Marine methanol and dimethyl ether dual-fuel power system for preparing dimethyl ether on line

Abstract

The invention aims to provide an online dimethyl ether preparation type marine methanol dimethyl ether dual-fuel power system, and belongs to the field of power systems. Comprising a methanol-dimethyl ether hybrid internal combustion engine, a fuel tank, a dimethyl ether synthesis reactor, a dimethyl ether storage tank, a hydrogen storage tank and a carbon dioxide storage tank, the fuel tank is connected with a high-pressure common rail pipe through a methanol booster pump, and the high-pressure common rail pipe is connected with a methanol ejector of the methanol-dimethyl ether hybrid internal combustion engine; an air inlet manifold of the methanol and dimethyl ether mixed type internal combustion engine is connected with the air inlet channel. According to the invention, local carbon circulation of the marine methanol power system is realized, so that the carbon emission of the power system is greatly reduced. In addition, combustion of the mixed dimethyl ether can solve the problems of poor cold start performance and unstable low-load operation of single methanol, and stable and efficient operation of the methanol-dimethyl ether mixed internal combustion engine is realized.

Description

Technical Field

[0001] The present invention relates to a power system, specifically a low-carbon power system. Background Technology

[0002] Methanol, as a clean and renewable fuel, offers numerous advantages for internal combustion engine power systems. However, its application also presents several challenges. For example, methanol combustion alone results in poor cold-start performance and instability under low-load conditions. Furthermore, the high hydrocarbon and carbon oxide content in the exhaust gas from methanol-diesel mixtures limits its use in internal combustion engines. Using dimethyl ether (DME) instead of diesel in methanol-diesel blends can solve these problems. Moreover, producing DME from exhaust gas on-site and then mixing it with methanol in the internal combustion engine can achieve partial carbon recycling, significantly reducing carbon emissions from the power system. Summary of the Invention

[0003] The purpose of this invention is to provide an online dimethyl ether-based marine methanol-dimethyl ether dual-fuel power system that can solve the problems of poor cold start performance, unstable low-load operation, and large emissions of hydrocarbons and carbon oxides from methanol-diesel mixed combustion in the prior art.

[0004] The objective of this invention is achieved as follows:

[0005] This invention discloses an online dimethyl ether (DME)-based marine methanol-DME dual-fuel power system, characterized by comprising a methanol-DME hybrid internal combustion engine, a fuel tank, a DME synthesis reactor, a DME storage tank, a hydrogen storage tank, and a carbon dioxide storage tank. The fuel tank is connected to a high-pressure common rail via a methanol booster pump. The high-pressure common rail is connected to the methanol injector of the methanol-DME hybrid internal combustion engine. The intake manifold of the methanol-DME hybrid internal combustion engine is connected to the intake duct. The DME synthesis reactor includes a DME port, a carbon dioxide port, and a hydrogen port. The DME port is connected to a DME outlet. The DME outlet is connected to the DME inlet and the DME storage tank via a DME control valve. The DME inlet is connected to the intake duct. The carbon dioxide port is connected to the carbon dioxide storage tank via a carbon dioxide control valve. The hydrogen port is connected to the hydrogen storage tank via a hydrogen control valve. A DME purification device and a DME circulation pump are installed on the DME outlet. A methanol control valve is installed between the methanol booster pump and the high-pressure common rail.

[0006] The present invention may also include:

[0007] 1. It also includes a carbon dioxide capture and exhaust gas treatment device, which includes a carbon dioxide absorber, an absorbent circulation pump, a carbon dioxide separator, and a carbon dioxide circulation pump. The inlet of the carbon dioxide absorber is connected to the exhaust system of a methanol-dimethyl ether mixed internal combustion engine, and the outlet of the carbon dioxide absorber is connected to the carbon dioxide separator. The absorbent outlet of the carbon dioxide separator is connected to the carbon dioxide absorber through the absorbent circulation pump. An exhaust gas treatment device is installed on the top of the carbon dioxide absorber, and the gas outlet of the carbon dioxide separator is connected to a carbon dioxide control valve through the carbon dioxide circulation pump.

