Combined cooling, heating and power system

Abstract

A combined cooling, heating and power system is formed by integrating a CO.sub.2 cycle subsystem, an ORC cycle subsystem, and an LNG cold energy utilization subsystem based on an SOFC/GT hybrid power generation subsystem. The combined system can achieve efficient and cascade utilization of energy and low carbon dioxide emission. An SOFC/GT hybrid system is used as a prime mover. High-, medium-, and low-temperature waste heat of the system are recovered through CO.sub.2 and ORC cycles, respectively. Cold energy (for air conditioning and refrigeration), heat, power, natural gas, ice, and dry ice can be provided by using LNG as a cold source of the CO.sub.2 and ORC cycles. Low CO.sub.2 emission is achieved by condensation and separation of CO.sub.2 from flue gas, so energy loss of the system can be reduced, and efficient and cascade utilization of energy can be achieved, thereby realizing energy conservation and emission reduction.

Claims

1. A combined cooling, heating and power system based on solid oxide fuel cell (SOFC) and gas turbine (GT) and CO2 (SOFC/GT/CO2) and organic Rankine cycle (ORC) combined cycle power generation and liquefied natural gas (LNG) cold energy utilization, comprising: an SOFC/GT hybrid power generation subsystem, a CO2 cycle subsystem, an ORC cycle subsystem, an LNG cold energy utilization subsystem, a heating subsystem, and a CO2 capture and air conditioning cooling subsystem, wherein the CO2 cycle subsystem comprises a supercritical CO2 (SCO2) cycle and a transcritical CO2 (TCO2) cycle; the SCO2 cycle comprises a waste heat boiler, a first electric generator, an SCO2 turbine, a gas cooler, and an SCO2 compressor; the waste heat boiler is configured to receive an exhaust from a first preheater of the SOFC/GT hybrid power generation subsystem to heat a first working fluid CO2 in the SCO2 cycle and produce a flue gas; in the SCO2 cycle, the SCO2 turbine is configured to receive the first working fluid CO2 in the SCO2 cycle that has been heated by the waste heat boiler and do work to drive the first electric generator to generate electricity; the gas cooler is configured to receive the first working fluid CO2 from the SCO2 turbine to heat a second working fluid CO2 in the TCO2 cycle; the SCO2 compressor is configured to receive the first working fluid CO2 from the gas cooler in the SCO2 cycle for compression; the waste heat boiler is configured to receive the first working fluid CO2 discharged from the SCO2 compressor for reheating so that one supercritical CO2 cycle is completed; the CO2 capture and air conditioning cooling subsystem comprises an evaporator, a first separator, a first air conditioning cooler, a first heat exchanger, a second separator, a dry ice container, a first condenser, a second heat exchanger, a second air conditioning cooler, and a first ice container; the evaporator is configured to receive the flue gas from the waste heat boiler; the first separator is configured to: receive the flue gas discharged from a flue gas side of the evaporator, and separate a first flow of water from the flue gas; the first air conditioning cooler is configured to receive the first flow of water to provide cooling for users; the first heat exchanger is configured to: receive the flue gas from the first separator, cool the flue gas by a working fluid R1150, and condense a CO2 gas in the flue gas into dry ice; the second separator is configured to: receive the flue gas discharged from the first heat exchanger, and separate the flue gas from the dry ice; the dry ice container is configured to store the dry ice; and the first condenser is configured to receive the flue gas discharged from the second separator to condense the second working fluid CO2 in the TCO2 cycle.

2. The combined cooling, heating and power system according to claim 1, wherein the SOFC/GT hybrid power generation subsystem comprises an air compressor, the first preheater, an SOFC, a second preheater, a water pump, a third preheater, a mixer, an inverter, an afterburner, a gas turbine, and a second electric generator, wherein the air compressor and the third preheater are connected in series and then are connected to a cathode of the SOFC; the water pump is connected to the first preheater, the first preheater and the second preheater are connected to the mixer, and the mixer is connected to an anode of the SOFC; the SOFC is connected to the inverter to convert direct current to alternating current; the afterburner is configured to receive an exhaust from the cathode and an exhaust from the anode of the SOFC; the gas turbine is configured to receive a high-temperature exhaust from the afterburner such that the high-temperature exhaust expands through the gas turbine to do work to drive the second electric generator to generate electricity; and the third preheater, the second preheater, and the first preheater are configured to receive an exhaust from the gas turbine in sequence to preheat air, fuel, and a second flow of water, respectively.

