Sales Gas Pipeline Part I

1
Sales Gas PipelinePart I

• Ref.1 Brill Beggs, Two Phase Flow in Pipes,
  6th Edition, 1991. 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

4
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
PdP
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General Flow Equation

• Pressure gradient in pipe

Usually negligible
Zero for horizontal pipe
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Single Phase Gas FlowReynolds Number

• Reynolds Number in Gas Pipeline

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Single Phase Gas FlowFriction Factor

• Laminar Flow (NRe lt 2100)
• Turbulent Flow (NRe gt 2100) Moody Diagram
• Smooth Wall Pipe
• Rough Wall Pipe

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Single Phase Gas FlowGeneral Equation
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Single Phase Gas Flow General Equation

• If T and zg are constant (TTav and zgzav)

C2
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Single Phase Gas Flow General Equation
Le
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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