[0008] 2. It also includes a water electrolysis hydrogen production device, which includes a hydrogen circulation pump, a hydrogen drying device, a battery, a dehydration device, an electrolyzer, a deoxygenation device, a raw water control valve, a raw water circulation pump, a deionization device, a rectifier, and a generator. The raw water control valve is connected to the raw water circulation pump and the deoxygenation device. Seawater is fed to the raw water control valve through the seawater inlet. The deionization device is connected to the raw water circulation pump and the electrolyzer. The electrolyzer is equipped with a hydrogen outlet and an oxygen outlet. The hydrogen outlet is connected to the hydrogen control valve. A dehydration device, a hydrogen drying device, and a hydrogen circulation pump are respectively installed between the hydrogen outlet and the hydrogen control valve. The oxygen outlet is connected to the deoxygenation device.

[0009] 3. It also includes a generator, a rectifier, and a storage battery. The generator is connected to the transmission device of the methanol-dimethyl ether hybrid internal combustion engine. The rectifier is connected to both the generator and the storage battery. The storage battery is connected to the electrolytic cell.

[0010] 4. It also includes a heat pipe heat exchanger, a first tubular heat exchanger, and a second tubular heat exchanger. The heat pipe heat exchanger is installed between the dimethyl ether synthesis reactor and the air inlet; the first tubular heat exchanger is installed between the carbon dioxide absorber and the carbon dioxide separation device; and the second tubular heat exchanger is installed between the exhaust system of the methanol-dimethyl ether hybrid internal combustion engine and the carbon dioxide absorber.

[0011] The advantages of this invention are as follows: Under conditions of storing only liquid methanol fuel, this invention produces hydrogen through on-site electrolysis of seawater and extracts carbon dioxide from tail gas. The hydrogen and carbon dioxide are then dried and purified before being fed into a dimethyl ether synthesis reactor. Dimethyl ether is synthesized from the hydrogen and carbon dioxide under the action of a dual-action catalyst. The online-synthesized dimethyl ether is dehydrated and purified before being transported to the air intake duct to mix with air. The air-dimethyl ether mixture, along with methanol, enters the combustion chamber. Upon compression ignition, the dimethyl ether forms a high-temperature, rapidly propagating flame. This flame has extremely high energy, enabling rapid ignition of the methanol in the combustion chamber and reducing the methanol combustion delay period, thereby achieving stable ignition and rapid combustion of methanol.

[0012] This invention includes an electrolytic water hydrogen production device, a carbon dioxide capture and exhaust gas treatment device, and a dimethyl ether generation device. It can produce hydrogen, absorb carbon dioxide from exhaust gas, and synthesize dimethyl ether on-site. The synthesized dimethyl ether is transported to an internal combustion engine and mixed with methanol for combustion. Therefore, carbon cycling is achieved in a local area, which greatly reduces carbon emissions and improves combustion performance, solving the problems of poor cold start performance and high hydrocarbon emissions of methanol alone. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention.

[0014] Figure label:

[0015] 1: Fuel tank; 2: Methanol booster pump; 3: Methanol-dimethyl ether hybrid internal combustion engine

[0016] 4: Methanol control valve; 5: High-pressure common rail; 6: Methanol injector

[0017] 7: Heat pipe heat exchanger; 8: Air inlet; 9: Dimethyl ether synthesis reactor

[0018] 10: Dimethyl ether purification unit; 11: Dimethyl ether circulation pump; 12: Dimethyl ether control valve

[0019] 13: Dimethyl ether storage tank; 14: Hydrogen storage tank; 15: Carbon dioxide storage tank

[0020] 16: Carbon dioxide control valve; 17: Carbon dioxide circulation pump; 18: Carbon dioxide separator.

