JPH08121712A - Method and device for regenerative combustion - Google Patents

Abstract

PURPOSE: To suppress the evolution of NOx effectively by a method wherein, after stabilizing the flame of combustion using air of normal temperature, the combustion reaction is made to take place inside the furnace and is continued in a manner of slow combustion, into which the combustion gas inside the furnace is drawn. before meeting high-temperature air and with the partial pressure of oxygen in a reduced state by using the high-temperature air on the other hand. CONSTITUTION: A gas-feeding part 3 having the forward end opening into the inside of a furnace 2 is provided. At the forward end of this gas-feeding part 3 a flame-stabilizing part 4 is provided. At the periphery of the gas-feeding part 3 a normal-temperature-air-feeding part 5 for stabilizing the flame, having the forward end opening into the inside of the furnace 2, is provided. Around the periphery of this normal-temperature-air-feeding part 5 for stabilizing the flame a plurality of preheated-high-temperature-air-feeding parts 6 having the forward ends opening into the inside of the furnace 2 are provided and filled with heat accumulator 7. By injecting high-temperature air in divided currents through a plurality of air holes 12 these preheated-high-temperature-air-feeding parts 6 improve the flame-stabilization efficiency and the combustion in stability. Regenerative burners of this constitution are set opposite to each other in the furnace body 1 and their operation is so controlled as to make them alternate the regenerative combustion repetitively between the two.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage combustion method and apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 1, a typical example of a conventional heat storage and combustion apparatus is one in which a burner section and a heat storage section are integrally formed and attached to a furnace body for alternate switching combustion. Such an apparatus achieves high heat efficiency by collecting waste heat by collecting air from the sensible heat of exhaust gas and then preheating it. Further, as shown in FIG. 2, a device for performing two-stage combustion using a heat exchanger causes excessive fuel combustion by primary air in the first stage, and in the second stage, secondary air is newly added into the furnace. It is for injecting to perform lean fuel combustion. That is, in the first stage, a reducing combustion region is created by burning in the burner combustion chamber. Therefore, it has an effect of suppressing conversion to fuel NOx. Further, since the combustion temperature is suppressed, thermal NOx is suppressed. Then, a flame with high brightness (emissivity) is formed by the reduction combustion in the first stage.

[0003]

Among the above-mentioned conventional apparatuses, in the apparatus shown in FIG. 1, the burner section allows high-temperature exhaust gas to pass therethrough or generates high-temperature flame. Requires lining. Further, since the tip of the fuel supply unit is exposed to high temperature, there is a risk of burnout, and in order to avoid this, air cooling or water cooling is necessary. Further, the structure of the entire equipment becomes complicated and large, so that the equipment cost becomes high, and the high-temperature air preheating combustion causes extremely high NOx emission level. In the conventional apparatus shown in FIG. 2, the two-stage air combustion is effective in reducing the fuel NOx, but not so effective in suppressing the thermal NOx. Therefore, like the heat storage combustion, In case of high temperature preheated air combustion, thermal NOx increases and cannot be used.
In order to form the reducing combustion region, the existence of the primary combustion chamber is indispensable and the burner must be large.

[0004]

In order to solve the above-mentioned problems, the present invention provides a burner shaft with a gas supply part having a tip opening into the furnace, and a flame holding part at the tip part of the gas supply part. A flame holding room temperature air supply section is provided on the outer periphery of the gas supply section, the tip of which is opened into the furnace, and the tip of the flame holding room temperature air air supply section is opened into the furnace. A high temperature preheated air supply section is provided, and the high temperature preheated air supply section is provided with a pair of regenerative burners filled with a heat storage body.
Depending on the furnace body conditions, a suitable number of pairs are installed in the furnace body and alternately burned, and when the flame holding flame is formed in the flame holding portion, the inside of the furnace is fed from the high temperature preheating air supply portion. The present invention provides a heat storage combustion method characterized in that high-temperature air is supplied to.

In order to solve the above-mentioned problems, the present invention provides a burner shaft with a gas supply part having a tip opening into the furnace, and a flame holding part at the tip part of the gas supply part. A flame holding air supply unit is provided on the outer periphery of the flame holding air opening unit, the tip of which is opened into the furnace, and a high temperature preheating air supply unit whose tip is opened into the furnace is provided on the outer periphery of the flame holding air air supply unit. , A high temperature preheated air supply unit is provided with a pair of regenerative burners, which are filled with a heat storage body, in an appropriate number of pairs in the furnace body according to the conditions of the furnace body. To do.

In order to solve the above-mentioned problems, the present invention provides a heat storage combustion device characterized in that the tip end portion of the heat storage chamber is formed as a tapered portion.

In order to solve the above problems, the present invention provides a heat storage and combustion device characterized in that the heat storage chamber is wholly or partially located inside the furnace wall.

