Vertical ring shaft kiln

Abstract

Invention relates to a vertical ring shaft kiln comprising a vertical burning region (1); an intermediate sintering zone (Z.sub.3) surrounded by a first wall (10) and an opposite second wall (20) at the burning region (1) to obtain a clinker from a particulate raw material flowing downwards direction.

Claims

1. A vertical ring shaft kiln comprising: a vertical burning region having an intermediate sintering zone defined by a first wall and a second wall, the second wall being opposite the first wall, and defining a gap therebetween, the first wall and second wall being of a ring shape one inside the other; a support wall connecting a bottom part of the first wall and a bottom part of the second wall with an outlet; a plurality of nozzles having outer nozzles at the first wall and inner nozzles at the second wall, said plurality of nozzle adapted to develop a flame in an adjustable manner throughout a length of the gap by injecting a fuel and a gas inside the sintering zone, wherein said plurality of nozzles comprise outer and inner auxiliary nozzles positioned at a distance from the inner and outer nozzles, the outer and inner auxiliary nozzles adapted to inject oxygen or air inside the sintering zone; a plurality of heat sensors disposed at an outer side of the first wall so as actual heat exchange information at the first wall; a detection unit cooperative with said plurality of heat sensors so as to produce a thermal map of the sintering zone and adapted to fine over-burned or unburned spots by comparing a detected heat value with a homogenous heat pattern set by a threshold heat value; a control unit connected to said detection unit so as to prevent the over-burned or unburned spots by changing a vertical flow speed or by activing an adjacent nozzle or auxiliary nozzle of the plurality of nozzles; and a roller crusher positioned at the outlet of said vertical burning region, said roller crusher being fed by sintering material so as to determine the vertical flow speed.

2. The vertical ring shaft kiln of claim 1, wherein the first wall and the second wall are parallel to each other throughout a drying, calcining, sintering, clinkerizing, and gasification zone of said vertical burning region.

3. The vertical ring shaft kiln of claim 1, wherein the length, of the gap between the first wall and the second wall is between two meters and six meters.

4. A method for producing clinker using the vertical ring shaft kiln of claim 1, the method comprising: providing the vertical ring shaft kiln of claim 1; feeding raw material from an upper side of said vertical burning region homogenously distributed into the sintering zone at a sintering temperature to obtain a clinker from the raw material downwardly at a predetermined flow speed, wherein the sintering zone is arranged such that a heat distribution pattern inside the sintering zone homogenously transforms all of the raw material into a clinker form, wherein the heating of the raw material from ambient temperature up to 1800° C. is performed with the plurality of burners provided in the sintering zone.

5. The method of claim 4, further comprising: controllably releasing the clinker from the sintering zone at the vertical flow speed.

Description

(1) FIG. 1 is a cross-sectional front view of a vertical ring shaft kiln according to an embodiment of the invention.

(2) FIG. 2 is a cross-sectional front view of another vertical ring shaft kiln having a number of heat sensor array.

(3) FIG. 3 is a cross-sectional top view of a ring shaped burning region according to an exemplary embodiment of the present invention with outer flame development on one of the nozzles.

(4) FIG. 4 is a cross-sectional top view of a ring shaped burning region according to FIG. 3 with inner flame development on one of the nozzles

(5) FIG. 5 is a cross-sectional top view of a hexagonal burning region according to another embodiment of the invention.

(6) FIG. 6 is a cross-sectional top view of a square burning region according to another embodiment of the invention.

REFERENCE NUMERALS

(7) 1 Burning region 2 Inlet 10 First wall 11 Inner side 12 Top part 13 Outer side 14 Bottom part 15 Heat sensor 20 Second wall 21 Inner side 22 Top part 23 Outer side 24 Bottom part 30 Support wall 32 Outlet 34 Roller crusher 50 Outer flame 52 Peak section 53 Outer periphery 60 Burners 62 Outer nozzle 621 Oxygen/air outlet 622 Fuel outlet 63 Outer auxiliary nozzle 64 Inner nozzle 65 Inner auxiliary nozzle 70 Inner flame 72 Peak section 73 Outer periphery 90 Control unit 92 Detection unit Z.sub.1 Preheating zone Z.sub.2 Calcination zone Z.sub.3 Sintering zone Z.sub.4 Cooling zone v.sub.f Flow speed L Length t.sub.s Sintering temperature t.sub.d Detected heat value t.sub.f Treshold heat value R1 Outer radius R2 Inner radius Dm Average diameter

