Embodiments of the subject matter disclosed herein correspond to gas turbine systems with a bleed routing arrangements.

BACKGROUND ART

In the field of turbomachinery in particular for "Oil & Gas" applications, a gas turbine system comprises a compressor, a combustor and a turbine section; the outlet of the turbine section is fluidly connected to an exhaust duct, usually in the form of a large and tall chimney.

In the field of turbomachinery in particular for "Oil & Gas" applications, a gas turbine system may have other needs to discharge gas or gasses (for example air or vapor) in the environment. In this case, one or more dedicated exhaust ducts are provided. In this way, each exhaust duct is arranged (e.g. shaped and located) so to discharge at best the corresponding gas or gasses. Anyway, this approach may lead to cumbersome arrangements. This is even more true if the massflow of the gas or gasses to be discharged is large.

SUMMARY

Embodiments of the subject matter disclosed herein relate to a gas turbine system.

According to such embodiments, the gas turbine system comprises a compressor section, a combustor section, a turbine section, and a bleed routing arrangement; wherein a main outlet of the turbine section and a main outlet of the bleed routing arrangement are fluidly connected to an exhaust duct, in particular a single exhaust duct. The bleed routing arrangement may be for example a duct or a plurality of pipes. Advantageously, the gas turbine system comprises further a connection joint (60) with a stilling volume or chamber at the outlet of the bleed routing arrangement. The bleed routing arrangement has typically an inlet fluidly connected to a bleed outlet of the compressor section, and an outlet fluidly connected to the exhaust duct of the gas turbine system, for example the lower side of a chimney.

The bleed outlet of the compressor section is typically between a low-pressure compressor portion and a high-pressure compressor portion.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated herein and constitute an integral part of the present specification, illustrate exemplary embodiments of the present invention and, together with the detailed description, explain these embodiments. In the drawings:

Fig. 1 shows an architecture applicable to embodiments of a gas turbine system;

Fig. 2 shows a schematic lateral view of a first embodiment of a gas turbine system;

Fig. 3 shows a schematic top view of a connection duct of the system of Fig. 2;

Fig. 4 shows a schematic lateral view of a connection joint of the system of Fig. 2; Fig. 5 shows a schematic lateral view of connection pipes that may be used in the system of Fig. 2;

Fig. 6 shows a schematic cross-section view of Fig. 5; and

Fig. 7 shows a schematic lateral view of a second embodiment of a gas turbine system. DETAILED DESCRIPTION

The following description of exemplary embodiments refers to the accompanying drawings.

The following description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

According to the architecture of Fig. 1, a gas turbine system 101 comprises: a compressor section 1 ; a combustor section 2; a turbine section 3; and a bleed routing arrangement 5 fluidly connected to the compressor section 1 ; a main outlet 37 (this reference number will be explained later when describing a first embodiment and a second embodiment) of the turbine section 3 and a main outlet 59 (this reference number will be explained later when describing a first embodiment and a second embodiment) of the bleed routing arrangement 5 are fluidly connected to an exhaust duct 4.

Such architecture is very general: the compressor section 1 may have one or more shafts (mechanically connected or disconnected) and/or may be divided in one or more compressor portions (for example machines) (so it may be a "multi-spool axial compressor"), the turbine section 3 may have one or more shafts (mechanically connected or disconnected) and/or may be divided in one or more turbine portions (for example machines), the exhaust duct 4 may be fluidly connected directly or indirectly to the main outlet of the turbine section and directly or indirectly to the main outlet of the bleed routing arrangement, the bleed routing arrangement 5 may be fluidly connected directly or indirectly to any point and in any way to the compressor section. Fig. 2 shows a first embodiment of a gas turbine system 201 comprising a compressor section 10, a combustor section 20 and a turbine section 30.

It is to be noted that the embodiments of Fig. 2 and of Fig. 7 are very similar; the same or corresponding elements are labelled with the same reference numbers. The compressor section 10 has a main inlet 11, a main outlet 17, and a bleed outlet 18.

The combustor section 20 has a main inlet 21 and a main outlet 29.

The turbine section 30 has a main inlet 31 and a main outlet 37.

The main inlet 21 of the combustor section 20 is fluidly connected to the main outlet 17 of the compressor section 10; the main outlet 29 of the combustor section 20 is fluidly connected to the main inlet 31 of the turbine section 30.

