CO2 solidification system and method for gasification, black ash water softening, desiliconization and turbidity reduction

Abstract

The present invention provides a CO2 solidification system and method for softening, desiliconizing and de-turbidifying gasification black ash water. The system includes: a pH adjustment unit, a pipeline mixing unit, a first softening, desiliconizing and de-turbidifying unit, a second softening and desiliconizing unit, a water production unit and a sludge dewatering unit; the pH adjustment unit is provided with a first sludge discharge port, a pH regulator inlet, a first black ash water inlet and a first black ash water outlet. It can not only reduce the hardness of the gasification black ash water and remove silicon dioxide in the gasification black ash water, realizing synchronous softening, desiliconizing and de-turbidifying treatment of the gasification black ash water, solving the problems of easy scaling and blockage in the existing gasification black ash water treatment system, and making the reuse water system operate more efficiently, energy-saving, safe and stable, but also reasonably utilize the carbon dioxide tail gas, effectively reducing carbon dioxide gas emissions and realizing the solidification of carbon dioxide gas. Moreover, the system of the present application has a high degree of automation and can reduce manual operation.

Description

Technical Field

[0001] The present invention relates to the field of coal technology, and in particular to a CO2 solidification system and method for softening, removing silicon and reducing turbidity of gasified black ash water. Background Art

[0002] Coal is the energy with the strongest independent guarantee capability for my country's economic development and the ballast stone of my country's energy security. Among the proven fossil energy resource reserves in the country, coal accounts for more than 90%. This resource endowment characterized by "rich in coal" determines that my country's pattern of coal as the main energy source cannot be changed in the short term. In the process of economic development turning to the stage of high-quality development, efficient and clean use of coal is an inevitable requirement for the sustained and healthy development of energy supply.

[0003] At present, coal gasification is the main way to efficiently and cleanly utilize coal, and is a key common technology in the field of clean coal technology. However, the raw coal gas produced by the coal gasification process will produce a large amount of black water during the cooling and washing process. Multi-stage flash evaporation, sedimentation, and filtration process technologies are generally used for black water treatment. The silicon content of the treated black water (also known as gray water) is as high as (120-300) mg / L, and the hardness reaches (1200-2600) mg / L. Its main water quality characteristics are high hardness, suspended matter and silicon content. A part of it is returned to the system as circulating water for the gasification system, and part of the gray water needs to be discharged to the sewage treatment system. As a result, most of the recycled gray water causes serious blockage and scaling of pipeline equipment in the gasification water system, affecting the heat exchange efficiency of the gasification system, and the equipment is frequently shut down for abnormal inspection and maintenance. Some of the gray water sent to the water treatment unit will cause the accumulated inorganic ash content of the activated sludge in the biochemical system to be high and the organic content to be low, which directly affects the operation effect and treatment efficiency of the biochemical treatment section, and then causes the hardness and silicon content of the inlet water of the downstream deep treatment system to exceed the standard. Long-term operation will cause serious scaling of the downstream deep treatment system and supporting treatment facilities, causing serious blockage of the reverse osmosis membrane, resulting in the treatment capacity and recovery rate of the deep treatment stage failing to meet the design requirements, which seriously affects the recycling of coal gasification wastewater. In order to effectively reduce the operation and maintenance costs and fundamentally solve the scaling and fouling problems of the black gray water system and sewage treatment system, it is urgent to carry out efficient softening, desiliconization and turbidity reduction treatment of coal gasification black gray water. Summary of the invention

[0004] The main purpose of the present invention is to provide a CO2 solidification system and method for softening, removing silicon and reducing turbidity of gasified black ash water, so as to solve the problem of easy scaling and clogging of gasified ash water treatment systems in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a CO2 solidification system for gasifying black ash water, softening, removing silicon and reducing turbidity is provided, the system comprising: a pH adjusting unit, a pipeline mixing unit, a first softening, removing silicon and reducing turbidity unit, a second softening, removing silicon unit, a water production unit and a sludge dehydration unit; the pH adjusting unit is provided with a first mud discharge port, a pH adjusting agent inlet, a first black ash water inlet and a first black ash water outlet; the pipeline mixing unit is provided with a second black ash water inlet, a second black ash water outlet and a first desiliconizing agent inlet, and the second black ash water inlet is connected to the first black ash water outlet by a pipeline; the first softening, removing silicon and reducing turbidity unit comprises a first aeration unit, a first coagulation unit and a first sedimentation unit connected in sequence, the first aeration unit is provided with a third black ash water inlet connected to the second black ash water outlet by a pipeline, the top of the first aeration unit is provided with a second desiliconizing agent inlet and a first gas-water separation device, and the bottom of the first aeration unit is provided with a second mud discharge port and a first A carbon dioxide aeration unit, a third mud discharge port is provided at the bottom of the first coagulation unit, a first flocculant feeding port is provided at the top of the first coagulation unit, a first water outlet and a fourth mud discharge port are provided at the first sedimentation unit; the second softening and desiliconizing unit comprises a second aeration unit, a second coagulation unit and a second sedimentation unit which are connected in sequence, the second aeration unit is connected to the first water outlet, a second gas-water separation device is provided at the top of the second aeration unit, a fifth mud discharge port and a second carbon dioxide aeration unit are provided at the bottom of the second aeration unit, a sixth mud discharge port is provided at the bottom of the second coagulation unit, a second flocculant feeding port is provided at the top of the second coagulation unit, and a second water outlet and a seventh mud discharge port are provided at the second sedimentation unit; the water production unit is connected to the second water outlet; the sludge dehydration unit is connected to the first mud discharge port, the second mud discharge port, the third mud discharge port, the fourth mud discharge port, the fifth mud discharge port, the sixth mud discharge port and the seventh mud discharge port to dehydrate the sludge generated in the softening, desiliconizing and turbidity reduction system.

[0006] Furthermore, the first aeration unit also includes a second desiliconization agent feeding unit, a first carbon dioxide buffer device and a first discharge pipeline. The second desiliconization agent feeding unit is connected to the second desiliconization agent inlet, and the first carbon dioxide aeration unit is connected to the first carbon dioxide buffer device. Preferably, the first gas-water separation device is externally connected to the first discharge pipeline of the ozone treatment system; preferably, the second aeration unit also includes a second carbon dioxide buffer device and a second discharge pipeline, and the second carbon dioxide aeration unit is connected to the second carbon dioxide buffer device. Preferably, the second gas-water separation device is externally connected to the second discharge pipeline of the ozone treatment system; preferably, the first carbon dioxide buffer device and the second carbon dioxide buffer device are both electrically connected to the first control module.

[0007] Furthermore, the first carbon dioxide aeration unit and the second carbon dioxide aeration unit each independently include a plurality of aeration elements, which are arranged in a checkerboard pattern, with each aeration element being 0.5 to 1.5 meters apart from each other; preferably, the first carbon dioxide aeration unit is located 0 to 1.5 meters from the bottom of the first aeration unit 31 .

