CN108018074B

CN108018074B - Heavy oil hydrotreating method for improving catalyst utilization rate

Info

Publication number: CN108018074B
Application number: CN201610968483.3A
Authority: CN
Inventors: 吴锐; 刘涛; 韩照明; 王军; 袁俊; 曹晓羿; 朱文权; 杨大为; 徐加龙
Original assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Current assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Priority date: 2016-11-01
Filing date: 2016-11-01
Publication date: 2020-10-16
Anticipated expiration: 2036-11-01
Also published as: CN108018074A

Abstract

The invention discloses a heavy oil hydrotreating method for improving the utilization rate of a catalyst. After the heavy oil raw oil is mixed with hydrogen, firstly, the mixture passes through a hydrogenation pretreatment area to carry out hydrogenation demetalization and partial desulfurization reaction; the reaction effluent enters a hydrotreating reaction zone to carry out hydrodesulfurization and hydrodenitrogenation reactions; wherein the reaction temperature of the hydrotreating reaction zone is higher than the reaction temperature of the hydrotreating reaction zone. In the method, the hydrogenation pretreatment reaction zone reacts at a higher temperature, most metal impurities in the material can be removed, the inactivation reason of the desulfurization and/or denitrification catalyst in the hydrogenation treatment reaction zone is changed from the past metal deposition and carbon deposit inactivation into only carbon deposit inactivation, and then the desulfurization catalyst and the denitrification catalyst can be regenerated after being used for one period, so that the running period of the hydrogenation device is prolonged, the running efficiency of the device is increased, and the economy is improved.

Description

Heavy oil hydrotreating method for improving catalyst utilization rate

Technical Field

The invention relates to the field of petroleum refining, in particular to a heavy oil hydrotreating method for improving the utilization rate of a catalyst.

Background

At present, the demand of oil markets at home and abroad on light and medium oils is still in a continuously rising trend, and the demand on heavy oils such as fuel oil is in a descending trend. In addition, due to the increasing pressure of environmental protection, the quality standard requirements of petroleum products, especially vehicle gasoline and diesel oil products, are generally improved in various countries. Under the market trend, the oil refining technology which can realize the lightening of heavy oil at a more economic and reasonable cost and can enable the obtained product to meet the continuously rigorous specification of gasoline and diesel products becomes one of the key technologies developed by oil refining technology developers at home and abroad.

Among various technological processes for the conversion of heavy oil into light oil, the process of first hydrotreating the heavy oil and then catalytically cracking the hydrogenated tail oil is a good technological process. Through hydrogenation, the contents of metal, sulfur, nitrogen and asphaltene in the raw materials are obviously reduced, the hydrogen-carbon ratio is improved, and further excellent raw materials are provided for devices such as catalytic cracking devices, delayed coking devices and the like. At present, the main hydrogenation processes mainly comprise a boiling bed process, a suspension bed process, a moving bed process and a fixed bed process, wherein the suspension bed process and the moving bed process are still immature and have higher cost. The boiling bed investment is high and the operation difficulty is large. The fixed bed is developed quickly due to low cost, simple operation, small safety and mature technology.

In the prior art, the hydrogenation treatment of heavy oil products is realized by a plurality of hydrogenation reactors provided with a plurality of hydrogenation catalyst beds. However, the heavy oil product generally has a high viscosity and high metal impurities or asphaltenes, and during the hydrogenation process, metals and coke are gradually deposited on the catalyst, so that the catalyst is easily and rapidly deactivated, the bed layer is blocked, and the pressure is increased, which is particularly serious in the first hydrogenation reactor.

CN1349554A discloses a method for hydrotreating heavy feedstock in an upflow reactor system with a layered catalyst bed. Heavy feedstocks contaminated with metals, sulfur and carbon residue are hydrotreated with an upflow fixed bed reactor with at least two catalysts of different hydrogenation activity. But the method has short operation period, generally not exceeding 1 year.

CN1484684A proposes a method for hydrotreating heavy hydrocarbon fractions by replacing the reactor and by short-circuiting the reactor, in which the guard reactor is a traditional downflow fixed bed reactor, if the content of Ca and Fe in the raw material is high, the pressure drop of the reactor will increase even if the capability of depositing metal in the channels of the guard agent is not saturated, because the reactant flow is from top to bottom, if these solid impurities block the gaps between the catalysts, and thus it is necessary to switch to another reactor.

CN102453530A discloses a hydrogenation method for processing heavy oil, in which raw oil of heavy oil and hydrogen are mixed and then enter a hydrogenation protection reaction zone, and then directly enter a hydrotreating reaction zone, and at least two parallel-connected upflow hydrogenation protection reactors which can be alternately switched for use are arranged in the hydrogenation protection zone. The invention adopts the method of grading four hydrogenation protective agents, which is beneficial to removing metals, thereby preventing blockage, prolonging the service life of the main catalyst and prolonging the operation period of the device. The method still has little improvement on the device operation period.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a heavy oil hydrotreating method for improving the utilization rate of a catalyst, in particular to a heavy oil hydrotreating method which can give full play to the performances of catalysts in different reaction zones and increase the running period of a device.

The heavy oil hydrotreating method for improving the utilization rate of the catalyst provided by the invention comprises the following steps:

(1) providing at least one hydrotreating reaction zone and at least one hydrotreating reaction zone; the hydrogenation pretreatment reaction zone comprises a hydrogenation protection catalyst and a hydrogenation demetalization catalyst, and the hydrogenation treatment reaction zone comprises a hydrodesulfurization catalyst and a hydrodenitrogenation (carbon residue conversion) catalyst;

(2) mixing heavy oil raw oil with hydrogen, feeding the mixture into a hydrogenation pretreatment reaction zone, carrying out hydrogenation reaction under the condition of hydrogenation pretreatment, removing 40-90 wt% of metal impurities, and removing 20-70 wt% of sulfur to obtain a reaction effluent with reduced metal content;

(3) the reaction effluent obtained in the step (2) enters a high-pressure separator, and gas and liquid phases are separated; the gas obtained by separation is subjected to desulfurization and compression by a compressor and then is circulated to a hydrogenation pretreatment reaction zone;

(4) mixing the liquid product obtained by separation in the step (3) with part of material flow recycled in the hydrotreating area, feeding the mixture into a hydrogen mixing tank for hydrogen mixing, feeding the mixed oil after saturated hydrogen dissolution into a liquid phase hydrotreating reactor, and carrying out contact reaction with a hydrodesulfurization catalyst and a hydrodenitrogenation catalyst under the hydrotreating condition to obtain reaction effluents with reduced sulfur content and nitrogen content;

(5) and (4) circulating one part of the liquid phase hydrogenation reaction effluent obtained in the step (4) to a hydrogen mixing tank, and decompressing the other part of the liquid phase hydrogenation reaction effluent to flow out of the device.

The hydrotreating method provided by the invention has the advantage that the average reaction temperature of the hydrogenation pretreatment reaction zone in the step (2) is 5-40 ℃ higher than the average reaction temperature of the hydrotreating reaction zone in the step (4), and preferably 10-30 ℃.

The hydrotreating method according to the present invention, wherein two or more hydrotreating pretreatment reaction zones, which are usually reaction zones disposed in parallel and switchable in operation, are provided in step (1). Therefore, the method of the present invention may further comprise the step (6) of cutting one of the hydrogenation pretreatment reaction zones out of the reaction flow and cutting the second hydrogenation pretreatment reaction zone into the process flow when the operation requirements cannot be met, wherein the cut hydrogenation pretreatment reaction zone can be used for replacing the catalyst, i.e., discharging the deactivated old catalyst and recharging the catalyst with fresh and/or regenerated catalyst.

The condition that the hydrogenation pretreatment reaction zone cannot meet the operation requirement means that: the effluent of the hydrogenation pretreatment reaction zone cannot meet the feeding requirement of a downstream hydrogenation treatment zone, or the pressure drop of at least one catalyst bed layer in the hydrogenation pretreatment reaction zone reaches the upper pressure drop limit or hot spots appear in the catalyst bed layer.

