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Innovative design helps PCS increase output without increase in energy usage
A MODIFICATION to a piece of equipment at Petrochemical Corporation of Singapore (Private) Limited's (PCS) plant led to an increase in production while using the same amount of energy. The project resulted in an overall improvement to its energy efficiency and also won it a Best Practices nod at this year's EENP Awards.
Established in 1977, PCS is a pioneer in providing basic feedstock to the polymer and chemical industries in Singapore and Asia. The company is owned by Japan-Singapore Petrochemicals Company Limited (JSPC), together with QPI and Shell Petrochemicals (Singapore) Pte Ltd.
Over the years, the company's production capacity has increased more than threefold through debottlenecks, expansion and diversification efforts.
During a review on pressure control schemes at one of its plants, PCS found that one of the reactor feed drums, D-1, had a different design due to its lower elevation. Such drums act as a buffer to ensure a steady flow rate of reactants to the reactor.
As a result, the drum had to operate at a higher pressure than usual and consume more energy.
PCS sought to address this issue by making modifications to the drum's design. Drum pressure is traditionally controlled by injecting nitrogen gas to the drum and flaring the non-condensable gases downstream of the process. Known as the "push-pull" pressure control, this method is less energy efficient given the configuration of D-1 compared to other control methods as valuable hydrocarbons are being flared in the process.
To eliminate flaring and improve energy efficiency, PCS carried out a series of design modifications to the drum which enabled the recovery of the plant's hydrocarbon by-products - which was previously lost as part of the production process - without having to consume more energy. This made the process more energy efficient; which is defined as production divided by energy consumption.
The modifications were carried out without major equipment or structural changes.
As a result of the project, PCS successfully reduced the downstream flaring, resulting in an annual energy savings of 1.7 TJ, which is equivalent to a 3.3 per cent improvement at system level and a reduction of 1.62 kT of carbon emissions.
Various challenges were faced during this project.
Said Francis Tan Kok Vui, PCS energy manager: "At the conceptual stage, this idea was not proven by similar plants or even by the process licensor elsewhere. This made it difficult to convince management to invest in the capital expenditure. A trial was first carried out which proved successful and convinced management to invest in the project,"
During the trial and final implementation, the team also had to convince operators to adopt this new mode of operation.
Said Mr Tan: "This was overcome by ensuring close monitoring and communication with the operators and promptly addressing any concerns they had."