Abstract
Heat integration is an important approach in reducing plant size and decreasing operating costs. In refinery/petrochemical fluid catalytic cracking(FCC), the cooling of the catalyst as it undergoes endothermic cracking reactions is a primary mechanism for activity loss. This talk will describes a new approach that co-mixes a heat generating material(HGM) with the standard equilibrium FCC catalyst in order to reduce activity loss due to cooling. The HGM produces heat from redox reactions that occur on in both the reducing FCC reactor and the oxidizing FCC regenerator. By co-mixing HGM with FCC catalyst of similar size and density, improvements in the reactor temperature profile were observed, which corresponded to improved conversion and selectivity.
Heat transfer occurs between the HGM, which undergoes exothermic reactions, and the FCC catalyst, which undergoes endothermic cracking. The HGM contains a Zeolytic solid acid for cracking hydrocarbons, and reducible metal oxides, such as copper or cobalt, which reacts with the cracked product stream to generate heat. The reduced metal cost cider on the HGM is then regenerated in an oxidizing atmosphere with additional heat release. This process avoids overheating, which can cause overcracking and accelerated coke formation. Additionally, the oxide form of the HGM reacts with hydrogen produced from the endothermic cracking process to produce water. By reducing the hydrogen concentration in the cracked product gas, the equilibrium shifts to promote hydrocarbon cracking to the desired light olefins.