WO2013011089A1 - Method and device for the dust removal and cooling of converter gas - Google Patents

Abstract

The invention relates to a method for the dust removal and cooling of converter gas and to a device for carrying out the method. According to the method for the dust removal of converter gas, converter gas that accumulates during the production of steel is first subjected to an indirect cooling in a first cooling device, preferably while generating steam and/or hot water, and then to an additional cooling in a second cooling device (6). The dust is subsequently removed from the gas to a dust content of < 5 mg/Nm³ using filters in a dust removing device (8). The converter gas leaves the first cooling device in which the gas was subjected to an indirect cooling, preferably while generating steam and/or hot water, at a temperature of ≤ 1100°C, preferably ≤ 950°C, particularly preferably ≤ 750°C, and ≥ 350°C, preferably ≥ 400°C, particularly preferably ≥ 450°C, most particularly preferably ≥ 500°C. A dry or semi-dry cooling is carried out in the second cooling device (6), preferably to a temperature of ≤ 280°C, particularly preferably to a temperature of ≤ 250°C, most particularly preferably to a temperature of ≤ 200°C.

Description

 description

Name of the invention

Method and device for dedusting and cooling of

 converter gas

Field of engineering

The present application relates to a method for dedusting and cooling of converter gas and to an apparatus for carrying out the method.

State of the art

When raw iron is oxygenated, the accompanying elements of the pig iron are oxidized by the oxygen and separated from the iron. While the oxides of Si, Mn and P are removed from the steel bath in the form of slag, carbon escapes in gaseous form as carbon monoxide CO from the steel bath. The resulting from the fresh carbon monoxide fraction in the so-called converter gas, which escapes from the converter containing the steel bath, gives the converter gas a large amount of energy. By chemical conversion into carbon dioxide C0 ₂ , this energy content can be obtained later, for example by combustion of CO or by reduction of metal oxides by means of CO. For this it is known that

To collect and store converter gas. For this purpose, the converter gas is subjected to dedusting - for example, electrostatically - and cooling. Usually, the inlet temperature of the dedusted and after dedusting again cooled converter gas when entering a

Storage device 50-70 ° C. By cooling the converter gas can be stored in a given volume of a storage device, a larger amount of substance converter gas than in uncooled introduction of the

Converter gas into the storage device.

In today used as standard wet dedusting for the converter gas is the converter gas, which in cooling chimney indirectly to produce Steam or hot water was cooled to a temperature of about 900 ° C, subjected to a multi-stage wet dedusting for coarse and fine dust removal. The cooled and dedusted converter gas thus obtained is, if appropriate after further cooling in a gas cooler, often introduced into a gas storage device, with a dust content after the wet scrubber of usually 20-30 mg / Nm ^{3 being} realized. The water used in wet dedusting must also be subjected to an elaborate treatment. In addition, high operating costs, because water losses are compensated and incurred wastewater must be elaborately aftertreated. A further contribution to high operating costs is made by the high power requirement of the pump system necessary for the circulation of the water, the high proportion of energy for overcoming the pressure loss in the purification stage and the high space and investment requirements, which are necessary for the water supply and - aftertreatment

System parts results.

For today standard dry or

Quasitrockenentstaubungen the converter gas, which was cooled in the cooling chimney indirectly to produce steam or hot water to a temperature of about 900 ° C, the evaporation cooling to the

 Temperature reduction to about 300 - 200 ° C subjected to then in

Electrostatic precipitators to be dedusted. The resulting cooled and dedusted converter gas is often introduced into a gas storage device after further cooling in a gas cooler, usually a quench, with a dust content of usually 10 - 20 mg / Nm ^{3 is} realized after electrostatic precipitator. Even when using a gas cooler, especially one

Quench, a water treatment for accumulating wastewater must be provided.

Due to environmental requirements and technical requirements of plants in which the converter gas is used, the lowest possible dust content of the converter gas is sought.

