Multiphase pump in the form of a screw pump

Abstract

The invention relates to a multiphase pump of the screw pump design, comprising a screw housing (2) having a screw set (6) accommodated therein, which screw set comprises a drive screw (7) and at least one driven screw (9) meshing with the drive screw, via which screw set (6) a fluid to be conveyed can be conveyed from a suction side (S) at which the fluid is at a suction pressure (pS) to a pressure side (D) at which the fluid is at an elevated outlet pressure (pA), wherein the drive screw (7) and the driven screw (9) are each rotatably supported in the screw housing (2) via a bearing device, characterized in that the bearing device is a hydrodynamic plain bearing (15-18), wherein the drive screw (7) and the driven screw (9) are accommodated via a bearing gap (30, 31), wherein a supply device is provided for supplying a fluid lubricating medium having a pressure higher than the suction pressure (pS) into the respective bearing gap (30, 31).

Description

Background Technology

[0001] This type of multiphase pump is used to transport mixtures of different media. The mixture can be, for example, a liquid-gas mixture, such as a water-gas mixture or an oil-gas mixture, or a mixture of two different liquids, such as a water-oil mixture or a water-sand-oil mixture. This type of multiphase pump is often designed as a screw pump. Such a screw pump includes a screw housing, typically housed within a casing, in which a screw assembly is arranged. The screw assembly includes a drive screw connected to an external drive motor. In addition, at least one driven screw is provided, wherein both the drive screw and the driven screw have corresponding screw profiles, and the screw profiles mesh with each other so that the drive screw drives the driven screw, thereby transporting the fluid (i.e., the mixture described herein). Typically, two driven screws are provided, arranged 180° off from the drive screw and both meshing with the drive screw. Through this screw assembly, the fluid to be transported is conveyed from the suction side, where the fluid is at suction pressure, to the pressure side, where the fluid is at outlet pressure, and then the fluid is discharged from the pressure side.

[0002] These screws, whether driving screws or any one or each driven screw, are rotatably supported in the screw housing by corresponding support devices. These support devices are typically rolling bearings, housed in corresponding bearing seats within the screw housing and arranged on the respective bearing seats of each screw. The rolling bearings seal the interior of the screw housing containing the fluid to be pumped via corresponding seals. Depending on the configuration, a gearbox may also be provided, for example, in the case of a double-suction pump, to couple the screws. Sometimes, the rolling bearing side may require additional sealing via seals. During operation, if the seals wear or are otherwise damaged, leaks may occur in these sealing areas, requiring appropriate maintenance. However, maintenance is not always easy and can sometimes be quite cumbersome, such as when multiphase pumps are used underwater and inaccessible. Summary of the Invention

[0003] The problem to be solved by the present invention is to provide an improved multiphase pump.

[0004] To solve the above problems, in the multiphase pump of the above type, according to the present invention, the support device is a hydrodynamic sliding bearing, wherein the drive screw and the driven screw are accommodated via the bearing clearance, and a supply device is provided for supplying a fluid lubricating medium with a pressure higher than the suction pressure to the corresponding bearing clearance.

[0005] The multiphase pump of this invention is characterized in that its screw is supported by a hydrodynamic sliding bearing, i.e., no longer supported by a corresponding rolling bearing. To lubricate the sliding bearing, according to the invention, a liquid lubricating medium is actively introduced or injected into the bearing clearance at a correspondingly high pressure, thereby establishing hydrodynamic pressure within the bearing, which withstands hydraulic pressure and forms a seal. The pressure at which the lubricating medium is introduced is higher than the suction pressure (i.e., the pressure at which the fluid to be transported is drawn in), thus allowing the lubricating medium to establish a corresponding lubricating film within the bearing. Therefore, with this hydrodynamic sliding bearing proposed according to the invention, there is no need for sealing rings or similar separate seals for bearing sealing; instead, the hydrodynamic sliding bearing achieves wear-free support while maintaining sufficient sealing within the bearing area relative to both the inside and outside of the screw housing. This means that even multiphase pumps that are difficult or inaccessible can operate for extended periods without causing wear on the screw support area.

