JP3574374B2 - Continuous dryer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a continuous dryer for removing liquid components such as solvents after polymerization of a synthetic resin or the like, recovering liquid components such as solvents from treatment waste liquid, and removing water from various inorganic substances. About.
[0002]
[Prior art]
In the case where the synthetic resin is polymerized in an organic solvent, for example, it is necessary to perform a drying process for removing a liquid component such as a solvent in a subsequent processing step. Further, it is necessary to perform a drying treatment in order to recover a liquid component such as a solvent from the treatment waste liquid. Further, a drying treatment may be required to remove water from chemical raw materials and various inorganic substances.
[0003]
As shown in FIGS. 4 and 5, a pair of agitating devices are provided in a horizontal trough 3 having an inlet 1 for an object to be processed at one end and an outlet 2 at the other end, as shown in FIGS. A continuous dryer in which the blades 31 are horizontally arranged is known. The stirring blade 31 includes a hollow rotating shaft 4 and stirring members such as a forward screw 5 and a backward screw 6 provided on the outer surface thereof. A jacket 8 is formed between the trough 3 and the casing 7 outside the trough 3.
[0004]
Then, when the object to be processed is indirectly heated by flowing a heat medium through the hollow rotary shaft 4 and the jacket portion 8, the liquid component contained in the object to be processed is transferred when the inside of the trough 3 is transferred by the stirring blade 31. It is dried by evaporation.
[0005]
In such a continuous dryer, the upper part of the trough 3 is opened in order to easily remove the liquid component in the object to be processed, and the opening is surrounded by a side wall 9 and an end wall 10. A steam chamber 12 is formed by attaching a ceiling plate 11 to the steam chamber 12. Exhaust ports 13 are provided at appropriate intervals in the longitudinal direction of the ceiling plate 11, and each exhaust port 13 is connected to a decompression device such as a vacuum pump (not shown).
[0006]
[Problems to be solved by the invention]
However, since an object to be processed immediately after being charged from the charging port contains a large amount of liquid components, the liquid components are easily evaporated at once, and a large amount of vapor is easily generated. For this reason, depending on the properties of the object to be treated, a large amount of bubbles may be generated in a place where steam is likely to be generated, that is, in an evaporation active area, and may overflow into the steam chamber 12 above the stirring blade 31.
[0007]
The object to be processed is lifted by the foam, and as shown in FIG. 6A, the object to be processed adheres to the side wall 9 of the steam chamber 12, and the adhered substance 14 covers the upper part of the stirring member such as the screw 5. To grow. Further, when the liquid component evaporates at a stretch, the fluidity of the object to be treated deteriorates, and the object to be treated is not bitten by the screw 5 but may be lifted on the screw 5 in the same manner as described above. Then, they have an adverse effect such as blocking the exhaust port 13 and deteriorating due to thermal deterioration due to the influence of the indirect heating as time elapses, becoming foreign matter and being mixed into the dried product.
[0008]
Further, as schematically shown in FIG. 6B, a phenomenon that the solute component 15 in the object to be processed is pushed up by the vapor flow 16 and flows to the exhaust port 13 together with the vapor flow 16 easily occurs.
[0009]
Depending on the drying treatment conditions, these swelling phenomena of the object to be processed not only occur in the vapor chamber 12 near the inlet 1 but also gradually grow to reach the vapor chamber 12 having a length of half or more of the trough 3. There is.
[0010]
In order to solve such a problem, the filling height of the object to be treated in the trough 3 or the height of the steam chamber 12 is increased in accordance with the expansion state of the object to be treated, or the speed at which the steam flow rises is reduced. For this reason, various measures have been taken to increase the size and number of the exhaust ports 13.
[0011]
However, even with the above-described contrivance, the problem of solute components adhering to the side wall 9 of the steam chamber 12 remains unsolved for the highly adherent workpiece. In addition, if the size of the exhaust port 13 is increased or the number thereof is increased, maintenance of the dryer becomes difficult.
