Thermo-economic process model for thermochemical production of Synthetic Natural Gas (SNG) from lignocellulosic biomass

A detailed thermo-economic model considering different technological alternatives for thermochemical production of Synthetic Natural Gas (SNG) from lignocellulosic biomass is presented. First, candidate technology for processes based on biomass gasification and subsequent methanation is discussed and assembled in a general superstructure. Both energetic and economic models for biomass drying with air or steam, thermal pretreatment by torrefaction or pyrolysis, indirectly and directly heated gasification, methane synthesis and carbon dioxide removal by physical absorption, pressure swing adsorption and polymeric membranes are then developed. Performance computations for the different process steps and some exemplary technology scenarios of integrated plants are carried out, and overall energy and exergy efficiencies in the range of 69–76% and 63–69%, respectively, are assessed. For these scenarios, the production cost of SNG including the investment depreciation is estimated to 76–107 € MWh⁻¹_SNG for a plant capacity of 20 MW_th,biomass, whereas 59–97 € MWh⁻¹_SNG might be reached at scales of 150 MW_th,biomass and above. Based on this work, a future thermo-economic optimisation will allow for determining the most promising options for the polygeneration of fuel, power and heat.     

Thermo-economic analysis for the optimal conceptual design of biomass gasification energy conversion systems

This study addresses the thermo-economic assessment of a mid-scale (20 MW_th,wood) wood gasification, gas cleaning and energy conversion process, with particular attention given to electricity generation costs and tar control. Product distributions were estimated with a parametric stoichiometric equilibrium model calibrated using atmospheric air gasification data. A multi-objective optimisation problem was defined for a superstructure of alternative energy flow diagrams for each processing step. The trade-off between total investment costs and the exergy efficiency of electricity production was obtained, and analysed to identify operating conditions that minimise tar formation to prevent equipment fouling. The use of air, oxygen or steam fluidised bed gasifiers, closed coupled to an internal combustion engine combined cycle (ICE-CC) requiring cold gas cleaning, or gas turbine combined cycle (GT-CC) requiring hot gas cleaning have been considered. The operating conditions that maximise ICE-CC efficiency with cold gas cleaning (low pressure and high temperatures) also favour minimal tar formation. For GT-CC tar concentrations are higher, but this should not be of concern provided that hot gas cleaning can effectively prevent tar condensation. The trade-off appears to be optimal for steam gasification, with minimal specific costs of 2.1 €/W_e for GT-CC, and 2.7 €/W_e for ICE-CC. However, further calibration of the reaction model is still needed to properly assess product formation for other oxidants than air, and to properly take account of the impact of pressure on product distributions. For air gasification, the minimal specific cost of GT-CC is 2.5 €/W_e, and that of ICE-CC 3.1 €/W_e.     

H2 processes with CO2 mitigation: Thermo-economic modeling and process integration

Within the challenge of greenhouse gas reduction, hydrogen is regarded as a promising decarbonized energy vector. The hydrogen production by natural gas reforming and lignocellulosic biomass gasification are systematically analyzed by developing thermo-economic models. Taking into account thermodynamic, economic and environmental factors, process options with CO₂ mitigation are compared and optimized by combining flowsheeting with process integration, economic analysis and life cycle assessment in a multi-objective optimization framework. The systems performance is improved by introducing process integration maximizing the heat recovery and valorizing the waste heat. Energy efficiencies up to 80% and production costs of 12.5–42 $/GJH₂${\text{GJ}}_{{\text{H}}_2}$ are computed for natural gas H₂ processes compared to 60% and 29–61 $/GJH₂${\text{GJ}}_{{\text{H}}_2}$ for biomass processes. Compared to processes without CO₂ mitigation, the CO₂ avoidance costs are in the range of 14–306 $/tCO_2,avoided${\text{t}}_{{\text{CO}}_2,\text{avoided}}$. The study shows that the thermo-chemical H₂ production has to be analyzed as a polygeneration unit producing hydrogen, captured CO₂, heat and electricity.     

