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BACKGROUND
The Indian industry is a blend of variety of plants of differentvintage, varied technologies, capacities and efficiencies. The
industry also had continuously undertaken improvement
opportunities wherever possible and increased their productivity.
Some of the plants, which have incorporated all the energy
conservation aspects, have achieved higher efficiencies and are
realising huge benefits.
To replicate these efforts and achieve national level
improvements there is a need to widely disseminate the
information on the major energy potential and conservationprojects implemented by sugar industries. Towards achieving the
above objective, this paper has been prepared.
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SUGAR INDUSTRIES
The sugar industry is one of the ancient and still the largestamongst the food processing industries in the world. Sugar is the
only processing food available in bulk at the highest purity.
India has been the originator of the sugar industry.
At present, India is the second largest producers of sugar. India
has the largest number of modern sugar mills, nearly 600 in
number. The average capacities of the sugar mills are only
2500TCD in India, as against the average capacities of about
10000 TCD in abroad.
With the recent liberalisation of the sugar industry and increasing
demand for sugar and power, the sugar industry is poised for
tremendous growth.
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STEAM & POWER IN SUGAR INDUSTRYSugar industry needs steam and power substantial quantity for
cane crushing and the cane juice processing. The sugar cane has28% to 30% of bagasse and is used for generation of the energy
required, for the operation of the sugar mill.
The bagasse is fired in the boiler, for producing steam at high
pressures, which is extracted through various back-pressureturbines and used in the process. This simultaneous generation
of steam and power commonly referred to as co-generation.
Sugar industries, in general, are operating with low-pressure
steam parameters mainly because of the restriction in usage ofelectrical energy for their captive use only. The steam parameters
have been chosen to match with the process steam requirement
and electrical power requirement for captive use. The surplus
bagasse generated, was sold to the outside market. The energy
content of bagasse is much more than the internal requirement of
the plant.
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SELECTION OF STEAM GENERATORS
&POWER GENERATORS
While selecting Boilers and Steam turbine, the steam parameters
and operating conditions play an important role. Depending upon
the level of technology adopted, various capacities of mills can
produce surplus power, shown in the following Charts.
With larger mill capacities and high-pressure steam the surplus
power increases more than proportional. This huge potential canbe further increased, if the steam & power consumption in the
different sections of the plant can be minimised through high-
pressure steam system in sugar process.
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Assumptions
Bagasse % cane = 27.5 %
Steam : Fuel ratio = 2.21
Steam % cane = 40%
Cane TCD Steam TCH 14 22 32 42 65 85 105
2500 63.02 3.50 4.31 7.71 9.88 11.00 11.86 12.56
3000 75.63 4.20 5.17 9.25 11.86 13.19 14.23 15.07
3500 88.23 4.90 6.03 10.79 13.83 15.39 16.60 17.58
4000 100.83 5.60 6.89 12.33 15.81 17.59 18.97 20.09
4500 113.44 6.30 7.75 13.88 17.79 19.79 21.34 22.60
5000 126.04 7.00 8.61 15.42 19.76 21.99 23.71 25.12
7500 189.06 10.50 12.92 23.13 29.64 32.99 35.57 37.67
10000 252.08 14.00 17.22 30.83 39.53 43.98 47.42 50.23
Power generation in MW at various Steam pressure in Ata
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Specific Steam Consum ption Vs Steam Pre ss ure
0
2
4
6
8
10
12
14
16
18
20
14 22 32 42 65 85 105
Steam Pres sure [Ata]
Sp.
SteamC
onsump
[kg/kW]
`
14 22 32 42 65 85 105
Sp.steam consumption 18 15 8 6 6 5 5
Steam Pressure in Ata
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POTENTIAL FOR SURPLUS POWER
Using high pressure steam and temperature Using extraction cum condensing turbine Elimination of PRDS for steam bleeding Elimination of steam leakages
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POWER CONSUMPTION PER MT OF CANE[From 44 units to 32 units]
(Sugar & Cogen)
Fully automated plant
Change to electrical drive in mills
Variable frequency drive Change chain conveyor to belt conveyor Planetary gear box Energy conservation measures Maximise Cane crushing rate
Using Energy Efficient Motors
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14 22 32 42 65 85 105
34 41 74 95 106 114 121Kw per Tonne of Cane
Steam Pressure in Ata
kW per Tonne of Cane Vs Steam Pressure
0
20
40
60
80
100
120
140
14 22 32 42 65 85 105
Steam Pressure [Ata]
kW
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kW per MT of Bagasse Vs Steam Pressure
0
50
100
150
200
250
300
350
400
450
500
14 22 32 42 65 85 105
Steam Pressure [Ata]
kW
14 22 32 42 65 85 105
122 150 269 345 384 414 438Kw per MT of Bagasse
Steam Pressure in Ata
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POTENTIAL FOR INCREASE
IN
STEAM GENERATION PER MT OF CANE / BAGASSE
High fibre cane Reduce bagasse moisture Using HP heater, Economiser and Air pre heater Increase combustion efficiency High efficiency boiler Recycle the unburnt fuel Automation combustion control Using flash steam recovery from Exhaust condensate Heating the boiler make up water (DM water) using the waste
high temperature secondary condensate.
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REDUCTION OF STEAM CONSUMPTION
PER MT OF CANE[From 52% to 40% on Cane]
Fully automated plant Cane to sugar Optimum [imbibition] addition of water in mills
Continuous pans for sugar boiling Spray pond for cooling system Efficient Steam bleeding system for juice and sugar boiling Flash steam recovery from vapour condensate
Elimination of 9 ata steam for sulphur melting, sugar
washing and sugar drying
Using plate type heat exchanger for juice heating
Application of Thermocompressor system
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BENEFITS OF ENERGY SAVINGS
The major benefits of energy saving in sugar industry can be
broadly classified as
Bagasse can be saved, which can be directly sold in themarket.
Passing the surplus steam through an extraction cumcondensing turbine, provided a commercial cogeneration
system is available, can generate additional power
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SUMMARY
In the recent years, with the increasing power Demand supply
-gap the generation of power from the excess bagasse has been
found to be attractive. This also offers an excellent opportunity
for the sugar mills to generate additional revenue for the mills.
This also contributes to serve the national cause in a small way
by bridging the Demand supply gap.