基于SVM的天然气管道泄漏次声波检测技术研究

为了有效的对天然气管道泄漏进行及时识别,根据管道泄漏信号特征,本文采用了次声波检测技术进行长距离输气管道泄漏检测。结合支持向量机(SVM)人工智能识别理论,提出了基于次声波-SVM的管道泄漏智能识别方法。应用该智能识别方法对实际天然气管道泄漏进行检测实验研究,同时对影响SVM识别准确度的三类核函数进行了对比分析。实验结果表明:基于次声波-SVM(RBF核函数)的检测模型识别准确率最高,且该方法可以有效满足长输管道的泄漏检测。     

管道泄漏检测系统中次声波信号传播规律研究

由于输油输气管道的运行环境不同、输送介质不同,从而造成了每条管道的声波信号完全不同,管道泄漏声发射信号既携带系统结构中的某些特征信息(泄漏孔大小和位置等),同时又有很大的随机性和不确定性。次声波泄漏检测技术是对管壁状况检测的声发射检测方法和基于现代信号处理的检漏方法二者结合,从而进行管道泄漏检测和泄漏点的定位。文章中把次声波传感器接受泄漏次声信号的过程比拟为"听"的动作,来研究在油气管道泄漏检测系统中次声波信号传播的规律。     

高压天然气管道泄漏及事故危害规律研究

天然气长输管道泄漏扩散的基本理论,全面分析了影响天然气泄漏扩散的因素;建立了天然气长输管道泄漏模型,对不同影响因素下天然气泄漏的压力场、速度场、浓度场以及危险区域进行了模拟分析,阐述了不同工况下天然气长输管道泄漏的规律;通过模拟对比分析了不同泄漏孔径、不同泄漏压力对泄漏区域的影响;模拟分析了气体中含硫化氢和泄漏区域有建筑物时的泄漏规律。     

架空天然气管道泄漏扩散过程特性分析

在天然气管道集输过程中,由于管道老化、腐蚀等因素引起的泄漏事故时有发生,会引起穿孔泄漏后的天然气扩散,可能会引发火灾、中毒或爆炸。因此,进行架空天然气管道泄漏扩散过程的影响因素模拟研究及分析,对天然气管道输送安全运营和保障人生财产安全意义重大。文章建立了架空天然气管道在迎风坡和背风坡处发生泄漏扩散过程的物理模型,并利用CFD软件对架空天然气管道泄漏后的甲烷气体扩散过程进行了数值模拟。结果表明：泄漏的甲烷气体扩散范围和速度非常大,在泄漏时间300S时泄漏距离已经达到40m,并在40m处形成高浓度的甲烷气团;泄漏点在背风坡时,山坡附近形成高浓度甲烷气团。     

天然气长输管道泄漏工况分析

天然气长输管道具有压力高、流量大的特点,当管道发生泄漏或断裂时,天然气迅速扩散形成危险区域,当空气中天然气浓度达到爆炸极限,可能发生爆炸严重威胁生命安全。针对此现状,对目前天然气长输管道发展现状进行对比分析,多角度调研泄漏发生的原因,模拟分析空隙泄漏带来的影响,并提出不同工况下应对天然气长输管线泄漏的方法,为降低管道泄漏危害提供借鉴。     

泄漏报警技术在油气田地面管道中的应用

通过对5种常用的管道泄漏报警技术原理和优缺点的对比分析,选择较优的次声波法和分布式光纤法应用于西部某油田管道的泄漏检测报警中,现场测试结果表明:次声波法可检测到的最小泄漏孔径为3mm,响应时间不大于1min,定位精度小于50m;分布式光纤法的响应时间不大于10s,定位精度小于20m。     

埋地天然气管道泄漏激光检测影响分析

激光技术是天然气管道泄漏检测的重要手段,而泄漏扩散过程对其检测过程存在一定影响。通过建立埋地天然气管道泄漏扩散模型,模拟得到了泄漏天然气扩散特性,计算了天然气扩散光谱检测值,分析了不同检测高度、不同泄漏口大小以及不同风速对天然气扩散光谱特性的影响。研究表明:泄漏口越大,测得的光谱检测曲线越低,降低幅度在距泄漏口40 m内最为明显;有风速影响时,光谱检测曲线最低点均向下风向偏移,在距泄漏口6 m左右时光谱检测值最小。研究结果可为合理有效地进行激光检测提供参考。     

泄漏速度对激光检测天然气管道泄漏影响分析

天然气管道泄漏产生的危害极大,激光技术是检测管道泄漏的重要手段,但泄漏扩散过程对其检测存在一定的影响。建立了架空天然气管道泄漏扩散模型,数值分析了不同泄漏速度下管道泄漏天然气扩散过程,然后探讨了不同探测高度下其对激光检测的影响。研究结果表明:在同一泄漏速度下,随着探测高度的增加,激光检测信号强度越来越弱;在同一探测高度下,中速泄漏时激光检测信号强度稍强于高度泄漏,明显弱于低速泄漏。     

高含硫天然气管道泄漏数值模拟

高含硫天然气管道经长期的内外腐蚀,经常发生泄漏事故.为了减少和降低天然气管道泄漏事故对人的危害,对甲烷及硫化氢的扩散规律进行研究日趋重要.利用计算流体力学的方法,采用仿真软件对高含硫天然气架空及埋地管道穿孔泄漏后的甲烷、硫化氢气体的扩散进行了数值模拟.架空管道泄漏初期为体积分数等值线呈对称分布的射流,泄漏至60s后无爆...     

