EP1936129B1

EP1936129B1 - Method and apparatus of converting heat to useful energy

Info

Publication number: EP1936129B1
Application number: EP07110803.9A
Authority: EP
Inventors: Alexander I. Kalina; Richard I. Pelletier; Lawrence B. Rhodes
Original assignee: Kct Power Ltd
Current assignee: Kct Power Ltd
Priority date: 1998-02-05
Filing date: 1999-07-23
Publication date: 2019-01-02
Anticipated expiration: 2019-07-23
Also published as: DE69938039D1; EP1936129A3; SI1070830T1; EP1936129A2; PT1070830E; DK1936129T3; ES2301229T3; DE69938039T2

Description

Background of the Invention

The invention relates to implementing a thermodynamic cycle to convert heat to useful form.
Thermal energy can be usefully converted into mechanical and then electrical form. Methods of converting the thermal energy of low temperature heat sources into electric power present an important area of energy generation. There is a need for increasing the efficiency of the conversion of such low temperature heat to electric power.
Thermal energy from a heat source can be transformed into mechanical and then electrical form using a working fluid that is expanded and regenerated in a closed system operating on a thermodynamic cycle. The working fluid can include components of different boiling temperatures, and the composition of the working fluid can be modified at different places within the system to improve the efficiency of operation. Systems that convert low temperature heat into electric power are described in Alexander I. Kalina's U.S. Pat. Nos. 4,346,561 ; 4,489,563 ; 4,982,568 ; and 5,029,444 . In addition, systems with multicomponent working fluids are described in Alexander I. Kalina's U.S. Pat. Nos. 4,548,043 ; 4,586,340 , 4,604,867 ; 4,732,005 ; 4,763,480 , 4,899,545 ; 5,095,708 ; 5,440,882 ; 5,572,871 and 5,649,426 .
US-A-4,573,321 discloses a multi-step process for generating energy from a source heat flow, comprising passing a heated media having a mixture of a low volatility component and a high volatility component into a phase separator. The vaporous working fluid is withdrawn from the phase separator and passed into a work zone, such as a turbine, wherein the fluid is expanded. The expanded vaporous working fluid is withdrawn from the work zone and passed into a direct contact condenser or absorber. The separated weak solution is withdrawn from the phase separator and passed into counter-current heat exchange relationship in an interchanger with a portion of media from the direct contact condenser or absorber. The media from the direct contact condenser or absorber is withdrawn and passed into a fluid pressurizing zone. A portion of the media is then pumped into the interchanger where the media is heated and passed into counter-current heat exchange relationship in a trim heater with a portion of the source heat flow. The remaining portion of the media from the fluid pressurizing zone is pumped into counter-current heat exchange relationship in a regenerator with the remaining portion of the source heat flow. The heated media flows from the trim heater and the regenerator are combined to form the heated media and the cycle repeated.
EP-A-0,649,985 discloses a thermal power generator for generating electric power by utilizing a high heat source and a low heat source, comprising an evaporator, a vapor-liquid separator, and an absorber and a regenerator, to increase thermal efficiency of an evaporator and a condenser, and to reduce cost for building apparatuses
US-A-4,756,162 discloses method for utilising sensible heat energy supplied by a high-temperature heating fluid, employing a multi-component working fluid thermodynamic cycle, wherein a solution rich in a lower boiling component is heated in a vapor generator in counter-current heat exchange with the heating fluid to produce a vapor-fluid mixture which is separated in a rectifier into a lean solution and a vapor mixture. The enthalpy of the vapor mixture is optionally increased in a superheater by counter-current heat exchange with said heating fluid at its highest temperature; the vapor mixture is then expanded thereby to perform the function of the cycle; and the spent vapor mixture is dissolved in said lean solution in an absorber so as to regenerate the rich solution. The rich solution leaving the absorber is compressed and divided into a first and second parts. The first part is heated by counter-current heat exchange with said lean solution drawn from the rectifier, whereafter said first part of the rich solution is recycled to the vapor generator, whereas the second part of the rich solution extracts additional heat from the heating fluid leaving the vapor generator, by counter-current heat exchange, and is then fed into the rectifier for counter-current mass and heat exchange with the vapor-liquid mixture formed in the vapor generator.

