JL Clark, headquartered
in Rockford, Illinois, is no ordinary packager. The company,
celebrating its 100 year anniversary in 2004, is recognized around
the world for its award winning metal lithography and exact graphic
reproduction.
Also recognized as a long-time positive corporate influence in
the community, the management of the company was naturally
concerned about the need to comply with US EPA regulations specific
to air quality, specifically Volatile Organic Compound (VOC) and
Hazardous Air Pollutant (HAP, or air toxics) control. With
legislation looming on the horizon, in early 2003 the company began
a thorough review of the pending EPA requirements and a
corresponding search for a company that could provide a system that
would exceed the minimum requirements and do so as cost-effectively
as possible.
This was not the first time that JL Clark had taken steps to
control their emissions. Years earlier, the company had
installed several recuperative thermal oxidizer (RTO) systems that
had satisfied earlier requirements but had, over the years, become
outdated and was a significant drain on the plant's operations
budget. Costs to operate the systems had become a major
component of Clark's annual fuel usage.
It is important to first understand the reasons why the control
of VOCs is important.
What are VOCs?
Organic compounds are compounds that contain carbon and
hydrogen. They occur naturally and can be found in all living
things, but the majority of the organic compounds that we use are
man-made.
Some organic compounds are liquids that require an additional
process like heating or cooling to create vapor. These organics are
stable compounds. Other organic compounds are unstable; an organic
compound is considered volatile if it produces a vapor (a gas) at
room temperature and normal atmospheric pressure. (Think of the
fumes you see on gas pumps without vapor recovery nozzles.) Some of
these vapors are dangerous to humans when inhaled in great
quantities or over a long period of time. Some VOCs interrupt and
destroy natural plant processes. But many of the volatile compounds
have a much more complicated effect: they lead to the formation of
ozone and smog.
Ozone is three oxygen atoms bonded together to form O3. Ozone
occurs naturally, but the introduction of large amounts of VOCs
into our lower atmosphere (the air closest to us) has caused an
unhealthy amount of ozone to be created. Oxides of Nitrogen (Nox) +
VOCs + Sunlight + Combination of complex reactions leads to the
formation of ozone.
In the earth's upper atmosphere, ozone is an important layer
that protects the earth from the sun's ultraviolet rays. But closer
to the earth, ozone is a dangerous compound. It mixes with other
compounds in the air and becomes the main component of smog.
What is oxidation?
At the heart of most pollution control technologies is a concept
learned in early chemistry classes. That concept is oxidation; it
causes compounds (in this case, contaminated air pollutants) to be
broken up and reformed into new (in this case, safe) compounds. Add
the right amount of heat and oxygen to hydrocarbons and oxidation
occurs.
In the thermal oxidation process, the contaminated air is
heated, breaking apart the contaminated compounds. The compounds
will reform naturally, bonding into the harmless compounds of
carbon dioxide and water vapor and releasing energy. Thermal
oxidation requires high temperatures to break apart the compounds.
The large amounts of fuel needed to maintain high temperatures can
be expensive. Different pollution control technologies help reduce
the long-term costs of the equipment.
No matter which oxidation technology is best suited for a
specific application, the "three T's" of oxidation always apply:
Temperature, Time and Turbulence.
Temperature: Based on the VOCs that need to
be destroyed there is a temperature at which the compounds can be
oxidized.
Time: Time relates to how long a compound
needs to be at a certain temperature in order for it to be
oxidized.
Turbulence: Turbulence is a fixed condition
built into the equipment design. It ensures a proper mixture of
VOCs and oxygen for combustion.
A successful technology achieves full oxidation of VOCs by
maintaining the proper mixture of oxygen and contaminants at the
required temperature for a sufficient amount of time.
Recuperative heat exchangers can also be added to thermal and
catalytic oxidizers to recover between 50% and 75% of the heat
released during oxidation. Another system advance is the
Regenerative Oxidizer, which uses multiple ceramic chambers to
recover as much as 90% to 95% of the heat from oxidation.
The secret is to determine which technology works best and most
cost effectively in each application.
The Anguil Solution
After an exhaustive search and thorough review of various
proposals, JL Clark selected Anguil Environmental Systems, Inc. of
Milwaukee, Wisconsin to partner with them to meet their emission
requirements and at the same time reduce their operational
costs. After a kick-off meeting, all parameters were
established and agreed upon and work was begun.
