WO2012141621A1

WO2012141621A1 - Method for producing hydrogen

Info

Publication number: WO2012141621A1
Application number: PCT/RU2012/000332
Authority: WO
Inventors: Андрей Владимирович БАЛАСАНОВ
Original assignee: Balasanov Andrei Vladimirovich
Priority date: 2011-03-28
Filing date: 2012-04-26
Publication date: 2012-10-18
Also published as: RU2011111356A

Abstract

The invention relates to the production of practically pure hydrogen from a raw material containing carbon and hydrogen, without an operation involving separation of the gas mixture. In addition a second gaseous stream containing carbon monoxide (СО) is obtained at the same time as the hydrogen is obtained. The aforementioned technical result is achieved in that the reaction medium of liquid metal at a temperature above 1200°С consists of two zones connected to one another: a dissociation zone and a carbon oxidation zone, the gas space above these zones is separate, the raw material containing carbon and hydrogen is fed to the reaction mixture in the dissociation zone, an oxidizing agent is fed to the reaction medium in the carbon oxidation zone, gaseous reaction products are removed separately from the dissociation zone and the carbon oxidation zone, the carbon content in the reaction mixture is maintained above 0.5 wt.%, and the liquid metal of the reaction medium has less affinity for oxygen than carbon does.

Description

Method for the production of hydrogen.

The invention relates to methods for the production of hydrogen, and in particular to methods for producing hydrogen from raw materials containing carbon and hydrogen and can be used in metallurgy, energy, chemical industry, for the production of automotive hydrogen fuel.

Raw materials containing carbon and hydrogen are understood as oil and products of its processing, natural and associated gas, coal, shale, and other materials containing carbon and hydrogen.

A known method for the production of hydrogen, including the supply of raw materials containing carbon and hydrogen and an oxidizing agent to the catalyst, the removal of reaction products (RU 2 201 392, C01B 3/38).

The specified method requires a catalyst, which complicates and increases the cost of hydrogen production.

The closest in technical essence and the achieved result is a method for the production of hydrogen from raw materials containing carbon and hydrogen, including the formation of a reaction medium from a liquid metal with a temperature above 1200 ° C, with a gas space above its surface, supplying a raw material containing carbon to the reaction medium and hydrogen and an oxidizing agent (RU N ° 2 322 385, С01В 3/32).

This method provides a high degree of conversion of raw materials containing carbon and hydrogen to hydrogen without the use of a catalyst.

The disadvantage of this method is that hydrogen is produced in a mixture with other gases, the main of which are CO, C0 ₂ and H ₂ 0. For further use of hydrogen, it is necessary to separate it from these gases.

An object of the invention is to obtain substantially pure hydrogen without the operation of separating the gas mixture. Under almost pure hydrogen is meant a gas containing at least 90% H ₂ by weight.

An additional object of the invention is the simultaneous production of hydrogen to obtain a second gas stream containing carbon monoxide (CO).

This problem is solved by the fact that in the known method for the production of hydrogen from raw materials containing carbon and hydrogen, including the formation of a reaction medium from a liquid metal with a temperature above 1200 ° C, with a gas space above its surface, supplying a raw material containing carbon and hydrogen to the reaction medium and an oxidizing agent, according to the invention, the reaction medium consists of two interconnected zones: zones of dissociation of raw materials containing carbon and hydrogen and zones of carbon oxidation, gas space above these zones deleno, supplying a feedstock containing carbon and hydrogen to the reaction medium is carried out in the dissociation zone, the oxidant is supplied to the reaction medium in the carbon oxidation zone, the gaseous reaction products are removed separately from the dissociation zone and the carbon oxidation zone, the carbon content in the reaction medium is higher than 0.5% by mass, the liquid metal of the reaction medium has a lower affinity for oxygen than carbon.

As an oxidizing agent, air, oxygen, water vapor or drop moisture, carbon dioxide can be used. All these types of oxidizing agent can be used both separately from each other, and together in various combinations.

As the liquid metal, any metal with a lower affinity for oxygen than carbon can be used, in which the solubility of carbon at a temperature above 1200 ° C is more than 0.5% by weight.

As raw materials containing carbon and hydrogen, any materials with different ratios of hydrogen and carbon can be used. Other elements may be contained in the feed.

The process is as follows.

A reaction medium is formed from liquid metal, for example, by melting it or by pouring a preliminary molten metal. In one part of the reaction medium, which is the dissociation zone, feed materials containing carbon and hydrogen are fed. In another, which is a zone of carbon oxidation, an oxidizing agent is supplied.

