ProControl is an autonomous scheduler used to activate arrays of water cannons to control fugitive dust emissions from ground storage sites. It was developed in a cooperative effort between Virginia’s Department of Environmental Quality (DEQ), Simpson Weather Associates, and two Virginia coal terminals. ProControl is now considered a Best Available Control Technology (BACT) and is required under the terms of Virginia and Ohio coal terminals’ operating permits.
ProControl was developed in response to two conflicting problems. The public was complaining of dust problems near the terminals, requiring the terminals to employ water applied with manually-activated “rain birds” to spray the coal piles. The coal purchaser, however, wanting the highest thermal value of the coal, required that the coal’s moisture remain low and would impose a penalty if the moisture exceeded an agreed upon percentage.
Manual operation of water cannons has often proved ineffective. The sprays are usually started after emissions have begun, and often in weather conditions which render the spray ineffectual. Manual application also frequently allows too much water to be applied, increasing the moisture percentage beyond the bounds acceptable to the coal purchaser. ProControl was developed to resolve these problems simultaneously.
ProControl is based on a stress index called the K-factor which is used to determine when and how much water should be sprayed on coal piles to control fugitive dust emissions. The K-factor is an empirically derived quantity based on the physical and statistical relationships between environmental conditions and the potential for wind generated dust emissions from coal piles. ProControl adjusts the K-factor for rain and freeze effects to define the need for water to be sprayed by the computer-controlled suppression system. Based on the K-factor, ProControl will initiate one of the following actions:
- No action (no spraying is required)
- Spraying a “Demand Cycle” to suppress the predicted dust emissions
- Spraying an “Assurance Cycle” at pre-selected times, i.e., 3:00 a.m., 7:00 a.m., 11:00 a.m., and 1:00 p.m. if no other cycles have been run
- Spraying to recover from freeze events
The basic K-factor equations and instructions have been packaged by SWA into ProControl.
The basic ProControl system provides the following functions:
- Monitors the local weather and computes the drying potential for coal pile surfaces.
- Uses 12-hour weather forecasts to schedule special treatments such as manual application of chemical tarps, over spraying with water before a freeze, or tying down of equipment in anticipation of a major storm (with forecast service option).
- Automatically activates a network of water sprays for a prescribed period via interface with PLC network.
- Performs end-of-day calculations of estimated coal contributions to Total Suspended Particulate (TSP) at specified monitoring sites.
- Prepares reports required by regulatory agencies (upon request).
- Issues visual and audible alarms for pre-set conditions.
- Issues warnings of impending conditions that may compromise the effectiveness of the water sprays or the safety of facility personnel (with forecast service option).
- Archives data and operator comments for future reference and review by regulatory agencies.
- Ability to disable water cannon spraying based upon wind speed/direction conditions (i.e., not using water cannons which are ineffective because wind blows water away from the target).
ProControl incorporates the K-factor with additional functionality to provide coal terminal facility operators with critical information regarding the status of the weather instruments, water spray equipment, expected changes in weather (with forecast service option), and status of coal handling equipment. A version of ProControl known as ProControl Plus incorporates dust-monitoring instrumentation.