[0021] 19: Absorbent circulation pump; 20: Tubular heat exchanger 1; 21: Carbon dioxide absorber

[0022] 22: Hydrogen control valve; 23: Hydrogen circulation pump; 24: Hydrogen drying device

[0023] 25: Tubular heat exchanger 26: Storage battery 27: Dehydration device

[0024] 28: Hydrogen outlet; 29: Electrolyzer; 30: Oxygen outlet

[0025] 31: Deoxygenation unit; 32: Raw water control valve; 33: Raw water circulation pump

[0026] 34: Deionizer 35: Rectifier 36: Generator Detailed Implementation

[0027] The invention will now be described in more detail with reference to the accompanying drawings:

[0028] Combination Figure 1The present invention includes a fuel tank 1, a methanol booster pump 2, a methanol-dimethyl ether hybrid internal combustion engine 3, a methanol control valve 4, a high-pressure common rail 5, a methanol injector 6, an intake manifold 8, an exhaust system, and a transmission device.

[0029] Fuel tank 1 is used to store liquid methanol. Fuel tank 1 is equipped with a methanol discharge port, which is connected to methanol booster pump 2 to supply low-pressure methanol to the booster pump for pressurization.

[0030] The methanol booster pump 2 is used to compress and pressurize low-pressure liquid methanol into high-pressure methanol. The inlet of the methanol booster pump 2 is connected to the fuel tank 1 and is equipped with a regulating valve to control the flow rate of low-pressure liquid methanol. The outlet of the methanol booster pump 2 is connected to the high-pressure common rail pipe 5 through the methanol control valve 4.

[0031] The methanol-dimethyl ether hybrid internal combustion engine 3 includes a methanol injector 6, an intake manifold 8, a combustion chamber, an exhaust system, and a transmission device.

[0032] The combustion chamber is connected to the intake duct 8, and a heat pipe heat exchanger 7 is arranged between the combustion chamber and the intake duct 8. A dimethyl ether injection device is installed in the intake duct 8, injecting dimethyl ether from the dimethyl ether synthesis unit into the intake duct 8 via the dimethyl ether control valve 12 to mix with air. The heat pipe heat exchanger 7 uses the heat released from the dimethyl ether synthesis reaction in the dimethyl ether synthesizer 9 to heat the air and dimethyl ether mixture in the intake duct 8. Furthermore, the intake duct 8 delivers the preheated air and dimethyl ether mixture to the combustion chamber. A methanol injector 6 is installed on the methanol-dimethyl ether mixture internal combustion engine 3. One end of the methanol injector 6 is connected to the high-pressure common rail 5, and the other end is connected to the combustion chamber. It is used to inject high-pressure methanol into the combustion chamber and control the injection pattern of high-pressure methanol. The exhaust system discharges the exhaust gas after combustion in the methanol-dimethyl ether mixture internal combustion engine 3, and the transmission device outputs the work done by the methanol-dimethyl ether mixture internal combustion engine.

[0033] The methanol-dimethyl ether hybrid internal combustion engine also includes pistons, crankshaft connecting rods, cylinder blocks, etc., which are existing technologies and are not the focus of this article, so they will not be discussed further.

[0034] The carbon dioxide capture and exhaust gas treatment device includes a carbon dioxide absorber 21, an absorbent circulation pump 19, a carbon dioxide separation device 18, a carbon dioxide circulation pump 17, a carbon dioxide control valve 16, a carbon dioxide storage tank 15, and an exhaust gas treatment device.

[0035] The inlet of the carbon dioxide absorber 21 is connected to the exhaust system of the methanol-dimethyl ether mixed internal combustion engine 3. Exhaust gas is transported from the exhaust system to the carbon dioxide absorber 21 via a pipeline, passing through a shell-and-tube heat exchanger 24, where it is cooled. The cooled exhaust gas is captured by the absorbent liquid in the carbon dioxide absorber 21, and the carbon dioxide-rich absorbent liquid enters the carbon dioxide separator 18, where carbon dioxide and absorbent liquid are separated. The separated absorbent liquid is returned to the carbon dioxide absorber 21 by an absorbent liquid circulation pump. An exhaust gas treatment device is installed at the top of the carbon dioxide absorber 21, which absorbs and treats the remaining exhaust gas using catalytic reduction technology. The carbon dioxide separated in the carbon dioxide separator 18 is further dried and purified. The dried carbon dioxide is then pumped by the carbon dioxide circulation pump 17 through the carbon dioxide control valve 16 to the carbon dioxide storage tank 15 and the carbon dioxide inlet of the dimethyl ether synthesizer 9, respectively. The carbon dioxide control valve 16 is connected to the control module, which can adjust the flow rate of carbon dioxide and regulate the connection between the carbon dioxide circulation pump 17, the carbon dioxide storage tank 15, and the dimethyl ether synthesizer 9 based on the operating status of the methanol-dimethyl ether hybrid internal combustion engine 3.

