Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for treating inferior residual oil by a combined process, in particular to a heavy oil treatment combined method which can give full play to the performances of catalysts in different reaction zones and increase the running period of a device.
The method for treating the inferior residual oil by the combined process comprises the following steps:
(1) providing at least one hydrotreating reaction zone, and one catalytic cracking reaction zone; the hydrogenation pretreatment reaction zone comprises a hydrogenation protection catalyst and a hydrogenation demetalization catalyst, the hydrogenation treatment reaction zone comprises a hydrodesulfurization catalyst and a hydrodenitrogenation (carbon residue conversion) catalyst, and the catalytic cracking reaction zone comprises a catalytic cracking catalyst;
(2) poor raw oil, circulating oil in a hydrotreating area, catalytic cracking slurry oil, part of catalytic cracking cycle oil and hydrogen enter a mixer together to form a saturated hydrogen-dissolved material flow;
(3) the saturated hydrogen-dissolved material flow from the step (2) enters a hydrogenation pretreatment reaction zone, liquid-phase hydrogenation reaction is carried out under the condition of hydrogenation pretreatment, 40-90 wt% of metal impurities are removed, 20-70 wt% of sulfur is removed, and reaction effluent with reduced metal content is obtained;
(4) mixing the reaction effluent obtained in the step (3) with part of the catalytic cracking cycle oil without separation, then feeding the mixture into a hydrogen mixing tank, feeding the mixed oil after saturated hydrogen dissolution into a liquid phase hydrotreating reactor, and carrying out hydrogenation reaction under the hydrotreating condition to obtain the reaction effluent with reduced sulfur content and nitrogen content;
(5) recycling one part of the liquid phase hydrogenation reaction effluent obtained in the step (4) to the hydrogenation pretreatment reaction area, and allowing the other part of the liquid phase hydrogenation reaction effluent to enter a separator for gas-liquid separation to obtain hydrogen-rich gas and first liquid; leading out the hydrogen-rich gas obtained by separation from a device, and leading the first liquid product obtained by separation into a fractionation system;
(6) the first liquid product obtained by the separation in the step (5) enters a fractionating tower to obtain gas, naphtha, hydrogenated diesel oil and hydrogenated tail oil;
(7) the hydrogenated tail oil obtained in the step (6) enters a catalytic cracking reaction zone, a cracking reaction is carried out in the presence of a catalytic cracking catalyst, and the oil generated in the reaction is fractionated to obtain dry gas, liquefied gas, catalytic cracking gasoline, catalytic cracking diesel oil, catalytic cracking cycle oil and catalytic cracking slurry oil;
(8) and (4) separating the catalytic cracking recycle oil from the step (7) into two parts, wherein one part is mixed with the catalytic cracking slurry oil to be used as diluent oil and is circulated back to the hydrogenation pretreatment reaction zone, and the other part is circulated back to the hydrogen mixing tank of the hydrogenation treatment reaction zone to be subjected to hydrogen mixing.
The method according to the present invention, wherein the step (8) may further include the following steps: recycling at least one part of the catalytic cracking diesel oil obtained in the step (7) to the second hydrogen mixing tank of the hydrotreating reaction zone.
Wherein the average reaction temperature t1 of the hydrogenation pretreatment reaction zone in the step (3) is higher than the average reaction temperature t2 of the hydrogenation treatment reaction zone in the step (4), preferably t1 is 5-40 ℃ higher than t2, and more preferably t1 is 10-30 ℃ higher than t 2.
In the present invention, it is preferable to provide two or more hydrogenation pretreatment reaction zones in step (1), and the two or more hydrogenation pretreatment reaction zones are usually reaction zones which are arranged in parallel and can be switched in operation. Therefore, the method of the present invention may further comprise a step (9) 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 criterion for judging whether the liquid product at the outlet of the hydrogenation pretreatment reaction zone meets the feeding requirement of a downstream hydrogenation treatment zone is that the metal content (the sum of the contents of Ni, V, Fe, Na, Ca and the like) in the effluent liquid exceeds 8-50 mu g/g, preferably 10-30 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 layer is 15-50 ℃, and preferably 15-30 ℃.
In the method, the heavy oil raw oil refers to hydrocarbons with high asphaltene content obtained from topped crude oil, petroleum residual oil, oil sand, asphalt, shale oil, liquefied coal or reclaimed oil. The heavy oil raw oil usually 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 of more than 60mg/g and/or iron content of more than 10mg/g and/or calcium content of more than 10 mg/g.
