JP5103495B2 - Heating system - Google Patents

Description

  The present invention generates hot water by heating cold water using a heating fluid such as steam as a heat source, and is particularly suitable for applications requiring high-temperature hot water of about 90 ° C. ± 10 ° C. It relates to a heating system that can be used.

  2. Description of the Related Art Conventionally, a hot water supply apparatus that is a type of heating system that generates hot water by heating cold water with steam is known (see Patent Document 1). As shown in FIG. 6, this hot water supply apparatus generates hot water M by heating cold water C with heat of a heating fluid S such as steam by a heat exchanger 60, and cold water C from a water supply source WA. Is led to the heat exchanger 60 by the cold water pipe 61, the heating fluid S from the heating fluid supply source VA is led to the heat exchanger 60 by the heating fluid pipe 62, and the cold water C and the heating fluid S are exchanged by the heat exchanger 60. The hot water M generated by the heat exchange between them is led out from the hot water pipe 63. The heating fluid pipe 62 is provided with a regulating valve 64 for adjusting the passing amount of the heating fluid S flowing inside, and the hot water pipe 63 is provided with a temperature sensor 65 in the vicinity of the outlet side of the heat exchanger 60. ing.

  In the hot water supply device, hot water M is generated by heat exchange between the cold water C from the water supply source WA and the heating fluid S from the heating fluid supply source VA in the heat exchanger 60, and this hot water M is opened by the curan 66. It is taken out by the valve. The heated fluid S after the heat exchange that has passed through the heat exchanger 60 is discharged to the outside from the discharge passage 67 as condensate (drain). In this hot water supply apparatus, the temperature of the hot water M generated by the heat exchanger 60 is detected by the temperature sensor 65, and the temperature information of the detected hot water M is fed back to the control valve 64 by the feedback circuit 68. If the temperature is high, the supply amount of the heating fluid S to the heat exchanger 60 is decreased by restricting the adjustment valve 64. Conversely, if the temperature of the hot water M is low, the supply amount of the heating fluid S is reduced by opening the adjustment valve 64. It is made to increase and the hot water M of predetermined temperature is taken out.

JP 2006-127719 A

  However, in the hot water supply device, the temperature of the hot water M is sensed, and the amount of heating fluid S supplied to the heat exchanger 60 is adjusted by feedback control of the valve opening degree of the control valve 64 based on the temperature. Due to a delay in the response of the temperature sensor 65, a delay in the temperature change of the hot water M with respect to a change in the supply amount of the heating fluid S due to a delay in the transmission of temperature information between the temperature sensor 65 and the control valve 64 that are separated from each other Then, the temperature of the hot water M led out from the heat exchanger 60 may fluctuate repeatedly with a temperature fluctuation range of about 50 ° C., and thus it is difficult to always stably generate the hot water M at the set hot water temperature. .

  Here, when the set hot water temperature of the hot water M taken out from the hot water outlet of the currant 66 is set to a relatively low temperature range of about 40 to 70 ° C., the temperature of the hot water M from the heat exchanger 60 is set as described above. Even if the temperature fluctuates by about 50 ° C., there is no particular problem. That is, since the hot water M in a temperature range of 70 to 120 ° C. higher than the set hot water supply temperature (40 to 70 ° C.) can be derived from the heat exchanger 60, for example, cold water is mixed with the hot water M and the set hot water supply is used. It is possible to adjust so as to obtain hot water having a temperature of 40 to 70 ° C.

  However, when it is desired to obtain hot water having a high set hot water temperature of about 90 ° C. ± 10 ° C. for use in applications such as sterilization and disinfection, for example, in the hot water supply device, the temperature of the hot water M from the heat exchanger 60 is as described above. As described above, there is a case where the temperature fluctuates with a temperature fluctuation range of about 50 ° C. and falls below 80 ° C. which is the minimum temperature of the set hot water supply temperature, so that hot water within the set hot water supply temperature range cannot always be obtained stably. Therefore, it is conceivable to set so that hot water having a temperature of 100 ° C. or higher is derived from the heat exchanger 60 by the temperature control valve. In this case, the temperature of the hot water from the heat exchanger 60 is 100 to 150 ° C. May vary within temperature range.

