WO2011144401A1

WO2011144401A1 - Method and device for regulating the temperature of process gases from plants for raw iron production for use in an expansion turbine

Info

Publication number: WO2011144401A1
Application number: PCT/EP2011/056105
Authority: WO
Inventors: Robert Millner; Kurt Wieder
Original assignee: Siemens Vai Metals Technologies Gmbh
Priority date: 2010-05-20
Filing date: 2011-04-18
Publication date: 2011-11-24
Also published as: KR20130087401A; KR101792486B1; AT509224B1; CN102985567A; AT509224A4; CN102985567B

Abstract

Presented is a method and a device for regulating the temperature of process gases (12) from plants for raw iron production for use in an expansion turbine (34), characterized in that the inlet temperature of the process gas (12) as it enters the expansion turbine (34) is adjusted such that it does not fall below a minimum inlet temperature at which condensation occurs in the expansion turbine, and/or in that the process gas (12) is cooled such that the process gas emerging from the expansion turbine, as it enters a low-pressure gas accumulator (13), does not exceed a maximum admissible inlet temperature for the latter. In this way, at least either cooling of the export gas to or below the condensation temperature as it exits the expansion turbine can be prevented, or for the introduction of the export gas into a low-pressure gas accumulator, the use of export gas coolers can be avoided.

Description

Method and device for controlling the temperature of process gases from pig iron production plants for use in an expansion turbine

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 the carbon from the coke, the necessary heat for the reaction and carbon monoxide or hydrogen, which is a significant part of the 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 top or top gas recirculation, in the gasification of coke or coal oxygen-containing gas with more than 80% oxygen content (0 ₂ ) in the blast furnace

blown.

For the emerging from the blast furnace gas, the so-called Top ^¬ or blast furnace gas purification must be provided (eg Dust collectors 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 C02 ~ removal, according to the prior art usually by 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-stage 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® process corresponds to the

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

The process gas, which is withdrawn from the process of pig iron production or synthesis gas production, because it can no longer be used there, is often referred to as "export gas." It is used in particular as a name for that part of the top gas, which deducted from the process of pig iron production , usually cooled, such as in a waste heat boiler, and usually also dedusted, especially dry

Dusted, will.

After dry dedusting and heat extraction from the top gas of a COREX® plant, the gas has a temperature from about 150-250 ° C and a pressure of typically 3 bar _g .

The top gas of a COREX® system has after the

Dry dedusting and heat extraction in approximately the following composition:

CO 38.5 vol%

C0 ₂ 31, 6 vol%

H ₂ 15.3 vol%

H ₂ 0 11.1 vol%

CH ₄ 1.5 vol%

N ₂ 2.0 vol%

The export gas can be compressed, such as by means of one or two-stage centrifugal compressors, and then cooled to produce e.g. be used as fuel gas continue to be used or stored.

However, it is the energy content of the export gas, the pressure and heat energy, in a so-called expansion or expansion turbine (English: Topgas Recovery Turbine, short TRT) are used for power generation. The export gas after the expansion turbine has a lower pressure and a lower temperature than before the expansion turbine.

For a COREX® C-3000 plant with an export gas production of about 327,000 Nm ³ / h, a dry dedusting, a

Expansion turbine with an efficiency of 85 "6 and an associated generator with an efficiency of 97% result - with an export gas composition as above - at the inlet temperatures and pressures given below when entering the expansion turbine, the following

Exit temperatures and pressures for the export gas at the exit from the expansion turbine and the generated electric power and the condensate accumulating in the expansion turbine:

Due to temperature losses of the export gas lines, the actual temperatures may differ from the above and below mentioned temperatures. The

Operating parameters of the expansion turbine will also vary depending on the gas composition of the export gas and therefore on the parameters mentioned above

deviate. If a wet cleaning is carried out instead of dry dedusting for the top gas of a COREX® plant, the following typical values result:

If the inlet temperature of the export gas when entering the expansion turbine falls below a temperature of about 150 ° C, more precisely below 146, 5 ° C, then falls

Exit temperature of the export gas exiting the expansion turbine below the condensation temperature of 51 ° C. This leads to drip within the

Expansion turbine and caking by dust and, where appropriate, for the condensation of polycyclic

aromatic hydrocarbons, short PAK. The result is that the life of the expansion turbine is reduced and the expansion turbine every 3-4 months for maintenance, namely to remove the deposits, must be turned off. For each expansion turbine can depend on the

Water content of the export gas that minimum

Inlet temperature are determined at which just does not take place condensation in the expansion turbine. If the export gas, when entering the expansion turbine, has a lower temperature than this minimum inlet temperature, condensation will occur.

