RESUMO
A 660 MW unit of an ultra-low emission coal-fired power plant in the Beijing-Tianjin-Hebei area was chosen for this study. The particulate matter was sampled with a Dekati low-pressure impactor (DPLI) at the inlet and outlet of flue gas cleaning devices including selective catalytic reduction (SCR), low-low temperature economizer (LLTe), electrostatic precipitator (ESP), wet flue gas desulfurization (WFGD), and wet electrostatic precipitator (WESP). A filter sampling system was also used at the inlet and outlet of the WFGD and WESP. The removal efficiencies of PM1, PM1-2.5, and PM2.5-10 from different flue gas cleaning devices were obtained after ultra-low emission modification. The results show that SCR increases the mass concentration of fine particulates and PM1 by 52.11%. The LLTe improves the removal efficiency of the ESP, especially for particles with a range of 0.1-1 µm. The high-efficiency WFGD removes both SO2 and particulates, but it increases PM1. The mass concentration of PM1 increases by 59.41% and the water-soluble Mg2+, Cl-, and SO42- in PM10 increases. The WESP has a high removal efficiency with respect to PM1, PM1-2.5, and PM2.5-10 and can further reduce the dust concentration. Based on an ultra-low emission reform, the final PM10 emission of this 660 MW unit is 2.04 mg·m-3.
RESUMO
The diversity of 166 cotton cultivars(cult.) including 159 upland(G. hirsutum L) and 7 island(G. barbadense L) ones planted mainly in China since 1949 was explored by RAPD, genetic distance(GD) and cluster analysis. The correlation coefficients between Nei's GD of RAPDs and two groups of phenotype data's Euclidean distances (UD) were 0.6445(n = 1770) and 0.7078 (n = 7140), which indicated that RAPD could be used to explore genetic diversity among cotton cultivars in China. The genetic basis of cotton cultivars in China was studied by comparison among different cotton species, different cultivar types, different history periods, different growing regions and different sources. The results showed as follows:within cotton cultivars planted in China, the genetic basis of island cotton cultivars was narrower than that in upland ones; the genetic basis of cultivars released in China since 1949 was narrower than that of introduced ones from outside of China; the genetic basis of hybrids was narrower than that of conventional cultivars(Conv. Cult.); the genetic basis of upland cultivars after 1980 was narrower than that in 1970's; the genetic basis of cultivars in Changjiang cotton region was narrower than that of Huanghuai cotton region, northwestward cotton region was the narrowest. From which some strategies for breeding, especially for the methods of widening the genetic basis of China cotton cultivars, could be understood and withdrawn.
