EP2825776B1 - Rotary compressor provided with at least one side channel - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to the field of volumetric compressors and more specifically volumetric compressors known as peripheral or regenerative compressors. These machines are intended to compress a fluid, in particular a gas, between an inlet opening (or inlet) and an outlet opening (or outlet) in the manner of a dynamic compressor.

Many achievements have been known for many years but this technology appears promising because decisive improvements can be made.

STATE OF THE PRIOR ART

The oldest volumetric compressors appear in the 1950s and include a series of vanes or vanes attached to the end of a wheel-shaped rotor, which rotate in an annular channel where they are mounted with minimal clearance. These machines, unlike vane compressors, do not require lubrication and friction is reduced. However leaks result from these assemblies which furthermore do not offer good yields.

The performances of the peripheral compressors are between those of the vane compressors and those of the centrifugal compressors. The aerodynamics of the peripheral compressors are therefore based on the rotation of vanes in an annular channel. As a result, the movement imparted to the fluid is a relatively complex helical movement, which induces compression comparable to that of a multi-stage compressor. A high compression ratio and low rotation speeds are the technical characteristics of this type of compressor.

In the 1970s the shape of the volumetric compressor blades was changed as well as that of the annular channel so as to improve the centrifugal effect. In particular, the blades have evolved to larger dimensions and more elaborate forms.

An improvement consisted in providing curved blades. The patent US 3,973,865 illustrates an example of a compressor of this type whose blades have a shape, a material and dimensions intended to reduce the noise created at the entrance and exit of the peripheral channel. The efficiency of this type of compressor is of the order of 40% for a flow rate of approximately 1000m3 / h, and with a compression ratio of 1.3 per stage. GB 2,036,870 describes the elements of the preamble of claim 1.

A further improvement consisted in setting up an annular element called the central core in an annular or toroidal channel disposed laterally to the disc-shaped rotor. The flow in the annular channel therefore becomes three-dimensional. The figure 1 schematically illustrates this type of machine that can be likened to a centrifugal compressor with partial and multi-stage injection. Yields of the order of 50% are obtained with this type of machine, having a flow rate of 4000 m3 / h and a compression ratio of about 1.6. The rotor speeds are relatively low, of the order of 100m / s which reduces the wear problems of the parts. The low speeds of the rotor make it possible to use any type of metal for the blades. However, this technological evolution did not have the expected commercial success because the value of the energy efficiency was still insufficient to compete with the best performing centrifugal machines; Applications were limited to cases where mechanical simplicity was favored

We also know compressors as illustrated on the figure 2 , improvements to those of the figure 1 because with several side channels. These compressors may comprise two so-called lateral channels because each is arranged symmetrically on either side of the main plane of the rotor. The figure 2 shows an example with three channels peripherals: two lateral and one radial. Each of the thus arranged channels has its own inlet and outlet ports. If the output of the first channel is associated with the input of a second channel, the fluid is compressed twice so that the flow rate being that of a single channel compressor, the compression will be doubled.

In the case where the compressor has two side channels disposed on either side of the plane of the rotor, the two inputs and the two fluid outlets are twinned, which doubles the flow of the compressor.

Numerical simulations of such three-dimensional flows of fluids have proved unclear and numerically limited. Any attempt at simplification by single or two-dimensional simulations is inherently insufficient because the different flows (input, output, recirculation, tangential, circular) have comparable proportions while each having significant and hierarchically variable influences for all operating regimes. .

SUMMARY OF THE INVENTION

The invention aims to overcome the drawbacks of the state of the art and in particular to provide a side channel compressor of simple design, whose performance is improved; leaks are also greatly diminished and are not very significant.

For this purpose, a rotary compressor according to claim 1 is proposed.

According to a first aspect of the invention, the respective configurations and shapes of the rotors, the peripheral channels and the series of blades are such that the ratio A / R2 is between 6% and 16%. In addition, the compressor according to the invention may comprise a third series of vanes disposed on an opposite lateral face of said rotor and within a given specific channel.

This characteristic dimensioning makes it possible in particular to optimize the compression of the fluid in the compressor. The blades accelerate the fluid in a movement both tangential to the rotor and perpendicular to this tangential motion. The fluid flow induces multiple fluid passages between the blades over several turns, resulting in improved compression ratio and relatively low rotational speeds.

