JPS60200021A - Combustor of gas turbine - Google Patents

Abstract

PURPOSE:To reduce NOX by improving low-temperature ignitability and high activity, by so constituting the titled combustor that three kinds of catalysts having different predetermined composition are arranged in order according to a flow of an air-fuel mixture, in a catalytic combustion type gas turbine combustor. CONSTITUTION:A first stage - thrid stage catalysts 4-6 are arranged from the upper stream to the lower stream against a flow 9 of a mixture of air 8 and fuel. As for the first stage catalyst 4, it is made into the catalyst to be obtained by providing a coated layer 2a formed of alumina containing palladium 3a or platinum 3b and cerium on a heat resisting carrier 1, as for the second stage catalyst 5, it is constituted by providing similarly a coating layer 2b containing selected article out of zirconium, strontium and barium as a metal in place of the cerium on the carrier 10, and as for the third stage catalyst 6, it is constituted by providing a coating layer 2c containing the selected article out of lanthanum and neodymium. With this constitution, low-temperature ignitability, high activity and life are improved and generation of NOX can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas turbine combustor using a catalytic combustion method.

[Technical background of the invention and its problems]

In recent years, with the depletion of petroleum resources and the like, in order to use energy resources efficiently, it has become desirable to burn fuel at as high a temperature as possible in, for example, gas turbines.

However, the conventional method is to ignite and burn a mixture of fuel and air using a spark plug or the like.
Inside the combustor, there is a high temperature area that partially exceeds 2000°C. It is known that a large amount of nitrogen oxides (NOx) is generated in this high-temperature section, causing environmental pollution and other problems.

In order to solve these problems, a catalytic combustion method has been proposed in which a mixture of fuel and air is combusted using a catalyst. According to this combustion method, uniform combustion is possible,
Moreover, the combustion temperature can be raised to about 1500° C., which is the upper limit temperature at which NOx is not generated.

However, when the above-mentioned catalytic combustion method is applied to a gas turbine, two contradictory characteristics are required of the combustion catalyst, namely, low-temperature ignitability and heat resistance. In gas turbines currently in practical use, the combustion air is heated to a temperature of 300°C.
After being preheated to a certain degree, it is introduced into the combustor using a compressor blower. Then, the flame-combusted combustion gas is cooled to about 1200° C. and then sent into the turbine. Therefore, in a gas turbine combustor, the combustion catalyst is required to ignite the mixture at a temperature of about 300°C and to withstand a temperature of about 1200°C due to combustion gas.

As the above-mentioned combustion catalyst, it is possible to use a noble metal catalyst such as platinum (pt). For example, as shown in FIG. 1, such a noble metal-based catalyst may include a heat-resistant carrier 1 having a mechanical strength of -1, and a coating layer 2 of γ-alumina (γ-AI403) as an active carrier. , those in which noble metal particles 3 are supported by a dipping method or the like are known.

However, for such noble metal catalysts, those whose ignition temperature is usually 300°C or lower are said to have a heat resistance temperature of 600°C or lower, and their catalytic activity rapidly decreases at higher temperatures. This has the problem that it is not suitable for practical use.

The reason why the catalyst activity rapidly decreases at temperatures of 600° C. or higher can be considered as follows.

First, the noble metal particles on the surface of the active carrier aggregate and become coarse due to heat transfer, which reduces the catalyst surface area and lowers the combustion performance. Then, when the second C1゛γ-At, 03 is at a temperature from around 1000°C to above, α-Az
Due to the phase transition to 3os, cracks occur within the coating layer or between the coating layer and the heat-resistant carrier, and the coating layer peels off together with the catalyst metal (two possible causes).

Therefore, in order to improve the heat resistance of noble metal combustion catalysts, for example, γ-At20. In the coating layer, the entire coating layer is improved, and the noble metal particles on the γ-8 to 03 coating layer are
Attempts have been made to prevent agglomeration due to heat transfer by adsorbing 40 g of -AI + divalent material, and to prevent the formation of cracks by preventing 140 g of γ-A from becoming alpha.

For this reason, many attempts have been made to add many metals, including rare earths, to the γ-At203 coating layer, and some are being put into practical use in automobile catalysts, etc. There is no example of a catalyst exhibiting and sustaining catalytic performance for a long time at temperatures exceeding ℃.

[Purpose of the invention]

The purpose of the present invention is to have excellent low temperature ignition property ζ2 and 600 to 1
An object of the present invention is to provide a gas turbine combustor that is equipped with a catalyst that has high activity and long life even in a temperature range of 200° C., and in which the generation of NOx is significantly reduced.

[Summary of the invention]

In view of the above-mentioned current situation, the inventors of the present invention have conducted intensive studies on catalysts that can be used even at high temperatures of 600°C or higher, and as a result, they have determined that the relationship between alumina containing all types of metals and precious metals at high temperatures has been determined. The present invention was achieved by discovering a catalyst that has unique activity in the temperature range required for catalysts used in gas turbine combustors.

