Application of CFD model in an LPG tank explosion accident

In this research, a 3D tank farm model of a petrochemical plant was built in order to analyze an LPG tank explosion accident. Furthermore, the Computational Fluid Dynamic (CFD) algorithm was also applied to reconstruct the scenario of the accident. With its 3D dynamic abilities, the CFD simulation results can be used to facilitate the understanding of the spatial and transient distribution of different hazardous physical variables, which cannot be observed from the traditional methods.After the maximum physical variables of overpressure, pressure-impulse, and thermal radiation temperature were calculated, the results were adopted to estimate the corresponding 3D individual risk value. With the aid of the CFD simulation and the analysis method of maximum physical variable, the researchers can use the simulation results to scrutinize the possible causes and consequences of a chemical accident.     

吹吸罩在大型酸洗槽上的应用研究

大型酸洗槽的酸雾收集处理是很多企业污染治理的难题,不仅造成环境污染,而且直接威胁操作人员的健康,为解决此问题,我们利用吹风射流作用将有害物质输送到排风罩口附近并被排走的原理,通过研究吹吸气流的合理设计和计算方法,研制和设计了应用于大型酸洗槽的酸雾收集处理吹吸罩装置,实现了在减少抽风量,降低动力消耗基础上,有效提高酸雾收集效率,并且便于操作,应用前景广阔。     

Carbon balance of an intensively grazed temperate pasture in two climatically contrasting years

Grazed grasslands occupy 26% of the earth's ice free land surface and are therefore an important component of the global C balance. In New Zealand, pastoral agriculture is the dominant land use and recent research has shown that soils under intensive dairy pastures have lost large amounts of carbon (∼1000 kg C ha⁻¹ y⁻¹) during the past few decades. The objective of this research was to determine the net ecosystem carbon balance (NECB) of an intensively grazed dairy pasture in New Zealand. Net ecosystem CO₂ exchange (NEE) was measured using an eddy covariance (EC) system from 1 January 2008 to 31 December 2009. Other C imports (feed) and exports (milk, methane, leaching, and harvested biomass) were calculated from farm production data and literature values. During 2008 there was a one in 100 year drought during summer/autumn, which was followed by a very wet winter. There were no prolonged periods of above or below average rainfall or soil moisture in 2009, but temperatures were consistently lower than 2008. The severe summer/autumn drought during 2008 caused a loss of CO₂ to the atmosphere, but annual NEE remained negative (a CO₂ sink, −1610 ± 500 kg C ha⁻¹), because CO₂ lost during the drought was regained during the winter and spring. The site was also a net CO₂ sink during 2009 despite the colder than usual conditions (−2290 ± 500 kg C ha⁻¹). Including C imports and exports in addition to CO₂ exchange revealed that the site was a C sink in both years, with a NECB of 590 ± 560 kg C ha⁻¹ in 2008, and 900 ± 560 kg C ha⁻¹ in 2009. The C sequestration found in this study is in agreement with most other Northern Hemisphere EC studies of grazed pastures on mineral soils, but is not consistent with the large C losses reported for soils under dairy pastures throughout New Zealand. In the current study (like many other EC studies) the influence of climatic conditions and management practices on the annual C balance was only semi-quantitatively assessed. An extended period of EC measurements combined with modelling is required to more accurately quantify the effect of different climatic conditions on the annual C balance, and the influence of different management practices needs to be quantified using specifically designed studies (such as paired EC towers), so that practices which minimise C losses and maximise C sequestration can be identified.     

