RU2291228C2 - Reactor for producing hydrogen and oxygen by plasmochemical and electrolysis processes - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: reactor includes high-pressure vessel and wave-guides of SHF irradiation generator. Vessel is in the form of cylinder whose ends are closed by means of spherical bottoms where wave-guides of SHF irradiation generator are arranged mutually in opposite. Between said wave-guides parallel hollow perforated electrodes are arranged at fixed intervals. Cavities of said electrodes are communicated with drying refrigerators and molecular sieves. Wave-guides are mounted in such a way that to direct SHF irradiation along intervals between electrodes. Irradiation frequency is selected in such a way that to create between electrode resonance standing wave. Reflectors in the form of semicircular screens are arranged between wave-guides and bottoms; nozzles for feeding carbon monoxide and steam are arranged between wave-guides and electrodes.

EFFECT: change of main mode of nuclear electric power stations to controlled mode due to producing hydrogen and oxygen for periods of reduced consumer's load and due to using hydrogen and oxygen in gas-steam apparatuses of additional electric power stations at periods of pick and pick-half loads of consumer's plants.

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Description

The invention relates to the field of energy and can be used to transfer nuclear power plants from a basic operating mode to a dispatch mode with the simultaneous production, use and accumulation of hydrogen and oxygen, during periods of decline in electricity consumption (night time, weekends and holidays), hydrogen and oxygen are generated and accumulated , and during periods of increasing electrical load consumption above the nominal in half-peak and peak modes, they are used in gas turbine generators of the combined cycle flax power station.

At present, it is economically feasible to replace natural hydrocarbon fuel with hydrogen fuel, both from the point of view of economics and from the point of view of environmental ecology. In addition to the above method of using hydrogen and oxygen, they can be used: in high-performance turbines equipped with mixing superheaters with high-pressure hydrogen-oxygen burners; in various types of fuel cells, reciprocating and gas turbine units of a transport type using solid-state hydrogen storage devices.

At present, various methods for producing hydrogen from fossil fuels in industry under the conditions of expensive equipment with a relatively small resource have been developed, the process requires preliminary purification of the feedstock and the resulting product, and in terms of emissions into the environment it corresponds to the burning of this fossil fuel.

The second semi-industrial semi-laboratory method for producing hydrogen and oxygen is the electrolysis method, but due to the low capacities of the plants and the relatively high energy consumption, it is more than 5-6 kWh per 1 cubic meter. m H _{2 is} not widely used in industry.

The third laboratory method is the method of producing hydrogen and oxygen by a plasma-chemical method based on the ionization of carbon dioxide in the field of microwave radiation, which is close to the vibration frequency of carbon dioxide molecules. As a result of microwave irradiation of carbon dioxide, energy equal to ~ 2.89 eV / mol is absorbed and carbon monoxide CO + 1 / 2O _{2 is formed} with partial ionization of the mixture, all intermediate reactions proceed in a nonequilibrium state and the reaction products must be constantly removed. In the presence of water vapor in carbon dioxide, carbon monoxide is formed, which reacts with water vapor: СО + Н ₂ О → СО ₂ + Н ₂ . This reaction is again nonequilibrium and a constant removal of decomposition products from the reaction zone is required.

The whole process takes place near the perforated surface of electrolysis electrodes of opposite polarity, and the electrodes themselves are hollow, connected to refrigeration dryers, with molecular sieves and with outlet coolers, and due to the perforation of the electrodes, they were able to avoid their polarization and further decompose water vapor into hydrogen and oxygen, with the conclusion of unstable decay products from the reaction zone and exposure to microwave radiation.

The described process is entirely determined by the magnitude of the reverse reaction course of the synthesis of carbon dioxide and water from the reaction components, in order to reduce the reverse reaction course, the following measures are carried out:

- maintaining in the volume of the reactor the pressure of carbon dioxide and water vapor in the range of 2.0-2.5 MPa, which is a good inhibitor; at the same time, microwave-treated carbon dioxide is a good catalyst for the decomposition of water vapor into hydrogen;

- simultaneously with the above processes in the reactor there is a constant purging of the volume from the decomposition products into the output system through the perforation of the electrodes, thereby eliminating the reverse reactions;

- additionally, free volumes are reduced in the reactor volume to a minimum in order to reduce the volumes of nonequilibrium gas components that can participate in reverse reactions.

An analogue and prototype of the processes and design of “Reactors for the production of hydrogen and oxygen by plasma-chemical and electrolysis methods” was a laboratory plant for the production of hydrogen and oxygen by the plasma-chemical method, developed in IAE im. IV Kurchatova, molecular sieves developed there [1].

