As the coal power industry trends toward more stringent controls on wastewater solid and liquid waste streams, increasingly sophisticated unit operations and controls are required to properly manage these facilities. Here, TRAX shares one example of a TRAX high-fidelity simulator that supported the commissioning and ongoing operation of two types of waste treatment operations at a fossil generation plant.
In the example simulator, the first type of waste treatment was designed to collect and dispose of coal combustion residuals (CCRs), commonly known as coal ash. The modeled coal ash collection and dewatering system relied on a pair of Remote Submerged Chain Conveyers (RSCCs). These RSCCs were designed to convey and partially dewater settled coal ash and slag. To support this operation, TRAX modeled a complex network of sumps, surge tanks, and pumps, as well as critical utilities that supported ash removal and washdown.
The second waste treatment was designed to treat and control the discharge of low volume wastewater (LVW). The LVW treatment system employed unit operations that flocculated suspended solids, separated and concentrated these solids, then further dewatered them in a filter press to form a dense cake. The water stream that was separated from the floc was further purified in a gravity filter that strained out finer solids using a bed of anthracite and sand in a gravity filter. Some of the filtered water was subsequently recycled for process needs, while the remainder was discharged to the modeled environment. A network of sumps and surge tanks supported these operations.
Alongside the wastewater simulation, TRAX developed tutorial videos overviewing the processing steps, including proper startup, operation, and shutdown. The wastewater simulator provided the perfect platform for capturing the DCS operation of these systems, supplemented with visual enhancements that identify key manual operations, control permissives, process limits, and mouse movements, along with flow path overlays that explain more complicated operations. These videos allowed lengthy or repetitive operations to be condensed for greater efficiency. These videos were especially helpful as they were presented prior to the commissioning phase of the RSCC and LVW systems, providing its future operators with a vivid picture of the process in action.
Many wastewater treatment operations require chemical additives to control pH, enhance floc formation, and precipitate heavy metals and organic matter. TRAX is able to accurately model all required operations and chemistry for a variety of treatment processes by using existing modules in our software library. More information about our software, ProTRAX, is available on our website.
The TRAX simulator includes several noteworthy operator training features:
The requirement for proper path alignment and initiation of unit operations in order to attain hydraulic balance between the various subsystems
Pressure build up across the gravity bed as it filtered out fine solids – ultimately requiring a regeneration cycle to restore its “clean” performance
Recycling of recovered floc nucleation sand back to the flocculation tank
Proper management of chemical feeds in order to obtain the desired control of solids removal, pH, and turbidity
Pre-programmed malfunctions to simulate the failure of critical components such as clarifier agitators, solids pumps, and filter press hydraulics
Local operating screens to adjust water chemistry, control manual valves, and simulate remote communication from control systems
This tremendously enhances the value of a high-fidelity simulator, as a thorough understanding of the unit operations and critical utilities, controls interface, management of water chemistry and pollutant removal, and proper diagnosis and response to common malfunctions can be developed in a realistic, risk-free training environment.
