EP2475451A1

EP2475451A1 - Method for removing co2 from exhaust gases, such as exhaust gases from plants for producing raw iron or exhaust gases from syngas plants

Info

Publication number: EP2475451A1
Application number: EP10754453A
Authority: EP
Inventors: Robert Millner; Jan-Friedemann Plaul; Johannes Leopold Schenk; Kurt Wieder
Original assignee: Siemens VAI Metals Technologies GmbH Austria; Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: Primetals Technologies Austria GmbH; Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2009-09-11
Filing date: 2010-09-07
Publication date: 2012-07-18
Also published as: JP2013504413A; RU2012114121A; CA2773766A1; BR112012005539A2; KR20120089481A; US20120237421A1; AT508250B1; AT508250A4; AU2010294332A1; CN102481516A; WO2011029814A1

Abstract

The invention relates to a method for removing CO₂ from exhaust gases (9), such as exhaust gases from plants for producing raw iron or exhaust gases from syngas plants, wherein the CO₂ is removed by means of chemical and/or physical absorption (14), wherein the heat for regenerating the absorption agent is at least partially obtained from an air fractionation system (23). The CO₂ can thereby be separated from other gases from the exhaust gases to a greater degree than for pressure swing adsorption, and a lower-quality energy carrier can nevertheless be used therefor.

Description

Method for removing CO ₂ from exhaust gases, such as exhaust gases from pig iron production plants or exhaust gases

Synthesis gas plants The invention relates to a process for the removal of CO ₂ from exhaust gases, such as exhaust gases from plants for the production of pig iron or exhaust gases from synthesis gas plants, and to a corresponding plant. For the production of pig iron, which should also include the production of pig iron-like products, there are essentially two known common processes: the

Blast furnace process and smelting reduction. The blast furnace process first produces pig iron from iron ore using coke. In addition, scrap can also be used. Thereafter, steel is produced by further processes from pig iron. The iron ore is used as lump, pellets or sinter together with the reducing agents (usually coke, or coal, for example in the form of a

Fine coal indisposition plant) and other constituents (limestone, slag formers, etc.) are mixed to form the so-called Möller and then charged into the blast furnace. The blast furnace is a metallurgical reactor in which the Möllersäule reacts in countercurrent with hot air, the so-called hot blast. By burning and gasifying the carbon from coke and coal, the necessary heat for the reaction and carbon monoxide or hydrogen, which forms a substantial part of the

Represents reducing gas and flows through the Möllersäule and reduces the iron ore. The result is pig iron and slag, which are tapped periodically.

In the so-called oxygen blast furnace, which is also referred to as blast furnace with Topgas- or top gas recirculation, in the gasification of coke or coal oxygen-containing gas with more than 90% oxygen content (0 ₂ ) injected into the blast furnace. For the emerging from the blast furnace gas, the so-called Top ^¬ or top gas, a gas cleaning must be provided (eg dust and / or cyclones in combination with

Wet scrubbers, bag filter units or hot gas filters). Furthermore, the oxygen blast furnace usually a compressor, preferably with aftercooler, for in the blast furnace

recycled top gas provided and a device for C0 ₂ ~ removal, according to the prior art usually by means of pressure swing adsorption.

Further options for the design of a

Blast furnace methods are a heater for the reducing gas and / or a combustion chamber for partial combustion with oxygen.

The disadvantages of the blast furnace are the demands on the feedstock and the high emission of carbon dioxide. The iron carrier used and the coke must be lumpy and hard, so that sufficient cavities remain in the Möllersäule, which ensure the flow through the blown wind. The C0 ₂ output represents a strong

Environmental impact. Therefore, there are aspirations that

Replace blast furnace route. To call here are the

Natural gas sponge iron production (MIDREX, HYL, FINMET) and smelting reduction processes (Corex and Finex processes).

In the smelting reduction, a melter gasifier is used, in which hot liquid metal is produced, and at least one reduction reactor in which the carrier of the iron ore (lump, fine ore, pellets, sinter) with

Reduction gas is reduced, the reducing gas in the melter gasifier by gasification of coal (and

optionally a small proportion of coke) with oxygen (90% or more) is produced. Also in the smelting reduction process are usually

- Gas purification plants (on the one hand for the top gas from the reduction reactor, on the other hand for the reducing gas from the melter gasifier),

a compressor, preferably with an aftercooler, for the reducing gas recycled to the reduction reactor,

- A device for C0 ₂ ~ removal, according to the prior art usually by means of pressure swing adsorption

- And optionally a heater for the reducing gas

and / or a combustion chamber for partial combustion with oxygen provided.

The Corex process is a two-step process

Smelting reduction. The smelting reduction combines the process of direct reduction (prereduction of iron to sponge iron) with one

Melting process (main reduction).

The well-known Finex method corresponds in

Essentially the Corex process, but iron ore is introduced as fine ore.