In the method of the present invention, the hydrogenation protection catalyst used in the hydrogenation pretreatment reaction zone can be a residual oil hydrogenation protective agent, or can be prepared according to the material properties by the conventional method in the field. 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 porous refractory inorganic oxide such as alumina as a carrier and oxides of metals in VIB group and/or VIII group such as W, Mo, Co, Ni and the like as active components, for example, FZC series residual oil hydrogenation protective agent produced by catalyst division of China petrochemical industry Co.
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 catalysts in which a porous refractory inorganic oxide such as alumina is used as a carrier, one or more oxides of metals of 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. 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 a bimodal-pore alumina carrier, 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. 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 hydrogenation pretreatment reaction zone preferably comprises a hydrodemetallization catalyst and a hydrodesulfurization catalyst downstream of the hydrodemetallization catalyst. The loading amount of the hydrodesulfurization catalyst is 5-30% of that 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 limited, the improved hydrodesulfurization catalyst is optimized and 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 generally 0.1h-1~5.0h-1Preferably 0.3h-1~3.0h-1In the range of (1), the liquid phase circulation ratio (mass ratio of the circulating oil to the fresh raw oil) is 0.1:1 to 10:1, preferably 0.2:1 to 3: 1.
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, circulating oil saturated with dissolved hydrogen can be injected between the reaction bed layers, so that the aims of reducing the temperature rise of the catalyst bed layers and supplementing hydrogen required by reaction in time are fulfilled.
The mixer used in the process of the present invention may be a vortex mixer, a static mixer, a jet mixer or the like.
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 is based on the total weight of the catalyst, and calculated by oxides, the content of molybdenum and/or tungsten is 12-30 wt%, the content of cobalt and/or nickel is 3-12 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 40-75% of the total pore volume.
The method of the invention can also comprise a hydrodemetallization catalyst in the hydrotreating reaction zone, wherein the hydrodemetallization catalyst is filled at the upstream of the hydrodesulfurization catalyst, and the filling amount of the hydrodemetallization catalyst is 2-30% 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 hydrogenation pretreatment 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 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, a hydrodesulfurization catalyst and a hydrodenitrogenation catalyst are sequentially filled along the flow direction of a reactant flow. 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 method 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, and therefore, the number of reactors and the connection relationship of the reactors provided for each hydrotreating reaction zone are only required to satisfy the purpose of switching. 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 method, the catalytic cracking recycle oil and the catalytic cracking slurry oil entering the hydrotreating reaction zone and the hydrotreating pretreatment reaction zone can be the catalytic cracking recycle oil and the catalytic cracking slurry oil obtained in the catalytic cracking reaction zone in the method, and can also comprise the catalytic cracking recycle oil and the catalytic cracking slurry oil obtained in other catalytic cracking devices. In the method, part of the catalytic cracking recycle oil obtained from the catalytic cracking reaction zone is circulated to the first hydrogen mixing tank of the hydrotreating reaction zone, the other part of the catalytic cracking recycle oil is mixed with the catalytic cracking oil slurry and then circulated to the hydrotreating pretreatment reaction zone, the recycle oil circulated to the first hydrogen mixing tank of the hydrotreating reaction zone accounts for more than 10 percent, preferably 20-50 percent of the weight of the catalytic cracking recycle oil obtained from the catalytic cracking reaction zone, the recycle oil circulated to the hydrotreating pretreatment reaction zone accounts for more than 10 percent, preferably 20-50 percent of the weight of the catalytic cracking recycle oil obtained from the catalytic cracking reaction zone, the total amount of the recycle oil circulated to the first hydrogen mixing tank of the hydrotreating reaction zone and the recycle oil circulated to the hydrotreating pretreatment reaction zone generally accounts for at least 20 percent, preferably 30-95 percent of the weight of the catalytic cracking recycle oil obtained from the catalytic cracking reaction zone, and the rest part of the catalytic cracking recycle oil is circulated to the catalytic cracking reaction zone. And circulating the catalytic cracking slurry oil obtained from the catalytic cracking reaction zone to the hydrogenation pretreatment reaction zone, wherein the catalytic cracking slurry oil circulated to the hydrogenation pretreatment reaction zone generally accounts for at least more than 30% of the catalytic cracking slurry oil obtained from the catalytic cracking reaction zone, preferably 50-80%, and the rest catalytic cracking slurry oil is discharged outside.
