Blowdown time in unsteady gas flow
Input(s)
\(\mathrm{V}\): Volume \(\left(\mathrm{ft}^{3}\right)\)
\(\boldsymbol{C}_{\boldsymbol{d}}\): Valve Discharge Coefficient (dimensionless)
\(\boldsymbol{A}_{\boldsymbol{v}}\): Valve Area (in. \({ }^{2}\) )
\(\boldsymbol{\gamma}\): Gas Specific Density (dimensionless)
z: Average Gas Compressibility (dimensionless)
\(\mathrm{T}\): Temperature \((\mathrm{K})\)
\(\boldsymbol{P}_{\boldsymbol{a}}\): Initial Pressure (psi)
\(\boldsymbol{P}_{\boldsymbol{b}}\): Output Pressure (psi)
B: Constant
Output(s)
t: Interstitial Velocity2 \((\mathrm{cm} / \mathrm{s})\)
Formula(s)
\[
t=\left(\frac{B * V}{C_{d} * A_{v}}\right) *\left(\frac{\gamma}{z * T}\right)^{0.5} * \ln \left(\frac{P_{a}}{P_{b}}\right)
\]
Reference(s)
John M. Campbell, Gas Conditioning and Processing, Campbell Petroleum Series, Oklahoma, 1992, Vol. 2, Page 29.