JPH0361086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of operating a combustion apparatus including a combustion exhaust gas cooling section integrally with a combustion furnace, and a combustion apparatus.

[Conventional technology]

Conventionally, in combustion furnaces equipped with a flue gas cooling section that cools the flue gas discharged from the combustion furnace, such as a boiler, air preheater, or water spray gas cooling chamber, the flue gas cooling section is separated from the combustion furnace as an independent device. They were installed together and connected to each other by ducts lined with refractory material.

Therefore, a huge installation area is required, and in addition, it is necessary to install a combustion furnace, a connecting duct, a support structure for the combustion exhaust gas cooling section, a walkway for inspection, etc. There were problems such as pressure loss due to turbulence of the exhaust gas flow in the flue such as the entrance of the exhaust gas cooling section, and unavoidable accumulation and adhesion on the duct.

In addition, in order to prevent troubles in the connecting ducts due to dust melting, the temperature of the exhaust gas at the furnace outlet is usually kept at 900 to
It is necessary to cool the exhaust gas to 1000°C, so when exhaust gas is cooled by heat recovery, such as when using an air preheater or boiler, there is a drawback that the amount of recovered heat is reduced accordingly.

Therefore, recently, the combustion exhaust gas cooling unit 2 is placed on top of the combustion furnace 1 as shown in FIG.
Combustion devices that are integrated so that the ceiling of the freeboard section directly serves as the inlet of the combustion exhaust gas cooling section 2 are being put into practical use.

As a result, the installation area of the equipment for the combustion exhaust gas cooling section is completely unnecessary, there are no connecting ducts, the support frame is only needed for the combustion furnace, and the inspection walkway is only the one that protrudes from the combustion furnace and cooling section casing. In time, there was almost no turbulence in the flow of combustion exhaust gas, which reduced ventilation pressure loss of combustion exhaust gas, dust accumulation and adhesion, reduced maintenance problems, and reduced the power required for ventilation.

[Problem that the invention seeks to solve]

However, the combustion furnace 1 and the combustion exhaust gas cooling section 2
When integrated, a large amount of heat is transferred from the combustion furnace 1 in the form of radiation to the flue gas cooling section 2, resulting in a decrease in the temperature inside the combustion furnace 1, which may be advantageous for certain combustion materials. However, it was rather inconvenient for other combustion materials, and in some cases such an integrated furnace could not be used.

In other words, in the case of combustible materials with a high calorific value, the cooling load on the furnace is reduced by water spraying at the top of the furnace, cold air injection, etc., and furthermore, when a boiler or air preheater is used to cool the combustion exhaust gas, the cooling load on the furnace is reduced. This is advantageous in that the amount of heat that can be recovered increases by the amount of heat that is not required, and there is no need to increase the heat transfer area of the boiler or air preheater because a large amount of heat is transferred by radiation.
In addition, since the cooling load on the furnace is reduced, the amount of exhaust gas airflow is also reduced, and there is the advantage that the capacity of all exhaust gas-related equipment such as exhaust gas treatment equipment, exhaust gas ventilation power, and chimney diameter can be reduced.

On the other hand, however, in the case of combustible materials with a low calorific value or during partial load operation, the inside of the combustion furnace is cooled by heat transfer from the flue gas cooling section, and the inside of the furnace is cooled to perform combustion and decompose harmful substances and bad odors. In order to maintain the temperature, there is a problem in that it becomes necessary to use or increase the amount of combustion improver.

In particular, in order to remove harmful organic chlorine compounds such as dioxins and benzpyrene, which have recently become a problem, it is necessary to decompose them by heating at a temperature higher than the decomposition temperature. However, these compounds such as dioxins have a high decomposition temperature of 900 to 1200°C, so it is difficult to apply this high temperature due to the melting and adhesion of dust in the flue gas flow path and the heat resistance of the materials. I had it.

The present invention solves the above-mentioned conventional problems, and provides a combustion furnace that does not require a combustion improver even when the calorific value is low, and that does not require dust welding in the flue gas flow path or material selection problems while performing high-temperature combustion. The object of the present invention is to provide a method for operating a combustion apparatus and a combustion apparatus in which a combustion apparatus and a combustion exhaust gas cooling section are integrated.

