JP2024018336A - Drying method and device for liquid-containing materials - Google Patents

Abstract

The present invention provides a method and apparatus for drying a liquid-containing material that can efficiently dry the liquid-containing material. [Solution] A method for drying a slurry-like or paste-like liquid-containing material containing a liquid and particles, including an adhesion step of adhering the liquid-containing material to a planar part of a planar part-equipped body, and then drying. A method for drying a liquid-containing material, comprising the steps of: A method for drying a liquid-containing material, further comprising, after the adhering step, a liquid-draining step of removing the liquid-containing material adhering to the planar portion. In the drying step, room temperature or heated gas is passed along the surface of the liquid-containing material attached to the planar portion to dry it. [Selection diagram] Figure 1

Description

The present invention relates to a method and apparatus for drying a liquid-containing material (or a water-containing material when the liquid is water), and more particularly to a method and apparatus for drying a liquid-containing material in the form of a slurry, paste, or the like. One aspect of the present invention is the drying of various types of sludge discharged from water treatment processes, that is, the drying of water-containing substances such as sedimentation recoveries, filtration recoveries, flocculation-treated sludge, and biologically-treated sludge, or the drying of liquids and solids in various manufacturing processes. The present invention relates to a method and apparatus suitable for drying liquid-containing waste containing organic substances, or drying liquid-containing substances such as fermentation residues of organic substances.

As a method for drying sludge, Patent Document 1 describes that sludge is washed, then dehydrated, and then dried with warm air.

Patent Document 2 describes that sludge fragments are dried while being moved within a drying chamber.

Patent Document 3 describes that sludge treated with a dehydrator having a gravity filtration section and a dewatering section is cut into pieces and dried.

Japanese Patent Application Publication No. 2000-263098 Japanese Patent Application Publication No. 2009-101276 Japanese Patent Application Publication No. 2016-209814

It is well known that a large amount of energy is required to evaporate water. In addition, water-containing materials such as biologically treated sludge are simply water-containing due to hydration between water and solids, the presence of proteins or carbohydrates that hold water, or the presence of flocculants that hold water. It is more difficult than vaporizing molecules. Therefore, water-containing substances are very difficult to dry, and even with the methods of Patent Documents 1 to 3, it is not easy to sufficiently evaporate water and dry them.

The factors involved in drying are temperature (heat), humidity (saturated water vapor pressure), and the expected flow (wind force, wind speed) to quickly move the water vapor saturated layer at the interface between water and gas. It is. The present invention provides a method and apparatus for efficiently drying a liquid-containing material by skillfully combining and controlling the factors involved in water evaporation.

[1] A method for drying a slurry-like or paste-like liquid-containing material containing a liquid and particles,
1. A method for drying a liquid-containing material, the method comprising: an adhering step of adhering the liquid-containing material to a planar part of a planar part-equipped body; and a drying step of drying thereafter.

[2] The method for drying a liquid-containing material according to [1], wherein the planar portion has a slit-like gap.

[3] The method for drying a liquid-containing material according to [1], wherein the planar portion has a mesh shape.

[4] The method for drying a liquid-containing material according to [1], wherein the planar portion has irregularities.

[5] The method for drying a liquid-containing material according to [1], further comprising, after the adhering step, a liquid-draining step of removing the liquid-containing material adhering to the planar portion.

[6] The method for drying a liquid-containing material according to [5], in which the liquid-draining step is carried out by placing the liquid-containing material-adhering surface portion-equipped body in an upright state.
[7] The method for drying a liquid-containing material according to [6], wherein in the liquid-draining step, heat is applied to the liquid-containing material adhering to the planar portion so that it can be maintained at a desired temperature.

[8] The method for drying a liquid-containing material according to [1], wherein in the drying step, drying is carried out by flowing room temperature or heated gas along the surface of the liquid-containing material attached to the planar portion.

[9] The method for drying a liquid-containing material according to [8], wherein in the drying step, the flow rate and/or direction of the gas is changed.

[10] The method for drying a liquid-containing material according to [9], wherein the drying step is performed with the liquid-containing material-adhering surface portion-equipped body in an upright state.

[11] The method for drying a liquid-containing material according to [10], wherein in the drying step, the upright angle of the liquid-containing material-adhering surface portion-equipped body is changed.

[12] The method for drying a liquid-containing material according to [9], wherein in the drying step, the vertical direction of the liquid-containing material-attached surface portion-equipped body is reversed.

[13] In an apparatus for drying a liquid-containing substance in the form of a slurry or paste containing a liquid and particles, an adhering means for adhering the liquid-containing substance to a planar part of a planar part-equipped body, and a drying means for drying the liquid-containing substance thereafter. A drying device for a liquid-containing material, comprising:

[14] The drying device for a liquid-containing material according to [13], wherein the planar portion has a slit-like gap.

[15] The liquid-containing material drying device according to [13], wherein the planar portion has a mesh shape.

[16] The drying device for a liquid-containing material according to [13], wherein the planar portion has irregularities.

[17] The apparatus for drying a liquid-containing material according to [13], further comprising a liquid draining means for draining the liquid-containing material adhering to the planar portion.

[18] The apparatus for drying a liquid-containing material according to [17], further comprising a raising means for raising the liquid-containing material-adhering surface portion device into an upright state.

[19] The apparatus for drying a liquid-containing material according to [18], further comprising means for applying heat so that the liquid-containing material attached to the planar portion can be maintained at a desired temperature.

[20] The apparatus for drying a liquid-containing material according to [13], wherein the drying means is a means for drying the liquid-containing material by flowing room temperature or heated gas along the surface of the liquid-containing material attached to the planar portion.

