JP2846307B1 - Rotary dryer - Google Patents

Abstract

The present invention provides a rotary dryer that has a simple structure, can reduce manufacturing costs and trouble occurrences, and can further reduce operating costs. SOLUTION: A cylindrical drying cylinder rotatably attached to a center axis thereof, a jacket formed so as to surround an outer periphery of the drying cylinder and supported by something other than the drying cylinder, and A sealing portion for enclosing a space formed between the outer periphery of the cylinder and the jacket portion,
A rotary dryer having a heating device, wherein the drying cylinder is heated by introducing heating steam into the space, and at least a part of the condensate generated by condensation of the heating steam is at least part of the drying cylinder. A rotary dryer, which stores a part of the condensate in the space so that the liquid can enter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary dryer for drying powders and the like, and more particularly, to a rotary dryer capable of reducing production costs and occurrence of equipment trouble.

[0002]

2. Description of the Related Art Rotary dryers have been frequently used to dry powders and the like on a commercial scale.
A rotary drier is charged with powders and granules to be dried inside a cylindrical drying cylinder, and heats the powders and granules while rotating the drying cylinder around the center axis of the drying cylinder. The powder is dried by passing a carrier gas through the inside to remove vapor evaporated from the powder. Various types of rotary dryers are known. Among them, a steam tube type multi-tube rotary dryer is widely used.

FIG. 4 is a right side view (partly showing a sectional structure) of a steam tube type multi-tube rotary dryer. While rotating the drying cylinder 101 that is slightly inclined, the upper end 10 of the ends 103 and 105 of the drying cylinder 101 (hereinafter referred to as the bottom of the cylindrical drying cylinder; the same applies hereinafter).
From 3, a powdery or granular material to be dried by the screw conveyor 107 (hereinafter referred to as “substance to be dried”) is charged into the drying cylinder 101. The loaded object to be dried is stirred by the rotation of the drying tube 101, and is heated from the surface of the heating tube 109, which is disposed inside the drying tube and through which a heating medium such as heated steam flows. And then dried. While the material to be dried is being dried, the lower end 10 of the end of the drying cylinder is gradually moved by the inclination of the drying cylinder 101.
5 and finally the lower end 105
Taken out of On the other hand, the vapor generated by evaporation from the object to be dried is usually conveyed by a carrier gas flowing countercurrently to the object to be dried, and is removed from the inside of the drying cylinder 101 together with the carrier gas. The drying cylinder 101 is supported by the supporting units 120a and 120b, and is rotated by the driving unit 130.

FIG. 5 shows a cross section taken along line AA of the steam tube type multi-tube rotary dryer shown in FIG. A large number of heating tubes 109 exist inside the drying cylinder 101. Note that, for ease of illustration, only a part of the heating tube 109 is shown, but in practice the drying tube 101
Present all around the interior. Since the drying cylinder 101 is rotating counterclockwise in the figure, the object 201 to be dried 201 is being dried.
Is unevenly distributed rightward in the drawing in the drying cylinder 101.
In FIG. 5, the support 120a can be observed in detail. That is, the drying cylinder 101 is supported by two rollers 111 and two thrust rollers 113 on the outer periphery of the drying cylinder 101 (one roller 11).
1 and the thrust roller 113 can be observed because the support cover is partially removed, but the other roller is hidden by the support cover and is indicated by a dotted line. ). In addition, the roller 111 is mainly a drying cylinder 101.
, And the thrust roller 113 mainly supports the load in the longitudinal direction of the drying cylinder 101.

FIG. 6 shows a cross section taken along line BB of the steam tube type multi-tube rotary dryer shown in FIG. A large number of heating tubes 109 exist inside the drying cylinder 101. Note that, for ease of illustration, only a part of the heating tube 109 is shown, but in practice the drying tube 101
Present all around the interior. Since the drying cylinder 101 is rotating counterclockwise in the figure, the object 201 to be dried 201 is being dried.
Is unevenly distributed rightward in the drawing in the drying cylinder 101.
In FIG. 6, the driving unit 130 can be observed in detail. That is, the drying cylinder 101 is rotated by the gear 117 driven by the driving device 115.

[0008]

The steam tube type multi-tubular rotary dryer conventionally used has been manufactured because of the necessity of taking a complicated structure in which a large number of heating tubes are arranged inside a drying cylinder. In addition to the increase in cost, there has been a problem that troubles such as leakage of heated steam into the drying cylinder often occur frequently. Furthermore,
In order to install a steam tube type multi-tube rotary dryer, a long and narrow space is required. In addition, there is a problem that driving power for rotating the drying cylinder, gears, tires and rollers are large.

