WO1987003051A1

WO1987003051A1 - Gaseous fluid compressor associated to a gas-liquid separator

Info

Publication number: WO1987003051A1
Application number: PCT/FR1986/000377
Authority: WO
Inventors: Alain Verneau; René BOURASSIN; Pierre Sagnes
Original assignee: Bertin & Cie
Priority date: 1985-11-08
Filing date: 1986-11-06
Publication date: 1987-05-21
Also published as: FR2589957A1; EP0246261A1; FR2589957B1

Abstract

The compressor associated to a gas-liquid separator is comprised of a centrifugation device mounted in the housing (18) of the compressor and comprising a blade wheel (20) rotatingly driven by the compressor and consisting of an outer tubular envelope (24) guiding the liquid separated from the gas by centrifugation towards a collection chamber (34) comprising means (36, 38) for drawing and discharging the liquid.

Description

Gaseous fluid compressor, associated with a gas-liquid separator.

Technical area

The invention relates to a gaseous fluid compressor which is associated with a gas-liquid separator placed upstream of the compressor to receive a mixture of gas and liquid, separate the liquid from the gas and supply the compressor only with gaseous fluid.

It is known that it is impossible to use centrifugal compressors, axial or peripheral, to compress a mixture of gas and liquid, because of the erosion that the liquid would cause on the leading edge of the blades of the compressor, and unbalance which would be generated by the gas-liquid separation inside the wheels of the presser. PRIOR ART To solve this problem, it has already been proposed to combine a compressor with a gas-liquid separator of the static type which is placed upstream of the compressor and which separates the gas and the liquid in order to supply the compressor only with gas. However, such a static separator has a relatively high cost and a very large footprint compared to that of the compressor, this footprint can reach several tens of m3 when the gas flow to be treated is large. US Pat. No. 3,104,964 discloses a gas-liquid separator which comprises a blade wheel placed at the inlet of the compressor. The liquid droplets entrained by the gas are separated from the gas by impact on the blades of this wheel and are ^' centrifuged radially inside the blade wheel towards the outer fairing of the latter, then led to a groove of weak depth.

The disadvantages of this known device are that it does not make it possible to separate droplets of liquid having a small size from the gas, and that it can only function if the gas contains a small proportion of liquid, due to the very small dimension of the collection groove.

Statement of the invention

The object of the invention is in particular to avoid these various drawbacks.

It proposes a gaseous fluid compressor, associated with a centrifugal gas-liquid separator which ^" is placed at the inlet of the compressor, inside the casing thereof, to supply it essentially with gaseous fluid and which comprises a blade wheel rotated by the compressor shaft, characterized in that it comprises, upstream of said blade wheel, fixed curved fins for rotating the gas-liquid mixture; and in that said wheel blades includes blades or blades at its upstream and downstream ends by which it is integral with an elongated tubular outer shell inside which the gas-liquid separation is effected by centrifugation.

Thanks to the invention, the gas-liquid mixture is rotated inside the tubular envelope, and the liquid is separated by centrifugation of the gas, which allows to separate droplets of liquid having a size very small, of the order of 5 mm for example. In addition, the separator-compressor assembly is in an integrated and compact form and is easy to install, the size of the centrifuge device being no greater than that of the compressor itself.

According to yet another characteristic of the invention, a liquid collection chamber is associated with the centrifugation device and comprises means for withdrawing liquid.

This collection chamber can be located either at the upstream end of the centrifuge device, or at its downstream end, or in between.

The liquid withdrawal means can comprise a fixed impeller, of the centripe turbine wheel type which is supplied with liquid by the collection chamber and which is connected to a liquid passage opening out of the compressor casing.

When the liquid flow rate is relatively low, the liquid withdrawal means may comprise a fixed profiled scoop, of the Pitot tube type, connected to a liquid passage opening out of the compressor casing.

These withdrawal means advantageously make it possible to recover a large part of the liquid kinetic energy and to transform it into pressure energy, so that it is not necessary to use a pump p outlet of the liquid outside the separator-compressor assembly housing.

The liquid sampling means may also comprise, or be constituted by nozzles carried by the peripheral surface of the collection chamber and which open out of this chamber into a fixed diffuser mounted in the casing of the compressor. The separator-compressor assembly according to the invention can comprise a radial gas supply with a gas-liquid mixture and then comprises a supply volute comprising fixed distribution fins and fixed fins for rotating the gas-liquid mixture. .

