精馏塔压力热旁路控制系统中热旁路气体流量的计算

精馏塔压力热旁路控制系统已被广泛用于石油化工装置中。热旁路气体的流量是热旁路控制系统的一个重要参数,是保证该系统正常操作的关键因素。本文介绍了两种用于计算热旁路气体流量的经验方法,即回流罐内气、液介质混合后全部变为饱和液体的方法和维持回流罐内气、液界面"液膜"温度恒定的方法。以某MTBE装置催化蒸馏塔热旁路控制系统为具体实例,分别计算出热旁路气体的流量并与工艺包数据作比较。结果表明用前一种方法计算的数据与工艺包数据相贴近。实际设计过程中热旁路气体流量可按塔顶气体总量的15%~25%取值。     

不同压力下内锥流量传感器压力损失系数的数值模拟研究

利用数值模拟软件,通过改变管道内气体的压力,对内锥流量传感器的压力损失系数进行模拟研究。对大量模拟实验数据进行处理后可以发现,内锥流量传感器的压力损失系数会随着管道内气体压力的变化而发生改变。当管道内气体压力在0.1-0.3 MPa的范围内变化时,压力损失系数会随着气体压力的增大而减小。     

自动复叠制冷系统压力特性

针对自复叠制冷系统开机初期排气压力和排气温度过高的问题,以三级自动复叠制冷装置为研究对象,设计了一种压力调节和控制系统,主要包括缓冲器、膨胀容器、压力控制阀和管路等。缓冲器具有缓和高压气体对设备的冲击和降压稳压作用;膨胀容器具有收纳和贮存制冷工质的作用。缓冲器中引出一个旁通支路,通过电磁阀和膨胀容器后实现高低压旁通;两个相分离器上部各引出一个气体支路,通过手动球阀和流量计并联旁通到膨胀容器,对压缩机的排气压力和排气温度进行有效控制和调节。通过实验研究,具有旁通的冷柜系统启动初期降温速度加快,能够快速冷却制冷工质。通过压力控制阀对系统的旁通量进行调节,从而控制系统的压力和温度在合理的范围内,避免压力控制装置强制停机。     

气体浮子流量计测量误差的实验研究

在水流量标准装置上刻度气体浮子流量计后,分别在水流量标准装置和气体流量标准装置上研究了其测量误差。实验研究发现,在水装置上检定的气体浮子流量计测量空气流量时测量值大于真实值,其原因为:检定介质的动力粘度大于被测介质的动力粘度。故为了保证浮子流量计的精度等级,在水装置上检定气体浮子流量计时,必须考虑流体粘度的影响,在刻度换算公式中引入粘性系数k。     

标准表法气体流量标准装置的研制

在分析标准表法气体流量标准装置基本工作原理的基础上对装置结构进行了设计,重点对装置管道压力损失进行了分析计算,对风机选型进行了分析,对装置整体不确定度分配进行了计算,并确定了标准表、温度传感器和压力传感器的选型方案。给出了对装置进行流量稳定性测试及仪表检定实验的结果。对标准表法流量标准装置的普及应用及对流量计研究水平的整体提高有重要意义。     

蒸汽流量测量的重度自动补正(续)

Ⅲ、气体流量、过热蒸汽流量测量的温度、压力自动补正一、气体流量测量的温度、压力自动补正根据节流装置测量原理,其气体体积流量方程为:     

大庆炼化公司乙苯装置苯塔技术改造

介绍了中国石油大庆炼化公司100 kt/a干气制乙苯装置苯塔(T-401)的两项技术改造:苯塔压力控制系统改造和苯塔内件改造。改造后苯塔压力控制系统自控率有所提高,苯塔操作也随之平稳,能耗下降6.01 kg标油/t乙苯;全塔压降降低、温度分布有了明显改善、产品质量合格率有所提高、回流量减小,能耗降低5.83 kg标油/t乙苯。     

浅谈气体流量测量中的温度及压力补偿

根据理想气体定律,由几种常用流量计的流量方程,求证了对气体体积流量的温度及压力补偿的计算公式及其相对误差的计算公式.并通过两个工程实例,按照可能出现的几种极限工况,计算分析了对气体体积流量测量进行温度及压力补偿与否的误差及其分布情况,提出了对气体体积流量测量进行温度及压力补偿的实施建议.     

