A fractionating column bottom pump for naphtha hydrogenation unit

Abstract

The utility model relates to petroleum chemical process pump technical field, concretely relates to use brain oil hydrogenation device reformation fractionating column bottom pump, including pump body, pump cover, impeller, casing mouth ring, impeller mouth ring, shaft, bearing body, mechanical seal, coupling and so on spare part, through redesigning impeller hydraulic model, reduced pump flow under the premise of guaranteeing pump lift unchangeable, optimized pump body structure and spare part cooperation gap simultaneously, effectively promoted the operation efficiency of pump, reduced the energy consumption of naphtha hydrogenation device, fully utilized the components such as original pump casing, motor, base in the process of reformation, only replaced a small amount of spare parts such as impeller, impeller mouth ring, casing mouth ring and impeller nut, do not need to add a large number of new equipment, greatly reduced the reformation investment.

Description

Technical Field

[0001] This utility model relates to the field of petrochemical process pump technology, specifically to a fractionation tower bottom pump for a naphtha hydrogenation unit. Background Technology

[0002] In recent years, the country has placed increasingly higher demands on energy conservation and emission reduction, making the application and promotion of energy-saving technologies and equipment all the more important. This paper analyzes the feasibility of energy-saving retrofitting of the bottom pump of the fractionation tower in a naphtha hydrotreating unit. Through hydraulic design, structural analysis, and calculation of matching dimensions, a practical retrofitting plan was formulated while making full use of the original shell. The energy-saving retrofitting of the bottom pump was implemented, and the actual operating effect of the retrofitted pump is excellent. It not only fully meets the process requirements but also saves money, accumulating experience for energy-saving retrofitting projects.

[0003] Based on the process parameters required for the modified unit, and through water calculations and analysis, a modification plan was developed that only required replacing the impeller, impeller wear ring, casing wear ring, and impeller nut, while making full use of the original pump casing, motor, and base components. The modification work was then carried out. The modified fractionation tower bottom pump is operating well, not only meeting process requirements but also saving energy consumption in the unit.

[0004] Therefore, we propose a bottom pump for a naphtha hydrotreating unit. Utility Model Content

[0005] The main objective of this invention is to provide a bottom pump for a fractionation tower in a naphtha hydrogenation unit, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A fractionation tower bottom pump for a naphtha hydrotreating unit includes core components such as a pump body, pump cover, impeller, casing ring, impeller ring, shaft, bearing housing, mechanical seal, and coupling. The overall structure adopts a BB2 design, namely a horizontal, double-suction, radially split, two-stage centrifugal structure. Specific structural features are as follows:

[0008] Pump body structure: The pump body is radially split and centerline supported, with a top suction port and a top discharge port cast on it for easy fluid intake and discharge. Simultaneously, the pump body employs a double-volute structure, which effectively balances radial forces, reduces pump vibration during operation, and improves equipment operational stability. Furthermore, the pump body volute has pre-drilled holes for venting and draining fluid; when users need to perform venting or draining operations, holes can be opened at the holes to meet actual operational needs.

[0009] Pump cover structure: The pump cover is assembled on both sides of the pump body. The structures of the left and right pump covers are different, and both can be fitted with mechanical seals to achieve a good sealing effect and prevent fluid leakage. An optional water-cooling jacket is cast on the outside of the shaft seal cavity. When the conveying medium is water and the temperature exceeds 66°C, or when the conveying medium is a hydrocarbon and the temperature exceeds 150°C, the water-cooling jacket can be installed to cool the shaft seal cavity through water cooling, ensuring the normal operation of the mechanical seal and extending its service life.

[0010] Impeller and shaft connection structure: The impeller is connected to the shaft via a key to ensure stable power transmission. Simultaneously, the impeller is secured with an impeller nut, which employs a self-tightening thread structure. During pump operation, the tightening force of the nut continuously increases with the rotation of the impeller, effectively preventing the nut from loosening. Furthermore, small hexagonal screws are used to position the impeller nut, further preventing loosening or vibration of the impeller during high-speed operation, ensuring the stability and reliability of the impeller-shaft connection.

[0011] Impeller ring structure: Replaceable impeller rings are provided on both sides of the impeller, and corresponding housing rings are provided on the casing. Both the housing rings and impeller rings are replaceable universal parts, facilitating individual replacement when the rings are worn, thus reducing equipment maintenance costs. Specifically, the impeller ring at the coupling end is larger than the one at the other end. This design allows the pump to generate a slight axial force during operation, ensuring the pump always operates under tension, balancing some of the axial force, and meeting the special requirements of equipment installation and operation.