[0008] Furthermore, the first coagulation unit is provided with a fifth stirring device and a first pH measuring device, and the first pH measuring device is preferably connected to the control module; the first coagulation unit preferably also includes a first flocculant feeding device, the first flocculant feeding port is connected to the first flocculant feeding device, and the first flocculant feeding device is provided with a sixth stirring device; the second coagulation unit is preferably provided with an eighth stirring device and a second pH measuring device, and the second pH measuring device is preferably connected to the control module; the second coagulation unit also includes a second flocculant feeding device, and the second flocculant feeding port is connected to the second flocculant feeding device, and the second flocculant feeding device is provided with a ninth stirring device.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a CO2 solidification method for softening, removing silicon and reducing turbidity of gasified black ash water. The CO2 solidification method adopts the above-mentioned softening, removing silicon and reducing turbidity system. The softening, removing silicon and reducing turbidity method comprises: step S1, passing the gasified black ash water into a pH adjustment unit to adjust the pH of the gasified black ash water to obtain the gasified black ash water after pH adjustment; step S2, passing the gasified black ash water after pH adjustment into a pipeline mixing unit to remove silicon and obtain the gasified black ash water after siliconization; step S3, passing the gasified black ash water after siliconization into a first softening, removing silicon and reducing turbidity unit to perform preliminary siliconization and turbidity reduction to obtain the gasified black ash water after preliminary siliconization and turbidity reduction; step S4, passing the gasified black ash water after preliminary siliconization and turbidity reduction into a second softening, removing silicon and reducing turbidity unit to perform deep siliconization and turbidity reduction to obtain the gasified black ash water after siliconization and turbidity reduction.

[0010] Further, step S1 includes: passing the gasified black ash water into a pH adjustment unit, adding a pH adjuster from a pH adjuster feeding unit into the pH adjustment unit through a pH adjuster inlet to adjust the pH of the gasified black ash water, and obtaining gasified black ash water after pH adjustment; preferably, the pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide or lime; preferably, the residence time of the gasified black ash water in the pH adjustment unit 10 is 20 to 40 minutes; preferably, the pH of the gasified black ash water after pH adjustment is 11 to 12.

[0011] Furthermore, step S2 includes: passing the gasified black ash water after adjusting the pH into the pipeline mixing unit, adding the first desiliconizing agent from the first desiliconizing agent feeding unit through the first desiliconizing agent inlet into the pipeline mixing unit to remove silicon and obtain the gasified black ash water after desiliconization; the first desiliconizing agent is selected from one or more of magnesium oxide, magnesium sulfate, and magnesium chloride; preferably, the mass ratio of the first desiliconizing agent to the silica content in the gasified black ash water is 0.5 to 15:1.

[0012] Further, step S3 includes: step A, passing the desiliconized gasified black ash water into the first aeration unit, adding the second desiliconizing agent from the second desiliconizing agent feeding unit through the second desiliconizing agent feeding inlet to the first aeration unit to obtain desiliconized gasified black ash water; step B, passing the desiliconized gasified black ash water into the first coagulation unit, adding the flocculant from the first flocculant feeding device through the first flocculant feeding inlet to the first coagulation unit to obtain the gasified black ash water with preliminary turbidity reduction; step C, passing the gasified black ash water with preliminary turbidity reduction Pass the gasified black ash water with preliminary desiliconization and turbidity reduction into the first sedimentation unit to obtain gasified black ash water with preliminary desiliconization and turbidity reduction; step D, pass the gasified black ash water with preliminary desiliconization and turbidity reduction into the second aeration unit to obtain gasified black ash water with deep turbidity reduction; step E, pass the gasified black ash water with deep turbidity reduction into the second coagulation unit, add the flocculant from the second flocculant feeding device into the second coagulation unit through the flocculant feeding port to obtain gasified black ash water with deep turbidity reduction; step F, pass the gasified black ash water with deep turbidity reduction into the second sedimentation unit to obtain gasified black ash water with deep desiliconization and turbidity reduction.

[0013] Furthermore, in step B, the pH of the first coagulation unit is 9-10; preferably, in step E, the pH of the second coagulation unit is 7-8.

[0014] Furthermore, the second desiliconizing agent is selected from one or more of aluminum oxides, aluminates, and metal salts; preferably, the mass ratio of the second desiliconizing agent added to the silicon dioxide in the gasified black ash water after desiliconization is 0.2 to 10:1; preferably, the flocculant includes an inorganic polymer flocculant and / or polyacrylamide; preferably, the inorganic polymer flocculant is selected from one or more of polyaluminum chloride, polyferric chloride, and polyaluminum-ferric chloride; preferably, the amount of the inorganic polymer flocculant is 10 to 180 ppm; preferably, the amount of polyacrylamide is 1 to 10 ppm.

[0015] By applying the technical solution of the present invention, the system of the present application can not only reduce the hardness of coal gasification black ash water and remove silicon dioxide in coal gasification black ash water, but also realize the simultaneous softening, desiliconization and turbidity reduction treatment of coal gasification black ash water, solve the problem of easy scaling and clogging in the gasification black ash water treatment system in the prior art, and realize the operation of the recycled water system more efficiently, energy-saving, safe and stable. The present application can also reasonably utilize carbon dioxide tail gas, effectively reduce carbon dioxide gas emissions and realize the solidification of carbon dioxide gas. In addition, the system of the present application has a high degree of automation, which can reduce the number of personnel operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 A structural block diagram of a softening, desiliconizing and turbidity reducing system for gasifying black ash water according to an embodiment of the present invention is shown;

[0018] Figure 2 A schematic diagram of a softening, desiliconizing and turbidity reducing system for gasifying black ash water according to an embodiment of the present invention is shown.