[0006] According to a first variation of the invention, the lubricating medium can be formed from the delivery fluid discharged from the pressure side and supplied to the sliding bearing. Under this design, the delivery fluid itself, or its liquid phase, already at a correspondingly high outlet pressure, is used to achieve bearing lubrication; that is, the fluid portion from the pressure chamber or pressure side is substantially diverted and directed to the corresponding sliding bearing, thereby being introduced into the bearing clearance. Since the fluid or liquid portion is already at an outlet pressure significantly higher than the suction pressure, no additional pump or similar device is required to introduce or inject the fluid into the bearing clearance. The actual pressure at which the fluid is injected is significantly higher than the suction pressure, and may be equal to the outlet pressure, but not necessarily. Therefore, the present invention is equivalent to providing an internally integrated lubrication at the sliding bearing level without the need for an additional lubricating medium.

[0007] In an improved embodiment of the invention, a channel structure can be provided through which fluid is guided from the pressure side to the bearing clearance. According to a specific embodiment, this channel structure can pass through the screw housing or a cover placed on the screw housing, essentially integrated into the housing side. Its advantage is that this channel structure can be implemented without the need for additional piping. Alternatively, the channel structure can also be implemented at least partially via separately laid piping. For example, channel sections can be implemented within the screw housing or within a cover placed on the screw housing, these channel sections being directly guided to their respective bearing clearances, wherein these channel sections are connected to correspondingly laid piping that leads from the pressure side to the corresponding connection points of these channel sections. The lubricating medium injected into the bearing clearance is distributed within the bearing clearance, wherein one side of the bearing clearance is typically connected to a low-pressure region (typically the suction pressure), and the other side is connected to a high-pressure region (typically the outlet pressure). At this point, the lubricating medium flows to the low-pressure region, which ultimately flows to the suction region. This suction region depends on the specific design of the multiphase pump or the arrangement of the sliding bearings. It can be located inside the screw housing within the fluid inlet area, or it can be outside the screw housing, such as in the area where the drive screw connects to the drive motor, or a similar area. Generally, fluid will not flow into the high-pressure region because the injection pressure is usually slightly lower than or at most equal to the fluid pressure in the high-pressure region.

[0008] As an alternative to the aforementioned variation where the fluid is generally guided directly from the pressure zone to the bearing location, another variation of the invention proposes that the lubricating medium is formed from a transport fluid supplied via an external supply line from a separation device and connected to a multiphase pump. The transported fluid (i.e., the multiphase mixture) is first guided by the pump to the separation device, which, in the case of underwater operation, is located on land. In this separation device, at least the liquid phase is separated from the gas phase. The liquid phase (e.g., oil or an oil-water mixture) serves as the lubricating medium and is guided back to the multiphase pump via a corresponding supply line and injected at the bearing location. For this purpose, the multiphase pump can also have an integrated channel structure, for example, constructed or integrated into a screw housing, housing cover, or similar component, and this channel structure is connected to the supply line via a suitable connecting mechanism. Within this channel structure, the externally supplied fluid is then distributed to the individual bearing locations. Alternatively, corresponding pipelines can, of course, be laid on the pump side, connecting to the external supply line, and via these pipelines, the lubricating medium can be distributed to the bearing locations. Here, the fluid itself or the fluid phase is used as the lubricating medium, thus eliminating the need for a separate lubricant. In this case, supplying fluid from the outside preferably requires a separate pump that establishes the appropriate pressure in the fluid, thereby injecting the fluid into the bearing clearance at the desired pressure, provided that the fluid itself is no longer under sufficient pressure.

[0009] However, a separate lubricating medium can also be used. In another variation of the invention, the lubricating medium can be a lubricant, particularly oil, guided from a lubricant reservoir to the sliding bearing. This lubricant reservoir is located outside the multiphase pump, i.e., it is connected to the multiphase pump via an external supply line. This lubricant reservoir, for example, contains oil to be injected into the bearing clearance. Here, a separate pump is also required to introduce the lubricant or oil into the bearing clearance at a correspondingly high injection pressure. Similarly, the multiphase pump can be provided with an integrated channel structure, i.e., a distribution channel integrated in the screw housing or housing cover, etc., through which the external supply line is connected. Alternatively, the multiphase pump can also be provided with corresponding supply lines connected to the external supply line, through which the lubricant or oil is distributed. Although a small amount of lubricant may enter the fluid to be transported separately, this amount is negligible and does not alter the properties of the fluid.

