The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investi...The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. One coefficient of Meij was also improved to more directly show element enrichment in combustion products. These elements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2 Cr has properties of both group 1 and 3 In addition, the smaller diameter of fly ash, the more relative enrichment of trace elements(except Mn). The fly ash showed different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not always improve the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Trace elements should be classified in accordance with factors.展开更多
Peoples life is closely related to the building, but the drainage engineering problems in the construction process has become a key problem. How to effectively eliminate the problems in the water supply and drainage e...Peoples life is closely related to the building, but the drainage engineering problems in the construction process has become a key problem. How to effectively eliminate the problems in the water supply and drainage engineering is very important. Because of this, the construction of water supply and drainage projects ensure the construction quality, to be in strict accordance with the norms to the construction, to avoid unnecessary problems. Building water supply and drainage engineering design as the focus of the whole project construction design, should be based on water supply engineering, drainage engineering and indoor fire engineering, strengthen the rationalization design of water supply and drainage pipeline, form a specific design scheme, so as to guide the construction.展开更多
文摘The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. One coefficient of Meij was also improved to more directly show element enrichment in combustion products. These elements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2 Cr has properties of both group 1 and 3 In addition, the smaller diameter of fly ash, the more relative enrichment of trace elements(except Mn). The fly ash showed different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not always improve the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Trace elements should be classified in accordance with factors.
文摘Peoples life is closely related to the building, but the drainage engineering problems in the construction process has become a key problem. How to effectively eliminate the problems in the water supply and drainage engineering is very important. Because of this, the construction of water supply and drainage projects ensure the construction quality, to be in strict accordance with the norms to the construction, to avoid unnecessary problems. Building water supply and drainage engineering design as the focus of the whole project construction design, should be based on water supply engineering, drainage engineering and indoor fire engineering, strengthen the rationalization design of water supply and drainage pipeline, form a specific design scheme, so as to guide the construction.
