Dense Phase Conveying

The other technique is known as dilute phase conveying. The primary distinctions between the two methods are pressure, the characteristics of the solids, and the rate of conveying speed. Transporting abrasive, brittle, or heavy materials like sand, soil, minerals, food, paper scraps, and boulders is specifically covered by dense phase conveying.

Principle of Operation

A pressure vessel is loaded from a silo, big-bag unloader, or process machinery, such as a mixer. The operation cycle entails loading the receiving hopper with material, applying pressure, and conveying the material as a plug or layer. With the "dense flow" PHF conveying system working at moderate gas velocities of 15–25 m/s, the solids can be transported as a continuous layer.

With the "pulse flow" PTA conveying system running at low gas velocities of 4–12 m/s, the solids can be transported as a pulsed plug. Finally, the solids can be carried as a pulsed plug using the "pulse line" PTA PL conveying system running at low gas velocities of 4–12 m/s with the addition of external air injectors installed along the pipeline for longer conveying distances and with maximum process safety.

Dense Phase Conveyor Design

There are various designs for dense phase conveyors, which are enclosed tubular conveyors powered by air pressure and commonly loaded by gravity or vacuum while discharging goods from the bottom. Due to the materials conveyed being so densely concentrated, they will naturally deposit at the bottom, which is why the bottom-discharge design, in particular, lends itself to dense phase conveying so effectively. However, vacuum-loaded dense-phase conveyors pull products through utilizing a vacuum.

Moving-bed flow and plug flow are the two different types of flow used in dense phase conveying. Plug flow happens when the material is transported in units known as plugs or slugs that are separated by air spaces rather than one fluid body, as opposed to moving-bed flow, which occurs when the material is transported down the bottom of the conveyor pipeline.

System Design Elements

The physical qualities of the object being handled are the first of several system design factors to be considered. Factors considered include bulk density, abrasiveness, friability, particle size/distribution/shape, moisture content, temperature, and static charge. A pneumatic conveying system's rate, length, and pipeline routing arrangement will impact the overall system design. A dense phase system will typically have a smaller line diameter than a dilute phase system of a similar size. The smaller pipeline will require less installation area and money. This advantage is particularly notable when the line routing is lengthy and has numerous bends.

Air Injection Within the Conveying System

Another consideration is whether the conveying system needs to include more conveying line air injectors. Periodic air injection along the conveying line will improve the efficiency of some systems. In the fluidization examples mentioned above, strategically adding air pulses ensures that bulk materials move properly and with the least velocity throughout the pneumatic conveying system. Additionally, air injection can lessen fine particle bridging in the transporter's cone.

The powder can bridge above the transporter cone outlet and stop pouring into the line without transporter cone aeration. The powder in the transporter cone will get fluidized by strategically placed injectors, maintaining a steady flow into the line. A system that runs smoothly and doesn't plug depends on the air injection's position and pressure, whether in the transporter or along the conveying line.

Additionally, strategic air injection will decrease the system's overall gas consumption for greater efficiency. The reliability of the system is also considerably improved. The placements of the air injectors must be chosen to optimize material flow and make accurate estimations of the motive gas volume and conveying pressure.

Advantages of Dense Phase Conveying

Let's discuss the benefits of dense phase conveying. A low-velocity motive gas moves bulk materials in dense phase conveying, which can move both positive and negative pressure differentials. Low velocity produces a gentle transfer with less wear and impact on the materials. For most abrasive, brittle, friable, or mixed-batch materials, dense phase conveying is excellent. There is less product waste due to decreased product breakage. Additionally, material segregation is minimized, lowering the possibility of problems with subsequent processes.

Applications of Dense Phase Conveying

Dense-phase conveyors move materials with a low air-to-material ratio and a moderately low velocity. Frequently, dense-phase conveyors generate high-pressure levels with the use of an air compressor to move goods through the system at a typical rate of 275 feet per minute. Dilute phase conveyors are frequently used in the pharmaceutical, chemical, food processing, foundry, mining, plastics, and cement sectors.

In addition, dense phase conveying is frequently utilized in bulk material handling applications because it is perfect for transporting large amounts of materials. However, dilute phase conveying may also be used if the transported materials are light and non-abrasive.

Choosing the Correct Dense Phase Conveying Company

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