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**Sales Gas Pipeline Part I**

Ref.1: Brill & Beggs, Two Phase Flow in Pipes, 6th Edition, Chapter 1. Ref.2: Menon, Gas Pipeline Hydraulic, Taylor & Francis, 2005, Chapter 2.

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General Flow Equation Energy balance at steady state:

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General Flow Equation Dividing by m and writing in differential form: By using the enthalpy and entropy definition:

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General Flow Equation For irreversible process therefore: For an inclined pipe, therefore: No Work

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General Flow Equation Fanning friction factor ( f ): Wall shear stress: Darcy or Moody friction factor (fm): P P+dP

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**General Flow Equation Pressure gradient in pipe: Usually negligible**

Zero for horizontal pipe

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**Single Phase Gas Flow Reynolds Number**

Reynolds Number in Gas Pipeline:

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**Single Phase Gas Flow Friction Factor**

Laminar Flow (NRe < 2100): Turbulent Flow (NRe > 2100): Moody Diagram Smooth Wall Pipe: Rough Wall Pipe:

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**Single Phase Gas Flow General Equation**

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**Single Phase Gas Flow General Equation**

If T and zg are constant (T=Tav and zg=zav): C2

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**Single Phase Gas Flow General Equation**

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**Single Phase Gas Flow Average Pressure**

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**Single Phase Gas Flow Erosional Velocity**

Higher velocities will cause erosion of the pipe interior over a long period of time. The upper limit of the gas velocity is usually calculated approximately from the following equation: Usually, an acceptable operational velocity is 50% of the above.

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**Single Phase Gas Flow Pipeline Efficiency**

In Practice, even for single-phase gas flow, some water or condensate may be present. Some solids may be also present. Therefore the gas flow rate must be multiply by an efficiency factor (E). A pipeline with E greater than 0.9 is usually considered “clean” .

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**Single Phase Gas Flow Non-Iterative Equations**

Several equations for gas flow have been derived from General Equation. These equations differ only in friction factor relation assumed: Gas Transmission Pipline 1. AGA equation 2. Weymouth equation 3. Panhandle A equation 4. Panhandle B equation Gas Distribution Pipeline 1. IGT equation 2. Spitzglass equation 3. Mueller equation 4. Fritzsche equation

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**Single Phase Gas Flow AGA Equation**

The transmission factor is defined as: First, F is calculated for the fully turbulent zone. Next, F is calculated based on the smooth pipe law. Finally, the smaller of the two values of the transmission factor is used.

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**Single Phase Gas Flow Weymouth Equation**

The Weymouth equation is used for high pressure, high flow rate, and large diameter gas gathering systems. The Weymouth friction factor is:

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**Single Phase Gas Flow Panhandle A Equation**

The Panhandle A Equation was developed for use in large diameter natural gas pipelines, incorporating an efficiency factor for Reynolds numbers in the range of 5 to 11 million. In this equation, the pipe roughness is not used. The Panhandle A friction factor is:

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**Single Phase Gas Flow Panhandle B Equation**

The Panhandle B Equation is most applicable to large diameter, high pressure transmission lines. In fully turbulent flow, it is found to be accurate for values of Reynolds number in the range of 4 to 40 million. The Panhandle B friction factor is:

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**Single Phase Gas Flow Gas Transmission Equations**

A. Comparison of the calculated Output Pressure by AGA, Colebrook, Weymouth and Panhandle equations: Figure 2.5 B. Comparison of the calculated Flow rate by AGA, Colebrook, Weymouth and Panhandle equations: Figure 2.6 We therefore conclude that the most conservative flow equation that predicts the highest pressure drop is the Weymouth equation and the least conservative flow equation is Panhandle A.

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**Single Phase Gas Flow IGT Equation**

The IGT equation proposed by the Institute of Gas Technology is also known as the IGT distribution equation:

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**Single Phase Gas Flow Spitzglass Equation**

The Spitzglass equation originally was used in fuel gas piping calculations. This equation has two version A. Low pressure (less than 1 psig): B. High pressure (more than 1 psig):

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**Single Phase Gas Flow Mueller and Fritzsche Equation**

The Mueller equation is: The Fritzsche formula, developed in Germany in 1908, has found extensive use in compressed air and gas piping:

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**roughness of 700 μ in. for AGA and Colebrook, **

16 in., 100 MMSCFD, 80°F roughness of 700 μ in. for AGA and Colebrook, pipeline efficiency of 0.95 in Panhandle and Weymouth

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**30 in., 100 miles, 80°F, output pressure of 800 psig **

roughness of 700 μ in. for AGA and Colebrook, pipeline efficiency of 0.95 in Panhandle and Weymouth

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