JP2016093798A - Drum dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum dryer that comprises a drum having a relatively low coefficient of thermal expansion, exerting a great treatment capacity on a liquid to be dried, and having high corrosion resistance.SOLUTION: Clad steel, in which a mating material is stuck on common steel serving as a base material, is used as a material for a circular cross-section drum 2 of a drum dryer, and the mating material is arranged on the side of a surface 2b of the drum 2. At least one of stainless steel and a nickel base alloy is used as the mating material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drum dryer for evaporating and drying a liquid to be dried. In particular, as a liquid to be dried, a liquid having strong corrosive properties such as a salt represented by a chloride, an inorganic acid or an organic acid is evaporated to dryness. It is related with the drum dryer suitable for.

  For example, as a technique for treating drainage rich in chloride discharged from the final disposal site as leachate drainage, after preconcentrating the wastewater with a reverse osmosis membrane device or electrodialysis device, the vacuum concentration device is used to reach the saturation concentration of the salt. A technique for solidifying a concentrated salt aqueous solution by evaporating and drying the concentrated concentrated salt aqueous solution (concentrated salt water) with a drum dryer is known.

  Drum dryers used in the above technologies are classified into normal pressure type and vacuum type depending on the operating pressure during operation, and are classified into twin drum type, double drum type, and single drum type according to the number of drums and their rotation direction. The Furthermore, it is classified into a dip type, a spray type, a splash type, an upper roll type (single stage, multistage), a side roll type, a lower roll type, etc., depending on the liquid supply method to the drum surface.

  Each of these drum dryers is provided with a drum having a circular cross section, a scraper, etc., and a liquid to be dried (eg, a salt solution) is brought into contact with the surface of a rotating heated drum to evaporate to dryness. At the same time, it is configured to scrape off the dried product of the liquid to be dried (eg, the dried product of concentrated salt solution) from the surface of the drum with a scraper as the drum rotates (for example, Cited references 1-5).

  In the conventional drum dryer, the drum is a plating in which a nickel plating layer and a hard chrome plating layer are sequentially formed over the entire surface on one side of the plate surface of the plate-shaped plain steel (eg, SS material, SM material). Is formed of layer-coated plain steel, or is formed of hard chromium plating layer-coated stainless steel in which a hard chromium plating layer is formed over the entire surface on one side of the drum surface side in plate-like stainless steel, Or the whole drum was formed with the plate-shaped nickel base alloy.

Japanese Patent No. 4364419 Japanese Patent No. 5600489 Japanese Patent Laid-Open No. 7-8701 Japanese Patent Laid-Open No. 7-8702 JP-A-6-262001

  The above drum has the following drawbacks and problems.

  In the case of a drum made of plain steel or hard chrome plating layer coated stainless steel, the hard chrome plating layer exists on the surface side of the drum, so the surface hardness is high and the surface of the surface due to contact with the scraper is high. Although there is an advantage that scratches do not occur so much, there is a drawback that the hard chromium plating layer corrodes in a short period when the liquid to be dried is acidic. Furthermore, if the dried product of the liquid to be dried remains on the surface of the drum when the operation of the drum dryer is stopped, chloride contained in the dried product absorbs moisture as the temperature of the drum surface decreases. As a result, the hard chrome plating layer was also corroded in a short period of time. Thus, if even a slight corrosion occurs, a dimple is generated on the surface of the drum and normal operation cannot be performed, and it is necessary to perform re-plating.

  Furthermore, in the case of a drum made of stainless steel coated with a hard chrome plating layer, the thermal conductivity of stainless steel is less than about one-third that of ordinary steel, so There was a problem that the processing capacity per unit area was lowered and the moisture content of the dried product scraped by the scraper was increased. Furthermore, since the thermal expansion coefficient of stainless steel is larger than that of ordinary steel, the thermal distortion generated in the drum during operation of the drum dryer is large, and the drum dryer is, for example, a large double drum type or twin drum type. Has a problem that it is difficult to adjust the gap between the surfaces of both drums.

