Application of suspended-bed hydrogenation technology in refinery retrofitting
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Suspension bed hydrogenation technology: This involves the hydrothermal cracking of low-quality residue oil in a suspension bed reactor, using liquid-phase catalysts. Milder reaction conditions are employed to cause partial cracking of the residue oil, thereby removing most of the sulfur, nitrogen, and heavy metals; these substances then remain concentrated in the heavier fractions. Two process combinations: 1. Combined with catalytic cracking, where the hydrocracking products are separated; the light fractions are fed into hydrorefining to produce gasoline and diesel, while the heavy fractions are subjected to solvent deasphalting before being used as feedstock for catalysis. 2. The separated recombinant fraction is used directly as coking feed. Effects: 1. The light oil yield across the entire plant increases significantly, enhancing economic benefits. The light oil yield increased by about 5% compared to the original process. 2. After hydrogenation of the catalytic feedstock, its quality improves significantly, which allows for reduced catalytic energy consumption and an improved product distribution. Especially in chemical catalytic units, this approach enables maximum production of olefins, thereby enhancing the economic efficiency of such units. 3. The coke yield can be reduced by 5–10%, allowing the production of low-sulfur petroleum coke. Coking wax oil can be used directly as a catalytic feedstock without hydrogenation. 4. Improve sulfur recovery rates and reduce emissions of polluted gases. 5. Without changing the subsequent equipment, the crude oil processing capacity of the entire facility can be increased by 30%. It is an effective method for refineries to process low-quality raw materials, improve product quality, adjust the product structure, reduce environmental pollution, and enhance economic efficiency.
What catalyst is used in a suspended-bed reactor?
I heard President Xu talk about this technology; it must be pretty good!
Liquid-phase catalyst, containing molybdenum metal. It has high pyrolysis activity; it undergoes pyrolysis under hydrogen-rich conditions, while coking must be suppressed. Slurry beds use solid catalysts, such as iron ore powder, and there are also those based on coal and oil co-processing, with a very high conversion rate of coal into oil.
I’m not sure if solid catalysts in suspended beds are useful?
Initially, solid catalysts were used, but industrial tests revealed that mixing solid catalysts with medium oil, along with the subsequent separation of the hydrogenated products, posed engineering challenges; therefore, liquid-phase catalysts were adopted instead.
Hey, suspended bed technology has been under research for decades; it’s already industrialized abroad, so why isn’t there any progress in China?
In China, China University of Petroleum has also been conducting research for several decades, and numerous pilot-scale evaluations have been carried out, including those related to kerosene blending. We want to promote this technology, and we will first make breakthroughs in hydrogen pretreatment prior to catalytic or delayed coking feedstocks.
Kerosene co-processing in a suspended-bed hydrogenation process: 75% residue + 25% coal powder; the suspended-bed reactor operates at a pressure of 8 MPa and at a temperature of 420–430°C. After solvent deasphalting, 10% is gas along with losses, 80% is obtained as liquid product, and 10% remains as semi-coke. Both pressure and temperature are relatively mild. It is a very promising technology.
Oh, I was wondering if this technology was developed in collaboration with a petroleum university or independently? Is it from the Fuyan Research Institute?
Professor Que has been studying the technology from the Petroleum University for over 20 years; currently, Professor Deng is working on it. The project is carried out by CNPC, and a pilot industrial plant with an annual capacity of 50,000 tons was built in Fushun, with good results. However, a solid powder catalyst is used; the amount of powder catalyst required is small, and it is difficult to disperse it in oil in industrial plants. Moreover, it is hard to separate the solid particles from the product, which is why no large-scale facilities have been built. Currently, work is being done on liquid-phase catalysts and oil-coal co-processing. The process involves catalytic thermal cracking under hydrogen atmosphere, product separation, and online hydrogenation refining, with the goal of producing as many light liquid products as possible (primarily diesel). At present, we apply the suspended-bed hydrogenation technology to the pretreatment of raw materials in existing refineries, that is, pre-hydrogenation. By reducing reaction conditions such as pressure and temperature, it enables the conversion from directly producing qualified products to carrying out raw material pretreatment, thereby providing materials for catalysis or coking. We are working on tasks such as scheme design, laboratory verification, and technical-economic preliminary assessment.