JP2001208325A - Treatment method of dehydration sludge and manufacturing method of spherical powder slag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of spherical powder slag that can efficiently dry dehydration sludge in a dryer, can miniaturize the grinder of the dry sludge, and can save energy when the spherical powder slag is to be manufactured from the dry sludge. SOLUTION: In this manufacturing method of spherical powder slag that dries dehydration sludge S by a dryer 1, dry sludge being adjusted to a specific moisture content by the dryer 1 is ground so that the dry sludge has a specific grain size for supplying to a burner Br being provided in a spheroidizing furnace T, and is jetted out with one part of air for combustion from the burner for manufacturing the spherical powder slag. In the manufacturing method, inorganic matters in the dry sludge are fused by the combustion heat being generated by the combustion of organic matters in the dry sludge while the inorganic matters are in a floating state. Further the fused object is cooled in the furnace in a floated state as the spherical powder slag, and at the same time one part of the spherical powder slag is supplied to the dryer at high temperature for mixing with the dehydration sludge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for treating dewatered sludge and a method for producing spherical powder slag.

[0002]

2. Description of the Related Art Conventionally, as a method of treating dehydrated sludge, dehydrated sludge is incinerated in an incinerator, and the sludge incineration ash is spray-supplied into a spheroidizing furnace through a burner to melt the incineration ash with a burner flame. (Japanese Patent Laid-Open Publication No. 10-169951) and a method of spraying and supplying a dried dewatered sludge (dry sludge) to a spheroidizing furnace through a burner to form a spherical powder slag. A method of using slag (Japanese Patent Laid-Open No. 11-37439) has been conventionally proposed.

[0003] Among the spherical powder slags produced by the above method, those having an average particle diameter of 20 to 30 µm (80 to 85 wt% of the entire spherical powder slag produced) have a mean particle size of fluidized concrete or the like. Those having a size of 3 to 5 μm (15 to 20 wt% of the entire spherical powder slag produced) are used as fillers for paints and the like and are recycled.

Since the sludge incineration ash contains only inorganic substances such as SiO ₂ , in the former method, all the heat required for melting the sludge incineration ash is obtained by burning separately supplied fuel by a burner. They had to make up for it, so they had to use more fuel. Therefore, recently, when producing spherical powdered slag, incineration ash is not used, and the latter method, that is, dry sludge is supplied to a burner, and the organic matter in the dried sludge is effectively used as fuel to save energy. Like that.

[0005] In this case, if the dewatered sludge having a water content of 75 to 80 wt% is melted as it is, a large amount of heat is required to evaporate the water and a separate fuel must be supplied. The heat of the discharged exhaust gas is recovered, and the recovered heat is supplied to a drier to be dried so that the water content becomes 30 wt% or less. I have. At this time, in order to reduce the load on the dryer, a means for reducing the apparent moisture content of the dewatered sludge by mixing sludge incineration ash as a drying aid with the dewatered sludge is employed.

In order to supply the powdery dry sludge to the burner, a pulverizer is provided downstream of the dryer.

[0007]

However, the incinerated ash has a polygonal shape when viewed microscopically, so it is difficult to mix uniformly with dehydrated sludge having poor fluidity and high tackiness, and the incinerated ash is difficult to mix. Since the particles have many micropores and cracks, they absorb the moisture in the dewatered sludge and adhere to the dewatered sludge to form agglomerates, which reduces the contact area between the high-temperature atmosphere and the dewatered sludge in the dryer. However, there is a problem that the drying efficiency does not increase.

Further, since the agglomerated dewatered sludge becomes a dried sludge as a lump, it must be finely divided (0.5 mm or less) so that it can be sprayed from a burner, and the burden on the pulverizer increases. there were.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for treating dewatered sludge, wherein the dewatered sludge is dried by a drier and adjusted to a predetermined moisture content.
The dewatered sludge is mixed with a spherical powder slag having good fluidity and not absorbing water in the dewatered sludge.

