A wet desulfurization process for flue gas purification

Abstract

The invention relates to the technical field of air pollution control, and in particular to a wet desulfurization process for flue gas purification, which comprises the following steps: treating flue gas, removing solidified matter in the flue gas, and introducing an absorption reaction liquid into an absorption tower for reaction, wherein the sulfide reacts with a pre-reaction agent to generate a negatively charged complex and reacts and fixes the positively charged skeleton in the ion absorption reaction liquid, and the sulfur-rich absorption reaction liquid obtained after the reaction is completed enters a heat exchanger and a preheater and then enters a regeneration tower to promote the precipitation of sulfur dioxide, and the absorption reaction liquid obtained at last is recovered and enters an absorption tower for recycling. The process of the invention is simple, can realize the recycling of a desulfurizer, has a high desulfurization rate, and can obtain high-purity sulfur dioxide gas.

Description

Technical Field

[0001] The invention relates to the technical field of air pollution control, and in particular to a wet desulfurization process for flue gas purification. Background Art

[0002] Air pollution is man-made or naturally generated pollution that circulates in the atmosphere, causing pollutant concentrations to be too high, which can cause acid rain and other phenomena that damage the ecosystem, and easily trigger a series of natural hazards. It can also cause serious damage to human health and lead to symptoms such as the respiratory system; and industrial flue gas pollution is an important cause of pollution. Therefore, limiting the use of fossil fuels and strictly controlling industrial flue gas are important measures to reduce pollution.

[0003] Existing flue gas desulfurization processes include dry desulfurization process and wet desulfurization process, but the desulfurization rate of dry and semi-dry desulfurization processes is low, and difficult equipment maintenance is required. In comparison, the wet desulfurization process has the advantages of high desulfurization rate and fast reaction, so it still occupies a dominant position. The main method is the gypsum method: first absorb SO2 to generate CaSO3, and then oxidize CaSO3 in the absorption tower to CaSO4 by blowing air. It has the characteristics of high desulfurization rate, but the obtained gypsum and wastewater are difficult to handle, and it is easy to cause corrosion and wear to the equipment; magnesium chloride-magnesium sulfate heptahydrate recovery method: generate polyhydrated magnesium sulfite; double alkali method: SO2 is adsorbed by a soluble absorption reaction liquid containing two different types of alkali, and the obtained absorption reaction liquid is regenerated with lime milk; and other desulfurization methods; the above wet desulfurization process has a large desulfurizer loss, and the by-products need to be treated, and the solids formed are easy to cause blockage; therefore, on the basis of the existing process, a wet desulfurization process with rapid adsorption and product separation and regeneration, taking into account both efficient desulfurization and low solid waste generation has good economic and technical significance. Summary of the invention

[0004] In view of the above problems, the object of the present invention is to provide a wet desulfurization process for flue gas purification.

