Pneumatic Conveying Equipment Testing

Aeration systems like pneumatic conveyors, vertical lifters or air slides are dominated by the air-particle interactions within the pipeline, which are numerous depending on mode of flow. In dilute or lean systems, this is dominated by lift, drag and collision forces. In dense particle laden flows, the air-particle interactions are much more complex and are largely dependent on the size distribution and density of the conveyed product.

At TUNRA Bulk Solids different test options are available to determine the conveying parameters required for reliable and optimised flow conditions.

Minimum Transport Conditions

One of the primary steps for designing and optimising all particle-air transport systems is determining the minimum transport velocity required to lift and convey the material through the pipeline or channel. This velocity as well as the steady-state flow conditions mainly depend on physical material characteristics such as density, bulk density, and flow mode. Initial characterisation of these velocities can be achieved through:

• Fluidisation and Permeability Tests:
  During permeability tests, the air flow rate flowing through a bed of bulk material of given depth is slowly increased until steady-state fluidisation pressure is reached and then decreased. The record of solids mass flow rate, bed depth and pressure loss per length allows the determination of minimum fluidisation velocity, permeability factor and steady-state fluidisation pressure. These results are utilised in air-slide conveying, mode of flow determination and fluidisation systems, like pneumatic feeders.

• Air-Retention and De-Aeration:
  During air-retention and de-aeration tests, the decrease of the pressure gradient is measured over the time during the de-aeration process. This test gives outputs of de-aeration time and de-aeration factor which can be used to determine how long the material remains aerated for transport analysis and also for mode of flow determination.

• Vertical and horizontal minimum Transport Tests:
  The minimum conveying velocity required to transport a given bulk material through the conveying pipeline needs to be determined for optimal design of pneumatic conveying systems and vertical lifters. Depending on the pipe orientation (e.g. vertical, horizontal), particle size and minimum mass flow rate required to lift and transport the particles, several sizes of the minimum transport chambers are available for testing at different orientations.

Assessment of probable Modes of Flow for Dense Phase Conveying

The procedure to determine the mode of flow likely to occur during pneumatic conveying of a given bulk material consists in two steps. The first step consists of determining the key physical particle and bulk characteristics of the material influencing its aeration behaviour. This includes determination of particle size distribution, particle density, loose poured bulk density, compressibility and tapped bulk density, as well as permeability and aeration / de-aeration tests. In a second step, predictive technique based on numerous flow charts is applied to determine the conveying mode of flow likely to occur.

• Flow Mode Visualisation:
  The flow mode can be visualised utilising a pneumatic conveying rig whose conveying section entirely consists of glass. In addition, conveying tests can be carried out in an industrial-scale pneumatic conveying system including a pipe section made of glass to visualise the flow mode. A standard camera or high-speed video camera can be used to record the flow.

• Full Scale Conveying Testing:
  Full scale pneumatic conveying tests are offered in a range of pipe diameter from 2 inches (53 mm) to 4 inches (100 mm) up to total conveying length over 180 meters. The tests allow accurate determination of conveying characteristics such as conveying velocity, solids mass flow rate and pressure loss along pipe sections of different configurations, i.e. straight pipes and bends. Test results can be used to predict conveying parameters for transport along both short and long distance with great accuracy.

Wear Analysis

With most particle transport systems, the particle and wall interaction will produce some type of wear to the wall surface and potentially degrade the particulate material. To characterise these wear and attrition processes, a number of test options are available:

• Abrasive Wear

• Determination of Wear Rate in specific Applications

• Wear Surface Characterisation for Wear Mechanisms Analysis

• Estimation of Component Life based on Wear Rate

• Selections of Materials for Maximum Component Life based on Wear Mechanisms and Wear Rate.

• Comparison of Wear Life of competing available Surface Materials

• Erosive Wear

• Determination of Wear Rate in Erosion Tester for Industry comparable Wear Situation.

• Erosion Testing at slow Speeds: 1-10 m/s (for particle size of 5mm – 50mm ) and high Speeds: 15-100 m/s for (1mm to 150 mm)

• Wear Surface Characterisation and Wear Mechanisms Analysis

• Estimation of Component Life based on Wear Rate

• Selections of Materials for maximum Life of Component based on Wear Rates

• Comparison of Wear Life of competing and available Surface Materials

• Particle Attrition

• Drop Tests according to industrial Requirements

• Determination of percental Degradation

• SEM Analysis for qualitative Assessment of Shape and Size Degradation

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