JP7491083B2 - Ash disposal method - Google Patents

Description

The present invention relates to an ash processing method.

Conventionally, a treatment method is known in which waste such as coal ash is poured into a storage area where water is stored and treated. For example, Patent Documents 1 to 4 describe this type of technology. Patent Document 1 describes a method of dumping coal ash slurry, which is made by adding a surfactant to coal ash, into water. Patent Document 2 describes a method of discharging coal ash slurry from a slurry outlet into a recess, and allowing a portion of the discharged coal ash slurry to flow along a groove, causing the coal ash to settle in the groove. Patent Document 3 describes a treatment method in which a water reservoir is formed on the upper surface of the landfilled incineration ash, and water is sealed in the water reservoir so that water always accumulates in the water reservoir. Patent Document 4 describes dividing the interior of the landfill into a number of sections, and discharging waste including organic waste into each section.

Japanese Patent Application Laid-Open No. 62-91284 JP 2019-118865 A JP 2003-290737 A Japanese Patent Application Laid-Open No. 60-112908

In the coal ash treatment methods described in Patent Documents 1 and 2, water is constantly stored in the storage section to prevent the input coal ash from scattering. However, if the water level in the storage section rises due to rainwater or the like, the water must be discharged to the outside to adjust the water level. However, since the water in the storage section contains coal ash, drainage treatment is required to discharge the water to the outside, and adjusting the water level is costly. Patent Document 3 describes a method for removing salts from a landfill site where landfilling has already been completed, but does not describe the process of sending coal ash to the storage section and filling it in. The method in Patent Document 4 can reduce the concentration and amount of sludge materials in the surplus water and leachate, but ultimately requires drainage treatment to discharge the water to the outside.

The present invention aims to provide an ash treatment method that can reduce the cost of adjusting the water level in the storage section while preventing coal ash from scattering.

The present invention relates to an ash processing method for processing coal ash in a storage section where water is stored, the ash processing method including a structure forming step of forming a structure in the storage section, which is made of solidified coal ash and which sucks up water from a submerged section located below the water surface and evaporates it from an exposed section located above the water surface, and an ash transport step of transporting coal ash to the storage section where the structure is formed and water is stored.

In the structure formation process, the structure is formed so that the area between one bank and the other bank of the storage section is divided into multiple areas, and in the ash transfer process, coal ash is sent from the area on one side of the storage section, and after that area is filled with coal ash, the transfer of coal ash to the adjacent area on the other side is started.

In the structure formation process, a plurality of structures are formed in the storage section, extending radially from a predetermined location in the storage section, forming a plurality of flow paths partitioned by the structures, and in the ash transport process, the coal ash is sent to the predetermined location.

The present invention provides an ash treatment method that can prevent coal ash from scattering while reducing the cost of adjusting the water level in the storage section.

1 is a side view showing an ash processing facility in which an ash processing method according to a first embodiment of the present invention is used. FIG. 1 is a plan view showing an ash processing facility in which an ash processing method according to a first embodiment of the present invention is used. FIG. FIG. 2 is a side view showing how coal ash is treated by the ash treatment method according to the first embodiment of the present invention. FIG. 2 is a perspective view showing an ash processing facility in which an ash processing method according to a second embodiment of the present invention is used. FIG. 13 is a diagram showing the evaluation results of the water evaporation promoting effect of solidified coal ash. FIG. 13 is a diagram showing the evaluation results of the water evaporation promoting effect of solidified coal ash.

Below, preferred embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

The ash processing method according to the first embodiment is a method for processing coal ash generated from coal-fired power plants and the like. First, an ash processing facility 1 in which the ash processing method according to this embodiment is used will be described with reference to Figures 1 and 2. Figure 1 is a side view of the ash processing facility 1 in which a structure 30 is formed, and Figure 2 is a plan view of the ash processing facility 1 in which a structure 30 is formed.

As shown in Figures 1 and 2, the ash treatment equipment 1 includes a storage section 10, a transfer pipe 20, and a structure 30 formed in the storage section 10.

The storage area 10 is an area where coal ash 3 is placed and filled. Water is stored in the storage area 10 to prevent the coal ash 3 from scattering. In this embodiment, the storage area 10 is a part of the sea or lake surrounded by land 2 and a dike 4.

