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2 Utilization via Dry Reforming of Methane
Published in Subhas K Sikdar, Frank Princiotta, Advances in Carbon Management Technologies, 2020
Mohamed S Challiwala, Shaik Afzal, Hanif A Choudhury, Debalina Sengupta, Mahmoud M El-Halwagi, Nimir O Elbashir
Now, will the carbon formation in the first reactor affect the catalyst and the design of the process? Wouldn’t it lead to frequent shutdowns? The answer to these two important questions is that the know-how for handling “coking” reactions is already established and has been practiced extensively in the chemical industry. Chemical refineries generally employ an important unit, called a “coker” unit, that converts the residues of the Vacuum Distillation Unit (VDU) into pet-coke and light gases using catalyst and thermal cracking. This unit is known to produce around 400–500 tons per day(tpd) of solid coke in big refineries and utilize well-known fluidized bed concept for their operation. The first reactor will be operated under these conditions and, therefore, not many design challenges are expected. However, while segregating the coke formation and syngas formation reactions, an important problem of the DRM reaction is solved by alleviating its C/H ratio load on “actual” reformer unit, which operates on the product gases of the first reactor.
Reaction kinetics and coke forming propensities of Arabian mix asphalt vis-a-vis Arabian mix vacuum residue
Published in Petroleum Science and Technology, 2022
The rate constants estimated for various reaction pathways for the upgrading of AMA are shown in Table 3. It can be observed that the value of k3 at 475 °C is approximately nine times higher than corresponding value at 430 °C which indicates the dominance of condensation and polymerization reactions at 475 °C. The dominance of condensation and polymerization reactions were also substantiated by the experimental yield of petroleum coke (PC), wherein it was found that the yield of PC at 475 °C was about 20 wt% at 10 min of holding time, whereas at 430 °C, 445 °C and 460 °C, the yield of PC was approximately 2 wt %. The activation energy of reaction pathway leading to the formation of PC (257.94 kJ/mol) was more than that of activation energy of the reaction pathway showcasing LP formation (167.34 kJ/mol) as well as reaction pathway leading to the formation of GF (208.05 kJ/mol) as shown in Table 4. The activation energy for the formation of liquid product from Arabian mix asphalt (167.34 kJ/mol) was quite less than the reported activation energy (222 kJ/mol) (Phillips, Haidar, and Poon 1985) for the formation of distillates (liquid product) from Athabasca bitumen. Notably, the activation energy for the formation of coke from AMA (257.94 kJ/mol) was not found to be significantly different to the activation energy (262.12 kJ/mol) (Sawarkar, Pandit, and Joshi 2007) for the coke formation from AMVR. Thus, it can be concluded that the energy required for the cracking of AMA is only marginally higher than the corresponding vacuum residue, and therefore, AMA can be suitably treated in a coker unit.