Chlorine element metabolism and regulation during the incineration process of textile dyeing sludge
The high calorific value of textile dyeing sludge makes it suitable for incineration cogeneration,which has a positive carbon reduction effect.However,due to industry-specific characteristics,high chlorine content in textile dyeing sludge poses new technical challenges for safe boiler operation and achieving ultra-low emission of flue gas.Quantitatively revealing the composition and migration characteristics of chlorine elements during the incineration process of printing and dyeing sludge,and conducting refined management of chlorine substance flow,holds significant practical value.Based on a typical engineering case of 2 500 t·d-1 textile dyeing sludge drying-incineration cogeneration,this study established a chlorine element mass flow analysis model based on minimal process units and focused on analyzing key process stages such as drying,incineration,dedusting,and desulfurization through measurements and online monitoring.This study illustrated the comprehensive chlorine element migration and metabolism patterns throughout the entire process,identifying critical nodes for chlorine substance flow management.The study results showed that:1)The chlorine content of the sludge fed into the incinerator ranged from 1.4 to 2.4 mg·kcal-1(on a lower heating value basis,chlorine-specific),which surpassed the average chlorine content in coal for coal-fired power plants by a factor of 14.6;2)The initial hydrogen chloride concentrations in the flue gas were found to be between 170 to 250 mg·Nm-3,markedly exceeding the levels typically recorded in coal-fired power plants by two to five fold;3)The implementation of an innovative dual-tower,dual-loop wet flue gas desulfurization technique had been shown to substantially decrease the hydrogen chloride concentration in the flue gas to below 5 mg·Nm-3,thus enabling the attainment of ultra-low emission standards.Building on its findings,the study posited two primary strategies to enhance chlorine material flow management in sludge-to-energy processes.The first strategy emphasized the need for rigorous monitoring of chlorine concentrations in sludge destined for incineration.It suggested that when chlorine levels exceed 3 700 mg·kg-1,the admixture of municipal sludge can effectively adjust the input chlorine levels,ensuring boiler safety.The second strategy recommended stringent control of chloride ion concentrations within flue gas desulfurization and denitration systems.It advised maintaining chloride ion concentrations in the scrubber fluid below 20 000 mg·L-1.These recommendations offer practical guidelines for refining sludge incineration practices for resource recovery.
textile dyeing sludgeincineration of industrial sludgechlorine metabolismmaterial flow managementultra-low emissions
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