Gas Carry-Under in Gas-Liquid Cylindrical Cyclone Separator: A Mechanistic Model

2019 ◽  
Author(s):  
Srinivas Swaroop Kolla ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Mechanistic Model ◽  
Liquid Level ◽  
Wall Jet ◽  
Gas Entrainment ◽  
Cylindrical Cyclone ◽  
Tangential Wall ◽  
Control Configuration ◽  
Extensive Experimental Data ◽  
Operational Envelope ◽  
Physical Phenomena

Abstract Gas Carry-Under (GCU) is one of the two undesirable phenomena that occur in the GLCC©,1 (Gas-Liquid Cylindrical Cyclone) separators when it operates even within the Operational Envelope (OPEN). Earlier studies have shown that maintaining a liquid level below the inlet of the GLCC under control configuration affects the GCU in GLCC. It has been identified that the tangential wall jet is the cause of gas entrainment within the GLCC and has been understood to change with liquid level maintained at the inlet. Also, it has been theorized that effective formation of the vortex formed in the lower part of the GLCC, or a stable gas core enhances the separation of gas entrained in the liquid. At present, there is no mechanistic model which captures these complex physical phenomena in the GLCC. This paper presents a newly developed mechanistic model which can predict the GCU for different flow conditions, fluid properties, and various liquid levels. The proposed model captures the various physical phenomena namely: saturated flow at the inlet, tangential wall jet phenomena, gas entrainment and vortex flow that results in separation of gas. The developed model has been compared with the extensive experimental data and is said to be in good agreement.

Tangential Wall Jet Flow and Gas Entrainment in Gas-Liquid Cylindrical Cyclone Compact Separator

2019 ◽  
Author(s):  
Srinivas Swaroop Kolla ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Liquid Film ◽  
Mechanistic Model ◽  
Experimental Investigations ◽  
Wall Jet ◽  
Velocity Change ◽  
Gas Entrainment ◽  
Cylindrical Cyclone ◽  
Wall Jet Flow ◽  
Carry Over ◽  
Operational Envelope

Abstract Gas Carry-Under (GCU) is one of the undesirable phenomena that exist in the Gas-Liquid Cylindrical Cyclone (GLCC) separators even within the liquid carry-over Operational Envelope (OE). In order to quantify the GCU, it is important to understand the cause of gas entrainment that occurs in the GLCC other than the incoming entrained gas within the liquid medium. The tangential inclined inlet of 27° with reduced area allows the stratified liquid flow to exit the inlet nozzle tangentially along the wall into the vertical lower part of the GLCC, whereby the liquid film spreads along the wall in an asymmetrical shape. The gas moves to the center of the GLCC and escapes through the gas leg. The liquid film flow is complex and turbulent exhibiting unevenness of the film thickness and asymmetrical velocity distribution. Experimental investigations show that the magnitude of liquid wall jet film tangential and axial velocity change as a function of length along the GLCC below the inlet of the GLCC. This wall jet film flowing down along the wall is the cause for gas entrainment and GCU. The experimental results show that the gas entrainment mechanism is not like the conventional jet entrainment as expected to be occurring in GLCC. The change in velocities of the wall jet film at various liquid heights maintained below the inlet results in varying gas entrainment at various inlet liquid levels and for fluid properties. The wall jet phenomena that takes places at the inlet has been discussed in detail and a mechanistic model capable of predicting the wall jet parameters has been presented in this paper. Further, a novel mechanistic model that is developed for the first time is also presented which can predict the gas entrainment at various liquid levels and flow conditions using the wall jet parameters as an input condition.

Wet Gas Separation in Gas-Liquid Cylindrical Cyclone (GLCC) Separator

2007 ◽  
Author(s):  
Robiro Molina ◽  
Shoubo Wang ◽  
Luis E. Gomez ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
...  
Keyword(s):  
High Pressure ◽  
Separation Efficiency ◽  
Mechanistic Model ◽  
Velocity Ratio ◽  
Wet Gas ◽  
Cylindrical Cyclone ◽  
Improved Performance ◽  
Carry Over ◽  
Operational Envelope ◽  
Annular Film

A novel Gas Liquid Cylindrical Cyclone (GLCC©), equipped with an Annular Film Extractor (AFE), for wet gas applications has been developed and studied experimentally and theoretically. Detailed experimental investigation of the modified GLCC has been carried out for low and high pressure conditions. The results show expansion of the operational envelope for liquid carry-over, and improved performance of the modified GLCC. For low pressures, the modified GLCC can remove all the liquid from the gas stream, resulting in zero liquid carry-over. For high pressure conditions, the GLCC with a single AFE has separation efficiency > 80% for gas velocity ratio of < 3. A mechanistic model and an aspect ratio design model for the modified GLCC has been developed, including the analysis of the AFE. The model predictions agree with the experimental data within ± 15% for low pressure and ± 25% for high pressure conditions.

