L&T-CHIYODA LIMITED Trays & Tower Internals An Overview for the Column Designer By Pramod Dixit L&T-CHIYODA LIMITED Trays & Packed Tower Systems WHY ?? For Distillation For Absorption For Extraction For Stripping For Reaction-Distillation L&T-CHIYODA LIMITED Hydraulics of column Vapour moving up ward Liquid moving down ward Driving forces: Pressure for vapour Gravity for liquid Column diameter is mostly controlled by Vapour (flow & pressure drop) L&T-CHIYODA LIMITED How It Works ?? Develop an Interface Between Liquid & Vapor Based on Their Fluid Properties Like : – Boiling Point – Absorption – Affinity to One or More Components L&T-CHIYODA LIMITED The Interface is Developed by Bubbling of Vapor Through a Pool of Liquid :Trays Bring Vapor in Contact With Liquid Spread Over Large Area : Packed Tower Systems L&T-CHIYODA LIMITED Tray -Family I st Generation - Channel Trays, Bubble Cap & Sieve Trays II nd Generation - Valve Trays of Various Types & Sizes III rd Generation - High Capacity Trays, Nye Trays, Multi-Downcomer Trays, Modified Valve Trays L&T-CHIYODA LIMITED The vapour bubbling mechanism Sieve Trays Bubble cap trays (Fixed cap) Valve trays (Floating cap) L&T-CHIYODA LIMITED Other Classification of Trays Based on Number of Passes : 1, 2, 3, etc. Collectors / Withdrawal Trays Heat Transfer Trays Disc & Donut Trays Baffle Shower Classification based on flow paths L&T-CHIYODA LIMITED L&T-CHIYODA LIMITED Normal tray configuration Bubbling area Non-bubbling area Downcomer area Bubble Cap Tray L&T-CHIYODA LIMITED L&T-CHIYODA LIMITED Four Pass Bubble Cap Tray Valve Tray L&T-CHIYODA LIMITED L&T-CHIYODA LIMITED Types of Valves L&T-CHIYODA LIMITED MULTI DOWNCOMER TRAYS Special Trays L&T-CHIYODA LIMITED Multi Downcomer Tray Multi Upcomer Extraction Tray Packing (Random) L&T-CHIYODA LIMITED I st Generation - Ceramic Berl Saddles, Ceramic Intalox Saddles II nd Generation - Metallic & Non-Metallic Packing, Pall Rings, Raschig Rings III rd Generation - High Capacity, Low Pressure Drop Packing : IMTP, CMR, etc. L&T-CHIYODA LIMITED Random Packing L&T-CHIYODA LIMITED STRUCTURED PACKING Gem Pack - (Glitsch) Mela Pack - (Sulzer) Intalox Others - (Norton) L&T-CHIYODA LIMITED Structured Packing L&T-CHIYODA LIMITED Mist Extractors / Demisters Purpose : Removal of Liquid Droplets From Vapor Streams How?? : – By Using Coalescing Property of Liquid to Metal Surface – By Change in momentum of Flow of the Stream L&T-CHIYODA LIMITED Types of Demisters Wire Mesh Type Vane type L&T-CHIYODA LIMITED Factors Which Decide Hardware Selection Service Conditions – Corrosion – Viscosity – Fouling Turndown Ratio Vapor Liquid Ratios Aeration Factors HETP, etc. L&T-CHIYODA LIMITED Types of Nozzles in the Column Process Nozzles - Feed / Withdrawal Utility Nozzles - Drain, Vent, Steam Flushing Manholes / Handholes Instrumentation / Control - PG, TG, LG, etc. L&T-CHIYODA LIMITED Loadings on Column Relief Valve Discharge Pipeline Reactions Trays & packings Live load of liquid on trays Process conditions (Pressure, Temperature) External conditions (Structurals, wind, seismic, vibration etc.) L&T-CHIYODA LIMITED Loading to be Considered on Account of Internals Approx. 120 Kg/m2 for Each Valves / Sieve Tray Approx. Riser Height * Liquid Density for Collectors Approx. Packing Height * Packing Density of Packed Towers Approx. Packing Height * 0.2 * Liquid Density for Liquid Hold-Up Approx. Weir Heights for Liquid Hold-up, Especially for Reboiler Feeds L&T-CHIYODA LIMITED Tolerances & their importance A - Tray Spacing : ± 3 mm B - Weir Height : ± 1 mm C - Flow Clearance Under Downcomer : ± 3 mm D - Downcomer Area / Chord Height : ± 1 mm to ± 6 mm Depending on Column Diameter E - Out of Levelness : ± 1.5 mm to ± 3 mm Depending Upon Tray Diameter Effect of Variations L&T-CHIYODA LIMITED A - Tray Spacing Downcomer Flooding or Tray Bypassing B - Weir Height Tray Efficiency & Pressure Drop C - Under Downcomer Flow Clearance D - Downcomer Area Tray Bypass or Downcomer Flooding E - Out of Levelness Can Cause Jet Flooding or Dumping Resulting in Loss of Efficiency & Product Quality Column Ovality Tray Mechanical Fitment Mismatch can Result in Reworking or Dislodging During Operation Reduction Can Cause Tray Flooding Increase Will Result in Loss of Active Area L&T-CHIYODA LIMITED Importance of Nozzle Orientation Feed Nozzle : to Feed at Desired Location Product Outlet Nozzle : to Take Product Out at Proper Elevation PG & TG : Proper Orientation / Elevation at Liquid or Vapor Zone as Required Manholes / Handholes : Ease of Entering the Column or Operability, Ease of Removal & Make-up Filling of Packing L&T-CHIYODA LIMITED Importance of Relative Orientations L&T-CHIYODA LIMITED Importance of Relative Orientations L&T-CHIYODA LIMITED Importance of Relative Orientations L&T-CHIYODA LIMITED THANK YOU