[0012]
Therefore, an object of the present invention is to prevent the workpiece from overflowing the upper part of the stirring blade to block the exhaust port, or to cause the workpiece to adhere and grow on the side wall of the steam chamber and become a foreign substance, which is mixed into the workpiece. An object of the present invention is to provide a continuous dryer capable of preventing a drying process and obtaining a sound dried product.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following configuration.
[0014]
That is, a plurality of stirring blades are disposed in a horizontal trough having an inlet for an object to be treated at one end and an outlet at the other end, and a trough above the stirring blades is formed in a steam chamber, and the steam is formed. A plurality of exhaust ports are provided at predetermined intervals in a longitudinal direction on a ceiling plate provided at an upper part of the chamber, and the agitation is performed while heating the object to be processed, and in the process of transferring the inside of the trough, In the continuous dryer in which the liquid component contained in the evaporator is evaporated and the vapor is exhausted to the outside from the exhaust port, the stirring blades extend from the input end side end of the trough to a range including all or most of the evaporation active area. And a suppression plate for covering them is provided.
[0015]
With the above configuration, in a vaporization active region where a large amount of liquid is contained in the object to be treated and the amount of evaporation is large, solute components that are pushed up by bubbles or vapor flow generated due to evaporation of the liquid component are suppressed. It is possible to prevent the bubbles from overflowing to the upper part of the stirring blade and being blocked by contact with the plate, and to prevent the solute component from flowing up to the exhaust port together with the vapor flow.
[0016]
In addition, since the steam flow generated from the evaporative active area bypasses the tip of the suppression plate and reaches the exhaust port, it is not directly discharged from the exhaust port of the ceiling plate in the evaporative active area. For this reason, the distance from the evaporation active area to the exhaust port becomes substantially longer, and the object to be processed is less likely to be scattered to the exhaust port with the steam flow.
[0017]
As a result, problems such as blockage of the exhaust port, adhesion and growth of the object to be processed on the side wall of the evaporative active area, deterioration due to thermal degradation, and entry into the object as foreign matter are eliminated.
[0018]
Furthermore, by providing the suppression plate close to the stirring blade, the bubbles are crushed in the gap between the suppression plate and the stirring blade, and only the steam flows to the tip of the suppression plate. In addition, due to the suppression plate, the processed material having reduced fluidity is also caught in the stirring blade, and the drying of the processed material is effectively continued until the liquid content in the processed material reaches a desired content. Can be reduced.
[0019]
The length of the evaporative active zone varies depending on the drying process conditions such as the content and properties of the liquid component in the workpiece, the heating temperature, and the transfer speed of the workpiece, and the content of the liquid component in the workpiece increases. Depending on the processing conditions, such as when the temperature is relatively low, the above phenomenon can be prevented by providing a suppression plate in most of the evaporation active area.
[0020]
It is desirable that the tip of the suppression plate is located at about the middle of the length of the trough. As described above, the length of the evaporative active zone varies depending on the drying processing conditions and the properties of the object to be processed, but is usually included in a range up to the middle of the trough length. If the suppression plate is provided longer than necessary, the distance that the steam flow generated from the evaporation activation area bypasses the tip of the suppression plate and reaches the exhaust port becomes too long, and the exhaust capability is reduced. This is because the steam chamber itself becomes short, which hinders the discharge of steam.
[0021]
By forming the shape of the lower surface of the suppression plate so as to follow the rotation trajectory of the tip of the stirring blade, the gap between the suppression plate and the rotation trajectory of the stirring blade becomes substantially constant. Bubbles can be more effectively crushed, and a passage for the steam flow to the tip of the suppression plate is secured.
[0022]
When the stirring blade is a screw, the rotation trajectory is the outer periphery thereof.
[0023]
A suppression plate unit is formed by the suppression plate, an end plate provided at both ends of an upper surface of the suppression plate, and an upper plate provided between upper ends of the end plate, and a passage of steam through the end plate and the upper plate. A mouth may be formed, and a required number of the suppression plate units may be abutted and attached to the lower surface of the ceiling plate.
