JP5845590B2 - Heat pump steam generator - Google Patents

Description

  The present invention relates to a heat pump type steam generator that recovers exhaust heat from factory wastewater and generates steam.

Conventionally, a heat pump circulation path is provided in an air conditioner, a refrigerator, or the like. In recent years, a heat pump circulation path is also used in the steam generation apparatus. The heat pump steam generator recovers exhaust heat such as factory wastewater and generates steam, which has lower running costs and reduced CO ₂ emissions compared to combustion steam generators. There is.

  In Patent Document 1, the other end of the refrigerant pipe having one end connected to the discharge side of the compressor is connected to the compressor via a steam generating heat exchanger, a hot water generating heat exchanger, an expansion valve, and a heat recovery unit. The refrigerant circuit connected to the suction side of the heat recovery unit recovers heat from the external heat source in the heat recovery unit, generates steam in the heat generation heat exchanger, and generates hot water in the heat generation heat exchanger A configured heat pump steam / hot water generator is disclosed.

  In the heat pump circulation path, the compressor compresses the medium (hereinafter also referred to as “heat pump medium”) into high-temperature superheated steam. However, if liquid is mixed in the compressor, liquid compression may occur and the compressor may be damaged. There is. For this reason, it is required to prevent liquid from entering the compressor. In Patent Document 1, the temperature of the compressor inlet is raised by reducing the flow rate of the heat pump medium by restricting the expansion valve, thereby suppressing the mixing of liquid into the compressor. However, this method has a problem in that when the flow rate of the heat pump medium is reduced, the amount of exchange heat in the exhaust heat recovery unit, the medium condenser, and the medium cooler is reduced, so that the ability as a heat pump is reduced.

  As another means of raising the compressor inlet temperature, a method of increasing the performance of the exhaust heat recovery device is conceivable. However, in this case, there is a problem that the exhaust heat recovery device is enlarged and the cost is increased. It was.

  Further, as another means, there is a method of raising the temperature from the outside with a heater or the like, but in this case, energy is required for heating the heater, which causes a problem that the energy efficiency of the entire apparatus is lowered. .

On the other hand, Patent Document 2 discloses a compressor that compresses a refrigerant, a radiator that radiates heat of the refrigerant compressed by the compressor, an expansion mechanism that depressurizes the refrigerant radiated in the radiator, and the expansion mechanism. is configured by an evaporator for evaporating the decompressed refrigerant is connected, molecular _formula: C ₃ H m _{F n} (where, m = 1~5, n = 1~5 and,, m + n = 6) And a refrigerant circuit filled with a single refrigerant composed of a refrigerant having one double bond in the molecular structure or a mixed refrigerant containing the refrigerant, and a radiator circuit. A refrigeration apparatus including a first internal heat exchanger that heats a refrigerant sent from an evaporator to a compressor by a refrigerant sent from the evaporator to the expansion mechanism is disclosed.

  According to the refrigeration apparatus of Patent Document 2, the first internal heat exchanger uses the relatively high-temperature refrigerant sent from the radiator to the expansion mechanism to heat the refrigerant sent from the evaporator to the compressor and compress it. Since the refrigerant sucked into the machine is prevented from becoming wet (that is, the refrigerant sucked into the compressor is overheated), the compressor is less likely to cause liquid compression. It is supposed to be possible.

JP 2007-232357 A JP 2009-222348 A

  Patent Document 2 is intended for a refrigeration apparatus, and a temperature taken out from a heat pump is lower than that of a steam generation apparatus. For this reason, what has a different characteristic from the heat pump medium of a freezing apparatus and the heat pump medium of a heat pump type steam generation apparatus is used.

Since it is necessary to take out a larger amount of heat as a heat pump medium of the heat pump type steam generator, it is necessary to use one having a high critical temperature. 1,1,1,3,3-pentafluoropropane (CHF ₂ CH ₂ CF ₃ (hereinafter referred to as R245fa), propane and the like are used. Also in patent document 1, R245fa is used as a heat pump medium.

  However, as shown in FIG. 3, the R245fa PH diagram shows that in the superheated steam region, the slope of the isentropic line is larger than the slope of the saturated steam line. There was a possibility of condensation from the vapor region to the gas-liquid region. Also in pentane, as shown in the PH diagram of FIG. 4, since the slope of the isentropic line is larger than the slope of the saturated steam line in the superheated steam region, the heat pump medium is used when the pressure is increased by the compressor. However, there was a possibility that it would be condensed from the superheated steam region to the gas-liquid region.

