Process and apparatus for treating gases and vapours with adsorbents

摘要

In a process for treating gases or vapours with an absorbent, e.g. removing water and condensible hydrocarbons from natural gas by treating with silica gel, the wet natural gas is passed through a number of absorbent zones under pressure and a heated gas is cycled through each zone in succession to remove the absorbed water and condensed hydrocarbons, and to re-activate the absorbent zones, whereby each zone becomes first an absorbent zone and is then re-activated. The heated gas may be the dried natural gas produced, or another neutral gas. A suitable apparatus comprises a closed pressure chamber 20, Fig. 3, provided with a number of absorber chambers 31 mounted between upper and lower platforms 63 attached to central annular plates 57, 66 secured to an axis 26. The absorber chambers are connected at each end through flexible pipes 38, 39 to a manifold distributing chamber 33, closed by a spring pressed disc valve member 35. Four gas inlets are provided at the top of the chamber 20 (41, 42 shown) and four outlets at the bottom (45, 46). These gas ducts are connected to the fixed manifold distributing chamber which is divided by partitions into four chambers each provided with an opening 74 which may be brought into communication with flexible pipe openings mounted in the rotating member 35. The adsorbent chambers, Fig. 9, comprise a closed tubular shell 91, having the side walls tapered, and provided with gas inlet and outlet 81, and a removable cover plate 93. The adsorbent 106 contained in a removable member 95, consists of two concentric tubular screens 102, 103 of which the inner is provided with a conical baffle member 113. A cylindrical fin 111 mounted on the top cap member projects downwards into the body of the silica gel, and prevents gas flowing directly into the outlet. The tapering side walls and conical member ensure that the velocity of the gas upstream and downstream is substantially the same, and the gas is uniformly distributed under a constant static head. The absorbent chambers may be removed through a gas-tight enclosure 115 mounted on the pressure chamber 20. In operation, wet natural gas under a pressure of 500/1000 lb. and at 60 DEG to 95 DEG F. is admitted through an inlet 41 at the top of the chamber, and passes through flexible pipe 38 and downwards through a group of absorbers 31 in communication through disc valve 35 to the manifold. The gas now partially dried passes through outlet pipes 39, 45 through an inter-cooler to inlet 42 and through a second group of absorbers 31 where the remaining moisture is absorbed. A part of the dry natural gas is tapped off, heated to 300 DEG to 600 DEG F. and passed upwards through the saturated silica gel in the absorbers 31 to re-activate the absorber and remove water and light hydrocarbons which are then condensed and separated. The stripped gas is then recirculated by a blower through the heater and used again as an activating gas or in a final purging treatment. Other gases may be used as the activating or purging medium. By rotating the series of absorbers, they are used in the first and second stages as absorbers, and in the third and fourth stages they are reactivated and purged. Specification 652,835 is referred to.