[0024]
According to the above configuration, it is easy to attach / detach the suppression plate to / from the trough, and the length range in which the suppression plate is provided can be easily changed for each unit.
[0025]
It is possible to adopt a configuration in which a flow path for circulating a heat medium is formed inside the suppression plate. By heating the suppression plate itself with this configuration, it is possible to prevent the temperature of the object to be processed from dropping due to latent heat of vaporization. In addition, there is an effect of indirect heating of the object to be processed by the suppression plate. As a result, the drying of the object to be processed is continued more effectively.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the attached FIGS.
[0027]
As shown in FIGS. 1 and 2, the continuous dryer according to the embodiment of the present invention is a two-shaft type in which a pair of parallel stirring blades 31 are disposed inside a horizontal trough 3. Has a hollow rotating shaft 4 and a stirring member such as a forward screw 5 and a backward screw 6 provided on the outer surface thereof.
[0028]
One end of the trough 3 is provided with an inlet 1 for an object to be processed, and the other end is provided with an outlet 2 thereof. The upper part of the trough 3 is open, and the open part is surrounded by a side wall 9 and an end wall 10, and a ceiling plate 11 is attached above these walls to form a steam chamber 12. Exhaust ports 13 are arranged on the ceiling plate 11 at appropriate intervals in the longitudinal direction, and the exhaust ports 13 are connected to a vacuum pump (not shown) to reduce the pressure in the steam chamber 12. A heating medium for indirectly heating the object to be processed flows inside the jacket portion 8 and the rotating shaft 4 formed between the trough 3 and the casing 7 outside the trough 3. The stirring member may have a hollow structure to allow a heat medium to flow.
[0029]
A progressive screw 5 is attached to the rotating shaft 4 in a range from the end of the trough 3 on the side of the inlet 1 to the outlet 2. The progressive screw 5 is formed in a shape in which a part of the outer peripheral portion of the screw is cut off at a position opposed to the rotary shaft 4 in order to enhance the stirring action of the workpiece. Further, a scraper 18 attached to the outer surface of a claw having substantially the same diameter as the outer diameter of the screw 5 is provided at one end of the cutout portion 17 (FIGS. 2A and 2B).
[0030]
A reverse feed screw 6 is attached to a portion of the rotation shaft 4 between the discharge port 2 and the end of the trough 3 on the discharge port 2 side. The reverse feed screw 6 pushes the object to be processed back and makes it easier to discharge.
[0031]
A hood 19 is provided near the upper part of the reverse feed screw 6 and the forward feed screw 5 from the end of the trough 3 on the discharge port 2 side to the entrance side of the discharge port 2 in order to easily discharge the workpiece. I have.
[0032]
In the longitudinal direction from the end of the trough 3 on the side of the inlet 1, a suppression plate 20 is provided to approach the progressive screws 5 and cover them almost to the middle of the length of the trough 3. The steam chamber 12 is left over the outlet 2.
[0033]
The suppressing plate 20 is formed such that the shape of the lower surface thereof follows the rotation locus of the tip of the screw 5, that is, the outer periphery (see FIG. 2A). The suppression plate unit 23 is formed by the suppression plate 20, the end plates 21 and 21 'provided at both ends of the upper surface thereof, and the upper plate 22 provided between the upper ends of these end plates 21 and 21'. The plates 21 and 21 'are provided with steam passage ports 24a and 24b, and the upper plate 22 is provided with steam passage ports 24c. The width of the end plates 21 and 21 ′ is formed to be slightly smaller than the width of the suppression plate 20. Two of the suppression plate units 23 are attached to the lower surface of the ceiling plate 11 by bolts (not shown), and the tip of the suppression plate 20 is positioned almost in the middle of the trough 3 as described above. I have.
[0034]
Further, between the suppression plate 20 and the side wall 9, a slight gap such that the solute component 15 does not pass is maintained for facilitating the attachment and releasing the generated steam pressure.
