Self-powered lng cold energy for hydrogen production and hydrogen liquefaction cogeneration device and working method

Abstract

The application discloses a self-powered LNG cold energy hydrogen production and hydrogen liquefaction cogeneration device and a working method, and specifically comprises an LNG gasification power generation system, a self-powered water electrolysis hydrogen production system, a nitrogen expansion precooling system and a hydrogen pressurization liquefaction system. The application utilizes LNG gasification cold energy and expansion work power in the hydrogen liquefaction system to generate electricity and provide power for the water electrolysis hydrogen production system, and purified hydrogen is cooled into liquid hydrogen by a low-temperature liquefaction system. The application is provided with a control system, which controls parallel flow path flow and compressor pressure ratio to ensure stable operation of the system. The application fully utilizes LNG gasification cold energy and frequently wasted expansion work power in the hydrogen liquefaction system to reduce the electricity cost in the water electrolysis hydrogen production process, avoids waste of LNG cold energy resources in a gas peaking station, and realizes the purpose of LNG cold energy power generation, hydrogen production and hydrogen liquefaction cogeneration under the condition of no external power supply.

Description

Technical Field

[0001] This invention relates to a cold energy utilization, hydrogen production and hydrogen liquefaction system, and more particularly to a self-powered LNG cold energy cogeneration device and operating method for hydrogen production and hydrogen liquefaction. Background Technology

[0002] my country's dual-carbon goals have accelerated the pace of energy transition, with clean energy sources such as natural gas and hydrogen receiving significant attention. LNG releases a large amount of cold energy during its vaporization process; if this cold energy can be fully utilized, resource waste will be greatly reduced.

[0003] Electrolysis of water to produce hydrogen has long been considered the most promising hydrogen production technology, but its power generation cost is too high. With the rapid development of renewable energy, the cost of wind and solar power generation is gradually decreasing. Utilizing renewable energy to power water electrolysis for hydrogen production is another trend for its future development. For example, patent CN201810994775.3 mentions using solar and wind power generation technologies to produce hydrogen, providing a raw material for natural gas. Patent CN202121990680.8 addresses the low efficiency problem of using solar and wind power for water electrolysis, promoting the development of renewable energy-powered water electrolysis for hydrogen production.

[0004] The density of liquid hydrogen at atmospheric pressure is 70.9 kg / m³. 3 This is equivalent to 1.8 times the density of hydrogen at 70 MPa. Therefore, cryogenic liquid hydrogen storage has significant advantages in terms of storage density and capacity. Under the vision of carbon peaking and carbon neutrality, developing the hydrogen energy industry is an important way to achieve a green and low-carbon energy transformation.

[0005] LNG cold energy resources at gas peak-shaving stations or receiving terminals are often wasted. Considering that power reserves are usually tight in areas with high electricity demand, and that hydrogen production by water electrolysis requires a large amount of electricity, and that the approval process for high-load electricity use is lengthy, it is urgent to find a stable and reliable way to achieve hydrogen production and hydrogen liquefaction co-production without external power supply. Summary of the Invention

[0006] Purpose of the Invention: To address the aforementioned problems, the purpose of this invention is to provide a self-powered LNG cold energy co-production device for hydrogen production and liquefaction. This device utilizes part of the cold energy from the LNG cold energy and hydrogen liquefaction system to generate electricity, providing power for hydrogen production via water electrolysis. This effectively reduces the cost of hydrogen production via water electrolysis, fully utilizes cold energy, and produces clean liquid hydrogen, solving the problems of high energy consumption in hydrogen production and hydrogen storage and transportation. The invention also provides its operating method.

[0007] Technical solution: A self-powered LNG cold energy-based hydrogen production and hydrogen liquefaction co-production unit, including an LNG gasification power generation system, a self-powered water electrolysis hydrogen production system, a nitrogen expansion precooling system, and a hydrogen pressurization liquefaction system;

[0008] The LNG storage tank outlet of the LNG gasification power generation system is connected to the inlet of submersible pump 1. The outlet of submersible pump 1 is connected to the inlet of flow meter 1. The outlet of flow meter 1 is divided into two paths: one path is connected to the hydrogen pressurization liquefaction system, and the other path is connected to the inlet of ball valve 1. The outlet of ball valve 1 is connected to the H1 inlet of LNG vaporizer H. The H3 outlet of LNG vaporizer H is connected to the inlet of working fluid pump. The outlet of working fluid pump is connected to the F1 inlet of the sixth heat exchanger F. The F3 outlet of the sixth heat exchanger F is connected to the inlet of turbine expander 3. Turbine expander 3 is connected to generator 1. The outlet of turbine expander 3 is connected to the H2 inlet of LNG vaporizer H. The H4 outlet of LNG vaporizer H is connected to the E3 inlet of the fifth heat exchanger E. The E2 outlet of the fifth heat exchanger E is connected to the inlet of back pressure valve 1.

[0009] The inverter of the self-generated water electrolysis hydrogen production system is connected to the X1 inlet of the electrolyzer. The raw water is connected to the inlet of ball valve three. The outlet of ball valve three is connected to the X2 inlet of the electrolyzer. The X4 outlet of the electrolyzer is connected to the inlet of shut-off valve one. The outlet of shut-off valve one is connected to the inlet of the oxygen storage tank. The X3 outlet of the electrolyzer is connected to the inlet of the deoxygenation drying device. The outlet of the deoxygenation drying device is connected to the inlet of flow meter two. The outlet of flow meter two is connected to shut-off valve two. Shut-off valve two is connected to the hydrogen pressurization liquefaction system.

[0010] The outlet of the nitrogen compressor in the nitrogen expansion precooling system is connected to the inlet of the second check valve. The outlet of the second check valve is connected to the inlet of the third cooler. The outlet of the third cooler is connected to the hydrogen boosting and liquefaction system, and then back to the Y1 inlet of the turbine booster. The Y2 outlet of the turbine booster is then back to the Y4 inlet of the booster of the turbine booster via the hydrogen boosting and liquefaction system. The Y3 outlet of the booster of the turbine booster is connected to the inlet of the nitrogen compressor.

