CN218262386U - Composite bed hydrotreating system composed of fluidized bed and fixed bed - Google Patents

Abstract

The utility model discloses a composite bed hydrotreating system that ebullated bed-fixed bed is constituteed, composite bed hydrotreating system is including ebullated bed reaction unit, the stabilizing unit, fixed bed reaction unit, the separating unit who communicates in proper order, the separating unit includes gas-liquid separation unit and fractionation unit, and it is used for receiving the reaction effluent who comes from fixed bed reaction unit, obtains the purpose product after the separation. The composite bed hydrotreating system solves the problem that the pressure drop of a subsequent fixed bed reactor is easy to rise due to the fact that solid impurities are carried by materials at the outlet of the fluidized bed reactor, further solves the problem that the operation stability of a subsequent fixed bed reaction zone is poor due to the occurrence of bed hot spots, and greatly improves the operation stability of the fixed bed reaction zone.

Description

Composite bed hydrotreating system composed of fluidized bed and fixed bed

Technical Field

The utility model belongs to oil refining chemical industry field relates to a combination hydrotreating system, especially relates to a composite bed hydrotreating system that ebullated bed-fixed bed is constituteed.

Background

The fixed bed residual oil hydrogenation technology is used as a main means for processing heavy oil at present, and has wide market share at home and abroad due to mature technology and simple operation. With the increasingly intensified trend of raw material deterioration and heaviness and the increasingly strict environmental protection requirement, the shortage of the fixed bed residual oil hydrogenation technology is increasingly prominent, and when processing the poor raw material with high viscosity, high carbon residue and high metal content, the traditional fixed bed residual oil hydrogenation technology has the problems of relatively poor raw material adaptability, high reactor bed pressure drop, short operation period and the like, and usually the total metal content of the fixed bed raw oil is required to be controlled to be less than 150 mug/g, the carbon residue to be less than 15wt%, and the asphaltene content to be less than 5wt%. On the other hand, when the inferior raw material is treated, the fixed bed catalyst is coked and deactivated quickly; in the final stage of operation, bed layer material flow distribution is uneven, problems of bed layer hot spots, radial temperature difference and the like can be caused, and finally the operation period of the fixed bed device is shortened. Short run length has become a major factor limiting the development of fixed bed residuum hydrogenation technology. Frequent shutdown and replacement of the catalyst cause serious troubles to normal production of enterprises, in addition, the increase of catalyst consumption and production fluctuation caused by the frequent shutdown and replacement of the catalyst cause serious influence to the balance of the whole enterprise, and especially under the aim of double carbon, the maximum extension of the operation period of a fixed bed residual oil hydrogenation device becomes an important subject in the field of heavy oil hydrogenation at present. Researchers at home and abroad are going on a great deal of research work from the aspects of new process development, catalyst preparation, grading system research and development and the like around prolonging the operation period of the device, wherein a typical UFR protection reactor technology developed by CLG is adopted, the catalyst in the UFR protection reactor is in a micro-expansion state, but the problems of radial temperature difference and the like in the final operation stage cannot be solved.

The fluidized bed hydrogenation technology is an important means for processing inferior raw materials, the fluidized bed reactor is adopted, the inside of the reactor is in an approximate full back-mixing state, the temperature distribution is uniform, the mass transfer and the heat transfer among materials in the reactor are facilitated to be better, the depolymerization of asphaltene macromolecules in residual oil raw materials can be well realized by matching with the effective regulation and control of key physical parameters such as the aperture, the pore volume and the like of a fluidized bed catalyst, the metals such as Ni, V and the like in the residual oil raw materials can be efficiently removed, the two problems of asphaltene conversion and metal removal in the traditional residual oil hydrogenation technology are solved, and meanwhile, the fluidized bed reactor is helpful for solving the problems of bed pressure drop, hot spots and the like. The boiling bed is used as a protective reactor of the traditional fixed bed reactor, which is beneficial to improving the adaptability of raw materials and solving the problems of short running period and the like of the fixed bed reactor, and how to realize the connection of the two types of reactors is a problem to be solved urgently.

Patent CN102041084A discloses a heavy hydrocarbon hydrogenation combined process method, which comprises mixing a heavy hydrocarbon raw material and a gas phase from a fixed bed hydrogenation reaction effluent, feeding the mixture into a boiling bed hydrogenation reactor, removing hydrogen sulfide from the gas phase generated by hydrogenation reaction, feeding the gas phase and the boiling bed liquid phase into a fixed bed hydrogenation reaction, directly using the fixed bed hydrogenation reaction gas phase in the boiling bed reaction process, and fractionating the liquid phase of the fixed bed hydrogenation reaction effluent to obtain gasoline and diesel oil and unconverted oil. In the patent technology, in order to strengthen the reaction effect in the fluidized bed reactor, the gas phase generated by the hydrogenation reaction of the fixed bed reactor is directly used in the reaction process of the fluidized bed reactor, so that the volume ratio of hydrogen to oil in the fluidized bed reactor is far higher than the normal value, the fluidized bed reactor is used as the fluidized bed reactor, and the ultrahigh volume ratio of hydrogen to oil can easily cause the loss of materials such as a catalyst and the like, thereby causing the blockage of the bed layer of the subsequent fixed bed reactor; secondly, in the patent technology, the boiling bed reaction unit adopts a conventional high-temperature operation mode, so that the instability of an asphaltene system is easily caused, the problems of coking and the like appear in a subsequent fixed bed reaction bed layer, and the operation safety and long-period stable operation of the device are seriously influenced.

