GB1561029A

GB1561029A - Rotary drum agglomerator having a pair of independently driven drums

Info

Publication number: GB1561029A
Application number: GB30261/77A
Authority: GB
Original assignee: Dravo Corp
Current assignee: Dravo Corp
Priority date: 1976-07-28
Filing date: 1977-07-19
Publication date: 1980-02-13
Also published as: AU2712777A; DE2733591A1; FR2359637B3; BE857234A; ZA774339B; FR2359637A1; AU505250B2; JPS5316002A

Description

(54) ROTARY DRUM AGGLOMERATOR HAVING A PAIR OF INDEPENDENTLY DRIVEN DRUMS (71) We, DRAVO CORPORATION, a corporation of the Commonwealth of Pennsylvania, United States of America, of One Oliver Plaza, Pittsburgh, Pennsylvania 15222, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a rotary drum agglomerator for forming an agglomerated product from agglomerative materials and more particularly to a rotary drum agglomerator having a pair of driven drum members.

In the process of refining coal and the production of coking coal and formcoke, particulate bituminous coal and finely divided char (the solid carbonaceous residue of coal which has been distilled at a temperature of between 800s and 14000 F) is introduced into a rotary drum. Dependent on the type of coal employed and the ratio of coal to char, pitch may also be added as a binder and to increase the strength of the agglomerates formed in the process. The preheated coal and char supply, as sensible heat, substantially all the heat required to achieve the desired temperature for agglomerating the carbonaceous materials.

The materials are intimately mixed by rotation of the drum. As the constituents are mixed, the coal particles are further heated to such an extent that partial distillation of the coal particles occurs, evolving tar and forming a loosely coherent, plastic sticky mass in the rotary drum. Rotation of the drum breaks up the loosely coherent, plastic mass into relatively fine plastic particles which grow in size as a result of the rolling action of the plastic mass of particulate material in the drum during the mixing or ball forming stage. The rate of flow of agglomerative materials through the drum and the rotational speed of the drum are two of the conditions which determine the size of the agglomerated product.

The agglomerates will continue to grow until the binder evolved by the coal particles and the pitch binder, if employed, loses its plasticity. Thereafter, the agglomerates in the drum rigidify or harden to form uniformly sized particles that are discharged from the outlet portion of the drum.

It is of primary importance that the agglomerated product formed be uniformly sized, preferably in the range of between 1 to 9 winches. Agglomerates having a size greater than about 2 inches and a size less than about 3- inches are considered unsuitable for use in a conventional blast furnace or other conventional metallurgical processes.

Rotary drums for agg1Omerating finelv divided, solid material are known in which a single drum is utilized to perform the mixing, forming and hardening of the agglomerative materials to form the agglomerated product. The constituents are introduced into the inlet portion of the rotary drum by the screw conveyors. In the forming zone of the drum, the process steps of mixing, devolatilization, polymerization and balling take place. The agglomerated product passes into the hardening zone where the remaining binder is evolved from the agglomerates, and the agglomerates rigidify as substantially uniform-sized agglomerates. The agglomerated product of a preselected size is discharged from the outlet portion of the rotary drum.

The forming and hardening stages in the production of the agglomerated product require varying operating conditions. For example, during the forming stage, the rotational speed of the drum should be greater than the rotational speed during the hardening stage in order to control the size of the agglomerated product. Principally, the size of the agglomerated product is controlled by the flow of the agglomerative materials through the rotary drum which is dependent upon the rotational speed of the rotary drum. It is not possible to provide variable speed control for the forming and hardening zones of a single rotary drum arrangement.

It is also known to provide a pair of rotary drums which are offset and independently driven to permit control of the size of the agglomerated product. With this arrangement the outlet of the forming drum is connected to the inlet of the hardening drum by a chute through which the agglomerated product passes. The agglomerated product prior to hardening in the hardening drum is very friable and easily crushed.

Thus, a substantial portion of the agglomerated product is crushed during the transfer of the material between the drums as it passes through the chute.

