CBW Clyde Bergemann Wesel Rev. 5. Lean or Dense Phase? Selecting the most suitable pneumatic conveying system for handling Fly Ash

Transcription

1 CBW Clyde Bergemann Wesel Rev. 5 Lean or Dense Phase? Selecting the most suitable pneumatic conveying system for handling Fly Ash

2 Pneumatic Conveying Basic Principles Conveying System Components Material Air Feeder Air & Product Separator Air Types of Conveying System Continuous Batch Material Principles of Pneumatic Conveying 2

3 Pneumatic Conveying Basic Principles Positive Pressure Conveying System Product Air Blower / Compressor Feeder Air & Product Separator Air Product Principles of Pneumatic Conveying 3

4 Pneumatic Conveying Basic Principles Vacuum Conveying System Product Air Feeder Air & Product Separator Exhauster Air Product Principles of Pneumatic Conveying 4

5 Modes of Conveying Lean Phase / Dilute Phase Fully Suspended Flow Entrains the material in a high velocity air flow Can either be positive pressure or vacuum Pipe diameters must be large to achieve reasonable transfer rates Component and pipe wear is high because of the high transfer velocities Lower capital costs Energy consumption can be high Principles of Pneumatic Conveying 5

6 Modes of Conveying Dense Phase Material is transferred through the pipe in discrete plugs with pockets of compressed air in between Mostly positive pressure systems Velocity is much lower resulting in lower air demand & reduced pipe wear Pipes are much smaller than lean-phase Higher capital costs Energy consumption is low and usually directly proportional to the actual transfer rate Principles of Pneumatic Conveying 6

7 Modes of Conveying Principles of Pneumatic Conveying 7

8 Ash Transfer System Multiple options available depending on transfer capacity and conveying distance Wide range of vessels utilising the same key components Systems are bespoke designs targeted at customers specific requirements Robust design capable of conveying a wide range of particle distribution and composition Conveying aids available for problematic materials Before we can select the right technology we need to take into account the Fly Ash properties. Capability Presentation ~ Tractebel ~ Feb

9 Flyash properties Fuel Type ( Solid, Liquid, Gas) Boiler Type (PFB, CFB) Bulk Density Particle Size Distribution Moisture Content Flow Characteristics Chemical Composition Name of presentation 9

10 Flyash properties Particle Size Distribution Fine Flyash Course Flyash Fine Grit Coarse Grit d50 = mic d50 = mic d50 = mic d50 = mic Name of presentation 10

11 Geldart Classification Dense-Phase Pneumatic Conveying 11

12 Flyash properties Particle Shape Fine Fly Ash Sand Coarse Fly Ash Grit Fly Ash Name of presentation 12

13 Selection Criteria Selection criteria should include: Material Properties Pipe wear Energy consumption at all operating conditions Lifetime operating costs over at least 10 years Capital Cost Principles of Pneumatic Conveying 13

14 Dense Phase Options Used for short to medium distance conveying on multi collection hopper applications CLYDE Bergemann Ash Vessel Incorporates the World renowned Clyde Bergemann Dome Valve Principles of Pneumatic Conveying 14

15 Clyde Bergemann Ash Vessel Cast Vessel Low Cost Capable of conveying most Fly Ash & Grits Max conveying distance <500m Conveying rate <= 25tph at 200m. Principles of Pneumatic Conveying 15

16 Principles of Pneumatic Conveying 16

17 Used for long distance conveying on multi collection hopper applications CLYDE Bergemann MD-Pump Incorporates the World renowned Dome Valve Principles of Pneumatic Conveying 17

18 Clyde Bergemann MD-Pump Fabricated Vessel Capable of conveying Fine Fly Ash Max conveying distance <1000m Principles of Pneumatic Conveying 18

19 Principles of Pneumatic Conveying 19

20 Used for long distance high capacity conveying applications CLYDE Bergemann D-Pump Incorporates the World renowned Clyde Bergemann Dome Valve Principles of Pneumatic Conveying 20

21 Clyde Bergemann Double D-Pump Operating Cycle Start conveying Stop conveying Balance valve open Vent valve open Continuous air supply Vessel 1 conveying Vessel 2 filling Principles of Pneumatic Conveying 21