[Means for solving problems]

As a means to solve the above-mentioned problems, the present invention provides a method for operating a combustion apparatus that integrates a combustion furnace and a combustion exhaust gas cooling section, in which the amount of heat transferred from the combustion furnace to the combustion exhaust gas cooling section by radiant heat transfer is reduced by combustion. A method of operating a combustion device characterized in that the temperature inside the combustion furnace is adjusted by constantly adjusting the heat passage area according to the temperature inside the furnace, and a combustion device in which the combustion furnace and the combustion exhaust gas cooling section are integrated, An area that shields radiant heat transfer from the combustion furnace to the combustion exhaust gas cooling section in the combustion exhaust gas flow path near the connection between the combustion furnace and the combustion exhaust gas cooling section can be constantly adjusted according to the temperature inside the combustion furnace. It is an object of the present invention to provide a combustion device characterized by being provided with a radiation heat transfer shield.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, a combustion exhaust gas cooling section 2, which is a radiation heat transfer surface of a gas cooling chamber, a boiler, an air preheater, etc., is integrally placed on top of a combustion furnace 1. The connecting part between the combustion furnace 1 and the flue gas cooling unit 2 has a nearly rectangular cross section, and in the flue gas flow path in the vicinity thereof, three groups of movable blades with approximately the same cross section in the lateral direction provide radiation heat transfer shielding. It is installed as a body. The movable blade 3 is a plate-shaped member whose width is large relative to its thickness, and is supported at one or both ends in the longitudinal direction by a rotating shaft 4 that penetrates the furnace wall. The rotating shaft 4 is connected to a driving machine 5 outside the furnace, and can be rotated by remote control using a signal.

The movable blade group 3 has a so-called area where the area for shielding radiation heat transfer due to the rotation of each rotating shaft 4, that is, the projected area with respect to the connection surface between the combustion furnace 1 and the combustion exhaust gas cooling section 2 changes greatly, and the projected area is the maximum. In the closed state, the projection surfaces are spaced apart in the horizontal direction so that they cover almost the entire connection surface. In addition, the heights are alternately staggered so as not to block the combustion exhaust gas flow path even in the closed state, so that the outflow of the combustion exhaust gas from the combustion furnace 1 is not obstructed, and therefore no pressure loss occurs. It is made so that there is no The so-called open state with a small projected area can be obtained by rotating the rotation axis 4 by about 90 degrees with respect to the closed state.

The movable blade 3 may be a single plate, but in order to reduce the stress caused by the temperature difference between the surface facing the combustion furnace 1 and the surface facing the combustion exhaust gas cooling section 2, it may be made of a porous body, a multi-plate, or hollow. is preferred. This also helps improve the ability to block radiant heat. Also,
Particularly, the surface of the movable blade 3 facing the combustion furnace 1 reaches a temperature close to the temperature inside the furnace due to the heat from the combustion furnace 1, and it also radiates heat and returns the received heat to the inside of the furnace. Effective in maintaining high temperature inside. Therefore, from the viewpoint of maintaining high temperature, it is better to use a refractory material that can withstand the temperature inside the furnace and not provide a cooling mechanism, but it may be possible to allow a cooling medium to flow through it as necessary.

Furthermore, since it is thinner than its width and has a wing-like shape that is long in the lateral direction, and also rotates, it is subject to vibration and distortion, and is subject to its own weight and thermal stress, so it must also have mechanical strength. Therefore, the rotary shaft 4 may be water-cooled or air-cooled, and a movable blade 3 made of a refractory material wing section divided into several parts may be attached to it, or the rotary shaft 4 may be made of silicon carbide-based or silicon nitride-based ceramic having mechanical strength. and a movable wing 3.
When made of ceramic, β-SiC is particularly preferred as it has excellent properties such as mechanical strength at high temperatures, thermal shock resistance, heat resistance, and oxidation resistance.

Therefore, the radiation heat transfer to the combustion exhaust gas cooling section 2 of the combustion furnace 1 can be adjusted steplessly by rotating the group of movable blades 3. Therefore, the combustion temperature is detected by the temperature regulator 6 which detects the temperature inside the combustion furnace 1 and outputs an operation signal to the drive unit 5. When the temperature is high, the combustion temperature is detected, and when the temperature is low, the signal to open is sent to the three groups of movable blades. Send it to the driving machine 5 and rotate the 3 groups of movable blades as appropriate to change the area that blocks radiation heat transfer from the combustion furnace 1 to the flue gas cooling section 2, thereby adjusting the inside of the combustion furnace 1 to a predetermined temperature. becomes possible.

