JPH0132404B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lean gas fuel combustion device that stably burns lean gas fuel, and is particularly advantageous when the concentration (equivalence ratio) of the lean gas fuel changes. .

Generally, gaseous fuels have flammability limits. When the ratio of gaseous fuel to air or oxygen exceeds a certain specific value (flammability limit), it becomes impossible to combust or to continue stable combustion. This premixture (mixture in which air or oxygen is mixed with gaseous fuel in advance) below the flammability limit is called lean gaseous fuel, but as mentioned above, it has been difficult to burn this lean gaseous fuel in the past. However, in recent years, there have been research reports showing that even if the fuel is a diluted gas, if it is preheated to a certain temperature or higher, the flammability limit virtually disappears. For example, in the case of a premixture of methane and air, if it is preheated to around 1400K, complete combustion can be achieved even with a lean gaseous fuel.

Based on the above, if combustion for burning lean gaseous fuel can be put to practical use, it will be possible to recover energy from the lean gaseous fuel that is above the flammability limit, which was previously discarded into the atmosphere, and this will greatly contribute to energy conservation. . Furthermore, it is attracting a lot of attention because it eliminates the cause of air pollution caused by releasing dilute gaseous fuel into the atmosphere.

Thus, from the viewpoint of energy saving and environmental protection, it is desired to develop a technology for stably burning diluted gas fuel. Various devices have been proposed to burn lean gaseous fuel, but all of them have complex structures that make them difficult to use, and the devices themselves are expensive. In order to preheat the heat to a high temperature, it is necessary to apply additional energy from the outside, which is often economically disadvantageous, and therefore, there have been no examples of sufficient success in putting it into practical use.

The present invention is a lean gas fuel combustor that can stably burn a lean gas fuel with a device with a simple structure, and can preheat the lean gas fuel to a high temperature without applying additional energy from the outside during steady combustion. The purpose is to provide equipment.

The lean gas fuel combustion device of the present invention includes a combustion vessel including a primary passage and a secondary passage formed in the primary passage across a combustor wall, and a plurality of pore groups provided in each passage of the combustion vessel. and a plurality of combustion chambers provided on the downstream side of the group of pores, one end of each passage is in communication with each other, and the other end of the primary passage is in communication with the intake port for the lean gas fuel. The other end of the next passage is configured to communicate with the combustion gas outlet.

The premixed gas supplied into the primary passage is preheated by the group of fine holes, enters the combustion chamber provided downstream thereof, and is mixed. This preheating and mixing process is repeated each time it passes through multiple pore groups provided in the primary and secondary passages and the combustion chamber, and the temperature of the premixture is gradually raised until it reaches a high temperature until it reaches the combustion chamber at the most downstream position. Complete combustion occurs, heat exchange is performed efficiently, and the combustion of lean gaseous fuel can be continued stably.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the lean gas fuel combustion apparatus of the present invention will be described with reference to FIGS. 1 and 2.

In the figure, reference numeral 1 denotes a combustion vessel of a combustion device, and a secondary passage 2 that penetrates is formed in the center of this combustion vessel 1, and a penetrating passage 2 is formed around the secondary passage 2 with a combustor wall 3 in between. A primary passage 4 is formed. As shown in FIG. 2, a plurality of primary passages 4 are provided so as to surround the secondary passage 2. Each primary passage 4 is provided with three pore groups 5, and a combustion chamber 6 is provided between the pore groups 5. Similarly, three pore groups 7 are provided in the secondary passage 2, and a combustion chamber 8 is located between the pore groups 7.
is provided. In this example, pore groups 5 and 7
Each is composed of a large number of tubules. A flange 9 is attached to one end of the combustion vessel 1 so that one end of the primary passage 4 and one end of the secondary passage 2 communicate with each other. Air-fuel mixture intake 10a
The other end of the secondary passage 2 is connected to a combustion gas outlet 11 formed by a flange 11.
It is connected to a. In FIG. 2, 12 is a heater for heating the pore groups 5, 7 and the combustion chambers 6, 8 to a high temperature when starting up this combustion device, and as shown in the figure, a heater 12 is used to heat the pore groups 5, 7 and the combustion chambers 6, 8 to a high temperature. Several pieces are buried in the combustor wall 3 between them.