气力输送系统实验装置及其测定

介绍了德国进口气力输送实验装置及数据采集分析系统，给出采用该实验装置可进行的有关气力输送方面的实验研究工作及成果，如物料运动状态、悬浮速度、压力损失及实验装置的主要技术参数等，对实验结果进行了分析，并给出该系统管内气体流量换算公式。     

变压吸附制氢装置解吸气的综合利用

中石化安庆分公司真空变压吸附氢提纯装置解吸气热值低、压力低、气量大，通过采用新型低压低热值火嘴，改造原有燃料气压力控制系统，安全地将VPSA装置富含氢气的解吸气引入加热炉作燃料，避免了大量气体放火炬，经济效益显著。为同类型装置探索出了一条简单易行、经济合理的解吸气利用途径。     

段塞流的流量瞬变特性试验研究

An investigation of the characteristics of flowrate transients within slug flow was conducted in a largescale outdoor testing facility.The test section consisted of a 378m long,7.62cm diameter stainless steel pipe. Air and water were used as the test fluids.The response to a change of flowrate o either phase or two phases was measured using a series of pressure transducers and differential pressure transducers.An increase or decrease in gas flowrate caused a pressure overshoot above the value at new steady state or led to a pressure undershoot to form a temporary stratified flow.Pressure waves existed in the pipeline,spreading from the entrance to the exit.The magnitude of pressure overshoot in “up-gas”transient or of pressure undershoot and period of the temporary stratified flow in “Down-gas” transient are related to the change of gas flowrate and the distance away from the entrance.In contrast,the change in liquid flowrate was accommodated by smooth transitions between the corresponding steady states,and only one obvious change was found in the slug frequency.According to experimental results,the pressure overshoot,pressure undershoot and the pressure wave propagation were analyzed,and the phenomena were explained reasonably.Some correlations for the calculation of the pressure overshoot and undershoot were proposed.     

Flow Characteristics and Shannon Entropy Analysis of Dense‐Phase Pneumatic Conveying of Pulverized Coal with Variable Moisture Content at High Pressure

Experiments consisting of dense‐phase pneumatic conveying of pulverized coal using nitrogen were carried out in an experimental test facility, with a conveying pressure of up to 4 MPa. The influences of the conveying differential pressure, the coal moisture content, the gas volume flow rate and the superficial velocity, on the solid‐gas ratios, were investigated. The Shannon entropy analysis of the pressure fluctuation time series was developed to reveal the flow characteristics. By investigation of the distribution of the Shannon entropy at different conditions, the flow stability and the evolutional tendency of Shannon entropy, in different regimes and regime transition processes, were revealed, and the relationship between Shannon entropy and the flow regime was also established. The results indicate that the solid‐gas ratio and the Shannon entropy rise with increases in conveying differential pressure. The solid‐gas ratio and the Shannon entropy reveal preferable correlation with the superficial gas velocity. Shannon entropy is different for different flow regimes, and can be used to identify the flow regimes. Both the mass flow rate and the Shannon entropy, decrease with increases in moisture content. Shannon entropy analysis is a feasible approach to researching the characteristics of the flow regime, the flow stability and the flow regime transitions in dense‐phase pneumatic conveying systems, at high pressure.     

Effects of pressure and temperature on flow regimes in gas—Solid fluidization systems

The effects of operating temperature and pressure on the flow regimes of gas—solids fluidization are predicted based on the recently published flow regime diagram of Bi and Grace (1995b). The predictions are consistent with the evidence available in the literature. At constant superficial gas velocity, increasing system pressure and decreasing system temperature shift the behaviour toward higher velocity flow regimes. The opposite trends are realized if, instead, the gas mass flowrate is held constant.     

上升管中严重段塞流的流型和压力波动特性

During the exploitation of offshore oil and gas, it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system. The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m. It is found that severe slugging can be divided into three severe slugging regimes: regime I at low gas and liquid flow rates with large pressure fluctuation, intermittent flow of liquid and gas in the riser, and apparent cutoff of liquid phase, regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff, regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow. The results indicate that severe slugging still occurs when the declination angle of pipeline is 0˚, and there are mainly two kinds of regimes: regime I and regime II. As the angle increases, the formation ranges of regime I and regime III increase slightly while that of regime II is not affected. With the increase of gas superficial velocity and liquid superficial velocity, the pressure fluctuation at the bottom of riser increases initially and then decreases. The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.     

