JPS6118087B2 - - Google Patents

Description

[Detailed description of the invention]

This invention processes organic chlorides with a chlorine concentration of about 10 to 70%, which are disposed of from polymer polymerization reaction processes or similar processes, whether in liquid, slurry, or solid form. The present invention relates to a method of incineration without causing any trouble using a fluidized bed furnace. When organic chlorides with high chlorine concentrations are incinerated in the usual way, the combustion gas contains several hundred to 20,000 to 30,000 chlorides.
A large amount of chlorine gas on the order of 10,000 ppm is generated.
This chlorine gas is harmful and its release is strictly regulated, so it is necessary to add chemicals to make it harmless before releasing it, but since the amount of chlorine gas is large, the amount of chemicals used is also large, which increases costs. There is also the problem that the service life of the furnace and accessories is reduced. For this reason, water or an aqueous solution (hereinafter referred to as
Abbreviated as water. ) is mixed within a natural range and burned, and water is directly sprayed into the combustion flame, thereby reducing the amount of chlorine gas generated and suppressing the combustion temperature to 1250℃ or less. It was proposed in 1973-17371. In this prior art, the reaction equation for chlorine gas generation is 4HCl + O ₂ 2H ₂ O + 2Cl ₂ , and in order to suppress gas generation, either (1) increase the combustion temperature, (2) increase the partial pressure of water, or ( 3) Since this is possible by lowering the partial pressure of oxygen, in order to increase the partial pressure of water, water is mixed into the organic chloride liquid to the extent that it retains self-flammability, and the resulting combustion flame is Water is directly injected into the fuel to lower the combustion temperature using the latent heat of vaporization of the water, resulting in combustion at a relatively low temperature while suppressing the generation of chlorine gas. However, with this prior art, only liquid organic chlorides can be combusted, and slurry or solid organic chlorides cannot be treated. Furthermore, if this prior art method is carried out using a normal combustion furnace, it is difficult to maintain a uniform combustion gas temperature, resulting in locally high temperatures, which has a negative impact on the lifespan of the furnace and accessories, and also causes chlorine gas to be released. The amount generated will also be higher than expected. Furthermore, organic chlorides contain low melting point compounds such as salts such as sodium and potassium, and the sodium concentration can sometimes reach 30,000 ppm. Even if the combustion temperature is kept to a relatively low salt level, these low melting point compounds adhere to the furnace walls and increase in number, causing combustion troubles. However, this prior art does not take this point into account at all. Therefore, the problem of the present invention is to be able to burn not only liquid but also slurry and even solid organic chlorides without causing trouble due to the low melting point compounds contained in the organic chlorides. This problem was solved by using a fluidized bed type combustion furnace and spraying water into the empty column inside the furnace and into the fluidized bed with a nozzle. That is, the present invention sprays water or an aqueous solution into the furnace when burning organic chlorides in a combustion furnace, thereby improving the contact between the water or aqueous solution and the chlorine gas generated by combustion, and reducing the chlorine gas. In this incineration method for organic chlorides, which reduces chlorine gas in the exhaust gas by converting it into HCl, the combustion furnace is of a fluidized bed type, high-purity silica is used as the fluidized bed medium particles, and water or an aqueous solution is used in the space inside the furnace. At the same time, water or an aqueous solution is also sprayed into the bed of the fluidized bed to promote the scattering effect of the media particles compared to a general fluidized bed, and the media particles are forcibly crushed and pulverized by thermal shock. The low melting point compounds contained in the organic compounds are attached and scattered out of the system, and a sufficient amount of media particles is replenished to compensate for the reduction in scattering, making continuous operation possible and at the same time reducing the organic chloride to solid or slurry form. This invention relates to a method for incinerating organic chlorides, which is characterized by converting chlorine gas into HCl at a relatively low temperature of 750°C to 1050°C, regardless of liquid, mixed combustion, or single combustion. That is, since the present invention uses a fluidized bed combustion furnace, the organic chloride to be incinerated is not limited to liquid, slurry, or solid. It also keeps the temperature constant. By spraying water into the furnace, the combustion temperature can be lowered by the latent heat of vaporization of the water, and the particles constituting the fluidized bed in a fluidized state are crushed by thermal shock and pulverized, and this fine powder is mixed with low melting point compounds. This prevents troubles by attaching and scattering them out of the furnace together with the debris, and preventing low melting point compounds from remaining on the furnace wall of the combustion furnace or causing particles constituting the fluidized bed to form agglomerates and inhibiting the fluidization state. Combustion can be performed without generation. For this reason, it is necessary to replenish the amount of particles into the furnace in a larger amount than in normal combustion in order to compensate for the particles that are pulverized by thermal shock. Although it is necessary to take measures to recover fine powder of scattered particles, according to the present invention, organic chlorides can be incinerated even if they are in liquid, slurry, or even solid form.