[0035]
As described above, the length of the evaporative active zone varies depending on the content and properties of the liquid component in the object to be treated, the rotation speed of the progressive screw 5, that is, the transfer speed of the object to be treated, and the like. Under the conditions, it is included in the range from the input side end of the trough 3 to the middle of the trough 3, that is, approximately 50%. Therefore, it is appropriate to provide the suppression plate 20 up to this range. If the suppression plate is provided longer than necessary, the distance that the steam generated from the evaporating active area bypasses the front end of the suppression plate and reaches the exhaust port becomes too long, and the exhaust capacity is reduced. It becomes shorter, and it hinders sufficient removal of liquid components.
[0036]
If the suppression plate 20 is too short, the problem described in the related art occurs. Therefore, it is necessary to cover at least about 1/5 of the length of the trough 3 from the input side end of the trough 3. The length of the suppression plate 20 is desirably changed according to the state of adhesion of the object to be processed to the side wall 9, and may be １ ／ or more, の 長 or more of the length of the trough 3. In addition, the inlet 1 needs to be installed in a range where the suppression plate 20 is provided. In the illustrated example, the inlet 1 is provided below the trough 3, but it can be provided on the side or on the upper side through the suppression plate 20.
[0037]
The suppression plate 20 may have a structure integrated with the ceiling plate 11 in which end plates 21 and 21 ′ provided at both ends thereof are directly welded and fixed to the ceiling plate 11.
[0038]
The embodiment of the present invention is configured as described above, and its operation will be described below.
[0039]
The workpiece supplied from the charging port 1 is indirectly heated by the heat medium flowing through the jacket portion 8 in the trough 3 and is transferred by the progressive screw 5 while being stirred.
[0040]
In this process, the liquid component in the processing object evaporates to vapor due to the heating of the processing object and the reduced pressure in the trough 3. The object to be processed immediately after being charged contains a large amount of liquid components, and gradually evaporates as it is transferred by the stirring blade 31. Therefore, when the liquid is transferred to the middle of the trough 3, the liquid component is reduced, and the generation of steam is reduced. However, from the vicinity of the inlet 1 to the middle of the trough 3, an evaporation active region where steam is easily generated tends to be formed.
[0041]
The vapor generated in the evaporation active area passes through the gap between the progressive screw 5 and the suppression plate 20, bypasses the tip of the suppression plate 20, and passes through a passage space of the steam flow in the suppression plate unit 23 from the passage openings 24 a and 24 b. 25, and is discharged from the exhaust port 13 through the passage port 24c.
[0042]
As described above, in the evaporation active area, many bubbles are generated as the liquid component evaporates. However, these bubbles are suppressed by the suppression plate 20 and are stirred by the progressive screw 5. At this time, the foam collapses, and only the vapor is discharged from the exhaust port 13 along the above-described path. Therefore, the object to be processed is not lifted into the steam chamber together with the bubbles. Further, as the liquid component evaporates, the fluidity of the processing object deteriorates. However, since the processing object is caught by the progressive screw 5, the processing object is not lifted by the steam chamber.
Therefore, there is no fear of adhesion growth on the side wall 9 of the evaporation active area or clogging at the exhaust port 13, and it is possible to prevent foreign substances due to thermal deterioration from being mixed into the dried product.
[0043]
Further, as described above, the steam flow generated from the evaporative active area bypasses the tip of the suppression plate 20 and reaches the exhaust port 13, so that the steam flow directly from the exhaust port 13 disposed on the ceiling plate 11 in the evaporative active area. It is not emitted. As described above, the distance from the evaporating active area having a large amount of evaporation to the exhaust port is substantially long, so that the object to be processed is less likely to be scattered to the exhaust port 13 with the steam flow.
[0044]
Further, since the lower surface shape of the suppression plate 20 is formed along the outer periphery of the screw 5, the gap between them is substantially constant, the shearing action is increased, and the foam is more reliably crushed. Only flows to the tip of the suppression plate 20.
