Granular solid cooling line

Abstract

A line (1) for cooling hot granular solids having a temperature above 1000°C, the cooling line (1) being in particular a first cooler (2) provided with at least one grate (4) intended to receive the particulate solid; a second cooler (3) arranged downstream of the first cooler (2) in the direction of movement of the particulate solids, the second cooler (3) being rotatable and comprising a material inlet (9) through which the particulate solids enter and a material outlet (10) through which the particulate solids exit, The cooling line (1) is configured so that the particulate solid moves continuously from a first cooler (2) to a second cooler (3), line (1).

Description

[Technical Field]

[0001] The present invention relates to a cooling line and a cooling method implementing the same. More briefly, the present invention relates to a cooling line for granular solids having a temperature above 1000° C. In particular, the present invention relates to the cement production industry, where the granular solid is clinker intended for cement production. [Background technology]

[0002] Cooling lines are an essential part of cement production.

[0003] Clinker is a component of cement produced from a mixture of limestone and aluminosilicates.

[0004] Clinkering is the step in which the limestone and aluminosilicate mixture is turned into clinker. Depending on the production site and the surrounding geology, this step is carried out at temperatures of around 1500°C.

[0005] Clinkering is carried out in rotary kilns. Once the clinker is obtained, it must be cooled. This cooling is carried out in cooling lines.

[0006] For example, there are cooling lines equipped with grate coolers.

[0007] These cooling lines are particularly energy intensive from an electrical point of view due to the use of ventilation systems that blow through grates with high pressure losses.

[0008] In the context of reducing the environmental impact of a clinker production plant, the cooling line is a potential energy saving item.

[0009] The present invention aims to reduce the energy consumption of the cooling lines in order to improve the overall energy efficiency of the clinker production facility. Summary of the Invention

[0010] For this purpose, a cooling line for hot granular solids with temperatures exceeding 1000°C, a first device for generating a first cooling air flow, a first cooler equipped with at least one grid intended to receive the particulate solid, said grid being capable of being traversed by a first cooling air flow; a second cooler arranged downstream of the first cooler in the direction of movement of the particulate solids, the second cooler being rotatable and having a material inlet through which the particulate solids enter and a material outlet through which the particulate solids exit, the second cooler having a second cooling air flow circulating therethrough; a cooling line configured to move particulate solids continuously from a first cooler to said second cooler, said cooling line comprising an air extraction circuit including an air extraction device, said air extraction circuit being capable of partially generating said second cooling air stream; A cooling line is first proposed, in which an air extraction device is able to extract a first fraction of the second cooling air flow.

[0011] The cooling lines ensure sufficient cooling efficiency, they also optimize the consumption of electrical energy required for their operation and make it possible to recover at least a portion of the thermal energy present in the clinker.

[0012] Various additional features may be provided singly or in combination. the cooling line is arranged so that the second non-extracted fraction of the second air stream mixes with the first air stream in the first cooler to obtain a mixture; the cooling line comprises means for recovering the mixture; the air extraction device is configured to extract air from inside the second cooler; the air extraction device comprises an extraction end arranged inside the second cooler; - the second cooler extends in an extension direction substantially parallel to the direction of movement of the particulate solid, said second cooler extending over a length L measured in the extension direction, said extraction end being disposed within the second cooler at a distance D measured in the extension direction from the material outlet and said extraction end of at least 0.5L; - distance D is 0.7L to 0.95L, the extraction device comprises an extraction line arranged inside the second cooler, the extraction line extending substantially parallel to the second cooler; the extraction line and the second cooler are substantially concentric; at least one grid of the first cooler is fixed; the first cooler comprises at least one crusher for crushing the particulate solid; The first cooler comprises a first part and a second part separated from each other by a grinder, and at least one fixed grate in each part is inclined so that the granular solid moves under the influence of the Earth's gravity.

[0013] Secondly, a method for cooling a particulate solid by means of a cooling line as described above is proposed, said method comprising the following operations: - circulation of at least a first air flow in the first cooler through at least one fixed grate, - circulation of a second air flow in the second cooler, which is partly generated by an air extraction circuit connected to the material outlet, - Extracting a first fraction of the second air flow in a second cooler.

