Process synthesis of hybrid coal,biomass, and natural gas to liquids via Fischer–Tropsch synthesis,ZSM-5 catalytic conversion,methanol synthesis,methanol-to-gasoline,and methanol-to-olefins/distillate technologies

Several technologies for synthesis gas (syngas) refining are introduced into a thermochemical based superstructure that will convert biomass, coal, and natural gas to liquid transportation fuels using Fischer–Tropsch (FT) synthesis or methanol synthesis. The FT effluent can be (i) refined into gasoline, diesel, and kerosene or (ii) catalytically converted to gasoline and distillate over a ZSM-5 zeolite. Methanol can be converted using ZSM-5 (i) directly to gasoline or to (ii) distillate via olefin intermediates. A mixed-integer nonlinear optimization model that includes simultaneous heat, power, and water integration is solved to global optimality to determine the process topologies that will produce the liquid fuels at the lowest cost. Twenty-four case studies consisting of different (a) liquid fuel combinations, (b) refinery capacities, and (c) superstructure possibilities are analyzed to identify important process topological differences and their effect on the overall system cost, the process material/energy balances, and the well-to-wheel greenhouse gas emissions.     

Overview and some issues related to co‐firing biomass and coal

Low heating values, variable chemical compositions, peculiar physical properties, high investment cost and insecurity of biomass feedstocks supply limit the applications of biomass for energy and other processes. Co‐firing biomass and coal has potential for the development of biomass‐to‐energy capacity with significant economic, environmental, and social benefits. However, co‐firing is not straightforward, and some questions need to be addressed due to the differences in chemical compositions and physical properties of biomass and coal. This paper highlights key issues related to co‐firing, including reactor types, feeding, hydrodynamics, ash sintering, fouling, and corrosion, based on previous studies, as well as calculations and analysis. Direct co‐firing is the most common option for biomass and coal co‐firing currently, mostly due to relatively low investment needed to turn existing coal power plants into co‐firing plants. For direct co‐firing, the physical characteristics and chemical compositions of the fuel entering the combustors or gasifiers are critical to an optimum operation. Any biomass mixed with coal needs to have acceptable physical properties. More research is needed on co‐firing biomass and coal, including work on: preparation, handling, storage, and feeding of biomass feedstocks (e.g. drying, torrefaction, pelletization); co‐firing mechanisms; hydrodynamic analysis of co‐firing combustors and gasifiers; boiler/gasifier capacity, slagging, fouling, corrosion, efficiency, reliability, fuel flexibility; lower emissions and gas cleaning; catalyst poisoning; investment and operating costs.     

生物质热裂解实验和模型研究(英文)

The analysis on the feedstock pyrolysis characteristic and the impacts of process parameters on pyrolysis outcomes can assist in the designing,operating and optimizing pyrolysis processes.This work aims to utilize both experimental and modelling approaches to perform the analysis on three biomass feedstocks—wood sawdust,bamboo shred and Jatropha Curcas seed cake residue,and to provide insights for the design and operation of pyrolysis processes.For the experimental part,the study investigated the effect of heating rate,final pyrolysis temperature and sample size on pyrolysis using common thermal analysis techniques.For the modelling part,a transient mathematical model that integrates the feedstock characteristic from the experimental study was used to simulate the pyrolysis progress of selected biomass feedstock particles for reactor scenarios.The model composes of several sub-models that describe pyrolysis kinetic and heat flow,particle heat transfer,particle shrinking and reactor operation.With better understanding of the effects of process conditions and feedstock characteristics on pyrolysis through both experimental and modelling studies,this work discusses on the considerations of and interrelation between feedstock size,pyrolysis energy usage,processing time and product quality for the design and operation of pyrolysis processes.     