  In addition, in the case of a drum made entirely of a nickel base alloy, the thermal conductivity of the nickel base alloy is even smaller than that of plain steel, so the processing capacity per unit area of the drum surface for the liquid to be dried is reduced. There was a problem to do. Moreover, since the nickel-based alloy is very expensive, there is a problem that the manufacturing cost of the drum becomes high.

  The present invention has been made in view of the above-described technical background, and an object of the present invention is to provide a drum dryer having a drum having a relatively low coefficient of thermal expansion, a high processing capacity for a liquid to be dried, and a high corrosion resistance. There is to do.

  The present invention provides the following means.

[1] A rotatable drum having a circular cross section and a scraper,
The drum is to evaporate and dry by bringing the liquid to be dried into contact with the surface of the rotating heated drum.
In the drum dryer, the scraper scrapes off the dried solid matter of the liquid to be dried attached to the surface of the drum from the surface of the drum as the drum rotates.
As the material of the drum, clad steel in which a mating material is bonded to ordinary steel as a base material is used, and the mating material is arranged on the surface side of the drum,
A drum dryer in which at least one of stainless steel and a nickel-based alloy is used as the bonding material.

[2] The drum evaporates and drys an aqueous salt solution as the liquid to be dried.
2. The drum dryer according to claim 1, wherein the scraper scrapes off the dried solid solution of the salt aqueous solution as a dried solid product of the liquid to be dried.

  [3] The drum dryer according to item 1 or 2, wherein at least one of a corrosion-resistant stainless steel, a highly corrosion-resistant austenitic stainless steel, a duplex stainless steel, and a nickel-based alloy is used as the laminated material.

[4] The scraper scrapes off the dried solid of the liquid to be dried in contact with the surface of the drum.
4. The drum dryer according to any one of items 1 to 3, wherein at least a contact portion of the scraper with the drum surface is formed of a material having a hardness lower than a hardness of the surface of the drum.

[5] The scraper scrapes off the dried solid of the liquid to be dried in a proximity state that does not contact the surface of the drum.
Stellite is provided at least in the proximity of the scraper to the drum surface, or at least the proximity of the scraper is formed of hardened stainless steel having a Shore hardness of 65 HS or higher or SK material having a Shore hardness of 65 HS or higher. The drum dryer according to any one of the preceding items 1 to 3.

  [6] The drum dryer according to any one of items 1 to 5, wherein a hard chrome plating layer is formed on a surface of the laminated material.

  The present invention has the following effects.

  In the preceding item [1], as the material of the drum, clad steel obtained by bonding a mating material to ordinary steel as a base material is used, thereby suppressing a decrease in thermal conductivity and an increase in thermal expansion coefficient due to the mating material as much as possible. be able to. As a result, the processing capacity per unit area of the drum surface for the liquid to be dried can be maintained at a high level as compared with a drum formed entirely of ordinary steel, and is generated in the drum during operation of the drum dryer. Thermal strain can be kept small.

  Furthermore, the corrosion resistance of the surface of the drum can be improved by using at least one of stainless steel and a nickel-based alloy as the bonding material.

  In the above item [2], even when the liquid to be dried is a salt aqueous solution that easily corrodes the surface of the drum, corrosion of the drum surface by the salt aqueous solution can be suppressed. Thereby, salt solution can be processed satisfactorily over a long period of time.

  In the preceding item [3], the corrosion resistance of the surface of the drum can be reliably improved.

  In the above item [4], since at least the contact portion of the scraper with the surface of the drum is formed of a material having a hardness lower than the hardness of the surface of the drum, the liquid to be dried is dried while the scraper is in contact with the surface of the drum. Even in the case of scraping off a solid material, it is possible to suppress damage to the drum surface due to contact with the scraper.

  In the preceding item [5], the hardness of the scraper adjacent portion can be increased by providing the scraper at least on the portion of the scraper adjacent to the drum surface. Thereby, the useful life of a scraper can be lengthened.

