JP2011139985A - Sludge dehydration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently treat sludge in the waste water discharged from a thermal power plant. <P>SOLUTION: A sludge dehydration system includes: a concentration part (60) for concentrating the sludge in the waste water discharged from the thermal power plant; a slurrying part (70) for heating/slurrying the sludge concentrated in the concentration part; and a dehydration part (90) for dehydrating the slurried sludge. The slurrying part has a heat transfer pipeline having heat transfer properties, and a heating mechanism for heating the heat transfer pipeline from the outside thereof, wherein the inside of the heat transfer pipeline is used as the movement space in which the sludge is moved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sludge dewatering system.

  A sludge treatment method is proposed in which sludge is mainly reformed by hydrothermal treatment by heating, the reformed sludge is cooled, and the cooled sludge is filtered and dehydrated (see, for example, Patent Document 1).

JP 2004-243275 A

In a thermal power plant, various industrial wastewater such as flue gas desulfurization equipment wastewater, pipe washing wastewater, and ash treatment wastewater is always discharged in large quantities. Since these waste water contains a large amount of sludge, an efficient sludge treatment system is desired.
This invention is made | formed in view of such a situation, The objective is to process the sludge in the waste_water | drain discharged | emitted in the thermal power plant efficiently.

In order to achieve the above object, a sludge dewatering system according to the present invention includes a concentration unit that concentrates sludge in waste water discharged from a thermal power plant, and a slurry that heats and slurries the sludge concentrated in the concentration unit. A sludge dewatering system comprising a liquefying section and a dewatering section for dewatering the sludge that has been slurried, wherein the slurrying section heats the heat transfer pipe having heat conductivity and the heat transfer pipe from the outside. A heating mechanism, and the inside of the heat transfer pipe is a moving space in which the sludge moves.
According to this sludge dewatering system, when the heat transfer pipe is heated by the heating mechanism, the sludge moving through the moving space is also heated and slurried by a hydrothermal reaction. Thus, since sludge can be slurried in the process of moving the heat transfer pipe, continuous processing becomes possible. As a result, sludge can be efficiently dehydrated. Moreover, the heating degree of sludge can be prescribed | regulated by the length of heat-transfer piping and a heating mechanism, and the moving speed of sludge, and the pressure in the case of slurrying can be prescribed | regulated by the quantity of sludge and the magnitude | size of movement space. For this reason, the conditions for slurrying can be determined with a simple configuration.

The system preferably further includes a pre-dehydration unit that dehydrates the sludge concentrated in the concentration unit and supplies the dewatered sludge to the slurrying unit.
According to this sludge dewatering system, the sludge dehydrated in advance is slurried in the slurrying section, so that the energy required for slurrying can be suppressed.

In the above system, the heating mechanism divides a space into which the heat transfer pipe is inserted, and introduces heating steam into a heating space formed between the heat transfer pipe and the heating mechanism. It is preferable to include a heating pipe for heating the heat transfer pipe from the outside.
According to this sludge dewatering system, the steam in a heated state existing in various places of the thermal power plant can be used as the steam for heating, so that the heat source can be easily acquired.

In the system, it is preferable that a plurality of the heating pipes have an inlet and an outlet for the heating steam and are provided in a state of being arranged in the extending direction of the heat transfer pipe.
According to this sludge dewatering system, the heating temperature can be finely adjusted according to the connection mode of the inlet and outlet of the heating steam. Thereby, the process at the time of slurrying can be optimized.

  In the system, it is preferable that the heating mechanism introduces the heating steam adjusted so that a temperature of the sludge in the moving space is 210 ° C. or lower and 80 ° C. or higher into the heating space. Furthermore, it is more preferable to introduce the heating steam adjusted to be 130 ° C. or lower and 80 ° C. or higher into the heating space.

  ADVANTAGE OF THE INVENTION According to this invention, the sludge in the waste_water | drain discharged | emitted at the thermal power plant can be processed efficiently.

It is a figure explaining the waste water treatment facility in a thermal power plant. It is a figure explaining the dewatering processing equipment of sludge. (A) is sectional drawing explaining the structure of a slurrying part. (B) is a figure explaining the temperature gradient of the steam for a heating in a slurrying part. It is a figure explaining the relationship between slurrying temperature and a process result. It is a figure explaining the dehydration processing equipment provided with the prior dehydration part. It is a figure explaining the relationship between the slurrying temperature and a process result corresponding to embodiment of FIG. It is a figure explaining embodiment provided with a plurality of heating piping, and (a)-(c) is a figure explaining a variation of a connection mode, respectively.