[0019] The above drawings include the following reference numerals:

[0020] 10. pH adjustment unit; 20. Pipeline mixing unit; 30. First softening, desiliconization and turbidity reduction unit; 40. Second softening, desiliconization unit; 50. Water production unit; 60. Sludge dewatering unit;

[0021] 11. pH regulator dosing unit; 21. first desiliconizing agent dosing unit; 31. first aeration unit; 32. first coagulation unit; 33. first sedimentation unit; 41. second aeration unit; 42. second coagulation unit; 43. second sedimentation unit;

[0022] 111, the first stirring device; 211, the second stirring device; 311, the first gas-water separation device; 312, the second desiliconization agent feeding unit; 313, the first carbon dioxide buffer device; 314, the first discharge pipeline; 315, the third stirring device; 316, the fourth stirring device; 321, the fifth stirring device; 322, the first pH measuring device; 323, the first flocculant feeding device; 411, the second gas-water separation device; 412, the seventh stirring device; 413, the second carbon dioxide buffer device; 414, the second discharge pipeline; 421, the eighth stirring device; 422, the second pH measuring device; 423, the second flocculant feeding device. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] As analyzed in the background technology, at present, most of the recycled gray water causes serious blockage and scaling of pipeline equipment in the gasification water system, affecting the heat exchange efficiency of the gasification system, and the equipment is frequently shut down for abnormal inspection and maintenance. Some of the gray water sent to the water treatment unit will cause the accumulated inorganic ash content of the activated sludge in the biochemical system to be high and the organic content to be low, which directly affects the operation effect and treatment efficiency of the biochemical treatment section, and then causes the hardness and silicon content of the inlet water of the downstream deep treatment system to exceed the standard. Long-term operation will cause serious scaling of the downstream deep treatment system and supporting treatment facilities, causing serious blockage of the reverse osmosis membrane, resulting in the processing capacity and recovery rate of the deep treatment stage failing to meet the design requirements, which seriously affects the recycling of coal gasification wastewater. In order to solve the above problems, the present application provides a CO2 solidification system and method for softening, removing silicon and reducing turbidity of gasified black gray water.

[0025] In a typical embodiment of the present application, a CO2 solidification system for gasifying black ash water, softening, removing silicon and reducing turbidity is provided. Figure 1 and Figure 2As shown, the system includes: a pH adjusting unit 10, a pipeline mixing unit 20, a first softening and desiliconizing and turbidity reducing unit 30, a second softening and desiliconizing unit 40, a water producing unit 50, and a sludge dewatering unit 60; the pH adjusting unit 10 is provided with a first mud discharge port, a pH adjusting agent inlet, a first black ash water inlet and a first black ash water outlet; the pipeline mixing unit 20 is provided with a second black ash water inlet, a second black ash water outlet and a first desiliconizing agent inlet, and the second black ash water inlet is connected to the first black ash water outlet through a pipeline; the first softening and desiliconizing and turbidity reducing unit 30 includes a first aeration unit 31, a first coagulation unit 32, and a first sedimentation unit 33 connected in sequence, the first aeration unit 31 is provided with a third black ash water inlet connected to the second black ash water outlet through a pipeline, the top of the first aeration unit 31 is provided with a second desiliconizing agent inlet and a first gas-water separation device 311, the bottom of the first aeration unit 31 is provided with a second mud discharge port and a first carbon dioxide aeration unit, and the bottom of the first coagulation unit 32 is provided with There is a third mud outlet, a first flocculant feeding port is provided at the top of the first coagulation unit 32, and a first water outlet and a fourth mud outlet are provided at the first sedimentation unit 33; the second softening and silicon removal unit 40 includes a second aeration unit 41, a second coagulation unit 42, and a second sedimentation unit 43 connected in sequence, the second aeration unit 41 is connected to the first water outlet, a second gas-water separation device 411 is provided at the top of the second aeration unit 41, a fifth mud outlet and a second carbon dioxide aeration unit are provided at the bottom of the second aeration unit 41, a sixth mud outlet is provided at the bottom of the second coagulation unit 42, a second flocculant feeding port is provided at the top of the second coagulation unit 42, and a second water outlet and a seventh mud outlet are provided at the second sedimentation unit 43; the water production unit 50 is connected to the second water outlet; the sludge dehydration unit is connected to the first mud outlet, the second mud outlet, the third mud outlet, the fourth mud outlet, the fifth mud outlet, the sixth mud outlet, and the seventh mud outlet to dehydrate the sludge generated in the softening, silicon removal and turbidity reduction system.

[0026] The modern coal chemical industry has high-carbon properties. In order to replace petrochemicals in the production of chemical products, it is necessary to increase the "H / C hydrogen-carbon atomic ratio" in the synthesis gas produced by coal gasification through water-gas shift. A large amount of carbon dioxide will be produced in the processes of coal-to-methanol, olefins, ethylene glycol, natural gas and coal indirect liquefaction.

[0027] The system of the present application includes two groups of silicon removal and turbidity reduction units. The use of the first softening silicon removal and turbidity reduction unit 30 can reduce the silicon content to 30ppm, which can meet the process requirements. However, after the softening treatment of the first softening silicon removal and turbidity reduction unit 30, the hardness can only be reduced to about 500ppm. Therefore, the present application deeply softens the gasified black ash water by setting a second softening silicon removal unit 40 to further reduce the hardness to within 300ppm.

[0028] The system of the present application can not only reduce the hardness of coal gasification black ash water and remove silicon dioxide in coal gasification black ash water, realize the simultaneous softening, desiliconization and turbidity reduction treatment of coal gasification black ash water, solve the problem of easy scaling and clogging in the gasification black ash water treatment system in the prior art, and realize the operation of the recycled water system more efficient, energy-saving, safe and stable. The present application can also reasonably utilize carbon dioxide tail gas, effectively reduce carbon dioxide gas emissions and realize the solidification of carbon dioxide gas. In addition, the system of the present application has a high degree of automation, which can reduce the number of personnel operations.

[0029] The first aeration unit 31, the first coagulation unit 32, and the first sedimentation unit 33 can be integrated or separated, and the outlets of each unit are gradually reduced. The second aeration unit 41, the second coagulation unit 42, and the second sedimentation unit 43 are similar.

[0030] In order to make the raw materials mix evenly, in some embodiments, the pH adjusting unit 10 further includes a pH adjusting agent feeding unit 11, the pH adjusting agent inlet is connected to the pH adjusting agent feeding unit 11, and a first stirring device 111 is provided in the pH adjusting agent feeding unit 11, and the first stirring device 111 is preferably a stirrer. The pipeline mixing unit 20 further includes a first desiliconizing agent feeding unit 21, the first desiliconizing agent inlet is connected to the first desiliconizing agent feeding unit 21, and a second stirring device 211 is provided in the first desiliconizing agent feeding unit 21, and the second stirring device 211 is preferably a stirrer.

[0031] In some embodiments, the first aeration unit 31 also includes a second desiliconization agent feeding unit 312, a first carbon dioxide buffer device 313 and a first discharge pipeline 314. The second desiliconization agent feeding unit 312 is connected to the second desiliconization agent inlet, and the first carbon dioxide aeration unit is connected to the first carbon dioxide buffer device 313. Preferably, the first gas-water separation device 311 is externally connected to the first discharge pipeline 314 of the ozone treatment system; the second desiliconization agent feeding unit 312 is provided with a third stirring device 315, and preferably the third stirring device 315 is a stirrer. Preferably, the first aeration unit 31 also includes a fourth stirring device 316, and preferably the fourth stirring device is a stirrer.

