C2 Acetylene Hydrogenation

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Acetylene Hydrogenation - Consultancy
Ethylene Plant Flowsheets
Placement of Acetylene Hydrogenation Reactor
Cracker Feedstock / Product Variability
Acetylene Reactor Feeds
Reasons for Acetylene Removal
Reacting Components and Conditions
Reactor Operation and Reacting Components
Reactor Design
Selectivity vs. Temperature and Ethane Formation
Effect of CO
Poisons
Green Oil
Turndown
H/D Ratio and Pressure Drop
Thermocouple Placement
Start-up
Problems During Start-up
Shut Down
Regeneration
Catalyst Experience, Problems and Other Information
Front End / Tail End Comparison

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C2 Acetylene Hydrogenation

  1. 1. C2PT Catalyst Process Technology C2 Acetylene Hydrogenation
  2. 2. Ethane usually recovered from natural gas fields mainly USA Propane/butane recovered from gas fields middle east, Texas etc. Kuwait has a large butane recovery system. Also can come from LNG plants Refinery naphtha / condensate C5 to C7 paraffin based low octane naphtha from refineries also from natural gas / oil well head production Light and heavy gas oils refinery based (200 to 350°C) AGO and (350 to 550 °C) VGO The more paraffinic the feedstock the higher the ethylene yields and the greater the value of the co-products Feedstock Sources
  3. 3.  Sulfur Cracks in furnaces to give H2S and COS. Mercaptans in C3/C4 cuts, RSH and thiophenes in gasoline, benzo-thiophenes in fuel oil  Arsenic Organic or arsine Makes arsine in the furnaces and some remains as organic  Mercury Metallic / organic Decomposes to metallic some remains as organic  Ballast water Sea water from shipping feed stock Metals Nickel, sodium, vanadium, iron from heavy feedstocks FCCU off gas (gas compressor suction, developing trend) NOx, H2S, amines, SbH3, As , COS, O2, CO2 plus others Major Feedstock Impurities
  4. 4. Base Intermediate Final C2H2 + H2 = C2H4 + H2 = C2H6 C2H2 = CH2 CH CH CH2 Butadiene = Green oil CH3 C CH + H2 Methyl Acetylene = CH3 CH CH2 propylene CH2 C CH2 + H2 Propadiene = CH3 CH CH2 propylene CH2 CH CH CH2 + H2 Butadiene = CH3 CH CH2 Butylene CH2 CH CH CH2 Butadiene = Green oil Relative reactivities C2H2 > C4H6 > C3H4 (MA) >> C3H4 (PD) > C2H4 Acetylene Basic Chemistry
  5. 5. Conventional Ethylene Flowsheet
  6. 6. Cracking Furnaces Quench Compression Stages 1-3 Caustic Scrubber Compression Stage 4 Dry Figure 1. Simplified Ethylene Flowsheet Cracking/Preliminary Clean-Up Fuel Oil Gasoline CO2 H2S H2O H2 CO C1 C2 C3 C4 C5+ * * - Possible C2H2 hydrogenation step, normally called wet gas stream
  7. 7. Front End Systems
  8. 8. H2 CO CH4 C2H2 C2H4 C2H6 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10 C5+ Figure 2. Front End De-Ethanizer C3H4 C3H6 C3H8 C4H6 C4H8 C4H10 C5+ DE-ETHANISER DE-METHANISER C2SPLITTER H2 CO CH4 C2H4 C2H6 Acetylene Hydrogenation Reactor Recycled to Cracking Furnaces ( Pd on alumina)
  9. 9. H2 CO CH4 C2H2 C2H4 C2H6 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10 C5+ C4H6 C4H8 C4H10 C5+ DE-PROPANISER DE-METHANISER DE-ETHANISER H2 CO CH4 C3H4 C3H6 C3H8 C2SPLITTER Figure 3. Front End De-Propanizer Acetylene Hydrogenation Reactor C2H4 C2H6 Recycled to Cracking Furnaces ( Pd on alumina)
  10. 10. DE-METHANISER DE-ETHANISER C2SPLITTER H2 CO CH4 C2H2 C2H4 C2H6 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10 C5+ H2 CO CH4 C3H4 C3H6 C3H8 C4H6 C4H8 C4H10 C5+ Acetylene Hydrogenation Reactor H2 CO Figure 4. Tail End De-Ethanizer C2H6 Recycled to Cracking Furnaces C2H4 ( Pd on alumina)
  11. 11. Ethylene Plant Flowsheets Placement of Acetylene Hydrogenation Reactor Cracker Feedstock / Product Variability Acetylene Reactor Feeds Reasons for Acetylene Removal Reacting Components and Conditions Reactor Operation and Reacting Components Reactor Design Selectivity vs. Temperature and Ethane Formation Effect of CO Poisons Green Oil Turndown H/D Ratio and Pressure Drop Thermocouple Placement Start-up Problems During Start-up Shut Down Regeneration Catalyst Experience, Problems and Other Information Front End / Tail End Comparison Acetylene Hydrogenation

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