Mechanical seal self-flushing and cooling structure of multi-stage centrifugal pump

Abstract

The utility model discloses a multi-stage centrifugal pump mechanical seal self-flushing and cooling structure which comprises a pump machine shell, a bearing bracket, a pump shaft, a mechanical seal, a water inlet overflowing section and a first-stage impeller. The mechanical seal, the water inlet overflowing section and the first-stage impeller are all arranged in an assembly space formed by the pump shell and the bearing bracket, and the mechanical seal and the first-stage impeller are arranged on the pump shaft in a sleeving manner and form a combined overflowing channel with the water inlet overflowing section; a water inlet leading-in channel corresponding to water outlet at the upper end of the first-stage impeller is arranged above the water inlet overflowing section, a flow guide channel corresponding to the water inlet leading-in channel is arranged at the upper end of the bearing bracket, a flushing pipe connected with the flow guide channel is arranged at the water outlet end of the flow guide channel, one end of the flushing pipe is communicated with the water outlet end of the flow guide channel, and the other end of the flushing pipe is communicated with the water outlet end of the first-stage impeller. And the other end penetrates through the bearing bracket and then extends to be communicated with the water inlet of the mechanical seal. And after the flow guide channel is arranged on the bearing bracket, the machining is more convenient, and the machining cost is lower.

Description

Technical Field

[0001] The utility model relates to the field of centrifugal pumps, in particular to a self-flushing and cooling structure for the mechanical seal of a multistage centrifugal pump. Background Art

[0002] Mechanical seal (referred to as "mechanical seal" for short) is one of the key components of pump equipment, and is often applied to the transportation environment with high rotational speed, high pressure, unstable working conditions and complex multiphase (such as solid-liquid two-phase). The formation and maintenance of an extremely thin liquid film between the dynamic and static ring end faces of the mechanical seal is the key to the long-term stable operation of the sealing system. However, during the operation of the mechanical seal for pumps, affected by comprehensive factors such as frequency-changing working conditions, medium conditions, and end face running-in, the end face of the mechanical seal is prone to overheating and deformation, and solid particles, impurities, pollutants, etc. inside or outside the pump are very likely to enter the end face gap of the mechanical seal, aggravating end face wear, and at the same time depositing on springs or auxiliary sealing rings, etc., resulting in the failure of the mechanical seal. Therefore, setting up an effective flushing system for the mechanical seal of pumps is very important for ensuring the stable operation of the mechanical seal and the entire pump.

[0003] As Figure 1 shown, the existing self-flushing water intake for the mechanical seal of a multistage centrifugal pump is to set a through hole at the first-stage impeller in the core of the housing, introduce water into the water inlet flow passage section on one side and the outer housing in sequence, and then pass the water into the mechanical seal through a water guide pipe to communicate with the flushing water inlet of the mechanical seal for self-flushing and cooling of the mechanical seal. The above flushing pipeline system needs to drill holes in the outer housing, and there are the following problems: 1. The outer housing is large in volume and heavy in weight, and the processing cost of drilling for liquid extraction on the outer housing is too high, and the processing of this hole position has become a difficulty due to the requirements for the docking angle of the hole position, invisibly increasing the risk of errors; 2. The orientation of the drilled hole is located at the pump inlet, restricted by the position of the lifting lug of the support plate, and there are limitations in the selection of the hole position orientation; 3. The hole position is located at the welded joint (weld position) of the inlet flange, and the welding forming effect will be indirectly affected when drilling through the weld; 4. The opening position is located at the edge of the end of the outer housing. To reserve space for opening the hole, the overall length of the outer housing needs to be increased, resulting in an increase in the length of the entire pump. And the length of the pump also determines its stability. The shorter the pump, the better the stability. Based on this, the applicant wants to improve the flushing pipeline system to reduce the processing difficulty and cost, and will not affect the stability of the pump unit. Summary of the Invention

