AU2013227605A1 - Sludge disposal facility - Google Patents

Abstract

Provided is sludge treatment facility that can spray contaminated water evenly in water-containing sludge that has been deposited in a sludge hopper. This sludge treatment facility (1) is provided with a contaminated water recovery mechanism (4) which comprises: a contaminated water recovery tank (3) for recovering contaminated water (6) resulting from cleaning either a sludge hopper (2) that stores water-containing sludge (5) transported from a sewage treatment plant by truck (8) or pipes in the sludge treatment facility (1); and a contaminated water return pipe (7) that transports the water from the contaminated water recovery tank (3) to the sludge hopper (2). The water-containing sludge (5) that is stored in the sludge hopper (2) is treated by a cement manufacturing process (13). A water spraying unit (7a) on the sludge hopper (2) side of the contaminated water return pipe (7) is disposed above the dropping position for the water-containing sludge (5) into the sludge hopper (2) from the truck (8) such that the contaminated water (6) is sprayed onto the peak (5a) of the water-containing sludge (5) that has collected within the sludge hopper (2).

Description

1 DESCRIPTION SLUDGE DISPOSAL FACILITY 5 TECHNICAL FIELD [0001] The present invention relates to a sludge disposal facility, in which sewage sludge or the like discharged from a sewage disposal facility is fed into a cement kiln to 10 be converted to cement raw material. Priority is claimed on Japanese Patent Application No. 2012-042786, filed February 29, 2012, the content of which is incorporated herein by reference. BACKGROUND ART 15 [0002] In recent years, as a sludge treatment of sewage sludge or the like discharged from a sewage disposal facility, a cement raw material producing technology, in which sewage sludge cake is directly fed into a clinker burning furnace, has been proposed and put to practical used. In the technology: sewage-dewatered sludge (wet sludge) treated to 20 an extent of about 80% of moisture content is brought in by a truck (a motor truck); the sludge is fed directly into a cement kiln, which is a cement clinker burning furnace, by a pressure feed pump; and the sludge is heated at a high temperature. By following the above-described procedures, water and combustible materials are vaporized and combusted, respectively, to sinter the ash of inorganic-based compounds with cement raw 25 materials as a clinker, which is an intermediate product of cement.

2 [0003] In such a treatment technology, wastage is not produced as by-product at all since the ash of inorganic-based compounds in the sewage-dewatered sludge is converted to cement raw materials by utilizing the ash as a part of clay raw materials. Because of 5 this, the above-explained technology for producing cement raw materials is an excellent technology in view of environment protection. [0004] As an example of the treatment technology, a sludge disposal facility is proposed in Patent Literature I (PTL 1). The sludge disposal facility disclosed in PTL I has a 10 wastewater collecting mechanism that collects wastewater produced during washing of: a sludge hopper storing wet sludge; or a pipe connected to the sludge hopper, and returns it to the sludge hopper. The wastewater collecting mechanism includes: a wastewater collecting tank, which collects and stores the wastewater; a wastewater returning pipe, which connects the wastewater collecting tank and the sludge hopper; and a wastewater 15 returning pump, which is provided to the wastewater returning pipe and returns the wastewater in the wastewater collecting tank to the sludge hopper. In the sludge disposal facility disclosed in PTL 1, the wet sludge stored in the sludge hopper is processed by feeding it in a rotary kiln [0005] 20 In the above-explained conventional sludge disposal facility, the wet sludge transported from a sewage disposal facility by a track is stored in the sludge hopper, and it is transferred to the kiln inlet part of the rotary kiln by a pressure feed pump though a sludge introducing pipe from the sludge hopper. [0006] 25 However, in the conventional sludge disposal facility, the wet sludge 5 is poured 3 in from the inlet 9 provided on one side of the sludge hopper 2 during pouring in and storing the wet sludge to the sludge hopper by the truck as shown in FIG. 5. Thus, the wet sludge 5 is not stored evenly in the sludge hopper 2 but deposited lopsidedly to the one side of the sludge hopper 2. In this occasion, the wastewater 6 is not mixed with the wet 5 sludge 5 and only the wastewater 6 alone is accumulated in the other side of the sludge hopper 2, since the spraying part 7a of the wastewater returning pipe 7, which returns the wastewater 6 from the wastewater collecting tank to the sludge hopper 2, is placed on the other side of the sludge hopper 2, which is on the opposite side to the one side with the inlet 9 of the wet sludge 5 loaded on the truck 8, in the conventional sludge disposal 10 facility. This causes uneven water content distribution within the wet sludge 5 during introducing of the wet sludge 5 into the rotary kiln increasing strain on the rotary kiln in the case where the water content is increased. [0007] Also, in the case of utilization of the facility during winter or in a cold