BE1029753A1 - Method of reducing carbon dioxide emissions from an emitter device - Google Patents

Abstract

The present invention relates to a method for reducing the carbon dioxide emission of an emitter device (10), the emitter device (10) generating a carbon-containing gas stream (70), the carbon-containing gas stream (70) being fed into a carbon fixing device (20), the carbon fixing device ( 20) a solid or liquid or gaseous carbon-containing product and a residual gas stream (80) is generated, the residual gas stream (80) being fed to a combustion device (30), the residual gas stream (80) being burned in the combustion device (30) and released to the environment hydrogen is fed to the carbon-containing gas flow (70) before the carbon fixing device (20), characterized in that the residual gas flow (80) before or in the combustion device (30) contains oxygen with at least 50% by volume, preferably at least 90% by volume .-%, particularly preferably at least 95 vol .-%, is supplied.

Description

. BE2021/5717

Method of reducing carbon dioxide emissions from an emitter device

The invention relates to a method for reducing carbon dioxide emissions

emitter device.

It is currently becoming increasingly important to reduce carbon dioxide emissions in order to achieve the legally stipulated climate targets. Various approaches are being pursued for this purpose. For example, attempts are increasingly being made to replace coal-fired power plants with solar or

to replace wind turbines. This is more difficult in production areas in which process-related emissions occur. Only examples are as

Emitter devices here called the coking plants (coal to coke), iron production (ore and coke to iron) or the cement industry (calcium carbonate to calcium oxide). One

One option is to separate the resulting CO2 and store it underground, for example. However, since the risks here are at least difficult to calculate due to an unintentional release of CO2, methods are increasingly being discussed

Convert carbon into other compounds, such as methanol.

US 2007/0244208 A1 discloses the production of a liquid fuel

known as carbon dioxide and water.

WO 2020/048809 A1 discloses a method for producing methanol

Synthesis gas known without the emission of carbon dioxide.

From DE 10 2016 209 026 A1, DE 10 2016 209 027 A1, the

Methods are known from DE 10 2016 209 028 A1, DE 10 2016 209 029 A1 and DE 10 2016 209 037 A1, carbonaceous exhaust gases in a device for binding the

to conduct carbon. For this purpose, the gas mixture is enriched in particular with hydrogen, which originates, for example and in particular, from electrolysis using regeneratively generated electricity. After the mostly incomplete binding of the carbon, the residual gas mixture is incinerated in order to use the remaining calorific value.

However, in order to enable thermal reuse, the residual gas mixture must have a minimum calorific value so that it can be converted into electricity in a power plant in an economically viable manner

; BE2021/5717 or to be used thermally. However, this means that the device for binding the carbon, for example a methanol synthesis, cannot be operated with a maximum yield and so the CO2 emissions can only be partially reduced.

The object of the invention is to increase the binding of CO2 and thus reduce CO2 emissions.

This problem is solved by a method with the specified in claim 1

characteristics. Advantageous developments result from the dependent claims, the following description and the drawing.

The inventive method is used to reduce carbon dioxide emissions

emitter device. Emitter devices are to be understood broadly within the meaning of the invention and are devices that produce a carbonaceous gas stream. This can, for example, mainly have carbon dioxide as the carbon component, for example a cement plant. However, an emitter device can also be used, for example

Produce carbon monoxide-containing gas mixtures, for example a coking plant or a

blast furnace. Usually the process of the emitter device is such that

Carbon emissions are not easily avoidable, as they are regularly caused by the chemical processes taking place or are due to economic reasons

general conditions arise. The emitter device produces a carbonaceous

gas flow. In addition to a carbon-containing gas, the carbon-containing gas stream can also have one or more further gas components. Typically, the carbonaceous gas stream may also contain nitrogen. The carbon-containing gas stream can also contain several carbon-containing gases, such as carbon monoxide, methane and

carbon dioxide. In addition, the carbon-containing gas stream can, for example, also have other components, in particular hydrogen, for example in the

compound with carbon monoxide. Usually and preferably, the carbon-containing gas stream has no oxygen or only very little oxygen

amounts up. The carbon-containing gas stream is directed into a carbon fixer. Carbon fixation devices are straight from the above prior art

technology known. For example, it can be a methanol synthesizer. However, other carbon compounds, for example higher ones, can also be used

