JP4896623B2 - Air conditioning system - Google Patents

Description

  The present invention relates to an air conditioning system capable of converting and recovering kinetic energy of heat source water returned from an air conditioning load in a building to a heat storage tank.

  Conventionally, as an air conditioning system for buildings, factories, etc., heat source water heated or cooled using inexpensive late-night electricity is stored in a heat storage tank, and the stored heat source water is stored during the daytime when air conditioning loads occur. A regenerative air conditioning system that circulates and supplies air conditioning to an air conditioner that is an air conditioning load is employed. In such an air conditioning system, the heat source water pumped up in the building is supplied to the air conditioning load and then returned to the heat storage tank below the building through the return pipe. In this case, in order to prevent the heat source water pumped up to the high floor of the building from falling at high speed in the return water pipe, a water fall prevention valve is provided in the return water pipe at a position close to the heat storage tank. In order to avoid negative pressure in the return water pipe, a surge tank is provided on the roof of the building.

  In such a heat storage type air conditioning system, for example, as shown in Patent Documents 1 to 3, the kinetic energy of heat source water returned from the air conditioning load to the heat storage tank is converted into electric power by a water wheel provided in the return water pipe. It is also known to be recovered. That is, Patent Documents 1 and 2 disclose an air conditioning system that uses the power collected by a water turbine as driving power for a pump. Further, Patent Document 3 discloses a system in which a branch pipe that branches from an upstream of a water fall prevention valve provided in a return water pipe to a heat storage tank and leads heat source water is provided, and an energy recovery device is attached in the middle of the branch pipe. ing.

Japanese Patent Application No. 2004-3437 Japanese Patent Application No. 2004-3414 Japanese Patent Application No. 2004-340446

  However, the dynamic pressure in the return water pipe that returns the heat source water to the heat storage tank is very high, and there is a valve structure such as a water fall prevention valve. Cavitation occurs below the vapor pressure corresponding to. Due to these synergistic effects, there is a case where severe erosion is caused at a relatively high frequency, and the water fall prevention valve is broken.

  An object of the present invention is to provide an air conditioning system that can flow heat source water returned to a heat storage tank without causing cavitation in the return water pipe, and efficiently convert potential energy of the heat source water into electric power and recover it. There is to do.

In order to solve this problem, according to the present invention, in an air conditioning system that circulates heat source water from a heat storage tank disposed below a building to an air conditioning load in the building, the heat source is supplied from the air conditioning load to the heat storage tank. The return pipe for returning water is provided with a bent portion for converting the flow of the heat source water falling from the air conditioning load in the horizontal direction and a horizontal portion for flowing the heat source water in the horizontal direction, and the kinetic energy of the heat source water is provided in the horizontal portion. A water turbine and a pressure regulating valve are sequentially arranged in the flow of the heat source water, the radius of curvature of the bent portion is 1.5 times or more the pipe diameter D of the return water pipe, and the water wheel is started from the start end of the horizontal portion. And a water head detector that detects the hydrostatic head of the heat source water applied to the water turbine, and the detected hydrostatic head is set to a control target value. that opening of the pressure regulating valve is controlled The symptom, the air conditioning system is provided.

  In this air conditioning system, the flow of the heat source water falling from the air conditioning load in the building is converted into a horizontal direction at a bent portion having a curvature radius of 1.5 times or more of the pipe diameter D of the return water pipe, Thereafter, the heat source water is supplied to the water turbine after flowing a distance of 6 times or more the pipe diameter D in the horizontal portion.

  In this air conditioning system, a nozzle portion for reducing the pipe diameter D may be provided upstream of the water wheel. Further, as the water wheel, a water wheel having a smaller rated capacity than the capacity selected by design calculation may be adopted. Further, a bypass pipe that bypasses the water wheel and returns the heat source water to the heat storage tank may be provided, and a flow rate adjusting valve may be provided in the bypass pipe. Moreover, you may provide the control apparatus which controls the said flow regulating valve based on the differential pressure | voltage of the upstream and downstream of the said water turbine, or the rotation speed of the said water turbine.

