JP4829676B2 - Heat source system - Google Patents

Description

The present invention is a compression heat pump circuit in which a refrigerant circulates in order of a compressor that compresses the refrigerant, a condenser that dissipates heat from the refrigerant, an expansion valve that expands the refrigerant, and an evaporator that absorbs heat from the refrigerant,
The present invention relates to a heat source system including an exhaust gas path that supplies exhaust gas discharged from a combustion device that burns fuel as a heat source of the evaporator.

In recent years, from the viewpoint of protecting the ozone layer and preventing global warming, natural refrigerants such as carbon dioxide are used instead of artificial refrigerants such as Freon, and the operating pressure of the compressor (that is, the refrigerant discharge pressure) Refrigeration that forcibly moves heat from the heat absorber to the radiator side by utilizing heat absorption and heat dissipation when changing the state of the natural refrigerant between a gas phase state and a gas-liquid two-phase state as a supercritical pressure A heat source system having a compression heat pump circuit that operates in a cycle (hereinafter referred to as “supercritical refrigeration cycle”) has been put into practical use.
Further, the compression heat pump circuit operating in such a supercritical refrigeration cycle has a coefficient of performance (hereinafter referred to as “COP”) indicating a ratio of the refrigeration capacity to the amount of work applied to the compressor compared with about 4. In general, it is excellent in energy saving, and generally, outside air can be supplied as a heat source for the evaporator, and hot water can be heated to a relatively high temperature (80 ° C. to 95 ° C.) in the condenser. The heated hot water can be used as a heat source water for hot water supply or heating.

In addition, as a heat source system having the compression heat pump circuit as described above, a so-called cogeneration system that generates heat and electric power is provided by including a fuel cell, and is further discharged from a reformer of the fuel cell. A heat source system having an exhaust gas path for supplying exhaust gas as a heat source of an evaporator of a compression heat pump circuit is known (see, for example, Patent Document 1).
Such a heat source system supplies the exhaust gas of the fuel cell as the heat source of the evaporator through the exhaust gas passage, thereby improving the overall thermal efficiency by using as much of the exhaust heat of the fuel cell as possible, and the refrigerant vaporization performance in the evaporator It is said that it is possible to improve the size and the size of the evaporator.
In addition, the COP may decrease due to a decrease in the outside air temperature and frost formation in the evaporator in winter, etc., but if the relatively high temperature exhaust gas is supplied to the evaporator as described above, the evaporation will occur. The defrosting of the vessel can be performed to prevent the COP from decreasing.

  Further, the heat source system described in Patent Document 1 is configured to drive the compressor of the compression heat pump circuit with surplus power exceeding the power load among the generated power generated by the fuel cell. With such a configuration, even when the heat load and the power load are imbalanced depending on the season or time zone, the fuel cell can generate heat and power by setting an appropriate thermoelectric ratio. It is possible to improve the operating rate.

JP 2005-337516 A (Claim 2 etc.)

However, in the heat source system described in Patent Document 1, in the case where a combustion device that burns fuel is provided instead of the fuel cell, for example, an engine that outputs the driving force of the compressor, the exhaust is discharged from the combustion device. The exhaust gas is supplied as a heat source of the evaporator through the exhaust gas passage. Since the exhaust gas contains a corrosive gas such as NOx and SOx, the evaporator with the corrosive gas is used. Corrosion of the constituent materials becomes a problem.
In addition, in order to prevent such corrosion, an expensive exhaust gas treatment device for removing the corrosive gas is installed in the exhaust gas passage, or the operating condition of the combustion device is changed to a corrosive gas at the expense of efficiency. It was necessary to set the emission to be reduced.

  The present invention has been made in view of the above problems, and its purpose is to exhaust gas discharged from a combustion device that burns fuel, such as an engine that outputs a driving force of a compressor of a compression heat pump circuit. In the heat source system that supplies the heat source of the evaporator of the compression heat pump circuit through the exhaust gas passage, the low-cost and simple configuration of the constituent material of the evaporator by the corrosive gas contained in the exhaust gas while maintaining high efficiency. The object is to provide a technique capable of preventing corrosion.

In order to achieve the above object, the heat source system according to the present invention includes a compressor that compresses the refrigerant, a condenser that dissipates heat from the refrigerant, an expansion valve that expands the refrigerant, and an evaporator that absorbs heat from the refrigerant. A compression heat pump circuit that circulates each in turn,
An exhaust gas path that supplies exhaust gas discharged from a combustion device that burns fuel as a heat source of the evaporator, the first characteristic configuration of which is the combustion device and the evaporation in the exhaust gas path A latent heat recovery heat exchanger that preheats feed water by the latent heat of water vapor contained in the exhaust gas flowing between the condenser and a condensed water recovery unit that recovers condensed water generated in the latent heat recovery heat exchanger , the exhaust gas path Between the combustion device and the evaporator in
The exhaust gas flowing through the exhaust gas passage is configured to be guided to the evaporator after the corrosive gas is absorbed by the condensed water recovered by the condensed water recovery unit .

