JP7056246B2 - Heat pump steam generation system - Google Patents

Description

The present invention relates to a heat pump type steam generation system capable of easily preventing the operation of the heat pump from being stopped due to a high temperature of the heat source hot water while increasing the temperature responsiveness of the heat source hot water.

As one of the steam generators, there is a heat pump type steam generator using a heat pump device. The heat pump type steam generator recovers waste heat from waste hot water (hot water) such as factory wastewater and used cooling water to generate steam. That is, in the heat pump type steam generator, the evaporator of the heat pump device functions as an exhaust heat recovery device, the exhaust heat is recovered from the exhaust hot water to the refrigerant, and the recovered heat is used to collect the heated water in the condenser. Since steam is generated by heating, there is an advantage that running cost and CO ₂ emissions can be reduced as compared with a combustion system steam generator that generates steam by using boiler equipment or the like.

For example, Patent Document 1 discloses a configuration in which hot water as a heat source is stored in a heat source water tank (hot water tank) in a heat pump type steam generator and supplied from this hot water tank to an exhaust heat recovery device.

Japanese Unexamined Patent Publication No. 2013-210118

By the way, in the case of supplying heat source hot water from a heat source hot water tank to a plurality of heat pumps, or in a system configuration in which heat source hot water is also supplied to heat utilization equipment other than the heat pump, the demand for heat source hot water increases and the amount of water supplied increases. If it increases, the temperature of the heat source hot water may drop because the heating for the water supply may not be in time, so a highly responsive heating means is required.

When the temperature of the heat source hot water drops, the thermal efficiency of the heat pump deteriorates, while when the inside of the heat source hot water tank is overheated and the temperature of the heat source hot water supplied to the heat pump exceeds a predetermined temperature, for example, 90 ° C., the heat pump becomes hot. May cause an emergency stop.

The present invention has been made in view of the above, and it is possible to easily prevent the heat pump from stopping due to the high temperature of the heat source hot water while increasing the temperature response of the heat source hot water. The purpose is to provide a system.

In order to solve the above-mentioned problems and achieve the object, the heat pump type steam generation system according to the present invention recovers heat from the heat source hot water to the refrigerant by using the heat pump, and the recovered heat is converted from the refrigerant to the heated water. It is a heat pump type steam generation system that transfers steam to generate steam and supplies the generated steam to heat utilization equipment. Detects the temperature of the heating unit that heats to a temperature to make the heat source hot water, the evaporator supply line that supplies the heat source hot water to the evaporator of the heat pump to heat the refrigerant, and the temperature of the supply water in the heat source hot water tank. A temperature sensor is provided, and separately from the heating unit, the heating steam supply mechanism for supplying at least a part of the generated steam as heating steam to the heat source hot water tank is included, and the heating steam supply mechanism is of the heating steam. It has a heated steam valve that can control the supply to the heat source hot water tank, and when the temperature sensor detects a temperature exceeding the steam heating stop temperature set based on the predetermined temperature, the heated steam valve is closed and controlled. Then, the supply of the heated steam to the heat source hot water tank is stopped.

Further, in the heat pump type steam generation system according to the present invention, in the above invention, the heated steam supply mechanism has a steam discharge valve capable of discharging the heated steam to the outside air, and the temperature sensor reaches the predetermined temperature. When a temperature exceeding the steam discharge temperature set based on the above is detected, the steam discharge valve is opened to provide a switching valve control unit that controls to discharge the heated steam to the outside air.

Further, in the above invention, the heat pump type steam generation system according to the present invention further includes a heat pump output control unit that controls the output of the heat pump, and in the heat pump output control unit, the temperature sensor exceeds the steam discharge temperature. When the temperature is detected, the output of the heat pump is reduced as compared with the normal operation.

Further, the heat pump type steam generation system according to the present invention is characterized in that, in the above invention, the heat source hot water return line for returning at least a part of the heat source hot water discharged from the evaporator to the heat source hot water tank is provided. ..

Further, the heat pump type steam generation system according to the present invention is further provided with a heated water supply line capable of directly supplying the heat source hot water as the heated water to the condenser of the heat pump in the above invention. ..

