Gas-fired coke-cupola

The principle of the coke-gas cupola is to replace part of the coke with gas. There are two techniques for burning natural gas in the cupola using air-gas burners, located above the tuyeres using oxygas burners, located in the tuyeres. 

At present, the coke/air-gas cupola furnace finds limited implementation in Europe. This may be attributed to the difficulty in controlling the process and the increased complication of the furnace shell. 

The effect and use of the oxygas burner depends on the cupola concerned. In cold blast cupola furnaces, the technique is used to ensure easy restarts or to reduce the proportion of coke. In hot blast operation, the technique is used to increase the furnace capacity without modifying the melting bed. The replacement of part of the coke with CH4 results in a reduction in flue-gas voliune. This is used as a means of increasing the furnace capacity, without over-saturating the installed flue-gas cleaning system. 

The technique results in an increase in the carbon content of the melt and allows an increase in the amount of steel in the charge. The process provides a means of injecting FeSi, which is less expensive in powder form than as ore. These properties result in a beneficial economic effect. 

The replacement of part of the coke with CH4 results in a reduction in the flue-gas volume. In addition, the flue-gas is made more combustible due to the higher CO and H2 contents. If post combustion is present, the resulting flue-gases will show lower levels of organic compounds and CO. 

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