Next, the operation of the apparatus of the present invention described above will be explained. Here, an example will be explained in which a lean gaseous fuel of methane and air is burned. When starting up the combustion device, first, by energizing the heater 12, the pore groups 5, 7 and the combustion chambers 6, 8 are heated to around 1400K or at least 900K, which is the reaction starting temperature.
Heat to above temperature. After that, in a normal combustion device, a premixture of methane and air (lean gaseous fuel) below the flammability limit is introduced into the primary passage 4 from the inlet 10a.
supply within. The premixed gas supplied into the primary passage 4 is first preheated by the most upstream pore group 5, and then flows into the combustion chamber 6 provided downstream of the pore group 5, where it is further mixed. into pore group 5. In this way, the premixed gas flows through the primary passage 4 while being repeatedly preheated and mixed, and when it reaches one end of the primary passage 4, it enters the secondary passage 2 through the passage 9a formed by the flange 9. Secondary passage 2
The premixed gas that has entered is repeatedly preheated and mixed by the alternatingly provided pore groups 7 and combustion chambers 8 in the same way as when it passed through the primary passage 4, and then flows downstream.
In this manner, in the apparatus of the present invention, the premixed air is repeatedly preheated and mixed by the alternatingly provided pore groups 5 and 7 and the combustion chambers 6 and 8, and then flows downstream. The pore groups 5 and 7 and the combustion chambers 6 and 8 are heated to a sufficiently high temperature, and the heat transfer area of the pore groups 5 and 7 is extremely large compared to the passage area, so the premixture flows through the pore groups 5 and 7. The mixture is preheated very efficiently in 7 and flows downstream, and when it is preheated to about 900K in certain pore groups 5 and 7, a combustion reaction gradually starts, and the premixture that has started the combustion reaction is provided downstream. Complete combustion occurs while passing through the combustion chambers 6 and 8 and the pore groups 5 and 7, and the temperature of the combustion gas rises to about 1300 to 1500K. This combustion gas then heats the combustor wall 3 while passing through the primary passage 4 or the secondary passage 2. Particularly, when the combustion gas passes through the pore groups 5 and 7 provided on the downstream side, heat exchange is performed efficiently and the combustor wall 3 is heated to a high temperature, thereby reducing the pore groups 5 and 7 and the combustion chamber. 6 and 8 are heated to around 1400 K after the start of combustion, and even if the power to the heater 12 is stopped, the combustion can be continued stably. In this way, during steady combustion in the combustion device, it is possible to preheat the lean gaseous fuel to a high temperature and combust it without applying any other energy from the outside. In the device of the present invention, the position where the lean gaseous fuel (premixture) is combusted changes depending on the concentration (equivalence ratio) of the gaseous fuel (premixture). That is, in the case of rich fuel, the reaction initiation temperature is low, so it is combusted in the combustion chamber 6 on the upstream side of the primary passage 4, and in the case of thin fuel, the reaction initiation temperature is high, so combustion is carried out on the downstream side of the secondary passage 2. room 8
burns with Further, if the passage 9a formed by the flange 9 and the outlet 11a formed by the flange 11 are maintained at a high temperature to the same level as the combustion chambers 6 and 8, the passage 9a and the outlet 11a are It may also burn. Therefore, in the apparatus of the present invention, a wide range of lean gaseous fuels, from rich to thin, can be combusted in the combustion chambers 6 and 8, which are located at optimal combustion positions, and in particular, in the combustion chambers 6 and 8, which are located at the optimum combustion positions. Since there are multiple heat exchange areas and a large heat exchange area, it is possible to burn even thinner fuels. In addition, since the combustion gas efficiently exchanges heat with the combustor wall 3 when passing through the pore groups 5 and 7, even if combustion occurs in the combustion chamber 8 in the secondary passage 2, all the pore groups 5 , 7 and the combustion chambers 6, 8 can be maintained at high temperatures. The device of the present invention is particularly effective when the concentration (equivalence ratio) of dilute gaseous fuel changes frequently. That is,
In the case of rich fuel, the combustion temperature is high and it is combusted on the upstream side of the primary passage 4, so that the combustion gas is sufficiently exchanged with the combustor wall 3, and the combustion gas is removed from the outlet 11a.
The temperature of the combustion gas taken out from the combustor wall 3 decreases considerably, and if the fuel is thin, the combustion temperature decreases, but since it is combusted downstream of the secondary passage 2, the amount of heat exchange with the combustor wall 3 is small, making it difficult to remove the fuel. The temperature of the combustion gas taken out from the outlet 11a does not decrease much. Therefore,
Even if the temperature of the fuel changes, it is possible to obtain combustion gas that is at a nearly constant temperature at all times, and the temperature of this combustion gas is
Since it is about 1300 to 1400K, it is convenient for use in gas turbines and the like.
Furthermore, since fuel of any concentration can be combusted, combustion gas can be obtained at an optimal temperature depending on the application.

