EP2472126B1 - Compressor with its drive unit and adjustable aerodynamic geometry - Google Patents

Description

The invention relates to centrifugal motor units and, more particularly, to integrated centrifugal compressor units in which the compressor and a compressor drive motor are mounted in a gas-tight common housing operated by the compressor.

A conventional integrated compressor unit comprises a motor means, generally consisting of an electric drive motor, and a centrifugal compressor having one or more compression stages, depending on the applications.

Each compression stage comprises a blade wheel mounted on a driven shaft driven by a rotor driven by the motor.

In certain applications, and in particular for low pressure applications, it has been proposed to use variable pitch blades to modify the work developed by the compression stage as a function of the gas flow rate. See for example WO 03/072946 A1 .

To modify the orientation of the blades, mechanical devices are used, for example by equipping the crown blades driven by worm-type devices.

A motor outside the housing is then used to actuate the mechanical device for controlling the orientation of the blades. Such an arrangement requires the provision of holes in the body of the rotating machine and the subsequent use of sealing devices. However, providing holes in the crankcase of a compressor considerably limits the range of use of the compressor which remains dedicated to low, or even medium pressures, that is to say pressures less than about 20 bar.

EP 2,006,494 A1 proposes a solution that does not require drilling but is limited in terms of pressure.

The object of the invention is therefore to overcome this drawback and to propose an integrated motor-compressor unit with a variable aerodynamic profile, that is to say capable of modifying the flow of gas within the compression stages, for a increased pressure range.

It is therefore proposed a compressor unit comprising at least one motor driving in rotation a rotor and at least one compression stage comprising a set of vane wheels mounted on a driven shaft driven in rotation by the rotor, the assembly constituted by the motor and the or each compressor being mounted in a gas-tight common housing handled by the compressor unit.

According to a general characteristic of this compressor unit, at least one of the compression stages comprises at least one aerodynamic member for adjusting the angle of incidence of the gas flow in said stage and a control motor for said mounted in the crankcase. Preferably, the adjusting member is adapted to vary the angle of the flow of gas arriving on a paddle wheel or from a paddle wheel. According to a first variant embodiment, the member is able to vary the angle of incidence of the flow of gas arriving on at least one impeller. According to another embodiment, the member is adapted to vary the angle of the flow of gas from a paddle wheel, for example to a diffuser.

Thanks to the integration of the control motor of the aerodynamic member in the housing, it eliminates the holes in the housing for the passage of the mechanical adjustment member, which thus retains a seal allowing the motor-compressor unit to work on increased pressure.

In particular, it has been found that, thanks to this arrangement, the range of use of the motor-compressor unit could be increased up to values of the order of 60 to 80 bars.

According to another characteristic, the adjusting member comprises a blade disposed along a diameter of a gas passage in the compression stage. The adjustment member may for example comprise several radial blades, each of length less than or equal to the half-diameter of the gas passage. The blades are thus able to be actuated simultaneously for example by mechanical devices such as one or more rings driven by worm type devices. Preferably, the adjustment member is configured to provide at least three different angles of incidence or departure of gas flow to a paddle wheel or from a paddle wheel.

According to yet another characteristic, the motor-compressor unit comprises between one and three compression stages, preferably a compression stage, at least one of said stages being provided with the adjustment member.

When the compressor unit comprises several compression stages, it is possible to modify the flow by means of an aerodynamic member provided for each stage.

Each control stage comprises successively, considering the circulation of the gas handled, a gas supply zone, a compression paddle wheel and a diffuser. The adjustment member may then be arranged upstream of the impeller.

Alternatively, it can be arranged in the diffuser.

Another variant consists in simultaneously installing an adjusting member upstream of the compression stage and an adjusting member in the diffuser.

According to yet another characteristic, the motor-compressor unit further comprises an electronic control unit external to the housing and connected to the control motor by power and control cables passing through the housing at the passage of sealed cables.

• la figure 1 est une vue schématique montrant l'architecture générale d'un groupe compresseur à un seul étage ;
• la figure 2 est une vue de détail du groupe compresseur de la figure 1, montrant l'organe de réglage aérodynamique ;
• la figure 3 illustre une variant de réalisation du groupe compresseur de la figure 2 ; et
• la figure 4 est une courbe montrant l'évolution de la puissance et du travail développés par le groupe compresseur en fonction du débit de gaz admis.

