JP6355394B2 - Vacuum water heater - Google Patents

Description

  The present invention relates to a vacuum water heater, and more particularly to a vacuum water heater provided with two hot water hot water and hot water hot water circuits.

  Conventionally, as shown in FIG. 4, a burner 50, a combustion chamber 51, a decompression steam chamber 52, a heat transfer water H, a heat exchanger 53, a water pipe 54, an extraction pump (not shown) and the like are provided, and the inside of the can body 55 is extracted. By reducing the pressure by the pump to a state close to vacuum, the heat transfer water H is boiled at a temperature of 100 ° C. or less, and the steam condenses on the surface of the heat exchanger 53 to supply water in the heat exchanger 53. A vacuum water heater that heats and produces hot water is known (for example, Patent Document 1). This type of vacuum hot water machine has the advantage of being able to quickly supply hot water at the required temperature to the load side.

JP-A-11-337002

  However, in the conventional vacuum hot water machine, the heat held in the exhaust gas is heat-exchanged in two stages to the hot water via the heating medium, and generally the heating medium temperature is controlled at 80 to 90 ° C. There was a limit to reducing the exhaust gas temperature at the can outlet and improving the thermal efficiency.

  Therefore, the present invention provides a vacuum water heater that can reduce exhaust gas temperature and improve thermal efficiency in a two-circuit vacuum water heater with hot water as well as hot water hot water.

In order to achieve the above object, a vacuum water heater according to the present invention includes a first vacuum water heater provided with a heat medium heating burner, a first hot water heat exchanger, and a first heating heat exchanger; A second hot water heater provided with a second hot water supply heat exchanger and a second heating heat exchanger and configured to heat the heat medium with the exhaust gas of the first vacuum hot water machine, The first hot water supply heat exchanger is connected in series to the second hot water supply heat exchanger so that water is supplied from the second hot water supply heat exchanger, and the first heating heat exchanger is connected to the second heat supply heat exchanger. A second hot water supply bypass pipe that is connected in series to the second heating heat exchanger and bypasses the second hot water supply heat exchanger so that water is supplied from the heating heat exchanger, and the second hot water supply A second hot water supply flow rate control valve for controlling a bypass flow rate flowing through the bypass pipe, and for the second heating A heating bypass pipe that bypasses the exchanger, a heating flow control valve that controls a bypass flow rate that flows through the heating bypass pipe, and a heat medium temperature of the second vacuum water heater is that of the first vacuum water heater. A control system for controlling the second hot water supply flow rate control valve so as to have a third set temperature lower than the heat transfer medium temperature, and the hot water supply hot water load is reduced or cut off, so that the heat transfer medium temperature of the second vacuum hot water heater is When the second set temperature higher than the third set temperature is reached, the flow rate to the heating bypass pipe is decreased or stopped by the heating flow control valve to increase the water supply to the second heating heat exchanger. When the heat medium temperature of the control system and the second vacuum water heater rises from the second set temperature and reaches the first set temperature, the heat medium temperature of the second vacuum water heater is based on the heat medium temperature of the second vacuum water heater. Before the heating medium temperature does not exceed the first set temperature A second burner control output for controlling the fuel flow rate of the burner is a first output for controlling the fuel flow rate of the burner so that the heat medium temperature of the first vacuum hot water machine becomes the first set temperature. And a control system for controlling the fuel flow rate of the burner by a smaller control output as compared with the control output for the burner .

  It is preferable to further include a first hot water supply bypass pipe that bypasses the first hot water supply heat exchanger, and a first hot water flow control valve that controls the flow rate of the first hot water bypass pipe.

When the hot water supply temperature of hot water at the outlet of the heat exchanger for the first hot water supply by a reduction in the supplying hot water load reaches elevated hot water limit set temperature of the first hot-water bypass pipe by the first hot-water flow control valve It is preferable to include a control system that adjusts the hot water supply hot water temperature to the hot water supply upper limit set temperature by controlling the flow rate.

