Calculation On Coke-oven Gas Consumption Of Direct Reduction Shaft Furnace

For direct reduction process with coke oven gas in shaft furnace,the consumption of coke oven gas need to be considered necessraly,which should include shaft belt,heating furnace,furnace cooling zone etc.CH₄ and C₂H₆ could react with O₂?similar to Midrex process?or H₂O?similar to HYL process?to split among coke oven gas.The paper calculted the conditions about the craking reaction of CH₄ and C₂H₆ reacted with O₂ and H₂O separately.The consumption of coke oven gas is mainy determined by chemical equilibrium and heat balance of the whole process,which include two parts,namely the amount of the reducing agent and consumption of heat source.The conclusions are as folowed:Craking reaction of CH₄ and C₂H₆ reacted with O₂:?1?.The amount of furnace gas consumption is determined by chemical and thermal balance.After being calculated,gas consumption of heat source were dominating compared with reduction agent.Thus thermal balance determined total amount of furnace gas.Besides reduction agent,there are two ways of heat adding in the craking reaction process of CH₄ and C₂H₆ reacted with O₂:a)directly adding gas amount as heat source;b)first the craking exothermic reaction of CH₄ and C₂H₆ transferred from heating furnace to shaft furnace?ZR?,then adding coal gas amount as heat source.?2?.Under ideal conditions?metallization rate being 100%?,"reducing agent+ZR+adding coal gas" method was adopted.If generating temperature of iron is 900?,2.58kg iron can be produced by 100 mol coke oven gas,namely,iron can be produced 278000 t/years by ovens with annual output of 600000 tons of coke oven gas.Under temperature of 845 ?,2.63kg iron can be produced by 100 mol coke oven gas,namely,iron produced 284000t/year,whch is the highest iron production by this method.?3?.Under actual conditions?metallization rate being10O%?,"reducing agent+ZR+adding coal gas" method could produce 2.43kg DRI with 100 mol coke oven gas,when iron generating temperature being 900?,namely iron can be produced 262000 t/years by ovens with annual output of 600000 tons of coke oven gas.?4?.When metallic iron formation temperature being 800?9500C in shaft furnace,heat income are 2 times higher than heat consumption in heating furnace.Then top gas after being purified can be used partly to heate new coke oven gas,others for other purposes.CH₄ and C₂H₆ could execute in the heating furnace on the one hand,on the other hand craking exothermic reaction happened in the shaft furnace with ZR?Zero Reformation?,providing heat for furnace improving DRI output of unit coke oven gas.?5?.The output of the shaft furnace cooling with gas can continue to use after water,so as long as the actual guarantee the usage can be enough,don't need to consume.When cooled exhaust gas temperature below 200?,can obviously improve the exhaust temperature to reduce the consumption of unit metal iron cooling capacity.When cooled exhaust gas temperature higher than 200?,improve the exhaust temperature to reduce the unit metal iron cooling consumed volume smaller.Therefore,controlled cooling exhaust temperature of 200? is the reasonable operating parameters.As shown in table 3.6,a)under ideal conditions,if of metallic iron cooling from 900? to 100?,150 ?,150?,cooled exhaust gas temperature is 200 ?,respectively to coke oven gas is 2093 m3/tFe,1995 m3/tFe,1893 m3/tFe,or per unit volume of the coke oven gas cooling capacity of 0.478 kg-Fe/m3 and 0.501 kg-Fe/m3.