以天然碱加工厂为研究对象,主体工艺流程采用"湿式分解—十水碱结晶—一水碱结晶—一水碱干燥—NaHCO3加工",供能工艺采用"燃煤热电联产+网电",构建了完整的天然碱加工厂碳排放核算方法.研究结果表明:天然碱加工厂产生的碳排放强度为622.16 kg CO2eq/t,其中直接碳排放强度为473.08 kg CO2eq/t,间接碳排放强度为180.28 kg CO2eq/t;碳汇减少的碳排放强度为31.20 kg CO2eq/t.针对天然碱加工厂碳排放高的情况,提出以下对策:增加天然碱矿石与溶采液接触时间来提高碱卤浓度,减少卤水蒸发量,降低天然碱蒸发结晶工艺对热量的需求,减少燃煤热电联产蒸汽量;选择高效设备和电机,实现电耗源头控制;强化室内试验,优化工艺参数;实施天然碱加工与新能源融合,提高绿电利用率,减少网电间接碳排放;适当提高NaHCO3产能,增加CO2回收利用量.
Carbon emission accounting and carbon emission reduction countermeasures for natural soda processing plants
With natural soda processing plants as the study subject,"wet decomposition+crystallization of sodium carbonate decahydrate+crystallization of sodium carbonate monohydrate+drying of sodium carbonate monohydrate+NaHCO3 production"was applied in the main process.The"cogeneration+grid electricity"was employed in the energy supply process.A complete carbon emission accounting method was constructed for the natural soda processing plant.According to the experiment result,the carbon emission intensity of natural soda processing is 622.16 kg CO2eq/t,with a direct carbon emission intensity of 473.08 kg CO2eq/t,the indirect carbon emission intensity of 180.28 kg CO2eq/t,and the carbon sinks-reduced carbon emission intensity of 31.20 kg CO2eq/t.In response to the high carbon emission of natural soda processing plants,countermeasures are proposed as follows.The contact time between natural soda ore and the solution is increased to improve alkali brine concentration,brine evaporation is reduced,the heat demand of natural soda evaporation and crystallization process is decreased,and the scale of coal-fired cogeneration is downsized.High-efficiency equipment and motors are selected to realize the control of electricity consumption at the source.The indoor test is strengthened and process parameters are optimized.Natural soda processing is integrated with new energy sources,the utilization rate of green power is improved and indirect carbon emissions from grid power are reduced.NaHCO3 production capacity is appropriately increased and CO2 recycling is enhanced.
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