On the hydrogen-to-oil ratio in diesel hydrogenation
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When calculating the hydrogen-to-oil ratio in a diesel hydrotreating unit, is the volume of hydrogen calculated based on its standard volume? So how is the volume of diesel calculated? How is the hydrogen-to-oil ratio in diesel hydrogenation typically determined? Is it usually based on empirical values? When calculating the hydrogen-to-oil ratio, quench hydrogen shouldn’t be included, right? So does quench hydrogen actually participate in the reaction?
Hydrogen is calculated based on standard volume, while diesel is calculated based on m3 volume. Quench hydrogen is not included, but it participates in the reaction just like recycled hydrogen. The hydrogen-to-oil ratio is generally determined by the design institute based on the raw materials and products, etc.
Could we know approximately how much cold hydrogen will be involved in the reaction? Since cold hydrogen is involved in the reaction, what is then the significance of the hydrogen-to-oil ratio? Can it be understood that, ignoring energy consumption and the capacity of the device, the higher the hydrogen-to-oil ratio, the better?
If energy consumption is not a concern, the higher the hydrogen-to-oil ratio, the better. A higher hydrogen-to-oil ratio results in an increased hydrogen partial pressure; with a constant feed rate, this leads to a larger volume of recycled hydrogen, which is beneficial for the hydrogenation reaction. Moreover, a larger volume of recycled hydrogen helps to protect the catalyst
The H2/HC ratio is typically expressed in two ways: either as a volume ratio of hydrogen to oil, or as a molar ratio of hydrogen to oil. Calculate using the following formulas: Hydrogen-to-oil volume ratio = Volume flow rate of mixed hydrogen under standard conditions / Volume flow rate of feed oil; Hydrogen-to-oil molar ratio = Molar flow rate of mixed hydrogen / Molar flow rate of feed oil. During operation with a gas recycling system, since the amount of gas that can be recycled is a function of the compression ratio, the volume of recycled gas will gradually decrease as the system pressure drop increases, especially when a centrifugal compressor is used. Under these conditions, a reduction in the circulation gas volume is still permissible as long as the calculated IH2/HC ratio is not lower than the design value. However, if it is too low, the catalyst must be regenerated and screened to reduce the system pressure drop. The calculation of the hydrogen-to-oil ratio is based on standard volume for hydrogen, and on m3 volume for diesel (both under standard conditions). Quenched hydrogen is not included in the calculations, as its amount is generally small.
Refined cold hydrogen is generally not taken into account; cracked hydrogen is
The volume of hydrogen here is calculated based on its actual volume; it’s whatever the flow meter indicates； The volume of diesel is also based on the values in the table, but the average flow rate is calculated by dividing the cumulative value by time ； Our hydrogen-to-oil ratio is >500:1 ； Since the flow meter for circulating hydrogen is located at the inlet of the circulator, it already takes into account the amount of cold hydrogen ； Cold hydrogen participates in the reaction.
An excessively high hydrogen-to-oil ratio reduces the contact time between the feedstock and the catalyst, which in turn is unfavorable for the hydrogenation reaction; as a result, the degree of hydrogenation decreases and the system pressure drop increases.
In our case, it is calculated by multiplying the amount of circulating hydrogen at the inlet of the cyclic hydrogen compressor by the hydrogen purity, adding the amount of new hydrogen added, which constitutes the hydrogen volume, and then dividing that by the volume of oil. . .