CN101975168A - Horizontal axial-suction sectional multistage high-pressure centrifugal pump - Google Patents

Abstract

A horizontal and axial suction segmental multi-stage high-pressure centrifugal pump, including a pump casing assembly, a rotor assembly, a bearing assembly, and a sealing cover, wherein the pump casing assembly is composed of a suction section casing, an intermediate section casing, and a discharge section connected in sequence. The rotor assembly consists of a first-stage impeller, a secondary impeller, guide vanes, and a rotating shaft. A sliding bearing (5) and a first-stage impeller seal ring (44) are provided at the first-stage impeller (6) or at the first-stage A sliding bearing (5) and a shaft sleeve (43) are provided at the guide vane (42); a balance drum (18) is installed in the casing (15) of the discharge section and on the rotating shaft (25). A balance sleeve (16) and a balance sleeve pressing plate (17) are installed, and there are gaps between the balance drum and the balance sleeve, and between the balance drum and the balance sleeve pressing plate. The invention can make the high-pressure pump run in a well-balanced manner, and improves the operation reliability and balance of the high-pressure pump. And compact structure, simple installation, easy maintenance, especially suitable for reverse osmosis seawater desalination system.

Description

Horizontal axial suction segmental multistage high pressure centrifugal pump

technical field

The invention relates to a pump product, in particular to a segmental multistage high-pressure centrifugal pump applied to reverse osmosis seawater desalination systems and industrial power plant water supply.

Background technique

The application of reverse osmosis as one of the mainstream seawater desalination methods in the world today accounts for an increasing proportion in seawater desalination projects, especially in my country, where the proportion of reverse osmosis is more than 80%. Among them, osmotic membrane, high-pressure pump and energy recovery device are the three core technologies of reverse osmosis seawater desalination. As one of the three core technologies, the high-pressure pump provides a pressure of more than 6-12MPa for the seawater permeable membrane. At present, the flow rate of the reverse osmosis seawater desalination high-pressure pump that processes 10,000 tons of seawater per day is 210-420m ³ /h, and the head is 550-700m. For such high-pressure pumps with medium and large flows, the pump efficiency can reach 75-80% when using segmental multi-stage high-pressure centrifugal pumps. Because the structure of the pump is simple, small in size, light in weight and cheap in price, it is suitable for reverse osmosis seawater desalination projects.

At present, both ends of the segmental multi-stage high-pressure centrifugal pump are equipped with oil bearing components, and there are two sets of shaft seal mechanisms at both ends. The pump is relatively long. It uses a single balance disc to balance the axial force, and the pump operation reliability is poor. The high-pressure pump used in the seawater desalination project requires a simpler and more reliable structure. It is hoped that the installation area will be small and the assembly and disassembly will be more convenient. Considering the reliable operation of the high-pressure pump, it is necessary to improve the original structure.

The high-pressure pump is one of the key equipment of the reverse osmosis seawater desalination system. The desalination system is very important. At present, my country's seawater desalination industry has just started, and the high-pressure pumps in the existing seawater desalination systems mainly rely on imports, so the development of high-pressure pumps for seawater desalination is of great significance to the development of my country's seawater desalination industry.

Contents of the invention

In order to overcome the above disadvantages, the present invention provides a horizontal and axial suction segmental multistage high-pressure centrifugal pump with compact structure, reliable operation, good balance, simple installation and convenient maintenance, and can be used in reverse osmosis seawater desalination system application.

The purpose of the present invention is achieved through the following technical solutions: a horizontal axial suction segmental multi-stage high-pressure centrifugal pump, comprising a pump housing assembly, a rotor assembly, a bearing assembly, and a sealing cover, wherein the pump housing assembly is sequentially connected by The suction section shell, the middle section shell, and the discharge section shell are composed. The rotor assembly is a segmented structure with multi-stage impellers arranged in the same direction, including the first stage impeller, secondary impeller, guide vane, and rotating shaft. The impeller is provided with a sliding bearing and the sealing ring of the first stage impeller or a sliding bearing and a shaft sleeve are provided at the first stage guide vane; a balance drum is installed in the casing of the discharge section and on the rotating shaft. The periphery of the drum is equipped with a balance sleeve and a balance sleeve pressure plate, and there are gaps between the balance drum and the balance sleeve, and between the balance drum and the balance sleeve pressure plate.

