Glycol dehydration contactor

Most glycol dehydration processes are continuous. That is, gas and glycol flow continuously through a vessel (the contactor" or absorber ) where they come in contact and the glycol absorbs the water. The glycol flows from the contactor to a reboiler (sometimes called "reconcentrator or regenerator where the water is removed or stripped from the glycol and is then pumped back to the contactor to complete the cycle. 

Function is to strip species from the liquid to produce a quality bottoms product for example, a solvent ready to be recycled as in glycol dehydration, amine absorption, extractive distillation or water that has been stripped of contaminants as in Sour Water strippers deodorize edible oils. Used to regenerate solvent for absorption or extractive or azeotropic distillation. Other equipment that is used for stripping include distillation. Section 4.2, gas-liquid separators. Section 5.1 and gas-liquid-liquid separation in flash drum. Section 5.4. The general characteristics of gas-liquid contacting are described in Section 1.6.1. Other operations that use this type of contactor include gas absorption. Section 4.8 reactors. Sections 6.13-6.16 and 6.19 and direct contact heat exchange Sections 3.7-3.9. 

Contactor pressures have little effect on the glycol absorption process as k>ng as the pressures remain below. 3,000 psig. At a constant temperature liic water content of the inlet gas decreases with increasing pressure, thus less water must be removed if the gas is dehydrated at a higher pre.s-sure. In addition, a smaller contactor can be used at high pressure as the actual velocity of the gas is lower, which decreases the required diameicr of the contactor. 

A typical triethylene glycol (TEG) dehydration unit is made up of two main components. The absorber, often known in the industry as the glycol "contactor" and the regenerator, is normally based on direct fired reboiling. The feed gas enters the bottom of the contactor and travels upward. The glycol enters the top of the tower and travels down. Thus dry gas leaves the top of the contactor and rich glycol (containing more water) leaves the bottom. 

The pressure of the rich glycol stream is dropped to near atmospheric and is sent to the regenerator system. Heat is added to the bottom of the column, and the water is driven out of solution to produce the lean glycol stream, which is returned to the contactor. The water exits as the offgas from the top of the regenerator still. In the case of an acid gas dehydration unit, this offgas steam contains H2S and C02 for reasons that will be discussed later, and cannot be vented to the atmosphere. In an acid gas dehydration... 

Dehydrated gas leaving the contactor passes through a gas/glycol exchanger to reduce the reflux (lean-glycol) temperature. In general, the reflux temperature is maintained at 6 to 20°C above the dehydrated gas outlet temperature. 

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