10 Considerations for Pneumatic Conveying System Design: What Most Engineering Schools Didn t Teach You

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1 10 Considerations for Pneumatic Conveying System Design: What Most Engineering Schools Didn t Teach You International Powder & Bulk Solids Rosemont, IL April 24-26, 2018 David Kennedy Business Development Manager VAC-U-MAX

2 Let s start our journey

3 What Most Engineering Schools Did Not Teach You Image courtesy of Psychologytoday.com

4 Typical Engineering School Curriculum: Fluids or Fluid Dynamics Materials or Materials Science Polymer Science Process & Plant Design AICHe Trade Shows such as Powder & Bulk Solids Other Educators: Jenike & Johanson Kansas State University (K-State) Bulk Solids Innovation Center The Wolfson Centre for Bulk Solids Handling Technology, School of Engineering at The University of Greenwich at Medway, Kent, UK

5 Vacuum Conveying System Basics Transfer of bulk dry powders and granules from a container to the customer s process using vacuum 3 Main components: 1) Pickup point 2) Material Convey Tubing 3) Filter Separator 4) Vacuum Tubing 5) Vacuum producer Mixture of conveying gas and powder (1-3) Clean air (3-5)

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7 Dilute Phase Vacuum Material is Entrained in Air Stream Up to 25,000 lbs/hr (11,000 kg/hr) Less then 300 ft (90m) convey distance Up to 6 (150mm) convey line

8 Why Vacuum conveying: Eliminating hand scooping If it leaks, it leaks inward Delivers the powder in a closed process from point A to B Discharges material with control Works with larger containers to reduce frequent container changes

9 10 things to know when designing a vacuum convey system 1. Bulk Density (#/ft3, PCF or gm/cc) Factor in calculating the size of the vacuum receiver (Can Velocity) Factor in calculating the size of the convey line vacuum power unit (Convey Velocity) Convey velocity must exceed saltation velocity gm/cc X = #/ft3 More velocity is not always better

10 10 things to know 2. Conveying Distance Horizontal and Vertical Number of 45- or 90-degree sweeps (CLR) One sweep = 20 feet of linear tubing or pipe For example: 20 Vertically + 20 horizontally and two 90-degree elbows Vertical legs: Beware of avalanches! A line clearing valve is recommended.

11 10 things to know 3. Convey Rate How many pounds per hour will be conveyed? Is it a batch operation? For example: customer wants to convey 2000 pounds per hour but they really want to convey 2000 pounds once an hour in 5 minutes. This is really 24,000 pounds per hour.

12 10 things to know 4. Material Characteristics One man s fumed silica Shape: Powder, Pastille, Pellet, Flake, or Granule Particle size / distribution Free Flowing? Moisture Absorption? Abrasive? Combustible? Chemically compatible?

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14 10 things to know 5. How Do You Receive The Raw Materials? Bag Fiber drums or barrels Bulk Bag a.k.a. Super Sac, FIBC RIBC (Rigid Intermediate Container) Silo/Day Bin Railcar Upstream process equipment

15 Bulk Bag Unloaders with enclosed vacuum convey line (left) and Bag Dump Stations with integral dust collectors (right)

16 10 things to know when designing a vacuum convey system 6. Is The Material Coming From Upstream Process Equipment? LIW or Weight-Loss Feeder Volumetric feeder Mixer Extruder Hopper Reactor Other equipment Up stream equipment effects down stream equipment => Know everything you can about your source.

17 10 things to know 7. Headroom How much headroom is above the equipment? Even the smallest vacuum conveying system for powders will require at least 30 of headroom. I m in over my head work-arounds: Cyclones or Filter-less Vacuum Receivers Scaling valves Positive pressure system

18 10 things to know 8. Batch Operation or Continuous Conveying Batch Operation: typical for extrusion process Continuous Operation: Volumetric or LIW feeder which then meter feeds the material continuously into the next process.

19 Vacuum Conveyor refilling weight-loss feeder via Discharge-On-Demand principal

20 10 things to know when designing a vacuum convey system 9. Geographic or Atmospheric Conditions? Anything that changes the density of the conveying medium Altitude: Denver CO or Mexico City vs. New Jersey Electrical: US vs. International Plant conditions: temperature controlled?

