JPS6066022A - Combustion in gas turbine - Google Patents

Abstract

PURPOSE:To enable to maintain high combustion efficiency for a long period by passing a fuel pipe through a catalyst filling unit. CONSTITUTION:A combustion unit has largely two catalyst filling units. The first catalyst filling unit 7 contains a catalyst including mainly Pd, and the second catalyst filling unit uses a catalyst including mainly Pt. Since the thermal insulating flame temperature of mixture gas of fuel and air supplied to this unit is 800-1,200 deg.C, it is 1,200 deg.C or lower even is a combustion occurs, and noble metal catalyst is less deteriorated. Further, since a fuel pipe 9 is passed through the first unit 7, the catalyst heat exchanged from fuel is not overheated, and the temperature drop when fuel is injected in the first catalyst outlet is advantageously less. As a result that the combustion gas and fuel are mixed at the outlet of the first catalyst, it becomes the temperature and fuel density for effectively acting the second catalyst filling unit, thereby preferably performing a combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas turbine combustion method used in a gas turbine power generation system, and more specifically, to a gas turbine combustion method used in a gas turbine power generation system. The present invention relates to a gas turbine combustion method using a catalytic combustion method that uses a small amount of fuel and has good combustion efficiency.

[Technical background of the invention and its problems]

In recent years, with the depletion of petroleum resources and the like, various alternative energies have been sought, and on the other hand, efficient use of energy resources has been required. Examples of systems that can meet these demands include gas turbines that use natural gas as fuel, steam turbine combined cycle power generation systems, coal gasification gas turbines, and steam turbine combined cycle power generation systems, which are currently being studied.

These gas turbine and steam turbine combined cycle power generation systems have higher power generation efficiency than conventional steam turbine power generation systems that use fossil fuels, so natural gas production is expected to increase in the future. It is expected to be a power generation system that can effectively convert fuels such as coal and gasified gas into electricity.

However, the conventional gas turbine combustor has a problem in that a large amount of NOx is produced due to the presence of a partially high-temperature section. Therefore, a flue gas denitrification device or the like must be provided, which poses problems such as the device becoming complicated.

A homogeneous combustion method (hereinafter referred to as catalytic combustion method) has been proposed. The catalytic combustion method uses a catalyst to combust a mixture of fuel and air.

According to this method, combustion can be started at a relatively low temperature, no cooling air is required, and the amount of combustion air is increased, so the maximum temperature is low and the NO generated
It is possible to make the amount x extremely small.

FIG. 1 is a conceptual diagram of such a catalytic combustion type combustor, in which the catalyst filling portion 7 is filled with a catalyst body having a honeycomb structure.

The catalytic combustion method, which is an excellent method for this purpose, also has drawbacks. That is, the noble metal catalysts that have been studied in the past have problems with durability during long-term operation. Noble metal catalysts are usually produced by coating an active coating layer made of r-alumina on a heat-resistant support such as coplite, and then applying Pd, Pd, and Pd.
It supports a catalytic metal such as L. Although such catalysts have high activity, at high temperatures of 1100° C. or higher, the active coating layer deteriorates and the surface area of the precious metal decreases or scatters, resulting in problems with long-term durability. Catalysts other than noble metals do not have such problems, but their activity is low at low temperatures and it is difficult to use them as they are.

[Purpose of the invention]

An object of the present invention is to provide a catalytic combustion method that has long-term durability.

