MODELING OF NATURAL GAS DEHYDRATION IN A SUPERSONIC SEPARATOR: CONDENSATION PROCESS

The purpose of this report is to provide an overview of the author's Final Year Project.
Natural gas, as it is used by consumers, is much different from the natural gas that IS
brought from underground up to the wellhead. The natural gas used by consumers IS
composed almost entirely of methane. However, natural gas found at the wellhead, IS
by no means as pure. The gas commonly exists in mixtures with hydrocarbons, water
vapor, hydrogen sulfide (H2S), carbon dioxide (C02), helium, nitrogen and other
compounds.
Most of the liquid. free water associated with extracted natural gas is removed by
separation methods at or near the wellhead. However, the removal of the water vapor
that exists in solution m natural gas requires a more complex treatment. This treatment
consists of 'dehydrating' the natural gas, which usually involves one of two processes:
either absorption. or adsorption. Absorption occurs when the water vapor is taken out
by dehydrating agent while adsorption occurs when the water vapor is condensed and
collected on the surface.
The research started with literature review to investigate suitable model to be used,
followed with the construction of nozzle geometry with specified meshes. The project
describes a conservative two-dimensional compressible numerical model for
supersomc spontaneous condensing steam flow based on the classical nucleation
theory.
The project aims to model the condensation behavior of liquid water in a supersonic
convergent-divergent nozzle separator. Currently, there is no research has been done to
study the behavior of the water vapor to water liquid formation and growth in relation
with the oil and gas field. Quantitative validation of the numerical model was
accomplished and the results showed a good agreement between numerical simulation
and the result from published literature.