In addition, said at least one first series of blades has a dimension h measured parallel to or perpendicular to the axis XX of rotation of the rotor, said dimension h being such that the ratio h / R is between 5% and 15%.

This feature aims to improve the performance of the compressor.

Advantageously said housing of said at least one peripheral channel and / or said static core has internal reliefs intended to modify the direction of the fluid flowing inside said peripheral channel, in particular between two juxtaposed blades. A flow rectifying effect is here obtained preferentially in conjunction with the shape of the vanes, which are not planar. We speak of conjugate design of the shape of the blades and the internal wall of the associated channel and / or the static core.

Furthermore, a separating piece is disposed in said at least one peripheral channel, between the inlet and the outlet of said fluid, said separating piece having a shape and means for progressively lowering the pressure of said fluid before recirculation. Since the fluid passes several times between the vanes before being evacuated from the channel in question, this separation piece between the inlet and the outlet of the channel in question is important for the good recirculation of the fluid and especially in order to reduce the losses. charge.

According to one embodiment of the invention, the blades constituting said at least one first series of blades have a so-called circumferential orientation, generally parallel to the axis of said rotor. A third series of blades of the same orientation but arranged symmetrically with respect to the plane of the rotor can be provided without departing from the scope of the invention. Each series of blades is disposed in a specific associated peripheral channel, externally defined by a housing.

Of course each of these embodiments has the dimensional characteristics defined at the head, in particular to increase the yield.

Interestingly, said rotor has a multiplicity of through holes for balancing the induced axial pressures.

According to another characteristic of the invention, the compressor comprises at least one inlet pipe for the fluid, which opens in said at least one peripheral channel and orienting said fluid in a direction opposite or perpendicular to the direction of rotation of said rotor.

When several peripheral channels are provided, they may have cross sections A of different or identical values. The skilled person will choose according to the constraints associated with the case envisaged.

BRIEF DESCRIPTION OF THE FIGURES

• La figure 1 illustre un agencement de compresseur ;
• la figure 2 correspond à un agencement de compresseur auquel l'invention s'applique ;
• la figure 3 est une coupe schématique illustrant certaines relations dimensionnelles caractéristiques de l'invention ;
• la figure 4 est une coupe transversale d'un canal périphérique dans lequel les principaux écoulements sont visibles ;
• les trois schémas de la figure 5 concernent un ratio caractéristique de l'invention ;
• les trois schémas de la figure 6 concernent un autre ratio caractéristique de l'invention ;
• la figure 7 est une vue à plat d'un canal périphérique avec l'écoulement des flux associés ; et
• la figure 8 est une vue à plat d'un canal périphérique avec l'écoulement des flux associés.

Other characteristics, details and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate:

• The figure 1 illustrates a compressor arrangement;
• the figure 2 corresponds to a compressor arrangement to which the invention applies;
• the figure 3 is a schematic section illustrating certain dimensional relationships characteristic of the invention;
• the figure 4 is a cross-section of a peripheral channel in which the main flows are visible;
• the three patterns of the figure 5 relate to a characteristic ratio of the invention;
• the three patterns of the figure 6 relate to another characteristic ratio of the invention;
• the figure 7 is a flat view of a peripheral channel with the flow of the associated flows; and
• the figure 8 is a flat view of a peripheral channel with the flow of associated flows.

For the sake of clarity, identical or similar elements are marked with identical reference signs throughout the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT

The patterns of Figures 1 and 2 relate to compressors provided respectively with a lateral channel and three peripheral channels, two lateral and one radial. Of known structure in itself, these compressors are part of the invention from the moment when characteristic dimensional ratii are provided.

In known manner, therefore, such compressors comprise a wheel or rotor 1 in the form of a circular disk of radius R, to which a series of blades 2 are attached. The series of blades may consist of a set of non-planar blades 2 which have a so-called circumferential orientation, that is to say in a plane more or less close to a circumference of the rotor 1. figure 3 schematically this option. In this same figure has been illustrated the housing 3 of the rotor 1 which substantially conforms to the shape while providing an axial clearance corresponding to leakage zones and pressure drops.

The figure 2 illustrates an embodiment of the invention according to which, typically, the respective arrangements and shapes of the rotors, peripheral channels and blade series are such that the ratio A / R2 is between 6% and 16%; the compressor comprises a third series of blades disposed on an opposite lateral surface of the rotor and in a specific specific channel.