[21] The apparatus for drying a liquid-containing material according to [20], comprising means for changing the flow rate and/or direction of the gas.

[22] The apparatus for drying a liquid-containing material according to [21], further comprising a raising means for raising the liquid-containing material-adhering surface portion device into an upright state.

[23] The apparatus for drying a liquid-containing material according to [22], further comprising means for changing the upright angle of the liquid-containing material-adhering surface-like member.

[24] The apparatus for drying a liquid-containing material according to [22], further comprising means for reversing the vertical direction of the liquid-containing material-adhering surface portion-equipped body.

According to the present invention, even a liquid-containing substance that is difficult to dry, such as a slurry or a paste, can be adhered to the planar portion of the planar portion-equipped body and can be efficiently dried.

It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. It is a block diagram of a planar part concrete body. FIG. 3 is an explanatory diagram of a method for forming a deposit layer. FIG. 3 is an explanatory diagram of a method for forming a deposit layer. FIG. 3 is an explanatory diagram of a method for forming a deposit layer. It is a block diagram of a frame-shaped holder and a planar part provision body. It is a block diagram of a frame-shaped holder and a planar part provision body. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. It is an explanatory view of a draining method. FIG. 3 is an explanatory diagram of a drying method. FIG. 3 is an explanatory diagram of a drying method. FIG. 3 is an explanatory diagram of a drying method. FIG. 3 is an explanatory diagram of a drying method. FIG. 3 is an explanatory diagram of a drying method. FIG. 3 is an explanatory diagram of a drying method. It is an explanatory view of an experimental example of draining. It is a graph showing the experimental results of draining. It is a graph showing the experimental results of draining. It is a graph showing the experimental results of draining.

The present invention will be explained in more detail below.

[Liquid-containing material]
In the present invention, the liquid-containing material to be dried is in the form of a slurry or paste. The term "slurry" as used herein refers to a liquid-containing material in which solids are suspended in a liquid. Paste refers to a liquid-containing material that has fluidity but higher viscosity than slurry. Specific examples of liquid-containing substances include biologically treated sludge from wastewater, especially wastewater containing organic matter, sludge and floating scum generated in wastewater treatment processes, as well as methane fermentation, alcohol fermentation, lactic acid fermentation, hydrogen fermentation, oxidative fermentation, Examples include, but are not limited to, hydrated substances such as residues generated in acetone-butanol fermentation or residues discharged during soy sauce or soy milk production. The liquid-containing substance may be a non-aqueous liquid-containing substance that contains a solid substance and a non-aqueous liquid such as oil or an organic solvent other than water, and is in the form of a slurry or paste. It may be a liquid-containing material in the form of a slurry or a paste.

[Plane-like part-equipped body]
In the present invention, a liquid-containing substance is attached to a planar part of a planar part-equipped body and then dried. The planar portion may be any shape that extends two-dimensionally, such as a plate shape, a sheet shape, a net shape, a cloth (particularly a woven cloth), a screen shape, or the like. The planar portion may have a planar shape or may have a curved surface shape such as a corrugated plate shape.

Suitable planar portions include screen-like ones, nets, woven fabrics, non-woven fabrics, and water-permeable films. As the screen-like surface portion, a screen-like structure in which elongated rod-like bodies are arranged in parallel and connected with a binding material such as a string is suitable. This rod-shaped body may be either a round rod shape or a square rod shape, but a round rod shape with a circular cross section is preferable.

The material for the planar parts such as rods and binding materials is preferably synthetic resin in view of water absorption properties, corrosion, and salt precipitation problems. As the synthetic resin, it is preferable to select and use one having excellent properties such as water resistance, heat resistance, and weather resistance.

When the planar portion is plate-shaped or sheet-shaped, a large number of holes may be provided that penetrate the planar portion in the thickness direction. The greater the number of pores, the better the water permeability, but there is a risk of solids flowing out. It is desirable that there be at least one hole approximately every 1 cm square. There is no restriction on the shape of the hole, and it may be polygonal, circular, or complex. On the other hand, the diameter of the hole needs to be adjusted according to the condition of the material to be dried. If the pores are too large, solids may flow out, and if the pores are close to the size of the solids, the pores may become clogged with solids. If the pores are too small, it will take time for liquid to pass through, resulting in poor permeability. In view of liquid permeability, the pore diameter or pore width is preferably about 0.1 mm to 10 mm, especially about 0.5 to 5 mm, and the center pore diameter and pore diameter range should be determined appropriately depending on the condition of the material to be dried. It's better to design.

The planar portion-equipped body may consist of only a planar portion, or may have a frame portion provided around the entire circumference of the planar portion or on a pair of parallel sides.

The planar portion-equipped body may be shaped like a container, and the bottom surface of the container may be the planar portion.

An example of a body with a planar portion is shown in FIGS. 1 to 8.

FIG. 1 shows a planar part-equipped body 1 consisting of a simple flat tray (18 cm x 30 cm) with no holes in the bottom plate. Note that (b) is a sectional view taken along the line BB in (a).

FIG. 2 shows a planar part-equipped body 2 consisting of a tray using a punching plate having a large number of holes 2a in the bottom plate. Note that (b) is a view taken along the line BB in (a).

FIG. 3 shows a planar part-equipped body 3 made of a plate with a slit 3a having a width that allows liquid to pass through the bottom plate. Note that (b) is a view taken along the line BB in (a).

FIG. 4 shows a net-like sheet-like part-equipped body 4 made by connecting bamboo strips like a raft. Note that (b) is a view taken along the line BB in (a).