On the other hand, if the inlet temperature of the export gas rises to more than 175 ° C when entering the expansion turbine, then the outlet temperature of the

Export gas to over 75 ° C. Since the export gas to

In this case, the temperature of the export gas before entering into the low-pressure gas storage must be introduced equalization of its amount and its calorific value

Low-pressure gas storage can be reduced by direct or indirect cooling. If you join one

Low-pressure gas storage, the export gas should therefore not exceed a maximum export gas temperature.

However, the use of export gas coolers for this purpose has the following disadvantages:

Investment costs for coolers, pumps, pipelines, basins, recooling;

- Power consumption for pumps and recooling as well

possibly water consumption;

- environmental problems in the case of direct coolers, as the direct contact of the cooling water with the export gas can release pollutants into the environment;

- Caking in the case of indirect coolers. It is therefore an object of the invention, at least either the cooling of the export gas at the exit from the

Relaxation turbine on or under the

Condensation to prevent condensation or for the introduction of the export gas in a low-pressure gas storage the use of export gas coolers in continuous operation

avoid.

The object is achieved by a method according to claim 1, in that the inlet temperature of the process gas is set on entering the expansion turbine so that it does not fall below a minimum inlet temperature at which condensation occurs in the expansion turbine, and / or that the process gas is cooled such that the process gas leaving the expansion turbine does not exceed a maximum inlet temperature permissible for it when entering a low-pressure gas storage, by at least one of the following measures:

- Regulation of the process gas temperature by controlling a waste heat recovery system, in particular a

Heat recovery steam generator, which flows through the process gas before entering the expansion turbine,

- Regulation of the process gas temperature by controlling the amount of process gas, which is passed to the waste heat recovery system, in particular the heat recovery steam generator, passed over cooled,

Admixing cooled, pressurized further process gas to the process gas upstream of the expansion turbine,

- Injecting water into the process gas (causing

however, the dew point temperatures are shifted

would)

- Adding cold residual gas from a plant for CO ₂ removal to the process gas after the expansion turbine.

There are thus three variants of the invention: A) The inlet temperature of the process gas entering the expansion turbine is adjusted so that it does not fall below a minimum inlet temperature at which condensation occurs in the expansion turbine. The process gas is thus either not or usually by the

Waste heat recovery system only cooled so far that no components of the process gas condense in the expansion turbine. The waste heat recovery system as part of the plant for pig iron production anyway available to the heat of the hot process gas (about 350-450 ° C) for the

Steam generation, to use for warming up other process gases or another heat transfer medium (for example nitrogen or thermal oil). In the example of the COREX® plant mentioned in the introduction, this means that, due to the regulation according to the invention, the inlet temperature of the process gas must not fall below 146.5 ° C.

But it may be that by this measure, the process gas after the expansion turbine too hot for the

Low-pressure gas storage is.

B) The process gas is cooled so far that the out of the

Expansion turbine exiting process gas when entering a low-pressure gas storage does not exceed a permissible maximum export gas temperature for this. If necessary, condensation is accepted in the expansion turbine. The process gas is either already before

Relaxation turbine cooled, for example by cooling the gas in the waste heat recovery system and / or by admixing cooled further process gas before the expansion turbine and / or by injecting water before the

Expansion turbine, and / or by injecting water after the expansion turbine and / or by mixing cold residual gas from a plant for C02 ~ removal after the expansion turbine. When cooling before the Expansion turbine can then come to condensation in the expansion turbine.

In the example of the COREX® system mentioned above, this measure means that the inlet temperature of the process gas in the expansion turbine is only controlled to below 175 ° C. Or that the inlet temperature of the process gas is not regulated in the expansion turbine, but the emerging from the expansion turbine process gas is cooled to below 75 ° C.

C) The inlet temperature of the process gas entering the expansion turbine is adjusted so that it does not fall below a minimum inlet temperature at which condensation occurs in the expansion turbine and

At the same time it is ensured that the process gas does not exceed a maximum export gas temperature permissible for this when entering a low-pressure gas storage tank. In this measure, both the condensation in the

Expansion turbine avoided as well as a sufficiently low process gas temperature when entering the

Low-pressure gas storage ensured. This can be done only by measures in front of the expansion turbine, so

For example, only by a corresponding regulation of the waste heat recovery system, if necessary, under

Inclusion of the uncooled passed by

Process gas. In addition, however, cooled further process gas can be introduced or water can be injected.

In the example of the COREX® plant mentioned in the introduction, this can be realized in such a way that the inlet temperature of the process gas in the expansion turbine is controlled to a value in the range between about 150 ° C to 175 ° C.

But it can also be cooled by the expansion turbine in this third method of the invention, the exhaust gas by injecting water and / or by adding cold residual gas from a C0 ₂ removal unit.