However, a laboratory setup with small reactor volumes of ~ 50 cm cubic meters, with quartz diaphragms and large parasitic volumes and discrete processes cannot be used in industrial production, since:

- the installation capacity should be several hundred MW;

- volumes of several hundred cubic meters .;

- the cheapest electricity tariff should be used - the night one;

- the output of the reactor is tens of thousands of cubic meters. hydrogen and oxygen per hour;

- water vapor that is used in the reactor must be used in the turbogenerator, that is, from the turbine take-offs;

- carbon dioxide can be delivered as a waste product for refueling in a gaseous or solid state from refineries;

- safety conditions must correspond to the industrial production of hydrogen and oxygen;

- the use of quartz windows for waveguides in conditions of variable reactor operating conditions is very problematic, and they are replaced by metal diaphragms, based on a mesh base;

- and last, an industrial installation is continuously operating, and not periodically, like a laboratory, which can be stopped at any time.

The present invention, “A reactor for producing hydrogen and oxygen by the plasma-chemical and electrolysis method,” serves to transfer from a laboratory research method to the full-scale combined production of hydrogen and oxygen by plasma-chemical and electrolysis methods in industry. Contains: a cylindrical reactor pressure casing, sealed from two ends with spherical bottoms, in which waveguides from microwave radiation generators are oppositely mounted, between which hollow electrolysis electrodes with a perforated surface are installed, the cavities of which are connected to output devices: refrigerators - dehumidifiers, molecular sieves and output refrigerators, the pressure vessel of the reactor is shielded from microwave radiation by hemispherical screens, in the gaps between the screens and electrodes zerah mounted unit injector, the feed carbon dioxide and water vapor into the reactor core at the cell electrodes are perforated.

Microwave radiation is directed into the gaps of parallel and oppositely charged electrodes, which creates an electrically conductive plasma from a mixture of carbon dioxide and water vapor, which additionally decomposes water vapor on oppositely charged electrodes and separates hydrogen and oxygen each at its electrode, removing them from the decomposition zone in its own way. internal channels in the electrodes for molecular sieves, carbon dioxide and water are returned to the cycle. The main purpose of the reactor: the production of hydrogen and oxygen in the most economical way, with the possibility of transferring nuclear power plants from the base mode to the control room, without compromising the safe working conditions of the nuclear reactor and the nuclear power plant as a whole. This is achieved due to the fact that the station both worked in the basic mode and works: but during periods of unclaimed load, hydrogen and oxygen are generated in the plasma chemical and electrolysis reactor, in the future, the hydrogen and oxygen accumulated in the gas holders are used to generate additional energy, compensating for peak and half-peak loads at the consumer, with excessive accumulation of hydrogen and oxygen, it is possible to supply hydrogen to the gas line to replace the flow of natural gas - this is possible, since the parameter The fire safety and explosive safety standards for hydrogen and natural gas are the same, however, hydrogen is preferable in terms of environmental indicators, as water vapor is generated during the combustion of hydrogen.

At the same time, due to the difference in tariffs of night, half-peak and peak modes, it is possible to make a profit, so according to the Resolution of the FEC No. 11 of 04/02/2002: -

- night rate - 284 rubles / MW · hour;

- peak mode - 603 rubles / MW · hour.

The cost of electricity for 1 cubic meter m N ₂ not more than 4 kW · h. The amount of energy unclaimed by the consumer and replaced by the production of hydrogen and oxygen for a unit of 1000 MW at night is about 400 MW for 8 hours, in peak mode, it is necessary to additionally release the consumer in excess of the installed capacity of 400 MW for 2-3 hours. The above facts make it possible to use a nuclear reactor in stationary mode, a hydrogen-oxygen reactor to compensate for power consumption dips, and use hydrogen and oxygen to compensate for peak and half-peak modes in combined cycle plants.

The proof of the essential features of the invention “A reactor for producing hydrogen and oxygen by plasma-chemical and electrolysis methods” is a design consisting of the following elements: a cylindrical high-pressure vessel, closed from the ends by spherical offspring, in which the waveguides are mounted positively, the ends of the waveguides are closed by metal membranes, which are supported by mesh base on the side of the microwave generators, between the oppositely located waveguides installed electrolyzer electrodes with perforation ovannoy surface and a hollow inside, connected to the output devices: refrigerators, desiccants, molecular whitefish and output refrigerators. The electrolyser electrodes are parallel to each other at a distance of δ = 1.2-1.3 microwave wavelengths.