According to the present invention, when the temperature sensor detects a temperature exceeding the steam heating stop temperature set based on a predetermined temperature, the heating steam valve is closed and controlled to stop the supply of the heating steam to the heat source hot water tank. Therefore, it is possible to easily prevent the operation of the heat pump from being stopped due to the increase in temperature of the heat source hot water while increasing the temperature responsiveness of the heat source hot water.

FIG. 1 is a diagram showing a configuration of a heat pump type steam generation system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a water level control processing procedure by the water level control unit shown in FIG. FIG. 3 is a diagram showing an example of the relationship between the water supply amount and the water level. FIG. 4 is a flowchart showing a temperature control processing procedure by the temperature control unit shown in FIG. FIG. 5 is a diagram showing an example of the relationship between the heat pump output and the heat source hot water temperature.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

<Overall configuration>
FIG. 1 is a diagram showing a configuration of a heat pump type steam generation system 10 according to an embodiment of the present invention. The heat pump type steam generation system 10 is a system that recovers heat from heat source hot water and uses the recovered heat to generate steam, and the generated steam is sent to an external heat utilization facility 100 such as a cleaning facility.

As shown in FIG. 1, the heat pump type steam generation system 10 includes a heat pump 20 supplied as a heat source for steam generation, a gas-liquid separator 30 used for steam generation, a heat source hot water tank 40 for storing heat source hot water, and a control unit 60. Have. The heat source hot water stored in the heat source hot water tank 40 is supplied as a heat source of the heat pump 20 via the evaporator supply line L3 and as a heat source of the heated water for steam generation via the heated water supply line L4. The control unit 60 controls the operation of the heat pump 20, controls the water level of the heat source hot water, controls the temperature of the heat source hot water, and the like.

The heat pump 20 dissipates and condenses the evaporator 21 that recovers heat from the heat source hot water to heat the refrigerant, the compressor 22 that compresses the refrigerant heated by the evaporator 21, and the refrigerant compressed by the compressor 22. This is a refrigerating cycle device in which the condenser 23 for making the condenser 23 and the throttle expander 24 for expanding the refrigerant output from the condenser 23 are sequentially connected in an annular shape by a refrigerant pipe to circulate the refrigerant.

The refrigerant compressed by the compressor 22 to a high temperature and high pressure is supplied from the heated water supply line L4 and the heated water supply pump P2 in the condenser 23, and circulates in the circulation line L5 via the gas-liquid separator 30. It exchanges heat with the water to be heated, is cooled, and condenses. The refrigerant output from the condenser 23 is throttled and expanded by the throttle expander 24 which is an electronic expansion valve, and in the evaporator 21, heat is absorbed from the heat source hot water supplied via the evaporator supply line L3 and the heat source hot water supply pump P1. Evaporates and returns to the compressor 22 again.

The gas-liquid separator 30 is composed of a cylindrical container along the vertical direction, and the container is supplied with heated water from a heated water supply line L4 connected to a circulation line L5 connected to a lower wall. Store water inside. The heated water of the heated water supply line L4 is the heat source hot water of the heat source hot water tank 40. The heated water may not be hot water from a heat source, but may be water from a water supply source such as a water pipe or a water tank (not shown).

A steam delivery line L6 that sends the generated steam to the external heat utilization equipment 100 side is connected to the upper end wall of the gas-liquid separator 30. The two-phase flow in which water and steam from the condenser 23 are mixed is introduced into the gas-liquid separator 30 from the circulation line L5 on the outlet side of the condenser 23, where the steam after the water is separated is released. It is sent to the steam delivery line L6.

The steam sent out to the steam delivery line L6 is compressed by the steam compressor P3 and boosted. The boosted steam is sent to the heat utilization equipment 100 side via the steam delivery line L7, and the surplus steam is sent to the switching valve V12 side by the relief valve V2. The switching valve V12 switches between supply to the heat source hot water tank 40 via the surplus steam line L8 and drainage of the surplus steam. The steam supplied from the steam delivery line L7 is, for example, 120 ° C.

Supply water (soft water) such as city water is supplied to the heat source hot water tank 40 via a water supply line L1 and a water supply valve V1 which are water supply units. In the heat source hot water tank 40, a heater 41 for heating the heat source hot water, a temperature sensor 52 for detecting the temperature of the heat source hot water, and a water level sensor 50 for detecting the water level of the heat source hot water are arranged. The heat source hot water is supplied to the evaporator 21 and the condenser 23, respectively, via the above-mentioned evaporator supply line L3 and heated water supply line L4.

