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英国硕士烘焙的技术经济评价Assignment范文

时间:2016-10-11 14:46来源:www.ukassignment.org 作者:Ayla Uslu 点击:
abstract摘要
 
预处理步骤具有生物能源链的性能有显著的影响,特别是在物流。烘焙,球团和热解技术,可在适度的尺度转化成生物质致密能源载体的便于运输和处理。烘焙是一个非常有前途的技术,由于相对于造粒(84%)和热解(64%)的高处理效率(94%)。1当焙干用制粒结合时,产物(TOP2)能量含量高达20.4 -22.7 GJ /吨。从拉丁美洲到鹿特丹港TOP交货的一次能源需求可能低至0.05 GJ / GJ,而相比之下,0.12 GJ / GJ的颗粒和0.08 GJ / GJHHV热解油。 TOP可以从现有的共烧植物递送到欧洲超过74的h /吨(3.3 H / GJ),电可制作廉价为4.4 hcent / kWhe。费舍尔Tropisch燃料成本6小时/ GJHHV为TOP,7小时/ GJ常规颗粒和9.5 H / GJHHV热解油。因此,来自TOP和常规粒料燃料生产是可比当前汽油生产成本为3〜7小时/ GJand柴油从2至7小时/ GJ,取决于油市场。3 HHV HHVThus,精心设计的供应链使国际从生物能源利用效率和经济的角度来看是可行的交易。与2008年保留爱思唯尔有限公司保留所有权利。The pre-treatment step has a significant influence on the performance of bioenergy chains, especially on logistics. Torrefaction, pelletisation and pyrolysis technologies can convert biomass at modest scales into dense energy carriers that ease transportation and handling. Torrefaction is a very promising technology due to its high process efficiency (94%) compared to pelletisation (84%) and pyrolysis (64%).1 When torrefaction is combined with pelletisation, the product (TOP2) energy content is as high as 20.4–22.7 GJ/ton. The primary energy requirement for TOP delivery from Latin America to Rotterdam harbour can be as low as 0.05 GJ/GJ, in contrast to 0.12 GJ/GJ for pellets and 0.08 GJ/GJHHV for pyrolysis oil. TOP can be delivered to Europe at over 74 h/ton (3.3 h/GJ) and electricity could be produced as cheap as 4.4 hcent/kWhe from an existing co-firing plant. Fisher Tropisch fuel costs 6 h/GJHHV for TOP, 7 h/GJ for conventional pellets and 9.5 h/GJHHV for pyrolysis oil. Consequently, fuel production from TOP and conventional pellets is comparable to the current gasoline production cost ranging from 3 to 7 h/GJand diesel from 2 to 7 h/GJ, depending on the oil market.3 HHV HHVThus, well designed supply chains make international trade of biomass feasible from energy efficiency and economic perspective. & 2008 Elsevier Ltd. All rights reserved. 
 
