An unusual method of separating or fractionating fine-particle slurries has been proposed and partially explored by Landin (1980), Papanu (1983Papanu ( , 1986, Menon (1983), Lennartz (1984), and Lennartz et al (1987). A helically coiled tube spinning steadily on its major axis is connected to two agitated reservoir pumps which cycle a slurry bidirectionally through the helix as shown in Figure 1. With appropriate pumping steps, slurries can be concentrated or fractionated. The operation can be made continuous by adding feed at F and withdrawing products at I and 11.Research is motivated by the prospect of achieving sharp separations with fine particles smaller than about 10 pm. The technique is inherently multistage; the number of theoretical stages is approximately equal to the helix tube volume divided by the fluid volume pumped per cycle. The number of theoretical stages increases with reduced pumping volume.In this work, the method is further explored for fractionation.Early investigators found that separation was hindered by material accumulation in the helix, caused by ineffective particle resuspension, an essential step of each cycle. A new equipment design provides more effective particle resuspension by reorienting sedimented particles in the centrifugal field. A mathematical model is developed to describe and simulate the process. Data from a batch fractionation experiment using a sand/kaoh-clay slurry is reported. Fractionation-Six-Step SequenceA slurry containing two types of particles, A and B, with different settling rates, is fractionated by convecting particle-free fluid, slurry containing B, and slurry containing both A and B, a t By the end of this step, secondary flows are generated, due to an imbalance of centrifugal forces in the helix cross-section. These secondary flows resuspend sedimented solids in step 5. If these secondary flows are inadequate for particle resuspension (the particles collect at a stagnation point), the helix cross-section may be reoriented in the centrifugal field to move sedimented solids back into the fluid stream during step 5. Figure 2 shows these secondary flows, axial flows, and centrifugal forces, for cases where the fluid flow opposes or complements the spinning direction. In step 6, resuspended A and B particles are convected leftward with fluid, toward the A-rich reservoir. The sum of volumes pumped left in steps 4 and 6 equals the volume pumped right in step 2; no net fluid movement occurs. At the end of the sequence, there has been a net movement of B particles toward the right reservoir and A particles toward the left reservoir. Repeating the sequence indefinitely, increases the degree of fractionation until steady state is achieved with balance axial dispersion and axial separation effects. ModelThe six-step fractionation cycle is modeled by material balances for the suspended and the sedimented particles. Since the helix fluid velocity profiles are not known precisely, the model detail is limited to a one (space) dimensional axial dispersionconvection ap...

A conceptual design was prepared for the excavatiodredisposal remedial action in order to support the development of detailed plans and specifications. The conceptual design included all elements ofthe design upon which the cost estimates used in the cost-effectiveness evaluation were based. DETAILED DESIGNPreparation of detailed plans and specifications for the McColl remedial action included development of two bid packages. The first was for site preparation activities including the installation of utilities, grading, fencing, construction of roads, and vehicle weighing and washdown facilities. The second bid package included air emission control and treatment systems, water and electrical utilities, excavation of contaminated soils and hazardous wastes, transportation and redisposal of excavated materials, and site work and demolition required for final clo-Ann E. St. Clair is a Senior Geologist iiiid Ilepiirtiiient Head at Riidiiiii Corporatioil. She eiiriietl her B.A. in Geology from Trinity University iintl X.I.A. iii Geological Sciences froiii The University of Texas at Austin. She has over ten yeiirs experience in evaluation of eiivironiiieiital impwts of energy iuitl iiitlustrial develo iiieiit and waste disposal. 111 recent years, she has &ected a variety oflarge proviiiiis in the hazardous waste iireii aiirietl at he finit ion of prolileiiis auic~ selecting remecIiat ineiisures. She is ;in AIPG Certified Professional Geological Scientist and ii nieml)er of the Ground Water Techiiolo&y Division of the National Water Well Association.sure. Proposers were also required to submit safety and transportation plans. The selection process for remedial action contractor is expected to be completed in mid-1984. CONCLUSIONSThe approach to feasibility study and design of remedial action at uncontrolled hazardous waste sites outlined in National Contingency Plan is very valuable in selecting iind designing the cost-effective alternative. The thorough and systematic application of this approach for remedial action at the McColl Superfund site in California resulted in recommending the cost-effective alternative to the California Department of Health Services. The case study also demonstrated the need for involvement of a variety of technical disciplines in defining the problem, evaluating numerous complex technologies, developing and evaluating alternatives, testing (field and laboratory) for detailed evaluation, and designing the cost-effective remedial action. Kishore T. Ajmera, P.E. is a Senior Civil Engineer at Hatliiin Corporiction, i u i d earned his B.S.C.E. ;it Pooiia University, India, a i d his M.S.C.E. ;it the University of Texas at Arlington. He has Over seventeen years of experience in environmental consulting ant1 construction iiiaiiiigement. He hits worked 110th in private and goveriiiiient ;rnd recent emphasis of his work at Rotlimi has Iieeii in solid antl hazardous wiste iiiaiiiigemetit. Prior to joiiiiiig Radian in 1981, he was ti Senior Project Engineer for the Texas Depsrtiiieiit of Health aiitl ...

Technology Management Inc. (TMI), teamed with the Ohio Office of Energy Efficiency andRenewable Energy, has engineered, constructed, and demonstrated a stationary, low power, multi-module solid oxide fuel cell (SOFC) prototype system operating on propane and natural gas. Under Phase I, TMI successfully operated two systems in parallel, in conjunction with a single DC-AC inverter and battery bus, and produced net AC electricity. Phase II testing expanded to include alternative and renewable fuels typically available in rural regions of Ohio. The commercial system is expected to have ultra-low pollution, high efficiency, and low noise.The TMI SOFC uses a solid ceramic electrolyte operalting at high temperature (800-1000 °C) which electrochemically converts gaseous fuels (hydrogen or mixed gases) and oxygen into electricity. The TMI system design oxidizes fuel primarily via electrochemical reactions and uses no burners (which pollute and consume fuel) --resulting in extremely clean exhaust. The use of proprietary sulfur tolerant materials developed by TMI allows system operation without additional fuel pre-processing or sulfur removal. Further, the combination of high operating temperatures and solid state operation increases the potential for higher reliability and efficiencies compared to other types of fuel cells.Applications for the TMI SOFC system cover a wide range of transportation, building, industrial, and military market sectors. A generic technology, fuel cells have the potential to be embodied into multiple products specific to Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) program areas including: Fuel Cells and Microturbines, School Buildings, Transportation, and Bioenergy. This program focused on low power stationary applications using a multi-module system operating on a range of common fuels.

Technology Management, Inc. (TMI) of Cleveland, Ohio, has completed the project entitled "Small Scale SOFC Demonstration using Bio-based and Fossil Fuels." Under this program, two 1-kW systems were engineered as technology demonstrators of an advanced technology that can operate on either traditional hydrocarbon fuels or renewable biofuels. The systems were demonstrated at Patterson's Fruit Farm of Chesterland, OH and were open to the public during the first quarter of 2012. As a result of the demonstration, TMI received quantitative feedback on operation of the systems as well as qualitative assessments from customers. Based on the test results, TMI believes that > 30% net electrical efficiency at 1 kW on both traditional and renewable fuels with a reasonable entry price is obtainable. The demonstration and analysis provide the confidence that a 1 kW entry-level system offers a viable value proposition, but additional modifications are warranted to reduce sound and increase reliability before full commercial acceptance.