KR101587256B1 - A combined heat and power system with a double layered reservoir - Google Patents

Abstract

The present invention relates to a combined heat and power system with a complex reservoir including a heat storage tank and a hot water tank covering the heat storage tank, capable of coping with variations in a hot water load and a power load over time through various operation methods by providing the heat storage tank as a different energy source, and minimizing heat loss of the heat storage tank and reducing an installation space through the complex reservoir. The combined heat and power system comprises a first circulation pipe allowing a first working fluid to flow therein and a first circulation pump installed in the first circulation pipe to circulate the first working fluid, a heating device heating the first working fluid flowing in the first circulation pipe to convert the first working fluid into a high temperature and high pressure state, a heat storage tank storing a heat storage material storing thermal energy through heat exchange with the first working fluid in the high temperature and high pressure state, an expander converting expansive force of the first working fluid in the high temperature and high pressure state which has passed through the heat storage tank into rotational force, a power generator producing electric energy using the expander as a prime mover, a heat-exchanger converting the first working fluid in a low temperature and low pressure gas state discharged from the expander into a low temperature and low pressure liquid state through heat-exchange, a second circulation pipe allowing a second working fluid to flow therein and overlapping a first circulation pipe in the heat-exchanger to cause heat-exchange between the first working fluid and the second working fluid, a second circulation pump installed in the second circulation pipe to circulate the second working fluid, and a hot water tank covering the heat storage tank to prevent the heat storage tank from being exposed to the outside to minimize loss of thermal energy stored in a heat storage material and heating hot water stored therein through heat-exchange with the second working fluid which has absorbed thermal energy through heat-exchange with the first working fluid in the heat-exchanger.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cogeneration system having a composite water tank,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cogeneration system, and more particularly, to a cogeneration system having a composite water tank including a heat storage tank and a hot water tank surrounding the storage tank.

The heating system of apartment complexes such as apartment complexes has central heating, district heating, and individual heating depending on the way of supplying calories to a heating place.

The central heating is a method of heating a boiler or other heat source in a basement or a separate place from which a heating medium such as steam, hot water or hot air is supplied to each home.

Local heating is a type of heating system that supplies hot water produced in a large scale heat production facility such as a cogeneration power plant and a garbage incinerator to an apartment complex in a certain area through pipelines buried underground, instead of having individual heat production facilities in apartment complexes .

Individual heating is a method in which individual heaters are used in each house to heat them individually. Individual heating can be adjusted to allow each family to heat at the desired time, and it has the advantage of paying only as much as it uses. However, since the individual heating uses a small boiler, it has a disadvantage that the heat efficiency is lowered and the fuel cost is higher than the district heating.

To solve these drawbacks, a combined heat and power system with high energy efficiency has been proposed. A cogeneration system is a total energy system that simultaneously produces power and heat from a single energy source. In general, the high temperature is used as a power source to generate electricity and the low temperature is used as a heat source.

1 is a conceptual diagram briefly showing a conventional cogeneration system. 1, after heating a working fluid in a boiler 1, an inflator 2 connected to an alternator 4 is operated using a working fluid in a gaseous state at a high temperature and a high pressure to produce electricity The hot water stored in the hot water tank 3 is heated by a heat exchange method using the low-temperature and low-pressure working fluid discharged from the expander 2.

Patent Registration No. 10-1389650 Patent Registration No. 10-1264249 Patent Registration No. 10-1249445 Japanese Patent Application Laid-Open No. 10-2014-0029262

In the case of a general household, the time zone in which the hot water load including the heating load is large and the time zone in which the power load is large do not coincide with each other. That is, although the power load is large in the daytime, the heating load is very small, and there is little power load at night and early morning, but the heating load is very large. In the conventional cogeneration system, since the power and heat are generated simultaneously as one energy source of the boiler, there is a problem that the heat is excessively produced in the daytime and the electric power is excessively produced in the night and early morning hours.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cogeneration system having another energy storage device called a heat storage tank.