The criteria that fail to meet the feed requirements of the downstream hydroprocessing reaction zone may be: the metal content in the liquid product at the outlet of the hydrogenation pretreatment reaction zone exceeds a specified value. Specifically, the standard for judging whether the liquid product at the outlet of the hydrogenation pretreatment reaction area meets the feeding requirement of the downstream hydrogenation treatment area is that the metal content (the sum of the contents of Ni, V, Fe, Na, Ca and the like) in the effluent liquid exceeds any one value in the range from 8 [ mu ] g/g to 50 [ mu ] g/g, preferably exceeds any one value in the range from 10 [ mu ] g/g to 30 [ mu ] g/g.

The upper limit of the pressure drop is 0.4-0.8 times, preferably 0.5-0.8 times of the maximum pressure drop of the reactor design. The hot spot is that the radial temperature difference in at least one catalyst bed reaches 15-50 ℃, preferably 15-30 ℃.

In the heavy oil hydrotreating method of the present invention, the heavy oil raw oil refers to hydrocarbons with high asphaltene content obtained from topped crude oil, petroleum residual oil, oil sand, bitumen, shale oil, liquefied coal or reclaimed oil. The heavy oil raw oil generally contains various pollutants, the carbon residue value of the heavy oil raw oil is high, the content of impurities such as sulfur, nitrogen and the like is high, and the metal content of the heavy oil raw. The method is particularly suitable for treating heavy oil raw materials with high metal content, particularly heavy oil raw materials with metal (nickel and vanadium) content more than 60 mug/g and/or iron content more than 10 mug/g and/or calcium content more than 10 mug/g.

In the method of the present invention, the hydrogenation protection catalyst used in the hydrogenation pretreatment reaction zone may be a residual oil hydrogenation protective agent, or may be prepared according to the nature of the raw material by a conventional method in the art. The residual oil hydrogenation protective agent is a conventional catalyst in the field, and a commercial product can be adopted. The hydrogenation protective agent is a catalyst which takes a porous refractory inorganic oxide such as alumina as a carrier and takes one or more oxides of metals in VIB group and/or VIII group such as W, Mo, Co and Ni as active components, for example, the FZC series residual oil hydrogenation protective agent produced by catalyst division of China petrochemical industry, Inc.

The hydrodemetallization catalyst can be a residual hydrodemetallization catalyst or can be prepared according to the properties of the raw materials by the conventional method in the field. These catalysts are generally based on porous refractory inorganic oxides, such as alumina, as a support, one or more oxides of metals of the VIB and/or VIII families, such as W, Mo, Co, Ni, etc., as active components, optionally with the addition of other various assistants, such as P, Si, F, B, etcThe catalyst of (1). The hydrodemetallization catalyst takes the total weight of the catalyst as a reference, and is calculated by oxides, the content of molybdenum and/or tungsten is 0.5-15 wt%, the content of cobalt and/or nickel is 0.3-8 wt%, and the balance is an alumina carrier. The alumina carrier is bimodal porous alumina, the pore volume of the alumina carrier is 0.5-2.0 ml/g, and the specific surface area of the alumina carrier is 120-350 m²The pore volume of the porous material with the pore diameter of 10-30 nanometers accounts for 30-90 percent of the total pore volume, the pore volume of the porous material with the pore diameter of 100-2000 nanometers accounts for 10-50 percent of the total pore volume, and the sum of the pore volumes of the porous materials with the pore diameters of less than 10 nanometers, between 30-100 nanometers and more than 2000 nanometers accounts for less than 20 percent of the total pore volume. In order to take account of the diffusion process of the reactant molecules and the active surface required for the reaction, the catalyst with bimodal pore distribution of large and medium pores shows better performance in the reaction process of the hydrogenation pretreatment reaction zone. In the hydrogenation pretreatment reaction zone, the filling volume ratio of the hydrogenation protection catalyst to the hydrogenation demetallization catalyst is generally 5: 95-95: 5, and preferably 10: 90-60: 40.

The heavy oil hydrotreating process according to the present invention may further include a hydrodesulfurization catalyst in the hydrotreating pretreatment reaction zone, preferably downstream of the hydrodemetallization catalyst. The loading amount of the hydrodesulfurization catalyst is 0-30 v%, preferably 5-30 v% of the loading amount of the hydrodemetallization catalyst.

The hydrodesulfurization catalyst may be a residue hydrodesulfurization catalyst as is conventional in the art or may be prepared according to the nature of the feedstock by methods conventional in the art. The catalyst is prepared with porous refractory inorganic oxide as carrier, VIB and/or VIII metals as active component, and optional assistants, such as P, Si, F, B and other elements. Because the metal content in the product of the hydrogenation pretreatment reaction zone in the technology is strictly limited, the improved hydrodesulfurization catalyst is preferably used in order to better exert the overall performance of the catalyst system, the overall performance of the catalyst is between that of the conventional hydrodemetallization catalyst and that of the hydrodesulfurization catalyst, namely, the pore diameter of the catalyst is slightly larger than that of the conventional hydrodesulfurization catalyst, the catalyst has better metal-containing capacity, the activity of the catalyst is slightly higher than that of the conventional hydrodemetallization catalyst, and the catalyst has stronger hydrodesulfurization capacity.

The hydrodesulfurization catalyst takes the total weight of the catalyst as a reference, and is calculated by oxides, the content of molybdenum and/or tungsten is 10-25 wt%, the content of cobalt and/or nickel is 1-6 wt%, and the balance is an alumina carrier. The pore volume of the alumina is not less than 0.35 ml/g, and the specific surface area is 150-350 m²And the pore volume of the pores with the pore diameters of 6-15 nanometers accounts for more than 70 percent of the total pore volume.

In the process of the present invention, the reaction conditions may be determined according to the nature of the starting materials and the desired reaction results, as is common knowledge in the art. Generally, the reaction conditions in the hydrogenation pretreatment reaction zone are that the reaction pressure is 5MPa to 35MPa, preferably 10MPa to 20MPa, the average reaction temperature is 340 ℃ to 430 ℃, preferably 340 ℃ to 420 ℃, and the liquid hourly space velocity is 0.1h^-1～5.0h^-1Preferably 0.3h^-1～3.0h^-1The volume ratio of hydrogen to oil is 200 to 2000, preferably 300 to 1500.

In the method, the catalyst used in the hydrotreating reaction zone can be a common heavy oil hydrotreating catalyst in the field, and the optimal catalyst property can be optimized according to the material property. The catalyst generally includes various catalysts such as hydrodesulfurization catalyst and hydrodenitrogenation catalyst. These catalysts are generally catalysts in which a porous refractory inorganic oxide such as alumina is used as a carrier, oxides of metals of the VIB group and/or VIII group such as W, Mo, Co, Ni and the like are used as active components, and other various auxiliary agents such as P, Si, F, B and the like are selectively added.

In the hydrotreating reaction zone, the filling volume ratio of the hydrodesulfurization catalyst to the hydrodenitrogenation catalyst is generally 20: 80-80: 20, and preferably 40: 60-70: 30.

The hydrodenitrogenation catalyst has the following properties: based on the total weight of the catalyst, the content of molybdenum and/or tungsten is 12-30 wt% calculated by oxide, the content of cobalt and/or nickel is 3-12 wt%, and the balance is alumina carrier. The pore volume of the alumina is not less than 0.35 ml/g, and the specific surface area is 150-350 m²Per gram, the pore volume of the pores with the pore diameter of 6-15 nanometers accounts for the total40-75% of the pore volume.

According to the method, a small amount of hydrodemetallization catalyst can be further included in the hydrotreating reaction zone, the hydrodemetallization catalyst is filled at the upstream of the hydrodesulfurization catalyst, and the filling amount of the hydrodemetallization catalyst is 0-30 v%, preferably 2-30 v%, of the total filling amount of the catalyst in the hydrotreating reaction zone.

