Abstract
A conveyor floor for conveying bulk material like cement clinker in a conveying direction from a bulk material inlet to a bulk material outlet, with longitudinal reciprocating planks which extend in parallel to the conveying direction and are arranged one besides of the other with moving gaps in between provides enhanced conveying at lower costs, if each plank has a mean coefficient of friction C.sub.f for moving of the bulk material in the conveying direction relative to planks being significantly lower than the mean coefficient of friction C.sub.b for moving of the bulk material against the conveying direction relative to the respective plank.
Claims
1. A conveyor floor configured to convey cement clinker in a conveying direction from a material inlet to a material outlet, the conveyor floor comprising: longitudinal planks, each with a corresponding up-facing surface configured as a rest for the cement clinker, said planks extending parallel to the conveying direction and transversely to the conveying direction one besides another with moving gaps in between, a support structure configured to support and reciprocate at least some of said planks, to thereby convey the cement clinker in the conveying direction, wherein: each plank has a mean coefficient of friction C.sub.f, associated with movement of the cement clinker in the conveying direction relative to the respective plank, and a mean coefficient of friction C.sub.b associated with movement of the cement clinker against the conveying direction relative to the respective plank; at least one of said planks has on its up facing surface at least one protrusion, said protrusion having a front facing side and rear facing side, wherein a mean slope of the front facing side is steeper than a mean slope of the rear facing side; a relation C.sub.b/C.sub.f1.5 holds for at least a majority of said planks and a height h of said protrusion is smaller than a mean diameter of the cement clinker grain; and the planks are grouped in exactly two groups of planks, wherein planks forming a first group of planks are driven to reciprocate in parallel to their longitudinal axes and planks of a second group of planks are mounted to a static support structure.
2. A conveyor floor of claim 1, wherein for at least a majority of said planks a relation C.sub.b/C.sub.f2 holds true.
3. A conveyor floor of claim 1, wherein the planks of the first group are neighbored to the planks of the second group to form a pattern of planks reading |A, C, A, . . . A,C,A,| or |C, A, C, . . . , C, A, C|, wherein vertical lines | symbolize boundaries of a grate floor defining a grate floor's width, A and C symbolize a plank of a respective group of planks, and commas represent the moving gaps.
4. A conveyor floor of claim 1, wherein the planks are grouped in exactly three groups of planks, wherein planks forming a first group of planks are driven to reciprocate in parallel to their longitudinal axes in a common phase, and planks forming a second group of planks (i) are driven to reciprocate in parallel to their longitudinal axes in a common phase, (ii) are moved forward simultaneously with the planks of the first group of planks; (iii) are moved backwards non simultaneously with the planks of the first group of planks, planks of a third group of planks are mounted to a static support structure, wherein planks form a pattern reading one of |C, A, C, B, C, . . . , C, A, C, B, C,| and |C, B, C, A, C . . . C, A, C, B, C| and | . . . A, B, C, A, . . . |, wherein A, B, and C denote a plank of a respective group, vertical lines | symbolize boundaries of a grate floor and commas represent moving gaps.
5. A conveyor floor of claim 1, wherein the conveyor floor is a clinker cooler comprising ventilation means configured to blow a cooling gas through the moving gaps into a clinker bed for aeration of the cement clinker.
6. A conveyor floor of claim 1, wherein the moving gaps are formed by facing narrow sides of adjacent planks, wherein one of which evolves at least semi-continuously into a plank's up facing surface.
7. A conveyor floor of claim 6, wherein at least one plank has on its up facing surface at least one series of consecutive protrusions.
8. A conveyor floor of claim 7, wherein at least one front facing side of a protrusion of a plank is inclined towards a narrow side of said plank.
9. A conveyor floor of claim 6, wherein at least one front facing side of a protrusion of a plank is inclined towards a narrow side of said plank.
10. A conveyor floor of claim 6, wherein the at least one of protrusions has an overlap portion spanning over a moving gap, wherein the overlap portion has a down facing surface with a cross section that is curved from a moving gap's inclination towards a horizontal.
11. A conveyor floor of claim 10, wherein the overlap portion has an up facing surface that is a part of the at least one protrusion's rear facing side.