  Moreover, since the scraper scrapes off the dried solids of the liquid to be dried in a close proximity without contacting the surface of the drum, even when the hardness of the adjacent portion of the scraper is increased, Since the scraper does not come into contact with the surface of the drum, it is possible to prevent the surface of the drum from being damaged by the scraper, and thereby the surface of the drum can be maintained in a good state for a long period of time.

  In the preceding item [6], the hardness of the surface of the drum can be increased by forming the hard chromium plating layer on the surface of the laminated material.

FIG. 1 is a schematic view showing the internal structure of a twin drum type drum dryer as a drum dryer according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a part of the drum, showing an example of the drum provided in the drum dryer. FIG. 3 is an enlarged cross-sectional view of a part of the drum, showing another example of the drum provided in the drum dryer. FIG. 4 is a schematic view showing an internal structure of a single drum type drum dryer as a drum dryer according to the second embodiment of the present invention.

  Next, several embodiments of the present invention will be described below with reference to the drawings.

  The drum dryer according to the first embodiment of the present invention is a twin drum type drum dryer 1 as shown in FIG.

  The twin drum type drum dryer 1 of the first embodiment is used for evaporating and drying a concentrated salt aqueous solution 40, which is a preconcentrated liquid for leachate drainage, as a liquid to be dried, and is disposed on a central axis. Two drums 2 and 2 that can rotate around the rotating shaft 3, and a scraper (for example, a scraper knife) 5 disposed on each drum 2. Both drums 2 and 2 are disposed inside a drum dryer cover including an upper cover 11 and a lower cover 12. The TDS (total soluble solid concentration) of the concentrated salt aqueous solution 40 is 10 to 30% by mass.

  Both the drums 2 and 2 have the same configuration and the same shape and the same size.

  Each drum 2 is cylindrical, and thus the cross-sectional shape of each drum 2 is formed in a circular shape. Further, circular end plates (not shown) are provided at both ends of each drum 2 in the axial direction, and both end openings in the axial direction of each drum 2 are closed by the end plates.

  Each drum 2 is dried and solidified by bringing the concentrated salt aqueous solution 40 into contact with the surface 2b formed of the outer peripheral surface of the rotating drum 2 in a heated state. The rotating shafts 3 and 3 of the drums 2 and 2 are arranged horizontally and in parallel with each other. Further, the surfaces 2b and 2b of the drums 2 and 2 are arranged close to each other, and are respectively disposed at both ends of the drum 2 between the upper sides of the adjacent portions of the surfaces 2b and 2b of the drums 2 and 2 respectively. The liquid reservoir 4 is formed by providing a board (not shown). When the drum dryer 1 is in operation, both the drums 2 and 2 have their surfaces 2b and 2b facing from the inside of the drums 2 and 2 to the outside at the liquid reservoir 4 side (that is, the upper side). Thus, it is configured to be driven to rotate in opposite directions (the rotation directions 50 and 50). Further, the peripheral speeds of the surfaces 2b and 2b of both the drums 2 and 2 are set equal to each other.

  The gap between the surfaces 2b and 2b of the drums 2 and 2 is not limited, but the gap between the surfaces 2b and 2b of the drums 2 and 2 is not damaged by contact between the surfaces 2b and 2b of the drums 2 and 2. Is particularly preferably set to 0.05 mm or more. Further, in order to suppress leakage of the concentrated salt aqueous solution 40 from the gap due to the gap being too large, the gap is particularly preferably set to 2.0 mm or less.

  Both scrapers 5, 5 have the same configuration and the same shape and size.

  Each scraper 5 removes a dry solid product (dried product of the liquid to be dried) 41 of the concentrated salt aqueous solution 40 adhering to the corresponding surface 2 b of the drum 2 from the surface 2 b of the drum 2 as the drum 2 rotates. Scraping (scraping in detail).

  In the drum dryer 1 of the first embodiment, as shown in the figure, a concentrated salt aqueous solution 40 in which leachate wastewater is concentrated to a high concentration by a concentrator (eg, vacuum concentrator) 20 is The liquid is supplied from above to the liquid reservoir 4 through the feed pipe 9. The surface of each drum 2 is heated by supplying steam from a boiler (not shown) to the inside thereof, and both the drums 2 and 2 are rotationally driven in opposite directions as described above. .

