Thesis (M.E.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 132-135). Also available via the World Wide Web.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Realff, Matthew; Committee Member: DeMartini, Nikolai; Committee Member: Muzzy, John; Committee Member: Sievers, Carsten.

The poultry industry in Europe is vast and proper waste management is required in order to comply with environmental regulations. As a result, poultry litter represents a potential fuel candidate for thermal conversion technologies since it is an available source. Therefore, a process for the gasification of poultry litter is examined in this study. This process integrates a fluidised bed gasifier with a gas turbine with the aim of generating combustibles gases for energy production. This resulted in a viable solution for a small scale system to be installed on-site the biomass source. The system allows the treatment of waste with the additional benefit of generation of energy, and is suitable for a poultry farm to avoid the transportation of litter to centralised plants. Among the by-products generated during gasification, such as NOx, SO2, and fly ash, tar is a major issue when implementing this technology because tar can cause operational problems as a result of the possible formation of aerosols and soot formation due to repolymerization. A process simulation using Aspen Plus was used to evaluate four levels of integration. The equilibrium model was applied to evaluate integration schemes involving recuperation of energy from the gas turbine exhaust gases. The recuperation of residual heat to preheat air and product gases was performed with the aim of achieving the highest electrical efficiency. For the conventional "atmospheric layout", the fuel gases have to be cooled down before being compressed to the desire pressure, which causes to waste energy from the hot fuel gases. The benefit of the "pressurised layout" is that all process stages can be maintained hot. Process efficiency analyses showed that even when the "atmospheric layout" was set with energy recuperation, the "pressurised layout" delivered higher efficiencies with or without the energy recuperation into the gasifier. After a bibliographic review, the lignin content of biomass was concluded responsible for tar formation because of its aromatic nature. As lignin components, guaiacol, vanillin and catechol were chosen as tar precursors due to its presence in lignin structure. A reaction mechanism and its corresponding kinetics were derived. This mechanism was based on the three-lignin unit decomposition into lighter molecules and greater aromatic rings. Some of the tar products were involved in combustion and/or steam gasification reactions. The tar reaction mechanism was introduced into the kinetic model for the gasification of poultry litter. The results showed agreement with experimental work from previous reports for the evolution of primary tars. However, the model overestimated the total tar concentration. When the model was compared with the equilibrium model, the trends of the main product gases agreed as the air:fuel ratio was varied.

Hydrogen as a clean energy carrier has drawn great attention. Production of H2 from sustainable bio-oil is considered an alternative for conventional fossil fuel based energy system, since the overall process of bio-oil converting to H2 ideally is carbon-neutral and hence environmental friendly. This study focuses on developing an adequate catalyst for bio-oil steam reforming to produce H2. Ruthenium and/ or nickel based catalysts supported on alumina, ceria-alumina or ceria-silica were synthesized by sol-gel method or incipient wetness impregnation and characterized using BET Surface area analysis, Powder X-Ray diffraction (XRD), Temperature Programmed Reduction (TPR) and Scanning Electron Microscopy (SEM). Steam reforming of selected model compounds, n-propanol, glycerol and acetic acid, was investigated in a fixed bed tubular flow reactor over the prepared catalysts at 450 or 500 °C. The effects of support nature, preparation method, catalyst composition and reaction temperature on the steam reforming activity and stability of catalysts were studied. Catalysts showing better performance in terms of reactant conversion and H2 yield were selected for investigating the steam reforming of an acetic acid/glycerol aqueous mixture, consisting of acetic acid and glycerol with a weight ratio of 3/7 similar to a bio-oil generated from fast pyrolysis of cellulose. The steam-to-carbon ratio (S/C) and the flow rate of feed were constant at 4 and 0.1 ml/min, respectively. The effluent gas was monitored by GC/TCD and the evolution of carbon conversion and product gas distribution as a function of time was studied. Among all catalysts investigated, the one with nominal composition A10C10N1Rnc showed the best performance in steam reforming at 500 °C as indicated by higher and more stable H2 yields achieved regardless the reactant used. In order to investigate the sorption-enhanced steam reforming, three CaO-based CO2 absorbents were synthesized: two derived from calcium acetate with or without MgO support, noted as CAM and CA, respectively, and the other MgO-supported one derived from calcium d-gluconate, denoted as CGM. Results from the 15-carbonation/regeneration-cycle test suggested that the MgO-containing absorbent CAM has the highest CaO molar conversion and stable CO2 absorption capacity. Though significantly higher CO2 absorption capacity was shown from absorbent CA in the first one cycle, CA absorbent soon lost most of the CO2 absorption capacity due to severe sintering. In addition, the CO2 absorption capacity of absorbent CGM might be underestimated due to insufficient carbonation time. The A10C10N1Rnc catalyst and the CAM absorbent were applied in the steam reforming of acetic acid/glycerol mixture at 500°C. However, no significant improvement can be observed in the presence of absorbent CAM