Experimental investigation of a packed-bed solar reactor for the steam-gasification of carbonaceous feedstocks

Steam-gasification of coal, biomass, and carbonaceous waste feedstocks for syngas production is performed using concentrated solar energy as the source of high-temperature process heat. The solar reactor consists of two cavities separated by a SiC-coated graphite plate, with the upper one serving as the radiative absorber and the lower one containing the reacting packed bed that shrinks as the reaction progresses. The carbonaceous feedstocks tested were industrial and sewage sludges, scrap tire powder, fluff, South African coal, and beech charcoal, and are characterized by having a wide range of volatile, ash, and fixed carbon contents, elemental compositions, and physical properties. A 5 kW solar reactor prototype, subjected to radiative flux concentrations up to 2953 suns and operated at temperatures up to 1490 K, yielded high-quality syngas of typical molar ratios H₂/CO = 1.5 and CO₂/CO = 0.2, and with a calorific content up to 30% upgraded over that of the input feedstock. Solar-to-chemical energy conversion efficiencies varied between 17.3% and 29%. Pyrolysis was evident through the evolution of higher gaseous hydrocarbons and liquid tars during heating of the packed bed. The engineering design, fabrication, and testing of the solar reactor are described.     

A comparison of circulating fluidised bed combustion and gasification power plant technologies for processing mixtures of coal,biomass and plastic waste

Environmental regulations concerning emission limitations from the use of fossil fuels in large combustion plants have stimulated interest in biomass for electricity generation.The main objective of the present study was to examine the technical and economic viability of using combustion and gasification of coal mixed with biomass and plastic wastes, with the aim of developing an environmentally acceptable process to decrease their amounts in the waste stream through energy recovery. Mixtures of a high ash coal with biomass and/or plastic using fluidised bed technologies (combustion and gasification) were considered. Experiments were carried out in laboratory and pilot plant fluidised bed systems on the combustion and air/catalyst and air/steam gasification of these feedstocks and the data obtained were used in the techno-economic analyses.The experimental results were used in simulations of medium to large-scale circulating fluidised bed (CFB) power generation plants. Techno-economic analysis of the modelled CFB combustion systems showed efficiencies of around 40.5% (and around 46.5% for the modelled CFB gasification systems) when fuelled solely by coal, which were only minimally affected by co-firing with up to 20% biomass and/or wastes. Specific investments were found to be around $2150/kWe to $2400/kWe ($1350/kWe to $1450/kWe) and break-even electricity selling prices to be around $68/MWh to $78/MWh ($49/MWh to $54/MWh). Their emissions were found to be within the emission limit values of the large combustion plant directive.Fluidised bed technologies were found to be very suitable for co-firing coal and biomass and/or plastic waste and to offer good options for the replacement of obsolete or polluting power plants.     

Flowsheet Modeling and Simulation of Biomass Steam Gasification for Hydrogen Production

Hydrogen production from biomass steam gasification is systematically reviewed. Equilibrium modeling and simulation studies using various techniques for effective hydrogen production are presented. Heat integration, economic analysis of the hydrogen production, and systematic design algorithms research publications are overviewed and discussed for energy-efficient and economic hydrogen production from various biomass feedstocks. Comparison and analysis of the results strongly suggest the viable potential of biomass steam gasification for hydrogen production from small to large scales with applications for thermal heat, power generation, and many other industrial fields.     

Nationwide energy supply chain analysis for hybrid feedstock processes with significant CO2 emissions reduction

Integrating diverse energy sources to produce cost‐competitive fuels requires efficient resource management. An optimization framework is proposed for a nationwide energy supply chain network using hybrid coal, biomass, and natural gas to liquids (CBGTL) facilities, which are individually optimized with simultaneous heat, power, and water integration using 162 distinct combinations of feedstock types, capacities, and carbon conversion levels. The model integrates the upstream and downstream operations of the facilities, incorporating the delivery of feedstocks, fuel products, electricity supply, water, and CO₂ sequestration, with their geographical distributions. Quantitative economic trade‐offs are established between supply chain configurations that (a) replace petroleum‐based fuels by 100%, 75%, and 50% and (b) utilize the current energy infrastructures. Results suggest that cost‐competitive fuels for the US transportation sector can be produced using domestically available coal, natural gas, and sustainably harvested biomass via an optimal network of CBGTL plants with significant GHG emissions reduction from petroleum‐based processes. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Simulation, integration, and economic analysis of gas-to-liquid processes