[0011] The hydrogen in the hydrogen pressurization and liquefaction system is processed sequentially through the LNG precooling section, the nitrogen expansion precooling section, and the turbine expander cooling section, and then enters the liquid hydrogen storage tank for storage after passing through the throttle valve.

[0012] The LNG precooling section provides LNG through the LNG gasification power generation system. Flow meter one is connected to the hydrogen pressurization liquefaction system through ball valve two. The outlet of ball valve two is connected to the B10 inlet of the second heat exchanger B. The B9 outlet of the second heat exchanger B is connected to the A10 inlet of the first heat exchanger A. The A9 outlet of the first heat exchanger A is connected to the inlet of back pressure valve two. The outlet of back pressure valve two merges with the outlet of back pressure valve one and is then regulated before being connected to the user unit. The outlet of hydrogen compressor two in the LNG precooling section is connected to the inlet of check valve one. The outlet of check valve one is connected to the inlet of cooler two. The outlet of cooler two is connected to the A4 inlet of the first heat exchanger A. The A3 outlet of the first heat exchanger A is connected to the B4 inlet of the second heat exchanger B. The B3 outlet of the second heat exchanger B is connected to the C4 inlet of the third heat exchanger C.

[0013] The nitrogen expansion precooling section provides N2 through the nitrogen expansion precooling system. The C4 inlet of the third heat exchanger C in the nitrogen expansion precooling section is connected to the B3 outlet of the second heat exchanger B.

[0014] The inlet of the fourth heat exchanger D in the cooling section of the turbine expander is connected to the outlet of the third heat exchanger C, which is connected to the inlet of the throttle valve. The outlet of the throttle valve is connected to the inlet of the liquid hydrogen storage tank. The fourth shut-off valve is connected to the outlet of the third heat exchanger C, which is connected to the inlet of the second turbine expander. The second turbine expander is connected to the third generator. The outlet of the second turbine expander merges with the outlet of the liquid hydrogen storage tank and is then connected to the inlet of the fourth heat exchanger D, which is connected to the inlet of the fourth heat exchanger D. The outlet of the fourth heat exchanger D is connected to the inlet of the third heat exchanger C, which is connected to the inlet of the third heat exchanger C, which is connected to the inlet of the third heat exchanger C.

[0015] Furthermore, the A3 outlet of the first heat exchanger A is also connected to the inlet of the third shut-off valve, the outlet of the third shut-off valve is connected to the inlet of the first turbine expander, the first turbine expander is connected to the second generator, the outlet of the first turbine expander is connected to the C1 outlet of the third heat exchanger C and then connected to the B2 inlet of the second heat exchanger B, the B1 outlet of the second heat exchanger B is connected to the A2 inlet of the first heat exchanger A, and the electrical energy generated by the second generator, the first generator, and the third generator is combined and then enters the electrolytic cell for reciprocating circulation through the inverter.

[0016] Furthermore, after the B1 outlet end of the second heat exchanger B is connected to the A2 inlet end of the first heat exchanger A, it is then connected to the inlet end of the hydrogen compressor one via the A1 outlet end of the first heat exchanger A. The outlet end of the hydrogen compressor one is connected to the inlet end of the cooler one. The outlet end of the cooler one merges with the outlet end of the shut-off valve two and is then connected to the hydrogen compressor two.

[0017] Ideally, the device also includes a control unit. The control unit is connected between the A1 outlet end of the first heat exchanger A and the inlet end of the hydrogen compressor one. The hydrogen compressor two, nitrogen compressor one, ball valve two, throttle valve, ball valve four, shut-off valve four, and shut-off valve three are respectively connected to the control unit via signal.

[0018] The control unit receives the pressure, temperature, and flow values ​​of the system's measurement section. By adjusting the opening degrees of shut-off valve three, shut-off valve four, throttle valve, ball valve two, and ball valve four, as well as the speeds of hydrogen compressor one, hydrogen compressor two, and nitrogen compressor one, the system operates normally within the set parameter range.

[0019] The control unit collects data from measurement points and then adjusts the equipment and actuators in each module to ensure the safe and stable operation of the system. The parameters set by the temperature and pressure measurement points distributed in each system and the control unit are as follows: hydrogen pressure a(P1), e(P2), f(P3), g(P4); hydrogen temperature b(T1), c(T2), h(T3), i(T4). The specific adjustment methods are as follows:

[0020] By adjusting the speeds of hydrogen compressor 2, hydrogen compressor 1, and nitrogen compressor 1, the pressures at points a, f, and g are controlled to reach the set values ​​P1, P3, and P4, respectively. By detecting the pressure values ​​at points d and e, hydrogen compressor 1 is controlled to make the pressure values ​​at points d and e equal. By adjusting the openings of ball valve 2, throttle valve, ball valve 4, shut-off valve 4, and shut-off valve 3, the temperatures at points b, c, h, and i are controlled to reach the set values ​​T1, T2, T3, and T4, respectively.

[0021] Furthermore, the nitrogen expansion precooling system also includes a nitrogen replenishment tank. The outlet end of the nitrogen replenishment tank is connected to the inlet end of ball valve four. The outlet end of ball valve four merges with the Y3 outlet end of the turbocharger and is then connected to the inlet end of nitrogen compressor one.

[0022] The outlet end of cooler three is connected to the inlet end A7 of the first heat exchanger A. The outlet end A8 of the first heat exchanger A is connected to the inlet end B7 of the second heat exchanger B. The outlet end B8 of the second heat exchanger B is connected to the inlet end Y1 of the expansion end of the turbocharger. The outlet end Y2 of the expansion end of the turbocharger is connected to the inlet end C6 of the third heat exchanger C. The outlet end C5 of the third heat exchanger C is connected to the inlet end B6 of the second heat exchanger B. The outlet end B5 of the second heat exchanger B is connected to the inlet end A6 of the first heat exchanger A. The outlet end A5 of the first heat exchanger A is connected to the inlet end Y4 of the turbocharger.

