JP7503235B2 - Screw press discharge section dewatered cake removal device - Google Patents

Description

The present invention relates to a dehydrated cake removal device for the discharge section of a screw press that forcibly drops dehydrated cake that is discharged to the outside from the screen end of the screw press.

Screw presses are commonly known for concentrating and dewatering organic sludge such as sewage, human waste, or wastewater from food production and processing. A screw press has a screw blade inserted into a cylindrical screen, and the screw blade rotates to transport the sludge while separating the solid and liquid on the screen. The dewatered cake continuously discharged from the screw press is mainly disposed of as a landfill, incinerated, composted, etc.

The properties of the sludge fed to the screw press vary depending on the season and time, and the moisture content of the dehydrated cake discharged from the screw press varies accordingly. Fluctuations in the moisture content of the dehydrated cake not only affect the amount and transportation costs from the treatment plant, but also affect the landfill capacity, fuel costs for incineration, and composting time and quality.

The moisture content of the dehydrated cake can be calculated from the weight and volume of the dehydrated cake and the true specific gravity of the solids, but it is difficult to determine the volume in a screw press that operates continuously. In order to control the screw press based on the moisture content of the dehydrated cake, a means of accurately calculating the volume of the dehydrated cake in real time was desired.

As in the screw press described in Patent Document 1, dehydrated cake is generally discharged along a cone-shaped resistor provided at the discharge section at the end of the screen. As shown in Figure 3, the dehydrated cake discharged in a circular shape falls successively under its own weight and is transported by a conveyor or the like.

Patent document 2 discloses a technology in which the tapered cone of the resistor that forms the discharge port of the screw press is moved backward, and then air is sprayed from an air nozzle to blow away the dehydrated cake that has become clogged near the discharge port.

JP 2018-192513 A JP 2015-199044 A

Conventionally, the volume of dehydrated cake in a screw press can be easily calculated from the volume of the filtration chamber. However, as disclosed in FIG. 3 of Cited Document 1, the dehydrated cake discharged from the screw press adheres to the discharge section in an irregular ring shape. It falls one by one under its own weight, but it is particularly difficult for the dehydrated cake discharged from above to fall downward, and it is difficult to predict when it will fall.

As a result, it was difficult to calculate the volume of the dehydrated cake adhering to the discharge section at the start and end of the discharge, which corresponds to the weight of the dehydrated cake discharged per unit time, and it was not possible to calculate the moisture content of the dehydrated cake from the accurate volume in real time.

Patent Document 2 automatically squeezes out dehydrated cake stuck in the dehydrated cake discharge port. After moving the tapered cone of the resistor backward, air is sprayed from an air nozzle to blow away the dehydrated cake stuck near the discharge port, but as shown in Figure 6, even the dehydrated cake inside the filtration chamber near the discharge end is blown away. As with Patent Document 1, it is difficult to calculate the volume of the dehydrated cake blown away at the start and end of the volume corresponding to the weight of the dehydrated cake discharged per unit time, and it is not possible to calculate the moisture content of the dehydrated cake from the accurate volume in real time.

The present invention provides a device for removing dehydrated cake from the discharge section of a screw press, which closes the discharge section to determine the volume of the filtration chamber, and forcibly removes dehydrated cake adhering to the outside of the discharge section, making it easy to determine the weight and volume of the dehydrated cake to be measured.

The present invention relates to a screw press in which a filtration chamber is formed by rotatably installing a screw shaft around which a screw blade is wound inside a screen, raw liquid supplied from one end of the filtration chamber is transported to the other end while being dehydrated, and dehydrated cake is discharged from a discharge section formed by an end of the screen and a pressure plate. The screw press is equipped with a dehydrated cake removal device comprising: an annular separation plate divided into multiple parts; and a drive source which swings the separation plate so as to be freely separable and detachable to open and close the discharge section, and which expands the inner diameter of the separation plate outward from the outer diameter of the discharge section when opening and adjusts the inner diameter of each separation plate to a position where it comes into contact with the pressure plate when closing, and which makes it possible to easily identify the weight and volume of the dehydrated cake when measuring.

By using a link mechanism to simultaneously swing the multiple separation plates, power can be reduced and multiple separation plates can be easily synchronized.

When the discharge section is blocked by the separation plate, a peeling member is provided to remove the dehydrated cake adhering to the pressure plate, so that the dehydrated cake adhering to the pressure plate can be dropped reliably.

The discharge section dehydrated cake removal device in the screw press of the present invention, when measuring the volume of dehydrated cake in the filtration chamber being transported by the screw blades, forcibly drops the adhering part of the dehydrated cake that is discharged to the outside from the end of the screen at the start and end of the measurement. Since the weight during the measurement period corresponds only to the volume of the filtration chamber, it is possible to accurately calculate the moisture content of the dehydrated cake in real time.

