Category Archives: Gas Processing

In this tip of the month (TOTM) we will present the compressor calculations of a case study. We will compare the rigorous method results with the values from the short cut methods. The rigorous method is based on an equation of state like the Soave-Redlich-Kwong (SRK) for calculating the required enthalpies and entropies. The enthalpiesContinue Reading

In the March 2011 tip of the month (TOTM) we studied a constant volume translation of liquid density method presented by Peneloux et al. [3] and demonstrated its application for pure components. Considerable improvements were obtained, specifically for the low temperature range (reduced temperature < 0.8), of saturated specific volume (or liquid density) predicted byContinue Reading

As discussed in the May 2011 Tip Of The Month (TOTM), for hydrate inhibition, the most commonly used equilibrium inhibitors used in the upstream and midstream sectors of the oil and gas business are:  monoethylene or diethylene glycol (MEG or DEG) and methanol.  In general, glycols are more commonly used in systems requiring continuous inhibition.Continue Reading

Equations of state (EoS) are used in commercial simulation software for predicting phase behavior and thermodynamic properties. The cubic equations of state (EoS) give relatively accurate results for predicting vapor-liquid equilibria, especially for non-polar or slightly polar systems. Furthermore, these equations can be used to accurately predict vapor densities, enthalpy and entropy. These advantages encourageContinue Reading

BTEX stands for benzene, toluene, ethylbenzene, and xylene, a group of compounds all that also belong to the broader category of Hazardous Air Pollutants (HAPs). Benzene is a known carcinogen, and has also been shown to cause blood disorders and to impact the central nervous system and the reproductive system.  Toluene may affect the reproductive and central nervousContinue Reading

Three methods of preventing hydrate formation in pipelines and processing facilities are commonly used in our industry.  These are: 1)      Maintain the T & P of the system outside of the hydrate formation region. 2)      Dehydrate the gas to remove the water. 3)      Inhibit hydrate formation with chemical inhibitors. Option 3 is commonly used whenContinue Reading

Liquid density is needed for process simulation and equipment design. For example, accurate predictions of liquid density are needed for calculating the pressure drop in piping/pipeline and vessel sizing. Accurate liquid density is also essential for custody transfer. In November 2006, December 2006 and January 2007 tips of the month (TOTM), we presented an overviewContinue Reading

In a past Tip Of The Month (TOTM), we have shown that one of the first issues to be resolved by a facilities engineer working in a gas plant or gas production facility is where the process is operating with respect to the phase diagram.  A general knowledge, if not a detailed knowledge, will allowContinue Reading

Glycol dehydration is the most common dehydration process used to meet pipeline sales specifications and field requirements (gas lift, fuel, etc.). Triethylene glycol (TEG) is the most common glycol used in absorption systems. Chapter 18, Gas Conditioning and Processing [1] presents the process flow diagram and basics of glycol units. A key parameter in sizingContinue Reading

Hydrogen blistering is a type of hydrogen-induced failure produced when hydrogen atoms enter low-strength steels that have macroscopic defects, such as laminations. The defects in the steel (void spaces) provide places for hydrogen atoms to combine, forming gaseous molecular hydrogen (H2) that can build enough pressure to produce blistering. Hydrogen blistering is a problem mainly inContinue Reading