Combined seal of phosphoric acid axial flow pump

Abstract

The utility model discloses a phosphoric acid axial flow pump combined seal which comprises a main seal and an auxiliary seal, the main seal is arranged close to the atmosphere side, the auxiliary seal is arranged close to the medium side, the main seal is a dry gas seal, and the auxiliary seal is a mechanical seal arranged between the dry gas seal and a process medium. A cavity between the dry gas seal and the mechanical seal is filled with circulating water, and the dry gas seal is filled with compressed air. Circulating water is filled between the mechanical seal and the dry gas seal, heat generated by the end face of the mechanical seal is taken away, meanwhile, stable reference pressure is provided for the dry gas seal, the pressure of sealing gas can be set for the dry gas seal according to the pressure of the circulating water, the pressure of the circulating water is stable, and therefore the pressure of the dry gas seal is relatively stable. The stable operation of the dry gas seal cannot be influenced by the fluctuation of the process medium pressure, the service life of the sealing device is prolonged, and the shutdown overhaul times of the axial flow pump caused by sealing faults are reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of phosphoric acid production, and in particular relates to a phosphoric acid axial flow pump combined seal. Background Art

[0002] In the production process of wet phosphoric acid, the concentration device often uses axial flow pumps to force circulation to concentrate dilute phosphoric acid. Axial flow pumps are mostly horizontal pumps. The matching of performance parameters such as head and flow rate and the stability of equipment operation directly affect the production load of the concentration device. Reducing the failure rate of axial flow pumps and improving the performance parameters of equipment are the main problems faced by wet phosphoric acid concentration devices.

[0003] Through failure statistics, it is found that the axial flow pump shutdown and maintenance caused by sealing device problems accounts for more than 80% of the axial flow pump failure rate, that is, the reliability of the sealing device will directly affect the stability of the axial flow pump operation. At present, packing seals, double-end mechanical seals, and floating rings with dry gas seals are commonly used sealing methods, but they all have the problem of short service life. Utility Model Content

[0004] The purpose of the utility model is to overcome the defects of the prior art and provide a combined seal for a phosphoric acid axial flow pump. Circulating water is filled between the mechanical seal and the dry gas seal to take away the heat generated by the end face of the mechanical seal and provide a stable reference pressure for the dry gas seal. The dry gas seal can set the pressure of the sealing gas according to the pressure of the circulating water. The circulating water pressure is stable, so the pressure of the dry gas seal is also relatively stable. Fluctuations in the process medium pressure will not affect the stable operation of the dry gas seal, thereby increasing the service life of the sealing device and reducing the number of axial flow pump shutdowns and maintenance times due to sealing failures.

[0005] The purpose of the utility model is achieved through the following technical solutions:

[0006] A combined seal for a phosphoric acid axial flow pump comprises a main seal and an auxiliary seal, wherein the main seal is arranged close to the atmosphere side, and the auxiliary seal is arranged close to the medium side. The main seal is a dry gas seal, and the auxiliary seal is a mechanical seal arranged between the dry gas seal and the process medium. The cavity between the dry gas seal and the mechanical seal is filled with circulating water, and the dry gas seal is filled with compressed air.

[0007] In one embodiment, the dry gas seal includes two groups of dynamic sealing structures, each group of the dynamic sealing structures includes a static ring and a dynamic ring, the static ring and the dynamic ring in each group of dynamic sealing structures form a dynamic sealing surface, and the compressed air is filled between the dynamic sealing surfaces of the two groups of dynamic sealing structures.

[0008] In one embodiment, the auxiliary seal includes a dynamic ring assembly and a stationary ring assembly, and the dynamic ring assembly and the stationary ring assembly form a dynamic sealing surface.

[0009] In one embodiment, the dynamic sealing structure further includes a push ring in contact with the dynamic ring, and a spring is provided between the push rings of the two sets of dynamic sealing structures, and the spring is installed on a spring seat.

[0010] In one embodiment, a dynamic pressure groove is further formed on the end surface of the stationary ring.

[0011] In one embodiment, the compressed air is nitrogen, the pressure provided by the circulating water to the dry gas seal is a reference pressure, and the pressure of the compressed air is 0.2-0.3 MPa higher than the reference pressure.

[0012] In one embodiment, the mechanical seal is a double-balanced structure, and when the process medium pressure is greater than or less than the circulating water pressure, the mechanical seal is a balanced structure.

[0013] In one embodiment, it also includes a pressure plate arranged on the shaft sleeve, a dynamic ring seat is arranged on the pressure plate, and the dynamic ring assembly is connected to the dynamic ring seat through a pin shaft.

