Device for producing ammonium bicarbonate by decarburization of flue gas by ammonia process

Abstract

The utility model discloses a device for producing ammonium bicarbonate by decarburization of flue gas by ammonia process, which comprises a flue gas cooling area (1), a carbon dioxide enrichment area (2) and a decarburization separation area (3) which are matched with each other, and the flue gas cooling area (1) comprises an induced draft fan (12), a cooling tower (13) and a cooling circulation system (14); the carbon dioxide enrichment area (2) comprises a water removal tower (21), a booster fan (23), a low-pressure pressure swing adsorption tower (24), a vacuum booster fan (25) and a second cooler (26); the carbon removal separation area (3) comprises a carbon removal tower (31) and an ammonia liquid supply system (34) which are matched with each other; the lower part of a three-stage carbonization section (310) of the carbon removal tower (31) is connected with a thickener (36) and a centrifugal machine (37) through a carbon ammonia liquid discharge pump (35). The device has the advantages that the concentration of discharged smoke dust is effectively reduced, the quality of ammonium bicarbonate mixed salt meets the standard requirements of chemical fertilizers, and the energy-saving effect is obvious.

Description

Technical Field

[0001] The utility model belongs to the technical field of ammonium bicarbonate production, and particularly relates to a device for producing ammonium bicarbonate by flue gas ammonia decarbonation. Background Art

[0002] Carbon capture, utilization and storage technology can convert CO2 into useful products or permanently store it, and is an important method of carbon emission reduction technology. Permanent storage of CO2 has high investment and no benefits, which is not attractive to enterprises. Therefore, CO2 can be converted into useful products to improve economic benefits under certain conditions. At present, one of the main carbon capture technologies is the organic amine method, but this method has problems such as high operating costs, large emissions of three wastes in the system, and difficulty in handling.

[0003] Ammonia decarbonization is a common and mature method for producing ammonium bicarbonate in small nitrogen fertilizers, and it has certain economic benefits. However, although ammonia decarbonization has mature industrial applications in small nitrogen fertilizer production, the industrial flue gas conditions are very different from the conversion gas in small nitrogen fertilizer production, especially the working pressure, gas composition, and carbon dioxide gas concentration. The conversion gas pressure is about 0.4~0.8MPa, the carbon dioxide concentration is about 20~40%V / V, and the temperature is about 20~40℃. The industrial flue gas emission pressure is basically normal pressure, the carbon dioxide concentration is about 10~15%V / V, and the temperature is about 50~150℃. Therefore, the decarbonization process in small nitrogen fertilizer production cannot be directly applied.

[0004] At present, some environmental protection companies have also developed an ammonia decarbonization process that is different from the small nitrogen fertilizer production process. However, due to its low carbon dioxide concentration and large equipment, the ammonia concentration in the exhaust gas after decarbonization is relatively high, and acidified ammonium sulfate must be used to absorb the ammonia in the exhaust gas. Its process must be matched with ammonia desulfurization, which also limits the scope of application of the process. Utility Model Content

[0005] The purpose of the utility model is to solve the problems of poor effect, limited use and high cost of the existing decarbonization process, and to provide a device for producing ammonium bicarbonate by flue gas ammonia decarbonization, which can effectively reduce the concentration of emitted smoke, make the quality of ammonium bicarbonate mixed salt meet the fertilizer standard requirements, reduce the power of the decarbonization vacuum booster fan, and have obvious energy-saving effect.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A device for producing ammonium bicarbonate by flue gas ammonia decarbonization comprises a flue gas cooling zone, a carbon dioxide enrichment zone and a carbon removal separation zone which cooperate with each other.

[0008] The flue gas cooling zone includes an induced draft fan connected to the flue gas duct, which is further connected to the middle and lower part of the cooling tower through a pipeline. The cooling tower is provided with a cooling and cooling circulation system for heat exchange with the flue gas. The top of the cooling tower is connected to the carbon dioxide enrichment zone through a first pipeline.

