INTERIM FINAL TECHNICAL REPORT
September 1, 1996, through August 31, 1997
Project Title: FURTHER DEVELOPMENT OF A COPPER OXIDE DESULFURIZATION AND NOx REMOVAL SYSTEM
ICCI Project Number: 96-1/2.1A-5
Principal Investigator: David G. Sloat, Sargent & Lundy
Other Investigators: Joseph N. Darguzas, Sargent & Lundy; Raj Gaikwad, Sargent & Lundy; Jeri C. Penrose, Sargent & Lundy
Project Manager: Herman F. Feldmann, ICCI
ABSTRACT
This work supports continued development of the copper oxide process for controlling emissions of sulfur dioxide and nitrogen oxides from coal combustion. This advanced process utilizes a moving bed of regenerable sorbent to capture sulfur oxides from hot flue gas and recover the collected sulfur as a saleable by-product such as fertilizer, elemental sulfur, or sulfuric acid instead of producing large quantities of solid waste requiring disposal. At the same time, the sorbent catalytically reduces nitrogen oxides. Previous pilot studies have confirmed the process is capable of high removal efficiencies for both pollutants while firing high-sulfur Illinois coal; and previous economic studies have shown the process is an attractive alternative to conventional flue gas desulfurization technologies.
The current project builds on the successful pilot testing performed to date by continuing to test additional process parameters and includes testing at the Illinois Coal Development Park at a scale an order of magnitude larger than previous pilot scale work. This work is part of a total development program, and other copper oxide development activities are ongoing through the U.S. Department of Energy LEBS program.
The current study includes investigation of three areas:
1. Evaluation of byproduct generation options
2. Assessment of the possibility of PCB formation with copper oxide
3. Characterization of SO3 removal efficiencies for copper oxide
In general, this work addresses technical issues peripheral to the main process which has been to focus of development efforts to date. These issues are necessary steps toward eventual commercial acceptance of the process, and concurrent work in these areas in parallel with ongoing process development will hasten commercialization of the technology.
EXECUTIVE SUMMARY
Any user that expects to fire Illinois Basin coal will either need to install an FGD system or, if a utility, acquire SO2 allowances for the plant to operate from year-to-year or possibly both. FGD technology and other flue gas cleanup technologies have advanced since the first systems were installed in the 1970's. The advances have improved reliability and reduced costs.
The copper oxide process promises to be an economical and attractive flue gas desulfurization process for Illinois coals with medium to high sulfur content. The process uses a regenerable sorbent in a moving bed to simultaneously capture sulfur dioxide and catalytically reduce nitrogen oxides in flue gas. Regeneration of the sorbent then releases the sulfur dioxide in a concentrated stream for recovery. The sulfur dioxide is recovered as a byproduct such as fertilizer, elemental sulfur, or sulfuric acid for sale rather than generating large quantities of waste products as with some other FGD options.
The U.S. Department of Energy (DOE) Pittsburgh Energy Technology Center (PETC) has performed pilot scale parametric testing of the process which showed sulfur dioxide removals greater than 93% when firing a 2.6% sulfur Illinois coal. Over 90% NOx removal has also been realized. A series of tests established performances for varying flue gas flow rates, sulfur concentrations, adsorber operating temperatures, and sorbent flow rates. Tests also defined sorbent regeneration parameters including regeneration temperatures, sorbent residence times, and regeneration gas flow rates. These results validated the process model and provided a basis for continued process development. Economic analysis indicated the process is competitive with other FGD technologies, particularly when NOx removal is required.
The next step in the continued development of the copper oxide process is being performed in an ongoing pilot program at SIUC test facilities. In this program, existing facilities have been modified to combust pulverized Illinois coal to produce flue gas for testing. A medium-scale copper oxide pilot plant has been constructed and will treat the flue gases from the test facility to remove SO2 and NOx. This pilot plant is an order of magnitude larger than the pilot plant at PETC and is one-tenth the size anticipated for commercial adsorber modules.
This work will advance the technical and economic basis for furthering commercialization of the process. A 50 MW Proof-of-Concept demonstration facility is planned as the next step of the copper oxide development program. The data obtained as a result of this proposed work will be a critical component of that development process.
This project consists of three smaller studies:
1. Evaluation of byproduct generation options including more detailed characterization of the concentrated SO2 stream from the process and engineering evaluation of conversion of the recovered SO2 to sulfuric acid, elemental sulfur, or ammonium sulfate byproducts for sale
2. Examination of the potential for PCB formation in the copper oxide adsorption bed
3. Characterization of SO3 removal efficiencies for copper oxide and determination of resulting acid dew points in the desulfurized flue gas.
In general, the work addresses technical issues peripheral to the main process which has been to focus of development efforts to date. These issues are necessary steps toward eventual commercial acceptance of the process, and concurrent work in these areas in parallel with ongoing process development will hasten commercialization of the technology.