Apparatus and method for staged absorption ammonia-based decarbonation

Abstract

A staged absorption ammonia-based decarbonation method using an absorption circulating liquid containing ammonium salt to remove carbon dioxide in the gas, and suppress ammonia leakage while realizing efficient decarbonation through staged liquid composition control and reaction condition control. The staged solution composition control may include concentration gradient control of ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonia, or a combination thereof, which may be characterized by a molar ratio of total ammonia to total CO2. The reaction condition control may include temperature control, pH control, and pressure control. The flue gas enters the decarbonation tower, and through staged absorption, concentration, temperature establishment, and multi-point addition of ammonia, the decarbonation efficiency may be improved, the operating cost of decarbonation may be saved, and ammonia leakage may be controlled.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of Chinese Patent Application No. 202210553874.4, filed on May 19, 2022, the entirety of which is incorporated herein by reference. The present invention relates to the technical field of environmental protection, and in particular to an apparatus and method for step-by-step absorption ammonia-based decarbonation. [Background technology]

[0002] Global warming is an issue that affects the development of all humankind. The main cause of global warming is carbon dioxide. Industrial gases generated by production activities in the chemical industry contain large amounts of carbon dioxide.

[0003] The chemical absorption method using ammonia as the absorption liquid has the characteristics of strong absorption capacity, low corrosion, low regeneration energy consumption, low replenishment cost, not easily decomposed by other components in the flue gas, and simultaneous removal of various acid gas pollutants. Many studies on the chemical absorption method have been conducted by scholars at home and abroad.

[0004] China Patent Publication No. 108144428 proposes a process of section control and multi-point addition of ammonia, which is mainly divided into a pre-scrubbing section, an absorption section and a particulate control section, each of which is provided with multiple spray layers. The pre-scrubbing section cools the flue gas while concentrating the circulating scrubbing liquid in the pre-scrubbing section, and the absorption section absorbs and removes sulfur dioxide in the flue gas. The leakage of ammonia and the generation of aerosols in each section are controlled. Similarly, this method also removes CO from industrial gases. 2 Lack of emission controls to remove

[0005] China Patent No. 101524621 provides a flue gas decarbonation system with stepwise absorption and regeneration, which is composed of an absorption system, a regeneration system and a heat exchange system, and has lower energy consumption than the prior art. However, this system is applicable to a system using ethanolamine as a desulfurization agent, and the energy saving effect is achieved by controlling the multi-stage regeneration liquid return and absorption system.

[0006] Chinese Patent Application No. 200880122376.2 discloses a multi-stage CO2 ion exchange method for treating a flue gas stream. 2 Disclosed is a removal system and method, in which an absorption vessel is used, and the flue gas stream is contacted with an ionic solution containing ammonia at a low temperature of 0-20°C, the solution in the first absorption stage having a higher temperature and a lower ammonia-to-carbon ratio than the solution in the third absorption stage. Ammonia leakage can be reduced by controlling at a low temperature and having a lower temperature in the third stage, but a higher ammonia-to-carbon ratio in the third stage increases ammonia leakage. This process has low decarbonation efficiency, high energy consumption, and serious ammonia leakage. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] China Patent Application Publication No. 108144428 [Patent Document 2] Chinese Patent No. 101524621 [Patent Document 3] Chinese Patent Application No. 200880122376.2 [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an exemplary apparatus in accordance with the principles of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A method is provided for staged absorption ammonia-based decarbonation that uses an absorption circulating liquid containing ammonium salt to remove carbon dioxide in a gas and achieve efficient decarbonation through staged solution composition control and reaction condition control while suppressing ammonia breakthrough.

[0010] At 10-30°C and 1 atm, CO 2 and ammonia react to produce ammonium carbamate and ammonium carbonate as the main products, and this reaction is reversible.

[0011] The overall chemical reaction equation is as follows: [ka]

[0012] In the actual reaction process, there are many intermediate reactions. The general process is as follows: [ka]

[0013] Hydrolysis of ammonium carbamate: [ka]

[0014] NH 3 and H 2 Reaction with O: [ka]

[0015] The ammonium bicarbonate produced by hydrolysis reacts with ammonia to produce ammonium carbonate: [ka]

[0016] Ammonium carbonate absorbs carbon dioxide to form ammonium bicarbonate: [ka]

[0017] From the above reactions, we can see that there are various complex chemical reactions between carbon dioxide and ammonia, most of which are reversible reactions, and the solution composition is complex. 2 To improve the efficiency of the reaction between nitric acid and ammonia, a rational stepwise solution composition control and reaction condition control are required.

[0018] The graded solution composition control may include concentration gradient control of ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonia, or combinations thereof, which may include controlling the total CO 2 It may be characterized by the molar ratio of total ammonia to

[0019] The reaction condition control may include temperature control, pH control, and pressure control.

[0020] The cooled flue gas can be contacted sequentially with an ammonium bicarbonate producing liquid and a decarbonation absorption liquid to achieve synergistic control of ammonium bicarbonate production, ammonium bicarbonate crystallization, carbon dioxide absorption and ammonia breakthrough, where the ammonium bicarbonate producing liquid may be provided with at least one gas-liquid contacting stage to reduce the total CO in the solution. 2 The molar ratio of total ammonia to total CO may range from 1 to 3, preferably from 1 to 2, and the total ammonia may include ammonia and ammonium radicals, and the total CO 2 is free CO 2 and carbonized CO 2 The decarbonation absorption circulation liquid may include at least two stages of gas-liquid contact, and the total CO in the solution in the first stage may include at least two stages of gas-liquid contact. 2The molar ratio of total ammonia to total CO may range from 1.2 to 4, preferably from 1.4 to 3.5, more preferably from 1.6 to 3, and most preferably from 1.8 to 2.5. 2 The molar ratio of total ammonia to total CO in the final solution may be in the range of 1.5 to 4.5, preferably 1.8 to 4, more preferably 2 to 3.5. 2 The molar ratio of total ammonia to may be in the range of 1-3, preferably 1.2-2.8, more preferably 1.5-2.5, and most preferably 1.6-2.

