Rotary Gas Gas Heaters for applications on coke plants
Design and supply of high performance rotary Gas Gas Heaters for operation on coke plant, coal charging gas DeSOx application.
Cangzhou Zhongtie steel plant is a large-scale comprehensive iron & steel enterprise integrating coking, iron-making and steelrolling. The GGH application was within the coke production.
Challenge
Coking is a process in which coal is heated to above 1000°C in the absence of air to produce coke, an essential ingredient for smelting iron in a blast furnace. So far, there is no alternative to coke in large-scale steelmaking and the challenge was to remove the sulphurous emissions within the flue gas from slot type coke oven batteries. The coking process has inherent emissions, the only solution is to the remove the resulting emissions before they are released into the atmosphere.
This was a novel application for a rotary Gas Gas Heater (GGH). The unusual part of this process was the intermittent release of flue gas for only 3 minutes in every 10 as shown in the Process Flow Diagram below. This is a result of each individual slot oven having the coke, which it has produced, being pushed out from the side door and then being re-charged with coal from the top.
The flue gases are drawn out under suction to avoid direct emissions whilst charging and are then treated in a dry Flue Gas Desulphurisation (FGD) with sodium bicarbonate, (NaHCO3) to remove SOx before going to the chimney. Similarly to sinter plant NOx reduction systems, the GGH is used to minimise the required gas burn heat input in the DeSOx process.