If the C0 ₂ ~ emissions into the atmosphere in the production of pig iron to be substantially reduced, it must be saved from the exhaust gases from the production of pig iron and deposited in bound form (ger .: CO ₂ capture and sequestration (CCS)).

The invention can be applied not only to pig iron production but also to synthesis gas plants.

Synthesis gases are all hydrogen-containing and usually also CO-containing gas mixtures, which in a synthesis reaction for

Should be used. Synthesis gases can be made from solid, liquid or gaseous substances.

In particular, this includes coal gasification (coal is converted with water vapor and / or oxygen to hydrogen and CO) and the production of synthesis gas from natural gas (Reaction of methane with water vapor and / or oxygen to hydrogen and CO). Synthesis gas plants also produce unwanted CO2, which has to be separated. For the deposition of CO2 so far mainly the

Pressure swing adsorption (PSA - Pressure Swing

Adsorption), in particular also the vacuum pressure swing adsorption (English: VPSA - Vacuum Pressure Swing Adsorption) used. Pressure swing adsorption is a physical process for the selective decomposition of gas mixtures under pressure. Special porous materials (eg activated

Silica (Si0 ₂ ), activated alumina (Al ₂ O ₃ ),

Zeolites, activated carbon or combined use of these

Materials) are used as a molecular sieve to molecules according to their adsorption and / or kinetic

Diameter to adsorb In the PSA is exploited that gases adsorb different amounts of surfaces. The gas mixture is introduced into a column under a precisely defined pressure. Now adsorb the unwanted

Components (here CO2 and H ₂ 0) and the recyclable material (here CO, H ₂ , CH ₄ ) flows predominantly unhindered through the column. Once the adsorbent is fully loaded, the pressure will be

dismantled and flushed the column. To operate a (V) PSA plant, electrical power is needed to compress the CO2-laden feed gas.

The product gas stream after the pressure swing adsorption, which contains the recyclables, contains in exhaust gases from the

Pig iron production still about 2-6 vol% CO2. However, the residual gas stream from the (V) PSA plant still contains relatively high reducing gas components (such as CO, H ₂ ), which are responsible for the

Lost pig iron production.

The residual gas stream after pressure swing adsorption, which contains the undesirable components, is typically composed of exhaust gases from pig iron production as follows: Compound% vol at VPSA vol% at PSA

H ₂ 2.2 5.5

N ₂ 1.5 2.4

CO 10.9 16.8

C0 ₂ 82.1 72.2

CH ₄ 0, 7 0.9

H ₂ 0 2, 6 2.2

The residual gas can not simply be thermally recycled because it - due to the low and / or fluctuating

Calorific value of about ± 50% - would have to be enriched with other fuels. It would also calculate the calorific value of the export gas (= that part of the top gas withdrawn from the process of pig iron production)

Reducing pig iron production, if it is mixed to the top gas of the blast furnace or smelting reduction, which subsequently also the efficiency of a supplied with the export gas power plant, such as a combined cycle power plant (CCPP) due to the high

Fuel gas compression and the lower efficiency of the gas turbine reduced. At a steam power plant or

Boiler would increase the flame temperature during the

Combustion can be reduced.

If the C0 ₂ is to be bound from the residual gas, the residual gas must be compressed so that the CO _{2 is} typically in liquid form, and then the liquid CO ₂ must be introduced into a reservoir, to which the pressure usually has to be increased so far that the CO _{2 is} in the

liquid-solid or supercritical state where CO _{2 has} a density of about 1000 kg / m ³ .

The supercritical state is a state above the critical point in the phase diagram (see FIG. 1), which is obtained by adjusting the densities of the liquid and gas phases is marked. The differences between the two

Physical states stop existing at this point.

To such a high compression must be a multi-stage

Compressor with high performance can be used to bring the typical densities at line level, which is approximately in the range of greater than 0 ° C and greater than 70 bar (7,000,000 Pa), preferably at 80-150 bar in ambient

Temperatures, is.

However, the residual gas from a (V) PSA is not suitable for being bound because, in addition to CO _{2, it has} a relatively high proportion of CO, H ₂ , N ₂ , CH ₄ , etc. On the one hand, the CO share poses a security risk, since this is the case with a

Leakage can endanger persons (CO intoxication) and in some circumstances can lead to ignition or explosion. Furthermore go the "impurities" CO, H ₂ , ... of C0 ₂ for the

Energy production or reduction work lost and affect the physical properties of the

compressed gas, which also fluctuate due to the fluctuating levels of CO, H ₂ , etc., and the measurability, the compression, the water solubility and the

Vary transport properties. Contaminants must also reduce the distances between stations where the transported liquefied gas mixture must be re-compressed, increasing operating costs due to additional compressors or pumps and their energy requirements. Or, the inlet pressure in the line must be increased to reduce the number or power of the additional pumps and compressors along the line.

