US2276589A - Drier - Google Patents

Description

March 17, 1942 M. F. PELTIER EI'AL DRIER Filed Feb. 20, 1939 2 Sheets-Sheet 2 Me'rr, J8.

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Patented Mar. 17, 1942 DRIER Moses F. Peltier, Chicago, William Burnett, Jr., Marion, and Carl Lee, Chicago, Ill., asslgnors to Peabody Coal Company, Chicago, 11]., a corporation of Illinois Application February 20, 1939, Serial No. 257,418

2 Claims.

The present invention relates in general to driers, and is more particularly concerned with driers for use in the drying of wet materials, especially wet coal.

Due to the increased use by the coal consumer of improved equipment such as automatic stokers for the burning of coal, there has been an increasing demand for high quality coal which is substantially free of impurities. On the other hand, the increased use of mechanical loading equipment by the coal producers results in an increased amount of impurities in the coal products. In order, therefore, for the producer to utilize the mechanical loading equipment and still furnish the consumer with high quality coal, it has become necessary for the producer to provide suitable means for removing the impurities and cleaning the coal. This has been in general accomplished by subjecting the coal to a washing process.

Under ordinary conditions of temperatures, the wet washing of .coal has proved to be very satisfactory but during extremely cold weather the washed coal has the disadvantage of freezing during transit, unless its surface moisture content has been reduced ,to between 1 and 4 percent.

For decreasing the surface moisture content, it has been the usual practice to use some sort of drying apparatus, which in the main has proved unsatisfactory, due to improper design and construction for the handling of coal, wherein problems are presented and conditions encountered which do not attend the handling of most other materials. For example, many of the present driers are so constructed that there is an excessive breakage or degradation of the coal. Moreover, the driers as presently constructed fail to properly apply the heat during the drying process, with the result that surface coking and volatile fuel is driven off the surface of the coal.

Attempts have been made, particularly in driers of the drum type, to improve their operation by the addition of a number of stationary or fixed flights or lifting members in the drum to cause mixing of the coal during the drying operation.

7 These flights have oeen found to be objectionable as they form corners and crevices wherein fly ash and semi-baked material may accumulate and after a time form lumps which drop into the material being dried. In the case of coal, such lumps of high ash coal are objectionable in the finished product. These flights further are objectionable in that a considerable amount of coal is lifted above the drum center line, and

then dropped to the bottom, thus causing increased degradation of the coal.

In order to overcome the foregoing objections as well as other objections to coal drying apparatus heretofore available, the present invention contemplates as a primary object the provision of an improved construction for coal driers of the rotating drum type, wherein the drum is made with a double wall, and in which the coal and heated gas for drying the coal is conducted through the drum within the inner wall, and gas only is conducted through the space between the drum walls. By conducting a portion of the gas through thte space between the walls of the drum,-

the inner wall, which is in contact with the material being dried, is maintained at a higher temperature, heat energy is conserved and radiation losses reduced.

Still another object of the hereindescribed invention is to provide improved means within the drum for turning and mixing the material rather than permitting it to slide along the inner surface of the drum; and also for stirring and lifting the material while it is being dried; as well as assisting in retarding the material flow as desired, depending upon the amount of inclination of the drum, the quantity of material being passed through the drum within a predetermined time,

and the rate of movement of the material. This object is accomplished by the use of flexible members, such as chains, rather than fixed or rigid flights.

Still another object of the invention is to provide an improved drier, particularly adapted for the drying of coal, which is simple in construction and not liable to get out of order, and which is eflicient in operation and will quickly and thoroughly dry the material passed therethrough. While the present invention will be described with particular reference to its use in the drying of coal, it will be appreciated that its features of construction may be utilized to advantage in driers for other materials other than coal. Moreover, it is not intended that the use of the apparatus shall be limited only to the application of heat to the material, since the construction of the apparatus is such as to also enable its advantageous use for the cooling of materials.

Other objects and features of the invention will more fully appear from the following detailed description, taken in connection with the I tion of a drier embodying the features of the hereindescribed invention;

Figure 2 is a detailed view looking at the discharge end of the rotating drum of the drier;

generally indicated at A, supported for rotation upon rollers [0 supported in suitable bearings on a base structure II and engaging tracks l2 on the drum.

The drum is slightly inclined from horizontal with its discharge end at a lower level than its inlet end and is rotated by suitable means including a driving pinion l3 arranged to be driven by a suitable motor I4. this pinion meshing with a: suitable gear IS on the drum. Referring to Figure 3, the drum A comprises an inner tubular metallic shell 5 which is surrounded by an outer shell ii, the outer shell being supported in concentric spaced relation to the inner shell by a plurality of I-members l8 extending longitudinally of the drum. This construction in effect forms a double: walled tubular drum.

Heated gas is delivered to the inlet end of the drum, a portion of the gas passing through the inner shell into which'material such as wet coal has been delivered for drying. Another portion of the gas is conducted through the space between the inner and outer shells where it is in direct contact with the outer surface of the inner shell l6 and serves to maintain this shell at higher temperatures so that heat is conserved and radiation losses reduced. At the discharge end of the inner shell, there is provided a ring shaped head member l3 having a plurality of spaced circumferential openings at its periphery for the discharge of material from the drum, without the necessity of this material having to pass over the inner edge of the end head l9.

For controlling the movement of the material through the inner shell, mixing the material and aiding in the drying thereof, there are provided a plurality of flexible members, in this instance a plurality of chains.

As shown in Figures 3, 4 and 5, the chains are arranged in various manners, depending upon the function to be performed thereby.