The endothermic hot water supplied to the evaporator 21 is returned to the heat source hot water tank 40 via the heat source hot water return line L13. The heat source hot water supplied to the evaporator 21 and absorbed heat may be drained to the outside without returning to the heat source hot water tank 40. Further, as described above, the surplus steam is supplied to the heat source hot water tank 40 via the switching valve V12 and the surplus steam line L8.

An overflow discharge line L2 is connected to the upper part of the heat source hot water tank 40. The overflow discharge line L2 is a discharge line for preventing the overflow of the heat source hot water tank 40, and discharges the increased heat source hot water to the outside when the water level of the heat source hot water in the heat source hot water tank 40 rises above a predetermined level. It is a thing.

A heat pump 20, a heater 41, a water level sensor 50, a temperature sensor 52, a water supply valve V1, a switching valve V12, a heat source hot water supply pump P1, and a heated water supply pump P2 are connected to the control unit 60. The control unit 60 includes a water level control unit 61, a temperature control unit 62, a switching valve control unit 63, and a heat pump output control unit 64.

The water level control unit 61 controls the opening of the water supply valve V1 based on the water level detected by the water level sensor 50, and controls the amount of water supplied to the heat source hot water tank 40. The temperature control unit 62 controls the amount of electricity supplied to the heater 41 based on the temperature detected by the temperature sensor 52 to control the amount of heat to the heat source hot water. The temperature control unit 62 controls the heat source hot water to a predetermined temperature, for example, 80 ° C. The temperature of the supply water is less than 80 ° C.

When the temperature sensor 52 detects a temperature exceeding the steam heating stop temperature set based on the predetermined temperature, the switching valve control unit 63 stops the supply of the surplus steam to the heat source hot water tank 40 via the surplus steam line L8. Perform switching control. Further, when the temperature sensor 52 detects a temperature exceeding the steam discharge temperature set based on the predetermined temperature, the switching valve control unit 63 opens the steam discharge side of the switching valve V12 to discharge excess steam to the outside air. I do. As a result, the temperature of the heat source hot water is prevented from becoming high, and the operation of the heat pump 20 can be continued. When the switching valve control unit 63 detects a temperature exceeding the steam heating stop temperature set based on the predetermined temperature, the switching valve control unit 63 switches the switching valve V12 to send excess steam via a surplus steam line (not shown). It may be supplied to the heat utilization equipment 100 side. As a result, the surplus steam can be effectively used.

For example, during normal operation, the heat pump output control unit 64 operates under superheat control that adjusts the drive rotation speed of the compressor 22 and the opening degree of the throttle expander 24 so that the refrigerant in the compression stroke has a predetermined superheat level or higher. Will be done. This superheat degree control is executed based on the detection values (suction pressure and suction temperature, discharge pressure and discharge temperature) of a pressure sensor and a temperature sensor (not shown) provided on one or both of the suction side and the discharge side of the compressor 22, for example. Will be done. As will be described later, when the temperature sensor 52 detects a temperature exceeding the steam discharge temperature, the heat pump output control unit 64 reduces the output of the heat pump 20 as compared with the normal operation to suppress the discharge of excess steam. conduct.

The water level is controlled by giving priority to the water level control in the temperature control unit 62.

<Water level control process>
Next, the water level control processing procedure by the water level control unit 61 will be described with reference to the flowchart shown in FIG. As shown in FIG. 2, first, the water level control unit 61 sets a supply amount of 1.5 L / min as the initial water supply setting (step S101). After that, the current water level of the heat source hot water is acquired from the water level sensor 50 (step S102). After that, based on the relationship of the water supply amount with respect to the water level shown in FIG. 3, control for setting the water supply amount with respect to the acquired water level level is performed (step S103), and the process proceeds to step S104.

In step S104, it is determined whether or not there is an end instruction for the water level control process, and if there is no end instruction (steps S104, No), the process proceeds to step S102 to continue the above-mentioned process, and the end instruction is given. In the case (step S104, Yes), this process is terminated.

