JP2015020141A - Sludge dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge dryer that prevents sludge during drying on a belt from solidifying and becoming immobile even in sludge drying for various water content condition at the outlet.SOLUTION: A drying part 51 constituting a sludge dryer 100 includes first-third belt conveyors (16, 17, 18) arranged each with a space in the vertical direction. A first cracking machine 8 is installed at the conveying-direction downstream end of the first belt conveyor 16, while a second cracking machine 9 is installed at the conveying-direction downstream end of the second belt conveyor 17. The operation conditions of the first cracking machine 8 and the second cracking machine 9 are changed by a cracking machine controller 23 according to dry conditions of dewatered sludge.

Description

  The present invention relates to a sludge dryer and a sludge drying method for drying dewatered sludge and the like generated in the process of treating sewage.

  Regarding this type of technology, for example, there is one described in Patent Document 1. The string-shaped modeling drying apparatus described in Patent Document 1 is a sludge dryer of a type in which sludge dropped on a mesh belt is dried by ventilation with a ventilation fan, and the sludge is dried while the sludge is conveyed by a belt conveyor. . By shaping sludge into a string shape by rotation of the shaping compression roller and dropping it on the mesh belt to form a cross-girder shape, it is easy to move the moisture when drying the sludge by ventilation from the ventilation fan, It facilitates ventilation. Thereby, it is called in patent document 1 that sludge can be dried at low temperature.

JP 2008-20172 A

  Here, in the string-shaped modeling and drying apparatus described in Patent Document 1, an inverted guide plate with a vibrator is disposed at the downstream end portion in the transport direction of the belt conveyor. This inside-out guide plate is intended to turn the string-like sludge accumulated in a plurality of stages without losing its accumulated state.

  Here, when dewatered sludge generated in the process of treating sewage is targeted for drying treatment, the moisture content of the dewatered sludge charged into the sludge dryer is often constant at about 80 wt%, for example. The target moisture content (exit moisture content) of sludge varies depending on the purpose of the drying treatment. When the dehydrated sludge is dried as a pretreatment for sludge incineration, the dehydrated sludge is dried so as to have a moisture content of 78 wt%, for example. When sludge is turned into a solid fuel, the dehydrated sludge is dried so as to have a moisture content of 10 wt%, for example. Moreover, according to a customer's request, for example, the dewatered sludge may be dried so as to have a desired moisture content in a range of 30 to 60 wt%.

  The belt conveyor type sludge dryer has the following problems to be improved. The sludge in the middle of drying on the belt (for example, sludge formed in a string shape as described in Patent Document 1) is solidified, and the sludge that is lumped is transported on the belt, and the side wall of the housing that houses the belt conveyor May collide with each other and stop moving (sludge is fixed on the belt).

  According to the inside-out guide plate with a vibrator described in Patent Document 1, it is possible to prevent sludge from being fixed on the belt to some extent (collision with the inside-out guide plate and becoming unmovable as it is). However, when the target moisture content (exit moisture content) of dry sludge varies, the sludge of all target moisture contents (exit moisture content) can be obtained by means such as the inside-out guide plate with a vibrator described in Patent Document 1. On the other hand, it is difficult to effectively prevent sludge during drying from being fixed on the belt.

  The present invention has been made in view of the above circumstances, and the problem to be solved is that sludge on the belt is solidified and does not move even in sludge drying treatment under various outlet moisture content conditions. It is providing the sludge dryer which can prevent.

  The present invention is a sludge dryer for drying dehydrated sludge, the drying unit for drying the sludge while supplying dry air to the drying unit for the sludge and the drying unit. A dry air generating unit that returns air as moist air, and the drying processing unit is housed in the housing, and the first belt conveyor that is dried while transporting the sludge, A second belt conveyor that is housed in the housing, is installed below the first belt conveyor, and is dried while transporting the sludge that has fallen from the first belt conveyor; A first crusher that is installed at the downstream end of the first belt conveyor in the conveyance direction and is rotatively driven to crush the sludge, and is housed in the housing and downstream in the conveyance direction of the second belt conveyor. Set on the side edge And a second crusher that crushes the sludge by being rotationally driven, and changes the operating conditions of the first crusher and the second crusher according to the dry state of the sludge. This is a sludge dryer.

