CHALLENGES AND OPPORTUNITIES OF UTILIZATION OF ASH AND SLAG WASTE OF TPP (THERMAL POWER PLANT). PART 2

Abstract

For existing and already constructed coal TPP plants, known methods of utilization of fly ash and slag wastes (FASW) may be in de­mand when all emerging environmental and economic risks are taken into account. But for the new power generating source when choosing coal combustion technology, it is necessary to increase the significance of the environmental component of the project more essentially. It is known that the most promising technologies for coal combustion, which increase environmental safety exactly by burning, are technolo­gies based on a circulating fluidized bed. These technologies can sig­nificantly reduce sulfur and nitrogen oxide emissions behind the boiler, but the solution to the problem of flay ash and slag waste remains at the same level. It is proposed to solve the problem of FASW utilization during the implementation of new energy projects or when replacing the decommissioning capacities of coal generation by replacing the method of coal combustion in a stream or fluidized bed with meth­ods of burning solid fuel in a bubbling slag melt. The descriptions and schemes of these methods are given. The comparison of the main qual­itative technical and ecological parameters of pulverized coal combus­tion and technologies of coal combustion in slag melt is presented. The development of coal generation is expected in two main areas: coal combustion with increasing steam parameters and gas generation with a combined cycle of electricity generation: steam and gas, based on the gasification of solid fuels. These directions will allow achieving electric efficiency of steam-power plants from 30 – 36 %, up to 44 – 45 % on supercritical steam parameters, and using a combined steam-gas cycle up to 50 – 55 %. A technological scheme of gasification of coal in a slag melt is proposed, which increases the electrical efficiency of the installation. The ecological and economic efficiency of the gasifica­tion method for solid fuel and the simplicity of the production of slag products by casting are shown. The quality of cast slagstone products is much higher than similar cement-sand products with the addition of fly ash, and the ease of transition from one casting mold to another allows quickly responding to market demands.