System for producing ammonium bicarbonate by ammonia process
By using a shell-and-tube heat exchanger for pre-cooling and multi-stage water washing and demisting in the ammonia decarbonization process, the problems of water balance and particulate matter exceeding the standard in the decarbonization tower were solved, achieving efficient carbon dioxide absorption and resource utilization of ammonium bicarbonate, and reducing ammonia escape and environmental impact.
Patent Information
- Application Number
- CN202422063874.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-26
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-08-26
AI Technical Summary
During the ammonia decarbonation process, a large amount of condensate is generated when the decarbonation tower produces ammonium bicarbonate solution, which causes the decarbonation tower to lose water balance. At the same time, the saturated ammonium bicarbonate solution produces problems such as excessive particulate matter and ammonia escape during the absorption process.
The saturated flue gas after desulfurization is pre-cooled using a shell-and-tube heat exchanger. Combined with multi-stage water washing and segmented absorption technology, the flue gas, after being cooled by the shell-and-tube heat exchanger, enters the decarbonization tower. Ammonia water is used to absorb carbon dioxide to generate ammonium bicarbonate solution. The flue gas is then treated by a combined demister and a multi-stage demister to ensure the effective capture of particulate matter and ammonia.
The decarbonization tower water balance problem was solved, the excessive amount of crystallized particulate matter and ammonia escape were reduced, the utilization rate of ammonia was improved, efficient carbon dioxide absorption and resource utilization were achieved, and environmental impact was reduced.
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Figure CN223170663U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of flue gas treatment, in particular to a system for producing ammonium bicarbonate by an ammonia method. Background Technique
[0002] Under the global trend of carbon emission reduction, the capture, storage and utilization of carbon dioxide have become one of the most popular research directions at present. The chemical absorption method is the most widely used technology for post-combustion capture of carbon dioxide in flue gas so far. Common chemical absorbents include hot potassium carbonate solution, alkanolamine solution and ammonia water solution. However, compared with hot potassium carbonate and alkanolamine solutions, ammonia water as an absorbent has the advantages of less corrosion, relatively lower regeneration energy consumption, the ability to achieve comprehensive removal of multiple pollutants, and the production of ammonium bicarbonate by-products to reduce operating costs. Therefore, it has broad application prospects in CO2 emission reduction.
[0003] At present, when decarbonizing the desulfurized saturated flue gas, the moisture content in the desulfurized saturated flue gas is relatively high, and a large amount of water will be precipitated during the absorption process in the decarbonization tower, resulting in an imbalance in the decarbonization process water; and problems such as excessive particulate matter and ammonia escape will occur during the absorption process of the ammonium bicarbonate saturated solution in the ammonia-based decarbonization process system. Summary of the Utility Model
[0004] The technical problem to be solved by the utility model is to provide a system for producing ammonium bicarbonate by an ammonia method, which can solve the problem that a large amount of condensed water is generated while ammonium bicarbonate solution is generated in the absorption tower during the ammonia-based decarbonization process, resulting in an imbalance in the decarbonization tower and thus the inability to saturate ammonium bicarbonate, as well as problems such as excessive particulate matter and ammonia escape during the absorption process of the ammonium bicarbonate saturated solution.
