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Title:
TWO-PHASE, SELF-PRIMING RADIAL TURBO PUMP
Document Type and Number:
WIPO Patent Application WO/2014/095027
Kind Code:
A1
Abstract:
A two-phase, self-priming radial turbo pump (10) comprising a connections body (12) having a suction mouth (22) and a delivery mouth (30), a channel body (14) with a volute (36), an impeller (16) having a radial blading (50) arranged revolving at the centre of said channel body (14) and a rear body (18). The impeller (16) is further provided with a peripheral blading (52) cooperating with a peripheral channel (40) with discontinuous circular extension formed in the channel body (14) and with at least a pair of supply openings (42) (44) made in the channel body (14) itself.

Inventors:
GENNARI, Francesco (Via Labirinto, 159, Brescia, I-25125, IT)
Application Number:
EP2013/003795
Publication Date:
June 26, 2014
Filing Date:
December 16, 2013
Export Citation:
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Assignee:
ARGAL S.R.L. (Via Labirinto, 159, Brescia, I-25125, IT)
International Classes:
F04D9/00; F04D9/02
Foreign References:
US2553066A
US4692092A
US3973867A
US3936240A
DE711791C
US2553066A
Attorney, Agent or Firm:
LECCE, Giovanni (Dott.Giovanni Lecci & C. S.r.l, Via Fratelli Ruffini 9, Milano, I-20123, IT)
Download PDF:
Claims:
Claims

1. A two-phase, self-priming radial turbo pump (10), comprising a connections body (12) having a suction mouth (22) and a delivery mouth (30), a rear body (18), a channel body (14) comprising a volute (36), an impeller (16) having radial blading (50) arranged revolving at the centre of said channel body (14), characterised by the fact that said impeller (16) is further provided with a separate peripheral blading (52) (from claim 2) contained in an annular support (54) with semi-circular section superimposed on said radial blading (50) which is of the centrifugal type, said radial-centrifugal blading (50) cooperating with a peripheral channel (40) with discontinuous circular extension formed in the channel body (14) and with at least a pair of supply openings (42, 44) made in the channel body (14) itself.

2. The turbo pump (10) according to claim 1, characterized by the fact that said channel body (14) consists of a hollow cylinder-shaped body open on both extremities, split internally into two sectors by means of a partition wall (34) positioned radially to said channel body (14), where in the sector facing the connections body (12) are made concentrically the one to the other an inner chamber (20") and an outer chamber (28") and in the sector facing the rear body (18) is made the volute (36), communicating in the outer extremity of the spiral with the outer chamber (28") in a tangential direction through an exit section (38) and communicating in its inner periphery with an impeller compartment (45) of cylindrical shape made in the partition part (34) and communicating in its central part with the inner chamber (20").

3. The turbo pump (10) according to claim 1, characterized by the fact that said connections body (12) comprises an inner chamber (20') communicating with the suction mouth (22), an outer chamber

(28') concentric with said inner chamber (20') and communicating with the delivery mouth (30), said connections body (12) creating, together with said channel body (14), a suction duct (20) formed by the union of the corresponding inner chambers (20'), (20"), as well as a delivery duct (28) formed by the union of the corresponding outer chambers (28'), (28") of said connections body (12) and channel body (14).

4. The turbo pump (10) according to the claims 1 and 2, characterized by the fact that said peripheral channel (40) is obtained in part along the partition wall (34) of the channel body (14) and communicates with the impeller compartment (45) wherein the impeller (16) is housed revolving, with said peripheral blading (52) facing onto said peripheral channel (40), and that said impeller compartment (45) communicates in its outer periphery with the volute (36).

5. The turbo pump (10) according to claim 4, characterized by the fact that the peripheral channel (40) has a semi-circular section and interrupts its extension for a quota corresponding to an angle between 30° and 50°, and is coaxial with respect to the section of the channel body (14).

6. The turbo pump (10) according to the claims 1 and 2, characterized by the fact that said volute (36) in its lower part is in communication with the outer chamber (28") by means of at least a supply opening (42) through the partition wall (34).

7. The turbo pump (10) according to claim 5, characterized by the fact that in the proximity of the area of interruption of the extension of the peripheral channel (40) is made at least a supply opening (44) of communication between the delivery duct (28) and the impeller compartment (45), through the partition wall (34).

8. The turbo pump (10) according to claim 3, characterized by the fact that the connections body (12) comprises a filling hole (24) and a drain hole (32) having corresponding closing caps.

