Small-scale downdraft gasifiers for biomass gasification: A review
TL;DR: In this paper, a review of small-scale downdraft gasifiers for biomass gasification which is focused on design improvements and their effect on the performance of the gasifiers is presented.
Abstract: Downdraft gasifier is very attractive for biomass gasification due to its easy fabrication and operation, and also due to low tar content in producer gas. However, drawbacks such as grate blocking, channeling, and bridging are found in the downdraft gasifiers, typically for feedstock with low bulk density. Another disadvantage is the downdraft gasifiers only suitable for feedstock with low moisture content. The design of the gasifiers is an important parameter that affects their performance. Various works on design improvements have been done for enhancing the performance of the gasifiers. This paper aims to review small-scale downdraft gasifiers for biomass gasification which is focused on design improvements and their effect on the performance of the gasifiers. Many works from previous researchers have been studied and cited. The result shows that the design of the gasifiers is an important parameter in gasification, besides biomass feedstock characteristics and process parameters.
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TL;DR: In this paper, a review deals with the different reactor configurations, operating conditions and catalysts used in each process and compares the different alternatives in terms of H2 production, with emphasis placing on the advantages of the two-step strategy.
308 citations
TL;DR: In this paper, an optimized gasifier and highly active catalyst were proved to be effective for biomass tar elimination, and the tar formation mechanism and the decomposition pathway were also important to advance the optimization of gasification reactors and catalyst design.
Abstract: Biomass gasification converts into syngas, then into other chemicals via Fischer-Tropsch (F-T) synthesis is promising for renewable energy utilization. Although gasification is a sustainable and environmental-friendly technology for value-added utilization of biomass, tar formation is the major problem during the biomass gasification. Tar could condense on the reactor then block and foul equipment. An optimized gasifier and highly active catalyst were proved to be effective for biomass tar elimination. Furthermore, tar formation mechanism and the decomposition pathway were also important to advance the optimization of gasification reactors and catalyst design. This paper summarized the fundamentals, such as gasifier types, Ni-based catalyst, and reaction and deactivation mechanism. This review also sheds light on other excellent catalysts, effective gasifiers and mathematical models of biomass catalytic gasification, and catalyst reaction mechanisms and mathematical models are also discussed in detail. At last, the paper ends with a conclusion and prospective discussion to the latter lab and industrial-scale research.
227 citations
TL;DR: In this paper, a review of the literature on exergetic analysis of the lignocellulose pretreatment process has been presented, focusing on the thermodynamic, economic, and environmental features of the resulting biofuels.
217 citations
TL;DR: In this paper, the authors present the recent progress in the studies on hydrogen production from different kinds of biomass by pyrolysis, gasification and steam reforming without and/or with chemical-looping technologies.
Abstract: Hydrogen production from thermochemical conversion has been considered the most promising technology for the use of biomass, and some novel methods are also being developed for low cost and high efficiency. This review presents the recent progress in the studies on hydrogen production from different kinds of biomass by pyrolysis, gasification and steam reforming without and/or with chemical-looping technologies. Considering potential applications, the Ni-based catalysts made of cheap and earth-abundant elements are especially important for the economically viable hydrogen production from biomass by thermochemical conversion, and can also effectively be compensated for and modified, to some extent, by using extremely low noble metal loading for retaining high catalytic activity, high coke resistance and long-term stability. The catalyst modification strategies of adding other metals, minimizing Ni particle sizes and improving the supports are highlighted. The sorption-enhanced steam reforming (SESR) and chemical looping steam reforming (SE-CLSR) processes with in situ CO2 removal using different reactors have been considered to change the normal equilibrium limits of the water–gas shift (WGS) reaction, and thus increase feedstock conversion and process performances. The auto-thermal operating conditions and CO2 capture during hydrogen production can be achieved by chemical looping processes with cyclic oxidation–reduction of oxygen carriers (OCs). This paper discusses the related issues, challenges and prospects, along with the possible solutions in order to help in the development of efficient hydrogen production from the thermochemical conversion of biomass.
200 citations
TL;DR: In this paper, a review of the development of gasification techniques and the effects of biomass composition, gasifying agents, biomass particle size, operating condition of gasifiers on the gasification efficiency, and type of gasifier are introduced at first and then, the research and development (R&D) and application progresses of the small-scale biomass gasification systems with capacities of 10-200kW over the world are summarized, and the challenges and prospects in the future renewable energy markets are analyzed and discussed.
