Using biomass-based fuels including pyrolysis liquids for power and CHP production

The use of biomass-derived liquids (in short: bioliquids) instead of solid biomass can help overcome some of the barriers hindering a wider use of biomass in smaller-scale CHP systems. Relevant bioliquids included biodiesel, vegetable oils as well straight and upgraded pyrolysis oil. In this joint EU-Russian research project Bioliquids-CHP prime movers (engines and turbines) will be developed and modified so that these can run efficiently on bioliquids. At the same time, bioliquids will be upgraded and blended in order to facilitate their use in prime movers. Preliminary results with regard to bioliquid selection, production, and characterisation; the selection and modification of a micro gas turbine; and the development of engines and components are discussed. The research also covers NOx emission reduction and control and an assessment of the benefits and economics of bioliquids-based CHP systems in EU and Russian markets.

Upgrading fast pyrolysis liquids:blends of biodiesel and pyrolysis oil

Fast pyrolysis liquid or bio-oil has been used in engines with limited success. It requires a pilot fuel and/or an additive for successful combustion and there are problems with materials and liquid properties. It is immiscible with all conventional hydrocarbon fuels. Biodiesel, a product of esterification of vegetable oil with an alcohol, is widely used as a renewable liquid fuel as an additive to diesel at up to 20%. There are however limits to its use in conventional engines due to poor low temperature performance and variability in quality from a variety of vegetable oil qualities and variety of esterification processes. Within the European Project Bioliquids-CHP - a joint project between the European Commission and Russia - a study was undertaken to develop small scale CHP units based on engines and microturbines fuelled with bioliquids from fast pyrolysis and methyl esters of vegetable oil. Blends of bio-oil and biodiesel were evaluated and tested to overcome some of the disadvantages of using either fuel by itself. An alcohol was used as the co-solvent in the form of ethanol, 1-butanol or 2-propanol. Visual inspection of the blend homogeneity after 48 h was used as an indicator of the product stability and the results were plotted in a three phase chart for each alcohol used. An accelerated stability test was performed on selected samples in order to predict its long term stability. We concluded that the type and quantity of alcohol is critical for the blend formation and stability. Using 1-butanol gave the widest selection of stable blends, followed by blends with 2-propanol and finally ethanol, thus 1-butanol blends accepted the largest proportion of bio-oil in the mixture. © 2013 Elsevier Ltd. All rights reserved.

Study on the pyrolytic behaviour of xylan-based hemicellulose using TG-FTIR and Py-GC-FTIR

Two sets of experiments, categorized as TG–FTIR and Py–GC–FTIR, are employed to investigate the mechanism of the hemicellulose pyrolysis and the formation of main gaseous and bio-oil products. The “sharp mass loss stage” and the corresponding evolution of the volatile products are examined by the TG–FTIR graphs at the heating rate of 3–80 K/min. A pyrolysis unit, composed of fluidized bed reactor, carbon filter, vapour condensing system and gas storage, is employed to investigate the products of the hemicellulose pyrolysis under different temperatures (400–690 °C) at the feeding flow rate of 600 l/h. The effects of temperature on the condensable products are examined thoroughly. The possible routes for the formation of the products are systematically proposed from the primary decomposition of the three types of unit (xylan, O-acetylxylan and 4-O-methylglucuronic acid) and the secondary reactions of the fragments. It is found that the formation of CO is enhanced with elevated temperature, while slight change is observed for the yield of CO2 which is the predominant products in the gaseous mixture.

Intracellular protein determination using droplet-based immunoassays

This paper describes the implementation of a sensitive, on-chip immunoassay for the analysis of intracellular proteins, developed using microdroplet technology. The system offers a number of analytical functionalities, enabling the lysis of low cell numbers, as well as protein detection and quantification, integrated within a single process flow. Cells were introduced into the device in suspension and were electrically lysed in situ. The cell lysate was subsequently encapsulated together with antibody-functionalized beads into stable, water-in-oil droplets, which were stored on-chip. The binding of intracellular proteins to the beads was monitored fluorescently. By analyzing many individual droplets and quantifying the data obtained against standard additions, we measured the level of two intracellular proteins, namely, HRas-mCitrine, expressed within HEK-293 cells, and actin-EGFP, expressed within MCF-7 cells. We determined the concentrations of these proteins over 5 orders of magnitude, from ~50 pM to 1 µM. The results from this semiautomated method were compared to those for determinations made using Western blots, and were found not only to be faster, but required a smaller number of cells. © 2011 American Chemical Society.

