Tower reaction device, calcium carbonate preparation system and method

Abstract

The present application discloses a tower reaction device, a calcium carbonate preparation system and method, the calcium carbonate preparation system includes a tower reaction device and a solid-liquid separation device, the tower reaction device includes a first reaction unit and a second reaction unit located below it, both reaction units are provided with a distributor for providing a first material, the top of the tower reaction device is provided with a first feed inlet and a gas outlet for providing a second material, the first material and the second material react in the tower reaction device, the first reaction unit has an overflow trough, and the side wall opposite to the overflow trough and the bottom of the second reaction unit are provided with a first discharge port connected to the solid-liquid separation device, the solid-liquid separation device performs solid-liquid separation on the material of the first discharge port, obtains calcium carbonate solid, and at the same time circulates part of the unreacted second material, so that the second material is more fully utilized. The present application makes the material more evenly distributed in the reaction device, the residence time is controllable, and the uniformity of the calcium carbonate particle size is improved.

Description

Technical Field

[0001] The present invention relates to the field of chemical technology, and more specifically, to a tower reaction device, a calcium carbonate preparation system and a method. Background Art

[0002] Industrial preparation of calcium carbonate is usually done by precipitation in the liquid phase. Calcium carbonate is an important inorganic chemical raw material, widely used in rubber, plastics, papermaking, ink, coatings, medicine, textiles and many other fields. The preparation methods of calcium carbonate are mainly carbonization and double decomposition, in addition to sol-gel method, microemulsion method, etc. Carbonization is the core process of light calcium carbonate production. Its main process is: through the reaction of carbon dioxide-containing gas with calcium hydroxide slurry, or with calcium and alkaline solution, calcium carbonate is generated and precipitated from the liquid phase.

[0003] The particle size and morphology of calcium carbonate directly determine its performance and application. The reactor and reaction process will affect the particle size and morphology of calcium carbonate. At present, the more mature carbonization processes mainly include intermittent / continuous bubbling carbonization, multi-stage spray carbonization and ultra-gravity carbonization. Among them, ultra-gravity carbonization is suitable for the preparation of nano-scale calcium carbonate, while for micron-scale calcium carbonate, the bubbling method is mostly used. The intermittent bubbling carbonization method generally adopts a low-temperature stirring bubbling carbonization reactor. Calcium oxide or calcium hydroxide slurry is added to the carbonization tower, and then carbon dioxide is introduced. The calcium carbonate product is obtained by carbonization to the end point. Some processes will add an appropriate amount of morphology control agent in time. This method is characterized by simple operation and low equipment investment, but discontinuous production, low degree of automation, unsatisfactory gas-liquid mass transfer, long carbonization time, serious backmixing, wide product particle size distribution, large differences between different batches of products, and poor reproducibility. The continuous bubbling carbonization method generally adopts two-stage or three-stage series carbonization. The lime milk is partially carbonized in the first-stage carbonization tower, and then added with appropriate additives in the slurry tank and then enters the second-stage carbonization tower for carbonization to obtain the calcium carbonate product. This method can obtain better crystal shape and smaller particle size distribution by graded control of nucleation and growth processes. However, this process requires multiple carbonization reactors, graded control of carbonization rate, and complex process routes and equipment.

[0004] It is expected that the equipment and processes will be further improved, equipment investment and process complexity will be reduced, production energy consumption will be reduced, the uniformity of the particle size of calcium carbonate products will be controlled, and product consistency and stability will be improved. Summary of the invention

[0005] The object of the present invention is to provide a tower reaction device, a calcium carbonate preparation system and a method, so that the material is distributed more evenly in the reaction device, the absorption efficiency of carbon dioxide is improved, and the particle size of the calcium carbonate product is effectively controlled, the carbon dioxide content range of the applicable gas is increased, and the consistency and stability of the product are improved.

[0006] According to one aspect of the present invention, a tower reaction device is provided, comprising: a first reaction unit, the first reaction unit having a first flow guide, an overflow groove formed between the first flow guide and the side wall of the first reaction unit; a second reaction unit, located below the first reaction unit and connected to the first reaction unit; wherein the first reaction unit and the second reaction unit are both provided with distributors to provide a first material to the tower reaction device, and a first feed inlet and a gas outlet are also provided on the top of the tower reaction device, the first feed inlet is used to provide a second material to the tower reaction device, the first material and the second material react in the tower reaction device, and a first discharge port is provided at the side wall of the first reaction unit opposite to the overflow groove and at the bottom of the second reaction unit.

