The Raring Corporation: Fog Based Dust Control Systems for Rail Dumps Handling PRB Coal

This article was prepared by David Raring, President of The Raring Corporation on Raring's ADS - Dust Control System. This article represents the opinions and views of the author(s) only and should not be construed as representing the views of the American Coal Council, any of its members, or any other party.

The Raring Corporation: Fog Based Dust Control Systems for Rail Dumps Handling PRB Coal

For power plants burning PRB or similar coals, one of the most challenging tasks is to control fugitive and nuisance dust at the point of receipt. Successful dust suppression and extraction installations can be found in the industry but the vast majority of plants who have converted to PRB coal have a need to improve their dust control systems and would like to reduce operating and maintenance cost.

The Raring Corporation

Over the past ten years, fog-based and passive dust control systems have replaced virtually all dust extraction systems in the PRB mines from truck dump to load-out. Over the past several years, fog and passive technology has also found its way into coal-fueled utilities, being broadly applied at transfer points, reclaim feeders, crushers, and bunker rooms and displacing traditional dust extraction. The industry and the engineers that serve it generally accept those applications.

Over the past three years, The Raring Corporation has focused its attention on the "point of receipt" problem. Beginning with a system for a turn-over car dumper in the Midwest, we have addressed the issues of containment, operation in sub-freezing weather, automated control, installation in a normal outage and plant personnel "buy-in." Since then, we have added three rotary rail dump installations, a bottom dump and two barge unloading applications that are in successful operation at plants in Arizona, Michigan, Wisconsin, Nebraska and Illinois.

The most recent rotary dump application incorporates our latest thinking in containment design and control. Located in an upper Midwest power plant burning PRB coal, it is an older Link Belt dumper with cable drive and four cable-driven clamps. It is situated inside an unheated building fitted with a dust extraction system without modern airflow containment features.

Visibility was obstructed by dust, causing the operators to use the presence of coal on the barrel as an indicator of a full hopper. This led to frequent unloading delays and maintenance problems.

Wash down after each train to remove many inches of dust from the hopper level machine floor and the track-level access platforms required a full shift. A vacuum truck had to be used where the dust was deep to prevent explosive dust clouds.

After an initial evaluation, a graphic 3-D model of the dumper was constructed and containment requirements defined. The model was then presented to the client who included their operating and maintenance personnel in the process. Working together, a containment design that was both functional and user friendly was agreed upon.

To secure the investment dollars, a performance guarantee was required that would insure a minimum ROI. The ROI was to be based on the reduced cost of operation, clean up and maintenance. TRC guaranteed that there would be not more than one quarter inch of dust (on average) on the access and machine floors after five trains and that the fog system would not increase the time required to unload a train. Further, Raring guaranteed to meet all applicable local, state and federal air quality regulations.

The system went into full service in early May of 2005. The utility is very pleased with the results. The guarantees have been met and the state EPA has accepted the conversion. In most areas around the dumper, there is only trace dust after five trains and in the worst areas, not more than the one quarter inch promised as an average. Operating horsepower has dropped from the several hundred horsepower of the dust extraction system to approximately 30 equivalent horsepower of compressed air taken from the plant high-pressure soot blower air source. Although the utility chooses to continue to wash-down after each train, it is now a ten-minute job and can be dispensed with without risk during cold weather. Routine maintenance is now limited to occasional nozzle cleaning and replacement, small valve repair and changing filters. The major maintenance associated with a baghouse is gone.

All three of the rotary rail dumps that have been fitted with Raring fog systems had existing dust extraction/baghouse systems. In two of those cases, the baghouses were not performing well and the fog was installed to improve dust control. In the third case, the baghouse was performing well and the fog was installed simply to reduce cost. In all three cases, the performance and ROI would catch the attention of any cost-conscience plant manager.

There was one additional benefit to each of the utilities. There is now one less stack (point source) to monitor and report to the EPA.

In conclusion, fog-based dust control is now a proven and cost-effective option for rail and barge unloading facilities using PRB coal.

About the author. Mr. Raring is the President and founder of The Raring Corporation and has worked with fog based dust control technology since its development in the 1970's.

About The Raring Corporation. TRC is a 21 year old privately held corporation based in Vancouver, Washington. Their primary product is their patented ADS - fog based dust control system. Their primary niche markets include the major minerals mining and processing industry worldwide and PRB coal handling in the US.

Those who would like to learn more about The Raring Corporation's ADS - fog based dust control system can go to The Raring Corporation's web site at http://www.raringcorp.com/