Other objects, features and advantages of the invention will become apparent on reading the following description, given solely by way of nonlimiting example, and with reference to the appended drawings, in which:

• the figure 1 is a schematic view showing the general architecture of a single-stage compressor unit;
• the figure 2 is a detail view of the compressor group of the figure 1 , showing the aerodynamic regulator;
• the figure 3 illustrates a variant embodiment of the compressor group of the figure 2 ; and
• the figure 4 is a curve showing the evolution of the power and the work developed by the compressor unit as a function of the flow of gas admitted.

The motor-compressor group illustrated at figure 1 essentially comprises a motor 1, constituted for example by a variable-speed electric motor driving in rotation a rotor 2, itself driving at identical speed a driven shaft 3 on which is mounted a paddle wheel 4.

As can be seen, the motor-compressor unit thus comprises a single compression stage constituted by the centrifugal impeller 4 which ensures the suction of a gas delivered from a supply line 5 to cause an increase in its pressure. and deliver it at the output 5 '.

In the exemplary embodiment shown, the rotor 2 is supported by two end bearings 6 and 7. This is also the case of the driven shaft 3 which is also supported by two end bearings 8 and 9. Thus, according to this arrangement, the rotor 2 and the driven shaft 3 are connected by a flexible coupling 10.

But it is not beyond the scope of the invention when the rotor and the driven shaft are connected by a fixed coupling. In this case, one of the bearings, such as 7 and 8, could be omitted.

However, the arrangement shown is advantageous because it greatly simplifies the assembly of the compressor unit by removing, in particular, the problems of alignment of the rotor and the driven shaft.

It is furthermore seen that the motor-compressor unit is further provided with a stop 11 for limiting the axial displacement of the driven shaft 3 under the action of the rotation of the wheel 4.

Finally, the assembly, that is to say the engine 1 and the compression stage is disposed in a gas-tight common housing 12 manipulated by the compressor. In other words, the engine 1 is here at the suction pressure of the motocompressor unit.

We have shown on the figure 2 a detailed view of the motocompressor group of the figure 1 .

In this figure, it recognizes the gas inlet 5 by which is sucked the gas to be compressed according to the arrow F, and the wheel 4 which provides the actual compression of the gas to deliver it downstream to a diffuser D in which the gas is slowed to increase its pressure and then output it.

Upstream of the wheel 4, the compressor is provided with an adjusting member, referenced 13, made in the form of a blade mounted along a diameter of a gas passage 14 extending between the inlet orifice 5 and the wheel 4. This blade is an aerodynamic element that allows to control the angle of the flow and keep it optimum over a wide range of flows. As can be seen, this blade 13 is mounted on a control rod 15 driven in rotation by a control motor 16, for example a stepping motor integrated in the motor compressor, that is to say placed inside. The motor 16 is supplied with electrical energy from outside the motor and is driven by a central unit (not shown) which causes the rotation of the motor and the subsequent orientation of the blade 13 in the passage 14 of the motor. way to move the operating curve of the motor compressor.

Of course, the power and control cables that connect the control motor and the central unit through the casing 12 at sealed passages (not shown) to the gas handled by the motor compressor so as to maintain a much greater watertightness. seals necessary for the crossing of mechanical devices according to the state of the art, when the engine is disposed outside the housing.

It will be noted that the compression stage successively comprises, between the inlet 5 and the outlet 5 ', a supply zone A, the centrifugal wheel 4, and the diffuser D. It will be noted that the aerodynamic member 13 is here placed upstream of wheel 4. It would also be possible, according to the variant illustrated in figure 3 , to arrange it at the level of the diffuser.

With reference to the figure 4 , on which is represented the evolution of the work developed by the compressor (curves a, b, c) on the one hand, and the yield (curves a ', b' and c ') on the other hand, as a function of admitted flow at the input of the motor-compressor unit, it is possible to maximize the aerodynamic efficiency of the compressor thanks to the variable setting being able to have a larger flow rate range.

In particular, with respect to the developed work, from an original position (curve a) in which the blade 13 extends along the general axis of the gas flow passage in the compressor, it is It is possible, by varying the angular position of the blade, to modify the angle of the gas flow and thus modify the flow rate for the same pressure value.

In other words, it is found that the modification of the angle of incidence of the gas flow makes it possible to translate the operating curve of the compressor and thus to adapt its operating range.

