A marine methanol-water reforming hydrogen production proton exchange membrane fuel cell system

Abstract

The present invention provides a marine methanol water reforming hydrogen production proton exchange membrane fuel cell system, comprising an external water production system, a reforming separation system, a purification condensation system and a proton exchange membrane fuel cell connected in sequence, wherein the external water production system is used to produce fresh water from seawater based on a reverse osmosis device; the reforming separation system is used to reform methanol water vapor mixed with fresh water and methanol, and to separate the reformed mixed gas; the purification condensation system is used to purify and condense the hydrogen obtained after separation to produce pure hydrogen; and the proton exchange membrane fuel cell is used to consume the produced hydrogen and oxygen to generate electricity. The present invention purifies seawater by using a reverse osmosis method, so that seawater is used as a water source in a methanol water reforming hydrogen production reaction. The reforming hydrogen production reaction is then used to provide fuel for the proton exchange membrane fuel cell. The safety, cost and space problems caused by water storage and hydrogen storage on ships are solved, and the entire system makes full use of raw materials.

Description

Technical Field

[0001] The invention relates to the fields of reverse osmosis water production, methanol-water reforming hydrogen production and proton exchange membrane fuel cells, and in particular to a marine methanol-water reforming hydrogen production proton exchange membrane fuel cell system. Background Art

[0002] Methanol water reforming hydrogen production technology is a hydrogen production technology that emerged in the 1980s. Canada, the United Kingdom and other countries have conducted a lot of research in this regard, so the technology is relatively mature in terms of process and has become a good choice for hydrogen fuel cell power devices. This technology mixes methanol and pure fresh water in a certain proportion, heats and vaporizes them and superheats them to reach a certain pressure and temperature for reforming reaction. Fresh water and methanol are mixed and pressurized and sent to the heat exchanger for preheating, and then enter the superheater for vaporization and superheating to the required temperature. The superheated methanol water gas completes the two reactions of gas-phase catalytic cracking and conversion under the action of the catalyst in the reformer to generate a mixed gas containing CO2, H2, and CO.

[0003] A fuel cell is an energy conversion device controlled by electrochemical principles, that is, the working principle of a primary cell, which directly converts the chemical energy stored in the fuel and oxidant into electrical energy isothermally, so that the actual process is still a redox reaction. Theoretically, the reason why fuel cells are very economical in the international market is that they can even achieve a thermal efficiency of nearly 100% during operation. At present, the various types of fuel cells that can be used in practice are limited by factors such as hydrogen transportation, storage and transportation energy consumption, and considering the energy consumption of the device or the entire system, so the total conversion efficiency of the general fuel cell system is mostly in the range of 40% to 60%. However, if the use of exhaust heat is considered, the total conversion efficiency can be more than 80% after different optimization treatments. Proton exchange membrane fuel cell: Proton exchange membrane fuel cell, referred to as PEMFC, is composed of a cathode, an anode and a proton exchange membrane. Its power generation process does not involve the combustion of hydrogen and oxygen, so it is not limited by the Carnot cycle. It has a high energy conversion rate and its emissions are water and water vapor, which is basically zero pollution. The power generation unit is modular, highly reliable, easy to assemble and maintain, and has no mechanical vibration, low noise and low heat radiation. It is a clean and efficient green energy, so it is a fuel cell with good development prospects.

[0004] Reverse osmosis (RO) is a membrane separation and filtration technology that uses pressure difference as a driving force. Its pore size is as small as nanometers. Under a certain pressure, water molecules can pass through the RO membrane, while other substances in seawater, such as inorganic salts, heavy metal ions, organic matter, bacteria and impurities, cannot pass through. However, the osmotic pressure of seawater is greater than that of fresh water, so external pressure needs to be applied to the seawater to achieve the purpose of filtering seawater.

