A system and process for producing calcium carbonate from desulfurized gypsum in an ammonia environment in multiple stages in series

Abstract

This invention discloses a multi-stage series-connected system and process for producing calcium carbonate from gypsum using ammonia-environmental desulfurization, comprising a gypsum reaction tower, a tail gas purification tower, a tail gas deep purification tower, a gypsum slurry preparation system, and a flue gas source. The gypsum slurry preparation system, the tail gas deep purification tower, the tail gas purification tower, and the gypsum reaction tower are connected in series along the flow direction of the gypsum slurry. An ammonia source is connected to the gypsum reaction tower to supply ammonia water. The gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower are connected in series along the flow direction of the tail gas. The flue gas source is connected to the slurry pools of the gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower, respectively, to introduce flue gas into them. A slurry spray layer is provided at the upper end of each of the gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower. The slurry spray layer is connected to the slurry pool through a circulation pipe and is located above the tail gas inlet.

Description

Technical Field

[0001] This invention belongs to the field of solid waste utilization technology of desulfurized gypsum, specifically relating to a system and process for producing calcium carbonate from ammonia-environment desulfurized gypsum in a multi-stage series connection. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Currently, desulfurized gypsum is mainly used in the production of gypsum powder, gypsum products, and cement retarder in the construction industry. Under the conditions of ammonia water (ammonia gas) and CO2, as shown in the following chemical complex reaction equation, desulfurized gypsum can be recycled to produce calcium carbonate for reuse as a desulfurizing agent, while producing ammonium sulfate as a byproduct fertilizer.

[0004] 2NH3·H2O+CO2+CaSO4=CaCO3↓+(NH4)2SO4+H2O (1);

[0005] The chemical reaction process of gypsum particles being converted into calcium carbonate can be analyzed using the two-film theory. The conversion process of calcium sulfate to calcium carbonate is related to the solubility of calcium carbonate, the pH value of the reaction slurry, and the concentration of ammonium sulfate in the reaction slurry. In a single-stage reaction system, due to the gradual increase in the concentration of ammonium sulfate, the forward reaction rate of reaction (1) weakens, and the purity of the carbonate product cannot reach the target of greater than 92% or even higher. At the same time, the flue gas will carry the ammonia gas volatilized from the slurry out of the reaction system, causing ammonia escape greater than the current power plant's standard of 8 mg / Nm³. 3 The standard. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a multi-stage series system and process for producing calcium carbonate from desulfurized gypsum in an ammonia-environment environment. In this system, the purified flue gas after desulfurization and dust removal is passed into a desulfurized gypsum slurry for a secondary reaction in an ammonia-water environment. The desulfurized gypsum is then reprocessed into calcium carbonate for reuse as a desulfurizing agent. This not only improves the purity of the calcium carbonate product but also solves the problem of ammonia escape.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides a multi-stage series system for producing calcium carbonate from ammonia-environmentally desulfurized gypsum, comprising a gypsum reaction tower, a tail gas purification tower, a tail gas deep purification tower, a gypsum slurry preparation system, and a flue gas source, wherein...

[0009] Along the flow direction of the gypsum slurry, the gypsum slurry preparation system, the tail gas deep purification tower, the tail gas purification tower and the gypsum reaction tower are connected in series.

[0010] The ammonia water source is connected to the gypsum reaction tower to supply ammonia water to the gypsum reaction tower;

[0011] Along the direction of exhaust gas flow, the gypsum reaction tower, the exhaust gas purification tower, and the exhaust gas deep purification tower are connected in series.

[0012] The flue gas source is connected to the slurry pools of the gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower, respectively, for introducing flue gas into them.

[0013] The upper part of the gypsum reaction tower, the tail gas purification tower and the tail gas deep purification tower are all equipped with a slurry spraying layer. The slurry spraying layer is connected to the slurry pool through a circulation pipe and is located above the tail gas inlet.

[0014] 2NH3·H2O+CO2+CaSO4=CaCO3↓+(NH4)2SO4+H2O (1)

[0015] Reaction (1) is a complex gas-liquid-solid three-phase reaction. CO2 in the flue gas diffuses into the slurry and reacts with ammonia. Gypsum and calcium sulfate particles dissolve into the slurry to form calcium ions and carbonate ions. The carbonate ions and calcium ions form calcium carbonate (the solubility of calcium carbonate is lower than that of calcium sulfate, so it drives reaction (1) to the right) precipitation.

