JP4445148B2 - Sludge treatment method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for treating sludge such as sewage sludge and industrial waste sludge, and more specifically, as a pretreatment for introducing sludge into a cement rotary kiln, the sludge is efficiently dried to facilitate handling. The present invention relates to a method and apparatus for treating sludge that has a process, has a small amount of bleed gas, suppresses an increase in heat consumption of cement firing, stabilizes the quality of cement clinker, and allows a large amount of sludge to be introduced into a rotary kiln. is there.
[0002]
[Prior art]
Most of the sludge such as sewage sludge and industrial waste sludge has been dehydrated and dried and then disposed of by incineration of organic matter in the sludge in a fluidized bed furnace or rotary kiln. However, by incineration with a rotary kiln, the combustion heat of sludge is effectively used and incineration ash is recovered as part of the cement raw material.
[0003]
Conventionally, as a sludge treatment technology, for example, in Japanese Patent Laid-Open No. 9-248600, sewage sludge is dehydrated and dried, and the dried sludge is mixed and aged with quick lime to obtain a dried powder. A method of mixing and pulverizing with a raw material and using it as a raw material and fuel for cement production is disclosed.
[0004]
JP-A-8-276199 discloses a sludge treatment method in which water-containing sludge is directly introduced into a kiln bottom or calciner of a dry kiln for producing cement clinker and incinerated.
[0005]
Japanese Patent Laid-Open No. 11-116290 discloses a method for producing cement in which sludge containing an odorous compound is supplied to a drying process or pulverization process of a cement raw material, dried or pulverized, and then supplied to a firing process. ing. And this gazette describes the experimental result which can deodorize, when the sludge containing an odorous compound is made to contact with a cement raw material.
[0006]
[Problems to be solved by the invention]
The method of using sewage sludge as a raw material for cement production and fuel described in JP-A-9-248600 has the following problems.
(1) Heat loss is large because quick lime that requires a large amount of calorie is used in large quantities.
(2) It is necessary to treat steam, dust and odor generated when mixing sludge and quicklime.
(3) It is necessary to deodorize the exhaust gas from the sludge dryer.
(4) Exhaust gas treatment facilities and wastewater treatment facilities will be large.
[0007]
The sludge treatment method described in JP-A-8-276199 has the following problems.
(1) The amount of heat required to evaporate sludge moisture is large, the firing temperature is rapidly lowered, and the heat consumption for cement firing is deteriorated.
(2) The amount of cement preheater exhaust gas increases due to the evaporation of moisture, resulting in a decrease in cement clinker production.
(3) For the above reasons, the amount of sludge treatment cannot be increased too much.
(4) The cement firing temperature becomes unstable due to fluctuations in sludge moisture and sludge supply.
(5) Since the water-containing sludge thrown into the kiln becomes a lump, mixing with the cement raw material is poor, and the cement quality becomes unstable.
(6) The sludge pressure-feeding pipe is easily clogged, and the cleaning work is complicated. During this time, sludge cannot be introduced.
(7) It is necessary to treat the odor generated when receiving sludge.
[0008]
Further, the cement manufacturing method described in JP-A-11-116290 has the following problems.
(1) Although it is recognized that the cement raw material has a certain degree of deodorizing action, even if sludge is brought into contact with the cement raw material, it cannot be completely deodorized.
(2) In actual operation, further deodorization treatment is required, such as thermal decomposition of the odor component in the dryer exhaust gas to 600 ° C. or higher or treatment with an activated carbon adsorption tower.
(3) Treatment of odor generated during sludge acceptance and sludge transportation is necessary.
It is also known to deodorize by blowing odor gas into high-temperature parts such as calcining furnaces, kilns, coolers, etc., but the increase in the amount of exhaust gas for cement production and the amount of heat for firing is great, and the amount of sludge treatment is reduced. I can't do much.