[0007] Preferably, the first reaction units include a plurality of first reaction units, which are connected in sequence from top to bottom, and the first reaction unit at the bottom is connected to the second reaction unit.

[0008] Preferably, the first reaction unit further comprises a sieve plate, the sieve plate is located at the bottom of the first reaction unit, the sieve plate has sieve holes, and the first flow guide and the distributor in the first reaction unit are both located above the sieve plate.

[0009] Preferably, the opening rate of the sieve plate is 20% to 40%.

[0010] Preferably, the first flow guide is cylindrical, coaxial with the side wall of the first reaction unit, the distributor is located inside the first flow guide, and the bottom of the first flow guide is connected to the side wall of the first reaction unit outside the first flow guide.

[0011] Preferably, a ratio of a diameter of the first flow guide to that of the first reaction unit is 0.7:1 to 0.85:1, and a ratio of a height of the first flow guide to that of the first reaction unit is 0.4:1 to 0.8:1.

[0012] Preferably, the second reaction unit has a second flow guide, which is cylindrical and has a size corresponding to that of the first flow guide. The diameter of the second flow guide gradually decreases at its bottom and corresponds to the first discharge port.

[0013] Preferably, the ratio of the height to the diameter of the first reaction unit is 1:1 to 4:1.

[0014] Preferably, the device further comprises a conduit, one end of which is connected to the first feed port, and the other end of which extends to the axis of the tower reaction device, so that the second material is input from the top axis of the tower reaction device.

[0015] According to another aspect of the present invention, a calcium carbonate preparation system is also provided, comprising: a tower reaction device as described in any of the above items; a solid-liquid separation device, comprising a second feed inlet, and a first feed outlet of the tower reaction device is connected to the second feed inlet of the solid-liquid separation device to provide part of the material in the tower reaction device to the solid-liquid separation device; wherein the first feed inlet is used to provide calcium-containing carbonized liquid into the tower reaction device, the distributor is used to provide gas containing carbon dioxide into the tower reaction device, and the solid-liquid separation device is used to perform solid-liquid separation on the material provided by the first feed outlet to obtain calcium carbonate solid.

[0016] Preferably, the solid-liquid separation device comprises at least one of a sedimentation tank, a filter or a centrifuge.

[0017] Preferably, the solid-liquid separation device is a sedimentation tank, and a second discharge port is provided at the bottom of the sedimentation tank to discharge calcium carbonate precipitate; the upper side wall of the sedimentation tank is also provided with a third discharge port, and the third discharge port is connected to the first feed port of the tower reaction device to provide at least part of the clear liquid in the sedimentation tank together with fresh calcium-containing carbonized liquid to the tower reaction device.

[0018] Preferably, the system further comprises: a drying device, which is connected to the second discharge port of the solid-liquid separation device and is used for drying the calcium carbonate precipitate.

[0019] According to another aspect of the present invention, a method for preparing calcium carbonate is also provided, which uses the calcium carbonate preparation system as described above, and the method comprises: passing a calcium-containing carbonized liquid into the tower reaction device; passing a gas containing carbon dioxide into the tower reaction device; passing a first product from the first discharge port into the solid-liquid separation device; and drying the solid product obtained from the solid-liquid separation device to obtain a calcium carbonate product.

[0020] Preferably, the method further comprises: introducing at least a portion of the clear liquid separated from the solid-liquid separation device into the tower reaction device together with fresh calcium-containing carbonized liquid to further improve the utilization rate of calcium in the calcium-containing mineralized liquid.

[0021] Preferably, the method further comprises: mixing carbide slag with ammonium chloride to obtain alkaline calcium-containing carbonized liquid.

[0022] Preferably, the calcium-containing carbonized liquid comprises at least one of calcium hydroxide slurry and calcium chloride ammonia solution, and the mass fraction of calcium in the calcium-containing carbonized liquid is 6% to 18%.

[0023] Preferably, the gas containing carbon dioxide comprises at least one of waste gas from thermal power plants, waste gas from coal chemical industry and waste gas from cement plants, and the mass fraction of carbon dioxide in the gas containing carbon dioxide is 5% to 90%.

[0024] Preferably, the superficial gas velocity of the carbon dioxide-containing gas provided by the distributor is 0.2-2 cm / s, and the ratio of the molar flow rate of calcium in the calcium-containing carbonized liquid to the molar flow rate of carbon dioxide in the carbon dioxide-containing gas is 1:1.1 to 1:1.5.

