Removal characteristics of sulfuric acid aerosols from coal-fired power plants

With increasing attention on sulfuric acid emission, investigations on the removal characteristics of sulfuric acid aerosols by the limestone gypsum wet flue gas desulfurization (WFGD) system and the wet electrostatic precipitator (WESP) were carried out in two coal-fired power plants, and the effects of the WFGD scrubber type and the flue gas characteristics were discussed. The results showed that it was necessary to install the WESP device after desulfurization, as the WFGD system was inefficient to remove sulfuric acid aerosols from the flue gas. The removal efficiency of sulfuric acid aerosols in the WFGD system with double scrubbers ranged from 50% to 65%, which was higher than that with a single scrubber, ranging from 30% to 40%. Furthermore, the removal efficiency of WESP on the sulfuric acid aerosols was from 47.9% to 52.4%. With increased concentrations of SO₃ and particles in the flue gas, the removal efficiencies of the WFGD and the WESP on the sulfuric acid aerosols were increased.

Implications: Investigations on removal of sulfuric acid aerosols by the WFGD and the WESP in the power plants were aimed at the control of sulfuric acid emission. The results showed that the improvement of the WFGD system was beneficial for the reduction of sulfuric acid emission, while the WESP system was essential to control the final sulfuric acid aerosol concentration.     

Off-design performance analysis of a transcritical CO2 Rankine cycle with LNG as cold source

The transcritical CO₂ Rankine cycle with liquefied natural gas (LNG) as cold source is a promising power system to utilize mid- and low-temperature heat source. Most previous works focused on thermodynamic and thermoeconomic analysis or optimization for the system. In this article, an off-design performance analysis for the system is conducted. An off-design mathematical model for the system is established to examine the variation of system performance with the variations of heat source mass flow rate and temperature. A modified sliding pressure regulation control strategy, which regulates turbine inlet pressure to keep the temperature difference between heat source temperature and turbine inlet temperature constant, is applied to control the system when off-design conditions happen. The results show that when the mass flow rate or the temperature of heat source is less or lower than that of design condition, both the net power output of system and the system exergy efficiency decrease, whereas when they are more or higher than the values of design condition, the net power output of system increases but the system exergy efficiency still decreases. In addition, both CO₂ turbine and NG turbine could almost keep the designed efficiency values under the applied control strategy.     

Estimating Root Zone Soil Moisture at Continental Scale Using Neural Networks

This study investigates the feasibility of artificial neural networks (ANNs) to retrieve root zone soil moisture (RZSM) at the depths of 20 cm (SM20) and 50 cm (SM50) at a continental scale, using surface information. To train the ANNs to capture interactions between land surface and various climatic patterns, data of 557 stations over the continental United States were collected. A sensitivity analysis revealed that the ANNs were able to identify input variables that directly affect the water and energy balance in root zone. The data important for RZSM retrieval in a large area included soil texture, surface soil moisture, and the cumulative values of air temperature, surface soil temperature, rainfall, and snowfall. The results showed that the ANNs had high skill in retrieving SM20 with a correlation coefficient above 0.7 in most cases, but were less effective at estimating SM50. The comparison of the ANNs showed that using soil texture data improved the model performance, especially for the estimation of SM50. It was demonstrated that the ANNs had high flexibility for applications in different climatic regions. The method was used to generate RZSM in North America using Soil Moisture and Ocean Salinity (SMOS) soil moisture data, and achieved a spatial soil moisture pattern comparable to that of Global Land Data Assimilation System Noah model with comparable performance to the SMOS surface soil moisture retrievals. The models can be efficient alternatives to assimilate remote sensing soil moisture data for shallow RZSM retrieval.     