[0036] The dimethyl ether synthesis apparatus includes a dimethyl ether synthesis reactor 9, a dimethyl ether purification unit 10, a dimethyl ether circulation pump 11, a dimethyl ether control valve 12, and a dimethyl ether storage tank 13.

[0037] The dimethyl ether synthesis reactor 9 also includes a hydrogen inlet and a carbon dioxide inlet. The hydrogen inlet is connected to a hydrogen control valve 22 to supply hydrogen generated in the water electrolysis hydrogen production unit to the dimethyl ether synthesizer 9. The carbon dioxide inlet is connected to a carbon dioxide control valve 16 to supply carbon dioxide to the dimethyl ether synthesizer 9 for synthesis of dimethyl ether with hydrogen under the action of a dual catalyst. The outlet of the dimethyl ether synthesis reactor is connected to a dimethyl ether purification unit 10, where the synthesized dimethyl ether is dried and purified. Further, the purified dimethyl ether is pumped by the dimethyl ether circulation pump 11 through the dimethyl ether control valve 12 to the inlet duct 8 or the dimethyl ether storage tank 13.

[0038] The dimethyl ether control valve 12 is electrically connected to the control module and can adjust the flow rate and direction of dimethyl ether based on the operating status of the methanol-dimethyl ether hybrid internal combustion engine 3. When the amount of dimethyl ether required by the methanol-dimethyl ether hybrid internal combustion engine 3 is less than the amount generated by the dimethyl ether synthesizer 9, the excess dimethyl ether generated is transported to the dimethyl ether storage tank under the action of the dimethyl ether control valve 12. When the amount of dimethyl ether required by the methanol-dimethyl ether hybrid internal combustion engine 3 is greater than the amount generated by the dimethyl ether synthesizer 9, the dimethyl ether in the dimethyl ether storage tank is transported to the intake manifold 8 under the regulation of the dimethyl ether control valve 12.

[0039] The water electrolysis hydrogen production unit includes a hydrogen storage tank 14, a hydrogen control valve 22, a hydrogen circulation pump 23, a hydrogen drying device 24, a storage battery 26, a dehydration device 27, an electrolyzer 29, a deoxygenation device 31, a raw water control valve 32, a raw water circulation pump 33, a deionization device 34, a rectifier 35, a generator 36, and a seawater inlet.

[0040] Seawater enters the water electrolysis hydrogen production system through the seawater inlet. The raw water control valve 32 is connected to the raw water circulation pump 33 and the deoxygenation device 31 to control the flow rate of raw water entering the electrolyzer for electrolysis. The deionization device 34 is connected to the outlet of the raw water circulation pump 33 to filter and purify the pumped raw water. The electrolyzer 29 is connected to the outlet of the deionization device 34, where the filtered and purified water is electrolyzed to produce hydrogen. The hydrogen produced by electrolysis is transported from the hydrogen outlet 28 to the dehydration device 27. The inlet of the hydrogen drying device 24 is connected to the outlet of the dehydration device 27. The connecting pipeline passes through the tubular heat exchanger 25, where the hydrogen is heated and further dried and purified in the hydrogen drying device 24. The extracted hydrogen, under the action of the hydrogen circulation pump, is transported through the hydrogen control valve 22 to the dimethyl ether synthesis reactor 9 and the hydrogen storage tank 14.