Non-Linear oil firm force coefficients for a journal bearing operating under aligned and misaligned conditions

It is well established that hydrodynamic journal bearings are responsible for self-excited vibrations and have the effect of lowering the critical speeds of rotor systems. The forces within the oil film wedge, generated by the vibrating journal, may be represented by displacement and velocity coefficient~ thus allowing the dynamical behaviour of the rotor to be analysed both for stability purposes and for anticipating the response to unbalance. However, information describing these coefficients is sparse, misleading, and very often not applicable to industrial type bearings. Results of a combined analytical and experimental investigation into the hydrodynamic oil film coefficients operating in the laminar region are therefore presented, the analysis being applied to a 120 degree partial journal bearing having a 5.0 in diameter journal and a LID ratio of 1.0. The theoretical analysis shows that for this type of popular bearing, the eight linearized coefficients do not accurately describe the behaviour of the vibrating journal based on the theory of small perturbations, due to them being masked by the presence of nonlinearity. A method is developed using the second order terms of Taylor expansion whereby design charts are provided which predict the twentyeight force coefficients for both aligned, and for varying amounts of journal misalignment. The resulting non-linear equations of motion are solved using a modified Newton-Raphson method whereby the whirl trajectories are obtained, thus providing a physical appreciation of the bearing characteristics under dynamically loaded conditions.

The influence of the chemical nature of dispersed phase on stability in oil-in-water emulsions

Some of the problems arising from the inherent instability of emulsions are discussed. Aspects of emulsion stability are described and particular attention is given to the influence of the chemical nature of the dispersed phase on adsorbed film structure and stability, Emulsion stability has been measured by a photomicrographic technique. Electrophoresis, interfacial tension and droplet rest-time data were also obtained. Emulsions were prepared using a range of oils, including aliphatic and aromatic hydrocarbons, dispersed In a solution of sodium dodecyl sulphate. In some cases a small amount of alkane or alkanol was incorporated into the oil phase. In general the findings agree with the classical view that the stability of oil-in-water emulsions is favoured by a closely packed interfacial film and appreciable electric charge on the droplets. The inclusion of non-ionic alcohol leads to enhanced stability, presumably owing to the formation of a "mixed" interfacial film which is more closely packed and probably more coherent than that of the anionic surfactant alone. In some instances differences in stability cannot he accounted for simply by differences in interfacial adsorption or droplet charge. Alternative explanations are discussed and it is postulated that the coarsening of emulsions may occur not only hy coalescence but also through the migration of oil from small droplets to larger ones by molecular diffusion. The viability of using the coalescence rates of droplets at a plane interface as a guide to emulsion stability has been researched. The construction of a suitable apparatus and the development of a standard testing procedure are described. Coalescence-time distributions may be correlated by equations similar to those presented by other workers, or by an analysis based upon the log-normal function. Stability parameters for a range of oils are discussed in terms of differences in film drainage and the natl1re of the interfacial film. Despite some broad correlations there is generally poor agreement between droplet and emulsion stabilities. It is concluded that hydrodynamic factors largely determine droplet stability in the systems studied. Consequently droplet rest-time measurements do not provide a sensible indication of emulsion stability,

Estimation of the production cost of fast pyrolysis bio-oil

A number of papers and reports covering the techno-economic analysis of bio-oil production has been published. These have had different scopes, use different feedstocks and reflected national cost structures. This paper reviews and compares their cost estimates and the experimental results that underpin them. A comprehensive cost and performance model was produced based on consensus data from the previous studies or stated scenarios where data is not available that reflected UK costs. The model takes account sales of bio-char that is a co-product of pyrolysis and the electricity consumption of the pyrolysis plant and biomass pre-processing plants. It was concluded that it should be able to produce bio-oil in the UK from energy crops for a similar cost as distillate fuel oil. It was also found that there was little difference in the processing cost for woodchips and baled miscanthus. © 2011 Elsevier Ltd.