Regarding the relationship of the water supply amount with respect to the water level shown in FIG. 3, the water level is set to 2.5 L / min while the water level is between 20% and 90%, and the water level is increased between 90% and 95%. The water supply amount is set to 0 according to the above, and the supply amount is set to 0 when the water level level is between 95% and 100%. Regarding the relationship between the water supply amount and the water level shown in FIG. 3, the water supply amount is relatively large up to 90%, and the appropriate water level is between 90% and 95%. By performing such water level control, the water level can be quickly maintained between 90% and 95%.

When the water level becomes 20% or less, an abnormal process for urgently stopping the heat pump 20 is performed.

<Temperature control processing>
Next, the temperature control processing procedure by the temperature control unit 62 will be described with reference to the flowchart shown in FIG. As shown in FIG. 4, first, the temperature control unit 62 sets the heat source hot water temperature to 80 ° C. as the initial temperature setting (step S201). After that, the temperature control unit 62 determines whether or not the temperature (heat source hot water temperature) detected by the temperature sensor 52 is 80 ° C. or lower (step S202).

When the heat source hot water temperature is 80 ° C. or lower (step S202, Yes), the energization to the heater 41 is turned on (step S203), and the switching valve V12 is switched to the heat source hot water side (surplus steam line L8 side) (step). S204), the heat source hot water is heated using the surplus steam, and the process proceeds to step S207.

On the other hand, when the heat source hot water temperature is not 80 ° C. or lower (step S202, No), the energization to the heater 41 is turned off (step S205), the switching valve V12 is further switched to the steam discharge side (step S206), and the surplus steam. The process proceeds to step S207 so as not to supply the heat source to the hot water side. The temperature (80 ° C.) at this time is the heated steam stop temperature. As described above, the surplus steam may be supplied to the heat utilization equipment 100 side instead of the steam discharge side.

In step S207, the heat pump output control unit 64 is made to control the heat pump output based on the relationship of the heat pump output with respect to the heat source hot water temperature shown in FIG. 5, and the process proceeds to step S208.

In step S208, it is determined whether or not there is an end instruction for the temperature control process, and if there is no end instruction (steps S208, No), the process proceeds to step S202 to continue the above-mentioned process, and the end instruction is given. In the case (step S208, Yes), this process is terminated.

Regarding the relationship of the heat pump output with respect to the heat source hot water temperature shown in FIG. 5, the heat source hot water temperature is set to 81 ° C., the heat pump output is set to 100%, the heat source hot water temperature is between 81 ° C. and 86 ° C., and the heat source hot water temperature rises. , The heat pump output is reduced, and when the heat source hot water temperature is 86 ° C., the heat pump output is set to 50%. Further, when the heat source hot water temperature is 86 ° C. or higher, the heat pump output is set to be constant at 50%. By performing such heat pump output control, when the heat source hot water temperature exceeds the steam discharge temperature (81 ° C) set based on 80 ° C (predetermined temperature), the heat source hot water by the surplus steam that is always output is always output. It is possible to suppress the temperature rise of.

Both the switching control of the switching valve control unit 63 for the switching valve V12 and the output reduction control by the heat pump output control unit 64 may be performed, or only one of them may be controlled.

Further, the above-mentioned switching valve V12 is designed to switch the surplus steam between the heat source hot water side and the steam discharge side with one valve, but the present invention is not limited to this, and the surplus steam is replaced with the switching valve V12 to be the heat source hot water. It may be composed of two independent valves, a heated steam valve for supplying to the side and a steam discharge valve for allowing excess steam to be discharged to the outside air on the steam discharge side. As described above, the steam discharge valve may supply excess steam to the heat utilization equipment 100. Alternatively, a switching valve may be provided on the downstream side of the steam discharge valve to switch between discharging the outside air on the discharge side and supplying the heat to the heat utilization equipment 100 side. Further, the surplus steam (heated steam) supplied to the hot water side of the heat source via the switching valve V12 may be a part of the generated steam, and does not have to be all of the surplus steam.

In the present embodiment, the excess steam continues to heat the heat source hot water, and if there is no cooling means, the heat source hot water tends to exceed the predetermined temperature, and if the temperature exceeds the predetermined temperature, the heat pump 20 cannot be operated. Since the excess steam is exhausted and the generation of excess steam is reduced by the heat pump output control unit 64, the heat source hot water is less likely to exceed the predetermined temperature, and the heat pump 20 can be continuously operated.

