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The demand for energy to sustain the economies of industrialized and developing nations has led to the search for alternatives to the use of imported petroleum fuels. Instability in the Middle Eastern countries, the major exporting sources for these petroleum feedstocks, has led to questions of availability in addition to the economic issues. While coal and nuclear technologies are currently the leading sources for reduction of petroleum imports, wood and other biomass feedstocks have garnered attention as to their potential as additional alternatives. Studies have shown that the amount of biomass waste resources in the United States, if converted effectively, could significantly reduce the need for petroleum imports. The focus of this research is to examine a patented, entrained flow, steam gasification process for the ability to produce gaseous components suitable for use as a fuel or in subsequent conversion processes, such as production of alcohol or diesel. The primary gases which are examined are hydrogen, carbon monoxide, carbon dioxide, and methane. The process is characterized using a nominal 3 ton (wood) per day “pre-pilot” facility and a nominal 30 ton (wood) per day “pilot” unit. Each of these gasification systems are characterized for production of primary gases using wood as the feedstock. As part of these characterizations, “equivalent” temperatures and residence times were developed that better described the process operations. An important consideration in the development of any industrial process is the ability to scale-up from a conceptual, or preliminary, scale to a size capable of commercial operation. As such, the characterizations of the two gasification systems were compared and relationships were developed to allow predictions of product gas compositions based on gasifier size as well as operating parameters.

Present integrated gasification combined cycle (IGCC) systems demonstrate high system efficiency and impressive environmental performance, giving them an edge over conventional pulverised fuel power stations. A key area in the development of IGCCs is hot fuel gas clean-up (HGCU). Fuel gas cleaning at elevated temperatures reduces thermal efficiency losses associated with gas quenching in conventional cold gas cleaning methods. Current hot gas desulphurisation techniques focus on the use of regenerable metal oxide sorbents, however the long-term sorbent performance issues have yet to be fully addressed. A fresh and radical approach may provide the key to overcoming the inherent limitations associated with metal oxide sorbents. A molten tin irrigated packed bed scrubber adopted in this research project is one such innovative way forward in HGCU. The hot scrubber offers the prospect of a multicomponent clean-up device. High-temperature sulphur removal takes place via absorption of H2S (and COS) into molten tin whilst discrete molten tin droplets and rivulets on the packing surface act as solid particulate collectors. The primary aim of this research project was to investigate the workings of a small-scale room temperature packed bed scrubber operating under non-wetting flow conditions analogous to the molten tin irrigated scrubber. Water irrigation of low surface energy packings simulated the nonwetting flow of liquid metals. The air-water analogue of the liquid metal scrubber provided the platform for hydrodynamics (flow visualisation, flooding and liquid holdup), particulate removal and mass transfer studies under non-wetting flow conditions. The performance of a small air lift for water circulation through the column was also investigated. These cold studies offered insight into the operation and performance of the liquid metal hot scrubber. Prior to the cold gas scrubber studies, preliminary small-scale gasification tests on petroleum coke samples were performed to investigate the effect of molten tin on H2S in the product fuel gas. The tests provided actual experimental evidence of the possibility of sulphur removal by molten tin in a gasification environment. It was shown that the maximum possible size of a liquid droplet hanging from a non-wetting spherical solid surface could be predicted from the liquid surface tension and density based on force balance. The mobility of static holdup in a non-wettable packed bed has been demonstrated, this being due to the tendency for the liquid to form discrete droplets rather than spreading films. Existing flooding and liquid holdup correlations that hold for conventional wettable packed beds were shown to be inadequate where non-wetting systems were concerned. Summary hence alternative methods applicable to the latter were sought. The introduction of a non-wetting tendency factor based on the ratio of the solid critical surface tension to the liquid surface tension, enabled the flooding capacities of non-wetting systems including those of this study to be predicted using Sherwood et al. 's graphical flooding correlation. The total volumetric liquid holdup was well correlated against the bed pressure drop, true gas velocity and gas density, offering the prospects of predicting holdup for systems using the same spherical packing. In general, the water-irrigated packed bed showed good hydrodynamic similarities to liquid metal systems, suggesting a dominating influence of liquid-solid contact angle which overrides striking differences in liquid physical properties. The performance of the small air lift pump was unaffected by varying the number of gas ports on the injector without any change to the hole size. The operating curve of the air lift pump could be predicted with good accuracy using momentum balance and two phase flow theory, provided that all major pressure losses in the system were accounted for, including notably the downcomer friction losses and accelerative effects. The non-wetting packed bed scrubber demonstrated impressive dust removal performance. Total separation efficiencies as high as 99.6% and cut sizes approaching submicron were achieved. Dust particles larger than about 6.5 um can be separated to efficiencies greater than 98%. Complete particle separation was achieved in all cases for dust particles larger than 16 J..lm. Particulate removal in a packed bed of spheres under non-wetting flow conditions has also been modelled using computational fluid dynamics (FLUENT). Simulation results showed that particle separation efficiency increases with particle size and density, but is unaffected by particle concentration. The predicted particle size corresponding to 98% efficiency is about 40 J..lm. In mass transfer, the height of the gas film transfer unit of various non-wetting spherical packed bed systems including those of this study was correlated successfully against the gas phase Reynolds number, the liquid superficial velocity and the packing diameter. Results from the cold gas scrubber studies have offered insight and understanding into the workings and development of the liquid metal packed bed gas scrubber. Findings and correlations derived from the water model studies, occasionally complemented by data from other non-wetting systems, have provided the means to predict the hydrodynamics, particulate removal capability and mass transfer performance of the liquid metal based gas scrubber. The pilot unit of the hot gas scrubber has been designed and fully constructed. The high temperature gas cleaning facility is ready for commissioning.