  According to the present invention, in a vacuum hot water machine having two circuits of hot water supply and heating, the exhaust gas temperature from the can can be reduced and high thermal efficiency can be realized.

It is a schematic structure figure showing a 1st embodiment of a vacuum type hot water machine concerning the present invention. It is a diagram which shows the relationship between the temperature of a heat medium (water), and a vacuum degree. It is a schematic block diagram which shows 2nd Embodiment of the vacuum type hot water machine which concerns on this invention. It is a schematic block diagram which shows the conventional vacuum hot water machine.

  An embodiment of a vacuum hot water machine according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar component through all drawings and all embodiment.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of a vacuum water heater according to the present invention. As shown in FIG. 1, a vacuum hot water machine 1 includes a first vacuum hot water machine 5 including a heat medium heating burner 2, a first hot water supply heat exchanger 3, and a first heating heat exchanger 4; A second vacuum water heater 8 provided with a second hot water supply heat exchanger 6 and a second heating heat exchanger 7 and configured to heat the heat medium by the combustion exhaust gas of the first vacuum water heater 5; It has.

  The first hot water supply heat exchanger 3 is connected in series to the second hot water supply heat exchanger 6 so that water is supplied from the second hot water supply heat exchanger 6. The first heating heat exchanger 4 is connected in series to the second heating heat exchanger 7 so that water is supplied from the second heating heat exchanger 7.

  The first vacuum hot water machine 5 has the same basic structure as a conventional vacuum hot water machine, and is a heating medium heating burner 2, a first hot water supply heat exchanger 3, and a first heating heat exchanger 4. In addition, the combustion chamber 10 submerged in the can 9, the water tube group 11 penetrating the combustion chamber 10 up and down, and the heat exchangers 3, 4 provided above the heat medium H <b> 1 sealed in the can 9. Are incorporated, a decompression steam chamber 12 in which is installed, a bleed pump (not shown) for decompressing the decompression steam chamber 12, and the like.

  Since the second vacuum hot water machine 8 is not provided with a burner, it does not have a combustion chamber in the can body 13 and the heat medium H2 enclosed in the can body 13 is discharged from the first vacuum hot water machine 5. It is configured to exchange heat with the generated combustion exhaust gas G.

  The can 13 of the second vacuum hot water machine 8 is provided with a water pipe group 14 like the water pipe group 11 of the combustion chamber 10 of the first vacuum hot water machine 5, and the water pipe group 14 is a flue 15 of the exhaust gas G. It is arranged in the inside. A decompression steam chamber 16 that is decompressed by an extraction pump (not shown) is formed above the heat medium H2 in the can 13 of the second vacuum hot water machine 8, and the second hot water supply heat exchanger 6 is provided in the decompression steam chamber 16. And the heat exchanger 7 for 2nd heating is integrated.

  In the first vacuum hot water machine 5, water (heat medium water) is sealed in the can 9 as a heat medium. Since the inside of the can 9 of the first vacuum hot water machine 5 is decompressed by the extraction pump, the heat transfer water boils and evaporates below 100 ° C., and the latent heat possessed by the decompressed steam is Heat is transferred to the hot water in the first hot water supply heat exchanger 3 and the first heating heat exchanger 4 incorporated in the reduced pressure steam chamber 12, and the reduced pressure steam condenses and drops again as water after the heat transfer. It becomes heat transfer water.

  The heat medium of the first vacuum water heater 5 is controlled at a temperature of 100 ° C. or less, usually 80 ° C. to 90 ° C., and in this temperature range, the heat medium water undergoes a cycle of boiling, evaporation, heat transfer, and condensation. repeat. The heat medium temperature of the first vacuum hot water machine 5 can be controlled by adjusting the output of the burner 2.

