Device and method for cooling aggregate for the production of fresh concrete

Abstract

The invention relates to a device and a method for cooling an aggregate for the production of fresh concrete. The device comprises a cooling drum (2) which is designed to continuously convey cooling water (16) and the aggregate in counter-flow while contacting one another, wherein the cooling drum (2) has a cylindrical housing (4), wherein a spiral conveyor (5) having a spiral coil (14) is arranged in the interior of the housing (4), wherein the cooling drum (2) has, in the longitudinal direction of the housing (4), an inlet for the aggregate and an outlet (7) for the cooling water (16) on one end and an outlet for the aggregate (6) and an inlet (6) for the cooling water (16) on the other end. According to the invention, the spiral conveyor (5) is a modification of a screw conveyor in which a central axial drive shaft is dispensed with.

Description

[0001] DEVICE AND METHOD FOR COOLING AGGREGATE FOR THE PRODUCTION OF FRESH CONCRETE

[0002] The invention relates to a device and a method for cooling aggregate for the production of fresh concrete.

[0003] To ensure that a concrete structure possesses the desired properties, the processing of fresh concrete must take place at predetermined temperatures or within specified temperature ranges. Typically, proper processing of fresh concrete requires that the concrete be at a temperature below 28°C, below 25°C, and possibly even below 20°C or 18°C, depending on the structure. Adherence to the specified temperatures during processing is of paramount importance, especially for large concrete structures such as dams, because otherwise the finished structure will not reliably meet the required properties regarding durability and load-bearing capacity.

[0004] Fresh concrete consists essentially of the following components: cement and water, as well as aggregates, which include in particular sand and rock. Furthermore, admixtures are used, which are primarily intended to influence the plasticity and deformability of the fresh concrete as desired.

[0005] Fresh concrete is generally defined as concrete that has not yet hardened. The cement paste, the mixture of water, cement, and other fine-grained components, has not yet set. This means that fresh concrete is still workable, i.e., malleable and partially flowable. While the cement paste is setting, the concrete is referred to as young concrete or green concrete. Once the cement paste has set, the concrete is called hardened concrete.

[0006] To achieve the desired target temperature of the fresh concrete, it is not possible to cool the fresh concrete mix made from the individual components. Instead, cooling must take place during production and / or one of the components must be pre-cooled.

[0007] It is known from the prior art that the water used in fresh concrete production can be pre-cooled or partially replaced with ice. Partial replacement of water with ice, in particular, achieves good cooling effects. However, the use of energy-intensive ice cooling systems is a disadvantage. Furthermore, even with the use of ice, the desired target temperature cannot always be reached because the percentage of water by mass is relatively small compared to the other components of the fresh concrete mix.

[0008] Pre-cooling the cement and / or sand is technically conceivable, but only very cumbersome and therefore expensive to implement, and also not very effective, since both sand and cement are used in only a relatively small proportion of the total quantity.

[0009] The aggregate accounts for by far the largest mass in relation to the final total weight. Therefore, by appropriately cooling the aggregate, the desired target temperature of the fresh concrete can be achieved simply based on its mass.

[0010] It is known from the prior art to cool rock using water. In this context, so-called sprinkler systems are known, which serve to sprinkle rock transported on a conveyor belt with water. Such systems are very complex and, in particular, too expensive for transportable concrete mixing plants. Furthermore, they require a lot of space.

[0011] Irrigation of stockpiles is also known from the prior art. This method utilizes the evaporative cooling effect of the water. However, in normal operation, rock is removed from a stockpile using a wheel loader, so uniform saturation and utilization of evaporative cooling are not possible. Since it is crucial for the desired fresh concrete quality that both the mix design and the target temperature are precisely maintained, water irrigation of rock on stockpiles is technically very complex and therefore costly, especially with regard to achieving the desired mix.

[0012] There is therefore a vital industrial interest in reducing the construction effort in plant engineering and the energy required in the production of fresh concrete.

[0013] The invention is therefore based on the objective of providing a device and a method with which the cooling of fresh concrete can be realized in an energy-efficient manner and with comparatively little effort.

[0014] To solve the problem, the invention proposes a device for cooling aggregate for the production of fresh concrete, comprising a cooling drum which is configured to continuously convey cooling water and aggregate in countercurrent flow with mutual contact, wherein the cooling drum has a cylindrical housing, wherein a spiral conveyor with a spiral helix is ​​arranged inside the housing, wherein the cooling drum has an inlet for the aggregate and an outlet for the cooling water at one end in the longitudinal direction of the housing, and wherein the cooling drum has an outlet for the aggregate and an inlet for the cooling water at the other end in the longitudinal direction of the housing.

