Modeling of delayed coker unit

Delayed Coker Unit (DCU) converts the vacuum residual feedstock to lighter and more valuable products such as motor fuels and eliminates the low-order, environment-damaging streams. Thus, optimal operation of this unit provides great economic return. In this thesis, models have been developed to build a base for the future optimization and control studies of an industrial DCU which exists in the TUPRAS Refinery. In the unit, flow starts from the bottom of the main fractionator column, passes through coking furnaces and then coking drums and pours back in the main fractionator column. In the first part of the thesis, fractionator bottom and coker furnace models are provided. Fractionator bottom model is created on the Aspen Hysys simulation program. The designed furnace model, on the other hand, is formed based on steady-state, multi-phase and Euler-Euler approach. It is assumed that all reactions occur in the liquid phase, coke is not formed as a result of cracking reactions and the reaction products are formed in small amounts as gas phase. The actual operational output temperature and pressure values of the furnace and the model prediction results are very close. One of the most important equipment of the coking unit is coke drums, which are periodically changed and put into operation. Thermal decomposition takes place in coke drums and the vacuum residue turns into white products and coke. In the last part of the thesis, steady-state models of coke drums are developed. The steady-state model is constructed assuming the coke drums as a trickle bed reactor, in which the gas and liquid flow proceed through the reactor, while the coke bed remains motionless like the catalyst. The obtained steady-state model was used for predicting the coke particle diameter and the distribution of the products at the outlet of the coker drums. Coke drum model was verified by comparing obtained results with actual plant data.