The second vacuum hot water machine 5 also uses water as the heat medium H2. The heat medium H <b> 2 of the second vacuum hot water machine 8 is controlled at a temperature lower than the heat medium temperature of the first vacuum hot water machine 5. By keeping the heat medium temperature of the second vacuum type hot water machine 8 lower than the heat medium temperature of the first vacuum type hot water machine 5, the temperature of the exhaust gas coming out of the can 13 can be reduced even in the case of a vacuum type hot water machine. In general, in a vacuum water heater, the non-condensable gas generated in the can must be extracted with a bleed pump to maintain the vacuum so that it does not exceed atmospheric pressure. I must. In particular, hydrogen gas, which is a non-condensable gas, extremely inhibits heat transfer even in a very small amount, and thus needs to be extracted.

  When the heat medium temperature of the second vacuum hot water machine 8 is lower than the heat medium temperature of the first vacuum water heater 5, when the temperature of the heat medium H2 is extremely lowered and the degree of vacuum in the can 11 is increased, There is a possibility that the air cannot be extracted beyond the specification capacity of the air extraction pump. Therefore, the heat medium temperature of the second vacuum hot water machine 8 is maintained at a degree of vacuum that allows the extraction pump (not shown) to discharge the non-condensable gas in the can 13 of the second vacuum hot water machine 8. In consideration of the degree of vacuum, it is desirable to set in the range of 60 ° C to 70 ° C. FIG. 2 shows the relationship between the temperature of the heat transfer water and the degree of vacuum. In addition, the temperature of the heat medium of the second vacuum hot water machine 8 is controlled to be higher than the temperature at which the exhaust gas G exchanging heat with the heat medium H2 is condensed, so that low-temperature corrosion and white smoke generation of the can 13 and the flue 15 are prevented. Can be prevented.

  The heat exchange capacity of the second hot water supply heat exchanger 6 is such that the heat medium H2 of the second vacuum hot water machine 8 can be easily lowered to the set temperature so that the first vacuum hot water machine 5 and the second vacuum hot water are used. It is preferable to select one having a heat exchange capacity larger than the exchange heat quantity of the second vacuum hot water machine 8 calculated from the ratio of the heat exchange quantity of the machine 8.

  The heat exchange capacity of the second heating heat exchanger 7 is a control output based on the heat medium temperature of the first vacuum hot water heater 5 when the water supply load is only the heating load and the fuel flow rate control is performed at a set temperature T1 described later. The control output MV2 according to the heat medium temperature of the MV1 and the second vacuum water heater 8 is substantially the same, so that the control of the fuel flow rate does not become unstable, the first vacuum water heater 5 and the second vacuum water heater It is preferable to select the second vacuum water heater 8 calculated from the ratio of the heat exchange amount of 8 that has a heat exchange capability equivalent to the exchange heat amount.

  Since the second vacuum water heater 8 does not include a burner, the temperature of the heat medium H2 is controlled by controlling the flow rate of the water supply W to the second hot water supply heat exchanger 6 and the second heating heat exchanger 7. Can be controlled.

  In order to control the flow rate of the feed water W to the second hot water supply heat exchanger 6 and the second heating heat exchanger 7, a second hot water supply bypass pipe 17 that bypasses the second hot water supply heat exchanger 6; The second hot water flow control valve 18 for controlling the bypass flow through the hot water bypass pipe 17, the heating bypass pipe 19 that bypasses the second heating heat exchanger 7, and the bypass flow through the heating bypass pipe 19 A heating flow control valve 20 to be controlled is provided.

  In the illustrated example, the second hot water flow rate control valve 18 is a proportional three-way valve that can adjust the flow rate of the hot water inlet side pipe 6a at the same time as adjusting the bypass flow rate. In the illustrated example, the heating flow control valve 20 is a switching valve (ON-OFF valve) that can switch between the heating bypass pipe 19 and the hot water inlet side pipe 7a on the heat exchange side. In addition, as long as the water supply amount of the second hot water supply heat exchanger 6 and the second heating heat exchanger 7 can be adjusted by adjusting the bypass flow rate of the bypass pipes 17 and 19, the connection position, the type of valve, The number is not limited.

