JPH0894066A - Heat storage - Google Patents

Abstract

(57) [Summary] [Purpose] NO even if high temperature gas is introduced into the heat storage body at high temperature.
It enables purification of harmful exhaust gas components such as x, CO, and HC. In addition, reliability in heat storage combustion under high temperature and corrosive environment is improved. A heat storage body (3) for giving sensible heat of the high temperature gas to the low temperature gas by alternately passing the high temperature gas and the low temperature gas from opposite directions in a short time is divided into at least a plurality of fluid flow directions, and more preferably Are formed of different materials or different structures depending on the high temperature gas inlet side and the low temperature gas inlet side. More preferably, the exhaust purification catalyst is carried in the catalytic reaction temperature region of the heat storage pair. . Further, these heat storage bodies 3 are of a heat storage combustion type burner that burns using high temperature combustion air obtained by alternately passing the fuel exhaust gas and the combustion air through the flow passage switching means to the heat storage body. A part of the heat storage body divided into air throats is installed inside, and the rest is installed outside the burner in the vicinity of the flow path switching means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage body. Furthermore,
More specifically, the present invention relates to an improvement of a heat storage body that gives sensible heat of the high temperature gas to the low temperature gas by alternately passing the high temperature gas and the low temperature gas from opposite directions.

[0002]

2. Description of the Related Art In recent years, heat storage combustion has been considered in which a heat storage medium is used to preheat combustion air to a high temperature close to the temperature of exhaust gas for highly efficient exhaust heat recovery. As a heat storage material used for this heat storage combustion, for example, a honeycomb-shaped ceramic in which a large number of cell holes are formed by thin partition walls as shown in the figure has been conventionally attracted attention as a suitable one. Here, the honeycomb shape is not limited to a case where a large number of original regular hexagonal cell holes are provided, and includes a case where the cells are formed by regular square cell holes as shown in the drawing.

[0003]

However, when the hot gas and the low temperature gas are alternately flown from the opposite directions, the hot gas is introduced before the heat storage body is heated almost uniformly throughout the flow switching. A considerable temperature difference between the mouth side and the low-temperature gas inlet side, for example, after 20 to 30 seconds from the flow switching, 1000 ° C on the furnace side, 200 ° C on the valve side, and 800 ° C.
Temperature difference occurs. Since the material of the heat storage body having such a large temperature difference is limited to those having high temperature heat resistance and thermal shock resistance, it becomes expensive. Moreover,
In the case of a ceramic honeycomb heat storage body, it must be a material that can be manufactured in various shapes. Also, depending on the application,
For example, when applied to a burner system of equipment that uses flux such as an aluminum melting furnace, the material must also have corrosion resistance, and soot, aluminum fume, and flux for melting should be used during exhaust. Due to the inclusion of dusts such as, the honeycomb ceramics with small cell holes may be clogged with long-term use.

Further, in general, when heat storage combustion is performed, the combustion preheat air temperature becomes high and NOx increases. Also, since the reaction activity is high and sufficient combustion is possible even with a low air ratio,
Although it is possible to burn in a reducing atmosphere, a large amount of HC and CO are generated during reducing combustion. Conventionally, the burner structure itself has been improved in order to reduce these harmful exhaust gas components, but since it is difficult to satisfy both of these problems and combustion stability, purification of exhaust gas by a catalyst may be considered. Purification of exhaust gas with a catalyst causes sintering if the exhaust temperature is higher than the catalyst reaction temperature, and if the temperature is too low, the reaction will be insufficient or will not occur at all.
Generally, it is controlled in advance to an appropriate reaction temperature range of the catalyst by injecting dilution air or releasing heat from a heat storage body. For example, in the case of a platinum catalyst mainly used for purifying only CO or HC, the range is 700 ° C to 150 ° C, and in the case of a platinum rhodium catalyst used for simultaneously purifying CO and NOx, it is about 500 ° C to 300 ° C. Adjusted to the range of ℃. Therefore, when the catalyst is to be supported on the heat storage body of the heat storage combustion, the temperature of the gas on the high temperature side to be introduced must be lowered by injecting diluted air to such an extent that a catalytic reaction occurs. There is a problem of decline.