[0009]
The present invention has been made in view of the above points, and an object of the present invention is to combine an air flow dryer and a cement baking apparatus, to provide an exhaust gas heating unit at a high temperature portion of the cement baking apparatus, Providing heat treatment equipment that preheats, providing a sludge treatment method and apparatus that can throw in a large amount of sludge without deteriorating the heat consumption of cement baking equipment as much as possible, and that can be released into the atmosphere by deodorizing the exhaust gas from the air dryer. There is to do. Furthermore, the object of the present invention is to supply a part of the exhaust gas from the air dryer heated and deodorized in the high temperature part of the cement baking apparatus to the pulverizer as a heat source of the air dryer, so that the amount of exhaust gas from the dryer and bleed gas can be obtained. An object of the present invention is to provide a method and apparatus for treating sludge that reduces the amount of the apparatus and makes the apparatus smaller.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the sludge treatment method of the present invention adjusts moisture by mixing and stirring the sludge circulating dry powder that has been air-dried to the sludge cake from the sludge cake tank, and then mixing the mixed powder. After being crushed with an air dryer crusher, it is dried in a drying duct and collected with a dust collector to obtain dry powder, and a certain amount of this dry powder is blown into a rotary kiln and / or calcining furnace. A method for obtaining cement clinker by using it as a part of a cement clinker firing fuel and cooling the fired product together with the cement raw material fired product, and heating the exhaust gas of the dryer at the high temperature part of the cement firing device indirectly The flue gas dryer exhaust gas is introduced into the flue gas heating section, heated and deodorized, and a part of the heated and deodorized gas flow dryer exhaust gas is circulated to the crusher of the gas dryer to increase the gas content (evaporated moisture). And leak ) Is bleed out of the system, heat exchange is performed between the remainder of the heated and deodorized air dryer exhaust gas and the air dryer exhaust gas from the air dryer dust collector. It is configured to preheat the air dryer exhaust gas (see FIGS. 1 and 2).
[0011]
In the above method, the preheated air-flow dryer exhaust gas is heated and deodorized to 600 ° C. or more in the exhaust gas heating section (see FIG. 2). By setting the temperature to 600 ° C. or higher, the odor component in the exhaust gas burns or decomposes to be deodorized.
Moreover, the circulation amount of the dry powder mixed with the sludge cake is adjusted so that the water content of the mixed powder is 30% or less. By making the water content of the mixed powder 30% or less, the powder becomes weakly adherent, and adhesion troubles in the apparatus are prevented.
[0012]
In these methods, it is preferable that the odor generated when the sludge cake is received in the sludge cake tank is the rotary kiln of the cement baking apparatus and / or the combustion air of the calciner (see FIG. 1).
[0013]
The sludge treatment apparatus of the present invention includes a mixing unit that mixes a sludge cake and a part of dry powder dried by an air dryer described below, and a crusher that crushes the mixed powder from the mixing unit together with a hot air flow. A substantially vertical drying duct for air-drying the crushed powder, a dust collector connected to the upper end of the drying duct, a dryer exhaust gas duct connected to the upper portion of the dust collector, An air dryer having a dry powder supply tank attached to a lower part of the dust collector via a discharger, a suspension preheater composed of a plurality of cyclones, and a cyclone at the lowest stage of the suspension preheater A rotary kiln connected to the calcining furnace and the lowermost cyclone via an inlet hood, and a cooler connected to the outlet of the rotary kiln. A dry powder supply device of the air dryer is connected to an inlet hood or / and a calciner of the rotary kiln via a quantitative supply device and a dry powder air transport device. The dry exhaust gas duct of the dryer is connected to the exhaust gas heater at the high temperature part of the cement firing device via an indirect heat exchanger, and the heating / deodorizing exhaust gas duct at the outlet of this exhaust gas heater is branched, one branch The duct is connected to the crusher, and the other branch duct is connected to the indirect heat exchanger so that a part of the heated / deodorized exhaust gas is circulated to the crusher (Fig. 1).
[0014]
In this apparatus, the exhaust gas heater is preferably a jacket structure (see FIG. 2).
It is preferable that the high temperature part of the cement baking apparatus is at least one of a suspension preheater, an inlet hood, a rotary kiln, and a cooler.
[0015]
In these apparatuses, a cyclone or a bag filter is used as the dust collector. When a cyclone is used, a cylindrical portion having a linden-type inlet duct, a substantially inverted truncated cone-shaped upper cone connected to the lower end of the cylindrical portion, and a lower end of the upper cone are inserted below the upper cone. The lower cone of the upper cone is composed of a substantially inverted conical lower cone having a discharge port in the lower part and an inner cylinder inserted from above so that the upper end protrudes as an outlet part at the center of the cylindrical part. It is preferable to use a cyclone having an inner diameter D1 of 0.9 to 1.1 times the inner diameter d of the inner cylinder, that is, D1 = 0.9 to 1.1d (see FIG. 3). In this case, the top wall of the lower cone is preferably configured to be substantially horizontal.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.