[0045]
When the object to be processed passes through the evaporation active area, the amount of generated steam is reduced, so that problems such as the above-mentioned blockage of the exhaust port 13 and the adhesion of the object to the side wall 9 are not caused. Therefore, the length of the suppression plate 20 is limited to a necessary range as described above, and the vapor chamber 12 is left, so that the liquid component in the object to be treated is reduced to a desired content. The dried product is discharged from the discharge port 2.
[0046]
Further, since the suppression plate 20 can be attached and detached in units as described above, the range in which the suppression plate 20 is provided can be easily changed.
[0047]
As another embodiment of the present invention, as shown in FIG. 3, a flow path 28 having a heat medium inlet 26 and an outlet 27 is formed inside the suppression plate 20, and the heat medium is supplied to the inlet 26 and the outlet 27. A configuration in which the pipe 29 and the discharge pipe 30 are attached and the heat medium flows through the flow path 28 as indicated by the arrow can be adopted.
[0048]
By heating the suppression plate 20 itself, a decrease in the temperature of the object to be processed due to the latent heat of vaporization can be prevented and prevented. Further, there is also a heating effect on the object to be processed by the suppression plate 20. As a result, the evaporation of the liquid component is promoted, and the drying process of the object is more effectively performed.
[0049]
Embodiment 1
Using a twin-screw continuous dryer with a screw outer diameter of 100 mm, approach the upper part of the screw 5 and move the suppression plate 20 from the end on the inlet 1 side of the trough 3 to a length range of about 50% of the trough 3. After the heating medium is circulated through the jacket portion 8 and the heating temperature is set to 200 ° C., the pressure in the evaporation chamber 12 is reduced to 50 to 100 torr by a vacuum pump connected to the exhaust port 13, and then the resin solution containing the solvent 75 wt% is treated. The material was supplied from the inlet 1 at a supply capacity of 24 kg / h, and was transferred while being stirred by the progressive screw 5 at a rotation speed of 30 to 60 rpm to perform a drying process. As a result, the problem of swelling of the object to be treated and the problem of adhesion to the side wall of the steam chamber are eliminated, and the object to be treated can be dried to a target solvent content of 1% without lowering the drying ability. Was.
[0050]
On the other hand, when the suppression plate 20 is not provided, the swelling phenomenon of the object to be processed and a large amount of adhesion to the side wall 9 of the steam chamber in the range of 30 to 40% of the trough 3 from the end on the side of the inlet 1 side. Was observed.
[0051]
In this case, the range of the length of 30 to 40% is regarded as the evaporation active area.
[0052]
Embodiment 2
Without the suppression plate 20, the pressure in the steam chamber was reduced to about 40 torr, and the supply speed from the inlet 1 was 20 kg / h under the same processing conditions as in Example 1 except that the rotation speed of the progressive screw 5 was 60 rpm. When the processing object of the processing waste liquid containing 20 wt% of the solvent is dried, the processing object swells in a range of about 60% of the length of the trough 3 from the input side end of the trough 3 in a processing time of 2 hours. And adhesion to the side wall 9 of the steam chamber 12 was observed.
[0053]
On the other hand, when the suppression plate 20 is provided within a 30% length range of the trough 3 from the input side end of the trough 3 and the same drying treatment as described above is performed, the swelling phenomenon and the adhesion The problem is gone.
[0054]
In this case, since the rotation speed of the progressive screw 5, that is, the transfer speed of the object to be processed, is higher than that in the first embodiment, the swelling phenomenon of the object to be processed and the side wall 9 of the steam chamber exceed the evaporation active region. The evaporation active area itself is considered to be within 50% of the length of the trough 3. In addition, since the content of the liquid component in the object to be treated is relatively low, it is considered that the above phenomenon could be prevented by providing the suppression plate 20 at most of the length of the evaporation active area.
[0055]
As shown in Examples 1 and 2, it was verified that the above phenomenon can be prevented by providing the suppression plate 20 within a required length range from the input side end of the trough 3 corresponding to the drying processing conditions. Was.