area, the 15 wastewater 6 in the wastewater collecting tank freezes. In that case: the wastewater collecting tank; the wastewater returning pump and the wastewater returning pipe that returns the wastewater 6 to the sludge hopper 2; or the like could be broken due to the freezing wastewater. [0008] 20 The sludge hopper 2 and the pipe connected to the sludge hopper 2 are cleaned by cleaning water periodically. Such cleaning is appropriately performed. The wastewater 6 generated during the above-explained cleaning process is returned to the sludge hopper 2 through the wastewater collecting mechanism. Then, the returned wastewater is introduced into the rotary kiln and processed. However, the wet sludge 5 left in the deck 25 8a of the truck 8 stuck to the deck 8a due to drying since the truck 8, which transported 4 the wet sludge 5 from the sewage disposal facility, leaves the sludge disposal facility directly after pouring the wet sludge 5 in the sludge hopper 2. Also, an additional wastewater treatment is needed when the deck 8a is cleaned in the other location. [Related Art Document] 5 [Patent Literature] [0009] PTL 1: Japanese Unexamined Patent Application, First Publication No. 2002-224692 (A) 10 DISCLOSURE OF INVENTION [Problems to be Solved by the Invention] [0010] The present invention was made under above-described circumstances. The purpose of the present invention is to provide a sludge disposal facility capable of 15 spraying wastewater evenly on the wet sludge deposited in the sludge hopper. [Means for Solving the Problem] [0011] In order to solve the above-described problem, the present invention has aspects indicated below. 20 (1) A sludge disposal facility including, a wastewater collecting mechanism including: a wastewater collecting tank; and a wastewater returning pipe, the wastewater collecting tank being configured to collect a wastewater produced during washing of: a sludge hopper that stores a wet sludge transported from a sewage disposal facility by a truck; or a pipe provided in the sludge 25 disposal facility, the wastewater returning pipe being configured to deliver a water from 5 the wastewater collecting tank to the sludge hopper, wherein the sludge disposal facility is configured to process the wet sludge stored in the sludge hopper in a cement producing process, and a spraying part, which is provided to the wastewater returning pipe on a side of 5 the sludge hopper, is placed above a drop position of the wet sludge in the sludge hopper from the truck in such a way that the spraying part is configured to spray the wastewater on a top part of the wet sludge deposited in the sludge hopper. [0012] (2) The sludge disposal facility according to (1) described above, wherein 10 an inside-pipe passage is provided to the spraying part of the wastewater returning pipe in a vertical direction, and a baffle plate is placed at a position below and spaced apart from a lower end of the spraying part in a horizontal direction. [0013] 15 (3) The sludge disposal facility according to (1) or (2) described above, wherein a circulation device is provided to the wastewater collecting tank, the circulation device being configured to prevent freezing of the wastewater by circulating the wastewater stored in the wastewater collecting tank. [0014] 20 (4) The sludge disposal facility according to (1) to (3) described above, further including a sprinkler system configured to wash the truck by a cleaning water after the truck pours the wet sludge into the sludge hopper. [Effects of the Invention] [0015] 25 According to the aspects (1) to (4) of the present invention, the wastewater can 6 be sprayed on the surface of the wet sludge deposited in a mound shape along the slope of the mound from the top part of the mound when the wastewater collected in the wastewater collecting tank is sprayed in the sludge hopper in which the wet sludge is deposited, since the spraying part, which is provided to the wastewater returning pipe on 5 a side of the sludge hopper, is placed above a drop position of the wet sludge poured from the inlet of the sludge hopper by the truck. Because of this, storing the wastewater and the wet sludge in a state where they are separated can be prevented. [0016] According to the aspect (2) of the present invention, the inside-pipe passage is 10 provided to the spraying part of the wastewater returning pipe in a vertical direction, and a baffle plate is placed at a position below and spaced apart from a lower end of the spraying part in a horizontal direction. Thus, the wastewater can be spread evenly on the entire surface of the wet sludge deposited in the mound shape from the top part to the base part. As a result, the wet sludge with less variation of water content can be 15 introduced into the cement kiln, for example when the wet sludge stored in the sludge hopper is introduced in the cement kiln. Thus, strain on the cement kiln can be reduced. [0017] According to the aspect (3) of the present invention, the circulation device is provided to the wastewater collecting tank, the circulation device being configured to 20 prevent freezing of the wastewater by circulating the wastewater stored in the wastewater collecting tank. Thus, breakage of the wastewater collecting tank, each of pipes and pumps connected the wastewater collecting tank, or the like due to freezing of the