[0014] The beneficial effects of the utility model are:

[0015] (1) Circulating water is filled between the mechanical seal and the dry gas seal to take away the heat generated by the end face of the mechanical seal and provide a stable reference pressure for the dry gas seal. The dry gas seal can set the pressure of the sealing gas according to the pressure of the circulating water. The circulating water pressure is stable, so the pressure of the dry gas seal is also relatively stable. The fluctuation of the process medium pressure will not affect the stable operation of the dry gas seal, thereby increasing the service life of the sealing device and reducing the number of shutdowns and maintenance of the axial flow pump due to sealing failures;

[0016] (2) The dry gas seal is used as the main seal. Two sets of dynamic sealing structures form a dynamic sealing surface. The dynamic pressure grooves on the end face of the static ring realize non-contact operation of the sealing surface and extend the service life of the sealing device. Compressed air is filled between the dynamic sealing surfaces of the two sets of dynamic sealing structures to prevent the process medium (circulating water) from leaking to the atmosphere (environment), thereby achieving a sealing effect.

[0017] (3) Mechanical seals are used as auxiliary seals. The dynamic sealing surface formed by the static ring assembly and the dynamic ring assembly can effectively prevent the process medium from leaking into the circulating water (or the circulating water from leaking into the process medium). At the same time, it can also block the acid slag (particulate matter) in the process medium from entering the dry gas sealing part. The mechanical seal is a double-balanced structure. When the process medium pressure is greater than the circulating water pressure, the seal is a balanced structure. When the process medium pressure is less than the circulating water pressure, the seal is also a balanced structure. The operation of the seal is not affected by the process medium pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present utility model will be described in more detail below based on embodiments with reference to the accompanying drawings.

[0019] Wherein:

[0020] Figure 1 A structural schematic diagram of the present utility model is shown;

[0021] Figure 2 A structural schematic diagram of the stationary ring of the present utility model is shown;

[0022] Figure 3 A structural schematic diagram of the rotating ring of the present utility model is shown;

[0023] Figure 4 A structural schematic diagram of the rotating ring assembly of the present utility model is shown;

[0024] Figure 5 A structural schematic diagram of the stationary ring assembly of the present utility model is shown;

[0025] In the accompanying drawings, the same components are denoted by the same reference numerals. The drawings are not drawn to actual scale.

[0026] Reference numerals:

[0027] 1 - stationary ring, 2 - rotating ring, 3 - rotating ring assembly, 4 - stationary ring assembly, 5 - push ring, 6 - spring, 7 - spring seat, 8 - pressing plate, 9 - rotating ring seat, 10 - pin shaft, 11 - O-ring. Detailed implementation manners

[0028] The present utility model will be further described below in conjunction with the accompanying drawings.

[0029] The present utility model provides a combined seal for a phosphoric acid axial flow pump, as Figures 1 to 5 shown, including a main seal and an auxiliary seal. The main seal is arranged near the atmosphere side, and the auxiliary seal is arranged near the medium side. The main seal is a dry gas seal, and the auxiliary seal is a mechanical seal arranged between the dry gas seal and the process medium. The cavity between the dry gas seal and the mechanical seal is filled with circulating water, and compressed air is filled inside the dry gas seal;

[0030] Specifically, the dry gas seal includes two sets of dynamic seal structures. Each set of dynamic seal structures includes a stationary ring 1 and a rotating ring 2. The stationary ring 1 and the rotating ring 2 in each set of dynamic seal structures form a dynamic seal surface. Compressed air is filled between the dynamic seal surfaces of the two sets of dynamic seal structures. A dynamic pressure groove is also provided on the end face of the stationary ring 1;

[0031] It should be noted that the dry gas seal is used as the main seal, and two sets of dynamic sealing structures form a dynamic sealing surface. The dynamic pressure groove opened on the end face of the static ring 1 realizes non-contact operation of the sealing surface and prolongs the service life of the sealing device. Compressed air is filled between the dynamic sealing surfaces of the two sets of dynamic sealing structures to prevent the process medium (circulating water) from leaking to the atmosphere (environment), thereby achieving a sealing effect. Circulating water is filled between the mechanical seal and the dry gas seal to take away the heat generated by the end face of the mechanical seal and provide a stable reference pressure for the dry gas seal. The dry gas seal can set the pressure of the compressed air according to the pressure of the circulating water. The circulating water pressure is stable, so the pressure of the dry gas seal is also relatively stable. The fluctuation of the process medium pressure will not affect the stable operation of the dry gas seal, thereby improving the service life of the sealing device, reducing the number of axial flow pump shutdowns and maintenance due to sealing failures, reducing the entry of process water into the process medium, and reducing the load of subsequent evaporation and concentration processes, thereby improving the operation efficiency of the entire phosphoric acid concentration device;

[0032] Furthermore, the auxiliary seal includes a dynamic ring assembly 3 and a static ring assembly 4, the dynamic ring assembly 3 and the static ring assembly 4 form a dynamic sealing surface, the dynamic sealing structure also includes a push ring 5 in contact with the dynamic ring, a spring 6 is arranged between the push rings 5 of the two sets of dynamic sealing structures, and the spring 6 is installed on a spring seat 7;

