Study On The Prediction Methods For Product Distribution Of Delayed Coking

The product distribution is an important parameter of economic benefit in delayed coking units.The prediction of product distribution is useful for the operation optimization,estimation of process scheme and techno-economic evaluation.Because coking reactions are complex,the conventional empirical models can not predict exactly the product distribution.Based on the investigation of static experiments,the prediction methods combined experiment and correction were developed,the effects of experimental conditions,structure and operation conditions were studied.The research of static experiments was made by using the special heavy oil thermal processing evaluation device.It was studied that the effects of the raw material quantity and the reaction mechanism conditions for the product distribution.The superior experimental conditions were developed.On condition that the amount of raw material is 7-8 g,and the reaction time is 30 min at 430 ? and 90 min at 500?,the experimental results are close to the actual data.The results of 16 kinds of heavy oil showed that the difference values of product distribution between the experiment and industrial units are 0~3.04%,-10.05~-2.4%,0.8~6.55%.The commercial performance tests of eight delayed coking units were made to research the effects of unit's structure and operation conditions(reaction temperature,reaction pressure and so on).The results showed that the range of operation conditions is small and their effects for product distribution are also small.And the results of the special unit showed that the range of unit's structural effects is 0.92-3.05% in the same operation conditions.In order to use the data about the industria and experimental product distribution for predicting industrial product distribution quickly and effectively,the concepts of referenceunits and reference oils were putted to develop the prediction methods: a referential differential method,a referential proportional method.The absolute errors of the referential differential method for gas yield,liquid yield,coke yield are that 0.44%,-1.5%,1.06%.And the absolute errors of the referential proportional method for gas yield,liquid yield,coke yield are that 0.67%,-1.69%,1.02%.For the delayed coking units with great differences with reference units,some correction of operation condition was made.Based on these correction,a complex differential method and a complex proportional method were developed.The absolute errors of the complex differential method for gas yield,liquid yield,coke yield are that 0.55%,-1.62%,1.07%.And the absolute errors of the complex proportional method for gas yield,liquid yield,coke yield are that 0.81%,-1.80%,0.99%.