Investigations concerning the influence of impurities on the transport of liquefied gases have been conducted and published by Newcastle University

http: // ww. geos. ed. ac. uk / ccs / UKCCSC / Kewcast le 2 07.ppt. A diagram for this is shown in FIG. 2. It is therefore an object of the invention to separate CO ₂ from exhaust gases of pig iron production or synthesis gas production to a greater extent than (V) PSA from other gases, but in addition to use a lower energy source than (V) PSA.

The object is achieved by a method according to claim 1, by the CO _{2 is} removed by means of chemical and / or physical absorption, wherein the heat for the regeneration of the absorbent is at least partially (preferably entirely) from a Luftzerlegungsanlage.

"Air separation plant" means a plant in which air is first compressed, liquefied and then broken down into individual components (oxygen, nitrogen, noble gases).

By using a chemical and / or physical absorption process, the proportions of the for the

Pig iron production recovered gases CO, H ₂ , CH ₄

increased compared to a (V) PSA and the C0 ₂ ~ share in

Product gas can be significantly reduced (down to a few ppmv). The use of waste heat from an existing one

Plant, here an air separation plant, is more cost-effective than the production of steam with its own aggregate only for desorption. In addition, the use of a

low-energy source such as hot air from an economic and ecological point of view a high-quality energy source such as

To prefer steam. The removal of heat from a running air separation plant is also more flexible than the generation of steam in a specially for the C0 ₂ ~ operated steam generator. Furthermore owns one

Luftzerlegungsanlage a very high availability, which is higher than that of a pig iron production plant. The combination of air separation equipment on the one hand and

Crude iron or synthesis gas production, on the other hand, is also advantageous because the oxygen separated off in the air separation plant in the pig iron or pig iron

Synthesis gas production can be used.

The residual gas stream after chemical and / or physical absorption mainly contains CO2 and after removal of H ₂ S only traces of H ₂ S and can therefore be discharged directly into the atmosphere and / or just a C02 compression followed by CC> 2- Storage be supplied (Engl .:

Sequestration, eg EOR - enhanced gas recovery) and / or as a substitute for N ₂ in iron production and coal gasification: the residual gas stream consists mainly of CO2 and can therefore be used for charging equipment, barrier seals and selected flushing and Kühlgasverbraucher be used.

Due to the low content of impurities, the energy required for the compression of the residual gas stream from the chemical and / or physical absorption up to

liquid-solid or supercritical state (> 73.3 bar) about 20-30% lower than for residual gas from a (V) PSA.

Consequently, the distances between the stations increase in the gas lines, where the gas must be re-compressed. Both the acquisition costs and the

Operating costs for CO 2 treatment are thereby reduced. Compared to the pressure swing adsorption works the

chemical and / or physical absorption with lower pressures on the gas to be cleaned and a lower one

Pressure drop in the removal of CO2, so that energy is saved here. In contrast to a VPSA, no vacuum compressors are needed, which also consume a lot of energy. The low energy consumption is present especially for those countries where energy is scarce and / or expensive.

Due to the now higher proportion of combustible substances in the invention purified exhaust gas of pig iron production or synthesis gas production, the system performance can be increased or reduced their specific consumption or even in the combustion of this gas in a power plant, a higher efficiency of the power plant can be realized.

The investment costs for a chemical and / or

Physical absorption methods are comparable to those for a VPSA plant. But the absorption process needs large amounts of heat. This heat would be expensive if it had to be specially made and could not be provided by means of an already existing heat source.

Chemical absorption methods are characterized in that the gas to be separated with the absorbent

partially or completely solid or loose chemical bond enters. In a physical

Absorption process, the gas to be separated without

Change of its material properties in the

Absorbents dissolved, it act the Van der Waals forces. In addition, there are still methods in which both chemical and physical bonding forces come into play and which are referred to as hybrid washes.

There are several chemical absorption methods suitable for this invention:

A first absorption process is characterized by the use of potassium carbonate as the absorbent. It is used hot potassium carbonate (English Hot Potassium

carbonate (HPC) or "hot pot"). Depending on the supplier of this process, various substances are added to the potassium carbonate: activators, which increase the CO 2 deposition and inhibitors which should reduce corrosion. A widely used method of this type is known as the Benfield method and is offered by UOP. The Benfield process requires about 0.75 kg of steam per Nm ³ of gas to be purified.

A second absorption process is known as amine scrubbing with several sub-processes. In a first step, slightly alkaline aqueous solutions of amines are used

(Mostly ethanolamine derivatives) are used, which absorb the acidic gases, such as CO ₂ reversibly chemically. In a second process step, the acidic gas becomes thermal

(By heating) again separated from the amine and the recovered amine used again for washing.

Known methods for this are the Amine Guard FS method from UOP, which reduces the C0 ₂ content to 50 ppmv and the H ₂ S content to 1 ppmv. The steam demand of this process is about 1.05 kg steam per Nm ³ of gas to be purified.

Amines, such as diethanolamine (DEA), are also used as activators for absorption processes using potassium carbonate, such as the Benfield process.

For amine scrubbing primary amines can be used, such as methylamine, monoethanolamine (MEA) and / or diglycolamine

(DGA).

