CN216440316U - Double-tower type dry and semi-dry desulfurized fly ash aeration oxidation device - Google Patents
Double-tower type dry and semi-dry desulfurized fly ash aeration oxidation device Download PDFInfo
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- CN216440316U CN216440316U CN202122875369.5U CN202122875369U CN216440316U CN 216440316 U CN216440316 U CN 216440316U CN 202122875369 U CN202122875369 U CN 202122875369U CN 216440316 U CN216440316 U CN 216440316U
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- 238000005273 aeration Methods 0.000 title claims abstract description 84
- 239000010881 fly ash Substances 0.000 title claims abstract description 65
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 55
- 230000003647 oxidation Effects 0.000 title claims abstract description 52
- 239000002002 slurry Substances 0.000 claims abstract description 88
- 239000007788 liquid Substances 0.000 claims abstract description 32
- 230000009102 absorption Effects 0.000 claims abstract description 27
- 238000010521 absorption reaction Methods 0.000 claims abstract description 27
- 239000002253 acid Substances 0.000 claims abstract description 26
- 230000009103 reabsorption Effects 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 32
- 230000018044 dehydration Effects 0.000 claims description 9
- 238000006297 dehydration reaction Methods 0.000 claims description 9
- 229910052602 gypsum Inorganic materials 0.000 claims description 9
- 239000000523 sample Substances 0.000 claims description 9
- 239000010440 gypsum Substances 0.000 claims description 8
- 238000012806 monitoring device Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 53
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- 230000008569 process Effects 0.000 abstract description 20
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- 238000000354 decomposition reaction Methods 0.000 abstract 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 26
- 239000002699 waste material Substances 0.000 description 16
- 230000009471 action Effects 0.000 description 12
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 8
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- 239000000126 substance Substances 0.000 description 7
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- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
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- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229920000881 Modified starch Polymers 0.000 description 1
- 239000004368 Modified starch Substances 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
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- 239000003153 chemical reaction reagent Substances 0.000 description 1
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Abstract
The utility model relates to a double towerFormula dry process, semi-dry process desulfurization ash aeration oxidation unit, the main points are: the whole device consists of an aeration tower and SO2The device comprises an absorption tower, a first aeration head, a second aeration head, a first slurry pump, a second slurry pump, a first air blower, a second air blower, an acid liquid pump, a first stirrer, a second stirrer and the like; the conventional one-step oxidation process is decomposed into multiple steps, the pH of the slurry in each step is accurately controlled, and SO is combined2The reabsorption measures not only avoid CaSO3A large amount of decomposition and SO2Secondary pollution and ensures sufficient CaSO3In a liquid phase reaction system, the problem of slow oxidation rate caused by high alkalinity of the dry and semi-dry desulfurized fly ash is finally solved, and clean and efficient modification of the desulfurized fly ash is creatively realized.
Description
Technical Field
The utility model belongs to the technical field of resources and environment, relates to stabilization modification and resource utilization of dry-process and semi-dry-process desulfurized fly ash, and particularly relates to a double-tower type dry-process and semi-dry-process desulfurized fly ash aeration oxidation device and an operation method of the device.
Background
In recent years, due to the high importance of our country on the ecological environment protection, and the high importance of our country on SO2The emission requirements are becoming more and more strict, and the flue gas desulfurization process is widely popularized and applied in the industries of coal-fired power plants, steel sintering, industrial boilers, petrochemical industry and the like, wherein the dry and semi-dry desulfurization processes represented by CFB, LIFAC, NID, SDA and CDSI have the advantages of small occupied area, low investment, low operating cost, low energy consumption, no sewage and waste acid emission and the like, and become the trend of the future development of the flue gas desulfurization technology.