[0005] In order to solve the above technical problems, the technical solution of the utility model is as follows:
[0006] A system for producing ammonium bicarbonate by the ammonia method, comprising a shell-and-tube heat exchanger, a condensate pipeline, a decarbonization tower, a first absorption spray pump, a first-stage absorption spray layer, a second-stage absorption spray layer, a demister, a combined demister, a saturated ammonium bicarbonate transfer pump, a second absorption spray pump, an absorption liquid tank, a saturated ammonium bicarbonate transfer pipeline, a hydrocyclone, a water washing pump, a process water tank, a demineralized water tank, a demineralized water pump, a compression cooler, a cooling and crystallization tank, a crystal slurry pump, a swirling liquid return pipeline, a centrifuge, a dryer, a silo and a packaging machine; the lower part of the decarbonization tower has a flue gas inlet, and the upper part has a flue gas outlet; in the decarbonization tower, a first-stage absorption spray layer, a second-stage absorption spray layer, a demister and a combined demister are sequentially arranged from bottom to top; the inlet of the shell side of the shell-and-tube heat exchanger is used for introducing the saturated flue gas after desulfurization, and the outlet is communicated with the flue gas inlet; the condensate pipeline is arranged on the shell side of the shell-and-tube heat exchanger; the inlet of the first absorption spray pump is communicated with the lower part of the decarbonization tower, and the outlet is communicated with the first-stage absorption spray layer; the inlet of the second absorption spray pump is communicated with the lower part of the absorption liquid tank, and the outlet is communicated with the second-stage absorption spray layer; the inlet of the water washing pump is communicated with the process water tank, and the outlet is communicated with the demister; the inlet of the demineralized water pump is communicated with the demineralized water tank, and the outlet is communicated with the combined demister; the inlet of the saturated ammonium bicarbonate transfer pump is communicated with the lower part of the decarbonization tower, and the outlet is communicated with the inlet of the cooling and crystallization tank through the saturated ammonium bicarbonate transfer pipeline; the compression cooler is used for providing a refrigeration source for the cooling and crystallization tank; the upper parts of the cooling and crystallization tank and the hydrocyclone are communicated with the absorption liquid tank through the swirling liquid return pipeline; the inlet of the crystal slurry pump is communicated with the lower part of the cooling and crystallization tank, and the outlet is communicated with the inlet of the hydrocyclone; the lower discharge port of the hydrocyclone is connected with the inlet of the centrifuge, the discharge port of the centrifuge is connected with the inlet of the dryer, the outlet of the dryer is connected with the inlet of the silo, and the outlet of the silo is connected with the inlet of the packaging machine.
[0007] Preferably, it further comprises a refrigerating machine for providing a cold source for the shell-and-tube heat exchanger, and the cold source of the refrigerating machine is used for being introduced into the tube side of the circulating shell-and-tube heat exchanger for circulating heat exchange.
[0008] Preferably, the dryer adopts a low-temperature dryer.
[0009] Preferably, two-stage or multi-stage absorption is adopted in the decarbonization tower to control ammonia escape.
[0010] Preferably, the condensate pipeline adopts a pipeline with a steam trap.
[0011] Adopting the above technical solutions, the following advantages are achieved:
[0012] 1. Before the desulfurized saturated flue gas enters the decarbonization tower, it first enters a shell-and-tube heat exchanger to cool the flue gas, causing a large amount of moisture to precipitate from the desulfurized saturated flue gas, solving the engineering problem that a large amount of condensed water is generated while ammonium bicarbonate is formed in the absorption tower during the ammonia-based decarbonization process, resulting in the inability of ammonium bicarbonate to reach saturation, that is, solving the problem of the imbalance of the decarbonization tower's water balance.
[0013] 2. The present utility model adopts multi-stage water washing and demisting, which can ensure that fine particles in the air are fully captured and removed, thereby greatly reducing the content of crystalline particulate matter in the discharged gas to effectively solve the problem of excessive crystalline particulate matter. And the decarbonization tower adopts two-stage or multi-stage absorption to more precisely control the ammonia escape amount, reduce unnecessary ammonia loss, and at the same time ensure the effective absorption of carbon dioxide. This segmented absorption method not only improves the utilization rate of ammonia but also reduces the impact on the environment, achieving a more efficient decarbonization effect.
[0014] 3. In the present utility model, the ammonium bicarbonate-containing solution after decarbonization is subjected to cold crystallization treatment to obtain ammonium bicarbonate crystals, realizing the resource utilization of carbon dioxide in industrial flue gas. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 is a schematic structural diagram of the present utility model;
[0016] In the figure:
[0017] 1 - Desulfurized saturated flue gas, 2 - Shell-and-tube heat exchanger, 3 - Condensate pipeline, 4 - Flue gas inlet, 5 - Decarbonization tower, 6 - First absorption spray pump, 7 - First-stage absorption spray layer, 8 - Second-stage absorption spray layer, 9 - Demister, 10 - Combined demister, 11 - Flue gas outlet, 12 - Saturated ammonium bicarbonate transfer pump, 13 - Second absorption spray pump, 14 - Absorption liquid tank, 15 - Saturated ammonium bicarbonate transfer pipeline, 16 - Hydrocyclone, 17 - Water washing pump, 18 - Process water tank, 19 - Desalted water tank, 20 - Desalted water pump, 21 - Compression cooler, 22 - Cooling crystallization tank, 23 - Crystal slurry pump, 24 - Cyclone liquid return pipeline, 25 - Centrifuge, 26 - Dryer, 27 - Bunker, 28 - Packing machine, 29 - Refrigerator. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0018] The following further describes the specific embodiments of the present utility model with reference to the drawings. It should be noted here that the description of these embodiments is for helping to understand the present utility model but does not constitute a limitation to the present utility model. In addition, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.