[0005] At present, for small and medium-sized ships, due to the small space, they cannot carry a large amount of hydrogen as fuel for proton exchange membrane fuel cells. At the same time, a large amount of fresh water source is required. Due to the many difficulties that need to be overcome, the development of marine fuel cells is slow. Summary of the invention

[0006] According to the technical problems raised above, a marine methanol water reforming hydrogen production proton exchange membrane fuel cell system is provided. The present invention mainly utilizes the methanol water reforming hydrogen production technology to produce hydrogen, and combines the reverse osmosis water production technology to produce fresh water. Therefore, this system can better make up for the problems caused by hydrogen transportation and storage and the defect that small and medium-sized ships cannot carry a large amount of fresh water. It also combines the advantages of the three technologies, so that this system is very promising as a ship power system device. The technical means adopted by the present invention are as follows:

[0007] A marine methanol-water reforming hydrogen production proton exchange membrane fuel cell system comprises an external water production system, a reforming separation system, a purification condensation system and a proton exchange membrane fuel cell which are connected in sequence.

[0008] The external water production system is used to produce fresh water from seawater based on reverse osmosis equipment;

[0009] The reforming and separation system is used to reform methanol water vapor mixed with fresh water and methanol and separate hydrogen from the reformed mixed gas;

[0010] The purification condensation system is used to condense the hydrogen obtained after methanol steam reforming and separation to produce pure hydrogen;

[0011] The proton exchange membrane fuel cell is used to consume the produced hydrogen and oxygen to generate electricity.

[0012] Furthermore, the external fresh water production system includes a reverse osmosis fresh water generator, a methanol storage device, a fresh water storage device, a mixer, and a valve group. The input end of the reverse osmosis fresh water generator is connected to seawater, the output end of the reverse osmosis fresh water generator is connected to the mixer through the fresh water storage device, the output end of the methanol storage device is also connected to the mixer, and the output end of the mixer is connected to the reforming separation system through the valve group.

[0013] Furthermore, the temperature of each device in the external water production system is room temperature and the pressure is 1 atm.

[0014] Furthermore, the reforming and separation system includes a superheater, an autothermal reformer, and a separator, wherein the autothermal reformer divides methanol into two parts, one part is used for combustion to provide the heat required for reforming, and the other part is used for reforming to produce hydrogen, which is cracked and converted into a mixed gas of hydrogen and carbon oxides, and then the hydrogen and other gases are separated through the separator.

[0015] Furthermore, the purification and condensation system includes a purifier and a condenser, the purifier is connected to the output end of the separator, the purifier is used to purify the gas output by the separator to remove impurities, the condenser is connected to the output end of the purifier, the condenser is used to remove moisture in the hydrogen, and the condenser is also connected to the mixer, the condensed water output by the condenser flows back to the mixer and continues to mix with methanol to carry out the next process.

[0016] Furthermore, the proton exchange membrane fuel cell includes an oxygen input end and a hydrogen input end, the hydrogen input end is connected to the outlet of the condenser, and the proton exchange membrane fuel cell is also connected to the output end of the purifier, and the cathode water outputted by the proton exchange membrane fuel cell is used as the supply of the purifier.

[0017] The present invention uses reverse osmosis to purify seawater so that seawater is used as a water source in the methanol-water reforming hydrogen production reaction. The reforming hydrogen production reaction is then used to provide fuel for the proton exchange membrane fuel cell. These two aspects solve the safety, cost and space problems caused by water storage and hydrogen storage on ships. The entire system makes full use of raw materials through various methods, and also improves the overall raw material utilization rate of the system. On ships, when using hydrogen fuel proton exchange membrane fuel cells, the storage problem of hydrogen must be considered. Due to its own properties, the storage cost of hydrogen is relatively high. Using methanol water vapor reforming to produce hydrogen can effectively avoid this problem. The present invention can combine water production technology, methanol water reforming technology and proton exchange membrane batteries, so that ships do not need to carry a large amount of fresh water resources, and also solve the problem that although hydrogen is a very clean energy source, its transportation and storage costs are very high and it has very serious safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 This is a system structure diagram of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, the present invention discloses a marine methanol-water reforming hydrogen production proton exchange membrane fuel cell system, comprising an external water production system, a reforming separation system, a purification condensation system and a proton exchange membrane fuel cell connected in sequence.