  According to the present invention, it is possible to prevent the occurrence of cavitation in the return water pipe, supply the heat source water without generating vortex flow to the water turbine, and efficiently recover the potential energy of the heat source water. become. In addition, by providing a nozzle part and a pump for reducing the pipe diameter D upstream of the water wheel, the speed of the heat source water can be increased and supplied to the water wheel. Also, if a bypass pipe is provided that bypasses the water turbine and returns the return water pipe to the heat storage tank, and the flow adjustment valve is provided in the bypass pipe, the maintenance performance of the water turbine is improved by appropriately controlling the flow adjustment valve. Will be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall view of an air conditioning system according to an embodiment of the present invention. FIG. 2 is an enlarged view of a main part of the air conditioning system. FIG. 3 is an explanatory diagram of the nozzle unit 21. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 1, a heat storage tank 1 is provided below a building (not shown) such as a building. The heat storage tank 1 stores heat source water a that is heated or cooled by using inexpensive late-night power by a heat source device such as a heat pump (not shown).

  From the heat storage tank 1, a pumping pump that pumps the heat source water a from the heat storage tank 1 to the air conditioner 2 and supplies the heat source water a to the air conditioner 2 that is an air conditioning load provided in the building. 5 and a check valve 6 for preventing the back flow of the heat source water a in the outgoing water pipe 3. Actually, the air conditioner 2 is arranged for each floor in the building, and a plurality of air conditioners 2 are appropriately provided on each floor according to the direction and the addition of air conditioning. And the heat source water a which came out of these several air conditioners 2 merges, and is returned to the thermal storage tank 1 through the return water pipe 10 as a main pipe.

  The return water pipe 10 that returns the heat source water a from the air conditioner 2 to the heat storage tank 1 is provided with a water turbine 11 that recovers the kinetic energy of the heat source water a flowing in the return water pipe 10. Although not shown, a surge tank for avoiding negative pressure in the return water pipe 10 is provided on the roof of the building.

  All of the return water pipes 10 are constituted by circular pipes having a pipe diameter D except for a nozzle portion 21 described later. Further, the return water pipe 10 is connected to a bypass pipe 12 that can bypass the water wheel 11 and flow the heat source water a. The bypass pipe 12 is provided with a flow rate adjustment valve 13. The flow rate adjusting valve 13 is a so-called normally closed valve, which is normally closed as will be described later. However, the flow rate adjusting valve 13 is appropriately opened and the opening degree is adjusted by a command from the control device.

  As shown in FIG. 2, a bent portion 10a for converting the flow of the heat source water a falling from the air conditioning load 2 in the horizontal direction and a horizontal portion 10b for flowing the heat source water a in the horizontal direction are provided in the downstream portion of the return water pipe 10. And the lower part 10c which makes the heat-source water a flow down to the thermal storage tank 1 is formed. The upstream end 12a of the bypass pipe 12 is branched and connected to the downstream side of the start end of the horizontal portion 10b (connection position between the bent portion 10a and the horizontal portion 10b). The downstream end of the bypass pipe 12 is joined and connected to the flow lower part 10c.

  The bent portion 10a has a curvature radius ρ that is 1.5 times or more of the pipe diameter D, and the heat source water a flowing down from the air conditioner 2 through the return pipe 10 flows through the bent portion 10a. The flow direction can be gradually changed to the horizontal direction. The radius of curvature ρ of the bent portion 10a is determined based on the center line of the bent portion 10a. For example, an elbow or bend which is a kind of piping component is used for the bent portion 10a. These elbows and bends are classified into 45 °, 90 °, and 180 ° depending on the bending angle, but if the flow direction of the heat source water a that has flowed vertically from the air conditioner 2 is converted to the horizontal direction, An elbow or bend with a bending angle of 90 ° may be used. The elbow and the bend include a short elbow, a long elbow, a short bend, and a long bend, respectively, depending on the curvature radius ρ. The radius of curvature ρ is about 1 times the pipe diameter D for short elbows, about 1.5 times the pipe diameter D for long elbows, about 4 times the pipe diameter D for short bends, and about the pipe diameter D for long bends. 5 times. Therefore, in the present invention, any one of a long elbow, a short bend, and a long bend may be used for the bent portion 10a.