[0014] Various additional features may be provided singly or in combination. the extraction step is carried out to leave only a second fraction of the second air stream in the second cooler; - directing a second fraction of the second air stream towards the first air stream to mix therewith, said mixture being recovered for subsequent use by means for recovering said mixture; the first air flow contributes to a proportion of the mixture of 50% to 60% and the second air flow contributes to a proportion of the mixture of 40 to 50%; the first air stream contributes to a proportion of the mixture of about 55% and the second air stream contributes to a proportion of the mixture of about 45%; The first fraction extracted from the second air flow is 65-80% of the second air flow. [Brief explanation of the drawings]

[0015] Further features and advantages of the present invention will become apparent from a reading of the following detailed description, for the understanding of which reference should be made to the accompanying drawings. [Figure 1] 1 is a schematic diagram of a cooling line according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0016] A cooling line 1 according to the invention is shown in FIG.

[0017] The cooling line 1 comprises a first cooler 2 and a second cooler 3 .

[0018] The first cooler 2 comprises several grates 4. These grates 4 are suitable for receiving a particulate solid, in this case clinker that has been heated to a temperature of more than 1000°C in a kiln 5 adjacent to the first cooler 2.

[0019] As shown in Figure 1, the grate 4 is inclined in the direction of movement of the clinker, which is represented by the movement arrow 6. This inclination allows the clinker to move within the first cooler 2 under the influence of gravity and its substantially spherical geometry.

[0020] The cooling line 1 comprises at least a first device 7 for generating a first cooling air flow 8. The first device 7 for generating the first air flow 8 is arranged so that the first cooling air flow 8 passes through a grate 4. The first air flow 8 can therefore pass through the grate 4. The grate 4 takes the form of a perforated metal plate, the perforations of which are smaller than the clinker so that the clinker cannot pass through the perforations.

[0021] The second cooler 3 is of the rotary type and is arranged downstream of the first cooler 2 in the direction of movement of the clinker. The second cooler 3 comprises a material inlet 9, adjacent to the first cooler 2, through which the clinker leaving the first cooler 2 enters. The second cooler 3 comprises a material outlet 10 through which the clinker exits.

[0022] The cooling line 1 advantageously comprises an air extraction circuit 19 capable of partially generating the second cooling air flow 12. For this purpose, the air extraction circuit 19 comprises: an air extraction device 17 capable of extracting a fraction of the second cooling air flow 12; - an extraction fan 23.

[0023] 1, the air extraction circuit 19 further comprises an extraction line 20, a heat exchanger 21, and a filter 22. The extraction line 20 is in fluid communication with the heat exchanger 21. The heat exchanger 21 is in fluid communication with the filter 22. The filter 22 is in fluid communication with an extraction fan 23.

[0024] The heat exchanger 21 is an emergency heat exchanger to protect the filter 22 from possible overheating.

[0025] The extraction circuit 19 can therefore partly generate the second cooling air flow 12 by drawing air directly from the second cooler 3, in particular via the extraction fan 23. Part of the second cooling air flow 12 can then move in the second cooler 3 in the opposite direction to the movement of the clinker, i.e. against the flow of material circulating in the second cooler 3 from the material inlet 9 to the material outlet 10.

[0026] The second cooler 3 is arranged substantially horizontally as shown in Figure 1. The second rotary cooler 3 advantageously comprises lifters 13 arranged on the inner surface 14 of the rotary drum 15 of said second cooler 3. These lifters 13 have a profile that allows the clinker to be resuspended in the cooling air flow and improves heat exchange.

[0027] The cooling line 1 is therefore configured so that the clinker moves continuously from the first cooler 2 to the second cooler 3 .

[0028] The provision of a first grate cooler 2, followed by a second rotary cooler 3, with an extractor 17 extracting a first fraction 27 from the second cooling air stream 12, reduces power consumption while maintaining acceptable clinker cooling dynamics and a good recovery efficiency of the thermal energy contained in the clinker. The first grate cooler 2 is energy intensive from an electrical standpoint, since the first air stream 8 is forced at high pressure through the clinker bed dispersed on the grates 4. The first cooler 2 is therefore used to quench the clinker, rapidly bringing it to a temperature just below 1000°C. Cooling is then completed in the second rotary cooler 3, which is less energy intensive in terms of the power absorbed by the extractor 17 or any elements connected to this extractor 17. The extractor 17 extracts a first fraction 27 from the second air stream 12 and then the other fraction (hereafter second fraction 28) which is then mixed with the first air stream 8 in the first cooler 2, preferably to obtain a mixture having a flow rate and temperature suitable for use elsewhere in the clinker production process.

