  Pipe flow models are developed with a focus on their eventual use for
feedback control design at the process control level, as opposed to the unit
level, in gas processing facilities. Accordingly, linearized facility-scale
models are generated to describe pressures, mass flows and temperatures based
on sets of nonlinear partial differential equations from fluid dynamics and
thermodynamics together with constraints associated with their interconnection.
As part of the treatment, the divergence of these simplified models from
physics is assessed, since robustness to these errors will be an objective for
the eventual control system. The approach commences with a thorough analysis of
pipe flow models and then proceeds to study their automated interconnection
into network models, which subsume the algebraic constraints of bond graph or
standard fluid modeling. The models are validated and their errors quantified
by referring them to operational data from a commercial gas compressor test
facility. For linear time-invariant models, the interconnection method to
generate network models is shown to coincide with automation of Mason's Gain
{Formula}. These pipe network models based on engineering data are the first
part of the development of general facility process control tools.