9. The turbo pump (10) according to claim 1, characterized by the fact that said radial blading (50) consisting of a plurality of radial blades (50') and said peripheral blading (52), consisting of a plurality of peripheral blades (52'), are made in a single piece with the impeller (16).

10. The turbo pump (10) according to claim 1, characterized by the fact that said radial blading (50) is fixed to a discoid support (48), positioned at the centre of the impeller (16), and departs so as to reach and go beyond the periphery defined by the outer diameter of said discoid support (48) which also has means for keying to a pump shaft.

11. The turbo pump (10) according to claim 2, characterized by the fact that in said inner chamber (20") is made a support bracket (46), fluid-dynamically profiled and suitable for housing the support for the keying shaft of the impeller ( 6).

12. The turbo pump (10) according to the preceding claims, characterized by the fact that the impeller (16) and the channel body (14) are made of metal or any polymer or plastic material.

Description:
"Two-phase, self-priming radial turbo pump"

Description

The present invention refers to a two-phase, self-priming radial turbo pump.

More in particular, the present invention refers to a turbo pump or, in general, to a hydraulic turbo operating machine able to start the flow of fluid, generally liquid, in empty ducts without check valve, with a "two- phase" operation obtained thanks to the configuration of the impeller and to the conformation of the stator part of the turbo pump itself.

In the state of the art hydraulic turbo machines are known, turbo pumps of radial type, which are generally "centrifugal" and made up of a highspeed rotating part commonly called "impeller" and of a fixed stator part called "casing" wherein are obtained a spiral-shaped channel called "volute", a suction duct and a delivery duct and wherein are also housed the supports for the impeller shaft and the seals.

The impeller consists of a disc wherein is obtained a blading arranged circularly with respect to the rotation axis to form ducts diverging in a radial direction and which is keyed onto a shaft supported by bearings which revolves with respect to the pump casing.

The direction of the blade profile can be turned forwards or backwards with respect to the direction of rotation of the impeller depending on whether a greater kinetic energy or pressure component is to be applied on the fluid respectively. Generally, in centrifugal pumps, applying on the fluid a high hydraulic pressure energy at outlet is desirable. The fluid reaches the suction duct on the impeller in an axial direction and, flowing along the diverging rotating ducts, is deviated radially with respect to the axial inlet direction, moving away from the rotation axis of the impeller which by centrifugal effect transfers energy to the fluid. After receiving hydraulic pressure energy, the fluid is collected in the spiral volutes of the casing and is channelled in the delivery duct. The centrifugal effect also produces a vacuum in the suction duct which recalls other fluid and keeps the duct always full. The centrifugal pumps can also be equipped with a diffuser, made up of a fixed blading arranged between the impeller and the volute, for the purpose of improving the performance of the pump.

These machines generally operate by lifting a flow of fluid from a downstream tank to an upstream tank positioned at a greater height. Fundamental characteristics of the pump are:

the "manometric head", i.e., the energy which the pump yields to the fluid irrespective of its density;

- the flow rate, i.e., the quantity of fluid volume that flows through the pump;

- the "suction lift", i.e., the negative suction head height at which the pump is installed with respect to the suction tank.

A typical drawback of these machines occurs at start-up, when the pump is empty (full of air), when the difference in pressure produced by the impeller is in order of magnitude one thousand times below that in the presence of fluid (e.g. water) and the consequent limited pressure differential (drop) is often not enough to recall the fluid in the suction duct and therefore to "prime" the pump. To produce a difference in pressure such as to lift and suction the fluid, the pump must be "primed", i.e., when it is started, the suction duct and the inside of the casing must always be full of fluid. This condition is commonly achieved using various solutions:

by fitting a check valve (or a non-return valve) at the start of the pump suction duct;

by manually filling the pump with fluid;

- by using special construction solutions to create a siphon effect in the suction duct, so that the pump always remains full of fluid.

These types of pumps are commonly called "self-priming".

Another drawback concerns the fact of not being able to operate with high-density fluids (high specific weight), or with high vapour pressure, because to be primed they require a greater pressure differential (drop) inasmuch as they tend to decompose and develop gas in growing quantity.

Another typical drawback is that of not being able to install the pump at a suction lift above a certain limit, beyond which the pressure in the suction duct drops below the fluid vapour pressure, prompting the appearance of "cavitation". This phenomenon is harmful and undesirable in a hydraulic machine, inasmuch as it wears and deteriorates the mechanical parts and drastically reduces performance.

