by heat exchange with the combustion exhaust gas, is heated and transferred to the upper heat exchange space via the upper flow passage, and the second heat exchange The temperature is reduced by exchanging heat in the section and flows down to the lower heat exchange space, the temperature is decreased by exchanging heat in the first heat exchange section, and circulates in the water pipe group through the lower flow path. A circulating flow is formed,
Supply water is circulated through the first heat exchange unit and the second heat exchange unit, heated and supplied as heated water, and an output of a temperature sensor provided in the lower communication channel is input, The water heater according to claim 1, wherein a flow rate of supply water to be circulated through the bypass flow path is adjusted by a controller that brakes a control valve provided in the hot water flow path or the bypass flow path.   The first heat exchanging part is constituted by a plurality of heat exchanging units arranged in series, and the connecting part of each heat exchanging unit is branched and connected to the bypass flow path, and is distributed to the first heat exchanging part. The water heater according to claim 1 or 2, wherein the flow rate of the feed water is adjusted. The main unit constitutes a pressureless water heater,
The liquid phase heat medium heated in the water tube group is transferred to the upper heat exchange space through the upper flow passage, and is heat-reduced and reduced in the second heat exchange section, so that the lower heat A circulation flow of an in-phase heat medium is formed that flows down to the exchange space, is reduced in temperature by exchanging heat in the first heat exchange section, and circulates in the water pipe group through the lower flow passage. The water heater according to any one of claims 1 to 3.   The lower communication channel includes a heat recovery unit, and performs heat exchange between combustion exhaust gas generated in a combustion chamber of the main unit and a heat medium flowing from the heat exchange unit to the lower communication channel. The water heater according to claim 4. The main unit constitutes a reduced pressure water heater,
A combustion chamber having an upper water pipe group having the combustion burner and an upper exhaust part, in which a heat medium flows;
A convection chamber disposed below the combustion chamber, having an exhaust gas flow path and a lower exhaust part, and having a lower water pipe group connected to the upper water pipe group and the lower flow path through which a heat medium flows. When,
A connection path connecting the upper exhaust part and the exhaust gas flow path;
A reduced pressure steam chamber disposed at an upper portion of the combustion chamber and connected to the upper water pipe group and the upper flow passage;
And the heat exchange unit comprises:
An upper heat exchange space that is communicated with the reduced-pressure steam chamber via the upper flow passage in the upper communication flow path and is filled with a gas phase heat medium;
A lower heat exchange space is formed which is communicated with the lower water pipe group via the lower flow passage in the lower communication flow path and filled with a liquid phase heat medium,
The water heater according to any one of claims 1 to 3, wherein the second heat exchange section is disposed in the upper heat exchange space, and the first heat exchange section is disposed in the lower heat exchange space.

Images