Alternatively, the whole

can be axially powered, by means of a çσr uit comprising a fixed central core housing bearings and seals cooperating with the compressor shaft and connected to a tubular casing by curved blades for rotating the mixture gas-liquid.

The invention is applicable in particular to a high power compressor, for example a compressor of about 12 megawatts used for the compression, in a ratio 2, of a flow of natural gas of the order of 10'm3 standard per day , may contain up to 50% by mass of liquid.

Brief description of the drawings - In the following description, made in tit _. re example, we refer to the accompanying drawings, in which:

- Figure 1 is a schematic half-view in axial section of a separator-compressor assembly according to the invention; - Figure 2 is a partial view developed flat showing both the arrangements of fins and blades of the separator-compressor assembly according to the invention;

- Figure 3 is a schematic half-view in axial section of another embodiment of a separator-compressor assembly according to the invention;

FIG. 4 is a partial view developed in a flat view representing the arrangement of the fins and blades of a part of the assembly of FIG. 3.

Ways of Carrying Out the Invention Referring first to FIGS. 1 and 2, showing a first embodiment of a separator-compres assembly according to the invention. The compressor shown in FIG. 1 is a two-stage centrifugal compressor, comprising two impellers 10 and 12 integral with a shaft 14 for driving in rotation and mounted in a casing 16 of conventional type.

5

The front part 18 of the casing 16 contains a gas-liquid separator, constituted by a centrifuge device comprising a impeller 20 with blades, which is for example integral in rotation with the wheel 10 of the first stage of the compressor, and which is constituted by an internal cylindrical ring 22 and an external tubular ring 24 connected together, at the upstream end of the device, by planar vanes 26 parallel to the axis of rotation and, at the downstream end of the device, by planar blades 28 who are angu-

15 in line with the upstream ends of the blades 11 of the input wheel 10 of the compressor. The outer ring 24 constitutes the outer casing of the centrifu¬ gation device and comprises for example, at its downstream end, an annular flange 30 by which it can be fixed

2 _Q on a corresponding annular flange 32 of the input wheel 10 of the compressor.

This outer ring 24 is slightly frustoconical in shape and widens in the direction of the input wheel 10 25 of the compressor. Chabrage of the internal surface of the ring 24, at its downstream end, forms a chamber 34 for collecting liquid which contains means for taking liquid.

30 When the flow rate of liquid to be withdrawn is not too great, these means can be constituted, as shown in FIG. 1, by a fixed profiled scoop 36, of the Pitot tube type, the radially outer end of which is located in collection chamber 34 and the end of which

35 opposite mite is connected to a fixed duct 38 disposed between the inner ring 22 of the centrifuge device and the shaft 14 of the compressor, this duct 38 terminating outside the compressor casing. As a variant, the liquid collection chamber 34 and the withdrawal means 36 could be arranged at the upstream end of the centrifugation device, so as not to disturb the flow of gas at the inlet of the compressor.

5

The housing of the separator-compressor assembly can be axially supplied with a gas-liquid mixture, as shown in FIG. 1, and is associated in this case with a fixed supply duct comprising an axial housing 42 and a central core. 44 which surrounds the upstream end of the shaft d. "Drive 14 and makes it possible to house the bearings and garni¬ tures of sealing sealing cooperating with this end of the shaft 14. The casing 42 and the central core 44 are connected by curved fins 46 carrying out a rotation of the gas-liquid mixture corresponding to the direction of rotation of the centrifuge device indicated by the arrow 40 in FIG. 2.

The liquid outlet conduit 38 is extended upstream 2 _Q to the central core 44 and passes radially through the supply conduit to terminate outside of the latter.

The operation of this set is as follows:

The gas-liquid mixture flowing in the casing 42 undergoes a deflection when it meets the central core 44 of the supply duct. This deviation makes it possible to recover, on the internal wall of the casing 42, the largest droplets of liquid which will progress over this

_, _Q internal wall of the casing 42 and which will penetrate into the blade wheel 20 at the periphery thereof, by meeting the upstream ends of the blades. 26 in areas where these blades are reinforced by their connection leave to the outer ring 24.

35

The gas-liquid mixture circulating in the supply line is rotated around the axis of the shaft 14 by the curved fins 46, which transform the flow substantially axial of the gas-liquid mixture in a helical flow, which is taken up by the paddle wheel 20 of the centrifuge device. Inside this wheel, the liquid droplets are separated from the gas by centrifugal effect and progress inside the envelope 24 towards the collection chamber 34, where the liquid is taken up by the scoop 36 and directed outward through the conduit 38. Inside the bladed wheel 20, the relative movement of the gas relative to this 0 bladed wheel is an axial flow towards the inlet wheel 10 of the compressor .

