船舶SO_x排放控制技术研究

应对IMO Tier III SOx排放法规,目前有三种技术方案,即使用低硫燃油、液化天然气以及废气洗涤技术。基于船舶动力装置和不同技术方案的具体特点,分别从成本、对发动机和环境的影响、应用可行性以及未来前景等方面,对上述三种硫排放控制技术进行了分析。分析表明:相比之下,废气洗涤方案是最可行和最经济的硫排放控制技术。     

容错性控制在LNG扩建项目中的应用

文章主要介绍容错性控制在上海五号沟LNG扩建项目中的应用和实现。整套控制系统包括新老站区DCS系统的集成和容错方法。     

Numerical modelling and flow visualization of mixing of stratified layers and rollover in LNG

A numerical model has been developed to study the mixing of two initially stratified layers which are subjected to a uniform lateral heat flux. An important distinction is made between the free surface and the liquid/liquid interface with regard to the different flow characteristics of the two layers. In the upper layer where warm liquid is cooled at the evaporating surface, the convective circulation is featured by a strong downward core flow; in contrast, the fluid flow in the lower layer is mainly confined to the wall boundary and is much weaker. Flow visualization experiments show that mixing of two stratified layers generally involves two stages in sequence: migration of the interface and rapid mixing between the remaining liquids. The interface movement is due to entrainment mixing at the interface. When the two layers approach density equalization, the interface becomes increasingly unstable and the core flow in the upper layer is able to break into the lower layer. The base to side heat flux ratio appears to be a major factor in determining the mode and intensity of the subsequent mixing at a rollover incident.     

Thermodynamic analysis of an LNG fuelled combined cycle power plant with waste heat recovery and utilization system

This paper has proposed an improved liquefied natural gas (LNG) fuelled combined cycle power plant with a waste heat recovery and utilization system. The proposed combined cycle, which provides power outputs and thermal energy, consists of the gas/steam combined cycle, the subsystem utilizing the latent heat of spent steam from the steam turbine to vaporize LNG, the subsystem that recovers both the sensible heat and the latent heat of water vapour in the exhaust gas from the heat recovery steam generator (HRSG) by installing a condensing heat exchanger, and the HRSG waste heat utilization subsystem. The conventional combined cycle and the proposed combined cycle are modelled, considering mass, energy and exergy balances for every component and both energy and exergy analyses are conducted. Parametric analyses are performed for the proposed combined cycle to evaluate the effects of several factors, such as the gas turbine inlet temperature (TIT), the condenser pressure, the pinch point temperature difference of the condensing heat exchanger and the fuel gas heating temperature on the performance of the proposed combined cycle through simulation calculations. The results show that the net electrical efficiency and the exergy efficiency of the proposed combined cycle can be increased by 1.6 and 2.84% than those of the conventional combined cycle, respectively. The heat recovery per kg of flue gas is equal to 86.27 kJ s^?1. One MW of electric power for operating sea water pumps can be saved. The net electrical efficiency and the heat recovery ratio increase as the condenser pressure decreases. The higher heat recovery from the HRSG exit flue gas is achieved at higher gas TIT and at lower pinch point temperature of the condensing heat exchanger. Copyright © 2006 John Wiley & Sons, Ltd.     

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随着对清洁能源需求量的日益增长，天然气国际贸易量正在不断加大。远隔重洋地区的天然气贸易是依靠将天然气液化后通过船运来完成的，因而LNG船就成为了完成天然气远洋贸易的关键设备。文章回顾了LNG船的发展史，介绍了LNG船的技术特点和一些配套设施，同时还阐述了我国需要建立自己的LNG船队，从而保证我国LNG进口的重要意义。     

大型LNG储罐保冷性能的研究

根据LNG储罐的结构,给出储罐热流量和静态蒸发率的计算方法。利用该方法对济南某3×104m3双金属LNG储罐热流量和静态蒸发率进行计算,分析储罐热流量的影响因素。结果表明:案例储罐的静态蒸发率为0.074 8%,静态蒸发率较小,储罐的保冷性能良好。环境温度对储罐热流量的影响较大,环境风速和充满率对储罐热流量的影响较小。     

LNG加气站工艺危害分析

采用危险源辨识、合规性核查、HAZOP分析、自控系统评价、安全仪表系统评价、安全阀设置评价、人为因素分析等方法,对6座在役LNG加气站开展首次工艺危害分析。辨识出高、中、低风险隐患共计106项,主要体现在工艺系统设计不合理、自控与安全仪表系统功能设计不完善、安全阀设置不合理、操作与运行管理不规范、安全间距不足等方面。综合考虑隐患的风险等级与整改难易程度,制定了风险管控措施。建议对建站较早的在役LNG加气站尽快开展首次工艺危害分析,对新建、改建、扩建LNG加气站,应在设计阶段开展工艺危害分析,及时发现并整改安全隐患,确保工艺本质安全.     

LNG冷能用于催化重整装置的研究

以某炼油厂2.3 Mt/a催化重整装置为研究对象,利用HYSYS软件对现有催化重整工艺进行了模拟。针对原装置存在流程复杂、电能消耗大等缺点,考虑通过将LNG冷能用于催化重整装置以实现对原流程的改进,在对塔参数进行优化的基础上,利用夹点技术对改进流程进行了换热网络优化,使得公用工程用量最小。最后,对LNG参与的换热过程进行火用分析及能级分析,以保证温位匹配的合理性。改进后的流程省去了压缩再接触部分,电负荷可降低了11.027 MW,氢气分离压力由2.65 MPa降低为0.34 MPa,氢气摩尔分数由94%提高到98%,回收能量18.967 MW,减小了冷热公用工程用量。通过对LNG冷能利用进行各换热装置和整体换热流程的火用分析和能级分析后对其使用效果进行评价,表明LNG冷能利用合理。     

俄罗斯放开LNG出口前景及影响分析

与管道天然气相比,俄罗斯LNG产业的发展可谓相形见绌。受全球市场影响,俄罗斯决心大力发展LNG,2013年11月俄联邦政府批准LNG出口自由化法案。该法案的颁布将有助于LNG产业的快速发展,提高俄罗斯LNG在国际市场的份额,但同时也面临来自美国和加拿大等竞争对手的压力。俄罗斯未来的LNG出口出现较大幅度增长将会是不争的事实,将影响亚洲乃至全球LNG市场,同时对地缘政治局势也有一定的影响。     

基于LNG气化冷能的回收利用

随着我国经济的快速发展,作为绿色能源的液化天然气(LNG)得到了更多的重视和利用。大量的冷能产生于LNG气化过程中,不仅造成能源的浪费,还将会造成冷污染。与此同时LNG所携带的冷能具有重大的经济价值。文章描述了对液化天然气气化过程中所产生的冷能相关的回收及再利用。