[0022] The external water making system is used to make fresh water from seawater based on reverse osmosis equipment. Ships cannot carry a large amount of water resources. The external water making part avoids the problem of the source of water for ships. Combined with the reverse osmosis water making technology, fresh water can be made from existing resources anytime and anywhere to supply the reforming reaction, saving space and transportation costs.

[0023] The reforming and separation system is used to reform methanol water vapor mixed with fresh water and methanol and separate hydrogen from the reformed mixed gas;

[0024] The purification and condensation system is used to purify and condense the hydrogen obtained after methanol steam reforming and separation to produce pure hydrogen;

[0025] The proton exchange membrane fuel cell is used to consume the produced hydrogen and oxygen to generate electricity.

[0026] The present invention first uses the reverse osmosis method to filter seawater to produce fresh water. In the embodiment of the present invention, the daily water production of the large ship fresh water generator can reach about 20 tons, wherein a part of the water is desalted to remove the calcium and magnesium ions therein, and then the desalted water and methanol are mixed in a molar ratio of 1.0-5.0 and passed through a valve group into a preheating and superheating device to preheat the mixed liquid to 300°C. Then the superheated vaporized mixed gas is passed into an autothermal reformer for reforming, and cracked and converted into a mixed gas of hydrogen and carbon oxides. The valve group controls the flow of methanol water vapor through the feedback of the fuel cell feedback device, thereby controlling the flow of hydrogen in the mixer manufactured by the autothermal reformer. Afterwards, at a temperature of 250-350°C, the mixed gas is separated by a hydrogen purification device (using a pressure swing adsorption and a palladium membrane separation device). The separated hydrogen is passed into the purifier for purification. In the preferred embodiment of the present invention, the purity of hydrogen after this process can reach 99.9%-99.999%, which can fully meet the requirements of fuel cells for hydrogen purity; the purified hydrogen is then passed into the condenser to reduce its temperature to 40°C. The reflux liquid phase is mainly condensed water, which continues to flow back to the mixer for the next process flow. Pure hydrogen continues to pass into the anode of the proton exchange membrane fuel cell and reacts with the oxygen at the cathode, and finally produces electricity for use by the ship's power system.

[0027] Specifically, the external fresh water system includes a reverse osmosis fresh water generator, a methanol storage device, a fresh water storage device, a mixer, and a valve group. The input end of the reverse osmosis fresh water generator is connected to seawater, the output end of the reverse osmosis fresh water generator is connected to the mixer through the fresh water storage device, the output end of the methanol storage device is also connected to the mixer, and the output end of the mixer is connected to the reforming separation system through the valve group. The temperature of each device in the external fresh water system is room temperature and the pressure is 1atm.

[0028] The reforming and separation system includes an autothermal reformer and a separator, wherein the autothermal reformer divides methanol into two parts, one part is used for combustion to provide heat required for reforming, and the other part is used for reforming to produce hydrogen, which is cracked and converted into a mixed gas of hydrogen and carbon oxides (CO, CO2), and then the hydrogen and other gases are separated by the separator. In the embodiment of the present invention, the theoretical hydrogen yield of methanol is 18.8% (mass fraction).

[0029] The purification condensation system includes a purifier and a condenser. The purifier is connected to the output end of the separator. The purifier is used to purify the gas output by the separator to remove impurities. The condenser is connected to the output end of the purifier. The condenser is used to remove moisture in the hydrogen. The condenser is also connected to the mixer. The condensed water output by the condenser flows back to the mixer and continues to be mixed with methanol to carry out the next process, thereby improving the utilization rate of the raw materials.