That is, when the three groups of movable blades are closed, most of the radiant heat from inside the combustion furnace 1 is blocked by the three groups of movable blades. The surface of the three groups of movable blades facing the incinerator 1 has a high temperature similar to that inside the combustion furnace 1, and radiates heat close to the amount of heat received and returns it to the combustion furnace 1. That is, the three groups of movable blades act like a heat reflector. In the open state, radiant heat enters the combustion exhaust gas cooling section 2 through the gap. Since this part is cooled, no heat returns to the combustion furnace 1,
The combustion furnace 1 will be cooled. Since the radiant heat from the combustion furnace 1 increases in proportion to the fourth power of the absolute temperature, the effect of suppressing the temperature inside the furnace is large. By steplessly adjusting the size of this gap, the temperature inside the furnace can be easily adjusted.

Furthermore, even if high-temperature flue gas immediately flows into the flue gas cooling unit 2 when the combustion furnace 1 is at a high temperature, if the combustion furnace 1 is at a high temperature, the movable blades 3
Since the radiant heat transfer from the combustion exhaust gas cooling section 2 has sufficient cooling capacity,
As soon as it flows in, it is rapidly cooled down. Therefore, even if combustion is performed at such high temperatures that some of the fly ash contained in the flue gas melts or begins to sinter, the flue gas is cooled as soon as it moves to the flue gas cooling section 2 to a temperature at which it no longer sticks. The temperature drops immediately, and high-temperature combustion is possible because it does not adhere to the combustion exhaust gas passage and block the passage or form scale on the cooling heat transfer surface of the combustion exhaust gas cooling unit 2 or the nozzle, causing trouble or a reduction in performance. . Therefore, in the case of municipal waste incineration, there was a risk that flame-retardant toxic organic chlorine compounds such as dioxins would not be decomposed at conventional combustion temperatures of 950℃ or lower, but by incinerating them at temperatures of 1000 to 1200℃ or higher, These harmful substances can also be decomposed and removed.

In addition, if the combustion furnace 1 is a fluidized bed combustion furnace, the combustion rate in the fluidized bed is suppressed to 800 to 850℃ or less, and if the combustion is performed at 1000 to 1200℃ or higher in the freeboard part of the upper space, the hearth also Conventional products can be used.

In addition, even in the case of a combustible material with a low calorific value or in partial load operation, the 3 groups of movable blades are closed to prevent heat from escaping from the combustion furnace 1 and the combustion exhaust gas cooling section 2
Since it is possible to prevent cooling caused by combustion, it is possible to obtain a high temperature without adding a combustion improver.

Although the movable blade 3 has been described above as an example that can cover almost the entire projection surface, the radiation heat transfer shield does not necessarily have to cover the entire projection surface in the maximum shielding state.

〔Effect of the invention〕

The present invention constantly adjusts the amount of heat transferred from the combustion furnace to the flue gas cooling section by radiation heat transfer according to the temperature inside the combustion furnace by the heat passage area, thereby adjusting the temperature inside the combustion furnace. It prevents heat leakage, enables stable operation without lowering the temperature inside the combustion furnace, and enables high-temperature combustion depending on the condition of the incinerated material, making it easy to decompose and remove flame-retardant toxic substances. It can effectively handle partial load operation, eliminates or saves heat additives even when the calorific value is low, and can reduce dust welding in the flue gas flow path and material selection while performing high-temperature combustion. It is possible to provide a method for operating a combustion device and a combustion device without any problems, and it is possible to achieve significant practical effects.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a flow diagram, FIG. 2 is a sectional plan view taken along the line of FIG. 1, and FIG. 3 is a front view of a conventional example. 1... Combustion furnace, 2... Combustion exhaust gas cooling section, 3...
...Movable wing, 4...Rotating shaft, 5...Driver, 6...
air conditioner.

Claims (1)

[Claims] 1. In a method of operating a combustion device that integrates a combustion furnace and a combustion exhaust gas cooling section, the amount of heat transferred from the combustion furnace to the combustion exhaust gas cooling section by radiation heat transfer is controlled according to the temperature inside the combustion furnace. A method of operating a combustion apparatus, characterized in that the temperature inside the combustion furnace is adjusted by constantly adjusting the heat passage area. 2. In a combustion device that integrates a combustion furnace and a combustion exhaust gas cooling section, radiant heat transfer from the combustion furnace to the combustion exhaust gas cooling section occurs in the combustion exhaust gas flow path near the connection between the combustion furnace and the combustion exhaust gas cooling section. 1. A combustion device characterized by being provided with a radiation heat transfer shield whose area for shielding can be constantly adjusted according to the temperature within the combustion furnace. 3. The combustion apparatus according to claim 2, wherein the radiation heat transfer shield is a movable blade.