GLCC多相流量计集成优化控制策略的研究和实践

GLCC多相流分离计量系统,经过多年的实际应用和检验,基于其高效的分离效果和紧凑的机构设计已在中海油、中石油、中石化、中东等国内外得到广泛应用,在这个系统中的控制部分,对该计量系统能否正常工作和计量,及保证精度起到决定性作用。因此本文采用专业软件对实际工况进行模拟研究,并提出了GLCC多相流量计集成优化控制策略,为多相流量计的进一步研究提供一种新选择,并提供了具体的实践经验,为多相流量计的发展提供全新的思路。     

Observer design for multiphase flow in vertical pipes with gas-lift––theory and experiments

Unstable regimes occurring for multiphase flow in vertical risers have successfully been stabilized using conventional linear control techniques. However, these control systems rely on downhole measurements which are at best unreliable, if at all available. In this paper, we design a nonlinear observer for the states of the multiphase flow that relies on topside measurements only, and apply it to estimate downhole pressure for feedback control. A key feature of the design is that it exploits the structure of the model to obtain robustness with respect to the internal flows in the system. Combining the nonlinear observer with conventional PI control of the downhole pressure, we demonstrate in laboratory experiments the potential for increasing production from gas-lift wells by stabilizing the multiphase flow.     

10% increase in oil production through a field applied APC in a Petrobras ultra-deepwater well

As an offshore oil well ages, it is common for the production system to face multiphase flow problems such as limit cycles. This phenomenon, known as slugging in the jargon of the oil industry, causes oscillations in the well’s flowrate and pressure. Its main effects are reducing production and increasing the risk of operational discontinuity due to shut down. In this paper, an advanced control process (APC) strategy is presented to deal with the slugging problem in oil wells. The strategy uses a two-layer coupled control structure: a regulatory via a PID control, and a supervisory via a model-based predictive control (MPC). The structure proposed was applied to a real ultra-deepwater well in Petrobras that was partially restricted by the choke valve to avoid the propagation of oscillatory behavior to the production system. As a result, the well has achieved a 10% oil production increase while maintaining the flow free of severe slugging, which meant an increment of about 240 barrels a day for that specific well.     

修正压力与表面张力计算的两相流 自由界面运动模拟

摘 要：在利用光滑粒子流体幼力学(SPH)方法进行多相流的模拟中,多相流在交界面处由 于密度不连续、粒子界面的压力计算出现误差,出现界面处压力振荡,界面破碎的问题。针对 上述问题,提出了新的压力梯度近似公式和改进的界面处人工斥力公式,使交界面更加清晰、 光滑、无穿透、模拟效果更好。此外,通过给出基于密度权重的色函数计算公式,对大密度比 多相流界面处的表面张力计算公式进行了改进,使得多相流交界面密度过渡更加光滑,模拟效 果更好。最后,通过溃坝、Rayleigh-Taylor 界面不稳定性,非 Boussinesq 锁定交换问题 3 个仿 真实验,得到了不同时刻界面粒子分布图、界面锋面距离等。结果验证了新的压力梯度近似公 式以及界面处人工斥力公式的合理性;通过空气中液滴形成仿真实验,得到了圆形液滴形成的 粒子变化图,结果验证了该改进的表面张力计算方法的有效性。     

化学工程中的计算流体力学

本文评述了计算流体力学在化学化工研究和开发中的重要地位,介绍了各种模拟方法研究的现状、存在的困难和一些发展中的前沿领域。与传统应用领域相比,化学工程领域主要面对的是复杂多相流体系统及流动、传递和反应相耦合的过程,基于单尺度统计平均的传统连续介质方法已很难满足对产品结构和过程工艺精确设计的要求,而多尺度方法与粒子方法的结合是一条有效的途径。它通过对复杂系统满足的稳定性条件的分析以及对复杂界面和间断性的合理描述实现跨尺度关联的模拟,从而量化介观结构与行为、建立准确的宏观模型。这种结合无论是对湍流、汽液或气固多相流等传统的难题,还是对微流动、生物流、聚合物流动、颗粒流及散料力学等前沿领域,都带来了新的可能性,也将为化学化工领域的研发工作提供更有力的手段。     

New slug control strategies, tuning rules and experimental results

The challenge of handling intermittent flow with liquid slugs followed by gas pockets in multiphase flow lines becomes more important when the number of satellite fields increases. Oil, gas and water are transported from the wells in some km long flow lines along the seabed and up through a riser to the oil rig. Slugging may cause several problems for topside processing. This paper concerns suppression of slug flow by active use of the topside choke. Process measurements such as pressure and density are used in a PID controller. Slugging has been reduced significantly with such a system in operation offshore since April 2001. This paper contains results within simplified modelling of flow dynamics. New experimental results verify the dynamic model. A control scheme in operation offshore has been tested and a new control scheme independent of subsea measurements has been developed and tested in experiments.     