3. The combined cooling, heating and power system according to claim 1, wherein the TCO.sub.2 cycle comprises the gas cooler, a TCO.sub.2 turbine a second electric generator, the first condenser, a second condenser, a third condenser, a working fluid CO.sub.2 pump, and a precooler; the gas cooler is configured to heat the second working fluid CO.sub.2 in the TCO.sub.2 cycle; the TCO.sub.2 turbine is configured to receive the second working fluid CO.sub.2 in the TCO.sub.2 cycle that has been heated by the gas cooler and do work to drive the second electric generator to generate electricity; the first condenser, the second condenser, and the third condenser are configured to condense an exhaust discharged from the TCO.sub.2 turbine; the first condenser, the second condenser, and the third condenser are connected to the working fluid CO.sub.2 pump, and the precooler is configured to receive the second working fluid CO.sub.2 in the TCO.sub.2 cycle that is discharged from an outlet of the working fluid CO.sub.2 pump and cool a low-temperature cold store; and the gas cooler is configured to receive the second working fluid CO.sub.2 in the TCO.sub.2 cycle that is discharged from an outlet of the precooler and heat the second working fluid CO.sub.2 in the TCO.sub.2 cycle by the first working fluid CO.sub.2 in the SCO.sub.2 cycle, so that one transcritical CO.sub.2 cycle is completed.

4. The combined cooling, heating and power system according to claim 1, wherein the heating subsystem comprises a third heat exchanger disposed between the waste heat boiler and the evaporator; and the third heat exchanger is configured to receive the flue gas discharged from the waste heat boiler to provide heating for users.

5. The combined cooling, heating and power system according to claim 1, wherein the working fluid R1150 is used in the ORC cycle subsystem; the ORC cycle subsystem comprises a third heat exchanger, the evaporator, an R1150 turbine, a second electric generator, an R1150 condenser, a working fluid R1150 pump, and the first heat exchanger; the third heat exchanger disposed between the waste heat boiler, and the evaporator; the evaporator is configured to receive the flue gas discharged from an outlet of the third heat exchanger to heat the working fluid R1150 in the ORC cycle; the R1150 turbine is configured to receive the working fluid R1150 discharged from an outlet at a working fluid R1150 side of the evaporator and do work to drive the second electric generator to generate electricity; the R1150 condenser is configured to condense an exhaust discharged from the R1150 turbine; the R1150 condenser is connected to the working fluid R1150 pump, and the first heat exchanger is configured to receive the working fluid R1150 discharged from the working fluid R1150 pump; and the evaporator is configured to receive the working fluid R1150 discharged from the first heat exchanger to heat and evaporate the working fluid R1150, so that one working fluid R1150 cycle is completed.

6. The combined cooling, heating and power system according to claim 1, wherein the second heat exchanger is configured to receive the flue gas discharged from the first condenser and condense a second flow of water to generate ice; and the first ice container is configured to store the ice; and the second air conditioning cooler is configured to: receive the flue gas discharged from the second heat exchanger to produce cooling, and discharge the flue gas into the atmosphere.