Furthermore, the engine 1 and the compression stage 3 are arranged in a same gas-tight casing 12, so that the inside of the motor-compressor unit, and in particular the engine 1 and at least the compression stage 3, are immersed in the gas handled, at the gas pressure entering via the supply line 5. The interior of the motor compressor is devoid of shaft outlet seal, because the shafts carrying the motor 1 and carrying the wheel to blades 4, and the bearings supporting them, are integrally included in the housing. The motor-compressor unit comprises only rotating joints subjected to small differences in pressure, for example of the labyrinth type. No leakage of process gas to the atmosphere can then occur, since the crankcase openings are limited to the gas supply line 5, the gas outlet line 5 ', the passages for the control cables and power supply of the motors 1 and 16, and the contour of a cover (not shown) for inserting the various members in the housing. In addition, in order to limit ventilation losses, engine 1 is subjected to the suction pressure is established at the supply line 5. A gas flow can also be organized to ensure its cooling.

A particularly advantageous application of the invention relates to gas transfer stations for which the pressure ratios between the suction and the backflow to be developed are relatively low, especially less than 2, and for which the motor-compressor units are preferably mono- storied or generally less than three storeys. Indeed, for this type of application, it is often desirable to have a relatively large flow rate range in order to be able to offer low or large flows.

But, of course, any other application in which it is desired to have a relatively large flow rate range may also be considered.

Note also that the use of an aerodynamic member for controlling the angle of incidence of the gas flow is advantageous for motor-compressor groups comprising from 1 to 3 stages of compression. However, such a member may advantageously be installed in single-stage motor-compressor units. But when using a multi-stage compressor, the aerodynamic member can be mounted either on the first compression stage or on all stages.

As indicated above, the aerodynamic member may be mounted either at the inlet of the compression vane wheel, in order to modify the angle of incidence of the gas flow handled by the blade wheel, or at the level of the diffuser in order to modify the deceleration of the gas and thus modify the operating range. According to another embodiment, it is also possible to provide an aerodynamic regulating element upstream of or at the inlet of the blade wheel or, in other words, upstream of the compression stage, and a compression member. adjustment in the diffuser.

Claims (8)

1. Motorcompressor unit capable of operating at an inlet pressure of 60 bar or higher, comprising at least one first electric motor (1) driving the rotation of a rotor (2) and at least one compression stage comprising a set of bladed impellers (4) mounted on a driven shaft (3) the rotation of which is driven by the rotor (2), the ensemble comprising the electric motor and the or each compressor being mounted in a common casing (12) that is gastight with respect to the gas handled by the compressor unit, the first motor (1) and the compression stage being arranged in the casing in such a way that the first motor (1), and at least part of a bladed impeller of the compression stage, are subjected to the same pressure of gas entering the compression stage, characterized in that at least one of the compression stages comprises at least one member (13) for regulating the angle at which the gas flows to or from a bladed impeller of a compression stage and a motor (16) for controlling the regulating means mounted in the common casing.
2. Compressor unit according to Claim 1, characterized in that the regulating member comprises at least one vane arranged across a diameter of the gas passage.
3. Compressor unit according to either of Claims 1 and 2, characterized in that it comprises between one and three compression stages, preferably one compression stage, at least one of the said stages being provided with the regulating member (13).
4. Compressor unit according to any one of Claims 1 to 3, characterized in that each compression stage comprises, in succession, in the direction in which the handled gas flows, a gas supply zone, a bladed compression impeller and a diffuser, the regulating member being arranged upstream of the impeller.
5. Compressor unit according to any one of Claims 1 to 3, characterized in that each compression stage comprises, in succession, in the direction in which the handled gas flows, a gas supply zone, a bladed compression impeller and a diffuser, the regulating member (13) being arranged in the diffuser.
6. Compressor unit according to any one of Claims 1 to 3, characterized in that each compression stage comprises in succession, in the direction in which the handled gas flows, a gas supply zone, a bladed compression impeller and a diffuser, and in that it comprises a regulating member (13) arranged upstream of the impeller and a regulating member arranged in the diffuser.
7. Compressor unit according to any one of Claims 1 to 6, characterized in that it further comprises an electronic control unit external to the casing and connected to the control motor by supply and control cables that pass through the casing at fluidtight lead-throughs.
8. Motorcompressor unit according to one of the preceding claims, configured to provide a pressure ratio lower than 2 between the intake and the delivery.

Images