The method according to the invention can further comprise the following steps: the catalytic cracking diesel oil can be wholly or partially recycled to the second hydrogen mixing tank of the hydrotreating reaction zone. The catalytic cracking diesel oil circulated to the hydrotreating reaction zone generally accounts for at least 10% of the weight of the catalytic cracking diesel oil fraction obtained in the catalytic cracking reaction zone, preferably 20-80%, and the rest part of the catalytic cracking diesel oil can be circulated to the catalytic cracking reaction zone or discharged as a product as required. Preferably, the method also comprises a process of cutting the catalytic cracking diesel into light fraction and heavy fraction, wherein the cutting temperature is 245-300 ℃. The heavy fraction is introduced into a hydrogen mixing tank before the last reactor of the hydrotreating reaction zone, and the light fraction is introduced into the middle of the last reactor of the hydrotreating reaction zone.
In the method, if solid impurities exist in the catalytic cracking cycle oil and the catalytic cracking slurry oil, the solid impurities can be further removed and recycled. The content of the solid impurities in the catalytic cracking cycle oil and the catalytic cracking slurry oil with the solid impurities removed is less than 30 mu g/g, preferably less than 15 mu g/g, and more preferably less than 5 mu g/g.
In the method of the invention, the catalytic cracking device can be one set or more than one set, each set of device at least comprises a reactor and a regenerator, the catalytic cracking device is provided with a fractionating tower, each set of catalytic cracking device can be respectively provided with a fractionating tower, and the fractionating towers can also be shared. The fractionating tower fractionates the catalytic cracking reaction effluent into dry gas, liquefied gas, catalytic cracking gasoline, catalytic cracking diesel oil, catalytic cracking cycle oil, catalytic cracking slurry oil and the like, and the fractionation point of each fraction can be specifically determined according to the requirement.
In the process of the present invention, the operating conditions of the catalytic cracking reaction zone are generally: the reaction temperature is 470-650 ℃, the reaction time is 0.5-5 seconds, the weight ratio of the catalyst to the raw oil is 3-10, and the catalyst regeneration temperature is 650-800 ℃. The catalytic cracking reactor is typically a riser reactor, or a riser and bedCombining the layer reactors. The catalytic cracking catalyst comprises zeolite, inorganic oxide and optional clay, and the weight contents of the components are respectively as follows: 5-50% of zeolite, 5-95% of inorganic oxide and 0-70% of clay. The zeolite can be one or more selected from Y-type zeolite, rare earth Y-type zeolite (REY), rare earth hydrogen Y-type zeolite (REHY), ultrastable Y-type zeolite (USY), ZSM series zeolite and ZRP zeolite. Inorganic oxide as binder selected from silicon dioxide (SiO)2) And/or aluminum trioxide (AL)2O3). The clay is selected from kaolin and/or halloysite as a matrix, i.e., a carrier.
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 a residual oil hydrotreater is shut down due to hot spots and/or pressure drop of a hydrogenation protection catalyst bed, a desulfurization catalyst and a denitrification catalyst used at the rear part (downstream) of the hydrotreater are also deactivated, but the deactivation is more caused by that the openings of catalyst channels are blocked by deposited metal, and the deposited metal in the catalyst channels is not much. Specifically analyzing the reason, the applicant believes that: in the middle and later period of the residual oil hydrogenation device operation, the metal in the raw oil penetrates through the hydrogenation protection catalyst and the demetalization catalyst bed layer and directly enters the rear desulfurization catalyst and denitrification catalyst bed layer. 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 caused by the carbon deposition of the catalyst itself, but is caused by the fact that the desulfurization and/or denitrification catalyst, which should have a more hydrodesulfurization and/or denitrification function, assumes the hydrodemetallization function after the feedstock oil has penetrated 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 residual oil hydrogenation apparatus into a hydrogenation pretreatment reaction zone operating at a relatively high reaction temperature and a hydrotreating reaction zone operating 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 catalyst system and the operation mode of the existing residual oil hydrogenation device, namely, the reaction temperature in the prior art shows the trend of low front and high back according to the material flow direction, and the reaction temperature in the material flow direction shows the trend of high front and low back. The inventors of the present invention have completed the present invention on this basis.
