An organic amine desulfurizer effective in reducing foaming problems

Abstract

The application discloses an organic amine desulfurizer capable of effectively reducing foaming problems, which is composed of 5-60wt% main absorbent, 2-40wt% auxiliary absorbent, 2-30wt% additive and 30-60wt% water; wherein the main absorbent is one or more than one of a double-hydroxyalkyl piperazine organic amine, the auxiliary absorbent is one or more than one of a single-alkyl piperazine organic amine and a single-hydroxyalkyl piperazine organic amine, and the additive comprises 1.8-29.8wt% acid, 0.1-2wt% antioxidant and 0.1-2wt% defoaming agent; the addition amount of the acid is adjusted according to the pH of the organic amine desulfurizer being 5-6. The foaming problem of the organic amine in the use process is effectively solved through the collocation of the main absorbent and the auxiliary absorbent, and the absorption-desorption comprehensive performance of the desulfurizer is improved.

Description

Technical Field

[0001] This invention relates to the field of desulfurization technology, and in particular to a composite organic amine desulfurizing agent for cyclically removing SO2 from flue gas (tail gas) to be treated. Background Technology

[0002] Currently, industrial methods for treating sulfuric acid tail gas mainly include wet and semi-dry methods. These methods typically have drawbacks such as low byproduct utilization value, potential secondary pollution, complex operating procedures, and difficulty in achieving lower tail gas levels. Regenerative and recyclable desulfurization methods have become a research hotspot both domestically and internationally. Organic amine desulfurization technology uses amine liquid as an SO2 absorbent, completing the desulfurization task through absorption and desorption processes. This technology exhibits good selectivity for SO2 absorption, a wide adaptability to flue gas sulfur content, and the absorbent is regenerable and recyclable. The product is 99% high-purity SO2, which can be used to produce liquid SO2 or sulfur, and has a stable market and sales channels. Organic amine flue gas desulfurization technology has promising development prospects.

[0003] Among the more successful renewable wet flue gas desulfurization technologies, Kang Shifu's CANSOLV flue gas desulfurization technology is a good example. This technology uses a diamine as the absorbent, neutralizes one of the strongly basic amine groups with a strong acid, and uses the other weak amine group as the main functional group for sulfur dioxide absorption.

[0004] Studies have found that piperazine organic amines have advantages over ethylenediamine and alkanolamines, such as higher boiling point, less solvent evaporation loss, and less corrosion to equipment.

[0005] In practical applications of organic amine desulfurization, foaming and liquid retention of the amine solution are common problems. These phenomena lead to the formation of mist entrainment in the absorption tower, causing a large amount of desulfurizing agent to be carried away by the airflow, resulting in amine loss. In severe cases, it can also cause flooding in the absorption tower, leading to pressure fluctuations, reduced tray efficiency, and poorer separation performance. Reducing the foaming problem of the amine solution has become the key to the widespread application of this technology.

[0006] Chinese invention patent “A renewable flue gas desulfurizer and its application” (CN201210449283.9) discloses 1,4-bis(2-hydroxypropyl)piperazine as the main component of the desulfurizer. Its preparation process is simple and has the advantages of high desorption rate and low energy consumption in the cycle process.

[0007] Chinese invention patent “A renewable organic amine flue gas desulfurizer and its preparation method” (CN201310673132.6) discloses 1-(2-hydroxyethyl)-4-(2-hydroxypropyl)piperazine as the main component of the flue gas (tail gas) desulfurizer to be treated. Its synthesis and separation process is simple and it is not easy to crystallize.

[0008] However, all of the above-mentioned flue gas desulfurizing agents have the problem of being prone to foaming and difficult to defoam. Summary of the Invention

[0009] To address the foaming problem of organic amines during use and improve the overall absorption-desorption performance of desulfurizers, this invention provides an organic amine desulfurizer that effectively reduces foaming issues.

[0010] This invention provides an organic amine desulfurizer that effectively reduces foaming problems, comprising 5-60 wt% main absorbent, 2-40 wt% supplementary absorbent, 2-30 wt% additives, and 30-60 wt% water; wherein:

[0011] The main absorbent is one or more of the dihydroxyalkylpiperazine organic amines, and its content in the organic amine desulfurizer is preferably 30-50 wt%, and most preferably 30-40 wt%.

