Method and apparatus for producing ammonium bicarbonate in an ammonia-based decarbonation system

Abstract

An apparatus and method for producing ammonium bicarbonate in an ammonia-based decarbonation system is provided. The apparatus includes a cooling functional zone operable to cool a process gas, an ammonium bicarbonate production zone operable to produce ammonium bicarbonate, a carbon dioxide absorption zone operable to absorb carbon dioxide from the process gas via multi-stage absorption, and an ammonia removal functional zone operable to remove ammonia from the decarbonated process gas, in which absorbent ammonia for carbon dioxide removal is mainly added to the carbon dioxide absorption zone. Through the zone control of ammonium bicarbonate production, CO2 absorption and ammonia removal, the efficiency of decarbonation absorption can be improved and ammonia leakage can be reduced. Meanwhile, the carbon dioxide in the flue gas can be utilized for the production of ammonium bicarbonate as a nitrogen fertilizer.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to and the benefit of Chinese Patent Application No. 202210553353.9, filed on May 20, 2022, the disclosure of which is incorporated herein by reference in its entirety. This application relates to environmental protection. In particular, this application relates to a method and apparatus for producing ammonium bicarbonate in an ammonia-based decarbonation system. [Background technology]

[0002] At present, the efficiency of waste gas treatment in various industrial enterprises is generally low, or the waste gas is only discharged into the atmosphere after desulfurization and dust removal, resulting in the high CO 2 Large amounts of greenhouse gases such as CO2 are released into the environment, resulting in a series of environmental problems such as accelerated global warming. 2 Finding a way to treat the gas is one of the urgent problems for all countries. Ammonium bicarbonate is a NH3 gas that is easily soluble in water, easily decomposed, and applicable to a variety of crops and soils. 4 HCO 3 It is a fast-acting nitrogen fertilizer with the molecular formula of ammonium bicarbonate. Carbon dioxide is one of the raw materials for preparing ammonium bicarbonate. 2 By processing the gas into ammonium bicarbonate, CO 2 In addition to reducing or eliminating the problem of directly releasing ammonium bicarbonate into the atmosphere, ammonium bicarbonate fertilizer can also be prepared.

[0003] China Patent Application No. 201010125082.4 is CO 2 A manufacturing method for synthesizing ammonium bicarbonate fertilizer using waste gas is disclosed. After exhaust gas is dedusted and desulfurized, the CO 2The process uses countercurrent contact of waste gas with concentrated ammonia water to produce ammonium bicarbonate, recovers the ammonia gas from the previous process through an ammonia recovery tower, and releases the remaining waste gas directly into the atmosphere. In this process, concentrated ammonia water and CO for absorption are used. 2 Ammonium bicarbonate can be produced by countercurrent contact with the contained gas, but the temperature does not decrease, and the production of ammonium bicarbonate and CO 2 Since zone control of absorption is not performed in principle, the absorption efficiency is low and ammonia leakage is high. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent Application No. 201010125082.4 Summary of the Invention

[0005] The present inventors have made intensive research to overcome the problems of low absorption efficiency and serious ammonia leakage in the existing ammonia-based decarbonation system and effectively increase the production of the by-product ammonium bicarbonate. As a result, the high absorption efficiency and effective ammonia leakage control of the ammonia-based decarbonation process and the increase in ammonium bicarbonate production are achieved by providing multiple functional zones and reducing the amount of ammonium bicarbonate produced, CO 2 It has been found that this can be achieved by zone control of absorption and ammonia removal. Hence the present invention has been made.

[0006] The object of the present invention is therefore an apparatus for producing ammonium bicarbonate in an ammonia-based decarbonation system, the apparatus comprising: a cooling function zone operable to cool the process gas; an ammonium bicarbonate production zone operable to produce ammonium bicarbonate; a carbon dioxide absorption zone operable to absorb carbon dioxide from the process gas via multi-stage absorption; an ammonia removal functional zone operable to remove ammonia from the decarbonated process gas; The object of the present invention is to provide an apparatus in which the carbon dioxide absorption zone is primarily added with absorbing ammonia for carbon dioxide removal.

