JP6298776B2 - Classification bug filter - Google Patents

Description

  The present invention relates to a classification bag filter installed in a facility for granulating and drying dehydrated sludge to form a solid fuel.

  In recent years, biomass has attracted attention as a new energy source. In particular, most of the organic sludge discharged from sewage treatment factories, food processing factories, paper mills and the like is incinerated or melted and recycled into raw materials for cement and construction materials. Such organic sludge has attracted particular attention because it contains organic matter and has superiority in accumulation and stability. Patent Document 1 discloses a granulation drying system that converts dehydrated sludge such as sewage sludge into a solid fuel. FIG. 5 shows the flow of dried sludge in the granulation drying system. This system includes a granulation process in which dewatered sludge stored in the sludge storage hopper 11 and circulating dry sludge supplied from the recycle hopper 15 are kneaded and granulated with a twin-screw mixer 12, and the granulated sludge is dried into a drum. 13 for drying.

  The dried sludge discharged from the drying drum 13 together with the dried air is separated from the dried air by the bag filter 31 installed at the subsequent stage of the drying drum 13, and conveyed to the vibrating sieve 32 by the dried sludge supply conveyor 17. The transported dried sludge is classified by the vibration sieve 32 and a product having a predetermined particle size is charged into the product supply hopper 16. On the other hand, the product outside the product is charged into the recycling hopper 15 as circulating dried sludge and supplied to the twin-screw mixer 12 by the dried sludge recycling conveyor 18.

  On the other hand, in Patent Document 2, coarse powder having a large particle size is separated by a baffle plate out of dust in a gas flow colliding with a baffle plate and falls directly below a first processing chamber for collecting coarse powder. The fine powder having a small particle size that is stored in the first hopper located below the first processing chamber and sent to the second processing chamber together with the gas flow is collected by a filter in the second processing chamber for collecting fine powder. In addition, a dust collector (bag filter) is disclosed that is housed in a second hopper located below the second processing chamber.

JP-A-4-227463 Japanese Utility Model Publication No. 5-88759

  In the conventional granulation drying system described above, the vibration sieve 32 that divides the dried sludge into the product and the circulating dried sludge screens the entire amount of the dried sludge, so that a large-sized one is necessary, and the equipment cost has to be high. . Further, since the granular sludge discharged from the bag filter 31 and the powder sludge are conveyed to the vibrating screen 32, the dried sludge supply conveyor 17 is closed or the particles stored in the recycling hopper 15 are stored. There was a problem that shelves with body sludge (cross-linking blockage phenomenon) and spontaneous ignition were likely to occur.

  On the other hand, the dust collector described in Patent Document 2 is intended for pre-collection before filtration of coarse dust contained in a gas flow. In the dust collector, in order to reduce the dust load on the filter, the coarse powder having a large particle diameter is previously removed by the baffle plate, and has a classification function according to the particle diameter of the coarse powder. Do not mean. In addition, separation is mainly performed by collision with the baffle plate, and coarse powder also flows into the filtration chamber by an air flow toward the filtration chamber.

  The present invention has been made in view of such circumstances, and reduces the equipment cost for the granulation drying system, and also separates the granular sludge having a predetermined particle size from the dry sludge to ensure the stability of the system. For the purpose.

In order to achieve the above object, according to the first invention, dehydrated sludge and dried sludge A are kneaded with a mixer and granulated, and then dried with a drying drum to obtain dried sludge B. Granules contained in dried sludge B A classification bag filter installed in a granulation drying system that supplies a part of sludge as a product and supplies dry sludge A other than the product to the mixer,
The classification bag filter includes a classification unit for separating granular sludge having a particle size equal to or larger than a set particle size from the dried sludge B discharged from the drying drum together with a dry gas, and a plurality of the collected sludge C that has passed through the classification unit. A collection part provided with a filter ,
The classifying unit includes an ascending chamber in which the drying gas rises and a descending chamber in which the rising drying gas descends, and the granular sludge having a terminal velocity larger than the air velocity of the drying gas in the ascending chamber is in the ascending chamber. Discharged from the outlet provided at the bottom,
The passage cross-sectional area of the dry gas in the ascending chamber is determined based on the terminal velocity of the granular sludge having the set particle diameter .

