CN114437787B

CN114437787B - Hydrocracking method

Info

Publication number: CN114437787B
Application number: CN202011116018.XA
Authority: CN
Inventors: 王仲义; 崔哲; 彭冲; 吴子明; 曹正凯
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2020-10-19
Filing date: 2020-10-19
Publication date: 2023-05-26
Anticipated expiration: 2040-10-19
Also published as: CN114437787A

Abstract

The invention discloses a hydrocracking method, which comprises a hydrocracking reaction zone and a hydrocracking reaction zone, wherein the hydrocracking reaction zone is filled with a high-activity hydrocracking catalyst and a low-activity hydrocracking catalyst in sequence along the material direction, the reaction temperature of the high-activity hydrocracking catalyst is improved to control the product quality when the nitrogen content of effluent of the hydrocracking reaction zone is higher than 20 mug/g, and the temperature of the high-activity hydrocracking catalyst reaction zone and the temperature of the low-activity hydrocracking catalyst reaction zone are synchronously adjusted to control the product quality when the average reaction temperature of the high-activity hydrocracking catalyst and the reaction temperature of the low-activity hydrocracking catalyst differ by 0-3.5 ℃. The method can ensure the long-period operation of the device in emergency or processing of poor raw materials and ensure the yield increase of heavy naphtha.

Description

Hydrocracking method

Technical Field

The invention relates to a hydrocracking method, in particular to a hydrocracking method with strong raw material adaptability and long-period running.

Background

The core of the hydrocracking technology is a catalyst, which mainly consists of two basic parts of a carrier and metal, and is a bifunctional catalyst. Molecular sieves are a characteristic constituent structure of the carrier part and are also an indispensable component of a hydrocracking catalyst with high cracking activity. In the hydrocracking feeding, the requirements on the nitride are higher in the indexes of each requirement control of the raw materials, because the nitride not only affects the stability of the molecular sieve catalyst, but also has great influence on the activity, especially the alkaline nitride has strong inhibition effect on the cracking performance of the catalyst, and the nitride is unstable and easy to condense and coke to cause the activity loss of the catalyst, so the method is the first focus in each index.

Just because organic nitrides have a great influence on acidic catalysts, nitrogen is one of the most important factors affecting the reaction effect in hydrocracking processes. The conventional measures are that the original nitrogen is removed by the pretreatment reaction section and then enters the cracking reaction section for cracking, so that the condensation coking rate of the catalyst in the cracking section is reduced, and the service life of the catalyst is prolonged, and therefore, the control of the nitrogen content of refined oil is an essential and indispensable important link in the hydrocracking technology.

CN201310523055.6 discloses a hydrocracking method, the high nitrogen raw oil and hydrogen-rich gas are mixed and then heated to enter a first reaction zone, a hydrofining reaction and a hydrocracking reaction are carried out, after cooling and oil-gas separation, the reactant flow is fractionated to obtain light naphtha, heavy naphtha and tail oil fraction, wherein the tail oil fraction is pressurized and then mixed with recycle hydrogen to enter a second reaction zone for hydrocracking reaction. The invention can fully convert the tail oil fraction difficult to convert into the naphtha fraction under the conditions of high airspeed and low severity, thereby improving the selectivity of heavy naphtha.

CN201310540361.0 discloses a poor quality feedstock hydrocracking process. Firstly, carrying out a first-stage hydrofining reaction on the inferior raw material, wherein a gas-liquid parallel flow and a countercurrent flow are adopted in the first stage; the generated oil obtained in the first section enters a second refining section to carry out deep denitrification and aromatic saturation reaction, and the second section adopts a gas-liquid parallel flow process; and mixing the effluent of the second stage reaction with hydrogen, and then entering a third stage reaction zone to carry out hydrocracking reaction. The method can carry out hydrotreatment on nitrogen-containing impurities in the inferior raw material under a mild condition, so that the nitrogen-containing impurities can meet the hydrocracking feeding requirement, and the raw material source of hydrocracking is widened.

CN201811264082.5 discloses a hydrocracking method for high dry point high nitrogen raw oil. Under the condition of a hydrofining process, mixing high-nitrogen high-dry-point raw oil with hydrogen, entering a reactor with graded hydrofining catalyst for hydrofining reaction, and then entering a hydrocracking reactor for hydrocracking reaction, wherein the hydrocracking reactor is filled with hydrocracking catalyst; the hydrocracking reaction effluent enters a separation system, and one or more of gas, naphtha, aviation kerosene and diesel oil and tail oil are obtained through separation. The method can effectively treat the high-dry-point high-nitrogen raw oil, and has the advantages of simple flow, easy operation and the like.

