Experimental Study On Preparation Of Powder Activated Coke And By-product Pyrolysis Gas By Rapid Pyrolysis Of Pulverized Coal

The air pollution dominated by soot has been a major problem in China,and the situation of SO₂ emission reduction is very severe.At the same time,China is also a large importer of sulphur resources with poor sulfur resources.Under this background,the dry-process flue gas desulfurization technology with activated coke which can realize sulfur resources recovery was gradually got attention.But the production cost of traditional granular activated coke is very high,which prevent it from large-scale popularization and application.To overcome the high cost of traditional granular activated coke preparation,our team have proposed and developed one-step process for preparation of amorphous powder activated coke by rapid pyrolysis of pulverized coal and made a systematic study which have confirmed the feasibility of the technique.However,the previous research work of our team were mainly focused on the solid products of powder activated coke preparation process,and there was still a lack of research on the gas products of this preparation process—the pyrolysis gas of coke preparation.Besides,there was great difference between the experimental conditions of powder activated coke preparation and actual application.Therefore,it is necessary to do further study on the effects of preparation parameters on the pore structure characteristics of activated coke and the pyrolysis gas of coke preparation.In view of the drawbacks of previous research work,in this paper,the experimental system for the preparation of powder activated coke was improved firstly,which ensured that the pyrolysis gas of coke preparation could be analyzed and tested while the powder activated coke was prepared Then,based on this experimental system with adding East Mongolia lignite as raw materials for coke preparation,we have redesigned the experimental conditions which are more suitable for practical application.The effects of the preparation temperature,excess oxygen coefficient and reaction atmosphere on the pore structure characteristics of activated coke and pyrolysis gas of coke preparation were investigated.The study on pore structure characteristics of activated coke showed that the preparation temperature could promote the formation and development of pore structure especially micropore structure of activated coke,but the pore structure of activated coke would be destroyed when the temperature was too high.The increase of excess oxygen coefficient could greatly improve the burn-off of activated coke,resulting in severe damage of the pore structure of activated coke due to excessive ablation.The change of the concentration of oxygen,carbon dioxide and water vapor in the reaction atmosphere could affect the pore structure of activated coke,especially,the effect of oxygen concentration was the most obvious,besides,the presence of carbon dioxide could inhibit the formation of mesopore and macropore structure to some extent,and the increase of water vapor concentration could promote the development of more micropore into mesoporous structure.The study on pyrolysis gas of coke preparation showed that the increase of preparation temperature could promote the incomplete combustion reaction of C and O₂ at the same time increasing the release rate of the volatile matter of the raw coal particles,besides,as a result,the yield of CO was greatly improved;The increase of excess oxygen coefficient would make the complete combustion reaction of C and O₂ to CO₂ gradually occupy the major portion,leading to the sharp decrease of CO and H₂.The change of the concentration of oxygen,carbon dioxide and water vapor in the reaction atmosphere have variety effects on pyrolysis gas of coke preparation,and when the oxygen concentration was 6%,the yield of CO and H₂ reach to the peak.While the increase of CO₂ concentration could improve the yield of CO,but have no effect on the yield of H₂.Besides,the increase of water vapor concentration was beneficial to the formation of H₂ and CO₂,as a result,it would consume more CO.Finally,according to the research findings of the mechanism experiment,within the range of experimental conditions in this thesis,the optimum conditions of activated coke preparation were as follows:the preparation temperature was 950 ℃,the excess oxygen coefficient was 0.3,the oxygen concentration was 6%,the carbon（?）design principle was put forward,then a 1MW pilot scale test system of powder activated coke preparation was designed and built.The test was carried out and the result showed that the pore structure characteristics,SO₂ adsorption capacity of activated coke prepared by the pilot test and pyrolysis gas composition were similar to the principle test,which verified the design principle and method of rapid preparation of powder activated coke by pulverized coal...