JPS62138605A - Catalyst burning method and its device - Google Patents

Abstract

PURPOSE:To reduce the generation of NOx, to prevent the deterioration of catalyst, and to carry out continuous use even if high temp. burning is carried out by making vapor phase burning in such a way that fuel-air mixture is supplied and brought in contact with catalyst of honeycomb structure and then the mixture is burnt in vapor phase at the down flow area of the mixture. CONSTITUTION:When fuel-air mixture is brought in contact with a catalyst body 3 of honeycomb structure in a catalytic burning chamber 13 to catalyst burning, a part of the mixture is burnt at rather low temp. of 400-900 deg.C and fuel is reformed and burnt gas and unburnt mixture flow out from a number of through holes of the body 3 and are burnt in vapor phase at a vapor phase burning chamber 14 located at their down stream area to generate burnt gas having high temp. of 1,200-1,300 deg.C. As fuel flowing out from a number of through holes in dispersion form is burnt in this vapor phase burning, there is no local high temp. zone in the center part of a flame and NOx is scarcely generated and also burning catalyst is not deteriorated by heat.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a catalytic combustion method and apparatus suitable for cases where combustion at a high temperature close to X300°C is required, such as in a gas turbine combustor. (Prior art) In order to increase the thermal efficiency of gas turbines used for power generation and other purposes, it is required to raise the temperature of combustion gas as high as possible within the range that the turbine blades can withstand. Then 1100~1300゛c
A certain amount of combustion gas is supplied from the combustor. However, when such high '/14 combustion is performed using a normal burner, a high-temperature region is formed in the center of the flame, and in this high-temperature region, nitrogen in the air combines with oxygen, producing a large amount of N.
There is a problem that Ox is generated. Therefore, Japanese Patent Publication No. 58-164
As shown in Japanese Patent Publication No. 930 and Japanese Patent Application Laid-open No. 167621/1987, a catalytic combustion method is attracting attention in which the amount of NOx generated is reduced by bringing the air-fuel mixture into contact with a catalyst and catalytically combusting it on the surface of the catalyst. In these conventional methods, since it is necessary to raise the catalyst surface temperature to a level equal to or higher than the combustion gas temperature, the catalyst deteriorates rapidly and has a lifespan of only about 100 hours, making it almost impractical.

(Problems to be Solved by the Invention) The present invention solves the problems of the conventional catalytic combustion method as described above, and even when performing high-temperature combustion near 1300°C, N
This was completed with the aim of creating a catalytic combustion method and device that can extremely reduce the amount of Ox generated, prevent deterioration of the catalyst, and enable continuous use over a long period of time.

(Means for Solving the Problems) The present invention provides a controlled supply of a mixture of fuel and air, and causes catalytic combustion by bringing it into contact with a honeycomb structured catalyst body in which a combustion catalyst is supported on the surface of the honeycomb structured body. A first invention relating to a catalytic combustion method characterized in that vapor-phase combustion is then performed in a downstream region; and a mixer that mixes fuel and air, each of which has a flow rate controlled by a flow rate control device, at a predetermined ratio; It is characterized by comprising a catalytic combustion chamber equipped with a honeycomb structured catalyst body for catalytically combusting the air-fuel mixture obtained by the mixer, and a gas phase combustion chamber formed downstream of the catalytic combustion chamber. This invention also consists of a second invention relating to a catalytic combustion device.