Therefore, it is an object of the present invention to provide a heat storage body capable of purifying harmful exhaust gas components such as NOx, CO and HC even when high temperature gas is introduced into the heat storage body at a high temperature. In addition, an object of the present invention is to provide a heat storage material that improves reliability in high temperature / corrosive environments in heat storage combustion.

[0006]

To achieve the above object, the present invention provides the sensible heat of the hot gas to the cold gas by alternately passing the hot gas and the cold gas from opposite directions in a short time. The heat storage body is divided into a plurality of parts at least in the fluid flow direction.

Further, the divided heat storage body of the present invention is made of different materials for the one close to the high temperature gas introduction port side and the one close to the low temperature gas introduction port side.

Further, the divided heat storage body of the present invention is formed with a different structure for the one close to the high temperature gas introduction port side and the one close to the low temperature gas introduction port side.

Further, the divided heat storage body of the present invention carries an exhaust purification catalyst in the catalytic reaction temperature region.

Further, the heat storage body according to any one of claims 1 to 4 of the present invention is a high temperature obtained by alternately passing the fuel exhaust gas and the combustion air to the heat storage body via the flow path switching means. A part of the heat storage body divided into the air throat of the heat storage combustion type burner that burns using the combustion air is installed, and the rest is installed outside the burner in the vicinity of the flow path switching means. .

[0011]

Therefore, in the case of the heat storage body according to the first aspect of the present invention, the high temperature gas of the heat storage body is formed by performing the heat storage combustion in which the high temperature combustion exhaust gas and the low temperature combustion air are alternately flowed in order to improve the thermal efficiency. Even if a large temperature difference is generated between the portion closer to the inlet side and the opposite portion closer to the low temperature gas inlet side, the difference in thermal expansion between the divided heat storage bodies is reduced and cracking can be prevented.

Further, the corrosion of the heat storage body progresses remarkably at a high temperature portion near the high temperature gas introduction port side and is slow at a low temperature portion near the low temperature gas introduction port side. Therefore, in the case of the heat storage body according to claim 2, a heat storage body having heat resistance and acid resistance is used only for the heat storage body near the high temperature gas inlet side, and the life and cost are reduced without impairing the function as the heat storage body. Can be converted.

Further, according to the heat storage body of claim 3, when the high temperature combustion exhaust gas containing dust and the like is introduced, the heat storage body on the side of the high temperature gas introduction port which first comes in contact with the exhaust gas has a filter function. Can be adopted, and clogging of the heat storage body can be prevented.

Further, in the case of the heat storage body according to claim 4, the high temperature gas and the low temperature gas are alternately passed from opposite directions in a short time so that the high temperature gas introduction side and the low temperature gas introduction side of the heat storage body are formed. Since the catalytic reaction temperature range is set within the temperature difference between the two, the HC, CO, NOx contained in the high temperature gas
Etc. can be completely purified, and the reaction heat generated at that time is used for preheating when the low-temperature gas / combustion air is passed, and is effectively used.

Further, according to the heat storage body of claim 5, the burner and the equipment equipped with the burner can be downsized without changing the heat storage capacity and capacity.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to an embodiment shown in the drawings.

