“Upper level building temperatures were as high as 140 degrees.”
No two industrial ventilation systems are designed the same. Too many factors are in play, so we need to ask a lot of up-front questions to operating personnel and plant engineering before we proceed with the design. The following is a synopsis of a project we did near New Castle, DE that was successfully completed because of the important preliminary input from plant personnel.
Excessive room temperatures forced a dry blend manufacturing and processing company to stop production during the hottest time of day. Process equipment included two 50 ft. high spray-dryers, which created large volumes of heated air. Coupled with elevated summertime temperatures, extreme amounts of heated air accumulated in the upper levels of the facility. While regional summertime mean temperatures historically ranged from the mid to high 80s, indoor temperatures were measured in excess of 140o F creating a worker safety risk. In an effort to combat the heat, access hatches on the roof and man-doors at ground level were opened to provide heat relief. This had minimal impact and added a risk of outside contaminants entering the production area.
The 70 foot high facility has seven floors or levels with critical temperatures in the two uppermost levels. As the dryers operate at 450o F, too much cool air over the skin of the equipment had risks, because the potential of condensation on the internal wall of the unit and thus lowers overall production efficiency.
Ventilation System Design
A solution first step was to position supply air intakes in a layout that allowed air to move upward through open service areas and stairwells. Two adjustable outside air intake louvers were installed to allow fresh air into the fourth level of the building. The customer’s stringent product quality control required the incoming air to be filtered. SysTech provided a two-stage filtration system, incorporating a 2’’ MERV 8 pre-filter and a MERV 13 secondary filter. The second step was to install two, roof-mounted up-blast exhaust fans drawing air from the building; providing twelve (12) air changes per hour. Motorized back-draft dampers were used to shut out possible contaminants when the exhaust system was not in use. To allow flexibility when the outside temperatures varied, each fans exhaust flow was modulated with a Variable Frequency Drive.
Installation was included in the project to get the facility up and running ASAP!
The effectiveness of the ventilation system was challenged two weeks after the installation by an extended heat-wave. Outdoor daytime temperatures exceeded 95 oF; however the customer’s facility internal temperature never exceeded 115 oF on the top floors!