[0019] In the prior art, when the shell-and-tube heat exchanger 2 conducts heat exchange, one fluid enters from the connecting pipe of the head, flows inside the tubes, and flows out from the outlet pipe at the other end of the head, which is called the tube side; the other fluid enters from the nozzle of the shell and flows out from another nozzle on the shell, which is called the shell side.
[0020] As shown in the Figure 1 accompanying drawing, a system for producing ammonium bicarbonate by the ammonia method includes a shell-and-tube heat exchanger 2, a condensate pipeline 3, a decarbonization tower 5, a first absorption spray pump 6, a first-stage absorption spray layer 7, a second-stage absorption spray layer 8, a demister 9, a combined demister 10, a saturated ammonium bicarbonate transfer pump 12, a second absorption spray pump 13, an absorption liquid tank 14, a saturated ammonium bicarbonate transfer pipeline 15, a hydrocyclone 16, a water wash pump 17, a process water tank 18, a desalted water tank 19, a desalted water pump 20, a compression cooler 21, a cooling and crystallization tank 22, a crystal slurry pump 23, a cyclone liquid return pipeline 24, a centrifuge 25, a dryer 26, a storage bin 27 and a packaging machine 28; the lower part of the decarbonization tower 5 has a flue gas inlet 4, and the upper part has a flue gas outlet 11; inside the decarbonization tower 5, a first-stage absorption spray layer 7, a second-stage absorption spray layer 8, a demister 9 and a combined demister 10 are arranged in sequence from bottom to top; the inlet of the shell side of the shell-and-tube heat exchanger 2 is used to introduce the desulfurized saturated flue gas 1, and the outlet is communicated with the flue gas inlet 4; the condensate pipeline 3 is arranged on the shell side of the shell-and-tube heat exchanger 2; the inlet of the first absorption spray pump 6 is communicated with the lower part of the decarbonization tower 5, and the outlet is communicated with the first-stage absorption spray layer 7; the inlet of the second absorption spray pump 13 is communicated with the lower part of the absorption liquid tank 14, and the outlet is communicated with the second-stage absorption spray layer 8; the inlet of the water wash pump 17 is communicated with the process water tank 18, and the outlet is communicated with the demister 9; the inlet of the desalted water pump 20 is communicated with the desalted water tank 19, and the outlet is communicated with the combined demister 10; the inlet of the saturated ammonium bicarbonate transfer pump 12 is communicated with the lower part of the decarbonization tower 5, and the outlet is communicated with the inlet of the cooling and crystallization tank 22 through the saturated ammonium bicarbonate transfer pipeline 15; the compression cooler 21 is used to provide a refrigeration source for the cooling and crystallization tank 22; the upper part of the cooling and crystallization tank 22 and the upper part of the hydrocyclone 16 are communicated with the absorption liquid tank 14 through the cyclone liquid return pipeline 24; the inlet of the crystal slurry pump 23 is communicated with the lower part of the cooling and crystallization tank 22, and the outlet is communicated with the inlet of the hydrocyclone 16; the lower discharge port of the hydrocyclone 16 is connected to the inlet of the centrifuge 25, the discharge port of the centrifuge 25 is connected to the inlet of the dryer 26, the outlet of the dryer 26 is connected to the inlet of the storage bin 27, and the outlet of the storage bin 27 is connected to the inlet of the packaging machine 28.
[0021] As a further improved technical solution of this embodiment, it further includes a refrigerator 29 for providing a cold source to the shell-and-tube heat exchanger 2. The cold source of the refrigerator 29 is used to be introduced into the tube side of the circulating shell-and-tube heat exchanger 2 for circulating heat exchange, so as to realize the cooling of the desulfurized saturated flue gas 1 and condense the water vapor in the desulfurized saturated flue gas 1. Obviously, other cold source methods can also be used to supply the cold source of the circulating shell-and-tube heat exchanger 2.
[0022] As a preferred technical solution of this embodiment, the dryer 26 is preferably a low-temperature dryer to ensure that a large amount of ammonium bicarbonate solid does not decompose during the drying process.
[0023] As a preferred technical solution of this embodiment, the decarbonization tower 5 adopts two-stage or multi-stage absorption to control ammonia slip.