It has the excellent effect of being able to burn at extremely low temperatures of 750 to 1050°C, while minimizing the amount of chlorine gas generated, and without the troubles caused by low-melting compounds. The particles constituting the fluidized bed are preferably inert sand with as high a purity as possible, for example, one containing 96% or more of SiO ₂ . The present invention will now be described with reference to the accompanying drawings. 1 is a well-known fluidized bed combustion furnace in which a fluidized bed 3 of inert media particles such as silica sand is formed on a dispersion plate 2; combustion pressure air is blown below the dispersion plate 2; The top of the is the debris collection device 5,
It is connected to a suction source, such as an exhaust fan 7, via an HCl recovery device 6. In order to supply liquid waste or slurry waste, a nozzle 8a for spraying these wastes together with purge air into the fluidized bed is provided in the furnace shell. In the case of solid waste, it is supplied near the upper surface of the fluidized bed, for example, directly above it, using a suitable supply device 9 such as a screw feeder. A nozzle 8b for spraying water together with purge air into the fluidized bed, and a nozzle 8c for spraying water together with purge air inside the empty column are provided. In these nozzles 8c, there is a temperature difference between the fluidized bed and the empty column due to the moisture content of the incinerated material, so in order to correct this, contact between chlorine gas and water is also performed in the empty column. It is for the purpose of Each nozzle 8
As shown in Fig. 3, a, 8b, and 8c are constructed of double pipes consisting of a central passage 10 of a constant diameter through which waste liquid, slurry, and water pass, and an outer peripheral passage 11 surrounding the outer periphery of the central passage. It's a good thing. Note that the tips of the central passage 10 and the outer peripheral passage 11 open on the same plane. Of course, the number of each nozzle is not limited to one; for example, there are six nozzles for spraying liquid waste, with three nozzles in upper and lower stages, and three nozzles for spraying slurry waste, one in a different stage. Also, among the nozzles that spray water, those 8b that spray into the fluidized bed are installed in two different stages, and are distributed radially around the furnace body, so that they are arranged so that the temperature of the combustion gas in the furnace is uniform. do. The furnace operation is the same as a normal fluidized bed combustion furnace, with burner 1.
After ignition in step 3, all that is required is to spray fuel oil into the fluidized bed with an oil gun to assist combustion, if necessary. As a result, the liquid waste sprayed by the nozzle 8a into the fluidized bed, the slurry waste as well, and the feeder 9
The solid waste fed onto the fluidized bed is naturally oxidized, and the chlorine gas generated at this time is brought into sufficient contact with the water sprayed into the fluidized bed by the particles in the fluidized state, and is converted into HCl. At the same time, on the one hand, the combustion gas temperature in the furnace is kept constant (750-1050° C.) by means of the water sprayed into the fluidized bed. Some of the particles that have been sprayed with water are crushed by thermal shock and become fine powder, and the generated low-melting compounds adhere to this fine powder and are sucked out of the furnace. collect. Particles are replenished, for example, from a particle supply port 12 provided after the solid material supply port 9' of the solid material supply device 9. By using a double-pipe nozzle as shown in Figure 3 for the nozzle that sprays liquid or slurry waste or water, especially liquid or slurry waste spouted from the central passage can be removed from the outer periphery. The nozzle is thermally insulated by the air passing through the passage, and the nozzle is not solidified by thermal polymerization or the like within the tip part that protrudes into the furnace, so spraying is carried out constantly. As a result, the amount of chlorine gas generated increases due to fluctuations in the spray condition, and this is included in the combustion gas and exits the furnace.
There is no need to say that the chlorine gas concentration increases. Next, experimental data obtained by carrying out the present invention will be shown. The fluidized bed combustion furnace used has an inner diameter of 1900 mm and a height of
9000 mm, and the particles constituting the fluidized bed have an average particle size of
0.4mm, ingredients are SiO ₂ 95.54%, Al ₂ O ₃ 2.45%,
Fe ₂ O ₃ 0.25%, FeO 0.10%, MgO 0.15%, ignition loss (loss on ignition) 1.3%, other 0.21%
4 tons of sand containing no TiO ₂ , CaO, or Na ₂ O was used for combustion.