Summary of the Invention

In accordance with a first aspect of the invention, there is provided a method for implementing a thermodynamic cycle, having the features of claim 1.
In accordance with a second aspect of the invention, there is provided an apparatus for implementing a thermodynamic cycle, having the features of claim 9.
Embodiments of the invention may include one or more of the following advantages. Embodiments of the invention can achieve efficiency of conversion of low temperature heat to electric power that exceeds the efficiency of standard Rankine cycles.
Other advantages and features of the invention will be apparent from the following detailed description of particular embodiments and from the claims.

Brief description of the drawings

The accompanying Figures 1 and 2 and the description thereof, illustrate the invention by way of example. In the drawings:-

Fig. 1 is a diagram of a thermodynamic system for converting heat from a low temperature source to useful form.
Fig. 2 is a diagram of another embodiment of the Fig. 1 system which permits an extracted stream and a completely spent stream to have compositions which are different from the high pressure charged stream.
Fig. 3 is a diagram of a simplified embodiment that does not form part of the invention in which there is no extracted stream.
Fig. 4 is a diagram of a further simplified embodiment that does not form part of the invention.

Detailed Description of the Invention

Referring to Fig. 1, a system for implementing a thermodynamic cycle to obtain useful energy (e.g., mechanical and then electrical energy) from an external heat source is shown. In the described example, the external heat source is a stream of low temperature waste-heat water that flows in the path represented by points 25-26 through heat exchanger HE-5 and heats working stream 117-17 of the closed thermodynamic cycle. Table 1 presents the conditions at the numbered points indicated on Fig. 1. A typical output from the system is presented in Table 5.
The working stream of the Fig. 1 system is a multicomponent working stream that includes a low boiling component and a high boiling component. Such a preferred working stream may be an ammonia-water mixture, two or more hydrocarbons, two or more freons, mixtures of hydrocarbons and freons, or the like. In general, the working stream may be mixtures of any number of compounds with favorable thermodynamic characteristics and solubility. In a particularly preferred embodiment, a mixture of water and ammonia is used. In the system shown in Fig. 1, the working stream has the same composition from point 13 to point 19.
Beginning the discussion of the Fig. 1 system at the exit of turbine T, the stream at point 34 is referred to as the expanded, spent rich stream. This stream is considered "rich" in lower boiling point component. It is at a low pressure and will be mixed with a leaner, absorbing stream having parameters as at point 12 to produce the working stream of intermediate composition having parameters as at point 13. The stream at point 12 is considered "lean" in lower boiling point component.
At any given temperature, the working stream (of intermediate composition) at point 13 can be condensed at a lower pressure than the richer stream at point 34. This permits more power to be extracted from the turbine T, and increases the efficiency of the process.
The working stream at point 13 is partially condensed. This stream enters heat exchanger HE-2, where it is cooled and exits the heat exchanger HE-2 having parameters as at point 29. It is still partially, not completely, condensed. The stream now enters heat exchanger HE-1 where it is cooled by stream 23-24 of cooling water, and is thereby completely condensed, obtaining parameters as at point 14. The working stream having parameters as at point 14 is then pumped to a higher pressure obtaining parameters as at point 21. The working stream at point 21 then enters heat exchanger HE-2 where it is recuperatively heated by the working stream at points 13-29 (see above) to a point having parameters as at point 15. The working stream having parameters as at point 15 enters heat exchanger HE-3 where it is heated and obtains parameters as at point 16. In a typical design, point 16 may be precisely at the boiling point but it need not be. The working stream at point 16 is split into two substreams; first working substream 117 and second working substream 118. The first working substream having parameters as at point 117 is sent into heat exchanger HE-5, leaving with parameters as at point 17. It is heated by the external heat source, stream 25-26. The other substream, second working substream 118, enters heat exchanger HE-4 in which it is heated recuperatively, obtaining parameters as at point 18. The two working substreams, 17 and 18, which have exited heat exchangers HE-4 and HE-5, are combined to form a heated, gaseous working stream having parameters as at point 19. This stream is in a state of partial, or possibly complete, vaporization. In the preferred embodiment, point 19 is only partially vaporized. The working stream at point 19 has the same intermediate composition which was produced at point 13, completely condensed at point 14, pumped to a high pressure at point 21, and preheated to point 15 and to point 16. It enters the separator S. There, it is separated into a rich saturated vapor, termed the "heated gaseous rich stream" and having parameters as at point 30, and a lean saturated liquid, termed the "lean stream" and having parameters as at point 7. The lean stream (saturated liquid) at point 7 enters heat exchanger HE-4 where it is cooled while heating working stream 118-18 (see above) . The lean stream at point 9 exits heat exchanger HE-4 having parameters as at point 8. It is throttled to a suitably chosen pressure, obtaining parameters as at point 9.
