| Petroleum is a kind of non-renewable resource.With the rapid growth of world economy,demand for petroleum has been increasing quickly.Under the circumstance that conventional oil resources are increasingly rare,the exploration and exploitation of unconventional oil resources is accounting for 70% of global oil resources now.Therefore,the direction and requirement of energy development is to process low quality petroleum.Delayed coking process is a thermal processing technology for treating heavy oil.This technology has its own unique features in processing heavy and low-quality oil,such as its mature technology,fewer invest,low cost,good adaptability to all kinds of feeds,high diesel and gasoline yield and so on.There is a sort of delayed coking unit(abbreviated DCU)which is designed to directly process heavy crude oil.The basic properties of heavy crude oil and the nature of distillate oil were firstly analyzed to get a comprehensive understanding of the feedstock after researching of several China domestic refineries’ heavy crude oil DCU.And then Fulla heavy crude oil of Sudan block 6 was evaluated.The results showed that it has a higher density and its light oil yield is low.Furthermore,the content of nitrogen and acid are high.Meanwhile,the metal in crude oil,such as nickel,calcium,sodium and magnesium are high.Such a high acid and calcium content gives rise to the great difficulty in the process of crude oil.Conventional processing rout for routine crude oil has been difficult to deal with these types of heavy crude oil.Fulla heavy crude oil of Sudan block 6 is the feedstock of delayed coking unit(abbreviated DCU)of Khartoum refinery company limited(abbreviated KRC).The reason using delayed coking process to treat this type of oil is analyzed.The results showed that the processing scheme should improve the diesel yield and reduce the gasoline production to adapt to the Sudan market demand.Therefore,DCU technology can drastically decrease the content of acid in distillate oil and it means that the 95% acid is removed by using delayed coking technology.Otherwise,the yield of gasoline and diesel are more than 60%.It is noteworthy to underline that the yield of diesel reaches more than 40% which is suitable for market demand for diesel.As a result,delayed coking is a highly effective way to process high-acid heavy oil from Sudan block 6.By means of study on KRC’s DCU technology,operation conditions,product distribution and mass balance,summarized it’s main features..whether the initial design or the actual operation of the plant,heavy crude oil DCU in Sudan KRC has its own unique characteristics,this paper mainly research for analysis of the operation of the unit from the types of corrosion and corrosion prevention strategy,product distribution,actual operation effect of furnace,ctual operation parameters of coke drum and the start & shutdown.In addition to the common corrosion existing in conventional DCU,such as sulfur corrosion under high temperature condition,hydrogen sulfide corrosion under low temperature condition,dew point corrosion,KRC DCU include sulfur and naphthenic acid corrosion.That is why heavy oil DCU need higher-class material.The furnace in KRC’s heavy crude oil DCU has lower steam injection rate and lower furnace coking tendency in contrast to residua DCU furnace because of the existing of 350℃-500℃fraction in its furnace feed.Based on product distribution of two different kinds of DCU,the oil gas linear speed in coke drum under the same operation condition was calculated.These data provide theoretical guidance for the study of the different phenomena of the two different feedstock DCU. |
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