[0016] The CO2 content in the flue gas is typically 10%–15%. A large amount of other ineffective gases (gases that do not participate in the reaction) will carry the NH3 volatilized from the slurry out of the reaction system. From an experimental perspective, the concentration of NH3 carried out exceeds 4000 mg / Nm³. 3 (0.527% by volume), if left untreated, it would far exceed the power plant ammonia slip of 8 mg / Nm³. 3 The standard. Therefore, it is necessary not only to ensure that reaction (1) continues to react to the right, but also to ensure that other means are added to deal with the excessive ammonia tail gas.

[0017] In addition, studies have shown that the concentration of ammonia in the slurry affects the solubility of calcium sulfate. Within the range of 15 to 35°C, ammonia inhibits the dissolution of gypsum particles, reduces the dissolution rate of gypsum, and thus inhibits the reaction (1) from proceeding to the right.

[0018] If a single T1 tower is used for the reaction, the amount of ammonia water required will be excessive. This is because a lot of ammonia will volatilize, a lot of ammonia will be carried away by the flue gas, and ammonia slip will be high (the ammonia slip measured in the experiment reached 14420 mg / Nm³). 3On the other hand, the excessive ammonia concentration inhibits the dissolution of gypsum particles, which slows down the reaction rate of reaction (1) to the right and inhibits the progress of reaction (1) to the right. Within a certain period of time, the purity of calcium carbonate cannot reach 92% (in the experiment, the purity of calcium carbonate can reach 83-88% after 6 hours of slurry reaction, but there is still a lot of calcium sulfate residue, which affects the purity of calcium carbonate). Therefore, it is necessary to use a multi-stage reaction tower in series to improve the purity of calcium carbonate products.

[0019] Based on the above theory, on the one hand, the solid content of the slurry in the T1 tower of this invention is the lowest (actually controlled at 25±5%). At this time, adding high-concentration ammonia water (such as 18-20% concentration ammonia water) to the T1 tower can also play a good role in diluting the ammonia concentration, thereby ensuring that the reaction (1) proceeds to the right, thus ensuring that the purity of calcium carbonate is greater than 92%. On the other hand, the solid content of the T2 and T3 towers is relatively high (actually controlled at 45±5%). Since the amount of ammonia gas processed by these two towers is relatively small, the concentration of ammonia dissolved in the slurry is also not high, which can also ensure that the reaction (1) proceeds to the right, which is equivalent to a pre-reaction relative to the T1 tower.

[0020] The slurry spray layer of each tower is located above the tail gas inlet. After the tail gas enters the tail gas purification tower and the tail gas deep purification tower, it directly contacts and reacts with the sprayed slurry, which can effectively recover ammonia in the tail gas, thereby reducing the ammonia content in the tail gas and preventing ammonia from escaping.

[0021] In some embodiments, a slurry solid-liquid separation device is connected to the bottom of the gypsum reaction tower. After the slurry reaction in the gypsum reaction tower is completed, the slurry is discharged to the slurry solid-liquid separation device for solid-liquid separation to recover the generated calcium carbonate.

[0022] Preferably, the slurry solid-liquid separation device includes, but is not limited to, a sedimentation device, a filter press, a centrifugal separator, a hydrocyclone, or a combination thereof.

[0023] In some embodiments, a slurry stirring device is installed in the gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower. The slurry stirring device is used to stir the slurry to ensure its uniformity. On the one hand, it improves the uniformity of contact between the slurry and ammonia and carbon dioxide, and on the other hand, it prevents solid particles in the slurry from clogging the nozzles during the circulating spraying process.

[0024] In some embodiments, the gypsum slurry preparation system includes a gypsum storage silo, a gypsum metering and unloading device, and a gypsum slurry preparation tank. The gypsum storage silo is located above the gypsum slurry preparation tank and is connected to the gypsum slurry preparation tank through the gypsum metering and unloading device.

[0025] Preferably, the gypsum slurry preparation tank is equipped with a gypsum slurry stirring device.

[0026] In some embodiments, a chimney is also included, which is connected to the exhaust gas outlet of the deep purification tower for discharging the clean flue gas from the recovered ammonia.