[0012] The absorbent is one or more of monoalkylpiperazine organic amines and monohydroxyalkylpiperazine organic amines, and its content in the organic amine desulfurizer is preferably 5-20 wt%, and most preferably 5-15 wt%.

[0013] The additives include 1.8-29.8 wt% acid, 0.1-2 wt% antioxidant and 0.1-2 wt% defoamer (based on the total weight of the organic amine desulfurizer), wherein the amount of acid added is adjusted to adjust the pH of the organic amine desulfurizer to 5-6.

[0014] The organic amine desulfurizer, which effectively reduces foaming problems, is prepared by mixing and stirring the main absorbent, the supplementary absorbent, the additives and water evenly.

[0015] The organic amine desulfurizer provided by this invention has a low foaming height, a fast defoaming speed, and a desorption rate of more than 95%.

[0016] The further defined technical solution is as follows:

[0017] The primary absorbent may be one or more of dihydroxyalkylpiperazine and dihydroxyalkylpiperazinone, wherein the hydroxyalkyl group is preferably C1-C3 hydroxyalkyl, specifically for example: N,N-dihydroxymethylpiperazine, N,N-dihydroxyethylpiperazine, N,N-dihydroxypropylpiperazine, N,N-dihydroxymethylpiperazinone, N,N-dihydroxyethylpiperazinone, and N,N-dihydroxypropylpiperazinone.

[0018] The absorbent can be a monoalkylpiperazine, a monohydroxyalkylpiperazine, a monoalkylpiperazinone, or a monohydroxyalkylpiperazinone, wherein the alkyl group is preferably C1-C3 alkyl, and the hydroxyalkyl group is preferably C1-C3 hydroxyalkyl, specifically, for example: N-methylpiperazine, N-ethylpiperazine, N-propylpiperazine, N-hydroxymethylpiperazine, N-hydroxyethylpiperazine, N-hydroxypropylpiperazine, N-methylpiperazinone, N-ethylpiperazinone, N-propylpiperazinone, N-hydroxymethylpiperazinone, N-hydroxyethylpiperazinone, N-hydroxypropylpiperazinone.

[0019] The acid is one or more selected from phosphoric acid, boric acid, citric acid, nitric acid, sulfuric acid, and hydrochloric acid. For ease of use and cost reduction, the acid is more preferably phosphoric acid and / or sulfuric acid, and particularly preferably sulfuric acid.

[0020] The antioxidant may be one or more selected from sodium sulfite, copper acetate, tert-butylhydroquinone, hydroquinone, dodecyl hydroquinone, anthraquinone disulfonic acid, and sodium anthraquinone disulfonate, preferably one or more selected from sodium sulfite, anthraquinone, tert-butylhydroquinone, and hydroquinone. Based on the total weight of the organic amine desulfurizer, the content of the antioxidant may be 0.1-2 wt%, preferably 0.1-1 wt%.

[0021] The defoamer may be one or more of polydimethylsiloxane, ethylene glycol siloxane, and polyoxypropylene ethylene glycerol ether, preferably polydimethylsiloxane, with a content of 0.1-2 wt% (based on the total weight of the organic amine desulfurizer).

[0022] The preparation method of the organic amine desulfurizer that effectively reduces foaming problems according to the present invention is as follows: add the main absorbent, the supplementary absorbent, the antioxidant and the defoamer to water and stir to dissolve, then adjust the pH value to 5-6 with acid, and then add water to make up the volume to obtain the organic amine desulfurizer.

[0023] The organic amine desulfurizer of the present invention has a suitable absorption temperature of 30-50℃, especially at 30-40℃, where the liquid viscosity is relatively high, and the present invention has a significant gain effect.

[0024] The organic amine desulfurizer of the present invention is suitable for (0.1-2):1 (L:m 3 The optimal liquid-to-gas ratio absorption condition is (0.9-2):1 (L:m³). 3 The higher the liquid-to-gas ratio, the more significant the gain effect of this invention.