Wet Gas Separation in Gas-Liquid Cylindrical Cyclone Separator

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Robiro Molina ◽  
Shoubo Wang ◽  
Luis E. Gomez ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
...  
Keyword(s):  
High Pressure ◽  
Separation Efficiency ◽  
Mechanistic Model ◽  
Velocity Ratio ◽  
Wet Gas ◽  
Cylindrical Cyclone ◽  
Improved Performance ◽  
Carry Over ◽  
Operational Envelope ◽  
Annular Film

A novel gas-liquid cylindrical cyclone (GLCC©, ©The University of Tulsa, 1994), equipped with an annular film extractor (AFE), for wet gas applications has been developed and studied experimentally and theoretically. Detailed experimental investigation of the modified GLCC has been carried out for low and high pressure conditions. The results show expansion of the operational envelope for liquid carry-over and improved performance of the modified GLCC. For low pressures, the modified GLCC can remove all the liquid from the gas stream, resulting in zero liquid carry-over (separation efficiency=100%). For high pressure conditions, the GLCC with a single AFE has separation efficiency >80% for gas velocity ratio, vsg/vann≤3. A mechanistic model and an aspect ratio design model for the modified GLCC have been developed, including the analysis of the AFE. The model predictions agree with the experimental data within ±15% for low pressure and ±25% for high pressure conditions.

Mechanistic Modeling of Liquid Carry-Over for 3-Phase Flow in GLCC© Compact Separators

2018 ◽  
Author(s):  
Srinivas Swaroop Kolla ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Mechanistic Model ◽  
Pressure Control ◽  
Mechanistic Modeling ◽  
Phase Flow ◽  
Fluid Properties ◽  
Control Configuration ◽  
Carry Over ◽  
Water Cut ◽  
Operational Envelope ◽  
Proper Operation

Gas-Liquid Cylindrical Cyclone (GLCC©) Separators have been in use in petroleum and other related industries for over two decades. Prediction of Liquid Carry-Over Operational Envelope (LCO-OE) is essential for designing and proper operation of GLCC©. Earlier mechanistic models for predicting LCO-OE were based on gas-liquid phase flow. A new mechanistic model has been developed for the prediction of the LCO-OE incorporating the effect of watercut and fluid properties for a GLCC© under liquid level and pressure control configuration. The new model captures the effect of viscosity and surface tension on the LCO-OE and the effect of water cut on the onset of annular mist velocity. Comparison between the developed mechanistic model predictions for LCO-OE with the experimental data show a good agreement.

scholarly journals Viscosity Model for Nanoparticulate Suspensions Based on Surface Interactions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2752
Author(s):  
Benedikt Finke ◽  
Clara Sangrós Sangrós Giménez ◽  
Arno Kwade ◽  
Carsten Schilde
Keyword(s):  
Mechanistic Model ◽  
Model Development ◽  
Rheological Behaviour ◽  
Hybrid Modelling ◽  
Shear Rates ◽  
Drag Forces ◽  
Boehmite Nanoparticles ◽  
Data Points ◽  
Two Parameters ◽  
Physical Phenomena

In this paper, a widely mechanistic model was developed to depict the rheological behaviour of nanoparticulate suspensions with solids contents up to 20 wt.%, based on the increase in shear stress caused by surface interaction forces among particles. The rheological behaviour is connected to drag forces arising from an altered particle movement with respect to the surrounding fluid. In order to represent this relationship and to model the viscosity, a hybrid modelling approach was followed, in which mechanistic relationships were paired with heuristic expressions. A genetic algorithm was utilized during model development, by enabling the algorithm to choose among several hard-to-assess model options. By the combination of the newly developed model with existing models for the various physical phenomena affecting viscosity, it can be applied to model the viscosity over a broad range of solids contents, shear rates, temperatures and particle sizes. Due to its mechanistic nature, the model even allows an extrapolation beyond the limits of the data points used for calibration, allowing a prediction of the viscosity in this area. Only two parameters are required for this purpose. Experimental data of an epoxy resin filled with boehmite nanoparticles were used for calibration and comparison with modelled values.

