JP2015208707A - Apparatus and method for reducing water content of dehydrated cake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for reducing the water content of dehydrated cake, in each of which the water content of the dehydrated cake, that is obtained by dehydrating the excess sludge generated in flocculation precipitation treatment by a dehydrator and discharged from the dehydrator, can be reduced easily and at a low cost.SOLUTION: An apparatus for reducing water content of dehydrated cake includes: a conveyor for conveying the dehydrated cake; a cylindrical windshield cover for covering the conveyor; and a fan which is arranged in the vicinity of the inlet end of the cylindrical windshield cover and used for sending air to the dehydrated cake. The conveyor is constituted so that the residence time of the dehydrated cake to be conveyed becomes 45-90 minutes. The fan is constituted so that the air to be sent to the dehydrated cake flows in the windshield cover from the inlet end thereof to the outlet end at 2 m/sec or higher wind speed at room temperature and a reduced ratio of the water content of the dehydrated cake becomes 15% or higher before and after air is sent to the dehydrated cake.

Description

  The present invention relates to a dehydrating cake moisture content reducing device and a dewatering cake moisture content reducing method. More specifically, the present invention relates to a dehydration cake moisture content reduction device and a dehydration cake moisture content reduction method that can easily and inexpensively reduce the moisture content of a dehydrated cake discharged from a dehydrator.

  In the coagulation sedimentation process, sludge containing an inorganic coagulant is generated. In order to reduce the cost and capacity of industrial waste, solid-liquid separation is performed by a dehydrator to reduce the water content. As a method of reducing the moisture content of such a dehydrated cake, for example, a corrugated conveyor device, a drying box that covers the corrugated conveyor, and a blower fan for generating an air flow in the drying box are provided, and are to be dried. There has been proposed a drying apparatus for drying an object by sunlight and ventilation (for example, see Patent Document 1).

  In addition, when solid-liquid separation is performed by a dehydrator, the amount of chemicals such as an inorganic flocculant and a polymer flocculant is increased, thereby improving water drainage in the dehydrator and increasing the moisture content of the dehydrated cake. A method for reducing the temperature and a method using a dryer using heating by steam or the like have been proposed.

Japanese Patent No. 3348068

  However, since the drying apparatus described in Patent Document 1 is affected by the weather in the sun-dried portion, it is difficult to stably reduce the moisture content, and drying by ventilation is also performed. In the part, in order to cover a large-scale corrugated conveyor and a plurality of blower fans for applying air to the entire surface of the object to be dried conveyed by the corrugated conveyor, a large-scale drying box is required, Depending on the weather, it was necessary to open and close the ceiling of the drying device in order to prevent the inflow of rainwater, which had to be a large and complicated device.

  In addition, there is a problem that the method of increasing the injection amount of chemicals is accompanied by an increase in the cost of chemicals. The method using a dryer using heating by steam or the like greatly increases the generation of steam when there is no surplus steam. There is a problem that the cost increases.

  The present invention has been made in view of the above-mentioned problems, and a dehydration cake moisture content reduction device and a dehydration cake that can easily and inexpensively reduce the moisture content of a dewatered cake discharged from a dehydrator. An object of the present invention is to provide a method for lowering the moisture content of

  As a result of earnest research conducted by the inventors to achieve the above object, the dewatered cake discharged from the dehydrator is transported by a conveyor or the like for transportation or movement to a deposition site. By blowing air on the dehydrated cake under specified conditions (by applying air), the moisture content is further reduced, reducing the cost and capacity of industrial waste (ie, operating expenses such as electricity costs, transportation costs, etc.) The cost can be reduced), and the effect can be increased by operating the conveyor under specified conditions and increasing the residence time on the conveyor, The present invention has been completed. That is, according to the present invention, the following dehydrating cake moisture content reducing device and dehydrating cake moisture content reducing method are provided.

