Slot venturi

Slot venturi A device used to adjust the pressure drop in a scrubber. 

In general, once the curtain of filaments has been produced, it is necessary to attenuate the filaments in order to provide strength and resistance to deformation. The most commonly practiced approach is to utilize a single slot, which is at least the width of the curtain, at a point below the spinning plate and above the laydown screen. There are two practical approaches taken. The first utilizes the injection of low pressure air at a point above the slot so that the fibers attain sufficient acceleration in the slot to provide adequate draw (22) (Fig. 7). The second utilizes a low pressure vacuum below a venturi to provide the pressure differential requited for sufficient acceleration and resulting attenuation (30). 

One of the limitations of the curtain/slot draw process is that the amount of fiber attenuation is constrained due to the short distance generally allowed between the spinnerette and the venturi slot and the use of relatively low pressure air for drawing so as not to induce high turbulence in the area of the laydown. In practical terms this has made the process difficult to adapt for the production of polyester fabrics which inherently require much higher fiber acceleration to attain the desired polyester fiber properties. 

Low dry tray pressure drop. On sieve and fixed valve trays, this means high (>11 percent) fractional hole area. On moving valve trays, this means venturi valves (smooth orifices) or long-legged valves (>15 percent slot area). On all trays, the channeling tendency and severity escalate rapidly as the dry pressure drop diminishes (e.g., as fractional hole area increases). 

The pressure losses of electric separators in comparison with the other types are very low, ranging between 60 and 250 Pa. A good separation efficiency with saving optimum operation conditions may be achieved in mechanical dry separators as well as wet separators at pressure losses of 600 to 1200 Pa (except for Venturi and slot separators). Considerable pressure losses occur in the filtration layer. Their values depend on the layer porosity , diameter of filtration material fibres, layer thickness, gas dynamic viscosity and the velocity of the streaming gas. 

LTC, Switzerland Venturi slot tunnel Fluidized bed Oven... 

University of Venturi slot tunnel Electrostatic powder Electrostatic charges. 

Virginia Polytechnic Venturi slot tunnel Powder deposited Oven eliminates... 

Figure 3.10 Schematic cross section of an ion source and drift tube from the laboratory of one of the authors. Here the drift tube is constructed from a single block of Teflon and the metal electrodes are located in slots on the outside of the drift tube. A Venturi inlet was employed to introduce the analyte gas into the drift tube. HC refers to the hollow cathode discharge region...

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