5,406
edits
(One intermediate revision by one other user not shown) | |||
Line 6: | Line 6: | ||
* -------------------------------------------------></noinclude> | * -------------------------------------------------></noinclude> | ||
[[File:Direct_Heated_Dryers.jpg|thumb|200px|right|Direct Heated Dryers]] | [[File:Direct_Heated_Dryers.jpg|thumb|200px|right|Direct Heated Dryers]] | ||
The '''Direct Heated Dryers''' follow the direct heating or drying process. This Direct heating and drying refers to combustion products mixing directly with the process environment (typically process solids and a forced “air” stream). Because radiation transfer is rapid, typically at high temperature, and ceases upon reaching a boundary (the outer layer of process matter), it is often undesirable and unnecessary. Therefore, natural and forced convection heat transfer engineering may dominate dryer designs. There are a wide variety of process [[dryers]], [[kilns]], [[calciners]], [[ovens]], etc. that incorporate an even greater range of combinations in forced convection, radiation, and conduction (through the material) heat transfer principles to satisfy the product requirements. | |||
==Function== | |||
In all cases, however, the heat energy supplied to a system must perform the following four tasks: | |||
* Heat the dryer feed to the “light” component’s vaporization temperature. | |||
* | * Vaporize and/or free the liquid/byproducts above the solids’ surface. | ||
* Heat the solids to the final desired temperature, and for the desired duration of time. | |||
* Heat the vapor to the final desired temperature. | |||
* | |||
* | |||
* | |||
edits