[0023] Furthermore, the first heat exchanger A, the second heat exchanger B, the third heat exchanger C, and the fourth heat exchanger D are all microchannel plate-fin heat exchangers. Among them, the microchannels of the second heat exchanger B, the third heat exchanger C, and the fourth heat exchanger D are filled with positive and negative hydrogen conversion catalyst particles.

[0024] Ideally, the electrolyzer produces hydrogen by electrolyzing water through alkaline hydrolysis, proton exchange membrane hydrolysis, and high-temperature solid oxide hydrolysis; the deoxygenation drying unit uses a method of reacting with oxygen to generate water, and obtains the desired gas through deoxygenation purification.

[0025] Ideally, the working fluid in an LNG cold power generation system is propane, trifluoromethane, ethylene, or a mixture of these working fluids.

[0026] Ideally, coolers 1, 2, and 3 should be water-cooled, and flow meters 1 and 2 should be Venturi flow meters.

[0027] A method for operating a hydrogen production and liquefaction cogeneration unit using the aforementioned self-powered LNG cold energy includes the following steps:

[0028] Step 1: Start the device. LNG in the LNG storage tank enters Flow Meter 1 via Submersible Pump 1. The outlet of Flow Meter 1 splits into two paths. The first path enters LNG Vaporizer H via Ball Valve 1 to release cold energy and exchange heat with the working fluid in the power generation cycle system. After being pressurized by the working fluid pump, the working fluid enters the sixth heat exchanger F to exchange heat with cooling water. The working fluid temperature rises and enters Turbine Expander 3 to drive Generator 1 and generate electricity. The second outlet of Flow Meter 1 enters the second heat exchanger B via Ball Valve 2 for heat exchange, and the temperature rises. Then it enters the first heat exchanger A, where the temperature rises further. The pressure is stabilized by Back Pressure Valve 2. After passing through LNG Vaporizer H, LNG becomes NG, and the temperature rises further. It enters the fifth heat exchanger E to exchange heat with cooling water. The NG temperature rises further and enters Back Pressure Valve 1 to stabilize the pressure. The outlets of Back Pressure Valve 2 and Back Pressure Valve 1 merge and, after regulation, enter the user end.

[0029] Step 2: The electrical energy generated by generator 1 enters the electrolyzer via the inverter. The oxygen generated by the electrolyzer enters the oxygen storage tank through shut-off valve 1. The hydrogen generated by the electrolyzer enters the deoxygenation drying unit for hydrogen purification. The raw water is replenished by ball valve 3 to supplement the raw water consumed in the hydrogen production process. The purified hydrogen enters shut-off valve 2 through flow meter 2, then enters hydrogen compressor 2 for pressurization, enters check valve 1, and enters LNG precooling section after being cooled by cooler 2. It then passes through heat exchanger A and heat exchanger B for cooling in sequence.

[0030] Step 3: Nitrogen enters the nitrogen expansion and pre-cooling section; nitrogen is pressurized from nitrogen compressor one, passes through check valve two and enters cooler three for cooling, then enters heat exchanger A and heat exchanger B for further cooling, and then enters turbine compressor for expansion; nitrogen from turbine compressor enters heat exchanger C, heat exchanger B and heat exchanger A in sequence for reheating, then enters turbine compressor for further pressurization and enters nitrogen compressor one for further pressurization, entering the next cycle;

[0031] Step 4: After the LNG precooling section ends, hydrogen enters the nitrogen expansion precooling section and is cooled by the third heat exchanger C;

[0032] Step 5: After the nitrogen expansion precooling section ends, the hydrogen enters the turbine expander cooling section. The hydrogen gas cooled in the third heat exchanger C is divided into two paths. The first path is cooled by the fourth heat exchanger D and then enters the throttle valve for further cooling before entering the liquid hydrogen storage tank. The second path enters the turbine expander II through the shut-off valve IV for cooling, which drives the generator III to run and generate electricity. Then, it merges with the low-temperature hydrogen gas from the liquid hydrogen storage tank and enters the fourth heat exchanger D and the third heat exchanger C in sequence for reheating.

[0033] After being cooled in the first heat exchanger A, the second path of hydrogen enters the first turbine expander through the third shut-off valve for further cooling, driving the second generator to run and generate electricity. The electricity is then transferred to the electrolytic cell, and then merges with the hydrogen that has been reheated in the third heat exchanger C. After being reheated, it enters the second heat exchanger B and the first heat exchanger A in sequence, and then enters the first hydrogen compressor for pressurization. After being cooled in the first cooler, it merges with the hydrogen that comes out from the second shut-off valve and enters the second hydrogen compressor (103) for pressurization, and then enters the next cycle.

[0034] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0035] 1. This invention utilizes an LNG cold energy power generation and hydrogen liquefaction system expansion power generation system to provide electricity for hydrogen production through water electrolysis without the need for external power supply, effectively reducing the cost of hydrogen production through water electrolysis. Furthermore, by coupling readily available LNG gasification cold energy with a hydrogen cryogenic liquefaction system, the industrial goal of producing and liquefying hydrogen with self-powered, low-energy consumption is achieved.

[0036] 2. The present invention arranges catalytic particles for the conversion of positive and negative hydrogen in the microchannels of the second, third and fourth heat exchangers, which saves the space occupied by the traditional positive-negative hydrogen conversion device, and greatly saves the initial investment and space occupation of the equipment.

[0037] 3. This invention avoids the waste of LNG cold energy resources in gas peak shaving stations, realizes energy transfer and consumption through hydrogen energy, and ultimately solves the industry pain point of hydrogen energy storage and transportation in the form of liquid hydrogen. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0039] Figure 2 For hydrogen in Figure 1 Pressure control diagram at point a;

[0040] Figure 3 For hydrogen in Figure 1 Temperature control graph at point b;

[0041] Figure 4 For hydrogen in Figure 1 Temperature control graph at point c;

[0042] Figure 5 For hydrogen in Figure 1 Pressure control diagram at point d;

[0043] Figure 6 For nitrogen gas in Figure 1 Pressure control diagram at point f;

[0044] Figure 7 For nitrogen gas in Figure 1 Pressure control diagram at point g;

[0045] Figure 8 For hydrogen in Figure 1 Temperature control graph at point h;

[0046] Figure 9 For hydrogen in Figure 1 Temperature control graph at point i. Detailed Implementation

[0047] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0048] A self-powered LNG cold energy cogeneration unit and operating method for hydrogen production and liquefaction, such as Figure 1 As shown, it includes an LNG gasification power generation system, a self-generated water electrolysis hydrogen production system, a nitrogen expansion precooling system, and a hydrogen pressurization liquefaction system.

