(258g) Modeling and Optimization of Naphtha Pyrolysis Process Considering CO2 Emissions
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Computing and Systems Technology Division
Industrial Applications in Design and Operations
Monday, November 6, 2023 - 2:18pm to 2:36pm
An effective way to reduce greenhouse gas emissions is to decrease CO2 emissions from existing high-carbon emitting processes such as Naphtha Cracking Center (NCC). In NCC, a large amount of carbon emissions occurs mainly in the naphtha pyrolysis process due to flue gas from the furnace. Therefore, in this study, fundamental modeling and optimization of operating conditions have been performed for the naphtha cracking furnace in consideration of carbon emissions.
The outlet composition of the naphtha pyrolysis process significantly influences the yield of olefin products and the economic feasibility of NCC. Mathematical models have been developed to simulate and analyze the behavior of tubular reactors in naphtha-cracking furnaces [1, 2]. In addition, models for optimization and control purposes have also been developed [3, 4]. However, these models are not able to take into account the environmental influences of CO2 emitted from the flue gas for heat supply in the firebox. To this end, this study proposes a coupled model considering both the firebox of the cracking furnace to predict carbon emissions from the flue gas and the tubular reactors to predict the coil outlet attributes through the pyrolysis reaction.
More specifically, the system's structure was constructed based on the furnace configuration of Stefanidis et al. (2008) [5]. In order to consider the characteristics of the naphtha pyrolysis furnace with dispersed parameters, Hottel's zone method [6, 7] was employed to model the firebox by dividing it into several zones composed of isothermal surfaces and volumes with uniform characteristics. The proposed model also used a kinetic model including 133 reaction mechanisms proposed by Sundaram et al. (1978) [8] to consider the naphtha cracking reactions in the tubular reactors. The material balance and energy balance equations were developed by dividing the overall cracking furnace into four parts: (a) Furnace wall, (b) Flue gas, (c) Tube wall, (d) Process gas. Then, the model fitting was performed based on the operation data of a practical naphtha pyrolysis furnace in [2].
Based on the developed coupled firebox and tubular reactors model, optimization was performed to maximize the profit from the ethylene and propylene products while minimizing the economic loss due to the carbon tax for CO2 emissions from the flue gas. As a result, the derived optimal operating condition showed further improved results from the economic perspective than the conventional operating condition in which only the yield of the target olefin products was considered.
REFERENCES
[1] Haghighi, S. S., Rahimpour, M. R., Raeissi, S., & Dehghani, O. (2013). Investigation of ethylene production in naphtha thermal cracking plant in presence of steam and carbon dioxide. Chemical Engineering Journal, 228, 1158-1167.
[2] Barazandeh, K., Dehghani, O., Hamidi, M., Aryafard, E., & Rahimpour, M. R. (2015). Investigation of coil outlet temperature effect on the performance of naphtha cracking furnace. Chemical Engineering Research and Design, 94, 307-316.
[3] Yan, M. (2000). Simulation and optimization of an ethylene plant (Doctoral dissertation, Texas Tech University).
[4] Shahrokhi, M., Masoumi, M. E., Sadr, A. M., & Toufighi, J. (2003). Simulation and optimization of a naphtha thermal cracking pilot plant.
[5] Stefanidis, G. D., Van Geem, K. M., Heynderickx, G. J., & Marin, G. B. (2008). Evaluation of high-emissivity coatings in steam cracking furnaces using a non-grey gas radiation model. Chemical Engineering Journal, 137(2), 411-421.
[6] Eckert, E. R. G. (1969). Radiative transfer, HC Hottel and AF Sarofim, McGrawâ€Hill Book Company, New York.
[7] Rao, M. R., Plehiers, P. M., & Froment, G. F. (1988). The coupled simulation of heat transfer and reaction in a pyrolysis furnace. Chemical engineering science, 43(6), 1223-1229.
[8] Sundaram, K. M., & Froment, G. F. (1978). Modeling of thermal cracking kinetics. 3. Radical mechanisms for the pyrolysis of simple paraffins, olefins, and their mixtures. Industrial & Engineering Chemistry Fundamentals, 17(3), 174-182.
The outlet composition of the naphtha pyrolysis process significantly influences the yield of olefin products and the economic feasibility of NCC. Mathematical models have been developed to simulate and analyze the behavior of tubular reactors in naphtha-cracking furnaces [1, 2]. In addition, models for optimization and control purposes have also been developed [3, 4]. However, these models are not able to take into account the environmental influences of CO2 emitted from the flue gas for heat supply in the firebox. To this end, this study proposes a coupled model considering both the firebox of the cracking furnace to predict carbon emissions from the flue gas and the tubular reactors to predict the coil outlet attributes through the pyrolysis reaction.
More specifically, the system's structure was constructed based on the furnace configuration of Stefanidis et al. (2008) [5]. In order to consider the characteristics of the naphtha pyrolysis furnace with dispersed parameters, Hottel's zone method [6, 7] was employed to model the firebox by dividing it into several zones composed of isothermal surfaces and volumes with uniform characteristics. The proposed model also used a kinetic model including 133 reaction mechanisms proposed by Sundaram et al. (1978) [8] to consider the naphtha cracking reactions in the tubular reactors. The material balance and energy balance equations were developed by dividing the overall cracking furnace into four parts: (a) Furnace wall, (b) Flue gas, (c) Tube wall, (d) Process gas. Then, the model fitting was performed based on the operation data of a practical naphtha pyrolysis furnace in [2].
Based on the developed coupled firebox and tubular reactors model, optimization was performed to maximize the profit from the ethylene and propylene products while minimizing the economic loss due to the carbon tax for CO2 emissions from the flue gas. As a result, the derived optimal operating condition showed further improved results from the economic perspective than the conventional operating condition in which only the yield of the target olefin products was considered.
REFERENCES
[1] Haghighi, S. S., Rahimpour, M. R., Raeissi, S., & Dehghani, O. (2013). Investigation of ethylene production in naphtha thermal cracking plant in presence of steam and carbon dioxide. Chemical Engineering Journal, 228, 1158-1167.
[2] Barazandeh, K., Dehghani, O., Hamidi, M., Aryafard, E., & Rahimpour, M. R. (2015). Investigation of coil outlet temperature effect on the performance of naphtha cracking furnace. Chemical Engineering Research and Design, 94, 307-316.
[3] Yan, M. (2000). Simulation and optimization of an ethylene plant (Doctoral dissertation, Texas Tech University).
[4] Shahrokhi, M., Masoumi, M. E., Sadr, A. M., & Toufighi, J. (2003). Simulation and optimization of a naphtha thermal cracking pilot plant.
[5] Stefanidis, G. D., Van Geem, K. M., Heynderickx, G. J., & Marin, G. B. (2008). Evaluation of high-emissivity coatings in steam cracking furnaces using a non-grey gas radiation model. Chemical Engineering Journal, 137(2), 411-421.
[6] Eckert, E. R. G. (1969). Radiative transfer, HC Hottel and AF Sarofim, McGrawâ€Hill Book Company, New York.
[7] Rao, M. R., Plehiers, P. M., & Froment, G. F. (1988). The coupled simulation of heat transfer and reaction in a pyrolysis furnace. Chemical engineering science, 43(6), 1223-1229.
[8] Sundaram, K. M., & Froment, G. F. (1978). Modeling of thermal cracking kinetics. 3. Radical mechanisms for the pyrolysis of simple paraffins, olefins, and their mixtures. Industrial & Engineering Chemistry Fundamentals, 17(3), 174-182.