JP2023175589A - Check valve and solar heat utilization system - Google Patents

Abstract

To achieve a solar heat utilization system that integrates a heat collector that receives solar light to heat a fluid and a heat pump, in which a fluid in a supply pipe to the heat collector and a return pipe from the heat collector is all discharged when discharging the fluid in the supply pipe and the return pipe to prevent fluid from freezing; to develop, for the achievement of the solar heat utilization system, a check valve that is opened/closed with a very small differential pressure; and to achieve the cost reduction.SOLUTION: A check valve connects a pipe and a pipe and prevents a fluid that flows in the pipe from flowing back, where a check-valve that opens/closes a flow channel is connected with the pipes so that a valve body is movable in a check-valve body according to a differential pressure of the fluid and opens/closes the flow channel.SELECTED DRAWING: Figure 8

Description

The present invention provides a solar water heating system that uses solar heat to heat water, and in winter, in order to prevent the water in the collector from freezing, a drain valve is provided in the water pipe that supplies water to the collector. , relates to a solar heat utilization system in which the water in the heat collector and heat collection pipes is drained by opening the drain valve when the temperature reaches a low temperature where there is a risk of freezing.

Conventionally, a solar heat utilization system that heats water or a heat medium using solar heat has been disclosed (Patent Document 1). A solar heat utilization system uses a heat collector that collects solar heat and heats water or a heat medium flowing in a pipe. Water in the collector may freeze in cold conditions.

JP2011-47582 JP2016-85030

Patent Document 1 discloses an electric drain valve that drains water in a heat collector and piping in order to prevent water in the heat collector from freezing. This electric drain valve is installed at a low position in the system, and when the power to the drain valve is turned off, the drain valve opens and the water in the heat collector and piping is drained. However, since the technique described in Patent Document 1 relies only on gravity for drainage, there is a risk that water may remain in a part of the heat collector and piping.

Therefore, in Patent Document 2, in order to drain the water in the heat collector, residual water, etc. in the heat collector and piping is forcibly sucked in by a blower, and a gas-liquid separation tank is installed in front of the suction port of the blower. discloses a technology for draining water.

However, if a device is installed that forcibly sucks out residual water or the like in the heat collector using a blower, there is a problem in that the cost of the system increases. In addition, when draining the water from the heat collector to prevent it from freezing, there is still concern that if there is a power outage or the power breaker is tripped, the blower will not operate, leading to freezing and damage.

It is most desirable to have a system in which the water in the heat collector and piping can be completely drained when the drain valve is opened. In a system that relies solely on gravity for drainage, what are the possible causes of water remaining in some parts of the heat collector and piping? This means that the return piping that returns hot water from the heater to the hot water storage tank is constructed so that it maintains a downward slope toward the drain valve. This is a construction management issue rather than a technical issue. Another reason is that water must be drained from both the water supply pipe to the heat collector and the return pipe that returns hot water from the heat collector to the hot water storage tank, but from the perspective of cost reduction, the drain valve is Patent Document 1 discloses a method that allows water to drain from both drain pipes by providing only one pipe in the water supply pipe. The method is to install a check valve between the return pipe and the water supply pipe that allows water to flow only from the return pipe to the water supply pipe, thereby allowing water to be drained from the return pipe as well.

In this method, if the differential pressure for opening and closing the check valve provided between the return pipe and the water supply drain pipe is not sufficiently small, water may remain in the return pipe. A general check valve, as shown in cross section in FIG. 1, has a structure that is sealed with a spring or the like to ensure backflow prevention. Then, in order for water to flow in the permissible direction, the valve will not open unless water pressure is applied to overcome the spring. When draining to prevent freezing using gravity alone, the check valve must remain open even when there is no pressure in order for water to drain through the check valve without leaving any water in the piping. Check valves that operate at very low differential pressures include hinge-type valves as shown in Figure 2 and ball-type valves as shown in Figure 3, but even these require some pressure to open. The present invention provides a low-cost direct water heat collection type solar water heating system by devising a check valve that opens with a pressure difference small enough to completely drain the water in the return pipe and closes reliably in the opposite direction. The aim is to realize this and promote the use of solar heat.