Preferably but not necessarily the rotor 1 has a set of through holes 30 for balancing the various induced axial pressures.

The blades 2 are housed in an annular ring-shaped channel 4 which, moreover, houses a static core 5 which is also annular and coaxial with the rotor 1. The annular channel 4 is advantageously coaxial with the rotor 1 and is termed a 'peripheral' because radial end of the rotor 1.

As already stated, other peripheral channels may be provided, arranged symmetrically vis-à-vis the main plane of the rotor 1 or at the distal and radial end of the rotor 1.

The flow of the fluid in the channel or channels 4 is three-dimensional and complex. The figure 4 shows by a cross section of one of the channels 4, the decomposition of the flow from the inlet 10 of the fluid in the channel 4 to its outlet 20. A flow called circulatory d is generated from the passage between the blade 2. It is a helical flow which causes the fluid to flow several times through the blades 2 before exiting at the outlet 20. A so-called tangential flow c is also created, laminar at the inner wall This flow is created by the blades 2 and its slowing down inside the annular channel 4 creates the pressure in the compressor.

In the intermediate zone between the inlet 10 and the outlet 20 of a channel 4, a so-called recirculation flow is created. A separation part 6 is in particular provided with holes 60 which, associated with its specific shape, make it possible to lower the pressure of the fluid which will recirculate between the outlet 20 and the inlet 10. The arrows f and g of the figure 4 symbolize anterior leakage and so-called posterior leakage respectively.

The invention relates to ratii A / R2 where A is the cross sectional area of at least one of the peripheral channels, and where R is the radius of the rotary wheel 1. The area A corresponds to globally the passage section offered to the fluid to travel the channel, from the inlet 10 to the exit 20. Interestingly and surprisingly it has been found that a ratio A / R2 between 8% and 16% allows optimize the efficiency of the compressor.

The figure 5 illustrates several ratii that fall within the scope of the invention. At rotor size 1 and blade 2 equal, the size of the free channel 4 can vary in the characteristic proportions of the invention. It is the dimensions of the blades 2 which, at equal size, make it possible to be in a configuration according to the invention. The clearance (distance) between the blades 2 and the core 5 may be constant or not.

Furthermore, it has been found that the width h of the blades 2 relative to the radius R of the rotor 1 must remain in such proportions that h / R is between 5% and 15%. By width is meant the dimension of a blade 2 measured either parallel to or perpendicular to the axis XX of rotation of the rotor 1; parallel in the case where the vanes are oriented circumferentially to the axis XX of the rotor as illustrated by the Figures 1, 3 , 5 or 6 ; perpendicular to the axis XX in the case of blades oriented along the main plane of the rotor 1.

This feature is particularly interesting for increasing compressor performance by decreasing the relative share of leaks.

As visible schematically on the figure 4 an inlet pipe 11 opens into the channel 4 with a preferred orientation; this orientation must be different from the perpendicular to the plane of the rotor 1. It will preferentially choose an orientation of the inlet pipe 11 in the retrograde direction of the wheel, that is to say in opposition to the direction of rotation of the wheel 1.

Near the inlet 10 the mean helical flow of the fluid in the channel 4 is disturbed, especially since the inlet port 10 is important. The larger the size of the inlet orifice 10, the smaller the dimension of the channel 4 effective for compression.

It is furthermore preferable to place the inlet opening 10 below the core 5, for example as illustrated by the square 4 on the figure 1 . With regard to the exit opening 20, it is preferentially placed above the core 5, that is to say at a point marked 1 in the square of the figure 1 . The orientation of the outlet pipe 21 associated with the opening 20 will be almost tangential, highly progressive (depending on the direction of rotation of the rotor). It is thus sought to minimize the pressure drop and induce a movement close to that of the mean flow.

The figure 7 is a solid surface showing the progression of the fluid in a peripheral channel, more particularly the flow between the blades 2 and around the static core 5, from the inlet 10 to the outlet 20 of the channel. The graphs at different points of the flux correspond to the total velocity of the fluid combining the circulation around the nucleus (ordinate) as a function of its progression between the inlet 10 and the exit 20 (abscissa) at certain points of the channel 4.