According to the present invention there is provided a rotary drum assembly for forming an agglomerated product from agglomerative materials comprising, a first cylindrical drum member having an inlet portion for receiving the agglomerative materials and an outlet portion for discharging the formed agglomerated product, a feed end breech assembly enclosing and sealing said first cylindrical drum member inlet portion, a second cylindrical drum member having an inlet portion for receiving the agglomerated product from said first drum member and a discharge end portion for discharging the agglomerated product, said first drum member outlet portion extending into said inlet portion of said second drum member, a centre breech assembly surrounding and sealing said first drum member outlet portion and said second drum member inlet portion, a discharge end breech assembly surrounding and sealing said second cylindrical drum member discharge end portion, said feed end breech, centre breech and discharge end breech assemblies enclosing and sealing said first and second drum members to permit a positive pressure to be maintained within said drum assembly, and drive means for independently rotating said first and second drum members at a preselected speed.

Preferably the assembly includes support means positioned longitudinally below the first and second drum members, a first pair of ring members non-rotatably secured to the outer cylindrical surface of said first drum member adjacent said inlet and outlet portions thereof respectively, means positioned on said support means for rotatably supporting said first pair of ring members, first means drivingly connected to said first drum member for rotating said first drum member at a preselected peripheral speed, a second pair of ring members non-rotatably secured to the outer cylindrical surface of said second drum member adjacent said inlet portion and said discharge end portion thereof, means positioned on said support means for rotatably supporting said second pair of ring members and second means drivingly connected to said second drum for rotating said second drum member at a preselected peripheral speed such that said first drum member rotates independently of said second drum member. The assembly can include roller means positioned on the support means rotatably supporting said first and second drum members, and thrust wheels positioned on said support means and arranged in abutting relation with the side portions of said first and second pairs of ring members of said respective drum members, and said thrust wheels operable to maintain said first and second pairs of ring members in contact with said roller means.

The roller means preferably includes trunnion rollers thn are fixed on the support means for rotatably supporting the first and second drum members for independent rotation. Thrust wheels are positioned on the support means and are arranged in abutting relation with the side portions of the first and second pairs of ring members of the respective drum members. The thrust wheels are operable to maintain the first and second pairs of ring members in contact with the trunnion rollers. Separate pairs of drives and motors are mounted on the support means adjacent the first and second drum members. A separate drive ring gear is secured to the outer cylindrical surface of both the first and second drum members.

A pinion gear is drivingly connected to each of the drive motors and is arranged in meshing relation with the respective drive ring gears. Thus, rotation is transmitted from the drive motors through the pinion gears to each drive ring gear and thereby independently rotate the drum members.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the rotary drum assembly that includes separate balling and hardening drums with portions broken away to illustrate the mechanical seals between the respective drums, the rotary scraper in the balling drum, the rakes in the hardening drum and the integral trommel screen, and Figure 2 is a fragmentary view in side elevation of the balling drum outlet portion and the hardening drum inlet portion, illustrating the manner in which the adjacent end portions of the respective drum members are connected and independently rotatably supported.

Referring to the drawings and particu larly Figure 1, there is illustrated a rotary drum assembly generally designated by the numeral 10 that includes a balling drum 12 and a hardening drum 14. The balling drum 12 is longitudinally aligned in tandem relation with the hardening drum 14, and the balling drum 12 has its discharge portion extending into the inlet portion of the hardening drum. A centre breech assembly 16 extends around the discharge end portion of the balling drum 12 and the inlet end of hardening drum 14 and provides a suitable seal for the respective drums to maintain a positive pressure within the drum assembly 10. A feed end breech assembly 18 surrounds the feed end of the balling drum 12 and also has suitable seals to maintain the positive pressure within the drum assembly 10.

A pair of feed screw conveyors 20 and 22 extend through suitable seals in the feed end breech 18 and are arranged to supple agglomerative material, such as coal and char, to the inner portion of the balling drum 12. The discharge end of the hardening drum 14 extends into a discharge end breech assembly 24 which also has suitable seal means to provide positive pressure within the drum assembly 10. A trommel screen 26 is secured to the discharge end of the hardening drum 14 and is positioned within the discharge breech assembly 24.