Returning now to point 30, the heated gaseous rich stream (saturated vapor) exits separator S. This stream enters turbine T where it is expanded to lower pressures, providing useful mechanical energy to turbine T used to generate electricity. A partially expanded stream having parameters as at point 32 is extracted from the turbine T at an intermediate pressure (approximately the pressure as at point 9) and this extracted stream 32 (also referred to as a "second portion" of a partially expanded rich stream, the "first portion" being expanded further) is mixed with the lean stream at point 9 to produce a combined stream having parameters as at point 10. The lean stream having parameters as at point 9 serves as an absorbing stream for the extracted stream 32. The resulting stream (lean stream and second portion) having parameters as at point 10 enters heat exchanger HE-3 where it is cooled, while heating working stream 15-16, to a point having parameters as at point 11. The stream having parameters as at point 11 is then throttled to the pressure of point 34, obtaining parameters as at point 12.
Returning to turbine T, not all of the turbine inflow was extracted at point 32 in a partially expanded state. The remainder, referred to as the first portion, is expanded to a suitably chosen low pressure and exits the turbine T at point 34. The cycle is closed.
In the embodiment shown in Fig. 1, the extraction at point 32 has the same composition as the streams at points 30 and 34. In the embodiment shown in Fig. 2, the turbine is shown as first turbine stage T-1 and second turbine stage T-2, with the partially expanded rich stream leaving the higher pressure stage T-1 of the turbine at point 31. Conditions at the numbered points shown on Fig. 2 are presented in Table 2. A typical output from the Fig. 2 system is presented in Table 6.
Referring to Fig. 2, the partially expanded rich stream from first turbine stage T-1 is divided into a first portion at 33 that is expanded further at lower pressure turbine stage T-2, and a second portion at 32 that is combined with the lean stream at 9. The partially expanded rich stream enters separator S-2, where it is separated into a vapor portion and a liquid portion. The composition of the second portion at 32 may be chosen in order to optimize its effectiveness when it is mixed with the stream at point 9. Separator S-2 permits stream 32 to be as lean as the saturated liquid at the pressure and temperature obtained in the separator S-2; in that case, stream 33 would be a saturated vapor at the conditions obtained in the separator S-2. By choice of the amount of mixing at stream 133, the amount of saturated liquid and the saturated vapor in stream 32 can be varied.
Referring to Fig. 3, this embodiment does not form part of the invention and differs from the embodiment of Fig. 1, in that the heat exchanger HE-4 has been omitted, and there is no extraction of a partially expanded stream from the turbine stage. In the Fig. 3 embodiment, the hot stream exiting the separator S is admitted directly into heat exchanger HE-3. Conditions at the numbered points shown on Fig. 3 are presented in Table 3. A typical output from the system is presented in Table 7.
Referring to Fig. 4, this embodiment does not form part of the invention and differs from the Fig. 3 embodiment in omitting heat exchanger HE-2.
Conditions at the numbered points shown on Fig. 4 are presented in Table 4. A typical output from the system is presented in Table 8. While omitting heat exchanger HE-2 reduces the efficiency of the process, it may be economically advisable in circumstances where the increased power given up will not pay for the cost of the heat exchanger.
In general, standard equipment may be utilized in carrying out the method of this invention. Thus, equipment such as heat exchangers, tanks, pumps, turbines, valves and fittings of the type used in a typical Rankine cycles, may be employed in carrying out the method of this invention.
In the described embodiments of the invention, the working fluid is expanded to drive a turbine of conventional type. However, the expansion of the working fluid from a charged high pressure level to a spent low pressure level to release energy may be effected by any suitable conventional means known to those skilled in the art. The energy so released may be stored or utilized in accordance with any of a number of conventional methods known to those skilled in the art.
The separators of the described embodiments can be conventionally used gravity separators, such as conventional flash tanks. Any conventional apparatus used to form two or more streams having different compositions from a single stream may be used to form the lean stream and the enriched stream from the fluid working stream.
The condenser may be any type of known heat rejection device. For example, the condenser may take the form of a heat exchanger, such as a water cooled system, or another type of condensing device.

Various types of heat sources may be used to drive the cycle of this invention.