After adopting the structure of the present invention, since a pair of sliding bearings are arranged at the first-stage impeller or at the first-stage guide vane, the sliding bearings can overcome a large supporting force, so that the high-pressure pump can run well in balance; due to the arrangement The axial force balance mechanism composed of a balance drum, a balance sleeve, and a balance sleeve pressure plate is introduced, which improves the reliability and balance of the high-pressure pump operation. Moreover, the invention has the advantages of compact structure, simple installation and convenient maintenance, and is especially suitable for a reverse osmosis seawater desalination system. The successful research and development of the high-pressure pump has achieved localization and formed independent intellectual property rights, overcoming the passive situation of foreign technology blockade, and has significant technological progress and beneficial effects.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic cross-sectional structure diagram of a horizontal axial suction segmental multi-stage high-pressure centrifugal pump of the present invention.

FIG. 2 is an enlarged schematic view of the installation of the rotor assembly and the balance drum of the axial force balance mechanism in FIG. 1 .

Fig. 3 is an enlarged schematic view showing that the sliding bearing of the present invention is arranged at the first-stage impeller and is connected with the casing of the suction section and the sealing ring of the first-stage impeller.

Fig. 4 is an enlarged schematic view showing that the sliding bearing of the present invention is arranged at the first-stage guide vane and connected with the shaft sleeve and the rotating shaft.

Fig. 5 is an enlarged schematic view of the sliding bearing of the present invention.

Fig. 6 is a schematic view (enlarged) of the installation structure of the axial force balance mechanism in Fig. 1 on the rotating shaft.

Detailed ways

With reference to the accompanying drawings, it can be seen that the horizontal axial suction segmental multistage high-pressure centrifugal pump of the present invention includes a pump housing assembly, a rotor assembly 22, a bearing assembly 21, and a sealing cover 19, wherein the pump housing assembly is composed of successively connected suction section shells. Body 1, middle section casing 8, and spit section casing 15 (as shown in Fig. Clamp and fix the middle casing 8), the rotor assembly is a segmented structure with multi-stage impellers arranged in the same direction and includes the primary impeller 6, secondary impeller 11 (several), guide vanes 7 (several, including the first first-stage guide vane 42, last-stage guide vane 14), rotating shaft 25 (as shown in Figure 2), a sliding bearing 5 and a first-stage impeller seal ring 44 (ie, the first-stage impeller seal ring 44 is mounted on the first-stage impeller 6, and the sliding bearing 5 is located between the first-stage impeller seal ring 44 and the inner wall of the suction section housing 1, as shown in Figure 3) or a sliding bearing 5 is provided at the first-stage guide vane 42 Bearing 5 and shaft sleeve 43 (that is, shaft sleeve 43 is installed on the rotating shaft 25, and sliding bearing 5 is between the shaft sleeve 43 and the first-stage guide vane 42, as shown in Figure 4); , and a balance drum 18 is installed on the rotating shaft 25, and a balance sleeve 16 and a balance sleeve pressure plate 17 are installed on the periphery of the balance drum 18. Between the balance drum 18 and the balance sleeve 16, between the balance drum 18 and the balance sleeve pressure plate 17 There are (tiny) gaps between them (as shown in Figure 1 and Figure 6).

As shown in Figure 3, a pair of sliding bearings is formed by the sliding bearing 5 and the first-stage impeller sealing ring 44. The sliding bearing 5 of this structure also has the pressure water of the first-stage impeller 6 passing through the sliding bearing 5 to the left, so the sliding bearing 5 also Under good hydrodynamic conditions, the sliding bearing can overcome a large supporting force, so that the high-pressure centrifugal pump can run smoothly and prolong the service life of the sliding bearing; as shown in Figure 4, or the sliding bearing 5 and the shaft sleeve 43 form a pair of sliding bearings (that is, as another embodiment), the shaft sleeve 43 is like the guide vane bushing 10 at other guide vanes (except the first-stage guide vane 42), the sliding bearing 5 It is also designed to pass the pressure water of the first-stage impeller 6 in the sliding bearing 5, the pressure water passes through the sliding bearing 5 from right to left, and returns to the first-stage impeller inlet 47 through the balance hole 46 of the first-stage impeller, so that it flows through the sliding The bearing 5 makes the sliding bearing 5 more capable of overcoming a larger supporting force, so that the high-pressure centrifugal pump can run well and smoothly, and is a type of sliding bearing that can bear a larger radial load. The above two types of sliding bearings need to calculate the bearing force to obtain the required supporting force at the sliding bearing, calculate the length-to-diameter ratio of the sliding bearing, the bearing eccentricity and the pressure distribution of the sliding bearing when the supporting force is required. These calculations are programmed by design and completed by computers. As shown in Figure 5, several ring-shaped grooves 54 are arranged on the working surface of the sliding bearing 5, and once there are fine particles in the flowing water, they can fall into the ring-shaped grooves without damaging the sliding bearing. working surface. The sliding bearing is made of polyetheretherketone (PEEK) material filled with carbon fiber graphite with excellent low friction coefficient and wear resistance, or the lining of the sliding bearing can be processed and manufactured by Sialon material widely used in high-pressure pumps.