Therefore, the first problem to be solved by the present invention is that the rotary dryer is the last step of the plant, and in the unlikely event that a steam leaks into the drying cylinder and drying becomes impossible, the entire reaction step is stopped. In addition, not only the production is stopped, but also the production cost during the repair period, the chemical solution loss, and the repair cost is considerable. The second problem to be solved by the present invention is that, in the conventional type, the driving section, the drying cylinder supporting section, the bearings at the seals at both ends, etc. all have large machines and require advanced manufacturing techniques, so that labor costs are high. Reliable products cannot be obtained unless a large company has large equipment depreciation costs. This means that there are limits to cost reductions, and at least labor costs alone can be halved, and that SMEs without advanced technology and equipment can be sufficiently trusted to activate SMEs.
This is to reduce costs significantly. The third problem to be solved by the present invention is that the cost of incidental equipment is reduced (for example, conveyor equipment at the product outlet, simplification of heat insulation and heat insulation are reduced almost completely, thereby reducing heat loss. Etc.) can be considered as a problem for the whole plant. The fourth problem to be solved by the present invention is to reduce the length of the site by half by using a two-drum rotary dryer, to make the layout of the entire plant compact, and to make effective use of land. . The fifth problem to be solved by the present invention is that, in the conventional type, it is necessary to increase the holding ratio in order to lengthen the drying time according to the degree of drying. Therefore, it is possible to cope with free operating conditions. A sixth problem to be solved by the present invention is that the conventional sealing portion generally uses a gland packing, a V-packing, a diaphragm seal, etc. , The heat of friction of the seal portion is added to the drying temperature, and finally, the material to be dried melts and this enters the seal portion,
There was often a problem of falling off and being mixed into the material to be dried, but it is a reality that the problem has not yet been completely solved. Therefore, it is necessary to prevent the seal portion from being melted. A seventh problem to be solved by the present invention is to save energy by making the driving power 1/10 to 1/5 of the conventional type. An eighth problem to be solved by the present invention is to make the knocker for preventing adhesion which is a cause of noise pollution unnecessary. A ninth problem to be solved by the present invention is to improve the environment by minimizing the leakage of steam into the atmosphere. Most of these problems were the problems of the conventional type. However, it is difficult to take fundamental measures for any of these problems, and at present, orders are made in the red for parts that cannot be reduced in cost.

[0010]

A rotary dryer according to the present invention is formed so as to surround a drying cylinder, and heat steam introduced into the jacket is condensed inside a jacket supported by something other than the drying cylinder. A part of the condensate generated by the drying is reduced to about 1/2 of the weight of the drying cylinder and the weight of the material to be dried.
It is characterized in that the condensate is stored in a jacket so that the degree (or the total weight) can be supported by buoyancy. By doing so, the drying cylinder receives buoyancy from the condensed liquid, and the load on the bearing that rotatably supports the drying cylinder can be reduced.
That is, the present invention provides a cylindrical drying cylinder rotatably mounted about its central axis, a jacket formed to surround the outer periphery of the drying cylinder, and supported by something other than the drying cylinder, and A rotary dryer having a seal portion for enclosing a space formed between the outer periphery of the drying cylinder and the jacket portion, wherein the drying cylinder is heated by introducing heating steam into the space. ,
Then, a part of the condensate is stored in the space such that at least a part of the drying cylinder infiltrates a part of the condensate generated by condensation of the heating steam. is there.

The rotary dryer of the present invention has a cylindrical drying cylinder. A powdery material to be dried from one end of one of two cylindrical bottom surfaces (the bottom surface when the two bottom surfaces are removed from a hollow cylinder to form a cylindrical shape) The drying object is dried while heating the drying object from the outer wall of the drying cylinder while rotating the drying cylinder. Since the object to be dried is dried while being stirred by the rotation of the drying cylinder, the object to be dried can be uniformly dried. The material to be dried that has reached the bottom surface at the other end is taken out from the inside of the drying cylinder, stored, or transported to the next step. The drying temperature, the in-cylinder holding time, the conveying speed, and the steam temperature are set so that the object to be dried is dried to a desired degree before the object to be dried is conveyed from one end of the bottom surface to the other end. Drying conditions such as the flow rate of a carrier gas having a temperature of about the same are adjusted. The term "cylindrical" as used in the present invention refers to a hollow cylinder (not limited to a geometric cylinder, but also includes a cylinder substantially including a manufacturing error and the like, which is recognized as having a substantially cylindrical shape) provided that both bottom surfaces are removed. Not including hollow polygonal pillars with both bottoms removed. The material for forming the drying cylinder can be used without any particular limitation as long as it has a high thermal conductivity and a sufficient strength. In addition to these conditions, consideration should be given to economy, ease of work, and the like. Preferably, a steel material (stainless steel, Hastelloy, etc.) is used. The size and shape of the drying cylinder may be any according to the type of the material to be dried, the amount of drying, and the like, and the determination can be performed by a known method.

The drying cylinder is mounted so as to be rotatable about its central axis. "The central axis" refers to the cylindrical central axis formed by the drying cylinder, so that the drying cylinder performs a rotary motion similar to a roller. The method of rotatably mounting may be any known method, for example, it may be supported by supporting rollers or bearings mounted on cylinders at both ends of the drying cylinder parallel to the central axis.