The order of loading the catalyst in the hydrotreating reaction zone is generally such that the reactant stream is contacted with the hydrodemetallization catalyst, the hydrodesulfurization catalyst and the hydrodenitrogenation catalyst in this order, although there is a technique of loading these catalysts in a mixed manner. The above-described catalyst loading techniques are well known to those skilled in the art. The catalyst can be a commercially available commodity, such as a hydrogenation demetalization catalyst, a desulfurization catalyst and a denitrification catalyst of FZC series residual oil, which are developed and produced by China petrochemical industry research institute, and can also be prepared according to the existing method in the field.

In the method, the reaction conditions of the hydrotreating reaction zone are that the reaction pressure is 5MPa to 35MPa, preferably 10MPa to 20MPa, the average reaction temperature is 320 ℃ to 420 ℃, preferably 330 ℃ to 410 ℃, and the liquid hourly space velocity is generally 0.1h^-1～5.0h^-1Preferably 0.3h^-1～3.0h^-1The liquid phase circulation ratio (mass ratio of circulating oil to fresh raw oil) is 0.1:1 to 10:1, preferably 0.2:1 to 3: 1.

In the method, the two reaction zones of the hydrogenation pretreatment and the hydrotreating belong to series operation, so the pressure of the two reaction zones is the same pressure grade, and slight difference can occur due to the pressure drop.

In the method, the hydrogenation pretreatment reaction zone mainly carries out the hydrodemetallization and partial hydrodesulfurization reaction, and the hydrogenation pretreatment reaction zone is operated at a higher temperature, so that the demetallization reaction is favorably carried out, and the activity of the hydrogenation demetallization catalyst can be fully utilized. The material without a large amount of metal impurities enters a hydrotreating reaction zone for further reaction. Because a large amount of metal impurities are removed, the poison of the material entering the hydrotreating reaction zone to the catalyst in the hydrotreating zone is greatly reduced, the utilization rate of the hydrodesulfurization catalyst and the hydrodenitrogenation catalyst can be obviously improved, the service life of the catalyst in the hydrotreating zone is prolonged, and the running period of the whole hydrotreating device is further effectively prolonged. In order to reasonably match the operation of the two reaction zones, the average reaction temperature of the hydrogenation pretreatment reaction zone is 5-40 ℃ higher than that of the hydrogenation treatment reaction zone, and preferably 10-30 ℃ higher than that of the hydrogenation treatment reaction zone.

In the method, one or more hydrogenation protection reactors can be arranged in the hydrogenation pretreatment reaction zone, each hydrogenation protection reactor is at least provided with one hydrogenation protection catalyst bed layer, and if a plurality of catalyst bed layers are arranged, quenching hydrogen can be injected between the reaction bed layers to control the reaction temperature.

In the method of the present invention, one or more reactors may be provided in the hydrotreating reaction zone, and usually 2 to 5 reactors, preferably 2 to 3 reactors are provided. The number of the catalyst bed layers in each reactor is generally 1-5, preferably 1-3, and if more than two catalyst bed layers are arranged, saturated hydrogen-dissolved generated oil can be injected between the catalyst bed layers, so that the amount of dissolved hydrogen in liquid in the reactor can be further increased, and the purposes of hydrodesulfurization and hydrodenitrogenation can be better realized. In the hydrotreating reaction zone, a hydrodemetallization catalyst (optional), a hydrodesulfurization catalyst and a hydrodenitrogenation catalyst are sequentially filled along the flow direction of the reactant stream. In the process of the present invention, the loading of the catalyst in each catalyst bed can be selected specifically according to the requirements of the nature of the raw material, the nature of the catalyst selected and the nature of the product.

In order to achieve better effect, more than two switchable hydrogenation pretreatment reaction zones can be adopted. The switchable meaning means that a plurality of hydrogenation pretreatment reaction zones are arranged, and each hydrogenation pretreatment reaction zone can be independently connected with a subsequent hydrogenation treatment reaction zone or independently cut out from the hydrogenation treatment reaction zone.

According to the hydrotreating process of the present invention, the purpose of providing a plurality of switchable hydrotreating reaction zones is to enable continuous hydrogenation protection of the catalyst in each reactor of the hydrotreating reaction zone by switching. Therefore, the number of reactors and the connection relationship of the reactors provided for each hydrogenation pretreatment reaction zone are only required to satisfy the purpose of switching use. Preferably, the number of the hydrogenation pretreatment reaction zones is 2, 1 reactor is arranged in each hydrogenation pretreatment reaction zone, the two hydrogenation pretreatment reaction zones are preferably connected in parallel, and only one of the two hydrogenation pretreatment reaction zones is in an online processing state. The hydrogenation pretreatment reaction zone is sequentially filled with hydrogenation protective agent, hydrogenation demetalization catalyst and hydrogenation desulfurization catalyst, and the grading mode of various protective agents and catalysts can be determined according to the properties of raw materials and conventional knowledge in the field.

In the method, the specific meaning that only one of the two hydrogenation pretreatment reaction zones is in an on-line state is that when the first hydrogenation pretreatment reaction zone cannot meet the feeding requirement of a downstream hydrogenation treatment zone or the pressure drop of at least one catalyst bed layer in the first hydrogenation pretreatment reaction zone reaches the upper pressure drop limit or a hot spot appears in the catalyst bed layer, all reactors in the first hydrogenation pretreatment reaction zone are cut out, and the reactor in the second hydrogenation pretreatment reaction zone is cut in at the same time. When the second hydrogenation pretreatment reaction zone cannot meet the feeding requirement of a downstream hydrogenation treatment reaction zone, or the pressure drop of at least one catalyst bed layer in the second hydrogenation pretreatment reaction zone reaches the upper limit of the pressure drop, or hot spots appear in the catalyst bed layers and cannot be continuously operated, all the protective agents and the catalysts in all the reactors can be replaced after the device is shut down. And the reactor in the second hydrogenation pretreatment reaction zone can be cut out according to the activity of the catalyst in the hydrotreating reaction zone, and the reactor in the first hydrogenation pretreatment reaction zone with the protective agent and the catalyst replaced is cut in, and the circulation is carried out until the catalyst in the hydrotreating reaction zone can not meet the operation requirement.

The flow direction of the feedstock in the hydrogenation protection zone and the hydrotreating zone is not particularly limited in the present invention, and each of the reactors in the hydrotreating reaction zone and the hydrotreating reaction zone may be an upflow reactor or a downflow reactor.

In the prior art, although the heavy oil hydrotreater has the influence of cold hydrogen according to the material flowing direction, the reaction temperature generally tends to be low before and high after, namely, the average reaction temperature of several catalyst beds such as a hydrogenation protection catalyst, a hydrogenation demetalization catalyst, a hydrogenation desulfurization catalyst and/or a hydrogenation denitrification catalyst is increased in sequence in the whole period from the initial stage to the final stage of operation. Meanwhile, the existing catalyst grading system is set to achieve the purposes of synchronously inactivating all reactors and synchronously replacing the catalyst at the final stage of operation. Therefore, during operation, when the pressure drop of the first reactor rises or hot spots occur, or when the hydrogenated product cannot meet the requirements of downstream equipment, the whole equipment needs to be stopped immediately to replace all the catalyst. In this case, the catalyst in the downstream hydrodesulfurization and/or denitrogenation reactor is also already substantially "deactivated". The operating cycle of the plant is therefore limited by the service life of the catalyst in the first reactor. Even for hydroprocessing processes employing reactor switching operation for hydroprocessing protection (such as CN1484684A and CN 102453530A), the operation cycle of the whole set of equipment is limited by the service life of the catalyst in the first reactor.