[0015] To solve the problem, the invention further proposes a method for cooling an aggregate for the production of fresh concrete, in which an aggregate and cooling water are continuously conveyed in countercurrent flow and brought into contact with each other by means of a device according to the invention.

[0016] The cooling process according to the invention, using the device according to the invention, has several advantages. Firstly, it enables effective cooling. Tests have shown that the aggregate leaves the cooling drum at a temperature approximately 3°C higher than the inlet temperature of the cooling water. Therefore, when cooling is performed with water at 12°C, the aggregate leaves the cooling drum at a temperature of approximately 15°C.

[0017] It has also been shown that such a temperature is sufficient for the aggregate to achieve the desired target temperature for the finished concrete mix. This is, of course, contingent on the aggregate being processed promptly after cooling in the cooling drum. The entire process is very energy-efficient, as it does not require the use of ice or extremely cold water for cooling the aggregate.

[0018] Since the cooling rate or cooling using the device according to the invention is very effective and the cooled rock only needs to be about 3°C ​​warmer than the water used for cooling, it is perfectly sufficient to use cooling water at a low double-digit Celsius temperature, particularly between 10°C and 15°C. A further advantage is that the device according to the invention is very simple and robust in its construction. The supply of cooling water or of the aggregate to be cooled is also technically relatively straightforward.

[0019] From a process perspective, it is therefore preferred that the temperature of the cooling water is set to a predeterminable cooling temperature before contacting the aggregate, which is a maximum of 5 °C, preferably a maximum of 4 °C, and in particular a maximum of 3 °C, below the predeterminable target temperature of the aggregate after contacting has been completed.

[0020] The device according to the invention enables a very efficient process. In particular, compared to cooling with ice, it allows for very energy-efficient processing. Thus, the process according to the invention allows for savings of 30 to 50% in primary energy compared to cooling with ice. This also has the advantage that a machine for ice production can be completely dispensed with, which is also economically advantageous.

[0021] The primary energy savings achieved with the process according to the invention result in particular from the fact that, to achieve the desired fresh concrete temperature, it is sufficient to use water to cool the aggregate at a temperature of, for example, 15°C. At such a cooling water temperature, the aggregate temperature in the intended process is approximately 18°C.

[0022] To achieve a cooling water temperature of, for example, 15°C, it is cooled in a plate heat exchanger in a counterflow with fresh water. The fresh water, taking into account a temperature variation of 3°C, has a temperature of 12°C. To maintain such a fresh water temperature, an evaporation temperature of approximately 9°C is required.

[0023] In contrast, the production of ice in the ice generator operates at an evaporation temperature of approximately -10°C to -25°C. The inventive method thus allows for a significantly higher evaporation temperature compared to the prior art, resulting in primary energy savings of up to 50%. Nevertheless, when the inventive method is carried out as intended, it is ensured that the desired target temperature of the fresh concrete can be achieved reproducibly.

[0024] The device and method according to the invention offer further advantages: Contact with the cooling water results in complete saturation of the aggregate with water. The cooled aggregate thus has a defined water content. This is particularly important for maintaining the concrete mix design. The amount of water to be added to the aggregate for concrete formation can be reduced by the defined amount of water contained in the saturated and cooled aggregate. In this context, it is also advantageous that the amount of aggregate can be reduced compared to the amount required for dry aggregate. It has been shown that this can result in savings of approximately 15% to 20% of the additives. This represents a particularly advantageous saving that roughly corresponds to the investment costs for a device according to the invention.

[0025] According to the invention, a cooling drum with a spiral conveyor is used for cooling the rock. This cooling drum is preferably horizontally oriented and is supplied with the aggregate to be cooled on one side and with cooling water on the other. Due to an internal spiral helix of the spiral conveyor, the warm aggregate is transported from the inlet to the outlet. The cooling water, introduced in the opposite direction, cools the aggregate as it is transported from the inlet to the outlet.

[0026] According to a preferred feature of the invention, the spiral helix is ​​connected to an inner wall of the housing in a rotary motion-coupled manner at least at one end in the longitudinal direction and / or on the outer circumference in the radial direction. A spiral conveyor, as defined in the invention, is a modification of a screw conveyor in which a central axial drive shaft is omitted. The drive of the spiral conveyor is therefore preferably achieved via a corresponding coupling with the housing. The housing, in turn, preferably has a drive shaft which is connected to a corresponding drive provided by the device, in particular a motor, preferably an electric motor.