SUMMERY OF THE UTILITY MODEL

During research and industrial experiments on the treatment of heavy oil raw materials by using a boiling-solid composite bed, the fixed bed reactor in the composite bed still has abnormal problems of rapid pressure drop increase, bed hot spots and the like compared with the single fixed bed treatment, and the result is contrary to the cognition of the technical personnel in the field on the hydrogenation reaction rule of the hydrocarbon-containing materials and is not in line with the expected result of the technical personnel in the field. A large amount of exploration and analysis are carried out from the aspects of raw material composition analysis, process route adjustment, process condition regulation and the like, and the preliminarily obtained conclusion indicates that the fluidized bed reactor in the composite bed route has strong raw material adaptability as a protective reactor and can solve the problems of pressure drop, hot spots and the like of the traditional fixed bed protective reactor, but as the fluidized bed reactor is used as a fluidized bed reactor, the phenomenon of short circuit of raw material oil exists, so that a certain amount of solid impurities and particles exist in the material at the outlet of the fluidized bed reactor, which is the reason for causing the pressure drop rise of the subsequent fixed bed reactor; in addition, the fluctuation of the liquid phase feed at the inlet of the fixed bed reactor is another cause of the generation of bed hot spots in the fixed bed reactor and the difficulty in stable operation of the apparatus. After further intensive research on the phenomenon, it is found that, in the boiling-solid composite bed hydrotreating process, especially when an ebullated bed reactor with a built-in three-phase separator is adopted, the liquid phase outlet of the ebullated bed reactor appears as a stable liquid phase stream in principle, and the liquid phase stream can be directly sent to a subsequent processing unit for processing as long as the feed of the ebullated bed reactor is stable, and the liquid phase material discharged in principle is also stable according to the conventional practice in the art after separation by the three-phase separator inside the ebullated bed reactor. However, after intensive research, the liquid phase stream discharged from the liquid phase outlet belongs to a gas-liquid mixed phase stream, and a certain amount of solid impurities exist in the material at the outlet of the boiling bed, and particularly, the stabilization is more difficult on a composite bed industrial device with a direct combination of the boiling bed and the fixed bed. Because the liquid phase discharged outside the fluidized bed is in an overflow discharge mode on the liquid level surface, a liquid level control system is not arranged in the fluidized bed reactor, and the liquid level is difficult to fluctuate during operation under the influence of pressure and the like, the feed flow is difficult to ensure to be pure liquid phase, the microcosmic substance is gas-liquid mixed phase flow, and the situation that no liquid phase is discharged in a short time or the liquid phase discharge amount is obviously higher than the normal amount sometimes occurs. Moreover, due to the compressibility of gas and the self reaction working condition of the fluidized bed reactor and the fluctuation of the liquid level of the fluidized bed reactor, the amount of liquid-phase materials entering a subsequent fixed bed reactor is unstable, sometimes even the situation of short-time material breaking occurs, and the fixed bed reactor is easy to deviate from the normal working condition frequently in production, so that the problems of device fluctuation, bed hot spots and the like are caused; in addition, as mentioned above, the fluidized bed is a fluidized bed reactor, and the situation that the solid impurities in the inferior raw material enter the subsequent reactor through a short circuit cannot be completely avoided, in the boiling-solid composite bed hydrotreatment system, because: the communication between the two systems, particularly the communication between the hydrogen system, is more obvious, for example, the pressure change of the fixed bed system can also be affected to the boiling bed reaction system; (II) because of the requirements of reaction, temperature control and the like, the quantity of circulating hydrogen required by a fixed bed reaction system is larger, and the instability of liquid-phase materials discharged out of a boiling bed is aggravated when a large quantity of gas phases are mixed with gas-liquid mixed-phase materials discharged out of the boiling bed in material flow; and thirdly, when the boiling bed is used for processing the inferior raw material, solid impurities and catalyst powder carried in the raw material can enter a bed layer of a subsequent fixed bed reactor, so that the pressure drop of the fixed bed reactor is abnormally increased. Therefore, stability and pressure drop control of a boiling-solid composite bed hydroprocessing system become one of the important issues for industrial implementation. The present application proposes a solution based on the above-mentioned research and findings. During technical development and industrial application, some phenomena are found which are not completely consistent with the general knowledge of the skilled person. Generally, when the raw material obtained by pretreating inferior and heavy raw materials by using a fluidized bed is subjected to deep hydrotreatment in a fixed bed, the operation of the fixed bed reactor is more stable, and the problems that hot spots frequently occur in the first reactor of the fixed bed when the inferior raw materials are directly treated and then the bed pressure drop is increased quickly and the stability is insufficient are not caused. However, in the research, the practical results are not consistent with the above knowledge, and after the gas phase and liquid phase materials after the ebullated bed reaction are directly introduced into the fixed bed reaction unit, the problems of hot spots and pressure drop of the first reactor in the fixed bed reaction unit are weakened but not completely eliminated, and the expected target is not achieved. Aiming at the problems that hot spots frequently occur in a fixed bed reactor in the research process of a composite bed hydrogenation process consisting of a fluidized bed and a fixed bed, the pressure drop is increased, the operation stability is poor, the operation cycle of the fixed bed is not matched with that of the fluidized bed, so that the long-cycle stable operation of the whole device is influenced, and the like, the novel fluidized bed-fixed bed composite bed hydrogenation process with the stabilizing unit and the material circulating unit arranged between the fluidized bed reaction unit and the fixed bed reaction unit is provided, the process route solves the problem that the pressure drop of a subsequent fixed bed reactor is increased easily due to the fact that a material at the outlet of the fluidized bed reactor carries solid impurities, further solves the problem that the operation stability of the subsequent fixed bed reaction unit is poor due to the occurrence of bed hot spots, and greatly improves the operation stability of the fixed bed reaction unit; on the other hand, the problem that the operation periods of the fixed bed reaction unit and the fluidized bed reaction unit are not matched is solved, the operation period of the whole set of hydrogenation device is greatly prolonged, the shutdown times in the overhaul period are reduced, and the upgrading and updating of the hydrogenation technology are realized.

