Simulation and feasibility analysis of structured packing replacement in absorption column of natural gas dehydration process: A case study for Farashband gas processing plant, Iran

Application of structured packing in separation processes like natural gas dehydration has been increased since last few years. Replacement of the existing trayed column with that of structured packing can enhance the capacity and performance of the natural gas dehydration process. In this work, the natural gas dehydration plant of Farashband gas processing plant has been simulated. The profile of concentration, temperature and pressure in absorption column was obtained. A computer program, prepared with Visual Basic, has been proposed to calculate the height equivalent to a theoretical plate (HETP) of structured packing. The effect of some important parameters of inlet Tri-ethylene glycol (TEG) and natural gas on the performance of absorption column have been analyzed. Results show that revamp of trays with structured packing, can reduce outlet natural gas dew point and improve the positive effect of other parameters on the performance of dehydration unit. Moreover, the most significant factors affecting the HETP were investigated which were less than 15% effective. Finally, the cost of the modification project for the absorption column in the Farashband gas processing plant was calculated. The cost is evaluated 202,909 $ in this case and replacing was found economically justifiable.