On the other hand, the pressure of tap water that is the water supply source WA is usually about 0.2 to 0.3 MPa, but may decrease to 0.1 MPa or less when the amount of cold water C used is increased. In this case, on the liquid side (hot water side) of the heat exchanger 60, the hot water M rises to 120 ° C. due to a delay in the response of the temperature sensor 65, so that the saturation pressure rises to 0.1 MPa, and the pressure of the cold water C Because of the above pressure, the cold water C is not supplied to the liquid side of the heat exchanger 60, and the residual water (hot water) in the liquid side of the heat exchanger 60 is heated by the heating fluid S and vaporized. The pressure in the heat exchanger 60 increases excessively . Even if cold water is mixed with the flash steam, not only the hot water M at the set hot water temperature cannot be stably generated, but also an abnormal operation such as an unexpected change in the amount of hot water supplied to the hot water M occurs. Flows back toward the cold water pipe 61 and causes damage to components in the hot water supply apparatus.

Then, this invention aims at providing the heating system which can prevent the pressure of the hot water in a heat exchanger rising too much .

In order to achieve the above object, a heating system according to the present invention includes a heat exchanger that generates hot water by heat exchange between a heating fluid and cold water, and a hot water outlet passage that extracts hot water M from the heat exchanger. A pressure control valve provided in a heating fluid passage for guiding the heating fluid from a heating fluid supply source to the heat exchanger and adjusting a pressure of the heating fluid supplied to the heat exchanger, Is configured to increase the valve opening in response to a decrease in the pressure of the heating fluid from the outlet or the outlet to the heat exchanger inlet or at the heat exchanger outlet, and further, the cold water from the water supply source is A check valve provided in the cold water passage leading to the heat exchanger, and a relief valve provided in the cold water passage between the check valve and the heat exchanger to prevent the pressure in the cold water passage from rising excessively And.

According to this configuration, since the relief valve is provided in the cold water passage between the check valve and the heat exchanger, the pressure in the cold water passage, that is, the pressure of hot water in the heat exchanger is excessively increased. Can be prevented. At the same time, since the valve opening of the pressure control valve is changed according to the pressure of the heating fluid from the outlet or outlet of the pressure control valve to the heat exchanger inlet or at the heat exchanger outlet, the heating fluid to the heat exchanger is changed. Since the supply amount can be controlled independently only within the heating fluid flow system, the amount of heating fluid supplied to the heat exchanger can be controlled without delay in response to the increase or decrease in the amount of hot water supply. The heated water is at a substantially constant temperature. Therefore, for example, even when hot water having a high temperature of about 90 ° C. ± 10 ° C. is generated, hot water at the set hot water supply temperature can always be generated stably.

According to the heating system of the present invention , a relief valve is provided in the cold water passage between the check valve and the heat exchanger, and the pressure in the cold water passage, that is, the pressure of hot water in the heat exchanger increases excessively. Can be prevented.

It is a distribution diagram showing the heating system concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view which shows the valve closing state of the pressure control valve of a heating system same as the above. It is a longitudinal cross-sectional view which shows the valve opening state of a pressure control valve same as the above. It is a systematic diagram which shows the heating system which concerns on 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the valve closing state of the pressure control valve of a heating system same as the above. It is a systematic diagram of the conventional heating system.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing a heating system 10A according to the first embodiment of the present invention. The heating system 10A of this embodiment can be applied to the use of supplying hot water having a high temperature of 90 ° C. ± 10 ° C., and heats the cold water C that is the fluid to be heated by the heat of the heating fluid S such as saturated steam. The heat exchanger 11 which produces | generates the hot water H of high temperature is provided. The heat exchanger 11 is called a plate heat exchanger in which, for example, a plurality of plates are stacked, and a passage of a heating fluid S and a passage of cold water C (not shown) are alternately arranged therebetween via the plates. However, it is preferable because of its small size and relatively large heat exchange capacity.