The discharge breech assembly 24 has a plurality of outlets 28, 30 and 32 for the material agglomerated in the drum assembly 10. The agglomerated product having the desired size consist is arranged to be discharged from the drum assembly 10 through outlets 28 and 30 and the oversized product is discharged through outlet 32.

A rotary scraper assembly generally designated by the numeral 34 is supported within the balling drum 12 and is arranged to control the thickness of the agglomerative materials deposited on the inner wall of the balling drum 12 and as described in our United Kingdom Patent Specification No.

1,455,234, provide ridges and valleys within the balling drum 12 to aid in the mixing and agglomeration of the agglomerative material within balling drum 12.

Positioned within hardening drum 14 are a plurality of rakes 36 that extend radially therein and are arranged to assist in controlling the size consist of the agglomerated material that is rigidified within the hardening drum 14. Suitable drive means rotate the balling drum 12 and hardening drum 14 at different peripheral speeds and rotate the rotary scraper assembly 34 at a preselected speed.

The balling drum 12 is supported on a platform assembly generally designated by the numeral 38 that is pivotally secured at one end to the centre breech assembly 16.

The platform assembly 38 is arranged to change the angle of inclination of the balling drum 12 to thereby control the rate of flow of the agglomerative materials through the balling drum 12. The balling and hardening drums 12 and 14 are so arranged that their longitudinal axes intersect at a location coincident with the pivot axis of the platform assembly 38 so that the platform pivots the balling drum 12 at the intersection of the balling drum and hardening drum axes.

With the above arrangement agglomerative materials as, for example, particulate coal and finely divided char, previously heated to an elevated temperature is introduced through the conveyors 20 and 22 into the balling drum assembly 12. The preheated coal and char are arranged to supply as sensible heat substantially all of the heat required to achieve the desired temperature for agglomerating the carbonaceous materials. An inert atmosphere is maintained within the drum assembly 10, and a positive pressure of between one and three inches water is maintained within the drum assembly 10 by means of the seals provided at the breech assemblies 16, 18 and 24.

The balling drum 12 is rotated at a preselected speed to effect intimate mixing of the constituents and tumbling of the agglomerates as they are formed in the balling drum 12. As the constituents are admixed in the balling drum, the coal particles are further heated to an extent that partial distillation of the coal particles occurs evolving tar and forming a loosely coherent, plastic sticky mass in the balling drum 12. Where desired, a pitch binder may also be supplied to the balling drum 12 to further contribute to the agglomeration of the carbonaceous material within the balling drum. The loosely coherent, plastic mass formed in the balling drum 12 breaks up during tumbling into relatively fine plastic particles. Growth of the plastic particles within the balling drum 12 is attained by a snowballing type of tumbling or rolling action on the upper exposed surface of the plastic mass of particulate material in the balling drum 12.

A portion of the plastic mass is deposited on the inner wall of the balling drum 12 and the rotary scraper 34 controls the thickness of the plastic mass so deposited and further forms ridges and valleys in the deposited material to improve the mixing and tumbling of the particles as they agglomerate. The rotary scraper 34 as illustrated in Figure 1 has a front shaft 31 that is rotatably supported in a bearing 33 mounted on the feed end breech assembly 18. The front shaft 31 has a sprocket 35 nonrotatably secured thereto. A drive motor 37 is mounted adjacent to the feed end breech assembly and is connected through a suit able speed reducer to a drive sprocket 39.

An endless chain 41 is reeved about the sprockets 35 and 39 to rotate the scraper 34 in a direction opposite to the direction of rotation of the drum 12.

The agglomerates so formed within the balling drum 12 continue to grow until the binder evolved by the coal particles and pitch, if employed, loses its plasticity. The agglomerates so formed are conveyed by the rotation of the balling drum 12 into the hardening drum 14. In the hardening drum 14 the remaining binder is evolved from the agglomerates, and the agglomerates rigidify in the hardening drum 14 as substantially uniformly sized agglomerates.