12. A conveyor floor of claim 11, wherein the up facing surface and the down facing surface of the overlap portion meet in one of an edge and edge like curvature that connects a lower edge of a front facing side of a rearward protrusion with a front facing side of the overlap portion.
13. A conveyor floor of claim 6, wherein the at least one of protrusions has an overlap portion spanning over a moving gap, wherein the overlap portion has a down facing surface with a cross section that is curved from a moving gap's inclination towards a horizontal.
14. A conveyor floor configured to convey cement clinker in a conveying direction from a material inlet to a material outlet, the conveyor floor comprising: longitudinal planks, each with a corresponding up-facing surface configured as a rest for the cement clinker, said planks extending parallel to the conveying direction and transversely to the conveying direction one besides another with moving gaps in between, a support structure configured to support and reciprocate at least some of said planks, to thereby convey the cement clinker in the conveying direction, wherein: each plank has a mean coefficient of friction C.sub.f, associated with movement of the cement clinker in the conveying direction relative to the respective plank, and a mean coefficient of friction C.sub.b associated with movement of the cement clinker against the conveying direction relative to the respective planks; at least one of said planks has on its up facing surface at least one protrusion, said protrusion having a front facing side and rear facing side, wherein a mean slope of the front facing side is steeper than a mean slope of the rear facing side; a relation C.sub.b/C.sub.f1.5 holds for at least a majority of said planks and a height h of said protrusion is smaller than a mean diameter of the cement clinker grain; and the moving gaps are formed by facing narrow sides of adjacent planks, wherein one of which evolves at least semi-continuously into a plank's up facing surface.
15. A conveyor floor of claim 14, wherein for at least a majority of said planks a relation C.sub.b/C.sub.f2 holds true.
16. A conveyor floor of claim 14, wherein the planks are grouped in exactly two groups of planks, wherein planks forming a first group of planks are driven to reciprocate in parallel to their longitudinal axes and planks of a second group of planks are mounted to a static support structure.
17. A conveyor floor of claim 16, wherein the planks of the first group are neighbored to the planks of the second group to form a pattern of planks reading |A, C, A, . . . A,C,A,| or |C, A, C, C, . . . , A, C|, wherein vertical lines | symbolize boundaries of a grate floor defining a grate floor's width, A and C symbolize a plank of a respective group of planks, and commas represent the moving gaps.
18. A conveyor floor of claim 14, wherein the planks are grouped in exactly three groups of planks, wherein planks forming a first group of planks are driven to reciprocate in parallel to their longitudinal axes in a common phase, and planks forming a second group of planks (i) are driven to reciprocate in parallel to their longitudinal axes in a common phase, (ii) are moved forward simultaneously with the planks of the first group of planks; (iii) are moved backwards non simultaneously with the planks of the first group of planks, planks of a third group of planks are mounted to a static support structure, wherein planks form a pattern reading one of |C, A, C, B, C, . . . , C, A, C, B, C,| and |C, B, C, A, C . . . C, A, C, B, C| and | . . . A, B, C, A, . . . |, wherein A, B, and C denote a plank of a respective group, vertical lines | symbolize boundaries of a grate floor and commas represent moving gaps.
19. A conveyor floor of claim 14, wherein the conveyor floor is a clinker cooler comprising ventilation means configured to blow a cooling gas through the moving gaps into a clinker bed for aeration of the cement clinker.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In the following, the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment and with reference to the drawings.
(2) FIG. 1 shows a conveyor floor of a clinker cooler.
(3) FIG. 2 shows a longitudinal section of a plank as shown in FIG. 1.
(4) FIG. 3 shows a section of a conveyor floor.
(5) FIG. 4 shows a section of a further conveyor floor.
(6) FIG. 5 shows an example for grouping planks of a conveyor floor.
(7) FIG. 6 shows a second example for grouping planks of a conveyor floor and diagrams reflecting the movement of the planks.
(8) FIG. 7 shows a third example for grouping planks of a conveyor floor.
(9) While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
DETAILED DESCRIPTION
(10) In FIG. 1 a conveyor floor 1 is sketched. The conveyor floor 1 is a grate floor e.g. for cooling and conveying clinker, which can be loaded from a rotary kiln via a clinker distribution system 5 onto the grate floor. The clinker is conveyed from a clinker inlet, i.e. the clinker distribution system 5 in a conveying direction being symbolized by an arrow 2 to a clinker outlet.