wastewater can be prevented even if the sludge disposal facility was used in a cold area. [0018] 25 According to the aspect (4) of the present invention, the sludge disposal facility 7 further includes a sprinkler system configured to wash the truck by cleaning water after the truck pours the wet sludge into the sludge hopper. Thus, by cleaning the truck after it poured the wet sludge in the sludge hopper, the wet sludge stuck to the truck that transported the wet sludge can be cleaned easily. As a result, the wet sludge can be 5 cleaned off before it is dried out. Thus, the truck can be cleaned with a relatively small amount of cleaning water. [0019] Also, the wastewater can be introduced in the cement kiln and processed by collecting the wastewater produced during washing and delivering it to the wastewater 10 collecting tank. Because of this, the wet sludge left in the truck can be treated easily, reducing negative impact on the environment. BRIEF DESCRIPTION OF THE DRAWINGS [0020] 15 FIG. I is a schematic diagram showing an embodiment of a sludge disposal facility related to the present invention. FIG. 2A shows an embodiment of a sludge disposal facility related to the present invention. FIG. 2A is a diagram of: a facility receiving the sludge; and a sludge hopper-housing facility in an underground pit. 20 FIG. 2B shows an embodiment of a sludge disposal facility related to the present invention. FIG. 2B is a diagram of a sludge hopper-housing facility in an underground pit. FIG. 3 is a plan view of the facility receiving the sludge in FIGS. 1, 2A, and 2B. FIG. 4 is an illustrative drawing indicating the location of the spraying part, 25 which is provided to the wastewater returning pipe on a side of the sludge hopper, in an 8 embodiment of a sludge disposal facility related to the present invention. FIG. 5 is an illustrative drawing indicating the location of the spraying part, which is provided to the wastewater returning pipe on a side of the sludge hopper, in a conventional sludge disposal facility. 5 BEST MODE FOR CARRYING OUT THE INVENTION [0021] The sludge disposal facility I related to the first embodiment of the present invention mainly includes: the manufacturing facility13 (cement producing process) with 10 the preheater 23, which preheats the cement raw materials C, and the dry-process rotary kiln 18; the sludge receiving facility 15, which receives the truck 8 transporting the wet sludge 5 from the sewage disposal facility; the spraying device 11, which is placed in the sludge receiving facility 15; the sludge hopper-housing facility 28, which has the sludge hopper 2 storing the wet sludge 5 and the wastewater collecting tank 3 that collects and 15 stores the wastewater 6 produced during washing of the sludge hopper 2 or the pipe connected to the sludge hopper 2; and the sludge pouring mechanism 16, which pours the wet sludge 5 from the side of the kiln inlet part 19a of the dry-process rotary kiln 18 through the sludge introducing pipe 17 as shown in FIG. 1. The wet sludge 5 is dehydrated sewage sludge including roughly 80% of water 20 content. In this embodiment, the wet sludge is the one without a pre-treatment such as additive addition and the like. However, wet sludge with the pre-treatment such as additive addition and the like can be used too. As the truck 8, the sealed container equipped vehicle capable of sealing the wet sludge 5 on the deck 8a can be used, for example. 25 [0022] 9 The preheater 23, which preheats the cement raw materials C that are crushed by the raw material mill (not shown in the drawing) and fed from the chute S, is connected to the kiln inlet part 19a of the dry-process rotary kiln 18 through the housing 22 in the manufacturing facilityl3. Thus, the manufacturing facility13 is configured in such a way 5 that the cement raw materials C are introduced in the kiln inlet part 19a through the preheater 23 and the housing 22. [0023] The preheater 23 is mainly includes: the cyclones 23a continuously provided in multiple stages in the vertical direction; and the rising duct 23b that connects each of the 10 cyclones 23a in such a way that the exhaust gas from the dry-process rotary kiln 18 rises therein. The symbol F is the induction fan. It allows the exhaust gas from the dry-process rotary kiln 18 to be exhausted to outside by letting the exhaust gas be moved up though each of the cyclones 23a and the rising duct 23b [0024] 15 The dry-process rotary kiln 18 includes: the cylindrically-shaped kiln shell 19, in which the housing 22 is connected to the kiln inlet part 19a, inclined downward toward the downstream side to a certain degree, and capable of rotating in its circumferential direction; the burner 20, which is provided to the downstream side of the kiln shell 19 and uses heavy oil or pulverized coal as fuel; and the clinker cooler 21, which is provided 20 below the downstream of the kiln shell 19. The rising duct 23a, which is positioned at the lowermost part of the preheater 23, is connected to the upper portion of the housing 22. The bottom surface 22a is the slant surface incline upward toward the upstream side. [0025] The sludge pouring mechanism 16 is provided in order to pour the wet sludge 5 25 from the side of the kiln inlet part 19a of the dry-process rotary kiln 18. The sludge 10 pouring mechanism 16 is connected to the sludge