[0027] According to a preferred feature of the invention, the housing and spiral helix are arranged coaxially with respect to their respective axes of rotation and horizontally aligned with respect to the vertical direction. "Load direction" in the context of the invention refers to the local direction of the acceleration due to gravity. This advantageously ensures uniform contact between the aggregate and the cooling water. A flow gradient within the cooling drum is therefore avoided.

[0028] Preferably, the inlet for the cooling water is smaller than its outlet. This ensures that the cooling water can only flow through the cooling drum from the cooling water inlet to the cooling water outlet. In particular, it is provided that the inlet and outlet for the cooling water are each designed as a circular hole, which are arranged coaxially with respect to the axis of rotation of the housing, with the radial extent of the cooling water outlet being larger than the radial extent of the cooling water inlet. The process preferably involves setting a cooling water level within the cooling drum that lies radially above the cooling water outlet but below the cooling water inlet.

[0029] According to a preferred feature of the invention, the spiral helix has radially extending recesses, in particular slots and / or holes, on its inner circumference, with the recesses extending axially through the spiral helix. This improves the flow characteristics of the cooling water within the cooling drum. In this respect, it is particularly advantageous if immediately adjacent recesses are arranged equidistantly from one another in the direction of the helix and if the recesses are evenly distributed over the entire spiral helix.

[0030] According to a preferred feature of the invention, the spiral conveyor and / or the housing has a length of 8 m to 12 m and a diameter of 1.5 m to 2.3 m. This provides a conveying distance at the end of which the target temperature of the aggregate is reliably reached. From a process perspective, it is preferred that the aggregate and cooling water are in contact with each other in counterflow over a conveying distance of 8 to 12 meters. Furthermore, this makes it possible to arrange the entire device, in particular the cooling drum, and preferably the cooling circuit, within a conventional 40' container (shipping container), which greatly simplifies transport. Moreover, the container with the device can be positioned directly, i.e., in the immediate vicinity of a mixing hopper, so that the cooled aggregate can be processed immediately after leaving the cooling drum.

[0031] According to a preferred feature of the invention, a cooling water circuit is provided which fluidically connects the cooling water outlet of the cooling drum with the cooling water inlet of the cooling drum. Preferably, the cooling water circuit includes a settling tank for separating rock particles originating from the aggregate. The heated cooling water leaving the cooling drum is first directed into the settling tank. Here, suspended particles can settle to the bottom, primarily due to gravity. Alternatively or additionally, it is preferably provided that the settling tank includes a particle filter, particularly in the form of a geotextile. The particle filter preferably has a diameter of 1.1 to 1.3 m and a height of 1.7 to 2.1 m.

[0032] In terms of the process, it is preferred that the cooling water is circulated, whereby heated cooling water is first cleaned of components of the aggregate after contact with the aggregate.

[0033] Preferably, the cooling water circuit further comprises a heat exchanger, in particular a plate heat exchanger, located downstream of the slurry tank in the direction of flow of the cooling water, for cooling and adjusting the temperature of the cooling water to a predetermined cooling temperature. The heat exchanger, in particular the plate heat exchanger, is preferably operated in counterflow with a cooling medium in the form of fresh water, which is preferably circulated in a second cooling circuit.

[0034] It is particularly preferred that the cooling water circuit has a control unit which has at least one sensor for measuring an actual value of the cooling water temperature, which is arranged in the flow path of the cooling water and upstream of the heat exchanger, and which has a data processing unit which is configured to compare the sensor-measured actual value with a target cooling temperature stored in the data and is configured, in the event of a predefinable deviation of the actual value from the target cooling temperature, to control the heat exchanger to which it is connected in such a way that the actual value is adjusted to the target cooling temperature within a predefinable tolerance.

[0035] The process preferably involves adjusting the purified cooling water to the desired cooling temperature after it passes through the evaporation tank. It is particularly preferred that the purified cooling water is passed through a heat exchanger to achieve this temperature adjustment, using fresh water as the cooling medium. Furthermore, it is preferred that the cooling temperature is adjusted by continuously comparing a continuously sensor-monitored actual value with a stored target value, where the target value is defined by a specific cooling water temperature. If the actual value deviates from the target value, the heat exchanger is activated by the control system to correct this deviation.

[0036] According to a preferred feature of the invention, a first conveying means, in particular a first conveyor belt, is provided, which serves for the continuous transport of the aggregate to be cooled to the cooling drum. The first conveying means is arranged in the conveying direction of the aggregate upstream of the cooling drum. This simplifies the process through automation.

