Reaction Characteristics of Hydrogen-Rich Syngas Production by Sludge/Coal Cogasification Based on the Iron-Based Oxygen Carriers

With the acceleration of industrialization and urbanization in China, wastewater treatment is increasing yearly. As a by-product of wastewater treatment, the gasification of sludge with coal in chemical looping process is a clean and efficient conversion technology. To explore the reaction behavior of cogasification of sludge and coal with iron-based oxygen carriers (OCs) for producing hydrogen-rich syngas, the experiment of cogasification using Fe2O3/Al2O3 as OC in a fluidized bed reactor was conducted. The result showed that the volume percentage of hydrogen (H2) and syngas yield is proportional to the amount of sludge added. The optimal operation conditions were: temperature at 900 °C, the mass ratio of OC to coal at 5.80 and mass ratio of sludge to coal at 0.2. Under this operating condition, the volume percentage of H2 and syngas yield in the flue gas was 75.6 vol% and 97.5 L·min-1·kg-1, respectively. Besides, the OC showed a stable reactivity in the sixth redox cycle with added sludge. However, the reactivity of OC significantly declined in the seventh and eighth redox cycles. It was recovered when the ash was separated. The decrease in the specific surface area of the OC caused by ash deposition is the main reason for the decline in its reactivity. The kinetic analysis showed that the random pore model describes the reaction mechanism of sludge/coal chemical looping gasification (CLG). The addition of sludge can reduce the activation energy of coal CLG reaction, accelerate the gasification reaction rate and increase the carbon conversion.

Influence of the Composition of Solid Fuel on the Equilibrium Characteristics of a Gasification Process in the Mixtures of Oxygen and Carbon Dioxide

The gasification of solid fuels of different elemental compositions in O2/N2 and O2/CO2 mixtures was studied using equilibrium thermodynamic modeling. The dependences of process characteristics (temperature and the yield of carbon residue) on the composition of gasification agent and the stoichiometric ratio were calculated. The addition of carbon dioxide, on the one hand, promoted the conversion of carbon due to an increase in the concentration of gasifying agents and, on the other hand, decreased the process temperature due to an increase in heat capacity and an endothermic effect of the gasification reaction. The efficiency of using O2/CO2 mixtures for the gasification of fuels increased with the carbon content. The highest chemical efficiency of coke and coal gasification was achieved at an initial CO2 concentration of about 40–60 vol %.

Effect of Pyrolysis Reactions on Coal and Biomass Gasification Process

Thermodynamic analysis of a gasification process was conducted assuming that it is composed of two successive stages, namely: pyrolysis reaction followed by a stage of gasification reaction. This approach allows formulation the models of selected gasification processes dominating in industrial applications namely: Shell (coal), SES (coal), and DFB (dual fluid bed, biomass) gasification. It was shown that the enthalpy of fuel formation is essential for the correctness of computed results. The specific computational formula for a wide range of fuels enthalpy of formation was developed. The following categories were evaluated in terms of energy balance: total reaction enthalpy of gasification process, enthalpy of pyrolysis reaction, enthalpy of gasification reaction, heat demand for pyrolysis reaction, and heat demand for gasification reactions. The discussion of heat demand for particular stages of gasification related to the various processes was performed concluding the importance of the pyrolysis stage.

In-site Preparation and Characterization Catalytic- Composite Used for Plastic Waste Degradation to Fuel.

In order to get renewable energy from plastic waste, it should find a pathway or create a new composite that is thermally stable, non-toxic, environmentally inexpensive, and highly efficient. Thus, in our research, we work with composite materials that provide a hetero catalyst designed to crack Polyethylene high Density ( PEHD) , which is composed of Metals (Mn, Ag) in Nano scales , and Graphene impregnated inside the PEG matrix. In order to evaluate fabricated composite catalyst, to be applicable on conversion plastic polyethylene high density to gases yields and solid char carbon using pyrolysis and gasification reaction . the process were carried out inside the fixed bed reactor. Various characteristics have been conducted for final products (gases and black char), further spectroscopic analyses like Ultraviolet–visible spectroscopy (UV) , Cyclic voltammetry (CV) , Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD ), and Thermogravimetric analysis (TGA) were investigated for the new composite.

A Chemical Reaction Can Save Mankind -A Review of Experiment Research on CO2+C=2CO and Application

There are two contents of this article. The first is briefly to review the experiment research on the catalysis mechanism of Carbon Gasification Reaction-CGR(C+CO2=2CO) from 60s -90s. The results show that the catalytic phenomenon is physical phenomenon rather than chemical, and the catalyst does not participate in the chemical reaction. The catalytic activity and selectivity of catalyst are related to the electronegativity or energy level of the catalyst. The second is to clarify the applications of CGR for save mankind. The lime is first proposed to capture CO2 in flue gas of power plant. The lime can be recycled. The coal is used to convert CO2 from cement steel produce into CO, producing both energy and lime and iron. The capture CO2 is used to treat waste such as firewood and plastic, eliminate white pollution. The author considers that using the CGR which has been used for a long time can solve the three problems which people worry about: energy exhaustion, environmental pollution and climate crisis.

Development of new technology for coal gasification purification and research on the formation mechanism of pollutants

Coal-fired power generation is the main source of CO2 emission in China. To solve the problems of declined efficiency and increased costs caused by CO2 capture in coal-fired power systems, an integrated gasification fuel cell (IGFC) power generation technology was developed. The interaction mechanisms among coal gasification and purification, fuel cell and other components were further studied for IGFCs. Towards the direction of coal gasification and purification, we studied gasification reaction characteristics of ultrafine coal particles, ash melting characteristics and their effects on coal gasification reactions, the formation mechanism of pollutants. We further develop an elevated temperature/pressure swing adsorption rig for simultaneous H2S and CO2 removals. The results show the validity of the Miura-Maki model to describe the gasification of Shenhua bituminous coal with a good fit between the predicted DTG curves and experimental data. The designed 8–6–1 cycle procedure can effectively remove CO2 and H2S simultaneously with removal rate over 99.9%. In addition, transition metal oxides used as mercury removal adsorbents in coal gasified syngas were shown with great potential. The techniques presented in this paper can improve the gasification efficiency and reduce the formation of pollutants in IGFCs.

H2-Rich and Tar-Free Downstream Gasification Reaction of EFB by Using the Malaysian Dolomite as a Secondary Catalyst

In this study, Malaysian dolomites as secondary catalysts are placed at the downstream of the fluidized-bed gasifier. Three types of Malaysian dolomites with different elemental ratios of CaO-MgO content denoted as P1, P2, and P3 are investigated with EFB gasification reaction at different cracking temperatures (700–900 °C). The performance of the catalysts with a variation of catalyst to biomass weight ratio (C/B) (0.05 to 0.30 w/w) is evaluated. The findings showed that the total gas yield increased by 20%, hydrogen increased by 66%, along with an almost 99% reduction in tar content with P1 catalyst with the following reaction conditions: gasification temperature of 850 °C, equivalence ratio (ER) of 0.25, and cracking temperature of 900 °C. Malaysia dolomite could be a secondary catalyst to provide a better alternative, tar-free hydrogen-rich gas with the possibility of regeneration and re-use.