Heated drum

They consist essentially of a revolving, internally heated, drum, on which a film of the solids is deposited and dried. The film is formed either by immersing part of the drum in a trough of the liquid or by spraying, or splashing, the feed on to the drum surface double drums are also used in which the feed is fed into the nip formed between the drums. 

Continuous vulcanisation of rubber based products such as thin conveyor belting, flooring and similar can be achieved using a large rotating heated drum. Pressure is exerted to the product by means of a continuous stainless steel belt which presses the sheet to the surface of the drum. The belt is also heated from its reverse side to give optimum heat transfer to the vulcanising rubber. 

Grains. Grains are usually prereduced powders. The quantities of sodium sulfide, hydrosulfide, and mineral salts are adjusted to give a grainy product when the paste slurry is dried on a steam-heated drum dryer. Grains offer the advantage of not being dusty. 

Drum Drvers. For materials in liquid and slurry form. One or several drums dip into the liquid or slurry and thus coat the heated drums. The drum temperature is controlled to effect drying during a port of the rotation of the drum from which the dried material is removed by knife prior to dipping one again into the liquid material. 

Furnaces in use possess different sizes inner diameter between 300 and 750 mm and heated drum lengfli fix)m 3000 to 8000 mm. The most common equipment has an inner... 

In drum dryers, slurries or pasty feedstocks are dried on the surface of a slowly rotating steam-heated drum. A thin flhn of the paste is applied on the surface in various ways. The dried film is removed (doctored off) once it is dry and is collected as flakes (rather than powder). Figure 23.24... 

Sample Sealing. Half-inch-wide substrate strips were sealed on a heated drum at 120°C using a roller with a 3-kg load weight (7). 

Other flaky chemicals obtained from drum coolers or dryers that have similar properties as those of the fresh DMT can be similarly converted into dense free flowing intermediate products by pelleting, briquetting, or compaction/granulation. Drum dryers feature heated drums that either dip into a bath of suspended particles or are coated by means of axial dispensers with the suspension. As in the case of drum coolers, dry solids are removed from the drum with scrapers and are typically bulky and dusty before suitable agglomeration has taken place. 

Chemical Engineering was just emerging as a special field and continuous fractionation had been in general use for only about 15 years, distillation having been previously carried out in "shell stills" (heated drums). Professor W. K. Lewis of M.I.T. was a... 

Drum-drying the sol is the least preferred procedure but can be used under suitable circumstances. In this method a thin film is applied to the surface of a rotating, heated drum and the dried residue is continuously removed as the drum rotates. This drying process is particularly applicable when the amorphous silica ultimate particles are larger than about 50 nm in average diameter since these larger particles have a smaller tendency to coalesce coalescence tends to be excessive in drum drying. Since rapid and complete removal of free water... 

The drum dryer is commonly used to dry viscous, concentrated solutions, slurries or pastes on rotating steam-heated drums. It can also be used to dry concentrated solutions or slurries that become more viscous or pasty because of flashing or boiling off of moisture or of irreversible thermochemical transformations of their content that occur on their first contact with the hot drum surface. " ... 

The slurry is applied by direct dip coating of the twin drums in the feed tray at the bottom of the dryer (Figure 11.7) or by splash or spray feeders from a feed reservoir at the bottom of the dryer (Figure 11.8) on to the surface of the two steam-heated drums that are counter-rotating away from each other. - The sheet is formed by adhesion on to the drum surface and is held up against gravity by its surface tension. 

Indirectly heated Drum dryers Vacuum dryers Freeze dryers... 

Figure 10.27 Drying carbon fiber with heated drums.

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