| PetroChina Guangxi Petrochemical Company's 10MMTA refinery project(PhaseⅠ), as the first large refinery project invested by PetroChina in the southern coastal region of China, processes low-sulfur crude feedstock derived from Areas 1,2 and 4 in Sudan and adopts the Crude/Vacuum Distillation-Residue Fluid Catalytic Cracking and Unicracking process flow diagram. As the refinery is designed to process low-sulfur crude for PhaseⅠ, it's hard to ensure the crude resources due to the sulfur content in the crude. Meanwhile the price of crude is going up, the price difference between sour crude and low-sulfur crude is getting bigger which has resulted in affecting the enterprise efficiency since the refinery was put into operation. It is the development trend for a large and modern refining enterprise to take advantages of the refining enterprises located at the coastal areas, to process sour and high-acid crude, to ensure crude resources, to reduce the cost of purchasing crude and produce clean gasoline and diesel products which are in accordance with EuroⅣ/Ⅴemission levels.This thesis has made extensive analysis on the actual operating status of the existing units in PhaseⅠwhich have been put into operation, and has made study on processing sour crude in GXPC's refinery, and has studied the process scheme of the heavy oil when sour crude is processed. A clean and environmental integrated technology, the process flow diagram of Crude/Vacuum Distillation-Vacuum Residue Desulfurization-Fluid Catalytic Cracking and Unicracking, was determined after the research. The research result has shown that the integrated technology sufficiently incorporates the actual conditions of the existing units to achieve the stable transition from the existing to newly-built units and to achieve the overall objectives of GXPC's processing sour crude.It is a contradiction to process sour and high sour crude and to upgrade the product quality. This thesis has researched on the potential problems which may probably occur to gasoline and diesel products when sour crude is processed. The research result has demonstrated that the key to upgrade the quality of gasoline is to improve the quality of catalytic (FCC) gasoline. The current pre-hydrotreating measures (the product from VRDS unit) taken to FCC feedstock can't satisfy the requirement. The research on FCC heavy naphtha hydrodesulfurization technology has proven that the sulfur content in the gasoline can be efficiently reduced by adopting FCC heavy naphtha hydrodesulfurization technology, and minimum loss of octane number in gasoline can be ensured at the same time. The key to upgrade diesel product quality is to reduce the sulfur content and to improve cetane number. So the existing DHT unit cannot satisfy the requirement. The research made on DHT technology has shown that it can efficiently reduce the sulfur content in the diesel and improve cetane number of the diesel by building a new DHUG unit by utilizing MCI technology.It is critical for the enterprise to reduce the cost by utilizing entire hydrogenation technology and providing low-cost hydrogen to the whole complex. The study on the whole hydrogen supply system to the complex has demonstrated that while the best use of the low-cost hydrogen, CCR platforming net gas and purge gas are made, the optimized choice is to build a hydrogen product plant which natural gas is used as feed to assure the hydrogen supply to the complex. In order to be in accordance with the increasingly strict environmental emission standard, the research on waste water, waste gas and sulfur recovery is made in this thesis, and the result has shown that the sour water and sour gas will be treated or recovered by sour water stripping technology, mercaptan removing and Clause Sulfur Recover technology respectively, which can meet the requirement.The above-mentioned research results are very important for GXPC to process sour crude and are important references to be used by other refineries in China to process sour crude. |
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