[0012] Bearing housing structure: The bearing housing is fixed to the bracket with screws and uses a stop-lock positioning method to ensure the accuracy and stability of the bearing housing installation position. In terms of bearing configuration, a set of radial ball bearings is installed near the coupling end, mainly to bear radial forces; the other end is equipped with a set of back-to-back thrust ball bearings, mainly to bear axial forces. This bearing configuration effectively balances the radial and axial forces generated during pump operation, improving equipment operational stability. Each bearing set is equipped with an oil slinger ring for lubrication via oil splashing, ensuring normal bearing operation. Furthermore, the bearing housing is fitted with axial heat sinks, allowing for different cooling methods depending on the actual operating temperature. Air cooling can be used when the temperature is below 120℃; fan cooling can be used when the temperature is between 120-260℃; and water cooling can be used when the temperature is between 260-450℃, ensuring the bearing operates in a suitable temperature environment and extending its service life.

[0013] When retrofitting an existing fractionation tower bottom pump, based on the aforementioned pump structure, and by fully utilizing the original pump casing, motor, and base components, the retrofit can be achieved by simply replacing parts such as the impeller, impeller inlet ring, casing inlet ring, and impeller nut. The impeller requires redesign. The final dimensions are determined by calculating the pump specific speed, impeller inlet diameter Dj, impeller outlet diameter D2, and impeller outlet width b2, combined with equipment performance and structural requirements. A new impeller hydraulic model is then developed to reduce pump flow while maintaining the same pump head, while ensuring the basic performance of the retrofitted pump meets system requirements. Furthermore, the fit dimensions of the impeller inlet ring and casing inlet ring need to be modified to ensure a reasonable clearance and further optimize equipment performance.

[0014] The beneficial effects of this utility model are as follows: By redesigning the impeller hydraulic model, this utility model reduces the pump flow rate while maintaining the same pump head. Simultaneously, it optimizes the pump body structure and component clearances, effectively improving pump operating efficiency and reducing energy consumption in the naphtha hydrogenation unit. During the retrofit, the original pump casing, motor, base, and other components are fully utilized, requiring only the replacement of a small number of parts such as the impeller, impeller wear ring, casing wear ring, and impeller nut. This eliminates the need for extensive new equipment additions, significantly reducing retrofit investment and saving companies on equipment construction and retrofit costs. It is an important way to save investment in the retrofitting of fractionation tower bottom pumps. The use of a self-tightening impeller nut with small internal hexagonal screws for positioning effectively avoids… This design eliminates impeller loosening and vibration during high-speed operation. The double-vortex structure balances radial forces, while the slightly axial force generated by the different-sized impeller rings at the coupling end and the other end keeps the pump in a tension state. Combined with a reasonable bearing configuration and cooling method, this significantly improves the pump's operational stability and reliability, extends equipment lifespan, and reduces maintenance frequency and costs. This fractionation tower bottom pump is not only suitable for naphtha hydrogenation units but can also be used in petroleum refining, petrochemical, and chemical industries to transport petroleum and its products without solid particles. Furthermore, it can select different cooling methods based on the temperature of the transported medium, adapting to various operating conditions and demonstrating strong adaptability and a wide range of applications. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0017] In the diagram: 1. Pump cover; 2. Pump body; 3. Impeller nut; 4. Impeller; 5. Casing ring; 6. Impeller ring; 7. Bearing; 8. Mechanical seal; 9. Shaft. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0019] As one embodiment of this utility model, such as Figure 1 As shown, the present invention discloses a bottom pump for a fractionation tower in a naphtha hydrotreating unit, comprising a pump body 2, a pump cover 1, an impeller 4, a housing ring 5, an impeller ring 6, a shaft 9, a bearing housing, a mechanical seal 8, and a coupling. The pump body 2 is radially split and centerline supported, with a top suction port and a top discharge port cast on it. The pump body 2 employs a double-volute structure to balance radial forces, and a vent is pre-installed on the volute of the pump body 2 for venting and draining liquid. The pump cover 1 is mounted on both sides of the pump body 2, with different structures on the left and right sides and capable of being fitted with the mechanical seal 8. An optional water-cooling jacket is cast on the outer side of the shaft seal cavity. The impeller 4 is driven by the shaft 9 via a key. The impeller 4 is connected and secured by an impeller nut 3, which has a self-tightening thread and is positioned with a small hexagonal screw. Replaceable impeller rings 6 are provided on both sides of the impeller 4, with the impeller ring 6 at the coupling end being larger than that at the other end, causing the pump to generate a slight axial force and operate under tension. The bearing housing is fixed to the bracket with screws and positioned using a stop. A set of radial ball bearings is mounted at the coupling end, and a set of thrust ball bearings mounted back-to-back at the other end. Each bearing set is equipped with an oil slinger ring for splash lubrication. Axial heat sinks are cast on the bearing body, and air cooling, fan cooling, or water cooling methods can be selected.