  The heating system 10A is supplied from a cold water passage 12 that guides cold water C supplied from an external water supply source (for example, tap water) WA to the heat exchanger 11 and a heating fluid supply source (for example, a boiler) VA. The heating fluid passage 13 that guides the heating fluid S such as saturated steam to the heat exchanger 11, the hot water outlet passage 14 that guides the hot water H generated by the heat exchanger 11, and the heat exchanger 11 pass through. And a condensate discharge passage 15 for discharging the heated heating fluid S as condensate (drain).

  A pressure regulating valve 17A is disposed in the heating fluid passage 13, and the pressure regulating valve 17A increases the valve opening according to the decrease in the pressure of the heating fluid S at the outlet 50 thereof, that is, The pressure of the heating fluid S from the heating fluid supply source VA is adjusted to the set pressure by feedback control based on the outlet pressure, and then supplied to the heat exchanger 11.

  A hot water mixing valve 44 is disposed in the hot water outlet passage 14 through which the hot water H is led out from the heat exchanger 11, and the hot water mixing valve 44 supplies water to the hot water H from the heat exchanger 11. Cold water C from WA is mixed, hot water M adjusted to a desired set hot water supply temperature is generated, and hot water is supplied through a hot water supply valve (curan) 24 serving as a hot water supply outlet. In addition, since the heating system 10A of this embodiment supplies hot water M having a high temperature of 90 ° C. ± 10 ° C. as described above, the heat exchanger 11 generates hot water H having a temperature of 100 ° C. or higher. Thus, the water is led out to the hot water lead-out passage 14. Therefore, in the following description, for convenience of explanation, hot water of 100 ° C. or higher derived from the hot water outlet passage 14 is referred to as “hot water H” and is distinguished from the hot water M having a set hot water temperature extracted from the hot water supply valve 24. To clarify.

  Further, check valves 31 and 32 are respectively arranged at locations upstream of the heat exchanger 11 in the cold water bypass passage 42 and the cold water passage 12 branched from the cold water passage 12 to the hot water mixing valve 44. Yes. Further, the condensate discharge passage 15 has a function of closing the valve when the pressure of the heating fluid S discharged from the heat exchanger 11 exceeds a predetermined pressure to prevent the discharge of the heating fluid S. A well-known steam trap 33 is provided. The predetermined pressure is set to a pressure higher than the set pressure (0.05 to 0.06 MPa) of the pressure setting valve 17A and lower than the predicted minimum pressure (0.1 MPa) of the cold water C, for example, 0.1 MPa. Yes. In this embodiment, a mechanical steam trap 33 is used, and when the pressure exceeds a predetermined pressure, the valve closing force of the valve body in the steam trap 33 rises and becomes a closed state. In the cold water discharge passage 34 branched from the portion between the check valve 32 and the heat exchanger 11 in the cold water passage 12, the hot water M from the hot water supply valve 24 is stopped when the hot water M is taken out. A relief valve 35 for preventing the pressure of the hot water H from rising excessively is provided.

  Next, a specific structure of the pressure control valve 17A will be described with reference to FIG. FIG. 2 shows a closed state of the pressure control valve 17A. The pressure control valve 17A has an upper cover 19 connected to the upper end opening of the case body 18, and the inside of the case body 18 has a partition wall. The upper pressure receiving chamber 21 and the lower heating fluid passage 13 are partitioned by the portion 18a. The outlet side of the heating fluid passage 13, that is, the downstream side of the valve body 28 described later and the pressure receiving chamber 21 are communicated with each other via a small-diameter communication hole 18 b formed in the partition wall portion 18 a, and The pressure of the heating fluid S is applied to the pressure receiving chamber 21. The pressure control valve 17A is configured to supply the heating fluid S, which is saturated steam supplied at a pressure of 0.2 to 0.5 MPa from the heating fluid supply source VA (FIG. 1), to 0.1 MPa that is the predicted minimum pressure of the cold water C. The pressure is adjusted to a lower set pressure of 0.05 to 0.06 MPa and is allowed to flow out.

