Steam can account for as much as 40% of a company’s fuel
bill. Here, Grant Bailey of Thermal Energy International,
explains the importance of efficient steam traps

In addition to steam being used to heat
raw material and semi-finished products,
it is also used to evaporate, distil, boil,
brew, react, agitate, clean and sterilise for a
wide range of equipment in a diverse range
of industries. However, it is not free and as
fuel costs increase, so does the cost of
producing steam. Therefore it is essential to:
Determine how efficiently your steam
generation is operating based on steam
output versus fuel input
Determine how much steam is being used
and how much it is costing to generate
Determine the effectiveness of steam traps
and whether they are working efficiently
A steam trap gets rid of condensate, air
and non-condensables as quickly as they
accumulate. In addition, for overall efficiency
and economy, the trap must provide:
Minimal steam loss
Long and dependable service
Corrosion resistance
Air and Non-condensable gas venting
Operation against back pressure
Freedom from dirt problems
Malfunctioning steam traps represent a
significant source of wasted energy and
condensate losses in addition to replacement
and maintenance costs. Depending upon an
individual maintenance routine, around 15%
to 25% of steam traps can be leaking within
any factory or site at any one time resulting
in hundreds of thousands of pounds of
energy being lost annually. This not only
represents a major cost in expensive lost
steam but means additional expenditure in
maintaining, stocking, checking and
replacing mechanical steam traps.

Why do steam traps fail?
Pressure surges due to sudden steam valve
openings and improper piping or trap
misapplication, which in addition to
malfunction can result in water hammer, are
some of the reasons for failure resulting in
either it leaking or the trap failing closed.

When steam traps fail open, and discharge
into condensate return systems, they cause
pressurisation of the condensate lines, which
inhibits trap drainage and often reduces heat
output and production.

Steam traps need to work at optimum
efficiency to minimise the impact on the
environment. For each litre of heavy fuel oil
burned unnecessarily to compensate for a
steam leak, about 3kg of CO2 is emitted to
atmosphere. This equates, over a year, to the
CO2 emissions from 25 cars

The venturi orifice design
According to research carried out by Queen’s
University, Belfast, venturi orifice designed
steam traps, such as those produced by
Thermal Energy International, have been
proven to be the most efficiently designed
steam traps, providing an average reduction
of 11.5% in the portion of the boiler fuel bill
used to generate trapped steam.

While the venturi orifice design retains its
initial efficiency indefinitely, the mechanical
trap, with its moving parts, gradually
deteriorates. With mechanical steam traps,
when heat from steam is lost, vapour
condenses to the bottom of the pipe and
finally makes its way to the mechanical
trap. With the venturi orifice trap, the
difference in density between steam and
condensate and the continuous flow
preferentially discharges the higher density
condensate resulting in less condensed water
on the heat transfer side of the equipment.

This also maintains the steam on the heat
transferring side of the equipment resulting
in better thermal efficiency.

As the venturi orifice steam trap enables
continuous condensate discharge, the trap is
equipped with an orifice, sized to the
application. Therefore the live steam loss is
lower than the loss through a conventional
mechanical trap, even when new. Through
the correct application of venturi throat
design and orifice size, the capacity of the
venturi orifice design can be self-regulated,
dependant on load, and operated from the
maximum running conditions to zero. This
provides increased capacity during start up.

The venturi orifice steam trap effectively
drains condensate from the steam system. As
it has no moving parts to wedge open or fail,
it provides a high degree of reliability and
needs only minimal maintenance. Since the
trap can handle variable loads and
accommodate wide load changes it is suitable
for a wide range of applications. Those
produced by Thermal Energy International,
for example, are usually made from highgrade
corrosion resistant stainless steel and
are performance guaranteed for 10 years,
obviating the need for repair or replacement.