When injecting water into the process gas, which usually takes place before the expansion turbine, it should be noted that this increases the condensation temperature or dew point temperature and thus the minimum

Inlet temperature at which condensation occurs in the expansion turbine.

The waste heat recovery system does not have to be as

Heat recovery steam generator be formed. Instead, other heat exchangers can be used. For example, one or more gas-gas heat exchangers

be used, for example, to warm up another

Process gases of the plant for the production of pig iron. Or other heat transfer media can be warmed up, such as

Nitrogen or thermal oil to be used indirectly for heating other media. Of course, combinations of different waste heat recovery systems are possible.

As a rule, as by the expansion turbine

Process gas used an exhaust gas used, which was previously removed from the plant for pig iron production and not after the expansion turbine back into the plant to

Pig iron production is led back. This is called "export gas", because it is just from the plant to

Pig iron production is finally deducted. The plant for the production of pig iron includes here next blast furnace or

Melt carburetor and reduction shafts or reactors and the filter systems (hot gas filter, bag filter,

Cyclones) and any waste heat boilers for the cooling of

Export gas as well as any plant for the removal of CO ₂ . This process or export gas can now top gas from a blast furnace, in particular from an oxygen blast furnace,

contain .

But it may also contain exhaust gas from a smelting reduction plant, in particular

Exhaust gas from a melter gasifier,

Exhaust gas from at least one reduction reactor,

Exhaust gas from at least one fixed bed reactor, in particular for preheating and / or reduction of iron oxides and / or

Iron briquettes.

For example, in the COREX® process, a melter gasifier and at least one fixed bed reactor are used to reduce

Iron carriers for use, in the FINEX® process

Meltdown gasifier and a plurality of successively connected, designed as fluidized bed reactors reduction reactors.

The process or export gas from a smelting reduction plant used for the invention can, of course, be fed from several sources of the smelting reduction plant. In general, the partial flows of the individual

Plant parts (melter gasifier, reduction reactor,

Fixed bed reactor) vary over time.

The mentioned process gases from the plant to

Pig iron production (blast furnace or smelting reduction plant) can also be removed in other ways from the plant and cooled and mixed as cooled, under pressure further process gas the so-called export gas before the expansion turbine for the purpose of cooling, which are also mixed for the purpose of heating could, for example, if the export or process gas was cooled down too much by the waste heat recovery system and these gas streams were previously cleaned while hot. It makes sense to use that cooled process gas that is obtained in the plant for pig iron anyway in the production of pig iron, such as the purified and cooled reducing gas from a melter gasifier, which has not been passed to the reduction reactor (excess gas).

To avoid condensation in the expansion turbine can be provided that the inlet temperature of the process gas is not below the minimum inlet temperature of about 145 ° C when entering the expansion turbine. To both condensation and too high

Preventing entry of export or process gas into the low-pressure gas storage is best

provided that the inlet temperature of the process gas is set to a value in the range of 150-175 ° C when entering the expansion turbine. This results in an outlet temperature of the process gas from the

Relaxation turbine in the range of 55-75 ° C, a further cooling after the expansion turbine is then no longer necessary.

The export or process gas can also or additionally

Alternatively, even before or after the expansion turbine to be cooled so far that the maximum inlet temperature in the low-pressure gas storage of about 80 ° C not

is exceeded.

In order to protect the expansion turbine from abrasion and contamination, it can be provided that at least part of the process gas is dry-dedusted in front of the expansion turbine. As a rule, the dry dedusting takes place anyway in the plant for pig iron production, it must then be installed no own dry dedusting for the expansion turbine. The dry dedusting is typically done by means of bag filter, the waste heat recovery system downstream or by means of ceramic hot gas filters, which are connected upstream of the waste heat recovery system.

In addition, hot gas cyclones or so-called "dust catchers" (dust collectors) can be used, whereby these serve for the coarse dedusting and the plants for

Fine dedusting (bag filter, hot gas filter) are connected upstream. Dry dust removal has the advantage over wet processes that much less energy is extracted from the process gas, which is to be used in the expansion turbine.

A corresponding device for carrying out the

The method according to the invention can be embodied such that the plant for producing pig iron with at least one first process gas line for introducing process gas into a

Relaxation turbine is connected, and the

Relaxation turbine is connected by a second process gas line with a low-pressure gas storage for process gas, wherein additionally at least one of the following

Facilities is provided:

a first control device and one before the

Expansion turbine, especially in the plant for

Pig iron production, arranged waste heat recovery plant, in particular a heat recovery steam generator plant, wherein the first control device for the waste heat recovery plant is used to control the process gas temperature,

a second control device and a bypass line, wherein the second control device for regulating the amount of process gas, which is passed to the waste heat recovery system, in particular the heat recovery steam generator system, bypassed by means of a bypass line, serves,

a third control device, with which the amount of cooled, pressurized further process gas from the plant for the production of pig iron, which in the first Process gas line is conducted, regulated,

a fourth control device with which the amount of water which can be injected into the first or second process gas line by means of an injection device is regulated,

- A fifth control device with which the amount of cold residual gas from a plant for C02 ~ removal is mixed by means of a residual gas line in the second process gas line to the process gas, is regulated.