[0021] The gas-liquid contact form of the ammonium hydrogen carbonate production liquid is preferably a spray type, a filling type, or a bubbling type, and the gas-liquid contact form of the decarbonation absorption liquid is preferably a spray type or a filling type.

[0022] The temperature control may be to lower the temperature of the solution through a cold source, and the solution may be in contact with the flue gas to lower the temperature of the flue gas. For the cold source, a refrigerator may be used to prepare cold water, and the cold water may cool the solution through a heat exchanger or coil. The temperature of the ammonium bicarbonate production liquid may be controlled to be in the range of 10 to 30°C, preferably 12 to 28°C, preferably 15 to 25°C, and most preferably 16 to 22°C. In the first stage, the temperature of the decarbonation absorption liquid may be higher than that of the ammonium bicarbonate production liquid. A high solution temperature may be beneficial to reduce investment in cooling equipment. The temperature of the decarbonation absorption liquid between the first stage and the final stage is usually higher than that of the decarbonation absorption liquid in the first stage and the decarbonation absorption liquid in the final stage. In the final stage, the temperature of the decarbonation absorption liquid may be lower than that of the ammonium bicarbonate production liquid, which may control ammonia leakage. Preferably, the temperature of the ammonium bicarbonate production circulation liquid may be controlled to be in the range of 15°C to 25°C. In the first stage, the temperature of the decarbonation absorption circulating liquid may be higher than the temperature of the ammonium bicarbonate production circulating liquid, and in the final stage, the temperature of the decarbonation absorption circulating liquid may be lower than the temperature of the ammonium bicarbonate production circulating liquid.

[0023] pH control may be achieved via the addition of ammonia or solution replacement between stages.

[0024] Ammonia is added mainly to the decarbonation absorption liquid, but may be added to the decarbonation absorption liquid in multiple stages. No or almost no ammonia is added to the ammonium hydrogen carbonate production liquid, and the amount of ammonia added to the decarbonation absorption liquid in the final stage may be less than that of the decarbonation absorption liquid in the previous stage, or no ammonia may be added. Preferably, ammonia is added to the first and second stage decarbonation absorption circulation liquids, and the amount of ammonia added to the second stage decarbonation absorption circulation liquid may account for 80 to 50% by weight (weight percent), preferably 75 to 55% by weight, more preferably 72% to 57% by weight, and most preferably 60 to 65% by weight of the total amount of ammonia added. No ammonia is added to the decarbonation absorption circulation liquid and the ammonium hydrogen carbonate production circulation liquid in the final stage. It is beneficial to control the solution composition, adjust the pH value of the solution, and control ammonia leakage while ensuring the efficiency of decarbonation absorption through the multiple addition of ammonia. In order to ensure the production of ammonium hydrogen carbonate, no or almost no ammonia is added to the ammonium hydrogen carbonate production liquid. The amount of ammonia added to the decarbonated absorption liquid in the final stage may be less than that in the previous stage, or no ammonia may be added, which may suppress ammonia leakage.

[0025] The solution replacement may be performed via overflow or pumping of a pipe for transferring the previous solution to the next solution, and the solution composition and pH value may be controlled. The pH value of the ammonium bicarbonate-producing liquid may be lower than the pH value of the decarbonation absorption liquid, and the ammonium bicarbonate content of the ammonium bicarbonate-producing liquid may be higher than the ammonium bicarbonate content of the decarbonation absorption liquid.

[0026] The pH value of the decarbonated absorbing liquid may be 8.0 or greater, preferably 8.2 or greater, more preferably 8.5 or greater, and most preferably 9.0 or greater.

[0027] Pressure control may be achieved, for example, by providing a control valve or liquid seal in the ammonia-based decarbonation system. If necessary, a control valve or liquid seal device may be provided in the gas line after the decarbonation absorption zone or after the ammonia breakthrough control system to maintain the internal pressure of the system.

[0028] The ammonia based decarbonator may be maintained at atmospheric pressure ±50 kPa, preferably at atmospheric pressure ±40 kPa, more preferably at atmospheric pressure ±30 kPa, and most preferably at atmospheric pressure ±25 kPa.

[0029] An apparatus for staged absorption ammonia-based decarbonation is provided, which may include a decarbonation system, an ammonia breakthrough control system, an ammonium bicarbonate treatment system, an ammonia supply system, and a cooling system.

[0030] The decarbonation system may include a zone control including an ammonium bicarbonate production zone and a decarbonation absorption zone, where the ammonium bicarbonate production zone is provided with at least one stage of gas liquid contactor and the decarbonation absorption zone is provided with at least two stages of gas liquid contactor, with gas-only passing equipment / components provided between the zones and stages.

[0031] One or more demister layers may be provided after the final stage of the decarbonation absorption zone, with the remaining layers optionally being free of one or more demister layers. The demisters may be of the baffle, ridge, packing and screen type, or combinations thereof.

[0032] The ammonia leak control system may include a multi-stage cleaning cycle and may include at least one layer of acidic solution cleaning.