CN201210408333.9 discloses a combined hydrocracking process for processing poor quality feedstock. Pretreating high-nitrogen raw oil by adopting a countercurrent hydrogenation process, and pretreating conventional raw oil by adopting a cocurrent hydrogenation process; countercurrent hydrogenation to obtain liquid and the countercurrent hydrogenation effluent to enter a hydrocracking reactor for reaction; and mixing the hydrocracking effluent with the countercurrent hydrogenation to obtain gas, performing gas-liquid separation, and fractionating the obtained liquid product to obtain the hydrocracking product. Because the liquid obtained by pretreatment of the high-nitrogen raw oil is basically free of ammonia, the liquid is mixed with the conventional raw material hydrogenation effluent for hydrocracking, the influence of ammonia partial pressure on hydrocracking is reduced, and the running period of the device is prolonged.

In the prior art, nitrogen elements in raw materials are effectively removed, so that the raw materials meet the requirement of downstream feeding, and fluctuation in the production process and unexpected conditions are not fully considered, so that the operation period of a hydrogenation device is reduced.

Disclosure of Invention

Aiming at the defects existing in the prior art, the invention discloses a hydrocracking method, which can offset the influence of the too high content of refined oil nitrogen on the performance of a cracking section catalyst, so that the device has stronger capability of coping with emergency or processing inferior raw materials, and is beneficial to ensuring the yield increase of heavy naphtha.

A hydrocracking method comprises a hydrocracking reaction zone and a hydrocracking reaction zone, wherein the hydrocracking reaction zone is sequentially filled with a high-activity hydrocracking catalyst and a low-activity hydrocracking catalyst along the material direction, the reaction temperature of the high-activity hydrocracking catalyst is improved to control the product quality when the nitrogen content of effluent of the hydrocracking reaction zone is higher than 20 mug/g, preferably 30-50 mug/g, and the average reaction temperature of the high-activity hydrocracking catalyst and the average reaction temperature of the low-activity hydrocracking catalyst are synchronously adjusted to control the product quality when the average reaction temperature of the high-activity hydrocracking catalyst and the average reaction temperature of the low-activity hydrocracking catalyst are different by 0-3.5 ℃, preferably 0-2.5 ℃.

In the method, the hydrogenation pretreatment reaction zone is filled with a hydrofining catalyst, and the hydrofining catalyst comprises a carrier and a loaded hydrogenation metal. Typically comprising, based on the weight of the catalyst, a metal component of group VIB of the periodic Table of the elements, such as tungsten and/or molybdenum, in the form of oxides, in the range of 10% to 35%, preferably 15% to 30%; the group VIII metal, such as nickel and/or cobalt, is 1% to 7%, preferably 1.5% to 6% by oxide. The carrier is inorganic refractory oxide, and is generally selected from alumina, amorphous silica-alumina, silica, titania and the like. Wherein the conventional hydrocracking pretreatment catalyst can be selected from various existing commercial catalysts, such as hydrofining catalysts of FF-16, FF-26, FF-36, FF-46 and the like developed by the Fushun petrochemical institute (FRIPP); can also be prepared as desired according to common general knowledge in the art.

In the above method, the operation conditions of the hydrotreatment reaction zone are as follows: the operating pressure is 10.0-16.0 MPa, the hydrogen-oil volume ratio is 500:1-1000:1, and the volume airspeed is 0.2-6.0 h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the Preferably, the operation pressure is 12.0-15.0 MPa, and the hydrogen-oil volume ratio is 600:1-1000:1.

In the above method, the conventionally used raw oil is wax oil or diesel oil component, preferably wax oil, the final distillation point of the wax oil is generally 450-540 ℃, preferably 480-530 ℃ and the density is generally 0.93g/cm ³ Hereinafter, it is preferably 0.92g/cm ³ In the following, the nitrogen content is generally not more than 0.12% by weight, preferably not more than 0.11% by weight, and the sulfur content is not particularly limited. The wax oil can be various straight run or secondary processed wax oil obtained by processing naphthenic base crude oil, intermediate base crude oil or paraffin base crude oil, and the like, or can be an oil product obtained by mixing the various wax oils, and any liquid phase oil product which is suitable for being used as a raw material of a hydrocracking device is in the application range. The nitrogen content of the refined oil after the process passes through the hydrogenation pretreatment is generally less than 20 mug/g.