In the catalytic combustion type gas turbine combustor according to the present invention, the combustion catalyst is composed of three different types of catalysts as shown in FIG. Mix to form a mixture, and then add the first stage catalyst 4
, second-stage catalyst 5, and third-stage catalyst 6 (: are further combusted to become combustion gas 9 and flow out to the turbine. 6
2. Palladium (Pa) 3 a or platinum (pt) 3
The structure includes first, second and third coating layers 2a, 2b and 2Ct made of alumina containing b, in which metal added to the first, second and third coating layers is The type is cerium (Ce) in the first coating layer,
The second coating layer is characterized by at least one of zirconium (Zr), strontium (Sr), and barium (Ba), and the third coating layer is at least one of lanthanum (LJ&) and neodymium (Nd). There is. Also, is the arrow in the figure the flow direction of the mixture? show. The heat-resistant carrier used in the present invention may be any carrier as long as it has stable properties even in a high-temperature oxidizing atmosphere of about 1200°C; specific examples thereof include:
Examples include ceramic supports such as cordierite, mullite, α-alumina, zirconia spinel, and titania. The shape may be a pellet shape, a honeycomb shape, etc., but a honeycomb shape is particularly preferred since it is advantageous in terms of pressure loss and the like. These first. The second and third stage catalysts may be installed successively as shown in FIG. 2, or they may be installed at intervals depending on conditions.

Further, as the air mixed with the fuel, an oxidizing gas such as concentrated oxygen may be used in some cases, or nitrogen or other essential carbon dioxide may be further diluted with an inert gas. You can leave it there.

As the alumina provided on the heat-resistant carrier, for example, γ-alumina is preferable because it has a function as an active carrier. Furthermore, the type of metal according to the present invention added to the coating layer is selected as one that exhibits the highest activity under the temperature conditions in which the catalyst containing the metal is used. V 1st stage catalyst: 800°C or less, 2nd stage catalyst: 1000°C or less, 3rd stage catalyst: 1200°C or less
Used below ℃. When used at temperatures exceeding the respective ranges, the catalyst activity decreases rapidly.

Furthermore, the first. The total amount of metal added to the second and third coating layers is approximately A/40. l
The amount is preferably 5 to 30% by weight, and 10 to 2% by weight.
It is more preferable that the amount is 0% by weight. If the amount of the added metal is less than the above range, no improvement in heat resistance will be observed, while if it is more than 0%, the oxide of the added metal will This is because a large amount of 403 precipitates at the grain boundaries, reducing the strength of the coating layer.

The noble metals used in the present invention are particularly selected from palladium and platinum due to economic conditions. Noble metal alloys (Pd-Rh,
It is desirable to use Pt-Rh, Pd-8i, Pt-8t, etc.). The amount of noble metal supported is not particularly limited, but from the viewpoint of catalytic activity, it is 0.1 to 10% of the total weight of the catalyst.
Preferably, it is r/l.

The catalyst used in the gas turbine combustor according to the present invention described above can be manufactured, for example, as follows.

First, noble metals and various additive metals are added to an alumina coating composition consisting of alumina sol or γ-At, O,
For example, a predetermined amount of these metals is added in the form of metal salts such as chlorides or nitrates.

Next, the above composition is mixed using, for example, a ball mill. The coating liquid obtained in this way is
The coating liquid is coated by pouring onto a heat-resistant carrier or by immersing the heat-resistant carrier in a coating liquid, and after sufficiently drying at room temperature, it is fired at, for example, 650° C. for about 3 hours.

Furthermore, the catalyst used in the gas turbine combustor of the present invention can be obtained by firing at 550° C. for about 3 hours in a hydrogen atmosphere, for example.

The reason why the catalyst used in gas turbine combustor C2 of the present invention has excellent heat resistance is not clear, but it can be considered as follows.

That is, as shown in FIG. 3, precious metals such as Pd 3a and Pt
It is thought that heat transfer of the noble metal is inhibited because 3b is contained in At and 03.

In addition, γ-At! When using 03, γ-AZ,
O = metal added to the coating layer (Ce, Zr, Sr, B
a, La, Nd) are α-At203 of γ-Atko03
γ-At, 0. Since it has the effect of completely refining the grain boundaries of the coating layer, it is thought that the generation and propagation of high heat of the combustion catalyst is prevented.

[Embodiments of the invention]

Example 1 An alumina coating composition having the composition shown below was prepared.

Alumina sol (solid content 80%) 125r Cerium nitrate 25f Palladium chloride 10f The above composition was mixed at room temperature for 2 hours using a ball mill to obtain an alumina coating composition.

Next, the alumina composition was completely applied to a cordierite honeycomb carrier (1) by pouring a liquid obtained by dispersing the alumina coating composition in water, and then dried at room temperature for about one day. ℃ for 3 hours, and then fired at 550℃ for 3 hours in a hydrogen atmosphere to obtain a catalyst (4)'f for a gas turbine combustor according to the present invention.
! :Obtained.