[0030] The proton exchange membrane fuel cell comprises an oxygen input end and a hydrogen input end, wherein the hydrogen input end is connected to the outlet of the condenser. The proton exchange membrane fuel cell is also connected to a purifier, and its cathode water is used as supply for the purifier.

[0031] Large ship water generators can produce 20 tons of fresh water every day, so this technology can fully provide sufficient fresh water for methanol water reforming hydrogen production reaction, and the present invention controls the flow of the mixer output through the valve group, thereby controlling the flow of hydrogen after reforming and purification, so that the hydrogen flow of the fuel cell anode inlet can be controlled. When the load becomes larger, the valve group and other equipment can be used to increase the flow of the mixer output, and then control the amount of hydrogen to avoid excessive hydrogen production and danger, and also avoid the fuel cell load being too large and damaged. When the maximum load power on the ship is 50kw and the single-chip battery voltage is 0.7v, the fuel cell needs a hydrogen flow of 2.7kg / h at this time. When the hydrogen flow exceeds this value, the feedback device feeds back the hydrogen flow to the valve group, thereby controlling the hydrogen production of the autothermal reformer. The present invention combines reverse osmosis water making technology, methanol water vapor reforming technology and proton exchange membrane fuel cell technology, and gives full play to the advantages of the three different technologies. According to the above summary, the combination of reverse osmosis water production, methanol water reforming hydrogen production and proton exchange membrane fuel cell technology as a ship power system is very promising.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A marine methanol water reforming hydrogen production proton exchange membrane fuel cell system, characterized in that: It includes an external water production system, a reforming separation system, a purification condensation system and a proton exchange membrane fuel cell which are connected in sequence. The external water production system is used to produce fresh water from seawater based on reverse osmosis equipment; The reforming and separation system is used to reform methanol water vapor mixed with fresh water and methanol and separate hydrogen from the reformed mixed gas; The purification and condensation system is used to purify and condense the hydrogen obtained after methanol steam reforming and separation to produce pure hydrogen; The proton exchange membrane fuel cell is used to consume the produced hydrogen and oxygen to generate electricity; The external fresh water system includes a reverse osmosis fresh water generator, a methanol storage device, a fresh water storage device, a mixer, and a valve group. The input end of the reverse osmosis fresh water generator is connected to seawater, the output end of the reverse osmosis fresh water generator is connected to the mixer through the fresh water storage device, the output end of the methanol storage device is also connected to the mixer, and the output end of the mixer is connected to the reforming separation system through the valve group. The temperature of each device in the external water production system is room temperature and the pressure is 1atm.

2. The marine methanol water reforming hydrogen production proton exchange membrane fuel cell system according to claim 1 is characterized in that: The reforming and separation system includes a superheater, an autothermal reformer, and a separator, wherein the autothermal reformer divides methanol into two parts, one part is used for combustion to provide the heat required for reforming, and the other part is used for reforming to produce hydrogen, which is cracked and converted into a mixed gas of hydrogen and carbon oxides, and then the hydrogen and other gases are separated through the separator.

3. The marine methanol water reforming hydrogen production proton exchange membrane fuel cell system according to claim 2 is characterized in that: The purification condensation system includes a purifier and a condenser. The purifier is connected to the output end of the separator. The purifier is used to purify the gas output by the separator to remove impurities. The condenser is connected to the output end of the purifier. The condenser is used to remove moisture from the hydrogen. The condenser is also connected to the mixer. The condensed water output by the condenser flows back to the mixer and continues to mix with methanol to carry out the next step of the process.

4. The marine methanol water reforming hydrogen production proton exchange membrane fuel cell system according to claim 3 is characterized in that: The proton exchange membrane fuel cell comprises an oxygen input end and a hydrogen input end, wherein the hydrogen input end is connected to the outlet of the condenser, and the proton exchange membrane fuel cell is also connected to the output end of the purifier, and the cathode water outputted by the proton exchange membrane fuel cell is used as the supply of the purifier.

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