22 May 2013:
Side Hill Screens
As we have stated previously, we are going to be taking the ideas developed in this column over the last couple of years and developing them into design practices. This is how it works. We will provide the basic narrative here for one design practice each week. We will keep it open for comments for one month. After that, we will finish it in formal form and offer it for sale at a modest price. Here is where you come in. If you make a substantive contribution to a standard, the organization for which you work will be granted a pro bono license to use that standard with its current issue number for as long as you like. We have had good response so far! Contribute, please.
Side Hill Screens (LGM 2013.020.01
The side hill screen is a low-cost, low-maintenance screening technology. The SHS element is a curved, slotted, wedge-wire screen with slots ranging from 0.010" to 0.125" oriented perpendicular to the direction of flow. In the paper industry, side hill screens may be used as a thickener in the recycling process or as a rejects separator in cleaning.
Wedge-wire screens are formed by laying stainless steel wires, having trapezoidal shaped cross-sections, parallel to one another with a small gap between them. The openings therefore are long slots. With a wedge-wire screen the shape of the target particles will greatly influence the efficiency of removal. Three dimensional hard particles will be removed at a much greater efficiency than flat scaly particles that could orient themselves to slip through the slots.
Instead of stainless steel, side hill screens can be manufactured from a lightweight frame and a surface something like a forming wire. This will not only reduce the weight of the screen, but may lead to lower costs in some cases, depending on the material used.
To construct side hill screens using lightweight material.
This design would have to be less expensive than fancy lamella like surfaces.
Additionally, we can see the possibility that the desire for a different consistency would only require a change of the wire.
As always, your comments will be appreciated.
Brian Brogdon, Ph.D.
Send us your comments by emailing Brian Brogdon
or Jim Thompson!