7. The combined cooling, heating and power system according to claim 1, wherein the LNG cold energy utilization subsystem comprises an LNG tank, an LNG pump, an R1150 condenser, a second condenser, a third condenser, a third heat exchanger, a second ice container, and a third air conditioning cooler; the LNG tank is connected to the LNG pump, the LNG cold energy utilization subsystem is configured to: (i) divide LNG from an outlet of the LNG pump into a first part and a second part such that: the first part enters the R1150 condenser and the third condenser in sequence, and is reverted to a first natural gas by absorbing heat in the R1150 condenser and the third condenser, and the second part enters the second condenser and is reverted to a second natural gas by absorbing heal in the second condenser; and (ii) merge the first natural gas from the first part and the second natural gas from the second part to form a merged natural gas after the first natural gas from the first part flows out of the third condenser and the second natural gas from the second part flows out of the second condenser; the third heat exchanger is configured to receive the merged natural gas and form ice by condensing a second flow of water; the second ice container is configured to store the ice; the third air conditioning cooler is configured to receive the merged natural gas discharged from the third heat exchanger to produce cooling; and the combined cooling, heating and power system is configured to: feed a part of the merged natural gas discharged from the third air conditioning cooler into a second preheater as a fuel of an SOFC for preheating, and supply a remaining part of the merged natural gas discharged from the third air conditioning cooler to a gas network.

8. The combined cooling, heating and power system according to claim 1, wherein the dry ice container is capable of providing the dry ice to users, the second heat exchanger and a third heat exchanger are configured to store cold energy by making a first ice and a second ice, respectively, and the first ice container and a second ice container are configured to store the first ice and the second ice, respectively, so that the first ice and the second ice can be provided to users.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings of the specification forming a part of the present application are used to further understand the present application. Exemplary embodiments of the present application and descriptions thereof are used to explain the present application, and do not constitute an improper limitation of the application.

(2) FIG. 1 is a schematic diagram of constitution of a combined cooling, heating and power system based on SOFC/GT/CO.sub.2 and ORC combined cycle power generation and LNG cold energy utilization.

(3) 1. Air compressor; 2. SOFC; 3. afterburner; 4. gas turbine; 5. first preheater; 6. second preheater; 7. water pump; 8. third preheater; 9. mixer; 10. waste heat boiler; 11. SCO.sub.2 turbine; 12. gas cooler; 13. SCO.sub.2 compressor; 14. TCO.sub.2 turbine; 15. first condenser; 16. second condenser; 17. third condenser; 18. working fluid CO.sub.2 pump; 19. precooler; 20. first heat exchanger; 21. evaporator; 22. R1150 turbine; 23. R1150 condenser; 24. working fluid R1150 pump; 25. second heat exchanger; 26. first separator; 27. first air conditioning cooler; 28. second separator; 29. dry ice container; 30. LNG tank; 31. LNG pump; 32. fourth heat exchanger; 33. third air conditioning cooler; 34. second ice container; 35. third heat exchanger; 36. second air conditioning cooler; 37. first ice container; 38. inverter; 39. first electric generator; 40. second electric generator; 41. third electric generator; 42. fourth electric generator

DETAILED DESCRIPTION

(4) It is to be noted that the following detailed descriptions are all exemplary and are intended to provide a further understanding of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs.

(5) It should be noted that terms used herein are only for the purpose of describing specific implementations and are not intended to limit the exemplary implementations of this application. As used herein, the singular form is also intended to include the plural form unless the context clearly dictates otherwise. In addition, it should be further understood that, terms “comprise” and/or “include” used in this specification indicate that there are features, steps, operations, devices, components, and/or combinations thereof.

(6) As shown in FIG. 1, an air compressor 1 and a first preheater 5 are connected in series and then connected to the cathode of an SOFC 2.

(7) A water pump 7 is connected to a third preheater 8, a second preheater 6 and the third preheater 8 are connected to a mixer 9, and the mixer 9 is connected to the anode of the SOFC 2.

(8) An SOFC 2 stack is connected to an inverter 38 to convert direct current to alternating current. Exhaust from the cathode and exhaust from the anode of the SOFC 2 enters an afterburner 3.

(9) High-temperature exhaust from the afterburner 3 enters a gas turbine 4 to do work to drive an electric generator to generate electricity.

(10) Exhaust from the gas turbine 4 enters the first preheater 5, the second preheater 6, and the third preheater 8 in sequence to preheat air, fuel, and water, respectively.