Gas-to-liquid (GTL) involves the chemical conversion of natural gas into synthetic crude that can be upgraded and separated into different useful hydrocarbon fractions including liquid transportation fuels. Such technology can also be used to convert other abundant natural resources such as coal and biomass to fuels and value added chemicals (referred to as coal-to-liquid (CTL) and biomass-to-liquid (BTL)). A leading GTL technology is the Fischer-Tropsch (FT) process. The objective of this work is to provide a techno-economic analysis of the GTL process and to identify optimization and integration opportunities for cost saving and reduction of energy usage while accounting for the environmental impact. First, a base-case flowsheet is synthesized to include the key processing steps of the plant. Then, a computer-aided process simulation is carried out to determine the key mass and energy flows, performance criteria, and equipment specifications. Next, energy and mass integration studies are performed to address the following items: (a) heating and cooling utilities, (b) combined heat and power (process cogeneration), (c) management of process water, (c) optimization of tail gas allocation, and (d) recovery of catalyst-supporting hydrocarbon solvents. Finally, these integration studies are conducted and the results are documented in terms of conserving energy and mass resources as well as providing economic impact. Finally, an economic analysis is undertaken to determine the plant capacity needed to achieve the break-even point and to estimate the return on investment for the base-case study.     

Engineering development of a short residence time,coal hydropyrolysis process

Cities Service Research and Development Company (CSRD), the research arm of the Cities Service Company, has been developing a process scheme named the CS-SR Process, for the non-catalytic, vapor-phase, hydrogenation of carbonaceous feedstocks. The initial and primary emphasis in our Energy Research Laboratory was to apply this technology to convert coal into pipeline quality gas and attractive byproduct yields of light aromatic (BTX) liquids.A review of the literature early in 1974 led to our conclusion that the most productive area of process development would be that of short residence time hydrogenation. Clean energy from coal, in all forms be it liquid or gaseous hydrocarbons, is vital to the United States energy independence program. The short residence, rapid heatup hydropyrolysis technique optimizes the conversion of aromatic and aliphatic fragments in coal to light aromatic liquids and the gaseous components of substitute natural gas (SNG). In this way, the CS-SR Process mitigates nature rather than antagonizing it. A brief literature review has been presented in our previous paper at the 1976 ACS (San Francisco) meeting.In the summer of 1974, we designed a 1–4 lb/h bench-scale unit capable of operation at temperatures and pressure that are scalable within present-day, commercial technology. A cold-flow model to test coal—hydrogen mixing injectors and to study coal—hydrogen slip velocities was designed and constructed in Autumn, 1974. Construction of the bench-scale unit began in December 1974 and was completed in June, 1975 with the shakedown operations occurring in the Summer of 1975. The first complete material balance run was made in August, 1975. Since that time, over 175 runs have been made with a variety of feedstocks including lignite, bituminous and subbituminous coals, oil shale, tar sands and coal tars.Further development of the CS-SR Process is being undertaken in several programs supported jointly by Cities Service and DOE. Several experimental programs are continuing in the bench-scale unit to explore conditions for maximizing liquids yields and also for maximizing gas (methane, ethane) yields. Process flowsheet studies are also being made. The next step of development of the CS-SR Process would require about a 6-inch diameter, pilot plant reactor capable of processing about 100 TPD coal. This pilot plant would be one scaleup step away from a 12-inch diameter, single tube, commercial-type operation and a direct scale to a 6-inch diameter, multi-tube, commercial type operation. This paper summarizes the analysis of the bench-scale data obtained when processing a North Dakota lignite.     

生物质直接进料的化学链技术进展

化学链技术(chemical-looping technology,CLT)是主要针对化石燃料、生物质等转化过程的清洁高效技术,正在走向商业化。在生物质为原料的CLT中,相较间接进料,直接进料更受关注。本文综述了近年来生物质直接进料的化学链技术研究进展,包括生物质燃烧、气化、制合成气、制氢以及CO_2捕集等。为促进生物质-CLT发展,需克服生物质本身的不利特性,借鉴以煤为原料的CLT开发,并重点研发化学链氧解耦(chemical looping oxygen uncoupling,CLOU)材料。     

Char and Coke Formation as Unwanted Side Reaction of the Hydrothermal Biomass Gasification

The hydrothermal biomass gasification is a promising technology to produce hydrogen and/or methane from wet biomass with a water content of ≥ 80 % (g/g). In the process, the coke formation usually is very low, but already low amounts may cause problems like, e.g., fouling in the heat exchanger. To learn more about the product formation, the results of the hydrothermal treatment (at 400, 500, 600 °C and 1 h) of different biomass feedstocks (artichoke stalk, pinecone, sawdust, and cellulose as model biomass) in a microreactor are compared. The gas composition and the total organic carbon content of the aqueous phase were determined after reaction. The gas formation rises with increasing temperature. The formation of carbon deposits and their characterization has been investigated by scanning electron microscopy (SEM). The variation of the solid morphology during the hydrothermal conversion is discussed based on chemical pathways occurring during hydrothermal biomass degradation.     

