history
Tekra Corporation has always had an eye on their energy
conservation. They are a custom coater of plastic films in
Wisconsin where state regulations require over 98% of the Volatile
Organic Compounds (VOCs) emitted from their process be destroyed in
an oxidizer system. While considering their first oxidizer system,
Tekra's Engineers did their homework and invested in an early model
Regenerative Thermal Oxidizer (RTO). While at the time RTOs were
not the cheapest oxidizer option capital-wise, Tekra knew that
long-term, an RTO was their best choice for reliable air pollution
control, lower operating costs and a smaller carbon footprint. "We
have always tried to be a Green Company" said Zachary Gernetz,
Project Engineer for Tekra.
In 2003, it was time for Tekra to replace their aging RTO system
and they turned to Anguil Environmental Systems, Inc. out of
Milwaukee, WI. The equipment of choice was again an RTO,
although Anguil's RTO had significant advantages over the previous
model including: 95% TER (Thermal Energy Recovery), lower
horsepower, lower operating temperatures and better options for
turndown and idle modes.
"Tekra went so far as to have us install a small odometer-style
meter right on the front of the control panel for the Anguil RTO
showing exactly how many BTUs they were saving over their previous
unit." says Greg Blando, Service Manager for Anguil.
ceramic media retrofit
Tekra's focus on achieving better
energy efficiency did not end there. With a new nationwide
focus on green business practices and energy costs on the rise,
they again challenged Anguil to perform even better in 2009. Anguil
studied the temperature charts of the RTO system and took air
samples during peak VOC loading production runs and determined that
the 95% TER of the system could be pushed closer to 97% without
creating any adverse high-temperature conditions in the RTO.
Thermal Efficiency of an RTO relates to the ceramic media inside of
this type of oxidizer which captures, and then utilizes energy from
combustion to pre-heat the incoming, untreated airstream.
"A 2% improvement in TER may not sound
all that impressive," says Mike Scholz, Project Engineer for
Anguil. "But most RTOs out there today were designed to achieve
about 95% TER. The natural gas required by those systems is
directly tied to that 5% of energy lost. Getting back 2 of the
'lost 5%' is actually a 40% reduction in energy lost. In practical
terms, that 2% improvement in TER can translate into 40% less on
your RTO natural gas bill." In addition, the enhanced performance
at Tekra put their oxidizer into a self-sustaining mode more often,
meaning the fuel value in the VOC-laden exhaust gases are enough to
operate the RTO and no auxiliary fuel is needed - hence fewer
greenhouse gases emitted.
project payback
Because of advances in RTO ceramic
heat recovery media, Anguil is routinely able to provide RTO
operators like Tekra with a performance upgrade by either adding to
the top of existing media beds or at times replacing the top
several layers of existing beds with new extruded ceramic media
blocks. "With this type of project, payback is king," comments Lee
Kottke - a manufacturer's rep for Anguil closely involved in the
Tekra relationship. "That's why it is exciting that Anguil can
achieve this level of success with only partial media change-outs.
That keeps the project cost down and payback periods very
reasonable."
There are other possible effects on project payback to consider.
Deeper media beds may require the relocation of chamber
instrumentation - like thermocouples. Also, higher efficiency media
styles can come with increased backpressure and electrical
horsepower cost. Often, however - as in the case of Tekra's RTO -
the electrical penalty is minor compared to the natural gas
savings.
Gernetz said that with two coaters, running a variety of coating
weights and line speeds, it is difficult to get an exact dollar
savings. However, prior to the media replacement their RTO often
required natural gas to maintain temperature when only treating the
exhausts from one coating line. Post retrofit, "the RTO rarely
requires natural gas even when only one coater is operating and
never when both are on." says Gernetz. Zach added, "Jobs that were
never self-sustaining before are now, so I know that the media
retrofit is saving us money." He estimates a 2 year payback for
this retrofit.
Considering some enhancements to your RTO? Think about
this:
- Up until recently, most RTOs were designed with 95% Thermal
Energy Recovery (TER%) or less.
- Rule of Thumb for a self-check: If the average RTO outlet
temperature is more than 100°F higher than the RTO inlet
temperature your actual TER% is probably less than 95%.
- Even a small increase in TER% can have a dramatic effect on
RTO fuel usage. In some cases, a bump in TER% could eliminate RTO
fuel use entirely.
- Advances in ceramic media have allowed Anguil to improve
TER% in RTOs by only replacing a portion of the existing ceramic
media beds, improving payback periods.
- Anguil has performed this retrofit on numerous RTOs,
regardless of original manufacturer, and we offer free savings
analysis for those interested.
According to Chris Anguil, President of Anguil Environmental
Systems, Inc - "When I reflect on the relationship between Anguil
and Tekra, it strikes me how RTOs - while such a huge leap forward
in energy efficiency over previous oxidizer styles - are continuing
to evolve. Advances in media and advances in controls mean there is
still room for efficiency improvements on any RTO system out there
- regardless of age. Anyone owning an RTO should follow Tekra's
lead and continue to ask if they can do even better energy
efficiency-wise. We applaud Tekra's commitment to environmental
compliance and energy efficiency and thank them for challenging us
with this opportunity."