[1] A conveyor for transporting the dewatered cake formed after the excess sludge from the coagulation sedimentation process is dehydrated by the dehydrator, and a cylindrical windshield cover for covering at least the upper part of the conveyor; A fan that is provided in the vicinity of the inlet end of the windshield cover and blows air to the dewatered cake to be conveyed, and the conveyor has a residence time of the dewatered cake to be conveyed of 45 to 90 minutes. The fan is configured such that air blown to the dewatered cake is performed at room temperature at a wind speed of 2 m / sec or more and in the windshield cover in a direction from the inlet end toward the outlet end. In addition, the reduction rate of the moisture content of the dehydrated cake before and after the blowing treatment [{(water content at the inlet end−water content at the outlet end) / (water content at the inlet end)} × 100] , Water content reduction device dehydrated cake which is characterized by comprising is configured to be 15% or more.

[2] The dehydrating cake moisture content reducing device according to [1], wherein the dehydrated cake has a pellet shape or a lump shape with a thickness of 10 to 50 mm.

[3] The windshield cover has a windshield curtain at the entrance end, and the windshield curtain can introduce a dewatered cake at a position in contact with the conveyor, and is accumulated on the conveyor and piled up. The dehydrating cake moisture content reducing device according to the above [1] or [2], which has an opening notch for uniformly spreading the cake.

[4] The dewatered cake formed by discharging the excess sludge from the coagulation sedimentation process after being dehydrated by the dehydrator is loaded on a conveyor whose upper part is covered with a cylindrical windshield cover. Then, using a fan provided in the vicinity of the inlet end of the windshield cover, with respect to the step of transporting with a residence time of 45 to 90 minutes, and the dewatered cake loaded and transported on the conveyor, At room temperature, with a wind speed of 2 m / sec or more and in the windshield cover in a direction from the inlet end toward the outlet end, the rate of decrease in the moisture content of the dehydrated cake before and after the blowing treatment [{( The moisture content at the inlet end—the moisture content at the outlet end) / (the moisture content at the inlet end)} × 100] is blown so as to be 15% or more. Rate decrease method.

[5] The method for reducing the water content of the dehydrated cake according to [4], wherein the dehydrated cake is in the form of a pellet or a lump having a thickness of 10 to 50 mm.

[6] The windshield cover has a windshield curtain at the entrance end, and the windshield curtain is capable of introducing a dewatered cake at a position in contact with the conveyor, and is accumulated on the conveyor and piled up. The method for lowering the moisture content of a dehydrated cake according to the above [4] or [5], wherein the cake has an opening notch for uniformly spreading the cake.

  ADVANTAGE OF THE INVENTION According to this invention, the moisture content fall apparatus and the moisture content fall method of a dewatered cake which can reduce the moisture content of the dehydrated cake discharged | emitted from the dehydrator simply and at low cost are provided.

It is explanatory drawing which shows typically the moisture content decreasing apparatus of the spin-drying | dehydration cake which concerns on embodiment of this invention. It is a perspective view which shows typically the moisture content decreasing apparatus of the dewatering cake which concerns on embodiment of this invention. It is explanatory drawing at the time of seeing the windshield cover and windshield curtain which are used for the moisture content decreasing device of the dehydrated cake according to the embodiment of the present invention from the entrance end side of the windshield cover.

1. As shown in FIG. 1, the dehydrating cake moisture content reducing device 10 according to the embodiment of the present invention is configured such that the excess sludge from the coagulation sedimentation process is dehydrated by the dehydrator 20. A conveyor 2 that transports the dehydrated cake 1 formed by being discharged from the pipe, a cylindrical windshield cover 3 that covers at least the upper part of the conveyor 2, and a conveyor provided in the vicinity of the inlet end 31 of the windshield cover 3. A fan 4 that blows air to the dewatered cake 1, and the conveyor 2 is configured so that the residence time of the dewatered cake 1 being conveyed is 45 to 90 minutes. At room temperature, the windshield cover 3 is constructed so that the wind speed is 2 m / second or more and in the direction from the inlet end 31 toward the outlet end 32, and the moisture content of the dewatered cake 1 is before the blowing process. On the other hand, it is configured to decrease at a rate of 15% or more. Hereinafter, each component will be described.