[0005] The technical contents of the present invention are as follows: The present invention provides a wet desulfurization process for flue gas purification, comprising the following steps: Step 1: Treat the flue gas and pass it into the absorption reaction liquid in the absorption tower for reaction. After the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into the heat exchanger for heating; The treatment comprises treating the flue gas in an electrostatic field with a strength of 0.1-0.6 V / m for 4-8 minutes; after the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in the upper layer and a post-reaction agent in the lower layer in a volume ratio of 1:1-3; The reaction is carried out at a pressure of 0.1-0.4 MPa for 20-30 min; The pre-reaction agent is composed of a catalyst, ammonium polyphosphate and a carboxylate in a mass ratio of 3-5:15-19:1-3, and is dispersed in water in a solid-liquid ratio of 7-10:20-25 g / ml; The catalyst includes sodium hydroxymethane sulfonate; The pre-reaction agent is an aqueous reactant, wherein the negatively charged phosphate group and the anionic carboxylate group can undergo oxidation and complexation reaction with the sulfide in the flue gas under the action of a catalyst to form a charged ion complex with electrochemical activity, wherein the sulfonate group and the active adsorption sites in the carboxylate can promote the dispersion of the sulfide in the solution for reaction; The post-reaction agent includes: by weight: 13-18 parts of ionic liquid, 1-3 parts of inorganic salt, 3-5 parts of polyamine compound, 4-7 parts of histidine; the inorganic salt is one of sodium chloride, calcium chloride and magnesium chloride; The ionic liquid is an imidazole-type ionic liquid treated with rich charge, and the method for rich charge treatment is to add the imidazole-type ionic liquid into a buffer solution and stir and mix, wherein the buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide at a mass ratio of 3-5:2, and then dispersed in water at a solid-liquid ratio of 1:10-14 g / mL; The preparation method of the post-reaction agent is as follows: all the raw materials are mixed by weight, ultrasonicated, stirred at an ultrasonic frequency of 10-20 KHz for 10-20 minutes, then heated to 60-70° C. in a reactor, refluxed for 8-10 hours, and then cooled to room temperature; In the charge-rich treatment of the ionic liquid in the post-reaction agent, the positive charge sites are increased by modification with positive zinc ions and quaternary ammonium groups, and the ionic liquid and the anion undergo cross-linking polymerization reaction in a molten salt system. The cavitation effect of ultrasound and the positive charge skeleton with reaction vacancies and electrostatic adsorption formed by the reflux polymerization reaction form an absorption reaction liquid with a higher density, which is attractively combined with the negatively charged sulfide through the charged groups. The imidazole group in the histidine of the post-reaction agent is introduced therein, and its dispersion effect prompts it to further form a certain space that is more conducive to the reaction, and is accompanied by multiple reactions such as molecular chain entanglement and hydrogen bonding, so that the desulfurization effect is strong; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a temperature of 60-80°C; Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment to obtain purified flue gas, and the absorption reaction liquid in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling; The specific process of the regeneration treatment is to pass the sulfur-rich absorption reaction liquid into air for heating reaction; the heating reaction is to react at a temperature of 100-120°C for 50-70 minutes, and the SO2 gas is further precipitated by heating and passing air. The ion absorption reaction liquid is heated under the action of water and air to promote the decomposition of the polymer therein, so that the sulfide is more easily precipitated, thereby improving the regeneration efficiency of the sulfide.

[0006] Beneficial effects of the present invention: Compared with the general wet desulfurization process, the wet desulfurization process provided by the present invention processes the flue gas, removes the solid waste and then introduces the absorption reaction liquid in the absorption tower for pressurization reaction, wherein the sulfide reacts with the pre-reaction agent to generate a negatively charged complex and reacts and fixes the positively charged skeleton in the ion absorption reaction liquid, after the reaction is completed, the sulfur-rich absorption reaction liquid is preheated and enters the regeneration tower to promote the precipitation of sulfur dioxide under the condition of air, and finally the absorption reaction liquid is passed through a heat exchanger and a preheater and then enters the absorption tower for recycling; the process realizes the recycling of the desulfurizer, has a high desulfurization rate, and obtains high-purity sulfur dioxide gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0008] The present invention is further described in detail below through specific implementation cases. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art are all within the scope of the claims attached to this application.

[0009] Unless otherwise specified, all raw materials and reagents of the present invention are raw materials and reagents from the conventional market.

[0010] Example 1 A wet desulfurization process for flue gas purification comprises the following steps, wherein the specific process flow chart is as follows: Figure 1 As shown; Step 1: Take the SO2 concentration of coal-fired power plant emissions as 173.51 g / Nm 3 The soot is treated at an electrostatic field strength of 0.3 V / m for 6 minutes, and the absorption reaction liquid introduced into the absorption tower is reacted at a pressure of 0.2 MPa for 50 minutes; after the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in the upper layer and a post-reaction agent in the lower layer in a volume ratio of 1:2; The pre-reaction agent is composed of sodium hydroxymethyl sulfonate, ammonium polyphosphate and alcohol ether carboxylate in a mass ratio of 4:17:2, and is dispersed in water in a solid-liquid ratio of 8:22 g / ml; The preparation method of the post-reaction agent is as follows: 16 parts of ionic liquid, 2 parts of calcium chloride, 4 parts of triethylamine, and 5 parts of histidine are mixed and then ultrasonicated, stirred at an ultrasonic frequency of 15KHz for 15 minutes, then heated to 65°C in a reactor, refluxed for 9 hours, and then cooled to room temperature; The ionic liquid is a charge-rich treated 1-ethyl-3-methylimidazolium bromide ionic liquid, and the charge-rich treatment method is to add the imidazole type ionic liquid into a buffer solution and stir and mix, wherein the buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide at a mass ratio of 4:2, and then dispersed in water at a solid-liquid ratio of 1:12 g / mL; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a preheating temperature of 70° C. Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment, specifically, the sulfur-rich absorption reaction liquid is introduced into the air for heating reaction, and the reaction is carried out at a temperature of 110° C. for 60 minutes to obtain purified flue gas, and the absorption reaction liquid containing the aqueous pre-reaction agent and the post-polymerization reaction agent in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling, and the sulfur-rich absorption liquid in the absorption tower is heated by heat energy exchange in the heat exchanger; The SO2 concentration of the gas detected at the outlet of the regeneration tower was 2.64 g / Nm 3 The desulfurization rate is 98.5%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 97.1%.