  The distance L from the starting end of the horizontal portion 10b to the water wheel 11 is set to be 6 times or more the pipe diameter D. The pipe diameter D is defined by the inner diameter of the return water pipe 10. However, if the thickness is not taken into consideration, the outer diameter of the return water pipe 10 may be approximated.

  Further, the horizontal portion 10b of the return water pipe 10 has an on-off valve 20, a nozzle portion 21, a water wheel 11, a pressure in the order of the flow direction of the heat source water a on the downstream side of the branch extraction position of the upstream end 12a of the bypass pipe 12. An adjustment valve 22 and an on-off valve 23 are provided. The on-off valve 20 and the on-off valve 23 are normally open. For example, when the water turbine 11 is inspected or repaired, the on-off valve 20 and the on-off valve 23 are closed.

  As shown in FIGS. 3 and 4, the nozzle portion 21 has a pipe diameter D on the inlet side, but has a diameter d smaller than the pipe diameter D on the outlet side. For this reason, in the nozzle part 21, the flow rate of the heat source water a is gradually increased while flowing from the inlet side to the outlet side. As shown in FIG. 3, the inside of the nozzle portion 21 may have a shape in which the center height of the inner diameter is horizontal and the diameter is reduced, or as shown in FIG. The shape may be such that the center height descends downstream.

  The water turbine 11 incorporates an impeller that is rotated by the flow of the heat source water a, and the kinetic energy of the heat source water a is recovered by the water wheel 11. In addition, the connection of the water turbine 11 ensures a torque so that the flow of the heat source water a is in a normal direction with respect to the built-in impeller. Then, AC power is generated by the generator 25 using the kinetic energy recovered by the water turbine 11. A frequency converter 26 capable of arbitrarily converting the frequency of the generated AC power is connected to the generator 25, and the AC power inverter-converted to an appropriate frequency by the frequency converter 26 is used to convert the power distribution board 27. Via, it is supplied to various devices provided in the building.

  The generator 25 is not a dielectric generator but a synchronous AC generator. The dielectric generator cannot control the current of the exciting coil, and there is no place for the generated electric power, so it is necessary to link the grid to burn out. When the grid is linked, electric power companies are required to guarantee the voltage and frequency of power supplied to various devices. On the other hand, if it is a synchronous alternating current generator, the electric current sent through an exciting coil can be adjusted and a voltage can be controlled to be constant, and a system linkage becomes unnecessary. In this case, by limiting the target to lighting equipment or air conditioning equipment (motor power for air conditioning / ventilation, etc.) as equipment for supplying electric power, system linkage becomes unnecessary, and excessive capital investment can be prevented.

  The pressure adjustment valve 22 is a so-called normally open valve, and is normally in an open state as will be described later. However, the opening degree of the pressure adjustment valve 22 is appropriately adjusted by a command from the control device. It is like that.

  In the air conditioning system according to the embodiment of the present invention configured as described above, when the air conditioning operation is performed, the heat source water a stored in the heat storage tank 1 is pumped up and supplied to the air conditioner 2 by the operation of the pump 5. Then, cool or heat appropriately. Thus, the heat source water a that has consumed heat due to the air conditioning load in the building falls from the air conditioner 2 into the return water pipe 10 and is returned to the heat storage tank 1 below the building, at which time the heat source flowing in the return water pipe 10 The kinetic energy of the water a is recovered by the water turbine 11. Here, when the inside of the pipe is full of water upstream of the water turbine 11, it is preferable to ensure power generation efficiency. In this way, AC power is generated by the generator 25 by the recovered kinetic energy, and the AC power converted to an appropriate frequency by the frequency converter 26 is supplied to various devices in the building via the switchboard 27.

