Hydrocarbons still give up to 90 per cent of energy, consumed by the mankind. We try to reduce usage of oil and natural gas, at the same time trying to find alternative energy sources and to make the best use of already known sources.

New technologies of high-temperature processing of solid and liquid hydrocarbons (gasification) by means of an oxidant (mainly air or pure oxygen) help see wood or black coal in a new light. The process of gasification transforms up to 80% of fuel of even the lowest possible quality into synthetic gas, mainly consisting of hydrogen and carbon oxide. Synthetic gas is a promising raw material, which is used in organic synthesis.

Russian physicists from the Institute of Electrical Physics and Power Engineering have made gasification process much easier by suggesting performing it in low-temperature plasma (1200-1500 degrees Celsius) of an electric arch. Using plasma allowed fuller processing of wood with less side products of burning in the end.

Two techniques of gasification currently exist – first is allothermal, and the second is autothermal. When an allothermal technique is used, high temperature is maintained by means of external sources of heat. During autothermal gasification heat comes from the first stage of fuel burning. Gasification speed and synthetic gas quality become better, when temperature goes up, external pressure increases, or oxidant flow is pumped in at a higher rate.

 

 

Russian researchers have used allothermal technique and performed gasification process in relatively cold plasma without applying costly techniques, which require pressure rise and oxidant flow rate regulation. The scientists have built a prototype unit, which can use wood waste or even waste fractions of petroleum products as fuel. A generator of low-temperature plasma was prepared for working mode (1500 degrees Celsius) during eight hours, and then was filled with wet wood. Hydrocarbons began to be partly oxidized inside the generator chamber, and the oxidation process was finished in the purification system for synthesized gases. Using mentioned technology reduced the amount of unreacted carbon atom to 20-50% compared to existing industrial autothermal technology. Moreover, costs for maintaining high temperature inside the reactor were cut for 15-45%. Another advantage of the technology used is that carbon dioxide (CO₂) concentration in resulting synthetic gas was low. Productive capacity of the prototype unit was about 70 kilograms per hour.

The fact that raw material (wood) was really wet, had no effect on the yield of synthetic gaseous product. Moreover, the process appeared to be much more (10%) effective, that it has been calculated before the experiment. Researchers explained these results with minor mistakes made during estimation of wood moisture content. Therefore, Russian researchers have not only suggested an effective technique for better gasification of hydrocarbon fuel, but also a non-waste, ecologically friendly way of utilization of wood wastes.