US 2 553 066 describes a two phase, self-priming radial pump (10), which envisages the combination of two separate devices (centrifugal pump and peripheral pump) aligned on a single axis and connected with passages system which, aided in their action by a valve, reconstruct the respective suction and delivery mouths.

Object of the present invention is to overcome the drawbacks complained of above.

More in particular, the main object of the present invention is to provide a two phase, self-priming radial turbo pump, of extremely simple construction which can be started with empty ducts and without the aid of a non-return valve, and without the aid of any mechanical device or of additional hydraulic circuits outside the pump.

This object is achieved thanks to the combined and selective action of two types of blading (radial-peripheral and radial-centrifugal respectively) arranged on a single rotating element, which act alternately on gaseous and liquid fluid compounds, enabling the pump to be started with liquid- free ducts.

A consequent advantage of the invention is that of providing a two- phase, self-priming radial turbo pump able to operate with higher suction lifts and reduced fluid priming time in the suction duct compared to traditional self-priming centrifugal pumps.

Another consequent advantage of the invention is that of providing a two-phase, self-priming radial turbo pump suitable for priming both high-density fluids and high vapour pressure fluids.

A further object of the invention is to place at the disposal of users a two-phase, self-priming radial turbo pump able to ensure a high level of resistance and reliability over time, and such as to be easily and cheaply made. These and other objects and advantages still are achieved by the two- phase, self-priming radial turbo pump forming the subject of the present invention in agreement with the main claim.

The construction and functional characteristics of the two-phase, self- priming radial turbo pump of the present invention can be better understood from the detailed description that follows, wherein reference is made to the attached drawing tables which represent one of its preferred and non-limitative embodiments and wherein:

- the figure 1 is an exploded axonometric representation of the turbo pump forming the subject of the invention;

the figure 2 is a schematic axonometric representation of the partially sectioned turbo pump;

- the figures 3a and 3b are schematic representations of a perspective view without wall and of a section view of the turbo pump;

the figures 4a and 4b are schematic axonometric representations of the impeller;

the figures 5a and 5b are schematic representations of a section view and a perspective view respectively of the impeller;

- the figures 6a and 6b are schematic axonometric representations of the channel body of the casing of the same turbo pump;

the figures 7a and 7b are schematic representations of a section view and of a perspective view respectively of the channel body; the figure 8 is a schematic representation of the flow pattern of the fluids during the priming phase, viewed in axial direction with respect to the rotation axis of the impeller 16;

- the figure 9 is a schematic representation of the flow pattern of fluids during the pumping phase, viewed in axial direction with respect to the rotation axis of the impeller 16.

With initial reference to the figures from 1 to 3b, the two-phase, self- priming radial turbo pump of the present invention, generally indicated by 10 and represented by way of example in the hydraulic part only without the driving part, consists, in its more general form, of a connections body 12, a channel body 14, an impeller 16 and a rear body 18. Given that the turbo pump 10 is self-priming, it must be installed in such a way as to allow the fluid to deposit inside it in a position substantially opposite with respect to the delivery mouth 30, which in the example shown in the illustrations is orientated vertically, i.e., in the direction of the arrow marked by the letter "z".

The connections body 12 shown in the figures from 1 to 3b has a general axial-symmetric shape, open and flanged at one extremity with two concentric chambers, one inner and one outer, not communicating with each other and marked by the reference numbers 20' and 28' in the figure 3b. The inner chamber 20', open towards the flanged extremity, communicates outwards on its opposite extremity with a cylinder-shaped perforated protuberance realizing a suction mouth 22, orientated in the direction opposite to the arrow "y", which permits connection with a suction manifold. In the proximity of said suction mouth 22 a manual filling hole 24 is made, advantageously threaded and closed by a corresponding cap not represented, exiting from the connections body 12 and also orientated in the direction of the arrow "z". The outer chamber 28' communicates outwards with a cylinder-shaped perforated protuberance, realizing a delivery mouth 30, exiting from the connections body 12 in the direction of said arrow "z"; the delivery mouth 30 permits connection with a delivery manifold.

Said outer chamber 28' has a fluid drain hole 32, advantageously threaded and closed by a corresponding cap not represented, exiting from the extremity of the connections body 12 in the direction of the arrow marked by the letter "y".

