From: John De Armond
X-Source: The Hotrod Mailing list
Date: Nov 1993
Subject: Misc stuff
X-Sequence: 7032

I'm finally back for good from my latest and hopefully last descent
into programming hell.  For those who missed it, I've been off the
last month automating the powerhouse of a large paper mill.
The list has been on automatic.  Yes, I do thank all of you who
DIDN'T comment either to the list or to me about MAKE MONEY FAST!

Anyway, this project had some interesting aspects that I thought
the rest of you power freaks would enjoy.   This project was
the close approximation of installing state of the art engine
management system on a Model T.

The power plant contains 5 steam turbines, the oldest of which was
installed in 1918, the newest in 1952.  The largest turbine
produces 25,000 horsepower (17.5 MWe) from a rotor about 2 feet in
diameter and 8 feet long.  That's power density!  To these generators
were connected state of the art switching and control gear including
Hewlett-packard Unix workstations running Motif as the operator
interface.  Something neat about toggling a 15,000 volt breaker
with a mouse click :-)  The steam to drive these turbines is made
primarily from burning sawdust and waste chemicals from the paper making
process and is almost free.

Another item of interest is the compressed air plant, located in the same
building.  The mill uses about 20,000 SCFM of compressed air at 100 psi.
This is produced by 4 compressors.  Each compressor is essentially a
4 stage, multiply intercooled turbocharger driven by a 1250 hp electric
motor.  There is a gearbox that steps the motor speed up to about
20,000 rpm to drive the 4 rotors of the centrifugal compressors.
Each stage is good for about 25 lbs.  The low pressure stage has
a scroll housing about 2.5 feet in diameter.  The housing runs
about 900 degrees!  The final stage is about the same size as a diesel
truck turbocharger.  There is a large air-to-water intercooler
between the 1st and second stages, between the 3rd and 4th and
after the 4th.  The control system is fairly sophisticated
and includes a vibration monitoring system that shuts the unit down
if any of the rotors start vibrating.  The whole package is about
the size of a pickup truck.  Just what I need for my shop :-)
Just as impressive is the air dryer that dries this air flow to
better than -80 deg F dew point.

This unit kinda illustrates how much power is required to drive
a turbocharger compressor.