US3363888A

US3363888A - Rotary apparatus for the heating of particulate or granular materials, especially stones for road-making materials

Info

Publication number: US3363888A
Application number: US545002A
Authority: US
Inventors: Nielsen Aage
Original assignee: H Nielsen and Son Maskinfabrik AS
Current assignee: H Nielsen and Son Maskinfabrik AS; Pedershaab Maskinfabrik AS
Priority date: 1965-05-03
Filing date: 1966-04-25
Publication date: 1968-01-16
Anticipated expiration: 1985-01-16
Also published as: SE304303B; DK111117B; DE1534346A1; GB1101174A; BE680125A

Description

Jan. 16, 1968 A. NIELSEN 3,363, 8

ROTARY APPARATUS FOR THE HEATING OF PARTICULATE OR GRANULAR MATERIALS, ESPECIALLY STONES FOR ROAD'MAKING MATERIALS Filed April 25, 1966 Fl-G.1

United States Patent 3,363,888 ROTARY APPARATUS FOR THE HEATING OF PARTICULATE GR GRANULAR MATERIALS, ESPECIALLY STONES FOR ROAD MAKHNG MATERIALS Aage Nielsen, Copenhagen, Denmark, assignor to H. Nielsen & Son Maskinfahrik A/S, Copenhagen, Denmark, a company of Denmark Filed Apr. 25, W66, Ser. No. 545,002 Claims priority, application Denmark, May 3, 1965, 2

5 Claims. Zci. 263-33) ABSTRACT OF THE DISCLOSURE This invention relates to an apparatus for heating particulate or granular materials, such as stones for roadmaking materials, and comprising a rotatably supported drum having at least one feed opening and one discharge opening for the material, means for heating material located within the drum and driving means for rotating the drum about a longitudinal axis thereof.

A known apparatus of this type comprises a stationary feed funnel connecting into a feed opening in one end wall of the drum whilst a stationary discharge chute is provided in a discharge opening in the other end wall. The chute can be tilted on a horizontal axis between an inoperative position wherein it is upwardly inclined as seen from the drum, and a discharge position wherein it is downwardly inclined. In the latter position the portion of the chute disposed inside the drum may operate as a scraping member which catches the material conveyed along the walls of the drum during the rotation thereof and discharges it from the drum.

In this known apparatus it is often extremely diificult to ensure complete emptying of the drum after the termination of a heating operation as at least a few stones are very likely to remain in the drum without being caught by the chute unless it remains in the discharge position for an extended period. After the termination of the heating of a batch of material, it is often desired to change to the treatment of a batch of a different grain size or grading, for example, in conjunction with the production of bituminous road building materials of diifering composition or fineness, and in such case it is an obvious disadvantage that the fresh batch may contain stones of quite a different grain size.

It is an object of the invention to provide an apparatus in which this disadvantage is obviated. According to the invention an apparatus of the kind referred to comprises a drum having a circumferential wall and at least one end well, said discharge opening or openings being located in said circumferential wall of the drum, bafile means located along opposed edge portions of each discharge opening at the inner side and the outer side, respectively, of said circumferential wall and extending from said edge portions in opposite directions circumferentially across and past said opening in spaced relation 3,363,888 Patented Jan. 16, 1968 to said wall, and the driving means for rotating the drum are arranged for selectively reversing the direction of r0- tation of the drum.

The said bafile means define, in conjunction with each discharge opening, a tortuous channel between the inner side and the outer side of the circumferential drum wall, and through this channel the material may be rapidly discharged from the drum during the rotation thereof whereby the leading edge, as viewed in the direction of rotation, of the internal baflle means contributes to scraping the material oif the drum wall. When the drum rotates in the opposite direction, there will be no tendency for the material to escape from the drum through the channel which, on the contrary, will operate to return to the interior of the drum any material that might have entered the channel. Thus, with extremely simple structural and control means it has been made possible to rapidly empty the drum completely of its contents simply by reversing its direction of rotation.

Each discharge opening may be substantially rectangular in plan view and defined by two axially extending edges and two circumferentially extending edges, and the radial spacing between the drum wall and the bafile means may be substantially equal to the dimension of the opening in the circumferential direction of the drum, whereby the cross section of the channel referred to above becomes substantially constant over the entire length of the channel.

The invention will be explained in more detail below with reference to the accompanying diagrammatical drawings, wherein FIG. 1 is a vertical section, taken on line II in FIG. 2, through an apparatus embodying the invention, wherein such parts as are not deemed necessary for under standing the invention, have been omitted, and

FIG. 2 is a section taken on line II-II in FIG. 1.

The apparatus shown in the drawings comprises a drum 1 the circumferential wall of which consists of a cylindrical central portion 2 and two conical end portions 3. One end wall 4 of the drum is provided with a central opening 6, and a stationary disposed feed funnel 7, the support means of which is not shown, extends some distance into the drum through the opening 6. The other end wall 5 of the drum is provided with a central opening 8, and a diagrammatically shown oil burner 9 is, in a manner not shown, supported outside the drum the contents of which are heated by means of the burner flame during operation of the apparatus.

