Two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas and preparation method thereof

Abstract

The invention discloses a two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas and a preparation method thereof, the two-phase absorbent comprises the following components in percentage by mass: 40-70% of a phase-splitting agent, 10-40% of an alcohol amine chemical absorbent, 2-6% of AMP, 2-6% of piperazine and the balance of water, and the sum of the mass percentages of the components is 100%. The preparation method of the two-phase absorbent specifically comprises the following steps: mixing the diethanol amine and the sulfolane, sequentially adding the piperazine, the AMP and the water, and stirring for 1-2 minutes to prepare a solution, namely the two-phase absorbent. When the two-phase absorbent is in contact with blast furnace gas, H2S, CO2 and COS in a gas phase are subjected to a physical and chemical reaction with an absorbent liquid phase, simultaneous removal of H2S, CO2 and COS is achieved, the total S in purified gas is lower than 20 mg / Nm < 3 >, the CO2 capture rate is larger than 90%, and meanwhile the two-phase absorbent has good corrosion resistance and thermal stability.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial gas purification material preparation, and in particular relates to a two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas, and also relates to a preparation method of the two-phase absorbent. Background Art

[0002] Blast furnace gas is a combustible gas produced as a byproduct of the blast furnace ironmaking process. Its main components are carbon monoxide, carbon dioxide, nitrogen, hydrogen and hydrocarbons, and it also contains a small amount of hydrogen chloride, H2S, organic sulfur (mainly carbonyl sulfide (COS)) and dust. Blast furnace gas has a large volume and a carbon dioxide content of about 18%. It also has a certain calorific value. It is often transported to downstream user units such as blast furnace hot blast furnaces, steel rolling heating furnaces, boiler steam power generation, etc., and used as fuel for subsequent applications. The sulfur content is converted into sulfur dioxide after combustion and discharged with the flue gas to form pollution. Under the policy of ultra-low emissions throughout the entire process of the steel industry, fine desulfurization of coal gas at the front end is the best treatment solution.

[0003] Common desulfurization and decarbonization absorbents include monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), diisopropanolamine (DIPA), sterically hindered amine 2-amino-2-methyl-1-propanol (AMP) and other alcoholamine reagents and mixed amine absorbents of various alcoholamines. However, single alcoholamine absorbents have obvious limitations in meeting the needs of industrial desulfurization and decarbonization, and cannot meet the requirements of efficient and stable treatment effects.

[0004] AMP absorbent is a hot topic in current research. It has excellent performance in CO2 capture and H2S removal. 1 mol of AMP can absorb 1 mol of carbon dioxide, which exceeds the 0.5 mol CO2 / mol that can be absorbed by primary and secondary amines. In addition, a series of mixed amine absorbents can match the corresponding process flow for different working conditions to improve the desulfurization and decarbonization efficiency. The Sulfinol series of solvents developed by Shell Company in the United States include Sulfinol-D solvent (sulfolane (SF) + DIPA + water) and Sulfinol-M solvent (sulfolane + MDEA + water). Sulfinol-D solvent can remove CO2 in a wide concentration range and deeply remove organic sulfur, while Sulfinol-M solvent can selectively remove H2S in CO2 gas.

[0005] Although the above methods can achieve the removal of H2S, CO2 and organic sulfur, the efficiency of simultaneous removal of the three gases is very low in the actual process, especially the absorption effect of organic sulfur (COS) is not ideal, there is a large selective absorption, and most of the above absorbents are homogeneous aqueous solution absorption systems. Due to the large specific heat capacity and low boiling point of water, there is a problem of high regeneration energy consumption when the absorbent is used for desulfurization carbon capture.

[0006] As a new type of absorbent, two-phase absorbent can separate phases during the absorption process. After absorbing the gas, the homogeneous absorbent separates into a heterogeneous solution of rich phase and lean phase. Desorbing the rich phase alone can effectively reduce energy consumption. There have been a lot of reports on the absorption of CO2 by two-phase absorbents, but there are few two-phase absorbents that simultaneously absorb acidic gases. Summary of the invention

[0007] The object of the present invention is to provide a two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas, which can efficiently carry out simultaneous desulfurization and decarbonization of blast furnace gas.

[0008] Another object of the present invention is to provide a method for preparing a two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas.

[0009] The technical solution adopted by the present invention is that the two-phase absorbent used for simultaneous desulfurization and carbon capture of blast furnace gas includes the following components by mass percentage: 40%-70% phase separation agent, 10%-40% alcohol amine chemical absorbent, 2%-6% AMP, 2%-6% piperazine, and the balance is water, and the total mass percentage of the above components is 100%.

[0010] The present invention is also characterized in that:

[0011] The phase separation agent is specifically sulfolane.

[0012] The alcoholamine absorbent is specifically diethanolamine.

[0013] Another technical solution adopted by the present invention is a method for preparing a two-phase absorbent for simultaneous desulfurization of blast furnace gas and carbon capture, which is specifically: firstly, diethanolamine and cyclopentane sulfone are mixed, and then piperazine, AMP and water are added in sequence, and stirred for 1 to 2 minutes at a stirring temperature of 30 to 50°C to prepare a solution, which is a two-phase absorbent.

