High-Pressure Entrainment Measurement/Modeling, 18-R8156Printer Friendly Version
Inclusive Dates: 06/07/10 Current
Background - Wet gas scenarios are encountered during natural gas production, transmission and processing. The amount and distribution of liquid in the gas stream plays an important role in selecting and operating of flow measurement devices, designing transmission lines, designing gas processing and separation equipment, and corrosion occurrence and mitigation inside the pipe. In this last scenario, the distribution of the gas and liquid phases is very important, as it affects the contact of corrosion inhibitors with the wall of the pipe.
Several experimental programs have been conducted to investigate and characterize wet gas flows in pipes. Most of these studies are based on experimental data collected at low pressures (<100 psig). However, the pressure has a significant effect in the distribution and behavior of two-phase flow mixtures. In a mixture of natural gas and hydrocarbon liquid, the gas will dissolve in the liquid phase as the pressure is increased. The density of the gas increases with the pressure, which affects the separation of the gas and liquid phases as a consequence of a decreased density gradient. One of the motivations for this project is to fill the gap in the understanding of wet gas and rate of liquid droplet entrainment at high pressures.
Approach - The objective of the project is to develop modeling and experimental tools for characterizing multiphase and wet gas flows in high-pressure environments. The project includes: (1) designing and fabricating two devices to be used in testing programs at SwRI's Multiphase Flow Facility to investigate and characterize multiphase flows; (2) an experimental program to measure the rate of liquid entrained in a high-pressure gas stream (up to 3,600 psig); and (3) developing and validating a mathematical model for predicting the liquid entrainment rate.
Accomplishments - The project started with the review of the different methods and technologies that could be incorporated in the design of a liquid entrainment measurement device. Some of the options identified will be evaluated through proof-of-concept testing. A high-pressure flow visualization device is in the design phase. This device consists of an optical window, which allows for visualization of the entire cross section inside a pipe, and a camera system. The main features of this device are that it can operate at pressures up to 3,600 psig and that it does not introduce any perturbation into the flow. The high-pressure flow visualization device will allow identifying and verifying flow regimes in a multiphase stream and will allow a better understanding of the distribution of the phases inside a pipe. Another activity that is in progress is the modeling task, which started with a literature review to identify existing available models. Two modeling approaches have been identified: one is a mechanistic modeling approach, and the second one is an empirical correlation approach.