  The present invention is also a method invention. That is, the present invention is a sludge drying method for drying dehydrated sludge, wherein the sludge is disposed in a drying treatment section including a plurality of belt conveyors accommodated in a casing and arranged at intervals in the vertical direction. And a drying process for supplying the drying air to the drying processing unit and drying the sludge while transporting the sludge by the plurality of belt conveyors. It is a sludge drying method characterized by having the sludge crushing process which crushes the said sludge conveyed to the conveyance direction downstream end part of the at least 1 or more belt conveyor according to the dry state of the said sludge.

  According to the present invention, it is possible to prevent sludge during drying on the belt from solidifying and becoming unable to move even in sludge drying treatment under various outlet moisture content conditions.

It is a schematic diagram which shows the sludge dryer which concerns on one Embodiment of this invention. It is the figure which expanded the upper part of the drying process part shown in FIG. It is a figure which shows the perforated plate of the dewatering sludge molding machine shown in FIG. It is a perspective view which shows the mode of the dehydrated sludge which falls and conveys on the belt of the upper stage of a drying process part.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, dewatered sludge (organic sludge) generated in the process of treating sewage is targeted for low-temperature drying treatment, but the sludge dryer according to the present invention can also be applied to inorganic sludge. In addition, the moisture content of the sludge (dehydration sludge) before a process is about 78 wt%-82 wt%, for example.

  A sludge dryer 100 according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the sludge dryer 100 of the present embodiment is a packaged sludge dryer, which includes a dry air generation unit 50 and a drying processing unit 51, and constitutes the dry air generation unit 50. Devices (not shown) and devices such as the belt conveyors 16, 17, and 18 constituting the drying processing unit 51 are accommodated in one housing 30. The dry air generation unit 50 and the drying processing unit 51 are partitioned by a partition plate 30b (side wall). Note that the dry air generation unit 50 and the drying processing unit 51 may not be accommodated in one housing 30. For example, the dry air generating unit 50 and the drying processing unit 51 may be separately housed in different housings. Furthermore, the devices constituting the dry air generation unit 50 do not have to be put in the cover (housing).

(Dry air generator)
The dry air generating unit 50 dehumidifies and raises the temperature of, for example, 20 ° C. to 40 ° C. wet air that has returned from the inside of the drying processing unit 51, and removes dehumidified air (dry air) at, for example, 30 ° C. It is a device for blowing air.

  The dry air from the dry air generating unit 50 is supplied to the lower part of the housing 30 and below the third belt conveyor 18. In addition, the air that has been used to dry the dewatered sludge and becomes moist air returns to the dry air generation unit 50 from above the first belt conveyor 16 in the upper part of the housing 30. The dry air supplied into the housing 30 rises through the housing 30 while passing through the belts (18a, 17a, 16a), returns to the dry air generation unit 50 as moist air. In addition, the supply position of the dry air into the drying processing unit 51 and the extraction position of the humid air from the drying processing unit 51 are not limited to those in the present embodiment.

(Dry processing part)
The drying processing unit 51 is a device for drying the dehydrated sludge by applying the dry air supplied from the dry air generating unit 50 to the dehydrated sludge supplied from the outside. The drying processing unit 51 includes a dewatered sludge molding machine 1, a first belt conveyor 16, a second belt conveyor 17, and a third belt conveyor 18 in order from the side to which dehydrated sludge is supplied.

(Dehydrated sludge molding machine)
First, the dewatered sludge molding machine 1 will be described with reference to FIGS. 2 and 3. FIG.2 (b) is an AA arrow line view of Fig.2 (a). The dewatered sludge molding machine 1 includes a main body case 2 and a perforated plate 3.

<Body case>
As shown in FIG. 2, the main body case 2 is an isosceles triangular container whose longitudinal section (internal space) extends downward, and the two side plates 4 arranged so as to expand downward. And two side plates 5 in the shape of an isosceles triangle arranged in the vertical direction. A supply port 2a into which dehydrated sludge is press-fitted is provided at a portion located at the apex angle of the isosceles triangle. The part located at the base of the isosceles triangle is an opening 2b, and the perforated plate 3 is attached to this part. A flange 22 is attached to the supply port 2a. The sludge pipe 20 is connected to the supply port 2 a of the main body case 2 through the flange 22, and dehydrated sludge is press-fitted into the main body case 2 from, for example, a rotary volume type single-shaft eccentric screw pump P.