The dry and semi-dry desulfurizing process features that powdered or granular calcium-base absorbent is used to eliminate SO from fume2The desulfurization product is dry powder and mainly comprises CaSO3·1/2H2O、CaCO3、CaSO4·2H2O and a small amount of unreacted Ca (OH)2And the like. Compared with wet desulphurization process, the desulphurization ash produced by dry and semi-dry desulphurization process has much more complex components, and has the characteristics of high sulfur, high calcium and high alkalinity, especially CaSO3The proportion of the component (A) is high, and the component with poor chemical stability enables the dry-method and semi-dry-method desulfurized ash to show unusual physicochemical properties. Because the research on the properties, the reaction characteristics and the action mechanism of the solid wastes is not systematic and deep, people have more attentions on the comprehensive utilization of the solid wastes at present, an effective utilization way is not formed, so that the dry-process and semi-dry-process desulfurized ash is accumulated in a large quantity or is simply buried, a large amount of valuable land resources are occupied, the enterprise burden is increased, and the further popularization and application of the dry-process and semi-dry-process desulfurized process are restricted. Furthermore, since CaSO3Is unstable and is easy to cause SO after long-term stacking2Release of (a) and pose a potential threat to the environment; meanwhile, the dry-process and semi-dry-process desulfurization ash has small particle size and light weight, and can generate dust pollution once blown by wind.
For the comprehensive utilization of the dry-process and semi-dry-process desulfurized fly ash, the related work at home and abroad does not form a complete system at present, the obtained achievements belong to the research nature, any technology for large-scale industrial application is not formed, and the following four aspects are mainly considered:
(1) the chemical composition of the desulphurisation ash is quite complex. The phase compositions of the general dry and semi-dry desulfurized fly ash comprise CaSO4、CaSO3、CaCO3、Ca(OH)2、CaO、MgCO3And the components are complex and diversified in chemical property, so that the comprehensive utilization is more limited and more difficult.
(2) The fluctuation of the content of each component of the desulfurized fly ash is large. Due to the differences of the operation, operation and management levels of different enterprises, the differences of different raw material types and proportioning schemes, the differences of desulfurization efficiencies of different desulfurization processes and the differences of components of different batches of coal, the content of each component of desulfurization ash generated by different desulfurization equipment and different periods of time of the same equipment can fluctuate greatly. Such fluctuations bring about frequent changes in the overall chemistry, which makes its comprehensive utilization difficult.
(3) The chemical nature of the various components in the desulfurized fly ash is unstable. CaSO in desulfurized fly ash3、Ca(OH)2And CaO is chemically unstable and changes with environmental and time changes. CaSO3Easily decomposed in acid environment or under high temperature condition of neutral or reducing atmosphere to make SO2Is released again to cause secondary pollution of the environment, and simultaneously CaSO3Will be oxidized into CaSO in the air4Resulting in instability of the properties of the desulfurized fly ash material over long periods of use. CaO readily absorbs water to form Ca (OH)2Causing a volume-inhomogeneous expansion, Ca (OH)2Reabsorbing CO from air2To produce CaCO3. These instabilities pose a major obstacle to the comprehensive utilization of the desulfurized fly ash.
(4) CaSO in desulfurized fly ash3Has a high content of and CaSO3The action effect and mechanism of the drug are not clear. CaSO in dry and semi-dry desulfurized fly ash3The content of (A) can be up to more than 50%, and CaSO3The influence on the overall mechanical properties and stability of the material is yet to be further researched and confirmed. For example, when desulfurized fly ash is used as a cement retarder, CaSO3The retarding effect and the influence on the mechanical property of the cement are still greatly controversial.
In conclusion, under the new background that China vigorously advances the aim of 'non-waste cities' and 'double-carbon' construction, dry-process and semi-dry-process desulfurized ash is scientifically treated and utilized on a large scale to realize harmlessness and deep recycling, so that the method not only is a technical problem to be solved urgently in the industries such as coal-fired power plants, steel sintering, industrial boilers, petrifaction and the like in China, but also is necessary for advancing ecological civilization construction in China, promoting high-quality development and realizing comprehensive conservation and recycling of resources.
Based on the basic chemical principle of acid-base neutralization and oxidation-reduction, the desulfurization ash of the dry method and the semi-dry method is subjected to forced oxidation modification in the sulfuric acid environment, so that the limitation can be solvedThe problems of the four aspects of large-scale comprehensive utilization of the solid wastes are as follows: CaCO in desulfurized ash under the action of acid-base neutralization reaction3、Ca(OH)2And the basic components such as CaO and the like are all rapidly converted into CaSO4(ii) a And CaSO with poor stability under the action of oxidation reaction3Will also be converted into CaSO4. Thus, the original dry and semi-dry desulfurized fly ash with complex and various components and unstable content and chemical properties of various components is converted into stable CaSO4Is a solid waste with chemical properties similar to those of wet-process desulfurization gypsum as a main component. Because the technical problems of each link in the comprehensive utilization of the wet desulphurization gypsum are basically solved, the modified dry and semi-dry desulphurization ash can be comprehensively utilized on a large scale according to various technical routes of the wet desulphurization gypsum, thereby thoroughly solving the increasingly urgent treatment problem of the large solid wastes. Meanwhile, the resource utilization of the waste sulfuric acid is realized.
