JPH0894056A - Incinerating method for organic waste - Google Patents

Abstract

PURPOSE: To suppress the generation of a detrimental substance such as dioxine, etc., and pretreat incinerated ash adaptively to be used as intimate mixture for cement to be incinerated by demineralizing organic waste before incinerating in the case of incinerating the waste, and hence reducing the damage of an incinerating furnace due to corrosion. CONSTITUTION: Organic waste is dry distilled by a dry distillation furnace 12 in a range of 150-1000 deg.C, or preferably 250-800 deg.C or more preferably 400-70 deg.C, obtained carbide is cooled, washing liquid is added to the carbide, cleaned, demineralized, then dehydrated by a solid-liquid separator 24, and then the demineralized carbide is incinerated by an incinerating furnace 26. Obtained ash which contains extremely small salt content, and extremely large silica contains the preferable contents as intimate mixture for cement.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for incinerating organic waste such as food waste, agricultural and marine waste, sludge, pulp sludge, waste wood, garbage waste, and the residue left after the waste is incinerated. The present invention relates to a method for incinerating organic waste by using incinerated ash as an admixture for cement.

[0002]

2. Description of the Related Art Conventionally, a part of the above organic waste is reused as feed or fertilizer, but most of it is incinerated as it is. At that time, since the organic waste generally contains a large amount of water, it was dried before incineration in many cases. In recent years, the following has been proposed as a method for incinerating organic waste or a method for treating incinerated ash. (1) A method of incinerating organic waste such as beer lees using a fluidized bed furnace (for example, Japanese Patent Laid-Open No. 2-97804,
JP-A-2-275203, JP-A-3-19980
No. 9 and Japanese Patent Laid-Open No. 4-214111). (2) A method for producing beer charcoal by pressing beer lees and subjecting it to thermal decomposition in a carbonization tank (dry distillation furnace) (see, for example, Japanese Patent Laid-Open No. HEI 2).
-294394). (3) A method in which 5 to 60 wt% of ash produced by burning and converting beer lees is used as a glaze for ceramics (see, for example, JP-A-4-50138). (4) A method of incinerating garbage and using the incinerated ash as a cement solidifying material (for example, Nikkei Business June 2, 1994).
No. 0, pp. 63-64).

[0003]

In the above-mentioned conventional method, the incinerator is damaged by HCl contained in the exhaust gas,
Further, since the exhaust gas contains harmful substances such as NOx and dioxin, and the incinerated ash contains salts, it cannot be reused and must be disposed of. As in the method of (4) above, cement that uses waste incineration ash is not corroded by salt, so it is highly corrosive and is used only as a cement raw material that does not use rebar. Limited and difficult to use in large quantities. In addition, the quality of waste itself is usually not constant, and a good admixture for cement that maintains a certain quality component from waste incineration ash cannot be obtained by conventional techniques.

However, under the present circumstances, for example, the reuse of beer lees for feed etc. is actively performed. But,
Feeds made from beer lees are not only nutritionally inferior compared to cheap and high-quality grain feeds, but they also have the drawback that they are highly susceptible to spoilage, so there are restrictions on distribution to the end user, the farmer, In particular, beer factories in the suburbs of cities are far from farmers, so most of the beer lees are incinerated in the factory, and only part of the energy obtained by incineration is recovered.

Generally, most of the incinerated ash is treated as industrial waste at the final disposal site, but especially in recent years,
Since there is no room for the final disposal site, the treatment of solid waste is becoming a huge social problem. Further, as described above, although attempts have been made to use the refuse incineration ash as a cement solidifying material, the quality of the waste itself is not stable in the first place, so the treatment of the waste incineration ash is mainly due to the melting of the ash. There was a problem that there was no way to recycle a large amount because it was limited to brick manufacturing. Further, when incinerating these wastes to recover energy, as described above, since the desalting step is not included in the usual method, the wastes are incinerated while containing salt. Therefore, when used as a concrete admixture, there was a problem that salt content had to be removed.

Further, in recent years, it has been known that, particularly in refuse incineration, when incinerated while containing salt, dioxin and the like which are highly toxic and have a large carcinogenic effect are generated (Resource Environment Countermeasures Vol. 30 No. 30). 7 (1994) p
It is introduced in 631 that waste incineration facilities occupy a large part due to the contribution of dioxin sources). We are dealing with a special combustion method that reduces the generation of dioxin by adjusting the combustion temperature after incineration, and there are many problems such as having to install a large-scale device to remove the generated dioxin. Was there.