That is, in the exhaust gas path, the latent heat is recovered by recovering the latent heat in a form in which the latent heat of the water vapor contained in the exhaust gas discharged from the combustion device is heated by the latent heat recovery heat exchanger. Can be condensed to generate condensed water.
The latent heat recovery heat exchanger and the condensed water recovery unit are provided between the combustion device and the evaporator in the exhaust gas path, and the exhaust gas flowing through the exhaust gas path is the condensed water recovered by the condensed water recovery part. Since it is configured to be guided to the evaporator after the corrosive gas is absorbed, the corrosive gas such as NOx and SOx contained in the exhaust gas can be absorbed in the condensed water, and the compression type Corrosive gas supplied to the evaporator of the heat pump circuit can be greatly reduced, and corrosion due to the corrosive gas of the constituent material of the evaporator can be suppressed. Moreover, the condensed water which absorbed the said corrosive gas is collect | recovered in the said condensed water collection | recovery part, for example, it can pass through the neutralizer which uses calcium carbonate etc., and can be discarded appropriately.
On the other hand, in the latent heat recovery heat exchanger, relatively low temperature water supply (water supplied from the water supply) is preheated by the latent heat of water vapor contained in the exhaust gas, and for example, this preheated water supply is supplied to the consumer. The overall heat efficiency can be maintained at a high level by effectively utilizing the latent heat of water vapor contained in the water.
Furthermore, since the exhaust gas supplied to the evaporator is kept relatively warm even after the latent heat is recovered by the latent heat recovery heat exchanger, the refrigerant vaporization performance in the evaporator is improved, and the evaporator It is possible to reduce the size and improve the COP of the compression heat pump circuit.

The second feature configuration of the heat source system according to the present invention includes, in addition to the first feature configuration, a latent heat recovery state adjustment unit capable of adjusting a latent heat recovery state by the latent heat recovery heat exchanger,
Frost state determination means for determining a frost state in the evaporator;
And a control unit that executes frost prevention control for controlling the latent heat recovery state adjusting unit based on the determination result of the frosting state determining unit.

That is, by adjusting the latent heat recovery state by the latent heat recovery state adjusting means, the temperature of the exhaust gas supplied to the evaporator through the exhaust gas path, and the removal state of the corrosive gas from the exhaust gas in the exhaust gas path, It can be adjusted to an appropriate one.
Further, the frosting state determination means determines whether or not frosting has occurred in the evaporator to such an extent that the refrigerant vaporization performance may be deteriorated, for example, based on the temperature near the evaporator or the outside air temperature in the exhaust gas passage. Can do.
And by the said control means, when the said frost prevention control is performed and it determines with the said evaporator having formed frost, decreasing a latent-heat recovery amount (including the state which does not collect | recover latent heats), By controlling the latent heat recovery state by the latent heat recovery heat exchanger in the exhaust gas path based on the determination result of the frosting state determination means, a so-called defrost operation is performed to satisfactorily melt the frost attached to the evaporator in winter. It is possible to suppress a decrease in refrigerant vaporization performance due to frost formation in the evaporator. Therefore, the COP of the compression heat pump circuit can always be kept high.
Further, when such frost prevention control is executed, the amount of condensed water generated is reduced by reducing the amount of latent heat recovered by the latent heat recovery heat exchanger, and is included in the exhaust gas supplied to the evaporator. Although the corrosive gas increases, the frost attached to the evaporator is melted by the defrost operation and water is generated, and the corrosive gas can be absorbed and removed by the water. Corrosion of the constituent material can be suppressed.

A third characteristic configuration of the heat source system according to the present invention includes, in addition to any of the first to second characteristic configurations described above, latent heat recovery state adjusting means capable of adjusting a latent heat recovery state by the latent heat recovery heat exchanger; ,
Corrosive gas state determining means for determining a corrosive gas state in the exhaust gas flowing downstream of the latent heat recovery heat exchanger in the exhaust gas path;
There is a control means for executing corrosion prevention control for controlling the latent heat recovery state adjustment means based on the determination result of the corrosive gas state determination means.

That is, by adjusting the latent heat recovery state by the latent heat recovery state adjusting means, the temperature of the exhaust gas supplied to the evaporator through the exhaust gas path, and the removal state of the corrosive gas from the exhaust gas in the exhaust gas path, It can be adjusted to an appropriate one.
Further, the corrosive gas state determination means allows the evaporator to be included in the exhaust gas supplied to the evaporator by, for example, the NOx concentration detected by the NOx sensor installed downstream of the latent heat recovery heat exchanger in the exhaust gas path. It can be determined whether or not the corrosive gas is present to the extent that there is a concern about corrosion.
Then, the control means executes the corrosion prevention operation to increase the latent heat recovery amount when it is determined that the corrosive gas is present in the exhaust gas to the extent that corrosion in the evaporator is concerned. As described above, by controlling the latent heat recovery state adjusting means based on the determination result of the corrosive gas state determining means, the amount of condensed water generated is increased and a large amount of corrosive gas is absorbed by the condensed water. And corrosion in the evaporator can be reliably prevented.