1. Introduction 介绍
 
Sustained energy supply is an essential objective to achieve and depends on ensuring secure and reliable energy sources. However, the European Union (EU) import dependency is rising. Unless domestic energy becomes more competitive in the next 20–30 years around 70% of the EU’s energy needs are expected to be met by imported products—some from regions threatened by insecurity [1]. On the other hand, fossil fuel consumption causes substantial environmental harm notably, climate change. Energy production and consumption account for 81.5% of the total green house gas (GHG) emissions in the EU-25 [2]. In addressing those threats, the EU is increasingly shifting towards policies favouring use of renewable energy sources. Currently biomass delivers around 4% of the EU’s primary energy (Eurostat) and in order to reach the future targets set out by the . Corresponding author at: Department of Science, Technology and Society, Copernicus Institute, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands. Tel.: +31 224212868; fax: +31 224291730. E-mail address: ayla.uslu@eea.europa.eu (A. Uslu). 1 Process efficiency includes sizing and drying of biomass. 2 TOP: torrefied and pelletised biomass. EU, significant amounts of biomass will be required. The renewable energy target in the EU’s overall mix is determined as 20% by 2020, which corresponds to 230–250 MtOE bioenergy depending on various assumptions [3].3 Furthermore as a substitute for transportation fuels, the EU set itself a minimum binding target of 10% biofuel use by 2020. Moreover, bioenergy contributes 22% of the primary energy supply in developing countries, and around 10% of global energy demand [4]. Since some countries have larger land areas used at lower densities compared to others, they may become net suppliers of renewable bioenergy. While biomass production costs in such countries may be relatively low, there will be additional logistic costs, energy uses and material losses [5]. However, several studies have given indications that international trade in biofuel could be economically feasible [6–8]. These studies, concerning long distance bio-energy transportation, analysed several cases to calculate biomass delivery and final energy production costs. Hamelinck developed a tool with which different bioenergy chains were analysed [5,6]. This work clarified that densification 3 The amount of bioenergy is dependent upon the total energy consumption growth, the increases in the other renewable energy sources and the end-use of the biomass. 0360-5442/$ -see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2008.03.007  
A. Uslu et al. / Energy 33 (2008) 1206–1223 prior to international transportation of biomass is crucial, as converting biomass into a densified intermediate can save transport and handling costs. In addition, it can improve the efficiency of the final conversion stage. Subsequently, pretreatment is a key step in the total supply chain. Broadly, feedstock costs contribute around 20–65% of the total delivery cost whereas pre-treatment and transport contribute 20–25% and 25–40%, respectively, depending on the location of the biomass resources [5]. However, recent and potential future improvements of pre-treatment technologies and their subsequent impacts on the overall bioenergy chain have not been addressed in detail. Currently, the state-of-the-art (SOTA) biomass-to-energy chains are mostly based on pelletisation. However, the pretreatment technologies such as fast pyrolysis and torrefaction may improve the economics of the overall production chain. However, these technologies are still under development and their economic and technical performances are unclear. There are no normalised data sets available in literature and the available information mainly discusses the technology and the intermediate products, rather than their influence on the performances of the whole production chains. The main objective in this study is therefore to assess which pre-treatment method(s), at what point of the chain, with which conversion technology (ies) would give the optimal power and fuel (syngas) delivery costs for international biomass supply chains. The study focuses on detailed techno-economic analysis of key pre-treatment technologies, namely torrefaction, pyrolysis and pelletisation and their respective impacts, in terms of costs and energy uses in various chains for biomass production and use. 
 
2. Methodology and evaluation criteria 方法和评价标准
 
A technology review was performed to collect design data of pre-treatment technologies. Mass yields, energy yields and process efficiencies of each technology were evaluated, partly by building simple models to determine energy and mass balances. The economic evaluation of the technologies was based on component level cost data, which were obtained from literature and personal communication with experts. Since the capacities of the components affect the specific cost of a plant, economies of scales were analysed. These were done by identifying the base scales, base costs and the maximum scales of the equipment. Next, the equipment costs for designed scales were calculated using the scale factors per component obtained from literature. Capital investment requirements4 and production costs were calculated, and subsequently a sensitivity analysis was performed to identify the most important parameters that influence the production costs. Cost data were normalised using the OECD deflator and exchange rates of national currencies. Following the techno-economic assessment of each pretreatment technology, several biomass-to-energy chains were designed depending on the location and scale of the technology applied. The chain assumptions were based on feedstock harvested in South America (Brazil) and the final conversion applied in North-West Europe. Final conversion technologies comprise Entrained Flow Gasification for Fischer Tropsch liquid (EF-FT) production, biomass integrated gasification combined cycle (BIGCC), SOTA combustion and co-firing for power production. An existing model and database developed by Hamelinck was used to design the chains [5,6]. This tool enables chains to be set up with harvesting, transport, storage, handling, pre-treatment and final conversion steps considered in many ways. It also calculates energy and mass balances and economic performances of the chains selected. Chain analyses were followed by sensitivity analyses to test the robustness of the study results and assess the variation in fuel/power costs. The performance and economic impacts of pre-treated biomass on final conversion stage was not studied in this research, as this requires an extensive technoeconomic analysis which could however be the focus of future research. 
 
3. Techno-economic evaluation 技术经济评价
 
3.1. Torrefaction 
Torrefaction is a thermal pre-treatment technology performed at atmospheric pressure in the absence of oxygen. Temperatures between 200 and 300 1C are used, which produces a solid uniform product with very low moisture content and a high calorific value compared to fresh biomass. Even though torrefaction is in its infancy, several studies show that torrefaction increases the energy density, hydrophobic nature and grindability properties of biomass [9–11]. Torrefied biomass typically contains 70% of its initial weight and 90% of the original energy content [9,11]. The moisture uptake of torrefied biomass is very limited, varying from 1% to 6%. 


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