After conducting a great deal of research on the existing hydrotreating process, the inventors of the present application unexpectedly found that: in the prior art, after the hydrotreater is shut down due to the hot spot and/or pressure drop of the hydrogenation protection catalyst bed, the desulfurization catalyst and denitrification catalyst used in the rear part (downstream) of the hydrotreater are deactivated, but the deactivation is caused by the blockage of the pore openings of the catalyst channels by the deposited metal, and the deposited metal in the interior of the catalyst channels is not much. Specifically analyzing the reason, the applicant believes that: in the middle and later periods of the operation of the device, the metal in the raw oil completely penetrates through the hydrogenation protection catalyst and the demetallization catalyst bed layer and directly enters the rear desulfurization catalyst and denitrification catalyst bed layers. Because the pore diameter of the desulfurization catalyst and/or the denitrification catalyst is small, the removed metal cannot enter the inside of the pore channel and is deposited near the pore opening of the catalyst, thereby causing the deactivation of the desulfurization catalyst and the denitrification catalyst. In this case, the deactivation of the hydrodesulfurization catalyst and/or the hydrodenitrogenation catalyst is not completely caused by the excessive carbon deposition of the catalyst itself, but is more caused by the fact that the desulfurization and/or denitrification catalyst, which should have a larger hydrodesulfurization and/or denitrification function, has a hydrodemetallization function after the feedstock oil penetrates the hydrogenation protection catalyst bed and the hydrodemetallization catalyst bed. Meanwhile, after the catalyst originally designed for desulfurization, denitrification and/or carbon residue removal bears part of the hydrodemetallization function, the demetallization function cannot be well realized due to the limitation of the pore structure of the catalyst, and the reduction of the desulfurization, denitrification and/or carbon residue removal capability is caused, so that the waste of the catalyst function is caused, and the activity of the hydrodesulfurization and/or hydrodenitrogenation catalyst cannot be fully utilized.

The inventors of the present invention have found through extensive studies that it is possible to divide the entire apparatus into a hydrotreating reaction zone and a hydrotreating reaction zone, wherein the hydrotreating reaction zone is operated at a relatively high reaction temperature and the hydrotreating reaction zone is operated at a relatively low reaction temperature. According to the technical scheme, the metal content of the material at the outlet of the hydrogenation pretreatment reaction zone is controlled firstly, namely most metal impurities in the raw oil are removed in the hydrogenation pretreatment reaction zone, only a small amount of metal impurities which are difficult to remove are remained, and meanwhile, partial hydrodesulfurization is realized. And the hydrotreating reaction zone into which the reactant stream of the hydrotreating pretreatment reaction zone enters is operated at a relatively low temperature, i.e., hydrodesulfurization and hydrosaturation reactions are carried out at a relatively low temperature, so that the metal impurities can directly pass through the desulfurization catalyst and/or the denitrification catalyst without participating in the reactions, thereby avoiding permanent deactivation of the catalyst due to metal deposition. The product meets the feeding requirement of a downstream device through scheme optimization. Compared with the prior art, the method changes the prior catalyst system and the operation mode, namely, the prior art shows the trend of low front and high back according to the reaction temperature in the material flow direction and changes the prior art into the trend of high front and low back according to the reaction temperature in the material flow direction. The inventors of the present application have completed the present invention on this basis.

Compared with the prior art, the method has the following advantages:

1. the heavy oil hydrotreatment device is divided into the hydrogenation pretreatment reaction area and the hydrotreating reaction area, most metal impurities in materials are removed in the hydrogenation pretreatment reaction area, so that the toxicity of the materials entering the hydrotreating area to the catalyst in the hydrotreating area is greatly reduced, the activity of all the catalysts in the hydrotreating area can be fully utilized, and compared with the prior art, the running period of the device can be prolonged by 30-100%, so that the running efficiency of the device is increased, and the economy is improved.

2. The switchable protective reactor is adopted in the hydrogenation pretreatment reaction zone, so that the demetallization capability of the device is greatly improved, and the raw material with higher metal content can be processed.

3. Most of metal impurities in the materials are removed in the hydrogenation pretreatment reaction zone, so that the inactivation reason of the desulfurization catalyst and/or the denitrification catalyst in the hydrogenation treatment reaction zone is changed from the conventional metal deposition and carbon deposit inactivation into only carbon deposit inactivation, and the desulfurization catalyst and the denitrification catalyst can be regenerated after being used for one period, thereby greatly saving the purchase cost of the catalyst.

4. The hydrotreating zone adopts liquid phase hydrogenation, which has the advantages of reducing the temperature rise of the catalyst bed, effectively avoiding the generation of hot spots, simultaneously canceling the injection of quench hydrogen between beds and/or between reactors, and saturating part of aromatic hydrocarbon by hydrogenated circulating oil, thereby having the function of increasing hydrogen supply, inhibiting the formation of coke, and avoiding the deactivation of the catalyst due to carbon deposition, and further prolonging the service life of the catalyst.

5. The activity of the catalyst in the hydrotreating reaction zone is fully utilized, the treatment capacity of the device is improved, or the equipment investment is reduced.

Drawings

FIG. 1 is a schematic process flow diagram of a heavy oil hydrotreating method for improving catalyst utilization according to the present invention.

Fig. 2 is a schematic process flow diagram of comparative examples 2 and 3.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The attached drawing is a schematic flow chart of the principle of the heavy oil hydrotreating method for improving the catalyst utilization rate provided by the invention, and some auxiliary equipment (heat exchangers, pumps and the like) in the drawing are not marked but are well known to those skilled in the art.

The heavy oil hydrotreating method for improving the catalyst utilization rate provided by the invention has the following process:

firstly, after mixing fresh raw material residual oil from a pipeline 27, circulating hydrogen from a pipeline 26 and new hydrogen from a pipeline 25, entering a reactor 1 of a first hydrogenation pretreatment reaction zone through a pipeline 10, carrying out hydrodesulfurization and hydrodemetalization reaction in the presence of a catalyst, enabling a hydrogenation product to enter a high-pressure separator 5 from the top of the reactor 1 of the first hydrogenation pretreatment reaction zone through a pipeline 9 and a pipeline 13 for gas-liquid separation, enabling a hydrogen-rich gas 14 obtained by separation to be subjected to desulfurization and compression by a compressor 8 and then circulated to the hydrogenation pretreatment reaction zone, enabling a liquid product 15 obtained by separation to be mixed with circulating oil 23 of a liquid phase hydrogenation reaction effluent from a hydrogenation treatment zone of a pipeline 23, entering a hydrogen mixing tank 6, mixing and dissolving hydrogen with hydrogen introduced through a pipeline 17, discharging excess hydrogen through a pipeline 16, enabling the mixed oil after saturated and dissolved hydrogen to enter a liquid phase hydrogenation reactor 3 through a pipeline 18 for hydrogenation reaction, the reaction effluent enters a hydrogen mixing tank 7 through a pipeline 19, is mixed with hydrogen introduced through a pipeline 21 to dissolve hydrogen, the surplus hydrogen is discharged through a pipeline 20, the mixed oil after saturated hydrogen dissolution enters a liquid phase hydrogenation reactor 4 through a pipeline 22 to carry out hydrogenation reaction, one part of the obtained reaction effluent is circulated to the hydrogen mixing tank 6 through a pipeline 23, and the other part of the obtained reaction effluent flows out of the device through a pipeline 24.

When the reactor 1 in the first hydrogenation pretreatment reaction zone cannot meet the feeding requirement of a downstream hydrogenation treatment zone or the pressure drop of at least one catalyst bed layer in the reactor 1 reaches the upper pressure drop limit or a hot spot appears in the catalyst bed layer, the reactor is cut out and cut into the reactor 2 in the second hydrogenation pretreatment reaction zone (at this moment, the material enters the reactor 2 through the pipeline 12 and flows out of the reactor 2 through the pipeline 11) to continue to complete the hydrogenation treatment process, meanwhile, the catalyst in the reactor 1 in the first hydrogenation pretreatment reaction zone is replaced, and a fresh catalyst is filled again for standby. When the reactor 2 of the second hydrogenation pretreatment reaction zone cannot meet the feeding requirement of the downstream hydrogenation treatment reaction zone, or the pressure drop of at least one catalyst bed layer in the reactor 2 reaches the upper pressure drop limit or a hot spot incapable of being continuously operated appears in the catalyst bed layer, the reactor is cut out, and simultaneously the reactor 1 of the first hydrogenation pretreatment reaction zone is cut in to continuously complete the hydrogenation treatment process, and simultaneously the catalyst in the reactor 2 of the second hydrogenation pretreatment reaction zone is replaced, and a fresh catalyst is newly filled for standby. And circulating the above steps until the service life of the catalyst in the hydrotreating zone is reached.

