Boiling bed-fixed bed combined hydrogenation device starting method

Abstract

The invention provides a start-up method of a fluidized bed-fixed bed combined hydrogenation device. The start-up method comprises the following steps: (1) respectively filling a fluidized bed hydrogenation reactor and a fixed bed hydrogenation reactor with a fluidized bed hydrogenation catalyst and a fixed bed hydrogenation catalyst; (2) pressurizing from a hydrogen feeding pipeline of the fluidized bed hydrogenation reactor and a connecting pipeline between the fluidized bed reaction unit and the fixed bed reaction unit at the same time; and (3) after the pressure above and below the gas-liquid distribution disc of the fluidized bed hydrogenation reactor is balanced, starting a hydrogen compressor, carrying out gas merging operation, continuously increasing the pressure until the reaction pressure is reached, starting a raw material pump after the airtightness is qualified, and ending the operation.

Description

Technical Field

[0001] The present invention belongs to the field of oil refining and chemical engineering, and relates to a method for starting up a hydrogenation unit, in particular to a method for starting up a combined fluidized bed and fixed bed hydrogenation unit. Background Art

[0002] With the increasing trend of raw material inferiority and heaviness, the deficiencies of fixed bed residue hydrogenation technology have gradually emerged, mainly manifested in the following aspects: (1) Limitations in processing inferior raw materials. Limited by factors such as catalyst activity and catalyst bed pressure drop, to ensure the operation cycle of the unit, it is usually necessary to control the total metal content of the fixed bed feedstock oil to be less than 150 μg / g, the residual carbon to be less than 15%, and the asphaltene content to be less than 5%. When using fixed bed technology to process inferior raw materials with high metals and high residual carbon, the catalyst cokes and deactivates quickly; at the same time, the catalyst bed is easily blocked by coke and metal organic compounds, resulting in a rapid increase in pressure drop; in addition, at the end of operation, due to uneven distribution of bed layer logistics, problems such as bed layer hot spots and radial temperature differences will also occur, ultimately leading to a shortened operation cycle of the fixed bed unit. (2) Operation cycle and reactor pressure drop. The relatively short operation cycle has become an important factor restricting the further development of fixed bed residue hydrogenation technology. On the one hand, the space velocity of the fixed bed residue hydrogenation unit is low and the catalyst life is short, and the catalyst cannot be replaced online; on the other hand, during operation, as the operating temperature increases and the amount of coke deposited on the catalyst bed increases, phenomena such as an increase in pressure difference and radial temperature difference will occur in the fixed bed catalyst bed of the protection reactor, affecting the continued temperature increase of the unit, and then resulting in the insufficient utilization of the catalyst activity of other reactors or bed layers, ultimately leading to unplanned shutdown of the unit and wasting the corresponding catalyst activity in the subsequent fixed bed reactors. Extending the operation cycle of the unit is an important direction for the development of fixed bed residue hydrogenation technology.

[0003] To extend the operation cycle of fixed bed residue hydrogenation units, a large amount of research work has been carried out at home and abroad in aspects such as new process development, catalyst preparation, and grading system research. Among them, typical ones include the bypass reactor technology developed by UOP, the UFR protection reactor technology developed by CLG, the PRS protection reactor technology developed by IFP, and the combined fluidized bed and fixed bed hydrogenation technology developed by Sinopec (Dalian) Research Institute of Petroleum and Chemical Industry.

[0004] The combination hydrotreating technology of fluidized bed and fixed bed utilizes the advantages of the fluidized bed reactor, such as complete backmixing and good heat and mass transfer effects, making it a pretreatment reactor for processing inferior residue oil. The fluidized bed reactor is a typical fluidized bed reactor, with a bed porosity much higher than that of upflow reactors and fixed bed reactors, and a higher impurity accommodation capacity than upflow reactors and traditional fixed bed reactors. During operation, the bed pressure drop basically remains constant, fundamentally overcoming the problem of frequent shutdowns of the protection reactor caused by the bed pressure drop. At the same time, since the entire reaction system is in a state of complete backmixing, the heat and mass transfer effects of the reactor are very good, and there are no problems such as hot spots caused by uneven material distribution. In addition, the inside of the fluidized bed reactor is in a state of complete backmixing. After the inferior raw material enters the reactor, it will be quickly diluted, and the viscosity of the system will drop significantly, which is helpful for the hydrotreating reaction to proceed. Therefore, using a fluidized bed reactor as a pretreatment reactor for inferior residue oil has strong technical advantages. Based on this, a combined treatment process of fluidized bed and fixed bed has been developed.

