Largest Phthalic Anhydride Producer of Latin America uses PROFIBUS PA (Brazil)


PETROM, located in Mogi das Cruzes City, in Sao Paulo State, employs 190 workers approximately and with the new investments the plant will have an annual production capacity of Phthalic Anhydride of 80,000 tons, 90,000 tons of Plasticizers and 3,600 tons of Fumaric Acid. More than 100 field devices were supplied by smar for a PROFIBUS PA process automation solution in the largest Phthalic Anhydride producer of Latin America located in Brazil.


Goals and System Design


The need to increase Phthalic Anhydride production and the need to provide a better performance of reactors took Petrom to invest in the automation to improve the process control and also to increase the safety. These requirements could be reached using a reliable control system.

The system automation was designed to control 3 Phthalic Anhydride reactors and a vacuum distillation tower, totalizing 1200 I/O points. The advantage of having the interfaces, field devices and the controller near to the application reduced considerably the installation costs. The conventional instrumentation was integrated using ET200M interfaces.


40 % reduction of costs


In terms of network cabling, the PROFIBUS DP segment has 800m and the PROFIBUS PA has 1300m. Althoug the cost of PROFIBUS instrumentation is higher than the conventional one, the costs were absorbed by the reduction of commissioning and startup time, simple and fast diagnoses and maintenance of the system.

The main gain in terms of installation in this application due to PROFIBUS is concerning to the cable reduction due to the decentralized panel, the panels and conduits reduction. If the system was implemented in conventional 4-20mA technologies, it will be necessary more than 15,000m of cables for digital and analog signals. With PROFIBUS use there were 40% of reduction of costs in terms of installation.

The cost of PROFIBUS automation is about U$520,000.- including software configuration and field mounting. This corresponds to 15% of investments in the first step of total project, divided in six steps. In the first step are included 43 control loops, 400 I/O points and 385 analog inputs. In the engineering there were not so expressed costs since Petrom did all work with an initial support from CBTA Company and smar.


System Architecture


The system architecture contents two PROFIBUS DP network, one to control two reactors in the Phthalic Anhydride area and other to controls the third reactor and the vacuum distillation tower. Two CPUs CP416-3, two cards CP443-5 and two Ethernet cards CP443-1 where utilized and the baud rate is 1.5Mbits/s working perfectly.

The topology of PROFIBUS PA segments was done using tree topology and the spurs have several lengths. There are 9 links IM157 with 9 DP/PA couplers with a maximum of 21 field devices in each segment. Besides that, there are 16 IM-153 (ET200M), 3 frequency inverters, 13 Motors drive, 8 ASI gateways and repeaters, all of them from Siemens. There also devices from Westlock, Sense and P+F in the Asi network.


Further Devices Used


Further devices used were: JM1 (Junction Box), Pressure and Level Transmitters (LD303), Temperature Transmitter (TT303), Density/Concentration Transmitter, as well as Positioners (FY303). In the control room there are 3 stations for supervision, one for engineering and the other workstations. The control is done using PCS7 and Wincc graphic software. The PROFIBUS PA segments configurations, where are located the more than 100 field devices were performed using Simatic PDM tool.


Conclusion of the End-User


The new plant is operating since second semester of 2002. "The challenge of implementing this new technology in an operating plant was recompensed by the fact that future implementations will become simple tasks. Besides that, the training of all involved persons made work with PROFIBUS very easy. When Petrom assumed the project engineering gave us the capacity to know all details of installation, configuration and the opportunity to change the structure for better performance always when necessary. System interoperability and startup were excellent and the plant is operating very fine in its first step. The cost reduction and the simplicity of Profibus were confirmed and now we are observing maintenance behaviors, which also show a great improvement. Petrom has Smar as a technologic partner due to the quality of field devices during the time. This partnership brings us benefits since the technical support provided during the specification phase in the application and also after sales has contributed to keep a high operational availability of our plant. We are looking forward to the next plant steps", says the Petrom automation technician Marcos A. Cusma.

For more information, please visit http://www.profibus.com.