[0004] Aiming at the above deficiencies existing in the prior art, the purpose of the utility model is to provide a self-flushing and cooling structure for the mechanical seal of a multistage centrifugal pump, which solves the problems that the existing flushing pipeline system for the mechanical seal of a centrifugal pump is inconvenient to process, has a high processing cost, and the set pipeline will affect the stability of the pump unit.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] A self-flushing and cooling structure for the mechanical seal of a multi-stage centrifugal pump, including a pump housing, a bearing bracket, a pump shaft, a mechanical seal, an inlet flow passage section, and a first-stage impeller. The bearing bracket is fixedly installed on one side of the pump housing. The mechanical seal, the inlet flow passage section, and the first-stage impeller are all placed in the assembly space formed by the pump housing and the bearing bracket. The mechanical seal and the first-stage impeller are sleeved on the pump shaft to form a combined flow passage with the inlet flow passage section. An inlet introduction passage corresponding to the water outlet at the upper end of the first-stage impeller is provided above the inlet flow passage section. A diversion passage corresponding to the inlet introduction passage is provided at the upper end of the bearing bracket. A flushing pipe is provided at the water outlet end of the diversion passage. One end of the flushing pipe is connected to the water outlet end of the diversion passage, and the other end penetrates the bearing bracket and extends into and is connected to the water inlet of the mechanical seal. In this way, when the impeller starts to absorb water, the water flows through the chamber at the upper end of the impeller, enters the inlet introduction passage, then enters the diversion passage, and finally is introduced into the mechanical seal through the flushing pipe for self-cleaning of the mechanical seal. The water inlet of the inlet flow passage section corresponds to the upper end of the first-stage impeller. Compared with the position of the traditional guide vane, the diversion chamber of this water inlet is larger, and it is more convenient to set the inlet introduction passage. The inlet introduction passage is provided on the bearing bracket. Since the overall volume of the bearing bracket is small, it is more convenient to process the diversion passage, the processing cost is lower, and after processing, it is fixed to the pump housing by welding, without interfering with other components and without increasing the overall length of the pump housing, effectively ensuring the stability and reliability of the pump. At the same time, the pump housing and the bearing bracket are integrally formed by welding. During processing, one cut can improve the machining accuracy and concentricity of the parts, greatly improving the assembly reliability and the seal integrity reliability.

[0007] Further, the inlet introduction passage includes an inlet introduction cross passage and a first annular cavity. The diversion passage includes a second annular cavity and an inlet outlet passage communicating with the second annular cavity. The inlet introduction cross passage is arranged close to the first-stage impeller. The first annular cavity is arranged on the side close to the bearing bracket and is arranged opposite to the second annular cavity. In this way, the first annular cavity and the second annular cavity provided ensure the stability of the water flow during the water intake process. The first annular cavity and the second annular cavity are arranged correspondingly, and a relatively large annular water flow chamber can be formed between the inlet flow passage section and the bearing bracket, effectively ensuring the stability of the exported water flow.

[0008] Further, the inlet outlet passage is in an L shape and includes a transverse passage communicating with the second annular cavity and a radial passage communicating with the transverse passage. A connecting flange is provided at the top end of the radial passage. A fixed flange plate corresponding to the connecting flange is provided on the flushing pipe. In this way, the transverse passage provided is used to communicate with the second annular cavity to introduce the water in the second annular cavity, and the radial passage provided can export the water in the transverse passage, and finally the water is guided into the mechanical seal through the flushing pipe.

[0009] Further, a perforation for passing a flushing pipe is provided on one side of the diversion channel. In this way, the provided perforation facilitates the installation of the flushing pipe, enabling the flushing pipe to correspond to the water inlet of the mechanical seal.

[0010] Further, a water guiding channel communicating with the second annular cavity is also provided on the bearing bracket. A cooling water pipeline is provided at the water outlet end of the water guiding channel. The water outlet end of the cooling water pipeline extends into the bearing bracket for spraying cooling water on the bearing or the cooler. In this way, the provided water guiding channel can use the water in the second annular cavity as cooling water, which is then led out and directed to the bearing or the cooler through the pipeline to cool the bearing or the cooler, effectively ensuring the diversity of the product and enabling it to adapt to different situations. This setting can make full use of the water at the impeller, and the processing is also relatively convenient, only ensuring that the end is at any annular point of the second annular cavity.

[0011] Further, there is a gap between the water inlet flow passage section and the bearing bracket, and at least one sealing ring is provided for sealing connection between the water inlet flow passage section and the pump housing and between the water inlet flow passage section and the bearing bracket. In this way, after setting a gap between the water inlet flow passage section and the bearing bracket, it is convenient for welding the bearing bracket and the pump housing, and the processing and welding accuracy do not need to be too high. The provided sealing ring can effectively ensure that the water at the first annular cavity and the second annular cavity does not flow out of the housing through the gap, ensuring the sealing performance and reliability of the housing. Description of the Drawings

[0012] Figure 1 It is a schematic cross-sectional structure diagram of the mechanical seal self-flushing and cooling structure of a multi-stage centrifugal pump in the prior art;