[0032] Preferably, the second aeration unit 41 also includes a second carbon dioxide buffer device 413 and a second discharge pipeline 414, and the second carbon dioxide aeration unit is connected to the second carbon dioxide buffer device 413. Preferably, the second gas-water separation device 411 is externally connected to the second discharge pipeline 414 of the ozone treatment system; preferably, the second aeration unit also includes a seventh stirring device 412, and the seventh stirring device 412 is preferably a stirrer.

[0033] Preferably, the first carbon dioxide buffer device 313 and the second carbon dioxide buffer device 413 are both electrically connected to the control module. The module control unit can control the aeration amount of carbon dioxide.

[0034] In some embodiments, the first carbon dioxide aeration unit and the second carbon dioxide aeration unit each independently include a plurality of aeration elements, the aeration elements are arranged in a checkerboard pattern, and the distance between each aeration element is 0.5 to 1.5 meters; preferably, the first carbon dioxide aeration unit is located 0 to 1.5 meters from the bottom of the first aeration unit 31. The aeration unit can make CO2 fully contact with the gasified black ash water, increase the stirring rate, and fully solidify the carbon dioxide.

[0035] In some embodiments, a fifth stirring device 321 and a first pH measuring device 322 are provided inside the first coagulation unit 32, and the first pH measuring device 322 is preferably connected to the control module; preferably, the first coagulation unit 32 also includes a first flocculant feeding device 323, the first flocculant feeding port is connected to the first flocculant feeding device 323, and a sixth stirring device is provided inside the first flocculant feeding device 323; preferably, an eighth stirring device 421 and a second pH measuring device 422 are provided inside the second coagulation unit 42, and the second pH measuring device 422 is preferably connected to the control module; preferably, the second coagulation unit also includes a second flocculant feeding device 423, the second flocculant feeding port is connected to the second flocculant feeding device 423, and a ninth stirring device is provided inside the second flocculant feeding device 423.

[0036] In some embodiments, the first sedimentation unit 33 and the second sedimentation unit 43 further improve the solid-liquid separation effect by means of internal inclined tubes. The supernatant is qualified produced water and is stored in the water production unit 50, and the precipitate and the above-mentioned sludge are sent to the sludge dewatering unit 60.

[0037] In another typical embodiment of the present application, a CO2 solidification method for softening, removing silicon and reducing turbidity of gasified black ash water is provided. The softening, removing silicon and reducing turbidity method adopts the above-mentioned softening, removing silicon and reducing turbidity system, and the CO2 solidification method includes: step S1, passing the gasified black ash water into a pH adjustment unit 10 to adjust the pH of the gasified black ash water to obtain gasified black ash water with adjusted pH; step S2, passing the gasified black ash water with adjusted pH into a pipeline mixing unit 20 to remove silicon and obtain gasified black ash water with desiliconization; step S3, passing the gasified black ash water with desiliconization into a first softening, removing silicon and reducing turbidity unit 30 to perform preliminary removal of silicon and reducing turbidity to obtain gasified black ash water with preliminary removal of silicon and reducing turbidity; step S4, passing the gasified black ash water with preliminary removal of silicon and reducing turbidity into a second softening, removing silicon and reducing turbidity unit 40 to perform deep removal of silicon and reducing turbidity to obtain gasified black ash water with desiliconization and reducing turbidity.

[0038] The present application first adjusts the pH of the coal gasification black ash water to remove the temporary hardness of the gasification black ash water and provide a suitable acid-base environment for the subsequent silicon removal, carbon dioxide removal and hardness removal; then removes silicon through the pipeline mixing unit 20, and then deeply removes silicon and reduces the hardness of the gasification black ash water through two groups of silicon removal and turbidity reduction units. The softening, silicon removal and turbidity reduction method of the present application is simple, which can not only simultaneously remove silicon and turbidity from the coal gasification black ash water, but also reasonably utilize carbon dioxide, reduce carbon dioxide gas emissions and achieve the solidification of carbon dioxide gas. At the same time, the system using the present application can also save the amount of reagents used and reduce costs.

[0039] In some embodiments, step S1 includes: passing the gasified black ash water into the pH adjustment unit 10, adding the pH adjuster from the pH adjuster feeding unit 11 into the pH adjustment unit 10 through the pH adjuster inlet to adjust the pH of the gasified black ash water, and obtaining the gasified black ash water after pH adjustment. The main chemical reactions occurring in the pH adjustment unit 10 include:

[0040] HCO3 - +OH - +Ca 2+ →CaCO3↓+H2O

[0041] OH - +Mg 2+ →Mg(OH)2↓

[0042] OH - +Al 3+ +Al(OH)3↓↓↓

[0043] The present application has no particular limitation on the pH adjuster, as long as the pH of the coal gasification black ash water can be adjusted to alkaline. Preferably, the pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide or lime.

[0044] The preferred residence time of the gasified black ash water in the pH adjustment unit 10 is 20 to 40 minutes; the residence time of the gasified black ash water in the pH adjustment unit 10 should not be too long, otherwise it will cause mud and scale to clog related equipment. If the residence time is too short, the pH will not meet the requirements, which will reduce the softening and silicon removal efficiency.

[0045] In order to save costs and improve the efficiency of hardness removal and silica removal, it is preferred to adjust the pH to 11 to 12. When the pH is lower than 11, the hardness and silica removal rates will decrease, and when the pH is higher than 12, the cost of the reagent will increase significantly.

[0046] In some embodiments, step S2 includes: passing the pH-adjusted gasified black ash water into the pipeline mixing unit 20, and adding the first desiliconizing agent from the first desiliconizing agent feeding unit 21 through the first desiliconizing agent inlet into the pipeline mixing unit 20 to remove silicon and obtain gasified black ash water after desiliconization. The present application performs desiliconization in the pipeline mixing unit 20 to preliminarily reduce the silica content in the gasified black ash water.

[0047] The present application has no particular limitation on the first desiliconizing agent, and any commonly used desiliconizing agent in the art can be applied to the present application. Preferably, the first desiliconizing agent is selected from one or more of magnesium oxide, magnesium sulfate, and magnesium chloride.

[0048] The flow rate of the first desiliconizing agent is related to the agent concentration and the silica content in the black ash water. In industry, it is only necessary to limit the agent-silicon ratio. The preferred mass ratio of the first desiliconizing agent to the silica content in the gasified black ash water is 0.5-15:1; if the content of the first desiliconizing agent is too high, it will cause agent residues and increase the subsequent treatment cost; if the content of the first desiliconizing agent is too low, the silica removal effect will be reduced.

