Energy optimization of bioethanol production via gasification of switchgrass

In this article, we address the conceptual design of the bioethanol process from switchgrass via gasification. A superstructure is postulated for optimizing energy use that embeds direct or indirect gasification, followed by steam reforming or partial oxidation. Next, the gas composition is adjusted with membrane‐PSA or water gas shift. Membrane separation, absorption with ethanol‐amines and PSA are considered for the removal of sour gases. Finally, two synthetic paths are considered, high alcohols catalytic process with two possible distillation sequences, and syngas fermentation with distillation, corn grits, molecular sieves and pervaporation as alternative dehydration processes. The optimization of the superstructure is formulated as an mixed‐integer nonlinear programming problem using short‐cut models, and solved through a special decomposition scheme that is followed by heat integration. The optimal process consists of direct gasification followed by steam reforming, removal of the excess of hydrogen and catalytic synthesis, yielding a potential operating cost of $0.41/gal. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Multiobjective optimization under uncertainty of the economic and life‐cycle environmental performance of industrial processes

The combined use of multiobjective optimization and life‐cycle assessment (LCA) has recently emerged as a useful tool for minimizing the environmental impact of industrial processes. The main limitation of this approach is that it requires large amounts of data that are typically affected by several uncertainty sources. We propose herein a systematic framework to handle these uncertainties that takes advantage of recent advances made in modeling of uncertain LCA data and in optimization under uncertainty. Our strategy is based on a stochastic, multiobjective, and multiscenario mixed‐integer nonlinear programming approach in which the uncertain parameters are described via scenarios. We investigate the use of two stochastic metrics: (1) the environmental impact in the worst case and (2) the environmental downside risk. We demonstrate the capabilities of our approach through its application to a generic complex industrial network in which we consider the uncertainty of some key life‐cycle inventory parameters. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2098–2121, 2014     

Targeting climate-neutral hydrogen production: Integrating brown and blue pathways with green hydrogen infrastructure via a novel superstructure and simulation-based life cycle optimization

This article addresses the sustainable design of hydrogen (H₂) production systems that integrate brown and blue pathways with green hydrogen infrastructure. We develop a systematic framework to simultaneously optimize the process superstructure and operating conditions of steam methane reforming (SMR)-based hydrogen production systems. A comprehensive superstructure that integrates SMR with multiple carbon dioxide capture technologies, electrolyzers, fuel cells, and working fluids in the organic rankine cycle is proposed under varying operating conditions. A life cycle optimization model is then developed by integrating superstructure optimization, life cycle assessment approach, techno-economic assessment, and process optimization using extensive process simulation models and formulated as a mixed-integer nonlinear program. We find that the optimal unit-levelized cost of hydrogen ranges from $1.49 to $3.18 per kg H₂. Moreover, the most environmentally friendly process attains net-zero life cycle greenhouse gas emissions compared to 10.55 kg CO₂-eq per kg H₂ for the most economically competitive process design.     

Sustainable ammonia production through process synthesis and global optimization

Current ammonia production technologies have a significant carbon footprint. In this study, we present a process synthesis and global optimization framework to discover the efficient utilization of renewable resources in ammonia production. Competing technologies are incorporated in a process superstructure where biomass, wind, and solar routes are compared with the natural gas-based reference case. A deterministic global optimization-based branch-and-bound algorithm is used to solve the resulting large-scale nonconvex mixed-integer nonlinear programming problem (MINLP). Case studies for Texas, California, and Iowa are conducted to examine the effects of different feedstock prices and availabilities. Results indicate that profitability of ammonia production is highly sensitive to feedstock and electricity prices, as well as greenhouse gas (GHG) restrictions. Under strict 75% GHG reductions, biomass to ammonia route is found to be competitive with natural gas route, whereas wind and solar to ammonia routes require further improvement to compete with those two routes. © 2018 American Institute of Chemical Engineers AIChE J, 65: e16498 2019     

