JP6355377B2 - Vacuum water heater - Google Patents

Vacuum water heater Download PDF

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JP6355377B2
JP6355377B2 JP2014059913A JP2014059913A JP6355377B2 JP 6355377 B2 JP6355377 B2 JP 6355377B2 JP 2014059913 A JP2014059913 A JP 2014059913A JP 2014059913 A JP2014059913 A JP 2014059913A JP 6355377 B2 JP6355377 B2 JP 6355377B2
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vacuum
hot water
heat
flow rate
heat medium
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JP2015183914A (en
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訓央 林
訓央 林
孝幸 正野
孝幸 正野
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株式会社日本サーモエナー
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Description

  The present invention relates to a vacuum hot water machine.

  Conventionally, as shown in FIG. 5, a burner 30, a combustion chamber 31, a decompression steam chamber 32, a heat transfer water H, a heat exchanger 33, a water pipe 34, an extraction pump (not shown) and the like are provided, and the inside of the can 35 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 33 to supply water in the heat exchanger 33. 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, conventional vacuum water heaters exchange heat of exhaust gas into warm water through a heating medium in two stages, and generally control the heating medium temperature at 80 to 90 ° C. There was a limit to reducing exhaust gas temperature at the body outlet and improving thermal efficiency.

  Then, this invention sets it as the main objective to provide the vacuum type water heater which can improve thermal efficiency, without increasing a heat-transfer area significantly.

In order to achieve the above object, a vacuum water heater according to the present invention includes a first vacuum water heater including a heat medium heating burner and a first heat exchanger, a second heat exchanger, and the first heat exchanger. Flow rate control for controlling the second vacuum water heater configured to heat the heat medium with the exhaust gas of the vacuum water heater, a bypass pipe that bypasses the second heat exchanger, and a bypass flow rate that flows through the bypass pipe And a control device for controlling the heat medium of the second vacuum hot water machine to a heat medium set temperature lower than the heat medium set temperature of the first vacuum hot water machine by controlling the flow rate control valve. The first heat exchanger is connected to the second heat exchanger so that water is supplied from the second heat exchanger.

  The second vacuum hot water machine is preferably sealed with a heat medium having a standard boiling point of less than 100 ° C.

  The control device includes: a first control output for controlling a fuel flow rate to the burner so that a heat medium of the first vacuum hot water machine becomes a predetermined heat medium set temperature; and a second control of the second vacuum hot water machine. Fuel flow rate to the burner so that the heating medium becomes a predetermined heating medium temperature setting value lower than the heating medium setting temperature of the first vacuum hot water machine and higher than the heating medium setting temperature for controlling the flow rate control valve It is preferable that the fuel flow rate of the burner is controlled by the control output having the smaller fuel flow rate of the first control output and the second control output.

  According to the present invention, it is possible to improve the thermal efficiency without significantly increasing the heat transfer area.

It is a schematic structure figure showing a 1st embodiment of a vacuum type hot water machine concerning the present invention. It is a schematic block diagram which shows the vacuum type hot water machine of FIG. 1 with a control system. 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 diagram which shows the relationship between the temperature of a heat medium (water), and a vacuum degree. It is a vertical side view 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, the vacuum water heater 1 includes a first vacuum water heater 4 including a heat medium heating burner 2 and a first heat exchanger 3, a second heat exchanger 5, and a first vacuum. A second vacuum hot water machine 6 configured to heat the heat medium with the exhaust gas G discharged from the hot water machine 4, and the first heat exchanger 3 supplies water from the second heat exchanger 5. The second heat exchanger 5 is connected in series so as to be supplied. The 1st vacuum type hot water machine 4 and the 2nd vacuum type hot water machine 6 can be arranged in series like the example of illustration.

  The first vacuum hot water machine 4 has the same basic structure as a conventional vacuum hot water machine, and is submerged in a can 7 in addition to the heat medium heating burner 2 and the first heat exchanger 3. Combustion chamber 8, water tube group 9 vertically passing through the combustion chamber 8, reduced pressure steam chamber 10 provided in the upper part of the heat medium H <b> 1 sealed in the can body 7 and incorporating the first heat exchanger 3, reduced pressure steam chamber A bleed pump (not shown) or the like that depressurizes 10 is provided.

