基于深冷技术的液化天然气蒸发气提氦流程优化分析

针对中国宁夏银川某一提氦工厂液化天然气蒸发气(LNG-BOG)提氦液化流程,采用Aspen Hysys构建BOG提氦气系统和氦气液化系统的流程模型,首先分析了BOG提氦气流程中关键参数对能耗设备的影响情况。之后采用遗传算法,以系统单位能耗为目标函数,分别对BOG提氦气系统和氦气液化系统中关键能耗参数进行优化。同时采用■分析方法,分析优化前后氦气液化系统的■效率以及■损失情况。结果表明,BOG提氦气系统和氦气液化系统经优化后系统单位能耗分别为8.351 5 kWh/Nm³和0.751 9 kWh/Nm³,相比优化前分别下降7.09%和14.71%,且氦气液化系统■效率较优化前提高了18.54%,■损失下降12.79%,换热器换热总量约上升2.54%。因此整个系统在优化后单位能耗有所降低,系统运行经济性得到提高。     

大型氦气压缩机技术特点和发展趋势

氦气压缩机是大型低温系统的核心设备之一,压缩机的可靠性和经济性直接决定了低温系统的可靠性和效率。通过回顾大型低温系统氦气压缩机技术的发展历史,总结了喷油式氦气螺杆压缩机的技术特点、关键技术和国产化进程。分析了喷油式氦气螺杆压缩机在低温工程上的技术缺陷及带来的问题。对比分析了氦气压缩机无油化措施的优缺点和适用范围。提出了新型高效离心式氦气压缩机技术,介绍了离心式氦气压缩机技术中的关键点及其解决措施。期望高效可靠的氦气压缩机技术为相关大科学装置的稳定运行提供有力的技术保障。     

BEPC-Ⅱ低温系统的氦气净化技术

氦气净化技术是国家大科学工程北京正负电子对撞机重大改造(BEPC-Ⅱ)中低温系统的关键技术之一.在充分调研国内外大型低温系统氦气净化技术的基础上,结合自身情况,创造性提出氦气储罐内部处理及真空置换方案,一次性充入氦气,将储罐内氦气不纯度控制在40 vpm之内,同时辅之以80 K外置低温吸附器对氦气储罐内以及冷箱和超导设备端的氦气进行净化.高效而又经济的解决了BEPC-Ⅱ低温系统中的氦气纯度问题,成功地进行了制冷机的验收测试和超导设备的调试及运行.     

第十六讲 真空系统的操作与维护

<正>(上接2010年第4期112页)6.5.2.4制冷单元的故障对系统的影响如果制冷机系统的故障不是在气体压缩单元、连接管道和真空系统,则问题一定在制冷单元。与制冷单元有关的故障有:1)机械零件的磨损;2)密封元件的老化;3)工作氦气的泄漏;4)供气气流所引起的污染;5)超负荷运行。     

空调检漏氦气提纯循环利用系统的研究

针对空调行业氦气检漏过程存在氦气浪费大的现象研究出一种氦气提纯循环利用系统,该系统利用膜分离技术将空调检漏系统排放的废氦气进行回收提纯,并循环供给低压罐以供给空调检漏系统使用,从而有效减少生产过程中对于氦气的消耗量。     

氦气放空管道和氦气回收系统的连接结构

对ＭＲＩ１．０Ｔ核磁共振成象设备配套的氦气放空管道的结构、回收系统的低压回气管道与设备连接结构和氦气回收系统的改进做了介绍。在第一次用液氦预冷磁体的输液过程中，ＭＲＩ设备蒸发出的大量氦气全部被氦气回收系统回收，总共回收氦气６４６．４ｍ￣３。     

林德集团支持臭氧层环境研究项目

2010年2月10日,林德集团气体部宣布了一项供气协议——向德国于利希研究中心协办的一个国际科学联盟提供液氦、液氮以及其他特种气体（包括氦气、一氧化碳和医疗级氧气）。气体将由林德瑞典公司AGA供应,用于一项重要的大气研究课题,以评估气候变化对臭氧层的影响。     

大型氦低温系统中的杂质净化

EAST是一个全超导的托卡马克核聚变实验装置,磁体采用超临界氦迫流冷却.磁体在降温过程中对氦气的纯度有很高的要求,净化系统是整个低温系统的重要环节之一,以防各种杂质气体在低温下凝结固化威胁低温系统的稳定可靠运行.理论分析了氦气纯化的基本原理及固定床吸附器的吸附机理,对低温纯化器的运行进行了阐述,并介绍了杂质成分检测系统,以对净化效果进行评估,实验得知氦气净化系统能满足低温系统氦气高纯度的要求.     

