CFB Boiler Blended With Environmental Slime Briquette System Design And Application Analysis In Thermal Power Plant

Slime because of high moisture content, strong stickiness and easy get together to beagglomeration when it burns. So it has been used as a low-grade fuel and difficult to behigh-volume used in industry. Circulating fluidized bed combustion technology become theprimary way to solve the bulk use of slime resource utilization; among them, the way ofusing coal slurry pumped to send it to the top of the combustion chamber has beensuccessfully used, but the equipment of this method costs high investment, high maintenance,and the thermal efficiency is low. Circulating fluidized bed boiler in most power plants usefurnace dry desulfurization, so the desulfurizer elutriation and entrainment problem is serious.In this context, this paper brings up that mixing the coal slime and meticulous desulfurizationagent to make low intensity mixing coal briquette, send them into circulating fluidized bedboiler directly. Then, extending meticulous desulfurization furnace residence time andimproving the desulfurization efficiency to seek more cost-effective way of slime combustionFirstly, this paper designs and selects the environmental slime briquette blending system.The system includes slime conveying, crushing, mixing, pressing briquettes, coal shedheating antifreeze and other major equipment. Among them, the slime uses the transportationmethods of wide leather belts tied and low rotation rate. The material handling needsdetermines the belt roller speed to be2.64r/h to solve the conveyor belt slippage problem.Crushing the slime and meticulous desulfurization agent particles by using differential speeddouble roll crusher and secondary crusher horizontal shaft mixer. To ensure that the materialsegregation phenomenon does not occur, determines the maximum roller speed to be30r/min.Determine the size of the mixer according to the material throughput. According to a smaller briquette size demand and lower molding pressure, choose the roll coal briquette equipmentto manufacture briquette. According to the roller control principle, calculated the motorpower and the relative sizes. Depending on the cycle gas turbine’s power separation principle,design thickness sorbent particle sorting device. Slime shed using the way of waste steamheat and uniform heating air duct, the speed of the wind is6m/s. So the opening area of theoutlet is0.14m2, the air supply is30370Nm3/h, the exit velocity of the selected air curtaindoor is8m/s and the width of the outlet is0.63m.Secondly, based on the effect of water content and shape to determine the proportion ofslime and meticulous preparation desulfurizer is2:1. Determine the optimum blending ratioof23.66%based on desulfurizer entirely from environmentally friendly coal slime. Under thepremise of ensuring the normal and stable operation of the unit, do industrial co-firing test inShanxi some power plant2×50MW circulating fluidized bed unit, and analyze itsdesulfurization and operational characteristics. The result shows that the average ratio of thedesulfurization efficiency is1.88%higher than without blending with environmental slimebriquette, the annual average concentration of SO2emissions decreased from246.7mg/Nm3to155.9mg/Nm3, meet the new requirements of environmental emissions. When the blendingratio is less than35%and the bed temperature was above800℃, can achieve stablecombustion When the blending ratio is23.66%, experimental data and theoretical calculationshows that after blending with green slime coal, the mean fly ash of the unit taking up thetotal share increased2.8%ash, the mean bottom slag carbon content is0.06%higher thannon-blended environmental slime coal, the average ratio of carbon content in fly ash is0.93%higher than without blending with environmental slime coal.Finally, analysis the boiler thermal efficiency and economy after blending withenvironmental slime briquette. Calculating how does the moisture affect the calorific value ofthe fuel, the result shows that moisture content of20%per kilogram of slime combustion heatdirectly waste about534.7kJ. When Ca/S ratio was2.3and the desulfurization efficiency was90%, each drawn into1mol CaCO3, the desulfurization chemistry emit heat is6.54kJ. When the blending ratio was23.66%, different load boiler thermal efficiency is lower than thedesign value of the average2.11%. The boiler thermal efficiency in THA conditions is2.06%lower than without blending with environmental slime briquette. Among them, heat losses is1.47%higher and solid incomplete combustion heat losses is0.57%higher than withoutblending with environmental slime briquette. Calculated in according to the existing coalprice mix of fuel per ton,the result shows that the electricity costs could be reduced if it was6yuan cheaper than the original coal gangue, while fuel prices are translated mixed coalgangue per ton was32yuan lower than the original coal gangue, and the economic benefitwas obviously. This paper provides some guidance for the subsequent burning utilization ofslime and other crew blended with environmental slime briquette, points out deficiencies inthe project plan and the problems to be solved in following studies. It also provides somedesign ideas and practical application experience for taking large circulating fluidized bedcombustion unit with slime to generate electricity.