DETAILED DESCRIPTION OF THE INVENTION

(8) In this detailed description, the subject matter improvement is explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

(9) With reference to the drawings, a vertical ring shaft kiln is partially shown from the front. The burning region (1) is defining a space for clinker in pellet form for flowing in downwards direction. In the vertical ring shaft kiln the burning region (1) gradually increases the temperature of the flowing material. The raw cement material is fed from an inlet (2) at the upper side of the burning region (1). The inlet (2) is stationary but can be in a rotatable form. The bulk granulated, e.g. pellet material inside the burning region (1) follow a linear path to the bottom end of the burning region (1). An imaginary horizontal line divide the burning region (1) into four zones based on the chemical reaction due to the heat increase. The first zone facing towards the inlet (2) is a preheating zone (Z.sub.1), i.e. drying zone wherein the granulated raw cement material is heated from the room temperature by the hot gasses elevating from the three subsequent bottom sections of the burning region (1). Preheated clinker enters into a space confined by an opposing second wall (20) to the first wall (10). The second wall (20) is substantially parallel to the first wall (10). The raw material between the space of an inner side (11) of the first wall (10) and the facing inner wall (21) of the second wall (20) has a predetermined flow speed (v.sub.f) to the downwards direction. The vertical flow speed (vf) is determined by a roller crusher (34) being fed by the sintered material. The raw cement material's heat increases to a calcination temperature inside a calcination zone (Z.sub.2) following to the preheating zone (Z.sub.1). Calcination of the cement raw material is completed inside the calcination zone (Z.sub.2) wherein the temperature is up to 600-1200° C. Subsequent to the calcination the cement raw material continuously flow downwards direction by its own weight to a third zone wherein the temperature of the cement raw material is at the maximum level between 1200-1450° C. so called a sintering zone (Z.sub.3). A length (L) between the inner sides (11, 21) of two corresponding parallel first and second wall (10, 20) is defined as 3 meters. The heat distribution pattern is determined by flow speed (v.sub.f) of the material in the vertical direction. The sintering zone (Z.sub.3) is followed by a clinkerizing and gasification zone which are also combined with the sintering zone (Z.sub.3) in the figures.

(10) In order to ensure great burning efficiency, the cement raw material is bonded with a fuel, such as coal in pellet form. Therefore, the fuel bonded with the granulated cement raw material burns during sintering process due to the high temperature inside the sintering zone (Z.sub.3). The first wall (10) and the second wall (20) is made of refractory materials. A top part (11) of the first wall (10) is higher than a top part (22) of the second wall (20). Therefore, the cement raw material overflow over the top side (22) of the second wall (20) to transfer another section or create a buffer to feed the preheating zone (Z.sub.1). The bottom of the sintering zone (Z.sub.3) is followed by a cooling zone (Z.sub.4) where the clinker starts cooling down. The cooling zone (Z.sub.3) is having a bottom closed by a support wall (30) in a funnel shape. The support wall (30) connect a bottom part (14) of the first wall (10) and an opposite bottom part (24) of the second wall (20). At the lower center of the support wall (30) the outlet (32) is arranged. The outlet (32) feed the roller crusher (34) for the clinker. The outlet (32) is controllably release the clinker and define the vertical flow speed (v.sub.f). Outer side (13) of the first wall (10) is defining outer part of the overall burning region (1). A number of heat sensors (15) are disposed at the outer wall of the calcination zone (Z.sub.2) and sintering zone (Z.sub.3) in a vertical direction. Each one of the heat sensors (15) provide actual heat change information at the first wall (10). Inner wall of the first wall (10) has a distance with the center of the vertical kiln which define an outer diameter (R1). An inner side (21) of the second wall (20) has an inner radius (R2) with the center. The length (L) is equal to the difference between the outer radius (R1) and the inner radius (R2). In case of an observation on the unburned spots in the vertical direction, the cement raw material is heated up by the burners as shown in FIG. 2.

(11) In FIG. 2, a partial cross-sectional top view of an exemplary embodiment of the subject matter sintering zone (Z.sub.3) of the vertical ring shaft kiln is shown. An array of multiple spaced apart burners (60) are arranged at the inner side (11, 21) of the corresponding first and the second wall (10, 20). The first wall (10) and the second wall (20) is a ring shaped one inside the other. The first wall (10) forms an outer hollow body in which the second wall (20) is providing an inner hollow body at a distance of the length (L) between the facing parallel sides of the first and the second wall (10, 20). Inner side (11) of the first wall (10) comprises a number of burners (60) forming an outer nozzle (62) aligned radially inwardly inside the sintering zone (Z.sub.3). Similarly, an inner nozzle (64) provided at the inner side (21) of the second wall (20) is extending outwardly to the inner wall (11) of the first wall (10). Each one of the inner nozzles (62) and the outer nozzles (64) having a number of auxiliary nozzles (63, 65) at a distance from the corresponding inner and outer nozzle (62, 64).