FIG. 1 shows a sludge treatment apparatus according to a first embodiment of the present invention. A dewatered cake of sludge such as sewage sludge and industrial waste sludge is transported by the vehicle 10 or the like and stored in the sludge cake tank 14 in the sludge cake receiving chamber 12. 16 is a sludge cake discharger, 18 is an odor fan.
[0017]
The sludge cake in the sludge cake tank 14 is discharged by the sludge cake discharger 16 and supplied to the mixing unit 22 of the airflow dryer 20 and mixed with the circulating dry powder.
The air dryer 20 includes the mixing unit 22 that mixes the sludge cake and a part of the air-dried dry powder, the crusher 24 that crushes the mixed powder from the mixing unit 22 together with the hot air flow, A substantially vertical drying duct 26 for air-drying the pulverized powder, a dust collector connected to the upper end of the drying duct 26, for example, a dry powder cyclone 28, and a drying connected to the upper part of the cyclone 28. It has a machine exhaust gas duct 30 and a dry powder supply device 34 in a dry supply tank 39 connected to the lower part of the cyclone 28 via a discharger 32. A circulating dry powder feeder 36 for circulating a part of the dry powder is provided below the dry powder feeder 34, and a sludge cake charging port 38 is connected to the circulating dry powder feeder 36 to form the mixing unit 22. ing. The dry powder supply tank 39 includes a dry powder supply device 34 and a circulating dry powder supply machine 36.
[0018]
On the other hand, the cement baking apparatus 40 includes a suspension preheater 42 composed of a plurality of stages, for example, four stages of cyclones C1, C2, C3, and C4, and a calcining furnace 44 connected to the lowermost cyclone C1 of the suspension preheater 42; A rotary kiln 48 connected to the calcining furnace 44 and the lowermost cyclone C1 via an inlet hood 46 and a cooler 50 connected to an outlet portion of the rotary kiln 48 are provided. 52 is a cement raw material inlet, 54 is a calciner burner, and 56 is a kiln burner.
[0019]
The dry powder supply device 34 of the air dryer 20 is connected to the inlet hood 46 of the rotary kiln 48, before the kiln or / and the calcining furnace 44 via the fixed amount supply device 58 and the dry powder air transport device 60.
Further, the dry exhaust gas duct 30 of the air dryer 20 is connected to an exhaust gas heater 66 at a high temperature part of the cement baking apparatus 40 via a dry gas fan 62 and an indirect heat exchanger 64. As this high temperature part, one or more places such as a suspension preheater, an inlet hood, a rotary kiln, and a cooler can be used. FIG. 1 shows a case where the exhaust gas heater 66 in the high temperature part is provided in the first cyclone C1 of the suspension preheater.
[0020]
The exhaust gas heater 66 preferably has a jacket structure as shown in FIG. 68 is a jacket and 70 is a refractory.
The heating / deodorizing exhaust gas duct 72 at the outlet of the exhaust gas heater 66 branches, one branch duct 78 is connected to the crusher 24, and the other branch duct 81 is connected to the heat exchanger 64. 75 is a bleed gas pipe. Further, the exhaust gas duct 74 of the suspension preheater is sent to the exhaust gas treatment device via a suspension preheater exhaust gas induction fan 76 and a dry pulverizer such as a cement manufacturing device.
[0021]
The heating / deodorization exhaust gas duct 72 is branched on the upstream side of the heat exchanger 64, and as described above, one branch duct 78 is connected to the crusher 24, and a part of the heating / deodorization exhaust gas is decomposed in the crusher 24. It is configured to be circulated.
[0022]
Although the case where the cyclone 28 is used as a dust collector is shown in FIG. 1, a bag filter may be used. When using a cyclone, it is preferable to use a high-efficiency cyclone 28a as shown in FIG. The high-efficiency cyclone 28a includes a cylindrical portion 86 having a linden type, for example, a semi-linden type inlet duct 82, a substantially inverted truncated cone-shaped upper cone 88 connected to the lower end of the cylindrical portion 86, and the upper cone 88. The lower cone 92 is connected to the lower end of the upper cone 88 so as to insert the lower end of the upper cone 88. The lower cone 92 has a discharge port 93 in the lower portion, and the upper end of the cylindrical portion 86 is the outlet portion 84. The inner cylinder 85 is inserted and fixed from above so as to protrude. The inner diameter D1 of the lower end of the upper cone 88 is 0.9 to 1.1 times the inner diameter d of the inner cylinder 85, that is, D1 = 0.9d to 1.1d. The top wall of the lower cone 92 is substantially horizontal. By using the cyclone having such a structure, dust (dry powder) in the airflow from the dry duct 26 can be efficiently collected.