Wear of high aluminium zinc-based alloys in plain bearing applications

Two zinc-based alloys of high aluminium content, Super Cosmal alloy containing 60% Al, 6% Si, 1% Cu, 0.3% Mn and HAZCA alloy containing 60% Al, 8% Si, 2% Cu, 0.06% Mg were produced by sand casting. Foundry characteristics in particular, fluidity, mode of solidification and feeding ability were examined. Metallographic analysis of structures was carried out using optical and scanning electron microscopy and their mechanical properties were determined using standard techniques. Dry wear characteristics were determined using a pin-on-disc test, and boundary-lubricated wear was studied using full bearing tests. Results from casting experiments were evaluated and compared with the behaviour of a standard ZA-27 alloy and those from tribological tests with both ZA-27 alloy and a leaded tin-bronze (SAE660) under the same testing conditions. The presence of silicon was beneficial, reducing the temperature range of solidification, improving feeding efficiency and reducing gravity segregation of phases. Use of chills and melt degassing was found necessary to achieve soundness and enhanced mechanical properties. Dry wear tests were performed against a steel counterface for sliding speeds of 0.25, 0.5, 1.0 and 2 m/s and for a range of loads up to 15 kgf. The high aluminium alloys showed wear rates as low as those of ZA-27 at speeds of 0.25 and 0.5 m/s for the whole range of applied loads. ZA-27 performed better at higher speeds. The build up of a surface film on the wearing surface of the test pins was found to be responsible for the mild type of wear of the zinc based alloys. The constitution of the surface film was determined as a complex mixture of aluminium, zinc and iron oxides and metallic elements derived from both sliding materials. For full bearing tests, bushes were machined from sand cast bars and were tested against a steel shaft in the presence of a light spindle oil as the lubricant. Results showed that all zinc based alloys run-in more rapidly than bronze, and that wear in Super Cosmal and HAZCA alloys after prolonged running were similar to those in ZA-27 bearings and significantly smaller than those of the bronze.

The characterisation and optimisation of modified herbaceous grasses for identifying pyrolisis-oil quality traits

The primary objective of this work is to relate the biomass fuel quality to fast pyrolysis-oil quality in order to identify key biomass traits which affect pyrolysis-oil stability. During storage the pyrolysis-oil becomes more viscous due to chemical and physical changes, as reactions and volatile losses occur due to aging. The reason for oil instability begins within the pyrolysis reactor during pyrolysis in which the biomass is rapidly heated in the absence of oxygen, producing free radical volatiles which are then quickly condensed to form the oil. The products formed do not reach thermodynamic equilibrium and in tum the products react with each other to try to achieve product stability. The first aim of this research was to develop and validate a rapid screening method for determining biomass lignin content in comparison to traditional, time consuming and hence costly wet chemical methods such as Klason. Lolium and Festuca grasses were selected to validate the screening method, as these grass genotypes exhibit a low range of Klason /Acid Digestible Fibre lignin contents. The screening methodology was based on the relationship between the lignin derived products from pyrolysis and the lignin content as determined by wet chemistry. The second aim of the research was to determine whether metals have an affect on fast pyrolysis products, and if any clear relationships can be deduced to aid research in feedstock selection for fast pyrolysis processing. It was found that alkali metals, particularly Na and K influence the rate and yield of degradation as well the char content. Pre-washing biomass with water can remove 70% of the total metals, and improve the pyrolysis product characteristics by increasing the organic yield, the temperature in which maximum liquid yield occurs and the proportion of higher molecular weight compounds within the pyrolysis-oil. The third aim identified these feedstock traits and relates them to the pyrolysis-oil quality and stability. It was found that the mineral matter was a key determinant on pyrolysis-oil yield compared to the proportion of lignin. However the higher molecular weight compounds present in the pyrolysis-oil are due to the lignin, and can cause instability within the pyrolysis-oil. The final aim was to investigate if energy crops can be enhanced by agronomical practices to produce a biomass quality which is attractive to the biomass conversion community, as well as giving a good yield to the farmers. It was found that the nitrogen/potassium chloride fertiliser treatments enhances Miscanthus qualities, by producing low ash, high volatiles yields with acceptable yields for farmers. The progress of senescence was measured in terms of biomass characteristics and fast pyrolysis product characteristics. The results obtained from this research are in strong agreement with published literature, and provides new information on quality traits for biomass which affects pyrolysis and pyrolysis-oils.

