1.Methanol Flowsheets - A Competitive Review

2. Methanol is the simplest of the series of aliphatic alcohols. It is an extremely versatile chemical and is used as a raw material for a number of processes in the chemical industry. It may also be used unchanged as a solvent or cleaning fluid. Its largest single usage is oxidation to formaldehyde, itself a raw material used in the manufacture of synthetic resins for the wood, plastics, and paint industries. Methanol 3. Contents Haldor Topse Conventional Reforming Haldor Topse Combined Reforming Synetix LCM Lurgi Combined Reforming MGC Conventional Reforming MGC Combined Reforming MW Kellogg Conventional Reforming Uhde Conventional Reforming Uhde Combined Reforming 4. HDS Zinc Oxide Primary Reforming Heat Recovery Reformed Gas Fluegas Duct Compression Synthesis Distillation Main Processes 5. C/WC/W Oxygen Steam Steam Steam Demin Natural Gas Air Desulphurisation Secondary Steam LP Steam BFW Purge Steam Drum Product Fusel Oil RCB's MP Steam Process Condensate LPS LPS Converter Recycle Gas 6. Lurgi Steam Raising Converter Manway Manway Manway BFW InletBFW Inlet Steam Outlet Steam Outlet Exit Inlet 7. Benefits of Lurgi Steam Raising Converter Catalyst is on the tube side Optimized heat transfer area / catalyst volume Isothermal Mechanically complex Requires integration into the steam system Steam raised at a higher pressure than Adiabatic Bed Converters 8. Lurgi Equilibrium Profile 180 200 220 240 260 280 300 320 0 2 4 6 8 10 Temperature (C) MethanolConcentration(mol%) Max Rate Curve Methanol Equilibrium 9. Comparison of Tube Cooled, Linde and Lurgi Converters 25 mm 25 mm 25 mm Tube diameter 30 mm 10 mm 50 mm Tube pitch 70 mm 52 mm 100 mm Cat. vol/tube area 37 mm 72 mm 12.5 mm Volume utilised 83% 97% 23% TCC Linde Lurgi 10. Comparison of Linde and Lurgi Converters Linde converter has less heat transfer area Therefore cheaper Small catalyst operates along the maximum rate curve therefore converter smaller Linde can achieve 2000 tpd in one vessel Older Lurgi plants of 1000+ mtpd tend to have 2 converters Linde simple to manufacture Lurgi complex - tube sheet limits size of converter 11. Comparison of Linde and Lurgi Converters In Linde SRC gas flows across tubes Lurgi down inside tubes Linde converter easy to load Lurgi SRC has top have each tube loaded individually Must check pressure drops are equal as with a reformer Many tubes - 5000 per converter 12. Linde & Lurgi SRC's Compared to Toyo MRF Linde/Lurgi SRC's can raise steam at 35 to 40 bara Toyo MRF can raise steam at 28 to 32 bara Both can be used in reformer Toyo MRF catalyst runs at higher temperature Catalyst will deactivate slightly faster Toyo MRF is Radial flow Low converter pressure drop 13. There have been a number of instances where the welds between the tubes and the bottom tubesheet have failed During normal operation this is not a problem for the process side Syn gas does enter the steam system On shut down the reverse happens leading to catalyst damage 14. Some plants have reported high pressure drops across the catalyst in Lurgi converters Why ? Boiler Feed Water leaks Crushing of catalyst on start up and shut downs Catalyst is weak No clear reason 15. Natural Gas Sulphur Removal Saturator Reforming Air Condensate Compression BFW Demin Water CW CW Synthesis Distillation MP Steam Purge to Fuel Crude Methanol Product Methanol Fusel Oil Refining Column Bottoms HP Steam Synetix Low Pressure Methanol (LPM) 16. HP Steam Fuel Gas Hot Water BFW C/W Product Methanol Fusel Oil