[0020] This utility model also includes that the housing mouth ring 5 and the impeller mouth ring 6 are replaceable universal rings.

[0021] This utility model also includes a self-tightening thread structure for the impeller nut 3, which increases the tightening force of the nut as the impeller 4 rotates during pump operation. Combined with the small internal hex screw for positioning, it prevents the impeller 4 from loosening or vibrating during high-speed operation.

[0022] When using this utility model, first place the pump body 2 in the designated installation position to ensure that the radial split surface of the pump body 2 is flat and the centerline support structure is stable.

[0023] Pump covers 1 are installed on both sides of the pump body 2. Due to the different structures of the left and right pump covers 1, care must be taken to distinguish their installation positions. After assembly, ensure that the pump cover 1 and the pump body 2 are well sealed and there is no risk of leakage. At the same time, depending on the temperature of the conveyed medium, decide whether to install a water-cooling jacket on the outside of the shaft seal cavity. If the conveyed medium is water and the temperature exceeds 66°C, or is a hydrocarbon and the temperature exceeds 150°C, then a water-cooling jacket should be installed.

[0024] Connect impeller 4 to shaft 9 via a key, ensuring a tight fit between the key, shaft 9, and the keyway of impeller 4 for reliable transmission. Then, tighten impeller 4 with impeller nut 3. The self-tightening thread of impeller nut 3 must be properly engaged with the thread of shaft 9. After tightening, use a small hexagonal screw to position impeller nut 3 to prevent it from loosening.

[0025] Install impeller wear rings 6 on both sides of the impeller 4. Note that the impeller wear ring 6 at the coupling end is larger than the impeller wear ring 6 at the other end. Ensure a tight fit between the impeller wear ring 6 and the impeller 4 during installation. At the same time, install the casing wear ring 5 at the corresponding position on the pump body 2, ensuring that the gap between the casing wear ring 5 and the impeller wear ring 6 meets the design requirements.

[0026] Secure the bearing housing to the bracket with screws, using a stop to ensure accurate positioning. Install a set of radial ball bearings inside the bearing housing near the coupling end, and install a set of thrust ball bearings back-to-back at the other end. Each bearing set is equipped with an oil slinger ring for splash lubrication. Select a suitable cooling method based on actual operating temperature requirements: air cooling for temperatures below 120℃; fan cooling for temperatures between 120-260℃; and water cooling for temperatures between 260-450℃.

[0027] Finally, assemble the mechanical seal 8 and coupling. After assembly, inspect the entire equipment to ensure that all parts are installed in place, reliably connected, and free from looseness or jamming.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The descriptions of the above embodiments and specifications are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by this utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A bottom pump for a fractionation tower in a naphtha hydrotreating unit, characterized in that, The pump body (2) includes a pump cover (1), an impeller (4), a casing ring (5), an impeller ring (6), a shaft (9), a bearing housing, a mechanical seal (8), and a coupling. The pump body (2) is a radially split and center-line supported structure. The pump body (2) is cast with a top suction port and a top discharge port. The pump body (2) adopts a double-volute structure to balance the radial force. The volute of the pump body (2) is reserved with a vent for venting and discharging liquid. The pump cover (1) is assembled on both sides of the pump body (2). The left and right pump covers (1) have different structures and can be equipped with a mechanical seal (8). An optional water-cooling jacket is cast on the outside of the shaft seal cavity. The impeller (4) is connected to the shaft (9) by a key. The impeller is fastened by the impeller nut (3), which has a self-tightening thread and is positioned by a small internal hex screw. The impeller (4) is provided with replaceable impeller mouth rings (6) on both sides, and the impeller mouth ring (6) at the coupling end is larger than the impeller mouth ring (6) at the other end, so that the pump generates a slight axial force and works in a tensile state. The bearing body is fixed to the bracket by screws and is positioned by a stop. A set of radial ball bearings is installed at the coupling end, and a set of thrust ball bearings installed back to back are installed at the other end. Each set of bearings is equipped with an oil slinger ring for splash lubrication. The bearing body is cast with axial heat sinks and can be cooled by air, fan or water.

2. The fractionation tower bottom pump for a naphtha hydrotreating unit according to claim 1, characterized in that, The housing mouth ring (5) and the impeller mouth ring (6) are replaceable universal rings.

3. The fractionation tower bottom pump for a naphtha hydrotreating unit according to claim 1, characterized in that, The self-tightening thread structure of the impeller nut (3) increases the tightening force of the nut as the impeller (4) rotates during pump operation. It is used in conjunction with the small internal hexagonal screw for positioning to prevent the impeller (4) from loosening or vibrating during high-speed operation.

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