Final Report: New Granular Sorbent Sulfurization Process for Vapor- and Liquid-Phase Mercury Control

EPA Contract Number: 68D03034
Title: New Granular Sorbent Sulfurization Process for Vapor- and Liquid-Phase Mercury Control
Investigators: Nowicki, Henry G.
Small Business: Professional Analytical and Consulting Services Inc. (PACS)
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: April 1, 2003 through September 1, 2003
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2003) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , SBIR - Waste , Small Business Innovation Research (SBIR)

Description:

Environmental regulations have drastically lowered the amount of mercury emissions released into the environment. Hospitals, domestic and industrial uses, and emissions from municipal and hospital incinerators have met the new regulations. With these environmental regulations promoting reductions in mercury emissions, the "spotlight" now is on mercury emissions from coal-burning electric power plants. Regulations also are expected to promote solutions to this major part of the problem.

One of the most expensive aspects of mercury control technologies is powdered sorbent injection. Injection of sorbents into the flue duct before the baghouse and other particulate control technologies appear to be the direction future solutions will take. During this Phase I research project, results obtained by PACS, Inc., indicated at least two new sorbents that can significantly lower costs and provide better mercury removal performance. These two new sorbents provide 50 percent and 20 percent cost savings compared to the sorbent currently in use. These least cost sorbents, which have superior performance over their competitors, potentially are an important part of the solution to this problem.

Summary/Accomplishments (Outputs/Outcomes):

Successful completion of this Phase I research project resulted in several innovations, which may help remove the trace mercury (ionic and elemental forms) problem in flue gas from coal-burning electric power plants. These innovations include:

  • The least expensive and best solution for removing mercury and other toxic trace metals from coal-burning electric power plant emissions may be the direct addition of compounds that can remove metals present in flue gas before the baghouse or other particulate-removal technologies. Direct chemical addition of specific compounds in this Phase I research project have not been completed, but is planned for Phase II using prototypes and a coal-burning pilot plant to evaluate mercury control. In Phase I, it was observed that mercury readily reacted with specific compounds.
  • A new process to manufacture chemical impregnated granular and pelleted activated carbons for the mercury application was demonstrated in Phase I. These new impregnated activated carbons outperformed two presently used commercial activated carbons from two different vendors with the same chemical impregnant.
  • The new sorbent chemical impregnation process yielded relatively homogenous chemically impregnated granular and pellet-activated carbon products (i.e., impregnate evenly spread throughout the activated carbon materials' porous nanostructure). Thus, grinding these new materials to a powder will have the active mercury-capturing "chemical" on all particles. Currently available heterogeneously chemically impregnated activated carbon commercial products yield many particles with no chemicals and with thick unreactive layers.
  • Current commercial impregnated activated carbon products have most of their active chemistry on the exterior of their granules and pellets.
  • Determining exterior particle chemical amounts required development of a new test method based on the rock tumbler used by geologists. This project demonstrated that it is possible to remove the exterior layer of activated carbon materials and perform chemical analyses and compare results with the whole starting granules or pellets to determine the chemical impregnant distribution in granular and pellet-activated carbons.
  • This new impregnation process developed in Phase I is capable of manufacturing many different chemically impregnated activated carbons and other sorbents. This process is capable of being patented. Competitor sorbent manufacturers will have interest in licensing this technology.
  • A new instrumental method, the gravimetric relative percent difference (GRPD), accurately determined the predicted adsorption performance of activated carbons and evaluated fly ash and/or activated carbon and fly ash mixtures to determine if they are useable for concrete manufacturing. Adding activated carbon to fly ash can foul it for use in cement manufacturing. This is a major problem, because 15 percent of the U.S. fly ash is used by cement manufacturers. The current sorbents require high amounts of carbon per pound of mercury removed, resulting in fouled fly ash. The use of new sorbents results in less fouling for cement than the present competitors. The GRPD instrument will be useful in proving this claim.
  • This Phase I research project demonstrated that a good negative-cost sorbent base for chemical addition for mercury control applications is available. This base material would provide a starting negative cost and the marketplace would provide ample amounts to satisfy much of the mercury applications.

    Conclusions:

    Two major project innovations, direct chemical insertion into duct work and chemically impregnated used sorbent base material, are the least expensive solutions for mercury control. The current competitor cost of powdered sorbent injection at power plants is 50 cents per pound. The two innovations developed during this Phase I research project offer sorbent injection at 25 and 15 cents per pound. However, these new sorbents offer advantages in addition to least cost. The new sorbents would require much less material to remove a pound of mercury. Less sorbent usage would allow more fly ash to be used by concrete manufacturers. Current sorbents often foul fly ash for concrete manufacturing.

    The Phase II research project will evaluate these two new sorbent inventions using prototypes and pilot-scale evaluations. This is reported to be a $3 billion market. At present, there is no satisfactory sorbent solution.

    Supplemental Keywords:

    granular sorbent sulfurization process, mercury control, mercury vapor, mercury emissions, fly ash, sorbent injection, coal, power plants, chemically impregnated used sorbent, concrete manufacturing, activated carbon, gravimetric relative percent difference, GRPD, coal-burning electric power plants, small business, SBIR., RFA, Scientific Discipline, Air, Waste, TREATMENT/CONTROL, POLLUTANTS/TOXICS, Sustainable Industry/Business, Chemical Engineering, Air Pollution Control, air toxics, cleaner production/pollution prevention, Environmental Chemistry, Sustainable Environment, Treatment Technologies, Chemicals, Chemistry, Technology for Sustainable Environment, Civil/Environmental Engineering, Incineration/Combustion, Engineering, Engineering, Chemistry, & Physics, Environmental Engineering, volatile heavy metals, mercury, combustion gas streams, combustion sources, combustion emissions, regenerable adsorbent, dry sorbent, mercury emissions, flue gas, sorbent technology, liquid phase mercury control, treatment, sorbents, mercury absorbtion, mercury sorbents, mercury recovery, regenerable sorbent, heavy metals, flue gases