Chromatography system with tilt-prevention structure and associated process

Abstract

Chromatography apparatus and methods are described, especially for expanded bed adsorption. A column tube has a process fluid input device at the bottom and a movable piston in the top. The piston is enclosed in the column by a cover plate. The piston body has an inflatable seal, and is connected by a frame to a contact ring which carries another inflatable member to contact the tube wall. Process fluid leaves the operating volume through an opening of the piston and flexible hose, through the enclosed space and out through the cover plate. The space above the piston can be pressurised to control piston movement. The contact ring maintains piston alignment. The inflatable seals are used to fix the piston in position, allow it to slide or allow washing. The piston outlet may include a vortex-inhibitor. Bed and piston levels may be monitored by ultrasound sensors.

1 . A chromatography apparatus comprising:
 a column tube having a tube axis defining an axial direction of the apparatus;   first and second end cells which close off the column tube, defining between them an operating volume in the column tube;   at least one of the end cells is a movable piston, slidably movable inside the column tube in the axial direction thereof and comprising a peripheral operating seal to seal against the inside of the column tube;   said movable piston comprising a piston body comprising the operating seal; and   a tilt-prevention structure projecting axially from the piston body and connected to be rigidly axially aligned therewith, wherein the tilt-prevention structure comprising a circumferentially-distributed contact structure which engages around the interior of the column tube at an axial spacing from the operating seal.   
     
     
         2 . The chromatography apparatus of  claim 1  in which said movable piston is free of rigid structure passing through any fixed column end structure of the apparatus. 
     
     
         3 . The chromatography apparatus of  claim 1  in which said contact structure is annular and engages continuously around the column tube interior. 
     
     
         4 . The chromatography apparatus of  claim 1  in which the contact structure is radially movable relative to the tilt-prevention structure; and
 the movable piston comprises a contact structure actuating mechanism operable to urge the contact structure radially outwardly against the column tube interior and/or to retract it to a radially retracted condition or position. 
 
     
     
         5 . The chromatography apparatus of  claim 1  comprising an outer closure of the column tube, and in which the movable piston, column tube and outer closure define a pneumatic space outside the movable piston, separated from the operating column, and
 a pressured gas supply for supplying pressurised gas into the pneumatic space to act on the movable piston. 
 
     
     
         6 . The chromatography apparatus of  claim 1  in which the contact structure comprises an elastomeric ring. 
     
     
         7 . The chromatography apparatus of  claim 1  in which the engagement of the contact structure with the column tube interior is around a single annulus at a constant axial spacing from the operating seal. 
     
     
         8 . The chromatography apparatus of  claim 1  in which the tilt-prevention structure is an open structure comprising any of rods, legs and struts with intervening spacing. 
     
     
         9 . The chromatography apparatus of  claim 1  in which an axial extent of the contact structure, said axial extent being the maximum axial distance reached by the contact structure from the axial position of the operating seal, is at least 25% of a diameter of the movable piston. 
     
     
         10 . The chromatography apparatus of  claim 1  in which the operating seal comprises an elastomer ring in a peripheral channel of a piston body. 
     
     
         11 . The chromatography apparatus of  claim 1  comprising a pneumatic mechanism for the radial advance or retraction of the operating seal. 
     
     
         12 . The chromatography apparatus of  claim 1  comprising sensors to detect the axial position of the movable piston in the column tube. 
     
     
         13 . The chromatography apparatus of  claim 1  in which the movable piston has a central process fluid outlet and comprises a vortex-inhibiting structure at said process fluid outlet, the vortex-inhibiting structure comprising one or more divider, partition or slot-defining elements. 
     
     
         14 . A chromatography apparatus comprising:
 a column tube having an inside surface and a tube axis defining an axial direction of the apparatus;   a movable piston, slidably movable inside the column tube in the axial direction and comprising a peripheral operating seal to seal against the inside surface of the column tube;   said movable piston having a diameter and comprising a piston comprising the peripheral operating seal;   a tilt-prevention structure projecting axially from the piston body, the tilt-prevention structure comprising an annular contact structure which engages around the inside surface of the column tube at an axial spacing from the operating seal which is at least 25 percent of the diameter of the movable piston; and   an open frame structure connecting the annular contact structure rigidly to the piston body.   
     
     
         15 . The chromatography apparatus of  claim 14  in which the movable piston has a central process fluid outlet. 
     
     
         16 . The chromatography apparatus of  claim 14  comprising a pneumatically-actuated mechanism to urge the contact structure radially outwardly against the inside surface of the column tube. 
     
     
         17 . The chromatography apparatus of  claim 14  in which the contact structure comprises a polymeric ring to contact the inside surface of the column tube. 
     
     
         18 . A chromatography apparatus comprising:
 a column tube having a tube axis defining an axial direction of the apparatus;   a fixed outer end closure of the column tube;   an end cell comprising a piston slidably movable inside the column tube in the axial direction thereof and comprising a peripheral operating seal to seal against the inside of the column tube, said movable piston being free of rigid structure passing through the fixed outer end closure, and whereby the movable piston, column, tube and outer end closure define a pneumatic space in the column tube; and   a pressurised gas supply inlet for the supply of pressurised gas into the pneumatic space to act on the movable piston.   
     
     
         19 . The chromatography apparatus of  claim 18  in which the movable piston has a process fluid outlet, a sealed connector is provided extending through the column tube or through said outer end closure, and a flexible conduit is connected at one end to the process fluid outlet and at the other end to the sealed connector. 
     
     
         20 . The chromatography apparatus of  claim 18  in which the operating seal comprises an elastomer ring and the apparatus comprises a pneumatic mechanism operable to advance or retract the operating seal radially relative to the piston, so as either to urge the operating seal outwardly against the inside of the column tube or to retract it to a radially retracted condition. 
     
     
         21 . A chromatography process carried out with the chromatography apparatus of  claim 1 , the process comprising:
 providing a bed of particulate medium in the operating volume;   adjusting the position of the movable piston in the axial direction towards the bed of particulate medium; and   passing a process fluid through the bed of particulate medium.