A New Design for a Debris Catcher on the Hydroelectric Pipeline Intake

With the recent reconfiguration of the pipeline, called a “penstock,” for the hydroelectric turbine I began to give some thought to dealing with the problem of floating debris, and ever present problem in an intake system.  Since this reconfiguration the intake was protected only by a piece of 1/4″ hardware cloth, which clogged every few days with the autumn leaf fall, and the large trash grill I built to shroud the area.

The previous configuration allowed me to utilize a capturing basin (basically just a polypropylene tub) with a top protected by a Coanda screen I made myself.  The water was collected in the tub and the debris washed over the Coanda screen.  It worked just fine, and resulted in the need for clean-off only once or twice a year.

The new location of the capturing point being simply the end of the pipeline submerged into the stream was not amenable to a capturing tub with a Coanda.  So, an entirely new and different approach was needed.  After some noodling I settled on a device I made from two PVC fittings and some pieces of PVC pipe I had already ripped into slats for some reason long since forgotten.

By affixing the slats to the outside of the joint fitting and the PVC pipe cap I derived an apparatus that functions essentially as a piece of perforated pipe.  But it has two fairly important differences from something like a piece of drain pipe.  First the openings are vary narrow slits, about 1/16″ wide, preventing anything from entering into the system that might clog the water jets down at the turbine.  Second, the orientation of the slits long-wise, in other words parallel to the flow of the water, should provide a self-flushing effect for any debris sucked to the surface of the cylinder.

I’ll know soon enough whether the new arrangement works long-term.  On Thursday we installed it, and the system is humming along just fine.  I will check it again tomorrow to see the situation.  The heaviest leaf-fall will be in less than a week, and although the large grill over the area should handle most of the debris it will not catch it all.

Stay tuned.