(11) Exhaust from the third preheater 8 enters a waste heat boiler 10 to heat working fluid CO.sub.2. The heated working fluid CO.sub.2 enters an SCO.sub.2 turbine 11 of a supercritical CO.sub.2 cycle (SCO.sub.2 cycle) to do work to drive the electric generator to generate electricity. Exhaust from the SCO.sub.2 turbine 11 enters a gas cooler 12 to heat the working fluid CO.sub.2 in a transcritical CO.sub.2 cycle (TCO.sub.2 cycle). Exhaust from the gas cooler 12 in the SCO.sub.2 cycle enters an SCO.sub.2 compressor 13 for compression and is then fed into the waste heat boiler 10 for reheating, thus completing a supercritical CO.sub.2 cycle.

(12) A working fluid CO.sub.2 in the TCO.sub.2 cycle is heated in the gas cooler 12 and enters the TCO.sub.2 turbine 14 to do work to drive the electric generator to generate electricity. Exhaust from the TCO.sub.2 turbine 14 is condensed in a first condenser 15, a second condenser 16, and a third condenser 17. The first condenser 15, the second condenser 16, and the third condenser 17 are connected to a working fluid CO.sub.2 pump 18, and the working fluid CO.sub.2 from the outlet of the working fluid CO.sub.2 pump 18 enters a precooler 19 to cool a low-temperature cold store. The working fluid CO.sub.2 from the outlet of the precooler 19 enters the gas cooler 12 and is heated by the working fluid CO.sub.2 in the SCO.sub.2 cycle, so that one transcritical CO.sub.2 cycle is completed.

(13) Flue gas from the outlet of the waste heat boiler 10 enters a first heat exchanger 20 to heat the outside.

(14) Flue gas from the outlet of the first heat exchanger 20 enters an evaporator 21 to heat working fluid R1150 in the ORC cycle. The working fluid R1150 from the outlet of the evaporator 21 enters an R1150 turbine 22 to do work to drive an electric generator to generate electricity. Exhaust from the R1150 turbine 22 is condensed in an R1150 condenser 23. The R1150 condenser 23 is connected to a working fluid R1150 pump 24, and the working fluid R1150 from the outlet of the working fluid R1150 pump 24 enters a second heat exchanger 25 for heating. The working fluid R1150 discharged from the second heat exchanger 25 enters the evaporator 21 to absorb heat and evaporate, so that one working fluid R1150 cycle is completed.

(15) Flue gas from the outlet of the evaporator 21 enters a first separator 26, flue gas is separated from water in the first separator 26, water enters a first air conditioning cooler 27 to cool the outside, the flue gas enters the second heat exchanger 25 to be cooled by the working fluid R1150, and the CO.sub.2 gas is condensed into dry ice.

(16) Flue gas from the outlet of the second heat exchanger 25 enters a second separator 28, the flue gas is separated from the dry ice in the second separator 28, the dry ice is stored in a dry ice container 29, and the flue gas enters the third condenser 17 to condense the working fluid CO.sub.2.

(17) Flue gas from the outlet of the third condenser 17 enters a third heat exchanger 35 to condense the water, and ice formed is stored in a first ice container 37. Flue gas from the outlet of the third heat exchanger 35 enters a second air conditioning cooler 36 to cool the outside and is then discharged into the atmosphere.

(18) An LNG tank 30 is connected to an LNG pump 31. LNG from the outlet of the LNG pump 31 is divided into two parts: one part enters the R1150 condenser 23 and the first condenser 15 in sequence, and the other part enters the second condenser 16. The two parts of natural gas merge after flowing out of the outlet of the first condenser 15 and the outlet of the second condenser 16, respectively, and enter a fourth heat exchanger 32 to condense water, and ice formed is stored in a second ice container 34. Natural gas from the outlet of the fourth heat exchanger 32 enters a third air conditioning cooler 33 to cool the outside. A part of natural gas from the outlet of the third air conditioning cooler 33 is fed into a second preheater 6 as a fuel for preheating, and the remaining part of natural gas is supplied to a gas network.