The utility model mainly aims at providing a composite bed hydrotreating system composed of a fluidized bed and a fixed bed, which comprises a fluidized bed reaction unit, a stabilizing unit, a fixed bed reaction unit and a separating unit which are communicated in sequence;

the fluidized bed reaction unit is provided with more than one fluidized bed reactor, is used for receiving raw oil and hydrogen, contacts with a fluidized bed hydrogenation catalyst to react, and obtains a first gas-phase material and a second gas-phase material after the obtained reaction materials are separated by a three-phase separator in the fluidized bed reactor;

the stabilizing unit comprises more than one stabilizing tank, and the stabilizing tank is provided with at least one feeding hole and two discharging holes; the two discharge ports are respectively marked as a first discharge port and a second discharge port; the feed inlet is used for receiving a second material from the fluidized bed reaction unit, the first discharge outlet is used for discharging a 21 st material flow, and the second discharge outlet is used for discharging a 22 nd material flow;

the fixed bed reaction unit is provided with at least one fixed bed reactor and is used for receiving the 21 st material flow and the 22 nd material flow from the stabilizing unit, reacting under the action of hydrogen and a fixed bed hydrogenation catalyst, and obtaining a reaction effluent after reaction;

and the separation unit comprises a gas-liquid separation unit and a fractionation unit, and is used for receiving the reaction effluent from the fixed bed reaction unit and obtaining a target product after separation.

Preferably, in the above composite bed hydroprocessing system composed of the ebullated bed and the fixed bed, the ebullated bed reactor is a ebullated bed reactor in which a three-phase separator is arranged inside the reactor, the ebullated bed reactor with the three-phase separator can realize primary separation of three phases of gas phase, liquid phase and solid phase in the reacted material through the three-phase separator inside the reactor, the gas phase is generally treated after being discharged through a gas phase outlet at the top of the reactor, the liquid phase is generally treated after being discharged through a liquid phase outlet arranged on the side wall of the reactor, and the solid phase (mainly, ebullated bed hydroprocessing catalyst) obtained after separation is recycled inside the ebullated bed reactor. The fluidized bed reactor can adopt a fluidized bed reactor with a built-in three-phase separator developed by China petrochemical company Limited (Dalian) compliant petrochemical research institute, and specifically can be one or more of patent publication structures of ZL 200710012680.9, ZL200810012191.8 and the like.

Further preferably, in the composite bed hydrotreatment system consisting of the ebullated bed and the fixed bed, the stabilization tank can be a vertical tank and/or a horizontal tank, and is preferably a horizontal tank; the lower part of the further optimized stabilization tank adopts a conical design; further preferably, a baffle plate inner component is arranged inside the stabilizing tank and used for intercepting the scales and preventing the scales from being brought into a subsequent fixed bed reactor.

Further preferably, in the composite bed hydrotreatment system consisting of the fluidized bed and the fixed bed, the stabilization tank is provided with a feed inlet and two discharge outlets; the two discharge ports are respectively marked as a first discharge port and a second discharge port; wherein the feed inlet is used for receiving a second material from the ebullated-bed reaction unit; the first outlet is used for discharging a 21 st material flow, and the second outlet is used for discharging a 22 nd material flow. Furthermore, the feed inlet is arranged on the tank body of the stabilization tank, the first discharge outlet is arranged at the top of the stabilization tank or at the upper part of the other side of the stabilization tank relative to the direction of the feed inlet, the second discharge outlet is arranged at the middle lower part of the other side of the stabilization tank relative to the direction of the feed inlet, and when the first discharge outlet is arranged at the upper part of the stabilization tank, the height difference between the first discharge outlet and the second discharge outlet is 60-90% of the height of the tank body of the stabilization tank; the relative height difference between the feed inlet and the second discharge outlet is 40-70% of the height of the tank body of the stabilizing tank, preferably 50-65%, and the arrangement is carried out so as to ensure the separation stabilizing effect of the liquid phase 2 nd material flow in the stabilizing tank.

