KR20150043830A - Apparatus for Withdrawing the Exhaust Heat of a Boiler using Thermo-syphon - Google Patents

Abstract

An apparatus for recovering exhaust heat of a boiler using thermo-siphon is provided. The apparatus for recovering exhaust heat of a boiler using thermo-siphon comprises: a control valve which distributes high temperature and pressure coolant to a first branch line or a second branch line, wherein the coolant is discharged from a four-way valve converting a movement direction of coolant discharged from a compressor compressing the coolant; a first heat exchanger which releases heat so that the high temperature and pressure coolant selectively supplied through the first branch line is heat-exchanged with supplied water supplied from a water supply tank storing the predetermined amount of water and is heated; a second heat exchanger which releases heat so that the high temperature and pressure coolant selectively supplied through the second branch line is heat-exchanged with external air; a third heat exchanger which is connected with the third branch line having a first expanding valve expanding the coolant discharged from the first heat exchanger and is connected with the fourth branch line having a second expanding valve expanding the coolant discharged from the second heat exchanger so that the expanded coolant absorbs heat from the external air and is evaporated, and discharges the evaporated coolant to the compressor; and a defrost unit which includes an exhaust pipe discharging and guiding exhaust gas so that the exhaust gas discharged from the boiler is heat-exchanged with the third heat-exchanger and provides a heat source to remove frozen moisture generated when coolant is evaporated in the third heat exchanger.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus for recovering exhaust heat of a boiler using a thermal siphon,

The present invention relates to an apparatus for recovering exhaust heat of a boiler, and more particularly to an apparatus for recovering exhaust heat of a high temperature exhausted to the outside during a running operation of a boiler and a heat source of a working fluid evaporated in the recovered exhaust heat, The heat exchange efficiency of the heat pump is increased by recycling the heat pump as a heat source, and there is no need for a complicated defrosting system in which a defrost heater is additionally provided or the refrigerant circulation cycle is reversely operated, thereby fundamentally preventing frost formation in the evaporative heat exchanger And more particularly, to an apparatus for recovering exhaust heat of a boiler using a thermal siphon.

Generally, a system for recovering the waste heat of a high temperature exhaust gas discharged from a boiler installed for heating a building or a home uses a direct contact type condensation heat recovery apparatus for recovering waste heat of a corrosive high temperature boiler exhaust gas.

Here, in the case of a direct contact type condensing heat exchanger for recovering the waste heat of the boiler exhaust gas, the boiler exhaust gas is directly contacted with water while passing through the heat exchanger, and the heat is transferred. In the case of the water fluidized bed heat exchanger, The arrangement of the heat transfer tubes is located in the fluidized bed of water, so that the problem of low temperature corrosion can be solved.

Korean Patent Laid-Open Publication No. 10-2012-0112902 (Oct. 12, 2012) discloses a method in which a feed water supplied to a boiler stored in a boiler feed tank is firstly heated using a direct contact type condensate heat exchanger for recovering waste heat of a boiler exhaust gas, There is disclosed a waste heat recovery system for a boiler using a heat pump which firstly heats boiler feed water heated by a contact type condensing heat exchanger by a heat pump device once more by supplying heat to the boiler.

The heat pump employed in such a boiler includes a compressor for compressing the refrigerant, a four-way valve for switching the circulation direction of the refrigerant, a condenser for discharging the heat of the high temperature and high pressure refrigerant, and an expansion valve for expanding the refrigerant discharged from the condenser, (High pressure, low pressure) absorbs the surrounding heat source and uses the absorbed heat source as energy for raising the temperature of the air or the water, and is mainly used for the air heat, the geothermal heat, the waste heat, The heat source having a certain temperature such as river heat and seawater heat is taken as it is, or the temperature is taken through the heat exchanger and utilized as energy.