[0025] Preferably, the volume flow ratio of the clear liquid at least partially separated from the solid-liquid separation device to the fresh calcium-containing carbonized liquid is 2:1 to 5:1.

[0026] The tower reaction device, calcium carbonate preparation system and method provided by the embodiment of the present invention, the tower reaction device is divided into a plurality of reaction units in the tower by a sieve plate, and a distributor is arranged in each reaction unit to realize multi-point uniform gas distribution and multi-stage continuous carbonization, so that the gas containing carbon dioxide is uniformly distributed in the tower, and the absorption efficiency of carbon dioxide is effectively improved. The calcium carbonate preparation system adds an overflow tank to each reaction unit in the tower reaction device, and under the synergistic effect of the external solid-liquid separation device, the residence time of the generated calcium carbonate in the tower can be effectively controlled, and the growth of calcium carbonate can be controlled to obtain fine calcium carbonate (particle size is micron-level), which solves the problems of uneven calcium carbonate products prepared by traditional bubbling carbonization and uncontrollable product particle size. Further, the preparation method of calcium carbonate provided by the present invention requires less equipment, simple process flow, and is easy to be enlarged by engineering. It not only makes the material more evenly distributed in the reaction device, improves the absorption efficiency of carbon dioxide, and achieves effective control of the particle size of the calcium carbonate product, but also increases the carbon dioxide content range of applicable gases, can treat and utilize a variety of industrial waste gases, and the final calcium carbonate product also has high consistency and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0028] Figure 1 A schematic diagram of a tower reaction device according to an embodiment of the present invention is shown;

[0029] Figure 2 A schematic diagram of a calcium carbonate preparation system according to an embodiment of the present invention is shown;

[0030] Figure 3 A schematic flow chart of a method for preparing calcium carbonate according to an embodiment of the present invention is shown;

[0031] Figure 4The electron microscope image of calcium carbonate obtained by the method for preparing calcium carbonate in the embodiment of the present invention is shown; DETAILED DESCRIPTION

[0032] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same components are represented by the same reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale. In addition, some well-known parts may not be shown.

[0033] It should be understood that when describing the structure of a component, when a unit or a region is referred to as being "on" or "above" another unit or another region, it may mean being directly above the other unit or another region, or including other units or regions between the unit or another region and the other unit or another region. Furthermore, if the component is turned over, the unit or a region will be "below" or "below" the other unit or another region.

[0034] If the purpose is to describe the situation of being directly on another unit or another area, this article will use the expression "directly on..." or "on... and adjacent to...".

[0035] Many specific details of the present invention are described below, such as component structures, materials, dimensions, processing techniques and technologies, in order to more clearly understand the present invention. However, as those skilled in the art will appreciate, the present invention may be implemented without following these specific details.

[0036] The present invention may be embodied in various forms, some examples of which will be described below.