[0056]
【The invention's effect】
As described above, according to the present invention, as described above, the upper part of the stirring blade is approached to the required length range including all or most of the evaporating active area from the inlet end of the trough and approaching the upper part of the stirring blade. Is provided so as to cover, solute components generated by evaporation of the liquid component in the object to be processed and solute components pushed up by the vapor flow are blocked by the suppression plate, and the bubbles are ground, solute components are removed. Is caught in the stirring blade and returned into the object. Further, even if the fluidity of the object to be treated deteriorates due to evaporation of the liquid component, the object is surely caught in the stirring blade. Then, the vapor flow generated from the evaporation active region bypasses the front edge of the suppression plate and reaches the exhaust port, so that it is difficult for the processing target to be scattered to the exhaust port with the vapor flow.
[0057]
As a result, the swelling of the object to be processed, such as bubbles overflowing to the upper portion of the stirring blade and solute components flowing to the exhaust port, is prevented, the exhaust port is blocked, and the object is placed on the side wall of the evaporation active area. Problems such as adhesion growth, deterioration due to thermal deterioration, and foreign matter mixing into the object to be processed are eliminated.
[0058]
As a result, a continuous dryer in which a sound dried product can be obtained without reducing the processing capacity is realized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a continuous dryer according to an embodiment. FIG. 2 (a) is a sectional view taken along line AA in FIG. 1 (b) is a sectional view taken along line BB in FIG. FIG. 4 is a cross-sectional view taken along line AA of the suppression plate of FIG. 4. FIG. 5 is a vertical cross-sectional view of a conventional continuous dryer. FIG. 5 is a cross-sectional view taken along line AA of FIG. Cross-sectional view taken along line AA showing adhesion growth of the processed material. (B) Cross-sectional view taken along line AA showing outflow of solute components to the exhaust port.
DESCRIPTION OF SYMBOLS 1 Inlet 2 Outlet 3 Trough 4 Rotation shaft 5 Forward screw 6 Reverse screw 7 Casing 8 Jacket part 9 Side wall 10 End wall 11 Ceiling plate 12 Steam room 13 Exhaust port 14 Deposit 15 Solute component 16 Steam flow 17 Cut-out part 18 Scraper 19 Hood 20 Suppression plates 21, 21 ′ End plate 22 Upper plate 23 Suppression plate units 24 a, 24 b, 24 c Passage port 25 Passage space 26 Inlet 27 Exit 28 Flow path 29 Supply pipe 30 Discharge pipe 31 Stirrer blade

Claims (5)

A plurality of stirring blades are arranged in a horizontal trough provided with an inlet for an object to be treated at one end and an outlet at the other end, and a trough above these stirring blades is formed in a steam chamber. A plurality of exhaust ports are provided at predetermined intervals in a length direction in a ceiling plate provided at an upper portion, and the stirring is performed while heating the object to be processed. In the continuous dryer in which the liquid component to be evaporated is evaporated and the vapor is exhausted to the outside from the exhaust port, the stirring blade is approached to the range including all or most of the evaporation active area from the input end side of the trough. A continuous dryer provided with a suppression plate for covering them. 2. The continuous dryer according to claim 1, wherein the range in which the suppression plate is provided is from the input side end of the trough to the middle of the length of the trough. 3. 3. The continuous dryer according to claim 1, wherein a shape of a lower surface of the suppression plate is formed along a rotation locus of a tip of the stirring blade. 4. A suppression plate unit is formed by the suppression plate, an end plate provided at both ends of an upper surface of the suppression plate, and an upper plate provided between upper ends of the end plate, and a passage of steam through the end plate and the upper plate. The continuous dryer according to any one of claims 1 to 3, wherein a mouth is formed, and a required number of the suppression plate units are attached to the lower surface of the ceiling plate by abutting each other. The continuous dryer according to any one of claims 1 to 4, wherein a flow path for circulating a heat medium is formed inside the suppression plate.

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