JPS6142161B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a solid fuel combustion device using solid fuel such as briquettes, and in particular to an improvement in its exhaust gas purification unit. An object of the present invention is to provide a solid fuel combustion device that is equipped with an exhaust gas purification section that efficiently purifies exhaust gas without disturbing the combustion balance. Low-cost fuels such as charcoal briquettes are extremely economical and abundant resources, and solid fuel combustion devices using charcoal briquettes are used for two purposes: ondol (for room heating) and cooking. has been done. However, these low-cost fuels emit extremely large amounts of harmful substances (carbon monoxide, sulfur dioxide, hydrocarbons, hydrogen sulfide, etc.) when burned. Table 1 shows the typical exhaust gas composition.

[Table] As shown in Table 1, the highly concentrated toxic substances generated by briquette combustion caused many poisoners and deaths. (All of the harmful gas components in Table 1 are far above the lethal dose.) The present invention eliminates these drawbacks and takes the following into consideration. To install an exhaust gas purifying agent in a catalyst tank without disturbing the combustion balance. In particular, when using solid fuel, combustion is natural combustion, so a delicate combustion balance is required, and in order to install an exhaust gas purifier on this,
Compositional considerations are a major priority issue. If this point is ignored and the combustion balance is disrupted, even if an exhaust gas purifier is installed, the concentration of harmful gases generated from the solid fuel combustion equipment will increase and the effect of installing the exhaust gas purifier will be reduced, resulting in the opposite effect. induce work. On the other hand, if we go one step further from the above point of view and improve the combustion balance of solid fuel combustion equipment by installing an exhaust gas purifying agent in the catalyst tank, unburned gas (carbon monoxide, carbon monoxide, The concentration of harmful gases (such as hydrocarbons) is reduced by the composition of the catalyst tank and exhaust gas purifier.
Harmful exhaust gas is purified using an exhaust gas purifying agent, resulting in more complete purification. It is necessary to supply oxygen (air) to effectively oxidize harmful substances in exhaust gas. The combustion exhaust gas atmosphere is a reducing atmosphere, and the exhaust gas purifying agent installed here is reduced, particularly in the case of an oxide catalyst, thereby deteriorating the purification performance. (Other precious metal catalysts also deteriorate if used for a long time.) Oxygen supply serves to alleviate this reducing atmosphere. When installing the exhaust gas purifier above the main body of the solid fuel combustion equipment, determine the installation position of the exhaust gas purifier so that you can fully understand the purification function of the exhaust gas purifier and maximize the purification effect of the exhaust gas purifier. There is a need. In particular, the purification performance of exhaust gas purifiers varies depending on the type and composition of the catalyst.
All of these are highly dependent on temperature. Furthermore, the purification mechanism differs depending on the type of harmful gas, and it is necessary to determine the optimal installation position of the exhaust gas purifier to maintain the optimum temperature. An embodiment of the present invention will be described below with reference to the drawings. In Fig. 1, 1 is a briquette stove used as an example of a solid fuel combustion device, 2 is a primary air intake for combustion provided at the bottom of the briquette stove, 3 is a briquette provided in the briquette stove 1, and 4 is a briquette stove. In this catalyst tank 4, an exhaust gas purifying agent consisting of a desulfurizing agent 5 is provided in the upper part of the catalyst 6 and a desulfurizing agent 5 in the lower part. A secondary combustion chamber 8 having a secondary air intake port 7 is provided in the lower part of the catalyst tank 4. In the above configuration, when the ignited charcoal briquettes 3 are inserted into the briquette stove 1, air is taken in from the primary air intake port 2 for combustion, the briquettes 3 are combusted, and the exhaust gas is guided to the secondary combustion chamber 8. In addition, this secondary combustion chamber 8
The unburned gas is combusted by taking in fresh air from the secondary air intake port 7. In this case, the height of the standing flame changes depending on the amount of air taken in from the secondary air intake port 7. If the amount of air is small, the standing flame will be red and long, and if sufficient air is supplied, the standing flame will be long. The flame is blue and short. The fact that the flame is blue and short means that it burns in a state close to complete combustion, which reduces unburned gases such as carbon monoxide and hydrocarbons. In addition, by shortening the length of the flame, the installation position of the exhaust gas purifier can be moved closer to the combustion part, that is, the briquette 3 side, and the temperature of the exhaust gas purifier can be raised to a high temperature, making it possible to eliminate harmful substances in the exhaust gas. further improves purification performance. It is clear that the performance