[0049] In some embodiments, step S3 includes: step A, passing the desiliconized gasified black ash water into the first aeration unit 31, adding the second desiliconizing agent from the second desiliconizing agent feeding unit 312 to the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the desiliconized gasified black ash water; step B, passing the desiliconized gasified black ash water into the first coagulation unit 32, adding the flocculant from the first flocculant feeding device 323 to the first coagulation unit 32 through the first flocculant feeding inlet to obtain the gasified black ash water with preliminary turbidity reduction; step C, adding the gasified black ash water with preliminary turbidity reduction to the first coagulation unit 323; step S4, passing the desiliconized gasified black ash water into the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the gasified black ash water with preliminary turbidity reduction; step S5, passing the desiliconized gasified black ash water into the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the gasified black ash water with preliminary turbidity reduction; step S6, passing the desiliconized gasified black ash water into the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the gasified black ash water with preliminary turbidity reduction; step S7, passing the desiliconized gasified black ash water into the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the gasified black ash water with preliminary turbidity reduction; step S8, passing the desiliconized gasified black ash water into the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the gasified black ash water with preliminary turbidity reduction; step S9, passing the desiliconized gasified black ash water into the first aeration unit 31 through the second desiliconizing agent feeding inlet to obtain the gasified black ash The grey water is passed into the first sedimentation unit 33 to obtain gasified black grey water with preliminary desiliconization and turbidity reduction; in step D, the gasified black grey water with preliminary desiliconization and turbidity reduction is passed into the second aeration unit 41 to obtain gasified black grey water with deep turbidity reduction; in step E, the gasified black grey water with deep turbidity reduction is passed into the second coagulation unit 42, and the flocculant is added from the second flocculant feeding device 423 to the second coagulation unit 42 through the flocculant feeding port to obtain gasified black grey water with deep turbidity reduction; in step F, the gasified black grey water with deep turbidity reduction is passed into the second sedimentation unit 43 to obtain gasified black grey water with deep desiliconization and turbidity reduction.

[0050] The desiliconizing agent reacts with silicon and hardness (calcium) in the gasified black ash water in the first aeration unit 31 to generate solid matter, which can better achieve solid-liquid separation and be sent to the first coagulation unit 32. After the gasified black ash water acts with the flocculant in the first coagulation unit 32 and the second coagulation unit 42, it is sent to the first sedimentation unit 33 and the second sedimentation unit 43 to achieve solid-liquid separation, thereby achieving the purpose of softening and desiliconization.

[0051] The main chemical reactions occurring in step A and step D of this application are:

[0052] CO2+OH - +Ca 2+ →CaCO3↓+H2O

[0053] In step B and step E of the present application, the calcium carbonate generated by the aeration reaction in step A and step D forms large-grained "alum flowers" under the action of the flocculant, and then overflows to the sedimentation area to accelerate sedimentation and separation.

[0054] In some embodiments, in step B, the pH of the first coagulation unit 32 is 9 to 10; preferably in step E, the pH of the second coagulation unit 42 is 7 to 8. The amount of carbon dioxide aeration is related to the amount of water treated and the purity of carbon dioxide gas. This application only needs to determine the pH of the effluent after aeration. This application controls the pH by adjusting the amount of carbon dioxide aeration, which can improve the silicon removal efficiency of the silicon removal agent, and can also improve the rate and efficiency of solidifying carbon dioxide and the rate and efficiency of softening. If pH control is not performed, the pH value of the raw water (untreated coal gasification black ash water) is 7 to 8, the silicon removal rate of the silicon removal agent is only about 10%, and the rate and efficiency of carbon fixation and softening are also greatly reduced, both of which are only 20% to 30% of the pH control condition.

[0055] In some embodiments, the second desiliconizing agent is selected from one or more of aluminum oxides, aluminates, and metal salts; preferably, the mass ratio of the amount of the second desiliconizing agent added to the silicon dioxide in the gasified black ash water after silicon removal is 0.2 to 10:1; the above silicon dioxide refers to the silicon dioxide in the gasified black ash water after silicon removal. The first desiliconizing agent and the second desiliconizing agent are in a coupled relationship. Due to the different forms of silicon in the water, the first agent and the second agent have a synergistic effect, and the effects of silicon removal, carbon dioxide removal, and hardness removal are all improved.

[0056] In order to fully settle the calcium carbonate generated by the aeration reaction, preferably, the flocculant includes an inorganic polymer flocculant and / or polyacrylamide;

[0057] Preferably, the inorganic polymer flocculant is selected from one or more of polyaluminium chloride, polyferric chloride and polyaluminium ferric chloride; preferably, the dosage of the inorganic polymer flocculant is 10-180ppm; preferably, the dosage of polyacrylamide is 1-10ppm. The inorganic polymer flocculant has high density, low flocculation efficiency and high dosage, while polyacrylamide has light weight, high flocculation efficiency and low dosage, and the coupling flocculation clarification effect of the two is the best.

[0058] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0059] Embodiment 1:

[0060] The ash water discharged from the pulverized coal pressurized entrained flow gasification device has a water temperature of 35°C, a total hardness of 2160 mg / L, and a total silicon content of 276 mg / L.

[0061] (1) The above-mentioned ash water is passed to a pH adjustment unit, and a sodium hydroxide solution with a concentration of 20 wt% is added to the ash water. The pH of the ash water is controlled to be 12 by controlling the amount of the solution added, thereby obtaining gasified black ash water after pH adjustment;

[0062] (2) After the pH of the gasified black ash water is adjusted, it stays in the pH adjustment unit for 30 minutes, and then is pressure-sent to the first softening, desiliconization and turbidity reduction unit through the pipeline mixing unit. 800 mg / L of magnesium sulfate with a concentration of 20wt% is added in the pipeline mixing unit, and 130 mg / L of sodium aluminate with a concentration of 45wt% is added in the first softening, desiliconization and turbidity reduction unit. The pH of the first coagulation solution is controlled to be 10 by controlling the carbon dioxide aeration amount, and 5 mg / L of cationic polyacrylamide with a concentration of 1wt‰ is added in the first coagulation unit. In the first softening, desiliconization and turbidity reduction unit, the residence time in the first aeration unit, the first coagulation unit, and the first precipitation unit are 60 minutes, 20 minutes, and 120 minutes, respectively. After staying in the first softening, desiliconization and turbidity reduction unit for a total of 200 minutes, the gasified black ash water with preliminary desiliconization and turbidity reduction is obtained;

[0063] (3) The above-mentioned gasified black ash water with preliminary desiliconization and turbidity reduction is passed into the second deep softening and desiliconization unit. The pH value of the second coagulation solution is controlled to 7.5 by controlling the carbon dioxide aeration rate. 800 mg / L of 17 wt% polyaluminum ferric sulfate and 2 mg / L of 1 wt‰ cationic polyacrylamide are added to the second coagulation unit. In the second deep softening and desiliconization unit, the residence time in the second aeration unit, the second coagulation unit, and the second precipitation unit are 60 min, 20 min, and 120 min, respectively, to obtain gasified black ash water with desiliconization and turbidity reduction.