  Baffle plates 6 are attached to the inner surfaces of the two side plates 5, respectively. The baffle plate 6 is a rectangular plate for dispersing the dewatered sludge supplied into the main body case 2. When the flow of the dewatered sludge in the main body case 2 is biased, the flow of the dehydrated sludge can be adjusted to be uniform by attaching the baffle plate 6. The shape of the baffle plate 6 is not limited to a quadrangle. The baffle plate 6 may be attached to only one of the two side plates 5. Further, the baffle plate 6 is an adjustment plate when the flow of dewatered sludge in the main body case 2 is biased, and is not necessarily required.

  As in the present embodiment, by forming the main body case 2 so that the vertical cross section (internal space) of the main body case 2 has an isosceles triangle shape extending downward, dewatered sludge to every corner in the main body case 2 As a result, the dewatered sludge formed in a string shape can be evenly pushed out from the perforated plate 3. The vertical cross-section (internal space) of the main body case 2 has an isosceles triangle shape and the supply port 2a is provided at the apex angle to diffuse dewatered sludge to every corner of the main body case 2. Although it is a preferable configuration that is easy to fill, it is not always necessary to have an isosceles triangle shape. By forming the main body case so that the internal space expands from the upper part toward the lower part, it is possible to improve the diffusibility and fullness of the dewatered sludge.

<Perforated plate>
As shown in FIG. 3, the perforated plate 3 is a plate in which a plurality of holes 7 are formed. From this perforated plate 3, dewatered sludge becomes a string and is pushed downward and falls. The perforated plate 3 is fixed to the main body case 2 with screws, and is easily attached to and detached from the main body case 2.

  In the isosceles triangular main body case 2 of the present embodiment, the pressure at the center of the perforated plate 3 (pressure due to press-fitted dewatered sludge) is higher than the pressure at the end of the perforated plate 3. Therefore, the number of holes 7 at the end portion of the porous plate 3 is made larger than the number of holes 7 at the center of the porous plate 3. Thereby, the perforated plate portion in which the dewatered sludge is hardly pushed out by the wall surface resistance in the perforated plate 3 part is reduced. As a result, the dewatered sludge can be evenly extruded from the perforated plate 3.

  In the present embodiment, the diameters of the holes 7 are all the same, and the number of holes 7 is changed between the central portion and both end portions. However, both end portions are changed without changing the number of holes 7 between the central portion and both end portions. The diameter of the hole 7 may be larger than the diameter of the hole 7 in the central portion. That is, the aperture ratio of the low pressure portion (both end portions) received by the porous plate 3 may be larger than the aperture ratio of the high pressure portion (center portion).

  Further, in the present embodiment, the holes 7 are arranged alternately at both the central portion and both end portions of the perforated plate 3. By doing so, the string-like dewatered sludge pushed out from the hole 7 is not easily caught. In addition, the shape of the hole provided in the porous plate 3 does not need to be a perfect circle. An ellipse may be sufficient and polygons, such as a triangle and a rectangle, may be sufficient.

  The diameter of the hole 7 formed in the porous plate 3 is preferably 5 mm or more and 20 mm or less. Since the diameter of the hole 7 formed in the perforated plate 3 is 5 mm or more, the hole 7 can be prevented from being blocked by foreign matters (hair etc.). Moreover, if the diameter of the dewatered sludge formed in a string shape is too large, it is difficult to dry to the vicinity of the center. Since the diameter of the hole 7 is 20 mm or less, a string-like dewatered sludge that can be easily dried to the vicinity of the center can be formed.