[Summary of the Invention] The present inventors have arrived at the present invention as a result of intensive research on catalysts and phenomena for catalytic combustion. That is, as a result of research on noble metal catalysts, the present inventors found that catalysts mainly composed of Pd have superior combustion efficiency at low temperatures;
It was revealed that the catalyst containing tl as the main component has excellent activity at a temperature of about 600 to 1100°C. Also, when these catalysts burn high-concentration fuel, the temperature of the catalyst becomes too high and deterioration accelerates, and the temperature of the catalyst reaches 1100℃.
I got that it's not good to go beyond that. As a result, it was considered that if the turbine inlet temperature exceeds 1100° C., it would be difficult to achieve stable combustion for a long period of time with a material in which precious metals are supported on the active coating layer. Therefore, as a result of studying catalysts that can achieve stable combustion at high temperatures of 1,100°C or higher, we found that
It has been found that catalysts based on base metals without an active coating layer, such as noble metal catalysts, are preferred. These catalysts include Ca-? Zirconia stabilized with Mg or Y, doped with Co, Ni, Cr, etc.
C.

or Ni or a catalyst consisting of Cr and alumina spinel, lanthanum chromite or Ni.

It has become clear that those doped with Co are preferable. Although these catalysts have no problem in stability at 1100 to 1600°C, they have the disadvantage that combustion efficiency does not become high when the fuel concentration or temperature is low.

Therefore, the present inventors have comprehensively studied these matters and have arrived at the present invention. Here, since a conceptual diagram of the present invention is shown in FIG. 2, the present invention will be explained using this diagram. The combustor has two main catalyst filling sections. In the first stage catalyst filling section, a catalyst mainly composed of Pd is used in the first half, and a catalyst mainly composed of Pi is used in the second half. The adiabatic flame temperature of the mixture of fuel and air supplied to this part is 8
Since the temperature is 00 to 1200℃, even if combustion occurs, the temperature will be 1200℃.
Since the temperature is below ℃, there is little deterioration of the noble metal catalyst.

In addition, since the fuel pipe passes through the first stage catalyst filling section, heat is exchanged with the fuel and the catalyst does not overheat, and at the same time, there is little temperature drop when the fuel is injected at the first stage catalyst outlet. There are benefits. At the outlet of the first stage catalyst, the combustion gas and fuel are mixed, resulting in a temperature and fuel concentration that enable the second stage catalyst filling to work effectively.
Good combustion occurs. Although the temperature is high in this part, since the catalyst is made of stabilized zirconia doped with the above-mentioned base metal, it is highly stable and can maintain high combustion efficiency for a long period of time.

The present invention will be explained in detail below using examples.

[Example 1] The apparatus used in the experiment is shown in Figures 3 and 4. In FIG. 3, a combustion tube 12 was filled with a noble metal nickel catalyst, and a heated fuel/air mixture 14 was supplied from upstream. The honeycomb catalyst used had a diameter of 25 mm and a length of 15 L:rn. In FIG. 4, the same device as in FIG. 3 is used, and the pipe 17 is connected to the catalyst filling part so that the fuel 16 can be supplied. The inner diameter of the pipe was 8. That is, while the case in FIG. 3 assumes the conventional catalytic combustion method, the case in FIG. 4 shows a method based on the concept of the present invention.

In Fig. 4, the first stage catalyst filling section is filled with a Pd-based catalyst whose active coating layer is alumina containing rare earth elements in the first half, and a Pd-based catalyst in the second half. Filled. The second stage catalyst filling section 16 was filled with 5 cn1 of a stabilized zirconia catalyst doped with Ni.

In the experiments shown in FIGS. 3 and 4, the temperature of the mixture 14 of fuel and air supplied to the catalyst was 450°C. Natural gas is used as fuel, and the temperature of combustion gas 15 is 1100-15
The fuel concentration in the air-fuel mixture 14 and the fuel 16 supplied to the fuel pipe 17 were adjusted so that the temperature was 00°C. At this time, in the case of FIG. 3, the adjustment of the fuel concentration only changes the fuel concentration in the air-fuel mixture 14, but in the case of FIG. The temperature of the combustion gas 15 was adjusted using the fuel 16 supplied from the fuel pipe 17 so that the flame temperature (calculated value) was 1100°C. Figure 5 shows the changes in combustion efficiency over time in these experiments. In Fig. 5, curves a, b, and c are the results of the experiment shown in the third column, and curves a, e, and f are the results of the experiment shown in the fourth column.
These are the results of the experiment shown in the figure. Also, a and d are combustion gas 1
If the fuel is set so that the temperature of No. 5 is 1100°C, then b.