[0037] Figure 1A schematic diagram of a tower reaction device according to an embodiment of the present invention is shown. The tower reaction device 100 has a multi-stage design, including a first reaction unit 110 and a second reaction unit 120. Specifically, the tower reaction device 100 is, for example, a three-stage design, including two first reaction units 110 and one second reaction unit 120. The three reaction units are sequentially connected from top to bottom, the second reaction unit 120 is located at the bottom, and the two connected first reaction units 110 are located above the second reaction unit 120. A distributor 130 is provided in each of the first reaction unit 110 and the second reaction unit 120. Taking the preparation of calcium carbonate using industrial waste gas containing carbon dioxide as an example, the industrial waste gas containing carbon dioxide can enter the interior of the tower reaction device 100 through the distributor 130. Specifically, the distributor 130 is disc-shaped and located on the axis of the tower reaction device 100. It faces upward along the axis of the tower reaction device 100, so that the industrial waste gas containing carbon dioxide forms an upward airflow. The top of the tower reaction device 100 is provided with a first feed inlet 140 and a gas outlet 150. Specifically, the first feed inlet 140 is, for example, located at the side of the top of the tower reaction device 100, and the gas outlet 150 is, for example, located at the top of the axis of the top of the tower reaction device 100. The first feed inlet 140 is used to provide carbonized liquid to the tower reaction device 100, and the carbonized liquid can react with industrial waste gas containing carbon dioxide to generate calcium carbonate. In order to make the carbonized liquid more evenly distributed and increase the contact area between the carbonized liquid and the industrial waste gas, a conduit 141 is also provided at the first feed inlet 140, one end of the conduit 141 is connected to the first feed inlet 140, and the other end extends to the axis of the tower reaction device 100, so that the carbonized liquid enters the interior of the tower reaction device 100 from the axis of the tower reaction device 100, and the gas outlet 150 is used to discharge the gas.The first reaction unit also includes a first guide member 111, which is, for example, cylindrical. The first guide member 111 is coaxial with the tower reaction device 100, and the first guide member 111 has an umbrella-shaped folded edge at its bottom facing outward. The first guide member 111 is connected to the side wall of the first reaction unit 110 through the folded edge, so that an overflow groove 112 with an annular gap is formed between the first guide member 111 and the side wall. A first discharge port 113 is also provided at a position on the side wall of the first reaction unit 110 corresponding to the bottom of its overflow groove 112. The upwardly rushing airflow formed by the distributor 130 reacts with the carbonized liquid flowing in from the top of the tower reaction device 100, and part of the material enters the overflow port 113. The tower reaction device is discharged through a flow channel 112 and a first discharge port 113. The material discharged from the first discharge port 113 is, for example, a mixed liquid containing solids and liquids, specifically including a post-reaction solution and part of the reaction product, calcium carbonate; further, a sieve plate 114 is also provided at the bottom of the first reaction unit 110, and sieve holes are provided on the sieve plate 114. Part of the material can enter the next reaction unit through the sieve holes on the sieve plate 114 under the action of gravity; in the first reaction unit 110, the first guide member 111, the overflow channel 112, the first discharge port 113 and the distributor 130 are all located above the sieve plate 114, and the distributor 130 is located on the inner side of the cylindrical first guide member 111. The second reaction unit 120 is, for example, located at the bottom of the tower reaction device 100. The second reaction unit 120 has a funnel-shaped bottom and is provided with a first discharge port 113 at the bottom. The second reaction unit 120 has a second guide 121. The second guide 121 corresponds to the first guide 111. The second guide 121 is, for example, also cylindrical, and its bottom also has a folded edge. The folded edge is folded inwardly so that the bottom of the second guide 121 forms a funnel shape that shrinks inwardly. The distributor 130 of the second reaction unit is located on the inner side of the second guide 121 and is slightly higher than the funnel-shaped bottom that shrinks inwardly. A guide groove 122 with an annular gap is also formed between the second guide 121 and the side wall of the second reaction unit 120. The bottom of the guide groove 122 is connected to the bottom of the second reaction unit 120.

[0038] Of course, although Figure 1 The tower reaction device 100 shown is a three-stage (three-section) design including two first reaction units 110 and one second reaction unit 120, but the tower reaction device 100 can also be changed into a two-stage design including only one first reaction unit 110 and one second reaction unit 120 or a multi-stage design with more first reaction units 110 according to specific needs, which can also achieve similar technical effects.

[0039] Specifically, taking the tower reaction device 100 as an example, the two sieve plates 114 therein divide the interior of the device into three sections (two first reaction units 110 and one second reaction unit 120), forming a multi-section reaction space, each section is provided with a distributor 130, so that the industrial waste gas containing carbon dioxide can enter from multiple points inside the reaction device, which is conducive to its uniform distribution inside the device; the first reaction unit 110 also has a first guide member 111 to form an overflow trough 112; the second reaction unit 120 also has a second guide member 121 to form a guide trough 122, and the carbonized liquid enters from the top of the tower reaction device 100. Based on the effect of gravity, the carbonized liquid also quickly flows to the bottom of the tower reaction device 100, so that the carbonized liquid cannot fully contact and react with the industrial waste gas. Through the design of the overflow trough 112 and the guide trough 122, the carbonized liquid can be partially retained in each section of the device, so that the carbonized liquid is distributed more widely and more evenly in the device.

[0040] In order to enable the tower reaction device 100 to obtain a better reaction effect, the sizes of its components also have specific size ratio requirements. Specifically, the height of each section (the distance between two adjacent sieve plates) in the tower reaction device 100 is 1 to 4 times the diameter of the tower body (the diameter of the first reaction unit). Preferably, the ratio of the distance between two adjacent sieve plates to the diameter of the first reaction unit is 2:1 to 3:1; the first flow guide 121 is cylindrical, and the ratio of its diameter to the tower body diameter is 0.7 to 0.85:1, and the ratio of its height to the distance between two adjacent sieve plates is 0.4 to 0.8:1; the porosity of the sieve plate 114 is 20% to 40%.

