Transcript Energy Self-Sufficiency and Cogeneration in Louisiana Cane

ENERGY SELF-SUFFICIENCY AND
COGENERATION IN LOUISIANA
CANE SUGAR FACTORIES
Harold Birkett and Jeanie Stein
Audubon Sugar Institute
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
GAS COST ($) / MCF
14
12
$ / MCF
10
8
6
4
2
0
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
CROP YEAR
GAS / TON CANE
1.25
GAS, MCF
1.00
0.75
0.50
Hurricane Lili
Tropical Storm Isidore
0.25
0.00
1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
CROP YEAR
ELECTRICITY COST
12
CENTS / KWH
.
11
10
9
8
7
6
5
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
CROP YEAR
TRUE FIBER % CANE
13.0
FIBER, %
12.5
12.0
11.5
11.0
10.5
10.0
1998
1999
2000
2002
2003
2004
CROP YEAR
CANE FIBER
1998-2006 AVG = 11.85; 2006 = 12.39
AVERAGE
2005
2006
TRUE FIBER % PREPARED CANE
16
14
FIBER, %
12
10
8
6
4
2
0
1
3
5
7
9 11 13 15 17 19 21 23 25 27 29 31 33 35
SAMPLE
PREP CANE
2005 & 2006 CROPS; AVG = 11.88
AVERAGE
TRUE FIBER % BAGASSE
45
FIBER, %
.
40
35
30
25
20
15
10
5
0
1
3
5
7
9
11 13
15
17 19
21 23
MILL TEST
FIBER, %
2005 & 2006 CROPS; AVG = 38.08
AVERAGE
25 27
29 31
33
DRY FIBER (BAGACILLO)
% MIXED JUICE
1.0
DRY FIBER, %
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
2
3
4
5
6
7
8
9
10 11 12 13
SAMPLE
DRY FIBER
AVERAGE
2005 CROP; AVG = 0.39
14 15 16 17
BAGASSE % CANE
BAGASSE % CANE
42
40
38
36
34
32
30
28
26
24
22
20
1
3
5
BAG % CANE
7
9
11 13
LESS 1% F%C
15 17 19
MILL TEST
AVERAGE
2005 & 2006 MILL TEST DATA; AVG = 31.41 VS 28.77
21 23
25 27
29 31 33
AVERAGE (WITH 1% LESS F%C)
BAGASSE % CANE
BAGASSE % CANE
.
34
33
32
31
30
29
1986 1988
1990 1992 1994
1996 1998 2000 2002
CROP YEAR
BAGASSE % CANE
FACTORY REPORTED DATA; AVG = 31.8
AVERAGE
2004 2006
MOISTURE % BAGASSE
MOISTURE, % .
62
60
58
56
54
52
50
48
5
15
25
35
45
55
65
SAMPLE
BAGASSE MOISTURE
2005 & 2006 CROP (MILLING & BOILER SAMPLES); AVG = 53.86
AVERAGE
75
ASH % BAGASSE
14
12
ASH, %
10
8
6
4
2
0
5
10
15
20
25
30
35
40
45
50
55
60
SAMPLE
BAGASSE
AVERAGE
2005 & 2006 CROPS (MILLING & BOILER SAMPLES); AVG = 5.19
65
70
75
80
ASH % BAGASSE
14
.
10
ASH, %
12
8
6
4
2
0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
YEAR
AVERAGE
HIGH
LOW
PRIMARY FACTORS AFFECTING
BOILER EFFICIENCY
1. The quality of the fuel (bagasse).
2. The quantity of excess air used for
combustion.
3. The temperature of the flue gases.
4. The completeness of the combustion.
OXYGEN % FLUE GAS
20
OXYGEN, %
.
18
16
14
12
10
8
6
4
2
0
BOILER TEST
OXYGEN
2005 & 2006 CROPS; AVG = 7.99
AVERAGE
BOILER EXCESS AIR
EXCESS AIR, % .
500
400
300
200
100
0
BOILER TEST
EXCESS AIR
2005 & 2006 CROPS; AVG = 72.8
AVERAGE
FLUE GAS TEMPERATURE
FLUE GAS TEMP, F
700
600
500
400
300
BOILER TEST
FLUE GAS TEMP
2005 & 2006 CROPS; AVG = 450
AVERAGE
PREHEATED AIR TEMP, F
.
PREHEATED AIR TEMPERATURE
700
600
500
400
300
BOILER TEST
PREHEATED AIR TEMP
2005 & 2006 CROPS; AVG = 457 F
AVERAGE
BOILER EFFICIENCY
EFFICIENCY, % .
70
60
50
40
30
BOILER TEST
EFFICIENCY
2005 & 2006 CROPS; AVG = 55.45
AVERAGE
POUNDS STEAM PRODUCED
PER POUND BAGASSE BURNED
LBS STEAM/ LB BAG .
