Design Of A Chemical Plant For The Production Of 100 000 Tons Year Of Cumene With 995 Purity PDF Download

Cumene is an aromatic hydrocarbon with various applications in the industry. The main purpose of producing cumene is to use it as a raw material for the production of phenol. The raw materials for the production of cumene include benzene and propylene. After researching the different methods to produce cumene, it was found out that the classical method uses solid phosphoric acid (SPA) or aluminum trichloride (AlCl3) catalysts, yet the modern method is more efficient and utilizes various types of zeolites. In this design project the catalyst chosen is beta zeolite since it provides the highest selectivity /yield and is the most environmentally and health friendly catalyst in comparison to the other catalysts normally used in the classical method. Additionally, beta zeolite provides the highest cost efficiency. The aim of this design project is to fully design a chemical plant that yields 100, 000 tons/year of 99.5% purity cumene from benzene and propylene. This process will involve the usage of two reactors, an alkylation and a trans-alkylation reactor, which are originally fixed bed reactors; this type of reactor is chosen as it preserves the catalyst and boosts the exothermic reactions. In this design project, it was decided that the by-product, DIPB, is to be recycled in the trans-alkylation reactor in order to produce the maximum amount of cumene only. The benzene and propylene enter the alkylation reactor at a ratio of 4.71:1 respectively and a temperature of 180°C, whereas DIPB and the excess benzene enter the trans-alkylation reactor at a ratio of 4:1 respectively at a temperature of 240°C. The conversion of the first reactor is 100% with respect to propylene while the conversion of the second reactor is 45% of DIPB. Also, the overall selectivity of the process is 94%. In this design project, there were certain steps to follow. For instance, after selecting the desired process based on the one that results in the highest selectivity and yield of cumene, the process flow diagram (PFD) based on research and literature was created using Aspen HYSYS. Next, the design of the equipment was completed with the help of certain programs, such as polymath. In brief, for the Carbon Steel alkylation reactor, its volume, diameter, and length are 37.31m3 , 2.48 m, and 12.39 m respectively. Moreover, 3.73 x 104 kg of zeolite is required for the alkylation reactor. As for the Carbon Steel trans-alkylation reactor, the volume, diameter, length, and catalyst weight are 4.53 x 10ˉ3 m3, 0.17 m, 0.33 m, and 4.53 kg respectively. Other significant equipment that are noteworthy to mention are the heat exchanger, two distillation columns, and flash separator. For the heat exchanger placed before the alkylation reactor, it has been chosen in this report to utilize the huge amount of heat accompanied with the outlet stream of the reactor since the reaction is exothermic to heat the inlet of the same reactor. This would help in saving energy and cutting down costs. For this integrated shell and tube heat exchanger, the hot fluid was placed in the tube side, whereas the cold fluid was located in the shell side. For the tubes, there are 4 tube passes with 102 tubes per pass; the nominal pipe size is 3/8 the inner and outer diameters are 0.0125 m and 0.017 m respectively, and the length of the tube is calculated to be 7.315 m. Furthermore, the pitch type is identified to be 0.021 triangular. As for the shell, the heat transfer area, internal diameter, and the baffle cut are: 160.23 m2, 0.57 m, and 25% respectively. For the first distillation column, the benzene column, that intends to separate benzene from a mixture of benzene, cumene, and DIPB, has a minimum reflux ratio of 3.44, 21 actual stages , a diameter of 1.23 m, and a height of 12.01 m, and the feed enters the column starting from the top at the very first stage. As for the second distillation column, similar values were found. Moving on to the single stage flash separator, which separates propane from the rest of the mixture, its height and diameter are 3 m and 0.74 m respectively. In order to achieve this process successfully, estimation of the cost must be made, where it was found that the total manufacturing cost of the plant is 120, 863,690 US dollars. The payback period (PBP) was found to be 2.41 years and the rate of return of investment (ROROI) equal to 21.1%. At the end, a HAZOP study was done on different equipment of the plant to identify any environmental, health, and safety hazards. Not to forget to mention, certainly, there were problems faced, such as unavailability of data or uncertainty, while working on this project: nevertheless, the team members managed to resolve any conflicts.