Table 1

#	P Mpa (psiA)	X	T°C (°F)	H KJ/kg (BTU/lb)	G/G30	Flow kg/hr (lb/hr)	Phase
7	2.24 (325.22)	.5156	94.9 (202.81)	191.4 (82.29)	.5978	125,544 (276,778)	SatLiquid
8	2.10 (305.22)	.5156	76.4 (169.52)	103.6 (44.55)	.5978	125,544 (276,778)	Liq 28°
9	1.48 (214.26)	.5156	76.4 (169.50)	103.6 (44.55)	.5978	125,544 (276,778)	Wet .9997
10	1.48 (214.26)	.5533	76.4 (169.52)	210.0 (90.30)	.6513	136,780 (301,549)	Wet .9191
11	1.34 (194.26)	.5533	37.7 (99.83)	-69.3 (-29.79)	.6513	136,780 (301,549)	Liq 53°
12	0.59 (85.43)	.5533	37.5 (99.36)	-69.3 (-29.79)	.6513	136,780 (301,549)	Wet .9987
13	0.59 (85.43)	.7000	37.6 (99.83)	405.7 (174.41)	1	210,021 (463,016)	Wet.6651
14	0.58 (84.43)	.7000	22.4 (72.40)	-88.7 (-38.12)	1	210,021 (463,016)	SatLiquid
15	2.41 (350.22)	.7000	34.9 (94.83)	-30.4 (-13.08)	1	210,021 (463,016)	Liq 73°
16	2.31 (335.22)	.7000	73.6 (164.52)	151.5 (65.13)	1	210,021 (463,016)	SatLiquid
117	2.31 (335.22)	.7000	73.6 (164.52)	151.5 (65.13)	.8955	210,021 (463,016)	SatLiquid
17	2.24 (325.22)	.7000	95.2 (203.40)	704.6 (302.92)	.8955	188,068 (414,621)	Wet .5946
118	2.31 (335.22)	.7000	73.6 (164.52)	151.5 (65.13)	.1045	210,021 (463,016)	SatLiquid
18	2.24 (325.22)	.7000	92.1 (197.81)	653.6 (281.00)	.1045	21,952 (48,395)	Wet .6254
19	2.24 (325.22)	.7000	94.9 (202.81)	699.2 (300.63)	1	210,021 (463,016)	Wet .5978
21	2.45 (355.22)	.7000	22.9 (73.16)	-85.5 (-36.76)	1	210,021 (463,016)	Liq 96°
29	0.59 (84.93)	.7000	35.0 (95.02)	350.6 (150.73)	1	210,021 (463,016)	Wet .6984
30	2.24 (325.22)	.9740	94.9 (202.81)	1454.0 (625.10)	.4022	84,476 (186,238)	SatVapor
32	1.48 (214.69)	.9740	76.8 (170.19)	1399.2 (601.53)	.0535	11,236 (24,771)	Wet .0194
34	0.59 (85.43)	.9740	40.3 (104.60)	1292.7 (555.75)	.3487	73,240 (161,467)	Wet .0467
23	•	Water	18.0 (64.40)	75.4 (32.40)	9.8669	2,072,245 (4,568,519)
24	•	Water	28.6 (83.54)	119.9 (51.54)	9.8669	2,072,245 (4,568,519)
25	•	Water	98.0 (208.40)	410.3 (176,40)	5.4766	1,150,196 (2,535,750)
26	•	Water	76.4 (169.52)	319.9 (137.52)	5.4766	1,150,196 (2,535,750)

