Belt driers

Fig. 4. Multiphase fluid and fluid—solids reactors (a) bubble column, (b) spray column, (c) slurry reactor and auxiUaries, (d) fluidization unit, (e) gas—bquid—sobd fluidized reactor, (f) rotary kiln, and (g) traveling grate or belt drier.

Compartment driers are closets or even rooms in which the material is spread on trays or in shallow pans. The operation is often discontinuous in order to make it continuous, the pans may be placed on trucks traveling on rails, and these are pushed through a tunnel in which warm air circulates. Belt driers and chain driers have similar goals. 

Belt Driers A belt drier consists of a set of hinged shelves between two endless chains. As the belt so formed travels on large sprocket wheels, its path lies within... 

Band-feder, /. flat spring, -fdrderer, m. belt conveyor, -kante, /. edge of a band, band head, -mass, n. tape measure, -stabl, m. band steel, strip steel, bandstreifig, a. banded, streaked, striped. Band-trockuer, m. belt drier, -wunn, m. tapeworm. 

Uses As a mild alkali accelerator in fine-grain developers and those of low activity in certain hardening fixing baths and in some acid hardeners, especially those intended for prints that are to be dried through heated belt driers and in gold toning baths to render them alkaline and to increase the rate of deposition of gold. 

Heat may be transferred directly as in the burning of solid fuel mixed with the particulates in the sintering of ores or indirectly as in the combustion of fuel to produce hot gases in pellet hardening. External heat transfer may also take place across a metallic surface as in drum and belt driers and flakers. 

Belt driers Centrifuges Falling film evaporators Moving bed reactors... 

Cotton, cotton linters or wood cellulose is made fluffy by a disintegrator a dried in a continuously working belt drier. Dried cellulose is continuously mix with nitrating acid in a prenitrator. From there the mixture passes into a t fibrator where very close contact is obtained between the cellulose fibres and t acid and all enters into an after-nitrator where the nitration is completed. 

The granules have to be dried immediately to achieve a higher strength. Belt driers are very suitable for this since, mechanically, they do not put much strain on the fresh soft granules. The dried granules have an apparent density of approximately 1.8 g/cm ... 

The filter cake can be oven dried, after which it requires crushing into small lumps prior to calcination. To reduce manual handling, the cake is often extruded into noodles onto a belt drier, where a flow of hot air through the pigment bed dries the product into small pellets. 

Most spray-dried instant coffees have been marketed in a granular form, rather than the small spherical spray-dried form, since the mid-1960s. The granular appearance is achieved by steam fusing the spray-dried material in towers similar to the spray drier. Belt agglomerators are also common. 

With respect to the fertilizing value of the manure it must be remarked that the drier the belt-dried manure, the shorter the heating process and the consequently slighter the loss of organic matter. 

The plug flow contacting of phases may be accomplished in many ways by countercurrent flow as in blast furnaces and cement kilns [Fig. 26. ( )], by cross-flow as in moving belt feeders for furnaces [Fig. 26.1(6)], or by cocurrent flow as in polymer driers [Fig. 26.1(c)]. 

The damp powder is fed directly to the belt from a hopper containing an agitator, and drying is accomplished at a rate of 140 lb (53 kg) per drier per hour, at a temperature of 72°C. The air supplied is heated to about 50°C by steam coils, and the temperature in the tunnel rises due to the heat from the lamps. 

Power consumption of the driers averages 0.196 kWh per pound of dry powder and drying time is approximately 60 min. The operation is safe. The only fire which occurred between 1942 and 1946 was one that was started deliberately to see what the result would be. It was brought under control so quickly that production was resumed in less than two hours, with no damage to the lamps, belt or housing (Olive 28]). 

Among other systems of driers, continuous apparatus transporting cellulose on a conveyor belt in a stream of warm air are widely used (Fig. 133). 

It may be dried before or after moulding in fluidized-bed continuous-belt or rotary-tube driers. 

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