Design And Evaluation On Dust Removal Process Of Coal Plasma-pyrolysis Gases For Producing Acetylene And The Development Of Absorbents

In the process of coal plasma-pyrolysis for acetylene producing,dust removal process between the quench unit and the gas separation unit was essential to purify the particulate matt(below 1 mg/Nm3)as well as the coal tar in pyrolysis gases to meet the requirement for the following gas separation process.However,single dust removal device/process is not sufficient to achieve this requirement,since the pyrolysis products which contain a large number of water vapor,coal tar,dust and other substances are complex mixtures with flammable and explosive properties.It is highly urgent to design an efficient,economical and stable dust removal combined process which is suitable for the properties of the dust in pyrolysis gases.From literatures,a wet dust removal process consisting of a cyclone,a jet bubbling tower with a wet electrostatic precipitator,and a dry dust removal process including a cyclone,a ceramic candle filter with a high temperature pulse-jet baghouse were proposed in this paper.The key parameters of the equipment as well as the safety and economy of this process mentioned above were calculated and evaluated.The results indicated that dry process was more economical whose annual operating cost was 47.0%of the wet process,while the wet process was safer and more reliable.Furthermore,a preliminarily screening study of an absorption solution of the wet dust removal process was performed to improve the coal tar removal efficiency and to prevent the absorption loss of acetylene.The simulated coal tar used herein which consist of liquid paraffin or isobutyl benzene.The influences of the types of emulsifier and defoaming agent,addition amount and hydrophilic lipophilic balance(HLB)of emulsifier on the acetylene absorption and simulated coal tar dissolution were studied.The results showed that:(1)The absorption solution with 1.0 wt.%mixtures of tween 60+span 80(HLB=8.6)was of best performance for liquid paraffin-water system.(2)The absorption solution with 0.5 wt.%mixtures of tween 20+span 80(HLB=8.6)addition was the optimal one for isobutyl benzene-water system.On this basis,well defoaming effect could be obtained by adding 1.0 wt.%simethicone(viscosity 500±30 mPa·S)in the above absorption solution,showing little effects on acetylene absorption.