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PTEC 107 Process Science

PTEC 107 Process Science. Spring, 2012 Session 4 – General Chemistry Pt 2. Topics. Inorganic chemistry applications to process technology Analytical methods. Inorganic chemistry applications to process technology. Pulp and paper mills Refineries Energy Generation Food processing

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PTEC 107 Process Science

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  1. PTEC 107 Process Science Spring, 2012 Session 4 – General Chemistry Pt 2

  2. Topics • Inorganic chemistry applications to process technology • Analytical methods

  3. Inorganic chemistry applications to process technology • Pulp and paper mills • Refineries • Energy Generation • Food processing • Water and wastewater treatment

  4. Pulp and paper mills (Kraft mills)

  5. Chemistry for the Kraft mills • Cooking (digestion) • Oxygen delignification • Chlorine bleaching • Chemical recovery

  6. Pulp and paper mills (Kraft mills) Cooking or digestion – depolymerization by means of sodium sulfide and sodium hydroxide NaOH + Na2S + H2CO3 = NaHS + Na2CO3 + H2O

  7. Oxygen delignification

  8. Bleaching with chlorine

  9. Black liquor chemical recovery in a black liquor recovery furnace • Na2SO4 + 2 C → Na2S + 2 CO2 • Na2S + Na2CO3 + Ca(OH)2 ←→ Na2S + 2NaOH + CaCO3 • CaCO3 → CaO + CO2 • CaO + H2O → Ca(OH)2

  10. Black Liquor Recovery Furnace http://www.youtube.com/watch?v=QN1Ml8M7U8A

  11. Some refinery chemistry • Hydrodesulfurization • Hydrogen sulfide reaction with amines • Sulfur plant

  12. Hydrodesulfurization

  13. Hydrodesulfurization • C2H5SH + H2 → C2H6 + H2S • MoS catalytic hydrodesulfurization

  14. Reaction of H2S with amines • H2S + RNH2 (amine) = RNH3HS • Methyldiethanolamine (MDEA)

  15. Sulfur plant

  16. Claus process • 2H2S + 3 O2 → 2 SO2 + 2 H2O (step 1) • 2H2S + SO2 → 3S + 2H2O (step 2) • 2H2S + SO2 → 3S + 2H2O (overall reaction) • Other reactions on surface of catalyst • COS + H20 → H2S + CO2 • CS2 + 2H20 → 2H2S + CO2 • COS and CS2 are formed in the furnace

  17. Energy generation • Combustion • Hydrogen generation • Fuel cells

  18. Combustion

  19. Combustion • CnH2n+2 + (3n/2 + ½)O2 = nCO2 + (n+1)H2O (complete combustion) • CnH2n+2 + (n + ½)O2 = n CO+ (n+1)H2O (incomplete combustion)

  20. Hydrogen generation • Steam reforming: CH4 + H2O = CO + 3H2 or CH4 + 2H2O = CO2 + 4H2 • Water gas shift reaction: CO(g) + H2O(v) → CO2(g) + H2(g)

  21. Steam reforming

  22. Water gas shift system

  23. Fuel cells H2 + ½ O2 = H2O

  24. Fuel cells • Based upon combination of oxygen and hydrogen to make water and produce electricity • Different types of fuel cells (phosphoric acid, alkali, proton exchange membrane, etc.) • http://americanhistory.si.edu/fuelcells/basics.htm

  25. Water electrolysis 2H2O = 2H2 + O2

  26. Fuel cell driven car

  27. Battery electrolysis of water

  28. Hydrogen gas reservoir

  29. DC motor

  30. Electrolysis calculations • Hydrogen loses electrons, is oxidized, at the anode • Oxygen gains electrons, is reduced, at the cathode • To electrolyze 0.001 gram mole of water to produce 0.0005 gram mole of oxygen gas (O2) and 0.001 gram moles of hydrogen gas (H2) requires the transfer of one faraday of electricity (96.485 coulombs) • 0.001 gram mole of hydrogen is equivalent to 22.4 ml of gas at standard conditions • For a cell resistance of 20 ohms and a 3 volt battery, the current flow through the cell would be 3 V / 20 ohms = 0.15 A (0.15 coulombs/second). At this current flow, assuming 100% efficiency, it would take about 11 minutes to generate 22.4 ml of gas

  31. Food Processing • Sugar refining • Beer brewing • Sterilization

  32. Sugar beet processing

  33. Wastewater treatment • Primary treatment (physical separation) • Secondary treatment (biological oxidation) • Disinfection • Tertiary treatment (chemical treatment)

  34. Some tertiary treatment reactions • KAl(SO4)2 ·12H2O + 2Ca(OH)2 = Al(OH)3 + 2CaSO4 + KOH • Cl2 + H2O = HClO + HCl

  35. Analytical methods • Lab glassware • Water analysis • Physical • Chemical • Oil analysis • Physical • Chemical

  36. Lab Glassware • Beakers – used to contain liquids for mixing together and can be used for rough volume measurements • Pipette – used to deliver measured amounts of liquids into beakers and flasks • Burette – used to deliver measured amounts of liquids for titration • Crucible – used to dry or ash solids

  37. Water Physical Analysis • Color (comparison to color standards) • Turbidity (obscuration of light) • Measured in turbidity units (JTU, NTU) • Settleable solids (Imhoff cone) in ml solids/l liquid • Suspended solids (filter, dry solids at 103 deg C) measured as mg of solids per liter of liquid, mg/l • Dissolved solids (filter, dry filtrate at 103 deg C) mg/l • Volatile suspended solids (fire dry solids at 600 deg C) mg/l

  38. Turbidity and turbidimeters

  39. Settleable solids by Imhoff cone

  40. Suspended, volatile and dissolved solids

  41. Laboratory Chemical Analysis • Standard solutions used for analysis • pH measurement by electrodes • Alkalinity (carbonate and hydroxide content) • Hardness (calcium and magnesium concentrations) • < 50 mg/l is soft water • > 150 mg/l is hard water • Iron and manganese (cause color and stains) • Trace metals (zinc, arsenic, etc.)

  42. pH meter

  43. Hardness (total and calcium)

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