US3542348A

US3542348A - Directly heated rotary drying drum

Info

Publication number: US3542348A
Application number: US784008A
Authority: US
Inventors: Gerhard Jahn; Jakob Hinterkeuser
Original assignee: Kloeckner Humboldt Deutz AG
Current assignee: Kloeckner Humboldt Deutz AG
Priority date: 1967-12-21
Filing date: 1968-12-16
Publication date: 1970-11-24
Anticipated expiration: 1987-11-24
Also published as: DE1729233A1; BE725834A; FR1594477A

Description

United States Patent I l l I Inventors Appl No. Filed Patented Assignee Priority Gerhard Jahn Hoflnungsthal;

Jakob l-Iinterkeuser, Menden, Germany 784,008

Dec. 16, 1968 Nov. 24, 1970 KIockner-l-Iumboldt-Deutz Aktiengesell schaft Cologne-Deutz, Germany a corporation of Germany Dec. 21, 1967 Germany No. K64,279

DIRECTLY HEATED ROTARY DRYING DRUM 6 Claims, 3 Drawing Figs.

[52] US. Cl 263/33 [51] Int. Cl F27b 7/00 [50] Field of Search... 263/I9C, 32, 33

[56] References Cited UNITED STATES PATENTS 1,860,738 5/1932 Harty et al. 263/33 1,961,314 6/1934 Wall 263/33X Primary Examiner-John J. Camby A1t0mey-Singer,Stern & Carlberg ABSTRACT: An unlined rotary drying drum provided at one end with a replaceable cylindrical sheet metal shell therein which extends within the range of an open flame used for heating.

Patented Nov. 24, 1970 3,542,348

IN VE N TOPS 6e rka'ral Jd 12 5? 7 111126 Hz'nterkezzser w mw fliforneys DIRECTLY HEATED ROTARY DRYINGDRUM The invention relates to improvements in drying drums having 21 directly heated unlined rotary tube, one end of which forms the combustion chamber for an open flame.

The inner jacket for such drums is usually made of sheet steel and in the range of the flame is particularly subjected to the corrosive and erosive effects of the material being dried.

In the interest of a drum having a short length, there is frequently provided a direct heating, i.e. one end of the drum is constructed as a combustion chamber for an open flame. In such a case the corrosive attack on the inner jacket of the drum is particularly severe throughout the range of the flame length. Added thereto is the erosive effect of the drying goods which is especially active in the range of the flame when hard,

sharp-edged goods, such as gravel, are dried by the continuous I flow process. In a drum structure of this type, the material is introduced into the drum in the range of the flame and experience has shown that this can leadto heavy wear on that portion of the jacket that is most exposed to the flames. The repair of a drum which'is burnt through, however, is time consuming and costly. Also, in most cases the damage is only discovered when it becomes visible at the exterior insulation of the drum. When this occurs, an immediate suspension of all operations becomes necessary.

The object of the invention is an improved drying drum whose rotary cylinder is protected against the corrosive action of the flames. In the event of wear, the protective means can be quickly exchanged.

This object is attained by providing the drum with a separate cylindrical steel metal shell which is insertable in one end of the rotary tube and is positioned close to the interior wall thereof and extends along the range of the length of the flame.

Such a sheet metal shell can be stored as a spare part and may conveniently be exchanged during a pause in operations when, according to experience, the life of the shell in use draws to a close. In addition to this advantage, which is important for a continuous production process, it will be noted that no particular demands as to quality are made on the material of the replaceable shell, so that the expense for the initial installation and the spare parts may be kept low.

The replaceable sheet metal shell may be inserted in the rotary tube of the drum with a loose sliding fit. This results in small points or larger areas of contact between the inner wall of the rotary tube and the outer wall of the replaceable sheet metal shell so that heat is transferred to the rotary tube. Still more advantageous is the provision of an air cushion between the rotary tube and the replaceable sheet metal shell, whereby the enclosed air acts as an additional insulation against heat loss.

