Model predictive control of fermentation temperature in biofuel production

• US 7,831,318 B2
• Filed: 10/30/2007
• Issued: 11/09/2010
• Est. Priority Date: 10/31/2006
• Status: Expired due to Fees

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Tay, Michael E., Noll, Patrick D., Macharia, Maina A., Bartee, James F.
• Primary Examiner(s): Borin; Michael
• Assistant Examiner(s): HARWARD, SOREN T
• Application Number:
  US11/928,344
• Publication Number:
  US 20080108048A1
• Time in Patent Office: 1,106 Days
• Field of Search: 4352891-3094, 422105-116
• US Class Current: 700/29
• CPC Class Codes: G05B 13/048 using a predictor

Abstract

A system and method are provided for controlling temperature of a batch fermenter in a biofuel production process. A nonlinear predictive integrating temperature model for a batch fermentation process is provided that is a function of fermenter level. An objective for the batch fermentation process specifying a target fermenter temperature for the batch fermentation process is received, as is process information for the batch fermentation process, including fermenter level and fermenter temperature. The nonlinear predictive integrating temperature model is executed in accordance with the objective using the process information as input to determine target values for manipulated variables for controlling fermenter temperature of the batch fermentation process. The fermenter temperature for the batch fermentation process is controlled in accordance with the target values to produce biofuel in accordance with the objective, to substantially optimize the end of batch biofuel yield.

Claims

1. A method of controlling the temperature of a batch fermenter in a biofuel production process, comprising:

providing a nonlinear predictive integrating temperature model for a batch fermentation process, wherein the nonlinear predictive integrating temperature model is a function of the volume of the fermentation mash, and

models the dependence of fermenter temperature on fermentation feed temperature when the volume the of fermentation mash is below a designated level, and

models the dependence of fermenter temperature on cooling water valve settings of a cooling exchanger when the volume of the fermentation mash is above the designated level;

receiving an objective for the batch fermentation process specifying a target fermenter temperature for the batch fermentation process;

receiving process information for the batch fermentation process, comprising the volume of the fermentation mash and fermenter temperature;

executing the nonlinear predictive integrating temperature model to achieve the objective using the process information as input thereby determining a target fermentation feed temperature or a target cooling water valve setting; and

adjusting the fermentation feed temperature in accordance with the target fermentation feed temperature when the volume of the fermentation mash is below the designated level; and

adjusting the cooling water value settings of the cooling exchanger in accordance with the target cooling water valve setting when the volume of the fermentation mash is above the designated level.

2. The method of claim 1, wherein the nonlinear predictive integrating temperature model further models heat balance of the fermentation process, comprising a balance between available cooling and current fermentation heat generation.

3. The method of claim 1,

wherein the nonlinear predictive integrating temperature model further models a relationship between cooling water supply temperature and batch fermenter temperature, wherein the nonlinear predictive integrating temperature model is operable to predict the impact of cooling water supply temperature on fermenter temperature;

and

wherein the target values comprise a change in a cooling water valve setting to preemptively maintain fermentation batch temperature against disturbances in cooling water supply temperature.

4. The method of claim 1, wherein the nonlinear predictive integrating temperature model further models metabolic activity of yeast in the batch fermentation process as function of one or more of:

ethanol concentration;

sugar concentration;

enzyme concentration;

batch time;

or

integrated cooling quantity; and

wherein the target values are determined based at least in part on the modeled metabolic activity of yeast in the batch fermentation process.

5. The method of claim 1;

further comprising;

repeating said receiving process information, said executing the nonlinear predictive integrating temperature model, and said controlling in an iterative manner to substantially optimize biofuel production over a fermentation batch.

6. The method of claim 1;

wherein the target temperature comprises a target temperature trajectory for the fermentation batch.

7. The method of claim 1, further comprising receiving constraint information specifying one or more constraints for the biofuel production process, wherein said executing the nonlinear predictive integrating temperature model comprises determining the target values subject to the one or more constraints.