  In the present invention, the granular sludge having a particle size equal to or larger than the set particle size is separated from the dried sludge B discharged from the drying drum together with the dry gas by the classification bag filter, so that the vibration sieve is not required and the equipment cost can be reduced. In addition, since only the granular sludge separated by the classification bag filter can be conveyed to the recycling hopper by the dry sludge supply conveyor, the dry sludge supply conveyor is not blocked, and shelves and spontaneous ignition do not occur in the recycling hopper.

  In the present invention, a part of the granular sludge separated by the classification bag filter becomes a product, and the remaining granular sludge and the dried sludge C become the dried sludge A.

  If the air flow velocity of the drying gas conveying the dried sludge is smaller than the terminal velocity of the granular sludge, the granular sludge cannot rise in the rising chamber and falls, and is discharged from the discharge port provided at the bottom of the rising chamber. On the other hand, when the air velocity of the dry gas is equal to or higher than the terminal velocity of the granular sludge, the granular sludge is transported together with the dry gas, and is collected by a collection unit installed at the subsequent stage of the classification unit.

The terminal speed of granular sludge depends on the particle size and density of the granular sludge. Therefore, by calculating the terminal velocity of the granular sludge from the set particle size, and setting the air flow velocity of the dry gas based on the terminal velocity, the particle size of the granular sludge that can be conveyed by air flow is limited, and it is equal to or larger than the set particle size. It becomes possible to separate the granular sludge.
Since the air velocity of the dry gas is inversely proportional to the cross-sectional area of the dry gas, the cross-sectional area of the dry gas should be determined so that the air velocity of the dry gas is smaller than the terminal velocity of the granular sludge having the set particle size. Thereby, the granular sludge more than a setting particle size can be isolate | separated.

In the second invention, the dewatered sludge and the dried sludge A are kneaded with a mixer and granulated, and then dried with a drying drum to obtain a dried sludge B. A part of the granular sludge contained in the dried sludge B is obtained. A classification bag filter installed in a granulation drying system that supplies a product and dried sludge A other than the product to the mixer,
The classification bag filter includes a classification unit for separating granular sludge having a particle size equal to or larger than a set particle size from the dried sludge B discharged from the drying drum together with a dry gas, and a plurality of the collected sludge C that has passed through the classification unit. A collection part provided with a filter,
The classifying unit includes an ascending chamber in which the drying gas rises and a descending chamber in which the rising drying gas descends, and the granular sludge having a terminal velocity larger than the air velocity of the drying gas in the ascending chamber is in the ascending chamber. Discharged from the outlet provided at the bottom,
A plurality of divided chambers passage space of the drying gas is divided in a direction perpendicular to the passing direction of the drying gas in the elevated chamber, as characterized Rukoto damper is installed at the lower end of one or more of the divided chamber Yes .

In the present invention , the granular sludge having a particle size equal to or larger than the set particle size is separated by controlling the opening / closing degree of the one or more dampers and adjusting the passage cross-sectional area of the dry gas in the ascending chamber.

In the third aspect of the invention, the dewatered sludge and the dried sludge A are kneaded with a mixer and granulated, and then dried with a drying drum to obtain a dried sludge B. A part of the granular sludge contained in the dried sludge B is obtained. A classification bag filter installed in a granulation drying system that supplies a product and dried sludge A other than the product to the mixer,
The classification bag filter includes a classification unit for separating granular sludge having a particle size equal to or larger than a set particle size from the dried sludge B discharged from the drying drum together with a dry gas, and a plurality of the collected sludge C that has passed through the classification unit. A collection part provided with a filter,
The classifying unit includes an ascending chamber in which the drying gas rises and a descending chamber in which the rising drying gas descends, and the granular sludge having a terminal velocity larger than the air velocity of the drying gas in the ascending chamber is in the ascending chamber. Discharged from the outlet provided at the bottom,
Part of the side wall forming the rising chamber, is characterized that you have to be movable toward the opposing side walls.