If several of these five mentioned control devices are present, they are linked to a central control or one of the control devices, such as the first, takes over the calculation of the setpoints and control values and control of the other control devices.

If the export gas from a blast furnace in the

Relaxation turbine are passed, at least one line is provided with which top gas from a blast furnace, in particular from an oxygen blast furnace with

Topgas return, in the first process gas line can be passed.

If the export gas to be passed from a smelting reduction plant in the expansion turbine, at least one line is provided, with which exhaust gas from a

Smelting reduction plant can be directed into the first process gas line. It is then provided that

at least one of these lines is connected to at least one of the following devices:

with a melter gasifier,

with one or more reduction reactors,

- With a fixed bed reactor, in particular for preheating and / or reduction of iron oxides and / or iron briquettes. Before the expansion turbine, a system for dry dedusting of the process gas can be arranged. This serves to protect the expansion turbine from contamination and abrasion.

The invention is explained in more detail below with reference to the exemplary and schematic figures.

Fig. 1 shows a COREX® system with bag filters for

Dedusting and downstream expansion turbine,

Fig. 2 shows a COREX® system with ceramic filters for

Dedusting and downstream expansion turbine,

Fig. 3 shows a FINEX® system with bag filters for

Dedusting and downstream expansion turbine,

Fig. 4 shows a FINEX® plant with ceramic filters for

Dedusting and downstream expansion turbine,

Fig. 5 shows an oxygen blast furnace with bag filters for dedusting and downstream expansion turbine.

6 shows an oxygen blast furnace with ceramic filters for dedusting and downstream expansion turbine.

In Fig. 1, a COREX® system is shown. It has, in this example, a reduction shaft 17, which is designed as a fixed bed reactor and is charged with lump, pellets, sinter and additives, see reference number 18.

In countercurrent to the lump etc. 18, the reducing gas 19 is guided. It is introduced in the lower region of the reduction shaft 17 and exits at its upper side as a top gas 22. The heat of the top gas 22 from the reduction shaft 17 is used in a waste heat boiler 21 for generating steam, the resulting low-pressure steam can a stripper a - not shown here - Appendix 14 for chemical Absorption of CO _{2 are} supplied. Before entering the waste heat boiler 21, the top gas 22 can be freed of coarse dust in a dust separator or cyclone 23. Of the

separated dust 24 from the cyclone 23 can in the

Melt carburetor 48 are returned.

The emerging from the waste heat boiler 21 top gas is further purified in a bag filter 30 and fed as export gas 12 of the expansion turbine 34.

The reducing gas 19 for the reduction shaft 17 is produced in a melter gasifier 48 into which coal in the form of lumpy coal 49 and optionally coal in powder form is fed, into which the iron ore prereduced in the reduction shaft 17 is added. With the lumpy coal 49 can also fine ore 47, which is too fine for the reduction shaft 17, are introduced.

The coal in the melter gasifier 48 is gasified, it produces a gas mixture consisting mainly of CO and H ₂ , and withdrawn as a top gas (generator gas) 54 and a partial flow as reducing gas 19 is fed to the reduction shaft 17, after it in a separator 59, the Here is designed as a hot gas cyclone, was cleaned of dust and fine ore. The dust deposited here and the deposited fine ore 25 are returned to the melter gasifier 48.

The hot metal melted in the melter gasifier 48 and the slag are withdrawn, see arrow 58.

The top gas 54 withdrawn from the melter gasifier 48 is first passed into a separator 59 to separate with discharged dust and the dust 25 - possibly via dust burner - returned to the melter gasifier 48. Part of the top dust 54 cleaned by the coarse dust is further purified by means of wet scrubber 26 and as excess gas 27 taken from the COREX® plant and - according to the invention - the export gas 12 fed to the expansion turbine 34. Alternatively or additionally, a portion of the excess gas 27 for cooling the export gas 12 after this

Expansion turbine 34 are mixed.

A portion of the purified top or generator gas 54 after the wet scrubber 26 is supplied to a gas compressor 63 for cooling and then as the cooling gas 28 back to the top or

Generator gas 54 fed to the melter gasifier 48 for cooling. Through this repatriation, the in it

can still be exploited for the COREX® process and on the other hand, the

required cooling of the hot top or generator gas 54 of about 1050 ° C to 700-870 ° C are ensured.

