Start-up method for a combined ebullated bed-fixed bed hydrogenation plant

Abstract

The application provides a kind of ebullated bed-fixed bed combined hydrogenation device start-up method, the start-up method includes the following contents: (1) the ebullated bed hydrogenation catalyst, fixed bed hydrogenation catalyst is loaded to corresponding ebullated bed hydrogenation reactor, fixed bed hydrogenation reactor respectively;(2) from ebullated bed hydrogenation reactor hydrogen feed line, and the connecting pipeline between ebullated bed reaction unit and fixed bed reaction unit simultaneously pressurization is carried out;(3) after the gas-liquid distribution disc of ebullated bed hydrogenation reactor above and below pressure balance, hydrogen compressor is opened, and gas operation is carried out, continue to increase pressure to reaction pressure, after airtightness is qualified, raw material pump is opened, and start-up is ended.

Description

Technical Field

[0001] This invention belongs to the field of oil refining and chemical engineering, and relates to a method for starting up a hydrogenation unit, particularly a method for starting up a hydrogenation unit combining a fluidized bed and a fixed bed. Background Technology

[0002] With the increasing trend of inferior and heavy feedstocks, the shortcomings of fixed-bed residue hydrotreating technology have gradually become apparent, mainly in the following aspects: (1) Limitations in processing inferior feedstocks. Due to limitations such as catalyst activity and catalyst bed pressure drop, in order to ensure the operating 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 feedstocks with high metal content and high residual carbon content, the catalyst coking and deactivation occur quickly; at the same time, the catalyst bed is easily blocked by coke and metal organic matter, causing the pressure drop to rise rapidly; in addition, at the end of the operation, due to the uneven distribution of bed material, hot spots and radial temperature differences will also occur, ultimately leading to a shortened operating cycle of the fixed-bed unit. (2) Operating cycle and reactor pressure drop. The short operating cycle has become an important factor limiting the further development of fixed-bed residue hydrotreating technology. On the one hand, fixed-bed residue hydrotreating units suffer from low space velocity and short catalyst life, making online catalyst replacement impossible. On the other hand, during operation, as operating temperatures increase and coke deposition on the catalyst bed grows, the pressure differential and radial temperature difference in the fixed-bed catalyst bed of the protective reactor increase. This hinders further temperature increases, leading to insufficient catalyst activity in other reactors or beds, ultimately resulting in unplanned unit shutdowns and wasting corresponding catalyst activity in subsequent fixed-bed reactors. Extending the unit's operating cycle is a crucial direction for the current development of fixed-bed residue hydrotreating technology.

[0003] To extend the operating cycle of fixed-bed residue hydrotreating units, extensive research has been conducted both domestically and internationally on new process development, catalyst preparation, and gradation system research. Typical examples include the bypass reactor technology developed by UOP, the UFR protected reactor technology developed by CLG, the PRS protected reactor technology developed by IFP, and the combined fluidized bed and fixed bed hydrotreating technology developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd.

[0004] The combined fluidized bed and fixed bed hydrotreating technology leverages the advantages of fluidized bed reactors, such as complete backmixing and excellent heat and mass transfer, making them suitable as pretreatment reactors for processing low-grade residue oil. Fluidized bed reactors are typical fluidized bed reactors with significantly higher bed porosity than upflow and fixed bed reactors, resulting in greater impurity capacity. During operation, the bed pressure drop remains essentially constant, fundamentally overcoming the problem of frequent reactor shutdowns caused by pressure drop. Furthermore, because the entire reaction system is in a state of complete backmixing, the reactor exhibits excellent heat and mass transfer, eliminating hotspots caused by uneven material distribution. In addition, the complete backmixing within the fluidized bed reactor rapidly dilutes low-grade feedstock upon entry, significantly reducing system viscosity and facilitating the hydrotreating reaction. Therefore, using a fluidized bed reactor as a pretreatment reactor for low-grade residue oil offers significant technical advantages, leading to the development of a combined fluidized bed and fixed bed treatment process.

