Aerovent has a concrete” solution for cooling gases in the making of cement

Aerovent has a “concrete” solution for cooling gases in the making of cement
Smith Engineering’s gas cooler heat exchangers provide a safe and effective way to exhaust clean air from cement gases

Cement has a long history that dates back to the Egyptians, who used a form of gypsum with water to create stone blocks for the pyramids. The Romans used limestone, which they crushed and mixed with water to create such marvels as the Coliseum. Since then, cement has evolved throughout the centuries into a mixture of calcium, silicon, iron, and aluminum, known as Portland cement.

Today, about 98% of the cement produced in the United States is Portland cement. Portland cement is produced when all of the material is burned in a kiln, where a chemical transformation occurs creating a redhot ball called a “clinker.” The clinker and the required amount of gypsum are then ground into a powder. The finished cement is stored in silos for packing in paper bags or dispatched in bulk containers.

The goal of the cement plant is to concentrate on making and supplying their customers with a quality product, while protecting the surrounding environment. Smith Engineering, located in Ontario California, along with Aerovent, have helped the cement industry by providing an environmentally safe gas exhaust system for Southdown Corp., a division of Cemex.

Gas Cooling Process
Although Aerovent fans are not used in the process directly related to making cement, we do play a major role in reducing the air pollution emitted from a cement plant. Dust emission from cement kilns can be a serious nuisance. It is widely known that air pollution control is highly regulated and a very important environmental issue. Without proper air pollution control equipment, cement plants would not be able to operateat their current capacity.

Cement kiln dust (CKD) is dust that is generated in the cement kiln and associated equipment. During the burning process, the gas flows entrain a substantial quantity of dust that forms part of the kiln exhaust gases, also known as clinker vent gas. This cement dust cannot be exhausted directly into the atmosphere, so the removal of the dust is crucial to the overall success of each plant.

Various methods are used to capture CKD, such as electrostatic precipitators and bag filters. The bag filter dust collection system is far more economical and depending on the cement plant, far more popular.

“Aerovent fans are used in the exhaust gas coolers, which are part of the air pollution control equipment in a cement plant,” said Charlie Duvall of Sharpe Heating and Ventilating, Aerovent rep located in Whittier, California. “Gas cooler assemblies consist of an air to air heat exchanger, bag collector, and a bank of fans all arranged on a structural steel support system.”

Its purpose is to cool the clinker vent gas down to a temperature that the bag collector can tolerate, which allows cement dust to be filtered out of the clinker vent gas. If clinker vent gas temperatures are too high when passing through the bag collector, the filter media can wear out prematurely and in some cases be damaged or destroyed.

Aerovent fans are an integral component of the gas cooler heat exchangers. When clinker vent gas enters the heat exchanger through a bundle of vertical, parallel tubes, its temperature is approaching 1000°F.

“Aerovent fans blow ambient air across the tubes of the heat exchanger,” said Duvall. “The ambient air absorbs the heat in the vent gas and the velocity of the gas is reduced substantially. The net result is that the clinker vent gases are cooled to about 275°F.”

After exiting the tubes, a portion of the dust particles falls out of the reduced velocity gas stream and into the hopper of the bag filter while the decreased gas volume is conveyed to the dust collector. The resulting clean air can now be exhausted into the atmosphere.

Stacking Aerovent Ring Fans
The Southdown Victorville Cement plant located in Victorville, California recently expanded their facility to handle the increasing need for cement in California.

“Aerovent supplied sixteen 108" diameter, belted ring fans to provide the necessary airflow required to cool the kiln exhaust gases,” said Duvall. “These fans utilize a high efficient M6 blade design and are stacked four high to form a bank of sixteen fans that will move approximately 1,800,00 CFM through the gas cooler heat exchanger.”

The ring fans are cycled on and off based on the gas temperature measured at the leaving side of the heat exchanger. Each fan was equipped with motor side split guards, V-beltdrive guards, and 30 HP motors.

The ring fans were shipped from Aerovent’s Aberdeen, South Dakota, plant to Southdown’s cement factory in California, fully assembled in order to minimize field assembly labor.

Aerovent belted ring fans were selected for this project because of their compact design and quiet operation. The narrow M6 aluminum blade design is very quiet and will not corrode in the harsh environment of a cement plant. In addition, the low vibration levels and heavy gauge construction of the Aerovent fans allowed the customer to maximize his support structure design to incorporate all sixteen fans.

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