Summary of the Invention Technical Problem

 It is the object of the present invention, a method and a

To provide apparatus by which the disadvantages of the prior art are reduced or avoided, and a dust content of the dedusted converter gas of <5 mg / Nm ^{3 is} achieved.

Technical solution

 This object is achieved by a method for dedusting and cooling converter gas,

wherein converter gas obtained in the steelmaking is first subjected to indirect cooling in a first cooling device by heat exchange between the converter gas and a liquid cooling medium, preferably under steam and / or hot water production,

then subjected to further cooling in a second cooling device, then dedusted in a dedusting device.

The inventive method is characterized in that

the converter gas leaves the first cooling device at which it has undergone indirect cooling by heat exchange between the converter gas and a liquid cooling medium, preferably under steam and / or hot water production, at a temperature

<1 is 100 ° C, preferably <950 ° C, more preferably <750 ° C, and which is> 350 ° C, preferably> 400 ° C, more preferably> 450 ° C, most preferably> 500 ° C, and that the first cooling device leaving converter gas is introduced into the second cooling device, and in the second Cooling device dry or quasi-dry cooling, preferably to a temperature <280 ° C, more preferably to a temperature <250 ° C, most preferably to a temperature <200 ° C takes place,

and dedusted in the Entstaubungsvornchtung by means of filters to a dust content of <5 mg / Nm ³ .

The converter gas accumulates when refining pig iron batches for steel production in a converter. The converter may be, for example, an AOD converter for producing stainless steel, or an LD converter for performing an LD method with inflation of oxygen, or a bottom-blowing converter, or a combined bottom and on-up converter.

AOD stands for Argon Oxygen Decarburization.

LD stands for the Linz-Donawitz process. The indirect cooling takes place with energy transfer from the converter gas to a liquid cooling medium in a first cooling device. The liquid cooling medium is preferably water. Preferably, the indirect cooling is carried out with the liquid cooling medium under steam or hot water production.

The first cooling device can be designed at least partly as a cooling chimney. The term "cooling chimney" is understood to mean a gas channel consisting of tube segments, on the inner surface of which a heat exchange takes place between the converter gas and a cooling medium guided in tubes. By extending a conventional cooling chimney, converter gas is more strongly cooled until it leaves the chimney using the heat of the converter gas.

 An increase in efficiency in cooling can also be achieved within the

Gas channels additional exchange surfaces, such as so-called

Bulkheads to be installed. Steam generation takes place by passing water under high pressure through the

Cooling medium - preferably water - leading tubes is pumped. In the removal of the heat energy of the converter gas steam is formed, which is collected in a steam drum and for further use in the

Metallurgical plant is available. Through the use of thermal

 Caching, it is subsequently possible, for example, to use the steam for continuous power generation. The purpose of steam generation is to use the energy available in the hot converter gas - which leaves the converter at temperatures of up to 2000 ° C - for other uses

recover. In addition to or instead of steam generation can be withdrawn in the first cooling device in another way energy by indirect cooling from the converter gas, for example by means of

Hot water production.

 Steam generation or hot water production makes economic sense only at a gas temperature of 350 ° C or higher, because at lower temperatures for the required heat transfer ever larger heat exchanger surfaces must be present, on the one hand in the purchase high costs and space problems with it, but also in operation Higher energy costs - such as higher pressure drop - have a negative economic impact.

 In principle, steam generation or hot water production could be carried out even at temperatures below 350 ° C, but such a process is not economically acceptable for the reasons mentioned above.

The energy transfer in the indirect cooling in the first cooling device can of course be carried out instead of water or steam with other media, such as molten salts or organic liquids. After the indirect cooling of the converter gas in the first cooling device, which preferably takes place with steam generation or hot water generation, to a temperature

<1 100 ° C, preferably <950 ° C, more preferably <750 ° C, and> 350 ° C, preferably> 400 ° C, more preferably> 450 ° C, most preferably> 500 ° C,

the converter gas is subjected to further cooling in a second cooling device, and then dedusted in a dedusting device by means of filtering to a dust content of <5 mg / Nm ³ .