The transfer pipe 20 is a pipe for transferring coal ash 3 from a coal ash 3 supply source (not shown) to the storage section 10. The transfer pipe 20 is provided above the storage section 10 and extends from the land 2, which is the shore on one side (the left side in Figs. 1 and 2) of the storage section 10, to the embankment 4, which is the shore on the other side (the right side in Figs. 1 and 2). A supply source of coal ash 3 is provided on the one side where the land 2 is located. The coal ash 3 flows through the transfer pipe 20 in the form of a slurry mixed with water, and is sent to the storage section 10 from a delivery outlet 21 provided at the tip of the transfer pipe 20.

The structure 30 is made of solidified coal ash 3. The solidified coal ash 3 is made by solidifying the coal ash using a solidifying material such as cement, and has pores on its surface. The structure 30 is formed so as to stand upright from the bottom of the storage section 10.

The structure 30 has a submerged portion 31 located below the water surface of the storage portion 10 and an exposed portion 32 located above the water surface. The structure 30 evaporates water drawn up from the submerged portion 31 through the exposed portion 32. Specifically, the water in the storage portion 10 is drawn up by capillary action through pores on the surface of the submerged portion 31 located below the water surface, and is discharged as steam V from the exposed portion 32 exposed above the water surface of the storage portion 10. This promotes evaporation of the water in the storage portion 10, thereby suppressing the rise in the water level of the storage portion 10 due to rainwater, etc.

In this embodiment, the area between the land 2 on one side of the storage section 10 and the embankment 4 on the other side is divided into multiple areas by forming two structures 30, structures 30a and 30b. As shown in FIG. 1, structures 30a and 30b are formed with a gap between them. Structure 30a is located on one side of structure 30b. Structures 30a and 30b divide the storage section 10 into a landfill area 11 formed between the land 2 and structure 30a, a landfill area 12 formed between structures 30a and 30b, and a landfill area 13 formed between structure 30b and the embankment 4.

As shown in FIG. 1, the bottom of the storage section 10 is formed so that it is positioned lower from one side to the other. Specifically, the bottom of the landfill area 12 is positioned lower than the bottom of the landfill area 11, and the bottom of the landfill area 13 is positioned lower than the bottom of the landfill area 12.

Next, the ash treatment method according to the first embodiment will be described with reference to FIG. 3. FIG. 3(A) is a diagram showing the state in which a structure 30 has been formed in the storage section 10, FIG. 3(B) is a diagram showing how coal ash 3 is sent to the landfill area 11, FIG. 3(C) is a diagram showing how coal ash 3 is sent to the landfill area 12, and FIG. 3(D) is a diagram showing how coal ash 3 is sent to the landfill area 13.

The ash treatment method according to this embodiment includes a structure formation process for forming a structure 30 in the storage section 10, and an ash transport process for transporting coal ash 3 to the storage section 10 in which the structure 30 has been formed and water has been stored.

In the structure formation process, as shown in FIG. 3(A), structures 30a and 30b are formed so that three areas are partitioned between land 2 on one side of storage section 10 and embankment 4 on the other side. Structures 30a and 30b partition storage section 10 into landfill area 11, landfill area 12, and landfill area 13.

In the structure formation process of this embodiment, the bottom of the landfill area 12 is formed to be located lower than the bottom of the landfill area 11, and the bottom of the landfill area 13 is formed to be located lower than the bottom of the landfill area 12. Therefore, for example, as shown in FIG. 3(A), the water level of the landfill area 12 can be adjusted to a lower position relative to the structure 30a, so that the surface area of the other side of the exposed portion 32 of the structure 30a becomes larger. Therefore, even if the water level of the landfill area 11 on one side of the structure 30a is high, the high water evaporation promotion effect of the structure 30a can be maintained.

In the ash transfer process, structures 30a and 30b are formed, and coal ash 3 is transferred to the storage section 10 in which water is stored. In the ash transfer process of this embodiment, coal ash 3 is transferred from the landfill area 11 on one side of the storage section 10, and after the landfill area 11 is filled with coal ash 3, transfer of the coal ash 3 to the adjacent landfill area 12 on the other side is started.

First, as shown in FIG. 3(B), slurry-like coal ash 3 is sent to the landfill area 11 from the delivery port 21 of the transfer pipe 20 located above the landfill area 11. At this time, water is appropriately supplied so that the landfill area 11 is kept filled with water.

After filling the landfill area 11 with coal ash 3 up to the height of the structure 30a, the coal ash 3 is covered with soil 5 to prevent the coal ash 3 from scattering, and the landfilling of the landfill area 11 is completed.