Production of hydrogen from biomass steam gasification can be enhanced by using calcium oxide sorbents for CO2 capture in the gasifier. Calcium looping suffers from two main drawbacks: the need for high-purity oxygen in order to regenerate the sorbent under oxy-fuel combustion conditions and the loss of sorbent reactivity over several cycles due to sintering of pores upon calcination at high temperatures. One method of addressing the issue of oxygen supply for calcination in calcium looping is to combine the calcium looping and chemical looping processes, where the heat produced by the reduction of an oxygen-carrier by a fuel such as natural gas or gasification syngas, drives the calcination reaction. The technologies can be integrated by combining an oxygen carrier such as CuO with limestone within a composite pellet, or by cycling CuO and limestone within distinct particles. The goal of this project is thus to investigate the different sequences of solids circulation and the cyclic performance of composite limestone-CuO sorbents under varied operating conditions for this novel process configuration. Using a thermogravimetric analyzer (TGA), it was found that using composite CaO/CuO/alumina-containing cement pellets for gasification purposes required oxidation of Cu to be preceded by carbonation (Sequence 2) as opposed to the post-combustion case where the pellets are oxidized prior to carbonation (Sequence 1). Composite pellets were tested using Sequence 2 using varying carbonation conditions over multiple cycles. While the pellets exhibited relatively high carbonation conversion, the oxidation conversion underwent a decrease for all tested conditions, with the reduction in oxygen uptake particularly drastic when the pellets were pre-carbonated in the presence of steam. It appears that the production of a layer of CaCO3 fills up the pellets pores, obstructing the passage of O2 molecules to the more remote Cu sites. Limestone-based pellets and Cu-based pellets were subsequently tested in separate CaL and CLC loops respectively to assess their performance in a dual-loop process (Sequence 3). A maximum Cu content of 50% could be accommodated in a pellet with calcium aluminate cement as support with no loss in oxidation conversion and no observable agglomeration.

This diploma thesis deals with the use of CO2 in gasification of biomass. The theoretical part is focus on description of gasification process and gasification reactors. The next part descripes the influence of the gasifitation medium composition on the properties of the generated gas. The experimental part is devoted to gasification of biomass on a fluidized bed generator, where the effect of CO2 concetration in the gasification medium on the properties of the generated gas is investigated. In the final part is the evaluation of the results.

Using biomass gasification to produce combustible gas is one of the promising sustainable energy optionsavailable for many countries. At present, a few small scale community based power generation systemsusing biomass gasifiers are in operation in Sri Lanka. However, due to the lack of proper knowledge, thesesystems are not being operated properly in full capacity. This stands as an obstacle for further expansionof the use of gasifier technology.The objective of this study was to identify the most influential parameters related to fuel wood gasificationwith a down draft gasifier in order to improve the gasification processes.A downdraft gasifier of 10kW electrical capacity was used to study the effect of equivalent ratio (Actual airfuel ratio to Stoicheometric air fuel ratio: ER) on the specific gas production, the heating value of gasproduced and the cold gas efficiency using three throat diameters (125mm, 150mm and 175mm). Six trialswere carried out for each throat diameter by varying the supply air flow to change the ER. The gassamples were tested for their compositions under steady state operating conditions. Using mass balancesfor C and N, the cold gas efficiencies, calorific values and the specific gas production rates weredetermined.The results showed that with all throat diameters the calorific value of gas reduced with the increase ofER. The cold gas efficiency reduced with ER in a similar trend for all three throat diameters. The specificgas production increased with ER under all throat diameters.Calorific value and specific gas production are changing inversely proportional manner. The ER to beoperated is depends on the type of application of the gas produced and engine characteristics. When alarge heat is required, low ER is to be used in which gas production is less. In the opposite way, when alarge amount of gas is needed, higher value of ER is recommended.

This work is dealing with the utilization of biomass feed stocks and wooden residue for gasification process to produce syn-gas suitable for the implementation of power plants for electricity generation and problem of gas production suitable for further chemical and energy purpose discussing the suitable practical purification methods, given that the complexity of theme and project which carried out through detailed analysis. Since the obtained gas has many types of unwanted contaminants. It was necessary to derive an effective cleaning method for gas purification from chemical contaminants especially tars components. The discussion of the definitions and methods for the determination of gas unwanted components and their removal technologies on the basis of the knowledge of data, collecting and analysis carried out through an experimental massive approach. The theoretical analysis of the gasification process for an effective tar reduction in the produced gas has been studied as well. Since the quality requirements for internal combustion engines, gas turbines and fuel cells using the primary measurement methods cannot be achieved for gas production, this work aimed removing different particulates and tar. The main emphasis is placed on the methods of high cleaning taking in account the chemical and thermal specifications of the gas which is based on the utilization of three different kinds of carbon materials successfully and efficiently char coal, black coke and active carbon for tar removal which has a major impact on the process parameters. The analysis was responding with the mechanism and the techniques of minimizing the resultant allowable concentration by using a suitable materials and verifying the operation conditions without affecting the gas thermal efficiency. The highlights of the theoretical and experimental work has been drawn up by a high concept cleaning allowing the production of a pure gas having a quality that meets the modern technical requirements for electricity generation. Functionality the most efficient cleaning methods were based in the current project for tar reduction on the quantity of tar removed, the materials used for tar cracking and the conditions of the experimental work as well. For a successful application, some proposals have been settled for industrial applications of gas cleaning.