(First belt conveyor)
Next, the first belt conveyor 16 will be described with reference to FIGS. 1 and 2. The first belt conveyor 16 is a belt-type conveyor that dries the dewatered sludge that has fallen from the dewatered sludge molding machine 1 while transporting it. As shown in FIG. 1, the first belt conveyor 16 is disposed in the upper part of the housing 30 and below the dewatered sludge molding machine 1. The first belt conveyor 16 includes a driving roller 16b, a driven roller 16c, and an endless belt 16a stretched over the driving roller 16b and the driven roller 16c. The drive roller 16b is rotationally driven by, for example, an electric motor. The belt 16a is formed with a number of slits (holes) large enough to prevent dewatered sludge from falling so that air can easily pass therethrough (the same applies to the belts 17a and 18a described later). In order to prevent the dry air (air) used for drying the dewatered sludge from short circuiting without passing through the belt 16a, for example, the width of the belt 16a is the inner dimension (belt 16a) in the housing 30. The length from one end to the other end in the casing 30 in the width direction of the casing 30 is substantially equal), and the driven roller 16c is disposed near the side wall 30b (partition plate) of the casing 30.

<First crusher>
A first crusher 8 for crushing dewatered sludge is installed at the downstream end of the first belt conveyor 16 in the conveying direction. “Crushing” means loosening and breaking up a collection of fine particles. The first crusher 8 installed in the vicinity of the drive roller 16b includes, for example, a rod-shaped body 8a that is rotationally driven by an electric motor, and a plurality of flat-shaped crushing members 8b ( Blade). The bending direction of the crushing member 8b bent like a bow is opposite to the rotating direction of the rod-shaped body 8a. Further, the length of the rod-like body 8a is substantially equal to the width of the belt 16a. That is, the dewatered sludge can be crushed over the entire width direction of the belt 16a. A plurality of crushing members 8b are provided at predetermined intervals in the longitudinal direction of the rod-shaped body 8a. In addition, the shape of the crushing member 8b is not restricted to the shape of this embodiment.

  It is possible to suppress dewatered sludge from being caught on the blade of the crusher by making the blade of the crusher into a bow and turning the crusher rotation direction and the curved direction of the bow into opposite directions.

(Sensor)
A sensor 26 (level sensor such as an infrared sensor) is provided slightly upstream from the first crusher 8 (specifically, the rod-shaped body 8a). The sensor 26 is for detecting the dry state (the lump state) of the dewatered sludge on the first belt conveyor 16 (the dewatered sludge conveyed on the first belt conveyor 16). The sensor 26 is attached in such a direction as to detect what is below the vertical direction.

Here, when the sensor 26 is viewed from above (vertically above) the drying processing unit 51 (in a plan view), the sensor 26 is connected to the driving roller 16b (and the belt 16a) and the rod-like body 8a of the first crusher 8. It is located at a position that does not overlap with the rotating crushing member 8b and that does not detect the sludge falling from the belt 16a without hitting the rod-like body 8a. That is, the sensor 26 is a position where the sludge that does not hit the belt 16a, the first crusher 8, and the first crusher 8 (specifically, the rod-like body 8a) and does not detect the sludge is dropped. It arrange | positions in the position which detects the sludge accumulated between the crushers 8 (it is the same also when installing the sensor 26 slightly upstream from the 2nd crusher 9).
When the belt 16a and the first crusher 8 are sufficiently separated from each other, the sensor 26 is a space between the driving roller 16b (and the belt 16a) and the crushing member 8b of the first crusher 8. You may arrange | position so that it may detect.

  In order to detect the dry state of the dewatered sludge on the second belt conveyor 17, the sensor 26 may be installed slightly above the second crusher 9.