As shown in FIG. 3(C), after filling the landfill area 11 with coal ash 3, the transfer pipe 20 is extended so that the outlet 21 of the transfer pipe 20 is located above the landfill area 12. The slurry-like coal ash 3 is then sent from the outlet 21 to the landfill area 12. At this time, water is supplied appropriately so that the landfill area 12 remains water-filled.

After filling the landfill area 12 with coal ash 3 up to the height of the structure 30b, the landfilling of the landfill area 12 is completed by covering the coal ash 3 with soil 5.

As shown in FIG. 3(D), after the landfill area 12 is filled, the transfer pipe 20 is extended so that the outlet 21 of the transfer pipe 20 is located above the landfill area 13. Then, the slurry-like coal ash 3 is sent from the outlet 21 to the landfill area 13. At this time, water is supplied appropriately so that the landfill area 13 is kept filled with water.

After filling the landfill area 13 with coal ash 3 to a specified height, the landfilling of the landfill area 13 is completed by covering the coal ash 3 with soil 5. As a result, the entire storage section 10 is filled with coal ash 3, and the ash processing work is completed.

In order to prevent the coal ash 3 from scattering, it is necessary to constantly store water in the storage section 10 to which the coal ash 3 is sent. If the water level drops, water can be added to the storage section 10. However, if the water level rises, the coal ash 3 is contained in the water in the storage section 10, so it is necessary to carry out drainage treatment to discharge the water to the outside, and adjusting the water level is costly.

In this embodiment, water can be sucked up from the immersed portion 31 and the evaporation of the water can be promoted in the exposed portion 32, and the rise in the water level in the storage portion 10 can be suppressed. Therefore, the cost of adjusting the water level in the storage portion 10 where water is stored can be suppressed.

In addition, in this embodiment, the storage section 10 is divided into a plurality of landfill areas 11, 12, and 13 by forming the structure 30, and coal ash 3 is sent to each of the landfill areas 11, 12, and 13. As a result, even if coal ash 3 is sent from one location, it is easier to distribute the coal ash 3 so that it reaches the entire divided landfill areas 11, 12, and 13, compared to when the storage section 10 is not divided.

In addition, in this embodiment, after the landfilling of one side of the storage section 10 is completed, the transfer of coal ash to the adjacent area on the other side begins. Therefore, for example, as the accumulation of coal ash 3 in the landfill area 11 progresses, the area of the exposed portion 32 on one side of the structure 30a decreases, but the area of the exposed portion 32 on the other side of the structure 30a located above the water surface in the landfill area 12 does not change. Therefore, even if the accumulation of coal ash 3 in the landfill areas 11 and 12 progresses, the rise in the water level of the storage section 10 can be kept suppressed.

Next, an ash processing facility 1A using an ash processing method according to the second embodiment will be described with reference to FIG. 4. FIG. 4 is a perspective view showing the vicinity of the discharge port 21 of the transfer pipe 20 of the ash processing facility 1A in which a structure 30 is formed. Note that configurations similar to those in the first embodiment may be assigned the same reference numerals and descriptions thereof may be omitted.

The ash treatment facility 1A includes a storage section 10, a transfer pipe 20, and eight (multiple) structures 30 made of coal ash 3. The main difference between the ash treatment facility 1A and the other facilities is the arrangement of the transfer pipes 20 and the structures 30.

The transfer pipe 20 is provided above the storage section 10 and extends from one side of the storage section 10 where the coal ash 3 supply source is located toward the center of the storage section 10. In this embodiment, the delivery port 21 of the transfer pipe 20 is located approximately at the center of the storage section 10 in a plan view.

The structure 30 of this embodiment is made of solidified coal ash 3, similar to the structure 30 of the first embodiment, and has pores on its surface. The structure 30 is also formed in the storage section 10, and has a submerged section 31 located below the water surface and an exposed section 32 located above the water surface, and water sucked up from the submerged section 31 is evaporated from the exposed section 32.

In this embodiment, the reservoir 10 is partitioned to form channels 15a to 15h by forming eight structures 30, 30c to 30j, that extend radially from a predetermined point. Specifically, channel 15a is formed between structures 30c and 30d, channel 15b is formed between structures 30d and 30e, channel 15c is formed between structures 30e and 30f, channel 15d is formed between structures 30f and 30g, channel 15e is formed between structures 30g and 30h, channel 15f is formed between structures 30h and 30i, channel 15g is formed between structures 30i and 30j, and channel 15h is formed between structures 30j and 30a.