Raw materials containing carbon and hydrogen can be supplied in various states, in gaseous, liquid, pasty or solid form. The feed can be carried out in various combinations through the upper, lower or lateral surface of the reaction medium in the dissociation zone.

The oxidizing agent can be supplied in various combinations through the upper, lower or lateral surface of the reaction medium in the zone of carbon oxidation.

And raw materials containing carbon and hydrogen and an oxidizing agent can be fed into the reaction medium as a single stream or dispersed in the corresponding zones.

When raw materials containing carbon and hydrogen are fed into the reaction medium, they are thermally decomposed: C _m H _n - mC + n / 2H ₂ .

The resulting hydrogen is removed from the reaction medium into the gas space in the dissociation zone.

Carbon dissolves in liquid metal.

The oxidizing agent is fed into the reaction medium in the zone of carbon oxidation. If the oxidizing agent is, for example, oxygen, then the reaction proceeds in the oxidation zone: 2C + 0 ₂ = 2 CO.

The resulting carbon monoxide (CO) is removed from the reaction medium into the gas space above the oxidation zone. That is, in the dissociation zone, carbonization of the liquid metal with carbon occurs during the thermal dissociation of raw materials containing carbon and hydrogen, and in the oxidation zone, this carbon is oxidized.

The zones of the reaction medium are interconnected, carbon is transferred from the dissociation zone to the oxidation zone in the reaction medium due to diffusion, due to mixing, for example, with raw materials containing carbon and hydrogen, an oxidizing agent, and gaseous reaction products.

The separation of the gas space above the zones of oxidation and dissociation provides two non-miscible streams of gaseous reaction products: a stream of hydrogen and a stream formed during the interaction of the oxidizing agent with carbon, which are removed separately from each other. Moreover, the separation of the gas space can be complete when not only the gas space is separated, but also partially the zones of carbon dissociation and oxidation, and partially when only the partial gas space is separated. It is important that the pelvic fluxes from the zones of dissociation and oxidation of carbon are not mixed.

The process is only possible if the carbon content in the reaction medium is higher than 0.5% by weight. That is, for example, iron can be used as a reaction medium, but copper, for example, cannot be used, since carbon dissolves in iron, but practically none in copper. With a lower carbon content in the reaction medium, it is not possible to efficiently transfer the raw materials formed by thermal decomposition containing carbon and hydrogen carbon from the dissociation zone to the oxidation zone. In addition, at temperatures above 1200 ° C with a carbon content in the reaction medium below 0.5% by weight, the oxidizing agent will oxidize the metal of the reaction medium, which will lead to the consumption of metal and, ultimately, to the impossibility of the process. The same will happen if the metal has a greater affinity for oxygen than carbon. That is, for example, iron can be used as a reaction medium, but aluminum, magnesium, calcium, for example, cannot be used, since iron at process temperatures has a lower affinity for oxygen than carbon, and aluminum, magnesium, and calcium are larger.

If the carbon content is reduced, increase the supply of raw materials containing carbon and hydrogen and / or reduce the supply of oxidizing agent. With an increase in carbon content, the supply of raw materials containing carbon and hydrogen is reduced and / or the supply of oxidizing agent is increased.

The temperature of the liquid metal should be above 1200 ° C. If the temperature is lower, the degree of dissociation of raw materials containing carbon and hydrogen will decrease, which will reduce the amount of hydrogen produced.

By reducing the temperature of the reaction medium, it is possible to increase the supply of raw materials containing carbon and hydrogen and an oxidizing agent. You can also use heat from an external source. With increasing temperature, the opposite can be done.

The dimensions of the dissociation and oxidation zones depend on a number of parameters: temperature, feed rate and depth, method and place of introduction of raw materials containing carbon and hydrogen and / or an oxidizing agent into the reaction medium, geometry of the reaction space and other parameters. The intensity of the oxidizing agent supply to the reaction medium can be several m ³ per 1 ton of metal in the oxidation zone per minute, for example 1 or 5. When implementing the process, it is important to ensure that the gaseous reaction products of the dissociation zone and the oxidation zone exit separately into the gas space above the reaction medium from friend. This can be achieved by calculating the geometric dimensions of the reaction medium, using known calculation methods, or by determining them experimentally.

Examples of process implementation schemes are shown in FIG. 1 and FIG. 2. Other options are possible. Notation Used:

1 - zone of dissociation, 2 - zone of carbon oxidation (1 and 2 are connected to each other),

3 - gas space above the dissociation zone, 4 - gas space above the carbon oxidation zone (3 and 4 are separated from each other).