FIG. 4 shows an example of a heat storage combustion type burner system using the heat storage material of the present invention. This heat storage combustion type burner system obtains combustion air preheated to a high temperature close to the combustion exhaust gas temperature by using the heat storage body shown in FIGS. 1 to 3 when alternately burning a pair of burners 1 and 2. I am trying. That is, the air supply system and the exhaust system are alternately switched between the pair of burners 1 and 2, and the direct heat exchange in which the combustion exhaust gas and the combustion air are alternately flown to the heat storage body, a temperature close to that of the combustion exhaust gas, For example, the combustion air is preheated to a high temperature of 700 to 800 ° C. or higher.
This heat storage combustion type burner system is a combination of two heat storage bodies 3 which are connected to and integrated with the burner bodies 4 and 5, while one burner burns while the other burner and heat storage body do not burn. It is provided so as to discharge the combustion exhaust gas through. An air supply system 6 for supplying combustion air and an exhaust system 7 for exhausting combustion gas can be selectively connected to the two burners 1 and 2 by interposing a flow path switching means 8, and one burner is provided. 1 (or 2) is provided so as to supply combustion air through the heat storage body 3 while exhausting combustion gas from the other burner 2 (or 1) through the heat storage body 3. Combustion air is supplied by, for example, a pushing fan (not shown), and combustion exhaust gas is sucked from the furnace by exhaust means (not shown) such as an induction fan, and after being subjected to necessary processing such as dust collection. Emitted into the atmosphere. Further, the fuel supply system is selectively connected to the fuel nozzles 9 of either one of the burners 1, 2 through a three-way valve or the like to supply the fuel, though not shown.

Here, as the heat storage body 3, as shown in FIG. 3, honeycomb-shaped ceramics, such as cordierite or mullite, having a constant passage cross-sectional area and linear passages penetrating, or heat and acid resistance. Use of other excellent materials is preferable. This honeycomb-shaped ceramic has a large heat capacity and high durability, but relatively low pressure loss.
Moreover, exhaust and air supply are alternately performed without stagnation. Therefore, the dust in the exhaust gas is unlikely to adhere to the honeycomb-shaped flow path of the heat storage body, and even if the dust adheres, it is backwashed, and therefore is less likely to be contaminated. Furthermore, when heat is recovered from the exhaust gas, even if the exhaust gas falls below the acid dew point temperature, the sulfur content in the exhaust gas and its chemical change substances are captured on the surface of the ceramics, causing low-temperature corrosion of the exhaust system ducts, etc. located downstream. Never.

Furthermore, it is preferable that the heat storage body is divided into multiple layers and arranged at least in the flow direction of the fluid. This is because when the pair of burners 1 and 2 are alternately burned in a short time in order to improve the heat storage efficiency, the temperature of the heat storage body is, as shown in FIG. However, the temperature becomes higher at the opposite side of the low temperature gas inlet side, that is, the portion near the switching valve side. When such a heat storage body 3 is integrally formed, since the flow paths are frequently switched, the temperature difference becomes large, and thus the possibility of cracking due to the difference in thermal expansion increases. Therefore, by dividing the heat storage body 3 into multiple layers, the difference in thermal expansion between the blocks 3a, 3b, 3c, ..., 3e is reduced to prevent cracking due to the difference in thermal expansion. As an example, the heat storage body 3 is shown in FIG.
It is shown divided into a, 3b, and 3c. At this time, it is desirable to sandwich the cushioning material 12 between the heat storage bodies 3a, 3b, 3c. The heat storage body 3 is not only divided in the gas flow direction, but is also divided in the direction orthogonal to the flow direction as necessary.

Corrosion of the heat storage body 3 is caused by the hot gas inlet 1
The progress is remarkable at the high temperature portion near the 0 side, and is slow at the low temperature portion near the low temperature gas introduction port 11 side. Therefore, the heat storage body 3
Making the whole from an expensive corrosion-resistant material results in unnecessary costs. Therefore, the heat storage material made of a corrosion resistant material may be used only in the high temperature portion on the furnace side, and an inexpensive heat storage material may be used in the other portions. Further, as a method of extending the life of the heat storage body, it is also preferable to increase the wall thickness t of the honeycomb at the high temperature portion. In this case, a decrease in heat storage capacity is expected, but it can be avoided by using a material having high thermal conductivity. When a high temperature furnace with a furnace temperature of about 1500 ° C. is used, a high heat-resistant heat storage material is used for the first and second heat storage bodies 3a, 3b near the high temperature gas inlet 10 side, and the others are inexpensive. It is desirable to choose one.