  A lower cover 20 that seals a lower end opening is connected to a lower end portion of the case body 18, and a valve chamber 22 that forms a part of the heating fluid passage 13 is formed by the case body 18 and the lower cover 20. A dust removing screen 16 is arranged in the valve chamber 22. A casing 25 is formed by the case body 18, the upper cover 19 and the lower cover 20. A cylindrical support portion 18c formed at the central portion of the partition wall portion 18a is slidable with a valve rod 26 extending in the vertical direction and having an upper end portion and a lower portion located in the pressure receiving chamber 21 and the heating fluid passage 13, respectively. The valve body 28 disposed in the valve chamber 22 at the lower end of the valve rod 26 is a return spring 27 comprising a compression coil spring mounted between the valve body 28 and the lower cover 20. It is contacted by. The valve body 28 is located on the inner side (downstream side) of the screen 16 to prevent foreign matters such as scales and dust from entering. Further, the valve body 28 for opening and closing the heating fluid passage 13 is pressed by the return spring 27 against the valve opening of the valve seat member 23 provided in the heating fluid passage 13 to be closed, and when the valve rod 26 is moved downward. By being pushed down and separated from the valve seat member 23, the valve is opened.

  An attachment member 29 is sandwiched and fixed at a connection portion between the case main body 18 and the upper cover 19 of the casing 25, and a pressure receiving member 30 made of a bottomed cylindrical bellows is supported by the attachment member 29 in a suspended state. ing. The pressure receiving chamber 21 is formed outside the pressure receiving member 30 by the case body 18, the attachment member 29, and the pressure receiving member 30. The lower end portion of the pressure receiving member 30 is opposed to the upper end surface of the valve rod 26.

  The operation member 37 covering the outer peripheral surface of the upper cover 19 is supported by an upper end portion of the upper cover 19 so that an adjustment shaft 38 extending vertically through the upper cover 19 is rotatably supported. The body 38 is connected to rotate integrally. A male screw portion 38a is formed at an upper portion in the upper cover 19 of the adjustment shaft body 38, and a nut-like pressure setting member 39 is screwed into the male screw portion 38 in a state where the nut-shaped pressure setting member 39 is prevented from rotating. Between the pressure setting member 39 and the spring receiving member 40 disposed at the bottom of the bottomed cylindrical pressure receiving member 30, a pressure setting spring 41 including a compression coil spring is interposed. Therefore, when the operation member 37 is rotated, the adjustment shaft body 38 is rotated integrally with the operation member 37, and the pressure setting member 39 screwed into the male screw portion 38a of the adjustment shaft body 38 is engaged with the male screw portion 38a. The pressure force of the pressure setting spring 41 is changed by moving the pressure setting spring 41 in the vertical direction, and the force of the pressure receiving member 30 acting in the contraction direction by the pressure of the pressure receiving chamber 21 and the spring force of the pressure setting spring 41 and the return spring 27. By changing the opening degree of the valve body 28 according to the balance, the set pressure of the pressure control valve 17A described above can be adjusted.

  Next, the operation of the heating system 10A will be described. In this heating system 10A, the set pressure of the pressure control valve 17A is set in advance prior to operation. A specific means for adjusting the set pressure will be described. As described above, saturated steam having a pressure of 0.2 to 0.5 MPa is supplied as the heating fluid S from the heating fluid supply source VA, and tap water having a pressure of 0.2 to 0.3 MPa is supplied from the water supply source WA. Is supplied as cold water C, but when tap water is used, tap water may drop to near 0.1 MPa. It is assumed that 3 MPa. Therefore, in this embodiment, the set pressure of the pressure control valve 17 is adjusted to 0.05 to 0.06 MPa, which is lower than 0.1 MPa, which is the predicted minimum pressure of the cold water C. Thereby, the pressure adjusting valve 17A adjusts the heated fluid S supplied at a pressure of 0.2 to 0.5 MPa to a set pressure of 0.05 to 0.06 MPa, that is, reduces the pressure to flow out.

  When the hot water M with the hot water supply valve 24 of FIG. 1 closed is not used, the consumption amount of the heating fluid S is only the heat radiation of the heat exchanger 11 and the outlet side piping of the pressure control valve 17A. Become. The set pressure is adjusted to 0.05 to 0.06 MPa by the pressure control valve 17A with a slight consumption amount of the heating fluid S. That is, the valve body 28 of the pressure control valve 17A in FIG. 2 adjusts the valve opening to the slightly open state so that the heating fluid S is slightly consumed, and the set pressure is maintained constant.

