Extensive Simulation Analysis And Energy Usage Optimization Of The Atmospheric & Vacuum Distillation Unit

Petrochemical industry is considered one of the most important contributors to the economic development since many manufacturing industries rely heavily on the energy and raw material it provided. Atmospheric and vacuum distillation generates raw material for secondary processing operations as well as qualified for-sale products, thus there is no doubt it to be the primary processing unit when it comes to petroleum refining. However, the atmospheric and vacuum distillation unit is also the major obstacle for modern refineries to lower the energy consumption and operating cost since it is the major energy consumer, which takes up to 25~30%. In order to meet new challenges in the market, certain measures must be applied to lower the energy usage. The thesis paper is based on the optimization of energy usage in the atmospheric and vacuum distillation unit.A numerical simulation model of the atmospheric and vacuum distillation unit is created with the commercial software Aspen Plus based on the current condition of the oil refinery. True boiling point distillation data of the crude oil feed is used as input parameters, which properly characterize the properties of the crude despite its complexity in content. Certain modules and thermodynamic theories are chosen to represent each unit operations with appropriate parameters derived from the actual operating conditions of the oil refinery. The heat exchangers, which are considered to be the key unit of this optimization process, are simulated with Aspen Exchanger Design & Rating software, the one that is embedded within the Aspen Plus software suite, inside of which all the parameters required to design and operate a heat exchanger are presented, including geometric dimensions and heat resistance. Certain calculation results are sent back to the main program whichare in good agreement with actual data collected onsite, indicating the simulation is reasonable, which will provides an insight to the later optimizing process. The energy and exergy balance flow sheets and related charts are created according to the three-link energy consumption model that includes energy conversion, technical energy usage and energy recycle. Calculation results indicate relatively high energy conversion efficiency (83.59%) but low exergy conversion efficiency (50.75%), among which the exergy loss in fume is quite high (70.33%). Besides, the energy and exergy recycling is inefficient, with the recycling ratio of 59.35% and 41.13%, indicating much of the energy is not properly used.Multiple optimization schemes are proposed in order to lower the energy waste and to increase the profit,based on the simulation data of the atmospheric and vacuum distillation unit, toghether with three-link energy consumption model as reference, which could definitely guide the actual operation.