The present invention has been made to solve the above-mentioned various problems, and its purpose is to reduce damage to an incinerator due to corrosion by desalting the organic waste before incineration. Another object of the present invention is to provide an incineration treatment method for organic waste, which suppresses the generation of harmful substances such as dioxins. Another object of the present invention is to provide a method of pretreating desalted incineration ash of organic waste so as to be suitable for use as an admixture for cement and incineration.

[0008]

In order to achieve the above object, the method for incineration of organic waste according to the present invention is such that the organic waste is subjected to dry distillation or heat treatment, and the obtained carbide is cooled. After that, a washing liquid is added to the charcoal-based material to wash the charcoal-based material for desalting, followed by dehydration, followed by incineration of the desalted charcoal-based material. The temperature of dry distillation or heat treatment is 150 to 100.
It is in the range of 0 ° C, preferably 250 to 800 ° C, and more preferably 400 to 700 ° C.

In the above method, it is preferable to dehydrate and dry the organic waste before the carbonization or the heat treatment.
Further, the incinerated ash of the demineralized carbide can be used as an admixture for cement. As the organic waste, at least one of food waste, agricultural and marine waste, sludge, pulp sludge, waste wood, and garbage waste is used. Among them, the food meal, beer meal, vinegar meal, coffee meal and sake meal, as the agricultural and marine waste, straw, rice husks, sugar cane squeezed lees, beet squeezed lees, citrus juice dregs,
Seagrass debris and fish debris are mentioned, and as garbage waste,
Household garbage, general garbage, kitchen waste and leftover food are included.

In the above method, a mineral acid such as sulfuric acid, hydrochloric acid or nitric acid or an organic acid such as formic acid or acetic acid is added to the washing solution, and the washing water is adjusted to have a weak acidity of pH 6 to 2, preferably pH 5 to 2. Preferably. In addition, an alkali such as sodium hydroxide, potassium hydroxide or calcium hydroxide is added to the washing solution, and the washing water is adjusted to pH 7.5 to 10, preferably pH 8
It is preferably weakly alkaline in the range of 10 to 10. Furthermore, it is preferable to add a metal chelating agent, which is a salt having a metal complex forming ability represented by EDTA, EDTP, NTA, etc., to the washing solution to make the washing water into a chelate aqueous solution.

As described above, according to the method of the present invention, in the step of incinerating the organic waste, the waste is 150 to 10
Perform dehydration / heat treatment or dry distillation once in the range of 00 ° C,
After cooling, water is added, and the main feature is to desalinate and dehydrate the carbide by washing with water, and then incinerate the desalted carbide.By adopting this method, compared with the conventional methods , It became possible to easily desalt. The discharged food by-products, agricultural and marine products by-products, sludge, pulp sludge and the like usually have a very high water content of 70 to 80% or more, and therefore are usually dehydrated and dried before the treatment step. In this case, the water content is preferably as low as possible, but it is preferably dehydrated and dried to 50% or less. After dehydration / drying, heat treatment or dry distillation is performed to improve desalination and solid-liquid separation of the organic waste. The treated waste is then cooled. In this case, the cooling temperature is preferably low, but 100 ° C. or lower is desirable.

Then, water is added to the cooled and heat-treated waste to agitate it for desalination. At this time, in order to remove previously undesired components from the component design of the finally obtained admixture for cement, add a small amount of acid or alkali.
It is also possible to prepare a liquid for washing with adjusted pH and use this as the liquid for washing. The desalination time and temperature should be adjusted according to the target organic waste, but usually 10
Stir at 0 ° C or less for several hours, preferably 30 to 90 minutes
Wash with water to desalt.

After the desalting operation is completed, it is then subjected to solid-liquid separation. In this case, since the waste has already been heat-treated, this solid-liquid separation operation becomes very simple. An ordinary mass-processing type centrifugal separator may be used, or filtration using a membrane or cloth having a knitting structure such as a screen or nylon gauze may be used. After the water is sufficiently drained and dehydrated, the waste becomes desalted waste, and after that, the waste may be subjected to a normal incineration process.

When the organic waste is incinerated in this way, not only does the ash after incineration contain no salt but a good admixture for cement is obtained, but the exhaust gas from incineration contains almost no hydrogen chloride. There is no need to worry about the generation of dioxins, and since the incinerator also has no salt content, damage to the incinerator is reduced, and as a result, the life of the incinerator is extended and the incineration cost is reduced. As described above, since the incinerated ash thus obtained by incineration does not contain salt, it can be effectively used as an admixture for cement.