  Since the second vacuum hot water machine 6 is not provided with a burner, it does not have a combustion chamber in the can body 11, and the heat medium H2 enclosed in the can body 11 is discharged from the first vacuum hot water machine 4. It is configured to exchange heat with the generated combustion exhaust gas G. The can body 11 includes a water tube group 12 as in the case of the water tube group 9 of the combustion chamber 8 of the first vacuum hot water machine 4, and the water tube group 12 is disposed in the flue 13 of the exhaust gas G. A decompression steam chamber 11a is formed above the heat medium H2 in the can body 11, and the second heat exchanger 5 is incorporated in the decompression steam chamber 11a. In addition, about the water pipe group 12 of the 2nd vacuum-type hot water machine 6, although the term "water pipe" is used for convenience of explanation, a heat medium other than water may enter as described later.

  In the first vacuum hot water machine 4, water (heat medium water) is enclosed as a heat medium in the can body 7. Since the inside of the can 7 of the first vacuum hot water machine 4 is decompressed by the extraction pump, the heat transfer water boils and evaporates at less than 100 ° C., and the latent heat possessed by this decompressed steam is Heat is transferred to the hot water in the first heat exchanger 3 incorporated in the upper reduced-pressure steam chamber 10, and the reduced-pressure steam is condensed after being transferred to water and dripped to become heat transfer water. The heat medium of the first vacuum hot water machine 4 is controlled at a heat medium set temperature of 100 ° C. or less, usually 80 ° C. to 90 ° C., and in this set temperature range, the heat medium water is boiled, evaporated, heat transferred, Repeat the condensation cycle. The heat medium temperature of the first vacuum hot water machine 4 can be controlled by adjusting the output of the burner 2.

  The heat medium H <b> 2 of the second vacuum hot water machine 6 can be controlled at a lower heat medium set temperature than the heat medium H <b> 1 of the first vacuum hot water machine 4. Since the second vacuum hot water machine 6 does not include a burner, the temperature of the heat medium H2 can be controlled by controlling the flow rate of the feed water W to the second heat exchanger 5.

In order to control the feedwater flow to the second heat exchanger 5, as shown in FIG. 1, the second heat by connecting a hot water outlet pipe 5 b and hot water inlet pipe 5 a of the second heat exchanger 5 A bypass pipe 14 for bypassing the exchanger 5 is provided, and a flow rate control valve 15 for adjusting a bypass flow rate flowing through the bypass pipe 14 is provided. The flow control valve 15 can adjust the flow rate of the hot water inlet side piping 5a as a three-way valve for proportional operation and simultaneously adjust the flow rate of the hot water inlet side pipe 5a. The type and number of valves are not limited.

  As described above, the second vacuum hot water machine 6 is set to a vacuum type by setting the heat medium set temperature lower than the heat medium set temperature of the first vacuum hot water machine 4 and keeping the temperature of the heat medium H2 low. Even with a hot water machine, the exhaust gas temperature can be reduced as compared with the conventional one.

  In the conventional vacuum hot water machine, since the difference between the exhaust gas temperature and the heat medium temperature is small, a portion where the heat transfer surface does not sufficiently function as the heat transfer surface may occur. Since the heating medium temperature of the water heater 6 can be reduced compared to the conventional one, the difference between the exhaust gas temperature and the heating medium temperature can be increased compared to the conventional one, and as a result, the exhaust gas temperature is reduced compared to the conventional one. Although possible, even if the heat transfer area of the first vacuum water heater 4 and the heat transfer area of the second vacuum water heater 6 are summed, the heat transfer area is the same as that of the conventional vacuum water heater. It can be an area.

  In general, in a vacuum hot water machine, a non-condensable gas generated in a can must be extracted with a bleed pump to maintain a vacuum so as not to exceed atmospheric pressure. 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. The timing of operating the extraction pump to extract the non-condensable gas can be extracted periodically by a timer, or the difference between the hot water temperature of the reduced pressure steam temperature and the heat exchanger outlet temperature exceeds a predetermined value. Can be extracted irregularly.

  In the second vacuum water heater 6, since the heat medium set temperature is set low, when the temperature of the heat medium H2 is extremely lowered and the degree of vacuum in the can 11 is increased, the extraction capacity exceeds the specification capacity of the extraction pump. When water is used as the heating medium H2, it is desirable to set the heating medium temperature in the range of 60 ° C to 70 ° C in consideration of the degree of vacuum. FIG. 4 shows the relationship between the heat medium temperature and the degree of vacuum when the heat medium is water. The temperature of the heat medium H2 of the second vacuum hot water machine 6 is set to be equal to or higher than the temperature at which the exhaust gas G that exchanges heat with the heat medium H2 is condensed, thereby preventing low temperature corrosion and white smoke generation of the can 11. be able to.

