FI87692C - Rotating drum - Google Patents

Abstract

Indirectly heated rotary drums are equipped with heat exchange elements which are flowed through by a heat transfer medium. The large number of heating channels necessary with the associated connections, supports, lead-throughs etc. gives rise to considerable production outlay. These rotary drums are thus expensive. As a result of the complicated working cycles, they must as a rule be completely assembled in the workshop. Assembly on site is hardly possible. The new rotary drum is cheaper and easier to assemble. The heat exchange elements are designed as pipe panels (18). The rotary drum is especially suitable for drying and cooling bulk materials, in particular drying wood chips (Fig. 1). <IMAGE>

Description

1 37692

Rotary Drum

The invention relates to a rotary drum according to the preamble of claim 1.

5 In recent years, circulating drums for the heat treatment of bulk products by means of indirect heat transfer have attracted increasing interest, particularly in drying technology, because the amount of exhaust gas obtained is - considerably lower and easier to clean than 10 directly heated dryers.

U.S. Pat. No. 2,267,259 discloses a rotary tumble dryer with tubular plates. However, the tubular plates are bent, which is technically cumbersome and expensive to manufacture. In addition, they are fitted obliquely to the end of the drum jacket and are provided with threaded connections, which makes installation difficult.

DE patent publication 11 74 264 describes a rotary drum suit dryer in which the heat exchange elements are made as individual tubes arranged at relatively large distances from each other.

DE-A-22 41 264 relates to a tumble dryer comprising an outer cylinder and an inner cylinder. Gutter-shaped, i.e. heating circles with a semicircular cross-section are arranged on the inner side of the outer cylinder and on the outer surface of the inner cylinder. In addition, the outer cylinder and the inner cylinder are provided radially; with internally projecting vanes, each of which is also provided with at least one trough-shaped heating channel.

DE-A-33 02 598 describes a tumble dryer with a plurality of parallel heating walls. Each heating wall consists of a number of closely spaced tubes, but apparently not longitudinally welded to each other.

35 2 87692 In connection with these dryers, the number of heating channels required, with their associated connections, supports, bushings, etc., entails considerable manufacturing costs. Therefore, these dryers are relatively expensive. Due to the complexity of the work steps, the dryers usually have to be assembled completely in a workshop; especially in the case of high-volume dryers, the desired on-site installation is hardly possible. Therefore, the volume of such dryers is limited for transport reasons.

Another dryer according to the preamble of claim 1 is known from DE-A-701 070. This dryer has a cylindrical core and a number of radial heating channels which are made of apparently flat double walls flowing through the heating medium. Between the heating ducts there are ducts of sector cross-section, longitudinal, intended for the material to be dried. However, the practical implementation of this drum, which in principle seems simple, encounters considerable structural and manufacturing problems, above all due to the large volume of the drum.

German publication Schweissen und Schneiden,. . ·. volume 17 (1965), number 2, the article on pages 70 - 75 25 deals with welded pipe walls. The article explains the different types of construction that differ in different manufacturing methods. A common characteristic is that the pipe wall comprises a plurality of axial pipes and that there is always a spacer between the two adjacent pipes. Pipe walls that have been conventionally used as gas-tight fireproof walls in steam boiler construction for decades are manufactured in fully automatic welding equipment. They are thus characterized by very strict dimensional tolerances and are relatively inexpensive.

3,87692

The object of the invention is to provide a rotary drum of the quality indicated in the preamble of claim 1, which is simpler and cheaper to manufacture and which can be installed on site from 5 parts made in advance.

This object is solved by the characterizing part of claim 1.

By fitting the interior of the drum according to the application, it is divided into numerous sector-like chambers. This provides a more efficient and even heat transfer to the bulk, which in use is distributed in the individual chambers.

In the embodiment according to the application, the U-shaped fittings can be welded together in the workshop; in order to connect the prefabricated pipe plates to the manifolds 15, only two pipe welding seams are required for each pipe plate. This is particularly advantageous when the installation takes place on site.

The feature of claim 2 likewise facilitates installation.

The feature of claim 3 is recommended for dryers with very high drying power.

The object of the drawing is to illustrate the invention in a simplified manner with the illustrated embodiments. using characters.

Figure 1 shows a rotary drum according to the invention in longitudinal section.

Figure 2 shows a section along the line II-II in Figure 1 or Figure 4.

Figure 3 shows a detail of Figure 2 on an enlarged scale.

Figure 4 shows another rotating drum according to the invention in longitudinal section.

a rotary drum shown in Figure 1 has a housing 1 on which are mounted two sliding frame 2, 3, input line "35 4 87 692 end wall 4 and the outlet-side end wall 5 is firmly connected to the housing 1. Rotary drum is mounted in a conventional manner on rolls, and it has a drive means rotatable about a horizontal or gently inclined around its axis 5. Bearings and actuators are not part of the invention and are therefore not shown in the drawings.