The spherical powder slag is obtained by drying dewatered sludge with a drier, pulverizing the dried sludge adjusted to a predetermined moisture content to a predetermined particle size by the drier, and then disposing the burner in a sphering treatment furnace. And producing a spherical powder slag by blowing out from the burner together with a part of the combustion air. While melting the inorganic components in a floating state, the melt is cooled in a furnace in a floating state to form spherical powder slag, and a part of the spherical powder slag is supplied to the dryer, and the dewatered sludge is supplied. And to be mixed.

In this case, a high-temperature collecting means for the spherical powder slag is provided downstream of the spheroidizing furnace, and the spherical powder slag collected by the high-temperature collecting means is supplied to the dryer and mixed with the dewatered sludge. Is preferred.

Preferably, the mixing amount of the spherical powder slag is 1 to 10% by weight of the dewatered sludge treatment amount.

[0013]

Next, an embodiment of the present invention will be described with reference to the processing flow shown in FIG. The dewatered sludge S having a water content of 75 to 80 wt% is supplied to the dryer 1 and dried to be dried sludge having a water content of 30 wt% or less.

In this case, the heat of the exhaust gas discharged from the spheroidizing furnace T described below is primarily recovered by the air preheater 9 and used as combustion air in the spheroidizing furnace T. The waste heat boiler 10 disposed downstream of the vessel 9 secondarily collects the heat of the exhaust gas to generate high-temperature steam, and supplies the high-temperature steam to the dryer 1 to dry the dewatered sludge.

Then, the dried sludge is pulverized by
After being pulverized to a size equal to or less than mm, it is supplied to the hopper 3, from which it is supplied to the sphering furnace T by the pneumatic transport device 4 via the pipe P.

As shown in FIG. 2, the spheroidizing processing furnace T has a stepwise increasing cross-sectional area in the furnace, and a purge air nozzle 13 is provided at each step 12 of the furnace inner wall. Tens of nozzles are attached in the direction, and purge air is ejected from a downwardly opening ejection hole 13a formed at the tip of the purge air nozzle 13 to lower the temperature of the furnace wall, thereby adhering the clinker to the furnace wall. Has been prevented.

A burner Br and an auxiliary burner Br 'are attached to the ceiling of the spheroidizing furnace T. The burner Br is a double pipe as shown in FIG. 3, and a gas supply passage formed between an inner pipe 14 communicating with the pipe P and an outer pipe 15 provided at a predetermined interval from the inner pipe 14. 16.

A portion of the pulverized dry sludge and a portion of the combustion gas such as air or oxygen-enriched air is supplied from the inner tube 14, and a portion of the combustion gas such as air or oxygen-enriched air is supplied from the gas supply passage 16. Supply gas for each. Reference numeral 17 denotes a turning blade.

The auxiliary burner Br 'is a known burner using kerosene or the like as a fuel, and is attached so as to be inclined such that a flame formed by burning the fuel intersects the axis of the burner Br.

When the spheroidizing furnace T is started up, the inside of the furnace is first heated to a predetermined temperature (for example, 700 ° C. at which dry sludge can self-combust) by burning the auxiliary burner Br ′. Dry sludge and combustion air are supplied from the burner Br to start spheroidization. At this time, since the auxiliary burner Br 'is attached at an angle as described above, the flame from the auxiliary burner Br' and the dry sludge surely come into contact with each other, thereby preventing the generation of unburned components. Further, when the furnace temperature rises to a temperature at which the dried sludge stably burns (for example, 800 ° C.), the auxiliary burner Br ′ is extinguished and a steady operation is performed.

