Co-pyrolysis coking characteristics of nC12H26 and DHN/MeOH/EtOH/MF/DMF/H2O/H2/CO2/CO/N2 under supercritical condition

Abstract

The introduction of additives or carrier gases to change the physicochemical process of endothermic fuel in a regenerative cooling channel and then regulate the carbon deposition behavior is an important coking control method. In this work, the co-pyrolysis and coking behavior of several novel additives, such as alcohols, furans, flue gas, and syngas, is compared under the supercritical condition of n-dodecane (nC12H26) with the traditional hydrogen supply agent decalin (DHN) and inert nitrogen (N2) as the basis in a 304STS tube with an inner diameter of 2 mm. Results show that the addition of methanol (MeOH) / ethanol (EtOH) / 2-methylfuran (MF) / 2,5-dimethylfuran (DMF) promotes the pyrolysis of nC12H26 and shows a strong coking trend. The coking rate of carbon monoxide (CO) addition is higher than that of carbon dioxide (CO2) addition, and the system is prone to presenting an exothermic chemical effect. The addition of hydrogen (H2) does not contribute to the hydrogen source but leads to a high coking risk at a low blend ratio. Although water (H2O) and CO2 atmospheres exhibit coke inhibition potential, they weaken the heat absorption capacity of nC12H26. The co-pyrolysis of alcohols, furans, and hydrocarbon feedstock to CO needs to be controlled in a targeted manner, so that endothermic fuels have high heat sink and low coking tendency in regenerative cooling channels.