甲醛生产过程能量综合优化

通过对甲醇氧化、甲醛吸收等工艺改进及过程能量优化,实现甲醛生产装置的高产低耗。介绍了传统银催化法甲醛生产工艺流程和过程用能特点,对甲醛生产各个环节进行了用能分析,找出过程用能的薄弱环节,从全局角度进行综合优化,提出甲醛生产工艺优化流程和相应的用能优化措施。     

Sustainable design of geothermal energy systems for electric power generation using life cycle optimization

This article addresses the sustainable design of organic Rankine cycle-based geothermal binary power systems under economic and environmental criteria. A novel superstructure with multiple heat source temperatures, working fluids, and heat rejection systems is proposed. Based on the superstructure, a life cycle optimization model is formulated as a mixed-integer nonlinear fractional program (MINFP) to determine the optimal design. The nonconvex MINFP is efficiently solved by a tailored global optimization algorithm. Two case studies are considered to demonstrate the proposed modeling framework and solution algorithm. One case is based on a geothermal energy system located in California, and the other one is in New York (NY) State. The results show that the geothermal energy system in California is much more economically competitive than that in NY State. The difference in life cycle environmental impacts is less pronounced because the environmental impacts are less sensitive to geological conditions than the capital investments.     

甲醇合成及精馏单元的能效优化

甲醇生产工艺普遍存在能耗、水耗过高的问题,对该工艺进行过程集成节能研究,具有重要的意义。以60万t/a煤制甲醇装置为背景,将处于上下游关系的甲醇合成及精馏单元作为一个系统考虑。利用夹点技术对该系统的用能现状和换热网络进行了分析,找出了违背夹点设计原则的不合理换热匹配。在此基础上,通过充分回收系统高温热源尤其是甲醇合成塔出塔合成气的能量,提出了2种现行换热网络的优化方案。方案1:节约低压蒸汽34.8%,节约脱盐水和循环冷却水21.1%,其中节约1.2 MPa低压蒸汽2 277.7 kW,节约0.3 MPa低压蒸汽20 544.4 kW;方案2:节约低压蒸汽30.8%,节约脱盐水和循环冷却水18.7%,其中节约1.2 MPa低压蒸汽6 027.0 kW,节约0.3 MPa低压蒸汽14 157.5 kW。当1.2 MPa与0.3 MPa低压蒸汽价格差距较大时,选择方案2较合理。     

A novel hybrid feedstock to liquids and electricity process: Process modeling and exergoeconomic life cycle optimization

This article proposes a novel hybrid low‐rank coal (LRC)/biomass/natural gas process for producing liquid fuels and electricity. The hybrid process highlights coexistence of indirect and direct liquefaction technologies, cogasification of char and biomass, and corefinery of LRC syncrude and Fischer–Tropsch syncrude. A process simulation based on detailed chemical kinetics is present to illustrate its feasibility. In addition, we propose an exergoeconomic life cycle optimization framework that seeks to maximize the primary exergy saving ratio, primary total overnight cost saving ratio, life cycle waste emissions avoidance ratio, and primary levelized cost saving ratio by comparing the proposed hybrid process to its reference stand‐alone subsystems. From the results, we can determine four optimal designs which yield competitive breakeven oil prices ranging from $1.87/GGE to $2.13/GGE. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3739–3753, 2014     

Energy in chemical manufacturing processes: gate‐to‐gate information for life cycle assessment

Gate‐to‐gate process energy for 86 chemical manufacturing processes is presented. The estimation of the process energy follows design‐based methodology. Results show that the gate‐to‐gate process energy for half of organic chemicals ranges from 0 to 4 MJ per kg, and for half of inorganic chemicals ranges from ?1 to 3 MJ per kg. The main energy source in both organic and inorganic processes is steam energy followed by potential recovered energy. In organic chemicals, the fractions of heating oil and electricity use are relatively low, but these fractions are higher in the inorganic chemicals than in the organic chemicals. Furthermore, about 50% of the energy consumed in chemical processes is used for purifying the product, byproduct or recycled stream, which indicates that there are large opportunities for improving the process energy in chemical processes. The information presented in this study is very important for those in the life cycle assessment community in order for them to identify inaccurate information or information not based on actual process design. However, the range for the entire range of chemicals is very substantial and thus reflects the need of the life cycle inventory to separately evaluate the chemistry and degree of purity for chemical products. Copyright © 2003 Society of Chemical Industry     