[0011] Example 2 A wet desulfurization process for flue gas purification comprises the following steps: Step 1: Take the SO2 concentration of coal-fired power plant emissions as 170.87 g / Nm 3 The soot is treated at an electrostatic field strength of 0.1 V / m for 8 minutes, and the absorption reaction liquid introduced into the absorption tower is reacted at a pressure of 0.1 MPa for 40 minutes; after the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in an upper layer and a post-reaction agent in a lower layer in a volume ratio of 1:1; The pre-reaction agent is composed of sodium hydroxymethyl sulfonate, ammonium polyphosphate and alcohol ether carboxylate in a mass ratio of 3:15:1, and is dispersed in water in a solid-liquid ratio of 7:20 g / ml; The preparation method of the post-reaction agent is as follows: 13 parts of ionic liquid, 1 part of sodium chloride, 3 parts of ethylenediamine, and 4 parts of histidine are mixed and then ultrasonicated, stirred at an ultrasonic frequency of 10 KHz for 10 minutes, then heated to 60° C. in a reactor, refluxed for 8 hours, and then cooled to room temperature; The ionic liquid is a charge-rich treated 1-ethyl-3-ethylamino imidazole bis(trifluoromethanesulfonyl)imide salt ionic solution, and the charge-rich treatment method is to add the imidazole type ionic liquid into a buffer solution and stir and mix, wherein the buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide at a mass ratio of 3:2, and then dispersed in water at a solid-liquid ratio of 1:10 g / mL; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a preheating temperature of 60° C. Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment, specifically, the sulfur-rich absorption reaction liquid is introduced into the air for heating reaction, and the reaction is carried out at a temperature of 100° C. for 50 minutes to obtain purified flue gas, and the absorption reaction liquid in the regeneration tower passes through a heat exchanger and enters the absorption tower for recycling; The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 3.01 g / Nm 3 The desulfurization rate is 98.2%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 96%.

[0012] Example 3 A wet desulfurization process for flue gas purification comprises the following steps: Step 1: Take the SO2 concentration of coal-fired power plant emissions as 167.05 g / Nm 3 The soot is treated at an electrostatic field strength of 0.6 V / m for 8 minutes, and the absorption reaction liquid introduced into the absorption tower is reacted at a pressure of 0.4 MPa for 60 minutes; after the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in the upper layer and a post-reaction agent in the lower layer in a volume ratio of 1:3; The pre-reaction agent is composed of sodium hydroxymethyl sulfonate, ammonium polyphosphate and alcohol ether carboxylate in a mass ratio of 5:19:3, and is dispersed in water in a solid-liquid ratio of 10:25 g / ml; The preparation method of the post-reaction agent is as follows: 18 parts of ionic liquid, 3 parts of sodium chloride, 5 parts of ethylenediamine, and 7 parts of histidine are mixed and then ultrasonicated, stirred at an ultrasonic frequency of 20 KHz for 20 minutes, then heated to 70° C. in a reactor, refluxed for 10 hours, and then cooled to room temperature; The ionic liquid is a 1-ethyl-3-methylimidazolium bromide ionic liquid treated with rich charge, and the charge-rich treatment method is to add the imidazole ionic liquid into a buffer solution and stir and mix, wherein the buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide at a mass ratio of 5:2, and then dispersed in water at a solid-liquid ratio of 1:14 g / mL; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a preheating temperature of 80° C. Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment, specifically, the sulfur-rich absorption reaction liquid is introduced into the air for heating reaction, and the reaction is carried out at a temperature of 120° C. for 70 minutes; the purified flue gas is obtained, and the absorption reaction liquid in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling; The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 3.18 g / Nm 3 The desulfurization rate is 98.1%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 96.9%.

