SYSTEM AND METHOD FOR GENERATION OF ELECTRICITY AND POWER FROM WASTE HEAT AND SOLAR SOURCES

• US 20050183421A1
• Filed: 02/24/2003
• Published: 08/25/2005
• Est. Priority Date: 02/25/2002
• Status: Active Grant

• Current Assignee: Outfitter Energy Incorporated
• Original Assignee: Kirell, Inc.
• Inventors: Azevedo, Richard A., Horn, Ralf, Vaynberg, Mikhail, Weiland, Alfons, Horn, Hans Gunter
• Granted Patent: US 6,981,377 B2
• Time in Patent Office: Days
• US Class Current: 60/641.800
• CPC Class Codes: F01K 25/08 using special vapours
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]

Abstract

Recovery of electric power from low-grade waste heat/solar energy, comprising a closed-cycle charged refrigerant loop. Pressurized refrigerant fluid is pumped at ambient temperature through a heat exchanger connected to a waste heat/solar source to extract heat energy during conversion to a high pressure gas. Heated/pressurized refrigerant gas is inlet into an expander to power an output shaft during the expansion of the fluid to a cooled gas at approximately 0 psig. Cooled gaseous refrigerant is condensed to a liquid at low pressure and ambient temperature, and recycled under pressure to the heat exchanger. The expander is a reverse-plumbed gas compressor; the pressurized, hot refrigerant gas is inlet at what is ordinarily its outlet, and the normal inlet becomes the expander end. The refrigerant gas mass flow pressure/temperature drop spins the expander shaft for direct mechanical power take-off, or coupling to a synchronous or inductive generator to produce electricity.

Claims

1. System for generation of electricity from waste heat and solar sources, comprising in operative combination:

a) a closed loop, refrigerant working fluid circuit comprising;

i) at least one heat exchanger providing heat energy from a waste heat or solar source to convert said working fluid from a liquid pressurized refrigerant to a heated gas refrigerant under pressure;

ii) an expander driven by said heated, pressurized refrigerant working fluid to produce power to an output shaft, said working fluid pressure being thereby reduced, and said expander comprises a screw compressor that is oriented to run in reverse in said circuit so that said refrigerant working fluid drives said output shaft while dropping in temperature, and wherein said expander is selected from a continuous and a multi-stage screw compressor;

iii) a generator driven by said screw compressor output shaft to produce electricity, said generator is selected from an induction-type generator and a synchronous-type generator;

iv) a condenser for reducing said lowered pressure refrigerant working fluid gas temperature thereby converting the working fluid gas to a liquid at the condensation temperature or below of said working fluid;

v) a pump for pressurizing and circulating said refrigerant working fluid in said circuit, said pump is driven by a variable frequency drive; and

vi) conduits interconnecting said heat exchanger, said expander, said condenser and said pump in a closed loop refrigerant circuit, said working fluid is selected from R123, 245FA, R134A, R22, and the like organic refrigerants, and said circuit includes an emergency refrigerant working fluid has bypass around said expander; and

b) a controller for monitoring said generator and selected temperatures and pressures of the refrigerant working fluid in pressurized liquid or gas form in said circuit, and for providing control signals to control said pump variable frequency drive, screw compressor and generator.

4. System as in claim 1 wherein said screw compress- or includes oil-lubricated bearings in the case of a dry screw compressor, and a secondary lube oil separation and recycle loop in the case of an oil lubricated compressor screws.

5. System as in claim 1 wherein said working fluid circuit includes a filter on the outlet side of said expander.

6. System as in claim 1 wherein said heat exchanger is multi-stage.

8. System as in claim 1 wherein said circuit includes a receiver downstream of said condenser to provide a reservoir for said cooled fluid refrigerant and a head for said working fluid pump.

9. System as in claim 8 wherein said condenser is cooled by a water-cooled heat exchanger comprising at least one of a cooling tower and a cooling water sump system.

10. System as in claim 1 wherein said controller includes a PLC having at least one control loop, temperature and pressure inputs representing measurements of actual expander input pressure and temperature and expander outlet temperature generator rpm and power monitoring condenser control, output to sad variable frequency drive, a program including pre-selected expander input temperature, pressure and Δ

T, and outputs for control of pump on/off, bypass valve control, and generator on/off-line control.

18. System as in claim 1 wherein said expander, generator, condenser, pump and refrigerant fluid circuit conduit components are mounted on a portable skid.

19. System as in claim 18 wherein said waste heat supplied by said heat exchanger is low grade waste heat.

20. System as in claim 1 wherein the refrigerant pressure input into said expander is below about 150 psig, and the refrigerant gas pressure out of said expander is up to about 5″

vacuum.

