Pusher furnaces

In pusher furnaces, the product (work load) is pushed through the furnace in steps by a hydrauhc or electromechanical mechanism that pushes each load into the furnace, thus pushing all work in the furnace ahead one work space. The walking-beam furnace lifts the work load on a walking beam, advances the load a step, and returns the work to the hearth. The walking beam then returns to its original position (under the hearth) in preparation for the next step. 

Purple permanganate ion, 15 597 Purple pigments, 7 349-350 for inks, 14 318 Pusher centrifuges, 11 392 Pusher furnaces, 12 289-290 Push-pull coupler device, 13 422 Push-pull rods/barrels, 24 59 Putrescine, 2 79... 

In contrast to the pusher furnace, where a static powder layer passes the furnace, a dynamic powder flow exists in the rotary kiln. Furnace rotation and the incline continuously move the powder through the hot zone. Feed rate, rotational speed, incline, and lifters inside the tube determine the depths of the dynamic powder layer. High oxide feed, longer retention time (low rotation rate and low inclination), and higher temperature result in coarser tungsten grains. 

Advantages of the rotary furnace compared to a pusher are less specific energy consumption (valid only for median grain sizes), while automation is less complicated and consequently maintenance is cheaper. Finally, the product is more homogeneous and less contaminated, but the particle morphology may differ significantly from powders produced in pusher furnaces. 

For (1) and/or (2), a small manual pusher furnace can be applied in which parts on a tray are moved through a furnace, one tray at a time (Fig. 9.4). If it features gas tight... 

Fig. 9.4 Sketch of a longitudinal section-box or manual pusher furnace [B.25],...

Fig. 9.22 Photograph of a high temperature pusher furnace (courtesy Gasbarre, Sinterite Furnace Div., St. Marys, PA, USA).

Fig. 6.7-45 Diagram of the manufacturing process of (hollow) building blocks made from lime and sand. 1, lime ball mill 2, elevator 3, wind sifter 4, 9, 11, silos 5, metering bucket 6, screw conveyor 7, sand feed 8, screen 10, batch mixing and hydration drum 12, proportioning 13, elevator 14, stone press 15, block cart 16, transfer platform 17, post-treatment (hardening) chambers 18, steam production Fig. 6.7-46 Sketch of a manual pusher furnace [B.28, B.97j...

Disadvantages of walking beams relative to pushers are that walking beams have nearly twice as much skid-mark area and heat loss to water as pusher furnaces because of the walkers of the walking beams. However, these can be eliminated by a short soak zone at the discharge end of the furnace. (See reference 3.)... 

Fig. 2.19 CARBOFLEX - continuous carbon control and optimising system on a pusher furnace.

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