It is another object of the present invention to provide a cogeneration system having a composite water tank in which a hot water tank surrounds a heat storage tank, thereby minimizing heat loss of the heat storage tank.

According to an aspect of the present invention, there is provided a cogeneration system including a first circulation pipe through which a first working fluid flows, a first circulation pump installed in the first circulation pipe and circulating the first working fluid, A heat storage device for storing the heat storage material for storing heat energy through heat exchange between the first working fluid flowing in the circulation pipe and the first working fluid in the high temperature and high pressure state, An expander for converting the expansion force of the first working fluid in a gaseous state of high temperature and high pressure that has passed through the heat storage tank into a rotary force; a generator for producing electric energy using the expander as a prime mover; A heat exchanger for converting the first working fluid in a gaseous state of a low pressure into a liquid state of a low temperature and a low pressure and a second working fluid, And a second circulation pump installed in the second circulation pipe and circulating the second working fluid, wherein the second circulation pipe overlaps the first circulation pipe in the heat exchanger so that heat exchange occurs between the second circulation pipe and the second working fluid, The second working fluid absorbing heat energy through heat exchange with the first working fluid in the heat exchanger, and the second working fluid absorbing the heat energy by heat exchange with the first working fluid in the heat exchanger to minimize the loss of heat energy stored in the heat- And a hot water tank configured to heat the hot water stored therein through heat exchange between the hot water tank and the hot water tank.

The cogeneration system may further include a heat insulating layer disposed between the hot water tank and the heat storage tank to restrict heat exchange between the hot water tank and the heat storage tank.

Further, it is preferable to further include an electric heater for heating the heat storage material in the heat storage tank. The electric heater can be operated by electricity generated by the generator at a time when power load is low.

The first working fluid discharged from the heat storage tank may be selectively supplied to the bypass pipe through the bypass pipe bypassing the inflator, and a three-way valve connecting the first circulation pipe and the bypass pipe. And the three-way valve is controlled to bypass the inflator through the bypass piping.

The cogeneration system described above is configured to bypass the hot water tank to supply a second circulating fluid directly to the heating load, and the hot water bypass pipe connected to the second circulation pipe and the second circulation pipe are connected to the hot water tank Or a plurality of three-way valves for controlling the flow of the second circulating fluid to selectively connect to the heating load.

The cogeneration system having the complex water tank according to the present invention has an advantage of being able to cope with fluctuations of the hot water load and the electric power load over time through various operation methods because it has another energy source called a heat storage tank. Also, the composite water tank has a structure in which the hot water tank encloses the heat storage tank, thereby minimizing the heat loss of the heat storage tank and reducing the installation space.

1 is a conceptual diagram briefly showing a conventional cogeneration system.
2 is a conceptual diagram briefly showing an embodiment of a cogeneration system according to the present invention.
3 is an incision oblique view of the composite water tank shown in Fig.

Hereinafter, preferred embodiments of the cogeneration system according to the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

2 is a conceptual diagram briefly showing an embodiment of a cogeneration system according to the present invention. 2, an embodiment of the cogeneration system according to the present invention includes a first circulation pipe 10 and a first circulation pump 11 through which a first working fluid flows, a heating device (not shown) for heating a first working fluid An expansion tank 30, a generator 39 and a heat exchanger 40. The combined water tank 50 includes a water tank 20, a heat storage tank 52 and a hot water tank 58. The second circulation pipe (60) and the second circulation pump (61) overlap the first circulation pipe (10) in the heat exchanger and through which the second working fluid flows.

The first working fluid plays a role of absorbing and releasing heat energy by temperature and phase change. The first working fluid transfers heat energy while using the first circulation pipe (10) connecting the respective components of the cogeneration system to each other.

As the first working fluid in the present invention, it is preferable to use methanol, ethanol, HFC refrigerant or HCFC refrigerant. In the cogeneration system according to the present invention, since the heat exchanger 40 functions as a condenser, the condensation temperature of the first working fluid must be higher than the temperature of the water as the second working fluid flowing into the heat exchanger 40, The first working fluid condenses through the heat exchange in the first working fluid.