However, due to SO3 2-Will react with excessive H+Combine to form pollutant SO2Therefore, the pH of the reaction solution cannot be too low; meanwhile, the pH value of the solution is rapidly increased in the dissolving process due to strong alkalinity of the desulfurized fly ash, and CaSO3The solubility of (a) is very low and further decreases with the increase of the pH value, so that the oxidation rate is greatly reduced, and therefore, the solid-to-liquid ratio in the dissolving process, namely the pH value of the solution, cannot be too high. In conclusion, the high-efficiency oxidation of the dry and semi-dry desulfurized fly ash is realized in a one-step method and a conventional slurry manner, and the SO-free desulfurization is realized2The release is very difficult and innovative oxidative modification devices and methods adapted to the characteristics of the desulfurized fly ash need to be developed.
Disclosure of Invention
In order to solve the technical problems in the background art, the utility model provides a double-tower type dry-method and semi-dry-method desulfurized fly ash aeration oxidation device and an operation method thereof, wherein the double-tower type dry-method and semi-dry-method desulfurized fly ash aeration oxidation device has the advantages of low cost, stable operation, convenient construction and flexible operation.
In order to achieve the aim, the utility model provides a double-tower type dry and semi-dry desulfurized fly ash aeration oxidation device, which is characterized in that: it comprisesTwo reaction towers, i.e. aeration tower and SO2An absorption tower;
the SO2The absorption tower is a tower with a main body in a vertical cylindrical shape and a height-diameter ratio of 2-10, 2-4 aeration heads are arranged at a lower position in the tower in a parallel connection mode and are arranged at equal intervals along the circumference of the cross section of the tower; the number of the stirrers is 2-4, the stirrers correspond to the aeration heads one by one and are arranged on the same horizontal plane of the aeration heads; the desulfurized fly ash feeding pipe, the flexible joint, the exhaust pipe, the liquid level meter flange and the pressure meter flange are arranged at the top of the tower; the pH probe flanges are arranged on the side wall of the tower at equal intervals from top to bottom; the thermometer flange is arranged on the side wall of the middle part of the tower; the densimeter flange is arranged on the side wall of the middle lower part of the tower; the manhole is arranged on the lower side wall of the tower; the slurry discharge pipe and the clear water feed pipe are arranged at the bottom of the tower; the inlet of the slurry pump is connected with the slurry discharge pipe and the clear water pipe through a three-way pipeline; the number of the oxidation air pipes is 2-4, the oxidation air pipes correspond to the aeration heads one by one, and outlets of the air blowers are connected with the aeration heads through the oxidation air pipes; the flexible joint is connected with a desulfurized fly ash feeding pipe;
the aeration tower comprises SO2The absorption tower also comprises a reabsorption slurry merging pipe arranged on the side wall of the middle lower part of the aeration tower; the acid liquor feeding pipe is arranged at the bottom of the aeration tower; the outlet of the slurry pump is connected with the clear water feeding pipe and the gypsum dehydration unit through a three-way pipeline; the outlet of the acid liquor pump is connected with an acid liquor feeding pipe;
aeration tower and SO2The absorption towers are connected in the following way: SO (SO)2The outlet of the absorption tower slurry pump is communicated with SO through a three-way pipeline2The absorption tower clear water feeding pipe and the reabsorption slurry merging pipe are connected; SO (SO)2The inlet of the air blower of the absorption tower is connected with the exhaust pipe of the aeration tower.
The operation treatment method of the double-tower dry and semi-dry desulfurized fly ash aeration oxidation device comprises the following steps:
the method comprises the following steps: and (4) analyzing and testing raw materials. Analyzing and testing the components of the dry-method and semi-dry-method desulfurized fly ash to determine CaSO in the desulfurized fly ash3And the contents of various strongly basic compounds.