Gasification of biomass is a one of the several technologies for energy production from biomass. Biomass is a promising renewable source of energy and is in a centre of attention of energy industry not only in the Czech Republic, but also in the EU and in the world. Gasification is a thermo chemical transformation of fuel with access of understoicheiometric amount of oxidizer which produces gas of low heating value. Its main combustible components are hydrogen, carbon dioxide and methane. Produced gas may be further used in power and heating plants. Besides combustible and neutral components, gas also contains pollutants such as sulphur compounds, chlorine compounds, ash and tar. It is tar which is considered to be the underbelly of gasification as it causes, along with ash, fouling in transport tracks and terminal equipment, and blocks direct application of gas. This dissertation thesis presents design of filter for elimination of tar from the gas generated in fluid gasification equipment. This work is closely related to current research at Energy Institute at Faculty of Mechanical Engineering at Brno University of Technology. First part deals with theoretical background of this issue. Biomass properties are mentioned in relation to gasification. Types of gasification equipment are described and principle of gasification including chemical reactions is given in detail. Special part is dedicated to pollutants in the gas, especially to production of tar and its properties, which is important for consequent work. Main focus is on possibilities of catalytic cleaning of gas from tar. Principle of tar decomposition is described and types and properties of catalysts are given. Part of the thesis tackles the issue of real operations and loss of efficiency of catalyst due to sulphur compounds, sintering and carbon fouling. Based on experience and analysis in the first part of the thesis, concept of elimination of tar from gas was laid out. In addition to that, method for measurement at Biofluid 100 experimental unit was outlined and filter for testing of industrial catalysts using metal was designed. Series of experiments were further conducted in order to find out efficiency of three opted catalysts for tar decomposition. Results of these experiments are described in detail and assessed in the conclusion of this thesis which also contains outline for economic assessment of method of gas cleaning using catalysts.

Due to the advancement of global warming internationally, increasing emphasis is being placed on the environmental accountability of everyone from countries to processes. This study presents novel research on the environmental impacts and economic trade-offs for a processes co-producing electricity, methanol, dimethyl ether (DME) and Fischer Tropsch (FT) fuels from different feedstock ratios of biomass, natural gas, and nuclear hydrogen generated through a CuCl cycle are analyzed for operation in Canada to produce transportation fuels. This study also considers the use of carbon capture and sequestration (CCS), the location of the plant in either Ontario and Alberta, and the input ratio of the feedstocks. This combination of carbonless heat and a “carbon neutral” biomass feedstock would contribute to the net reduction of greenhouse gas (GHG) emissions. In Part I of this work, the model for this BGNTL process was developed. This work expands on the model and evaluates the economics and environmental impacts this plant would have in both Ontario and Alberta based on their local costs, resource availability, and current electricity grid contributions. The analysis investigates the effectiveness of the emission reduction of the products and processes when compared to their cost. It is shown that an increase in the ratio of biomass to natural gas in feedstock, the use of a solid oxide fuel cell (SOFC), and the production of additional electricity while reducing the emissions of the process, increases the cost of CO2e avoided. The results show that the BGNTL concept can be an economically attractive way of reducing net transportation sector GHG emissions in both Ontario and Alberta in meaningful quantities. Optimal cases for both biofuel and FT fuel production contain a single output fuel production process, produce fuels over electricity where possible, and use a gas turbine (GT) for the electricity production that occurs. / Thesis / Master of Engineering (MEngr) / This paper examines a system producing a combination of transportation fuels including diesel, gasoline, methanol (MeOH), dimethyl ether (DME) and electricity from biomass, natural gas and hydrogen. The design of the system units used in the process was done in a previous study, this work expands on the design looking specifically at locating the plant in Ontario and Alberta for their raw resources, electricity grids, and current production methods of fuel. Variations of the plant are compared to each other and current fuel and electricity production with an aim of reducing the cost and emissions created while producing and using the fuels. It is found that increasing the amount of biomass used significantly reduces the emissions but does not create a competitive process due to how expensive it is. Results show that this type of system can decrease transportation sector emissions with a similar additional cost as other current alternatives.