In the method, the high-activity hydrocracking catalyst and the low-activity hydrocracking catalyst are sequentially filled in the hydrocracking reaction zone along the material direction, wherein the filling volume ratio of the high-activity hydrocracking catalyst to the low-activity hydrocracking catalyst is 1:1.5-1:3.5, preferably 1:2-1:3, and the molecular sieve mass content of the high-activity hydrocracking catalyst is 1.2-2.2 times, preferably 1.5-2 times of that of the low-activity hydrocracking catalyst.

In the above method, the hydrocracking catalyst filled in the hydrocracking reaction zone contains hydrogenation active metal, acidic molecular sieve component and alumina carrier, and the hydrocracking catalyst can be selected from various existing commercial catalysts or can be prepared according to the prior art.

In the method, the high-activity hydrocracking catalyst contains 10% -30%, preferably 15% -25%, of active metal oxide and more than 50% of molecular sieve by weight, wherein the active metal comprises one or more of Wo, mo, co, ni, and the molecular sieve comprises but is not limited to Y-type or USY molecular sieve.

Hydrocracking catalysts such as FC-24, FC-46, FC-52 developed by the Fu petrochemical institute (FRIPP); can also be prepared as desired according to common general knowledge in the art.

In the method, the low-activity hydrocracking catalyst contains 15-40% by weight, preferably 18-35% by weight of active metal oxide and 20-40% by weight of molecular sieve, wherein the active metal comprises one or more of Wo, mo, co, ni, and the molecular sieve comprises but is not limited to Y-type or USY molecular sieve. Hydrocracking catalysts such as FC-12, FC-32, FC-76 developed by the pacifying petrochemical institute (FRIPP); can also be prepared as desired according to common general knowledge in the art.

In the method, when the nitrogen content of the effluent of the hydrogenation pretreatment reaction zone is less than 20 mug/g, preferably less than 15%mug/g, the average reaction temperature of the high-activity hydrocracking catalyst bed layer of the hydrocracking reaction zone is 350-360 ℃, preferably 350-355 ℃; the average reaction temperature of the low-activity hydrocracking catalyst bed layer is 362-372 ℃, preferably 365-370 ℃.

In the method, the hydrocracking reaction condition is that the operating pressure is 10.0-16.0 MPa, the volume ratio of hydrogen to oil is 600:1-1200:1, and the volume airspeed is 0.1-5.0 h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the Preferably, the operation pressure is 12.0-15.0 MPa, and the hydrogen-oil volume ratio is 700:1-1000:1.

In the method, the control of the product quality can be realized by controlling the conversion depth or the naphtha yield in the product, for example, the heavy naphtha yield in the product is controlled to be 30-40 wt%.

In the operation process of industrial hydrocracking units, in order to ensure the activity of the catalyst in the cracking section, the nitrogen content is usually limited, especially the catalyst containing molecular sieves, and the limited refined oil nitrogen content is different according to the molecular sieve content. However, in actual production operation, it is difficult to ensure that the nitrogen content of the refined oil meets the limit requirement in many cases, and the following main points are: (1) Frequent planned or unplanned shutdowns lead to reduced catalyst activity; (2) the nitrogen content of the refined oil is higher due to the weight change of the raw materials; (3) The nitrogen content of the refined oil is higher due to the increase of the nitrogen content of the raw material; (4) The nitrogen content of refined oil is higher due to poisoning of the refined catalyst; (5) The planning changes to process high nitrogen marine oil or other high nitrogen raw materials (such as Liaohe oil).

The processing mode can lead to higher nitrogen content of refined oil, if the reaction temperature of the refining section is improved uniformly to aim at improving the denitrification rate, on one hand, the aim of the denitrification rate is difficult to achieve, on the other hand, the temperature of the outlet of the refining section is not matched with the temperature of the inlet of the cracking section, and hidden danger is caused to the safe production of the cracking section. Such a situation has appeared at present on industrial equipment, because short-term fluctuation of raw materials leads to insufficient denitrification depth of the refining section, the situation can only be compensated by increasing the reaction temperature, but too high outlet temperature leads to too high stream temperature entering the cracking section, and the lower bed layer can be controlled by using a large amount of cold hydrogen through step-by-step transmission of the bed layer, so that the production safety is not effectively ensured, and a temperature runaway accident can occur in serious cases.

