JPH0538400U - Gas-liquid two-phase pump - Google Patents

Abstract

(57) [Summary] [Purpose] The gas phase staying on the inlet boss side of the main impeller is extracted to enable pumping even with a high void ratio. [Structure] A Barsuke type impeller having radial blades is adopted as a main impeller 1, and a through hole 3 is formed in a boss side of a main plate 2 thereof. The main impeller 1 is provided in the casing 6 at the rear stage of the through hole 3.
An axial flow impeller 7 is provided coaxially with. A guide vane 8 and a gas phase discharge pipe 9 are provided on the downstream side of the axial flow impeller 7, and a pocket 10 is provided on the circumference of the gas phase discharge pipe 9. The pocket 10
Is connected to the suction side of the main impeller 1 via a return pipe 11. The liquid phase circulates from the pocket 10 through the return conduit 11 to the main impeller suction side, and only the gas phase is discharged from the gas phase discharge pipe 9.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gas-liquid two-phase pump that conveys a gas-liquid two-phase.

[0002]

[Prior Art]

 With a conventional centrifugal or mixed flow pump, pumping is impossible when the gas phase reaches 15 to 20% by volume, and pumping is impossible even with a Barsuke type impeller having radial blades when the gas phase is about 50%. Becomes

[0003]

[Problems to be solved by the device]

 Currently, when a liquid from an offshore oilfield is transported, the gas phase may reach 90% or more, and even in such a case, a gas-liquid two-phase pump capable of a solution is required. However, in the conventional pump, when the void ratio increased, the gas phase gathered on the inlet boss side of the impeller and accumulated in a ring shape, choking the flow path and making it impossible to pump.

The present invention has been made in order to solve the problems of the prior art as described above, and the gas phase staying on the inlet boss side of the main bladed wheel is extracted to enable pumping even with a high void ratio. An object is to provide a gas-liquid two-phase pump.

[0005]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, in a gas-liquid two-phase pump according to the present invention, a main impeller is a ball-skew type impeller, a through hole is provided on a boss side of a main plate of the main impeller, and the through hole is formed. An axial flow impeller is attached to the rear stage of the hole, and a pocket is provided in the gas phase discharge pipe in the downstream of the axial flow impeller, and the pocket and the suction side of the main impeller are connected by a return pipe line. Become .

[0006]

[Action]

 According to the above means, when the void ratio is low (α <0.2), the gas-liquid two-phase is mainly discharged by the main impeller, but there is a through hole in the main plate, so part of it is in the downstream axial flow. It also flows into the impeller. In this case, the liquid level in the vapor-phase discharge conduit rises to the head created by the main impeller (stops at that position), but part of it returns to the suction side of the main impeller from the return conduit.

On the other hand, when the main impeller has a high void fraction such that the main impeller cannot be pumped, the gas phase stays in a ring shape on the inlet boss side of the impeller. This gas phase is extracted from the through hole of the main plate of the main impeller by the axial impeller of the latter stage. In the case of this high void fraction, in the axial flow impeller, the liquid phase gathers on the impeller tip side and flows in an annular shape, but the discharge pipe line has a pocket connected to the main vane wheel suction side. Therefore, the liquid phase circulates from here to the suction side through the return line, and only the gas phase is discharged from the discharge pipe.

[0008]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of a gas-liquid two-phase pump according to the present embodiment, and FIG. 2 is a view showing a flow in an axial flow impeller that changes depending on a void ratio.

In FIG. 1, a Barsuke type impeller having radial blades is adopted as a main impeller 1, and a plurality of large through holes 3 are formed on a boss side of a main plate 2 thereof. The main impeller 1 is fixed to a main shaft 4, and the main shaft 4 is supported by bearings 5. Furthermore, an axial flow impeller 7 is provided in the casing 6 at the latter stage of the through hole 3 coaxially with the main impeller 1 (may be a concentric biaxial shaft for increasing the rotation speed in some cases). There is. When the exhaust head is high, the axial flow impeller 7 may be provided in multiple stages.

A guide vane 8 and a vapor-phase discharge pipe 9 are provided on the downstream side of the axial-flow impeller 7, and the guide vane 8 is on the circumference of the vapor-phase discharge pipe 9. A pocket 10 is provided on the exit side of the. The pocket 10 is connected to the suction side of the main vane wheel 1 via a return pipe 11. Further, a wear ring seal 12 is provided between the main plate 2 and the casing 6 so that a large amount of pumped liquid of the main impeller 1 does not flow into the axial flow impeller 7. Reference numeral 13 indicates a suction pipe, and 14 indicates a discharge pipe.

In the above structure, the gas-liquid two-phase fluid flows in through the suction pipe 13, is pressurized by the main impeller 1, and flows out through the discharge pipe 14. In the case of a high void ratio, the gas phase staying on the boss side of the main plate 2 of the main impeller 1 passes through the through holes 3 by the axial flow impeller 7 through the guide vanes 8 and is discharged from the gas phase discharge pipe 9. At this time, the liquid phase flows in an annular shape on the impeller tip side as shown in FIG. There is a pocket 10 on the outlet side of the guide vane 8, and the liquid phase flows from the pocket 10 through the return pipe 11 to the suction side of the main impeller 1. In this way, the gas-liquid is separated into two phases and conveyed.

In FIG. 2, A indicates a high void rate, B indicates a medium void rate, and C indicates a low void rate, respectively, and the outside is a liquid phase. Further, D represents the inner diameter of the vapor phase discharge pipe 9, and h represents the liquid level in the vapor phase discharge pipe 9, and the liquid can be pumped when h> 0.2D.

[0013]

[Effect of the device]

 As described above, according to the gas-liquid two-phase pump of the present invention, the main impeller is the Barsuke type impeller, the main plate of the main impeller is provided with the through hole on the boss side, and the through hole A structure in which a coaxial axial flow impeller is attached to the latter stage, and a pocket is provided in a gas phase discharge pipe in the downstream of the axial flow impeller, and the pocket and the suction side of the main impeller are connected by a return pipe line. As a result, it becomes possible to convey gas-liquid two-phase with a high void ratio, which was impossible with conventional pumps. That is, when the void ratio is high, the gas phase stays on the side of the main impeller boss, and the flow path is choked, which makes it impossible to pump the liquid. A through hole is provided in the main plate so that air can be extracted and discharged by the axial impeller at the latter stage, and the fact that the liquid phase flows in an annular shape outside the pipe line is used to provide a pocket in the gas phase discharge pipe. By finally circulating the gas to the suction side of the main impeller via the return pipe, the required pump can finally achieve the required gas-liquid separation.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of main parts showing a gas-liquid two-phase pump according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flow in an axial flow impeller that changes depending on a void ratio.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main impeller 2 Main plate 3 Through hole 4 Main shaft 5 Bearing 6 Casing 7 Axial flow impeller 8 Guide blade 9 Gas phase discharge pipe 10 Pocket 11 Return pipe line 12 Wear ring seal 13 Suction pipe 14 Discharge pipe

Claims (1)

[Scope of utility model registration request] 1. A Barsuke type impeller is used as a main impeller, a through hole is provided on a boss side of a main plate of the main impeller, and an axial flow impeller is attached to a stage subsequent to the through hole, and the axial flow impeller is provided. A gas-liquid two-phase pump, characterized in that a pocket is provided in the gas-phase discharge pipe in the downstream side, and the pocket and the suction side of the main impeller are connected by a return line.