• Blockage reduction to increase the efficiency of slurry application.

      Ryan, D.; Brett, P. (Teagasc, 1999-12-01)
      Discussions with farmers using band and injection slurry spreaders suggested that the rate of breakdown due to blockages, in these machines, was approximately one per day. This report shows how the use of an intake filter and a modified distributor on a band spreader can reduce this problem. A set of obstacles was assembled on the basis of information from farmers and from literature. Ten classes of obstacles were selected, at random, and between size limits. Two prototype filters, a commercial filter and an open pipe were tested while drawing slurry from an open tank to a tanker. During each test, obstacles were thrown into the slurry stream. Obstacles retained by the filter were counted afterwards. A second filter trial was organised to test the tendency of filters to clog. Obstacle tests with 3 prototype distributors and a control were conducted in a similar manner to the first filter trial but, in this case, preliminary tests were conducted in water and final tests in slurry. The initial tests identified the best prototype. This was then compared to the control distributor using slurry. The open pipe allowed 80% of obstacles to pass while the filters allowed only 4 – 19% through. The new filters offered no improvement over the commercial unit. Filters required 16 hours agitation but the open pipe required 4 hours or less. The best prototype had the same diameter as the control but had an obstacle trap attached at the side. In a test using obstacles and slurry, the control was obstructed by 56% of the obstacles while the prototype allowed only 21% to cause a blockage. Flow through the prototype was initially too large. Slowing down the rotor in the distributor and restricting the outlet from the obstacle trap with a single long pipe, connected to two nozzles, controlled the flow. The results of the filter and distributor trials were combined. Of the seventy obstacles dropped above the filter, six passed through. Four of these caused blockages in the control distributor, but only one became stuck in the prototype. The blockage rate in the distributor and nozzles was significantly reduced compared to the original unit.