TW201621246A - Indirect heating tube rotary dryer and drying method - Google Patents

Abstract

To improve efficiency in using a heating medium and to improve drying capacity. A condensate chamber 30 that communicates with an end opening for a group of heating pipes 11, 11, ... is formed on an end of a rotating cylinder 10. A plurality of header chambers 31, 31, ... are formed that are separated in the circumferential direction, are positioned more radially outward than the condensate chamber 30, and communicate with the condensate chamber 30. The configuration is such that the condensate chamber 30 communicates with the header chamber 31, the header chamber 31 is connected to a discharge channel 34 by a header pipe 33, and the condensate of a heating medium is guided into the discharge channel 34 by passing from the header chamber 31 to the header pipe 33.

Description

Rotary dryer with indirect heating tube and drying method

The present invention relates to a rotary dryer having an indirect heating pipe and a drying method, and more particularly to moving the object to be dried supplied to one end portion thereof to the other end portion while rotating the rotating drum about its central axis. And a rotary dryer with an indirect heating tube discharged from the other side of the rotating cylinder by supplying a heating medium to a plurality of heating tubes disposed in the rotating cylinder and contacting the moving object to be dried to the drying tube And drying methods.

A rotary dryer with an indirect heating tube, generally represented by a steam tube dryer, has a large heating area per volume unit, and thus has a high drying capacity and a high heat transfer rate.

In addition, since the heating medium and the object to be dried are not in direct contact with each other, the drying medium is not mixed in the heating medium, and the processing equipment for separating the object to be dried in the heating medium is not required, and the operation is simple, and the invention is widely used. In the chemical industry, the food industry, the iron-making industry, and the like, in particular, it has been used as a drying agent for terephthalic acid or synthetic resins, sodium carbonate, fertilizers, corn products, coal, and the like.

The dryer usually has a length of 10 to 30 m, and in the rotating cylinder, the wet powder or the granular body is brought into contact with a heating pipe heated by a heating medium through which steam or heated air flows, and the rotating cylinder The rotation is sequentially moved toward the discharge port while continuing to dry. The heating medium for heating the heating pipe is supplied to the heating pipe via a rotary joint, and heat is supplied to the wet powder through the heating pipe to dry the wet powder. The heating medium itself condenses into a condensate in the heating pipe, and flows down the gradient of the dryer relative to the heating medium, and self-rotating One end side of the barrel is discharged.

Further, a prior type dryer will be described using FIG. In the prior type dryer, the heating medium S is supplied from the piping 81 to the inside of the dryer via a rotary joint. The condensate chamber 30 is provided with a pipe 33A that penetrates the inner wall 30i and communicates with the pipe 81. The heating medium S is supplied to the condensate chamber 30 through the pipe 33A, and is supplied to the heating pipes 11, and the heating pipe 11 is heated. The heating medium S heated in the heating tube 11 becomes the condensate D, and flows down to the lower side of the condensate chamber 30. The condensate D that has flowed down is discharged from the discharge path 34 through the pipe 80 to the outside through the header pipe 33B connected to the inner wall 30i of the condensate chamber 30.

Patent Document 1 and Patent Document 2 and the like can be exemplified as the discharge form of the condensate.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3894499

[Patent Document 2] Japanese Patent Publication No. Sho 42-8110

However, in the rotary dryer having the indirect heating pipe described above, in order to discharge the dried product toward the dry matter discharge portion of the rotary cylinder, it is also important to arrange the rotary cylinder 10 downwardly, and since the condensate is often It is retained in the condensate chamber 30 which is formed at the end portion of the rotary cylinder 10 at the axial end and communicates with the end portions of the heating tubes 11, 11 ..., and the heating tubes 11 , 11 ... in the portion where the condensate stays is heated. Since the medium does not flow, the heat transfer tubes 11, 11 ... do not substantially function as heat transfer, and are a hindrance factor for improving the heat transfer efficiency of the entire heater.

Therefore, the main object of the present invention is to improve the use efficiency of the heating medium and to improve the drying ability.