Referring now to Figures 3 and 4 showing another embodiment of the separator assembly - - _j c compressor according to the invention.

In general, this other embodiment differs from that of FIGS. 1 and 2 in that the assembly comprises a radial conduit for supplying a gas-liquid mixture, in that the collection chamber and the sampling means liquid are located at the upstream end of the separator and in that the compressor comprises three centrifugal stages,

More specifically, the separator-compressor assembly 25 comprises a casing 50, the ends of which are respectively connected to a radial duct 52 for supplying gas-liquid mixture and to a radial duct 54 for the outlet of compressed gas. The radial supply duct 52 opens into a volute 56 comprising, at its upstream end, 30 fixed fins 58 for distribution and, at its downstream end, fins. fixed 60 for rotating the gas-liquid mixture.

The volute 56 opens into a chamber 62 for collecting liquid 35, situated between the downstream end of the volute 56 and the upstream end of the gas-liquid separator. This collection chamber 62 contains means for withdrawing liquid, which in this example consist of a fixed wheel 64 with blades, of the centripetal turbine wheel type, the inlet of which is in the immediate vicinity of the peripheral wall of the collection chamber 62, and the outlet of which is connected to a volute 66 housed inside the casing 50 and terminating on the outside thereof.

As in the previous embodiment, the separator is formed by a centrifugation device comprising a wheel 68 with blades, constituted by an internal cylindrical ring 70 integral in rotation with the shaft 72 of the compressor, an external tubular casing 74 of truncated shape, and vanes or blades 76,78 connecting the inner ring 70 to the outer tubular casing 74 at their upstream and downstream ends respectively.

The external tubular envelope 74 widens in the direction of the collection chamber 62.

The vanes 76 at the inlet of the centrifuge device are curved so as to participate in the rotation around the axis of the shaft 72 of the gas-liquid mixture, while the blades 78 at the outlet of the device are straight and parallel to the axis of rotation, being angularly aligned with the upstream ends of the vanes 80 of the input wheel 82 of the compressor.

As indicated above, this compressor has three stages and therefore comprises two other impellers 84 and 86 respectively, the three wheels rotating inside stators carried by the casing 50.

As seen in FIG. 3, the outlet volutes of the first two stages of the compressor can be formed with calibrated orifices 88 passing through their peripheral wall and forming outlet nozzles for the liquid which would not have been completely separated from the gas. by the centrifugation device. Sets of bearings and seals cooperating with the drive shaft 72 are supported by the supply volute 56 on the one hand and by the right end of the housing 50, on the other hand.

The assembly of FIGS. 3 and 4 works in the following way:

The gas-liquid mixture supplied by the radial duct 52 Q enters the supply volute 56, passes over the distributing fins 58 and over the fins 60 which cause the mixture to rotate. This rotation is accentuated by the inlet vanes 76 of the centrifuge device, which is rotated by the shaft

- e _j 72 in the direction indicated by the arrow 90 in Figure 4. Inside the centrifuge device, the liquid separates from the gas by centrifugal effect, is collected in the collection chamber 62 at the end amont_du device centrifugation, is removed by the fixed rode 64 and

_2Q sent into the outlet volute 66. The wheel 64, of the centripetal turbine wheel type, makes it possible to recover approximately 40% of the kinetic energy of the liquid withdrawn and to transform this energy into pressure energy to drive the liquid to outside the compressor housing without the need to use a pump.

The gas flows almost axially inside the centrifuge device (in relative motion relative to this device) and arrives on the input wheel

30 of the centrifugal compressor. In this compressor, the gas undergoes three successive compressions, then leaves via the radial duct 54.

The very fine droplets of liquid, which can still be transported by the gas, are discharged through the calibrated orifices 88 of the outlet volute of the first stage of the compressor and, possibly, through those of the outlet volute of the second stage. The outgoing liquid through the calibrated orifices 88 is recovered in a fixed diffuser and, if necessary, returned to the supply volute 56.

When the gas-liquid mixture supplying the separator-compressor assembly according to the invention is loaded with solid particles, provision may be made to form the means for taking liquid with a wheel of the centripetal turbine wheel type, as shown in Figure 3, and by ejection nozzles, formed by calibrated orifices of the peripheral wall of the collection chamber at the entrance thereof which let out in a fixed diffuser a small fraction of the liquid collected to evacuate this way the solid particles. Industrial applications possibilities

To fix the ideas, it is specified that a separator-compressor assembly according to the invention can operate under the following conditions:

~ gas-liquid mixture supply pressure: 40 to 150 bars,

- gas-liquid mixture flow rate: approximately 12,000 m3 / hour under supply conditions.