The specified location is located below the discharge port 21 and is the inlet 14 through which the coal ash 3 flows into the storage section 10. The inlet 14 is located approximately at the center of the storage section 10 in a plan view. The structures 30c to 30j are spaced equally apart in the circumferential direction in a plan view. The flow paths 15a to 15h are connected to each other via the inlet 14.

Next, the ash processing method according to the second embodiment will be described. The ash processing method according to this embodiment includes a structure formation process for forming the structure 30, and an ash transfer process for transferring the coal ash 3 to the storage section 10 in which the structure 30 has been formed and in which water has been accumulated.

In the structure formation process, as shown in FIG. 4, structures 30c to 30j are formed in the storage section 10, extending radially from the inlet section 14 of the storage section 10, thereby forming flow paths 15a to 15h partitioned by the structures 30c to 30j.

In the ash transfer process, coal ash 3 is sent from the outlet 21 of the transfer pipe 20 located above the storage section 10 to the inlet section 14 of the storage section 10. The coal ash 3 sent to the inlet section 14 is dispersed in eight directions from the inlet section 14 and flows into the flow paths 15a to 15h.

After filling the entire storage section 10 with coal ash 3 up to a specified height, the coal ash 3 is covered with soil, filling the entire storage section 10 with coal ash 3 and completing the ash processing work.

In this embodiment, the structures 30c to 30j are formed radially from the inlet 14, so that the coal ash 3 can be smoothly sent to the storage section 10 without being impeded by the structures 30a to 30j while the rise in the water level in the storage section 10 is more reliably suppressed by the structures 30a to 30j. The coal ash 3 can be made to flow into the multiple flow paths 15a to 15h from the inlet 14 located approximately in the center of the storage section 10, so that the entire storage section 10 can be filled without changing the position where the coal ash 3 flows into the storage section 10.

Next, an evaluation test of the water evaporation promotion effect of the solidified coal ash 3 will be described. The following test was conducted using solidified coal ash 3 to confirm the water evaporation promotion effect of the structure 30.

The test method will be explained. Sample A was created by placing multiple spherical coal ash solids in a container with a diameter of approximately 9 cm, and filling the container with water so that the water level was 12.3 cm high, immersing the coal ash solids. Sample B was also created by filling a container with approximately 9 cm diameter with water only, without any coal ash solids, so that the water level was 12.3 cm high. Samples A and B were then left to stand indoors, and the amount of water in each container was measured after approximately 1.7 days, 2.8 days, 6.8 days, 10.7 days, and 18.9 days.

Sample C was created by placing multiple spherical coal ash solids in a container with a diameter of approximately 9 cm, similar to sample A, and immersing the coal ash solids in water so that the water level in the container was 12.3 cm high. Sample D was created by placing no coal ash solids in a container with a diameter of approximately 9 cm, similar to sample B, but only filling it with water so that the water level was 12.3 cm high. Samples C and D were then left to stand indoors, and the amount of water in each container was measured after approximately 9.1 days and 15.8 days. Evaluation tests using samples C and D were conducted to confirm the reproducibility of the evaluation tests using samples A and B.

The test results are explained. Figure 5 shows the progress of the decrease in the amount of water in the containers of Sample A and Sample B. The horizontal axis of Figure 5 shows the number of days since the start of the evaluation, and the vertical axis shows the water level (cm) in the container on each measurement day. As shown in Figure 5, it can be confirmed that the amount of water in the container of Sample A, in which the solidified coal ash was immersed, decreases faster than that of Sample B, in which the solidified coal ash was not immersed. Specifically, after about 1.7 days, the amount of water in Sample B decreased by less than about 0.5 cm, while the amount of water in Sample A decreased by about 2 cm. Furthermore, after about 18.9 days, the amount of water in Sample B decreased by less than half of the amount at the start of the test, while the amount of water in Sample A decreased by more than 10 cm.

Figure 6 shows the amount of water in the containers of Samples C and D on each of the above measurement dates. The horizontal axis of Figure 6 shows the number of days elapsed since the start of the evaluation, and the vertical axis shows the water level height (cm) in the container on each measurement date. As shown in Figure 6, it was confirmed that, like Samples A and B, the amount of water in the container of Sample C, which was immersed in solidified coal ash, decreased more quickly than Sample D, which was not immersed in solidified coal ash. From the results of Samples A to D, it is believed that the solidified coal ash promoted the evaporation of water in the container.

