厨余垃圾烘焙-气化制氢模拟研究与和技术经济分析

Process simulation and exergy and techno-economic analysis of hydrogen production from kitchen waste by gasification integrated with torrefaction

烘焙是一种极具前景的厨余提质预处理手段,能显著提升后续气化合成气品质,但其技术经济可行性尚待评估。基于此,提出一种厨余烘焙-气化制氢工艺,并与直接气化制氢工艺比较,对2种工艺进行热力学分析和经济分析,评估其可行性。利用Aspen Plus研究了气化温度和水碳比(η)对厨余直接气化和烘焙-气化2种工艺制氢能力的影响。研究发现,温度和η提高了2种工艺的制氢能力,温度950℃,η为1.5~2.0为厨余直接气化和烘焙-气化工艺较理想的操作参数。通过分析[火用]效率和经济效益,对5.5万t/a含水率55%的厨余烘焙-气化制氢工艺进行综合评价,以探究该工艺的可行性。结果表明:引入烘焙预处理,总[火用]损增加813.2 kW,占整个工艺的10.5%。直接气化系统的[火用]效率为56.7%,烘焙-气化系统效率较直接气化提升2.8%。从经济角度分析,烘焙-气化设备总投资成本为512万美元,年运行成本为297万美元,最低H_(2)销售价格为2.94美元/kg,直接气化工艺最低H_(2)销售价格则升高9.5%。因此,厨余的烘焙-气化工艺制氢无论在热效率还是经济成本上相比直接气化更具优势。

Torrefaction is a promising pretreatment means for kitchen waste upgrading,which can significantly improve the quality of subsequent gasification syngas,but its economic feasibility is yet to be evaluated.Based on this,a process of hydrogen production from kitchen waste by steam gasification integrated with torrefaction(TG)was proposed in this study,compared to hydrogen production from food waste by steam direct gasification(DG),and thermodynamic and techno-economic assessments were fully conducted to assess the feasibility of the two processes.The effects of gasification temperature and steam to carbon ratio(η)on the hydrogen production capacity of two processes were investigated by using Aspen Plus.It is found that the hydrogen capacity of DG and TG is improved by increasing the temperature andη,and the optimal operating parameters are observed at temperature of 950℃andηof 1.5-2.0.Based on the simulation results,a comprehensive evaluation of the hydrogen production process was conducted by analysing exergy efficiency and economic benefits to explore the feasibility of the process at a plant size of 55000 wet tonnes/year with 55%water content.The energy and exergy results show that the introduction of torrefaction pretreatment results in an increase of 813.2 kW in total exergy loss,accounting for 10.5%of the overall process.The exergy efficiency of the DG is 56.7%.The exergy efficiency of TG is 2.8%higher than that of the DG.The economic analysis is suggested the total equipment cost is$5.12 million,the total annual production cost is$2.97 million and the minimum hydrogen selling price(M_(HSP))is$2.94/kg,while MHSP of DG is 9.5%higher.Therefore,TG has more advantages than DG in terms of thermal efficiency and economic cost.