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The IOR Multi-chamber Distillation Column

Conventional oil refinery distillation columns typically range in height from 12 metres to 30 metres and must be designed to withstand wind loading and earthquake movement.  Often the structural load stress design criteria determines the required wall thickness of a vertical vessel and not the containment criteria for its internal operating pressure.  Costly foundation or support systems are also needed to support tall towers.  Tall columns are also hazardous as they require personnel to work at heights during its installation and during on-going maintenance activities.  Fire-fighting is also problematic.  

Offshore processing of crude oil and gas on FPSO vessels or fixed platform will now become more practicable with a low height geometry.  A low height tower significantly reduces the forces on the column and its internal liquids caused by ship heaving and rolling.  The safety hazards on ship-borne installations associated with column height and overhead pipework are also reduced.

IOR’s patented multi-chamber distillation column allows the tower height to be reduced by increasing its diameter.  For the smaller tower volume, that is the main application for the IOR technology, metal thickness of the tower shell ends up no thicker than of a conventional tower vessel, since the wind load and earthquake stresses are markedly reduced.  However the overall amount of material used in the vessel construction is much less for the same internal column volume.  Thus a conventional tower with a height of 20 metres can be reduced to around 4 meters in height with the attendant benefits of safer erection and operation and simpler fire-fighting, vessel insulation, foundation supports and less steel alloy material and piping.  IOR’s novel approach represents a sea-change in design practice for smaller distillation towers used in the petroleum, petrochemical and pharmaceutical industries.    

IOR’s patented fractionation tower design achieves its low height containment pressure vessel by staging the distillation process through a series of internal sub-chambers.  Such a staged fractionating process can be achieved by using vapour-powered fluid circulating devices.  These simple devices provide self-modulating liquid flows to eliminate the need for level controls.  They utilise a re-vapourised slip-stream of a product from the process, as the power fluid.  Alternatively overhead condensers can create a descending fractionated liquid steam to flow into the next stage where the provision of additional heat begins creates the further stage of distillation.   

Basically the IOR patented vessel is equivalent to multiple short distillation columns mounted inside one large diameter pressure containment shell.  The internal segment distillation chambers can then be constructed of thin alloy, as these internal chambers do not bear the full process pressure differentials.  Because each segmented chamber forms a sub-set of the total distillation process, multiple intermediate streams, (ie one liquid stream from each segment), can be drawn as intermediate products, greatly increasing the versatility of the process.  

Furthermore, such side streams have less exposure to       "pass-through" light products compared to conventional towers fitted with side-draw product trays. The extent of the subsequent stripping process to remove the light product contamination in the side-draw products is therefore reduced and in some cases even eliminated. 

The height of a conventional tower is determined by the boiling range of the input stream to be processed and the desired boiling range or cut, of the various output products.  Once installed, the conventional tower cannot be later modified to produce narrower products cuts for the same input feed.  In the case of IOR’s patented multi-chamber distillation tower, narrower product cuts can be achieved at a later date by simply retrofitting a second tower in series with the original tower.  This is equivalent to extending the height of a conventional tower.   

In proving its multi-chamber design, IOR successfully found ways to fit conventional ancillary equipment (sight glasses, PSVs, thermocouples etc) to the unconventional column geometry.  In conventional column designs such devices penetrate the pressure shell.  In the IOR multi-chamber design such direct penetration was not possible.  The pressure vessel design is kept mechanically simple, while still allowing simple access to internal chambers and associated internal interconnecting piping and instrumentation.  

An installed plant using dual IOR Multi-Chamber Distillation Columns and processing 3,500 litres per hour of crude oil into multiple product cuts.

Contact IOR for further information or licensing inquiries.