TECHNOLOGICAL SCHEMES OF PNEUMATIC ASH REMOVAL OF THERMAL POWER PLANTS

Abstract

The article covers existing technological schemes of pneumatic ash removal on thermal power plants, which provide a dry state of ash for its further utilization in various industries. In order to simplify and improve the schemes of pneumatic ash removal and to improve the economic indicators of pulverized-coal fired boilers of TPP (thermal power plants), I.Sikorsky Kyiv Polytechnic Institute specialists developed a new scheme of ash removal from under the electrofilters and designed new air-assisted feeders. The scheme provides a dry method of ash removal from under the cells of the electrofilters with smoke gases of the boiler that are taken from the pneumatic transport system of the smoke exhauster, discharged to the bag filter and are transported by the gas blower to the collector, which feeds on the air-assisted feeders. Keeping of gas temperature higher than Dew point is provided by the heater. After liquefaction in the cells of air-assisted feeders ash coal-air mixture is driven through pipelines to the collector with installed injectors and comes into dust separating cyclone, in which coal-air mixture is divided into two streams. Flue gases, cleared of ash, return to the guide box of the electrofilter, reducing the temperature at its input and raising efficiency of the plant. The separated ash is shipped through the pipeline to the consumer or sent to silo for storage. Compared with the known technological schemes of pneumatic ash handling, the new scheme differs as follows: airless transportation of ash; utilization of heat of waste flue gases from boilers and their dust removal to the normalized inficators of the Directive 2010/75/EU; increase in the efficiency of the electrofilter due to mixing of flue gases at the inlet of the electrofilter; low specific energy costs (absence of compressor and fan); short pipeline ties, compactness; low wear and tear of equipment (the speed of dust particles up to 8 m/s). The scheme of transportation of dry ash from under electrofilters of thermal power plants will allow to increase the efficiency of Ukraine's coal-fired TPPs; maximize the disposal of ash as valuable product, receive profit from its sales and solve problems of environmental protection.