1-1. Dehydrated cake The dehydrated cake 1 used in the present embodiment has a water content of preferably 20 to 40% by mass, for example, by the dehydrator 20 shown in FIG. So dehydrated. Usually, the thickness is 10 to 50 mm in the form of pellets or lumps, but is not limited thereto. If it is less than 10 mm, it may soar in the air due to the high wind speed, which is not preferable for work, and if it exceeds 50 mm, the water content may be insufficiently reduced. As shown in FIG. 1, the dewatered cake 1 is placed on a conveyor 2, which will be described later, via a chute 21 configured to discharge the dehydrated cake 1 in a predetermined shape from the dehydrator 20. Placed.

1-2. Conveyor The conveyor 2 used for this Embodiment is normally comprised so that the residence time of the dewatering cake 1 conveyed may be 45 to 90 minutes. For example, in the relationship between the length of the conveyor 2 and the conveyance speed, it can be mentioned that the length of the conveyor 2 is relatively long or the conveyance speed is relatively small, and the conveyor 2 is operated for a predetermined time. And so-called intermittent operation of stopping for a predetermined time can be mentioned. For example, setting the conveyor 2 to have a length of 10 m and a conveyance speed of 2.5 m / min, and performing an intermittent operation in which the conveyor 2 is operated for 1 minute and stopped for 14 minutes. Can do. In this case, the operation time of the conveyor 2 is 10 m ÷ 2.5 m / min = 4 minutes, and the stop time of the conveyor 2 is 14 minutes × 4 = 56 minutes. As a result, the residence time of the dewatered cake 1 is the operation time of the conveyor 2 + stop time = 4 minutes + 56 minutes = 60 minutes. By comprising in this way, the residence time on a conveyor can be lengthened and the moisture content of a dewatering cake can be reduced effectively. The conveyor 2 is configured to rise from an inlet end 31 side to an outlet end 32 side of the windshield cover 3 to be described later, for example, at an inclination angle of 0 to 20 degrees, preferably 5 to 15 degrees. From the aspect, it is preferable. There is no restriction | limiting in particular about the form of a conveyor 2, a drive capability, etc.

1-3. Windshield cover In the present embodiment, for example, a windshield cover 3 is provided so as to cover at least the upper part of the conveyor 2. The shape of the air can be efficiently blown in one direction from the inlet end 31 side to the outlet end 32 side by the fan 4, which will be described later. For example, the cylindrical shape is not particularly limited, but is cylindrical. Or it is preferable that it is a rectangular tube shape. The cross section may be a cylindrical shape such as a substantially semicircle, a semi-ellipse, a semi-ellipse, or a semi-track shape, or the cross section may be a rectangular tube such as a substantially triangle, rectangle, square, or polygon. FIG. 3 shows a case of a cylindrical shape having a substantially semicircular cross section. Further, the material is preferably made of a transparent or translucent plastic capable of observing the state of the dehydrated cake 1, but is not particularly limited.

1-4. Fan The fan 4 used for this Embodiment is used in order to implement | achieve the reduction | decrease in the moisture content of the dewatering cake 1 by the ventilation to the dewatering cake 1 efficiently. The dewatering cake 1 is blown at room temperature at a wind speed of 2 m / sec or more, preferably 4 m / sec or more, and in the windshield cover 3 in a direction from the inlet end 31 toward the outlet end 32. Configured as follows. In addition, it was confirmed by the evaluation test mentioned later that a wind speed does not lead to the remarkable reduction | decrease in a moisture content, for example, even if it exceeds 6 m / sec. In addition, the fan 4 used in the present embodiment has a reduced rate of moisture content of the dewatered cake 1 before and after the blowing process [{(water content at the inlet end−water content at the outlet end) / (water content at the inlet end)]. } × 100] is configured to be 15% or more. If it is less than 15%, it becomes difficult to reduce the cost and capacity of industrial waste (that is, reduction of operating costs such as electricity bills and transportation costs). There is no restriction | limiting in particular about the form of a fan 4, a drive capability, etc.

