GB810657A - Improvements in dehydration and process of gas streams - Google Patents

Abstract

810,657. Drying gases. PARKS, A. S. Jan. 2, 1956, No. 110/56. Class 34(1) Gases containing hydrocarbon liquids and water are dried in an apparatus comprising two desiccant packs one of which is regenerated by a hot gaseous stream whilst the other is in service. As shown, a vessel 10. Fig. 1, has two desiccant packs of solid adsorbent and gas to be dried enters the vessel through pipe 17 and leaves through one of the pipes 18, 19 depending upon which pair of motor type valves 54, 42, or 53, 43, is closed. The hot, dried gas passes to a pressure reduction vessel 56 through a heat exchanger 55. In the vessel 56 the temperature fall of the gas results in further drying, any remaining liquid fractions condensing and passing through a pipe controlled by a level controller 60. The cold, dry gas is then heated by passage through heat exchangers 55 and 36 via piping 58, 59. The hot gaseous desiccant-regenerating stream is formed by tapping the incoming wet gas stream at 38 such that gas flows through piping 39 and a fixed orifice 44 to a heater 40. The heater is fired by a burner 41 controlled by a thermostat 41a in the hot gas outlet pipe 39a. A substantially constant volume of regenerating gas is tapped at 38 by the employment of the fixed orifice 44 the differential pressure across which actuates a rate controller 45. The latter operates a motor valve 37 controlling the wet gas input to the drying vessel 10 to maintain a desired back pressure in the tapping chamber 38. The fuel supply to the heater 40 is through a motor valve 48. A time cycle controller and burner shut-off mechanism 50 controls the drying apparatus the mechanism opening and closing the valve pairs 54, 42, and 53, 43, on a predetermined time cycle base and effecting the necessary consequential control of the burner 41. The vessel 10, Fig. 2, comprises coalescing packs 32, 33, and desiccant packs 34, 35. In operation, with the pack 34 in service the valves 54, 42, and 53, 43, are "closed" and "open" respectively. Hot regenerating gas enters through the pipe 19 and, after drying the pack 35, mixes with the incoming wet gas in a chamber 20. This chamber contains a baffle 21 facing the inlet pipe 17 which aids separation and precipitation of water and liquid hydrocarbons from the wet gases. These liquids together with the water and hydrocarbons falling out of the regenerating gas due to its sudden drop in temperature on mixing with the wet gases, drop into a housing 23 having discharge pipes 24, 28 for water and liquid hydrocarbons respectively. Each pipe has suitable floatcontrolled level controllers 25, 29. The liquid hydrocarbons discharging through pipe 28 may be directed either to the common outlet pipe 20a through pipe 28a or to the vessel 56 through pipe 28b. In a modified vessel 10, Fig. 4, the hot regenerating gas stream is cooled before mixing with the wet gases heat exchangers 70, 71, being used for this purpose and so arranged and connected that the cooling medium is the cool dry gas which is discharging from the drying cycle of the vessel. Fig. 5 shows an apparatus in which the coalescing packs 32, 33, are mounted in a vessel 10a but the desiccant packs 34, 35, are in vertical towers 34a, 35a. A housing 22a with one discharge pipe and a level controller 25a replaces the housing 23.