1. Harold Birkett and Jeanie Stein Audubon Sugar Institute
ENERGY SELF-SUFFICIENCY AND COGENERATION IN LOUISIANA CANE SUGAR FACTORIES
Harold Birkett and Jeanie Stein
Audubon Sugar Institute

2. BOILERS & COGENERATION
OBJECTIVES
To present actual data on bagasse availability and analysis
To present data on boiler efficiencies and suggestions for improving them
To discuss factory modifications to reduce steam usage and increase electricity cogeneration

3. GAS COST ($) / MCF

4. GAS / TON CANE
Hurricane Lili
Tropical Storm Isidore

5. ELECTRICITY COST

6. TRUE FIBER % CANE
AVG = 11.85; = 12.39

7. TRUE FIBER % PREPARED CANE
2005 & 2006 CROPS; AVG = 11.88

8. TRUE FIBER % BAGASSE
2005 & 2006 CROPS; AVG = 38.08

9. DRY FIBER (BAGACILLO) % MIXED JUICE
2005 CROP; AVG = 0.39

10. BAGASSE % CANE
2005 & MILL TEST DATA; AVG = VS

11. BAGASSE % CANE
FACTORY REPORTED DATA; AVG = 31.8

12. MOISTURE % BAGASSE
2005 & CROP (MILLING & BOILER SAMPLES); AVG = 53.86

13. ASH % BAGASSE
2005 & 2006 CROPS (MILLING & BOILER SAMPLES); AVG = 5.19

14. ASH % BAGASSE

15. PRIMARY FACTORS AFFECTING BOILER EFFICIENCY
The quality of the fuel (bagasse).
The quantity of excess air used for combustion.
The temperature of the flue gases.
The completeness of the combustion.

16. OXYGEN % FLUE GAS
2005 & 2006 CROPS; AVG = 7.99

17. BOILER EXCESS AIR
2005 & 2006 CROPS; AVG = 72.8

18. FLUE GAS TEMPERATURE
2005 & 2006 CROPS; AVG = 450

19. PREHEATED AIR TEMPERATURE
2005 & 2006 CROPS; AVG = 457 F

20. BOILER EFFICIENCY
2005 & 2006 CROPS; AVG = 55.45

21. POUNDS STEAM PRODUCED PER POUND BAGASSE BURNED
2005 & 2006 CROPS; AVG = 1.89

22. METHODS TO IMPROVE BOILER EFFICIENCY
Improve the bagasse quality (lower moisture & ash).
Reduce the level of excess air.
Reduce the temperature of the flue gases.

23. EFFECTIVE MOISTURE EFFECTIVE MOISTURE = 56.75 % MOISTURE = 53.99 %
FIBER+S.S.= 41.15
ASH = 4.86
TOTAL =

24. EFFECTIVE BAGASSE MOISTURE VS BOILER EFFICIENCY
2005 & 2006; r=0.58; Effective Moisture = Moisture % Ash-Free Bagasse

25. EFFECT ON BOILER EFFICIENCY
DECREASE
INCREASE
MOISTURE % BAGASSE BY 1%
EFFICIENCY BY %
ASH % BAGASSE
BY 1%
EFFICIENCY BY
0.5%

26. BOILER EFFICIENCY VS FLUE GAS TEMPERATURE62 60 56
USING AVG INPUTS, VARYING FLUE GAS TEMP ONLY

27. BASIC ASSUMPTIONS: Grinding rate, tcd 10,000 Cane, % pol 13.0
% fiber (true)
Bagasse, % moisture
% ash
Imbibition % cane
Syrup purity

28. BASIC ASSUMPTIONS: Boiler efficiency,% 55.0
Boiler feed water temp, F
Power required, hp/tch
Electricity required, kw/tch
Turbine efficiency, %
Turbo-generator efficiency, %
Misc. steam usage, lb/hr
Live steam ,000
Exhaust steam ,000

29. CASE 1 TYPICAL LOUISIANA FACTORY 10,000 TCD
BAGASSE FROM MILL = 238,043 LB/HR
221,594 LB/HR BAGASSE
EXCESS BAGASSE
= 16,449 LB/HR
= 6.9 %
BOILERS
STEAM
210 PSIG
392°F
447,620 LB/HR
FACTORY
TURBINES
(10,417 HP)
BACK PRESS
T-G
(870 KW)
MAKE-UP
TO EXHAUST
MISCELLANEOUS
20,000 LB/HR
395,088 LB/HR
32,512 LB/HR
0 LB/HR
15,859 LB/HR
350,796 LB/HR
26,752 LB/HR
24,193 LB/HR
10,000 LB/HR
CONDENSATE
EVAPORATOR
LOW GRADE PANS
BFW
DEAERATOR
MISCELLANEOUS
QUAD, V1 FOR
JUICE HEATERS
& HIGH GRADE PANS
BUY 3,130 KW

30. CASE 2 HIGH PRESSURE STEAM & QUINTUPLE EFFECT EVAPORATOR 10,000 TCD
BAGASSE FROM MILL = 238,043 LB/HR
201,231 LB/HR BAGASSE
EXCESS BAGASSE
= 36,812 LB/HR
= %
BOILERS
STEAM
650 PSIG
750°F
344,105 LB/HR
FACTORY
TURBINES
(10,417 HP)
BACK PRESS
T-G
(6,392 KW)
MAKE-UP
TO EXHAUST
MISCELLANEOUS
DESUPER-
HEATING
WATER
20,697 LB/HR
20,000 LB/HR
201,984 LB/HR
122,121 LB/HR
0 LB/HR
315,141 LB/HR
0 LB/HR
19,661 LB/HR
10,000 LB/HR
EVAPORATOR
LOW GRADE PANS
BFW
DEAERATOR
MISCELLANEOUS
QUINTUPLE
V1 TO ALL PANS & 3RD LJH
V2 TO 2ND LJH, V3 TO 1ST LJH
SURPLUS 2,392 KW