[0007] A further object of the present invention is a method for producing ammonium bicarbonate in an ammonia-based decarbonation system, the method comprising: receiving a desulfurized process gas; The desulfurized process gas is a cooling functional zone configured to cool the process gas; an ammonium bicarbonate production zone configured to produce an ammonium bicarbonate solution / slurry; a multi-stage carbon dioxide absorption zone configured to absorb carbon dioxide in the desulfurized process gas; and and sequentially flowing the decarbonated process gas through an ammonia removal functional zone configured to remove ammonia in the decarbonated process gas; The carbon dioxide absorption zone is primarily charged with absorbing ammonia for carbon dioxide removal. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic flow chart of an apparatus / method according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In a first aspect, the disclosure provides an apparatus for producing ammonium bicarbonate in an ammonia based decarbonation system, the apparatus comprising a cooling functional zone operable to cool a process gas, an ammonium bicarbonate production zone operable to produce ammonium bicarbonate, a carbon dioxide absorption zone operable to absorb carbon dioxide from the process gas via multi-stage absorption, and an ammonia removal functional zone operable to remove ammonia from the decarbonated process gas, wherein the carbon dioxide absorption zone is primarily charged with absorbing ammonia for carbon dioxide removal.

[0010] As used herein, the phrase "the carbon dioxide absorption zone is primarily charged with absorbing ammonia for carbon dioxide removal" means that more than 60 wt.%, such as more than 65 wt.%, such as more than 80 wt.%, such as more than 90 wt.%, such as more than 98 wt.%, or such as 100 wt.%, of the total absorbing ammonia used for carbon dioxide removal in the method / apparatus of the present disclosure is introduced into the carbon dioxide absorption zone and / or fed into the stream to the carbon dioxide absorption zone.

[0011] In some embodiments, the amount of ammonia added to the ammonium bicarbonate production zone is less than the amount added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone, or no ammonia is added to the ammonium bicarbonate production zone.

[0012] In some embodiments, the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than the amount of ammonia added to other stages of the carbon dioxide absorption zone, or no ammonia is added to the first stage of the carbon dioxide absorption zone. Preferably, the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than 20% of the total amount of ammonia added in the process.

[0013] In some embodiments, the amount of ammonia added to the final stage of the carbon dioxide absorption zone is less than the amount of ammonia added to the upstream stage of the carbon dioxide absorption zone, or no ammonia is added to the final stage of the carbon dioxide absorption zone. Preferably, the amount of ammonia added to the final stage of the carbon dioxide absorption zone is 80% by weight or less of the amount added to the upstream stage of the carbon dioxide absorption zone, such as 50% by weight or less, for example 30% by weight or less.

[0014] In some embodiments, solid ammonium bicarbonate is produced from ammonium bicarbonate produced in the ammonium bicarbonate production zone by a work-up system and the ammonium bicarbonate mother liquor is returned to the first stage carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone.

[0015] In some embodiments, the cooling functional zone, the ammonium bicarbonate production zone, the carbon dioxide absorption zone and the ammonia removal functional zone may be combined into one or more towers, with equipment / components that allow gas to pass between the functional zones.

[0016] In a second aspect, the present disclosure provides a method for producing ammonium bicarbonate in an ammonia-based decarbonation system, the method comprising: receiving a desulfurized process gas; The desulfurized process gas is a cooling functional zone configured to cool the desulfurized process gas; an ammonium bicarbonate production zone configured to produce an ammonium bicarbonate solution / slurry; a multi-stage carbon dioxide absorption zone configured to absorb carbon dioxide in the desulfurized process gas; and and sequentially flowing the decarbonated process gas through an ammonia removal functional zone configured to remove ammonia in the decarbonated process gas; A method is provided in which the carbon dioxide absorption zone is primarily charged with absorbing ammonia for carbon dioxide removal.

