JPS6060424A - Catalytic combustion apparatus - Google Patents

Abstract

PURPOSE:To manufacture a gas-turbine catalytic combustion apparatus having high performance by combining a catalyst having excellent ignitionability at a low temperature and a catalyst having superior durability at a high temperature. CONSTITUTION:A catalyst, which consists of CaO, Al2O3 and NiO and SiO2 therein is brought to 0.5% or less, is formed in honeycomb structure, and the precious metal, such as Pt, Pd, etc. is carried, thus obtaining a catalyst having high activity and excellent stability at a high temperature (1,000-1,200 deg.C). The catalyst has high material stability at the high temperature when the precious metal is not added, but activity is not sufficient. However, the catalyst is used because high activity is improved considerably by adding a small amount of Pt. With the catalytic combustion apparatus for a gas turbine, its durability is improved largely while holding low-temperature ignitionability, and the generation of NOx, etc. is also reduced.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a gas turbine combustor, and more specifically, the present invention relates to a gas turbine combustor, and more specifically, a gas turbine combustor that has a small amount of nitrogen oxides (hereinafter referred to as NOx) generated during combustion and has good combustion efficiency. The present invention relates to a gas turbine catalytic 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, for example, in gas turbines and the like, it is desired to burn fuel at as high a temperature as possible.

However, in the conventional method, a mixture of fuel and air is ignited using a spark plug or the like to cause vapor phase combustion, and therefore, there are parts of the combustor that have a high temperature of over 200 υ°C. It is known that a large amount of nitrogen oxidation (NOx) is generated in this high temperature section, causing problems such as environmental pollution.

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 and the upper temperature limit at which NOx is generated is 1500°C.
The combustion temperature can be increased to a certain degree.

However, when the above-mentioned catalytic combustion method is applied to a gas turbine, the combustion catalyst is required to have two contradictory characteristics, namely, low-temperature ignitability and heat resistance. In gas turbines currently in use, combustion air is preheated to about 300° C. and then introduced into the combustor using a compressor blower. The flame-combusted air-fuel mixture is then cooled to about 1200° C. and then sent into the turbine. Therefore, when a combustion catalyst filling part is installed in a gas turbine combustor, the combustion catalyst is required to ignite the fuel gas at a temperature of about 300°C and to withstand a temperature of about 1200°C caused by the combustion gas. will be done.

As the combustion catalyst for gas turbines described above, platinum (Pt
) type catalyst, palladium (Pd) type catalyst, or a noble metal type catalyst such as an alloy type catalyst thereof. As such a noble metal catalyst, for example, as shown in FIG. 1, a surface-thermal J1. ! γ-alumina (γ-A, 72
0s) A coating layer 2 is provided, and a noble metal catalyst 3 is coated using a dipping method or the like.
There are known products that carry .

A conceptual diagram of a catalytic combustor using these catalysts is shown in FIG. In FIG. 1, after the fuel injected from the primary combustion fuel nozzle 4 is combusted, the fuel from the secondary fuel nozzle 5 and combustion air 7 are mixed, catalytic combustion occurs in the catalyst 9, and the It is injected into the turbine from the bill nozzle 8. As mentioned above, the problem with such a combustor is the low-temperature ignition performance and heat resistance of the catalyst, but at present no one has been obtained that fully satisfies these requirements.

[Purpose of the invention]

An object of the present invention is to provide a high-performance gas turbine catalytic combustor that combines a catalyst with excellent ignitability at low temperatures and a catalyst with excellent durability at high temperatures.

[Summary of the invention]

As a result of extensive research into catalysts for catalytic combustion, the present inventors found that the one with the best ignition characteristics at low temperatures when using natural gas as fuel is a coating of γ-alumina on a honeycomb structure. It has become clear that a layer is provided to support a noble metal mainly composed of Pd. Since these catalysts have low heat resistance, conventionally, rare earth oxides such as Oe have been added to improve heat resistance. As a result of repeated improvements to these catalysts, we have found that the addition of oxides such as Oe poses a problem in durability when used at temperatures of 800 to 1000°C.

This is because when Oe etc. reach a high temperature of about 1000℃, Pd
It was thought that the catalytic activity of Pd was reduced by bonding with other noble metals. Therefore, we found that La and Nd, which have low reactivity such as Pd, are preferable instead of Oe.
It has been found that addition of other rare earth elements is not preferable.

Furthermore, it has been found that if 5I02 is contained in alumina used for the coating layer, it will bond with noble metals at high temperatures, resulting in a similar decrease in activity. Therefore, we prototyped a catalyst whose main component was alumina containing virtually no Sin in the coating layer, with the addition of La or Nd, as well as a cylindrical metal layer mainly composed of Pd. It has also become clear that it has excellent ignitability and durability at low temperatures.

