Investigation of the effect of presulphidation on coke deposition on 25Cr‐35Ni alloy during ethane steam cracking

Abstract

The process of hydrocarbons cracking is carried out in the presence of heatresistant alloys Fe-Ni-Cr, which HP40 alloy (25Cr-35Ni) has the most applications among olefin plants. Since these alloys naturally tend to form coke, the industry has always tried to reduce the coke formation by reducing the catalytic properties of the coils. In this research, the effect of dimethyl disulphide (DMDS) concentration (200-900 ppm) on the HP40 alloy of industrial coils at the presulphidation stage is evaluated. In the presulphidation stage, the alloy surface is in contact with sulphur in the absence of hydrocarbons, and this affects the amount of coke formation in the cracking process. Also, the surface composition and morphology of coke are identified using EDX and SEM analysis. These results showed that at the 500 ppm concentration of DMDS, coke deposition is minimized. Additionally, our findings indicated that coke morphology has not changed under different presulphidation conditions, and coke is still a filament type, but the size of the filaments has changed. Moreover, the study of HP40 composition in both preoxidized and presulphide stages shows that presulphidation reduces the amount of Fe and Ni in the coke layer significantly.

Preoxidation Film and Its Anticoking Behavior on an Optimized HP40Nb Alloy with Al, Zr, Y Addition

“…Al 2 O 3 oxide layer is formed by preoxidation in low oxygen pressure. The Al 2 O 3 oxide layer can prevent Fe and Ni elements from diffusing outward, colliding with C and H free radicals, and reducing surface catalytic coking. − The cracking depth and conversion rate of feedstock are reduced, the final reaction rate is reduced, and the amount of small molecule hydrocarbons and unsaturated hydrocarbons is reduced.…”

Adsorptive Desulfurization of Condensate Contains Aromatic Compounds Using a Commercial Molecular Sieve

“…Sulfur compounds, particularly sulfur oxides (SOx), cause various environmental hazards and industrial damage. In the petroleum industries, sulfur compounds cause pipeline corrosion, jeopardizing distribution networks, reducing the oil and gas quality, and poisoning or deactivating the downstream catalysts. − Thus, there has been a high demand for producing sulfur-free petroleum fuels and intermediate products recently . Moreover, stringent environmental rules and regulations have been imposed on the allowable sulfur concentration of transportation fuels to minimize the adverse effects of sulfur emissions into the air. , To remove sulfur contained in petroleum fractions, numerous methods such as hydrodesulfurization, pervaporation, adsorption, biodesulfurization, extraction, and oxidation have been used. , Among these methods, hydrodesulfurization (HDS) has been the most widely used technology for removing sulfur compounds in refineries in the past few decades. , HDS is a catalytic process that involves a reaction with hydrogen and converts organosulfur compounds to H 2 S and sulfur-free compounds.…”

“…In the petroleum industries, sulfur compounds cause pipeline corrosion, jeopardizing distribution networks, reducing the oil and gas quality, and poisoning or deactivating the downstream catalysts. 1 − 3 Thus, there has been a high demand for producing sulfur-free petroleum fuels and intermediate products recently. 4 Moreover, stringent environmental rules and regulations have been imposed on the allowable sulfur concentration of transportation fuels to minimize the adverse effects of sulfur emissions into the air.…”