In order to solve the above-mentioned problems, the present invention is characterized in that the pilot burner is located in the vicinity of the flame holding portion through the flame holding room temperature air supply portion. Is provided.

[0009]

On the side of the regenerative burner A, when the fuel gas is introduced into the gas supply section, it is mixed with the air supplied from the flame holding room temperature air supply section in the vicinity of the downstream side of the flame holding section. , Start burning in the furnace. This combustion is combustion with normal temperature air, and since the combustion reaction after flame holding is performed in the furnace, it becomes a slow combustion by involving the combustion gas in the furnace before encountering the high temperature air described later, The production of NOx is effectively suppressed. At the time of this combustion, the high temperature preheated air was blown from the high temperature preheated air supply section by the heat storage body at a high speed from the front constriction section, so a large amount of combustion gas in the furnace was entrained and the oxygen partial pressure decreased. In this state, the combustion reaction progresses, and the NOx combustion is continued while the flame is favorably maintained by the slow combustion described above. A plurality of air holes are provided in the high temperature preheated air supply unit, and when hot air is ejected from the air holes, the flame becomes more stable and flapping of the flame can be prevented. The high temperature air is exhausted through the regenerative burner B side at high temperature, but at that time, the heat storage body is preheated. Regenerative bar with the above combustion and exhaust
On the A side, the combustion device, and the regenerative burner B side, for example, it is repeated alternately every tens of seconds to several minutes.

[0010]

EXAMPLE A gas supply section 3 having a tip opening in the furnace 2 is provided, a flame holding section 4 is provided at the tip of the gas supply section 3, and a flame holding room temperature is provided on the outer periphery of the gas supply section 3. An air supply unit 5 is provided and its tip is opened into the furnace 2. A plurality of high-temperature preheated air supply units 6 having tips open into the furnace 2 are provided on the outer periphery of the flame holding room temperature air supply unit 5, and the high-temperature preheated air supply unit 6 is filled with a heat storage body 7. When the high temperature preheated air supply unit 6 jets out a high temperature in a divided manner by the plurality of air holes 12, flame holding performance is improved and stable combustion can be performed. A suitable number of regenerative burners A and B having the above-described structure are installed in the furnace body 1, and heat storage combustion is alternately repeated. During this combustion, when the flame holding flame 13 is formed in the flame holding portion 4, the high temperature preheated air supply portion 6 supplies high temperature air to the furnace 2. A tip portion of the high temperature preheated air supply portion 6 is formed as a pre-throttled portion 8. In addition, all or part of the high temperature preheated air supply unit 6 is configured to be located inside the furnace wall 9. The heat storage body 7 is a ceramic or metal ball-shaped material, a honeycomb-shaped material, fins or mesh-shaped materials made of them, or a combination thereof. The pilot burner 10 is arranged so as to be located in the vicinity of the flame holding unit 4 via the flame holding room temperature air supply unit 5.

On the side of the regenerative burner A,
When the fuel gas is introduced into the gas supply unit 3, it mixes with the air supplied from the flame holding room temperature air supply unit 5 in the vicinity of the downstream side of the flame holding unit 4 to form the flame holding flame 13 in the furnace. . This combustion is combustion with normal temperature air that does not pass through the heat storage body 7. Further, since the combustion reaction after flame holding is performed in the furnace 2,
Since the in-furnace combustion gas 14 is engulfed and the combustion becomes slow before the hot air described later is encountered, generation of NOx is effectively suppressed. At the time of this combustion, the high temperature preheated air is blown from the high temperature preheated air supply section 6 by the heat storage body 7 at a high speed from the preconstriction section 8, so that a large amount of the combustion gas in the furnace is entrained and the oxygen partial pressure The combustion reaction proceeds in a state where the NOx is decreased, and NOx combustion is continued while the flame is favorably maintained by the slow combustion described above. A plurality of air holes 12 are provided in the high-temperature preheated air supply unit 6, and when the air is ejected from the air holes 12 at a high temperature, the wake effect of the combustion gas 14 in the furnace is increased and the generation of NOx is further promoted. In the above combustion, if the pilot burner 10 is arranged so as to be located in the vicinity of the flame holding part 4 via the flame holding room temperature air supply part 5, it is cooled by the flame holding air, It is not only necessary to use the cooling pipe, but also because the pressure fluctuation is extremely small, a stable pilot flame can be formed. Exhaust is regenerative burner B
At the time of high temperature, the air is exhausted through the air circulation portion 6, but at that time, the heat storage body 7 is preheated. The above combustion and exhaust are alternately repeated on the regenerative burner A side and the regenerative burner B side, for example, every several tens of seconds to several minutes. As described above, in the case of the present invention, since air and fuel gas are directly jetted into a wide furnace space, unlike a normal combustion method in which air and fuel are jetted and burned in a narrow space inside a burner. , A large amount of gas in the furnace can be suction-mixed with each jet. Further, a part or all of the heat storage body 7 is a furnace wall 9
Since it is located inside, the exhaust gas temperature inside the furnace wall 9 becomes low, and there is a great advantage that the lining of the fireproof heat insulation of the heat storage section 4 is unnecessary. Further, in the present invention, since the combustion is as described above, it is not necessary to provide the burner section and the heat storage section as shown in FIG. 1, and as shown in FIG. There is also a great merit that the entire apparatus can be made compact because it does not adopt a configuration that executes combustion.

