Tovshchik Natalia

Faculty of ecology and chemical technology

Department of ore-thermal processes and low-waste technologies

Speciality "Ecology and Environmental protection"

Development of technology for dry cleaning blast furnace gas

Scientific adviser: Vladimir Kochura 

Contents

Blast furnace production has a great influence on environmental contamination as by pig-iron production a considerable quantity of gas emissions and a waste is formed. Blast furnace gas has special value, considering it is expedient and its further use therefore there is an improvement of ecological conditions at the enterprises is actual. But that the further use of blast furnace gas possible began necessary for separating from it throat a dust which also has high raw value and it can be used in production.

Presently the problem of pollution of atmosphere, in particular emissions from metallurgical units is sharp. Operating schemes of clearing of blast furnace gas reduce in the wet way efficiency of use of domain gas as secondary power resources, also because of saturation blast furnace gas by water steams its warmth of combustion decreases, and physical heat is completely lost with water steam. Problematic use recovery turbine (RT) because of presence of water steam also is. Thus, transfer of blast furnaces from wet gas purification on dry is actual.

On the basis of the analysis and the executed review of researches on the given theme at the various enterprises the technology of clearing of blast furnace gas is developed in the dry way, and also recommendations about use of blast furnace gas as secondary power resources are developed.

Improvement of ecological conditions at the metallurgical enterprises, decrease in the expense of water in blast furnace shop, economy of power resources as a result of use of blast furnace gas as fuel.

Working out of technology of clearing of blast furnace gas by dry way for the purpose of improvement of ecological conditions at the metallurgical enterprises, decrease in the expense of water in blast furnace shop, economy of power resources, increases in degree of use of secondary power and material resources of blast furnace production.

To clearing of blast furnace gas at blast furnace metal works apply the multistage combined schemes.

Depending on presence or absence RT, at blast furnace factories two schemes of clearing of blast furnace gas usually apply:
1) a blast furnace – a dry deduster – injector a hollow scrubber – a pipe of Venturi – spray catcher – throttle group – spray catcher – pure gas to the consumer;
2) a blast furnace – a dry deduster – injector a hollow scrubber – a pipe of Venturi – spray catcher – the wet electrofilter – pure gas on electric power reception in RT. Open Company NPP "Dneproenergostal" innovation now is the system of dry clearing of blast furnace gas with application hose the filter with pulse regeneration which is used for clearing of a dust of the blast furnace gas allocated in the course of work of blast furnaces of the metallurgical enterprises, by means of a method of a dry filtration through filtering elements [1].

In the world use various schemes of clearing of blast furnace gas. So, for example, to the USA, the system of clearing of blast furnace gas usually includes a cyclone, a scrubber and wet electrofilters or a two-level scrubber [3,4].

In the world a number of devices of dry clearing of blast furnace gas is developed: the lamellar electrofilter and threw the fabric the filter. The first installation of dry clearing of blast furnace gas is constructed in Finland, it is equipped by firm Lurgi electrofilter, experience of Japan here was made use.

At Japanese factory Chiba of the company of Kawasaki Steel is successfully maintained system of dry clearing of blast furnace gas with use hose the filter [3].

Gas purification of dry type it is intended for preliminary rough clearing of blast furnace gas of a dust. A number of foreign firms (Bishoff, P.Vjurt, Lurgi, etc.) apply two dedusters - radial and tangential.

At some enterprises of Japan (Nippon Kokap K. K Fuкuуама ВF № 2, 5, Ogishima-BF №2) and China (Shougang соrроrаtion, ВF №2) after dedusters is applied by dry electrofilters or fabric filters to increase of overall performance RT. They settle down in parallel installations of gas purification of wet type which remain in operation at smaller loadings [5].

Clearing of blast furnace gas by dry way

The most effective way of catching finely divided a dust from departing gases and aspiration emissions of various technological processes and units is the filtration. During realization of this process gases pass through filtering material in which quality the fabric with various characteristics is used.

In the given work replacement of operating wet schemes of clearing of blast furnace gas on dry which has been developed on the basis of foreign experience at Open Society  "Zaporizhstal" enterprise is offered [2].

The similar scheme which is used on one of Japanese factories, is resulted in drawing 7.1.

1 – a blast furnace; 2 – a deduster; 3 – throttle group; 4 – shut-off valves; 5 – hose the filter;6 – RT; 7 – a pressure regulator.

Drawing 7.1 – Technological scheme dedusting shaft top gases a dry method with the help hose the filter [2]

In the integrated kind the fabric filter represents the metal case in which the filtering elements consisting of fabric sleeves, dressed on metal wire skeletons take place. For regeneration of filtering elements the pulse purge by the compressed air through high-speed blowing-off valves is used.

Efficiency dedusting gases in the filter depends on dispersion of particles of a dust, characteristics of a filtering cloth, a way and a mode of regeneration, size specific gas and dust loading, hydraulic resistance of the device.

Filters are equipped by highly effective and reliable system of regeneration by the compressed air with application of high-speed blowing-off valves. Installation work is completely automated [2].

The first results of work of gas purifications have confirmed high economic and ecological efficiency of use of a dry way of clearing blast furnace gas. Dry clearing will allow:
- to get stable and effective work RT for electric power development because concentration of a dust in blast furnace gas decreases to 2-3 mg/m³ that increases service life hot-blast stove, and also raises productivity RT on 30% and stability of shovels RT –  till 1 year;
- to increase use SMR in connection with a formation exception scoria;
- to exclude from manufacture use of water for wet gas purifications in this connection volumes of building of some objects of a water management of a blast furnace are excluded or reduced: scoria pumping over station of gas purification, sediment bowls and flocculation agent scoria, pump station of swapping of a pulp, circulating pump station of a turnaround cycle of gas purification, etc.;
- to raise temperature of heating of blast furnace blasting and to use physical warmly blast furnace gas because the temperature of gas after dry clearing makes 100-120ºС that on 50-70ºС above, than at use of wet gas purification; humidity of gas decreases on 50-60 g/m³ that the increase in caloric content of blast furnace gas at 50-60 kcal /m³ is in aggregate equivalent;
- to improve ecological conditions at factory in connection with better clearings of gas of a dust and elimination slag economy.

At a writing of the given abstract master work isn't finished yet.

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