A Rock Solid Relationship
Blue Circle Cement and Aerovent Fans
Cement. We drive on it, walk on it and build with it. Because it makes up the infrastructure of our cities, we depend on it to stand up to the elements. But if cement isn’t manufactured properly, it will crumble under stress.
Manufacturing is key to making the highest quality cement, and Aerovent plays an important role in that process. Aerovent supplies fans used in the rotary kilns at Blue Circle Cement, a subsidiary of Lafarge Group, in Ravena, New York and Harleysville, South Carolina.
Cooling the kiln; keeping the “heat” out of the “hot spots”
How do fans factor into cement manufacturing? It all comes down to staying cool. Let’s start with the rotary kiln.
The rotary kiln is the cornerstone of the cement production system; it’s where raw materials are transformed into cement. Raw materials are fed into the upper end of a rotating, tilted, cylindrical kiln. The mixture passes through the kiln at a rate controlled by the slope and rotational speed of the kiln. Burning fuel is forced into the lower end of the kiln.
Inside the kiln, the raw materials reach temperatures of 2,600°F to 3,000°F. A series of chemical reactions takes place causing the materials to fuse and create cement clinkers – grayish-black pellets about the size of marbles. The clinkers are discharged red-hot from the lower end of the kiln and transferred to coolers. Cooled clinkers are combined with gypsum, ground into a fine powder and packaged as cement.
The rotary kilns are lined with a refractory lining to keep the heat inside. Sometimes these kilns can retain too much heat and develop hot spots that can damage the lining. That’s where Aerovent fans come in. The fans are strategically placed below potential hot spots on the kilns at approximately a 30-degree angle to help cool those locations.
Cementing the deal: A tale of two kilns
In late 1999, Blue Circle Cement contacted Rick King of Richard E. King, Inc., an Aerovent rep, about a project for its Ravena location. “With the help of Jim Smith and Dan Wieting at Aerovent, we explained how to best arrange the fans and distribute air over their cement kiln,” said Rick. “It was our ability to work through airflow scale-up distribution options that helped Aerovent secure the job.”
The airflow scale-up distribution is a calculation for selecting the proper fans for an application. In the case of Blue Circle Cement, several factors were considered to select the right fans such as kiln diameter, surface temperature, amount of airflow required, and CFM per square foot.
In 2000, Blue Circle Cement placed an order for 20, 48-inch Type B, Direct Drive Vaneaxial fans from Aerovent for applications on kiln #1 of their operation. Six months later, they purchased 20 additional fans for kiln #2. Based on King and Aerovent’s consultation, each fan was fitted with a nozzle configuration (see photo at right) created specifically for the job. The 48" fans were supplied with 15 hp, 1200 RPM motors and a one piece cast solid propeller surrounded by a heavy gauge welded housing.
“These fans used a modified construction that allowed them to be setup for the job they needed to do,” said Dan Wieting, Sales Application Engineer for Aerovent. “This type of design/engineering is what sets Aerovent ahead of the pack.
In January 2001, Rick received another call from Blue Circle Cement’s engineering group in Harleysville. “They were looking for information about the fan selection for the Ravena project,” Rick said. “I made some comparisons of Harleysville and Ravena’s kilns and suggested they would get a comparable performance with 12 fans per kiln, rather than the 20 used on the last project” Blue Circle Cement in Harleysville ordered 11 fans in 2001. And in June of 2001, Blue Circle ordered more fans to be used as spare units.
A delicate balance
Aerovent realizes that every once in a while a fan is put into an unknown situation that can create a minor obstacle. In this case it was the way the props were balanced." The standard method of adding washers to a bolt proved to be a cement dust trap,” Rick explained. “It caused an imbalance in an area of the kiln where the ambient air is relatively dusty. Aerovent was right on top of the situation and acted fast in solving the issue by changing the balancing method for the fans in that area, the problem was immediately corrected.”
No question, it’s been a partnership made in (rock) heaven. Blue Circle Cement was pleased with the entire project, and has enjoyed working with both Richard E. King, Inc. and Aerovent.
“Aerovent has been a valued manufacturer for the last 22 years,” added Rick. “At Richard E. King, we’re proud of the Aerovent reputation. It has a tremendous influence in discussions with customers like Blue Circle Cement, and we’re delighted we can meet their needs.”