DE102010011870B4 - Method and device for storing CO2 - Google Patents

Abstract

Method for storing CO2 from exhaust gases or flue gases, which is separated from combustion and / or production and / or energy systems, and is then pumped into underground storage facilities, according to the preamble of claims 1 and 11. In order to achieve that the storage of the CO2 in the earth's deposits is either superfluous, or at least reversible over a longer period of time in such a way that the stored CO2 does NOT escape directly into the atmosphere, it is proposed according to the invention that the CO2-containing Residual gas or the separated CO2 gas is at least partially fed into a biomass reactor for CO2 fertilization of aquatic plant cultures, in such a way that there is a combination of CO2 bound in biomass and the pumping of the remaining CO2 into earth deposits.

Description

The invention relates to a method and a device for storing CO ₂ from exhaust gases or flue gases, which is separated from incineration and / or production and / or energy systems, according to the preamble of claim 1 and 11.

The operation of fossil fuel-fired power plants will play an important role in the transitional period of conversion to renewable energy sources. At the same time, measures to protect the climate are already being taken.

Thus, in this context, methods are known in which the subsequent separation of CO _{2 is} already taken into account in the energy generation process. In this case, there is no direct burning when burning the coal, but first the coal gasification with a combined CO ₂ separation. Electricity is then generated in gas and steam turbines. It is initially generated flammable raw gas. Already here is a CO ₂ separation.

This CO ₂ should then be pumped in a known manner in earth deposits.

Overall, the process is effective in terms of CO ₂ disposal in the use of the fossil energy coal, but it comes in the ground only under certain conditions and then only very slowly in time to a mineral and thus solid bond of the injected CO ₂ . Nevertheless, CO ₂ levels can outgas over time.

So is out of the EP 1 967 249 A1 a method is known in which a CO ₂ separation takes place from exhaust gases. This is done by a two-phase distillation.

From the EP 0 613 856 B1 Another method for the separation of CO ₂ and sulfur from exhaust gases is known.

The separation of CO ₂ from exhaust gases is only a measure for the real climate-relieving "disposal" of CO ₂ . Subsequently, even the dumping of this CO ₂ in earth deposits is necessary.

The invention is therefore based on the object to further develop a method and a device of the generic type such that the storage of CO ₂ in the earth's deposits either superfluous, or at least over a longer period of time is reversible so that the stored CO _{2 is} NOT back out directly into the atmosphere.

The object is achieved according to the invention in a method of the generic type by the characterizing features of claim 1.

Further advantageous embodiments are specified in the dependent claims 2 to 10.

With regard to a device, the object is achieved by the characterizing features of claim 11.

Further advantageous embodiments are specified in the remaining dependent claims.

Core of the inventive method is that already in the separation process of CO ₂ from the exhaust gas / flue gas, the CO ₂ -containing residual gas or the separated CO ₂ gas is at least partially conducted in a biomass reactor for CO ₂ fertilization of aquatic plant cultures, or semi-cultures or hydroponics in such a way that it leads to a combination of biomass-bound CO ₂ and the pumping of the remaining CO ₂ into earth deposits.

Semi-cultures are plant cultures in clay substrate. It is known that large amounts of CO _{2 are} extremely growth promoting act on aquatic plants, especially Lemnacea (duckweed). The combination of separation of the separated biomass-bound CO ₂ streams in aquatic crops, on the one hand, and encapsulation of the remainder of CO ₂ in earth deposits, on the other hand, has the enormous advantage of significantly increasing the available resources of the earth's deposits. It can therefore be stored much longer.

The combination of both processes thus leads to a temporal moderation of sustainable CO ₂ binding.

The binding of at least a portion of the CO ₂ in particular aquatic cultures thus has the further advantage that it leads to a splitting of the incorporation of CO ₂ . For example, part of it is made as gas in earth deposits according to the known methods, and another part can be backfilled biomass-bound, ie solid-bound in earth deposits, for example in old exploited coal lumps.

Other advantages result from the further inventive embodiment of the method.