The method not only meets the requirements of enterprises on heavy naphtha which is a current product, but also reduces the risk of temperature runaway of a catalyst bed of a cracking section, and once the refined oil nitrogen content fluctuates during actual production, the refined oil nitrogen content is not required to be controlled by one-taste temperature raising, meaningless efforts are made, and only proper and safe refined nitrogen content is required to be controlled according to a grading scheme, so that the influence of nitrogen on the catalyst can be offset as much as possible by gradually raising the temperature even if the upper catalyst is poisoned, and the lower catalyst is a catalyst with lower activity in grading, so that the temperature raising of the upper catalyst does not cause temperature runaway to the lower catalyst, safety control can be realized, and the upper catalyst has nitrogen poisoning signs, but only needs to be gradually raised to reduce the influence according to a conventional hydrocracking operation mode, and the mode of gradually controlling the temperature raising to promote activity recovery is one of the characteristics of the method. In the temperature raising process, the requirement of the device on product distribution can be met to the greatest extent, and the adaptability of the device can be improved on the premise of safe production as long as the temperature raising is properly controlled. For enterprises with large production fluctuation or frequent raw material change, the method can realize long-period stable operation. Enterprises with great requirements on product distribution are reasonably and practically provided with the catalyst grading technology.

Detailed Description

The operation and effects of the process according to the invention are further illustrated below by way of examples and comparative examples, which are not to be construed as limiting the process according to the invention, in the context of the invention,% being in mass% unless otherwise specified. The properties of the raw oil are shown in Table 1, and the operating conditions and cycle comparisons are shown in Table 2.

Example 1

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of the cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 355 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 367 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 35 mug/g, the independent temperature raising compensation is performed on the FC-52 in order to control the yield of heavy naphtha to be about 35%, the reaction temperature of the FC-52 is raised to 364 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst beds is simultaneously raised, the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 36 months.

Example 2

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 40%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of a cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 360 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 372 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 35 mug/g, the separate temperature raising compensation is carried out on the FC-52 in order to control the yield of heavy naphtha to be about 40%, the reaction temperature of the FC-52 is raised to 369 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst beds is raised, the yield of heavy naphtha is controlled to be about 40%, and the pre-conversion period of the blending processing is 31 months.

Example 3

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 30%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of a cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 350 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 362 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 35 mug/g, the separate temperature raising compensation is carried out on the FC-52 in order to control the yield of heavy naphtha to be about 30%, the reaction temperature of the FC-52 is raised to 359 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst bed is raised, and the yield of heavy naphtha is controlled to be about 30%, and the pre-conversion period of the blending processing is 41 months.

Example 4

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of the cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:2, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 353 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 365 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 35 mug/g, the separate temperature raising compensation is carried out on the FC-52 in order to control the yield of heavy naphtha to be about 35%, the reaction temperature of the FC-52 is raised to 362 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst bed is raised, and the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 38 months.

Example 5

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of the cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 355 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 367 ℃, the blending processing of raw material 2 is required in the production, the proportion is 40wt%, the nitrogen content of refined oil is increased to be 50 mug/g, the independent temperature raising compensation is performed on the FC-52 in order to control the yield of heavy naphtha to be about 35%, the reaction temperature of the FC-52 is raised to 364 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst beds is simultaneously raised, the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 30 months.

Example 6

In the processing of the raw material 1 in the table 1, the nitrogen content of refined oil is 10 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of a cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 354 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 366 ℃, the blending processing of the raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 35 mug/g, the independent temperature raising compensation is performed on the FC-52 in order to control the yield of the heavy naphtha to be about 35%, the reaction temperature of the FC-52 is increased to 363 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst beds is increased, the yield of the heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 37 months.

Example 7

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-32 hydrocracking catalysts are used in the grading of a cracking section, the filling volume ratio of the FC-52 and the FC-32 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 355 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 368 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 35 mug/g, the separate temperature raising compensation is carried out on the FC-52 in order to control the yield of heavy naphtha to be about 35%, the reaction temperature of the FC-52 is raised to 365 ℃, the reaction temperature of the FC-52 and the FC-32 hydrocracking catalyst bed is raised, and the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 35 months.

