Before oil can be sold or used in production, it must go through a separation process to remove any impurities. A separator level control system can involve several stages of separation to ensure that the oil is fit for purpose. The below diagram shows a typical process for removing such impurities.
As far back as 1974, we supplied a number of control valves for a separator level control system. The diagram above shows a schematic of the system. The original trim was an HFD cage-guided design with an operating pressure drop of 100 bar (1450psi).
Several years later in the early 1980s, the client introduced water injection, resulting in the fluid being contaminated with sand. Within two weeks of operation the valve trim was severely eroded due to the excess sand contamination. This image shows the extent of the damage caused.
INNOVATIVE PATENTED SOLUTION
Over the next two years we developed the LCV trim design. This included various improvements to allow the valve to withstand the erosive nature of the medium. These included the introduction of a dead-band, sacrificial plug nose, shrouded seat face arrangement and solid tungsten carbide for the main trim control elements.
This diagram shows the new design features. The key features of this design were patented and still form the basis of our current severe service choke trim design as well as being an option within the globe control valve product range. The trim design used tungsten carbide resulting in a significantly lower level of erosion to the sacrificial elements even after two years of operation.
STANDING THE TEST OF TIME
This image shows some inevitable signs of wear and tear. However even after two years the severe damage which put their previous valve out of service in just two weeks, had been completely avoided.