  The concentrated salt aqueous solution 40 supplied to the liquid reservoir 4 is brought into contact with the surface 2b of each drum 2 to evaporate its moisture, and then dried to the surface 2b of each drum 2. The object 41 adheres in the form of a film, and with the rotation of each drum 2, the dried object 41 is scraped (scraped) from the surface 2 b of the drum 2 by the corresponding scraper 5 and dried through the chute 13. It is dropped and accommodated in a physical container or a dry matter bag (eg, flexible container bag) 15.

  Further, the exhaust gas 43 generated by the evaporation of the concentrated salt aqueous solution 40 is sent to a scrubber (not shown) through the exhaust gas duct 10 provided at the upper end portion of the upper cover 11.

  In FIG. 1, “14” is a bottom pan, and “16” is an inspection port cover plate.

  The drum 2 is manufactured by using clad steel obtained by bonding a mating material to ordinary steel as a base material as a material of the drum 2. More specifically, the drum 2 is made from a cylindrical bent molded product of plate clad steel. It will be.

  That is, as shown in FIG. 2, the drum 2 is composed of a plate-shaped clad steel obtained by laminating a plate-shaped matching material 31 over substantially the entire surface of one surface of a plate-shaped ordinary steel as a base material 30. The material 31 is formed by being bent into a cylindrical shape so as to be disposed outside. Accordingly, the mating material 31 is disposed on the surface 2b side of the drum 2. Further, in the drum dryer 1 shown in FIG. 1, the mating material 31 is exposed on the surface of the drum 2, that is, the surface 2 b of the drum 2 is formed of the mating material 31.

  In the drum 2, both end portions in the bending direction of the plate-like clad steel bent in a cylindrical shape are joined together by welding or the like, so that the cylindrical shape is maintained. The surface 2b of the drum 2 is polished so as to have a predetermined surface property.

  In this way, as the material of the drum 2, the clad steel in which the mating material 31 is bonded to the ordinary steel as the base material 30 is used, thereby reducing the thermal conductivity and the thermal expansion coefficient by the mating material 31 as much as possible. Can be suppressed. This makes it possible to maintain a high processing capacity per unit area of the drum surface 2b with respect to the concentrated salt aqueous solution 40 (liquid to be dried) compared to a drum formed entirely of ordinary steel, and a drum dryer. The thermal distortion generated in the drum 2 during the operation of 1 can be kept small. Furthermore, the drum 2 can be manufactured at a lower cost than a drum entirely made of a nickel-based alloy.

  As the clad steel, rolled clad steel, explosive clad steel or the like is used, and the clad steel is not limited to the bonding method of the base material 30 and the laminated material 31. In the clad steel, ordinary steel as the base material 30 is not limited, and SS material (rolled steel for general structure), SM material (rolled steel for welded structure), and the like are suitably used as JIS symbols.

  The thickness of the base material 30 is not limited, and the drum 2 depends on the operating conditions such as the drum 2 temperature in the drum dryer 1, the steam pressure in the drum 2, and the peripheral speed (rotation speed) of the surface 2b of the drum 2. Are generally set to 6 to 45 mm.

  As the bonding material 31, at least one of stainless steel and a nickel-based alloy is used. Thereby, especially the corrosion resistance of the surface 2b of the drum 2 with respect to the salt aqueous solution 40 as a to-be-dried liquid can be improved.

  In particular, as the laminated material 31, a general corrosion resistant stainless steel (example: SUS316, SUS316L), a high corrosion resistance austenitic stainless steel (example: SUS836L, S31727, NAS354N), a duplex stainless steel (example: SUS329J4L, SUS329J3L) and It is desirable to use at least one of the nickel-based alloys because the corrosion resistance can be reliably improved.

  The nickel-based alloy is particularly preferably a Ni-Cr-Mo-based nickel-based alloy (eg, Hastelloy C, Incoloy 625, MA22) from the viewpoint that corrosion resistance can be improved with certainty.