[0037] Furthermore, a second conveying element, in particular a second conveyor belt, is preferably provided, which serves for the continuous transport of the cooled aggregate and preferably for the conveying connection to a mixing hopper for mixing fresh concrete. The second conveying element is located downstream of the cooling drum in the conveying direction of the aggregate. This simplifies the process through further automation. According to a particularly preferred feature of the invention, the second conveying element has a thermally insulated housing. This ensures, particularly in regions of the world with intense solar radiation, that the cooled aggregate is maintained at the target temperature on its way to further processing.

[0038] The process preferably involves transporting the cooled aggregate directly to a mixing bunker where fresh concrete is produced. Preferably, the cooled aggregate is mixed with water and cement.

[0039] The use of a slurry tank, as described above, is purely optional. A slurry tank is particularly useful when cooling the cooling water with fresh water is carried out using plate heat exchangers. The use of a slurry tank is preferred in this case because it prevents the plate heat exchangers from becoming clogged by rock particles, debris, and / or other impurities carried in the cooling water. Therefore, the use of a slurry tank is preferred when subsequent cooling of the cooling water is carried out using plate heat exchangers.

[0040] According to an alternative and preferred embodiment of the invention, a heat exchanger unit, which is not a plate heat exchanger, is used to cool the cooling water. Such a heat exchanger unit is preferably designed as an open heat exchanger. It is particularly preferred to form the open heat exchanger from individual vats connected in series in terms of flow characteristics. Such a vat is formed by a container, preferably a container with a cylindrical shape. The containers are designed without lids, i.e., they are open at the top. Therefore, such a heat exchanger unit is also an open heat exchanger.

[0041] At least two vats of the type described above are provided, but preferably three vats, four vats or even more vats.

[0042] The cooling water exiting the cooling drum at the water outlet is pumped via a flow-through connection into the first vessel of the open heat exchanger. From there, the cooling water flows from vessel to vessel until it reaches the last vessel of the heat exchanger. From there, the cooled water is returned to the cooling drum. The last vessel of the heat exchanger is therefore in flow-through connection with the cooling water inlet of the cooling drum.

[0043] To cool the cooling water using appropriately tempered fresh water, plates are used in the intended application, through which the fresh water flows. These plates are immersed in the individual vats. Three, four, five, or even more individual plates can be provided per vat. These plates are connected to an inlet manifold on one side and an outlet manifold on the other. In the intended application, appropriately tempered fresh water is supplied through the inlet manifold. From there, the individual plates connected to it are flooded with fresh water, or rather, the fresh water flows through the plates connected to it. These plates are immersed in the individual vats of the heat exchanger, so that the cooling water contained within is cooled, as it is in direct contact with the individual plates.In normal use, the cooling plates arranged in the vats are surrounded by the cooling water located in the vats.

[0044] On the flow outlet side, the individual plates are connected to the outlet manifold, so that the fresh water heated after heat transfer can be discharged via this manifold.

[0045] The use of the aforementioned open heat exchanger has the particular advantage that the rock particles, impurities, and / or other contaminants carried along by the cooling water cannot lead to a blockage of the heat exchanger, as is the case with the use of a plate heat exchanger. Therefore, the use of a floatation tank can be advantageously dispensed with.

[0046] To prevent rock particles, contaminants, and / or other impurities carried by the cooling water from washing out the aggregate, it is further proposed that each tub be equipped with an agitator. Such an agitator ensures that the cooling water in a tub is constantly stirred and thus continuously circulated, keeping any rock particles, contaminants, and / or other impurities in motion and suspended, thereby ensuring their return to the aggregate. This advantageously allows for adherence to the mix design for the fresh concrete to be produced.

[0047] A further advantage of the open heat exchanger is that, lacking a required slurry tank, it can be compactly housed in its own enclosure. In particular, it is possible to house the open heat exchanger in a container, preferably a standard 40-foot container. Since the aforementioned cooling drum can also be housed in such a container, the result is a compact overall design consisting of two individual containers that can be stacked on top of each other. This advantageously allows for easy transport and simple on-site assembly. The container with the cooling drum is preferably positioned at the bottom, and the container housing the open heat exchanger is positioned above it, resting on the container containing the cooling drum. The system configured in this way is ready for operation without any further construction work.All that's needed is a fresh water supply and an electrical connection.