Step two: and (5) preparing alkali liquor. Only the inlet of the second slurry pump is opened,An outlet clean water pipeline for supplying the SO with a second slurry pump2Clean water is injected into the absorption tower, and when the liquid level is higher than 2/3-3/4 of the total liquid level, the clean water feeding is stopped; conveying the desulfurized ash into SO through the second flexible joint and the second desulfurized ash feeding pipe by using a pipe chain or a screw conveyer2An absorption tower; continuously operating the second stirrer to quickly and fully mix and dissolve the desulfurized fly ash and the clear water to finally form a pH value>10, after which the desulfurized fly ash feed is stopped.
Step three: and (4) preparing acid liquor. Gradually injecting waste sulfuric acid with low heavy metal and organic pollutant contents and mass fraction of 1-95% into the aeration tower by using the acid liquid pump; only opening a water inlet pipeline and a water outlet pipeline of the first slurry pump, and injecting clean water into the aeration tower by using the first slurry pump; continuously operating the first stirrer to quickly and fully mix and dissolve the waste sulfuric acid and the clear water; and when the pH value of the solution in the tower is stabilized between 2.2 and 4.2 and the liquid level is higher than 2/3 to 3/4 of the total liquid level, stopping feeding the waste sulfuric acid and the clean water.
Step four: and (4) acidifying the desulfurized fly ash. Conveying the desulfurized fly ash into an aeration tower through the first flexible joint and the first desulfurized fly ash feeding pipe by using a pipe chain or a screw conveyor; under the action of the first stirrer, the desulfurized fly ash entering the tower is quickly and fully mixed with acid liquor, dissolved and reacted; and stopping feeding the desulfurized fly ash when the pH value of the solution rises to 3.1-6.2 and is kept stable.
Step five: and (4) forced oxidation. Continuously operating said first blower, said first blower supplying air through a first oxidative air line to said first aeration head which injects air in the form of a plurality of fine bubbles into said solution of step four; under the action of the first stirrer, the bubbles are further broken and spirally ascend, so that the contact area and time of the bubbles and the solution are increased, and the full mass transfer process is completed; HSO in solution at this time3 -To be protected by O2Oxidation to SO4 2-To release H+Thereby lowering the pH of the solution.
Step six: and (5) carrying out secondary acidification. When the pH value of the solution in the fifth step tends to be stable, starting the acid liquid pump, and gradually adding the waste sulfuric acid in the third step into the aeration tower; under the action of the first stirrer, the waste sulfuric acid entering the tower is quickly and fully mixed with the solution and reacts, the pH value of the solution is reduced to 2.2-4.2 again, and then the acid liquid pump is closed.
Step seven: and (4) carrying out multi-step circulation. Continuously repeating the fourth step to the sixth step to ensure that solid CaSO gradually exists in the solution in the sixth step4And separating out, and finally forming slurry with the solid content of 6-30%.
Step eight: and (4) partially discharging the slurry. When the liquid level or the density of the slurry in the step seven reaches a certain value, only opening an inlet slurry pipeline and an outlet dehydration unit pipeline of the first slurry pump, discharging a part of the slurry by using the first slurry pump, and feeding the slurry into a dehydration unit to produce a gypsum product; keeping the liquid level in the aeration tower higher than 2/3-3/4 of the total liquid level in the slurry discharging process; and after the slurry discharge is finished, closing the first slurry pump and the inlet slurry pipeline and the outlet dehydration unit pipeline thereof.
Step nine: SO (SO)2And (4) absorbing again. During multi-stage cyclic oxidation, especially secondary acidification, there may be local too low pH of the slurry resulting in incompletely oxidized SO3 2-With excess H+Combine to release SO2In the case of (3), this fraction of SO2Will be discharged through said first exhaust pipe; continuously operating the second blower, and leading the part of SO to pass through the second oxidation air pipe by the second blower2Is fed to said second aeration head, which feeds SO2Injecting the alkaline slurry of the second step in the form of a large number of fine bubbles; under the action of the second stirrer, the bubbles are further broken and spirally raised, SO that the contact area and the contact time of the bubbles and the slurry are increased, and the SO is finished2And (4) a resorption process.
