Sand Removal Equipment from seawater intake

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Hi All

I am reviewing a P & ID, which a very old scan document.  The P & ID is for a certain 'sand removal equipment' placed in between traveling band screen and bar screen of a power plant intake system.  I have never come across such an equipment.

Can anyone help me understand what is a 'sand removal equipment'?

Thanks

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11 Answers

  1. Mr. Mansuri,

    Seawater intake takes non-stop water to the Pump Station, and in some days with turbulence or storms, the water has more sand particles in suspension that arrives to the pump station. From there, Pump takes water and when some sand goes into the pump, it could be damage. That's why pump stations should have some way to remove this sand out. You can find locks or floodgates to allow the access for manual removal or some devices (cyclotrons, conveyors,...) to remove this sand out as well as in the construction (Civil works) you can find some channels with another botón edge or level in order to avoid sand dispersion and concentrate the sand in some places to control its levels as well as maintenance remove it (By manual or by mechanical means.

    You can find it in quite all Pump Stations, and when it was not done, they claim to the engineering... Cyclones are a good solution as well as conveyor and bar screen.

    Regards,

     

  2. Mr. Mansuri,

    You should check the Offshore Technology Conference.  I have seen several vendors that had sand separators for offshore oil and gas work. 

    My suggestion is to not get sand inside the intake prior to cooling.  The hydrocyclone will work, but there is an energy penalty for using it. If there is space, a settling basin should work.

    Your statement about cyclones not employed in seawater, I believe, is incorrect.

  3. Is it a Circular Chamber?  Please share the PID. Typically any waste water treatment plant or a Water treatment plant scheme consists of Inlet Works like Pumping Station /Screening / Sand or grit removal following by primary sedimentation / clarification.  

  4. Sand can damage or deteriorate equipment. There are several way to remove sand from water or wastewater entering a process. Essentially all rely on the fact that sand is much denser than other materials that may be contained in the influent stream. Slowing flow velocity to about less than 2 ft/s (0.6 m/s) will cause sand to settle. This can be done in a dedicated container called a "grit chamber". There are also hydrodynamic separators that use centrifugal force to achieve the same results with less moving parts. A good textbook on the fundamentals of wastewater treatment will contain more detailed information.

  6. I’m agree with Jhon, hydro cyclones are most common used in pump stations sandbox areas. I saw special structures with mixed mixer pumps to clean all the pump station area pulled by electric winches.

  7. thank you for your responses, but cyclones are not employed in seawater applications.  This sand removal equipment may not be a cyclone.  The equipment is placed in an intake chamber (civil construction), each chamber has bar screen, trash rack, (the equipment in question) and travelling band screen in series.

    1 Comment

    1. Can you share the pic? Could be a Vortex Type Grit removal Chambers,. Typically the git is collected in the lower grit chamber, which shall be pumped to a Hydro Cyclone to separate waster / organics / sand. 90 to 95% of the Water and Organics  are separated from the top of the cyclone, the remaining 5 to 10% of sand  slurry collected in the Screw Classifier, for final dewatering.

  8. Sand removal can be done by the hydro cyclones if they are designed properly . it works on the centrifugal force created by the shape and  intake .

     

    No moving parts so it a simple and efficient system .