[0049] The LNG vaporization power generation system consists of an LNG storage tank 301 outlet connected to a submersible pump 310 inlet. The outlet of submersible pump 310 is connected to a flow meter 302 inlet. The flow meter 302 outlet is split into two lines: the first line outlet is connected to a ball valve 306 inlet, the ball valve 306 outlet is connected to the LNG vaporizer H's H1 inlet, the LNG vaporizer H's H3 outlet is connected to a working fluid pump 307 inlet, and the working fluid pump 307 outlet is connected to the sixth heat exchanger F's F1 inlet. The sixth heat exchanger F is connected to the F3 outlet end of the turbine expander 308. Cooling water flows in from the F4 inlet end of the sixth heat exchanger F and flows out from the F2 outlet end. The turbine expander 308 is connected to the generator 309. The outlet end of the turbine expander 308 is connected to the H2 inlet end of the LNG vaporizer H. The H4 outlet end of the LNG vaporizer H is connected to the E3 inlet end of the fifth heat exchanger E. The E2 outlet end of the fifth heat exchanger E is connected to the inlet end of the back pressure valve 305.

[0050] The self-generated water electrolysis hydrogen production system consists of an inverter 201 connected to the X1 inlet of an electrolyzer 205, raw water connected to the inlet of ball valve 3 202, the outlet of ball valve 3 202 connected to the X2 inlet of an electrolyzer 205, the X4 outlet of an electrolyzer 205 connected to the inlet of a stop valve 1 204, the outlet of a stop valve 1 204 connected to the inlet of an oxygen storage tank 203, the X3 outlet of an electrolyzer 205 connected to the inlet of a deoxygenation drying device 206, the outlet of a deoxygenation drying device 206 connected to the inlet of a flow meter 207, and the outlet of a flow meter 207 connected to a stop valve 208.

[0051] The nitrogen expansion precooling system connects the outlet of nitrogen compressor 116 to the inlet of check valve 114, the outlet of check valve 114 to the inlet of cooler 115, the outlet of cooler 115 to the inlet of first heat exchanger A (A7), the outlet of first heat exchanger A (A8) to the inlet of second heat exchanger B (B7), the outlet of second heat exchanger B (B8) to the inlet of expansion end of turbocharger 112 (Y1), and the outlet of expansion end (Y2) to the inlet of third heat exchanger C (C6). The third heat exchanger C's C5 outlet is connected to the second heat exchanger B's B6 inlet. The second heat exchanger B's B5 outlet is connected to the first heat exchanger A's A6 inlet. The first heat exchanger A's A5 outlet is connected to the turbocharger 112's Y4 inlet. The nitrogen replenishment tank 117 outlet is connected to the ball valve 118 inlet. The ball valve 118 outlet and the turbocharger 112's Y3 outlet merge and are then connected to the nitrogen compressor 116 inlet.

[0052] In the hydrogen pressurization and liquefaction system, the hydrogen gas is pre-cooled by LNG, pre-cooled by nitrogen expansion, and cooled by a turbine expander in sequence, and finally further liquefied by a throttle valve.

[0053] The LNG precooling section is connected from the outlet of LNG storage tank 301 to the inlet of submersible pump 310. The outlet of submersible pump 310 is connected to the inlet of flow meter 302. The second outlet of flow meter 302 is connected to the inlet of ball valve 303. The outlet of ball valve 303 is connected to the inlet of heat exchanger B10. The outlet of heat exchanger B9 is connected to the inlet of heat exchanger A10. The outlet of heat exchanger A9 is connected to the inlet of back pressure valve 304. The outlet of back pressure valve 304 and the outlet of back pressure valve 305 merge and are then regulated before being connected to the user unit.

[0054] The nitrogen expansion precooling section is described in the nitrogen expansion precooling system above.

[0055] The outlet of hydrogen compressor 2 (103) is connected to the inlet of check valve 1 (104). The outlet of check valve 1 (104) is connected to the inlet of cooler 2 (105). The outlet of cooler 2 (105) is connected to the inlet of first heat exchanger A (A4) (at the start of the LNG precooling section). The outlet of first heat exchanger A (A3) splits into two paths. The first path outlet is connected to the inlet of second heat exchanger B (B4). The outlet of second heat exchanger B (B3) is connected to the inlet of third heat exchanger C (C4) (at the end of the LNG precooling section, the nitrogen expansion precooling section begins). The outlet of the third heat exchanger C, C3, is divided into two paths. The first path is connected to the inlet of the fourth heat exchanger D, D4 (end of the nitrogen expansion precooling section). The outlet of the fourth heat exchanger D, D3, is connected to the inlet of throttle valve 110, and the outlet of throttle valve 110 is connected to the inlet of liquid hydrogen storage tank 111. The second path of the third heat exchanger C is connected to the inlet of shut-off valve 108, and the outlet of shut-off valve 108 is connected to the inlet of turbine expander 109. Turbine expander 109 is connected to a generator. The outlet of turbine expander 109 (machine 3) merges with the outlet of liquid hydrogen storage tank 111 and is then connected to the D2 inlet of fourth heat exchanger D. The D1 outlet of fourth heat exchanger D is connected to the C2 inlet of third heat exchanger C. The second path of the A3 outlet of first heat exchanger A is connected to the inlet of shut-off valve 106. The outlet of shut-off valve 106 is connected to the inlet of turbine expander 107. Turbine expander 107 is connected to generator 113. The outlet of turbine expander 107... After the end of the first heat exchanger C merges with the C1 outlet end of the third heat exchanger C, it is connected to the B2 inlet end of the second heat exchanger B. The B1 outlet end of the second heat exchanger B is connected to the A2 inlet end of the first heat exchanger A. The A1 outlet end of the first heat exchanger A is connected to the control unit 100, and then connected to the inlet end of the hydrogen compressor 101. The outlet end of the hydrogen compressor 101 is connected to the inlet end of the cooler 102. The outlet end of the cooler 102 merges with the outlet end of the shut-off valve 208 and is connected to the hydrogen compressor 203.

