The present invention relates to a heat cycle system including a compressor, an expander, a power generator, first and second heat exchangers, and a composite heat cycle electric power generation system using the heat cycle system. More particularly, the present invention relates to a heat cycle system and a composite heat cycle electric power generation system having such a heat cycle system combined with a Rankine cycle system. In the heat cycle system, working gas compressed in a compressor is chilled and condensed as it passes a heat dissipating side of the first heat exchanger, after driving the first turbine, and is thereafter increased in pressure by a pump to form high-pressure working liquid, which is expanded and evaporated in an expander to form working gas, which is heated (heat crossing) as it passes heat receiving sides of the first and second heat exchangers, and is thereafter introduced to the compressor.
There have heretofore been many inventions of heat cycle systems that are capable of converting heat into work or electric power with a high efficiency, using working liquid. For example, JP-A-54-27640 (Japanese Patent Public Disclosure) discloses an electric power generation system that recovers thermal energy of high-temperature exhaust gas. The electric power generation system has a waste heat boiler installed at the upstream side of high-temperature exhaust gas flow path and a fluid preheater at the downstream side thereof. JP-A-61-229905 or GB 2 174 148 A discloses a process of mechanical power generation using a binary cycle comprising a first cycle using two immiscible fluids and a second cycle using a refrigerant fluid. JP-A-2-40007 discloses a power system wherein a reverse Rankine cycle and a Rankine cycle are combined.
First, the thermal efficiency of the heat cycle system will be described below. Assuming that while a working substance is performing one cycle, i.e. undergoing successive changes and then returning to the previous state, it receives a quantity of heat Qh from a high heat source at a temperature Th and loses a quantity of heat Qb from a low heat source at a temperature Tb to do work L (assumed to be a value expressed in terms of heat quantity) to the outside, the following relationship holds:
Qh=Qb+L (Eq. 1)
In heat engines, the work L is given to the outside. In refrigerators or heat pumps, the work L is given to working fluid from the outside. In the case of heat engines, it is desirable that the quantity of heat Qh received from the high heat source should be minimum, and the work L given to the outside should be maximum. Accordingly, the following equation is referred to as thermal efficiency:
η=L/Qh (Eq. 2)
From the above equation, L may be rewritten as follows:
η=(Qh−Qb)/Qh (Eq. 3)
The thermal efficiency η of a heat engine that performs a reversible Carnot cycle may be expressed by using thermodynamic temperatures Th° K. and Tb° K. as follows:
η=(Th−Tb)/Th=1−(Tb/Th) (Eq. 4)
In general, an apparatus that transfers heat from a low-temperature object to a high-temperature object is called a “refrigerator”. The refrigerator is an apparatus that is generally used for the purpose of cooling objects. Meanwhile, an apparatus that transfers heat from a low-temperature object to a high-temperature object to heat the latter is referred to as a “heat pump”. The name “heat pump” may be regarded as an alias for the refrigerator when the usage is changed. The heat pump is used, for example, for a heating operation of an air conditioner for heating and cooling. The relationship between the quantity of heat Qb absorbed from a low-temperature object, the quantity of heat Qh given to a high-temperature object, and the work L (value expressed in terms of heat quantity) done from the outside to operate the heat pump is expressed as follows:
Qh=Qb+L (Eq. 5)
It can be said that, for the same work done, the larger the quantity of heat Qh given, the higher the cost efficiency of the heat pump. Accordingly, the following equation is referred to as the coefficient of performance of the heat pump:
ε=Qh/L (Eq. 6)
From the above Eq. 5, L is:
L=Qh−Qb (Eq. 7)
Hence, the performance coefficient E is expressed as follows:
ε=Qh/(Qh−Qb) (Eq. 8)
Assuming that the absolute temperature of the low heat source is Tb° K. and the absolute temperature of the high heat source is Th° K., a heat pump that performs a reversible Carnot cycle exhibits the largest coefficient of performance among heat pumps operating between the two heat sources. The performance coefficient E of the heat pump is:
ε=Tb/(Th−Tb) (Eq. 9)
The reversible Carnot cycle consists of two isothermal changes and two adiabatic changes and exhibits the maximum thermal efficiency among all cycles operating between the same high and low heat sources.