[0033] A cooling system may be used to reduce the temperature of the ammonium bicarbonate production circulating liquid and the decarbonation absorption circulating liquid.

[0034] The ammonium bicarbonate processing system may include an ammonium bicarbonate crystallization facility and a solid-liquid separation facility.

[0035] CO in process gas before decarbonation 2 The content may be in the range of 6 to 50v% (volume percent), preferably 8 to 40v%, and more preferably 10 to 30v%.

[0036] CO in gas after staged absorption ammonia treatment 2 The content may be in the range of 0 to 10v%, preferably 0 to 8v%, and preferably 0 to 6v%.

[0037] Clean flue gas SO 2 is 10mg / Nm 3 Less than 5mg / Nm 3 Less than 2mg / Nm, more preferably 3 It may have the following:

[0038] The ammonia leakage of the clean flue gas may be less than 20 ppm, preferably less than 15 ppm, more preferably less than 10 ppm.

[0039] CO 2 The removal efficiency may be 60% or more, preferably 70% or more, more preferably 80% or more.

[0040] The method may include removing carbon dioxide from the gas using an absorption circulating liquid containing an ammonium salt. The method may include limiting ammonia breakthrough by applying a controlled composition of the circulating liquid to the gas at different stages. Each stage may have controlled reaction conditions.

[0041] The controlled composition is total CO 2 The controlled composition may be characterized by a molar ratio of total ammonia to ammonium carbonate. The controlled composition may include ammonium bicarbonate. The controlled composition may include ammonium carbamate. The controlled composition may include ammonia.

[0042] The method may include cooling the flue gas. The method may include, after cooling, continuously contacting the flue gas with an ammonium bicarbonate-producing circulating liquid. The method may include, after cooling, continuously contacting the flue gas with a decarbonation absorption circulating liquid. The ammonium bicarbonate-producing liquid may be included in at least one stage of gas-liquid contacting. After that stage, the total CO in the ammonium bicarbonate-producing liquid may be 2 The molar ratio of total ammonia to CO may be in the range of 1 to 3. The decarbonated absorbing liquid may be included in at least two stages of gas-liquid contacting. After the first stage, the total CO in the decarbonated absorbing liquid may be 2 The molar ratio of total ammonia to total CO in the decarbonated absorption liquid after the final stage may be in the range of 1.2 to 4. 2 The molar ratio of total ammonia to CO may range from 1 to 3. After any stage occurring between the first and final stage, the total CO in the decarbonated absorption liquid 2 The molar ratio of total ammonia to total CO may be in the range of 1.5 to 4.5. The total ammonia may include ammonia and ammonium radicals. 2 is free CO 2 and carbonized CO 2 may include:

[0043] The gas-liquid contact of the ammonium hydrogen carbonate production liquid may be of the spray type, the filling type or the bubbling type. The gas-liquid contact of the decarbonation absorption liquid may be of the spray type or the filling type.

[0044] The pH value of the ammonium bicarbonate producing liquid may be lower than the pH value of the decarbonated absorbing liquid. The ammonium bicarbonate content of the ammonium bicarbonate producing liquid may be higher than the ammonium bicarbonate content of the decarbonated absorbing liquid.

[0045] The pH value of the decarbonated absorption liquid may be greater than 8.0.

[0046] The method may include adding a first amount of ammonia to the ammonium bicarbonate product liquid. The method may include adding a second amount of ammonia to the decarbonation absorption liquid, the second amount being greater than the first amount. The adding to the decarbonation absorption liquid may include adding less ammonia to the final stage of the decarbonation absorption liquid than is added to the decarbonation absorption liquid in a decarbonation stage prior to the final stage.

[0047] Adding the second amount of ammonia to the decarbonated absorption liquid may include distributing only the second amount of ammonia separately to the multiple stages.

[0048] Contacting the flue gas with the decarbonation absorption circulating liquid may include conducting the contact at atmospheric pressure ±50 kPa.

[0049] The method may include controlling the reaction conditions. The reaction conditions may include one or more of temperature, pH and pressure.

[0050] The method may include sequentially contacting the flue gas with an ammonium bicarbonate production circulating liquid and a decarbonation absorption circulating liquid. The controlling may include reducing a temperature of the ammonium bicarbonate production liquid using a cold source. The controlling may include reducing a temperature of the decarbonation absorption liquid using a cold source.

[0051] The controlling may include adding ammonia to or replacing the ammonium bicarbonate product liquid to control the pH of the ammonium bicarbonate product liquid between stages. The controlling may include adding ammonia to or replacing the decarbonation absorption liquid to adjust the pH of the decarbonation absorption liquid between stages. The controlling may include maintaining contact between the flue gas and the decarbonation absorption liquid at atmospheric pressure using a control valve or a liquid seal rather than a control valve between stages. The contact may reduce the temperature of the flue gas.

[0052] The method may include maintaining the temperature of the ammonium bicarbonate product liquid in the range of 10-30°C.

[0053] The method may include maintaining the decarbonation absorbing liquid at a temperature higher than the temperature of the ammonium bicarbonate-producing liquid in a first stage of contacting the gas with the decarbonation absorbing liquid. The method may include maintaining the decarbonation absorbing liquid at a temperature higher than the temperature of the ammonium bicarbonate-producing liquid in a final stage of contacting the gas with the decarbonation absorbing liquid.

[0054] This method uses a gas concentration of 10 mg / Nm 3 The following SO 2 The method may include releasing the gas with an ammonia breakthrough of 20 ppm or less.

[0055] CO 2 More than 60% CO 2 It may be removed with a removal efficiency.

