Debris Filter

Why Debris Filter?

Fouling phenomena are common and diverse, ranging from fouling of ship hulls, natural surfaces in the marine environment (marine fouling), fouling of heat-transfer components through ingredients contained in the cooling water or gases.

The following are examples of components that may be subject to fouling and the corresponding effects of fouling:
[list type=note]

  • Heat exchanger surfaces – reduces thermal efficiency, decreases heat flux, increases temperature on the hot side, decreases temperature on the cold side, induces under-deposit corrosion, increases use of cooling water;
  • Piping, flow channels – reduces flow, increases pressure drop, increases upstream pressure, increases energy expenditure, may cause flow oscillations, slugging in two-phase flow, cavitation; may increase flow velocity elsewhere, may induce vibrations, may cause flow blockage;
  • Ship hulls – creates additional drag, increases fuel usage, reduces maximum speed;
  • Turbines – reduces efficiency, increases probability of failure;
  • Solar panels – decreases the electrical power generated;
  • Reverse osmosis membranes – increases pressure drop, increases energy expenditure, reduces flux, membrane failure (in severe cases);
  • Electrical heating elements – increases temperature of the element, increases corrosion, reduces lifespan;
  • Nuclear fuel in pressurized water reactors – axial offset anomaly[3], may need to de-rate the power plant;
  • Injection/spray nozzles (e.g., a nozzle spraying a fuel into a furnace) – incorrect amount injected, malformed jet, component inefficiency, component failure;
  • Venturi tubes, orifice plates – inaccurate or incorrect measurement of flow rate;
  • Pitot tubes in airplanes – inaccurate or incorrect indication of airplane speed;
  • Spark plug electrodes in cars – engine misfiring;
  • Production zone of petroleum reservoirs and oil wells – decreased petroleum production with time; plugging; in some cases complete stoppage of flow in a matter of day.

[/list]

Debris Filter

Despite all of the pre-screening technology employed at raw cooling water intake sites, it is clear that additional filtration is often required to avoid macro fouling of the units served. The solution to this problem is provided by the Automatic Debris Filter.

It is designed to effectively prevent macro fouling by fibrous, course and marine life debris (larger than the selected filter perforation size), by capturing and ejecting all debris in an optimal manner. The optimal cleaning capability is achieved through the incorporation of dedicated suction ports for the two basic classes of water borne debris (course and fibrous).

The basic structure of the debris filter is illustrated above. The filter membrane (1) is cone shaped with debris laden water entering on the concave side. The size of the filter element perforations are supplied according to debris conditions. A debris evacuation conduit is located on the inlet side (2). The conduit is set into bearings at its extremities and is rotated by a motorized drive mechanism(6)

The conduit features one or more slotted suction heads (3) for removing fibrous material captured by the filter and impinged on the filter element surface. A broader suction head is located (4) at the downstream end of the conduit to extract larger coarse and marine type particulates. The slotted heads have flexible sealing lips (5) which concentrate suction on the filter surface directly at the point of treatment. Due to the rotation of the heads, the screen angle and flow direction, larger coarse debris is conveyed to the suction head (4) at the apex of the filter for evacuation. The debris evacuation pipe (7)is opened or closed by the built in valve (8). A differential pressure monitor (9)continuously assesses the amount of debris collected on the filter element and controls the operation of the debris evacuation apparatus.

When debris build up creates the critical predetermined differential pressure across the filter, the evacuation sequence is initiated. The valve on the debris evacuation pipe automatically opens and the debris evacuation aparatus is actuated. The differential pressure at the heads creates the vacuum by which all debris is evacuated. The filter continues to clean itself until the monitor indicates a clean condition exists. The rotation of the conduit then is automatically stopped and the valve on the evacuation pipe closed.

The debris filter is controlled by a PLC based local control panel. The front of the control panel has a mimic diagram and all the controls and instrumentation required to operate the system.

[flexislideshow]

Debris Filter in standby mode. Entrained particulates are being strained out of the flow and accumulate on the inside of the conical filter element. As the accumulation continues, the differential pressure across the element climbs. In this mode the unit is not actuated, nor is debris or flow being discharged. When the differential pressure reaches a preset limit, the self-cleaning mode is initiated. The debris discharge valve opens causing debris impinged on the filter directly over the debris evacuation ports to be pulled free and discharged by means of the differential pressure between the downstream side of the filter and the pressure at the point of debris discharge.

Technical Data:

TYPE
VOLUME FLOW 1800 – 50000 m3/hr
CONNECTING DIAMETERS DN 500 – DN 2800
FILTER FINENESS
FILTER ELEMENT PERFORATED SS SHEET
MOC STEEL, RUBBERLINED
TEMPERATURE MAX 80OC
DEBRIS DISCHARGE CAPACITY                 . 1.6 ltr/m3                                               .

 

[list type=check]
  • High performance with excellent performance ratios
  • Low backwash flow rates and low pressure loss for minimized operational costs
  • Extremely simple maintenance: all drives, bearings and sealings easy and accessible from outside
  • Installation in any position, that means horizontally, vertically, and under any angle to fit the space conditions of the pipes.
  • Extremely short overall length creates installation possibilities under restricted space conditions, especially for retrofits.
[/list]