Wet Gas Compression: Characterizing Two-Phase Flow Inside a Compressor With Flow Visualization

2017 ◽  
Author(s):  
Melissa Poerner ◽  
Ryan Cater ◽  
Craig Nolen ◽  
Grant Musgrove ◽  
David Ransom
Keyword(s):  
Flow Visualization ◽  
Flow Structure ◽  
Two Phase Flow ◽  
Gas Production ◽  
Liquid Volume ◽  
Phase Flow ◽  
Two Phase ◽  
Wet Gas ◽  
Gas Compression ◽  
Compressor Performance

Wet Gas Compression (WGC) continues to be an important topic as oil and gas production is driven further out into the ocean and moves critical equipment to the ocean floor. In the last year, significant milestones have been reached for WGC by the installation of the first wet gas compressor off the coast of Norway. Even with this achievement, there is a lack of understanding of the physics behind WGC and there are deficiencies in the ability to predict the compressor performance. Understanding the two phase flow structure inside the compressor is important for validating WGC simulations and being able to predict compressor performance. This paper reviews the results from a test program focused on characterizing the flow inside the compressor by using flow visualization. An open impeller centrifugal compressor was outfitted with windows to view the flow inside the compressor at the inlet, inside the impeller and in the diffuser section. Testing was conducted with an ambient suction pressure at various compressor speeds, flow rates, and liquid volume fractions. Images and videos were captured at the different conditions in order to observe the two phase flow structure. The general patterns and trends that characterize wet gas flow are discussed in this paper.

An Analytical Two-Phase Flow Model for Prediction of Leakage in Wet Gas Labyrinth Seals and Pocket Damper Seals. Is Simplicity Still Desired?

2021 ◽  
Author(s):  
Jing Yang ◽  
Luis San Andrés
Keyword(s):  
Simple Model ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Liquid Volume ◽  
Gas Mixture ◽  
Phase Flow ◽  
Rotor Speed ◽  
Labyrinth Seals ◽  
Two Phase ◽  
Wet Gas

Abstract Current and upcoming two-phase pump and compression systems in subsea production facilities must demonstrate long-term operation and continuous availability. Annular pressure seals, limiting secondary flow, also influence the dynamic stability of turbomachinery. Hence, it becomes paramount to quantify the leakage and dynamic force coefficients of annular seals operating with two-phase flow, a liquid in gas mixture or wet gas. Until now, a simple model for labyrinth seals (LSs) and the more modern pocket damper seals (PDSs) is not available, though these seal types find wide applications in subsea machinery. The paper develops a simple analytical model predicting the leakage and cavity pressures for LSs and PDSs operating with two-phase flow. The model adapts Neumann’s leakage equation for use with the physical properties of a homogeneous two-phase flow mixture. Predictions of leakage for a four-blade, eight-pocket, fully partitioned PDS operating under a low supply pressure (PS = 2.3 bar and 3.2 bar) and a low rotor speed equal to 5,250 rpm (surface speed = 35 m/s) agree well with experimental results procured for both a pure gas and a wet gas conditions (2.2% in liquid volume). Predicted leakage and cavity pressures also agree with those found by a multi-million node computational fluid dynamics (CFD) model. For an eight-blade, sixteen-pocket PDS supplied with air at PS = 62.1 bar, discharge pressure Pa = 31.1 bar and rotor speed of 15 krpm (surface speed = 91 m/s), the analytical model predicts leakage that is just 2% larger than a published CFD prediction. For the PDS supplied with an oil in gas mixture having gas volume fraction βS = 0.92 ∼ 0.98, the simple model delivers leakage that is up to ∼ 6% lower than published CFD results. An analysis of the two-phase leakage predictions via a modified flow factor reveals a loss coefficient (cd) impervious to the range of supply and discharge pressures considered and growing in proportion to the liquid volume fraction. Throughout the life of an oil well that sees radical changes in gas and liquid composition as well as pressure conditions, the expedient model, quick and accurate to estimate leakage in wet gases seals, can be readily integrated into an engineering routine or practice.

scholarly journals Power Loss Mechanism and Flow Structure in Two-phase Flow Driven by a Rotating Disk

2019 ◽  
Vol 33 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Kohei HIGASHIKAWA ◽  
Tomoaki WATAMURA ◽  
Kazuyasu SUGIYAMA
Keyword(s):  
Flow Structure ◽  
Power Loss ◽  
Two Phase Flow ◽  
Rotating Disk ◽  
Phase Flow ◽  
Two Phase ◽  
Loss Mechanism

Experimental Characterization of Oil-Refrigerant Two-Phase Flow

2000 ◽  
Author(s):  
V. T. Lacerda ◽  
A. T. Prata ◽  
F. Fagotti
Keyword(s):  
Flow Visualization ◽  
Two Phase Flow ◽  
Working Fluid ◽  
Phase Flow ◽  
Oil Viscosity ◽  
Two Phase ◽  
Mixture Flow ◽  
Horizontal Tubes ◽  
Constant Diameter ◽  
Oil Flow

Abstract Several phenomena occurring inside refrigerating systems depend on the interaction between the refrigeration oil and the refrigerant working fluid. Regarding the refrigeration cycle, good miscibility of oil and refrigerant assure easy return of circulating oil to the compressor through the reduction of the oil viscosity. Inside the compressor the lubricant is mainly used for leakage sealing, cooling of hot elements and lubrication of sliding parts. In the compressor bearing systems the presence of refrigerant dissolved in the oil greatly influences the performance and reliability of the compressor due to the outgassing experienced by sudden changes in temperature and pressure resulting in a two-phase mixture with density and viscosity strongly affecting the lubricant characteristics. A general understanding of the oil-refrigerant mixture flow is crucial in developing lubrication models to be used in analysis and simulation of fluid mechanics problems inside the compressor. In the present investigation the refrigeration oil flow with refrigerant outgassing is explored experimentally. A mixture of oil saturated with refrigerant is forced to flow in two straight horizontal tubes of constant diameter. One tube is used for flow visualization and the other is instrumented for pressure and temperature measurements. At the tubes inlet liquid state prevails and as flow proceeds the pressure drop reduces the gas solubility in the oil and outgassing occurs. Initially small bubbles are observed and eventually the bubble population reaches a stage where foaming flow is observed. The flow visualization allowed identification of the two-phase flow regimes experienced by the mixture. Pressure and temperature distributions are measured along the flow and from that mixture quality and void fraction were estimated.

scholarly journals Two-Phase Flow Visualization in the throttle of expansion valve

2007 ◽  
Vol 27 (Supplement1) ◽  
pp. 123-124
Author(s):  
Kazuhiko MATSUMURA ◽  
Yasuhiko FUJII ◽  
Shigeo KIMURA ◽  
Takahiro KIWATA
Keyword(s):  
Flow Visualization ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Expansion Valve
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