JP2018059667A - Internal circulation type hot water system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal circulation type hot water system in which the rise time at the start of hot water supply is short.SOLUTION: An internal circulation type hot water system comprises: a heat exchanger 2 for creating hot water by heat exchange between steam and cold water; a steam control valve 3 for regulating the steam supply amount to the heat exchanger 2; a tank 4 for accumulation the cold water introduced into the heat exchanger 2; a return passage 5 for returning a part of the hot water from the heat exchanger 2 to the tank 4; an adjusting valve 29 provided in the return passage 5 for adjusting the aperture of the passage; a hot water temperature sensor 30 for detecting the temperature of the hot water; temperature control means 34 for adjusting the aperture of the steam control valve 3 so that the hot water temperature detected by the hot water temperature sensor 30 becomes a preset temperature; and aperture suppression means 35 for reducing the aperture of the adjusting valve 29 until the hot water temperature detected at the start of operation reaches the preset temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hot water supply system for producing hot water by mixing steam and cold water, and more particularly to an improvement of an internal circulation type hot water supply system.

  2. Description of the Related Art Conventionally, a hot water production apparatus that produces hot water by mixing steam and cold water is known as one that can easily obtain hot water using a steam source that is often installed in a factory. Among such hot water production apparatuses, there is one that employs an internal circulation hot water supply system in order to stabilize the hot water supply temperature and prevent an excessive pressure rise in the piping (for example, Patent Document 1). This internal circulation hot-water supply system is configured to generate hot water by exchanging heat between steam supplied from a steam source and cold water supplied from a water supply source using a heat exchanger, and a part of the hot water from the heat exchanger is generated. A return passage returning to the cold water storage tank is added.

JP-A-6-201188

  In the hot water producing apparatus of the internal circulation hot water supply type as disclosed in Patent Document 1, a fixed orifice is provided in a warm water return passage, and a part of the warm water is passed through the fixed orifice and returned to the storage tank. There is something. In this configuration, when the circulating flow rate of hot water returned from the return passage to the cold water storage tank increases, the circulating water is also added under conditions where the required heat quantity increases (for example, when the set temperature of hot water is high or the hot water supply flow rate is high). Since the water supply temperature cannot be raised directly to the set temperature, the water whose temperature has risen to a certain level returns from the fixed orifice into the storage tank, and slowly raises the water temperature in the tank. As a result, the hot water supply temperature is raised to the set temperature. For example, when the ratio of the internal circulation (return flow rate) is 1 with respect to the hot water supply flow rate 2, when the hot water supply flow rate is changed from 2 to 1, the flow rate flowing into the heat exchanger is reduced by half if there is no internal circulation. However, when there is an internal circulation, the hot water supply flow rate as a whole decreases from 3 to 2, so the rate of decrease in the flow rate flowing into the heat exchanger is reduced, so that the temperature stability is improved.

  However, when hot water supply is started on the user load side, it takes a long time to obtain hot water reaching the set temperature, and there is a problem that the quick response is low.

  An object of the present invention is to provide an internal circulation type hot water supply system that has a short rise time when starting hot water supply on the user load side and is highly responsive.

  In order to achieve the above object, an internal circulation hot water supply system according to the present invention includes a heat exchanger that generates hot water by heat exchange between steam and cold water, and steam control that adjusts the amount of steam supplied to the heat exchanger. A valve, a tank for storing the cold water introduced into the heat exchanger, a return passage for returning a part of the hot water from the heat exchanger to the tank, and an opening degree of the passage provided in the return passage An adjusting valve for adjusting the temperature, a hot water temperature sensor for detecting the temperature of the hot water, and a temperature adjusting means for adjusting the opening of the steam control valve so that the hot water temperature detected by the hot water temperature sensor becomes a set temperature; And an opening degree suppression means for reducing the opening degree of the regulating valve until the hot water temperature detected at the start of operation reaches a set temperature.

  According to this configuration, at the start of operation, the temperature of the hot water from the heat exchanger is detected by the hot water temperature sensor, and the temperature of the hot water detected by the hot water temperature sensor is adjusted by the temperature adjustment means by adjusting the opening of the steam control valve. The temperature can be controlled to be the set temperature. At this time, until the hot water supply temperature reaches the set temperature, the opening degree of the return passage is narrowed down by the opening degree suppression means so that the internal circulation flow rate becomes zero or a small amount. It can be obtained in time and has excellent responsiveness. When the hot water temperature detected at the start of operation reaches the set temperature, the opening degree of the regulating valve is gradually opened by the opening degree suppressing means, so that the internal circulation flow rate is gradually changed with almost no change in the hot water supply temperature. Since it can be increased, the stability of the hot water supply system is improved.