In this case, the converter gas leaving the first cooling device is introduced into the second cooling device without coarse dedusting taking place between leaving the first cooling device and entering the second cooling device

Cooler.

According to the invention, dry or quasi-dry cooling takes place in the second cooling device. For the purposes of this application, dry cooling means cooling in which the moisture content of the converter gas to be dedusted is not increased by supplying moisture into the converter gas. This is the case for example with indirect cooling by means of a heat exchanger, for example gas-liquid with a cooling liquid or gas-gas with a cooling gas.

Under quasi-dry cooling is in the context of this application a

To understand dedusting, in which the moisture content of the dedusting converter gas is increased by supplying moisture into the converter gas, while little or no wastewater, which has come into direct contact with the cooled gas stream during cooling, is obtained. Low wastewater is to be understood as meaning that less than 20%, preferably less than 10%, more preferably less than 5%, of a quantity of water introduced for cooling into a flow of converter gas is produced as waste water. In such small amounts of wastewater wastewater treatment can be operated with little effort or to dispense with a wastewater treatment. The dry or quasi-dry cooling in the second cooling device is preferably carried out to a temperature <280 ° C, more preferably to a

Temperature <250 ° C, most preferably to a temperature <200 ° C. Using filters, dust is removed to a dust content of <5 mg / Nm ³ .

Filters that can dust off to a dust content of <5 mg / Nm ³ are, for example, fabric filters, ceramic filters or steel filters. Tissue filters are understood to mean filter systems which consist of a fabric material but can take on a wide variety of forms such as, for example, cartridges, tubes, bags, cassettes. Of course, a gas to be dedusted must have a temperature that is below the temperature at which the material of the fabric filters begins to thermally decompose. Tissue filters can, for example, commercially available filter materials with a

Resistant to permanent operating temperature of> 200 °, such as polyamide P84, meta aramid, glass fiber, PTFE, carbon fiber or equivalent. However, the upper limit of resistance for use of such materials is at peak temperatures of about 280 ° C. In order to enable safe use, therefore, in many filter materials, the temperature of the converter gas must not be more than 280 ° C, preferably <200 ° C. When the converter gas is the first cooling device in which it was subjected to indirect cooling, preferably under steam or hot water production, with a

Temperature <1 100 ° C, preferably <950 ° C, more preferably <750 ° C leaves, it is possible with reasonable economic effort to cool by means of subsequent dry or quasi-dry cooling the converter gas to temperatures at which a use of fabric filters, especially of Tissue filters made of filter materials in which for safe use, the temperature of the converter gas is not more than 280 ° C, preferably <200 ° C, for dedusting is possible.

If heat-resistant filters made of special materials such as ceramic or steel - called ceramic filters, steel filters - are used at higher temperatures> 280 ° C, the filter can fulfill its filter function even at temperatures of up to 500 ° C or above. Despite further cooling of the converter gas in the second cooling device, temperatures of up to> 500 ° C. can occur on the filters themselves, and thus possibly destroy the filter material to lead. This can happen, for example, when pyrophoric on the

Filter material deposited dust, such as metallic iron, reacts with oxygen in the exhaust gas and is oxidized. Such oxidation is highly exothermic and can lead to temperatures> 500 ° C. Oxygen in the exhaust gas may occur in periods of operation of a converter in which no refining is performed, for example during charging or tapping.

Overall, the inventive method in its embodiments over the prior art, for example, the advantages

- Improved utilization of the heat of the converter gas by indirect cooling of the converter gas in the first cooling device, preferably under steam or hot water production, to a temperature <750 ° C, caloric converter gas higher calorie due to lower humidity - avoiding wet gas cooling, a converter gas with up to 40% higher energy content can be obtained, as an index here is the lower heating value H _u quoted, which increases from about 4.5 MJ / kg at a wet gas cooling to 6.5 MJ / kg in the inventive method - dust content < 5 mg / Nm ³

 - No or extreme against wet gas cooling

 reduced water requirement.

