CEW Features
Sulfur Plant Management in a Petroleum Refinery The Crude slate is gradually widening. While at the same time the Sulfur specs and emission norms around the world are getting more stringent. In spite of the thrust for renewable and other alternate energy sources there will be a steady growth in fossil fuel in the coming decades. Hence there is an inherent need to have a closer look at the Sulfur Recovery Process in existing and new Refineries. Technology developments are being done at Licensors’ end, but Refiners are also looking for optimization in design with adequate flexibility in operation. Typically, while the refinery configuration gets finalized based on the available crude slates and the market demands of the products, a few important decisions need to be made regarding the Sulfur Recovery Unit. These are linked mainly with respect to SRU Plant capacity, configuration, technology and product management. This paper will highlight and discuss these issues; and provide means and methods in making these decisions early in the project lifecycle.
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he environmental effects of burning hydrocarbon fuels have led most world governments and environmental bodies to impose stringent specifications on the sulfur content of hydrocarbon fuels. And these emission norms are gradually getting more and more stringent, requiring tighter specifications for hydrocarbon products. The chart on the right clearly demonstrates how in the last two decades the sulfur specifications have become tighter, while at the same time the crude slate is gradually shifting towards high sulfur crudes. This creates additional challenges to design and improve the treatment process of various distillates but also develop and implement better means and methods to recover that sulfur. Hence the proper design of a Sulfur Recovery Unit (SRU) becomes vital from the very initial stage of a project. From the very inception of the project, when the blueprint of the refinery is being prepared based on the available crude slates and the planned products as per the market demand, a few key decisions need to be made with respect to the design of the SRU. This holds good for Refineries planning to undergo a revamp either to cater to a wider crude slate or to meet the newer emission norms. An early and proper judgment of these important parameters provides a smoother path of engineering and beyond in the lifecycle of the project. This paper intends to discuss 12 • October 2017
these parameters and provides guidelines to find answers to these questions. The Sulfur Recovery Process: The following simplified flowchart demonstrates how sulfur travels in a Refinery starting from the crude oil till getting recovered as liquid sulfur. The sulfur compounds present in the crude ultimately gets displaced from the hydrocarbon phase as H2S and that
is captured by an amine solvent in the amine treatment units or gets dissolved in the water. The amine circulates in the Refinery in a closed circuit, capturing the H 2S from the hydrocarbon phase in various amine treaters. This rich amine (rich in H 2S) is then regenerated in the Amine Regeneration Unit (ARU) to liberate the H 2S gas and generating lean amine (lean in H 2S) to be circulated back to the various amine treaters. Similarly, the sour water generated from the various process units in the refinery is treated in Chemical Engineering World