Sometimes, to intensify the process, it is advisable to further circulate the reaction medium in a substantially horizontal direction. This contributes to a more efficient transfer of carbon from the dissociation zone to the oxidation zone, equalization of temperature in these zones. Such circulation can be carried out by electromagnetic stirring of the reaction medium, by mechanical or pneumatic stirring. It is also possible to periodically change the pressure over one or both zones to transfer liquid metal from one zone to another and vice versa. It is also possible to feed a feed containing carbon and hydrogen and / or an oxidizing agent by misaligned jets through the side surface of the reaction medium so that it circulates in a substantially horizontal direction.

It is most technically simple to maintain a pressure close to atmospheric in the gas space above the reaction medium.

It is sometimes useful to maintain a pressure above atmospheric in the gas space above the reaction medium. This makes it possible, for example, to transport gas reaction flows through pipelines without additional compression.

It is also useful to maintain various pressures in the gas space above the reaction medium above the dissociation zone and the carbon oxidation zone. This is useful in the case, for example, when hydrogen is transported through pipelines, and the gaseous reaction product from the oxidation zone is used immediately, for example, it is burned to produce heat.

The carbon content in the liquid metal of the reaction medium should be higher than 0.5% by weight at temperatures above 1200 ° C. There are a lot of such metals, but the most simple and cheap is to use an alloy consisting mainly of iron as a reaction medium.

If the feedstock containing carbon and hydrogen and / or the oxidizing agent is preheated, it is easier to maintain the temperature of the reaction medium. It is advisable that the feedstock containing carbon and hydrogen and / or the oxidizing agent be preheated with the heat of the gaseous reaction products.

It is sometimes desirable to add carbon to the reaction medium. This allows you to maintain the required concentration of carbon in the reaction medium if necessary. Also, by additionally supplying carbon, the formation of gaseous reaction products from the oxidation zone can be increased. In addition, the additional supply of carbon can increase the temperature of the reaction medium.

The amount of oxidizing agent supplied to the reaction medium is substantially sufficient to oxidize the carbon supplied to it to carbon monoxide (CO). This refers to carbon formed during the dissociation of raw materials containing carbon and hydrogen and (if supplied) additionally supplied carbon. A sufficient amount of oxidizing agent for this does not imply strict equality at every moment of time, but on the whole, such a ratio should be maintained. This will ensure the maintenance of carbon in the reaction medium at a level that allows the implementation of the process. If the amount of oxidizing agent is less, then the metal of the reaction medium will be saturated with carbon above the limit of its solubility in the metal, carbon will accumulate in the reaction medium in the form of solid carbon, partially removed with gaseous reaction products, which will reduce their quality. Otherwise, the carbon content will decrease and, ultimately, will become lower than 0.5% by mass, which will make the process impossible.

In some cases, a liquid metal reaction medium needs to be periodically updated. Updating can be carried out both by replacing part of the reaction medium, and by completely replacing it. This may be necessary if the feedstock containing carbon and hydrogen contains sulfur, and the production of gaseous reaction products with a low sulfur content is required. Once together with the raw materials containing carbon and hydrogen in the reaction medium, sulfur dissolves in the metal. However, gaseous reaction products contain less sulfur. Gradually, the sulfur concentration in the metal will increase and there will be no effect of reducing the sulfur content in gaseous reaction products due to the dissolution of sulfur in the metal. In this case, part or all of the reaction medium is renewed by draining the used metal and adding a sulfur-free metal. The molten metal may be subjected to sulfur removal by any known method and then reused.

Using this technique, together with the main objective of the invention, it is possible to solve the following: to purify sulfur from gaseous reaction products.

In the case when it is necessary to ensure high productivity of the method, it is possible to have several dissociation zones and / or several carbon oxidation zones in the reaction medium.

Sometimes it is useful to gaseous reaction products from the dissociation zone and / or from the carbon oxidation zone to partially burn in the gas space above the reaction Wednesday. This allows you to maintain the temperature of the reaction medium at the desired level without the use of additional heat sources.

It is possible to partially burn gaseous reaction products from the dissociation zone and / or from the carbon oxidation zone to heat the reaction medium from the outside, for example, in radiation tubes.

Example.