[0009] The carbon dioxide enrichment zone includes a dewatering tower connected to the first pipeline, the dewatering tower is connected to the booster fan through the second pipeline, and the end of the second pipeline is connected to a group of low-pressure pressure swing adsorption towers, the outlet of each low-pressure pressure swing adsorption tower is connected to the vacuum booster fan through a pipeline, the vacuum booster fan is connected to the second cooler, the outlet pipeline of the second cooler is connected to the third pipeline and the fourth pipeline respectively, and the third pipeline and the fourth pipeline are both connected to the carbon removal separation zone;

[0010] The carbon removal separation zone comprises a carbon removal tower, in which a third-stage carbonization section, a second-stage carbonization section, a first-stage carbonization section and a pickling section are arranged from bottom to top, the third pipeline is connected to the third-stage carbonization section, the fourth pipeline is connected to the first-stage carbonization section, the side wall of the carbon removal tower is connected to a decarbonization circulation pump, and the side wall of the pickling section is connected to a pickling circulation pump;

[0011] The lower part of the pickling section is connected to the ammonia liquid supply system, the outlet end of the ammonia liquid supply system is connected to the inlet area of ​​the decarbonization circulation pump of the secondary carbonization section, the decarbonization circulation pump is connected to the uppermost sieve plate in the primary carbonization section through a pipeline, the lower part of the tertiary carbonization section is connected to the thickener through the carbon-ammonia liquid discharge pump, the thickener is connected to the centrifuge, the centrifuge is respectively connected with a wet ammonium bicarbonate discharge pipe and a mother liquor recovery pipe, the mother liquor recovery pipe is connected to the secondary carbonization section.

[0012] Furthermore, the cooling and temperature reduction circulation system includes a cooling circulation pump, a first cooler, a low-temperature water system, a condensate water tank and a condensate water pump. The cooling circulation pump pumps the low-temperature water at the bottom of the cooling tower to the top of the cooling tower through a circulation pipe. The bottom of the cooling tower is connected to the low-temperature water system through the first cooler, and the side of the cooling tower is connected to the condensate water tank through a pipeline, and the discharge port of the condensate water tank is then connected to the condensate water pump.

[0013] Furthermore, the top of the carbon removal tower is merged with the first pipeline through a recovery pipe, and then leads into a dewatering tower. The dewatering tower is connected to an electric heater and a drain pipe is provided on the top of the dewatering tower to regenerate the tail gas after the dewatering tower is saturated with water and then heated by an electric heater to enrich carbon dioxide. The regenerated waste gas is directly discharged.

[0014] Furthermore, the ammonia liquid supply system includes a dilute ammonia water pump connected to the lower part of the pickling section, the dilute ammonia water pump is connected to the ammonia mixer through a pipeline, the inlet of the ammonia mixer is connected to the external ammonia pipeline, the outlet of the ammonia mixer is connected to the concentrated ammonia water tank through a pipeline, the concentrated ammonia water tank is connected to the concentrated ammonia water pump through a fifth pipeline, and the end of the fifth pipeline is connected to the inlet area of ​​the decarbonization circulation pump of the secondary carbonization section.

[0015] Further, in each of the three carbonization sections in the carbon removal tower, there is more than one set of third coolers and more than one set of sieve plates.

[0016] Further, a fourth cooler is provided in the concentrated ammonia water tank, and a DCD inlet pipe is also connected to the top of the concentrated ammonia water tank for feeding the ammonium bicarbonate stabilizer DCD into the concentrated ammonia water tank for mixing.

[0017] Further, the cooling method in the flue gas cooling zone is direct gas-liquid heat exchange, where low-temperature water cools the raw flue gas, and the flue gas after heat exchange reaches below 20°C.

[0018] Further, after passing through the low-pressure pressure swing adsorption tower, the carbon dioxide in the enriched flue gas reaches more than 40%.

