Considerations when sourcing Pneumatic Conveyors
When clients first consider Pneumatic Conveying as a method for handling bulk material and hear the principle of air blown into an enclosed pipe, they often expect the process to cause particle turbulence and potential damage. This initial view is far from the truth, if the right type of Pneumatic Conveying technology is specified for your process, as well as the material it will convey.
The purpose of this article is to outline the basic, but yet very important considerations, for when approaching a supplier to provide Pneumatic Conveying technology.
Types of Pneumatic Conveying
Pneumatic Conveying has predominately two category types – Lean Phase and Dense Phase Conveying.
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The type of conveying method chosen will determine how the materials travel through the process plant. Although the pipes are totally enclosed, through extensive process and formalised material characteristic testing, an understanding on how different materials react between the two types, can be demonstrated by an experienced supplier. There isn’t a ‘one process’ suits all.
With either Pneumatic Conveying categories, material is commonly transferred from a single collection point to either a single or multiple reception points and when installed as a full system, will include various components, such a range of pumps, valves and pressure vessels, depending on the material and distances conveyed.
Core Differences
Lean Phase
Lean Phase Conveying uses a large volume of air and higher velocity, to move in comparison, a small amount of material. As a result, the material is effectively carried through the pipe, while being suspended in air. Typically, this method is preferable for short distances and non-abrasive materials, either powdered or granular in nature.
The design of Lean Phase Conveyors offer the benefit of being compact, therefore utilising less space than Dense Phase Conveyors, as well as providing quicker installation. For the operator, the equipment is simple to use and carry out maintenance on – an important factor if the material handled causes regular ‘wear’.
Fragile materials that are conveyed through a Lean Phase Conveying system can often become degraded or damaged, leading to an increase in dust within the conveyor and also further down the process.
Depending on the process, this dust may change the properties of the material being conveyed, or become a potential explosion risk, often in both cases due to segregation. Such dust generation concerns can be mitigated or avoided by using a Dense Phase Conveyor.
Over a period of time, the higher conveying air velocity of Lean Phase Conveying may also cause ‘wear’ on the pipes if the material is not suited to this method of processing. When the wear is excessive, premature failure of the plant could occur, resulting often in lost production, environmental dust release and expensive maintenance.
With the correct application evaluation, it is possible to remove or mitigate all of these risks. It is therefore very important to seek consultation from a specialist who can confirm that the material handled is appropriate for this method of Pneumatic Conveying.
Other aspects to factor-in are the design of the pipeline and choice of bends and valves. Where possible, keep the pipeline simple and accessible. Quick access for cleaning and maintenance needs to form part of the overall layout.
Quality pipeline divertors, correctly selected for the application, such as the ProDV bypass valve or parallel tunnel diverter PT45 valve, will provide peace of mind on the exact, reliable control of the shut-off/supply of material.
Dense Phase
In comparison to the process of Lean Phase Convening, Dense Phase Conveying uses higher levels of pressure, but lower volumes of air, across a much longer pipeline.
Consequently, the material is pushed through the pipe and bends, in a slug/plug-like behaviour. This results in the material being conveyed at much lower velocities than Lean Phase Conveying – often of the order 3 to 5 times lower.
Dense Phase Conveying is suitable for a variety of materials, ranging from fine cohesive powders, abrasives such as pulverised coal through to coarse granular products.
One of the most important considerations for Dense Phase Conveying is ensuring the conveying velocity at the start is set correctly for the material being conveyed.
If the pressure and air volume is not set appropriately, it could lead to a poorly performing conveying system. Industrial scale conveying trials in pipelines with a bore of at least 80mm and a distance at least half of the intended distance for the users application, should be carried out to ensure a well-designed, long lasting system.
Typically, Dense Phase Conveyors experience minimal wear on the pipe and bends, allowing for less maintenance and long system life performance. Often the wear in Pneumatic Conveying Systems is quoted as being proportional to the velocity3.
For the case where the material is Dense Phase Conveyed on average at a velocity 5 times lower than the Lean Phase System, then the wear will be 53 = 125 times lower.
This is often over looked, but of course means that bends that last only 1 month in a Lean Phase System, could last 10 years in a Dense Phase one. Experienced providers will be able to assist the user with the correct choices according to the operating requirements.
Schenck Process UK is home to our Clyde Process Dense Phase Pneumatic Conveying systems, part of the ProPhase® range and are regarded as one of the world’s leading product brands for this technology.
What differentiates the Schenck Process range of Dense Phase Pneumatic Conveyors is the continued research and development of our products and solutions, a live and extremely busy industrial scale testing centre, as well as our 40-year experience in specialist design, testing and engineering.
All of this allows for: Simplicity, Reliability and Flexibility. In nearly all cases, each system is engineered to be bespoke to the process requirements, using standard, proven components, products and design approaches.
Before Schenck Process embark on any project, we will work with clients to truly understand their process needs, what issue they are encountering, what materials are handled, test the material characteristics and ensure we engineer a system that provides optimum performance and long-life operation.
- Full consultancy and engineered design
- Material and process inspection, as well as testing
- Introduce quality processes that removes a customer’s ‘anguish’
- UK, trusted Clyde Process product brand, supplied globally by Schenck Process
- Focused on offering efficiency, reducing maintenance and overall operational costs
- Project management available from start to finish – world wide
- Service packages and user training
Schenck Process is a global and trusted supplier of bulk handling industrial equipment, who support a variety of sectors including Food, Chemicals, Plastics and Pharmaceuticals. Mining, Steel & Metals, Sand & Gravel, Cement & Gypsum, Grain & Agriculture, Transport & Automation and Utilities.
Providing New Equipment, as well as Maintenance and Testing Services, with Systems for Conveying, Weighing, Feeding, Screening, Powered Processing, Automation, Air Filtration, Bag Filling & Discharging, as well as Components and Spares.
For more information on Schenck Process systems, please contact: enquiries@schenckprocess.co.uk | www.schenckprocess.com/uk