According to another feature of the invention, cool air may be introduced into the space between the inner wall of the rotary tube and the inserted shell, thereby intensively cooling the replaceable shell and thus prolonging its life. In order to utilize for the drying process the amount of heat absorbed by the cooling air, provision is made that the heated air is introduced into the drying drum by an open outlet of the intermediate space between the rotary tube and the shell which outlet opens toward the rotary tube. The cooling air may also be considered part'of the mixed air. The cooling air is supplied to the rotary tube in any conventional manner by blowing or suction through a suitably formed inlet opening. The open outlet of the space between rotary tube and sheet metal shell is so shaped in view ofthe axial direction of the movement of the drying goods that the latter are prevented from entering into the intermediate space.

The drawings illustrate in each of the FIGS. 1, 2 and 3 in longitudinal section a different example of the drying drum according to the invention.

Referring to FIG. 1, a rotary tube 1 is in known manner mounted at 4 to be rotatable about its horizontally disposed longitudinal axis. It is slowly rotated by a not illustrated drive mechanism. lntothe right hand end of the rotary tube 1, which serves as a combustion chamber, extends a flame 2 furnished by a nozzle 2a of the drum heating. A tubular sheet metal shell 3 is inserted into the rotary tube 1 in the range of the flame 2 in such a manner that it is easily removable, tie. it can be pulled out of the rotary tube 1 in an axial direction. The outer diameter of the tubular sheet metal shell 3 is smaller than the inner diameter of the rotary tube 1 an amount such that there is formed an intermediate annular space 5 between the two parts I and 3. The air in the annular space 5 acts as an insulating layer and protects the inner wall of the rotary tube in the range of the flame against the temperatures that are particularly high in this region. This air space according to FIG. 2 may be sealed at both ends by heat

resistant members

9 and 10 to form a closed annular air chamber 11 acting as a cushion.

Still more effective is the introduction of cool air into the intermediate annular space 5. For this purpose, there is provided near the right-hand end of the shell 3 an inlet opening 6. The cooling air conveyed in a not illustrated manner by high pressure or -by suction absorbs heat and enters the drying drum at a high tempernture by way of, for example, an open outlet 7. If the outlet 7 is arranged in the range of the flame, the heated cooling air may be also be used as mixed air for supporting the combustion. In both cases the heat economy of the process is improved by reducing the exterior losses of heat.

The tubular sheet metal shell 3' may also slidably engage the inner wall of the tube 1 as shown in FIG. 3,

In the illustrated embodiments, the charging of the drum with drying goods takes place at the end where the heating is provided, i.e. the material to be dried is introduced at 8 and then moves in the same direction as the heating gases in the rotary tube 1, toward the left. It is, however, within the scope of the invention to modify the proposed arrangement so as to obtain a drying drum for counterflow operation.

We claim:

1. A drying drum provided with a directly heated unlined rotary tube, one end of which forms the combustion chamber for an open flame, including means or producing an open flame, a separate cylindrical sheet metal shell which is detachably mounted in said rotary tube and extends close to the inner wall thereof and within the range of said flame, and means for introducing the material to be dried into said separate cylindrical sheet metal shell at the end thereof where the flame is arranged.

2. A drying drum according to claim 1, including means for providing an inlet opening for admitting cool air to an annular space between the inner wall of said rotary tube and said sheet metal shell.

3. A drying-drum according to claim 1, including means for providing an inlet opening for admitting cool air to an annular space between the inner wall of said rotary tube and said sheet metal shell, and an outlet opening for said annular space which opens into said rotary tube.

4. A drying drum provided with a directly heated unlined rotary tube, one end of which forms the combustion chamber for an open flame, including means for producing an open flame, a separate cylindrical sheet metal shell which is detachably mounted in said rotary tube, the outer circumference of said sheet metal shell being in slidable engagement with the inner wall of said rotary tube and extending into the range of said flame.

5. A drying drum accordingto claim 4, including contact areas of different size between the inner wall of said rotary tube and the outer circumference of said sheet metal shell.

6. A drying drum according to claim 4, in which the outer circumference of said cylindrical sheet metal shell is spaced from the inner wall of said rotary tube to form an annular space between said shell and tube, and means sealing the ends of said annular space to form a closed annular air cushion therein.