Further preferably, in the composite bed hydrotreatment system consisting of the fluidized bed and the fixed bed, the stabilization tank is provided with one feeding port and three discharging ports; the three discharge ports are respectively marked as a first discharge port, a second discharge port and a third discharge port; wherein the feed inlet is used for receiving a second material from the ebullated bed reaction unit; the first discharge port is used for discharging a 21 st material flow, and the second discharge port is used for discharging a 22 nd material flow; the third outlet port is used to discharge a 23 rd stream. Furthermore, the feed inlet is arranged on the tank body of the stabilization tank, the first discharge outlet is arranged at the top of the stabilization tank or at the upper part of the other side of the stabilization tank relative to the direction of the feed inlet, the second discharge outlet is arranged at the middle lower part of the other side of the stabilization tank relative to the direction of the feed inlet, the third discharge outlet is arranged at the bottom of the stabilization tank or at the lower part of the other side of the stabilization tank relative to the direction of the feed inlet, and when the first discharge outlet is arranged at the upper part of the stabilization tank, the height difference between the first discharge outlet and the second discharge outlet is 60% -90% of the height of the tank body of the stabilization tank; the relative height difference between the feed inlet and the second discharge port is 40-70% of the height of the tank body of the stabilization tank, preferably 50-65%, and the relative height difference between the feed inlet and the third discharge port is 75-95% of the height of the tank body of the stabilization tank, preferably 80-90%.

Preferably, a circulating pump is arranged in the composite bed hydrotreating system consisting of the fluidized bed and the fixed bed, and the 23 rd material flow obtained by separation of the stabilizing unit is led to a lower end socket of the fluidized bed reactor through the circulating pump; the design flow of the circulating pump is 20-70%, preferably 30-50% of the rated flow of the fresh raw material, the 23 rd material flow separated by the stabilizing unit is led to the lower end enclosure of the fluidized bed reactor through the circulating pump to be treated, on one hand, the solid impurities obtained by solid-liquid sedimentation separation in the stabilizing tank are discharged to the lower end enclosure of the fluidized bed reactor through the circulating pump, and then the solid impurities are timely discharged by virtue of the online adding and discharging system of the catalyst of the fluidized bed reactor, so that the deposition and coking of the solid impurities in the system are avoided; and on the other hand, the arrangement of the circulating pump can ensure the stable operation in the reactor under the condition of low-load feeding of the fluidized bed.

Preferably, in the above composite bed hydrotreating system composed of the fluidized bed and the fixed bed, the stabilization tank is provided with a liquid level control system, specifically, a control valve may be arranged on a second discharge port pipeline of the stabilization tank, and the opening of the control valve on the second discharge port pipeline is correspondingly adjusted according to the liquid level in the stabilization tank; the third discharge gate links to each other with the circulating pump entry, need not to set up the control valve, adjusts pump outlet flow through the rotational speed of control circulating pump, and then the liquid level in the adjustment stabilization tank.

Further preferably, in the above-mentioned combined bed hydrotreating system composed of the ebullated bed and the fixed bed, the fixed bed reaction unit is provided with at least 1 fixed bed reactor, preferably a plurality of fixed bed reactors are provided in series, and more preferably 3 to 5 fixed bed reactors are provided. Taking the fixed bed heavy oil hydrotreating technology which is industrially mature at present as an example, the adopted fixed bed hydrotreating catalyst generally refers to a single catalyst or a combined catalyst with functions of hydrodemetallization, hydrodesulfurization, hydrodenitrogenation and the like.

Further preferably, in the above composite bed hydroprocessing system comprising ebullated bed and fixed bed, the separation unit comprises a gas-liquid separation unit and a fractionation unit, and the gas-liquid separation unit generally comprises a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator and a cold low-pressure separator; the fractionation unit includes a fractionation column. The separation comprises two steps of gas-liquid separation and fractionation, wherein the gas-liquid separation is generally realized in a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator and a cold low-pressure separator; the fractionation is generally carried out in a fractionating tower, the target products can be gasoline, diesel oil and hydrogenated heavy oil, and the hydrogenated heavy oil can be used as a raw material for catalytic cracking

Further preferably, the composite bed hydrotreating system composed of the ebullated bed and the fixed bed further comprises a recycle hydrogen desulfurization tower, which is used for receiving and treating a gas phase obtained from the separation in the separation unit by the hot high-pressure separator, and the gas phase obtained after treatment is used as recycle hydrogen to be introduced into the fixed bed reaction unit and/or the ebullated bed reaction unit after being subjected to pressure boosting.

Preferably, in the above composite bed hydrotreating system composed of a fluidized bed and a fixed bed, the gas phase (mainly light hydrocarbons corresponding to naphtha and light diesel oil) separated by the stabilization tank and the liquid phase separated by the stabilization tank are mixed and then used as the fixed bed reaction unit for feeding, on one hand, the gas phase and the liquid phase are mixed at the inlet of the fixed bed reactor instead of being mixed in the front end pipeline, which helps to avoid the fixed bed feeding fluctuation caused by compressibility of the gas phase, helps to improve the feeding stability of the fixed bed reactor, and improves the operation stability of the device; on the other hand, the method is favorable for reducing the feeding viscosity of the fixed bed treatment area and improving the diffusion speed of reaction raw materials, particularly the diffusion speed in catalyst pore channels, thereby improving the hydrogenation reaction effect of the fixed bed.

Further preferably, in the above composite bed hydrotreating system composed of the ebullated bed and the fixed bed, the first gas-phase material obtained in the ebullated bed reaction unit enters the fixed bed reaction unit through a pipeline, and contacts with the feed to react under the action of the fixed bed hydrotreating catalyst.

