Methanol fuel ship hybrid power system coupled with carbon dioxide in-situ capture and utilization

Abstract

The invention discloses a methanol fuel ship hybrid power system coupled with carbon dioxide in-situ capture and utilization. The methanol fuel ship hybrid power system comprises an SOFC / GT system, a supercritical carbon dioxide cycle power generation system, an organic Rankine cycle power generation system and a carbon dioxide in-situ utilization system. Exhaust gas of a gas turbine in the SOFC / GT system serves as a heat source to be sequentially used for heating cycle working media of the supercritical carbon dioxide cycle power generation system and the organic Rankine cycle power generation system and then enters the carbon dioxide in-situ utilization system. Exhaust gas received by the carbon dioxide in-situ utilization system is condensed through a condenser to separate H2O and then enters a cathode of the porous solid electrolytic cell, the cathode comprises a KOH solution and an anion exchange membrane, an anode comprises water and a cation exchange membrane, an electrode catalyst is bismuth oxide, anode exhaust gas enters the SOFC / GT system, and formic acid discharged by a middle interlayer enters a formic acid storage tank. According to the invention, the carbon dioxide in the waste gas is captured in situ on the methanol fuel ship to generate a high-added-value product, and the energy of a power system is comprehensively utilized.

Description

Technical Field

[0001] The present invention relates to a hybrid power system for ships, in particular to a methanol fuel hybrid power system for ships coupled with in-situ capture and utilization of carbon dioxide. Background Art

[0002] Ships using SOFC (solid oxide fuel cell) as power equipment and methanol as fuel do not release cold energy like LNG fuel. Therefore, during the CO2 collection process using a liquefaction method, such as the Chinese patent publication number CN102760900A, the captured CO2 is directly fed into the compressor of the 4-stage interstage cooler for compression, resulting in large energy losses. In addition, the CO2 capture and liquefaction process system is complex to arrange on board, which limits the application of carbon emission control on methanol-fueled ships.

[0003] The Chinese patent with publication number CN118775001A separates CO2 and exhaust gas through a membrane separation device and utilizes the heat of the exhaust gas through an organic Rankine cycle and heat absorption of the fuel, but still uses pressurized cooling to liquefy and store CO2. Summary of the Invention

[0004] In response to the above-mentioned defects in the prior art, the task of the present invention is to provide a methanol-fueled ship hybrid power system coupled with in-situ capture and utilization of carbon dioxide, with the aim of improving the energy utilization efficiency of the system while performing in-situ utilization of the CO2 emitted by the power system to achieve system energy conservation and emission reduction.

[0005] The technical solution of the present invention is as follows: a methanol-fueled ship hybrid system coupled with in-situ carbon dioxide capture and utilization, comprising a SOFC / GT system, a supercritical carbon dioxide cycle power generation system, an organic Rankine cycle power generation system, and a carbon dioxide in-situ utilization system;

[0006] The exhaust gas of the gas turbine in the SOFC / GT system is used as a heat source to heat the circulating working fluids of the supercritical carbon dioxide cycle power generation system and the organic Rankine cycle power generation system in sequence, and then enters the carbon dioxide in-situ utilization system;

[0007] The carbon dioxide in-situ utilization system includes a condenser, a porous solid electrolytic cell and a formic acid storage tank. The exhaust gas entering the carbon dioxide in-situ utilization system is condensed by the condenser to separate H2O and then enters the cathode of the porous solid electrolytic cell. The cathode of the porous solid electrolytic cell includes a KOH solution and an anion exchange membrane, the anode of the porous solid electrolytic cell includes water and a cation exchange membrane, and the electrode catalyst of the porous solid electrolytic cell is bismuth oxide. The anode exhaust gas of the porous solid electrolytic cell enters the SOFC / GT system, and the formic acid discharged from the middle partition of the porous solid electrolytic cell enters the formic acid storage tank.

[0008] Furthermore, the SOFC / GT system includes a reforming chamber and a first heat exchanger. Water and methanol enter the reforming chamber after passing through the first heat exchanger. After heating the circulating working fluid of the supercritical carbon dioxide cycle power generation system, the exhaust gas first passes through the first heat exchanger to heat the water and methanol and then heats the circulating working fluid of the organic Rankine cycle power generation system.

[0009] Furthermore, the circulating working fluid of the supercritical carbon dioxide cycle power generation system is heated by a heat exchanger before being cooled and compressed and before being expanded to do work in the organic Rankine cycle power generation system.