[0064] (4) After the above-mentioned gasified black ash water with silicon removal and turbidity reduction is separated by mud and water in the second sedimentation unit, the upper clear liquid is discharged from the system and the sludge is discharged to the sludge treatment system. Analysis shows that the total hardness of the upper clear liquid is reduced to 206 mg / L and the total silicon content is reduced to 19 mg / L. The total hardness removal rate is calculated to reach 90.5% and the total silicon removal rate is 93.1%, as shown in Table 1.

[0065] Example 2

[0066] The black water from the pulverized coal pressurized entrained flow gasification device has a water temperature of 70°C, a total hardness of 2346 mg / L, a total silicon content of 307 mg / L, and a suspended matter content of 10 wt%.

[0067] (1) The above-mentioned ash water is passed to a pH adjustment unit, and a sodium hydroxide solution with a concentration of 20 wt% is added to the ash water. The pH of the ash water is controlled to be 12 by controlling the amount of the solution added, thereby obtaining gasified black ash water after pH adjustment;

[0068] (2) After the pH-adjusted gasified black ash water is allowed to stay in the pH adjustment unit for 20 minutes, it is then pressure-transferred to the first softening, desiliconization and turbidity reduction unit through the pipeline mixing unit, 800 mg / L of 20wt% magnesium sulfate is added to the pipeline mixing unit, 130 mg / L of 45wt% sodium aluminate is added to the first softening, desiliconization and turbidity reduction unit, the pH of the coagulation solution is controlled to be 10 by controlling the carbon dioxide aeration volume, and 2 mg / L of 1wt‰ cationic polyacrylamide is added to the first coagulation unit. In the first softening, desiliconization and turbidity reduction unit, the residence time in the first aeration unit, the first coagulation unit, and the first precipitation unit are 60 minutes, 20 minutes, and 120 minutes, respectively. After staying in the first softening, desiliconization and turbidity reduction unit for a total of 200 minutes, the gasified black ash water with preliminary desiliconization and turbidity reduction is obtained;

[0069] (3) The above-mentioned gasified black ash water with preliminary desiliconization and turbidity reduction is passed into the second deep softening and desiliconization unit. The pH value of the coagulation solution is controlled to 8 by controlling the carbon dioxide aeration rate. 1000 mg / L of 17 wt% polyaluminum ferric sulfate and 2 mg / L of 1 wt‰ cationic polyacrylamide are added to the second coagulation unit. In the second deep softening and desiliconization unit, the residence time in the second aeration unit, the second coagulation unit, and the second precipitation unit are 60 min, 20 min, and 120 min, respectively, to obtain gasified black ash water with desiliconization and turbidity reduction.

[0070] (4) After the second sedimentation unit separates mud and water, the supernatant is discharged from the system and the sludge is discharged to the sludge treatment system. Analysis of the supernatant showed that the total hardness dropped to 227 mg / L, the total silicon content dropped to 24 mg / L, and the turbidity dropped to 3 NTU. The total hardness removal rate was calculated to be 90.3% and the total silicon removal rate was 92.2%.

[0071] Example 3

[0072] Different from Example 1,

[0073] (1) The above-mentioned ash water is passed to a pH adjustment unit, and a sodium hydroxide solution with a concentration of 20 wt% is added to the ash water. The pH of the ash water is controlled to be 12 by controlling the amount of the solution added, thereby obtaining gasified black ash water after pH adjustment;

[0074] (2) After the pH of the gasified black ash water is adjusted, it stays in the pH adjustment unit for 30 minutes, and then is pressure-sent to the first softening, desiliconization and turbidity reduction unit through the pipeline mixing unit. 2760 mg / L of magnesium sulfate with a concentration of 20 wt% is added in the pipeline mixing unit, and 3067 mg / L of sodium aluminate with a concentration of 45 wt% is added in the first softening, desiliconization and turbidity reduction unit. The pH of the coagulation solution is adjusted to 10 by controlling the amount of carbon dioxide aeration, and 10 mg / L of cationic polyacrylamide with a concentration of 1 wt‰ is added to the first coagulation unit. In the first softening, desiliconization and turbidity reduction unit, the residence time in the first aeration unit, the first coagulation unit, and the first precipitation unit are 60 minutes, 20 minutes, and 120 minutes, respectively. After staying in the first softening, desiliconization and turbidity reduction unit for a total of 200 minutes, the gasified black ash water with preliminary desiliconization and turbidity reduction is obtained;

[0075] (3) The above-mentioned gasified black ash water with preliminary silicon removal and turbidity reduction is passed into the second deep softening and silicon removal unit. The pH value of the coagulation solution is controlled to 7.5 by controlling the carbon dioxide aeration rate. 100 mg / L of 17 wt% polyaluminum ferric sulfate and 1 mg / L of 1 wt‰ cationic polyacrylamide are added to the second coagulation unit. In the second deep softening and silicon removal unit, the residence time in the second aeration unit, the second coagulation unit, and the second precipitation unit are 60 min, 20 min, and 120 min, respectively, to obtain gasified black ash water with silicon removal and turbidity reduction.

[0076] (4) After the above-mentioned gasified black ash water with silicon removal and turbidity reduction passes through the second sedimentation unit for mud and water separation, the upper clear liquid is discharged from the system and the sludge is discharged to the sludge treatment system.

[0077] Example 4

[0078] Different from Example 1,

[0079] (1) The above-mentioned ash water is passed to a pH adjustment unit, and a sodium hydroxide solution with a concentration of 20 wt% is added to the ash water. The pH of the ash water is controlled to be 12 by controlling the amount of the solution added, thereby obtaining gasified black ash water after pH adjustment;

[0080] (2) After the pH of the gasified black ash water is adjusted, it stays in the pH adjustment unit for 30 minutes, and then is pressure-sent to the first softening, desiliconization and turbidity reduction unit through the pipeline mixing unit. 1380 mg of 20 wt% magnesium sulfate is added to the pipeline mixing unit, and 613 mg / L of 45 wt% sodium aluminate is added to the first softening, desiliconization and turbidity reduction unit. The pH of the coagulation solution is adjusted to 10 by controlling the carbon dioxide aeration amount, and 5 mg / L of cationic polyacrylamide with a concentration of 1 wt‰ is added to the first coagulation unit. In the first softening, desiliconization and turbidity reduction unit, the residence time in the first aeration unit, the first coagulation unit, and the first precipitation unit are 60 minutes, 20 minutes, and 120 minutes, respectively. After staying in the first softening, desiliconization and turbidity reduction unit for a total of 200 minutes, the gasified black ash water with preliminary desiliconization and turbidity reduction is obtained;

[0081] (3) The above-mentioned gasified black ash water with preliminary desiliconization and turbidity reduction is passed into the second deep softening and desiliconization unit. The pH value of the coagulation solution is controlled to 7.5 by controlling the carbon dioxide aeration rate. The second coagulation unit is added with 59 mg / L of 17 wt% polyaluminum ferric sulfate and 7 mg / L of 1 wt‰ cationic polyacrylamide. In the second deep softening and desiliconization unit, the residence time in the second aeration unit, the second coagulation unit, and the second sedimentation unit are 60 min, 20 min, and 120 min, respectively, to obtain gasified black ash water with desiliconization and turbidity reduction.