To each end portion 3 of the drum there is secured, for example by welding, a cylindrical ring 10 co-axial with the drum axis, and the rings 10 engage driving wheels 11 as well as supporting means, not shown, for rotatably supporting the drum. The driving rollers 11 which may be coated with a friction-increasing material, such as rubber, are driven by means of reversible electric motors 12.

The central portion 2 of the drum 1 is surrounded by a stationary jacket 13 which beneath the middle portion of the drum has a discharge channel 14, and which diametrically opposite said channel 14 has a flue 15 for removing hot gases from the drum.

In the cylindrical central portion 2 of the drum there are provided a plurality, in the example shown there are six, of discharge openings 16 of substantially rectangular shape. In the longitudinal direction of the drum the openings 16 extend over the major part of the length of the central portion 2. At the inner side and outer side, respectively, of the central portion 2 of the drum a baflie or guide member in the shape of a

vane

17 or 18, respectively, is associated with each opening 16. The vane 17 is secured, for example by Welding, to the inner wall of the drum portion 2 along one longitudinal edge of the opening 16 and thence it extends first in an inclined direc tion towards the interior of the drum, see FIG. 2, and then substantially tangentially, i.e. parallel to the drum wall, across the opening 16 and past the opposite edge thereof. Similarly, the vane 18 is secured to the opposite axial or longitudinal edge of the opening 16 and extends first in an outwards inclined direction from said edge and then parallel to the drum wall across and past the opening 16. As shown, the radial distance between each of the vanes and the associated part of the drum wall is by and large equal to the tangential width of the opening 16. As shown, each

vane

17 or 18 covers a portion of the circumference of the drum section which is substantially equal to half the distance between two successive openings 16. With a view to stiffening the

vanes

17 and 18 they may, as shown, be connected with the drum wall along their axial edges by means of wall portions 19 and 2.0 respectively.

The drum shown may, for example, be used for heating and drying stone material for road surfaces. A weighedoff portion of stones, pre-graded as requested, is fed to the drum through the funnel 7, and then the drum is caused to rotate by starting the motors 12, and the oil burner 9 is ignited. When the material has remained in the drum for a length of time sufiicient for freeing the material of water and for heating it to a desired temperature, which for example may lie between about 70 and 200 deg. centigrade, it is discharged from the drum through the discharge channel 14 and passed on to for example a mixer, not shown, in which the stones are coated and mixed with asphalt or another bituminous binder. In the apparatus described this discharge operation is carried out simply by reversing the direction of rotation of the drum 1.

During the heating of the material, the drum rotates in the direction of arrow A, FIG. 2, and the material contained in the drum will then be incapable of leaving the drum through the channels formed by the openings 16 and the adjoining passages between the drum wall and the

vanes

17 and 18, while the hot gases may escape freely through the channels located above the surface of the material layer and be discharged through the flue 15. When the direction of rotation is reversed, so that the drum rotates in the direction of arrow B, the material will be capable of flowing rapidly out of the drum through said channels. In such case, the vanes 17 operate as guide members which initially scrape the material oif the drum wall and subsequently guide any remaining stones, into the channels. Due to the conical shape of the drum ends 3, the material at the drum ends will quickly find its way to the central portion 2 as soon as the material originally contained in this section of the drum has been discharged through the opening 16. Thus, a rapid and total removal of all material from the drum is attained solely by reversing the direction of rotation of said drum. Consequently, it is also possible without risking unwanted mixing of different materials or without operational interruption for the purpose of separately cleaning the drum, to successively treat charges of mutually widely difiering materials.

What I claim is:

1. Apparatus for heating particulate or granular materials, such as stones for road-making materials, comprising a drum having at least one end wall and a circumferential wall having a cylindrical central portion and two conical end portions; means for rotatably supporting said drum; means for rotating said drum about its longitudinal axis and for selectively reversing the direction of rotation of the drum; at least one feed opening for introducing material into said drum; at least one discharge opening located in said central wall portion; baflle means located along opposed edge portions of said discharge opening at the inner side and the outer side, respectively, of said circumferential wall and extending from said edge portions in opposite directions circumferentially across and past said discharge opening in spaced relation to said wall; and means for heating material located within said drum.

2. Apparatus as claimed in claim 1, wherein said discharge opening is substantially rectangular in plan view and defined by two axially extending edges and two circumferentially extending edges, and the radial spacing between said circumferential drum wall and said baflle means is substantially equal to the dimension of said opening in the circumferential direction.

3. Apparatus as claimed in claim 1 and comprising a plurality of discharge openings in said circumferential wall, wherein the dimensions of each bafile means in the circumferential direction of the drum is substantially equal to one half of the distance between adjacent discharge openings in said wall.

4. Apparatus as claimed in claim 1, wherein said means for rotating said drum comprise reversible electric motors.

5. Apparatus as claimed in claim 1, further comprising a stationary jacket surrounding said central wall portion and adjoining parts of said conical end portions of said circumferential drum wall, a discharge channel opening in the lower middle portion of said jacket, and a gas exhaust conduit extending from the upper middle portion of said jacket.

References Cited UNITED STATES PATENTS 3/1943 Smith 21418 2/1960 Schoonover 263-33