However, the heat pump integrated with the boiler to implement the new hydroid boiler system increases the heating capacity required when the outdoor temperature is lowered in the winter season, but the heating capacity of the heat pump is reduced, The efficiency is lowered. When the outside air temperature is lowered, the defrosting cycle is frequently repeated by promoting the impregnation on the coil of the evaporator installed outside, thereby reducing the heating capacity and the COP (Coefficient of performance) Which increases the possibility of breakage of the heat pump, it is the biggest problem to activate the heat pump for home use.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an evaporative heat exchanger which recovers hot exhaust gas exhausted to the outside during a running operation of a boiler, The heat exchange efficiency of the heat pump is increased by recycling the heat pump as a heat source, and there is no need for a complicated defrosting system in which a defrost heater is additionally provided or the refrigerant circulation cycle is reversely operated, thereby fundamentally preventing frost formation in the evaporative heat exchanger And to provide a device for recovering exhaust heat of a boiler using a thermal siphon which can delay or delay the operation of the boiler.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

In order to achieve the above object, the present invention provides an apparatus for recovering exhaust heat of an exhaust gas discharged from a boiler, the apparatus comprising: A control valve for branching the high-temperature and high-pressure refrigerant to the first branch line or the second branch line; A first heat exchanger to heat and cool the high-temperature and high-pressure refrigerant selectively supplied through the first branch line to heat-exchange with heat supplied from the outside; A second heat exchanger for heating and discharging the high-temperature high-pressure refrigerant selectively supplied through the second branch line to heat exchange with the outside air; And a fourth branch line connected to a third branch line having a first expansion valve for expanding the refrigerant discharged from the first heat exchanger and having a second expansion valve for expanding the refrigerant discharged from the second heat exchanger A third heat exchanger for expanding the refrigerant to absorb heat from the outside air to be evaporated, and discharging the evaporated refrigerant to the compressor; And a thermal siphon which is evaporated during heat exchange with the exhaust gas discharged from the boiler and is connected to a circulation line in which a working fluid that is condensed when heat exchange with the third exchanger is circulated in one direction is provided in an exhaust pipe through which the exhaust gas is discharged An upper portion for providing a heat source for preventing condensation of water generated during evaporation of the refrigerant in the third heat exchanger; And an exhaust heat recovery device for the boiler using the thermal siphon.

Preferably, the first heat exchanger is connected to a boiler, a floor heating tube, or a hot water tank via a hot water line through a water supply line to which water is supplied from the outside.

More preferably, the hot water line includes a first branching hot water line connected to the boiler at one end via three sides to selectively supply hot water to the boiler or the bottom tube for heating, The second branch hot water line.

More preferably, the hot water line is connected to the hot water tank so as to store the hot water through the other three sides provided in the middle of the length.

Preferably, the thermal siphon is formed of a hollow cylindrical tube having an inner circumferential surface on an outer surface of a discharge pipe for discharging combustion exhaust gas from the boiler and filled with a predetermined amount of working fluid.

More preferably, the upper end of the hollow cylindrical tubular body is connected to one end of a circulating line through which the working fluid on the evaporated gas flows, and the upper end of the hollow cylindrical tubular body is connected to the other end of the circulating line through which the condensed liquid working fluid flows do.

Preferably, the thermal siphon is disposed at a position relatively lower than the installation position of the third heat exchanger so that the circulating supply of the working fluid, which is phase-changed from the third heat exchanger to the liquid phase, is smoothly performed.

Preferably, an auxiliary heat exchanger is disposed at a rear end of the third heat exchanger for exchanging heat between the working fluid recirculated to the thermal siphon and the refrigerant supplied to the interior of the third heat exchanger to increase the temperature of the refrigerant.

The present invention as described above has the following effects.

(1) The working fluid evaporated by the exhaust gas of the boiler is circulated and supplied to the circulation line connected to the low-temperature and low-pressure refrigerant so as to pass through the evaporative third heat exchanger where the refrigerant absorbs heat from the outside and is heat-exchanged, The third heat exchanger is provided with a heat absorbing source in the process of heat exchange with the third heat exchanger to thereby improve the thermal efficiency during driving of the heat pump.

(2) Since the temperature of the outside air sucked into the third heat exchanger, which is the evaporation type heat exchanger constituting the heat pump, can be artificially raised by the working fluid evaporated in the exhaust heat of the exhaust gas, It is possible to fundamentally prevent or delay the implantation due to moisture condensation in the evaporative heat exchanger without the need for an additional defrost system such as a defrost heater, thereby improving the operating efficiency of the boiler system using the heat pump.