For amine scrubbing, secondary amines may be used in addition to or as an alternative to primary amines, such as

Diethanolamine (DEA) and / or diisopropanolamine (DIPA).

In addition or as an alternative to primary and / or secondary amines, it is also possible to use tertiary amines, for example triethanolamine (TEA) and / or methyldiethanolamine (MDEA). An existing process for this is the aMDEA process of BASF (offered by Linde and Lurgi), which activated methyldiethanolamine (MDEA) is used. Of the

Steam requirement of this method is about 0.85 kg steam per Nm ³ gas to be cleaned. There are also various physical absorption methods that are suitable for this invention, some of the most important representatives are the so-called Purisol® process, the

Rectisol® method and the Selexol method. The Purisol® process utilizes N-methyl-2-pyrrolidone (NMP) as the absorbent, regenerating the

Absorbent takes place by means of steam via indirect

Heat exchanger, wherein the steam demand at about 1417 kg / MM scf = about 0.050 kg / Nm ³ , is. All types of heat exchange media can be used: air, nitrogen, steam, thermal oil, etc.

In the Rectisol® process, cooled methanol (CH ₃ OH) is used as the absorbent. The regeneration of the

Absorbent takes place by means of steam via indirect

Heat exchanger, wherein the absorbent is heated to only about 65 ° C. The steam requirement is about 1157 kg / MM scf = about 0.041 kg / Nm ³ gas to be cleaned. All types of heat exchange media can be used: air, nitrogen, steam, thermal oil, etc.

When Selexol method is used as an absorbent

Mixture of dimethyl ethers of polyethylene glycol used. The regeneration takes place with steam, whereby a direct

Contact of the absorbent with steam or an inert gas (e.g., nitrogen) is necessary.

With the method according to the invention, top gas from a blast furnace, in particular from an oxygen blast furnace with top gas recirculation, which is operated predominantly with oxygen instead of hot blast, can be purified of CO ₂ . The process according to the invention is best used in the case of exhaust gases from smelting reduction plants for C0 ₂ purification of at least one of the following exhaust gases:

- Exhaust gas (so-called excess gas) from a

Smelting ergaser,

Exhaust gas from at least one reduction reactor,

- Exhaust gas (so-called top gas) from at least one

Fixed bed reactor for preheating and reducing iron oxides and / or iron briquettes.

To reduce the reducing components of the gas after CO ₂ removal for the production of pig iron or

Making better use of synthesis gas production, it can be provided that at least part of the purified exhaust gas is used again as a reducing gas for the production of pig iron.

The energy necessary for the regeneration of the absorbent can be generated by passing hot air from the air separation plant into a heat exchanger for heating and regenerating the absorbent. For example, hot air may be used from the main air compressor and / or the booster air compressor.

The heat from the air separation plant can also be obtained by means of a heat transfer medium (e.g., water vapor) supplied by hot air from the air separation plant (from the

Main air compressor and / or the booster air compressor) is heated, for the regeneration of the absorbent for

In a device according to the invention, a system for removing CO ₂ by means of chemical and / or physical absorption is provided, wherein the plant part for the regeneration of the absorbent is connected to an air separation plant that the heat generated therein can be used at least partially for the regeneration of the absorbent.

In particular, a line may be provided for the blast furnace process, with which top gas from a blast furnace, in particular from an oxygen blast furnace with

Top gas recirculation, in the plant for the removal of CO ₂ by means of chemical and / or physical absorption

can be directed.

In a smelting reduction process, at least one line would then be provided in accordance with which exhaust gas from a smelting reduction plant can be conducted into the CO ₂ removal plant by means of chemical and / or physical absorption.

At least one of these lines may be connected to at least one of the following devices:

with a melter gasifier,

with one or more reduction reactors,

- With a fixed bed reactor for preheating and / or reduction of iron oxides and / or iron briquettes.

A further embodiment consists in that a line is provided, with which at least a part of the purified exhaust gas can be redirected back to the pig iron production as reducing gas.

Furthermore, at least one line can be provided, with the hot air from the air separation plant, in particular from the main air compressor and / or the booster air compressor, in a heat exchanger for heating and regeneration of

Absorbent is passed.

The invention is explained in more detail below with reference to the exemplary and schematic figures. Fig. 1 shows a phase diagram of CO ₂ .

Fig. 2 shows the relationship between impurities of gases and the compaction stations necessary for the transport of liquefied gases.

Fig. 3 shows the connection according to the invention between a blast furnace and an air separation plant.

Fig. 4 shows the connection according to the invention between a plant for smelting reduction and a Luftzerlegungsanlage.

FIG. 1 shows a phase diagram of CO ₂ . On the horizontal axis the temperature is plotted in K, on the vertical axis the pressure in bar (1 bar = 10 ⁵ Pascal). The individual states of matter (solid or solid,

Liquid or liquid and gas or gaseous) are separated by lines.