Advantageous Effects of the Invention

 Optionally, after dedusting in the dedusting device in a third cooling device, depending on the required gas temperature, dry, quasi-dry or wet cooled. This is done, for example, when the converter gas is to be introduced into a gas storage device. In order to economically carry out a storage of the dedusted converter gas if necessary, the dedusted converter gas is then cooled in a third cooling device, preferably to a temperature <70 ° C.

Because the cooling is dry or quasi-dry according to the invention, processing of wastewater coming into direct contact with the converter gas to be cooled can also be completely avoided at this point or carried out with little effort. According to an advantageous embodiment of the invention, the dry cooling takes place in the second cooling device and / or the third cooling device by indirect heat exchange. In indirect heat exchange, a gaseous or liquid cooling medium is kept spatially separated from the converter gas. Mixing of the cooling medium with the converter gas therefore can not take place. Accordingly, the cooling medium is not contaminated by contact with converter gas and accordingly does not have to be laboriously cleaned or disposed of. The moisture of the converter gas is not increased as a result of supply of moisture by contact between the cooling medium and the converter gas.

According to a preferred embodiment of the invention, the indirect heat exchange takes place in the second cooling device and / or the third

Cooling device by indirect gas-gas heat exchange instead. For example, the converter gas can be cooled by means of gas-gas heat exchange when cooling gas, for example ambient air, is guided by means of blowers via converter gas-carrying lines. The lines carrying the converter gas are preferably designed in the region in which cooling air is passed over them so that they have the largest possible surface-to-volume ratio. In this way, it is possible to cool particularly efficiently. The material of the conduits is preferably a metallic material at least in the region in which cooling air is passed over it. Steel is particularly preferred, since steel is easy to process, cost-effective and sufficiently heat-conductive for the purpose. For example, the converter gas lines leading in the area in which converter gas is passed over it, designed as a plate-shaped hollow body, introduced into the converter gas and can be discharged from which converter gas.

 The lines leading the converter gas can be formed in the area in which converter gas is passed over them, as pipes in the

Converted gas introduced and from which converter gas can be discharged. The cooling by gas-gas heat exchange can also be done without a fan. In this case, ambient air cooled by the lines leading between the converter gas is cooled. In principle, it is also possible to use existing blowers depending on the measured temperature of the cooled dedusted converter gas and selected

Thresholds for the temperature of the cooled but not yet dedusted, or the cooled and dedusted converter gas on or off, so that cooling either through the dedusted converter gas lines leading blown cooling air, or cooling takes place through the leading between the converter gas lines existing ambient air.

According to another embodiment of the invention, the indirect finds

Heat exchange in the second cooling device and / or the third

Cooling device by gas-liquid heat exchange with closed

Cooling circuit instead. For example, a liquid cooling medium in

Pipes are guided in a closed circuit, and the converter gas flow around the pipes. The liquid cooling medium may be, for example, water, or ammonia, or a mixture of ammonia and water. A mixing of the liquid cooling medium with the converter gas can not take place. Accordingly, the liquid cooling medium is not contaminated by contact with converter gas and accordingly does not have to be laboriously cleaned or disposed of. A preparation of the liquid cooling medium, for example a

 Water treatment, is not necessary in accordance with such process management.

 In the closed cooling circuit also re-cooling of heated liquid cooling medium takes place.

According to a further embodiment of the invention, the indirect finds

Heat exchange in the second cooling device and / or the third

Cooling device by a combination of indirect gas-gas heat exchange and gas-liquid heat exchange instead, for example, first gas-gas heat exchange and then further cooling by gas-liquid heat exchange.

According to one embodiment of the invention, the quasi-dry cooling takes place in the second cooling device and / or the third cooling device by an evaporative cooling process. In this case, a liquid cooling medium, for example water, injected into the gas stream of the converter gas. The droplet diameter d90 - d90 indicates that 90% of the droplets have a droplet diameter corresponding to a following size specification - the dosed liquid cooling medium is d90 <1000 microns, preferably <300 microns. To produce such fine droplets, for example, 2-fluid nozzles are used, which are operated for example with nitrogen, or high-pressure nozzles, for example

Return nozzles used.