FIG. 1 shows an example of a case of incinerating raw garbage. Raw garbage is first heated in a dryer 10 by hot air drying or the like to be dehydrated / dried, and then introduced into a carbonization furnace 12 (details will be described later) for carbonization. The dry distillation gas is condensed in the condenser 14 to obtain vinegar and tar, and the dry distillation residue (solid matter) is cooled in the cooler 16 and then the washing machine 18
After the mineral acid solution or the alkaline solution is added in, the solid-liquid separator 2
0 is introduced to separate the salt-containing wastewater. Solid-liquid separator 20
After the water is added to the solid substance from (1) by the stirring water washer 22 to wash it with stirring water, it is introduced into another solid-liquid separator 24 to separate salt-containing wastewater. The separated solid matter is incinerated in the incinerator 26 to obtain ash suitable as an admixture for cement.

FIG. 2 shows an example of incinerating beer lees. The beer lees are introduced into the carbonization furnace 12 (details will be described later) and carbonized. The carbonization gas is the condenser 14
The vinegar solution and tar are obtained by condensing in the above, and the dry distillation residue (solid matter) is cooled in the cooler 16, water is added in the washer 18, and then introduced into the centrifuge 30 to remove salt-containing substances. Wastewater is separated. Agitated water washer 2 for solids from centrifuge 30
After adding water in 2 and washing with stirring, the solid-liquid separator 24
Is introduced to separate the wastewater containing salt. The separated solid matter is incinerated in the incinerator 26 to obtain ash suitable as an admixture for cement.

FIG. 3 shows an example of the case of incinerating municipal waste. Municipal waste is introduced into the heat treatment machine 32 and subjected to heat treatment, cooled in the cooler 16 and then added with water in the washer 18, and then introduced into the solid-liquid separator 20 to separate salt-containing wastewater. To be done. The solid matter from the solid-liquid separator 20 is incinerated in the incinerator 26, and ash suitable for the admixture for cement is obtained.

FIG. 4 shows an example of a dry distillation furnace used in the method of the present invention. A case where beer lees are used as a raw material will be described as an example of organic waste. The raw material 56 is put into the dry distillation furnace 12, and after the lid 42 is closed and sealed, heating of the furnace is started by a heating body 44 such as a tubular electric furnace to heat the entire furnace to a predetermined temperature. After the raw material 56 is charged and the heater 44 is switched on, the stirrer 50 is started. The stirring speed at this time may be any speed as long as the raw materials can be uniformly mixed, but usually 50 rpm or less is preferable.

A heating temperature (temperature sensor) T3 arranged on the side of the carbonization furnace 12 detects the heating temperature, and this signal is input to a controller (not shown) of the heater 44 to reach a predetermined heating temperature. Is carried out while controlling the above. If the temperature sensing element T1 is installed in the central portion of the agitated raw material 56 and in the headspace inside the furnace for control so that excessive heating or insufficient heating does not occur, more accurate and reliable temperature control can be achieved. It will be possible. The temperature for dry distillation is 150 to 10
No matter what temperature is selected within the range of 00 ° C., it suffices to carry out dry distillation by controlling it so as to be constant. It is desirable to select and control the temperature in a range of 400 to 700 ° C. in which the yields of the dry distillation condensed aqueous solution (vinegar solution) and the oily solution (tar) are high.

Next, the dry distillation gas distilled out by heating is cooled using a condenser (indirect cooling pipe) 14 and captured as a condensate, and an vinegar solution and an oily solution (tar) are recovered. At this time, the cooling temperature may be higher than the solidification temperature of the oily liquid thus obtained and lower than the condensation temperature. Particularly, in the range of 30 to 60 ° C., the viscosity of the condensed liquid is low and the yields of vinegar and oily liquid are high. Next, carbonization furnace 1
Regarding the heating method of No. 2, it is preferable to raise the temperature to the predetermined dry distillation temperature promptly, but if the arrival time to the predetermined temperature is kept constant, vinegar solution of constant quality can be obtained.

The time for maintaining the dry distillation temperature after reaching the predetermined temperature may be determined while observing the distillation conditions of the vinegar solution and the oily solution, and is not particularly limited. Usually, the dry distillation operation is finished at the time when the distillation of the vinegar solution and the oily solution is completed, but the dry distillation may be stopped in the middle if the desired amount can be secured. 48 is a stirring motor, 52 is a heater, 54 is an inert gas supply pipe,
58 is a receiving container, 60 is dry distillation condensed water-soluble liquid (vinegar solution), 6
2 is an oily liquid (tar), and T2 and T4 are temperature measuring elements (temperature sensors). The tip of the inert gas supply pipe 54 may be inserted into the raw material or may be located at the bottom of the raw material.