The rotation of the hardening drum 14 conveys the rigidified agglomerates to the trommel screen 26 where agglomerates of a preselected size are discharged through the openings in the trommel screen and through outlets 28 and 30.. The oversized agglomerates that do not pass through the openings in the trommel screen 26 are discharged through the opening 32. The oversized agglomerates may be crushed and recycled as a constituent of the feed introduced into the balling drum 12. The product of the preselected size recovered through outlets 28 and 30 is thereafter calcined in a calcining vessel at an elevated temperature of between 1 5000F and 1 8000F to form a formcoke that has strength and abrasion resistance that is equal or superior to that of conventional blast furnace coke.

The balling drum 12 has a generally cylindrical configuration with an inlet end portion 40 and an outlet end portion 42 as illustrated in Figures 1 and 2. A suitable insulation material 44 may be positioned on the outer surface of the drum body portion 46 to reduce heat loss through the wall of the balling drum 12 during the agglomeration process. The balling drum 12 has a pair of steel tires or riding rings 48 and 50 ad jacent the inlet end portion 40 and the discharge end portion 42. A drive ring gear 52 is secured to the outer surface of the balling drum 12 between the rings 48 and 50.

The centre breech assembly 16 is supported on a fixed pad 54 and the front end of the platform 38 is supported on a second fixed pad 56. The platform assembly 38 includes a frame member 58 positioned beneath the balling drum 12. Mounted on the frame member 58 is a separate balling drum drive assembly generally designated by the numeral 60 that includes a drive motor 62. a reducer 64 and a pinion gear 66 that meshes with the drive ring gear 52. The riding rings 48 and 50 are supported on pairs of trunnion rollers 68 and 70 with suitable thrust wheels 72 abutting the sides of ring 50 as illustrated in Figure 2.

As illustrated in Figure 2, the longitudinal axis 74 of balling drum 12 intersects the longitudinal axis 76 of the hardening drum 14. The hardening drum 14 has a generally cylindrical configuration with an inlet end portion 78 and an outlet end portion 80.

The hardening drum 14 includes a body portion 82 with a suitable layer of insulation material secured thereto to reduce heat transfer therethrough during the agglomeration process. A pair of steel tires or annular rings 84 and 86 are secured to the hardening drum body portion 82 adjacent the inlet and outlet end portions. Pairs of trunnion rollers 88 and 90 are supported on fixed pads 92 and 94 and rotatably support the hardening drum 14. Thrust wheels 96 maintain the ring 84 in operative position on the trunnion roller 88, as illustrated in Figure 2. The pads 92 and 4 are so constructed to provide the desired angle of inclination for the hardening drum 14.

The hardening drum body portion 82 has a ring gear 98 secured thereto adjacent the ring 84. A hardening drum drive assembly generally designated by the numeral 100 is supported on the pad 92 and includes a motor 102, a reducer 104 and a pinion gear 106 meshing with the ring gear 98. With this arrangement, the hardening drum 14 may be rotated at a preselected speed that is independent of the speed of rotation of the balling drum 12. In this manner the speed of rotation of each drum is independently.

adjustable. Secured to the inner wall of hardening drum body portion 82 are a plurality of rakes 36 that have inwardly extending tines 108. The rakes 36 extend longitudinally throughout a portion of the hardening drum 14 and are arranged as described in United States Patent 3,628,012 and United States Patent 3,460,195 to control the size consist of the agglomerates during the hardening process and before the agglomerates have rigidified.

