Chemicals, Energy, and Biomaterials from Agricultural Waste Resources in South China

Owing to its subtropical or tropical environment and climate,South China is home to unique agricultural crops such as sugar cane,pineapple,banana,cassava,and rice,which generate a large amount of lignocellulosic agricultural wastes during agricultural as well as associated industrial processing.The efficient utilization of these wastes will have a significant impact on the economy and sustainable development of South China.This paper reviews the research investigations conducted both in China and elsewhere on the conversion of wastes from these subtropical or tropical agricultural crops into useful chemicals,energy,and biomaterials.The goal of this paper is to promote and summarize the extensive investigations on these agricultural wastes for the development of biorefinery.     

Economic Assessment of Supercritical CO2 Extraction of Waxes as Part of a Maize Stover Biorefinery

To date limited work has focused on assessing the economic viability of scCO₂ extraction to obtain waxes as part of a biorefinery. This work estimates the economic costs for wax extraction from maize stover. The cost of manufacture (COM) for maize stover wax extraction was found to be €88.89 per kg of wax, with the fixed capital investment (FCI) and utility costs (C_UT) contributing significantly to the COM. However, this value is based solely on scCO₂ extraction of waxes and does not take into account the downstream processing of the biomass following extraction. The cost of extracting wax from maize stover can be reduced by utilizing pelletized leaves and combusting the residual biomass to generate electricity. This would lead to an overall cost of €10.87 per kg of wax (based on 27% combustion efficiency for electricity generation) and €4.56 per kg of wax (based on 43% combustion efficiency for electricity generation). A sensitivity analysis study showed that utility costs (cost of electricity) had the greatest effect on the COM.     

A multiobjective optimization framework for design of integrated biorefineries under uncertainty

A systematic approach for development of a reliable optimization framework to address the optimal design of integrated biorefineries in the face of uncertainty is presented. In the current formulation, a distributed strategy which is composed of different layers including strategic optimization, risk management, detailed mechanistic modeling, and operational level optimization is applied. In the strategic model, a multiobjective stochastic optimization approach is utilized to incorporate the tradeoffs between the cost and the financial risk. Then, Aspen Plus models are built to provide detailed simulation of biorefineries. In the final layer, an evolutionary algorithm is employed to optimize the operating condition. To demonstrate the effectiveness of the framework, a hypothetical case study referring to a multiproduct lignocellulosic biorefinery is utilized. The numerical results reveal the efficacy of the proposed approach; it provides decision makers with a quantitative analysis to determine the optimum capacity plan and operating conditions of the biorefinery. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3208–3222, 2015     

SO2-Ethanol-Water (SEW) Pulping: I. Lignin Determination in Pulps and Liquors

Abstract

Quantitative determination of lignin in SO₂-ethanol-water (SEW) pulps and spent liquors is described. The methods developed for conventional sulfite pulping are successfully applied to the SEW process. Linear correlations between Klason/total lignin content and kappa number are found over a wide pulp yield range for spruce, beech, and wheat straw. Lignin content of the spruce spent SEW liquors is determined using either hydrogen peroxide to remove SO₂ and dilution by 3% sulfuric acid or simply by dilution with 0.1M sodium hydroxide. The recommended wavelength is 280 nm. The experimentally found values for the extinction coefficient of dissolved lignin in 3% sulfuric acid and in 0.1M NaOH are 19 and 23 L/(g·cm), respectively. The interference of furanic compounds is eliminated by reduction with sodium borohydride.     

Optimal processing pathway selection for microalgae-based biorefinery under uncertainty

We propose a systematic framework for the selection of optimal processing pathways for a microalgae-based biorefinery under techno-economic uncertainty. The proposed framework promotes robust decision making by taking into account the uncertainties that arise due to inconsistencies among and shortage in the available technical information. A stochastic mixed integer nonlinear programming (sMINLP) problem is formulated for determining the optimal biorefinery configurations based on a superstructure model where parameter uncertainties are modeled and included as sampled scenarios. The solution to the sMINLP problem determines the processing technologies, material flows, and product portfolio that are optimal with respect to all the sampled scenarios. The developed framework is implemented and tested on a specific case study. The optimal processing pathways selected with and without the accounting of uncertainty are compared with respect to different objectives.     