[0056] CO in process gas before decarbonation 2 The content may be in the range of 6 to 50v% (volume percent). 2 The content may be in the range of 0 to 10% by volume.

[0057] The method may include receiving gas from an ammonia-based desulfurization process.

[0058] The apparatus may include an apparatus for staged absorption ammonia-based decarbonation.

[0059] The apparatus may include a decarbonation system. The apparatus may include an ammonia leak control system. The apparatus may include an ammonium bicarbonate treatment system. The apparatus may include an ammonia supply system. The apparatus may include a cooling system.

[0060] The decarbonation system may include an ammonium bicarbonate production zone. The decarbonation system may include a decarbonation absorption zone. The ammonium bicarbonate production zone may include at least one stage of gas-liquid contacting. The decarbonation absorption zone may include at least two stages of gas-liquid contacting.

[0061] Gas-only passing components may be disposed between the zones. Gas-only passing components may be disposed between the stages.

[0062] The apparatus may include one or more layers of demisters after the final stage of the decarbonation absorption zone. The apparatus may include at least one layer of acid solution wash.

[0063] The ammonia breakthrough control system may include a multi-stage cleaning cycle control. The cooling system may be configured to reduce a temperature of the ammonium bicarbonate product liquid. The cooling system may be configured to reduce a temperature of the decarbonated absorption liquid. The ammonium bicarbonate treatment system may include an ammonium bicarbonate crystallization facility. The ammonium bicarbonate treatment system may include a solid-liquid separation facility.

[0064] The gas treated in the process of the present invention is any suitable gas, preferably ammonia-based desulfurized process gas.

[0065] CO in gas 2 The content is significantly reduced by the stepwise absorption ammonia process of the present invention. Specifically, the CO 2 The content is 6 to 50v%, preferably 8 to 40v%, and more preferably 10 to 30v%.

[0066] CO in gas after the step-by-step absorption ammonia system treatment of the present invention 2 The content is 0 to 10v%, preferably 0 to 8v%, and more preferably 0 to 6v%.

[0067] The process for staged absorption ammonia-based decarbonation protected by the present invention is preferably carried out in an apparatus for staged absorption ammonia-based decarbonation defined by the present invention.

[0068] The beneficial effects of the present invention are mainly reflected in the decarbonation efficiency, ammonia leakage, and the production of ammonium bicarbonate fertilizer (abbreviated as ammonium bicarbonate). The decarbonation efficiency achieved by the method according to the present invention is at least 60%, preferably at least 70%, more preferably at least 80%. After decarbonation, the ammonia leakage is less (800-5000 ppm), which can reduce the load of the ammonia leakage control system, thereby reducing the investment cost and operation cost. The ammonia leakage after passing through the ammonia leakage control system is not more than 20 ppm, preferably 15 ppm, more preferably 10 ppm. The solid content of ammonium bicarbonate in the ammonium bicarbonate production zone is more than 2 wt%, preferably more than 5 wt%, more preferably more than 8 wt%. Meanwhile, the decarbonation device is capable of reducing the amount of pollutant SO 2 Partially absorbed, 10mg / Nm 3 Less than 5mg / Nm 3 Less than 2mg / Nm 3 Less than low SO 2 Concentrations can be obtained. Decarboxylation efficiency = (Q1 × w1 - Q2 × w2) / (Q1 × w1) × 100%

[0069] Q1 is the flow rate (m ) of dry flue gas under standard conditions at the inlet of the decarbonation device. 3 / h), w1 is the volume fraction (%) of carbon dioxide in the flue gas at the inlet of the decarbonation device measured by the meter, and Q2 is the flow rate (m 3 / h), and w1 is the volume fraction (%) of carbon dioxide in the flue gas at the outlet of the decarbonator as measured by the meter.

[0070] SO in gas 2The content can be tested according to HJ629-2011 Fixed Pollution Source Waste Gas-Determination of Sulfur Dioxide-Non-Dispersive Infrared Absorption Method, and CO 2 The content can be tested according to HJ 870-2017 Fixed Pollution Source Waste Gas-Determination of Carbon Dioxide-Non-Dispersive Infrared Absorption Method, NH 3 The content can be tested according to HJ 533-2009 Determination of Ammonia in Ambient Air and Waste Gas-Nesseler Reagent Spectroscopic Analysis.

[0071] Exemplary embodiments of apparatus and methods according to the principles of the present invention will now be described with reference to the accompanying drawings, which form a part hereof. It is to be understood that other embodiments may be utilized, structural, functional and procedural modifications, additions or omissions may be made, and features of the exemplary embodiments, whether apparatus or methods, may be combined without departing from the scope and spirit of the invention.

[0072] The apparatus and methods may include illustrative Example 1 and Comparative Examples 1 and 2, which further illustrate the apparatus and methods and devices for staged absorption ammonia-based decarbonation of the present invention.

[0073] An example is shown in Figure 1.

[0074] Example 1 The process gas 1 after ammonia-based desulfurization enters the ammonium bicarbonate production zone 2, and the solution is cooled via the ammonium bicarbonate production zone circulation pump 3 and the ammonium bicarbonate production zone heat exchanger 4, and reacts with the flue gas to form ammonium bicarbonate. The ammonium bicarbonate solution / slurry is sent to the crystallizer 27 via the ammonium bicarbonate discharge pump 26, and then passes through the solid-liquid separation equipment 28 and the filling machine 29 to obtain solid ammonium bicarbonate 30.