[0041] For a specific example, the tower body of the tower reaction device 100 has a diameter of 250 mm and a total height of 2200 mm. Its bottom (the bottom of the second reaction unit) is a 90° cone surface, and there are two sieve plates 114 inside. The distance between the sieve plate 114 near the bottom and the bottom is 800 mm, and the distance between the sieve plate 114 near the top and the sieve plate 114 near the bottom is, for example, 600 mm. The diameter of the sieve holes on the sieve plate 114 is 3 mm, and the area of ​​the sieve holes accounts for 26% of the area of ​​the sieve plate 114. The height of the first flow guide 111 is 300 mm and the diameter is 200 mm. The bottom of the first flow guide 111 is connected to the side wall of the tower body through a 60° cone surface; the height of the second flow guide 121 is 300 mm and the diameter is 200 mm. The lower end of the second flow guide 121 is closed to a diameter of 80 mm through a 90° cone surface, and there is a spacing of 25 mm between the 90° cone surface of the second flow guide 121 and the cone surface at the bottom of the tower body. The distributor 130 is, for example, a metal sintered microporous distributor with a distribution area of ​​24 cm 2The average pore size of the micropores is 20 μm. In the first reaction unit 110, the distributor 130 is located 30 mm above the sieve plate and at the device axis position. The distributor 130 in the second reaction unit 120 is located 600 mm below the sieve plate 114 of the first reaction unit 110 above it. The tower reaction device 100 has a conduit 141 at the top, and the outlet of the conduit 141 is located 600 mm above the sieve plate 114 in the top first reaction unit 110.

[0042] Figure 2 The schematic diagram of the calcium carbonate preparation system according to the embodiment of the present invention is shown; the calcium carbonate preparation system comprises a tower reaction device 100 and a solid-liquid separation device 200, the tower reaction device 100 is, for example, Figure 1 The tower reaction device shown, its specific structure is not repeated; the first discharge port 113 of the tower reaction device 100 is connected to the second feed port 210 to transfer part of the material in the tower reaction device 100 to the solid-liquid separation device 200. The solid-liquid separation device is, for example, a sedimentation tank, a filter or a centrifuge, etc., and a second discharge port 220 is provided at the bottom thereof to discharge the calcium carbonate precipitate (solid product). If the solid-liquid separation device uses a filter, its filtration area is, for example, 1 square meter, and filter pressure filtration is used.

[0043] The upper side wall of the solid-liquid separation device 200 is also provided with a third discharge port 230, and the third discharge port 230 is used to discharge the liquid product. Specifically, the liquid product is, for example, a filtered clear liquid, which contains some unreacted calcium-containing carbonized liquid. Part of the liquid product can be discharged, and part of it can be mixed with fresh calcium-containing carbonized liquid and then introduced into the tower reaction device 100 together to achieve recycling and make more effective use of the calcium-containing carbonized liquid.

[0044] Compared with the prior art, the calcium carbonate preparation system provided by the present invention mainly comprises two parts, a tower reaction device and a solid-liquid separation device. The tower reaction device is divided into a plurality of reaction units by arranging a sieve plate, so as to realize segmented gas distribution and multi-stage continuous carbonization, so that the concentration and distribution of the gas containing carbon dioxide in the device are more uniform, which is beneficial to improving the absorption efficiency of carbon dioxide. By adding an overflow tank to each reaction unit in the tower reaction device and adding a solid-liquid separation device on the outside, the residence time of the calcium carbonate generated in the device in the device can be controlled, and the growth of the calcium carbonate can be controlled to obtain fine calcium carbonate, so as to solve the problems of microscopic uneven mixing and uncontrollable product particle size of the calcium carbonate generated by the traditional bubbling carbonization method. Furthermore, the calcium carbonate preparation system can be applied to a wider range of carbon dioxide content in the gas, and its equipment and process are simple and easy to realize, and can be enlarged by engineering to realize mass production, so as to have strong practicality.

[0045] Figure 3The schematic diagram of the process for preparing calcium carbonate according to the embodiment of the present invention is shown; specifically, using Figure 2 The process of preparing calcium carbonate in the calcium carbonate preparation system shown is as follows:

[0046] In step S10, the calcium-containing carbonized liquid is introduced into the tower reaction device; fresh calcium-containing (alkaline) carbonized liquid is introduced into the reactor from the upper end of the tower reaction device through the first feed inlet, and the calcium-containing carbonized liquid flows in from top to bottom.