[0023]
The sludge cake receiving room (sludge cake receiving building) 12 has a sealed structure, and is configured to discharge odor constantly or intermittently. The carry-in entrance is preferably a double door. The sludge cake dried from the sludge cake tank 14 is air-dried and mixed and stirred in the mixing unit 22 to adjust moisture. Next, this mixed powder (lump) is pulverized by a pulverizer 24 together with a hot air flow consisting of a part of heating / deodorizing exhaust gas (circulated gas), then dried in a drying duct 26, collected by a cyclone 28, and dried. Get powder. In addition, the crusher 24 is a structure which accompanies a hot air flow, crushing a lump, for example by rotation of a cage.
[0024]
Since the dry powder circulation amount is required several times as much as the input sludge, the efficiency of the dry powder cyclone needs to be 98% or more. If the efficiency is less than 98%, much dust is discharged together with the bleed gas (exhaust gas to the outside of the system), which is meaningless.
The moisture of the sludge cake is about 80%, and the moisture of the dry powder blown into the kiln is preferably 10 to 15% in terms of thermo-economics. In addition, the amount of circulating dry powder is reduced as much as possible so that the water content of the mixed powder is 25 to 30% and handling is easy. For these reasons, the amount of circulating dry powder increases from several times to ten times the solid content of the input sludge.
[0025]
The dry powder extracted by the dry powder supply device 34 is quantified by a quantitative feeder 58, and a fixed amount is blown into the rotary kiln inlet hood 46, before the kiln kiln or / and the calcining furnace 44, and the organic matter in the sludge. Combustion heat is used effectively. It is preferable that the dry powder be blown into the calcining furnace 44. The sludge fired product is cooled by the cooler 50 together with the cement raw material fired product and extracted as a product (cement clinker).
The exhaust gas heater 66 preheated by the heat exchanger 64 is introduced into the exhaust gas heater 66 provided in the high temperature part of the cement baking apparatus, for example, the cyclone C1 at the lowermost stage, heated and deodorized, and heated and deodorized. A part of the dryer exhaust gas is circulated to the crusher 24, and the remaining heat and deodorized air dryer exhaust gas and the exhaust gas from the cyclone 28 are heat-exchanged by the heat exchanger 64 to preheat the exhaust gas from the cyclone 28. To do.
[0026]
The amount of dry powder blown into the rotary kiln 48 is obtained by subtracting the diffused dust from the input sludge. That is, the storage amount of the dry powder supply tank 39 is constant.
In the present invention, a suspension preheater (hereinafter also referred to as SP) exhaust gas is not used as a drying heat source, but the hot air temperature can be increased, the amount of drying heat source gas, the bleed gas is low, and the temperature is low. The thermal efficiency is higher than when SP exhaust gas is used as a drying heat source. Moreover, although the deodorizing effect of the dry powder by SP exhaust gas dust is not exhibited, since the dry powder does not leak out of the system, the problem of odor does not occur.
[0027]
In addition, if the dryer exhaust gas is heated to 600 ° C. or higher, it can be completely deodorized, so the exhaust gas heater 66 is provided in an area where the internal temperature is 700 ° C. or higher. The higher this region is, the more economical the heat transfer area of the heater becomes. In addition, since the cement raw material is always sliding on the inner wall surface inside the calcining furnace 44 and the suspension preheater 42, the heat transfer coefficient is very high.
The odor generated in the sludge cake receiving chamber 12 is supplied to the rotary kiln 48 and / or the calcining furnace 44 by the odor fan 18 and used as combustion air. The odor generated in the sludge cake receiving chamber 12 may be mixed into the dryer exhaust gas.
[0028]
The suspension preheater has four or five stages (four stages as an example in FIG. 1) connected in parallel with a parallel flow heat exchanger (cyclone), and thus has the following characteristics.
(1) When the exhaust gas intensity (Nm ³ / kg-clinker) increases, the higher the temperature, the higher the suspension preheater (SP) exhaust gas temperature, so the SP exhaust gas loss (gas amount x temperature) doubles and heat The impact on consumption is very large.