1 is a schematic cross-sectional side view of a screw press according to the present invention. FIG. 2 is a front view of the dewatered cake removal device according to the present invention. FIG. 4 is a front view of a dewatered cake removal device according to another embodiment of the present invention. FIG. 11 is a front view of a dewatered cake removal device according to another embodiment of the present invention when it is closed. FIG. 11 is a front view of a dewatered cake removal device according to another embodiment of the present invention when it is open. FIG. 4 is a front view of a separation plate to which a peeling member according to the present invention is attached. FIG. 4 is a plan view of a separation plate to which a peeling member according to the present invention is attached. FIG. 11 is a partial cross-sectional side view of a peeling member according to another embodiment of the present invention.

Figure 1 is a schematic side cross-sectional view of a screw press according to the present invention. Reference numeral 1 denotes a screw press, which has a screen 2 having a filtering surface on its periphery and a screw shaft 4 with screw blades 3 wound around it, forming a filtering chamber 5 between them. The diameter of the screw shaft 4 disposed inside the screen 2 increases in a tapered manner from the starting end to the terminal end, and the relative distance between the screen 2 and the screw shaft 4 decreases in the extension direction. The screw shaft 4 extended to the discharge side is rotated by a screw driver (not shown).

A supply pipe 6 is connected to the starting end of the screw shaft 4, and the supply pipe 6 is connected to a supply hole 7 of the screw shaft 4 that opens on the starting end side of the screen 2. The raw liquid is supplied from the supply pipe 6 through the supply hole 7 to the starting end of the filtration chamber 5. The supply pipe 6 may be connected to the cylindrical screen 2 or the starting end wall of the filtration chamber 5 to supply the raw liquid to the filtration chamber 5.

The raw liquid supplied to the filtration chamber 5 is transported from the start to the end by the screw blades 3, and is concentrated and dehydrated while separating the filtrate from the screen 2. The dehydrated cake dehydrated in the filtration chamber 5 is discharged from the discharge section 9 formed between the end of the screen 2 and the pressure plate 8.

The discharge section 9 is equipped with a dehydrated cake removal device 10 that can swing freely. The dehydrated cake removal device 10 is provided close to the end of the screen 2, and is positioned outside so as not to obstruct the dehydrated cake discharged from the discharge section 9 during normal operation of the screw press 1. When forcibly removing the dehydrated cake in the discharge section 9 that is being discharged to the outside from the end of the screen 2, the discharge section 9, which is composed of the opening between the pressure plate 8 and the end of the screen 2, is closed, and the edge between the dehydrated cake adhering to the outside of the discharge section 9 and the dehydrated cake in the filtration chamber 5 is cut off, causing the dehydrated cake adhering to the outside of the discharge section 9 to fall downward.

Figure 2 is a front view of the dehydrated cake removal device according to the present invention. The dehydrated cake removal device 10 is composed of a number of annular separation plates 11... and a drive source 13 (not shown) that swings the separation plates 11.

In this embodiment, annular separation plates 11, 11 divided into two parts, left and right, are used, and when each separation plate 11, 11 is expanded, the inner diameter of the separation plate 11 is positioned outside the outer diameter of the discharge portion 9. In addition, when each separation plate 11, 11 is mated, the inner diameter of the annular shape is adapted to the outer diameter at the position where it contacts the pressing plate 8, and the mating surfaces of the separation plates 11, 11 are adapted so that no gap is generated. The inner surface and mating surfaces of the separation plate 11 may be provided with a cushioning material such as rubber or resin. The outer diameter of the separation plate 11 is appropriately determined according to the opening (screen inner diameter) of the discharge portion 9.

In this embodiment, the separation plate 11 is configured to be freely detachable by swinging horizontally. Each separation plate 11, 11 may be connected to a drive source 13, 13 to move them directly, or a single drive source 13 may be used to move them simultaneously using a link mechanism (not shown).

In this embodiment, the separation plate 11 is swung horizontally, but there is no problem if it is moved vertically or diagonally.

3 is a front view of the dewatered cake removal device according to another embodiment 1. The three-part annular separation plate 11 is configured to be movable horizontally so as to be freely joined and separated. In this way, the separation plate 11 may be divided into three or more parts depending on the installation position, etc., so as to be freely joined and separated.

4 and 5 are front views of a dewatered cake remover according to another embodiment 2 when it is closed and when it is open . The dewatered cake remover 10 is composed of two divided annular separation plates 11, 11, a link mechanism 12 that swings the multiple separation plates 11 so that they can be freely connected and disconnected, and a cylinder 13 connected to the link mechanism 12.

The link mechanism 12 in the second embodiment is configured in a pantograph shape, with the ends of the arms 14, 14 connected to the separation plates 11, 11, the middle parts of the arms 14, 14 rotatably connected by fixed pins 15, the other ends of the arms 14 connected to the arms 17, 17 by swing pins 16, and the other ends of the arms 17, 17 connected to the rods of the cylinders 13 used as drive sources.