[0024] As a preferred technical solution of this embodiment, the condensate pipeline 3 adopts a pipeline with a water seal structure (not shown in the figure) to prevent the flue gas from escaping from the condensate pipeline 3. Obviously, the condensate pipeline 3 can also adopt a pipeline with a steam trap to achieve gas-liquid separation and prevent the flue gas from escaping from the condensate pipeline 3.
[0025] The specific working method is as follows: The saturated flue gas 1 after desulfurization is introduced into the shell-and-tube heat exchanger 2 for heat exchange and temperature reduction. The condensed water in the flue gas after heat exchange is discharged through the condensed water pipeline 3. The flue gas after heat exchange and temperature reduction enters the decarbonization tower 5. At the bottom of the decarbonization tower 5, there is a carbon dioxide absorption liquid (ammonia water). The absorption liquid at the bottom of the decarbonization tower 5 is pumped by the first absorption spray pump 6 to the first-stage absorption spray layer 7 for downward spraying, and reacts with the rising flue gas to produce ammonium bicarbonate. The absorption liquid is pumped by the second absorption spray pump 13 to the second-stage absorption spray layer 8 for downward spraying, and continues to react with the continuously rising flue gas to produce ammonium bicarbonate to reduce the carbon dioxide in the flue gas. The absorbed flue gas continues to rise. Process water is pumped by the water washing pump 17 to the demister 9 to remove most of the entrained liquid droplets. Then, it passes through the combined demister 10 for water washing to remove the free ammonia volatilized during the decarbonization process. The demineralized water in the demineralized water tank 19 is pumped by the demineralized water pump 20 to the combined demister 10 to remove the soluble particulate matter in the flue gas. After that, the flue gas is discharged through the flue gas outlet 11. At the same time, the saturated ammonium bicarbonate slurry formed by the absorption of carbon dioxide in the flue gas by ammonia water at the bottom of the decarbonization tower 5 is transported by the saturated ammonium bicarbonate transfer pump 12 through the saturated ammonium bicarbonate transfer pipeline 15 to the cooling crystallization tank 22. The overflow liquid of the cooling crystallization tank 22 returns to the absorption liquid tank 14 through the cyclone liquid return pipeline 24. The cooling crystallization tank 22 exchanges heat with the compression cooler 21 for temperature reduction, so that the cooling crystallization tank 22 cools and crystallizes to precipitate ammonium bicarbonate crystals. The ammonium bicarbonate crystal slurry is sent to the hydrocyclone 16 by the crystal slurry pump 23 for solid-liquid separation. The separated low-temperature liquid returns to the absorption liquid tank 14 through the cyclone liquid return pipeline 24. The absorption liquid tank 14 is connected to the bottom of the decarbonization tower 5, and the carbon dioxide absorption liquid can flow. The ammonium bicarbonate solid is centrifuged by the centrifuge 25, dried by the low-temperature dryer 26 to remove the free moisture, and then enters the storage bin 27, and then is packaged and sold by the packaging machine 28.
[0026] Ammonium bicarbonate is a nitrogen fertilizer that is most easily adsorbed by the soil. It does not contain harmful intermediate products and final decomposition products, and long-term application will not affect the soil quality. It is one of the safest nitrogen fertilizer varieties. Given the importance of chemical fertilizers in increasing the yield of agricultural products, the present utility model can remove carbon dioxide while producing ammonium bicarbonate chemical fertilizer. The present utility model has important significance for the recycling of resources by using ammonia water to remove carbon dioxide in the flue gas and convert it into ammonium bicarbonate.
[0027] In the present utility model, the desulfurized saturated flue gas is first introduced into the shell-and-tube heat exchanger 2 to cool down and a large amount of water is precipitated. Inside the shell-and-tube heat exchanger 2, the desulfurized saturated flue gas 1 is cooled from 55 - 60 °C to 23 - 30 °C. The cooled desulfurized flue gas enters the decarbonization tower 5, where carbon dioxide is absorbed by ammonia water to generate a solution containing ammonium bicarbonate. The decarbonized flue gas utilizes the hierarchical treatment principle of the combined demister 10. First, the ammonia mist formed by the free ammonia volatilized during the decarbonization process is removed through the ammonia mist eliminator, and then a large amount of water mist and soluble particulate matter entrained in the gas-liquid are removed through the demister. Finally, particulate matter with a particle size ≥ 5 μm is removed by the wire mesh. The above ammonia mist eliminator, demister, and wire mesh constitute the combined demister. Obviously, the combined demister can also adopt other common combined forms in the decarbonization tower. If the particle size of the particulate matter in the flue gas ≤ 3 μm, the wet electrostatic demister can be used to replace the water demister and the wire mesh demister. Finally, the flue gas after decarbonization can meet the emission requirements.
