dehydration.pptx
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PROSESPERPINDAHAN
Fenomena Perpindahan Massa Molekuler (Diffusi) Steady State Satu Dimensi
Presented by:Dyan Hatining Ayu Sudarni 2314 201 001Rizqy Romadhona Ginting 2314 201 002
POST GRADUATE PROGRAMChemical Engineering Department - ITS
4.3.2 Natural Gas Hydrates
POST GRADUATEChemical Engineering Department-ITS
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Natural gas hydrates are solid crystalline compounds
formed by the chemical combination of natural gas and
water under pressure at temperature considerably above
the freezing point of water. The chemical formulae for
natural gas hydrates are:
1. Methane
2. Ethane
3. Propane
4. Carbon Dioxide
POST GRADUATEChemical Engineering Department-ITS
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Hydrates tend to form when there is:
Free water present and temperature decreases below that of hydrate-formation. This usually happens in the flow string or surface line;
Sudden pressure drop due to expansion. This usually happens when fluids flows through orifices, back pressure regulators, or chokes.
POST GRADUATEChemical Engineering Department-ITS
Hydrate formation can be predicted by using Figure 4–8 (for γg = 0.6, hydrates tend to form to the left of the “hydration formation” line)
Figure 4–10 (for first approximations of hydrate formation conditions at different values of gas gravity).
POST GRADUATEChemical Engineering Department-ITS
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There are four ways to dehydrate the natural gas:
1. direct cooling,
2. compression followed by cooling,
3. absorption,
4. adsorption.
first two usually cannot sufficiently dehydrate the gas to
pipeline requirements.
4.3.3 Adsorption Dehydration
POST GRADUATEChemical Engineering Department-ITS
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The adsorption dehydration unit usually contains an inlet gas stream separator
for initial separation, two or more adsorption towers (also called adsorbers or
contactors) to dehydrate gas, a high temperature heater to dry solid desiccant in
the towers, a regeneration gas cooler to condense water from the hot
regeneration gas, and a regeneration gas separator to remove water from the
regeneration gas stream (Leecraft, 1987).
In addition, piping, manifolds, switching valves, and controls are needed to
direct and control the flow of gases according to process requirement.
focus is given to the most popular technique of water removal-counter-current
absorption.
4.3.3 Absorption Dehydration
POST GRADUATEChemical Engineering Department-ITS
Absorption dehydration is the water removal process
by counter flowing natural gas through a certain liquid
solvent that has special attractions or affinities for
water. The liquid solvent is called a dehydrating agent
or liquid desiccant.
POST GRADUATEChemical Engineering Department-ITS
The most desirable dehydrating agents that can be used for commercial
dehydration purposes should possess the following important properties
(Campbell, 1998):
High water absorption efficiency;
High decomposition temperature;
Low vaporization losses;
Easy and economic to be separated and regenerated;
Non-corrosive and non-toxic to the system.
Dehydrating Agents
POST GRADUATEChemical Engineering Department-ITS
Glycol Dehydration Process
POST GRADUATEChemical Engineering Department-ITS
.
Thank you