Corrugated Container Board

CHALLENGE

Conditions in this paper mill were hot, humid, and miserable. The process equipment would heat the building to incredibly high temperatures. More than 120 F at the mezzanine, with additional elevated temperatures throughout the work line.

The reason for this was obvious; the ventilation system was simply insufficient. Inoperable make-up air units failed to bring any fresh air into the building. That meant that the roof fans, the ones that worked that is, made for a negative pressure environment.

To complicate matters even further, the building is about 100 years old, with a very weird roof. Parts of it were concrete, others were metal. There were even some degraded, rotting support purlins. All of that made any building construction improvements a challenge.

When they decided to replace their roof, however, they decided that they decided that it was also the time to replace their poor ventilation system. Fortunately, they got a recommendation from a sister mill in another state who got their ventilation solution from Moffitt.

DESIGN

The high temperatures and tall roof made this building a prime candidate for natural ventilation. Opening the roof and walls would greatly improve air flow and quality. In addition to removing the hot air, it would also remove the pressurization problems as well.

Moffitt took temperature readings throughout the facility to get a complete picture of the situation. That data was then used to design a computational fluid dynamics (CFD) model. The model illustrated where the hot air was gathering and where intake air was most needed.

The old building structure provided an extra challenge for the design, and ultimately Moffitt revised the design many times to get it to work. Custom louver sizes were needed to best fit the walls. In fact, the Moffitt team inspected the building several times to ensure that the louvers would fit as needed.

The CFD model predicts results at the 5 ft elevation, mezzanine level, and roof. The model illustrates a temperature drop of approximately 13° at the mezzanine. Down from 120°F to 107°F.

SOLUTION

The model determined that a series of louvers would finally bring in the volume of cool, fresh air needed for this building. One hundred fifty-one wall louvers were installed on the north, south and west sides of the building. All at various elevations as the building construction would allow. Finally, twenty-one MatrixVent ventilators were installed in a row on the roof to allow that hot air to escape.

RESULTS

While the real test will come next summer, preliminary results are very close to the original CFD model. Waiting for the upcoming summer to test the official temperature change in the same environment.

Most importantly though, when installation was still underway, the plant staff said they already felt a difference in temperature. Moreover, the installers could feel the hot air rushing out of the building as the MatrixVent ventilators were installed. That meant that air was flowing as it should be and that instead of suffering from negative pressure the building air was now balanced.

No longer need to worry about hot air, humidity, or corrosion. Plus, since the solution is all natural, it performs without any operating and maintenance costs. Possibly best of all, the new solution is more affordable compared to replacing the make-up air units and exhaust fans.