  When the hot water supply valve 24 in FIG. 1 is opened, the cold water C from the water supply source WA flows into the heat exchanger 11 through the cold water passage 12, and the heating fluid S is consumed in the heat exchanger 11, that is, Since the heat energy of the heating fluid S is transmitted to the cold water C and consumed, the pressure of the heating fluid S on the outlet side of the pressure control valve 17A decreases, and this pressure decrease is caused by the pressure receiving chamber 21 through the communication hole 18b of FIG. Acting on the pressure receiving member 30 to reduce the pushing force of the pressure receiving member 30. Therefore, the spring receiving member 40 is lowered while the pressure receiving member 30 is extended downward by the spring force of the pressure adjusting spring 41 and pushes down the valve rod 26. Therefore, as shown in FIG. 3, the valve body of the pressure adjusting valve 17A The opening 28 is increased, and the heating fluid S flows out from the outlet 50 through the heating fluid passage 13 in the pressure control valve 17A and is supplied to the heat exchanger 11 in FIG.

  Heat exchange between the heating fluid S led to the heat exchanger 11 and the cold water C led to the heat exchanger 11 through the cold water passage 12 generates hot water H having a temperature higher than the set hot water supply temperature. Hot water H is supplied to the hot water mixing valve 44 through the hot water outlet passage 14. In the hot water mixing valve 44, the hot water H is mixed with the cold water C supplied through the bypass passage 42 to generate hot water M at a set hot water supply temperature. At this time, the hot water / water mixing valve 44 automatically adjusts the valve opening degree of the inflow valve port for the cold water C and the valve opening degree of the inflow valve port for the hot water H so that the temperature sensing part becomes the set hot water supply temperature. Thus, the hot water M that has reached the set hot water supply temperature is taken out from the hot water supply valve 24. Here, since the set pressure 0.05 to 0.06 MPa of the pressure control valve 17A is set to the predicted minimum pressure 0.1 MPa or less of the cold water C, it is in the liquid side (hot water side) of the heat exchanger 11. The temperature is a saturation temperature of 0.05 to 0.06 Mpa at the maximum value. That is, since the pressure in the liquid side (hot water side) of the heat exchanger 11 is equal to or lower than the saturation pressure of 0.1 Mpa, it is lower than the predicted minimum pressure of the cold water C, and therefore the supply of cold water is not shut off. Since the residual water is not vaporized by heating the fluid S, there is no possibility that abnormal operation will occur due to the generation of flash vapor on the liquid side.

  Here, when the hot water supply valve 24 is opened to a large valve opening for the purpose of using a relatively large amount of hot water M, the consumption amount of the heating fluid S in the heat exchanger 11 increases, so the pressure control valve 17A. The pressure of the heating fluid S on the outlet side of the pressure decreases, the difference between the pressing force by the pressure setting spring 41 in FIG. 3 and the pressing force by the pressure receiving member 30 increases, and the opening degree of the valve body 28 further increases. A larger amount of heating fluid S is supplied to the heat exchanger 11 of FIG. The pressure control valve 17A feeds back the change in the pressure of the heated fluid S on the outlet side to adjust the valve opening of the valve body 28. Therefore, when the consumption amount of the heated fluid S increases due to the amount of hot water M used, By increasing the opening degree of the valve body 28, control is performed to suppress the amount of decrease in the pressure of the heating fluid S on the outlet side. When the hot water supply valve 24 is throttled to a small valve opening from this state, the pressure control valve 17A performs the reverse operation to the above, and the opening of the valve body 28 in FIG. The pressure of the heating fluid S on the outlet side is kept at the set pressure.

  In this way, the heating system 10A in FIG. 1 changes the opening degree of the pressure control valve 17A in accordance with the increase or decrease in the flow rate of the hot water M taken out from the hot water supply valve 24, and thereby the heating fluid S to the heat exchanger 11 is changed. Increase or decrease the supply.