Even with a check valve as shown in FIG. 3 without a spring as shown in FIG. 1, water must flow upwards, so water cannot be completely drained through this check valve by gravity alone. When the check valve in Fig. 3 is turned sideways as shown in Fig. 4 (B), the ball will fall down and open the valve as shown in Fig. 4 (2) even if there is no pressure, but the It is possible that the valve will not close even when the water flows in one direction, and the valve will not function as a check valve. As shown in FIGS. 5(A) and 5(B), if the ball guide rail 4 is provided so that the ball rolls horizontally from the closed state to open the valve, the valve can be opened and closed with a very small differential pressure. This means that the water in the pipes can be drained only by the action of gravity.

According to one embodiment of the present invention, it is possible to provide a check valve that opens and closes with a small pressure difference. In addition, this system prevents the water in the collector tubes of the collector that uses solar heat to heat water from freezing and damage the collector, making it a low-cost solar heat utilization system with good heat collection performance. The purpose is to provide

Cross-sectional view of a normal check valve equipped with a spring to completely stop reverse flow. Cross-sectional view of a conventional hinge-type check valve that can be used horizontally. Cross-sectional view of a conventional ball-type check valve that can be opened and closed with very low differential pressure. (A) An axial view of an explanatory diagram illustrating that stable operation cannot be expected if the check valve of FIG. 3 is used sideways. (B) A vertical cross-sectional view of the check valve in FIG. 4(A). (A) An axial view of the ball type check valve with a guide rail that can be opened and closed with a low differential pressure and used horizontally according to the present invention. (B) A cross-sectional view of the ball type check valve with a guide rail, which is used horizontally and can be opened and closed with a low differential pressure, as shown in FIG. 5(A) of the present invention. FIG. 1 is an axial view and a sectional view of a check valve according to an embodiment of the present invention. FIG. 7 is an axial view and a sectional view of a check valve according to another embodiment of the present invention. FIG. 1 is a diagram of a solar hot water supply system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solar hot water supply system according to an embodiment of the present invention and a check valve that operates at a low differential pressure that makes it possible to reduce the cost and improve the performance of the system will be specifically described with reference to the drawings.

FIG. 8 shows a system diagram of a solar hot water supply system according to one embodiment of the present invention. The solar hot water supply system of this embodiment includes a solar collector 200, a heat pump water heater 400, and a hot water storage tank unit 300 of the heat pump water heater. Hot water heated by a heat pump water heater 400 is poured into the hot water storage tank unit 300 from the upper part of the tank 310, and the hot water is accumulated in a layer without being mixed with the water accumulated at the lower part of the tank. Also, water is sent to the solar collector from the lower part of the tank 310 through the electromagnetic valve 312, through the water supply pipe 211 by the pump 215, becomes hot water in the solar collector, passes through the return pipe 212, and is reversed. Through the stop valve 314, the flow rate of the pump 215 is controlled so that the hot water accumulates in layers without being stirred with the water accumulated in the lower part of the tank, similar to when hot water is boiled from the upper part of the tank 310 with a heat pump.

A temperature sensor (not shown) is attached to the upper part of the heat collecting plate of the heat collector 200, and when the heat collecting plate temperature reaches a predetermined temperature or higher, for example, 45° C. or higher, the electromagnetic valve 312 opens and the pump 215 starts rotating. When the temperature of the heat collecting plate becomes below a predetermined temperature, for example below 45° C., the pump 215 is stopped and the solenoid valve 312 is also closed.

The flow rate control method of the pump is based on the temperature of the temperature sensor (not shown) installed on the top of the heat collecting plate of the heat collector 200, and the amount of circulating water to the heat collector measured by a flow meter 216. This is done by controlling the pump rotation speed so that the flow rate becomes a predetermined flow rate.