[0005] The combined hydrotreating process of fluidized bed and fixed bed generally includes a fluidized bed reaction unit and a fixed bed reaction unit. The fluidized bed reaction unit mainly undertakes the function of removing most of the asphaltenes and metals, playing a role in optimizing the properties of the subsequent fixed bed feed; the fixed bed reaction unit gives full play to the characteristics of plug flow of the fixed bed reactor and undertakes the function of deep hydrofining to further improve the product quality. Generally speaking, the combined hydrotreating process of fluidized bed and fixed bed can solve problems such as insufficient raw material adaptability and short operation cycle of traditional residue hydrotreating units, and is an important technology for processing inferior residue oil in the future, with good application prospects. Due to the different reaction types of the fluidized bed and the fixed bed, how to ensure the stable startup of the device is a prerequisite for affecting the reaction effect of the entire system. There are few research reports on the startup methods for the fluidized bed-fixed bed combined process in the existing technology. Especially on the premise of fully considering the characteristics of the fluidized bed as a fluidized bed reactor, developing a safe and fast startup scheme is an important prerequisite for the fluidized bed-fixed bed combined process technology to achieve smooth startup.

[0006] Patent CN108070402A discloses a startup method for a combined process of fluidized bed and fixed bed. The main technical feature is to load the catalyst from the top into the fluidized bed reactor and the fixed bed reactor, pressurize the connecting pipeline between the fluidized bed and the fixed bed to increase the pressure, and the pressure penetrates forward through the fluidized bed reactor and backward through the fixed bed reactor respectively. After rising to the pressure required for the reaction, the startup oil enters from the pipeline between the fluidized bed and the fixed bed, and enters the fluidized bed reactor and the fixed bed reactor respectively for catalyst wetting. After the catalyst is wetted, the startup of the reactor is completed, and the device operates normally. Summary of the Invention

[0007] The traditional fluidized bed reactor fills the catalyst in the way of first conducting airtight test on the empty cylinder, and after passing the airtight test, transporting the catalyst with the conveying oil. While for the fixed bed residue hydrotreating unit, the catalyst is filled first, then the airtight test is carried out. After passing the airtight test, the oil is fed in and the temperature is raised for sulfidation. The start-up methods of the hydrogenation processes using two different types of reactors are different. How to achieve a smooth start-up in the fluidized bed and fixed bed combined process has become a difficult problem. Aiming at the problems existing in the start-up of the fluidized bed-fixed bed combined residue hydrotreating process, the main purpose of the present invention is to provide a start-up method for a fluidized bed-fixed bed combined hydrogenation unit. The provided start-up method can improve the operation stability of the unit, and at the same time, maximize the avoidance of the loss of the fluidized bed hydrogenation catalyst during the airtight stage.

[0008] During the research process, the applicant found that as a fluidized bed reactor, in order to avoid the catalyst filled inside the fluidized bed hydrogenation reactor flowing back into the lower head of the reactor due to an accidental shutdown during operation, a check structure is provided on the gas-liquid distributor inside the fluidized bed hydrogenation reactor. The check structure can effectively prevent the backflow of the catalyst and liquid. However, when using the existing start-up method, there is still a phenomenon of catalyst loss. In severe cases, the check valve and even the distribution plate will show a certain degree of deformation, seriously affecting the operation safety and long-term stable operation of the unit. After research and analysis, the applicant believes that the root cause of this problem should be the different pressures above and below the distribution plate during the start-up process. Due to the extrusion between the pressure and the catalyst bed, the check valve and the distribution plate are deformed, and the catalyst is damaged and leaks.

