energy conservation in power and steam consumption

7/30/2019 Energy Conservation in Power and Steam Consumption

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Energy Conservation in Powerand Steam Consumption.


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There is hardly any need to explain theimportance of the subject which has not onlycommercial, but environmental implicationsalso.

Indian sugar mills are operating on 18- 20KWH power consumption per TCH in caseswhere fiberiser & mills are having steamTurbines. This figure is 26-28 KWH in caseswhere fiberiser and Mills are having motors.This figure is higher in most of the PakistanMills.


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Similarly steam consumption is 33-38% and

our next target is 30 %. If you add 6-7 %

extra consumption due to refined sugar, thenormal figures of steam % cane in Pakistan

is much higher. If you take figure of

Bagasses consumption % cane, then IndianMills are further ahead, because of better

figure of steam fuel ratio of 2.3 plus.

Above goes to show, that there is a

significant scope of improvement in Pak

Sugar Mills.


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We first take up, Techniques to

reduce Power consumption.

1. Cane Preparation whole cane fiberizer canbe used in 5 and 6 Mill tandems technicallythere is no justification in adopting shredder insuch tandems because basic requirement ofshredder is much higher PI requiring higherpower consumption for cane preparationbefore shredder.

2. Use of slip Resistance at levelers & cutter SRMotors Approx 20 % slip will reduce powerby 10%.

3. Use of Induction Generator at ND end ofFiberizer Turbine.


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4. Use of Planetary Gear Box instead of helicaland worm reducers.

5. Use of Auto recirculation valves in Boiler feedPump.

6. Use of High Efficiency Motors having cold

rolled stampings and also use of correct sizemotors.

7. Use of MF pumps with proper head in place orCF pumps at injection and spray with properhead.

8. Use of High flow Pumps (i.e. Screw pump withRubber stator) Pumps I.P.O. Star or gear

pump for Molasses.


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9. Use of Backward bend design or I D of FD fanimpeller.

10. Use of water multijet system IPO Vacuumpumps, at vacuum filter station.

11. Use of proper condensate flashing systemusing only two pumps for entire evaporatorstation.

12. Use of Least possible H.S. of last bodyevaporator with VLJH.

13. Use of Translucent sheets on roof and photosensing switches for street light.


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14. Use of any spare alternator as P.F. improvementdevice.

15. Use of Belt conveyors IPO drag conveyorsWedge belts IPO ordinary V-Belts & plastic wearbushes IPO Metallic ones.

16. Use of Bigger size vacuum filters.

17. Avoiding use of Pan Circulator by using ventjigger Technology.

18. Conventional methods like continuous pan, HVfor Transmission of Electric Power Millautomation single entry highly efficient SEDCondensers and VFDs are already being used by

so many Pak mills. Hence I am simply mentioningthem and not elaborating.


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Conclusion

There is a definite potential of reduction in

Power consumption by 10-20%. But decision to

adopt any method has to be based on cost-

benefit analysis which will be different fordifferent Mills. But if you are going for exporting

Power to any other Industrial establishment,

each one of these is cost effective. However

final decision will depend on local conditions forpriorities etc.


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Now I come to Techniques for

reduction in steam consumption.

1. Extensive and Effective vapor Bleedingsystems

55 C plus temp of with last body evaporator

and approx 75 C temp of last but one body caneasily be achieved for Raw Juice.

Similarly for Secondary Juice 90 C plus temp

with second body and 103 C plus temp with 1stbody vapors is practicable with 1st body vapors.Clear juice should be 1st heated by 1st body vapor& then by exhaust before feeding to evaporator.


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A, B & R Pans can be boiled with 2nd body

vapors. C-Pan can also be boiled with 2 vapors if it

is continuous Pan, otherwise 1st body vaporsshould be used. Now third body of Quintuple is

being used for A& R Pans.

Above system along with effective Condensate

Flash system will definitely bring down steam

consumption by more than 5-6 % in most of PakMills. But this needs an intelligent distribution of

H.S. at evaporator and minor modification in pans.


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2. Adoption of Waste Heat RecoverySystem at

a) Clarifier flash.

b) Flash heat from exhaust condensates or

Pressuring the Boiler Feed Water Tank.

c) Heat of waste condensates, drains &vents.

d) Flue gas heat to heat feed water to avoiduse of exhaust at Deareator.


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e) Flue gas heat to heat condensate to be used in

remelter CF wash Water.

f) NCG and /or low grade vapors heat to be used

for molasses heating.

g) Use of spare Juice Heater as circulate.

h) Use of low pressure vapors or exhaust for panwashing IPO 4kg steam.


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i) Use of Vibro Screens to avoid heat loss at CJscreening. These Vibro screens at limestation will also reduce scale formation at

evaporator.j) Adoption of Quint or six effect evaporator by

use of falling film / Rising film evaporator.

k) Use of 1st body vapors for BC massecuite

reheating.l) Some of following steps (which may appear

to be out of context of paper) will definitelyhelp.

1. Low cost Bagasse Drier

2. Re feeding of fly ash

3. Use of blow down heat

4. Bringing Down flue gas temperature toapprox 125 C.


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Important Note and word of Caution.

While adopting above measures one mustmatch the exhaust production with consumption. Ifconsumption is lass than production then followingmeasure may be considered.

i. Increasing Live steam temp & pressure up toallowable limits.

ii. Increasing No. of stages in steam Turbines.

iii. Modification in design of Nozzles and blades


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As stated earlier, all these steps will

defiantly bring down steam consumption by

more than 6%. You can easily save

additional 3 lack Mands bagasse on the

crush figure of 2 Crore Mands. This speaks

of viability of any of the system given above.

At the end, I am highly thankful to all PSST

authorities for having given me chance topresent this paper.

energy conservation in power and steam consumption

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