In the figures from 1 to 3b and from 6a to 7b, is schematized the channel body 14, consisting of a hollow cylinder-shaped body, internally split up into two sectors through a partition wall 34 positioned radially; the channel body 14 is open on both the extremities and is further advantageously flanged on both said extremities. In the coupling part to the connections body 12, the channel body 14 has two concentric chambers, inner and outer, marked by the reference numbers 20" and 28" in the figures 3b, 6a, 6b and 7a respectively and corresponding to the chambers 20' and 28' of the connections body 12 according to the same figure 3b. With the coupling of the channel body 14 to the connections body 12, the inner chamber 20" in correspondence to the inner chamber 20' identifies the suction duct 20 of the turbo pump, while the outer chamber 28" in correspondence to the outer chamber 28' identifies the delivery duct 28 of the turbo pump. Said connections are made easier to assemble by specific known projecting parts and grooves which make them easier to centre and which can advantageously accommodate sealing gaskets. In the coupling part of the channel body 14 to the rear body 18 a volute 36 is obtained, made up of a spiral-shaped channel, generally right-handed, which extends in a radial direction for an angle of circumference of about 315°, from the centre towards the outside of the channel body 14. In the central part of the channel body 14 is obtained, inside the partition wall 34, an impeller compartment 45 of circular shape suitable for accommodating the impeller 16. Said impeller compartment 45, shown in the figures 6a, 7a and 7b, communicates in the central part of the channel body 14 with the inner chamber 20" and in the peripheral part with the volute 36 and also communicates with the outer chamber 28" through one or more fluid-dynamically shaped supply openings 44. Said volute 36 communicates with the impeller compartment 45 through the whole inner circumference and increases in section from the inside towards the outside of the section of the body 14; the same volute 36 is separated from the outer chamber 28", in the direction opposite to the arrow "y" in figure 1, by the partition wall 34 and terminates with an opening section 38, which communicates with the outer chamber 28" in a tangential direction to the channel body 14 in its higher part on the partition wall 34. The volute 36, furthermore, also communicates with the outer chamber 28" in its lower part, by means of a supply opening 42 which crosses the partition wall 34. In the peripheral part of the impeller compartment 45, in the proximity of the volute 36, is obtained a peripheral channel 40 with discontinuous circular extension and with semi-circular section, which also extends in part along the partition wall 34; the peripheral channel 40 is interrupted in the lower part of the body in the opposite direction to that of the arrow "z", for a quota corresponding to an angle between 30° and 50°, preferably 45°, and is coaxial with respect to the section of the channel body 14.

The part of the channel body 14 of the turbo pump 10 which couples to the rear body 18, made up of a closing plate for the volute 36 of the channel body 14 itself, communicates with the chamber 28" in the direction of the arrow "y" through one or more fluid supply openings 42, placed in correspondence to the lower part of the volute 36, in the direction opposite to the arrow "z". The same part of the channel body 14 communicates with said outer chamber 28" by means of at least one fluid supply opening 44 in the proximity of the peripheral channel 40 in its area of interruption.

Inside the inner chamber 20" is advantageously fixed a supporting bracket 46, fluid-dynamically profiled, to support the pump shaft on which the impeller 16 is keyed.

With reference to the figures from 1 to 5b the impeller, indicated by 16, consists of a discoid support 48, having at centre suitable means of keying (not shown) to a pump shaft; on the front of said discoid support 48 turned towards the channel body 14 is obtained a conventional radial blading 50 with centrifugal action, which departs from the central area of the discoid support 48 itself until it reaches and passes beyond its periphery defined by its outer diameter. The extremity portions of the single blades indicated by 50' in the figures 4a and 4b of said radial blading 50, are connected to an annular support 54 with a preferably concave profile, on which is obtained and over which is superimposed a continuous peripheral blading 52, arranged radially inside said annular support 54. The peripheral blading 52 consists of a plurality of small blades 52', part of which made in a single body with respective blades 50' of the radial blading 50. Generally speaking, the assembly made up of the discoid support 48, of the blades 50', 52' and of the annular support 54 form a single block defining the impeller 16.

A particular characteristic of the peripheral blading 52 of the impeller 16 is to place at disposal, in the interruption area of the channel 49 of the channel body 14, an air-liquid mix for the centrifugal blading 50 which ensures its expulsion, as will be illustrated more in detail by reference to Fig. 8 "Air-liquid mix during expulsion".

The rear body 18, shown in particular in the figures 1,2 and 3b, consists of a suitably flanged plate which closes the volute 36 of the channel body 14 at the rear extremity, in the direction of the arrow "y", splitting the hydraulic part of the turbo pump 10 of the present invention up from the driving part not shown. Said rear body 18 has at centre a suitable housing for accommodating the support and the seal of the pump shaft, onto which is also keyed the impeller 16.

