Rankine cycle and working fluid therefor

• US 6,041,604 A
• Filed: 07/14/1998
• Issued: 03/28/2000
• Est. Priority Date: 07/14/1998
• Status: Expired due to Fees

• Current Assignee: Helios Research Corporation
• Original Assignee: Helios Research Corporation
• Inventors: Nicodemus, Mark
• Primary Examiner(s): Kamen, Noah P.
• Application Number:
  US09/115,347
• Time in Patent Office: 623 Days
• Field of Search: 60/651, 60/671, 60/657
• US Class Current: 60/671
• CPC Class Codes: F01K 25/08 using special vapours

Abstract

A thermodynamic cycle 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 includes a heat recovery boiler; an engine; a condenser; an open deaerating heater to receive condensate from the condenser; a heat exchanger to receive working fluid from the deaerating heater and condensate from the condenser en route to the deaerating heater; a boiler feed pump to receive working fluid from the heat exchanger 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.

Claims

1. A combined cycle thermodynamic system for transferring heat from the exhaust gas of a gas turbine topping cycle to a working fluid, and converting said heat to mechanical energy in a bottoming Rankine cycle, said system including, in a closed cycle forming a working fluid path:

a boiler with economizer and vaporizer sections to transfer heat from said exhaust gas to said working fluid;

means to convey said exhaust gas at a mass flow rate FHM in a first direction through said vaporizer and economizer sections of said boiler;

means to convey said working fluid at a mass flow rate WF along said working fluid path, counter to said first direction, through said economizer and vaporizer sections of said boiler to heat said working fluid in said economizer section and vaporize said working fluid in said vaporizer section;

a heat engine to expand said vaporized working fluid and convert thermal energy thereof to mechanical energy;

a condenser to condense said working fluid;

a condensate pump to recirculate said condensed working fluid back to said boiler;

an open deaerating heater disposed to receive working fluid condensate from said condenser, a heat exchanger disposed to receive said working fluid from said deaerating heater and working fluid condensate from said condenser en route to said deaerating heater, and a boiler feed pump disposed to receive working fluid from said heat exchanger and return it to said boiler, whereby working fluid intake to said boiler feed pump is deaerated and subcooled liquid;

a recuperative feed heater disposed between said engine and said condenser to receive working fluid exhaust vapor from said engine, and to receive liquid working fluid from said boiler feed pump en route to said boiler;

the ratio of mass flow rate WF of said working fluid to mass flow rate FHM of said exhaust gas being in the range from 0.5 to >

1, whereby the temperature differential between said exhaust gas and said working fluid is at minimum where said working fluid enters said economizer section and said exhaust gas leaves said economizer section;

said working fluid possessing peculiar thermophysical properties such that upon leaving said boiler it is thermodynamically capable, in an ideal isentropic expansion process, of yielding a total isentropic enthalpy drop of 75% or more of the available energy of said fluid heat medium as determined by second-law analysis.

2. A thermodynamic system as defined in claim 1, said deaerating heater being disposed also to receive working fluid vapor extracted from said engine.

3. A thermodynamic system as defined in claim 1, wherein said working fluid is substantially methylene chloride.