Numerical Investigation of Supersonic Hybrid Argon–Water-Stabilized Arc for Biomass Gasification
This paper presents a numerical simulation of temperature and flow fields in the discharge and near outlet regions of the hybrid argon-water-stabilized electric arc. The calculations for an argon mass flow rate of 0.450 g ldr s-1 reveal the transition from a transonic plasma flow for 400 A to a supersonic one for 600 A with the maximum Mach number of 1.57. The comparison with available experimental data for 400 A shows satisfactory agreement.
Pyrolysis of waste using a hybrid argon–water stabilized torch
Abstract An experimental plasmachemical reactor equipped with the novel IPP-ASCR hybrid gas–water stabilized DC torch (160 kW) has recently been started at IPP Prague for the innovative and environmentally friendly plasma treatment of waste streams with a view to their sustainable energetic and chemical valorization and to a reduction of the emission of greenhouse gases. Since the process energy is provided by direct heat transfer from plasma, gases of widely varying chemical composition may be used. The use of electrical energy also reduces the gas flows and requirements for exhaust-gas treatment, and offers control over the chemistry. Pyrolysis of biomass was experimentally studied using wood chips as a model substance. Syngas with a high content of hydrogen and CO was produced. The influence of adding CO 2 for increase of oxygen content in the reactor was investigated.
Spatial distribution of chemistry, structural features and phases in thermal spray deposits
Structure and phase composition are important parameters deciding on properties of thermal spray (TS) deposits-e. g. [1], [2]. This work points out that the spatial distribution of phases, structural features and chemicalelements is not necessarily uniform over the entire TS deposits. Moreover, non-uniform distribution can be found even in individual splats forming a deposit. Therefore two parameters were introduced: 1) macrohomogeneity across a deposit; 2) microhomogeneity across an individual splat. Scanning electron microscopy combined with X-ray microanalysis was used for detail study of several examples of various ceramic (silicates, titanates, oxides) and metal deposits made by thermal spraying. Microhomogeneity was studied on single splats and variation of structure and chemical composition was demonstrated on chromia based ceramics, AlSi metal deposits and others. Non-homogeneity is probably connected to the modes of solidification. Variation of phase composition, degree of porosity, crystallite size and distribution of chemical elements across deposits-macrohomogeneity-is then demonstrated for several materials, like CaTiO 3 based powders, zircon, alumina [3], etc. It is interesting to note, that some materials are more sensitive, while others are practically insensitive (e. g. CaTiO 3 ).