In the prior art, a technical scheme for recycling catalytic cracking cycle oil to a residual oil hydrogenation device is provided. However, the present inventors have found through research that the incorporation of a small amount of catalytic cracking cycle oil into a residual oil feed can reduce the viscosity of the residual oil feed and promote the impurity removal reaction of the residual oil. However, with the increase of the doping proportion of the catalytic cracking recycle oil, when the viscosity of the feeding material of the residual oil hydrogenation device is reduced to a certain degree, the doping proportion of the catalytic cracking recycle oil is continuously increased, and the promotion effect on the residual oil hydrogenation impurity removal reaction is not increased any more. Meanwhile, the residual oil contains a large amount of heavy metals such as Ni and V, so that the residual carbon value is high, the asphaltene is high, and the hydrogenation effect of the catalytic cracking recycle oil can be seriously influenced. Therefore, the catalytic cracking cycle oil is divided into two parts, one part is used as diluent oil of residual oil raw materials, and the other part is recycled to the hydrotreating area to be mixed with reaction effluent of the hydrotreating area and then is hydrotreated at higher hydrogen partial pressure and lower reaction temperature. Therefore, the purposes of reducing the viscosity of the residual oil raw material and promoting the residual oil hydrogenation impurity removal reaction can be achieved, meanwhile, the hydrofining of the catalytic cracking cycle oil can be realized, and the effect of the hydrogenation of the catalytic cracking cycle oil can be improved. In addition, the low-temperature-level catalytic cracking recycle oil is circulated to the hydrotreating area, so that the temperature of the high-temperature-level reaction effluent in the hydrotreating area can be adjusted, the reaction temperature in the hydrotreating area can be controlled, and the investment on equipment such as a heat exchanger can be saved.
In contrast to distillate hydrotreaters, residue hydrotreaters typically deposit significant amounts of carbon on the catalyst bed at the back and more carbon near the reactor outlet. The reason is that the colloid and oil components have high hydrogenation saturation speed, the asphaltene has low hydrogenation saturation speed, side chains are easy to break, and only aromatic nuclei with extremely high aromaticity remain, so that the solubility of the colloid and oil components in an environment solvent with higher and higher saturation is smaller and smaller, and finally the colloid and oil components are easy to deposit on a catalyst to form carbon deposit. After the catalytic cracking recycle oil is added, the peptization capacity of the surrounding solvent to the asphaltene can be improved, the deposition of the surrounding solvent on the rear catalyst is reduced, and the service life of the catalyst is prolonged. In addition, partial hydrogenation products of polycyclic aromatic hydrocarbons in the catalytic cracking recycle oil are strong hydrogen donors, can reduce condensation of residual oil thermal free radicals and inhibit generation of coking precursors. These can greatly reduce the carbon deposit of the catalyst, reduce the deactivation rate and prolong the operation period.
Compared with the prior art, the method has the following advantages:
1. the heavy oil hydrotreatment device is divided into a hydrogenation pretreatment reaction area and a hydrotreating reaction area, and 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, and the activity of all the catalysts in the hydrotreating area can be fully utilized. Compared with the prior art, the whole operation period of the device can be prolonged by 30-100%, so that the operation 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, the raw material with higher metal content can be processed, and the raw material source is widened.
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 whole device adopts liquid phase hydrogenation, on one hand, the purpose of reducing the temperature rise of a catalyst bed is achieved, the generation of hot spots can be effectively avoided, meanwhile, the injection amount of quench hydrogen between beds and/or between reactors is greatly reduced, on the other hand, part of aromatic hydrocarbon is saturated through hydrogenated circulating oil, the device has a hydrogen supply function, coke formation can be inhibited, carbon deposition and inactivation of the catalyst are avoided, and the service life of the catalyst is further prolonged.
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. The low-temperature-level catalytic cracking cycle oil is circulated to the hydrotreating area, so that the temperature of the high-temperature-level reaction effluent in the hydrotreating area can be adjusted, the reaction temperature in the hydrotreating area can be controlled, and the investment on equipment such as a heat exchanger can be saved.
6. The catalytic cracking recycle oil and the catalytic cracking slurry oil are respectively circulated to the hydrogenation pretreatment area and the hydrogenation treatment area, so that impurities can be removed in the hydrogenation process, aromatic hydrocarbon is saturated, the catalytic cracking raw material composition is better, and the catalytic cracking high additional product yield is further improved.
7. In the method, the catalytic cracking slurry oil and part of the catalytic cracking cycle oil are used as diluent oil to be circulated to the inlet of the hydrogenation pretreatment area, so that the viscosity of the residual oil raw material can be reduced, the material flow distribution and mass transfer of the raw material in a reactor can be improved, the influence of diffusion in the residual oil hydrogenation treatment process can be reduced, the deposition distribution of metals such as nickel, vanadium and the like in a reaction system can be improved, and the service life of the catalyst can be prolonged. The catalytic cracking recycle oil is circulated to the hydrogenation pretreatment area and the hydrogenation treatment area, so that the peptization capacity of surrounding solvents to the asphaltenes can be improved, the deposition of the surrounding solvents on a rear catalyst is reduced, and the service life of the catalyst is prolonged. In addition, partial hydrogenation products of polycyclic aromatic hydrocarbons in the catalytic cracking recycle oil are strong hydrogen donors, can reduce condensation of residual oil thermal free radicals and inhibit generation of coking precursors. These can greatly reduce the carbon deposit of the catalyst, reduce the deactivation rate and prolong the operation period.