  In this heating system 10A, adjustment of the supply amount of the heating fluid S to the heat exchanger 11 is arranged in the heating fluid passage 13 without using the temperature of the hot water H generated in the heat exchanger 11 as control information. The valve opening degree of the provided pressure control valve 17A is controlled by feedback control based on the pressure of the heating fluid S on the outlet side of the pressure control valve 17A. That is, the supply amount of the heating fluid S to the heat exchanger 11 is controlled independently only within the flow system of the heating fluid S. For this reason, the control valve is feedback-controlled based on the temperature information in the hot water system as in the conventional heating system, so that there is a delay in sensing the hot water temperature, a delay in the temperature change of the hot water with respect to the heating fluid supply amount change, etc. Unlike what is generated, in this heating system 10A, the supply amount of the heating fluid S to the heat exchanger 11 can be controlled without a time delay corresponding to the increase or decrease of the amount of use of the hot water M, and The heating fluid S can be quickly controlled so that the pressure of the heating fluid S always becomes the set pressure of the pressure control valve 17A. In particular, the pressure control valve 17A of this embodiment is configured as an internal detection type that feeds back the pressure of the heating fluid S on the outlet side of the heating fluid passage 13 to the pressure receiving chamber 21 through the communication hole 18b provided in the casing 25 of FIG. Therefore, the supply amount and pressure of the heating fluid S can be adjusted almost without time delay.

  Further, in the heat exchanger 11, regardless of the supply amount of the heating fluid S, the heating fluid S that is a saturated steam adjusted to the set pressure of the pressure control valve 17A, 0.05 to 0.06 MPa is always supplied. Therefore, while being able to produce | generate the hot water H of 110 degreeC vicinity which is the saturation temperature of the saturated steam, the supply amount of the heating fluid S can be controlled without time delay according to the increase / decrease in the amount of hot water supply as mentioned above. Although the pressure of the heating fluid S set in the pressure control valve 17A is reduced by the increase in the amount of hot water supply, the valve opening is stabilized by feedback control based on the pressure. Stable and generated hot water H is also stabilized near the saturation temperature of the reduced pressure. Thus, since the temperature of the hot water H can be maintained sufficiently higher than the set hot water supply temperature 90 ° C., when the hot water supply amount reaches the maximum flow rate, the hot water H also becomes the maximum flow rate and causes a temperature drop. The temperature of the hot water H when the flow rate is reached does not fall below the set hot water supply temperature 90 ° C. Thereby, the hot water mixing valve 44 for high temperature can always produce | generate the hot water M of high temperature 90 degreeC +/- 10 degreeC which is preset hot water supply temperature stably.

  By the way, in this heating system 10A, for some reason, for example, when a failure occurs such that the valve body 28 of the pressure control valve 17A in FIG. As a result, the pressure of the pressure adjusting valve 17A in FIG. 1 is no longer reduced. As a result, the pressure of the heating fluid S supplied to the heat exchanger 11 rises above the pressure of the cold water C, and flash steam is generated on the liquid side of the heat exchanger 11. The occurrence of such a situation is expected. On the other hand, in this embodiment, the valve closing pressure of the steam trap 33 is set to a constant value of 0.1 MPa that is lower than the pressure of the cold water C and slightly higher than the set pressure of the pressure regulating valve 17A.

  Therefore, the steam trap 33 is opened and restored because the pressure of the heating fluid S in the condensate discharge passage 15 is 0.1 MPa or less during normal operation of the pressure control valve 17A. Condensate in the water discharge passage 15 is discharged to the outside. On the other hand, when the above-described failure occurs in the pressure control valve 17A, the pressure control valve 17A is kept in the open state, and the high pressure, heated fluid S of 0.2 to 0.5 MPa is applied to the heat exchanger. 11 and reaches the condensate discharge passage 15. Thereby, the steam trap 33 closes and the flow of the heating fluid S is stopped. Therefore, since large heat energy of the heating fluid S is prevented from being transmitted to the cold water C in the heat exchanger 11, it is possible to prevent a large amount of flash steam from being generated on the liquid side of the heat exchanger 11.