The stationary cylindrical housing 6, in which the helical transport member 7 is rotatably and operatively mounted, coaxially pierces the end wall 4 and 10 is sealed at its circumference in this respect. The housing 6 is provided on the upper side with two lugs 8, 9, one of which is intended to be connected to an air duct and the other to be connected to a device for introducing the material to be treated. A short main area 15 in the vicinity of the end wall 4 is made into a distribution chamber 10. Here, several strips 11 are arranged on the inner side of the jacket 1 - evenly distributed on the circumference; the strips can be arranged axially or also in the form of a helical line. Otherwise, the distribution chamber 10 is free of internal structures.

Near the other end of the drum, the jacket 1 is provided with a plurality of openings 12 distributed around the circumference. Each opening 12 is surrounded by a collar-like edge 13 which protrudes from the inside of the drum and is intended to dam cellular material. The collar can also be height-adjustable in the usual way. In the area of the openings 12, the circulating drum is surrounded by a housing, the lower part of which is made as a discharge funnel 14. The housing has an exhaust air line connection 15 at the top.

A coaxial central tube 17, closed on both sides, is fitted to the interior of the drum by means of sides 16. Its diameter is about 20% of the diameter of the drum. A plurality of tube plates 18 are arranged between the central tube 17 and the jacket 1 so that the longitudinal direction is parallel to the drum axis and the transverse direction is radial. The tube plates 18 extend from the distribution chamber 10 to the zone of the belt in which the openings 12 are fitted. They protrude from both sides just over the ends of the center tube 17. From the second longitudinal side, each tube plate 18 is fastened to the sheath 1 by zinc-like, removable fastening members 5 to the sheath 1, and from the other longitudinal side to the central tube 17.

Each tube plate 18 comprises a plurality - for example eight - of longitudinally oriented tubes 21, which are connected to one another along their entire length by means of flat spacers 22 welded in between. Attached to a few intermediate strips 22 are wing-like, curved lifting weights 23. The individual tubes 21 of the tube plate 18 are connected by means of U-shaped connecting pieces 24 welded to the tube ends in a zigzag-shaped channel. The ends of the outer tube and the inner tube facing the end wall 5 of the discharge side 15 are each connected by a corner-folded connecting piece 25, 26 to the tube seat 27 and the like. 28, which starts from the annular outer distribution channel 29 and the inner distribution channel 30 and extends in the axial direction 20. The outer runner 29 is fixed to the fixing means 31, the outlet side end wall 5, and 32 connected by a plurality of radial channels to the outer tube 33, which - coaxially with respect to the drum axis - to pierce the outlet side end wall 5 and with respect to the end wall 25 stationary.

The inner distribution channel 30 is likewise fixed by fastening members 34 to the end wall 5 and connected via a plurality of radial channels 35 to an inner tube 36 coaxially in the outer tube 33. Between the outer tube 33 and the inner tube 30 there is a channel 37 with an annular cross-section. is mounted in a known manner outside the rotating drum on the sealing head 38. The interior of the inner tube 36 can be connected via a nozzle 39, the channel 37 via the nozzle 40 to the circulation of the heat medium 35.

6,87692

The rotary drum shown in Fig. 4 differs from the rotary drum described so far, in particular in that it has two longitudinal heating zones 41, 42. Each of these heating zones is provided with a plurality of tube plates 18 The central tube 17 extends substantially the entire length of the drum. Between the two heating zones 41, 42 is an additional distribution zone 43 provided with strips 44. The connections for connecting the heating medium to the circulation are arranged at the drum ends and otherwise correspond to the character of your embodiment first described. Due to the fitting of the connections at both ends, the material to be treated and the carrier air must be supplied through 15 drum casings. For this purpose, an extraction device 45 of known construction is arranged at one end of the drum. The second drum end is - as in the case of the first-described exemplary embodiment - surrounded by a housing provided with a discharge funnel 14 and an exhaust air plug 15.

Claims (3)

A rotating drum for heat treatment of bulk goods by indirect heat transfer, said drum comprising 5 heat exchanger elements arranged within a sheath (1) and constructed as pipe plates (18), each comprising a plurality of tubes (21) which are parallel to each other. with the shaft of the drum and which are connected to each other by means of U-shaped connectors (24) to form a zigzag-shaped channel, characterized in that a coaxial core tube (17) is provided within the male end (1) from which the tube plates (18) extends radially leaking all the way to the male ends (1), and the U-shaped connection pieces (24) are welded to the tubes (21). 2. A rotating drum according to claim 1, characterized by releasable fasteners (19,20) for the tube plates (18). Rotating drum according to claim 1 or 2, characterized by longitudinal cross-sections, arranged next to each other, with heating zones (41, 42) provided with tubular plates (18).