Pump shaft seal combined structure

Abstract

The utility model discloses a pump shaft seal combined structure, which adopts a mechanical seal assembly and a packing seal assembly, the mechanical seal assembly is arranged at one end of a main shaft and is used for mechanically sealing one end of the main shaft; the packing sealing assembly is arranged at the other end of the main shaft and used for conducting packing sealing on the other end of the main shaft; the packing sealing assembly comprises a packing box, the packing box sleeves the main shaft, and a packing cavity is formed in the position, close to the main shaft, of the packing box. According to the utility model, the original double-end-face mechanical seal is changed into the single-end-face mechanical seal, and the single-end-face mechanical seal is made of common materials, so that the improvement cost is low; the stuffing box is arranged in the stuffing box and is used for keeping the muddy stuffing in a correct shape, so that the muddy stuffing is not plastically deformed during operation, and the sealing effect is good; the holes are formed in the stuffing box and are opposite to the holes in the stuffing box body, the muddy stuffing is injected into the stuffing box through the holes, and the stuffing box is convenient to use.

Description

Technical Field

[0001] The utility model relates to the technical field of mechanical seals, and in particular discloses a pump shaft seal assembly structure. Background Art

[0002] In the chemical industry, pumps are often used to transport aqueous solutions containing phosphoric acid, hydrofluoric acid, and a large amount of chloride ions. The most typical examples are phosphoric acid circulating water and fluorine absorption systems in the phosphoric acid industry.

[0003] The temperature of phosphoric acid circulating water is 35-50℃, and the main corrosive elements are: H2SiF6: 0.2%-3%, P2O5: 0.2%-2%. The spray water temperature in the trace HF fluorine absorption process is 50-60℃, the pH is about 1, and the main corrosive elements are: HF, Cl-: 5500mg / L, H2SiF6 (containing a small amount of P2O5): 17-20%.

[0004] Hydrofluoric acid (HF) is an aqueous solution of hydrogen fluoride. It is a clear, colorless, fuming, corrosive liquid with a strong, pungent odor. Its melting point is -83.3°C, boiling point is 19.54°C, and flash point is 112.2°C. It is readily soluble in water and ethanol. Because hydrogen and fluorine atoms strongly bond, and hydrogen bonds exist between hydrofluoric acid molecules in aqueous solution, hydrofluoric acid cannot be completely ionized in water, so theoretically, low concentrations of hydrofluoric acid are weak acids. Hydrofluoric acid is extremely corrosive and can strongly corrode metals, glass, and silicon-containing objects. As the mass fraction of the HF solution increases, the corrosion rate of HF on carbon steel first increases and then decreases. At low concentrations, it is weakly acidic due to the formation of hydrogen bonds. However, at concentrations above 5 mol / L, self-ionization occurs, making hydrofluoric acid a very strong acid. Liquid hydrogen fluoride is a very strong acid, comparable in acidity to sulfuric acid in sewage, but weaker than fluorosulfonic acid. Highly corrosive, especially to silicon compounds.

[0005] Fluorine is a reactive nonmetal with strong oxidizing power. Furthermore, the radius of the fluoride ion in hydrofluoric acid is very small, smaller than that of the oxygen ion. This makes it highly permeable, and even dense oxides cannot prevent its penetration. The difficulty in using hydrofluoric acid for corrosion prevention lies in its combination of the strong corrosiveness of other strong acids and the unique properties of the fluoride ion. Therefore, hydrofluoric acid not only corrodes metals but also reacts with silicon and silicides to form gaseous silicon tetrafluoride, which can corrode glass, ceramics, and their derivatives. In actual industrial applications, hydrofluoric acid is particularly destructive to water pump seals.

[0006] like Figure 1 As shown in the figure, the most commonly used seals on water pumps are double-end mechanical seals, including:

[0007] Dynamic ring 1: The dynamic ring material can be high alloy steel, cemented carbide, cast iron, etc. In corrosive media, stainless steel surface is generally welded with cemented carbide or new silicon carbide (tungsten) ceramics.

[0008] Stationary ring 2: The stationary ring material can be cast iron, bronze alloy, or impregnated graphite or polytetrafluoroethylene.