The mixture used in the present invention is LNG or LNG.
The flow rates of hydrocarbon fuel such as PG and preheated air are controlled by flow rate controllers (10) and (11), respectively, and then a mixer (
12) is preferably mixed at a predetermined ratio. Such a mixture is formed in a honeycomb structured catalyst body (3
) into a catalytic combustion chamber (13). As the honeycomb structured catalyst body (3), a honeycomb structured body made of a heat-resistant ceramic material such as mullite or alumina, with a combustion catalyst supported on the surface thereof, is used. At least one of platinum, palladium, and rhodium is used as the combustion catalyst, and these combustion catalysts can be attached after supporting rAlz03, Zr0z, etc. on the surface of the honeycomb structure as described above. preferable. Among these combustion catalysts, palladium is also the most excellent in its ability to maintain gas phase combustion in the gas phase combustion chamber (14) formed downstream of the catalytic combustion chamber (13). In the present invention, a part of the air-fuel mixture is catalytically combusted when it passes through the honeycomb structure catalyst body (3), and the remaining part is catalytically burned in the gas phase combustion chamber (
Since gas phase combustion is performed in step 14), it is necessary to appropriately match the equivalent diameter of the through holes of the honeycomb structured catalyst body (3) and the space velocity of the air-fuel mixture passing through them. Here, the equivalent diameter is defined as 4 x (cross-sectional area of the through hole)/(inner circumferential length of the through hole), and as shown in the later examples, it is preferably 2°5fi or more, more preferably 2°5fi or more. It is better to set it to .511 or more and 10 cranes or less. In addition, the space velocity is defined as (mixture volumetric flow rate at 0°C and 1 atm)/(volume of honeycomb structured catalyst body), and is 500
00 (1/H) or more, and more preferably 5oooo to 600000 (1/If). If the equivalent diameter and space velocity are smaller than the above values, most of the combustion of the air-fuel mixture will be completed inside the honeycomb structure catalyst body (3), and the catalyst will become high temperature and the downstream gas phase combustion chamber (14) will be completed. ), the object of the present invention cannot be achieved. It should be noted that the honeycomb structured catalyst body (3) can also be used in combination with a plurality of types having different equivalent diameters of through holes.

(Function) The mixture of fuel and air whose flow rate is controlled by the flow rate control devices (10) and (11) and mixed at a predetermined ratio by the mixer (12) is first fed into the catalytic combustion chamber (13). ) When the mixture is brought into contact with the honeycomb structure catalyst (3) for catalytic combustion, a portion of the air-fuel mixture becomes 400 to 9
The fuel is reformed as it burns at a relatively low temperature of around 00°C, and a mixture of combustion gas and unburnt mixture flows out from the numerous through holes of the honeycomb structured catalyst body (3). Gas phase combustion occurs in the downstream gas phase combustion chamber (14),
A high temperature combustion gas of 1200-1300°C is obtained. In this gas phase combustion, the fuel flows out and burns in a dispersed manner through a large number of through holes, so there is no localized high-temperature area formed in the center of the flame, and there is no shadow of the combustion catalyst. Almost no NOx is generated. Also, catalytic combustion is 40
Since the combustion is carried out at a relatively low temperature of 0 to 900 °C, the combustion catalyst does not deteriorate due to heat, and as shown in the examples below, it is possible to maintain stable performance over a long period of time.

(Example) Next, examples of the present invention will be shown.

As shown in Figure 1, inside the pipe (1) there is a refractory (2
) was inserted to create a combustion tube with an inner diameter of 55 mm and a total length of about 90 ON, and inside it was a honeycomb structure catalyst body (3) with a diameter of 50 mm and a thickness of 25 mm, which supported palladium at a ratio of 10 g/1. A catalytic combustion chamber (13) and a gas phase combustion chamber (14) continuing on the downstream side thereof were formed in five stages. These honeycomb structured catalyst bodies (3) are produced by supporting r-Al□03 at a ratio of 100 g/l on a mullite honeycomb structure, calcining it at 600°C, impregnating it with a palladium chloride solution, and heating it in air at 450°C. After firing in the atmosphere, further heat to 450°C
It was made by firing in a hydrogen atmosphere. These honeycomb structured catalyst bodies (3) have an equivalent diameter force of 1.4 through holes.
am, 2,011.2.5111.4.81 poverty, 6.8
- Seal, 10.0 ■, and 13.01 So were prepared from 7 types of heather, and 5 of the same type were used. From the inlet f4 of this combustion cylinder to the flow rate control device (10), (11
) sends natural gas fuel and air preheated to 350°C to the mixer (12) and supplies natural gas to the combustion tube (4) so that the methane concentration is 4.8% by volume. and the space velocity is 30,000, 50,000, 100,000, 150,000, 600,000, 8
It was set to 00,000 (1/II). In this way, while performing catalytic combustion in the catalytic combustion chamber (13) and gas-phase combustion in the gas-phase combustion chamber (14), the temperature of each stage of the honeycomb structured catalyst body (3), the gas-phase combustion gas temperature, the outlet (
6), unburned methane concentration, NOx 4 degrees, etc. were measured.

