Patent ID: 6729039
Filing Date: 2004-05-04
Classification: B01D,F24F,F26B

Abstract:
A method for controlling airflow in a desiccant drying system comprising:first and second desiccant beds, a first diverter valve communicating with each of said desiccant beds, a regeneration air inlet, and a process air outlet; a second diverter valve communicating with each of said desiccant beds, a process air inlet, and a regeneration air outlet; a first regeneration air control valve interposed between said regeneration air inlet and said first diverter valve; a second regeneration air control valve interposed between second diverter valve and said regeneration air outlet; at least one heater for heating regeneration air prior to passage of the regeneration air through the desiccant bed; a first cooling bleed stream line connected between said process air inlet and said second regeneration air control valve; and a second cooling bleed stream line leading from said first regeneration air control valve back to the process air stream; said method comprising the steps of: (a) regenerating a first of said beds by moving said first diverter valve to a position in which said first desiccant bed communicates with said regeneration air inlet and said second desiccant bed communicates with said process air outlet, and moving said second diverter valve to a position in which said first desiccant bed communicates with said regeneration air outlet and said second desiccant bed communicates with said process air inlet; (b) subsequently cooling said first bed by moving said second regeneration air control valve to a position in which a process air bleed stream is passed from said process air inlet through first cooling bleed stream line, said second regeneration air control valve and said second diverter valve to said first desiccant bed to extract heat from said first desiccant bed, and moving said first regeneration air control valve to a position in which said process air bleed stream after passing through said first bed is passed through said first diverter valve, and said first regeneration air control valve and returned to the process air stream.