Dust Collector Screw Conveyor for Calgon Carbon Bay St. Louis, MS

General Description

Calgon Carbon has been manufacturing activated carbon for over 75 years. Activated carbon has many purposes, but it is primarily used as a filter media to remove pollutants, contaminants and other impurities from water and air. At the Mississippi plant, Calgon produces activated carbon from bituminous coal. The end products are used in a variety of applications ranging from wastewater treatment to gas masks used by the US military.

As coal and other bulk materials are conveyed throughout the process, dust is created. Dust collectors are located throughout the plant to pull in contaminated air and filter it through baghouses. A baghouse typically contains many “bags” made of fine mesh cloth which allow air to pass through but not dust particles. Periodically, the baghouse will pulse the bags to shake the dust loose by reversing the flow of air. The dust falls into a screw conveyor located at the bottom of the baghouse which then transports the dust back to the process for reuse. Calgon Carbon contacted KWS because of constant maintenance problems with the baghouse screw conveyors.

Design Parameters

1. Product Type: Carbon / Nuisance Dust
2. Material Density: 40 Lbs. per Cubic Foot
3. Capacity: 8,000 Lbs. per Hour
4. Duty: 24 Hours per Day, 7 Days per Week

KWS Advantages

With more than 45 years of problem solving experience in the bulk material handling industry, KWS has provided solutions to many difficult applications. The baghouse screw conveyor in question was over 33-feet long and had several internal hanger bearings. The hanger bearings were difficult to access and required constant maintenance and replacement. The maintenance costs and downtime were not acceptable. Calgon Carbon asked KWS to provide a solution that would completely remove the hanger bearings. In order to span the full length with a single screw, 12-inch schedule 80 pipe was required to prevent deflection from exceeding the CEMA maximum of 0.250 inches.

To handle the torque and bending loads of the one-piece screw, the drive and end shafts were upsized and higher strength shafting material was used. KWS performed stress calculations on the shafting for the combined loading with a minimum safety factor of 5-to-1. Calgon Carbon can rest assured that the new baghouse screw conveyor supplied by KWS will not fail.

Special Features

Every aspect of the new KWS baghouse screw conveyor was designed to minimize maintenance costs and increase longevity. Pedestal trough ends with heavy-duty spherical pillow block bearings were used on both ends of the screw conveyor to support the heavy screw. KWS split gland seals with graphite rope packing protect the bearings and drive unit from potential contamination and contain pressure within the baghouse.

A Sumitomo foot-mounted in-line drive directly connects with the screw conveyor drive shaft via a Dodge Grid-Lign low speed coupling. The drive is designed to start under a full load of dust in the baghouse. Welded flange trough ends and bolted covers are used to provide a sealed screw conveyor which can maintain the positive and negative pressures of the dust collector baghouse.