[0013] Figure 2 It is a schematic cross-sectional structure diagram of the mechanical seal self-flushing and cooling structure of a multi-stage centrifugal pump in the embodiment;

[0014] Figure 3 It is a schematic installation structure diagram of the flushing pipe in the embodiment. Detailed Embodiment

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. The components of the embodiments of the present utility model described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present utility model provided in the accompanying drawings is not intended to limit the scope of the claimed present utility model, but merely represents selected embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0016] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. This is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present utility model. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance. In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. In the description of the present utility model, it should also be noted that unless otherwise clearly defined and limited, the terms "set", "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0017] Such as Figure 2 , Figure 3As shown in the figure, the self-flushing and cooling structure of the mechanical seal 6 of the multi-stage centrifugal pump provided in this embodiment includes a pump housing 1, a pump shaft 2, a first-stage impeller 3, an inlet flow passage section 4, a bearing bracket 5, and a mechanical seal 6. The bearing bracket 5 is fixedly installed on one side of the pump housing 1 (the bearing bracket 5 is adjacent to the inlet flow passage section 4). The first-stage impeller 3, the inlet flow passage section 4, and the mechanical seal 6 are all placed in the assembly space formed by the pump housing 1 and the bearing bracket 5. The first-stage impeller 3 and the mechanical seal 6 are both sleeved on the pump shaft 2, and the inlet flow passage section 4 is placed between the first-stage impeller and the mechanical seal 6. A combined flow passage is formed among the first-stage impeller 3, the mechanical seal 6, and the inlet flow passage section 4. An inlet introduction passage 41 corresponding to the water outlet at the upper end of the first-stage impeller 3 is provided above the inlet flow passage section 4. A diversion passage 51 corresponding to the inlet introduction passage 41 is provided at the upper end of the bearing bracket 5. A flushing pipe 7 is provided at the water outlet end of the diversion passage 51. One end of the flushing pipe 7 is communicated with the water outlet end of the diversion passage 51, and the other end penetrates through the bearing bracket 5 and then extends into and is communicated with the water inlet of the mechanical seal 6. In this way, when the impeller starts to absorb water, the water flows through the chamber at the upper end of the impeller, enters the inlet introduction passage 41, then enters the diversion passage 51, and finally is introduced into the mechanical seal 6 through the flushing pipe 7 to perform self-cleaning on the mechanical seal 6. The water inlet of the inlet flow passage section 4 corresponds to the upper end of the first-stage impeller 3. Compared with the position of the traditional guide vane, the diversion chamber of this water inlet is larger, and it is more convenient to set the inlet introduction passage 41. The inlet introduction passage 41 is provided on the bearing bracket 5. Since the overall volume of the bearing bracket 5 is small (it is a relatively small part compared with the pump housing), it is more convenient to process the diversion passage, the processing cost is lower, and after processing, it is fixed to the pump housing by welding, will not interfere with other components, and will not increase the overall length of the pump housing 1, effectively ensuring the stability and reliability of the pump.

[0018] Further, the inlet introduction passage 41 includes an inlet introduction horizontal passage 411 and a first annular cavity 412. The diversion passage 51 includes a second annular cavity 511 and an inlet outlet passage 512 communicated with the second annular cavity 511. The inlet introduction horizontal passage 411 is arranged close to the first-stage impeller 3, and the first annular cavity 412 is arranged close to one side of the bearing bracket 5 and is arranged opposite to the second annular cavity 511. In this way, the first annular cavity 412 and the second annular cavity 511 provided ensure the stability of the water flow during the water intake process. The first annular cavity 412 and the second annular cavity 511 are arranged correspondingly, and a relatively large annular water flow chamber can be formed between the inlet flow passage section 4 and the bearing bracket 5, effectively ensuring the stability of the exported water flow.

[0019] Further, the inlet outlet passage 512 is in an L shape and includes a horizontal passage communicated with the second annular cavity 511 and a radial passage communicated with the horizontal passage. A connecting flange is provided at the top of the radial passage, and a fixed flange plate corresponding to the connecting flange is provided on the flushing pipe 7; Figure 2As shown, a part of the radial channel in this embodiment is located in the body of the bearing bracket 5, and the other part is formed by a pipe extending outward. In this way, the transverse channel is used to communicate with the second annular cavity 511 to introduce water into the second annular cavity 511, and the forward channel is used to guide the water out of the transverse channel, and finally guide the water into the mechanical seal 6 through the flushing pipe 7.

[0020] Further, a perforation for inserting a flushing pipe 7 is provided on one side of the diversion channel 51. In this way, the perforation provided can facilitate the installation of the flushing pipe 7, so that the flushing pipe 7 can correspond to the water inlet of the mechanical seal 6.

