My prior U.S. Pat. No. 2,920,923 of Jan. 12, 1960 teaches the desirability of including a quantity of a "pseudo-fluid" between a slug of water and a slug of slurry in a pipeline used for the transportation of the slurry. The pseudo fluid is also known as a "cap." The utility of the pseudo fluid or cap is to exert a suspending influence on the relatively coarse particles of the solids in the slurry which is substantially greater than the suspending force exerted by the liquid alone. Preparation of the pseudo fluid or cap is carried on as a separate operation and one must be present between each slug of water and slurry. In accordance with this invention, the pseudo fluid or cap is created from the slurry itself and in a very simple manner, thus facilitating the pumping of the slurry and decreasing the overall cost of operation.
Method and apparatus for transporting a slurry along a pipeline having a number of downstream delivery points along its length and a plant at each delivery point for burning or otherwise using a part of the solids, such as coal, obtained from the slurry. In the practice of the method, the pipeline is filled with a carrier fluid, such as water, and batches of slurry are introduced between batches of the carrier fluid for movement along the pipeline. Each batch of slurry is separated from the batches of carrier fluid by a cap and a tail, the cap and tail being formed from a liquid suspension of fine solids. At each downstream delivery point, each batch of slurry and its cap and tail are directed out of the pipeline into a holding tank. A portion of the contents of the holding tank is removed from the holding tank and dewatered to produce a large mesh solids cake and a centrate defined as a liquid suspension of fines. The remainder of the contents of the holding tank and a cap and tail formed from the centrate is then directed into the pipeline downstream of the delivery point between the batches of carrier fluid for transit to the next delivery point along the pipeline. The foregoing steps are repeated at each successive downstream delivery point along the pipeline. At each delivery point, the cake formed by dewatering is burned or otherwise used at a plant at the delivery point. At the last delivery point, the remaining slurry is dewatered and used. the invention eliminates the need for grinding solids at each downstream delivery point to form the caps and tails material needed to isolate the batches of slurry from the carrier fluid sent on to the next delivery point.