提高液化气罐区事故预防能力

膨胀压力和静密封泄漏是液化气罐区两大不安全因素,介绍了消除膨胀压力和控制静密封泄漏、稀释泄漏浓度、抢险堵漏的方法和注意事项。     

大型常压储罐在用检验技术与策略

介绍了钢制立式焊接常压储罐主要的损伤机理、主要检测标准和各种无损检测方法在储罐检验中的应用特点以及基于风险检验的理念,提出了储罐在用检验的技术方法和策略。     

USE OF SOIL AND WATER PROTECTION PRACTICES AMONG FARMERS IN THE NORTH CENTRAL REGION OF THE UNITED STATES1

ABSTRACT: Data were collected in the fall of 1998 and the winter of 1999 from 1,011 land owner‐operators within three watersheds in the North Central Region of the United States to assess adoption of soil and water protection practices. Farm owner‐operators were asked to indicate how frequently they used 18 different agricultural production practices. Many farmers within the three watersheds had adopted conservation protection practices. However, they also employed production practices that could negate many of the environmental benefits associated with conservation practices in use. Comparison of adoption behaviors used in the three watersheds revealed significant differences among the study groups. Respondents in the Iowa and Ohio watersheds reported greater use of conservation production systems than did farmers in Minnesota. However, there were no significant differences between Ohio and Iowa farmers in terms of use of conservation production practices. This was surprising, since farmers in the Ohio watershed had received massive amounts of public and private investments to motivate them to adopt and to continue using conservation production systems. These findings bring into serious question the use of traditional voluntary conservation programs such as those employed in the Ohio watershed. Study findings suggest that new policy approaches should be considered. It is argued that “whole farm planning” should be a significant component of new agricultural conservation policy.     

Connecting environmental management and farm household livelihoods: The Rural Environment Protection Scheme in Ireland

This paper presents the relationship between an environmental protection scheme, established in Ireland in 1994 under EU Regulation No. 2078/92, and the livelihoods of Irish farm households. It explores this relationship within the framework of the new policy environment for EU agriculture and rural areas as set out in Agenda 2000. At the centre of this new policy environment is the European model for agriculture, embodying the concept of multifunctionality, which recognizes the pivotal position of an evolving agricultural sector in enhancing the viability of rural areas through broadening the assets of farm families. Research undertaken with farm households in the west of Ireland indicates a positive relationship between the Rural Environmental Protection Scheme and the economic and natural assets upon which they build their livelihoods. The case of a small-scale dairy farm household is presented, showing clearly the positive impact of the scheme, while also highlighting the vulnerability of these improvements. A major challenge facing policy-makers is the extent to which acceptable levels of income and an enhanced natural environment on such farms can be sustained. The position of advisory and research institutions in strengthening human capacities on farms is highlighted and their enhanced role is suggested in order to give meaning to multifunctional and sustainable agriculture within the context of rural area viability. Copyright © 2001 John Wiley & Sons, Ltd.     

区域农地市场发育对农户水土保持行为的影响及其空间差异--基于生态脆弱区江西省兴国县、上饶县、余江县村域农户调查的分析

分析农户水土保持决策过程、建立农户水土保持决策的两阶段概念模型,从理论上分析了土地市场对农户水土保持的影响.运用在江西省兴国县、上饶县和余江县的样本村农户调查资料,通过建立土地流转与农户水土保持相互关系模型,运用Heckman的两阶段法对模型参数进行了估计.运用模型估计结果,分析土地流转对农户水土保持决策的影响并且对其区域差异进行了探讨.结果表明:从全部样本来看,农户是否意识到水土流失问题的存在以及家庭土地税费负担量对农户是否采取水土保持决策有显著影响;在兴国县,土地流入面积和费用2个因素对水土保持决策有显著影响;在余江县土地流入面积和费用也有影响显著,并且土地流入面积对农户水土保持投入的影响更强,而且土地流出面积在余江也有显著影响;上饶县,土地流出面积有显著影响.在全部样本、兴国县以及余江县,土地流出收益对农户水土保持决策的影响都不显著.最后,就进一步推进区域水土流失治理促进土地持续利用提出了相关建议.     

钢丝绳产业区重金属对土壤－农产品的复合污染及生态风险评价?

选取钢丝绳行业比较发达的某乡镇为研究区域,对其地区周边土壤及农产品的污染状况进行了野外调查和实验分析研究。结果表明：（1）土壤中铅、锌的含量均有不同程度的污染。（2）土壤中重金属含量与废水灌溉方式有关。（3）废水灌溉的农产品均有不同程度的污染。（4）重金属主要富集在农产品的根部,果实中富集的量很少。     

CSTR+UASB技术在养殖场沼气工程的应用

养殖场产生的粪污是有价值的可回收资源,采用CSTR和二次发酵技术相结合的工艺技术,对高TS的有机废水的处理具有较好的效果。经过处理,可实现废物的资源化利用,沼气燃烧的热量可用于对消化器的加温,保证设备在高寒地区的正常运行。沼渣、沼液可创造经济效益。该技术对高寒地区的沼气处理工程的应用具有推广意义,既创造了生态效率,又实现了经济效益。