Ceramic-Lined Screw Conveyors for Conveying Abrasive Coal

General Description

Great River Energy is an electric cooperative owned by its 28 members. The cooperative owns and operates coal-fired and other types of power plants to provide electricity to more than 1.7 million customers in the upper Midwest. Coal Creek Station is North Dakota’s largest power plant and features two coal-fired units with a total generation capacity of more than 1,100 megawatts. The power plant is located about 50 miles north of Bismarck, North Dakota, near the city of Underwood. For this project, Great River Energy required ceramic-lined screw conveyors to convey the abrasive lignite coal after sizing and drying. KWS worked with Great River Energy to develop an excellent solution on this project.

Design Parameters

KWS Advantages

Great River Energy and KWS have a long, successful partnership and the Coal Creek Station plant is filled with KWS equipment that has lasted over 10 years. These existing screw conveyors were showing signs of wear due to the abrasiveness of the coal. Great River Energy was depending on KWS’s expertise to solve their wear problems. KWS reviewed the application and provided a long term solution. The conveyor screws were originally hard-surfaced with a cobalt-based material and were actually wearing less than the conveyor troughs. KWS recommended reusing the existing conveyor screws and proposed new troughs with ceramic liners. KWS has extensive experience with ceramic lined screws and troughs for very abrasive applications such as fly ash and dried municipal sludge. In order to save money, the Customer’s existing drives and other components were reused. The result was a set of replacement components that could be installed in mere hours to reduce the downtime of the system. KWS also designed and provided ceramic lined chutes to reduce abrasion and limit the impact from the coal dropping on to the screws and ceramic lined troughs. The ceramic material selected for the application was Alotec-90 made by Dura-Wear. KWS had the experience designing and manufacturing equipment utilizing the Alotec-90 ceramic material that the Customer required. KWS also made sure to properly crate the ceramic-lined troughs to prevent damage during shipment.

Special Features

KWS engineers recreated the system layout using Autodesk Inventor 3D to make sure the new design would fit into the existing constraints. The new conveyors and chute work fit perfectly. KWS designers kept all of Great River Energy’s specific requirements in mind; the approval drawing process required no customer changes. Each conveyor has a carbon steel trough lined with ceramic tiles and the screw is constructed from 304-stainless steel to eliminate the potential for sparking and igniting the coal. KWS had experience installing the ceramic tiles in house, improving the lead time of the project. Outside processing was not required.