Study On Heating Furance Coke Inhibitor Of Delayed Coking

There is an obvious tendency that the crude oil exploited worldwide is becoming more and more heavy and low quality.It is a challenge for the refinery to process it with high economic benefits and environmental friendly.Delayed coking has the advantage in maturity of technology,wide adaptability in various raw materials,and low cost in equipment investment and processing expenses.But the phenomenon of furnace tube coking seriously affect its operating cycle,increase maintenance costs.Coke inhibitor is a kind of chemical additive which can not only restrain the production of petroleum coke and dry gas,but also can increase the yield of liquid.In the industrial production,the coke inhibitor is widely used.It is an imperative technical strategy for the refinary to strenthen the exploration the rule of the coke inhibition and new coke inhibitor R&D.By consulting literatures,four kinds of coke inhibitors were prepared based on compound composition and formulation optimization.Liaohe heavy oil was used as raw material to simulate delayed coking reaction.The coking reaction was carried out at 415?~500?.Coke productive rates,gas product composition,liquids composition of saturated hydrocarbon,aromatics,resins and asphaltenes analysis and liquids composition simulated distillation analysis were investigated and compared,after the delayed coking reaction in the case of adding / without coke inhibitor.Morphology changing of the petroleum coke was studied by using polarizing microscope,SEM and XRD.The applicability of coke inhibitor to different heavy crude oil was investigated.The main conclusions are reached as following:(1)The coking productive rate increases rapidly as the rising of the reaction temperature in the delayed coking.The coking productive rate of Liaohe heavy oil is 3.28%,12.23%,57.16% respectively,when the reaction temperature of delayed coking is 425 ?,460 ?,500 ? respectively.Corresponding to this,the coking productive rate of Shengli heavy oil is 2.56%,10.38%,36.84% respectively,when the reaction temperature of delayed coking is 425?,460?,500? respectively.(2)Coke inhibitor I prepared in this thesis has the optimal coke preventing effect.The coking productive mass rates decreased 23.93%,25.02%,27.25% for Liaohe heavy oil,when the reaction temperature of delayed coking is 425?,460?,500? respectively.Compared to this,the coking productive mass rates of Shengli heavy oil decreased 27.73%,28.52%,29.43% respectively,when the reaction temperature of delayed coking is 425?,460?,500? respectively.(3)Methane is the main component in the gas product,whose volume percentage decreased after the adding of coke inhibitor.Decrease rate of the methane volume percentage was 10.43%,24.45%,29.79% for Liaohe heavy oil,when the reaction temperature of delayed coking is at 415?,460?,500? respectively.As a comparison,decrease rate of the methane volume percentage was 10.96%,23.30%,23.72% for Shengli heavy oil respectively,when the reaction temperature of delayed coking is at 425?,460?,500? respectively.(4)Simulated distillation results indicated that adding of coke inhibitor increased the sum of gasoline and diesel.The enhanced rate of gasoline and diesel for Liaohe heavy oil is 5.62%,5.68%,5.86% respectively,when the reaction temperature of delayed coking is 415?,460?,500? respectively.Corresponding to this,enhanced rate of gasoline and diesel for Shengli heavy oil is 5.12%,5.30%,6.03% respectively,when the reaction temperature of delayed coking is 425?,460?,500? respectively.(5)As the rising of reaction temperature,petroleum coke block enlarged,observing from SEM photo.And rip between different petroleum coke block narrowed.Small block attached to big block decreased.Petroleum coke structure becomes loose and unstable,even becomes deformed,after adding the coke inhibitor.(6)As the rising of reaction temperature,petroleum coke block enlarged,observing from polarizing microscopic photo.More rip between different petroleum coke block occurred,after adding the coke inhibitor.And the petroleum coke block became slender and fragile and unstable,from which irregular border could be found.Coke inhibitor change the shape of petroleum coke and increase the gap between the coke and the coke to achieve the purpose of cleaning the coke.(7)XRD results showed that petroleum coke crystal structural parameter such as layer diameter and average layer distance did not change much,after rising of reaction temperature and adding of the coke inhibitor.The above variable only changed the macro morphology of the petroleum coke.Coke inhibitor change the shape of petroleum coke and increase the gap between the coke and the coke to achieve the purpose of cleaning the coke.In summary,coke inhibitor prepared in this thesis could decrease the coke productive rates and increase the liquids yields of gasoline and diesel,which has potential future in the industial application.