The issue of gasoline hydrogenation
Thread Content
I would like to ask the teachers: 1. In the gasoline hydrogenation unit, there is a bypass line for the cycle hydrogen before it passes through the air cooler after the reactor, and 60–70% of the cycle hydrogen flows through this bypass line; only a small portion of it is used for hydrogenation purification. What is the purpose of this bypass line? Is it to increase the amount of cycle hydrogen at the inlet of the compressor? Won’t the cyclohydrogen compressor be working for nothing then? 2. Which parameter, temperature or pressure, has a greater impact on the removal of S, N, and O during hydrorefining? Are there any relevant parameters or performance curves available? Thank you! ! ! ! ! !
This valve is used to maintain stable pressure in the compressor inlet buffer tank; its opening degree is generally not high. If the opening degree is increased, considering reducing the compressor’s load could help save energy. The relationship between hydrogenation depth and temperature is the most significant; for detailed information, one can refer to books such as those by Professor Chen on hydrogenation refining or by Academician Li Dadong on hydrogenation processing techniques
Are you referring to the backup emergency cooling hydrogen pipeline? ? By the way, are the hydrogen circulation machines you use turbines? If not, it’s best not to operate this pipeline. Removing nitrogen requires high pressure, while removing sulfur needs high temperature. In a newly installed facility, the pressure is usually fixed; only the temperature and the hydrogen-to-oil ratio (processing volume) can be controlled
Thank you, it’s not the line you mentioned
What is the device load? If the load is low, less cyclic hydrogen is used and the opening of the bypass line will be large.
1. This is the anti-surge line, which protects the circulating hydrogen compressor. 2. There is a very good linear relationship between the logarithm of the kinetic rate constants for various reactions and the reciprocal of the reaction temperature. ——Arrhenius 3. Pressure, specifically the hydrogen partial pressure, should be below 2–3 MPa; increasing the hydrogen partial pressure can significantly enhance desulfurization activity ； Above 3 MPa, the hydrogen partial pressure has little effect on directly evolved thiols, DBT, etc ； In the presence of nitrides, increasing the hydrogen partial pressure can accelerate their decomposition, releasing more active sites for hydrodesulfurization ； Above 3 MPa, it can accelerate the breaking of C-S bonds and increase the desulfurization rate ； Increasing the hydrogen partial pressure can raise the apparent activation energy of the hydrodenitration reaction ； (The activation energy for the hydrolysis reaction is much higher than that for the hydrogenation saturation reaction.) Increasing the hydrogen partial pressure can accelerate the rate of aromatic hydrogenation saturation, while it has an inhibitory effect on the rates of naphthenes’ dehydrogenation and ring-opening reactions. Aromatic hydrogenation requires high reaction pressures to proceed effectively, and increasing the hydrogen partial pressure can significantly enhance the degree of aromatic conversion ； Increasing the hydrogen partial pressure will inhibit isomerization and cracking reactions ； (As the aromaticity of the feedstock increases, the turning point at which hydrogen partial pressure shifts from a promoting to an inhibitory effect rises accordingly.) The presence of organic nitrides and ammonia increases the dependence of the cleavage reaction on hydrogen partial pressure.
It is an anti-surge line; it is generally not activated, but it comes online only when the circulating hydrogen compressor experiences surge.
1. What parts does the crossing span? Is it only the feed preheater? 2. It’s hard to say what the negative impacts will be; it depends on which components are predominant in the raw materials in order to develop a specific control plan. Trade-offs must be made, for example regarding the reaction temperature. Based on the principles of special cases, it can be concluded that increasing the hydrogen-to-oil ratio and raising the reaction pressure certainly enhances the effectiveness of desulfurization, nitrogen removal, and oxygen removal. However, when carrying out hydrogenation of gasoline, the vapor pressure of the product must be taken into account; therefore, it is not possible to provide a definite answer based on your question. :D
The anti-surge line ensures a minimum flow rate for the circulating hydrogen; an increase in the differential pressure across the surge valve indicates a problem that needs to be addressed promptly. If it cannot be resolved on-site, reducing the load or shutting down the system is necessary. Currently, surge valves are all controlled by organic CCS systems, along with surge curves； The refining efficiency is also influenced by factors such as operating temperature, hydrogen-to-oil ratio, hydrogen partial pressure, sulfur content, and catalyst properties; there is no fixed standard. Only catalyst manufacturers have the capability to create such curves, and this applies only when the properties of the raw materials are very stable. There is no absolute standard, and the corresponding requirements are to be provided by the catalyst manufacturer for this equipment.