A techno-economic assessment of the use of fast pyrolysis bio-oil from UK energy crops in the production of electricity and combined heat and power

This thesis investigates the cost of electricity generation using bio-oil produced by the fast pyrolysis of UK energy crops. The study covers cost from the farm to the generator’s terminals. The use of short rotation coppice willow and miscanthus as feedstocks was investigated. All costs and performance data have been taken from published papers, reports or web sites. Generation technologies are compared at scales where they have proved economic burning other fuels, rather than at a given size. A pyrolysis yield model was developed for a bubbling fluidised bed fast pyrolysis reactor from published data to predict bio-oil yields and pyrolysis plant energy demands. Generation using diesel engines, gas turbines in open and combined cycle (CCGT) operation and steam cycle plants was considered. The use of bio-oil storage to allow the pyrolysis and generation plants to operate independently of each other was investigated. The option of using diesel generators and open cycle gas turbines for combined heat and power was examined. The possible cost reductions that could be expected through learning if the technology is widely implemented were considered. It was found that none of the systems analysed would be viable without subsidy, but with the current Renewable Obligation Scheme CCGT plants in the 200 to 350 MWe range, super-critical coal fired boilers co-fired with bio-oil, and groups of diesel engine based CHP schemes supplied by a central pyrolysis plant would be viable. It was found that the cost would reduce with implementation and the planting of more energy crops but some subsidy would still be needed to make the plants viable.

Evaluating and developing project-based learning:an empirical approach to evaluating CDIO

As a global profession, engineering is integral to the maintenance and further development of society. Indeed, contemporary social problems requiring engineering solutions are not only a consequence of natural and ‘manmade’ disasters (such as the Japanese earthquake or the oil leakage in the Gulf of Mexico) but also encapsulate 21st Century dilemmas around sustainability, poverty and pollution [2,6,7]. Given the complexity of such problems and the constant need for innovation, the demand for engineering education to provide a ready supply of suitably qualified engineering graduates, able to make innovative decisions has never been higher [3,5]. Bearing this in mind, and taking account problems of attrition in engineering education [1,6,4] innovation in the way in which the curriculum is developed and delivered is crucial. CDIO [Conceive, Design, Implement, Operate] provides a potentially ground-breaking solution to such dilemmas. Aimed at equipping students with practical engineering skills supported by the necessary theoretical background, CDIO could potentially change the way engineering is perceived and experienced within higher education. Aston University introduced CDIO into its Mechanical Engineering and Design programmes in October 2011. From its induction, engineering education researchers have ‘shadowed’ the staff responsible for developing and teaching the programme. Utilising an Action Research Design, and adopting a mixed methodological research design, the researchers have worked closely with the teaching team to critically reflect on the processes involved in introducing CDIO into the curriculum. Concurrently, research has been conducted to capture students’ perspectives of CDIO. In evaluating the introduction of CDIO at Aston, the researchers have developed a distinctive research strategy with which to evaluate CDIO. It is the emergent findings from this research that form the basis of this paper. Although early-on in its development CDIO is making a significant difference to engineering education at the University. The paper draws attention to pedagogical, practical and professional issues – discussing each one in turn and in doing so critically analysing the value of CDIO from academic, student and industrial perspectives. The paper concludes by noting that whilst CDIO represents a forwardthinking approach to engineering education, the need for constant innovation in learning and teaching should not be forgotten. Indeed, engineering education needs to put itself at the forefront of pedagogic practice. Providing all-rounded engineers, ready to take on the challenges of the 21st Century!

Preparation and characterization of gas-filled liposomes:Can they improve oil recovery?