FIG. 5 shows a screen girder-shaped planar part-equipped body 5 made using a net (for screen doors, for example, 18 mesh) 5a. Note that (b) is a sectional view taken along the line BB in (a). Although not shown in the drawings, the net 5a may be replaced by a filter cloth for a dehydrator (made of polypropylene, plain weave) or a screen girder made of a water-permeable nonwoven fabric sheet.

The sheet-like portion-equipped body may be a sheet-like portion-equipped body 5' made by stretching a water-permeable film 5f on a wire mesh 5m instead of the net 5a, as shown in FIG. 5(c).

FIG. 6 shows a planar portion-equipped body 6 made of a plate having an uneven (comb-shaped) surface. Note that (b) is a view taken along the line BB in (a).
By forming the concave portion, a space is created for the liquid to seep out, and the removal of the liquid can be further enhanced in the subsequent liquid draining step, especially when the surface-shaped portion-equipped body is stood up to drain the liquid.

FIG. 7 shows a planar part-equipped body 7 made of a plate having unevenness (triangular protrusions) on its surface. Note that (b) is a view taken along the line BB in (a).
The expected effect is the same as that of unevenness (triangular protrusions), but because the flow of gas on the slope during drying becomes smoother, it can be expected to have the effect of further increasing the removal efficiency of the vapor-saturated layer.

FIG. 8 shows a planar portion-equipped body 8 made of a plate having an uneven (wavy) surface. Note that (b) is a view taken along the line BB in (a).

[Method of attaching a liquid-containing substance to a planar part-equipped body]
In order to attach the liquid-containing substance to the sheet-like portion-equipped body, the liquid-containing substance may be applied by painting or may be applied by spraying. If the liquid-containing material is highly fluid, such as liquid, the liquid-containing material may be strained and attached to the surface-shaped member, or the liquid-containing material may be poured into the surface-shaped member and filtered. It may also be attached.

After the liquid-containing material is deposited on the planar portion-equipped body, the upper surface of the deposit may be leveled.

The preferred thickness of deposits when flattened varies depending on the nature of the liquid-containing material, but in the case of biological treatment sludge and fermentation residue, if the thickness is too large, the drying time will be long; If this is the case, the filling efficiency will be low and the volumetric efficiency will be poor, so the thickness at the time of drying is preferably about 0.1 to 20 mm, particularly about 1 to 5 mm.

The liquid-containing material may be applied to the entire surface of the surface, or may be applied only to a portion of the surface of the surface excluding the peripheral edge. In the latter case, it is preferable that the distance between the liquid-containing substance adhesion region and the peripheral edge of the planar portion be 30 cm or less, more preferably 10 cm or less.

Specific examples of the manner in which the liquid-containing material is attached to the planar portion-equipped body are shown in FIGS. 9 to 11.

FIG. 9 shows a method for attaching a liquid-containing material by straining the slurry-like liquid-containing material onto a surface-like member. As shown in the figure, a mold 11 is placed on the planar part-equipped body 10, and the liquid-containing material 13 in the tank 12 is poured out into the mold 11 to form a deposit layer of the liquid-containing material 13. In addition, in the tank 12, the material to be dried (sludge slurry, etc.) and a flocculant may be mixed to form an aggregate. In this case, although not shown, the tank 12 is equipped with stirring blades. In addition, when the material to be dried and the flocculant are poured into the tank 12, the pouring force and flow rate may be used to mix them. For example, both can be dropped at the same time and mixed by the rupture and diffusion force resulting from the impact, or they can be ejected toward the inner wall to create a swirling flow and mix.

The mold 11 moves downward only when pouring the liquid-containing material, suppresses side leakage of the liquid-containing material, and forms a deposit layer (cake layer) with little variation. After the liquid-containing material has been placed on the sheet-shaped part-equipped body 10, it moves upward and prepares for the next skiving. At this time, a mechanism or process may be provided to scrape off or wash away any remaining material adhering to the walls within the formwork.

When the slurry is a water-containing liquid, the entrained water after straining includes water that directly passes through the sheet-like part equipment 10, water that seeps out from the side surface of the deposit layer, and water that oozes out from the side surface of the deposit layer. There are things that have accumulated and are floating. In order to remove water from the sides and top, draining is performed in the post-process. If water remains on the sides or top, a large amount will evaporate at once, forming a water vapor saturated layer at the interface between the water surface and the gas, reducing the evaporation rate, and causing a temperature drop due to the latent heat of vaporization. This is because the water evaporation efficiency deteriorates and the drying time becomes longer.

In FIG. 10, after a paste-like liquid-containing substance is supplied onto a surface-like part-equipped body 16 without holes through a spray nozzle 15, the deposit layer of the liquid-containing substance 14 is removed by leveling the liquid-containing substance 14 using a press machine 17. Shows how to form.

In FIG. 11, a paste-like liquid-containing material 19 in a measuring tank 21 on a load cell type measuring device 20 is poured out onto a planar part-equipped body 22 without holes, and the upper surface is leveled with a wiper 23 to form a deposit layer. It shows you how to do it.

Although not shown, the liquid-containing material 14 may be leveled with a wiper 23 in FIG. 10. Further, in FIG. 11, the liquid-containing material may be leveled by a press machine 17.

In the present invention, the sheet-like portion-equipped body may be used in a separated and independent state one by one, or two or more sheets may be used in a state in which a frame-like holder holds them. FIG. 12 shows an example of this, and as shown in FIGS. 12(a) and 12(b), a plurality of sheet-like portion-equipped bodies 30 are held in a frame-like holder 31. Note that (b) is a view taken along the line BB in (a).