8. In the method, the catalytic cracking diesel oil is circulated to the hydrogen mixing tank in front of the last reactor of the hydrotreating reaction zone, and the lower reaction temperature of the hydrotreating reaction zone is favorable for the saturation of aromatic hydrocarbon in the catalytic cracking diesel oil; the hydrogenation depth of the last reactor of the hydrotreating reaction zone can be controlled by adjusting the circulating amount of the catalytic cracking diesel.
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 principle flow diagram of the method for treating the inferior residual oil by the combined process provided by the invention, and a plurality of necessary devices (a heating furnace, a heat exchanger, a pump, a valve and the like) are omitted in the drawing.
The process of the method for treating the inferior residual oil by the combined process provided by the invention comprises the following steps:
first the fresh feedstock residuum from line 8, the catalytically cracked recycle oil and catalytically cracked slurry oil from line 42, fresh hydrogen from line 23, and the hydrotreated product recycle oil recycled via line 21 are passed together into mixer 5 to form a saturated hydrogen-dissolved stream. The saturated hydrogen-dissolved stream enters reactor 1 of the first hydrogenation pretreatment reaction zone via line 24 and line 10, and undergoes hydrodesulfurization and hydrodemetallization in the presence of a catalyst. The hydrogenated product flows out from the top of the reactor 1 in the first hydrogenation pretreatment reaction zone, is mixed with the catalytic cracking recycle oil from the pipeline 41 through the pipeline 9, enters the hydrogen mixing tank 6, is mixed with the hydrogen introduced through the pipeline 15 to dissolve the hydrogen, the surplus hydrogen is discharged through the pipeline 14, and the mixed oil after saturated hydrogen dissolution enters the liquid phase hydrogenation reactor 3 through the pipeline 16 to carry out the hydrogenation reaction. The reaction effluent enters a hydrogen mixing tank 7 through a pipeline 17, is mixed with hydrogen introduced through a pipeline 19 to dissolve hydrogen, surplus hydrogen is discharged through a pipeline 18, and the mixed oil after saturated hydrogen dissolution enters a liquid phase hydrogenation reactor 4 through a pipeline 20 to carry out a hydrotreating reaction. One part of the obtained reaction effluent is circulated back to the hydrogenation pretreatment area through a pipeline 21, the other part of the obtained reaction effluent enters a separator 25 through a pipeline 22 for gas-liquid separation, the hydrogen-rich gas obtained by separation is extracted through a pipeline 26, the first liquid obtained by separation is extracted through a pipeline 27 and enters a fractionating tower 28 for separation, and gas, naphtha, hydrogenated diesel oil and residual oil hydrogenated tail oil are obtained and are respectively extracted through a pipeline 29, a pipeline 30, a pipeline 31 and a pipeline 32.
The residual oil from the line 32 enters a catalytic cracking reaction zone 33, and is subjected to cracking reaction in the presence of a catalytic cracking catalyst, and the oil gas after the reaction is fractionated to obtain gas, catalytic gasoline, catalytic cracking diesel oil, catalytic cracking recycle oil and catalytic cracking slurry oil. Dry gas, liquefied gas and catalytic gasoline are discharged from the device through pipelines 34, 35 and 36 respectively. The catalytic cracking diesel oil is recycled back to the catalytic cracking reaction zone through a pipeline 37 or discharged as a product according to requirements. The catalytic cracking recycle oil is divided into two parts, one part is mixed with the catalytic cracking slurry oil through a pipeline 38 and a pipeline 40 to be used as diluent oil, the diluent oil is mixed with fresh raw material residual oil from a pipeline 8, new hydrogen from a pipeline 23 and cycle oil from a hydrotreating zone of a pipeline 21 through a pipeline 42 to enter a mixer 5 to form a saturated hydrogen-dissolved material flow, and the other part is recycled to a hydrogen mixing tank 6 of a hydrotreating reaction zone through a pipeline 38 and a pipeline 41.
FIG. 2 is another schematic flow diagram of the method for treating inferior residual oil by a combined process of the present invention, which is different from FIG. 1 in that the catalytically cracked diesel oil is recycled to the hydrogen mixing tank 7 before the hydrotreating zone reactor 4 through a line 37.