3
2
1
0
BOILER TEST
LBS STEAM / LB BAG
2005 & 2006 CROPS; AVG = 1.89
AVERAGE
METHODS TO IMPROVE
BOILER EFFICIENCY
1. Improve the bagasse quality (lower
moisture & ash).
2. Reduce the level of excess air.
3. Reduce the temperature of the flue
gases.
EFFECTIVE MOISTURE
MOISTURE =
53.99
MOISTURE = 53.99 %
FIBER+S.S.=
41.15
ASH = 4.86
TOTAL = 100.00
EFFECTIVE
MOISTURE =
56.75 %
EFFECTIVE BAGASSE MOISTURE
VS BOILER EFFICIENCY
EFFICIENCY, % .
65
60
55
50
45
40
50
52
54
56
58
60
62
EFFECTIVE MOISTURE, %
2005 & 2006; r=0.58; Effective Moisture = Moisture % Ash-Free Bagasse
64
66
EFFECT ON BOILER EFFICIENCY
DECREASE
INCREASE
MOISTURE %
EFFICIENCY BY
BAGASSE BY 1%
0.8%
ASH % BAGASSE
EFFICIENCY BY
BY 1%
0.5%
BOILER EFFICIENCY VS
FLUE GAS TEMPERATURE
EFFICIENCY, % .
70
65
60
55
62
60
56
50
45
40
250
350
450
550
FLUE GAS TEMPERATURE, F
USING AVG INPUTS, VARYING FLUE GAS TEMP ONLY
650
750
BASIC ASSUMPTIONS:
• Grinding rate, tcd
10,000
• Cane, % pol
% fiber (true)
13.0
11.24
• Bagasse, % moisture
% ash
54.0
3.00
• Imbibition % cane
30.0
• Syrup purity
85.0
BASIC ASSUMPTIONS:
•
•
•
•
•
•
•
Boiler efficiency,%
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
• Exhaust steam
55.0
250.0
25.0
9.6
50.0
68.0
20,000
10,000
CASE 1
TYPICAL LOUISIANA FACTORY
10,000 TCD
BAGASSE FROM MILL = 238,043 LB/HR
221,594 LB/HR BAGASSE
BOILERS
STEAM
210 PSIG
392°F
EXCESS BAGASSE
= 16,449 LB/HR
= 6.9 %
447,620 LB/HR
FACTORY
TURBINES
(10,417 HP)
BACK PRESS
T-G
(870 KW)
395,088 LB/HR
32,512 LB/HR
15,859 LB/HR
CONDENSATE
350,796 LB/HR
EVAPORATOR
QUAD, V1 FOR
JUICE HEATERS
& HIGH GRADE PANS
MAKE-UP
TO EXHAUST
20,000 LB/HR
0 LB/HR
26,752 LB/HR
LOW GRADE
PANS
MISCELLANEOUS
24,193 LB/HR
BFW
DEAERATOR
10,000 LB/HR
MISCELLANEOUS
BUY 3,130 KW
CASE 2
HIGH PRESSURE STEAM & QUINTUPLE EFFECT EVAPORATOR
10,000 TCD
BAGASSE FROM MILL = 238,043 LB/HR
201,231 LB/HR BAGASSE
BOILERS
STEAM
650 PSIG
750°F
EXCESS BAGASSE
= 36,812 LB/HR
= 15.5 %
344,105 LB/HR
DESUPERHEATING
WATER
20,697 LB/HR
FACTORY
TURBINES
(10,417 HP)
BACK PRESS
T-G
(6,392 KW)
201,984 LB/HR
122,121 LB/HR
315,141 LB/HR
EVAPORATOR
QUINTUPLE
V1 TO ALL PANS & 3RD LJH
V2 TO 2ND LJH, V3 TO 1ST LJH
0 LB/HR
LOW GRADE
PANS
MAKE-UP
TO EXHAUST
MISCELLANEOUS
20,000 LB/HR
0 LB/HR
19,661 LB/HR
BFW
DEAERATOR
10,000 LB/HR
MISCELLANEOUS
SURPLUS 2,392 KW
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
STEAM
650 PSIG
750°F
BOILERS
TOPPING TURBINE
210 PSIG/570°F
DESUPERHEATING
WATER
18,730 LB/HR
7,277 KW
346,079 LB/HR
FACTORY
TURBINES
(10,417 HP)
BACK PRESS
T-G
(221 KW)
319,402 LB/HR
6,676 LB/HR
315,141 LB/HR
EVAPORATOR
EXCESS BAGASSE
= 35,658 LB/HR
= 15.0 %
0 LB/HR
LOW GRADE
PANS
QUINTUPLE
V1 TO ALL PANS & 3RD LJH
V2 TO 2ND LJH, V3 TO 1ST LJH
MAKE-UP
TO EXHAUST
MISCELLANEOUS
20,000 LB/HR
0 LB/HR
19,667 LB/HR
BFW
DEAERATOR
10,000 LB/HR
MISCELLANEOUS
SURPLUS 3,498 KW
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.