In the refrigerator shown in
εh=5.4+1=6.4 (Eq. 11)
W=Q−Q2 (Eq. 12)
The thermal efficiency ηS of the turbine S is:
ηS=(Q−Q2)/Q (Eq. 13)
In Eq. 12 and Eq. 13, Q is the quantity of heat retained by the working fluid at the turbine inlet side, and Q2 is the quantity of heat output from the working fluid at the turbine outlet side, which is equal to the quantity of waste heat discharged from the condenser Y.
The thermal efficiency η0 of the heat cycle system shown in
η0=W/Q (Eq. 14)
If W in Eq. 14 is replaced by W=Q−Q2 of Eq. 12, we have:
η0=(Q−Q2)/Q (Eq. 16)
This is the same as the above-mentioned ηS. Therefore, the following relationship holds:
η0=ηS (Eq. 17)
In the heat cycle system of
0≦Q3≦Q2 (Eq. 18)
and, at the same time, the quantity of heat input to the boiler is reduced by the same amount as the quantity of heat transferred from the condenser Y, then the boiler input heat quantity is Q−Q3. The quantity of heat retained by steam Fg at the inlet of the turbine S is given by:
Boiler input heat quantity (Q−Q3)+(heat quantity Q3 transferred by Y2)=Q (Eq. 19)
The quantity of heat retained by steam Fg at the outlet of the turbine S can be regarded as being Q2. Therefore, power W (value expressed in terms of heat quantity) generated from the turbine S is:
W=Q−Q2 (Eq. 20)
Hence, the thermal efficiency ηS of the turbine S is:
ηS=(Q−Q2)/Q (Eq. 21)
Thus, the thermal efficiency ηS of the turbine S is the same as in the case where the waste heat Q2 from the condenser Y is not utilized.
In the heat cycle system of
η=W/(Q−Q3)=(Q−Q2)/(Q−Q3) (Eq. 23)
In the heat cycle system of
η=(Q−Q2)/Q (Eq. 24)
In the case of 0≦Q3≦Q2 . . . (Eq. 18), we have:
η=(Q−Q2)/(Q−Q3) (Eq. 25)
In the case of Eq. 25, the denominator is smaller than that in Eq. 24 by −Q3, and hence the value of η becomes correspondingly larger than in Eq. 24.
If the whole Q2 of waste heat from the condenser is transferred to the condensate at the upstream or downstream side of the pump P, we have:
Q2=Q3 (Eq. 26)
Hence, the thermal efficiency η of the heat cycle system is:
η=1 (Eq. 27)
In the heat cycle system of
η=(Q−Q2)/(Q−Q3) (Eq. 28)
If the denominator and numerator of Eq. 28 are each divided by Q, we have:
η=[(Q−Q2)/Q]/[(Q−Q3)/Q] (Eq. 29)
Eq. 29 may be modified as follows:
η=[(Q−Q2)/Q]/[1−(Q3/Q)] (Eq. 30)
If ηS=(Q−Q2)/Q . . . (Eq. 21) is inserted into Eq. 30, we have:
η=ηS/(1−Q3/Q) (Eq. 32)
In the present invention, even heat having low utility value, such as waste heat, is taken into the heat cycle system by using a heat pump, and a power output is taken out by a turbine in the heat cycle system. The heat cycle system according to the present invention uses heat crossing to extract power from the turbine at high efficiency. When the whole of waste heat Q2 from the condenser Y is utilized, the thermal efficiency η of the heat cycle system is η=1 according to Eq. 27.
