A molybdate feeding system and method suitable for use in a catalyst preparation unit

Abstract

This invention discloses a molybdenum acid feeding system and method for a catalyst preparation unit. The system includes a feed hopper, a vacuum filter, a liquid ring vacuum pump, a nitrogen purging pipeline, a discharge hopper, and a reaction vessel. All components are connected in a closed loop via four lines. Matching regulating valves are installed on the pipelines. During feeding, the system is first sealed, and a stable negative pressure is established by the liquid ring vacuum pump. The molybdenum acid powder is then drawn into the vacuum filter for retention. Nitrogen gas is then introduced for reverse purging, pushing the material to the discharge hopper, and finally into the reaction vessel to complete the feeding process. This invention achieves fully enclosed, dust-free transport, effectively solving problems such as dust pollution, material loss, pipeline blockage, and equipment damage. It significantly improves feeding accuracy and production efficiency, reduces maintenance costs, and features a simple system structure suitable for large-scale, stable industrial production of catalysts, showing broad prospects for industrial application.

Description

Technical Field

[0001] This invention relates to the field of petrochemical catalyst production technology, specifically to a molybdenum acid feeding system and feeding method for a catalyst preparation unit. Background Technology

[0002] Slurry-bed residue hydrotreating technology, as a groundbreaking innovation in the field of heavy oil processing, has milestone industry value and has become a core process unit for new-generation integrated refining and chemical enterprises to process inferior heavy oil and achieve efficient and clean conversion of petroleum resources. With a heavy oil conversion efficiency exceeding 90%, this technology exhibits strong adaptability and tolerance to extremely low-quality residue oil feedstocks with high sulfur, high metal, and high residual carbon content. It can significantly improve the depth of feedstock processing and the added value of products, helping refining and chemical enterprises effectively reduce the procurement costs of inferior feedstocks, optimize the structure of core products such as gasoline, diesel, and kerosene, and create significant economic benefits and core industrial competitiveness. It is currently one of the mainstream technological directions in the global heavy oil deep processing field.

[0003] As an indispensable core supporting process unit in slurry-bed residue hydrotreating technology, the catalyst preparation unit directly determines whether the main slurry-bed residue hydrotreating unit can achieve long-term, high-load, and stable operation due to the quality, performance stability, and continuous and stable supply capacity of the catalysts produced. It is also a key prerequisite and core guarantee for the entire process to achieve efficient conversion and clean production goals, and has a decisive impact on the operating efficiency and overall benefits of the entire slurry-bed residue hydrotreating system. In the catalyst preparation process for heavy oil deep processing processes such as slurry-bed residue hydrotreating, molybdic acid, as the core solid active precursor powder raw material, needs to be precisely, cleanly, and stably quantitatively added into the reactor to participate in the synthesis reaction.

[0004] Due to the unique process characteristics and reaction mechanism requirements of slurry-bed residue hydrotreating catalysts, some key raw materials (such as molybdic acid) need to be precisely and quantitatively added in high-purity solid powder form. This addition process is constrained by the characteristics of the raw materials themselves and the stringent process requirements of subsequent catalyst preparation and hydrogenation reactions, placing extremely stringent demands on the rationality of the on-site addition system's process design, the cleanliness of the operating environment, the stability of material transport, and the accuracy of quantitative addition. In the current field of catalyst preparation technology, existing technologies for adding solid powder raw materials to such catalysts generally employ traditional methods such as manual feeding or open conveying. While these methods offer advantages such as low initial investment costs, simple structure, and convenient commissioning, they present several core technical challenges that urgently need to be addressed in large-scale continuous industrial production scenarios for catalyst preparation. These challenges are as follows: 1) During manual handling and open-style filling, molybdenum acid powder is prone to dust generation, causing not only raw material loss but also pollution of the operating environment and harming the health of operators; 2) Manual operation is inefficient and difficult to accurately control the filling amount, leading to deviations in the catalyst formulation ratio, affecting catalyst activity and hydrogenation reaction efficiency; 3) The lack of airtightness in the transportation process allows molybdenum acid to easily absorb moisture from the air, causing it to agglomerate or become mixed with impurities, reducing the purity of the raw material; 4) Simple mechanical transportation is prone to pipeline blockage due to the poor flowability of molybdenum acid powder, requiring frequent shutdowns for cleaning, affecting the continuous operation of the unit; 5) Traditional processes lack targeted residue removal designs, causing raw materials to adhere to the inner walls of the conveying equipment, further exacerbating metering deviations and equipment maintenance costs. These problems severely restrict the stability, safety, and production efficiency of catalyst preparation, becoming a technical bottleneck that urgently needs to be addressed in the industry. The inability to adapt to the demands of large-scale continuous production for continuous, stable, and precise quantitative filling of raw materials easily leads to supply disruptions or imbalances in the ratio of raw materials in the catalyst preparation unit, thereby affecting the long-term stable operation of the slurry bed residue oil hydrogenation main unit.