The material to be dried is gradually conveyed to the outlet of the drying cylinder while being dried in the drying cylinder. In the conventional method, the conveying method can be performed by slightly inclining the drying cylinder with respect to the horizontal direction. However, in the present invention, since the two cylinders are installed horizontally (to keep the height of the object to be dried constant), the object to be dried is transported by spiral ribs (fins) formed along the inner wall of the drying cylinder. The rib is formed continuously so as to protrude from the inner wall of the drying cylinder. Since the ridges (projected portions) of the ribs are spirally formed on the inner wall of the drying cylinder at predetermined intervals, the drying cylinder is formed by tracing the ridges of the ribs from one end of the drying cylinder to the other end of the drying cylinder. It moves toward the other end while rotating clockwise or counterclockwise with respect to the central axis of the cylinder. The ribs serve to transport the object to be dried in the drying cylinder by rotating the drying cylinder. That is, since the material to be dried moves to the lower portion inside the drying cylinder due to gravity, if a spiral rib is formed on the inner wall of the drying cylinder and the drying cylinder is rotated about its central axis, the interval at which the rib is formed is formed. Move in a direction parallel to the center axis of the drying cylinder by a distance corresponding to the product of the rotation speed of the drying cylinder and the rotation speed of the drying cylinder. For this reason, the transport speed of the object to be dried can be accurately controlled by the rotation speed of the drying cylinder, so that the desired drying degree can be accurately obtained by controlling the residence time of the object to be dried in the drying cylinder. The cross-sectional shape (refers to the cross-sectional shape cut by a plane perpendicular to the direction in which the rib extends) and dimensions of the rib may be any according to the type of the material to be dried, the amount of drying, and the like. This can be done by known methods. The material for forming the rib can be used without any particular limitation as long as it has sufficient strength. However, in consideration of economy and easiness of work, a steel material (stainless steel, Hastelloy, etc., is the same as a drying cylinder). Material). In addition, since the rib functions as a heat transfer fin (both sides) by forming the rib using a material having high thermal conductivity and good corrosion resistance, it is also possible to form the rib using steel. preferable. In the case where the drying cylinder and the rib are formed of steel, welding can be used as a method for joining the drying cylinder and the rib, so that a rotary dryer can be easily and reliably manufactured. Further, it is preferable to form the ribs with a material having sufficient strength, because it also has an effect of reinforcing the drying cylinder. However, it is preferable that the outer seal surface and the roller contact surface in the range from the seal to the end surface (bottom surface) are smoothly concentrically processed by a known method. If possible, a machined portion at both ends and a heated portion are separately processed. The connection is advantageous in terms of cost.

In the rotary dryer of the present invention, a jacket is formed so as to surround the outer periphery of the drying cylinder, and the jacket is supported by something other than the drying cylinder. Since the jacket is formed to surround the outer periphery of the drying cylinder, a space is formed between the outer periphery of the drying cylinder and the jacket, and heating steam is introduced into the space as described later. Usually, the jacket portion is formed concentrically with the outer periphery of the drying cylinder when viewed from an extension of the central axis of the cylinder formed by the drying cylinder. That is, the jacket portion is arranged so that the distance between the jacket portion and the outer periphery of the drying cylinder is constant. Such a jacket-type heating makes the structure extremely simple as compared with the conventional heating tube heating, and also uses a knocker (an impact by applying an impact to prevent the adhesion of the material to be dried on the inner wall of the drying cylinder). This is preferable because the noise which has been conventionally generated by the knocker can be eliminated because the device for preventing the noise is not required. That is, when the heating by the jacket method is performed, the material to be dried is heated on the inner wall of the drying cylinder at a high temperature, and active evaporation occurs. In addition, since the jacket is supported by something other than the drying cylinder, if a part of the drying cylinder infiltrates the condensed liquid stored inside the jacket, the drying cylinder receives buoyancy from the condensed liquid. The support load of the movably supported bearing is reduced. If the jacket is supported by the drying cylinder, the reaction of buoyancy received by the drying cylinder is applied to the drying cylinder via the jacket, so that the load on the drying cylinder bearing is not reduced. On the contrary, since the weight of the condensate increases, the load on the dry cylindrical bearing increases. The jacket portion may be supported by any portion other than the drying cylinder, but the total weight of the jacket portion itself and the condensate weight, the drying cylinder, the material to be dried, the driving section and the cover, the heat retention, etc. Since it is necessary to support the weight, it is desirable to be supported by columns or the like directly supported on the foundation portion, and it is the same as known that the seismic load, wind load, and the like are also taken into account as short-term loads.

The rotary dryer of the present invention has a seal portion for enclosing a space formed between the outer periphery of the drying cylinder and the jacket portion. Since the inside of the drying cylinder is heated through the outer periphery of the drying cylinder by introducing the heating steam into the space, a seal portion is required to prevent the heating steam from freely escaping from the space. The seal portion may be any one as long as the drying cylinder can freely rotate with respect to the jacket portion and has sufficient sealing performance, but is preferably, for example, a lip seal. If sealing is performed by the lip seal method, thermal expansion in the radial direction of the drying cylinder does not significantly affect the sealing performance, and a good sealing state can be always maintained. Outside the jacket (atmosphere)
It is preferable that air at a pressure slightly higher than the pressure of the heat medium inside the jacket portion is sealed in the seal portion that separates the inside of the jacket portion from the inside. By doing so, sufficient sealing performance can be obtained even when the sliding surface pressure of the seal portion is lowered to lower the sliding resistance, and the leakage of the heat medium from the inside of the jacket portion to the outside (atmosphere) of the jacket portion is prevented. can do.

In the rotary dryer according to the present invention, in order to heat and dry the object to be dried by heating the drying cylinder, heating steam is introduced into a space between the outer periphery of the drying cylinder and the jacket portion. The heat exchange is performed between the heating steam and the contents of the drying cylinder via the outer periphery of the drying cylinder while flowing the heating steam through the space. The heating steam can be used without any particular limitation as long as it is stable and has a large heat carrying capacity.For example, heating steam is generally used, but if there is no problem with odor or fire depending on the environment, heating oil steam is used. And the like can be appropriately selected and used depending on the heating temperature and the like. However, it is preferable to use heated steam in consideration of a large film heat transfer coefficient and a large specific heat, economic efficiency, and the like. If it is necessary to increase the heating temperature when using heated steam, pressurized steam may be used. However, the jacket must have a pressure-resistant structure corresponding to this. Condensed water is generated when the heated steam condenses. However, it is preferable because water has a higher density than other oils and the like, and has a large buoyancy applied to the drying cylinder.