In a further advantageous embodiment, it is proposed that the feed operation of CO ₂ in the biomass reactor is coupled to the CO ₂ separation process in such a way that CO ₂ either after the so-called CO ₂ shift with water by the coal gasification process and / or after the sulfur purification stage is removed. Thus, the well-known so-called CCS process (carbon capture and storage) can be ingeniously combined with the operation of a biomass reactor and CO ₂ -effective. This can already be achieved in the multistep process in intermediate stages in which already concentrated CO ₂ is present. Thus, there is a division of the resulting CO ₂ gas streams. So only a part of the CO ₂ is then pumped into the earth deposits or pressed. This leads to a cost reduction of the CCS process because it is no longer necessary to concentrate the entire amount of exhaust gas up to highly pure CO ₂ , since the CO ₂ deposited for the biomass reactor does not have to be highly pure, since it is diluted to the plant's needs anyway.

In a further advantageous but alternative embodiment, it is provided that the biomass reactor is placed in the vicinity of the borehole of the earth deposit for injecting CO ₂ , such that the CO ₂ which escapes continuously from the borehole is fed directly to the biomass reactor.

In conventional practice, the CCS method is intended to press the CO ₂ into deep layers of soil or Erdlagerstätten and close the well at the end with a tight closure, for example by pouring concrete. With this embodiment according to the invention, however, the earth deposit is provided only as a CO ₂ buffer. D. h it is pressed depending on the amount of CO ₂ amount of the same in the earth deposit, and then then moderately re-off, the outgassing CO ₂ gas is fed directly to a biomass actuator. This completely eliminates the time-consuming sealing closure with the necessary considerable amounts of CO ₂ . Instead, you may need only a kind of metering valve for the controlled discharge of the stored CO ₂ and inlet into the biomass reactor. The big advantage of combining the deposit-bound CO ₂ storage and the biomass reactor is therefore that at the latest the CO ₂ outgassing from the earth deposit is immediately active, ie biochemically and thus solid-bound. Thus, the earth deposit is a CO ₂ buffer, from which the biomass reactor moderated then the outgassing or pumped out CO ₂ binds.

The biomass reactor can also be erected directly above the borehole. The biomass reactors can reach sizes of one hectare (10,000 square meters) of floor space, and with the stacked shelves of cultivated areas contained therein, 50 to 100 times the surface area of cultivated areas is achieved.

Their CO ₂ binding capacity when using Lemnacea (duckweed) can easily reach 100,000 tonnes CO ₂ / year and more, with only one such biomass reactor. In a multiple arrangement of such systems, therefore, respectable CO ₂ binding capacities can be achieved.

The direct attack of CO ₂ even in peak workloads can be disposed of through the earth deposits. By contrast, CO ₂ solid binding in the biomass reactor takes place steadily. Therefore, the combination of both processes is so beneficial.

In a further advantageous embodiment, it is provided that the biomass actuator is also placed on the rest of the earth CO ₂ outgassing bodies such as disused coal mines, or sites of geological CO ₂ degassing from the ground, or in the vicinity of strong CO ₂ emitters, and absorbed by suction and optionally the CO ₂ content of the sucked air is concentrated before it is introduced into the biomass reactor. The biomass reactor can not only be provided with a direct supply line for CO ₂ , but it can also be fed to corresponding CO ₂ outgassing locations by suction of the same from the environment. It should be noted that the biomass reactor inside can realize an exposure to CO ₂ of at least 5,000 ppm CO ₂ . As already mentioned, natural CO ₂ emitters, such as coal mines etc, can be used to place the biomass reactor.

In a further advantageous embodiment it is stated that the biomass thus obtained is dried and stored. It should be noted that despite their short generation cycle of one to a few days, Lemnacea has a carbon content of 44% to 48% in the dry matter due to its enormous carbon dioxide resorption behavior. As I said, this is a plant that doubles every 1 to 5 days. This creates a biological carbon reservoir with a high mass potency by doubling the biomass every 1 to 5 days.

As a result, significant amounts of carbon dioxide can be absorbed and bound, rather than by any other biomass. This applies to the plant species of Lemnacea. Likewise, this biomass is far easier to handle than algae.

In a further advantageous embodiment, it is stated that the biomass thus obtained is dried and stored after Heißverkokung as carbon solid. This creates a significant compacting, because only the carbon contained is stored.