When the reactor 1 of 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 is cut into the reactor 2 of the second hydrogenation pretreatment reaction zone through a pipeline 12 to continuously complete the hydrogenation treatment process, and simultaneously the catalyst in the reactor 1 of 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. The catalytic cracking catalysts used in the examples and comparative examples were the same as those used in a 350-ten-thousand-ton/year heavy oil catalytic cracking apparatus, a petrochemical company, and are industrial equilibrium catalysts. The fresh agent comprises the following components: 95wt% LBO-16 olefin reducing catalyst +5wt% LBO-A octane number enhancing adjuvant.
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, the specific reaction conditions and the residual oil hydrogenation reaction result are shown in table 3, the catalytic cracking operation conditions are shown in table 5, and the distribution of catalytic cracking products and the properties of catalytic cracking gasoline are shown in table 6. Raw oil A sequentially flows through a mixer 5, a reactor 1, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, one part of reaction effluent is circulated to the mixer 5 (the circulation ratio is 0.3: 1), the other part of reaction effluent enters a catalytic cracking reaction zone after gas-liquid separation and fractionation, 40% of all catalytic cracking oil slurry and all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to the mixer 5, 40% of all catalytic cracking recycle oil in the catalytic cracking reaction zone is circulated to a hydrotreating reaction zone hydrogen mixing tank 6, catalytic cracking diesel oil is directly discharged out of the device, and the content of metal (Ni + V) in the effluent at the outlet of the hydrotreating pretreatment reaction zone is controlled to be not higher than 12 mu g/g. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.21 wt%, the nitrogen content was 2016. mu.g/g, the carbon residue value was 4.54 wt%, and the metal (Ni + V) content was 7.37. mu.g/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 hydrogenation treatment process (at the moment, the raw material oil A sequentially flows through the mixer 5, the reactor 2, 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 downstream RFCC. When the content of metal (Ni + V) of the effluent at the outlet of the reactor 2 of the second hydrogenation pretreatment reaction zone exceeds 12 mu g/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 of the first hydrogenation pretreatment reaction zone 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 fresh catalyst is filled again for standby. By circulating in this way, the residual oil hydrogenation device is finally operated for 24 months, shutdown is carried out due to the deterioration of product quality, and the reactor 1 and the reactor 2 are respectively loaded and unloaded 2 times during the operation.
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 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 lower than that of the hydrogenation treatment zone, the specific reaction conditions and the residue hydrogenation reaction result are shown in table 3, the catalytic cracking operation conditions are shown in table 5, and the distribution of catalytic cracking products and the properties of catalytic cracking gasoline are shown in table 6. Raw oil A sequentially flows through a mixer 5, a reactor 1, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, one part of reaction effluent is circulated to the mixer 5 (the circulation ratio is 0.3: 1), the other part of reaction effluent enters a catalytic cracking reaction zone after gas-liquid separation and fractionation, all catalytic cracking slurry oil and 40 percent of all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to the mixer 5, 40 percent of all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to a hydrotreating reaction zone hydrogen mixing tank 6, catalytic cracking diesel oil is directly discharged out of the device, and the content of metal (Ni + V) in effluent at the outlet of the hydrotreating reaction zone is not controlled. The effluent of the hydrotreating reaction zone after hydrogenation had a sulfur content of 0.22 wt.%, a nitrogen content of 2164 μ g/g, a carbon residue value of 4.74 wt.% and a metal (Ni + V) content of 9.55 μ g/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 mixer 5, the reactor 2, 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 residuum hydrotreater unit was operated for another 7.5 months, with shutdown occurring due to product quality degradation, and finally the unit was operated for 17.5 months.
Example 2
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 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, the specific reaction conditions and the residual oil hydrogenation reaction result are shown in table 4, the catalytic cracking operation conditions are shown in table 5, and the catalytic cracking product distribution and the catalytic cracking gasoline property are shown in table 6. Raw oil B sequentially flows through a mixer 5, a reactor 1, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, one part of reaction effluent is circulated to the mixer 5 (the circulation ratio is 0.4: 1), the other part of reaction effluent enters a catalytic cracking reaction zone after gas-liquid separation and fractionation, all catalytic cracking slurry oil and 25% of all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to the mixer 5, 25% of all catalytic cracking recycle oil in the catalytic cracking reaction zone is circulated to a hydrotreating reaction zone hydrogen mixing tank 6, catalytic cracking diesel oil is directly discharged out of the device, and the content of metal (Ni + V) in the effluent at the outlet of the hydrotreating pretreatment reaction zone is controlled to be not higher than 20 mu g/g. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.23 wt%, the nitrogen content was 1556 μ g/g, the carbon residue value was 3.90 wt%, and the metal (Ni + V) content was 9.82 μ g/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 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 hydrogenation treatment process (at the moment, the raw material oil B sequentially flows through the mixer 5, the reactor 2, 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 downstream RFCC. When the content of metal (Ni + V) of the effluent at the outlet of the reactor 2 of the second hydrogenation pretreatment reaction zone exceeds 20 mu g/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 of the first hydrogenation pretreatment reaction zone 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 fresh catalyst is filled again for standby. By circulating in this way, the residual oil hydrogenation device is finally operated for 12 months, shutdown is carried out due to the deterioration of product quality, and the reactor 1 and the reactor 2 are respectively loaded and unloaded 2 times during the operation.
