Pyrolysis pretreatment of biomass for entrained-flow gasification

The biomass for entrained-flow gasification needs to be pretreated to significantly increase its heating value and to make it more readily transportable. The pyrolysis pretreatment was conducted in a lab scale fixed-bed reactor; the reactor was heated to elevate the temperature at 5 °C/min before holding at the desired pyrolysis temperature for 1.5 h a fixed time. The effects of pyrolysis temperature on the yield, composition and heating value of the gaseous, liquid and solid products were determined. The pyrolysis removed most oxygenated constituents of rice straw while significantly increased its energy density. Meantime, it changes the physical properties of biomass powders. The results show that the angle of repose, the angle of internal friction of semi-char decrease obviously; the bulk density of semi-char is bigger than that of biomass. This could favor the feeding of biomass. Considering yield and heating value of the solid semi-char product and the feeding problem, the best pyrolysis temperature was 400 °C. The results of this study have confirmed the feasibility of employing pyrolyzed biomass for entrained-flow gasification; they are useful for the additional studies that will be necessary for designing an efficient biomass entrained-flow gasification system.     

生物质的热裂解与热解油的精制

生物质能属于可再生能源，其利用符合社会可持续发展的原则。生物质在中等温度下(约500℃)热裂解主要得到热解油。介绍了温度对热裂解过程的影响、热解油——水的二元相图、热裂解过程的机理和热解油的特性，综述了催化剂种类，溶剂等对热解油催化裂解的影响。结果表明，催化剂H-ZSM-5的脱氧效果最好，以四氢萘为溶剂时，精制油的收率大幅提高，达39．4％。     

生物质及其热裂解产物生物油的特性分析

以红松、白松、落叶松、玉米秸秆等不同生物质为原料,对流化床反应器热裂解制取的生物油进行了研究试验,通过对生物油的物理特性及其成分的分析,得出的实验结果表明:红松制取的生物油品质最好,热值高,含水率低,更适合进一步改性研究和应用,并利用现代精密仪器GC-MS对生物油进行了组分分析,解释了生物油高含氧和高含水特性。     

Pyrolysis characteristics of RDF and HPDE blends with biomass

The main objective of this work was to study refuse-derived fuels (RDF) and high-density polyethylene (HDPE) upgrading by pyrolysis of blends of these materials with wood. The study considered three operational conditions: cracking temperature, heating rate, and different wt.% of RDF and HDPE. The results demonstrate that the cracking temperature of 500 °C and the faster heating rates increased the liquid yield for RDF blends. On the other hand, HDPE blends favor gas production at 550 °C and faster heating rates, which enhance the process operativity because polymeric materials generate waxes and are reduced beneath such conditions. Finally, produced gas LHV increases as RDF and HDPE were added. For example, the LHV of the produced gas only with wood at 550 °C and 20 °C/min was 10.34 MJ/m³ and with 25 wt% HDPE was 14.82 MJ/m³.     

Enhanced electricity generation using biomass materials

Renewable energy is a promising alternative solution for the energy requirements because it is clean and environmentally safe. Projections are important tools for long-term planning and policy settings. According to estimates, by 2040 approximately half of the global energy supply would be from renewable sources. Biomass can be converted into electric power through several methods. Heat is used to thermochemically convert biomass into a fuel oil which is then burned like petroleum to generate electricity. Biomass can also be burned directly to produce steam for electricity production or manufacturing processes. One alternative for producing electricity from biomass in a gas turbine is direct combustion of biomass as a primary energy source. Biomass is burned directly to produce steam, the steam turns a turbine which derives a generator thus electricity is generated.     

Planting rates and delays during the establishment of willow biomass crops

Biomass for bioproducts and bioenergy can be sourced from multiple sources. There is little information on commercial planting operations for willow biomass crops in North America. The objectives of this study were to evaluate the field capacities of two commercial machines (Step and Egedal Energy Planter) planting willow crops in northern New York State, determine the amount and distribution of delays. A study was conducted to evaluate planter activities. The two machines had similar mean field capacities (C_f) ranging from 0.89 to 1.14 ha h⁻¹. Above-average rainfall in the later part of the planting season decreased C_f by over 20% for the Step planter from 1.14 to 0.91 ha h⁻¹; largely due to delays in the headlands. Approximately 70% of the total delay time associated with the Step planter consisted of long-duration delays (>5 min) compared to 35% for the Egedal. Quality of planting stock was an issue for operations; undersized stems resulted in feeding issues. Several potential factors were identified for improved planting operations: loading stems and clearing feeding mechanisms at each turn, improved planting stock and quality control, improving machine design for wet conditions, and improved preparation for in-field repairs. In-field delays should be minimized to reduce demand on the crew and ensure a more uniform crop is established in the field.     