In the rotary drier of the present invention, the height of the condensate generated by condensing the heating steam has a buoyancy of about 1/2 of the weight of the drying cylinder and the weight of the material to be dried. Part of the condensate is stored in the space (a space formed between the outer periphery of the drying cylinder and the jacket). The heating steam introduced into the space to heat the drying cylinder is condensed by applying heat to the drying cylinder to form a condensate. Usually, a certain percentage of the generated condensate is discharged to the outside of the jacket by a trap or the like attached to the lower portion of the jacket portion.However, the condensate is removed to the extent that the entire or a part of the drying cylinder infiltrates into the condensate. Store inside. By doing so, buoyancy is generated in the drying cylinder by the condensed liquid (Archimedes' principle), and the burden on the bearing for supporting the drying cylinder can be reduced. In particular, if the amount of condensed water stored is adjusted so as to obtain buoyancy equivalent to about 1/2 of the weight of the drying cylinder and its contents, the load on the roller can be significantly reduced. Here, the reason why the weight of the contents is set to about 1/2 is that the weight of the contents is balanced when there is no material to be dried in the drying cylinder (preheating before drying and discharging before stopping). The load equivalent to the weight of the material to be dried is borne by several rollers arranged on the upper side, so the upward and downward loads are the same, and buoyancy adjustment can be easily performed and fine adjustment Is unnecessary. Further, reducing the load imposed on the roller reduces the rolling frictional resistance of the roller and reduces the driving power for rotating the rotary cylinder. In addition, since the surface of the condensed liquid that is in contact with the condensed liquid has a lower heat transfer coefficient than the surface of the condensed liquid that is condensed by the heating vapor, the surface is heated by heat exchange with the condensed liquid, so that gentle heating is obtained. Therefore, if the material to be dried only contacts the inner surface of the drying cylinder part submerged in the condensate,
Since the object to be dried is subjected to gentle heating, even if the object to be dried is weak to heating, it can not only prevent deterioration due to heat, but also has a large heat capacity, and can effectively utilize the heating effect of the carrier gas. It is effective in obtaining a drying effect. In addition, since the rotary dryer of the present invention has a large part of its outer surface stationary, it is possible to easily perform the heat insulation work and to perform the work in a state almost complete.

[0018] The two rotary dryers of the present invention are arranged in parallel, the transporting direction of the objects to be dried by the two rotary dryers is opposite, and any one of the two rotary dryers is used. The object to be dried is charged into the first rotary drier, and the object to be dried dried by the first rotary drier is loaded into a second rotary drier other than the first rotary drier among the two rotary driers. May be entered. In this way, the object to be dried is conveyed to the outlet of the first rotary dryer while being dried by the first rotary dryer, but the object to be dried discharged from the outlet of the first rotary dryer is then discharged to the second rotary dryer. Is loaded into the rotary dryer inlet of the first rotary dryer, while being dried by the second rotary dryer, being transported in a direction substantially parallel to and in the opposite direction to the transport path transported by the first rotary dryer. Is finally discharged from a second rotary dryer outlet located closer to the dryer. Therefore, when it is necessary to convey the object to be dried from the rotary dryer outlet to the vicinity of the rotary dryer inlet when the object to be dried is dried by a single rotary dryer, a separate conveying means (for example, a belt conveyor or the like) ), By combining two rotary dryers in this way, the position where the material to be dried is supplied to the rotary dryer and the position where the dried material is discharged are relatively close. Therefore, no separate transport means is required or the transport distance is significantly shortened. Furthermore, by combining two rotary dryers,
The total length of the equipment can be reduced by almost half as compared with the case where the equipment is constituted by one rotary dryer, and the equipment can be made compact and the space can be effectively used. Since the length of the transported goods is reduced by half, the transportation cost can be reduced in both land transportation and sea transportation, which is effective.

The rotation directions of the two rotary driers thus arranged are set to be opposite to each other. Then, the eccentric loads generated by the objects to be dried which are eccentrically distributed in each rotary dryer cancel each other, and the eccentric loads are almost eliminated, so that the two rotary dryers can be driven with a small power, thereby saving energy. Can be achieved. When two rotary dryers are stacked such that the plane including the two rotary shafts of the two rotary dryers is perpendicular to the ground, if the rotation directions of the two rotary dryers are the same as each other, 2 Because the object to be dried is unevenly distributed in the same direction with respect to the plane in the drying cylinder of the book,
This causes load imbalance in the equipment. On the other hand, if the rotation directions of the two rotary dryers are opposite to each other, the objects to be dried are unevenly distributed in the two drying cylinders in opposite directions with respect to the plane, and the imbalance of the load is reduced. Because they cancel, there is no load imbalance in the equipment.

Preferably, a carrier gas is circulated inside the drying cylinder. The carrier gas conveys a component evaporated from the object to be dried (in the case of an object to be dried containing water, it refers to water vapor; hereinafter, referred to as “evaporation component”) to reduce the concentration of the evaporation component in the drying cylinder. As a result, the evaporation rate is increased and the drying of the material to be dried is promoted. The carrier gas may be freely determined in consideration of the properties of the material to be dried, the type and concentration of the evaporating component, the economy, and the like, but usually nitrogen or the like can be used as long as the air and environment are not affected. The flow rate of the carrier gas may be determined based on the evaporation amount of the evaporation component and the like. The carrier gas is preferably preheated and introduced into the drying cylinder in order to promote drying of the material to be dried and reduce the heat load on the jacket. In addition, from the viewpoint of drying efficiency and the obtained degree of drying, it is preferable that the carrier gas is circulated countercurrently to the object to be dried.