Further, as a sensor for detecting the dry state of the dewatered sludge on the belt conveyor, a pressure sensor may be used instead of the level sensor. For example, when the accumulation state of dewatered sludge between the first belt conveyor 16 and the first crusher 8 is detected by the pressure increase in the drying processing unit 51, the space above the first belt conveyor 16 and the first belt A pressure sensor is installed in each of the spaces between the conveyor 16 and the second belt conveyor 17. The dry state of the dewatered sludge can be detected by measuring the pressure difference between these sensors. Specifically, when the sludge is dried on the belt 16a, depending on the dry state, the sludge does not fall down at the end of the belt 16a, and the shape on which the sludge rides on the belt 16a is maintained and reaches the side wall 30a. Moved. On the other hand, air is always supplied to the apparatus for drying sludge, and a portion of the passage (air passage) is blocked by the sludge, so that the upper space and the lower space of the belt conveyor 16 Will cause a difference in pressure. The sludge accumulation state can be confirmed by detecting this differential pressure with a pressure sensor.
A moisture meter may be used as a sensor for detecting the dry state of the dewatered sludge on the belt conveyor. For example, the dry state of the dewatered sludge can be measured by measuring the moisture content of the sludge moving on the belt conveyor on which the crusher is installed. Specifically, as the moisture meter, a general non-contact moisture meter can be used, and a moisture meter using infrared rays or microwaves can be used. The dehydrated sludge on the belt is measured with these moisture content meters. The measurement position is not particularly limited, but measurement is preferably performed on the rear side of the belt center, and more preferably in the vicinity of the belt end near the crusher.
On the other hand, sensors such as a level sensor and a pressure sensor are not essential.

(Second belt conveyor)
The second belt conveyor 17 is a belt-type conveyor that dries while drying the dewatered sludge that has fallen from the first belt conveyor 16, and is installed below the first belt conveyor 16. Similar to the first belt conveyor 16, the second belt conveyor 17 is, for example, a driving roller 17b that is rotationally driven by an electric motor, a driven roller 17c, and an endless belt that is stretched over the driving roller 17b and the driven roller 17c. 17a. Further, in order to prevent the dry air (air) used for drying the dewatered sludge from being short-circuited without passing through the belt 17a, for example, the width dimension of the belt 17a is the inner dimension (belt 17a) in the housing 30. The length from one end to the other end in the housing 30 in the width direction of the housing 30 is substantially equal to the other end), and the driven roller 17c is disposed near the side wall 30a of the housing 30. The direction of transporting the dewatered sludge by the second belt conveyor 17 is opposite to the direction of transporting the dewatered sludge by the first belt conveyor 16.

<Second crusher>
A second crusher 9 for crushing dewatered sludge is installed at the downstream end of the second belt conveyor 17 in the conveying direction. The configuration of the second crusher 9 and the shape, dimensions, arrangement, and the like of each component are the same as those of the first crusher 8 described above.

(Crusher control device)
A crusher control device 23 is attached to the outer surface of the housing 30. In addition, the attachment position of the crusher control apparatus 23 is not restricted to this.

  The crusher control device 23 is for changing the operating conditions of the first crusher 8 and the second crusher 9 according to the dry state of the dewatered sludge. The phrase “according to the drying state of the dewatered sludge” means, for example, according to the solid state of sludge (for example, sludge formed in a string shape) in the middle of drying on the belt of the belt conveyor. This means, for example, according to the target moisture content of the dewatered sludge (the moisture content at the outlet of the sludge dryer). As a method for changing the operating conditions of the first crusher 8 and the second crusher 9, there are the following changing methods.

  As described above, the moisture content of the dewatered sludge introduced into the sludge dryer 100 is often constant, for example, about 80 wt%, but the target moisture content (exit moisture content) of the dried sludge is the purpose of the drying process. It depends on. When the dehydrated sludge is dried as a pretreatment for sludge incineration, the dehydrated sludge is dried so as to have a moisture content of 78 wt%, for example. When sludge is turned into a solid fuel, the dehydrated sludge is dried so as to have a moisture content of 10 wt%, for example. Moreover, according to a customer's request, a dehydration sludge may be dried so that it may become a desired moisture content in the range of moisture content: 30-60 wt%. The moisture content is adjusted by adjusting the amount of dewatered sludge charged into the sludge dryer 100, the belt running speed of the belt conveyor, and the like.

  Here, when the target moisture content (exit moisture content) is as high as 78 wt%, for example, sludge during drying on the belt is unlikely to solidify on the belt. And the 2nd crusher 9 does not need to drive | operate. On the other hand, when the target moisture content (exit moisture content) is as low as 10 wt%, for example, sludge during drying on the upper belt 16a may frequently solidify on the belt 16a. For example, the first crusher 8 is operated and the second crusher 9 is stopped. When the target moisture content (exit moisture content) is between 78 wt% and 10 wt%, such as 30 to 60 wt%, the drying is not performed on the upper belt 16a but on the lower belt 17a. Since sludge may harden, for example, the first crusher 8 is stopped and the second crusher 9 is operated. This is summarized in the following table. Note that this operating condition is merely an example.