As shown in Fig. 1 and Fig. 2, the direction of the liquid flow was originally set by radial suction and radial discharge. Now, in order to change the direction of the liquid flow and improve the flow state of the liquid, a shaft is arranged in the casing 1 of the suction section. There is a suction channel 38 in the direction, and a radial discharge channel 39 is provided in the casing 15 of the discharge section. The liquid flow is sucked in the axial direction and discharged in the radial direction, so it is called a horizontal axial suction type. The impeller and guide vane of the rotor assembly are mainly provided with the middle section casing 8 . The rotor assembly consists of primary impellers, secondary impellers (several), guide vanes (several), shafts, etc. Most of the guide vanes are located between the corresponding impellers (including primary impellers, secondary impellers) and the middle casing Between, the last stage guide vane is located between the last secondary impeller and the casing of the discharge section. Specifically: a first-stage impeller 6 and a plurality of secondary impellers 11 (not more than five) are arranged in sequence from left to right, and the first stage is set between the first-stage impeller 6 and the first secondary impeller 11 Guide vanes 42 , and then a guide vane 7 is placed between every two secondary impellers 11 , and the last guide vane 14 is arranged on the rightmost and final secondary impeller 37 . The liquid flow from the suction channel 38 of the suction section casing horizontally and axially flows into the first-stage impeller 6 obtains kinetic energy at the first-stage impeller 6 and enters the first-stage guide vane 42, converts the kinetic energy obtained by the first-stage impeller into potential energy, and The loss reaches the secondary impeller 11, and the transported liquid flow gains energy in turn, reaches the final guide vane 14 and enters the discharge channel 39 of the discharge section casing 15, thereby discharging the high-pressure liquid flow into the pipe network in the seawater desalination system .

As shown in Fig. 1 and Fig. 6, the balance drum 18 can rotate with the rotating shaft, and the balance sleeve 16 and the balance sleeve pressing plate 17 are all mounted on the spout section housing 15 without rotating with the shaft; the balance drum 18 can also It is divided into a horizontal balance small drum 48 and a vertical balance large drum 49. A balance sleeve 16 is provided on the outside of the balance small drum 48, and the balance sleeve 16 is located on the (left) side of the balance large drum 49. A balance sleeve pressure plate is provided on the outside of the balance large drum 49. 17. The balance sleeve pressure plate 17 is connected with the balance sleeve 16; the balance small drum 48, the balance drum 49, the balance sleeve 16, and the balance sleeve pressure plate 17 constitute an axial force balance mechanism, which is located at the last secondary impeller 37 Between the sealing cover 19 and in the balance chamber 31 formed by the discharge section housing 15 and the sealing cover 19 .