[0047] In step S20, the carbon dioxide-containing gas is introduced into the tower reaction device; the carbon dioxide-containing gas is introduced into the tower reaction device through the distributor in each reaction unit, so that the carbon dioxide-containing gas enters the tower reaction device from multiple points at different heights to contact and react with the calcium-containing carbonized liquid.

[0048] In step S30, the first product from the first discharge port is introduced into a solid-liquid separation device; the calcium-containing carbonized liquid reacts with the carbon dioxide-containing gas in the tower reaction device, and part of the liquid is discharged from the first discharge port at the bottom of the overflow tank through the overflow tank of the first reaction unit, and most of the liquid continues to flow to the next reaction unit through the sieve plate, until the remaining part of the liquid finally enters the second reaction unit at the bottom of the tower reaction device and is discharged from the first discharge port at the bottom of the second reaction unit; the first product discharged from the first discharge port, for example, includes at least part of the unreacted calcium-containing carbonized liquid and calcium carbonate precipitate, and the first product is introduced into a solid-liquid separation device for solid-liquid separation to obtain the calcium carbonate precipitate;

[0049] In step S40, the solid product obtained from the solid-liquid separation device is dried to obtain a calcium carbonate product. The calcium carbonate precipitate is further dehydrated and dried to obtain a final calcium carbonate product.

[0050] Of course, since the liquid portion of the first product also contains unreacted calcium-containing carbonized liquid, in order to make full use of this part of the resources, part of the liquid product obtained from the solid-liquid separation device is discharged, and the other part can be added to the tower reaction device through the first feed port for recycling. Specifically, at least part of the liquid product obtained from the solid-liquid separation device is introduced into the tower reaction device together with the fresh calcium-containing carbonized liquid.

[0051] Specifically, the gas containing carbon dioxide can be industrial waste gas such as waste gas from thermal power plants, coal chemical industry, and cement plant waste gas. The calcium-containing carbonized liquid can also be made of carbide slag, and the main elements of carbide slag include, for example, 1.03% aluminum oxide, 4.01% silicon dioxide, 0.19% iron oxide, 66.86% calcium oxide, 0.11% magnesium oxide, 26.68% loss on ignition, and 1.12% others. The carbonized liquid containing calcium chloride, ammonia, and ammonium chloride can be obtained by reacting carbide slag with ammonium chloride. The main components of the calcium-containing carbonized liquid include: 90.0g / L calcium chloride, 8.7g / L ammonium chloride, and 13.5g / L ammonia.

[0052] The above-mentioned calcium-containing carbonized liquid is introduced into the tower reaction device through the first feed port at a flow rate of 0.4L / min, and the volume of the solution is 86% of the total volume of the tower reaction device. The waste gas from the thermal power plant (the volume fraction of carbon dioxide is 15%) is introduced into the tower reaction device from three units through a distributor, and the ventilation volume of the three units is the same, for example, all are 17.65L / min (under standard conditions, the empty tower gas flow rate is 0.6cm / s); the first product is continuously discharged (extracted) from the first discharge port and sent to the solid-liquid separation device (filter) through the second feed port, and the total extraction flow rate of the first product is 1.0L / min (the extraction flow rates of the three first discharge ports are the same). Part (flow rate 0.6L / min) of the liquid product (flow rate 0.88L / min) separated by filtration is circulated to the first feed port, mixed with fresh calcium-containing carbonized liquid and then introduced into the tower reaction device. The solid product separated by filtration is then dried to obtain a calcium carbonate product. The yield of the calcium carbonate product is 1.81kg / h. In this preparation method, the conversion rate of carbon dioxide is 83.6%, and the conversion rate of calcium is 92.1%. The electron microscope image of the obtained calcium carbonate product is as follows: Figure 4 As shown, the calcium carbonate product is spherical, with a particle size of 2 μm, a whiteness of 98.5, and a purity of 98.8%.

[0053] In order to further verify the consistency and stability of the calcium carbonate product prepared by the method and to explore the scope of each component in the raw materials to which the method is applicable, the following examples are listed for illustration.