As will be understood from the above Eq. 32, the thermal efficiency η of the heat cycle system is determined by the thermal efficiency ηS of the turbine S and the heat quantity Q3 transferred from the waste heat of the condenser Y to the condensate at the upstream or downstream side of the pump P. As Q3 increases to approach Q, the denominator of Eq. 30, i.e. (1−Q3/Q), decreases. Consequently, η increases. It is difficult to increase the heat crossing ratio Q3/Q in heat cycles other than the refrigerating cycle. The reason for this is that it is impossible to increase the temperature difference between a high heat source and a low heat source for heat transfer (heat crossing). Further, Eq. 27 cannot be realized in heat cycles other than the refrigerating cycle.
An object of the present invention is to provide a high-efficiency heat cycle system including a compressor, an expander, and first and second heat exchangers and a composite heat cycle electric power generation system using the system. Another object of the present invention is to provide a heat cycle system that is capable of using a dissipating side of the second heat exchanger of the heat cycle system as a low-temperature chamber such as a chamber to be air-conditioned, a refrigerator, or an ice-making chamber, or a dissipating portion for waste heat of various types. Another object of the present invention is to provide a high-efficiency heat cycle system adapted to transfer waste heat or heat in nature to working fluid and use the heat. Another object of the present invention is to improve the thermal efficiency of a composite heat cycle system formed by combining a steam turbine and a refrigerator. Another object of the present invention is to improve the thermal efficiency of the heat cycle electric power generation system by transferring (heat crossing) the waste heat of steam turbine outlet steam to working fluid at the steam turbine inlet side. Another object of the present invention is to provide a heat cycle system that is capable of forming a low heat source by combining a heat receiving side (heat absorbing side) of the heat cycle system with a heat dissipating side of a refrigerating machine, the low heat source having such an extremely low temperature as to liquefy a gas such as LNG or LPG.
A further object of the present invention is to convert low-temperature waste heat in a Rankine cycle, into a high-temperature thermal output. A still further object of the present invention is to provide a heat cycle system wherein a refrigeration output of a refrigerator is used as a low heat source of a condenser (cooler) installed at the turbine outlet in a Rankine cycle, and the refrigerator is operated as a heat pump, thereby allowing heat emitted from the condenser to be raised in temperature and supplied as a thermal output to the outside. In the present invention, the heat crossing ratio Q3/Q is increased by using a refrigerating cycle, so that η=1 . . . (Eq. 27) is realized in η=ηS/(1−Q3/Q) . . . (Eq. 32), or η is made as close to 1 as possible. In the present invention, the refrigerating cycle has a turbine installed upstream of a condenser in a refrigerating cycle in which a refrigerant is compressed by a compressor. Other objects of the present invention will be made apparent in the following description of the invention.
A heat cycle system (basic cycle system) according to the present invention includes a compressor, a first turbine, first and second heat exchangers, a first pump, and an expander. Working gas compressed in the compressor (C) drives the first turbine (S). Thereafter, the working gas is cooled by passing through the heat dissipating side (71) of the first heat exchanger (7) and then raised in pressure by the pump (P) to form high-pressure working liquid (Fe). High-pressure working liquid (Fe) is expanded and evaporated in the expander (K, V) to form working gas (Fg). Working gas (Fg) is heated as it passes the heat receiving side (82) of the second heat exchanger and is thereafter introduced into the compressor. The heat dissipating side (81) of the second heat exchanger is comprised of a heat dissipating portion of the refrigerating machine or a waste-heat dissipating portion of a heating machine (30).
The heat cycle system of the present invention can include the following features: (1) the expander is a reaction water turbine (K); and high-pressure working liquid (Fe) drives the reaction water turbine (K) to output work (W2), and is expanded and evaporated to form working gas (Fg); (2) working gas (Fg) is heated as it passes a heat receiving side (72) of the first heat exchanger and a heat receiving side (82) of the second heat changer, and is thereafter introduced to the compressor C; (3) the refrigerating machine is used for an air-conditioner, a refrigerator, or an ice-maker; (4) the expander is an expansion valve (V), and high-pressure working liquid (Fe) is expanded and evaporated through the expansion valve (V) to form working gas (Fg); (5) the waste-heat dissipating portion of the heating machine (30) is a heat dissipating portion for dissipating waste heat from a lubricant cooling system of the compressor, first turbine, first power generator (G), and a compressor drive motor; and (6) the heat cycle system includes an output terminal (11) for supplying electric power to the outside of the first power generator (G) that is driven by the first turbine (S); and a conducting wire (12) for electrically connecting the first power generator (G), the output terminal (11), a motor (M) for driving the compressor, and a motor (M2) for driving the first pump.