[0029] The cooling lines 1 described above, by their arrangement, allow for significant electrical energy savings and an increase in the overall efficiency of the cement plant.

[0030] Preferably, the cooling line 1 advantageously comprises at least one heating hood 16 in the form of a cavity. In particular, the heating hood 16 is located at the location where the grate 4 is located and where a mixture comprising the first air stream 8 and the second fraction 28 of the second air stream 12 is generated. In addition, the cooling line 1 preferably further comprises one or more mixture recovery lines 30 which can be arranged at different points in the line 1 above the first cooler 2 depending on the specific temperature requirements of the mixture to be recovered. In particular, they capture the mixture comprising the first air stream 8 and the second fraction 28 of the second air stream 12.

[0031] It should be noted that the second fraction 28 of the second air flow 12 is directed towards the first cooler 2 insofar as the first cooler 2 includes a negative pressure zone, for example, created by the furnace draft fan 5 and / or by the heating hood 16 and / or by the mixture recovery line 30 to which the mixture recovery element is typically connected.

[0032] According to one embodiment, the air extraction device 17 is configured to extract air from inside the second cooler 3. More specifically, the extraction device 17 comprises an extraction end 18. The extraction end 18 is arranged inside the second cooler 3. The extraction of air by the extraction end 18 arranged at this point advantageously makes it possible to reduce the amount of air in the second air stream 12 before mixing with the first air stream 8. Thus, the temperature of the mixture comprising the first air stream 8 and the second fraction 28 of the second air stream 12 is suitable for subsequent use in the cement production process.

[0033] The second cooler 3 extends in one direction (hereinafter referred to as the X-axis), which is horizontal.

[0034] According to one embodiment variant, the second cooler 3 takes the form of a tube rotatably mounted on a fixed support. The rotatably mounted tube has a slight inclination, for example a slope of a few degrees, to allow the clinker in the second cooler 3 to move from the material inlet 9 to the material outlet 10. The second cooler 3 has a distance L measured along the X-axis between the material inlet 9 and the material outlet 10.

[0035] According to one embodiment variant, the extraction end 18 is arranged in the second cooler 3 at a distance D measured along the X axis. The distance D is measured between the material outlet 10 of the second cooler 3 and the extraction end 18.

[0036] Advantageously, the distance D is greater than or equal to 0.5 L. By positioning the extraction end 18 at this distance D, the first fraction 27 of the second air stream 12 is extracted so that the second air stream 12 has time to cool the clinker in the second cooler 3.

[0037] In a preferred embodiment, the distance D is between 0.7 L and 0.95 L. Advantageously, this distance D allows the clinker to be cooled efficiently and ensures that the remaining second fraction 28, which is intended to be mixed with the first air stream 8 in the first cooler 2, is at the correct temperature.

[0038] In the embodiment shown in Figure 1, the extraction line 20 is arranged inside the second cooler 3. As can be seen, the extraction line 20 extends substantially parallel to the second cooler 3. This arrangement is advantageous in that it allows the extraction end 18 to be positioned inside the second cooler 3. In addition, this arrangement avoids complicating the architecture of the extraction circuit 19 by freeing it from the constraints inherent in the rotational movement of the rotating drum 15.

[0039] According to one embodiment, the extraction line 20 is in the form of a tube. The extraction line 20 and the second cooler 3 are substantially concentric, which further relieves them from the constraints inherent in the rotational movement of the rotating drum 15. For example, the first portion of the extraction line 20 and the rotating drum 15 are substantially concentric and rotate together, and the second portion of the extraction line 20 is fixed with respect to the rotational movement of the rotating drum 15 and is connected to the first portion of the extraction line 20 by a rotary joint system.

