Control Structure Design and Dynamic Modeling for Atmospheric Distillation Column: Effect of Increase Capacity

The paper presents the computer simulation of a multivariate control algorithm. Industrial relevance is given as the problem is derived from a real plant, an industrial athmospheric distillation column at Shiraz refinery. The control performance of the industrial column using relative gain array (RGA) and relative normalized gain array (RNGA) configurations has been examined for nominal operating capacity and 10% increase in capacity. The results show that RNGA structure remains stable and has an acceptable control performance for both nominal and increased capacity. RGA structure unlike RNGA changes at the increased capacity and has some difficulties in crude oil switch scenario. It has also been shown that the furnace duty will increase considerably in the case of using RGA for operating at increased capacity. The results indicate that RNGA represents better decision for loop pairing and control structure selection and can solve control issues of industrial distillation column specifically for uncertain feed condition.