  Here, in addition to changing the operating conditions of the crusher according to the target moisture content (exit moisture content) of the sludge, the operating condition of the crusher according to the sludge accumulation state between the belt conveyor and the crusher It is also preferable to change (operation or stop).

  The crusher control device 23 of the present embodiment is configured to change the operating state of the first crusher 8 based on a signal from the sensor 26. When sludge accumulates between the first belt conveyor 16 and the first crusher 8, the sensor 26 detects this and the crusher control device 23 that has received a signal from the sensor 26 stops the first crusher 8. Change from state to operating state. When the solidified sludge is crushed by the rotation of the first crusher 8 and the sludge is no longer accumulated, the crusher control device 23 receiving the signal from the sensor 26 stops the first crusher 8 from the operating state. To.

(3rd belt conveyor)
The third belt conveyor 18 is a belt-type conveyor that dries the dewatered sludge that has fallen from the second belt conveyor 17 and is installed below the second belt conveyor 17. As with the first belt conveyor 16, the third belt conveyor 18 is, for example, a driving roller 18b that is rotationally driven by an electric motor, a driven roller 18c, and an endless belt that is stretched around the driving roller 18b and the driven roller 18c. 18a. Further, in order to prevent dry air (air) used for drying dehydrated sludge from short-circuiting without passing through the belt 18a, for example, the width of the belt 18a is set to the inner dimension (belt 18a) in the housing 30. The length from one end to the other end in the casing 30 in the width direction of the casing 30 is substantially equal to the other end), and the driven roller 18 c is disposed near the side wall 30 b of the casing 30. In addition, the conveyance direction of the dewatered sludge by the 3rd belt conveyor 18 is the same direction as the conveyance direction of the dewatered sludge by the 1st belt conveyor 16.

  In the present embodiment, three belt conveyors are provided in total. However, four or more belt conveyors may be arranged in the housing 30 at intervals in the vertical (vertical) direction.

(Drying principle)
The dewatered sludge press-fitted into the dewatered sludge molding machine 1 of the drying processing unit 51 falls in a string shape and is conveyed on the belt 16a of the first belt conveyor 16. The dewatered sludge conveyed to the downstream end of the first belt conveyor 16 falls onto the belt 17a of the second belt conveyor 17 and is further conveyed. The dewatered sludge conveyed to the downstream end of the second belt conveyor 17 falls onto the belt 18a of the third belt conveyor 18 and is further conveyed. When the dewatered sludge is conveyed on the belts 16a, 17a, and 18a, the dehydrated sludge is dried by contacting with dehumidified air of 30 ° C or higher (for example, 30 to 60 ° C) from the dry air generating unit 50. The dried sludge is discharged from the sludge discharge port 19.

  The dehumidified air of 30 ° C. or higher sent from the dry air generation unit 50 to the drying processing unit 51 by a blower fan (not shown) takes in moisture of the dehydrated sludge and becomes humid air. The humid air that has returned to the dry air generator 50 is cooled by the cooler 12, and the moisture in the humid air is condensed and removed. The dehumidified air from which moisture has been removed is heated by the heater 11 and becomes dehumidified air of 30 ° C. or higher again. The humid air is cooled (dehumidified) and heated by heat exchange with the refrigerant.

(Action / Effect)

Here, depending on the target moisture content of the dried sludge, the sludge on the belt is solidified, and the sludge that has become a lump is transported on the belt and collides with the side wall of the housing that houses the belt conveyor, and the like. It may stop moving (sludge is fixed on the belt). However, according to the present invention, the operation conditions of the first crusher 8 and the second crusher 9 are changed in accordance with the dry state of the dewatered sludge, so that it is transported to the downstream end in the transport direction of the belt conveyor. The solidified sludge is crushed by the crusher, and the sludge fixation on the belt is released. In other words, according to the present invention, sludge drying on the belt can be prevented from solidifying and not moving even in the sludge drying process under various outlet moisture content conditions.
In addition, there is an effect that a new dry surface (surface exposed to air) of sludge is formed by crushing by a crusher. Thereby, the drying efficiency of sludge improves.