8. A system for controlling the temperature of a batch fermenter in a biofuel production process, comprising:

a fermenter,

at least one processor coupled to the fermenter; and

at least one memory medium coupled to the at least one processor, wherein the at least one memory medium stores;

a nonlinear predictive integrating temperature model for a batch fermentation process, wherein the nonlinear predictive integrating temperature model is a function of the volume of the fermentation mash, and—

models the dependence of fermenter temperature on fermentation feed temperature when the volume of the fermentation mash is below a designated level, and

models the dependence of fermenter temperature on cooling water valve settings of a cooling exchanger when the volume of the fermentation mash is above the designated level;

program instructions that, when executed by the processor, cause the processor to;

receive an objective for the batch fermentation process specifying a target fermenter temperature for the batch fermentation process;

receive process information for the batch fermentation process, comprising the volume of the fermentation mash and fermenter temperature;

execute the nonlinear predictive integrating temperature model to achieve the objective using the process information as input thereby determining a target fermentation feed temperature or a target cooling water valve setting;

adjust the fermentation feed temperature in accordance with the target fermentation feed temperature when the volume of the fermentation mash is below the designated level; and

adjust the cooling water value settings in accordance with the target cooling water valve setting when the volume of the fermentation mash is above the designated level.

9. A method of controlling the temperature of a batch fermenter in a biofuel production process, comprising:

providing a nonlinear predictive integrating temperature model for a batch fermentation process, wherein the nonlinear predictive integrating temperature model is a function of the volume of the fermentation mash, and

models the dependence of fermenter temperature on fermentation feed temperature when the volume of fermentation mash is below a designated level, and

models the dependence of fermenter temperature on fermenter cooling exchanger return temperature when the volume of fermentation mash is above the designated level;

receiving an objective for the batch fermentation process specifying a target fermenter temperature for the batch fermentation process;

receiving process information for the batch fermentation process, comprising the volume of the fermentation mash and fermenter temperature;

executing the nonlinear predictive integrating temperature model to achieve the objective using the process information as input thereby determining a target fermentation feed temperature or a target cooling exchanger return temperature,

adjusting the fermentation feed temperature in accordance with the target fermentation feed temperature when the volume of the fermentation mash is below the designated level, and

adjusting the cooling exchanger return temperature via a cascaded controller when the volume of the fermentation mash is above the designated level, wherein the cascaded controller determines a target cooling water value setting according to the target cooling exchanger return temperature and adjusts the cooling water value setting according to the determined target setting.

10. The method of claim 9, wherein the nonlinear predictive integrating temperature model further models heat balance of the fermentation process, comprising a balance between available cooling and current fermentation heat generation.

11. The method of claim 9, wherein the nonlinear predictive integrating temperature model further models a relationship between cooling water supply temperature and batch fermenter temperature, wherein the nonlinear predictive integrating temperature model is operable to predict the impact of cooling water supply temperature on fermenter temperature;

and wherein the target values comprise a change in a cooling water valve setting to preemptively maintain fermentation batch temperature against disturbances in cooling water supply temperature.

12. The method of claim 9, wherein the nonlinear predictive integrating temperature model further models metabolic activity of yeast in the batch fermentation process as function of one or more of:

ethanol concentration;

sugar concentration;

enzyme concentration;

batch time;

or integrated cooling quantity; and

wherein the target values are determined based at least in part on the modeled metabolic activity of yeast in the batch fermentation process.

13. The method of claim 9, further comprising:

repeating said receiving process information, said executing the nonlinear predictive integrating temperature model, and said controlling in an iterative manner to substantially optimize biofuel production over a fermentation batch.

14. The method of claim 9, wherein the target temperature comprises a target temperature trajectory for the fermentation batch.

15. The method of claim 9, further comprising receiving constraint information specifying one or more constraints for the biofuel production process, wherein said executing the nonlinear predictive integrating temperature model comprises determining the target values subject to the one or more constraints.

16. A system for controlling the temperature of a batch fermenter in a biofuel production process, comprising:

a fermenter,

at least one processor coupled to the fermenter; and

at least one memory medium coupled to the at least one processor, wherein the at least one memory medium stores;

a nonlinear predictive integrating temperature model for a batch fermentation process, wherein the nonlinear predictive integrating temperature model is a function of the volume of the fermentation mash, and

models the dependence of fermenter temperature on fermentation feed temperature when the volume of the fermentation mash is below a designated level, and

models the dependence of fermenter temperature on cooling water valve settings of a cooling exchanger when the volume of the fermentation mash is above the designated level;

program instructions that, when executed by the processor, cause the processor to;

receive an objective for the batch fermentation process specifying a target fermenter temperature for the batch fermentation process,

receive process information for the batch fermentation process, comprising the volume of the fermentation mash and fermenter temperature,

execute the nonlinear predictive integrating temperature model to achieve the objective using the process information as input thereby determining target values a target fermentation feed temperature or a target cooling exchanger return temperature,

adjust the fermentation feed temperature in accordance with the target fermentation feed temperature when the volume of the fermentation mash is below the designated level, and

adjust the cooling exchanger return temperature via a cascaded controller when the volume of the fermentation mash is above the designated level.