An automatic air discharging valve for automatically discharging air from the inside of the jacket portion to the outside of the jacket portion (in the atmosphere) may be provided at the uppermost portion of the jacket portion. By doing so, it is possible to automatically discharge the air that has accumulated inside the jacket portion, so that the air existing inside the jacket at the start of operation or the sealing portion of the lip seal is sealed with air. The sealing air leaked into the jacket portion can be automatically discharged to the outside of the jacket portion. "Automatic air discharge valve" here
Not only means that automatically detects the presence of air and automatically opens the valve to discharge air, but also includes a simple remote-controlled open / close valve.In this case, the discharge of air was completed by visual inspection or the like. It is sufficient to confirm whether or not. In particular, when heating with heating steam, if non-condensable gas such as air mixes with the heating steam, the film heat transfer coefficient will be significantly reduced. Preferably, a valve is provided.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings based on embodiments, but the present invention is not limited thereto.

FIG. 1 is a sectional view of a rotary dryer according to a first embodiment of the present invention. The drying cylinders 2a and 2b are arranged so that the rotation center axes of the drying cylinders 2a and 2b are included in one plane, and the one plane is perpendicular to the ground. FIG. 1 shows a state where the equipment is cut by the one plane in such a state. The rotary dryer shown in FIG. 1 has two drying cylinders 2a and 2b. The drying object is charged from the inlet of the drying object of the drying cylinder 2a (the left end portion of the drying cylinder 2a). Is heated and dried while being conveyed rightward in the figure, and the material to be dried is discharged from the drying material outlet of the drying cylinder 2a (the right end portion of the drying cylinder 2a). Thereafter, the material to be dried dried by the drying cylinder 2a is loaded from the inlet of the drying material of the drying cylinder 2b (the right end portion of the drying cylinder 2b), and is conveyed to the left in the drawing while being heated and dried. The drying target is discharged from the drying target outlet of the drying cylinder 2b (the left end portion of the drying cylinder 2b).

The drying cylinder 2a has a cylindrical shape, and a spiral rib 3a is formed on the inner wall of the drying cylinder 2a along the inner wall. Although the ribs 3a are shown only at both ends of the drying cylinder 2a for convenience of illustration, they are actually formed over the entire inner wall. For this reason, the material to be dried, for example, the granular material to be dried existing inside the drying cylinder 2a is conveyed rightward in the figure by rotating the drying cylinder 2a around the central axis of the cylinder. On the other hand, the rib 3a is formed of stainless steel or carbon steel forming the drying cylinder 2a, and is attached to the inner wall by welding. Rib 3
Since a is formed of stainless steel or carbon steel having high thermal conductivity, the outer periphery 2 e of the drying cylinder and the jacket portion 1 are formed.
a, and also serves as a heat transfer fin for effectively transmitting the heat given by the heated steam introduced into the space 1f formed between the drying tube 2a and the inside of the drying cylinder 2a. The drying cylinder 2b also has a cylindrical shape, and a spiral rib 3b is formed on the inner wall of the drying cylinder 2b along the inner wall. These are the same as the drying cylinder 2a and the rib 3a. And the description is omitted.

A space 1f is formed between the outer peripheral surface 2e of the drying cylinder and the jacket 1a. Heating steam as heating steam is circulated through the space 1f to heat the drying cylinder 2a from outside. The outer peripheral surface 2e of the drying cylinder 2a is heated by the heated steam in the space 1f, and the material to be dried is heated and evaporated on the inner wall (including the surface of the rib 3a) of the drying cylinder 2a. No adhesion of dry matter,
Since there is no need for a knocker for preventing adhesion, no noise is generated by the knocker. The heating steam is heated steam inlet 51
a, 51b into the space 1f, and the outer peripheral surface 2 of the drying cylinder.
e, heat exchange is performed with the inside of the drying cylinder 2a. Part of the steam that has lost heat due to heat exchange condenses into condensed water or condensate. A part of the generated condensed water is stored inside the space 1f so as to give buoyancy to the drying cylinder 2a. Condensed water other than stored in the space 1f is discharged from a nozzle formed below the jacket portion 1a. In this embodiment, since the jacket portion 1a is supported by saddles 5a and 5c other than the drying cylinder 2a independently of the drying cylinder 2a, the weight of the stored condensed water and the drying cylinder 2a are given. The saddles 5a and 5c bear the total amount of the reaction force of the buoyancy and the jacket portion 1a, and only the buoyancy is applied to the drying cylinder 2a. Therefore, the load imposed on the rollers 19a and 19b that rotatably support the drying cylinder 2a is reduced by the buoyancy, so that rollers having a small allowable supporting load can be adopted as the rollers 19a and 19b, and the drying cylinder 2a can be used. Rotational resistance can be reduced and operating costs can be reduced. The buoyancy given to the drying cylinder 2a changes according to the amount of condensed water stored in the space 1f (the depth at which the drying cylinder 2a enters the condensed water), so that the amount of condensed water can be freely adjusted. Is preferable. Normally, if the total of the weight of the drying cylinder 2a and half the weight of the material to be dried existing inside the drying cylinder 2a is balanced with the buoyancy, the load that the rollers 19a and 19b should bear is the weight of the dried substance. Is preferable because the load on the rollers 19a and 19b and the rotational resistance of the drying cylinder 2a can be extremely reduced. Further, automatic air discharge valves 13a and 13b are provided at the uppermost part of the jacket portion 1a. In the case where the object to be dried is deteriorated by heating, the object to be dried is gently heated so that the object to be dried comes into contact only with the inner surface of the drying tube portion that has infiltrated into the condensed water. Is preferred. Although a space 1g is formed on the outer wall of the drying cylinder 2b, these are the same as the drying cylinder 2a and the space 1f, and a description thereof will be omitted.

