Patent Description:
A turbomachine refers to an apparatus that generates power for power generation through a fluid (particularly, for example, gas) passing through the turbomachine. Therefore, the turbomachine is usually installed and used together with a generator. Such a turbomachine may include a gas turbine, a steam turbine, a wind power turbine, and the like. The gas turbine is an apparatus that mixes compressed air and natural gas and combusts an air-fuel mixture to generate combustion gas, which in turn generates power for power generation. The steam turbine is an apparatus that heats water to generate steam, which in turn generates power for power generation. The wind turbine is an apparatus that converts wind power into power for power generation.

Among the turbomachines, the gas turbine includes a compressor, a combustor, and a turbine. The compressor has a plurality of compressor vanes and compressor blades alternately arranged within a compressor casing. In addition, the compressor sucks external air through a compressor inlet scroll strut. The sucked air is compressed by the compressor vanes and the compressor blades while passing through an interior of the compressor. The combustor receives the compressed air from the compressor and mixes the compressed air with fuel to form a fuel-air mixture. In addition, the combustor ignites the fuel-air mixture with an igniter to generate high-temperature and high-pressure combustion gas. The generated combustion gas is supplied to the turbine. In the turbine, a plurality of turbine vanes and turbine blades are arranged in a turbine casing. The combustion gas generated by the combustor passes through the turbine. While passing through an interior of the turbine, the combustion gas rotates the turbine blades and then is discharged to the outside through a turbine diffuser.

Among the turbomachines, the steam turbine includes an evaporator and a turbine. The evaporator heats water supplied from the outside to generate steam. In the turbine, a plurality of turbine vanes and turbine blades are alternately disposed in a turbine casing, similarly to the turbine in a gas turbine. However, in the turbine in the steam turbine, the steam generated in the evaporator, instead of the combustion gas, passes through the turbine to rotate the turbine blades.

As for the gas turbine, the combustor of the gas turbine is provided with a nozzle for mixing the fuel supplied from the outside and compressed air supplied from the compressor and injecting the air-fuel mixture into the combustor. In addition, a combustion chamber in which the air-fuel mixture is combusted in the combustor is disposed downstream of the nozzle, that is, on the downstream side on the basis of a flow direction of the air-fuel mixture.

At this time, according to the conventional gas turbine, when a material having a high flaming rate, such as hydrogen, is used as fuel, the flame generated in the combustion chamber may flow back forwards, that is, toward the upstream side on the basis of the flow direction of the air-fuel mixture. As the backflow occurs, there is a problem that flashback may occur in the nozzle, which damages the nozzle.

<CIT>discloses a nozzle for a gas turbine according to the prior art.

It is one of the objects of the present invention to provide a combustor having an improved nozzle structure, which is able to prevent the flashback, in which a flame generated in a combustion chamber flows backward, from occurring in a nozzle.

To this end, the present invention provides a combustor in accordance with claim <NUM> and a gas turbine in accordance with claim <NUM>.

According to an aspect of the present invention, there is provided a combustor mixing compressed air supplied from a compressor with fuel and combusting the compressed air-fuel mixture, the combustor including: an outer can into which the fuel is introduced from the outside; an outer head disposed on a front side of the outer can; an inner can disposed inside of the outer can so that the compressed air flows between the inner can and the outer can and having a combustion chamber in which a mixture of the fuel and the compressed air is combusted; and an inner head disposed in front of the inner can to mix the fuel and the compressed air and supply the mixture into the inner can, the inner head including: a head plate covering a front side of the inner can, and a plurality of nozzle assemblies disposed in front of the head plate to mix the fuel and the compressed air and supply the mixture rearwards, the nozzle assemblies each including: a nozzle head into which the fuel is introduced and a plurality of nozzles each arranged such that a front side thereof is coupled to the nozzle head and a rear side thereof is coupled to the head plate so as to mix the fuel and the compressed air and supply the mixture rearwards, wherein the nozzles has a shape with a diameter decreasing and increasing toward the rear side thereof.