 Conventionally used gas scrubbers acting as gas scrubbers have a droplet spectrum in which the droplet diameter d90 is greater than 1000 microns and operate at high L / G of about 2-5. L / G stands for the ratio of liters of cooling medium to cubic meters of gas to be cooled. In such an operation, a proportion of the cooling medium is evaporated - it evaporates - while the majority does not evaporate, but only heated. Evaporation and evaporation in this context are different terms for the same process. Since not the heat of evaporation is used to cool the gas stream from converter gas when heated, for a given cooling, the addition of more cooling medium will be necessary than if the whole or the majority of the

Cooling medium is evaporated. Accordingly, the gas coolers conventionally used as gas scrubbers are large

Circulating water volumes required.

 In the method according to the invention is characterized in that the liquid

Cooling medium is introduced as a mist of fine droplets, which - resulting in cooling the converter gas - evaporation of the cooling medium compared to conventional wet-working, acting as gas scrubbers gas coolers easier. This makes it possible to achieve a given cooling without an enormous excess of water with L / G of 2-5, which is necessary in conventional processes, but with a L / G substantially less than 1, preferably less than 0.5, particularly preferably less than 0.1, for example Range 0.05, reach. Since in the process according to the invention the injected liquid cooling medium, water, virtually completely evaporates, according to the invention, no or no flow occurs even with an evaporative cooling process during the cooling of a gas stream little wastewater, which has come into direct contact with the cooled gas stream during cooling.

 Low wastewater is to be understood as meaning that less than 20%, preferably less than 10%, more preferably less than 5%, of a quantity of water introduced for cooling into a flow of converter gas is produced as waste water.

 In this context, the term wastewater is also liquid

Cooling medium to understand, which has come in the cooling with the cooled gas stream in direct contact, and therefore must be prepared.

Another object of the invention is an apparatus for performing a method according to the invention, with a first cooling device for the indirect cooling of converter gas by heat exchange between the converter gas and a liquid cooling medium, preferably with steam and / or hot water generation,

a second cooling device for cooling the converter gas leaving the first cooling device,

and a dedusting device for dedusting the second

Cooling device exiting converter gas,

characterized in that

the second cooling device is a cooling device for the dry or

is quasi-dry cooling,

and that the first cooling device opens into the second cooling device, and the dedusting device is equipped with filters.

The first cooling device opens into the second cooling device. This means that between the first cooling device and the second cooling device no further device for the treatment of the converter gas is present as

for example, a coarse dedusting device.

As a result, the converter gas leaving the first cooling device is introduced into the second cooling device without coarse dedusting taking place between leaving the first cooling device and entering the second cooling device

Cooler. The Entstaubungsvornchtung is preferably taking into account to ensure explosion-proof, explosion-proof and

explosion-proof measures, such as with

Pressure relief flaps, executed.

The first cooling device for indirect cooling of converter gas is preferably a cooling device for indirect cooling of converter gas

Steam generation, or a cooling device for indirect cooling of

Converter gas with hot water production, or a cooling device for the indirect cooling of converter gas under steam and hot water production, or a cooling device for the indirect cooling of converter gas under steam or hot water production.

According to one embodiment, the device comprises filters which are designed as fabric filters.

 It is preferred that the material of the fabric filter is a material from the group

 - polyamide P84,

 - Meta Aramid,

- Glass fiber,

 PTFE,

 - Carbon fiber

 - metal mesh

includes.

The material of the fabric filter can also consist of a material from this group.

According to another embodiment, the filters comprise ceramic filters and / or metal filters. The filters may also be ceramic filters and / or metal filters.

In one embodiment, the device also includes a third one

Cooling device for cooling the converter gas exiting the dedusting device, wherein the third cooling device comprises a cooling device for dry, quasi-dry or wet cooling. According to one embodiment of the device according to the invention, in the second cooling device and / or the third cooling device, the cooling device for dry cooling comprises a device for indirect heat exchange. The cooling device for dry cooling may also be a device for indirect heat exchange.