Although well known for delivering various pharmaceutical agents, liposomes can be prepared to entrap gas rather than aqueous media and have the potential to be used as pressure probes in magnetic resonance imaging (MRI). Using these gas-filled liposomes (GFL) as tracers, MRI imaging of pressure regions of a fluid flowing through a porous medium could be established. This knowledge can be exploited to enhance recovery of oil from the porous rock regions within oil fields. In the preliminary studies, we have optimized the lipid composition of GFL prepared using a simple homogenization technique and investigated key physico-chemical characteristics (size and the physical stability) and their efficacy as pressure probes. In contrast to the liposomes possessing an aqueous core which are prepared at temperatures above their phase transition temperature (Tc), homogenization of the phospholipids such as 1,2-dipalmitoyl-sn-glycero-3- phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocoline (DSPC) in aqueous medium below their Tc was found to be crucial in formation of stable GFL. DSPC based preparations yielded a GFL volume of more than five times compared to their DPPC counter part. Although the initial vesicle sizes of both DSPC and DPPC based GFL were about 10 μm, after 7 days storage at 25°C, the vesicle sizes of both formulations significantly (p < 0.05) increased to 28.3 ± 0.3 μm and 12.3 ± 1.0 μm, respectively. When the DPPC preparation was supplemented with cholesterol at a 1:0.5 or 1:1 molar ratio, significantly (p < 0.05) larger vesicles were formed (12-13 μm), however, compared to DPPC only vesicles, both cholesterol supplemented formulations displayed enhanced stability on storage indicating a stabilizing effect of cholesterol on these gas-filled vesicles. In order to induce surface charge on the GFL, DPPC and cholesterol (1: 0.5 molar ratio) liposomes were supplemented with a cationic surfactant, stearylamine, at a molar ratio of 0.25 or 0.125. Interestingly, the ζ potential values remained around neutrality at both stearylamine ratios suggesting the cationic surfactant was not incorporated within the bilayers of the GFL. Microscopic analysis of GFL confirmed the presence of spherical structures with a size distribution between 1-8 μm. This study has identified that DSPC based GFL in aqueous medium dispersed in 2% w/v methyl cellulose although yielded higher vesicle sizes over time were most stable under high pressures exerted in MRI. Copyright © Informa Healthcare USA, Inc.

Risk-based model aids selection of pipeline inspection, maintenance strategies

The existing method of pipeline monitoring, which requires an entire pipeline to be inspected periodically, wastes time and is expensive. A risk-based model that reduces the amount of time spent on inspection has been developed. This model not only reduces the cost of maintaining petroleum pipelines, but also suggests an efficient design and operation philosophy, construction method and logical insurance plans.The risk-based model uses analytic hierarchy process, a multiple attribute decision-making technique, to identify factors that influence failure on specific segments and analyze their effects by determining the probabilities of risk factors. The severity of failure is determined through consequence analysis, which establishes the effect of a failure in terms of cost caused by each risk factor and determines the cumulative effect of failure through probability analysis.

The development of a wax layer on the interior wall of a circular pipe transporting heated oil

In this article we develop a simple model to describe the evolution of a depositional wax layer on the inner surface of a circular pipe transporting heated oil, which contains dissolved wax. When the outer pipe surface is cooled sufficiently, the growth of a wax layer is initiated on the inner pipe wall, and this evolves to a saturated steady state thickness. The model proposed is based on fundamental balances of heat flow from the oil, into the wax layer, and across the pipe wall. We present an analysis of the model, examine a relevant asymptotic limit in which the full details of the solution to the model are available and develop an efficient numerical method (based on the method of fundamental solutions) for producing approximations of the model solution. The mathematical structure of the model is that of a free boundary evolution problem of generalised Stefan type. © The Author, 2014.

Oil bearing seasonal crops in India:energy and phytoremediation potential

Purpose: A variety of biomass plantations are being raised for energy production. This case study is on energy production potential of seasonal oil bearing crops in India. These crops have the advantage of producing oil (liquid fuel) as well as biomass as agro residue (solid fuel). The purpose of the study is to estimate total energy yields of oil bearing crops and compare with other types of energy plantations. Also oil bearing crops bioaccumulate metals and thus phytoremediate soil. This provides scope for waste water irrigation. Design/methodology/approach: Relevant published papers on energy production by raising oil bearing crops have been analyzed. The effect of waste water irrigation and agronomic practices on increasing productivity is given special attention. Findings: It is shown that the seasonal oil bearing crops such as castor have a high potential to generate energy and this is comparable to energy produced by many perennial grasses. The energy yields of castor under irrigated condition was 196×103 MJ/ha and this is comparable to the reed canary grass which yields 195×103 MJ/ha. Some of the oil bearing crops are also super accumulators of certain toxic metals. Research limitations/implications: In this study, only all the accessible papers on the topic could be analyzed. Practical implications: This case study indicates that raising oil bearing crops such as castor using waste water has many advantages which include high energy yields, utilization of waste water for productive purpose and phytoremediation of soil. Originality/value: The comparison made between various types of energy crops for their energy generation is an original contribution. Findings of economic and environmental benefits by waste water irrigation are also of value. © Emerald Group Publishing Limited.