  When the flow of the heating fluid S stops in this way, the temperature of the heating fluid S in the condensate discharge passage 15 decreases due to natural heat dissipation, and when the pressure decreases to a set pressure of 0.1 MPa or less along with this, the steam trap 33. Opens, that is, returns to the normal state. Therefore, if the failure of the pressure control valve 17A is corrected during that time, the heating system 10A can immediately start normal operation. In this way, even if the pressure control valve 17A fails and an abnormal operation occurs, the steam trap 33 is immediately closed to prevent flash steam from being generated on the liquid side of the heat exchanger 11. Therefore, it is possible to prevent the occurrence of damage to the components in the system due to the backflow of the flash steam, and to protect the hot and cold mixing valve 44.

  The outlet pressure used for feedback control of the pressure control valve 17A is a portion of the heating fluid passage 13 from the valve body 28 to the outlet 50 of the pressure control valve 17A and a portion from the outlet 50 to the inlet of the heat exchanger 11. Since it is equal to the pressure, it may be detected from any location of these parts.

  FIG. 4 is a system diagram showing a heating system 10B according to the second embodiment of the present invention, and FIG. 5 is a longitudinal sectional view showing a closed state of the pressure regulating valve 17B of the heating system 10B. In these drawings, the same or corresponding parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted. This heating system 10B is different from the first embodiment in that feedback is based on the pressure of the heating fluid S on the downstream side of the heat exchanger 11 in FIG. 4 in place of the internal detection type pressure control valve 17A of the first embodiment. This is because an external detection type pressure control valve 17B that performs control is used. For this purpose, the condensate discharge passage 15 and the pressure receiving chamber 21 of the pressure control valve 17B in FIG. . The set pressure of the pressure control valve 17B is, for example, 0.05 to 0.06 MPa, as in the first embodiment.

  Since this heating system 10B basically operates in the same manner as in the first embodiment, only the operation different from that in the first embodiment will be described. When the hot water M is not used, the consumption amount of the heating fluid S is only the heat radiation of the heat exchanger 11 and the outlet side piping of the pressure control valve 17A, so that the amount is small and the condensate discharge downstream of the heat exchanger 11 is discharged. The pressure of the heating fluid S in the passage 15 is maintained at 0.05 to 0.06 MPa, which is the set pressure of the pressure control valve 17B. Therefore, the valve opening degree of the pressure control valve 17B that feeds back this pressure is slightly opened.

  When the hot water supply valve 24 is opened and the hot water M is used, if the hot water supply amount from the hot water supply valve 24 is about 50% or less of the maximum hot water supply amount, the heating fluid inlet in the small capacity type heat exchanger 11 is used. The pressure on the side of the heating fluid and the outlet side of the heating fluid are substantially the same, but when the amount of hot water supply is about 50% or more of the maximum hot water supply amount, the heating fluid S increases with the exchange heat amount in the heat exchanger 11. Therefore, as described in the first embodiment, the temperature and pressure of the heating fluid S in the heat exchanger 11 are reduced. The heating fluid S that is saturated steam that passes through the heat exchanger 11 has a liquid component that increases as the pressure decreases, and is susceptible to flow resistance, resulting in a pressure loss. Therefore, the heating fluid outlet of the heat exchanger 11 Side pressure, that is, the pressure in the condensate discharge passage 15 is lower than the inlet side of the heat exchanger 11.

  Since the pressure in the condensate discharge passage 15 thus greatly reduced is transmitted to the pressure receiving chamber 21 (FIG. 5) of the pressure regulating valve 17B through the pressure detection pipe 36, the pushing force of the pressure receiving member 30 is greatly reduced. Since the pressure receiving member 30 can be extended downward by the spring force of the pressure adjusting spring 41 by the greatly reduced pushing force, the valve opening degree of the pressure adjusting valve 17B is the internal detection type of the first embodiment. It becomes larger than the pressure control valve 17A. That is, as the pressure detected in the pressure receiving chamber 21 is lower, the opening degree of the valve body 28 is increased, and the flow rate of the heating fluid S can be increased. Therefore, by using the control method of the pressure control valve 17B of FIG. 5, the flow rate of the heating fluid S that can flow into the heat exchanger 11 increases, so the amount of hot water M supplied increases and the capacity increases. In order to increase the pressure drop in the heat exchanger 11, it is preferable to use a small capacity heat exchanger 11.