According to another aspect of the present invention, there is provided a gas turbine including: a compressor provided to compress external air; a combustor provided to mix the compressed air supplied from the compressor with fuel and combust the compressed air-fuel mixture; and a turbine through which combustion gas supplied from the combustor flows to generate power for generating electricity, the combustor including: an outer can into which the fuel is introduced from the outside; an outer head disposed on a front side of the outer can; an inner can disposed inside of the outer can so that the compressed air flows between the inner can and the outer can and having a combustion chamber in which a mixture of the fuel and the compressed air is combusted; and an inner head disposed in front of the inner can to mix the fuel and the compressed air and supply the mixture into the inner can, the inner head including: a head plate covering a front side of the inner can, and a plurality of nozzle assemblies disposed in front of the head plate to mix the fuel and the compressed air and supply the mixture rearwards, the nozzle assemblies each including: a nozzle head into which the fuel is introduced and a plurality of nozzles each arranged such that a front side thereof is coupled to the nozzle head and a rear side thereof is coupled to the head plate so as to mix the fuel and the compressed air and supply the mixture rearwards, wherein the each nozzle has a shape with a diameter decreasing and increasing toward the rear side thereof.

The plurality of nozzle assemblies may be arranged such that one nozzle assembly from among the plurality of nozzle assemblies is disposed at the center portion of the head plate and the remaining nozzle assemblies from among the plurality of nozzle assemblies are disposed radially around the centrally disposed nozzle assembly, wherein the plurality of nozzles may be arranged such that one nozzles is disposed at the center portion of the nozzle head and the remaining nozzles are disposed radially around the centrally disposed nozzle.

According to the invention, the nozzle head is formed in a hollow plate shape so that the fuel is introduced from a front side thereof, and the nozzles each may include a nozzle decreasing part disposed inside of the nozzle head and having a diameter decreasing toward a rear side thereof, with fuel holes formed through which the fuel introduced into the each nozzle is supplied into the nozzle decreasing part.

The each nozzle may further include a nozzle increasing part disposed on a rear side of the nozzle decreasing part so that fuel and compressed air are supplied from a front side thereof, and coupled to the head plate between the nozzle head and the head plate, the nozzle increasing part having a diameter increasing toward a rear side thereof.

The each nozzle may further include a nozzle inlet part connected to the front side of the nozzle decreasing part, protruding toward the front side of the nozzle head, and having a constant diameter in the front-rear direction, so as to transfer the compressed air introduced from the front side thereof to the nozzle decreasing part.

The each nozzle may further include a nozzle connection part connected between the nozzle decreasing part and the nozzle increasing part to supply fuel and compressed air from the nozzle decreasing part to the nozzle increasing part, the nozzle connection part having a constant diameter in the front-rear direction.

The nozzle increasing part may be provided with a plurality of air through-holes through which compressed air is radially introduced from the outside to the inside thereof, wherein the air through-holes are spaced apart from each other in the front-rear direction, the air through-holes each being formed in a radially inclined shape along the circumferential direction from the outside to the inside of the nozzle increasing part so that the compressed air supplied into the nozzle increasing part swirls.

The fuel holes may each be formed to be inclined rearwards on the basis of the direction of compressed air flowing in the nozzle decreasing part as it goes from the outside to the inside of the nozzle decreasing part in the radial direction.

According to the present invention, the nozzles each installed in front of the inner can is formed in a shape in which the diameter decreases and then increases from the front to the rear, and the fuel is supplied to the portion of the each nozzle where the diameter decreases, so that it is possible to prevent the flashback, in which a flame generated in the combustion chamber flows backward, from occurring in the each nozzle by using a phenomenon that a flow rate of a fluid increases in the nozzle portion where the diameter decreases.

Further, according to an embodiment of the present invention, the secondary compressed air is supplied to the nozzle portion where the diameter increases so that a fuel/air ratio of the fluid flowing adjacent to the inner circumferential surface of the nozzles is reduced, thereby preventing the flame generated in the combustion chamber from flowing backwards along the inner circumferential surface of the nozzles. Specifically, the secondary compressed air induces a swirl effect inside the nozzles to increase the fuel-air mixing efficiency such that the fuel/air ratio at the outlet of the nozzles appears in an M-shape due to the centrally-located primary compressed air and the radially-located fuel in the nozzles and the secondary compressed air outside the nozzles, which enables the low fuel/air ratio at the center of the nozzles to prevent the problem that the flame at the central part of the nozzles is introduced into the nozzles due to the inner recirculation occurring due to the swirl effect.

