Differential speed

The rolling operations that foUow take place first on hot (95°C) differential-speed roUs which dry and coUoid the paste and convert it iato sheet form, and then on even-speed roUs which produce smoothly surfaced propellant sheets ia which all iagredients have been uniformly iacorporated. The roU gap ia the differeatial roUs is adjustable to produce sheets of various thicknesses, and rolling is continued until the moisture is reduced to a predetermined level, usually less than 0.5%. The sheet is then cut off the roU. Differential rolling is potentially hazardous, and fires are not uncommon, although detonations are not apt to occur. Operations are conducted by remote control. 

Power for each Hquid and the soHd phase must be added to get Pp. P, the soHds process power, = T -AN for scroU decanters, where = conveyor torque and AN = differential speed between bowl and conveyor. Pp is the friction power, ie, loss in bearings, seals, gears, belts, and fluid couplings. P, the windage power, = K and fi = viscosity of surrounding gas p = density of gas D = rotor outside diameter N = rpm and K = shape... 

Soft solids, most of which are biological waste such as sewage, are difficult to convey up the beach. Annular baffles or dams have been commonly used to provide a pool-level difference wherein the pool is deeper upstream of the baffle toward the clarifier and lower downstream of the baffle toward the beach. The pool-level difference across the baffle, together with the differential speed, provide the driving force to convey the compressible sludge up the beach. This has been used effectively in thickening of waste-activated sludge and in some cases of fine clay with dilatant characteristics. 

Paint-grinding roller mills (Fig. 20-52) consist of two to five smooth rollers (sometimes caUed rolls) operating at differential speeds. A paste is fed between the first two, or low-speed, rollers and is discharged from the final, or high-speed, roller by a scraping blade. The paste passes from the surface of one roller to that of the next because of the differential speed, which also apphes shear stress to the film of... 

Any form of natural rubber which is marketed with the rough surface produced by passing the rubber through a series of mills with grooved rolls travelling at differential speeds. The main types are pale crepe, sole crepe, brown crepe and flat bark crepe. 

Machines may be tailored to meet specific process requirement by altering the diameter of the liquid discharge, the differential speed of the helical scroll, the position at which the... 

As shown in Fig. 19, polymer adheres to one of the two counter-rotating rolls passing through an adjustable nip gap which creates intense shear. The rolls are temperature controlled and may run at differential speeds to influence further shear intensity. A degree of lateral cross-mixing must also be imposed to ensure overall compositional uniformity of the batch. A rolling bank of polymer located above the rolls provides some additional mixing capability. 

Polymers, plasticizers, stabilizers, and ionic impurities were blended by masticating 5 to 15 min. on a 6 inches x 12 inches two-roll differential-speed mill, adjusting the temperature between 40° and 175°C. according to the thermal plasticity requirements of the different compositions. 

Table III. Milling of Emulsion Polymers on a 6" X 13" Two-Roll Differential Speed Mill...

The crude gel suspension of epichlorohydrin cross-linked poly(allylamine hydrochloride) was fed to an Alfa Laval CHNX 318 at 9.5 to 12.3 L/min with bowl speeds of 2500 rpm to 3250 rpm and differential speeds between 1.3 and 10 rpm. The discharged gel had a moisture content of 75% to 82%. 

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