Carbon pilot plant process

Pilot plant development was carried out to provide data for process and engineering design as well as economic evaluations. The pilot plant also served to provide active carbon for research and evaluation studies. The major pieces of equipment used to carry out the pilot plant process development are depicted in their flow sequence in Figure 2. Since it was decided at the onset to concentrate on studying each process step rather than being distracted by materials flow problems, there was no actual continuous flow of material from one piece of equipment to another. Each operation was carried out and studied independently. Any material produced was stored in sealed barrels or drums and was moved to the next operation when needed. Moreover, the outputs of the various pieces of equipment were different. In terms of pounds of active carbon per hour, outputs ranged from 25 to 110. 

The TOSCOAL Process. The Oil Shale Corp. (TOSCO) piloted the low temperature carbonization of Wyoming subbituminous coals over a two-year period in its 23 t/d pilot plant at Rocky Falls, Colorado (149). The principal objective was the upgrading of the heating value in order to reduce transportation costs on a heating value basis. Hence, the soHd char product from the process represented 50 wt % of the starting coal but had 80% of its heating value. 

Both the Toth and Alcoa processes provide aluminum chloride for subsequent reduction to aluminum. Pilot-plant tests of these processes have shown difficulties exist in producing aluminum chloride of the purity needed. In the Toth process for the production of aluminum chloride, kaolin [1332-58-7] clay is used as the source of alumina (5). The clay is mixed with sulfur and carbon, and the mixture is ground together, pelletized, and calcined at 700°C. The calcined mixture is chlorinated at 800°C and gaseous aluminum chloride is evolved. The clay used contains considerable amounts of silica, titania, and iron oxides, which chlorinate and must be separated. Silicon tetrachloride and titanium tetrachloride are separated by distillation. Resublimation of aluminum chloride is requited to reduce contamination from iron chloride. 

Process development on fluidized-bed pyrolysis was also carried out by the ConsoHdation Coal Co., culminating in operation of a 32 t/d pilot plant (35). The CONSOL pyrolysis process incorporated a novel stirred carbonizer as the pyrolysis reactor, which made operation of the system feasible even using strongly agglomerating eastern U.S. biturninous coals. This allowed the process to bypass the normal pre-oxidation step that is often used with caking coals, and resulted in a nearly 50% increase in tar yield. Use of a sweep gas to rapidly remove volatiles from the pyrolysis reactor gave overall tar yields of nearly 25% for a coal that had Eischer assay tar yields of only 15%. 

Centaur A process for reducing sulfur dioxide emissions from sulfuric acid plants. An activated caibon with both absorptive and catalytic properties is used. The technology uses fixed beds of Centaur carbon to oxidize sulfur dioxide to sulfuric acid in the pores of the carbon. The sulfuric acid is recovered as dilute sulfuric acid, which is used a make-up water in the sulfuric acid production process. Developed by Calgon Carbon Corporation in the 1990s. Calgon Carbon and Monsanto Enviro-Chem operated a Centaur pilot plant at an existing sulfuric acid facility in 1996. 

HIsmelt A direct iron smelting process in which noncoking coal, fine iron ore, and fluxes and gases, are injected into a molten iron bath the carbon monoxide produced is used to prereduce the ore in a fluidized bed. Under development by CRA, Australia, since the early 1980s, joined by Midrex Corporation in 1988. Their joint venture company, Hismelt Corporation, commissioned a pilot plant at Kwinana, near Perth, Australia, in 1993. 

Seacoke A process for making tar and coke by carbonizing mixtures of coal and petroleum residuum. The tar would be used in an oil refinery and the coke would be used for generating electricity. The process was sponsored by the U.S. Office of Coal Research 1964-1969 the work was carried out by EMC Corporation, Atlantic Richfield Company, and Blaw-Knox Company. Results from the pilot plant were encouraging but the project was abandoned because the benefits were judged insufficient to justify the complexity. 

Foreseeable improvements that will increase operability and decrease operating costs of Fischer-Tropsch processes are the development for the fluidized-iron process of a catalyst that will not accelerate the reaction 2CO = C02 + C and will not be appreciably oxidized during the steady-state life of the catalyst and the development of a more active and mechanically stable catalyst for the oil-circulation process so as further to reduce Ci + C2 production. The hot-gas recycle process could be made operable by use of a catalyst that will be less active but more resistant to thermal shock which occurs during regeneration to remove carbon deposits, and during operation at lower end-gas recycle rates. The powdered catalyst-oil slurry process recently has been satisfactorily operated in a pilot plant by K6lbel and Ackerman (21). Although the space-time yield in this operation was low (10 to 20 kg. of C3+ per cubic meter of slurry per hour), the Ci + C2 production was less than one third of that... 

The source of water samples was a 4-m3/h pilot plant on the Seine River located upstream from Paris, France. The background organic concentration ranged from 2 to 3 mg/L. The process, shown in Figure 1, included an upflow solids contact clarifier (Pulsator, Degremont, Rueil Malmaison, France) followed by rapid sand filtration (RSF). The effluent of the RSF was then split into four lines, which received various levels of ozonation followed by granular activated carbon (GAC) adsorption. Postchlorination (0.2 mg/L residual after 1 h) was used for bacterial control. 

Hazards attendant on use of ethylene oxide in steriliser chambers arise from difficulties in its subsequent removal by evacuation procedures, owing to its ready absorption or adsorption by the treated material. Even after 2 evacuation cycles the oxide may still be present. Safety is ensured by using the oxide diluted with up to 90% of Freon or carbon dioxide. If high concentrations of oxide are used, an inert gas purge between cycles is essential [7]. The main factors in safe handling and use on laboratory or small pilot plant scales have been identified [8]. Safe operation of ethoxylation processes on industrial scale is discussed, with case histories [15],... 

A riser pilot plant has been successfully used to process heavy feedstocks with Conradson carbon contents as high as 10%w. 

Shell Canada s Oakville Research Centre has had a riser pilot plant in operation for about ten years. A series of modifications have been made to the unit over the years in order to improve its ability to process heavier feedstocks. In spite of a rather low feedrate of 0.52 g/s (approximately 0.3 B/D), poorer quality feedstocks have been processed than those described above. To date, feedstocks with Conradson carbon contents up to 9.9%w and viscosities up to 120 cSt at 100 C have been successfully run in the ORC pilot plant. Operating experience with the pilot plant is summarized in Table I, and a schematic is shown in Figure 2. 

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