Although the present invention will be described with reference to embodiments illustrated in the accompanying drawings, those skilled in the art will understand that these embodiments are merely illustrative, and various modifications and equivalent other embodiments may be possible. Therefore, the scope of the present invention is defined by the appended claims.

Referring to <FIG>, a gas turbine <NUM> includes a compressor <NUM>, a combustor <NUM>, and a turbine section <NUM>. In a flow direction of gas (compressed air or combustion gas), the compressor <NUM> is disposed on the upstream side of the gas turbine <NUM>, and the turbine section <NUM> is disposed on the downstream side of the gas turbine. In addition, the combustor <NUM> is arranged between the compressor <NUM> and the turbine section <NUM>.

The compressor <NUM> accommodates, inside a compressor casing, compressor vanes and a compressor rotor including a compressor disk and compressor blades, and the turbine section <NUM> accommodates, inside a turbine casing, turbine vanes and a turbine rotor including a turbine disk and turbine blades. These compressor vanes and the compressor rotor are arranged in a multi-stage along a flow direction of compressed air, and the turbine vanes and the turbine rotor are also arranged in a multi-stage along a flow direction of combustion gas. At this time, it is designed such that the compressor <NUM> has an internal space of which the volume decreases from the front-stage toward the rear-stage so that the intake air can be compressed, whereas the turbine <NUM> has an internal space of which the volume increases from the front-stage toward the rear-stage so that the combustion gas supplied from the combustor <NUM> can expand.

Between the compressor rotor located on the rear end side of the compressor <NUM> and the turbine rotor located on the front end side of the turbine section <NUM>, a torque tube is disposed as a torque transmission member to transmit the rotational torque generated by the turbine section <NUM> to the compressor <NUM>. Although the torque tube may be composed of a plurality of torque tube disks arranged in three stages in total as illustrated in <FIG>, this is only one of several embodiments of the present invention, so the torque tube may be composed of a plurality of torque tube disks arranged in four or more stages or two or less stages.

The compressor rotor includes a compressor disk and a compressor blade. A plurality of (e.g., <NUM>) compressor disks are provided inside the compressor casing, and the respective compressor disks are fastened so as not to be spaced apart in the axial direction by a tie rod. More specifically, the respective compressor disks are aligned along the axial direction with the tie rod passing through the central portion thereof. In addition, adjacent compressor disks are arranged such that the opposing surfaces of the adjacent compressor disks are compressed by the tie rod so that the adjacent compressor disks cannot rotate relative to each other.

The plurality of compressor blades is radially coupled to an outer circumferential surface of the compressor disk in a multi-stage. Further, the plurality of compressor vanes is arranged in a multi-stage on an inner circumferential surface of the compressor casing such that each stage of compressor vanes is disposed between adjacent stages of compressor blades. Unlike the compressor disk, the compressor vanes maintain a fixed state so as not to rotate, and serve to guide the compressed air, which passed through an upstream-side stage of compressor blades, to a downstream-side stage of compressor blades. Here, the compressor casing and the compressor vanes may be collectively defined as a compressor stator to distinguish them from the compressor rotor.

The compressor stator further includes a compressor inlet scroll strut in addition to the compressor casing and the compressor vanes. The compressor inlet scroll strut is connected to a front side of the compressor casing to guide external air to an inlet of the compressor casing. Meanwhile, among the compressor vanes, the foremost compressor vane is referred to as an inlet guide vane. The inlet guide vane serves to guide the air flowing into the compressor casing to the compressor blades and the compressor vanes disposed on the rear side of the compressor casing.

The tie rod is arranged to penetrate the center of the plurality of compressor disks and turbine disks, which will be described later, such that one end thereof is fastened in the compressor disk located on the foremost side of the compressor <NUM> and the other end thereof is fastened by a fastening nut.

Since the tie rod may be formed in various structures depending on the gas turbine, the shape of the tie rod is not necessarily limited to the shape illustrated in <FIG>. That is, as illustrated, one tie rod may have a form in which the tie rod passes through the central portion of the compressor disks and the turbine disks, or a form in which the plurality of tie rods are arranged in a circumferential manner, or a combination thereof.