Control System Simulators for Gas-Liquid Cylindrical Cyclone Separators

2000 ◽  
Vol 122 (4) ◽  
pp. 177-184 ◽  
Author(s):  
Shoubo Wang ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
Jack D. Marrelli ◽  
Gene E. Kouba
Keyword(s):  
Control System ◽  
Control Strategy ◽  
Pressure Fluctuations ◽  
Pressure Control ◽  
Liquid Level ◽  
Control Loop ◽  
Level Control ◽  
Two Phase ◽  
Bulk Separation ◽  
Cylindrical Cyclone

The control system performance of gas liquid cylindrical cyclone (GLCC©) separators can be considerably improved by adopting suitable control strategy and optimizing the design of the controller PID settings. Dynamic simulators have been developed in this study, based on Matlab/Simulink® software for evaluation of several different GLCC control philosophies for two-phase flow metering loop and bulk separation applications. Detailed analysis of the GLCC control system simulators indicates that for integrated liquid level and pressure control strategy, the level control loop compliments the operation of the pressure control loop, and vice versa. This strategy is ideal for reducing the pressure fluctuations in the GLCC. At severe slugging conditions, the integrated liquid level control is more desirable because of its faster response. However, there is no control of the GLCC pressure fluctuations. The results also show that the simulators are capable of representing the dynamic behavior of real physical systems. [S0195-0738(00)00504-5]

Measurement of Gas Entrainment Rate From Free Surface by Vortex

2012 ◽  
Author(s):  
Yasuo Koizumi ◽  
Naosuke Ohte ◽  
Kamide Hideki ◽  
Shuji Ohno ◽  
Kei Ito
Keyword(s):  
Free Surface ◽  
High Speed ◽  
Silicone Oil ◽  
Liquid Velocity ◽  
Liquid Level ◽  
Test Fluid ◽  
Entrainment Rate ◽  
Flow State ◽  
Gas Entrainment ◽  
Test Vessel

A sodium-cooled fast breeder reactor is now at the developing stage in Japan. One concern for safety is cover gas entrainment into the sodium coolant. The gas entrainment rate into liquid by the vortex formed on the free surface was examined experimentally. Liquid flowed into a cylindrical vessel from a wall tangentially. Swirl flow was formed in the vessel, and then liquid drained from the bottom outlet of the vessel. A hollow vortex was formed on the free surface in the test vessel. Air was entrained under the free surface of the vortex and carried away from the bottom of the vessel. The flow state of the gas entrainment was visually observed by using a high speed video camera. The gas entrainment rate into liquid was measured. In the present experiments, test fluid was changed from water in the previous experiments to 20 cSt silicone oil. The liquid level in the test vessel was 25 mm in the present experiments. Only the vortex-type gas-entrainment was observed as in the previous experiments since the liquid level was low. The flow state observed at the flow visualization section of the outlet pipe was only a semi-annular flow. The initiation of the gas entrainment was delayed in the case of silicone oil compared with the case of water. The increasing rate of the gas entrainment to the liquid velocity is milder in the case of silicone oil than in the case of water.

Dynamic Simulation of the Micro-Milling Process Including Minimum Chip Thickness and Size Effect

2012 ◽  
Vol 504-506 ◽  
pp. 1269-1274 ◽  
Author(s):  
François Ducobu ◽  
Edouard Rivière-Lorphèvre ◽  
Enrico Filippi
Keyword(s):  
Size Effect ◽  
Cutting Forces ◽  
Mechanistic Model ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Milling Process ◽  
Cutting Conditions ◽  
Micro Milling ◽  
Minimum Chip Thickness ◽  
Physical Phenomena