  The thickness of the laminated material 31 is not limited. However, it is particularly desirable that the lower limit of the thickness of the laminated material 31 is 0.5 mm after the manufacture of the drum 2 (surface polishing of the drum 2), because the corrosion resistance can be improved reliably. In addition, it is particularly desirable that the upper limit of the thickness of the laminated material 31 is 5 mm from the viewpoint that the decrease in the thermal conductivity and the increase in the thermal expansion coefficient due to the laminated material 31 can be reliably suppressed.

  The scraper 5 is disposed in a state where the tip end portion 5a thereof is pressed against the surface 2b of the drum 2 by the air cylinder 7 with a predetermined pressing force or in a close state where it does not contact the surface 2b of the drum 2.

  In the case where the tip 5a of the scraper 5 is disposed in a proximity state where it does not contact the surface 2b of the drum 2, the gap between the tip 5a of the scraper 5 and the surface 2b of the drum 2 is 0.05 to 0.5 mm. It is desirable to set.

  In FIG. 1, “6” is a scraper holder that holds the scraper 5. Further, “8” is a scraper beam, and an air cylinder 7 is arranged on the scraper beam 8.

  When the tip 5a of the scraper 5 is arranged in a state of being pressed against the surface 2b of the drum 2, at least the tip 5a of the scraper 5 is a material whose hardness is lower than the hardness of the material forming the surface 2b of the drum 2. It is desirable to be formed by. By doing so, even if the scraped material 41 is scraped off in a state where the tip portion 5a of the scraper 5 is pressed against the surface 2b of the drum 2, the drum surface due to pressing (contact) with the scraper tip portion 5a. The damage of 2b can be suppressed. For example, when the surface 2b of the drum 2 is made of stainless steel, at least the tip 5a of the scraper 5 is made of a metal such as stainless steel having a hardness lower than that of the stainless steel.

  In the present embodiment, the hardness means the Shore hardness HS.

  On the other hand, when the tip portion 5a of the scraper 5 is disposed in a proximity state where it does not contact the surface 2b of the drum 2, the drum surface 2b is not damaged due to contact with the scraper tip portion 5a. The hardness of the material forming the tip 5a is not limited, but at least the tip 5a of the scraper 5 is formed of a material having a hardness higher than the hardness of the material forming the surface 2b of the drum 2. Particularly desirable. By doing so, the hardness of the tip 5a of the scraper 5 can be increased, and thereby the useful life of the scraper 5 can be extended.

  Specifically, it is particularly desirable to use a scraper 5 in which a stellite is locally applied to the tip portion 5a of a metal scraper 5 such as stainless steel by welding or thermal spraying. 5 can reliably increase the hardness of the tip portion 5a of the scraper 5 and can surely extend the useful life of the scraper 5. Further, the scraper 5 can be manufactured at a lower cost compared to the case where the entire scraper 5 is provided with stellite. The strength of the tip 5a can be increased.

  In addition, it is desirable that at least the tip 5a of the scraper 5 be formed of hardened stainless steel having a hardness of 65 or more or an SK material having a hardness of 65 or more in terms of extending the useful life of the scraper 5.

  Note that stellite is a high-hardness alloy mainly composed of cobalt, and more specifically, a Co—Cr—W-based cobalt-based alloy.

  Further, in the present invention, as shown in FIG. 3, the drum 2 is a hard chrome plated layer-coated clad steel in which a hard chrome plated layer 32 is formed on the surface of the laminated material 31 of the clad steel described above over substantially the entire surface. May be used as a material for the drum. In the figure, the hard chrome plating layer 32 is exposed on the surface 2 b of the drum 2, that is, the surface 2 b of the drum 2 is formed of the hard chrome plating layer 32.

  The hardness of the surface 2b of the drum 2 is increased by the hard chrome plating layer 32 in the drum made of the hard chrome plating layer coated clad steel shown in FIG. The thickness of the hard chrome plating layer 32 is not limited, but is preferably 50 to 200 μm.