Although not illustrated, the compressor of the gas turbine may be provided with a deswirler that serves as a guide for increasing a pressure of fluid and adjusting a flow angle of the fluid entering a combustor inlet to a designed flow angle.

The high-temperature and high-pressure combustion gas from the combustor <NUM> is supplied to the turbine section <NUM> described above. The high-temperature and high-pressure combustion gas supplied to the turbine section <NUM> expands while passing through the inside of the turbine section <NUM>, and accordingly, impulses and reaction forces are applied to the turbine blades, which will be described later, to generate rotational torque. The resultant rotational torque is transmitted to the compressor through the above-described torque tube, and an excess of the p ower required to drive the compressor is used to drive a generator or the like.

The turbine section <NUM> is fundamentally similar to the structure of a compressor <NUM>. That is, the turbine section <NUM> is also provided with a plurality of turbine rotors similar to the compressor rotor of the compressor <NUM>. Thus, the turbine rotor includes a turbine disk and a plurality of turbine blades radially disposed around the turbine disk. The plurality of turbine vanes is also annually arranged, on the basis of the same stage, on the turbine casing between adjacent stages of turbine blades to guide a flow direction of the combustion gas, which passed through the turbine blades. Here, the turbine casing and the turbine vanes may be collectively defined as a turbine stator to distinguish them from the turbine rotor.

Referring to <FIG>, the combustor <NUM> according to the present invention includes an outer can <NUM>, an outer head <NUM>, an inner can <NUM>, and an inner head <NUM>. The outer can <NUM> is formed in a hollow cylindrical shape, into which fuel is introduced from the outside. The outer head <NUM> covers the outer can <NUM> at the front side of the outer can <NUM>. The inner can <NUM> is disposed inside of the outer can <NUM>, and has a hollow cylindrical shape. In addition, the compressed air flows from the rear to the front between the inner can <NUM> and the outer can <NUM>, and fuel and compressed air are injected into the inner can from the front side. Then, as a mixture of the fuel and the compressed air injected into the inner can <NUM> is burned, a high-temperature and high-pressure flame and combustion gas are generated. Here, a space in which combustion takes place inside of the inner can <NUM> is referred to as a combustion chamber <NUM>. The inner head <NUM> is installed at the front side of the inner can <NUM> to mix the supplied fuel with the compressed air and supply the fuel-compressed air mixture to the inside of the inner can <NUM>.

Referring to <FIG>, <FIG> and <FIG>, the inner head <NUM> includes a head plate <NUM> and a plurality of nozzle assemblies <NUM>. The head plate <NUM> covers a front side of the inner can <NUM>. The plurality of nozzle assemblies <NUM> is installed in front of the head plate <NUM> to mix fuel and compressed air and supply the mixture toward the rear side. The nozzle assemblies <NUM> each include a nozzle head <NUM> and a plurality of nozzles <NUM>. The nozzle head <NUM> is spaced apart from the front side of the head plate <NUM>, and fuel is introduced into the nozzle head <NUM>. The plurality of nozzles <NUM> may be provided such that front ends thereof are coupled to the nozzle head <NUM> and rear ends thereof are coupled to the head plate <NUM> so as to mix the supplied fuel and compressed air and supply the mixture toward the rear side. According to the invention, the nozzles <NUM> are formed in a shape that decreases and then increases in diameter from the front side to the rear side.

Referring to <FIG> and <FIG>, according to an embodiment, the plurality of nozzle assemblies <NUM> may be arranged such that one nozzle assembly is disposed at the center portion of the head plate <NUM> and the remaining nozzle assemblies <NUM> are disposed radially around the central nozzle assembly <NUM>. In addition, the plurality of nozzles <NUM> may be arranged such that one nozzle is disposed at the center portion of the nozzle head <NUM> and the remaining nozzles <NUM> are disposed radially around the nozzle <NUM> disposed at the center portion of the nozzle head <NUM>.

Referring to <FIG>, <FIG>, the nozzle head <NUM> is formed in a hollow plate shape so that fuel is introduced from a front side thereof. According to an embodiment, the nozzle <NUM> each may include a nozzle decreasing part <NUM>, a nozzle increasing part <NUM>, a nozzle inlet part <NUM>, and a nozzle connection part <NUM>.

