Method and System for Processing Concrete Granules

Abstract

The disclosure provides a method and a system for processing concrete granulate for subsequent recycling of the concrete granulate. In the method, a container of the system is filled with concrete granulate, said container being gas-tight at least in some regions. Subsequently, gas comprising CO2 is fed, continuously or noncontinously, according to a level of CO2 absorption by the concrete granulate in the container, said level being determined by means of at least one sensor. After a predefined CO2 saturation of the concrete granulate has been detected, the concrete granulate, which have been enriched with CO2, are removed.

Claims

1. A method for processing concrete granulate for subsequent recycling of the concrete granulate, comprising the following method steps: a. Filling an at least partially gas-tight container with concrete granulate; b. Supplying a volume flow of gas comprising CO2 into the container as a function of a measure of an occurred CO2 absorption by the concrete granulate in the container, the measure of the occurred CO2 absorption being determined via at least one sensor; c. Determining whether a predefined CO2 saturation of the concrete granulate has been reached and, if not, continuing with method step b; and d. In response to a determination that the predefined CO2 saturation of the concrete granulate has been reached, removing the concrete granulate enriched with CO2.

2. The method according to claim 1, wherein the gas fed into the container comprises 95% to 100% CO2.

3. The method according to claim 1, wherein the measure of the occurred CO2 absorption is determined via a measurement of at least one of a pressure and a CO2 concentration by the at least one sensor.

4. The method according to claim 3, wherein the measure of the occurred CO2 absorption additionally takes into account at least one of a measured temperature, a measured weight, and a measured relative humidity in the container.

5. The method according to claim 1, further comprising reducing or temporarily interrupting the supplied volume flow of gas when a desired filling level of the container with at least one of the gas and a predefined CO2 concentration in the container is reached.

6. The method according to claim 5, wherein the reduced or temporarily interrupted volume flow of gas comprising CO2 compensates for the CO2 already absorbed by the concrete granulate arranged in the container.

7. The method according to claim 1, wherein the predefined CO2 saturation of the concrete granulate is reached, when the change in the measure of the occurred CO2 absorption falls below a limit value in a predefined time interval.

8. The method according to claim 1, wherein, after reaching the predefined CO2 saturation, excess gas is led from the container into a collecting container which is filled with further concrete granulate which at least partially absorbs the excess gas.

9. The method according to claim 8, wherein the method steps b to d according to claim 1 are repeated in the collecting container.

10. A system for processing concrete granulate for subsequent recycling of the concrete granulate, comprising a. an at least partially gas-tight container with i. at least one opening configured for at least one of filling and extracting the concrete granulate, and ii. an inlet configured to supply a gas comprising CO2 into the container, wherein the inlet is fluidically operatively connectable to a storage tank via a supply line, and b. an inlet valve configured to control a supplied volume flow of the gas into the container; c. at least one sensor configured to determine a measure of an occurred CO2 absorption by the concrete granulate in the container; and d. a control unit which is operatively connected to the at least one sensor and to the inlet valve and which is configured to control the supplied volume flow via the inlet valve.

11. The system according to claim 10, wherein the control unit is configured to carry out the following sequence of steps automatically: a. Supply of the volume flow of gas comprising CO2 into the container as a function of the measure of the occurred CO2 absorption by the concrete granulate in the container determined via the at least one sensor; b. Determination whether a predefined CO2 saturation of the concrete granulate has been reached.

12. The system according to claim 10, wherein at least one sensor is arranged in the container and is at least one of a pressure sensor for measuring a pressure and a concentration sensor for measuring a CO2 concentration.

13. The system according to claim 12, wherein several concentration sensors are arranged one above the other in the container in the direction of gravity.

14. The system according to claim 10, wherein the inlet comprises a plurality of gas inlet nozzles which are arranged in a matrix-like manner in at least one of a receiving space of the container, on at least one side wall of the container, and on a base of the container.

15. The system according to claim 10, wherein the system comprises a collecting container for receiving further concrete granulate, configured to be fluidically operatively connected to the container via a discharge line of the container.

16. A concrete granulate produced according to claim 1, wherein the concrete granulate have a CO2 saturation of at least 5 kg CO2 per 1000 kg.

17. A concrete comprising the concrete granulate according to claim 16.

18. The method according to claim 2, wherein the gas fed into the container is renewable CO2.

19. The method according to claim 5, wherein the predefined CO2 concentration in the container is above 95%.

20. The method according to claim 8, wherein the concrete granulate completely absorbs the excess gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Aspects of the disclosure are explained in more detail with reference to the examples of embodiments shown in the following figures and the accompanying description. Showing:

[0037] FIG. 1A first version of a system for processing concrete granulate according to the disclosure;

[0038] FIG. 2A second version of a system for processing concrete granulate according to the disclosure.

DETAILED DESCRIPTION

[0039] FIG. 1 shows a schematic view of a first version of a system 1 according to the disclosure for processing concrete granulate 2. The system 1 comprises a storage tank 3 for storing a gas comprising CO2 and at least one at least partially gas-tight container 4, 12. In the embodiment shown, a first container 4 and a second (collecting) container 12 are present. Both containers 4, 12 may be closable in a gas-tight manner and each comprise (in an opened state) at least one opening (not shown) for filling and/or extracting the concrete granulate 2. The first container 4 comprises an inlet 5 for feeding the gas into the container 4, which can be fluidically operatively connected to the storage tank 3 via a supply line 6. The second container 12 is operatively connected to the discharge line 14, which is operatively connected to the outlet 13 of the first container. An inlet valve 7 is arranged in the supply line 6, between the storage tank 3 and the first container 4, which is used to control a supplied volume flow of gas into the container 4. The inlet valve 7 can be a proportional valve. The inlet 5 may comprise a plurality of gas inlet nozzles. For rapid filling, gas inlet nozzles may be arranged in a matrix-like manner in the receiving space and/or in the base and/or in the at least one side wall of the container 4 (not shown). A pump 17 and an outlet valve 18 may be arranged in the pipe between the first and second containers 4, 12. The pump 17 can be designed to draw gas from the storage tank 3 into the first container 4 (when the inlet valve 7 and outlet valve 18 are open). For this purpose the pump 17 may be a vacuum pump. In addition, a CO2 concentration sensor 8 can be arranged in the discharge line of the first container 4 (or in the line between the two containers 4, 12 respectively). This is used to monitor how much CO2 is discharged from the container 4.