A fourth feature configuration of the heat source system according to the present invention includes, in addition to any one of the first to third feature configurations, an exhaust heat recovery heat exchanger that heats hot water with exhaust heat of the combustion device,
A circulation pipe that circulates hot water heated by the exhaust heat recovery heat exchanger as heat source water in a form that can be taken out by the consumer for the consumer,
The condenser is configured to heat feed water by heat dissipation of the refrigerant;
The water supply heated by the condenser is supplied to the return path side of the circulation pipe, and the water preheated by the latent heat recovery heat exchanger is supplied to the return path side of the circulation pipe. It is in.

That is, the hot water is heated by the exhaust heat of the combustion device discharged as sensible heat of cooling water for cooling the combustion device, for example, by the exhaust heat recovery heat exchanger, and the heated hot water is heated by the circulation pipe. By circulating the hot water that has become the heat source water to the consumer, the consumer can use the heat source water taken out from the circulation pipe for hot water supply or perform heating by radiating heat from the heat source water.
Further, in the condenser, since the heat of the refrigerant which has been compressed by the compressor and becomes very high temperature can be heated to a relatively high temperature, the relatively low temperature water supply can be heated to a high temperature. It is possible to replenish the heat source water heated by the exhaust heat recovery heat exchanger in the piping to the customer side and supply it to the customer side together with the heat source water having a high temperature. it can.
On the other hand, in the latent heat recovery heat exchanger, the feed water cannot be preheated to a very high temperature due to the latent heat of water vapor contained in the exhaust gas. Therefore, the preheated feed water is circulated through the consumers in the circulation pipe. Heat source water whose temperature has decreased may be replenished to the return path side, which is the side returning to the exhaust heat recovery heat exchanger side, and supplied to the exhaust heat recovery heat exchanger side and heated to a high temperature together with the heat source water whose temperature has decreased. it can.

The fifth feature configuration of the heat source system according to the present invention includes, in addition to the fourth feature configuration, a water receiving tank for storing the feed water preheated by the latent heat recovery heat exchanger,
The water supply stored in the water receiving tank is configured to replenish the return path side of the circulation pipe,
There is an overpressure prevention means for preventing the occurrence of overpressure in the circulation pipe by returning the heat source water of the circulation pipe to the water receiving tank.

That is, the water supply tank preheated by the latent heat recovery heat exchanger is stored in the water receiving tank, for example, a water supply pipe for supplying the water supply to a consumer is provided, and the water supply once stored in the water receiving tank is stored. It can be supplied to customers through water supply pipes and used.
Further, the water supply stored in the water receiving tank can be replenished to the return path side of the above-described circulation pipe and supplied to the exhaust heat recovery heat exchanger side together with the heat source water whose temperature has been lowered to be heated to a high temperature. .
In the circulation piping, for example, there is a concern that the amount of water supply replenished after being heated by the condenser exceeds the amount of heat source water taken out by the consumer. Such an excessive pressure increase in the circulation pipe can be prevented by returning the heat source water of the circulation pipe to the water receiving tank by the pressure increase prevention means.
In addition, for example, when a hot water storage tank is provided that stores heat source water in a form that forms temperature stratification from the upper part connected to the return path side of the circulation pipe to the lower part connected to the return path side of the circulation pipe In addition, since the over-pressurization of the hot water storage tank can be prevented by the over-pressurization preventing means, it is not necessary to separately install a relief valve in the hot water storage tank.

A sixth characteristic configuration of the heat source system according to the present invention is an engine in which the combustion device outputs a driving force of the compressor, in addition to any one of the first to fifth characteristic configurations described above.
A generator driven by the engine to generate electric power;
And an electric motor that operates by the electric power generated by the generator and drives the compressor.

In other words, as described above, heat can be generated and electric power can be generated by driving a generator by an engine provided as a combustion device, so that a so-called cogeneration system can be configured. The electric power and heat to be used can be effectively used in the compression heat pump circuit to greatly improve the overall overall thermal efficiency.
Furthermore, if the power of the compressor, that is, the output of the compression heat pump circuit is controlled so that the output of the engine becomes stable (for example, constant), the engine can be operated with high efficiency. Deterioration caused by engine output fluctuations can be suppressed.

An embodiment of a heat source system according to the present invention will be described with reference to the drawings.
1 is a schematic configuration diagram of the heat source system 100, and FIG. 2 is a conceptual diagram of a heat supply system including the heat source system 100.

