a trial is organized to design an industrial dense phase pneumatic conveying line for a material that is sensitive to breakage. the industrial line must be able to convey 8 t/h the pipe layout is 50 m including 15 m vertical and has 5 bends. the design needs to know the following :
dilute phase conveying the basic system. magnum systems’ knowledge of products/materials and broad range of dilute phase systems and components put the right equipment in place whether your building one from scratch reconfiguring or repairing. our engineers know the components and their properties by heart.
figure 1: dilute-phase conveying system pneumatic conveying is achieved by creating a pressure differential along a pipeline and using the air that moves toward the area of lower pressure to move bulk material. this process can be performed with a vacuum inducer or by injecting compressed air into one end of a pipeline or along the pipeline.
however if stressed laterally they can be prone to misalignment. by comparison flanges are used in pipe systems and commonly used on higher pressure >15 psig dense phase systems. a number of companies now sell self-aligning flanges which help to minimize off- grade particles and conveying system wear.
although the 5000 pounds cycles only once per hour because the rate of transfer is higher during that 15 minutes it is actually moving at 20000 lb/hr thus requiring a more powerful vacuum source. dilute phase pneumatic conveying systems can transfer up to 25000 lb/hr via vacuum.
dense-phase vacuum has a limitation on conveying distance — 60 to 90 meters 200 to 300 feet — based on the energy that can be produced by a vacuum blower or pump. this method is also very well suited to fragile and/or sticky materials because the material is pulled through the convey line rather than pushed as in a pressure system.
there are various dense phase conveying methods available that gently convey a specific bulk material and therefore reduce the risk of material degradation and wear. in many cases a dense phase pneumatic conveying system offers a higher quality end product which offers greater value to the user at the final destination.
figure 4 : pressure dense phase typical process arrangement. vacuum - dense phase. a vacuum dense phase system is quite similar to a lean phase setup except that a vacuum pump allowing to reach pressure <-900 mbarg should be installed. the inlet of material is usually done through a sender hopper.
figure 2: dense-phase conveying system. pneumatic conveying systems for bulk materials many material-handling plants transfer large quantities of materials often over long distances. as a result the conveying system’s power consumption is of prime importance.
while a number of parameters will influence the performance of a pneumatic conveying system such as air flow rate solids flow rate pressure drop equivalent length of the pipeline solids concentration and others it is the gas velocity in the pipeline that is the key parameter for dense phase conveying.
dense phase vacuum conveying systems utilize high capacity vacuum pumps to convey the material from a feed hopper or silo to another destination. the system operates similarly to the dppc system. this system much like the dppc system generally operates on a batch basis.
- when using dilute phase pressure pneumatic conveying the material dilution rate in the air is very important and therfore requires a high throughput rate of air to convey the material. - the greatest advantage of dilute phase pressure pneumatic conveying is the ability to supply several reception points as from a supply point.
dense phase pneumatic conveying is a relatively low-speed system where the material is not suspended in the air stream. the low velocity of dense phase means less wear and tear on both the system and the materials being conveyed. the velocity is typically set between 400 ft./min. and 1000 ft./min. though there are several forms of dense conveying.
the calculations for the design of a dilute phase conveying sys-tem are based on determining the pressure drop that is gener-ated in the system due to the flow of gas and solids. zenz and othmer state that this pressure drop for both dilute and dense phase conveying is composed of six effective forces: 1.friction of the gas against the pipe wall.
pneumatic conveying design guide second edition david mills this provides an understanding of dilute and dense phase conveying modes solids loading ratio and the inﬂuence of pressure and convey- including vacuum systems following developments in this area with regard to blow tanks rotary valves
when issues of this type are present most plants will consider selecting a higher pressure dense phase pneumatic conveying system. dense phase systems from 15 to 50 psig. high pressure systems are known as dense phase pneumatic conveying systems. these systems utilize air pressure above 15 psig up to 50 psig at the entry and use positive pressure to push materials through the conveying line at relatively low velocities from 100 fpm to a maximum of 1000 fpm much like extruding.
dense phase pneumatic conveying is a relatively low-speed system where the material is not suspended in the air stream. the low velocity of dense phase means less wear and tear on both the system and the materials being conveyed. the velocity is typically set between 400 ft./min. and 1000 ft./min. though there are several forms of dense
pneumatic transport handbook types of pneumatic conveying conveying phases dilute phase transport dense phase transport air mover roots blower roots blowers performance curve after cooler airlock rotary valve product inlet / injector piping filters pick up velocity saltation velocity choking velocity conveying speed / velocity air volumetric
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