[0009] Spring device 3: usually made of metal, no specific requirements are mentioned, the main function is to maintain the buffer contact between the end faces of the dynamic and static rings with appropriate spring pressure ratio.

[0010] Auxiliary seal 4: The types include O-ring, V-ring, square ring, trapezoidal ring, etc.; the materials include artificial synthetic rubber, such as nitrile, fluororubber, EPDM, etc.

[0011] As can be seen, the materials used for mechanical seal bearings are mainly tungsten carbide, 1Cr13 welded cobalt-chromium tungsten, resin-impregnated graphite, tungsten carbide, and cermet. The mechanical seal base and spring are mainly made of stainless steel. These materials are not effective in resisting hydrofluoric acid corrosion.

[0012] Under these operating conditions, a single-end seal, even one made of 2205 stainless steel, wouldn't last more than a week. Double-end seals, on the other hand, offer significantly better performance because their bases don't come into direct contact with the fluid. However, because the bearings are primarily made of tungsten carbide, graphite, and ceramic, the inner pair of bearings typically fail within a month. Furthermore, because the flushing water pressure for the double-end seals is generally greater than the internal pressure in the pump cavity, no leakage is observed to the outside, but rather the flushing water leaks inwards into the pump's outlet water. This is acceptable in practice and has been used to this day. However, double-end seals are expensive and, in this case, lack true double-end seal functionality. Each repair requires complete disassembly of the pump to replace the seals, which is time-consuming and labor-intensive.

[0013] Therefore, how to achieve the same sealing effect is a technical problem that needs to be solved urgently. Utility Model Content

[0014] The utility model provides a pump shaft seal assembly structure, aiming to solve at least one defect of the above-mentioned existing double-end face mechanical seal.

[0015] The utility model relates to a pump shaft seal combination structure, comprising:

[0016] A mechanical seal assembly is provided at one end of the main shaft and is used to mechanically seal the one end of the main shaft;

[0017] The packing seal assembly is arranged at the other end of the main shaft and is used for packing and sealing the other end of the main shaft; the packing seal assembly includes a stuffing box, which is sleeved on the main shaft and has a stuffing cavity arranged near the main shaft.

[0018] Furthermore, a first filler injection hole is provided above the filler box.

[0019] Furthermore, the filler cavity is filled with mud-like filler.

[0020] Furthermore, the stuffing seal assembly further includes a stuffing box body sleeved on the stuffing box, and the stuffing box body is provided with a second stuffing injection hole corresponding to the position of the first stuffing injection hole.

[0021] Furthermore, the mechanical seal assembly includes a first mechanical seal base, a second mechanical seal base, a spring device, a mechanical seal dynamic ring and a mechanical seal static ring. The spring device is arranged between the first mechanical seal base and the second mechanical seal base. One end of the mechanical seal dynamic ring is connected to an end of the second mechanical seal base away from the first mechanical seal base, and the other end of the mechanical seal dynamic ring is connected to the mechanical seal static ring.

[0022] Furthermore, the static ring of the mechanical seal is sleeved in the mechanical seal gland, and the mechanical seal gland is fixedly connected to the end of the stuffing box body.

[0023] Furthermore, the stuffing box is fixedly connected to the stuffing box body.

[0024] Furthermore, the gap between the stuffing box and the main shaft is 0.15 to 0.4 mm.

[0025] Furthermore, the length of the stuffing box is 12 to 30 mm.

[0026] Furthermore, the thickness of the stuffing box is 18 to 25 mm.

