A process for catalyst management and cycle extension in a fixed bed reactor based on multi-side-line feed switching

Abstract

The application discloses a kind of fixed bed reactor catalyst management and running cycle extension process based on multiple side line feeding switching, and relates to chemical technology field.The process is applied to multiple bed layers, multiple feed inlet fixed bed reactor, comprising: reaction raw materials enter and pass through all bed layers from first feed inlet;Real-time monitoring the most upstream bed layer pressure drop;When pressure rises to preset threshold, feed inlet is switched to the second feed inlet downstream, so that raw materials bypass the upstream bed layer that has been blocked;Further according to the switching of pressure drop monitoring results to more downstream feed inlet.The application switches the feed inlet dynamically, changes the inactivation of catalyst bed layer from synchronous bearing to sequential bearing, actively manages the catalyst inactivation process, thereby effectively extends the device running cycle without shutdown, and improves the catalyst utilization rate, especially suitable for processing poor quality raw materials that can easily cause the rapid rise of bed layer pressure drop.

Description

Technical Field

[0001] This invention relates to the fields of petrochemical, coal chemical and fine chemical technology, and specifically to a catalyst management and operation process for fixed-bed hydrogenation reactors (such as hydrorefining, hydrocracking and hydroisomerization reactors), which is particularly suitable for treating inferior raw materials that are prone to causing a rapid increase in catalyst bed pressure drop. Background Technology

[0002] A fixed-bed hydrogenation reactor is a core heterogeneous catalytic reaction device. Its core feature is that solid catalyst particles are statically packed inside the reactor to form a fixed bed, through which gaseous or liquid reactants (containing hydrogen) continuously flow. The hydrogenation reaction takes place on the catalyst surface. It is the most widely used hydrogenation unit in petroleum refining and chemical synthesis.

[0003] Related patents, such as CN119425528A, involve a premixed inlet diffuser and a fixed-bed hydrogenation reactor, including a diffuser body, a diffusion assembly, and a distribution assembly. The diffuser body includes a mixing chamber and an inlet and an outlet communicating with the mixing chamber. Gas-liquid two-phase materials are introduced into the mixing chamber through the inlet for mixing. A distribution assembly is provided in the mixing chamber to distribute the materials in the mixing chamber to a first diffusion section corresponding to the center of the mixing chamber and a second diffusion section surrounding the first diffusion section, so as to make the materials more uniformly dispersed. When the premixed inlet diffuser is provided at the inlet of the fixed-bed hydrogenation reactor, the gas-liquid two-phase materials can be uniformly dispersed after mixing when passing through the premixed diffuser provided in the fixed-bed hydrogenation reactor, so that the mixed materials can enter the bed more uniformly, thereby improving the reaction efficiency of the fixed-bed hydrogenation reactor.

[0004] CN206152774U relates to a fixed-bed hydrogenation reactor with a high-efficiency heat exchange layer. It includes a reactor shell, a liquid feed pipe, a gas-liquid distributor, a catalyst layer, and a heat exchange layer. The catalyst layer can be in one or more sections. When multiple catalyst layers are used, a liquid collection plate and a gas-liquid redistributor are provided between each section. The heat exchange layer is located downstream of each catalyst layer according to temperature control requirements. If it is located below the catalyst in the middle section, it is constructed using ceramic balls or catalyst-covered coils; if located at the lower head, the head contains heat exchange coils, which are then filled with ceramic balls. A wire mesh is laid on the ceramic balls, and the catalyst is loaded onto the wire mesh.

[0005] As raw materials become increasingly heavy and of lower quality, high concentrations of impurities such as residual carbon, metals, colloids, and asphaltene in the raw materials are easily adsorbed, deposited, and coked in the first catalyst bed at the top of the reactor, causing the pressure drop (ΔP) in the first bed of the reactor to rise rapidly.

[0006] When the pressure drop of the first bed reaches the design limit, the unit must be reduced or even shut down to replace or regenerate the top catalyst. This not only shortens the effective operating cycle and reduces the operating rate, but also causes significant economic losses. This is because often only a small amount of catalyst at the top is deactivated due to physical blockage, while the catalyst in the middle and lower parts remains active. However, due to the pressure drop problem, the entire line is forced to shut down for catalyst replacement, resulting in low catalyst utilization.