The nozzle decreasing part <NUM> has a diameter, that decreases toward the rear side (i.e., toward the downstream side of the flow direction), is disposed inside of the nozzle head <NUM>, and has fuel holes through which the fuel introduced into the each nozzle <NUM> is supplied into the nozzle decreasing part. The fuel holes <NUM> may be provided to be spaced apart from each other in a circumferential direction of the nozzle decreasing part <NUM>. According to an embodiment, the nozzle increasing part <NUM>, that is disposed on the rear side of the nozzle decreasing part <NUM>, may be supplied with fuel and compressed air from the front side, and may be coupled to the head plate <NUM> between the nozzle head <NUM> and the head plate <NUM>. The nozzle increasing part <NUM> may have a diameter that increases toward the rear side.

The nozzle inlet part <NUM> is connected to the front side of the nozzle decreasing part <NUM>, may protrude forward of the nozzle head <NUM> (i.e., toward the upstream side of the flow direction), may have a constant diameter in a front-rear direction, and transfers the compressed air introduced from the front side to the nozzle decreasing part <NUM>. According to an embodiment, the nozzle connection part <NUM> is connected to the nozzle decreasing part <NUM> and the nozzle increasing part <NUM> and located therebetween, supplies fuel and compressed air from the nozzle decreasing part <NUM> to the nozzle increasing part <NUM>, and may have a constant diameter in the front-rear direction.

The nozzle increasing part <NUM> is provided with air through-holes <NUM> through which compressed air is radially introduced from the outside to the inside thereof. The air through-holes <NUM> are spaced apart from each other in the circumferential direction of the nozzle increasing part <NUM>. In addition, the air through-holes <NUM> may be provided in a plurality of rows spaced apart from each other in the front-rear direction, that is, along a flow direction of a fluid flowing inside of the nozzle increasing part <NUM>. The air through-holes <NUM> each may be formed in a radially inclined shape along the circumferential direction from the outside to the inside of the nozzle increasing part <NUM> so that the compressed air supplied into the nozzle increasing part <NUM> swirls.

Referring to <FIG>, the compressed air introduced forward of the nozzle assembly <NUM> through the space between the inner can <NUM> and the outer can <NUM> flows to the front side of the nozzle inlet part <NUM> and then to the nozzle decreasing part <NUM>. Further, the fuel flows into the outer can <NUM> from the outside, and then flows into the nozzle head <NUM>. It is noted that a pipeline for supplying fuel from the outside to the nozzle head <NUM> is omitted from the drawings. The fuel introduced into the nozzle head <NUM> is supplied into the nozzle decreasing part <NUM> through the plurality of fuel holes <NUM>. Then, the fuel and the compressed air are mixed in the nozzle decreasing part <NUM> and then supplied to the nozzle increasing part <NUM> through the nozzle connection part <NUM>.

Referring to <FIG>, since the diameter of the nozzle decreasing part <NUM> gradually decreases toward the rear side, a flow of the compressed air in the nozzle decreasing part <NUM> converges radially inwards in the nozzle decreasing part <NUM>. Then, a flow rate of the compressed air in the nozzle decreasing part <NUM> increases as the compressed air flows toward the rear side of the nozzle decreasing part <NUM>. Further, according to an embodiment, the fuel may be supplied to such a portion where the flow rate of the compressed air increases. In this case, it is possible to prevent the flashback from occurring on the inner circumferential surface of the nozzle decreasing part <NUM>.

Referring to <FIG>, the fuel-compressed air mixture supplied to the nozzle increasing part <NUM> is supplied to the rear side, passes through the head plate <NUM> and then is injected into the combustion chamber <NUM>. At this time, a portion of the compressed air supplied to the front side of the head plate <NUM> through the space between the inner can <NUM> and the outer can <NUM> may be introduced into the nozzle increasing part <NUM> from the outside of the each nozzle <NUM> through the plurality of air through-holes <NUM>. The air through-holes <NUM> each may be formed in a radially inclined shape along the circumferential direction from the outside to the inside of the nozzle increasing part <NUM> so that the compressed air supplied into the nozzle increasing part <NUM> swirls.

