JP6066189B2 - Water heating system - Google Patents

Description

  The present invention relates to a feed water heating system using a heat pump driven by an engine.

  Conventionally, as disclosed in Patent Document 1 below, a system capable of heating water supplied to a water supply tank (23) of a boiler (24) using a heat pump (12) is known. In addition, the applicant has proposed a feed water warming system in which the efficiency of the heat pump is further improved as compared with this prior art, and has already filed a patent application (Japanese Patent Application No. 2012-79191).

JP 2010-25431 A (FIGS. 2 and 3)

  The problem to be solved by the present invention is to improve the efficiency of a feed water heating system using a heat pump driven by an engine. Also, the exhaust heat from the engine is used effectively.

  The present invention has been made to solve the above problems, and the invention according to claim 1 is characterized in that a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in an annular manner to circulate a refrigerant, and the evaporation. A heat pump that draws up heat from a heat source fluid in the condenser and heats water in the water supply channel in the condenser, and an engine that drives a compressor of the heat pump, and the water in the water supply channel is a waste heat recovery heat exchanger The waste heat recovery heat exchanger is an indirect heat exchanger between the feed water in the feed water channel and the heat source fluid after passing through the evaporator, and is passed through the supercooler and the condenser in order. The water heater is an indirect heat exchanger for supplying water from the water supply channel to the refrigerant from the condenser to the expansion valve.

  According to the first aspect of the present invention, in the feed water heating system using the heat pump driven by the engine, the feed water in the feed water passage is sequentially passed through the waste heat recovery heat exchanger, the subcooler, and the condenser. On the other hand, the heat source fluid of the heat pump is sequentially passed through the evaporator and the waste heat recovery heat exchanger. The efficiency of the heat pump can be improved by preheating the feed water to the condenser using the waste heat of the heat source fluid after passing through the evaporator and the heat of the refrigerant after passing through the condenser.

  Invention of Claim 2 is further equipped with the jacket heat exchanger which heats the water after passing through the said condenser for cooling of the jacket of the said engine, The water supply of Claim 1 characterized by the above-mentioned It is a heating system.

  According to invention of Claim 2, after heating water supply with a heat pump, it can further heat with exhaust heat at the time of engine jacket cooling.

  Invention of Claim 3 is further equipped with the waste gas heat exchanger which heats the water after passing the said condenser with the waste gas from the said engine, The Claim 1 or Claim 2 characterized by the above-mentioned. This is a water heating system.

  According to the invention described in claim 3, after heating the feed water with the heat pump, it can be further heated with the exhaust gas from the engine.

  According to a fourth aspect of the present invention, the engine is a gas engine, and the amount of gas supplied to the gas engine is adjusted based on the water temperature on the outlet side of the exhaust gas heat exchanger. It is a feed water heating system described in 1.

  According to the fourth aspect of the present invention, even if the flow rate of the water supply passage is changed by adjusting the amount of gas supplied to the gas engine based on the water temperature on the outlet side of the exhaust gas heat exchanger, Can be maintained as desired.

  Invention of Claim 5 is further equipped with the feed water preheater which heats the feed water from the said waste heat recovery heat exchanger to the said subcooler with the waste gas from the said engine. The feed water warming system according to any one of 4.

  According to invention of Claim 5, the efficiency of a heat pump can be improved by heating the water supply to a heat pump beforehand with the exhaust gas from an engine.

  Invention of Claim 6 is further equipped with the neutralization apparatus which neutralizes the heat source fluid after passing the said waste-heat recovery heat exchanger using the waste gas from the said engine. 5. The feed water warming system according to claim 1.

  According to invention of Claim 6, even if the heat source fluid of a heat pump has high alkalinity like the blow water from a boiler, for example, it can neutralize using waste gas. Thereby, the discharge | emission standard of a heat source fluid is satisfied, and the carbon dioxide in exhaust gas can also be reduced.

  Further, the invention according to claim 7 is characterized in that the supply flow rate of the heat source fluid to the evaporator is adjusted based on the temperature of the heat source fluid after passing through the waste heat recovery heat exchanger. It is a feed water heating system of any one of -6.

  According to the seventh aspect of the invention, the exhaust temperature of the heat source fluid can be adjusted as desired.