我国发展生物质液体燃料的探讨

从我国发展生物质液体燃料的重要性出发，通过对我国生物质液体燃料资源情况以及乙醇作为车用燃料使用的动力性、经济性、使用中的特殊性(对发动机冷起动、气阻、产生液膜的影响)及安全性(乙醇的毒性、对人体、生态的影响，乙醇的安全性、在使用过程中的排放等)进行了较为全面、详细的分析，提出应大力开展生物质液体燃料的基础研宄工作．     

Conversion of carbon dioxide and methane in biomass synthesis gas for liquid fuels production

The premise of this research is to find whether methane (CH₄) and carbon dioxide (CO₂) produced during biomass gasification can be converted to carbon monoxide (CO) and hydrogen (H₂). Simultaneous steam and dry reforming was conducted by selecting three process parameters (temperature, CO₂:CH₄, and CH₄:steam ratios). Experiments were carried out at three levels of temperature (800 °C, 825 °C and 850 °C), CO₂:CH₄ ratio (2:1, 1:1 and 1:2), and CH₄:steam ratio (1:1, 1:2 and 1:3) at a residence time of 3.5 × 10³ g_cat min/cc using a custom mixed gas that resembles biomass synthesis gas, over a commercial catalyst. Experiments were conducted using a Box-Behnken approach to evaluate the effect of the process variables. The average CO and CO₂ selectivities were 68% and 18%, respectively, while the CH₄ and CO₂ conversions were about 65% and 48%, respectively. The results showed optimum conditions for maximum CH₄ conversion was at 800 °C, CO₂:CH₄ ratio and CH₄:steam ratios of 1:1.     

Thermo-economic optimisation of the integration of electrolysis in synthetic natural gas production from wood

Converting wood to grid quality methane allows to distribute a CO₂ free, renewable energy resource in a conventional energy distribution system and use it in transportation applications. Applying a multi-objective optimisation algorithm to a previously developed thermo-economic process model for the thermochemical production of synthetic natural gas from wood, the present paper assesses the prospect of integrating an electrolyser in conversion systems based on directly and indirectly heated gasification. Due to an inherent lack of hydrogen for complete conversion of wood into methane and the possibility for rational use of oxygen, it is shown that electrolysis is an efficient and economically interesting option for increasing the gas output of the process while storing electricity and producing fuel that mitigates CO₂ emissions.     

生物质热化学过程制氢技术

生物质是世界上最丰富的可再生资源之一,氢能源是未来理想的能源载体.生物质生长周期短,产量巨大,作为能源利用时,其CO2排放量几乎为零,因此被视为非常有潜力的清洁能源之一.生物质制氢技术主要包括热化学过程和生物过程,其中热化学过程主要是将生物质气化或生成生物油,再进行重整和水气置换反应,从而获得较高产量的氢气.文章介绍了利用生物质热裂解和气化(包括超临界水条件下气化)制氢技术,并对其未来的发展做了展望.     

Catalytic deoxygenation of liquid biomass for hydrocarbon fuels

Liquid biomass such as methyl laurate and canola oil is deoxygenated with hydrogen and NiMo/γ-Al₂O₃ catalyst. Oxygen from methyl laurate and canola oil is removed at 18.25–85.13 bar initial cold hydrogen pressure and 300–400 °C, using a 316 stainless steel batch reactor. Removal of oxygen from liquid methyl laurate and canola oil is evaluated with a GC/MS analyzer for liquid reaction products and another GC for gaseous reaction products. The range of reaction duration of liquid biomass in the batch reactor is 30–60 min under the deoxygenation conditions. Conversion of liquid biomass into gaseous products is evaluated with analysis data of gas products and a mass balance in terms of hydrogen.The objective of this research is to develop an efficient method of removing oxygen from liquid biomass to produce petroleum-comparative liquid hydrocarbons with hydrogen and a catalyst.Removal of oxygen from bio-based fuels for liquid hydrocarbon fuel is needed to increase its energy intensity, stability, and decrease its viscosity. In this paper, removal of oxygen from methyl laurate and canola oil is discussed in detail in terms of various oxygen removal conditions such as reaction temperature and pressure, catalyst amount, and hydrodynamics of heterogeneous reaction mixture in the batch reactor.     

