Relocating the South No. 6 Tower
at the
Labadie Plant

Client Union Electric Company End of Bottom Road Labadie, Missouri 63055 Completion Date December, 1996

Project Description
The 4x600 MW Labadie Plant has three stacks. Units No. 1 & 2 each have an individual stack located directly behind each unit. Units No. 3 & 4 have a common stack, located between the units. The two flues are placed within an outer shell. The coal reclaim conveyors are routed through the lower portion of the shell. The conveyor take-up for tensioning these belts was attached to the outer casing of the Unit No. 3-4 stack.

In response to the lower sulfur requirements of Clean Air Act Amendments, plant fuel was switched to PRB coal in 1991. PRB coal is dustier and more reactive than Illinois coal. As a result, a dust problem became apparent at the Unit 3-4 stack take-up location. Belt flexing at the take-up pulleys released fine dust particles, which became airborne. They were then swept into the interior of the common stack shell by the natural chimney draft. The large coal particles fell into a pile, which accumulated at the base of the shell. The coal fines drifted upward to accumulate at inaccessible locations within the common stack shell. There they caused fires and created an explosive hazard.

The belts were experiencing tracking problems. Coal was accumulating on the take-up bend pulleys. During the winter, this coal froze to the pulleys increasing belt misalignment. The conveyors are relatively long, approximately 900 feet. They extend from grade to the surge bin above the plant silos. The misalignment problem "chewed-up" the edges of the belts, damaging approximately two-thirds (2/3) of a mile length of belt for the two conveyors.

To correct these problems, Union Electric engaged Energy Associates to examine the possibility of relocating the take-up. Energy Associates investigated alternatives and recommended a horizontal, gravity arrangement. The take-up was located at grade where it is accessible. Features to improve maintenance and clean-up were incorporated into the design. Energy Associates prepared the detail design drawings, material purchase requisitions, and construction specifications for this retrofit. The horizontal take-up is seen in the above photograph taken during the construction period.

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