=== First Embodiment ===
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<About wastewater treatment facilities>
As illustrated in FIG. 1, the thermal power plant wastewater treatment facility includes an NS decomposition unit 10, a fluorine treatment unit 20, a nitrogen treatment unit 30, a heavy metal treatment unit 40, a COD treatment unit 50, and a sludge concentration unit. 60.

The NS decomposition unit 10 is a part that decomposes a nitrogen-sulfur compound (NS compound) that is difficult to remove by a biological nitrogen removal process, and gasifies and removes a nitrogen component. The NS decomposition unit 10 includes an NS decomposition tank 11 and a water storage tank 12. The NS decomposition tank 11 is supplied with drainage discharged from the thermal power plant. For example, various types of wastewater such as flue gas desulfurization device wastewater, pipe cleaning wastewater, and ash treatment wastewater are supplied. In the NS decomposition tank 11, the NS compound contained in the waste water is ignited under sulfuric acid acidity to decompose it into ammonium ions (NH ₄ ⁺ ) and sulfate ions (SO ₄ ⁻ ). Nitrogen gas is generated by reacting nitrous acid with this decomposition product. The water storage tank 12 is a part for storing wastewater after being decomposed in the NS decomposition tank 11, and discharges nitrogen gas to the atmosphere by aeration. The waste water stored in the water storage tank 12 is supplied to the fluorine treatment unit 20 by the pump 13.

  The fluorine treatment unit 20 is a part that removes fluorine contained in the wastewater treated by the NS decomposition unit 10. The fluorine treatment unit 20 includes a fluorine treatment tank 21 and a first precipitation tank 22. In the fluorine treatment tank 21, fluorine is coprecipitated as hydroxide together with magnesium and aluminum sulfate in the waste water by adding a flocculant and removed. The 1st sedimentation tank 22 is a part which precipitates the hydroxide etc. which were produced | generated in the fluorine processing part 20, and takes it out as sludge. Since sludge is co-precipitated with magnesium and aluminum sulfate, this sludge contains a lot of inorganic components. Then, the extracted sludge is sent to the sludge concentration unit 60.

  The nitrogen treatment unit 30 is a part that biologically removes nitrogen contained in the waste water. The nitrogen treatment unit 30 includes a first relay tank 31, a nitrogen treatment tank 32, and a second precipitation tank 33. The 1st relay tank 31 is a part which stores the waste_water | drain from the 1st sedimentation tank 22 temporarily. The wastewater stored in the first relay tank 31 is sent to the nitrogen treatment tank 32 by the pump 34. The nitrogen treatment tank 32 is divided into an aerobic bacteria treatment chamber 32a, an anaerobic bacteria treatment chamber 32b, and a nitrogen discharge chamber 32c from the upstream side toward the downstream side. In the aerobic bacteria treatment chamber 32a, aerobic bacteria (nitrite bacteria, nitrate bacteria) that live in the activated sludge of the wastewater are activated by aeration. This oxidizes ammonium salt and organic nitrogen until it becomes nitrite or nitrate. Wastewater after being processed in the aerobic bacteria processing chamber 32a is supplied to the anaerobic bacteria processing chamber 32b. The anaerobic bacteria treatment chamber 32b is provided with a submersible pump, and the stored wastewater is stirred in an anaerobic state. And in the anaerobic bacteria processing chamber 32b, anaerobic bacteria (denitrifying bacteria) that live in the activated sludge reduce nitrite and nitrate until they become nitrogen gas. In order to stably inhabit anaerobic bacteria, the anaerobic bacteria treatment chamber 32b is loaded with nutrients for anaerobic bacteria. Waste water after being treated in the anaerobic bacteria treatment chamber 32b is supplied to the nitrogen discharge chamber 32c. In the nitrogen discharge chamber 32c, nitrogen gas is released into the atmosphere by aeration. The 2nd sedimentation tank 33 is a part which takes out the sludge contained in the waste_water | drain after processing by the nitrogen discharge chamber 32c by precipitation. The extracted sludge is sent to the sludge concentration unit 60.