According to one embodiment of the device according to the invention, the device for indirect heat exchange comprises a device for carrying out an indirect gas-gas heat exchange. The device for indirect

Heat exchange may also be an apparatus for conducting an indirect gas-gas heat exchange.

According to one embodiment of the device according to the invention, the device for indirect heat exchange comprises a device for carrying out an indirect gas-liquid heat exchange with a closed cooling circuit. In the closed cooling circuit also re-cooling of heated liquid cooling medium takes place.

 The indirect heat exchange device may also be a device for carrying out a closed-loop indirect gas-liquid heat exchange.

According to one embodiment of the device according to the invention, the device for indirect heat exchange comprises a device for carrying out an indirect gas-liquid heat exchange with closed cooling circuit and a device for carrying out an indirect gas-gas heat exchange.

According to one embodiment of the device according to the invention, in the second cooling device and / or the third cooling device, the cooling device for quasi-dry cooling is a device for carrying out a

Evaporative cooling process. According to one embodiment of the device according to the invention, nozzles for injecting a liquid cooling medium with droplet diameter d90 of the injected liquid cooling medium d90 <1000 micrometer are present in the apparatus for carrying out an evaporative cooling process.

Description of embodiments

The invention will be explained with reference to exemplary schematic figures of embodiments.

Figure 1 shows schematically the treatment according to the invention of

Converter gas.

In FIG. 1, converter gas 1, represented by corrugated arrows, rises from a converter into a suction hood 2. Through the suction hood is the

 Converter gas in the cooling chimney, which is a first cooling device for indirect cooling, in the case shown under steam generation, passed. The cooling chimney comprises the chimney parts 3a and 3b. Via pipes 4, steam, which is produced by heat exchange between the converter gas and the cooling medium, which is guided in the cooling chimney (not shown), is fed to a steam drum 5.

In the cooling chimney, a first cooling step for the converter gas takes place by means of indirect cooling by water / steam. At the end of the cooling chimney part 3a, the converter gas has a temperature of about 900 ° C and is further cooled in the chimney part 3b to a temperature of about 400 ° C.

After the converter gas exits the first cooling device, it enters a second cooling device 6; this will be the first cooling device

leaving converter gas introduced into the second cooling device. The first cooling device opens into the second cooling device. This means that between the first cooling device and the second cooling device no further device for the treatment of the converter gas is present as

for example, a coarse dedusting device. This is a cooling device for dry cooling, in the example shown by indirect gas-gas heat exchange. The cooling takes place in that the converter gas is passed through plate-shaped or tubular hollow body, via which 7 cooling air is blown by fans. In the second

Cooling device is cooled to <200 ° C.

The converter gas emerging from the second cooling device 6 is then passed into a dedusting device 8, in which it is dedusted by means of fabric filters 9 to a dust content of <5 mg / Nm ³ .

Subsequently, the cooled and dedusted converter gas from the

Dedusting device discharged. About a switching station 10, the cooled and dedusted converter gas can be passed to a flare chimney 1 1, where it is burned. It may alternatively be directed to a gas storage device 12.

 For example, the converter gas is then led to the flare chimney 1 1, if its CO concentration is below a threshold necessary for an economically useful further use. This may be the case during periods such as bubble start or end of bubble, or tapping periods at converter 1. When the CO concentration increases above the

Threshold, the converter gas is supplied by switching the switching station 10 of the gas storage device 12.