FIG. 1 is a general view showing a state in which refrigerant is operated through a first heat exchanger and a third heat exchanger of a heat pump in an exhaust heat recovery apparatus of a boiler using a thermal siphon according to a preferred embodiment of the present invention.
FIG. 2 is a general view showing a state where refrigerant is operated through a second heat exchanger and a third heat exchanger of a heat pump in an exhaust heat recovery apparatus of a boiler using a thermal siphon according to a preferred embodiment of the present invention.
3 is a state in which a circulation line employed in an apparatus for recovering exhaust heat of a boiler using a thermal siphon according to a preferred embodiment of the present invention is installed in a third heat exchanger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings.

In addition, in the entire specification, when a part is referred to as being 'connected' to another part, it may be referred to as 'indirectly connected' not only with 'directly connected' . Also, to include an element does not exclude other elements unless specifically stated otherwise, but may also include other elements.

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

As shown in FIGS. 1 to 3, an exhaust heat recovery apparatus 100 for a boiler using a thermal siphon according to a preferred embodiment of the present invention includes an exhaust gas heat exchanger The first heat exchanger 110, the second heat exchanger 110, the second heat exchanger 110, the second heat exchanger 110, and the second heat exchanger 110. The first heat exchanger 110, the second heat exchanger 110, 120, a third heat exchanger 130, and a top 140.

The control side 101 includes a first refrigerant line 151 connected to the four-way switching valve 103 for switching the traveling direction of the refrigerant discharged from the compressor 102 compressing the refrigerant to the forward direction or the reverse direction, And the first and second refrigerant branch lines (111, 121) connected to the two heat exchangers (110, 120).

In this case, between the compressor 102 and the four-way switching valve 103, a filter member (not shown) is inserted in the middle of the length of the second refrigerant line 152 so as to remove foreign substances contained in the refrigerant of high temperature and high pressure discharged from the compressor to the four- And a storage tank 102b may be optionally provided in the middle of the third refrigerant line 153 so as to temporarily store low-temperature low-pressure refrigerant discharged from the four-way switching valve 103 to the compressor 102 side have.

The control side 101 is connected to a first branch line 103 for guiding and supplying the high-temperature and high-pressure refrigerant discharged from the four-way switching valve 103 through the first refrigerant line 151 to the first heat exchanger 110 side. And a second branch line 121 for guiding and supplying the high-temperature and high-pressure refrigerant to the second heat exchanger 120 side. The control unit 110 controls the high-temperature high-pressure The first branch line 111 or the second branch line 121 and performs branching guidance.

The first heat exchanger 110 exchanges heat with water supplied from an external supply source or a water supply tank through which a predetermined amount of water is stored, It is a condensed heat exchanger that emits heat to heat.

The hot water heated to a predetermined temperature while passing through the inside of the first heat exchanger 110 is supplied to the hot water line 2b through the first heat exchanger 110, Or may be selectively supplied to the bottom heating tube 3 side or stored in the hot water tank 2.

 The hot water line 2b is connected to the boiler 1 via a three-way side 4a so as to selectively supply hot water to the boiler or the floor heating tube 3, And a second branch hot water line 3a connected at one end to the bottom heating tube 3, respectively.

In the middle of the length of the hot water line 2b, a hot water tank 2 for storing a certain amount of hot water through the other three sides 4 may be provided.

The water supply line 2a is provided with a pump member 5 for pumping and supplying water stored in the water supply tank 2 to the first heat exchanger 110. The hot water line 2b is provided with a heat- It is preferable that the flow meter 6 is provided to measure the amount of hot water supplied to the hot water tank, the boiler or the tube for floor heating.

The first branch line 111 connecting between the control valve 101 and the first heat exchanger 110 may be provided with a high-temperature high-pressure refrigerant supplied through the first branch line 111 to the first heat exchanger 110, Three sides 111a may be provided so as to guide and supply the refrigerant through the refrigerant line to the four-way switching valve 103 side.

The second heat exchanger (120) is a condensing heat exchanger that is selectively supplied to the second branch line (121) and is discharged in such a manner that the high temperature and high pressure refrigerant is heat-exchanged with the outside air to be cooled.

The second heat exchanger 120 may be provided as a condensing heat exchanger having a plurality of radiating fins on the outer surface of the body through which the second branch line 121, to which high-temperature and high-pressure refrigerant is supplied, as well as the first heat exchanger.

The third heat exchanger (130) includes a first expansion valve (112) for expanding the refrigerant that is heat-exchanged to discharge heat while passing through the first heat exchanger (110), and a second expansion valve To the third branch line 114, each of which has a first counterflow 113 in the middle of its length.