[0010] Furthermore, the organic Rankine cycle power generation system includes a third turbine, a fourth heat exchanger, a fourth turbine, a third cooler and a working fluid pump connected in sequence. The circulating working fluid pumped by the working fluid pump is heated by the circulating working fluid of the supercritical carbon dioxide cycle power generation system and then enters the third turbine to perform work. The circulating working fluid discharged from the third turbine is heated by the exhaust gas in the fourth heat exchanger and then enters the fourth turbine to perform work.

[0011] Furthermore, the supercritical carbon dioxide circulation power generation system includes a first-stage supercritical carbon dioxide circulation power generation system and a second-stage supercritical carbon dioxide circulation power generation system. The exhaust gas of the gas turbine in the SOFC / GT system sequentially heats the circulating working fluid of the first-stage supercritical carbon dioxide circulation power generation system and the second-stage supercritical carbon dioxide circulation power generation system. The circulating working fluid in the organic Rankine cycle power generation system before expansion and work is heated by the circulating working fluid of the first-stage supercritical carbon dioxide circulation power generation system and the circulating working fluid of the second-stage supercritical carbon dioxide circulation power generation system in sequence.

[0012] Furthermore, the first-stage supercritical carbon dioxide cycle power generation system includes a sixth heat exchanger, a first cooler, a first CO2 compressor, a fifth heat exchanger, a second heat exchanger and a first turbine. The circulating working fluid discharged from the first turbine preheats the circulating working fluid compressed by the first CO2 compressor in the fifth heat exchanger, enters the sixth heat exchanger to preheat the organic working fluid in the organic Rankine cycle power generation system, and then enters the first cooler. The circulating working fluid preheated in the fifth heat exchanger is heated by the exhaust gas in the second heat exchanger and then enters the first turbine.

[0013] Furthermore, the second-stage supercritical carbon dioxide cycle power generation system includes an eighth heat exchanger, a second cooler, a second CO2 compressor, a seventh heat exchanger, a third heat exchanger and a second turbine. The circulating working fluid discharged from the second turbine preheats the circulating working fluid compressed by the second CO2 compressor in the seventh heat exchanger, enters the eighth heat exchanger to preheat the organic working fluid in the organic Rankine cycle power generation system, and then enters the second cooler. The circulating working fluid preheated in the seventh heat exchanger enters the second turbine after being heated by the exhaust gas in the third heat exchanger.

[0014] Furthermore, the anode of the porous solid electrolytic cell is connected to a second water pump, a fourth cooler and a water storage tank in sequence, the second water pump pumps the drainage of the anode of the porous solid electrolytic cell into the fourth cooler, and the water in the water storage tank is provided to the anode of the porous solid electrolytic cell.

[0015] Furthermore, N2 discharged from the cathode of the porous solid electrolytic cell is connected to the middle partition layer to flush the porous solid and discharge formic acid.

[0016] Furthermore, the electricity required for the operation of the carbon dioxide in-situ utilization system comes from the SOFC / GT system.

[0017] Compared with the prior art, the advantages of the technical solution of the present invention are:

[0018] (1) The present invention uses a porous solid electrolyzer to treat CO2 emitted by the SOFC / GT system. Through SOFC power distribution, it realizes the efficient in-situ capture and utilization of CO2 on board the ship and generates high-value-added product formic acid. Compared with complex CO2 capture and liquefaction equipment, the present invention makes the capture, conversion and storage of CO2 on board the ship simpler and more efficient.

[0019] (2) The present invention constructs a SOFC / GT main power system using methanol as fuel, and uses the GT exhaust to drive a two-stage SCO2 (supercritical carbon dioxide) cycle, preheat the reforming chamber inlet stream, and drive the ORC cycle (organic Rankine cycle), making full use of different heat sources of various grades; compared with traditional diesel engine main power systems that use heavy oil or diesel as fuel, the energy utilization efficiency is higher and the emissions are lower. The organic Rankine cycle is used to recover the heat in the two-stage SCO2 cycle, thereby improving the waste heat utilization efficiency.

[0020] (3) The present invention couples the CO2 in-situ utilization system and the SOFC / GT / SCO2 / ORC system. Through the rational distribution of electricity and waste heat, it not only enables the power system to achieve near-zero carbon emissions and the in-situ utilization rate of the emitted CO2 to reach more than 90%, but also realizes the efficient utilization of the energy system of the entire ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a methanol fuel ship hybrid power system coupled with in-situ capture and utilization of carbon dioxide according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the examples, but are not intended to limit the present invention.