[0017] In some embodiments of the process, the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than the amount of ammonia added to other stages of the carbon dioxide absorption zone, or no ammonia is added to the first stage of the carbon dioxide absorption zone. Preferably, the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than 20% of the total amount of ammonia added in the process.

[0018] In some embodiments of the process, the amount of ammonia added to the final stage of the carbon dioxide absorption zone is less than the amount of ammonia added to the previous stage of the carbon dioxide absorption zone, or no ammonia is added to the final stage of the carbon dioxide absorption zone. Preferably, the amount of ammonia added to the final stage of the carbon dioxide absorption zone is 80% by weight or less of the amount added to the previous stage of the carbon dioxide absorption zone, such as 50% by weight or less, for example 30% by weight or less.

[0019] In some embodiments of the process, solid ammonium bicarbonate is produced from ammonium bicarbonate produced in the ammonium bicarbonate production zone by a work-up system and the ammonium bicarbonate mother liquor is returned to the first stage absorption zone immediately adjacent to the ammonium bicarbonate production zone.

[0020] In some embodiments of the method, the cooling functional zone cools the process gas to a temperature of between 10 and 30 degrees Celsius.

[0021] In some embodiments of the method, the cooling functional zone is provided with at least one layer of circulating liquid distributor.

[0022] In some embodiments of the present process, the ammonium bicarbonate production zone is provided with at least one layer of gas-liquid distributor, which may be selected from the group consisting of gas bubble distributors, liquid distribution spray distributors, and combinations thereof.

[0023] In some embodiments of the process, the carbon dioxide absorption zone is provided with at least two or more layers of circulating liquid distributors.

[0024] In some embodiments of the method, the ammonia removal functional zone is provided with at least one layer of circulating liquid distributor. The circulating liquid used in the ammonia removal functional zone is preferably water or an acidic solution.

[0025] In some embodiments of the method, relative to the flow direction of the process gas, the circulating liquid in the rear stage of the carbon dioxide absorption zone overflows into the front stage of the carbon dioxide absorption zone, and the circulating liquid in the first stage of the carbon dioxide absorption zone overflows into the ammonium bicarbonate production zone.

[0026] As will be appreciated by those skilled in the art, water may be used as the medium for each of the circulating / spraying liquids in the present process.

[0027] Exemplary embodiments of the apparatus / method according to the principles of the present disclosure are described below with reference to the accompanying drawings, which form a part of this disclosure. 2 The contained process gas 1 first enters a cooling functional zone 2 where the gas is brought into countercurrent contact with a circulating liquid for cooling, which is circulated by a cooling circulating pump 3 and cooled by a heat exchanger 4 .

[0028] The cooled gas enters ammonium bicarbonate production zone 5 where the gas is countercurrently contacted with circulating liquid for reaction to produce ammonium bicarbonate, and the circulating liquid is circulated by circulating pump 9. The process gas exiting ammonium bicarbonate production zone 5 enters first stage carbon dioxide absorption zone 7. First stage carbon dioxide absorption zone 7 is separated from ammonium bicarbonate production zone 5 by liquid collector 6 which allows the passage of gas, and the circulating liquid in first stage carbon dioxide absorption zone 7 flows into ammonium bicarbonate production zone 5.

[0029] In the first stage carbon dioxide absorption zone 7, the gas is countercurrently contacted with the circulating liquid for reaction to produce ammonium carbonate or ammonium carbamate, and the circulating liquid is circulated by a circulating pump 10. The first stage carbon dioxide absorption zone 7 is separated from the second stage carbon dioxide absorption zone 8 by a liquid collector 6 that allows the passage of gas, and the circulating liquid in the second stage carbon dioxide absorption zone 8 flows into the first stage carbon dioxide absorption zone 7. The mother liquor from the solid-liquid separation in the ammonium bicarbonate post-treatment system is returned to the first stage carbon dioxide absorption zone 7.

[0030] The gas passing through the first stage carbon dioxide absorption zone 7 enters the second stage carbon dioxide absorption zone 8 where the gas is countercurrently contacted with a circulating liquid for reaction to further produce ammonium carbonate or ammonium carbamate, and the circulating liquid is circulated by a circulating pump 11.