城市天然气管网泄漏事故发生规律研究

为了有效控制城市天然气管网泄漏事故的发生,保障天然气管网的安全运行,以某燃气公司2009~2014年的天然气管网泄漏事故数据为基础,采用Excel软件对不同条件下包括不同管道直径、管道材质、管道压力、泄漏起因、月份和时间段等事故进行数据分析,得到不同因素对天然气管网泄漏事故影响规律。数据分析结果表明,最容易发生燃气泄漏事故的条件是管径32 mm、镀锌管、低压、接口泄漏和白天,预防与控制天然气事故的发生重点需要从低压民用镀锌管道进行,特别加大白天管道接口的巡检力度。     

Fast gas combustion in systems with hydraulic resistance

Various aspects of the sonic velocity regime, one of the steady-state regimes of filtration combustion of gases, is analyzed. The conditions and region of existence of the regime, the velocity and structural characteristics of the combustion wave, the gas ignition and combustion mechanisms, conditions for the stabilization of the wave velocity, and regime transitions are considered. A characteristic feature of the regime is the presence of a pressure wave in the zone of turbulent flame due to the choking of channels and narrowings. The main factors determining the nature and properties of the sonic velocity regime are the hydraulic resistance, piezo diffusion, the energetics of the mixture, the compressibility and turbulence of the gas, and the reactivity of the mixture at high pressures and temperatures. The sonic velocity regime is a unique and intriguing combustion regime which is promising for applications.     

Study of horizontal sonic gas jets in gas–solid fluidized beds

Existing jet penetration correlations have all been developed for sub‐sonic gas jets and have been found to perform poorly when employed in sonic and supersonic regimes. In the present study, triboelectric probes were used to measure both the penetration depth and expansion angle of sonic gas jets. Experiments were conducted using nozzles of different size and geometry, different particle types, different injection gases, and different fluidization velocities. All these data were used to develop a new, general correlation to predict the penetration depth of sonic gas jets. The effects of these variables on jet expansion angle were also studied.     

掺混纳米微粉的聚碳硅烷熔融纺丝工艺研究

运用功率超声将纳米Ｎｉ粉均匀分散到聚碳硅烷（ＰＣＳ）中，通过熔融纺丝制备出了直径约１５～３５μｍ的有机纤维。研究了超声过程对纳米微粉分散状态的影响及掺混型ＰＣＳ熔融纺丝的工艺条件。     

泡沫塑料成型过程中超声波振动对气泡成核的影响

综述了在泡沫塑料成型过程中超声波振动对气泡成核行为的影响，分别用经典成核理论和分子聚团理论解释了超声波振动作用下的气泡成核现象，提出可以从能量的角度进一步深入研究超声波振动对气泡成核的影响。     

基于负压波和音波的成品油管道泄漏定位综合分析

油气输送管道关乎国家能源安全,近年来随着石油工业的发展,敷设管线大幅增多。由于腐蚀和人为破坏等问题,管道泄漏事故时有发生,不仅对环境污染严重,而且也威胁沿线群众的生命财产安全。基于负压波、音波、质量或体积等单因素的管道泄漏监测系统在国内得到了广泛应用,但是影响管道泄漏监测系统有效性的因素有很多,这时候用单因素进行管道泄漏定位会出现较大的偏差。本文提出的基于负压波和音波的成品油管道泄漏综合定位方法,可以有效地降低有害因素对监测系统的影响,对管道泄漏点进行准确的定位,为管道运行和维护人员提供科学依据。     

超音速脱水技术应用进展

综合评述了超音速脱水技术的基本原理、过程技术特点、设备构造、应用实例及其优缺点。并对超音速脱水技术的研究前景进行了展望。     

Ultrasonic and thermal properties of γ-irradiated low-density polyethylene

The ultrasonic pulse-echo technique and differential thermal analysis were utilized to characterize and to monitor the effect of γ-irradiation on the sonic modulus and the heat effect of low-density polyethylene. The sonic wave velocity, sonic modulus, and specific gravity exhibit a minimum for samples irradiated at 10 Mrad. A minimum in the heat capacity was observed at 1 Mrad. The estimated relative change of the activation energy of ordering exhibits a minimum at 100 Mrad. Below 10 Mrad, the perturbation and the loss of the crystalline phase override the effect of radiation cross-linking. From 10 to 100 Mrad, the effect of cross-linking as well as that of crystallinity are prevailing. Oxidative degradation is dominating above 100 Mrad. © 1993 John Wiley & Sons, Inc.     