Further preferably, in the above composite bed hydroprocessing system composed of ebullated bed and fixed bed, the ebullated bed reactor may be optionally provided with or without a high-pressure on-line catalyst charging and discharging system according to actual requirements. Further, when a high-pressure online catalyst charging and discharging system is arranged, the boiling bed reactor adopts temperature-changing operation, the activity of the catalyst is high in the initial operation stage (generally not more than 20% of the whole operation period, and generally 5% -15% of the whole operation period), the operation is carried out at the reactor temperature which is 10-15 ℃ lower than the normal operation temperature, and the charging and discharging operation of the catalyst is not needed in the stage; when the operation is carried out to the middle stage, the operation is carried out according to the normal operation temperature, and simultaneously the catalyst emission adding operation is started; at the end of the operation (generally not more than 15% of the whole operation period, usually 5-10% of the whole operation period), stopping the on-line feeding and discharging of the catalyst, and adopting the operation of raising the temperature (15-20 ℃ higher than the normal operation temperature) to fully exert the activity of the catalyst. The consumption of the catalyst in the whole operation process is reduced to the maximum extent. When a high-pressure online catalyst adding and discharging system is not arranged, the activity loss of the catalyst can be compensated by adjusting the reaction temperature (generally, the reaction temperature is increased at the end stage) according to the activity change of the catalyst in the running process, so that the stability of the product property is ensured.

Compared with the prior art, the composite bed hydrotreating system composed of the fluidized bed and the fixed bed has the following technical advantages.

Unlike the above-described conventional ebullated-bed hydrotreating process for high conversion, the ebullated-bed reactor in the treatment process using the ebullated-bed hydrotreating system of the present application, which is a combined-bed hydrotreating system composed of ebullated-fixed beds and is mainly aimed at the demetallization pretreatment of feedstock and the asphaltene conversion, is generally controlled to be not higher than 40%, preferably not higher than 25%, and more preferably not higher than 15%. At such low conversion operating conditions, the proportion of hydrocarbon-containing feedstock undergoing cracking reactions is also relatively low, and gas phase product yields are typically no greater than 2.0%. In addition, in combination with the ebullated-bed reactor with the built-in three-phase separator, which is used in the present application, when the above situations are faced, the gas phase is generally considered to be discharged through the gas phase outlet at the top of the ebullated-bed reactor, and because the ebullated-bed reactor mainly performs hydrodemetallization reaction, index contents of sulfur, nitrogen and the like in the obtained liquid phase material flow still do not meet requirements, and the subsequent hydrotreating needs to be performed on the whole liquid phase fraction, so when the above situations are faced, technicians have no motivation to separate the liquid phase material flow discharged from the liquid phase outlet again, and the general idea is to directly perform the subsequent hydrotreating on the whole liquid phase material flow, and then separate the hydrogenated product according to needs.

The utility model provides an among the composite bed hydrotreating system that ebullated bed-fixed bed is constituteed, be different from the theory that ebullated bed reactor adopted high conversion rate in the traditional technical route, ebullated bed adopts low conversion rate operation in this technical route, can reduce ebullated bed hydrogenation reaction product by a wide margin and because of system unstability, the asphaltene coking scheduling problem that the conversion rate is high causes at follow-up fixed bed reactor, help avoiding fixed bed reactor pressure drop to rise fast and improve the operating stability of device.

In the composite bed hydrotreatment system consisting of the fluidized bed and the fixed bed, the thermal coupling mode of the fluidized bed and the fixed bed reactor is adopted, the manual cooling link is not needed, the reaction heat of the fluidized bed is fully utilized, the fuel consumption is saved, and the energy consumption is reduced; meanwhile, the heat combination process flow simplifies the flow and reduces the complexity of the device.

In the composite bed hydrotreating system composed of the fluidized bed and the fixed bed, based on the characteristic that the fluidized bed reactor adopting the built-in three-phase separator and the microspherical fluidized bed hydrogenation catalyst are easy to fluidize, and the condition of low conversion depth of a fluidized bed treatment area is controlled, the load of a recycle hydrogen compressor can be reduced to the maximum extent and the equipment investment is reduced by adjusting the recycle hydrogen distribution and the consumption of the fluidized bed reactor and the fixed bed reactor; the boiling bed treatment zone can meet the requirements of reaction and fluidization only by maintaining a relatively low hydrogen-oil volume ratio; while the fixed bed treatment zone needs to maintain a higher hydrogen to oil volume ratio to ensure the reaction and heat carrying requirements in the fixed bed treatment zone. The regulation and control of the hydrogen-oil volume ratio of the boiling bed and the fixed bed in the composite bed process have great influence on the reaction result, if the hydrogen-oil volume ratio of the boiling bed reactor is larger, the retention time of a liquid phase in the reactor is shorter, and the reaction cannot achieve the expected effect; if the volume ratio of hydrogen to oil in the fixed bed reactor is smaller, the reaction requirement cannot be met or heat in a fixed bed treatment area cannot be effectively carried, so that abnormal working conditions such as bed layer temperature runaway and the like occur.

In the composite bed hydrotreatment system composed of the fluidized bed and the fixed bed, aiming at the objective problems that the fixed bed feeding fluctuation causes the device to generate hot spots and the operation stability is poor in the combined process technology of the fluidized bed and the fixed bed, the problem is solved by arranging the stabilizing unit between the fluidized bed reaction unit and the fixed bed reaction unit; the objective problem of abnormal rise of bed pressure drop of the fixed bed reactor is solved by arranging a circulating oil pump at the lower part of a stabilizing tank between a fluidized bed and a fixed bed reaction unit. The arrangement of the stabilization tank solves the problem of influence of gas-liquid phase-mixed flow on the feeding of the fixed bed reactor, and greatly improves the running stability of the device. The circulating pump can timely convey the solid impurities settled in the stabilization tank to the lower end socket of the fluidized bed reactor, and then timely discharge the solid impurities out of the system, so that the solid impurities are prevented from being carried into a subsequent fixed bed reactor.

