Insufficient building air handling unit capacity or inadequate exhaust systems cause condensation inside paper machine rooms leading to operator safety concerns, sheet quality issues and accelerated corrosion of the building structure and machine assets. Light industrial or commercial HVAC units cannot withstand the harsh environment in and around paper machine buildings and are often rendered inoperable within five years of installation. In this ‘Ask the Expert,’ we explore some of the key design elements of paper mill building ventilation equipment with Don Whybro from Enerquin. Don spent the first 30 years of his career as a designer at Enerquin. He has been a Technical Sales Support since 2014.
What are the basic requirements of air handling units?
Fresh outdoor air is filtered, heated and supplied to the building to provide operator comfort and balance the building so that it is not under negative pressure. It consists of a casing, fan, air filters, heating coils, or gas burner.
Why do air handling units require special design requirements when used at paper mills?
Air handling units are often exposed to the elements (outdoors) as well as various airborne chemical compounds. When in a dry state, these compounds pose a minimal risk of corrosion to equipment. However, the potential for corrosion to air handling units increases exponentially when these chemicals are in contact with mist and humidity in the air. These units must provide excellent corrosion resistance and remain watertight. Another important point is that the air handling units should be located so that regular maintenance can be easily performed where possible.
How do you design a system that can withstand this environment and ensure a long lifetime?
Enerquin air handling units utilize modular casings featuring proprietary four-inch, insulated, aluminum encapsulated panels. The aluminum sheets provide excellent corrosion resistance. The panel construction provides a hermetically sealed structure to keep water out. Enerquin’s air handling units use the same panel construction as its high dewpoint hood, used in an even harsher environment. Internal components (filters, coils, burners, etc. must be well supported by independent structure(s) to ensure longevity.
How do you ensure that there will be no condensation inside a machine room?
Once the exhaust system(s) is optimized to provide the appropriate quantity of air changes in various parts of the machine room, an overall air balance calculation is made to determine the total required capacity of the air handling units. When conducting building audits, we often see buildings under a ‘negative’ balance, meaning cold outdoor air enters the building and causes condensation when mixed with hot, humid indoor air. Special attention must be given to the wet end exhaust systems. The wet end is where most humidity is generated in the machine room and needs to be exhausted at a much higher rate than elsewhere. In conjunction with this, the building supply systems should ideally be located to distribute the fresh air from the dry end to the wet end of the paper machine room. This will ensure that the moisture generated from the former and press does not travel throughout the building.
Enerquin is a world leader in major rebuild and greenfield building ventilation projects. Do you have any questions in regards to building ventilation? Contact our experts today.