[0013] Example 4 A wet desulfurization process for flue gas purification comprises the following steps: Step 1: The flue gas is treated at an electrostatic field strength of 0.6 V / m for 4 minutes, and the absorption reaction liquid introduced into the absorption tower is reacted at a pressure of 0.4 MPa for 40 minutes; the sulfur-rich absorption reaction liquid obtained after the reaction is completed is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in an upper layer and a post-reaction agent in a lower layer in a volume ratio of 1:1; The pre-reaction agent is composed of sodium hydroxymethyl sulfonate, ammonium polyphosphate and alcohol ether carboxylate in a mass ratio of 5:15:3, and is dispersed in water in a solid-liquid ratio of 7:25 g / ml; The preparation method of the post-reaction agent is as follows: 13 parts of ionic liquid, 3 parts of magnesium chloride, 3 parts of diethylenetriamine, and 7 parts of histidine are mixed and then ultrasonicated, stirred at an ultrasonic frequency of 10KHz for 20 minutes, then heated to 60°C in a reactor, refluxed for 10 hours, and then cooled to room temperature; The ionic liquid is a 1-allyl-3-vinylimidazolium chloride ionic liquid treated with rich charge. The method for rich charge treatment is to add the imidazole ionic liquid into a buffer solution and stir and mix. The buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide at a mass ratio of 3:2, and then dispersed in water at a solid-liquid ratio of 1:14 g / mL; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a preheating temperature of 65° C. Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment, specifically, the sulfur-rich absorption reaction liquid is introduced into the air for heating reaction, and the reaction is carried out at a temperature of 105°C for 50 minutes to obtain purified flue gas, and the absorption reaction liquid in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling; The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 3.46 g / Nm 3 The desulfurization rate is 97.9%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 96.2%.

[0014] Example 5 A wet desulfurization process for flue gas purification comprises the following steps: Step 1: Take the SO2 concentration of coal-fired power plant emissions as 171.51 g / Nm 3 The soot is treated at an electrostatic field strength of 0.1 V / m for 8 minutes, and the absorption reaction liquid introduced into the absorption tower is reacted at a pressure of 0.1 MPa for 60 minutes; after the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in an upper layer and a post-reaction agent in a lower layer in a volume ratio of 1:1; The pre-reaction agent is composed of sodium hydroxymethyl sulfonate, ammonium polyphosphate and alcohol ether carboxylate in a mass ratio of 3:19:1, and is dispersed in water in a solid-liquid ratio of 10:20 g / ml; The preparation method of the post-reaction agent is as follows: 18 parts of ionic liquid, 1 part of sodium chloride, 5 parts of triethylenetetramine and 4 parts of histidine are mixed and then ultrasonicated, stirred at an ultrasonic frequency of 15KHz for 10 minutes, then heated to 70°C in a reactor, refluxed for 8 hours, and then cooled to room temperature; The ionic liquid is 1-allyl-3-methylimidazolium hexafluorophosphate treated with rich charge, and the charge-rich treatment method is to add the imidazole type ionic liquid into a buffer solution and stir and mix, wherein the buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide at a mass ratio of 3:2, and then dispersed in water at a solid-liquid ratio of 1:12 g / mL; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a preheating temperature of 75° C. Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment, specifically, the sulfur-rich absorption reaction liquid is introduced into the air for heating reaction, and the reaction is carried out at a temperature of 115° C. for 70 minutes; the purified flue gas is obtained, and the absorption reaction liquid in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling; The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 2.71 g / Nm 3The desulfurization rate is 98.4%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 96.9%.