[0027] The beneficial effects achieved by the utility model are:

[0028] The utility model provides a pump shaft seal combination structure, which adopts a mechanical seal component and a packing seal component. The mechanical seal component is arranged at one end of the main shaft and is used to mechanically seal the one end of the main shaft; the packing seal component is arranged at the other end of the main shaft and is used to pack and seal the other end of the main shaft; the packing seal component includes a stuffing box, which is sleeved on the main shaft, and a stuffing cavity is provided in the stuffing box near the main shaft. The pump shaft seal combination structure provided by the utility model changes the original double-end mechanical seal into a single-end mechanical seal, and is made of general materials with low modification cost; a stuffing box is installed at the end of the stuffing box body near the impeller, and the stuffing box is used to keep the mud-like stuffing in the correct shape, so that it does not undergo plastic deformation during operation, flow into the inside of the pump body, or flow to the position of the mechanical seal, thereby affecting the sealing surface of the mechanical seal and causing water leakage of the mechanical seal, and the sealing effect is good; a hole is opened on the stuffing box, which is opposite to the hole on the stuffing box body, and the mud-like stuffing is injected into the stuffing box through this hole, which is convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural diagram of an existing double-end mechanical seal;

[0030] Figure 2 This is a structural diagram of an embodiment of a pump shaft seal assembly structure of the utility model;

[0031] Figure 3 This is a schematic diagram of an external pipe connection of an embodiment of a pump shaft seal assembly structure of the utility model;

[0032] Figure 4 This is a schematic diagram of key dimension control of an embodiment of a pump shaft seal assembly structure of the utility model;

[0033] Figure 5 for Figure 4 A magnified schematic diagram of part A in the middle.

[0034] Description of Figure Numbers:

[0035] 10. Mechanical seal assembly; 20. Stuffing seal assembly; 21. Stuffing box; 211. Stuffing cavity; 212. First stuffing injection hole; 22. Stuffing box body; 221. Second stuffing injection hole; 11. First mechanical seal base; 12. Second mechanical seal base; 13. Spring device; 14. Mechanical seal dynamic ring; 15. Mechanical seal static ring; 16. Mechanical seal cover; 30. Main shaft. DETAILED DESCRIPTION

[0036] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] like Figure 2 and Figure 3As shown, the first embodiment of the present invention proposes a pump shaft seal combination structure, including a mechanical seal assembly 10 and a packing seal assembly 20, wherein the mechanical seal assembly 10 is arranged at one end of the main shaft 30, and is used to mechanically seal the one end of the main shaft 30; the packing seal assembly 20 is arranged at the other end of the main shaft 30, and is used to pack the other end of the main shaft 30; the packing seal assembly 20 includes a stuffing box 21, which is sleeved on the main shaft, and a stuffing cavity 211 is provided in the stuffing box 21 near the main shaft.

[0038] In the above structure, see Figures 2 to 5 The pump shaft seal assembly structure provided in this embodiment has a first packing injection hole 212 provided above the stuffing box 21. The stuffing cavity 211 is injected with muddy packing. Preferably, the stuffing cavity 211 is injected with white muddy packing. The stuffing seal assembly 20 also includes a stuffing box body 22 sleeved on the stuffing box 21, and the stuffing box body 22 is provided with a second stuffing injection hole 221 corresponding to the position of the first packing injection hole 212. The pump shaft seal assembly structure provided in this embodiment is easy to install and can be maintained without stopping the pump; there is no fixed specification, which is convenient for storage and procurement; it does not wear the shaft sleeve, reducing the maintenance workload.

[0039] Further, see Figures 2 to 5 The pump shaft seal assembly structure provided in this embodiment comprises a mechanical seal assembly 10 including a first mechanical seal base 11, a second mechanical seal base 12, a spring device 13, a mechanical seal dynamic ring 14 and a mechanical seal static ring 15. The spring device 13 is arranged between the first mechanical seal base 11 and the second mechanical seal base 12. One end of the mechanical seal dynamic ring 14 is connected to the end of the second mechanical seal base 12 away from the first mechanical seal base 11, and the other end of the mechanical seal dynamic ring 14 is connected to the mechanical seal static ring 15. The mechanical seal static ring 15 is sleeved in the mechanical seal pressure cover 16, and the mechanical seal pressure cover 16 is fixedly connected to the end of the stuffing box body 22. The stuffing box 21 is fixedly connected to the stuffing box body 22. The gap between the stuffing box 21 and the main shaft is 0.15 to 0.4 mm. The length of the stuffing box 21 is 12 to 30 mm. The thickness of the stuffing box 21 is 18 to 25 mm. The pump shaft seal assembly structure provided in this embodiment changes the original double-end mechanical seal into a single-end mechanical seal, and is made of general materials, with low modification costs; a stuffing box 21 is installed on the stuffing box body 22 near the impeller end, and the stuffing box 21 is used to keep the muddy filler in the correct shape and prevent it from being plastically deformed during operation, flowing into the pump body, or flowing to the mechanical seal position, thereby affecting the sealing surface of the mechanical seal and causing water leakage in the mechanical seal, and the sealing effect is good; a hole is opened on the stuffing box, which is opposite to the hole on the stuffing box body 22, and the muddy filler is injected into the stuffing box 21 through this hole, which is convenient to use.