Occurrence and profiles of polybrominated diphenyl ethers (PBDEs) in riverine sediments of Shanghai: a combinative study with human serum from the locals

Herein, we studied the occurrence and profiles of thirteen PBDE congeners in 30 river sediment samples from Shanghai, China. The concentrations of Σ₁₃PBDEs ranged from 110 to 13,071 pg g ^?1 dw, with an average value of 2,841 pg g ^?1 dw. BDE-209 was the predominant congener accounting for more than 65 % of total PBDEs, demonstrating that the major source of PBDEs in sediment samples was associated with the prevalent use of technical deca-BDE products. Moreover, low brominated BDEs in sediments also came from the degradation of higher brominated BDEs. In addition, taking into consideration of dietary exposure, PBDEs in serum samples collected from the locals were also detected with range of 419–26,744 pg g^?1 (average 5,561 pg g ^?1), which suggested a relatively low burden of PBDEs contamination to human body compared with the condition in other place. And in serum, low brominated compounds constituted the majority of total PBDE congeners.     

Interactions of operating parameters on the production of waste polypropylene pyrolysis oil: neural fuzzy model and genetic algorithm optimization

Journal of Material Cycles and Waste Management - This study aims to maximize the waste polypropylene (WPP) pyrolysis oil yield by regulating the operating parameters. The interactions of operating...     

对美军装备采购合同管理的分析与借鉴

装备采购合同管理是装备采购管理的重要组成部分,是军方依法执行合同、实现合同权利的主要手段。对美军装备合同管理进行分析,进而提出若干有益于我军装备采购合同管理的借鉴意见。     

战场损伤评估程序研究

由于现行战场损伤评估程序相对简单,与实际战场评估活动需求有一定的差距。根据美军飞机和车辆战场损伤评估程序,对战场损伤评估程序进行了详细分析和改进。改进后,战场损伤评估程序分为3个主要组成部分,即战场损伤评估前应明确的问题、系统级评估、关键件级评估。战场损伤评估前应明确的问题包括损伤装备和战术要求两个方面。系统级评估主要包括损伤定位和确定关键件。关键件级评估包括损伤定位、确定抢修方法和提交评估报告3方面。最后,以某火炮为例进行了实例分析。     

微小卫星动力学环境试验及其数据处理

以上海微小卫星工程中心与复旦大学力学与工程科学系共同合作的微小卫星动力学试验研究项目作为背景,主要通过某真实型号微小卫星的振动环境试验和结构模态试验来介绍微小卫星环境试验技术和试验响应数据的处理方法。     

双循环两相生物处理工艺(BICT)除磷中试试验

一种新型的生物脱氮除磷工艺——双循环两相生物脱氮除磷工艺,它是在序批式活性污泥法基础上增设独立的生物膜反应器,实现微生物的分相培养,对提高脱氮除磷效率、增强系统运行的稳定性和可靠性提供了很大的潜力。通过对城市污水的试验,结果表明,在适宜的负荷和运行条件下TP去除率可达90%,出水TP浓度可控制在1·0mg/L以下。     

Distribution and bioaccumulation of organochlorine pesticides (OCPs) in food web of Nansi Lake,China

The concentration of 12 organochlorine pesticides (OCPs) were measured in water, sediment, aquatic plant, and animal (shrimp and fish) of Nansi Lake by gas chromatography equipped with an electron capture detector. The total OCPs concentrations were 65.31–100.31 ng L^?1 in water, 2.9–6.91 ng g^?1 dry weight (dw) in sediments, 1.29–6.42 ng g^?1 dw in aquatic plants and 7.57–17.22 ng g^?1 dw in animals. The OCPs composition profiles showed that heptachlor compounds was also the predominant OCPs contaminants in addition to hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Nansi Lake. According to the source of HCHs and DDTs in sediment samples, there was no new input and the HCHs pollution mainly came from the use of Lindane in Nansi Lake. Bioaccumulation of OCPs in aquatic biota indicated that DDTs and heptachlor compounds had a strong accumulation, followed by HCHs and drins. The accumulation abilities of fish for OCPs were higher than those of plants and shrimps. The OCPs biota-sediment accumulation factor values of Channa argus was the highest in fish samples, followed by Carassius auratus, and Cyprinus caspio. Risk assessment of sediment showed that heptachlor epoxide had a higher occurrence possibility of adverse ecological effects to benthic species. Based on the calculation of acceptable daily intake and hazard ratio, HCHs in fish and shrimps from Nansi Lake had a lifetime cancer risk of greater than one per million. The risk assessment of water, sediment, and fish indicated the water environment of Nansi Lake is at a safe level at present.