(2) When the exhaust gas intensity does not increase and the gas temperature decreases due to heat dissipation and heat absorption (evaporation of sludge moisture), the SP exhaust gas temperature also decreases, so the effect on heat consumption is halved. However, if the temperature drops before the calcining furnace, the amount of combustion in the calcining furnace will increase.
(3) If heat is generated after the calcining furnace (burning of sludge organic matter), the SP exhaust gas temperature rises, so the heat consumption improvement effect is halved.
[0029]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects.
(1) Since part of the heated and deodorized exhaust gas from the dryer is circulated to the crusher as a drying heat source, the amount of exhaust gas from the dryer and the amount of bleed gas can be reduced. Can be planned.
(2) Since a heat exchanger for preheating the exhaust gas from the air dryer is provided, heat consumption is not deteriorated. In addition, since the preheated dryer exhaust gas is heated and deodorized at the high temperature portion of the cement baking apparatus, the dryer exhaust gas can be deodorized and released to the atmosphere.
(3) Sludge cake has a moisture content of about 80% and is very adherent, but it is adjusted to a mixed powder with a moisture content that does not adhere when mixed with dry powder, preventing adhesion troubles in transportation equipment, dryers, etc. Is done.
(4) Since dry powder is blown into a cement firing device (hereinafter referred to as firing equipment), sludge can be used and treated as a cement raw material and fuel without increasing the amount of exhaust gas and suppressing the increase in calorific value.
(5) Since the dry powder and the cement raw material are well mixed, the quality of the cement clinker is stabilized.
(6) The deodorizing exhaust gas can be completely deodorized by indirectly heating the exhaust gas of the dryer with an exhaust gas heater at a high temperature part in the firing facility.
(7) Since the organic matter in the dust burns in the exhaust gas heater, the decrease in the gas temperature in the firing facility can be reduced.
(8) When the dust collector of the air dryer is made highly efficient, the sludge dry powder discharged together with the bleed gas can be reduced, so that the sludge combustion heat can be used effectively in the firing equipment. The heat consumption for firing can be reduced.
(9) By the above (2), (4), (5), and (7), it is possible to significantly increase the sludge treatment amount that was conventionally about 10% of the cement production amount.
(10) Since the exhaust gas is circulated to the crusher, the moisture content in the exhaust gas can be adjusted according to the exhaust gas circulation amount, and the optimal equipment such as dry powder circulation amount, deodorizing effect, heat consumption, equipment cost, etc. should be planned. Can do.
(11) Since the dry powder supply tank provided with the dry powder supply device serves as a buffer, it is not necessary to stop the dry powder input to the baking facility even if a trouble occurs between receiving the sludge cake and supplying the dryer.
(12) When the odor generated when the sludge cake is received is recovered as the primary air for combustion of the baking facility, it can be deodorized without deteriorating heat consumption. In addition, you may mix the odor generated at the time of sludge cake acceptance into dryer exhaust gas.
[Brief description of the drawings]
FIG. 1 is a systematic schematic configuration diagram showing a sludge treatment apparatus according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view illustrating an example of the exhaust gas heater in FIG.