The triple point is the point where solid, liquid and gaseous phases meet.

The supercritical state (supercritical fluid) is a state above the critical point in the phase diagram, which is due to the matching of the densities of liquid and liquid

Gas phase is characterized. The differences between the two states of aggregation cease to exist at this point. In Fig. 2, the relationship between impurities of gases and the compaction stations necessary for the transport of liquefied gases is shown.

On the horizontal axis, the impurities are plotted in% of the gas volume, on the vertical axis of the

Distance between the compressor stations in km.

For each contamination, a separate curve is drawn. At 10% contamination (right margin of the illustration), the smallest influence on the distance of the

Compressor stations at H ₂ S, followed by SO ₂ , CH ₄ , Ar, O ₂ , N ₂ and CO are the same, then NO ₂ , H ₂ has the biggest influence, where the curve almost goes to zero. In Fig. 3, an oxygen blast furnace 1 is shown with top gas recirculation, in which iron ore from a sinter plant 2 and coke (not shown) is supplied.

Oxygen-containing gas 3 with an oxygen content> 80% is introduced into the loop 4, as is in

Reduction gas furnace 6 heated reducing gas 5 together with cold or preheated oxygen O _{2 introduced} into the blast furnace 1, slag 7 and pig iron 8 are below

deducted. At the top of the blast furnace 1, the top or top gas 9 is removed and pre-cleaned in a dust separator or cyclone 10 and cleaned a wet scrubber 11 (or a bag filter or hot gas filter system) again. The purified top or top gas 9 can on the one hand directly as export gas 12 removed from the blast furnace system and an export gas tank 13, on the other hand it can be fed to a plant 14 for chemical absorption of CO ₂ , wherein the purified top or top gas 9 previously in a compressor 15 is compressed (to about 2-6 barg (depending on top gas pressure)) and cooled in an aftercooler 16 to about 30-60 ° C.

The system 14 for the chemical absorption of CO ₂ consists essentially of an absorber 17 and a stripper 18. Such systems are known from the prior art and will therefore be described here only in outline. In the absorber 17 to be cleaned top or top gas 9 is introduced from below, while from the top one the acidic

Constituents of the gas (essentially CO ₂ , H ₂ S)

absorbing solution, such as an amine solution, flows downwards. Here, the CO ₂ is now removed from the top or top gas and the purified gas fed back to the blast furnace 1.

The loaded absorbent is passed from above into the stripper 18. In the lower area, the absorbent liquid is heated via an indirect heat exchanger with hot air at about 250-300 ° C or steam from the air separation plant 23

charged and heated to> 100 ° C, in particular 110-120 ° C, whereby the acidic gases, in particular the CO ₂ , are released again as residual gas 20. The residual gas 20 can either after a H ₂ S cleaning 21 back into the atmosphere

be discharged and / or another compressor 22 for the liquefaction of CO _{2 are} fed to it then

to be stored underground or as a substitute for nitrogen in iron production or

To use coal gasification, such as for Charger facilities, barrier seals and selected rinsing and cooling gas consumers.

The pressure energy content of the export gas 12 can also be measured in an expansion turbine 35 (top gas pressure recovery

turbine), which in this example is arranged in front of the export gas container 13.

The heat for the regeneration of the absorbent in the stripper 18 is generated in a heat exchanger 19, which is fed by one or two hot gas streams from an air separation plant 23: a gas stream 26 comes out of the

Main air compressor 24 and has a pressure of about 4-12 bar _g , in particular of about 5 bar _g , and a temperature of about 280 ° C; a second gas flow 27 comes from the

Boosterluftkompressor 25 and has a pressure of 5 to 25 bar _g , in particular of 23 bar _g , and a temperature of about 200 ° C. Alternatively, the heat exchange of hot air to an alternative heat transfer medium (eg

Water / steam, thermal oil, nitrogen) and then carried by the heat transfer medium to the absorption liquid. The main air compressor 24 draws in ambient air having a temperature of about 20 ° C and atmospheric pressure. It consists of about 77% nitrogen, about 21% cLU S

Oxygen, about 1% from water vapor and about 0.9%

Argon.

After the main air compressor 24, the air has a temperature of about 280 ° C and a pressure of about 5.2 barg. In the heat exchanger 19, the air from the

Luftzellegungsanlage 23 cooled to about 180 ° C.

With a Luftzerlegungsanlage 23, air in their

Components are decomposed. Air is a gas mixture of nitrogen (78%), oxygen (21%), argon (0.9%) and other noble gases. First, the air is liquefied, then separated into its components by rectification. Since these methods have been known for a long time, they should be described here only in their basic features, insofar as these are essential for the invention.

In a first step, the air sucked from the environment is first compressed in the main air compressor 24 to about 5.2 barg, whereby the air is heated to about 280 ° C. This gas stream 26 or an alternative heat transfer medium is then passed according to the invention in the heat exchanger 19 of the system 14 for the chemical absorption of CO ₂ , where it heats the absorption liquid.