[Table] The reduction rate of sand is 1.4 to 1.5wt%/day,
This is much higher than the general reduction rate of 0.5 to 1 wt%/day when burning without spraying water. For this reason, I was replenishing approximately 2.57 kg per hour. This seems to mean that many of the particles are crushed by thermal shock caused by water spray and sucked out of the system. According to the examples shown in the table above, the ratio between the amount of sprayed water and the amount of treatment was 0.8 or more, and in this case, the chlorine gas concentration could be suppressed to 10 ppm or less. but,
As shown in Comparative Example 1, when the ratio becomes 0.6, the chlorine gas concentration sharply increases to exceed 200 ppm even though the temperature is about the same. Conversely, when the ratio becomes 1.6 (Comparative Example 2), the hearth temperature becomes significantly lower than the hearth temperature, and the chlorine gas concentration becomes unstable. Therefore, in order to carry out combustion while stably suppressing the chlorine gas concentration to 10 ppm or less, the ratio of the amount of spray water to the amount of treatment should be set to 0.8 or more. However, if the ratio exceeds 1.6, the heat balance will be lost, so it should be kept at around 1.5. In addition, a large amount of fine sand powder with low melting point compounds attached was recovered by the cyclone. This means that when water spraying is performed, although approximately three times as much pulverized sand is scattered out of the system as when water is not sprayed, the average Na concentration in the collected ashes remains at 1.12 to 2.29wt%. It is clear from this. Also, SiO ₂ 84.02%,
When burning sand containing 1.67% Na ₂ O, 3.66% K ₂ O, and others, the Na concentration in the ash reached 6.7 to 10.4 wt% with or without water spraying. This resulted in adhesion to the furnace wall and flow inhibition, which is thought to be due to the high concentration of alkali salt. Therefore, it is desirable that the particles used be highly pure and inert. In short, the present invention uses a fluidized bed combustion furnace as a combustion device, and by spraying water into the interior of the furnace, chlorine is generated without causing troubles caused by low melting point compounds normally contained in organic chlorides to be burned. It converts gas into HCl and burns liquid, slurry, or solid organic salt compounds at low temperatures while suppressing chlorine gas, and its practical effects are extremely large.

[Brief explanation of the drawing]

The drawing is a vertical sectional side view of an example of a fluidized bed combustion furnace in which the present invention can be carried out, and FIG. 2 shows the same water spray nozzle as above.
FIG. 3 is a plan view showing the arrangement of the organic chloride supply device, and FIG. 3 is an enlarged longitudinal sectional side view of the nozzle.
denotes a fluidized bed, 8a...c a nozzle, and 9 a solid organic chloride supply device.

Claims (1)

[Claims] 1. When burning organic chlorides in a combustion furnace, water or an aqueous solution is sprayed into the furnace to improve contact between the water or aqueous solution and the chlorine gas generated by combustion, In the organic chloride incineration method that converts chlorine gas into HCl and reduces the amount of chlorine gas in the exhaust gas, the combustion furnace is of a fluidized bed type, high-purity silica sand is used as the fluidized bed medium particles, and the space inside the furnace is filled with water or In addition to spraying an aqueous solution, water or an aqueous solution is also sprayed into the bed of the fluidized bed to promote the scattering effect of the media particles compared to a general fluidized bed, and the media particles are forcibly crushed and pulverized by thermal shock. A low melting point compound contained in an organic compound is attached to the organic compound and scattered out of the system, and an amount of medium particles sufficient to compensate for the reduction in scattering is supplied to enable continuous operation.At the same time, the organic chloride becomes solid.
750℃ regardless of slurry, liquid, co-firing, or single-firing
A method for incinerating organic chlorides, which is characterized by converting chlorine gas into HCl at a relatively low temperature of ~1050°C. 2. The method for incinerating organic chlorides according to claim 1, wherein the ratio of water or aqueous solution to be sprayed to the amount of organic chloride to be treated is 0.8 to 1.5.