[0027] Secondly, the present invention provides a process for producing calcium carbonate from a multi-stage series ammonia-environment desulfurization gypsum, comprising the following steps:

[0028] The fresh gypsum slurry prepared by the gypsum slurry preparation system flows sequentially through the tail gas deep purification tower, the tail gas purification tower and the gypsum reaction tower, and is circulated and sprayed in each tower for reaction.

[0029] The flue gas is fed into the gypsum reaction tower, the tail gas purification tower and the tail gas deep purification tower to participate in the reaction;

[0030] Ammonia water is first added to the gypsum reaction tower to react with the gypsum slurry and carbon dioxide in the flue gas to produce calcium carbonate. Other gases in the flue gas carry ammonia during the discharge process, forming tail gas rich in ammonia. This part of the tail gas is passed into the tail gas purification tower to react with the circulating sprayed slurry to recover the ammonia in the tail gas.

[0031] The ammonia-containing exhaust gas formed in the exhaust gas purification tower is introduced into the exhaust gas deep purification tower, where it reacts with the circulating spray slurry to further recover the ammonia in the exhaust gas.

[0032] In some embodiments, the slurry temperature in the gypsum reaction tower is 35-50°C; the slurry temperature in the tail gas purification tower is 30-45°C; and the slurry temperature in the tail gas deep purification tower is 30-45°C.

[0033] In some embodiments, the solid content of the slurry in the gypsum reaction tower is not higher than 40%, the solid content of the slurry in the tail gas purification tower is not higher than 50%, and the solid content of the slurry in the tail gas deep purification tower is not higher than 50%.

[0034] In some embodiments, the pH value of the slurry in the gypsum reaction tower is 7.5 to 8.5, the pH value of the slurry in the tail gas purification tower is 6.3 to 6.9, and the pH value of the slurry in the tail gas deep purification tower is 6 to 6.6.

[0035] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0036] 1) The desulfurization gypsum has been recycled and utilized, and the unusable desulfurization gypsum currently dumped can be disposed of on a large scale; while the desulfurization gypsum has been recycled, the utilization of CO2 in the flue gas has been fully utilized, and carbon fixation has been achieved. It can also be used as a carbon fixation technology; the reaction (1) continues to proceed efficiently to the right, and the purity of calcium carbonate products is improved; the multi-stage series scheme of reaction tower and purification tower can effectively solve the problem of ammonia escape.

[0037] 2) The multi-stage series design efficiently realizes the functions of each device. The gypsum reaction system 1 focuses on the efficient metathesis of desulfurized gypsum in ammonia and CO2 environments, generating calcium carbonate and ammonium sulfate. The tail gas purification system 1 focuses on removing unreacted NH3 from the gypsum reaction system 1 that escapes into the tail gas. The deep tail gas purification system 3 further absorbs NH3 from the tail gas, ensuring that the NH3 concentration in the tail gas emissions is ≤8 mg / Nm³. 3 ; After being connected in series, it can ensure that the reaction (1) proceeds to the right with relatively high efficiency and the purity of calcium carbonate as a product reaches more than 92%;

[0038] 3) The pH values ​​of the gypsum reaction system 1, tail gas purification system 2, and tail gas deep purification system 3 are reasonably configured. The gypsum reaction system 1 is alkaline to promote the desulfurization gypsum metathesis reaction rate and conversion efficiency, while the tail gas purification system 2 and tail gas deep purification system 3 are acidic to efficiently and deeply remove NH3 from the tail gas.

[0039] 4) Each series unit can be standardized, modularized, and scaled up to achieve continuous industrial production of desulfurized gypsum. Attached Figure Description

[0040] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0041] Figure 1 This is a schematic diagram of the overall structure of a multi-stage series ammonia-environment desulfurization gypsum system for producing calcium carbonate, according to an embodiment of the present invention.