As shown in Figure 6, when the first stage and secondary impellers of the segmental multistage high-pressure centrifugal pump are distributed in the same direction, there must be axial force. Under the action of the axial force, the rotating shaft will move to the left, and after the axial force balance mechanism is provided, the balance mechanism will generate a balance force. When the axial force is greater than the balance force, the axial force balance mechanism together with the rotating shaft 25 moves to the left, at this time the axial gap (b ₀ ) between the balance drum 18 and the balance sleeve 16 decreases, the resistance of the liquid increases, and the amount of leaked water decreases , the pressure on the liquid flowing through the radial gap also decreases, and at this time the balance force of the balance drum increases until the balance force and the axial force are equal. Because the balance small drum 48 of the balance mechanism of the combined action balances out a part of the axial force earlier, the balance force of the balance drum 49 is reduced, so the liquid flow velocity in the balance drum axial gap is slowed down, so that the liquid flow flows through the constant Balance the radial clearance (b ₁ ) and length (l ₁ ) of the snare drum 48 to obtain a larger axial clearance (b ₀ ) between the balance drum 18 and the balance sleeve 16, so that the axial end surfaces of the balance drum 18 and the balance sleeve 16 It is not easy to collide, which reduces the wear of the axial end face and makes the axial force balance mechanism work more reliably. A sliding bearing bushing 50 is lined between the balance sleeve 16 and the balance small drum 48, which can also reduce the leakage of balance water in a small range and small radial clearance, so as to improve pump efficiency and pump operation. reliability. Increase the thickness of the balance drum 49, which forms a radial gap (b _w ) with the balance sleeve pressure plate 17, which can prevent the liquid from being vaporized at the outer periphery of the balance drum and the balance sleeve to cause dry friction on the end face, and further improve the reliability of the pump operation . On the rotating shaft 25, and at the outer side of the balance drum 18, a pressure sleeve 34, a lock nut 33 and a small round nut 32 are sequentially installed, so that the balance drum 18 is fastened on the rotating shaft 25, and the balancing drum utilizes the rotating shaft The key 36 on the shaft transmits the torque from the rotating shaft. An O-ring 35 is arranged between the balance drum 18 and the pressure sleeve 34 to prevent the high-pressure liquid from leaking from the axial direction, so as to avoid pressure release and damage the normal function of the balance mechanism. The locking nut 33 and the shaft head screw 4 are jointly tightened to fix the rotating shaft to prevent loosening. Stage impeller 37) and axle sleeve 43, balance drum 18, pressure sleeve 34 are in tight state, can not take place axial movement because of each nut looseness, to guarantee the normal operation of rotating shaft.

As shown in Figure 1, tail cover 52 is also housed in the rear portion of described spit section housing 15, on described rotating shaft 25, and seal chamber 30 place in sealing cover 19 is provided with mechanical seal mechanism 20 ( One), and the mechanical seal assembly 20 is a single-end cartridge mechanical seal assembly (mature corrosion-resistant, multi-spring quick-install type); the seal cover 19 is externally connected with a balance return pipe 9, and the other end of the balance return pipe 9 It connects with the working cavity 51 of the first stage impeller 6 in the suction section housing 1 . The sealing chamber 30 in the sealing cover 19 communicates with the balance chamber 31 of the axial force balance mechanism. The mechanical seal assembly 20 does not need external cooling water, and it relies on the balance water leaked from the axial force balance mechanism for flushing and cooling, and passes through The balance return pipe enables the balance water to return to the working cavity of the first stage impeller in the casing of the suction section after flushing the mechanical seal assembly.

As shown in Figure 1, the bearing assembly 21 is installed on the rotating shaft 25 and is located at the (right) side of the discharge section casing 15 and the tail cover 52, and the bearing assembly 21 (lubricated by lubricating oil) passes through the tail The cover 52 is integrated with the casing 15 of the discharge section, and the rolling ball bearing 28 bearing radial load and axial load is installed in the bearing body 53 of the bearing assembly 21, and the rolling ball bearing 28 is thrown by the oil throwing ring 26 driven by the rotating shaft. Lubricated with lubricating oil. The heat generated when the rolling ball bearing 28 works is dissipated in two ways: one is to dissipate heat through the radial heat dissipation ribs 40 outside the bearing body 53; Medium (such as normal temperature sea water) to dissipate heat. This ensures that the rolling ball bearing 28 not only supports the right-end rotor but also bears the residual axial force of the axial force balance mechanism, so as to meet the needs of the high-pressure pump operating under variable working conditions. The left and right ends of the rotating shaft of the high-pressure pump are supported by bearings respectively, the left end is supported by a sliding bearing 5, and the right end is supported by a rolling ball bearing 28 that bears radial load and bidirectional axial load.