31. CASE 3 HIGH PRESSURE STEAM, TOPPING TURBINE & QUINTUPLE EFFECT EVAPORATOR 10,000 TCD
BAGASSE FROM MILL = 238,043 LB/HR
202,385 LB/HR BAGASSE
EXCESS BAGASSE
= 35,658 LB/HR
= %
BOILERS
STEAM
650 PSIG
750°F
TOPPING TURBINE
7,277 KW
210 PSIG/570°F
346,079 LB/HR
FACTORY
TURBINES
(10,417 HP)
BACK PRESS
T-G
(221 KW)
MAKE-UP
TO EXHAUST
MISCELLANEOUS
DESUPER-
HEATING
WATER
18,730 LB/HR
20,000 LB/HR
319,402 LB/HR
6,676 LB/HR
0 LB/HR
315,141 LB/HR
0 LB/HR
19,667 LB/HR
10,000 LB/HR
EVAPORATOR
LOW GRADE PANS
BFW
DEAERATOR
MISCELLANEOUS
QUINTUPLE
V1 TO ALL PANS & 3RD LJH
V2 TO 2ND LJH, V3 TO 1ST LJH
SURPLUS 3,498 KW

32. SUMMARY
Improving quality of bagasse (lower moisture and lower ash) can improve boiler efficiency and increase steam production.
Boiler efficiency can be improved (in La. primary area of improvement can be through installation of economizers to reduce high average flue gas temperature).
Even without improvements in bagasse quality or boiler efficiency, use of high pressure steam and more efficient evaporator schemes can make La. factories energy independent or exporters of electricity.

33. ACKNOWLEDGMENTS
AMERICAN SUGAR CANE LEAGUE
ALL LOUISIANA SUGAR MILLS

35. BOILER WASTE HEAT RECOVERY
ASSUMPTIONS (State Average for 2005 & 2006)
Moisture % Bagasse
Ash % Bagasse
Oxygen % Flue Gases
Flue Gas Temperature, F
Preheated Air Temperature, F
Boiler Outlet Gas Temperature, F
Flue Gas Dew Point, F

36. PRACTICAL DEGREE OF COOLING OF FLUE GASES
Boiler Outlet Gas Temperature, F = 707
Minimum Practical Flue Gas Temperature, F = 250
Degree of Cooling of Flue Gases, F
POTENTIAL COOLING OF FLUE GASES BY VARIOUS METHODS, F Theoretical Actual
Using Air Preheaters
Economizers
Bagasse Dryers ?
RELATIVE WEIGHTS OF BOILER FLOWS
Bagasse = 1.00
BF Water = 2.10
Air = 3.92
Flue Gas = 4.87

37. Air preheaters and economizers have no moving parts
and are very dependable. Their use may require fans and
pumps or higher head and horsepower.
Bagasse dryers have the following disadvantages:
Complex – multiple conveyors, rotating equipment, and cyclones.
High horsepower requirements – especially for fan on cyclone.
Dry bagasse is a fire hazard.
Higher furnace temperature may improve combustion but may also cause the ash to melt.
Increased pollution (particulate carryover).

38. BOILER EFFICIENCY VS FLUE GAS TEMPERATURE
Practical final flue gas temp = 250 F
(requires air preheaters + economizers)
64.84
56.76
Current operation with a/h = 450 F
(using only air preheaters)
46.02
No waste heat recovery,
flue gas = 707 F

40. PREPARATION INDEX and MILLING

41. PREPARATION INDEX VS TANDEM POL EXTRACTION
2005 DATA, r = 0.49

42. PREPARATION INDEX VS TANDEM POL EXTRACTION
2006 DATA, r = 0.23

43. PREPARATION INDEX VS FIRST MILL POL EXTRACTION
2005 DATA, r = 0.73

44. PREPARATION INDEX VS FIRST MILL POL EXTRACTION
2006 DATA, r = 0.18

45. FIRST MILL POL EXTRACTION VS TANDEM POL EXTRACTION
2005 DATA, r = 0.66

46. FIRST MILL POL EXTRACTION VS TANDEM POL EXTRACTION
2006 DATA, r = 0.83

47. FIRST MILL EXTRACTION VS TANDEM (5 MILLS) EXTRACTION
2005 DATA, r = 0.92

48. FIRST MILL EXTRACTION VS TANDEM (5 MILLS) EXTRACTION
2006 DATA, r = 0.98

49. FIRST MILL EXTRACTION VS TANDEM (6 MILLS) EXTRACTION
2005 DATA, r = 0.53

50. FIRST MILL EXTRACTION VS TANDEM (6 MILLS) EXTRACTION
2006 DATA, r = 0.89

51. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

52. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

53. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

54. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

55. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

56. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

57. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

58. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

59. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

60. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

61. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

62. PREPARATION INDEX VS INDIVIDUAL FACTORY TANDEM EXTRACTION

63. ACKNOWLEDGMENTS
AMERICAN SUGAR CANE LEAGUE
ALL LOUISIANA SUGAR MILLS

65. TRUE FIBER % BAGASSE
Added here for April seminar booklet
AVG = 37.04