Comparing Alternatives for
Submicron Particulate Control:
Venturi, Wet ESP, CCS

Q. What makes submicron particulate, including diesel soot,
so difficult and costly to control?

A. When drops of water are suspended in a stream of air containing particles,
such as in wet scrubbers or venturis, the air must go around the drops to pass through
the device. This creates streamlines of higher velocity air near each drop. For particles
to be captured, they must push through these streamlines to the surface of the drop.

Particles such as diesel soot, that are under 1 micron, are hardest to control because
they follow the streamlines and avoid contact with the drop. As particle size decreases,
more energy is needed to force contact with the drops. This makes conventional scrubbers
ineffective below a few micons, or pressure drop too high to be practical in a venturi.

ESP technology has different challenges. In general, a dry electrostatic precipitator is inefficient on
submicron particulate such as diesel soot because of inherent equipment limitations on the voltage
and amperage that can be applied, and restrictions on the resistivity and loading density of
the pollutant. Wet ESP can use much higher power levels, at a high energy cost, but is
limited by the difficulty of placing a charge on the astronomical number of submicron particles
even with a light loading concentration. This severely limits the loading concentration.
Among other serious issues for a wet ESP is the intrinsic minimization of corona
charging in the submicron size range due to the physics of corona charging.

The Cloud Chamber Scrubber has overcome these difficulties. CCS charges only the
water drops, not particles. Unlike wet ESP, corona charging is not used. The CCS does
not require the very high voltage and amperage of wet ESP.

The CCS uses billions of water drops to scrub particles such as diesel soot like conventional
scubbers or venturis. But unlike conventional approaches such as Wet ESP that puts a small charge
on the particles, the CCS drops are highly charged. The charge on the drops pulls the particles
through the streamlines into contact with the surface of the drops, thus collecting the particles.
The CCS can handle high load concentrations with negligible influence on capture efficiency.

Q. How does the typical 500 – 3000 watts per 1000 cfm required
by Wet ESP for charging compare with the CCS?

A. The CCS uses less than 10 watts per 1000 cfm for charging. A proprietary and patented
method is used to charge the water droplets. For example, charging droplets to treat 10,000 cfm
draws the same amount of energy as a 100 watt light bulb. The other two sources of electrical
power draw are the I.D. fan (often unnecessary) with a relatively small draw because system
pressure drop is less than 1.5” w.g., and the recirculation pumps with a moderate draw.
The cumulative result is that the CCS system is very energy-efficient compared to other
technologies, particularly Wet ESP.

Q. How is the CCS air pollution control system so different from a wet ESP?

A. Wet ESP tries to charge particles with corona discharge and collect them on a grounded plate
or collector wall. CCS technology does not charge particles – only droplets. Unlike particles,
the droplets are a receptive medium, and the charging mechanism operates under consistent
steady-state conditions. Unlike wet ESP, the CCS offers a high turn-down ratio of 10 to 1 in
changes in the air flow that accommodates process changes or variations, the charging
of the droplets remains constant and predictable.

The CCS will also simultaneously scrub the soluble gases in the emissions stream. This is
particularly important for applications such as diesel soot, which is comingled with numerous
gaseous components. Wet ESP requires the addition of a conventional wet scrubber to
scrub these gases.

Q. What is the best air pollution control system when a plant generates
both submicron particulate such as diesel soot and particulate that is
over 5 microns?

A. The CCS air pollution control system is 99%+ efficient for the collection of all types of
particulate, from 0.1 to 300+ microns. If the emission streams are separate, an excellent option
is a Whirl Wet for the bulk removal of particulate 3+ microns and larger, and a CCS for the
smaller particles. Coarse particles can seriously interfere with the operating of a wet ESP.

Q. Is there an air pollution control system for small particulate that
simultaneously removes fumes and gases?

A. CCS is a unique air pollution control system, in that it removes fumes and gases,
including HCl, HFl, HNO3, H2SO4, SO2, Cl2, NH3 and others simultaneously with all types
of particulate, including diesel soot. See the CCS page for detail. This is important because
now there's a single air pollution control system that can simultaneously handle submicron
particulate and hazardous fumes. A wet ESP would have to be supplemented by some sort
of wet scrubber.

Q. How can one air pollution control system scrub submicron
particulate and fumes?

A. The first stage of a CCS is called the Pre-Conditioning Chamber. It is also the primary
gas scrubbing stage. (See CCS page) In addition, charged droplets of common polarity
instantly disperse in each CVG chamber, providing optimum distribution of billions of fine
droplets. The combined surface area of the drops is extremely large. The gas molecules,
if soluble, will be captured. This large surface area, being charged, is critical for the capture
of fine particles such as diesel soot. This produces the collection of submicron particulate
and the simultaneous scrubbing of gases.

Q. Is there an air pollution control system for small particulate such as
diesel soot, that doesn’t need packing, pads, or filters?

A. The CCS air pollution control system does not use any of these high-maintenance items.
The items you mention are also the source of high pressure drop. Since the charged droplets
are the collectors, there is no need for collector plates, bags, or cartridges. Unlike wet ESP,
there is no complicated array of metal tubes and plate to cake and corrode.

Q. Our application involves hot gases as well as particulate.
Do you have a solution??

A. Yes – the Tri-Mer UltraTemp Hot Gas Filtration System combines
high collection efficiency and operation to 1650°F.

This information is for general information purposes only.
For specific applications, please consult Tri-Mer.

BACK TO CCS HOME PAGE >

HOME l SELECT BY TRADE NAME l SELECT BY NEED l LITERATURE l PRESS RELEASES l CONTACT US

Tri-Mer Corporation
1400 Monroe Street
P.O. Box 730
Owosso, MI  48867; USA
Phone:  (989) 723-7838
Fax:  (989) 723-7844
salesdpt@tri-mer.com

© Copyright 2010 Tri-Mer Corporation
Website designed by Marketing Services Inc.