(11) The conveyor floor 1 has planks 100 extending in the longitudinal direction (indicated by double headed arrow 3) from the conveyor inlet to the conveyor outlet. The planks 100 are arranged in parallel one beside the other with moving gaps 20 in between. The moving gaps 20 (cf. FIG. 3 and FIG. 4) permit a reciprocating movement of the grate bars 101 of a plank 100 relative to the grate bars 101 of neighbored planks 100 along the longitudinal direction 2 of the grate floor as indicated by double headed arrows 3. In addition a cooling gas may be injected through the moving gaps 20 into a clinker bed being conveyed. Alternatively the same conveyor floor could be used as well for other bulk material, e.g. for corn that can be dried while conveyed by injecting air at a low relative humidity via the moving gaps into a corn layer being deposited on the conveyor floor.
(12) Grate boundaries 30, as well referred to as side walls 30, may be installed to the left and to the right of the planks (FIG. 1). The grate boundaries are preferably clad by some refractory material. The planks 100 next to the side walls 30 are preferably fixed relative to the respective side wall 30. In other words the planks next to the side wall 30 preferably do not reciprocate.
(13) The planks 100 are designated A, B, C, indicating a group they belong to. The planks 100 of each group A, B, C are mounted to separate cross beams 40. The cross beams 40 carrying the planks of groups A and B are suspended and driven to reciprocate as indicated by the arrow 3. The cross beams 40 supporting the planks of group C are fixed, i.e. they are rigidly mounted to a base, e.g. by some static support structure. The pattern A,B,C as depicted is only an example. Other patterns, or in other words other sequences of groups are as well possible, for example |C,A,C,A . . . C| or |C, B, C, A, C, B, . . . ,C| to list only two.
(14) As shown in FIG. 2, FIG. 3, and FIG. 4, the planks 100 may have protrusions 10 forming a shingled surface as apparent. The protrusions 10 may for example have an approximately triangular longitudinal section (FIG. 2) with steep front facing side 12 facing in the conveying direction, i.e. towards the clinker outlet, and a gently sloping rear facing side 14. In the depicted example the front facing side is orthogonal to the conveying direction 2, but other angles are possible as well, provided that the mean slope of the front facing side is steeper than the mean slope of the gently sloped rear facing side 14. When moving the plank 100 in the conveying direction, the front facing side 12 acts like a block. Accordingly the grains of the bulk material are pushed forward by the forward movement of the plank. When retracting the plank, the grains of the bulk material slide over the ramp being formed by the rear facing side 14. Thereby, in a macroscopic view the coefficient of friction C.sub.f for a forward movement of a bulk material, like cement clinker, relative to the plank is smaller as the coefficient of friction C.sub.b for a backward movement of the same bulk material relative to said plank. The height h of the crest 11 and the length l.sub.r of the ramp have been optimized by extensive experiments with clinker. Astonishingly it turned out, that an optimized ratio of C.sub.b/C.sub.f can be realized with comparatively low crest 11 height h of only 3/10 of the typical grain diameter d.sub.g1 cm (possible 0.1 d.sub.ghd.sub.g, preferably 0.1 d.sub.gh0.5 d.sub.g). The optimum ramp l.sub.r length was found to be about 3 to 4 times the typical grain diameter d.sub.g (possible 1.5 d.sub.gl.sub.r7 d.sub.g, preferably 2.5 d.sub.gl.sub.r5 d.sub.g). The median of the grain diameters can be considered as typical grain diameter.
(15) In FIG. 3 three planks 100 of a conveyor floor are shown, for example of a grate floor as sketched in FIG. 1. On each plank 100 are protrusions 10, as well referred to as elevations 10. The protrusions 10 each have a crest 11 from their left to their right (referring to the conveying direction 2). The longitudinal sections (cf. FIG. 2) of the protrusions 10 resemble triangles (the dotted line is a guide to the eyes). Each protrusion 10 has a front facing side 12 and rear facing side 14, where front and rear refer as well to the conveying direction 2. The front facing sides 12 have a steeper slope (as example almost 90 to the longitudinal axis) as the rear facing side (for example about 20, possible 2 to 35, preferred between 2 and 10). The height of the protrusions is symbolized by h. When pushing the planks A and/or B forward, the front facing sides 12 of the protrusions 10 work like a block being pushed forward, i.e. the clinker grains are as well moved in the forward direction. To this end, the height h of the protrusions 10, is preferably about 0.3 times the mean diameter of the clinker particles. When retracting preferably group A (or B) after group B (or A), the front sides 12 of the groups of planks B, C (or A, C) that are not retracted, block the clinker bed from following the retracted plank A. Instead, the clinker so to speak climbs up the gently sloped rear facing side 14 of the protrusion on plank A (or B).