  ADVANTAGE OF THE INVENTION According to this invention, in the feed water heating system using the heat pump driven with an engine, the efficiency can be improved. Also, exhaust heat from the engine can be effectively utilized.

It is the schematic which shows Example 1 of the feed water heating system of this invention. It is the schematic which shows Example 2 of the feed water heating system of this invention. It is the schematic which shows Example 3 of the feed water heating system of this invention.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of a feed water warming system 1 of the present invention.
The feed water heating system 1 of the present embodiment includes a vapor compression heat pump 2 and an engine 3 that drives the heat pump 2. And the feed water heating system 1 heats the water of the water supply path 4 with the heat pump 2 and warms it using the exhaust heat of the engine 3. The water thus heated is not particularly limited in its use, but is used, for example, as water supply to a boiler.

  The heat pump 2 is configured by sequentially connecting a compressor 5, a condenser 6, an expansion valve 7 and an evaporator 8 in an annular shape. The compressor 5 compresses the gas refrigerant to a high temperature and a high pressure. The condenser 6 condenses and liquefies the gas refrigerant from the compressor 5. Further, the expansion valve 7 allows the liquid refrigerant from the condenser 6 to pass therethrough, thereby reducing the pressure and temperature of the refrigerant. The evaporator 8 evaporates the refrigerant from the expansion valve 7.

  Therefore, in the heat pump 2, the refrigerant takes heat from the outside in the evaporator 8 and vaporizes, while in the condenser 6, the refrigerant dissipates heat to the outside and condenses. Using this, the heat pump 2 draws up heat from the heat source fluid in the evaporator 8 and heats the water in the water supply channel 4 in the condenser 6. The heat source fluid is not particularly limited, but is heat source water (for example, waste hot water) in this embodiment.

  It is preferable that the heat pump 2 further includes a supercooler 9 between the condenser 6 and the expansion valve 7. The subcooler 9 is an indirect heat exchanger between the refrigerant from the condenser 6 to the expansion valve 7 and the feed water to the condenser 6. The subcooler 9 can supercool the refrigerant from the condenser 6 to the expansion valve 7 by supplying water to the condenser 6, and can supply the refrigerant to the condenser 6 by the refrigerant from the condenser 6 to the expansion valve 7. The water supply can be heated. The refrigerant of the heat pump 2 preferably releases latent heat in the condenser 6 and releases sensible heat in the subcooler 9.

  That is, in the condenser 6, the gas refrigerant is condensed into a liquid refrigerant, and the liquid refrigerant is supplied to the subcooler 9, and the liquid refrigerant is further cooled (supercooled) in the subcooler 9. By separating the heat exchangers for refrigerant condensing and supercooling, the heat exchanger can be easily designed, the heat exchanger can be downsized with a simple structure, and the cost can be reduced. In addition, a general-purpose heat exchanger can be used.

  In addition, in the heat pump 2, an accumulator is installed on the inlet side of the compressor 5, an oil separator is installed on the outlet side of the compressor 5, or the outlet side of the condenser 6 (the condenser 6 and the subcooler 9). A receiver may be installed between the two).

  It is preferable that the feed water heating system 1 further includes a waste heat recovery heat exchanger 10. The waste heat recovery heat exchanger 10 is an indirect heat exchanger for supplying water to the subcooler 9 and heat source water after passing through the evaporator 8. Accordingly, the water in the water supply channel 4 is passed through the waste heat recovery heat exchanger 10, the subcooler 9, and the condenser 6 in order by the water supply pump 11.

  On the other hand, the heat source water is passed through the evaporator 8 via the heat source supply path 12 and then passed to the waste heat recovery heat exchanger 10. In the present embodiment, the heat source supply path 12 is provided with a heat source supply pump 13 on the upstream side of the evaporator 8, and the heat source supply pump 13 is operated to convert the heat source water into the evaporator 8 and waste heat. It can be passed through the recovered heat exchanger 10 in order.

  By passing the heat source water through the waste heat recovery heat exchanger 10 after passing the evaporator 8 first, compared with the case where the heat source water is passed through the evaporator 8 after passing the waste heat recovery heat exchanger 10 first. The evaporation temperature (that is, the evaporation pressure) of the refrigerant in the evaporator 8 can be increased, the pressure ratio of the compressor 5 can be reduced, and energy can be saved.