If e is similarly set to 1300℃, c,
Similarly, f is set to 1500°C. Note that the air flow rate was 24017 m1n.

As shown in FIG. 5, it is clear that in the case of the conventional example shown in FIG. 3, the higher the temperature of combustion gas is obtained, the faster the deterioration occurs and the durability is less. It can be seen that in the case shown in Figure 4, there is little such deterioration and there is durability.

[Example 2] Example 10 Using the same equipment as in the experiment of the present invention, the first and second stage catalyst filling portions were filled with lanthanum chromite doped with Ni. Then, the adiabatic flame temperature of the mixture supplied to the first stage catalyst filling section is changed, and the fuel 16 supplied from the fuel pipe 17 is changed, and the adiabatic flame temperature of the mixture entering the second stage catalyst filling section is changed. The combustion efficiency was measured by changing the The measured values were compared 100 hours after the start of operation.

The results are shown in Figure 6. In Figure 6, the horizontal axis is the first
The vertical axis represents the adiabatic flame temperature of the air-fuel mixture supplied to the catalyst filling section in the second stage and the mixture of combustion gas and fuel 16 at the outlet of the catalyst filling section in the first stage, which enters the catalyst filling section in the second stage. is the adiabatic flame temperature. As shown in Figure 6, the horizontal axis is 800 to 1200℃,
The vertical axis indicates that good combustion efficiency was obtained in range A of 1200 to 1600°C, indicating that it is important to perform combustion within this range.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a conventional catalytic combustion type gas turbine combustor, FIG. 2(a) is a partial cross-section of a gas turbine using the concept of the present invention, and FIG. 2(b) is a cross-sectional view along X-Y. Fig. 3 is a flow diagram of a model experimental device assuming catalytic combustion that has been studied in the past, and Fig. 4 is a flow diagram of a model experimental device assuming catalytic combustion of the present invention. % (a), φ), (, C) are for the conventional one, (d), (C) are explanatory diagrams for the inventive one, and FIG. It is a diagram showing the range of good firing efficiency in the case of the invention. 1... Primary fuel nozzle, 2... Igniter, 3... Wall air, 4... Swirler-15... Secondary fuel nozzle, 6.
...Kuhin nozzle...7...Precious metal catalyst filling part (
1st stage catalyst filling part) 8... 2nd stage catalyst filling part, 9... Furnace material supply pipe, lO... Inner cylinder, 11...
・Outer cylinder. Agent Patent Attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Uji Kait (hz)

Claims (1)

[Claims] (1) In the catalytic combustion method, in which fuel is combusted using a cast turbine, a mixture of fuel and air is supplied to the catalyst filling section of the first stage, and the mixture is passed through one or more pipes. , the fuel is separately supplied from the inlet of the pipe, jetted out from the outlet end of the pipe, mixed with the combustion gas from the first-stage catalyst-filled section, and then passed through the second-stage catalyst-filled section for combustion. The catalyst in the first half is further composed of multiple types of catalysts, the first half is a catalyst mainly composed of Pd, and the second half is a catalyst containing Pd as a main component.
A gasta catalyst characterized by being a catalyst mainly containing t is stabilized zirconia doped with at least one of Go, Ni, and Cr, or Co and Ni. Using a catalyst such as Cr alumina spinel, lanthanum chromite, or lanthanum chromite doped with at least one of Ni and Co, the adiabatic flame temperature of the mixed gas of fuel and air to the catalyst filling section is 800 to 12
00℃, and at the same time the adiabatic flame temperature of the mixture supplied to the second stage catalyst filling section is 1200 to 1600℃.
A gas turbine combustion method characterized in that fuel is supplied from a fuel pipe passing through a first stage catalyst filling section such that