Written on August 1, 2009 at 10:31 pm, by Dr. Mahmood Moshfeghian
During the life cycle of a crude oil pipeline the properties of transported oil change, because in gathering systems the produced oils come from different wells. New wells may be added or some wells may go out of production for maintenance and repair. Production rates during the life of wells vary, too. In addition theContinue Reading
Written on July 1, 2009 at 10:23 pm, by Dr. Mahmood Moshfeghian
The change in enthalpy for a fluid where no phase change occurs between Points (1) and (2) can be expressed as: (1) The second term on the right hand side of this equation is generally not convenient to solve manually. However, it is trivial or zero for the following cases: (1) ideal gases, (2) constantContinue Reading
Written on May 1, 2009 at 10:07 pm, by Joe Honeywell
One of the most important physical properties of a gas is the ratio of specific heats. It is used in the design and evaluation of many processes. For compressors, it is used in the design of components and determination of the overall performance of the machine. Engineers are frequently asked to evaluate a compressor performanceContinue Reading
Written on April 1, 2009 at 9:51 pm, by Dr. Mahmood Moshfeghian
The formation of hydrates in processing facilities and pipelines has been a problem to the natural gas industry. Whether the problem occurs in transportation or processing, hydrate formation can cause shutdowns and even destruction of valuable equipment. Because of these devastating and often costly consequences of hydrate formation, methods have been applied to prevent hydrateContinue Reading
Written on March 1, 2009 at 9:23 pm, by Dr. Mahmood Moshfeghian
In the February 2007 tip of the month (TOTM), Joe Honeywell [1] presented a procedure for calculating fluid pressure drop for liquid in a piping system due to friction. Continuing Honeywell’s TOTM, we will outline procedures for calculation of friction losses in oil and gas pipelines. From an engineer’s point of view the question may arise “howContinue Reading
Written on January 1, 2009 at 9:13 pm, by Kindra Snow-McGregor
In this tip of the month, we will discuss how miscalculations and incorrect analysis of potential process upsets can affect process safety. There are many aspects in facility design engineering and process safety engineering that should be considered when designing a new facility or debottlenecking an existing one. During these times of compressed schedules andContinue Reading
Written on November 1, 2008 at 8:50 pm, by Dr. Mahmood Moshfeghian
In this tip of the month (TOTM) we will present the results of several case studies showing the effect of gas molecular weight on the performance and efficiencies of centrifugal compressors. We have considered several “what if” scenarios such as variation of compressor speed as a function of molecular weight, while maintaining the same suctionContinue Reading
Written on October 1, 2008 at 8:25 pm, by Dr. Mahmood Moshfeghian
Gas density estimates are of fundamental importance for process simulation, equipment design, and process safety engineering. In the previous Tip of the Month (TOTM), two shortcut methods for predicting sour and acid gas density were evaluated. We showed that Katz correlation gives accurate results for lean sweet gases and it is the most accurate inContinue Reading
Written on September 1, 2008 at 8:10 pm, by Dr. Mahmood Moshfeghian
Gas density is needed for process simulation and equipment design. For example, accurate predictions of gas density are needed for calculation of pressure drop in piping/pipeline and for vessel sizing. Accurate gas density is also essential for custody transfer metering. Gas density, , is calculated by: (1) Where: &Gas density, kg/m3 (lbm/ft3) Absolute temperature, KContinue Reading
Written on August 1, 2008 at 5:56 pm, by Dr. Mahmood Moshfeghian
There are a few computer tools designed specifically for modeling and analysis of complex multiphase systems such as PipePhase, PipeSim, OLGA, and etc [1]. Modeling and simulation of multiphase system, even under steady-state condition, is complex. In the June Tip of the Month (TOTM), we illustrated how the process simulation programs can be used toContinue Reading