[0042] Among them, 1-gypsum reaction system; 101-NH3-containing exhaust gas inlet fan; 102-first slurry circulation pump; 103-first slurry circulation valve; 104-first slurry spray layer; 105-slurry solid-liquid separation device; 106-slurry discharge pump; 107-gypsum reaction tower; 108-first slurry stirring device; 109-CO2-containing flue gas booster fan;

[0043] 2-Exhaust gas purification system; 201-Second slurry mixing device; 202-CO2-containing flue gas booster fan; 203-First slurry delivery pump; 204-Exhaust gas purification tower; 205-Second slurry spray layer; 206-Second slurry circulation valve; 207-Second slurry circulation pump;

[0044] 3-Deep purification system for exhaust gas; 301-Third slurry mixing device; 302-CO2-containing flue gas booster fan; 303-Second slurry conveying pump; 304-Deep purification tower for exhaust gas; 305-Third slurry spray layer; 306-Third slurry circulation valve; 307-Third slurry circulation pump;

[0045] 4-Gypsum slurry preparation system; 401-Gypsum storage silo; 402-Gypsum metering and unloading device; 403-Gypsum slurry preparation tank; 404-Gypsum slurry mixing device; 405-Gypsum slurry delivery pump;

[0046] 5-Ammonia dosing system; 501-Ammonia tank; 502-Ammonia pump;

[0047] ① CO2-containing flue gas inlet; ② NH3-containing tail gas inlet; ③ Process water inlet; ④ Clean flue gas. Detailed Implementation

[0048] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0049] The present invention will be further described below with reference to the embodiments.

[0050] like Figure 1 As shown, a multi-stage series ammonia-environment desulfurization gypsum system for producing calcium carbonate includes a gypsum reaction system 1, a tail gas purification system 2, a tail gas deep purification system 3, a gypsum slurry preparation system 4, and an ammonia water dosing system 5.

[0051] The gypsum reaction system 1 includes an NH3-containing exhaust gas inlet fan 101, a first slurry circulation pump 102, a first slurry circulation valve 103, a first slurry spray layer 104, a slurry solid-liquid separation device 105, a slurry discharge pump 106, a gypsum reaction tower 107, a first slurry stirring device 108, and a CO2-containing flue gas booster fan 109.

[0052] The exhaust gas purification system 2 includes a second slurry stirring device 201, a CO2-containing flue gas booster fan 202, a slurry conveying system 203, an exhaust gas purification tower 204, a second slurry spray layer 205, a second slurry circulation valve 206, and a second slurry circulation pump 207.

[0053] The exhaust gas deep purification system 3 includes a third slurry stirring device 301, a CO2-containing flue gas booster fan 302, a second slurry conveying pump 303, an exhaust gas deep purification tower 304, a third slurry spray layer 305, a third slurry circulation valve 306, and a third slurry circulation pump 307.

[0054] The gypsum slurry preparation system 4 includes a gypsum storage silo 401, a gypsum metering and unloading system 402, a gypsum slurry preparation tank 403, a gypsum slurry mixing device 404, and a gypsum slurry delivery pump 405.

[0055] The ammonia dosing system 5 includes an ammonia tank 501 and an ammonia pump 502.

[0056] The exhaust outlet of the gypsum reaction system 1 is connected to the inlet of the exhaust gas purification system 2, and the exhaust outlet of the exhaust gas purification system 2 is connected to the inlet of the exhaust gas deep purification system 3.

[0057] The pH value of the slurry inside gypsum reaction tower 107 is 7.5–8.5;

[0058] The pH value of the slurry inside the exhaust gas purification tower 204 is 6.3–6.9;

[0059] The pH value of the slurry inside the 304 deep purification tower for exhaust gas is 6-6.6;

[0060] The pH value of the slurry in the tail gas deep purification tower 304 is not higher than the pH value of the slurry in the tail gas purification tower 204, and the pH value of the slurry in the tail gas purification tower 204 is not higher than the pH value of the slurry in the gypsum reaction tower 107.

[0061] The slurry temperature inside gypsum reaction tower 107 is 35-50℃;

[0062] The slurry temperature inside the exhaust gas purification tower 204 is 30-45℃;

[0063] The slurry temperature inside the 304 deep exhaust gas purification tower is 30-45℃.

[0064] The solid content of the slurry inside gypsum reaction tower 107 shall not exceed 40%;

[0065] The solid content of the slurry inside the exhaust gas purification tower 204 shall not exceed 50%.

[0066] The solid content of the slurry inside the 304 deep purification tower for exhaust gas shall not exceed 50%.

[0067] The solid content of the slurry in the tail gas deep purification tower 304 is not lower than the solid content of the slurry in the tail gas purification tower 204, and the solid content of the slurry in the tail gas purification tower 204 is not lower than the solid content of the slurry in the gypsum reaction tower 107.

[0068] The slurry level inside gypsum reaction tower 107 shall not be less than 2m;

[0069] The slurry level inside the exhaust gas purification tower 204 shall not be less than 2m.