[0075] The gas further enters the decarbonation absorption zone 6, which includes a first stage decarbonation absorption zone 7, a second stage decarbonation absorption zone 9 and a third stage decarbonation absorption zone 11 from the bottom to the top, and these zones are separated by a liquid collector. The liquid collector adopts a tray and gas cap structure, which allows the gas to pass from the bottom to the top, and collects the circulating liquid in the upper region. In the first stage decarbonation absorption zone 7, the circulating liquid is cooled through the first stage decarbonation absorption zone circulating pump 12 and the first stage decarbonation absorption zone heat exchanger 13, and contacts with the flue gas to absorb carbon dioxide, and a part of the circulating liquid is directed to the ammonium bicarbonate generation zone 2. The gas enters the second stage decarbonation absorption zone 9 through a liquid collector 8, the circulating liquid is cooled through a second stage decarbonation absorption zone circulation pump 14 and a second stage decarbonation absorption zone heat exchanger 15, contacts with the flue gas to absorb carbon dioxide, and a part of the circulating liquid is directed to the first stage decarbonation absorption zone 7. Ammonia 5 is supplied to the first stage decarbonation absorption zone 7 and the second stage decarbonation absorption zone 9 through a pipe. The gas enters the third stage decarbonation absorption zone 11 through a liquid collector 10, the circulating liquid is cooled through a third stage decarbonation absorption zone circulation pump 16 and a third stage decarbonation absorption zone heat exchanger 17, contacts with the flue gas to absorb carbon dioxide, and a part of the circulating liquid is directed to the second stage decarbonation absorption zone 9.

[0076] The gas continues to enter the ammonia leakage control system 18. The ammonia leakage control system includes an ammonia leakage control system water washing zone 19 and an ammonia leakage control system acid washing zone 21 from bottom to top. The two zones are separated by a liquid collector. The liquid collector adopts a tray and gas cap structure, which allows the gas to pass from bottom to top and collects the circulating liquid in the upper region. In the ammonia leakage control system water washing zone 19, the circulating liquid is washed via a circulating pump 22 in the ammonia leakage control system water washing zone, and contacts the flue gas to absorb the free ammonia. The gas enters the ammonia leakage control system acid washing zone 21 through a liquid collector 20, and the circulating liquid 24 from the ammonia system desulfurization system is used to contact the flue gas to absorb the free ammonia, and the reacted solution (i.e., the desulfurization circulating liquid) 23 returns to the desulfurization system. The flue gas after ammonia removal is discharged 25.

[0077] The temperature control is performed by lowering the temperature of the circulating liquid through a cold heat source, and the circulating liquid contacts the flue gas to lower the temperature of the flue gas. For the cold heat source, a refrigerator is used to generate cold water, which cools the circulating liquid through a plate heat exchanger. The circulating liquid contacts the flue gas by spraying to lower the temperature of the flue gas. The temperature of the ammonium hydrogen carbonate generation circulating liquid is controlled to 20°C to 25°C, preferably 22°C. In the first stage, the temperature of the decarbonation and absorption circulating liquid is higher than the temperature of the ammonium hydrogen carbonate generation circulating liquid, and in the final stage, the temperature of the decarbonation and absorption circulating liquid is lower than the temperature of the ammonium hydrogen carbonate generation circulating liquid.

[0078] pH control is by addition of ammonia and solution replacement between stages.

[0079] Ammonia is added to the first-stage decarbonation absorption circulating liquid and the second-stage decarbonation absorption circulating liquid, and the amount of ammonia added to the second-stage decarbonation absorption circulating liquid is 80 to 50% by weight, preferably 60% by weight, of the total amount of ammonia added. No ammonia is added to the third-stage decarbonation absorption circulating liquid and the ammonium hydrogen carbonate production circulating liquid.

[0080] The solution replacement is carried out through an overflow pipe for transporting the circulating liquid of the previous stage to the next stage, which can control the solution composition and pH value. The pH value of the ammonium bicarbonate production circulating liquid is lower than that of the decarbonation absorption circulating liquid, and the ammonium bicarbonate content of the ammonium bicarbonate production circulating liquid is higher than that of the decarbonation absorption circulating liquid.

[0081] In the decarbonation absorption circulating liquid, the pH value is 8.0 or more, preferably 8.2 or more, more preferably 8.5 or more, and most preferably 9.0 or more.

[0082] The system operates under normal pressure (actual pressure is slightly above atmospheric pressure, specific pressures are given in the table below) and is not equipped with a pressure control device.

[0083] Among these, the solution compositions and control conditions are shown in the table below.

[0084] [Table 1]

[0085] Ammonia decarbonation adopts 99.6% anhydrous ammonia as the absorbent, and the parameters of process gas 1 are shown in Table 1 below.

[0086] [Table 2]

[0087] The main parameters of the process gas after being treated in the decarbonation absorption zone 6 are shown in Table 2 below.

[0088] [Table 3]

[0089] The main parameters of the process gas after being treated by the ammonia scrubber 18 are given in the table below.

[0090] [Table 4]

[0091] Comparative Example 1 Only the temperature control was different from Example 1. The temperature control of the first-stage decarbonation / absorption zone and the second-stage decarbonation / absorption zone was the same as that of the third stage, and both were set to 20°C.

[0092] The temperature control of the first-stage decarbonation absorption zone and the second-stage decarbonation absorption zone is relatively low, and the temperature difference with respect to the cold heat source is reduced, so the required heat exchange area of ​​the heat exchanger 13 and the heat exchanger 14 increases, and the capital investment cost increases. In addition, when the ambient temperature is 20°C, the cold heat source of the first-stage decarbonation absorption zone heat exchanger 13 and the second-stage decarbonation absorption zone heat exchanger 15 in Example 1 adopts cooling by an air cooler using low-temperature ambient air, so that the operating cost can be saved. In Comparative Example 1, the ambient temperature is the same as the target temperature and both are set to 20°C, so cooling by an air cooler is not possible, and only cold water, which consumes high energy, can be used for cooling.