No description available.

The utilization of biomass sources can reduce greenhouse gas emission. Presently, biomass is being considered as a potential energy resource to substitute fossil fuel for large-scale power generation through combustion as well as a chemical feedstock. Gasification can turn biomass into convenient product gas that could be used for both energy conversion and chemical production. Biomass gasification is being recognized as an alternative to combustion for the production of clean energy and provision of syn gas for production of chemicals. However, major limitation of the biomass gasification is the tar produced during the process and the high-energy cost associated with its removal from the product gas. Torrefaction is a new pretreatment method for biomass that has positive features such as reduced the storage, transportation cost, increased energy density, easier grinding. The torrefaction process partially removes the low quality volatiles matter thereby making the gas cleaning simpler and increasing energy density of the biomass. Furthermore, it lowers the O/C ratio of biomass fuel making it more favorable for gasification. To examine the above potential steam-gasification of raw biomass char and torrefied biomass char was investigated and studied their product gas composition and its other attributes. In this study, poplar wood was torrefied at 250oC and 275oC for 1 hour and gasified at different gasification temperatures (700-950oC). Measured and analyzed syngas gas yield, syngas composition and heating value. The kinetics of the process was also studied and it showed that torrefied (250oC with 1 hour residence time) biomass char had activation energy of 92.30 kJ/mol. Furthermore, SEM analysis of the char produced from the torrefied biomass and raw biomass was conducted to observe any difference in the microstructure their structure. The gasification experiments indicated that torrefied biomass produces slightly higher concentration of hydrogen and lower concentration of carbon dioxide than untreated biomass. Furthermore, this study showed that torrefaction has minor reduction in syngas yield, but major reduction in tar production. Overall combination of torrefaction and gasification of biomass is a promising technology for the future energy generation.

Thesis (M.S.)--Ohio University, November, 1981. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, August, 1983. / Title from PDF t.p.

Thesis (Ph. D.)--University of Newcastle, 1996. / Department of Chemical Engineering. Includes bibliographical references (leaves 243-255). Also available online.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains vi, 184 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 82-84).

In 2004 the Department of Chemical and Process Engineering (CAPE) at University of Canterbury began a programme to investigate using biomass gasification integrated combined cycle (BIGCC) technology to convert waste products and residues to useful energy for the wood processing sector. This research was conducted as a part of Objective Two of the programme to develop gasification and gas cleaning technology. This project involved commissioning and characterising the operation of the Fast Internal Circulating Fluidised Bed (FICFB) gasifier and comparing its operation with a more conventional up-draught process owned and operated by Page Macrae in Mount Manganui. The wood derived gas composition of each gasifier was measured using gas chromatography and these compositions were used to calculate lower heating values (LHV). The CAPE FICFB gasifier has proven to produce successfully a gas with a lower heating value of 10400-12500 kJ/Nm³. The Page Macrae gasification process produces a low quality gas with a lower heating value of 4100-5100 kJ/Nm³. This is much lower than the CAPE gasifier since the oxidant used in the up-draught gasification process is air and the product gas is diluted by nitrogen. The Page Macrae gasification system combusts wood derived gas to produce steam for a laminar veneer lumber (LVL) processing plant so gas quality and heating value are less important than in electrical production applications. Reducing the nitrogen content of the CAPE product gas will increase the heating value of the gas. Improvements to the boiler system will reduce the amount of air required for gasification and hence reduce the nitrogen content. Further improvements to gas quality can be gained from a change in the fuel feed point from on top of the gasification column's bubbling fluidised bed to the side of the bubbling fluidised bed. The CAPE gasifier is much more complicated and requires specialised operators but produces a gas suitable for gas engine and gas turbine technology. Overall the CAPE gasification system is more suited to BIGCC applications than the Page Macrae process.