[0070] The slurry level inside the 304 deep purification tower for exhaust gas shall not be less than 2m.

[0071] The number of spray layers in the first slurry spray layer 104 shall not be less than 2;

[0072] The number of spray layers in the second slurry spray layer 205 shall not be less than one;

[0073] The number of spray layers in the third slurry spray layer 305 shall not be less than one;

[0074] The slurry solid-liquid separation device 105 is not limited to using sedimentation systems, filter press systems, centrifugal systems, hydrocyclones and their combinations; the gypsum metering and unloading device 402 is not limited to using belt scales, weighing fluidizing tanks, variable frequency airlock feeders, variable frequency screw conveyors, etc.

[0075] Material flow:

[0076] (1) CO2-containing flue gas

[0077] CO2-containing flue gas enters the system of this invention through inlet ① in three separate paths. After being pressurized by CO2-containing flue gas booster fan 109, it enters gypsum reaction tower 107 to replenish the CO2 required for the desulfurized gypsum reaction. After being pressurized by CO2-containing flue gas booster fan 202, it enters tail gas purification tower 204, which on the one hand replenishes the CO2 required for the desulfurized gypsum in tail gas purification tower 204 and accelerates the absorption of NH3, and on the other hand maintains the pH value in tail gas purification tower 204. After being pressurized by CO2-containing flue gas booster fan 302, it enters tail gas purification tower 304, which on the one hand replenishes the CO2 required for the desulfurized gypsum in tail gas purification tower 304 and accelerates the absorption of NH3, and on the other hand maintains the pH value in tail gas purification tower 304.

[0078] (2) Exhaust gas containing NH3 and exhaust gas from complex reactions

[0079] The NH3-containing exhaust gas enters the gypsum reaction tower 107 through inlet ②. Under the action of spraying, some of the NH3 is washed away. The NH3-containing exhaust gas that is not washed away, along with the NH3 volatilized from the unreacted ammonia water in the gypsum reaction tower 107 and the incompletely reacted CO2-containing flue gas, mix to form a complex reaction exhaust gas, which enters the exhaust gas purification tower 204. Under the action of acidic slurry spraying in 204, most of the NH3 is removed. Then, it enters the exhaust gas deep purification tower 304, where the remaining NH3 is removed under the action of acidic slurry spraying, ensuring that the ammonia slip concentration is ≤8mg / Nm³. 3 .

[0080] (3) Ammonia water

[0081] Before entering the first slurry circulation pump 102 in the gypsum reaction system 1, the ammonia water in the ammonia water tank 501 is pressurized by the ammonia water pump 502 and used to absorb CO2 and adjust the pH value of the gypsum slurry.

[0082] (4) Desulfurized gypsum

[0083] The desulfurized gypsum in the gypsum storage silo 401 enters the gypsum slurry preparation tank 403 after passing through the gypsum metering and unloading device 402. It is mixed with process water to prepare a gypsum slurry with a certain solid content. In order to prevent gypsum sedimentation, the gypsum slurry stirring device 404 is required to continuously stir it.

[0084] (5) Gypsum grout

[0085] The slurry that has completed the reaction in the gypsum reaction tower 107 is pressurized by the slurry discharge pump 106 and enters the slurry solid-liquid separation device 105. After solid-waste separation, calcium carbonate solid and ammonium sulfate solution are formed.

[0086] To ensure the slurry level in the gypsum reaction tower 107, the gypsum slurry from the tail gas purification tower 204 in the tail gas purification system 2 enters the gypsum reaction tower 107 via the first slurry transfer pump 203.

[0087] Similarly, to maintain the slurry level in the exhaust gas purification tower 204, the gypsum slurry in the exhaust gas deep purification system 3 enters the exhaust gas purification tower 204 via the second slurry transfer pump 303. Alternatively, the gypsum slurry prepared in the gypsum slurry preparation system 4 can also enter the exhaust gas purification tower 204 via the gypsum slurry transfer pump 405.