[0021] Furthermore, a water guide channel connected to the second annular cavity 511 is provided on the bearing bracket 5, and a cooling water pipeline (not shown in the figure) is provided at the water outlet of the water guide channel, and the water outlet of the cooling water pipeline extends into the bearing bracket 5, and is used to spray cooling water on the bearing or cooler. In this way, the water guide channel provided can use the water in the second annular cavity 511 as cooling water, and then guide the bearing or cooler through the pipeline after being discharged, so as to cool the bearing or cooler, effectively ensuring the diversity of the product and making it adaptable to different situations. This setting can make full use of the water at the impeller, and the processing is also relatively convenient, and it only needs to ensure that the end is at any annular point of the second annular cavity 511.

[0022] Furthermore, there is a gap between the water inlet flow section 4 and the bearing bracket 5, and at least one sealing ring is provided between the water inlet flow section 4 and the pump housing 1, and between the water inlet flow section 4 and the bearing bracket 5 for sealing connection. In this way, after the gap is provided between the water inlet flow section 4 and the bearing bracket 5, it is convenient to weld the bearing bracket 5 and the pump housing 1, and the processing and welding precision will not be too high, and the provided sealing ring can effectively ensure that the water in the first annular cavity 412 and the second annular cavity 511 will not flow out of the housing through the gap, thereby ensuring the sealing of the housing.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit the technical solution. Ordinary technicians in this field should understand that those modifications or equivalent replacements of the technical solution of the utility model without departing from the purpose and scope of the technical solution of the utility model should be included in the scope of the claims of the utility model.

Claims

1. A self-flushing and cooling structure for the mechanical seal of a multistage centrifugal pump, comprising a pump housing, a bearing bracket, a pump shaft, a mechanical seal, an inlet flow passage section, and a first-stage impeller. The bearing bracket is fixedly installed on one side of the pump housing. The mechanical seal, the inlet flow passage section, and the first-stage impeller are all placed in the assembly space formed by the pump housing and the bearing bracket. The mechanical seal and the first-stage impeller are sleeved on the pump shaft and form a combined flow passage with the inlet flow passage section. It is characterized in that, An inlet water guiding channel corresponding to the water outlet at the upper end of the first-stage impeller is provided above the inlet water flow passage. A guiding channel corresponding to the inlet water guiding channel is provided at the upper end of the bearing bracket. A flushing pipe connected thereto is provided at the water outlet end of the guiding channel. One end of the flushing pipe is communicated with the water outlet end of the guiding channel, and the other end penetrates through the bearing bracket and then extends into and is communicated with the water inlet of the mechanical seal.

2. The self-flushing and cooling structure of the mechanical seal of the multi-stage centrifugal pump according to claim 1, characterized in that, The inlet water guiding channel includes an inlet water guiding cross bar and a first annular cavity. The guiding channel includes a second annular cavity and an inlet water outlet channel communicated with the second annular cavity. The inlet water guiding cross bar is arranged close to the first-stage impeller. The first annular cavity is arranged on one side close to the bearing bracket and is arranged opposite to the second annular cavity.

3. The self-flushing and cooling structure of the mechanical seal of the multistage centrifugal pump according to claim 2, characterized in that, The inlet water outlet channel is L-shaped and includes a transverse channel communicated with the second annular cavity and a radial channel communicated with the transverse channel. A connecting flange is provided at the top end of the radial channel. A fixed flange corresponding to the connecting flange is provided on the flushing pipe.

4. The self-flushing and cooling structure of the mechanical seal of the multistage centrifugal pump according to claim 2 or 3, characterized in that, A perforation for passing through the flushing pipe is provided on one side of the guiding channel.

5. The self-flushing and cooling structure of the mechanical seal of the multi-stage centrifugal pump according to claim 4, characterized in that, A water guiding channel communicated with the second annular cavity is further provided on the bearing bracket. A cooling water pipeline is provided at the water outlet end of the water guiding channel. The water outlet end of the cooling water pipeline extends into the bearing bracket and is used for spraying cooling water on the bearing or the cooler.

6. The self-flushing and cooling structure of the mechanical seal of the multi-stage centrifugal pump according to claim 1 or 2 or 3 or 5, characterized in that, A gap exists between the inlet water flow passage and the bearing bracket. At least one sealing ring is provided between the inlet water flow passage and the pump housing and between the inlet water flow passage and the bearing bracket for sealed connection.

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