The invention of claim 1 for solving the above problems is an indirect heating tube a rotary dryer comprising: a rotating cylinder; a plurality of heating tubes disposed in the rotating cylinder; a rotary driving mechanism that rotates the rotating cylinder about a central axis thereof; and a dried material supply portion that is disposed on the rotation One end side of the cylinder; and a dry matter discharge portion provided on the other end side of the rotary cylinder; and the rotary dryer with the indirect heating tube is configured such that the dried product is discharged from the supply portion to the discharge in the rotary cylinder During the movement of the portion, the dryer is indirectly heated by the heat of the heating medium flowing through the heating tube group, and is characterized in that the heating tube is connected to the end portion of the rotating cylinder in the axial direction. a condensate chamber having an open end portion of the group, a plurality of liquid collecting chambers located outside the radial direction of the condensate chamber and communicating with the condensate chamber, and being separated in the circumferential direction, and connecting the liquid collecting chamber and the setting The liquid collecting pipe of the discharge path on the center axis side is guided to the discharge path from the liquid collecting chamber.

In the present invention, a condensate chamber in which an end opening of the heating tube group is connected is formed, and a plurality of liquid collecting chambers which are separated from the condensate chamber in the radial direction and which communicate with the condensate chamber in the circumferential direction are formed. And condensing liquid of the heating medium is guided from the liquid collecting chamber to the discharge path by a liquid collecting pipe.

In other words, since the condensate flows out from the outermost side in the radial direction, the condensate does not stay in the condensate chamber, or even if it stays in a small amount, the heat can be efficiently utilized by the entire heating tube, and the heating can be improved. The use efficiency of the medium and the drying capacity per unit of the dryer.

Further, the fact that the condensate flows out from the outermost side in the radial direction means that the condensate is in a state of high energy head energy at the discharge position, so that the discharge is smooth. From this point of view, in the first rotation of the rotary cylinder, the condensate remaining in the liquid collection tube is extremely small.

The invention of claim 2 is the rotary dryer of the indirect heating tube according to claim 1, wherein the liquid collecting tube side is viewed from the outer side of the rotating cylinder end The front end side and the base end side of the discharge path side are curved toward the opposite side to the rotation direction of the rotating cylinder.

When the liquid collecting pipe is bent toward the side opposite to the rotation direction of the rotating cylinder when viewed from the outer side of the rotating cylinder end, the condensate can be smoothly guided to the discharge path through the inside of the liquid collecting pipe.

The invention of claim 3 is the rotary dryer of the indirect heating tube of the first aspect, wherein the liquid collecting tube comprises: a first portion extending outside the side of the liquid collecting chamber; and a second portion connecting the second portion The first portion and the discharge path extend in the radial direction of the rotating cylinder.

When the liquid collecting pipe is formed in the first portion extending outside the liquid collecting chamber (outside the direction of the rotating cylinder axis), the movement of the condensate from the liquid collecting chamber to the collecting pipe becomes smooth.

The invention of claim 4 is the rotary dryer of the indirect heating tube according to claim 3, wherein the first portion and the second portion are opposite to the rotation direction of the rotating cylinder when viewed from the outer side of the rotating cylinder end Side bending.

In the aspect of the third aspect, when the first portion and the second portion are viewed from the outer side of the rotating cylinder end, the condensate can be condensed toward the side opposite to the rotating direction of the rotating cylinder. The discharge path is smoothly guided through the inside of the collecting pipe.

The invention of claim 5 is the rotary dryer of the indirect heating tube according to claim 1, wherein the liquid collection chamber is partitioned by a partition wall, and the front end of the liquid collection tube communicates before the partition wall.

The condensate in the collection chamber can be smoothly moved into the collection tube.

The invention of claim 6 is the rotary dryer of the indirect heating tube according to claim 1, wherein the liquid collection chamber is partitioned by a partition wall, the partition wall being located at a supply side of the object to be dried in the axial direction of the rotary cylinder The rotation direction of the rotary cylinder is forward, and the discharge side of the object to be dried in the axial direction of the rotary cylinder is inclined rearward in the rotation direction; and the liquid collection tube includes a first portion extending outside the side of the liquid collection chamber. And the first The first portion is inclined at an angle substantially the same as the inclination angle, and the front end of the liquid collection tube communicates before the separation wall.

The effect of smoothly moving the condensate in the collecting chamber to the collecting tube is high.

The invention of claim 7 is the rotary dryer of the indirect heating tube according to claim 6, wherein the angle of inclination formed between the cross sections is 30 to 80 degrees.