However, even if a combustor was constructed using only this catalyst, it was difficult to completely burn methane.

In addition, when using easily combustible fuel such as propane, complete combustion was possible in the initial stage, but since the temperature of the catalyst rose to over 1000°C in the latter half, deterioration in the latter half was severe, making it impractical. Ta. This means that at high temperatures of 1000℃ or higher,
This is because the catalyst coating layer deteriorates.

Therefore, as a result of further research into a stable catalyst with higher surface thermal properties, that is, a catalyst in the latter stage of the catalytic combustor, we achieved our goal by further improving the catalyst developed for high-temperature steam refueling. That is, OaO
, A403. A catalyst consisting of NiO and SiO2 of less than 0.05 cm is formed into a honeycomb structure, and a high temperature (100 (1 to 1
We were able to obtain a insect pollutant with high activity and excellent stability at 200C. Is this catalyst Pt? When any precious metal is added, the material stability at high temperatures is high, but the activity is not sufficient, but by adding a small amount of Pt, the activity is increased several times.

This catalyst is OaO in which the honeycomb structure itself has a catalytic effect.
, A1203, and NiO, and does not have the conventional γ-alumina coating layer, so there is no reduction in activity due to deterioration of this.

Here, the present invention will be explained in detail by way of examples.

[Embodiments of the invention]

Three types of catalysts (A, H, O) were prototyped. Catalyst A is a single catalyst, but contains Ce in the coating layer, and 2% of 5i02 is contained in the alumina of the coating layer. Catalyst B is a catalyst used in the present invention, and is a Pd-based catalyst, but La is used instead of Ce, and 5in2 in the coating layer is 0.05% or less. Catalyst 0 is CaO used in the present invention
, Al2O, and NiO, with 0.5% or less of 5i02 and 1% of Pt supported. Experiment 1 used a combustor filled with 10 crn of catalyst A, Experiment 2 used a combustor filled with 10 crn of catalyst B, and Experiment 3 used a combustor filled with 5 crn of catalyst A in the front stage and 5 crn of catalyst C in the latter stage. Experiment 4 was conducted using a combustor according to the present invention in which 5 parts of catalyst B were filled in the front stage and 5 parts of catalyst C were packed in the latter stage.

The combustor uses a small device of 25 mm for actual inspection, and the flow rate is 2.
The catalyst inlet gas temperature was 450°C. The fuel was natural gas (mainly methane). Natural gas was mixed with 3 parts of air. Figure 3 shows the change in combustion efficiency over time for each experiment. In FIG. 3, a is the result of experiment 1, b is the result of experiment 2, C is the result of experiment 3, and d is the result of experiment 4. As shown in FIG. 3, in Experiments 1 and 2, the combustion efficiency was poor from the beginning, and in Experiment 3, although the initial combustion efficiency was good, the efficiency decreased with time. Experiment 4 showed stable combustion efficiency over a long period of time.

This shows that the catalytic combustor of the present invention is superior to the conventional one.

〔Effect of the invention〕

The catalytic combustor for gas turbines of the present invention maintains low-temperature ignitability and has significantly improved durability compared to conventional ones. Therefore, it is possible to save and use energy efficiently, and since it is possible to burn it without generating NOx or the like, it does not cause problems such as environmental pollution.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the structure of a conventional noble metal combustion catalyst.
FIG. 2 is a conceptual diagram of a catalytic combustion type gas turbine combustor, and FIG. 3 is an explanation showing a comparison between the combustor of the present invention (d) and a conventional combustor (ac). It is a diagram. Honeycomb structure, 2. Assisted layer, 3. Precious metal catalyst particles, 4. Primary fuel nozzle, 5. Secondary fuel nozzle, 6.
・Igniter, 7... Combustion air, 8... Nozzle, 9.
・Honeycomb structure catalyst.

Claims (1)

[Claims] (1) When using the catalytic combustion method in the combustor of a gas turbine, the catalyst filling section is configured in two stages, the first stage is filled with a noble metal catalyst containing at least Pd, and the second stage is filled with OaO
, A40. ,, It is characterized by using a catalyst containing NiO as a main component with the addition of noble metals, and the coating layer of the medium is Al! 0
1 as the main component, S i 02 is 05 or less, and La
, at least one type of Nd is Ni075 (10
% or more, A), 0. d: 2 I) ~70%, ca
. is 20 to 60f) and 5iO1 is 0.5% or less, and precious metals such as Pd-Pt are added to the honeycomb structure in the amount of 0.1 to
A catalytic combustor characterized in that the catalyst is supported by 0.1 to 1% of the three catalysts.