  In this case, the bent portion 10a provided in the return water pipe 10 has a curvature radius ρ that is 1.5 times or more of the pipe diameter D, and the distance L from the start end of the horizontal portion 10b to the water turbine 11 is the pipe diameter. Since it is set to be 6 times or more of D, the flow of the heat source water a falling from the air conditioner 2 in the return water pipe 10 is gently changed into a horizontal flow without causing cavitation or vortex flow. Thus, the potential energy of the heat source water a can be efficiently recovered as electric power. Moreover, damage to each valve 20, 22, 23 etc. provided in the return water pipe 10 can also be prevented. In addition, in the horizontal portion 10b, the static pressure can be increased as compared with the vertical piping, the risk of air mixing can be reduced, and energy can be recovered in a constantly full water state.

  Further, by providing the nozzle portion 21 for reducing the pipe diameter D to the diameter d upstream of the water turbine 11, the nozzle portion 21 can increase the speed of the heat source water a and supply it to the water turbine 11. Insufficient rotation speed can be avoided. In this case, a full water state can always be maintained on the upstream side of the water turbine 11.

  Next, the control device of the air conditioning system is configured as follows. First, the hydrostatic head H of the heat source water a applied to the water turbine 11 is detected by the water head detector 30. And the opening degree of the pressure control valve 22 is controlled by the proportional integration operation so that the detected hydrostatic head H becomes the control target value. In this case, the pressure control valve 22 adjusts the opening degree to the closed side by setting the maximum hydrostatic head or less as the control target value. As a result, the water wheel 11 and the pressure control valve 22 also function as a water fall prevention valve, and the inside of the return water pipe 10 is always full to prevent cavitation. In addition, since the water wheel 11 and the pressure control valve 22 also function as a conventional water fall prevention valve, the water fall prevention valve can be omitted. Since the pressure control valve 22 uses a normally open type that opens when no control signal current or no current is applied, it is possible to prevent the air conditioning system from functioning even when there is an abnormality.

  Further, in the horizontal portion 10 b of the return water pipe 10, the differential pressure of the heat source water a applied before and after the water turbine 11 and the pressure control valve 22 is detected by the differential pressure detector 31. Then, the flow rate adjustment valve 13 is controlled based on the detected differential pressure ΔP.

  That is, when the differential pressure ΔP is within the allowable range, the normally closed flow rate adjustment valve 13 remains closed as it is. For this reason, the heat source water a does not flow into the bypass pipe 12.

  On the other hand, when the differential pressure ΔP exceeds the allowable range, the opening degree of the flow regulating valve 13 is opened by proportional control. Thereby, a part of the heat source water a flowing in the return water pipe 10 flows to the bypass pipe 12, and the heat source water a flowing to the horizontal portion 10b is reduced, thereby preventing excessive water pressure from being applied to the water wheel 11 and the pressure control valve 22. can do. Thereby, generation | occurrence | production of a cavitation and a vortex flow can be avoided. In this case, the display lamp may be turned on by detecting that the differential pressure ΔP exceeds the allowable range.

  Further, when the rotational speed of the water turbine 11 is 1.5 times or more the rotational speed determined by the number of poles of the generator 25 (synchronous alternating current generator), for example, the frequency detection function incorporated in the generator 25 is used. The opening degree of the flow rate adjustment valve 13 may be proportionally controlled using the generator output as a control signal. In this case as well, a part of the heat source water a flowing in the return water pipe 10 flows to the bypass pipe 12, and the heat source water a flowing to the horizontal portion 10b is reduced, so that an abnormal rotation speed of the water turbine 11 can be avoided.