When the segmental multistage high-pressure centrifugal pump (horizontal axial suction mode) of the present invention is actually working, the motor drives the rotating shaft 25 to rotate through the pump coupling 23 and the coupling key 24 . Thus, the primary impeller 6, multiple secondary impellers 11 and the final secondary impeller 37 rotate together with the rotating shaft 25, and the liquid entering from the suction channel 38 of the suction section housing 1 is under the centrifugal force of the primary impeller 6. , guided from the guide vane 7 into the secondary impeller 11, and finally discharged from the discharge channel 39 of the discharge section casing 15 by the final guide vane 14 in the form of high-pressure liquid. Since a pair of sliding bearings are arranged at the first-stage impeller or at the first-stage guide vane, the sliding bearings can overcome a large supporting force, so that the high-pressure pump can run well in balance; due to the balance of the axial force balance mechanism function, and the balance chamber 31 communicates with the first-stage impeller working chamber 51 through the balance return pipe 9 to balance the axial force of the rotating shaft and improve the reliability and balance of the high-pressure pump operation. The invention is suitable for high-pressure centrifugal pumps with a flow rate of ^100-800m3 /h and a lift of 500-900m, as high-pressure pumps for desalination of seawater and as high-pressure boiler feedwater pumps for industrial power plants with the same performance and outlet water temperature ≤ 140°C.

Claims (7)

1. A horizontal axial suction segmental multistage high-pressure centrifugal pump, comprising a pump housing assembly, a rotor assembly (22), a bearing assembly (21), a seal cover (19), wherein the pump housing assembly is connected in sequence The suction section casing (1), the middle section casing (8), and the discharge section casing (15), the rotor assembly is a segmented structure with multi-stage impellers arranged in the same direction and includes the first stage impeller (6), the secondary The impeller (11), guide vanes (7), and rotating shaft (25), are characterized in that a sliding bearing (5) and a first-stage impeller seal ring (44) are provided at the first-stage impeller (6) or at the first-stage impeller (6) A sliding bearing (5) and a shaft sleeve (43) are provided at the first-stage guide vane (42); a balance drum (18) is installed on the rotating shaft (25) in the casing (15) of the discharge section. The balance drum (18) is equipped with a balance sleeve (16) and a balance sleeve pressure plate (17). Between the balance drum (18) and the balance sleeve (16), the balance drum (18) and the balance sleeve pressure plate (17) ) with gaps between them. 2. The horizontal axial suction segmental multi-stage high-pressure centrifugal pump according to claim 1, characterized in that several annular grooves (54) are provided on the working surface of the sliding bearing (5). 3. The horizontal axial suction segmental multistage high-pressure centrifugal pump according to claim 1 or 2, characterized in that: an axial suction channel (38) is provided in the suction section housing (1), A radial discharge channel (39) is provided in the discharge section housing (15). 4. The horizontal axial suction segmental multistage high-pressure centrifugal pump according to claim 1, characterized in that: the balance drum (18) is divided into a horizontal balance drum (48) and a longitudinal balance drum (49) , the outside of this balance small drum (48) is provided with balance cover (16), and balance cover (16) is in the side of balance large drum (49) again, and the outside of this balance large drum (49) is established balance cover pressure plate (17), and balance cover The pressure plate (17) is connected with the balance sleeve (16); the balance small drum (48), the balance drum (49), the balance sleeve (16), and the balance sleeve pressure plate (17) constitute an axial force balance mechanism, and the balance mechanism It is between the last secondary impeller (37) and the sealing cover (19), and in the balance chamber (31) formed by the discharge section casing (15) and the sealing cover (19). 5. The horizontal axial suction segmental multi-stage high-pressure centrifugal pump according to claim 1 or 4, characterized in that: on the rotating shaft (25) and at the outer side of the balance drum (18) Pressure sleeve (34), lock nut (33) and small round nut (32) are housed, thereby balance drum (18) is fastened on the rotating shaft (25). 6. The horizontal axial suction segmental multistage high-pressure centrifugal pump according to claim 1, characterized in that: a tail cover (52) is also installed at the rear of the discharge section housing (15), and A mechanical seal mechanism (20) is provided on the above-mentioned rotating shaft (25) and at the seal cavity (30) in the seal cover (19), and the mechanical seal assembly (20) is a single-end cartridge mechanical seal assembly; The sealing cover (19) is externally connected with a balance return pipe (9), and the other end of the balance return pipe (9) is connected to the working chamber (51) of the first stage impeller (6) in the suction section housing (1). catch. 7. The horizontal axial suction segmental multistage high-pressure centrifugal pump according to claim 6, characterized in that: the bearing assembly (21) is installed on the rotating shaft (25) and is located in the casing of the discharge section ( 15) and the side of the tail cover (52), the bearing assembly (21) forms a whole through the tail cover (52) and the discharge section casing (15), and the rolling ball bearing (28 ) is installed in the bearing body (53) of the bearing assembly (21).

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