  The heavy metal processing unit 40 is a part for removing heavy metals contained in the waste water. The heavy metal processing unit 40 includes a second relay tank 41, a heavy metal processing tank 42, and a third precipitation tank 43. The 2nd relay tank 41 is a part which stores the waste_water | drain from the 2nd sedimentation tank 33 temporarily. The wastewater stored in the second relay tank 41 is sent to the heavy metal processing tank 42 by the pump 44. In the heavy metal treatment tank 42, an alkaline chemical such as sodium hydroxide is introduced into the waste water to precipitate the heavy metal as a hydroxide. The pH of the waste water becomes about 10 to 11 by introducing the alkaline chemical. In the present embodiment, a flocculant is added in addition to the alkaline chemical for the purpose of facilitating the recovery of the precipitate. The 3rd sedimentation tank 43 is a part which takes out the hydroxide contained in the waste_water | drain after processed with the heavy metal processing tank 42. FIG. The extracted hydroxide is sent to the fluorine treatment tank 21.

  The COD processing unit 50 is a part that removes COD components (organic matter) contained in the waste water after being processed by the heavy metal processing unit 40. The COD processing unit 50 includes an adjustment tank 51, a sand filtration tower 52, a COD adsorption tower 53, and a neutralization tank 54. The adjustment tank 51 is a part for storing the pH of the wastewater from the heavy metal processing unit 40, and a pH adjuster is charged therein. By introducing the pH adjuster, the pH of the waste water exhibits an acidity of about 3-4. The wastewater stored in the adjustment tank 51 is sent to the sand filtration tower 52 by the pump 55. In the sand filtration tower 52, the waste water after the pH is adjusted in the adjustment tank 51 flows down in the sand, and unnecessary solids are separated by filtration. Wastewater filtered by the sand filter tower 52 is supplied to the COD adsorption tower 53. In the COD adsorption tower 53, the COD component contained in the drained water is adsorbed by a COD adsorption resin (not shown) arranged in the tower. Thereby, the COD component is removed from the waste water. The waste water from which the COD component has been removed is supplied to the neutralization tank 54. The neutralization tank 54 is a part that neutralizes the waste water. For this reason, the neutralizing tank 54 is charged with a pH treatment agent for neutralization, and the pH of the waste water is adjusted to about 7. Then, the neutralized waste water is discharged outside the facility.

  The sludge concentrating part 60 is a part that concentrates the sludge separated from the waste water in the fluorine treating part 20 and the nitrogen treating part 30, and corresponds to a concentrating part that concentrates sludge. The sludge concentration unit 60 includes a concentration tank 61 for concentration. By standing in the concentration tank 61, the sludge is precipitated and the sludge is concentrated. The precipitated sludge is sucked out from the lower part of the concentration tank 61 by the pump 62. The supernatant liquid of the concentration tank 61 is returned to the fluorine treatment tank 21 of the fluorine treatment unit 20.

<About dehydration facilities>
The thermal power plant dewatering treatment facility is a part for dewatering the concentrated sludge discharged from the wastewater treatment facility. As illustrated in FIG. 2, the wastewater treatment facility includes a heating unit 70, a cooling unit 80, and a dehydrating unit 90. The heating unit 70, the cooling unit 80, and the dewatering unit 90 constitute a sludge dewatering system together with the sludge concentrating unit 60.

  The heating unit 70 is a part that is slurried by decomposing the sludge from the concentration tank 61 by a hydrothermal reaction. Therefore, the heating unit 70 corresponds to a slurrying unit that sludges sludge. Details of the heating unit 70 will be described later.

  The cooling unit 80 is a part that cools the temperature of the sludge slurried by the heating unit 70 (referred to as sludge slurry for convenience) to a temperature that can be handled by the dehydrating unit 90. The cooling unit 80 of the present embodiment includes a double pipe (jacket pipe). That is, the cooling unit 80 partitions a heat transfer inner pipe 81 that partitions a slurry flow path through which sludge slurry moves, and a refrigerant flow path through which the inner pipe 81 is inserted and through which a coolant such as water flows. And an outer pipe 82. Then, both end portions of the outer pipe 82 are closed so as to be in a liquid-tight state with respect to the inner pipe. A refrigerant inlet and a refrigerant outlet are provided on the side surface of the end of the outer pipe 82 (not shown). Therefore, the sludge slurry is cooled to a desired temperature by the heat exchange between the sludge slurry and the refrigerant by flowing the sludge slurry through the slurry flow path and flowing the refrigerant through the refrigerant flow path.