Between the microwave emitters and the bottoms of the pressure casing, screens are installed that protect the metal of the casing from microwave radiation and direct the diffused stream of radio emission to the electrodes. Between microwave emitters and electrolyser electrodes, nozzle blocks are installed that supply carbon dioxide and saturated steam to the reactor volume, mixing them in the microwave and electrolysis electrodes, on which further decomposition and separation of mixtures with hydrogen and oxygen takes place and decomposition products are removed through them separation and purification, after which hydrogen and oxygen are sent to their gas tanks, and carbon dioxide and water are returned to the cycle.

Perforation of the surface of the electrodes and removal of water vapor decomposition products through the hollow channels inside the electrodes allows their polarization to be avoided, which compensation required an additional at least 2 kWh per 1 cubic meter. m N ₂ . The essence of the invention is presented by drawings.

Figure 1. The basic design of the reactor for the production of hydrogen and oxygen by plasma-chemical and electrolysis methods.

Figure 2. Dependence of plasma conductivity on the degree of ionization of a mixture of water vapor and carbon dioxide.

Figure 3. The dependence of the energy restriction of the state of the molecules of a mixture of H ₂ O + CO ₂ , taking into account reverse and chain reactions.

Figure 4. The energy dependence of the production of hydrogen from a mixture of CO ₂ + H ₂ O on the ratio of CO ₂ / H ₂ O and the vibrational temperature of the molecules Tv.

Figure 5. The stability region during the production of hydrogen and oxygen with respect to reverse reactions depends on the ratio of СО ₂ / Н ₂ О of the energy of the mixture molecules.

Figure 1 presents the basic design of the reactor for the production of hydrogen and oxygen by plasma-chemical and electrolysis methods.

The reactor consists of a pressure vessel 1, spherical bottoms 2 and 3, hollow perforated electrolysis electrodes 4 and 5 parallel to each other located at a fixed distance “δ”, to which a low-voltage current of different polarity from a direct current source 6 is driven, generators 7 and 8 are super high-frequency ( Microwave oscillations are connected to the waveguides 9 and 10, which pass into the pressure housing 1 through the bottoms 2 and 3, the bottoms 2 and 3 themselves and the pressure housing 1 are protected from the microwave by hemispherical screens 11 and 12, which direct the scattered radiation from the waveguides 9 10 as well as from the support grids 15 and 16 and the metal diaphragms 13 and 14 to the side electrodes 4 and 5.

The internal cavity of the pressure housing 1 from the environment in the waveguides 9 and 10 is separated by metal diaphragms 13 and 14, resting inside the waveguides on supporting grids 15 and 16 (brittle materials like quartz are excluded).

In the internal cavity of the housing 1, volumes 19 and 20 are supplied through the nozzle blocks 17 and 18 with carbon dioxide by nozzles 17 from a gas holder and saturated water vapor by nozzles 18 from a steam generator turbine generator.

The products of partial decomposition of a mixture of carbon dioxide and water vapor are plasma and are fed into fixed gaps “δ” between bipolar electrodes 4 and 5, on which hydrogen and oxygen are separated, and products of carbon dioxide decomposition are discharged through perforation and channels in electrodes 4 and 5 and water vapor to the refrigerator-driers 21 and 22, the dried mixtures are fed to molecular sieves 23 hydrogen, 24 oxygen and 25 carbon dioxide, where the final purification of hydrogen, oxygen and carbon dioxide and from impurities and cooling in refrigerators: carbon dioxide 26, hydrogen 27 and oxygen 28, after which the obtained purified and cooled hydrogen and oxygen are sent to storage, and water and carbon dioxide are sent to the cycle, it should be noted that carbon dioxide is not consumed in the process decomposition of water into hydrogen and oxygen, with the exception of natural losses during transportation, transshipment and purging, a small part of carbon dioxide leaves with the produced oxygen, since molecular sieves for carbon dioxide 25 and oxygen 24 are not completely separated dissolved carbon dioxide and oxygen.

In figure 1, for clarity, the electrodes 4 and 5 of the electrolyzer are rotated 90 ° around the vertical axis, and microwave radiation is directed into the gaps "δ" between the electrodes until the formation of standing resonant waves. The small arrows show the movement of the plasma to the electrodes 4 and 5, into the perforation and decomposition products into the internal channels to the cleaning system and their removal from the system.

