How to use Industrial Dilute-Phase Positive Pressure Pneumatic Conveying Calculator
- Enter Powder Design Mass Throughput (t/h) and adjust the options as needed.
- Run the tool and inspect its results, evidence and limitations.
- Copy or download the result, then verify it against the actual website, source data or business records.
Try a concrete example
In a flour mill conveying starch powder at 15.0 t/h (4.17 kg/s) to storage silos across 80m horizontal equivalent length and 15m vertical lift (including 4 x R=1.5D elbows) with 1400 kg/m³ true density and 150 μm d50, using solids ratio μ = 8.0 kg/kg: Rizk correlation gives saltation velocity of 12.1 m/s, yielding 21.8 m/s design operating velocity (within the 18 to 25 m/s dilute phase window); recommended pipe is DN150 (6-inch, ID 154 mm); required free air delivery is 14.5 m³/min (853 CFM, 0.52 kg/s gas flow); total two-phase pressure drop is 38.6 kPa (11.2 kPa clean gas friction, 16.5 kPa particle suspension friction, 5.4 kPa acceleration drop, and 5.5 kPa gravitational lift); recommended Roots blower motor is 18.5 kW (blower discharge at 140.0 kPa absolute, 13.8 kW shaft power with solid reserve), ensuring fully suspended flow and zero line clogging.
How to interpret results
Dilute-phase pneumatic conveying is widely used across food grains, plastic resins, chemicals, cement, and fly ash handling. The physical principle relies on high-velocity gas streams to continuously entrain and suspend particulate solids through enclosed pipelines. Two-phase fluid mechanics calculations comply strictly with Klinzing models and the Rizk saltation correlation. A critical engineering constraint is maintaining actual in-line gas velocity strictly above the particulate saltation velocity (v_salt). If velocity falls below saltation, solids settle along the pipe bottom, choking cross-sectional area and causing rapid line blockage. Systems operate with solids loading ratios between 5 and 15 kg solids/kg air and velocities between 18 and 25 m/s. Total pressure drop sums clean gas friction, solids acceleration, suspension friction, and vertical hydrostatic lift. Sizing pipe diameter and blower pressure head guarantees reliable conveying without line choking or excessive abrasive wear.
Frequently asked questions
Why is saltation velocity the critical threshold for preventing pipeline plugging in pneumatic conveying?
Saltation velocity (v_salt) is the minimum superficial gas velocity required in a horizontal pipe below which entrained solid particles fall out of suspension and deposit along the pipe bottom. Deposited solids constrict the flow area, triggering rapid pressure spikes and full line plugging until the blower relief valve lifts or the motor trips. Design air velocity must remain 1.3 to 1.5 times saltation velocity (18 to 25 m/s) throughout the entire pipeline.
What are the primary differences between dilute phase and dense phase pneumatic conveying?
First, solids loading ratio (μ): dilute phase uses lower ratios (3 to 15 kg solids/kg gas) with particles dispersed in suspension; dense phase uses high ratios (25 to 80+ kg solids/kg gas) with materials moving as plugs or sliding dunes. Second, velocity and pressure drop: dilute phase operates at high velocity (18 to 25 m/s) with moderate pressure drop (30 to 80 kPa, powered by Roots blowers); dense phase operates at low velocity (4 to 8 m/s) with high pressure (200 to 500 kPa, powered by air compressors and pressure vessels). Third, material suitability: dilute phase suits non-friable materials over moderate distances (flour, starch, plastic pellets); dense phase suits friable pellets or highly abrasive mineral ores.
Why are pipe elbows the most vulnerable zones for abrasive wear and pressure drop in pneumatic conveying?
When a two-phase gas-solid stream negotiates a 90° elbow, particle inertia prevents solids from following turning streamlines, driving them straight into the outer bend wall: First, severe impact erosion: abrasive particles (quartz sand, fly ash) can pierce carbon steel elbows within weeks; wear-resistant ceramic tile linings or induction-bent long-radius sweeps (R/D ≥ 5 to 10) are required. Second, velocity deceleration and re-acceleration pressure drop: particle kinetic energy is dissipated upon impact, forcing the expanding gas stream to re-accelerate slowed solids downstream; one standard bend typically imparts resistance equivalent to 8 to 15 meters of straight pipe.
Why are positive-displacement Roots blowers standard for dilute phase conveying rather than centrifugal fans?
Roots blowers possess positive displacement characteristics where delivered volume remains virtually independent of backpressure. In contrast, centrifugal fan airflow drops steeply as system resistance rises; when momentary material surges increase line resistance, a centrifugal fan loses flow, dropping velocity below saltation and choking the pipe. A tri-lobe Roots blower continues displacing constant air volume even if pressure rises from 30 to 60 kPa, generating positive clearing thrust to purge localized particle accumulations.