  The first heating heat exchanger 4 may have a heat exchange capacity equivalent to that of the first hot water supply heat exchanger 3. The second heating heat exchanger 7 may have a heat exchange capacity equivalent to that of the second hot water supply heat exchanger 6.

  The vacuum water heater 1 having the above configuration can reduce the exhaust gas temperature and obtain high thermal efficiency even if it is two circuits of the heating circuit of the hot water supply circuit.

  Further, when either one of the first vacuum hot water machine 5 and the second vacuum hot water machine 8 is damaged, it can be repaired by replacing only the damaged one, so that the repair cost can be reduced.

  Moreover, it is possible to change the main material of the 2nd vacuum hot water machine 8 according to a condition, and the exit waste gas temperature of the 1st vacuum hot water machine 5 can be determined with the heat-resistant temperature of the material. For example, if a can body using an aluminum material with good heat absorption can be downsized, and if corrosive condensed water is generated, a can body using stainless steel can extend the life. .

  In addition, when the vacuum hot water machine 1 is started, the supply of hot water to the second hot water supply heat exchanger 6 is shut off by the second hot water flow control valve 18, and the first hot water supply heat is supplied from the hot water bypass pipe 17. By flowing all the hot water supply hot water to the exchanger 3, it is possible to suppress the quick start-up and the generation of condensed water of the exhaust gas G when the second vacuum hot water machine 8 is started.

  Next, the control of the vacuum water heater 1 having the above configuration will be described with reference to FIG. In FIG. 1, a dotted line indicates a control system.

  In the illustrated example, the temperature of the heating medium of the first vacuum hot water machine 5 and the second vacuum hot water machine 8 is controlled by the control device 21.

  In the first vacuum water heater 5, the temperature of the heat medium H1 is detected by a temperature detector TT1 such as a thermistor sensor, and the calculator 22 calculates the detected temperature of the temperature detector TT1 to be the first set temperature T1. By sending a control output MV1 for controlling the fuel flow rate to the fuel flow rate adjusting mechanism 23 and adjusting the flow rate of the fuel F supplied to the burner 2, the heating medium H1 of the first vacuum hot water machine 5 reaches the first set temperature T1. Adjusted.

  In the normal state, the switching valve constituting the second heating flow control valve 20 is switched to the bypass side, and does not supply water to the second heating heat exchanger 7, and the first heating heat exchanger 4. A switching valve having a structure for supplying water only to the tank is used. The second heating flow rate control valve is not limited to the on / off switching valve, but may be any one that can also control the feed water flow rate to the second heating heat exchanger 7 by controlling the feed water flow rate to the heating bypass pipe 19. A proportionally operated three-way valve whose bypass side is normally open, and other control valves can also be used.

  In the second vacuum hot water machine 8, the temperature of the heat medium H2 is detected by the temperature detector TT2 such as a thermistor sensor, and the bypass flow rate calculated by the calculator 24 so that the detected temperature becomes the third set temperature T3. The control output MV3 for control is sent to the second hot water supply flow rate control valve 18, and the flow rate of the water supply to the second hot water supply heat exchanger 6 is adjusted by adjusting the bypass flow rate flowing through the second hot water supply bypass pipe 17. Thus, the temperature of the heat medium H2 of the second vacuum hot water machine 8 is adjusted to the third set temperature T3.

  Since the second heating flow control valve 20 is open to the bypass side in the normal state, the water is not supplied to the second heating heat exchanger 7 of the second vacuum hot water heater 8 in the normal operation state, and the second The temperature of the heat medium of the vacuum hot water machine 8 is controlled exclusively by the second hot water supply flow control valve 18.

  Even if heating hot water and hot water supply hot water are simultaneously loaded, the first vacuum water heater 5 can mainly perform heat exchange with heating hot water, and the second vacuum water heater 8 can perform heat exchange with hot water supply hot water. The heat medium temperature of the second vacuum hot water machine 8 can be maintained at the third set temperature T3, and the exhaust gas temperature can be reduced.

