Multiphase micro-nano-scale carbon dioxide dispersion loading system and concrete preparation method

Abstract

The invention relates to the technical field of concrete preparation, and provides a multiphase micro-nano-scale carbon dioxide dispersion loading system and a concrete preparation method.The system comprises a low-temperature storage tank, a supply system, a refrigerating system and a spraying system, the low-temperature storage tank comprises an inner container and a shell, a containing cavity is limited in the inner container, and a cooling cavity is limited between the inner container and the shell; the supply system is used for supplying liquid carbon dioxide to the accommodating cavity; the refrigerating system is used for supplying coolants to the cooling cavity; the spraying system comprises a spraying pipeline, a nozzle, a first control valve and a spraying temperature sensor, the spraying pipeline is communicated with the containing cavity, the nozzle is connected with the spraying pipeline and the concrete mixer, the first control valve controls the carbon dioxide flow of the spraying pipeline, and the spraying temperature sensor detects the temperature of CO2 in the spraying pipeline. According to the present invention, under the existing concrete production process control condition, the efficient reaction of the multi-phase micro-nano-scale CO2 and the concrete can be promoted, the high-performance carbon fixation concrete can be produced, and the engineering application performance and the green low-carbon property of the concrete can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete preparation, and particularly to a multiphase micro-nano scale carbon dioxide dispersion and loading system and a concrete preparation method. Background Art

[0002] With the continuous acceleration of the global industrialization process, the emissions of greenhouse gases mainly composed of carbon dioxide have increased rapidly. Among them, building materials represented by cement concrete have generated a huge amount of carbon emissions. During the concrete production process, more than 90% of the overall carbon emissions come from the raw materials brought in, and among them, the carbon emissions brought in by cement account for more than 80%.

[0003] To achieve reasonable and effective carbon reduction measures, the carbon dioxide mineralization utilization technology has been proposed in related technologies. This technology is one of the most potential and feasible technical ways for the cement concrete industry to achieve carbon emission reduction and has become a key path for the low-carbon development of the building materials industry. Since the alkaline minerals mainly composed of calcium and magnesium in cement-based binders have excellent high carbonation reaction activity and generate stable carbonate substances after reacting with carbon dioxide mineralization, the application performance of cement concrete materials can be effectively improved.

[0004] One of the main research trends in carbon dioxide mineralized cement concrete technology is to carry out mineralization curing after the cement concrete is formed, replacing the traditional standard curing or steam curing method, so as to improve the strength of cement concrete products in the short term and shorten the curing cycle. However, this technology is mainly used in the curing process of cement concrete products and requires a dedicated mineralization curing kettle, and its application scale is relatively limited.

[0005] In recent years, Canadian researchers MONKMANS. etc. directly added carbon dioxide during the mixing process of raw materials for preparing ready-mixed concrete and verified the feasibility of improving the performance of concrete and reducing the carbon footprint. Thus, it can be seen that concrete mainly based on cement-based materials can absorb and solidify a large amount of carbon dioxide during the mixing and preparation process, and this method has practical scale operability. This process integrates carbon dioxide with the cement concrete production process, and the high-purity carbon dioxide formed by capturing the carbon dioxide tail gas emitted from cement plants, steel plants, coal-fired power plants, etc. can be directly injected into fresh cement, mortar, and concrete. This process is green and pollution-free, realizing the cyclic and stable, safe solidification and utilization of carbon dioxide, and is a new, efficient, thorough, and environmentally friendly carbon sequestration method.

[0006] However, in the industrial implementation of the above carbon sequestration technology, industrial carbon dioxide injection equipment suitable for the actual production and operation of cement mortar and concrete, while ensuring excellent construction performance, mechanical properties, and durability of concrete materials, is a realistic demand in this technical field.

[0007] In the prior art, most carbon dioxide filling equipment has complex technological processes and operations, and additional intermediate stirring, sealed stirring, enhanced stirring equipment, humidification mixing equipment, etc. are required. Basically, they are all in the research and development stage of laboratory small-scale equipment and cannot be directly grafted and used with the existing concrete production equipment system of the mixing plant. Moreover, the concrete produced by the existing mixing plant is mostly high-fluidity concrete because it mostly needs to meet the requirements of construction pumping at a certain height. The fluidity of the concrete produced by the existing carbon dioxide filling equipment patents still cannot meet the existing construction pumping requirements. Therefore, it is necessary to develop a carbon dioxide dispersion and loading equipment system that can match the existing production process of the mixing plant and is efficient to achieve the mixing and mineralization treatment of cement concrete. Summary of the Invention

[0008] The present invention provides a multiphase micro-nano scale carbon dioxide dispersion and loading system and a concrete preparation method to solve the above technical defects in the prior art, and can promote the efficient reaction of carbon dioxide and concrete under the control conditions of the existing concrete production process, produce high-performance low-carbon concrete, and improve the engineering application performance and green low-carbon attributes of the concrete.

[0009] The first aspect of the present invention provides a multiphase micro-nano scale carbon dioxide dispersion and loading system, including: A cryogenic storage tank, including an inner tank and an outer shell. An accommodation cavity is defined inside the inner tank for storing cryogenic liquid carbon dioxide, and a cooling cavity is defined between the inner tank and the outer shell for accommodating a coolant; A supply system, communicating with the accommodation cavity for supplying liquid carbon dioxide to the accommodation cavity; A refrigeration system, communicating with the cooling cavity for supplying a coolant to the cooling cavity to cool the liquid carbon dioxide in the accommodation cavity to a preset temperature; An ejection system, including: An ejection pipeline, one end of which communicates with the accommodation cavity of the cryogenic storage tank; A nozzle, used to connect to a concrete mixer. The nozzle has a spraying channel, a first spraying section and a second spraying section. One end of the spraying channel communicates with the other end of the ejection pipeline. The first spraying section is connected to the spraying channel, and the second spraying section is connected to the first spraying section. The inner walls of the first spraying section and the second spraying section are both inclined surfaces, and the inclination angle of the second spraying section is greater than that of the first spraying section; A first control valve, provided in the ejection pipeline for controlling the flow rate of carbon dioxide in the ejection pipeline. The caliber of the first control valve is 0.5 mm to 2.0 mm; An ejection temperature sensor, provided in the ejection pipeline for detecting the temperature of carbon dioxide in the ejection pipeline.

[0010] The multiphase micro-nano scale carbon dioxide dispersion and loading system provided by the present invention sets the cryogenic storage tank to have a receiving cavity and a cooling cavity, enables the supply system to supply liquid carbon dioxide to the receiving cavity, and enables the refrigeration system to supply coolant to the cooling cavity. By means of temperature reduction, the control of the orifice diameter of the first control valve, and the structural setting of the nozzle, the ejection of snowflake-shaped micro-nano scale carbon dioxide in a gas-solid mixed state can be achieved. In the aspect of adding carbon dioxide during the concrete mixing process, achieving a balance between the carbon sequestration efficiency of carbon dioxide and the construction application performance of concrete is the key.

[0011] Experimental studies have shown that if only gaseous carbon dioxide is introduced, it can indeed accelerate the cement hydration reaction and improve the compressive strength of concrete to a certain extent. However, due to the limitations of its state, the addition amount of gaseous carbon dioxide per unit time is small, and under the existing concrete production process conditions, the contact time between gaseous carbon dioxide and the cement concrete slurry is short. If a high carbon sequestration amount of carbon dioxide is to be achieved, the mixing time must be extended, which will obviously have a significant impact on the production hourly efficiency of concrete. Therefore, controlling the dispersion of carbon dioxide gas and the gas flow rate is the key. If only solid carbon dioxide dry ice is added, although its addition amount can be increased, and due to the gradual sublimation process of solid carbon dioxide, its contact time with the concrete slurry is extended, which improves the carbon sequestration efficiency to a certain extent. However, the low temperature of dry ice will inhibit the hydration reaction of cement in concrete, and when the dry ice particle size is large, large pores will be left in the concrete slurry through sublimation gasification, resulting in a significant increase in the pores of hardened concrete and a decrease in mechanical strength. At this time, controlling the dispersion and the fineness of dry ice particles becomes the key.

[0012] Therefore, in the embodiment of the present invention, by cooling and refrigerating liquid carbon dioxide, combined with the control of the orifice diameter of a specific solenoid valve and the design of different inclined horn-shaped nozzles, the ejection of snowflake-shaped micro-nano scale carbon dioxide in a gas-solid mixed state is achieved. The ejection rate of the gas-solid mixed state carbon dioxide in the multiphase micro-nano scale carbon dioxide dispersion and loading system is fast, the dispersion is good, and the solid carbon dioxide particles reach an extremely fine micro-nano size, so that under the existing concrete production process control conditions of a mixing plant, it can promote the efficient reaction of carbon dioxide and concrete, produce high-performance low-carbon concrete, taking into account both the carbon sequestration efficiency of carbon dioxide and the construction application performance of concrete production, and having significant dual benefits.