几种实用的氦气回收系统

本文比较系统介绍了氦气回收系统的工作原理、技术要求、连接结构、使用情况以及几种实用的氦气回收系统。     

核电站废气处理系统氦气检漏试验方法研究

密封性能测试是核电厂系统调试中经常遇到的问题。氦气检漏作为密封性能测试方法的一种,它的检漏灵敏度远远超过了压降法、煤油渗漏和氨泄漏等试验方法。本文对比常见的排水集气法和压降法,结合秦山二期扩建工程废气处理系统调试,详细介绍了含氢废气子系统密封性能试验方法的选定及氦气检漏漏试验的原理和试验过程。氦气检漏试验结果表明,秦山二期扩建工程废气处理系统密封性能试验获得了成功,密封性达到了设计要求。     

中性束注入器真空系统设计

中性束注入器（NBI）真空系统的性能对束传输效率以及整个束线内相关部件的使用寿命与使用安全影响极大。本文结合中性束注入器对真空系统的要求，对真空室的结构选择及气源分布进行了分析并对各气源的气量大小进行了计算。为NBI设计了一套以4．2K液氦低温冷凝泵为真空主抽泵并配以涡轮分子泵机组的抽气系统，采用此真空系统的NBI系统具有良好的真空性能。     

流动现场监测用微型PDHID气相色谱仪的研制及其应用

应用进口VICI公司的脉冲放电氦离子化检测器(PDHID)、网络化电控系统、四阀三柱气路系统和结构小型化设计,研制成功一种可方便移动到现场监测的高灵敏度微型气相色谱仪,可应用于有关高纯气体生产现场和大型变压器现场进行现场在线监测。     

Cryogenic helium gas circulation system for advanced characterization of superconducting cables and other devices

A versatile cryogenic test bed, based on circulating cryogenic helium gas, has been designed, fabricated, and installed at the Florida State University Center for Advanced Power Systems (FSU-CAPS). The test bed is being used to understand the benefits of integrating the cryogenic systems of multiple superconducting power devices. The helium circulation system operates with four sets of cryocooler and heat exchanger combinations. The maximum operating pressure of the system is 2.1 MPa. The efficacy of helium circulation systems in cooling superconducting power devices is evaluated using a 30-m-long simulated superconducting cable in a flexible cryostat. Experiments were conducted at various mass flow rates and a variety of heat load profiles. A 1-D thermal model was developed to understand the effect of the gas flow parameters on the thermal gradients along the cable. Experimental results are in close agreement with the results from the thermal model.     

A self-circulation helium liquefaction system with five 4 K G-M cryocoolers

A self-circulation helium liquefaction system (SCHLS) with five 4 K G-M cryocoolers is developed to supply liquid helium (LHe) for SECRAL (a superconducting ECR ion source used in Lanzhou city, China). LHe is vaporized in SECRAL and warmed up to room temperature. SCHLS will re-liquefy the helium gas at a rate of 83.2 L/day under normal atmosphere pressure. With SCHLS, SECRAL system can run online without any interruption of refilling LHe.     

基于通信光缆的光纤油气管线预警系统

提出了一种以光纤分布式扰动传感器为核心,通过随油气管线一同敷设的标准通信光缆为传感介质的新型光纤管线预警系统.该系统利用激光干涉的原理对扰动信号进行实时探测,从而实现对挖掘、偷盗和第三方破坏等事件导致的扰动的实时监测和定位,从而达到管线安全预警的功能.该预警系统成功研制后分别在津唐输油处石油管线和杭州至嘉兴天然气管线进行了多次外场测试,该系统能在长达60 km的管线上实现250 m的定位精度,具有很好的定位稳定性.其测试结果表明:与传统油气管线监测手段相比,该系统具有无需外场供电、本质安全、灵敏度高,监测距离长、可定位以及可预警监测等技术优势,是未来油气管线监测的发展趋势.     