  When the hot water supply hot water is shut off with the heating hot water load, the second vacuum water heater 8 cannot maintain the third set temperature T3, and the temperature of the heat medium H2 starts to rise. Is set to a second set temperature T2 (T1> T2> T3), the detected temperature of the heat medium H2 is compared by the comparator 25, and the temperature of the heat medium H2 is equal to or higher than the second set temperature T2. In response to a command from the comparator 25, the switching valve constituting the second heating flow control valve 20 is switched to the second heating heat exchanger 7 side to supply water to the second heating heat exchanger 7. Reduce the temperature of H2.

  Even when the switching valve constituting the second heating flow control valve 20 is switched to the second heating heat exchanger 7 side, it is assumed that the temperature of the heat medium H2 further rises from the second set temperature T2. Therefore, in the control device 21, when the temperature of the heat medium H2 of the second vacuum hot water machine 8 reaches the first set temperature T1, the heat medium detected by the temperature detector TT2 of the second vacuum hot water machine 8 Based on the temperature, a second burner control output MV2 for controlling the fuel flow rate of the burner 2 calculated by the calculator 26 so that the temperature of the heating medium H2 does not exceed the first set temperature T1 is output to the comparator 27. Then, a first flow rate control for controlling the fuel flow rate of the burner 2 calculated by the calculator 22 so that the temperature of the heat medium detected by the temperature detector TT1 of the first vacuum water heater 5 becomes the first set temperature T1. The burner control output MV1 is output to the comparator 27, the second burner control signal MV2 and the first burner control output MV1 are compared, and the smaller control output (MV1 or MV2) is the fuel flow rate adjustment mechanism. 23. And controlling fuel flow toner 2, to adjust the heating power of the burner 2.

As described above, when the load of hot water (water supply) is both the heating hot water and the hot water supply hot water, the heating hot water exchanges heat with the first vacuum hot water heater 5, and the hot water supply hot water is mainly the second vacuum hot water heater 8. If the load of hot water is only heating hot water, heat exchange is performed by both the first vacuum hot water machine 5 and the second vacuum hot water machine 8 so that the retained heat of the exhaust gas is effectively converted into hot water. Heat exchange can be performed.
In addition, even if the hot water supply load is suddenly reduced or cut off, the rapid temperature increase of the heat medium temperature of the second vacuum hot water machine 8 can be alleviated, and a safer and more prompt response can be made to the hot water supply load.

  Next, a second embodiment of the vacuum hot water machine according to the present invention will be described with reference to FIG. In addition, the same code | symbol was attached | subjected about the same or similar component similar to the said 1st Embodiment.

  In the second embodiment, the hot water inlet side pipe 3a and the hot water outlet side pipe 3b of the first hot water supply heat exchanger 3 of the vacuum hot water machine of the first embodiment are connected, and the first hot water supply heat exchanger 3 is connected. The first hot water supply bypass pipe 28 that bypasses the first hot water supply bypass pipe 28 and the outlet temperature of the first hot water supply heat exchanger 3 are detected. The temperature detector 30 and the temperature detection signal of the temperature detector 30 are received, and the control output MV4 calculated by the calculator 31 so as not to exceed the hot water supply upper limit set temperature T4 is transmitted to the first hot water flow control valve 29. It is configured as follows. Other configurations are the same as those in the first embodiment. As the first hot water supply flow control valve 29 in the illustrated example, a proportional control three-way valve is used, but other types of control valves may be used.

  When the load of hot water is both heating hot water and hot water supply hot water, when the load of hot water supply hot water is extremely small, the hot water supply hot water temperature at the outlet of the first hot water supply heat exchanger 3 may rise more than necessary. In such a case, according to the above-described configuration of the second embodiment, when the outlet hot water temperature of the first hot water supply heat exchanger 3 reaches the hot water supply upper limit temperature T4, the proportionality constituting the first hot water supply flow control valve 29 is configured. The bypass flow rate flowing through the first hot water supply bypass pipe 28 is controlled by a control type three-way valve, and the hot water temperature at the outlet of the first hot water supply heat exchanger 3 is controlled so as not to exceed the hot water supply upper limit set temperature T4. The temperature T4 is maintained, and the hot water supply temperature is prevented from rising above the hot water supply upper limit set temperature.

