Fuel lance for a gas turbine plant and a method of operating a fuel lance

Translation of description of equivalent WO 2007113074 A1

DESCRIPTION

FUEL LANCE FOR A GAS TURBINE SYSTEM AND A

METHOD FOR OPERATING A FUEL LANCE

TECHNICAL FIELD

p0005The present invention relates to the field of the art of gas turbine plants. It relates to a fuel lance for a gas turbine plant and a method for operating such a fuel lance.

STATE OF THE ART

p0007Combined cycle power plants with integrated gasification (IGCC Integrated Gasification Combined Cycle) are normally operated with a synthetic fuel gas (syngas or MBtu gas), which is produced by gasification of coal, biomass and other fuels. This fuel differs significantly from natural gas for the energy value, the density and the burning characteristics such as flame speed and Zündverzögerungsze with sequential combustion or reheating fd .v_.v> are therefore both in the fuel supply system and in the combustion chambers significant adjustments necessary to deal with these differences.

p0008A gas turbine plant with reheating with its essential components is shown in Fig. 1 schematically. The gas turbine system 10 of FIG. 1 comprises a means for compressing the sucked combustion air, which is composed of a low pressure compressor 11a and a downstream high pressure compressor 11 b. The compressed combustion air is to a first combustion chamber 12 where it is partially used for the combustion of a supplied via a first fuel supply 23 fuel. The resulting hot gas is expanded in a subsequent high-pressure turbine 13, performing work, and then a second combustion chamber 14 is supplied, in which the unconsumed portion of air is used for combustion of a supplied fuel via a second supply 23 fuel. The coming out of the second combustion chamber 14 hot gas is expanded in a subsequent low-pressure turbine 15, performing work and then passed through a heat recovery steam generator (heat recovery steam generator HRSG) 21 conducted where steam (not shown) for steam turbines of a separate water-steam cycle generates becomes. The exhaust gas 22 may then be supplied to a fireplace. The two turbines 13 and 15 are connected via a shaft 20 with the compressors 11a, b and a generator 16 for electric energy and drive them to. may be selected from the compressors 11a and 11b for cooling purposes diverted compressed air in the corresponding high-pressure or low pressure once-through coolers (OTC) cooled 18 and 19, and then to cooling to the combustion chambers 23, 24 and turbine 13 are passed 15th A comparable gas turbine system is disclosed for example in US-A-5,617,718. In the second combustion chamber of the sequential Verbrennunc eingedübi means of a fuel lance in the hot gas stream, _^^i_^n ■ w _{u ^}ι

p0009Fig. 2 of US-A-5,617,718 is indicated, and the structure of which is shown for example in EP-A2-0 638 769 in detail. When comparing different types of syngas with natural gas, it turns out that for the syngas, depending on type and origin, a larger flow cross-section is needed, which may be greater by a factor of 3 to 9 as the flow cross section for gas. Currently, there is a major challenge, the large volume flows with syngas associated with the fuel lance to inject into the combustion chamber. Theoretically, it is possible to enlarge the lance diameter to provide the needed additional space. This, however, would have a significant impact on the aerodynamics of the burner and draw a new design of the combustion chamber and the housing of the gas turbine to be. It is therefore desirable to keep the outside diameter of the fuel lance at the transition from natural gas to syngas constant. On the other hand, some changes are necessary to reduce the residence time of the syngas within the mixing zone of the burner, thus avoiding a flashback.

SUMMARY OF THE INVENTION

p0011It is an object of the invention to provide a fuel lance and a method for its operation that allow, without significant changes in the outer dimensions of the use of syngas as fuel in the second combustion stage of a gas turbine with sequential combustion.

p0012The object is solved by the totality of the features of claims 1, 8 and 12. FIG. For the inventive solution is essential that the first injection openings are arranged directly at the lance tip, and that the first injection openings are oriented such that the emerging from them fuel jets with the lance axis form an acute angle. By shifting the injection openings in The flow direction of the hot gas to the tip of the lance for

p0013Skew tilting the injected Brennstoffstrarw

p0014Flow direction, the residence time of the syngas is reduced in the mixing zone. The (top) angle that enclose the beams with the lance axis, is a parameter that can be optimized as a function of hydrogen content of the fuel, wherein the angle is less than the more, the higher the proportion of hydrogen.