In the present invention , by moving a part of the side wall forming the rising chamber toward the opposite side wall, the passage cross-sectional area of the dry gas in the rising chamber is adjusted, and the granular sludge having a particle size equal to or larger than the set particle size is separated. .

Moreover, in the classification bag filter which concerns on 1st-3rd invention, the screw conveyor installed in the lower part of the said collection part may extend to the said classification part.

  In the said structure, when the ratio of the dry sludge C increases rapidly compared with the isolate | separated granular sludge etc., a part of dry sludge C is mixed in the isolate | separated granular sludge via a screw conveyor. Therefore, it is possible to avoid the production line from being stopped.

  In the present invention, the granular sludge having a set particle diameter or more is separated from the dried sludge B discharged from the drying drum together with the dry gas by the classification bag filter, so that the vibration sieve is not necessary and the equipment cost can be reduced. The granular sludge having a predetermined particle size can be separated from the dried sludge to ensure the stability of the system.

It is a flowchart which shows the flow of the dry sludge in a granulation drying system provided with the classification bag filter which concerns on the 1st Embodiment of this invention. (A) is a long side direction sectional view of a classification bag filter concerning a 1st embodiment of the present invention, and (B) is a short side direction sectional view of the classification bag filter. (A) is a long side direction sectional view of a classification bag filter concerning a 2nd embodiment of the present invention, and (B) is a short side direction sectional view of the classification bag filter. (A) is a long side direction sectional view of the classification bag filter concerning the 3rd embodiment of the present invention, and (B) is a short side direction sectional view of the classification bag filter. It is a flowchart which shows the flow of the dry sludge in the conventional granulation drying system.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

[Classifying bug filter according to the first embodiment]
FIG. 1 shows a flow of dried sludge in the granulation drying system 10 including the classification bag filter 14 according to the first embodiment of the present invention.
The granulation drying system 10 is a facility for converting dehydrated sludge such as organic sludge into a solid fuel as a spherical granulated dry matter (dry pellet).

In the granulation drying system 10, the dry sludge C discharged from the collection unit 21 of the classification bag filter 14 and the granular sludge supplied from the recycle hopper 15, that is, the dry sludge A and the sludge storage hopper 11 are stored. The dewatered sludge is kneaded and granulated by the biaxial mixer 12.
The sludge kneaded and granulated by the biaxial mixer 12 is dried by the drying drum 13 to become the dried sludge B, which is supplied to the classification bag filter 14 together with the drying gas.

In the classification bag filter 14, granular sludge having a particle size equal to or larger than the set particle diameter is separated from the dried sludge B by the classification unit 20 and conveyed by the dried sludge supply conveyor 17. Part of the granular sludge conveyed by the dry sludge supply conveyor 17 is charged into the product supply hopper 16, and the remainder is charged into the recycle hopper 15.
The granular sludge charged in the product supply hopper 16 is shipped as a product, and the granular sludge charged in the recycle hopper 15 is supplied again to the biaxial mixer 12 by the dry sludge recycle conveyor 18.

On the other hand, the dried sludge C (= dried sludge B-granular sludge having a particle size equal to or larger than the set particle size) that has passed through the classification unit 20 of the classification bag filter 14 is collected by the collection unit 21 of the classification bag filter 14 and then dried. It is supplied to the twin-screw mixer 12 by the sludge feeder 19 and the dried sludge recycling conveyor 18. That is, the dried sludge A obtained by removing the product from the dried sludge B is supplied to the biaxial mixer 12.
In addition, the dry sludge C discharged | emitted from the collection part 21 of the classification bag filter 14 is mainly powder sludge.

A classification bag filter 14 according to the present embodiment is shown in FIGS.
The classification bag filter 14 separates the granular sludge having a particle size equal to or larger than the set particle diameter from the dried sludge B discharged from the drying drum 13 together with the dry gas, and a plurality of the collected sludge C that has passed through the classified section 20. And a collection unit 21 provided with a filter 28.