Between the cyclone 23 and the waste heat boiler 21, water is injected into the top gas 22 with a first injection device 29 in order to cool it. After the waste heat boiler 21, the top gas 22 enters the bag filter, where the fine dust is separated. After the bag filter begins the first process gas line 31 for the export gas 12, which in the

Expansion turbine 34 ends. The second process gas line 32 starts at the expansion turbine 34 and ends at

Export gas tank 13, the low-pressure gas storage

is trained.

In the first process gas line first opens the line for the excess gas 27, then a second

Injector 33 is provided to further cool the export gas 12.

By means of a bypass line 36 Topgas 22 can be passed uncooled to the waste heat boiler 21 over.

In a first control device 45, the processes are controlled in the waste heat boiler 21, but it is also with the connected to other control devices according to the invention, as the dashed lines show:

with a second control device, here in the form of a controllable valve 46, with which the bypass line 36 can be opened or closed completely or partially,

- With a third control device, here in the form of a controllable valve 57, for the line for the excess gas 27 and

- With a fourth control device, here in the form of a controllable valve 56 for the second injector 33rd

Furthermore, the first control device 45 is connected to a first temperature sensor 67, the temperature of the export gas 12 directly before entering the

Relaxation turbine 34 measures, with a second

Temperature sensor 68, which measures the temperature of the export gas 12 immediately after exiting the expansion turbine 34, and a third temperature sensor 69, the

Difference of the measured values of the first and the second

Temperature sensor measures.

Based on the measured temperature values, the setpoint values are then determined and with the aid of the abovementioned

Control devices set.

Excess export gas can be conveyed before the expansion turbine 34 through a first line 70 and after the expansion turbine 34 through a second line 71 to a flare system 72 and flared there.

A portion of the export gas 12 can be passed past a pressure measurement with a pressure sensor 73 by means of a bypass line 74 for the expansion turbine 34 at this. This is in particular for startup and shutdown of the

Relaxation turbine required, but can also in the Normal operation can be used to control partial gas quantities.

For safety, an export gas cooler 75 can still be arranged after the expansion turbine 34, by which the gas mixture of export gas 12 after the expansion turbine 34 and excess gas 27, which was introduced after the expansion turbine 34, is completely or partially cooled. The part to be cooled is removed from the second process gas line 32, passed through the export gas cooler 75 and returned to the second process gas line 32. For cooling, cold water 76 is used. If the regulation according to the invention fills in, it can be ensured by means of the export gas cooler 75 that the export gas 12 is not too high

Temperature in the export gas tank 13 occurs.

In Fig. 2 as well as in Fig. 1 is a COREX® system

However, it differs from that in Fig. 1 by the filters used for dedusting.

Instead of the cyclone 23 for top gas from Fig. 1 is a

Hot gas filter 11 used with ceramic filter elements. In hot gas filters are hot gas filter elements predominantly in the form of porous candles made of ceramic, fiber ceramics or

Sintered metal used. The on the filter candles

accumulated dust can be cleaned from the filter cartridges through a backwashing device, which is typically operated with nitrogen 2.

The separated in the hot gas filter 11 dust may alternatively be fed back to the melter gasifier 48.

A further embodiment variant is that in front of the hot gas filter 11, a cyclone 23, more precisely, a

Hot gas cyclone is arranged. As a result, the dust content of the top gas 22 can be further reduced. In FIG. 3, instead of the COREX® system of FIGS. 1 and 2, a FINEX® system is used.

The export gas 12 is fed to an expansion turbine 34 and then cached again in a formed as a low-pressure gas storage export gas container 13. It can then be a raw material drying or a

Power plant can be supplied as fuel, see

Reference numeral 35.

The FINEX® system has four in this example

Reduction Reactors 37-40, which as

Fluidized bed reactors are formed and charged with fine ore. Fine ore and additives 41 are the

Erztrocknung 42 supplied and from there first to the fourth reactor 37, they then 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 O _{2 are} heated, as well between the second 39 and third 38 reduction reactor. The heat of the exhaust gas 44 from the reduction reactors 37-40 is used in a waste heat boiler 21 for generating steam, the resulting

Low-pressure steam can the stripper of Appendix 14 to

chemical absorption of CO _{2 are} supplied.

The exiting from the fourth reduction reactor 37 exhaust 44 is cleaned after the waste heat boiler 21 in a bag filter 30. A partial flow of exiting from the bag filter 30 exhaust gas is 12 as the export gas Expansion turbine 34 supplied, another partial flow is to be used as recirculation gas 79 again in the FINEX® method. For this purpose, it is cooled in a gas cooler 77 by means of cold water 78, compressed in the recirculating gas compressor 80, cooled again in a subsequent cooler 81 and then one

Appendix 14 for the removal of CO ₂ supplied, such as by adsorption (eg pressure swing system or

Vacuum pressure exchange system) or chemical absorption.

