Fluidized Bed Co-gasification Research Articles

A parametric study on hydrogen production by fluidized bed co-gasification of biomass and waste plastics

This paper presents a parametric study on hydrogen production potential from biomass and waste plastics via fluidized bed co-gasification technique by using different gasifying agents such as steam, air and CO2. In this regard, a new Aspen Plus model representing this process was developed. For this purpose, first, a comparative feedstock selection between several materials was performed, ultimately identifying the cotton husk (CH) and high-density polyethylene (HDPE) mixture as the most promising choice. Secondly, the study focused on steam co-gasification of CH with HDPE to assess the impact of various factors, including plastic content in feedstock, temperature, steam to feedstock ratio (S/F), and the introduction of gasifying agents, namely air and CO2, next to steam. The analysis mainly examined the influence of these parameters on the composition of syngas, calorific value, and the hydrogen production. Accordingly, it was determined that an increase in plastic content and S/F ratio resulted in higher hydrogen concentration in the syngas, and the maximum quantity of H2 with 1189.3 Nm3/ton feed was produced at 900 °C. In addition, co-utilization of air or CO2 with steam as a gasifying agent deteriorated the system performance regarding H2 yield. Thus, it is expected that the model developed will contribute to the researchers, investors, engineers and policy maker working on the gasification technology for hydrogen production.

Insights of mineral catalytic effects of high ash coal on carbon conversion in fluidized bed Co-gasification through FTIR, XRD, XRF and FE-SEM

This study presents the synergy of high ash coal with different biomass when blended in different ratios for co-gasification using a fluidized bed gasifier. The moisture, CO2, oxygen, hydrogen and numerous other compounds have synergetic effects on the co-gasification because of affinity to heat and prone to reaction. The mineral constituents, discrete mineral species and ion-exchangeable elements present in coal, biomass and bottom ash residue have been identified by XRD, XRF, FTIR and SEM-EDX. The catalytic effects of mineral, major oxides, halides and chlorites content on co-gasification have been assessed. The mineral (e.g. calcite, dolomite, hematite, etc.) present in the high ash coal and biomass plays a catalytic role. Other minerals (e.g. quartz, sulfide, kaolinite and phosphates) negatively influence co-gasification and product gas composition. The positive relationship of CaO, MgO and Fe2O3 with CCE, CGE and increasing heat values also supports major oxides catalytic role. The blend of press mud and high ash coal has given better results due to more Ca, K, Mg and Na elements. SEM microphotographs reveal catalytic effects at the micro-level, indicated by the extensive cracking of hydrocarbon compounds. The empirical models proposed for estimation of catalytic effects of minerals on co-gasification.

Petrographic and chemical reactivity assessment of Indian high ash coal with different biomass in fluidized bed co-gasification

The reactivity of coal and biomass has been evaluated by comparing the optical and chemical changes in feed material prior and after the co-gasification. The proximate, ultimate, GCV, low-pressure N2 sorption isotherm, micropetrography, SEM and EDX spectroscopy analyses are carried out to assess the reactivity of blends of high ash Indian coal and biomass. The relative changes in parameters like surface area, pore size, and pore volume have been correlated with reacted percentage area of coal macerals and cellulose-lignin cellular structures of biomass. The Optimas image processing software is being used to mark the reacted portion of organic constituents and calculated the reactivity percentage. The bottom ash of pure coal has shown the least reacted organic matters, indicating inefficiency of high ash coal due to a large amount of inorganic and inertinite contents that is resisting the oxidation. The reactivity percentage is determined by the petrographic and SEM images, and varies from 36.34 to 99.64% and 6.61–96.22%, respectively. It is summarised that the estimation of percentage alteration of macerals and other micro-organic constituents can be used as one of the practical approaches for the assessment of the reactivity of coal and biomass. The blending ratio 6:4 of coal and press mud has shown the highest reactivity (>99.64%). The values of petrographic and SEM reactivity have shown good correlations with the carbon contents, unreacted vitrinites, mineral matters and biomass remnants. These relations have been taken into account to formulate the proposed petrographic empirically calculated reactivity (RPEC). The focus has also been made to investigate the influence of feed composition on carbon conversion and heating value of the product gas.

Fluidized Bed Co-gasification of Coal and Solid Waste Fuels in an Air Gasifying Agent

The increased need to reduce carbon dioxide emissions to prevent global warming have led to an interest in biomass and solid waste as fuel sources. As a potential renewable energy resource, biomass and solid waste materials are receiving more attention worldwide. A number of techniques and methods have been proposed for reducing gaseous emissions from a fossil fuel conversion thermal system. This paper presents a pilot-scale bubbling fluidized bed gasifier with a diameter of 0.68 m and a height of 1.50 m using an oil burner to heat the bed. This study used four types of biomass materials mixed with coal at different mass composition ratios in an air gasifying agent. The gasification tests were conducted under steady-state at an operating condition that is typical for gasification. The influence that the solid waste and coal ratio had on gasification efficiency was investigated. The gasification efficiency and the carbon conversion efficiency increased when the mass ratio of the solid waste fuels increased.