In the flow direction of the converter gas in front of the gas storage device 12, the cooled and dedusted converter gas is subjected to dry cooling in a third cooling device 13. This is a cooling device for dry cooling, in the example shown by indirect gas-gas heat exchange. The cooling takes place - as in the second cooling device 6 - characterized in that the converter gas is passed through plate-shaped hollow body through which blowers 14 cooling air is blown. LIST OF REFERENCE NUMBERS

1 converter

 2 exhaust hood

 3a, 3b Cooling chimney parts

 4 pipeline

 5 steam drum

 6 second cooling device

7 blowers

 8 dedusting device

9 fabric filters

 10 switching station

 1 1 torch fireplace

 12 gas storage device

13 Third cooling device

14 blowers

Claims

claims 1. Method for dedusting and cooling converter gas, wherein converter gas obtained in the steelmaking is first subjected to indirect cooling in a first cooling device by heat exchange between the converter gas and a liquid cooling medium, preferably under steam and / or hot water production, then subjected to further cooling in a second cooling device, then dedusted in a dedusting device, characterized in that the converter gas leaves the first cooling device at which it has undergone indirect cooling by heat exchange between the converter gas and a liquid cooling medium, preferably under steam and / or hot water production, at a temperature <1 is 100 ° C, preferably <950 ° C, more preferably <750 ° C, and> 350 ° C, preferably> 400 ° C, more preferably> 450 ° C, most preferably> 500 ° C, and that the first cooling device leaving converter gas is introduced into the second cooling device, and in the second cooling device dry or quasi-dry cooling, preferably to a temperature <280 ° C, more preferably to a temperature <250 ° C, most preferably to a temperature <200 ° C, and dedusted in the dedusting device by means of filtering to a dust content of <5 mg / Nm ³ . 2. The method according to claim 1, characterized in that after dedusting in the dedusting the converter gas in a third cooling device is dry, quasi-dry or wet cooled. 3. The method according to claim 1 or 2, characterized in that the dry cooling in the second cooling device and / or the third Cooling device takes place by indirect heat exchange. 4. The method according to claim 3, characterized in that the indirect heat exchange takes place by indirect gas-gas heat exchange. 5. The method according to claim 3, characterized in that the indirect heat exchange by gas-liquid heat exchange with closed Cooling circuit takes place. 6. The method according to claim 3, characterized in that the indirect heat exchange takes place by a combination of indirect gas-gas heat exchange and gas-liquid heat exchange. 7. The method according to claim 1 or 2, characterized in that the quasi-dry cooling takes place in the second cooling device and / or the third cooling device by an evaporative cooling process. 8. Apparatus for carrying out a method according to one of claims 1 to 7, with a first cooling device for the indirect cooling of converter gas by heat exchange between the converter gas and a liquid cooling medium, preferably with steam and / or hot water generation, a second cooling device for cooling the converter gas leaving the first cooling device, and a dedusting device for dedusting the second Cooling device exiting converter gas, characterized in that the second cooling device is a cooling device for the dry or is quasi-dry cooling, and that the first cooling device opens into the second cooling device, and the dedusting device is equipped with filters. 9. Apparatus according to claim 8, characterized in that the filters comprise fabric filters. 10. The device according to claim 9, characterized in that the material of the fabric filter is a material from the group  - polyamide P84,  - Meta Aramid,  - Glass fiber,  PTFE, - Carbon fiber  - metal mesh includes. 1 1. A device according to claim 8, characterized in that the filters comprise ceramic filter or metal filter. 12. Device according to one of claims 8 to 1 1, characterized in that it also has a third cooling device for cooling of the Dust removal device exiting converter gas, wherein the third cooling device comprises a cooling device for dry, quasi-dry or wet cooling. 13. Device according to one of claims 8 to 12, characterized in that in the second cooling device and / or the third cooling device, the cooling device for dry cooling, a device for indirect Heat exchange is. 14. The apparatus according to claim 13, characterized in that the Indirect heat exchange device comprising an apparatus for performing an indirect gas-gas heat exchange. 15. The apparatus according to claim 13, characterized in that the Device for indirect heat exchange device a device for carrying out an indirect gas-liquid heat exchange with closed cooling circuit. 16. Device according to one of claims 8 to 12, characterized in that in the second cooling device and / or the third cooling device, the cooling device for quasi-dry cooling comprises a device for carrying out an evaporative cooling process.