During the steady operation of the spheroidizing furnace T, in the high-temperature combustion flame formed by the organic gas and the combustion gas of the dry sludge supplied from the inner pipe 14 and the gas supply path 16 of the burner Br, The inorganic component in the dried sludge is heated, and the flat inorganic component particles are melted in a floating state and are spheroidized by surface tension. The spheroidized molten particles are eventually discharged out of the combustion flame and solidified into a spherical powder slag by being rapidly cooled in a floating state in a furnace maintained at a melting temperature or lower, and the slag is subjected to hot cyclone along with the exhaust gas. 5 in which spherical powder slag having an average particle diameter of 20 to 30 μm (80 to 8 of the entire spherical powder slag produced) was used.
5 wt%) is taken out and stored in the hopper 6.

The exhaust gas discharged from the hot cyclone 5 reaches the ceramic filter chamber 7 where the average particle size is 3.
Spherical powder slag of ５5 μm (15 to 20 wt% of the entire manufactured spherical powder slag) is taken out and stored in the hopper 8.

Exhaust gas from which spherical powder slag having a small particle diameter has been removed in the ceramic filter chamber 7 (700 ° C. or higher)
As described above, the heat passes through the air preheater 9 and primarily recovers the heat of the exhaust gas, and is used as combustion air in the spheroidizing furnace T.

Further, since the exhaust gas leaving the air preheater 9 still retains heat, high temperature steam is generated in the waste heat boiler 10 and used as a drying heat source for the dryer 1. on the other hand,
The cooled exhaust gas is discharged to the atmosphere from a chimney (not shown) through a flue gas treatment tower 11.

By the way, the spherical powder slag collected by the hot cyclone 5 and the filter of the ceramic filter chamber 7 is taken out from the hoppers 6 and 8, respectively, and is used as a fluidized material of concrete or a filler for paint. With
Part of each of the spherical powder slags is supplied to the dryer 1 as a drying aid. In this case, the amount of the spherical powder slag supplied to the dryer 1 is supplied in the range of 1 to 10% by weight of the dewatered sludge, and is mixed with the dewatered sludge to reduce the apparent water content of the dewatered sludge. (Drying efficiency).

The reason why the mixing amount of the spherical powder slag is limited to the range of 1 to 10 wt% with respect to the treatment amount of the dewatered sludge is that if the mixing ratio is less than 1 wt%, the apparent water content hardly changes. If the content is more than 10 wt%, the ratio of the inorganic component in the dehydrated sludge to the total (total inorganic component) of the separately supplied spherical powder slag and the inorganic component (source of the spherical powder slag) contained in the dehydrated sludge is half. This is because the production efficiency of the spherical powder slag deteriorates as follows.

The spherical powder slag has a very good fluidity because the particles of the dewatered sludge (dry sludge) are spheroidized by melting, and is mixed with the dewatered sludge having a high water content because the surface is vitrified. Even though the dewatered sludge is not adsorbed, the dewatered sludge does not clump around the spherical powder slag.

That is, since the dewatered sludge is not adsorbed, microscopically, a fine space is formed around the spherical powder slag, and the contact area of the dryer 1 with the high-temperature atmosphere is increased, and the drying efficiency is increased. Is improved.

[0029] In addition, because of the spherical shape, the fluidity is high, so that it can be uniformly mixed with the dewatered sludge, and the agglomeration of the dewatered sludge can be more effectively prevented.

Further, as described above, the water content is 30 wt%.
The following dried sludge is pulverized to 0.5 mm or less by the pulverizer 2, but also in this case, the load on the pulverizer 2 can be reduced because the dried sludge does not form a lump.

The burner Br in the spheroidizing furnace T
Uses the auxiliary burner Br 'at the time of startup, but does not use it during the steady state (does not use fuel) and burns using the organic component contained in the dry sludge as fuel (the lower heating value of the dry sludge is 3200 kcal / kg or more) So the flame temperature is 14
00 ° C or higher).

A burner Br provided in the spheroidizing furnace T
It is not necessary to limit the number to one, and two or more may be used. When a plurality of burners are provided, a distributor is provided upstream of the burners so that the dry sludge is evenly supplied to each burner.

