CFM Corporation 2462 - Manual (Page 27)

27
Dutchwest
7001135
In any chemical reaction, including the combustion
process, there are certain conditions which must be
met before the reaction can take place. For example, a
reaction may require a certain temperature, or a certain
concentration of the reactants (the combustion gases
and oxygen), or a certain amount of time. Catalysts,
though not changed themselves during the reaction,
have the ability to act at a molecular level to change
these requirements. In the secondary combustion
chamber of the Dutchwest Convection Heaters, the
catalyst reduces the temperature at which secondary
combustion can start from the 1000 - 1200° F. (540
- 650° C) range to the 500 - 600° F. (260 - 315° C)
range, increasing efficiency, and reducing creosote and
emissions.
Though it is advantageous, the catalytic reaction does
have some limitations of its own. Primary among these
is that the reactants (the gases) come into close physi-
cal contact with the catalyst itself.
To ensure the necessary contact, the catalytic element
in your Dutchwest Convection Heater is composed
of a ceramic base in the shape of a honeycomb. On
each of the honeycomb’s many surfaces a coating of
the catalyst (usually a noble metal such as platinum or
palladium) is applied. The large surface area exposed
in this configuration ensures that the combustion gases
have the greatest opportunity to come in contact with
the catalyst.
Loss of catalytic activity will be apparent in several
ways. First you may notice an increase in fuel con-
sumption. Second, there will be a visible increase
in the rate at which creosote builds up in your chim-
ney connector system. You may also notice a heavy
discharge of smoke from the chimney. There are a
number of catalytic problems which can cause loss of
activity:
Blockage
While the honeycomb pattern ensures good contact, it
also increases the resistance to flow of the combustion
gases, and, because of the many surfaces, provides
more places for creosote and fly ash to deposit. It is
important to follow the operating instructions in order
to minimize these deposits, and to periodically inspect
your catalyst for signs of blockage.
Masking and Poisoning
While the catalyst itself does not enter into the combus-
tion process, it is possible for certain elements, such
as lead and sulfur, to attach to the active sites on the
surface of the honeycomb. Though the catalyst is still
there, it is covered, or masked, by the contaminant, and
cannot function. To avoid this situation, it is important
not to burn anything in your Dutchwest Convection
Heater that is a source of these contaminants. Particu-
larly avoid painted or treated wood, coal, household
trash, colored papers, metal foils, or plastics. Chemical
chimney cleaners may also contain harmful elements.
The safest approach is to burn only untreated, natural
wood.
Flame Impingement
The catalytic element is not designed for exposure to
direct flame. If you continually overfire your Dutchwest
Convection Heater, the chemistry of the catalyst coating
may be altered, inhibiting the combustion process.
Thermal degradation of the ceramic base may also oc-
cur, causing the element to disintegrate. Stay within the
recommended guidelines of the Operation section.
Mechanical Damage
If the element is mishandled, damage may occur.
Always treat the element carefully. Remember the
catalyst is made of a ceramic material; treat it as you
would fine china. Hairline cracks will not affect the
performance of the catalyst, as long as the steel sleeve
holds the element in the proper position.
Peeling
Peeling of the surface coat may occur if the catalytic
element is frequently subjected to excessive tempera-
tures. Follow the operating instructions carefully to
avoid this type of damage.
Every Dutchwest product is equipped with either a
Corning “Long-Life”
® or a Technical Glass Products
“Honeycomb” ® . The products are equivalent. If for any
reason you must ship your catalytic element, remem-
ber its fragile nature. Place the element in a plastic
bag, and package it with a generous amount of shock
absorbing material.
Catalytic Combustor