The process of the present invention is further defined below with reference to specific examples. The properties of the feed oils used in examples and comparative examples are shown in Table 1, and the properties of the catalysts used are shown in Table 2. In table 2, a is a hydrogenation protection catalyst, B is a hydrodemetallization catalyst, C is a hydrodesulfurization catalyst, and D is a hydrodenitrogenation (carbon residue conversion) catalyst.

TABLE 1 Properties of the stock oils

TABLE 2 catalyst Properties

Example 1

According to the process flow illustrated in fig. 1, the hydrogenation pretreatment reaction area includes a first hydrogenation pretreatment reaction area and a second hydrogenation pretreatment reaction area that are switchable in operation, the first hydrogenation pretreatment reaction area is provided with a reactor 1, the second hydrogenation pretreatment reaction area is provided with a reactor 2, and the hydrogenation treatment reaction area includes a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4 that are arranged in series. According to the material flow direction, a hydrogenation pretreatment reaction zone (only one hydrogenation pretreatment reaction zone is on line in the operation process) is filled with a catalyst A, a catalyst B and a catalyst C, and the filling volume ratio of the catalysts is 2: 7: 1. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 1: 9, and the reactor 4 is filled with only a catalyst D.

In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is higher than that of the hydrogenation treatment zone, and the specific reaction conditions are shown in Table 3. The raw oil A sequentially flows through a reactor 1, a high-pressure separator 5, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, and the content of metal (Ni + V) in effluent at an outlet of a hydrogenation pretreatment reaction area is controlled to be not higher than 12 microgram/g. After hydrogenation, the sulfur content in the effluent of the hydrotreating reaction zone was 0.20 wt%, the nitrogen content was 1712 mug/g, the carbon residue value was 4.42 wt%, and the metal (Ni + V) content was 7.0 mug/g. After the operation is carried out for 6 months, the content of metal (Ni + V) of effluent at the outlet of the reactor 1 in the first hydrogenation pretreatment reaction zone exceeds 12 mu g/g, or the pressure drop of at least one catalyst bed layer in the reactor 1 reaches the upper pressure drop limit or a hot spot appears in the catalyst bed layer, the effluent is cut out and is cut into the reactor 2 in the second hydrogenation pretreatment reaction zone to continuously finish the hydrotreating process (at the moment, the raw oil A sequentially flows through the reactor 2, the high-pressure separator 5, the hydrogen mixing tank 6, the reactor 3, the hydrogen mixing tank 7 and the reactor 4), the device still stably operates, and the quality of generated oil can meet the feeding requirement of downstream RFCC. When the content of metal (Ni + V) in the effluent at the outlet of the reactor 2 in the second hydrogenation pretreatment reaction zone exceeds 12 mug/g, or the pressure drop of at least one catalyst bed in the reactor 2 reaches the upper pressure drop limit or a hot spot incapable of being continuously operated appears in the catalyst bed, the effluent is cut out, and simultaneously the effluent is cut into the reactor 1 in the first hydrogenation pretreatment reaction zone to continuously complete the hydrogenation treatment process, meanwhile, the catalyst in the reactor 2 in the second hydrogenation pretreatment reaction zone is replaced, and fresh catalyst is filled again for standby. By so circulating, the apparatus was finally operated for 24 months, and shutdown was performed due to deterioration of product quality, during which the reactor 1 and the reactor 2 were charged and discharged with the agent 2 times, respectively.

Comparative example 1

According to the process flow illustrated in fig. 1, the hydrogenation pretreatment reaction area includes a first hydrogenation pretreatment reaction area and a second hydrogenation pretreatment reaction area that are switchable in operation, the first hydrogenation pretreatment reaction area is provided with a reactor 1, the second hydrogenation pretreatment reaction area is provided with a reactor 2, and the hydrogenation treatment reaction area includes a reactor 3 and a reactor 4 that are arranged in series. According to the material flow direction, a hydrogenation pretreatment reaction zone reactor (only one reactor is on-line in the operation process) is filled with a catalyst A, a catalyst B and a catalyst C, and the filling volume ratio of the catalysts is 2: 7: 1. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 1: 9, and the reactor 4 is filled with only a catalyst D.

During the operation, the reaction temperature of the hydrogenation pretreatment reaction zone is lower than that of the hydrotreating zone, and the specific reaction conditions are shown in table 3. Raw oil A sequentially flows through a reactor 1, a high-pressure separator 5, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, and the content of metal (Ni + V) in effluent at the outlet of a hydrogenation pretreatment reaction zone is not controlled. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.22 wt%, the nitrogen content was 1829 mug/g, the carbon residue value was 4.58 wt%, and the metal (Ni + V) content was 8.3 mug/g. After the operation is carried out for 10 months, the pressure drop of at least one catalyst bed layer in the reactor 1 of the first hydrogenation pretreatment reaction zone reaches the upper pressure drop limit or a hot spot appears in the catalyst bed layer, the catalyst bed layer is cut out and is cut into the reactor 2 of the second hydrogenation pretreatment reaction zone to continuously finish the hydrotreating process (at the moment, the raw oil A sequentially flows through the reactor 2, the high-pressure separator 5, the hydrogen mixing tank 6, the reactor 3, the hydrogen mixing tank 7 and the reactor 4), the device still stably operates, and the quality of the generated oil can meet the feeding requirement of the downstream RFCC. After switching reactor 2, the plant was operated for another 8 months, and finally the plant was operated for 18 months with a shutdown due to a deterioration in product quality.

Example 2

According to the process flow described in fig. 2, only one hydrogenation pretreatment reaction area is provided, a reactor 1 is arranged in the hydrogenation pretreatment reaction area, the hydrogenation treatment reaction area comprises a reactor 3 and a reactor 4 which are arranged in series, and the catalyst loading of the hydrogenation pretreatment reaction area accounts for 36% of the total catalyst loading of the device. According to the material flow direction, a hydrogenation pretreatment reaction area reactor 1 is filled with a catalyst A, a catalyst B and a catalyst C, and the filling volume ratio of the three catalysts is 2: 6: 2. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 3: 7, the reactor 4 is filled with the catalyst C and a catalyst D, and the filling volume ratio of the two catalysts is 3: 7. The reactor hydrotreating conditions and test results are listed in table 2.

In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is higher than that of the hydrogenation treatment zone, and the specific reaction conditions are shown in Table 3. The raw oil A sequentially flows through the reactor 1, the reactor 3 and the reactor 4, and the content of metal (Ni + V) in effluent at the outlet of the hydrogenation pretreatment reaction area is controlled to be not higher than 29 mug/g. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.23 wt%, the nitrogen content was 2186 mug/g, the carbon residue value was 4.80 wt%, and the metal (Ni + V) content was 8.7 mug/g. After 12 months of operation, a shutdown was carried out due to a deterioration in product quality, at which point the pressure drop in reactor 1 had reached 85% of the upper pressure drop limit.

Comparative example 2

According to the process flow described in fig. 2, only one hydrogenation pretreatment reaction area is provided, a reactor 1 is arranged in the hydrogenation pretreatment reaction area, the hydrogenation treatment reaction area comprises a reactor 3 and a reactor 4 which are arranged in series, and the catalyst loading of the hydrogenation pretreatment reaction area accounts for 24% of the total catalyst loading of the device. According to the material flow direction, a hydrogenation pretreatment reaction area reactor 1 is filled with a catalyst A and a catalyst B, and the filling volume ratio of the two catalysts is 3: 7. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 3: 7, the reactor 4 is filled with the catalyst C and a catalyst D, and the filling volume ratio of the two catalysts is 2: 8. The hydrotreating conditions and test results are shown in Table 2.