  The dewatering part 90 is a part for reducing the moisture contained in the sludge slurry. By reducing the water content, transportation is facilitated when final disposal such as landfill, incineration, and solidification is performed, and energy required for drying can be suppressed. Various types of dewatering units 90 are used. For example, an apparatus that performs dehydration by vacuum dehydration, centrifugal dehydration, or pressure dehydration is used. Vacuum dehydration is a dehydration method in which sludge is sucked onto the filter cloth surface and moisture is sucked by a vacuum suction force. Centrifugal dehydration is a dehydration method in which water and solid content in sludge slurry are separated by centrifugal force. Pressure dehydration is a dehydration method in which moisture and solid content in sludge slurry are separated by pressing or the like. In this embodiment, since it is suitable for the continuous treatment of sludge slurry, a belt press type pressure dehydration apparatus 91 which is a kind of pressure dehydration apparatus is used. The sludge slurry cooled by the cooling unit 80 is supplied to the dehydrator 91 by the pump 92. By being dehydrated by the dehydrator 91, the sludge becomes a sludge cake. This sludge cake is sent to a sludge cake hopper (not shown) and then transported to a final disposal site.

<Details of heating unit 70>
As shown in FIG. 3A, the heating unit 70 according to the present embodiment is configured by a double tube similarly to the cooling unit 80. That is, the heating unit 70 includes an inner pipe 71 that partitions a moving space 71a in which the concentrated sludge in the concentration tank 61 sent from the pump moves, and an outer pipe 72 into which the inner pipe 71 is inserted into the inner space. And have.

  The inner pipe 71 corresponds to a heat transfer pipe, and is constituted by a metallic cylindrical pipe having a heat transfer property such as stainless steel. The reason why a pipe having heat conductivity is used for the inner pipe 71 is to heat the sludge moving in the moving space 71a by heating from the outer peripheral surface side of the inner pipe 71.

  The outer pipe 72 corresponds to a heating pipe (heating mechanism), and is a part that heats the inner pipe 71 from the outside. That is, the space between the inner peripheral surface of the outer pipe 72 and the outer peripheral surface of the inner pipe 71 corresponds to the heating space 72a. And the inner side piping 71 is heated from the outer side by introduce | transducing the steam for a heating into the space 72a for a heating. For this reason, both ends of the outer pipe 72 are closed so as to be airtight with respect to the inner pipe 71.

  Moreover, the cylindrical part 72b used as the inlet of heating steam and the cylindrical part 72c used as an exit are provided in the side surface of the both ends in the outer side piping 72 (not shown). In the present embodiment, a steam inlet is provided on the downstream side in the sludge traveling direction, and a steam outlet is provided on the upstream side. With this configuration, the temperature of the heating space 72a increases from the upstream side to the downstream side of the inner pipe 71 as indicated by reference numerals A, B, P1, and P2 in FIG. For this reason, it is possible to suppress problems such as the sludge flowing through the inner pipe being suddenly heated and bumping.

  In this heating part 70, sludge is heated in the process of flowing through the moving space 71a to the downstream side, and sludge is slurried by a hydrothermal reaction. Therefore, slurry processing of sludge can be performed, and this processing can be performed efficiently. Here, the heating degree of the sludge can be defined by the temperature of the heating steam, the length of the inner pipe 71 and the outer pipe 72, the moving speed of the sludge moving in the moving space 71a, and the like. Moreover, the pressure at the time of slurrying can be prescribed | regulated by the quantity of sludge, the diameter of the movement space 71a, etc. For example, as shown at the right end of FIG. 3A, the pressure during slurrying can be defined by appropriately determining the inner diameter of another pipe connected to the downstream end of the inner pipe 71. Therefore, the slurrying conditions can be determined with a simple configuration.

  The heating unit 70 uses heating steam as a heat source. In a thermal power plant, since steam in a heated state exists everywhere, a heat source can be easily secured by using heating steam.

<Slurry temperature conditions>
Next, temperature conditions during slurrying will be described. FIG. 4 shows the amount of sludge and the moisture content for samples A1 to A3 and samples B1 to B3. Here, the samples A1 to A3 and the samples B1 to B3 are different in the collected thermal power plant.