Alcohols or hydrocarbon compounds are produced. The synthesis of carbohydrates can also take place in the carbon fixation device. It is essential that the carbon fixation device produces a solid, liquid or gaseous carbonaceous product which is easier to separate and, if appropriate, to landfill than carbon dioxide. Here, the carbon fixation device can be a chemical device or a biotechnological device, for example methanol can be produced both chemically and biotechnologically. To one

To achieve fixation of the carbon in the carbon fixation device, hydrogen is added to the carbon-containing gas stream before the carbon fixation device.

Further, the carbon fixing device generates a residual gas flow. The residual gas stream is fed to a combustion device. The residual gas stream is in the

Incinerator burned and released into the environment in oxidized form.

According to the residual gas stream before or in the combustion device

Oxygen with at least 50% by volume, preferably at least 90% by volume, particularly preferably at least 95% by volume, is supplied. Combustion with air is common, i.e. about a 1:4 ratio of oxygen to nitrogen. The nitrogen reduces the calorific value of the gas mixture.

In the context of the invention, the calorific value given off during combustion is used as the calorific value

Energy value per volume of a gas mixture understood. For the purposes of the invention is the

The calorific value of a gas mixture thus depends on the composition of the gas mixture. While the calorific value of a pure substance, such as methane, a

material constant, the calorific value of a methane-oxygen mixture is higher than one

Methane-air mixture, since in the latter case additional nitrogen is included, which does not contribute to the energy, but lowers the calorific value, since the volume fraction of energy-producing methane and oxygen is reduced. Therefore, within the meaning of the invention, it is not the calorific value of an individual substance, but always of the whole

Gas mixture considered, which is used in combustion.

For example, in order to carry out combustion of the residual gas stream in a conventional manner, the combustible gas mixture of fuel and oxidizing medium should have one

Have a calorific value of about 2.3 MJ per standard cubic meter. So that would have to for the

Combustion with air the residual gas stream has a calorific value of about 4.4MJ each

' BE2021/5717

have standard cubic meters. However, if pure oxygen is used, the mixture of a residual gas flow with only 2.5MJ per standard cubic meter also produces a

Combustion gas mixture with a calorific value of 2.3 MJ per standard cubic meter. The effect is that carbon fixation can be increased from, for example, 75% to 91%, which in turn means that carbon dioxide emissions can be reduced to 1/3, i.e. reduced by 2/3. At the same time, in the event of a

Carbon fixation in the form of methanol increases methanol production by 20%. The figures given here are shown as an example using a pilot plant on the premises of thyssenkrupp Steel in Duisburg and are based on a carbon-containing gas flow of 100 standard cubic meters per hour of metallurgical gases, to which 114 standard cubic meters of hydrogen from water electrolysis are fed. The inventive method can then

Increase methanol production from 1.2 to 1.4 tons per day, CO2 emissions drop from 12 to 4 standard cubic meters per hour. To do this, only 8 of the 57 standard cubic meters of oxygen produced during water electrolysis have to be added to the residual gas stream.

Both products of water electrolysis can thus be used to reduce CO2 emissions. The effort to find a suitable use for the oxygen is reduced or eliminated.

In a further embodiment of the invention, the hydrogen and the

Oxygen generated electrolytically. For this purpose, the electrical energy particularly preferably comes from a regenerative energy source. For this purpose, water is preferably electrolytically split into oxygen and hydrogen.

Since the use of today's natural gas at least partially for CO2-free hydrogen is increasingly being discussed due to the energy transition, in the future the

Electrolysis at the site of carrying out the process according to the invention is increasing

lose meaning.

In a further embodiment of the invention, oxygen from an air separation is supplied to the residual gas stream before or in the combustion device. This

Embodiment is preferred if the hydrogen is taken from a corresponding gas supply, for example, or if the

) BE2021/5717

Combustion device another fuel is supplied, so that the amount of oxygen generated by the electrolysis is not sufficient.