After the liquid-containing substance is attached to the planar part-equipped body 30, the frame-shaped holder 31 is arranged in an upright position in parallel as shown in FIGS. (c) and (d). In this case, the deposit layers do not face each other. Note that (c) is a view taken along the line CC in FIG. (d).

In the present invention, as shown in FIG. 13, a plurality of frame-shaped holders 31 may be connected by a connector (hinge) 32 to form an integrated frame-shaped holder unit. This frame-shaped holder unit can be folded so that the deposit layers are alternately placed back-to-back and facing each other. Note that (b) is a view taken along the line BB in (a).

[Liquid drainer (drainer)]
The sheet-like part-equipped body to which the liquid-containing material has been attached may be immediately dried, but the sheet-like part-equipped body may be placed in an upright state (upright state) and the liquid may be drained.

When the liquid-containing material is sludge, etc., when the liquid-containing material is attached to the sheet-shaped part-equipped body, the liquid will come out on the surface of the deposit layer, so by keeping the sheet-shaped part-equipped body in an upright position. It is preferable to let the floating liquid fall by gravity and drain the liquid (in the case of water-containing material, drain it).

When the planar portion-equipped body is placed in an upright state, the planar portion of the planar-shaped portion-equipped body may be vertical, or may be tilted within a range of ±45° from the vertical.

When the sheet-like part-equipped body is in an upright state (upright state), and when the sheet-like part-equipped body has a slit-like part extending in one direction like a cage-like body, the slit-like part is It may be oriented in the vertical direction, it may be oriented in the horizontal direction, or it may be oriented in a direction between the two directions. Note that if the slit-shaped portion is oriented substantially in the vertical direction, the liquid draining properties will be improved, but the liquid-containing material will tend to slip off. When the slit-shaped portion is oriented substantially horizontally, the liquid-containing material is prevented from slipping down, but the liquid drainage properties are inferior to those when the slit-like portion is oriented vertically.

<Another mode of draining liquid>
Draining may be performed by gravity filtration, by using centrifugal force, or by squeezing. Furthermore, two or more of the above methods of draining using gravity, draining using centrifugal force, and draining squeezed liquid may be combined.

An example of the draining method is shown in FIGS. 14 to 23.

FIG. 14 shows an example of draining using the gravity filtration method, in which the planar portion-equipped body 40 is set approximately horizontally, and the slurry-like deposits 39 on the planar-shaped portion-equipped body 40 are drained.

In the case of this method, the planar portion-equipped body 40 may be made obliquely as shown in FIG. 15. If it is placed diagonally, drops (water droplets, etc.) will fall more easily than if it is placed horizontally.

In FIG. 15, the deposit 39 is placed on the upper side of the sheet-like portion-equipped body 40, but it may be placed on the lower side as shown in FIG. 16. According to FIG. 16, compared to FIG. 15, the amount of liquid in the adhered material near the sheet-like part-equipped body 40 is smaller, making it easier to dry.

17 to 20 show a method for draining pasty deposits using a centrifugal method. Reference numeral 44 indicates a rotation axis. In FIGS. 19 and 20, reference numeral 45 indicates a rotating arm, and 46 indicates a rotating bucket.

In FIGS. 17 to 19, rotation may be in either direction. Rotation in both directions is more preferred. In FIGS. 17 to 19, the rotation speed is such that the deposit 39 does not peel off. According to the system shown in FIG. 20, the rotational speed can be increased compared to those shown in FIGS. 17 to 19, but there is a drawback that liquid content gathers in the vicinity of the planar part-equipped body within the deposit 39.

FIG. 21 shows a form in which the deposits 39 are pressed and liquid removed using a press 50. While the sheet-shaped part-equipped body 40 is standing still, the press machine 50 moves up and down to apply squeezing force, and the liquid content oozes out from the deposits 39. In FIG. 22, the roller 51 is used for squeezing. FIG. 22(a) shows a configuration in which the roller 51 is fixed in position and the sheet-like portion-equipped body 40 is moved to be compressed. FIG. 22(b) shows a configuration in which the sheet-shaped portion-equipped body 40 is left still and the roller 51 is moved to compress it. The effect of liquid removal is the same, and it does not matter which form is adopted.

In FIG. 23, the sheet-shaped part-equipped body 40 and the deposit 39 thereon are squeezed by sandwiching pressing plates 55 and 56 made of perforated plates or the like from above and below. 57 indicates a roller.

In addition, if it is squeezed too strongly, deposits may get into the gaps between the nets and the like of the sheet-shaped part-equipped body, resulting in poor drying or failure to peel off after drying. Unlike a dehydrator, it does not use force to squeeze out the interstitial water between particles or the adhering water attached to the particles, but instead only removes the liquid that seeps out (such as free water). Since this is the purpose, it is desirable to appropriately control the pressurizing force.

The above process of attaching a liquid-containing material to the planar part of the planar part-equipped body and the subsequent liquid draining process may be provided in the same space as the next drying process, for example, in the drying chamber, but In order to avoid unnecessarily increasing humidity and lowering drying efficiency, it is better to configure the process so that it can be carried out in a separate space from the drying room.

Furthermore, in the liquid draining step, it is preferable to provide a mechanism that can apply heat so that the liquid-containing material attached to the planar portion can be maintained at a desired temperature. For example, when water is at a temperature lower than around 15° C., its viscosity increases rapidly and its movement speed decreases. Even if the water drops are allowed to fall vertically, the water drops will grow long and cause problems in draining. Furthermore, if the temperature of the liquid-containing material decreases, not only will energy be consumed to raise the temperature in the subsequent drying chamber, but also the drying time will become longer due to the time taken to raise the temperature.