  When the hot water supply amount of the hot water M increases, the flow rate of the heating fluid S increases as the valve opening of the pressure control valve 17B increases due to the decrease of the outlet side pressure of the heat exchanger 11, so the inlet of the heat exchanger 11 The side pressure (that is, the pressure on the downstream side of the heating fluid passage 13) may be higher than the set pressure of the pressure control valve 17B. However, since the pressure receiving chamber 21 and the heating fluid passage 13 of FIG. 5 are separated from each other by the partition wall portion 18a of the case body 18, the pressure regulating valve 17B is downstream of the heating fluid passage 13 that has risen above the set pressure. The pressure of the heating fluid S on the downstream side of the heat exchanger 11 is low because the pressure of the heating fluid S on the side does not act to apply a force in the valve closing direction to the pressure receiving chamber 21. By continuing to act on the pressure receiving chamber 21, a large valve opening is kept, so the flow rate of the heating fluid S does not decrease. Note that an O-ring (not shown) is attached to a sliding surface portion between the valve stem 26 and the support portion 18c, so that air tightness and liquid tightness between the pressure receiving chamber 21 and the downstream side 13 of the valve body 28 are provided. It is secured. Such an airtight structure is also appropriately employed in the pressure control valve 17A in FIG.

  In general, the pressure receiving direct acting type pressure regulating valve 17B used in this embodiment, in which the pressure receiving member 30 directly operates the valve body 28, receives the supply pressure from the pilot valve by the drive unit and receives the main valve body. Compared to the type of pressure control valve that operates, there is a merit such as low cost, few failures and good maintainability. However, since the pressure of the heating fluid S is reduced and derived, the flow rate of the heating fluid S is increased. There is a disadvantage that cannot be done. In addition, when a heat exchanger having a sufficient capacity with respect to the maximum hot water supply amount of this embodiment is used, heat exchange is performed even if the hot water supply amount is 50% or more of the maximum hot water supply amount of the embodiment. Since the amount of heat exchanged in the chamber is small, the pressure of the heating fluid S at the inlet side and the outlet side of the heat exchanger hardly changes, whereas the small capacity type heat exchanger used in this embodiment has a maximum When it becomes 50% or more of the hot water supply amount, the pressure of the heating fluid S on the outlet side decreases with respect to the inlet side of the heat exchanger. Accordingly, the heating system 10B of this embodiment uses the pressure receiving direct acting type pressure control valve 17B and the small capacity type heat exchanger 11, thereby reducing the size and cost of the heating fluid S. Since there is an advantage that it can be used for a large flow rate of the heating fluid S by generating a large pressure drop, it can be suitably used for applications in which a large amount of hot water M is used.

10A, 10B Heating system 11 Heat exchanger 13 Heating fluid passage 14 Hot water outlet passage 17A, 17B Pressure regulating valve 44 Hot water mixing valve S Heating fluid C Cold water M Hot water VA Heating fluid supply source WA Water supply source

Claims (1)

A heat exchanger 11 that generates hot water M by heat exchange between the heating fluid S and cold water C;
A hot water outlet passage 14 for leading the hot water M from the heat exchanger 11;
A pressure adjusting valve 17A provided in the heating fluid passage 13 for guiding the heating fluid S from the heating fluid supply source VA to the heat exchanger 11 and adjusting the pressure of the heating fluid S supplied to the heat exchanger 11; Prepared,
The pressure control valve 17A is configured to increase the valve opening according to a decrease in the pressure of the heating fluid S from the outlet or outlet to the heat exchanger inlet or at the heat exchanger outlet,
A check valve 32 provided in the cold water passage 12 for guiding the cold water C from the water supply source WA to the heat exchanger 11;
A heating system comprising a relief valve 35 provided in the cold water passage 12 between the check valve 32 and the heat exchanger 11 to prevent the pressure in the cold water passage 12 from rising excessively.

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