Diamond Systems Tritan Guia de Resolução de Problemas descarregar pdf (Página 27)

Tray dryers. These dryers can be used only if they are supplied

with air dried by a good desiccant bed system. Tray dryers with

heating only (and no desiccant) do not adequately dry the pellets.

Good dryers for production typically include either rotating

beds or other means to keep continuous airﬂow through a freshly

regenerated bed while other beds are regenerated off-line. Tray

dryers with manually charged single beds are also generally not

recommended for continuous production operations.

Conditions

The recommended drying time and temperature are listed on

the data sheet for each Eastman

™

polymer.

Elements necessary for proper drying

Drying temperature. Air circulating through the hopper is

heated by the process heater or afterheater. The air temperature

should be measured at the inlet to the hopper and controlled

at the recommended drying temperature for a given polymer.

Exceeding this temperature will cause premature softening

or melting of pellets to the point of sticking together, causing

failure to feed freely to the bottom of the dryer for unloading.

Drying at temperatures below the recommended setpoint will

result in inadequate drying. When the controlling thermocouple

is located away from the hopper, the setpoint may need to be

raised to offset heat loss from the air during transport to maintain

the desired hopper inlet temperature. Check the temperature

over several cycles of the process heater. If the actual

temperature overshoots the setpoint, adjust the setpoint

accordingly to avoid overriding temperatures. Drying temperature

should be held constant within ±3°C (±5°F). Insulated supply

hoses and hoppers make drying much more effective and save

energy costs.

It is also important to maintain air temperature (at least 205°C

[400°F]) in the regeneration loop of the dryer. The regeneration

loop is a separate system from the process loop, so the presence

of hot air in the process loop does not guarantee that the

regeneration loop is functioning.

Figure 31 Typical desiccant dryer

Regeneration

blower

Regeneration

air ﬁlter

Regeneration

heater

Regeneration

temperature

control

Process

heater

Desiccant

carousel

Aftercooler

Return

air

ﬁlter

Return

air

ﬁlter

Process

temperature

monitor and

control

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 43 44

Comentários a estes Manuais

Sem comentários

Diamond Systems Tritan Guia de Resolução de Problemas Página 27

Comentários a estes Manuais

Manuais e produtos relacionados com Quadros elétricos Diamond Systems Tritan