Solids draining screw

Melt-draining screw See solids-draining screw. 

Another version of a CIS extruder is the solids draining screw (SDS) originally developed by Klein and Tadmor [21] of Scientific Process Research, Inc. In this design, unmolten polymer drains into the inner screw see Fig. 10.60. 

Melt-Draining Screw see Solids-Draining Screw. 

Material is transported upstream in the inner screw and plasticated. At the end of the inner screw, the polymer, which is now molten, is pumped back into the channel of the main screw. A modified version of the SDS screw for use in a molding machine was patented on September 22, 1981 [22]. Another modification of the SDS screw involves using a barrier type main screw to improve the solids draining process. This barrier SDS screw was patented on June 14, 1983 [23]. The SDS screw is claimed to give higher output and lower energy consumption. However, from a functional analysis it is difficult to see why recirculation of a fraction of the polymer flow would increase output or reduce power consumption. 

A somewhat similar but simpler design uses a horizontal screw section for leaching and a secona screw in an inclined sec tion for washing, draining, and discharging the extrac ted solids. 

The filtered sohds from the filter press (filter press-cake) are dropped into a hopper equipped with a variable-speed screw that meters the filter cake into the fresh material. The feed to the screw-press, therefore, is a blend of fresh material, drained solids, and filter press-cake. The ratios of the blend ingredients should be kept constant. This will maintain the screw-press in steady-state operation. If all of the filter cake is recycled at once, for example, followed by several hours of no filter cake, the screw-press performance will change as feed composition changes. Figure 16 shows a typical screw-press operation with all of the above equipment in place. 

After the cooking process is completed, the cooked material is drained and pressed to remove the fat using either a hydraulic or screw-press. The solid protein (cracklings) is then normally ground with a hammer mill. After the hammer mill. 

Some of the centrifuged solids obtained from the equilibrium adsorption studies were immediately subjected to consecutive desorption analyses. The liquid centrifugate was carefully drained from the test tubes and replaced with 25 ml of organic-free water. The tubes were then sealed with the teflon-lined screw tops and agitated for 24 hours. The tubes were then withdrawn, centrifugated, and the centrifugate analyzed as before. This procedure was performed several more times. Representative results from these... 

Skin maceration in a membrane tank (Elite-Pera) is a process situated between maceration in a pneumatic press and tank maceration. At the end of maceration, the juice is collected first by natural draining and then by inflating the tank membrane, incrementally increasing pressure (0.1-0.25-0.4 bar). Ninety per cent of the juice can be collected by this method. The drained skins are transferred by gravity into the press with the help of a screw conveyer. The juices obtained by this method do not contain many suspended solids (200-300 NTU) and are particularly well protected from oxidation. 

The short transition screw had a compressing ratio of 4 with 9 turns of feed 1 turn of compression and 14 turns of metering. The Barrier and XLK screws had feed sections of approximately 20.3 mm (0.8 inches) depth and 8 L/D in length. The Barrier screw had approximately 10 turns of transition and 6 turns of combined homogenization and metering. The XLK screw had a comparable feed section as the Barrier screw and an extended transition section of approximately 14 L/D with a constant depth section of approximately 2 L/D with a solids dam to drain the melt into the inner screw for discharge from the extruder. 

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