[0015] Example 6 A wet desulfurization process for flue gas purification comprises the following steps: Step 1: Take the SO2 concentration of coal-fired power plant emissions as 170.78 g / Nm 3 The soot is treated at an electrostatic field strength of 0.5 V / m for 7 minutes, and the absorption reaction liquid introduced into the absorption tower is reacted at a pressure of 0.3 MPa for 55 minutes; after the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into a heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in the upper layer and a post-reaction agent in the lower layer in a volume ratio of 1:3; The pre-reaction agent is composed of sodium hydroxymethyl sulfonate, ammonium polyphosphate and alcohol ether carboxylate in a mass ratio of 4:18:2, and is dispersed in water in a solid-liquid ratio of 9:24 g / ml; The preparation method of the post-reaction agent is as follows: 17 parts of ionic liquid, 2 parts of sodium chloride, 4 parts of diethylenetriamine, and 6 parts of histidine are mixed and then ultrasonicated, stirred at an ultrasonic frequency of 15KHz for 10 minutes, then heated to 65°C in a reactor, refluxed for 9 hours, and then cooled to room temperature; The ionic liquid is 1-octyl-3-butyl imidazole hexafluorophosphate treated with rich charge, and the charge-rich treatment method is to add the imidazole type ionic liquid into a buffer solution and stir and mix, wherein the buffer solution is a mixture of 2-methacryloyloxyethyl trimethyl ammonium chloride and zinc dioxide at a mass ratio of 4:2, and then dispersed in water at a solid-liquid ratio of 1:14 g / mL; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a preheating temperature of 70° C. Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment, specifically, the sulfur-rich absorption reaction liquid is introduced into the air for heating reaction, and the reaction is carried out at a temperature of 120° C. for 65 minutes; the purified flue gas is obtained, and the absorption reaction liquid in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling; The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 3.99 g / Nm 3 The desulfurization rate is 97.6%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 95.9%.

[0016] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no pre-reaction agent is added to the absorption reaction liquid of Comparative Example 1, and the other conditions remain unchanged; The flue gas in this process is emitted from a coal-fired power plant with a SO2 concentration of 173.79 g / Nm3 The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 43.15g / Nm 3 The desulfurization rate is 75.2%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 65.14%.

[0017] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that no post-reaction agent is added to the absorption reaction liquid of Comparative Example 2, and the other conditions remain unchanged; The flue gas in this process is emitted from a coal-fired power plant with a SO2 concentration of 173.96 g / Nm 3 The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 49.25 g / Nm 3 The desulfurization rate is 71.6%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 63.5%.

[0018] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that no regeneration treatment is performed in Comparative Example 3, and the other conditions remain unchanged; The flue gas in this process is emitted from a coal-fired power plant with a SO2 concentration of 172.35 g / Nm 3 The SO2 concentration of the gas at the outlet of the regeneration tower was detected to be 4.13 g / Nm 3 The desulfurization rate is 97.6%, and the desulfurization rate after desulfurization treatment of 200kg flue gas is 75.25%.

[0019] 1. Testing the reaction absorption liquid prepared in Example A post-reaction reagent that was not subjected to charge enrichment treatment and reflux treatment was added as a control group of Example 1, and the reaction solution was tested using a dynamic light scattering instrument. The test results are shown in Table 1.

[0020] Table 1 Performance test of absorption reaction liquid Test groups Particle size of the reactant after reaction (nm) Potential difference between the pre-reaction agent and the post-reaction agent (mV) Example 1 108 40 Example 2 112 35 Example 3 105 40 Example 4 109 40 Example 5 113 38 Example 6 109 34 Control group 81 15 As can be seen from Table 1, the pre-reaction agent of the reaction absorption liquid in the absorption tower of the present invention has more negatively charged groups, and the post-reaction agent is a polymer system with a positive charge, forming a larger potential difference. The particle size of the post-reaction agent is larger, indicating that the post-reaction agent forms a polymer system with a skeleton.

[0021] 2. The absorption reaction liquid in the absorption tower of the embodiment and the comparative example was tested, and the test results are shown in Table 2.

[0022] Table 2 Performance of absorption reaction solution Test groups Absorption capacity g / kg Absorption capacity after 50 cycles of absorption g / kg Desorption rate of adsorbed sulfide / % Desorption rate of adsorbed sulfide after 50 cycles of absorption / % Example 1 251.65 246.88 99% 98% Example 2 248.14 242.31 98% 96% Example 3 245.05 240.25 99% 98% Example 4 250.33 233.96 97% 95% Example 5 245.74 238.53 97% 95% Example 6 247.63 237.35 98% 97% Comparative Example 1 210.91 178.47 78% 70% Comparative Example 2 193.54 179.18 77% 67% Comparative Example 3 250.36 149.35 98% 71% It can be seen from Table 2 that the wet desulfurization process of the present invention has a large absorption capacity, a high desorption and regeneration efficiency, and good process cycle stability.