  Accordingly, an object of the present invention is to provide a heat pump type steam generator capable of suppressing the condensation of the heat pump medium in the compressor and stably taking out the steam over a long period of time.

The heat pump steam generator of the present invention is
An exhaust heat recovery unit that recovers heat from an external heat source to heat the medium, a compressor that compresses the medium that has passed through the exhaust heat recovery unit, and transfers the heat of the medium compressed by the compressor to the water to be heated. A heat pump circulation path having a medium condenser that generates a gas-liquid two-phase flow of hot water and steam, and an expander that depressurizes the medium that has passed through the medium condenser to lower the temperature;
A water supply path for introducing supply water to the medium condenser;
A gas-liquid separator that separates the gas-liquid two-phase flow of hot water and steam generated by the medium condenser into water vapor and water;
A vapor extraction path provided in a gas phase portion of the gas-liquid separator;
A heat pump type steam generator comprising a water circulation path connecting the liquid phase part of the gas-liquid separator and the water supply path,
In the superheated steam region of the PH diagram, the medium is a medium whose isentropic line has a larger slope than the saturated steam line and has a critical temperature of 150 ° C. or higher.
In the heat pump circulation path, heat exchange is performed between the medium of the wet steam from the medium condenser toward the expander and the medium of the wet steam from the exhaust heat recovery unit toward the compressor, and is introduced into the compressor. An internal heat exchanger for heating the medium to be heated is disposed, and the medium that has passed through the medium condenser becomes a supercooled liquid in the internal heat exchanger, is introduced into the expander, and passes through the exhaust heat recovery unit The obtained medium becomes superheated steam in the internal heat exchanger and is introduced into the compressor.

In the heat pump steam generating apparatus of the present invention, the medium is n-pentane (C ₅ H ₁₂ ), 1,1,1,3,3-pentafluoropropane (CHF ₂ CH ₂ CF ₃ ), 1,1, It is preferably one selected from 1,2,2,3,3-heptafluoro-3-methoxypropane (C ₃ F ₇ OCH ₃ ).

  The internal heat exchanger of the heat pump steam generator according to the present invention is a temperature at which the medium can be heated to the target temperature without condensing when the medium is compressed by the compressor and heated to the target temperature. Until the medium introduced into the compressor is heated.

  The heat pump type steam generating apparatus of the present invention preheats the supply water toward the medium condenser by exchanging heat between the medium from the internal heat exchanger toward the expander and the supply water toward the medium condenser. A medium cooler is preferably arranged.

  In the superheated steam region of the PH diagram, media with a greater isentropic slope than saturated steam may be condensed during compression if introduced into the compressor without being sufficiently heated. However, the heat pump steam generator of the present invention is introduced into the compressor by exchanging heat between the medium from the medium condenser to the expander and the medium from the exhaust heat recovery device to the compressor in the heat pump circulation path. By disposing the internal heat exchanger that heats the medium to be heated, the medium introduced into the compressor is heated, and condensation of the medium inside the compressor can be prevented. For this reason, damage to the compressor can be suppressed and steam can be taken out stably over a long period of time.

It is a schematic structure figure of a 1st embodiment of a heat pump type steam generating device of the present invention. It is a schematic block diagram of 2nd Embodiment of the heat pump type steam generation apparatus of this invention. It is a PH diagram of R245fa. It is a PH diagram of pentane.

  FIG. 1 is a schematic diagram of a first embodiment of a heat pump steam generator to which the present invention is applied.

  As shown in FIG. 1, in this heat pump type steam generator, a pipe L1 extending from the outlet side of the exhaust heat recovery unit 1 includes a low temperature medium part of an internal heat exchanger 10, a compressor 2, a medium condenser 3, A heat pump circulation path 20 connected to the inlet side of the exhaust heat recovery unit 1 is provided via the high-temperature medium part of the heat exchanger 10 and the expander 5 in this order.

  In the heat pump circulation path 20, a medium (hereinafter referred to as a heat pump medium) circulates and circulates, and a heat medium (in this embodiment, waste water is used as a heat medium sent from an external heat source via the heat pump medium. The heat of the heat pump medium is transferred to the supply water sent from the water supply source to generate steam.