[0040] The first cooler 2 comprises two parts 24, 25, namely a first part 24 and a second part 25. The first part 24 and the second part 25 each comprise one or more fixed grates 4. As can be seen in Figure 1, the grates 4 are inclined so that the clinker moves under the influence of the Earth's gravity, as previously mentioned.

[0041] The use of a fixed grid 4 advantageously simplifies the operation of the cooling line 1 and improves its reliability despite high clinker temperatures.

[0042] The cooling line 1 advantageously comprises a crusher 26, which is arranged between the first section 24 and the second section 25. The crusher 26 can be used to reduce the size of the clinker particles, in particular the crust-forming elements. The crusher 26 is arranged after the first section 24 so that the clinker undergoes a temperature reduction in order to protect the crusher 26 and prevent it from being used at an excessively high temperature.

[0043] In the following, the operation of the cooling line 1 is described.

[0044] The clinker moves under the influence of gravity in the slightly inclined kiln 5. It then lands on the fixed grate 4 of the first part 24 of the first cooler 2. Under the influence of gravity, the clinker moves and is crushed in the crusher 26. On leaving the crusher 26, the clinker falls onto the fixed grate 4 of the second part 25 of the second cooler 3. The clinker moves under the influence of gravity into the second part 25 of the first cooler 2. The clinker then falls into the second cooler 3, where its temperature drop continues throughout its journey through the second cooler 3.

[0045] At least a first air stream 8 is generated by the first air generator 7. This first air stream 8 is sent through the fixed grates 4 in the first section 24 and the second section 25. The first air stream 8 is sent at high pressure so that it can pass through the clinker bed spread on each fixed grate 4. This action "quenches the clinker" so that its temperature drops quickly below 1000°C. The first air stream 8 increases in temperature upon contact with the hot clinker.

[0046] A second air flow 12 is generated by an air extraction circuit 19 and by a vacuum zone contained in the first cooler 2. This second air flow 12 is initiated in the second cooler 3 by a material outlet 10, as shown in the drawing.

[0047] In the second cooler 3, a first fraction 27 of the second air stream 12 is extracted. This extraction is carried out via an extraction device 17 included in the air extraction circuit 19. The first fraction 27 of the extracted air is sent to a heat exchanger 21. The first fraction 27 is then sent to a filter 22 to remove clinker dust and is then discharged into the atmosphere.

[0048] According to an embodiment not shown in the figures, the energy, in particular the thermal energy, of the first fraction 27 of the second air stream 12 is then recovered in a clinker or cement production process using known ad hoc equipment. For example, the energy from the first fraction 27 of the second air stream 12 can be used to dry raw materials or fuels required for the clinker production process.

[0049] A second fraction 28 of the second air stream 12, which is preferably not extracted, enters the first cooler 2 where it mixes with the first air stream 8. This mixture is then recovered in the heating hood 16 and may also be recovered via one or more of the recovery lines 30. This air mixture has temperature and flow characteristics that make it suitable for use as an oxidant to feed, for example, a kiln burner, a combustion chamber integrated into the clinker production line, or even a calciner, significantly increasing the energy efficiency of the clinker manufacturing process.

[0050] According to one embodiment, the first air stream 8 contributes to a proportion of the mixture between 50% and 60%. The second air fraction 28 contributes to a proportion of the mixture between 40 and 50%.

[0051] According to one embodiment, the first fraction 27 extracted from the second air flow 12 is between 65 and 80% of the second air flow 12 .

[0052] In a preferred embodiment, the first air stream 8 contributes to a proportion of the mixture of approximately 55%; a second fraction 28 contributes to a proportion of the mixture of about 45%; The first fraction 27 extracted from the second air flow 12 is approximately 73%.

[0053] In a preferred embodiment, for example: The first injected air flow 8 is 0.5 Nm 3 / kg clinker volume flow rate, The second injected air flow 12 is 1.5 Nm 3 / kg clinker volume flow rate, The first fraction 27 of the second air flow 12 is 1.1 Nm 3 / kg flow rate, -therefore, the second fraction 28 is 0.4 Nm 3 / kg clinker flow rate, As a result, the mixture of the first air flow 8 and the second air fraction 28 has a total air flow of 0.9 Nm 3 / kg.