Step ten: the reabsorbed slurry is merged. Continuously absorbing SO with the alkaline slurry of the second step2The pH value thereof gradually decreases; when the temperature is reduced to below 8.5 and the secondary acidification of the step six is finished, only the inlet slurry pipeline and the outlet reabsorption slurry merging pipeline of the second slurry pump are opened, and a second slurry pump is utilizedAnd the slurry pump feeds the alkaline slurry into an aeration tower for merging and oxidation treatment.
Step eleven: and finishing the modification. And continuously repeating the second step, the fourth step and the tenth step to finally finish the oxidation modification of the desulfurization ash by the dry method and the semi-dry method.
Compared with the prior art, the utility model has the following beneficial effects:
(1) the pH value of the acidified slurry in the whole oxidation process is controlled to be 2.2-6.2 all the time based on the optimal solid-liquid ratio, so that CaSO in the desulfurized ash can be avoided to the maximum extent3Decompose to release SO2And can ensure enough CaSO3In a liquid phase reaction system, thereby remarkably improving the reaction rate of the whole oxidation process.
(2) The conventional one-step oxidation process is decomposed into multiple steps, and the problem of slow oxidation rate caused by high alkalinity of the dry-method and semi-dry-method desulfurized ash is solved by accurately controlling the solid-to-liquid ratio and the pH value of slurry in each step of oxidation process, so that the high-efficiency oxidation of the high alkalinity desulfurized ash is creatively realized.
(3) The method can simultaneously realize the resource utilization of the dry-process and semi-dry-process desulfurized fly ash and the waste sulfuric acid, thereby achieving the purposes of treating waste by waste and realizing synergistic circulation and obtaining better economic and environmental benefits.
(4) Using a double column reactor type, with a second column for SO2And the secondary pollution risk is further reduced by carrying out reabsorption.
(5) The flexible joint can effectively relieve the harmful vibration transmitted between the desulfurization ash conveying equipment and the reaction tower while ensuring the system tightness, and improves the safety and stability of the system operation.
Drawings
FIG. 1 is a schematic diagram of the apparatus of the present invention;
FIG. 2 shows the desulfurized ash and 80% concentrated H from a semi-dry process in a steel plant2SO4The reagent is used as raw material, pH regulation acidification and forced oxidation laboratory tests are carried out according to the step method of the utility model, and finally when the solid content of the slurry reaches 10 percent, the slurry comes from CaSO3Schematic diagram of S-balance.
The reference numbers in fig. 1 are as follows: 1-aeration tower, 2-SO2An absorption tower, 3-a first aeration head, 4-a second aeration head, 5-a first slurry pump, 6-a second slurry pump, 7-a first blower, 8-a second blower, 9-an acid liquor pump, 10-a first stirrer, 11-a second stirrer, 12-a first desulfurized fly ash feeding pipe, 13-a second desulfurized fly ash feeding pipe, 14-a first flexible joint, 15-a second flexible joint, 16-a first oxidized air pipe, 17-a second oxidized air pipe, 18-a first exhaust pipe, 19-a second exhaust pipe, 20-a first level gauge flange, 21-a second level gauge flange, 22-a first density gauge flange, 23-a second pressure gauge flange, 24-a first pH gauge flange, 25-a second pH gauge flange, 26-a first temperature gauge flange, 27-a second temperature gauge flange, 28-a first density gauge flange, 29-a second density gauge flange, 30-a reabsorption slurry merging pipe, 31-a first slurry discharge pipe, 32-a second slurry discharge pipe, 33-an acid liquid feed pipe, 34-a first clear water feed pipe, 35-a second clear water feed pipe, 36-a first manhole, and 37-a second manhole.
Detailed Description
The utility model is further described with reference to the following figures and specific examples.
As shown in figures 1-2, the utility model relates to a double-tower type dry and semi-dry desulfurized fly ash aeration oxidation device, which comprises an aeration tower 1 and SO2And an absorption tower 2.