In addition to controlling the flow rate of the pump by the temperature of the heat collecting plate, a sensor is installed to measure the solar radiation intensity entering the heat collector, and the flow rate of the pump 215 is controlled based on the solar radiation intensity. It is also possible to control the temperature of hot water returned to the boiler so that it does not fall below a predetermined temperature.

The relationship between the heat collecting plate temperature and the amount of circulating water is controlled to maintain a predetermined functional relationship. As a result, the temperature of the hot water poured from the heat collector to the upper part of the tank 310 is controlled so as not to fall below a predetermined temperature, for example, 45°C, and the temperature stratification of the hot water and water in the tank 310 is It is maintained.

When boiling water using solar heat in this way, it can be operated under almost the same conditions as when boiling water using a heat pump. Therefore, the hot water storage tank of a mass-produced heat pump water heater is equipped with a T-joint for the water supply port to the heat collector and a T-joint for receiving hot water returned from the heat collector, and a diagram for opening and closing these joints is provided. By installing one solenoid valve shown at 312 in Figure 8 and two check valves shown at 313 and 314, it is possible to create a solar water heating system integrated with a heat pump water heater.

The solenoid valve indicated by 312 in Fig. 8 is used to prevent freezing, so when the drain valve 218 in Fig. 8 is opened to drain water from the heat collector and the pipes leading to the heat collector, the water in the hot water tank is not drained. It is intended to do so. Also, the check valve 314 in FIG. 8 has the same function as the electromagnetic valve 312, that is, it is a necessary valve to prevent the hot water in the tank 310 from flowing backward and being drained during antifreeze drainage. When heat collection is started after antifreeze drainage is performed, the check valve 313 receives a heat collection start signal because the return pipe 212 in FIG. 8 is filled with air and no water. When it comes out, the solenoid valve 312 opens, and the water from the bottom of the tank passes through the solenoid valve, passes through the flow meter 216 and the pump, and is pushed up by the water pressure in the tank 310 to the collector. The air in the collector is then discharged via the air discharge/intake valve 210 of FIG.

On the other hand, water is pushed up into the return pipe 212 in FIG. 8 through the check valve 313 by the water pressure in the tank 310, and the air in the return pipe 212 is discharged through the air discharge/intake valve 210 in FIG. When the inside of the heat collector is filled with water, the flow of water stops, which indicates that the flow rate of the flow meter shown at 216 in FIG. 8 has become 0, so the heat collection pump 216 in FIG. 8 starts rotating. . Then, due to the water pressure generated by the pump, the water pressure on the upper side of the check valve 313 in FIG. The hot water returning from the tank 310 pushes open the check valve 314 and enters the tank from the top of the tank 310.

In the solar water heating systems that have been used in Japan in recent years, the antifreeze heat collection method is commonly used, as it is technically extremely difficult to completely prevent water from freezing in the heat collector, and it is not necessarily cost-reducing. It has become However, the antifreeze heat collection method requires heat exchange from the antifreeze to water, and it is difficult to easily connect a solar heat collection system to a mass-produced heat pump hot water supply system as shown in FIG. Therefore, there is currently no commercially available integrated system that combines an antifreeze fluid heat collection type solar hot water supply system and a mass-produced heat pump water heater.

If the temperature of the temperature sensor of the heat collecting plate is close to the freezing temperature of water, 0°C, for example, below 3°C, the water inside the heat collecting plate may freeze and the heat collecting plate may be damaged. 218 is opened, and the water in the collector is drained through the water pipe 211 and out of the drain valve 218. In order to drain the water in the collector, an air discharge/intake valve 210 is connected to the top of the collector, from which air flows into the collector, is replaced with water, and is discharged. be done. The water in the hot water return line 212 from the collector pushes open the check valve 217 (the check valve of this patent application) and is drained through the drain valve 218. In order for the water in the return pipe 212 to completely drain out, the check valve 217 (the check valve of this patent application) must be opened even with extremely low water pressure, otherwise water may remain in the return pipe 212. occurs.