Further, in the present embodiment, the switching valve V12 is switched based on the temperature detected by the temperature sensor 52 without using a flow meter or the like for measuring the flow rate of excess steam, so that the switching is performed with a simple configuration. Switching control of the valve V12 can be performed. The switching control of the switching valve V12 is based on the fact that when the temperature exceeds a predetermined temperature, it can be considered that excess steam is being supplied.

Further, in the present embodiment, the heat source hot water is supply water (soft water) such as tap water passed through a water softener or the like, and water with few impurities is used. You may use drainage.

Further, since the surplus steam is supplied to the heat source hot water tank 40, an energy saving effect can be obtained and the heating capacity of the heating means such as the heater 41 can be suppressed.

The heat source hot water supplied to the evaporator 21 is returned to the heat source hot water tank 40 after absorbing heat, so that an energy saving effect can be obtained.

Further, the heating of the heat source hot water is not limited to the heater 41, and other heating means may be used. For example, it may be heated by the amount of heat of waste heat wastewater such as factory wastewater via a heat exchanger.

Further, each configuration shown in the above-described embodiment is a schematic function, and does not necessarily have to be physically illustrated. That is, the form of distribution / integration of each device and component is not limited to the one shown in the figure, and all or part of them may be functionally or physically distributed / integrated in any unit according to various usage conditions. Can be configured.

10 Heat pump type steam generation system 20 Heat pump 21 Evaporator 22 Compressor 23 Condenser 24 Squeeze expander 30 Gas-liquid separator 40 Heat source Hot water tank 41 Heater 50 Water level sensor 52 Temperature sensor 60 Control unit 61 Water level control unit 62 Temperature control unit 63 Switching valve control unit 64 Heat pump output control unit 100 Heat utilization equipment L1 Water supply line L13 Heat source hot water return line L2 Overflow discharge line L3 Evaporator supply line L4 Heated water supply line L5 Circulation line L6, L7 Steam delivery line L8 Surplus steam line P1 Heat source Hot water supply pump P2 Heated water supply pump P3 Steam compressor V1 Water supply valve V12 Switching valve V2 Relief valve

Claims (4)

It is a heat pump type steam generation system that recovers heat from the heat source hot water to the refrigerant using a heat pump, transfers the recovered heat from the refrigerant to the heated water to generate steam, and supplies the generated steam to the heat utilization equipment. hand,
The water supply unit that supplies the supply water to the heat source hot water tank,
A heating unit that heats the supply water in the heat source hot water tank to a predetermined temperature to make the heat source hot water.
An evaporator supply line that supplies the heat source hot water to the evaporator of the heat pump to heat the refrigerant, and
A temperature sensor that detects the temperature of the supply water in the heat source hot water tank, and
Equipped with
In addition to the heating unit, it includes a heating steam supply mechanism that supplies at least a part of the generated steam as heating steam to the heat source hot water tank.
The heated steam supply mechanism has a heated steam valve capable of controlling the supply of the heated steam to the heat source hot water tank.
When the temperature sensor detects a temperature exceeding the steam heating stop temperature set based on the predetermined temperature, the heating steam valve is closed and controlled to stop the supply of the heating steam to the heat source hot water tank.
The heated steam supply mechanism has a steam discharge valve that allows the heated steam to be discharged to the outside air.
When the temperature sensor detects a temperature exceeding the steam discharge temperature set based on the predetermined temperature, the steam discharge valve is opened to provide a switching valve control unit that controls to discharge the heated steam to the outside air. A heat pump type steam generation system featuring. Further, the heat pump output control unit for controlling the output of the heat pump is further provided, and when the temperature sensor detects a temperature exceeding the steam discharge temperature, the heat pump output control unit reduces the output of the heat pump as compared with the normal operation. The heat pump type steam generation system according to claim 1 . The heat pump type steam generation system according to claim 1 or 2 , further comprising a heat source hot water return line for returning at least a part of the heat source hot water discharged from the evaporator to the heat source hot water tank. The heat pump type steam generation system according to any one of claims 1 to 3 , further comprising a heated water supply line capable of directly supplying the heat source hot water as the heated water to the condenser of the heat pump. ..

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