In a further advantageous embodiment, it is stated that the biomass thus obtained is dried and fed together with the fossil energy carrier in a coal gasification process for producing highly combustible raw gas of high pressure.

From the prior art, the said coal gasification process for obtaining highly combustible raw gas at about 35 bar pressure is known. Two energy levels can be used. On the one hand, the high pressure, which is released via a gas turbine, and a subsequent combustion of the gas for steam generation and energy use by means of a steam turbine.

In this two-stage energy generation process, the said biomass can now be fed back with, and be recovered together with the injected coal, the raw gas.

By regenerating the biomass produced from the CO ₂ cycle, the energy production process can be included in the legally required framework on the fuel side by CO ₂ -neutral biomass.

The joint gasification of coal and dried biomass of the type mentioned, with high carbon content, also an efficient energy production with savings in the amount of coal as a primary energy source is possible. In addition, the biomass can be so fed into the said modern energy production process at the same time, as well as coupled with the above-mentioned CCS method for carbon dioxide binding.

In a further advantageous embodiment it is specified that aquatic plants, such as Lemnacea, and / or semi-cultivated plants and / or hydroponic plants and / or algae are used as biomass plants. A mixed culture is also possible.

Furthermore, it is advantageously configured that flue gas is fed from an exhaust pipe of a combustion power plant or an industrial plant in unmodified form or in processed by gas scrubbing form in the biomass reactor.

With regard to a device of the generic type, the essence of the invention is that the multi-stage separation process of the CO ₂ from the exhaust gas / flue gas of the CO ₂ -containing residual gas or the separated CO ₂ gas is coupled to a gas supply of a biomass reactor such that the introduced CO ₂ gas is used for CO ₂ fertilization of aquatic plant cultures, which performs a biochemical CO ₂ -fixation, such that it leads to a combination of bound in biomass CO ₂ and the pumping of the remaining CO ₂ in earth deposits.

In a further advantageous embodiment, it is provided that the biomass reactor is placed in spatial proximity to a carbon dioxide separation device and / or in the vicinity of the Einpresstelle (borehole) of CO ₂ in the earth deposit. Thus, it is now possible that the amount of CO ₂ , which is metabolized by the aquatic plant cultures, the biomass reactor is fed directly.

In the case of placement of a biomass reactor above or near the well of the CO ₂ injection site into the earth deposits, the outgassing therefrom is immediately and consistently resorbed by the biomass reactor. Thus, the permanent closure of such a hole with concrete is completely superfluous. Instead, however, a valve means may be located at the well, so that the CO ₂ gassing -Stoffwechselkapazität of crops can be adjusted in the biomass reactor ₂ amount to the CO.

In a further advantageous embodiment, it is stated that the device is provided with a harvesting device which effects a flow of biomass from the biomass reactor to the coal gasification device, and that means for simultaneously drying the biomass are also provided in this material flow. This ensures that a logistically simple and energy-saving recovery can take place so that the overall CO ₂ balance remains optimal.

In a further advantageous embodiment, it is provided that before the introduction of the CO ₂ in the biomass reactor, a water reservoir is provided, in which by pressure feed CO ₂ is cacheable, and then can be fed by cold fogging in the biomass reactor. This can also be done as an alternative to the temporary storage of CO ₂ . Thus, the accumulating CO ₂ amounts can be buffered so to speak until it is introduced into the biomass reactor. A water reservoir can be created in silos, coal mines or lakes covered with foils.

In a further advantageous embodiment, it is provided that the biomass reactor is a mobile device which consists of mobile or foldable or inflatable foil elements or chambers, which are gas-barrier but translucent.

The invention is illustrated in the drawing and explained in more detail below.

It shows:

1 : Overview of Procedural Measures

2 : Introduction of CO ₂ into the soil as a buffer

3 : Removal from the earth deposit by valve

1 shows the graphical representation of the combined process measures. The left part of the picture shows the known process for the production of highly combustible crude gas from coal according to CCS. Unlike the direct combustion of coal, the coal is processed or treated here so that a coal gasification takes place. Carbon monoxide CO, hydrogen H ₂ , carbon dioxide CO ₂ and methane CH ₄ are produced as gas components. This involves a so-called CO ₂ shift with water, by the reaction CO + H ₂ O → CO ₂ + H ₂ expires. This is followed by the purification of sulfur and then the CO ₂ separation and compression.