  Samples A1, A2, and A3 have different slurry temperature conditions and temperature holding times. Specifically, in sample A1, the slurrying temperature is 80 ° C., and the holding time is 0 hour. That is, in sample A1, heating is stopped when the normal temperature slurry is heated to 80 ° C. In sample A2, the slurrying temperature is 130 ° C., and the holding time is 0 hour. In sample A3, the slurrying temperature is 210 ° C. and the holding time is 1 hour. That is, after raising the temperature to 210 ° C., 210 ° C. is maintained for 1 hour. Note that the temperature condition and holding time of the sample B1 are the same as those of the sample A1. Similarly, sample B2 has the same conditions as sample A2, and sample B3 has the same conditions as sample A3.

  Regarding the amount of sludge, the left side of the arrow shows the amount of sludge when a predetermined amount of concentrated sludge is simply dehydrated by the dehydrating unit 90, that is, a comparative example in which no slurrying treatment is performed. On the other hand, the right side of the arrow indicates the amount of sludge when the same amount of concentrated sludge is slurried by the heating unit 70 and then cooled by the cooling unit 80 and dehydrated by the dehydrating unit 90, that is, the slurry treatment in this embodiment. The results (samples A1 to A3, B1 to B3) are shown. In this respect, the water content is the same. That is, the left side of the arrow shows a comparative example, and the right side of the arrow shows the result in the present embodiment.

Regarding samples A1 to A3, the amount of sludge in the comparative example was 111 m ³ , whereas in sample A1 (80 ° C.), the amount of sludge decreased to 54 m ³ despite the same amount of concentrated sludge. . Similarly, the sludge amount of sample A2 (130 ° C.) was 49 m ³ , and the sludge amount of sample A3 (210 ° C.) was 44 m ³ . Regarding the moisture content, the moisture content in the comparative example was 82%, whereas the moisture content of sample A1 was 63%, the moisture content of sample A2 was 59%, and the moisture content of sample A3 was 55%.

Relates samples B1 to B3, the amount of sludge in the comparative example while which was a 95 m ^3, the amount of sludge in the sample B1 (80 ° C.) is 83m ^3, sludge amount of sample B2 (130 ° C.) in the 61m ³ Yes, the amount of sludge of sample B3 (210 ° C.) was 54 m ³ . Regarding the moisture content, the moisture content in the comparative example was 79%, whereas the moisture content of sample B1 was 76%, the moisture content of sample B2 was 67%, and the moisture content of sample A3 was 63%.

  Although there is a difference depending on the thermal power plant, it can be understood that the sludge amount and the moisture content are reduced in any of the samples A and B as compared with the comparative example. Accordingly, it can be said that the sludge can be slurried by heating the sludge at a temperature of 80 ° C. or higher and 210 ° C. or lower in the heating unit 70, and then the amount of sludge can be reduced by performing dehydration by the dehydration unit 90.

  Here, from the viewpoint of reducing the amount of energy required for heating, it can be said that the slurrying temperature is preferably in the range of 80 ° C. or higher and 130 ° C. or lower. In addition, when comparing sample A2 and sample A3 and comparing sample B2 and sample B3, there is no difference in the amount of sludge and moisture content as much as the difference in treatment conditions. Then, if it restrict | limits to this condition, it can be said that the temperature of slurrying is 130 degreeC most preferable.

<Summary>
As described above, according to the present embodiment, when the inner pipe 71 is heated by the heating steam, the sludge moving in the moving space 71a is heated and slurried by a hydrothermal reaction. Thus, since sludge can be slurried in the process of moving the moving space 71a of the inner pipe 71, continuous processing is possible. As a result, sludge can be efficiently dehydrated. Moreover, the sludge heating degree can be defined by the length of the inner pipe 71 and the outer pipe 72 and the moving speed of the sludge, and the pressure at the time of slurrying can be defined by the amount of sludge and the size of the moving space 71a. For this reason, the conditions for slurrying can be determined with a simple configuration.

=== Second Embodiment ===
Next, a second embodiment will be described. As shown in FIG. 5, the second embodiment is characterized in that a pre-dehydration unit 100 is provided between the sludge concentration unit 60 and the heating unit 70. The pre-dehydrating unit 100 is a part that dehydrates the sludge concentrated in the sludge concentrating unit 60 before supplying it to the heating unit 70. That is, the sludge dehydrated by the pre-dehydration unit 100 is supplied to the heating unit 70. The pre-dehydrating unit 100 uses devices using various methods, like the dehydrating unit 90 of the first embodiment.