The utility model provides an among the composite bed hydrotreating system that ebullated bed-fixed bed is constituteed, adopt ebullated bed reactor as the protection reactor, through distinctive reactor form and supporting high activity catalyst in with the feeding metal and asphaltene macromolecule most take off and get rid of, optimize follow-up fixed bed feeding property, show extension fixture operation cycle.

Drawings

FIG. 1 is a schematic view of a combined fluidized bed-fixed bed hydroprocessing system according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a combined fluidized bed-fixed bed hydroprocessing system according to a second embodiment of the present invention.

Fig. 3 is a schematic structural view of the fluidized bed reactor of the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention is provided, but it should be noted that the scope of the present invention is not limited by the embodiments, but is defined by the appended claims.

All publications, patent applications, patents, and other references mentioned in this specification are herein incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, including definitions, will control.

When the specification concludes with claims with the heading "known to those skilled in the art", "prior art", or the like, to derive materials, substances, methods, procedures, devices, or components, etc., it is intended that the subject matter derived from the heading encompass those conventionally used in the art at the time of filing this application, but also include those that are not currently in use, but would become known in the art to be suitable for a similar purpose.

In the context of this specification, any two or more embodiments of the invention may be combined in any combination, and the resulting solution is part of the original disclosure of this specification, and is within the scope of the invention.

The utility model discloses well ebullated bed reaction unit sets up a ebullated bed hydrogenation ware, ebullated bed reactor can adopt the structure in ZL200810012191.8, and fixed bed reaction unit sets up 4 fixed bed reactors.

As shown in fig. 1 and fig. 2, the composite bed hydrotreating system composed of a fluidized bed and a fixed bed provided by the present invention comprises a fluidized bed reaction unit, a stabilization unit, a fixed bed reaction unit, and a separation unit, which are sequentially communicated; the fluidized bed reaction unit is provided with more than one fluidized bed reactor 3, the fluidized bed reactor 3 is used for receiving raw oil 1 and hydrogen 2 and is contacted with a fluidized bed hydrogenation catalyst to react, the obtained reaction materials are separated by a three-phase separator in the fluidized bed reactor to obtain a first gas-phase material 4 and a second gas-phase material 6, the first gas-phase material 4 is discharged from an outlet at the top of the fluidized bed reactor, the second gas-phase material 6 is discharged from an overflow outlet on the side wall of a reactor cylinder body at the position, lower than the outlet of the first gas-phase material, of the upper part of the fluidized bed reactor and enters the stabilizing unit, the stabilizing unit comprises more than one stabilizing tank 5, and the stabilizing tank 5 is provided with at least one feeding hole and three discharging holes; the three discharge ports are respectively marked as a first discharge port, a second discharge port and a third discharge port; a feed inlet for receiving a second stream 6 from the ebullated bed reaction unit, a first discharge outlet for discharging a 21 st stream 7, a second discharge outlet for discharging a 22 nd stream 8, and a third discharge outlet for discharging a 23 rd stream 22; introducing the 23 rd material flow 22 into a lower head of the fluidized bed reactor for treatment through a circulating pump 21; the first gas phase material 4 separated by the boiling bed reactor, the 21 st material flow 7 separated by the stabilizing unit, and the 22 nd material flow 8 enter the fixed bed reaction unit as the feeding material of the fixed bed reaction unit, the fixed bed reaction unit is provided with more than 1 fixed bed reactor, for example, the first fixed bed reactor 9, the second fixed bed reactor 11, the third fixed bed reactor 13 and the fourth fixed bed hydrogenation reactor 15 can be specifically arranged, under the condition of hydrogen existence, the reaction material sequentially enters the first fixed bed reactor 9, the second fixed bed reactor 11, the third fixed bed reactor 13 and the fourth fixed bed hydrogenation reactor 15 for hydrodesulfurization, hydrodenitrogenation and hydrodecarbonization reaction, the specific process is that the reaction material firstly enters the first fixed bed reactor 9 for reaction, the reaction product 10 of the first fixed bed reactor obtained by the reaction enters the second fixed bed reactor 11 for reaction, the reaction product 12 of the second fixed bed reactor obtained by the reaction enters the third fixed bed reactor 13 for reaction, the reaction product 14 of the third fixed bed reactor obtained by the reaction enters the fourth fixed bed reactor 15 for reaction, the reaction product 16 of the fourth fixed bed reactor obtained by the reaction enters the gas-liquid separation unit 17 for gas-liquid separation, the separated gas 19 is cooled and desulfurized by a desulfurization tower (not shown in the figure) and then is used as circulating hydrogen 20, and the separated liquid phase 18 can enter a fractionating tower (not shown in the figure) for further separation according to product requirements, such as dry gas, liquefied gas, naphtha, diesel oil, hydrogenated heavy oil and the like can be obtained by fractionation.