[0041] The hydrogen control valve 22 is electrically connected to the control module and can regulate the flow rate of hydrogen based on the operating status of the methanol-dimethyl ether hybrid internal combustion engine 3. It can also regulate the connection between the dimethyl ether synthesis reactor 9, the hydrogen storage tank 14, and the hydrogen circulation pump 23.

[0042] The hydrogen control valve 22 can regulate the flow direction of hydrogen. For example, when the demand for dimethyl ether in the methanol-dimethyl ether hybrid internal combustion engine 3 decreases, the hydrogen control valve 22 can reduce the hydrogen flow rate to the dimethyl ether synthesis reactor 9 under the action of the control module, while increasing the hydrogen flow rate to the hydrogen storage tank 14, thereby achieving precise control of the hydrogen flow rate and avoiding the waste of excess hydrogen.

[0043] The presence of the high-pressure common rail 5 ensures that the operation of the methanol booster pump 2 does not affect the injection pressure of the methanol injector 6. The high-pressure common rail 5 can store a certain amount of high-pressure fuel, maintain stable fuel pressure and flow, and effectively eliminate pressure fluctuations in the fuel, ensuring that the injection pressure remains instantaneously stable when the injector is activated. Based on this characteristic, the methanol booster pump 2 can maintain a consistently high-efficiency operating state to provide high-pressure liquid methanol to the methanol-dimethyl ether hybrid internal combustion engine 9, further improving combustion performance.

[0044] The methanol injector 6 is an electronically controlled injector. Electrically connected to the control module, it controls the opening and closing of the solenoid valve to inject methanol fuel from the high-pressure fuel rail into the combustion chamber of the internal combustion engine at optimal injection timing, quantity, and rate. The methanol injector achieves an ideal injection pattern, easily enabling pre-injection and multiple injections, which helps reduce emissions from the methanol-dimethyl ether hybrid internal combustion engine 3 while ensuring excellent power and fuel economy. Furthermore, the injection pressure in the high-pressure common rail system is flexibly adjustable, allowing for the determination of the optimal injection pressure for different operating conditions, thereby optimizing the overall performance of the powertrain.

[0045] In the embodiments provided by the present invention, a generator 36, a rectifier 35, and a battery 26 are also provided for providing electrical energy to the water electrolysis hydrogen production device.

[0046] The generator 36 is connected to the transmission device, converting part of the power output of the methanol-dimethyl ether hybrid internal combustion engine into electrical energy. A rectifier 35 is installed between the generator 36 and the battery 26 to adjust and convert the current generated by the generator for use by the battery. The battery 26 provides electrical energy for the electrolytic reaction in the electrolyzer.

[0047] In the embodiments provided by the present invention, a waste heat recovery module is also provided, which consists of a heat pipe heat exchanger 7, a shell-and-tube heat exchanger 25, and a shell-and-tube heat exchanger 20.

[0048] A heat pipe heat exchanger is installed between the intake duct 8 and the dimethyl ether synthesis reactor 9. It absorbs the heat released from the dimethyl ether synthesis reaction in the reactor 9, lowering the internal temperature and directing the synthesis reaction in the forward direction to increase the dimethyl ether synthesis rate. Simultaneously, the absorbed heat is used to preheat the air-dimethyl ether mixture in the intake duct 8. This preheated mixture improves engine starting performance, thus improving combustion conditions during cold starts. Furthermore, it improves the temperature distribution within the combustion chamber, increasing combustion efficiency and contributing to improved power output and fuel economy of the methanol-dimethyl ether hybrid internal combustion engine 3.

[0049] The shell-and-tube heat exchanger 25 is installed between the hydrogen drying pipeline and the tail gas discharge pipeline to absorb heat from the tail gas to heat the hydrogen and water mixture at the hydrogen outlet of the electrolyzer, making the hydrogen easier to further dry and purify.

[0050] The shell-and-tube heat exchanger 20 is installed between the carbon dioxide absorber 21 and the carbon dioxide separation device 19 to maintain the temperature of the carbon dioxide absorbent liquid so that the capture and separation of carbon dioxide are more complete.

