Emissions of SO2, NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass

This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.     

Management of an Agroecosystem

Agroecosystems (AESs) are autotrophic ecosystems managed by man. The goal of the management is to obtain the maximum possible amount of high-quality agricultural products while preserving agricultural resources, primarily the soils and biodiversity. The main components of the management of AES structures and functions, including primary and secondary biological production, the ratio between the energy flows in the plant–man and plant–livestock–man food chains, the efficiency of energy transfer in the plant–livestock link, and conservation of agricultural resources, are considered.     

煤矿矸石山自燃爆炸机理初步分析与研究

就煤矿矸石山自燃机理、爆炸机理进行了分析研究,给出了煤矿矸石山自燃爆炸发生必要条件和外部影响因素.     

三峡水库“水华”成因初探

2004年3月、5月、7月、8月、10月和2005年5月对长江干流29个站点进行了5次调查。2004年3月（旱季）在三峡库区坝前（秭归）发现藻类“水华”，藻类密度达2.73×106 cells/L，优势种类为拟多甲藻。2004年8月（雨季）和2005年4月（旱季）沿香溪河下游及河口区以及香溪河口到三峡大坝干流江段进行了2次6个断面分层调查，两次调查中在香溪河下游以及香溪河口区发现了严重的藻类“水华”，藻类密度高达1.87×107 cells/L 和1.67×107 cells/L，优势种分别为蓝隐藻（1.84×107 cells/L）和美丽星杆藻 (1.34×107 cells/L)。相关分析结果表明：三峡库区干流藻类数量和生物量与水库的出水流量有着显著的负相关(Spearman，r=-1.000, r=-0.900, p<0.05)，而与可溶性营养盐（NO3 N, PO4 P, SiO3 Si）的浓度无显著的相关性；在2004年7~8月（雨季）香溪河下游及河口区浮游植物生物量与主要营养盐（NO3 N, PO4 P,SiO3 Si）的浓度呈显著负相关（Spearman,p<0.01, p<0.05,p<0.01, n=21）；在2005年4月（旱季）该河段藻类密度与主要营养盐（NO3 N N,SiO3 Si）呈显著负相关 (Spearman, p<0.05，p<0.01,n=28)，但与PO4 P无显著的相关性。香溪河口到秭归的坝前库区河段藻类数量与主要营养盐（NO3 N, PO4 P,SiO3 Si）没有显著相关性(Spearman, │r│<0.2, n=20)。然而香溪河下游及河口区主要营养盐（NO3 N, PO4 P, SiO3 Si）浓度却低于长江干流。可以推断三峡库区蓄水后干流和支流发生“水华”的最主要原因是筑坝后库区内水动力条件的改变而非营养盐浓度较高。随着三峡工程的全面完工，库区内水体滞留时间的进一步延长，三峡库区水体富营养化趋势将会进一步加剧。     

地浸采铀技术与工艺

地浸采铀是世界上十分先进的采矿技术，其基本原理是对可地浸砂岩型铀矿按一定网度布置工艺钻孔，从注液注孔入地浸液，使地浸液与铀进行充分反应，经铀液孔提出地表，在地表工厂进行萃取铀的过程，地浸法分为酸法和碱法两种，地浸采铀能使低品位砂岩型铀矿成为有工业价值的矿床，由于对环境污染小，已被世界大多数国家广泛采用。但是并非所有的砂岩铀矿都能地浸，只有符合地浸地质-水文评价指标的砂岩铀矿才能地浸。地浸工艺包括钻孔的布置、浸液的配制、地下水的复原和环境保护等方面。我国的地浸采铀于20世纪70年代开始探索，90年代中期开展了大规模的地浸砂岩铀找矿与开采工作，并取得了突破性进展，新疆512矿床是就是利用地浸技术评价与开采的我国第一座大型地浸铀矿山。     

微生物絮凝剂

综述了微生物絮凝剂的产生和培养条件 ,同时讨论了微生物絮凝剂的絮凝反应条件 ,反应机理和在废水处理中的应用 ,提供了今后的研究方向。     

英语教学中的文化导入

语言和文化是密不可分的,在外语教学中要达到语言与文化并重的目的,就要充分重视文化导入的问题.本篇文章详细阐述了文化导入问题在英语教学中的重要性以及外语教学中文化导入的内容及方法.     

试论民族精神的社会功能

本文认为,民族精神的社会功能主要体现在三个方面。首先,民族精神在促进政治变革、维护政治稳定、促进祖国统一、抵御外来侵略、战胜自然灾害、维护民族的国际政治地位等方面具有十分重要的政治功能;其次,民族精神在促进经济发展、保障经济安全、对经济发展进行价值引导等方面,具有日益重要的经济功能;最后,民族精神在保证民族文化的传承、促进民族文化的创新和维护民族文化的安全和独立等方面,具有日益重要的文化功能。     

催化柴油加氢改质研究

采用一种双功能催化剂对硫，氮，芳烃含量较高的劣质催化裂化柴油（PCC－LCO）进行加氢改质，可以大幅度地提高柴油的十六烷值，并且能够保主柴油馏分的收率大于95v%.     

Phenotype-dependent arrival time and its consequences in a migratory bird

Arrival times for migratory animals can be viewed as the result of an optimization process of costs and benefits of early arrival, and when the cost and benefit functions of early arrival depend on phenotypic quality, this will result in phenotype-dependent optimal arrival times. This hypothesis was tested for males of the migratory and sexually size-dimorphic barn swallow Hirundo rustica. The major cost of early arrival is poor environmental conditions which resulted in mortality of short-tailed early-arriving males in one year. The major benefits of early arrival are higher mating success, enhanced reproductive success, improved recruitment rates for offspring, and enhanced quality of the mate acquired. Annual variation in male arrival date is related to weather conditions at the breeding grounds, but also to some extent to weather conditions in the African winter quarters. Individual variation in arrival time can be explained by phenotype-dependent cost and benefit functions of early arrival. Male barn swallows with long tail ornaments arrived earlier than short-tailed males. The costs of early arrival should be particularly high under poor environmental conditions and lead to a stronger negative relationship between arrival date and phenotypic quality in years with poor environmental conditions. This prediction was confirmed by a stronger negative relationship between male tail length and date of arrival in years when arrival was relatively late because of poor weather. A female preference for early-arriving males may result in acquisition of good genes for optimal migratory behaviour, if migratory direction and extent have a genetic basis as shown in a number of different bird species.