聚结分离器油水分离效率模拟试验研究

为了能经济、快速地研究聚结分离器内部流场,简化影响因素,提高含油污水分离效率,首先利用软件对聚结分离内部堰板结构的流场进行模拟分析。模拟得到当入口流速为0.088m/s,入口管流和堰板的夹角60°时,流场稳定,有利于后续沉降分离。然后在室内搭建试验平台,在模拟条件下,以分离效率为研究对象,在研究板间距、板组数量、温度对油水两相聚结分离的影响。试验结果得到当聚结板板间距为1/4 in、采用双组板时,聚结分离器分离效率最高。     

一种高效油水分离器的应用

针对传统油水分离器达不到分离要求的问题,介绍了一种高效油水分离器,通过调节重液出料堰的高度,适应组成与密度变化的混合液的分离,同时混合液的宏观流动方向与轻重液的分离方向垂直.应用表明：该油水分离器混合液组成调节范围宽,生产负荷调节范围宽,返混程度低,分离效果好.     

结构与操作参数对油水重力分离器性能的影响

在全面测定油水重力分离器内分散相油滴浓度的基础上,改变其结构参数和操作参数,对影响油水两相浓度分布的主要因素进行了对比试验.结果表明,在一定范围内,减小油水重力分离器的板长和板间距、增加板倾角、减小入口流量以及增加入口含油浓度均可使油水分离效果在一定程度上提高;在一定的范围内适当增加水相的沉降时间,可以改善油水混合物在重力沉降区域的层流状态;而在达到一定的沉降时间之后,样品中的含油量已趋于恒定,不能仅仅依赖于增大沉降时间来提高分离效果.     

Analysis of the impact of flow characteristics on the separation efficiency and pressure drop of a cyclone-type oil separator

The effects of flow structure on the separation efficiency and pressure drop in a cyclone-type oil separator were investigated via Reynolds-averaged Navier-Stokes (RANS) simulations and large eddy simulations (LES), and the results were compared with experiments. Compared with the RANS simulations, the LES results were more similar to the experimental data as they simulated the complex flow structure more realistically. Swirling flow with strong turbulent kinetic energy (TKE) at the top section hindered the flow of particles toward the separator wall. In addition, a decrease in tangential velocity along the wall at the bottom reduced the centrifugal force, resulting in a decreased separation efficiency as particles were able to flow directly toward the outlet. The LES also predicted the pressure drop slightly better than the RANS simulation did, due to increased pressure drop caused by collision of the flow with the helix and outlet tube, which led to the formation of vortical flow structures with strong TKE.

     

复合T形管内稠油-水预分离性能的研究

气液或液液两相流通过T形管时会发生相分配不均现象,其相分配不均程度与介质物性、T形管结构及工作参数有着密切关系。以稠油和水为工作介质,采用含有3个分支管的复合T形管分离器进行稠油-水两相分离特性试验研究。结果表明:复合T形管在稠油-水预分离方面具有一定的可行性。试验工况范围内,随着入口流速和分流比的减小,下水平主管出口的含水率增加,分离效率较高;增加入口含油率在一定程度上能够提高稠油中游离水的脱除程度,而分离效率呈现小幅度的增加趋势;当入口含油率为10.67%和17.5%,分流比接近入口含油率时,上水平管出口含水率可以降到30%以下,满足电脱分离器深度脱水的进液要求。     

基于Flow Simulation的油气分离器流场分析及优化设计

用数值模拟的方法研究喷油螺杆压缩机油气分离器部件内的流场,对气液两相流场采用离散相模型计算。通过对油气分离器建立多个单一变量模型并设定相应边界条件,对计算结果分析发现,除合理设定内筒内外截面面积比外,油气分离器入口截面形状及出气口相对位置对提高分离效果也具有积极作用,据此提出优化设计方案和为认识油气分离器内部流场提供参考。     

Numerical investigation of two-phase flow characteristics in multiphase pump with split vane impellers