气液两相流流量变化瞬态特性

在气液混输管线中常发生流量变化引发的瞬态过程,在大型多相流实验环道上进行了流量变化的瞬态实验.气量突增产生压力过增量,它的产生与流型有关：分层流的过增量是由于气体的惯性;在气团流和段塞流下则是由于气体压缩性和液体惯性的联合作用.气量突降时,膨胀波沿程传播.气量变化的瞬态过程可能出现对应准稳态变化没有出现的流型.与气量突变相比,液量突变引起的压力和流型变化较平缓,瞬态效应小.流量变化后产生沿线传播的压力波和空隙波,二者与流型相关,决定瞬态过程的发展.压力变化的传播速度在气量变化时等于声速,在液量变化时等于空隙波波速.     

粉煤在流化料仓中的下料特性

在自行设计的有机玻璃流化料仓系统上对粉煤下料过程及其特性进行了实验研究。研究发现，在筒仓段与料斗段连接处上方存在一个临界面。在临界面以上的筒仓段，粉煤以柱塞流形式下料，在临界面以下，粉煤以不定向螺旋运动下料。研究结果表明，料斗下部的流化气对下料稳定性和下料流率有重要影响，存在最佳流化气位置区间和最佳流化气表观气速范围，当流化气补气位置太低，在补气位置附近易形成气压平衡拱。研究还表明，增加料仓压力能提高粉煤下料流率，改善下料稳定性，减弱流化气补气位置及气速对下料的影响，阻止气压平衡拱生成。     

Measurment of gas-liquid two-phase slug flow with a Venturi meter based on blind source separation☆

We propose a novel flow measurement method for gas–liquid two-phase slug flow by using the blind source sep-aration technique. The flow measurement model is established based on the fluctuation characteristics of differ-ential pressure (DP) signals measured from a Venturi meter. It is demonstrated that DP signals of two-phase flow are a linear mixture of DP signals of single phase fluids. The measurement model is a combination of throttle re-lationship and blind source separation model. In addition, we estimate the mixture matrix using the independent component analysis (ICA) technique. The mixture matrix could be described using the variances of two DP sig-nals acquired from two Venturi meters. The validity of the proposed model was tested in the gas–liquid two-phase flow loop facility. Experimental results showed that for most slug flow the relative error is within 10%. We also find that the mixture matrix is beneficial to investigate the flow mechanism of gas–liquid two-phase flow.     

干式气柜在炼油厂回收低压瓦斯气中的应用

气柜是储存、回收炼油厂低压瓦斯和调节瓦斯管网压力的重要设施,也是炼油厂重要的环保设施,在炼油厂低压瓦斯的平衡中起着重要的作用。吉林石化公司干式气柜设计容积为30 000 m3,是在吉林石化公司炼油厂现有瓦斯系统的基础上,通过新建的干式气柜,对瓦斯气的不均衡性起到缓冲作用,以最大能力回收炼油厂的低压瓦斯气,减少环境污染。干式气柜投运以来,运行良好,创造了较好的经济效益。     

Flow Regime Identification in a Slurry Bubble Column from Gas Holdup and Pressure Fluctuations Analysis

Analysis of gas holdups and pressure fluctuations are conducted in a slurry bubble column to study changes in flow regimes and comparisons are made with solid‐free bubble column. The pressure fluctuations are measured by fast response pressure transducers mounted on the column wall in the distributor and bulk regions. Air, tap water and 35 micron glass beads are used as the gas, liquid and solid phases respectively. Statistical analysis of pressure fluctuation data combined with gas holdup analysis provided information about flow regime transition and interesting insights into bubble size distributions and changes in flow structure.     

Transient analysis of gas flow in a straight pipe

In the present work, numerical simulation has been done to analyze transients in gas flow and pressure in a horizontal straight pipe. For a single gas pipeline, eight representative cases corresponding to different causes of transient behaviour are simulated to predict unsteady state flow and the evolution of pressure profiles. The numerical results show that depending upon the pipe dimensions and operating variables such as pressure and gas flow rate, transient effects in the pipeline may last for a long time and/or over significant length of pipe. The simulations predict an initial surge in gas flow rate greater than the final steady‐state value if the pressure drop across the pipe is increased. Similarly, initial flow rate may decrease below the final steady‐state value if the pressure drop is decreased. In case of complete closure of a valve, oscillations in both pressure and mass flow rate are observed, which gradually decay and the steady state conditions of no flow are ultimately achieved. The present results are compared with a published work from the literature. A reasonably good agreement is found between these two predictions. The present study is of practical significance in safe design and operation of a gas delivery system.