The Anguil solution included a 50,000 SCFM Regenerative Thermal
Oxidizer (RTO) to control the emissions and a Permanent Total
Enclosure (PTE) to capture the emissions from the plant's six
presses. The selection of the RTO technology was important
because it guaranteed the requirement of at least 98% destruction
of the VOCs but also because it was seen as an effective way to
reduce overall plant operation costs because of its inherent lower
operating costs compared with the current VOC control
devices.
How the Regenerative Thermal Oxidizer Works
The Anguil Regenerative Thermal Oxidizer (RTO) destroys air
toxics and VOCs that are discharged in industrial process exhausts.
The Anguil system achieves VOC destruction through the process of
high temperature thermal oxidation, converting the VOCs to carbon
dioxide and water vapor, recycling released energy to reduce
operating costs.
Process gas with VOC contaminants enters the two chamber RTO
through an inlet manifold. A flow control valve directs this gas
into an energy recovery chamber which preheats the process stream.
The process gas and contaminants are progressively heated in the
stoneware bed as they move toward the combustion chamber.
The VOCs are then oxidized, releasing energy in the second
stoneware bed, thereby reducing any auxiliary fuel requirement. The
stoneware bed is heated and the gas is cooled so that the outlet
gas temperature is only slightly higher than the inlet temperature.
The flow control valve switches and alternates the stoneware beds
so each is in inlet and outlet mode. If the process gas contains
enough VOCs, the energy released from their combustion allows
self-sustained operation. For example, at 95% thermal energy
recovery, the outlet temperature may be only 77° F (25° C) higher
than the inlet process gas temperature. PLC-based electronics
automatically control all aspects of the RTO operation from
start-up to shutdown so that minimal operator interface is
required.
The Importance of the Permanent Total Enclosure
PTEs contribute significantly to the reduction in VOCs released
to atmosphere. VOC reduction by a pollution control device only can
affect the VOCs delivered to this device. There can still be
significant fugitive emissions from the processes which need to
accounted for. For example, older processes with capture
efficiencies of 70-85% can result in sufficient emissions that can
cause the facility to reach a facility emission cap even with
pollution control equipment installed. The installation of a
PTE can allow the facility to capture 100% of those process
emissions if certain criteria are reached with the PTE design and
installation. This high capture rate, along with high VOC
destruction rates of new or modified equipment, will significantly
decrease the overall emissions from a facility. This reduction can
allow for additional expansion of production equipment emitting
VOCs without reaching the facility emission limit. The PTE
installation can effectively allow for additional production
capacity.
In 1990, the EPA issued a capture efficiency guideline which
would allow the user the legal presumption of 100% capture
efficiency of VOCs without the requirement for formal capture
testing. Specifically, the following description applies:
If a source is located inside a "total enclosure" and all
emissions are directed to a control device, the requirement to
measure the efficiency of capture is waived and presumed 100%. By
definition then, a "total enclosure" precludes fugitive emissions.
Such an enclosure can be described as a structure that completely
surrounds or enshrouds an affected facility such that all VOC
emissions are contained and directed through an exhaust stack or
into an oven.
The Regulation
On November 13, 2003 the US EPA issued a final rule promulgating
national emission standards for hazardous air pollutants (NESHAP)
for metal can surface coating operations located at major sources
of hazardous air pollutants (HAP). These standards (5700
liters/1,500 gallons of coatings per year) dictate that plants
affected by this derivative of the Clean Air Act must meet HAP
emissions standards reflecting the application of the Maximum
Achievable Control Technology (MACT). The standards outline
various control requirements based on usage of affected compounds
but also provide for emission reduction via a capture system in
conjunction with the pollution control device.
The Result
JL Clark's forward thinking and alliance with Anguil produced a
capture system and pollution control device that not only meets the
since-enacted EPA requirements but exceeds them. The PTE has proven
effective at capturing the emissions from the wet-end coating
operations of the process lines-that exhaust is combined with the
exhaust from the ovens at the inlet of the RTO. This results
in 100% capture efficiency of the VOC/HAP emissions assuring
capture efficiency requirements and eventual destruction. The
high-efficiency RTO itself has proven to be similarly effective,
achieving destruction efficiency in excess of 99% while exceeding
all fuel usage reduction objectives! The combined capture and
destruction efficiency has therefore exceeded 99% for the facility,
minimizing the overall VOC/HAP emissions from the facility and
allowing the facility to meet their emissions cap.
The result is a partnership that further enhances JL Clark's
reputation as an industry and community leader and provides Anguil
with yet another satisfied customer, one of almost 1,500 around the
world.