As depicted in fig. 3, the ebullated-bed reactor comprises a reactor shell and a three-phase separator 11, wherein the reactor shell comprises an expanded section 4 and a straight-barrel section 3 from top to bottom in sequence, the three-phase separator 11 is arranged in the expanded section 4, the diameter of the expanded section 4 is 1.2 to 2 times of the diameter of the straight-barrel section, and the ratio of the diameter to the height of the expanded section is 0.3 to 2.0; the lower end of the enlarged section 4 may be an inverted open circular truncated cone, but may also be of other suitable geometric shapes. The angle of enlargement formed by the tangent at the intersection of the enlarged section and the straight section and the axis of the reactor is acute, preferably 45 to 60 degrees. The three-phase separator 11 is composed of an inner cylinder 5, an outer cylinder 6 and the shell inner wall of the reactor expansion section 4. The straight section of the inner cylinder 5 forms a central tube of the three-phase separator, the annular space between the inner cylinder 5 and the outer cylinder 6 forms a deflection cylinder of the three-phase separator, the annular space between the outer cylinder 6 and the inner wall of the shell of the expanded section 4 of the reactor is a clear liquid product collecting region, the opening of the diffusion section at the lower end of the central tube is a material flow introducing port, and the annular opening formed by the opening of the diffusion section and the inner wall of the shell of the expanded section 4 of the reactor is a catalyst feed port. The specific working process is as follows: the raw material enters a fluidized bed reactor from a feeding hole 1, passes through a gas-liquid distributor 2, uniformly passes through a catalyst bed layer 7, contacts with a catalyst to carry out hydrogenation reaction, and under the action of cocurrent and upward flow of gas-liquid phase materials, the catalyst bed layer can expand to a certain degree, and the volume of the expanded catalyst bed layer is usually 20-70% larger than the static volume of the expanded catalyst bed layer. The oil gas after hydrogenation reaction carries partial catalyst particles to enter a three-phase separator 11 through an expansion area 8 surrounded by an expansion section 4 for gas-liquid-solid three-phase separation: the gas is first separated and exits the reactor through a gas discharge 10, the separated catalyst is returned to the reaction zone through a feed opening 13, and a clarified stream, substantially free of catalyst particles, exits the reactor through a liquid discharge 12. In order to replenish fresh catalyst and to discharge deactivated catalyst out of the reactor in time, fresh catalyst may be replenished into the reaction system through the upper catalyst-introducing pipe 9 of the reactor, and part of the deactivated catalyst may be discharged out of the reaction system through the lower discharge pipe 14 of the reactor.

Claims (19)

1. A composite bed hydrotreating system that ebullated bed-fixed bed is constituteed which characterized in that: the composite bed hydrotreatment system comprises a fluidized bed reaction unit, a stabilization unit, a fixed bed reaction unit and a separation unit which are sequentially communicated;

the fluidized bed reaction unit is provided with more than one fluidized bed reactor and is used for receiving raw oil and hydrogen and contacting with a fluidized bed hydrogenation catalyst to react, the obtained reaction material is separated by a three-phase separator in the fluidized bed reactor to obtain a first gas-phase material and a second gas-phase material, the first gas-phase material is discharged through an outlet at the top of the fluidized bed reactor, and the second gas-phase material is discharged from an overflow outlet on the side wall of a reactor cylinder body, which is arranged at the upper part of the fluidized bed reactor and is lower than the outlet of the first gas-phase material;

the stabilizing unit comprises more than one stabilizing tank, and the stabilizing tank is provided with at least one feeding hole and two discharging holes; the two discharge ports are respectively marked as a first discharge port and a second discharge port; the feed inlet is used for receiving a second material from the fluidized bed reaction unit, the first discharge outlet is used for discharging a 21 st material flow, and the second discharge outlet is used for discharging a 22 nd material flow;

the fixed bed reaction unit is provided with at least one fixed bed reactor and is used for receiving the 21 st material flow and the 22 nd material flow from the stabilizing unit, reacting under the action of hydrogen and a fixed bed hydrogenation catalyst, and obtaining a reaction effluent after reaction;

and the separation unit comprises a gas-liquid separation unit and a fractionation unit, and is used for receiving the reaction effluent from the fixed bed reaction unit and separating to obtain a target product.

2. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the fluidized bed reactor adopts a fluidized bed reactor with a three-phase separator arranged in the reactor.

3. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the boiling bed reactor is provided with or not provided with a high-pressure on-line catalyst charging and discharging system.

4. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the stabilizing tank is a vertical tank and/or a horizontal tank.

5. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1 or 4, wherein: the stabilization tank is a horizontal tank.

6. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1 or 4, wherein: the lower part of the stabilization tank adopts a conical design.

7. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1 or 4, wherein: the stabilizing tank is internally provided with a baffle plate.

8. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the stabilizing tank is provided with a feed inlet and two discharge outlets; the two discharge ports are respectively marked as a first discharge port and a second discharge port; wherein the feed inlet is used for receiving a second material from the ebullated bed reaction unit; the first discharge port is used for discharging a 21 st material flow, and the second discharge port is used for discharging a 22 nd material flow; the feed inlet is arranged on a tank body of the stabilization tank, the first discharge outlet is arranged at the top of the stabilization tank or at the upper part of the other side of the stabilization tank relative to the direction of the feed inlet, the second discharge outlet is arranged at the middle lower part of the other side of the stabilization tank relative to the direction of the feed inlet, and when the first discharge outlet is arranged at the upper part of the stabilization tank, the height difference between the first discharge outlet and the second discharge outlet is 60-90% of the height of the tank body of the stabilization tank; the relative height difference between the feed inlet and the second discharge outlet is 40-70% of the height of the tank body of the stabilization tank.

9. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the stabilizing tank is provided with a feeding hole and two discharging holes; the two discharge ports are respectively marked as a first discharge port and a second discharge port; wherein the feed inlet is used for receiving a second material from the ebullated bed reaction unit; the first discharge port is used for discharging a 21 st material flow, and the second discharge port is used for discharging a 22 nd material flow; the feed inlet is arranged on a tank body of the stabilization tank, the first discharge outlet is arranged at the top of the stabilization tank or at the upper part of the other side of the stabilization tank relative to the direction of the feed inlet, the second discharge outlet is arranged at the middle lower part of the other side of the stabilization tank relative to the direction of the feed inlet, and when the first discharge outlet is arranged at the upper part of the stabilization tank, the height difference between the first discharge outlet and the second discharge outlet is 60-90% of the height of the tank body of the stabilization tank; the relative height difference between the feed inlet and the second discharge outlet is 50-65% of the height of the stable tank body.

10. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the stabilizing tank is provided with a feeding hole and three discharging holes; the three discharge ports are respectively marked as a first discharge port, a second discharge port and a third discharge port; wherein the feed inlet is used for receiving a second material from the ebullated bed reaction unit; the first discharge port is used for discharging a 21 st material flow, and the second discharge port is used for discharging a 22 nd material flow; a third discharge outlet for discharging a 23 rd stream; the feeding port is arranged on the tank body of the stabilizing tank, the first discharging port is arranged at the top of the stabilizing tank or at the upper part of the other side of the stabilizing tank relative to the direction of the feeding port, the second discharging port is arranged at the middle lower part of the other side of the stabilizing tank relative to the direction of the feeding port, the third discharging port is arranged at the bottom of the stabilizing tank or at the lower part of the other side of the stabilizing tank relative to the direction of the feeding port, and when the first discharging port is arranged at the upper part of the stabilizing tank, the height difference between the first discharging port and the second discharging port is 60-90% of the height of the stabilizing tank body; the relative height difference between the feeding hole and the second discharging hole is 40% -70% of the height of the stable tank body, and the relative height difference between the feeding hole and the third discharging hole is 75% -95% of the height of the stable tank body.

11. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the stabilizing tank is provided with a feeding hole and three discharging holes; the three discharge ports are respectively marked as a first discharge port, a second discharge port and a third discharge port; wherein the feed inlet is used for receiving a second material from the ebullated bed reaction unit; the first discharge port is used for discharging a 21 st material flow, and the second discharge port is used for discharging a 22 nd material flow; a third discharge outlet for discharging a 23 rd stream; the feeding port is arranged on the tank body of the stabilizing tank, the first discharging port is arranged at the top of the stabilizing tank or at the upper part of the other side of the stabilizing tank relative to the feeding port, the second discharging port is arranged at the middle lower part of the other side of the stabilizing tank relative to the feeding port, the third discharging port is arranged at the bottom of the stabilizing tank or at the lower part of the other side of the stabilizing tank relative to the feeding port, and when the first discharging port is arranged at the upper part of the stabilizing tank, the height difference between the first discharging port and the second discharging port is 60-90% of the height of the stabilizing tank; the relative height difference between the feeding hole and the second discharging hole is 50% -65% of the height of the stable tank body, and the relative height difference between the feeding hole and the third discharging hole is 80% -90% of the height of the stable tank body.

12. The ebullated bed-fixed bed composite bed hydroprocessing system according to claim 10 or 11, wherein: and a circulating pump is arranged, and the 23 rd material flow obtained by separation of the stabilizing unit is introduced to a lower seal head of the fluidized bed reactor through the circulating pump.

13. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the stabilization tank is provided with a liquid level control system, a control valve is arranged on a second discharge port pipeline of the stabilization tank, and the opening degree of the control valve on the second discharge port pipeline is correspondingly adjusted according to the liquid level in the stabilization tank.

14. The ebullated bed-fixed bed composite bed hydroprocessing system according to claim 10 or 11, wherein: the third discharge gate links to each other with the circulating pump entry, adjusts pump outlet flow through the rotational speed of control circulating pump, and then the interior liquid level of adjustment stabilization tank.

15. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the fixed bed reaction unit is provided with a plurality of fixed bed reactors in series.

16. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the fixed bed reaction unit is provided with 3-5 fixed bed reactors in series.

17. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the gas-liquid separation unit is provided with a gas-phase material flow outlet and a liquid-phase material flow outlet, and the liquid-phase material flow outlet of the gas-liquid separation unit is communicated with the inlet of the fractionation unit; the gas-liquid separation unit comprises a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator and a cold low-pressure separator; the fractionation unit includes a fractionation column.

18. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the device comprises a recycle hydrogen desulfurization tower, which is used for receiving and treating a gas phase obtained by the separation of a heat high-pressure separator in a separation unit, and the treated gas phase is used as recycle hydrogen after being boosted and is introduced into a fixed bed reaction unit and/or a boiling bed reaction unit for use.

19. The ebullated bed-fixed bed composite bed hydroprocessing system of claim 1, wherein: the first gas phase material obtained from the ebullated bed reaction unit enters the fixed bed reaction unit through a pipeline.

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