Table 2

#	P Mpa (psiA)	X	T°C (°F)	H KJ/kg (BTU/lb)	G/G30	Flow kg/hr (lb/hr)	Phase
7	2.24 (325.22)	.5156	94.9 (202.81)	191.4 (82.29)	.5978	125,544 (276,778)	SatLiquid
8	2.10 (305.22)	.5156	76.4 (169.52)	103.6 (44.55)	.5978	125,544 (276,778)	Liq 28°
9	1.48 (214.19)	.5156	76.4 (169.48)	103.6 (44.55)	.5978	125,544 (276,778)	Wet.997
10	1.48 (214.19)	.5523	76.4 (169.52)	207.5 (89.23)	.6570	137,990 (304,216)	Wet .921
11	1.34 (194.19)	.5523	37.6 (99.74)	-69.3 (-29.96)	.6570	137,990 (304,216)	Liq 53°
12	0.59 (85.43)	.5523	37.5 (99.53)	-69.3 (-29.96)	.6570	137,990 (304,216)	Wet .9992
13	0.59 (85.43)	.7000	37.6 (99.74)	404.6 (173.96)	1	210,021 (463,016)	Wet.6658
14	0.58 (84.43)	.7000	22.4 (72.40)	-88.7 (-38.12)	1	210,021 (463,016)	SatLiquid
15	2.41 (350.22)	.7000	34.9 (94.74)	-30.7 (-13.18)	1	210,021 (463,016)	Liq 73°
16	2.31 (335.22)	.7000	73.6 (164.52)	15.15 (65.13)	1	210,021 (463,016)	SatLiquid
117	2.31 (335.22)	.7000	73.6 (164.52)	151.5 (65.13)	.8955	210,021 (463,016)	SatLiquid
17	2.24 (325.22)	.7000	95.2 (203.40)	704.6 (302.92)	.8955	188,068 (414,621)	Wel.5946
118	2.31 (335.22)	.7000	73.6 (164.52)	151.5 (65.13)	.1045	210,021 (463,016)	SatLiquid
18	2.24 (325.22)	.7000	92.1 (197.81)	653.6 (281.00)	.1045	21,952 (48,395)	Wet.6254
19	2.24 (325.22)	.7000	94.9 (202.81)	699.2 (300.63)	1	210,021 (463,016)	Wet .5978
21	2.31 (355.22)	.7000	22.9 (73.16)	-85.5 (-36.76)	1	210,021 (463,016)	Liq 96°
29	0.59 (84.93)	.7000	35.0 (94.96)	349.8 (150.38)	1	210,021 (463,016)	Wet.6989
30	2.24 (325.22)	.9740	94.9 (202.81)	1454.0 (625.10)	.4022	84,476 (186,238)	SatVapor
31	1.48 (214.69)	.9740	77.0 (170.63)	1400.5 (602.12)	.4022	84,476 (186,238)	Wet .0189
32	1.48 (214.69)	.9224	77.0 (170.63)	1255.9 (539.93)	.0593	11,236 (27,437)	Wel.1285
33	1.48 (214.69)	.9829	77.0 (170.63)	1425.5 (612.87)	.3430	72,030 (158,800)	SatVapor
34	0.59 (85.43)	.9829	39.0 (102.18)	1313.3 (564.60)	.3430	72,030 (158,800)	Wet.0294
35	1.48 (214.69)	.5119	77.0 (170.63)	105.7 (45.44)	.0076	1,600 (3,527)	SatLiquid
23	•	Water	18.0 (64.40)	75.4 (32.40)	9.8666	2,072,245 (4,568,371)
24	•	Water	28.6 (83.50)	119.8 (51.50)	9.8666	2,072,245 (4,568,371)
25	•	Water	98.0 (208.40)	410.3 (176.40)	5.4766	1,150,196 (2,535,750)
26	•	Water	76.4 (169.52)	319.9 (137,52)	5.4766	1,150,196 (2,535,750)

Table 3

#	P Mpa (psiA)	X	T°C (°F)	H KJ/kg (BTU/1b)	G/G30	Flow kg/hr (lb/hr)	Phase
10	2.01 (291.89)	.4826	95.2 (203.40)	187.8 (80.72)	.6506	133,576 (294,484)	SatLiquid
11	1.87 (271.89)	.4826	42.8 (109.02)	-54.8 (-23.56)	.6506	133,576 (294,484)	Liq 89°
12	0.52 (75.35)	.4826	42.8 (109.07)	-54.8 (-23.56)	.6506	133,576 (294,484)	Wet .9994
13	0.52 (75.35)	.6527	42.8 (109.02)	418.7 (180.50)	1	205,317 (452,648)	Wet .6669
14	0.51 (74.35)	.6527	22.4 (72.40)	-110.3 (-47.40)	1	205,317 (452,648)	SatLiquid
15	2.18 (316.89)	.6527	40.0 (103.99)	-28.9 (-12.43)	1	205,317 (452,648)	Liq 64°
16	2.08 (301.89)	.6527	73.6 (164.52)	128.9 (55.41)	1	205,317 (452,648)	SatLiquid
17	2.01 (291.89)	.6527	95.2 (203.40)	635.5 (273.22)	1	205,317 (452,648)	Wet .6506
21	2.22 (321.89)	.6527	22.8 (73.04)	-107.4 (-46.18)	1	205,317 (452,648)	Liq 97°
29	0.51 (74.85)	.6527	38.2 (100.84)	341.4 (146.74)	1	205,317 (452,648)	Wet.7104
30	2.01 (291.89)	.9693	95.2 (203.40)	1469.2 (631.64)	.3494	71,741 (158,164)	SatVapor
34	0.52 (75.35)	.9693	42.55 (108.59)	1303.6 (560.44)	.3494	71,741 (158,164)	Wet .0474
23	•	Water	18.0 (64.40)	75.4 (32.40)	8.1318	1,669,606 (3,680,852)
24	•	Water	31.2 (88.27)	130.9 (56.27)	8.1318	1,669,606 (3,680,852)
25	•	Water	98 (208.40)	410.3 (176.40)	5.6020	1,150,196 (2,535,750)
26	•	Water	76.4 (169.52)	319.9 (137.52)	5.6020	1,150,196 (2,535,750)

