Ceramic balls

Furthermore, 60—100 L (14—24 gal) oil, having sulfur content below 0.4 wt %, could be recovered per metric ton coal from pyrolysis at 427—517°C. The recovered oil was suitable as low sulfur fuel. Figure 15 is a flow sheet of the Rocky Flats pilot plant. Coal is fed from hoppers to a dilute-phase, fluid-bed preheater and transported to a pyrolysis dmm, where it is contacted by hot ceramic balls. Pyrolysis dmm effluent is passed over a trommel screen that permits char product to fall through. Product char is thereafter cooled and sent to storage. The ceramic balls are recycled and pyrolysis vapors are condensed and fractionated. 

Despite this past downward trend, which has persisted in the United States since 1979 with modernization of large suppHers in Japan and Europe, growth of 2 to 2.5% is now expected into the mid-1990s. This reflects increased demand for some military appHcations and commercial aircraft, plus growing needs for farm and constmction machinery (2). U.S. production of the relatively new ceramic ball bearings is expected to increase distinctively by about 50% yearly to reach 17 million in 1993 (3). 

Ceramic ball beatings are also sometimes effective ki operation with water which would result ki rapid failure with steel beatings. This capabiUty may result from a thin hydrodynamic film formed from very small hydrated Si N wear particles and the water (44). 

Hybrid beatings uskig Si N ceramic balls with M-50 or other tool steel rings enable operation up to 300°C while avoiding the difficult manufacturkig problems with ceramic rings (45). 

Figure 5-4d is a schematic of a ceramic ball flame-arresting element. 

In this particular example as in many others, a proper analysis of cost is a crucial factor. An example is the production of balls for ball bearings. Coated ball bearings (or monolithic silicon nitride) greatly outperform steel balls but their cost is considerably higher. Steel balls in passenger-automobile applications are satisfactory and normally last the life of the car and the far-longer life of the ceramic balls is not needed. 

Figure 2.12 Exploded (left) and assembled (right) view of a toroid cavity autoclave probe for in situ investigations under high gas pressures or in supercritical fluids. Autoclave base (A) and autoclave body (P-bronze, B) thermocouple (C) coaxial heater (D) PTFE ring (E) central conductor (Cu/Be ring, F) nonmagnetic pin from male coaxial connection (G) RF feedthrough (from Rathke [28], H) base-plate (MACOR, I) fixing screws (P-bronze, J) PEEK capillary (l<) ceramic ball (Si3N4, L) PTFE seal (M).

The process considered is the Colony hydrotreated shale oil plant using the TOSCO II pyrolysis retort (4). In this process raw shale, crushed to 1/2" or smaller, is contacted with hot ceramic balls in a rotating drum. Downstream of the retort the balls and spent shale are separated by screening. The balls are then transported by an elevator to a vessel in which they are reheated by direct contact with hot combustion gases. The heated balls are then recycled to the rotating retort. 

Figure 17.27. Catalyst packed adiabatic reactor, showing application of ceramic balls of graduated sizes for support at the bottom and hold-down at the top Rase, Chemical Reactor Design for Process Plants, Wiley, New York, 1977).

Reforming in the CRG process occurs adiabatically at 450-550 C at pressures up to about 600 psig (41 atmospheres). The reactor is a vertical cylindrical pressure vessel containing a bed of the special high-nickel catalyst which is supported on a grid or on inert ceramic halls. The gas flow is downwards through the bed and distributors are provided at inlet and outlet. A layer of ceramic balls on top of the bed prevents disturbance of the catalyst by the entering gas. 

The lanthanide salt hydrates and D were taken in the ratio Ln D 1 (2 3). Their mixture and 12 ceramic balls (d= 8-10 mm) were put into a corundum thick-wall reactor (volume 150mL) and exposed to the vibration (50 Hz, 1.5 kW) for 3-15 min. Then small amounts of solvents (ethanol, water, hexane, 3-10 mL) were added. The formed solid was recrystallized from acetone. Yields 85-92%. 

Crusher ball mill (156mim/> x 156mm), ceramic ball (25 mnu/> x 30). 

One process that was developed but not commercialized was the TOSCOAL process, in which crushed coal is fed to a horizontal rotating kiln. There it is heated by hot ceramic balls to between 425 and 540°C. The hydrocarbons, water vapor, and gases are drawn off, and the char is separated from the ceramic balls in a revolving drum with holes in it. The ceramic balls are reheated in a separate furnace by burning some of the product gas. 

Mixing is usually carried out in a ceramic ball mill with steel balls. The inevitable attrition of the mill balls leads to an addition of 0.5-1 wt% to the iron content for which allowance must be made. Care must be taken to maintain the quantity and size distribution of the mill balls and to remove those that have become so small that they cannot be separated from the slip or powder on sieving. 

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