p0015According to one embodiment of the invention is rounded the lance tip, and placed the first injection openings in the rounding.

p0016Another embodiment is characterized in that the intermediate tube ending at a distance from the lance tip and at the end an opening, which corresponds to the length of the tube.

p0017A further embodiment is characterized in that in the intermediate tube concentrically an inner tube is arranged so that the inner tube is guided to the lance tip, and that second injection openings are provided for the injection of liquid fuel at the lance tip, which supplies through the inner tube with the liquid fuel will.

p0018Preferably, the first and second injection openings are each arranged on a common radius around the lance axis, wherein the radius of the second injection openings is smaller than the radius of the first injection openings.

p0019The second injection openings can thereby be designed to produce a fuel jet. but they can also be adapted to produce a spray.

p0020According to the inventive method for operating a fuel lance without inner tube in the intermediate tube syngas as fuel to the first guided injection openings and injected through the first Eindüsu hot gas flow.

p0021An embodiment of the inventive method is characterized in that in the intermediate space between the outer tube and the intermediate tube likewise guided syngas as fuel to the first injection openings and is injected by the first injection openings into the hot gas stream.

p0022Another embodiment is characterized in that in the space between the outer tube and the intermediate tube, a diluting medium, in particular nitrogen or steam, led to the first injection openings and is injected through the first injection openings into the hot gas stream.

p0023A further embodiment is characterized in that in the intermediate space between the outer tube and the intermediate tube or air as the carrier

p0024Shielding medium is guided to the first injection openings and injected through the first injection openings into the hot gas stream.

p0025According to the inventive method for operating a fuel lance with inner tube is in the space between the intermediate pipe and inner pipe is guided to the first injection openings as a fuel syngas and injected through the first injection openings into the hot gas stream, and it is in the inner pipe, a liquid fuel, in particular oil, to the second guided injection openings and injected through the second injection openings into the hot gas stream.

p0026An embodiment of this inventive method is characterized in that in the intermediate space between the outer tube and the intermediate tube likewise guided syngas as fuel to the first injection openings and is injected by the first injection openings into the hot gas stream. However, it is also conceivable that in the intermediate space between the intermediate pipe a diluting medium, in particular Stickoiwu w_^^i _uαin the_Kι ..U, performed the first injection openings and is injected through the first injection openings into the hot gas stream.

p0027It may furthermore be advantageous if performed in the space between the outer tube and the intermediate tube air as a carrier or shielding medium of the first injection openings and is injected by the first injection openings into the hot gas stream.

p0028However, it is also conceivable that in the intermediate space between the intermediate tube and inner tube out as a fuel, a mixed gas of natural gas and steam or nitrogen to the first injection openings and is injected by the first injection openings into the hot gas stream, and that in the inner pipe, a liquid fuel, in particular oil, to the second

p0029Injection openings is guided and injected through the second injection openings into the hot gas stream.

p0030In particular, can be guided to the first air as the carrier injection openings and injected through the first injection openings into the hot gas stream in the space between the outer tube and the intermediate tube.

BRIEF EXPLANATION OF THE FIGURES

p0032The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it

p0033Figure 1 is a simplified schematic of a gas turbine plant with sequential combustion, as known from the prior art and suitable for the realization of the invention. Figs. 2 and 3 a first embodiment of a combustor

p0034Invention for use with syngas in the ..W_^n_^i, combustion stage of a gas turbine plant according to Fig 1, wherein in Figure 2 exclusively syngas is injected..;

p0035FIGS. 4 to 6 a second embodiment of a burner lance according to the

p0036Invention for use in the second combustion stage of a gas turbine plant according to Fig. 1, wherein outside of the inner tube out different media and injected.

WAYS OF IMPLEMENTING THE INVENTION

p0038In Figs. 1 and 2, a first embodiment of a fuel lance according to the invention is shown, wherein, in the two figures, different modes of operation are illustrated. The fuel lance 25 of FIG. 1 and 2 extends initially vertically into the flow of the hot gas 37 into it, then bends at right angles and extends in the direction of flow of the hot gas 37 along a lance axis 34 which is parallel to the hot-gas flow. The fuel Ia nze 25 comprises an outer tube 26 in which a concentric

p0039disposed intermediate pipe 27th The outer tube 26 is pulled up to the lance tip 38 and ends there with a rounded end, are distributed in the comparatively large injection openings 28 around the lance axis 34 at a radial distance. The intermediate pipe 27 ends before the lance tip 38 with an opening corresponding to the length of the tube. In this way, a medium which is guided in the intermediate tube 27 or in the space between outer tube 26 and intermediate tube 27, are injected through the injection openings 28 in the hot gas flow without problems.