Since the sealing portions for enclosing both ends of the space 1f are formed by the lip seals 6a and 6b, the sealing performance is hardly affected by the radial expansion of the drying cylinder 2a. Also, lip seals 6a, 6b
Is filled with air at a pressure slightly higher than the inside of the space 1f, thereby preventing the heated steam from leaking from the inside of the jacket portion 1f to the outside. Of the air used for enclosing, air that has leaked into the space 1f is automatically discharged to the outside of the space 1f by the automatic air discharge valves 13a and 13b. Although both ends of the space 1g are sealed by lip seals 6c and 6d, these are lip seals 6a and 6b at both ends of the jacket 1f.
The description is omitted because it is the same as.

The inside of the drying cylinder 2a of this embodiment and the drying cylinder 2b
A carrier gas is circulated through the inside of the cell. In this embodiment, heated air is used as the carrier gas. However, when the material to be dried is easily oxidized, or when the evaporation component or the material to be dried is explosive, an inert gas such as nitrogen gas is used. It is desirable to use Further, in the present embodiment, the carrier gas is introduced from the carrier gas inlet 66 located near the outlet of the material to be dried in the drying cylinder 2b.
Through the drying material inlet of the drying cylinder 2a and the drying material inlet of the drying cylinder 2a. That is, in this embodiment, since the carrier gas is circulated in the countercurrent to the object to be dried, the obtained degree of drying is high.

The drying cylinder 2a and the drying cylinder 2b are both driven by a motor 8 with a speed reducer, but they are driven in opposite directions (for example, when viewed from the right side of the motor 8 with a speed reducer, the drying cylinder 2a). Is rotated clockwise, and the drying cylinder 2b is rotated counterclockwise.). By rotating the drying cylinder 2a and the drying cylinder 2b in directions opposite to each other, an eccentric load caused by the uneven distribution of the object to be dried caused by the rotation can be offset. In the present embodiment, these drives are performed via the shaft coupling 9, the roller chain 12, the sprocket 11, the drive shaft 14, the reverse gear 10, and the like, but may be performed by any other known method. .

FIG. 2 is a detailed view showing the manner in which the drying cylinders 2a and 2b of the rotary dryer shown in FIG. 1 are driven. FIG. 2 shows the rotary dryer viewed from the right side in FIG.
In order to make it easier to understand the driving situation of the drying cylinder 2b and the drying cylinder 2b, some parts have been removed. Drying cylinder 2a
And a drying cylinder 2b are arranged vertically, and an electric motor 8 with a speed reducer is arranged substantially at the center thereof. The motor 8 with a speed reducer is of a variable speed, and drives the sprocket 11a via the roller chain 12a to rotate the drying cylinder 2a clockwise in the drawing. on the other hand,
The motor 8 with a speed reducer rotates the drying cylinder 2b counterclockwise in the figure by driving the sprocket 11b via the reverse gear 10a, the reverse gear 10b, and the roller chain 12b. Thus, the drying cylinder 2a and the drying cylinder 2b are rotated in opposite directions. In addition, two inspection ports 67a are provided on the cover (also serving as a drive unit mounting base) 16,
A cover 67b is provided, and the inside of the cover (also serving as a drive unit mounting base) 16 can be easily inspected through the inspection ports 67a and 67b. Further, the idler 12e applies tension to the roller chain 12a and adjusts the center distance, and the idler 12f adjusts the center distance.

