Typically, the allowable water content in gas transmission lines ranges from 4 lb. Of the other three glycols, triethylene glycol TEG is the most commonly used glycol for dehydration of natural gas because of the advantages relative to diethylene glycol DEG: This water can cause several problems for downstream processes and equipment.
The degree of automatic control of the equipment can vary considerably and depends largely on the specifications by the owner company. The suppliers of structured packing have developed the relationship of packing height per theoretical equilibrium stage. Electrical components are housed in explosion proof enclosures for operation in hazardous areas.
The housing is carbon steel with a corrosion resistant coating. The wet gas enters into an inlet separator to insure removal of contaminants and free water. If the level is lower than normal, this might be the first indication of trouble, such as: In field installations, a natural gas powered pump or a glycol powered pump can be used.
The glycol is thermally regenerated to remove excess water and regain the high glycol purity. At low temperatures, the water can either freeze in piping or, as is more commonly the case, form hydrates with CO2 and hydrocarbons mainly methane hydrates.
Glycol purity Glycol circulation rate up to a certain limit Number of contacting stages trays or packing height Amount of water in the inlet gas, which depends on the pressure and temperature of the gas These parameters must be considered at the design stage of the contactor, in addition to the maximum rate, pressure, and temperature of the gas.
Coil in the top of the reboiler still Coil in the surge tank or separate heat exchanger between rich and lean glycol Pipe-in-pipe heat exchanger ahead of the glycol absorber or a coil in the top of the absorber In some cases, an additional heat exchanger is necessary to exchange heat with air, to cool the lean glycol ahead of the contactor.
Various types of random packing are illustrated in Fig. The surge drum is usually located below the reboiler or at least at a level below the glycol in the reboiler. The level of glycol in the surge drum should be about at the two-thirds full level.
The dehydration of natural gas must begin at the source of the gas in order to protect the transmission system. Adsorbents used include silica gel most commonly usedmolecular sieve common in NGV dryersactivated alumina and activated carbon.
If the gas is a rich gas, with some condensate as well as liquid water forming at the inlet conditions of pressure and temperature in the separator, then a three-phase separator is installed.
The gas rises through the bubble caps and is dispersed as bubbles through the glycol on the trays.
Since the reboiler temperature is limited to F or less to prevent thermal degradation of the glycol, almost all of the enhanced systems center on lowering the partial pressure of water in the system to increase stripping. Depending on composition, these hydrates can form at relatively high temperatures plugging equipment and piping.
For this to occur, it is necessary to create a large surface area between the gas and the liquid glycol. Glycol piping All the vessels through which glycol is circulated are interconnected with steel piping.
As the reboiler drives off water vapor through the still column, the hot, reconcentrated glycol flows from the reboiler to the sparger box to remove additional water vapor.
Impurities in the glycol solution might promote foaming in the contactor or still. Function of the inlet separator The first and foremost piece of equipment that the gas flows through is the inlet separator.
In more recent designs, 12 to 14 trays are installed in glycol absorbers to minimize glycol circulation. Disadvantage of the glycol injection scheme- tangible glycol losses due to its high solubility in the hydrocarbon condensate.
This vessel can be either a separate, detached vessel, or on smaller units, built in to the bottom of the contactor. Pipeline drips installed near well heads and at strategic locations along gathering and trunk lines will eliminate most of the free water lifted from the wells in the gas stream.
The fire tube is always submerged in the glycol by having the glycol flowing from the reboiler over a weir or pipe, which is higher than the top of the fire tube. To ensure that the large surface area is provided by the downward flowing glycol, it is also essential that the steel be thoroughly clean, so that all of the steel is wetted by the glycol.
The glycol strainer ensures that no solid particles enter into the glycol pump.Natural Gas Dehydration Lessons Learned from the Natural Gas STAR Program ConocoPhillips The Colorado Oil and Gas Association, and. •Sweetening process is to remove acid gases from natural gases.•This can be done either by adsorption or absorption processes.•The most famous adsorption process is solid desiccant beds which canperform Sweetening and dehydration for natural gas at the same time withhigher efficiency.•The most famous absorption process is amine.
Glycol Dehydrators, part of natural gas dehydration systems, remove water vapor from gas streams to prevent the formulation of hydrates and corrosion in pipelines. Exterran’s Glycol Dehydration Unit is a reliable, efficient system for removing water from natural gas well streams in order to meet typical pipeline and.
Thus, of the four glycols, TEG is the best suited for dehydration of natural gas. In glycol dehydration, TEG is usually referred to only as “glycol.” Unless otherwise specified, that convention is used in the rest of this page.
This paper compares three methods for natural gas dehydration that are widely applied in industry: (1) absorption by triethylene glycol, (2). Gas dehydration by liquid media is most widely used in the gas industry. The liquid sorbents used for the dehydration of natural and petroleum gases should have high solubility in water, be low cost, and should show high corrosion resistance.Download