Uticajni faktori na rad sistema pneumatskog transporta pepela na primeru postrojenja u TENT-B

Abstract

Na blokovima B1 i B2 u TENT-B uveden je novi sistem transporta šljake i pepela (koji se izdvaja u elektrofi ltru, kanalu dimnih gasova i rotacionom zagrejaču vazduha). Transport se vrši do silosa udaljenih oko 700 m. Za pneumatski transport pepela jedan blok ima 2 transportne linije kapaciteta od po 129 t/h. Pri radu blokova sa ugljem lošijeg kvaliteta, niže toplotne moći i većim sadržajem pepela, povećava se količina pepela koju treba transportovati, tako da povremeno dolazi do pojave zagušenja, odnosno pojave taloženja pepela u transportnim cevovodima. Pored toga, dolazi i do abrazivnog delovanja pepela, što dovodi do oštećenja cevovoda i armature. U radu su analizirane karakteristike pepela i uglja koje imaju značajan uticaj na funkcionisanje sistema pneumatskog transporta. Pored osnovnih karakteristika pepela, kao što su nasipna gustina i stvarna gustina, poroznost nasutog sloja, granulometrijski sastav i hemijski sastav (oksidni sastav, sadržaj kvarca i sadržaj amorfne faze), razmatrane su i karakteristike fl uidizacije pepela (brzine fluidizacije) i permeabilnost pepela, koje su od posebnog značaja za odvijanje pneumatskog transporta. Na osnovu nekoliko serija ispitivanja uzoraka pepela (iz procesa sagorevanja u kotlovima TENT-B) obavljenih u Laboratoriji za procesnu tehniku na Mašinskom fakultetu u Beogradu i laboratoriji FC Lafarge u Beočinu, utvrđeno je da je pepeo promenljiv po krupnoći i fi zičko-hemijskom sastavu, što se odrazilo i na karakteristike fl uidizacije. Prema podacima ispitivanja urađena je klasifi kacija pepela na osnovu koje se mogu dobiti određene smernice vezane za odvijanje pneumatskog transporta.

The new transport system for slurry and ash (which separates in electrostatic precipitator, fl ue gas channel and rotary air heater) was introduced on the blocks B1 and B2 in TENT-B. Slurry and ash are transported to silos over distance of approximately 700 m. Ash pneumatic conveying system consists of 2 transport lines with capacity of 129 t/h each. Burning lower quality coal, with lower heating value and higher ash content, results in increased quantity of ash to be transported, which leads to occasional congestions and ash deposition in the transport pipelines. Furthermore, this leads to the abrasive effect of ash and damaging of pipelines and armatures. This paper analyzes ash and coal characteristics which have a significant impact on pneumatic transport system operation. Besides basic characteristics of ash, as bulk and particle density, porosity, particle size distribution and chemical composition (oxide composition, content of quartz and content of amorphous phase), other characteristics that are of particular importance for pneumatic transport operation were taken into consideration, as fluidization characteristics of ash (fluidization velocity) and ash permeability. Based on several series of ash samples examinations (from the combustion process in TENT B boilers), carried out in Laboratory for Process Engineering – Faculty of Mechanical Engineering in Belgrade, and Lafarge Cement Laboratory in Beočin, it was found that the ash had variable size and physicochemical composition, which reflected on the fluidization characteristics. According to the examinations, a classification of fly ash which can provide some guidance related to the performance of pneumatic conveying was made.