If C0 ₂ emissions to the atmosphere are to be reduced in the production of pig iron, this must be avoided

Exhaust gases from the pig iron production and deposited in

stored in CO ₂ Capture and Sequestration (CCS).

The residual gas stream 82 after the chemical absorption 14 mainly contains CO ₂ , a portion of the residual gas 82 can through a residual gas line 84, which opens into the second process gas line 32, the export gas 12 before entering the

Export gas containers are supplied for cooling. A

corresponding fifth control device 20 for this purpose is shown in Fig. 3.

The reducing gas 43 is in Fig. 3 in a

Melt gasifier 48 produced in the one hand coal in the form of lumpy coal 49 and coal in powder form 50 - this is supplied together with oxygen O ₂ - in the other hand, in the reduction reactors 37-40

prereduced iron ore formed into hot briquetting 51 into hot briquettes (English: HCl Hot Compacted Iron). The iron briquettes arrive via a conveyor 52 in a storage tank 53, which is designed as a fixed bed reactor, where the iron briquettes with coarse purified gas generator 54 from the melter gasifier 48 optionally preheated and reduced. Here Cold iron briquettes 65 may also be added.

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

The coal in the melter gasifier 48 is gasified, it produces 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 top gas 54 withdrawn from the melter gasifier 48 is first passed into a separator 59 to separate with discharged dust and return the dust via dust burner in the melter gasifier 48.

A portion of the top dust purified by the coarse dust is further purified by wet scrubber 60 and supplied as excess gas 61 of the CO ₂ chemical absorption unit 14, before the recycle gas compressor 80.

Another portion of the purified gas generator 54 is also in a wet scrubber 62 for cooling gas on

cleaned, fed to a gas compressor 63 for cooling and then supplied to the generator gas 54 after the melter gasifier 48 for cooling after being mixed with the recirculated gas 79 removed from the system 14, freed from CO ₂ . As a result of this recycling of the CO ₂ -fiber-free gas 79, the reducing fractions contained therein can still be exploited for the FINEX® process and, on the other hand, the

Required cooling of the hot gas generator 54

be 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 cleaned in a wet scrubber 66 and can then also the system 14 for the removal of CO _{2 are} supplied.

In the case of a chemical absorption plant for CO ₂ removal, the stripper of the plant 14 can

Low pressure steam from the waste heat boiler 21 are supplied. Preferably, in this case, the waste heat from the iron production process should be used because of the short distances between waste heat boiler and Appendix 14 to

chemical absorption of CO ₂ .

The condensate of the stripper can in this example the

Steam cycle of the waste heat boiler 21 are supplied.

The export gas 12 consists only of the exhaust gas 44 of the

Reduction Reactors 37-40.

All available in this embodiment

Control devices (first 45, second 46, fourth 56 and fifth 20) are connected to each other and their manipulated variables are specified centrally.

The operations of the second injector 33, the optional export gas cooler 75, the flare system 72, the temperature sensors 67-69, the pressure sensor 73, and the

Bypass line 74 are explained as in Fig. 1.

The plant in Fig. 4 corresponds substantially to that in Fig. 3, but in Fig. 4 that from the fourth

Reduction reactor 37 exiting exhaust 44 before the

Waste heat boiler 21 cleaned in a hot gas filter 11. A partial flow of exiting the waste heat boiler 21 exhaust gas is then as export gas 12 of the expansion turbine 34th fed, another partial flow is to be used as recirculation gas 79 again in the FINEX® method.

In Fig. 5, the invention is illustrated by means of an oxygen blast furnace. Here iron ore from a sinter plant 2 and coke (not shown) via a charging device from above into the blast furnace 1 is fed. Oxygen-containing gas 3 with an oxygen content> 80% is introduced into the loop 4, as well as coal in powder form 50. Im

Reduction gas furnace 6, reducing gas 5 is heated, wherein for the combustion of oxygen O ₂ and combustion air are supplied. Together with cold or preheated oxygen O ₂ , the heated reducing gas 5 in the blast furnace 1

brought in. Slag 7 and pig iron 8 are drawn down from the blast furnace 1. In the upper part of the blast furnace 1, the top or top gas 9 is removed and pre-cleaned in a dust separator or cyclone 10. The purified top or top gas 9 is still so hot that its energy is meaningfully used in a waste heat boiler 21 for steam generation. As with the waste heat boilers 21 of the other Fig. Again, the left circuit represents the steam cycle, the right circuit is used for heating and evaporation of condensate. For cooling the top gas 9 in front of the waste heat boiler, a first injection device 29 for water is again provided. By means of a bypass line 36, top gas 9 can again be passed uncooled around the waste heat boiler 21. The top gas 9 enters after the waste heat boiler 21 in a bag filter 30 (it could be arranged instead of a wet scrubber at this point) and is further cleaned, so that the fine dust is deposited and can be removed, see arrow at the bottom of the Bag filter 30. The purified and optionally cooled top gas 9 can on the one hand taken directly as export gas 12 from the blast furnace system and the expansion turbine 34 and then the