In addition to the main air compressor 24, a

Boosterluftkompressor 25 may be provided which further compressed a partial flow (30-60%) of the compressed air in the main compressor 24 and in the scrubbing tower 28 and adsorber 29 purified air stream 30, approximately to about 23 bar _g , whereby the air is heated to about 200 ° C. , The booster air compressor 25th

compressed air is not completely supplied immediately to the cold box 31, but at least one part 27 according to the invention first in the heat exchanger 19, where it gives off heat to heat the absorption liquid. The other part is compressed via a turbine-driven compressor 34 and then fed to the cold box 31, wherein also a part (about 3-12% of the main air quantity) of the cooled air from the cold box 31 is returned to the compressor 34 again.

In the conventional air decomposition, the in

Master air compressor 24 compressed air 26 directly one Purification supplied, in the present invention, the cooled air in the heat exchanger 19 is pre-cooled in a scrubbing tower 28 with water and freed in an adsorber 29 of impurities such as dust, carbon dioxide, water vapor and hydrocarbons.

The thus purified air stream 30 is then fed to the so-called cold box 31, a heat exchanger in which the air flow 30 by colder air 32 from the

Rectification column 33 is cooled further. Because only by the compression in the main air compressor 24 and the pre-cooling in the scrubbing tower 28 is not yet in temperature ranges in which the air is liquid (-191 to -193 ° C). For this purpose, already relaxed gas streams, such as nitrogen 32 from rectification column 33, must be used to cool the compressed purified air 30. This air 30 thereby reaches a temperature of about -180 ° C. When subsequently relaxing in an expansion valve or in a

Expansion turbine 34 finally cools down and liquefies partially.

The liquefied air is sent to the rectification column 33, where the decomposition of the liquefied air uses the different boiling points of its components. This is the same principle as in alcohol distillation. Since the boiling points are relatively close to each other (oxygen -183 ° C, nitrogen

-196 ° C), the distillation must be carried out in a multi-stage process in this rectification column 33: The liquid air trickles over a number of sieve trays in the

Counterflow to the non-liquefied, rising air down. The liquid is stowed on the sieve plates and flowed through by the ascending vapor bubbles. From the gas stream, especially the higher boiling liquefies

Oxygen, while from the liquid drops preferably evaporates the lower boiling nitrogen. On the cold head of the Rectification column 33 therefore accumulates gaseous

Nitrogen 32 and on warmer soil liquid oxygen 36.

After the first stage of rectification, the gases are not yet pure enough. For this reason, the liquid oxygen 36 is at least partially re-evaporated in the cold box 31, the gaseous nitrogen liquefied and both returned to the rectification column 33, where the above-described operation is repeated until the desired purity is achieved.

A portion of the liquid oxygen 36 is withdrawn and stored, as is a portion of the liquid nitrogen 45.

After passing through the cold box 31 is taken:

- gaseous nitrogen medium pressure (about 11 barg), MP GAN, which previously in a compressor on

is compressed

- gaseous oxygen medium pressure (about 9 barg), MP GOX,

high pressure gaseous oxygen, HP GOX,

gaseous nitrogen of low pressure, LP GAN.

A portion of the waste nitrogen 32 from the rectification column 33 is fed to a nitrogen cooling tower 46, which is cooled by a cooling unit 65. The remaining part of the non-purified nitrogen 32 from the rectification column 33 is supplied to a preheater 66 and the

Regeneration of the adsorber 29 used. The hot air from the main air compressor 24, which has given off the heat in the heat exchanger 19 to the absorption liquid, is first cooled and further cooled in a washing tower 28, to further reduce the water vapor content and unwanted gas components. After the adsorber 29 for H ₂ O / CO ₂ removal of the purified air stream 30 is passed to the cold box 31 and on to the rectification column 33. Fig. 4 shows the connection according to the invention between a plant for smelting reduction and a Luftzerlegungsanlage 23. The Luftzellegungsanlage 23 is the same structure as those of FIG. 3, as well as the plant 14 for the chemical absorption of C0 ₂ .

The unit designed as a Finex plant for smelting reduction has in this example four reduction reactors 37-40, which are formed as fluidized bed reactors and are charged with fine ore. Fine ore and additives 41 are supplied to the ore drying 42 and from there first to the fourth reactor 37, then they get into the third 38, the second 39 and finally the first reduction reactor 40. Instead of four fluidized bed reactors 37-40 but only three may be present ,

In countercurrent to the fine ore, the reducing gas 43 is guided. It is introduced at the bottom of the first reduction reactor 40 and exits at its top. Before it enters from below into the second reduction reactor 39, it can still with

Oxygen O2 are heated, as well between the second 39 and third 38 reduction reactor. That from the fourth

Reduction reactor 37 exiting exhaust 44 is in a

Wet scrubber 47 cleaned and as export gas 12 on

used. A partial flow of the exhaust gas 44 is - according to the invention - the absorber 17 for CC> 2 removal

forwarded.

