Methods of generating energy from cellulosic biofuel waste
View Patent ↗Energy is generated from cellulosic biofuel waste streams, specifically a lignin filter cake and a waste syrup, by combusting these waste products in a fluidized bed combustor under specified conditions. The heat and steam generated can be used to generate electricity and/or in cellulosic biofuel production processes.
1. A method for generating energy from cellulosic biofuel waste, comprising:
feeding a lignin filter cake to a fluidized bed;
feeding a waste syrup to one or more discrete locations in the fluidized bed; and
combusting the lignin filter cake and the waste syrup to generate energy;
wherein the lignin filter cake does not contact the waste syrup.
2. The method of claim 1 , wherein the lignin filter cake has a moisture content of about 35% to about 60%.
3. The method of claim 1 , wherein the waste syrup has a moisture content of about 30% to about 50%.
4. The method of claim 1 , wherein the waste syrup is fed as a stream directed at a plan area of the fluidized bed.
5. The method of claim 4 , wherein the waste syrup is fed as a stream directed at a center of a plan area of the fluidized bed.
6. The method of claim 4 , wherein the plan area is rectangular.
7. The method of claim 1 , wherein the waste syrup is fed to the fluidized bed at a temperature of about 100° F. to about 200° F.
8. The method of claim 1 , wherein the fluidized bed has a bed temperature of about 1200° F. to about 1500° F.
9. The method of claim 1 , wherein flue gas generated by the fluidized bed is recirculated back to the fluidized bed.
10. The method of claim 1 , wherein a furnace wall temperature is kept at about 1000° F. or less.
11. The method of claim 1 , further comprising introducing an additive to the waste syrup to reduce agglomeration.
12. The method of claim 1 , wherein the fluidized bed has a bed drain rate of about 2.5% to about 10%.
13. The method of claim 12 , wherein the fluidized bed drain rate is adjusted based on characteristics of fluctuations in primary zone differential pressure.
14. The method of claim 1 , wherein the lignin filter cake and the waste syrup are fed to the fluidized bed using a dual-phase fuel feeder.
15. The method of claim 14 , wherein the waste syrup is fed below the lignin filter cake.
16. The method of claim 14 , wherein the waste syrup is fed above the lignin filter cake.
17. The method of claim 14 , wherein the waste syrup is fed adjacent to a filter cake feeder, or wherein the waste syrup is fed between filter cake feeders as a separate stream.
18. The method of claim 1 , wherein an alkali species plus phosphorus concentration within the fluidized bed is less than 5% Na+K+P.
19. The method of claim 1 , wherein water in water-cooled walls surrounding the fluidized bed flows in a closed-loop recirculation path.
20. The method of claim 1 , wherein the waste syrup is combusted in the freeboard of the fluidized bed.