Challenge
The Emirates National Oil Company (ENOC) manages a refinery, called the ENOC Processing Company (EPCL). It is based in Jebel Ali, in Dubai, and has been operational since 1999. The refinery uses different hydrocarbon feedstock to manufacture jet fuel, liquefied petroleum gas, butane, diesel, naphtha and other products.
Within the refining process, naphtha hydro-treating is an essential step to produce cleaner gasoline from oil or gas. While this is a crucial step, it also is an energy-intensive process, which a few years ago, in fact, called for the construction of an additional furnace to meet Dubai’s increasing energy demand – a course of action that would result in an increase in utility costs.
Strategy
In an effort to find a solution, the EPCL team engaged in a de-bottlenecking project in 2013. After considering the environmental and commercial factors, the team decided that the installation of an additional furnace was not the best course of action, considering that the contaminants stripper and naphtha splitter sections are substantial consumers of heating utilities.
The initiative has resulted in operational cost savings amounting to USD 840,000 a year
As a result, the team developed a waste heat system within the existing furnaces. Heat is simultaneously a natural resource and a byproduct of the refining process. The process in the system the EPCL team developed involved recovering heat in the heavy naphtha stream from the naphtha splitter section and, then, redirecting it towards air and water coolers. Typically, in essence, the solution of waste heat recovery in conventional naphtha hydro-treating processes significantly reduces the amount of energy consumed.
Results
In this case, the EPCL refinery saw many benefits. The energy demand from Natural Gas consumption, for example, was reduced by 0.52 million standard cubic feet per year. From an environmental perspective, the existing flue gas temperatures were also reduced from 250 degrees C to 150 degrees C. As for the environmental benefits of the system, the project has also mitigated 11,000 tonnes of carbon dioxide every year. Further, the initiative has resulted in operational cost savings amounting to USD 840,000 a year, specifically owning to reduced consumption of Natural Gas.
To date, the waste heat recovery system continues to ensure more efficient energy usage along the lifetime of the naphtha hydro-treating plant.
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