[0056] The electrical energy generated by generators 213 and 319 is combined with the electrical energy generated by generator 1309 and then enters the electrolytic cell 205 through inverter 201, thus entering the next cycle.

[0057] The control unit 100 receives the pressure, temperature and flow values ​​of the system measurement section, and adjusts the opening of shut-off valves 106 and 108, throttle valve 110, ball valve 303 and 118, and the speed of hydrogen compressor 101, hydrogen compressor 2103 and nitrogen compressor 116 to ensure that the system operates normally within the set parameter range.

[0058] The control unit 100 collects measurement point data and then adjusts the devices and actuators in each module to ensure the safe and stable operation of the system.

[0059] The parameters set at the temperature and pressure measuring points and control unit 100 distributed in each system are as follows: hydrogen pressure a(P1), e(P2), f(P3), g(P4); hydrogen temperature b(T1), c(T2), h(T3), i(T4);

[0060] The specific adjustment method is as follows:

[0061] By adjusting the speed of hydrogen compressor 2 103, hydrogen compressor 101, and nitrogen compressor 116, the pressures at points a, f, and g are controlled to reach the set values ​​P1, P3, and P4, respectively. By detecting the pressure values ​​at points d and e, hydrogen compressor 101 is controlled to make the pressure values ​​at points d and e equal.

[0062] By adjusting the opening of ball valve 2 303, throttle valve 110, ball valve 4 118, shut-off valve 4 108, and shut-off valve 3 106, the temperatures at points b, c, h, and i are controlled to reach the set values ​​T1, T2, T3, and T4, respectively.

[0063] The first heat exchanger A, the second heat exchanger B, the third heat exchanger C, and the fourth heat exchanger D are all microchannel plate-fin heat exchangers. Among them, the microchannels of the second heat exchanger B, the third heat exchanger C, and the fourth heat exchanger D are filled with positive and negative hydrogen conversion catalyst particles.

[0064] The nitrogen replenishment tank 117 in the nitrogen expansion precooling system replenishes nitrogen for this cycle to balance the pressure within the cycle.

[0065] The electrolyzer 205 of the water electrolysis hydrogen production system produces hydrogen by electrolyzing water through alkaline hydrolysis, proton exchange membrane hydrolysis, and high-temperature solid oxide hydrolysis.

[0066] The deoxygenation drying device 206 uses the principle of reacting with oxygen to produce water, thereby obtaining the desired gas through deoxygenation and purification.

[0067] The working fluid in an LNG cold power generation system can be one of propane, trifluoromethane, ethylene, or a mixture of working fluids.

[0068] Coolers 102, 105, and 115 are water-cooled, and flow meters 302 and 207 are Venturi flow meters.

[0069] The operating method of the above-mentioned self-powered LNG cold energy used for hydrogen production and hydrogen liquefaction co-production unit and control method specifically includes:

[0070] LNG at -165℃ leaves the LNG storage tank, is pressurized to 7.3MPa by submersible pump 1, and then enters flow meter 1. Flow meter 1 divides the flow meter into two paths. The first path enters LNG vaporizer H through ball valve 1 to release cold energy and exchanges heat with propane, the working fluid in the power generation cycle system. At this time, the propane pressure is 0.1MPa and the temperature is -43.5℃. The propane is then pressurized to 0.55MPa by the working fluid pump and enters the sixth heat exchanger F to exchange heat with cooling water at 0.3MPa and 18.8℃. At this time, the propane temperature rises to 3.6℃ and enters turbine expander 3, which drives generator 1 to work and generate electricity. The propane pressure exiting turbine expander 3 is 0.1MPa and the temperature is -41.8℃. It then enters the LNG vaporizer to continue exchanging heat with LNG and enters the next power generation cycle.

[0071] The electrical energy generated by generator 1 enters the alkaline electrolyzer via an inverter. The oxygen generated by the alkaline electrolyzer enters the oxygen storage tank through shut-off valve 1. The hydrogen generated by the alkaline electrolyzer enters the deoxygenation drying unit for purification. The purified hydrogen has a pressure of 0.3 MPa. The raw water is replenished by ball valve 3 to supplement the raw water consumed in the hydrogen production process. The purified hydrogen enters shut-off valve 2 through flow meter 2, and then enters hydrogen compressor 2 to be pressurized to 2.5 MPa. It then enters check valve 1, is cooled to 20°C by cooler 2, and enters the LNG precooling section. After that, it is cooled to -85°C and -145°C by the first heat exchanger A and the second heat exchanger B, respectively.

[0072] In the LNG precooling section, LNG at 7.4MPa and -165℃ enters the second heat exchanger B through the second outlet of flow meter one, passes through ball valve two, and then enters the first heat exchanger A, where the temperature rises to -105℃. The temperature is then further increased to 10℃, and the pressure is stabilized by back pressure valve two.

[0073] After passing through LNG vaporizer H, the LNG becomes NG at -51.8℃. It then enters the fifth heat exchanger E and exchanges heat with cooling water at 0.3MPa and 18.8℃. The NG temperature further increases to 13.8℃. It then enters back pressure valve one to stabilize the pressure. After the back pressure valve two and the outlet of back pressure valve one merge, the NG pressure is adjusted to 2.3MPa and finally enters the user end for user use.

[0074] After the LNG precooling section ends, hydrogen enters the nitrogen expansion precooling section and is cooled to -190℃ by the third heat exchanger C.

