Cloud Chamber Scrubber Case Studies
Case Study #2:
Glass Fiber Manufacturing
Mat Glass Forming Lines.
Applications where conventional equipment struggles to
attain only marginal efficiency provides an opportunity for the Cloud Chamber Scrubber (CCS)
to showcase its unique capabilities. Glass fiber manufacturing is a typical example. This is not
to be confused with fiber optics manufacture, the subject of a different case study.
There have been two piloting studies on the glass fiber, one successful in 2005 and the other
unsuccessful in 2008. These were done at two different companies on similar but not identical
glass forming lines. The difference between the two sets of results illustrates, we believe, an
important feature of the Cloud Chamber Scrubber technology. This case study examines
The CCS is a three-stage process: a Pre-Conditioning Chamber (PCC) followed by two
chambers called Cloud Generation Vessels (CGV) that create charged droplets. The PCC
is a modified spray tower operated under special conditions. The PCC serves several functions:
it removes large particles through impaction with ordinary uncharged water drops; and it is the
primary site of scrubbing for acid gases and other soluble gases in the flow stream. However,
the PCC also is very important for another reason. By cooling of the gas and providing conditions
of high relatively humidity, the PCC allows ultrafine particles (under 0.1 micron) to grow through
agglomeration and coagulation. This phenomenon is well-known. The fundamental research
was done many decades ago and named the Kelvin-Kohler effect in the scientific literature.
The Kelvin-Kohler effect is dependent on a number of variables. Among the critical variables
is the initial density of particles that can act as nuclei for condensation of water vapor. If the
number density of particles is too low, the effect is minimal or even fails to go forward. When
the number density passes a critical threshold, and the other variables are at suitable values,
then the effect is robust. However, the particles do not continue to grow in size indefinitely.
Other forces start to act, and the average grown particle stays in the 0.2 – 0.3 particle range.
This is ideal for the charged water droplets of the CGVs to remove. This particle size is still
quite small, however, and poses a serious challenge for other fine particulate removal
technologies. The particulate is also a wet stream that creates yet other problems for
conventional equipment. [ More detail about the operation of the CCS is found at
www.tri-mer.com/wet_scrubber.html and a brochure is available for download.]
Our tentative conclusion regarding the difference between our successful and unsuccessful
glass fiber tests is centered on the initial ultrafine particle density at the inlet to the CCS:
the unsuccessful test had less than one-third of the density of the successful test.
Consequently, we did not achieve a high percentage removal rate which is common
to other CCS applications in glass. (See other Case Studies for details.)
The first tests, however, done at a different location and with a different fiber-producing
company, remains valid. Inlet conditions are indicated in Graphic 1 (below). As can be seen,
the inlet loadings of the successful test were already very low.
The history of the initial tests remains instructive. Following other successful applications in
the glass industry, a pilot study to evaluate the performance of a Cloud Chamber Scrubber
(CCS) system was completed in the fall of 2005. The purpose of the study was to evaluate the
ability of the CCS to treat emissions from the exhaust of two different types of fiberglass forming
lines for particulates. One line utilized a formaldehyde based phenolic resin binder, while the
other produced wool for blowing applications and did not use any type of binder. In addition to
particulate removal, the CCS was evaluated for its ability to manage the large fibers that are
often entrained in this exhaust stream. The concern was that these fibers would cause
unacceptable maintenance issues in the recirculation system of the scrubber such as
clogging of the spray nozzles and mist eliminators. Data from the pilot study has been
used to develop a design anticipated for use on several large industrial installations.
A third-party testing company was retained by the customer to source test the inlet and
outlet of the CCS using EPA Method 5/202 for particulates and condensables. The
proprietary results confirmed to the glass company host that the CCS had superior
performance over the conventional equipment currently in use and the pilot tests were
deemed a very valuable exercise in preparation for new regulations anticipated at existing
locations and for new facilities in planning. Expansion at the test site did not take place in
2006 as anticipated so that a commercial-scale CCS was not installed. Tri-Mer has been
contacted by the company for a possible 2010 installation.
Tests conducted independently by Tri-Mer on the pilot unit showed that the CCS could
remove filterable and condensable particulates to concentrations less than 0.002 grains/dcf.
The CCS easily captures particles larger than 1 micron. The challenge is with the submicron
particulate that is the main source of opacity in the stack and the health hazard that is being
mitigated. Using a Dekati Mass Monitor (DMM 450) to analyze the submicron fraction of the
emission yielded the impressive results in Graphic 1.
Glass Fiber Forming – Removal of Submicron Fraction (DMM Data)
Graphic 1. Inlet and outlet results for just the submicron fraction of the fiberglass forming line emissions.
Results are for total particulate plus condensables .
These levels of performance are well in excess of those currently required and even those
anticipated as regulations for PM 2.5 continue to become more restrictive.
Consistent with other glass industry applications, the evaluations also showed that the CCS
system could operate on a continuous basis with no reductions in performance or impacts to
the system that might be cause for concern in regards to long term commercial operations.
Specifically the issue regarding the management of large fibrous particulates was shown to
be acceptable in terms of long term maintenance and without negative effect on capture of
the submicron PM and condensables.
Interest has been expressed in the particle size distribution as measured by the sophisticated
Dekati Mass Monitor (DMM), since this information is rarely available. Tri-Mer Corporation
owns one of the few industrial scale DMMs in the United States. The particle distribution
below 1.5 microns is shown for the no-binder cases. Most were distributed around the 0.1
micron size range. See Graphic 2 below.
Glass Fiber Inlet – Outlet Particle Distribution
Glass Fiber CCS Pilot Test; No Binder – DMM Measurements
Relative Load of Total Particulates < 1.5 Microns
Graphic 2. Size distribution of particles at inlet and outlet of the CCS. Centered at 0.1 micron,
this graph illustrates the effectiveness of the CCS in capturing submicron particles,
even those smaller than 0.1 micron.
We Can Help You with Some Guidelines.
For more information contact:
Kevin Moss (801) 294-5422
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