Cosmin Marculescu

Analysis of biomass and waste gasification lean syngases combustion for power generation using spark ignition engines

The paper presents a study for food processing industry waste to energy conversion using gasification and internal combustion engine for power generation. The biomass we used consisted in bones and meat residues sampled directly from the industrial line, characterised by high water content, about 42% in mass, and potential health risks. Using the feedstock properties, experimentally determined, two air-gasification process configurations were assessed and numerically modelled to quantify the effects on produced syngas properties. The study also focused on drying stage integration within the conversion chain: either external or integrated into the gasifier. To comply with environmental regulations on feedstock to syngas conversion both solutions were developed in a closed system using a modified down-draft gasifier that integrates the pyrolysis, gasification and partial oxidation stages. Good quality syngas with up to 19.1% - CO; 17% - H2; and 1.6% - CH4 can be produced. The syngas lower heating value may vary from 4.0 MJ/Nm(3) to 6.7 MJ/Nm(3) depending on process configuration. The influence of syngas fuel properties on spark ignition engines performances was studied in comparison to the natural gas (methane) and digestion biogas. In order to keep H2 molar quota below the detonation value of ⩽4% for the engines using syngas, characterised by higher hydrogen fraction, the air excess ratio in the combustion process must be increased to [2.2-2.8]. The results in this paper represent valuable data required by the design of waste to energy conversion chains with intermediate gas fuel production. The data is suitable for Otto engines characterised by power output below 1 MW, designed for natural gas consumption and fuelled with low calorific value gas fuels.

Two-phase Pyrolysis Modelling OfWooden Waste

Pyrolysis technology has been demonstrated in recent researches as one of the most effective and environmentally friendly methods for solid wastes pretreatment and energy utilization. Pyrolysis is a process wherein organic materials are exposed to thermal treatment in the absence of an oxidizing agent, resulting in a solid (char), liquid (tar and bio-oil) and volatile gases (CO, CO2, CH4, and H2). A two phase (solid-gas) equilibrium model is proposed in this work in order to simulate the pyrolysis process of wooden biomass (spruce sawdust). The model is able to predict the amount of solid char, the yields and the chemical composition of pyrolysis gas for different process temperatures. In this case, process simulations were done for 600oC and 800oC. Aiming the model validation, an experimental campaign was carried out using batch-scale pyrolysis reactor. The simulation results have shown a good agreement with the experimental once.

Dielectric characterization of bentonite clay at various moisture contents and with mixtures of biomass in the microwave spectrum

ABSTRACT This study assesses the potential for using bentonite as a microwave absorber for microwave-assisted biomass pyrolysis based on the dielectric properties. As bentonite is a hygroscopic material, the effect of bound water content on dielectric properties was addressed in this study. Dielectric properties of bentonite at different moisture contents were measured using a coaxial line dielectric probe and vector network analyser in the microwave frequency range from 0.2 to 4.5 GHz at room temperature. Further, dielectric properties of mixtures of bentonite with biomass were measured from 1.5 to 20 GHz as mixtures of bentonite with biomass could have microwave processing applications such as the thermochemical conversion of biomass to biofuel. Both dielectric constant and dielectric loss factor increased linearly with increasing moisture content. Measurements on biomass and bentonite mixtures show a quadratic increase in dielectric constant and loss factor with increasing bentonite content and with moisture contents ranging from 9.5% (pure bentonite) to 11.4% (pure biomass) wet basis. At 915 MHz, dielectric constant ranged from 2.0 to 6.2 and dielectric loss ranged from 0.2 to 2.7, respectively. At 2450 MHz, dielectric constant ranged from 1.8 to 5.1 and dielectric loss ranged from 0.7 to 2.6, respectively.