[0013] The second aspect of the present invention provides a concrete preparation method, which adds the multiphase micro-nano scale carbon dioxide loaded by any one of the multiphase micro-nano scale carbon dioxide dispersion and loading systems during the mixing stage of concrete raw materials, and includes the following steps: When it is determined that the nozzle in the multiphase micro-nano scale carbon dioxide dispersion and loading system is at a preset distance from the upper middle part or below the observation port of the concrete mixer, connect the corresponding circuit facilities; Turn on the multiphase micro-nano scale carbon dioxide dispersion and loading system, check the initial status of the system's temperature, pressure, and flow rate displays, and start the refrigeration system for refrigeration; When the temperature of the liquid carbon dioxide in the accommodation chamber of the low-temperature storage tank reaches -20~-56°C, control the refrigeration system to stop refrigeration; in the case of determining that the refrigeration system has stopped refrigeration, control the low-temperature storage tank to turn on the temperature control and heat preservation mode; Set the total volume / mass of liquid carbon dioxide required for the mixer to produce a single batch of concrete, the single opening time and closing time of the liquid spraying solenoid valve in the signal monitoring and control system operation interface; The concrete mixer starts concrete production: After adding water to the raw materials and mixing for 10 - 20 s, turn off the dust collection and start injecting the carbon dioxide loaded by the multiphase micro-nano scale carbon dioxide dispersion and loading system. The injection duration of the carbon dioxide is 20 - 40 s. While injecting the carbon dioxide, the mixer keeps stirring continuously. After reaching the set injection volume, stop the injection. Subsequently, the mixer continues to stir for 20 - 30 s. Immediately after the stirring ends, discharge the concrete into the concrete truck; When it is determined that the concrete mixer produces continuously for multiple batches, clear the injection volume value of the previous batch in advance each time, and then repeat the above process.

[0014] The concrete preparation method provided by the present invention can promote the efficient reaction of carbon dioxide with concrete under the existing concrete production process control conditions, produce high-performance low-carbon concrete, and improve the engineering application performance and green low-carbon attributes of the concrete. Brief Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 is a schematic diagram of the multiphase micro-nano scale carbon dioxide dispersion and loading system provided by an embodiment of the present invention.

[0017] Figure 2 is a schematic diagram of the structure of the nozzle in the multiphase micro-nano scale carbon dioxide dispersion and loading system provided by an embodiment of the present invention.

[0018] Figure 3 is a schematic diagram of the signal detection and control system of the multiphase micro-nano scale carbon dioxide dispersion and loading system provided by an embodiment of the present invention.

[0019] Figure 4It is the installation position diagram of the nozzle of the multiphase micro-nano scale carbon dioxide dispersion and loading system provided by the embodiment of the present invention on a twin-shaft forced concrete mixer.

[0020] Figure 5 It is the state diagram of carbon dioxide ejected when the multiphase micro-nano scale carbon dioxide dispersion and loading system provided by the embodiment of the present invention is installed on a concrete mixer.

[0021] Reference numerals: 10. Low-temperature storage tank; 11. Inner tank; 12. Outer shell; 13. Accommodation cavity; 14. Cooling cavity; 15. Storage tank temperature sensor; 20. Supply system; 21. First storage tank; 22. Supply pipeline; 23. First pressure gauge; 24. Second control valve; 25. Flowmeter; 30. Refrigeration system; 31. Second storage tank; 32. Refrigeration pipeline; 33. Second pressure gauge; 34. Refrigeration solenoid valve; 35. Refrigeration temperature sensor; 40. Ejection system; 41. Ejection pipeline; 411. First sub-ejection pipeline; 412. Second sub-ejection pipeline; 413. Adapter; 42. Nozzle; 421. Spraying channel; 422. First spray port section; 423. Second spray port section; 43. First control valve; 44. Ejection temperature sensor; 45. Bypass branch; 46. Bypass control valve; 50. Concrete mixer. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0023] In the description of the embodiments of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0024] In the embodiments of the present application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0025] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0026] Figure 1 is a schematic diagram of a multiphase micro-nano scale carbon dioxide dispersion and loading system provided by an embodiment of the present invention. Figure 2 is a schematic structural diagram of a nozzle in a multiphase micro-nano scale carbon dioxide dispersion and loading system provided by an embodiment of the present invention.

[0027] Refer to Figure 1 and Figure 2 As shown in FIGS. and, an embodiment of the present invention provides a multiphase micro-nano scale carbon dioxide dispersion and loading system, which includes a cryogenic storage tank 10, a supply system 20, a refrigeration system 30, and an ejection system 40.

[0028] The cryogenic storage tank 10 includes an inner tank 11 and an outer shell 12. An accommodation cavity 13 is defined inside the inner tank 11 for storing cryogenic liquid carbon dioxide. A cooling cavity 14 is defined between the inner tank 11 and the outer shell 12 for accommodating a coolant.

[0029] Wherein, both the inner tank 11 and the outer shell 12 can be made of stainless steel material, having good low-temperature resistance and corrosion resistance, and being able to withstand a certain pressure. The accommodation cavity 13 inside the inner tank 11 can store a sufficient amount of cryogenic liquid carbon dioxide. The cooling cavity 14 is defined between the outer shell 12 and the inner tank 11 by means of welded sealing.

[0030] In addition, a heat-insulating material with good heat-insulating performance can be wrapped around the outer side of the outer shell 12, which can effectively reduce the heat exchange between the liquid carbon dioxide in the accommodation chamber 13 and the external environment, ensuring that the liquid carbon dioxide can be maintained at a low temperature state.

[0031] The supply system 20 is communicated with the accommodation chamber 13 for supplying liquid carbon dioxide to the accommodation chamber 13. Among them, the supply system 20 is connected to a liquid carbon dioxide storage tank, and the storage tank is connected to the accommodation chamber 13 of the low-temperature storage tank 10 through a pipeline.

[0032] In order to ensure that the liquid carbon dioxide can smoothly enter the accommodation chamber 13, a booster pump can also be provided in the supply system 20. The booster pump can raise the pressure of the liquid carbon dioxide to a level sufficient to overcome the pipeline resistance and the pressure in the accommodation chamber 13.

[0033] The refrigeration system 30 is communicated with the cooling chamber 14 for supplying a coolant to the cooling chamber 14 to cool the liquid carbon dioxide in the accommodation chamber 13 to a preset temperature.

[0034] Among them, the refrigeration system 30 can select carbon dioxide (CO2) as the coolant, and can also select ammonia (NH3) as the coolant. Ammonia has good refrigeration performance, with a low evaporation temperature and high refrigeration efficiency. The refrigeration system 30 includes a compressor, a condenser and an evaporator. The compressor compresses ammonia gas into a high-temperature and high-pressure gas, and then the heat is dissipated through the condenser to liquefy the ammonia. The liquefied ammonia enters the evaporator communicated with the cooling chamber 14 of the low-temperature storage tank 10 through a throttle valve. In the evaporator, the ammonia evaporates and absorbs heat, thereby cooling the liquid carbon dioxide in the accommodation chamber 13 to a preset temperature.

[0035] The ejection system 40 is communicated with the accommodation chamber 13 for ejecting the cooled liquid carbon dioxide in the accommodation chamber 13.

[0036] Among them, the ejection system 40 includes an ejection pipeline 41, a nozzle 42, a first control valve 43 and an ejection temperature sensor 44. One end of the ejection pipeline 41 is communicated with the accommodation chamber 13 of the low-temperature storage tank 10; the nozzle 42 is used to connect to a concrete mixer. The nozzle 42 has a spraying channel 421, a first spraying section 422 and a second spraying section 423. One end of the spraying channel 421 is communicated with the other end of the ejection pipeline 41. The first spraying section 422 is connected to the spraying channel 421, and the second spraying section 423 is connected to the first spraying section 422. The inner walls of the first spraying section 422 and the second spraying section 423 are both inclined planes, and the inclination angle of the second spraying section 423 is greater than that of the first spraying section 422.

[0037] The inner wall slope angle of the first nozzle section 422 is designed to be 65°, and its length is 5 cm. The inner wall slope angle of the second nozzle section 423 is designed to be 120°. This structural design helps carbon dioxide to form a suitable spraying angle and flow rate when it is ejected.

