jul 15, 2013

Olds Elevator: Impressive heatexchanger for hot foundry sand



Olds elevator used as a heat exchanger for foundry sand shows impressive performance.

Hudson, New Hampshire (March 4, 2010) - Olds Elevator LLC of Hudson, NH and Palmer Mfg. and Supply Co. of Springfield OH collaborated on a series of trials using an Olds elevator as a heat exchanger for hot foundry sand by running tap water through the hollow shaft of the Olds elevator's static screw.  During normal elevation of hot sand, heat is extracted through the screw by running a stream of low-flow (2 gpm) tap water through the screw shaft.  The elevator/heat exchanger was tested under a range of conditions of sand flow, sand temperature and water flow rates. Refer to photo of test equipment configuration.  A description of the equipment setup is: Left to right: Olds elevator: 12 foot tall, 5.875 inch ID rotating casing, 5.25" OD static screw with 1.25" hollow shaft. Screw flighting continuously welded to shaft top and bottom. Water line feeds tap water into bottom of screw shaft.  Flow is regulated by a valve with in-line flow meter...  Elevator controlled with VFD to allow regulation of sand flow rate to a maximum of 5.58 tons/hour Sand Heater:  Electrically heated elements in fluidized bed by compressed air supply.  Sand supplied from Olds elevator discharge. Heated sand fed directly to Olds elevator feed hopper. Sand Heater Controls: Air flow and temperature controls Examples of the effectiveness of the elevator/heat exchanger at different flow rates:

Sand Flow lb/min Water Flow GPM Water Temp In T°F Sand Temp In T°F Sand Temp Out T°F Water Temp Out T°F % Heat Reduction Sand
63 2 47 187.5 140.2 61 25.4
96 2 47 189.5 146.0 63 22.9

Additional testing is scheduled using hollow flighted screws, in addition to hollow shafted screws, which will triple the surface area of the chilled screw surface in contact with the moving sand.