  In the internal circulation hot water supply system of the present invention, desirably, a hot water supply passage for supplying hot water from the heat exchanger to an external load is provided with a hot water supply adjustment valve and a check valve located upstream thereof, The return passage is branched from between the hot water supply adjustment valve and the check valve in the hot water supply passage. According to this configuration, the hot water supply passage between the hot water supply adjustment valve and the check valve is filled with hot water, and since this hot water does not flow back to the upstream side from the check valve, there is no remaining hot water. Warm water can be reliably returned to the tank.

  The internal circulation hot water supply system according to the present invention further preferably includes temperature setting means for setting the set temperature by an external input operation. According to this configuration, since the user can input an arbitrary set temperature from the outside to the temperature setting means, it can be easily input and set, and the operability is excellent.

  According to the present invention, until the hot water supply temperature reaches the set temperature at the start of operation, the opening degree of the adjustment valve provided in the return passage is narrowed down by the opening degree suppression means. It can be obtained with a short rise time and has excellent responsiveness. When the hot water temperature detected at the start of operation reaches the set temperature, the opening degree of the regulating valve is gradually opened by the opening degree suppressing means, so that the internal circulation flow rate is gradually changed with almost no change in the hot water supply temperature. Since it can be increased, the stability of the hot water supply system is improved.

It is a lineblock diagram showing the internal circulation type hot-water supply system concerning one embodiment of the present invention. It is the graph which compared the rise time until it reaches set temperature at the time of operation of the internal circulation type hot-water supply system and the conventional hot-water supply system.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram showing an internal circulation hot water supply system according to an embodiment of the present invention. As shown in the figure, this internal circulation hot water supply system 1 includes a heat exchanger 2 that generates hot water by heat exchange between steam and cold water, and a steam control valve that adjusts the amount of steam supplied to the heat exchanger 2. 3, a tank 4 for storing the cold water introduced into the heat exchanger 2, and a return passage 5 for returning a part of the hot water from the heat exchanger 2 to the tank 4.

  Steam is introduced into the heat exchanger 2 through the steam passage 6, and the steam passage 6 is provided with a manual on-off valve 8, a foreign matter removal strainer 9, and a vapor pressure sensor 10, and downstream of the foreign matter removal strainer 9. One branch passage 6 </ b> A branched at is connected to the heat exchanger 2, and the steam control valve 3 is provided on the upstream side of the heat exchanger 2. A steam trap 7 is provided on the downstream side of the other branch passage 6B, and is discharged to the outside together with the drain from the steam trap 11 provided in the heat exchanger 2.

  A water supply passage 12 such as a water supply pipe is disposed on the upper side of the tank 4, and water (cold water) is introduced into the tank 4 through the water supply passage 12. A manual open / close valve 13 is provided in the water supply passage 12. And a ball tap 14 are provided. The ball tap 14 controls the opening degree of the water supply passage 12 so that the displacement of the ball 14a due to the vertical movement of the tank water surface opens and closes the valve at the lever base, and the amount of water in the tank 4 becomes a constant amount. Similarly, on the upper side of the tank 4, an external circulation passage 16 for returning used or surplus hot water on the user side to the tank 4 is provided. The external circulation passage 16 also includes a manual opening / closing valve 17, a falling water A prevention valve 18 is provided.

  Further, a water supply passage 20 is provided between the lower side of the tank 4 and the heat exchanger 2, and a foreign substance removal strainer 21, a pump 22 and a flow meter 23 are provided in the water supply passage 20 from the upstream side. A temperature sensor 24 is provided between the pump 22 and the flow meter 23. The temperature sensor 24 measures the temperature of the water introduced from the tank 4 to the heat exchanger 2 by the pump 22 and inputs information on the measured value to the controller 33 described later. The flow meter 23 measures the flow rate of water introduced from the tank 4 to the heat exchanger 2 by the pump 22, and information on the measured value is input to the controller 33.