Multiphase pump is a cost-effective option for subsea oil and gas field development. The ability to handle different inlet gas volume fractions (GVFs) especially high inlet GVF is critical to the development of pump performance. In this study, the two-phase flow characteristics in normal impeller and split vane impeller at different inlet GVFs were investigated by steady numerical simulations. The gas distribution on blade-to-blade plane and meridional flow channel at different inlet GVFs were analyzed and compared. Gas accumulation area and movement characteristics of the gas-liquid flow in impeller flow passage were also pointed out by unsteady simulations. Experimental results of the pump differential pressure were compared with the numerical simulation results, to validate the accuracy of numerical simulation method. The flow characteristics in pump with modified impeller and its performance at different inlet GVFs were both compared with that of the normal impeller. The steady simulation results of normal impeller in different inlet GVFs show that gas concentrating area in the flow passage increases as inlet GVF grows. The unsteady simulation results indicate that gas pocket firstly occurs on the pressure side of impeller, then moves to the suction side in the middle area of blade and finally transfers to outlet of impeller and disappears. The errors between numerical simulation results and experiment data are below 10 %, which validated the feasibility of the numerical simulation method. Simulation results on the split vane impeller demonstrate that the gas accumulation area in flow passage of the modified impeller is dramatically decreased compared to that of the normal impeller. The performance of the modified impeller is generally better than the normal impeller especially in high inlet GVF conditions.

     

Experimental and numerical investigation of self-priming siphon side weir on a straight open channel

Siphons are basic and powerful hydraulic instruments which can be used as dam spillway or weir. In a siphon, atmospheric pressure pushes the water into the region of vacuum at the crest of the siphon, and then water falls towards the outlet of siphon. In this study, the siphon used as a side weir was investigated to determine hydrodynamic characteristics experimentally, theoretically and numerically. First, the flow properties of main channel were examined for subcritical flow condition. Then, the velocity and pressures distributions inside the siphon; finally the discharge performance of siphon side weir was determined comparatively, and the results were discussed.     

新型波纹板油水分离器的应用研究

进行了污水除油技术的强化分析。通过对采用斜通道波纹板填料作为内部分离组件的新型油水分离器的应用研究，证明了将浅池原理和聚结技术结合起来的新型分离器具有较高的分离效率。     

聚结—旋流分离装置流场特性的数值模拟分析研究

为了提高水力旋流器的分离效果,提出了一种新型旋流分离装置。根据计算流体动力学方法,应用Fluent软件,以同向出流倒锥式旋流器为原型,模拟了一种新型旋流分离装置——聚结—旋流分离装置,并与同向出流倒锥式旋流器进行对比分析。优选出聚结—旋流分离装置的最佳入口流量、入口含油体积分数、切向水相出口分流比。     

Numerical simulation of the effects of the internal components on the uniformity of the flow field in a tubular separator

This paper adopts the standard k-ε model and mixture model of the FLUENT code to numerically analyze the components characteristics of the gravity separator. It intends to involve several combinations of four types of rectifiers and two types of coalescers of corrugated plates to optimize the structure of the components. Numerical simulation analysis is carried out on the synergistic effect of the reflective inlet component, the rectifier of square grids, and the coalescer of perforated corrugated plates under variable working conditions. The results illustrate that when the distance between the rectifier and the separator’s head is L₁ = 3/4 D, the width L₂ = 1/4 D, and the plate spacing L₃ = 1/10 D, the separation effect gets improved. Additionally, the perforated corrugated plates prove better effects of rectification and coalescence. And when the distance between the coalescer and the head is L₄ = 25/183 L and the elevation angle α = 2.5°, the separation performance will be further improved. What’s more, the influence of the Reynolds number (Re_i, from 5640 through 8297 in the inlet component) and the volume fraction of the dispersed phase (from 5 % through 30 %) on the separation effects of various combination conditions of the internal components has also been investigated. As the former increases, the combined of reflective inlet component, rectifier and coalescer will perform the best separation effects. As the latter increases, the separation efficiency of low-oil ratio of oil-water mixture of the jointly structured separator will increase the most.

