SINGAPORE-BASED ExxonMobil Asia Pacific Pte Ltd has bagged two awards at this year's Energy Efficiency National Partnership (EENP) awards. It has been recognised for best practices at the crude distillation unit - overhead waste heat recovery project at its Singapore refinery in Jurong, and got an honourable mention in the same category for its energy optimisation efforts through application of model predictive control (MPC) at its chemical plant on Jurong Island.
The project at the refinery involved the replacement of existing shell and tube heat exchangers with welded plate heat exchangers. It resulted in annual savings of more than S$2 million, based on the 2015 average of Singapore's energy price. The project team carried out several technical modifications to customise the design of the welded plate heat exchangers.
The chemical plant project involved using MPC to optimise various processes, thereby reducing energy consumption. Multiple parameters such as pressure, temperature and heat integration can be adjusted concurrently to optimise the processes. The project resulted in annual cost savings of about S$9.5 million, based on the 2015 average of Singapore's energy price.
ExxonMobil says that improving energy efficiency is important for the environment and its business. And it has a disciplined approach to improving energy efficiency at all of its manufacturing facilities. Since 2000, the company has used its Global Energy Management System (GEMS) in its petroleum refining and petrochemical businesses to identify and act on energy saving opportunities. Through GEMS, ExxonMobil has improved its energy efficiency at the Singapore refinery by 17 per cent and at the Singapore chemical plant's first ethylene cracker by 21 per cent over 12 years to 2014. That is the equivalent to removing 290,000 cars from Singapore roads from 2002 to 2014.
"We continue to harness technology to use energy more efficiently in Singapore. Our second steam cracker at the Singapore refining and petrochemical complex can process an unprecedented range of feedstock, including crude oil. Converting crude directly to chemicals saves energy and reduces emissions by eliminating the refining steps required to produce naphtha - this is the most energy efficient cracker in ExxonMobil's manufacturing circuit," says David Hergenrether, ExxonMobil Singapore chemical plant technical division manager. "We also have cogeneration facilities at the chemical plant here; with a total capacity of 360 megawatts, these facilities can meet all the energy needs of our petrochemical complex."
Cogeneration is the simultaneous production of electricity and useful heat or steam used for industrial processes, and is significantly more efficient than traditional methods of producing steam and power separately, and results in lower greenhouse gas emissions and cost.
Mr Hergenrether says that ExxonMobil's efforts to improve energy efficiency go beyond its operations. "We invest in technologies and produce a range of products globally that allow our customers and consumers to become more efficient themselves, reducing their costs and carbon footprint."
A few examples are:
- ExxonMobil produces halo-butyl that helps inner tyre-liners retain air for longer. The tyre-liner technology increases vehicle fuel economy with its superior air-retention capabilities.
- The company's advanced synthetic lubricants not only improve vehicle engine performance and extend oil drain intervals, but also reduces engine friction and increases mileage.
- At the same time, industrial lubricants help customers extend equipment life, reduce maintenance and improve efficiency within their operations.
- ExxonMobil's advanced plastics and materials save energy by reducing weight across a broad range of applications, including packaging and consumer products and vehicles.
The company says that it is pleased and honoured to have won both the EENP Best Practices award for its Singapore refinery project and an Honourable Mention in the same category for its efforts at the Singapore chemical plant.
"The winning efforts underscore the critical importance of continuous improvements, and working together to identify and implement the right opportunities. At the Singapore refinery, we were able to recover overhead heat and in turn cut the energy consumed by the furnace of one of our crude distillation units by more than 8 per cent," says Lai Man Wai, ExxonMobil Singapore refinery technical manager.
This was done by replacing the old shell and tube heat exchangers with welded plate ones. These welded plate exchangers are more compact, and yet at the same time, also have more surface area, so that more heat can be recovered. This recovered heat, which would have been lost otherwise, in turn increases the temperature of the furnace. "It was the first time we used welded plate heat exchangers at the refinery in Singapore, and we are currently evaluating the installation of welded plate heat exchangers at the other units in the plant," adds Mr Lai.
LOWERING ENERGY NEEDS
The Honourable Mention is for a trio of projects at the Singapore chemical plant - in applying the advanced technology called MPC. By doing so the company is able to optimise its energy needs over a range of operating conditions by managing multiple (operating) parameterssimultaneously.
MPC has been in use in ExxonMobil's olefins plant in Singapore since 2003, and won an EENP Best Practices award in 2013 for its application in an upgrade project.
"This year, we highlighted the energy savings from three MPC application projects: the extractive towers at our aromatics plant now use 5 per cent less energy than before MPC was used, and our olefins recovery units and propylene refrigeration system now have lower chilling requirements, leading to lower energy needs of 3 to 8 per cent," notes Mr Hergenrether.
ExxonMobil has been operating in Singapore for over 120 years. With more than S$20 billion of investments, it is one of Singapore's largest foreign investors, and employs more than 3,300 people. ExxonMobil's largest integrated refining and petrochemical complex is in Singapore.