(16) For a homogeneous aeration of the clinker, the moving gaps 20 are inclined against the vertical. For forming the inclined moving gap 20 each plank has a first narrow side with an inclined upper surface 21 and a second narrow side 22 with a complementary undercut. The upper surface 21 and the second narrow side are preferably parallel. Preferably, the protrusion 10 extends smoothly from the first narrow side as shown in FIG. 3 and FIG. 4. The transition from the first narrow side 21 to the gently sloped rear sides 14 of the protrusions 10 is preferably continuously curved, to thereby better attach the coolant to the rear side 14 of the protrusion 10. To even better attach the coolant to the rear side 14 of the protrusion 10 the protrusion 10 may have an overlapping portion 16, overlapping the gently sloped rear facing side 14 of the neighbored protrusion as shown in FIG. 4.
(17) As shown in FIG. 4, the protrusion 10 has a curved surface 17 continuing the inclined moving gap 20 to thereby improve attachment of the cooling gas flow to the surface 14 of the neighbored plank 100. A homogeneous aeration of the clinker bed is thereby further enhanced as well as transportation of clinker dust particles to the upper region of the clinker bed. In the cross section, the protrusion 10 is preferably continuously curved to thereby provide an accordingly curved moving gap 20.
(18) The grate floor in FIG. 4 is similar to the grate floor as shown in FIG. 2 and FIG. 3, the description of FIG. 1 to FIG. 3 can be read on FIG. 4 as well. Only the differences are explained. Whereas the protrusions 10 in FIG. 3 have an abrupt, i.e. steep side 15 opposite to the side that continuously evolves from the inclined moving gap 20, the protrusions 10 in FIG. 4 have an overlap portion 16, overlapping with the rear facing side 14 of the neighbored plank 100 to thereby avoid a low pressure zone in the region close to the steep sides 15 (FIG. 3). This low pressure zone might cause the cooling gas to follow as well the upwardly directed steep side 15, what might be considered as disadvantage, as the initial flow of the cooling gas should be predominantly horizontal. A further advantage of the overlap portions 16 is that clinker particle drop into the moving gap is further reduced.
(19) The overlap portion 16 has a lower surface (down facing surface 17) that is preferably continuously curved from the moving gap's inclination towards the horizontal. The up facing side 18 is gently sloped like the whole rear facing side 14. In other words, the thickness of the overlap portion is preferably continuously reduced until the lower surface 17 and the up facing side 18 meet preferably in an edge 19 or edge like rounding. The edge 19 connects the lower edge of a front facing side 12 of a rearward protrusion with the front facing side 13 of the overlap portion 16.
(20) FIG. 5 is a top view on a section of an example conveyor floor 1. The planks may have the form as shown in FIG. 3 or FIG. 4, for example. The conveyor floor surface thus has planks 100 with crests 11 intersecting gently sloped rear facing sides 14 of protrusions. FIG. 5 shows four planks 100 with moving gaps 20 in between. The grate floor as shown in FIG. 5 has only two groups of planks 100, namely planks A and planks C. The planks A are suspended and driven to reciprocate as indicated by double headed arrow 3. All planks of group A reciprocate simultaneously forth and back. In other words, the planks of group A oscillate with a common frequency, phase and waveform. At least some of the planks of the group A can thus be coupled by at least one cross beam and may have a common suspension and preferably a common actuator. The planks of group C in contrast are static. In other words they do not reciprocate (relative to the base, which defines the reference system). Extended over the whole grate floor the depicted pattern of planks thus reads . . . A,C,A,C . . . , wherein the comma represents moving gaps. The connection to the conveyor floor side boundary is preferably by planks of group C. In this case the pattern reads |C, A,C, A, . . . A,C| wherein the vertical lines | symbolize the conveyor floor boundary.