  As shown in FIG. 2, the heat source system 100 is installed in a heat supply system that supplies heat to each residence 101 (an example of a consumer) in the apartment house 105, and each residence 101 in the apartment house 105. It is configured as a cogeneration system that generates electricity and heat used in the system.

In addition, the heat supply system is dispersedly installed in the circulation pipe 102 that circulates the heat source water HW heated to about 80 ° C. to about 80 ° C. by the heat generated by the heat source system 100, and the common part of each residence 101. In addition, the heat of the heat source water HW that circulates in the circulation pipe 102 in each residence 101 is primarily stored in the heat storage device 110, and the heat stored in the heat storage device 110 is the living part of each residence 101. Are consumed as hot water supply A1, heating B1, and bath replenishment B2. Further, the heat supply system includes a water supply pipe 103 that supplies a water supply SW preheated by heat generated by the heat source system 100 to each residence 101.
The heat source water HW generally uses water, but separately uses another fluid such as a latent heat storage material slurry in which the latent heat storage material is suspended or a fluid containing microcapsules of the latent heat storage material. It doesn't matter.

Next, a detailed configuration of the heat source system 100 will be described with reference to FIG.
As shown in FIG. 1, the heat source system 100 includes a compression heat pump circuit 1, an engine 2 configured as a combustion device for burning fuel, and an exhaust gas path 3 through which exhaust gas E discharged from the engine 2 flows. Further, a control device 70 for performing various controls and the like is provided.

  The compression heat pump circuit 1 includes a refrigerant X that is carbon dioxide as a natural refrigerant, a compressor 10 that compresses the refrigerant X, a condenser 11 that dissipates heat from the refrigerant X, an expansion valve 12 that expands the refrigerant X, and a refrigerant X. Each of them is configured to circulate in the order of the evaporator 13 that absorbs heat.

  The compression heat pump circuit 1 using carbon dioxide as the refrigerant X uses the operating pressure of the compressor 10 (that is, the discharge pressure of the refrigerant X) as a supercritical pressure of a natural refrigerant, and the refrigerant X is in a gas phase state and a gas. It operates in a supercritical heat pump cycle in which heat is forcibly transferred from the evaporator 13 to the condenser 11 side by utilizing heat absorption / radiation when changing the state between the liquid two-phase state. Specifically, in the compression heat pump circuit 1, the refrigerant X in a gas phase is compressed by the compressor 10 to be a high temperature and a high pressure, and the high temperature and high pressure refrigerant X is radiated by the condenser 11 to be cooled, and the cooled refrigerant X is depressurized by the expansion valve 12 to be in a gas-liquid two-phase state, and the gas-liquid two-phase refrigerant X is absorbed by the evaporator 13 to be heated to a gas-phase state. About the structure like this, the structure similar to the compression heat pump system which operate | moves with a well-known supercritical heat pump cycle is employable.

The engine 2 is operated by burning a fuel G, which is a natural gas city gas, and outputs a shaft output as a driving force of the compressor 10.
Further, a generator 20 that is driven by the shaft output of the engine 2 and an electric motor 15 that drives the compressor 10 are provided, and the electric motor 15 is driven by the electric power generated by the generator 20, The shaft output of the engine 2 is used as the driving force of the compression heat pump circuit 1.
The electric power generated by the generator 20 is mainly supplied to the electric power load in the apartment house 105, and the surplus electric power, that is, the electric power obtained by subtracting the electric power consumption of the electric power load from the generated electric power is supplied to the electric motor 15. Thus, the compressor 10 of the compression heat pump circuit 1 is driven.

  The cooling system of the engine 2 employs a water cooling system that is cooled by engine cooling water JW that circulates through the cooling water circuit 22 by the operation of the pump 23. The cooling water circuit 22 is provided with an exhaust heat recovery heat exchanger 25 that heats the hot water with the exhaust heat of the engine 2 discharged as sensible heat of the engine coolant JW.

Then, by the operation of the pump 26, the heat source water HW taken out from the return path 102r side of the circulation pipe 102 is heated by the heat exchange with the engine cooling water JW in the exhaust heat recovery heat exchanger 25 and heated. The heat source water HW is supplied to the outgoing path 102 g side of the circulation pipe 102.
Further, the supply amount of the heat source water HW to the exhaust heat recovery heat exchanger 25 is such that the temperature of the engine cooling water JW discharged from the exhaust heat recovery heat exchanger 25 and supplied to the engine 2 can cool the engine 2. It is adjusted to an appropriate temperature.

  Furthermore, an auxiliary heat source device 28 is provided that can heat the heat source water HW that burns the fuel G and is discharged from the exhaust heat recovery heat exchanger 25 and supplied to the forward path 102g of the circulation pipe 102. The amount of fuel supplied to the machine 28 is adjusted so that the temperature of the heat source water HW supplied to the outgoing path 102g of the circulation pipe 102 becomes a set temperature (for example, 80 ° C.).