[0093] Comparative Example 2 Comparative Example 2 differs from Example 1 only in the amount of ammonia added. Equal amounts of ammonia were added to the ammonium hydrogen carbonate production zone, the first-stage decarbonation / absorption zone, the second-stage decarbonation / absorption zone, and the third-stage decarbonation / absorption zone.

[0094] The amount of ammonia added in the ammonium hydrogen carbonate production zone reaches 25% by weight, so that ammonium hydrogen carbonate cannot be produced in the solution and ammonium hydrogen carbonate crystals cannot be obtained. The amount of ammonia added in the third stage decarbonation absorption zone reaches 25% by weight, which leads to a significant increase in decarbonation ammonia leakage, and the ammonia leakage of the process gas after treatment in the decarbonation absorption zone 6 reaches 6000 ppm.

[0095] As can be seen from the comparison between the above-mentioned examples of the present invention and the comparative examples, efficient decarbonation can be achieved while controlling ammonia leakage through stepwise solution composition control and reaction condition control by the treatment using the method and apparatus of the present invention, thereby achieving excellent technical and economic effects.

[0096] Other Exemplary Embodiments 1. A process for staged absorption ammonia-based decarbonation, using an absorption circulating liquid containing ammonium salts to remove carbon dioxide in the gas, and controlling ammonia breakthrough while achieving efficient decarbonation through staged solution composition control and reaction condition control. 2. Stepwise solution composition control reduces total CO 2 2. The method of claim 1, wherein the solution composition is characterized by a molar ratio of total ammonia to ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonia, or a combination thereof. 3. The method of embodiment 1, wherein the reaction condition control includes temperature control, pH control, and pressure control. 4. The cooled flue gas is sequentially contacted with the ammonium bicarbonate production circulating liquid and the decarbonation absorption circulating liquid to realize the synergistic control of ammonium bicarbonate production, ammonium bicarbonate crystallization, carbon dioxide absorption and ammonia leakage, and the ammonium bicarbonate production liquid is provided with at least one stage of gas-liquid contact to remove all CO in the solution. 2 The molar ratio of total ammonia to total CO is 1 to 3, preferably 1 to 2, and the total ammonia includes ammonia and ammonium radicals. 2 is free CO 2 and carbonized CO 2 and The decarbonation absorption liquid is provided with at least two stages of gas-liquid contact, and the total CO in the solution in the first stage is 2 The molar ratio of total ammonia to total CO in the solution between the first and final stages is 1.2 to 4, preferably 1.4 to 3.5, more preferably 1.6 to 3, and most preferably 1.8 to 2.5. 2The molar ratio of total ammonia to total CO in the solution in the final stage is 1.5 to 4.5, preferably 1.8 to 4, more preferably 2 to 3.5. 2 The method according to embodiment 2, wherein the molar ratio of total ammonia to is 1-3, preferably 1.2-2.8, more preferably 1.5-2.5, and most preferably 1.6-2. 5. The method according to embodiment 4, wherein the gas-liquid contact form of the ammonium hydrogen carbonate production liquid is preferably spray type, filling type and bubbling type, and the gas-liquid contact form of the decarbonation absorption liquid is preferably spray type and filling type. 5. The method of embodiment 4, wherein the pH value of the ammonium bicarbonate production liquid is lower than the pH value of the decarbonated absorption liquid, and the ammonium bicarbonate content thereof is higher than the ammonium bicarbonate content of the decarbonated absorption liquid. 6. The method according to embodiment 4, wherein the pH value of the decarboxylated absorption liquid is greater than 8.0, preferably greater than or equal to 8.2, more preferably greater than or equal to 8.5, and most preferably greater than or equal to 9.0. 7. The method according to embodiment 4, wherein ammonia is mainly added to the decarbonation absorption liquid, no or little ammonia is added to the ammonium bicarbonate production liquid, and the amount of ammonia added to the decarbonation absorption liquid in the final stage is less than that in the previous stage, or no ammonia is added. 8. The method of embodiment 7, wherein ammonia is added to the decarbonated absorption liquid separately in multiple stages. 9. The method according to embodiment 3, wherein the temperature of the ammonium bicarbonate production liquid is 10-30°C, preferably 12-28°C, preferably 15-25°C, most preferably 16-22°C, and in the first stage, the temperature of the decarbonation absorption liquid is higher than that of the ammonium bicarbonate production liquid, and in the final stage, the temperature of the decarbonation absorption liquid is lower than that of the ammonium bicarbonate production liquid. 10. The method of embodiment 4, wherein the ammonia-based decarbonation device maintains a pressure of ±50 kPa, preferably ±40 kPa, more preferably ±30 kPa, and most preferably ±25 kPa. 11.Clean flue gas SO 2 However, 10mg / Nm 3Less than 5mg / Nm 3 Less than 2mg / Nm, more preferably 3 2. The method of embodiment 1, wherein the 12. The method of embodiment 1, wherein the ammonia breakthrough of the clean flue gas is not more than 20 ppm, preferably not more than 15 ppm, more preferably not more than 10 ppm. 13.CO 2 2. The method of embodiment 1, wherein the removal efficiency is 60% or more, preferably 80% or more. 14. An apparatus for staged absorption ammonia system decarbonation including a decarbonation system, an ammonia leakage control system, an ammonium bicarbonate treatment system, an ammonia supply system, and a cooling system. 15. The apparatus of embodiment 14, wherein the decarbonation system employs zone control including an ammonium bicarbonate production zone and a decarbonation absorption zone, the ammonium bicarbonate production zone is provided with at least one stage of gas-liquid contacting, the decarbonation absorption zone is provided with at least two stages of gas-liquid contacting, and between the zones and stages, there is provided equipment / components that allow only gas to pass. 16. The apparatus of embodiment 14, wherein one or more demister layers are provided after the final stage of the decarbonation absorption zone, and optionally the remaining layers are not provided with one or more demister layers, and the demister is of the baffle, ridge, packing and screen type, or a combination thereof. 17. An apparatus as described in embodiment 14, wherein the ammonia leakage control system employs a multi-stage cleaning cycle control and is provided with at least one layer of acidic solution cleaning. 18. The apparatus of embodiment 14, wherein a cooling system is used to reduce the temperature of the ammonium bicarbonate production liquid and the decarbonation absorption liquid. 19. The apparatus of embodiment 14, wherein the ammonium bicarbonate processing system comprises an ammonium bicarbonate crystallization facility and a solid-liquid separation facility. 20. The method of embodiment 3, wherein the flue gas is contacted sequentially with ammonium bicarbonate generating liquid and decarbonation absorbing liquid to achieve synergistic control of ammonium bicarbonate production, ammonium bicarbonate crystallization, carbon dioxide absorption and ammonia release, wherein temperature control is achieved by lowering the temperature of the ammonium bicarbonate generating liquid and the decarbonation absorbing liquid via a cold source, the ammonium bicarbonate generating liquid and the decarbonation absorbing liquid are contacted with the flue gas to lower the flue gas temperature, pH control is achieved via ammonia addition or solution displacement between stages, and pressure control is achieved by providing control valves or liquid seals in the ammonia-based decarbonation system and similar means, and no pressure control device is provided for atmospheric operation. 21.CO in process gas before decarbonation 2 The content is 6 to 50v%, preferably 8 to 40v%, more preferably 10 to 30v%, and the CO 2 The method according to embodiment 1, wherein the content is 0 to 10v%, preferably 0 to 8v%, preferably 0 to 6v%. 22. The method of embodiment 1, wherein the gas is ammonia-based desulfurized process gas.