1-5. Other Components As shown in FIG. 3, in the present embodiment, it is possible to have the windshield curtain 5 at the entrance end 31 of the windshield cover 3 so that the wind speed is stable from the entrance end 31 to the exit end 32 of the windshield cover 3. It is preferable that the dehydrated cake 1 piled on the conveyor 2 can be uniformly spread and spread. The windshield curtain 5 can introduce the dewatered cake 1 at a position in contact with the conveyor 2, and has an opening notch 51 for uniformly spreading the dewatered cake 1 piled on the conveyor 2. It is preferable. Thus, the windshield curtain 5 is preferably made of a material having predetermined flexibility and rigidity. For example, a polyimide resin such as “Nylon” (registered trademark), a polyolefin resin such as polypropylene, polyethylene, and vinyl chloride. And the like. Although there is no restriction | limiting in particular as thickness, For example, it is preferable to set it as 1-5 mm, and it is more preferable to set it as 1.5-3 mm. The shape of the opening cutout 51 is not particularly limited, but is preferably a rectangle having a long side corresponding to the width of the conveyor 2, for example. As described above, the long side is preferably the same length as the width of the conveyor, and the short side is preferably about 50 mm so that the dehydrated cake becomes a pellet or lump with a thickness of 10 to 50 mm. . Specifically, long side (conveyor width) × short side (40 to 60 mm) can be mentioned. In addition, in FIG. 1, it is shown that it is preferable that the ventilation to the dewatering cake 1 of the fan 4 is performed based on the external air 6 from the economical aspect, and the outlet end 32 side of the windshield cover 3 of the conveyor. Shows that the dewatered cake 1 discharged from is stored in, for example, the dewatered cake accumulation place 7, and further, the air blown by the fan 4 is directed from the inlet end 31 to the outlet end 32 of the windshield cover 3, that is, the air blown This shows that the operation is performed in the direction of direction 8.

2. Dehydration cake moisture content reduction method The dehydration cake moisture content reduction method of the present embodiment is a method of removing the dewatered cake 1 formed by discharging the excess sludge from the coagulation sedimentation treatment from the dehydrator 20 after being dehydrated by the dehydrator 20. , At least the upper part thereof is covered with a cylindrical windshield cover 3 and loaded on a conveyor and transported in a residence time of 45 to 90 minutes; and the dewatered loaded and transported on the conveyor 2 Using the fan 4 provided in the vicinity of the inlet end 31 of the windshield cover 3 with respect to the cake 1, the windshield cover 3 has a wind speed of 2 m / second or more at room temperature, and from the inlet end 31 to the outlet end 32. The moisture content of the dehydrated cake 1 before and after the blowing treatment is decreased [{(water content at the inlet end−water content at the outlet end) / (water content at the inlet end)} × 100]. , Is intended to include a step of blowing so that 15% or more, the.

  Here, the configuration, function, and the like of each component in each step are the same as those in the above-described dehydrating cake moisture content reduction device. Moreover, it is preferable that the dewatering cake 1 is in the form of a pellet or lump having a thickness of 10 to 50 mm. The windshield cover 3 preferably has a windshield curtain 5 at the inlet end 31 thereof. It is preferable that the water content reduction rate of 1 [{(water content at the inlet end−water content at the outlet end) / (water content at the inlet end)} × 100] is 15% or more. (If it is less than 15%, it is difficult to realize the reduction of the cost and capacity of industrial waste (that is, it is difficult to realize the operation cost such as electricity bill, the cost such as transportation cost)). .

  Hereinafter, the dehydrating cake moisture content reducing device and the dehydrating cake moisture content reducing method of the present invention will be described in more detail with reference to examples. Note that the present invention is not limited in any way by the following examples.