Export gas container 13 are supplied. On the other hand, it may be fed to a C02 removal unit 14, wherein the purified and recirculating top or top gas 9 is previously cooled in a gas cooler 77 cooled with cold water 78, followed by a compressor 15 to about 2-6 bar _{g is} compressed and cooled in an aftercooler 16 to about 30- 60 ° C. Only then is the top gas 9 to be recycled introduced into the plant 14 for CO 2 removal. The

Operation of this system has already been explained in Fig. 3. In addition, in Fig. 4 a - dashed line shown - provided with which the

recirculating top gas 9 either only on the gas cooler 77 over, only on the system 14 over or gas cooler 77 and system 14 over as fuel gas in the reduction gas furnace 6 is passed.

The CO2 purified product gas is used as reducing gas 5 either directly and / or after heating in the

Reduction gas furnace 6 fed back to the blast furnace 1. The CO2 rich residual gas 82 can discharge as in Fig. 3 directly into the atmosphere and / or just a C02 compression with

subsequent C02 storage be fed (Engl .:

Sequestration, e.g. EOR - enhanced gas recovery) and / or as a substitute for 2 in iron production: the residual gas stream consists mainly of CO2 and can therefore be used for

Charging equipment, barrier seals and selected Spül- and Kühlgasverbraucher be used.

However, part of the residual gas 82 can also be supplied to the reduction gas furnace 6 as fuel gas. Finally, a portion of the residual gas 82 through a residual gas line 84, which in the second process gas line 32 opens, are fed to the export gas 12 before entering the export gas container for cooling. A corresponding fifth control device 20 for this purpose is shown in Fig. 4.

All available in this embodiment

Bypass line 74 are explained as in Fig. 1.

The plant of Fig. 6 differs from that in Fig. 5 only by the nature of the cleaning of the top gas 9. In Fig. 6, namely the top gas 9 after the dust or

Cyclone 10 further purified in a hot gas filter 11, so that the fine dust is separated and can be removed, see arrow at the bottom of the hot gas filter 11. The purified top or top gas 9 is then passed into the waste heat boiler 21.

The export gas 12 from the export gas container 13 can - regardless of the embodiment of the invention - a combined cycle power plant or a steam power plant are fed as fuel. Reference sign list:

1 blast furnace

2 sinter plant

3 oxygen-containing gas

4 ring line

5 hot winds

6 reduction gas furnace

7 slag

8 pig iron

9 top or topping gas

10 dust collector or cyclone

11 hot gas filters

12 export gas

13 export gas containers

14 plant for the chemical absorption of CO ₂

15 compressor

16 aftercoolers

17 reduction shaft

18 lumps, pellets, sinter and additives

19 Reduction gas for reduction shaft 17

20 fifth control device (valve)

21 waste heat boiler

22 top gas from reduction shaft 17

23 cyclone for Topgas 22

24 Dust from cyclone 23 or hot gas filter 11

25 dust and fine ore from separator 59

26 wet scrubbers

27 excess gas

28 cooling gas

29 first injector

30 bag filter

31 first process gas line

32 second process gas line

33 second injection device

34 relaxation turbine 35 For raw material drying (coal, fine coal or

Ore drying) or to the power plant

36 bypass line

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 first control device

46 second control device (valve)

47 fine ore

48 melter gasifier

49 lumpy coal

50 coal in powder form

51 iron briquetting

52 conveyor system

53 designed as a fixed bed reactor storage container for

Preheating and reduction of iron oxides and / or iron briquettes

54 top or generator gas from melter gasifier 48

55 top gas from storage tank 53

56 fourth control device (valve)

57 third control device (valve)

58 hot metal and slag

59 separators for fine ore

60 wet scrubbers for excess gas 61

61 surplus gas

62 wet scrubber for cooling gas

63 gas compressor

64 CO _{2 released} gas (product gas) from absorber 17

65 cold iron briquettes

66 wet scrubber for top gas from storage tank 53

67 first temperature sensor

68 second temperature sensor 69 third temperature sensor

70 first line to the flare system 72

71 second line to the flare system 72

72 torch plant

73 pressure sensor

74 Bypass line for expansion turbine 34

75 export gas cooler

76 cold water

77 gas cooler for recirculation gas

78 cold water

79 recirculation gas

80 recirculation gas compressor

81 recirculation gas cooler 79 and 9, respectively

82 residual gas from Annex 14

83 combustion air for reducing gas furnace 6

84 residual gas line

Claims

claims

1. Method for controlling the temperature of process gases

(12) from pig iron production plants for use in an expansion turbine (34)

characterized in that the inlet temperature of

Process gas (12) when entering the

Relaxation turbine (34) is set so that it does not fall below a minimum inlet temperature at which in the expansion turbine condensation

occurs, and / or that the process gas (12) is cooled, so that the exiting the expansion turbine process gas when entering a low-pressure gas storage