of an exhaust gas purifying agent generally improves as the temperature increases. In particular, the purifying effect of the desulfurizing agent 5 is more effective at higher temperatures, and this point will be explained in detail later. The advantages of bringing the exhaust gas purifying agent close to the combustion section have been explained above, but on the other hand, if the exhaust gas purifying agent is brought unnecessarily close to the combustion section and the flame comes into direct contact with the exhaust gas purifying agent, the following disadvantages occur. The exhaust gas purifying agent is locally heated, resulting in extremely poor temperature distribution, and the mechanical strength of the exhaust gas purifying agent is required. The oxygen concentration inside the flame is extremely low, and when this flame comes into contact with the exhaust gas purifier, it reduces the exhaust gas purifier and deteriorates the performance of the exhaust gas purifier. Because the unburned raw gas passes through the exhaust gas purifier without being completely combusted by the flame, it is not sufficiently purified by the exhaust gas purifier and is emitted in a state similar to raw gas. On the contrary, it will increase. The effect of providing the secondary air intake port 7 has been explained above, but there is also an optimum value for the area of the secondary air intake port 7, and if it is too small, the above effect will not be fully exhibited; If too much is done, harmful exhaust gases will leak from the secondary air intake port 7, producing the opposite effect. The relationship between the secondary air intake port 7 and the height of the standing flame has been explained above, but depending on the height of the standing flame,
The height of the secondary combustion chamber 8 will also be determined. The height of the secondary combustion chamber 8 of the present invention is defined as the distance between the briquettes 3 and the exhaust gas purifying agent, and the height of the secondary combustion chamber 8 is within a certain range of the area of the secondary air intake port 7. There is a correlation within. The smaller the opening area of the secondary air intake port 7, the higher the height of the secondary combustion chamber 8. Conversely, the larger the opening area of the secondary air intake port 7, the higher the height of the secondary combustion chamber 8. need to be low. The relationship between the height of the standing flame and the height of the rising flame has been explained above using the aperture area of the secondary air intake port 7 and the height of the secondary combustion chamber, and the optimum values for each according to experiments are shown below. Opening area of secondary air intake port 7
………5~100cm ² Secondary combustion chamber height ………5~30cm If the opening area of the secondary air intake port 7 is smaller than ^5cm2 , the amount of air supplied from here is necessary for complete combustion. The amount of air is small, and furthermore, the supply of oxygen to the exhaust gas purifying agent is insufficient, making it impossible to promote the oxidation reaction. In addition, when the opening area is larger than 100 ^cm2 , the amount of air necessary for complete combustion is satisfied, but in addition to taking in the air necessary for combustion, a part of the combustion exhaust gas containing harmful substances is Next, the characteristics of the exhaust gas leaked from the air intake port 7 were worsened. Next, when the height of the secondary combustion chamber 8 is greater than 30 cm, the purifying effect of the exhaust gas purifying agent deteriorates. As mentioned above, the purification effect is highly dependent on temperature, but in this case, it becomes a factor to lower the temperature of the exhaust gas purifying agent, and it is also a cause to increase the size of the device itself, which is not preferable. On the other hand, if the height of the secondary combustion chamber 8 is less than 5 cm, the exhaust gas purifying agent will be too close to the charcoal briquettes 3 and the flame will come into contact with the exhaust gas purifying agent, which is not preferred for the reasons mentioned above. Next, the exhaust gas purifying agent will be explained. Exhaust gas purifiers can be roughly divided into catalysts 6 that oxidize carbon monoxide and hydrocarbons into harmless carbon dioxide and water, and catalysts that adsorb and solidify sulfur dioxide to purify sulfur dioxide, which is one of the harmful components in exhaust gas. There is a desulfurizing agent 5 that does this. Next, this catalyst 6 and desulfurization agent 5 will be explained. Catalyst 6 Catalytic functions include (a) oxidizing carbon monoxide to carbon dioxide, (b) oxidizing hydrocarbons to carbon dioxide and water, (c)
Most preferred are catalysts that oxidize sulfur dioxide to sulfur trioxide. Traditionally, catalysts that serve this purpose include:
Various catalysts have been studied and industrialized. Main catalysts include noble metal catalysts (platinum, palladium, rhodium, etc.), metal oxide catalysts (oxide catalysts of manganese, copper, nickel, cobalt, chromium, etc.), and mixed catalysts using the above noble metal catalysts and metal oxides. There are various other harmful exhaust gas components in a briquette stove that uses briquettes as fuel, such as SO ₂ , CO,
Contains various harmful gas substances such as H, C, NOx, etc.
