Optimal Process For Raffinate Of Pyrolysis Gasoline Used As Feedstock For Reformer

Catalytic reforming is a major petroleum refining process to convert naphtha into high-octane gasoline or aromatics. Recently, in China, with the development of catalytic reforming industry, feedstock(naphtha) shortage becomes the main restricting factor. How to extend and optimize the feedstock of reformer is the most important factor for the development of catalytic reforming. Raffinate of pyrolysis gasoline is the preferred feedstock for reformer attribute to its high potential aromatics. Unfortunately, most of the raffinate are returned to the pyrolyzer to pyrolyze again. It is not a profitable way compared with raffinate used as feedstock of reformer.Two problems may emerge when pyrolysis gasoline used as feedstock for reformer. The first problem is with the addition of pyrolysis gasoline, S content in the feedstock may above the specified standard, this may cause the poisoning of reforming catalysts. The second is Si content in the feedstock may also above the specified standard and may also cause the poisoning of reforming catalysts. Based on the operation results of naphtha hydrotreatment, compared the amount of raffinate with that of the naphtha used as feedstock, the addition of raffinate into naphtha won't affect the operation of reformer unit, the S and Si content in the mixture meet the specified standard..Three schemes are introduced. The 2nd one is the most preferred one which combine the benefit, investment, convenience for operation, impact to the reformer unit together. Raffinate of pyrolysis gasoline is sent to the BPX unit through the line from the bottom of column T-101, and is mixed into the reforming feedstock in tank T-50401~3. The mixture is pumped into the reactor for hydrotreating where the mixture was hydrotreated and the impurities are removed, the mixture was sent to the stripping tower before it was sent into the reforming reactor.After a series of device remodeling, the scheme was put into effect in November 2004. A series of results were obtained after about two months of work. The results show that no impact to the reformer unit was detected after the raffinate of pyrolysis gasoline had been mixed into the reforming feedstock. The results obtained before and after the raffinate was mixed into the feedstock show that with the addition of raffinate, benzene content in the reformate increased 0.91wt%. With the addition of 40t raffinate everyday, we benefit $66000 yuan,we'll benefit $23.76M yuan every year from the addition of pyrolysis raffinate.