As the heat pump medium, a medium in which the slope of the isentropic line is larger than the slope of the saturated vapor line in the superheated steam region of the PH diagram is used. _{Preferably, R245fa (CHF 2 CH 2 CF} 3), n- pentane _{(C 5} H 12), 1,1,1,2,2,3,3- heptafluoro-3-methoxypropane _{(C 3} F 7 OCH ₃ , 3M company product name: “HFE-7000”). These are preferably used because they have a critical temperature of 150 ° C. or higher, a low global warming potential, and a low ozone depletion potential.

  A pipe L <b> 2 extending from an external heat source and through which the exhaust hot water flows is connected to the outside of the system via the exhaust heat recovery device 1.

  A pipe L3 extending from the water supply source and through which the supply water circulates is connected to the gas phase portion of the gas-liquid separator 7 via a water supply pump (not shown) and the medium condenser 3 in this order.

  The gas-liquid separator 7 is provided with a pipe L4 in the gas phase portion with an on-off valve V1 for taking out the vapor. In the liquid phase part, a pipe L5 provided with an on-off valve V2 extending to a drainage system outside the system and a pipe L6 connected to the medium condenser 3 are provided.

  Next, the operation at the time of steady operation of the heat pump type steam generating apparatus of the present invention will be described along the flow of heat, taking the case of using R245fa as a heat pump medium as an example.

(Waste water)
Waste hot water (70 ° C. in this embodiment) sent from an external heat source such as a factory drainage system flows through the pipe L2 and passes through the exhaust heat recovery device 1 as waste water (60 ° C. in this embodiment). Sent.
In the exhaust heat recovery device 1, the heat of the exhaust hot water is transferred to the heat pump medium flowing through the pipe L1 to heat the heat pump medium.

(Heat pump medium)
The heat pump medium heated in the exhaust heat recovery device 1 by heat exchange with the exhaust hot water ( wet steam at 60 ° C. in this embodiment) is sent to the low temperature medium portion of the internal heat exchanger 10. Then, it is heated by heat exchange with the heat pump medium (in this embodiment, 130 ° C. wet steam ) that has passed through the medium condenser 3 and sent to the high-temperature medium section of the internal heat exchanger 10, and is sent to the compressor 2. . In the internal heat exchanger 10, when the heat pump medium is compressed by the compressor 2 and heated to the target temperature, it is preferable to heat the heat pump medium until the temperature reaches the target temperature without condensing. That is, in this embodiment, it is preferable to carry out until the heat pump medium becomes superheated steam of 70 ° C. or higher.

  In the compressor 2, the heat pump medium (70 ° C. superheated steam in this embodiment) heated by the internal heat exchanger 10 is compressed to a predetermined pressure to obtain a high-temperature high-pressure medium (130 ° C. superheated steam in this embodiment) and To do. This high-temperature and high-pressure medium passes through the medium condenser 3 and is used for heat exchange with the supply water flowing through the pipe L3.

  In the medium condenser 3, the heat of the high-temperature and high-pressure medium (heat pump medium) is transferred to the heated water flowing through the pipe L3 to generate a gas-liquid two-phase flow of hot water and steam.

  The heat pump medium that has passed through the medium condenser 3 is sent to the high-temperature medium part of the internal heat exchanger 10 and, as described above, heat exchange with the heat pump medium that is sent to the low-temperature medium part of the internal heat exchanger 10 results in internal heat. The heat pump medium flowing through the low temperature medium part of the exchanger 10 is heated. Then, the heat pump medium (the supercooled liquid at 120 ° C. in this embodiment) that has passed through the high-temperature medium portion of the internal heat exchanger 10 is expanded to a predetermined pressure by the expander 5 and reintroduced into the exhaust heat recovery unit 1. And used for the heat recovery of the exhaust hot water flowing through the pipe L2.

(Supply water)
The supply water (25 ° C. in this embodiment) supplied from a water supply source by a water supply pump (not shown) has a mass flow Q1 of the supply water discharged from the pipe L4 and a mass flow Q2 of steam taken out from the pipe L4. The total amount (Q2 + Q3) with the flow rate Q3 is controlled.

  Next, the feed water merges with warm water (hereinafter referred to as circulating water, 120 ° C. in this embodiment) in the gas-liquid separator 7 sent from the pipe L6 to mix the circulating water and the feed water. Water (100 ° C. in this embodiment) is formed and sent to the medium condenser 3. The mixed water introduced into the medium condenser 3 recovers the heat of the high-temperature and high-pressure medium (heat pump medium) as described above, and generates a gas-liquid two-phase flow (125 ° C. in this embodiment) of hot water and steam. To the gas-liquid separator 7.