[0023] Please combine Figure 1 As shown, the methanol fuel ship hybrid power system coupled with in-situ capture and utilization of carbon dioxide involved in an embodiment of the present invention includes a mixer 1, a first water pump 2, a first heat exchanger 3, a reforming chamber 4, an air compressor 5, an SOFC 6, an inverter 7, an afterburner 8, a gas turbine 9, a second heat exchanger 10, a third heat exchanger 11, a fourth heat exchanger 12, a first CO2 compressor 13, a fifth heat exchanger 14, a first turbine 15, a sixth heat exchanger 16, a first cooler 17, a second CO2 compressor 18, a seventh heat exchanger 19, a second turbine 20, an eighth heat exchanger 21, a second cooler 22, a working fluid pump 23, a third turbine 24, a fourth turbine 25, a third cooler 26, a condenser 27, a porous solid electrolyzer 28, a formic acid storage tank 29, a second water pump 30, a fourth cooler 31 and a water storage tank 32.

[0024] The connection of the above components respectively constitutes the SOFC / GT system, the supercritical carbon dioxide circulation power generation system, the organic Rankine cycle power generation system and the carbon dioxide in-situ utilization system, among which the supercritical carbon dioxide circulation power generation system includes the first-stage supercritical carbon dioxide circulation power generation system and the second-stage supercritical carbon dioxide circulation power generation system.

[0025] The SOFC / GT system includes a mixer 1, a first water pump 2, a first heat exchanger 3, a reforming chamber 4, an air compressor 5, an SOFC 6, an inverter 7, an afterburner 8, and a gas turbine 9. After methanol and water are mixed in the mixer 1, the resulting solution is compressed to the desired pressure using the first water pump 2. It is then preheated in the first heat exchanger 3 and passed into the reforming chamber 4, where a reforming reaction occurs, producing carbon monoxide and hydrogen streams.

[0026] The anode of fuel cell 6 receives the hydrogen-rich syngas produced by the reforming reaction. Air and oxygen, compressed by air compressor 5, enter the cathode of fuel cell 6, where they undergo an electrochemical reaction with the anode gas to generate electricity. The unreacted fuel gas is then introduced into combustion chamber 8 for combustion, generating a large amount of heat, which provides thermal energy for reforming reactor 4. The exhaust gas after combustion is then fed into gas turbine 9 for operation.

[0027] The first-stage supercritical carbon dioxide cycle power generation system includes a second heat exchanger 10, a first CO2 compressor 13, a fifth heat exchanger 14, a first turbine 15, a sixth heat exchanger 16, and a first cooler 17. The CO2 stream in this cycle power generation system is first compressed in the first CO2 compressor 13, then expanded and preheated in the fifth heat exchanger 14 after being expanded and worked. Heat from the exhaust gas of the gas turbine 9 is absorbed in the second heat exchanger 10, completing the heating process. The high-temperature, high-pressure CO2 stream then expands and works in the first turbine 15, preheating the CO2 stream in the fifth heat exchanger 14. Due to the pinch point problem of the heat exchanger, the hot stream outlet of the fifth heat exchanger 14 still has a very high temperature, so the organic working fluid of the organic Rankine cycle power generation system is preheated in the sixth heat exchanger 16. The final outflow stream enters the first cooler 17 for cooling, returning to its initial state, completing the first-stage supercritical carbon dioxide cycle.

[0028] The second-stage supercritical carbon dioxide power generation system includes a third heat exchanger 11, a second CO2 compressor 18, a seventh heat exchanger 19, a second turbine 20, an eighth heat exchanger 21, and a second cooler 22. The CO2 flow in this cycle power generation system is first compressed in the second CO2 compressor 18, and then the CO2 flow that has been expanded and performed work is preheated in the seventh heat exchanger 19. The heat of the exhaust gas of the gas turbine 9 after flowing through the first-stage supercritical carbon dioxide cycle power generation system in the third heat exchanger 11 completes the heating process. Subsequently, the high-temperature and high-pressure CO2 flow is expanded and performed work in the second turbine 20, and the CO2 flow is preheated in the seventh heat exchanger 19. Finally, the outflow stream is reheated in the eighth heat exchanger 21 to the organic working fluid of the organic Rankine cycle power generation system, and then enters the second cooler 22 for cooling, returning to the initial state, completing the second-stage supercritical carbon dioxide cycle.

