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Energy conservation initiatives in the segment

The chemicals industry is the oldest and one of the most important industries of the country. It includes basic chemicals and their products – petrochemicals, fertilisers, pesticides, paints, varnishes, gases, soaps, perfumes and toiletries, and pharmaceuticals. It is one of the most diversified industries, covering a number of commercial products, and occupies a pivotal position in meeting the basic needs.

The chemicals industry provides the building blocks for several downstream industries such as textiles, paper, paints, varnishes, soaps, detergents and pharmaceuticals. The production of major chemicals and petrochemicals in 2016-17 (up to November 2016) grew by 5.6 per cent to 17.16 million tonnes (mt), compared to 16.25 mt in 2015-16 (up to November 2015). The industry accounts for a significant portion of country’s total energy consumption.

The chemicals and petrochemicals industry is increasingly working towards reducing the energy intensity of its operations, adopting the latest technologies, minimising pollution emissions and increasing the share of recyclable products in its portfolio.

Power Line highlights the energy conservation measures taken by three leading chemicals and petrochemicals units that have been recognised by the Bureau of Energy Efficiency (BEE)…

UPL Limited, Unit 2, Ankleshwar, Gujarat

UPL Limited is a global company dealing in generic chemicals, crop protection and seeds. Headquartered in Mumbai, it was previously known as United Phosphorus Limited.

Unit 2 of the company started operations in 1993 and is spread over 16.2 acres. The manufacturing unit is certified with ISO 9000, ISO 14000 and ISO 18000, and produces acephate, devrinol, phorate, turbophos and other agro and speciality chemicals.

Over the years, the unit has adopted several measures to reduce its energy consumption. These include the heat integration (pinch) methodology, air compressor heat recovery, LED lights, harvesting of solar light through pipes, column and free form extrusion (FFE) heat integration, substitution of refrigeration load with natural cooling and an in-line condenser cleaning system.

During the period 2013-14 to 2015-16, the company’s specific power consumption (SPC) reduced from 1,326 kW per tonne in 2013-14 to 1,028 kW per tonne. Specific thermal energy consumption declined from 2.2 million kCal per tonne in 2013-14 to 1.75 million kCal per tonne in 2015-16. Specific carbon emissions decreased from 1,478 kg per tonne to 1,159 kg per tonne.

The unit has three operational columns in the plant with different temperature and thermal requirements. The plant conserved thermal energy through heat integration (pinch analysis) using multi-column operation.

The company also adopted an innovative in-line condenser cleaning system to sustain the heat transfer coefficient. Prior to this, higher SPC was observed with every 4 °C rise in condensing temperature. This led to a loss of 10 per cent of energy. The unit adopted an in-line condenser cleaning system to sustain the SPC to the design value, and avoid manual cleaning and shutdown. The plant also substituted refrigeration with natural cooling. This eliminated the footprint of the large refrigeration system, power and water.

The unit replaced once through lubricated (OTL) vacuum systems with dry vacuum pumps. The implementation of dry vacuum systems has reduced power and steam consumption along with waste reduction. It has also led to higher equipment reliability and better operational control. Now solvent recovery is possible without energy consumption for the separation of waste oil. Further, this system consumes 30 per cent less power.

Apart from the above initiatives, the unit has installed a zero liquid discharge reverse osmosis (ZLD RO) system with 200 kilolitres per day (kld) capacity to recycle effluents and has become a zero discharge unit since May 2014. In order to eliminate steam for evaporation, the unit has installed a mechanical vapour recompression system (MVR), which increases the concentration of the RO reject from 1 per cent to 15 per cent, recovering 90 per cent water and reducing thermal energy by 90 per cent. The adoption of steam and water conservation by MVR has resulted in a ZLD RO reject of 10,000 parts per million total dissolved solids of 15-20 kld and evaporated through conventional evaporator utilising 16-22 tonnes of steam per day. UPL is the first agro-chemical company to have achieved ZLD with MVR.