Alternatively, the oxygen from an oxygen supply system, a

vaporization of liquid oxygen or from a biochemical process.

In a further embodiment of the invention, a second fuel is supplied to the combustion device. The second fuel can in particular also be a CO2-neutral fuel. For example, it can be biomass. There

Biomass by the moisture contained and the water content thus generated

Air in the incinerator could also lower the calorific value

Combustion in an oxygen-enriched atmosphere, especially if this is available anyway, for example from water electrolysis, makes sense.

In another embodiment of the invention, the carbon fixation device is used for

maximizing the sequestration of carbon.

In a further embodiment of the invention, the residual gas stream is the

Carbon fixation device partially fed to the carbon-containing gas stream and thus again to the carbon fixation device for further carbon fixation. Through this

Higher rate of carbon fixation is possible with recirculation.

The method according to the invention is explained in more detail below using an exemplary embodiment illustrated in the drawing.

Fig. 1 system for carrying out the method

In Fig. 1, a system for carrying out the method according to the invention is shown in simplified form. An emitter device 10, for example a steel works, generates a carbon-containing gas stream 70 which is fed into a carbon fixation device 20 together with a hydrogen stream 100 which can originate from an electrolyzer 40 or a hydrogen connection 120 from a utility network. Here, a carbon fixation product 140, such as methanol,

° BE2021/5717 produced and thus the carbon is removed from the gas phase. The residual gas flow 80 is fed to a combustion device 30 which burns it and emits it as waste gas 90 via a chimney 60 .

According to the residual gas stream 80 is now an oxygen stream 110 from the

Electrolyzer 40 and/or a second stream of oxygen 130 from an air separation unit 50 is supplied. This reduces the nitrogen content in the combustor 30 and thus increases the calorific value. This allows stronger carbon fixation in the

Carbon fixation device 20 done. This reduces CO2 emissions.

In addition, the combustion device 30 can be supplied with a further fuel 150, for example coal, pulverized coal, natural gas or hydrogen. Likewise, the combustion device 30 can have another oxidizing agent 160, for example

Air, oxygen-enriched air or pure oxygen are supplied. This can be preferred, for example, in order to ensure constant and reliable generation of energy in the combustion device 30 . The inflow quantity of the additional fuel 150 is preferably regulated as a function of the quantity of the residual gas flow 80 supplied to the combustion device 30 .

Reference numeral 10 emitter device 20 carbon fixation device 30 combustion device 40 electrolyzer 50 air separation 60 chimney 70 carbonaceous gas stream 80 tail gas stream 90 exhaust gas 100 hydrogen stream 110 oxygen stream 120 hydrogen connection 130 oxygen stream of air separation 140 carbon fixation product

150 more fuel 160 more oxidizer

Claims (6)

patent claims 1. Method for reducing the carbon dioxide emission of an emitter device (10), wherein the emitter device (10) generates a carbon-containing gas stream (70) 5, wherein the carbon-containing =— gas stream (70) is passed into a carbon fixation device (20), the carbon fixation device ( 20) a solid, liquid or gaseous carbon-containing product and a residual gas stream (80) is generated, the residual gas stream (80) being fed to a combustion device (30), the residual gas stream (80) being burned in the combustion device (30) and released to the environment hydrogen is fed to the carbon-containing gas stream (70) before the carbon fixing device (20), characterized in that oxygen with at least 50% by volume is fed to the residual gas stream (80) before or in the combustion device (30). 2. The method according to claim 1, characterized in that the hydrogen and the oxygen are generated electrolytically. 3. The method according to any one of the preceding claims, characterized in that the residual gas stream (80) before or in the combustion device (30) oxygen from an air separation (50) is supplied. 4. The method according to any one of the preceding claims, characterized in that the combustion device (30) is supplied with a second fuel. 5. A method according to any one of the preceding claims, characterized in that the carbon fixation device (20) is operated to maximize the sequestration of carbon. 6. The method according to any one of the preceding claims, characterized in that the residual gas stream (80) of the carbon fixation device (20) is partially fed to the carbon-containing gas stream (70) and thus again to the carbon fixation device (20) for further carbon fixation.