Hayden P Gildersleeve

US Patent:

41792653, Dec 18, 1979

Filed:

Oct 17, 1977

Appl. No.:

5/842397

Inventors:

Hayden P. Gildersleeve - Colorado Springs CO

Assignee:

Holly Sugar Corporation - Colorado Springs CO

International Classification:

F27B 720
F27D 1900

US Classification:

432 36

Abstract:

The pressure of heated gases supplied by a furnace to an induced draft, rotating drum drier, through which the material being dried is moved primarily by the heated gases, is compared with the pressure of gases discharging from the drum, and the differential between these pressures is used in controlling the induced draft of the drum by decreasing the draft upon an increase in differential pressure and increasing the draft upon a decrease in differential pressure. The differential in pressure may be maintained at a value on the order of 1. 2 to 1. 6 inches H. sub. 2 O, depending on the installation. The induced draft may be controlled at a damper between a discharge chamber for the furnace and an induced draft fan, through an electro-hydraulic actuator acting through a lever and a rod, the lever being manually settable when automatic operation is not used. The signal for the actuator is produced by a load responsive control device to which a signal, corresponding to the differential pressure, is supplied from a pressure responsive transmitter, to which is connected both a pressure pipe extending from the furnace and a pressure pipe extending from the drum discharge chamber. The furnace pressure is also fed to an additional pressure responsive transmitter, for producing a signal proportional to the furnace pressure for transmittal to an override control device, which compares the signal with a preselected minimum furnace pressure.