[0009] Aiming at the above technical problems, the technical solutions provided by the present invention include the following content:

[0010] The present invention provides a start-up method for a fluidized bed-fixed bed combined hydrogenation unit. The fluidized bed-fixed bed combined hydrogenation unit includes a fluidized bed reaction unit and a fixed bed reaction unit. The fluidized bed reaction unit is provided with at least one fluidized bed hydrogenation reactor, and the fixed bed reaction unit is provided with at least one fixed bed hydrogenation reactor. The start-up method includes the following content:

[0011] (1) Fill the fluidized bed hydrogenation catalyst and the fixed bed hydrogenation catalyst into the corresponding fluidized bed hydrogenation reactor and fixed bed hydrogenation reactor respectively.

[0012] (2) Pressurize the fluidized bed reactor simultaneously from above and below the gas-liquid distributor of the fluidized bed hydrogenation reactor.

[0013] (3) After the pressures above and below the gas-liquid distributor of the fluidized bed hydrogenation reactor are balanced (the pressures above and below the gas-liquid distributor after balance do not exceed 4.0 MPa, preferably 1.5 - 4.0 MPa), start the hydrogen compressor, conduct the gas combination operation, continue to increase the pressure to the reaction pressure, and start the raw material pump after passing the airtight test to end the start-up.

[0014] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, when more than 2 fluidized bed hydrogenation reactors are provided in the fluidized bed reaction unit, the fluidized bed hydrogenation reactors can be arranged in parallel or in series, and series arrangement is preferably adopted. Further, 1 or 2 fluidized bed hydrogenation reactors are provided in the fluidized bed reaction unit. The fluidized bed reactor is preferably a fluidized bed reactor with a three-phase separator provided inside the reactor. Specifically, a fluidized bed reactor with a three-phase separator developed by SINOPEC (Dalian) Research Institute of Petroleum and Chemical Industry can be used, such as the structure disclosed in ZL200810228414.4.

[0015] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, 1 to 5 fixed bed hydrogenation reactors are provided in the fixed bed reaction unit, and preferably 2 to 4 fixed bed hydrogenation reactors are provided. When more than 2 fixed bed hydrogenation reactors are provided in the fixed bed reaction unit, the fixed bed hydrogenation reactors can be arranged in parallel or in series, and series arrangement is preferably adopted.

[0016] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, the fixed bed hydrogenation catalyst includes but is not limited to one or several of a fixed bed hydrogenation protection catalyst, a fixed bed hydrodemetallization catalyst, a fixed bed hydrodesulfurization catalyst, and a fixed bed hydrodenitrogenation catalyst. The fixed bed hydrogenation catalyst can be a commercially available product or can be prepared according to the existing methods in the art. Specifically, the FZC series of hydrogenation catalysts developed by SINOPEC (Dalian) Research Institute of Petroleum and Chemical Industry can be used.

[0017] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, there is no specific limitation on the shape of the fluidized bed hydrogenation catalyst, and it can be spherical, cylindrical strip-shaped, clover-shaped, etc. The equivalent diameter of the fluidized bed hydrogenation catalyst is 0.3 mm to 2.5 mm, preferably 0.4 mm to 1.5 mm, and further preferably 0.4 mm to 0.8 mm. The fluidized bed hydrogenation catalyst can be a commercially available product or can be prepared according to the existing methods in the art. Specifically, it can be the fluidized bed hydrogenation catalyst developed by SINOPEC (Dalian) Research Institute of Petroleum and Chemical Industry.

[0018] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, before loading the fluidized bed hydrogenation catalyst into the fluidized bed hydrogenation reactor, it is preferred to treat the fluidized bed hydrogenation catalyst with an additive to obtain the treated fluidized bed hydrogenation catalyst. The specific treatment process is to contact the additive with the fluidized bed hydrogenation catalyst under the condition of an inert atmosphere. The treatment temperature is 100-200°C, preferably 130-180°C; the treatment time is 2-10 h, preferably 3-8 h; the inert atmosphere is one or more of nitrogen, helium, neon, argon, krypton, and xenon. The additive is a sulfide, and the sulfide is one or more of dimethyl sulfide, n-butyl mercaptan, carbon disulfide, dimethyl disulfide, SZ-54, and FSA-55; the weight ratio of the additive to the fluidized bed hydrogenation catalyst is 0.1-1.0:1, preferably 0.3-0.8:1.