[0075] In the nitrogen expansion precooling section, nitrogen enters nitrogen compressor one and is pressurized to 3.5 MPa. After passing through check valve two, it enters cooler three and is cooled to 20°C. Then, it enters the first heat exchanger A and is cooled to -85°C, and the second heat exchanger B and is cooled to -145°C. Finally, it enters the expansion end of the turbocharger to expand and do work. At this time, the nitrogen pressure is 1.5 MPa and the temperature is -194°C. The nitrogen coming out of the expansion end of the turbocharger enters the third heat exchanger C, the second heat exchanger B, and the first heat exchanger A in sequence to be reheated to -150°C, -90°C, and 10°C, respectively. Then, it enters the booster end of the turbocharger and is pressurized to 2.7 MPa. To ensure the normal operation of the circulation pressure, nitrogen at 2.7 MPa and 25°C from the nitrogen replenishment tank passes through ball valve four to replenish the circulation nitrogen. It merges with the nitrogen coming out of the booster end of the turbocharger and enters nitrogen compressor one to be pressurized to 3.5 MPa, and then enters the next cycle.

[0076] Hydrogen gas cooled in the first heat exchanger A is divided into two paths. The first path passes through the second heat exchanger B and the third heat exchanger C, where it is cooled to -145°C and -190°C respectively. Hydrogen gas cooled in the third heat exchanger C is divided into two paths. The first path passes through the fourth heat exchanger D, where it is cooled to -240°C. It then enters the throttle valve for further cooling to -253°C, where the hydrogen gas is liquefied and then enters the liquid hydrogen storage tank.

[0077] After being cooled in the third heat exchanger C, the second outlet of the hydrogen enters the second turbine expander through the fourth shut-off valve and is cooled to -243°C. The pressure drops to 0.1 MPa, which drives the third generator to generate electricity. Then, it merges with the low-temperature hydrogen from the liquid hydrogen storage tank and enters the fourth heat exchanger D and the third heat exchanger C in sequence for reheating.

[0078] After being cooled in the first heat exchanger A, the second outlet of the hydrogen enters the first turbine expander through the third shut-off valve, where it is cooled to -150°C and the pressure drops to 0.1 MPa. This drives the second generator to produce electricity. The hydrogen then merges with the hydrogen that has been reheated in the third heat exchanger C and enters the second heat exchanger B and the first heat exchanger A in sequence for reheating. It then enters the first hydrogen compressor and is pressurized to 0.3 MPa. After entering the first cooler, it is cooled to 20°C and merges with the hydrogen that comes out from the second shut-off valve. It then enters the second hydrogen compressor and is pressurized to 2.5 MPa, starting the next cycle.

[0079] The electrical energy generated by generators two and three is combined with the electrical energy generated by generator one and then enters the alkaline electrolyzer through the inverter to electrolyze water to produce hydrogen, thus entering the next cycle;

[0080] The parameters set by the control unit 100 are as follows: the pressure at measurement point a is set to P1, the temperature at measurement point b is set to T1, the temperature at measurement point c is set to T2, the pressure at measurement point e is set to P2, the pressure at measurement point f is set to P3, the pressure at measurement point g is set to P4, the temperature at measurement point h is set to T3, and the temperature at measurement point i is set to T4.

[0081] like Figure 2 As shown, the hydrogen pressure at point a is controlled by the second speed of the hydrogen compressor to a set value P1, where P1 = 2.5 MPa. For example, when the measured pressure p1 > P1, the hydrogen pressure is reduced to P1 by decreasing the second speed of the hydrogen compressor.

[0082] like Figure 3 As shown, the hydrogen temperature at point b is controlled by the second opening of the ball valve to a set value T1, where T1 = -145℃. For example, when the measured temperature t1 > T1, the hydrogen temperature is reduced to T1 by increasing the second opening of the ball valve.

[0083] like Figure 4 As shown, the hydrogen temperature at point c is controlled by the opening of the throttle valve to a set value T2, where T2 = -253℃. For example, when the measured temperature t2 > T2, the hydrogen temperature is reduced to T2 by increasing the opening of the throttle valve.

[0084] like Figure 5 As shown, the hydrogen pressure at point d is controlled by the speed of the hydrogen compressor to a set value P2, where P2 = 0.3 MPa. For example, when the measured pressure p2 > P2, the hydrogen pressure is reduced to P2 by decreasing the speed of the hydrogen compressor.

[0085] like Figure 6 As shown, the nitrogen pressure at point f is controlled by the speed of the nitrogen compressor to a set value P3, where P3 = 3.5 MPa. For example, when the measured pressure p3 > P3, the nitrogen pressure is reduced to P3 by decreasing the speed of the nitrogen compressor.

[0086] like Figure 7 As shown, the nitrogen pressure at point g is controlled by the opening of the ball valve to a set value P4, where P4 = 2.7 MPa. For example, when the measured pressure p4 > P4, the nitrogen pressure is reduced to P4 by decreasing the opening of the ball valve.

[0087] like Figure 8 As shown, the hydrogen temperature at point h is controlled by the three-degree opening of the shut-off valve to a set value T3, where T3 = -243℃. For example, when the measured pressure t3 > T3, the hydrogen temperature is reduced to T3 by increasing the three-degree opening of the shut-off valve.

[0088] like Figure 9As shown, the hydrogen temperature at point i is controlled by the opening degree of the shut-off valve to a set value T4, where T4 = -150℃. For example, when the measured pressure t4 > T4, the hydrogen temperature is reduced to T4 by increasing the opening degree of the shut-off valve.

