Discharge valves blow tank

Reliable valves for blow tank filling, venting and discharge. 

It should be realized also that either option shown in Fig. 9 or 10 will produce a non-symmetrical flow pattern inside the blow tank (i.e., due to preferential feeding at the blow tank outlet) and hence, promote the possibility of arching, rat holing and/or formation of dead regions. For these reasons, the combined fluidizing-discharge-cone and cone-dosing valve system shown in Fig. 8 is preferred. 

The blow tank is automatically taken through repeated cycles of filling, pressurizing and discharging. Since one third of the cycle time is used for filling the blow tank, a system required to give a mean delivery rate of 20 t/h must be able to deliver a peak rate of over 30 t/h. Dense phase transport is thus a batch operation because of the high pressures involved, whereas dilute phase transport can be continuous because of the relatively low pressures and the use of rotary valves. The dense phase system can be made to operate in semi-continuous mode by the use of two blow tanks in parallel. 

Although positive pressure conveying systems discharging to a reception point at atmospheric pressure are probably the most common of all pneumatic conveying systems, the feeding of a material into a pipeline in which there is air at a positive pressure does present a number of problems. A wide range of material feeding devices, however, are available that can be used with this type of system, from venturis and rotary valves to screws and blow tanks. 

Road and rail vehicles Road vehicles are widely used for the transport of a multitude of bulk particulate materials, such as cement. Hour, sugar and polyethylene. Road vehicles often have their own positive displacement blower mounted behind the cab and so can off-load their materials independently of delivery depot facilities. The material containing element on the truck can generally be tipped to facilitate discharge, which can be via a rotary valve, or the container might double as a blow tank that can be pressurised. 

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