[0010] An improved embodiment of the invention proposes that each sliding bearing is formed of a bearing sleeve, wherein a lubricating medium can be supplied via a radial supply channel passing through the screw housing and leading to a radial opening in the bearing sleeve. Alternatively, the lubricating medium can also be supplied axially from a cavity defined between the screw housing and the housing cover, within which the lubricating medium is at a higher pressure. Each sliding bearing is formed of a bearing sleeve having a cylindrical outer bearing seat, by which it is accommodated in a corresponding receiving portion of the screw housing or housing cover, etc. A respective bearing clearance is formed on its inner circumference between the bearing sleeve and the through-through screw. In this case, the lubricating medium can be supplied to the bearing clearance in different ways. First, the bearing sleeve itself can be provided with at least one radial opening, which communicates with a radial supply channel leading to the opening of the bearing sleeve. The lubricating medium at increased pressure is radially supplied via this radial supply channel and injected radially into the bearing clearance through the opening, where it is distributed to both sides. As previously described, one side of the bearing clearance is at a higher outlet pressure, while the other side is at a lower intake pressure, where radially injected (e.g., injected substantially at the center of the bearing clearance length) lubricating medium is distributed to both sides within the bearing clearance. The lubricating medium flowing towards the outlet pressure side is trapped at the outlet pressure, while flowing towards the intake side, it can flow out of the bearing clearance, with continuous replenishment achieved through radial injection. Alternatively, it is conceivable that the lubricating medium could also be axially guided from a cavity where the lubricating medium is at a relatively high pressure into the bearing clearance, and then flow to the other side, i.e., the intake region or the low-pressure region. Such a cavity can be defined, for example, by a cover, in which, for example, the fluid to be delivered is at the outlet pressure, thus achieving hydraulic thrust balance and thereby providing axial support for one or both driven screws (the driven screws themselves are axially movable while the drive screw is axially fixed), i.e., establishing support pressure here to prevent excessive axial movement of these or each of the driven screws. This fluid, operating at a corresponding high pressure, also serves as a lubricating medium, which is axially forced or flows into the bearing clearance due to its high pressure, passes through the bearing clearance, enters the suction area, and is then re-delivered.

[0011] In this case, it can be envisioned that, according to the design of a multiphase pump, the drive screw and at least one driven screw are supplied with lubricating medium on one side via radial supply and on the other side via axial supply to their respective bearing clearances.

[0012] In an improved embodiment of the invention, each of the aforementioned bearing sleeves supporting the drive screw or driven screw, at least in the pressure-side region, has an annular groove disposed on its inner circumference, leading to an axially extending outlet channel that communicates with a region of the pump where the pressure is lower than the outlet pressure. This variation relates to a bearing sleeve that supports the screw end adjacent to the pressure region, i.e., the screw end adjacent to the pressure outlet of the screw housing. The bearing sleeves located in this position are supplied with lubricating medium via their respective radial openings, i.e., the lubricating medium is injected radially into the bearing clearance. From here, as described above, the lubricating medium is distributed to both sides, but the outlet pressure inside the screw housing is higher, so the lubricating medium cannot flow into the pressure region, i.e., inside the screw housing. A pressure trap is formed by the annular groove (disposed on the inner circumference of the bearing sleeve towards the sleeve end region of the pressure region) according to the invention, allowing the lubricating medium to overcome the outlet pressure and flow into the pressure trap, and then from there (i.e., the annular groove) into the axial outlet channel, and from that outlet channel into the low-pressure pump region connected to the other side, i.e., the region generally under suction pressure. For the bearing sleeve at the other end of the supporting screw, such an annular groove is not absolutely necessary, because the lubricating medium is preferably introduced axially into and flows through the bearing clearance. Nevertheless, radial injection can also be provided on this side.

[0013] Regarding the specific design of the multiphase pump, two variations can be envisioned. The multiphase pump can be a single-suction pump, having an inlet into the screw housing and an outlet out of the screw housing. Alternatively, the multiphase pump can also be a double-suction multiphase pump, where both the inlet and outlet screws have two screw sections that operate in opposite directions, these two screw sections acting together at a common outlet of the screw housing, but the screw housing has a separate inlet. Furthermore, each screw is supported by two sliding bearings in its respective screw end region.