[0088] To ensure the liquid level in the exhaust gas deep purification tower 304, gypsum slurry with a certain solid content prepared by the gypsum slurry preparation system 4 enters the exhaust gas deep purification tower 304 via the gypsum slurry delivery pump 405.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for producing calcium carbonate from a multi-stage series ammonia-environment desulfurization gypsum, characterized in that: Includes the following steps: The fresh gypsum slurry prepared by the gypsum slurry preparation system flows sequentially through the tail gas deep purification tower, the tail gas purification tower and the gypsum reaction tower, and is circulated and sprayed in each tower for reaction. The flue gas is fed into the gypsum reaction tower, the tail gas purification tower and the tail gas deep purification tower to participate in the reaction; Ammonia water is first added to the gypsum reaction tower to react with the gypsum slurry and carbon dioxide in the flue gas to produce calcium carbonate. Other gases in the flue gas carry ammonia during the discharge process, forming tail gas rich in ammonia. This part of the tail gas is passed into the tail gas purification tower to react with the circulating sprayed slurry to recover the ammonia in the tail gas. The ammonia-containing exhaust gas formed in the exhaust gas purification tower is introduced into the exhaust gas deep purification tower, where it reacts with the circulating spray slurry to further recover the ammonia in the exhaust gas. The solid content of the slurry in the gypsum reaction tower shall not exceed 40%, the solid content of the slurry in the tail gas purification tower shall not exceed 50%, and the solid content of the slurry in the tail gas deep purification tower shall not exceed 50%. The pH value of the slurry in the gypsum reaction tower is 7.5~8.5, the pH value of the slurry in the tail gas purification tower is 6.3~6.9, and the pH value of the slurry in the tail gas deep purification tower is 6~6.

6.

2. The process for the production of calcium carbonate from ammonia- environment desulfurization gypsum according to claim 1, characterized in that: The slurry temperature in the gypsum reaction tower is 35-50℃; the slurry temperature in the tail gas purification tower is 30-45℃; and the slurry temperature in the tail gas deep purification tower is 30-45℃.

3. A system for producing calcium carbonate from a multi-stage series ammonia-environment desulfurization gypsum, performing the process described in any one of claims 1-2, characterized in that: It includes a gypsum reaction tower, a tail gas purification tower, a tail gas deep purification tower, a gypsum slurry preparation system, and a flue gas source, among which, Along the flow direction of the gypsum slurry, the gypsum slurry preparation system, the tail gas deep purification tower, the tail gas purification tower and the gypsum reaction tower are connected in series. The ammonia water source is connected to the gypsum reaction tower to supply ammonia water to the gypsum reaction tower; Along the direction of exhaust gas flow, the gypsum reaction tower, the exhaust gas purification tower, and the exhaust gas deep purification tower are connected in series. The flue gas source is connected to the slurry pools of the gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower, respectively, for introducing flue gas into them. The upper part of the gypsum reaction tower, the tail gas purification tower and the tail gas deep purification tower are all equipped with a slurry spraying layer. The slurry spraying layer is connected to the slurry pool through a circulation pipe and is located above the tail gas inlet.

4. The system for producing calcium carbonate from ammonia-environment desulfurization gypsum in a multi-stage series configuration according to claim 3, characterized in that: The bottom of the gypsum reaction tower is connected to a slurry solid-liquid separation device.

5. The multi-stage, series ammonia-environmental desulfurized gypsum system for producing calcium carbonate according to claim 4, characterized in that: The slurry solid-liquid separation device includes, but is not limited to, a sedimentation device, a filter press, a centrifugal separator, a hydrocyclone, or a combination thereof.

6. The multi-stage series ammonia-environmental desulfurized gypsum system for producing calcium carbonate according to claim 3, characterized in that: The gypsum reaction tower, the tail gas purification tower, and the tail gas deep purification tower are all equipped with slurry stirring devices.

7. The multi-stage series ammonia-environmental desulfurized gypsum system for producing calcium carbonate according to claim 3, characterized in that: The gypsum slurry preparation system includes a gypsum storage silo, a gypsum metering and unloading device, and a gypsum slurry preparation tank. The gypsum storage silo is located above the gypsum slurry preparation tank and is connected to the gypsum slurry preparation tank through the gypsum metering and unloading device.

8. The system for producing calcium carbonate from ammonia-environment desulfurization gypsum in a multi-stage series configuration according to claim 7, characterized in that: The gypsum slurry preparation tank is equipped with a gypsum slurry stirring device.

9. The multi-stage, series ammonia-environmental desulfurized gypsum system for producing calcium carbonate according to claim 3, characterized in that: It also includes a chimney, which is connected to the exhaust outlet of the deep exhaust gas purification tower.

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