ACKNOWLEDGMENTS
AMERICAN SUGAR CANE LEAGUE
ALL LOUISIANA SUGAR MILLS
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
53.86
5.19
7.99
450
457
707
150
• PRACTICAL DEGREE OF COOLING OF FLUE GASES
Boiler Outlet Gas Temperature, F
Minimum Practical Flue Gas Temperature, F
Degree of Cooling of Flue Gases, F
= 707
= 250
457
• POTENTIAL COOLING OF FLUE GASES BY VARIOUS
METHODS, F
Theoretical
Actual
Using Air Preheaters
Economizers
Bagasse Dryers
438
150
427
• RELATIVE WEIGHTS OF BOILER FLOWS
Bagasse
BF Water
Air
Flue Gas
= 1.00
= 2.10
= 3.92
= 4.87
257
150
?
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:
1. Complex – multiple conveyors, rotating
equipment, and cyclones.
2. High horsepower requirements – especially for fan
on cyclone.
3. Dry bagasse is a fire hazard.
4. Higher furnace temperature may improve
combustion but may also cause the ash to melt.
5. Increased pollution (particulate carryover).
BOILER EFFICIENCY VS
FLUE GAS TEMPERATURE
70
Practical final flue gas temp = 250 F
(requires air preheaters + economizers)
64.84
EFFICIENCY, %
65
60
56.76
55
50
Current operation with a/h = 450 F
(using only air preheaters)
45
40
200
250
300
350
400
450
46.02
No waste heat recovery,
flue gas = 707 F
500
550
FLUE GAS TEMP, F
EFFICIENCY, %
600
650
700
750
PREPARATION INDEX
and
MILLING
PREPARATION INDEX VS
TANDEM POL EXTRACTION
POL EXTRACTION, % .
100
95
90
85
80
65
70
75
80
PREPARATION INDEX
TANDEM EXT
2005 DATA, r = 0.49
85
90
PREPARATION INDEX VS
TANDEM POL EXTRACTION
POL EXTRACTION, % .
100
95
90
85
80
65
70
75
80
PREPARATION INDEX
TANDEM EXT
2006 DATA, r = 0.23
85
90
PREPARATION INDEX VS
FIRST MILL POL EXTRACTION
POL EXTRACTION, % .
80
75
70
65
60
55
50
45
40
65
70
75
80
PREPARATION INDEX
TANDEM EXT
2005 DATA, r = 0.73
85
90
PREPARATION INDEX VS
FIRST MILL POL EXTRACTION
POL EXTRACTION, % .
80
75
70
65
60
55
50
45
40
65
70
75
80
PREPARATION INDEX
TANDEM EXT
2006 DATA, r = 0.18
85
90
TANDEM EXTRACTION, %
.
FIRST MILL POL EXTRACTION VS
TANDEM POL EXTRACTION
100
95
90
85
80
40
45
50
55
60
65
FIRST MILL EXTRACTION, %
POL EXT
2005 DATA, r = 0.66
70
75
TANDEM EXTRACTION, % .
FIRST MILL POL EXTRACTION VS
TANDEM POL EXTRACTION
100
95
90
85
80
40
45
50
55
60
65
FIRST MILL EXTRACTION, %
POL EXT
2006 DATA, r = 0.83
70
75
TANDEM EXTRACTION, % .
FIRST MILL EXTRACTION VS
TANDEM (5 MILLS) EXTRACTION
100
95
90
85
80
40
45
50
55
60
65
FIRST MILL EXTRACTION, %
POL EXT
2005 DATA, r = 0.92
70
75
TANDEM EXTRACTION, % .
FIRST MILL EXTRACTION VS
TANDEM (5 MILLS) EXTRACTION
100
95
90
85
80
40
45
50
55
60
65
FIRST MILL EXTRACTION, %
POL EXT
2006 DATA, r = 0.98
70
75
TANDEM EXTRACTION, % .
FIRST MILL EXTRACTION VS
TANDEM (6 MILLS) EXTRACTION
100
95
90
85
80
40
45
50
55
60
65
FIRST MILL EXTRACTION, %
POL EXT
2005 DATA, r = 0.53
70
75
TANDEM EXTRACTION, %
.
FIRST MILL EXTRACTION VS
TANDEM (6 MILLS) EXTRACTION
100
95
90
85
80
40
45
50
55
60
FIRST MILL EXTRACTION, %
POL EXT
2006 DATA, r = 0.89
65
70
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
TANDEM EXTRACTION, %
.
PREPARATION INDEX VS INDIVIDUAL
FACTORY TANDEM EXTRACTION
100
95
90
85
80
70
72
74
76
78
80
PREP INDEX
POL EXT
82
84
86
88
ACKNOWLEDGMENTS
AMERICAN SUGAR CANE LEAGUE
ALL LOUISIANA SUGAR MILLS
TRUE FIBER % BAGASSE
45
40
FIBER, %
35
30
25
20
15
10
5
0
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
YEAR
FIBER, %
AVG = 37.04
AVERAGE