And a second expansion valve (122) for expanding the refrigerant discharged from the second heat exchanger (120) while being heat-exchanged to discharge heat. The second expansion valve (122) is connected to the fourth branch line The second line may be provided in the middle of the length of the branch line 124 to prevent the reverse flow of the refrigerant flowing in one direction.

The third heat exchanger (130) is configured such that the expanded low-temperature and low-pressure refrigerant supplied through the third branch line (114) or the fourth branch line (124) arranged to pass through the inside of the body absorbs heat from the outside air, Type heat exchanger.

The refrigerant evaporated while passing through the third heat exchanger (130) is circulated and supplied to the compressor (102) via the four-way switching valve (103).

The third heat exchanger 130 is an evaporation type heat exchanger having a plurality of heat dissipation fins 135 on the outer surface of the body through which the third and fourth branch lines 114 and 124, And may be equipped with a heat exchanger.

The fourth refrigerant line 154 for connecting the third heat exchanger 130 and the four-way switching valve 103 is provided with a second refrigerant line 154 for preventing reverse flow of the low- It is preferable to provide a three-way valve 115.

The upper part 140 includes a thermal siphon 142 filled with a working fluid in an exhaust pipe 1b through which exhaust gas of a high temperature is discharged from the boiler 1 and the refrigerant evaporated in the third heat exchanger 130 Thereby preventing the implantation of moisture condensation occurring at the time of implantation and delaying the implantation.

The thermal siphon 142 is phase-changed from a liquid state to a gaseous state during heat exchange with a high temperature exhaust gas discharged from the boiler 1 through the exhaust pipe 1b, is evaporated, absorbs exhaust heat and is heated, And a circulation line 141 in which the working fluid is circulated in one direction by transferring heat to the third heat exchanger 130 while being phase-changed from the gas state to the liquid state and being condensed at the time of heat exchange with the third exchanger 130 do.

Here, the thermal siphon 142 may be a hollow cylindrical tube which is disposed on the outer surface of the exhaust pipe 1b for discharging the exhaust gas burned in the boiler, have.

The upper end of the hollow cylindrical tubular body is connected to one end of a circulating line 141 into which the working fluid on the evaporated base is introduced, and the upper end of the hollow cylindrical tubular body is connected to the other end of the circulating line 141 through which the condensed liquid working fluid flows. It is connected to the stage.

That is, one end and the other end of the circulation line 141 are operated in accordance with the phase change due to the evaporation of the working fluid, which is heat-exchanged in a non-contact manner in the exhaust pipe 1b, and the condensation of the working fluid heat-exchanged in the third exchanger 130 And a closed loop circulation pipe connected to the upper and lower ends of the thermal siphon 142 so that one-way circulation of the fluid can be smoothly performed by its own weight, and a certain amount of working fluid is filled in the working fluid.

Accordingly, the working fluid of the thermal siphon 142 evaporated by the exhaust heat of the exhaust gas generated when the boiler is operated is heat-exchanged through the third heat exchanger 130 through the circulation line 141, And is condensed to provide a heat source for the working fluid that is phase-changed through the circulation line 141 to the third heat exchanger 130, which is an evaporative heat exchanger constituting the heat pump. Therefore, And the temperature of the outside air sucked into the evaporating heat exchanger constituting the heat pump is artificially raised so that the defrosting heat exchanger is fundamentally removed without needing an additional defrosting system so that congestion due to moisture condensation occurring on the surface of the evaporating heat exchanger does not occur Or delay.

Meanwhile, the evaporation area where the exhaust heat of the exhaust gas and the working fluid of the thermal siphon are heat-exchanged is circulated through the third heat exchanger 130 and the circulation line 141 so that the one-way circulation of the working fluid through the circulation line 141 can be smoothly performed. It is preferable that the working fluid of the heat exchanger 141 is provided at a relatively lower position than the condensation region where heat exchange is performed.

In this case, the thermal siphon 142 is disposed at a position relatively lower than the installation position of the third heat exchanger 130 constituting the heat pump, so that the thermal siphon 142 is heat-exchanged in the third heat exchanger 130, A series of circulation operations in which the working fluid is recycled to the thermal siphon 142 can be smoothly performed without clogging due to its own weight.

