Study On The Briquetting Of Pulverized Coal And Calcium Oxide And Pyrolysis Characteristics Of The Briquettes

In coal based calcium carbide producing process,coal is taken as a carbonaceous material,molding with calcium oxide calcium to get coal-CaO balls?CBs?,conducting the pyrolysis process to get carbonized compacted coal-CaO balls?CCBs?and producing calcium carbide in the calcium carbide furnace.In this paper,the effects of molding and pyrolysis conditions on the properties of CBs and CCBs were studied.The effects of adding a large amount of calcium oxide under the molding condition on three-phase products were investigated.The pyrolysis behaviors of the CBs component in the pyrolysis process were also studied.To explore the process of molding,the effects of particle size,binder amount,forming pressure,amount of additive and preheating temperature on the properties of compacted coal-CaO balls were investigated by using presses.The results showed that under the existing conditions of the experiment,the optimum condition to prepare compacted coal-CaO balls?CBs?is using the coal less than 0.05 mm,adding 24% binder,coal: CaO = 1: 1,coal tar pitch: additive A = 10: 1,heating to 160? and forming pressure 65 kN.To explore the process of pyrolysis,the effects of particle size,binder addition,molding pressure,pyrolysis temperature,constant temperature and heating rate on the pyrolysis characteristics and the mechanical strength of carbonized compacted coal-CaO balls were investigated by using fixed bed pyrolysis device.The results showed that under the existing conditions of the experiment,the optimum condition to prepare CCBs is using the coal less than 0.05 mm,adding 26% binder,coal: CaO = 1: 1,coal tar pitch: additive A = 10: 1,heating to 160?,forming pressure 70 kN,pyrolysis temperature 700?,heating rate 5?/min,holding 30 min and 120mL/min of gas carrier.The weight loss behavior of the binder during the pyrolysis process and the composition of the tar product of each component were investigated by using the thermogravimetric analysis and simulated distillation.Residue of the binder in CCBs accounted for 11.44% to 13.09% of the mass of CCBs.The effects of adding a large amount of calcium oxide under the molding condition on three-phase products were investigated by heating CBs and coal briquettes under different temperature and using industrial analysis,elemental analysis,pickling and alkaline cleaning,chromatographic column,GC-MS and GC.Compared to coal briquettes,the solid phase product of CBs has high volatile,low carbon content.And adding a large amount of calcium oxide has sulphur capture effect.Compared to coal briquettes,the liquid phase pyrolysis product of CBs has lower phenols and naphthols significantly,lower quinoline and pyridine significantly,higher olefins,higher naphthenes and naphthalene,lower PAHs and ethers.So that the weight component decreases,the content of light components increases,and the addition of large amount of calcium oxide under the molding conditions could improve the quality of coal tar.Compared to coal briquettes,H2 S was not measured in the gas phase pyrolysis product of CBs,and the yield of H2,CH4,CO increased,while the yield of CO₂ was significantly decreased.