Press double roll

The most widely used roller presses are double roll presses which achieve compaction by squeezing material between two counter-currently rotating rollers (Figure 222), much in the same manner as the operation of rolling mills. Pockets or indentations, which have been cut into the working surfaces of the... 

Figure 222. The basic principle of double roll pressing...

Figure 225. Drawings of an early double roll briquetting press designed by Schiichtermann...

Figure 221. Double roll pressing geometry, angles, and roll force. Compaction of particulate matter in the nip of a smooth roll press...

As a result of efforts to develop an economical method for the task, the double-roll press was invented during the second half of the nineteenth century in Europe. 

B. Atkinson, Compaction of powders and pastes in double roll presses, NCB/CRE/Solid Products Department Report No. 108, Feb. 1964. 

H. R. A. Lane, B. Atkinson, and S. Harvey A theory for the compaction of powders and pastes in double roll presses, NCB/R D Department (CPC), Coal Research Establishment, Solid Products Department, Report No. SP 116, Dec. 1965. 

In pressure agglomeration, the distance between the surfaces of compacting tool sets specifically in extrusion, the distance between the pressure generating device and the die plate, in roller presses, the closest distance between the rollers. Double-roll pellet mill in which the rollers are in the shape of coarse, intermeshing gears with bores at the root sections between the gear teeth. (Also gear pelletizer.) Distribution plate in which the perforations are manufactured such that they produce a directional flow of gas. See melt solidification. 

Fig. 8.120 Drawing of an early double roll briquetting press designed by Schuchtermann and Kremer (a company no longer existing), w, W = Roller shafts f, f, = Rollers with briquette pockets z = Internal coupling gears v = Feeder, pan with rotating distributor arms.

Double-roll presses and rotary table presses are available for briquetting bituminous coal. Different processes for controlling the briquetting process were derived by development of methods for measuring pressing pressure with double-roll presses. Normally double-roll presses have a roll diameter between 24 and 60 in. (600-1500 mm) and the compression ratio does not usually exceed 2.5 1. In general, the compression time for the briquette form is less than 0.05. 

In the Ancit process (Figure 17.5), two components, an inert noncaking component (such as low-volatile coal, anthracite, or coke fines) and a binder component consisting of caking coals, are employed. The main feed coal is comminuted wet by being heated to approximately 600 C (1110°F). The off-gas from this reactor heats the binder coal in another, smaller flow reactor. The two coals, comminuted at different temperatures, are mixed in a vertical, cylindrical mixer (at 460 C-520°C [860°F-970°F]). At this temperature, the binder coal is softened and the mixture is then briquetted on double-roll presses. 

Fig. 14. Cross-sectional views of post-CMP cleaning using double-sided roller brushes. The two brushes roll in opposite directions to keep the wafer pressed against two rollers. The rollers are used to rotate the wafer and are withdrawn to allow the wafer to pass once the wafer is clean (a) a single-brush configuration and (b) a multiple-brush configuration.

Double base compositions can be manufactured without the application of organic solvents by heated rolling and pressing of -> Paste. 

Rotary tablet presses could be designed to be single, double, or triple sided. A single-sided press comprises one hopper, one set of compression rolls, and one takeoff chute unit whereas double- and triple-sided presses comprise two and three each... 

Figure 274(c) shows a drive train that is applied for contemporary medium and large scale roller presses. It employs a double output-shaft gear reducer (2/4) powered by a motor (5) by way of a torque-limiting clutch. The completely enclosed, dust-tight gearbox provides the necessary reduction in speed and the distribution of power to the two roll drive shafts (3). Precision gear-tooth... 

Fig. 8.49 is another schematic representation, published by one of the manufacturers (CPM), showing the typical design of a pellet mill with cylindrical die and two internal press rollers. The execution suggested by Fig. 6.4b.5 (Chapter 6), 8.40, and 8.41 with one press roller is only used in laboratory and small production machines. For structural and process reasons, the perforated concave die can not be very wide (Fig. 8.50). Therefore, to increase the capacity of a given press and more uniformly distribute the forces acting on the ring, up to three rollers (see below. Fig. 8.52) are installed. With two rollers (Fig. 8.49) the capacity of a machine doubles as compared with a single roll pellet mill and triples with three rollers from a ring loading point of view, the latter also results in the best distribution of the pressing forces.

More surprising was that lost time for press section breaks more than doubled. The web is fully supported until the final press roll on this machine. There was a... 

A sUica sol-manganese nitrate solution is prepared in a Waring blender, as described in Example 1. To this is added 43 g of soluble starch. The mixture is stirred for 15 min after the addition of the soluble starch. The solution is drum-dried by feeding it slowly to the nip of a double drum-drier having 6-in.-diameter rolls. The roll clearance is 2 mils and the roll speed 2 r/min. The surface temperature of the rolls is 263°F. The dried powder is screened through a 50-mesh sieve and pressed into bars and calcined to form silica-supported catalysts as described in Example 1. 

Figure 3 Straight-side press with two double-acting cylinders and a rolling bolster.

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