Studies On Preparation And Properties Of Sulfur Retention Binder And Achnatherum Splendens Composited Briquette

Clean coal technology is the main measure to clean utilization of coal,which can significantly reduce the pollution caused by coal and increase the utilization efficiency of coal.Briquette technology which has the advantage of extensive applicability and convenient production is an efficient way of utilization of pulverized coal.The briquette binder is the core of briquette technology that decide the quality and function of briquette.The sulfur dioxide pollutant derived from coal combustion can be reduced significantly when adding sulfur retention agent into briquette binder.Therefore,researching the briquette binder which has the function of sulfur retention will be the key technology in the study of clean briquette.In this thesis,choosing five different kinds of raw coal acted as research objects,sulfur retention agent was prepared by controlling the different variables on the basis of that Sodium humic acid,limestone and slaked lime act as briquette binder and coal gangue,sodium chloride,sodium carbonate and ferrous chloride act as additives.The effects of sulfur retention agent on the parameters such as cold compressive strength,calorific value,volatile matter and ash content of briquette were studied,and the combustion efficiency and sulfur retention rate of the briquette were also evaluated.In addition,using clay and sodium humic acid as briquette binder and Achnatherum splendens as biomass additive,the performance of Achnatherum splendens briquette was evaluated on the basis of the coal with low sulfur content act as raw coal.The main contents are summarized as follows:1.Selecting Semi-coal powder with high content of fixed carbon as raw coal,sodium humic acid as organic binder,limestone and slaked lime as inorganic binders and sulfur retention agents,high-efficiency briquette binder was exploited.Studies showed that the amount of limestone and slaked lime of the raw coal are of 4.0% and 1.7%,respectively,the strength of briquette attained optimal state that about 280 N.However,the calorific value of briquette is reduced with the increase of the amount of inorganic substance.Specifically,the caloric value of briquette reduces by 16% comparing with raw coal,the exhalation rate of volatiles and ash content increases by 5% and 1.9%,respectively.Selecting Ayouqi coal with the sulfur content of 1.6% as raw coal,with the certain amount of sodium humic acid and the Ca/S molar ratio of 2:1,the sulfur retention efficiency of briquette has the highest value of 95% under the amount of limestone,slaked lime,sodium carbonate,sodium chloride and ferrous chloride is 2.0%,3.1%,1%,1% and 1%,respectively.2.Using coal gangue powder as additive,the sulfur retention performance of briquette was studied in the presence of certain amount of sodium humic acid.The sulfur retention rate could reach to 97% under the conditions that the limestone addition amount is 5%,slaked lime is 0.9% and coal gangue powder is 6%,Coal gangue has a better effect on the sulfur retention of briquette under high temperature.However the excessive use of coal gangue will cause bad influence on the combustion properties of briquette,ash content increases by 1% and calorific value decreases by 0.35 MJ / kg with the amount of coal gangue increases by 2%.3.Using clay and sodium humic acid as briquette binder and Achnatherum splendens as biomass additive,the bio-briquette was successfully prepared in the condition of choosing the coal with the low sulfur content and ash content as raw coal.The effects of briquette strength,ash content and volatile matter on the different addition of clay and Achnatherum splendens were investigated.The combustion characteristics and sulfur retention rate of Achnatherum splendens composited briquette were also analyzed,The results showed that the strength of briquette reaches to 339 N in the conditions that sodium humic acid,clay and achnatherum splendens is 8%,8% and 15%,respectively.Comparing with raw coal,the caloric value and ash content of briquette decrease by 1.7 MJ/kg and 4%,respectively.The exhalation rate of volatiles enhances by 6% in same condition.In addition,The results showed that the sulfur retention rate increases with the increase of the amount of Achnatherum splendens and the molar ratio of Ca/S when slaked lime is used as sulfur retention agent.The addition of slaked lime could improve the sulfur retention rate,which can be reached to 80% in the conditions that the amount of Achnatherum splendens is 15% and the Ca/S molar ratio is of 2:1.