hopper 2 storing the wet sludge 5 transported by the truck 8. The sludge pouring mechanism 16 includes: the sludge introducing pipe 17, which pumps the wet sludge 5 through the pressure feed pump 24; and the sludge inlet 14, in which the tip of the sludge introducing pipe 17 is provided 5 above the bottom surface 22a of the housing 22 for the wet sludge 5 to be dropped on the bottom surface 22a. That is, the sludge inlet 14 is provided to the inner wall of the housing 22, which is the connecting part between the preheater 23 and kiln inlet part 19a. [0026] As shown in FIG 3, the building 15b and the sludge receiving rooms 15a, both 10 of which are in a rectangular shape in the plan view, are connected to the sludge receiving facility 15. Truck 8 can go in and out through each of standing wall surfaces continuously connected to the building 15b. Multiple nozzles (sprinkler system) 11 are provided in the building 15b on the ceiling side. The deck 8a of the truck 8 is washed by spraying cleaning water with the nozzles 11. Also, the opening part 15c, though which 15 the wet sludge 5 is poured in the sludge hopper 2, is provided at the bottom surface of the building 15b. The cleaning water supplying pipe 42, which feeds the cleaning water to the nozzles by the truck-cleaning-water pump 40, is connected to the nozzles 11 though the valve 41. On the base end side of the cleaning water supplying pipe 42, a cleaning water supplying source is connected (not shown in the drawing). 20 [0027] The underground pit 12 is buried under the building I5b in the sludge receiving facility 15. As shown in FIG 2a, the sludge hopper-housing facility 28 is provided in the underground pit 12. As shown in FIG 2B, a pair of the sludge hopper 2 is housed in the underground pit 12 in the sludge hopper-housing facility 28 (the lower structure). Also, 25 the sludge hopper-housing facility 28 includes the wastewater collecting mechanism 4, 11 which collects the wastewater 6 produced during washing of each sludge hopper 2 or a pipe connected to each sludge hopper 2 and returns the wastewater 6 to the sludge hopper 2. Each of two sludge hoppers 2 has a lid part 2a, which can be opened and closed independently. 5 [0028] Also, the storing pit 30 is provided to the floor part of the underground pit 12 storing the wastewater 6 temporally. Furthermore, the collection pipe 31, which connects the storing pit 30 and the wastewater collecting tank 3 through the check valve 31 a, is connected to the storing pit 30. The collection pipe 31 includes the wastewater collecting 10 pump 32, which is a submerged pump feeding the wastewater in the storing pit 30 to the wastewater collecting tank 3. [0029] Also, the wastewater collecting mechanism 4 includes: the wastewater collecting tank 3, which collects and stores the wastewater 7; the wastewater returning pipe 7, 15 which forms connection from the wastewater collecting tank 3 to each of the sludge hoppers 2; and the wastewater returning pump 25, which is provided to the wastewater returning pipe 7 and a submerged pump feeding the wastewater 6 in the wastewater collecting tank 3 to the sludge hopper 2. Also, the stirring blade (circulating device) 10 is provided to the bottom part of the wastewater collecting tank 3. The stirring blade 10 is 20 provided to be rotated freely by the drive unit (not shown in the drawing) in order to prevent freezing of the wastewater 6 by forming convection in the wastewater 6 collected and stored in the wastewater collecting tank 3. [0030] Also, in the wastewater returning pipe 7, the spraying part 7a, from which the 25 wastewater 6 on the side of the sludge hopper 2 is discharged when the wet sludge 5 of 12 the sludge hopper 2 is poured in from the side of the inlet 9 by the truck 8, is provided above the location on which the wet sludge 5 drops as shown in FIG. 4. In other words, the center of the spraying part 7a of the wastewater returning pipe 7 is aligned to the positon of the top part 5a of the wet sludge 5. 5 [0031] The inside-pipe passage 7b, which is a flow passage of the wastewater 6, is provided in the vertical direction in the spraying part 7a of the wastewater returning pipe 7. Also, the baffle plate 7c is provided to the spraying part 7a so that the discharged wastewater 6 is scattered from above on the top part 5a of the deposited wet sludge 5. 10 The baffle plate 7c is provided at the position below and space apart from the lower end part of the spraying part 7a horizontally. [0032] Furthermore, the wastewater retuning pipe 7 is interposed by the branched pipe 7d and connected to each of the pair of sludge hoppers 2. Each of the check valves 26 15 and each of the flexible joints 27 are provided in the middle of the branched pipes 7d. Also, the changeover valves 29, which function as a switching mechanism capable of returning the wastewater 6 to at least one of the two sludge hoppers 2 selectively, are provided in the middle of the branched pipes 7d on the upstream side of the check valves 26. 20 [0033] The sludge introducing pipe 17 branched from the sludge introducing pipe 17 through the sewer valve 33 and connected to the wastewater collecting tank 3. The wastewater-bringing back pipe 34, which feeds the wastewater 6 in the sludge introducing pipe 17 to the wastewater collecting tank 3, is connected to the sludge 25 introducing pipe 17.