The circulation pipe (10) is provided with a circulation pump (11) for circulating the working fluid. Since the circulating pump 11 can only pump liquid, the working fluid must be condensed after expansion.

The heating device 20 may be a device for directly heating the first circulation pipe 10. At this time, the first circulation pipe 10 at the heated position may have a fin in order to improve heat transfer efficiency.

Further, the heating device 20 may be a boiler including a tank in which water or oil is stored, and a heating section for heating the tank. The heating unit is disposed under the tank and can heat the tank by burning fuel such as oil or gas supplied to the heating unit. The first circulation pipe (10) passes through the inside of the tank of the heating device (20). The first working fluid that has passed through the heating device 20 absorbs heat from the water or oil stored in the tank inside the boiler and is converted into a gas of high temperature and high pressure.

The first working fluid in a gaseous form at a high temperature and a high pressure flows into the complex water tank (50). 3, the composite water tank 50 includes a hot water tank 58 surrounding the thermal storage tank 52 and the thermal storage tank 52, a heat insulating layer 56 disposed between the thermal storage tank 52 and the hot water tank 58, . The heat storage tank 52 is filled with a heat storage material capable of heat storage in a temperature range of approximately 100 to 200 ° C. In addition, the heat storage tank 52 may be provided with an electric heater 54 for heating the heat storage material. As the heat storage material, for example, oils having a high boiling point can be used. The heat storage tank 52 is provided with a pipe 53 in the form of a coil for heat exchange and the first circulation pipe 10 is connected to the pipe 53. At the beginning of the operation, the thermal energy of the first working fluid is transferred to the heat storage material of the heat storage tank 52, so that the inflator 30 may not operate. However, once the heat storage tank 52 is sufficiently heated, the heat energy of the first working fluid is not lost in the heat storage tank 52, so that the first working fluid passing through the heat storage tank 52 can maintain the high temperature and high pressure state. In order to prevent the use of heat energy for heating the storage tank 52 in the early stage of operation, the thermal storage tank 52 may be heated in advance by operating the electric heater using night-time electricity. This night-time electricity may be electricity produced by the generator 39 of the cogeneration system. The cogeneration system must be operated at night because the hot water load is large. However, since the power load is not large, the remaining power can be used for heating the storage tank 52. A hot water load means a load that requires hot water including a heating load. The heat storage tank 52 also serves as a kind of buffer that keeps the temperature and the pressure of the first working fluid flowing into the inflator 30 constant. It also functions as an auxiliary heat source for applying thermal energy to the first working fluid in place of the heating device 20. [ The temperature of the first working fluid passing through the heating device 20 may be changed according to the temperature change of the second working fluid due to the variation of the usage amount of the hot water and the thermal energy applied by the heating device 20 may not always be constant . The heat storage tank 52 can serve to compensate for this difference.

Referring again to FIG. The first working fluid in the high temperature and high pressure state that has passed through the heat storage tank 52 flows into the inflator 30 and rotates the rotor (not shown) of the inflator 30. The expander 30 may be a screw expander or a scroll expander. When the inflator 30 is rotated, power is generated in the rotary generator 39 connected to the inflator 30. As described above, the heat storage tank 52 can compensate for the change in the thermal energy of the first working fluid flowing into the inflator 30, so that the inflator 30 can rotate the generator 39 more stably . The working fluid, which consumes thermal energy in the process of rotating the inflator 30, is discharged from the inflator 30 in the form of a low-temperature and low-pressure gas.

In addition, the cogeneration system having the composite water tank according to the present embodiment may further include a bypass pipe 12 bypassing the inflator 30. A three-way valve (13a, 13b) is provided at a position where the bypass pipe (12) and the first circulation pipe (10) meet. The first working fluid passes through the thermal storage tank 52 and bypasses the inflator 30 through the bypass pipe 12. In the case where the heat storage tank 52 needs to be heated, . In this case, the high-temperature energy of the first working fluid is transmitted to the heat storage tank 52, and the low-temperature energy is transmitted to the hot water tank 58.