[0038] The first control valve 43 is arranged on the ejection pipeline 41 to control the flow rate of carbon dioxide in the ejection pipeline 41. The caliber of the first control valve 43 is 0.5 mm to 2.0 mm. This caliber can meet different requirements for the carbon dioxide flow rate during the concrete mixing process. The first control valve 43 adopts an electric control valve and can accurately adjust the flow rate according to the instructions of the control system.

[0039] The ejection temperature sensor 44 is arranged on the ejection pipeline 41 to detect the temperature of carbon dioxide in the ejection pipeline 41.

[0040] The carbon dioxide flowing out of the low-temperature storage tank 10 passes through the ejection pipeline 41 and enters the nozzle 42 at a suitable flow rate under the flow rate adjustment of the first control valve 43. Inside the nozzle 42, the carbon dioxide first passes through the first nozzle section 422, and due to the guidance of the inner wall slope, the flow rate and spraying angle of the carbon dioxide begin to change. Then the carbon dioxide enters the second nozzle section 423. Due to the larger inclination angle of the second nozzle section 423, the carbon dioxide is further accelerated and the spraying direction is adjusted. Finally, it is sprayed into the concrete mixer at a suitable speed and angle, and is fully mixed with the concrete raw materials to achieve the purpose of reducing the alkalinity of the concrete.

[0041] During the ejection process, the ejection temperature sensor 44 monitors the temperature of the ejection pipeline 41 in real time. If the temperature exceeds the expected range, the control system will adjust the opening degree of the refrigeration solenoid valve according to the feedback signal of the temperature sensor. For example, if the temperature is too high, it may be due to poor heat insulation effect or too large flow rate. The control system will reduce the opening degree of the refrigeration solenoid valve, reduce the flow rate, and extend the residence time of the liquid carbon dioxide in the ejection pipeline 41, thereby reducing the temperature.

[0042] According to the process requirements in the concrete mixing tank, such as different concrete mix ratios or mixing speeds, the control system can accurately adjust the opening degree of the refrigeration solenoid valve, thereby controlling the ejection flow rate of the liquid carbon dioxide. For example, when it is necessary to improve the carbon sequestration efficiency of the concrete, the opening degree of the refrigeration solenoid valve can be appropriately increased to increase the ejection flow rate of the liquid carbon dioxide, but at the same time, it is necessary to ensure that the temperature is within a suitable range.

[0043] The multiphase micro-nano scale carbon dioxide dispersion and loading system provided by the embodiments of the present invention sets the low-temperature storage tank 10 to have a containing cavity 13 and a cooling cavity 14, enables the supply system 20 to supply liquid carbon dioxide to the containing cavity 13, and enables the refrigeration system 30 to supply a coolant to the cooling cavity 14. By means of cooling measures, the control of the caliber of the first control valve 43, and the structural setting of the nozzle 42, the ejection of snowflake-shaped micro-nano scale carbon dioxide in a gas-solid mixed state can be realized. In the aspect of the technology of adding carbon dioxide during the concrete mixing process, achieving the balance between the carbon sequestration efficiency of carbon dioxide and the construction application performance of concrete is the key.

[0044] Experimental studies have shown that if only gaseous carbon dioxide is introduced, it can indeed accelerate the cement hydration reaction and improve the compressive strength of concrete to a certain extent. However, due to the limitation of its state, the addition amount of gaseous carbon dioxide per unit time is small, and under the existing concrete production process conditions, the contact time between gaseous carbon dioxide and the cement concrete paste is short. If a high carbon sequestration amount of carbon dioxide is to be achieved, the mixing time must be extended, which will obviously have a significant impact on the production hourly efficiency of concrete. Therefore, controlling the dispersion of carbon dioxide gas and the gas flow rate is the key. If only solid carbon dioxide dry ice is added, although its addition amount can be increased, and since the solid carbon dioxide exists in a process of gradual sublimation, its contact time with the concrete paste is extended, and the carbon sequestration efficiency is improved to a certain extent. However, the too-low temperature of dry ice will inhibit the hydration reaction of cement in concrete, and when the dry ice particle size is large, large pores will be left in the concrete paste through sublimation gasification, resulting in a significant increase in the pores of the hardened concrete and a decrease in the mechanical strength. At this time, controlling the dispersion and the fineness of dry ice particles becomes the key.

[0045] Therefore, the embodiments of the present invention realize the ejection of snowflake-shaped micro-nano scale carbon dioxide in a gas-solid mixed state by cooling and refrigerating liquid carbon dioxide, combined with the control of the caliber of a specific solenoid valve and the design of different inclined-angle horn-shaped nozzles 42. The ejection rate of the gas-solid mixed state carbon dioxide in the multiphase micro-nano scale carbon dioxide dispersion and loading system is fast, the dispersion is good, and the carbon dioxide particles for carbon sequestration reach an extremely fine micro-nano size. Thus, under the existing concrete production process control conditions of a mixing plant, it can promote the efficient reaction between carbon dioxide and concrete, produce high-performance low-carbon concrete, taking into account both the carbon sequestration efficiency of carbon dioxide and the construction application performance of concrete production, and having significant dual benefits.

[0046] Continue to refer to Figure 2, the ejection pipeline 41 includes a first sub-ejection pipeline 411, a second sub-ejection pipeline 412, and a transfer pipe 413. The first sub-ejection pipeline 411 communicates with the accommodation chamber 13 of the cryogenic storage tank 10; the second sub-ejection pipeline 412 is used to connect to a concrete mixer; the transfer pipe 413 is respectively connected to the first sub-ejection pipeline 411 and the second sub-ejection pipeline 412. Among them, the ejection temperature sensor 44 is arranged on the transfer pipe 413, and the first control valve 43 is arranged on the second sub-ejection pipeline 412.

[0047] In the embodiment of the present invention, the ejection temperature sensor 44 is arranged on the transfer pipe 413, and the temperature of the carbon dioxide about to enter the concrete mixer can be detected more accurately. Because the transfer pipe 413 is the transition part of the carbon dioxide from the cryogenic storage tank 10 to the concrete mixer, detecting the temperature here can comprehensively consider the temperature change during the pipeline transmission process, providing more reliable data for subsequent control and adjustment.

[0048] The first control valve 43 is arranged on the second sub-ejection pipeline 412, making the control of the carbon dioxide flow rate flowing into the concrete mixer more direct and flexible. Compared with arranging the control valve on the first sub-ejection pipeline 411, this setting can adjust the flow rate more precisely according to the actual needs in the concrete mixer.

[0049] Continue to refer to Figure 1 , in some embodiments of the present invention, the ejection system 40 further includes a bypass branch 45 and a bypass control valve 46. The bypass branch 45 is connected to the transfer pipe 413; the bypass control valve 46 is arranged on the bypass branch 45 and is used to control the on-off of the bypass branch 45.

[0050] Equivalently, the transfer pipe 413 can be of a Y-shaped or tee structure, and the three branch channels of the transfer pipe 413 are respectively connected to the first sub-ejection pipeline 411, the second sub-ejection pipeline 412, and the transfer pipe 413.

[0051] Among them, the bypass control valve 46 can be a bypass solenoid valve. The function of the bypass solenoid valve is to consider that when supplying carbon dioxide for the first time, the temperature of the ejection pipeline 41 is relatively high (room temperature), and it is difficult to ensure the gas-solid mixed phase carbon dioxide at the nozzle 42 at the outlet end. The bypass branch 45 is designed, and by setting the bypass time and monitoring the pipeline temperature sensor, the injection into the concrete mixer is started until the temperature of the ejection pipeline 41 drops to -20~-56°C.

[0052] Equivalently, when the ejection temperature sensor 44 detects that the temperature of the ejection pipeline 41 deviates from the preset range, for example, the temperature is too high, the bypass control valve 46 is controlled to open. At this time, a part of the liquid carbon dioxide will be shunted through the bypass branch 45, thereby changing the flow rate and flow velocity of the liquid carbon dioxide in the ejection pipeline 41.

[0053] Due to the flow - splitting effect of the bypass branch 45, the residence time of the liquid carbon dioxide in the ejection pipeline 41 will change, thereby affecting its temperature. According to the feedback of the ejection temperature sensor 44, the opening degree of the bypass control valve 46 can be gradually adjusted until the temperature of the ejection pipeline 41 is restored to the preset range.

[0054] In addition, during system maintenance or testing, the bypass control valve 46 can be used to isolate a part of the ejection pipeline 41. For example, when it is necessary to repair the part of the ejection pipeline 41 after the ejection temperature sensor 44, the refrigeration solenoid valve before the bypass branch 45 can be closed, and the bypass control valve 46 can be opened to guide the liquid carbon dioxide to the bypass branch 45, so as to safely perform maintenance or testing work on the ejection pipeline 41.

