Novel Design of an Integrated Pulp Mill Biorefinery for the ...

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Table 6: Contaminant specification for cobalt FT synthesis, and cleaning effectiveness of wet and dry gas cleaning [79]. 2.4.3. Fischer-Tropsch Mechanism The heart of the Fischer-Tropsch reaction is present in the general form of: CO+2H2 → “-CH2-” + H2O ∆H298º=-165kJ / mol (2.4.3) In this reaction, syngas contain H2 and CO come together to form long chains of -CH2- .[75] There has been disagreement over the exact reaction and order of the reactions since the 34
invention of Fischer-Tropsch in the early 1930’s[80]. The reactions that are supposed to be occurring in the Fischer-Tropsch reactor are as follows: nCO + 2nH2 → CnH2n + nH2O (2.4.4) CO + 3H2 → CH4 + H2O ∆H298º=-247kJ / mol CO + H2O → CO2 + H2 ∆H298º=-41kJ / mol 2CO → C + CO2 ∆H298º=-172kJ / mol methanation (2.4.5) (water gas shift) (2.4.6) (Boudouard reaction) (2.4.7) H2 + CO → C + H2O (coke deposition) (2.4.8) Reaction 2.4.4 is the production of heavy hydrocarbons of varying chain length. This is the reaction that dominates when cobalt catalyst is used. Reaction 2.4.5 creates methane gas, which is sent with the offgas to turbines for power creation. Reaction 2.4.6 demonstrates the water gas shift, which creates the H2 to make up for an inadequate syngas ratio. The water gas shift reaction only occurs for the iron catalyst, requiring a lower temperature reaction. The Boudouard reaction creates carbon and CO2 , both undesirable products, that required cleaning. To avoid the creation of undesirable products, product selectivity must be utilized in the Fischer- Tropsch process. Product selectivity is accomplished through the use of temperature, pressure and catalyst. Generally, creation of long chain heavy hydrocarbons is accomplished by utilizing high pressures and low temperatures [4]. 2.4.4. Fischer-Tropsch Product Selection The equation that is accepted to predict the chain growth within Fischer-Tropsch synthesis is the Anderson-Schulz-Flory (ASF) distribution [4, 72, 75, 80, 81]. xCn = α n−1 (1−α ) (2.4.9) Where XCn is the molar yield in carbon number α is the chain growth probability factor, N is the length of the hydrocarbon. The “1- α” part of the equation describes the chance that chain growth will terminate [75]. To maximize wax production and thus to maximize FTD production, α should be as high as possible [4, 79]. A plot of the chain growth is given in Figure 9. 35
Page 1 and 2: Novel Design of an Integrated Pulp
Page 3 and 4: Table of Contents List of Figures .
Page 5 and 6: List of Figures Figure 1: Price of
Page 7 and 8: 1 Introduction The global transport
Page 9 and 10: 2 Background 2.1 Pulp Mill Backgrou
Page 11 and 12: 2.1.2.2 Chemical Pulping The most c
Page 13 and 14: sodium sulfide and sodium carbonate
Page 15 and 16: process described in the section on
Page 17 and 18: 2.2.1 Low-Temperature Black Liquor
Page 19 and 20: Figure 2: Chemrec gasification proc
Page 21 and 22: Table 3: Average syngas composition
Page 23 and 24: DME than that could be obtained fro
Page 25 and 26: U.S. Patent[58] and European Patent
Page 27 and 28: Figure 4: Topsøe gas phase technol
Page 29 and 30: DME Workshop, Japan (Sept. 7, 2000)
Page 31 and 32: 2.4.1. Fischer-Tropsch Reactors The
Page 33: kpH 2 pCO Cobalt rate = 2 (2.4.1) (
Page 37 and 38: Table 7: hydrocarbons and associate
Page 39 and 40: 3 Process Design 3.1 Pulp Mill 3.1.
Page 41 and 42: carbonate is fired in a lime kiln t
Page 43 and 44: lost and the pulp that provides tha
Page 45 and 46: Table 16: General operating paramet
Page 47 and 48: Table 19: Ash analysis of Pittsburg
Page 49 and 50: Table 22: Experimental syngas compo
Page 51 and 52: 3.2.5 Process Options and Flexibili
Page 53 and 54: Nitrogen compounds Nitrogen from th
Page 55 and 56: 3.3.2.3 Reactors A single-step gas
Page 57 and 58: Table 27: FT-diesel fuel synthesis
Page 59 and 60: 3.5.2 Power Generation Process Desi
Page 61 and 62: Figure 21: Schematic of biorefinery
Page 63 and 64: ar) reacts with the fuel in the com
Page 65 and 66: Figure 25showed the detailed energy
Page 67 and 68: 4. Design Summary The DME design an
Page 69 and 70: Figure 27: Mass and energy flow of
Page 71 and 72: References 1. Åhman, M., G. Modig,
Page 73 and 74: 42. R.A. Peascoe, J.R.K., C.R. Hubb
Page 75 and 76: PerformanceSimulation. 2006, Prince
Page 77 and 78: Appendix Appendix A MP Steam Demand
Page 79 and 80: Appendix B: Composite Fuel Blend to
Page 81 and 82: DME Density = 0.67 kg/L (at 20 °C)
Page 83 and 84: Air Separation Unit Requirements Ba
Page 85 and 86:
Purge gas: CO conversion is 60%, 40
Page 87 and 88:
Appendix D: FTD Synthesis Two diffe
Page 89 and 90:
Table D.3: The hydrocarbon product
Page 91 and 92:
Figure D.3 Mass and energy balance
Page 93 and 94:
Table D.3 Mass and energy balance o
Page 95 and 96:
Appendix E: Heat and Power Generati
Page 97 and 98:
Energy H2O absorbed MW 46.71 Using
Page 99 and 100:
Combustion 2CO+O2→ 2CO2 + 566 kJ/
Page 101 and 102:
Specific Heat (cp) b kJ/kgK 1.072 E
Page 103 and 104:
Specific Heat of Steam (cp) kJ/kgK
Page 105:
Appendix F: Concept Map 105
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