The first working fluid discharged from the expander (30) exchanges heat with the second working fluid in the heat exchanger (40) to transfer the heat energy to the second working fluid while causing a phase change to the low temperature and low pressure liquid form.

The first working fluid having passed through the heat exchanger (40) is again changed to a high temperature and high pressure state through the heating device (20).

The second working fluid absorbing the thermal energy of the first working fluid in the heat exchanger 40 flows along the second circulation pipe 10 connecting the heat exchanger 40 and the hot water tank 58 of the complex water tank 50 Move. That is, the second working fluid absorbs the heat of the low-temperature portion of the first working fluid in the heat exchanger 40 and transmits heat to the hot water stored in the hot water tank 58 of the composite water tank 50. In this embodiment, it is preferable to use water as the second working fluid.

The second working fluid absorbing the heat in the heat exchanger 40 is installed inside the hot water tank 58 of the composite water tank 50 and is connected to the second circulation pipe 60 in the form of a spiral coil pipe 59 And transfers the heat to the hot water stored in the hot water tank 58.

The hot water tank 58 is connected to various loads using hot water. For example, as shown in FIG. 2, it may be connected to the heating load 70. As described above, in the present invention, the composite water tank is a type in which the hot water tank 58 surrounds the heat storage tank 52. The structure of this complex water tank is advantageous in that heat loss of the heat storage tank 52 can be minimized and unavoidable heat loss in the heat storage tank 52 is transferred to the hot water tank 58 and utilized. Even when the heat storage tank 52 is surrounded by the heat insulating layer 56, when the heat storage tank 52 is exposed to the outside, the difference in temperature between the heat storage tank 52 and the outside temperature is large, Can be relatively large. In the case of the present invention, since the thermal storage tank 52 is surrounded by the hot water tank 58 filled with hot water, which is much higher than the outside temperature, the heat loss is relatively small. In addition, since the heat lost in the heat storage tank 52 is not discharged to the outside, but is transferred to the hot water tank 58 and utilized, the actual heat loss is less.

The present embodiment further includes a hot water bypass pipe for directly connecting the second circulation pipe 60 to the heating load 70 instead of the hot water tank 58. The hot water tank bypass pipe includes an upstream side hot water tank bypass pipe (81) and a downstream side hot water tank bypass pipe (82). Three-way valves 83a and 83b are provided at positions where the upstream side hot water tank bypass pipe 81 and the second circulation pipe 60 meet with each other and where the hot water tank bypass pipe 81 and the heating load 70 meet with each other, Respectively. The three-way valves 84a and 84b are provided at positions where the downstream side hot water tank bypass pipe 82 and the second circulation pipe 60 meet with each other and where the hot water bypass pipe 82 and the heating load 70 meet with each other, 84b. Way valves 83a, 83b, 84a and 84b so as to directly supply the second working fluid to the heating load 70 at the evening or early morning hours when a lot of heating is required and to supply the second working fluid to the hot water tank 58 To the second working fluid.

An example of the operation of the cogeneration system having the aforementioned complex water tank will be described below. The cogeneration system having the composite water tank according to the present invention can be driven in various ways, and the following operation method is only one example.

First, the heating apparatus 20 is operated in the morning time in which there is little hot water load and power load, and heat energy is accumulated in the heat storage material of the heat storage tank 52. At this time, the first working fluid discharged from the thermal storage tank (52) through the bypass pipe (12) connecting the upstream side of the inflator (30) and the downstream side of the inflator (30) Way valves 13a and 13b so as to be flown back into the two-way valves 20a and 20b. This is because the heat loss in the heat storage tank 52 makes it difficult for the expander 30 to operate. However, when the preheating of the inflator 30 is required as in the winter, the first working fluid passing through the heat storage tank 52 may pass through the inflator 30. And the remaining waste heat is transferred from the heat exchanger 40 to the second working fluid. The thermal energy transferred to the second working fluid is stored in the hot water tank 58 of the complex water tank 50.