[0012]

As described above, the present invention has the following effects. Combustion with normal temperature air, and since the combustion reaction after flame holding is performed in the furnace, the combustion gas in the furnace is engulfed before it encounters the high temperature air, resulting in slow combustion, so the generation of NOx is effective. At the same time
The combustion reaction proceeds in a state where the oxygen partial pressure due to the high temperature air is reduced, and the low NOx combustion is maintained while the flame is favorably maintained by the slow combustion described above, so that the generation of NOx is effectively suppressed. Since the burner tile surrounding the flame is not required to generate the flame directly in the furnace and the heat storage body is located inside the furnace wall, the exhaust temperature after leaving the heat storage body is low and the fire resistance of the heat storage section is low. Insulation lining is unnecessary and heat loss is small. The gas supply part, pilot burner, flame detector, etc. are cooled by cooling with room temperature air for flame holding, so no special cooling pipes are required, equipment costs can be reduced, and pilot flame is Since it is formed in a position where there is little fluctuation and in which the flow velocity is slow, there is no concern that the pilot flame will be blown out. Since a two-stage combustion system that adopts 4 reduction combustion is not adopted, no combustion chamber is required, and the entire structure can be made compact. In addition, since the combustion in the flame holding part is cold air combustion with normal temperature air, the flame temperature is kept low, and the combustion of the flame holding part and the fuel supply part can be avoided.
In addition to improving reliability, heat is effectively stored in the furnace wall, resulting in significantly improved thermal efficiency. Since there is no need to switch the gas depending on the furnace temperature, it can be used with low NOx at any furnace temperature, and since the room temperature air is used as the flame holding air, the flame holding part is cooled and burned. There are no concerns.

[0013]

[Brief description of drawings]

FIG. 1 is an explanatory view of a conventional heat storage combustion device.

FIG. 2 is an explanatory diagram of a conventional heat storage combustion device.

FIG. 3 is a cross-sectional explanatory view of a main part of the device of the present invention.

FIG. 4 is an overall explanatory view of the device of the present invention.

[Explanation of symbols]

 1 Furnace Body 2 Furnace 3 Gas Supply Section 4 Flame Retaining Section 5 Flame Retaining Room Temperature Air Supply Section 6 High Temperature Preheated Air Supply Section 7 Heat Storage Body 8 Throttling Section 9 Furnace Wall 10 Pilot Burner 11 Flame Detector 12 Air Hole 13 Flame holding flame 14 Combustion gas in furnace

Claims (5)

[Claims] 1. A burner shaft is provided with a gas supply section having a tip opening into the furnace, a flame holding section is provided at the tip of the gas supply section, and a flame holding room temperature air supply is provided on the outer periphery of the gas supply section. Part is provided, the tip of which is opened in the furnace, and the high temperature preheated air supply part whose tip is opened in the furnace is provided on the outer periphery of the flame holding room temperature air supply part, and the high temperature preheated air supply part is , A pair of regenerative burners filled with a heat storage body are installed in the furnace body in appropriate pairs according to the furnace body conditions and alternately burned, and flame holding flame is formed in the flame holding portion. The high temperature preheated air supply unit is supplying high temperature air into the furnace during the operation. 2. A burner shaft is provided with a gas supply section having a tip opening into the furnace, a flame holding section is provided at the tip of the gas supply section, and a flame holding room temperature air supply is provided on the outer periphery of the gas supply section. A part is provided, the tip of which is opened into the furnace, and the high temperature preheated air supply part whose tip is opened into the furnace is provided on the outer periphery of the flame holding room temperature air air supply part, and the high temperature preheated air supply part Is a pair of regenerative burners filled with heat storage
A heat storage and combustion device characterized in that an appropriate number of pairs are installed in the furnace body according to the furnace body conditions. 3. The heat storage combustion apparatus according to claim 2, wherein the tip of the heat storage chamber is a tapered portion. 4. The heat storage combustion apparatus according to claim 2, wherein the heat storage chamber is wholly or partially located inside the furnace wall. 5. The heat storage combustion apparatus according to claim 2, wherein the pilot burner is located near the flame holding portion via a flame holding room temperature air supply portion.