Abstract: Biomass gasification to provide gas fuels for power generation is considered as one of the best ways for substituting fossil fuels. Large scale unit of biomass gasification with capacity over 2 MW is preferably chosen due to its efficiency to investment ratio even though collecting large amount of biomass takes high cost. To effectively utilize the biomass resources in local and regional areas, it is expected to apply more small-scale biomass gasifiers with a capacity less than 200 kW for a small community or even a family. This will make bioenergy more popular in our daily life. In this review, developed gasification techniques and the effects of biomass composition, gasifying agents, biomass particle size, operating condition of gasification (temperature and pressure) on the gasification efficiency, and type of gasifier are introduced at first and then, the research and development (R&D) and application progresses of the small-scale biomass gasification systems with capacities of 10–200 kW over the world are summarized, and the challenges and prospects in the future renewable energy markets are analyzed and discussed. European, North American and Asia areas are developing and begin to apply various small-scale biomass gasification systems, and African, Latin America, and Oceania countries should be the growing and promising potential regions for the application of this technique in the future, especially in the developing countries. In addition, lowering investment cost and making supporting policies are significantly required to utilize such small-scale renewable energy system.
198 citations
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TL;DR: The conversion of biomass by gasification into a fuel suitable for use in a gas engine increases greatly the potential usefulness of biomass as a renewable resource.
1,179 citations
TL;DR: In this paper, a review of the recent studies in tar treatment from biomass gasification is presented, where the new technologies with their strengths and weaknesses in term of tar reduction are discussed.
Abstract: Biomass gasification presents highly interesting possibilities for expanding the utilization of biomass as power generation using internal combustion engines or turbines. However, the need to reduce the tar in the producer gas is very important. The successful application of producer gas depends not only on the quantity of tar, but also on its properties and compositions, which is associated with the dew-point of tar components. Class 5, 4, and 2 tar become a major cause of condensation which can foul the engines and turbines. Hence, the selectivity of tar treatment method to remove or convert class 5, 4, and 2 tar is a challenge in producer gas utilization. This review was conducted to present the recent studies in tar treatment from biomass gasification. The new technologies with their strengths and the weaknesses in term of tar reduction are discussed.
689 citations
TL;DR: In this paper, the authors present and analyse several gasification models based on thermodynamic equilibrium, kinetics and artificial neural networks, which are used for preliminary comparison and for process studies on the influence of the most important fuel and process parameters.
Abstract: The use of biomass as a source of energy has been further enhanced in recent years and special attention has been paid to biomass gasification. Due to the increasing interest in biomass gasification, several models have been proposed in order to explain and understand this complex process, and the design, simulation, optimisation and process analysis of gasifiers have been carried out. This paper presents and analyses several gasification models based on thermodynamic equilibrium, kinetics and artificial neural networks. The thermodynamic models are found to be a useful tool for preliminary comparison and for process studies on the influence of the most important fuel and process parameters. They have the advantage of being independent of gasifier design, but they cannot give highly accurate results for all cases. The kinetic-based models are computationally more intensive but give accurate and detailed results. However, they contain parameters that limit their applicability to different plants.
680 citations
01 Mar 1988
TL;DR: In this article, the authors present a handbook for the design, testing, operation, and manufacture of small-scale (less than 200 kW (270 hp) gasifiers.
Abstract: This handbook has been prepared by the Solar Energy Research Institute under the US Department of Energy /bold Solar Technical Information Program/. It is intended as a guide to the design, testing, operation, and manufacture of small-scale (less than 200 kW (270 hp)) gasifiers. A great deal of the information will be useful for all levels of biomass gasification. The handbook is meant to be a practical guide to gasifier systems, and a minimum amount of space is devoted to questions of more theoretical interest.
518 citations
TL;DR: In this paper, the effect of size, structure, environment, temperature, heating rate, composition of biomass and ash on auto-gasification is reviewed and further studies are carried out on the effects of heating rate on auto gasification.
Abstract: Studies on the effect of size, structure, environment, temperature, heating rate, composition of biomass and ash are reviewed. Based on the observations reported so far, auto-gasification of biomass by the bio-oxygen and the catalytic ash would be feasible. The auto-gasification may be explained in terms of heterogeneous catalytic reaction. Better understanding of auto-gasification is possible by further studies carrying out on the effect of heating rate on auto-gasification.
402 citations