Hydrocyclones have been used for a number of years in offshore petroleum platforms for separating oil and other residue from water so that the water is clean and environmentally suitable for discharging into the sea and the oil may be directed to a suitable transport for shipping to a refinery. Such hydrocyclones are used for separating fluid mixtures having a wide range of oil/water proportions. Some hydrocyclones are designed to separate oil from water, others are designed to separate water from oil, and there are still others that are designed to separate mixtures of generally equal proportions. The latter hydrocyclones are sometimes referred to as pre-separation hydrocyclones since the outlet streams are often directed to dewatering and de-oiling hydrocyclones as is known. With the space limitations and weight carrying capacity of an offshore platform, weight and size of most equipment is carefully scrutinized. Accordingly, there has been a lot of developmental work on improving the efficiency of the hydrocyclone operation so that the oil outlet stream includes minimal water content and the water outlet stream includes minimal oil content. As the hydrocyclones have further developed in both complexity and capacity, the vessels in which they operate have become bigger to handle the equipment and additional liners used to separate the liquid constituents.
Referring to FIG. 1, there is shown a simplified prior art design of a hydrocyclone generally indicated by the number 10. The prior art design includes a vessel 20 having a liquid mixture inlet port 21 generally at one end and a water outlet port 22 generally at the other end. Within the vessel 20, there is a mounting plate 25 having a plurality of openings through each of which a liner 30 may be inserted and mounted. The plate 25 divides the vessel into an inlet chamber 26 and a water outlet chamber 27. As may be more clearly understood from FIG. 2, the plate 25 is comprised of two plate halves 25A and 25B which define a plenum for the receipt and collection of oily water. The oily water is discharged from the vessel through a conduit 25C which leads to a oil outlet port 23 at the side of the vessel 20. As can be more clearly seen in FIG. 2, the liner 30 comprises a number of elements that are assembled at the vessel 20. The liner 30 comprises an elongate tube 31 having a reducing inner diameter, an involute inlet head 32 connected to the larger diameter end of the elongate tube 31 for admitting the liquid mixture into the liner 30 and directing it into a swirling motion, and an overflow gallery 33 for collecting the overflow fluid exiting through the axial port in the involute inlet head and directing the overflow fluid though the passage indicated at 35 to the interconnected plenums in the plate 25. The elements 31, 32 and 33 are stacked and held together by bolts 37 which are attached to the plate 25 by screw threads. To assemble a number of liners 30 in a vessel requires significant manual labor holding each of the elements in position to insert a bolt down through the stack, threading and tightening the bolts. In the adverse conditions of an offshore platform, maintaining the vessel may be quite difficult and time consuming as well as a safety hazard for maintenance personnel.
Additionally, the combination of the bolts and the overflow gallery add significantly to the dimension of the liners. As noted above, platform space is critical and any waste of space will not be tolerated. The capacity of the hydrocyclone apparatus is determined by the size and number of the liners. With the space taken by the return line in the overflow gallery, and the space used by bolts prevents using any additional interior vessel space for adding to the capacity of the vessel 20.
Accordingly, it is an object of the present invention to provide a hydrocyclone apparatus which overcomes the drawbacks and disadvantages of the prior art as discussed above.
It is a more particular object of the present invention to provide a hydrocyclone apparatus which has greater fluid separation efficiency in the smallest possible package.
It is a further object of the present invention to provide a hydrocyclone apparatus which is less complex than prior art hydrocyclone devices and is more easily serviced by maintenance personnel.