Techno-economical assessment of coal and biomass gasification-based hydrogen production supply chain system

Hydrogen is an energy carrier that represents a possible clean fuel of the future. This paper assesses the effect of biomass co-firing on gasification based hydrogen production supply chain, with carbon dioxide capture and storage, from technical, economical and environmental point of view. Several cases consisting of various feedstocks to the gasification reactor are investigated (coal only and coal in mixture with sawdust or wheat straw). Considered plant concepts generate between 330 and 460 MW hydrogen of 99.99% (vol.) purity.     

煤/煤焦油/沥青质的热等离子体裂解特性比较分析

针对化石资源劣质化和大宗低价值化工中间产品的反应工程新问题,提出利用热等离子体超高温特性实现极端条件下难利用原料的高效清洁转化,重点探讨并比较了煤化工中的原煤、煤焦油和石油化工中的沥青质的热等离子体裂解特性。通过热等离子体裂解实验室小试装置考察了3种典型原料的裂解行为,结果表明,煤焦油和沥青质具有高于煤的转化率和乙炔收率;建立了基于热力学的热等离子体裂解反应过程的能量平衡分析方法,模拟计算了不同操作条件下各原料在兆瓦级中试装置上的裂解结果,给出了相同等离子体能量注入的条件下不同原料裂解过程的物流和能流关系;并进一步模拟分析了原料间混合裂解的混料配比对裂解气的影响,为热等离子体裂解过程的工业原料筛选和原料混合裂解提供了科学依据。     

Design and optimization of biomass power plant

Among the renewable energy sources, biomass offers some benefits due to its low cost and presumed zero-carbon emission when compared with fossil fuels. However, the moisture content of biomass is often high that lowers its heating value, reduces the combustion temperature and causes operational problems. Because of these, when burning biomass for power generation, biomass is often dried prior to the combustion. To lower the drying cost or to maximize the power output of a biomass power plant, proper heat integration in between the steam power plant and the drying process has to be considered. In this work, heat integration studies are performed to a biomass power plant that burns empty fruit bunches (EFB) as fuel. Composite curves of all studied cases are plotted to visualize the intensity and to identify opportunities of heat integration among the drying and power generation systems. A multi-stage drying process is proposed that employs steam and waste-heat from the power plant and the drying process, respectively. Results of this study show that with proper drying and heat integration, the overall efficiency of a biomass power plant can be significantly improved.     

Economics of cellulosic ethanol production in a thermochemical pathway for softwood, hardwood, corn stover and switchgrass

The economics of producing cellulosic ethanol using loblolly pine, natural mixed hardwood, Eucalyptus, corn stover, and switchgrass as feedstocks was simulated in Aspen Plus using the thermochemical process via indirect gasification and mixed alcohol synthesis developed by NREL. Outputs from the simulation were linked to an economic analysis spreadsheet to estimate NPV, IRR, payback and to run further sensitivity analysis of the different combinations of feedstocks. Results indicate that forest-based feedstocks including loblolly pine, natural hardwood and eucalyptus may present more attractive financial returns when compared to switchgrass and corn stover, mainly due to their composition (%C, %H, %ash) and alcohol yield. Simulated alcohol yields from forest-based feedstock were significantly higher than from switchgrass and corn stover. Simulations run with switchgrass and corn stover, also demonstrated greater sensitivity to changes in ethanol price, alcohol yield, capital investment and biomass costs. Furthermore, moisture content of receiving feedstocks greatly affected the economics of the biorefinery. A difference of − 10% in the moisture content of the receiving feedstock affected the NPV of the simulated project by + 25% (with respect to central NPV of ~$192 million).     

Numerical study on effects of coal properties on spontaneous heating in longwall gob areas

A computational fluid dynamics (CFD) study was conducted to model effects of coal properties on the potential for spontaneous heating in longwall gob (mined-out) areas. A two longwall panel district using a bleeder ventilation system was simulated. The permeability and porosity profiles for the longwall gob were generated from a geotechnical model and were used as inputs for the three-dimensional CFD modeling. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous combustion studies. Heat generated from coal oxidation is dissipated by convection and conduction, while oxygen and oxidation products are transported by convection and diffusion. Unsteady state simulations were conducted for three different US coals and simulation results were compared with some available test results. The effects of coal surface area and heat of reaction on the spontaneous heating process were also examined.     