(21) FIG. 6 is a top view on a section of a further conveyor floor 1. The section shows 4 planks 100 with moving gaps 20 in between. The grate floor as shown in FIG. 6 has only three groups of planks, namely planks A, planks B and planks C. The planks A and planks B are suspended and driven to reciprocate as indicated by double headed arrows 3. The planks may have a shape as explained for example with respect to FIG. 4 or 5. At least some of the planks of the group A can thus be coupled by at least one cross beam and may have a common suspension and preferably a common actuator. At least some of the planks of group B are preferably coupled accordingly, i.e. by at least one cross beam, and share a common suspension and preferably a common actuator.
(22) Conveying is obtained by the conveyor floor of FIG. 6 as follows: All planks of group A reciprocate simultaneously forth and back. In other words, they oscillate with common frequency A, phase A and waveform A. The planks of group B reciprocate as well simultaneously forth and back and thus oscillate with common frequency B, phase B and waveform B. The frequency A is preferably at least similar to the frequency B (more preferably identical). Both groups of planks advance forward preferably simultaneously but are retracted one group after the other, as indicated in the diagram below the section of the conveyor floor. Starting at to both groups of planks A and B simultaneously move in the conveying direction with a first positive speed v.sub.f until they reach their respective forward positions x.sub.f. The forward speeds are not necessarily identical, but may be identical. At t=t.sub.A, both groups of planks reach their maximum forward position x.sub.f and stop (v=0). The planks of group A are immediately retracted whereas the planks of group B remain in their forward position x.sub.f until the planks of group A are fully retracted, i.e. until they reach the position indicated as x.sub.b. The maximum of the absolute value of retraction speed v.sub.b is preferably higher than the maximum of the absolute value of the forward speed v.sub.f. In the example of FIG. 6 the absolute value of the forward speed v.sub.f is twice the retracting speed v.sub.b to thereby enhance conveying. When the planks of group A reach their retracted position x.sub.r the planks of group B are retracted as well with a retraction speed v.sub.r until they reach as well their respective retracted position x.sub.r. The retracted positions of the planks of groups A and B are not necessarily the same. As well, the retraction speeds may differ. Retraction of the planks of group B ends when they reach their retracted position x.sub.r and at t.sub.1 then the cycle restarts again.
(23) The planks of group C however are static. In other words they do not reciprocate (relative to the base, defining the reference system). Extended over the whole grate floor the depicted pattern of planks thus reads . . . , A,C,B,C,A,C,B, . . . , wherein the comma represents moving gaps. The connection to the conveyor floor side boundary is preferably by planks of group C. In this case the pattern reads |C, A,C,B, . . . A,C| or |C,A,C,B, . . . B,C|, wherein the vertical lines | symbolizes the conveyor floor boundary.
(24) FIG. 7 is a top view on a section of a further conveyor floor 1. The section shows 4 planks 100 with moving gaps 20 in between. The grate floor as shown in FIG. 7 has as well three groups of planks, namely planks A, planks B and planks C. The planks A and planks B are suspended and driven to reciprocate as indicated by double headed arrows 3. The planks of group C are static as already explained. For conveying bulk material, like e.g. clinker, one may drive and suspend the planks of the groups A and B as explained with respect to FIG. 6. Extended over the whole grate floor the depicted pattern of planks may read . . . A,B,C,A . . . , wherein the comma represents moving gaps. The connection to the conveyor floor side boundary is preferably by planks of group C. In this case the pattern reads |C, A,B,C,A, . . . B,C| or |C,B,A,C, . . . A,C|, wherein the vertical line | symbolizes the conveyor floor boundary.
(25) It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide a conveyor floor in particular for cooling bulk material like cement clinker or the like. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
(26) In FIG. 1 a conveyor floor 1 is sketched. The conveyor floor 1 is a grate floor e.g. for cooling and conveying clinker, which can be loaded from a rotary kiln via a clinker distribution system 5 onto the grate floor. The clinker is conveyed from a clinker inlet, i.e. the clinker distribution system 5 in a conveying direction being symbolized by an arrow 2 to a clinker outlet.
