Construction of separator vessels
The Horizontal Repack Coalescers series HDPC consist of horizontal oriented pressure vessels provided with mass packed coalescing media.
The vessels are provided with a full opening cover to allow inspection and replacement of the repack coalescer. The cover is provided with a curved head to provide additional volume and to assist equal laminar flow through the repack coalescer. For ease of maintenance the inlet is located on the main vessel body to allow access to the vessel without the removal of piping. Behind the inlet nozzle the repack coalescer is mounted. The repack coalescer is supported in the flow direction by a removable grid. The grid can be removed to inspect or clean the space behind the grid. Behind the grid a settling space with a water collecting sump is located. The sump can be provided with connections for level indication and/or level control instruments. The outlet is usually located on top of the horizontal vessel at the far end and is, depending on the size and application, provided with a baffle plate to assist a favorable flow pattern through the vessel.
The coalescer internals consist of mass packed coalescing media and are available in a choice of materials, including but not limited to excelsior, fibreglass, steel and stainless steel.
Repack coalescers will remove free water with an efficiency of 98% to 99% with a minimum of approx. 100 ppm water outlet concentration, depending on the material types used, and will remove a considerable amount of mechanically emulsified water. The massive amount of coalescing material makes the repack coalescers less vulnerable to surface active materials which may disarm coalescers with less coalescing materials.
The repack coalescer will also function as an effective depth type of filter. The large amount of coalescing material allows for a less dense packing. Therefor the solids retention size from repack coalescers is larger than the solids retention size from coalescer cartridges. Typical solids retention for repack coalescers is depending on the actual coalescing material used, but ranges from 30 to 60 micron. Combined with the high solids holding capacity provided by the depth of the media the Repack Coalescers are especially suitable for applications with considerable solids loads.
Principle of operationWhen the liquid enters the vessel the flow velocity is reduced due to the larger diameter of the vessel. This reduction in the flow velocity allows large droplets of water and large solids to settle. Due to the shape of the inlet part of the vessel the flow is equally divided over the diameter of the vessel. The liquid enters into the mass packed coalescing media and as the main phase is progressing droplets of water are removed by impingement on the media while solids are removed by depth filtration. The separated water will move along the fibres of the media and will coalesce with other droplets to form bigger droplets. At the end of the repack coalescer the droplets are allowed to settle in a settling zone. Here the droplets are settled by gravity and the water is allowed to gather in a water collecting sump. The main phase will leave the separator from the far end top.
Contruction of repack coalescers
General: The outside diameter of each repack coalescer is controlled to assure that liquids do not by-pass at the vessel wall. To prevent channeling the repacks are machine packed as full-diameter packs. The packs are contained with wheel type grids and metal screens at each end and are securely tied with heavy wire to prevent deformation in operation. Standard grids wires and screens are carbon steel, galvanised for protection against corrosion. Stainless steel or monel can be made available upon request.
Basic cylindrical repack coalescerThe basic cylindrical repack consists of one packed lot of material. Due to the size and weight this type of Repack Coalescers is only available for smaller sizes. The cylindrical repack coalescer can be produced from excelsior, glassfibres, carbon steel or stainless steel and is interchangeable with repack coalescers from other types. Other materials can be made available upon request.
Wafer repack coalescerThe wafer repack coalescer consists of a number of sections of packed coalescing material which can be handled and replaced separately. This allows for easier handling of the larger sizes of repack coalescers. Additionally it allows for the replacement of the first (or the first two) section(s) only if the surface area of the Repack coalescer is blinded off by solids.
The wafer repack coalescers are interchangeable with the cylindrical dehydrator packs without adaptation of the pressure vessels and they are available in the same materials.
Combination repack coalescerCombination repack coalescers are like wafer repack coalescers consisting of sections of packed coalescing material. They are especially designed for applications were large percentages of water (typically over 3% of water) can be expected. Alternate layers of dense coalescing materials and course coalescing materials allow for the quick removal of the formed droplets.
The sections of the combination repack coalescers can be changed independently.