The composite heat cycle system of the present invention comprises: a refrigerator (J) including a compressor, first and second heat exchangers, and an expander; and a steam engine (A) including a boiler, a second turbine, a condenser, a third power generator (G3) driven by the second turbine, and a second pump. Working gas compressed in the compressor (C) is chilled as it passes a heat dissipating side (71) of a first heat exchanger (7) to form working liquid (Fe), which is expanded in an expansion valve (V) to form working gas (Fg), which is heated as it passes a heat receiving side (82) of a second heat exchanger, and is thereafter introduced to the compressor. Steam (Eg) generated by a boiler (B) is chilled as it passes a heat dissipating side (81) of a condenser (Y), after driving a second turbine (S2), and is increased in pressure by a second pump (P2) to form high-pressure condensate (Ee), which is heated as it passes a heat receiving side (73) of the first heat exchanger, and is thereafter brought back to the boiler (B). The heat receiving side of the condenser (Y) is comprised of the heat receiving side (82) of the second heat exchanger. The first heat exchanger can comprise a heat receiving portion (74) for feedwater.
The composite heat cycle system of the present invention comprises: a heat cycle system (basic cycle system) including a compressor, a first turbine, a first heat exchanger, a first pump, an expander, and a first power generator (G); and a steam engine including a boiler, a second turbine, a third power generator (G3), a condenser, and a second pump. Working gas compressed in a compressor (C) is chilled as it passes a heat dissipating side (71) of a first heat exchanger (7), after driving a first turbine (S), and is thereafter increased in pressure by a first pump (P) to form high-pressure working liquid (Fe), which is expanded and evaporated in an expander (K, V) to form working gas (Fg), which is introduced to the compressor. Steam (Eg) generated by a boiler (B) is chilled by a condenser (Y), after driving a second turbine (S2), and is increased in pressure by a second pump (P2) to form high-pressure condensate (Ee), which is brought back to the boiler (B). The working gas is heated as it passes a heat receiving side (72) of the first heat exchanger and a heat receiving side (82) of the condenser (Y), and is thereafter is introduced to the compressor C.
The heat cycle system of the present invention can include the following features: (1) high-pressure condensate (Ee) is heated on a second heat receiving side (73) of the first heat exchanger or a heat receiving side (83) of the condenser (Y), before being brought back to the boiler (B); and (2) the heat cycle system further comprises: the first power generator (G); a third power generator (G3) for converting work output from the second turbine (S2) of the steam engine into electric power; an output terminal (11) for supplying electric power to the outside; and a conducting wire for electrically connecting the first power generator, the third power generator, and the output terminal (11). The electric power supply system of the present invention is characterized in that electric power generated by the composite heat cycle electric power generation system can be delivered through power lines to a power consumption area 500 km or more away.
The composite heat cycle system of the present invention comprises a combination of: a first heat cycle system including a compressor, a first turbine, first and second heat exchangers, a first pump, and an expander; and a second heat cycle system including a second compressor, a condenser, a second expander, and an evaporator. In the composite heat cycle system, working gas compressed in a compressor (C) is chilled as it passes a heat dissipating side (71) of a first heat exchanger (7), after driving a first turbine (S), and is thereafter increased in pressure by the first pump (P) to form high-pressure working liquid (Fe), which is expanded and evaporated in an expander (V) to form working gas (Fg), which is heated as it passes a heat absorbing side (82) of a second heat exchanger (8), and is thereafter brought back to the compressor. A refrigerant gas (8g) compressed in a second compressor (C2) is chilled as it passes a condenser (81) to form a refrigerant liquid (8e), which is expanded in a second expander (V2) and evaporated on a heat absorbing side (92) of an evaporator (9), while absorbing heat on a heat dissipating side (91) of the evaporator (9), so as to form a refrigerant gas (8g), which is brought back to the second compressor (C2). The heat dissipating side (81) of the second heat exchanger comprises the condenser.