  In the present embodiment, the belt press type pressure dehydrating apparatus 101 and the hopper 102 are provided as in the dewatering unit 90. The sludge (dehydrated cake) dehydrated by the dehydrator 101 is sent to the hopper 102 and sent to the heating unit 70 by the pump 103. In addition, since parts other than the pre-dehydration part 100, such as the heating part 70 and the cooling part 80, are the same as 1st Embodiment, description is abbreviate | omitted.

  FIG. 6 shows the amount of sludge and the water content when the sludge from the sludge concentrating unit 60 is treated by the dehydration facility of the second embodiment. Samples A1 to A3 and samples B1 to B3 are the same as those in the first embodiment. Further, the left side of the arrow is a comparative example, which is the same as in the first embodiment.

Regarding samples A1 to A3, the amount of sludge in the comparative example was 111 m ³ , whereas the amount of sludge in sample A1 (80 ° C.) was 80 m ³ , and the amount of sludge in sample A 2 (130 ° C.) was 67 m ³ . Yes, the amount of sludge of sample A3 (210 ° C.) was 57 m ³ . Regarding the moisture content, the moisture content in the comparative example was 82%, whereas the moisture content of sample A1 was 75%, the moisture content of sample A2 was 70%, and the moisture content of sample A3 was 65%.

Relates samples B1 to B3, the amount of sludge in the comparative example while which was a 95 m ^3, the amount of sludge in the sample B1 (80 ° C.) is 87m ^3, sludge amount of sample B2 (130 ° C.) is 65 m ³ Yes, the amount of sludge of sample B3 (210 ° C.) was 53 m ³ . Regarding the moisture content, the moisture content in the comparative example was 79%, whereas the moisture content of sample B1 was 77%, the moisture content of sample B2 was 69%, and the moisture content of sample A3 was 62%.

  As in the first embodiment, it was confirmed that the sludge amount and the water content can be reduced as compared with the comparative example also in the second embodiment. In the second embodiment, since the sludge pre-dehydrated by the pre-dehydration unit 100 is slurried, the sludge can be heated efficiently by the amount of water, and the energy required for the slurry can be suppressed.

=== Third Embodiment ===
Next, a third embodiment will be described. This third embodiment is characterized in that a plurality of outer pipes are provided in a state in which they are arranged in the extending direction of the inner pipe. 7A to 7D show an example in which three outer pipes 72A to 72C are arranged. For convenience, the outermost pipe on the most upstream side in the traveling direction of the sludge is referred to as a first outer pipe 72A, and the outermost downstream pipe is referred to as a third outer pipe 72C. Further, the outer pipe located between the first outer pipe 72A and the third outer pipe 72C is referred to as a second outer pipe 72B.

  Cylindrical portions 72b and 72c (see FIG. 3) serving as inlets and outlets for heating steam are provided at both ends of the first outer pipe 72A to the third outer pipe 72C, and these cylindrical parts 72b. , 72c according to the connection mode, the overheated state of the sludge moving through the inner pipe 71 can be adjusted.

  In FIG. 7A, the downstream cylindrical portion of the third outer pipe 72C is used as the heating steam inlet, and the upstream cylindrical section of the first outer pipe 72A is used as the heating steam outlet. The upstream cylindrical portion of the third outer pipe 72C is connected to the downstream cylindrical portion of the second outer pipe 72B, and the upstream cylindrical portion of the second outer pipe 72B is connected to the downstream cylinder of the first outer pipe 72A. Is connected to the section. Thereby, a series of steam flow paths are formed from the third outer pipe 72C through the second outer pipe 72B to the first outer pipe 72A. In this example, the sludge heating temperature can be increased from the upstream side of the first outer pipe 72A toward the downstream side of the third outer pipe 72C.

  In FIG. 7B, the downstream cylindrical portion of the second outer pipe 72B is used as the first inlet, and the upstream cylindrical section of the third outer pipe 72C is used as the second inlet. Further, the upstream cylindrical portion of the first outer pipe 72A is used as the first outlet, and the downstream cylindrical section of the third outer pipe 72C is used as the second outlet. And the downstream cylindrical part of 72 A of 1st outer side piping is connected to the upstream cylindrical part of 72 B of 2nd outer side piping. As a result, a first heating steam flow path that flows through the first outer pipe 72A and the second outer pipe 72B, and a series of steams from the third outer pipe 72C through the second outer pipe 72B to the first outer pipe 72A. A flow path is formed. In this example, the sludge heating temperature can be increased from the upstream side of the first outer pipe 72A toward the downstream side of the second outer pipe 72B. Moreover, about the 3rd outer side piping 72C, heating temperature can be defined independently and heating temperature can be lowered | hung toward a downstream side.