Development of a Superconducting Magnet System with Zero Liquid Helium Boil-off

A homogeneous magnetic field superconducting magnet with a cold bore of 250 mm and a central field of 4.3 T has been designed, manufactured, and tested with zero liquid helium boil-off. As a result of magnetic field homogeneity considerations, the magnet is composed of three coaxial coils: one main coil and two compensation coils. All coils are connected in series and can be charged with a single power supply. The magnetic field homogeneity is about ±3.0 % from ?200 mm to 200 mm in axial direction with 86 mm in diameter. The magnet can be operated in persistent mode with a superconducting switch. A two-stage GM cryocooler with a capacity of 1.5 W at 4.2 K was used to cool the superconducting magnet. The cryocooler prevents the liquid helium from boiling off and leads to zero helium loss during static operation. The magnet can be operated in liquid helium circumstance by cooling the gas helium with the cryocooler without additional supply of liquid helium. Under this condition, the magnet is successfully operated up to 4 T without quench. The magnet system can be generating 0.25 L/h liquid helium with the cryocooler by supplying the gas helium without loading the magnet. In this paper, the magnet design, manufacture, mechanical behavior analysis, and the performance test results of the magnet are presented.     

An efficient helium circulation system with small GM cryocoolers

We developed a helium circulating system that re-liquefies all the evaporating helium gas and consumes far less power than conventional systems, because warm helium gas at about 40 K collected high above the surface of the liquid helium in the Dewar is used to keep the Dewar cold, and because cold helium gas just above the liquid helium surface is collected and re-liquefied while still cold. A special transfer tube with multi-concentric pipes was developed to make the system operate efficiently. The system can produce up to 35.5 l/D of liquid helium from the evaporated helium using two 1.5 W@4.2 K GM cryocoolers.     

Helium detection in gas mixtures by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) has been evaluated as a tool for monitoring trace levels of helium in gas mixtures consisting mostly of hydrogen. Calibration data for helium in hydrogen was investigated at different helium concentration levels. At high concentrations of helium (>7.25%), the LIBS signal is quenched due to Penning ionization. The hydrogen alpha line (656.28 nm) was observed to broaden as the concentration of helium impurities in the hydrogen gas mixture increased. The helium line at 587.56 nm was selected as the analyte line for helium impurity detection. The effects of laser energy, the delay time between the laser pulse and data acquisition, and the gas pressure on the LIBS signal of helium were investigated to determine the optimum conditions for helium detection. The LIBS signal from the helium line at 587.56 nm shows good linear correlation with helium concentration for He concentrations below 1%. Thus, LIBS can be reliably used to detect the low levels of helium. The limit of detection for helium was found to be 78 ppm.     

烟气在线监测系统及思考

固定污染源排放的烟气会对环境造成污染,对其进行科学监测至关重要。本文介绍了现有的烟气在线监测系统,包括空气质量自动监测系统、烟气排放连续监测系统、差分光学吸收光谱法在线连续监测系统、物联网下无线传感器网络技术在线监测系统等,介绍了每个系统的组成、技术特点、监测方法、实际应用和发展方向,并从量值溯源和远程校准两个方面对烟气在线监测系统与计量系统的关系进行了阐述。     

基于PLC和组态王的真空检漏回收装置监控

为实现电冰箱整机、空调器及蒸发器和冷凝器等部件在流水线上焊接工序后进行快速检漏和氦气的循环利用,研发了真空检漏回收装置监控系统.该系统采用上下位机控制模式,上位机采用工控机+组态软件,下位机采用OMRON中型CQMIH,充分发挥各自优势,实现了真空检漏回收装置的监控.实际运行表明,系统最小可检漏率达到1×10-3Pa·m3/s,氦气回收率不低于97％.