【Q&A Question 226】2018.08.20

Operating with a high hydrogen-to-oil ratio facilitates uniform mixing of oil and gas, allows for the removal of large amounts of reaction heat, ensures a balanced temperature in the catalyst reaction bed, and can reduce catalyst coking.

It helps to carry away the reaction heat and prevent excessive temperature rise

Advantages: An high hydrogen-to-oil ratio facilitates uniform mixing of oil and gas, allowing a large amount of reaction heat to be removed; this helps maintain a consistent temperature in the catalyst reaction bed and reduces catalyst coking. Disadvantages: The high hydrogen-to-oil ratio shortens the contact time between the feedstock and the catalyst, which is not favorable for the hydrogenation reaction. Additionally, more compressors are required, resulting in increased energy consumption.

In hydrogenation systems, a high hydrogen partial pressure is thermodynamically favorable for the hydrogenation reaction, and it also helps to suppress the condensation reactions that lead to carbon deposition. Maintaining a high hydrogen partial pressure is achieved through the circulation of large amounts of hydrogen. Therefore, the hydrogen-to-oil ratio used in the hydrogenation process **exceeds the value required for the chemical reaction; increasing this ratio can raise the hydrogen partial pressure. Favorable for mass transfer and the progress of hydrogenation reactions ； Furthermore, a large amount of hydrogen can also carry away the heat released during the hydrogenation process from within the reactor, which helps to maintain a stable bed temperature. However, there is also a limit to increasing the hydrogen-to-oil ratio; exceeding this limit reduces the residence time of the feedstock in the reactor, lowers the degree of hydrogenation, and increases power consumption, thereby raising operating costs. The hydrogen-to-oil ratio should not be too low either; a too-low ratio will result in reduced hydrogenation depth and an increased rate of catalyst carbon deposition ； At the same time, the flow of gas and liquid within the heat exchanger and heating tubes becomes unstable, resulting in pressure and temperature fluctuations within the system. Therefore, the appropriate hydrogen-to-oil ratio must be selected based on the specific operating conditions.

It helps to protect the catalyst and yields a better refining effect

In hydrogenation systems, a high hydrogen partial pressure is thermodynamically favorable for the hydrogenation reaction, and it also helps to suppress the condensation reactions that lead to carbon deposition. Maintaining a high hydrogen partial pressure is achieved through the circulation of large amounts of hydrogen. Therefore, the hydrogen-to-oil ratio used in the hydrogenation process **exceeds the value required for the chemical reaction; increasing this ratio can raise the hydrogen partial pressure. Favorable for mass transfer and the progress of hydrogenation reactions ； Furthermore, a large amount of hydrogen can also carry away the heat released during the hydrogenation process from within the reactor, which helps to maintain a stable bed temperature.

Operating with a high hydrogen-to-oil ratio facilitates uniform mixing of oil and gas, allows for the removal of large amounts of reaction heat, ensures a balanced temperature in the catalyst reaction bed, and can reduce catalyst coking.

1. Increase the hydrogen partial pressure in the reactor to enhance the reaction depth; 2. Provide a reducing environment to prevent coking; 3. Facilitate heat removal from the reaction bed. 4. Reduce the residence time of the reactants. 5. Improve the physicochemical effects of hydrogen on the raw materials

Operating with a high hydrogen-to-oil ratio facilitates uniform mixing of oil and gas, allows for the removal of large amounts of reaction heat, ensures a balanced temperature in the catalyst reaction bed, and can reduce catalyst coking.