Site visit to Slurry Flow Laboratory, FloCEP Pty Ltd
Slurry Flow Laboratory
Scott Doig, Director FloCEP Pty Ltd
L to R Geoff Williams, Scott Doig.
FloCEP® Pty Ltd has developed a suite of products that remedy problems caused by segregation in slurries and other multiphase flows, including
oil and gas. The highlight of the visit was a demonstration rig set up for visualisation of slurry flow phenomena that are normally hidden from view
inside pipes. However, the facilities on display included extensive capability for in-house design and manufacture of customised pilot plants, two
of which were on currently in operation.
Scott Doig explained that his business had started in refrigeration and air conditioning, then the manufacture of specialised industrial refrigeration
equipment. From this he had moved into customised laboratory and pilot plant equipment, notably for the alumina industry. This experience, gained over
nearly three decades, has given him exceptional hands-on understanding of dealing with multiphase flows, including slurries subject to flashing. He
also became aware of the operational impacts that can arise at certain critical points in flow circuits as a result of the natural tendency for such
flows to segregate. This gravitational segregation occurs due to the differing densities of the component phases, and is exacerbated by centrifugal
force when the flow changes direction, as happens in pipe bends.
FloCEP’s developments are based on its PROmotion® technology platform. The key to the technology is the way it re-mixes the phases so that the flow is made pseudo-homogenous just before the point where segregation would otherwise lead to problems. This is achieved with the FLOprep™ device, which uses the kinetic energy of the flow to mix the phases. This device has no moving parts does not require any additional energy input, shows no significant wear, and no discernible increase in pressure drop.
The first product Scott described is the MAXbend® (maximised life) bend for slurry pipes, the patent for which covers the FLOprep device. He demonstrated its effectiveness with photographs of the inlet bend to an alumina digester flash tank. The original 4mm weld-overlaid bend had a life of approximately six months due to severe internal erosion from the flashing slurry. The replacement MAXbend unit, which was manufactured as bolt-in replacement, has been in place for four years and is expected to achieve a life of six to eight years. By re-mixing the slurry into the flow, avoiding the concentration of solid particles on the outer radius of the bend, abrasion is virtually eliminated, even to the extent that a thin layer of protective scale is maintained.
The second product Scott demonstrated is the FLOdistributorTM, which is covered by a separate patent. This is used in conjunction with the FLOprep device to split the re-mixed flow evenly so that all outlet flows are the same, not just in total flow rate, but with equal density. That is, the flow rates of all components are equal in all outlets. Failure to split slurries equally is not necessarily obvious to the eye, but has serious consequences in applications such as hydrocyclone clusters, which only work optimally when all units receive identical flows of both liquids and solids.
Scott showed the group the effects of segregation and how it can be controlled with PROmotion technologies, by means of a demonstration rig constructed with sections of glass pipe. Slurry segregation effects were made visible in horizontal, vertical and sloping sections, together with the effects of re-mixing with FLOprep devices. Changes in distribution were demonstrated by contrasting a conventional bottom-fed distributor well with a FLOdistributor.
Scott also gave visitors the opportunity to inspect a full-scale slurry distributor which had been taken back for inspection after 3.5 years’ use in an operating gold milling plant. As well as performing exceptionally well in its role as a distributor, it showed very little wear, despite the passage of more than 30 million tonnes of highly abrasive dense slurry. The first immediate benefit for the operators of the gold plant has been complete elimination of unplanned interventions to the cyclones; these interventions had previously averaged one every three days. The second benefit has arisen from the tighter control of milling made possible by the optimal cyclone operation resulting from even distribution. These improvements, which have extended from throughput, to recovery and to tailings disposal, have had a much greater financial impact than had been anticipated.
Another key feature of the FLOdistributor is its ability to distribute multiphase flows evenly regardless of the number of outlets that are open at any time. This ability to maintain uniform phase concentrations as downstream units are brought on or taken off line is of particular interest to the oil & gas industry. A customised pilot plant (not demonstrated) was installed in the facility for Shell Australia to prove the use of the FLOdistributor in flow manifolds that would be installed on the seabed.
Scott also referred to other applications, including flow sampling and chemical injection, in which there are great benefits to be gained from the PROmotion technology platform.
Perth Branch is very appreciative to FloCEP of this opportunity to gain insights into remarkable new technology, and for the company’s generosity in providing hospitality to visitors.
MAXbend wear comparison