Example 8

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of the cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 355 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 367 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to be 45 mug/g, the independent temperature raising compensation is performed on the FC-52 in order to control the yield of heavy naphtha to be about 35%, the reaction temperature of the FC-52 is raised to 367 ℃, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst beds is raised, the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 37 months.

Comparative example 1

Raw material 1 in Table 1 is processed, refined oil nitrogen content is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, an FC-52 hydrocracking catalyst is used in a cracking section, the average reaction temperature of the FC-52 hydrocracking catalyst is 360 ℃ in the normal operation process, the proportion of raw material 2 is 30wt% because of the blending processing of raw material 2, the refined oil nitrogen content is increased to be 35 mug/g, the temperature raising compensation is carried out on FC-52 for controlling the yield of heavy naphtha to be about 35%, but abnormal temperature flying phenomenon occurs due to the fact that the activities of catalysts of all beds are not matched in the process of increasing the temperature of beds, the reaction temperature of a hydrocracking catalyst bed is continuously increased after recovery, the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of blending processing is 30 months.

Comparative example 2

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of a cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 355 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 367 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of refined oil is increased to 35 mug/g, the temperature of the refining section is controlled to be reduced to 15 mug/g by increasing the reaction temperature of the refining section, but the outlet temperature of the refining section is too high, so that the temperature of a cracking section catalyst bed is in a fly-temperature phenomenon, the cracking section is restarted after recovery, the reaction temperature of the FC-52 and the FC-76 hydrocracking catalyst bed is increased, the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 28 months.

Comparative example 3

In the processing of raw material 1 in Table 1, the nitrogen content of refined oil is 15 mug/g, the yield of heavy naphtha is controlled to be about 35%, FC-52 and FC-76 hydrocracking catalysts are used in the grading of the cracking section, the filling volume ratio of the FC-52 and the FC-76 hydrocracking catalysts is 1:3, the average reaction temperature of the FC-52 hydrocracking catalysts in the normal operation process is 355 ℃, the average reaction temperature of the FC-76 hydrocracking catalysts is 367 ℃, the blending processing of raw material 2 is required in the production, the proportion is 30wt%, the nitrogen content of the refined oil is increased to be 35 mug/g, the reaction temperature of the FC-52 and FC-76 hydrocracking catalyst beds is improved in order to control the yield of heavy naphtha to be about 35%, the yield of heavy naphtha is controlled to be about 35%, and the pre-conversion period of the blending processing is 32 months.

Table 1 table of raw oil properties

TABLE 2 hydrogenation reaction conditions (cracking)

As can be seen from the above examples and comparative examples, the hydrocracking apparatus not employing the present invention has problems of temperature runaway or mismatching of temperature increase. The hydrocracking device of the invention can furthest reduce the influence of higher nitrogen content of refined oil on the hydrocracking catalyst by the sectional deactivation adjustment of the catalyst, balance and coordinate the adsorption and desorption processes of nitrogen, protect the main catalyst at the bottom from the influence of initial nitrogen, and play a promoting role in the performance of the catalyst and long-period stability.

In the process flow, only the hydrocracking catalyst is replaced and the temperature control is assisted, so that the ideal comprehensive processing effect is obtained. The device has the advantages of saving equipment, low operation cost and the like in practical application, can utilize heat extraction and exchange optimization to reduce the energy consumption of the device to a certain extent, reduces investment and has wide application prospect.

Claims

1. A hydrocracking process characterized by: comprises a hydrogenation pretreatment reaction zone and a hydrogenation cracking reaction zone, wherein the hydrogenation cracking reaction zone is sequentially filled with a high-activity hydrogenation cracking catalyst and a low-activity hydrogenation cracking catalyst along the material direction, when the nitrogen content of effluent of the hydrogenation pretreatment reaction zone is higher than 20 mug/g, the average reaction temperature of the high-activity hydrogenation cracking catalyst is improved to control the quality of products, when the average reaction temperature of the high-activity hydrogenation cracking catalyst and the average reaction temperature of the low-activity hydrogenation cracking catalyst are different by 0-3.5 ℃, the average reaction temperature of the high-activity hydrogenation cracking catalyst and the average reaction temperature of the low-activity hydrogenation cracking catalyst are synchronously adjusted to control the quality of products, the hydrogenation cracking reaction condition is that the operation pressure is 10.0-16.0 MPa, the hydrogen oil volume ratio is 600:1-1200:1, and the volume space velocity is 0.1-5.0 h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the When the nitrogen content of effluent of the hydrogenation pretreatment reaction zone<20 mug/g, wherein the average reaction temperature of the high-activity hydrocracking catalyst in the hydrocracking reaction zone is 350-360 ℃, and the average reaction temperature of the low-activity hydrocracking catalyst is 362-372 ℃;