(27) The conveyor floor 1 has planks 100 extending in the longitudinal direction (indicated by double headed arrow 3) from the conveyor inlet to the conveyor outlet. The planks 100 are arranged in parallel one besides the other with moving gaps 20 in between. The moving gaps 20 (cf. FIG. 3 and FIG. 4) permit a reciprocating movement of the grate bars 101 of a plank 100 relative to the grate bars 101 of neighbored planks 100 along the longitudinal direction 2 of the grate floor as indicated by double headed arrows 3. In addition a cooling gas may be injected through the moving gaps 20 into a clinker bed being conveyed. Alternatively the same conveyor floor could be used as well for other bulk material, e.g. for corn that can be dried while conveyed by injecting air at a low relative humidity via the moving gaps into a corn layer being deposited on the conveyor floor.
(28) Grate boundaries 30, as well referred to as side walls 30, may be installed to the left and to the right of the planks (FIG. 1). The grate boundaries are preferably clad by some refractory material. The planks 100 next to the side walls 30 are preferably fixed relative to the respective side wall 30. In other words the planks next to the side wall 30 preferably do not reciprocate.
(29) The planks 100 are denominated A, B, C, indicating a group they belong to. The planks 100 of each group A, B, C are mounted to separate cross beams 40. The cross beams 40 carrying the planks of groups A and B are suspended and driven to reciprocate as indicated by the arrow 3. The cross beams 40 supporting the planks of group C are fixed, i.e. they are rigidly mounted to a base, e.g. by some static support structure. The pattern A,B,C as depicted is only an example. Other patterns, or in other words other sequences of groups are as well possible, for example |C,A,C,A . . . C| or |C, B, C, A, C, B, . . . , C| to list only two.
(30) As shown in FIG. 2 to FIG. 4, the planks 100 may have protrusions 10 forming a shingled surface as apparent. The protrusions 10 may for example have an approximately triangular longitudinal section (FIG. 2) with steep front facing side 12 facing in the conveying direction, i.e. towards the clinker outlet, and a gently slopes rear facing side 14. In the depicted example the front facing side is orthogonal to the conveying direction 2, but other angles are possible as well, provided that the mean slope of the front facing side is steeper than the mean slope of the gently sloped rear facing side 14. When moving the plank 100 in the conveying direction, the front facing side 12 acts like a block. Accordingly the grains of the bulk material are pushed forward by the forward movement of the plank. When retracting the plank, the grains of the bulk material slide over the ramp being formed by the rear facing side 14. Thereby, in a macroscopic view the coefficient of friction C.sub.f for a forward movement of a bulk material, like cement clinker, relative to the plank is smaller as the coefficient of friction C.sub.b for a backward movement of the same bulk material relative to said plank. The height h of the crest 11 and the length l.sub.r of the ramp have been optimized by extensive experiments with clinker. Astonishingly it turned out, that an optimized ratio of C.sub.b/C.sub.f can be realized with comparatively low crest 11 height h of only 3/10 of the typical grain diameter d.sub.g1 cm (possible 0.1 d.sub.ghd.sub.g, preferably 0.1 d.sub.gh0.5 d.sub.g). The optimum ramp l.sub.r length was found to be about 3 to 4 times the typical grain diameter d.sub.g (possible 1.5 d.sub.gl.sub.r7 d.sub.g, preferably 2.5 d.sub.gl.sub.r=5 d.sub.g). The median of the grain diameters can be considered as typical grain diameter.
(31) In FIG. 3 three planks 100 of a conveyor floor are shown, for example of a grate floor as sketched in FIG. 1. On each plank 100 are protrusions 10, as well referred to as elevations 10. The protrusions 10 each have a crest 11 from their left to their right (referring to the conveying direction 2). The longitudinal sections (cf. FIG. 2) of the protrusions 10 resemble triangles (the dotted line is a guide to the eyes). Each protrusion 10 has a front facing side 12 and rear facing side 14, where front and rear refer as well to the conveying direction 2. The front facing sides 12 have a steeper slope (as example almost 90 to the longitudinal axis) as the rear facing side (for example about 20, possible 2 to 35, preferred between 2 and 10). The height of the protrusions is symbolized by h. When pushing the planks A and/or B forward, the front facing sides 12 of the protrusions 10 work like a block being pushed forward, i.e. the clinker grains are as well moved in the forward direction. To this end, the height h of the protrusions 10, is preferably about 0.3 times the mean diameter of the clinker particles. When retracting preferably group A (or B) after group B (or A), the front sides 12 of the groups of planks B, C (or A, C) that are not retracted, block the clinker bed from following the retracted plank A. Instead, the clinker so to speak climbs up the gently sloped rear facing side 14 of the protrusion on plank A (or B).