During the operation, the reaction temperature of the hydrogenation pretreatment reaction zone is lower than that of the hydrotreating zone, and the specific reaction conditions are shown in table 3. Raw oil A flows through a reactor 1, a reactor 3 and a reactor 4 in sequence, and the content of metal (Ni + V) in the effluent at the outlet of the hydrogenation pretreatment reaction zone is not controlled. After hydrogenation, the sulfur content in the effluent of the hydrotreating reaction zone is 0.24 wt%, the nitrogen content is 2276 mug/g, the carbon residue value is 4.85 wt%, and the metal (Ni + V) content is 8.8 mug/g. After 12 months of operation, a shutdown was carried out due to a deterioration in product quality, at which point the pressure drop in reactor 1 had reached 85% of the upper pressure drop limit.

Example 3

According to the process flow illustrated in fig. 1, the hydrogenation pretreatment reaction area includes a first hydrogenation pretreatment reaction area and a second hydrogenation pretreatment reaction area that are switchable in operation, the first hydrogenation pretreatment reaction area is provided with a reactor 1, the second hydrogenation pretreatment reaction area is provided with a reactor 2, and the hydrogenation treatment reaction area includes a reactor 3 and a reactor 4 that are arranged in series. According to the material flow direction, a hydrogenation pretreatment reaction zone (only one hydrogenation pretreatment reaction zone is on line in the operation process) is filled with a catalyst A, a catalyst B and a catalyst C, and the filling volume ratio of the catalysts is 3: 6: 1. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 3: 7, the reactor 4 is filled with the catalyst C and a catalyst D, and the filling volume ratio of the two catalysts is 2: 8.

In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is higher than that of the hydrogenation treatment zone, and the specific reaction conditions are shown in Table 3. The raw oil B sequentially flows through the reactor 1, the high-pressure separator 5, the hydrogen mixing tank 6, the reactor 3, the hydrogen mixing tank 7 and the reactor 4, and the content of metal (Ni + V) in effluent at an outlet of a hydrogenation pretreatment reaction area is controlled to be not higher than 20 microgram/g. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.21 wt%, the nitrogen content was 1424 mug/g, the carbon residue value was 3.81 wt%, and the metal (Ni + V) content was 9.5 mug/g. After the operation is carried out for 3 months, the content of metal (Ni + V) of effluent at the outlet of the reactor 1 in the first hydrogenation pretreatment reaction zone exceeds 20 mug/g, or the pressure drop of at least one catalyst bed in the reactor 1 reaches the upper pressure drop limit or a hot spot appears in the catalyst bed, the effluent is cut out and is cut into the reactor 2 in the second hydrogenation pretreatment reaction zone to continuously finish the hydrotreating process (at the moment, raw oil B sequentially flows through the reactor 2, the high-pressure separator 5, the hydrogen mixing tank 6, the reactor 3, the hydrogen mixing tank 7 and the reactor 4), the device still stably operates, and the quality of generated oil can meet the feeding requirement of downstream RFCC. When the content of metal (Ni + V) of effluent at the outlet of the reactor 2 in the second hydrogenation pretreatment reaction zone exceeds 20 mug/g, or the pressure drop of at least one catalyst bed layer in the reactor 2 reaches the upper pressure drop limit or a hot spot incapable of being continuously operated appears in the catalyst bed layer, the effluent is cut out, and simultaneously the effluent is cut into the reactor 1 in the first hydrogenation pretreatment reaction zone to continuously complete the hydrogenation treatment process, meanwhile, the catalyst in the reactor 2 in the second hydrogenation pretreatment reaction zone is replaced, and fresh catalyst is filled again for standby. By so circulating, the apparatus was finally operated for 12 months, and shutdown was performed due to deterioration of product quality, during which the reactor 1 and the reactor 2 were charged and discharged with the agent 2 times, respectively.

Comparative example 3

According to the process flow illustrated in fig. 2, only one hydrogenation pretreatment reaction zone is provided, in which one reactor 1 is disposed, and the hydrogenation treatment reaction zone includes a reactor 3 and a reactor 4 disposed in series. According to the material flow direction, a hydrogenation pretreatment reaction area reactor 1 is filled with a catalyst A and a catalyst B, and the filling volume ratio of the two catalysts is 3: 7. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 5:5, the reactor 4 is filled with the catalyst C and a catalyst D, and the filling volume ratio of the two catalysts is 4: 6. The hydrotreating conditions and test results are shown in Table 2.

In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is lower than that of the hydrogenation treatment zone, and the specific reaction conditions are shown in the following table 3. The raw oil B flows through the reactor 1, the reactor 3 and the reactor 4 in sequence, and the content of metal (Ni + V) in the effluent at the outlet of the hydrogenation pretreatment reaction zone is not controlled. After hydrogenation, the sulfur content in the effluent of the hydrotreating reaction zone is 0.26 weight percent, the nitrogen content is 1687 mug/g, the carbon residue value is 4.23 weight percent, and the metal (Ni + V) content is 15.5 mug/g. After 6 months of operation, a shutdown was carried out due to a deterioration in product quality, at which point the pressure drop in reactor 1 had reached 85% of the upper pressure drop limit.

Example 4

According to the process flow illustrated in fig. 1, the hydrogenation pretreatment reaction area includes a first hydrogenation pretreatment reaction area and a second hydrogenation pretreatment reaction area that are switchable in operation, the first hydrogenation pretreatment reaction area is provided with a reactor 1, the second hydrogenation pretreatment reaction area is provided with a reactor 2, and the hydrogenation treatment reaction area includes a reactor 3 and a reactor 4 that are arranged in series. According to the material flow direction, a hydrogenation pretreatment reaction zone reactor (only one reactor is on-line in the operation process) is filled with a catalyst A, a catalyst B and a catalyst C, and the filling volume ratio of the catalysts is 4: 5: 1. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 1: 9, and the reactor 4 is filled with only a catalyst D.

In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is higher than that of the hydrogenation treatment zone, and the specific reaction conditions are shown in the following table 3. The raw oil C flows through the reactor 1, the high-pressure separator 5, the hydrogen mixing tank 6, the reactor 3, the hydrogen mixing tank 7 and the reactor 4 in sequence, and the content of metal (Ni + V + Fe + Ca) in effluent at an outlet of a hydrogenation pretreatment reaction area is controlled to be not higher than 10 [ mu ] g/g. After hydrogenation, the sulfur content in the effluent of the hydrotreating reaction zone is 0.16 wt%, the nitrogen content is 2292 mug/g, the carbon residue value is 3.52 wt%, the metal (Ni + V) content is 4.8 mug/g, the metal Ca content is 0.5 mug/g, and the metal Fe content is 0.2 mug/g. After the operation is carried out for 4 months, the content of metal (Ni + V + Fe + Ca) in the effluent at the outlet of the reactor 1 in the first hydrogenation pretreatment reaction zone exceeds 10 mug/g or the pressure drop of at least one catalyst bed in the reactor 1 reaches the upper pressure drop limit or a hot spot appears in the catalyst bed, the effluent is cut out and is cut into the reactor 2 in the second hydrogenation pretreatment reaction zone to continuously finish the hydrogenation treatment process (at the moment, the raw oil C sequentially flows through the reactor 2, the high-pressure separator 5, the hydrogen mixing tank 6, the reactor 3, the hydrogen mixing tank 7 and the reactor 4), the device still stably operates, and the quality of the generated oil can meet the feeding requirement of the downstream RFCC. When the content of metal (Ni + V + Fe + Ca) in the effluent at the outlet of the reactor 2 in the second hydrogenation pretreatment reaction zone exceeds 10 mug/g, or the pressure drop of at least one catalyst bed in the reactor 2 reaches the upper pressure drop limit or a hot spot incapable of being continuously operated appears in the catalyst bed, cutting the effluent out, simultaneously cutting in the reactor 1 in the first hydrogenation pretreatment reaction zone to continuously finish the hydrogenation treatment process, simultaneously replacing the catalyst in the reactor 2 in the second hydrogenation pretreatment reaction zone, and reloading a fresh catalyst for standby. By so circulating, the apparatus was finally operated for 16 months, and shutdown was performed due to deterioration of product quality, during which the reactor 1 and the reactor 2 were charged and discharged with the agent 2 times, respectively.