[0019] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, the loading method of the fluidized bed hydrogenation catalyst in step (2) is different from the existing loading method that relies on the liquid-phase raw material feed to bring the fluidized bed hydrogenation catalyst into the reactor. In step (2), the fluidized bed hydrogenation catalyst is directly added to the fluidized bed hydrogenation reactor in a dry state, and specifically, the fluidized bed hydrogenation catalyst can be loaded into the fluidized bed hydrogenation reactor through the top feed port of the fluidized bed hydrogenation reactor, adopting a loading method similar to that of the fixed bed hydrogenation catalyst.

[0020] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, when loading the fluidized bed hydrogenation catalyst into the fluidized bed hydrogenation reactor in step (2), the fluidized bed hydrogenation catalyst can be added to the fluidized bed hydrogenation reactor all at once, or 60 wt% - 90 wt%, preferably 70 wt% - 80 wt% of the total amount of the fluidized bed hydrogenation catalyst to be loaded can be loaded, and the remaining fluidized bed hydrogenation catalyst is introduced into the fluidized bed hydrogenation reactor in an on-line addition manner after start-up.

[0021] Further, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred implementation, the pressurization of the fluidized bed reactor in step (2) can be carried out by means of network hydrogen and / or instrument purge hydrogen.

[0022] Further, in the start-up method of the above fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the pressurization of the fluidized bed reactor from above the gas-liquid distribution tray of the fluidized bed hydrogenation reactor can be specifically carried out by using network hydrogen through the connecting pipeline between the fluidized bed reaction unit and the fixed bed reaction unit, and respectively enter the fluidized bed hydrogenation reactor and the fixed bed hydrogenation reactor. Specifically, it can enter the fixed bed reactor and reverse into the fluidized bed reactor from the make-up hydrogen inlet of the first fixed bed hydrogenation reactor in the fixed bed reaction unit by using network hydrogen through this make-up port. The pressure of the network hydrogen is generally 2.0 - 4.0 MPa.

[0023] Further, in the start-up method of the above fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the pressurization of the fluidized bed reactor from below the gas-liquid distribution tray of the fluidized bed hydrogenation reactor can be specifically carried out by using network hydrogen through the hydrogen feed pipeline of the fluidized bed hydrogenation reactor, and ensure the pressure balance above and below the gas-liquid distribution tray of the fluidized bed reactor.

[0024] Further, in the start-up method of the above fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the pressurization of the fluidized bed reactor in step (2) can also be carried out by using instrument purge hydrogen (in order to prevent heavy oil materials from entering the instrument casing and coking in the instrument casing, a pressurized hydrogen is introduced into the instrument casing, and this hydrogen is the instrument purge hydrogen) to pressurize the fluidized bed reactor simultaneously from above and below the gas-liquid distribution tray of the fluidized bed hydrogenation reactor.

[0025] Further, in the start-up method of the above fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the reaction pressure in step (3) is 12.0 - 30.0 MPa, preferably 15.0 - 20.0 MPa; generally, pressurization is carried out by using a hydrogen compressor.

[0026] Further, in the start-up method of the above fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, when there are two or more fluidized bed hydrogenation reactors in the fluidized bed reaction unit, the pressurization points can be increased. The newly added pressurization points can be set at the lower head of the fluidized bed and pressurized by using instrument purge hydrogen, or can be set at the feed hydrogen pipeline of the newly added fluidized bed hydrogenation reactor, and multiple fluidized bed reactors can be pressurized respectively by using make-up hydrogen (network hydrogen).

[0027] Compared with the prior art, the start-up method of the fluidized bed-fixed bed combined hydrogenation unit provided by the present invention has the following advantages:

[0028] 1. The present invention originally develops a safe and fast start-up method for a fluidized bed-fixed bed combined hydrogenation device. First, pressurization is carried out through the connection port between the fluidized bed reactor and the fixed bed reactor by means of network hydrogen. At the same time, pressurization of the lower head of the fluidized bed reactor is carried out through the instrument purge hydrogen inlet or the feed hydrogen pipeline of the fluidized bed hydrogenation reactor by means of instrument purge hydrogen or supplementary hydrogen (network hydrogen), ensuring that the pressure above and below the gas-liquid distribution plate of the fluidized bed reactor is always balanced and the distribution plate and its accessories do not deform, which is beneficial to improving the operation safety of the device.

