The application of disc centrifuges in the dewatering of heavy oil emulsions does face a number of problems, which mainly stem from the complexity of heavy oil emulsions and the working principle of disc centrifuges and their operating characteristics. These problems are analyzed in detail as follows.
Working Principle of Disc Centrifuge
Disk centrifuge utilizes the different settling speeds of liquid-phase and solid-phase substances of different densities under the action of centrifugal force field to realize effective separation. Its drum is mounted on the upper end of the vertical shaft and rotates at high speed driven by an electric motor through a transmission device. There is a small gap between the disc and the disc, the suspension (or emulsion) is added to the drum by the feeding tube located in the center of the drum, and under the action of centrifugal force, the components of different densities are rapidly settled and stratified, thus realizing liquid-solid (liquid-liquid) separation.
Problems in heavy oil emulsion dewatering
Emergency machine seal water is not reasonably designed:
Disc centrifuge in high-speed operation, must be cooled with cooling water for machine seal cooling, otherwise it may burn out in a short time.
If the emergency machine seal water design is unreasonable, such as the booster pump outlet pressure, power, and directly hooked up to the positive power circuit, once the oil field power loss, the centrifuge may burn out due to lack of cooling water.
High-speed shear in centrifuges leads to high emulsification of some crude oil:
Disc centrifuges generate high-speed shear during high-speed rotation, which may lead to high emulsification of some crude oils and increase the difficulty of dewatering.
On-site sampling found that the O/W (oil/water) ratio of crude oil treated by the centrifuge may be as high as a certain value, indicating that the high-speed shear effect of the centrifuge exacerbates the emulsification of crude oil.
Centrifuges require high quality feed:
When processing sandy crude oil, disc centrifuges may clog the centrifuge if the solid particles are too large or too numerous, resulting in high vibration shutdowns.
Although centrifuge separation experiments with sandy crude oil were conducted during the engineering phase of design selection, the effect of solid particles on centrifuge operation may not have been adequately considered.
High maintenance costs:
Maintenance costs are excessive due to the frequent failures that may occur during the operation of disk centrifuges. This may be related to factors such as the design of the centrifuge, the quality of manufacture, the level of operation and maintenance, and the complexity of the heavy oil emulsion.
Disc centrifuges do face some problems in the application of heavy oil emulsion dewatering, but by optimizing the design of water sealing of the emergency machine, improving the structure or operation of the centrifuge, improving the quality of feed, and strengthening the maintenance and repair, these problems can be effectively solved and the operating efficiency and dewatering effect of the centrifuge can be improved.