气体灭火系统受干扰的原因及防范措施

介绍气体灭火系统受外界干扰导致误喷放的情况,从探测器、控制器和线路方面,探讨形成干扰的主要类型和原因,结合实际工程中的应用情况,有针对性地提出防范措施.     

景婺黄高速公路蛟岭隧道施工中瓦斯处治方法研究

通过对江西省景婺黄高速公路蛟岭隧道施工中所遇到的瓦斯情况进行分析,并总结其经验教训从设计完善、瓦斯防治、结构措施等角度,提出一些处治方法和建议,经实践证明是行之有效的,可供同类工程借鉴与参考。     

基于柔性管线的Flex-Lay铺管船的发展

Flex-Lay铺管船是柔性管线铺设平台,通过分析全球Flex-Lay铺管船发展现状,Flex-Lay铺管船正向专业化和多功能化方向发展,为我国Flex-Lay铺管船发展提供借鉴。     

Effect of Explosion in a Gas Pipeline Compartment of a Utility Tunnel on Neighboring Metro Tunnels北大核心CSCD

In this paper the numerical simulation analysis of the effect of explosion in the gas pipeline compartment of a utility tunnel on neighboring metro tunnels was conducted using the software AUTODYN. The results show that the TNT equivalent in a fireproof partition with length of 200 m is 41.6 kg when the gas concentration in the gas pipeline compartment reaches 10%; the blast wave has much effect on the crown and arch waist of the round metro tunnel and it’s necessary to take some protective measures in both areas; when the surrounding soil is sand, the utili- ty tunnel is above the round metro tunnel and their alignments are in the same direction, the greater the vertical spacing between the utility tunnel and the metro tunnel, the smaller the effect of the blast wave on the metro tunnel; when the vertical spacing is 7.2 m, the maximum dynamic tensile stress is 1.86 MPa (including the static stress value of 1 MPa in the tunnel segment) and it is slightly smaller than the designed tensile strength of metro tunnel (about 1.89 MPa). The maximum vibration velocity and the maximum displacement meet the structural stability require- ments, so it is suggested the vertical spacing between the utility tunnel and metro tunnel shall not be less than 7.2 m. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Cost-effectiveness of reductions in greenhouse gas emissions from High-Speed Rail and urban transportation projects in California

A rising trend in state and federal transportation finance is to invest capital dollars into projects which reduce greenhouse gas (GHG) emissions. However, a key metric for comparing projects, the cost-effectiveness of GHG emissions reductions, is highly dependent on the cost-benefit methodology employed in the analysis. Our analysis comparing California High-Speed Rail and three urban transportation projects shows how four different accounting framings bring wide variations in cost per metric tonne of GHG emissions reduced. In our analysis, life-cycle GHG emissions are joined with full cost accounting to better understand the benefits of cap-and-trade investments. Considering only public subsidy for capital, none of the projects appear to be a cost-effective means to reduce GHG emissions (i.e., relative to the current price of GHG emissions in California’s cap-and-trade program at $12.21 per tonne). However, after adjusting for the change in private costs users incur when switching from the counterfactual mode (automobile or aircraft) to the mode enabled by the project, all investments appear to reduce GHG emissions at a net savings to the public. Policy and decision-makers who consider only the capital cost of new transportation projects can be expected to incorrectly assess alternatives and indirect benefits (i.e., how travelers adapt to the new mass transit alternative) should be included in decision-making processes.     

液化天然气(LNG)汽车日常检查方法及维护技术综述

天然气是一种优质的替代燃料,具有污染小、安全系数高、运行费用低等优点。天然气已经成为城市公共交通领域应用最为成功和广泛的车辆替代燃料技术,为推动交通运输行业的节能减排做出了显著的贡献。液化天然气汽车,作为天然气汽车的一种类型,与传统汽柴油车相比,液化天然气汽车安装了包括液化天然气气瓶、气管路及各种控制阀门和仪表在内的专用装置,在对液化天然气汽车进行日常检查时需要针对液化天然气汽车的专用装置进行重点检查。本文则针对液化天然气汽车的特点,对液化天然气汽车的正确使用方法、日常检查方法及维护技术要求、以及相关注意事项三个方面进行了解读,为指导液化天然气汽车进行日常检查与定期维护提供了技术参考。     

天然气车辆推广应用政策措施研究

天然气车辆因其能源结构调整效益和节能减排效益,在道路运输行业应用日趋广泛。但同时,其后期应用过程中的问题也随之显现,为引导道路运输企业更加科学合理的应用天然气汽车,本文通过对当前天然气车辆应用现状的分析,总结应用过程中的问题,对天然气车辆开展成本效益分析,最终提出适合天然气车辆推广应用的政策建议。     

输气管道置换优化研究

置换是输气管道投产试运过程中的重要工艺环节,是复杂的扩散、对流过程。文中介绍了输气管道投产前用氮气置换空气的几种方法,阐述了它们的工作原理与实施步骤,对比分析了它们的优缺点,优选了置换方式,并采用Fluent流体模拟软件建立了输气管道氮气置换数学模型,进行了三维稳态和非稳态数值计算,研究了置换过程中混气段长度随管径、管长、流速变化规律,将理论推导、数值计算和现场数据进行了对比,验证了理论结果的正确性,为现场施工提供了科学依据。     

机械复合管在海底管道中的应用

原油、湿气含有CO2或H2S是造成海底管道内腐蚀失效的主要原因之一。机械复合管作为一种新型管材,可以有效解决CO2或H2S造成的内腐蚀问题,在国际上得到了广泛应用,但其在国内油气田开发海底管道中,尚无应用先例。文中介绍了机械复合管的制造原理、设计制造规范、用作海底管道的技术要求、海上安装技术特点以及应用前景。文中研究了机械复合管在海底管道中应用对设计制造和安装技术的要求,以推动其在国内油气田开发海底管道中的应用。     

埋地管道防腐层破损点检测技术综合应用研究

对防腐层完整性检测尤其是对防腐层破损点的精确定位,及对检出大、中面积破损点开挖修补,是确保土壤跟管道的有效绝缘、提高阴极保护效果的关键。文中分析了常用埋地钢质管道防腐层破损点检测技术特点,结合现场检测实践,综合应用多种技术,能有效检测埋地钢质管道防腐层破损点。根据测量数据可以判断破损点大小以及是否开挖修理,在管道安全运行及检测的经济性之间寻找结合点。