  The engine 3 drives the compressor 5 of the heat pump 2. In the illustrated example, the power of the engine 3 drives the compressor 5 via the belt 14. The configuration of the engine 3 is not particularly limited. For example, the engine 3 is a gas engine or a diesel engine, and exhausts exhaust gas when driven. Further, the engine 3 of this embodiment is a water-cooled type including a jacket 15 as will be described later.

  The feed water heating system 1 is preferably configured to be able to heat the water in the feed water channel 4 by recovering heat from jacket cooling water or exhaust gas of the engine 3. Therefore, it is preferable to provide one or both of the jacket heat exchanger 16 and the exhaust gas heat exchanger 17.

  The jacket heat exchanger 16 is an indirect heat exchanger for heating the water after passing through the condenser 6 by using it for cooling the jacket 15 of the engine 3. At this time, the water from the condenser 6 may flow directly to the jacket 15 of the engine 3 (that is, the jacket 15 itself may be used as the jacket heat exchanger 16). It is preferable to circulate a liquid (jacket cooling water) between them and exchange heat between the circulating liquid and the water in the water supply channel 4 by the jacket heat exchanger 16. Thereby, the feed water from the condenser 6 is heated with the circulating fluid. On the contrary, the circulating fluid is cooled by the water supply from the condenser 6, and consequently the jacket 15 and the engine 3 are cooled.

  The exhaust gas heat exchanger 17 is an indirect heat exchanger that is provided in the exhaust gas path 18 from the engine 3 and warms the water after passing through the jacket heat exchanger 16 with the exhaust gas from the engine 3. The feed water heated by the jacket heat exchanger 16 is supplied to the exhaust gas heat exchanger 17, further heated by exchanging heat with the exhaust gas from the engine 3, and sent to a hot water use facility (for example, a boiler feed water tank).

  A first temperature sensor 19 may be provided on the outlet side of the exhaust gas heat exchanger 17 in the water supply path 4, and the output of the engine 3 may be controlled based on the temperature detected by the first temperature sensor 19. In this embodiment, the engine 3 is a gas engine, and the amount of gas supplied to the gas engine 3 is adjusted based on the temperature detected by the first temperature sensor 19. By adjusting the amount of gas supplied to the gas engine 3 based on the water temperature on the outlet side of the exhaust gas heat exchanger 17, the temperature of the tapping water can be maintained as desired even if the water flow rate of the water supply channel 4 changes. .

  The supply flow rate of the heat source water to the evaporator 8 may be adjustable based on the temperature of the heat source water after passing through the waste heat recovery heat exchanger 10. Specifically, a second temperature sensor 20 is provided on the outlet side of the waste heat recovery heat exchanger 10 in the heat source supply path 12, and the heat source supply pump 13 is inverter-controlled based on the detected temperature of the second temperature sensor 20. Or the opening degree of the valve provided in the heat source supply path 12 may be adjusted. Thereby, the discharge temperature of the heat source water can be adjusted as desired.

  FIG. 2 is a schematic diagram showing Example 2 of the feed water heating system 1 of the present invention. The feed water warming system 1 of the second embodiment is basically the same as that of the first embodiment. Therefore, in the following description, differences between the two will be mainly described, and corresponding portions will be described with the same reference numerals.

  In the second embodiment, the feed water preheater 21 is further provided in the feed water path 4 from the waste heat recovery heat exchanger 10 to the supercooler 9. The feed water preheater 21 is an indirect heat exchanger between the feed water from the waste heat recovery heat exchanger 10 to the supercooler 9 and the exhaust gas from the engine 3. The exhaust gas supplied to the feed water preheater 21 may be exhaust gas after passing through the exhaust gas heat exchanger 17 as indicated by a solid line, or from the exhaust gas heat exchanger 17 in the exhaust gas path 18 as indicated by a two-dot chain line. You may branch and supply from upstream. In any case, the efficiency of the heat pump 2 can be improved by preheating the water supply to the heat pump 2 with the exhaust gas from the engine 3.

  Also in the second embodiment, similarly to the first embodiment, the amount of gas supplied to the engine 3 may be adjusted based on the water temperature on the outlet side of the exhaust gas heat exchanger 17. Similarly to the first embodiment, the supply flow rate of the heat source water to the evaporator 8 may be adjusted based on the heat source water temperature on the outlet side of the waste heat recovery heat exchanger 10. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  FIG. 3 is a schematic view showing a third embodiment of the feed water warming system 1 of the present invention. The feed water warming system 1 of the third embodiment is basically the same as the first embodiment. Therefore, in the following description, differences between the two will be mainly described, and corresponding portions will be described with the same reference numerals.