[0048] According to a further feature of the invention, the aggregate is dewatered after passing through the cooling drum as intended. "Dewatered" in the context of the invention means that cooling water adhering to the surface of the aggregate is removed. This is advantageous for two reasons. Firstly, it prevents unwanted carryover of cooling water. Secondly – ​​and this is a significant advantage – it ensures adherence to the recipe for the subsequent fresh concrete mix. The latter also has the further advantage that the aggregate exiting the cooling drum can be directly processed further, for example, in a concrete mixing plant.

[0049] If the aggregate is not dewatered as described above, the cooling water carried along with the aggregate will drip off. If the aggregate is temporarily stored in a silo, this dripping water collects at the bottom of the silo. If a concrete mixing plant is then fed from this silo, the batch near the bottom of the silo will be particularly moist due to the accumulated dripping water, or the last batch of aggregate will contain a higher water content compared to the other batches. This can lead to unintended inconsistencies in the mix design. The aggregate dewatering process provided according to the invention, which takes place after the aggregate has passed through the cooling drum, eliminates this disadvantage.

[0050] A dewatering screen is preferably used to dewater the aggregate. This dewatering screen is designed like a circulating conveyor belt and has corresponding openings through which dripping water can pass and then be conveyed away. The dripping water is preferably collected in a suitable trough so that it can be gathered and then returned to the cooling water circuit, thus enabling virtually loss-free operation of the cooling water circuit.

[0051] As a result, the aforementioned alternative of the inventive design is preferred, since a floatation tank can be dispensed with and, synergistically, a compact overall design of the entire system is made possible, as the cooling drum on the one hand and the heat exchanger on the other can each be housed in a single container. Furthermore, adherence to the recipe can be maintained, as unwanted carryover of aggregate particles is avoided.

[0052] In combination with both the first and second alternatives of the invention, drying of the aggregate is provided after it has passed through the cooling drum as intended. Preferably, a dewatering screen, designed as a conveyor belt, serves for drying. This screen is connected to the cooling drum on the aggregate outlet side. It allows residual cooling water adhering to the surfaces of the individual aggregate particles to drip off and then be removed. Unwanted carryover of cooling water is thus avoided, and in this context, it is particularly advantageous that reproducible and controllable consistency of the fresh concrete mix is ​​maintained. The invention is explained below with reference to a preferred embodiment.

[0053] This shows

[0054] Fig. 1 shows a schematic representation of a device according to the invention;

[0055] Fig. 2 shows the interior of the cooling drum according to the invention in an axial view and

[0056] Fig. 3 shows a schematic perspective view of the invention.

[0057] Device.

[0058] Figure 1 shows the device 1 according to the invention. The device 1 has a cooling drum 2 and a first cooling circuit 3.

[0059] The cooling drum 2 has a cylindrical housing 4 made of metal, preferably steel, which has a length of 8 m to 12 m, preferably 9 m to 11 m, and a diameter of 1.0 m to 2.5 m, preferably 1.5 m to 2.2 m. The housing 4 has an internal spiral conveyor 5, as shown in detail in Figure 2.

[0060] The housing 4 of the cooling drum 2 has a cooling water inlet 6 at one end and a cooling water outlet 7 at the other end, extending axially. The cooling water inlet 6 has a smaller cross-section than the cooling water outlet 7. This ensures that the cooling water does not leave the cooling drum 2 via the cooling water inlet 6, but can only flow through the cooling drum 2 from the cooling water inlet 6 to the cooling water outlet 7. The cooling water therefore leaves the cooling drum 2 through the cooling water outlet 7, after passing through the cooling drum 2 in the axial direction, specifically in the conveying direction 8.

[0061] In this case, the cooling water inlet 6 and the cooling water outlet 7 are each designed as a circular opening in the respective end wall of the cylindrical housing 4. The cooling water inlet 6 and the cooling water outlet 7 are each arranged coaxially with respect to the axis of rotation of the housing 4. The radial extent of the cooling water outlet 7 is greater than the radial extent of the cooling water inlet 6. The process preferably involves setting a cooling water level within the cooling drum that lies radially above the cooling water outlet 7 but below the cooling water inlet 6.

[0062] The cooling water flows through the cooling drum 2 in the conveying direction 8. The aggregate to be cooled – also called rock fraction – is conveyed through the cooling drum 2 in the opposite direction 9. The inlet 6 for the cooling water forms the outlet for the aggregate, and the outlet 7 for the cooling water forms the inlet for the aggregate.