[0029] The organic Rankine cycle power generation system includes a fourth heat exchanger 12, an eighth heat exchanger 21, a working fluid pump 23, a third turbine 24, a fourth turbine 25, and a third cooler 26. In this cycle power generation system, the organic working fluid is first pressurized by the working fluid pump 23. It is then preheated in the sixth heat exchanger 16 using heat from the first-stage supercritical CO2 cycle. It is then reheated in the eighth heat exchanger 21 using heat from the second-stage supercritical CO2 cycle, completing the first heating process. The exhaust gas then recovers heat from the gas turbine 9 after passing through the second-stage supercritical CO2 cycle power generation system in the fourth heat exchanger 12. The exhaust gas is then transferred to the fourth turbine 25 for expansion and work. Finally, the organic working fluid enters the third cooler 26 for cooling, returning to its initial state, completing the organic Rankine cycle.

[0030] The carbon dioxide in-situ utilization system includes a condenser 27, a porous solid electrolytic cell 28, a formic acid storage tank 29, a second water pump 30, a fourth cooler 31 and a water storage tank 32. The exhaust gas of the gas turbine 9 in the SOFC / GT system mainly contains H2O, CO2 and N2. A porous solid electrolytic cell 28 is used, in which the cathode is composed of a KOH solution and an anion exchange membrane (AEM), the anode is composed of water and a cation exchange membrane (CEM), and the electrode catalyst is bismuth oxide (Bi2O3). The exhaust gas of the gas turbine 9 after passing through the organic Rankine cycle power generation system is first separated by condensation in the condenser 27 before entering the porous solid electrolytic cell 28. Then, CO2 and N2 are passed into the cathode of the porous solid electrolytic cell 28 and absorbed by the KOH solution to produce CO3 2- , CO3 2- Anions pass through the anion exchange membrane and enter the middle barrier of the porous solid electrolytic cell 28. At the same time, the anode electrolysis of the porous solid electrolytic cell 28 produces H + and oxygen, passing through the proton exchange membrane into the middle barrier of the porous solid electrolytic cell 28. Then CO3 2- With H + The electrolysis reaction generates formic acid, which adheres to the porous solid surface of the intermediate layer. It is then flushed with nitrogen discharged from the cathode and collected as high-purity formic acid, which is stored in a formic acid storage tank 29. The oxygen generated at the anode can be used as input to the power system, forming an "air + oxygen" input.

[0031] The second water pump 30 outputs the water from the anode of the porous solid electrolytic cell 28, and then cools the output water in the fourth cooler 31 and stores it in the water storage tank 32. The low-temperature water in the water storage tank 32 is then input back into the anode of the porous solid electrolytic cell 28, thereby achieving the purpose of continuously exchanging heat between the inside of the porous solid electrolytic cell 28 and the outside world, and realizing continuous cooling of the porous solid electrolytic cell 28.

[0032] The following is a simulation example of a methanol-fueled ship hybrid system coupled with in-situ capture and utilization of carbon dioxide to verify the feasibility of the invention.

[0033] Table 1 System initial conditions

[0034] project Value project Value Methanol / water feed molar ratio 1:1 Environmental pressure 0.1MPa SOFC operating temperature 900℃ Turbine mechanical efficiency 0.98 SOFC fuel utilization 0.85 Turbine isentropic efficiency 0.85 SOFC operating pressure 0.8MPa Compressor mechanical efficiency 0.98 DA / AC conversion rate 0.97 Compressor isentropic efficiency 0.8 Ambient temperature 25℃ Pump efficiency 0.85

[0035] Table 2 System simulation results

[0036] project Value project Value SOFC voltage 0.467V ORC cycle power generation 237kW SOFC output power 6673kW System net power generation 10425kW GT work 2915kW Ship navigation consumption 6400kW <![CDATA[First-stage supercritical CO2 power cycle generation]]> 549kW <![CDATA[CO2 in-situ utilization system consumption]]> 4025kW <![CDATA[Second-level supercritical CO2 cycle power generation]]> 374kW System energy efficiency 64.83％

[0037] As shown in Table 2, this system, designed for large ocean-going asphalt carriers, can achieve a net power generation output of 10,425 kW and a net power generation efficiency of 64.83%, significantly improving system energy efficiency. Furthermore, it can achieve in-situ utilization of over 90% of the CO2 emitted by the power system, achieving near-zero carbon emissions for the vessel. If the system operates 300 days per year, the resulting emissions reduction is 29,995 tons of CO2 per year, representing significant emissions reduction potential.