[0007] Existing technologies typically employ measures such as optimizing catalyst shape, adding graded protective agents, or backwashing to slow down the pressure drop increase. However, these methods cannot fundamentally solve the pressure drop bottleneck caused by the continuous accumulation of impurities and the resulting unplanned shutdowns. Therefore, there is an urgent need for a process method that can proactively manage the catalyst deactivation process and significantly extend the reactor's operating cycle. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a process method that can actively manage the catalyst bed and effectively extend the single operation cycle of a fixed bed reactor.

[0009] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a catalyst management and operation cycle extension process for a fixed-bed reactor based on multi-side feed switching, applied to a fixed-bed reactor having at least two catalyst beds and at least two feed inlets, characterized by including the following steps: S1: In the reactor, the catalyst is loaded from top to bottom. The reactants enter from the first feed inlet and react sequentially through all the catalyst beds. S2: Real-time monitoring of the pressure drop of the upstream catalyst bed or bed group; S3: When the monitored pressure drop reaches the first preset threshold, the feed inlet of the reaction raw material is switched from the first feed inlet to the third feed inlet; the third feed inlet is located downstream of the upstream catalyst bed or bed group, so that after the switch, the reaction raw material bypasses the blocked upstream bed or bed group and directly enters the downstream bed to continue the reaction. S4: Continue to monitor the pressure drop of the downstream catalyst bed, and selectively switch the feed inlet to a more downstream feed inlet based on the changes in pressure drop; S5: When the downstream bed pressure drop corresponding to the last feed port reaches the set upper limit, execute the planned shutdown and replace or regenerate the deactivated catalyst bed.

[0010] A further preferred embodiment of the present invention is as follows: in step S1, catalysts with different functions are loaded in different bed layers, including a protective agent and a main reaction catalyst from top to bottom.

[0011] A further preferred embodiment of the present invention is as follows: the first feed inlet is located at the top of the uppermost catalyst bed, and the second feed inlet is located between the uppermost catalyst bed and the adjacent downstream catalyst bed.

[0012] A further preferred embodiment of the present invention is as follows: In step S3, while switching the feed inlet, the operating conditions of the reactor are adjusted, including one or more of temperature, pressure and hydrogen-to-oil ratio.

[0013] A further preferred embodiment of the present invention is that the process further includes replacing or regenerating only the deactivated catalyst bed located upstream of the currently used feed inlet after a shutdown, while retaining the downstream catalyst with remaining activity.

[0014] A further preferred embodiment of the present invention is: a demetallization aid layer is disposed above the upstream catalyst, and the demetallization aid is prepared by: K1: According to the mass fraction, add 100-130 parts of kaolin-supported nickel oxide precursor, 2.0-5.0 parts of γ-methacryloyloxypropyltrimethoxysilane (KH570), and 700-1000 parts of toluene to the reactor, stir and disperse evenly, and heat to 70-90℃ to react for 1-3 hours. K2: Add 1.0 to 5.0 parts of N-octadecyl-1-octadecylamine and 0.5 to 2.0 parts of triethylamine, and keep the reaction at a constant temperature for 1 to 3 hours; after the reaction is complete, filter, wash with ethanol, and dry at 92-105℃ for 4 to 6 hours to obtain the surface-modified metallizing agent.

[0015] Mechanism of metallization aid reaction: This method focuses on silane coupling, long-chain amine surface modification, and interfacial bonding. KH570 undergoes a condensation reaction with hydroxyl groups on the particle surface to form stable covalent bonds. N-octadecyl-1-octadecylamine and triethylamine work synergistically to construct a uniform organic coating layer on the particle surface, effectively reducing interfacial energy, inhibiting particle agglomeration and sintering, and maintaining the active components in a highly dispersed state. Effects of metal removal aid technology: 1) It can form a dense and firmly bonded organic coating layer on the particle surface, significantly reducing the interfacial energy and electrostatic adsorption of particles, inhibiting powder agglomeration, accumulation and sintering from the source, and improving the uniformity and stability of the system.

[0016] 2) It anchors and isolates the active components, effectively inhibiting the migration, aggregation and crystal growth of the active phase during operation, maintaining a highly dispersed state of active sites, and extending the effective service life of the additive.

[0017] 3) Optimize particle surface wettability and interfacial compatibility, improve bed flow performance, reduce the risk of local blockage and pressure drop fluctuations, and enhance the stability and long-term reliability of the unit.