[0014] The drive screw itself is guided out of the screw housing by one of its shaft segments, and the screw housing or a cover placed on the screw housing is sealed via a seal. The only area in the multiphase pump of this invention requiring a corresponding sealing structure is the area where the screw passes through the housing. Typically, the drive screw has a corresponding cylindrical screw area, thereby accommodating it in a corresponding through-hole in the housing cover. This area usually has a sealed throttling gap, and downstream of this area is an additional sealing ring or multiple sealing rings or a sealing box, etc. Furthermore, this area may also have a specific separate bearing layer, magnetic coupling mechanism, etc. Attached Figure Description

[0015] Further advantages and details of the present invention can be obtained by referring to the following embodiments and the accompanying drawings. (Figures:) Figure 1 A cross-sectional schematic diagram of a multiphase pump according to a first embodiment of the present invention is shown; Figure 2 It shows Figure 1 The schematic cross-sectional view of the bearing sleeve of the hydrodynamic sliding bearing of the screw in the multiphase pump is shown. Figure 3 It shows Figure 1 A partial enlarged view of the multiphase pump in the pressure side region shown; Figure 4 It shows Figure 1 A partial enlarged view of the suction side region of the multiphase pump shown; Figure 5 A cross-sectional schematic diagram of a multiphase pump in the form of a dual-suction pump according to a second embodiment of the present invention is shown; Figure 6 It shows Figure 5 A partial enlarged view of the bearing area of ​​the screw of the multiphase pump shown; and Figure 7 A cross-sectional schematic diagram of a multiphase pump according to a third embodiment of the present invention is shown. Detailed Implementation

[0016] Figure 1 A cross-sectional schematic diagram of the multiphase pump 1 of the present invention is shown. The multiphase pump 1 includes a screw housing 2, which is housed within an outer casing 3. The outer casing is provided with an inlet sleeve 4 and an outlet sleeve 5 for the fluid to be transported (e.g., an oil-gas mixture). The screw housing 2 houses a screw assembly 6, which includes a drive screw 7 and at least one driven screw 9. The drive screw is guided through the screw housing 2 and the outer casing 3 by its shaft section 8 for connection to a drive motor. Two such driven screws may also be provided. The drive screw 7 and the driven screw 9 each have a screw profile, wherein their screw profiles mesh with each other. Here, the driven screw 9 is driven by the axially fixed drive screw 7, but it is not axially fixed itself, i.e., it can move slightly axially.

[0017] The screw housing 2 is closed on one side (i.e., the pressure side D, where the fluid is at a higher outlet pressure and is drawn out) by a cover 10, which is screwed to the housing 3, and then connected to another bearing cover 11, in which the shaft segment 8 is supported by a suitable rolling bearing 12; on the other side, another cover 13 is provided, which defines a cavity 14, as will be described below, in which the fluid to be transported is at the outlet pressure in order to establish hydraulic thrust balance on this side, thereby providing axial support for the driven screw 9 which is fixed in a non-axial position.

[0018] The drive screw 7 and driven screw 9 are supported at both ends by their respective hydrodynamic sliding bearings 15, 16 and 17, 18, each formed via bearing sleeves 19, 20, 21, 22 through which the drive screw 7 and driven screw 9 pass with corresponding bearing sections. A narrow bearing clearance is formed between the inner wall of each bearing sleeve 19-22 and the outer periphery of the corresponding bearing section of the drive screw 7 and driven screw 9. Lubricating medium is injected into this bearing clearance under increased pressure to form a hydrodynamic lubricating film supporting the drive screw 7 and driven screw 9. To achieve this, a corresponding channel structure is provided, which is realized by suitable channel sections integrally formed in the screw housing 2 and, if necessary, in the outer housing 3 or cover 10. This channel structure allows the fluid or its liquid phase at the outlet pressure on the pressure side D (i.e., the outlet of the screw housing 2) to be diverted to the bearing sleeves 19 and 20, thereby supporting the two screws on the pressure side D, and to the bearing sleeves 21 and 22 on the other side, thereby supporting the two screws on the suction side S.

