Howard L. (Jeff) Empie
Professor
Contact Information
Building: Paper Tricentennial (IPST)
Office:
339
Phone: 404.894.9704
Fax: 404.894.4778
email
Mailing Address
Georgia Institute of Technology
School of Chemical &
Biomolecular Engineering
311 Ferst Drive, N.W.
Atlanta, GA 30332-0100
Links
Howard L. (Jeff) Empie
Education
B.S., 1964, Syracuse University
M.S. 1965, Massachusetts Institute of Technology
Ph.D. 1969, University of Minnesota
Research Interests
Dr. Empie's current research interests include black liquor spraying systems, odor reduction, green liquor clarification, and alternative kraft liquor recovery processes, focusing on fluidized bed technology. He has taught courses in Reaction Engineering, Chemical Recovery, and Mass and Energy Balances.
The purge of chloride from the kraft pulping/recovery cycle has been a persistent problem for many mills. High chloride levels have enhanced corrosion rates and sticky dust formation in recovery boilers, and led to increased fouling of heat transfer surfaces in evaporators and upper sections of the recovery boiler. Because chloride is soluble in all of the process liquors, economical separation and removal has never been achieved. Many mills have “solved” the buildup problem by simply dumping electrostatic precipitator catch due to its relatively high chloride concentration. This, of course, is not economical because, in addition to the disposal fees incurred, the sodium and sulfur content of these salts is also lost by this practice. A project is underway to develop a new alternative to purging chloride through the use of electrodialysis with ion selective membranes that efficiently generates two separate useful product solutions. By using the principle of electrochemical salt splitting with the addition of ammonia to the anolyte compartment, ammonium salts are produced which are useful as commercial fertilizer; in the catholyte compartment sodium hydroxide (caustic) is produced which can be added to the white liquor. Technical feasibility of the method needs to be established along with the design parameters for a commercial scale operation.
A kraft pulp and paper mill generates nearly half of its energy needs from combustion of black liquor. In mills where the recovery boiler has excess steam generation capacity, supplemental fuel oil may also be burned to achieve the steaming limit. In such cases, fuel economics could be improved by switching to lower cost petroleum coke. Technically, pet coke is potentially attractive because it has a high carbon content (>85%) whose other major component element is sulfur, which is generic to all kraft mills and hence could be considered as an alternative source of sulfur makeup. One minor impurity of concern is vanadium, which is known to promote corrosion in power boilers. Establishing technical feasibility of this idea requires qualitative and quantitative assessment of the differences in combustion characteristics of a black liquor-pet coke mixture versus black liquor alone. The addition of petroleum coke may alter the spray drop size and the swelling characteristics of the droplets formed prior to combustion. Quantification of any significant differences introduced by pet coke would be needed to help the recovery boiler operator establish a new target for spray drop size. The IPST @ Georgia Tech Single Particle Reactor has been used to determine differences in black liquor swelling and combustion behavior for individual black liquor drops without and with pet coke added.