[0018] This invention introduces a dynamic feed inlet switching strategy based on bed pressure drop monitoring, building upon the traditional fixed-bed reactor operation process. The core of this process lies in changing the catalyst bed clogging and deactivation process from "all beds simultaneously experiencing impurity impacts" to "experiencing impacts in batches and sequentially" by switching feed inlets, thereby actively managing the catalyst deactivation process. This achieves two major benefits: firstly, it significantly extends the reactor's single-cycle operation, reducing unplanned downtime; secondly, it improves catalyst utilization, changing "full-line replacement" to "partial replacement," saving costs. This process is particularly suitable for processing low-quality feedstocks with high impurity content, enhancing the adaptability and operational economy of the unit. Attached Figure Description

[0019] Figure 1 This is a simplified flowchart of the process of the present invention; Figure 2 This is a schematic diagram comparing the bed pressure drop over time using the process of this invention with that of a traditional process. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] like Figure 1 As shown, a multi-side-feed fixed-bed reactor suitable for this process includes a shell and first, second, third, fourth, and fifth catalyst beds arranged from top to bottom within the shell. A first feed inlet is located at the top of the reactor, a second feed inlet is located between the second and third beds, and a third feed inlet is located between the fourth and fifth beds. Both the second and third feed inlets are equipped with independently controllable valves. Each bed is equipped with a differential pressure monitoring instrument.

[0022] A specific application example of the process of this invention is as follows, taking a hydrorefining reactor with five catalyst beds and two side feed inlets for processing low-quality diesel as an example: 1. Initial stage (0-12 months): The reaction feedstock enters through the first inlet and passes sequentially through the first bed (filled with protective agent), the second bed, and the third bed (filled with main purification catalyst). The system operates stably, and the pressure drop ΔP1 in the first bed slowly increases due to the retention of most impurities.

[0023] 2. First Switchover (12th Month): The pressure drop ΔP1 in the first bed is monitored to reach a preset threshold (e.g., 0.5 MPa). The control system issues a command to close the first feed inlet valve and simultaneously open the second feed inlet valve. The reactants are now fed directly into the third bed from the second feed inlet. At this point, the severely clogged first bed is completely bypassed, and the reaction load is borne by the third and fourth beds. The total pressure drop of the unit immediately decreases significantly, and stable operation is restored.

[0024] 3. Post-switchover operation phase (months 12-20): The system continues to operate in the second feed inlet mode. Impurities begin to accumulate at the top of the third bed, and its pressure drop ΔP2 begins to rise slowly.

[0025] 4. Planned Shutdown and Catalyst Replacement (20 Months and Above): When the pressure drop ΔP3 of the fifth bed approaches the design limit, or when the activity of the fifth bed is insufficient, a planned shutdown will be arranged. After shutdown, only the catalyst in the first bed, the upper part of the third bed, and the upper part of the fifth bed, which have been completely deactivated, will be replaced. The catalyst in the second bed and the lower part of the fourth bed, which maintain relatively good activity, can be retained for continued use.

[0026] Among them, a demetallization aid layer is set above the upstream catalyst, and the preparation method of the demetallization aid is as follows: K1: Add 100 kg of kaolin-supported nickel oxide precursor, 2.0 kg of γ-methacryloyloxypropyltrimethoxysilane (KH570), and 700 kg of toluene to the reactor, stir and disperse evenly, and heat to 70°C to react for 3 hours. K2: Add 1.0 kg N-octadecyl-1-octadecylamine and 0.5 kg triethylamine, and keep the reaction at the temperature for 1 hour; after the reaction is completed, filter, wash with ethanol, and dry at 92℃ for 6 hours to obtain the surface-modified metallizing agent. Example 2

[0027] In this example, the preparation method of the metal removal agent is different from that in Example 1, but the rest is the same as in Example 1.

[0028] The preparation method of the metallization aid in this example is as follows: K1: Add 115 kg of kaolin-supported nickel oxide precursor, 3.5 kg of γ-methacryloyloxypropyltrimethoxysilane (KH570), and 850 kg of toluene to the reactor, stir and disperse evenly, and heat to 80℃ to react for 2 hours. K2: Add 3.0 kg N-octadecyl-1-octadecylamine and 1.2 kg triethylamine, and keep the reaction at a constant temperature for 2 hours. After the reaction is complete, filter, wash with ethanol, and dry at 98°C for 5 hours to obtain the surface-modified metallizing agent. Example 3

[0029] In this example, the preparation method of the metal removal agent is different from that in Example 1, but the rest is the same as in Example 1.