Further, in an environment involving dust such as flux, the use of a honeycomb type heat storage body as shown in FIG. 3 may cause clogging. Therefore, as a countermeasure against this, as shown in FIG. 2, a highly heat-resistant ball-shaped or nugget-shaped heat storage body that is easy to manufacture and inexpensive as a filter is added to the first heat storage body 3a near the high temperature gas introduction port 10 side. Adopted so that it can be exchanged at all times, 2 layers, 3
A honeycomb type heat storage material may be used for the layer. Further, instead of the honeycomb heat storage body for the second layer and the third layer, a ball or nugget heat storage body having finer particles than the first layer may be adopted.

Further, in this embodiment, the heat storage body 3 is installed at the rear of the burner throat part, but it is installed on the furnace side in order to reduce the loss of sensible heat in the furnace as much as possible and to use the space of the thickness of the furnace wall. A heat storage body may be installed. In such a case, since there is generally no space in the burner installation space, it may not be possible to insert all the heat storage bodies of the required capacity. In such a case, although not shown, if the heat storage body 3 is divided, one is installed inside the air throat of the burner, and the other is installed near the flow path switching means, the loss of high temperature exhaust gas is small and the furnace compact It can be realized. Further, as described above, in the case of using a combination of heat storage bodies having multiple functions and various structures, it is not always necessary to store them in the same heat storage chamber. The heat storage chamber according to the function and structure is divided and installed, and the exhaust gas and air flow paths are connected in series by a heat insulation duct, so that the degree of freedom in design and construction can be secured.

Further, when a high temperature gas containing NOx, CO or HC is used, for example, in the case of heat storage combustion or reduction combustion using combustion air preheated to a high temperature, an exhaust gas purification catalyst is provided in a part of the heat storage body. It is preferable to support it before use. For example, if you want to purify CO with an oxidation-promoting catalyst,
100% CO up to about 5% in the range of about 150-700 ° C
% Can be purified. On the other hand, the temperature of the heat storage body is high (for example, 100) on the side of the high temperature gas inlet 10 by alternately passing the high temperature gas and the low temperature gas from opposite directions in a short time.
However, the temperature becomes low (for example, about 200 ° C.) on the low temperature gas inlet 11 side. Therefore, FIG. 5 (A)
As shown in FIG. 3, the heat storage body 3 is divided into multiple layers in the fluid flow direction, and the catalyst is supported on the block corresponding to the temperature distribution region suitable for the reaction of each catalyst, whereby 100% CO
Can be purified. Further, in the case of purifying CO, an exothermic reaction occurs in the heat storage body, but since the heat can be used for preheating the combustion air after switching, no thermal loss occurs. Furthermore, if CO and HC can be purified, combustion in a reducing atmosphere becomes possible, and oxidation of the object to be heated, molten aluminum, etc. can be prevented. Similarly, with respect to NOx, a catalyst may be supported in a required temperature range. For example, in the case of purifying only CO or HC, a platinum catalyst is mainly used. The reaction temperature range of this platinum catalyst is about 150 ° C. to 700 ° C., and if the temperature is higher than that, sintering occurs and the catalyst cannot be used, and if it is lower than that, catalytic reaction does not occur. Therefore, FIG. 5 (A)
In the case shown in (1), the platinum catalyst is loaded from the second layer heat storage block 3b near the high temperature gas introduction port 10 to the final layer heat storage block 3e near the low temperature gas introduction port 11. Further, when CO and NOx are simultaneously purified, platinum partially added with rhodium is used. The ratio of platinum to rhodium is platinum: rhodium = 5: 1 to 20:
About 1 is preferable, and the temperature range is preferably about 300 ° C to 500 ° C. Therefore, in the case shown in FIG. 5A, the heat storage block 3c of the third layer from the high-temperature gas inlet 10 or the heat storage blocks 3b before and after including the same,
Platinum rhodium is preferably supported on part or all of 3d. Therefore, while passing the combustion exhaust gas, the portion of the heat storage body heated to about 150 ° C. to 700 ° C., that is, the second-layer heat storage body block near the high temperature gas inlet 10 in FIG. 3b to the final layer heat storage block 3e near the low temperature gas inlet 11 and / or a portion heated to about 300 ° C to 500 ° C, that is, the third layer heat storage block 3c or By carrying a platinum rhodium catalyst on a part or all of the heat storage block 3b, 3d before and after containing CO
Alternatively, HC or NOx can be removed from the exhaust gas.