[0033] In one embodiment, the compressed air is nitrogen, and the pressure provided by the circulating water to the dry gas seal is the reference pressure. The pressure of the compressed air is 0.2-0.3 MPa higher than the reference pressure, that is, the pressure of the compressed air is set according to the pressure of the circulating water. The pressure of the circulating water can be adjusted by the inlet and outlet valves. When the process medium pressure is greater than the circulating water pressure, a small amount of process medium will leak into the circulating water. When the process medium pressure is less than the circulating water pressure, a small amount of circulating water will leak into the process medium. A small amount of process medium leaking into the circulating water (or circulating water leaking into the process medium) will not affect the pressure of the circulating water. When the process medium pressure fluctuates greatly, the circulating water can establish a stable reference pressure between the dry gas seal and the process medium. The main seal dry gas seal can set the pressure of the sealing gas according to the pressure of the circulating water. Since the circulating water pressure is stable, the pressure of the dry gas seal is also relatively stable, and the fluctuation of the process medium pressure will not affect the stable operation of the dry gas seal.

[0034] In one embodiment, the mechanical seal is of a double-balanced structure. When the process medium pressure is greater than or less than the circulating water pressure, the mechanical seal is of a balanced structure. It further includes a pressing plate 8 arranged on the shaft sleeve. A moving ring seat 9 is arranged on the pressing plate 8. The moving ring assembly 3 is connected to the moving ring seat 9 through a pin shaft 10. The dynamic sealing surface formed by the stationary ring assembly 4 and the moving ring assembly 3 of the mechanical seal can effectively prevent a large amount of process medium from leaking into the circulating water (or circulating water from leaking into the process medium). At the same time, it can also block the acid slag (particulates) in the process medium from entering the dry gas seal part. The mechanical seal is of a double-balanced structure. When the process medium pressure > the circulating water pressure, the seal is of a balanced structure. When the process medium pressure < the circulating water pressure, the seal is also of a balanced structure. The operation of this seal is not affected by the process medium pressure. The mechanical seal belongs to end face seal and has excellent sealing performance. Under normal circumstances, the leakage amount of circulating water into the process medium is less than 1 / 1000 of that of packing seal and floating ring seal;

[0035] In one embodiment, an O-ring 11 is arranged between the moving ring assembly 3 and the moving ring seat for sealing, and an O-ring 11 is also arranged at the end of the stationary ring 1 for sealing;

[0036] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention 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 to the present invention.

[0037] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. An axial-flow phosphoric acid pump combined seal, characterized in that, It includes a main seal and an auxiliary seal. The main seal is arranged near the atmosphere side, and the auxiliary seal is arranged near the medium side. The main seal is a dry gas seal, and the auxiliary seal is a mechanical seal arranged between the dry gas seal and the process medium. The cavity between the dry gas seal and the mechanical seal is filled with circulating water, and compressed air is filled inside the dry gas seal.

2. The combined seal of a phosphoric acid axial flow pump according to claim 1, characterized in that, The dry gas seal includes two groups of dynamic seal structures. Each group of the dynamic seal structures includes a stationary ring and a rotating ring. The stationary ring and the rotating ring in each group of the dynamic seal structures form a dynamic seal face, and the compressed air is filled between the dynamic seal faces of the two groups of dynamic seal structures.

3. The combined seal of an axial flow phosphoric acid pump according to claim 1, characterized in that, The auxiliary seal includes a rotating ring assembly and a stationary ring assembly, and the rotating ring assembly and the stationary ring assembly form a dynamic seal face.

4. The combined seal of a phosphoric acid axial flow pump according to claim 2, characterized in that, The dynamic seal structure further includes a thrust ring in contact with the rotating ring. A spring is arranged between the thrust rings of the two groups of dynamic seal structures, and the spring is installed on a spring seat.

5. The combined seal of an axial flow phosphoric acid pump according to claim 2, characterized in that, Dynamic pressure grooves are also provided on the end face of the stationary ring.

6. The combined seal of an axial flow phosphoric acid pump according to claim 2, characterized in that, The compressed air is nitrogen. The pressure provided by the circulating water to the dry gas seal is the reference pressure, and the pressure of the compressed air is 0.2 - 0.3 MPa higher than the reference pressure.

7. The combined seal of an axial flow phosphoric acid pump according to claim 3, characterized in that, The mechanical seal is a double-balanced structure. When the process medium pressure is greater than or less than the circulating water pressure, the mechanical seal is a balanced structure.

8. The combined seal of an axial flow phosphoric acid pump according to claim 7, characterized in that, It further includes a pressing plate arranged on the shaft sleeve. A rotating ring seat is arranged on the pressing plate, and the rotating ring assembly is connected to the rotating ring seat through a pin shaft.

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