[0055] In the embodiment of the present invention, the setting of the bypass branch 45 and the bypass control valve 46 provides an additional means for the temperature regulation of the ejection system 40. When the flow rate cannot be quickly and effectively controlled by the refrigeration solenoid valve to keep the temperature of the ejection pipeline 41 within a suitable range, the flow - splitting effect of the bypass branch 45 can more flexibly adjust the temperature, improving the temperature control ability of the entire system, ensuring that the liquid carbon dioxide is ejected at a suitable temperature, which is beneficial to improving the carbon sequestration efficiency and construction application performance of concrete.

[0056] During system maintenance and testing, the presence of the bypass control valve 46 and the bypass branch 45 can conveniently isolate specific areas of the ejection pipeline 41, reducing the difficulty of maintenance and testing, improving work efficiency, and at the same time reducing the impact on the operation of the entire system, ensuring the safety and reliability of the system.

[0057] Continue to refer to Figure 1 , in some embodiments of the present invention, the supply system 20 includes a first storage tank 21, a supply pipeline 22, a first pressure gauge 23, and a second control valve 24.

[0058] The first storage tank 21 is used to store liquid carbon dioxide, and the volume of the storage tank can store a sufficient amount of liquid carbon dioxide. A safety valve is provided at the top of the storage tank to ensure the safety of the storage tank.

[0059] One end of the supply pipeline 22 is connected to the first storage tank 21, and the other end is connected to the accommodation chamber 13 of the cryogenic storage tank 10. At the connection points of the supply pipeline 22 with the first storage tank 21 and the cryogenic storage tank 10, flange connections with good sealing performance are used, and low - temperature - resistant sealing gaskets are used to ensure that there is no leakage at the connection points.

[0060] The first pressure gauge 23 is provided on the supply pipeline 22 and is used to detect the pressure of the supply pipeline 22. The first pressure gauge 23 is a high - precision digital pressure gauge.

[0061] The second control valve 24 is provided in the supply pipeline 22 to control the flow rate and on / off of carbon dioxide in the supply pipeline 22. The second control valve 24 can be an electric control valve, and its caliber matches the diameter of the supply pipeline 22.

[0062] When it is necessary to supply liquid carbon dioxide to the accommodation chamber 13 of the cryogenic storage tank 10, the control system reads the pressure value of the first pressure gauge 23 according to a preset program or a user's instruction. If the pressure value is within the normal range, the control system sends an opening signal to the second control valve 24 to gradually open the valve.

[0063] As the opening degree of the second control valve 24 increases, liquid carbon dioxide flows from the first storage tank 21 along the supply pipeline 22 to the accommodation chamber 13 of the cryogenic storage tank 10. During this process, the first pressure gauge 23 monitors the pressure of the supply pipeline 22 in real time. If the pressure shows abnormal fluctuations (such as a sudden increase or decrease), the control system adjusts the opening degree of the second control valve 24 according to the pressure change to keep the pressure in the supply pipeline 22 stable.

[0064] In the embodiment of the present invention, the flow rate of liquid carbon dioxide is accurately controlled by the second control valve 24, and an appropriate amount of liquid carbon dioxide can be accurately supplied according to the requirements of the accommodation chamber 13 of the cryogenic storage tank 10. For example, the flow rate can be adjusted to meet the supply amount of liquid carbon dioxide in different production stages or different process requirements. At the same time, the real-time monitoring of the pressure by the first pressure gauge 23 and the regulation of the pressure fluctuation by the second control valve 24 ensure the stability of the pressure in the supply pipeline 22, avoiding pipeline damage caused by excessive pressure or affecting the supply efficiency of liquid carbon dioxide due to too low pressure.

[0065] Refer to Figure 2 , in some embodiments of the present invention, the refrigeration system 30 further includes a flow meter 25. The flow meter 25 is provided in the supply pipeline 22 to measure the flow rate of the supply pipeline 22.

[0066] Among them, the measurement range of the flow meter 25 is 0.1~50L / H.

[0067] Continue to refer to Figure 2 , in some embodiments of the present invention, the refrigeration system 30 includes a second storage tank 31, a refrigeration pipeline 32, a second pressure gauge 33, and a refrigeration solenoid valve.

[0068] The second storage tank 31 is used to store liquid carbon dioxide. One end of the refrigeration pipeline 32 is connected to the second storage tank 31, and the other end is connected to the cooling chamber 14 of the cryogenic storage tank 10. The connection parts of the refrigeration pipeline 32 with the second storage tank 31 and the cooling chamber 14 of the cryogenic storage tank 10 adopt a combination of welding and flange connection.

[0069] The second pressure gauge 33 is provided on the refrigeration pipeline 32 and is used to detect the pressure of the refrigeration pipeline 32. The second pressure gauge 33 is a digital pressure gauge. The refrigeration solenoid valve is provided on the refrigeration pipeline 32 and is used to control the on-off of the refrigeration pipeline 32.

[0070] The control system can remotely control the refrigeration solenoid valve through a PLC (Programmable Logic Controller), or manual operation can be performed on the local control panel.

[0071] Before the system starts, liquid carbon dioxide has been stored in the second storage tank 31. The operator checks whether the connection of the refrigeration pipeline 32 is firm, and whether the second pressure gauge 33 and the refrigeration solenoid valve are in normal states. The initial flow rate and pressure parameters of the refrigeration pipeline 32 are set through the control system.

[0072] When the system starts, the control system sends an opening signal to the refrigeration solenoid valve, and the valve gradually opens. Liquid carbon dioxide flows from the second storage tank 31 along the refrigeration pipeline 32 to the cooling chamber 14 of the low-temperature storage tank 10. During this process, the second pressure gauge 33 monitors the pressure of the refrigeration pipeline 32 in real time.

[0073] According to the cooling capacity requirement of the cooling chamber 14 of the low-temperature storage tank 10, the control system adjusts the opening degree of the refrigeration solenoid valve based on the pressure signal feedback by the second pressure gauge 33 and the preset pressure-flow relationship curve, so as to accurately control the flow rate of liquid carbon dioxide. For example, if the cooling chamber 14 requires more cooling capacity, the control system will increase the opening degree of the refrigeration solenoid valve to increase the flow rate of liquid carbon dioxide.

[0074] During the operation of the refrigeration system 30, the second pressure gauge 33 continuously monitors the pressure, and the temperature sensor monitors the temperature of the liquid carbon dioxide. If abnormal pressure fluctuations occur, such as too high pressure, the control system will immediately reduce the opening degree of the refrigeration solenoid valve to reduce the flow rate to avoid pipeline damage. When the cooling chamber 14 of the low-temperature storage tank 10 reaches the required cooling effect or the system needs to stop running, the control system sends a closing signal to the refrigeration solenoid valve, and the valve gradually closes to stop the supply of liquid carbon dioxide.

[0075] Through the precise control of the flow rate of the refrigeration pipeline 32 by the refrigeration solenoid valve in the embodiment of the present invention, the required cooling capacity can be accurately provided according to the actual demand of the cooling chamber 14 of the low-temperature storage tank 10. The real-time pressure monitoring and feedback of the second pressure gauge 33 enable the control system to adjust the flow rate in a timely manner according to the pressure change, ensuring the stability and accuracy of the refrigeration process. This helps to cool the liquid carbon dioxide in the accommodation chamber 13 of the low-temperature storage tank 10 to the precise preset temperature, improving the operation efficiency of the entire system.

[0076] It should be noted that, in order to save system costs, the first storage tank 21 and the second storage tank 31 can share a storage tank, that is, the same storage tank uses an independent dual pipeline supply. One pipeline directly transports liquid carbon dioxide to the supply system 20, and the other pipeline transports it to the refrigeration system 30. The liquid carbon dioxide is used as a coolant to cool the carbon dioxide in the low-temperature storage tank 10.

[0077] In the embodiment of the present invention, pressurized normal-temperature liquid carbon dioxide is cooled to -20~-56°C and then suddenly depressurized and the flow rate is controlled to achieve carbon dioxide phase separation. Part of it gasifies into gas, and part of it cools down to become solid dry ice. In addition, compared with Freon and ammonia refrigeration, carbon dioxide is a green, safe, reliable and highly efficient refrigerant. The ozone depletion potential of carbon dioxide is 0, and the global warming potential is 1, which means it has no destructive effect on the atmospheric ozone layer and can effectively reduce the global greenhouse effect; carbon dioxide has a wide source and low price, which can greatly reduce the refrigerant replacement cost and achieve the goals of energy conservation, emission reduction and environmental protection; at the same time, it also has excellent thermal stability and will not decompose harmful gases even in a high-temperature environment, and the operation is safe and harmless.