[0005] The combined fluidized bed and fixed bed hydrotreating process typically includes both a fluidized bed reactor unit and a fixed bed reactor unit. The fluidized bed reactor unit primarily removes most of the asphaltene and metals, optimizing the properties of the subsequent fixed bed feed. The fixed bed reactor unit fully utilizes the plug flow characteristics of the fixed bed reactor to perform deep hydrorefining, further improving product quality. In general, the combined fluidized bed and fixed bed hydrotreating process can solve the problems of insufficient feedstock adaptability and short operating cycles in traditional residue hydrotreating units, and is an important technology for processing low-quality residue oil with excellent application prospects. Due to the different reaction types of fluidized beds and fixed beds, ensuring stable operation of the unit is a prerequisite for the overall reaction effect. There are few research reports on start-up methods for the combined fluidized bed and fixed bed process, especially considering the characteristics of the fluidized bed reactor. Developing a safe and rapid start-up scheme is a crucial prerequisite for achieving smooth operation of the combined fluidized bed and fixed bed process technology.

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

[0007] Traditional fluidized bed reactors involve initial airtight sealing of the reactor chamber, followed by catalyst loading via oil conveying after airtight sealing is achieved. In contrast, fixed-bed residue hydrotreating units first load the catalyst, then airtighten the chamber, and only after airtight sealing is achieved do they introduce oil for heating and sulfidation. These two different reactor types result in different start-up methods for the hydrotreating process. Achieving a smooth and stable start-up in a combined fluidized bed and fixed-bed process is a challenge. To address the problems encountered during the start-up of the fluidized-fixed bed combined-bed residue hydrotreating process, the main objective of this invention is to provide a start-up method for a combined fluidized bed and fixed-bed hydrotreating unit. This method improves the operational stability of the unit and minimizes catalyst loss during the airtight sealing stage of the fluidized bed hydrotreating process.

[0008] During the research process, the applicant discovered that, as a fluidized bed reactor, the fluidized bed hydrogenation reactor requires a check valve structure on the gas-liquid distributor to prevent backflow of catalyst into the lower head of the reactor due to unexpected shutdowns during operation. This check valve effectively prevents catalyst and liquid backflow. However, when using existing start-up methods, catalyst loss still occurs. In severe cases, the check valve and even the distribution plate may deform, seriously affecting the operational safety and long-term stable operation of the unit. After analysis, the applicant believes that the root cause of this problem is the pressure difference between the top and bottom of the distribution plate during start-up. Due to the pressure and the compression between the catalyst bed, the check valve and distribution plate deform, leading to catalyst damage and leakage.

[0009] To address the aforementioned technical problems, the technical solution provided by this invention includes the following:

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

[0011] (1) The fluidized bed hydrogenation catalyst and the fixed bed hydrogenation catalyst are respectively loaded into the corresponding fluidized bed hydrogenation reactor and the fixed bed hydrogenation reactor;

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

[0013] (3) After the pressure above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor is balanced (the pressure above and below the gas-liquid distribution plate after balance does not exceed 4.0 MPa, preferably 1.5 to 4.0 MPa), start the hydrogen compressor, perform gas matching operation, continue to increase the pressure to the reaction pressure, and start the feed pump after the gas tightness is qualified, and the start-up is completed.

[0014] Furthermore, in the above-mentioned start-up method for the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, when the fluidized bed reaction unit is equipped with two or more fluidized bed hydrogenation reactors, the fluidized bed hydrogenation reactors can be arranged in parallel or in series, with series arrangement being preferred. Even further, the fluidized bed reaction unit is equipped with one or two fluidized bed hydrogenation reactors. The fluidized bed hydrogenation reactor is preferably a fluidized bed hydrogenation reactor with an internal three-phase separator, specifically, a fluidized bed hydrogenation reactor with a three-phase separator developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., as disclosed in ZL200810228414.4.

[0015] Furthermore, in the above-mentioned start-up method for the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the fixed bed reaction unit is equipped with 1 to 5 fixed bed hydrogenation reactors, preferably 2 to 4 fixed bed hydrogenation reactors. When the fixed bed reaction unit is equipped with more than 2 fixed bed hydrogenation reactors, the fixed bed hydrogenation reactors can be arranged in parallel or in series, preferably in series.

[0016] Furthermore, in the above-mentioned start-up method for the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the fixed bed hydrogenation catalyst includes, but is not limited to, one or more of the following: a fixed bed hydrogenation protection catalyst, a fixed bed hydrogenation demetallization catalyst, a fixed bed hydrogenation desulfurization catalyst, and a fixed bed hydrogenation denitrogenation catalyst. The fixed bed hydrogenation catalyst can be a commercially available product or can be prepared according to existing methods in the art; specifically, it can be the FZC series hydrogenation catalyst developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd.