[0082] (4) After the above-mentioned gasified black ash water with silicon removal and turbidity reduction passes through the second sedimentation unit for mud and water separation, the upper clear liquid is discharged from the system and the sludge is discharged to the sludge treatment system.

[0083] Example 5

[0084] The difference from Example 1 is that in step (2), 21.4 g / L of 20 wt% magnesium sulfate is added to the pipeline mixing unit.

[0085] Example 6

[0086] The difference from Example 1 is that in step (2), the pipeline mixing unit adds 138 mg / L of 20 wt% magnesium sulfate.

[0087] Example 7

[0088] The difference from Example 1 is that in step (2), 6136 mg / L of sodium aluminate with a concentration of 45 wt% is added to the pipeline mixing unit.

[0089] Example 8

[0090] The difference from Example 1 is that in step (2), 57.6 mg / L of sodium aluminate with a concentration of 45 wt% is added to the pipeline mixing unit.

[0091] Example 9

[0092] The difference from Example 1 is that in step (1), the amount of pH regulator added is controlled so that the pH of the discharged ash water is 10.

[0093] Example 10

[0094] The difference from Example 1 is that in step (2), the CO2 aeration rate is controlled so that the pH of the first coagulation solution is 8.

[0095] Embodiment 11

[0096] The difference from Example 1 is that in step (3), the CO2 aeration rate is controlled so that the pH of the second coagulation solution is 9.

[0097] Comparative Example 1

[0098] pH adjustment unit not included.

[0099] Comparative Example 2

[0100] The difference from Example 1 is that the second desiliconizing agent feeding unit is not included.

[0101] Table 1

[0102] Total hardness / mg / L Total silicon content / mg / L Total hardness removal rate / % Total silicon removal rate / % Black and gray water 2160 276 / / Example 1 206 19 90.5 93.1 Example 2 227 24 90.3 92.2 Example 3 273 2 87.4 99.3 Example 4 197 28 90.9 89.8 Example 5 335 26 84.5 90.6 Example 6 181 35 91.6 87.3 Example 7 238 13 89.0 95.3 Example 8 213 29 90.1 89.5 Example 9 410 21 81.0 92.4 Example 10 479 87 77.8 68.5 Embodiment 11 258 26 88.1 90.6 Comparative Example 1 1087 157 49.7 43.1 Comparative Example 2 896 121 58.5 56.2

[0103] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0104] The system of the present application can not only reduce the hardness of coal gasification black ash water and remove silicon dioxide in coal gasification black ash water, but also realize the simultaneous softening, desiliconization and turbidity reduction treatment of coal gasification black ash water, solve the problem of easy scaling and clogging in the gasification black ash water treatment system in the prior art, and realize the operation of the recycled water system more efficiently, energy-saving, safe and stable. The present application can also reasonably utilize carbon dioxide tail gas, effectively reduce carbon dioxide gas emissions and realize the solidification of carbon dioxide gas. In addition, the system of the present application has a high degree of automation, which can reduce the number of personnel operations.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A CO2 solidification system for gasifying black ash water, softening, removing silicon and reducing turbidity, characterized in that: The system comprises: A pH regulating unit (10), wherein the pH regulating unit (10) is provided with a first mud discharge port, a pH regulating agent inlet, a first black ash water inlet and a first black ash water outlet, so as to adjust the pH of the gasified black ash water to 11-12, thereby obtaining the gasified black ash water after the pH is adjusted; A pipeline mixing unit (20), wherein the pipeline mixing unit (20) is provided with a second black ash water inlet, a second black ash water outlet and a first desiliconizing agent inlet, wherein the second black ash water inlet is connected to the first black ash water outlet via a pipeline; A first softening, desiliconizing and turbidity reducing unit (30), the first softening, desiliconizing and turbidity reducing unit (30) comprising a first aeration unit (31), a first coagulation unit (32) and a first sedimentation unit (33) connected in sequence, the first aeration unit (31) being provided with a third black ash water inlet connected to the second black ash water outlet via a pipeline, the top of the first aeration unit (31) being provided with a second desiliconizing agent inlet and a first gas-water separation device (311), the bottom of the first aeration unit (31) being provided with a second mud discharge port and a first carbon dioxide aeration unit, the bottom of the first coagulation unit (32) being provided with a third mud discharge port, the top of the first coagulation unit (32) being provided with a first flocculant feeding port, and the first sedimentation unit (33) being provided with a first water outlet and a fourth mud discharge port; A second softening and desiliconizing unit (40), wherein the second softening and desiliconizing unit (40) comprises a second aeration unit (41), a second coagulation unit (42), and a second sedimentation unit (43) which are connected in sequence, wherein the second aeration unit (41) is connected to the first water outlet, a second air-water separation device (411) is provided at the top of the second aeration unit (41), a fifth mud discharge port and a second carbon dioxide aeration unit are provided at the bottom of the second aeration unit (41), a sixth mud discharge port is provided at the bottom of the second coagulation unit (42), a second flocculant feeding port is provided at the top of the second coagulation unit (42), and the second sedimentation unit (43) is provided with a second water outlet and a seventh mud discharge port; a water production unit (50), the water production unit (50) being connected to the second water outlet; A sludge dewatering unit (60) is connected to the first sludge discharge port, the second sludge discharge port, the third sludge discharge port, the fourth sludge discharge port, the fifth sludge discharge port, the sixth sludge discharge port, and the seventh sludge discharge port to dewater the sludge generated in the softening, desiliconization, and turbidity reduction system.

2. The CO2 curing system according to claim 1, characterized in that: The first aeration unit (31) further comprises a second desiliconizing agent feeding unit (312), a first carbon dioxide buffer device (313) and a first discharge pipeline (314); the second desiliconizing agent feeding unit (312) is connected to the second desiliconizing agent inlet; the first carbon dioxide aeration unit is connected to the first carbon dioxide buffer device (313); and the first gas-water separation device (311) is externally connected to the first discharge pipeline (314) of the ozone treatment system.

3. The CO2 curing system according to claim 2, characterized in that: The second aeration unit (41) further comprises a second carbon dioxide buffer device (413) and a second discharge pipeline (414), and the second carbon dioxide aeration unit is connected to the second carbon dioxide buffer device (413).

4. The CO2 curing system according to claim 3, characterized in that: The second gas-water separation device (411) is externally connected to a second discharge pipeline (414) of the ozone treatment system.