  A hot water supply passage 25 that supplies hot water from the heat exchanger 2 to an external load is provided between the heat exchanger 2 and the hot water supply side that is a user load. Manual hot water supply adjustment is provided downstream of the hot water supply passage 25. A check valve 27 is provided on the upstream side of the valve 26. The return passage 5 is branched from the hot water supply adjustment valve 26 and the check valve 27 in the hot water supply passage 25, and the discharge port at the tip of the return passage 5 faces the upper side of the tank 4. The return passage 5 is provided with an adjustment valve 29 that can adjust the opening degree of the passage. The adjusting valve 29 can arbitrarily adjust the opening degree of the return passage 5 from fully open to fully closed by a command 29a output from the controller 33 described later. A hot water temperature sensor 30 for measuring the hot water temperature and a pressure sensor 31 for measuring the hot water pressure are respectively provided between the hot water supply adjustment valve 26 and the check valve 27 in the hot water supply passage 25. Measurement values obtained by the hot water temperature sensor 30 and the pressure sensor 31 are also input to the controller 33 as information.

  This internal circulation type hot water supply system 1 has a controller 33 which is a control operation panel for effectively operating the hot water supply system. The controller 33 detects the temperature of hot water detected by the hot water temperature sensor 30 in the hot water supply passage 25. Temperature adjusting means 34 for adjusting the opening degree of the steam control valve 3 so that becomes the set temperature, and the adjusting valve 29 of the return passage 5 until the temperature of the hot water detected by the hot water temperature sensor 30 at the start of operation reaches the set temperature. Is provided with opening degree suppression means 35 for reducing the opening degree and temperature setting means 36 for setting the temperature of the hot water to an arbitrary set temperature by an external input operation. The temperature adjustment unit 34 and the opening degree suppression unit 35 are configured by a digital arithmetic unit or an analog electronic circuit. The temperature setting means 36 is an analog type dial as shown in the drawing, but may be a digital type touch panel operation button. The set temperature is appropriately selected according to the application, such as 60 ° C., 70 ° C., or 90 ° C., for example.

  Operation | movement of the internal circulation type hot water supply system 1 comprised in this way is demonstrated. When the hot water supply operation is started, cold water (such as tap water) is introduced into the upper part of the tank 4 through the water supply passage 12 on the water supply side, and is led out from the lower part of the tank 4 toward the heat exchanger 2 by the pump 22. The On the other hand, on the steam side, the steam is introduced into the heat exchanger 2 from the branch path 6 </ b> A through the steam path 6. In this heat exchanger 2, hot water is generated by heat exchange between steam and cold water. This hot water passes through the hot water supply passage 25 and is supplied to the user load side. The amount of hot water supply is adjusted by opening the hot water supply adjustment valve 26 appropriately. At this time, until the hot water supply temperature reaches the set temperature, the opening degree of the adjusting valve 29 provided in the return passage 5 branched from the hot water supply passage 25 is closed by the opening degree suppression means 35 of the controller 33, or is narrowed down. When the opening degree of the regulating valve 29 is reduced to a small value, a part of the hot water from the heat exchanger 2 returned to the tank 4 from the return passage 5 is returned to the tank 4 with a small flow rate. As a result of the decrease, the hot water supply state can be maintained with little influence on the hot water supply temperature and flow rate of hot water.

  During this series of operations, the vapor pressure introduced from the vapor passage 6 into the heat exchanger 2 is measured by the vapor pressure sensor 10 and the measured value is input to the controller 33 as information. These measured values are calculated by the temperature adjusting means 34 of the controller 33. Based on the calculated values, the controller 33 issues a control command to the steam control valve 3, and the hot water discharged from the heat exchanger 2 to the hot water supply passage 25. The steam supply amount to the heat exchanger 2 is adjusted by adjusting the opening degree of the steam control valve 3 so that becomes the set temperature.

  When the temperature of the hot water temperature detected at the start of operation reaches the set temperature, the opening degree of the adjustment valve 29 provided in the return passage 5 branched from the hot water supply passage 25 is gradually opened by the opening degree suppression means 35 of the controller 33. To do. Thereby, the internal circulation amount of the hot water from the return passage 5 to the tank 4 can be increased with almost no change in the hot water supply temperature, and the stability of the hot water supply system is improved.