  Here, when the dry state of the dewatered sludge is low, the dewatered sludge moving on the belt is soft, so it falls by its own weight at the end of the belt, and even if it is cut by the crusher, it will be joined again on the lower belt. Therefore, the cutting action by the crusher is low and the crusher is meaningless. Furthermore, when such sludge adheres to the crusher, it is dried on the crusher, and further, the sludge clumps and grows, so that the crusher itself becomes an obstacle and it is necessary to stop the drier itself. In contrast, in the present invention, by installing a crusher with a space from the downstream end in the conveying direction of the belt conveyor to the downstream side in the horizontal direction, when the dewatered sludge falls by its own weight, the crusher is used as it is (running) ) When the dewatered sludge has been dried and part of the dehydrated sludge has become dry (when solidified), the sludge is dried while being prevented from adhering to the crusher by cutting with a crusher. Can do.

  In addition, by providing a sensor for detecting the dry state (lump state) of the sludge on the belt conveyor, the operation state of the crusher can be changed based on the signal from this sensor, It can prevent more reliably that the sludge in the middle of drying becomes hard and does not move.

  The effects of installing the crusher at the downstream end of the belt conveyor in the transport direction include the following. By crushing the solidified sludge by the crusher, the inner part of the sludge that has not been exposed to air comes to be exposed to air, and the wetness of the humid air returning to the dry air generating part is increased. That is, the sludge drying efficiency is improved.

  In addition, each belt conveyor (16, 17, 18) is arranged at intervals in the vertical (vertical) direction, and is configured such that sludge falls from the upper belt conveyor to the lower belt conveyor, When falling from the conveyor, the sludge drying surface (surface exposed to air) is replaced, and the sludge drying efficiency is further improved.

  Furthermore, by arranging three or more belts (three or more belt conveyors spaced apart in the vertical direction), sludge and dehumidified air (dry air) are compared to the case of two or less belts. Contact time increases, and the drying efficiency of sludge is further improved.

  Moreover, in this embodiment, the dry air from the dry air generation part 50 is supplied to the lower part of the housing | casing 30, and the downward direction of the 3rd belt conveyor 18 located in the lowest step. In addition, the air that has been used to dry the dewatered sludge and becomes humid air returns to the dry air generation unit 50 from above the first belt conveyor 16 located in the uppermost part of the housing 30. ing. By being configured in this way, the dry air supplied into the casing 30 rises in the casing 30 while passing through all the belts (18a, 17a, 16a), so that the drying efficiency of sludge is further increased. improves.

  Further, in the present embodiment, the dewatered sludge is extruded in a string form from the perforated plate 3 of the dewatered sludge molding machine 1 and falls down. At this time, the dewatered sludge formed in a string shape is cut by its own weight. When the dewatered sludge is cut to an appropriate length, the dewatered sludge is uniformly sprayed on the belt 16a of the first belt conveyor 16, and the dewatered sludge is conveyed while being dried on the belt 16a while maintaining a gap. That is, the sludge drying efficiency is improved by the dewatered sludge molding machine 1 as well.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

  For example, the 3rd belt conveyor 18 which does not attach a crusher to the downstream end part of a conveyance direction may be arrange | positioned between the 1st belt conveyor 16 and the 2nd belt conveyor 17 instead of the 2nd belt conveyor 17 below. Good. In other words, the second crusher is not located at the downstream end of the second belt conveyor 17 in the transport direction but at the downstream end of the third belt conveyor 18 in the transport direction (the vicinity where the dried sludge falls to the sludge discharge port 19). May be installed.

  Moreover, you may further install a 3rd crusher in the conveyance direction downstream end part (near dry sludge to the sludge discharge port 19) of the 3rd belt conveyor 18. FIG.

  In the present embodiment, there are three belt conveyors, but two belt conveyors may be used.