Therefore, when the liquid-containing material adhering surface portion device is erected before entering the drying chamber, it is preferable to have a structure that allows heat to be applied. Dripping of water can be promoted by providing a cover such as a hood and placing a heat source (such as an electric heater) inside to heat the inside of the hood.

The heat source can be placed anywhere, but if it is attached to the top of the hood, water vapor may become trapped on the surface of the heat source depending on the design structure of the hood, so detailed consideration is required. If it is installed on the bottom, water droplets that fall may land on the top of the heat source, generating water vapor and creating a high-humidity environment inside the hood. Therefore, it is important to carefully consider the flow of gas inside the hood. It becomes necessary. When the heat source is installed on the side surface, it is possible to relatively efficiently raise the temperature of the liquid-containing material and the sheet-shaped part-equipped body.

It is also possible to raise the temperature by sending steam or hot air into the hood. In this case, a part of the warm air introduced into the drying chamber is guided into the hood, a part of the warm air taken in from the drying chamber is guided into the hood, or a part of the exhaust air at the outlet of the drying room or By introducing the entire amount into the hood, the atmosphere in the hood can be heated, and the temperature of the liquid-containing material adhering surface portion equipped body can be adjusted or maintained so that the temperature does not drop. Of course, it may be equipped with both power supply installation and warm air introduction.

The longer the residence time in this covered space, the better; however, it is preferable to ensure a residence time of at least 5 minutes, more preferably 10 minutes or more. The temperature is preferably designed to be 15°C or higher, preferably 25°C or higher. Note that the humidity does not matter.

[Drying of liquid-containing materials]
If necessary, after draining the liquid as described above, the sheet-shaped part-equipped body to which the liquid-containing substance has adhered is subjected to a drying process to dry the liquid-containing substance.

This drying is preferably carried out by flowing a gas such as air along the liquid-containing material attached to the planar part-equipped body.

When performing the drying step, it is preferable that the liquid-containing material adhering surface portion device be in an upright state. In this case as well, the liquid-containing substance adhering surface portion may be vertical, or may be inclined within a range of ±45° with respect to the vertical.

This angle may be constant during the drying process or may be varied. For example, it may be made oblique at first, and become approximately vertical when the liquid-containing material dries and becomes difficult to fall off from the planar portion. In addition, by tilting the surface diagonally from the vertical position during drying to create an angle of depression with respect to the gas flow, the gas flow can directly hit a location away from the periphery of the liquid-containing material adhering surface, such as the center. By doing so, you can also reduce uneven drying.

It is thought that the faster the flow rate of the drying gas along the surface of the liquid-containing material, the higher the evaporation rate, but the gas flow separates from the liquid surface-gas interface, making it difficult to eliminate the water vapor saturated layer. Sometimes. In addition, if the speed is too high, the adhered flow-containing material may fall. Therefore, the flow rate of the drying gas flowing along the surface of the liquid-containing material is preferably 0.5 m/sec or more, for example, about 0.5 to 10 m/sec. The gas flow rate may be constant or may be varied. By varying the wind speed, the way the air hits the liquid-containing material and the position at which it hits changes, so it can be expected to have the effect of reducing uneven drying.

The gas may flow in a substantially horizontal direction along the surface of the liquid-containing material, may flow upward from below, or may flow downward from above. The direction of this flow may also be constant or may be changed. Changing the wind direction can be expected to reduce uneven drying.

The evaporation rate of a liquid is determined by the saturated vapor pressure near the boundary between the liquid surface and the gas, and is not controlled solely by temperature conditions, but it is also known that the higher the temperature, the higher the vapor pressure, and the higher the latent heat of vaporization. Considering this, the higher the temperature, the better.
Since this drying method performs drying by blowing air, it is preferable to adjust the temperature of the gas in advance so that there is no temperature drop (cooling) caused by blowing air. For example, when the liquid to be evaporated is water, the temperature of the gas is preferably 37°C or higher, particularly about 40 to 70°C. Further, it is preferable to adjust the humidity to 50% or less. When the material to be treated is an organic material, if the temperature exceeds 70° C., proteins and the like may denature and retain liquid (water) or emit an unpleasant odor.
The boiling point of water at 1 atm is 100°C, but if the liquid you want to evaporate is an organic solvent (solvent), it is generally lower than the boiling point of water, such as 34.6°C for ether, 56°C for acetone, and 56°C for ethyl. The temperature of alcohol is 78.4°C, and if the temperature is adjusted to the above conditions as in the case of water, it is suitable as a gas for evaporation.

Preferably, the drying step is carried out in a drying space, for example a drying chamber. In this case, the sheet-shaped part-equipped body to which the liquid-containing material has adhered may be moved within the drying chamber.

In one aspect of the present invention, a large number of liquid-containing material adhering surface portions are arranged in an upright manner on a transfer member at predetermined intervals and are continuously moved within a drying chamber. In this case, after moving the first travel zone at the top of the drying chamber from one end of the chamber to the other end, the first travel zone is moved to the second travel zone directly below the sheet-like part-equipped body, and In the second travel zone, the planar portion-equipped body may be moved from the other end side to the one end side. Furthermore, it is possible to move the sheet-shaped part-equipped body from the one end side of the second running zone to a third running zone immediately below, and to move the planar part-equipped body from the one end side to the other end side in the third running zone. It may be moved from the third running zone to the fourth running zone immediately below, and in the fourth running zone, the sheet-like part equipped body may be moved from the one end side to the other end side.