From the description of the parts making up the two-phase, self-priming radial turbo pump forming the subject of the invention, the operation of same can be deduced as described below.

In the machine stopped condition, the suction ducts 20 and delivery ducts 28 of the turbo pump 10 contain a volume of fluid useful for the formation of the air/ fluid mix in priming phase. This fluid volume, preliminarily introduced only once before the start of the turbo pump 10, remains deposited after operation inside the turbo pump itself by means of the layout of the suction mouth 22 and the delivery mouth 30 and of the suction duct 20 and delivery duct 28, which create a siphon effect.

During the initial priming phase or peripheral phase, in agreement with the figure 8, the centrifugal action of the blades 50' of the radial blading 50 is deprimed from the air input through the suction duct, indicated by the reference number 20 in figure 8, which prevents creating a vacuum such as to recall the fluid. In this phase of inactivity of the radial blading 50, the peripheral blading 54, by rotating in correspondence to the peripheral channel 40, interacts with it, creating a nebulized mix of air from the suction duct 20 and of filling fluid, deposited in the body of the turbo pump 10 (self primed), which is generally the same fluid to be pumped. In the section wherein the peripheral channel 40 is interrupted, the reference is now to the figures 7a, 7b and 8, the air/ fluid mix exits from the channel 40 and is prompted to abandon the impeller compartment 45 by the impeller 16 itself, which turns inside it, and is then collected in the volute 36. At the end of the spiral of the volute 36, the nebulized air/ fluid mix is transferred by centrifugal action into the delivery duct 28 through the opening 38 where, by effect of the gradual increase in volume of the chambers wherein it circulates, the speed drops, permitting the liquid fluid to separate from the air. The air is expelled through the delivery mouth 30, while the slowed-down fluid re- circulates through the supply opening 42 in the volute 36 and one or more supply openings 44 which communicate with the impeller compartment 45, in the interruption section of the peripheral channel 40. This fluid, which returns into the suction duct 20 and delivery duct 28, helps form new air/ fluid mix which gradually envelops a further quantity of air from the suction mouth 22 expelling it, according to the cycle described above, from the delivery mouth 30. The expelled air cannot return into the suction duct 20 due to the pressure resistance caused by the nebulized mix and can only exit from the delivery duct 28. To each volume of air expelled from the delivery duct 28 corresponds a vacuum at the suction mouth 22 with the consequent raising of the same volume of liquid in the suction duct 20, which is thus recalled inside the turbo pump 10.

Once all the air has been used up, the recalled liquid completely invades the entire suction duct 20, the peripheral phase is deactivated and the centrifugal phase is primed, in agreement with the figure 9, inasmuch as no further pressure difference is created at the extremities of the supply opening 42, between the volute 36 and the delivery duct 28 and of the supply opening 44, between the impeller compartment 45 and the delivery duct 28 itself. The complete expulsion of all the air prevents the further formation of air/ fluid mix in the peripheral channel 40 by interaction with the peripheral blading 52 with said peripheral channel itself inside which only liquid fluid circulates. The flow of fluid follows the spiral path of the volute 36 by centrifugal effect and abandons that of the peripheral recirculation. The part of the fluid that remains "trapped" between the peripheral blading 52 and the annular support 54, only acts as "bearing" in pressure, cancelling any contribution to the pumping of the peripheral blading 52 of the impeller 16.

This two-phase operation of the turbo pump 10 is particularly advantageous with respect to traditional hydraulic pumps and permits achieving the following results:

- a high suction lift and reduced priming times for fluids similar to water;

- the possibility of priming high-density fluids;

the possibility of priming fluids with high vapour pressure.

The turbo pump 10, as described above, is able to operate advantageously during the initial fluid priming transitory phase and during the subsequent pumping phase. The benefits listed below are obtained:

- by means of the configuration of the impeller 16 on which are made, on the same body, not only a radial blading 50 with traditional type centrifugal effect, but also a peripheral blading 52;

- by means of the conformation of the stator part made up of the channel body 14, on which are made a peripheral channel 40 arranged on the plane parallel to the rotation plane of the impeller 16;

- by means of the impeller compartment 45 which, besides communicating with the suction duct 20 and the volute 36, communicates with the delivery duct 28 by means of at least one supply opening 44; by means of the volute 36 which, besides communicating with the delivery duct 28 through the opening 38, also communicates with the same delivery duct 28 through the supply opening 42.

Although the invention has been described above with special reference to one of its embodiments, provided by way of example and in non- limitative way, numerous modifications and variations will appear evident to an expert in the sector in the light of the description provided above.