[0014] The beneficial effects of the present invention are:

[0015] The two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas of the present invention, when in contact with blast furnace gas, H2S, CO2 and COS in the gas phase undergo physical and chemical reactions with the absorbent, achieving simultaneous removal of H2S, CO2 and COS, and the total S in the purified gas is less than 20 mg / Nm 3 , CO2 capture rate is greater than 90%, the solution forms a lean and rich liquid-liquid two-phase, most of the H2S, CO2 and COS reactants after the reaction are retained in the rich liquid with a smaller volume, and the desorption process only needs to be implemented on the rich liquid, thereby greatly reducing the desorption energy consumption. At the same time, the absorbent has good corrosion resistance and thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1A schematic diagram of a performance evaluation device for desulfurization carbon capture using the absorbent of the present invention;

[0017] Figure 2 It is a curve diagram of H2S removal rate of absorbents with different ratios;

[0018] Figure 3 It is a curve diagram of H2S absorption by absorbents with different ratios;

[0019] Figure 4 The figure is a curve diagram of COS removal rate of absorbents with different ratios;

[0020] Figure 5 It is a curve diagram of COS absorption by absorbents with different ratios;

[0021] Figure 6 The graph is a graph showing the CO2 removal rate of absorbents with different ratios;

[0022] Figure 7 This is a curve chart of the CO2 absorption capacity of absorbents with different ratios.

[0023] In the figure, 1. gas cylinder, 2. pressure reducing valve, 3. mass flow controller, 4. water bath, 5. Monteggia washing bottle, 6. electronic soap film flowmeter, 7. tail gas absorption device (ferric chloride), 8. first connecting pipe, 9. second connecting pipe, 10. gas chromatograph, 11. computer. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The invention is used for the carbon capture two-phase absorbent for simultaneous desulfurization of blast furnace gas, which comprises the following components by mass percentage: 40%-70% phase separation agent, 10%-40% alcohol amine chemical absorbent, 2%-6% AMP, 2%-6% piperazine, and the balance is water, and the total mass percentage of the above components is 100%.

[0026] The phase separation agent is sulfolane; the alcoholamine absorbent is diethanolamine;

[0027] As a phase separation agent, sulfolane (SF) has good solubility and can effectively separate other components when absorbing CO2, thereby improving separation efficiency. At the same time, sulfolane also has good phase separation characteristics, thermal stability and chemical stability, and can maintain stable performance in complex industrial environments.

[0028] Diethanolamine (DEA) is a secondary amine with low cost, and the product generated by its reaction with CO2 is relatively stable. The generated carbamate can be easily decomposed under heating conditions, thereby achieving the desorption of CO2.

[0029] In order to promote the removal effect of the mixed solution composed of cyclopentane and ethanolamine on H2S, CO2 and COS components, the active additives used in the present invention are AMP and piperazine (PZ), wherein AMP is a sterically hindered amine, and the stability of the carbamate ion generated by the reaction with CO2 is weak, and it is easy to hydrolyze the bicarbonate ion to achieve efficient removal of CO2. Piperazine, as a cyclic amine with a symmetrical structure, has the characteristics of fast reaction rate, heat resistance, good degradability, etc.

[0030] When the two-phase absorbent of the present invention is compounded with blast furnace gas, DEA / AMP / PZ will react with H2S to generate HS by protonating the N atom in the structure. - The quaternary ammonium salt of the group absorbs CO2 and COS mainly according to the zwitterion mechanism, and generates carbamate ions, thiocarbamate ions, etc. after chemical absorption. The products after absorption are mainly enriched in the upper phase of the solution, and by promoting the phase separation of the system, H2S, CO2, and COS are deeply removed.

[0031] The preparation method of the blast furnace gas simultaneous desulfurization carbon capture two-phase absorbent of the present invention is: firstly, diethanolamine and cyclopentane are mixed in a Montex washing bottle, active components and water are added, and stirred for 1 to 2 minutes to prepare a solution, namely the two-phase absorbent.

[0032] like Figure 1 As shown, the gas of the simulated blast furnace gas cylinder 1 is decompressed by the pressure reducing valve 2, flows through the mass flow controller 3 and is immersed in the Monte Carlo washing bottle 5 in the constant temperature magnetic stirring water bath 4, and then enters the electronic soap film flowmeter 6, and the outlet gas flows into the tail gas absorption device 7, and then the tail gas is emptied through the exhaust pipe. The gas before and after absorption is collected into the gas chromatograph 10 through the first connecting pipe 8 and the second connecting pipe 9 for detection, and the gas chromatograph 10 is connected to the computer 11 for outputting the data after feedback analysis. The Monte Carlo washing bottle 5 specifically adopts a 100mL flask, which is filled with the prepared absorption liquid. The medium in the tail gas absorption device is ferric chloride.