21 10 things to know 10. Material of Construction of the Equipment Mainly a product contact concern: Carbon Steel with coatings Stainless Steel: 304 or 316L Pharmaceutical Grade Aluminum Who cares? Maintenance and QC cares!

22 Basic components of a Vacuum Convey System Pick Up points Wands: Used in drums. Operator manipulation Great for minors Feedbins: Great for mixers or grinder output Bag Dump Stations Bulk Bag Unloaders. Great for automation of the system

23 Basic components Tubing or Flexible Hose Static grounding NFPA 77, 652, 654 Food-grade? Smooth-bore sweep elbows, couplings Metallic tubing.. aluminum or stainless steel no plastic! Aluminum on clean air side.

24 Basic components Filter Receiver A steep angled hopper will make sure the material discharges in mass flow 60- or 70-degree cones or 90-degrees! Hopper geometry: concentric, offset, tube-style Discharge opening / type: 50%+

25 A 90-degree cone??? Tube Hopper Tube hoppers are straight vacuum receiver, no cone. Best solution for non free flowing powders.

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27 Vacuum Conveying System Basics Transfer of bulk dry powders and granules from a container to the customer s process using vacuum 3 Main components: 1) Pickup point 2) Material Convey Tubing 3) Filter Separator 4) Vacuum Tubing 5) Vacuum producer Mixture of conveying gas and powder (1-3) Clean air (3-5)

28 Vacuum Source Venturi. Runs on compressed air. No moving parts. Simple. Low initial cost utility costs? Excellent for hazardous environments. Up-and-In up to 3,000lb/hr Basic components

29 Regenerative Blower Medium Vacuum, High Air Flow. Good for pellets and granules

30 Positive Displacement Vacuum Pump Straight-line Hg 16 Hg Great for conveying everything!

31 Basic components Controls Simple timer boards or pneumatic controls Automation and communication are the trends Local Mini PLC DCS PLC Based Know your area classification!

32 Basic components Air-To-Cloth Ratio Amount of air (CFM) moving through the system related to the amount of filter area (ft2) in the vacuum receiver. Lower air-to-cloth ratio means higher efficiency filtration and less HP requirement ( Face Velocity ) Can Velocity is.. Interstitial Velocity is. Permeability is ft3 / ft2 / min

33 Basic components Filter Elements Sock-type bag filters Pleated bags Cartridges Filter Media PTFE Static-Conductive SBPE Static-Conductive

34 A pleated bag filter has 5X more filter area than a sock-type filter bag/cage

35 Filter Maintenance and Access Top-Load with Swing-Away Cover (upper left) Top-Removal Filter Plate (center) Side Access Hinged Doors (right)

36 Types of Convey Systems for LIW Feeders Convey on Demand Discharge on Demand

37 Convey on Demand The feeder or process, in gravimetric and or volumetric mode, calls for material by sending a signal to the convey system to transfer and deliver material. Volumetric feeder signal: typically a level control.

38 Discharge on Demand Vacuum receiver is full of material and needs a refill The feeder or process sends a refill signal to the vacuum receiver. The vacuum system will then convey more powder to the vacuum receiver and will wait in standby mode until another refill signal is sent.

39 Design Factors that Affect the $$ of a Vacuum Conveying System Convey rate Material characteristics, including combustibility & chemical compatibility Sanitation or Cleanability Requirements Distance from pickup point to discharge point Electrical classification Overhead space above the process being fed Automation and/or communication Material handling Accuracy Elevation

40 Testing Materials and Powders Last but not least.. Get your powders evaluated by your pneumatic conveying equipment supplier before you place a purchase order. Have them run a full scale test. Don t rely on Google for your information!!! Don t skimp on value added items. These could make or break the system Remember your goal is to make more product to a high standard. The last thing you need is to tinker with the system. Make sure your supplier fully understands your goals.

41 Thank you for your time! Questions? Booth 1316 P&BS 2018 VAC-U-MAX 69 William Street Belleville, New Jersey USA Tel: VACUMAX