Assessment of coal and biomass to liquid fuels in central Appalachia,USA

Liquid fuels from coal and biomass have the potential to reduce petroleum fuel consumption and CO₂ emissions. A multi‐equation model was developed to assess the economics of a potential coal/biomass‐to‐liquids (CBTL) fuel plant in the central Appalachian hardwood region, USA. The model minimizes the total annual production cost subject to a series of regional supply, demand, and other constraints. Model inputs include coal and biomass availability, biomass handling system, plant investment, production capacity, transportation logistics, and project financing. The outputs include the required selling price (RSP) and the optimal logistical decision‐making associated with feedstock requirement, collection, delivery, and liquid fuel production. Results showed that the RSP of Fischer–Tropsch (FT) diesel for a 40 000 barrel‐per‐day CBTL plant with coal/biomass ratio (by weight) of 85/15 was $86.45–87.25 bbl^?1 using different biomass handling systems. The RSP would vary between $86.45 and $89.81 per barrel according to different coal/biomass mix ratios. In consideration of the carbon offset credits due to the addition of biomass, the RSP was adjusted to $84.19–86.74 with respect to four levels of carbon prices. Sensitivity analyses indicated that the RSP of FT diesel was mostly affected by plant capacity, capital cost, coal price, and liquid fuel yield. The crude‐oil‐equivalent price of FT fuels must be above $66 bbl^?1 for a CBTL plant to be profitable in central Appalachia for the long run. These results can help investors/decision‐makers evaluate future CBTL developments in the region. Copyright © 2011 John Wiley & Sons, Ltd.     

生物质燃料固化成型环模参数化设计

我国在生物质燃料成型机的设计理论研究方面已经取得了很大的进步,但仍存在生产效率偏低、能耗偏高等缺点。参数化设计是利用先进的参数化设计软件Pro/Engineer优化参数,研究环模的力学特性,找到最佳的成型参数,建立环模的理想模型,计算相关结构参数,分析环模结构参数对生产效率、成型品质和成型机稳定性的影响。参数化设计可大大节约设计时间,增加模型的利用率,优化设计,加快环模成型机的产业化进程。     

几种生物质颗粒燃料等温燃烧过程和动力学研究

对4种华北地区生物质颗粒燃料进行等温燃烧失重试验.由试验数据曲线拟合得到了拟合方程,求解出活化能E、反应级数n、频率因子A.结果表明,生物质颗粒燃料在750～950℃温度下等温燃烧过程的反应级数为2～3.     

生物质热解制炭与制气一体化研究

在自行设计的管式炉上进行生物质热解制炭与制气一体化研究,对生物质种类和热解终温两个因素进行了实验和分析,得到了生物质热解过程中气体析出的规律和固体炭的产率。当以制炭和制气一体化为目的,在4种生物质原料中选用麦秆,热解终温选择500℃时,可以得到较大的固体炭产率和气体析出浓度。     

Emissions from sawdust biomass and diesel blends fuels

Biomass producer gas presents a very promising alternative fuel to diesel since it is a renewable and clean burning fuel having similar properties to those of diesel. In this outline, a multi-cylinder diesel engine is experimentally optimized for maximum diesel savings, lower emissions, and without any excessive vibration of the engine using sawdust biomass as producer gas. Emission parameters of the double-fuel engine at diverse gas flow rates are contrasted with those of diesel at distinctive load conditions. The study brings out that the greatest diesel reserve happens to be 80% at 8 kW load without any engine issue in dual-fuel mode. Carbon monoxide (CO), hydrocarbon (HC), and carbon dioxide (CO₂) emissions in dual-fuel mode are more contrasted with diesel at all test extents. Smoke opacity and oxide of nitrogen (NO) emission values in dual-fuel mode are less contrasted with diesel.     

Co-production of synthetic fuels and district heat from biomass residues,carbon dioxide and electricity: Performance and cost analysis

Large-scale systems suitable for the production of synthetic natural gas (SNG), methanol or gasoline (MTG) are examined using a self-consistent design, simulation and cost analysis framework. Three basic production routes are considered: (1) production from biomass via gasification; (2) from carbon dioxide and electricity via water electrolysis; (3) from biomass and electricity via hybrid process combining elements from routes (1) and (2). Process designs are developed based on technologies that are either commercially available or successfully demonstrated at precommercial scale. The prospective economics of future facilities coproducing fuels and district heat are evaluated from the perspective of a synthetic fuel producer. The levelised production costs range from 18–37 €/GJ for natural gas, 21–40 €/GJ for methanol and 23–48 €/GJ for gasoline, depending on the production route. For a given end-product, the lowest costs are associated with thermochemical plant configurations, followed by hybrid and electrochemical plants.     