The raw gas is at a pressure of 35 bar and can therefore be used in two stages energetically. On the one hand, the raw gas is first released via a gas turbine, and then then burned and the heat is used by steam generation and thus operated a steam turbine. Ab initio, therefore, is another implementation of the energy of coal. It is now possible to effectively separate the resulting CO ₂ .

Now, at the process stages "CO ₂ shift" and / or after the sulfur purification, a first and / or a second CO ₂ gas discharge is carried out. The CO ₂ produced in this coal gasification process is then fed into a closed biomass reactor containing cultivated areas with aquatic plants. In this case, Lemnacea are preferably used, which have a significantly high CO ₂ conversion at significantly increased growth. There, the injected CO _{2 is} then converted into biomass and thus bound biochemically.

The fed CO ₂ can either be introduced as gas or fed into water, if necessary, also be dissolved as hydrogen carbonate.

The use of the aquatic plants Lemnacea (duckweed) has the advantage that this plant has an assimilation surface for CO ₂ in the water as well as above the water surface. Thus, the CO ₂ can be offered as a gas as well as dissolved in water of the plant. When dissolved in water, there is the advantage that the CO ₂ outgases slowly, and the plant is so moderated time available.

Thus, it comes to an advantageous combination of the known method with the at least partial binding of CO ₂ in biomass. In order to provide the biomass reactor further favoring Massenwuchsparamter available, and the heat balance can be coupled together, in such a way that the resulting residual heat is used to heat the biomass reactor with. Thus, the biomass reactor can also be heated by the winter simply by otherwise no longer usable waste heat, and the mass production of Lemnacea goes continuously through the winter.

This is a variant of the combination of the known as CCS method with the biomass reactor of the type mentioned. A further variant shows 2 , This is the biomass reactor 2 on or near the Einspresstelle 4 of CO ₂ into the soil 5 arranged. In the known CCS method according to 1 separated CO ₂ then pumped into the ground, in about 700 meters depth or more. The CO _{2 is} there in soil layers 5 pressed in, which is to hold the CO ₂ . For safety, the holes 4 but closed to prevent backflow. In a further embodiment, a biomass reactor can now use the backflow of CO ₂ instead of suppressing it, for the continuous introduction of CO ₂ into the biomass reactor.

Ie. in other words, that's from the CCS process 1 accumulating CO _{2 is} pumped into the earth's deposits, and that the there then pumped stock of CO ₂ successively, at least to the extent that outgases back, can be used to bind the CO ₂ in biomass.

In this respect, the deposit is then not a permanent depot, but only a memory or buffer to deposit large amounts of CO ₂ safely first, but to remove them over a longer period of time and bind biologically.

Due to the high CO ₂ conversion of Lemnacea, the metabolised CO _{2 is} thus not a problem substance but a real raw material.

3 shows this long-term variant, where the borehole 4 is not poured with concrete, but with a valve, for the metered intake of that amount of CO ₂ , from the Erdlager 5 into the biomass reactor 2 , which is constantly metabolized by the Lemnacea in biomass reactor, and achieved enormous growth promotion. The CO ₂ concentrations are in such biomass reactors 2 at 5,000 ppm and more.

Thus, the variants arise in which according to 2 the biomass reactor 2 already fed at the time of introduction into the ground with flowing CO ₂ , or according to 3 in which the biomass reactor 2 after the introduction of CO ₂ into the soil, the so-used CO ₂ depot over a long time uses.

The large quantities of the aquatic plants produced in this way can at least partially be added as a renewable, CO ₂ -neutral dried raw material of coal gasification, because the proportion of carbon in the dry matter in Lemnacea after all, is 44 to 48%. This results in closed material cycles.

However, the dry mass produced can also be hot-coked and then re-filled as pure carbon in solid, non-gassing form in old empty mine shafts. In this way, the carbon would even be directly solid-bonded and thus safely and permanently bound.