[0019] Further, the pressure of the flue gas after passing through the vacuum booster fan and the second cooler is controlled between 0.15 and 0.25 MPa, and the temperature is controlled between 10 and 20°C.

[0020] In the technical solution of the present utility model, by adopting this process, the discharged dust concentration is less than 1 mg / Nm 3 , the quality of the ammonium bicarbonate mixed salt meets the requirements of the chemical fertilizer standard. At the same time, after concentrating the carbon dioxide concentration in the flue gas by low-pressure pressure swing adsorption, the power of the decarbonization vacuum booster fan is reduced to 1 / 4 of that of the non-concentrating process, and the energy-saving effect is obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of the device for producing ammonium bicarbonate by ammonia method for flue gas decarbonization of the present utility model;

[0022] Figure 2 is a table of the main parameters for producing ammonium bicarbonate by ammonia method for flue gas decarbonization in this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiment

[0023] To make the present utility model more clearly understood, the following further describes a device for producing ammonium bicarbonate by ammonia method for flue gas decarbonization of the present utility model with reference to the accompanying drawings. The specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0024] See Figure 1 , a device for producing ammonium bicarbonate by ammonia method for flue gas decarbonization, including a mutually cooperating flue gas cooling zone 1, a carbon dioxide enrichment zone 2, and a carbon removal and separation zone 3, characterized in that:

[0025] The flue gas cooling zone 1 includes a draft fan 12 connected to the flue gas pipeline 11. The draft fan 12 is further connected to the middle and lower part of a cooling tower 13 through a pipeline. A cooling and temperature reduction circulation system 14 for heat exchange with the flue gas is provided in the cooling tower 13. The top of the cooling tower 13 is connected to the carbon dioxide enrichment zone 2 through a first pipeline 15;

[0026] The cooling and temperature reduction circulation system 14 includes a cooling circulation pump 141, a first cooler 142, a low-temperature water system 143, a condensate water tank 144, and a condensate water pump 145. The cooling circulation pump 141 pumps the low-temperature water at the bottom of the cooling tower to the top of the cooling tower through a circulation pipe. The bottom of the cooling tower 13 is connected to the low-temperature water system 143 through the first cooler 142. The side of the cooling tower 13 is connected to the condensate water tank 144 through a pipeline, and the drain outlet of the condensate water tank 144 is further connected to the condensate water pump 145;

[0027] The carbon dioxide enrichment zone 2 includes a water removal tower 21 connected to the first pipeline 15. The water removal tower 21 is connected to a booster fan 23 through a second pipeline 22, and the end of the second pipeline 22 is connected to a group of low-pressure pressure swing adsorption towers 24. The outlet of each low-pressure pressure swing adsorption tower 24 is connected to a vacuum booster fan 25 through a pipeline. The vacuum booster fan 25 is further connected to a second cooler 26. The outlet pipeline of the second cooler 26 is respectively connected to a third pipeline 27 and a fourth pipeline 28, and both the third pipeline 27 and the fourth pipeline 28 are connected to the carbon removal and separation zone 3;

[0028] The carbon removal and separation zone 3 includes a carbon removal tower 31. Inside the carbon removal tower 31, three-stage carbonization sections 310, two-stage carbonization sections 311, one-stage carbonization sections 312, and an acid pickling section 313 are successively arranged from bottom to top. The third pipeline 27 is connected to the three-stage carbonization section 310, and the fourth pipeline 28 is connected to the one-stage carbonization section 312. Third coolers 314 are connected in all three carbonization sections. Decarbonization circulation pumps 32 are correspondingly connected to the side walls of the carbonization sections of the carbon removal tower 31, and an acid pickling circulation pump 33 is correspondingly connected to the side wall of the acid pickling section 313;

