Temperature Control of complex
valved piping systems, such as those around pumping
sets and manifolds, can create a problem for the
designer.
All pipe sections are not subjected to the same
flow conditions. Often, only 1 or 2 pumps are operational
whilst the remainder are in the standby/no flow
condition.
A temperature sensor located on a flowing pipe may
de-energise tracing on static lines when heat is
actually needed and vice versa.
Conventional
Control
To correctly control a complex
system from the pipe surface temeperature, each
pipe section requires independant line switching.
This is both expensive and complicated.
A second approach is to operate the heat tracing
permanently, but uncontrolled. The system is designed
to stabilise at a safe temperature, perhaps by means
of self-regulating heating cables. This is excessively
wasteful, as power is applied continuously when
often only a small demand may exist, if at all.
In such a case, line temperatures are often much
higher than required, usually by 30°C, or more.
Powermatch
Control
A Powermatch SELF-REGULATING
SYSTEM CONTROLLER provides the best control for
complex piping systems. The ambient temperature
is monitored and the power output from the constant
wattage heaters is adjusted to precisely match the
heat losses at any given time.
When required, the Powermatch can additionally provide
line control for fine tuning. The line sensor can
be positioned at a point of no flow, eg, a dead
leg or 'dummy' pipe.
Static lines will always receive precisely the heat
needed to maintain the desired temperatures. Any
unnecessary heat received by pipe sections having
flow is safely removed by flowing liquid without
significantly affecting its temperature.
This design
method allows complex piping systems to be controlled
as a single heating circuit in a simple and
effective way.
A single Powermatch
is capable of controlling large areas of process
plant heat tracing, eg. 6 x 60 amp circuits,
thus cabling costs are minimised.
A Powermatched constant wattage
system can be continuously monitoring for correct
heating function and does not suffer from high in-rush
currents on start-up from cold.
