State Water Resources Research Institute Program

Project ID: 2006TN27B
Title: Ash Pond Modeling and Computer Simulation to Predict and Efficiently Control Ammonia/Nitrates and Heavy Metals Discharge
Project Type: Research
Start Date: 3/01/2006
End Date: 2/28/2008
Congressional District: Second
Focus Categories: Water Quality, Water Use, Models
Keywords: Mathematical Models, Optimization, Pollution Control, Toxic Substances Water Quality Modeling Water Reuse
Principal Investigators: Bienkowski, Paul R.; Counce, Robert M.
Federal Funds: $ 25,000
Non-Federal Matching Funds: $ 93,080
Abstract: TVA and UTK have an on-going research effort to reduce fresh water consumption at TVA Fossil Plants while maintaining compliance with all current and anticipated future emission regulations through development of a computer simulation of the Kingston Plant. This proposal expands on this research with a 2 year, more generalized effort, encompassing three major tasks; (1) developing a generalized computer simulation for plant wide water balance, including temperature and relevant pollutants (currently in progress) (2) a theoretical and experimental effort to develop models for the transport and kinetics of Hg and oxides of mercury, Se, As and ammonia in the ash ponds and the interaction of these substances with ammonia along with their distribution between the aqueous and ash phases, and (3) applying the simulation in the second year of the project to identify process modifications at Kingston to reduce fresh water consumption in an environmentally friendly manner. There are two main water streams; 40 MGD of very dirty water sent to the ash pond and 1,296 MGD of clean water used in the condensers. The ash pond is a major source of discharges and potentially a major resource. TVA's efforts to reduce air pollution thorough the addition of SCR units (for NOx) and scrubbers (particulates and SOx) have essentially converted air pollution problems into ash pond water pollution concerns with ammonia/nitrate and mercury discharges and possibly As and Se (desorption from the ash). Task 1 has been on-going for 15 months with the development in ChemCad of the entire water balance at Kingston including predictions of the quantities of pollutants produced based on coal type, boiler operation, and air pollution controls. Water recycle/reuse is the major source for reducing fresh water intake, it is essential to incorporate into the simulation thermal effects and the build up and interacts of pollutants to understand their effects on plant operation and maintain compliance with current and anticipated future emission standards. We are incorporating into the simulation models for phosphates, SOx, NOx, Hg, Se, As, ammonia and chlorine and the interactions of ammonia, chlorine and SOx with these metals. This information will be derived from three sources, i) the literature, ii) experimental data from TVA?s data base developed from its 11 fossil plants, specific plant wide tests at Kingston and future plant wide tests at other TVA plants, and iii) a theoretical and experimental program (Task 2) based at ORNL specifically directed at the fate of As, Hg, Se, mercury oxides and ammonia in the ash ponds and the interactions of these substances with ammonia. The deliverables will be models for the fate and transport of these substances in the ash ponds for incorporation into the water balance simulation. Task 2 is essential because there is insufficient information in the literature to model the interactions of these substances in the ash ponds.

Second Year Objectives: Conduct a second plant wide test at Kingston to compare with the 2004 test conducted before all of the SCR units were in place and use this test as a further verification of the Kingston plant ChemCad model. Conduct a literature search and experimental program to develop simulations for the interactions of As, Se, ammonia and ash in the ash ponds and incorporate these simulations in the Kingston plant model. Incorporate the COMSOL simulation into the model to allow for a better representation of the ash pond by incorporating its fluid dynamics. Use of the ash pond as a remediation device is a very real possibility. In the Spring 2007 semester one ChE 490/488 design group (3 to 5 seniors) will use the ChemCad model to investigate remediation options for phosphates, mercury, SOx and ammonia at the Kingston plant ash pond.

Progress/Completion Report, PDF

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