As illustrated in Figure 2, the rotary scraper 34 has a rear shaft 110 that is supported in a pillow block bearing 112 within the balling drum 12 adjacent the balling drum outlet portion 42. The pillow block bearing 112 is supported by a transverse beam member 114 that is positioned within the hardening drum 14 beyond the balling drum outlet end portion 42. The transverse beam member 114 is positioned within the hardening drum 14 beyond the balling drum outlet end portion 42 and is fixed relative to the centre breech assembly 16. It should be noted that the outer diameter of the balling drum 12 is smaller than the inner diameter of the hardening drum 14 so that the discharge end portion 42 of balling drum 12 extends into and beyond the inlet end portion 78 of hardening drum 14. This arrangement facilitates the transfer of the friable agglomerated material from the balling drum 12 to the hardening drum 14 with a minimum degradation of material during the transfer. The transverse beam member 114 has a forwardly extending portion 116 that extends into the rear discharge portion of balling drum 12, and the pillow block bearing 112 is secured to and supported on the forwardly extending portion 116. With this arrangement, the rear bearing 112 is positioned within the balling drum 12 and remains fixed relative to the independently rotating drum 12 and 14.

A method for forming an agglomerated product from agglomerative materials in a pair of tandemly connected drum members is described and claimed in our copending United Kingdom Patent Application No.

20729/77 (Serial No. 1,554,387).

A rotary drum assembly for forming an agglomerated product from agglomerative materials is described and claimed in our copending United Kingdom Patent Application No. 28319/77 (Serial No. 1,561,030, and in our copending United Kingdom Patent Application No. 29269/77 (Serial No. 1,561,028).

WHAT WE CLAIM IS:- 1. A rotary drum assembly for forming an agglomerated product from agglomerative materials comprising, a first cylindrical drum member having an inlet portion for receiving the agglomerative materials and an outlet portion for discharging the formed agglomerated product, a feed end breech assembly enclosing and sealing said first cylindrical drum member inlet portion, a second cylindrical drum member having an inlet portion for receiving the agglomerated product from said first drum member and a discharge end portion for discharging the agglomerated product, said first drum member outlet portion extending into said inlet portion of said second drum member, a centre breech assembly surrounding and sealing said first drum member outlet portion and said second drum member inlet portion, a discharge end breech assembly surrounding and sealing said second cylindrical drum member discharge end portion, said feed end breech, centre breech and discharge end breech assemblies enclosing and sealing said first and second drum members to permit a positive pressure to be maintained within said drum assembly, and drive means for independently rotating said first and second drum members at a preselected speed.

2. A rotary drum assembly as claimed in claim 1, in which said first drum member is rotatably supported for rotation at a preselected speed, said second drum member being rotatably supported for rotation at a preselected speed, and separate drive means for independently changing the speed of rotation of said first drum member and said second drum member.

3. A rotary drum assembly as claimed in claim 1 or claim 2, including support means positioned longitudinally below said first and second drum members, a first pair of ring members nonrotatably secured to the outer cylindrical surface of said first drum member adjacent said inlet and outlet portions thereof respectively, means positioned on said support means for rotatably supporting said first pair of ring members, first means drivingly connected to said first drum member for rotating said first drum member at a preselected peripheral speed, a second pair of ring members nonrotatably secured to the outer cylindrical surface of said second drum member adjacent said inlet portion and said discharge end portion thereof, means positioned on said support means for rotatably supporting said second pair of ring members, and second means drivingly connected to said second drum for rotating said second drum member at a preselected peripheral speed such that said first drum member rotates independently of said second drum member.

4. A rotary drum assembly as claimed in claim 3, including, roller means positioned on said support means for rotatably supporting said first and second drum members, and thrust wheels positioned on said support means and arranged in abutting relation with the side portions of said first and second pairs of ring members of said respective drum members, and said thrust wheels operable to maintain said first and second pairs of ring members in contact with said roller means.

5. A rotary drum assembly as claimed in claim 1, in which said drive means includes a pair of motor assemblies positioned adjacent said first and second drum members, respectively, and gear means nonrotatably secured to the periphery of said first and second drum members and drivingly connected to said pair of motor assemblies for transmitting rotation therefrom to said drum members.

