Estudo de tratamento de interface proveniente de polidutos

Abstract

The São Paulo Brasília Pipeline (OSBRA), owed by PETROBRAS, starts at the Planalto Refinery (REPLAN) and supplies gasoline, Diesel oil and liquefied petroleum gas (LPG) to the mid-west region of Brazil. The pipeline is 786 kilometers long with diameter of 20 inches in its first segment and 178 kilometers with 12 inches of diameter in the second. The fuels are pumped by seven unmanned pump stations and are delivered to five tank farms. Previously, these products were pumped into the pipeline in batches, those of Diesel or LPG located between gasoline batches. These sequences allowed the dilution of the transmix, which are mixtures generated between two products during the pipeline transportation, to the pure product tanks, keeping compliance to the former standards. The Diesel/gasoline transmix were mixed direct to pure product tanks of Diesel or gasoline. The LPG/gasoline transmix were submitted to flashing in a vessel before to be mixed into gasoline tanks or LPG spheres. The National Petroleum Agency (ANP) changed the Diesel and LPG standards, in 2001 and 2004 respectively. The properties which were altered are the flash point of the Diesel and the residues of the LPG. This new regulation turned the OSBRA installations unable to dilute the whole transmix volumes generated during pipeline transportation. Part of the transmix had to be sent back to the REPLAN, increasing the costs and making the LPG pipeline transportation unprofitable. To overcome this situation, a new product was developed the QINTER. The QINTER can be mixed in suitable rates either to Diesel or to gasoline keeping the compliance of these fuels to the new standards at the receiving tanks. The QINTER has been pumped into the pipeline between the batches of Diesel oil and gasoline since then. The standard solution to treat the mixture created between LPG and gasoline batches, which is a distillation tower, was studied, but it showed to be unprofitable and it would compel changes to the existing working schedule time, from Monday to Friday (6:00am to 10:00pm) to a 24:00h/day continuous work. In this thesis, there were studied three new configurations which would need lower capital investment and would not change the working schedule time. It was used the process simulator Petrox, developed by the Research Center of PETROBRAS, to carry out the necessary process simulations. In the first configuration it was studied the change of the actual treatment system operation, from batches to a steady state way, as well as it was made a search of the optimum pair of pressure and temperature operation of the existing system. In the second configuration it was included a new flash vessel in series with the existing flash vessel. In the third configuration it was added two flash vessels and two new heat exchanges to the existing system. The simulations which were carried out showed that in the three configurations studied the compliance with the new standards were achieved. Nevertheless, in the first configuration would be needed more time than the available in the current working schedule to treat the whole transmix generated in the pipeline transportation. The second and the third configurations provided the necessary capacity to treat the transmix. The advantage of the last one is the residue of its vapor stream to be within the standards. This feature turns the operational work easier, because it eliminates the necessity of controlling the proportion in that the vapor stream is mixed with LPG to keep compliance with the standards. Therefore, the desired target, to find technical and operational solution to treat the transmix volumes generated in the OSBRA transportation, was attained.