13 The wastewater collecting tank 3 is provided to the position below the dry-process rotary kiln 18. The sludge introducing pipe 17 is arranged inclining upward from the wastewater collecting tank 3 to the dry-process rotary kiln 18. [0034] 5 The cleaning water supplying pipe 36, which feeds cleaning water into the pipe with the cleaning pump 35, is connected to the sludge introducing pipe 17 through the valve 37 on the downstream side from the branching point of the wastewater-bringing back pipe 34 at the base end side. On the base end side of the cleaning water supplying pipe 36, a cleaning water supplying source is connected (not shown in the drawing). Also, 10 the cleaning device inserting part 38, through which a cleaning device is inserted into the pipe, is provided to the sludge introducing pipe 17 on the downstream side from the connecting part to the cleaning water supplying pipe 36 at the base end side. [0035] The cleaning device is in a spherical shape having a diameter larger than the 15 inner diameter of the sludge introducing pipe 17. A sponge or the like soaked in soapy water is used as the cleaning device. By using the sponge in a spherical shape as explained above, it can be pushed forward smoothly cleaning inside of the pipe by the clean water even at the part in which the pipe is bent or the inner diameter is varied. Also, by having the cleaning device containing soapy water, it can be easily inserted and 20 pushed forward in the pipe. The level meter 39, which measures the amount of the wastewater, is provided to each of the storing pit 30 and the wastewater collecting tank 3. [0036] A wet sludge treatment method and a cleaning method of a truck transporting the wet sludge 5, in which the sludge disposal facility 1 configured as explained above is 25 used, are explained. The solid arrows in FIG. I indicate the transport direction of the 14 cement raw materials C or the wet sludge 5. The dotted arrows in FIG. I indicate the gas flow direction. [0037] First, the cement raw materials C are poured in the rising duct 23b on the top 5 part of the preheater 23. The cement raw materials C move down while exchanging heat with the exhaust from the dry-process rotary kiln 18, which moves up from the rising duct 23b on the bottom part of the preheater 23. The cement raw materials C are inserted in the rotating dry-process rotary kiln 18 through the kiln inlet part 19a. On another front, the wet sludge 5 transported from the sewage disposal facility by the truck 8 is temporary 10 stored after the truck 8 being parked in the sludge receiving room 15a of the sludge receiving facility 15 from behind and the wet sludge 5, which is loaded on the truck 8, being poured by opening a lid part 2a of any one of the sludge hoppers 2. On this occasion, the wet sludge 5 loaded on the deck 8a of the truck 8 is dropped from the inlet 9 of the sludge hopper 2 as shown in FIG 4. Because of this, the wet sludge 5 is 15 deposited on the same drop position always to be deposited in a mound shape on the side of the inlet 9 of the sludge hopper 2 forming the top part 5a. [0038] Next, the wet sludge 5 stored in the sludge hopper 2 is pumped from the sludge introducing pipe 17 to the sludge inlet 14 by the pressure feed pump 24. Then, the 20 pumped wet sludge 5 is introduced in the dry-process rotary kiln 18 from the sludge inlet 14. The wet sludge 5 introduced in the dry-process rotary kiln 18 as described above is burned by heat of the burner 20 with the cement raw materials C to be the cement clinker C1. Then, the cement clinker C1 is discharged after being cooled by the clinker cooker 21 provided on the downstream side of the kiln shell 19. 25 Furthermore, the clinker C1 is crushed with plaster with a finishing mill (not 15 shown in the drawing) to be cement, which is the final product. [0039] Next, a treatment method of the wastewater 6 produced during washing a pair of sludge hoppers 2 and the pipes connected to each of the sludge hoppers 2 is explained. 5 First, the wastewater 6 produced during washing: each of sludge hoppers 2; and the pipes in the underground pit 12 is collected in the storing pit 30 in the floor part of the underground pit 12 to be stored temporally. Then, the wastewater 6 stored in the storing pit 30 is fed to the wastewater collecting tank 3 through the collection pipe 31 by the wastewater collecting pump 32 to be stored. 