调峰型LNG工厂碳排放核算及减排对策建议

Carbon emission accounting for peak-shaving LNG plant and suggestions on emission reduction countermeasures

[目的]“双碳”目标对LNG产业提出更高的降碳与环保要求,在此形势下,精准掌握LNG产业链碳排放水平,充分了解影响因素以制定切实可行的减排方案尤为重要。[方法]从典型的天然气液化工艺出发,采用生产系统-工业过程-排放设施3层分级的方法对调峰型LNG工厂的碳排放源进行识别与归类,分析了基本生产系统投入产出关系。在此基础上构建以碳平衡法为主、排放因子法为辅的碳排放动态核算体系,以弥补目前碳排放体系核算结果不精准、无法核算逃逸碳排放的问题。以中国某大型调峰型LNG工厂2022年实际生产运行情况为例,测算其全年碳排放量,分析碳排放结构与各排放源的影响因素。[结果]该工厂2022年碳排放总量为15.43×10^(4)t,液化过程碳排放强度为0.51tCO_(2)/tLNG,气化过程为1.37tCO_(2)/(10^(4)m^(3)),其中电力间接排放占比最高,达到66.95%,其次是燃料燃烧排放、工艺放空排放、火炬燃烧排放,分别占比18.42%、12.58%及1.79%,逃逸排放占比0.27%。[结论]针对该工厂的碳排放结构与强度特征,从应用冷能发电技术辅以外购绿色电力、实施节能减排措施进行节能改造、优化火炬系统密封气源并增设BOG作为燃料气系统补充气源、增加碳捕集回收利用装置等4个方面提出碳减排对策建议,为LNG产业的低碳化发展提供合理建议与参考方向。(图6,表6,参23)

[Objective]The“dual carbon”goals have heightened the demands for reducing carbon emissions and enhancing environmental protection within the LNG industry.To devise viable emission reduction solutions,it is crucial to precisely monitor the carbon emission levels throughout the LNG industry supply chain and comprehensively grasp the factors influencing them.[Methods]Following the typical natural gas liquefaction process,this study identified and categorized the carbon emission sources at peak-shaving LNG plants,utilizing a three-level classification method consisting of production systems,industrial processes,and emission facilities,and analyzed the input-output relationships within the basic production system.Based on the results,a dynamic carbon emission accounting system was established.This system primarily relies on the carbon balance approach,complemented by the emission factor method to tackle prevalent issues within the current carbon emission accounting system,such as inaccuracies in accounting outcomes and the absence of fugitive carbon emission evaluations.Subsequently,the proposed system was applied to a large peak-shaving LNG plant in China.The annual carbon emissions from the production and operation of this plant in 2022 were meticulously calculated.Furthermore,the carbon emission breakdown and the factors influencing various emission sources were thoroughly scrutinized.[Results]In 2022,the total carbon emissions of this plant amounted to 15.43×10^(4) t.The carbon emission intensity stood at 0.51 t CO_(2)/t LNG for the liquefaction process and 1.37 t CO_(2)/(10^(4) m^(3))for the gasification process.Indirect emissions from electricity constituted the largest share,reaching 66.95%,followed by emissions from fuel combustion,processes,and flare combustion,accounting for 18.42%,12.58%,and 1.79%respectively.Fugitive emissions made up 0.27%of the total emissions.[Conclusion]According to the carbon emission composition and intensity characteristics of this plant,suggestions for carbon emission reduction countermeasures are proposed from four aspects:(1)employing cold energy power generation technologies and purchasing green electricity as complementary sources;(2)implementing energy conservation transformations through energy conservation and emission reduction measures;(3)optimizing seal gas sources for the flare system,and utilizing Boil-off Gas(BOG)as an additional gas source for the fuel gas system;(4)deploying carbon capture and recycling facilities.These study outcomes provide logical recommendations and probable pathways for fostering the low-carbon advancement of the LNG industry.(6 Figures,6 Tables,23 References)