[0031] The gas passing through the second stage carbon dioxide absorption zone 8 enters the third stage carbon dioxide absorption zone 13 where the gas is countercurrently contacted with a circulating liquid for reaction to further produce ammonium carbonate or ammonium carbamate, and the circulating liquid is circulated by a circulating pump 12.

[0032] Ammonia 22 is supplied via lines to the first stage carbon dioxide absorption zone 7 and the second stage carbon dioxide absorption zone 8.

[0033] The gas passing through the third stage carbon dioxide absorption zone 13 for further processing enters a water wash ammonia removal functional zone 14 and then an acid wash ammonia removal functional zone 24 where the gas is countercurrently contacted with water and an acidic ammonium sulfate solution, respectively, to absorb the free ammonia, the water being circulated by a circulation pump 16. The ammonia-removed process gas 15 is discharged, optionally after a further water wash.

[0034] The circulating liquid in the ammonium bicarbonate production zone 5 is pumped via ammonium bicarbonate discharge pump 23 to the ammonium bicarbonate crystallizer 17 and then enters the solid-liquid separator 18. The resulting solid is sent to a charger 19 to produce solid ammonium bicarbonate 20. The resulting mother liquor is returned to the first stage carbon dioxide absorption zone 7.

[0035] Example 1 The apparatus shown in FIG. 1 was used in Example 1. 2 The process gas 1 first enters the cooling function zone 2, where the process gas is brought into countercurrent contact with a circulating liquid for cooling, and the circulating liquid is circulated by a cooling circulation pump 3 and cooled by a heat exchanger 4. The circulating liquid is water, and components entrained in the process gas are mixed into the circulating liquid during the circulation process, so that the circulating liquid contains components such as ammonium sulfate, which is a by-product of the above-mentioned ammonia-based desulfurization.

[0036] The gas cooled to 25°C entered ammonium bicarbonate production zone 5 where the process gas was countercurrently contacted with circulating liquid for reaction to produce ammonium bicarbonate, the circulating liquid being circulated by circulating pump 9. The process gas leaving ammonium bicarbonate production zone 5 entered first stage carbon dioxide absorption zone 7 which was separated from ammonium bicarbonate production zone 5 by liquid collector 6 which allowed the passage of gas, and the circulating liquid in first stage carbon dioxide absorption zone 7 flowed into ammonium bicarbonate production zone 5.

[0037] In the first stage carbon dioxide absorption zone 7, the gas was countercurrently contacted with the circulating liquid for reaction to produce ammonium carbonate or ammonium carbamate, and the circulating liquid was circulated by a circulating pump 10. The first stage carbon dioxide absorption zone 7 was separated from the second stage carbon dioxide absorption zone 8 by a liquid collector 6 that allowed the passage of gas, and the circulating liquid in the second stage carbon dioxide absorption zone 8 flowed into the first stage carbon dioxide absorption zone 7. The mother liquor from the solid-liquid separation in the ammonium bicarbonate post-treatment system was returned to the first stage carbon dioxide absorption zone 7.

[0038] The gas passing through the first stage carbon dioxide absorption zone 7 enters the second stage carbon dioxide absorption zone 8, where the gas is countercurrently contacted with a circulating liquid for reaction to further produce ammonium carbonate or ammonium carbamate, and the circulating liquid is circulated by a circulating pump 11.

[0039] The gas passing through the second stage carbon dioxide absorption zone 8 enters the third stage carbon dioxide absorption zone 13, where the gas is countercurrently contacted with a circulating liquid for reaction to further produce ammonium carbonate or ammonium carbamate, and the circulating liquid is circulated by a circulating pump 12.

[0040] Ammonia 22 was supplied via lines to the first stage carbon dioxide absorption zone 7 and the second stage carbon dioxide absorption zone 8. The amount of ammonia supplied to the first stage was 10 wt %, and the amount of ammonia supplied to the second stage was 90 wt %.