The above embodiment is an example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, a case has been mainly described in which high-temperature combustion air is obtained by alternating combustion using a heat storage body connected to or incorporated in a burner, but the present invention is not particularly limited to this, and for example, a combustion air supply system. And the exhaust system by rotating the heat storage body relative to the exhaust system, or by switching the flow direction of the fluid with respect to the heat storage body by using the flow path switching means, etc. The air preheated to a high temperature may be continuously supplied to a single burner for continuous combustion.

[0025]

As is apparent from the above description, in the case of the present invention, there is no risk of cracks or the like even if a large temperature difference occurs between the inside of the furnace and the side of the flow path switching means. It is possible to switch between, and the thermal efficiency is improved.

According to the second and third aspects of the present invention, a heat storage material or heat storage structure is appropriately divided into a portion requiring heat resistance and acid resistance and a portion not requiring heat resistance, or a fluid containing dust and a fluid not containing dust. Since it is possible to use the heat storage device, it is possible to reduce the cost of the heat storage body and to continuously use the equipment for a long period of time.

Further, in the case of the invention as claimed in claim 4, CO contained in the combustion exhaust gas by supporting the exhaust purification catalyst on the heat storage body.
Since it is possible to capture HC and HC, it is possible to reduce NOx even when prioritizing the stability of combustion, such as during reduction combustion, and without using a low NOx burner having a complicated structure.

Furthermore, in the case of the heat storage body according to the fifth aspect, it is possible to make the burner compact without changing the thermal efficiency, and thus make the entire equipment equipped with the burner compact.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a heat storage body of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the heat storage body of the present invention.

FIG. 3 is a perspective view showing an example of a honeycomb ceramics heat storage body.

FIG. 4 is an explanatory diagram showing an example of a heat storage type burner system using a heat storage body.

FIG. 5 is an explanatory view showing a temperature distribution state of the heat storage body, (A)
Shows the decomposition state of the heat storage body, and (B) shows the temperature distribution of the heat storage body.

[Explanation of symbols]

 3 heat storage body 3a-3e heat storage body block

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryoichi Tanaka 2-53, Shitte, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Furnace Industry Co., Ltd.

Claims (5)

[Claims] 1. A heat storage body for imparting sensible heat of a high temperature gas to a low temperature gas by alternately passing a high temperature gas and a low temperature gas from opposite directions in a short time, wherein the heat storage bodies are plural in at least a fluid flow direction. A heat storage body characterized by being divided into. 2. The heat storage body according to claim 1, wherein the divided heat storage body is made of a different material for the hot gas introduction port side and for the low temperature gas introduction port side. 3. The heat storage body according to claim 1, wherein the divided heat storage body has a different structure for a portion close to a high temperature gas inlet and a portion close to a low temperature gas inlet. . 4. The heat storage resistance according to claim 1, wherein the divided heat storage bodies carry an exhaust purification catalyst in a catalytic reaction temperature region. 5. An air throat of a regenerative combustion type burner that burns using high temperature combustion air obtained by alternately passing fuel exhaust gas and combustion air through a flow path switching means to a heat storage body. A heat storage body, wherein a part of the divided heat storage body according to any one of claims 1 to 4 is installed inside, and the rest is installed near the flow path switching means outside a burner.