Micro-milling with a cutting tool is a manufacturing technique that allows production of parts ranging from several millimeters to several micrometers. The technique is based on a downscaling of macroscopic milling process. Micro-milling is one of the most effective process to produce complex three-dimensional micro-parts, including sharp edges and with a good surface quality. Reducing the dimensions of the cutter and the cutting conditions requires taking into account physical phenomena that can be neglected in macro-milling. These phenomena include a size effect (nonlinear rising of specific cutting force when chip thickness decreases), the minimum chip thickness (under a given dimension, no chip can be machined) and the heterogeneity of the material (the size of the grains composing the material is significant as compared to the dimension of the chip). The aim of this paper is to introduce some phenomena, appearing in micromilling, in the mechanistic dynamic simulation software ‘dystamill’ developed for macro-milling. The software is able to simulate the cutting forces, the dynamic behavior of the tool and the workpiece and the kinematic surface finish in 2D1/2 milling operation (slotting, face milling, shoulder milling,…). It can be used to predict chatter-free cutting condition for example. The mechanistic model of the cutting forces is deduced from the local FEM simulation of orthogonal cutting. This FEM model uses the commercial software ABAQUS and is able to simulate chip formation and cutting forces in an orthogonal cutting test. This model is able to reproduce physical phenomena in macro cutting conditions (including segmented chip) as well as specific phenomena in micro cutting conditions (minimum chip thickness and size effect). The minimum chip thickness is also taken into account by the global model. The results of simulation for the machining of titanium alloy Ti6Al4V under macro and micro milling condition with the mechanistic model are presented discussed. This approach connects together local machining simulation and global models.

Design and Performance of Passive Control System for Gas-Liquid Cylindrical Cyclone Separators

1998 ◽  
Vol 120 (1) ◽  
pp. 49-55 ◽  
Author(s):  
R. S. Mohan ◽  
S. Wang ◽  
O. Shoham ◽  
G. E. Kouba
Keyword(s):  
Control System ◽  
Passive Control ◽  
Level Control ◽  
Control Approach ◽  
Flow Energy ◽  
External Power Source ◽  
Cylindrical Cyclone ◽  
And Performance ◽  
Operational Envelope ◽  
Classical Control

The performance of gas-liquid cylindrical cyclone (GLCC) separators can be improved by reducing or eliminating liquid carryover into the gas stream or gas carryunder through the liquid stream, utilizing a suitable liquid level control. In this study, a new passive control system has been developed for the GLCC, in which the control is achieved by utilizing only the liquid flow energy. A passive control system is highly desirable for remote, unmanned locations operated with no external power source. Salient features of this design are presented here. Detailed experimental and modeling studies have been conducted to evaluate the improvement in the GLCC operational envelope for liquid carryover with the passive control system. The results demonstrate that a passive control system is feasible for operation in normal slug flow conditions. The advantage of a dual inlet configuration of the GLCC is quantified for comparative evaluation of the passive control system. The results of this study could form the basis for future development of active control systems using a classical control approach.

Droplet Size Distributions and Pressure Control in the Gas-Liquid Cylindrical Cyclone

2020 ◽  
Author(s):  
Lele Yang ◽  
Jing Wang ◽  
Li Zou
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Flow Instability ◽  
Droplet Size Distribution ◽  
Pressure Control ◽  
Superficial Velocity ◽  
Liquid Level ◽  
Outlet Section ◽  
Cylindrical Cyclone

Abstract The gas–liquid cylindrical cyclone (GLCC) employs gravitational and centrifugal forces to realize gas-liquid separation. The aim of this study is to understand the droplet size distribution and pressure control in the GLCC via experiment and numerical analysis. The droplet size and pressure distributions were measured using Malvern RTsizer and pressure transmitters, respectively. The Discrete Phase Model was used to numerically analyze the swirling hydrodynamics of the GLCC. The results showed that the increase in the gas superficial velocity decreased the droplet size distribution at the inlet as a whole due to the shear effect and flow instability. The increase in the liquid superficial velocity only increased the small droplet size distribution at the inlet for the limitation of the gas’s carrying capacity. The pressure loss mainly occurred at the inlet and the overflow outlet. When the liquid level was remained below the inlet and above the liquid outlet, the liquid level and the liquid outlet section approximately met the Bernoulli equation for a finite large flow beam. With the increase in the pressure at the gas outlet, the liquid film fell back and the separation efficiency increased gradually. These results are helpful for further spreading applications of the GLCC in industry.

Sign in / Sign up

Export Citation Format

Share Document