生物质精炼技术解决制浆厂现存瓶颈问题 第二部分:技术经济性评价

Bioref inery implementation for recovery debottlenecking at existing pulp mills Part Ⅱ :Techno-economic evaluation

对两种生物质精炼技术(黑液木素酸析沉淀分离技术,近中性条件下的半纤维素预抽提技术)的经济性评价进行了解释。采用WinGEMS软件绘制了制浆流程模型,用于计算质量和能量平衡。采用标准成本估测方法对投资成本、操作成本和两种生物质精炼技术的收益性进行了计算。结果显示:两种生物质精炼技术对所研究案例都有较好的经济性,并可以有效解决回收系统问题。根据评估可知,木素沉淀分离技术的税后内部回报率为95%,而半纤维素预抽提技术为28%。灵敏度分析表明:在所选择参数的灵敏度发生变化时,木素沉淀分离技术的税后内部回报率仍高于半纤维素预抽提技术。以税后内部回报率和成本额作为标准进行估测的结果表明:对所研究的浆厂而言,木素沉淀分离技术比近中性半纤维素预抽提技术更有前景。然而,对两种生物质精炼技术的评价还应该包括长期评估标准的比较。从木素沉淀工艺中分离得到的木素可以用于开发高附加值产品,或者用半纤维素预抽提液制取乙醇和醋酸,这些产品都应作为参考的指标,从而选择更合适的工艺技术。

The evaluation and process risk assessment of （a） lignin precipitation from black liquor, and （b） the near-neutral hemicellulose pre-extraction for recovery boiler debottlenecking in an existing pulp mill is presented in Part I of this paper, which was published in the July 2012 issue of TAPPI Journal. In Part II, the economic assessment of the two biorefinery process options is presented and interpreted. A mill process model was developed using WinGEMS software and used for calculating the mass and energy balances. Investment costs, operating costs, and profitability of the two biorefinery options have been calculated using standard cost estimation methods. The results show that the two biorefinery options are profitable for the case study mill and effective at process debottlenecking. The after-tax internal rate of return （IRR） of the lignin precipitation process option was estimated to be 95%, while that of the hemicellulose pre-extraction process option was 28%. Sensitivity analysis showed that the after tax-IRR of the lignin precipitation process remains higher than that of the hemicellulose pre-extraction process option, for all changes in the selected sensitivity parameters. If we consider the after-tax IRR, as well as capital cost, as selection criteria, the results show that for the case study mill, the lignin precipitation process is more promising than the near-neutral hemicellulose pre-extraction process. However, the comparison between the two biorefinery options should include long-term evaluation criteria. The potential of high value-added products that could be produced from lignin in the case of the lignin precipitation process, or from ethanol and acetic acid in the case of the hemicellulose pre-extraction process, should also be considered in the selection of the most promising process option.