[0040] Further sensors 8, 9, 10 are arranged in the first container 4. Based on the measured values of these sensors, a measure of the occurred CO2 absorption by the concrete granulate 2 can be determined, as described above. A control unit 11 is used to control the supply of gas depending on the measure of the occurred CO2 absorption. For this purpose, the sensors 8, 9, 10, the inlet valve 7, the outlet valve 18 and the pump 17 are operatively connected to the control unit 11. The inlet valve 7 and/or the outlet valve 18 may comprise a flow sensor. The control unit 11 can in particular be designed to automatically control the gas supply and/or the gas discharge until a predefined CO2 saturation of the concrete granulate 2 in CO2 is reached.

[0041] For the initial filling of the container 4 comprising the concrete granulate 2 with the gas, the inlet valve 7 and the outlet valve 18 can first be opened. The pump 17 can then draw the gas from the storage tank 3 into the container 4. The concentration sensor 8 in the discharge line 14 of the container 4 can monitor the CO2 concentration. When a desired maximum CO2 concentration is reached in the container 4, the outlet valve 18 can be closed. The inlet valve 7 can also be closed at least temporarily. The sensors 8, 9, 10 in the container 4 can measure the pressure, the CO2 concentration and the temperature in the container. The measured values are used by the control unit to determine a measure for the absorption of CO2. Depending on the measure for the absorption, gas comprising CO2 is fed into the container so that an optimal and as uniform as possible CO2 saturation, respectively enrichment, of the concrete granulate 2 with CO2 takes place. When the predefined CO2 saturation is reached, the excess gas can be discharged from the first container 4. Advantageously, this is filled, as in the case shown, into the collection container 12, which is also filled with concrete granulate 2. In this, the excess gas can advantageously be completely absorbed by the concrete granulate 2 in the collecting container 12. This can be monitored in particular by a further CO2 concentration sensor 8, which is arranged in a discharge line of the collecting container 12. Alternatively or additionally, the difference in weight of the concrete granulate 2 before gassing and the CO2-enriched concrete granulate 2 after gassing can also be determined. A scale 22 can be arranged on the container 4 for measuring the weight or the weight difference.

[0042] FIG. 2 shows a schematic view of a second version of a system 1 according to the disclosure for processing concrete granulate 2. The system 1 also comprises a storage tank 3 for storing a gas comprising CO2 and an at least partially gas-tight container 4. In the embodiment shown, the container 4 is open at the top and comprises an upper opening 19 for filling concrete granulate 2. A lower opening 20 for extracting the concrete granulate is arranged in a first direction opposite the upper opening 19 (direction of gravity). The lower opening 20 is shown closed in a gas-tight manner. A circular side wall of the container is arranged between the upper and lower openings 19, 20. Advantageously, the circular side-wall is also gas-tight. The circular side wall can be round or angular in cross-section. After filling with concrete granulate 2, the inlet valve 7 is opened and the container 4 is filled from bottom to top with gas comprising CO2. For this purpose, a pump 17 is arranged in the supply line 6 in the case shown. However, other arrangements are also conceivable. For a quick supply of gas, the container 4 advantageously comprises circularly arranged gas inlet nozzles 15. These can be arranged in the receiving space for the concrete granulate 2 of the container 4 and be connected to one another by lines or surround the receiving space of the container. In the case shown, two circularly arranged groups of gas inlet nozzles 15 are arranged one above the other in the first direction. At least one CO2 concentration sensor 8 may be arranged in the container 4. Advantageously, however, several CO2 concentration sensors 8 are arranged distributed in the first direction, each of which is operatively connected to a control unit 11. Alternatively or in addition, other sensors such as sensors for measuring temperature, pressure or relative humidity are also possible. The CO2 concentration sensors 8 advantageously continuously measure the CO2 concentration in the container 4. The control unit 11 controls the gas supply depending on a certain measure of the occurred CO2 absorption by the concrete granulate 2. The measure of the occurred CO2 absorption is determined by the control unit 11 via the measurements of the sensor(s) 8, as described in connection with the method above. The measure of the occurred CO2 absorption that has taken place can be the difference between the CO2 fed into the container 4 and the measured CO2 present in the container 4. Depending on the amount of CO2 already absorbed, gas comprising CO2 can be added to container 4. This ensures efficient and uniform saturation of the concrete granulate 2 in the container 4. The CO2 concentration sensor 8, which is uppermost in the direction of gravity, can be used to ensure that a predefined filling level 16 of gas in the container 4 is not exceeded. This can prevent gas from leaking from the top opening 19. Furthermore, the method can be controlled in such a way that there is always a sufficiently thick layer of uncarbonated or only partially carbonated concrete granulate 2 on the surface (facing the first opening 19) in the container 4. This layer can be used as a filter layer to absorb unwanted rising CO2. When the CO2-enriched concrete granulate 2 is extracted from the container 4 through the lower opening 20, this layer sinks to the bottom and can, for example when refilling further concrete granulate 2 from above, be provided with a predefined CO2 saturation accordingly when the method is carried out repeatedly.