- proportion of liquid in the mixture: from 0 to 50% by mass,

- compressor compression ratio: around 2,

- diameter of the compressor wheels: from 170 to 500 mm approximately, depending on the case.

- rotation speed: from 40,000 to 10,000 revolutions / minute, depending on the diameter of the wheels,

- outside diameter of the bladed wheel of the centrifuge device: approximately 70% of the diameter of the compressor wheels, - length of the paddle wheel: from 300 to 600 mm approximately (for a flow rate of approximately 12,000 m3 / hour), all the liquid droplets having a diameter greater than 7 microns being separated from the gas over a length of 300 mm approximately ^' in the centrifuge.

In general, the dimensions of the collection chamber and of the sampling means are determined for a maximum proportion of liquid capable of being contained in the gas-liquid mixture.

The invention can be used not only for compressing a very high flow rate of natural gas, but also in refineries, in steam treatment plants, as well as in supply systems for special fuels such as those used. in aeronautics and which have saturated vapor pressures such that a mass boiling can occur from a certain altitude.

Claims

Claims.

1. Gaseous fluid compressor, associated with a centrifugal gas-liquid separator which is placed at the inlet of the compressor, inside the casing thereof, for the essential supply of gaseous fluid and which comprises a blade wheel (20,68) rotated by the compressor shaft, characterized in that it comprises, upstream of said blade wheel, fixed curved fins (46.60 for rotating the gas mixture- liquid, and in that said paddle wheel comprises vanes or blades (26,28; 76 78) at its upstream and downstream ends by which it is integral with an allon¬ gated tubular outer casing (24,74) at l within which the separation gas-liquid ^• is effected by centrifugation.

2. Compressor according to claim 1, characterized in that the paddle wheel (20) comprises, at its upstream and downstream ends, blades - (26,28) parallel! ^I the axis of rotation of the wheel. ^" :

3. Compressor according to claim 1 characterized in that the paddle wheel (68) comprises, at its amon end curved blades (76) for rotating the gas-liquid mixture and, at its downstream end, blades (78 ) parallel to the rotatxon axis of the wheel.

4. Compressor according to claim 2 or 3, characterized in that the blades (28,78) at the downstream end of the blade wheel end in the vicinity of the blades (11,80) of the input wheel (10 , 82) of the compressor and are angularly aligned with them.

5. Compressor according to one of the preceding claims, characterized by a chamber (34,62) for collecting liquid formed at an axial end of the centrifugal separator and containing means (36,64) for withdrawing liquid.

_* • • _/ • • •

6. Compressor according to claim 5, characterized in that said collection chamber (62) is upstream of the centrifugal separator.

7. Compressor according to claim 5, characterized in that the collection chamber (34) is downstream of the centrifugal separator.

8. Compressor according to one of claims 5 to 7, charac¬ terized in that the liquid withdrawal means com¬ take a fixed impeller (64), of the centripetal turbine wheel type, supplied with liquid by the chamber collection (62) and connected to a liquid passage (66) opening to the outside of the compressor housing.

9. Compressor according to one of claims 5 to 7, character ized in that the liquid withdrawal means comprise nozzles carried by the peripheral wall of the collection cham and opening out of this chamber da a diffuser fixed mounted in the compressor housing.

10. Compressor according to one of claims 5 to 7, charac terized in that the liquid withdrawal means com¬ take a fixed profiled scoop (36), of the Pito tube type connected to a liquid passage (38) opening outside the compressor housing.

11. Compressor according to one of the preceding claims, characterized in that the tubular casing (24,74) of the centrifugal separator is of frustoconical shape and widens in the direction of the collection chamber (34,62

12. Compressor according to one of the preceding claims, characterized in that the centrifugal separator is ^ axial feed in gas-liquid mixture because a duct comprises a fixed central core (44) housing bearings and σar- Sealing nitrides cooperating with one end of the compressor drive shaft (14) and connected to a tubular casing (42) by the curved fins (46) for rotating the gas-liquid mixture.

13. Compressor according to one of claims l to 11, charac terized in that it comprises a radial duct (52) for supplying gas-liquid mixture, opening into a supply volute (56) comprising distribution fins (58) and the fins (60) for rotating the gas-liquid mixture