For intercepting the material in its longitudinal direction of movement through the drum, and for retarding its movement during the drying operation, there has been. provided at spaced intervals throughout the length of the drum a plurality of generally ring shaped bafiles 2|, as shown in Figure 4. Each of these baffles comprises a plurality of chains 22 which are supported to form concentric spaced apart rings which are supported at spaced intervals by radially extending pins 23 supported at their outer ends from the inner shell Hi. It will be noted that the chains 22 lie in the transverse plane.

of the inner shell. The chains 22 are tightly stretched between their supports.

In addition to the chains 22, other chains as shown at 24 in Figure 3 are provided at the inlet end of the inner shell, these chains being supported from pins similar to the pins 23 just described. It will be noted however that the chains 24 instead of extending circumferentially around the interior of the shell I 6 are arranged to extend longitudinally thereof and are spaced apart circumferentially of the shell.

In addition to the chains 23 and 24, other chains 25., as shown in Figures 3 and 5, are provided, these chains being supported on suitably placed pins 23 and in general having a spiraled direction around the interior of the inner shell IS. The chains 25 operate to provide some counterflow in the movement of the material through the drum. The chains 25 are not tightly stretched between their supporting pins, but are preferably loosely hung so that there will be relative movement of the chains through the material as the drum is rotated. As shown in Figure 5, the chain portions when at the top of the drum will hang downwardly away from the shell i6, and as the drum continues to rotate and bring these portions toward the bottom of the drum, the chains will assume varying positions of sag until at the bottom of the drum they will be lying against the adjacent portions of the shell l6.

The use of chains has been found to be a great improvement over the use of fixed or rigid members, since the chains operate to turn the material rather than permitting it to slide over the inner surface of the inner shell. These chains also operate to lift and stir the material and may be adjusted to various positions depending upon the inclination of the drum, the quantity of the material to be passed through the drum within a certain time, and the rate at which the material is passed through the drum.

Since the chains are flexible they continue to change positions throughout the entire revolution of the drum, thus breaking loose and preventing any possible accumulaticn of fly ash and material. Moreover, as the chains drag through the material they produce a much greater stirring effect than would be possible with fixed or stationary flights. These chains present relatively large surfaces for absorbing heat while being carried through the upper part of the drum so that as they are dragged through the mass of material at the bottom of the drum this heat is imparted to the material during its stirring action by means of the chains.

Yariously arranged apparatus may be provided for supplying the material to be dried to the drum and the hot gas for drying the material, and for removing and separating the gas and material after it has passed through the drum. An arrangement which we have found to work very satisfactorily is disclosed in Figure 1.

Adjacent the inlet end of the drum, there is provided a furnace which may be arranged for the burning of coal dust, this type of furnace giving uniform heat and being quickly responsive to changes in demand. The gas generated in this furnace is forced through a closed housing 21 to the inlet end of the drum by means of a blower 28 of suitable design, which may be driven by a motor 29.

The material such as coal may be delivered to the drum from a hopper 30 supported on the top of the casing 21 adjacent the inlet end of the drum. Material from this hopper flows downwardly over spaced deflectors 32 which are alternately inclined in opposite directions and from which the material flows into a suitable trough 33 communicating with the inlet end of the inner shell I6. Discharge of the material from the hopper 30 is controlled and regulated by means of a suitable gate 34. The hot furnace gas is delivered at the inlet of the drum and a portion of this gas will pass-through the space between the shells I6 and I1, whereas other portions of the gas will pass into the inner shell l6 for direct engagement with the material passing through the drum. The outlet end of the drum is associated with the gas exhaust stack 35 which may be fitted with an inclined bottom wall 36 having an outlet opening 31 through which the dried material may be discharged from the drum onto a suitable conveyor 38 which transmits the dried material to a delivery point away from the discharge end of the drum. If desired, the bottom wall 36 may be provided with a slide gate 39 to permit inspection of the discharge end of the drum.

From the foregoing description it will be ap-' parent that the present invention provides an improved drier of the drum type which is simple in construction and not liable to get out of order, eificient in operation, and which will quickly and thoroughly dry a material passed therethrough; a drier which is especially advantageous for the drying of coal; which includes a double walled drum construction in which the coal and heated gas are conducted through a central axial passageway and gas only is conducted through the space between the drum walls, whereby the imier wall of the drum is maintained at a higher temperature, heat energy is conserved and radiation losses reduced; and a drier which embodies improved means within the drum for mixing the material, said means operating to turn the material rather than permit it to slide, stir and lift the material while it is being dried, and assist or retard the material flow and aid in the distribution of heat through the material while it is being mixed.

It is, ofcourse, to be understood that although we have described in detail the preferred embodiment of our invention, the invention is not to be thus limited, but only insofar as defined by the scope and spirit of the appended claims.

We claim as our invention:

1. In apparatus of the character described, a rotatable drum having an axial passageway for material, a plurality of spirally extending flexible members within said passageway, a plurality of flexible members extending circumferentially in said passageway, a plurality of flexible members extending axially of said passageway and spaced outwardly from the axis thereof, means for supporting said flexible members at spaced intervals along their length, and means for varying the temperature of said material during its passage through said drum.

2. In apparatus of the character described, a rotatable drum having a passageway from one end to its other for movement of material to be treated therein, a plurality of chains supported in the passageway for engaging and mixing the material during its movement through the passageway, certain of said chains extending spirally, others circumferentially. and still others axially of the passageway, and means for varying the temperature of the material during the mixing operation.

MOSES F. PEL'I'IER. WILLIAM BURNETT, JR. CARL LEE.

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