22 Pressure Clyde Bergemann D-Pump Intelligent Dome Valve Discharge Dome Valve fitted with valve positioner Partially open position controlled and modulated by logic controls based on attaining pipeline pressure set-point PLC Logic Control Panel Valve Positioner Pressure too high ~ valve partially closes Pressure too low ~ valve partially opens If blockage forms (causing pressure to continue to rise) ~ valve fully closes Pressure set-point Time Principles of Pneumatic Conveying 22

23 Principles of Pneumatic Conveying 23

24 Used for single and multi outlet fly ash handling and intermediate transfer systems CLYDE Bergemann PD-Pump Incorporates the World renowned Clyde Bergemann Dome Valve Principles of Pneumatic Conveying 24

25 Clyde Bergemann PD-Pump PD-Pump for high efficiency, single or multi outlet fly ash handling For conveying dry, fluidisable materials High transfer rates over medium to long distances High material : air ratio low air and power consumption High Volume Batch Transfer System Principles of Pneumatic Conveying 25

26 Principles of Pneumatic Conveying 26

27 Used to Transport Fine Ash from the Intermediate Silo to the Ash Storage Facility CLYDE Bergemann TD-Pump Incorporates the World renowned Clyde Bergemann Dome Valve Principles of Pneumatic Conveying 27

28 Principles of Pneumatic Conveying 28

29 Lean Phase Positive Pressure system Eductors Benefits Material Cheap and Cheerful. No fancy controls required. Low headroom requirement. No Cooling Water Requirement No Density Stablisers or Boosters Low capital cost. Name of presentation Compressed Air Drawbacks High conveying velocity, 15-30m/s. High wear of pipes & bends. Large bore pipes / large volume of low pressure transport air. Each Pickup point requires dedicated conveying line Close coupled dedicated blower. Very limited conveying distance. 29

30 Lean Phase Positive Pressure system Eductors APH Grit Handling System Name of presentation 30

31 Lean Phase Positive Pressure system Air Lock Vessels Low Pressure System Usually run from a 1 barg Roots Blower Non Coded vessels (cannot be used in EU) Can convey up to tph. Uses Hardened Cast chrome alloy pipes and bends with compression coupling. Capable of handling wide range of ash. (One system can handle ECO, APH & Flyash). No Cooling Water Requirement No Density Stablisers Lower capital cost. Very mature technology. Very Common in US & Asia Preferred choice of Korean EPC s Much Cheaper than Dense Phase systems. Name of presentation 31

32 Lean Phase Vacuum system Combination Collector/Filter An airlock is needed to transfer material from the vacuum system into the silo. Airlock BAGHOUSE SILO Vacuum Blower 32

33 Lean Phase Vacuum system Disc Swings Open (out of the ash flow stream) Swing Disc Closed Type HC Material Handling Valve 33

34 Lean Phase Vacuum system TYPE E Valve This valve works on the same, vacuum high and vacuum low principle as the swing valve but, it is specially designed for fine fluidisable materials. "Hg 0" 18" "Hg 0" 18" 34

35 Lean Phase Vacuum system Typical Advantages: Economical for one destination with many pick-up points. Vacuum systems leak inward (clean). Low headroom requirements at pick-up points. Capable of handling wide range of ash. (One system can handle ECO, APH & Flyash). Single pneumatic valve under each hopper. One I/O per valve Typical Disadvantages: limited to 200m distance max. Costly for multiple destination requirements. Vacuum is limited (~ 22 Hg/ 745 mbar), unlike pressure systems. Collector filter media limits ash temperatures to ~ 200 C. 35

36 Conclusions Dense Phase conveying has edge on high conveying rates and long distances. Capital cost is higher Maintenance cost is lower Running cost is lower Lean Phase conveying can handle most of the modern fly ash handling applications Capital cost is lower Maintenance cost is higher Power industry is price driven. Lean Phase conveying always has advantage on cost. Name of presentation 36

37 Thank You for Listening Dense-Phase Pneumatic Conveying 37