[0063] The temperature of the cooling water supplied to the cooling drum 2 at the cooling water inlet can be adjusted as required. The cooling water temperature depends on the desired target temperature of the fresh concrete being produced using cooled aggregate. For example, if a target temperature of 25°C is desired for the fresh concrete, then, assuming the sand, cement, and water temperatures are appropriate, a temperature of 18°C ​​relative to the aggregate is required. Generally, a temperature difference of 3°C is established in cooling drum 2 between the desired aggregate temperature and the cooling water temperature. Therefore, if an aggregate temperature of 18°C ​​is required, cooling water at a temperature of 15°C must be supplied to the cooling drum.

[0064] As will be explained in more detail below, the cooling water is cooled in a second cooling circuit 12 before being fed to the cooling drum 2. The cooling of the cooling water in the second cooling circuit 12 is achieved by means of a heat exchanger, preferably a counterflow plate heat exchanger 11. Such a heat exchanger has a temperature difference of approximately 3°C. Therefore, to reliably achieve an aggregate temperature of 18°C, the cooling water supplied to the cooling drum 2 must be set to 12°C on the plate heat exchanger side. This results in a temperature difference of 6°C between the desired aggregate temperature and the temperature to be set for the cooling water in the second cooling circuit 12.

[0065] Cooling water at a temperature of 12°C can be produced at an evaporation temperature of approximately 9°C. In contrast to prior art cooling methods using ice, this advantageously leads to a saving of approximately 30% to 50% in primary energy consumption at the refrigeration unit, i.e., the compressor. Unlike ice production, an evaporation temperature of -10°C to -25°C is no longer required, but only approximately 9°C, as explained above. The device according to the invention offers the synergistic advantage that, depending on the desired target temperature of the fresh concrete and thus the desired target temperature of the cooled aggregate, higher evaporation temperatures can also be used. This variability depending on the target temperature of the fresh concrete is not possible with ice production.

[0066] The first cooling circuit 3 connects the cooling water outlet 7 to the cooling water inlet 6 via a flow-related system. Cooling circuit 3 is equipped with appropriate pumps and valves (not shown) to generate the flow. Upstream of the cooling drum 2, cooling circuit 3 includes a settling tank 10 for separating rock residues, particularly suspended particles. The settling tank 10 contains a particle filter (not shown), for example, in the form of a geotextile.

[0067] Upstream of the flotation tank 10, the cooling circuit 3 provides a counterflow plate heat exchanger 11 for adjusting the heated cooling water to the cooling temperature. Fresh water is used as the cooling medium and is circulated in a second cooling circuit 12.

[0068] Upstream of the plate heat exchanger 11, a temperature sensor 13 is arranged in the flow path of the cooled cooling water. This sensor is connected via signal transmission to a control unit (not shown), which in turn is connected via control transmission to the plate heat exchanger 11 and / or flow control elements (not shown), such as pumps and / or valves.

[0069] The cooling drum 2 has a drive shaft (not shown) which is connected to a drive unit (not shown) in the form of an electric motor. This causes the housing 4 – and, via rotary coupling, also the spiral conveyor 5 – to rotate around the longitudinal axis of the cylindrical housing 4. The drive unit has a control system that allows the rotational speed of the housing to be regulated.

[0070] As can be seen from an overall view of the diagram in Fig. 1, the cooling water, which cools the aggregate in the intended application, is circulated in the closed cooling circuit 3. The cooling water, set to a preselected cooling temperature, is fed into the cooling drum 2 at the cooling water inlet. It then flows longitudinally through the cooling drum 2, from right to left with respect to the plane of the drawing in Fig. 1, until it reaches the cooling water outlet 7. As it passes through the cooling drum 2, the cooling water heats up due to the cooling of the aggregate. Thus, a heat transfer occurs from the aggregate to the cooling water.

[0071] The heated cooling water exiting cooling drum 2 at the cooling water outlet is then directed to the simmering tank 10. From there, it flows to the plate heat exchanger 11. Here, it is cooled without contact in a counterflow process using fresh water circulating in a separate, closed cooling circuit 12. The cooling water exiting the plate heat exchanger 11 has cooled to the desired temperature, which is monitored by the temperature sensor 13 and, if necessary, adjusted or regulated according to temperature signals. The cooled cooling water is then fed back to cooling drum 2 at the cooling water inlet. From there, it flows back through cooling drum 2 in the conveying direction 8.

[0072] The design of a closed cooling circuit 3 has the particular advantage that any rock particles carried along with the cooled aggregate are continuously circulated, thus preventing any unwanted discharge of rock particles from the aggregate. The quality of the aggregate therefore remains unchanged. If necessary, unwanted rock particles and / or other substances are separated in the settling tank 10, especially those that would impede continuous cooling operation by clogging or blocking individual pipes.