Further, in the spheroidizing furnace T, a large-diameter spherical powder slag outlet (not shown) is provided at the bottom.
The spherical powder slag may be supplied to the dryer 1 or used effectively. In any case, by collecting the spherical powder slag at a high temperature (700 ° C. or higher) and returning it directly to the dryer 1, the heat held by the collected spherical powder slag can be used for drying, further improving the drying efficiency. I do.

Further, arsenic,
Although heavy metals such as selenium may be contained, since these heavy metals evaporate in a high temperature range of 700 to 800 ° C., each of the spherical powder slags is collected in a state separated from heavy metal vapor, and the spherical powder slag is collected. No heavy metal adheres to the surface of the slag, and a safe spherical powder slag without danger of elution of the heavy metal can be obtained.

[0035]

As is apparent from the above description, claim 1
According to the invention, in a method for treating dewatered sludge, in which the dewatered sludge is dried by a dryer and adjusted to a predetermined moisture content, a spherical powder slag having good fluidity and no water absorption is used as a drying aid for the dewatered sludge. To mix dewatered sludge uniformly, the porosity of the dewatered sludge is improved, and the agglomeration of the dewatered sludge can be prevented, and the contact area with the high-temperature atmosphere in the dryer increases. The heat supply efficiency can be improved, and the drying efficiency in the dryer can be improved.

According to the second aspect of the present invention, dry sludge pulverized to a predetermined particle size is supplied to a burner together with combustion air, and a separate fuel is supplied to use organic matter in the dry sludge as fuel. It is not necessary, and a part of the spherical powder slag generated there is supplied to a drier and used as a drying aid for dewatered sludge. As described above, the agglomeration of the dewatered sludge can be prevented by the mixing, and the burden on the crusher is reduced.
The size of the crusher can be reduced.

Further, by using the spherical powder slag collected by the high-temperature collecting means provided downstream of the spheroidizing furnace as the drying aid, the heat retained in the slag is also used as a heat source in the dryer. As a result, the drying efficiency in the dryer can be improved.

By limiting the mixing amount of the spherical powder slag to the dewatered sludge, it is possible to prevent a reduction in the processing efficiency of the dewatered sludge.

[Brief description of the drawings]

FIG. 1 is a process flow showing a process for treating dewatered sludge and a method for producing a spherical powder slag according to the present invention.

2A is a sectional view of a spheroidizing furnace, and FIG. 2B is an enlarged sectional view of a main part of FIG. 2A.

FIG. 3 is a sectional view of the burner of FIG. 2;

[Explanation of symbols]

1-dryer, 2 crusher, 5 hot cyclone, 7-
Ceramic filter, Br-burner, T-spheroidizing furnace.

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Claims (4)

[Claims] 1. A method for treating dewatered sludge, wherein the dewatered sludge is dried by a dryer and adjusted to a predetermined moisture content, wherein a spherical powder slag is mixed with the dewatered sludge. 2. The dewatered sludge is dried by a dryer, the dried sludge adjusted to a predetermined moisture content by the dryer is crushed to a predetermined particle size, and then supplied to a burner provided in a spheroidizing treatment furnace. In the method for producing a spherical powder slag to produce a spherical powder slag by squirting together with a part of the combustion air from,
While the inorganic components in the dried sludge are melted in a floating state by the heat of combustion due to the combustion of the organic components in the dried sludge, the molten material is cooled in a furnace in a floating state to form a spherical powder slag. A method for producing a spherical powder slag, wherein a part of the spherical powder slag is supplied to the dryer and mixed with the dewatered sludge. 3. A high-temperature collecting means for the spherical powder slag is provided downstream of the spheroidizing furnace, and the spherical powder slag collected by the high-temperature collecting means is supplied to the dryer and mixed with the dewatered sludge. The method for producing a spherical powder slag according to claim 2, wherein: 4. The method for treating dewatered sludge according to claim 1, wherein the mixing amount of the spherical powder slag is 1 to 10% by weight of the dewatered sludge treatment amount.