  Moreover, when the necessity of inspection, repair, etc. of the water wheel 11 or the pressure control valve 22 arises, the flow volume adjustment valve 13 is open | released and the on-off valve 20 and the on-off valve 23 provided in the horizontal part 10b are closed. As a result, the water turbine 11 and the pressure control valve 22 can be inspected and repaired without stopping the operation of the air conditioning system, and the maintainability and the like can be improved.

  As mentioned above, although an example of preferable embodiment of this invention was demonstrated, this invention is not limited to the form of illustration. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs. For example, although the example which provided the nozzle part 21 just before the water wheel 11 was shown, if the rotation speed shortage of the water wheel 11 does not generate | occur | produce, you may abbreviate | omit the nozzle part 21. In addition, when providing the nozzle part 21, it is preferable that ratio d / D of the diameter d of the exit side with respect to the diameter (piping diameter D) of an entrance side shall be 0.4 or less.

  Moreover, in order to make the rotation speed of the water turbine 11 faster, instead of providing the nozzle portion 21, a disadvantage of cost can be avoided by adopting a water turbine smaller than the standard as the water turbine 11. The turbine smaller than the standard adopted as the turbine 11 is a turbine having a rated capacity smaller than the capacity selected by design calculation. As this water wheel, for example, a general-purpose pump whose count is lowered by 1 can be used. Such a pump has a small torque, but the impeller is small, so that the rotational speed can be increased. On the upstream side of this pump, when the diameter of the pipe is reduced by means such as the nozzle portion 21 in accordance with the suction opening of the pump, the flow of the heat source water a becomes smooth, but the means such as the nozzle portion 21 is not necessarily provided on the pump suction side. There is no need to provide. Further, the bent portion 10a may be one 90 ° elbow, but may be constituted by using two 45 ° elbows.

  The present invention can be applied to an air conditioning system having a heat storage tank.

1 is an overall view of an air conditioning system according to an embodiment of the present invention. It is an enlarged view of the principal part of an air conditioning system. It is explanatory drawing of a nozzle part. It is explanatory drawing of a nozzle part.

Explanation of symbols

a Heat source water 1 Heat storage tank 2 Air conditioner 3 Outgoing pipe 5 Pumping pump 10 Return water pipe 10a Bending part 10b Horizontal part 10c Flowing part 11 Water wheel 12 Bypass pipe 13 Flow control valve (normally closed)
22 Pressure adjustment valve 25 Generator 30 Water head detector 31 Differential pressure detector

Claims (5)

In the air conditioning system that circulates heat source water from the heat storage tank located below the building to the air conditioning load in the building,
A return pipe that returns the heat source water from the air conditioning load to the heat storage tank is provided with a bent portion that horizontally converts the flow of the heat source water falling from the air conditioning load, and a horizontal portion that causes the heat source water to flow in the horizontal direction,
In the horizontal portion, a water wheel for collecting the kinetic energy of the heat source water and a pressure regulating valve are sequentially arranged in the flow of the heat source water,
The radius of curvature of the bent portion is 1.5 times or more the piping diameter D of the return water pipe,
The distance from the start end of the horizontal portion to the water wheel is at least 6 times the pipe diameter D of the return water pipe ,
An air conditioner comprising a water head detector for detecting a hydrostatic head of heat source water applied to the water turbine, and the opening of the pressure control valve is controlled so that the detected hydrostatic head becomes a control target value. system. The air conditioning system according to claim 1, wherein a nozzle portion for reducing the pipe diameter D is provided upstream of the water wheel. The air conditioning system according to claim 1, wherein a water turbine having a rated capacity smaller than a capacity selected by design calculation is adopted as the water wheel. The air conditioning system according to any one of claims 1 to 3, wherein a bypass pipe that bypasses the water turbine and returns heat source water to the heat storage tank is provided, and a flow rate adjusting valve is provided in the bypass pipe. 5. The air conditioning system according to claim 4, further comprising a control device that controls the flow rate adjusting valve based on a differential pressure between an upstream side and a downstream side of the water turbine or a rotation speed of the water turbine.

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