[0005] Currently, there is no complete set of molybdic acid feeding systems that can achieve fully enclosed, negative pressure conveying combined with precise inert gas purging, low residue, and high precision. The industry has an urgent need for technologies that can solve the problems of closed and dust-free powder conveying, stable and accurate filling, and long-term equipment protection. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of dust pollution, pipeline blockage, material residue, and equipment damage in the existing molybdenum acid powder feeding process, and to provide a closed, clean, and high-precision molybdenum acid feeding system and method for catalyst preparation units. By combining negative pressure suction with nitrogen closed-loop purging, a dust-free conveying and precise feeding process is achieved throughout, reducing raw material loss and ensuring operational safety and personnel health; improving material purity and metering stability, extending the continuous operation cycle of equipment; simplifying operation, reducing labor intensity, and meeting the high-efficiency, environmentally friendly, and long-cycle operation requirements of continuous industrial catalyst production.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: The present invention provides a molybdenum acid feeding system for a catalyst preparation unit, comprising a feed hopper, a vacuum filter, a liquid ring vacuum pump, a nitrogen purging pipeline, a discharge hopper, and a reaction vessel; The feed hopper is connected to the vacuum filter via line 1. The vacuum filter is connected to the liquid ring vacuum pump via line 2. The vacuum filter is connected to the discharge hopper via line 3. The discharge hopper is connected to the reactor via line 4. The nitrogen purging pipeline, line 1, line 2, line 3, and line 4 are interconnected. Regulating valve assemblies are installed on both the nitrogen purging pipeline and line 2.

[0008] Preferably, the liquid ring vacuum pump can evacuate the first line, the second line, and the vacuum filter to a negative pressure of -0.05 to -0.08 MPa.

[0009] Preferably, the nitrogen pressure introduced into the nitrogen purging pipeline is controlled at 0.2MPa to 0.4MPa.

[0010] Preferably, the vacuum filter has a removable filter layer that intercepts molybdenum acid powder and prevents the powder from entering the liquid ring vacuum pump.

[0011] Preferably, the feed hopper is equipped with a sealing cover and a dustproof sealing layer, and a liquid level monitor is installed on the feed hopper.

[0012] Preferably, the regulating valve assembly on the nitrogen purging pipeline includes a regulating valve, a ball valve, a check valve, and a shut-off valve connected in sequence; the regulating valve assembly on the second line includes a ball valve, a check valve, a regulating valve, and a gate valve connected in sequence; and regulating valves are connected to the first, third, and fourth lines.

[0013] Preferably, the No. 1 line, No. 2 line, No. 3 line, and No. 4 line form a closed pipeline.

[0014] This invention discloses a method for feeding molybdate into a catalyst preparation unit, comprising the following steps: Step 1) Add molybdic acid raw material to the feed hopper and close the sealing cover to ensure the system is airtight; Step 2) Start the liquid ring vacuum pump to draw negative pressure so that the molybdenum acid in the feed hopper is drawn into the vacuum filter through line 1; Step 3) After confirming that the material has been emptied by the feed hopper level monitor, stop the liquid ring vacuum pump and close the vacuum pipeline valve; Step 4) Open the nitrogen purging line and use nitrogen back-purge to send the molybdenum acid in the vacuum filter to the unloading hopper via line 3; Step 5) The molybdenum acid in the feed hopper is fed into the reactor via line 4 to complete the filling.

[0015] Preferably, in step 2), the system negative pressure is maintained at -0.05 to -0.08 MPa.

[0016] Preferably, the nitrogen purging pressure in step 4) is controlled at 0.2 to 0.4 MPa.