[0029] 2. In the start-up method provided by the present invention, the pressure above and below the distribution plate in the fluidized bed reactor remains in a balanced state. When the system pressure rises to the same as the network hydrogen pressure, then the gas merging is carried out according to the normal process, the disturbance to the system is reduced, the catalyst loss is decreased, and the catalyst loss caused by gas merging under low pressure entering the subsequent fixed bed reaction unit is avoided, which is beneficial to the pressure drop control of the subsequent fixed bed part and improves the operation cycle of the whole device.

[0030] 3. In the start-up method provided by the present invention, the fluidized bed catalyst is the catalyst pretreated with a sulfur-containing promoter, which increases the catalyst specific gravity, helps to reduce the catalyst carry-out amount, and at the same time, can further shorten the start-up time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the start-up method for the fluidized bed-fixed bed combined hydrogenation device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The following will describe in detail the specific embodiments of the present invention in conjunction with the drawings and specific examples. However, it should be noted that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the claims.

[0033] Unless otherwise clearly stated, throughout the specification and claims, the term "comprise" or its variations such as "comprises" or "comprising" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0034] In this document, for convenience of description, spatial relative terms such as "below", "beneath", "under", "above", "over", "on", etc. may be used to describe the relationship of one element or feature to another element or feature in the drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation in addition to the orientation depicted in the figures. For example, if an object in the figures is flipped, an element described as "below" or "under" another element or feature will be oriented "above" the element or feature. Thus, the exemplary term "below" can encompass both the direction of below and above. The object may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0035] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to define a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. may also be interchanged with each other.

[0036] In this document, all numerical values of parameters (e.g., quantities or conditions) should be understood to be modified in all instances by the term "about", whether or not the term "about" actually appears before the numerical value. Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are by weight, and the pressure is gauge pressure.

[0037] In the context of this specification, any two or more embodiments of the present invention can be combined arbitrarily, and the technical solutions thus formed are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0038] Example 1

[0039] Example 1 adopts Figure 1Start-up method of the fluidized bed-fixed bed combined hydrogenation unit shown. In the fluidized bed-fixed bed combined hydrogenation unit, 1 fluidized bed hydrogenation reactor and 4 fixed bed hydrogenation reactors are provided. The fixed bed hydrogenation reactors are connected in series. The fluidized bed hydrogenation reactor is a fluidized bed hydrogenation reactor with a three-phase separator developed by Sinopec (Dalian) Research Institute of Petroleum and Chemical Industry Co., Ltd. The specific operation process is as follows: Fill the fluidized bed hydrogenation reactor with the FEM-10 spherical catalyst developed by Sinopec (Dalian) Research Institute of Petroleum and Chemical Industry Co., Ltd. in the form of dry agent. The equivalent diameter is 0.4 mm, and the filling amount is about 70% of the total dosage of the fluidized bed hydrogenation catalyst. This catalyst is pre-treated with an additive. The specific steps are as follows: In the presence of nitrogen, contact the additive FSA-55 with the fluidized bed hydrogenation catalyst. The addition amount of the additive is in a weight ratio of 0.4 to the fluidized bed hydrogenation catalyst. The treatment temperature is 140 °C, and the treatment time is 6 h. Fill the fixed bed hydrogenation reactors with the fixed bed hydrogenation protection catalyst, fixed bed hydrogenation demetallization catalyst, fixed bed hydrogenation desulfurization catalyst, and fixed bed hydrogenation denitrification catalyst of the FZC series developed by Sinopec (Dalian) Research Institute of Petroleum and Chemical Industry Co., Ltd., specifically including hydrogenation catalysts of models FGF-01, FGF-02, FZC-100B, FZC-12B, FZC-103D, FZC-103E, FZC-1MN, FZC-28A, FZC-204A, FZC-33BT, FZC-41BT. After the catalysts in the fluidized bed hydrogenation reactor and the fixed bed hydrogenation reactors are filled, start pressurizing above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor respectively. The pressurization point below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor can be set at the lower head of the fluidized bed hydrogenation reactor. Use instrument purging hydrogen to pressurize below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor, that is Figure 1 the start-up pressurization point 1 in Figure 1 . The pressurization point below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor can also include the feed hydrogen pipeline of the fluidized bed hydrogenation reactor. Use make-up hydrogen (network hydrogen) to pressurize below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor, that is Figure 1 the start-up pressurization point 2 in Figure 1 . And the pressurization point above the gas-liquid distribution plate of the fluidized bed hydrogenation reactor can be set at the make-up hydrogen inlet of the first fixed bed hydrogenation reactor in the fixed bed reaction unit. Use make-up hydrogen (network hydrogen) to enter the fixed bed hydrogenation reactor respectively and enter the fluidized bed hydrogenation reactor reversely, that is Figure 1 the start-up pressurization point 3 shown in Figure 1 . Pressurize above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor simultaneously. The pressurization speed at both places is not higher than 0.5 MPa / h. After the pressure above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor reaches 4.0 MPa (network hydrogen pressure 4.0 MPa), start the merging operation. Raise the pressure to the reaction pressure of 18.0 MPa at a rate of 2.5 MPa / h. After passing the airtightness test, start the feed pump, and the start-up is completed.

