Integrated Syngas Fermentation Process and System

• US 20110138684A1
• Filed: 12/10/2009
• Published: 06/16/2011
• Est. Priority Date: 12/10/2009
• Status: Abandoned Application

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: KRANZ, David R.
• Application Number:
  US12/635,432
• Publication Number:
  US 20110138684A1
• Time in Patent Office: Days
• US Class Current: 44/451
• CPC Class Codes: C10G 2300/1011 Biomass
• CPC Class Codes: C10J 2300/0916 Biomass
• CPC Class Codes: C10J 2300/0969 Carbon dioxide
• CPC Class Codes: C10J 2300/1659 to liquid hydrocarbons Fischer-Tropsch process C10G2/00
• CPC Class Codes: C10J 2300/1665 to alcohols, e.g. methanol or ethanol preparation of alcohols in general C07C29/00
• CPC Class Codes: C10J 2300/1681 with biological plants, e.g. involving bacteria, algae, fungi
• CPC Class Codes: C10J 2300/1815 for carbon dioxide
• CPC Class Codes: C10J 3/463 in stationary fluidised beds
• CPC Class Codes: C10L 1/02 essentially based on components consisting of carbon, hydrogen, and oxygen only
• CPC Class Codes: C12M 21/04 for producing gas, e.g. biogas digesters for manure with production of biogas A01C3/028, biological treatment of water, waste water or sewage C02F3/00, C02F11/02, preparation of natural gas or syngas C10L3/06, C10L3/10
• CPC Class Codes: C12M 21/12 for producing fuels or solvents C12M21/04 takes precedence; liquid carbonaceous fuels C10L1/00, solid fuels C10L5/00
• CPC Class Codes: C12M 25/20 Fluidized bed in chemical or physical processes B01J8/18
• CPC Class Codes: C12M 29/24 Recirculation of gas
• CPC Class Codes: C12P 7/065 with microorganisms other than yeasts
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: C12P 7/14 Multiple stages of fermentation; Multiple types of microorganisms or re-use of microorganisms
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02P 20/145 the feedstock being materials of biological origin
• CPC Class Codes: Y02P 30/20 using bio-feedstock

Abstract

In some embodiments, the present invention relates to methods (processes) of syngas fermentation involving an integral gasification process, and to corresponding systems for carrying out or implementing such methods. In such methods and systems of the present invention, carbon dioxide (CO₂) produced during the fermentation of syngas is directed into the gasifier (e.g., as a motive gas or component thereof) where it enhances carbon monoxide (CO) production and mitigates char production.

Claims

1. A method for generating ethanol from biomass, said method comprising the steps of:

a) gasifying biomass to generate a syngas mixture comprising CO, CO₂, and H₂;

wherein the gasifying is carried out in a fluidized bed gasifier using a motive and reactive gas stream comprising a mixture of gases;

b) fermenting at least a majority of the syngas mixture to produce ethanol via a fermentation process driven by a population of microorganisms, wherein CO₂ is produced as a by-product of the fermentation; and

c) directing at least a majority portion of the CO₂ produced during the fermenting step into the gasifying step so as to;

i) contribute as a component of the motive and reactive gas in the fluidized bed gasifier; and

ii) enhance the gasifying step, via an equilibrium shift, so as to increase the production of CO and decrease the production of char.

2. The method of claim 1, wherein the step of directing involves a separation sub-process for separating CO₂ from other fermentation products.

3. The method of claim 2, wherein a pressure swing adsorption O₂ generator is used to supply an O₂ component to the motive and reactive gas stream.

4. The method of claim 3 further comprising a step of channeling a portion of the CO₂ produced during the fermenting step to a photosynthetic sub-process for generating biomass.

5. The method of claim 4, wherein the biomass generated by the photosynthetic sub-process is directed into the gasifying step.

6. The method of claim 1, wherein the biomass is preprocessed prior to it being gasified in the step of gasifying.

7. The method of claim 1, wherein the biomass is selected from the group consisting of wood, sorgum, rice straw, switchgrass, jatropha, algae, corn, sugarcane, and combinations thereof.

8. The method of claim 1, wherein a deliberate effort is made to minimize N₂ content in the motive and reactive gas stream mixture.

9. The method of claim 1, wherein the microorganism population used to drive the fermentation of the fermenting step comprises microorganisms selected from the group consisting of Clostridium ljungdahlii, Clostridium autoethanogenum, and Clostridium carboxidivorans P7^T.

10. The method of claim 1 further comprising a step of blending the produced ethanol with fuel to yield a blended fuel.

11. The method of claim 1 further comprising a step of synthesizing hydrocarbons via Fischer-Tropsch synthesis with a portion of the syngas produced in the step of gasifying.

12. The method of claim 11, wherein the hydrocarbons synthesized via the Fischer-Tropsch synthesis comprise Fischer-Tropsch product species operable for use as synfuels, and wherein such species are blended with the produced ethanol to yield a blended synfuel.

13. A system for generating ethanol from biomass, said system comprising:

a) a source of biomass amenable to gasification;

b) a fluidized bed gasifier in processible communication with said source of biomass and operable for gasifying said biomass, and comprising an integral heating means;

c) a motive and reactive gas mixture supply and stream in processible communication with said fluidized bed gasifier, wherein the motive and reactive gas is operable for reacting with the biomass in the gasifier to yield a syngas mixture;

d) a fermenting chamber comprising a population of microorganisms suitable for effecting the fermentative transformation of syngas to a fermentation product comprising ethanol and CO₂, wherein said fermenting chamber is in processible communication with said gasifier such that it can receive the syngas produced therefrom; and

e) a separator in processible communication with said fermenting chamber, wherein said separator is operable for separating CO₂ from a residual fermentation product balance, and wherein said separator is in processible communication with the motive and reactive gas mixture supply and stream such that at least a majority of the CO₂ produced in the fermenting chamber is incorporated as a component of the motive and reactive gas mixture supply and stream.

14. The system of claim 13 further comprising a photosynthetic biomass growth chamber, wherein said photosynthetic biomass growth chamber is in processible communication with the separator such that it is functionally operable for receiving a portion of the CO₂ produced in the fermenting chamber, and wherein it utilizes this CO₂, together with radiant energy, to grow biomass.

15. The system of claim 14, wherein said photosynthetic biomass growth chamber is placed in processible communication with the gasifier, such that at least a portion of the biomass grown in the photosynthetic biomass growth chamber can be directed into the gasifier.

16. The system of claim 15 further comprising a pressure swing adsorption generator, wherein said pressure swing adsorption generator is in processible communication with the motive and reactive gas mixture supply and stream, and wherein it is operable for supplying an O₂ component of the motive and reactive gas mixture supply and stream.

17. The system of claim 16 further comprising a biomass pre-processing unit operable for pre-processing at least some of the biomass being fed into the gasifier, and further operable for rendering the biomass more amenable to gasification.

18. The system of claim 17, wherein said system is engineered and corresponding operated so as to minimize the N₂ content of the motive and reactive gas mixture supply and stream.

19. The system of claim 13 further comprising a blending unit, said blending unit being in processible communication with the fermenting chamber and operable for blending at least a portion of the alcohol produced in said chamber with a fuel to yield a blended fuel.

20. The system of claim 13 further comprising a Fischer-Tropsch synthesis chamber in processible communication with said fluidized bed gasifier, such that a portion of the syngas produced in said gasifier can be directed to the Fischer-Tropsch synthesis chamber where it can be processed into synfuel.