Identifier: TFG:2330
Authors: Hernandez Aldabo, Nadia
Abstract:
BASF SONATRACH PropanChem, S.A. Company, located in the industrial complex of Entrevies in Tarragona, wants to install a purification unit of FCC propylene in the propane dehydrogenation plant. This flow of FCC propylene comes from a catalytic cracking process and has a composition of 75% propylene, 22% propane and 3% of impurities, which must be removed. Mainly, the arsine is between this impurities and this product represents a strong poison for the catalyst of the process of dehydrogenation. As a result, it have been designed a purification system of the FCC propylene that arrives at the plant of Tarragona by boat from Castelló. It is designed three serially adsorbents for which passes the propylene at 25 ºC and 18 bar of pressure, removing impurities from the stream, this can be done through to the different adsorbents that are aluminum found in each vessel. The first vessel removes oxygenated compounds, mercaptans and water of the stream; then, in the second it will be removed the arsine, and finally, in the last vessel it will be adsorbed CO and CO2. After a period of about a month, the adsorbents will be saturated, i.e., may not adsorb more compounds, so they must be regenerated. Regeneration takes place through a process called Temperature Swing Adsorption, this process is done through a series of desadsorption at a higher temperature than the adsorption to change the equilibrium and ensure that compounds adhered to the adsorbent, go to the stream of nitrogen that will flow through the column. Thus, it has been designed the various equipment required for the process except the oven, which is necessary to heat the nitrogen required for regeneration. Within the adsorption system is designed centrifugal pump that will promote the FCC propylene, which is stored in a tank outside the park to the vessel. For the regeneration system, it has been designed a centrifugal compressor that makes nitrogen circulates in a closed cycle during regeneration. This must be cooled before to enter again to the compressor, so it has also been designed a shell and tube heat exchanger to decrease the temperature of the nitrogen stream is recirculated. It has also carried out the design of the control system of the entire plant and the pipping system. In addition, it has also made an environmental impact study to determine what effect will have on the environment the implementation of this project and determine the measures to be taken. To ensure the process safety, it has been used Hazop methodology in order to identify hazards and risk situation within the system of operation of the plant. Finally, to assess the economic viability will mean the implementation of this project has been an economic study in which it has calculated two economic indicators such as Net Present Value (NPV) and Internal Rate of Return (TIR), obtaining a value of 29 million of euros and 41.5%, respectively. There has also been done an economic sensitivity analysis to see how small changes affect some of the items considered in the economic balance.
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