Claims

1. A methanol fuel ship hybrid system coupled with in-situ carbon dioxide capture and utilization, characterized in that: Including SOFC / GT system, supercritical carbon dioxide cycle power generation system, organic Rankine cycle power generation system and carbon dioxide in-situ utilization system; The exhaust gas of the gas turbine in the SOFC / GT system is used as a heat source to heat the circulating working fluids of the supercritical carbon dioxide cycle power generation system and the organic Rankine cycle power generation system in sequence, and then enters the carbon dioxide in-situ utilization system; The carbon dioxide in-situ utilization system includes a condenser, a porous solid electrolytic cell and a formic acid storage tank. The exhaust gas entering the carbon dioxide in-situ utilization system is condensed by the condenser to separate H2O and then enters the cathode of the porous solid electrolytic cell. The cathode of the porous solid electrolytic cell includes a KOH solution and an anion exchange membrane, the anode of the porous solid electrolytic cell includes water and a cation exchange membrane, and the electrode catalyst of the porous solid electrolytic cell is bismuth oxide. The anode exhaust gas of the porous solid electrolytic cell enters the SOFC / GT system, and the formic acid discharged from the middle partition of the porous solid electrolytic cell enters the formic acid storage tank.

2. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1 is characterized in that: The SOFC / GT system includes a reforming chamber and a first heat exchanger. Water and methanol enter the reforming chamber after passing through the first heat exchanger. After heating the circulating working fluid of the supercritical carbon dioxide cycle power generation system, the exhaust gas first passes through the first heat exchanger to heat the water and methanol, and then heats the circulating working fluid of the organic Rankine cycle power generation system.

3. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1 is characterized in that: The circulating working fluid of the supercritical carbon dioxide cycle power generation system is heated by a heat exchanger before being cooled and compressed, and before being expanded and used for work in the organic Rankine cycle power generation system.

4. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1 or 3, characterized in that: The organic Rankine cycle power generation system includes a third turbine, a fourth heat exchanger, a fourth turbine, a third cooler and a working fluid pump connected in sequence. The circulating working fluid pumped by the working fluid pump is heated by the circulating working fluid of the supercritical carbon dioxide cycle power generation system and then enters the third turbine to perform work. The circulating working fluid discharged from the third turbine is heated by the exhaust gas in the fourth heat exchanger and then enters the fourth turbine to perform work.

5. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1 is characterized in that: The supercritical carbon dioxide circulation power generation system includes a first-stage supercritical carbon dioxide circulation power generation system and a second-stage supercritical carbon dioxide circulation power generation system. The exhaust gas of the gas turbine in the SOFC / GT system sequentially heats the circulating working fluid of the first-stage supercritical carbon dioxide circulation power generation system and the second-stage supercritical carbon dioxide circulation power generation system. The circulating working fluid in the organic Rankine cycle power generation system before expansion and work is heated sequentially by the circulating working fluid of the first-stage supercritical carbon dioxide circulation power generation system and the circulating working fluid of the second-stage supercritical carbon dioxide circulation power generation system.

6. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 5 is characterized in that: The first-stage supercritical carbon dioxide cycle power generation system includes a sixth heat exchanger, a first cooler, a first CO2 compressor, a fifth heat exchanger, a second heat exchanger and a first turbine. The circulating working fluid discharged from the first turbine preheats the circulating working fluid compressed by the first CO2 compressor in the fifth heat exchanger, enters the sixth heat exchanger to preheat the organic working fluid in the organic Rankine cycle power generation system, and then enters the first cooler. The circulating working fluid preheated in the fifth heat exchanger is heated by the exhaust gas in the second heat exchanger and then enters the first turbine.

7. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 5 is characterized in that: The second-stage supercritical carbon dioxide cycle power generation system includes an eighth heat exchanger, a second cooler, a second CO2 compressor, a seventh heat exchanger, a third heat exchanger and a second turbine. The circulating working fluid discharged from the second turbine preheats the circulating working fluid compressed by the second CO2 compressor in the seventh heat exchanger, enters the eighth heat exchanger to preheat the organic working fluid in the organic Rankine cycle power generation system, and then enters the second cooler. The circulating working fluid preheated in the seventh heat exchanger enters the second turbine after being heated by the exhaust gas in the third heat exchanger.

8. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1 is characterized in that: The anode of the porous solid electrolytic cell is connected to a second water pump, a fourth cooler and a water storage tank in sequence. The second water pump pumps the drainage water of the anode of the porous solid electrolytic cell into the fourth cooler, and the water in the water storage tank is provided to the anode of the porous solid electrolytic cell.

9. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1, characterized in that: The N2 discharged from the cathode of the porous solid electrolytic cell is connected to the middle partition layer to flush the porous solid and discharge formic acid.

10. The methanol fuel ship hybrid power system coupled with in-situ carbon dioxide capture and utilization according to claim 1, characterized in that: The electricity required for the operation of the carbon dioxide in-situ utilization system comes from the SOFC / GT system.

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