  By performing the control of the second embodiment, the first vacuum hot water machine 5 shares the role of heat exchange with the heating hot water, and the second vacuum hot water machine 8 mainly shares the role of heat exchange with the hot water supply hot water. By further clarifying and reducing wasteful heat exchange with the hot water supply hot water in the first vacuum hot water heater 5, further higher efficiency can be achieved.

DESCRIPTION OF SYMBOLS 1 Vacuum hot water machine 2 Burner 3 1st hot water supply heat exchanger 4 1st heating heat exchanger 5 1st vacuum hot water machine 6 2nd hot water supply heat exchanger 7 2nd heating heat exchanger 8 2nd vacuum Type hot water heater 17 Second hot water supply bypass pipe 18 Second hot water supply flow control valve 19 Heating bypass pipe 20 Heating flow control valve 21 Controller 23 Fuel flow rate adjusting mechanism 28 First hot water supply bypass pipe 29 First hot water supply flow rate Control valve

Claims (3)

A first vacuum water heater comprising a heat medium heating burner, a first hot water supply heat exchanger, and a first heating heat exchanger;
A second hot water heater provided with a second hot water supply heat exchanger and a second heating heat exchanger, and configured to heat the heat medium with the exhaust gas of the first vacuum hot water machine,
The first hot water supply heat exchanger is connected in series to the second hot water supply heat exchanger so that water is supplied from the second hot water supply heat exchanger,
The first heating heat exchanger is connected in series to the second heating heat exchanger so that water is supplied from the second heating heat exchanger ,
A second hot water supply bypass pipe for bypassing the second hot water supply heat exchanger;
A second hot water supply flow rate control valve for controlling a bypass flow rate flowing through the second hot water supply bypass pipe;
A heating bypass pipe that bypasses the second heating heat exchanger;
A heating flow control valve for controlling a bypass flow rate flowing through the heating bypass pipe;
A control system for controlling the second hot water supply flow rate control valve so that the heat medium temperature of the second vacuum water heater becomes a third set temperature lower than the heat medium temperature of the first vacuum water heater;
When the hot water load for hot water supply is reduced or shuts down and the heat medium temperature of the second vacuum hot water machine reaches a second set temperature higher than the third set temperature, the heating flow control valve causes the heating bypass pipe to enter the heating bypass pipe. A control system that decreases or stops the flow rate of the second heating unit to increase the amount of water supplied to the second heating heat exchanger;
When the heat medium temperature of the second vacuum water heater rises above the second set temperature and reaches the first set temperature, the heat medium temperature is set based on the heat medium temperature of the second vacuum water heater. The second burner control output for controlling the fuel flow rate of the burner so as not to exceed the first set temperature is set such that the heat medium temperature of the first vacuum hot water machine becomes the first set temperature. A control system for controlling the fuel flow rate of the burner by the smaller control output compared to the control output for the first burner for controlling the fuel flow rate of the burner;
Vacuum hot press, characterized in that it comprises a. Claim 1, wherein the first hot water bypass pipe that bypasses the heat exchanger for the first hot water supply, further comprising a first hot-water flow control valve for controlling the flow rate of the first hot water supply bypass pipe A vacuum water heater as described in 1. When the hot water supply temperature of hot water at the outlet of the heat exchanger for the first hot water supply by a reduction in the supplying hot water load reaches elevated hot water limit set temperature of the first hot water bypass pipe by the first hot-water flow control valve The vacuum hot water machine according to claim 2 , further comprising a control system for adjusting a hot water supply hot water temperature to the hot water supply upper limit set temperature by controlling a flow rate.

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