Claims

1. A line (1) for cooling a hot granular solid having a temperature above 1000°C, the cooling line (1) comprising: a first device (7) for generating a first cooling air flow (8), a first cooler (2) equipped with at least one grid (4) intended to receive said particulate solids, said grid (4) being capable of being traversed by said first cooling air flow (8); a second cooler (3) arranged downstream of the first cooler (2) in the direction of movement of the particulate solid, the second cooler (3) being rotatable and having a material inlet (9) through which the particulate solid enters and a material outlet (10) through which the particulate solid exits, and through which a second cooling air flow (12) circulates; the cooling line (1) is configured so that the particulate solid moves continuously from the first cooler (2) to the second cooler (3), the cooling line (1) comprises an air extraction circuit (19) including an air extraction device (17), the air extraction circuit (19) being capable of partially generating the second cooling air flow (12); A line (1) from which the air extraction device (17) is capable of extracting a first fraction (27) of the second cooling air flow (12).

2. 2. The cooling line (1) according to claim 1, wherein the cooling line (1) is arranged such that a second fraction (28) not extracted from the second air stream mixes with the first air stream (8) in the first cooler (2) to obtain a mixture.

3. 3. The cooling line (1) according to claim 2, wherein the cooling line (1) comprises means (16, 30) for recovering the mixture.

4. The cooling line (1) according to any one of claims 1 to 3, wherein the air extraction device (17) is configured to extract air inside the second cooler (3).

5. 5. The cooling line (1) according to claim 4, wherein the air extraction device (17) comprises an extraction end (18) arranged inside the second cooler (3).

6. 6. The cooling line (1) of claim 5, wherein the second cooler (3) extends in an extension direction substantially parallel to the direction of movement of the particulate solid, the second cooler (3) extends over a length L measured in the extension direction, and the extraction end (18) is disposed within the second cooler (3) at a distance D measured in the extension direction from the material outlet (10) and the extraction end (18) that is 0.5L or more.

7. The cooling line (1) according to claim 6, wherein the distance D is between 0.7 L and 0.95 L.

8. 8. The cooling line (1) according to any one of claims 1 to 7, wherein the extraction device (17) comprises an extraction line (20) arranged inside the second cooler (3) and extending substantially parallel to the second cooler (3).

9. 9. The cooling line (1) according to claim 8, wherein the extraction line (20) and the second cooler (3) are substantially concentric.

10. The cooling line (1) according to any one of the preceding claims, wherein the at least one grate (4) of the first cooler (2) is fixed.

11. A cooling line (1) according to any one of the preceding claims, wherein the first cooler (2) comprises at least one crusher (26) for crushing the particulate solid.

12. 12. The cooling line (1) according to claim 11, wherein the first cooler (2) comprises a first portion (24) and a second portion (25) separated from each other by the crusher (26), and at least one fixed grid (4) in each portion (24, 25) is inclined so that the granular solid moves under the influence of the Earth's gravity.

13. A process for cooling a particulate solid by a cooling line (1) according to any one of claims 1 to 12, comprising the following operations: - circulation of at least a first air flow (8) in said first cooler (2) through at least one fixed grate (4); - circulation of a second air flow (12) in said second cooler (3) generated in part by said air extraction circuit (19) connected to said material outlet (10); - Extracting a first fraction (27) of said second air stream (12) in said second cooler (3).

14. 14. The cooling process of claim 13, wherein the extraction step is carried out so as to leave only a second fraction (28) of the second air stream (12) in the second cooler (3).

15. 15. The cooling process of claim 14, wherein the second fraction (28) of the second air flow (12) is directed towards the first air flow (8) to mix therewith, and the mixture is recovered for subsequent use by means (16, 30) for recovering the mixture.

16. 16. The cooling process according to claim 14 or 15, wherein the first air stream (8) contributes to a proportion of the mixture between 50% and 60% and the second air fraction (28) contributes to a proportion of the mixture between 40 and 50%.

17. 17. The cooling process of claim 16, wherein the first air stream (8) contributes to a proportion of the mixture of about 55% and the second air fraction (28) contributes to a proportion of the mixture of about 45%.

18. 16. The cooling process of claim 14 or 15, wherein the first fraction (27) extracted from the second air stream (12) is 65-80% of the second air stream (12).

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