[0029] The lower part of the acid pickling section 313 is connected to an ammonia liquid supply system 34. The ammonia liquid supply system 34 includes a dilute ammonia water pump 341 connected to the lower part of the acid pickling section 313. The dilute ammonia water pump 341 is further connected to an ammonia mixer 342 through a pipeline. The inlet of the ammonia mixer 342 is connected to an external ammonia pipeline 343. The outlet of the ammonia mixer 342 is connected to a concentrated ammonia water tank 344 through a pipeline. A fourth cooler 347 is provided in the concentrated ammonia water tank 344, and a DCD inlet pipe 348 is further connected to the top of the concentrated ammonia water tank 344 for feeding the ammonium bicarbonate stabilizer DCD into the concentrated ammonia water tank for mixing;

[0030] The concentrated ammonia water tank 344 is connected to the concentrated ammonia water pump 346 through the fifth pipeline 345, and the end of the fifth pipeline 345 is connected to the inlet area of the decarbonization circulating pump 32 in the secondary carbonization section 311. The decarbonization circulating pump 32 is then connected to the uppermost sieve plate in the primary carbonization section 312 through a pipeline;

[0031] The lower part of the tertiary carbonization section 310 is connected to the thickener 36 through the ammonium carbamate liquid discharge pump 35. The thickener 36 is then connected to the centrifuge 37. The centrifuge 37 is respectively connected with the wet ammonium bicarbonate discharge pipe 371 and the mother liquor recovery pipe 372, and the mother liquor recovery pipe 372 is then connected to the secondary carbonization section 311.

[0032] The top of the carbon dioxide removal tower 31 is merged with the first pipeline 15 through the recovery pipe 38, and after merging, it is introduced into the water removal tower 21. The water removal tower 21 is connected to the electric heater 29, and the top of the water removal tower 21 is provided with an exhaust pipe 210 for the regeneration of the tail gas after the water removal tower is saturated with water and the carbon dioxide is enriched by heating with the electric heater. The regenerated waste gas is directly exhausted.

[0033] The present utility model uses ammonia or ammonia water as the decarbonization agent, adopts low-pressure pressure swing adsorption to concentrate the carbon dioxide concentration in the flue gas, absorbs the carbon dioxide and ammonium bicarbonate in the flue gas. It uses sulfuric acid as the ammonia removal agent to absorb the ammonia in the tail gas and generate ammonium sulfate.

[0034] The reaction equations are as follows:

[0035] Carbon dioxide dissolves in water: CO2 + H2O → H2CO3;

[0036] Ammonia dissolves in water: NH3 + H2O → NH3H2O, carbonation degree 0%;

[0037] Carbonic acid reacts with ammonia water: H2CO3 + NH3 → NH4HCO3, carbonation degree 200%;

[0038] NH4HCO3 + NH3 → (NH4)2CO3, carbonation degree 100%;

[0039] CO2 + (NH4)2CO3 + H2O → 2NH4HCO3, carbonation degree 200%;

[0040] Dilute sulfuric acid reacts with ammonia: H2SO3 + 2NH3 → (NH4)2SO3.

[0041] In this embodiment, the flue gas flow process is as follows: The raw flue gas enters the bottom of the cooling tower 13 through the induced draft fan 12 and directly exchanges heat with the coolant pumped out by the cooling circulation pump 141. The heat of the raw flue gas exchanged is removed from the system through the cooling water heat exchanger, and the temperature of the raw flue gas drops to between 10 and 20 °C. The low-temperature raw flue gas is dewatered in the dewatering tower 21, pressurized by the booster fan 23, and then enters the low-pressure pressure swing adsorption tower 24. The carbon dioxide is enriched to more than 40%. Then, through the vacuum booster fan 25 and the second cooler 26, the flue gas pressure is controlled between 0.15 and 0.25 MPa, and the temperature is controlled between 10 and 20 °C. The enriched flue gas is divided into two paths and enters the first-stage carbonization section 312 and the third-stage carbonization section 310 for carbonization respectively, and then merges into the second-stage carbonization section 311 for further carbonization absorption. The flue gas after carbonization finally enters the pickling section 313 at the upper part of the carbon removal tower 31. The ammonia in the flue gas after pickling is finally mixed with the cooled raw flue gas for recycling. After the dewatering tower 21 is saturated with water absorption, it is regenerated by heating the tail gas enriched with carbon dioxide through the electric heater 29, and the regenerated waste gas is directly discharged.