[0019] Figure 2 An example of a bearing sleeve is shown, with bearing sleeve 20 as an example in this figure. Further details will follow. Figure 3 The following description is provided. This implementation is the same as that of bearing sleeve 19, but the structures of the two bearing sleeves 21 and 22 may be slightly different.

[0020] The bearing sleeve 20 (as previously described, the following description also applies particularly to the bearing sleeve 19) is a hollow cylindrical component, with an external bearing housing 23 that positions the bearing sleeve 20 within a corresponding bearing housing of the screw housing 2. Axial position is defined by a limiting shoulder 24. The previously described bearing clearance is defined by an inner wall 25.

[0021] A radial opening 26 is provided, through which a corresponding channel section of the described channel structure leads to the radial opening, thereby allowing lubricating medium under appropriate pressure (in this example, the delivery fluid or its liquid phase discharged at the outlet of the screw housing 2) to be radially injected into the bearing clearance. Figure 2 As shown, the injected lubricating medium is distributed to both sides in the bearing clearance. The lubricating medium can flow unimpeded to the left because this side is adjacent to the cover 10 and connected to the area at the suction pressure pS. On the opposite side, i.e., the side facing the interior of the screw housing 2, it is at the outlet pressure pA. In order to still allow fluid to flow to this side, an annular groove 27 is constructed around the inner circumference 25, which leads to the axial outlet channel 28, and this outlet channel opens to the low-pressure side at the suction pressure pS. This creates a pressure sink on the side of each bearing sleeve facing the interior of the screw, into which fluid supplied through the opening 26 can flow.

[0022] The two bearing sleeves 21 and 22 arranged on opposite sides of the screw do not require such radial openings 26, because these two bearing sleeves are supplied with fluid in the cavity 14 along the axial direction, which is under outlet pressure as previously described, and will be explained below.

[0023] Figure 3 A partially enlarged view of the multiphase pump 1 in the pressure side region D is shown. This figure shows the bearing sleeve 19 supporting the drive screw 7 and the bearing sleeve 20 supporting the driven screw 9. The bearing sleeve 20 is marked with corresponding flow arrows. A portion of the channel structure 29 is shown in cross-section, through which pressurized fluid is supplied from the pressure side D and injected into the bearing clearance 30 via the opening 26. In this region, the channel structure 29 may, for example, radially pass through the housing 3 and / or the screw housing 2. As shown by the larger flow arrow P1, the fluid is distributed to the left and flows into the low-pressure region, also marked S for simplicity, i.e., the suction region. As shown by the smaller flow arrow P2, a portion of the fluid also flows towards the pressure side D and enters the radial groove 27 forming the pressure trap, then flows into the suction region S via the outlet channel 28. Thus, a corresponding bearing pressure can be established on this side. Of course, a hydrodynamic support is formed in the bearing clearance of the bearing sleeve 19 in the same manner.

[0024] Figure 4 A partial view of the other side of the multiphase pump 1 is shown. This figure shows the two opposite ends of the drive screw 7 and driven screw 9, supported by bearing sleeves 21 and 22 in the suction side region S. As previously mentioned, this region is closed by cover 13, thereby forming a cavity 14 under outlet pressure, which is equivalent to the presence of the pressure side D. The bearing sleeve 22 is also marked with a flow arrow in this figure. Arrow P1 also indicates the fluid flow here, but the fluid flow is entirely axial through the bearing clearance 31 here. That is, the lubricating medium (i.e., the fluid under outlet pressure) is axially introduced into the bearing clearance 31 from the right end and flows out from the left end into the suction region S, where it continues to be delivered.

[0025] In this way, a portion of the fluid or its liquid phase is discharged from the outlet of the screw housing 2 at an outlet pressure pA via an integrated channel structure and guided to each bearing position or bearing clearance, thereby achieving an integrated, wear-free hydrodynamic support.

[0026] Figure 5An embodiment of the multiphase pump 1 of the present invention as a double-suction screw pump is shown. This multiphase pump also includes a drive screw 7, whose shaft section 8 extends out of the pump housing for connection to a drive motor. Furthermore, a driven screw 9 is provided that meshes with the drive screw 7. Each of the two screws has two screw profile sections, but for each screw, these two screw profile sections rotate in opposite directions. This achieves two suction sides S located at the ends of the screw housing 2 (which is also surrounded by the outer casing 3) and a central pressure side D (where the oppositely rotating screw sections of the two screws 6 and 7 operate). The structure of this double-suction multiphase pump 1 is essentially known.

