JPS6319706Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a fluidized bed incinerator, and particularly to a fluidized bed incinerator suitable for volume reduction incineration of heavy crude oil ash. Heavy _crude oil ash usually consists of _unburned carbon, ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), _and ash _{. 2} O ₃ ), etc. For this reason, when heavy crude oil ash is burned in a fluidized bed incinerator, ammonium sulfate decomposes and ammonia (NH ₃ ) is generated, and NH ₃ is further converted to nitrogen oxides (NOx), which are added to the gas at the fluidized bed outlet. The amount of NOx and NH ₄ increases significantly. Also, when vanadium pentoxide and Glauber's salt are combined at a certain ratio, a low melting product is formed.
If air containing these incineration residues is sent into the flue at a high temperature, there is a problem that the low-melting substances will adhere to the duct. Further, there is a problem in that unburned carbon contained in the combustion gas becomes red-hot in the exhaust gas duct or the dust collector, causing so-called hot combustion, resulting in a burnout accident. In order to solve this problem, conventionally an air nozzle was installed near the top of the fluidized bed incinerator, and air was injected into the furnace from this air nozzle to raise the temperature in the upper part of the furnace to 350℃ to 450℃. It was cooling down. However, according to this method, since the amount of exhaust gas increases, a problem arises in that the capacity of the dust collector, induced draft fan, etc. installed on the downstream side of the exhaust gas increases. In addition, a part of the cooling air injected into the furnace from the air nozzle descends along the inner wall of the furnace, reaches the lower part of the fluidized bed incinerator, and mixes with the combustion gas, causing a so-called back mixing phenomenon. become. As a result, the temperature of the combustion gas in the lower part of the fluidized bed incinerator decreases, so there is a problem that the amount of auxiliary fuel in the cylinder burner increases in order to maintain the temperature inside the incinerator at an appropriate condition. Furthermore, when the fluidized bed outlet is kept at a high temperature, NOx present near the fluidized bed outlet reacts with NH ₃ in the gas phase and is reduced. However, as a result of the back mixing phenomenon,
Because the temperature distribution in the furnace height direction becomes uneven,
There is a problem that NOx reduction is not sufficiently achieved. Moreover, when the unreacted residual NH ₃ that did not contribute to NOx reduction in the cavity reaches near the top of the furnace,
There is a problem in that NOx is newly generated by reacting with O ₂ in the cooling air. The purpose of this invention is to reduce the amount of NOx emissions while preventing problems caused by low melting substances in the incineration residue on the flue duct when incinerating substances containing nitrogen compounds and low melting substances. . The purpose of the present invention is to provide a fluidized bed incinerator. In order to achieve the above object, the present invention provides a fluidized bed incinerator for incinerating materials containing ammonia component-containing materials and low-melting materials. It consists of a fluidized bed section that performs fluidized combustion at a low temperature, and a hollow cylinder section placed above the fluidized bed section.
A sky tower burner and a secondary air supply means are provided to maintain the gas phase reduction reaction temperature of NOx by NH ₃ , and a water spray whose water spray direction is approximately horizontal is provided near the furnace top located at the upper part of the cavity. The reason is that a nozzle is provided. In other words, by burning at a low temperature in the fluidized bed section, the conversion of _NH3 generated during combustion into NOx is suppressed as much as possible, and in the subsequent cavity section, the NH3 generated in the fluidized bed section is maintained at a reduction temperature. Due to the ring element reaction between NH ₃ and NOx
In addition to reducing NOx, the combustion gas is cooled by water spray using horizontal spraying, thereby preventing back mixing and maintaining the temperature distribution in the furnace height direction in the cavity uniformly at the reduction temperature, thereby reducing NOx. By ensuring a sufficient range of reducing atmosphere and at the same time preventing the generation of NOx due to residual NH ₃ and O ₂ that occur when cooling with air, NOx emissions can be reduced, and the flue duct due to low melting materials can be reduced. This prevents adhesion problems. The present invention will be described below based on embodiments shown in the accompanying drawings. FIG. 1 is a schematic configuration diagram showing an example of the present invention, in which a wind box 3 is formed below a dispersion plate 2 provided at the bottom of an incinerator body 1, and a wind box 3 is formed on the dispersion plate 2. A heavy crude oil ash supply nozzle 8 and an in-bed burner 9 are attached to the fluidized bed 4. An empty tower burner 14 is attached to the cavity 6 above the fluidized bed 4, and several secondary air headers 11 are provided above the installation position of the empty tower burner 14 so as to surround the furnace wall. Several water spray nozzles 12 are provided in one stage in the furnace height direction in the circumferential direction near the furnace top located at the upper part of the hollow cylindrical portion 6. In such a device, the fluidizing air 7 passes through the wind box 3 and the distribution plate 2 and fluidizes the fluidizing medium consisting of silica sand, forming a fluidized bed 4. fluidized bed 4
An auxiliary fuel oil is supplied from an in-bed burner 9 to the fluidized bed 4, and the temperature inside the fluidized bed 4 is kept constant at all times by fluidized air. In this fluidized bed, heavy crude oil consisting of unburned carbon, ammonium sulfate, and ash is fed to the heavy crude oil ash supply nozzle 8.
Supplied by In the fluidized bed 4, ammonium sulfate in the heavy crude oil ash decomposes to generate ammonia, which is further converted to NOx, and the NOx at the outlet of the fluidized bed 4 is
The amount increases significantly. Therefore, the temperature in the fluidized bed 4 (indicated by T ₁ in the figure) is maintained at a sufficiently low temperature within a range that does not hinder the combustion of heavy crude oil ash.
Adjusted to suppress NOx production. That is, the temperature is adjusted to a temperature that can suppress the conversion of ammonia NH ₃ to NOx as much as possible. Next, the air introduced from the secondary air header 11 via the line 10 and the auxiliary fuel oil supplied from the hollow cylinder burner 14 cause the temperature near the outlet 5 of the fluidized bed 4 and the hollow cylinder part 6 to rise (in the figure). , T ₂ , T ₃ ) are maintained at high temperatures. As a result, NOx contained in the gas discharged from the fluidized bed 4 reacts with NH ₃ in the gas phase and is reduced. Further, in the hollow cylinder portion 6, unburned carbon in the form of extremely fine particles is burned in the gas phase. In the incineration residue rising inside the hollow cylinder 6, there is a low melting material generated by vanadium pentoxide (V ₂ O ₅ ) and Glauber's salt (NaSO ₄ ). However, this low-melting material is cooled by the water jetted from the water jet nozzle 12 and loses its stickiness as it is cooled by the heat corresponding to the latent heat of the water. This can prevent the incineration residue discharged from the flue 13 from adhering to the inner wall surface of the flue 13. According to the water spraying means according to the present invention, the temperature distribution in the height direction of the incinerator is uniform. FIG. 2 is a graph qualitatively showing the temperature distribution in the height direction of the incinerator in the case of the conventional air spraying means and the water spraying means of the present invention. In FIG. 2, 1 indicates the temperature distribution during water injection, and 2 indicates the temperature distribution during air injection.
In the case of air injection, the temperature distribution is non-uniform, and the influence of so-called back mixing is considered. In the case of water injection, there is no temperature change over the entire furnace height above the fluidized bed 4, and therefore the temperature distribution is uniform. This means that the gas phase reduction of NOx is effectively carried out, and NOx
This shows that it is effective in reducing Moreover, even if unreacted residual NH ₃ reaches the high-temperature atmosphere at the boundary of the cooling zone caused by water spray, no new NOx will be generated because it is not O ₂ rich. If water is sprayed upward here, droplets will scatter on the exit wall and wet the wall surface, causing adverse effects such as the formation of deposits and corrosion of the wall material.Also, the cooling of low-melting point substances may be uneven due to gas blow-through, etc. Become.
On the other hand, if water is sprayed downward, the temperature of the empty column will be lowered, impairing the denitrification effect and the effect of reducing auxiliary fuel oil. Therefore, it was found that it is best to spray water horizontally. Next, in order to clarify the effects of the present invention, the performance of the present invention and a conventional fluidized bed incinerator using air injection were compared when operated in a plant with a processing capacity of 300 kg/h of heavy crude oil ash. Processing amount of heavy crude oil ash,
The amount of exhaust gas, amount of NOx in the exhaust gas, and consumption of auxiliary fuel oil (oil) were investigated while keeping the fluidized bed temperature and cavity temperature constant. The results are shown in Table 1.