[0042] In this embodiment, the ammonia flow process is as follows: The incoming gaseous ammonia or liquid ammonia water is mixed with the dilute ammonia water after washing the flue gas in the ammonia mixer 342, enters the concentrated ammonia water tank 344, and ammonium bicarbonate stabilizer DCD is added. Then, it is added to the inlet area of the decarbonization circulation pump 32 in the second-stage carbonization section 311 through the concentrated ammonia water pump 346 and mixed with the ammonium bicarbonate-ammonium carbonate buffer solution coming from the tower. It is pumped to the top sieve plate in the first-stage carbonization section 312. The solution contacts the high-concentration carbon dioxide flue gas. The carbon dioxide in the flue gas dissolves in water and reacts with the solution. Then, it enters the second-stage carbonization section 311 to further contact and absorb carbon dioxide with the flue gas. Then, part of it enters the third-stage carbonization section 310 to contact and absorb carbon with the high-concentration carbon dioxide flue gas. Finally, the ammonium bicarbonate slurry with a carbonization degree of more than 195% is pumped to the thickener 36 and the centrifuge 37 for liquid-solid separation. The wet ammonium bicarbonate is discharged, and the mother liquor returns to the second-stage carbonization section 311.

[0043] In this embodiment, the sulfuric acid flow process is as follows: Dilute sulfuric acid is added to the pickling pool at the upper part of the carbon removal tower 31. The sulfuric acid reacts with the ammonia gas in the flue gas to form ammonium sulfate, and the ammonium sulfate solution overflows into the first-stage carbonization section 312 and is mixed with the ammonium bicarbonate-ammonium carbonate solution.

[0044] Taking the 50000 Nm 3 / h saturated flue gas after desulfurization of coal-fired flue gas, with a wet content of 11%, a temperature of 48 °C, and CO2 of 14% V / V as an example, its main parameters are as Figure 2 shown. After decarbonization by the device of the present invention, the decarbonization efficiency is 64%, the total emission of dust is less than 1 mg / Nm 3 , and the output of ammonium bicarbonate solid is 14.2 t / h.

[0045] In addition to the above embodiments, the present utility model may also have other embodiments. Any technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope required by the present utility model.

Claims

1. An apparatus for producing ammonium bicarbonate by ammonia-based decarbonization of flue gas, comprising a flue gas cooling zone (1), a carbon dioxide enrichment zone (2) and a carbon decarbonization separation zone (3) which cooperate with each other, characterized in that: The flue gas cooling zone (1) includes a draft fan (12) connected to a flue gas pipeline (11). The draft fan (12) is further connected to the middle and lower part of a cooling tower (13) through a pipeline. A cooling and temperature reduction circulation system (14) for exchanging heat with the flue gas is provided in the cooling tower (13). The top of the cooling tower (13) is connected to the carbon dioxide enrichment zone (2) through a first pipeline (15); The carbon dioxide enrichment zone (2) includes a water removal tower (21) connected to the first pipeline (15). The water removal tower (21) is connected to a booster fan (23) through a second pipeline (22), and the end of the second pipeline (22) is connected to a group of low-pressure pressure swing adsorption towers (24). The outlet of each low-pressure pressure swing adsorption tower (24) is connected to a vacuum booster fan (25) through a pipeline. The vacuum booster fan (25) is further connected to a second cooler (26). The outlet pipeline of the second cooler (26) is respectively connected to a third pipeline (27) and a fourth pipeline (28). Both the third pipeline (27) and the fourth pipeline (28) are connected to the carbon decarbonization separation zone (3); The carbon decarbonization separation zone (3) includes a carbon decarbonization tower (31). Inside the carbon decarbonization tower (31), a three-stage carbonization section (310), a two-stage carbonization section (311), a one-stage carbonization section (312) and a pickling section (313) are successively arranged from bottom to top. The third pipeline (27) is connected to the three-stage carbonization section (310), and the fourth pipeline (28) is connected to the one-stage carbonization section (312). The side wall of the carbonization section of the carbon decarbonization tower (31) is correspondingly connected to a decarbonization circulation pump (32), and the side wall of the pickling section (313) is correspondingly connected to a pickling circulation pump (33); The lower part of the pickling section (313) is connected to an ammonia liquor supply system (34). The outlet end of the ammonia liquor supply system (34) is connected to the inlet area of the decarbonization circulation pump (32) in the two-stage carbonization section (311). The decarbonization circulation pump (32) is further connected to the uppermost sieve plate in the one-stage carbonization section (312) through a pipeline. The lower part of the three-stage carbonization section (310) is connected to a thickener (36) through a carbon ammonia liquor discharge pump (35). The thickener (36) is further connected to a centrifuge (37). A wet ammonium bicarbonate discharge pipe (371) and a mother liquor recovery pipe (372) are respectively connected to the centrifuge (37). The mother liquor recovery pipe (372) is further connected to the two-stage carbonization section (311).