The main outlet 37 of the turbine section 30 is fluidly connected to an exhaust duct 40 of the gas turbine system 101; the exhaust duct may be the form of a large and tall chimney; in the embodiment of Fig. 2, between the outlet 37 and the duct 40 there is a plenum chamber 38 and a connection joint 60. The gas turbine system 101 comprises a bleed routing arrangement 50 (in particular a connection duct as shown in Fig. 3) with an inlet 51 and an outlet 59. The inlet 51 is fluidly connected to the bleed outlet 18 of the compressor section 10, and an outlet 59 is fluidly connected to the exhaust duct 40 of the gas turbine system 101; in the embodiment of Fig. 2, between the outlet 59 and the duct 40 there is a connection joint 60.

In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the bleed routing arrangement 50 is arranged to avoid surge at partial load operation; to be precise, such bleed routing arrangement can avoid surge when it is used in a gas turbine system and its bleed flow is appropriately started and stopped. In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the turbine section 30 comprises at least a high-pressure turbine portion 32 (in particular a first turbine machine) and a low-pressure turbine portion 36 (in particular a second turbine machine) fluidly connected downstream the high-pressure turbine portion 31; other turbine portions may be present, for example a medium-pressure turbine portion. In particular, the turbine portions 32 and 36 have separate and disconnected shafts (these shafts are not shown in any of the figures but a separation 34 is highlighted between the two adjacent portions).

In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the compressor section 10 comprises at least a low-pressure compressor portion 12 (in particular a first compressor machine) and a high-pressure compressor portion 16 (in particular a second compressor machine) fluidly connected downstream the low-pressure compressor portion 12; other compressor portions may be present, for example a medium-pressure compressor portion. In particular, the compressor portions 12 and 16 have separate and disconnected shafts (these shafts are not shown in any of the figures but a separation 14 is highlighted between the two adjacent portions).

In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the shaft of the low-pressure compressor portion 12 is mechanically connected to (i.e. driven by) the shaft of the low-pressure turbine portion 36.

In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the shaft of the high-pressure compressor portion 16 is mechanically connected to (i.e. driven by) the shaft of the high-pressure turbine portion 32. In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the bleed outlet 18 is between the low-pressure compressor portion 12 and the high-pressure compressor portion 16; this means that the pressure at the inlet of the bleed routing arrangement 50 is quite low (the value depends on the specific application); the massflow that is necessary for avoiding surge is typically quite high (the value depends on the specific application) so the cross-section area of the bleed routing arrangement is typically quite large. The compressor section 10 comprises one or more valves 19 at the bleed outlet 18 (that may correspond to one or more holes in the compressor case or in a peripheral wall of a collector) so that the bleed flow may be established at certain first operating conditions of the gas turbine system 101 and may be stopped at certain second operating conditions. In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the bleed outlet 18 of the compressor section 10 is fluidly connected to a collector duct 14 that is typically annular-shaped.

In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the main outlet 37 of the turbine section 30 is fluidly connected to a plenum chamber 38. In particular, the connection joint 60 is radially displaced from the main outlet 37. In particular, the connection joint 60 is on one side of the plenum chamber 38.

In the embodiment of Fig. 2, the bleed routing arrangement consists of a connection duct 50 (see also Fig. 3) for example with a (substantially) rectangular cross-section. The connection duct 50 may have an isolated through hole 55 used as passage for a ventilation flow (in particular for ventilating and cooling the gas turbine system), as it is shown well in Fig. 3; the ventilation flow is maintained separate from the flow inside the duct 50. The hole 55 is transversal to the duct 50. The hole 55 is closer to the outlet 59 than to the inlet 51; in particular, the hole 55 is closer to the outlet 59 than to the inlet 51 since such positioning helps dissipating the heat generated on top of the combustor and turbine casing.

The connection duct 50 may have one or more internal flow partition elements additionally or alternatively to the through hole. In Fig. 3, for example, the two elements 57 extend along a substantial part of the duct 50 while the two element 56 extend along a small part of the duct 50; many other combinations of positions and lengths may be used depending on the circumstances.

The through hole and/or the flow partition elements may contribute to limit or avoid "back-flow" of exhaust gasses in particular by means of damping flow recirculation phenomena inside the duct. The flow partition elements may contribute to reduce noise, i.e. they may act as "silencer panels" for damping the bleed flow acoustic emissions.