The classification unit 20 includes an ascending chamber 20a in which the drying gas rises and a descending chamber 20b in which the rising drying gas descends.
Each filter 28 installed in the collection unit 21 includes a cylindrical retainer (not shown) formed of a wire rod and a filter cloth (not shown) covering the periphery of the retainer, and is arranged in the vertical direction. ing. The bottom surface side of the filter 28 is an inlet for the dry gas, and the upper surface side is an outlet for the dry gas, and the plurality of filters 28 are regularly arranged in a matrix so as to cover almost the entire surface of the collection unit 21 in plan view. Each filter 28 filters and collects powder on the cylindrical side surface and bottom surface excluding the top surface.

The classification bag filter 14 has a rectangular shape in plan view, and is arranged in the order of the ascending chamber 20a, the descending chamber 20b, and the collecting portion 21 from the short side of the drying drum 13 toward the other short side. (See FIG. 2A).
As shown in FIG. 2B, the cross-section in the short side direction of the classification bag filter 14 is a V-shaped cross section in which the lower cross section is reduced downward, and the first sludge that discharges granular sludge having a particle size equal to or larger than the set particle diameter A discharge port 25 is provided at the bottom of the ascending chamber 20 a, and a second discharge port 26 for discharging the dried sludge C is provided at the bottom of the collection unit 21 adjacent to the classification unit 20. Further, a screw conveyor 27 that penetrates the classification unit 20 and the collection unit 21 is installed at the bottom of the classification bag filter 14 along the long side direction of the classification bag filter 14.

  In the lower part of the ascending chamber 20a, an intake port 22 for sucking dry gas discharged from the drying drum 13 together with the dried sludge B is provided. The dried sludge B that has entered the ascending chamber 20a together with the drying gas from the intake port 22 rises in the ascending chamber 20a. At that time, the granular sludge having a terminal velocity larger than the air flow velocity of the dry gas in the ascending chamber 20a falls without being raised and is discharged from the first outlet 25 provided at the bottom of the ascending chamber 20a.

The dry gas and the dried sludge C that have passed through the ascending chamber 20a of the classifying unit 20 enter the lower part of the collecting unit 21 via the descending chamber 20b of the classifying unit 20, and pass through the filter 28 from below to above. To do. At that time, the dried sludge C is collected on the filter cloth of the filter 28. Top of the collecting unit 21 is a vent portion 21a serving as a passage of drying gas which has passed through the filter 28, the vent portion 21a of the termination to (classification bag filter other short side side 14) dry gas exhaust port 23 Is provided. The dry gas discharged from the exhaust port 23 is heated by a heat exchanger (not shown) and then supplied to the drying drum 13 again.

A blow tube 29 is disposed in the short side direction of the classification bag filter 14 immediately above each filter 28. The blow tube 29 is equipped with an air nozzle (not shown), and the dry sludge C adhering to the filter cloth is removed by blowing backwashing gas injected from the air nozzle into the filter 28.
The dried sludge C removed from the filter cloth is transported by the screw conveyor 27 installed at the lower part of the collecting unit 21 and discharged from the second outlet 26 provided at the bottom of the collecting unit 21. .

  In addition, when the ratio of the dry sludge C increases rapidly compared with the separated granular sludge, a part of the dried sludge C is mixed into the separated granular sludge via the screw conveyor 27. Therefore, it is possible to avoid the production line from being stopped.