The reaction medium is formed from an alloy containing 97% iron and 3% carbon (hereinafter, percent by weight is meant). The temperature of the reaction medium is 1450 ° C. The dissociation zone of the reaction medium has dimensions (length / width / height) of 1000/1000/1000 mm. The carbon oxidation zone of the reaction medium has dimensions (length / width / height) of 500/1000/1000 mm. These zones are interconnected. Above the reaction medium, the gas space is divided above these zones by a partition from refractories, which is buried 100 mm into the reaction medium. In the gas space above both zones pressure is maintained close to atmospheric. Raw materials containing carbon and hydrogen (natural gas) are fed through the side surface of the dissociation zone below the surface of the reaction medium by 700 mm in an amount of 500 m ³ / hour (hereinafter, the volume of gases is given for normal conditions) by jet. An oxidizing agent (oxygen) is fed into the reaction medium in the zone of carbon oxidation through the lower surface in an amount of 250 m ³ / h. As a result of thermal decomposition of raw materials containing carbon and hydrogen, about 1000 m ³ / h of hydrogen is formed in the dissociation zone. Carbon in an amount of about 268 kilograms is dissolved in the reaction medium. Due to the action of the jet of raw materials containing carbon and hydrogen on the reaction medium, it is mixed, including in the horizontal direction, and dissolved carbon is delivered to the carbon oxidation zone. As a result of the interaction of dissolved carbon with an oxidizing agent, about 500 m ³ / h of carbon monoxide (CO) is formed in the oxidation zone. At such costs of raw materials containing carbon and hydrogen and an oxidizing agent, the concentration of carbon in the reaction medium is maintained at a level of 3%. The resulting hydrogen at a temperature of 1450 ° C in a heat exchanger heats the feed containing carbon and hydrogen before being fed into the reaction medium to 1100 ° C. Cooled hydrogen is compressed and transferred to storage tanks, from which the refueling of vehicles is carried out. Carbon monoxide is partially directed into radiation pipes located in the gas space above the reaction medium, where it is burned, ensuring the temperature of the reaction medium is maintained. The remaining carbon monoxide is sent to a gas cooler (boiler), then to a gas turbine to produce electricity, the combustion products are cooled together with the gaseous products after the radiation pipes. The heat generated during cooling of carbon monoxide and its combustion products is used to produce steam in the boiler. Carbon dioxide after the boiler is captured and partially sent to produce solid carbon dioxide (dry ice), partially pumped into underground storage. This process scheme provides zero emissions of carbon dioxide into the atmosphere when using raw materials containing carbon and hydrogen. Example 2

The reaction medium is formed from an alloy containing 98% cobalt and 2% carbon. The temperature of the reaction medium is 1550 ° C. The dissociation zone of the reaction medium has dimensions (length / width / height) of 30/20/50 mm. The zone of carbon oxidation of the reaction medium has dimensions (length / width / height) 40/20/50 mm. These zones are interconnected. Above the reaction medium, the gas space is divided above these zones by a partition of refractories. In the gas space above the dissociation zone and the oxidation zone, an increased pressure of 2 atm is maintained. Raw materials containing carbon and hydrogen (fuel oil) are fed through the lower surface of the dissociation zone in an amount of 300 grams / hour. The carbon content in fuel oil is 85%, hydrogen - 15%. Additionally, carbon (graphite) is supplied to the reaction medium in an amount of 300 grams / hour. An oxidizing agent (carbon dioxide - C0 ₂ ) is fed into the reaction medium in the zone of carbon oxidation through the upper surface in an amount of 1035 liters / hour. As a result of thermal decomposition of raw materials containing carbon and hydrogen in the dissociation zone, about 500 liters / hour of hydrogen are formed. Carbon in an amount of about 555 grams is dissolved in the reaction medium. Electromagnetic stirring of the reaction medium is carried out, including in the horizontal direction, and dissolved carbon is delivered to the carbon oxidation zone. As a result of the interaction of dissolved carbon with an oxidizing agent, about 1035 liters / hour of carbon monoxide (CO) is formed in the oxidation zone. The gas flows from the dissociation zones and the oxidation zone do not mix and are diverted separately from each other. At such costs of raw materials containing carbon and hydrogen and an oxidizing agent, the concentration of carbon in the reaction medium is maintained at a level of 2%. The resulting hydrogen with a temperature of 1550 ° C in a heat exchanger heats the oxidizer before it is fed into the reaction medium to 1000 ° C. Chilled hydrogen is transferred to storage tanks. Carbon monoxide from the oxidation zone is partially burned with oxygen in the gas space above the reaction medium above the oxidation zone. Partial carbon monoxide afterburning products in a heat exchanger heat the raw materials containing carbon and hydrogen to 400 ° C and then are sent as fuel to the burners. If it is necessary to obtain pure carbon monoxide together with hydrogen, it is not burned above the reaction medium, and the temperature of the reaction medium is maintained from an external source of electric heating.