[0040] like Figures 2 to 5 As shown, the pump shaft seal assembly structure provided in this embodiment has the following working principle:

[0041] The main change of this technical solution is to replace one end of the double-end mechanical seal with a mud-like filler, that is, to replace the end face of the double-end mechanical seal that is in direct contact with the medium with a mud-like filler.

[0042] Mud packing (also known as "injection packing, layered shear soft packing, liquid packing, flexible graphite packing mud, packing mud, sealing soft mud") is a mud packing synthesized and produced by strict process from high-strength flocculent artificial synthetic fiber high-purity dispersion, special sealant, lubricant, and can be produced according to the technical data required by the user. The mud packing feels smooth and looks like clay. It will not affect the color of water after contact with water. It is an upgraded product of pump packing.

[0043] 1. Advantages of using mud filler:

[0044] 1. Easy to install and can realize maintenance without stopping the pump.

[0045] 2. No fixed specifications, easy to store and purchase.

[0046] 3. No wear on the sleeve, reducing maintenance workload.

[0047] Generally speaking, there are two types of soft fillers: white mud fillers and black mud fillers. In this embodiment, white mud fillers are used. White sealing mud fillers are used for sealing valves and pumps in industrial fields such as industrial chemicals, food, drinking water, pharmaceuticals, petroleum, metallurgy, chemicals, fertilizers, power generation, papermaking, and water treatment.

[0048] 2. Characteristics of white mud filler:

[0049] 1. White sealing mud packing is made of white PTFE (Polytetrafluoroethylene) fiber mixed with FDA-approved lubricant. It is pollution-free, non-toxic, and food-grade. It changes the packing-based packing sealing model and is suitable for all packing sealing devices in the factory without any specification restrictions.

[0050] 2. There is no need for stringent precision requirements on the stuffing box and shaft, and it is particularly suitable for sealing worn shafts.

[0051] Technical parameters of white mud filler:

[0052] Temperature: -40℃—260℃;

[0053] Pressure: 30MPa;

[0054] Chemical resistance: pH 0-14;

[0055] Physical resistance: Maximum shaft speed 20m / s

[0056] Packaging specifications: 2kg / barrel, 5kg / barrel.

[0057] 3. Specific transformation plan:

[0058] 1. Change the original double-end mechanical seal to a single-end mechanical seal made of general material.

[0059] 2. Install a stuffing box on the stuffing box body near the impeller end.

[0060] The main function of the stuffing box is to keep the muddy stuffing in the correct shape and prevent it from being plastically deformed during operation, flowing into the pump body, or flowing to the mechanical seal position, thereby affecting the sealing surface of the mechanical seal and causing the mechanical seal to leak.

[0061] 3. A hole is opened on the stuffing box, which is opposite to the hole on the stuffing box body. The muddy stuffing is injected into the stuffing box through this hole.

[0062] 4. Determination of key dimensions, as shown in Table 1:

[0063] Table 1 Key Dimension Determination Table

[0064]

[0065]

[0066] 5. Usage and operation method:

[0067] 1. Before starting the machine, use a mud-like filler injection gun to inject the filler into the stuffing box from the injection hole on the stuffing box body.

[0068] 2. Open the inlet and outlet valves of the stuffing box and monitor the pressure gauge behind the inlet valve. Control the inlet and outlet valves to ensure that the pressure is greater than the pressure inside the pump cavity. (Note that the corresponding position of the pump cavity is located within the sealing ring area for some pumps. In this case, the corresponding pressure at this position is the pump inlet pressure.) If the inlet pressure is p1, the pressure on this pressure gauge is generally p1+0.05MPa-p1+0.1MPa. If it is too large, leakage will increase. If it is too small, the corrosive medium in the pump cavity will enter the mechanical seal chamber and corrode the mechanical seal.