6. A rotary drum assembly as claimed in claim 5, including a drive ring gear secured to the outer cylindrical surface of said first and second drum members, a pinion gear meshing with said drive ring gear of each of said drum members, and said pinion gear drivingly connected to each of said respective motor assemblies such that each of said drum members may be rotated at a preselected speed independent of the speed of rotation of the other drum member.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

drum 12 to the hardening drum 14 with a minimum degradation of material during the transfer. The transverse beam member 114 has a forwardly extending portion 116 that extends into the rear discharge portion of balling drum 12, and the pillow block bearing 112 is secured to and supported on the forwardly extending portion 116. With this arrangement, the rear bearing 112 is positioned within the balling drum 12 and remains fixed relative to the independently rotating drum 12 and 14.

A method for forming an agglomerated product from agglomerative materials in a pair of tandemly connected drum members is described and claimed in our copending United Kingdom Patent Application No.

20729/77 (Serial No. 1,554,387).

A rotary drum assembly for forming an agglomerated product from agglomerative materials is described and claimed in our copending United Kingdom Patent Application No. 28319/77 (Serial No. 1,561,030, and in our copending United Kingdom Patent Application No. 29269/77 (Serial No. 1,561,028).

WHAT WE CLAIM IS:- 1. A rotary drum assembly for forming an agglomerated product from agglomerative materials comprising, a first cylindrical drum member having an inlet portion for receiving the agglomerative materials and an outlet portion for discharging the formed agglomerated product, a feed end breech assembly enclosing and sealing said first cylindrical drum member inlet portion, a second cylindrical drum member having an inlet portion for receiving the agglomerated product from said first drum member and a discharge end portion for discharging the agglomerated product, said first drum member outlet portion extending into said inlet portion of said second drum member, a centre breech assembly surrounding and sealing said first drum member outlet portion and said second drum member inlet portion, a discharge end breech assembly surrounding and sealing said second cylindrical drum member discharge end portion, said feed end breech, centre breech and discharge end breech assemblies enclosing and sealing said first and second drum members to permit a positive pressure to be maintained within said drum assembly, and drive means for independently rotating said first and second drum members at a preselected speed.
2. A rotary drum assembly as claimed in claim 1, in which said first drum member is rotatably supported for rotation at a preselected speed, said second drum member being rotatably supported for rotation at a preselected speed, and separate drive means for independently changing the speed of rotation of said first drum member and said second drum member.
3. A rotary drum assembly as claimed in claim 1 or claim 2, including support means positioned longitudinally below said first and second drum members, a first pair of ring members nonrotatably secured to the outer cylindrical surface of said first drum member adjacent said inlet and outlet portions thereof respectively, means positioned on said support means for rotatably supporting said first pair of ring members, first means drivingly connected to said first drum member for rotating said first drum member at a preselected peripheral speed, a second pair of ring members nonrotatably secured to the outer cylindrical surface of said second drum member adjacent said inlet portion and said discharge end portion thereof, means positioned on said support means for rotatably supporting said second pair of ring members, and second means drivingly connected to said second drum for rotating said second drum member at a preselected peripheral speed such that said first drum member rotates independently of said second drum member.
4. A rotary drum assembly as claimed in claim 3, including, roller means positioned on said support means for rotatably supporting said first and second drum members, and thrust wheels positioned on said support means and arranged in abutting relation with the side portions of said first and second pairs of ring members of said respective drum members, and said thrust wheels operable to maintain said first and second pairs of ring members in contact with said roller means.
5. A rotary drum assembly as claimed in claim 1, in which said drive means includes a pair of motor assemblies positioned adjacent said first and second drum members, respectively, and gear means nonrotatably secured to the periphery of said first and second drum members and drivingly connected to said pair of motor assemblies for transmitting rotation therefrom to said drum members.
6. A rotary drum assembly as claimed in claim 5, including a drive ring gear secured to the outer cylindrical surface of said first and second drum members, a pinion gear meshing with said drive ring gear of each of said drum members, and said pinion gear drivingly connected to each of said respective motor assemblies such that each of said drum members may be rotated at a preselected speed independent of the speed of rotation of the other drum member.
7. A rotary drum assembly for forming

an agglomerated product from agglomerative materials, substantially as hereinbefore described and with reference to and as illustrated in the accompanying drawings.