In addition, when moving from the first running zone to the second running zone, the vertical direction of the body with the liquid-containing material adhesion surface part is reversed, and when moving from the second running zone to the third running zone, the liquid-containing material adhering When the vertical direction of the sheet-shaped part-equipped body is reversed again and transferred from the third travel zone to the fourth travel zone, the vertical direction of the sheet-like part-equipped body to which a liquid-containing substance is attached may be reversed again and again. Reversing the top and bottom direction during drying means changing the direction in which the wind blows from the perspective of the liquid-containing material, that is, the direction in which the wind flows (upwind/leeward), compared to when the wind is applied from one direction. It can also be expected to have the effect of reducing uneven drying.

When moving from the upper travel zone to the lower travel zone, air will not hit the surface of the object to be treated, so a heating means is provided to prevent the temperature of the liquid-containing material on the surface from decreasing. It is preferable. As the heating means, a method of directly applying heat such as an electric heater, or a method of indirectly applying heat such as an oil heater equipped with a heat transfer tube, a hot water heater, or a hot air heater can be used. Further, a heat insulating material or a panel that emits far infrared rays may be attached to the space.

It is preferable that the dried deposits be peeled off from the sheet-like portion-equipped body using a scraper or the like.

An example of the drying process is shown in FIGS. 24 to 27. FIGS. 24 to 27 show a state in which the sheet-like part-equipped body 30 having deposits is placed in the drying chamber 60, and hot air is ventilated into the drying chamber 60 from the air chamber 61.

In FIGS. 24 to 27, a plurality of planar parts 30 held by a frame-shaped holder 31 are arranged in one stage (FIGS. 24 and 25) or in multiple stages above and below (two stages in FIGS. 26 and 27). . In the planar portion-equipped body 30, the surface to which deposits are attached is in the vertical direction. In FIGS. 24 and 26, warm air is ventilated from the bottom to the top. In FIGS. 25 and 27, hot air is blown from the right side to the left side of the figure.

The hot air is preferably generated by a fan and heating means (such as a heat exchanger or heater), but the exhaust gas after burning the gas is introduced as is, or mixed with other gas such as outside air, and then introduced or cooled. It may be introduced after temperature adjustment. The blower fan may be placed upstream or downstream of the heating means. In the latter case, the blower fan may be placed inside the air chamber 61 as shown in FIGS. 24 and 25.

However, the ventilation direction and ventilation mechanism may be other than those described above.

FIGS. 28 and 29 show an example of the process from adhering a liquid-containing substance to the sheet-like part-equipped body to introducing it into the drying chamber and taking it out from the drying chamber.

In FIG. 28, a liquid-containing material 68 is supplied from a supply device 69 onto a planar portion-equipped body 67, and a press device 71 smoothes the upper surface of the liquid-containing material and removes the liquid. Next, the sheet-like part-equipped body 67 is stood up and moved in the drying chamber 60 in an upright state by a transfer means (not shown), and the deposits are dried by warm air from the air chamber 61. When the planar part-equipped body 67 with the deposits dried and turned into a dried material 68D comes out of the drying chamber 60, the dried material 68D is scraped off by a scraper 74, and the dried material 68D is stored in a storage box 76. The scraper 74 may move vertically or horizontally.

The planar part-equipped body 67 is collected in a collection box 77. Reference numeral 78 indicates a gas heating means, and 79 indicates a blower fan.

In FIG. 29, a liquid-containing material 68 is supplied from a supply device 69 onto a planar portion-equipped body 67, and the upper surface of the liquid-containing material is leveled and dehydrated by a press device 72. Next, the sheet-like part-equipped body 67 is stood up and moved in the drying chamber 60 in an upright state by a transfer means (not shown), and the deposits are dried by warm air from the air chamber 61. In FIG. 29, the sheet-like part-equipped body 67 moves to the upper stage side of the drying chamber 60, then moves to the lower stage side, and moves in the opposite direction on the lower stage side.

When the sheet-like part-equipped body 67 with the attached matter dried and turned into a dried material 68D comes out of the drying chamber 60, the dried material 68D is stripped off by a scraper 75, and the dried material is stored in a storage box 76. The planar portion-equipped body 67 is transferred by a circulating transfer means (not shown) and sent to a liquid-containing material adhesion process. Other symbols in FIG. 29 indicate the same parts as in FIG. 28.

As described above, the drying method and drying apparatus according to the present invention are new inventions that differ from Patent Documents 1 to 3 in the following points.

Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2000-263098) describes (1) a simple method for concentrating sludge in all fields, including sludge that is generated through biological treatment and settles naturally, and sludge that settles using a flocculant; This is a sludge treatment system and its treatment device that efficiently treats sludge using a small container and (2) an air-permeable and water-permeable sheet, and this means directs hot air that has passed through the air-permeable and water-permeable sheet into the sludge in the thickness direction. This is different from the embodiment of the present invention because the sludge is dried by passing the sludge through the sludge.

Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2009-101276) discloses a sludge drying method and a sludge drying apparatus for efficiently drying sludge caused by sunlight. 1) A sludge placing section for placing and drying sludge and a sludge supply means, (2) A blowing means for blowing air in the drying chamber, and (3) Air flowing parallel to the sludge placing surface. A sludge drying method and device configured to blow air, that is, to use a drying chamber that allows sunlight to pass through, and to carry out sludge supply and sludge placement in the drying chamber. This configuration is different from the embodiment of the present invention.

Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2016-209814) discloses a concentrating device that concentrates sludge added with a drug by gravity filtration while conveying it through a filter, and then a pair of sludge that is concentrated by the concentrating device. A dewatering device that pressurizes and dewaters the sludge while conveying it between the belts of This is a sludge dewatering and drying system that consists of a drying device that dries the sludge while being conveyed by a conveyor, and is configured to blow air in the direction of travel of the belt conveyor that runs around the belt carrying the sludge that has been fragmented by the cutting device. Therefore, this embodiment is significantly different from the embodiment of the present invention.

[Example 1]
<Purpose of the experiment>
We will confirm the effect of promoting drainage by erecting screen girders with sludge attached.

<Experimental method>
A ``screen girder'' with 18 mesh openings was stretched over a resin ``frame'' to create a ``screen girder'' with dimensions of 25 cm x 35 cm.

Digested sewage sludge that had been coagulated in advance was placed on this cage girder, and its drainage characteristics were investigated.

The sewage digested sludge used in the evaluation was collected from the second digestion tank of the anaerobic sludge digestion tank at the A treatment plant. The TS concentration immediately after collection was 1.8%.

The flocculant used was PC696, a product sold by Kurita Water Industries, Ltd., which was adjusted to a dissolved concentration of 0.2% using tap water.

100 ml of the polymer solution was added to 1000 ml of the sludge slurry, and the mixture was stirred for 30 seconds at a rotational speed of 100 rpm in a beaker. As shown in FIG. 30, this agglomerated slurry was poured onto the above-mentioned screen girder on which a 20 cm x 30 cm formwork was placed.

After 1 minute, the mold was removed, and a permeate collection funnel and graduated cylinder were placed under the screen girder. In Case-1, after removing the formwork, water was drained horizontally, and in Case-2, after removing the formwork, the water was drained vertically. Draining was carried out for a total of 60 minutes.

The amount of drained water was measured from the scale on the graduated cylinder. The results are shown in FIG. 31.

As shown in Figure 31, the amount of entrained water collected in Case-2, which is set up with screen girders, is about 15% higher, and the amount of water carried into the drying room can be reduced. If a large amount of water is brought in, the humidity in the drying chamber will increase, which will reduce drying efficiency, and the latent heat of evaporation will lower the temperature of the water and sludge layer, leading to a reduction in evaporation efficiency.

[Example 2]
<Purpose of the experiment>
The drying effect of erecting sludge-covered cages will be confirmed.

<Experimental method>
The sludge prepared under the conditions shown in Example 1 was placed on a screen girder and drained, then placed vertically in a commercially available gardening greenhouse made with a vinyl cover and heated from the sides. The drying characteristics were investigated by blowing air.

A small electric fan was used to blow air at a wind speed of 3 m/sec (flow direction and wind speed were both fixed), and drying was performed by sending air that had been adjusted to a temperature of 65° C. and a humidity of 40%.

100 ml of the polymer solution was added to 1000 ml of the sludge slurry, and the mixture was stirred for 30 seconds at a rotational speed of 100 rpm in a beaker. This agglomerated slurry was poured onto the above-mentioned screen girder on which a 20 cm x 30 cm formwork was placed in the same manner as in FIG. In Case-1, after removing the formwork, we prepared 9 sheets that were left horizontally for 59 minutes and drained, and when drying, we made it possible to hold these 9 sheets horizontally at 3 cm intervals and blow hot air. Drying was carried out by blowing air from the side parallel to the screen girder. In Case-2, after removing the formwork, we prepared 9 pieces by standing them vertically for 59 minutes and draining them, and when drying, we made it possible to hold these 9 pieces vertically at 3 cm intervals and keep them warm. Drying was carried out by blowing air from the side parallel to the screen girders. In Case-3, after removing the formwork, prepare 9 pieces by standing them vertically for 59 minutes and draining them, and when drying, return these 9 pieces to a horizontal position at 3 cm intervals so that they can be held. Drying was carried out by blowing warm air from the side parallel to the screen girders.

Every hour, a sample piece was taken from the center of the middle of the nine screen girders, and the moisture content of each piece was analyzed. The results are shown in FIG.

As shown in FIG. 32, Case-2 with erected screen girders had clearly better drying characteristics than Case-1 with horizontal structure, and the drying time until the moisture content reached 30% was about 50% shorter. In addition, Case-3, in which the sample was left upright during draining, but returned to a horizontal position during subsequent drying, was inferior to Case-2, but the drying time was much shorter than Case-1. From the above results, it was shown that draining in an upright manner greatly contributed to shortening the drying time, and that drying in an upright position also shortened the drying time. A short drying time also means that the amount of energy consumed for drying can be reduced, so that drying costs can be lowered and the size of the drying device can also be made more compact.

[Example 3]
<Purpose of the experiment>
Using paste-like sludge that does not require draining when adhering to the sludge girders, the drying characteristics of the sludge placed horizontally and vertically are compared to confirm the superiority or inferiority of the drying effect. .

<Experimental method>
The sludge used in the evaluation was the same one that was collected at the same time as that used in Examples 1 and 2, and was collected from the second digestion tank of the anaerobic sludge digestion tank at the A treatment plant. This was concentrated using a centrifuge without using a flocculant. The centrifugal separator used was H-103n model manufactured by Kokusan Co., Ltd. The centrifuge tube and bucket were selected so that 2500 G could be applied, and the rotation speed was adjusted. Centrifugation was performed for 5 minutes (the holding time at steady state, excluding acceleration/deceleration time), the supernatant separated water was discarded, and the precipitate was scraped out with a spatula. This operation was repeated to produce the required amount of thickened sludge for use in the experiment. Note that the centrifugation resulted in a volume ratio of water:solids=2:1, and the concentration of the thickened sludge was calculated to be approximately 5.4%, and the analysis value by the drying method was 5.5%. 50 g of the concentrated sludge prepared here was weighed out, dropped onto a 20 cm x 30 cm polypropylene flat plate (thickness: approximately 2 mm), hereinafter referred to as the "plate", and spread evenly with a spatula.