Since the concentrations of these gases are very high, a relatively strong catalyst is required for catalyst poisoning (particularly poisoning by sulfur dioxide). Precious metal catalysts can be said to be the most preferable catalysts from these points of view, but even with noble metal catalysts that are considered to be the best, their purification properties are highly dependent on temperature, so it is important to consider the installation of the catalyst. It is necessary. Desulfurization agent 5 Conventionally, there are dry method and wet method as desulfurization agent.
The currently mainstream wet method cannot be used for combustion equipment that uses solid materials as fuel, and a dry method must be used. The function of the desulfurizing agent used in this desulfurizing agent is that the desulfurizing agent itself oxidizes sulfur dioxide into sulfur trioxide, and also adsorbs and fixes the sulfur dioxide. The main components of the desulfurizing agent are hydroxides or carbonates of alkali metals such as calcium, magnesium, sodium, and potassium, and alkaline earth metals. The desulfurization reaction of an example of a desulfurization agent manufactured using these raw materials is shown below. The desulfurization agent mainly composed of calcium carbonate is CaCO ₃ +SO ₃ →CaSO ₄ +CO ₂ ↑. As in the above reaction, in the case of a desulfurizing agent made of carbonate, the carbonate is adsorbed and fixed as a sulfate, and in order to complete such a reaction, the higher the temperature of the exhaust gas purifying agent, the better. In the case of the above reaction, the desulfurization reaction starts at 350°C. A description will be given below based on specific examples. Example 1 Effects of providing the secondary air intake port 7 and
The optimal range of the opening area is shown in FIG. 2, and the relationship between the opening area of the secondary air intake port 7 and the exhaust gas concentration (carbon monoxide) is shown in FIG. This Figure 2 examines the effect of the secondary air intake port 7, and the curves a, b, c, d, and e are for the catalyst tank configured under the following conditions (corresponding to catalyst tank 4 in Figure 1). This is the case when using

[Table] In this experiment, one charcoal briquette was first burned, and after 4 hours, another briquette was added to the top (injected at the time of the X-ray in Figure 2).The carbon monoxide in the exhaust gas was This figure shows the temporal change in the concentration of . At this time, the primary air intake ports (2 in FIG. 1) were fully opened, and other conditions were the same except for the above conditions. As can be seen from FIG. 2, except for a, b, b, c, and e deviate from the conditions of the present invention, and the exhaust gas purification characteristics are not good. That is, in cases b and e, the opening area of the secondary air intake port 7 is small, and sufficient air cannot be supplied for secondary combustion, and the height of the combustion flame increases and comes into contact with the exhaust gas purifying agent. Purification function decreased. Further, in case c, the opening area of the secondary air intake port 7 was large, causing leakage of exhaust gas, and the purification properties were lower than in case a. Figure 3 examines the dependence of secondary combustion on height [cm] (distance between briquette 3 and gas purifying agent), and curves a, b, c, and d represent catalyst tanks configured under the following conditions. (corresponding to catalyst tank 4 in Figure 1), one charcoal briquette is burned, and after 4 hours, one new briquette is introduced (injected at the time of line X' in Figure 3). This is a measurement of the temporal change in carbon monoxide concentration in exhaust gas.

[Table] As you can see from this figure 3, if you exclude a and c,
b, d, and e deviate from the conditions of the present invention, and the exhaust gas purification characteristics are not good. That is, in case b, the height (cm) of the secondary combustion chamber 8 was too low, so that the combustion flame came into contact with the exhaust gas purifying agent, and the purifying function deteriorated. Further, in case d, the height (cm) of the secondary combustion chamber 8 was too high, so the temperature of the exhaust gas purifying agent decreased and the purifying function deteriorated. Furthermore, e is the case where no exhaust gas purifying agent is installed. As described above, the opening area of the secondary air intake port 7 and the carbon monoxide exhaust gas characteristics, as well as the height of the secondary combustion chamber 8 and the carbon monoxide exhaust gas characteristics, are each expressed by the combustion characteristics of the briquettes 3. Figures 4 and 5 show charcoal briquettes 3 being burned at the optimum values, that is, the opening area of the secondary air intake port 7 is 5 to 100 cm ² and the height of the secondary combustion chamber 8 is 5 to 30 cm. Figure 4 shows the changes in the aperture area of the secondary air intake port 7 and the carbon monoxide exhaust gas characteristics, and Figure 5 shows the height of the secondary combustion chamber 8 and the carbon monoxide exhaust gas characteristics. It is illustrated for clarity. For the carbon monoxide concentration, the peak value generated after the second briquette 3 was added was plotted. (This is the peak value at the X and X' lines in FIGS. 2 and 3.) Other conditions are the same in FIG. 4 as in FIG. 2, and in FIG. 5 as in FIG. 3. From Figure 4 above, it is understood that if the opening area of the secondary air intake port 7 is less than 5 ^cm2 , the exhaust gas characteristics will be extremely poor, and if it is more than 100 ^cm2 , the exhaust gas characteristics will be deteriorated due to exhaust gas leakage. be done. Also, from Figure 5, the height of the secondary combustion chamber 8 is 5 cm.