The passage cross-sectional area A of the dry gas in the ascending chamber 20a is determined based on the terminal velocity of the granular sludge having a set particle size.
The dry gas rising in the ascending chamber 20a is divided into a laminar flow region, a transition region, and a turbulent flow region according to the flow velocity. For example, assuming that the dry gas is a laminar flow, the Reynolds number Re is less than 1. When Re <1, the terminal velocity v of the sphere is expressed by the following equation.
v = 2ρπr ² g / 9 / μ
Where ρ: sphere density, r: sphere radius, g: gravitational acceleration, μ: fluid viscosity coefficient

Since the gravitational acceleration g and the viscosity coefficient μ of dry gas or air are known, assuming that the granular sludge is a sphere, the terminal velocity of the granular sludge depends on the density and particle size of the granular sludge from the above equation. I understand that. Since the density of the granular sludge is known, if the set particle diameter is determined, the terminal velocity of the granular sludge can be calculated.
On the other hand, the air flow velocity of the drying gas is obtained by dividing the volume per unit time of the drying gas flowing into the ascending chamber 20a by the passage cross-sectional area A of the drying gas in the ascending chamber 20a. The cross-sectional area of A = the volume of the dry gas flowing into the ascending chamber 20a per unit time / the air velocity of the dry gas.

Therefore, the passage cross-sectional area A of the dry gas in the rising chamber 20a can be determined by the following procedure.
(1) The particle size (set particle size) of the granular sludge to be separated is determined.
(2) The terminal velocity of granular sludge having a set particle size is calculated.
(3) Based on the terminal velocity of the granular sludge having a set particle size, an air velocity smaller than the terminal velocity of the granular sludge is set as the air velocity of the dry air.
(4) The passage cross-sectional area A of the drying gas in the ascending chamber 20a is calculated from the volume per unit time of the drying gas flowing into the ascending chamber 20a and the air velocity of the drying air.

[Classifying bug filter according to the second embodiment]
The classification bag filter according to the second embodiment of the present invention is different from the classification bag filter according to the first embodiment in the structure of the classification unit. A classification bag filter 24 according to the second embodiment is shown in FIGS. In the following description, the same components are denoted by the same reference numerals and description thereof is omitted.

  The classifying unit 30 of the classifying bag filter 24 also has an ascending chamber 30a in which the drying gas rises and a descending chamber 30b in which the rising drying gas descends. The structure of the ascending chamber 30a is the same as that of the previous embodiment. Is different. In the present embodiment, the passage space for the dry gas in the ascending chamber 30a is constituted by a plurality of divided chambers 35 that are divided in directions perpendicular to the direction in which the dry gas passes (the short side direction and the long side direction of the classification bag filter 24). Has been. A damper 36 is installed at the lower end of the one or more divided chambers 35.

  Each damper 36 rotates in a vertical plane and adjusts the opening area of the lower end surface of the divided chamber 35 in which the damper 36 is installed. Thereby, the passage area of the dry gas in the ascending chamber 30a is adjusted to separate the granular sludge having a particle size larger than the set particle size.

[Classifying bug filter according to the third embodiment]
The classification bag filter according to the third embodiment of the present invention is different from the classification bag filter according to the first embodiment in the structure of the classification unit, similarly to the bug filter according to the second embodiment. FIGS. 4A and 4B show a classification bag filter 34 according to the third embodiment.

  The classification part 40 of the classification bag filter 34 also has a rising chamber 40a in which the drying gas rises and a lowering chamber 40b in which the rising drying gas descends. The structure of the rising chamber 40a is the same as that of the previous embodiment. Is different. In the present embodiment, a part 41 of the side wall forming the rising chamber 40a is movable toward the opposing side wall 42 (partition walls of the rising chamber 40a and the lowering chamber 40b).

The side wall part 41 includes an upper rotating wall 41a that rotates in the vertical plane with the upper edge serving as a support shaft, a lower rotating wall 41c that rotates in the vertical surface using the lower edge as a supporting shaft, The upper and lower ends are composed of an upper rotating wall 41a and a lower moving wall 41c, and a horizontal moving wall 41b that moves in the horizontal direction.
By moving part 41 of the side wall toward the opposing side wall 42, the passage area of the dry gas in the ascending chamber 40a is adjusted to separate the granular sludge having a particle size equal to or larger than the set particle size.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the above-described embodiments, and is considered within the scope of the matters described in the claims. Other embodiments and modifications are also included.

