Feedstock pre-hydrofining unit

The light naphtha distillate was hydrorefined by the pre-hydrogenation reaction unit to obtain the refined light naphtha whose impurity content met the requirements of the continuous reforming feed. Then the pre-fractionator was used for rectification. The top of the tower was used as the C5/C6 isomerization feedstock,  the bottom fraction was used as the continuous reforming feedstock. For the combined unit, impurities in light naphtha after hydrorefining not only meet the requirements of reforming catalyst for feedstock technical indexes, but also meet the requirements of low temperature isomerization catalyst for feedstock technical indexes, requiring sulfur, nitrogen and other impurities mass fraction less than 0.3gμ/g, so the process control of prehydrogenation unit and hydrogenation catalyst selection is very important.

For continuous reforming device, due to the cancellation of benzene extraction device of reforming products, in order to ensure that the benzene mass fraction of reforming products is not greater than 0.91% of the control index, continuous reforming feedstock in benzene forebody (C6 alkane + methyl cyclopentane + cyclohexane) mass fraction is less than 0.2%, the initial distillation point is not less than 105℃. For C5/C6 isomerization unit, in order to ensure the yield of isomerization products and the operation life of isomerization catalyst meet the technical control index, the mass fraction of C7+ fraction in C5/C6 isomerization feedstock is required to be less than 3%. In order to make the operation of the pre-fractionating tower meet the control index of the top and bottom materials, it is necessary to further improve the separation accuracy of the pre-fractionating tower. The number of the separation tower plates is increased from 30 to 70. Combined with the adjustment and fine operation of the operating temperature of the top and bottom of the tower, the feedstock requirements of continuous reforming and C5/C6 isomerization device can be met at the same time.