Hydrocracking start-up method

Abstract

The invention discloses a hydrocracking start-up method, which includes the following contents: firstly, introducing low-nitrogen start-up oil, hydrogen and vulcanizing agent into the hydrocracking unit, and then performing constant temperature vulcanization on the hydrocracking catalyst under the condition of 220-260°C, After the hydrogen sulfide content in the circulating hydrogen reaches 3000-5000ppm, reduce the adding rate of the sulfiding agent and increase the bed temperature of the hydrocracking catalyst, and increase the adding rate of the sulfiding agent when the bed temperature of the hydrocracking catalyst reaches 310°C-330°C , after continuing the constant temperature vulcanization, raise the temperature to 380°C-390°C and feed the raw oil for reaction, wherein the hydrocracking catalyst contains 0.3%-4% nitrogen element by weight percentage, and the nitrogen element comes from low molecular nitrogen compounds and strongly basic cyclic nitrides. The method has the advantages of short time required for starting up, switching raw materials and entering a stable production state, avoiding the consumption of passivating agent during the starting process and the potential danger in the ammonia injection process, not only saving energy consumption, but also reducing the impact of passivating agent on the environment Pollution and harm to the human body.

Description

technical field [0001] The invention relates to a hydrocracking start-up method, in particular to a hydrocracking start-up process method without external injection of a passivating agent. Background technique [0002] The hydrocracking process is under the action of hydrogen, high temperature, high pressure and catalysts to hydrodesulfurize, hydrodenitrogenate, polycyclic aromatic hydrocarbons, hydrosaturation and ring-opening cracking of heavy distillate oils (VGO, CGO, DAO). The process of conversion into target products such as light oil and middle distillates. The hydrocracking catalysts currently produced in domestic industry are basically oxidative. New catalysts or regenerated catalysts produced in industry contain active metal components (Mo, Ni, Co, W) in the oxidation state (MoO 3 , NiO, CoO, WO 3 ) exists in the form of The practice of basic research and industrial application shows that most of the active metal components of hydrogenation catalysts have high...

AI Technical Summary

Problems solved by technology

[0007] Passivators such as anhydrous liquid ammonia injected outside the device can make the start-up process smooth and safe, but it needs to be transported by a pressure pump, which not only increases the one-time investment of the device, but also wastes the floor area. Equipment that is intermittently opened often breaks down and affects the progress of the start-up. At the same time, the danger of anhydrous liquid ammonia has been described above, and its controllability is self-evident; if the cracking catalyst is not passivated outside the device If the catalyst is not injected, the stability and safety of the start-up process will inevitably be reduced, and the vulcanization process will also be shortened or terminated, which will have a great impact on the activity of the catalyst, which may affect the long-term stable operation of the catalyst.

[0008] Both CN101492613A and CN101492607A disclose the start-up method of the hydrocracking process, which has certain safety and convenience, but still belongs to the method of forced injection of ammonia outside the device to inject a certain passivating agent into the reaction system to inhibit the activity of the cracking agent. There are bound to be disadvantages of injecting ammonia in the above-mentioned prior art, which will bring certain hidden dangers and harm

However, there are still other liquid components that are additionally introduced, and the control control is difficult to achieve, and the start-up process takes a long time

[0012] CN102284299A and CN1602999A relate to a method of hydrogenation catalyst presulfurization outside the hydrogenation reactor-activation in the hydrogenation reactor, which completes the deactivation process of the sulfidation agent of the catalyst under specific working conditions outside the reactor, but the introduced The gas contains catalyst "poisons" and is relatively simple, which cannot completely complete the passivation process of the catalyst. In addition, it is difficult to ensure the adsorption and excess of the passivation gas during the transportation and vulcanization process. insufficient

[0013] CN102921441A has introduced a kind of preparation method of tungsten phosphide catalyst, it passes nitrogen flow to passivate the catalyst in the preparation process, although the effect of passivation can be played to a certain extent, but the passivation effect of inert gas is very poor , cannot be applied to the hydrocracking process

[0014] CN104593051A and CN104593050A disclose a method for starting a vulcanized hydrogenation catalyst. The oil film generated by the added chemical substance is used to passivate the exothermic process of the vulcanized catalyst, although it can completely solve the heat control problem of the concentrated release of sulfur during the vulcanization process , but it cannot be applied in the field of hydrocracking, the oil film formed by it will react or decompose during hydrocracking, and cannot play the role of passivation

Although the process of preparing the presulfurized catalyst outside the device is convenient and feasible, and the energy consumption is reduced, the passivation process still has a certain inhibitory effect on the heat release of the presulfurized catalyst outside the device, so it cannot be applied in the field of hydrocracking

[0016] CN104342200A discloses a method for selective hydrogenation of reformed oil, the core of which is to use some "poisons" to passivate the active metals in the catalyst. Although the effect is remarkable, it is not suitable for the hydrocracking process. For molecular sieves passivation process

[0017] The literature "Research on the Presulfidation and Passivation Process of Hydrogenation Catalysts" introduces the reaction mechanism of the passivation process of presulfided hydrogenation catalysts in detail. In the hydrogenation process with cracking reaction, it is different from the passivation mechanism of our conventional hydrocracking catalyst, so it cannot be applied to the hydrocracking process

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