Table 4

#	P Mpa (psiA)	X	T°C (°F)	H KJ/kg (BTU/lb)	G/G30	Flow kg/hr (lb/hr)	Phase
10	1.48 (214.30)	.4059	95.2 (203.40)	186.5 (80.05)	.7420	179,411 (395,533)	SatLiquid
11	1.34 (194.30)	.4059	25.4 (77.86)	-128.6 (-55.30)	.7420	179,411 (395,533)	Liq 118°
12	0.36 (52.48)	.4059	25.7(78.17)	-128.6 (-55.30)	.7420	179,411 (395,533)	Liq 32°
29	0.36 (52.48)	.5480	40.3 (104.46)	247.6 (106.44)	1	241,801 (533.080)	Wet .7825
14	0.36 (51.98)	.5480	22.4 (72.40)	-139.7 (-60.06)	1	241,801 (533.080)	SatLiquid
21	1.68 (244.30)	.5480	22.7 (72.83)	-137.6 (-59.16)	1	241,801 (533.080)	Liq 98°
16	1.55 (224.30)	.5480	73.6 (164.52)	96.0 (41.26)	1	241,801 (533.080)	SatLiquid
17	1.48 (214.30)	.5480	95.2 (203.40)	526.1 (226.20)	1	241,801 (533.080)	Wet .742
30	1.48 (214.30)	.9567	95.2 (203.40)	1503.7 (646.49)	.2580	62,389 (137,546)	SatVapor
34	0.36 (52.48)	.9567	45.7 (114.19)	1329.4 (571.55)	.2580	62,389 (137,546)	Wet.0473
23	•	Water	18 (64.40)	75.4 (32.40)	5.7346	1,386,640 (3,057,018)
24	•	Water	34.2 (93.43)	142.9 (61.43)	5.7346	1,386,640 (3,057,018)
25	•	Water	98 (208.40)	410.3 (176.40)	4.7568	1,150,197 (2,535,750)
26	•	Water	76.4 (169.52)	319.9 (137.52)	4.7568	1,150,197 (2,535,750)

Table 5

Performance Summary KCS34 Case 1
Heat in	28893.87 kW	553.08 KJ/kg (237.78 BTU/lb)
Heat rejected	25638.63 kW	490.76 KJ/kg (210.99 BTU/lb)
∑ Turbine enthalpy drops	3420.86 kW	65.48 KJ/kg (28.15 BTU/lb)
Turbine Work	3184.82 kW	60.96 KJ/kg (26.21 BTU/lb)
Feed pump ΔH 1.36, power	175.97 kW	3.37 KJ/kg (1.45 BTU/lb)
Feed + Coolant pump power	364.36 kW	6.978 KJ/kg (3.00 BTU/lb)
Net Work	2820.46 kW	53.99 KJ/kg (23.21 BTU/lb)

Gross Output	3184.82 kWe
Cycle Output	3008.85 kWe
Net Output	2820.46 kWe

Net thermal efficiency	9.76%
Second law limit	17.56%
Second law efficiency	55.58%
Specific Brine Consumption	407.73 kg/kW hr (899.05 1b/kW hr)
Specific Power Output	2.45 Watt hr/kg (1.11 Watt hr/lb)