It's about straightening the flow during the passage from dawn to dawn juxtaposed. To do this the shape of the blades 2 is important and it will be chosen non-planar.

It is also preferred, in order to further straighten the flow between two blades 2, to provide reliefs such as grooves or baffles in the inner wall of the channel housing or on the wall of the core 5. figure 8 schematically illustrates the effects of this feature to optimize the flow from the output of a blade to the entry at the next dawn. It's about optimizing velocities and pressures at each point of the flow and decrease turbulence losses between two different pressure zones to reduce their variations when passing between two blades.

Other modifications may be made by those skilled in the art without departing from the scope of the invention. In particular when several peripheral channels are provided, their respective dimensions are not necessarily equal; the areas A of each channel considered may be different; however, each area A in particular responds to the ratio A / R2 characteristic of the invention.

The compressor according to the invention achieves adiabatic efficiencies of about 60%. Many types of gas can be used according to the invention: pure gases, corrosive, explosive or flammable. The pressure variation can reach 40 bars and the compression ratio is greater than 3. These performances are little affected by the operating conditions. By way of illustration, the inlet pressure can reach a value up to 200 bars with a temperature of the order of 200 ° C., a flow rate of 60,000 Nm3 / h. The rotational speeds are low, of the order of 100m / s. The seals used may be carbon seals. Such a compressor is economical because it requires reduced maintenance, small dimensions and low installation costs. The lubrication system is very simple to implement and, contrary to the centrifugal compressors, no anti-pumping system is necessary.

The envisaged applications relate for example to the production of natural gas: the invention can be integrated in a regeneration circulator of a drying sieve. Concerning the cogeneration, the compressors according to the invention can for example be used for the supply of TAG.

Other applications concern biogas blowers, blowers used in various industrial processes, oxygenation for fish farming, freeze-drying etc.

Claims (8)

1. Rotary compressor comprising a disc-shaped rotor (1) having a radius R and supporting on the periphery thereof at least one first series of non-planar blades (2) arranged on a side face of the rotor (1), intended for accelerating the fluid to be compressed between an intake (10) and an outlet (20), a casing (3) defining on the outside at least one generally toroidal channel (4) that is peripheral to the rotor (1), and being coaxial, arranged at the radial end of said rotor (1) and housing said blades (2), a static and annular core (5) being arranged inside of said at least one toroidal channel (4) in such a way as to define with said casing (3) a free cross section A, the compressor comprising a separation part (60) arranged in said at least one peripheral channel, between the intake (10) and the outlet (20) of said fluid, said separation part having a shape making it possible to progressively lower the pressure of said fluid before the intake of the fluid, characterised in that it comprising a second series of blades arranged in the radial extension of said rotor in a given specific channel, and that the dispositions and respective forms of the rotor (1), of at least one peripheral channel (4) and of said at least one first series of blades (2) a second series of blades are such that the ratio A/R² is between 6% and 16%.
2. Rotary compressor according to daim 1 characterised in that said at least one first series of blades (2) has a dimension h measured parallel to or perpendicular to the axis XX of rotation of the rotor, said dimension h being such that the ratio h/R is between 5% and 15%.
3. Rotary compressor according to one of the preceding daim characterised in that said casing (3) of said at least one peripheral channel/or said static core (5) has reliefs intended to modify the direction of the fluid that flows inside said peripheral channel (4) in particular between two juxtaposed blades.
4. Rotary compressor as according to one of the preceding daim characterised in that the blades (2) constituting said at least one first series of blades has a so-called circumferential orientation, globally parallel to the axis of said rotor (1).
5. Rotary compressor according to one of the preceding daim characterised in that it comprises two series of blades arranged symmetrically on either side of the main plane of said rotor, each series being arranged in a specific peripheral channel.
6. Rotary compressor according to one of the preceding daim characterised in that said rotor (1) has a multiplicity of through-holes intended to balance the induced axial pressures.
7. Rotary compressor according to one of the preceding daim, characterised in that it comprises at least one intake stub pipe (11) for the fluid, that exits into said at least one peripheral channel and directs therein said fluid in a direction opposite or perpendicular to the direction of rotation of said rotor.
8. Rotary compressor according to one of the preceding daim, characterised in that it comprises several peripheral channels that have free cross sections A with different values.

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