[0017] Furthermore, in the above-mentioned start-up method for the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, there is no specific limitation on the shape of the fluidized bed hydrogenation catalyst; it can be spherical, cylindrical, 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 more preferably 0.4 mm to 0.8 mm. The fluidized bed hydrogenation catalyst can be a commercially available product or prepared according to existing methods in the art; specifically, it can be a fluidized bed hydrogenation catalyst developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd.

[0018] Furthermore, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the fluidized bed hydrogenation catalyst is preferably treated with an additive before being loaded into the fluidized bed hydrogenation reactor to obtain a treated fluidized bed hydrogenation catalyst. Specifically, the treatment process involves contacting the additive with the fluidized bed hydrogenation catalyst in the presence of an inert atmosphere at a temperature of 100–200°C, preferably 130–180°C; the treatment time is 2–10 hours, preferably 3–8 hours; the inert atmosphere is one or more of nitrogen, helium, neon, argon, krypton, and xenon. The additive is a sulfide, which 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 to 1.0:1, preferably 0.3 to 0.8:1.

[0019] Furthermore, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the loading method of the fluidized bed hydrogenation catalyst in step (2) is different from the existing loading method that relies on liquid-phase 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. Specifically, the fluidized bed hydrogenation catalyst can be loaded into the fluidized bed hydrogenation reactor through the feed port at the top of the fluidized bed hydrogenation reactor, adopting a loading method similar to that of the fixed bed hydrogenation catalyst.

[0020] Furthermore, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, when filling the fluidized bed hydrogenation catalyst into the fluidized bed hydrogenation reactor in step (2), the entire fluidized bed hydrogenation catalyst can be added to the fluidized bed hydrogenation reactor at once, or 60wt% to 90wt% of the total amount of fluidized bed hydrogenation catalyst can be added, preferably 70wt% to 80wt%, and the remaining fluidized bed hydrogenation catalyst can be introduced into the fluidized bed hydrogenation reactor online after start-up.

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

[0022] Furthermore, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, in step (2), the fluidized bed hydrogenation reactor is pressurized from above the gas-liquid distribution plate of the fluidized bed hydrogenation reactor. Specifically, the pressurization can be achieved through the connecting pipeline between the fluidized bed reaction unit and the fixed bed reaction unit using pipeline hydrogen, which enters the fluidized bed hydrogenation reactor and the fixed bed hydrogenation reactor respectively. Specifically, the pipeline hydrogen can be introduced into the fixed bed hydrogenation reactor and the fluidized bed hydrogenation reactor respectively through the supplementary hydrogen inlet of the first fixed bed hydrogenation reactor in the fixed bed reaction unit. The pipeline hydrogen pressure is generally 2.0 to 4.0 MPa.

[0023] Furthermore, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, the pressurization of the fluidized bed hydrogenation reactor from below the gas-liquid distribution plate in step (2) can be specifically achieved by pressurizing the fluidized bed hydrogenation reactor through the hydrogen feed pipeline of the fluidized bed hydrogenation reactor with the help of the pipeline hydrogen, and ensuring that the pressure above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor is balanced.

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

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

[0026] Furthermore, in the above-mentioned start-up method of the fluidized bed-fixed bed combined hydrogenation unit, as a preferred embodiment, when the fluidized bed reaction unit is equipped with more than two fluidized bed hydrogenation reactors, a pressurization point can be added. The new pressurization point can be set at the lower head of the fluidized bed and pressurized by instrument purging hydrogen, or it can be set at the feed hydrogen pipeline of the new fluidized bed hydrogenation reactor and pressurized by supplementary hydrogen (pipeline hydrogen) to pressurize multiple fluidized bed hydrogenation reactors respectively.

[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. This invention innovatively develops a safe and rapid start-up method for a fluidized bed-fixed bed combined hydrogenation unit. First, the fluidized bed hydrogenation reactor and the fixed bed hydrogenation reactor are pressurized by using pipeline hydrogen from the connection port. Simultaneously, the lower head of the fluidized bed hydrogenation reactor is pressurized by using instrument purging hydrogen or supplemental hydrogen (pipeline hydrogen) from the instrument purging hydrogen inlet or feed hydrogen pipeline. This ensures that the pressure on the gas-liquid distribution plate of the fluidized bed hydrogenation reactor is always balanced and that the distribution plate and its accessories do not deform, which helps to improve the safety of the unit operation.

