Problem
A company involved in the automotive aftermarket had a paint
batch mixing and filling operation that used primers and fillers.
They were faced with installing air pollution control equipment to
handle the volatile organic compounds (VOCs) emitted by the
solvents used in their processes. An independent consultant had
determined that total exhaust volume from the facility was 28,000
SCFM of air. The high volume of air resulted in a low concentration
of solvent vapor. This combination of high exhaust volume and low
vapor concentration posed an operating cost problem. In addition,
powdered material dumped into the batch mixers generated dust,
causing potential OSHA violations and hazards to the operators.
Action
After thorough technical evaluation, Anguil Environmental
Systems, Inc. was selected and contracted to solve the VOC problem
and satisfy EPA requirements.
Solution
Anguil analyzed the operation and focused on the composition of
the solvents and the high air volume. Of the solvents used, a small
portion was methylene chloride. Chlorinated compounds are a
potential poison to most catalytic systems and the company's
consultant recommended a thermal incinerator. Anguil recognized
that a less expensive alternative to a thermal unit would be an
Anguil Chloro-Cat capable of processing the chlorinated compounds.
However, Anguil recommended evaluation of alternate compounds to
replace the chlorinated organics. Upon investigation, the company
chemist determined that all of the chlorinated compounds could be
replaced with regular organic solvents.
The high air volume was then addressed. One of Anguil's
strengths is their knowledge in capture hooding and air flow
reduction techniques. The 28,000 SCFM (44,159 Nm3/Hr) of exhaust
was originally recommended based on the assumption that all
thirteen (13) batch mixing devices could potentially be at their
peak mixing and vapor loading capacity simultaneously. Interviewing
the facility manager, it was determined that not all thirteen
mixers were ever loaded simultaneously.
With this information, Anguil developed an air reduction
strategy that greatly reduced capital cost. Anguil designed an air
reduction system after mapping the fugitive VOC's with a portable
FID (Flame Ionizing Detector). This research allowed Anguil
engineers to determine the areas of high VOC concentration and to
subsequently design the innovative capture system.
The company had been using floor sweeps as part of their capture
system that were up to ten (10) feet away from the mixing devices.
The mixing containers had covers that were poor fitting and
extremely heavy. The distance between the floor sweeps and the
mixing devices was the primary cause of floating dust and escaping
vapors. The Anguil solution was to replace the floor sweeps and
mixing tank covers with a close capture hooding system. Anguil
designed a series of aluminum custom fabricated mixing covers with
integral flexible duct connectors to draw the vapors and dust
directly from the mixers. The added benefit of the close capture
hooding was the decrease in air volume necessary to capture the
vapors from the VOC source.
Anguil determined that all of the VOC's from the mixing room
could be adequately captured with 9,000 SCFM (14,194 Nm3/Hr) of air
and that future plans for expansion would not take the exhaust air
volume above 12,000 SCFM (18,925 Nm3/Hr). Rather than focusing on
costly outside make-up air to replace this 9,000 SCFM (14,194
Nm3/Hr) of exhaust, Anguil supplied close capture pick-up hoods in
the mixing room immediately adjacent to the room containing the
fill devices. This air was then transferred or "cascaded" into the
adjacent mixing room, creating makeup air. The VOC concentration of
this makeup air was well below the Threshold Limit Values (TLVs)
but the state of Michigan determined that these VOC's were
fugitives and should be destroyed. The air supply was introduced on
the far side of the mixing room which helped sweep the vapors
across the 120 by 60 foot room towards the pick-up points.
Outside of the building, an Anguil 12,000 SCFM catalytic
oxidizer was supplied and installed on a concrete pad. Prior to
entering the catalytic oxidizer, the entire airstream was fed
through a two chamber dust collector to prevent the particulate and
dust from masking the catalyst or blocking the plate type heat
exchanger. A precious metal platinum catalyst was supplied to
destroy the hexane and toluene organics. Adequate catalyst was
supplied to process 9,000 SCFM (14,194 Nm3/Hr) and as the facility
capacity increased, more catalyst would be added. Due to the well
designed air reduction strategy, Anguil saved the customer tens of
thousands of dollars on their pollution control system while
achieving compliance.