The composite heat cycle electric power generation system of the present invention comprises: a heat cycle system including a first compressor, a first turbine, a power generator, first and second heat exchangers, a first pump, an expander, and a first power generator; and an open-type gas turbine including a second compressor, a combustor, a second turbine, and a third power generator. In this electric power generation system, working gas (Fg) compressed in a compressor (C) is chilled as it passes a heat dissipating side (71) of a first heat exchanger (7), after driving a first turbine (S), and is thereafter increased in pressure by the first pump (P) to form high-pressure working liquid (Fe), which is expanded and evaporated in an expander (V) to form working gas (Fg), which is heated as it passes a heat receiving side (72) of the first heat exchanger and a heat receiving side (82) of the second heat exchanger, and is thereafter brought back to the compressor (C). Inlet air (34) is compressed in a second compressor (C2) and is supplied to a combustor (35) in which fuel is mixed with compressed air and is ignited for combustion to generate combustion gas. After driving the second turbine (S2), the combustion gas is reduced in temperature as it passes a heat dissipating side (81) of the second heat exchanger and is discharged as an exhaust gas (36) into the atmosphere, such that the first power generator (G) and the third power generator (G3) are driven by the first and second turbines (S) and (S2).
The power generating heat output facility of the present invention comprises: a heat cycle system including a compressor, a first turbine, a power generator driven by the first turbine, first and second heat exchangers, a first pump, and an expander and an electric boiler. In this power generating heat output facility, working gas (Fg) compressed in a compressor (C) is chilled as it passes a heat dissipating side (71) of a first heat exchanger (7), after driving a first turbine (S), and is thereafter increased in pressure by a first pump (P) to form high-pressure working liquid (Fe), which is expanded and evaporated in an expander (V) to form working gas (Fg), which is heated as it passes a heat receiving side (82) of the second heat exchanger, and is brought back to the compressor. Water (U) for heat output is heated on a heat receiving side (73) of the first heat exchanger (7) and is thereafter further heated by the electric boiler (15) to a predetermined temperature, and electric power generated by a power generator (G) driven by the first turbine is supplied to the electric boiler (15). Preferably, working gas is heated as it passes the heat receiving side (72) of the first heat exchanger (7) before passing the heat receiving side (82) of the second heat exchanger, and a heat dissipating side (81) of the second heat exchanger is comprised of a low-temperature chamber or a heat dissipating portion for waste heat.
A: heat engine (Rankine cycle), B: boiler, C: compressor, E: performance coefficient, η: thermal efficiency of heat cycle system, ηS: thermal efficiency of turbine as used singly, Eg: steam, Ee: water (feedwater or condensate), Fg: refrigerant gas, Fe: refrigerant liquid, G, G2, G3: electric generator, J: heat cycle system (refrigerator, heat pump), K: water turbine, L, L2: work (input), N: fuel cell, M, M2: motor, P, P2: pump, Q, Q2, Q3, Q4: heat quantity, S, S2: turbine, U: water, V: expansion valve, W, W2, W3: work (output), Y: condenser, 8: heat exchanger, 9: evaporator, 15: electric boiler, 30: heating machine, 31: heating machine body, 32: open-type gas turbine, 33: flue (processing device), 34: inlet air, 35: combustor, 36: exhaust gas, 41: cooling system, 71, 81, 91: heat dissipating side, 72, 73, 74, 82, 83: heat receiving side (heat absorbing side), 91, 93: shaft, 92: heat absorbing side, 94: connector
In the heat cycle system J of
In the heat cycle system of
(L+Q4) (Eq. 33)
A first generator G to convert W to electric power is electrically connected through a lead 12 to an output terminal 11.