[0029] 2. In the start-up method provided by the present invention, the pressure on the distribution plate inside the fluidized bed hydrogenation reactor is kept in a balanced state. When the system pressure rises to the same level as the pipeline hydrogen pressure, the gas is then connected according to the normal process. This reduces the disturbance to the system, reduces the amount of catalyst loss, and avoids the catalyst loss caused by gas connection under low pressure entering the subsequent fixed bed reaction unit. This is beneficial to the pressure drop control of the subsequent fixed bed section and improves the operating cycle of the entire unit.

[0030] 3. In the start-up method provided by the present invention, the fluidized bed catalyst is a catalyst pretreated with sulfur-containing additives, which increases the catalyst specific gravity, helps to reduce the amount of catalyst carried out, and can further shorten the start-up time. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the start-up method of the fluidized bed-fixed bed combined hydrogenation unit of the present invention. Detailed Implementation

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

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

[0034] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying 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 those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An 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 specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0036] In this document, all numerical values ​​for parameters (e.g., quantities or conditions) should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. Unless otherwise specified, all percentages, parts, ratios, etc., mentioned in this specification are based on weight, and pressures are gauge pressures.

[0037] In the context of this specification, any two or more embodiments of the present invention can be arbitrarily combined, and the resulting technical solutions 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 uses Figure 1The method for starting up the fluidized bed-fixed bed combined hydrogenation unit shown is as follows: the fluidized bed-fixed bed combined hydrogenation unit is equipped with one fluidized bed hydrogenation reactor and four fixed bed hydrogenation reactors. 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) Petrochemical Research Institute Co., Ltd. The specific operation process is as follows: FEM-10 spherical catalyst, developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., with an equivalent diameter of 0.4 mm, is loaded into the fluidized bed hydrogenation reactor in dry form. The loading amount is approximately 70% of the total fluidized bed hydrogenation catalyst dosage. This catalyst is pre-treated with an additive. The specific steps are: under nitrogen atmosphere, the additive FSA-55 is contacted with the fluidized bed hydrogenation catalyst. The weight ratio of the additive to the fluidized bed hydrogenation catalyst is 0.4. The treatment temperature is 140℃, and the treatment time is 6 hours. In the fixed bed hydrogenation reactor, FZC series fixed bed hydrogenation protection catalyst and fixed bed hydrogenation desulfurization catalyst, both developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., are loaded respectively. Metal catalysts, fixed-bed hydrodesulfurization catalysts, and fixed-bed hydrodenitrification catalysts, specifically including models FGF-01, FGF-02, FZC-100B, FZC-12B, FZC-103D, FZC-103E, FZC-1MN, FZC-28A, FZC-204A, FZC-33BT, and FZC-41BT hydrodesulfurization catalysts; after the catalysts in the fluidized bed hydrodesulfurization reactor and the fixed-bed hydrodesulfurization reactor are loaded, pressurization begins above and below the gas-liquid distribution plate of the fluidized bed hydrodesulfurization reactor, respectively. The pressurization point below the gas-liquid distribution plate of the fluidized bed hydrodesulfurization reactor can be set at the lower head of the fluidized bed hydrodesulfurization reactor. Hydrogen is purged using instruments to pressurize the area below the gas-liquid distribution plate of the fluidized bed hydrodesulfurization reactor. Figure 1 The initial pressurization point 1 in the text, 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. Supplementary hydrogen (pipeline hydrogen) is used to pressurize the area below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor, i.e. Figure 1 The starting pressurization point 2 in the process is used, while the pressurization point above the gas-liquid distribution plate of the fluidized bed hydrogenation reactor can be set at the supplementary hydrogen inlet of the first fixed bed hydrogenation reactor in the fixed bed reaction unit. Supplementary hydrogen (pipeline hydrogen) enters the fixed bed hydrogenation reactor and, in reverse, the fluidized bed hydrogenation reactor. Figure 1 At the start-up pressurization point 3, pressurization is carried out simultaneously above and below the gas-liquid distribution plate of the fluidized bed hydrogenation reactor, with the pressurization rate at both points not exceeding 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 (the pipeline hydrogen pressure is 4.0 MPa), gas connection operation is started, and the pressure is increased at 2.5 MPa / h to the reaction pressure of 18.0 MPa. After the airtightness is qualified, the feed pump is turned on, and the start-up is completed.