[0078] Continue to refer to Figure 2 , in some embodiments of the present invention, the refrigeration system 30 further includes a refrigeration temperature sensor 35. The refrigeration temperature sensor 35 is arranged in the cooling chamber 14 and is used to detect the temperature of the cooling chamber 14.

[0079] In some embodiments of the present invention, the purity of the liquid carbon dioxide provided by the supply system 20 is greater than or equal to 99.5%. It can be commercially available liquid carbon dioxide or liquid carbon dioxide obtained by carbon capture and purification from industrial emission sources.

[0080] The source of the liquid carbon dioxide in the supply system 20 is specialized chemical production enterprises, and these enterprises adopt advanced production processes. During the production process, first, the raw material gas (such as carbon dioxide in combustion exhaust gas) is strictly pretreated. For example, through processes such as desulfurization and denitrification, impurity gases such as sulfur dioxide and nitric oxide are removed. Through multiple evaporation and condensation processes, carbon dioxide is separated from other impurities (such as methane, oxygen, etc.), so as to ensure that the purity of the liquid carbon dioxide is greater than or equal to 99.5%.

[0081] High-purity liquid carbon dioxide (purity greater than or equal to 99.5%) can ensure that in processes such as concrete mixing, the reaction between carbon dioxide and other substances is more stable and predictable. For example, in the process of carbon sequestration in concrete, carbon dioxide with fewer impurities can react more effectively with components such as cement, improve the carbon sequestration efficiency, and reduce the reaction anomalies or quality instability caused by impurities.

[0082] Low-purity carbon dioxide may contain impurities such as acidic gases, which can corrode components such as pipelines, valves, and storage tanks of equipment. High-purity liquid carbon dioxide can reduce this corrosion, extend the service life of equipment, and lower equipment maintenance costs.

[0083] The temperature range of the liquid carbon dioxide provided by the supply system 20 and the refrigeration system 30 is 0~30°C, and the pressure range is 2.0~7.0 Mpa.

[0084] The first storage tank 21 can be equipped with a temperature control system. When the temperature of the liquid carbon dioxide is lower than 0°C or higher than 30°C, the temperature controller will automatically adjust the heating or cooling device of the storage tank. The heating device uses an electric heating wire with a power of 5-10 kW, which can quickly increase the temperature of the liquid carbon dioxide; the cooling device uses an air-cooled heat exchanger, which can effectively reduce the temperature of the liquid carbon dioxide.

[0085] For pressure control, a pressure regulating valve is installed on the first storage tank 21. When the pressure is lower than 2.0 MPa, the pressure regulating valve will automatically open to supplement gaseous carbon dioxide from the outside to maintain the pressure; when the pressure is higher than 7.0 MPa, the safety valve will automatically open to release the excess gas to ensure that the pressure is within the range of 2.0~7.0 MPa.

[0086] In the supply pipeline 22, the first pressure gauge 23 monitors the pressure in real time, and the second control valve 24 adjusts the flow rate according to the pressure feedback signal. If the pressure is too high, the second control valve 24 will reduce the opening degree, and vice versa, to keep the pressure stable.

[0087] The second storage tank 31 also adopts a similar temperature control system, and its cooling device uses a liquid ammonia refrigeration system 30. Liquid ammonia evaporates and absorbs heat in the evaporator to control the temperature of the liquid carbon dioxide within the range of 0~30°C.

[0088] In the refrigeration pipeline 32, the second pressure gauge 33 monitors the pressure, and the refrigeration solenoid valve adjusts the flow rate. When the liquid carbon dioxide flows from the second storage tank 31 to the cooling chamber 14 of the low-temperature storage tank 10, according to the demand of the cooling chamber 14, the flow rate is controlled by adjusting the opening degree of the refrigeration solenoid valve, and then the pressure is controlled within the range of 2.0~7.0 MPa.

[0089] The temperature range of the low-temperature liquid carbon dioxide stored in the low-temperature storage tank 10 is -20~-56°C, and the pressure range is 0.2~7.0 Mpa.

[0090] Inside the cryogenic storage tank 10, temperature sensors and pressure sensors are installed to monitor the temperature and pressure in real time. When the temperature is higher than -56°C, the refrigeration system 30 will increase the refrigeration capacity and transfer more liquid carbon dioxide from the second storage tank 31 to the cooling chamber 14 of the cryogenic storage tank 10; when the temperature is lower than -20°C, the refrigeration system 30 will reduce the refrigeration capacity or stop refrigerating.

[0091] For pressure control, when the pressure is lower than 0.2 MPa, liquid carbon dioxide will be supplemented from the supply system 20; when the pressure is higher than 7.0 MPa, the safety valve will automatically open to release the excess pressure.

[0092] When it is necessary to take out liquid carbon dioxide from the cryogenic storage tank 10 for other processes (such as the spraying system 40), according to the set pressure and temperature ranges, after the control system ensures that the temperature and pressure inside the storage tank meet the requirements, the liquid carbon dioxide will be transported to the next stage.

[0093] In the supply system 20 and the refrigeration system 30, controlling the temperature of the liquid carbon dioxide within the range of 0 - 30°C and the pressure within the range of 2.0 - 7.0 MPa can ensure the stable transmission of the liquid carbon dioxide in the pipeline. Under suitable temperature and pressure conditions, the physical properties of the liquid carbon dioxide are relatively stable, and the fluid resistance is small, which is beneficial to improving the overall operating efficiency of the system.

[0094] In the cryogenic storage tank 10, controlling the temperature within the range of -20~-56°C and the pressure within the range of 0.2~7.0 MPa can ensure the safety and stability of the liquid carbon dioxide during storage. For example, within this temperature and pressure range, it can prevent problems such as the liquid carbon dioxide vaporizing due to too high a temperature, resulting in a sharp increase in pressure, or the damage of the storage tank structure due to too low a temperature.

[0095] Precise temperature and pressure control enables the liquid carbon dioxide to meet different process requirements. For example, during the concrete mixing process, different mixing speeds, concrete ratios, and other factors may have different requirements for the temperature and pressure of the liquid carbon dioxide. Through precise control of the temperature and pressure, the state of the liquid carbon dioxide can be adjusted according to specific process requirements, thereby better meeting the production needs and improving the product quality.

[0096] The multiphase micro-nano scale carbon dioxide dispersion and loading equipment system provided by the embodiments of the present invention can be directly connected to the existing concrete mixer in the mixing plant flexibly and conveniently. The nozzle can be installed by drilling holes in the upper middle part of the concrete mixer and then used. The application is simple and there is no need to transform the existing production process and equipment. During the concrete mixing and preparation process, highly dispersed carbon dioxide in multiphase micro-nano scale can be accurately injected. The injection path of the gas-solid mixed state micro-nano scale carbon dioxide can be intelligently regulated, and the customized design and control of parameters such as the carbon dioxide injection volume, injection interval time, and injection duration can be realized. The system pressure and the temperature at the nozzle outlet are monitored in real time and dynamically, and the accurate and automatic control of the carbon dioxide injection volume and the start and stop of injection can be realized. It has a high degree of automation, simple operation, convenient use, high production efficiency, and is easy to move and graft with the existing production equipment system. It effectively solves the problems of poor dispersion effect, low carbon fixation efficiency, incomplete carbon fixation of the current carbon dioxide injection system, mismatch with the existing concrete production process and system in the mixing plant, and insignificant improvement in the strength and durability of cement concrete.

[0097] The carbonated ready-mixed concrete produced by the present invention has good workability and construction pumping performance. There is no need to change the existing concrete mix ratio in the mixing plant, no need to add extra water or any admixture, and the cement consumption can be reduced, thus lowering the production cost of concrete. The concrete has high mechanical strength, good durability, and good carbon fixation effect. While realizing the permanent sequestration and solidification of carbon dioxide, the mechanical strength and durability of the concrete are improved. This technology has strong applicability and can be directly promoted and used, making cement, mortar, and concrete more carbon-neutral.

[0098] Adding an appropriate amount of multiphase micro-nano scale carbon dioxide to the present invention will not affect the fluidity and construction performance of the concrete mixture. It is consistent with the existing concrete production process in the mixing plant. The carbon dioxide dispersion and loading control system is easy to connect with the central control system of the existing concrete mixing plant. The process flow is simple, the equipment investment and operation cost are low, and the production energy consumption is low. The integrated control of carbonated concrete production is realized, with simple and convenient operation, and it can flexibly adapt to the concrete production of different grades of products in the mixing plant, realizing the carbon fixation utilization of carbon dioxide and the optimization of the strength performance of concrete, making it more carbon-neutral.