[0025] The beneficial technical effects of this invention are reflected in the following aspects:

[0026] The organic amine in the main absorbent of this invention contains two hydroxyl groups, which have good water solubility and low vapor pressure, and contains two amine groups, which have a large absorption capacity.

[0027] Dihydroxyalkylpiperazine aqueous solutions are characterized by high viscosity and low surface tension. In practical applications, they are prone to foaming and slow defoaming, which leads to the formation of mist entrainment in the absorption tower. This causes a large amount of desulfurizing agent to be carried away by the airflow, resulting in amine liquid loss. In severe cases, it can also cause liquid flooding in the absorption tower, causing tower pressure fluctuations, reducing tower tray efficiency, and deteriorating separation effect.

[0028] The addition of monoalkylpiperazine and / or monohydroxyalkylpiperazine components to the absorbent can effectively increase the surface tension of the solution, reduce the time required for defoaming, and have little impact on the SO2 absorption capacity of the organic amine solution.

[0029] After absorbing SO2, the main absorbent component and the supplementary absorbent component are easily oxidized by oxygen in the flue gas to form thermally stable salts. These thermally stable salts adsorb onto the bubble surface, thereby reducing the surface tension of the solution and making the bubbles more stable. This invention can effectively reduce the formation of thermally stable salts. Excessive antioxidants can also easily form stable bubbles; therefore, the amount of antioxidant added should not exceed 2 wt%, and preferably not exceed 1 wt%. Detailed Implementation

[0030] The present invention will be further described below with reference to the embodiments.

[0031] Example 1

[0032] 40 g of N,N-bis(2-hydroxyethyl)piperazine and 5 g of N-hydroxypropylpiperazinone (total amine concentration 45%) were combined, along with 0.5 g of hydroquinone and 1 g of polydimethylsiloxane, and dissolved in 40 g of distilled water. Sulfuric acid was added to adjust the pH to 5.6, and then distilled water was added to bring the total volume to 100 g. The foaming height of the desulfurization solution was measured to be 20 mm, and the defoaming time was 3 s.

[0033] Take 50 mL of the above solution and absorb it at 40℃. After the absorbent reaches saturation, perform thermal desorption at 110℃, controlling the total flow rate of the mixed gas at 500 mL / min and the SO2 concentration at 4000 mg / Nm³. 3 The SO2 content in the purified gas is 25 mg / Nm³. 3 .

[0034] In this embodiment, the desulfurizing agent was regenerated after absorption saturation. After 10 repetitions, the foaming height of the desulfurization liquid was measured to be 30 mm, and the defoaming time was 5 s. In the control group, a 45% N,N-bis(2-hydroxyethyl)piperazine aqueous solution was used as the desulfurizing agent. 0.5 g of hydroquinone was added, dissolved in 40 g of distilled water, and sulfuric acid was added to adjust the pH to 5.6 before adding distilled water to a final volume of 100 g. Before absorption, the foaming height of the desulfurization liquid was measured to be 25 mm, and the defoaming time was 4 s. After 10 experiments, the foaming height of the desulfurization liquid was 80 mm, and the defoaming time was 11 s.

[0035] Example 2

[0036] 25 g of N,N-bis(2-hydroxymethyl)piperazine and 10 g of N-hydroxypropylpiperazine (total amine concentration 35%) were combined, along with 1 g of tert-butylhydroquinone and 1 g of polydimethylsiloxane, and dissolved in 40 g of distilled water. Sulfuric acid was added to adjust the pH to 5.8, and then distilled water was added to bring the total volume to 100 g. The foaming height of the desulfurization solution was measured to be 10 mm, and the defoaming time was 2 s.

[0037] Take 50 mL of the above solution and absorb it at 35℃. After the absorbent reaches saturation, perform thermal desorption at 110℃, controlling the total flow rate of the mixed gas at 500 mL / min and the SO2 concentration at 5000 mg / Nm³. 3 The SO2 content in the purified gas is 40 mg / Nm³. 3 .