the filling volume ratio of the high-activity hydrocracking catalyst to the low-activity hydrocracking catalyst is 1:1.5-1:3.5, the molecular sieve mass content of the high-activity hydrocracking catalyst is 1.2-2.2 times that of the low-activity hydrocracking catalyst, the high-activity hydrocracking catalyst contains 10% -30% of active metal oxide and more than 50% of molecular sieve by weight, the active metal comprises one or more of Wo, mo, co, ni, the molecular sieve comprises Y-type or USY molecular sieve, the low-activity hydrocracking catalyst contains 15% -40% of active metal oxide and 20% -40% of molecular sieve by weight, the active metal comprises one or more of Wo, mo, co, ni, and the molecular sieve comprises Y-type or USY molecular sieve.

2. The method according to claim 1, characterized in that: when the nitrogen content of the effluent of the hydrogenation pretreatment reaction zone is 30-50 mug/g, the average reaction temperature of the high-activity hydrocracking catalyst is improved, and the product quality is controlled.

3. The method according to claim 1, characterized in that: when the average reaction temperature of the high-activity hydrocracking catalyst and the average reaction temperature of the low-activity hydrocracking catalyst are different by 0-2.5 ℃, the average reaction temperature of the high-activity hydrocracking catalyst and the average reaction temperature of the low-activity hydrocracking catalyst are synchronously adjusted to control the quality of the product.

4. The method according to claim 1, characterized in that: the hydrogenation pretreatment reaction zone is filled with a hydrogenation refining catalyst, and the hydrogenation refining catalyst comprises a carrier and a supported hydrogenation metal.

5. The method according to claim 4, wherein: based on the weight of the hydrofining catalyst, the catalyst comprises 10% -35% of hydrogenated metal oxide of VIB group in periodic table; 1% -7% of VIII family hydrogenation metal oxide.

6. The method according to claim 4, wherein: 15% -30% of a hydrogenated metal oxide of a VIB group in the periodic table of elements by taking the weight of the hydrofining catalyst as a reference; 1.5% -6% of VIII family hydrogenation metal oxide.

7. The method according to claim 1, characterized in that: the operating conditions of the hydrotreatment reaction zone are as follows: the operating pressure is 10.0-16.0 MPa, the hydrogen-oil volume ratio is 500:1-1000:1, and the volume airspeed is 0.2-6.0 h ^-1 。

8. The method according to claim 7, wherein: the operating conditions of the hydrotreatment reaction zone are as follows: the operating pressure is 12.0-15.0 MPa, and the hydrogen-oil volume ratio is 600:1-1000:1.

9. The method according to claim 1, characterized in that: the hydrocracking reaction zone is filled with high-activity hydrocracking catalyst and low-activity hydrocracking catalyst in sequence along the material direction, the filling volume ratio of the high-activity hydrocracking catalyst to the low-activity hydrocracking catalyst is 1:2-1:3, and the molecular sieve mass content of the high-activity hydrocracking catalyst is 1.5-2 times of that of the low-activity hydrocracking catalyst.

10. The method according to claim 1, characterized in that: the high-activity hydrocracking catalyst contains 15-25% of active metal oxide by weight.

11. The method according to claim 1, characterized in that: the low-activity hydrocracking catalyst contains 18% -35% of active metal oxide by weight.

12. The method according to claim 1, characterized in that: when the nitrogen content of effluent of the hydrogenation pretreatment reaction zone is less than 15% mug/g, the average reaction temperature of the high-activity hydrocracking catalyst in the hydrocracking reaction zone is 350-355 ℃; the average reaction temperature of the low-activity hydrocracking catalyst is 365-370 ℃.

13. The method according to claim 1, characterized in that: the hydrocracking reaction condition is that the operating pressure is 12.0-15.0 MPa, and the volume ratio of hydrogen to oil is 700:1-1000:1.

14. The method according to claim 1, characterized in that: the control of product quality is achieved by controlling the depth of conversion or the yield of naphtha in the product.

15. The method according to claim 14, wherein: the yield of heavy naphtha in the product is controlled to be 30-40 wt%.