(32) For a homogeneous aeration of the clinker, the moving gaps 20 are inclined against the vertical. For forming the inclined moving gap 20 each plank has a first narrow side with an inclined upper surface 21 and a second narrow side 22 with a complementary undercut. The upper surface 21 and the second narrow side are preferably parallel. Preferably, the protrusion 10 extends smoothly from the first narrow side as shown in FIG. 3 and FIG. 4. The transition from the first narrow side 21 to the gently sloped rear sides 14 of the protrusions 10 is preferably continuously curved, to thereby better attach the coolant to the rear side 14 of the protrusion 10. To even better attach the coolant to the rear side 14 of the protrusion 10 the protrusion 10 may have an overlapping portion 16, overlapping the gently sloped rear facing side 14 of the neighbored protrusion as shown in FIG. 4.
(33) As shown in FIG. 4, the protrusion 10 has a curved surface 17 continuing the inclined moving gap 20 to thereby improve attachment of the cooling gas flow to the surface 14 of the neighbored plank 100. A homogeneous aeration of the clinker bed is thereby further enhanced as well as transportation of clinker dust particles to the upper region of the clinker bed. In the cross section, the protrusion 10 is preferably continuously curved to thereby provide an accordingly curved moving gap 20.
(34) The grate floor in FIG. 4 is similar to the grate floor as shown in FIG. 2 and FIG. 3, the description of FIG. 1 to FIG. 3 can be read on FIG. 4 as well. Only the differences are explained. Whereas the protrusions 10 in FIG. 3 have an abrupt, i.e. steep side 15 opposite to the side that continuously evolves from the inclined moving gap 20, the protrusions 10 in FIG. 4 have an overlap portion 16, overlapping with the rear facing side 14 of the neighbored plank 100 to thereby avoid a low pressure zone in the region close to the steep sides 15 (FIG. 3). This low pressure zone might cause the cooling gas to follow as well the upwardly directed steep side 15, what might be considered as disadvantage, as the initial flow of the cooling gas should be predominantly horizontal. A further advantage of the overlap portions 16 is that clinker particle drop into the moving gap is further reduced.
(35) The overlap portion 16 has a lower surface (down facing surface 17) that is preferably continuously curved from the moving gap's inclination towards the horizontal. The up facing side 18 is gently sloped like the whole rear facing side 14. In other words, the thickness of the overlap portion is preferably continuously reduced until the lower surface 17 and the up facing side 18 meet preferably in an edge 19 or edge like rounding. The edge 19 connects the lower edge of a front facing side 12 of a rearward protrusion with the front facing side 13 of the overlap portion 16.
(36) FIG. 5 is a top view on a section of an example conveyor floor 1. The planks may have the form as shown in FIG. 3 or FIG. 4, for example. The conveyor floor surface thus has planks 100 with crests 11 intersecting gently sloped rear facing sides 14 of protrusions. FIG. 5 shows four planks 100 with moving gaps 20 in between. The grate floor as shown in FIG. 5 has only two groups of planks 100, namely planks A and planks C. The planks A are suspended and driven to reciprocate as indicated by double headed arrow 3. All planks of group A reciprocate simultaneously forth and back. In other words, the planks of group A oscillate with a common frequency, phase and waveform. At least some of the planks of the group A can thus be coupled by at least one cross beam and may have a common suspension and preferably a common actuator. The planks of group C in contrast are static. In other words they do not reciprocate (relative to the base, which defines the reference system). Extended over the whole grate floor the depicted pattern of planks thus reads . . . A,C,A,C . . . , wherein the comma represents moving gaps. The connection to the conveyor floor side boundary is preferably by planks of group C. In this case the pattern reads |C, A,C, A, . . . A,C| wherein the vertical lines | symbolize the conveyor floor boundary.