[0017] Beneficial Effects: The entire system of this invention adopts a closed pipeline design throughout, combined with negative pressure suction and nitrogen closed-loop transportation, completely eliminating the escape of molybdenum acid powder dust from the source, significantly improving the workshop operating environment, reducing raw material loss, and significantly enhancing environmental protection and operational safety. The vacuum filter has a removable filter layer inside, which can effectively intercept fine molybdenum acid powder, completely preventing powder from entering the liquid ring vacuum pump and causing pump wear, blockage, and jamming, greatly extending the service life of the vacuum pump and reducing equipment maintenance costs and downtime frequency. The nitrogen reverse purging design can completely clean and push the residual molybdenum acid powder adhering to the filter layer and pipeline inner wall to the feeding hopper, with no material residue on the wall, greatly improving the metering accuracy of the dosing, ensuring batch consistency of catalyst formulation and stable product performance. The negative pressure value, nitrogen pressure, and delivery rate can be adjusted to adapt to the process requirements of different batches and different feeding amounts, and the system has strong adaptability. It greatly reduces the intensity of manual operation, simplifies the operation process, and can achieve continuous long-term stable operation, adapting to the needs of large-scale industrial continuous production of catalyst preparation, and has extremely high application value. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Technical solution / principle: This invention provides a molybdenum acid feeding system for a catalyst preparation unit, overcoming the deficiencies of the prior art. The system includes a feed hopper V-1010, a vacuum filter V-1011, a liquid ring vacuum pump P-1010, a nitrogen purging pipeline, a discharge hopper V-1012, and a reactor R-1001. The feed hopper V-1010 is connected to the vacuum filter V-1011 via line one; the vacuum filter V-1011 is connected to the liquid ring vacuum pump P-1010 via line two; the vacuum filter V-1011 is connected to the discharge hopper V-1012 via line three; and the discharge hopper V-1012 is connected to the reactor R-1001 via line four. The nitrogen purging pipeline, line one, line two, line three, and line four are interconnected, and regulating valve assemblies are installed on both the nitrogen purging pipeline and line two.

[0021] The liquid ring vacuum pump P-1010 can evacuate the No. 1 and No. 2 lines, as well as the interior of the vacuum filter V-1011, to a negative pressure of -0.05 to -0.08 MPa, providing stable suction power for the entire powder conveying process. The nitrogen pressure in the nitrogen purging line is controlled between 0.2 MPa and 0.4 MPa, enabling stable pressurized conveying and reverse purging operations. The vacuum filter V-1011 has a built-in removable filter layer (the specific model and specifications of the filter layer are not limited and can be selected according to actual needs). This filter layer is used to intercept molybdenum acid powder throughout the process, preventing it from entering the interior of the downstream liquid ring vacuum pump P-1010, achieving efficient gas-solid separation and protecting the vacuum pump equipment from dust wear and clogging. The V-1010 feeding hopper is equipped with a sealing cover and a dustproof sealing layer, which can ensure that the entire hopper is sealed after feeding, preventing dust from escaping and air impurities from entering. The V-1010 feeding hopper is also equipped with a liquid level monitor, which can accurately monitor the remaining amount of material in the hopper in real time and accurately determine the emptying status.

[0022] The regulating valve assembly on the nitrogen purging pipeline includes a regulating valve, ball valve, check valve, and shut-off valve connected in sequence, which can precisely control the nitrogen pressure and flow rate. The check valve prevents the process gas from flowing back. The regulating valve assembly on line two includes a ball valve, check valve, regulating valve, and gate valve connected in sequence, which can reliably open and close the vacuum passage, accurately regulate the pressure, and reliably shut off the system for maintenance. Regulating valves are connected to lines one, three, and four, which can independently control the material flow and conveying rate of each branch. Lines one, two, three, and four together form a complete closed pipeline, achieving fully sealed and dust-free conveying and isolating the entire process from external atmospheric interference.

