Patent GB-910059-A (GB)
Title: Improvements in and relating to the pumping-off of gases and vapours by sorption
IPC: H01J9/38
Filed: 1960-11-24
Abstract: 910,059. Obtaining high vacua. BALZERS PATENT-UND-LIZENZ-ANSTALT. Nov. 24, 1960 [Dec. 9, 1959], No. 40414/60. Class 8(1). In a getter pump for pumping off gases and/or vapours by means of a loose granular getter which is led into the vessel to be pumped out and after having been loaded with gases and/or vapours is led out of the vessel. The getter is continuously sluiced into the vessel to be evacuated and continuously sluiced out of it after it has absorbed gas and/or vapour, after which.it is regenerated by heating and returned to the vessel to be evacuated. It is cooled before and/or after regeneration. The regeneration may take place in a pre vacuum. The getter absorbs the gas and/or vapour by adsorption or by chemical action. The getter is moved, by a vibratory conveyer or in some circumstances by a conventional conveyer. The container for the getter extends from the inlet point to the outlet point. At least one sluice means is provided with cooling means. The sluice means may have inclined tubes completely filled with the getter material passing through them by gravity. Preferably a regenerator is placed between the outlet sluice and the inlet sluice, conveyer means returning the getter from the outlet sluice through the regenerator to the inlet sluice. The regenerator and conveyer means are outside the vessel. At least two getter pump stages may be arranged in series each having a sorption zone and a regeneration zone. The regeneration zone of each stage communicates with the sorption zone of the next stage except the regeneration zone of the last stage which is in communication with an external pre vacuum source. Preferably an inverted hollow cone is arranged inside the vessel, Fig. 2, and connected to it by resilient sealing membrane 23 and divided into compartments by disc partitions 26, 27 having small annular gaps around their circumferences, annular heating and annular cooling means 24, 25 being arranged alternately around the cone forming regenerating and sorption zones respectively. The heating means is formed by electric coils and the cooling means by pipes. The cone forms a helical vibratory conveyer conveying the getter upwards from the apex to the base of the cone, the annular gaps forming sluice means and inclined return tubes being provided scooping up at one end of a pumping zone and returning to the regenerating zone by gravity. The vacuum pump is connected to the apex of the cone. In Fig. 1 the getter is supplied through tube 2 from storage tank 12 and flows over an inclined wall which is cooled by cooling pipes 4 then through a tube 5 to the lower end of a regenerator 6 which contains a vibratory upward conveyer track 8 heated by an electrical heating coil 7 and vibrated by an electro mechanical vibrator, overflows at the top 11 and is returned via tank 12 to the vessel to be evacuated. Valves 13, 14 shut off this vessel but may be omitted for continuous operation. Tubes 2, 5 may have cooling means. The getter may be silica gel, zeolites, aluminium oxides, activated carbon, metal powders. Ti or Zr may be used for hydrogen gas, water vapour, oxygen nitrogen. The device can be used for the purifying of gases, even under normal pressure. In this case the device acts as a pump only for those gas components which are gettered. For the achievement of especially high vacua put the regeneration side under a preliminary vacuum by a separate pump which may be connected at 15 or to arrange several pumps in series. In a second embodiment, Fig. 2, a casing 21, 22 the preliminary vacuum pump is connected to pipe 31 in addition to the main vacuum pump. The getter material is gradually moved from the apex to the base of the cone. Pipes 35, 40 return the getter from each cooling zone to each heating zone. There may be more than two gettering stages arranged in series. The vibratory conveyer track may be a helical groove at the inside of a cylinder. Other known conveyer means may be used in the regeneration zone even those which are conveyer belts. If the regeneration zone is dispensed with, the getter is passed from a container into the vessel to -be evacuated and after acting as a getter it is removed and collected in another container which is sealed, e.g. by the getter itself, from the vessel to be evacuated. If some gases e.g. noble gases cannot be gettered, a preliminary pump is provided. The gettered gases when released in the regeneration stage cannot return to the vacuum vessel since the getter seals the annular gaps.