2. The apparatus for producing ammonium bicarbonate by ammonia-based decarbonization of flue gas according to claim 1, characterized in that: The cooling and temperature reduction circulation system (14) includes a temperature reduction circulation pump (141), a first cooler (142), a low-temperature water system (143), a condensate water tank (144), and a condensate water pump (145). The temperature reduction circulation pump (141) pumps the low-temperature water at the bottom of the cooling tower to the top of the cooling tower through a circulation pipe. The bottom of the cooling tower (13) is connected to the low-temperature water system (143) through the first cooler (142). The side of the cooling tower (13) is connected to the condensate water tank (144) through a pipeline, and the discharge port of the condensate water tank (144) is connected to the condensate water pump (145).

3. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 1 or 2, characterized in that: The top of the carbon removal tower (31) converges with the first pipeline (15) through a recovery pipe (38), and after convergence, it is introduced into the water removal tower (21). The water removal tower (21) is connected to an electric heater (29), and an exhaust pipe (210) is provided at the top of the water removal tower (21).

4. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 3, characterized in that: The ammonia liquid supply system (34) includes a dilute ammonia water pump (341) connected to the lower part of the pickling section (313). The dilute ammonia water pump (341) is connected to an ammonia mixer (342) through a pipeline. The inlet of the ammonia mixer (342) is connected to an external ammonia pipeline (343). The outlet of the ammonia mixer (342) is connected to a concentrated ammonia water tank (344) through a pipeline. The concentrated ammonia water tank (344) is connected to a concentrated ammonia water pump (346) through a fifth pipeline (345), and the end of the fifth pipeline (345) is connected to the inlet area of the decarbonization circulation pump (32) in the secondary carbonization section (311).

5. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 3, characterized in that: One or more groups of third coolers (314) and one or more groups of sieve plates are provided in each of the three carbonization sections in the carbon removal tower (31).

6. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 4, characterized in that: A fourth cooler (347) is provided in the concentrated ammonia water tank (344), and a DCD inlet pipe (348) is also connected to the top of the concentrated ammonia water tank (344).

7. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 3, characterized in that: The cooling method in the flue gas cooling area (1) is direct gas-liquid heat exchange. The low-temperature water cools the raw flue gas, and the temperature of the flue gas after heat exchange is below 20°C.

8. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 3, characterized in that: The carbon dioxide in the enriched flue gas reaches more than 40% after passing through the low-pressure pressure swing adsorption tower (24).

9. The device for producing ammonium bicarbonate by flue gas ammonia-based decarbonization according to claim 3, characterized in that: The pressure of the flue gas after passing through the vacuum booster fan (25) and the second cooler (26) is controlled between 0.15 and 0.25 MPa, and the temperature is controlled between 10 and 20°C.

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