FIG. 3 is a sectional view showing a section XX of the rotary dryer shown in FIG. Inside the drying cylinder 2a rotating clockwise in the figure, a dried object 30a that is heated and dried while being conveyed forward in the figure by a spiral rib 3a formed along the inner circumference, Drying cylinder 2a
Due to the rotation of the drying cylinder 2a, it is unevenly distributed on the left side in the figure with respect to the center axis of the drying cylinder 2a. On the other hand, heated steam is introduced from a heated steam inlet 51a into a space 1f formed by the outer periphery 2e of the drying cylinder 2a and the jacket portion 1a, and the outer periphery 2e is formed.
A part of the heated steam is condensed into condensed water 60a by the heat exchange through. The load to be supported by the bearing for rotatably supporting the drying cylinder 2a is condensed water 6
The height (depth) of the condensed water 60a is adjusted so as to be substantially eliminated from 0a due to the buoyancy given to the drying cylinder 2a. The height of the condensed water 60a can be adjusted by electric liquid level control.
a, the buoyancy adjusting vertical movement device 32a, and the H-shaped joint attached to the buoyancy adjustment vertical movement device 32a. The buoyancy adjusting vertical movement device 32a refers to a device that detects a vertical force applied to the drying cylinder 2a and moves up and down so as to adjust the height of the condensed water 60a so as to offset the force. For example, when the drying cylinder 2a receives a downward force (a force in a direction in which the drying cylinder 2a sinks), it is necessary to increase the buoyancy, so that the liquid moves upward to raise the liquid level, and conversely, the drying cylinder 2a faces upward. (The force in the direction in which the drying cylinder 2a is lifted up), it is necessary to reduce the buoyancy and move downward to lower the liquid level. One of the lower nozzles of the H-shaped joint attached to the buoyancy adjusting vertical movement device 32a has a jacket portion 1a.
A flexible hose 31a connected below is connected, and the other of the lower nozzles is connected to a condensed water discharge line. On the other hand, one of the upper nozzles of the H-shaped joint is provided with a pressure equalizing pipe 53a communicating with the upper part of the space 1f to prevent a siphon pipe phenomenon. It is preferable to provide a level gauge on the side surface of the jacket portion 1a or to electrically display the liquid level so that the height of the condensed water inside the space 1f can be easily checked. Further, the condensed water discharged from the space 1f is desirably converted into heated steam by reheating and reused from the viewpoint of the amount of heat held by the condensed water and effective utilization of water resources. A drying cylinder 2b is disposed below the drying cylinder 2a, and the object to be dried dried by the drying cylinder 2a is charged into the drying cylinder 2b and dried (the object 30b in the drying cylinder 2b is dried). It is conveyed from the near side to the other side in the figure.) The configuration of the drying cylinder 2b and its surroundings is the same as that of the drying cylinder 2a already described, and a detailed description is omitted. As described above, drying cylinder 2
Since b rotates counterclockwise in the figure, which is the opposite direction to the drying cylinder 2a, the object 30b is unevenly distributed to the right side in the figure with respect to the center axis of the drying cylinder 2b due to the rotation of the drying cylinder 2b. doing. Therefore, in the drying cylinder 2a, the material to be dried 30a
Are eccentrically located on the left side, but in the drying cylinder 2b,
Since 0b is eccentrically located on the right side, eccentric loads can be offset each other, and the balance of the equipment can be maintained. However, since these conditions can be assumed in advance by calculated values, it is possible to set the liquid level, and by adding about 1/2 of the weight of the material to be dried to the buoyancy, the level detection device can be controlled without delicate control. Since the control device can be simplified if the roller has sufficient strength for operation, this method is preferable in terms of cost.

In the rotary dryer of the present embodiment, two rotary dryers are arranged in parallel, and the two rotary dryers carry articles to be dried in opposite directions. The object to be dried is charged into a first rotary drier (the one disposed on the upper side in this embodiment), which is one of the dryers, and the object to be dried dried by the first rotary drier is charged. Of the two rotary dryers, the second rotary dryer (the lower rotary dryer in this embodiment) other than the first rotary dryer is configured to be charged. For this reason, unlike the case where the material to be dried is dried by a single rotary drier (formed by connecting the first rotary drier and the second rotary drier linearly), a rotary drier is used. Even when it is necessary to convey the material to be dried from the outlet to the vicinity of the rotary dryer inlet, there is no need for a separate conveying means (for example, a belt conveyor). The total length can be reduced by almost half, which contributes to the downsizing of equipment and effective use of space.

Next, a method of drying the slurry-like powder containing water using the rotary dryer shown in FIGS. 1 to 3 will be described. Here, as an example,
This is for explaining a method for drying a slurry-like powder containing water, and it goes without saying that other particles such as particles containing benzene or hexane can also be dried. The description will be made with reference to FIG. 1 unless otherwise specified.

The material to be dried supplied to the rotary dryer by the material supply conveyor 23 is conveyed to a predetermined position by the screw conveyor 24. The screw conveyor 24 transports the material to be dried,
It also plays the role of sealing the carrier gas flowing in the drying cylinder. The material to be dried conveyed by the screw conveyor 24 is supplied from above to a supply chute 25 with a scraper, and is charged from the supply chute 25 into the inlet 17a of the drying cylinder 2a. The material to be dried placed in the drying cylinder 2a falls to the lower part of the drying cylinder 2a, and is dried.
It is housed inside the groove between the ribs 3a formed spirally on the inner wall. On the other hand, the drying cylinder 2a rotates clockwise about its central axis as viewed from the right side in the figure. Rib 3a
When the drying cylinder 2a rotates as such, the spiral shape of
Since what is accommodated in the groove between the ribs 3a is formed so as to be conveyed rightward in the figure, the material to be dried is gradually conveyed rightward in the figure. The object to be dried is heated by heat exchange with heated steam and condensed water existing in the space 1f while being conveyed. The heat exchange at this time is performed via the outer periphery 2e of the drying cylinder 2a, but the object to be dried can be heated effectively because the ribs 3a function as heat transfer fins. Moisture evaporates from the heated object to be dried, and the evaporated water vapor is conveyed and removed to the outside of the system by the carrier gas flowing in the drying cylinder.

The object to be heated conveyed to the right end of the drying cylinder 2a in the figure falls down inside the cover 16, and is again returned to the drying cylinder 2b.
Is housed in the groove between the ribs 3b located at the right end of. On the other hand, the drying cylinder 2b rotates counterclockwise about the central axis of the cylinder as viewed from the right side in the figure. The spiral shape of the rib 3b is such that when the drying cylinder 2b rotates as such,
Since what is stored in the inside of the groove between b is formed to be conveyed to the left in the figure, the dried object is gradually conveyed to the left in the figure. The material to be dried is transported in space 1g
It is heated by heat exchange with heated steam and condensed water present inside. The heat exchange at this time is performed on the outer wall 2 of the drying cylinder 2b.
Although the heating is performed through f, the object to be dried can be effectively heated because the ribs 3b serve as heat transfer fins. Moisture evaporates from the heated object to be dried, and the evaporated water vapor is conveyed and removed to the outside of the system by the carrier gas flowing in the drying cylinder.