Efficient valorization of biomass to biofuels with bifunctional solid catalytic materials

Mono-functional catalytic materials are used for many types of chemical transformations, but are tedious for delivering products from multiple-step reactions required for the valorization of biomass. An emerging trend is to integrate catalytic transformations, reaction engineering and product separation into a single operation, wherein catalyst design is considered as the key approach to develop efficient, low energy and environmentally-friendly reaction systems. Bifunctional solid catalysts open a door for carrying out domino/cascade- and tandem/sequential-type reactions in a single pot, for which the number of isolation or purification steps can be lessened or eliminated so that removal of unwanted by-products becomes unnecessary. This review introduces bifunctional materials used in one-pot multiple transformations of biomass into biofuels and related chemicals. Emphasis is placed on the assessment of the bifunctionality of catalytic materials, including Bronsted–Lewis acid, acid–base, and metal particles–acid or base bifunctional catalysts with some discussion being on combined catalytic systems with electrochemical, chemo-enzymatic and photochemical methods. Plausible reaction mechanisms for key pathways are shown. Relevant auxiliaries to boost catalytic activity and product selectivity, such as reaction media, heating modes and morphological properties of the catalytic materials are analyzed. Use of appropriate bifunctional catalytic materials provides many opportunities for design of highly efficient reaction systems and simplified processing for producing biofuels and chemicals from lignocellulosic biomass.     

Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 1: Pyrolysis systems

Since the energy crises of the 1970s, many countries have become interest in biomass as a fuel source to expand the development of domestic and renewable energy sources and reduce the environmental impacts of energy production. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles and providing process heat for industrial facilities. The methods available for energy production from biomass can be divided into two main categories: thermo-chemical and biological conversion routes. There are several thermo-chemical routes for biomass-based energy production, such as direct combustion, liquefaction, pyrolysis, supercritical water extraction, gasification, air–steam gasification and so on. The pyrolysis is thermal degradation of biomass by heat in the absence of oxygen, which results in the production of charcoal (solid), bio-oil (liquid), and fuel gas products. Pyrolysis liquid is referred to in the literature by terms such as pyrolysis oil, bio-oil, bio-crude oil, bio-fuel oil, wood liquid, wood oil, liquid smoke, wood distillates, pyroligneous tar, and pyroligneous acid. Bio-oil can be used as a fuel in boilers, diesel engines or gas turbines for heat and electricity generation.     

Pyrolysis studies of polymeric materials used as binders in composite propellants: A review

A review is presented of pyrolysis studies of polymeric materials (with the emphasis on polybutadiene-type polymers) which are used as binders in composite propellants. Where possible, the polymer pyrolysis characteristics are discussed in terms of their relevance to combustion studies of propellants containing these (or similar) polymers as binders. It is shown that binders should receive more attention in any study on composite propellant combustion-both physical and chemical properties may be important, although there is no way as yet to decide beforehand which one plays the larger role. Classical thermoanalytical techniques using bulk heating and low heat rates (fluxes) to study pyrolysis are shown to produce kinetic data which are dependent on heat rate and sample mass, and which are of doubtful relevance to studies of rocket propellant combustion where pyrolysis is linear and heat fluxes are very large.     

Pyrolysis of biomass in a semi-industrial scale reactor: Study of the fuel-nitrogen oxidation during combustion of volatiles

In this work, an experimental study of the NOx-fuel formation, carried out on a semi-industrial scale reactor during combustion of volatiles of the pyrolysis, is performed. Two different biomasses with different nitrogen contents such as a mixture of organic sludge and wood were tested. Results show that the temperature of pyrolysis does not obviously affect the production of NOx-fuel because of the most active precursors (NH₃ and HCN) are already released at low temperatures (400 °C). In the case of sludge mixture, the combustion conditions play the discriminating role in the production of NOx-fuel: the higher the excess air ratio the larger the production of nitrogen oxides from N-fuel.     

The influence of organic and inorganic fertiliser application rates on UK biomass crop sustainability

Bioenergy and energy crops are an important part of the UK’s renewable energy strategy to reach its greenhouse gas reduction target of 80% by 2050. Ensuring the sustainability of biomass feedstocks requires a greater understanding of all aspects of energy crop production, their ecological impacts and yields. This work compares the life-cycle environmental impact of natural gas and biomass from two energy crop systems grown under typical UK agronomic practice. As reported in previous studies the energy crops provide significant reductions in global warming potential (GWP) compared to natural gas. Compared to no fertiliser application, applying inorganic fertiliser increases the GWP by 2% and applying sewage sludge increases the GWP by a lesser extent. In terms of an equivalent GWP savings per unit area of land, the emissions associated with fertiliser production and application can be offset by a yield increase of <0.2 t/ha. However, very large increases in eutrophication and acidification levels are incurred compared to the natural gas reference case when applying either fertiliser. For sewage sludge the impact of varying the allocation factor between the function of wastewater treatment and that of crop growth is also illustrated.     

