Research On Clean Briquette Preparation And Pollutant Emission Control Based On Coke Powder

Coal briquette is a coal fuel with a certain mechanical strength prepared by using raw materials such as pulverized coal,binders,and sulfur-fixing agents through pressure molding.It can effectively improve the utilization efficiency of coal resources such as low-rank coal,improve combustion characteristics,and reduce coal pollution.emissions.This paper uses coke powder as the main raw material,supplemented by wheat straw,magnesium slag and other solid waste materials to prepare civil clean coal briquette.The coke powder has the characteristics of high fixed carbon,high calorific value,low volatile content and poor cohesiveness,so it is not suitable for direct civil use;the modified wheat straw pretreated with Na OH solution is used as the binder;magnesium slag and a small amount of Ca O are added as the fixed sulfur agent;mix the above raw materials and use a tablet machine to cold-press to prepare briquette.Through the orthogonal test,it is found that the amount of modified wheat straw is the most important factor affecting the compressive strength and falling strength.After comprehensive consideration,the optimal preparation process parameters of coke powder-biomass briquette are as follows:the amount of modified wheat straw is 20%,and the modified The temperature is 75℃,the concentration of Na OH is 2.0%,the amount of magnesium slag is 5%,the molding pressure is 25MPa,the amount of water added is 13%,and the pregelatinized starch is 1%.SEM and FTIR analysis showed that after the modification of wheat straw,some aromatic compounds and other viscous substances were dissolved on the surface,and intermolecular hydrogen bonds were widely formed;the exposure of internal fibers increased the mechanical meshing force between components,and the fibers Staggered winding can transmit the stress in the radial and axial directions;after the magnesium slag is activated,the surface vitreous structure is broken to produce viscous Na₂Si O₃;the hydrophilicity of the magnesium slag helps to fully infiltrate the coke powder and binder and maintain the intermolecular hydrogen the existence of the key.The composite binder can make the components in the briquette agglomerate tightly to form a firm skeleton structure,so that the briquette has good compressive strength and falling strength.TG-DTG analysis shows that the combustion process of coke powder-biomass briquette is divided into volatile combustion stage（first stage）and fixed carbon combustion stage（second stage）.level reaction.When the addition amount of wheat straw is 20%,the ignition temperature of briquette decreases to 516℃;the ignition index Z_i and the stable combustion index Z_c gradually increase,that is to say,wheat straw can improve the ignition and stable combustion characteristics of the briquette,and the burnout characteristic index Z_f gradually increases.reduce.The apparent activation energy required for the ignition of the volatiles in the first stage is185.0k J/mol;the activation energy required for the ignition of the fixed carbon in the second stage is 311.7k J/mol.The melting characteristic temperature of coke powder-biomass coal ash is between coke powder and wheat straw,and the ash deformation temperature is 1130℃when the straw addition amount is 20%respectively.A flue gas analyzer was used to measure and record the SO₂ emission concentration of coke powder-biomass briquette combustion,and the sulfur-fixing properties of non-sulfur-fixing agent,magnesium-slag sulfur-fixing agent,Ca O sulfur-fixing agent and composite sulfur-fixing agent were investigated respectively.The test results show that the peak SO₂ emission concentration of pure coke powder briquette is 6057mg/Nm³,and the coke powder-biomass briquette has excellent self-fixing sulfur capacity.Compared with the theoretical emission,the actual emission of SO₂ can be reduced by 45%when the addition of wheat straw is 20%.When adding 5%magnesium slag as sulfur fixer on the basis of adding 20%wheat straw,the peak concentration of SO₂ emission dropped to 474mg/Nm³;when adding Ca O with a Ca/S of 0.7,the peak concentration of SO₂ emission dropped to 123mg/Nm³.When adding Ca O with a Ca/S of 0.7 as a composite sulfur-fixing agent on the basis of 5%magnesium slag,the peak concentration of SO₂ emission was reduced to 18 mg/Nm³.