[0030] The preparation method of the metallization aid in this example is as follows: K1: Add 130 kg of kaolin-supported nickel oxide precursor, 5.0 kg of γ-methacryloyloxypropyltrimethoxysilane (KH570) and 1000 kg of toluene to the reactor, stir and disperse evenly, and heat to 90℃ to react for 1 hour; K2: Add 5.0 kg N-octadecyl-1-octadecylamine and 2.0 kg triethylamine, and keep the reaction at a constant temperature for 3 hours. After the reaction is complete, filter, wash with ethanol, and dry at 105℃ for 4 hours to obtain the surface-modified metallizing agent.

[0031] In this surface modification system, KH570 provides interfacial bonding and dispersion, N-octadecyl-1-octadecylamine constructs a long-lasting hydrophobic protective layer, and triethylamine promotes uniform reaction. The three work synergistically to achieve a comprehensive effect of preventing aggregation, stabilizing structure, and maintaining activity, enabling the metallization aid to meet the requirements of high stability and long-term use.

[0032] In contrast, with a traditional single-feed inlet process, the entire plant may need to be shut down and all catalysts replaced after 12 months of operation (i.e., when the first bed becomes clogged). The process of this invention extends the operating cycle from 12 months to 24 months with a single feed inlet switch, reduces catalyst replacement by approximately one-third, and yields significant economic benefits.

[0033] The foregoing has provided a detailed description of a catalyst management and operation cycle extension process for a fixed-bed reactor based on multi-side feed switching, as provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A catalyst management and cycle extension process for a fixed-bed reactor based on multi-side feed switching, applied to a fixed-bed reactor having at least two catalyst beds and at least two feed inlets, characterized in that, Includes the following steps: S1: The reactants enter the reactor through the first feed inlet and react sequentially through all catalyst beds; S2: Real-time monitoring of the pressure drop of the upstream catalyst bed or bed group; S3: When the monitored pressure drop reaches the first preset threshold, the feed inlet of the reaction raw material is switched from the first feed inlet to the second feed inlet; the second feed inlet is located downstream of the upstream catalyst bed or bed group; S4: When the pressure drop of the downstream catalyst bed reaches a new preset threshold after switching to the second feed port, the feed port can be further switched to the third feed port further downstream.

2. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching as described in claim 1, characterized in that: In step S1, catalysts with different functions are loaded into different beds of the reactor.

3. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching as described in claim 1, characterized in that: The second feed inlet is located between the uppermost catalyst bed and the adjacent downstream catalyst bed.

4. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching as described in claim 1, characterized in that: In step S3, the operating conditions of the reactor are adjusted while the feed inlet is being switched.

5. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching according to claim 1, characterized in that: The operating conditions include one or more of the following: reaction temperature, system pressure, and hydrogen-to-oil ratio.

6. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching according to claim 1, characterized in that: The process also includes step S5: when the pressure drop of the downstream bed corresponding to the final feed inlet reaches the set upper limit, a planned shutdown is executed, and only the catalyst bed located upstream of the feed inlet is replaced or regenerated.

7. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching according to claim 1, characterized in that: The fixed-bed reactor is a fixed-bed hydrogenation reactor.

8. The process for catalyst management and extended operating cycle of a fixed-bed reactor based on multi-side feed switching according to claim 1, characterized in that: A demetallization aid layer is disposed above the upstream catalyst. The demetallization aid is prepared by: K1: According to the mass fraction, add 100-130 parts of kaolin-supported nickel oxide precursor, 2.0-5.0 parts of γ-methacryloyloxypropyltrimethoxysilane, and 700-1000 parts of toluene to the reactor, stir and disperse evenly, and heat to 70-90℃ to react for 1-3 hours. K2: Add 1.0 to 5.0 parts of N-octadecyl-1-octadecylamine and 0.5 to 2.0 parts of triethylamine, and keep the reaction at a constant temperature for 1 to 3 hours; after the reaction is complete, filter, wash with ethanol, and dry at 92-105℃ for 4 to 6 hours to obtain the surface-modified metallizing agent.

Images