Now we know the differences between a dense phase and dilute phase pneumatic conveying system or bulk material handling system, but how do you select the correct pneumatic conveying system for your application?
Major Factors to Consider
The first thing to address when selecting a dilute- or dense-phase pneumatic conveying system is your material’s characteristics. These include the material particles size and shape, bulk density, moisture content, abrasiveness, friability, cohesiveness, hygroscopic, static charge, explosively, toxicity, melt point, and many others.
Next, consider how the system will fit into your location, plant, ship, barge or platform environment. How will the system’s planned pipeline routing and length fit into your installation area? Are there any physical constraints in the area, such as other equipment or spots with low headroom? What will it take to fit the system into your available area within these constraints? And how can the system be configured to provide easy maintenance access to system components? Especially on board of offshore rigs/ platforms, Platform Supply Vessels, Self-discharging cement carriers and other waterway bulk carriers space is limited, customised designs are therefore required.
Another major factor to consider is what material transfer rate the system must achieve to meet your application requirements.
Making a Choice
Assuming that your material can be pneumatically conveyed (that means, it doesn’t have a large particle size, a high bulk density and it isn’t extremely sticky), and without considering any other factors at this point, start by considering the conveying system with the lowest initial investment cost. In general this will be a dilute phase pneumatic conveying system.
Whether the dilute-phase system should operate under pressure or vacuum in your application depends on two main factors:
- Whether air leaking into or out of the system will have a negative effect: For instance, air leaking out of a pressure system that conveys a toxic or explosive material can create hazardous conditions in your application. In this case, a vacuum system would be a safer choice.
- Whether your material packs tightly (like wood shavings), is cohesive and tends to build up on surfaces (like titanium dioxide), or is fibrous (like some grain hulls): For materials like these, a vacuum system may be the better choice. This is because the vacuum in the conveying line tends to pull the particles apart during conveying rather than push them together or into the line walls as pressure conveying does.
But some factors may make a dense-phase conveying system better suited to your material (especially cement, fly ash, barite, Bentonite, etc.). The dilute-phase system re-lies mainly on providing a high enough air velocity to keep material entrained in the airstream. This relatively high velocity can damage a friable material, resulting in unacceptably high amounts of particle attrition. It can also de-blend a mixture of materials with different particle sizes and bulk densities. In both cases, the gentler conveying in a dense- phase system — which re-lies more on a high pressure differential than a high air velocity — is often a better option. The dilute-phase system’s high velocity can also be a problem for handling an abrasive material, which can quickly wear the conveying line and other components, making a dense-phase system the clear choice in this case.
Also consider a dense-phase conveying system when your system will include long conveying line runs. A dense- phase system typically requires a smaller line diameter than a comparably-sized dilute-phase system. This means that the dense-phase system not only requires less air volume but, in a long system, the smaller-diameter line sections are much lighter, making their installation and replacement easier. The dense-phase system’s smaller and lighter elbows and similar components provide the same advantages.
Choosing pressure or vacuum operation for your dense- phase conveying system depends on the same factors as for a dilute-phase system: whether air leaking into or out of the system will have a negative effect and whether your material packs tightly, is extremely cohesive and tends to build up on surfaces, or is fibrous.
Check our various solutions for several applications at www.lionbulkhandling.com. Lion provides customers with several dense phase system designs and options that can be built on board or at location. If you have any questions in regards to a dense phase solution for you application, contact us via http://www.lionbulkhandling.com/contact/ and fill in you project.
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