The reducing gas 43 is produced in a melter gasifier 48, in the one hand coal in the form of lumpy

Coal 49 and coal in powder form 50 - this is supplied together with oxygen O2 - in the other hand, the pre-reduced in the reduction reactors 37-40 and in the

Iron briquetting 51 is added in hot condition to iron briquettes (English: HCl Hot Compacted Iron) shaped iron ore. The iron briquettes arrive via a

Hot conveying system 52 in a storage container 53, as Fixed bed reactor is formed, where the iron briquettes are optionally preheated and reduced with coarse purified gas generator 54 from the melter gasifier 48. Cold iron briquettes and / or iron oxides (eg in the form of pellets or lump) 63 can also be added here.

Subsequently, the iron briquettes or oxides are charged from above into the melter gasifier 48. Low reduced iron (LRI) 67 may also be withdrawn from iron briquetting 51.

The coal in the melter gasifier 48 is gasified, resulting in a gas mixture consisting mainly of CO and H ₂ , and withdrawn as a reducing gas (generator gas) 54 and a

Partial flow as reducing gas 43 the reduction reactors 37-40 is fed.

The hot metal melted in the melter gasifier 48 and the slag are withdrawn, see arrow 56. The generator gas 54 withdrawn from the melter gasifier 48 is first passed into a separator 57 in order to communicate with

remove the dust and dust

Dust burner in the melter gasifier 48 due. A portion of the coarse dust purified gas generator 54 is further cleaned by wet scrubber 58 and as

Excess gas 59 taken from the Finex plant and - according to the invention - the absorber 17 of Appendix 14 to

chemical absorption of CO ₂ supplied.

Another portion of the purified generator gas 54 is also further purified in a wet scrubber 60, for

Cooling fed to a gas compressor 61 and then fed after mixing with the removed from the absorber 17, liberated from CO ₂ product gas 62, again the generator gas 54 after the melter gasifier 48 for cooling. As a result of this recycling of the CO ₂ -free gas 62, the reducing fractions contained therein can still be utilized for the Finex process and, on the other hand, the required Cooling of the hot generator gas 54 of about 1050 ° C to 700-870 ° C are ensured.

This from the storage facility 53, where the iron briquettes or

Iron oxides with dedusted and cooled generator gas 54 are heated and reduced from the melter gasifier 48, emerging top gas 55 is purified in a wet scrubber 64 and then also supplied to the absorber 17 for removing CO ₂ .

The residual gas 20 after the stripper 18 can be released into the atmosphere again wholly or in part after H ₂ S cleaning 21 or completely or partially - after compression by means of compressor 22 - a C0 ₂ ~ storage are supplied.

The export gas 12 may be in an export gas container 13

be cached. An optional

Expansion turbine 35 serves to exploit the energy contained in the export gas 12.

The stripper 18 is supplied with preheated absorption liquid, which via at least one heat exchanger 19 with the release of the heat of the hot compressed air after the

Main air compressor 24 or Boosterluftkompressor 25 or is heated by means of heat transfer medium. The heat exchanger 19 is - as in Fig. 3 - of at least one

Hot gas stream from an air separation plant 23 fed: a gas stream 26 comes from the main air compressor 24 and has a pressure of 5 to 12 bar _g , in particular of about 5.2 bar _g , and a temperature of about 280 ° C; a second

Gas stream 27 comes from the booster air compressor 25 and has a pressure of 20 to 25 bar _g , in particular of 23 bar _g , and a temperature of about 200 ° C. After the booster air compressor 25, the compressed air is compressed up to 36 bar _g by a turbine driven compressor 34. Reference sign list

1 blast furnace

2 sinter plant

3 oxygen-containing gas

4 ring line

5 reducing gas

6 reduction gas furnace

7 slag

8 pig iron

9 top or topping gas

10 dust collector or cyclone

11 wet scrubbers

12 export gas

13 export gas containers

14 plant for the chemical absorption of CO ₂

15 compressor

16 aftercoolers

17 absorbers

18 strippers

19 heat exchangers

20 residual gas after stripper 18

21 H ₂ S cleaning

22 compressors for the liquefaction of CO ₂

23 air separation plants

24 main air compressor

25 booster air compressor

26 Gas flow from main air compressor 24

27 Gas flow from booster air compressor 25

28 wash tower

29 Adsorber

30 cleaned air stream

31 cold box

32 waste nitrogen from rectification column 33

33 rectification column 34 turbine-driven compressor

35 relaxation turbine

36 liquid oxygen

37 Fourth reduction reactor

38 Third reduction reactor

39 Second reduction reactor

40 First reduction reactor

41 fine ore and additives

42 ore drying

43 reducing gas

44 waste gas from reduction reactors 37-40

45 liquid nitrogen

46 nitrogen cooling tower

47 Wet scrubber for exhaust gas 44

48 melter gasifier

49 lumpy coal

50 coal in powder form

51 iron briquetting (HCI plant)