In the heat cycle system of
The heat dissipating side 81 of the heat exchanger 8 in the heat cycle system of
In the composite heat cycle system according to the fourth embodiment of the present invention shown in
In the composite heat cycle system of
η=(400−60)/(400+273.15)≈0.505 (Eq. 45)
On the other hand, when the heat pump J is operated as shown in
η≈0.579 (Eq. 46)
This shows that operating the heat pump in the composite heat cycle system of
0.579−0.505=0.074 (Eq. 47)
Next, let us discuss the heat crossing in the heat cycle system of
In a case where the heat pump is operated to effect heat crossing, the condensate temperature (turbine outlet) is 10° C., and the feedwater temperature at the boiler inlet is 70° C. Therefore, as compared to the boiler inlet feedwater temperature when no heat crossing is effected, i.e. 10° C., it is possible to save a quantity of heat which would otherwise be required to raise the feedwater temperature by 60° C., i.e. 60 units of quantity of heat. This is expressed as follows:
60/779=0.077 (Eq. 48)
Therefore, the reduction in the input heat quantity by heat crossing improves the thermal efficiency of the heat cycle system of
From the above Eq. 32,
η=ηS/(1−Q3/Q) (Eq. 32), i.e.
η/ηS=1/(1−Q3/Q) (Eq. 49)
the thermal efficiency of the heat cycle system is:
1÷(1−0.077)=1.08 (Eq. 50)
Thus, the thermal efficiency improves by approximately 8%.
Next, let us discuss the increase of heat drop due to heat crossing in the heat cycle system of
ηS=(400−10)/(400+273.15)=0.579 (Eq. 51)
Multiplying the thermal efficiency ηS, i.e. 0.579, by the above-described increase rate of the thermal efficiency finds that the thermal efficiency of the heat cycle system is 0.625.
In the composite heat cycle device of
When the input L of the compressor C is thrown into each element of the heat pump J on the right side of
εh=5.4+1=6.4 (Eq. 52)
The output W of the turbine S is given by:
W=εh×ηS=6.4×0.28≈1.7 (Eq. 53)
The heat crossing quantity Q3 at the outlet of the heat exchanger 7 is:
Q3=6.4−1.7=4.7 (Eq. 54)
The heat quantity Q4 absorbed from the outside in the heat exchanger 8 is:
Q4=refrigerator performance coefficient−Q3 (Eq. 54)
Therefore, the heat quantity Q4 is:
Q4=5.4−4.7=0.7 (Eq. 56)
Assuming that the quantity of heat transferred in the condenser Y of the composite heat cycle system of
In the composite heat cycle system of
A refrigerant gas 8g compressed in the second compressor C2 is chilled as it passes the condenser 81, so as to form a refrigerant liquid 8e, which is expanded in the second expander V2 and evaporated on the heat absorbing side 92 of the evaporator 9, while absorbing heat on the heat dissipating side 91 of the evaporator 9, so as to form a refrigerant gas 8g, which is brought back to the second compressor C2. The condenser 81 comprises the heat dissipating side 81 of the second heat exchanger. The composite heat cycle system of
The composite heat cycle electric power generation system of
Unlike a conventional electric power generation system, no heat energy is wasted when electric power is generated by the present invention; therefore, heat output (heated water or steam) can be obtained, without any waste, by an electric heater (electric boiler) using this electric power. The present invention uses heat recovered from waste heat by the heat pump to heat the electric boiler and is therefore capable of providing a useful high-temperature heat output.
Number | Date | Country | Kind |
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2005-343235 | Nov 2005 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2006/320369 | 10/12/2006 | WO | 00 | 5/22/2008 |
Publishing Document | Publishing Date | Country | Kind |
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WO2007/063645 | 6/7/2007 | WO | A |
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