Table 6

Performance Summary KCS34 Case 2
Turbine mass flow	58.34 kg/s 463016 lb/hr
Pt 30 Volume flow	4044.45 l/s 514182 ft^3/hr
Heat in	28893.87 kW	212.93 BTU/lb
Heat rejected	25578.48 kW	188.50 BTU/lb
∑ Turbine enthalpy drops	3500.33 kW	25.80 BTU/lb
Turbine Work	3258.81 kW	24.02 BTU/lb
Feed pump ΔH 1.36, power	196.51 kW	1.45 BTU/lb
Feed + Coolant pump power	408.52 kW	3.01 BTU/lb
Net Work	2850.29 kW	21.00 BTU/lb
Gross Output	3258.81 kWe
Cycle Output	3062.30 kWe
Net Output	2850.29 kWe
Net thermal efficiency	9.86 %
Second law limit	17.74 %
Second law efficiency	55.60 %
Specific Brine Consumption	889.65 lb/kW hr
Specific Power Output	1.12 Watt hr/lb

Table 7

Performance Summary KCS34 Case 3
Turbine mass flow	57.03 kg/s 452648 lb/hr
Pt 30 Volume flow	4474.71 l/s 568882 ft^3/hr
Heat in	28893.87 kW	217.81 BTU/lb
Heat rejected	25754.18 kW	194.14 BTU/lb
∑ Turbine enthalpy drops	3300.55 kW	24.88 BTU/lb
Turbine Work	3072.82 kW	23.16 BTU/lb
Feed pump ΔH 1.21, power	170.92 kW	1.29 BTU/lb
Feed + Coolant pump power	341.75 kW	2.58 BTU/lb
Net Work	2731.07 kW	20.59 BTU/lb
Gross Output	3072.82 kWe
Cycle Output	2901.89 kWe
Net Output	2731.07 kWe
Net thermal efficiency	9.45 %
Second law limit	17.39 %
Second law efficiency	54.34 %
Specific Brine Consumption	928.48 lb/kW hr
Specific Power Output	1.08 Watt hr/lb
Heat to Steam Boiler	15851.00 kW	577.22 BTU/lb
Heat Rejected	10736.96 kW	390.99 BTU/lb

Table 8

Performance Summary KCS34 Case 4
Turbine mass flow	67.17 kg/s 533080 lb/hr
Pt 30 Volume flow	7407.64 l/s 941754 ft^3/hr
Heat in	28893.87 kW	184.94 BTU/lb
Heat rejected	26012.25 kW	166.50 BTU/lb
∑ Turbine enthalpy drops	3020.89 kW	19.34 BTU/lb
Turbine Work	2812.45 kW	18.00 BTU/lb
Feed pump ΔH .89, power	147.99 kW	0.95 BTU/lb
Feed + Coolant pump power	289.86 kW	1.86 BTU/lb
Net Work	2522.59 kW	16.15 BTU/lb
Gross Output	2812.45 kWe
Cycle Output	2664.46 kWe
Net Output	2522.59 kWe
Net thermal efficiency	8.73 %
Second law limit	17.02 %
Second law efficiency	51.29 %
Specific Brine Consumption	1005.22 lb/kW hr
Specific Power Output	0.99 Watt hr/lb

Claims

A method for implementing a thermodynamic cycle comprising:
separating a heated gaseous working stream at a first separator(S)including a low boiling point component and a higher boiling point component to provide a heated gaseous rich stream having relatively more of said low boiling point component and a lean stream having relatively less of said low boiling point component,

expanding said heated gaseous rich stream to transform the energy of the stream into useable form and to provide an expanded, spent rich stream (34),

combining said lean stream and said expanded, spent rich stream (34)to provide said working stream,

wherein, after said combining and before said separating, said working stream is condensed by transferring heat to a low temperature source at a first heat exchanger (HE-1), and said working stream is thereafter pumped to a higher pressure,

splitting said working stream into a first working substream (117) and a second working substream (118), and heating said first working substream (117) with an external source of heat (HE-5) to provide a heated first working substream (17),

characterised in that the method comprises heating the second working substream (118) with heat from said lean stream thereby producing a heated second working substream (18) having a first set of thermodynamic characteristics, and