[0054] Similarly, calcium carbide slag is also used to make calcium-containing carbonized liquid, and the main components of the obtained calcium-containing carbonized liquid include: 120.0g / L calcium chloride, 11.6g / L ammonium chloride, and 18.0g / L ammonia. The flow rate of the fresh calcium-containing carbonized liquid is 0.8L / min, the volume fraction of carbon dioxide in the carbon dioxide-containing gas is 35%, and the ventilation flow rates of the three distributors are the same, all of which are 10.5L / min (under standard conditions, the empty tower gas flow rate is 0.36cm / s); the total production flow rate of the first product is 2.0L / min (the production flow rates of the three first discharge ports are the same). Part (flow rate of 1.2 L / min) of the liquid product (flow rate of 1.74 L / min) separated by filtration is circulated and added to the first feed port, mixed with fresh calcium-containing carbonized liquid and then introduced into a tower reaction device, and the solid product separated by filtration is dried to obtain a calcium carbonate product, the yield of the calcium carbonate product is 2.37 kg / h, the conversion rate of carbon dioxide in the preparation method is 78.2%, and the conversion rate of calcium is 91.2%. The obtained calcium carbonate product has a particle size of 4 μm, a whiteness of 98.1, and a purity of 98.2%.

[0055] Quicklime is used as a raw material to prepare a calcium hydroxide suspension as a calcium-containing carbonized liquid, wherein the content of calcium hydroxide is 100 g / L. The flow rate of the fresh calcium-containing carbonized liquid is 0.5 L / min, the volume fraction of carbon dioxide in the carbon dioxide-containing gas is 80%, the ventilation volume of the distributor in the second reaction unit is 9 L / min (under standard conditions, the empty tower gas flow rate is 0.30 cm / s), and the ventilation volume of the distributor in the two first reaction units is 12 L / min (under standard conditions, the empty tower gas flow rate is 0.33 cm / s); the total production flow rate of the first product is 1.5 L / min (the production flow rates of the three first discharge ports are the same). The liquid product (flow rate is 1.34L / min) separated by filtration is partially (flow rate is 1.0L / min) and circulated to the first feed port, mixed with fresh calcium-containing carbonized liquid and then passed into a tower reaction device, and the solid product separated by filtration is dried to obtain a calcium carbonate product, the yield of the calcium carbonate product is 5.1kg / h, the conversion rate of carbon dioxide in the preparation method is 76.1%, and the conversion rate of calcium hydroxide is 95.8%. The obtained calcium carbonate product is dried to constant weight at 105°C and analyzed by X-ray diffraction, which is a cava-type calcium carbonate with a particle size of 8μm, a whiteness of 97.5, a purity of 98.4%, and an average carbonization absorption rate of carbon dioxide of 95%.

[0056] The tower reaction device, calcium carbonate preparation system and method provided by the embodiment of the present invention, the tower reaction device is divided into a plurality of reaction units in the tower by a sieve plate, and a distributor is set in each reaction unit, so as to realize multi-point uniform gas distribution and multi-stage continuous carbonization, so that the gas containing carbon dioxide is uniformly distributed in the tower, and the absorption efficiency of carbon dioxide is effectively improved. The calcium carbonate preparation system adds an overflow tank in the tower reaction device, and adds a solid-liquid separation device outside, which can effectively control the residence time of the generated calcium carbonate in the tower, control the growth of calcium carbonate, and obtain fine calcium carbonate (particle size is micron-level), solve the problems of uneven calcium carbonate products prepared by traditional bubbling carbonization, and uncontrollable product particle size. Further, the preparation method of calcium carbonate provided by the present invention, which requires less equipment and has a simple process flow, not only makes the material more evenly distributed in the reaction device, improves the absorption efficiency of carbon dioxide, realizes effective control of the particle size of calcium carbonate products, but also increases the carbon dioxide content range of applicable gas, can process and utilize a variety of industrial waste gases, and the calcium carbonate product finally obtained also has high consistency and stability.

[0057] In the above description, the technical details such as the composition and processing methods of each component are not described in detail. However, those skilled in the art should understand that various technical means can be used to form cavities and grooves of desired shapes. In addition, although each embodiment is described above, it does not mean that the raw materials in each embodiment cannot be used in combination as needed.

