Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
2000-03-27
2001-05-22
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S657000, C060S671000
Reexamination Certificate
active
06233938
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to thermodynamic cycles, and more particularly to a working fluid for use in a Rankine cycle. The Rankine cycle is the standard thermodynamic cycle in general use for electric power generation. The essential elements of a Rankine cycle system are: 1) a boiler to change liquid to vapor at high pressure; 2) a turbine to expand the vapor to derive mechanical energy; 3) a condenser to change low pressure exhaust vapor from the turbine to low pressure liquid; and 4) a pump to move condensate liquid back to the boiler at high pressure.
Water (steam) is the standard Rankine cycle working fluid. Water has many practical advantages. It is abundantly available, it is non-toxic, and generally non-corrosive. However, the thermodynamic properties of water are not the most ideal. A working fluid with more suitable thermodynamic properties, to increase the efficiency of a Rankine cycle, is desired and is an object of this invention.
Various other working fluids have been tried, but water remains the standard.
Prior art that I know of is as follows:
U.S. Pat. No. 4,896,509 to Tamura et al discloses a vapor cycle working fluid of 1,2-dichloro-1,1,2-trifluorethane.
U.S. Pat. No. 4,876,855 discloses vapor cycle working fluids including heptane, perfluorohexane, 1—1 dimethyl cyclohexane, and undecane.
U.S. Pat. No. 4,557,851 to Enjo et al discloses a vapor cycle working fluid of mixtures of trichlorofluoromethane and one of the group: difluoroethane, isobutane, and octafluorocyclobutane.
U.S. Pat. No. 4,530,773 to Enjo et al discloses a vapor cycle working fluid of a mixture of dichlorotetrafluoroethane and difluoroethane.
U.S. Pat. No. 4,465,610 to Enjo et al discloses vapor cycle working fluids of mixtures of pentafluoropropanol and water.
U.S. Pat. No. 4,224,795 discloses a vapor cycle working fluid of monochlorotetrafluoroethane.
U.S. Pat. No. 4,008,573 to Petrillo discloses a vapor cycle working fluid of trifluoroethanol.
U.S. Pat. No. 3,802,185 to Tulloch discloses a vapor cycle working fluid of 1,2,4-trichlorobenzene.
U.S. Pat. No. 3,753,345 discloses a vapor cycle working fluid of a mixture of hexafluorobenzene an perfluorotoluene.
U.S. Pat. No. 3,702,534 to Bechtold discloses a vapor cycle working fluid of perhalogenated benzenes of the formula C
6
Br
x
Cl
y
F
z
.
The following prior art is filed herewith, and is incorporated by reference in this specification as background material:
1. Steam Bottoming Cycles for Combined Plants (April 1978) by R. W. Foster-Pegg
2. Powerplant Technology by M. M El-Wakil pages 30-35; 342-345; 348-350
3. A Theoretical Comparison Of The Rankine And Kalina Cycles (November 1985) by El-Sayed and Tribus.
4. Waste Heat Boiler Deskbook by V. Ganapathy pages 205-213
5. Thermal Decomposition Studies On Methylene Chloride From 450 to 850° F., a report on research commissioned by me, together with a letter of transmittal thereof from Kellogg Brown & Root to me (Dec. 22, 1998). this report relates to thermophysical properties of methylene chloride.
SUMMARY OF THE INVENTION
According to this invention, A Rankine cycle thermodynamic system for converting thermal energy of a working fluid to mechanical energy in a cycle of evaporation, expansion, condensation, and compression, includes methylene chloride as the working fluid.
A system for performing the cycle of this invention includes a heat recovery boiler, an engine, a condenser, an open deaerating heater to receive condensate from the condenser, a boiler feed pump to receive working fluid from the deaerator and return it to the boiler, and a recuperative feed heater between engine and condenser to receive vapor from the engine and working fluid from the boiler feed pump en route to the boiler. The temperature differential between working fluid and heat source is at its minimum where working fluid enters the economizer section of the boiler and the waste heat medium leaves the economizer. The mass flow rate ratio of working fluid to waste heat medium is in the range from 0.5 to >1.
REFERENCES:
patent: 4424677 (1984-01-01), Likasavage
patent: 4558228 (1985-12-01), Larjola
patent: 4961311 (1990-10-01), Pave et al.
patent: 5490386 (1996-02-01), Keller et al.
patent: 5603218 (1997-02-01), Hooper
patent: 6041604 (2000-03-01), Nicodemus
Foster-Pegg, “Steam Bottoming Plants for Combined Cycles”, pp. 203-211, Apr. 1978.*
El-Wakil, “Powerplant technology”, pp. 31-35, 342-350, 1984.*
El-Sayed et al, “A Theoretical Comparison of the Rankine and Kalina cycles”, pp. 97-102, Nov. 1985.*
V. Ganapathy, “Waste Heat Boiler Deskbook”, pp. 205-213, 1991.*
Mainord et al, “Thermal Decomposition Studies on Methylene Chloride from 450 to 850 F”, pp. 1-6, Sep. 1999.
Bird Robert J.
Helios Energy Technologies, Inc.
Nguyen Hoang
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