[0097] All ranges and parameters disclosed herein are to be understood to encompass any and all subranges subsumed therein, all numbers between the endpoints, and the endpoints. For example, a range stated as "1 to 10" should be considered to include any and all subranges between (and including) the minimum value of 1 and the maximum value of 10, i.e., beginning with a minimum value of 1 or more (e.g., 1 to 6.1) and ending with a maximum value of 10 or less (e.g., 2.3 to 9.4, 3 to 8, 4 to 7), and ending with each of the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 included within the range.

[0098] Thus, an apparatus and method for staged absorption ammonia-based decarbonation has been provided. Those skilled in the art will appreciate that the invention may be practiced other than by the described embodiments, which are presented for purposes of illustration and not limitation. The invention is limited only by the scope of the following claims. [Explanation of symbols]

[0099] Process Gas 1 Ammonium hydrogen carbonate generation zone 2 Ammonium bicarbonate production zone circulation pump 3 Ammonium bicarbonate generation zone heat exchanger 4 Ammonia 5 Decarbonation absorption zone 6 First stage decarbonation absorption zone 7 Liquid collector 8 Second stage decarbonation absorption zone 9 Liquid collector 10 Third stage decarbonation absorption zone 11 1st stage decarbonation absorption zone circulation pump 12 1st stage decarbonation absorption zone heat exchanger 13 Second stage decarbonation absorption zone circulation pump 14 Second stage decarbonation absorption zone heat exchanger 15 3rd stage decarbonation absorption zone circulation pump 16 3rd stage decarbonation absorption zone heat exchanger 17 Ammonia Leak Control System 18 Ammonia leak control system water washing zone 19 Liquid collector 20 Ammonia Leak Control System Acid Cleaning Zone 21 Ammonia leak control system water washing zone circulation pump 22 Desulfurization circulating liquid return 23 Circulating liquid from ammonia-based desulfurization system 24 Flue Gas Emissions 25 Ammonium bicarbonate discharge pump 26 Crystallizer 27 Solid-liquid separation equipment 28 filling machine 29 Solid Ammonium Bicarbonate 30

Claims

1. A process for staged absorption ammonia-based decarbonation using an absorption circulating liquid containing ammonium salts to remove carbon dioxide in a gas, and controlling ammonia breakthrough while achieving efficient decarbonation through staged solution composition control and reaction condition control.

2. The stepwise solution composition control is ２ 2. The method of claim 1, wherein the solution composition is characterized by a molar ratio of total ammonia to ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonia, or a combination thereof.

3. The method of claim 1 , wherein the reaction condition control includes temperature control, pH control, and pressure control.

4. The cooled flue gas is sequentially contacted with an ammonium bicarbonate production circulating liquid and a decarbonation absorption circulating liquid to achieve synergistic control of ammonium bicarbonate production, ammonium bicarbonate crystallization, carbon dioxide absorption and ammonia leakage; The ammonium bicarbonate-producing liquid is subjected to at least one stage of gas-liquid contact, and the total CO ２ The molar ratio of total ammonia to total CO is 1 to 3, preferably 1 to 2, where total ammonia includes ammonia and ammonium radicals, and total CO ２ is free CO ２ and carbonized CO ２ Including, The decarbonated absorption liquid is subjected to at least two stages of gas-liquid contact, and the total CO ２ The molar ratio of total ammonia to total CO in solution between the first and last stages is 1.2 to 4, preferably 1.4 to 3.5, more preferably 1.6 to 3, and most preferably 1.8 to 2.