LIST OF REFERENCE NUMBERS

1

CCS process or power plant chimney as CO ₂ source

2

biomass reactor

3

CO2 line

4

Einpresstelle / borehole

5

soil

6

Valve

7

well

Claims (15)

A method for storing CO ₂ from exhaust gases or flue gases, which is separated from incineration and / or production and / or energy systems, and is pumped afterwards in earth deposits, characterized in that already in the separation process of CO ₂ from the exhaust gas / flue gas the CO ₂ -containing residual gas or the separated CO ₂ gas is at least partially conducted into a biomass reactor for CO ₂ fertilization of aquatic plant cultures, or semi-cultures or hydroponics, such that it results in a combination of biomass-bound CO ₂ and the pumping of the remaining CO ₂ comes in earth deposits. A method according to claim 1, characterized in that the feed operation of CO ₂ in the biomass reactor is coupled to the process for CO ₂ separation such that CO ₂ either after the so-called CO ₂ shift with water after the coal gasification process and / or after Sulfur purification stage is taken. A method according to claim 1, characterized in that the biomass reactor is placed in the vicinity of the borehole of the earth deposit for the injection of CO ₂ , such that the steadily escaping from the borehole CO _{2 is} fed directly to the biomass reactor. A method according to claim 3, characterized in that the biomass reactor is placed directly on or above the borehole to the earth deposit. Method according to one of the preceding claims, characterized in that the biomass actuator is also placed on other out of the ground CO ₂ outgassing bodies such as disused coal mines, or sites of geological CO ₂ degassing from the soil, or in the vicinity of strong CO ₂ - Emitters and absorbed by suction and optionally the CO ₂ content of the sucked air is concentrated before it is introduced into the biomass reactor. Method according to one of claims 1 to 5, characterized in that the biomass thus obtained is dried and stored. Method according to one of claims 1 to 5, characterized in that the biomass thus obtained is dried and stored after Heißverkokung as carbon solid. Method according to one of claims 1 to 5, characterized in that the biomass thus obtained is dried and fed together with the fossil energy carrier in a coal gasification process for the production of high-flammable raw gas high pressure together with the fossil energy carrier. Method according to one of claims 1 to 8, characterized in that as biomass plants aquatic plants, such as Lemnacea, and / or semi-cultivated plants and / or hydroponic plants and / or algae are used. Method according to one of claims 1 to 9, characterized in that flue gas is fed from an exhaust pipe of a combustion power plant or an industrial plant in unaltered form or in processed by gas scrubbing form in the biomass reactor. Device for storing CO ₂ from exhaust gases or flue gases, which is separated from incineration and / or production and / or energy systems, and is pumped afterwards in earth deposits, characterized in that the multi-stage separation process of CO ₂ from the exhaust gas / flue gas the CO ₂ -containing residual gas or the separated CO ₂ gas with a gas supply line ( 3 ) of a biomass reactor ( 2 ) is coupled in such a way that the introduced CO ₂ gas is used for the CO ₂ fertilization of aquatic plant cultures, which performs a biochemical CO ₂ -fixation, such that it results in a combination of biomass-bound CO ₂ and the pumping of the remaining CO ₂ into earth deposits ( 5 ) comes. Device according to claim 11, characterized in that the biomass reactor ( 2 ) in close proximity to a carbon dioxide separation device and / or in the vicinity of the point of injection of the CO2 into the earth deposit ( 5 ) is placed. Device according to claim 11 or 12, characterized in that the device is provided with a harvesting device which generates a stream of biomass from the biomass reactor ( 2 ) to the coal gasification facility ( 1 ), and that means for simultaneous drying of the biomass are provided in this material flow at the same time. Device according to one of claims 11 to 13, characterized in that before introduction of the CO ₂ into the biomass reactor ( 2 ) a water reservoir is provided in which CO ₂ can be buffered by pressure feed, and by cold fogging into the biomass reactor ( 2 ) can be fed. Device according to one of claims 11 to 14, characterized in that the biomass reactor ( 2 ) is a mobile device which consists of mobile or foldable or inflatable foil elements or chambers which are gas-barrier but translucent.

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