有旁路换热网络全周期节能的动态优化控制实现方法

为了实现换热网络的全周期持续节能,在网络上设置旁路从而增加其控制自由度,同时设计一定的裕量来提供优化控制的操作空间。为了较好地利用旁路调节和裕量空间,提出一种基于换热网络动态模型的在线优化控制方法,巧妙地结合原有常规控制回路,不但扩大了优化控制的可行域,并且满足原常规控制回路的精度要求。该方法以换热网络一定周期内的累积费用最小为目标函数,同时考虑扰动对换热网络的影响,在满足工艺条件的基础上,求解最佳旁路开度,以实现换热网络的持续节能。由于采用闭环校正、迭代计算和滚动优化的实施方法,始终把优化建立在实际的基础上,尽管它每次不一定能得到全局最优解,然而使得实际控制结果达到最优。最后,以某炼油厂的常减压脱盐前换热网络为具体的研究对象,说明所提方法的有效性和使用前景。     

Computer-aided process engineering for environmental efficiency: Industrial drying of biomass

The idea of taking into account environmental impact criteria in the process design becomes a necessity for both the industry and governments, due to increased binding regulations. Moreover, to address the issue of integrating sustainable processes, environmental impact must be weighed and balanced against other concerns, such as economic performance, product quality, and long-term sustainability. Therefore, this study introduces a methodology for environmental impact minimization and optimization of multiple conflicting criteria. A general eco-design method for biomass drying process is proposed. The main target is to develop an assessment computer-aided process engineering tool that compares environmental impacts of different operating conditions and fuel types to support decision-makers for an improved compliance to environmental criterion and sustainability.     

Study of Total Process Energy Integration

1 INTRODUCTIONIt is known that a process system,typically a chemical process system,is composed of subsystemsof reaction,separation,heat recovery and utility with strong interactions among them.In thepast,in order to reduce the complexity of the problem,the decomposition strategy was oftenused in process energy analysis and optimization design.According to the decomposition strategy,analysis and optimization of a system are performed heuristically in several steps which correspond     

A new superstructure optimization paradigm for process synthesis with product distribution optimization: Application to an integrated shale gas processing and chemical manufacturing process

We propose a novel process synthesis framework that combines product distribution optimization of chemical reactions and superstructure optimization of the process flowsheet. A superstructure with a set of technology/process alternatives is first developed. Next, the product distributions of the involved chemical reactions are optimized to maximize the profits of the effluent products. Extensive process simulations are then performed to collect high‐fidelity process data tailored to the optimal product distributions. Based on the simulation results, a superstructure optimization model is formulated as a mixed‐integer nonlinear program (MINLP) to determine the optimal process design. A tailored global optimization algorithm is used to efficiently solve the large‐scale nonconvex MINLP problem. The resulting optimal process design is further validated by a whole‐process simulation. The proposed framework is applied to a comprehensive superstructure of an integrated shale gas processing and chemical manufacturing process, which involves steam cracking of ethane, propane, n‐butane, and i‐butane. © 2017 American Institute of Chemical Engineers AIChE J, 63: 123–143, 2018     

橡胶行业的发展商机

阐述了橡胶工业的发展特点与商机,研究了车市回暖刺激车用橡胶产品市场的态势,以及车用轮胎产品拉动橡胶市场的需求;指出了橡胶工业的高新技术产品开辟了新经济的增长点,橡胶工业的发展趋势及市场前景。     