  Further, according to the present invention, the material of the drum 2, the material of the scraper 5, and the arrangement structure of the scraper 5 can be appropriately selected according to the characteristics of the concentrated salt solution (liquid to be dried) 40 and the dried product 41 thereof. It is.

  Further, the present invention is not limited to the technical idea applied to the twin drum type drum dryer 1 shown in the first embodiment, but a double drum type drum dryer (not shown). Alternatively, the present invention may be applied to the single drum type drum dryer 101 shown in FIG.

  The double drum type drum dryer includes two rotatable drums having a circular cross section, and the two drums 2 and 2 in the twin drum type drum dryer 1 in which the rotation directions of both drums are shown in the first embodiment. The rotation directions 50 and 50 are opposite to each other. That is, in the double drum type drum dryer, both drums are configured to be driven to rotate in opposite directions so that the surfaces of both drums are directed from the outside to the inside of both drums on the liquid reservoir side (ie, the upper side). Yes. Furthermore, the peripheral speeds of the surfaces of both drums are set equal to each other.

  FIG. 4 shows, in particular, a splash feed type as the single drum type drum dryer 101 according to the second embodiment of the present invention. In the same figure, the code | symbol which added 100 to the component equivalent to the drum dryer 1 of the said 1st Embodiment is attached | subjected.

  In the drum dryer 101 of the second embodiment, the salt solution 140 as a liquid to be dried is supplied into the splash pan 118. Then, the salt aqueous solution 140 adheres to the surface of the rotating splash roll 117 disposed in the pan 118, and is splashed and supplied to the surface 102b of the drum 102 by the rotation of the roll 117. The technical idea of the present invention shown in the first embodiment is applied to such a single drum type drum dryer 101.

  Further, in the present invention, the liquid supply method to the drum surface in a drum dryer such as a single drum type to which the technical idea is applied is not limited to the splash feed method shown in FIG. A feed method, a lower roll transfer method, an upper roll feed method, a side roll feed method, a multi-roll feed method, or the like may be used.

  Furthermore, in the present invention, the drum dryer to which the technical idea is applied may be a normal pressure type or a vacuum type.

  Although several embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist of the present invention. .

  Next, specific examples and comparative examples of the present invention are shown below. However, the present invention is not limited to the following examples.

<Example>
A twin drum type drum dryer 1 of the first embodiment shown in FIG. 1 was prepared. The two drums 2 and 2 provided in the drum dryer 1 have the same configuration and the same shape and size. The outer diameter of each drum 2 is 40 cm and its length is 50 cm, so that the total surface area of both drums 2 and 2 is about 1.3 m ² .

  In this embodiment, the drum 2 is made of a cylindrical bent product of plate-like clad steel. In this plate-like clad steel, the base material 30 is a plain steel SS material, the laminated material 31 is a duplex stainless steel SUS329J4L, and the surface 2 b of the drum 2 is formed of the laminated material 31. In the drum 2, the thickness of the base material 30 is 16 mm, the thickness of the mating material 31 is 3 mm, and thus the thickness of the drum 2 is 19 mm.

<Comparative Example 1>
In the twin drum type drum dryer of Comparative Example 1, the drum is made of a cylindrical bent molded product of plate-shaped ordinary steel SS material, and nickel plating is applied to the entire surface of one surface on the drum surface side of ordinary steel. A layer (its thickness: 50 μm) and a hard chrome plating layer (its thickness: 100 μm) are sequentially formed, and the surface of the drum is formed of a hard chrome plating layer. The thickness of the drum is the same as the thickness of the drum 2 of the above embodiment.

  The other structure in the twin drum type drum dryer of the comparative example 1 is the same as the said Example.

<Comparative Example 2>
In the twin drum type drum dryer of Comparative Example 2, the drum is made of a cylindrical bent product of plate-like stainless steel SUS316, and one surface of the stainless steel on the drum surface side is hard chrome plated over the entire surface. A layer (thickness: 100 μm) is formed, and the surface of the drum is formed of a hard chrome plating layer. The thickness of the drum is the same as the thickness of the drum 2 of the above embodiment.