[0022]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications can be made as appropriate. Example 1 As shown in FIG. 5, household garbage 500 g (water content 85
%) With hot air at 85 ° C. for 60 minutes and then 450
The mixture was subjected to dry distillation treatment at 30 ° C. for 30 minutes to obtain 20 ml of vinegar and 10 ml of tar, 45 g of a solid matter. The solid thus obtained was left to cool to 50 ° C. After adding 1000 ml of 0.2 N sulfuric acid solution to this solid, it was desalted by filtering through a filter paper. The amount of salt-containing wastewater was 950 ml. Further, 1000 ml of tap water was added to the filtered solid matter, and the mixture was stirred, washed thoroughly with water, and then subjected to simple filtration with a filter paper. The amount of salt-containing wastewater was 950 ml. By this filtration operation, the water content is 25%
42 g of desalted solid of was obtained. This desalted solid was put into a crucible and heated to 500 ° C. in the presence of air to obtain 7 g of ash. Analysis of the ash obtained by this method showed that the salt content was extremely low (0.01% or less) and the silica content was 89%.
% (W / V), which was a high-quality ash having a very preferable component as an admixture for cement.

The cement admixture thus obtained was 25 kg, ordinary Portland cement 95 kg, fine aggregate (sand from Kinokawa) 675 kg, coarse aggregate (crushed stone from Takarazuka) 150
Concrete was prepared by kneading 0 kg and 100 kg of water. As a result of testing the compressive strength of this concrete, 26
It was 7 kg / cm ² . On the other hand, without mixing the admixture for cement obtained as described above, 95 kg of ordinary Portland cement, 675 kg of fine aggregate (sand from Kinokawa), 1500 kg of coarse aggregate (crushed stone from Takarazuka) and 100 kg of water were kneaded. When concrete was prepared and the compressive strength of this concrete was tested, it was 254 kg / cm ² . From these, it is understood that when the incineration ash obtained by the method of the present invention is added as an admixture for cement, concrete having strength equal to or higher than that of conventional concrete can be obtained.

Example 2 As shown in FIG. 6, 2.5 kg of beer lees were heated at 450 ° C. for 60 hours.
The mixture was subjected to dry distillation for 1 minute to obtain a total of 987 ml of vinegar and tar and 657 g of a solid matter. The solid was left to cool to 90 ° C., 3 liters of tap water was added, then introduced into a centrifuge and centrifuged at 5000 rpm for 10 minutes. The amount of drainage containing salt was 2.5 liters. To the separated solid matter, 3 liters of tap water was added, washed with stirring water for 40 minutes, and then solid-liquid separated using a nylon gauze. The salt-containing wastewater was 2.5 liters. By this solid-liquid separation operation, 820 g of desalted solid matter having a water content of 25% was obtained. The desalted solid was placed in a crucible and heated to 750 ° C. in the presence of air to obtain 73.1 g of ash. As a result of analyzing this ash, the salt content is extremely low (0.01% or less), and the silica content is 84.3% (W / V).
As a result, it was a high quality ash having a very large amount of preferable components as an admixture for cement.

Example 3 As shown in FIG. 7, 1 kg of municipal waste was introduced into a stirring type heating and roasting machine and heat-treated at 250 ° C. for 60 minutes, and then the treated solid was air-cooled to 30 ° C. Then, 2 liters of tap water was added to 528 g of the solid matter, and solid-liquid separation was performed using nylon gauze. The salt-containing wastewater was 1.8 liters. By this solid-liquid separation operation, 719 g of a solid substance having a water content of 32% was obtained. This solid was put in a crucible and heated to 900 ° C. in the presence of air to obtain 89 g of ash. As a result of analysis of this ash, it was found that the ash had a very low salt content (0.02%) and was a good quality ash having a preferable component as an admixture for cement.

