Page 448 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

426 Major Process Equipment Maintenance and Repair

tended to eliminate errors and omissions in the system checkout prior to
startup.
In review, the expander is protected from unexpected plant problems
by the use of special designs, such as the dust-free seal, the automatic
thrust balance control system, special rotor blading to accept condensa-
tion, rotor and nozzle design to avoid rotor resonance damage, special
instrumentation to protect against freezing, etc. These systems in con-
junction with the protective annunciator system are designed to prevent
premature failure of the expander.
Proper operation and periodic maintenance will ensure a reliable, de-
pendable system.
The need for complete running records must be emphasized. When an
operator understands the readings and knows what to do when a problem
first occurs, he can often make corrections and prevent downtime for the
machine; or assist the manufacturer’s service personnel in making the
necessary analysis and repairs quickly and efficiently.

Installation of Turboexpanders
Arrangements for the installation of turboexpanders must take into ac-
count the specific guidelines issued by a given manufacturer for a given
model or type of machinery. The following generalized installation pro-
cedure is offered as a typical example.

Equipment Foundations
The skid dimensions for mounting the system on its foundation are, or
should always be given on the machinery arrangement drawing.

Handling

A suitable hoist or crane should be provided for installation purposes.
Most models have provisions for the attachment of lifting yokes on the
side of the skid.

Plant Process Connectlons

Connection sizes and locations for plant process inlet and discharge
piping are usually shown on the machinery arrangement drawing.
A 60-mesh cone-type inlet screen and a 3@mesh conetype screen need
to be installed in the expander and compressor inlets of the unit, respec-
tively. The screens must be installed in the process piping with the screen
side upstream. We will discuss cleanliness later, but keep it in mind dur-
ing installation.