JP3346701B2 - Fluid machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid machine suitable for pumping a fluid in which a gas phase and a liquid phase are mixed, for example, when pumping crude oil from an offshore oil well.

[0002]

2. Description of the Related Art For example, oil and gas are simultaneously ejected into crude oil ejected from an offshore oil well, so that transport by ordinary pumps is not easy. Similarly, it is necessary to treat mixed air in an emergency drainage pump for coping with a sudden rise in the river during a heavy rain.

In handling such a gas-liquid multiphase flow, in order to increase the pressure and transport without separating or extracting the gas phase and the liquid phase, the bubbles in the gas phase are made as small as possible to reduce Two measures are required: homogeneous mixing in the phase portion, and suppression of bubbles remaining in the pump to prevent it from expanding.

[0004] In a conventional pump for a gas-liquid multiphase flow, techniques for homogeneously mixing a gas phase and a liquid phase include:
The front and rear impellers rotate in opposite directions to crush the bubbles flowing in the pump and break them down (counter-rotating impellers or contra-rotating pumps) or increase the number of impeller blades. Multi-wing type with increased bubble crushing action,
Multi-stage cascade arrangement with multiple stages of impellers, guide diffusers, etc., in which a gas-liquid mixer (mixer) is arranged upstream of the pump for homogeneous mixing of gaseous and liquid phases (Japanese Patent Publication 62-5)
02277).

On the other hand, techniques for suppressing the retention of air bubbles (gas phase) in a pump mainly include an impeller in which air bubbles easily accumulate, in which the impeller blades are shortened to limit the stagnation region, (See Japanese Patent Application Laid-Open No. 61-210298), the shroud of the impeller is removed and the impeller blade is opened to suppress the stagnation area by the action of leakage flow at the tip of the impeller blade. is there.

[0006]

However, in the above-mentioned conventional techniques, the impeller and the guide diffuser are each designed on the assumption of a single-phase liquid flow. Therefore, the homogeneous mixing of the gaseous phase and the liquid phase depends exclusively on the shearing action of the blade leading edge of the impeller and / or the interference action between the rotor blades of the impeller and the stator vanes of the guide diffuser. The device itself was designed on the premise of a liquid single-phase flow, and did not always consider the application of a multi-phase flow as a flow path.

According to the present invention, in a pump for a gas-liquid multi-phase flow, the retention of bubbles in the gas phase in the pump, that is, the separation of the liquid phase from the gas phase degrades the performance of pressurizing and transporting the gas-liquid multiphase flow. In view of the above factors, the bubbles flowing in the pump are made finer, and the pressure is increased and / or
Alternatively, it is intended to improve the pressure / transport performance of the gas-liquid multiphase flow of the pump.

[0008]

The present invention SUMMARY OF] has been made in view of the above circumstances, the invention of claim 1 provides a fluid machine for pumping by the rotation of the impeller fluid <br/> The blades that make up the impeller have a cross section that includes the axis of rotation.
The front edge is flat-headed, and becomes thinner toward the rear end
It is a fluid machine characterized by being formed as follows. Flat head is a plane whose leading edge is almost perpendicular to the flow
With a finger that has the widest front edge.
You.

Also, in a fluid machine for pumping a gas-liquid multiphase flow by rotation of an impeller , a leading edge of a blade of the impeller is provided.
Or even if continuous irregularities are provided on at least one of the trailing edges
Good. The shape of the unevenness is suitable for sawtooth, sine curve, rectangular wave, etc.
The pitch and depth also depend on the usage of the pump.
I can decide.

According to a second aspect of the present invention, in a fluid machine for pumping a fluid by rotation of an impeller, a guide diffuser for increasing the pressure of the fluid is provided, and a pump flow path in a portion between the impeller and the guide diffuser is provided. A fluid machine having a step formed on an inner surface. A multistage configuration in which an impeller is further provided at the subsequent stage of the guide diffuser may be employed.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Figure 1 is the calling of definitive to axial pump
This is a reference example of the present invention. That is, a main shaft 2 connected to a drive source is provided in a cylindrical casing 1, and a plurality of blades 4 are attached to a boss portion 3 of the main shaft 2 at an angle to a surface orthogonal to the shaft to form an impeller 5. I have. Saw-like irregularities 6 are formed on the front and rear edges of each blade 4 of the impeller 5, respectively. The pitch and depth of the irregularities 6 are determined according to the properties of the fluid to be handled, the impeller diameter, the rotation speed, the performance to be exhibited by the pump, and the like.