[0038] In this embodiment, the desulfurizing agent was regenerated after absorption saturation. After 10 repetitions, the foaming height of the desulfurization liquid was measured to be 25 mm, and the defoaming time was 4 s. In the control group, a 35% N,N-bis(2-hydroxymethyl)piperazine aqueous solution was used as the desulfurizing agent. 1 g of tert-butylhydroquinone was added, dissolved in 40 g of distilled water, and the pH was adjusted to 5.8 with sulfuric acid. Then, distilled water was added to bring the total volume to 100 g. Before absorption, the foaming height of the desulfurization liquid was measured to be 20 mm, and the defoaming time was 3.5 s. After 10 experiments, the foaming height of the desulfurization liquid was 70 mm, and the defoaming time was 10 s.

[0039] Example 3

[0040] 40 g of N,N-bis(2-hydroxypropyl)piperazine was combined with 5 g of N-hydroxypropylpiperazine and 5 g of N-hydroxyethylpiperazine (total amine concentration 50%), 0.05 g of tert-butylhydroquinone, and 1 g of polyoxypropylene ethylene glycol ether, and then dissolved in 40 g of distilled water. Sulfuric acid was added to adjust the pH to 5.8, and then distilled water was added to bring the total volume to 100 g. The foaming height of the desulfurization solution was measured to be 40 mm, and the defoaming time was 4 s.

[0041] Take 50 mL of the above solution and absorb it at 40℃. After the absorbent reaches saturation, perform thermal desorption at 110℃, controlling the total flow rate of the mixed gas at 500 mL / min and the SO2 concentration at 3000 mg / Nm³. 3 The SO2 content in the purified gas is 10 mg / Nm³. 3 .

[0042] In this embodiment, the desulfurizing agent was regenerated after absorption saturation. After 10 repetitions, the foaming height of the desulfurization liquid was measured to be 5 mm, and the defoaming time was 6 s. In the control group, a 50% N,N-bis(2-hydroxypropyl)piperazine aqueous solution was used as the desulfurizing agent. 0.05 g of tert-butylhydroquinone was added, dissolved in 40 g of distilled water, and the pH was adjusted to 5.8 with sulfuric acid. Then, distilled water was added to bring the total volume to 100 g. Before absorption, the foaming height of the desulfurization liquid was measured to be 70 mm, and the defoaming time was 8 s. After 10 experiments, the foaming height was 15 mm, and the defoaming time was 13 s.

[0043] In practical applications, the specific substances and contents of the main absorbent, supplementary absorbent, and additives can be changed, and the foaming problem can be effectively solved within the mass concentration range of each component.

Claims

1. An organic amine desulfurizer that effectively reduces foaming problems, comprising 30-50 wt% main absorbent, 5-20 wt% supplementary absorbent, 2-30 wt% additives, and 30-60 wt% water; wherein, The main absorbent is one or more of the dihydroxyalkylpiperazine organic amines, and the supplementary absorbent is a monoalkylpiperazine organic amine or a combination of monoalkylpiperazine and monohydroxyalkylpiperazine organic amines. The addition of the supplementary absorbent increases the surface tension of the solution and reduces the time required for defoaming. The additives include 1.8-29.8 wt% acid, 0.1-2 wt% antioxidant, and 0.1-2 wt% defoamer, wherein the amount of acid added is adjusted to adjust the pH of the organic amine desulfurizer to 5-6.

2. The organic amine desulfurizer as described in claim 1, characterized in that, The primary absorbent is selected from one or more of bis(hydroxyalkyl)piperazine and bis(hydroxyalkyl)piperazinone.

3. The organic amine desulfurizer as described in claim 2, characterized in that, The primary absorbent is selected from one or more of N,N-dihydroxymethylpiperazine, N,N-dihydroxyethylpiperazine, N,N-dihydroxypropylpiperazine, N,N-dihydroxymethylpiperazinone, N,N-dihydroxyethylpiperazinone, and N,N-dihydroxypropylpiperazinone.

4. The organic amine desulfurizer as described in claim 1, characterized in that, The absorbent is selected from one or more of monoalkylpiperazine, monohydroxyalkylpiperazine, monoalkylpiperazinone, and monohydroxyalkylpiperazinone.

