Keep conveyor systems simple and efficient

The overriding economic mandate is one of simplicity and cost-efficiency.

By Doan Pendleton

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In choosing a system for safe, clean materials conveyance, it seems that the choices can be remarkably complex. Before choosing, a plant’s conveyor usually has human operators, open conveyor belts and implements such as buckets. While workers might be protected by proper clothing, masks and goggles, materials are exposed to air and dirt, waste is a constant worry, and particulates that endanger expensive equipment can slow or jam it. With constant economic pressures and attention focused on the bottom line, it’s mandatory that plant professionals seek alternatives and improvements such as pneumatic conveying systems. It seems so simple.

Since labor is one of the highest costs in a plant or facility, reducing man-hours becomes a primary target of any executive interested in reducing operating costs. A primary benefit of a pneumatic conveying system should be the reduction of man-hours. Where numerous workers were previously required to manipulate material, there might now be the need for only one to add material at the front end of the process.
Since labor is one of the highest costs in a plant or facility, reducing man-hours becomes a primary target of any executive interested in reducing operating costs. A primary benefit of a pneumatic conveying system should be the reduction of man-hours. Where numerous workers were previously required to manipulate material, there might now be the need for only one to add material at the front end of the process. (VAC-U-MAX)

Why, then, does evaluating the options for pneumatic conveying systems appear to require an engineering degree? Even engineers are going to have a hard time answering questions such as:

  • Should the system be dilute phase or dense phase?
  • Should the system be vacuum, pressure or combination?
  • Given the physical properties of your materials, how exactly will they be best conveyed?
  • What’s the friction factor of your solids?
  • How do you calculate the expected losses of pressure throughout the system?
  • Given that some chemicals are oxygen sensitive, what gas should you use?

It gets worse when you have to figure in factors such as gas densities and solids velocity in horizontal, diagonal and vertical pipe runs.

Okay, hold up

Take a deep breath and a giant step back. Remember the original reasons for wanting to do this in the first place. Those reasons are relatively simple and, fortunately, so are the choices involved. In evaluating a pneumatic conveying system, you want three pieces of information:

Is the system going to truly automate a process? If a particular process now involves five workers, can most or all of those people be assigned to more productive activities elsewhere? Will it be possible to run the process with little to no attention, save perhaps periodic monitoring?

Is the system reliable? Will the system run continuously without babysitting? Will it stand up to the required process; is it robust and seriously proofed against breakdowns? How much maintenance will it require?

What is the system cost? A system’s installed cost is only the beginning of the answer. How quickly would the system pay for itself? How much time and cost will its implementation save?

An understanding of material characteristics is essential when designing a vacuum transfer system.

– Doan Pendleton

These questions are interrelated, and each must be answered in detail. Fortunately, if you use reliable expert assistance, you won’t need to answer that first set of horribly niggly engineering-type questions. These important questions can be answered fully by an outside expert and to your satisfaction.

An understanding of material characteristics is essential when designing a vacuum transfer system. Experts often possess data about a particular substance’s behavior and will test it within a proposed configuration to ensure it conveys properly. Sometimes this knowledge must be extensive. For example, often several product grades within the same product group might have completely different characteristics such as free-flowing, sluggish or non-free flowing. One grade of zinc oxide might be dry and free-flowing while another grade might be more cohesive and adhere to the inside of conveying tubes. Pneumatic conveying experts are skilled in designing custom solutions based on application-specific requirements.

Pneumatic systems convey material from closed hoppers through closed lines and require little to no intervention.
Pneumatic systems convey material from closed hoppers through closed lines and require little to no intervention. (VAC-U-MAX)

A pneumatic conveying vendor that routinely designs and builds custom pneumatic conveying systems most likely will know how to tailor a system to meet your present and future needs. There’s a possibility that the design can work properly out of the box. The better vendors of pneumatic equipment have large-scale testing facilities that can confirm material flowability and system capacity using materials specific to your application.

Implementing an appropriate pneumatic conveying system — or correctly expanding an existing system — yields numerous benefits. Switching to a pneumatic conveying system is a simple solution that might yield amazing cost benefits.

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