Example 4 1 kg of city garbage (65% water content) containing 24 ppm of lead (Pb) with respect to solid content was stirred with a stirring type heating and roasting machine.
After treatment at 0 ° C. for 80 minutes, the treated solid is air-cooled to 30
Cooled to ° C. Then, 2 l of a 2% acetic acid solution was added to 638 g of the solid matter, and the mixture was filtered through a nylon gauze to obtain 830 g of a solid matter having a water content of 24%. The drainage containing salt was 1.8 liters. 2 l of tap water was further added to this solid matter, and the solid matter was washed with water for 2 hours with occasional stirring. This was filtered with filter paper to obtain 770 g of a solid substance having a water content of 20%. The salt-containing wastewater was 1.85 l. Put this solid in a crucible,
When it was heated to 0 ° C in the presence of air and burned, ash was reduced to 6
3 g was obtained. As a result of analysis of this ash, lead (Pb), which was initially contained in the solid content of 24 ppm, was reduced to 3 ppm. Further, the salt content was also 0.01% or less, and the ash was a good quality having desirable components as an admixture for cement.

[0027]

Since the present invention is configured as described above, it has the following effects. (1) Since it is desalted before being incinerated, HCl or the like is not contained in the exhaust gas of the incinerator or only a trace amount of HCl or the like is contained, so that damage to the incinerator due to corrosion is reduced. (2) When dry-distilling before incineration, nitrogen compounds are decomposed and recovered as vinegar or tar, and since Cl ⁻ is reduced due to desalting, harmful substances such as NOx and dioxins are generated. Is extremely small. (3) By the above (2), a harmful substance removing step and a removing device are not required, and the cost can be reduced. (4) In the case of using not only water but also weak mineral acid water or weak alkaline water for desalting, the ash content obtained after incineration can be adjusted, and the ash can be effectively used. (5) By the above (4), trace components (Mg, S, P, Zn) that adversely affect the quality of concrete are selectively removed, and discharged ash is adjusted in advance to a component suitable for a cement admixture. be able to. (6) Heavy metals such as Cr, Hg, Pb, and V that are harmful to the human body can be selectively removed. (7) When burned ash is used as an admixture for cement, it is not necessary to dispose of the ash, and it is not necessary to secure the final disposal site.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an example of a method for incinerating organic waste according to the present invention.

FIG. 2 is a flow sheet showing another example of the method of the present invention.

FIG. 3 is a flow sheet showing still another example of the method of the present invention.

FIG. 4 is a schematic configuration diagram showing an example around a dry distillation furnace used in the method of the present invention.

5 is a flow sheet in Example 1. FIG.

6 is a flow sheet in Example 2. FIG.

7 is a flow sheet in Example 3. FIG.

[Explanation of symbols]

 10 Dryer 12 Dry Distillation Furnace 14 Condenser 16 Cooler 18 Washer 20 Solid-Liquid Separator 22 Stirring Water Washer 24 Solid-Liquid Separator 26 Incinerator 30 Centrifuge 32 Heat Treatment Machine 60 Vinegar 62 Oily liquid (tar)

Claims (10)

[Claims] 1. An organic waste is subjected to dry distillation or heat treatment, and the obtained charcoal is cooled, and then a washing liquid is added to the char to wash and desalt, followed by dehydration, followed by incineration of the desalted char. A method for incineration of organic waste, which comprises: 2. The method for incinerating organic waste according to claim 1, wherein the organic waste is dehydrated and dried before being subjected to carbonization or heat treatment. 3. The method for incinerating organic waste according to claim 1 or 2, wherein incinerated ash of demineralized carbide is used as an admixture for cement. 4. The organic waste according to claim 1, 2 or 3, wherein the organic waste is at least one of food waste, agricultural and marine waste, sludge, pulp sludge, waste wood and garbage waste. Incineration treatment method of system waste. 5. The method for incinerating organic waste according to claim 4, wherein the food waste is beer meal, vinegar meal, coffee meal and sake meal. 6. The method for incineration treatment of organic waste according to claim 4, wherein the agricultural and marine product waste is straw, rice husk, sugar cane squeezed lees, beet squeezed lees, citrus juice dregs, seaweed debris and fish debris. 7. The method of incineration of organic waste according to claim 4, wherein the garbage waste is household garbage, general garbage, kitchen waste and leftover food. 8. An acid is added to the washing liquid, and the washing water is adjusted to pH 6 to 6
The method for incineration of organic waste according to any one of claims 1 to 7, wherein the acidity is weakly acidic within the range of 2. 9. An alkali is added to the washing liquid, and the washing water is added.
A weakly alkaline pH range of 7.5 to 10.
7. The method for incineration of organic waste according to any one of 7. 10. The method for incineration of organic waste according to claim 1, wherein a metal chelating agent is added to the washing liquid and the washing water is an aqueous chelate solution.