RU2761902C1 - Power plant based on a fuel cell, hydrocarbon to hydrocarbon converter and oxygen concentrator - Google Patents

Abstract

FIELD: fuel cells.

SUBSTANCE: invention relates to fuel cells, in particular to power generating units on fuel cells, intended for use as mobile (portable, mobile) and/or stationary units, including periodically operating in airless environments, for example, in marine underwater robotic systems. To achieve the effect, a power plant based on a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator is proposed, including a fuel cell, a hydrocarbon fuel converter, storage tanks for water, hydrogen and oxygen, connected by pipelines with electrovalves and throttles, while the power plant contains an oxygen concentrator, including an air compressor, columns with zeolite, solenoid valves and throttles, in which a mixture highly enriched with oxygen is produced, which is partially accumulated in the oxygen tank and is fed through the pipeline both to the inlet of the oxidation circuit of the fuel cell and to the inlet of the hydrocarbon fuel converter, which includes a high-temperature catalytic unit connected by a pipeline to a reservoir with hydrocarbon fuel, in which a gas mixture of carbon dioxide and hydrogen is formed, a heat exchanger in which it is cooled, and a reactor for steam reforming of carbon monoxide, connected by a pipeline with a tank with water, while the produced mixture of hydrogen and carbon dioxide flows through the pipeline into a membrane metal hydrogen separator, from which the produced hydrogen is supplied through the pipeline to both the hydrogen storage tank and the hydrogen inlet. the fuel cell circuit.

EFFECT: ensuring the operation of fuel cells and a hydrocarbon fuel converter using oxygen of a high degree of enrichment with a simplified design of the installation and an increase in its operation time in airless environments.

1 cl, 1 dwg

Description

Technology area

The invention relates to fuel cells, in particular, to power generating installations on fuel cells intended for use as mobile (portable, mobile) and / or stationary installations, including periodically operating in airless environments, for example, in marine underwater robotic systems.

State of the art

Fuel cell power plants and their constituent elements are widely known.

Known power plant based on fuel cells (patent RU 2526851), consisting of a hydrocarbon fuel converter, including a shift reactor, connected to a hydrogen outlet with a fuel cell that generates electricity.

Known power plant underwater vehicle (patent RU 2320056), including a fuel cell and storage tanks for hydrogen and oxygen.

Known autonomous power supply system (patent RU 2277273), consisting of a power plant, including a fuel cell and storage tanks for hydrogen and oxygen.

The known power plant of an underwater vehicle (patent RU 2284078), in which a magnesium mass dissolved in an electrolyte is used as a source of hydrogen.

Known device, method and system for obtaining thermal and / or kinetic, as well as electrical energy (patent RU 2414774), containing a power plant in which hydrocarbon fuel releases hydrogen in a special dehydrogenation reactor. The hydrogen is burned in the fuel cell, and the rest of the hydrocarbon fuel is burned in the internal combustion engine.

Known installation for the production of electricity from hydrocarbon raw materials (patent RU 2388118) and power plants on fuel cells (RU 2353023 and RU 2311544) containing a hydrocarbon fuel converter, including a reactor for steam reforming of carbon monoxide and a fuel cell of various types.

Known power plant with a fuel cell for the Arctic zone (patent for invention RU 2722751), containing a solid polymer fuel cell, a hydrogen source, a blower, a humidifier, pressure regulators, metering valves, characterized in that it contains a catalytic recombiner and a bubbler, the input of the catalytic recombiner is connected through metering valves with a blower and a hydrogen source, the outlet of the catalytic recombiner is connected to the inlet of the bubbler, and the outlet of the bubbler is connected through metering valves to the hydrogen and air inlets of the fuel cell.

