Apparatus and method for vacuum drying
AssigneeAltos Engineering, Inc.
InventorCharles S. Leech, Jr.
Life of this patent
Estimating the term…
Abstract
An article is dried in a vacuum and sublimation is prevented by controlling both the heat applied to the article and the heat lost through evaporation. The article is placed in a vacuum chamber having a plurality of infrared lamps disposed around the interior of the chamber and the chamber is heated to a predetermined temperature prior to evacuation. Heat loss is controlled by maintaining the pressure above approximately 5 torr, which controls the rate of evaporation. The drying cycle also cleans the article.
Claims13
A process for removing a large amount of liquid water from an article under vacuum without sublimation, said process comprising the steps of:
- placing said article in a vacuum chamber;
- maintaining the temperature of said article above 0.degree. C. by evacuating said chamber while heating said article to cause said water to evaporate from said article;
- and
- controlling the rate of evaporation of said water by maintaining the pressure within said chamber above a predetermined, reduced pressure while said water converts from the liquid phase to the vapor phase.
Apparatus for removing a large amount of liquid water from articles under vacuum without freezing said water, said apparatus comprising:
- an evacuable chamber for containing said articles;
- a plurality of heaters within said chamber;
- a vacuum pump connected to said chamber for reducing the pressure within said chamber to a predetermined pressure while water vapor is evolving from said articles;
- a control system for maintaining the temperature of said article above 0.degree. C.;
- and
- a valve connecting said pump to said chamber, said valve supplying a predetermined amount of air to said pump for preventing said pump from reducing the pressure in said chamber below approximately 5 torr while water vapor is evolving from said articles.
Apparatus for removing a large amount of liquid water from articles under vacuum without freezing said water, said apparatus comprising:
- an evacuable chamber for containing said articles;
- a plurality of heaters within said chamber;
- a vacuum pump connected to said chamber for reducing the pressure within said chamber to a predetermined pressure while water vapor is evolving from said articles;
- and
- a control system for maintaining the temperature of said article above 0.degree. C.;
- wherein said control system includes
- a pressure sensor for producing an electrical signal
- indicative of the pressure within said chamber;
- a temperature sensor for producing an electrical signal indicative of the temperature within said chamber;
- a vacuum pump connected to said chamber for evacuating said chamber;
- a solenoid valve connected between said vacuum pump and said chamber;
- a heat control circuit connected to said heaters and to said temperature sensor for heating said chamber and maintaining said chamber at a predetermined temperature;
- and
- a vacuum control circuit connected to said pressure sensor and to said solenoid valve for terminating the evacuation of said chamber when the pressure in said chamber falls below 5 torr.
A process for removing a large amount of liquid water from an article by evaporation without sublimation, said process comprising the steps of:
- placing said article in a vacuum chamber;
- pumping said chamber to reduce the pressure within said chamber;
- supplying heat of vaporization to said article to produce water vapor and to increase the pressure within said chamber;
- continuing pumping and supplying heat until the pressure within said chamber drops below 5 torr;
- and
- terminating pumping and supplying heat when said pressure drops below 5 torr;
- whereby the temperature of said article remains above 0.degree. C. during the entire time said water is being evaporated.
Dependencies are inferred from the claim text.