Example 3

The reaction medium is formed from an alloy containing 96% iron and 4% carbon. The temperature of the reaction medium is 1500 ° C. The dissociation zone of the reaction medium has dimensions (length / width / height) of 500/300/800 mm. There are two zones of carbon oxidation of the reaction medium, located on both sides of the dissociation zone. Each of the oxidation zones has dimensions (length / width height) 200/300/700 mm. The dissociation zone and the carbon oxidation zone are interconnected. Above the reaction medium, the gas space is divided above these zones by a partition of refractories. In the gas space above the dissociation zone and oxidation zones is supported pressure close to atmospheric. Raw materials containing carbon and hydrogen (natural gas) are fed through the lower upper zone of dissociation in an amount of 100 m ³ / h. The oxidizing agent (oxygen) is fed into the reaction medium in the zone of carbon oxidation through the side in the amount of 25 m ³ / hour in each oxidation zone. As a result of thermal decomposition, about 200 m / h of hydrogen is formed in the dissociation zone. Carbon in the amount of about 53.6 kg is dissolved in the reaction medium. To mix the reaction medium, including in the horizontal direction, to accelerate the transfer of carbon and the dissociation zone to the oxidation zones, the pressure is increased periodically (every 30 seconds by 30 seconds) in the gas space above the dissociation zone. water pillar. As a result of the interaction of dissolved carbon with an oxidizing agent, about 100 m ³ / h of carbon monoxide (CO) is formed in the oxidation zones. At such costs of raw materials containing carbon and hydrogen and an oxidizing agent, the concentration of carbon in the reaction medium is maintained at 4%. The resulting hydrogen at a temperature of 1500 ° C in a heat exchanger heats the raw material containing carbon and hydrogen before it is fed into the reaction medium to 1400 ° C. Carbon monoxide with a temperature of 1500 ° C in a heat exchanger heats the oxidizer to 1400 ° C. Chilled hydrogen and carbon monoxide are used in the chemical industry to produce methanol. With this organization of the process, there is no heat deficiency in the reaction medium and there is no need for additional heat sources.

Claims

Claim.

Sub. A method of producing hydrogen from a raw material containing carbon and hydrogen, including the formation of a reaction medium from a liquid metal with a temperature above 1200 ° C, with a gas space above its surface, supplying a raw material containing carbon and hydrogen and an oxidizing agent to the reaction medium, characterized in that the reaction the medium consists of two interconnected zones: zones of dissociation of raw materials containing carbon and hydrogen and zones of carbon oxidation, the gas space above these zones is divided, the supply of raw materials containing carbon and hydrogen in the stock medium is carried out in the dissociation zone, the oxidizing agent is fed into the reaction medium in the carbon oxidation zone, the gaseous reaction products are removed separately from the dissociation zone and the carbon oxidation zone, the carbon content in the reaction medium is maintained above 0.5% by mass, the liquid metal of the reaction medium is less affinity for oxygen than carbon.

A.2. The method according to claim 1, characterized in that the reaction medium is circulated in a substantially horizontal direction.

P.Z. The method according to claim 1, characterized in that a pressure close to atmospheric is maintained in the gas space above the reaction medium.

A.4. The method according to claim 1, characterized in that in the gas space above the reaction medium pressure is maintained above atmospheric.

A.5. The method according to claim 1, characterized in that in the gas space above the reaction medium above the dissociation zone and the carbon oxidation zone, the pressures are different.

A.6. The method according to claim 1, characterized in that an alloy consisting mainly of iron is used as the reaction medium.

A.7. The method according to claim 1, characterized in that the feedstock containing carbon and hydrogen and / or an oxidizing agent is preheated.

A.8. The method according to claim 1 and 7, characterized in that the feedstock containing carbon and hydrogen and / or an oxidizing agent is preheated with the heat of the gaseous reaction products.

A.9. The method according to claim 1, characterized in that carbon is additionally supplied to the reaction medium.

A.10. The method according to claim 1 and 9, characterized in that the amount of oxidant supplied to the reaction medium is substantially sufficient to oxidize the carbon supplied to it to carbon monoxide (CO). metal periodically updated.

A.12. The method according to claim 1, characterized in that the reaction medium consists of several zones of dissociation and / or several zones of carbon oxidation.

A.13. The method according to claim 1, characterized in that the gaseous reaction products from the dissociation zone and / or from the carbon oxidation zone are partially burned in the gas space above the reaction medium.

A.14. The method according to claim 1, characterized in that the gaseous reaction products from the dissociation zone and / or from the carbon oxidation zone are partially burned to heat the reaction medium from the outside.