Example 1
A dehydrated cake, which is dehydrated by a dehydrator and discharged from the pellet, is 30 mm thick, 50 mm × 50 mm in size, and has a moisture content of 28.3 mass%. As shown, the conveyor (length is 10 m, width is 600 mm, inclination angle is 10.7 degrees, conveyance speed is set to 2.5 m / min, and the upper part is a cylindrical shape with a substantially semicircular cross section. A windshield curtain made of “Nylon” (registered trademark) with a thickness of 1.5 mm is installed at the entrance end of the windshield cover. It is configured to have a rectangular opening notch with a length equal to the width) × short side 50 mm), and the conveyor loaded with dewatered cake is intermittently operated (operated for 1 minute, stopped for 14 minutes). By The water cake was conveyed with a residence time of 60 minutes. For the dehydrated cake loaded and transported on this conveyor, a fan provided in the vicinity of the entrance end of the windshield cover is used, at room temperature, at a wind speed of 4 m / second, and inside the windshield cover at the entrance end. The air was blown in the direction toward the exit end. The moisture content after the blowing process was 19.2% by mass, and the reduction rate of the moisture content of the dewatered cake before and after the blowing process [{(moisture content at the inlet end−moisture content at the outlet end) / (moisture content at the inlet end] )} × 100] was [(28.3-19.2) /28.3] × 100 = 32 (%). Table 1 summarizes the fan wind speed, the residence time of the dehydrated cake, the moisture content, and the rate of decrease in moisture content.

(Examples 2-3)
In Example 1, as shown in Table 1, the procedure was the same as Example 1 except that the fan wind speed was changed to 2 and 6 m / sec. Table 1 shows the moisture content of the dehydrated cake and the decreasing rate of the moisture content.

Example 4
In Example 1, as shown in Table 1, the procedure was the same as Example 1 except that the intermittent operation of the conveyor (running for 1 minute, stopping for 11 minutes) and the residence time of the dehydrated cake was changed to 48 minutes. Table 1 shows the reduction ratio of the moisture content of the dehydrated cake.

(Example 5)
In Example 1, as shown in Table 1, the procedure was the same as Example 1 except that the intermittent operation of the conveyor (running for 1 minute, stopping for 21 minutes) and the residence time of the dehydrated cake was changed to 88 minutes. Table 1 shows the moisture content of the dehydrated cake and the decreasing rate of the moisture content.

(Example 6)
In Example 1, as shown in Table 1, it was the same as Example 1 except that the wind speed of the fan was changed to 8 m / sec. Table 1 shows the moisture content of the dehydrated cake and the decreasing rate of the moisture content.

(Comparative Example 1)
In Example 1, as shown in Table 1, the procedure was the same as Example 1 except that the fan wind speed was changed to 0.5 m / sec. Table 1 shows the moisture content of the dehydrated cake and the decreasing rate of the moisture content.

(Comparative Example 2)
In Example 1, as shown in Table 1, the procedure was the same as Example 1 except that the intermittent operation of the conveyor (1 minute operation, 3 minute stop) and the residence time of the dehydrated cake was changed to 16 minutes. Table 1 shows the moisture content of the dehydrated cake and the decreasing rate of the moisture content.

(Comparative Example 3)
In Example 1, as shown in Table 1, the size of the conveyor is increased about twice as much as in Example 1, and the intermittent operation of the conveyor (running for 1 minute, stopping for 29 minutes) causes the dewatered cake to stay. Example 1 was repeated except that the time was changed to 120 minutes. Table 1 shows the moisture content of the dehydrated cake and the decreasing rate of the moisture content.

  Table 1 shows the following. That is, in the case of Examples 1 to 5, while setting the fan wind speed to 2, 4, 6 or 8 m / sec and setting the residence time of the dewatered cake on the conveyor to 48, 60 or 88 minutes within the specified range, It turns out that the moisture content entered the range of 16.7-21.5 mass%, respectively (a reduction rate of 24-41%), and the moisture content was effectively reduced. In the case of Example 6 (fan wind speed set to 8 m / sec), a slightly better result was obtained than in the case of Example 1, but since the wind speed was doubled, the running cost was Compared with the case of 1, it increased about 4 times. This means that even if the fan wind speed is increased to 8 m / sec, the moisture content of the dehydrated cake can be easily reduced, but a more remarkable effect commensurate with the economy cannot be expected. .

