Water intake screen installation and method of straining water

A water intake screen installation comprising

• a channel for guiding a stream of water to flow in a predetermined direction,
• a water intake for receiving a quantity of water diverging from the channel stream,
• a traveling water screen unit positioned between the water intake and the stream of water flowing in the channel for straining the diverging water,
• said screen unit having an endless belt strainer in the form of a vertical loop with an upwardly extending screening surface that also extends laterally in a direction parallel to the predetermined direction of stream flow,
• said screen unit having a drive for revolving the endless belt strainer to elevate a portion of the screening surface relative to the channel, and
• means for directing a backwash current through the screening surface towards the stream of water flowing in the channel at an elevation above the diverging water and below the stream surface, whereby material retained on the screening surface can be dislodged by the backwash current and forced backwardly from the screening surface into the stream of water flowing in the channel to be carried away therewith,
• said backwash current directing means having multiple rows of jet nozzles at fixed locations, said rows being spaced vertically to cover the extreme variations of water level within the channel, and a water level sensor for actuating the row of jet nozzles that is located both below and nearest to the surface of the stream.

A water intake screen installation comprising

• a channel for guiding a stream of water to flow in a predetermined direction,
• a water intake for receiving a quantity of water diverging from the channel stream,
• a traveling water screen unit positioned between the water intake and the stream of water flowing in the channel for straining the divering water,
• said screen unit having an endless belt strainer in the form of a vertical loop with an upwardly extending screening surface that also extends laterally in a direction parallel to the predetermined direction of stream flow,
• said screen unit having a drive for revolving the endless belt strainer to elevate a portion of the screening surface relative to the channel, and
• means for directing a backwash current through the screening surface towards the stream of water flowing in the channel at an elevation above the diverging water and below the stream surface, whereby material retained on the screening surface can be dislodged by the backwash current and forced backwardly from the screening surface into the stream of water flowing in the channel to be carried away therewith,
• said backwash current directing means having a plurality of jet nozzles in a first row, first floating carriage supporting the first row of jet nozzles, a plurality of jet nozzles in a second row, a second floating carriage superimposes above the first floating carriage, said second floating carriage supporting the second row of jet nozzles, each floating carriage being movable through a predetermined vertical range, and fluid control means responsive to a water level sensor for actuating the row of jet nozzles that is located both below and nearest to the surface of the stream.

A water intake screen installation comprising a channel for guiding a stream of water to flow in a predetermined direction, a traveling water screen unit having an endless belt strainer in the form of a vertical loop with an ascending run portion and a descending run portion, said ascending and descending run portions extend from near the bottom of the channel to a location above the surface of the stream, said screen unit having a rotatable drive for revolving the endless belt strainer to elevate the ascending run portion and to lower the descending run portion, both said ascending run portion and said descending run portion being contiguous with the stream of water flowing in the channel, both run portions extending laterally parallel to the predetermined direction of stream flow, a water intake located to receive dual quantities of water diverging from the channel stream, one quantity passing through the ascending run portion and the other quantity passing through the descending run portion, and means for directing a backwash current through the ascending run portion of the endless belt strainer in a direction towards the stream of water flowing in the channel at an elevation below the stream surface, whereby material retained on the ascending run portion of the endless belt strainer can be dislodged by the backwash current and forced backwardly from the ascending run portion into the stream of water flowing in the channel to be carried away therewith.