The throttle valve 143 is provided in the middle of the length of the circulation line 141 between the thermal siphon 142 and the third heat exchanger 130 to prevent condensation in the third heat exchanger It is desirable to control the unnecessary circulation of the working fluid in a period other than the winter season for delaying the operation.

The refrigerant supplied to the inside of the third heat exchanger 130 and the refrigerant supplied to the circulation line 141 when the first expansion valve 112 or the second expansion valve 122 is opened are provided at the rear end of the third heat exchanger 130, The auxiliary heat exchanger 140a in the form of a dual pipe heat exchanger is further provided so that the working fluid recirculated to the thermal siphon 142 through the heat exchanger 142 can be heat-exchanged with each other to raise the temperature of the refrigerant.

Although the present invention has been described in detail with reference to the specific embodiments of the invention described above, it is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. It is to be expressly understood, however, that all such equivalents and modifications by such simple design variations or modifications are expressly included within the scope of the present invention.

1: Boiler
2: Hot water tank
101: Control variable
102: compressor
103: Four-way switching valve
110: first heat exchanger
111: First quarter line
114: Third quarter line
120: second heat exchanger
121: Second quarter line
124: Fourth quarter line
130: third heat exchanger
140:
141: circulation line
142: Thermal siphon
143: opening / closing valve

Claims (8)

An apparatus for recovering exhaust heat of an exhaust gas discharged from a boiler,
A control valve for branching the high-temperature and high-pressure refrigerant discharged from the four-way switching valve for switching the traveling direction of the refrigerant discharged from the compressor compressing the refrigerant to the first branch line or the second branch line;
A first heat exchanger to heat and cool the high-temperature and high-pressure refrigerant selectively supplied through the first branch line to heat-exchange with heat supplied from the outside;
A second heat exchanger for heating and discharging the high-temperature high-pressure refrigerant selectively supplied through the second branch line to heat exchange with the outside air;
And a fourth branch line connected to a third branch line having a first expansion valve for expanding the refrigerant discharged from the first heat exchanger and having a second expansion valve for expanding the refrigerant discharged from the second heat exchanger A third heat exchanger for expanding the refrigerant to absorb heat from the outside air to be evaporated, and discharging the evaporated refrigerant to the compressor; And
A thermal siphon which is evaporated during heat exchange with the exhaust gas discharged from the boiler and connected to a circulation line in which a working fluid to be condensed when heat exchange with the third exchanger is circulated in one direction is provided in an exhaust pipe through which the exhaust gas is discharged, An upper portion for providing a heat source for preventing condensation of water generated during evaporation of refrigerant in the third heat exchanger; And an exhaust heat recovering device for recovering exhaust heat of the boiler using the thermal siphon. The method according to claim 1,
Wherein the thermal siphon is made of a hollow cylindrical tube having an inner circumferential surface that is in contact with an outer surface of a discharge pipe for discharging the exhaust gas from the boiler and is filled with a predetermined amount of working fluid. Exhaust heat recovery device. 3. The method of claim 2,
The upper end of the hollow cylindrical tubular body is connected to one end of a circulating line through which the working fluid on the evaporated gas flows. The upper end of the hollow cylindrical tubular body is connected to the other end of the circulating line through which the working fluid in the condensed liquid flows out. Heat recovery device for boiler using thermal siphon. The method according to claim 1,
Wherein the thermal siphon is disposed at a position relatively lower than an installation position of the third heat exchanger so as to smoothly supply circulation of the working fluid that is phase-changed from the third heat exchanger to the liquid phase. Exhaust heat recovery system of boiler. The method according to claim 1,
Wherein the first heat exchanger is connected to one of a boiler, a floor heating tube, and a hot water tank via a hot water line through a water supply line to which water is supplied from the outside, Exhaust heat recovery device. 6. The method of claim 5,
The hot water line may include a first branching hot water line connected to the boiler at one end via three sides so as to selectively supply hot water to the boiler or the bottom tube for heating the floor, And the hot water line is connected to the hot water line. 6. The method of claim 5,
Wherein the hot water line is connected to the hot water tank so as to store hot water through other three sides provided in the middle of the length. The method according to claim 1,
Further comprising an auxiliary heat exchanger disposed at a rear end of the third heat exchanger for exchanging heat between the working fluid recirculated to the thermal siphon and the refrigerant supplied to the interior of the third heat exchanger to increase the temperature of the refrigerant. Exhaust heat recovery system of boiler using.

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