[0099] The device system can be directly connected to the existing cementitious material slurry and the concrete mixer in the mixing station. During the preparation process of concrete mixing, it can accurately inject carbon dioxide with a highly dispersed multi-phase micro-nano scale, and can regulate the gas-solid mixed state micro-nano scale carbon dioxide injection path, realizing the customized design and control of parameters such as carbon dioxide injection volume, injection interval time, and injection duration. The system pressure and the temperature at the spray outlet are monitored in real time and dynamically, and it can accurately and automatically control the injection volume and start / stop of carbon dioxide injection. The operation is simple and convenient, effectively solving the problems of poor dispersion effect, low carbon sequestration efficiency, incomplete carbon sequestration in the current carbon dioxide injection system, incompatibility with the existing concrete production process and system in the mixing station, and insignificant improvement in the strength and durability of cement concrete. The present invention contributes to the resource utilization of carbon dioxide in building materials, can be flexibly and conveniently directly connected to the existing concrete production process system in the mixing station, realizes the permanent sequestration and solidification of carbon dioxide while improving the mechanical strength and durability of concrete, and promotes the green and low-carbon transformation and development of the building materials industry.

[0100] Figure 3 It is a schematic diagram of the signal detection and control system of the multi-phase micro-nano scale carbon dioxide dispersion and loading system provided by the embodiment of the present invention. Figure 4 It is a diagram showing the installation position of the nozzle 42 of the multi-phase micro-nano scale carbon dioxide dispersion and loading system provided by the embodiment of the present invention on a twin-shaft forced concrete mixer. Figure 5 It is a diagram showing the state of carbon dioxide ejected when the multi-phase micro-nano scale carbon dioxide dispersion and loading system provided by the embodiment of the present invention is installed on a concrete mixer.

[0101] Refer to Figures 3 to 5 , the present invention also provides a concrete preparation method, in which multi-phase micro-nano scale carbon dioxide is added during the raw material mixing stage in the concrete production process. The main steps are as follows: S100: Install the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system at a suitable position beside the concrete mixer in the mixing station. The nozzle 42 is installed in the upper middle part or at a short distance below the observation port of the twin-shaft forced concrete mixer, and the circuit facilities are connected.

[0102] S200: Turn on the power of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system, check the initial state of all temperature and pressure displays of the equipment system, and start the liquid carbon dioxide refrigeration.

[0103] S300: When the temperature of carbon dioxide in the low-temperature liquid carbon dioxide storage tank of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system reaches -20~-56°C, stop refrigeration automatically and turn on temperature control and heat preservation. S400: Set and input the total volume / mass of liquid carbon dioxide required for a single batch of concrete production by the mixer and the single injection time interval of the nozzle 42 in the operation interface of the signal monitoring and control system. S500: The concrete production control system in the central control room of the mixing plant starts to initiate the production of a single batch of concrete. After all raw materials (PO cement, admixture, sand and gravel aggregate, admixture) are mixed with water for 10 - 20 s, the injection of carbon dioxide is started, and a set amount of carbon dioxide is injected (for a duration of 20 - 40 s). While injecting carbon dioxide, the mixer keeps continuously stirring. After reaching the set injection amount, the injection automatically stops, and then the mixer continues to stir for 20 - 30 s. Immediately after the stirring ends, the concrete is discharged into the concrete mixer truck; preferably, after all raw materials of the concrete are mixed with water for 10 - 20 s and the initial state of the slurry is stirred out, then carbon dioxide is introduced, and the mineralization effect is more sufficient. At this time, the cement-based binder has undergone a certain degree of pre-hydration, and the dissolved calcium ions are available for the dissolution of multi-phase carbon dioxide to participate in the mineralization reaction, improving the reaction efficiency and the carbon sequestration effect of carbon dioxide; S600: When the mixing plant conducts continuous multi-batch production, the injection amount of the previous batch is cleared in advance each time, and then the process of S500 is repeated.

[0104] The present invention also provides a method for preparing concrete. According to the different grades and products of the produced concrete, the total mass of carbon dioxide injection is 0.01 - 2.0% of the mass of cement in the concrete raw material system, preferably within 0.5%.

[0105] Preferably, the total mass of carbon dioxide injection is within 0.5% of the mass of cement in the concrete raw material system. This is because when the injection amount is ≥0.5%, it will significantly affect the workability of the produced concrete out of the machine, significantly reducing the slump and spread of the concrete. When the concrete is transported to the construction site by the concrete mixer truck, with the extension of the transportation waiting time, the workability loss of the concrete with a high amount of carbon dioxide added is obvious. Under the condition that no additional water and admixture are allowed, it is easy to cause pumping pipe blockage and pump blockage, and it is impossible to carry out pumping construction, not meeting the performance requirements of the existing ready-mixed concrete. When the addition amount of multi-phase micro-nano scale carbon dioxide in the gas-solid phase is controlled within 0.5% of the mass of cement, it has little impact on the workability of the concrete out of the machine and the workability loss over time, and can ensure the construction pumping requirements within 2 h when the concrete is transported to the construction site by the mixer truck. The slump of the concrete during pumping can still be guaranteed to be above 180 mm, and the performance of the hardened concrete is excellent, meeting the construction application requirements of the existing ready-mixed concrete.

[0106] The method for preparing concrete provided by the present invention is not limited to being applied in the production of concrete, and can also be applied in the mixing preparation process of cement-based material neat paste, mortar, and slurry containing calcium and magnesium alkaline solid waste. During the mixing process, multi-phase micro-nano scale carbon dioxide is injected, and the addition time and the total amount of carbon dioxide added are flexibly adjusted according to actual needs and the performance of the fresh slurry product.

[0107] In the following examples, concrete raw materials are directly produced using a mixing plant, including PO42.5 cement, Class II fly ash, S95 slag powder, sand (medium sand), gravel (5 - 25 mm), admixture, and water. The corresponding examples and comparative examples are produced successively for different batches of concrete on the same day, and both use raw materials from exactly the same batch.

[0108] Example 1: This example provides an application method of a multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system in concrete production, including: S100. Install the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system at a safe position beside the concrete mixer of the mixing plant. Install the nozzle 42 below the observation port of the concrete twin-shaft compulsory mixer, and connect the circuit facilities. S200. Turn on the power of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system, check the initial state of all signal displays such as temperature and pressure of the equipment system, set the target refrigeration temperature to -40°C, and start the liquid carbon dioxide refrigeration. S300. When the temperature of carbon dioxide in the low-temperature liquid carbon dioxide storage tank of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system reaches -40°C, automatically stop refrigeration and turn on temperature control and heat preservation. S400. The central control room of the mixing plant determines the concrete grade and mix ratio. The mix ratio per cubic meter of C30 concrete: 194 kg of PO42.5 cement, 64 kg of Class II fly ash, 109 kg of S95 slag powder, 911 kg of medium sand, 1134 kg of gravel, 5.8 kg of admixture, and 170 kg of water.

[0109] S500. Set and input in the operation interface of the signal monitoring and control system the total volume of liquid carbon dioxide to be added as 705 ml when the mixer produces a single batch of 2 m3 of concrete, the mass of carbon dioxide added accounts for 0.2% of the mass of cement, the single opening time of the liquid injection solenoid valve is 20 s, and the closing time is 0.

[0110] S600. The concrete production control system in the central control room of the mixing plant starts to produce a single batch of concrete. After all raw materials (PO cement, admixture, sand and gravel aggregate, admixture) are mixed and water is added for 15 s, turn off the dust collection and start to inject carbon dioxide. The injection is completed within 20 - 30 s. The mixer keeps continuously stirring while injecting carbon dioxide. After reaching the set injection volume of 705 ml, automatically stop injection. Subsequently, the mixer continues to stir for 30 s. Immediately unload the concrete into the concrete truck after the stirring ends. When the S700 mixer plant produces continuously for 7 batches with each mixer truck, before each batch starts, clear the actual filling volume value of the previous batch in advance on the operation interface of the signal monitoring and control system, and then repeat the process of S600. The ready-mixed concrete is transported to the construction site for construction, and test blocks with dimensions of 10mm×10mm×10mm are formed and their performance is tested after standard curing.