[0040] Comparative Example 1

[0041] Similar to Example 1, the difference lies in that the pressurization 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. Supplementary hydrogen (pipeline hydrogen) enters both the fixed-bed hydrogenation reactor and the fluidized-bed hydrogenation reactor in reverse. Once the reaction system pressure reaches the pipeline hydrogen pressure, gas exchange operation begins. In Comparative Example 1, pressurization is performed at the supplementary hydrogen inlet of the first fixed-bed hydrogenation reactor in the fixed-bed reaction unit. Due to the pressure, the catalyst above the gas-liquid distribution plate of the fluidized-bed hydrogenation reactor experiences backflow. This can cause blockage of the distributor and check valve on the gas-liquid distribution plate, and may also lead to deformation of the check valve and even the distribution plate. This results in uneven gas-liquid distribution, a deviation from normal fluid circulation conditions, and a large radial temperature difference in the fluidized-bed hydrogenation reactor after startup, affecting the normal operation of the unit. Table 1 compares the radial temperature differences at the first layer of temperature measurement points above the gas-liquid distribution plate of the fluidized-bed hydrogenation reactors in Example 1 and Comparative Example 1. Table 2 compares the pressure drop increase of the first fixed-bed hydrogenation reactor in Example 1 and Comparative Example 1.

[0042] Table 1 Comparison of radial temperature differences in fluidized bed hydrogenation reactors

[0043]

[0044] Table 2 Comparison of pressure drop increases in the first fixed-bed hydrogenation reactor of Example 1 and Comparative Example 1

[0045]

[0046]

[0047] As can be seen from the examples and comparative examples, the start-up method described herein can avoid the risks of uneven gas-liquid distribution in the fluidized bed hydrogenation reactor and the large-scale introduction of fluidized bed hydrogenation catalyst into the subsequent fixed bed. The device will not experience local hot spots or rapid pressure drop, and the normal start-up of the device can be guaranteed. Therefore, the start-up method described herein is superior to the traditional start-up method.

Claims

1. A start-up method of an ebullated bed-fixed bed combined hydrogenation device, the ebullated bed-fixed bed combined hydrogenation device comprising an ebullated bed reaction unit and a fixed bed reaction unit, the ebullated bed reaction unit being provided with at least one ebullated bed hydrogenation reactor, and the fixed bed reaction unit being provided with at least one fixed bed hydrogenation reactor; the start-up method comprising the following steps: (1) loading ebullated bed hydrogenation catalyst and fixed bed hydrogenation catalyst into corresponding ebullated bed hydrogenation reactors and fixed bed hydrogenation reactors, respectively; (2) simultaneously pressurizing the ebullated bed hydrogenation reactors from above and below the gas-liquid distribution tray of the ebullated bed hydrogenation reactors; (3) after the pressure above and below the gas-liquid distribution tray of the ebullated bed hydrogenation reactors is balanced, starting the hydrogen compressor, performing parallel gas operation, continuously increasing the pressure to the reaction pressure, and after the airtightness is qualified, starting the raw material pump, and ending the start-up. 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; the ebullated bed hydrogenation reactor is an ebullated bed hydrogenation reactor provided with a three-phase separator inside the reactor. The ebullated bed hydrogenation reactors are arranged in series. The fixed bed hydrogenation catalyst includes, but is not limited to, one or more of fixed bed hydrogenation guard catalyst, fixed bed hydrogenation demetallization catalyst, fixed bed hydrogenation desulfurization catalyst, and fixed bed hydrogenation denitrification catalyst.

2. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 1, characterized in that: The equivalent diameter of the ebullated bed hydrogenation catalyst is 0.3 mm to 2.5 mm.

3. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 2, characterized in that: The equivalent diameter of the ebullated bed hydrogenation catalyst is 0.4 mm to 1.5 mm.

4. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 1, characterized in that: The equivalent diameter of the ebullated bed hydrogenation catalyst is 0.4 mm to 0.8 mm.

5. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 1, characterized in that: The ebullated bed hydrogenation catalyst is treated with an additive before being loaded into the ebullated bed hydrogenation reactor to obtain treated ebullated bed hydrogenation catalyst; the treatment process is performed by contacting the additive with the ebullated bed hydrogenation catalyst in the presence of an inert atmosphere, the treatment temperature is 100 to 200°C, and the treatment time is 2 to 10 h; the additive is a sulfide.

6. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 1, characterized in that: The ebullated bed hydrogenation catalyst is treated with an additive before being loaded into the ebullated bed hydrogenation reactor to obtain treated ebullated bed hydrogenation catalyst; the treatment process is performed by contacting the additive with the ebullated bed hydrogenation catalyst in the presence of an inert atmosphere, the treatment temperature is 130 to 180°C, and the treatment time is 3 to 8 h; the additive is a sulfide.

7. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus 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 additive to the ebullated bed hydrogenation catalyst is 0.1 to 1.0:

1.

8. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 1, characterized in that: The weight ratio of the additive to the ebullated bed hydrogenation catalyst is 0.3 to 0.8:

1.

9. The operating method of an ebullated bed-fixed bed combined hydrogenation apparatus according to claim 1, characterized in that: In step (1), the ebullated bed hydrogenation catalyst is directly added to the ebullated bed hydrogenation reactor in a dry agent state.

10. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 8 or 9, characterized in that: ​ 11. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 10, characterized in that: ​ 12. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: ​ 13. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (1), when the ebullated-bed hydrogenation catalyst is loaded into the ebullated-bed hydrogenation reactor, the ebullated-bed hydrogenation catalyst is added into the ebullated-bed hydrogenation reactor at one time, or 60wt%-90wt% 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 start-up.

14. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (1), when the ebullated-bed hydrogenation catalyst is loaded into the ebullated-bed hydrogenation reactor, the ebullated-bed hydrogenation catalyst is added into the ebullated-bed hydrogenation reactor at one time, or 60wt%-90wt% 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 start-up.

15. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (2), the ebullated-bed hydrogenation reactor is pressurized by means of the hydrogen in the pipe network and / or the instrument purging hydrogen.

16. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (2), the ebullated-bed hydrogenation reactor is pressurized from above the gas-liquid distribution plate of the ebullated-bed hydrogenation reactor by means of the hydrogen in the connecting pipeline between the ebullated-bed reaction unit and the fixed-bed reaction unit, which enters the ebullated-bed hydrogenation reactor and the fixed-bed hydrogenation reactor, respectively, and enters the fixed-bed hydrogenation reactor and the ebullated-bed hydrogenation reactor in the reverse direction by means of the hydrogen in the supplementary hydrogen inlet of the first fixed-bed hydrogenation reactor in the fixed-bed reaction unit.

17. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (2), the ebullated-bed hydrogenation reactor is pressurized from below the gas-liquid distribution plate of the ebullated-bed hydrogenation reactor by means of the hydrogen in the hydrogen feeding pipeline of the ebullated-bed hydrogenation reactor, and the pressure above and below the gas-liquid distribution plate of the ebullated-bed hydrogenation reactor is balanced.

18. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (2), the ebullated-bed hydrogenation reactor is pressurized by means of the instrument purging hydrogen, and the ebullated-bed hydrogenation reactor is pressurized from above and below the gas-liquid distribution plate of the ebullated-bed hydrogenation reactor at the same time.

19. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: In step (3), the reaction pressure is 12.0-30.0 MPa, and the pressure is pressurized by means of the hydrogen compressor.

20. The operating process for a combined ebullated bed-fixed bed hydrogenation plant according to claim 1, characterized in that: In step (3), the reaction pressure is 15.0-20.0 MPa. The pressure is pressurized by means of the hydrogen compressor.

21. The operating method of an ebullated bed-fixed bed combined hydrogenation plant according to claim 1, characterized in that: When the ebullated-bed reaction unit is provided with two or more ebullated-bed hydrogenation reactors, a pressurizing point is added, the new pressurizing point is arranged at the lower head of the ebullated-bed hydrogenation reactor, and the pressure is pressurized by means of the instrument purging hydrogen, or the new pressurizing point is arranged at the hydrogen feeding pipeline of the new ebullated-bed hydrogenation reactor, and the pressure is pressurized by means of the supplementary hydrogen.

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