2. (canceled)

3. (canceled)

7. (canceled)

11. System for generation of electricity or direct shaft power from waste heat and solar sources, comprising in operative combination:

a) a portable skid, on which are mounted a closed, refrigerant working fluid circuit comprising;

i) input and output pressurized refrigerant conduits for connection to at least one heat exchanger providing heat energy from a low grade waste heat or solar source to convent said refrigerant working fluid from a liquid to a heated gas under pressure;

ii) an expander driven by said heated, pressurized refrigerant working fluid to produce power to an output shaft, said working fluid pressure being thereby reduced, and said expander comprises a screw compressor oriented to run in reverse in said circuit so that said refrigerant working fluid, during drop in pressure while passing through said compressor, drives said output shaft;

iii) said output shaft is coupled to at least one of an induction or synchronous-type generator to produce electricity and a direct power take off coupleable to a load to do work;

iv) a condenser for reducing said lowered pressure refrigerant working fluid gas temperature thereby converting the refrigerant working fluid gas to a liquid at the condensation temperature or below of said working fluid;

vii) a pump for pressurizing and circulating said refrigerant working fluid in said circuit, said pump is driven by a variable frequency drive; and

viii) conduits interconnecting said heat exchanger input and output, said ex-pander, said condenser and said pump in a closed loop circuit, said working fluid is selected from R123, 245FA, R134A, R22, and the like organic refrigerants, and said circuit includes an emergency refrigerant working fluid gas bypass around said expander; and

b) a controller for monitoring said output shaft and selected temperatures and pressures of the refrigerant working fluid in liquid or gas form in said circuit and for providing control signals to control said pump variable frequency drive and thereby the output of said shaft.

12. Method of generation of direct shaft power or electricity from waste heat or solar sources, comprising the steps in operative sequence of:

a) providing a waste heat source to a pressurized liquid refrigerant working fluid to heat said working fluid to a higher temperature, pressurized gas, said working fluid is selected from R123, 245FA, R134A, R22, and the like organic refrigerants;

b) pumping said refrigerant in a closed refrigerant working fluid loop circuit said pump being driven with a variable frequency drive;

c) driving an expander having an output shaft with said heated, pressurized gas thereby reducing the pressure of said gas, said expander comprising a screw compressor that is oriented to run in reverse in said circuit so that said refrigerant working fluid drives said output shaft while dropping in temperature and pressure;

d) driving at least one of a synchronous or induction generator to produce electricity or a power take off with said output shaft;

e) condensing said refrigerant working fluid gas to a liquid at its condensation temperature, or below;

f) recycling said refrigerant working fluid liquid under pressure to said waste heat source in a closed working fluid circuit; and

g) monitoring and controlling the flow, pressures and temperatures of said working fluid liquid and gas in said circuit to generate electricity or direct power from said expander output shaft, said monitoring and control steps include monitoring said shaft and selected temperatures and pressures of the working fluid in liquid or pas form in said circuit and for providing control signals to control said pump variable frequency drive, said condenser and said generator.

13. Method as in claim 12 wherein said circuit includes an emergency refrigerant working fluid gas bypass around said expander, and said recycle step comprises pumping said liquid refrigerant working fluid under pressure through a heat exchanger to obtain heat from said waste heat source.

16. Method as in claim 12 wherein said monitoring and control steps include providing a PLC having at least one control loop, temperature and pressure inputs representing measurements of actual expander input pressure and temperature and expander outlet temperature, generator or expander output shaft rpm and power monitoring, control of cooling of said expander output gas to a liquid, output to said variable frequency drive, a program including pre-selected expander input temperature, pressure and Δ

T, and outputs for control of pump on/off, control of valves and control of generator on/off-line status.

14. (canceled)

15. (canceled)

17. Method of generation of direct shaft power or electricity from waste heat or solar sources, comprising the steps in operative sequence of:

a) providing a waste heat source to a liquid working fluid to heat said working fluid to a higher temperature, pressurized gas;

b) driving an expander having an output shaft with said heated, pressurized gas thereby reducing the pressure of said gas, and said expander comprises a screw compressor oriented in reverse in said circuit so that said working fluid gas drives said compressor output shaft;

c) condensing said working fluid gas to a liquid at its condensation temperature, or below;

d) recycling said working fluid liquid to said waste heat source in a closed working fluid circuit, said recycling comprises pumping with a controllable variable frequency drive said liquid working fluid under pressure through a heat exchanger to obtain heat from said waste heat source; and

e) monitoring and controlling the pressures and temperatures of said working fluid liquid and gas in said circuit to generate electricity or direct power from said expander output shaft, said monitoring and controlling include monitoring said expander output shaft and selected temperatures and pressures of the working fluid in liquid or gas form in said circuit and providing control signals to control said pump, expander and generator, including providing a PLC having at least one control loop, temperature and pressure inputs representing measurements of actual expander input pressure and temperature and expander outlet temperature, generator or expander output shaft rpm and power monitoring, control of cooling of said expander output gas to a liquid, output to said variable frequency drive, a program including pre-selected expander input temperature, pressure and Δ

T, and outputs for control of pump on/off, control of valves and control of generator on/off-line status.