  The other structure in the twin drum type drum dryer of the comparative example 2 is the same as the said Example.

<Evaluation test>
Using the drum dryers of Example 1 and Comparative Examples 1 and 2, the same liquid to be dried was evaporated to dryness under the same operating conditions. And the moisture content of the dry solid (solid substance) of each to-be-processed liquid was investigated. The results are shown in Table 1.

The to-be-dried liquid used was a concentrated salt aqueous solution, the TDS was 20% by mass, and the main components of the dried product (solid product) were NaCl and CaCl ₂ . The supply amount of the liquid to be dried was 45 kgf / h in all cases.

  Further, in each of the drum dryers of Example 1 and Comparative Examples 1 and 2, the gap between the surfaces of both drums at the beginning of the operation was 0.3 mm. Among these drum dryers, the drum dryer of Comparative Example 2 is operated normally because the gap between the surfaces of both drums becomes large due to thermal distortion of each drum during the operation and the liquid to be dried leaks from the gap. Therefore, the operation was performed with the gaps removed from the middle of the operation (that is, the surfaces of both drums were in contact with each other).

  As shown in Table 1, the drum dryer of the example had a moisture content of 6% by mass of the dried solid, and this drying treatment capacity was substantially comparable to the drum dryer of Comparative Example 1.

  Moreover, in the drum dryer of the example, since the duplex stainless steel SUS329J4L is used as the laminated material in the clad steel which is a material for forming the drum, the corrosion resistance of the drum surface against the salt solution is the same as that of the drum dryer of Comparative Example 1. It was higher than the drum.

  The present invention is applicable to a drum dryer used for evaporating and drying a liquid to be dried such as an aqueous salt solution.

DESCRIPTION OF SYMBOLS 1, 101: Drum dryer 2, 102: Drum 2b, 102b: Drum surface 4: Liquid pool part 5, 105: Scraper 5a, 105a: Scraper front-end | tip part (contact part or contact part with drum surface of scraper)
30: Base material 31: Matching material 32: Hard chromium plating layer 40, 140: Salt aqueous solution (liquid to be dried)
41, 141: dried product of salt aqueous solution (dried product of liquid to be dried)

Claims (6)

Comprising a rotatable drum having a circular cross section and a scraper;
The drum is to evaporate and dry by bringing the liquid to be dried into contact with the surface of the rotating heated drum.
In the drum dryer, the scraper scrapes off the dried solid matter of the liquid to be dried attached to the surface of the drum from the surface of the drum as the drum rotates.
As the material of the drum, clad steel in which a mating material is bonded to ordinary steel as a base material is used, and the mating material is arranged on the surface side of the drum,
A drum dryer in which at least one of stainless steel and a nickel-based alloy is used as the bonding material. The drum is for evaporating and drying an aqueous salt solution as the liquid to be dried.
The drum dryer according to claim 1, wherein the scraper scrapes off the dried solid solution of the salt aqueous solution as a dried solid product of the liquid to be dried.   The drum dryer according to claim 1 or 2, wherein at least one of a corrosion-resistant stainless steel, a highly corrosion-resistant austenitic stainless steel, a duplex stainless steel, and a nickel-based alloy is used as the laminated material. The scraper scrapes off the dried product of the liquid to be dried in contact with the surface of the drum,
The drum dryer according to any one of claims 1 to 3, wherein at least a contact portion of the scraper with the surface of the drum is formed of a material having a hardness lower than the hardness of the surface of the drum. The scraper scrapes off the dried solid of the liquid to be dried in a proximity state that does not contact the surface of the drum,
Stellite is provided at least in the proximity of the scraper to the drum surface, or at least the proximity of the scraper is formed of hardened stainless steel having a Shore hardness of 65 HS or higher or SK material having a Shore hardness of 65 HS or higher. The drum dryer according to any one of claims 1 to 3.   The drum dryer according to any one of claims 1 to 5, wherein a hard chrome plating layer is formed on a surface of the laminated material.

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