This application involves level control for first stage separators, a large pressure vessel into which feeds the fluid from the oil/gas wells. Water and solids (primarily sand) are allowed to settle out of the fluid and the oil and gas are removed from the top of the separator vessel for further processing. The water is removed from the bottom of the vessel and usually re-injected into the formation.
This valve application suffers from the twin evils of sand erosion and cavitation. The CCI Severe Service Choke valve is uniquely suited for this design because the valve trim is made from solid tungsten carbide, and is multi-staged so that cavitation is prevented.
Often a choke valve is placed in these applications because the harder trim (usually tungsten carbide) is believed to resist fluid-borne sand erosion better than conventional control-valve trim. The problem is that traditional choke trims are not usually able to prevent cavitation, and the relatively brittle tungsten carbide material is easily fractured by the energy of the imploding cavitation bubbles, essentially a fatigue-type failure.
One of the largest producers in the North Sea, and a leader in the industry, had tried a variety of control valves and choke valves for first stage separator-level control on one of their offshore platforms. The valve trims would typically last about six weeks,with the all-time record being three months. CCI prepared a proposal and after some time was able to convince the customer to try our Severe Service Choke in this application.
After six months (twice the previous record and four times the typical life) CCI and platform personnel removed the valve for inspection. After the parts were measured and photographed, the valve was re-assembled and returned to service for another eight months. Based on the data collected at the inspection, CCI was able to slightly modify the design in order to achieve a two-year service interval. The valve has recently been re-trimmed with the modified design.
CCI’s customer was pleased enough by the condition of the trim after the inspection, that purchase orders were issued for many more valves and CCI’s Severe Service Choke has been made the de facto standard for this application. In fact, CCI has produced this valve for not only first-stage separators, but also for test separators.
Separator Level Control has been a chronic problem application for many years in the oil and gas industry, particularly where sand is present. CCI’s Severe Service Choke solves this problem and delivers performance and service life that cannot be approached by any other control valve or choke in the world.