A new digital combustion controller, jointly developed to address energy
efficiency needs emerging as a result of the Climate Change Levy, is set
to become a long term best-seller as organisations ramp up their
investment in energy conservation measures
At least two years before the Climate Change Levy (CCL) became a reality,
boiler controls specialist, Saake had already formed a strategic
partnership with Omron to develop a digital combustion controller, as
defined in the draft CCL documentation. Sales director, Dave Golden
explains that as well as technical and legal issues, market requirements
were a great driver in designing the controller.
When we tried to list out what our customers would want from such a
controller, we concluded that each application was unique and that our
design would have to be flexible enough to address this. So we got Omron
involved and came up with a package design in which you can slot various
control components, such as drives and PLCs, as appropriate.
The most impressive controller installations are those that include an
inverter to control the speed of the forced draft fan, which ultimately
affects the rate of combustion within the boiler. Slowing the fan motor
can save energy in itself, especially when it is sized to produce an
airflow in excess of 40,000m3/h. But often far more substantial is the
saving achieved by optimising the rate of combustion in the boiler to
meet instantaneous demand.
Boilers are usually sized to satisfy peak demand, plus a margin for
error, Winter running, and to accommodate future growth, Mr Golden
explains. A boiler in a hospital or car plant, for example, will need
its maximum capacity very rarely indeed, and could be run at, say, 50%
peak for 70% of its duty cycle - a potentially massive contribution to
carbon emissions reduction and running costs. Even the continuous process
industries, where boiler duty cycles are more constant, can benefit at
least as much and often more from this approach. And when it comes to
inverters for forced ventilation fans, it is a rare one indeed that does
not pay back in well under a year!
The controller
The digital combustion controller can be configured to work in many
different ways. They each have at their heart an Omron PLC, usually quite
a small one, but sometimes one from the top of the range, which can be
programmed to meet the demands of the installation. Typically, there will
be a seven-day duty cycle that changes every month or so as the seasons
progress. To achieve this with the required accuracy, many process
which then optimises boiler performance to achieve the cycle. The PLC
takes information from digital inputs such as damper open/closed as well
as analogue inputs such as temperature and timer information. It
processes these and produces the necessary signals to adjust such items
as fan speed via the inverter.
I reckon the vast majority of boiler users know about the CCL, but quite
an alarming number have yet to address it, observes Mr Golden. Many who
have prepared for it are finding that they are able to reclaim all or
most of the Levy in National Insurance rebates. Those burying their heads
in the sand will lose out! My people are working very hard to make sure
that their clients are up to speed on the CCL. It is not a one-off; it
will be with us for ever, so energy efficiency measures taken now will be
earning their keep every year from now on.
Omron