|
The PERMALIGN® laser system measures
and monitors alignment changes, commonly referred to as "Thermal
Growth", of rotating machinery during operation.
It can measure the absolute move of a machine
or the relative move between coupled machines.It may be used for
permanent monitoring or for just the necessary time to determine
positional change from cold to hot or vice versa.
The user may obtain printout of numerical data,
graphics and plot curves of positional changes over time of any
monitored equipment. Contrasting with other monitoring methods,
PERMALIGN® allows you to determine what movements have
thermal origin and what movements are caused by dynamic influences,
pipe strain or load variations, etc.
PERMALIGN® is the only linearized
laser measuring system with a resolution of one micron throughout
the entire detector range of 0.630". The system permits accurate
measurement of parallel and angular movement at distances of up
to 30 ft. Temperature variations and vibration do not diminish accuracy.
"HOT" ALIGNMENT
CHECKS ONLY TELL HALF THE STORY!
Hot alignment checks are often unsuccessful because of delays in
installing measuring devices on the equipment which has just been
shut down.
 Even
when good planning and organization allowed you to take readings
within minutes of shutdown, these readings only address the so called
"Thermal Growth". Often the effects of thermal growth
on alignment had been calculated fairly accurately and the "hot
alignment" check confirmed them, but still, excessive vibration
persists and continues to be traceable to misalignment.
The problem is that machinery moves during operation
for reasons unrelated to thermal effects.
Dynamic rather than thermally induced movements
may cause machinery to operate misaligned. Since these dynamic effects
disappear before the machinery stops rotating, hot alignment checks
cannot measure them.
The non-thermal moves, both vertical and horizontal,
are often as large or larger than the thermal moves but much more
difficult to calculate. In our experience the dynamic moves are
usually ignored.
These movements can be caused by foundation problems,
by pipe strains and stresses, loose anchor bolts or changes in the
load, etc. Whatever the cause or causes, almost the only way to
determine the movements is continuous computerized monitoring of
the alignment.
When coordinated with records from the control
room it often becomes clear why and how the machinery changed position.
Proper "cold" alignment targeting thus becomes feasible
and significant operational improvements are usually achieved.
Aside from the well known consequences of less
wear on bearings, seals, couplings, etc. it is sometimes possible
to increase the load for the equipment and last but not least, power
consumption will reduce and result in savings which are a multiple
of the cost of the monitoring equipment.
Several monitoring systems have been on
the market for many years using dial indicators or proximity probes,
etc. and now, fully automatic laser systems are available with suitably
large measuring range. PERMALIGN® using the principle
of a prism reflected beam is not affected by temperature variations
and measures accurately even at very high vibration levels.
|