Comparative example 4

According to the process flow illustrated in fig. 2, only one hydrogenation pretreatment reaction zone is provided, in which one reactor 1 is disposed, and the hydrogenation treatment reaction zone includes a reactor 3 and a reactor 4 disposed in series. According to the material flow direction, a hydrogenation pretreatment reaction area reactor 1 is filled with a catalyst A and a catalyst B, and the filling volume ratio of the two catalysts is 4: 6. The hydrotreating reaction zone reactor 3 is filled with a catalyst B and a catalyst C, the filling volume ratio of the two catalysts is 1: 9, the reactor 4 is filled with the catalyst C and a catalyst D, and the filling volume ratio of the two catalysts is 1: 9. The hydrotreating conditions and test results are shown in Table 2.

In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is lower than that of the hydrogenation treatment zone, and the specific reaction conditions are shown in the following table 3. Raw oil C flows through the reactor 1, the reactor 3 and the reactor 4 in sequence, and the content of metal (Ni + V + Fe + Ca) in the effluent at the outlet of the hydrogenation pretreatment reaction zone is not controlled. After hydrogenation, the sulfur content in the effluent of the hydrotreating reaction zone is 0.21 wt%, the nitrogen content is 2936 mug/g, the carbon residue value is 3.98 wt%, the metal (Ni + V) content is 6.3 mug/g, the metal Ca content is 1.8 mug/g, and the metal Fe content is 0.5 mug/g. After 8 months of operation, the plant was forced to shut down as the pressure drop across reactor 1 reached the upper pressure drop limit.

TABLE 3 conditions of hydrotreatment and test results

	Example 1	Comparative example 1	Example 2	Comparative example 2
					Raw oil	Raw oil A	Raw oil A	Raw oil A	Raw oil A
Preprocessing region mode of operation	Handover	Handover	Not switching over	Not switching over
					Process conditions
Partial pressure of hydrogen, MPa	14.5	14.5	14.5	14.5
					Reaction temperature of
Reactor 1	390	373	385	373
					Reactor 2	390	373
Reactor 3	372	376	375	379
					Reactor 4	376	383	378	385
CAT	378	378	380	380
					Volume space velocity of the hydrotreatment zone, h^-1	0.83	0.83	0.56	0.83
Volumetric space velocity, h, of the hydrotreating zone^-1	0.40	0.40	0.31	0.26
					Hydrogen to oil volume ratio, Nm, in the hydrotreatment zone³/m³	700	700	700	700
Liquid phase recycle ratio of hydrotreating zone%	0.6:1	0.6:1	-	-
					The reaction produces oily substances
Sulfur, wt.%	0.20	0.22	0.23	0.24
					Nitrogen,. mu.g/g	1712	1829	2186	2276
Carbon residue, by weight%	4.42	4.58	4.80	4.85
					Nickel + vanadium, μ g/g	7.0	8.3	8.7	8.8
Calcium, μ g/g
					Iron,. mu.g/g
Operating cycle of month	24	18	12	12
					Number of times of filling the reactor 1	2	1	1	1
Number of times of filling agent in reactor 2	2	1	-	-
					Number of times of filling reactors 3 and 4	1	1	1	1

TABLE 3 hydrotreating conditions and test results

	Example 3	Comparative example 3	Example 4	Comparative example 4
					Raw oil	Raw oil B	Raw oil B	Raw oil C	Raw oil C
Preprocessing region mode of operation	Handover	Not switching over	Handover	Not switching over
					Process conditions
Partial pressure of hydrogen, MPa	14.5	14.5	14.5	14.5
					Reaction temperature of
Reactor 1	390	380	386	373
					Reactor 2	390		386
Reactor 3	374	384	375	378
					Reactor 4	378	389	377	382
CAT	380	385	378	378
					Volume space velocity of the hydrotreatment zone, h^-1	0.71	0.83	0.89	0.83
Volumetric space velocity, h, of the hydrotreating zone^-1	0.60	0.26	0.52	0.26
					Hydrogen in a hydrogen pretreatment zoneOil volume ratio, Nm³/m³	700	700	700	700
Liquid phase recycle ratio of hydrotreating zone%	1:1		1:1
					The reaction produces oily substances
Sulfur, wt.%	0.21	0.26	0.16	0.21
					Nitrogen, microgram/g	1424	1687	2292	2936
Carbon residue, by weight%	3.81	4.23	3.52	3.98
					Nickel + vanadium, microgram/g	9.5	15.5	4.8	6.3
Calcium, microgram/g			0.5	1.8
					Iron, microgram/g			0.2	0.5
Operating cycle of month	12	6	16	8
					Number of times of filling the reactor 1	2	1	2	1
Number of times of filling agent in reactor 2	2	-	2	-
					Number of times of filling reactors 3 and 4	1	1	1	1

To further examine the effect of the process technology of the present invention on the hydroprocessing reaction zone catalyst, catalyst C and catalyst D were analyzed after running example 1, comparative example 1, example 2 and comparative example 2, respectively, and the results are shown in tables 4 and 5.

TABLE 4 catalyst C analysis results before and after operation

	Specific surface area, m²·g^-1	Pore volume, cm³·g^-1	Average pore diameter, nm	Carbon deposition amount, g/100mL	Amount of deposited metal, g/100mL
						Fresh agent	180.0	0.55	12.2	-	-
Inactivating agent
						Example 1	110.2	0.20	7.3	20.16	-
Comparative example 1	115.2	0.22	7.6	18.38	-
						Example 2	124.1	0.29	9.3	10.26	-
Comparative example 2	125.2	0.28	8.9	12.31	-
						Regenerant
Example 1	167.6	0.49	11.7	0.09	1.11
						Comparative example 1	147.5	0.40	10.8	0.21	5.36
Example 2	170.1	0.50	11.8	0.12	2.23
						Comparative example 2	145.3	0.38	10.5	0.26	6.11

TABLE 5 catalyst D analysis results

	Specific surface area, m²·g^-1	Pore volume, cm³·g^-1	Average pore diameter, nm	Carbon deposition amount, g/100mL	Amount of deposited metal, g/100mL
						Fresh agent	225.0	0.48	8.5	-	-
Inactivating agent
						Example 1	117.7	0.16	5.4	26.14	-
Comparative example 1	122.6	0.17	5.5	24.53	-
						Example 2	129.2	0.21	6.5	15.36	-
Comparative example 2	130.1	0.20	6.1	18.24	-
						Regenerant
Example 1	214.8	0.44	8.2	0.18	0.79
						Comparative example 1	204.5	0.40	7.8	0.35	3.44
Example 2	217.2	0.45	8.3	0.22	1.45
						Comparative example 2	188.4	0.36	7.6	0.44	4.10

From the above analysis, it can be seen that by changing the catalyst system and operation mode, i.e. changing the prior art to the trend of low front and high back according to the reaction temperature in the material flow direction (comparative example 2) and the trend of high front and low back according to the reaction temperature in the material flow direction (example 2), the activity of all the catalysts can be fully utilized while ensuring the product quality, and as most of the metal impurities in the material are removed in the hydrogenation pretreatment reaction zone, the inactivation reason of the desulfurization catalyst and/or the denitrification catalyst in the hydrogenation treatment reaction zone is changed from the metal deposition and the carbon deposition inactivation by the prior art to the carbon deposition inactivation only, the utilization rate of the desulfurization catalyst and/or the denitrification catalyst is effectively improved, and simultaneously, the desulfurization catalyst and the denitrification catalyst can be regenerated after being used for one cycle and reused, the method saves the catalyst purchase cost, improves the economy, has more obvious advantages after the hydrogenation pretreatment reaction zone carries out switchable operation (embodiment 1), and can greatly increase the operation period of the device.