[0111] Comparative Example 1: The concrete raw materials and mix ratios are exactly the same as those in Example 1. It is produced according to the normal production process of the mixer plant without adding carbon dioxide. Similarly, the mixed concrete is formed and its performance is tested, and then transported to the same construction site for construction by mixer trucks.

[0112] Example 2: This example provides an application method of a multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system in concrete production, including: S100. Install the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system at a safe position beside the concrete mixer of the mixer plant. Install the nozzle 42 below the observation port of the concrete twin-shaft compulsory mixer, and connect the circuit facilities. S200. Turn on the power of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system, check the initial state of all signal displays such as temperature and pressure of the equipment system, set the target refrigeration temperature to -40°C, and start the liquid carbon dioxide refrigeration. S300. When the temperature of carbon dioxide in the low-temperature liquid carbon dioxide storage tank of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system reaches -40°C, automatically stop refrigeration and turn on the temperature control and heat preservation. S400. The central control room of the mixer plant determines the concrete grade and mix ratio. The mix ratio per cubic meter of C30 concrete is: 200 kg of PO42.5 cement, 47 kg of Class II fly ash, 105 kg of S95 slag powder, 868 kg of medium sand, 1172 kg of crushed stone, 4.3 kg of admixture, and 175 kg of water.

[0113] S500. Set and input on the operation interface of the signal monitoring and control system the total volume of liquid carbon dioxide to be filled required for the mixer to produce 2 m³ of concrete per batch as 1090 ml, the mass of carbon dioxide added accounting for 0.3% of the mass of cement, the single opening time of the liquid injection solenoid valve as 20 s, and the closing time as 0.

[0114] The S600, the concrete production control system in the central control room of the mixing plant, starts to produce a single batch of concrete. After all raw materials (PO cement, admixture, sand and gravel aggregate, admixture) are mixed and water is added for 15 s, the dust collection is turned off and the injection of carbon dioxide is started. The injection is completed within 30 - 40 s. While injecting carbon dioxide, the mixer keeps stirring continuously. After reaching the set injection volume of 1090 ml, the injection automatically stops, and the mixer continues to stir for 25 s. Immediately after the stirring ends, the concrete is discharged into the concrete truck. S700. When each truck in the mixing plant produces 7 consecutive batches, before each batch starts, the actual injection volume value of the previous batch is cleared in advance on the operation interface of the signal monitoring and control system, and then the process of S600 is repeated. The whole truck of concrete is transported to the construction site for construction, and test blocks of 10 mm × 10 mm × 10 mm are formed and the performance is tested after standard curing.

[0115] Comparative Example 2: The concrete raw materials and mix ratio are exactly the same as those in Example 2. It is produced according to the normal production process of the mixing plant without adding carbon dioxide. Similarly, the produced concrete is formed and its performance is tested, and it is transported to the same construction site for construction by the truck.

[0116] Example 3: This example provides an application method of a multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system in concrete production, including: S100. Install the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system at a safe position beside the concrete mixer in the mixing plant. The nozzle 42 is installed below the observation port of the concrete double-horizontal shaft forced mixer, and the circuit facilities are connected. S200. Turn on the power of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system, check the initial state of all signals such as temperature and pressure of the equipment system, set the target refrigeration temperature to -45 °C, and start the liquid carbon dioxide refrigeration. S300. When the temperature of carbon dioxide in the low-temperature liquid carbon dioxide storage tank of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system reaches -45 °C, the refrigeration automatically stops and the temperature control and heat preservation are turned on. S400. The central control room of the mixing plant determines the concrete grade and mix ratio. The single-side mix ratio of C40 concrete: 272 kg of PO42.5 cement, 60 kg of grade II fly ash, 129 kg of S95 slag powder, 783 kg of medium sand, 1175 kg of crushed stone, 7.4 kg of admixture, and 170 kg of water.

[0117] S500. Set the total volume of liquid carbon dioxide to be injected, which is 988 ml, when the mixer produces a single batch of 2 m3 of concrete, the mass of carbon dioxide added accounts for 0.2% of the mass of cement, the single opening time of the liquid injection solenoid valve is 20 s, and the closing time is 0 on the operation interface of the signal monitoring and control system.

[0118] In S600, the concrete production control system in the central control room of the mixing plant starts to produce a single batch of concrete. After all raw materials (PO cement, admixture, sand and gravel aggregate, admixture) are mixed and water is added for 15 s, the dust collection is turned off and carbon dioxide injection is started. The injection is completed within 20 - 30 s. While injecting carbon dioxide, the mixer keeps stirring continuously. When the set injection volume of 988 ml is reached, the injection automatically stops, and then the mixer continues to stir for 30 s. After the stirring is completed, the concrete is immediately discharged into the concrete mixer truck. In S700, when each mixer truck in the mixing plant produces 7 consecutive batches, before each batch starts, the actual injection volume value of the previous batch is cleared in advance on the operation interface of the signal monitoring and control system, and then the process of S600 is repeated. The whole truck of concrete is transported to the construction site for construction, and test blocks of 10 mm × 10 mm × 10 mm are formed and their performance is tested after standard curing.

[0119] Comparative Example 3: The concrete raw materials and mix ratio are exactly the same as those in Example 3. It is produced according to the normal production process of the mixing plant without adding carbon dioxide. Similarly, the concrete discharged from the mixer is formed and its performance is tested, and it is transported to the same construction site for construction by the mixer truck.

[0120] Example 4: This example provides an application method of a multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system in concrete production, including: In S100, the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system is installed at a safe position beside the concrete mixer in the mixing plant. The nozzle 42 is installed below the observation port of the concrete twin-shaft compulsory mixer, and the circuit facilities are connected. In S200, the power supply of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system is turned on, and the initial states of all signals such as temperature and pressure of the equipment system are checked. The target refrigeration temperature is set to -40 °C, and the liquid carbon dioxide refrigeration is started. In S300, when the temperature of carbon dioxide in the low-temperature liquid carbon dioxide storage tank of the multi-phase micro-nano scale carbon dioxide dispersion and loading equipment system reaches -40 °C, the refrigeration automatically stops and the temperature control and heat preservation are turned on. In S400, the central control room of the mixing plant determines the concrete grade and mix ratio. The mix ratio per cubic meter of C30 concrete is: 204 kg of PO42.5 cement, 47 kg of Class II fly ash, 105 kg of S95 slag powder, 868 kg of medium sand, 1134 kg of crushed stone, 5.7 kg of admixture, and 170 kg of water.

[0121] S500. Set the total volume of liquid carbon dioxide to be added as 1482 ml, the mass of carbon dioxide added to account for 0.4% of the mass of cement, the single opening time of the liquid spraying solenoid valve as 20 s, and the closing time as 0 when producing a single batch of 2 m³ concrete in the signal monitoring and control system operation interface.

[0122] S600. The concrete production control system in the central control room of the mixing plant starts to produce a single batch of concrete. After mixing all raw materials (PO cement, admixture, sand and gravel aggregate, admixture) with water for 15 s, the dust collection is turned off and the carbon dioxide injection is started. The injection is completed within 30 - 40 s. The mixer keeps continuously stirring while injecting carbon dioxide. After reaching the set injection volume of 1482 ml, the injection automatically stops, and then the mixer continues to stir for 30 s. Immediately after the stirring ends, the concrete is discharged into the concrete truck. S700. When each truck of the mixing plant continuously produces 7 batches, before each batch starts, clear the actual injection volume value of the previous batch in advance in the signal monitoring and control system operation interface, and then repeat the process of S600. The whole truck of concrete is transported to the construction site for construction, and test blocks with dimensions of 10 mm × 10 mm × 10 mm are formed and tested for performance after standard curing.

[0123] Comparative Example 4: The concrete raw materials and mix ratio are exactly the same as those in Example 4. It is produced according to the normal production process of the mixing plant without adding carbon dioxide. Similarly, the concrete discharged from the mixer is formed and tested for performance, and is transported to the same construction site for construction by the concrete truck.

[0124] The performance test results of the concrete produced in all the above examples and comparative examples are shown in Table 1.