In the pump having such a configuration, as shown in FIG. 2, the front and rear edges of the impeller are formed by the serrations 6 provided on the leading edge 4a and the trailing edge 4b of the blade 4, as shown in FIG. A very strong three-dimensional vortex flow field is created in which the swirling directions are opposite to each other and form a pair. Thereby, in addition to the shear force effect in the strong shear flow layer at the leading edge of the impeller, the crushing / crushing action of the bubbles is obtained by the strong shear force effect generated by the vortex flow field. Accordingly, a uniform gas-liquid mixed fluid in which fine gas is dispersed in the liquid is formed, and the fluid can be pumped in a stable state.

Although the above-mentioned reference example has been described as applied to an axial flow pump, it can also be applied to a mixed flow pump or an open type centrifugal pump. In the above description, an example in which the present invention is applied to a single-stage pump is shown, but the present invention can be applied to a multi-stage pump. Further, in the above description, the concavities and convexities are provided on both the front and rear edges, but either one may be provided or the concavities and convexities may be provided partially.

[0014] Figure 3 shows a first embodiment of the present invention, which also describes an axial flow pump as an example. The blade 4 of the impeller 5 has a flat front end portion 4a in its cross section, and is gradually thinner toward the rear edge portion 4b. With this configuration, due to the orifice restricting effect in the impeller annular flow path formed in the casing,
A layer of strong shear flow and an associated vortex flow field are formed near the leading edge wing wall surface, and the crushing and crushing action of the bubbles is obtained by the combined strong shear force effect.

FIG. 4 shows a second embodiment of the present invention, in which a guide diffuser 7 is provided at a stage subsequent to a first stage impeller 5a, and a second stage impeller 5b is arranged at a stage subsequent thereto.
Is a multi-stage pump. The boss 3 of each of the impellers 5a and 5b has a tapered shape that spreads downstream as shown in the figure, while the boss 8 of the guide diffuser 7 has an inverse taper. And the first stage impeller 5
The front end of the boss 3a is set to have a larger diameter than the main shaft 2, and a step 9 having a large diameter on the downstream side is formed here. Further, the front end of the boss of the guide diffuser 7 is set to be larger in diameter than the rear end of the boss 3 of the first stage impeller, and the boss 3 of the second stage impeller is set.
Has a larger diameter than the rear end of the boss 8 of the guide diffuser 7, so that a step 9 having a large diameter on the downstream side is also formed here.

In the pump configured as described above,
A strong shear flow layer is formed on the flow path wall surface immediately after the step 9 due to the orifice restricting effect, and a vortex flow field formed accompanying the strong shear flow effect produces a strong shear force effect to obtain the crushing / crushing action of bubbles. Can be

[0017]

As described above, large air bubbles which flow into the impeller due to continuous irregularities formed on at least one of the leading edge and the trailing edge of the blade of the impeller and cause a reduction in pump performance. The group can be crushed / crushed and refined to improve the gas-liquid multiphase flow transport performance in the pump.

According to the first aspect of the present invention, the blade constituting the impeller is formed such that the front edge is flat-headed in a cross section including the rotation axis, and becomes thinner toward the rear end. Large bubbles that flow into the impeller and reduce the pump performance can be crushed, crushed, and refined, and the gas-liquid multiphase flow transport performance of the pump can be improved.

According to the second aspect of the present invention, large bubbles which flow in the pump flow path and cause a reduction in pump performance due to the step formed on the inner wall surface of the pump flow path having the guide diffuser for increasing the pressure of the fluid. The group can be crushed / crushed and refined, and the gas-liquid multiphase flow transport performance by the pump can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a reference example of the present invention.

FIG. 2 is an enlarged view showing a main part of FIG. 1;

FIG. 3 is a diagram schematically showing a configuration of a first embodiment of the present invention.

FIG. 4 is a diagram schematically showing a configuration of a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 casing 2 main shaft 3 boss 4 blade 4a leading edge 4b trailing edge 5, 5a, 5b impeller 6 irregularities 7 guide diffuser 8 boss 9 step

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F04D 29/24

Claims (2)

(57) [Claims] 1. A fluid machine for pumping a fluid by rotation of an impeller, wherein a blade constituting the impeller has a flat front edge in a cross section including a rotation axis, and becomes thinner toward a rear end. A fluid machine characterized by being formed in. 2. A fluid machine for pumping fluid by rotation of an impeller, wherein a guide diffuser for increasing the pressure of the fluid is provided, and a step is formed on an inner surface of a pump flow path in a portion between the impeller and the guide diffuser. A fluid machine characterized by the above.