Characterization of biochar and bio-oil samples obtained from carbonization of various biomass materials

Apricot stone, hazelnut shell, grapeseed and chestnut shell are important biomass residues obtained from the food processing industry in Turkey and they have a great importance as being a source of energy. In this study, the characteristics of bio-oil and biochar samples obtained from the carbonization of apricot stone, hazelnut shell, grapeseed and chestnut shell were investigated. It was found that the biochar products can be characterized as carbon rich, high heating value and relatively pollution-free potential solid biofuels. The bio-oil products were also presented as environmentally friendly green biofuel candidates.     

玉米秸秆热解特性及其动力学研究

用热重分析方法研究了玉米全秸秆、秸皮和玉米叶的热解失重过程和热解特性.结果表明:3种原料的热解过程相似,分为预热解、主热解和碳化3个阶段,且均在340C左右达到最大失重速率;玉米全秸秆的热解特征指数最大,挥发分析出特性最好,其次是秸皮和玉米叶;采用不同反应级数n进行动力学拟合发现:n=2时的热解动力学拟合效果较n=1好,同时玉米全秸秆的动力学参数均最大,玉米叶最小,即全秸秆需要最多的热量才可以热解,但开始热解后其热解过程也相对更容易进行.     

Pyrolysis as a technique for separating heavy metals from hyperaccumulators. Part II: Lab-scale pyrolysis of synthetic hyperaccumulator biomass

Synthetic hyperaccumulator biomass (SHB) impregnated with Ni, Zn, Cu, Co or Cr was used to conduct 11 experiments in a lab-scale fluidized bed reactor. Two runs with blank corn stover, with no metal added, were also conducted. The reactor was operated in an entrained mode in a oxygen-free (N₂) environment at 873 K and 1 atm. The apparent gas residence time through the lab-scale reactor was 0.6 s at 873 K.

The material balance for the lab-scale experiments on N₂-free basis varied between 81% and 98%. The presence of a heavy metal in the SHB decreased the char yield and increased the tar yield, compared to the blank. The char and gas yields appeared to depend on the form of the metal salt used to prepare the SHB. However, the metal distribution in the product streams did not seem to be influenced by the chemical form of the metal salt used to prepare the SHB. Greater than 98.5% of the metal in the product stream was concentrated in the char formed by pyrolyzing and gasifying the SHB in the reactor. The metal concentration in the char varied between 0.7 and 15.3% depending on the type of metal in the SHB. However, the metal concentration was increased 4 to 6 times in the char compared to the feed.     

超细褐煤粉的热解特性及其热解机理

在利用热重法判断热解反应机理时,传统方法很难确切推断反应的机理。为此,从热解曲线和动力学方程出发,运用双外推法,得到了平均颗粒粒度为10．68μm元宝山褐煤热解低温段部分的机理为Anti-Jander三维扩散方程;同时对元宝山褐煤不同粒度煤样的热解特性进行了研究,析了升温速率和颗粒粒度对煤粉热解特性的影响。     

Evaluation of various carbon materials supported Pt catalyts for aqueous-phase reforming of lignocellulosic biomass hydrolysate

Currently, under huge pressure from energy demands and environmental problems, much attention is being paid to produce fuel and chemicals from lignocellulosic biomass. In this matter, development of active and also recyclable catalysts are essential. In the present study, various types of carbon supported Pt reforming catalysts were prepared for use in gasification of wheat straw biomass hydrolysate by aqueous-phase reforming. The supports tested were various carbon materials having different surface and structures that were activated carbon (AC), single- and multi-walled carbon nanotubes (SWCNT and MWCNT), superdarco carbon (SDC) and graphene oxide (GO). The catalysts prepared using these supports were evaluated based on gasification yield, carbon amount consumed in the process, sugar alcohols formation and breaking down of organic compounds in the hydrolysate.     

我国南方地区几种常见生物质材料的热值测定

文中对我国生物质资源的潜力进行分析,得出我国拥有较为丰富的生物质资源;采用氧弹法对南方地区常见生物质秸秆材料的热值进行实验。从实验结果中分别和标煤做对比,得出相应的折标煤系数,结果表明生物质材料作为我国可再生能源具有很大的发展潜力。     

Recent development of transition metal doped carbon materials derived from biomass for hydrogen evolution reaction

Achieving high catalytic performance with the lowest cost is critical for hydrogen evolution reduction. In recent years, biomass-derived carbon catalysts have triggered huge interest in catalytic reactions owing to the low cost, high energy conversion efficiency and environmental friendliness. A rapid growth of novel electrocatalysts is witnessed especially those based on non-precious metals, some of which approach the activity of precious metals. Synergistic interactions between metals and heteroatoms can significantly improve the electrocatalytic activity, thus transition metal-decorated biomass-based carbon materials were commonly adopted to improve HER performance. The resulting electrocatalytic activities are introduced and compared to conventional Pt/C-based electrocatalysts in present research. Moreover, the remaining challenges in the development process and future prospects of hydrogen evolution reduction catalysts are discussed.