The measurement data after continuing combustion for 2000 hours is as shown in the following table, and in the case marked with ○, catalytic combustion and gas phase combustion were performed at an equivalent diameter of 2.51 or more and a space velocity of 50,000 or more. The unburned methane concentration remains O even after 2000 hours.
~9ppm, NOx'/74 degrees is 4-6ppm
It can be seen that combustion gas having a temperature of 1310 to 1320°C can be obtained. On the other hand, in the case of the X mark, most of the fuel is catalytically combusted and almost no gas phase combustion occurs in the downstream region, and the catalyst reaches a high temperature of about 1300℃ immediately after the start of combustion, deteriorating and becoming a combustion catalyst. function is lost,
After 2000 hours, combustion could hardly take place, and the air-fuel mixture flowed out to the outlet (6) almost unchanged. Figure 2 shows each stage of the honeycomb structure catalyst (3) during combustion. It shows the temperature of the gas phase and the temperature of the gas phase combustion gas, where the equivalent diameter is 3.3 mm and the space velocity is 120,000
1/)l), △ is the data when the equivalent diameter is 5.0 yen and the space velocity is 120,000 yen (1/old).In these cases, the temperature inside the catalyst layer is 1000°C or more. The temperature reached 1300°C in the gas phase combustion region.

On the other hand, O has an equivalent diameter of 1.4 mm and a space velocity of 30,000 (
When 1/ I+ >, ・ is equivalent diameter 2.0f
The data is immediately after the start of combustion when the space velocity is 50,000 (1/H), and the temperature inside the catalyst layer is 1200 to 13
00°C, indicating that combustion is not occurring in the gas phase combustion region and the temperature is decreasing. As mentioned above, the catalyst deteriorates more rapidly in the case of O and .

(Effects of the Invention) As is clear from the above description, the present invention is capable of stably obtaining high-temperature combustion gas with extremely low NOx generation over a long period of time. As a catalytic combustion method and device suitable for gas turbine combustors, etc., which require a stable supply of gas, they will greatly contribute to the development of industry.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a graph showing temperature distribution at each stage of the apparatus shown in FIG. (3): Honeycomb structure catalyst body, (10), (11): Flow rate control device, (12): Mixer, (13): Catalytic combustion chamber, (14): Gas phase combustion chamber. 1st m

Claims (1)

[Claims] 1. A mixture of fuel and air is supplied in a controlled manner, brought into contact with a honeycomb structured catalyst body in which a combustion catalyst is supported on the surface of the honeycomb structured body, and then catalytically burned. A catalytic combustion method characterized by gas phase combustion in a basin. 2. A claim that uses a honeycomb structure catalyst body equipped with a large number of through holes with an equivalent diameter of 2.5 mm or more as a honeycomb structure catalyst, and burns the air-fuel mixture while supplying it at a space velocity of 50,000 (1/H) or more. The catalytic combustion method according to item 1. 3. The catalytic combustion method according to claim 1, which uses a honeycomb structured catalyst body in which a combustion catalyst containing palladium is supported on the surface of the honeycomb structured body. 4. A mixer (12) that mixes fuel and air whose flow rates are controlled by the flow rate control devices (10) and (11) at a predetermined ratio, and a mixture obtained by the mixer (12) that is catalyzed. It is characterized by consisting of a catalytic combustion chamber (13) equipped with a honeycomb structured catalyst body (3) to be combusted, and a gas phase combustion chamber (14) formed downstream of the catalytic combustion chamber (13). Catalytic combustion equipment.