  On the other hand, in the case of Comparative Example 1, since the fan wind speed was set to 0.5 m / second, which was not specified, the moisture content was 24.9% by mass (decrease rate of 12%), and the moisture content was not sufficiently reduced. I understand that there was. Further, in the case of Comparative Example 2, since the intermittent operation was performed for 1 minute and stopped for 3 minutes, and the residence time of the dehydrated cake was set to 16 minutes which was not specified, the moisture content was 26.1% by mass (a decrease rate of 8%) It can be seen that the moisture content was not sufficiently reduced. Furthermore, in the case of Comparative Example 3 (in the case of intermittent operation of 1 minute operation, 29 minute stop and when the dewatered cake residence time is set to 120 minutes which is not specified), the same result as in Example 5 is obtained. However, it can be seen that the size of the conveyor is about twice as large as that in Example 1, which is not preferable.

DESCRIPTION OF SYMBOLS 1 Dewatered cake 2 Conveyor 3 Windshield cover 4 Fan 5 Windshield curtain 6 Outside air 7 Dehydrated cake accumulation place 8 Blowing direction 10 Dehydrated cake moisture content reducing device 20 Dehydrator 31 Inlet end 32 Outlet end 51 Opening notch

Claims (6)

A conveyor that conveys the dewatered cake formed by discharging the excess sludge of the coagulation sedimentation process after being dewatered by the dehydrator;
A cylindrical windshield cover covering at least the upper part of the conveyor;
Provided near the entrance end of the windshield cover, and a fan that blows air to the dewatered cake to be conveyed,
The conveyor is configured so that the residence time of the dehydrated cake to be conveyed is 45 to 90 minutes,
The fan is configured so that the air blown to the dehydrated cake is performed at room temperature at a wind speed of 2 m / second or more and in the windshield cover in a direction from the inlet end to the outlet end. The reduction rate of the moisture content of the dehydrated cake before and after the treatment [{(water content at the inlet end−water content at the outlet end) / (water content at the inlet end)} × 100] is 15% or more. An apparatus for reducing the moisture content of a dehydrated cake,   The dehydrating cake moisture content reducing device according to claim 1, wherein the dehydrated cake has a pellet shape or a lump shape with a thickness of 10 to 50 mm.   The windshield cover has a windshield curtain at the entrance end, and the windshield curtain can introduce a dehydrated cake at a position in contact with the conveyor, and the dehydrated cake piled up and stacked on the conveyor is uniform. The dehydrating cake moisture content lowering device according to claim 1 or 2, further comprising an opening notch for spreading uniformly. The dewatered cake formed by discharging the excess sludge from the coagulation sedimentation process after being dehydrated by the dehydrator is loaded on a conveyor whose upper part is covered with a cylindrical windshield cover, Conveying with a residence time of 45 to 90 minutes;
For the dewatered cake loaded and transported on the conveyor, a fan provided near the inlet end of the windshield cover is used at a wind speed of 2 m / second or more at room temperature and in the windshield cover. , In the direction from the inlet end toward the outlet end, and the rate of decrease in the moisture content of the dehydrated cake before and after the blowing treatment [{(moisture content at the inlet end−moisture content at the outlet end) / (inlet end] The method of reducing the moisture content of a dehydrated cake is characterized by comprising: a step of blowing air so that the water content of}} 100] is 15% or more.   The method for lowering the water content of a dehydrated cake according to claim 4, wherein the dehydrated cake has a pellet shape or a lump shape with a thickness of 10 to 50 mm.   The windshield cover has a windshield curtain at the entrance end, and the windshield curtain can introduce a dehydrated cake at a position in contact with the conveyor, and the dehydrated cake piled up and stacked on the conveyor is uniform. The method for lowering the moisture content of a dehydrated cake according to claim 4 or 5, further comprising an opening notch for uniformly spreading the cake.

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