The ash processing method according to the embodiment described above provides the following advantages:

The ash processing method according to an embodiment of the present invention is an ash processing method for processing coal ash 3 in a storage section 10 in which water is stored, and includes a structure formation step of forming a structure 30 in the storage section 10, which is made of solidified coal ash 3 and which evaporates water sucked up from a submerged section 31 located below the water surface from an exposed section 32 located above the water surface, and an ash transport step of transporting the coal ash 3 to the storage section 10 in which the structure 30 has been formed and in which water is stored.

As a result, the structure 30 promotes the evaporation of water, suppressing the rise in the water level in the storage section 10, and avoiding the situation in which water containing coal ash 3 must be drained and discharged outside the storage section 10 to adjust the water level even when it rains. This prevents the coal ash 3 from scattering, while reducing the cost of adjusting the water level in the storage section 10 to which the coal ash 3 is sent. In addition, because the structure 30 is established using the coal ash 3 to be treated, the cost of raw materials and other costs required for forming the structure 30 can also be reduced.

In the ash processing method according to an embodiment of the present invention, in the structure formation process, structures 30a and 30b are formed so that the area between one bank and the other bank of the storage section 10 is divided into multiple landfill areas 11, 12, and 13, and in the ash transfer process, coal ash 3 is transferred from the landfill area 11 on one side of the storage section 10, and after the landfill area 11 is filled with coal ash 3, transfer of the coal ash 3 to the adjacent landfill area 12 on the other side is started.

As a result, even if the area of the exposed portion 32 on one side of the structure 30a decreases as the coal ash 3 in the landfill area 11 accumulates, the area of the exposed portion 32 on the other side of the structure 30a located above the water surface in the landfill area 12 does not change. Therefore, even if the coal ash 3 accumulates, the high water evaporation promotion effect of the structures 30a and 30b can be maintained, so that the reservoir 10 can be filled in more reliably while suppressing the rise in the water level. In addition, since the reservoir 10 is divided into small landfill areas 11, 12, and 13, and the landfill areas 11 and 12 where landfilling is completed can be used as footing, management of the reservoir 10 becomes easier and the work and structure for draining the water in the reservoir 10 can be omitted.

In the ash processing method according to an embodiment of the present invention, in the structure formation process, a plurality of structures 30 are formed in the storage section 10, extending radially from the inlet section 14 of the storage section 10, to form a plurality of flow paths 15a-15h partitioned by the plurality of structures 30, and in the ash transport process, coal ash is sent to a predetermined location.

As a result, the multiple structures 30 are formed radially from the inlet section 14, so that the coal ash 3 can be sent to the inlet section 14 without being hindered by the multiple structures 30, and the coal ash 3 can flow from the inlet section 14 to the multiple flow paths 15a to 15h. Therefore, the multiple structures 30 can more reliably suppress the rise in the water level in the storage section 10, while the coal ash 3 can be smoothly sent to the entire storage section 10 without changing the position where it flows into the storage section 10.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be modified as appropriate.

In the above embodiment, after filling the storage section 10 with coal ash 3, the storage section 10 is covered with soil as a post-treatment, but the method of post-treatment is not particularly limited as long as it is possible to prevent the coal ash 3 from scattering. For example, a net with plant seeds may be laid on top of the filled coal ash 3, or solidified coal ash 3 may be laid.

The embankment 4 in the above embodiment may be constructed of a structure 30 made of solidified coal ash 3. This makes it possible to more reliably prevent the water level in the entire reservoir 10 from rising.

REFERENCE SIGNS LIST 1, 1A Ash treatment facility 3 Coal ash 10 Storage section 30 Structure 31 Submerged section 32 Exposed section

Claims (2)

An ash processing method for processing coal ash in a reservoir in which water is stored, comprising the steps of:
a structure forming step of forming a structure in the storage section, the structure being made of solidified coal ash and configured to evaporate water sucked up from a submerged portion located below the water surface through an exposed portion located above the water surface;
an ash transporting step of transporting coal ash to the storage section in which the structure is formed and water is stored;
Including,
In the structure forming step, a plurality of the structures are formed in the storage section, the structures extending radially from a predetermined location of the storage section as a center, thereby forming a plurality of flow paths partitioned by the plurality of the structures;
In the ash transporting step, the coal ash is transported to the predetermined location . In the structure forming step, the structure is formed so that an area between one bank and the other bank of the storage section is divided into a plurality of regions;
2. The ash processing method according to claim 1, wherein in the ash transporting step, coal ash is transported from an area on one side of the storage section, and after that area is filled with coal ash, transport of the coal ash to an adjacent area on the other side is started.

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