5. ２ The molar ratio of total ammonia to total CO in the solution in the final stage is 1.5 to 4.5, preferably 1.8 to 4, more preferably 2 to 3.

5. ２ The process according to claim 2, wherein the molar ratio of total ammonia to is from 1 to 3, preferably from 1.2 to 2.8, more preferably from 1.5 to 2.5, and most preferably from 1.6 to 2.

5. The gas-liquid contact form of the ammonium hydrogen carbonate production liquid is preferably a spray type, a filling type, or a bubbling type, and the gas-liquid contact form of the decarbonation absorption liquid is preferably a spray type or a filling type.

6. 5. The method of claim 4, wherein the pH value of the decarbonated absorption liquid is greater than 8.0, preferably greater than or equal to 8.2, more preferably greater than or equal to 8.5, and most preferably greater than or equal to 9.

0.

7. The method according to claim 4, wherein ammonia is mainly added to the decarbonated absorption liquid, no or almost no ammonia is added to the ammonium bicarbonate generating liquid, and the amount of ammonia added to the final stage decarbonated absorption liquid is less than the amount of ammonia added to the previous stage decarbonated absorption liquid, or no ammonia is added.

8. 8. The method of claim 7, wherein ammonia is added to the decarbonated absorption liquid separately in multiple stages.

9. 4. The method according to claim 3, wherein the temperature of the ammonium bicarbonate producing liquid is 10-30°C, preferably 12-28°C, preferably 15-25°C, most preferably 16-22°C, and wherein in a first stage the temperature of the decarbonation absorbing liquid is higher than that of the ammonium bicarbonate producing liquid, and in a final stage the temperature of the decarbonation absorbing liquid is lower than that of the ammonium bicarbonate producing liquid.

10. 5. The method of claim 4, wherein the ammonia based decarbonation unit maintains atmospheric pressure ±50 kPa, preferably atmospheric pressure ±40 kPa, more preferably atmospheric pressure ±30 kPa, and most preferably atmospheric pressure ±25 kPa.

11. SO of clean flue gas ２ However, 10 mg / Nm ３ Less than 5 mg / Nm ３ Less than 2 mg / Nm, more preferably ３ The method of claim 1 , wherein the

12. 2. The method of claim 1, wherein the ammonia breakthrough of the clean flue gas is less than or equal to 20 ppm, preferably less than or equal to 15 ppm, more preferably less than or equal to 10 ppm.

13. CO ２ 2. The method according to claim 1, wherein the removal efficiency is at least 60%, preferably at least 80%.

14. An apparatus for staged absorption ammonia-based decarbonation, including a decarbonation system, an ammonia breakthrough control system, an ammonium bicarbonate treatment system, an ammonia supply system, and a cooling system.

15. 15. The apparatus according to claim 14, wherein the decarbonation system employs zone control including an ammonium bicarbonate production zone and a decarbonation absorption zone, the ammonium bicarbonate production zone is provided with at least one stage of gas-liquid contacting, the decarbonation absorption zone is provided with at least two stages of gas-liquid contacting, and between the zones and the stages, equipment / components are provided that allow only gas to pass.

16. 15. The apparatus of claim 14, wherein one or more layers of demisters are provided after the final stage of the decarbonation absorption zone, and optionally the remaining layers are not provided with one or more layers of demisters, and the demisters are of the baffle, ridge, packing and screen type, or combinations thereof.

17. 15. The apparatus of claim 14, wherein the ammonia leakage control system employs a multi-stage cleaning cycle control and is provided with at least one layer of acid solution cleaning.

18. 15. The apparatus of claim 14, wherein the cooling system is used to reduce the temperature of the ammonium bicarbonate product liquid and the decarbonated absorption liquid.

19. 15. The apparatus of claim 14, wherein the ammonium bicarbonate processing system comprises an ammonium bicarbonate crystallization facility and a solid-liquid separation facility.

20. contacting the flue gas with the ammonium bicarbonate-producing liquid and the decarbonation absorption liquid in sequence to achieve synergistic control of ammonium bicarbonate production, ammonium bicarbonate crystallization, carbon dioxide absorption and ammonia leakage; The temperature control includes lowering the temperature of the ammonium bicarbonate generating liquid and the decarbonation absorbing liquid via a cold source, and the ammonium bicarbonate generating liquid and the decarbonation absorbing liquid are brought into contact with the flue gas to lower the temperature of the flue gas; The pH control is achieved via addition of ammonia or solution replacement between the stages; 4. The method of claim 3, wherein the pressure control is achieved by providing control valves or liquid seals in the ammonia-based decarbonation system and similar means, and no pressure control devices are provided for atmospheric operation.

21. CO in process gas before decarbonation ２ The content is 6 to 50v%, preferably 8 to 40v%, more preferably 10 to 30v%, and the CO ２ The method according to claim 1, wherein the content is 0-10v%, preferably 0-8v%, preferably 0-6v%.

22. The method of claim 1 , wherein the gas is an ammonia-based desulfurized process gas.

23. 5. The method of claim 4, wherein the pH value of the ammonium bicarbonate product liquid is lower than the pH value of the decarbonated absorption liquid and the ammonium bicarbonate content thereof is greater than the ammonium bicarbonate content of the decarbonated absorption liquid.

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