[0027] Two end caps 10 are provided here, which respectively close the screw housing 2 and screw it to the outer casing 3. Each end cap 10 is provided with an additional cap 13, which achieves axial closure of the respective end housing. Low pressures act in these corresponding cavities 32, ultimately corresponding to the suction pressure or inlet pressure. These cavities are collection chambers for collecting any leaked fluid.

[0028] Here, the ends of each screw 6 and 7 are also slidably supported by corresponding hydrodynamic sliding bearings 15, 16, 17, and 18, which are implemented in the form of corresponding bearing sleeves 19, 20, 21, and 22.

[0029] As shown by arrow P3 in the figure, the lubricating medium (preferably a fluid discharged from the pressure side D and at the outlet pressure pA) is radially supplied to the bearing gaps of the bearing sleeves 19-22 so as to form a hydrodynamic lubricating film there.

[0030] In response, Figure 6 A partially enlarged view of the bearing sleeve 19 is shown. The cover 10 is shown, and a channel section 33 of the corresponding channel structure 29 passes through the cover 10; similar channel sections 33 are also provided on the other side of the pump. The radially injected fluid (see arrow P3) then flows through the opening 26 of the bearing sleeve 19 and distributes to both sides. The reason the fluid can be distributed to both sides is that there are suction areas S, i.e., low-pressure areas, on both sides of the bearing clearance 29. The fluid flowing to the left is then conveyed via the screw assembly 4, while the fluid flowing to the right is collected in its respective cavity 32 and from there returned to the normal suction area via a return channel (not shown in detail).

[0031] It should be noted (this also applies to) Figures 1 to 4 (As shown in the design), the individual bearing sleeves 19, 20 or 21, 22 arranged on each side can have their own lubricant supply, but this is not necessarily the case. More precisely, it is also conceivable that these bearing sleeves are interconnected, so that the lubricating medium supplied through one bearing sleeve can also be supplied to the other bearing sleeve.

[0032] although Figure 5 The pump shown is a double-suction multiphase pump without a gearbox, but alternatives are also conceivable. Figure 5 The left side shown can be equipped with a gearbox instead of the cover 13 provided here, through which the drive screw 7 and the driven screw 9 are coupled. Of course, the gearbox is also covered by a pressure seal via a suitable gearbox cover.

[0033] at last, Figure 7 Another embodiment of the multiphase pump 1 of the present invention is shown, the structure of which is similar to Figure 1 The multiphase pump shown here also includes a screw housing 2 and an outer casing 3. The screw housing 2 houses a screw assembly 6, which includes a drive screw 7 and a driven screw 9. Similarly, the drive screw 7 is supported by two bearing sleeves 19 and 21, while the driven screw 9 is slidably supported by two bearing sleeves 20 and 22. For details regarding its structure and other designs, including the bearing sleeves, please refer to [reference needed]. Figure 1 Explanation.

[0034] exist Figure 1 In the design shown, providing the bearing clearance for the hydrodynamic sliding bearing is equivalent to being achieved by the multiphase pump 1 itself, i.e., a portion of the transport fluid or its liquid phase, delivered from the screw housing 2 at outlet pressure pA, is diverted and guided to the bearing clearance via the channel structure and injected into it, unlike this. Figure 7 The design shown includes an external supply of lubricating medium. Figure 7 In the schematic diagram shown, a separation device 34 is provided, which is arranged outside the multiphase pump 1. The fluid (e.g., an oil-gas mixture) delivered by the multiphase pump 1 and discharged through the outlet sleeve 5 is supplied to the separation device via the supply line 35. In the separation device 34, the mixture is separated into a liquid phase and a gas phase, wherein the liquid phase or a portion thereof is contained, for example, in a storage tank 36. Optionally, via the pump 37 shown in this figure, the fluid (i.e., the lubricating medium) from the storage tank 36 is first led out through the line 38, and then supplied to the cavity 14 via a specific supply line 39. The fluid flows axially from the cavity through the bearing clearance (e.g., the joint) between two adjacent bearing sleeves 21, 22. Figure 4 On the other hand, the fluid is guided to the bearing sleeves 19 and 20 via the supply pipeline 40, and from there is radially injected into the corresponding bearing gaps. Here, the lubricating medium is supplied from the outside, which is in turn taken from the supplied fluid, except that the fluid is obtained from the external separation device 34 as described above.

