Abstract: A method and an apparatus for controlling airflow in a desiccant drying system having a plurality of desiccant beds, in which each desiccant bed is located in a chamber, and multi-position valves can be operated to cause the gas to be dried to flow in a serial manner through a plurality of desiccant bed chambers while another desiccant bed is isolated from the gas flow and undergoing regeneration. Once regenerated, the multi-position valves are repositioned to establish a new serial flow gas path in which the freshly regenerated desiccant bed becomes the final bed in the series, and another bed undergoes regeneration.

Abstract: A vacuum receiver for a pneumatic conveyor for conveying, e.g., plastic pellets, having a receiving vessel with a material inlet, a material outlet and a conveying gas outlet. A first valve member is provided for opening and closing the conveying gas outlet, and a second valve member is provided for opening and closing the material outlet. Both valve members are connected to a common valve shaft and actuated by a single actuator mounted on a vessel lid. The vacuum receiver of the invention has the advantage of affording positive control and sealing of the material discharge valve while at the same time being economical to manufacture and easily cleaned.

Abstract: A method and system for controlling airflow in a desiccant drying system having two desiccant beds. A first diverter valve (14A) communicates with each of the desiccant beds, a regeneration air inlet (22A), and a process air outlet (28A). A second diverter valve (16A) communicates with each of the desiccant beds, a process air inlet, and a regeneration air outlet. A first of the beds is regenerated by moving the first diverter valve to a position which the first bed communicates with the regeneration air inlet and a second of the beds communicates with the process air outlet, and by moving the second diverter valve to a position in which the first bed communicates with the regeneration air outlet and the second bed communicates with the process air inlet. The first bed is subsequently cooled by moving the first diverter valve to an intermediate cooling position in which the second bed communicates with both of the process air outlet and the first bed, and closing the regeneration air inlet.

Abstract: A method and an apparatus for regenerating a moist adsorption medium in a multiple vessel drying system utilize a pulsed control of a purge gas outlet valve during a regeneration phase. Internal heaters are embedded in the desiccant beds. During the regeneration phase of a desiccant bed, the internal heater heats the desiccant to remove the moisture therefrom in the form of water vapor. After the water vapor builds up in the drying vessel for a certain period of time, the purge gas outlet valve is opened for a period of time just long enough to flush the built up water vapor from the vessel, and is then closed again. Accordingly, the amount of purge gas required is minimized, which leads to a higher quality purge, higher overall system drying efficiency, as well as reduced energy requirements.

Abstract: An apparatus for dehumidifying air includes a first air path having a first opening, a second opening, and a first desiccant mass intermediate the first and second opening, a second air path, having a first opening, a second opening, and a second desiccant mass intermediate the first and second opening, and an apparatus for causing air selectively from either the first air path or the second air path to flow to an outlet of the apparatus, wherein the ratio of the weight of each of the desiccant masses to the air flow rate into the apparatus outlet is about 1 pound of desiccant for each 10 to 20 cubic feet per minute of air flow. A controller adjusts regeneration heating times based on detected dew point before switching between air paths and detected temperature after switching air paths.

Abstract: A system for transporting material in particulate form from one of a number of sources to one of a number of processing stations, which system includes source tubes separated from each source by a material control valve, destination tubes leading to each processing station, and a rotary valve connecting source tubes and destination tubes. A pump is connected, by an air line which has a valve corresponding to each processing station, to each destination tube. A controller controls the pump, material control valves, rotary valves, and air valves so as to establish a flow of air from a selected source tube to a selected processing station and enable the introduction of a selected amount of material into a source tube while maintaining the flow of air until the material has reached the processing station. In an alternative embodiment, a flexible hose may be employed to connect a selected source tube and a selected destination tube.

Abstract: A method for drying articles flowing through a drying chamber by introducing heated air into the drying chamber. In normal steady-state operation, the inlet and outlet temperatures of the air are monitored, and the inlet temperature is maintained at a normal operating inlet temperature. When the inlet and outlet temperatures approach each other, a stoppage or reduction of the normal steady-state flow of the articles is indicated, in response to which the inlet temperature is reduced to an energy saving temperature. After the inlet temperature is reduced to the energy saving temperature, monitoring of the inlet and outlet temperatures continues. When the difference between the energy saving inlet temperature and the outlet temperature increases, resumption of the normal steady-state flow of the articles is indicated, and in response thereto the inlet temperature is increased from the energy saving temperature to the normal operating inlet temperature.