The object to be heated conveyed to the left end of the drying cylinder 2b in the figure is lifted by the product raising plate 22, and is conveyed by the screw conveyor 27 and the product conveyor 28. The screw conveyor 27 also functions as a gas seal similarly to the screw conveyor 24.

It is needless to say that the present invention is not limited to the above-described embodiment, and further includes a range substantially equivalent to the scope of the claims.

[0037]

Since the present invention is configured as described above, it has the following effects. That is, the rotary dryer has a simple structure and can reduce the manufacturing cost and the occurrence of trouble. Further, it can be installed on a compact site, and can be a rotary dryer having a small rotational driving power for the drying cylinder. Further, the heat retaining portion has a small number of rotating portions, so that the heat retaining is easy and the heat radiation area can be greatly reduced, so that the heat loss can be reduced. Since there is no knocker, noise can be significantly reduced. If the cost of peripheral facilities is included, further cost reduction can be achieved. A sufficient passage space can be secured so that the inside of the cylinder can be inspected or repaired through the door type inspection port.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotary dryer according to one embodiment of the present invention.

FIG. 2 is a drying cylinder 2 of the rotary dryer shown in FIG.
FIG. 3 is a detailed view showing a state in which a and a drying cylinder 2b are driven.

FIG. 3 is a cross-sectional view showing a cross section XX of the rotary dryer shown in FIG.

FIG. 4 is a right side view of a conventional steam tube type multi-tube rotary dryer.

FIG. 5 is a cross-sectional view showing an AA cross section of the conventional steam tube type multi-tube rotary dryer shown in FIG.

FIG. 6 is a cross-sectional view showing a cross section taken along line BB of the conventional steam tube type multi-tube rotary dryer shown in FIG.

[Explanation of symbols]

1a, 1b Jacket 1f, 1g Space 2a, 2b Drying cylinder 2e, 2f Outer peripheral surface of drying cylinder 3a, 3b Spiral rib (heat transfer fin) 5a, 5b, 5c, 5d Saddle 6a, 6b, 6c, 6d Lip Seal 7a, 7b Dust seal 8 Electric motor with reduction gear 9 Shaft coupling 10, 10a, 10b Reverse gear 11, 11a, 11b Sprocket 12, 12a, 12b Roller chain 12e, 12f Idler 13a, 13b, 13c, 13d Automatic air discharge valve 14 Driving shaft 15 Bearing and seal 16 Cover / drive unit mounting base 17a Drying material inlet 19a, 19b, 19c, 19d of drying cylinder 2a Roller 20 Thrust roller 22 Product scraping plate 23 Drying material supply conveyor 24, 27 Screw conveyor 25 Supply chute with scraper 28 Product Conveyor 30a, 30b Dry Material 31a, 31b Flexible Hose 32a, 32b Buoyancy Adjusting Vertical Movement Device 51a, 51b Heated Steam Inlet 53a Equalizing Tube 60a Condensed Water 66 Carrier Gas Inlet 67a, 67b Inspection Port (with Door) 101 Drying Tubes 103, 105 Ends of the drying tube 101 107 Screw conveyor 109 Heating tube 111 Roller 113 Thrust roller 115 Drive 117 Gears 120a, 120b Support 130 Drive unit 201 Dried material

Claims (10)

(57) [Claims] A cylindrical drying cylinder rotatably mounted on the center axis thereof; a jacket formed to surround an outer periphery of the drying cylinder and supported by a member other than the drying cylinder; A rotary dryer having a sealing portion for enclosing a space formed between the outer periphery of the drying cylinder and the jacket portion, wherein the drying cylinder is heated by introducing heating steam into the space; A rotary drier for storing a part of the condensate in the space so that at least a part of the drying cylinder infiltrates a part of the condensate generated by condensation of the heating steam. 2. The rotary dryer according to claim 1, wherein the heating steam is heated steam. 3. The rotary dryer according to claim 1, wherein a spiral rib is formed along an inner wall of the drying cylinder. 4. A rotary dryer according to claim 1, wherein two of the rotary dryers are arranged substantially parallel to each other, and a transport direction of an object to be dried by the two rotary dryers is opposite to each other. The object to be dried is charged into a first rotary dryer that is one of the two rotary dryers, and the object to be dried dried by the first rotary dryer is removed from the two rotary dryers. A rotary dryer that is charged into a second rotary dryer other than the first rotary dryer. 5. The rotary dryer according to claim 4, wherein the rotation directions of the two rotary dryers are opposite to each other.
The rotary dryer according to item 1. 6. The rotary dryer according to claim 1, wherein a carrier gas is circulated inside the drying cylinder. 7. The rotary dryer according to claim 1, wherein said seal portion is formed by a lip seal. 8. The rotary dryer according to claim 1, further comprising a plurality of rollers for supporting a fluctuating load of an object to be dried in said drying cylinder. 9. The rotary dryer according to claim 1, wherein an automatic air discharge valve is provided at an uppermost portion of said jacket portion. 10. The rotary dryer according to claim 1, wherein a thrust roller or thrust ring is provided at one end of the drying cylinder for positioning the jacket and the drying cylinder in a longitudinal direction.