Pyrolysis of coal liquids

The pyrolysis of process recycle solvent derived from Western Kentucky coal via the SRC-II coal liquefaction process was investigated to ascertain the effect of residence time and temperature on the production of olefins. The study was made using an alonized transfer line reactor operating at temperatures of 650 and 730 °C, essentially atmospheric pressure, and residence times up to 0.13 s. A comparison is made with previously published results for the pyrolysis of hydrotreated COED light and heavy coal liquids (subsequently referred to as COED light and heavy oils, respectively) derived from Western Kentucky coal and steam pyrolysis of a hydrogenated fraction of SYNTHOIL derived from Western Kentucky coal. Results indicate that in each case the preferential pyrolysis of the saturate fraction occurs under convential pyrolysis conditions. Ethylene, propylene, and methane were the dominant gas products in all cases. The liquid pyrolysates from the COED oils and SRC-II recycle solvent had lower $\text{H}\text{C}$ ratios and heating values than their respective feedstocks. Mass spectroscopic analysis of the liquid pyrolysates in each case revealed the presence of polycyclic aromatics that were not present in the individual feedstocks. This trend which increased with temperature is indicative of cyclization and/or recombination of free radicals during pyrolysis. It is therefore surmized that the yields of light olefins from primary coal liquefaction products can be improved by partially hydrogenating them prior to pyrolysis. Alternatively, sufficient hydrogen can be provided in the vicinity of cracking to suppress retrogressive reactions which lead to the formation of coke. The pyrolysis of COED oils and SRC-II recycle solvent was found to follow first-order irreversible kinetics. The activation energy for the pyrolysis of the COED light and heavy oil was found to be 76.1 and 70.85 kJ g-mol^?1, respectively.     

煤气化废水处理工艺的现状及发展方向

对煤气化产生废水的特点及其处理难点进行了分析。针对煤气化废水处理的3个主要阶段,分别介绍了近年来一些煤气化废水处理新工艺的应用情况及今后的发展方向,并且提出了企业在选择处理工艺时应注意的问题。     

Catalytic conversion of lignocellulosic biomass to fuels: Process development and technoeconomic evaluation

Levulinic acid (LA) has been identified as a platform chemical, which can be produced from lignocellulosic materials and transformed into liquid fuels, fuel additives and even other specialty chemicals. These conversions have been made possible through recent advances in heterogeneous catalysis. Taking advantage of novel chemistries and catalytic materials, we have developed a LA-based strategy to convert lignocellulosic biomass into liquid hydrocarbon fuels. To assess the economic potential of this approach, a process synthesis effort supported by detailed process simulation and capital/operational cost calculations has been undertaken. Furthermore, we study different feedstocks and perform sensitivity analysis studies for several process and economic parameters. Finally, we present the results of an energy efficiency analysis and discuss biomass transportation aspects.     

Isolation and characterization of humic acids from Alberta oil sands and related materials

Thirteen humic acid samples were isolated from a number of oil sand feedstocks using 0.5 N NaOH or a mixture of 0.1 N NaOH + 0.1 M Na₄P₂O₇. The feedstocks included three different grades of Athabasca oil sand, two samples of overburden, a sample of centrifuge tailings from the Syncrude Canada Ltd plant in Alberta and a heavy minerals fraction from oil sand tailings containing adsorbed organic matter. Based on the extraction efficiency of the two solvents it appears that the humic acids from oil sand and overburden feedstocks are strongly associated with calcium, while the humic acids from other feedstocks could be bound to non-silicate aluminum and/or iron. Comparison of analytical data for the various humic acid samples with corresponding data for humic acids from subbituminous coal, peat, soil and asphaltenes from bituminous feedstock, shows the similarity of these humic acids to those from subbituminous coal. Examination of the elemental analyses in terms of a van Krevelen diagram shows that most of the data either overlap or fall directly in the region of the recent and shallow kerogens. This kind of organic matter has very little potential for oil production, suggesting that the origin of this organic matter could be different from that of the greater part of the bitumen of the Athabasca oil sands.