     

Centrifugal compressor tip clearance and impeller flow

Compressors consume a considerable portion of the electricity used in the industrial sector. Hence, improvements in compressor efficiency lead to energy savings and reduce environmental impacts. The efficiency of an unshrouded centrifugal compressor suffers from leakage flow over the blade tips. The effect of tip leakage flow on the passage flow differs between the full and splitter blade passages. In this study, the differences in the flow fields between the full and splitter blade passages were studied numerically in detail. An industrial high-speed compressor with a design pressure ratio of 1.78 was modelled. Numerical studies were conducted with six different tip clearances and three different diffuser widths. The results show that increasing tip clearance considerably increases the reversed flow into the impeller with an unpinched diffuser. The reversed flow then partly mixes into the flow in the same blade passage it entered the impeller and the rest migrates over the blade, mixing with the tip clearance flow. Furthermore, as the reversed and clearance flow mix into the wake, the wake is weakened. As pinch reduces both the reversed flow and clearance flow, the passage wakes are stronger with pinches. However, the pinch is beneficial as the losses at the impeller outlet decrease.

     

Effect of specific energy variation on lateral overflows

A numerical model was used to study the effect of change in specific energy height along a side weir on flow. Discharge coefficient was considered as a local variable that includes flow depth and the angle of the deflected water jet along side weir. Hydraulic profile on the weir plane and the hydraulic head on the weir were obtained using two dimensionless parameters ψ and m as a function of Froude number. Flow depths and flow rates were then computed and minimum standard errors were determined based upon these parameters. The agreement between computed values and observations was demonstrated. It was concluded that rates of flow are considerably affected by the variation of specific energy along the side weir when weir head is based on flow depth at the weir plane. Considerable deviations from the constant specific energy assumption may be observed in this case specially when a great change in flow rates exists along side weirs with zero end discharges.     

储罐机械清洗设备的工艺改进

通过对传统储罐机械清洗设备的构成及工艺流程的应用研究,发现传统设备中的部分装置和部分环节自动化程度不高,费时费力,如油水分离装置的人工撇油、清洗机罐顶手动切换、无远程监控和人工记录数据等。通过对这些方面的改进,实现了油水分离装置的油水分离自动化、清洗机的自动切换、中央控制室集中远程监控及数据采集等技术的完善和管理系统的创新,保证了整个清洗过程自动化程度更高,节省了人力、物力和财力,更好的满足了各种储罐的清洗要求,值得应用和推广。     

Estimating the uncertainty of discharge coefficient predicted for oblique side weir using Monte Carlo method

Side weir is a hydraulic structure, which is used in irrigation systems to divert some water from main to side channel. It is installed at the entrance of the side channel to control and measure passing water into the side channel. Many studies provided side weir water surface profile and coefficient of discharge to measure water discharge diverted into the side channel. These studies dealt with different side weir shapes (rectangular, trapezoidal, triangular and circular), which were installed perpendicular to the flow direction. Recently, some studies dealt with skew side weir, but these studies still need to more investigation. Here we report to investigate oblique side weir theoretically using statistical method to supported other studies in this case. Measurement uncertainty discharge coefficient C_d was obtained by two methods: analytical according to the ‘Guide to the expression of uncertainty in measurement’ and the Monte Carlo method. The results indicate that all experimental results are consistent with the analytical results. The relative expanded uncertainty of the discharge coefficient C_d does not exceed 2%.     

Multi – oil droplet recognition of oil-water two-phase flow based on integrated features