[0041] The gas that passed through the third-stage carbon dioxide absorption zone 13 entered the water-washing ammonia removal functional zone 14, and then entered the acid-washing ammonia removal functional zone 24, where the gas was brought into countercurrent contact with water and an ammonium sulfate solution, respectively, to absorb free ammonia, and the water was circulated by a circulation pump 16. The process gas 15 after ammonia removal was discharged. The water-washing ammonia removal functional zone 14 used water as the circulating liquid, and since components entrained in the process gas were mixed into the circulating liquid during the circulation process, the circulating liquid contained components such as ammonium bicarbonate, which was a by-product of the above-mentioned ammonia-based decarbonation.

[0042] The circulating liquid in the ammonium bicarbonate production zone 5 was sent to the ammonium bicarbonate crystallizer 17 via the ammonium bicarbonate discharge pump 23 and then entered the solid-liquid separator 18. The resulting solid was sent to the charger 19 to produce solid ammonium bicarbonate 20. The resulting mother liquor was returned to the first stage carbon dioxide absorption zone 7.

[0043] The decarbonation uses 99.6% liquid ammonia as the absorbent, and the parameters of process gas 1 are shown in the table below.

[0044] [Table 1]

[0045] The parameters of the cooled flue gas are given in the table below.

[0046] [Table 2]

[0047] The main parameters after treatment by the decarbonation absorption tower are shown in the table below.

[0048] [Table 3]

[0049] The main parameters after treatment with the ammonia scrubber are given in the table below.

[0050] [Table 4]

[0051] Comparative Example 1 Compared with Example 1, only the ammonia addition method was different. Ammonia was supplied to the ammonium hydrogen carbonate production zone, the first stage carbon dioxide absorption zone, the second stage carbon dioxide absorption zone and the third stage carbon dioxide absorption zone, and the amounts of ammonia supplied to the four stages were equivalent.

[0052] The amount of ammonia supplied to the ammonium hydrogen carbonate production zone reached 25%, which made it difficult to produce ammonium hydrogen carbonate in the solution, and ammonium hydrogen carbonate crystals could not be obtained. The amount of ammonia supplied to the third stage carbon dioxide absorption zone reached 25%, which significantly increased ammonia leakage from the carbon dioxide absorption zone (the concentration of ammonia entrained in the process gas after treatment in the carbon dioxide absorption zone reached 6000 ppm). Therefore, the ammonia removal load of the rear stage water washing ammonia removal function zone 14 and acid washing ammonia removal function zone 24 increased.

[0053] The main parameters of the gas after decarbonation are shown in the table below.

[0054] [Table 5] [Explanation of symbols]

[0055] In FIG. 1, the reference numerals have the following meaning: 1 process gas, 2 cooling function zone, 3 cooling circulation pump, 4 heat exchanger, 5 ammonium bicarbonate production zone, 6 liquid collector, 7 first stage carbon dioxide absorption zone, 8 second stage carbon dioxide absorption zone, 9 ammonium bicarbonate production zone circulation pump, 10 first stage carbon dioxide absorption zone circulation pump, 11 second stage carbon dioxide absorption zone circulation pump, 12 third stage carbon dioxide absorption zone circulation pump, 13 third stage carbon dioxide absorption zone, 14 ammonia removal function zone water wash section, 15 decarbonated gas, 16 ammonia removal function zone water wash circulation pump, 17 ammonium bicarbonate crystallizer, 18 solid-liquid separator, 19 filling machine, 20 solid ammonium bicarbonate, 21 mother liquor return pipe, 22 ammonia, 23 ammonium bicarbonate discharge pump, 24 ammonia removal function zone acid wash section, 25 ammonium sulfate solution from ammonia-based desulfurization, 26 solution returning to ammonia-based desulfurization.

Claims

1. 1. An apparatus for producing ammonium bicarbonate in an ammonia-based decarbonation system, the apparatus comprising: a cooling function zone operable to cool the process gas; an ammonium bicarbonate production zone operable to produce ammonium bicarbonate; a carbon dioxide absorption zone operable to absorb carbon dioxide from the process gas via multi-stage absorption; an ammonia removal functional zone operable to remove ammonia from the decarbonated process gas; The carbon dioxide absorption zone is primarily charged with absorbing ammonia for carbon dioxide removal.