Further, the condenser 11 of the compression heat pump circuit 1 is configured to heat the feed water SW by the heat radiation of the refrigerant X, and the heated feed water SW serves as the heat source water HW as the outgoing path 102g of the circulation pipe 102. It is replenished to the side.
On the other hand, on the return path 102r side of the circulation pipe 102, the water supply SW stored in the water receiving tank 50 is supplied through the water supply pump 51 and the check valve 52, and together with the heat source water HW returned from each residence 101, exhaust heat is discharged. After being heated to a high temperature by the recovery heat exchanger 25, it is circulated to each residence 101 as the heat source water HW.
Therefore, even when the heat source water HW circulating through the circulation pipe 102 is consumed in each residence 101, the heat source water HW is appropriately supplied from the condenser 11 and the water receiving tank 50 side.

Furthermore, the hot water storage tank 60 for storing the heat source water HW in a form that forms a temperature stratification from the upper part connected to the return path 102g side of the circulation pipe 102 to the lower part connected to the return path 102r side of the circulation pipe 102. Is provided.
That is, the relatively low temperature heat source water HW stored in the lower side of the hot water tank 60 is supplied to the exhaust heat recovery heat exchanger 25 and the auxiliary heat source unit 28 by the pump 26 and heated to a high temperature of about 80 ° C. Later, it is returned to the upper side of the hot water tank 60.
Moreover, the high-temperature heat source water HW stored above the hot water tank 60 is supplied to each residence 101 by the pump 61 through the outgoing path 102g of the circulation pipe 102, and returns from each residence 101 through the return path 102r of the circulation pipe 102. The heated heat source water HW is stored below the hot water tank 60.
Therefore, in the hot water storage tank 60, the high temperature heat source water HW is stored on the upper side, and the low temperature heat source water HW is stored on the lower side, so that temperature stratification is formed.

  The exhaust gas path 3 is formed so as to supply a relatively high temperature exhaust gas E discharged from the engine 2 as a heat source of the evaporator 13 of the compression heat pump circuit 1. The latent heat recovery heat exchanger 31 that preheats the feed water by the latent heat of water vapor contained in the exhaust gas E flowing between the engine 2 and the evaporator 13 in the exhaust gas path 3 and the condensed water CW generated in the latent heat recovery heat exchanger 31 are A condensed water recovery unit 32 for recovery is provided.

The latent heat recovery heat exchanger 31 is configured by disposing, in the exhaust gas path 3, a heat transfer pipe through which the water supply SW is supplied from the water receiving tank 50 through the water supply pump 51 and the check valve 52. The latent heat of the water vapor contained in the exhaust gas E is recovered in a form in which the feed water SW circulating in the heat transfer tube is heated by the latent heat of the exhaust gas E flowing.
In addition, when supplying the feed water SW from the water receiving tank 50 to the latent heat recovery heat exchanger 31, the feed water SW may be supplied not through the feed water pump 51 and the check valve 52 but through a separately provided pump or the like. I do not care.

Further, when the latent heat of the water vapor contained in the exhaust gas E is recovered in this way by the latent heat recovery heat exchanger 31, the water vapor is condensed to generate condensed water CW, and NOx and SOx contained in the exhaust gas E are generated. Corrosive gas such as is absorbed by the condensed water CW.
And the condensed water CW which absorbed corrosive gas is collect | recovered by the said condensed water collection | recovery part 32, For example, it can discard after performing an appropriate process.

Therefore, the exhaust gas E flowing in the downstream side of the latent heat recovery exchanger 31 in the exhaust gas path 3 has a greatly reduced content of exhaust corrosive gas, and the temperature of the latent heat recovery heat exchanger 31 has decreased, but is still outside. It will be warmer than.
Since the warm exhaust gas E that contains almost no corrosive gas is supplied as a heat source of the evaporator 13, the corrosion of the constituent material of the evaporator 13 by the corrosive gas is suppressed, and further, the evaporator As the vaporization performance of the refrigerant 13 is improved, the evaporator 13 is relatively reduced in size, and further, the COP of the compression heat pump circuit 1 is improved.

  Further, the water supply SW that has become warm due to the recovery of the latent heat of the exhaust gas E by the latent heat recovery heat exchanger 31 is returned to the water receiving tank 50, and is stored in the water receiving tank 50 and supplied to each residence 101. The feed water SW is preheated and the overall heat efficiency of the entire heat supply system is maintained high.