(13) a maximum allowed for this

Inlet temperature by at least one of the following measures:

Heat recovery steam generator (21), which flows through the process gas (12) before entering the expansion turbine (34),

- Control of the process gas temperature by controlling the amount of process gas, which at the

Waste heat recovery plant, in particular the

Heat recovery steam generator (21), passed uncooled past (36), Admixing cooled, pressurized further process gas (27) to the process gas (12) in front of the expansion turbine (34),

Injecting (29, 33) water into the process gas (12),

- Adding cold residual gas (82) from a plant (14) for C02 ~ removal to the process gas (12) after the expansion turbine (34).

A method according to claim 1, characterized in that as the process gas (12) exhaust gas is used, which was previously removed from the plant for pig iron production and after the expansion turbine (34) is not returned to the plant for pig iron production.

A method according to claim 1 or 2, characterized

in that top gas (9) from a blast furnace, in particular from an oxygen blast furnace (1), is used as the process gas and optionally as further process gas.

A method according to claim 1 or 2, characterized

characterized in that exhaust gas (22, 27, 44) from a smelting reduction plant (17, 37-40, 48) is used as the process gas and optionally as further process gas. A method according to claim 4, characterized in that at least one of the following exhaust gases is used:

Exhaust gas (27) from a melter gasifier (48), Exhaust gas (44) from at least one reduction reactor (37-40),

- Exhaust (22) from at least one fixed bed reactor (17), in particular for preheating and / or reduction of

Iron oxides and / or iron briquettes.

6. The method according to any one of claims 1 to 5, characterized

characterized in that the inlet temperature of

Process gas (12) when entering the

Relaxation turbine (34) not below the minimum

Inlet temperature of about 145 ° C is located.

7. The method according to claim 6, characterized in that the inlet temperature of the process gas (12) at

Entering the expansion turbine (34) is set to a value in the range of 150-175 ° C.

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

characterized in that the process gas (12) before or after the expansion turbine (34) is cooled so far that the maximum inlet temperature in the

Low-pressure gas storage (13) of about 80 ° C not

is exceeded.

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

characterized in that at least a portion of the process gas (12) before the expansion turbine (34) is dedusted dry. Apparatus for carrying out the method according to one of claims 1 to 9, characterized in that the

Plant for the production of pig iron with at least one first process gas line (31) for the introduction of

Process gas (12) in an expansion turbine (34) is connected, and the expansion turbine (34) through a second process gas line (32) with a

Low-pressure gas storage (13) is connected to process gas, wherein additionally at least one of the following facilities is provided:

- A first control device (45) and one before the expansion turbine (34), in particular in the plant for pig iron production, arranged

Waste heat recovery system, in particular a

Heat recovery steam generator (21), the first

Control device (45) for the

Waste heat recovery system (21) for controlling the

Process gas temperature is used,

- A second control device (46) and a

Bypass line (36), the second

Control device (46) for controlling the amount of process gas, which is passed uncooled past the waste heat recovery system, in particular the waste heat steam generator system (21), by means of a bypass line (36), - A third control device (57), with which the amount of cooled, pressurized further

Process gas (27) from the plant for pig iron production, which is passed into the first process gas line (31) is controlled,

- A fourth control device (56), with which the amount of water, which by means of a

Injection device (33) in the first (31) or second process gas line (32) can be injected, is regulated,

- A fifth control device (20), with which the amount of cold residual gas from a system for CO ₂ removal by means of a residual gas line (84) in the second process gas line (32) to the process gas (12) is mixed, is regulated.

11. The device according to claim 10, characterized in that at least one line is provided, with which top gas (9) from a blast furnace, in particular from an oxygen blast furnace (1) with Topgasrückführung, in the first process gas line (31) can be passed.

12. The device according to claim 10, characterized in that at least one line is provided, with which exhaust gas (22, 27, 44) can be passed from a smelting reduction plant in the first process gas line (31). Apparatus according to claim 12, 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 (17), in particular for

Preheating and / or reduction of iron oxides and / or iron briquettes.

Device according to one of claims 10 to 13, characterized in that in front of the expansion turbine (34) is arranged a system (11, 23, 30) for dry dedusting of the process gas (12).