Unloading Big Trains Into Little Hoppers:New Unit Train Unloading Facilities at Dynegy's Wood River Station

Introduction
Dynegy Midwest Generation operates the Wood River Power Station in Wood River, Illinois. The plant has recently converted to the utilization of Powder River Basin coal. Coal can be delivered via barge to an unloading dock on the Mississippi River, or can be delivered via rail. The plant consumes approximately two million tons of coal per year.

The existing rail-unloading hopper was part of the original plant construction. The hopper holds approximately 45 tons, and is capable of transporting coal away from the hopper at a rate of 1,000 tons per hour. Ladder tracks and a switch engine have been used to position coal cars over the hopper for unloading.

Dynegy decided to construct improved railcar unloading facilities, in order to lower their coal transportation costs by being able to accept delivery of unit trains and to be able to unload those unit trains in an acceptable period of time. Dynegy retained the services of CDG Engineers of St. Louis, Missouri to perform preliminary studies for the project, and CDG ultimately provided the design engineering services for the project.

New Rail Unloading Facilities
A route was chosen for a new rail loop, which circles the plant property and allows unit trains of more than 135 hopper (and up to three locomotives) to be handled. A vehicular road that provides emergency access into the plant site was constructed, by using a large diameter corrugated steel pipe that allows the trains to pass through the access road embankment.

It was decided that the existing rail unloading hopper and reclaim conveyor system would be re-utilized, and a car positioner would be added to enable plant staff to exactly locate railcars over the existing hopper, since the small size of the hopper made precise railcar placement imperative. The use of the car positioner also enables the plant to effect the unloading process without the train crew being present, and with minimal plant staff involvement.

Heyl & Patterson, the same company that had recently supplied a similar system as a part of a rotary dump unloading system for Dynegy's Baldwin Plant, supplied the car positioner system. The positioner system includes a 350 h.p. cable winch-type drive, which utilizes D.C. power to move the positioner arm. The positioner arm is placed over railcar couplings, and the cable winch powers the arm to move the train to position the next car to be unloaded. Ultra-sonic sensors are used to control the positioner. "Hot-shoe" devices communicate with devices mounted on the railcars to allow the operator to open and close the doors of the bottom dump cars without leaving the operator's building. There is also a "retarder" that holds the train in place while the positioner arm is moving to the next coupling.

Summary
Dynegy was able to begin unloading unit trains at the Wood River Power Station in early 2004, and to significantly lower their fuel transportation costs. The use of the car positioner enabled the unloading hopper to remain in service, even though the railcars being unloaded hold more than twice the volume of the unloading hopper. The exact positioning enables the plant to position the railcars and leave them in place while the hopper fills and the cars empty. It is estimated that the project cost would have doubled if the unloading hopper were to have been replaced.

This article was prepared in a joint effort by Rick Lodewyck of CDG Engineers and Joe Mansker of Dynegy The thoughts and opinions expressed in this article and should not be construed as representing the thoughts or opinions of the American Coal Council or its members companies, Dynegy, or CDG Engineers.

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