(37) FIG. 6 is a top view on a section of a further conveyor floor 1. The section shows 4 planks 100 with moving gaps 20 in between. The grate floor as shown in FIG. 6 has only three groups of planks, namely planks A, planks B and planks C. The planks A and planks B are suspended and driven to reciprocate as indicated by double headed arrows 3. The planks may have a shape as explained for example with respect to FIG. 4 or 5. At least some of the planks of the group A can thus be coupled by at least one cross beam and may have a common suspension and preferably a common actuator. At least some of the planks of group B are preferably coupled accordingly, i.e. by at least one cross beam, and share a common suspension and preferably a common actuator.
(38) Conveying is obtained by the conveyor floor of FIG. 6 as follows: All planks of group A reciprocate simultaneously forth and back. In other words, they oscillate with common frequency A, phase A and waveform A. The planks of group B reciprocate as well simultaneously forth and back and thus oscillate with common frequency B, phase B and waveform B. The frequency A is preferably at least similar to the frequency B (more preferably identical). Both groups of planks advance forward preferably simultaneously but are retracted one group after the other, as indicated in the diagram below the section of the conveyor floor. Starting at t.sub.0 both groups of planks A and B simultaneously move in the conveying direction with a first positive speed v.sub.f until they reach their respective forward positions x.sub.f. The forward speeds are not necessarily identical, but may be identical. At t=t.sub.A, both groups of planks reach their maximum forward position x.sub.f and stop (v=0). The planks of group A are immediately retracted whereas the planks of group B remain in their forward position x.sub.f until the planks of group A are fully retracted, i.e. until they reach the position indicated as x.sub.b. The maximum of the absolute value of retraction speed v.sub.b is preferably higher than the maximum of the absolute value of the forward speed v.sub.f. In the example of FIG. 6 the absolute value of the forward speed v.sub.f is twice the retracting speed v.sub.b to thereby enhance conveying. When the planks of group A reach their retracted position x.sub.r the planks of group B are retracted as well with a retraction speed v.sub.r until they reach as well their respective retracted position x.sub.r. The retracted positions of the planks of groups A and B are not necessarily the same. As well, the retraction speeds may differ. Retraction of the planks of group B ends when they reach their retracted position x.sub.r and at t.sub.1 they the cycle restarts again.
(39) The planks of group C however are static. In other words they do not reciprocate (relative to the base, defining the reference system). Extended over the whole grate floor the depicted pattern of planks thus reads . . . , A,C,B,C,A,C,B, . . . , wherein the comma represents moving gaps. The connection to the conveyor floor side boundary is preferably by planks of group C. In this case the pattern reads |C, A,C,B, . . . A,C| or |C,A,C,B, . . . B,C|, wherein the vertical lines | symbolizes the conveyor floor boundary.
(40) FIG. 7 is a top view on a section of a further conveyor floor 1. The section shows 4 planks 100 with moving gaps 20 in between. The grate floor as shown in FIG. 7 has as well three groups of planks, namely planks A, planks B and planks C. The planks A and planks B are suspended and driven to reciprocate as indicated by double headed arrows 3. The planks of group C are static as already explained. For conveying bulk material, like e.g. clinker, one may drive and suspend the planks of the groups A and B as explained with respect to FIG. 6. Extended over the whole grate floor the depicted pattern of planks may read . . . A,B,C,A . . . , wherein the comma represents moving gaps. The connection to the conveyor floor side boundary is preferably by planks of group C. In this case the pattern reads |C, A,B,C,A, . . . B,C| or |C,B,A,C, . . . A,C|, wherein the vertical line | symbolizes the conveyor floor boundary.
LIST OF REFERENCE NUMERALS
(41) 1 clinker cooler 2 conveying direction 3 reciprocating movement 5 clinker inlet distribution system 10 elevation/protrusion 11 crest, from left to right 12 front facing side of protrusion 10 13 front facing side of overlap portion 16 14 rear facing side of the protrusion 10 15 steep side of protrusions 10 16 overlap portion of the protrusion 17 lower side of overlap portion 18 rear facing side of overlap portion 19 side edge of overlap portion. 20 moving gap, slit, slot 21 lower boundary of moving gap 22 upper boundary of moving gap 30 side wall/boundary 40 cross beam 100 plank A, B, C planks of groups A, B, C, respectively h height of protrusion 10 l.sub.r length of ramp/length of rear facing side of protrusion 10