Figure 2 shows the dependence of the plasma conductivity on the degree of ionization of carbon dioxide and water vapor, and when irradiated with a mixture of H ₂ O + CO ₂ microwave carbon dioxide absorbs energy and decomposes into CO and 1 / 2O ₂ , in turn, CO decomposes water into N ₂ and CO ₂ , all reactions are not in equilibrium, this reaction proceeds without the expenditure of external energy, however, the energy of the mixture molecules cannot be more than 1500 K, since the reverse reactions increase, which can go into a chain reaction, see FIG. 3.

Figure 3 shows the limitations during the process from 300 K to 1500 K, and the vibrational temperature of the reactants Tv varies over a fairly wide range from 0.1 to 0.3 eV.

Figure 4 shows the dependence of the hydrogen yield on the ratio of CO ₂ / H ₂ O and vibrational temperature Tv. Moreover, the optimum yield of the final products is within the ratio of СО ₂ / Н ₂ О ~ 3-10 times and Tv ~ 0.2-0.3 eV, which is well controlled, with other values above the indicated values in the optimal mode, the ratio is about 6 and Tv = 0.25 eV seems to be a problem; research is needed.

Figure 5 shows the areas of process stability in the reactor with respect to reverse reactions.

Plasma-chemical analysis and synthesis in a mixture of CO ₂ -H ₂ O is a complex nonequilibrium physicochemical process, which, depending on the ionizing microwave radiation and the composition of the mixture, can lead to the formation of various products, we are interested in the reactions leading to the production of molecular hydrogen. To obtain molecular hydrogen, the degree of ionization in a mixture of CO ₂ —H ₂ O must be at least log (n _e / n _o ) ~ 1. Upon reaching the required degree of ionization in a mixture of carbon dioxide and water vapor, the reactions proceed according to the following scheme:

CO education:

СО₃, при этом колебательном возбуждении СО₂ Tv ~0,1 эВ, атомарный кислород быстрее вступает в реакцию (3), чем в трех (СО₃) частичную рекомбинацию. В этом случае основная доля атомов кислорода (или аналогично радикалов СО₃) вступает в реакцию с СО₂, однако часть из них реагирует с парами воды:CO ₂

CO ₃ , with this vibrational excitation of CO ₂ Tv ~ 0.1 eV, atomic oxygen reacts faster (3) than in three (CO ₃ ) partial recombinations. In this case, the main fraction of oxygen atoms (or similarly to CO ₃ radicals) reacts with CO ₂ , however, some of them react with water vapor:

O + H ₂ O → OH + OH; E _y ~ 1 eV / mol; the OH radical formed initiates the process of molecular hydrogen reduction from water using CO:

The range of parameters at which hydrogen generation occurs is limited by the reactions:

OH + H → H ₂ O + O;

H + CO ₂ → OH + CO;

H + O ₂ → OH + O; these reactions are limited by the parameters indicated in FIG. 3, the limits limiting the scope of the reaction mechanism (4) and (5) are also indicated there.

The hydrogen stability criterion in this case will be: the restriction on T _o necessary to prevent a chain reaction is described by competing reactions:

H + O ₂ → OH + O; E _about ~ 0.7 eV / mol; To _about = 10 E -10 cm ³ / s; H + O ₂ + M → M + HO; K ₃ ~ 3E-31 cm ³ / s; whence it can be seen that a safe reaction will take place provided:

T _about <E _o ln ^-1 [Ko / K ₃ n _o ].

The reactor for producing hydrogen and oxygen by plasma-chemical and electrolysis methods works as follows:

the reactor - 1 is blown with saturated water vapor through nozzles 18, at the same time electricity is supplied to a direct current and low voltage source 6 and electrodes 4 and 5 of the electrolyzer, power is supplied to microwave generators 7 and 8, which heat up and reach the required power and frequency on waveguides 9 and 10, after reaching the required parameters on the waveguides, carbon dioxide and water vapor are supplied through the nozzle blocks 17 and 18, carbon dioxide and water vapor enter the mixing and ionization volumes 19 and 20, partially ionized Zma from volumes 19 and 20 enters the gaps “δ” between the electrodes 4 and 5, where the mixture of carbon dioxide and water vapor is further ionized, hydrogen and oxygen are separated at the electrodes, water vapor is further decomposed into hydrogen and oxygen and the decomposition products are removed through perforation and channels inside the electrodes 4 and 5, to the drying coolers 21 and 22 and the molecular sieves 23, 24 and 25, in which the final separation of hydrogen, oxygen and carbon dioxide occurs, then the products after molecular sieves 23, 24 and 25 are fed to olodilniki: carbon dioxide 26 hydrogen 27 and oxygen 28, hydrogen and oxygen is directed to the storage, and the water and carbon dioxide are returned to the cycle. The resulting hydrogen and oxygen are ready for use in industry, domestic conditions and storage in gas tanks.