Fluidized Bed Co-gasification of Algae and Wood Pellets: Gas Yields and Bed Agglomeration Analysis

Algae utilization in energy production has gained increasing attention as a result of its characteristics, such as high productivity, rapid growth rate, and flexible cultivation environment. In thi ...

Fluidized bed co-gasification of biomass and polymeric wastes for a flexible end-use of the syngas: Focus on bio-methanol

Currently a great emphasis is being placed on simplification and cost reduction in the production process of methanol from renewable biomass sources.The experimental results obtained in this work, using a pre-pilot fluidized bed gasifier, demonstrate that the co-gasification of regional biomass residues with PET (polyethylene terephthalate) or tyre wastes may be regarded as a useful strategy to achieve the above goals. In fact, the product gas composition resulting from the presence of the aforesaid polymeric wastes in the fuel blend is such that the gas from the steam reforming unit does not need to be further conditioned in a water–gas shift reactor; the sole carbon dioxide capture process is sufficient to meet the requirements for the downstream methanol production. No significant differences in gas composition were observed moving from the PET to tyre-based pellets, but penalties were noted for the latter concerning tar and particulate generation.

The O2-enriched air gasification of coal, plastics and wood in a fluidized bed reactor

The effect of oxygen-enriched air during fluidized bed co-gasification of a mixture of coal, plastics and wood has been investigated. The main components of the obtained syngas were measured by means of on-line analyzers and a gas chromatograph while those of the condensate phase were off-line analysed by means of a gas chromatography–mass spectrometer (GC–MS). The characterization of condensate phase as well as that of the water used as scrubbing medium completed the performed diagnostics. The experimental results were further elaborated in order to provide material and substances flow analyses inside the plant boundaries. These analyses allowed to obtain the main substance distribution between solid, gaseous and condensate phases and to estimate the conversion efficiency of carbon and hydrogen but also to easily visualise the waste streams produced by the process. The process performance was then evaluated on the basis of parameters related to the conversion efficiency of fuels into valuable products (i.e. by considering tar and particulate as process losses) as well as those related to the energy recovery.

Fluidized Bed Cogasification of Wood and Coal Adopting Primary Catalytic Method for Tar Abatement

The cogasification of coal and biomass represents a valid measure to overcome the limitation of the low energetic density of biomasses and problems arising from use of seasonally produced renewable fuels. The present paper reports on results of fluidized bed cogasification tests carried out with wood/coal pellets (70% wood and 30% coal by mass). With respect to the base case of an inert bed, the presence of catalyst in the bed had a beneficial effect on the concentration of stable gases (e.g., H2, CO2, CO, CH4, and light hydrocarbons) as well as on the efficiency of tar conversion. Upon gasification of wood/coal pellets, the total concentrations of combustible species (CO, H2, CH4, and C2H4) in the syngas always exceeds 45%. Compared to wood pellets, a more energetic syngas (4.5−5.1 MJ/Nm3) is produced with wood/coal pellets. The tar concentration is reduced to around 50% with sintered dolomite and Ni-alumina catalyst with respect to inert bed (quartzite). The gasification of wood/coal pellets gives rise ...

Fluidized-bed co-gasification of residual biomass/poor coal blends for fuel gas production

Fluidized-bed co-gasification of residual biomass/poor coal blends for fuel gas production

Syngas Europa

This article highlights that the European Commission is supporting a wide range of clean coal technology research and development initiatives, including those known as APAS (Activité de Promotion, d'Accompagnement et de Suivi) and Joule (after the 19th-century British physicist James Joule). APAS, a two-year multiple-partner program, was set up to evaluate gasification processes using biomass, sewage sludge, and other wastes as co-feedstocks with coal. The Joule 3 co-gasification initiative was designed to aid European industry to address the technical issues for fluidized bed co-gasification applications. The Joule 2 project for the enhancement of the efficiency of coal-fired power generation systems was undertaken by Siemens and the University of Essen in Germany, and Babcock and Wilcox Espanola in Spain. In the Joule 3 project on advanced cycle technologies, the University of Essen and four partners have investigated measures to reduce costs, enhance efficiency, and provide a basis for an advanced design. The studies also included co-gasification of coal and biomass in an entrained-flow gasifier suitable for IGCCs.