基于生命周期评价的秸秆沼气集中供气工程能值分析

发布时间：2018-05-06 19:33

  本文选题：能值分析 + 生命周期评价　； 参考：《中国农业科学院》2016年博士论文

【摘要】：中国是农业大国,秸秆资源数量大、种类多、分布广。然而在农村地区,秸秆露天焚烧、废弃造成的大气污染、农业面源污染问题仍然存在。随着我国秸秆沼气技术的发展,秸秆沼气集中供气技术成为秸秆资源化利用的重要途径,是适应我国农村现阶段经济发展水平的实用技术,在秸秆资源丰富的农村地区得到推广和应用。实践表明,秸秆沼气集中供气技术,能够提高秸秆资源化利用效率,所产秸秆沼气可替代煤炭、液化气等化石能源,为农村提供优质、清洁的可再生能源,所产沼肥可用作有机肥。生物质资源在能源化生产和利用过程中也会消耗能量,排放污染物,因此对秸秆沼气集中供气工程的生态经济效益和环境影响进行科学合理的评价,对促进秸秆沼气的可持续发展具有重要意义。能值分析方法考虑了自然环境资源对系统经济发展做出的贡献,将投入系统的物质、能量、货币、劳务等不同种类、不同单位的生态流,转换成为太阳能值,将其作为统一的标准来衡量和分析,弥补了经济分析和传统能量分析的不足。本研究采用能值分析方法和生命周期评价方法对秸秆沼气集中供气工程的生态经济性和可持续性进行评价。主要结论分述如下:(1)对秸秆沼气集中供气工程投入资源的能量折算系数、能值转换率、污染物排放系数等进行考证分析并确定其取值。以15.83E+24sej/a能值基线为准,对秸秆沼气集中供气工程投入资源的能值转换率参数进行考证和分析。对玉米秸秆、小麦秸秆、农村劳动力的能值转换率进行核算,河南省安阳县小麦秸秆能值转换率、河北省青县玉米秸秆能值转换率和全国农村劳动力能值转换率,分别是1.10E+05sej/J、7.55E+04sej/J、2.56E+06sej/J。(2)以河南省安阳县西街村秸秆沼气集中供气工程为例,对非满负荷运行条件下秸秆沼气工程能值投入产出进行了定量核算和分析。结果表明,该秸秆沼气工程能值投入中,购买资源能值投入占99.73%,秸秆能值投入占73.83%。与满负荷运行相比,在非满负荷运行的情况下,沼气、沼渣沼液以及“三沼”的能值转换率皆有明显升高;工程的生态经济性、可持续发展性有所降低,环境负荷上升。要提高秸秆沼气集中供气工程的经济性、可持续性和环境外部性,必须努力实现工程的满负荷运行。(3)以河北省青县耿官屯秸秆沼气集中供气工程为例,根据沼渣沼液处理方式不同,将其设定为常规情景(情景1)、现实情景(情景2)和假设情景(情景3),进而对3种不同情景的能值投入、产出及其能值评价指标进行比较分析。结果表明,由情景1到情景3,购买不可更新资源能值占总投入的比重显著提升;从各子系统能值投入比重看,秸秆收集与预处理子系统显著下降,沼肥利用子系统显著升高,其他各子系统有所下降。常规情景下,青县耿官屯秸秆沼气集中供气工程沼气能值转换率为2.50E+05sej/J;随着沼渣沼液加工利用水平的提高,沼肥的能值转换率、“三沼”能值转换率呈下降的趋势;可更新能值率RER、可持续发展指数ESI、能值反馈率FYR和处理废弃物能力EWR都、环境负载率ELR等指标,随着产业链条延长和系统边界的变化,不再适用于生产工艺和产品方案调整前后的能值比较分析。(4)以河南省安阳县西街村秸秆沼气集中供气工程为例,以工程年产出沼气为功能单位,综合评估了秸秆沼气集中供气工程在全球变暖潜力、酸化潜力、气溶胶潜力、光化学烟雾潜力和人体毒性潜力5个方面的环境影响。将工程建设单元纳入秸秆沼气工程各生命周期边界,对工程建设单元、运行单元和产物利用单元的环境排放进行定量核算和分析。该秸秆沼气集中供气工程对全球环境的影响负荷为-137.72标准人当量,减排效果显著。煤炭增温和电力消耗是影响沼气工程环境排放的重要环节,选择低碳环保的沼气工程增保温方式和降低工程运行电耗是秸秆沼气集中供气工程工艺改进的重要内容。
[Abstract]:China is a large agricultural country with large number of straw resources, wide variety and wide distribution. However, in rural areas, straw burning in the open air, the air pollution caused by waste, and the problem of agricultural non-point source pollution still exist. With the development of straw biogas technology in China, the centralized gas supply technology of straw biogas has become an important way to utilize the straw resource, and it is adapted to our country. The practical technology of the rural economic development level in rural areas is popularized and applied in the rural areas with rich straw resources. The practice shows that the centralized gas supply technology of straw biogas can improve the utilization efficiency of straw resource, and the straw biogas can replace coal, liquefied gas and other fossil energy, and provide high quality and clean renewable energy for rural areas. The biogas fertilizer can be used as organic fertilizer. In the process of energy production and utilization, biomass resources will also consume energy and discharge pollutants. Therefore, the scientific and rational evaluation of the ecological and economic benefits and environmental effects of the straw biogas supply project is of great significance to the sustainable development of straw biogas. Considering the contribution of natural environmental resources to the development of the system economy, it will put into the system of material, energy, money, labor and so on, and convert the ecological flow of different units into solar value, and measure and analyze it as a unified standard, and make up for the shortage of economic analysis and traditional energy analysis. The method and life cycle evaluation method are used to evaluate the ecological economy and sustainability of the centralized gas supply project with straw biogas. The main conclusions are as follows: (1) the energy conversion coefficient, the conversion rate of energy value, the emission coefficient of the pollutants and the value of the pollutant emission coefficient are analyzed and determined. The results are as follows: (1) /a can be used to evaluate the conversion rate of the energy value of the corn straw, wheat straw and rural labor force, the conversion rate of wheat straw energy value in Anyang County, Henan Province, the conversion rate