The aeration tower 1 is characterized in that the number of the first aeration heads 3 is 2-4, the first aeration heads are arranged at the lower position in the aeration tower 1 in a parallel mode and are arranged at equal intervals along the circumference of the cross section of the aeration tower 1; the number of the first stirrers 10 is 2-4, the first stirrers correspond to the first aeration heads 3 one by one, and the first stirrers are arranged on the same horizontal plane of the first aeration heads 3; the first desulfurized fly ash feeding pipe 12, the first flexible joint 14, the first exhaust pipe 18, the first liquid level meter flange 20 and the first pressure meter flange 22 are arranged at the top of the aeration tower 1; the first pH probe flanges 24 are arranged on the side wall of the aeration tower 1 at equal intervals from top to bottom; the first thermometer flange 26 is arranged on the middle side wall of the aeration tower 1; the first densimeter flange 28 is arranged on the side wall of the middle lower part of the aeration tower 1; the first manhole 36 is arranged on the lower side wall of the aeration tower 1; the first slurry discharge pipe 31 and the first clear water feed pipe 34 are arranged at the bottom of the aeration tower 1; the inlet of the first slurry pump 5 is connected with the first slurry discharge pipe 31 and the clean water pipe through a three-way pipeline; the number of the first air oxidation pipes 16 is 2-4, the first air oxidation pipes correspond to the first aeration heads 3 one by one, and the outlets of the first air blowers 7 are connected with the first aeration heads 3 through the first air oxidation pipes 16; the first flexible joint 14 is connected to the first desulphurisation ash feed pipe 12.
SO2The absorption column 2 is identical to the aeration column described above, i.e. the components and equipment of the aeration column 1, in SO2The same position of the absorption tower 2 is also provided with the same number, structure, function and connection of corresponding parts and devices, respectively distinguished by the "second" in the names of the parts.
As a unique component, equipment and connection mode of the aeration tower 1, the device also comprises a reabsorption slurry merging pipe 30 arranged on the side wall of the middle lower part of the aeration tower 1; the acid liquor feeding pipe 33 is arranged at the bottom of the aeration tower 1; the outlet of the first slurry pump 5 is connected with the first clear water feed pipe 34 and the gypsum dehydration unit through a three-way pipeline; the outlet of the acid liquid pump 9 is connected with the acid liquid feeding pipe 33.
Aeration column 1 and SO2The absorption towers 2 are connected in the following way: the outlet of the second slurry pump 6 is connected with a second clear water feeding pipe 35 and a reabsorption slurry merging pipe 30 through a three-way pipeline; the inlet of the second blower 8 is connected to a first exhaust pipe 18.
The aeration tower 1 and SO2The absorption tower 2 is in a vertical cylindrical shape, and the height-diameter ratio is 2-10.
The first stirrer 10 and the second stirrer 11 are of a side-in type.
The first blower 7 and the second blower 8 both adopt roots blowers or centrifugal blowers.
The acid liquid pump 9 adopts a metering pump.
The first flexible joint 14 and the second flexible joint 15 both use a rubber corrugated pipe as a main body.
The number of the first pH probe flange 24 and the second pH probe flange 25 is 3-10, and the first pH probe flange and the second pH probe flange are respectively arranged along the aeration tower 1 and the SO2The absorption towers 2 are arranged at equal intervals from top to bottom in the height direction.
The second exhaust pipe 19 is provided with SO2Provided is an online monitoring device.
The operation treatment method of the double-tower dry and semi-dry desulfurized fly ash aeration oxidation device is characterized by comprising the following steps of: the method comprises the following eleven steps:
the method comprises the following steps: and (4) analyzing and testing raw materials. Analyzing and testing the components of the dry-method and semi-dry-method desulfurized fly ash to determine CaSO in the desulfurized fly ash3And the contents of various strongly basic compounds.
Step two: and (5) preparing alkali liquor. Only opening the inlet and outlet clean water pipelines of the second slurry pump 6, and utilizing the second slurry pump 6 to supply the SO2Clean water is injected into the absorption tower 2, and when the liquid level is higher than 2/3-3/4 of the total liquid level, the clean water feeding is stopped; the desulfurized fly ash is sent to SO through the second flexible joint 15 and the second desulfurized fly ash feeding pipe 13 by using a pipe chain or a screw conveyer2An absorption tower 2; continuously operating the second stirrer 11 to rapidly and fully mix and dissolve the desulfurized fly ash and the clear water to finally form a pH value>10, after which the desulfurized fly ash feed is stopped.
Step three: and (4) preparing acid liquor. Gradually injecting waste sulfuric acid with low heavy metal and organic pollutant contents and mass fraction of 1-95% into the aeration tower 1 by using the acid liquid pump 9; only opening the inlet and outlet clean water pipelines of the first slurry pump 5, and injecting clean water into the aeration tower 1 by using the first slurry pump 5; continuously operating the first stirrer 10 to rapidly and fully mix and dissolve the waste sulfuric acid and the clear water; and when the pH value of the solution in the tower is stabilized between 2.2 and 4.2 and the liquid level is higher than 2/3 to 3/4 of the total liquid level, stopping feeding the waste sulfuric acid and the clean water.