Further, as a latent heat recovery state adjusting means capable of adjusting the latent heat recovery state of the exhaust gas E by the latent heat recovery heat exchanger 31, an adjustment valve 34 for adjusting the supply amount of the feed water SW to the latent heat recovery heat exchanger 31 is provided. Yes.
That is, the amount of latent heat recovered from the exhaust gas E in the latent heat recovery heat exchanger 31 is reduced by reducing the opening of the adjustment valve 34 and decreasing the supply amount of the feed water SW to the latent heat recovery heat exchanger 31. Conversely, by increasing the opening of the regulating valve 34 and increasing the supply amount of the feed water SW to the latent heat recovery heat exchanger 31, the exhaust gas E from the exhaust gas E in the latent heat recovery heat exchanger 31 is increased. The amount of latent heat recovery is increased.

Moreover, the temperature sensor 35 which detects the temperature of the evaporator 13 vicinity in the exhaust gas path 3 is provided, and the control apparatus 70 determines the frost formation state in the evaporator 13 based on the detection result of the said temperature sensor 35. It is comprised so that it may function as the frost formation state determination means 71. FIG.
That is, for example, immediately after the start of operation in winter, when the temperature near the evaporator 13 detected by the temperature sensor 35 is below freezing point, the frosting state determination means 71 forms frost in the evaporator 13. Conversely, when the temperature near the evaporator 13 detected by the temperature sensor 35 is not below freezing, it is determined that the evaporator 13 is not frosted.
Instead of the temperature sensor 35 for detecting the temperature in the vicinity of the evaporator 12, a temperature sensor for detecting the temperature of another part of the exhaust gas passage 3, the outside air temperature, or the like is provided. You may comprise so that the frost formation state in the evaporator 13 may be determined based on the detection result of a sensor.

And the control means 73 which the control apparatus 70 functions is based on the determination result of the said frost state determination means 71, and performs the frost prevention control which controls the adjustment valve 34 as the said latent heat recovery state adjustment means. It is configured.
That is, when the control unit 73 determines that the evaporator 13 is frosted by the frosting state determination unit 71 in the frost prevention control, the control unit 73 sets the opening degree of the adjustment valve 34 to a normal set opening degree. Since the amount of latent heat recovered from the exhaust gas E in the latent heat recovery heat exchanger 31 is decreased, the temperature of the exhaust gas E supplied to the evaporator 13 rises and frost adhering to the evaporator 13 is reduced. A so-called defrosting operation that melts well is performed.
Further, when the control means 73 executes the frosting prevention control, the latent heat recovery amount of the latent heat recovery heat exchanger 31 is reduced and the generation amount of the condensed water CW is reduced, so that it is supplied to the evaporator 13. The corrosive gas contained in the exhaust gas E increases. However, since the frost adhering to the evaporator 13 is melted by the defrost operation and water is generated, the corrosive gas contained in the exhaust gas E is well absorbed in the water, so that the evaporator Corrosion of 13 constituent materials is satisfactorily suppressed.

A NOx sensor 36 for detecting NOx as a corrosive gas in the exhaust gas E flowing downstream of the latent heat recovery heat exchanger 31 in the exhaust gas path 3 is provided, and the control device 70 detects the detection result of the NOx sensor 36. Is configured to function as corrosive gas state determination means 72 for determining the corrosive gas state in the exhaust gas E.
That is, the corrosive gas state determination means 72 determines whether or not the corrosive gas is present to the extent that corrosion in the evaporator 13 is a concern based on the detection result of the NOx sensor 36.

And the control means 73 which the control apparatus 70 functions is based on the determination result of the said corrosive gas state determination means 72, and performs the corrosion prevention control which controls the adjustment valve 34 as the said latent heat recovery state adjustment means. It is configured.
That is, when the control means 73 determines that corrosive gas is present in the exhaust gas E by the corrosive gas state determination means 72 in the corrosion prevention control, the control means 73 sets the opening degree of the adjustment valve 34 to a normal value. Since the latent heat recovery amount from the exhaust gas E in the latent heat recovery heat exchanger 31 is increased more than the set opening, the amount of condensed water CW generated increases, and a lot of corrosive gas is absorbed by the condensed water CW. Thus, corrosion in the evaporator 13 is reliably prevented.

In addition, a relief valve 38 that opens when the pressure in the return path 102r of the circulation pipe 102 exceeds the allowable pressure in a form that bypasses the adjustment valve 34 that adjusts the supply amount of the feed water SW to the latent heat recovery heat exchanger 31. Is provided.
The relief valve 38 returns the heat source water HW of the circulation pipe 102 to the water receiving tank 50 through the latent heat recovery heat exchanger 31, thereby preventing the overpressure of the circulation pipe 102 and the hot water tank 60 from occurring. It functions as a prevention means.

In the heat source system 100 shown in FIG. 1 described in the above embodiment, the simulation results of the heat balance of each part when operated in winter will be described below as an example.
The engine 2 is supplied with natural gas city gas (15 ° C., 6.6 Nm ³ / h) and air (7 ° C., 116 Nm ³ / h) and operates at an efficiency of 33% based on LHV. Assume that a power generation end output of 25 kW is output.