Known power plant based on solid oxide fuel cells (RU 2702136), containing at least one solid oxide fuel cell with an anode and a cathode, a reformer, an anode gas recirculation and separation module, characterized in that it is equipped with an afterburner and two heat exchangers, and a recirculation and separation module of anode gases includes at least two heat exchangers, a water gas reactor, a separator, a pump, a condenser, a storage tank, a steam generator connected by a pipe system, while the outlet from the anode space of the SOFC is connected in series with the first and second heat exchangers, a water gas reactor, a separator, a pump, the second heat exchanger, the reformer, the first heat exchanger and the entrance to the anode space of the SOFC, in addition, the separator is connected to the condenser, which is connected by one direct pipeline for the gaseous product to the afterburner, another direct pipeline for water is connected in series with the storage tank, evaporator, tr A network heat exchanger and a pump and a return pipeline is connected to the fourth heat exchanger and the inlet to the cathode space, the afterburner is connected in series with the fourth and third heat exchangers, the steam generator, and the outlet from the cathode space is connected to the afterburner.

Power plants consisting of a fuel converter and a fuel cell are described in the literature (V.B. Avakov, D.A. Khayrov, I.K. for power plants on fuel cells ", Proceedings of the Krylov State Scientific Center. Vol. 2, No. 388. 2019).

The main disadvantage of these installations is that, without an oxygen concentrator at the outlet of the partial oxidation of hydrocarbons converter, the resulting gas fuel mixture, due to the presence of ballast nitrogen in it, contains a small amount of hydrogen (10-15%) and the same small amount of carbon monoxide. This fuel mixture with ballast nitrogen is difficult to modify in the reactor for additional oxidation of carbon dioxide, to isolate in the hydrogen separator unit and use it as a fuel in a fuel cell.

Individual elements of the proposed power plant based on a fuel cell are also widely known, for example, the oxygen concentrator unit has a typical design close to that described in patent RU 149979 and consists of two columns filled with zeolite for the implementation of the short-cycle nitrogen absorption process and electrovalves for alternately filling the columns with air and venting the removed nitrogen, the hydrocarbon fuel conversion unit was previously described in patents RU 2624708 and RU 2085476, the fuel cell unit is described in patents RU 2345447 and RU 68780.

The technical problem to be solved by the claimed invention is to increase the productivity and efficiency of the fuel cell and the hydrocarbon fuel converter as part of the power plant, as well as to increase the autonomous operation of the unit in airless environments.

Disclosure of the essence of the invention

The technical result is to ensure the possibility of operation of fuel cells and a hydrocarbon fuel converter on oxygen of a high degree of enrichment, which leads to a simplified design of the installation and an increase in its operation time in airless environments.

To achieve the technical result, a power plant based on a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator is proposed, including a fuel cell, a hydrocarbon fuel converter, tanks for storing water, hydrogen and oxygen, connected by pipelines with electrovalves and throttles, while the power plant contains a concentrator oxygen, including an air compressor, columns with zeolite, solenoid valves and throttles, in which a mixture highly enriched with oxygen is produced, which is partially accumulated in the oxygen tank and is fed through a pipeline both to the input of the oxidation circuit of the fuel cell and to the input of a hydrocarbon fuel converter, including a high-temperature a catalytic unit connected by a pipeline to a tank with a hydrocarbon fuel, in which a gas mixture of carbon dioxide and hydrogen is formed, a heat exchanger in which it is cooled and a steam reforming reactor for carbon monoxide Water connected by a pipeline to a tank with water, while the produced mixture of hydrogen and carbon dioxide flows through the pipeline into a membrane metal hydrogen separator, from which the produced hydrogen is supplied through the pipeline both to the hydrogen storage tank and to the inlet of the hydrogen circuit of the fuel cell.

Brief Description of Drawings

The figure shows a diagram of a power plant based on a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator, where:

1 - air compressor;

2 - columns with NaX zeolite;

3 - electrovalves;

4 - chokes;

5 - capacity of compressed oxygen;

6 - container with hydrocarbon fuel;

7 - block of high-temperature catalyst for the reaction of partial (partial) oxidation of hydrocarbon fuel;

8 - tubular heat exchanger;

9 - reactor for steam reforming of carbon monoxide;

10 - a container with water;

11 - membrane metal hydrogen separator;

12 - buffer tank with hydrogen;

13 - fuel cell;

14 - oxygen concentrator;

15 - hydrocarbon fuel converter;

16 - pipelines (the arrow shows the direction of movement).