(12) Each one of the outer nozzles (62) and outer auxiliary nozzle (63) arranged so that bottom of an outer flame (50) provided by the outer nozzle (62) and outer auxiliary nozzle (64) can be developed adjacent to each other. Similarly, the inner nozzle (64) and inner auxiliary nozzle (65) has a similar configuration such that each one of the inner nozzle (64) and neighboring inner auxiliary nozzle (65) develop an inner flame (70) having ends adjacent to each other. Inner and outer flames (50, 70) are having hot zone closer to the corresponding burners (60) and less effective heated zone at the outer periphery (53, 73) of the flames. Therefore, opposing outer nozzle (62) and inner nozzle (64) spaced apart in horizontal direction so that the peak section (52, 72) of the corresponding flame does not intersect otherwise over burned clinker formation may occur. Inner nozzle (64) and outer nozzle (62) is operated independent from each other.

(13) A detection unit (92), e.g. a thermal camera is producing a thermal map of the sintering zone (Z.sub.3) to find over burned or unburned spots comparing a detected heat value (t.sub.d) with the homogenous heat pattern previously set by a threshold heat value (t.sub.t) between 1000°−1500° C. In case of a difference between the threshold heat value (t.sub.t) and the detected heat value (t.sub.d) a control unit (90) in connection with the detection unit (92) manually or automatically, change the vertical flow speed (v.sub.f) or activate the neighboring corresponding outer or inner nozzle (62, 64) to provide a homogenous heating pattern at the unburned or over burned spot. Inner nozzle (64) is injecting oxygen/air and the outer nozzle (62) inject a fuel, such as natural gas inside the burning region (1).

(14) In FIG. 3, a cross-sectional view of another embodiment of the invention from the top is shown. The burning region (1) is formed between the ring formed first wall (10) and second wall (20). The length (L) between the first and second walls (10, 20) is arranged so that the distance value of the length (L) is smaller than the sum of the radius of the outer flame (50) and the inner flame (70). Therefore, either one of the corresponding outer flame (50) or inner flame (70) may reach any one of the unburned spots distributed across burning region (1) to transform the cement raw material to the clinker in transverse direction. A burner (60) has an outer nozzle (62) is divided into two injectors namely an oxygen/air outlet (621) and a fuel outlet (622). Depending on the heat distribution pattern inside the sintering zone (Z.sub.3) only oxygen/air injection to the less heated or so called unburned zone can be sufficient to heat up the region and remove the unburned spot from the heat distribution pattern. Otherwise only fuel, such as natural gas or combination of fuel and oxgen can be selectively injected to increase the heat for a fast and higher level of correction of the cook unburned spot and sintered material.

(15) The outer flame (50) developing from inner side of the first wall (10) across the second wall (20) is having a peak section (52) exceeding the average diameter (Dm) through the sintering zone (Z3). An outer periphery (53) of the outer flame (50) reach to the unburned spot particularly closer to the first wall (10) and heat up the unburned spot to obtain the clinker.

(16) In FIG. 4, the same configuration of the burning region (1) is shown with the inner flame (70) development inside the sintering zone (Z3). The inner flame (70) having a peak section (72) which is close to the average diameter (Dm) inside the sintering zone (Z3). The outer periphery (73) of the inner flame (70) reach any unburned spot closer to the second wall (20) of the sintering zone (Z3).

(17) FIG. 5 shows another embodiment of the invention where no burners (60) are provided. The shape of the first wall (10) and the second wall (20) is hexagonal arranged that the walls of the hexagon shape is parallel and equal to the length (L) across the sintering zone (Z.sub.3). FIG. 6 simply shows a square configured vertical shaft kiln according to the invention. Other polygonal shapes, funnel shapes or other geometrical designs of the burning region (1) is obvious as long as the sintering zone (Z.sub.3) is having parallel walls distant with the equal length (L).

(18) In order to change the sintering capacity of the vertical kiln, the average diameter (Dm) of the sintering zone (Z.sub.3) is simply expanded while keeping the distance, i.e. length (L) between the first wall (10) and the opposing second wall (20), at the same value.