[0073] The closed cooling circuit 3 also offers the advantage of continuous process operation, so that aggregate can be cooled virtually on demand by a concrete plant, and in the quantity required by the plant to produce the fresh concrete to be processed subsequently. The device according to the invention can therefore be operated by a concrete plant on demand as needed. A lead time, such as that required for ice production, for example, is advantageously not required in advance. The device according to the invention is therefore very flexible in its application, both with regard to the operating time or period and with regard to the total quantity of cooled aggregate to be produced.

[0074] Figure 2 shows the interior of the housing 4 of the cooling drum 2. The spiral conveyor 5, the cooling water inlet 6 and the cooling water outlet 7 can be seen.

[0075] The spiral conveyor 5 provides a spiral helix 14. The spiral helix 14 is coupled to the inner wall of the cylindrical housing 4 on its outer circumference and is attached to the inner wall for this purpose.

[0076] Furthermore, the spiral helix 14 provides radially extending slots 15 on its inner circumference, which extend completely through the spiral helix 14 in the axial direction. This improves the flow characteristics of the cooling water within the cooling drum 2. To further improve the flow characteristics, adjacent slots 15 are arranged equidistant from each other in the direction of the helix. Additionally, a plurality of slots 15 are evenly distributed over the entire spiral helix 14.

[0077] Also visible is the cooling water 16, which flows through the cooling drum 2 from the cooling water inlet 6 to the cooling water outlet 7 and thereby contacts the unseen aggregate.

[0078] Figure 3 shows the device 1 according to the invention in a schematic perspective view.

[0079] As shown in Figure 3, a feed point 17 serves to supply the cooling drum 2 with aggregate. This feed point is designed in the form of a funnel and is fluidically connected to a conveyor belt and / or similar conveying device. During operation, aggregate can thus be fed into the cooling drum 2 via the feed point 17 through the cooling water outlet 7. The aggregate thus introduced into the cooling drum 2 is then conveyed through the cooling drum 2 in the conveying direction 9 as described above, until it reaches the cooling water inlet 6, through which the cooled aggregate is discharged.

[0080] The spiral conveyor 5 serves to convey the aggregate in the conveying direction 9, and has a spiral helix 14 equipped with slots 15, which is twisted and received by the housing 4 of the cooling drum 2.

[0081] The cooling water outlet 7 is fluidically connected to a connection nozzle 18. This connection nozzle 18 serves as the fluidic connection to a pipe or line through which the cooling water 16 is guided in a closed flow circuit 3. Cooling water 16, which passes through the cooling drum 2, thus enters the system via the connection nozzle 18, from where it is then transported towards the plate heat exchanger 11 (not shown in Figure 3).

[0082] A drive roller 19 serves to rotate the cooling drum 2; the housing 4 of the cooling drum 2 rests on this roller, transmitting force. The drive roller 19 is driven by a motor, in particular an electric motor.

[0083] Aligned parallel to the drive roller 19, a further roller, not visible in Figure 3, is provided, which as a traveling roller supports the housing 4, which is circular in cross-section, on the rear side with reference to the drawing plane according to Figure 3.

[0084] The entire cooling drum 2 is housed in an enclosure 20. This enclosure 20 can, for example, be a standard 40-foot container. This ensures easy transport of the entire device 1 using conventional means of transport. In particular, transport by ship and / or truck to a desired place of use is easily facilitated. Reference numeral

[0085] 1 Device

[0086] 2 cooling drums

[0087] 3 First cooling water circuit

[0088] 4 cases

[0089] 5 spiral conveyors

[0090] 6 Coolant inlet

[0091] 7 Cooling water outlet

[0092] 8. Cooling water flow direction

[0093] 9. Conveying direction of aggregate

[0094] 10 floatation tanks

[0095] 11 plate heat exchangers

[0096] 12 Second cooling water circuit

[0097] 13 Temperature sensor

[0098] 14 spiral helix

[0099] 15 slots

[0100] 16 Cooling water

[0101] 17 Departure point

[0102] 18 connection spigots

[0103] 19 Drive roller

[0104] 20 Enclosure

Claims

Patent claims 1. Device for cooling an aggregate for the production of fresh concrete, characterized by a cooling drum (2) which is configured to continuously convey cooling water (16) and the aggregate in countercurrent flow with mutual contact, wherein the cooling drum (2) has a cylindrical housing (4), wherein a spiral conveyor (5) with a spiral helix (14) is arranged inside the housing (4), wherein the cooling drum (2) has an inlet for the aggregate and an outlet (7) for the cooling water (16) at one end in the longitudinal direction of the housing (4), and wherein the cooling drum (2) has an outlet for the aggregate and an inlet (6) for the cooling water (16) at the other end in the longitudinal direction of the housing (4).