Feasibility study of the operation of the reactor to produce hydrogen and oxygen.

The reactor can be used with any source of electric power, but it is advisable to use the electric power of nuclear power plants during the period of low electricity consumption and with the use of hydrogen and oxygen in peak and semi-peak modes at start-up power plants using a combined cycle. In this case, the main equipment, for example, nuclear power plants with VVER-1000 reactors, constantly operates in the basic mode, and the production and use of hydrogen and oxygen removes dips and peaks and half peaks, in fact, a large-capacity nuclear power plant and the starting power station operate in supervisory mode by electrical load with increased effective efficiency.

It is possible to use the obtained hydrogen when substituting natural gas for consumers both in industry and in domestic conditions of use.

The estimated cost of the accumulated hydrogen and oxygen obtained in the reactor 1 can be determined from the conditions:

- the cost of electricity to obtain one cubic meter. m of hydrogen will be no more than 4 kWh;

- the differential tariff (according to the Decree of the FEC No. 11 of 04/02/2002) will be:

- nighttime 284 rubles / MW · hour;

- half-peak - 355 rubles / MW · hour:

- peak - 603 rubles / MW · hour;

assuming a night tariff of about 8 hours and having a capacity of about 400 MW;

the estimated peak tariff is approximately 2–3 hours with an estimated capacity of 400 MW to compensate for the peak.

Calorific value of hydrogen: higher, middle, lowest, kJ / cubic meter, respectively: 12778.1, 11769.1, 10760.1. It should be noted that the higher calorific value of hydrogen can be obtained by burning a hydrogen-oxygen mixture of stoichiometric composition in high-pressure burners. In our case, we consider the higher and average calorific values of hydrogen.

Calculation of the economic effect

The cost of unclaimed night energy, thousand rubles C = T × M × s = 8 × 400 × 284 = 908.8;

The volume of hydrogen obtained from unclaimed energy: V = Mnv × Tnoch /

m = 400 × 8/4 = 800 thousand cubic meters of N ₂ ;

Calorific value of hydrogen: kJ / m3 the highest average 12778.1 11769.1 Energy enclosed in 800 thousand cubic meters of H ₂ GJ 10222.48 9415.3 The network is given, MW 400 400 From the combined cycle with efficiency 0.6 0.6 Energy supplied to the network, MW · h 1703.7 1569.2 Peak load holding time, T hour = Eel / Mpik 4.26 3.92 The cost of electricity, with peak compensation
load, thousand rubles
1027.33
946.23 Profit excluding depreciation and wages for one cycle - “failure peak”, thousand rubles 118.53 37.43 Assuming only weekly and holiday load fluctuations K = 60 per year, we get, thousand rubles. 7111.8 2245.8

In addition, it is possible to use hydrogen when replacing fossil fuels - natural gas in industry and everyday life at current world gas prices and is guaranteed in the future. For example, at a cost of 1000 cubic meters of natural gas supplied to European consumers 230 $ / 1000 cubic meters, with a calorific value of natural gas of 33 MJ / cubic meter and ρ = 0.6-0.7 kg / cubic meter (gas Komi), for one cycle: failure rating.

Replaced gas volume, cubic m
Cost of replaced gas, thousand rubles 310000
1782000 285000
1640000

Thus, the use of a reactor for the production of hydrogen and oxygen by plasma-chemical and electrolysis methods allows the transfer of a nuclear power plant with VVER-1000 reactors and a start-up boiler with a steam-gas cycle from the base load mode to the control room and, in addition, make a profit by replacing natural gas with hydrogen.

Information sources

1. Atomic-hydrogen energy and technology. " Collection of articles, issue 8, pp. 100-115.

V.A. Legasov et al. “Plasma-chemical methods for producing energy carriers”.

Claims (1)

A reactor for producing hydrogen and oxygen by plasma-chemical and electrolysis methods, comprising a high-pressure housing and microwave generators waveguides, characterized in that the housing has the form of a cylinder closed at the ends with spherical bottoms, in which microwave generators are installed on opposite sides, between which are located on a fixed distance parallel parallel hollow perforated electrodes, the cavities of which are connected to refrigeration dryers and molecular In this case, the waveguides are installed so that the radiation is directed along the gaps between the electrodes, and the radiation frequency is selected in such a way as to create a resonant standing wave between the electrodes, reflectors in the form of hemispherical screens are installed between the waveguides and the bottoms, and installed between the waveguides and electrodes nozzles for supplying carbon dioxide and water vapor.

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