The effect of smoothly moving the condensate of the liquid collection chamber into the liquid collection tube is remarkable when the inclination angle is 30 degrees to 80 degrees.

The invention of claim 8 is a drying method using a rotary dryer equipped with an indirect heating tube, which uses a rotary dryer equipped with an indirect heating tube according to any one of claims 1 to 7, to dry the dried object.

As described above, according to the present invention, the use efficiency of the heating medium can be improved, and the drying ability can be improved.

1‧‧‧Steam tube dryer

10‧‧‧Rotating cylinder

10A‧‧‧End board

11‧‧‧heat pipe

12‧‧‧Loading Department (Supply Department)

13‧‧‧Rotary joint

14‧‧‧Exporting Department

15‧‧‧Exhaust outlet

16‧‧‧ Wheels

17‧‧‧Support roller

18‧‧‧Abutment

19‧‧‧ driven gear

20‧‧‧Reducer

21‧‧‧ drive source

30‧‧‧ Condensate chamber

30i‧‧‧ inner wall (inner wall)

30o‧‧‧peripheral wall

31‧‧ ‧ collection chamber

31A‧‧‧ partition wall

31A ₀ ‧‧‧ partition wall

32‧‧‧Small hole

33‧‧‧ collecting tube

33A‧‧‧Part 1 (Pipe)

33B‧‧‧Part 2 (Collector)

34‧‧‧Drainage path

80‧‧‧Pipe (flow path)

81‧‧‧Pipe

82‧‧‧Supply Department

331‧‧‧Part 1

332‧‧‧ collecting tube

A-A‧‧‧ line

D‧‧‧ condensate

L‧‧‧ configuration line

M‧‧‧Dry

Mo‧‧‧Dry objects

R‧‧‧Rotation direction

S‧‧‧heating medium

X‧‧‧ directions

Θ‧‧‧ tilt angle

Fig. 1 is a front view of a steam tube dryer as an embodiment of the present invention.

Figure 2 is an explanatory view of the end of the rotating cylinder.

Figure 3 is a longitudinal cross-sectional view of the end of the rotating cylinder.

Figure 4 is an arrow view of line A-A of Figure 1.

Fig. 5 is an explanatory view showing another arrangement example of the heating tube group.

Fig. 6 is an explanatory view showing another embodiment.

Figure 7 is a graph of experimental results.

Fig. 8 is a schematic explanatory view of a prior example.

Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is of course not limited thereto.

1 to 4 show a steam tube dryer 1 to which the present invention is applied. Steam tube drying The machine 1 is provided with a rotating cylinder 10 having a horizontally long cylindrical shape. On both sides of the central axis x direction of the rotary cylinder 10, a tire 16 is disposed on the outer peripheral surface, and the rotary cylinder 10 is rotatably supported by the support roller 17 provided on the base 18 via the tires 16 stand by. The width between the backup rolls 17 and the lengthwise inclination angles (the inclination angles of the descending slopes of the dried objects toward the discharge portion side) are selected in accordance with the descending slope and the diameter of the rotary drum 10.

Further, in order to rotate the rotary cylinder 10, the driven gear 19 is provided around the rotary cylinder 10, and the drive gear (not shown) is engaged with the rotary gear 10, and the rotational force of the drive source 21 such as an electric motor is transmitted to the motor via the reducer 20. The gear is driven to rotate the rotating drum 10 about its axis.

The supply unit 12 of the object to be dried is connected to one side of the center axis x direction of the rotary cylinder 10 via the rotary joint 13. The supply portion 12 can be formed by various conveyor belts or chutes that pass through the rotating drum 10. The supply unit 12 from which the object to be dried is fixed is placed in the rotary cylinder 10 via the rotary joint 13 .

A plurality of heating tubes 11 are disposed in the rotating cylinder 10. The heating pipes 11 are arranged in parallel with respect to the central axis x direction of the rotating drum 10. More specifically, as shown in FIGS. 4 and 5, the heating pipe 11 is entirely arranged on the wall side (outer portion except the center portion) in the rotary cylinder 10. The number and arrangement of the heating tubes 11 can be appropriately determined.