高压饱和气体制备系统饱和室多变量控制研究

高压饱和气体制备系统的饱和室出口压力、流量和温度调节系统是一个相互耦合的三输入三输出系统。针对以上特点采用部分解耦控制策略,压力—流量调节子系统采用静态解耦的专家控制方式,温度调节子系统采用串级模糊PID控制方式。通过仿真试验证明这种控制策略能够获得良好的控制效果。     

多相流过程参数检测技术综述

多相流是现代流程工业及其相关科研领域内常见的控制与研究对象, 对其过程参数的检测是工业生产与科学研究中的一个研究热点问题. 本文针对工业过程中的多相流过程参数检测问题,介绍了多相流的特点及其过程参数, 并分类介绍了多相流过程参数检测方法,重点讨论了检测的难点及其未来发展趋势, 为更好地解决复杂工业过程多参数检测问题提供方法基础和借鉴.     

基于前馈-反馈控制的天然气分输站场控制及前馈控制率自适应方法

天然气分输站场控制系统直接影响天然气配输质量及系统的安全可靠运行,站控系统调节阀控制是关键。目前我国天然气分输站场调节阀采用的国内厂家配置的PLC控制系统大多采用三选一式的PID控制策略,在峰谷分输、大范围调节以及上游流量压力存在较大波动的情况下普遍存在控制稳定性欠佳、调节周期长的弊端。为了改进控制效果,本文在深入分析造成控制效果欠佳原因的基础上,提出了基于前馈-反馈控制的控制策略,并基于此前馈-反馈控制策略提出了前馈控制率自适应调整方法以适应实际过程中调节阀动态特性变化额情况。在Stoner Pipeline Simulator软件仿真对象了进行了初步验证,仿真结果表明施加了前馈控制作用后控制稳定性和调节时间有显著优化,本方法具备在现场推广应用的前景。     

基于数据迁移策略的反压问题解决方法

流计算应用中由于上下游数据流入流出速率不匹配常常导致数据缓冲区容量不足或溢出的反压(backpressure)问题,轻则导致数据丢失、重则导致系统崩溃,亟需好的解决方法或方案.不同于向上游传递压力以解决下游反压的已有方法,本文提出了一种基于数据迁移策略的反压问题解决方法,通过其他分支的轻载节点分散处理来解决反压问题.我...     

单点交通信号控制系统的优化设计

针对城市固定相序的单路口多相位交通信号进行控制,本文设计了基于车流量预测的动态调整相位最大绿灯时间的模糊控制系统。综合考虑当前相位、后续相位的交通需求度,以此决定绿灯时间分配。通过模拟交通指挥者实际进行交通控制,实时根据各相位车辆的多少进行信号的智能控制。采用遗传算法对模糊隶属度函数进行优化调整,使隶属函数的选取更为合理,随交通状况的改变自适应地调整。仿真结果表明,该方法能有效降低通行车辆在交叉口的平均等待时间,明显优于传统控制方法,并且能更有效地处理随机性较大、不确定性较强的交通流。     

An investigation of multiphase CFD modelling of a lateral sloshing tank

A near-resonant, sway-induced sloshing flow in a rectangular tank is used to compare a homogeneous and inhomogeneous multiphase approach for fluid density and viscosity in a commercial CFD code. Dimensional analysis of the relative motion between the phases suggests the application of an inhomogeneous multiphase model whereas previous published work has used the computationally cheaper homogeneous (or average property) approach. The comparison between the computational and experimental results shows that the homogeneous model tends to underestimate the experimental peak pressures by up to 50%. The inhomogeneous multiphase model gives good agreement with the experimental pressure data. Examination of the relative velocity at the fluid interface confirms that the inhomogeneous model is the appropriate model to use for the simulation of a violent sloshing flow.     