It is understood that exhaust gas characteristics deteriorate in the following cases and in cases where the length is 30 cm or more. Example 2 In Example 1 above, the opening area of the secondary air intake port 7 and the height of the secondary combustion chamber 8 were explained using the exhaust gas characteristics during combustion of the charcoal briquettes 3, but the secondary air intake port 7 The correlation between the aperture area and the height of the secondary combustion chamber 8 is shown in Table 2. The exhaust gas concentration (carbon monoxide concentration) was the same as that shown in FIGS. 4 and 5 of Example 1, and the peak value after the second briquette was added was shown. Other conditions are the same as in Example 1.

[Table] Table 2 above shows the exhaust gas characteristics when the aperture area of the secondary air intake port 7 and the height of the secondary combustion chamber 8 are mutually changed. There are also optimum values for the aperture area of the secondary air intake 7 and the height of the secondary combustion chamber 8, and when the secondary air intake 7 becomes small, the height of the secondary combustion chamber 8 increases. It's reasonably good. (6, 7, 8 in Table 2
(comparison) Conversely, when the secondary air intake port 7 is large, the smaller the height of the secondary combustion chamber 8 is, the better. (Comparison of 12, 13, and 14 in Table 2) Of course, if the opening area of the secondary air intake port 7 and the height of the secondary combustion chamber 8 deviate from the scope of the present invention, the exhaust gas characteristics will change. It also gets worse. The exhaust gas characteristics of carbon monoxide have been explained above, but the H・C and SO ₂ characteristics are also exactly the same, and even if only the area of the secondary air intake port 7 is regulated, the briquette 3
The exhaust gas characteristics due to the combustion ^of
It is necessary to install exhaust gas purifying agents in accordance with regulations on both sides of ^cm3 . As described above, according to the present invention, when the exhaust gas purifying agent is installed, the exhaust gas purifying agent can be effectively utilized to produce clean exhaust gas without deteriorating the exhaust gas characteristics. In addition, since the exhaust gas purifying agent has its desulfurization agent located upstream of the exhaust gas emitted from the solid fuel than the catalyst, the toxic substances emitted from the solid fuel during combustion are removed before the exhaust gas flows into the catalyst. The catalyst can be prevented from being disturbed by toxic substances, and its function can be stably exhibited over a long period of time. Furthermore, the desulfurization agent located upstream of the exhaust gas can easily ensure a space where the standing flame generated from the solid fuel does not come into contact with the catalyst, so contact with the standing flame will not cause a decline in catalyst function. There is no. Furthermore, since the desulfurization agent and catalyst are placed above the solid fuel, the combustion gas is applied to the bottom plate installed directly above the solid fuel to change its direction, and then the combustion gas is catalyzed. It can be made into a simple structure that does not require a complicated structure such as passing through a wire mesh.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a charcoal briquetting stove according to an embodiment of the present invention, and FIGS. 2 to 5 are exhaust gas characteristic diagrams of the same stove. 1...briquette stove, 2...combustion air intake,
3... Briquette (solid fuel), 4... Catalyst tank, 5...
...Desulfurizing agent, 6...Catalyst, 7...Secondary air intake port.

Claims (1)

[Claims] 1. A main body having a primary air intake and containing solid fuel, a catalyst tank provided above the main body, and an exhaust gas purifying agent provided in the catalyst tank. A secondary air intake is provided in the secondary combustion chamber formed between the exhaust gas purifying agent and the solid fuel in the main body, and the opening area of this secondary air intake is set to 5 to 100 ^cm2 . , the height of the secondary combustion chamber is set to 5 to 30 cm, the exhaust gas purifying agent is composed of a desulfurizing agent and a catalyst, and the desulfurizing agent is located upstream of the exhaust gas emitted from the solid fuel than the catalyst, A solid fuel combustion apparatus characterized in that a deflow agent and a catalyst are installed above the solid fuel so as to face each other.