Multi-oil droplet target recognition is one of the applications of machine vision in the measurement of oil-water two-phase flow parameters, which could combine other algorithms to obtain the oil droplet velocity and the water holdup of oil water two-phase flow. Appropriate target representation features can improve the recognition effect of multiple oil droplets. However, due to shooting environment differences and quality differences of oil-water two-phase flow images, existing target representation features do not perform well in low-quality oil-water two-phase flow images. To improve the precision of multi-oil droplet target recognition in oil-water two-phase flow and reduce the miss rate, this paper constructs an integrated feature on the basis of aggregate channel features (ACF). The integrated feature named aggregate channel features with histogram of local gravitational feature（ACFHG） contains the color feature channels reflecting the overall color features of the oil droplet sample, the gradient amplitude channel reflecting the overall gradient of the oil droplet sample image, the gradient direction histogram feature channels reflecting the local gradient of the oil droplet sample image, and the local gravitational feature channels that ensure oil droplet target recognition in low quality photos and photos taken in complex shooting environments. Moreover, the rotation invariance is obtained by taking the oriented gradient histogram of the local gravitational feature to further improve the multi-oil droplet target recognition effect. Experiment results show that the average precision of multi-oil droplet target recognition using the integrated features is 83.38%, which is 9.93% higher than that with using ACF, and the miss rate is 9.13%, which is 57.18% lower than that with using ACF. Compared with other existing target detection methods, the method proposed in this paper still has an advantage in the rate of missed detection.     

新型波纹板油水分离器结构性能研究

进行了污水除油技术的强化分析，通过对实验模拟装置结构性能的研究，证明了将浅池原理和聚结技术结合起来的新型油水分离器具有较高的分离效率和较好的结构性能。     

A flow rate measurement method for horizontal oil-gas-water three-phase flows based on Venturi meter,blind tee,and gamma-ray attenuation

Online horizontal oil-gas-water three-phase flow rate monitoring is essential for reliable operations during industrial production. A flow rate measurement method is developed in horizontal oil-gas-water three-phase flows by combining a blind tee, a Venturi meter, and a gamma-ray densitometer. The blind tee is installed at the test section entrance to homogenize the mixture by transforming the horizontal flow to a vertical upward flow. The Venturi meter is used for the total flow rate measurement. The dual-energy gamma-ray densitometer is used for phase holdup measurement. In the present method, blind-tee mixing effects and oil-water mixture slip behavior is essential, which were experimentally analyzed in this work. The phase inversion was found in the oil-water mixture with the increasing of the oil volume fraction. Besides, the addition of the gas reduces the oil-water slip ratio. For the range of 0–35% and 65–100% oil fraction in the oil-water liquid, the oil-water mixture can be well treated as a pseudo homogenous liquid with a slip ratio of 0.9–1.1. A three-phase flow rate model is then established for these conditions. The method was validated by horizontal oil-gas-water three-phase flows with average relative errors of 3.2% for the total flow rates, 4.3% for the gas flow rates, 11.5% for the oil flow rates, and 7.8% for the water flow rates.     

Experimental analysis of flow characteristics over hydrofoil weirs

The rounded crested weirs are commonly used for discharge measurements and this overflow structures have advantages such as stable overflow pattern and good accuracy. Hydrofoil weirs with streamlined properties are similar to the ogee weirs and can be used as a spillway profile. The hydraulic features of flow over hydrofoil weirs created by the NACA0018, NACA0021 and NACA0024 hydrofoil geometry placed in an open channel are investigated experimentally under free-flow conditions. The velocity field of hydrofoil weir flows are measured by one-dimensional Laser Doppler Anemometer. Experimental velocity profiles are measured along the middle section of the channel, especially around the weir structure, to determine the boundary layer separation. According to the determination of optimum weir structure the free surface profiles, pressure distributions on weir surfaces, experimental discharge coefficients and head losses over weir structures are determined for different structure and flow conditions. Pressure distributions over the hydrofoil weir are presented. In addition, the relationships between discharge coefficient (C_d) and flow rate (Q), specific total head (H/R), relative weir height (P/H), relative total head (H/P) and dimensionless total energy head upstream of the weir (H/L) are investigated.     

流体系统加热回路计算分析

介绍一种无需加热器的流体加热系统。该系统的油箱经过加热泵后同供油管线相连接,并在加热泵和供油管线之间的连接管路上设有出口球阀;在加热泵和出口球阀之间的管路上设有同油箱相连通的溢流管路;并在该溢流管路上安装压力调节阀、节流孔板和层流孔板。该回路的优点在于加热均匀,加热元件表面不积垢,有利于保持油液清洁,节省了传统加热器,非常适用于不需要经常加热的环境。另外,该回路结构简单,加工方便,磨损件只有节流孔板,回路整体运行成本低廉。