[0035] As Figure 7An alternative to the design shown can also be to supply a separate lubricating medium (e.g., oil) that is neither derived from nor separate from the fluid being transported. This lubricating medium can be an additional, separate lubricant supplied via a pump from a suitable storage tank. The basic structure of the lubricating medium supply corresponds to the combination of... Figure 7 The structure described herein is only different in that the supply line 35 is not required. In this design, a corresponding supply device with a corresponding lubricant reservoir and pump is provided to replace the separation device 34.

[0036] What all implementations have in common is that the screw support area inside the pump housing does not require a separate seal (e.g., in the form of a sealing ring), because support and sealing are achieved entirely via a hydrodynamic sliding bearing and the injected lubricating medium. Only the drive screw 7 needs to be supported in a suitable manner by its shaft section 8 and sealed relative to the screw housing 2, outer casing 3, or end cap 10 via a corresponding seal. Various known seals, such as standard seals, sealing boxes, etc., can be used for this purpose.

Claims

1. A multiphase pump with a screw pump structure, comprising a screw housing (2) having a screw assembly (6) therein, the screw assembly including a drive screw (7) and at least one driven screw (9) meshing with the drive screw, wherein the screw assembly (6) enables the pumping of a fluid from the suction side (S) where the fluid is at a suction pressure (pS) to the pressure side (D) where the fluid is at an increased outlet pressure (pA), wherein, The driving screw (7) and the driven screw (9) are rotatably supported in the screw housing (2) via support devices. Its features are, The support device is a hydrodynamic sliding bearing (15-18), wherein the drive screw (7) and the driven screw (9) are accommodated via bearing gaps (30, 31), and a supply device is provided for supplying a fluid lubricating medium with a pressure higher than the suction pressure (pS) to the corresponding bearing gaps (30, 31).

2. The multiphase pump according to claim 1, characterized in that, The lubricating medium is formed by the delivery fluid discharged from the pressure side (D) and supplied to the sliding bearing (15-18).

3. The multiphase pump according to claim 2, characterized in that, A channel structure (29) is provided to guide fluid from the pressure side (D) to the bearing clearance (30, 31) via the channel structure.

4. The multiphase pump according to claim 1, characterized in that, The lubricating medium is formed by a transport fluid supplied via an external supply line (38) from the separation device (34) and connected to the multiphase pump (1).

5. The multiphase pump according to claim 1, characterized in that, The lubricating medium is a lubricant, especially oil, that is guided from the lubricant reservoir to the sliding bearing (15-18).

6. The multiphase pump according to claim 5, characterized in that, The lubricant reservoir is connected via an external supply line to the multiphase pump (1).

7. The multiphase pump according to any one of the preceding claims, characterized in that, Each sliding bearing (15-18) is formed via a bearing sleeve (19-22), wherein the lubricating medium can be supplied via a radial supply channel (33) through a radial opening (26) through the screw housing (2) or housing cover (10) and leading to the bearing sleeve (19-22), or can be supplied axially from a cavity (14) defined between the screw housing (2) and housing cover (13), in which the lubricating medium is under the higher pressure.

8. The multiphase pump according to claim 7, characterized in that, The bearing sleeves (19-22) that support the drive screw (7) or the driven screw (9) at least in the region on the pressure side (D), or each bearing sleeve, have an annular groove (27) disposed on the inner circumference, the annular groove leading to an axially extending outlet channel (28), the outlet channel communicating with a region of the pump where the pressure is lower than the outlet pressure (pA).

9. The multiphase pump according to any one of the preceding claims, characterized in that, The multiphase pump is a single-suction pump or a double-suction pump, wherein the drive screw (7) and the driven screw (9) are each supported by two sliding bearings (15-18).

10. The multiphase pump according to any one of the preceding claims, characterized in that, The drive screw (7) is guided out of the screw housing (2) by a shaft segment (8) and the screw housing (2) or a cover (11) disposed on the screw housing (2) is sealed via a seal.

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