[0040] Comparative Example 1

[0041] It is basically the same as Example 1, except that the pressure charging point of the reaction system is only set at the supplementary hydrogen inlet of the first fixed-bed hydrogenation reactor in the fixed-bed reaction unit. The supplementary hydrogen (network hydrogen) is used to enter the fixed-bed hydrogenation reactor respectively and enter the ebullated-bed hydrogenation reactor reversely. When the pressure of the reaction system reaches the network hydrogen pressure, the gas merging operation is started. In Comparative Example 1, when pressurizing at the supplementary hydrogen inlet of the first fixed-bed hydrogenation reactor in the fixed-bed reaction unit, due to the pressure effect, the catalyst above the gas-liquid distribution tray in the ebullated-bed hydrogenation reactor backflows. On the one hand, it blocks the distributor and the check structure on the gas-liquid distribution tray in the ebullated-bed hydrogenation reactor. On the other hand, it may cause the deformation of the check structure and even the distribution tray, resulting in uneven gas-liquid distribution, deviation of the fluid circulation state from the normal operating condition, and relatively large radial temperature difference in the ebullated-bed hydrogenation reactor after startup, affecting the normal operation of the device. Table 1 compares the radial temperature differences at the first temperature measurement point above the gas-liquid distribution tray in the ebullated-bed hydrogenation reactors of Example 1 and Comparative Example 1. Table 2 compares the increase in pressure drop of the first fixed-bed hydrogenation reactor in Example 1 and Comparative Example 1.

[0042] Table 1 Comparison of Radial Temperature Differences in Ebullated-Bed Hydrogenation Reactors

[0043]

[0044] Table 2 Comparison of the Increase in Pressure Drop of the First Fixed-Bed Hydrogenation Reactor in Example 1 and Comparative Example 1

[0045]

[0046]

[0047] It can be found from the examples and comparative examples that starting up using the starting-up method described in this article can avoid the risks of uneven gas-liquid distribution in the ebullated-bed reactor and a large amount of ebullated-bed catalyst being carried into the subsequent fixed-bed. The device will not show local hot spots and a rapid increase in pressure drop, and can ensure the normal start-up of the device. Thus, it can be seen that the starting-up method described in this article is superior to the traditional starting-up method.

Claims

1. A method for starting up an ebullated bed-fixed bed combined hydrogenation device, wherein the ebullated bed-fixed bed combined hydrogenation device comprises an ebullated bed reaction unit and a fixed bed reaction unit, wherein the ebullated bed reaction unit is provided with at least one ebullated bed hydrogenation reactor, and the fixed bed reaction unit is provided with at least one fixed bed hydrogenation reactor; the method for starting up comprises the following contents: (1) Loading an ebullated bed hydrogenation catalyst and a fixed bed hydrogenation catalyst into a corresponding ebullated bed hydrogenation reactor and a fixed bed hydrogenation reactor respectively; (2) Pressurizing the ebullated bed hydrogenation reactor simultaneously from above and below the gas-liquid distribution plate of the ebullated bed hydrogenation reactor; (3) After the pressure above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor is balanced, start the hydrogen compressor to perform the gas mixing operation, continue to increase the pressure to the reaction pressure, and start the raw material pump after the airtightness is qualified, and the start-up is completed.

2. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: When the ebullated bed reaction unit is provided with two or more ebullated bed hydrogenation reactors, the ebullated bed hydrogenation reactors are arranged in parallel or in series, preferably in series; the ebullated bed reactor is an ebullated bed reactor with a three-phase separator arranged inside the reactor.

3. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: The fixed bed hydrogenation catalyst includes but is not limited to one or more of a fixed bed hydrogenation protection catalyst, a fixed bed hydrodemetallization catalyst, a fixed bed hydrodesulfurization catalyst, and a fixed bed hydrodenitrogenation catalyst.

4. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: The equivalent diameter of the ebullated bed hydrogenation catalyst is 0.3 mm to 2.5 mm, preferably 0.4 mm to 1.5 mm, and more preferably 0.4 mm to 0.8 mm.

5. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: The ebullated bed hydrogenation catalyst is treated with an auxiliary agent before loading the ebullated bed hydrogenation reactor to obtain a treated ebullated bed hydrogenation catalyst; the treatment process is to contact the auxiliary agent with the ebullated bed hydrogenation catalyst for treatment under the condition of inert atmosphere, the treatment temperature is 100-200°C, preferably the treatment temperature is 130-180°C; the treatment time is 2-10h, preferably the treatment time is 3-8h; the auxiliary agent is sulfide.

6. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: The sulfide is one or more of dimethyl sulfide, n-butyl mercaptan, carbon disulfide, dimethyl disulfide, SZ-54 and FSA-55; the weight ratio of the added amount of the auxiliary agent to the ebullating bed hydrogenation catalyst is 0.1-1.0:1, preferably 0.3-0.8:

1.

7. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: In step (1), the ebullated bed hydrogenation catalyst is directly added into the ebullated bed hydrogenation reactor in a dry state.

8. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: When the ebullated bed hydrogenation catalyst is loaded into the ebullated bed hydrogenation reactor in step (1), the ebullated bed hydrogenation catalyst is added to the ebullated bed hydrogenation reactor all at once, or 60 wt% to 90 wt%, preferably 70 wt% to 80 wt% of the total amount of the ebullated bed hydrogenation catalyst is loaded, and the remaining ebullated bed hydrogenation catalyst is introduced into the ebullated bed hydrogenation reactor in an online manner after the operation is started.

9. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: In step (2), the fluidized bed reactor is pressurized with the aid of pipeline hydrogen and / or instrument purge hydrogen.

10. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: In step (2), the ebullated bed reactor is pressurized from above the gas-liquid distribution plate of the ebullated bed hydrogenation reactor through the connecting pipeline between the ebullated bed reaction unit and the fixed bed reaction unit with the help of pipeline network hydrogen, and enters the ebullated bed hydrogenation reactor and the fixed bed hydrogenation reactor respectively, and enters the fixed bed reactor and reversely enters the ebullated bed reactor through the supplementary hydrogen inlet of the first fixed bed hydrogenation reactor in the fixed bed reaction unit with pipeline network hydrogen with the help of this supplementary port.

11. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: In step (2), the ebullated bed reactor is pressurized from below the gas-liquid distribution plate of the ebullated bed hydrogenation reactor by means of the hydrogen feed line of the ebullated bed hydrogenation reactor with the aid of network hydrogen, and the pressure above and below the gas-liquid distribution plate of the ebullated bed reactor is balanced.

12. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: In step (2), the ebullated bed reactor is pressurized by blowing hydrogen through the upper and lower gas-liquid distribution plate of the ebullated bed hydrogenation reactor with the aid of an instrument to simultaneously pressurize the ebullated bed reactor.

13. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: The reaction pressure in step (3) is 12.0 to 30.0 MPa, preferably 15.0 to 20.0 MPa; the pressure is generally charged with the aid of a hydrogen compressor.

14. The method for starting up a fluidized bed-fixed bed combined hydrogenation unit according to claim 1, characterized in that: When the fluidized bed reaction unit is equipped with more than two fluidized bed hydrogenation reactors, a charging point is added. The newly added charging point is set at the lower head of the fluidized bed, and the hydrogen is purged by the instrument for pressurization, or it is set at the feed hydrogen pipeline of the newly added fluidized bed hydrogenation reactor, and the multiple fluidized bed reactors are pressurized separately with supplementary hydrogen.

Images