[0033] Comparative Example 1

[0034] The absorbent is composed of the following components by mass percentage: 60% SF, 10% DEA, and the balance is water, and the total mass percentage of the above components is 100%.

[0035] Comparative Example 2

[0036] The absorbent is composed of the following components by mass percentage: 50% SF, 20% DEA, and the balance is water, and the total mass percentage of the above components is 100%.

[0037] Comparative Example 3

[0038] The absorbent consists of the following components by mass percentage: 60% SF, 30% DEA, and the balance is water, and the total mass percentage of the above components is 100%.

[0039] Comparative Example 4

[0040] The absorbent is composed of the following components by mass percentage: 60% SF, 20% DEA, and the balance is water, and the total mass percentage of the above components is 100%.

[0041] Comparative Example 5

[0042] The absorbent is composed of the following components by mass percentage: 60% SF, 15% DEA, and the balance is water, and the total mass percentage of the above components is 100%.

[0043] Comparative Example 6

[0044] The absorbent is composed of the following components by mass percentage: 70% SF, 20% DEA, and the balance is water, and the total mass percentage of the above components is 100%.

[0045] Example 1

[0046] The absorbent is composed of the following components by mass percentage: 60% SF, 20% DEA, 6% AMP, and the balance is water, and the total mass percentage of the above components is 100%.

[0047] Example 2

[0048] The absorbent consists of the following components by mass percentage: 60% SF, 20% DEA, 5% PZ, and the balance is water, and the total mass percentage of the above components is 100%.

[0049] Example 3

[0050] The absorbent is composed of the following components by mass percentage: 60% SF, 20% DEA, 6% AMP, 5% PZ, and the balance is water, and the total mass percentage of the above components is 100%.

[0051] The components of simulated blast furnace gas are shown in Table 1:

[0052] Table 1 Simulated blast furnace gas components

[0053] composition <![CDATA[H2S]]> COS <![CDATA[CO2]]> CO <![CDATA[N2]]> v / v(%) <![CDATA[200mg / m 3 ]]> <![CDATA[210mg / m 3 ]]> ～27％ ～17％ ～55％

[0054] During the experiment, 100 mL of the prepared absorbent was placed in a Monterey bottle, and the water bath was turned on to stir and preheat to 40°C. The mass flow meter was adjusted to control the CO2 inlet flow rate to 500 mL / min, and the absorption was continued for 0.5 h.

[0055] The absorbent components and rich phase ratio, absorption load and maximum absorption capacity of each embodiment and comparative example are listed in Table 2.

[0056] Table 2 Absorption results of the absorbents in Comparative Examples 1-6

[0057]

[0058] By comparing and selecting the best phase change system 60% SF+20% DEA+20% H2O, adding active additives AMP / PZ and studying the absorption effect of CO2 / H2S / COS in blast furnace gas. Experimental conditions were set as follows: reaction temperature 40℃, inlet gas flow rate 100mL / min, solution volume 100mL.

[0059] The absorbent components and the removal rates of H2S, CO2 and COS of each of Examples 1-3 and Comparative Example 4 are listed in Table 3;

[0060] Table 3 Removal rate of absorbent components of Examples 1-3 and Comparative Example 4

[0061]

[0062] As can be seen from Table 3, the removal efficiency of the absorbent in Comparative Example 4 is relatively low. At 120 minutes, the CO2 removal rate dropped to 46.31%. When 5% PZ was added alone to the mixed amine solution, the COS removal rate of the absorbent remained above 85%; when the sterically hindered amine AMP was added alone, the H2S removal rate remained above 95%; the H2S removal rate and absorption amount of absorbents with different ratios were different. Figure 2 and Figure 3 As shown in the figure, different ratio systems have different COS removal rates and absorption amounts. Figure 4 and Figure 5 As shown in Figure 2, different ratio systems have different effects on CO2 removal rate and absorption capacity. Figure 6 and Figure 7 As shown in the figure, it can be seen that the absorbent of Example 3 of the present invention, by adding a limited amount of AMP and piperazine to the mixed alcohol amine solution to form a composite absorbent, achieves the common deep removal of H2S, CO2 and COS, and the removal efficiency is higher than 85%.

Claims

1. A two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas, characterized in that: The components include the following by mass percentage: 40%-70% phase separation agent, 10%-40% alcohol amine chemical absorbent, 2%-6% AMP, 2%-6% piperazine, and the balance is water, and the total mass percentage of the above components is 100%.

2. The two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas according to claim 1, characterized in that: The phase separation agent is specifically sulfolane.

3. The two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas according to claim 1, characterized in that: The alcoholamine absorbent is specifically diethanolamine.

4. The method for preparing a two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas according to claim 1, characterized in that: Specifically, the phase separation agent and the alcohol amine chemical absorbent are first mixed, and then piperazine, AMP and water are added in sequence, and stirred to obtain a two-phase absorbent.

5. The method for preparing a two-phase absorbent for simultaneous desulfurization and carbon capture of blast furnace gas according to claim 4, characterized in that: The stirring temperature is 30-50°C and the stirring time is 1-2 minutes.

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