[0023] It can be seen from the above experimental results that in the wet desulfurization process provided by the present invention, the absorption reaction liquid in the absorption tower is composed of an aqueous pre-reaction agent and a post-reaction agent. Through the diffusion effect of the absorption reaction liquid, the sulfide in the flue gas is reacted and fixed successively through negative charge complexation and positive charge adsorption. Compared with the reaction of a single reactant, the adsorption desulfurization effect is better. In the regeneration process, air is introduced and heated to promote the reaction to generate sulfur dioxide, and the desorption rate is high.

Claims

1. A wet desulfurization process for flue gas purification, characterized in that: The following steps are involved: Step 1: Treat the flue gas and pass it into the absorption reaction liquid in the absorption tower for reaction. After the reaction is completed, the sulfur-rich absorption reaction liquid obtained is pumped into the heat exchanger for heating; The absorption reaction liquid in the absorption tower is composed of a pre-reaction agent in the upper layer and a post-reaction agent in the lower layer in a volume ratio of 1:1-3; Step 2: preheating the heated sulfur-rich absorption reaction liquid in a preheater at a temperature of 60-80°C; Step 3: The preheated sulfur-rich absorption reaction liquid enters the regeneration tower for regeneration treatment to obtain purified flue gas, and the absorption reaction liquid in the regeneration tower passes through the heat exchanger and enters the absorption tower for recycling.

2. A wet desulfurization process for flue gas purification according to claim 1, characterized in that: The pre-reaction agent in step 1 is composed of a catalyst, ammonium polyphosphate and a carboxylate in a mass ratio of 3-5:15-19:1-3, and is dispersed in water in a solid-liquid ratio of 7-10:20-25 g / ml.

3. A wet desulfurization process for flue gas purification according to claim 2, characterized in that: The catalyst includes sodium hydroxymethane sulfonate.

4. A wet desulfurization process for flue gas purification according to claim 1, characterized in that: The post-reaction agent in step 1 comprises: by weight, 13-18 parts of ionic liquid, 1-3 parts of inorganic salt, 3-5 parts of polyamine compound, and 4-7 parts of histidine; the inorganic salt is one of sodium chloride, calcium chloride, and magnesium chloride.

5. A wet desulfurization process for flue gas purification according to claim 4, characterized in that: The ionic liquid is an imidazole-type ionic liquid treated with rich charges. The method for treating the rich charges is to add the imidazole-type ionic liquid into a buffer solution and stir and mix. The buffer solution is a mixture of 2-methacryloyloxyethyltrimethylammonium chloride and zinc dioxide in a mass ratio of 3-5:2, and then dispersed in water in a solid-liquid ratio of 1:10-14 g / mL.

6. A wet desulfurization process for flue gas purification according to claim 4, characterized in that: The preparation method of the post-reaction agent is as follows: the raw materials are mixed by weight and then ultrasonicated, stirred at an ultrasonic frequency of 10-20 KHz for 10-20 minutes, then heated to 60-70° C. in a reactor, refluxed for 8-10 hours, and then cooled to room temperature.

7. A wet desulfurization process for flue gas purification according to claim 1, characterized in that: The treatment in step 1 is to treat the flue gas in an electrostatic field strength of 0.1-0.6 V / m for 4-8 minutes.

8. A wet desulfurization process for flue gas purification according to claim 1, characterized in that: The reaction in step 1 is carried out at a pressure of 0.1-0.4 MPa for 20-30 min.

9. A wet desulfurization process for flue gas purification according to claim 1, characterized in that: The specific process of the regeneration treatment in step 3 is to introduce air into the sulfur-rich absorption reaction liquid for heating reaction.

10. A wet desulfurization process for flue gas purification according to claim 9, characterized in that: The heating reaction is carried out at a temperature of 100-120° C. for 50-70 minutes.

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