  FIG. 7C shows the downstream side cylinder of the third outer pipe 72C with the downstream side cylindrical part of the first outer side pipe 72A as the first inlet and the downstream side cylindrical part of the second outer side pipe 72B as the second inlet. The section is used as the third inlet. Similarly, the upstream cylindrical portion of the first outer pipe 72A is the first outlet, the upstream cylindrical portion of the second outer pipe 72B is the second outlet, and the upstream cylindrical portion of the third outer pipe 72C is the first outlet. Used as 3 outlets. In this example, the heating temperature can be determined individually for each outer pipe.

  As can be seen from the above description, in the third embodiment, the manner of heating the sludge can be changed by the connection of the steam pipes to the outer pipes 72A to 72C. Thereby, the temperature conditions at the time of slurrying sludge can be optimized.

=== Other Embodiments ===
The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention is changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  For example, the sludge to which the present invention is applied is not limited to that discharged from the wastewater treatment facility of FIG. Even if it is discharged from another form of wastewater treatment facility, it can be applied in the same manner.

  An electric heater may be used as the heating mechanism. In this case, after the electric heater is wound around the outer periphery of the inner pipe 71, the outer peripheral surface of the electric heater may be covered with a heat insulating material.

10 NS decomposition section, 11 NS decomposition tank, 12 water storage tank, 13 pump, 20 fluorine treatment section, 21 fluorine treatment tank, 22 first precipitation tank, 30 nitrogen treatment section, 31 first relay tank, 32 nitrogen treatment tank, 32a Aerobic bacteria treatment chamber, 32b Anaerobic bacteria treatment chamber, 32c Nitrogen discharge chamber, 33 Second sedimentation tank, 34 Pump, 40 Heavy metal treatment section, 41 Second relay tank, 42 Heavy metal treatment tank, 43 Third sedimentation tank, 44 Pump, 50 COD processing section, 51 adjustment tank, 52 sand filtration tower, 53 COD adsorption tower, 54 neutralization tank, 55 pump, 60 sludge concentration section, 61 precipitation tank for concentration, 62 pump, 70 heating section, 71 inner piping , 71a moving space, 72 outer piping, 72A first outer piping, 72B second outer piping, 72C third outer piping, 72a heating space, 72b cylindrical shape serving as a steam inlet Part, 72c cylindrical part which becomes steam outlet, 80 cooling part, 81 inner pipe, 82 outer pipe, 90 dehydration part, 91 belt press type pressure dehydration device, 92 pump, 100 pre-dehydration part, 101 belt press type pressurization Dehydrator, 102 hopper, 103 pump

Claims (6)

A concentrating section for concentrating sludge in the wastewater discharged from the thermal power plant,
A slurrying unit that heats and slurries the sludge concentrated in the concentration unit;
A sludge dewatering system comprising a dewatering unit for dewatering the sludge slurried,
The slurrying part is
A heat transfer pipe having heat transfer properties;
A heating mechanism for heating the heat transfer pipe from the outside,
The sludge dewatering system, wherein the inside of the heat transfer pipe is a moving space in which the sludge moves.   The sludge dewatering system according to claim 1, further comprising a pre-dewatering unit that dewaters the sludge concentrated in the concentration unit and supplies the sludge after dewatering to the slurrying unit. The heating mechanism is
Heating to heat the heat transfer pipe from the outside by dividing the space into which the heat transfer pipe is inserted into the inside and introducing a heating steam into a heating space formed between the heat transfer pipe and the inserted heat transfer pipe The sludge dewatering system according to claim 1 or 2, characterized by comprising a pipe. The heating pipe is
The sludge dewatering system according to claim 3, wherein the sludge dewatering system is provided with a plurality of inlets and outlets for the heating steam and arranged in an extending direction of the heat transfer pipe. The heating mechanism is
The sludge dewatering system according to claim 3 or 4, wherein the heating steam adjusted so that a temperature of the sludge in the moving space is 210 ° C or lower and 80 ° C or higher is introduced into the heating space. . The heating mechanism is
The heating steam adjusted so that the temperature of the sludge in the moving space is 130 ° C. or lower and 80 ° C. or higher is introduced into the heating space. The described sludge dewatering system.

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