Step four: and (4) acidifying the desulfurized fly ash. Feeding the desulfurized fly ash into the aeration tower 1 through the first flexible joint 14 and the first desulfurized fly ash feeding pipe 12 by using a pipe chain or a screw conveyor; under the action of the first stirrer 10, the desulfurized fly ash entering the tower is quickly and fully mixed with the acid liquor, dissolved and reacted; and stopping feeding the desulfurized fly ash when the pH value of the solution rises to 3.1-6.2 and is kept stable.
Step five: and (4) forced oxidation. Continuously operating said first blower 7, said first blower 7 sending air through a first oxidative air pipe 16 to said first aeration head 3, which injects air in the form of a plurality of fine bubbles into the solution of said step four; under the action of the first stirrer 10, the bubbles are further broken and spirally rise, so that the contact area and time of the bubbles and the solution are increased, and the full mass transfer process is completed; HSO in solution at this time3 -To be protected by O2Oxidation to SO4 2-To release H+Thereby lowering the pH of the solution.
Step six: and (5) carrying out secondary acidification. When the pH value of the solution in the fifth step tends to be stable, starting the acid liquid pump 9, and gradually adding the waste sulfuric acid in the third step into the aeration tower 1; under the action of the first stirrer 10, the waste sulfuric acid entering the tower is quickly and fully mixed with the solution, the reaction process is completed, the pH value of the solution is reduced to 2.2-4.2 again, and then the acid liquid pump 9 is closed.
Step seven: and (4) carrying out multi-step circulation. Continuously repeating the fourth step to the sixth step to ensure that solid CaSO gradually exists in the solution in the sixth step4And separating out, and finally forming slurry with the solid content of 6-30%.
Step eight: and (5) partially discharging the slurry. When the liquid level or the density of the slurry in the step seven reaches a certain numerical value, only opening an inlet slurry pipeline and an outlet dehydration unit pipeline of the first slurry pump 5, discharging a part of the slurry by using the first slurry pump 5, and sending the slurry into a dehydration unit to produce a gypsum product; in the slurry discharging process, the liquid level in the aeration tower 1 is kept higher than 2/3-3/4 of the total liquid level; and after the slurry discharge is finished, closing the first slurry pump 5 and the inlet slurry pipeline and the outlet dehydration unit pipeline thereof.
Step nine: SO (SO)2And (4) absorbing again. During multi-stage cyclic oxidation, especially secondary acidification, there may be local too low pH of the slurry resulting in incompletely oxidized SO3 2-With excess H+Combine to release SO2In the case of (3), this fraction of SO2Will exit through the first exhaust pipe 18; the second blower 8 is continuously operated, and the second blower 8 is communicatedThe second oxidation air pipe 17 discharges the part of SO2Is fed to said second aeration head 4, which feeds SO2Injecting the alkaline slurry of the second step in the form of a large number of fine bubbles; under the action of the second stirrer 11, these bubbles are further broken and rise spirally, increasing the contact area and time with the solution, thereby completing SO2And (4) a resorption process.
Step ten: the reabsorbed slurry is merged. Continuously absorbing SO with the alkaline slurry of the second step2The pH value thereof gradually decreases; when the temperature is reduced to below 8.5 and the secondary acidification of the step six is completed, only the inlet slurry pipeline and the outlet reabsorption slurry merging pipeline of the second slurry pump 6 are opened, and the second slurry pump 6 is utilized to send the alkaline slurry into the aeration tower 1 for merging and oxidation treatment.
Step eleven: and finishing the modification. And continuously repeating the second step, the fourth step and the tenth step to finally finish the oxidation modification of the desulfurization ash by the dry method and the semi-dry method.