UPL Limited, Unit 1, Ankleshwar, Bharuch district, Gujarat

Another unit of UPL located in Ankleshwar, Gujarat, has been recognised by the BEE for its energy conservation efforts in 2016. This unit started operations in 1980. It mainly manufactures monocrotophos, dichlorovos, trim ethyl phosphite, mancozeb, IKI and other agro speciality chemicals. The SPC of the plant reduced from 696 kW per tonne in 2013-14 to 628 kW per tonne in 2015-16. The specific thermal energy consumption of the unit declined from 2 million kCal per tonne in 2013-14 to 1.98 million kCal per tonne in 2015-16.

Some of the energy conservation measures adopted by the plant include steam and power reduction through the pinch analysis methodology. Using this analysis, the heat recovery potential of the ammonia stripper and recovery column was identified. The Ammonia Stripper-1 feed was pre-heated using the ammonia recovery column bottom stream. As a result, the unit saved 1,000 kg per hour of steam, the cooling water load decreased by 180 tonnes of refrigeration and the cooling water pumping power reduced along with 21 kld of water loss due to evaporation. The unit also adopted steam reduction through multi-column heat integration and reduced the column re-boiler steam load. Instead of discharging waste heat to the atmosphere, the re-boiler feed was preheated using the bottom withdrawal stream. This reduced the load of the re-boiler and decreased the consumption of steam by 400 kg per hour along with reducing the cooling water load.

The company uses the gravity flow system in all operating chiller systems. The water is circulated to processes using only secondary pumps, which ensures the minimum flow requirement of the chiller. It also has heat pipes for reducing the natural gas requirement using the waste heat of the exhaust flue gas. This has led to the reduction of natural gas by 15 standard cubic metres per hour and has reduced the flue gas temperature to 139 °C.

The plant has deployed the more efficient hybrid vacuum system in the place of steam jet ejector systems. Subsequently, the steam consumption of the unit has reduced significantly, from 1,800 kg per hour to 700 kg per hour with an additional power consumption of 70 kWh.

IOL Chemicals and Pharmaceuticals Limited, Barnala, Punjab

IOL Chemicals and Pharmaceuticals Limited, located in Barnala, Punjab, is a leading generic pharmaceuticals company and is a significant player in the organic chemicals space.

The company implemented a number of measures, leading to savings of 1.94 million kWh of electricity in 2015-16. These included the installation of spargers in the flash tank in the monochloro acetic acid (MCA) plant. The installation removed the dissolved uncondensed gases from the feed, which increased the vacuum of the MCA column. Further, by increasing vacuum in the column, the steam consumption in the distillation column decreased. The process resulted in a saving of 240,000 kWh of electricity annually and 6,868 tonnes of steam during the year. The unit saved a total of

Rs 12.84 million through the implementation of this project.

Another initiative was the use of high pressure steam condensate in steam tracing for replacing low pressure steam in the MCA plant. Earlier, this high pressure steam condensate was sent to the condensate tank. After the modification, the high pressure steam condensate was used in the steam tracing lines of the MCA plant to keep it in a molten state. Previously, low pressure steam was used for the process, which is getting saved now. Thus, with an investment of Rs 200,000, the plant saved 3,762 tonnes of steam worth Rs 6 million.

The company has also replaced the chiller with a cooler plate-type heat exchanger (PHE) in the final distillation column of the ethyl acetate plant. The chillers of the final distillation column of the ethyl acetate plant, which use chilled water as a cooling medium, were re-

placed with coolers of higher heat transfer area, which uses cooling tower water. This reduced the chilled water consumption of the ethyl acetate plant. By using this technique, the unit saved 473,000 kWh of electricity and 2,250 tonnes of steam worth Rs 7.24 million in 2015-16. The unit used flash steam generated from high pressure condensate as low pressure steam in the recovery section of the isobutylbenzene (IBB) plant. This reduced the low pressure steam in the recovery section and resulted in steam savings of 2,100 tonnes worth Rs 3.35 million.

Several other initiatives like the installation of additional cold oil PHE in the IBB plant utility section, the installation of a preheater in the acetyl column feed line in the acetyl chloride plant, and the use of a low-flow cooling water pump instead of a high-flow cooling water pump in winter were also taken by the company for optimising the use of energy.

Conclusion

The high cost of energy is one of the main challenges faced by players in the chemicals and petrochemicals sector. As the above case studies show, Indian companies are investing in innovative solutions to address this challenge.

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