5. The CO2 curing system according to claim 2, characterized in that: The first carbon dioxide buffer device (313) and the second carbon dioxide buffer device (413) are both electrically connected to the first control module.

6. The CO2 curing system according to claim 1, characterized in that: The first carbon dioxide aeration unit and the second carbon dioxide aeration unit each independently include a plurality of aeration elements, the aeration elements are arranged in a checkerboard pattern, and the aeration elements are spaced 0.5 to 1.5 meters apart from each other.

7. The CO2 curing system according to claim 6, characterized in that: The first carbon dioxide aeration unit is located 0 to 1.5 meters from the bottom of the first aeration unit (31).

8. The CO2 curing system according to claim 1, characterized in that: A fifth stirring device (321) and a first pH measuring device (322) are provided inside the first coagulation unit (32).

9. The CO2 curing system according to claim 8, characterized in that: The first pH measuring device (322) is connected to the control module.

10. The CO2 curing system according to claim 8, characterized in that: The first coagulation unit (32) further comprises a first flocculant feeding device (323), the first flocculant feeding port is connected to the first flocculant feeding device (323), and a sixth stirring device is arranged in the first flocculant feeding device (323).

11. The CO2 curing system according to claim 8, characterized in that: The second coagulation unit (42) is provided with an eighth stirring device (421) and a second pH measuring device (422) inside; the second coagulation unit (42) also includes a second flocculant feeding device (423).

12. The CO2 curing system according to claim 11, characterized in that: The second pH measuring device (422) is connected to the control module.

13. The CO2 curing system according to claim 11, characterized in that: The second flocculant feeding port is connected to the second flocculant feeding device (423), and a ninth stirring device is provided in the second flocculant feeding device (423).

14. A CO2 solidification method for gasifying black ash water to soften, remove silicon and reduce turbidity, characterized in that: The CO2 solidification method adopts the softening, desiliconization and turbidity reduction system according to any one of claims 1 to 13, and the softening, desiliconization and turbidity reduction method comprises: Step S1, passing the gasified black ash water into the pH adjustment unit (10) to adjust the pH of the gasified black ash water to 11-12, thereby obtaining the gasified black ash water after pH adjustment; Step S2, passing the pH-adjusted gasified black ash water into the pipeline mixing unit (20) to remove silicon, thereby obtaining the desiliconized gasified black ash water; Step S3, passing the desiliconized gasified black ash water into the first softening desiliconization and turbidity reduction unit (30) to perform preliminary desiliconization and turbidity reduction, thereby obtaining gasified black ash water with preliminary desiliconization and turbidity reduction; Step S4, passing the gasified black ash water with preliminary desiliconization and turbidity reduction into the second softening and desiliconization unit (40) to perform deep desiliconization and turbidity reduction to obtain gasified black ash water with desiliconization and turbidity reduction.

15. The CO2 solidification method according to claim 14, characterized in that: The step S1 comprises: The gasified black ash water is passed into the pH adjustment unit (10), and the pH adjustment agent is added into the pH adjustment unit (10) from the pH adjustment agent feeding unit (11) through the pH adjustment agent inlet to adjust the pH of the gasified black ash water, thereby obtaining the gasified black ash water after the pH is adjusted.

16. The CO2 solidification method according to claim 15, characterized in that: The pH regulator is selected from one or more of sodium hydroxide, potassium hydroxide or lime.

17. The CO2 solidification method according to claim 15, characterized in that: The residence time of the gasified black ash water in the pH adjustment unit (10) is 20 to 40 minutes.

18. The CO2 solidification method according to claim 14, characterized in that: The step S2 comprises: The pH-adjusted gasified black ash water is introduced into the pipeline mixing unit (20), and the first desiliconizing agent is added from the first desiliconizing agent feeding unit (21) into the pipeline mixing unit (20) through the first desiliconizing agent inlet to remove silicon and obtain the gasified black ash water after desiliconization.

19. The CO2 solidification method according to claim 18, characterized in that: The first silicon removal agent is selected from one or more of magnesium oxide, magnesium sulfate and magnesium chloride.

20. The CO2 solidification method according to claim 18, characterized in that: The mass ratio of the first desiliconizing agent to the silicon dioxide content in the gasified black ash water is 0.5 to 15:

1.

21. The CO2 solidification method according to claim 14, characterized in that: The step S3 comprises: Step A, passing the desiliconized gasified black ash water into the first aeration unit (31), adding the second desiliconizing agent from the second desiliconizing agent feeding unit (312) through the second desiliconizing agent feeding inlet into the first aeration unit (31), to obtain the desiliconized gasified black ash water; Step B, passing the desiliconized gasified black ash water into the first coagulation unit (32), adding the flocculant from the first flocculant feeding device (323) through the first flocculant feeding port into the first coagulation unit (32), to obtain the gasified black ash water with preliminary turbidity reduction; Step C, passing the preliminarily turbidity-reduced gasified black ash water into the first sedimentation unit (33) to obtain preliminarily desiliconized and turbidity-reduced gasified black ash water; Step D, passing the gasified black ash water with preliminary silicon removal and turbidity reduction into the second aeration unit (41) to obtain gasified black ash water with deep turbidity reduction; Step E, passing the deeply turbidity-reduced gasified black ash water into the second coagulation unit (42), adding flocculant from the second flocculant feeding device (423) through the flocculant feeding port into the second coagulation unit (42), to obtain deeply turbidity-reduced gasified black ash water; Step F, passing the deeply de-turbidified gasified black ash water into the second sedimentation unit (43) to obtain deeply desiliconized and de-turbidified gasified black ash water.

22. The CO2 solidification method according to claim 21, characterized in that: In the step B, the pH of the first coagulation unit (32) is 9-10.

23. The CO2 solidification method according to claim 22, characterized in that: In the step E, the pH of the second coagulation unit (42) is 7-8.

24. The CO2 solidification method according to claim 14, characterized in that: The second silicon removal agent is selected from one or more of aluminum oxides, aluminates, and metal salts.

25. The CO2 solidification method according to claim 24, characterized in that: The mass ratio of the added amount of the second desiliconizing agent to the silicon dioxide in the gasified black ash water after desiliconization is 0.2 to 10:

1.

26. The CO2 solidification method according to claim 24, characterized in that: The flocculant includes an inorganic polymeric flocculant and / or polyacrylamide.

27. The CO2 solidification method according to claim 26, characterized in that: The inorganic polymer flocculant is selected from one or more of polyaluminium chloride, polyferric chloride and polyaluminium-ferric chloride.

28. The CO2 solidification method according to claim 26, characterized in that: The dosage of the inorganic polymer flocculant is 10 to 180 ppm; the dosage of the polyacrylamide is 1 to 10 ppm.

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