Patent Application
20240309878
The disclosure concerns improvement in gas compressors. Specifically, embodiments disclosed herein concern integrally geared compressors.
Integrally geared compressors are often use to process air, carbon dioxide or steam. One advantage of integrally geared compressors is the possibility of multiple intercooling between compressor stages, as well as the possibility of driving sequentially arranged compressor stages at different rotational speeds.
GB1048966 discloses a compressor arrangement including an electric motor which drives a main gear meshing with a first pinion at a first end of a first compressor shaft and with a second pinion at a first end of a second compressor shaft. A first compressor is drivingly coupled to the second end of the first compressor shaft and a second compressor is drivingly coupled to the second end of the second compressor shaft.
US2016/0230771 discloses a bull gear compressor including a bull gear driven into rotation by a steam turbine. The steam turbine is drivingly coupled to a driving shaft coupled to the bull gear through a pinion keyed on the driving shaft. A main compressor is directly driven by the driving shaft. Further compressor units are drivingly coupled to the bull gear through driven shafts arranged peripherally around the bull gear.
Integrally geared compressors of the current art still suffer from some limitations. In particular, the inlet volumetric flow rate is limited. In order to improve the inlet flow rate, larger impellers have been developed, but this calls for a reduction of the rotational speed. As an alternative, double flow machines have been envisaged, wherein the first compression stage is split into two separate impellers, which operate in parallel, such that a larger volumetric inlet flow can be processed by the same machine. Double flow integrally geared compressors are cumbersome and, specifically, have a large footprint.
A need therefore exists for improvements in the design of integrally geared compressors, in order to preserve the advantages of these machines, but removing or alleviating their limitations.
According to one aspect, disclosed herein is a novel structure of an integrally geared compressor including a bull gear supported for rotation in a gear casing, and a plurality of pinion shafts, supported for rotation in the gear casing. Each pinion shaft includes a respective pinion, which meshes with the bull gear.
According to the novel arrangement disclosed herein, a first pinion shaft has a first end drivingly coupled to a first axial compressor unit comprising a gas inlet, a gas outlet and an axial compression wheel, which is supported in an overhung fashion at the first end of the first pinion shaft. A second compressor unit is supported in an overhung fashion at a second end of the first pinion shaft. The gas outlet of the first axial compressor unit is fluidly coupled to a gas inlet of the second compressor unit. A second pinion shaft is drivingly coupled to a compressor arrangement comprising a further compressor unit supported in an overhung fashion at a first end of the second pinion shaft. The further compressor unit is a centrifugal compressor unit.
In some embodiments, the compressor can include more than one axial compressor unit, for instance two axial compressor units arranged at opposite ends of the first pinion shaft.
Further embodiments and advantageous features of the integrally geared compressor are outlined below and set out in the enclosed claims.
Reference is now made briefly to the accompanying drawings, in which:
A novel compressor is disclosed, to improve the inlet flowrate of an integrally geared compressor without increasing the overall footprint of the machine. The compressor comprises a bull gear, which drives into rotation two or more pinion shafts peripherally arranged around the bull gear. Each pinion shaft includes a pinion meshing with the bull gear. The pinions may have different diameters and different number of teeth, so that the pinion shafts revolve at different rotational speeds. A compressor driver is drivingly coupled to a central shaft, which rotates the bull gear. The rotary motion is transmitted, with different transmission ratios, from the bull gear to the pinions meshing therewith. Compressor stages are drivingly coupled to the pinion shafts. The most upstream compressor stage is an axial compressor stage drivingly coupled to a first one of said pinion shafts. The second and subsequent compressor stages can be centrifugal compressor stages, arranged in sequence for further compression of the gas flow delivered by the axial compressor stage. Intercoolers can be provided between one or more pairs of sequentially arranged compressor stages, to remove heat from the partly compressed process gas and improve the overall efficiency of the multistage, integrally geared compressor.
The most upstream axial compressor stage is adapted to process larger inlet flowrates than usual centrifugal compressor stages. A compact machine is thus obtained, adapted to process large amounts of inlet gas.
Turning now to the drawings,
A bull gear 5 is supported for rotation in the casing 3. The bull gear 5 is drivingly coupled to an input shaft 7, which can be driven into rotation by a drive unit 9, for instance an electric motor, or any other suitable drive unit. The bull gear 5 is supported by means of bearings 11, 13, for rotation in the casing 3 around a main rotation axis A-A.
The bull gear 5 can rotate at the speed of the drive unit 9, or at a different speed, e.g., if a speed manipulation device, such as a gearbox 8, is arranged along the shaft line between the drive unit 9 and the input shaft 7
The compressor 1 further includes a plurality of pinion shafts. In
A first pinion shaft 15 is supported for rotation around a rotation axis B-B by means of bearings 17, 19. A first pinion 21 is keyed on, or integrally formed with the first pinion shaft 15. The first pinion 21 meshes with the bull gear 5. The first pinion shaft 15 is therefore driven into rotation by drive unit 9 at a rotational speed which is determined by the transmission ratio between the bull gear 5 and the first pinion 21.
