boiler & power

8/14/2019 boiler & power

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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


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



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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.

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