As shown in Fig. 5 and Fig. 6, the bleed routing arrangement may consist as a plurality of connection pipes 50-1, 50-2, 50-3, 50-4 for example with a (substantially) circular cross-section; in these figures, there are four pipes; in these figures, the pipes are parallel to the axis of the system; their inlets (51-1 and 51-3 in Fig. 5) are fluidly connected for example to the annular collector 14.

In the embodiment of Fig. 7, there is an annular duct 70 around exhaust duct 40 for the ventilation flow (in particular for ventilating and cooling the gas turbine system); the annular duct 70 is preferably coaxial to the exhaust duct 40. Additionally, in the embodiment of Fig. 7, the gas exits the duct 70 in a substantially horizontal direction and the gas exits the duct 40 is a substantially vertical direction.

The configuration of Fig. 7 allows achieving a further simplification; in fact, the gas turbine system has a single exhaust duct assembly comprising: a turbine exhaust duct, an anti-surge bleed exhaust duct and a ventilation exhaust duct. This solution allows to significantly reduce the overall dimension of the gas turbine system. Moreover, the ventilation flow, used for ventilating and cooling the gas turbine, by flowing over the external surface of the exhaust duct 40 allows to cool it. As shown in Fig. 7, the exhaust duct assembly is advantageously arranged so to keep turbine exhaust gases separate from ventilation exhaust gases (typically air). This is the only difference between the embodiment of Fig. 2 and the embodiment of Fig. 7.

Preferably, there is an expansion joint (not shown in the figures) between the inlet 51 of the connection duct 50 and the bleed outlet 18 of the compressor section 10. In the embodiment of Fig. 2 (as well as in the embodiment of Fig. 7), the gas turbine system 201 comprises a connection joint 60 fluidly connecting the main outlet 37 of the turbine section 30 (indirectly) and the outlet 59 of the bleed routing arrangement 50 directly to the exhaust duct 40 of the gas turbine system.

Preferably, there is an expansion joint (not shown in the figures) between the main outlet 37 of the turbine section 30 and the connection joint 60; in particular, it is downstream the plenum chamber 38. The connection joint 60 is preferably arranged to limit or avoid flow of exhaust gas (so- called "back-flow") from the main outlet 37 of the turbine section 30 into the bleed routing arrangement 50 through its outlet 59 which is likely to occur especially when there is no bleed flow (i.e. "bleed" is off) or little bleed flow. Such "back-flow" is at least partially due to the fact that the exhaust flow is highly turbulent and non-uniform.

In the embodiment of Fig. 2, exhaust duct 40 gradually diverge laterally starting from connection joint 60 (till a certain distance from connection joint 60) so that its cross- section gradually increases; there may be a divergence of exhaust duct 40 on one or two or three or four sides of exhaust duct 40. The connection joint 60 comprises a frame 61 that may be, for example, square or rectangular.

According to the embodiment of Fig. 4, the connection joint 60 comprises a stilling volume or chamber 63 at the outlet 59 of the connection duct 50; this helps in limiting or avoiding the above mentioned "back-flow". The stilling chamber is a volume at the outlet of the connection duct that prolongs inside the exhaust duct and has a sufficient length so to help in keeping the bleed flow separate from the exhaust flow and let them merge where turbulence (especially in the exhaust flow) is relatively low. Furthermore, such separation is useful also when there is no bleed flow (i.e. "bleed" is off) or little bleed flow; in fact, as turbulence in the exhaust flow at the end of the stilling chamber (at the top in Fig. 2 and Fig. 4) is relatively low, no exhaust or little exhaust gas tends to reflow into the routing arrangement 50 through the stilling chamber.

In order to further limit or avoid completely the above mentioned "back-flow", the connection joint 60 may also comprise a perforated plate 65 at the outlet 59 of the bleed routing arrangement 50, in particular at the outlet of the stilling volume or chamber 63; the perforated plate is sized so to avoid excessive pressure drop across the bleed routing arrangement, i.e. from inlet 51 to outlet 59, while preventing exhaust gasses from flowing back from outlet 59 to inlet 51. In order to avoid the above mentioned "back- flow" when the bleed flow is not present, the connection joint 60 may comprise one or more valves (possibility not shown in any of the figures) at the outlet 59 of the bleed routing arrangement 50.