Claims

1. An online dimethyl ether-based marine methanol-dimethyl ether dual-fuel power system, characterized in that: The system includes a methanol-dimethyl ether (DME) hybrid internal combustion engine, a fuel tank, a dimethyl ether synthesis reactor, a dimethyl ether storage tank, a hydrogen storage tank, and a carbon dioxide storage tank. The fuel tank is connected to a high-pressure common rail via a methanol booster pump. The high-pressure common rail is connected to the methanol injector of the methanol-dimethyl ether hybrid internal combustion engine. The intake manifold of the methanol-dimethyl ether hybrid internal combustion engine is connected to the intake duct. The dimethyl ether synthesis reactor includes a dimethyl ether port, a carbon dioxide port, and a hydrogen port. The dimethyl ether port is connected to a dimethyl ether outlet. The dimethyl ether outlet is connected to the dimethyl ether inlet and the dimethyl ether storage tank via a dimethyl ether control valve. The dimethyl ether inlet is connected to the intake duct. The carbon dioxide port is connected to the carbon dioxide storage tank via a carbon dioxide control valve. The hydrogen port is connected to the hydrogen storage tank via a hydrogen control valve. A dimethyl ether purification device and a dimethyl ether circulation pump are installed on the dimethyl ether outlet. A methanol control valve is installed between the methanol booster pump and the high-pressure common rail.

2. The online dimethyl ether-based marine methanol-dimethyl ether dual-fuel power system according to claim 1, characterized in that: It also includes a carbon dioxide capture and exhaust gas treatment device, which includes a carbon dioxide absorber, an absorbent circulation pump, a carbon dioxide separator, and a carbon dioxide circulation pump. The inlet of the carbon dioxide absorber is connected to the exhaust system of a methanol-dimethyl ether mixed internal combustion engine, and the outlet of the carbon dioxide absorber is connected to the carbon dioxide separator. The absorbent outlet of the carbon dioxide separator is connected to the carbon dioxide absorber through the absorbent circulation pump. An exhaust gas treatment device is installed on the top of the carbon dioxide absorber, and the gas outlet of the carbon dioxide separator is connected to a carbon dioxide control valve through the carbon dioxide circulation pump.

3. The online dimethyl ether-based marine methanol-dimethyl ether dual-fuel power system according to claim 1, characterized in that: It also includes a water electrolysis hydrogen production device, which comprises a hydrogen circulation pump, a hydrogen drying device, a battery, a dehydration device, an electrolyzer, a deoxygenation device, a raw water control valve, a raw water circulation pump, a deionization device, a rectifier, and a generator. The raw water control valve is connected to the raw water circulation pump and the deoxygenation device. Seawater is fed to the raw water control valve through a seawater inlet. The deionization device is connected to the raw water circulation pump and the electrolyzer. The electrolyzer has a hydrogen outlet and an oxygen outlet. The hydrogen outlet is connected to the hydrogen control valve. A dehydration device, a hydrogen drying device, and a hydrogen circulation pump are respectively installed between the hydrogen outlet and the hydrogen control valve. The oxygen outlet is connected to the deoxygenation device.

4. The online dimethyl ether-based marine methanol-dimethyl ether dual-fuel power system according to claim 3, characterized in that: It also includes a generator, a rectifier, and a battery. The generator is connected to the transmission of a methanol-dimethyl ether hybrid internal combustion engine. The rectifier is connected to both the generator and the battery. The battery is connected to an electrolytic cell.

5. The online dimethyl ether-based marine methanol-dimethyl ether dual-fuel power system according to claim 1, characterized in that: It also includes a heat pipe heat exchanger, a first tubular heat exchanger, and a second tubular heat exchanger. The heat pipe heat exchanger is installed between the dimethyl ether synthesis reactor and the air inlet; the first tubular heat exchanger is installed between the carbon dioxide absorber and the carbon dioxide separation device; and the second tubular heat exchanger is installed between the exhaust system of the methanol-dimethyl ether hybrid internal combustion engine and the carbon dioxide absorber.

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