[0028] The above has described in detail the embodiments of the present utility model in conjunction with the accompanying drawings, but the present utility model is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present utility model, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present utility model.
Claims
1. A system for producing ammonium bicarbonate by the ammonia method, comprising a shell-and-tube heat exchanger (2), a condensate water pipeline (3), a decarbonization tower (5), a first absorption spray pump (6), a first-stage absorption spray layer (7), a second-stage absorption spray layer (8), a demister (9), a combined demister (10), a saturated ammonium bicarbonate transfer pump (12), a second absorption spray pump (13), an absorption liquid tank (14), a saturated ammonium bicarbonate transfer pipeline (15), a hydrocyclone (16), a water washing pump (17), a process water tank (18), a demineralized water tank (19), a demineralized water pump (20), a compression cooler (21), a cooling and crystallization tank (22), a crystal slurry pump (23), a cyclone liquid return pipeline (24), a centrifuge (25), a dryer (26), a storage bin (27) and a packaging machine (28); the lower part of the decarbonization tower (5) is provided with a flue gas inlet (4), and the upper part is provided with a flue gas outlet (11); in the decarbonization tower (5), a first-stage absorption spray layer (7), a second-stage absorption spray layer (8), a demister (9) and a combined demister (10) are sequentially arranged from bottom to top; characterized in that: The inlet of the shell side of the shell-and-tube heat exchanger (2) is used to introduce the desulfurized saturated flue gas (1), and the outlet is communicated with the flue gas inlet (4); the condensate water pipeline (3) is arranged on the shell side of the shell-and-tube heat exchanger (2); the inlet of the first absorption spray pump (6) is communicated with the lower part of the decarbonization tower (5), and the outlet is communicated with the first-stage absorption spray layer (7); the inlet of the second absorption spray pump (13) is communicated with the lower part of the absorption liquid tank (14), and the outlet is communicated with the second-stage absorption spray layer (8); the inlet of the water washing pump (17) is communicated with the process water tank (18), and the outlet is communicated with the demister (9); the inlet of the desalted water pump (20) is communicated with the desalted water tank (19), and the outlet is communicated with the combined demister (10); the inlet of the saturated ammonium bicarbonate delivery pump (12) is communicated with the lower part of the decarbonization tower (5), and the outlet is communicated with the inlet of the cooling crystallization tank (22) through the saturated ammonium bicarbonate delivery pipeline (15); the compression cooler (21) is used to provide a refrigeration source for the cooling crystallization tank (22); the upper part of the cooling crystallization tank (22) and the upper part of the hydrocyclone (16) are communicated with the absorption liquid tank (14) through the cyclone liquid return pipeline (24); the inlet of the crystal slurry pump (23) is communicated with the lower part of the cooling crystallization tank (22), and the outlet is communicated with the inlet of the hydrocyclone (16); the lower discharge port of the hydrocyclone (16) is connected with the inlet of the centrifuge (25), the discharge port of the centrifuge (25) is connected with the inlet of the dryer (26), the outlet of the dryer (26) is connected with the inlet of the storage bin (27), and the outlet of the storage bin (27) is connected with the inlet of the packaging machine (28).
2. The ammonium bicarbonate production system by the ammonia method according to claim 1, characterized in that: It further includes a refrigerating machine (29) for providing a cold source for the shell-and-tube heat exchanger (2), and the cold source of the refrigerating machine (29) is used to be introduced into the tube side of the circulating shell-and-tube heat exchanger (2) for circulating heat exchange.
3. The ammonium bicarbonate production system by the ammonia method according to claim 1, characterized in that: The dryer (26) adopts a low-temperature dryer.
4. The ammonium bicarbonate production system by the ammonia method according to claim 1, characterized in that: Two-stage or multi-stage absorption is adopted in the decarbonization tower (5) to control ammonia escape.
5. The ammonium bicarbonate production system by the ammonia method according to claim 1, characterized in that: The condensate water pipeline (3) adopts a pipeline with a steam trap.