52 hot conveyor system

53 designed as a fixed bed reactor storage container for

Preheating and reduction of iron oxides and / or iron briquettes

54 generator gas from melter gasifier 48

55 top gas from wet scrubber 64

56 hot metal and slag

57 separators for fine ore

58 wet scrubbers

59 surplus gas

60 wet scrubbers

61 gas compressor

62 gas released from CO ₂ from absorber 17

63 cold iron briquettes or oxide materials

64 wet scrubbers

65 cooling unit

66 preheating device

67 Low Iron (LRI)

Claims

claims

1. A method for removing CO ₂ from exhaust gases (12, 44, 55, 59), such as exhaust gases from plants for pig iron production or exhaust gases from synthesis gas plants, characterized in that the CO ₂ by means of chemical and / or physical absorption (14) is removed , where the heat to

Regeneration of the absorbent is at least partially obtained from an air separation plant (23).

2. The method according to claim 1, characterized in that is used as an absorbent potassium carbonate.

3. The method according to claim 1 or 2, characterized

characterized in that it comprises an amine wash.

4. The method according to claim 3, characterized in that primary amines, such as methylamine, monoethanolamine (MEA) and / or diglycolamine (DGA) are used.

5. The method according to claim 3 or 4, characterized

in that secondary amines, such as diethanolamine (DEA) and / or diisopropanolamine (DIPA), are used.

6. The method of claim 3, 4 or 5, characterized

in that tertiary amines, such as triethanolamine (TEA) and / or methyldiethanolamine (MDEA), are used.

7. The method according to any one of claims 1 to 6, characterized

characterized in that top gas (9) from a blast furnace, in particular from an oxygen blast furnace (1) with

Top gas recirculation, is purified by CO ₂ .

8. The method according to any one of claims 1 to 7, characterized

characterized in that exhaust gas (44, 55, 59) from a

Smelting plant is cleaned.

9. The method according to claim 8, characterized in that at least one of the following exhaust gases is purified:

Exhaust gas (59) from a melter gasifier (48),

Exhaust gas (44) from at least one reduction reactor (37-40),

- Exhaust (55) from at least one fixed bed reactor (53) for preheating and / or reduction of iron oxides and / or iron briquettes.

10. The method according to any one of claims 1 to 9, characterized

characterized in that at least part of the purified

Exhaust gas (62) again as a reducing gas to

Pig iron production is used.

11. The method according to any one of claims 1 to 10, characterized in that hot air or a

Heat transfer medium from the Luftzerlegungsanlage (23) is passed into a heat exchanger (19) for heating and regeneration of the absorbent.

12. The method according to any one of claims 1 to 11, characterized in that hot air from the

Main air compressor (24) and / or the Boosterluftkompressor (25) or the waste heat is used by means of heat transfer medium.

13. The method according to any one of claims 1 to 12, characterized

characterized in that the recovered CO ₂ rich gas from the C0 ₂ ~ removal process as substitute gas in the

Iron production process or for processing and

Storage of CO ₂ is used.

14. Device for carrying out the method according to one of claims 1 to 13, characterized in that a system (14) for the removal of CO ₂ by means of

chemical and / or physical absorption is provided, wherein the plant part (18) for the regeneration of the absorbent so connected to an air separation plant (23) that the heat generated therein at least partially for the regeneration of the

Absorbent can be used.

15. The apparatus according to claim 14, characterized in that a line is provided with which top gas (9) from a blast furnace, in particular from a

Oxygen furnace (1) with Topgasrückführung, in the

Plant (14) can be passed to remove CO ₂ by means of chemical and / or physical absorption.

16. The apparatus according to claim 14, characterized in that at least one line is provided with which exhaust gas (44, 55, 59) from a smelting reduction plant in the system (14) for the removal of CO _{2 can be conducted} by means of chemical and / or physical absorption.

17. The device according to claim 16, characterized in that at least one of these lines is connected to at least one of the following devices:

with a melter gasifier (48),

with one or more reduction reactors (37-40),

- With a fixed bed reactor (53) for preheating and reduction of iron oxides and / or iron briquettes.

18. Device according to one of claims 14 to 17, characterized in that a line is provided, with which at least a part (62) of the purified exhaust gas can be routed back to the pig iron production again as a reducing gas.

19. Device according to one of claims 14 to 18, characterized in that at least one line is provided, with the hot air (26, 27) or another

20. The apparatus according to claim 19, characterized in that at least one line is provided with the hot air (26, 27) or another heat transfer medium from the main air compressor (24) and / or the Booster air compressor (25) can be passed into the heat exchanger (19).

21. Device according to one of claims 14 to 20, characterized in that the system (14) for the removal of CO ₂ by means of chemical and / or physical absorption so with a plant for pig iron production and / or a plant for processing and storage of CO ₂

connected, that the recovered CO ₂ rich gas can be used as a substitute gas in the iron production process and / or for the treatment and storage of CO ₂ .