Implementation of the invention

The claimed technical solution consists in using a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator as part of one power plant. The hydrocarbon fuel converter works on the principle of partial (partial) oxidation of hydrocarbons. In this case, both the fuel cell and the fuel converter use the oxygen obtained in the oxygen concentrator as an oxidizer, which leads to an increase in the productivity of the fuel cell and the fuel converter, and also significantly simplifies the design of the hydrocarbon fuel converter, since there is no ballast nitrogen in the produced hydrogen-containing gas, the share of which is significant when using oxygen in the air. In addition, the use of almost pure oxygen (95%) makes it possible to store a larger amount of oxidizer in buffer, accumulating tanks, which makes it possible to operate the unit for a long time in airless environments, for example, in marine robotic complexes.

The inventive power plant based on a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator, shown in the figure, contains an oxygen concentrator 14, including an air compressor 1 supplying air to the columns with zeolite 2, electrovalves 3 and a choke 4. The highly oxygen-enriched mixture generated through pipeline 16 from an oxygen concentrator 14 with a pressure of 3 atm. when supplied to a hydrocarbon fuel converter 15, which includes a high-temperature catalytic unit 7, a heat exchanger 8, a carbon monoxide steam reforming reactor 9 and a container with water 10. Hydrocarbon enters the catalytic tank 7 through a pipeline 16 from a container with hydrocarbon fuel 6 or a liquefied gas tank (propane butane mixture). The mixture of hydrogen and carbon dioxide flows through the pipeline 16 into the membrane metal separator of hydrogen 11 and then through the pipeline 16 into the fuel cell 13.

The oxygen concentrator 14 has a typical design and consists of two columns 2 filled with NaX zeolite for the implementation of the short-cycle nitrogen absorption process. In addition to columns 2, oxygen concentrator 14 contains solenoid valves 3 and throttles 4 for venting nitrogen into the atmosphere and supplying oxygen both to the fuel cell 13 and to the hydrocarbon fuel converter 15. The inlet air pressure is 3 atm. Oxygen outlet pressure 3 atm. The outlet oxygen has a composition of 95% oxygen and 5% argon.

High-temperature catalytic unit for partial (partial) oxidation of hydrocarbons 7 is a thermally insulated volume filled with heated to 700-1500 ° C with a catalyst representing a layer of ceramic granules coated with metal. Possible work without coating, only on ceramic granules. To prevent heat loss, the high-temperature catalyst layer is thermally insulated outside with a high-temperature fibrous ceramic mullite-silica thermal insulation or a material of the “fibrous alumina” type. In the high-temperature catalytic unit for the partial (partial) oxidation of hydrocarbons 7, the partial oxidation of the hydrocarbon with oxygen takes place according to the reaction C _n H _m + n / 2O ₂ = nCO + m / 2H ₂ . It is also possible to carry out in block 7 joint steam-oxygen conversion with reactions C _n H _m + n / 2O ₂ = nCO + m / 2H ₂ . and C _n H _m + nH ₂ O = nCO + (m / 2 + n) H ₂ . At the outlet, a mixture of CO and H ₂ heated to the catalyst temperature is obtained. In addition, it is possible to supply a small amount of water from the vessel 10 to the carbon monoxide steam reforming reactor 9 to generate additional hydrogen and to limit the process temperature.

A small tubular heat exchanger 8 or a pipe-in-pipe heat exchanger with air or water cooling is installed behind the high-temperature catalytic unit for partial (partial) oxidation of hydrocarbons 7 to reduce the temperature from the outlet temperature of the gas mixture at the high-temperature reactor to a gas temperature of 300-500 ° C at the inlet into the reactor for steam reforming of carbon monoxide 9, which is necessary for its efficient operation.

Reactor steam reforming carbon monoxide (or reactor "shift") 9 is a catalytic unit filled with a catalyst active particles of metals Cu, Cr, Fe, Zn and their oxides. In it, the reaction of oxidation of carbon monoxide with water takes place with the formation of additional hydrogen to CO + H ₂ O = CO ₂ + H ₂ . It can have one stage, with a temperature of 300-400 ° C, or it can have two stages, with different temperatures and catalysts. At the outlet of the reactor 9, a mixture of gases (H ₂ , CO ₂ , CO, Ar) with a high hydrogen content (60-70% vol.) Is obtained.