2. Features: the amount of ammonia added to the ammonium bicarbonate production zone is less than the amount of ammonia added to a first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone, or no ammonia is added to the ammonium bicarbonate production zone; the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than the amount of ammonia added to other stages of the carbon dioxide absorption zone, or no ammonia is added to the first stage of the carbon dioxide absorption zone, preferably the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than 20% of the total amount of ammonia added; the amount of ammonia added to the final stage of the carbon dioxide absorption zone is less than the amount of ammonia added to the initial stage of the carbon dioxide absorption zone, or no ammonia is added to the final stage of the carbon dioxide absorption zone; The apparatus of claim 1 , further comprising at least one of:

3. 2. The apparatus of claim 1, wherein solid ammonium bicarbonate is produced from ammonium bicarbonate produced in the ammonium bicarbonate production zone by a work-up system and ammonium bicarbonate mother liquor is returned to the first stage absorption zone immediately adjacent said ammonium bicarbonate production zone.

4. 2. The apparatus of claim 1, wherein the cooling functional zone, the ammonium bicarbonate production zone, the carbon dioxide absorption zone and the ammonia removal functional zone are combined into one or more towers, and equipment / components allowing gas to pass through are located between the functional zones.

5. 1. A process for producing ammonium bicarbonate in an ammonia-based decarbonation system, the process comprising: receiving a desulfurized process gas; The desulfurized process gas is a cooling functional zone configured to cool the desulfurized process gas; an ammonium bicarbonate production zone configured to produce an ammonium bicarbonate solution / slurry; a multi-stage carbon dioxide absorption zone configured to absorb carbon dioxide in the desulfurized process gas; and and sequentially flowing the decarbonated process gas through an ammonia removal functional zone configured to remove ammonia in the decarbonated process gas; The method wherein the carbon dioxide absorption zone is primarily charged with absorbing ammonia for carbon dioxide removal.

6. Features: the amount of ammonia added to the ammonium bicarbonate production zone is less than the amount of ammonia added to a first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone, or no ammonia is added to the ammonium bicarbonate production zone; the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than the amount of ammonia added to other stages of the carbon dioxide absorption zone, or no ammonia is added to the first stage of the carbon dioxide absorption zone, preferably the amount of ammonia added to the first stage of the carbon dioxide absorption zone immediately adjacent to the ammonium bicarbonate production zone is less than 20% of the total amount of ammonia added; the amount of ammonia added to the final stage of the carbon dioxide absorption zone is less than the amount of ammonia added to the initial stage of the carbon dioxide absorption zone, or no ammonia is added to the final stage of the carbon dioxide absorption zone; The method of claim 5 , comprising at least one of:

7. passing the ammonium bicarbonate produced in the ammonium bicarbonate production zone through a post-treatment system to produce solid ammonium bicarbonate; returning the resulting ammonium bicarbonate mother liquor to a first stage absorption zone immediately adjacent said ammonium bicarbonate production zone; The method of claim 5 further comprising:

8. Features: The cooling functional zone cools the process gas to 10 to 30°C; The cooling function zone is provided with at least one circulating liquid distributor; The ammonium bicarbonate production zone is provided with at least one layer of gas-liquid distributor, preferably the gas-liquid distributor is selected from the group consisting of a gas bubble distributor, a liquid distribution spray distributor and a combination thereof; The carbon dioxide absorption zone is provided with at least one circulating liquid distributor; The ammonia removal functional zone is provided with at least one circulating liquid distributor; The method of claim 5 , comprising at least one of:

9. 6. The method according to claim 5, wherein, relative to the flow direction of the process gas, the circulating liquid of the rear stage of the carbon dioxide absorption zone flows into the front stage of the carbon dioxide absorption zone, and the circulating liquid of the first stage of the carbon dioxide absorption zone flows into the ammonium bicarbonate production zone.

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