When the engine cooling water JW at 60 ° C. and 1400 kg / h is supplied to the engine 2, the engine cooling water JW is heated to 82 ° C. and discharged. That is, 38 kW of exhaust heat is discharged from the engine 2 as sensible heat of the engine coolant JW, and this exhaust heat is recovered by the exhaust heat recovery heat exchanger 25 for heating the heat source water HW. It will be.
On the other hand, the exhaust gas E at 150 ° C. and 123 Nm ³ / h is discharged from the engine 2 to the exhaust gas passage 3, and the exhaust gas E contains 12.3 kg / h (12.4 vol%) of moisture.

[During normal operation]
Next, the heat balance when the frost prevention control is not executed (during normal operation) will be described.
In the latent heat recovery heat exchanger 31, a feed water SW of 10 ° C. and 1000 kg / h is supplied from the water receiving tank 50, and the latent heat of the exhaust gas E flowing through the exhaust gas passage 3 is recovered by heat exchange with the feed water SW, The feed water SW is preheated to 20 ° C. That is, in the latent heat recovery heat exchanger 31, 12 kW heat including the latent heat of the exhaust gas E is recovered for preheating the feed water SW.
Further, in this latent heat recovery heat exchanger 31, a relatively large amount of condensate CW is generated at 9.8 kg / h, so that many corrosive gases contained in the exhaust gas E are well absorbed and removed by the condensate CW. It is thought that it is done.

  On the other hand, in the compression heat pump circuit 1, exhaust gas of 28 ° C. is supplied as a heat source in the evaporator 13, and the water supply SW of 5 ° C. and 50 kg / h is heated to 85 ° C. in the condenser 11. That is, in the compression heat pump circuit 1, a heat output of 4.7 kW is generated, and a high COP of 3.6 is realized regardless of the outside air temperature.

[When frost prevention control is executed]
Next, the heat balance when performing frost prevention control will be described.
In the latent heat recovery heat exchanger 31, the opening degree of the adjustment valve 34 is reduced compared to that during the normal operation, and a feed water SW of 10 ° C. and 740 kg / h is supplied from the water receiving tank 50. The latent heat of the exhaust gas E flowing through the exhaust gas passage 3 is recovered by exchange, and the feed water SW is preheated to 20 ° C. That is, in the latent heat recovery heat exchanger 31, 8.8 kW of heat including the latent heat of the exhaust gas E is recovered for preheating the feed water SW.
Further, in this latent heat recovery heat exchanger 31, 5.5 kg / h of condensed water CW is generated, which is less than that in the normal operation, and at least a part of the corrosive gas contained in the exhaust gas E is converted into the condensed water CW. It is thought that it is absorbed and removed.

On the other hand, in the compression heat pump circuit 1, a so-called defrost operation is performed in which the evaporator 13 is supplied with a relatively high temperature exhaust gas of 40 ° C. as a heat source, and the frost adhering to the evaporator 13 is melted well. Is considered that the corrosive gas contained in the exhaust gas E is absorbed and removed by the water generated by the melting of the frost.
In the condenser 11, the feed water SW of 5 ° C. and 50 kg / h is heated to 85 ° C. That is, in the compression heat pump circuit 1, a heat output of 4.7 kW is generated and a COP as high as 3.6 is realized.

  In addition, the overall heat efficiency of the heat source system 100 described above is 104% during the normal operation and 99% during the execution of the frost prevention control, based on LHV, and a system with high energy saving is realized. It can be said that.

[Another embodiment]
(1) In the above embodiment, the configuration in which the heat source system 100 according to the present invention is installed in the heat supply system that supplies heat to each residence 101 in the apartment house 105 has been described. 100 may be installed in another form.

(2) In the above embodiment, the latent heat recovery state adjusting means capable of adjusting the latent heat recovery state by the latent heat recovery heat exchanger 31 is used to adjust the supply valve SW supply amount to the latent heat recovery heat exchanger 31. However, this latent heat recovery state adjusting means is separately provided with a latent heat recovery heat exchanger such as a bypass valve that can adjust the amount of exhaust gas E that bypasses the latent heat recovery heat exchanger 31 in the exhaust gas passage 3. You may comprise by the means etc. which adjust the distribution | circulation amount of the waste gas E in 31.

(3) In the above embodiment, when the compressor 10 is driven by the engine 2, the generator 20 is driven by the shaft output of the engine 2 to generate electric power, and the electric motor 15 is driven by the electric power generated by the generator 20. Although the compressor 10 is driven by the electric motor 15, a separate configuration may be employed such that the compressor 10 is directly driven by the shaft output of the engine 2.