In addition, because the sulfur content, the carbon residue value and the metal content in the product of the process technology are lower than those of the prior process technology, the product quality of a downstream RFCC device is positively influenced, and the metal content in the RFCC feeding is reduced, so that the catalyst consumption of the RFCC device can be greatly reduced, and extra economic benefits are brought to enterprises.

Claims

1. A heavy oil hydrotreating method for improving catalyst utilization rate comprises the following steps:

(1) providing at least one hydrotreating reaction zone and at least one hydrotreating reaction zone; the hydrogenation pretreatment reaction zone comprises a hydrogenation protection catalyst and a hydrogenation demetalization catalyst, and the hydrogenation treatment reaction zone comprises a hydrogenation desulfurization catalyst and a hydrogenation denitrification catalyst;

(4) mixing the liquid product obtained in the step (3) with part of material flow recycled in the hydrotreating area, feeding the mixture into a hydrogen mixing tank for hydrogen mixing, feeding the mixed oil after saturated hydrogen dissolution into a liquid phase hydrotreating reactor, and carrying out contact reaction with a catalyst under the hydrotreating condition to obtain a liquid phase effluent with reduced sulfur content and nitrogen content;

(5) circulating one part of the liquid phase effluent obtained in the step (4) to a hydrogen mixing tank, and discharging the other part of the liquid phase effluent out of the device after pressure reduction;

the average reaction temperature of the hydrogenation pretreatment reaction zone in the step (2) is 5-40 ℃ higher than that of the hydrogenation treatment reaction zone in the step (4).

2. The process of claim 1 wherein the average reaction temperature in the hydrotreating reaction zone in step (2) is from 10 ℃ to 30 ℃ higher than the average reaction temperature in the hydrotreating reaction zone in step (4).

3. The process of claim 1 wherein the hydrotreating reaction zone contains a hydrodesulfurization catalyst in an amount of from 0v% to 30v% of the catalyst loading in the pretreatment reaction zone.

4. The process according to claim 3, wherein the hydrodesulfurization catalyst is disposed downstream of the hydrogenation protection catalyst and the hydrodemetallization catalyst in the order of contact with the feedstock in the hydrogenation pretreatment reaction zone.

5. The process of claim 3 wherein the hydroprocessing reaction zone contains a hydrodemetallization catalyst, and the loading of the hydrodemetallization catalyst is from 5v% to 30v% of the loading of the catalyst in the hydroprocessing reaction zone.

6. The method according to claim 5, wherein the hydrodemetallization catalyst is packed upstream of the hydrodesulfurization catalyst and the hydrodenitrogenation catalyst in the order of contact with the material.

7. The method according to claim 1, wherein more than two hydrogenation pretreatment reaction zones are provided in step (1), and the more than two hydrogenation pretreatment reaction zones are arranged in parallel and are switchable in operation.

8. The method of claim 7, further comprising the step (6) of, when one of the hydrotreating reaction zones fails to meet the operational requirements, short-circuiting it, cutting out the reaction flow, and cutting a second hydrotreating reaction zone into the process flow, the cut-out hydrotreating reaction zone performing catalyst replacement, i.e., discharging the deactivated old catalyst and recharging with fresh and/or regenerated catalyst; and when the cut-in second hydrogenation pretreatment reaction area can not meet the operation requirement, cutting the hydrogenation pretreatment reaction area subjected to catalyst replacement into the process flow, and short-circuiting and cutting out the second hydrogenation pretreatment reaction area to perform catalyst replacement.

9. The method of claim 8, wherein the failure of the hydroprocessing pretreatment reaction zone to meet operational requirements is: the effluent of the hydrogenation pretreatment reaction zone cannot meet the feeding requirement of a downstream hydrogenation treatment zone, or the pressure drop of at least one catalyst bed layer in the hydrogenation pretreatment reaction zone reaches the upper limit of the pressure drop, or hot spots appear in the catalyst bed layers.

10. The process of claim 9 wherein the criteria that fails to meet the feed requirements of the downstream hydroprocessing reaction zone are: the metal content in the effluent liquid of the hydrogenation pretreatment reaction area exceeds any numerical value between 8 mug/g and 50 mug/g; the upper limit of the pressure drop is 0.4-0.8 times of the maximum pressure drop designed by the reactor; the hot spot means that the radial temperature difference in at least one catalyst bed layer reaches 15-50 ℃.

11. The method of claim 1, wherein the heavy oil feedstock is selected from the group consisting of high asphaltene content hydrocarbons obtained from topped crude oil, petroleum residuum, oil sands, bitumen, shale oil, liquefied coal, or reclaimed oil; the metal content of the heavy oil raw oil is more than 30 mug/g.

12. The method according to claim 11, characterized in that the content of nickel and vanadium in the heavy oil raw oil is more than 60 mug/g, the content of iron is more than 10 mug/g, and/or the content of calcium is more than 10 mug/g.

13. The process of claim 1, wherein the hydrodemetallization catalyst has the properties that, based on the total weight of the catalyst, the content of molybdenum and/or tungsten in terms of oxides is 0.5 to 15 wt.%, the content of cobalt and/or nickel is 0.3 to 8 wt.%, and the balance is an alumina support; the alumina carrier is bimodal porous alumina, the pore volume of the alumina carrier is 0.5-2.0 ml/g, and the specific surface area of the alumina carrier is 120-350 m²And/g, the pore volume of the pore diameter of 10-30 nm accounts for 30-90% of the total pore volume, the pore volume of the pore diameter of 100-2000 nm accounts for 10-50% of the total pore volume, and the sum of the pore volumes of the pore diameters of less than 10 nm, between 30-100 nm and more than 2000 nm accounts for less than 20% of the total pore volume.

14. The method according to claim 1, wherein the loading volume ratio of the hydrogenation protection catalyst to the hydrodemetallization catalyst in the hydrogenation pretreatment reaction zone is 5:95 to 95: 5.

15. The process of claim 1 wherein the hydrodesulfurization catalyst is loaded in the hydrotreating reaction zone in an amount of from 5v% to 30v% of the loading of the hydrodemetallization catalyst.

16. The process of claim 1 wherein the hydrodesulfurization catalyst comprises from 10 to 25 wt.% molybdenum and/or tungsten, calculated as oxides, 1 to 6 wt.% cobalt and/or nickel, and the balance being an alumina support, based on the total weight of the catalyst.

17. The process according to any one of claims 1 to 2, wherein the reaction conditions in the hydrogenation pretreatment reaction zone are such that the reaction pressure is from 5MPa to 35MPa, the average reaction temperature is from 340 ℃ to 430 ℃ and the liquid hourly space velocity is 0.1 hr^-1～5.0h^-1The volume ratio of hydrogen to oil is 200-2000.

18. The method according to claim 1, wherein the loading volume ratio of the hydrodesulfurization catalyst to the hydrodenitrogenation catalyst in the hydrotreating reaction zone is 20:80 to 80: 20.

19. The process according to any one of claims 1 to 2, wherein the reaction conditions in the hydrotreating reaction zone are a reaction pressure of 5MPa to 35MPa, an average reaction temperature of 320 ℃ to 420 ℃ and a liquid hourly space velocity of 0.1 hr^-1～5.0h^-1The liquid phase circulation mass ratio is 0.1: 1-10: 1.

20. The process of claim 1 wherein the hydrotreating reaction zone is provided with one or more hydroprocessing reactors each having at least one hydroprocessing catalyst bed.