翼伞系统动力学建模与分段归航设计

翼伞回收系统具有精确、定点、无损等特点,已成为当前回收领域的一个研究热点,首先建立了含附加质量的翼伞系统的六自由度动力学模型,然后将其带入翼伞系统的动力学方程中得到了运动轨迹以及三个姿态角随不同操纵方式变化的时间曲线,对翼伞系统的基本运动特性进行了分析.其次采用分段归航策略对翼伞系统的轨迹规划进行了设计,并利用遗传算法...     

基于STAR-CCM+的高速动车组驱动齿轮箱内部流场分析

为研究齿轮箱初始注油量、齿轮旋转方向等因素对齿轮箱内部润滑油瞬态分布、压力瞬态分布和各轴承进/回油孔润滑油质量流量的影响,基于齿轮箱内部不可压缩的气液两相流,采用STAR-CCM+软件的重叠网格技术对高速动车组驱动齿轮箱内部流场进行仿真.结果 表明:当大齿轮正转时,受螺旋方向的影响,车轮侧各轴承进油量大于电机侧轴承进油量;当大齿轮反转时,各轴承进油量受螺旋方向的影响较小;随着初始注油量增加,各轴承进油孔的质量流量也增加;齿轮箱内部流场达到稳态时,内部压力总体上较为平均,仅啮合区存在局部高压区与负压区.研究结果对齿轮箱润滑流道结构设计具有指导意义.     

Model-based control of multiphase flow in subsurface oil reservoirs

An emerging method to increase the recovery of oil from subsurface reservoirs is the application of measurement and control techniques to better control the multiphase flow in the reservoir over the entire production period. In particular the use of sensors and remotely controllable valves in wells and at surface, in combination with large-scale reservoir flow models is promising. Various elements from process control may play a role in such ‘closed-loop’ reservoir management, in particular optimization, parameter estimation and model reduction techniques.     

Dynamical modelling and control of plastics extrusion processes

Alternative methods for determining plastics extrusion process models, suitable for high level control, are examined and the importance of time-series techniques for feedforward control is demonstrated. The results of extrusion process dynamic model identification experiments, carried out on a single screw extruder used for processing polyethylene, are described. Some results of exploratory control strategy simulations are included. Control of plastics melt pressure and temperature at the die is suggested as an effective indirect means of controlling die flow rate in most industrial situations.     

Leakage monitoring research and design for natural gas pipelines based on dynamic pressure waves

Many types of gases, such as natural gas, hydrogen, and so on, are transported via pipelines using a chemical process, though leakages in these pipelines create waste and pose hazards and risks to industries, the environment and people. To monitor gas pipelines, a new leak detection and location method based on the amplitude attenuation model of dynamic pressure waves was designed and researched by experiments, compared with traditional method based on the propagation velocity and time differences as determined by the waveforms of the upstream and downstream signals. Both methods are achieved based on the propagation law of the dynamic pressure waves in the fluid flow. First, the fundamentals of the newly proposed method are clarified by considering the influence of gas flow on the waves. The experiments are then conducted in gas pipelines with 42 mm internal diameters. Finally, the results of the experiments are discussed and analyzed. The results indicate that all leakages can be detected by both methods but that the largest location error of the traditional method is −0.780%, whereas the largest location errors with respect to the new method are 0.054% with the experimental attenuation coefficients and 2.055% with the theoretical attenuation coefficients. It is further determined that the influence of the gas flow effects cannot be ignored by either method. Accordingly, the conclusions drawn suggest that the proposed methods can be applied to monitor gas pipelines.     

基于冰蓄冷中央空调的自动控制研究与设计

冰蓄冷空调是利用夜间低谷负荷电力制冰储存在蓄冰装置中,白天融冰将所储存冷量释放出来,这样可减少电网高峰时段用电负荷及空调系统装机容量,它代表着当今中央空调的发展趋势.通过对冰蓄冷中央空调的水温、水压、流量和空气温度、湿度、风量、压力、风阀开度等各种参数进行监控,并且在预测空调负荷的基础上确定冰蓄冷空调系统工作模式,从而...     

变风量空调系统的预测控制应用研究

变风量空调具有非线性和大时滞等特点,通过建立静压点压力与流量变化的关系确立模型,结合预测控制优化参数的控制策略,系统在流量变化的冲击下达到压力恒定和控制的快速响应,从而改善空调系统的性能和达到节能的目的。系统利用相关的参数进行了仿真研究,结果表明该控制策略有助于解决静压点压力在流量变化较大时能相对保持恒定。