[0023] This invention also provides a method for feeding molybdate into a catalyst preparation unit, specifically including the following steps: Step 1) Add molybdic acid raw material to feed hopper V-1010, close the sealing cover, and use the dustproof sealing layer to ensure that the entire conveying system is completely sealed; Step 2) Start the liquid ring vacuum pump P-1010 to draw the system to negative pressure and maintain it at -0.05 to -0.08 MPa. The negative pressure suction force causes the molybdenum acid raw material inside the feed hopper V-1010 to be smoothly drawn into the vacuum filter V-1011 through line 1. Step 3) Observe the material status in real time through the liquid level monitor on the feed hopper V-1010. After confirming that the material inside the feed hopper V-1010 has been completely emptied, stop the liquid ring vacuum pump P-1010, close the vacuum pipeline valve on line 2, and release the negative pressure state of the system. Step 4) Open the nitrogen purging pipeline and stabilize the nitrogen pressure at 0.2-0.4MPa. Use nitrogen to purge the inside of vacuum filter V-1011 in reverse. The molybdenum powder trapped in vacuum filter V-1011 and the residual material attached to the filter layer are purged and transported to the unloading hopper V-1012 for temporary storage via line 3. Step 5) The molybdenum acid powder temporarily stored inside the feeding hopper V-1012 is stably conveyed into the reactor R-1001 via line 4, completing a single dust-free and sealed molybdenum acid filling operation.

[0024] The present invention will be further described in detail below with reference to specific embodiments.

[0025] Example 1: This example provides a molybdic acid feeding system and feeding process for a catalyst preparation unit.

[0026] System components: feed hopper V-1010, vacuum filter V-1011, liquid ring vacuum pump P-1010, nitrogen purging pipeline, discharge hopper V-1012, and reactor R-1001; feed hopper V-1010 is connected to vacuum filter V-1011 via line 1, vacuum filter V-1011 is connected to liquid ring vacuum pump P-1010 via line 2, vacuum filter V-1011 is connected to discharge hopper V-1012 via line 3, and discharge hopper V-1012 is connected to reactor R-1001 via line 4; the nitrogen purging pipeline is connected to all pipelines, and both the nitrogen purging pipeline and line 2 are equipped with regulating valve assemblies. The liquid ring vacuum pump P-1010 can stably maintain the internal negative pressure of the system at -0.06MPa; the nitrogen purging pressure is set to 0.3MPa; the vacuum filter V-1011 is equipped with a removable high-precision filter layer; the feed hopper V-1010 is equipped with a sealing cover, a dustproof sealing layer and a liquid level monitor; the valve groups of each pipeline are arranged as specified in the claims, and the entire pipeline is sealed.

[0027] Feeding Operation Steps: 1) Add 200kg of industrial-grade molybdate powder to the feed hopper V-1010, fasten the sealing cap, tighten the dustproof sealing layer, and confirm that there are no leaks in the entire closed pipeline; 2) Start the liquid ring vacuum pump P-1010 to maintain the negative pressure inside line 1, line 2, and vacuum filter V-1011 at a stable -0.06MPa. Under the action of negative pressure difference, the molybdate powder in the feed hopper V-1010 is smoothly drawn into the vacuum filter V-1011 along line 1. The filter layer completely intercepts the molybdate powder, and clean gas enters the vacuum pump side; 3) Check the liquid level of the feed hopper V-1010. After the monitor confirms that the molybdenum acid material in the silo is completely emptied, it delays for 30 seconds, stops the liquid ring vacuum pump P-1010, and closes the vacuum valve of line 2; 4) Open the nitrogen purging pipeline valve assembly, adjust the nitrogen pressure to stabilize at 0.3MPa, and reverse the nitrogen flow into the vacuum filter V-1011 to purge all the molybdenum acid powder adhering to the surface of the filter layer and the inside of the cavity, so that it all enters the feeding silo V-1012 for temporary storage along line 3; 5) Open the regulating valve of line 4, and the molybdenum acid powder in the feeding silo V-1012 is smoothly fed into the reactor R-1001, completing this complete feeding process.

[0028] The operational results of this embodiment are as follows: there is no dust emission throughout the process, the raw material loss rate is less than 0.8%, the feeding metering error is less than ±0.5%, there are no problems such as pipeline blockage or material clumping due to moisture, and the equipment can run continuously and stably for more than 3 months without stopping for cleaning.

[0029] Example 2: This example is structurally similar to Example 1, with the difference being in the process parameters: the negative pressure of the P-1010 liquid ring vacuum pump control system is -0.05MPa, and the pressure control of the nitrogen purging pipeline is 0.2MPa. This example is suitable for small-batch, high-precision fine material preparation scenarios, further improving the metering accuracy to ±0.3%, with extremely low material residue, making it suitable for small-batch precision synthesis production of high-end catalysts.