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 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 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, the specific reaction conditions and the residual oil hydrogenation reaction result are shown in table 4, the catalytic cracking operation conditions are shown in table 5, and the catalytic cracking product distribution and the catalytic cracking gasoline property are shown in table 6. Raw oil C sequentially flows through a mixer 5, a reactor 1, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, one part of reaction effluent is circulated to the mixer 5 (the circulation ratio is 0.5: 1), the other part of reaction effluent enters a catalytic cracking reaction zone after gas-liquid separation and fractionation, 80% of all catalytic cracking slurry oil in the catalytic cracking reaction zone and 20% of all catalytic cracking recycle oil are circulated to the mixer 5, 20% of all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to the hydrogen mixing tank 6 in a hydrotreating reaction zone, the catalytic cracking diesel oil is directly discharged out of the device, and the content of metal (Ni + V + Fe + Ca) in the effluent at the outlet of the hydrotreating reaction zone is controlled to be not higher than 10 mu g/g. The effluent of the hydrotreating reaction zone after hydrogenation had a sulfur content of 0.18 wt.%, a nitrogen content of 2615. mu.g/g, a carbon residue value of 3.62 wt.%, a metal (Ni + V) content of 5.67. mu.g/g, a metal Ca content of 0.68. mu.g/g, and a metal Fe content of 0.30. mu.g/g. After the operation is carried out for 4 months, the content of metal (Ni + V + Fe + Ca) of the effluent at the outlet of the reactor 1 in the first hydrogenation pretreatment reaction zone exceeds 10 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 hydrogenation treatment process (at the moment, the raw material oil B sequentially flows through the mixer 5, the reactor 2, 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 downstream RFCC. When the content of metal (Ni + V + Fe + Ca) of the effluent at the outlet of the reactor 2 of the second hydrogenation pretreatment reaction zone exceeds 10mg/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 of the first hydrogenation pretreatment reaction zone to continuously complete the hydrogenation treatment process, meanwhile, the catalyst in the reactor 2 of the second hydrogenation pretreatment reaction zone is replaced, and a fresh catalyst is filled again for standby. By circulating in this way, the residual oil hydrogenation unit is finally operated for 16 months, shutdown is carried out due to the deterioration of product quality, and the reactor 1 and the reactor 2 are respectively loaded and unloaded 2 times during the operation.
Example 4
According to the process flow illustrated in fig. 2, 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 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 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, the specific reaction conditions and the residual oil hydrogenation reaction result are shown in table 4, the catalytic cracking operation conditions are shown in table 5, and the catalytic cracking product distribution and the catalytic cracking gasoline property are shown in table 6. Raw oil A sequentially flows through a mixer 5, a reactor 1, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, one part of reaction effluent is circulated to the mixer 5 (the circulation ratio is 0.3: 1), the other part of reaction effluent enters a catalytic cracking reaction zone after gas-liquid separation and fractionation, 40% of all catalytic cracking oil slurry and all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to the mixer 5, 40% of all catalytic cracking recycle oil in the catalytic cracking reaction zone is circulated to the hydrogen mixing tank 6 in a hydrotreating reaction zone, 40% of all catalytic cracking diesel oil in the catalytic cracking reaction zone is circulated to the hydrogen mixing tank 7 in the hydrotreating reaction zone, and the content of metal (Ni + V) in the effluent at the outlet of the hydrotreating reaction zone is controlled to be not higher than 12 mug/g. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.21 wt%, the nitrogen content was 2011 μ g/g, the carbon residue value was 4.52 wt%, and the metal (Ni + V) content was 7.19 μ g/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 hydrogenation treatment process (at the moment, the raw material oil A sequentially flows through the mixer 5, the reactor 2, 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 downstream RFCC. When the content of metal (Ni + V) of the effluent at the outlet of the reactor 2 of the second hydrogenation pretreatment reaction zone exceeds 12 mu g/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 of the first hydrogenation pretreatment reaction zone 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 fresh catalyst is filled again for standby. By circulating in this way, the residual oil hydrogenation device is finally operated for 24 months, shutdown is carried out due to the deterioration of product quality, and the reactor 1 and the reactor 2 are respectively loaded and unloaded 2 times during the operation.
