Production Of Terephthalic Acid Process Simulation

Purified terephthalic acid (PTA) is the important feedstock in production of polyester. Usually in the first step of the process, crude terephthalic acid (CTA) is obtained via catalytic oxidation of liquid p-xylene with air. And then CTA is purified by hydrogenation. Presently, PTA production technology is employed in high price, which influences production costs and market competitiveness. With basic research on chemical enginerring, process simulation software development of PTA production to form localization technology has great significance.The paper focuses attention on simulation of CTA production section. On the basis of each section simulation, CTA production process simulation is completed. Through comparition between simulation results and industrial value, accuracy and reliability of simulation are verified.Process of CTA production contains four parts, which are PX oxidation section, continuous multistage TA crystallization, acetic acid recovery, CTA drying and separation process. Simulation of oxidation reactor adopts the CSTR model in process simulation software and developed two-bubble class model. The numerical results of both models agree with real data. Two-bubble class model is more accurate, but data dependency.The model of crystallizer is set up using process simulation software. The results of material and heat balance calculation accord with industrial data and value of CSD is reasonable. It has more low precision than developed user model, but suits for prosess simulation.Both recovery of acetic acid and CTA drying and separation process are simulated using software of process simulation. Due to the non-ideal gas-liquid behavior, NRTL-HOC and NRTL-RK model are used in solvent dehydration tower and entrainer recovery tower. Filter and dryer are replaced with Swash and Flash2 model. The calculation results and industrial value are in accordance, which proved reliability of model.Above method of model are applicated in CTA production process simulation. The results are consistent with the operating data, which provide evidence for process design and optimization.