The membrane metal separator of hydrogen 11 is designed to separate pure hydrogen from the gas mixture leaving the steam reforming reactor 9 of carbon monoxide. It contains a thin palladium or vanadium membrane that selectively permits hydrogen through it. The structure of the membrane metal hydrogen separator 11 can be tubular or planar. The residual gas, after hydrogen evolves from it, is vented into the atmosphere by means of the solenoid valve 3.

The fuel cell 13 can be of the solid polymer, alkaline or phosphate type. In a preferred embodiment, the fuel cells in the battery contain a solid polymer electrolyte (membrane) or phosphate electrolyte.

The fuel cell 13 operates on hydrogen supplied from the membrane metal separator 11 and oxygen supplied from the oxygen concentrator 14. The hydrogen pressure is 2-3 atm. Oxygen pressure 3 atm. Outlets of both hydrogen and oxygen gas circuits of the fuel cell 13 are equipped with solenoid valves 3 for periodically bleeding off the impurities Ar accumulated in the fuel cell for the oxygen circuit and CO ₂ , Ar for the hydrogen circuit.

A power plant based on a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator operates as follows.

Compressor 1 pumps air into zeolite columns 2, where nitrogen is separated from the air by means of short-cycle absorption. As a result, the resulting mixture of 95% O ₂ and 5% Ar leaves the oxygen concentrator 14 through a separate pipeline 16. This highly oxygenated mixture is accumulated in the compressed oxygen tank 5 and then through the pipeline 16 is fed both to the inlet of the high-temperature reactor for partial oxidation of hydrocarbons 7 and to the inlet of the oxidation circuit of the fuel cell 13.

In the high-temperature unit for partial (partial) oxidation of hydrocarbon 7, a catalytic reaction between oxygen and hydrocarbon C _n H _m + n / 2O2 = nCO + m / 2H ₂ takes place, possibly together with an additional reaction of steam reforming of hydrocarbon C _n H _m + nH ₂ O = nCO + (m / 2 + n) H ₂ , resulting in the formation of a gas mixture of CO ₂ H ₂ . Hydrocarbon (methane, propane-butane mixture or liquid motor fuel) is supplied to this unit from tank 6. The temperature of the process in the catalytic unit is 700-1500 ° C.

Further, the gas mixture of H ₂ and CO from the outlet of the high-temperature unit for the partial oxidation of hydrocarbons 7 enters a small heat exchanger 8 where it is cooled to 300-500 ° C and then through pipeline 16 it enters the inlet of the carbon monoxide steam reforming reactor 9, where the oxidation reaction of monoxide takes place carbon with water to form additional hydrogen to carbon dioxide by the reaction: CO + H ₂ O = CO ₂ + H ₂ . Water is supplied to the reactor for steam reforming of carbon monoxide 9 from tank 10.

Further, a mixture of CO ₂ and H ₂ gases, including residues of CO and Ar with a high hydrogen content (60-70% vol.), Under a pressure of 3 atm enters the membrane metal separator of hydrogen 11 through pipeline 16, where hydrogen is released from the gas mixture, which through the pipeline 16 as fuel is supplied to the hydrogen circuit of the fuel cell 13.

As an oxidizer, a highly oxygen-enriched mixture from an oxygen concentrator 14 and a compressed oxygen tank 5 is supplied to the oxygen loop of the fuel cell 13 through the pipeline 16.

The operation of the power plant is controlled by a microprocessor system that controls solenoid valves 3 and other actuators, fuel and water pumps, and peripheral devices of the fuel cell (not shown in the figure).

The presence of a compressed oxygen capacity 5 of the required volume makes it possible to periodically use the installation in an airless environment, for example, in marine robotic complexes.

All parts of the installation are mounted on a common frame (shown in the figure) and are connected by 16 stainless steel pipelines.