10 [0040] Next, the wastewater 6 in the wastewater collecting tank 3 is returned in the sludge hopper 2 through the wastewater returning pipe 7 by the wastewater returning pump 25. On this occasion, at least one of the two sludge hoppers 2 is selected as the returning destination by: appropriately controlling the amount of the wastewater 6 to be 15 returned depending on the state (particularly the concentration of water) of the wet sludge 5 in the sludge hoppers 2; and selecting the branched pipe 7d sending the wastewater 6 by opening or closing the wastewater-returning changeover valve 29 as necessary. [0041] The wastewater 6 is sprayed from the spraying part 7a of the wastewater 20 returning pipe 7 when the wastewater 6 is supplied in the sludge hoppers 2 from the wastewater returning pipe 7. At this time, the wastewater 6 is scattered all around through the baffle plate 7c provided to the spraying part 7a, since the spraying part 7a is placed above the top part 5a of the wet sludge 5 deposited in the mound shape in the sludge hopper 2. Thus, the wastewater 6 is evenly sprayed on the wet sludge 5 deposited in the 25 mound shape from the top part 5a to the base part. The wastewater 6, which is sprayed on 16 the wet sludge 5 as explained above, mixes with the wet sludge 5. Then, as explained above, the mixture is squeezed to the sludge inlet 14 from the sludge hopper 2 through the sludge introducing pipe 17 by the pressure feed pump 24. Then, the mixture is fed in the dry-process rotary kiln 18 from the sludge inlet 14. 5 [0042] A treatment method of the wastewater 6 produced during washing the sludge introducing pipe 17 with cleaning water is explained. First, in order to wash the inside of the sludge introducing pipe 17, the cleaning device is inserted from the cleaning device inserting part 38. Then, the valve 37 is opened 10 to feed the cleaning water in the sludge introducing pipe 17 by the cleaning pump 35 though the cleaning water supplying pipe 36. At this time, in order to prevent the cleaning water from flowing to the side of the sludge hopper 2, the upstream side of the sludge introducing pipe 17 is closed by a valve not shown in the drawing. Also, the sewer valve 33 is closed to prevent the cleaning water from flowing in the wastewater 15 collecting tank 3. [0043] The cleaning water fed in the sludge introducing pipe 17 pushes the cleaning device in the pipe forward to the dry-process rotary kiln 18 and cleans the inside of the pipe at the same time. After cleaning the sludge introducing pipe 17 as explained above, 20 the wastewater 6 in the sludge introducing pipe 17 is collected in the wastewater collecting tank 3. That is, by closing the valve 37 and opening the sewer valve 33, the wastewater 6 in the sludge introducing pipe 17, which is arranged inclined as described above, flows into the wastewater collecting tank 3 through the wastewater-bringing back pipe 34 due to its own weight. Then, based on the state of the wet sludge in the sludge 25 hoppers 2, the collected wastewater 6 is sprayed on the wet sludge 5 in the sludge 17 hoppers 2 through the wastewater returning pipe 7 appropriately as explained above. [0044] A washing method of a truck 8 transporting the wet sludge 5, and a treatment method of the wastewater 6 produced during washing the truck 8 are explained. 5 First, the truck 8 is parked in the sludge receiving room 15a of the sludge receiving facility 15, and the wet sludge 5 transported from the sewage disposal facility is poured in from any one of the inlets 9 of the two sludge hopper 2. Then, cleaning water is sprayed from the multiple nozzles II all together in a state where the deck 8a is kept being inclined. At this time, the lid part 2a of the sludge hopper 2 is closed. 10 [0045] The wet sludge 5 left in the deck 8a is cleaned by the cleaning water sprayed from the multiple nozzles 11. This cleaning water is delivered from the cleaning water supplying source by the truck-cleaning water pump 40, traveling from the cleaning water supplying pipe 42 interposed by the valve 41 to the nozzles 11. By spraying the cleaning 15 water for a certain period of time, the wet sludge 5 left on the deck 8a is washed away. [0046] The wastewater 6a produced during washing flows in the underground pit 12 from the floor surface of the building 15b of the sludge receiving facility 15. Then, the wastewater 6a is collected in the storing pit 30 provided to the floor part of the 20 underground pit 12 to be stored temporally as wastewater 6. The, the wastewater 6, which is stored in the storing pit 30, is fed to the wastewater collecting tank 3 through the collection pipe 31 by the wastewater collecting pump 32 to be stored. Then, the wastewater 6 collected and stored in the wastewater collecting tank 3 is sprayed on the wet sludge 5 in the sludge hoppers 2 through the wastewater returning pipe 7 25 appropriately as explained above depending on the state of the wet sludge 5 in the sludge 18 hoppers 2. [0047] The wet sludge 5 sprayed on by the wastewater 6 as explained above is squeezed to the sludge inlet 14 through the sludge introducing pipe 17 from the sludge hoppers 2 5 by the pressure feed pump 24. Then, the wet sludge 5 is introduced in the dry-process rotary kiln 18 from the sludge inlet 14 