  In the gas-liquid separator 7, the gas-liquid two-phase flow of hot water and steam is separated into steam and hot water. And the vapor | steam stored by the gaseous-phase part of the gas-liquid separator 7 opens / closes the on-off valve V1 according to an external demand, and is taken out from the piping L4. Moreover, the warm water stored in the liquid phase part of the gas-liquid separator 7 is circulated and used by mixing with the supply water flowing through the pipe L3 through the pipe L6.

  The on-off valve V2 provided in the pipe L5 connected to the liquid phase part of the gas-liquid separator 7 is periodically or temporarily controlled to blow down for the purpose of preventing the concentration of salt in the circulating water system. Do.

  According to the heat pump type steam generating apparatus of the present invention, the heat pump medium sent to the compressor 2 is heated by the heat pump medium that has passed through the medium condenser 3 by the internal heat exchanger 10, so that the exhaust heat recovery device has a large size. Even without heating or heating with a heater or the like, the temperature of the heat pump medium before the inlet of the compressor 2 can be raised to a superheated steam state. For this reason, condensation of the heat pump medium in the compressor 2 can be effectively prevented without increasing the apparatus cost and the operating cost.

  Next, a second embodiment of the heat pump steam generator to which the present invention is applied will be described with reference to FIG. 2 of the present invention. In addition, the same location as the heat pump type steam generation apparatus of 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits the description.

  In this embodiment, the medium cooler 4 is disposed in the heat pump circulation path 20 in the path between the high-temperature medium section of the internal heat exchanger 10 and the expander 5. It is comprised so that the feed water introduce | transduced into 3 can be preheated.

  According to this embodiment, the feed water (25 ° C.) is preheated (in this embodiment 90 ° C. by a heat pump medium (120 ° C. supercooled liquid in this embodiment)) that has passed through the hot medium section of the internal heat exchanger 10. Therefore, steam can be efficiently generated in the medium condenser 3.

1: Waste heat recovery device 2: Compressor 3: Medium condenser 4: Medium cooler 5: Expander 7: Gas-liquid separator 10: Internal heat exchanger 20: Heat pump circulation paths L1 to L6: Pipes V1, V2: On-off valve

Claims (4)

An exhaust heat recovery unit that recovers heat from an external heat source to heat the medium, a compressor that compresses the medium that has passed through the exhaust heat recovery unit, and transfers the heat of the medium compressed by the compressor to the water to be heated. A heat pump circulation path having a medium condenser that generates a gas-liquid two-phase flow of hot water and steam, and an expander that depressurizes the medium that has passed through the medium condenser to lower the temperature;
A water supply path for introducing supply water to the medium condenser;
A gas-liquid separator that separates the gas-liquid two-phase flow of hot water and steam generated by the medium condenser into water vapor and water;
A vapor extraction path provided in a gas phase portion of the gas-liquid separator;
A heat pump type steam generator comprising a water circulation path connecting the liquid phase part of the gas-liquid separator and the water supply path,
In the superheated steam region of the PH diagram, the medium is a medium whose isentropic line has a larger slope than the saturated steam line and has a critical temperature of 150 ° C. or higher.
In the heat pump circulation path, heat exchange is performed between the medium of the wet steam from the medium condenser toward the expander and the medium of the wet steam from the exhaust heat recovery unit toward the compressor, and is introduced into the compressor. An internal heat exchanger for heating the medium to be heated is disposed, and the medium that has passed through the medium condenser becomes a supercooled liquid in the internal heat exchanger, is introduced into the expander, and passes through the exhaust heat recovery unit The heat-pump-type steam generating apparatus is characterized in that the heated medium becomes superheated steam in the internal heat exchanger and is introduced into the compressor. The medium is n-pentane (C ₅ H ₁₂ ), 1,1,1,3,3-pentafluoropropane (CHF ₂ CH ₂ CF ₃ ), 1,1,1,2,2,3,3- it is one selected from heptafluoro-3-methoxypropane _{(C 3 F 7 OCH 3)} , the heat pump type steam generating device according to claim 1.   The internal heat exchanger is introduced into the compressor until the temperature reaches a target temperature without condensing when the medium is compressed by the compressor and heated to the target temperature. The heat pump type steam generator according to claim 1 or 2, wherein the medium to be heated is heated.   A medium cooler is arranged that preheats the feed water that goes to the medium condenser by exchanging heat between the medium that goes from the internal heat exchanger to the expander and the feed water that goes to the medium condenser. The heat pump type | formula steam generator of any one of Claims 1-3.