(19) Initial conditions and system simulation results of a combined cooling, heating and power system based on SOFC/GT/CO.sub.2 and ORC combined cycle power generation and LNG cold energy utilization are shown in Table 1 and Table 2, respectively.

(20) TABLE-US-00001 TABLE 1 Initial conditions of a system Item Value Item Value Air flow rate 6.618 mol/s Inlet pressure of an SCO.sub.2 20 MPa turbine Fuel flow rate 0.514 mol/s Outlet pressure of the SCO.sub.2 7.4 MPa turbine Ambient pressure 0.101325 MPa Inlet pressure of a TCO.sub.2 20 MPa turbine Ambient temperature 298.15 K Outlet pressure of the TCO.sub.2 1.4 MPa turbine Pressure ratio of a 9 Outlet temperature of a 225.15 K water pump TCO.sub.2 condenser Pressure ratio of an 9 LNG temperature 111.68 K air compressor Adiabatic internal 0.75 LNG pressure 0.16968 MPa efficiency of the air compressor Steam/carbon ratio 2 Isentropic efficiency of the 0.9 SCO.sub.2 turbine Fuel utilization 0.85 Isentropic efficiency of the 0.85 TCO.sub.2 turbine Temperature of SOFC 700 K Isentropic efficiency of an 0.89 inlet SCO.sub.2 compressor An area of a single 0.027 m.sup.2 Adiabatic internal 0.8 cell of the SOFC efficiency of a TCO.sub.2 pump A number of single 5000 Outlet pressure of an R1150 0.11 MPa cells of the SOFC turbine Efficiency of an 0.98 Outlet temperature of an 170.15 K inverter R1150 condenser Heat transfer temperature 10 K Isentropic efficiency of the 0.89 difference of a waste R1150 turbine heat boiler Inlet temperature of 295.15 K Adiabatic internal 0.8 the SCO.sub.2 compressor efficiency of an R1150 pump

(21) TABLE-US-00002 TABLE 2 System simulation result Parameter Value Working voltage of an SOFC 0.6653 V Working temperature of the SOFC 1142 K Electric generation of the SOFC 211.000 kW Electric generation of a gas turbine 126.934 kW Electric generation of an SCO.sub.2 turbine 17.702 kW Electric generation of a TCO.sub.2 turbine 19.739 kW Electric generation of an R1150 turbine 26.426 kW Net electric generation of a system 331.280 kW Cold energy capacity of dry ice 14.987 kW Cold energy capacity of ice 14.692 kW Cold energy capacity of a low-temperature cold store 20.360 kW Cold energy capacity of an air conditioning 11.066 kW Supplied heat 58.563 kW Supply of natural gas to the outside 8.594 mol/s Reduced CO.sub.2 emission 0.514 mol/s Power generation efficiency of the SOFC 51.24% Comprehensive energy efficiency of the system 82.79% Net power generation efficiency of the system 80.45% Total exergy efficiency of the system 63.21%

(22) It may be known from Table 2 that under rated conditions, the net power generation efficiency of the system of the present invention is 80.45%, the comprehensive energy utilization rate of the system is 82.79%, the total exergy efficiency of the system is 63.21%, the net electric generation of the system is 331.280 kW, the cold energy capacity for low-temperature cold store is 20.360 kW, the cold energy capacity for air conditioning is 11.066 kW, the supplied heat is 58.563 kW, the cold energy capacity of the dry ice is 14.987 kW, the cold energy capacity of the ice is 14.692 kW, supply of natural gas to the outside is 8.594 mol/s, and the reduced CO2 emission is 0.514 mol/s, achieving efficient and cascade utilization of the energy and low carbon emission. If the system runs 5000 hours/year, 407.088 tons of emitted CO.sub.2 may be reduced per year.

(23) The foregoing descriptions are merely exemplary embodiments of this application but are not intended to limit this application. This application may include various modifications and changes for a person skilled in the art. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of this application shall fall within the protection scope of this application.