  In the third embodiment, the heat source water that has passed through the waste heat recovery heat exchanger 10 is further provided with a neutralizer 22 that neutralizes the exhaust water from the engine 3. The neutralization device 22 is supplied with the heat source water after passing through the waste heat recovery heat exchanger 10 and also supplied with the exhaust gas after passing through the exhaust gas heat exchanger 17.

  For example, when the heat source water is highly alkaline water such as boiler blow water, the specified drainage standard is not satisfied as it is. Therefore, by using carbon dioxide in the exhaust gas as a neutralizing agent, the heat source water can be neutralized with the exhaust gas in the neutralizing device 22 and the emission standard can be satisfied. Thereby, the amount of carbon dioxide in the exhaust gas can also be reduced.

  Also in the third embodiment, similarly to the first embodiment, the amount of gas supplied to the engine 3 may be adjusted based on the water temperature on the outlet side of the exhaust gas heat exchanger 17. Moreover, also in the present Example 3, the feed water preheater 21 can be installed similarly to the said Example 2. FIG. In that case, the heat source water after passing through the waste heat recovery heat exchanger 10 may be neutralized using the exhaust gas after passing through the feed water preheater 21. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  The feed water warming system 1 of the present invention is not limited to the configuration of the above embodiment, and can be changed as appropriate. For example, in the above-described embodiment, an example in which heat source water is used as the heat source of the heat pump 2 has been described. However, the heat source fluid of the heat pump 2 is not limited to heat source water, and various fluids such as air and exhaust gas can be used. However, while the heat source fluid gives heat (sensible heat) to the refrigerant of the heat pump 2 in the evaporator 8, the heat source fluid itself falls in temperature, and then gives heat (sensible heat) to the feed water in the waste heat recovery heat exchanger 10. The fluid itself with a temperature drop is preferable.

DESCRIPTION OF SYMBOLS 1 Feed water heating system 2 Heat pump 3 Engine 4 Feed water path 5 Compressor 6 Condenser 7 Expansion valve 8 Evaporator 9 Subcooler 10 Waste heat recovery heat exchanger 11 Feed water pump 12 Heat source supply path 13 Heat source supply pump 14 Belt 15 Jacket 16 Jacket heat exchanger 17 Exhaust gas heat exchanger 18 Exhaust gas path 19 First temperature sensor 20 Second temperature sensor 21 Feed water preheater 22 Neutralizer

Claims (7)

A compressor, a condenser, an expansion valve and an evaporator sequentially connected in a ring to circulate the refrigerant, draw up heat from a heat source fluid in the evaporator, and heat the water in the water supply channel in the condenser;
An engine that drives the compressor of this heat pump,
The water in the water supply channel is passed through a waste heat recovery heat exchanger, a supercooler, and the condenser in order,
The waste heat recovery heat exchanger is an indirect heat exchanger between the water supply of the water supply channel and the heat source fluid after passing through the evaporator,
The subcooler is an indirect heat exchanger for supplying water from the water supply channel to the refrigerant from the condenser to the expansion valve. The feed water heating system according to claim 1, further comprising a jacket heat exchanger that heats the water after passing through the condenser by using it for cooling the jacket of the engine. The feed water warming system according to claim 1, further comprising an exhaust gas heat exchanger that heats water after passing through the condenser with exhaust gas from the engine. The engine is a gas engine;
The feed water heating system according to claim 3, wherein an amount of gas supplied to the gas engine is adjusted based on a water temperature on an outlet side of the exhaust gas heat exchanger. The water supply preheater which heats the water supply from the waste heat recovery heat exchanger to the supercooler with the exhaust gas from the engine is further provided. Water heating system. The neutralization apparatus which neutralizes the heat source fluid after passing through the waste heat recovery heat exchanger using the exhaust gas from the engine is further provided. Water heating system. The supply water according to any one of claims 1 to 6, wherein a supply flow rate of the heat source fluid to the evaporator is adjusted based on a temperature of the heat source fluid after passing through the waste heat recovery heat exchanger. Heating system.

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