combining said heated first working substream (17) with said heated second working substream (18) having the first set of thermodynamic characteristics to form the heated gaseous working stream.
A method as claimed in claim 1, further comprising transferring, at a second heat exchanger (HE-2), heat from said working stream, prior to said working stream being condensed, to said working stream after said working stream has been pumped to said higher pressure and prior to said heating with said external source of heat.
A method as claimed in claim 2, further comprising transferring, at a third heat exchanger (HE-3), heat from said lean stream to said working stream after said working stream has received heat at said second heat exchanger (HE-2) and prior to said splitting.
A method as claimed in any one of the preceding claims, wherein said expanding takes place in a first expansion step and a second expansion step,
said heated gaseous rich stream being partially expanded to provide a partially expanded rich stream in said first expansion step,
further comprising dividing said partially expanded rich stream into a first portion and a second portion (34),
wherein said first portion (33)is expanded to provide said expanded, spent rich stream in said second expansion step, and
further comprising combining said second portion (34) with said lean stream before said combining of said lean stream and said expanded, spent rich stream.
A method as claimed in claim 4, wherein said dividing includes separating said partially expanded rich stream into a vapor portion and a liquid portion, said first portion (33) including at least some of said vapor portion, and said second portion (34) including said liquid portion.
A method as claimed in claim 4, further comprising combining some of said vapor portion with said liquid portion to provide said second portion (34).
A method as claimed claim 6, further comprising transferring, at a heat exchanger (HE-3), heat from said lean stream and said second portion (34) to said working stream before said working stream has been split into the first working substream (117) and the second working substream (118).
A method as claim in any of the preceding claims, further comprising extracting a partially expanded stream from a turbine (T) and mixing said partially expanded stream with said lean stream to produce a mixed lean stream.
Apparatus for implementing a thermodynamic cycle comprising:
a separator(S) to divide a heated gaseous working stream including a low boiling point component and a higher boiling point component, to provide a heated gaseous rich stream having relatively more of said low boiling point component and a lean stream having relatively less of said low boiling point component,

an expander that is connected to receive at least a portion of said heated gaseous working stream and transform the energy of the stream into useable form and to output an expanded stream,

a mixer that combines said expanded rich stream and said lean stream (12)

a first heat exchanger (HE-1) and a pump that are connected between said expander and said separator(S), said first heat exchanger (HE-1) condensing said expanded stream by transferring heat to a low temperature source, and said pump thereafter pumping said expanded stream to a higher pressure to form the working stream,

a stream splitter (16) connected to split said working stream, after said pumping into a first working substream (117) and a second working substream (118), a heat exchanger to heat the first working substream with an external source of heat (HE-5),

a heat exchanger (HE-4) to heat the second working substream with the lean stream from the separator(s),

a second mixer that combines the first heated working substream with the second working substream, and

a second heat exchanger (HE-2) connected to transfer heat from said working stream (13), prior to said working stream being fully condensed , to said working stream (21) after said working stream has been pumped to said higher pressure at said pump and prior to said working stream being split at said stream splitter,

characterised in that the heated second working substream has a first set of thermodynamic characteristics, and that the combined heated first working substream and heated second working substream having the first set of thermodynamic characteristics form the gaseous working stream.
An apparatus as claimed in claim 9 , further comprising a third heat exchanger (HE-3) connected to transfer heat from said lean stream to said working stream after said working stream has received heat at said second heat exchanger (HE-2) and prior to said working stream being split at said stream splitter.
The apparatus as claimed in claim 9, wherein said expander includes a first expansion stage and a second expansion stage,
said first expansion stage being connected to receive said heated gaseous rich stream and to output a partially expanded rich stream,
further comprising a second separator (S-2) that is connected to receive said partially expanded rich stream and divide it into a first portion (33) and a second portion (32),
wherein said second stage is connected to receive said first portion and expands said first portion to provide said expanded, spent rich stream (34), and
further comprising a third stream mixer that is connected to combine said second portion (32) with said lean stream before said lean stream is combined with said expanded, spent rich stream at said first stream mixer.
An apparatus as claimed in claim 11, wherein said second separator (S-2) is connected to receive said partially expanded rich stream and to separate it into a vapor portion and a liquid portion, said first portion (33) including at least some of said vapor portion, and said second portion (32) including said liquid portion.
An apparatus as claimed in claim 11, wherein said second separator (S-2) includes a fourth stream mixer connected to combine some of said vapor portion from said second separator (S-2) with said liquid portion from said second separator (S-2) to provide said second portion (32).
An apparatus as claimed in claim 11, further comprising a heat exchanger (HE-3) connected to transfer heat from said lean stream and said second portion (32) to said working stream prior to said working stream being split at said stream splitter.