2. Device according to claim 1, characterized in that the spiral helix (14) is rotatably connected in the longitudinal direction at least on one end and / or in the radial direction on the outer circumferential side to an inner wall of the housing (4).

3. Device according to claim 2, characterized in that the housing (4) and spiral helix (14) are arranged coaxially with respect to their respective axis of rotation and are horizontally aligned with respect to the plumb line.

4. Device according to claim 3, characterized in that the inlet (6) and outlet (7) for the cooling water are each formed in the form of a circular hole, which are each arranged coaxially with respect to the axis of rotation of the housing (4), wherein the radial extent of the outlet for the cooling water (16) is larger than the radial extent of the inlet (6) for the cooling water (16).

5. Device according to one of claims 1 to 4, characterized in that the spiral conveyor (5) has a length of 8 m to 12 m and a diameter of 1.5 m to 2.3 m.

6. Device according to one of claims 4 or 5, characterized in that the spiral helix (14) extends radially in the inner circumferential direction has recesses, in particular slots (15) and / or holes, wherein the recesses extend through the spiral helix (14) in an axial direction.

7. Device according to claim 6, characterized in that immediately adjacent recesses are arranged equidistantly apart from each other in the direction of rotation and that the recesses are arranged evenly distributed over the entire spiral helix (14).

8. Device according to one of claims 3 to 7, characterized by a cooling circuit (3) which fluidically connects the outlet (7) for the cooling water (16) of the cooling drum (2) with the inlet (6) for the cooling water (16) of the cooling drum (2), wherein the cooling circuit (3) has a floatation basin (10) for separating rock particles originating from the aggregate and a heat exchanger (11) arranged downstream of the floatation basin (10) in the direction of flow of the cooling water (16) for cooling and adjusting the temperature of the cooling water (16) to a predetermined cooling temperature.

9. Device according to claim 8, characterized in that the floatation basin (10) has a particle filter, in particular in the form of a geotextile.

10. Device according to claim 9, characterized in that the particle filter has a diameter of 1.1 to 1.3 m and a height of 1.7 to 2.1 m, 11. Device according to one of claims 8 to 10, characterized in that the cooling circuit (3) has a control unit which has at least one sensor (13) for measuring an actual value of the temperature of the cooling water (16), which is arranged in the flow path of the cooling water (16) and upstream of the heat exchanger (11), and which has a data processing unit which is configured to compare the sensor-measured actual value with a target cooling temperature stored in the data and is configured to, in the event of a predefinable deviation of the actual value from the target cooling temperature, to adjust the heat exchanger (11), with which it is connected in terms of control technology, in such a way that the actual value is adjusted to the target cooling temperature within a predefinable tolerance. is being discontinued.

12. Device according to one of claims 8 to 11, characterized by a first conveying means, in particular a first conveyor belt, for the continuous transport of the aggregate to be cooled to the cooling drum (2), which is arranged in the conveying direction (9) of the aggregate in front of the cooling drum (2), and characterized by a second conveying means, in particular a second conveyor belt, for the continuous removal of the cooled aggregate and the conveying connection with a mixing hopper for the mixing of fresh concrete, which is arranged downstream of the cooling drum (2) in the conveying direction (9) of the aggregate.

13. Method for cooling an aggregate for the production of fresh concrete, in which an aggregate and cooling water (16) are continuously conveyed in countercurrent flow and brought into contact with each other by means of a device according to one of claims 1 to 13.

14. Method according to claim 13, characterized in that the temperature of the cooling water (16) is set to a predeterminable cooling temperature before contacting the aggregate, which is 6 °C, preferably 4 °C, in particular 3 °C, below the predeterminable target temperature of the aggregate after completed contacting.

15. Method according to claim 14, characterized in that the cooling water (16) is circulated, wherein heated cooling water is first cleaned of components of the aggregate after contact with the aggregate and then the cleaned cooling water (16) is adjusted to the cooling temperature.

16. Method according to claim 15, characterized in that the purified cooling water (16) is passed through a heat exchanger (11) to adjust it to the cooling temperature, wherein fresh water is used as the cooling medium.

Images