Example 5
According to the process flow illustrated in fig. 2, 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 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 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 2: 8.
In the operation process, the reaction temperature of the hydrogenation pretreatment reaction zone is higher than that of the hydrogenation treatment zone, the specific reaction conditions and the residual oil hydrogenation reaction result are shown in table 4, the catalytic cracking operation conditions are shown in table 5, and the catalytic cracking product distribution and the catalytic cracking gasoline property are shown in table 6. Raw material oil C sequentially flows through a mixer 5, a reactor 1, a hydrogen mixing tank 6, a reactor 3, a hydrogen mixing tank 7 and a reactor 4, one part of reaction effluent is circulated to the mixer 5 (the circulation ratio is 0.5: 1), the other part of reaction effluent enters a catalytic cracking reaction zone after gas-liquid separation and fractionation, 80 percent of all catalytic cracking slurry oil in the catalytic cracking reaction zone and 20 percent of all catalytic cracking recycle oil are circulated to the mixer 5, 20 percent of all catalytic cracking recycle oil in the catalytic cracking reaction zone are circulated to the hydrogen mixing tank 6 in a hydrotreating reaction zone, 20 percent of all catalytic cracking diesel oil (LCO) in the catalytic cracking reaction zone are cut into LCO light fraction and LCO heavy fraction, the cutting point is 275 ℃, the LCO heavy fraction is circulated to the hydrogen mixing tank 7 in the hydrotreating reaction zone, the LCO light fraction is circulated to the middle part of the reactor 4 in the hydrotreating reaction zone, and controlling the content of the metal (Ni + V + Fe + Ca) in the effluent at the outlet of the hydrogenation pretreatment reaction zone not to be higher than 10 mu g/g. The sulfur content in the effluent of the hydrotreating reaction zone after hydrogenation was 0.17 wt%, the nitrogen content was 2605. mu.g/g, the carbon residue value was 3.58 wt%, the metal (Ni + V) content was 5.40. mu.g/g, the metal Ca content was 0.65. mu.g/g, and the metal Fe content was 0.30. mu.g/g. After the operation is carried out for 4 months, the content of metal (Ni + V + Fe + Ca) of the effluent at the outlet of the reactor 1 in the first hydrogenation pretreatment reaction zone exceeds 10 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 hydrogenation treatment process (at the moment, the raw material oil B sequentially flows through the mixer 5, the reactor 2, 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 downstream RFCC. When the content of metal (Ni + V + Fe + Ca) of the effluent at the outlet of the reactor 2 of the second hydrogenation pretreatment reaction zone exceeds 10mg/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 of the first hydrogenation pretreatment reaction zone to continuously complete the hydrogenation treatment process, meanwhile, the catalyst in the reactor 2 of the second hydrogenation pretreatment reaction zone is replaced, and a fresh catalyst is filled again for standby. By circulating in this way, the residual oil hydrogenation unit is finally operated for 16 months, shutdown is carried out due to the deterioration of product quality, and the reactor 1 and the reactor 2 are respectively loaded and unloaded 2 times during the operation.
TABLE 3 hydrotreating conditions and results
TABLE 4 hydrotreating conditions and results
TABLE 5 catalytic cracking operating conditions
TABLE 6 catalytically cracked product distribution and catalytically cracked gasoline properties
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 and comparative example 1, respectively, and the results are shown in tables 7 and 8.
Wherein, the analysis method for analyzing the catalyst sample comprises the following steps:c content determination is carried out by adopting an EMZA-820V element analyzer produced in Japan; metal deposition measurements were performed using an IRIS HR plasma emission Spectroscopy (ICP) instrument from Thermo Fisher, USA; analysis of pore structure properties of catalyst by low temperature N2The adsorption method is carried out by an ASAP2420 type full-automatic physical adsorption apparatus (the analysis method is GB/T-19587).
TABLE 7 catalyst C analysis results before and after operation
TABLE 8 catalyst D analysis results
From the above analysis, it can be seen that by changing the catalyst system and operation mode of the residual oil hydrogenation apparatus, i.e. changing the prior art to show the trend of low front and high back according to the reaction temperature in the material flow direction (comparative example 1) and the trend of high front and low back according to the reaction temperature in the material flow direction (example 1), 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 carbon deposition inactivation by the prior art technology to only carbon deposition inactivation, 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 period, the catalyst is repeatedly used, the purchasing cost of the catalyst is saved, and the economical efficiency is improved.