p0040According to FIG. 2 is in a particularly simple embodiment of the invention, the entire space inside the fuel lance 25 for advancing of syngas 29 utilized. An inner tube -. Is used as shown in Figures 4-6 sgd (liquid fuel is completely removed.<img id="imgf000010_0001" he="4" wi="31" file="imgf000010_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> Space between outer tube 26 and intermediate tube 27, which is otherwise used for guiding air, used for the transport of syngas. The injection openings are compared to the known solution of EP-A2-0 638 769 shifted downstream and with its jet direction (dashed lines in Fig. 2, 3) from the radial direction toward the axial direction inclined or tilted to the residence time of the syngas decrease in the mixing zone. The (top) angle the beams enclose with the lance axis 34, is a parameter that can be optimized as a function of hydrogen content of the fuel, wherein the angle is less than the more, the higher the proportion of hydrogen.

p0041This results in the following advantages: - It is the maximum flow cross section for the syngas to

p0042available; and

p0043- For gas injection results in a minimized pressure drop; The operation, however, is limited to a fuel, namely syngas.

p0044In a modification of the operating mode the space between the outer tube 26 and the intermediate tube shown in FIG. 2 27 are used to supply a diluent medium in the form of steam or nitrogen. Alternatively, can be reserved as a carrier or screening current according to FIG. 3, the gap of supply of air 30. Both the dilution and the shield helps to improve the combustion behavior by a better mixing is achieved before the ignition, so that the NOx emissions and the risk of flashback be reduced.

p0045but it is also conceivable, according to FIG. 4 employ a burner lance 31, wherein the 27 concentric with an inner tube 32) is arranged inside of the intermediate tube, through which liquid fuel in the form of oil 35 in the lance tip 38 and there through separate injection openings 33 is injected. The Öleindüsung takes place in the center of the lance tip 38. Gems spaces between outer tube 26 and ZwischenroL ..i un_^ t, .κ, υιιcιι intermediate tube 27 and inner tube 32 out syngas. According to FIG. 5, the space between outer tube 26 and intermediate tube 27 used to either transport a diluent (steam or nitrogen), or - located as shown in FIG. 5 - 30 as a carrier air or shielding current. The injection openings 33 for the oil 35 can be designed either for the production of fuel jets or a spray. Although 32 the place for the syngas is slightly restricted by the introduction of the inner tube, the possibility of additional fuel (back-up fuel) arises as to use.

p0046Finally, it is also conceivable to use natural gas instead of the syngas with 4-5 of the fuel lance of FIG.. Since due to the large injection openings 28 which thus attainable flow rate for natural gas itself is too small, a natural gas operation can be made possible by the fact that produced by dilution of the natural gas with steam or nitrogen, a mixed gas 36 and injected instead of the syngas is (Fig. 6 ). In this way the Eindüsungsgeschwindigkeit of the natural gas can be increased to achieve a better penetration and mixing. In addition, slowing the addition of dilution media such as steam or nitrogen, the

p0047Combustion chemistry, and helps so to a better mixing of fuel and air, and thus an improved emission behavior.

p0048Overall, the results with the invention the following advantages: - A simple and feasible in retrofit solution for Syngasverwendung with sequential combustion in a gas turbine; a maximum flow area and minimum pressure drop, if they are not on the inner tube; and an ideal opportunity for additional fuels (back-up fuel). LIST OF REFERENCE NUMBERS

p004910 gas turbine plant

p005011a low pressure compressor

p005111b high pressure compressor

p005212.14 combustor

p005313 high pressure turbine

p005415 low pressure turbine

p005516 generator

p005617 air inlet

p005718 high-pressure once-through cooler

p005819 low-pressure once-through cooler

p005920 shaft

21 HRSG

p006122 exhaust

p006223,24 fuel supply

p006325.31 fuel lance

p006426 outer tube

p006527 intermediate tube

p006628,33 injection opening

p006729 syngas

p006830 air

p006932 inner tube

p007034 lance axis

p007135 oil

p007236 mixed gas

p007337 hot gas

p007438 lance tip