The above-mentioned drain valve 218 cannot completely prevent freezing accidents if it does not operate if the power is turned off or there is a power outage when it is necessary to carry out anti-freezing drainage. A spring-return electric valve is used that opens the valve with the force of a spring when the valve is turned off.

It is also possible to use another spring return electric valve without providing the check valve 217 (the check valve of this patent application) for draining the water in the return pipe 212, but from the viewpoint of cost, a check valve is preferable. is significantly cheaper than spring return electric valves. Conventionally used check valves shown in FIGS. 1, 2, and 3 require a certain amount of water pressure to open the check valve, and the water in the return pipe 212 cannot be completely drained using these check valves. There is a fear.

If the check valve 217 (the check valve of this patent application), which opens with extremely low water pressure and closes reliably with low reverse water pressure as described above, is installed as shown in FIG. 8, the water in the return pipe 212 in FIG. It is thought that it will come out completely. 5(A), (B) FIGS. 6 and 7 show an embodiment of the check valve of the present invention that operates with a low differential pressure.

5(A) and 5(B) show a horizontally placed type ball type check valve according to an embodiment of the present invention, FIG. 5(A) is a view seen from the axial direction, and FIG. ) is a cross-sectional view taken along line AA in FIG. 5(A). 2 is a Teflon ball, and when the Teflon ball is in contact with the O-ring 3 as shown in FIG. 5(B), the waterway is blocked in the direction from the waterway 5 to 6. The Teflon ball can roll on the guide rail 4 and move from side to side in FIG. 5(B).

Figure 6 shows the ball guide in a structure where the water inlet 6 and outlet 5 are bent at 90 degrees, whereas the water inlet 6 and outlet 5 are straight in Figure 5(A). It is a diagram showing in an easy-to-understand manner the specific structure of the rail 4. FIG. 6(A) is a cross-sectional view taken along line BB in FIG. 6(B), and FIG. 6(B) is a cross-sectional view taken along line A-A' in FIG. 6(A). A structure in which the guide rail 4 is attached to the lower lid 7 in FIG. 6(B) is shown.

FIG. 7 shows another embodiment of the check valve that operates with low differential pressure according to the present invention, in which there is no guide rail as in FIGS. 5 and 6, and there is no guide rail as shown in FIGS. are shifted in the vertical direction, and when the Teflon ball 2 rolls to the right in the water channel 5 in FIG. 7(B), it just hits the O-ring 3 and closes the water channel.

When actually installing the check valves shown in FIGS. 5 to 7, the Teflon ball 2 is installed so that it can move as horizontally as possible because it operates with a low differential pressure. Specifically, as shown in FIG. 5(A), if the check valve has a polygonal cross-sectional shape, and at least one side of the check valve is parallel to the guide rail 4, it becomes easy to set the levelness and arrange the check valve.

In addition, in order to connect the check valves shown in FIGS. 5 to 7 to piping, connecting joints are attached to the outlet side flow path 5 and the inlet side flow path 6 of the check valve to connect the pipes. Although not shown in the figure, there is also a structure that has nuts rotatably supported at the outlet and inlet of the check valve, and is butt-joined to the male thread on the outer surface of the tip of the pipe to be connected via a packing. It is possible.

The solar hot water supply system of the present embodiment shown in FIG. a hot water storage unit 300 for storing hot water; a heat collection pump 215 for supplying water to the heat collector 200; a water pipe 211 for supplying water from the hot water storage unit 300 to the heat collector 200; a return pipe 212 for discharging water, and a return pipe drainage check valve 217 (the check valve of this patent application) that allows water to flow only from the return pipe 212 to the water pipe 211, and for discharging water from the water pipe 211. and an air discharge/intake valve 210 for introducing air into the heat collector 200 or discharging gas from the heat collector 200. Therefore, the solar heat utilization system of this embodiment can also utilize various functions provided in a heat pump water heater, such as a bathtub hot water filling function, for hot water heated by solar heat. Heat pump water heaters can also be used as a backup heat source on rainy days when hot water cannot be heated using solar heat, or on cloudy days when there is a shortage of hot water using solar heat. A combination system of a direct water heat collection system that has good heat collection performance and can be used at a low cost, and a mass-produced heat pump water heater that can be supplied at a low price will be provided at a low cost.
It goes without saying that the solar hot water supply system of this patent application can be applied to heat media other than water.

