Sweet Savings

Sugar mills adopt energy efficient practices to achieve cost optimization

Sugar manufacturers that are grappling with issues such as declining sugarcane production, rising raw material costs, increasing energy cost and stringent emission norms can undertake energy conservation measures to achieve cost optimisation. Energy consumption at a sugar manufacturing facility is mainly on account of process heating and running various turbo drives. The sugar industry has a unique advantage of utilising bagasse, a by-product of the sugar manufacturing process, as a fuel to produce electricity and steam by cogeneration.

However, the amount of bagasse produced may vary from unit to unit, and many units depend on grid-connected electricity as well as fuels such as diesel and coal to meet their power requirements. The sugar industry has significant scope for improvement in energy efficiency, which can reduce both energy consumption and associated energy costs. Realising the benefits of energy efficiency, sugar mills across the country have adopted energy efficient practices. Power Line takes a look at some of the energy efficiency initiatives taken by leading sugar manufacturers in the country…

EID Parry (India) Limited, Nellikuppam, Tamil Nadu

EID Parry (India) Limited is one of the flagship companies of the Murugappa Group with presence in sugar and related value-added products. The company’s Nellikuppam integrated sugar plant in Cuddalore, Tamil Nadu, has taken significant strides in energy conservation. The plant has a cane crushing capacity of 7,500 tonnes per day (tpd), a sugar refining capacity of 170 tpd, a distillation capacity of 750 kilolitres per day and a cogeneration capacity of 24.5 MW. The sugar unit implemented several energy conservation initiatives during 2016-17, which led to annual energy savings of Rs 62 million. As a result of these measures, the unit’s steam consumption per tonne of cane declined from 32.81 per cent in 2015-16 to 32.6 per cent in 2016-17. During the same period, the unit’s electrical energy consumption declined from 24.74 kWh per tonne of cane to 24.51 kWh per tonne of cane.

To this end, some of the key energy conservation initiatives taken by the company in 2016-17 were modification of the standard operating procedure for syrup brix improvement, replacement of electric strip heating systems with hot water coil systems, and waste heat recovery from sugar second body condensate. Other energy saving methods such as the utilisation of biogas from the biodigester and direct pumping of sugar condensate to the deaerator instead of the feedwater storage tank also yielded impressive results.

The maximum savings of around Rs 21 million were realised through improvement in the evaporator syrup. The company, through the kaizen approach, found that the steam consumption in evaporators was quite high owing to low syrup concentration and scaling in the evaporator tubes. It took steps to clear the calcium sulphate salts that caused scaling and replaced the butterfly valve with a globe valve to ensure uniform syrup distribution. As a result, the evaporator outlet syrup concentration increased by 11 per cent and steam consumption per tonne of cane crushed dropped from 35.2 per cent to 32.6 per cent.

The increase in steam generation from the biogas boiler also led to considerable savings of around Rs 10.5 million annually. This was achieved by  increasing the size of the burner nozzle and installing an air preheater. These modifications helped in increasing the steam generation from 10 tonnes per hour (tph) to 12 tph.

Dalmia Chini Mills, Nigohi, Uttar Pradesh

Dalmia Bharat Sugar and Industries Limited is one of the leading sugar producers in the country with a total cane crushing capacity of 22,500 tpd. The company’s Nigohi plant at Shahjahanpur in Uttar Pradesh is a pioneer in energy conservation in the sugar industry.

The plant was set up during 2006-07 with a crushing capacity of 7,500 tpd and a cogeneration capacity of 27 MW. The cogeneration power project is registered under the clean development mechanism.

The Nigohi plant has been continuously working on its energy conservation strategies. As a result, the plant’s electrical energy consumption per tonne of sugar reduced by 11.16 per cent from 324.5 kWh in 2014-15 to 288.3 kWh in 2015-16. Similarly, its thermal energy consumption per tonne of sugar declined by 11.78 per cent from 6.01 mkCal to 5.3 mkCal.

The key energy conservation initiatives taken by the company include the installation of distributed control systems and use of variable frequency drives (VFDs) on pumps/fans. In addition, it replaced the 250 W incandescent lamps in the facility with LED lights and modified the design of the mill cane carrier by reducing the feeding depth. Further, it increased the rotations per minute of the cane chopper, which reduced power consumption in cane cutters and shredder motors. The company also reduced the auxiliary consumption of the power plant at the sugar unit by optimising its energy saving equipment and reducing power consumption by maintaining the average crush. In addition, the plant is following a dedicated energy and environment policy. It is committed to improving its environmental, energy, occupational health and safety performance.

Conclusion

There is immense scope for reducing energy consumption and improving energy efficiency in the sugar industry, thereby providing manufacturers a competitive edge with substantial monetary savings. Simple measures such as the installation of VFDs, replacement of conventional systems with more efficient ones and design modifications in certain equipment can lead tosignificant energy savings. These initiatives have a short payback period and thus the results are quickly reflected in the company’s profitability. Besides, steps to improve the operational efficiency of cogeneration plants installed at sugar units can drive electricity generation and reduce the manufacturers’ dependence on expensive grid electricity. Net, net, energy conservation initiatives can go a long way in securing the energy needs of sugar industries.

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