(4) In the above embodiment, only the exhaust gas E exhausted from the engine 2 is supplied to the evaporator 13 of the compression heat pump circuit 1 through the exhaust gas passage 3, but, for example, latent heat recovery heat exchange is performed. Another gas may be supplied to the evaporator 13 in addition to the exhaust gas E, such as mixing outside air with the exhaust gas E after passing through the vessel 31 and supplying the mixed gas to the evaporator 13.

(5) In the above embodiment, the engine 2 that outputs the driving force of the compressor 10 is provided as a combustion apparatus that burns fuel and discharges the exhaust gas to the exhaust gas passage 3. A combustion device of another form may be provided, or the combustion device may not output the driving force of the compressor.

  The heat source system according to the present invention includes an exhaust gas discharged from a combustion device that burns fuel, such as an engine that outputs a driving force of a compressor of a compression heat pump circuit, through an exhaust gas passage, and an evaporator of the compression heat pump circuit. This is a heat source system that supplies heat as a heat source, and is effective as being capable of preventing corrosion of the constituent materials of the evaporator by corrosive gas contained in the exhaust gas with a low cost and simple configuration while maintaining high efficiency. Is available.

Schematic configuration diagram of heat source system Conceptual diagram of heat supply system

Explanation of symbols

1: Compression heat pump circuit 2: Engine (combustion device)
3: Exhaust gas path 10: Compressor 11: Condenser 12: Expansion valve 13: Evaporator 15: Electric motor 20: Generator 25: Waste heat recovery heat exchanger 32: Condensate recovery unit 34: Adjustment valve (latent heat recovery state adjustment means)
35: Temperature sensor 36: NOx sensor 38: Relief valve (over-pressurization preventing means)
50: Water receiving tank 60: Hot water storage tank 70: Control device 71: Frosting state determination means 72: Corrosive gas state determination means 73: Control means 100: Heat source system 102: Circulation pipe 102g: Outward path 102r: Return path 103: Water supply Piping CW: Condensed water HW: Heat source water SW: Feed water X: Refrigerant

Claims (6)

A compressor that compresses the refrigerant, a condenser that dissipates heat from the refrigerant, an expansion valve that expands the refrigerant, and an evaporator that absorbs heat to the refrigerant, and a compression heat pump circuit that circulates in this order.
A heat source system comprising an exhaust gas path for supplying exhaust gas discharged from a combustion device for burning fuel as a heat source of the evaporator,
A latent heat recovery heat exchanger that preheats feed water by latent heat of water vapor contained in the exhaust gas flowing between the combustion device and the evaporator in the exhaust gas path, and condensate water generated by the latent heat recovery heat exchanger are recovered. A condensate recovery unit , provided between the combustion device and the evaporator in the exhaust gas path,
The heat source system configured such that the exhaust gas flowing through the exhaust gas passage is guided to the evaporator after the corrosive gas is absorbed by the condensed water recovered by the condensed water recovery unit . A latent heat recovery state adjusting means capable of adjusting a latent heat recovery state by the latent heat recovery heat exchanger;
Frost state determination means for determining a frost state in the evaporator;
2. The heat source system according to claim 1, further comprising a control unit that executes frost prevention control for controlling the latent heat recovery state adjustment unit based on a determination result of the frosting state determination unit. A latent heat recovery state adjusting means capable of adjusting a latent heat recovery state by the latent heat recovery heat exchanger;
Corrosive gas state determining means for determining a corrosive gas state in the exhaust gas flowing downstream of the latent heat recovery heat exchanger in the exhaust gas path;
3. The heat source system according to claim 1, further comprising a control unit that executes a corrosion prevention control that controls the latent heat recovery state adjustment unit based on a determination result of the corrosive gas state determination unit. An exhaust heat recovery heat exchanger for heating hot water with the exhaust heat of the combustion device;
A circulation pipe that circulates hot water heated by the exhaust heat recovery heat exchanger as heat source water in a form that can be taken out by the consumer for the consumer,
The condenser is configured to heat feed water by heat dissipation of the refrigerant;
The water supply heated by the condenser is replenished to the return path side of the circulation pipe, and the water preheated by the latent heat recovery heat exchanger is replenished to the return path side of the circulation pipe. Item 4. The heat source system according to any one of Items 1 to 3. A water receiving tank for storing water preheated by the latent heat recovery heat exchanger;
The water supply stored in the water receiving tank is configured to replenish the return path side of the circulation pipe,
5. The heat source system according to claim 4, further comprising an overpressure prevention means for preventing the occurrence of overpressure in the circulation pipe by returning the heat source water of the circulation pipe to the water receiving tank. The combustion device is an engine that outputs a driving force of the compressor;
A generator driven by the engine to generate electric power;
The heat source system as described in any one of Claims 1-5 provided with the electric motor which act | operates with the electric power which the said generator generate | occur | produced, and drives the said compressor.

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