5. The organic amine desulfurizer as described in claim 4, characterized in that, The absorbent is selected from one or more of N-methylpiperazine, N-ethylpiperazine, N-propylpiperazine, N-hydroxymethylpiperazine, N-hydroxyethylpiperazine, N-hydroxypropylpiperazine, N-methylpiperazinone, N-ethylpiperazinone, N-propylpiperazinone, N-hydroxymethylpiperazinone, N-hydroxyethylpiperazinone, and N-hydroxypropylpiperazinone.

6. The organic amine desulfurizer according to claim 1, characterized in that, The acid is one or more of phosphoric acid, boric acid, citric acid, nitric acid, sulfuric acid, and hydrochloric acid.

7. The organic amine desulfurizer as described in claim 1, characterized in that, The antioxidant is selected from one or more of sodium sulfite, copper acetate, tert-butylhydroquinone, hydroquinone, dodecylhydroquinone, anthraquinone disulfonic acid, and sodium anthraquinone disulfonic acid.

8. The organic amine desulfurizer as described in claim 1, characterized in that, The defoamer is selected from one or more of polydimethylsiloxane, ethylene glycol siloxane, and polyoxypropylene ethylene glycerol ether.

9. A method for effectively reducing foaming problems in organic amine desulfurizers, comprising adding an absorbent to an organic amine desulfurizer with a dihydroxyalkylpiperazine organic amine as the main absorbent to increase the surface tension of the solution and reduce the time required for defoaming; characterized in that, The absorbent is a monoalkylpiperazine organic amine or a combination of monoalkylpiperazine and monohydroxyalkylpiperazine organic amines; the organic amine desulfurizer consists of 30-50 wt% main absorbent, 5-20 wt% absorbent, 2-30 wt% additives, and 30-60 wt% water; wherein the additives include 1.8-29.8 wt% acid, 0.1-2 wt% antioxidant, and 0.1-2 wt% defoamer, wherein the amount of acid added is to adjust the pH of the organic amine desulfurizer to 5-6; the main absorbent, absorbent, antioxidant, and defoamer are added to water and stirred to dissolve, then the pH is adjusted to 5-6 with acid, and then water is added to make up the volume to obtain the organic amine desulfurizer.

10. The method as described in claim 9, characterized in that, The primary absorbent is selected from one or more of bis(hydroxyalkyl)piperazine and bis(hydroxyalkyl)piperazinone.

11. The method as described in claim 10, characterized in that, The primary absorbent is selected from one or more of N,N-dihydroxymethylpiperazine, N,N-dihydroxyethylpiperazine, N,N-dihydroxypropylpiperazine, N,N-dihydroxymethylpiperazinone, N,N-dihydroxyethylpiperazinone, and N,N-dihydroxypropylpiperazinone.

12. The method as described in claim 9, characterized in that, The absorbent is selected from one or more of monoalkylpiperazine, monohydroxyalkylpiperazine, monoalkylpiperazinone, and monohydroxyalkylpiperazinone.

13. The method as described in claim 12, characterized in that, The absorbent is selected from one or more of N-methylpiperazine, N-ethylpiperazine, N-propylpiperazine, N-hydroxymethylpiperazine, N-hydroxyethylpiperazine, N-hydroxypropylpiperazine, N-methylpiperazinone, N-ethylpiperazinone, N-propylpiperazinone, N-hydroxymethylpiperazinone, N-hydroxyethylpiperazinone, and N-hydroxypropylpiperazinone.

14. The method as described in claim 9, characterized in that, The acid is one or more of phosphoric acid, boric acid, citric acid, nitric acid, sulfuric acid, and hydrochloric acid.

15. The method as described in claim 9, characterized in that, The antioxidant is selected from one or more of sodium sulfite, copper acetate, tert-butylhydroquinone, hydroquinone, dodecylhydroquinone, anthraquinone disulfonic acid, and sodium anthraquinone disulfonic acid.

16. The method as described in claim 9, characterized in that, The defoamer is selected from one or more of polydimethylsiloxane, ethylene glycol siloxane, and polyoxypropylene ethylene glycerol ether.