of maize straw energy value in Hebei province and the rural labor force in Qingxian County, Hebei province. The conversion rate of energy value is 1.10E+05sej/J, 7.55E+04sej/J, 2.56E+06sej/J. (2) taking the centralized gas supply project of Xi Jie Village Straw biogas in Anyang County of Henan Province as an example. The quantitative calculation and analysis of the energy input and output of the straw biogas engineering under the condition of unfilled load operation are carried out. The results show that the resources can be purchased in the energy input of the straw biogas project. The value input accounted for 99.73%, the energy input of the straw accounted for 73.83%. and the full load operation. Under the condition of the non full load operation, the energy conversion rate of the biogas, biogas slurry and the "three marsh" all increased obviously; the ecological economy, the sustainable development of the project and the environmental load increased. Economic, sustainable and environmental externalities, we must work hard to realize full load operation of the project. (3) taking the centralized gas supply project of gunguan straw biogas in Qingxian County, Hebei Province as an example, according to the different methods of biogas slurry treatment, it is set as a conventional scenario (scenario 1), realistic scenario (scenario 2) and hypothesis scenario (scenario 3), and then to 3 different scenarios The results show that from scenario 1 to scenario 3, the proportion of the non renewable resources to the total input is significantly increased. From the proportion of the energy input of the subsystems, the straw collection and pretreatment subsystem is significantly decreased, the biogas fertilizer utilization subsystem has been significantly increased, and the other subsystems are available. Under the normal situation, the conversion rate of biogas energy in the centralized gas supply project in gunguntun, Qingxian County, is 2.50E+05sej/J. With the improvement of the level of processing and utilization of biogas slurry, the conversion rate of the energy value of the biogas fertilizer, the conversion rate of the energy value of the "three marsh" is decreasing, the renewable energy value RER, the sustainable development index ESI, the energy value feedback rate FYR and the location of the energy value. EWR, environmental load rate ELR and other indexes, with the extension of industrial chain and the change of the system boundary, is no longer applicable to the comparison and analysis of the energy value before and after the adjustment of the production process and product scheme. (4) taking the centralized gas supply project of the straw biogas in the West Street Village of Anyang County, Henan as an example, the annual output of biogas in the project is used as a functional unit, and the comprehensive evaluation is made. The environmental effects of 5 aspects of global warming potential, acidification potential, aerosol potential, photochemical smog potential and human toxicity potential are estimated. The project construction unit is integrated into the life cycle boundary of straw biogas engineering, and the environmental emission of construction unit, operation unit and product utilization unit is carried out. Quantitative calculation and analysis. The impact load of the centralized gas supply project on the global environment is -137.72 standard human equivalent, and the effect of emission reduction is significant. The increase of coal energy consumption is an important link to influence the environmental emission of biogas engineering. The selection of the low carbon and environmental protection methane engineering heat preservation formula and the reduction of the power consumption of the project operation are the straw biogas set. The important content of process improvement of gas supply engineering.

【学位授予单位】：中国农业科学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S216.4
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本文编号：1853593