  By using a heating medium having a boiling point at 1 atm, that is, a standard boiling point of less than 100 ° C., instead of water as the heating medium of the second vacuum hot water machine 6, it is possible to further increase the efficiency. However, in this case, it is preferable to set the standard boiling point of the heating medium as a lower limit of about 60 ° C. so that the inside of the second vacuum hot water machine 6 does not become atmospheric pressure or more due to boiling of the heating medium due to the outside air temperature. For example, when a heat medium having a standard boiling point of 70 ° C. is adopted as the heat medium H2 of the second vacuum hot water machine 6, the degree of vacuum is increased too much depending on the physical properties of the heat medium and the presence or absence of non-condensable gas. Therefore, the heat medium temperature can be controlled at about 50 ° C., and the exhaust gas temperature can be reduced as compared with the case where water is used as the heat medium.

  FIG. 2 is a schematic configuration diagram showing an example of a control system of the vacuum hot water machine 1 shown in FIG. The first vacuum water heater 4 detects the temperature of the heat medium H1 with a temperature detector TT1 such as a thermistor sensor, and the arithmetic unit 21 so that the detected temperature becomes the heat medium set temperature T1 set in the control device 20. The control output MV1 for fuel flow rate control calculated in step S1 is sent to the fuel flow rate adjustment mechanism 22, and the flow rate of the fuel F supplied to the burner 2 is adjusted, so that the heating medium of the first vacuum hot water machine 4 is set to the set temperature T1. Adjust the temperature.

  The second vacuum water heater 6 detects the temperature of the heat medium by a temperature detector TT2 such as a thermistor sensor, and the arithmetic unit 23 adjusts the detected temperature to the heat medium set temperature T3 set in the control device 20. By sending the calculated control output MV3 for bypass flow rate control to the flow rate control valve 15 and adjusting the bypass flow rate flowing through the bypass pipe 14, the temperature of the heat medium H2 of the second vacuum water heater 6 is changed to the heat medium set temperature T3. Adjust.

As described above, the heat medium set temperature T3 of the second vacuum type hot water machine 6 is lower than the heat medium set temperature T1 of the first vacuum type hot water machine 4, and the extraction pump (not shown) uses the second vacuum. It is set so that the non-condensable gas in the can 11 of the water heater 6 can be kept at a vacuum level that can be discharged.
When the measured value of the heat medium temperature by the temperature detector TT2 of the second vacuum hot water machine 6 is lower than the heat medium set temperature T3 set in the control device 20, a bypass flow rate is set by a three-way valve constituting the flow control valve 15. Is increased and decreased to the second heat exchanger 5 to control the heat medium temperature of the second vacuum hot water heater 6 to be the heat medium set temperature T3.

  On the contrary, when the measured value of the heat medium temperature by the temperature detector TT2 exceeds the set temperature T3, the bypass flow rate is decreased and the flow rate to the second heat exchanger 5 is increased. In this case, the heat exchange capacity of the second heat exchanger 5 is such that the heat medium H2 of the second vacuum hot water machine 6 can be easily lowered to the heat medium set temperature T3, so that the first vacuum hot water machine 4 It is preferable to select one having a heat exchange capacity larger than the heat exchange amount obtained from the ratio of the heat exchange amount of the second vacuum water heater 6.

  Table 1 below shows a simulation example of the heat balance of the vacuum water heater 1 having the above configuration. Tg1, Tg2, Tw1, and Tw3 in Table 1 below are all assumed values.

  In Table 1, although the exhaust gas temperature (Tg1) of the first vacuum hot water machine outlet is 350 ° C., the heat exchange amount balance between the first vacuum hot water machine 4 and the second vacuum hot water machine 6 is changed by changing this temperature. Can be changed arbitrarily.

  According to the vacuum water heater 1 having the above configuration, it is possible to improve the thermal efficiency as shown in Table 2 below without significantly increasing the heat insulation area as compared with the conventional vacuum water heater. .

  By providing the above configuration, the vacuum water heater 1 can be repaired by replacing only the damaged one when either the first vacuum water heater 4 or the second vacuum water heater 6 is damaged. Therefore, the repair cost can be reduced.

  Moreover, it is possible to change the main material of the 2nd vacuum type hot water machine 6 according to a condition, and the 1st vacuum type hot water machine exit exhaust gas temperature (Tg1) 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. .

  Further, when the vacuum water heater 1 is started, the hot water supply to the second heat exchanger 5 is shut off by the flow rate control valve 15 and all the hot water is supplied from the bypass pipe 14 to the first heat exchanger 3. Thus, it is possible to suppress the generation of condensed water of the exhaust gas G at the quick start-up and when the second vacuum hot water machine 6 is started.