AN EXPLORATORY STUDY OF A COMBINED SONIC AGGLOMERATION AND CROSSFLOW FILTRATION SYSTEM FOR HOT GAS CLEANUP

The Institute or Gas Technology has investigated a combined sonic agglomeration/crossflow filtration system to remove particles smaller than 10 microns from high-temperature, high-pressure gas streams. Sonic energy induces agglomeration so that particles can be removed in a continuously operating cross-flow filler element. Cold-model and preliminary high-temperature, high-pressure results are promising.

The objective of this investigation was to explore the potential effectiveness of sonic agglomeration, crossflow filtration, and a combination of these techniques to remove particles from high-temperature, high-pressure (HTHP) gas streams. The technique of sonic agglomeration has been known since the 1930's, and crossflow filtration has been used successfully in liquid filtration. This investigation is unique in that these two techniques were combined. Sonic energy was used to agglomerate particles to sizes large enough to be separated from the gas stream in a crossflow filter. The crossflow filter has advantages over conventional filters as a paniculate agglomerate removal system because it (1) operates continuously, (2) does not subject the fragile agglomerates to the high stress typical of inertial capture devices, and (3) can control the buildup of a filter cake when properly combined with a sonic agglomerator.

This investigation was supported by the Gas Research Institute and the Institute of Gas Technology Internal Research and Development Fund.

In this preliminary study, we found that—

• A 2-micron porosity filter must be used to achieve 98% paniculate removal from 95% of a dust-laden stream. (In the crossflow operating mode, 5% of the stream bypasses the filter.)

• When sonic agglomeration is combined with crossflow filtration, the same removal efficiency can be achieved with a 10-micron porosity filter.

• Combined sonic agglomeration/crossflow filtration removed particulates smaller than 10 microns in experiments at 265° C and 7000 kPa.

• The pressure drop across a 10-micron filter is about one-half that of a 2-micron filter, which could reduce the energy requirements for filtration.

This method of particulate removal should be applicable to many different coal reactor effluent streams, especially because it can operate at elevated temperatures and avoid gas cooling, liquid condensation, and subsequent liquid-solids separation. Preliminary estimates show that the power requirements of a combined sonic agglomerator/crossflow filter are lower than those of a crossflow filter alone, and that they are lower than or comparable with other particulate removal techniques. Additional tests are needed to establish the degree to which these benefits can be realized.     

AN EXPLORATORY STUDY OF A COMBINED SONIC AGGLOMERATION AND CROSSFLOW FILTRATION SYSTEM FOR HOT GAS CLEANUP

The Institute or Gas Technology has investigated a combined sonic agglomeration/crossflow filtration system to remove particles smaller than 10 microns from high-temperature, high-pressure gas streams. Sonic energy induces agglomeration so that particles can be removed in a continuously operating cross-flow filler element. Cold-model and preliminary high-temperature, high-pressure results are promising.

The objective of this investigation was to explore the potential effectiveness of sonic agglomeration, crossflow filtration, and a combination of these techniques to remove particles from high-temperature, high-pressure (HTHP) gas streams. The technique of sonic agglomeration has been known since the 1930's, and crossflow filtration has been used successfully in liquid filtration. This investigation is unique in that these two techniques were combined. Sonic energy was used to agglomerate particles to sizes large enough to be separated from the gas stream in a crossflow filter. The crossflow filter has advantages over conventional filters as a paniculate agglomerate removal system because it (1) operates continuously, (2) does not subject the fragile agglomerates to the high stress typical of inertial capture devices, and (3) can control the buildup of a filter cake when properly combined with a sonic agglomerator.

This investigation was supported by the Gas Research Institute and the Institute of Gas Technology Internal Research and Development Fund.

In this preliminary study, we found that—

? A 2-micron porosity filter must be used to achieve 98% paniculate removal from 95% of a dust-laden stream. (In the crossflow operating mode, 5% of the stream bypasses the filter.)

? When sonic agglomeration is combined with crossflow filtration, the same removal efficiency can be achieved with a 10-micron porosity filter.

? Combined sonic agglomeration/crossflow filtration removed particulates smaller than 10 microns in experiments at 265° C and 7000 kPa.

? The pressure drop across a 10-micron filter is about one-half that of a 2-micron filter, which could reduce the energy requirements for filtration.

This method of particulate removal should be applicable to many different coal reactor effluent streams, especially because it can operate at elevated temperatures and avoid gas cooling, liquid condensation, and subsequent liquid-solids separation. Preliminary estimates show that the power requirements of a combined sonic agglomerator/crossflow filter are lower than those of a crossflow filter alone, and that they are lower than or comparable with other particulate removal techniques. Additional tests are needed to establish the degree to which these benefits can be realized.     

几何尺寸对音波振荡器射流流动特征的影响

音波振荡器内射流流动特征主要由振荡器几何尺寸决定,因此对几何尺寸对流动特征的影响进行了实验和数值模拟研究,得到：（1）射流振荡周期和控制管长呈正比,与声波在管中传播周期近似相等;（2）控制管过长、过宽或过窄,均不能产生稳定振荡射流,音波振荡器正常工作时的控制管长范围随控制通道变窄而缩小;（3）劈距或位差过小,射流均不能附壁,且两者之间存在耦合关系,劈距减小,则产生振荡射流的最小位差增大。