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Contenuto archiviato il 2022-12-27

PNEUMATIC INTRODUCTION OF COKE BREEZE CHARGE INTO CUPOLA FURNACE

Obiettivo

To verify on an industrial scale the technical and economic validity of introducing coke scraps of differing granulometry into the comburant air zone of continuously operating hot blast cupolas, thereby utilizing a product (coke breeze) of high heat and energy content which would be otherwise degraded as a difficult to use, low cost by-product. Scraps recovery of +- 1,400 T/y. will yield a net saving of +- Lit. 170 million. Payback is estimated at 2.2 years.
The project began in December 1982 and work was halted in April 1985. The melting system is considered the heart of the foundry. It supplies liquid metal for the casting line in quality and quantity required. For this reason it has to be technically reliable and economically profitable. Problems arose with the demonstration plant, particularly with clogging and erosion of piping, inconsistency of the coke breeze dose, maintenance difficulties and the gravity feed: consequently the contractor decided it was prudent to abandon the project. It did however yield the following results:
- the efficiency of the coke breeze, blown-in from the tuyeres exceeded 90%;
- pressure inside the cupola is not influenced by the blowing-in of the coke breeze;
- for the introduction of the coke breeze up to +- 500 kg/h, the melting area inside the cupola does not change place;
- working of the cupola does not undergo variations, in fact there appears to be a tendency to work without oxidation (insufficient data makes it impossible to be more exact on this point);
-coke analysis is prefectly controlled;
- maximum allowable humidity in the coke, for the plant to be able to work well, must not exceed 1.5%.
The plant was installed at the Teksid factory and has an annual capacity of 130,000 T of mechanical castings in grey and modular iron, melted in the cupola.
The thermal efficiency of hot blast cupola furnaces depends on a charge of best quality coke. The gauged size of the coke is essential for the regular working of the cupola: this is achieved by sieving of the coke prior to introduction to the cupola.
The demonstrative plant had the function of substituting +- 4% of the coke (90-140 mm) with recovered coke breeze unusable in the cupola owing to its size (+- 8 mm). Coke breeze is collected directly under the coke vibrating screen, then transplanted pneumatically into the silos. From these it is gravity fed into a pneumatic system which meters correct dosage prior to injection, (by coaxially placed nozzles) to the tuyeres, into the coke bed area of the cupola. The solid charge takes more than 60 min. to reach the melting area, becoming iron in the composition required. It is necessary, if the injection system for the coke breeze is used, not to charge the corresponding amount of coke in the charge slip. (In fact the coke charge would have to be increased and take at least 1 hour to reach the melting area).

Argomento(i)

Invito a presentare proposte

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Meccanismo di finanziamento

DEM - Demonstration contracts

Coordinatore

TEKSID SPA ASTEK
Contributo UE
Nessun dato
Indirizzo
DIV. FONDERIE GHISA VIA G. AGNELLI 60
10022 CARMAGNOLA
Italia

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Costo totale
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