Claims

1. A self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device, characterized in that: The LNG gasification power generation system, the self-power generation water electrolysis hydrogen production system, the nitrogen expansion pre-cooling system, and the hydrogen pressurization liquefaction system are included. The LNG storage tank (301) of the LNG gasification power generation system is connected to the inlet end of the submersible pump (310), the outlet end of the submersible pump (310) is connected to the inlet end of the flowmeter (302), the outlet end of the flowmeter (302) is connected to the hydrogen pressurization liquefaction system and the inlet end of the ball valve (306) in two ways, the outlet end of the ball valve (306) is connected to the H1 inlet end of the LNG gasifier H, the H3 outlet end of the LNG gasifier H is connected to the inlet end of the working medium pump (307), the outlet end of the working medium pump (307) is connected to the F1 inlet end of the sixth heat exchanger F, the F3 outlet end of the sixth heat exchanger F is connected to the inlet end of the turbine expander three (308), the turbine expander three (308) is connected to the generator (309), the outlet end of the turbine expander three (308) is connected to the H2 inlet end of the LNG gasifier H, the H4 outlet end of the LNG gasifier H is connected to the E3 inlet end of the fifth heat exchanger E, and the E2 outlet end of the fifth heat exchanger E is connected to the inlet end of the back pressure valve (305); The inverter (201) of the self-power generation water electrolysis hydrogen production system is connected to the X1 inlet end of the electrolytic cell (205), the raw water is connected to the inlet end of the ball valve three (202), the outlet end of the ball valve three (202) is connected to the X2 inlet end of the electrolytic cell (205), the X4 outlet end of the electrolytic cell (205) is connected to the inlet end of the stop valve (204), the outlet end of the stop valve (204) is connected to the inlet end of the oxygen storage tank (203), the X3 outlet end of the electrolytic cell (205) is connected to the inlet end of the deoxidizing drying device (206), the outlet end of the deoxidizing drying device (206) is connected to the inlet end of the flowmeter two (207), the outlet end of the flowmeter two (207) is connected to the stop valve two (208), and the stop valve two (208) is connected to the hydrogen pressurization liquefaction system; The nitrogen compressor one (116) of the nitrogen expansion pre-cooling system is connected to the inlet end of the check valve two (114), the outlet end of the check valve two (114) is connected to the inlet end of the cooler three (115), the outlet end of the cooler three (115) is connected to the hydrogen pressurization liquefaction system, and the hydrogen pressurization liquefaction system is connected to the Y1 inlet end of the expansion end of the turbine pressurizer (112) through the hydrogen pressurization liquefaction system, the Y2 outlet end of the expansion end of the turbine pressurizer (112) is connected to the Y4 inlet end of the pressurization end of the turbine pressurizer (112) through the hydrogen pressurization liquefaction system, and the Y3 outlet end of the pressurization end of the turbine pressurizer (112) is connected to the inlet end of the nitrogen compressor one (116); The hydrogen in the hydrogen pressurization liquefaction system is sequentially treated through the LNG pre-cooling section, the nitrogen expansion pre-cooling section, and the turbine expander cooling section, and then enters the liquid hydrogen storage tank (111) for storage through the throttle valve (110). The LNG pre-cooling section is provided with LNG by a LNG gasification power generation system, a flowmeter one (302) is connected with the hydrogen pressurized liquefaction system through a ball valve two (303), the ball valve two (303) is connected with the B10 inlet end of a second heat exchanger B, the B9 outlet end of the second heat exchanger B is connected with the A10 inlet end of a first heat exchanger A, the A9 outlet end of the first heat exchanger A is connected with the inlet end of a back pressure valve two (304), the outlet end of the back pressure valve two (304) is connected with the outlet end of a back pressure valve one (305), after being adjusted and treated, the outlet end of the back pressure valve one (305) is connected with a user unit; the hydrogen compressor two (103) of the LNG pre-cooling section is connected with the inlet end of a check valve one (104), the outlet end of the check valve one (104) is connected with the inlet end of a cooler two (105), the outlet end of the cooler two (105) is connected with the A4 inlet end of the first heat exchanger A, the A3 outlet end of the first heat exchanger A is connected with the B4 inlet end of the second heat exchanger B, the B3 outlet end of the second heat exchanger B is connected with the C4 inlet end of a third heat exchanger C; The nitrogen expansion pre-cooling section is provided with N2 by a nitrogen expansion pre-cooling system, the C4 inlet end of the third heat exchanger C of the nitrogen expansion pre-cooling section is connected with the B3 outlet end of the second heat exchanger B; The D4 inlet end of a fourth heat exchanger D of the turbine expander cooling section is connected with the C3 outlet end of the third heat exchanger C, the D3 outlet end of the fourth heat exchanger D is connected with the inlet end of a throttle valve (110), the outlet end of the throttle valve (110) is connected with the inlet end of a liquid hydrogen storage tank (111), a stop valve four (108) is connected with the C3 outlet end of the third heat exchanger C, the outlet end of the stop valve four (108) is connected with the inlet end of a turbine expander two (109), the turbine expander two (109) is connected with a generator three (119), the outlet end of the turbine expander two (109) is connected with the outlet end of the liquid hydrogen storage tank (111), and the outlet end of the turbine expander two (109) and the outlet end of the liquid hydrogen storage tank (111) are connected with the D2 inlet end of the fourth heat exchanger D, and the D1 outlet end of the fourth heat exchanger D is connected with the C2 inlet end of the third heat exchanger C.

2. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 1, characterized in that: The A3 outlet end of the first heat exchanger A is also connected with the inlet end of a stop valve three (106), the outlet end of the stop valve three (106) is connected with the inlet end of a turbine expander one (107), the turbine expander one (107) is connected with a generator two (113), the outlet end of the turbine expander one (107) is connected with the C1 outlet end of the third heat exchanger C, the outlet end of the turbine expander one (107) and the C1 outlet end of the third heat exchanger C are connected with the B2 inlet end of the second heat exchanger B, the B1 outlet end of the second heat exchanger B is connected with the A2 inlet end of the first heat exchanger A, and the electric energy generated by the generator two (113), the generator one (309) and the generator three (119) is combined and input into an electrolytic cell (205) through an inverter (201) in a reciprocating cycle.

3. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 2, characterized in that: The B1 outlet end of the second heat exchanger B is connected with the A2 inlet end of the first heat exchanger A, and then the A1 outlet end of the first heat exchanger A is connected with the inlet end of the hydrogen compressor one (101), the outlet end of the hydrogen compressor one (101) is connected with the inlet end of the cooler one (102), and the outlet end of the cooler one (102) is connected with the outlet end of the stop valve two (208) and then connected with the hydrogen compressor two (103).

4. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 3, characterized in that: The control unit (100) is further included, the control unit (100) is connected between the A1 outlet end of the first heat exchanger A and the inlet end of the hydrogen compressor one (101), and the hydrogen compressor two (103), the nitrogen compressor one (116), the ball valve two (303), the throttle valve (110), the ball valve four (118), the stop valve four (108) and the stop valve three (106) are respectively connected with the control unit (100) in signal connection.

5. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 1, characterized in that: The nitrogen expansion pre-cooling system further includes the nitrogen supplement tank (117), the outlet end of the nitrogen supplement tank (117) is connected with the inlet end of the ball valve four (118), the outlet end of the ball valve four (118) is connected with the Y3 outlet end of the turbo supercharger (112) in the pressurization end, and then connected with the inlet end of the nitrogen compressor one (116); The outlet end of the cooler three (115) is connected with the A7 inlet end of the first heat exchanger A, the A8 outlet end of the first heat exchanger A is connected with the B7 inlet end of the second heat exchanger B, the B8 outlet end of the second heat exchanger B is connected with the Y1 inlet end of the turbo supercharger (112) in the expansion end, the Y2 outlet end of the turbo supercharger (112) in the expansion end is connected with the C6 inlet end of the third heat exchanger C, the C5 outlet end of the third heat exchanger C is connected with the B6 inlet end of the second heat exchanger B, the B5 outlet end of the second heat exchanger B is connected with the A6 inlet end of the first heat exchanger A, and the A5 outlet end of the first heat exchanger A is connected with the Y4 inlet end of the turbo supercharger (112) in the pressurization end.

6. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 1, characterized in that: The first heat exchanger A, the second heat exchanger B, the third heat exchanger C and the fourth heat exchanger D are all micro-channel plate fin heat exchangers, wherein the second heat exchanger B, the third heat exchanger C and the fourth heat exchanger D are filled with primary and secondary hydrogen conversion catalytic particles in the micro-channels.

7. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 1, characterized in that: The electrolytic tank (205) electrolyzes water to produce hydrogen by the methods of alkaline hydrolysis, proton exchange membrane hydrolysis and high-temperature solid oxide hydrolysis; and the deoxidization drying device (206) adopts the method of reacting with oxygen to generate water, and obtains the required gas by deoxidization purification.

8. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 1, characterized in that: The working medium in the LNG cold energy power generation system is propane, trifluoromethane or ethylene.

9. The self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device according to claim 3, characterized in that: The cooler one (102), the cooler two (105) and the cooler three (115) are water-cooled coolers, and the flowmeter one (302) and the flowmeter two (207) are Venturi flowmeters.

10. A method of operating a self-powered LNG cold energy for hydrogen production and hydrogen liquefaction cogeneration device as claimed in any one of claims 1 to 9, characterized in that The method comprises the following steps: The B1 outlet end of the second heat exchanger B is connected with the A2 inlet end of the first heat exchanger A, and then the A1 outlet end of the first heat exchanger A is connected with the inlet end of the hydrogen compressor one (101), the outlet end of the hydrogen compressor one (101) is connected with the inlet end of the cooler one (102), and the outlet end of the cooler one (102) is connected with the outlet end of the stop valve two (208) and then connected with the hydrogen compressor two (103). First step: open the device, LNG in LNG storage tank (301) through the submerged pump one (310) into the flowmeter one (302), flowmeter one (302) outlet end is divided into two ways, the first way through the ball valve one (306) into LNG gasifier H release cold energy, with the working medium of power generation cycle system heat exchange, working medium through working medium pump (307) booster, into the sixth heat exchanger F and cooling water heat exchange, working medium temperature rises, into the turbine expander three (308), drive generator one (309) work, produce electric energy; the second road of flowmeter one (302) outlet after through ball valve two (303) into the second heat exchanger B heat exchange, temperature rises, then into the first heat exchanger A, temperature further rises, through back pressure valve two (304) stable pressure, after LNG gasifier H LNG becomes NG, temperature rises, further into the fifth heat exchanger E and cooling water heat exchange, NG temperature further rises, into back pressure valve one (305) stable pressure, back pressure valve two (304) and back pressure valve one (305) outlet one and merge after, after adjusting processing into user end; Second step: the electric energy generated by generator one (309) through inverter (201) into electrolytic cell (205), the oxygen generated by electrolytic cell (205) through stop valve one (204) into oxygen storage tank (203); Hydrogen produced by electrolytic cell (205) into deoxidizing drying device (206) for hydrogen purification, raw water through ball valve three (202) to supplement the raw water consumed in the process of electrolytic water preparation hydrogen, after purification, hydrogen through flowmeter two (207) into stop valve two (208), then into hydrogen compressor two (103) booster, into check valve one (104), after cooling cooler two (105) into LNG precooling section, in turn through the first heat exchanger A, second heat exchanger B cooling; Third step: nitrogen into nitrogen expansion precooling section; Nitrogen from nitrogen compressor one (116) booster, after check valve two (114) into cooler three (115) cooling, then into the first heat exchanger A, second heat exchanger B cooling, into turbine booster (112) expansion; From turbine booster (112) out of nitrogen in turn into third heat exchanger C, second heat exchanger B, first heat exchanger A, after entering turbine booster (112) booster into nitrogen compressor one (116) booster, into the next cycle; Fourth step: after LNG precooling section hydrogen into nitrogen expansion precooling section, through the third heat exchanger C cooling; Fifth step: after nitrogen expansion precooling section into turbine expander cooling section, from the third heat exchanger C hydrogen after cooling, the first way through the fourth heat exchanger D cooling, into the throttle valve (110) further cooling, then into liquid hydrogen storage tank (111); The second way through stop valve four (108) into turbine expander two (109) cooling, drive generator three (303) operation, produce electric energy, then with the low temperature hydrogen from liquid hydrogen storage tank (111) merge into in turn into fourth heat exchanger D, third heat exchanger C reheat; The hydrogen gas of the second path after being cooled in the first heat exchanger A enters turbine expander I (107) to be cooled, drives generator II (113) to operate and generate electric energy, which is transmitted to the electrolytic cell (205), and then is mixed with the hydrogen gas after being re-heated in the third heat exchanger C, and then enters the second heat exchanger B, the first heat exchanger A in sequence to be re-heated, and then enters the hydrogen compressor I (101) to be pressurized, enters the cooler I (102) to be cooled, is mixed with the hydrogen gas from the stop valve II (208), enters the hydrogen compressor II (103) to be pressurized, and enters the next cycle.

Images