  FIG. 2 is a graph comparing rise times until the set temperature is reached during operation in the internal circulation hot water supply system according to the present invention and the conventional hot water supply system. The conventional hot water supply system used here is common in that it has an internal circulation, but instead of the regulating valve 29 provided in the return passage 5 in the present invention of FIG. 1, a fixed orifice is used, and the present invention. It is the structure which does not have the opening degree suppression means 35 in.

  As shown in FIG. 2, in the internal circulation type hot water supply system according to the present invention, the temperature of hot water is promptly from the start of operation of the system as indicated by the solid line by appropriately suppressing the return flow rate by the regulating valve 29 (FIG. 1). Rises and reaches the set temperature with a short rise time. On the other hand, in the conventional hot water supply system, as shown by the broken line, the temperature rise from the start of the system operation is slow, and it takes a long time to reach the set temperature. Thus, in the conventional hot water supply system, by using the fixed orifice, the internal circulation flow rate through the return passage 5 → tank 4 → water supply passage 20 → heat exchanger 2 in FIG. The time for the hot water to reach the set temperature, that is, the rise time becomes longer. On the other hand, in the internal circulation hot water supply system according to the present invention, at the start of operation, the adjustment valve 29 provided in the return passage 5 in FIG. Since the circulation is in a state of little or zero as much as possible, hot water having a set temperature can be obtained with a short rise time.

  According to the present invention configured as described above, the opening degree of the adjustment valve 29 provided in the return passage 5 is reduced by the opening degree suppression means 35 until the hot water supply temperature reaches the set temperature at the start of operation. It is possible to obtain hot water at a set temperature on the user load side with a short rise time, and it has excellent responsiveness. When the temperature of the hot water detected at the start of operation reaches the set temperature, the opening degree of the regulating valve 29 is gradually opened by the opening degree suppressing means 35, so that the internal circulation flow rate can be reduced without changing the hot water supply temperature. Since it can be gradually increased, the stability of the hot water supply system is improved.

  In addition, as shown in FIG. 1, a hot water supply adjustment valve 26 and a check valve 27 located upstream thereof are provided in a hot water supply passage 25 for supplying hot water from the heat exchanger 2 to an external load, and a return passage is provided. Is branched from between the hot water supply adjustment valve 26 and the check valve 27, the hot water supply passage 25 between the hot water supply adjustment valve 26 and the check valve 27 is filled with hot water, and this hot water is filled with the check valve. Therefore, the remaining hot water without being supplied with hot water can be reliably returned to the tank 4.

  Furthermore, since the temperature setting means 36 for setting the set temperature by an input operation from the outside is provided, the user can input an arbitrary set temperature from the outside to the temperature setting means 36. Excellent in properties.

  As described above, the preferred embodiments have been described with reference to the drawings, but various additions, changes, or deletions can be made without departing from the spirit of the present invention. Therefore, such a thing is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Internal circulation type hot water supply system 2 ... Heat exchanger 3 ... Steam control valve 4 ... Tank 5 ... Return passage 26 ... Hot water supply adjustment valve 27 ... Check valve 29 ... Adjustment valve 30 ... Hot water temperature sensor 33 ... Controller 34 ... Temperature adjustment Means 35 ... Opening suppression means 36 ... Temperature setting means

Claims (3)

A heat exchanger that generates hot water by heat exchange between steam and cold water;
A steam control valve for adjusting the amount of steam supplied to the heat exchanger;
A tank for storing the cold water introduced into the heat exchanger;
A return passage for returning a part of the hot water from the heat exchanger to the tank;
An adjustment valve provided in the return passage for adjusting the opening of the passage;
A hot water temperature sensor for detecting the temperature of the hot water;
Temperature adjusting means for adjusting the opening of the steam control valve so that the hot water temperature detected by the hot water temperature sensor becomes a set temperature;
An internal circulation type hot water supply system comprising: an opening degree suppression means for reducing an opening degree of the regulating valve until a hot water temperature detected at the start of operation reaches a set temperature.   In the internal circulation hot water supply system according to claim 1, a hot water supply adjustment valve and a check valve located upstream thereof are provided in a hot water supply passage for supplying hot water from the heat exchanger to an external load, An internal circulation hot water supply system in which the return passage is branched from between the hot water supply adjustment valve and the check valve in the hot water supply passage.   The internal circulation type hot water supply system according to claim 1 or 2, further comprising temperature setting means for setting the set temperature by an external input operation.

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