When the rod of the cylinder 13 is shortened, the fixed pin 15 acts as a fulcrum, narrowing the distance between the arms 14, 14 as shown in Figure 4, and bringing the two separation plates 11, 11 into alignment. The aligned separation plates 11 close the discharge section 9 of the screw press 1.

When the rod of the cylinder 13 is extended, the fixed pin 15 serves as a fulcrum, and the distance between the arms 14, 14 increases, causing the two separation plates 11, 11 to open to the left and right, as shown in FIG.
The fixing pin 15 and the cylinder 13 are appropriately fixed to the members constituting the screw press 1 or to auxiliary materials.

In this embodiment, a pantograph-shaped link mechanism 12 is used, but any mechanism that can swing the separation plate 11 so that it can be separated can be selected as appropriate. In addition, there is no limitation as long as it can be used as a drive source other than the cylinder 13.

6 and 7 are respectively a front view and a plan view of a separation plate equipped with a peeling member according to the present invention. A peeling member 18 is attached to the discharge side of the separation plate 11, and when the separation plate 11 is brought together to close the filtration chamber 5, the dehydrated cake adhering to the pressure plate 8 is pushed out by the peeling member 18. The dehydrated cake adheres to the pressure plate 8 while being discharged in a ring shape, and the peeling member 18 cuts the ring from the tangential direction and promotes the falling of the cake by its own weight.

The peeling member 18 is attached along the joining plate 11, with the end of the peeling member 18 protruding from the mating surface of the joining plate 11. The peeling member 18 may be attached to each mating surface, but it is preferable to attach it to the upper mating surface, especially since the dehydrated cake is less likely to fall due to its own weight at the upper part. The size and protruding length of the peeling member 18 can be selected appropriately depending on the specifications of the screw press 1.

Figure 8 is a partial cross-sectional side view of a peeling member according to another embodiment. It is characterized by spraying high-pressure air onto the dehydrated cake adhering to the pressure plate 8 to forcibly peel it off. The peeling member 18 is composed of a nozzle 19 attached to the discharge side of the separation plate 11, an air pipe 20 that supplies high-pressure air to the nozzle 19, and a high-pressure air source 21. After the separation plate 11 is brought together to close the filtration chamber 5, high-pressure air is sprayed from the nozzle 19 to remove the dehydrated cake adhering to the pressure plate 8.

If it is possible to remove the dehydrated cake adhering to the pressure plate 8, the nozzles 19 may be installed inside the pressure plate 8 or in a position opposite the pressure plate 8. The number of nozzles 19 to be installed is determined appropriately according to the specifications of the screw press 1. The direction of the nozzles 19 may be oriented in the tangential or radial direction of the annular pressure plate 8, and it is desirable to install a member to receive the scattered dehydrated cake.

The discharge section dehydrated cake removal device in the screw press of the present invention temporarily blocks the discharge section in the filtration chamber of a continuously operating screw press to forcibly remove dehydrated cake adhering to the pressure plate, making it easy to determine the sludge volume at the start and end of measurement. This makes it possible to calculate an accurate moisture content of the dehydrated cake, and stably control the screw press according to the real-time moisture content of the dehydrated cake. The properties of the raw liquid to be treated change from moment to moment depending on the season, weather, etc., and this is particularly effective for continuous screw presses that separate sewage sludge, which is made up of a variety of solids, into solid-liquid separation.

Reference Signs List 1 Screw press 2 Screen 3 Screw blade 4 Screw shaft 5 Filtration chamber 8 Pressing plate 9 Discharge section 10 Dewatered cake removal device 11 Separation plate 12 Link mechanism 13 Driving source 18 Peeling member

Claims (3)

In a screw press (1), a filtration chamber (5) is formed by rotatably installing a screw shaft (4) around which a screw blade (3) is wound inside a screen (2), a raw liquid supplied from one end of the filtration chamber (5) is conveyed to the other end while being dehydrated, and a dehydrated cake is discharged from a discharge section (9) formed by an end of the screen (2) and a pressure plate (8),
A circular separation plate (11) divided into multiple parts;
a drive source (13) that swings the separation plates (11) so as to be freely separable from each other to open and close the discharge section (9), and that expands the inner diameter of the separation plates (11) outward from the outer diameter of the discharge section (9) when opening, and adjusts the inner diameter of each separation plate (11) to a position where it comes into contact with the pressure plate (8) when closing ;
A dewatered cake removal device for a discharge section of a screw press, comprising: a dewatered cake removal device (10) comprising: 2. The device for removing dewatered cake from a discharge section in a screw press according to claim 1, wherein the plurality of separation plates (11) are swung simultaneously by a link mechanism (12). When the discharge portion (9) is closed by the separation plate (11),
2. The device for removing dehydrated cake from a discharge section of a screw press according to claim 1, further comprising a peeling member (18) for removing the dehydrated cake adhering to the pressing plate (8).

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