橡胶行业的发展商机

阐述了橡胶工业的发展特点与商机,研究了车市回暖刺激车用橡胶产品市场的态势,以及车用轮胎产品拉动橡胶市场的需求：指出了橡胶工业的高新技术产品开辟了新经济的增长点,橡胶工业的发展趋势及市场前景。     

生命周期成本分析及其应用研究

采用生命周期思想,通过对产品生命周期内的环境影响货币化和产品生产过程中内部成本的核算,建立综合考虑环境性能和经济性能的产品生命周期成本模型。在成本模型分析的基础上,提出产品绿色因子和绿色比值两个指标,为不同工艺或产品的性能比较提供量化依据。以天然气生产乙炔为案例分析对象,结果表明成本模型能够有效地识别影响产品综合性能的关键因素和最优的产品工艺方案的选择。     

Dynamic real‐time optimization and control of a hybrid energy system

A proactive energy management strategy for a stand‐alone hybrid renewable energy system is presented. The study was motivated by the system built in Lambton College (Sarnia, Ontario, Canada) which includes photovoltaic arrays, wind turbine, battery, electrolyzers, hydrogen storage tanks, and fuel cells. The control architecture consists of two levels of hierarchy: (1) optimal predictive scheduling at the supervisory level and (2) local controllers for each of the system units. A “day‐ahead” approach is followed at the supervisory level and a bidirectional communication between the supervisory, proactive control, and the low‐level control layer is established. The proposed energy management strategy accounts for external (i.e., weather and demand) and internal disturbances. The efficacy of the proposed strategy is demonstrated through case studies. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2546–2556, 2014     

Process synthesis using block superstructure with automated flowsheet generation and optimization

An alternative method for chemical process synthesis using a block‐based superstructure representation is proposed. The block‐based superstructure is a collection of blocks arranged in a two‐dimensional grid. The assignment of different equipment on blocks and the determination of their connectivity are performed using a mixed‐integer nonlinear formulation for automated flowsheet generation and optimization‐based process synthesis. Based on the special structure of the block representation, an efficient strategy is proposed to generate and successively refine feasible and optimized process flowsheets. Our approach is demonstrated using two process synthesis case studies adapted from the literature and one new process synthesis problem for methanol production from biogas © 2018 American Institute of Chemical Engineers AIChE J, 64: 3082–3100, 2018     

Global optimization for sustainable design and synthesis of algae processing network for CO2 mitigation and biofuel production using life cycle optimization

Global optimization for sustainable design and synthesis of a large‐scale algae processing network under economic and environmental criteria is addressed. An algae processing network superstructure including 7800 processing routes is proposed. Based on the superstructure, a multiobjective mixed‐integer nonlinear programming (MINLP) model is developed to simultaneously optimize the unit cost and the unit global warming potential (GWP). To efficiently solve the nonconvex MINLP model with separable concave terms and mixed‐integer fractional terms in the objective functions, a global optimization strategy that integrates a branch‐and‐refine algorithm based on successive piecewise linear approximations is proposed and an exact parametric algorithm based on Newton's method. Two Pareto‐optimal curves are obtained for biofuel production and biological carbon sequestration, respectively. The unit annual biofuel production cost ranges from $7.02/gasoline gallon equivalent (GGE) to $9.71/GGE, corresponding to unit GWP's of 26.491 to 16.52 kg CO₂‐eq/GGE, respectively. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3195–3210, 2014     

过程系统的能量综合和优化

本文论述了从能量变化的角度分析过程系统以及按照Ｙｏｎｇ经济学关系建立系统优化的目标函数和约束条件的必要性，概述了按照过程系统能量结构特点所建立的三环节Ｙｏｎｇ经济分析模型，及其在四类子系统－单元过程设备两级能量综合优化中的应用。然后讨论了全局综合优化问题，介绍了以Ｙｏｎｇ经济学为基础提出的３个全局综合优化策略：子系统分解协调优化、复合措施和全局改进方案的Ｙｏｎｇ经济评价调优，及这一系统方法的研究、