The original components of the semidry desulfurized fly ash of a certain steel plant are shown in Table 1. pH regulation acidification and forced oxidation tests are carried out according to the step method of the utility model, and when the solid content of the final slurry reaches 10%, the final slurry comes from CaSO3S-balance of (a) is shown in fig. 2. Table 2 shows the composition of the resulting oxidation product. As can be seen, CaSO is the most main component in the original semi-dry desulfurized fly ash3And CaCO339.65% and 32.77%, respectively, and a certain amount of MgCO3And Ca (OH)2Equal high alkalinity component, CaSO4The content of (A) is very low. Almost all CaSO in the original semi-dry desulfurized fly ash is obtained by the step method of the utility model3，CaCO3And Ca (OH)2Are all converted into dihydrate CaSO4At the same time SO2Has little escape, and the dihydrate CaSO in the oxidation product4The content of the modified starch reaches 93.97 percent, and a good modification effect is obtained.
TABLE 1 original composition of semidry desulfurized fly ash (dry basis)
TABLE 2 composition of the oxidation products (dry basis)
The embodiments described above are intended to enable those skilled in the art to fully understand and effectively use the utility model. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-mentioned embodiments, and modifications made by those skilled in the art according to the teachings of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.
Claims (7)
1. The double-tower dry and semi-dry desulfurized fly ash aeration oxidation device is characterized in that: it comprises two reaction towers, namely an aeration tower and SO2An absorption tower;
the SO2The absorption tower is a tower with a main body in a vertical cylindrical shape and a height-diameter ratio of 2-10, 2-4 aeration heads are arranged at a lower position in the tower in a parallel connection mode and are arranged at equal intervals along the circumference of the cross section of the tower; the number of the stirrers is 2-4, the stirrers correspond to the aeration heads one by one and are arranged on the same horizontal plane of the aeration heads; the desulfurized fly ash feeding pipe, the flexible joint, the exhaust pipe, the liquid level meter flange and the pressure meter flange are arranged at the top of the tower; the pH probe flanges are arranged on the side wall of the tower at equal intervals from top to bottom; the thermometer flange is arranged on the side wall of the middle part of the tower; the densimeter flange is arranged on the side wall of the middle lower part of the tower; the manhole is arranged on the lower side wall of the tower; the slurry discharge pipe and the clear water feed pipe are arranged at the bottom of the tower; the inlet of the slurry pump is connected with the slurry discharge pipe and the clear water pipe through a three-way pipeline; the number of the oxidation air pipes is 2-4, the oxidation air pipes correspond to the aeration heads one by one, and outlets of the air blowers are connected with the aeration heads through the oxidation air pipes; the flexible joint is connected with a desulfurized fly ash feeding pipe;
said exposure to lightThe gas tower comprises SO2The absorption tower also comprises a reabsorption slurry merging pipe arranged on the side wall of the middle lower part of the aeration tower; the acid liquor feeding pipe is arranged at the bottom of the aeration tower; the outlet of the slurry pump is connected with the clear water feeding pipe and the gypsum dehydration unit through a three-way pipeline; the outlet of the acid liquor pump is connected with an acid liquor feeding pipe;
aeration tower and SO2The absorption towers are connected in the following way: SO (SO)2The outlet of the absorption tower slurry pump is communicated with SO through a three-way pipeline2The absorption tower clear water feeding pipe and the reabsorption slurry merging pipe are connected; SO (SO)2The inlet of the air blower of the absorption tower is connected with the exhaust pipe of the aeration tower.
2. The twin tower dry and semi-dry desulfurized fly ash aeration oxidation unit according to claim 1, wherein: the stirrer is of a side-in type.
3. The twin tower dry and semi-dry desulfurized fly ash aeration oxidation unit according to claim 1, wherein: the blower is a Roots blower or a centrifugal blower.
4. The twin tower dry and semi-dry desulfurized fly ash aeration oxidation unit according to claim 1, wherein: the number of the pH probe flanges is 3-10, and the pH probe flanges are arranged at equal intervals from top to bottom along the height direction of the tower respectively.
5. The twin tower dry and semi-dry desulfurized fly ash aeration oxidation unit according to claim 1, wherein: the flexible joints all use rubber corrugated pipes as main bodies.
6. The twin tower type dry and semi-dry desulfurized fly ash aeration oxidation unit according to claim 1, wherein: SO (SO)2The exhaust pipe of the absorption tower is provided with SO2Provided is an online monitoring device.
7. The twin tower dry and semi-dry desulfurized fly ash aeration oxidation unit according to claim 1, wherein: the acid liquid pump adopts a metering pump.
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