In Case-1, nine plates with thickened sludge on them are prepared, and during drying, these nine plates are held horizontally at intervals of 3 cm, and hot air is blown from the sides parallel to the plates to dry them. carried out. In Case-2, nine plates with thickened sludge on them are prepared, and during drying, these nine plates are held vertically at 3 cm intervals, and hot air is blown from the side parallel to the plates. Drying was performed. In Case-3, we also prepared nine plates with thickened sludge on them, and when drying, we made it possible to hold these nine plates vertically at intervals of 3 cm. Drying was carried out by blowing air vertically parallel to the plate from below to above.

A small electric fan was used to blow air at a wind speed of 3 m/sec (flow direction and wind speed were both fixed), and drying was performed by sending air that had been adjusted to a temperature of 65° C. and a humidity of 40%.

Every hour, a sample piece was taken from the center of the middle of the nine screen girders, and the moisture content of each piece was analyzed. The results are shown in FIG. 33.

As shown in FIG. 33, Case-2 in which the screen girders were erected had clearly better drying characteristics than Case-1, and the drying time until the moisture content reached 30% was about 40% shorter. Furthermore, in Case-3 where air was blown from below to above, the drying time was about 15% shorter than in Case-2 where air was blown from the side. From the above results, it was shown that drying time can be shortened by drying in an upright position. Furthermore, even when standing upright during drying, the effect of changing the air blowing direction was demonstrated, and the effect of blowing air in the vertical direction was demonstrated.

1 to 8, 10, 16, 22, 30, 40, 67 Planar part equipment 15 Spray nozzle 23 Wiper 39 Deposit 44 Rotating shaft 51 Roller 57 Roller 60 Drying chamber 74 Scraper 75 Scraper

Claims (24)

A method for drying a liquid-containing material in the form of a slurry or paste containing a liquid and particles, comprising an adhesion step of adhering the liquid-containing material to a planar part of a planar part-equipped body, and a drying step of drying thereafter. A method for drying a liquid-containing material, characterized by: 2. The method for drying a liquid-containing material according to claim 1, wherein the planar portion has a slit-like gap. 2. The method for drying a liquid-containing material according to claim 1, wherein the planar portion has a mesh shape. 2. The method for drying a liquid-containing material according to claim 1, wherein the planar portion has irregularities. 2. The method for drying a liquid-containing material according to claim 1, further comprising, after the adhering step, a liquid-draining step of removing the liquid-containing material adhering to the planar portion. 6. The method for drying a liquid-containing material according to claim 5, wherein the liquid-draining step is carried out by placing the liquid-containing material adhering surface portion device in an upright state. 7. The method of drying a liquid-containing material according to claim 6, wherein in the liquid draining step, heat is applied so that the liquid-containing material adhering to the planar portion can be maintained at a desired temperature. 2. The method for drying a liquid-containing material according to claim 1, wherein in the drying step, drying is carried out by flowing room temperature or heated gas along the surface of the liquid-containing material adhering to the planar portion. The method for drying a liquid-containing material according to claim 8, wherein in the drying step, the flow rate and/or direction of the gas is changed. 10. The method for drying a liquid-containing material according to claim 9, wherein the drying step is performed with the liquid-containing material adhering surface portion device in an upright state. 11. The method for drying a liquid-containing material according to claim 10, wherein in the drying step, an upright angle of the liquid-containing material-adhering surface portion device is changed. 11. The method for drying a liquid-containing material according to claim 10, wherein in the drying step, the top-bottom direction of the liquid-containing material-attached surface portion device is reversed. An apparatus for drying a liquid-containing material in the form of a slurry or paste containing a liquid and particles, comprising an adhering means for adhering the liquid-containing material to a planar part of a planar part-equipped body, and a drying means for drying thereafter. A drying device for liquid-containing materials, characterized in that: 14. The apparatus for drying a liquid-containing material according to claim 13, wherein the planar portion has a slit-like gap. 14. The drying device for liquid-containing materials according to claim 13, wherein the planar portion has a mesh shape. 14. The apparatus for drying a liquid-containing material according to claim 13, wherein the planar portion has irregularities. 14. The drying device for a liquid-containing material according to claim 13, further comprising a liquid draining means for draining the liquid-containing material adhering to the planar portion. 18. The apparatus for drying a liquid-containing material according to claim 17, further comprising an upright means for setting the liquid-containing material adhering surface portion device in an upright state. 19. The apparatus for drying a liquid-containing material according to claim 18, further comprising means for applying heat so as to maintain the liquid-containing material attached to the planar portion at a desired temperature. 14. The apparatus for drying a liquid-containing material according to claim 13, wherein the drying means is a means for drying the liquid-containing material by flowing room temperature or heated gas along the surface of the liquid-containing material attached to the planar portion. 21. The apparatus for drying a liquid-containing material according to claim 20, further comprising means for changing the flow rate and/or direction of the gas. 22. The apparatus for drying a liquid-containing material according to claim 21, further comprising an upright means for setting the liquid-containing material adhering surface portion device in an upright state. 23. The apparatus for drying a liquid-containing material according to claim 22, further comprising means for changing the upright angle of the liquid-containing material adhering surface portion device. 23. The apparatus for drying a liquid-containing substance according to claim 22, further comprising means for reversing the vertical direction of the liquid-containing substance-adhering surface portion-equipped body.

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