[0058] The embodiments of the present invention are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A tower reaction device, comprising: A first reaction unit, wherein the first reaction unit comprises a first flow guide and a sieve plate, an overflow groove is formed between the first flow guide and a side wall of the first reaction unit, the sieve plate is located at the bottom of the first reaction unit, and the sieve plate has sieve holes; the opening rate of the sieve plate is 20% to 40%; the ratio of the diameter of the first flow guide to that of the first reaction unit is 0.7:1 to 0.85:1, and the ratio of the height of the first flow guide to that of the first reaction unit is 0.4:1 to 0.8:1; A second reaction unit, located below the first reaction unit and connected to the first reaction unit; Wherein, the first reaction unit and the second reaction unit are both provided with distributors to provide the first material to the tower reaction device, and the top of the tower reaction device is also provided with a first feed inlet and a gas outlet, the first feed inlet is used to provide the second material to the tower reaction device, the first material and the second material react in the tower reaction device, the first discharge port is provided at the side wall of the first reaction unit opposite to the overflow trough and at the bottom of the second reaction unit, the first reaction unit includes a plurality of first reaction units, the plurality of first reaction units are connected in sequence from top to bottom, and the bottommost first reaction unit is connected to the second reaction unit; the first flow guide and the distributor in the first reaction unit are both located above the sieve plate; the bottom of the first flow guide is connected to the side wall of the first reaction unit on its outer side. 2 . The tower reaction device according to claim 1 , wherein the first flow guide is cylindrical, the first flow guide is coaxial with the side wall of the first reaction unit, and the distributor is located inside the first flow guide.

3. According to the tower reaction device according to claim 1, the second reaction unit has a second flow guide member, the second flow guide member is cylindrical, the size of the second flow guide member corresponds to that of the first flow guide member, and the diameter of the second flow guide member at its bottom gradually decreases and corresponds to the first discharge port. 4 . The tower reaction device according to claim 1 , wherein a ratio of a height to a diameter of the first reaction unit is 1:1 to 4:

1.

5. The tower reaction device according to claim 1 further comprises a conduit, one end of which is connected to the first feed port, and the other end of which extends to the axis of the tower reaction device, so that the second material is input from the top axis of the tower reaction device.

6. A calcium carbonate preparation system, comprising: The tower reaction device according to any one of claims 1 to 5; The solid-liquid separation device comprises a second feed inlet, the first feed outlet of the tower reaction device is connected to the second feed inlet of the solid-liquid separation device, so as to provide part of the material in the tower reaction device to the solid-liquid separation device; Among them, the first feed inlet is used to provide calcium-containing carbonized liquid into the tower reaction device, the distributor is used to provide gas containing carbon dioxide into the tower reaction device, and the solid-liquid separation device is used to perform solid-liquid separation on the material provided by the first discharge port to obtain calcium carbonate solid.

7. The calcium carbonate preparation system according to claim 6, wherein the solid-liquid separation device comprises at least one of a sedimentation tank, a filter and a centrifuge.

8. According to the calcium carbonate preparation system of claim 6, the solid-liquid separation device is a sedimentation tank, and a second discharge port is provided at the bottom of the sedimentation tank to discharge the calcium carbonate precipitate; the upper side wall of the sedimentation tank is also provided with a third discharge port, and the third discharge port is connected to the first feed port of the tower reaction device to provide at least part of the liquid in the sedimentation tank together with the calcium-containing carbonized liquid to the tower reaction device.

9. The calcium carbonate preparation system according to claim 6, further comprising: A drying device is connected to the second discharge port of the solid-liquid separation device and is used to dry the calcium carbonate precipitate.

10. A method for preparing calcium carbonate, using the calcium carbonate preparation system according to claim 6, the method comprising: Passing the calcium-containing carbonized liquid into the tower reaction device; Passing a gas containing carbon dioxide into the tower reaction device; Passing the first product from the first discharge port into the solid-liquid separation device; The solid product obtained from the solid-liquid separation device is dried to obtain a calcium carbonate product.

11. The preparation method according to claim 10, further comprising: At least part of the liquid product obtained from the solid-liquid separation device is introduced into the tower reaction device together with the calcium-containing carbonized liquid.

12. The preparation method according to claim 10, wherein the calcium-containing carbonized liquid comprises at least one of a calcium hydroxide slurry and an ammonia solution of calcium chloride, and the mass fraction of calcium in the calcium-containing carbonized liquid is 6% to 18%.

13. The preparation method according to claim 10, wherein the gas containing carbon dioxide comprises at least one of waste gas from thermal power plants, coal chemical waste gas, and cement plant waste gas, and the mass fraction of carbon dioxide in the gas containing carbon dioxide is 5% to 90%.

14. preparation method according to claim 10, the flow velocity of the carbon dioxide gas provided by the distributor is 0.2~2cm / s, and the ratio of the molar flow rate of calcium in the calcium-containing carbonized liquid to the molar flow rate of carbon dioxide in the carbon dioxide gas is 1:1.1 to 1:1.

5.

15. The preparation method according to claim 11, wherein the volume flow ratio of the liquid product at least partially obtained from the solid-liquid separation device to the calcium-containing carbonized liquid is 2:1 to 5:1.

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