The inventive power plant is characterized by a high content of hydrogen and carbon monoxide at the outlet of the catalytic unit for the conversion of hydrocarbon fuel 15, which makes it easier to oxidize in the reactor after oxidation of carbon monoxide and to release hydrogen in the separator unit 11, which greatly simplifies the installation.

In addition, the use in the fuel cell 13 is compressed to 3 atm. oxygen released by the oxygen concentrator 14 doubles its productivity.

In addition, the use of oxygen obtained in the oxygen concentrator 14 makes it possible to store it in the oxygen tank 5 and periodically use the power plant in an airless environment, for example, in a robotic complex.

Due to the use of the oxygen concentrator 14, the hydrocarbon fuel converter 15 operates on oxygen, which dramatically increases its efficiency. The hydrogen content at its outlet increases from 15% when the converter is operating in air, to 70% when operating on oxygen. Also, the performance (generation) of the fuel cell 13 increases up to 2 times. In addition, due to the use of the oxygen reserve instead of air, this power plant, with the same volume of oxidizer tanks, can take a much longer time (it increases 5 times compared to air) work in an airless environment, for example, in underwater robotic systems.

Thus, the combination of the above essential features leads to the following:

- the performance of the battery of the fuel cell 13 and the converter of hydrocarbon fuel 15 is increased, which leads to a decrease in the mass and size characteristics of the power plant and an increase in its specific productivity;

- the use of atmospheric oxygen increases the proportion of hydrogen in the gas generated by the hydrocarbon fuel converter 15, which simplifies its preparation for use in the fuel cell 13 and leads to a significant simplification of the entire generating unit;

- the operating time of the installation increases in an airless environment, for example, in marine robotic complexes.

The main advantages of the proposed solution.

1. In the hydrocarbon fuel converter 15, a mixture of oxygen (95%) and argon (5%) is used as an oxidizer instead of air (in traditional solutions), which leads to the absence of ballast nitrogen in the hydrocarbon fuel conversion products and, accordingly, in the hydrogen-containing working gas other items. This improves the operation of the high-temperature catalyst unit for the partial (partial) oxidation of hydrocarbon fuel 7, the "shift" reactor 9, increases the performance of the fuel cell 13 and the membrane metal hydrogen separator 11, and also simplifies the entire system.

2. The absence of ballast nitrogen in the oxidizer leads to a significant increase in the temperature of the hydrocarbon fuel conversion process (by a factor of 2 or more), which leads to an improvement in the operating parameters of the high-temperature catalyst unit for the partial (partial) oxidation of hydrocarbon fuel 7, namely, reduces its dimensions, increases the degree of conversion, makes it possible to use a cheap catalyst, prevents its seeding.

3. The use of oxygen, instead of air, increases by 5 times the amount of oxidant stored in the "wearable" storage tanks 5 of the system on board (in the form of compressed gas), which makes it possible to periodically work longer in an airless environment, which is relevant for marine robotic systems. The same applies to the stored amount of hydrogen in tank 12, which, in the absence of ballast nitrogen, stores a larger amount of hydrogen (approximately 3 times).

Claims (1)

A power plant based on a fuel cell, a hydrocarbon-to-hydrogen converter and an oxygen concentrator, including a fuel cell, a hydrocarbon fuel converter, storage tanks for water, hydrogen and oxygen, connected by pipelines with solenoid valves and chokes, characterized in that the power plant contains an oxygen concentrator, including air compressor, columns with zeolite, solenoid valves and throttles, in which a mixture highly enriched with oxygen is produced, which is partially accumulated in the oxygen tank and is supplied through the pipeline both to the inlet of the oxidation circuit of the fuel cell and to the inlet of the hydrocarbon fuel converter, including a high-temperature catalytic unit, connected a pipeline with a tank with hydrocarbon fuel, in which a gas mixture of carbon dioxide and hydrogen is formed, a heat exchanger in which it is cooled, and a carbon monoxide steam reforming reactor connected by a pipeline to a tank with water, while the produced mixture of hydrogen and carbon dioxide flows through the pipeline into the membrane metal hydrogen separator, from which the produced hydrogen is supplied through the pipeline both to the hydrogen storage tank and to the inlet of the hydrogen circuit of the fuel cell.

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