Although not specifically mentioned in the above embodiment, the combustor wall 3 forming the combustion chambers 6 and 8
The material of the thin tubes constituting the pore groups 5 and 7 must be selected from materials that can withstand a high temperature corrosive atmosphere, such as heat-resistant steel or ceramic. In addition, in this embodiment, the pore groups 5 and 7 are composed of a large number of thin tubes, but the pore groups 5 and 7 are not limited to this. Any material is fine. Furthermore, in this embodiment, the secondary passage 2 is formed in the center of the combustion vessel 1, and the primary passage 4 is formed around this secondary passage 2, but the reverse is true, that is, the secondary passage 2 is formed in the center of the combustion vessel 1. A primary passage may be formed in the primary passage, and a secondary passage may be formed around the primary passage, and this is also included in the present invention as another embodiment. However, the embodiment shown in FIG. 1 in which the high-temperature combustion gas is configured to pass through the center of the combustion vessel 1 is more effective in reducing heat leakage. Further, a plurality of passages 4 are provided around a passage 2 provided in the center of the container 1, but the passages 2 and 4 may be formed by configuring the container 1 in a double cylindrical shape, or The passages 4 may be arranged side by side on one side of the passage 2, and in this case, there may be only one passage 4. It is not necessarily necessary to provide a plurality of pore groups 5, 7 and combustion chambers 6, 8 provided in the primary passage 4 and secondary passage 2, respectively.
One pore group and one combustion chamber may be provided in each.

As described in detail above, the lean gas fuel combustion device of the present invention includes a secondary passage provided in the primary passage across the combustor wall, a group of pores provided in each passage, and a group of pores provided on the downstream side of the group of pores. Since it is configured with a combustion chamber, it is possible to stably burn a wide range of lean gaseous fuels, from rich to thin, and during steady combustion, it is possible to burn lean gaseous fuel without applying any external energy. can be preheated to a high temperature and combusted. Furthermore, the device of the present invention has a simple structure and is highly practical. Therefore, it becomes possible to recover energy from diluted gaseous fuel, which greatly contributes to energy saving and also eliminates the cause of air pollution, thereby contributing to environmental conservation. Furthermore, since the combustion of lean gaseous fuel results in low-temperature combustion, it has the effect of significantly reducing _NOx , a pollutant component, generated in the combustion gas.

[Brief explanation of drawings]

FIG. 1 is a simplified vertical sectional view showing an embodiment of the lean gas fuel combustion apparatus of the present invention, and FIG. 2 is a -
It is a line arrow view. 1... Combustion vessel, 2... Secondary passage, 3... Combustor wall, 4... Primary passage, 5, 7... Pore group, 6,
8... Combustion chamber, 10a... Intake port, 11a... Outlet port.

Claims (1)

[Scope of Claims] 1. A combustion vessel comprising a primary passage and a secondary passage formed in the primary passage with a combustor wall in between, a plurality of pore groups provided in each passage of the combustion vessel, and It has a plurality of combustion chambers provided downstream of the group of pores, and one end of each passage communicates with each other, the other end of the primary passage communicates with the lean gas fuel intake, and the secondary passage communicates with the other end of the primary passage. A lean gas fuel combustion device characterized in that the other end is configured to communicate with a combustion gas outlet. 2. The lean system according to claim 1, characterized in that a secondary passage is formed in the center of the combustion vessel, and a primary passage is formed around the secondary passage with a combustor wall in between. Gaseous fuel combustion equipment. 3. The lean gas fuel combustion apparatus according to claim 2, wherein a plurality of primary passages are formed to surround the secondary passage. 4. The lean gas fuel combustion device according to any one of claims 1 to 3, wherein the pore group is constituted by a large number of thin tubes.