Hydrogen-to-oil volume ratio of the hydrogenation unit

1. It refers to the ratio of the amount of hydrogen in the recycled hydrogen to the volume of the feed oil; this naturally includes the amount of hydrogen used for quenching. 2. The hydrogen-to-oil ratio is generally adjusted using the recycled hydrogen compressor, and it is related both to the amount of hydrogen that is recycled and to the purity of the hydrogen. It cannot be determined solely based on the amount of hydrogen recycled. The purity of the hydrogen depends on the amount of fresh hydrogen added and the amount of hydrogen discharged from the system. Only when the purity of the hydrogen is constant can the hydrogen-to-oil ratio be adjusted by changing the flow rate of the recycled hydrogen. 3. An excessively low hydrogen-to-oil ratio not only reduces the reaction rate and hinders the progress of hydrogenation reactions, but it also leads to increased carbon deposition on the catalyst, reducing its service life. Additionally, heat cannot be removed in a timely manner, posing a safety risk

The volume hydrogen-to-oil ratio, which is the ratio of the volumetric flow rate of hydrogen under standard conditions to the volumetric flow rate of the feed oil, is commonly used in industrial plants. The hydrogen volume is the product of the circulation gas flow rate and the hydrogen concentration in the circulation gas. The hydrogen-to-oil ratio in the refining reactor = the circulation hydrogen flow rate at the inlet of the refining reactor / the volume of fresh feed. The hydrogen-to-oil ratio in the cracking reactor = (the circulation hydrogen flow rate at the inlet of the refining reactor + the circulation hydrogen flow rate at the inlet of the cracking reactor + the cold hydrogen flow rate at the inlet of the refining reactor) / (the volume of fresh feed + the volume of recycled oil). The hydrogen-to-oil ratio refers to the standard volume of circulation hydrogen required per unit volume of feed per hour; it is also an important parameter that affects the hydrocracking process, influencing both the reaction kinetics and the lifespan of the catalysts. An excessively high hydrogen-to-oil ratio increases the operating costs and equipment investment for the facility.

Hydrogen-to-oil ratio: In addition to protecting the catalyst, the large amount of hydrogen flowing through the reactor helps to carry away the heat generated by the reaction, thereby maintaining a uniform temperature within the reactor. Moreover, since hydrogenation is carried out using a trickle flow method, the large amount of hydrogen mixes with the feedstock, resulting in a more even distribution of the feedstock as it passes through the catalyst bed. Methods to increase the hydrogen-to-oil ratio: (1) Increase pressure; (2) Increase the compressor displacement. Raising the hydrogen-to-oil ratio is beneficial for the hydrogenation reaction, as it increases the molecular ratio of hydrogen to the feedstock. An increased concentration of reactant molecules facilitates the reaction to proceed toward the formation of products, thereby improving product quality and reducing catalyst coking. However, if the hydrogen-to-oil ratio is too high, the contact time between the feedstock and the catalyst is reduced, which is detrimental to the hydrogenation reaction. This leads to a decrease in the degree of hydrogenation and an increase in system pressure drop, both of which are unfavorable for the production process. Therefore, the hydrogen-to-oil ratio used in hydrogenation must be chosen appropriately, taking various factors into consideration.

It refers to the ratio of the amount of hydrogen in the recycled hydrogen to the volume of the feed oil. Generally, the amount of hydrogen used for quenching is not included in this calculation

According to the definition provided in ＜Hydroprocessing Processes and Engineering＜ compiled by Li Dadong, the hydrogen-to-oil ratio is the ratio of the gas flow rate entering the reactor to the amount of feed oil per unit of time. The gas entering the reactor consists of fresh hydrogen and recycled hydrogen; typically, the flow rate of recycled hydrogen is more than three times higher than that of fresh hydrogen. The flow rate of recycled hydrogen roughly indicates the value of the hydrogen-to-oil ratio in the reaction

The volume ratio of the recycle gas at the reactor inlet (including the supplemental hydrogen) to the feed oil is called the gas-to-oil ratio, while the volume ratio of pure hydrogen in the recycle hydrogen to the feed oil is called the hydrogen-to-oil ratio. The volume of the gas is taken as its volume under standard conditions, and the volume of the feed oil is its volume at 20 degrees Celsius. A higher hydrogen-to-oil ratio can provide sufficient hydrogen for the hydrogenation reaction, maintain the hydrogen partial pressure in the reactor, ensure a uniform distribution of hydrogen throughout the catalyst bed, and at the same time protect the catalyst by reducing carbon deposition. However, an excessively high hydrogen-to-oil ratio not only increases energy consumption but also reduces the contact time between the feedstock and the catalyst, which is detrimental to the hydrogenation reaction and results in a lower degree of hydrogenation. Therefore, the hydrogen-to-oil ratio must be chosen appropriately.

The ratio of the amount of hydrogen passing through a unit volume of catalyst in the reactor per unit time to the feed rate is known as the hydrogen-to-oil ratio. This ratio must take into account the cold hydrogen as well. Controlling the hydrogen-to-oil volume ratio is primarily achieved by regulating the flow rate of recycled hydrogen. An insufficient hydrogen-to-oil ratio affects the hydrogen partial pressure, resulting in inadequate reaction depth and poor hydrogenation efficiency.

Role of the hydrogen-to-oil ratio: Increase the hydrogen concentration, promote the reaction to proceed in the desired direction, and improve the refining efficiency. It facilitates liquid distribution and prevents coking. Prevent coking of the furnace tubes. It can carry away the heat generated during the reaction process.

Do you need the concept or the specific calculation formula?； When evaluating the hydrogen-to-oil ratio, you also need to take into account factors such as hydrogen partial pressure, hydrogen purity, space velocity, bed temperature, bromine value, Dubois value, and sulfur content. The data for these factors was already available at the time your plant was designed

1. How is the hydrogen-to-oil volume ratio in the hydrogenation unit calculated? Is it necessary to take into account the amount of quench hydrogen in this calculation? The hydrogen-to-oil ratio is defined at a specific location, usually at the reactor inlet; when using the amount of recycled hydrogen, it is necessary to take into account the amount of cold hydrogen as well. 2. How to control the hydrogen-to-oil volume ratio of the device? Generally, the speed of the circulating hydrogen compressor is adjusted to regulate the hydrogen-to-oil ratio. What consequences will occur if the volume ratio of hydrogen to oil does not meet the specified standards? The catalyst is unlucky – its lifespan is affected

If the circulating hydrogen volume is too high, it will result in too short a reaction contact time and the removal of a large amount of heat, increasing energy consumption; if it is too low, it can easily cause coking of the catalyst!

Generally, only the hydrogen-to-oil ratio at the reactor inlet is calculated!