Thermogravimetric analysis and process simulation of oxy‐fuel combustion of blended fuels including oil shale,semicoke, and biomass

Oxy‐fuel (OF) combustion is considered as one of the promising carbon capture and storage technologies for reducing CO₂ emissions from power plants. In the current work, the thermal behaviour of Estonian oil shale (EOS) and its semicoke (SC), pine saw dust, and their blends were studied comparatively under model air (21%O₂/79%Ar) and OF (30%O₂/70%CO₂) conditions using thermogravimetric analysis. Mass spectrometry analysis was applied to monitor the evolved gases. The effect of SC and pine saw dust addition on different combustion stages was analysed using kinetic analysis methods. In addition, different co‐firing cases were simulated using the ASPEN PLUS V8.6 (APV86) software tool to evaluate the effects of blending EOS with different biomass fuels of low and high moisture contents. The specific boiler temperatures of each simulated case with the same adjusted thermal fuel input were calculated while applying the operation conditions of air and OF combustion. According to the experiment and process simulation results, the low heating value and high carbonate content of SC brings along endothermic decomposition of carbonates, which negatively affects the heat balance during the conventional co‐combustion of EOS with SC. Instead, firing of EOS with SC and biomass in OF process can be an effective solution to reduce the environmental impact in terms of the reduction of CO₂ emissions and ash. Furthermore, the sensible heat from SC can positively affect the energy balance of the system as the endothermic effect of decomposition of CaCO₃ (for both EOS and SC) can be avoided in OF combustion.     

A novel integrated process for hydrogen production from biomass

A novel process, which integrated with biomass pyrolysis, gas–solid simultaneous gasification and catalytic reforming processes, was utilized to produce hydrogen. The effects of gasification temperature and reforming temperature on hydrogen yield and carbon conversion efficiency were investigated. The results showed that both higher gasification temperature and reforming temperature led to higher hydrogen yield and carbon conversion efficiency. Compared with the two-stage pyrolysis-catalytic reforming process, hydrogen yield and carbon conversion efficiency were greatly increased from 43.58 to 75.96 g H₂/kg biomass and 66.18%–82.20% in the integrated process.     

Thermo-economic and thermo-environmental assessment of hydrogen production,an experimental study

Nowdays, the topic involvement of green hydrogen in energy transformation is getting attention in the world. The current research examined, thermo-economic and thermo-environmental analyses of the organic Rankine cycle (ORC) system and the hydrogen production system integrated into the solar collector with medium temperature density are investigated. The presented study is a holistic evaluation of experimentally solar-assisted electricity and hydrogen production. The studied model is comprised of an evacuated tube solar collector for thermal energy generation, ORC system for electricity generation and proton exchanger membrane electrolyzer (PEMe) for hydrogen production. According to the results of the thermodynamic analysis, the energy and exergy efficiency of the whole system are calculated as 39.01% and 17.37%, respectively. Also exergoenviroeconomic and exergoenviromental analysis of the whole system is found as 71.48 kgCO₂/kWh and 0.139 $/kgCO₂, respectively. In addition, the sustainability index of the presented system is obtained as 1.21. In this study, in addition to thermodynamic analysis, parameters such as energy and exergy affecting environmental and economic efficiency, are explained. Ambient temperature plays a prominent role in energy-based environmental analysis. On the contrary, the ambient temperature did not cause a significant change in the exergy-based environmental analysis.     

Pollutants from the combustion of solid biomass fuels

This review considers the pollutants formed by the combustion of solid biomass fuels. The availability and potential use of solid biofuels is first discussed. This is followed by the methods used for characterisation of biomass and their classification. The various steps in the combustion mechanisms are given together with a compilation of the kinetic data. The chemical mechanisms for the formation of the pollutants: NOx, smoke and unburned hydrocarbons, SOx, Cl compounds, and particulate metal aerosols are outlined. Examples are given of emission levels of NOx and particulates from combustion in fixed bed combustion, fluidised bed combustion and pulverised biomass combustion and co-firing. Modelling methods for pollutants are outlined. The consequential issues arising from the wide scale use of biomass and future trends are then discussed.     

生物质制取车用燃料的综合性能评价

针对生产规模为5万t/a的生物质气化合成二甲醚系统和生物质热解加氢提质制汽油柴油系统,基于生命周期评价方法,结合层次分析法建立了新的环境-经济综合性能评价模型,分别对两个系统的环境性、经济性和综合性能指标进行分析对比。结果表明:在全球性视角下的环境负荷最大;全球变暖、酸化和光化学污染是主要的环境影响类型;生长阶段、生产阶段和消费阶段对环境影响的作用最大;设计工况下两个系统在全球性、区域性、局地性视角下的综合性能指标分别为3.98,3.16,2.04(人·a)/万元和6.31,5.89,4.84(人·a)/万元,对比可见生物质气化合成二甲醚系统产生每万元经济收益的环境影响更低,故综合性能更好。