to be burned with the cement raw materials C. [0048] According to the sludge disposal facility I related to the present embodiment describe above, the wastewater 6 can be sprayed on the surface along the slope from the 10 top part 5a of the wet sludge 5 deposited in the mound shape when the wastewater 6 collected in the wastewater collecting tank 3 is sprayed in the sludge hoppers 2 in which the wet sludge is deposited, since the spraying part 7a, which is on the side of the sludge hopper 2 of the wastewater returning pipe 7, is placed above the drop position of the wet sludge 5 poured in from the inlet 9 in the sludge hoppers 2 by the truck 8. Because of this, 15 storing the wastewater 6 and the wet sludge 5 in a state where they are separated can be prevented. [0049] Also, the wastewater 6 can be spread evenly on the entire surface of the wet sludge 5 deposited in the mound shape from the top part 5a to the base part by spraying 20 the wastewater 6 from above the top part 5a of the wet sludge 5 deposited in the mound shape, since: the inside-pipe passage 7b of the spraying part 7a provided to the wastewater returning pipe 7 is provided in the vertical direction; and the baffle plate 7c is placed at a position below and spaced apart from a lower end of the spraying part in a horizontal direction. As a result, the wet sludge 5 with less variation of water content can 25 be introduced into the dry-process rotary kiln 18, when the wet sludge 5 stored in the 19 sludge hopper 2 is introduced in the dry-process rotary kiln 18. Thus, strain on the dry-process rotary kiln 18 can be reduced. [0050] Also, breakage of the wastewater collecting tank 3, each of pipes and the 5 wastewater-returning pump 25 connected to the wastewater collecting tank 3 due to freezing of the wastewater 6 can be prevented even if the sludge disposal facility 1 is used in a cold area or the like, since the freely rotatable stirring blade 10, which prevents freezing of the wastewater by circulating the wastewater 6 stored in the wastewater collecting tank 3, is provided to the bottom part of the collection tank 3. 10 [0051] Also, the wet sludge 5 left on the deck 8a of the truck 8 that transported the wet sludge 5 can be cleaned easily since the sludge receiving facility 15 has the nozzles 11 washing the deck 8a of the truck 8 by cleaning water after the truck 8 loads the wet sludge 5 into the sludge hopper 2. As a result, the wet sludge 5 can be cleaned off before 15 it is dried out. Thus, the truck 8 can be cleaned with a relatively small amount of cleaning water. [0052] Also, the wastewater 6a can be introduced in the dry-process rotary kiln 18 and processed by: collecting the wastewater 6a produced during washing in the storing pit 30 20 provided to the bottom part of the underground pit 12; and delivering the collected wastewater 6a to the wastewater collecting tank 3 from the storing pit 30. Because of this, the wet sludge 5 left in the truck can be treated easily, reducing negative impact on the environment. [0053] 25 Furthermore, the wastewater 6 produced during washing is stored in the 20 wastewater collecting tank 3 by the wastewater collecting mechanism 4, and the amount of the wastewater 6, which is returned by the wastewater -returning pump 25 appropriately, can be controlled based on the state of the wet sludge 5 in the sludge hopper 2, allowing adjusting the water content in the wet sludge 5. Therefore, the 5 wastewater 6 can be returned in the sludge hoppers 2 while adjusting the amount of return. Also, the wet sludge 5 in which water content is properly adjusted can be supplied to the dry-process rotary kiln 18 from the sludge hoppers 2. Thus, strain on the kiln due to water increase can be reduced. [0054] 10 Furthermore, the amount of return to each of sludge hoppers can be adjusted depending on the state of the wet sludge 5 in each of the sludge hoppers 2, since the wastewater collecting mechanism 4 has the wastewater-returning changeover valve 29 capable of bringing back the wastewater 6 to at least any one of the two sludge hoppers 2 selectively. 15 [0055] Also, the wastewater 6 in the sludge introducing pipe 17 can be collected in the wastewater collecting tank 3 directly, since the sludge disposal facility 1 has the wastewater-bringing back pipe 34 that feeds the wastewater 6 in the sludge introducing pipe 17 to the wastewater collecting tank 3. Thus, the large amount of wastewater 6 20 produced during washing of the sludge introducing pipe 17 can be processed easily. [0056] Also, the wastewater 6 in the sludge introducing pipe 17 can be collected in the wastewater collecting tank 3 by utilizing its own weight without using a pump or the like since the sludge introducing pipe 17 is arranged inclining upward from the wastewater 25 collecting tank 3 to the dry-process rotary kiln 18.