[0069] 3. When the pump is shut down, either drain the corrosive medium in the pump cavity or continue to supply water to the mechanical seal cavity to keep the pressure of the mechanical seal cavity greater than the pressure inside the pump. This will ensure that the mechanical seal is always operating in a clean water environment.

[0070] The pump shaft seal assembly structure provided in this embodiment, compared with the prior art, adopts a mechanical seal assembly and a packing seal assembly. The mechanical seal assembly is provided at one end of the main shaft for mechanically sealing the one end of the main shaft; the packing seal assembly is provided at the other end of the main shaft for packing sealing the other end of the main shaft; the packing seal assembly includes a stuffing box, which is sleeved on the main shaft, and a stuffing cavity is provided near the main shaft. The pump shaft seal assembly structure provided in this embodiment changes the original double-end mechanical seal into a single-end mechanical seal, and is made of general materials with low modification cost; a stuffing box is installed near the impeller end of the stuffing box body, and the stuffing box is used to keep the mud-like stuffing in the correct shape, so that it does not undergo plastic deformation during operation, flow into the pump body, or flow to the mechanical seal position, thereby affecting the sealing surface of the mechanical seal and causing water leakage of the mechanical seal, and the sealing effect is good; a hole is opened on the stuffing box, which is opposite to the hole on the stuffing box body, and the mud-like stuffing is injected into the stuffing box through this hole, which is convenient to use.

[0071] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Clearly, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, to the extent such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to encompass such changes and modifications.

Claims

1. A pump shaft seal assembly structure, characterized in that: include: A mechanical seal assembly (10) is provided at one end of the main shaft and is used to mechanically seal the one end of the main shaft; A packing seal assembly (20) is provided at the other end of the main shaft and is used for packing and sealing the other end of the main shaft; the packing seal assembly (20) includes a packing box (21), the packing box (21) is sleeved on the main shaft, and the packing box (21) is provided with a packing cavity (211) near the main shaft.

2. The pump shaft seal assembly structure according to claim 1, characterized in that: A first filler injection hole (212) is provided above the filler box (21).

3. The pump shaft seal assembly structure according to claim 2, characterized in that: The filler cavity (211) is filled with mud-like filler.

4. The pump shaft seal assembly structure according to claim 2, characterized in that: The stuffing seal assembly (20) further comprises a stuffing box body (22) sleeved on the stuffing box (21), wherein the stuffing box body (22) is provided with a second stuffing injection hole (221) corresponding to the position of the first stuffing injection hole (212).

5. The pump shaft seal assembly structure according to claim 4, characterized in that: The mechanical seal assembly (10) comprises a first mechanical seal base (11), a second mechanical seal base (12), a spring device (13), a mechanical seal dynamic ring (14) and a mechanical seal static ring (15), wherein the spring device (13) is arranged between the first mechanical seal base (11) and the second mechanical seal base (12), one end of the mechanical seal dynamic ring (14) is connected to an end of the second mechanical seal base (12) away from the first mechanical seal base (11), and the other end of the mechanical seal dynamic ring (14) is connected to the mechanical seal static ring (15).

6. The pump shaft seal assembly structure according to claim 5, characterized in that: The mechanical seal static ring (15) is sleeved in the mechanical seal gland (16), and the mechanical seal gland (16) is fixedly connected to the end of the stuffing box body (22).

7. The pump shaft seal assembly structure according to claim 6, characterized in that: The stuffing box (21) is fixedly connected to the stuffing box body (22).

8. The pump shaft seal assembly structure according to claim 7, characterized in that: The gap between the stuffing box (21) and the main shaft is 0.15-0.4 mm.

9. The pump shaft seal assembly structure according to claim 7, characterized in that: The length of the stuffing box (21) is 12-30 mm.

10. The pump shaft seal assembly structure according to claim 7, wherein: The thickness of the stuffing box (21) is 18-25 mm.

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