10: granulation drying system, 11: sludge storage hopper, 12: twin screw mixer (mixer), 13: drying drum, 14, 24, 34: classification bag filter, 15: recycling hopper, 16: product supply hopper, 17: Dry sludge supply conveyor, 18: Dried sludge recycling conveyor, 19: Dried sludge feeder, 20, 30, 40: Classification section, 20a, 30a, 40a: Ascending chamber, 20b, 30b, 40b: Descent chamber, 21: Collection section 21a: Ventilation part, 22: Intake port, 23: Exhaust port, 25: First exhaust port, 26: Second exhaust port, 27: Screw conveyor, 28: Filter, 29: Blow tube, 31: Bag filter 32: Vibrating sieve, 35: Division chamber, 36: Damper, 41: Part of the side wall, 41a: Upper rotating wall, 41b: Horizontal moving wall, 41c: Lower rotating wall, 42: Side wall toward

Claims (4)

After dewatered sludge and dried sludge A are kneaded and granulated with a mixer, they are dried with a drying drum to form dried sludge B, and a part of the granular sludge contained in dried sludge B is used as a product. A classification bag filter installed in a granulation drying system for supplying sludge A to the mixer,
The classification bag filter includes a classification unit for separating granular sludge having a particle size equal to or larger than a set particle size from the dried sludge B discharged from the drying drum together with a dry gas, and a plurality of the collected sludge C that has passed through the classification unit. A collection part provided with a filter,
The classifying unit includes an ascending chamber in which the drying gas rises and a descending chamber in which the rising drying gas descends, and the granular sludge having a terminal velocity larger than the air velocity of the drying gas in the ascending chamber is in the ascending chamber. Discharged from the outlet provided at the bottom,
The classification bag filter according to claim 1, wherein a passage cross-sectional area of the dry gas in the ascending chamber is determined based on a terminal velocity of granular sludge having the set particle diameter. After dewatered sludge and dried sludge A are kneaded and granulated with a mixer, they are dried with a drying drum to form dried sludge B, and a part of the granular sludge contained in dried sludge B is used as a product. A classification bag filter installed in a granulation drying system for supplying sludge A to the mixer,
The classification bag filter includes a classification unit for separating granular sludge having a particle size equal to or larger than a set particle size from the dried sludge B discharged from the drying drum together with a dry gas, and a plurality of the collected sludge C that has passed through the classification unit. A collection part provided with a filter,
The classifying unit includes an ascending chamber in which the drying gas rises and a descending chamber in which the rising drying gas descends, and the granular sludge having a terminal velocity larger than the air velocity of the drying gas in the ascending chamber is in the ascending chamber. Discharged from the outlet provided at the bottom,
The drying gas passage space in the ascending chamber is composed of a plurality of division chambers divided in a direction orthogonal to the passage direction of the drying gas, and a damper is installed at the lower end of one or more of the division chambers. Classification bug filter to do. After dewatered sludge and dried sludge A are kneaded and granulated with a mixer, they are dried with a drying drum to form dried sludge B, and a part of the granular sludge contained in dried sludge B is used as a product. A classification bag filter installed in a granulation drying system for supplying sludge A to the mixer,
The classification bag filter includes a classification unit for separating granular sludge having a particle size equal to or larger than a set particle size from the dried sludge B discharged from the drying drum together with a dry gas, and a plurality of the collected sludge C that has passed through the classification unit. A collection part provided with a filter,
The classifying unit includes an ascending chamber in which the drying gas rises and a descending chamber in which the rising drying gas descends, and the granular sludge having a terminal velocity larger than the air velocity of the drying gas in the ascending chamber is in the ascending chamber. Discharged from the outlet provided at the bottom,
A classification bag filter, wherein a part of the side wall forming the rising chamber is movable toward the opposite side wall. The classification bag filter of any one of Claims 1-3 WHEREIN: The screw conveyor installed in the lower part of the said collection part is extended to the said classification part, The classification bag filter characterized by the above-mentioned.

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