Using the same method, alumina coating compositions with different noble metals and additive metals were prepared to obtain 8 filts of catalyst (B) and catalyst (I) as shown in Table 1. Ta. At the same time, as a comparative example, six types of catalysts (catalyst (f)) were added to catalyst (a), which was installed outside the above range, in Table 1 (=all types and amounts of precious metals and additive metals as shown) using the same method. The above catalyst prisoner to catalyst (I
) and catalysts (a) to (f) '(r) were aged in an electric furnace at a total aging temperature of 800°C, 1000°C, and 1200°C, respectively, and then their catalytic properties were evaluated using a flow test device. The test conditions were as follows:
Gas flow rate: 544r+in, combustion gas concentration: methane (
CH4)i%vcatalyst-)i:1Qcc and space velocity; 3 x 10' hr=, and the catalyst activity was measured at a catalyst temperature of 300°C. From the results shown in Table 1, in the temperature range up to 800℃, Pd-Ce, IQQQ
It can be seen that Pd- (at least one of Sr, Ba, and Zr) is a desirable catalyst up to 1200°C, and Pt- (at least one of La and Nd) is a desirable catalyst. Table 1: All of the above catalysts were combined as shown in Table 2 to form a combustion catalyst, filled into a gas turbine combustor, and the gas turbine combustor was operated. And the combustion efficiency is 99.9% or more, and the combustion is NNOx3 in the gas.
Judgment was made based on two criteria: pp or less. As a result, the second
As shown in the table, only the examples in which catalysts according to the present invention were appropriately combined passed the judgment, and other comparative examples outside the scope of the present invention (2) were, for example, comparative example (1) with only precious metals Pd and pt, and Comparative example (2) using the catalyst included in the addition amount J6' all failed as they did not satisfy the above criteria.Also, the catalyst temperature during combustor operation was 700 °Ct in the first stage.
The second stage was 00℃, and the third stage was 1100℃.

As is clear from Table 2, the gas turbine combustor according to the present invention has a high combustion efficiency as a gas turbine combustor by appropriately combining three types of catalysts that exhibit unique activities in the temperature range in which it is used (1). It was confirmed that the catalyst of the present invention is significantly superior to that of the comparative example. Therefore, it can be used in a wide temperature range with high heat resistance while maintaining its characteristic low-temperature ignitability.In order to use each catalyst in a temperature range that maintains its high activity,
Deterioration is greatly reduced and it has a long life.

In the above example, three types of catalysts are used, but this is used when generating combustion gas exceeding 1200C, such as in a gas turbine, and when generating all combustion gas below 1000℃, this catalyst is used. Of the catalysts of the invention, a two-stage catalyst used on the low temperature side may be used.

In addition, since the temperature of the catalyst changes slightly depending on combustion conditions, it is generally necessary to control the temperature to 800°C in the first stage, 1000°C in the second stage, and 1200°C in the third stage. In the case of combustion, the length of the catalyst can be adjusted.

〔Effect of the invention〕

The gas turbine combustor of the present invention has significantly improved heat resistance and long life while maintaining low-temperature ignition performance compared to conventional combustors using noble metal combustion catalysts. . Therefore, it is possible to save and use energy efficiently, and since it is possible to burn it with almost no generation of NoX etc., it does not cause problems such as environmental pollution.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the structure of a conventional noble metal combustion catalyst, Fig. 2 is a cross-sectional schematic diagram showing the structure of a gas turbine combustor according to the present invention, and Fig. 3 is a schematic diagram showing the structure of a combustion catalyst. Schematic percentage formula showing the structure of different types of catalysts% 6...Third stage catalyst 7...Fuel nozzle 8...Air 9...Combustion gas agent Patent attorney Noriyuki Chika (and 1 other person) No. 1
Figure 2 Figure 3 Figure f 2y / a+ / Zc

Claims (3)

[Claims] (1) In a gas turbine combustor that burns a mixture of fuel and air using a catalytic combustion method, the combustion catalyst of the gas turbine combustor has three types of catalysts: a first stage catalyst, a second stage catalyst, and a third stage catalyst. A first stage catalyst comprising different catalysts and located upstream of the flow of the mixture comprises a catalyst having a first coating layer made of alumina containing a noble metal and cerium on a heat-resistant carrier; The two-stage catalyst includes a second coating layer made of alumina containing a noble metal and at least one metal of zirconium, strontium, and barium on a heat-resistant carrier, and a third coating layer located further downstream. A gas turbine combustor characterized in that the stage catalyst comprises a heat-resistant carrier provided with a third coating layer made of alumina containing a noble metal and at least one of various metals such as lanthanum and neodymium. (2) The upper limit temperature for use of the first stage catalyst is 800°C, and the upper limit temperature for use of the second stage catalyst is 1000°C;
The gas turbine combustor according to claim 1, wherein the upper limit temperature for use of the third stage catalyst is 1200°C. (3) Claim 1 characterized in that the noble metal used in the first stage catalyst and the second stage catalyst is palladium, and the noble metal used in the third stage catalyst is platinum.
The gas turbine combustor described in Section 1.