[Table] According to the above table, the water injection means can reduce the amount of exhaust gas, the amount of NOx in the exhaust gas, and the amount of fuel oil consumed compared to the air injection means. in exhaust gas
Although the NOx reduction rate is low, the amount of exhaust gas generated has been significantly reduced, which means that the NOx amount reduction effect is large based on the total amount standard. As described above, according to the present invention, it is possible to reduce the amount of NOx emissions and eliminate the problem of incineration residue adhesion in the flue duct without increasing the amount of exhaust gas or the amount of auxiliary fuel consumed.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram showing an example of the present invention;
The figure is a graph qualitatively showing the temperature distribution in the direction of the furnace height. 2... Dispersion plate, 3... Wind box, 4... Fluidized bed, 6
... Cylinder section, 8 ... Heavy crude oil supply nozzle, 9 ... In-bed nozzle, 11 ... Secondary air header, 12 ... Water spray nozzle, 13 ... Flue, 14 ... Sky tower burner.

Claims (1)

[Scope of utility model registration request] In a fluidized bed incinerator that incinerates substances containing ammonia component-containing substances and low-melting substances, this fluidized bed incinerator includes a fluidized bed part that performs fluidized combustion at a low temperature that does not interfere with maintaining combustion of the substances. ,
and a cavity disposed above the fluidized bed, and a cavity located upstream of the combustion gas in the cavity to maintain the temperature of the cavity at the temperature of the gas-phase reduction reaction of NOx by _NH3 . A fluidized bed incinerator characterized in that a burner and a secondary air supply means are provided, and a water spray nozzle that sprays water in a substantially horizontal direction is provided near the top of the furnace located in the upper part of the cavity.