Terminology and a Profile from a Pulp Mill Project
Procedure- Step #1 Ceramic Insulation Coatings applied to 20 mill thickness to the 52 ft.dia x 70 ft. high stainless steel white liquor tank, to protect substrates from chloride attack, associated with the conventional insulation system to be install over the Ceramic Insulation Coatings, also reduced the surface temperature of the stainless steel tank sufficient to accommodate step #2 procedure of installing high temp. polyurethane foam insulation. In addition the Ceramic Insulation Coatings provided an impermeable barrier as protection against corrosion attack, due to moisture migration through the high temp. polyurethane foam insulation should it possibly occur.
Procedure- Step #2 High temp. polyurethane foam insulation was installed over the Ceramic Insulation Coatings to provide insulated R-Value to deal with thermal conduction heat loss. The polyurethane foam was then protected with a topcoat of spray-applied elastomeric to guard against UV attack and provide a weatherproofing envelope.
Testimonial on the Procedures used
One year after installation :
The exterior coating system that your company used on our white liquor storage tank appears to be holding up very well. I cannot comment on what is going on under the coating as I have not disturbed it. I can say that it looks as it did immediately after the installation.
Mechanical Engineer - Kiln & Recaust
Canfor Northwood Pulp Mill
Dry Film Thickness:
Thickness of an applied coating when dry; expressed in the industrial maintenance coatings handbook in MILS or MICRONS.
The spreading rate of a coating without taking into consideration wastage or loss. Calculate the average waste factor using a rate of 10 to 15%.
Solids by Volume:
The volume the nonvolatile portion of a coating composition divided by the total volume.
(DFT) = wet film thickness x per cent
Solids by volume (100 percent by volume at 1 mil thickness is equal to 1604 sq. ft.)
Modes of Energy Transfer
Heat flow through matter resulting from physical contact or the transmission of heat by molecular motion.
Thermal energy moving through a fluid. Air is considered a fluid.
Electromagnetic energy radiated by liquids, solids, and gases. Some examples are heat coming off metal such as a wood stove, commercial metal containers, ductwork and other metal surfaces. The sun is the most powerful radiant energy source we have on earth.
Radiant Heat vs. Conductive Heat Barriers
An effective conductive heat barrier reduces heat transfer and provides thermal resistance (R-Value). The most significant drawback to conventional mass insulation systems relates to thickness; the thicker, the better. Characteristics of degradation and loss of R-Value due to aging or condensation decrease the effectiveness of conventional insulation systems.
Additional Insulation Value
Ceramic insulation coatings are applied at dry film thickness (DFT 11 to 17 MILS). Additional thickness does not increase performance. The principle of solar radiation and increased performance is related to solar reflectivity and thermal emisstivity, not thickness. If the substrate surface is in a high traffic area, and personnel protection is a consideration, additional coats will reduce surface temperature to acceptable levels.