The heating pipe 11 is supported by rotating the end plates 10A on both sides of the cylinder 10. If necessary, in order to support the heating pipe 11, a support plate (not shown) may be added to the intermediate position in the longitudinal direction of the rotary cylinder 10. The heating medium S to be described later is supplied to the heating pipe 11, for example, by heating steam.

The object to be dried placed in the rotary cylinder 10 is repeatedly raised and then dropped in the circumferential direction by the rotation of the rotary cylinder 10, and is sequentially disposed from the supply portion 12 toward the discharge portion by setting the rotary cylinder 10 to have a descending gradient. 14 was transferred. In this process, the object to be dried is heated by contact with the heating tube 11, and dried. A discharge portion 14 for drying the object is provided at an end portion of the rotary cylinder 10 opposite to the supply portion 12. The discharge portion 14 can be constituted by a chute or the like.

On the side of the discharge portion 14 in the rotary cylinder 10, there is provided for discharging steam generated by drying. An exhaust outlet 15 for a gas such as steam. The exhaust gas from the exhaust gas outlet 15 may be configured to be discharged to the atmosphere via an exhaust gas treatment device (not shown) as needed.

On the other hand, in the embodiment of the heating medium supply and discharge system, the end portion of the rotary cylinder 10 on the discharge portion 14 side is provided, and a specific configuration thereof is shown in FIGS. 2 to 4. In other words, the supply portion 82 of the heating medium S is provided at the end portion of the rotary cylinder 10 at the discharge portion 14 side, and the heating medium S is supplied to each of the heating tubes 11, 11 (the structure for supplying the branch is well known) Not shown).

The condensate D passing through the heating medium S of the heating pipe 11 is finally discharged to the outside of the dryer via the downflow path 80 by the following configuration.

That is, the condensate chamber 30 in which the end portions of the heating tubes 11, 11, ... are open is formed at the end portion of the rotary cylinder 10. Further, a plurality of (three in the illustrated example) liquid collecting chambers 31, 31, ... located outside the condensate chamber 30 in the radial direction and communicating with the condensate chamber 30 and separated in the circumferential direction are formed. The condensate chamber 30 and the sump chamber 31 are connected by a plurality of small holes 32 formed in the outer peripheral wall 300 of the condensate chamber 30 as shown in FIG. The 30i is the inner peripheral wall.

On the central side of the central axis x of the rotary cylinder 10, a discharge path 34 is provided, and the liquid collection chamber 31 and the discharge path 34 are connected by a liquid collection pipe 33, and the condensate D of the heating medium (steam) S is self-collecting liquid. The chamber 31 is guided through the collecting pipe 33 into the discharge path 34.

As shown in Fig. 2, if the liquid collecting pipe 33 is viewed from the outer side of the end of the rotating cylinder 10 (the left side viewed from the right in Fig. 3) and is bent toward the side opposite to the rotating direction of the rotating drum 10, the condensate D can be used. The discharge path 34 is smoothly guided through the inside of the liquid collection tube 33.

The liquid collecting pipe 33 preferably has a first portion 33A extending outward of the liquid collecting chamber 31, and a second portion 33B connecting the first portion 33A and the discharge path 34 and having a radius of the rotating drum 10 Extend in the direction.

The liquid collecting pipe 33 is formed to be the outer side of the liquid collecting chamber 31 (the outer side of the central axis of the rotating cylinder 10 in the x direction: the right direction of FIG. 3) as shown in FIG. 2 and FIG. In the portion 33A, the movement of the condensate from the sump 31 to the header 33 becomes smooth.

Further, as shown in FIG. 2, the first portion 33A and the second portion 33B are preferably curved toward the opposite side to the rotation direction of the rotary cylinder 10 when viewed from the outer side of the rotary cylinder 10 end. The condensate is smoothly guided into the discharge path 34 through the inside of the header pipe 33.

As shown in FIG. 2, the liquid collection chamber 31 is partitioned by a plurality of partition walls 31A, and each of the divided liquid collection chambers 31 is connected to a liquid collection tube 33. The end of each of the headers 33 can be connected to the vicinity of the partition wall 31A located rearward in the rotational direction of the two partition walls 31A of the liquid-collecting chamber 31 that is connected. As shown in FIG. 2, when the rotary cylinder 10 is rotated clockwise, the condensate remaining in the liquid collection chamber 31 moves in a direction opposite to the rotation direction of the rotary cylinder 10 (counterclockwise direction), so that it can be blocked. The flow of the movement is inclined along the partition wall 31A, so that the condensate in the liquid collection chamber 31 is smoothly moved into the liquid collection tube 33. Further, the partition wall 31A is preferably adjusted in such a manner that the liquid collecting chamber can be divided into three to six chambers.

