Problem
The world's largest button manufacturer needed a pollution
control system that would destroy styrene emissions from a variety
of plant processes. The plant was proactively seeking a
cost-effective air pollution control solution to preempt future
regulatory action. The main concern of the customer was the high
operating cost of an emission control system.
Action
After thorough evaluation of several possible technology
solutions, the company selected Anguil Environmental Systems, Inc.
(Anguil) to process their styrene emissions. Anguil recommended a
unique solution, a Rotor Concentrator coupled with a Catalytic
Oxidizer, to destroy the VOC concentration. A key factor was
Anguil's ability to lower the volume of air that needed to be
treated by achieving a 10 to 1 flow rate reduction with the Rotor
Concentrator. Anguil provided the customer with a static pilot test
to prove the effectiveness of the concentrator wheel on styrene.
The successful results from the static test ensured the customer's
confidence in the new application of the concentrator technology to
control styrene emissions.
Solution
Three main considerations guided the design of this solution:
the need for an emission control system with low operating costs;
the control of the high volume, low volatile organic compound (VOC)
concentration of the process air stream; and the unique
characteristics of styrene.
Many of the processes that emit styrene - such as boat building and
FRP - have high airflows with low VOC and styrene concentrations.
Button manufacturing presents a similar problem but on a slightly
smaller scale; the plant's airflows were approximately 15,000 SCFM
with styrene concentrations ranging from 50-200 ppmv. The customer
considered a regenerative thermal oxidizer (RTO) and a
biofiltration system as other possible solutions. While effective
in destroying styrene, both of these would have been very expensive
solutions because higher air flows result in higher costs for
treatment technologies. The operating costs of the RTO and the
biofilter were much higher than Anguil's solution because these
systems had to treat the entire 15,000 SCFM of process air.
Anguil's solution, a rotor concentrator coupled with a catalytic
oxidizer, reduced the process air that needed to be treated by a
factor of 10. The high volume airstream, approximately 15,000 SCFM
with 50 - 200 ppmv of VOC, is passed through the rotor concentrator
wheel where the VOCs and styrene are adsorbed in the bed, purifying
the high volume air. This high volume air is then exhausted to
atmosphere. The concentrator wheel rotates continuously,
transporting adsorbed VOCs into a desorption section where they are
desorbed from the adsorptive media with a low volume heated
airstream. After being desorbed from the wheel, the air volume has
been reduced from 15,000 SCFM to about 1500 SCFM and the VOC
concentration of the air stream is increased to about 500- 2000
ppmv. This low volume, high VOC-laden air is then processed by the
oxidizer. By isolating and treating the lower air volume, Anguil is
able to provide a system with far lower operating costs than other
emission control systems.
Anguil was able to further reduce the operating cost of the system
by utilizing a catalytic oxidizer to destroy the concentrated,
contaminated air stream. Anguil's experience with styrene emissions
has demonstrated the easily-oxidizable nature of styrene in the
presence of catalyst. Catalytic oxidation systems typically achieve
greater than 99% destruction of styrene with relatively low
temperature requirements. An Anguil Catalytic Recuperative Oxidizer
designed for 1,500 SCFM was installed to process the VOC-laden
airstream with minimal auxiliary fuel consumption.
The final design consideration was to address the unique
characteristics of the styrene emissions. Because the rotor
concentrator wheel is a relatively new technology, there are only a
few examples of concentrator wheel technology in the styrene
industry. The customer was concerned with the possibility of
styrene polymerization on the wheel and subsequent system failure.
Anguil had performed extensive tests to establish that certain
zeolite formulations function better than others in the presence of
styrene and eliminate the possibility of polymerization. However,
Anguil went the next step in order to relieve the customer's
concerns. Working closely with one of their technology partners,
the Engelhard Corporation, Anguil ran several static (live) pilot
tests to prove the effectiveness and reliability of the
concentrator/oxidizer technology. This testing process convinced
the customer to move ahead with the Anguil solution.
Another benefit to the customer of the rotor concentrator/oxidizer
system was low maintenance cost. The zeolite material has an
expected life of 10 years under continuous operation. The easy
regeneration and durability of zeolite provides considerable
savings over the constant maintenance and replacement required of
carbon beds. Additional maintenance savings come from the durable
design of the rotor concentrator. The concentrator wheel is rotated
with a simple motor and belt drive -- reliable components that last
at least five years and require minimal maintenance.
In order to expedite installation, Anguil assembled the entire
system in its manufacturing facility, allowing for customer review
and inspection prior to shipment. The system was then re-erected in
the field and integrated into the customer's process. Anguil's
combination of proven experience and technologically advanced air
pollution control products have led to another satisfied Anguil
customer.