MP Steam BFW Cold Water Air Natural Gas MP Steam Refining Column Bottoms C/W 17. Click here to type slide reference BFW MP Steam BFW Cold Water Natural Gas Refining Column Bottoms HP Steam Fuel Gas Hot Water Air MP Steam C/W Product Methanol Fusel Oil C/W Secondary Oxygen 18. Click here to type slide reference WHB Air MP Steam Product Methanol Fusel Oil Natural Gas Purification BFWSteam Converter Purge to Fuel Expander C/W C/W Refining Column Bottoms Steam Drum 19. WHB Air MP Steam Product Methanol Fusel Oil Natural Gas Purification BFW Steam Oxygen Converter Purge to Fuel Expander C/W C/W Steam Drum 20. ManwayManway Manway Manway Manway Gas Out BFW Inlet Steam Outlet Feed Gas Inlet Diaphragm One Touch Coupler Flexible Hose Support Grid Outer Tube Catalyst Mitsubishi Superconverter 21. Inner Tube Outer Tube Catalyst Water/Steam Mixture Mitsubishi Superconverter 22. Mitsubishi Superconverter Benefits Integration of interchange and steam raising Complex converter consisting large number of tubes, a manifold, two tube sheets i.e. the worst features of a Lurgi SRC and a TCC Closely follows maximum rate line High conversion per pass - low recycle rate Raises 40 bar steam 23. Mitsubishi Superconverter Equilibrium Profile 180 200 220 240 260 280 300 320 0 2 4 6 8 10 Temperature (C) MethanolConcentration(mol%) Max Rate Curve Methanol Equilibrium 24. Click here to type slide reference MP Steam Natural Gas LP Steam BFW Air BFW to D/A BFW C/W Process CondySteam Raising Steam Raising BFW Heating Purge to Fuel Crude Fusel Oil Product Methanol Refining Column Bottoms Fuel HP Steam BFW C/W C/W 25. Multiple Adiabatic Bed Converters Different designs Typically multiple beds in multiple vessels Can be in one vessel Separate vessels for each bed Intercooling between beds BFW and steam raising 26. Multiple Adiabatic Bed Converters 30 bara steam raised and some BFW heating Vessels are cheap to manufacture as the walls are thin and all are same Large pipe size to minimize pressure drop More expensive than a quench converter due to pipework costs Jagged temperature profile Large number of equipment items Beds can be shallow; mal-distribution can be an issue Large loop interchanger 27. Adiabatic Bed Converter Equilibrium Profile 180 200 220 240 260 280 300 320 0 2 4 6 8 10 Temperature (C) MethanolConcentration(mol%) Max Rate Curve Methanol Equilibrium 28. Click here to type slide reference BFW Purge to Fuel C/W BFW Purification HP Steam Air Fuel Natural Gas Product Methanol Fusel Oil Refining Column Bottoms C/W Preheated Fuel Preheated Air BFW 29. BFW Purge to Fuel C/W BFWBFW Purification Air Fuel Natural Gas Product Methanol Fusel Oil Refining Column Bottoms C/W Preheated Fuel Preheated Air Secondary Oxygen 30. Comparison of Converter Types Rel. catalyst volume Number of vessels Vessel weight (tes) Vessel dia. (mm) Number of tubes Quench cooled 1.00 1 220 4700 - ARC 0.76 1 190 4700 - Tube cooled 0.74 1 210 4850 1840 Steam raising (F-T) 0.59 2 590 5800 11600 Adiabatic Bed 0.83 4 160 4750 - 31. Comparison of Converter Type Heat Exchanger Details Loop interchanger Crude cooler Sat. water heater Boilers Totals 31.9 36.0 32.1 - 100 Quench cooled 31.9 36.0 32.1 - 100 ARC 34.5 39.5 33.9 - 107.9 Tube cooled 78.3 37.3 - - 115.6 Steam raising (F-T) 87.3 34.8 - 37.3 159.4 Adiabatic bed 32. Relative Capital Cost of Loop Equipment Converter cost Total equipment cost (MPI) Total installed cost Quench 0.19 0.47 1.0 ARC 0.15 0.43 0.92 Tube cooled 0.16 0.44 0.90 Steam raising 0.49 0.82 1.36 Adiabatic bed 0.14 0.58 1.18