A second pinion shaft 23 is supported for rotation around a rotation axis C-C by means of bearings 25, 27. A second pinion 29 is keyed on, or integrally formed with the second pinion shaft 23. The second pinion 29 meshes with the bull gear 5. The second pinion shaft 23 therefore rotates at a rotational speed which is given by the transmission ratio between the bull gear 5 and the second pinion 29. In some embodiments, the rotation speed of the second pinion shaft 23 can be higher than the rotation speed of the first pinion shaft 15.
In general, the integrally geared compressor 1 includes a first, most upstream axial compressor unit driven by the first pinion shaft 15 at a first rotational speed, and a centrifugal compressor arrangement driven by the second pinion shaft at a second rotational speed. The first rotational speed and the second rotational speed are higher than the rotational speed of the bull gear 5.
The centrifugal compressor arrangement may include one or more centrifugal compressor units. As mentioned, in some embodiments, not shown, a third or further pinion shafts may be provided to drive additional centrifugal compressor units belong-ing to the centrifugal compressor arrangement. As will be described in detail below, in the embodiment of
More specifically, in the embodiment of
The first, second, third and fourth compressor units are arranged in sequence, starting from the most upstream compressor unit 31 to the most downstream compres-sor unit 37, such that process gas is firstly compressed in the axial compressor unit 31, which has a higher volumetric flow rate, and subsequently stepwise compressed in sequence in the remaining centrifugal compressor units 33, 35 and 37.
An intercooler can be provided along the connection line connecting each pair of sequentially arranged compressor units 31-37. By way of example, an intercooler 39 is shown in
The first compressor unit 31 includes a gas inlet 43, a gas outlet 45 and an axial compression wheel 47 therebetween. In the embodiment of
In the embodiment of
In the embodiment of
Each compressor unit 33, 35 and 37 includes one or more centrifugal compressor stages. In the embodiment of
In the embodiment of
Similarly, the third compressor unit 35 is a centrifugal compressor unit comprising a centrifugal impeller 61 mounted in an overhung fashion on the first end of the second pinion shaft 23 and rotatingly arranged in a casing 73, having a gas inlet 75 and a gas outlet 77. A vaned or non-vaned diffuser 79 can be arranged between the centrifugal impeller 61 and the gas outlet 77. The gas inlet 75 is fluidly coupled with the gas outlet 67 of the second compressor unit 33 through a connection line, not shown, along which an intercooler can be provided, similarly to intercooler 39 along line 41.
The fourth compressor unit 37 is a centrifugal compressor unit comprising a centrifugal impeller 81 mounted in an overhung fashion on the second end of the second pinion shaft 23 and rotatingly arranged in a casing 83, having a gas inlet 85 and a gas outlet 87. A vaned or non-vaned diffuser 89 can be arranged between the centrifugal impeller 81 and the gas outlet 87. The gas inlet 85 is fluidly coupled with the gas outlet 77 of the third compressor unit 35. An intercooler can be provided along a connection line, not shown, between the third compressor unit 35 and the fourth compressor unit 37.
The compressor 1 is therefore configured to process a gas flow entering the first axial compressor unit 31 first, and subsequently further compressed in the second, third and fourth centrifugal compressor units 33, 35 and 37 in sequence. The axial compression wheel 47 and the centrifugal compressor impeller 61 of the compressor unit 33 rotate at the same rotational speed. The impellers 71 and 81 of the third and fourth compressor units 35 and 37 rotate at the same rotational speed, which is prefer-ably different from the rotational speed of the axial compression wheel 47 and of the centrifugal impeller 61.
In some embodiments, the rotational speed of the second pinion shaft 23, the centrifugal impeller 71 and the centrifugal impeller 81 is higher than the rotational speed of the first pinion shaft 15 and of the axial wheel 47 and centrifugal impeller 61 keyed thereon. The ratio between the rotational speeds of the first and second pinion shafts 15, 23 is given by the ratio between the number of teeth of the pinions 21 and 29. By designing the bull gear 5 and the pinions 21, 29 with the proper number of teeth, the optimum rotational speed ratios for a given application of the compressor 1 can be set.
The axial compressor stage 31 can include a high Mach axial wheel to in-crease the maximum flowrate in the first compression unit, without making recourse to a double flow architecture and to excessively large impeller sizes. A compact compressor with reduced footprint and high efficiency is thus obtained.
The embodiment disclosed so far is by way of example. In other embodiments, not shown, the integrally geared compressor can include more than one axial compressor unit. For instance, a first pinion shaft may be drivingly coupled to an axial compressor unit at both the first end and second end thereof.
Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the scope of the invention as defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021000017996 | Jul 2021 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/025301 | 6/30/2022 | WO |