Although various embodiments of the present invention have been described, the present invention is not limited only to these embodiments, and embodiments configured by appropriately combining the configurations of each embodiment are also within the scope of the present invention. It is something.

1... Check valve body 2... Check valve ball 3... O-ring 4... Ball guide rail 5... Check valve water outlet 6... Check valve water inlet 7... Lid with ball guide rail attached 8... of 7 Attach the lid to the check valve body Screw 11... Lid for assembly of swing type check valve 12... Swing disc 13 of swing type check valve... Hinge 14 of swing disc... Seat 100 of swing disc... Spring closing type check Valve 111...Water inlet 112 of check valve 100...Water outlet 113 of check valve 100...Water passage 120 of check valve 100...Disk 130 of check valve 100...Valve element 131 of check valve 100... Valve stem 140 of check valve 100... Disk spring 150 of check valve 100... Valve stem guide 200 of check valve 100... Heat collector 210... Air discharge/intake valve 211... Water pipe 212 to the heat collector... Collection Return pipe 215 from the heater... Heat collecting pump 216... Flow rate sensor 217... Check valve for drainage (check valve of this patent application)
218... Drain valve 300... Heat pump water heater hot water storage unit 310... Hot water storage tank 311... Pressure reducing valve 312... Pressure reducing valve 313... Check valve 314... Check valve 315... Mixing valve 316... Heat pump water heating pump 400... Heat pump water heater

Claims (9)

A check valve that connects pipes and prevents backflow of fluid flowing in the pipes,
a valve body that opens and closes the fluid flow path;
a guide that supports the valve body and guides the valve body to engage with the inlet of the check valve body;
The valve body is characterized in that the piping is connected to the piping so that the valve body freely moves on the guide according to the differential pressure of the fluid and opens and closes the flow path. A check valve that connects pipes and prevents backflow of fluid flowing in the pipes,
a valve body that opens and closes the fluid flow path;
a check valve body eccentric with respect to the outlet of the check valve so that the valve body fits at the inlet of the check valve;
The valve body is characterized in that the piping is connected to the piping so that the valve body freely moves within the check valve body according to the differential pressure of the fluid and opens and closes the flow path. 3. The check valve according to claim 1, wherein the pipes are connected so that the valve body moves horizontally. 4. The check valve according to claim 1, wherein the valve body is spherical, and a fitting portion into which the valve body fits is provided with a packing. The check valve according to claim 4, wherein the packing is a sheet-shaped or ring-shaped packing. The check valve according to any one of claims 1 to 5, characterized in that the check valve has a reference surface for setting horizontality so that the valve body can operate at a low differential pressure. The check valve according to claim 1, wherein a connecting joint is attached to an inlet and an outlet of the check valve to connect the pipes. A solar heat utilization system that integrates a heat pump and a collector that receives sunlight and heats fluid,
a tank for storing fluid circulating between the heat collector and the heat pump;
Control for supplying low-temperature fluid from the bottom of the tank to the heat collector and the heat pump through supply piping, and controlling the fluid heated by the heat collector and the heat pump to return to the top of the tank through return piping. unit and
The check valve according to any one of claims 1 to 5, which is interposed in a pipe connecting the supply pipe and the return pipe and prevents flow from the supply pipe to the return pipe;
an electric valve connected to a pipe branched from the supply pipe;
an air intake/exhaust valve disposed above the heat collector for sucking or discharging air into the heat collector;
When discharging the fluid in the supply pipe to the heat collector and the return pipe from the heat collector in order to prevent the fluid from freezing, the control unit opens the air intake/discharge valve and also opens the electric valve. , a solar heat utilization system characterized in that all fluids in the supply piping and the return piping are discharged. The solar heat utilization system according to claim 8, wherein the fluid is water.

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