[0125] Table 1. Various performances of the concrete produced in all examples and comparative examples

[0126] As can be seen from Table 1, compared with the ordinary concrete of the control sample, the workability of the C30 and C40 ready-mixed concrete produced by applying the multi-phase micro-nano scale carbon dioxide dispersion loading equipment system reaches over 180 mm in slump both at the time of discharge from the mixer and after being transported by the tanker to the construction site for 0.5 h - 1.5 h, and the construction pumping performance is good. The compressive strength of the concrete with multi-phase micro-nano scale carbon dioxide added within 0.5% of the cement mass is higher than that of the ordinary concrete from 3 d to 56 d, all meeting the design strength requirements, and the 28-day compressive strength improvement rate is between 10.3% and 15.6%; moreover, the carbonation depth of the concrete with multi-phase micro-nano scale carbon dioxide added is smaller and the chloride ion migration coefficient is lower than that of the ordinary concrete under the same conditions, indicating that the concrete with this carbon dioxide added has more excellent carbonation resistance and chloride ion penetration resistance, and better durability. By testing and calculating the carbon sequestration amount of the carbon dioxide concrete produced on the production line of the mixing plant, it is obtained that the carbon sequestration amount of the C30 concrete reaches 405 g / m 3 or more, and the carbon sequestration amount of the C40 concrete reaches 510 g / m 3 or more, with excellent carbon sequestration performance.

[0127] Generally speaking, the multi-phase micro-nano scale carbon dioxide dispersion loading equipment system invented in this patent can be directly connected to the existing concrete mixer of the mixing plant flexibly and conveniently without modifying the existing production process equipment. During the concrete mixing and preparation process, it can accurately inject multi-phase micro-nano scale highly dispersed carbon dioxide, with high automation and simple operation. The carbon sequestration concrete produced by applying this multi-phase micro-nano scale carbon dioxide dispersion loading equipment system has good workability and construction pumping performance, high mechanical strength, good durability, and good carbon sequestration effect, realizing the permanent sequestration and solidification of carbon dioxide while improving the mechanical strength and durability of the concrete. This technology can also increase the carbon sink income of cement concrete enterprises when entering the carbon market in the future, enhance the low-carbon market competitiveness, and has significant economic, social and ecological environmental benefits.

[0128] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multiphase micro-nano scale carbon dioxide dispersion and loading system, characterized in that Comprising: A cryogenic storage tank (10), including an inner tank (11) and an outer shell (12), an accommodation cavity (13) is defined inside the inner tank (11), the accommodation cavity (13) is used for storing cryogenic liquid carbon dioxide, a cooling cavity (14) is defined between the inner tank (11) and the outer shell (12), and the cooling cavity (14) is used for accommodating a coolant; A supply system (20), communicating with the accommodation cavity (13), for supplying liquid carbon dioxide to the accommodation cavity (13); A refrigeration system (30), communicating with the cooling cavity (14), for supplying a coolant to the cooling cavity (14) to cool the liquid carbon dioxide in the accommodation cavity (13) to a preset temperature; An ejection system (40), including: An ejection pipeline (41), one end of which communicates with the accommodation cavity (13) of the cryogenic storage tank (10); A nozzle (42), for connecting to a concrete mixer (50), the nozzle (42) has an ejection channel (421), a first ejection port section (422) and a second ejection port section (423), one end of the ejection channel (421) communicates with the other end of the ejection pipeline (41), the first ejection port section (422) is connected to the ejection channel (421), the second ejection port section (423) is connected to the first ejection port section (422), the inner walls of the first ejection port section (422) and the second ejection port section (423) are both inclined surfaces, and the inclination angle of the second ejection port section (423) is greater than the inclination angle of the first ejection port section (422); A first control valve (43), provided on the ejection pipeline (41), for controlling the flow rate of carbon dioxide in the ejection pipeline (41), and the caliber of the first control valve (43) is 0.5 mm to 2.0 mm; An ejection temperature sensor (44), provided on the ejection pipeline (41), for detecting the temperature of carbon dioxide in the ejection pipeline (41).

2. The multiphase micro-nano scale carbon dioxide dispersion and loading system according to claim 1, characterized in that, The ejection pipeline (41) includes: A first sub-ejection pipeline (411), communicating with the accommodation cavity (13) of the cryogenic storage tank (10); A second sub-ejection pipeline (412), for connecting to the concrete mixer (50); An adapter pipe (413), respectively connected to the first sub-ejection pipeline (411) and the second sub-ejection pipeline (412); Wherein, the ejection temperature sensor (44) is provided on the adapter pipe (413), and the first control valve (43) is provided on the second sub-ejection pipeline (412).

3. The multiphase micro-nano scale carbon dioxide dispersion and loading system according to claim 2, characterized in that The ejection system (40) further includes: A bypass branch (45), connected to the adapter pipe (413); A bypass control valve (46), provided on the bypass branch (45), for controlling the on-off of the bypass branch (45).

4. The multiphase micro-nano scale carbon dioxide dispersion and loading system according to claim 1, characterized in that, The supply system (20) includes: A first storage tank (21), for storing liquid carbon dioxide; A supply pipeline (22), one end of which communicates with the first storage tank (21), and the other end communicates with the accommodation cavity (13) of the cryogenic storage tank (10); A first pressure gauge (23), provided on the supply pipeline (22), for detecting the pressure of the supply pipeline (22). A second control valve (24) is provided in the supply pipeline (22) for controlling the flow rate of carbon dioxide in the supply pipeline (22).

5. The multiphase micro-nano scale carbon dioxide dispersion and loading system according to claim 4, wherein The supply system (20) further includes: A flow meter (25) is provided in the supply pipeline (22) for measuring the flow rate of carbon dioxide in the supply pipeline (22).

6. The multiphase micro-nano scale carbon dioxide dispersion and loading system according to claim 1, characterized in that The refrigeration system (30) includes: A second storage tank (31) for storing liquid carbon dioxide; A refrigeration pipeline (32) with one end communicating with the second storage tank (31) and the other end communicating with the cooling chamber (14) of the low-temperature storage tank (10); A second pressure gauge (33) is provided in the refrigeration pipeline (32) for detecting the pressure in the refrigeration pipeline (32); A refrigeration solenoid valve (34) is provided in the refrigeration pipeline (32) for controlling the on / off of the refrigeration pipeline (32).

7. The multiphase micro-nano scale carbon dioxide dispersion and loading system according to claim 6, characterized in that, The refrigeration system (30) further includes: A refrigeration temperature sensor (35) is provided in the cooling chamber (14) for detecting the temperature of the coolant in the cooling chamber (14).

8. The multiphase micro-nano scale carbon dioxide dispersion loading system according to any one of claims 1 to 7, characterized in that The purity of the liquid carbon dioxide provided by the supply system (20) is greater than or equal to 99.5%; The temperature range of the liquid carbon dioxide provided by the supply system (20) and the refrigeration system (30) is 0~30°C, and the pressure range is 2.0~7.0 Mpa; The temperature range of the low-temperature liquid carbon dioxide stored in the accommodation chamber (13) of the low-temperature storage tank (10) is -20~-56°C, and the pressure range is 0.2~7.0 Mpa.

9. A method for preparing concrete, characterized in that, Adding the multiphase micro-nano scale carbon dioxide loaded by the multiphase micro-nano scale carbon dioxide dispersion loading system according to any one of claims 1 to 8 during the mixing stage of concrete raw materials includes the following steps: When it is determined that the nozzle (42) in the multiphase micro-nano scale carbon dioxide dispersion loading system is at a preset distance from the upper middle part or below the observation port of the concrete mixer (50), connect the corresponding circuit facilities; Control the multiphase micro-nano scale carbon dioxide dispersion loading system to start, check the initial state of the temperature, pressure, and flow rate display of the system, and start the refrigeration system (30) for refrigeration; When the temperature of the liquid carbon dioxide in the accommodation chamber (13) of the low-temperature storage tank (10) reaches -20~-56°C, control the refrigeration system (30) to stop refrigeration; in the case of determining that the refrigeration system (30) stops refrigeration, control the low-temperature storage tank (10) to turn on the temperature control and heat preservation mode; Set the total volume / mass of liquid carbon dioxide to be filled and the opening and closing times of the liquid spraying solenoid valve each time when the concrete mixer produces a single batch of concrete on the operation interface of the signal monitoring and control system; The concrete mixer (50) starts concrete production: After adding water to the raw materials and mixing for 10 - 20 s, the dust collection is turned off and carbon dioxide loaded by the multiphase micro-nano scale carbon dioxide dispersion and loading system is started to be injected. The injection duration of carbon dioxide is 20 - 40 s. While injecting carbon dioxide, the mixer keeps continuously mixing. After reaching the set injection amount, the injection stops, and then the mixer continues to mix for 20 - 30 s. Immediately after mixing ends, the concrete is discharged into the concrete tanker truck; When it is determined that the concrete mixer (50) conducts continuous multi-batch production, the injection amount value of the previous batch is cleared in advance each time, and then the above process is repeated.

10. The concrete preparation method according to claim 9, wherein, The total mass of carbon dioxide injection is 0.01% - 2.0% of the mass of cement in the concrete raw material system.

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