  Here, the third belt conveyor 18 that does not include a crusher at the downstream end portion in the transport direction (drops dehydrated sludge as it is without crushing at the downstream end portion in the transport direction) is below the second belt conveyor 17. However, it is preferable to arrange the first belt conveyor 16 above the first belt conveyor 16. In this case, the transport direction of the dewatered sludge by the third belt conveyor 18 is opposite to the transport direction of the dewatered sludge by the first belt conveyor 16. Further, the dry air from the dry air generation unit 50 is supplied below the second belt conveyor 17, and the humid air that is used to dry the dewatered sludge is the dry air generation unit 50 from above the third belt conveyor 18. Will be returned to.

  When the crusher is operated on wet sludge, the sludge may adhere to and grow on the crusher, and sludge mass may be formed in the crusher. The sludge lump formed in the crusher may become an obstacle to the sludge conveyance, or in the worst case, the sludge lump may be blocked and the operation must be stopped. However, according to the configuration described above, such a problem can be effectively prevented.

  Further, the dewatered sludge molding machine 1 provided in the drying processing unit 51 is not limited to the one in this embodiment. Further, it is not always necessary to form the dewatered sludge before dropping onto the belt conveyor into a string shape through the dewatered sludge through the dewatered sludge molding machine 1 or the like.

1: dewatered sludge molding machine 2: main body case 3: perforated plate 8: first crusher 9: second crusher 16: first belt conveyor 17: second belt conveyor 18: third belt conveyor 23: crusher controller 50: Dry air generating unit 51: Drying processing unit 100: Sludge dryer

Claims (5)

A sludge dryer for drying dewatered sludge,
A drying treatment section of the sludge;
While supplying dry air to the drying processing unit, a dry air generating unit in which the dry air used for drying the sludge returns as moist air, and
With
The drying processing unit
A housing,
A first belt conveyor housed in the housing and drying while conveying the sludge;
A second belt conveyor housed in the housing, installed below the first belt conveyor, and drying while transporting the sludge falling from the first belt conveyor;
A first crusher that is housed in the housing, is installed at a downstream end of the first belt conveyor in the conveying direction, and crushes the sludge by being driven to rotate;
A second crusher that is housed in the housing, is installed at a downstream end in the transport direction of the second belt conveyor, and crushes the sludge by being driven to rotate;
Have
The sludge dryer characterized by changing the operating conditions of the first crusher and the second crusher according to the drying state of the sludge. In the sludge dryer according to claim 1,
The drying processing unit
It is accommodated in the housing and is disposed between the first belt conveyor and the second belt conveyor, above the first belt conveyor, or below the second belt conveyor, and is dried while conveying the sludge. And a third belt conveyor
The dry air is supplied from the dry air generation unit to the lower part in the casing, and the dry air used for drying the sludge becomes wet air and is returned to the dry air generation unit from the upper part in the casing. A sludge dryer characterized by that. In the sludge dryer according to claim 2,
The first belt conveyor is a conveyor that conveys the sludge in one direction,
The second belt conveyor is formed to convey the sludge in a direction opposite to the one direction,
The third belt conveyor is disposed above the first belt conveyor, and is configured to convey the sludge in a direction opposite to the one direction,
The dry air is supplied from the dry air generation unit to the lower side of the second belt conveyor, and the dry air used for drying the sludge becomes moist air to generate the dry air from the upper side of the third belt conveyor. Sludge dryer characterized by being returned to the section. In the sludge dryer in any one of Claims 1-3,
A sensor for detecting the drying state of the sludge on the belt conveyor is provided in the drying processing unit,
The said crusher control apparatus changes the operation state of at least any one of a said 1st crusher and a said 2nd crusher based on the signal from the said sensor, The sludge dryer characterized by the above-mentioned. A sludge drying method for drying dehydrated sludge,
The sludge is supplied to a drying processing unit that includes a plurality of belt conveyors that are accommodated in a housing and arranged at intervals in the vertical direction, and the drying air is supplied to the drying processing unit. Comprising a drying treatment step of drying while conveying the sludge;
The drying treatment step includes
In the plurality of belt conveyors, it has a sludge crushing step of crushing the sludge that has been transported to the downstream end in the transport direction of at least one belt conveyor according to the dry state of the sludge. Sludge drying method.

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