FIG. 3 is an elevation explanatory view showing an example of a cyclone in FIG. 1;
[Explanation of symbols]
10 Vehicle 12 Sludge cake reception room (sludge cake reception building)
14 Sludge Cake Tank 16 Sludge Cake Discharger 18 Odor Fan 20 Airflow Dryer 22 Mixing Section 24 Crusher 26 Drying Duct 28 Cyclone 28a High Efficiency Cyclone 30 Dryer Exhaust Duct Duct 32 Discharge Machine 34 Dry Powder Feeder 36 Circulating Dry Powder Feeder 38 Sludge Cake inlet 39 Dry powder supply tank 40 Cement calciner 42 Suspension preheater 44 Calciner 46 Inlet hood 48 Rotary kiln 50 Cooler 52 Cement raw material inlet 54 Calciner burner 56 Kiln burner 58 Metering feeder 60 Dry powder air transport device 62 Dry gas Fan 64 Heat exchanger 66 Exhaust gas heater 68 Jacket 70 Refractory 72 Heating / deodorizing exhaust gas duct 74 Exhaust gas duct 75 Bleed gas pipe 76 Suspension preheater exhaust gas induction fan 78, 81 Branch duct 82 Inlet duct 84 Outlet portion 85 Inner tube 86 Cylindrical portion 88 Upper cone 92 Lower cone 93 Discharge port

Claims (11)

The sludge cake from the sludge cake tank is air-dried and mixed with the sludge circulation dried powder to adjust the moisture, and then the mixed powder is crushed by the crusher of the air-flow dryer and then dried in the drying duct. Dust is collected with a dust collector to obtain dry powder, and a certain amount of this dry powder is blown into a rotary kiln and / or calcining furnace to be used as part of cement clinker firing fuel, and the fired product is cemented It is a method of obtaining a cement clinker by cooling together with a raw material fired product,
The high-temperature part of the cement baking equipment is an exhaust gas heating part that indirectly heats the dryer exhaust gas, and the exhaust gas exhaust gas is introduced into this exhaust gas heating part to heat and deodorize, and a part of the heated and deodorized air dryer exhaust gas is used. It is circulated to the crusher of the air dryer, the increased gas is bleed out of the system, and the remainder of the heated and deodorized air dryer exhaust gas and the air dryer exhaust gas from the dust collector of the air dryer are heat exchanged. Then, a method for treating sludge, characterized by preheating the exhaust gas from the air dryer from the dust collector. The sludge treatment method according to claim 1, wherein the preheated air-flow dryer exhaust gas is heated and deodorized to 600 ° C. or more in the exhaust gas heating section. The method for treating sludge according to claim 1 or 2, wherein the circulation amount of the dry powder mixed in the sludge cake is adjusted so that the water content of the mixed powder is 30% or less. The sludge treatment method according to claim 1, 2 or 3, wherein the odor generated when the sludge cake is received in the sludge cake tank is the rotary kiln of the cement baking apparatus and / or the combustion air of the calciner. A mixing unit for mixing the sludge cake and a part of the dry powder dried by the air dryer described later, a crusher for crushing the mixed powder from the mixing unit together with a hot air flow, and the crushed powder A substantially vertical drying duct for air-flow drying, a dust collector connected to the upper end of the drying duct, a dryer exhaust gas duct connected to the top of the dust collector, and a discharger at the bottom of the dust collector An air dryer having a dry powder supply tank attached with a dry powder supply device connected via
A suspension preheater composed of a plurality of cyclones, a calciner connected to the lowermost cyclone of the suspension preheater, a rotary kiln connected to the calciner and the lowermost cyclone via an inlet hood, A device comprising a cement firing device having a cooler coupled to the outlet of the rotary kiln,
The dry powder feeder of the air dryer is connected to the rotary kiln inlet hood or / and calcining furnace via a quantitative feeder and dry air transport device,
The dry exhaust gas duct of the air flow dryer is connected to the exhaust gas heater at the high temperature part of the cement firing device via an indirect heat exchanger, and the heating / deodorizing exhaust gas duct at the outlet of this exhaust gas heater is branched. The sludge is characterized in that a branch duct is connected to the crusher, and the other branch duct is connected to the indirect heat exchanger so that a part of the heated / deodorized exhaust gas is circulated to the crusher. Processing equipment. The sludge treatment apparatus according to claim 5, wherein the exhaust gas heater has a jacket structure. The sludge treatment apparatus according to claim 5 or 6, wherein the high-temperature portion of the cement baking apparatus is at least one of a suspension preheater, an inlet hood, a rotary kiln, and a cooler. The sludge treatment apparatus according to claim 5, 6 or 7, wherein the dust collector is a cyclone. The sludge treatment apparatus according to claim 5, 6 or 7, wherein the dust collector is a bag filter. A cyclone is connected so that a cylindrical part having a linden-type inlet duct, a substantially inverted truncated cone-shaped upper cone connected to the lower end of the cylindrical part, and a lower end of the upper cone inserted into the lower part of the upper cone. The lower cone having a substantially inverted conical shape having a discharge port in the lower part and an inner cylinder inserted from above so that the upper end protrudes as an outlet part at the center of the cylindrical part, and has an inner diameter D1 at the lower end of the upper cone. 9. The sludge treatment apparatus according to claim 8, wherein 0.9 to 1.1 times the inner diameter d of the inner cylinder, that is, D1 = 0.9 to 1.1d. The sludge treatment apparatus according to claim 10, wherein the top wall of the lower cone is substantially horizontal.

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