GB442611A - Improvements in or relating to apparatus for using adsorbents - Google Patents

Abstract

An adsorbent apparatus, suitable for removing moisture from gases or from liquids such as benzol or lubricating oils, or for removing a gas from a mixture of gases, comprises a container in which is arranged a solid adsorbent, for example, activated <PICT:0442611/III/1> <PICT:0442611/III/2> <PICT:0442611/III/3> in Fig. 1, two towers 11 containing adsorbent material 29 are connected at the top to gas inlet pipes 12 and at the bottom to outlet pipes 13. A three-way valve 15 controls communication between a supply pipe 14 and the two pipes 12. A similar valve 17 is provided connected to a discharge pipe 16. The pipes 12 may also be connected by a three-way valve 20 to a pipe 18 connected to a supply of wash gas whereby saturated adsorbent may be reactivated. Embedded in the adsorbent in each tower is a hollow resistance wire 30 spirally arranged and provided with terminals 32 for connection to a source of electric current. The upper end of the wire is adapted to be connected to a fluid supply pipe 33 provided with a control valve 35. The lower end of the wire leads to a discharge pipe 37. A thermo-couple 38 adapted to control the heating of the adsorbent extends through the wall of each tower. The gas to be dried is passed downwardly through one tower until the adsorbent is saturated. The valves 15, 17 are then operated to connect the gas to the other tower and valves 20, 23 are operated to direct wash gas through the tower containing the saturated adsorbent which is at the same time heated by current through the resistance 30. The adsorbent is thus re-activated and when re-activation is completed, the wash gas is shut off and the current through the tube 30 switched off. The tower is then cooled by cooling medium passed through the tube. The tube may be provided with metal radiating spines 38<1>, discs or fins to facilitate conduction of heat. The wash gas may be preheated before it reaches the adsorbent material, by the provision of electric heating elements at the upper end of the tower, as shown in Fig. 4. These elements comprise spaced resistance plates 41 each of which is slotted to provide a tortuous path for electric current. The tube 30 may be arranged so that the turns are larger alumina or an adsorbent gel, the adsorbent being adapted to be heated by an electric heating element of tubular form which is embedded therein. In the construction shown or closer together at the top of the tower so that a better heating effect is obtained there than at the bottom of the tower. To prevent precipitated moisture from the wash gas being subsequently absorbed by the dried gases, the tower is provided with an outlet 44 for dried gas and an outlet 45 for wash gas. Above the outlet 45 is a perforated plate 46 supporting a layer of adsorbent material 47, which adsorbs any precipitated moisture. Electric heating elements 48, 48<1> may be arranged at the lower end of the tower to reduce precipitation. The tube 30 may be replaced by a number of tubes providing separate zone control. A portion of the dried gas from one tower may be circulated through another tower as a wash gas during the final stages of re-activation. Fig. 11 shows a method of interconnecting the gas-control valves and electric control switch for simultaneous operation in a system employing two towers. Four-way valves 15<1>, 17<1>, 50 are arranged as shown, the valves 15<1>, 17<1> being connected by a rod 56 to the switch S controlling current to the heating coils. A valve 52 is provided in a byepass pipe 51 and a valve 53 is connected between four-way valves 15<1> and 50. In the position shown, with valve 53 open and valve 52 closed, gas to be dried flows from pipe 14 through valve 15 and down through adsorber A, passing out through valve 17<1> to discharge pipe 16<1>. Wash gas enters valve 50 through pipe 18<1> and passing through valve 15 flows down through adsorber B and through valves 17<1>, 50 to the discharge pipe 21<1>. By rotation of the valve 50 through a right angle, the wash gas may be sent upwardly through the adsorber. The switch S during this time is set to allow current to pass through the coil 30 of the adsorber B. On operation of the lever 56 to turn the valves 15<1>, 17<1> through a right angle, the wash gas is caused to flow through the adsorber A, and the coil 30 therein is switched into circuit while the circuit through the coil of the adsorber B is opened.