21 [0057] Also, formation of air accumulation in the pipe is suppressed for air to run though upward since the wet sludge 5 or the cleaning water is fed upward from the lower part of the sludge introducing pipe 17. Thus, the wet sludge 5 can be easily pumped, and 5 the cleaning water can be easily supplied. [0058] In the above-described embodiments, only the case where the stirring blade 10 is used for the circulating device provided in the wastewater collecting tank 3 is explained. However, the present invention is not limited by the description. Thus, for example, it 10 can be configured in such a way that the wastewater 6 collected in the wastewater collecting tank 3 is circulated by providing a circulation pipe interposed by a pump at the upper and lower parts of the wastewater collecting tank 3. Also, the freezing prevention effect can be improved by providing a heat source unit such as a heater to the outer peripheral of the wastewater collecting tank 3 or the above-mentioned circulation pipe. 15 [0059] Also, in the above-described embodiments, only the case where the level meter 39, which measures each of amounts of wastewater 6, is utilized in the storing bit 30 and the wastewater collecting tank 3 is explained. However, the present invention is not limited by the description. Thus, for example, it can be configured in such a way that: the 20 water concentration of the wet sludge 5 in the sludge hoppers 2 or the like is automatically measured by a sensor or the like; and the amount of the wastewater return from the wastewater collecting tank 3 is automatically controlled based on a signal from the sensor or the like. [0060] 25 Also, in the above-described embodiments, only the case where the wastewater 22 returning pipe 7 is connected to a pair of the sludge hoppers 2 is explained. However, the present invention is not limited by the description. Thus, for example, it can be configured in such a way that the wastewater returning pipe 7 is connected to: one; or 3 or more of sludge hoppers 2. 5 [0061] Also, in the above-described embodiments, only the case where only the wastewater 6 is returned from the wastewater collecting tank 3 to the sludge hoppers 2 is explained. However, the present invention is not limited by the description. Thus, for example, it can be configured in such a way that: the sludge accumulated in the bottom 10 part of the wastewater collecting tank 3 is withdrawn; and a sludge-returning pump for returning the withdrawn sludge to the sludge hopper 2 is provided. [0062] Also, in the above-described embodiments, only the case where the wet sludge 5 in the sludge hopper 2 is introduced in the kiln inlet part 19a of the dry-process rotary 15 kiln 18 is explained. However, the present invention is not limited by the description. Thus, for example, it can be configured in such a way that the wet sludge 5 is introduced in the dry-process rotary kiln 18 after: putting the wet sludge 5 in a pre-firing furnace and then in the rising duct 23b at the lowest part of the preheater 23; or drying the wet sludge 5 20 INDUSTRIAL APPLICABILITY [0063] The sludge disposal facility can be utilized for a sludge disposal facility in which the wet sludge transported from the sewage disposal plant is introduced in the 25 cement kiln to process it directly or after being dried.

23 BRIEF DESCRIPTION OF THE REFERENCE SYMBOLS [0064] 1: Sludge disposal facility 5 2: Sludge hopper 3: Sludge collection tank 4: Sludge collecting mechanism 5: Wet sludge 5a: Top part 10 6: Wastewater 6a: Wastewater 7: Wastewater returning pipe 7a: Spraying part 7b: Inside-pipe passage 15 7c: Baffle plate 8: Truck 8a: Deck 9: Inlet 10: Stirring blade (circulating device) 20 11: Nozzle (spraying device) 12: Underground pit 13: Cement manufacturing facility 15: Sludge receiving facility

Claims (5)

1. A sludge disposal facility comprising, a wastewater collecting mechanism including: a wastewater collecting tank; and 5 a wastewater returning pipe, the wastewater collecting tank being configured to collect a wastewater produced during washing of: a sludge hopper that stores a wet sludge transported from a sewage disposal facility by a truck; or a pipe provided in the sludge disposal facility, the wastewater returning pipe being configured to deliver a water from the wastewater collecting tank to the sludge hopper, wherein 10 the sludge disposal facility is configured to process the wet sludge stored in the sludge hopper in a cement producing process, and a spraying part, which is provided to the wastewater returning pipe on a side of the sludge hopper, is placed above a drop position of the wet sludge in the sludge hopper from the truck in such a way that the spraying part is configured to spray the wastewater 15 on a top part of the wet sludge deposited in the sludge hopper.

2. The sludge disposal facility according to Claim 1, wherein an inside-pipe passage is provided to the spraying part of the wastewater returning pipe in a vertical direction, and 20 a baffle plate is placed at a position below and spaced apart from a lower end of the spraying part in a horizontal direction.

3. The sludge disposal facility according to Claim 1 or 2, wherein a circulation device is provided to the wastewater collecting tank, the circulation device being 25 configured to prevent freezing of the wastewater by circulating the wastewater stored in 25 the wastewater collecting tank.

4. The sludge disposal facility according to Claim 1 or 2, further comprising a sprinkler system configured to wash the truck by a cleaning water after the truck pours 5 the wet sludge into the sludge hopper.

5. The sludge disposal facility according to Claim 3, wherein further comprising a sprinkler system configured to wash the truck by a cleaning water after the truck pours the wet sludge into the sludge hopper. 10