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The weak points of plasma waste disposal: the focus on feasibility

According to experts, industrial systems, implemented on technologies using plasma heating will be significantly inferior in terms of specific capital and operating costs of conventional incineration. According to estimates, the practical implementation of such a facility for the processing of solid waste on an industrial scale would cost 600-770 pounds per 1 ton of capacity (calculated annually). At the same time, the capital cost of the plant for the traditional ayer incineration with movable grate 350-450 pounds per 1 ton/year.

In comparisons of the energy efficiency (in terms of the total energy of the combustible components produced syngas) processes and plasma autothermal gasification at temperature of 1126,85°C for one and the same type of fuel (waste), it is shown that an additional energy yield of the synthesis gas, is achieved through the plasma, with existing methods of energy conversion, even without loss of cooling, ballasting of the working mixture in the reactor, etc. It can not cover the actual costs of electricity. It was also found that a further increase in temperature is accompanied by a slight increase in the chemical energy of the synthesis gas, that is, in terms of energy is not effective. Consequently, the use of plasma technology creates additional problems that reduce reliability and efficiency of the entire plant.

Environmental benefits are also doubtful (significantly less impact on the environment and a simplified diagram of the gas cleaning). The resulting synthesis gas has to be subjected to deep cleaning of contaminants which are formed in a reducing atmosphere at high temperatures: hydrogen sulfide, ammonia, phosphine, arsine, hydrogen chloride and others. The efficiency of rapid quenching of the synthesis gas used to destroy compounds such as dioxins and furans has not yet been proven by independent studies.

Let us consider in more detail the most proven technology by Simdean Company, a UK-based plasma waste disposal and industrial waste disposal solutions expert, servicing the domestic and abroad markets. The proposed technology relies on the use of plasma heat to produce synthesis gas (which is subsequently used to generate heat and electricity), a vitrified inert slag (which is converted and inorganic waste which can then be used in industrial production), and metals.

In general, the process of recycling is organised as follows. The waste from garbage trucks are unloaded into a hopper, where they are subjected to a powerful grinding to achieve the required size. Sewage sludge is partially dried (50% RH), and the tire is cut to obtain pieces of the required size for mixing with the solid waste and other waste to the gasification process. Prepared for the processing of waste into the upper part of the gasification reactor used in the gasification technology the company offers is different from other types of gasifiers primarily in construction of plasma torches with adjustable power, located in its bottom part (relative to the gasification zone) and the presence of lumpy coke cushion that prevents mass gasified product to fall below a certain point adjustment gasifier. Due to these differences gasifier provides recycling differ considerably in their morphological and physicochemical properties. The enhanced construction defines the increased efficiency that explains the reasonability of installing the technology at large enterprises with ongoing waste processing.