【Ten Years of Great Progress in Chemical Engineering Technology】007-2023 Long-Term Operation Mechanism of New Fixed-Bed Residue Hydrogenation Systems

Thread Content

This post was last edited by Desert Fish on 2023-3-3 21:49. How to achieve long-term, efficient operation of fixed-bed residue hydrogenation units and improve their adaptability to low-quality feedstocks is a challenge that the petroleum refining industry urgently needs to address. The project \"Development and Application of a Long-Term Operation Mechanism for New Fixed-Bed Residue Hydrogenation Systems\", led by Sinopec (Dalian) Research Institute of Petroleum Chemistry Co., Ltd. (hereinafter referred to as Sinopec Dalian Institute), resulted in the creation of fixed-bed residue hydrogenation catalyst systems and corresponding grading technologies. It addressed the issues of pressure drop and metal tolerance that affect the long-term stable operation of industrial plants, bringing significant economic and social benefits to the enterprises that adopted these technologies. The project recently won the First Prize for Scientific and Technological Progress in 2022 from the China Petroleum and Chemical Industry Federation. 　　Yuan Shenghua, a leading expert at Sinopec Dalian Research Institute, said that currently, fixed-bed residue hydrogenation technology is the main approach used by refineries to process residue. Residue hydrogenation technology can, on the one hand, increase the degree of lightening of residue, and on the other hand, improve the quality of the residue after hydrogenation, thereby providing high-quality feed for downstream units. However, residue contains large amounts of complexly structured gums, asphaltenes, and metal-containing compounds (nickel and vanadium). During the hydroprocessing of residue, the catalyst loses its activity rapidly due to metal deposition and carbon deposition, which increases the risk of a rapid rise in pressure drop across the catalyst bed. This ultimately forces the plant to shut down for catalyst replacement. 　　To this end, the project team led by Yuan Shenghua, drawing on nearly 40 years of experience in the development and application of fixed-bed residue hydrogenation technology, has continuously pursued technological innovation and upgrades in response to the changing market demands and challenges associated with this technology. Progress has been made in catalyst preparation techniques, and the technical implementation has been successfully completed. 　　This project achieved 3 major technological innovations: first, it invented the S-Fitrap catalyst grading technology with smooth gradient transitions. This technology enables the concentrated deposits to be dispersed and deposited across multiple catalyst beds, increasing the metal tolerance of the catalyst system by over 18% and raising the porosity of the beds by about 10%. It helps to keep the pressure drop in the beds stable over the long term, which is beneficial for the steady operation of industrial plants. 　　Second, the technology of radially inverse distribution loading of active metals was invented, enabling the directional creation of an active site distribution with fewer sites on the outside and more on the inside. Thanks to the bimodal pore structure of the catalyst, the internal diffusion resistance of heavy oil macromolecules is reduced; metal impurities deposit within the particles, thereby increasing the catalyst’s metal capacity and its resistance to coking. This helps to address the issue of low overall utilization efficiency of the catalyst due to pore blockage, and makes better use of the internal pore space of the catalyst. This technology increases the metal content in the catalyst by over 15%. 　　Third, a desulfurization/residual carbon removal catalyst with strong resistance to metals/soot accumulation and a high porosity was developed. With a 10% higher porosity compared to similar reference materials, the catalyst can still maintain a low pressure drop even under dense packing conditions. Under the same conditions, the bed pressure drop is more than 30% lower than that of similar reference agents, and the overall impurity removal efficiency is about 5% higher. 　　According to Yuan Shenghua, this catalyst has been used in nearly 20 industrial installations at home and abroad, yielding significant economic benefits. With the use of this catalyst, the unit features a long operating cycle, good product quality, low system pressure drop, high metal tolerance, and a high processing load for residue oil; particularly, favorable results have been achieved in terms of pressure drop control. Against the backdrop of prolonged \"red ocean competition\" in China’s residue hydrogenation catalyst market, the successful development and implementation of this project have driven continuous improvement and advancement in the technology level of residue hydrogenation within China’s petroleum refining industry.