Framework for margins-based planning: Forest biorefinery case study

The biorefinery concept offers a promising solution to transform the struggling forestry industry. Not only will the implementation of new products and processes help to diversify revenues, it will also offer an opportunity to change the manufacturing culture by better managing the flexibility of assets to react to volatile market conditions. In this paper, an integrated supply-chain planning framework is presented. It is based on optimizing a superstructure to help decision makers identify different supply-chain policies to adapt to different market conditions. It integrates revenue management concepts, activity-based cost accounting principles, manufacturing flexibility and supply-chain flexibility in a tactical model to maximize profit in a price-volatile environment. A case study of a newsprint mill implementing a parallel biomass fractionation line producing several biochemicals is used to illustrate this approach. Results and benefits are presented for the traditional pulp and paper business and for the transformed biorefinery in different market scenarios.     

Pyrolysis of Banana and Coffee Residues after Acid Hydrolysis

The use of the residues from renewable feedstock, besides the production of fuels, but also for the generation of other chemicals products, has become a priority. Superior plants have considerable potential as carbohydrate, aryl and fatty acids sources. However, the separation of the main constituents of the samples is necessary for several purposes in the biorefinery concept. The acid hydrolysis and pyrolysis processes are very promising technology, however, some adjustments in the conditions of pyrolysis are needed for different biomasses since carbohydrates were detected （14%-17%） in the residues after the conventional acid hydrolysis of these uncommon biomasses （coffee husk and banana stem and stalk）. On the other hand, it was showed that, by pyrolysis, it is possible to obtain from the solid residue after acid hydrolysis： pyrogenic carbon （charcoal with a yield of 48.5%-52.7%） for agriculture use （biochar） and valuable chemicals in the pyrolysis oil biooil fraction （that accounted by 26.4%-29.0%, free of water）, such as lignin monomers （32.6%-56.4% of the bio-oil） and fatty acids （30%-52.5%）.     

Sustainable design and synthesis of algae‐based biorefinery for simultaneous hydrocarbon biofuel production and carbon sequestration

The superstructure optimization of algae‐based hydrocarbon biorefinery with sequestration of CO₂ from power plant flue gas is proposed. The major processing steps include carbon capture, algae growth, dewatering, lipid extraction and power generation, and algal biorefinery. We propose a multiobjective mixed‐integer nonlinear programming (MINLP) model that simultaneously maximizes the net present value (NPV) and minimizes the global warming potential (GWP) subject to technology selection constraints, mass balance constraints, energy balance constraints, technoeconomic analysis constraints, and environmental impact constraints. The model simultaneously determines the optimal decisions that include production capacity, size of each processing unit, mass flow rates at each stage of the process, utility consumption, economic, and environmental performances. We propose a two‐stage heuristic solution algorithm to solve the nonconvex MINLP model. Finally, the bicriteria optimization problem is solved with ε‐constraint method, and the resulting Pareto‐optimal curve reveals the trade‐off between the economic and environmental criteria. The results show that for maximum NPV, the optimal process design uses direct flue gas, a tubular photobioreactor for algae growth, a filtration dewatering unit, and a hydroprocessing pathway leading to 47.1 MM gallons of green diesel production per year at $6.33/gal corresponding to GWP of 108.7 kg CO₂‐eq per gallon. © 2013 American Institute of Chemical Engineers AIChE J, 59: 1599–1621, 2013     

葡萄酒泥高价值产物开发及生物炼制研究概况

文章综述了葡萄酒泥中具开发潜力的高价值产物研究,以及可实现酒泥全面利用的生物炼制研究概况,分析了限制中国葡萄酒泥工业化开发利用的原因并提出了建议。