The first working fluid having a high temperature and a high pressure passing through the storage tank 52 does not pass through the bypass pipe 12 but flows through the inflator 30 to the power Is produced. And the waste heat remaining after producing electric power is transferred from the heat exchanger 40 to the second working fluid. The thermal energy transferred to the second working fluid is stored in the hot water tank 58 of the complex water tank 50. The stored heat energy is used in the evenings or early morning hours when the hot water load is large. At this time, the thermal energy for electric production may be supplied through the heating device 20, or the thermal energy stored in the thermal storage tank 52 may be used. That is, it is also possible to stop the operation of the heating device 20 and to heat the first working fluid through the thermal energy stored in the heat storage tank 52.

The second working fluid is directly supplied to the heating load at the nighttime and the early morning time when the hot water load is large and the electric power load is small and the electricity remaining in the produced electricity can be utilized as an application for operating the electrothermal heater 54 of the heat storage tank 52 have. Further, the first working fluid may pass through the bypass pipe 12 so that the energy of the high temperature part may store heat energy in the heat storage tank 52, and the energy of the low temperature part may be directly supplied to the heating load.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: first circulation piping 11: first circulation pump
12: Bypass piping 20: Heating device
30: inflator 39: generator
40: heat exchanger 50: complex water tank
52: heat storage tank 54: electrothermal heater
56: insulation layer 58: hot water tank
60: second circulation pipe 61: second circulation pump
70: Heating load
81: Upstream side hot water tank bypass piping
82: Downstream hot water tank bypass pipe

Claims (6)

A first circulation pipe through which the first working fluid flows and a first circulation pump installed in the first circulation pipe for circulating the first working fluid,
A heating device for heating the first working fluid flowing through the first circulation pipe to convert the first working fluid to a high-temperature and high-pressure gas state,
A heat storage tank for storing a heat storage material for storing heat energy through heat exchange with the first working fluid in a high temperature and high pressure state,
An expander for converting the expansion force of the first working fluid in the high-temperature and high-pressure state that has passed through the thermal storage tank into a rotary force; a generator for generating electric energy using the expander as a prime mover;
A heat exchanger for converting the first working fluid in a low-temperature and low-pressure gaseous state discharged from the inflator through heat exchange into a low-temperature and low-pressure liquid state,
A second circulation pipe through which the second working fluid flows and which causes heat exchange between the first working fluid and the second working fluid to overlap with the first circulation pipe in the heat exchanger and a second circulation pipe provided in the second circulation pipe, A second circulation pump for circulating the second working fluid,
The second working fluid absorbing heat energy through heat exchange with the first working fluid in the heat exchanger, and the second working fluid absorbing the heat energy by heat exchange with the first working fluid in the heat exchanger to minimize the loss of heat energy stored in the heat- And a hot water tank configured to heat the hot water stored therein through heat exchange of the hot water tank. The method according to claim 1,
And a heat insulating layer disposed between the hot water tank and the heat storage tank to restrict heat exchange between the hot water tank and the heat storage tank. The method according to claim 1,
And a heat transfer heater for heating the heat storage material in the heat storage tank. The method of claim 3,
Wherein the electric heater is operated by electric power generated by the generator at a time when power load is low. The method according to claim 1,
Further comprising a bypass pipe bypassing the inflator, and a three-way valve connecting the first circulation pipe and the bypass pipe,
Wherein the three-way valve is controlled such that the first working fluid discharged from the heat storage tank selectively bypasses the inflator through the bypass pipeline during a time when the power load is low. The method according to claim 1,
A hot water bypass pipe connected to the second circulation pipe and the second circulation pipe connected to the hot water tank or the heating load so as to bypass the hot water tank to supply a second circulating fluid directly to the heating load, Further comprising a plurality of three-way valves for controlling the flow of the second circulating fluid.

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