As shown in Fig. 2, the first portion 33A of the liquid collecting pipe 33 is also preferably inclined and connected to the liquid collecting chamber 31. When the inclination angle of the first portion 33A and the liquid collection chamber 31 and the inclination angle of the partition wall 31A (the inclination angle θ formed between the cross sections of the dryer) are substantially the same angle, the flow of the condensate is smooth.

The effect of smoothly moving the condensate in the liquid collection chamber 31 into the liquid collection tube 33 is remarkable when the inclination angle θ is preferably from 30 to 80 degrees, more preferably from 45 to 75 degrees.

The dryer of the present invention can be applied to a wide range of applications represented by high density polyethylene, polycarbonate, polyester carbonate, polyphenylene ether, polyvinyl chloride, atomized iron powder, porous alumina, polycondensation. Drying of aldehyde, coal, corn germ/fiber, iron oxide, calcium carbonate, potassium fluoride, tannin, bran feed, brewer's grains, polyethylene, methyl cellulose, dried sludge, and the like.

As an arrangement of the heating pipe 11, in addition to being arranged in the radial direction as shown in Fig. 4, as shown in Fig. 5, in particular, as shown by the arrangement line L, the heating pipe 11 from the inner side toward the outer side may be provided. The arrangement of the groups is preferably such that the outer side of the heating tube is located behind the rear side with respect to the direction of rotation of the rotating drum 10. In particular, it has been found that the rotating drum 10 rotates at a high speed. When the dried product can be dropped by the self-weight along the arrangement line L, the stagnation of the dry matter does not occur between the groups of the heating tubes 11 in the rotary cylinder 10, and the contact frequency with the heating tube 11 can be increased. Therefore, the drying efficiency is improved compared with the form of FIG.

If the form shown in Figure 2, reveal once again, and by 6 illustrates another embodiment, the first, the inclination angle θ of the partition wall 31A of the partition wall 31A may be as ₀ like change. The length of the second and first portions 33A can be set to be longer than the first portion 331. Thirdly, the liquid collecting pipe 33 can be set as a curved liquid collecting pipe 332 which is gently curved as a whole.

(other)

The preferred embodiments have been described above, but the present invention can be variously modified within the scope thereof. For example, although the above example uses steam as a heating medium, other heating media may be used. Within the scope of the invention, it may be applied singly or in combination.

With respect to the dryer having substantially the same size, the example of the patent document 1 (previous example) and the example of FIG. 2 of the present invention change the peripheral speed V of the rotating cylinder, and the number of revolutions of the rotating cylinder is obtained by simulation. The amount of condensate remaining in the condensate chamber and the sump.

The simulation conditions are as follows.

Previous example (1): weekly speed V1 = 0.95 m / sec, (critical speed ratio α = 21%)

Previous example (2): weekly speed V2 = 2.0m/sec, (critical speed ratio α = 44%)

The invention has a peripheral speed V2=2.0 m/sec, (critical speed ratio α=44%)

The results are shown in Figure 7.

According to the result of FIG. 7, in the conventional example, when the peripheral speed of the rotary cylinder is increased, the amount of condensate and the amount of condensate remaining in the liquid collection chamber tend to increase as the number of rotations increases. This shows that the amount of condensate that flows into the condensate chamber per rotation is small, and the amount of condensate that can be discharged to the discharge path per rotation is small, and the difference remains in the condensate chamber and the collection chamber. On the other hand, when the peripheral speed of the rotary cylinder is lowered, it is possible to suppress an increase in the residual amount of the condensate accompanying an increase in the number of revolutions, but a certain amount of condensate remains in the condensate chamber and the collection chamber.

On the other hand, according to the collecting pipe of the present invention, even when the peripheral speed is increased, the residual amount of the condensed liquid is extremely reduced as compared with the previous example, and even if the number of rotations is increased, the residual amount of the condensed liquid does not change. This means that the entire amount of freshly taken condensate is discharged to the discharge path each time.