In the internal space of the nozzle decreasing part <NUM>, the central portion thereof may have a fuel-to-air ratio relatively lower than that of a portion adjacent to the inner circumferential surface. That is, in the internal space of the nozzle decreasing part <NUM>, the fuel-to-air ratio increases from the central portion to the portion adjacent to the inner circumferential surface. This is because fuel is supplied to the inner circumferential surface of the nozzle decreasing part <NUM> through the plurality of fuel holes <NUM>. In the internal space of the nozzle increasing part <NUM>, the fuel-to-air ratio may increase and then decrease from the central portion to the portion adjacent to the inner circumferential surface. This is because, contrary to the nozzle decreasing part <NUM>, in the nozzle increasing part <NUM>, compressed air, not fuel, is supplied to the inner circumferential surface.

Therefore, since the portion adjacent inner circumferential surface of the nozzle increasing part <NUM> has a relatively large air-to-fuel ratio, it is possible to prevent the flashback from occurring. In addition, since a swirl is formed in a flow of compressed air flowing into the nozzle increasing part <NUM> through the plurality of air through-holes <NUM>, fuel and the compressed air in the nozzle increasing part <NUM> can be mixed more uniformly and effectively, and the inner circumferential surface of the nozzle increasing part <NUM> can be protected from a flame generated in the combustion chamber <NUM>. When the compressed air flowing into the nozzle inlet part <NUM> is referred to as primary compressed air and the compressed air flowing through the air through-holes <NUM> is referred to as secondary compressed air, due to the influence of the inner recirculation generated by the swirl by the secondary compressed air, a problem may occur that a flame at the central portion of the each nozzle <NUM> is introduced into the nozzle section, in other words, to the direction of the nozzle inlet part <NUM>. This problem may be prevented by the configuration that allows the central portion of the each nozzle <NUM> to maintain a low fuel/air ratio and the air recirculation region in the the each nozzle <NUM> to be pushed back, with an axial velocity of the primary compressed air at the central portion of the each nozzle <NUM>.

Referring to <FIG>, in an exemplary embodiment of the present invention, each of the fuel holes <NUM> may be formed along the radial direction of the nozzle decreasing part <NUM>, that is, orthogonal to a direction of a fluid flowing around the central portion in the internal space of the nozzle decreasing part <NUM>. Referring to <FIG>, in another embodiment of the present invention, the fuel holes <NUM> may each be formed to be inclined rearwards on the basis of the direction of compressed air flowing in the nozzle decreasing part <NUM> as it goes from the outside to the inside of the nozzle decreasing part <NUM> in the radial direction.

Claim 1:
A combustor (<NUM>) configured for mixing compressed air supplied from a compressor (<NUM>) with fuel and combusting the compressed air-fuel mixture, the combustor (<NUM>) comprising:
an outer can (<NUM>) into which the fuel is introduced from the outside;
an outer head (<NUM>) disposed on a front side of the outer can (<NUM>);
an inner can (<NUM>) disposed inside of the outer can (<NUM>) so that the compressed air flows between the inner can (<NUM>) and the outer can (<NUM>), the inner can (<NUM>) having a combustion chamber (<NUM>) for combusting a mixture of the fuel and the compressed air therein; and
an inner head (<NUM>) disposed in front of the inner can (<NUM>) to mix the fuel and the compressed air and supply the mixture into the inner can (<NUM>), the inner head (<NUM>) comprising:
a head plate (<NUM>) covering a front side of the inner can (<NUM>); and
a plurality of nozzle assemblies (<NUM>) disposed in front of the head plate (<NUM>) to mix the fuel and the compressed air and supply the mixture rearwards, the nozzle assemblies each comprising:
a nozzle head (<NUM>) formed in a hollow plate shape so that the fuel is introduced from a front side thereof into the nozzle head (<NUM>); and
a plurality of nozzles (<NUM>) each arranged such that a front side thereof is coupled to the nozzle head (<NUM>) and a rear side thereof is coupled to the head plate (<NUM>) so as to mix the fuel and the compressed air and supply the mixture rearwards, wherein each nozzle (<NUM>) comprises a nozzle decreasing part (<NUM>) disposed inside of the nozzle head (<NUM>) and having a diameter decreasing toward a rear side thereof, with fuel holes (<NUM>) formed through which fuel introduced into the each nozzle (<NUM>) is supplied into the nozzle decreasing part (<NUM>), so that each nozzle has a shape with a diameter decreasing and increasing toward the rear side thereof.