  In the said 1st Embodiment, when the hot water supply load reduces rapidly or interrupts | blocks, the heat-medium temperature of the 2nd vacuum type hot water machine 6 can rise rapidly. At this time, since the temperature of the heating medium of the first vacuum hot water machine 4 also rises, the control device 20 that has received the temperature rise signal from the temperature detector TT1 of the first vacuum hot water machine 4 supplies the amount of fuel supplied to the burner 2 To reduce the amount of combustion of the burner 2. Further, when the temperature of the heat medium of the first vacuum hot water machine 4 rises, the control device 20 stops the combustion of the burner 2.

  In order to mitigate the rapid increase in the temperature of the heat medium of the second vacuum hot water machine 6, as shown in FIG. 3, the vacuum hot water machine 1A of the second embodiment of the present invention is a second vacuum hot water machine. The heating medium temperature set value T2 (T1> T2> T3) for controlling the fuel flow rate is also set on the side 6.

  Then, a control output MV1 for fuel flow rate control calculated by the calculator 21 from the heating medium set temperature T1 of the first vacuum hot water machine 4 and the temperature of the heating medium H1 measured by the temperature detector TT1, and the heating medium The fuel flow control control output MV2 calculated by the calculator 25 from the temperature set value T2 and the temperature of the heating medium H2 measured by the temperature detector TT2 is compared by the comparator 26, and the fuel flow rate is smaller. The control output (MV1 or MV2) is output from the comparator 26 to the fuel flow rate adjusting mechanism 22 to alleviate the rapid temperature rise in the heat medium temperature of the second vacuum water heater 6, and more safely and quickly. Can respond to the hot water supply load.

  The present invention is not construed as being limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A Vacuum type hot water machine 2 Burner 3 1st heat exchanger 4 1st vacuum type hot water machine 5 2nd heat exchanger 6 2nd vacuum type hot water machine 7 Can body 8 Combustion chamber 9 Water pipe 10 Decompression steam chamber 11 Can body 11a Depressurized steam chamber 12 Water pipe group 14 Bypass pipe 15 Flow rate control valve 20 Controllers 21, 23, 25 Calculator 22 Fuel flow rate adjustment mechanism 26 Comparator

Claims (3)

  1. A first vacuum water heater comprising a heat medium heating burner and a first heat exchanger;
    A second vacuum water heater provided with a second heat exchanger and configured to heat the heat medium by the exhaust gas of the first vacuum water heater;
    A bypass pipe for bypassing the second heat exchanger;
    A flow rate control valve for controlling a bypass flow rate through the bypass pipe;
    A control device for controlling the heat medium of the second vacuum hot water machine to a heat medium set temperature lower than the heat medium set temperature of the first vacuum hot water machine by controlling the flow rate control valve ;
    The first heat exchanger is connected to the second heat exchanger so as to be supplied with water from the second heat exchanger.
  2.   The vacuum water heater according to claim 1, wherein the second vacuum water heater is filled with a heat medium having a standard boiling point of less than 100 ° C.
  3. The control device includes: a first control output that controls a fuel flow rate to the burner so that a heat medium of the first vacuum hot water machine reaches a predetermined heat medium set temperature; and Fuel flow rate to the burner so that the heating medium becomes a predetermined heating medium temperature setting value lower than the heating medium setting temperature of the first vacuum hot water machine and higher than the heating medium setting temperature for controlling the flow rate control valve And a fuel flow rate of the burner is controlled by a control output having a smaller fuel flow rate of the first control output and the second control output. The vacuum hot water machine according to claim 1 or 2 .
JP2014059913A 2014-03-24 2014-03-24 Vacuum water heater Active JP6355377B2 (en)

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JP2014059913A JP6355377B2 (en) 2014-03-24 2014-03-24 Vacuum water heater

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JP2014059913A JP6355377B2 (en) 2014-03-24 2014-03-24 Vacuum water heater

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JP6355377B2 true JP6355377B2 (en) 2018-07-11

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Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE756304A (en) * 1969-10-29 1971-03-01 Vaillant Joh Kg Heater operating according to the principle of evaporation under vacuum. (
JPH0256560B2 (en) * 1987-09-11 1990-11-30 Tokyo Gas Co Ltd
JP4553365B2 (en) * 2005-03-25 2010-09-29 株式会社タクマ Hot water / steam combined heat exchanger
JP5406001B2 (en) * 2009-12-16 2014-02-05 昭和鉄工株式会社 Latent heat recovery unit
JP5475425B2 (en) * 2009-12-16 2014-04-16 昭和鉄工株式会社 Hot water generator
JP5604267B2 (en) * 2010-11-08 2014-10-08 株式会社日本サーモエナー Heat recovery apparatus for exhaust gas from vacuum hot water machine and heat recovery method using the same

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