According to the present invention, since the discharge capacity of the condensate is extremely less than the amount of the condensed liquid flowing in, even if the peripheral speed of the rotary drum is increased, it is possible to operate the dryer at a faster peripheral speed than before. In particular, a dryer operating at a number of revolutions in which the critical speed ratio α determined by the following formulas 1 and 2 is 30 to less than 100% is suitable.

Vc=2.21D ^1/2 . . . Formula 1

α=V/Vc. 100. . . Equation 2

Here, Vc is the critical speed (m/s), the inner diameter (m) of the D-type rotating cylinder, and the critical speed ratio (%) of the α-system.

V system rotation speed (m/s).

Specifically, the desired critical speed ratio is set, and the number of revolutions of the dryer is determined by Equations 3 and 4.

Nc=42.2/D ^1/2 . . . Equation 3

N=V/Vc×Nc. . . Equation 4

N-system rotation number (r.p.m.), V-system rotation speed (m/s), Vc-system critical speed (m/s), and Nc-based critical rotation number (r.p.m.).

10‧‧‧Rotating cylinder

31‧‧ ‧ collection chamber

31A‧‧‧ partition wall

33‧‧‧ collecting tube

33A‧‧‧Part 1 (Pipe)

33B‧‧‧Part 2 (Collector)

34‧‧‧Drainage path

R‧‧‧Rotation direction

Θ‧‧‧ tilt angle

Claims (8)

A rotary dryer with an indirect heating tube, comprising: a rotating cylinder; a plurality of heating tubes disposed in the rotating cylinder; a rotary driving mechanism that rotates the rotating cylinder around a central axis thereof; a portion disposed on one end side of the rotating cylinder; and a dry matter discharge portion disposed on the other end side of the rotating cylinder; and the rotary drying machine with the indirect heating tube is configured such that the dried object is in the rotating cylinder In the process of moving the supply unit to the discharge unit, the indirect heating is performed by the heat of the heating medium flowing through the heating tube group, and is formed in the axial end portion of the rotating cylinder. a condensate chamber that communicates with an opening of the end portion of the heating tube group, and a plurality of liquid collecting chambers that are located radially outward of the condensate chamber and that communicate with the condensate chamber and are separated in the circumferential direction, and connect the set The liquid chamber and the liquid collecting pipe provided on the discharge path of the center axis core side guide the condensate of the heating medium from the liquid collecting chamber to the discharge path. The rotary dryer of the indirect heating pipe according to claim 1, wherein the liquid collecting pipe is oriented toward the outer side of the rotating cylinder end, and the front end side of the liquid collecting chamber side and the base end side of the discharge path side are oriented Bending on the side opposite to the direction of rotation of the above rotating drum. The rotary dryer of the indirect heating tube of claim 1, wherein the liquid collecting pipe comprises: a first portion extending outside the side of the liquid collecting chamber; and a second portion connecting the first portion and discharging The path extends in the radial direction of the rotating cylinder. The rotary dryer according to claim 3, wherein the first portion and the second portion are bent toward a side opposite to a rotation direction of the rotating cylinder when viewed from an outer side of the rotating cylinder end. A rotary dryer equipped with an indirect heating pipe according to claim 1, wherein the liquid collecting chamber is partitioned by a partition wall, and the front end of the liquid collecting pipe communicates before the partition wall. The rotary dryer of the indirect heating tube according to claim 1, wherein the liquid collecting chamber is partitioned by a partition wall which is located in front of a rotating direction of the rotating drum in a direction in which the object to be dried is in the axial direction of the rotating cylinder And the side of the object to be dried in the axial direction of the rotating cylinder is inclined so as to be located behind the rotating direction; and the liquid collecting pipe includes a first portion extending outside the side of the liquid collecting chamber, and the first portion is The angles at which the inclination angles are substantially the same are inclined, and the front end of the liquid collection tube communicates before the separation wall. The rotary dryer of the indirect heating tube of claim 6, wherein the angle of inclination formed between the cross sections is 30 degrees to 80 degrees. A drying method using a rotary dryer equipped with an indirect heating tube, which uses a rotary dryer equipped with an indirect heating tube according to any one of claims 1 to 7, to dry the dried object.