[0030] Example 3: This example is basically the same in structure as Example 1, the difference being in the process parameters: the negative pressure of the liquid ring vacuum pump P-1010 control system is -0.08MPa, and the pressure control of the nitrogen purging pipeline is 0.4MPa. This example is suitable for large-volume, high-load, rapid feeding conditions, improving the conveying efficiency by about 15%, and providing a stronger purging and cleaning effect, which can meet the feeding requirements of the unit's full-load continuous production.

[0031] Finally, it should be noted that the present invention is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A molybdenum acid feeding system for catalyst preparation, characterized in that, Includes feed hopper (V-1010), vacuum filter (V-1011), liquid ring vacuum pump (P-1010), nitrogen purging pipeline, discharge hopper (V-1012) and reactor (R-1001); The feed hopper (V-1010) is connected to the vacuum filter (V-1011) via line one. The vacuum filter (V-1011) is connected to the liquid ring vacuum pump (P-1010) via line two. The vacuum filter (V-1011) is connected to the discharge hopper (V-1012) via line three. The discharge hopper (V-1012) is connected to the reactor (R-1001) via line four. The nitrogen purging pipeline, line one, line two, line three, and line four are interconnected, and regulating valve assemblies are provided on both the nitrogen purging pipeline and line two.

2. The molybdenum acid feeding system for a catalyst preparation unit according to claim 1, characterized in that, The liquid ring vacuum pump (P-1010) can pump the No. 1 line, No. 2 line and the vacuum filter (V-1011) to a negative pressure of -0.05 to -0.08 MPa.

3. A molybdenum acid feeding system for a catalyst preparation unit according to claim 1 or 2, characterized in that, The nitrogen pressure introduced into the nitrogen purging pipeline is controlled at 0.2MPa to 0.4MPa.

4. The molybdenum acid feeding system for a catalyst preparation unit according to claim 1, characterized in that, The vacuum filter (V-1011) has a removable filter layer that intercepts molybdate powder and prevents it from entering the liquid ring vacuum pump (P-1010).

5. The molybdenum acid feeding system for a catalyst preparation unit according to claim 1, characterized in that, The feed hopper (V-1010) is equipped with a sealing cover and a dustproof sealing layer, and a liquid level monitor is installed on the feed hopper (V-1010).

6. The molybdenum acid feeding system for a catalyst preparation unit according to claim 3, characterized in that, The regulating valve assembly on the nitrogen purging pipeline includes a regulating valve, a ball valve, a check valve, and a shut-off valve connected in sequence; the regulating valve assembly on line two includes a ball valve, a check valve, a regulating valve, and a gate valve connected in sequence; regulating valves are connected to lines one, three, and four.

7. The molybdenum acid feeding system for a catalyst preparation unit according to claim 1, characterized in that, The No. 1, No. 2, No. 3, and No. 4 lines form a closed pipeline.

8. A method for feeding molybdate into a catalyst preparation unit, using the system described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1) Add molybdic acid raw material to the feed hopper (V-1010), and close the sealing cover to ensure the system is airtight; Step 2) Start the liquid ring vacuum pump (P-1010) to draw negative pressure so that the molybdic acid in the feed hopper (V-1010) is drawn into the vacuum filter (V-1011) through line 1. Step 3) After confirming that the material has been emptied by the liquid level monitor of the feed hopper (V-1010), stop the liquid ring vacuum pump (P-1010) and close the vacuum pipeline valve; Step 4) Open the nitrogen purging line and use nitrogen back-purge to send the molybdenum acid in the vacuum filter (V-1011) to the unloading hopper (V-1012) via line 3. Step 5) The molybdic acid in the feed hopper (V-1012) is fed into the reactor (R-1001) via line 4 to complete the filling.

9. The method for feeding molybdenum acid into the catalyst preparation unit according to claim 8, characterized in that, In step 2), the system negative pressure is maintained at -0.05 to -0.08 MPa.

10. The method for feeding molybdenum acid into the catalyst preparation unit according to claim 8, characterized in that, In step 4), the nitrogen purging pressure is controlled at 0.2–0.4 MPa.

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