Method for extracting salt from coal chemical raw gas desulfurization barren liquor

Abstract

The invention relates to the technical field of desulfurization barren liquor salt extraction, in particular to a coal chemical raw gas desulfurization barren liquor salt extraction method. The method comprises the following steps: step 1, a preparation stage: preparing experimental apparatuses, wherein the experimental apparatuses comprise a 500mL measuring cylinder, a balance, a vacuum pump, a Buchner funnel, a drying oven, a conductivity meter and an ion chromatograph; the desulfurization barren solution and the desalting agent are mixed and stirred three times according to different proportions, and three different turbid solutions are obtained.According to the method for extracting salt from the raw gas desulfurization barren solution in the coal chemical industry, the alcohol-containing solvent and the desulfurization barren solution are mixed according to the proportion, so that a large number of salt substances can be separated out, and the salt substances are separated out; wherein 81% of sodium sulfate and 74.8% of total salt in the barren solution can be extracted according to the ratio of the desalting agent to the barren solution being 1: 1, so that the problem that the hydrogen production desulfurization barren solution is high in salt enrichment is solved, the operation efficiency of a desulfurization system is improved, and the stability and reliability of the salt extraction effect are improved through detailed experimental steps and control over all links, so that the production efficiency of the coal chemical industry is improved.

Description

Technical Field

[0001] The invention relates to the technical field of salt extraction from desulfurized lean liquid, and in particular to a method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas. Background Art

[0002] In the coal chemical production process, hydrogen production and desulfurization lean liquid plays an important role. However, there are some problems in hydrogen production and desulfurization lean liquid. The sodium sulfate content in hydrogen production and desulfurization lean liquid is usually 130-170g / L, the sodium thiosulfate content is 20-60g / L, the sodium thiocyanate content is 0.1-5g / L, the sodium bicarbonate content is 10-40g / L, and the sodium carbonate content is 1-10g / L. The high salt content will lead to the need to add a large amount of catalyst. In order to suppress the increase of salt content, not only the desulfurization effect is deteriorated, but also the amount of alkali added is increased, which will lead to increased costs. Specifically, there are the following disadvantages:

[0003] First, the salt content of the hydrogen production desulfurization lean liquid is high, which easily increases the burden of desulfurization lean liquid salt extraction operation; second, the desulfurization effect is poor, affecting the quality and efficiency of coal chemical production; third, pipeline corrosion is aggravated, which not only increases the cost of equipment maintenance and replacement, but also reduces the safety and stability of the production system; fourth, the increase in production costs, including factors such as increased catalyst usage and increased alkali addition, all make production costs difficult to control, thereby reducing the stability and reliability of production.

[0004] In view of this, there is an urgent need for a method for extracting salt from the desulfurization lean liquid of coal chemical waste gas. Summary of the invention

[0005] The object of the present invention is to provide a method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides a method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas, comprising the following steps:

[0007] S1. Preparation stage: prepare experimental equipment, including 500mL measuring cylinder, balance, vacuum pump, Buchner funnel, oven, conductivity meter and ion chromatograph; prepare raw materials, including desulfurization lean solution and desalting agent;

[0008] S2, stirring and salt extraction: mixing and stirring the desulfurized lean solution and the desalting agent in different proportions for three times to obtain three different turbid solutions;

[0009] S3, filtration separation: connect the three different turbid solutions to the Buchner funnel through a vacuum pump for filtration to separate the salt particles from the solution, collect the separated salt particles and filtrate, and store them in different containers respectively;

[0010] S4, drying: the collected salt particles are evenly spread on the tray of the oven, and the oven is turned on for drying. During the drying process, the state of the salt particles is observed to completely remove the water and the desalting agent;

[0011] S5, desalting agent recovery: distill the filtrate obtained by suction filtration and observe the temperature change during the distillation process. When the first drop of desalting agent flows out, start collecting the desalting agent and continue heating and distilling until the temperature reaches 83°C, then stop heating and complete the distillation work;

[0012] S6, reuse: the distilled salt extracting agent is mixed with the desulfurization lean liquid again in a ratio of 1:1 to perform salt extraction operation, and the stirring salt extraction in S2, the suction filtration separation in S3, the drying in S4 and the desalting agent recovery steps in S5 are repeated. At the same time, the bottom solution after distillation is transported to the desulfurization tower for reuse because the sodium bicarbonate content therein is 10-20g / L;

[0013] S7. Analysis: Record and analyze each experimental result in detail.

[0014] As a further improvement of the technical solution, in S1, the desulfurized lean liquid includes sodium sulfate, sodium thiosulfate, sodium bicarbonate, sodium carbonate and sodium thiocyanate, among which sodium sulfate has the highest content, and the desulfurized lean liquid also includes DSH catalyst and PDS catalyst;

[0015] The desalting agent includes an alcohol-containing solvent as a main component, and the alcohol-containing solvent includes methanol.

[0016] As a further improvement of the technical solution, in S2, the three different proportions of desulfurized lean liquid and desalting agent include the following three operations:

[0017] First, 200 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 260 g, and the total dissolved solid content was 61 g / L. Salt particles precipitated and the solution was turbid.

[0018] Second, 400 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 234 g, and the total dissolved solid content was 61 g / L. Salt particles precipitated and the solution was turbid.

[0019] Third, 100 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 234 g, and the total dissolved solid content was 61 g / L. Salt particles precipitated and the solution was turbid.

[0020] As a further improvement of the technical solution, in S4, the oven drying temperature is 105°C.

[0021] As a further improvement of the technical solution, in S4, the oven drying time is 3h-5h.

[0022] As a further improvement of the technical solution, in S5, when the first drop of desalting agent flows out, the temperature reaches 68°C-75°C.

[0023] As a further improvement of the present technical solution, in S7, the experimental results are recorded and analyzed in detail including the mass of precipitated salt, filtrate TDS, total salt removal rate, sodium sulfate content and changes in various salt components.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. In the method for extracting salt from the desulfurization lean liquid of the coal chemical industry, a large amount of salt substances can be precipitated by mixing the alcohol-containing solvent with the desulfurization lean liquid in proportion, wherein 81% of the sodium sulfate and 74.8% of the total salt in the lean liquid can be extracted at a ratio of 1:1 between the desalting agent and the lean liquid. This solves the problem of high salt content in the hydrogen production desulfurization lean liquid and improves the operating efficiency of the desulfurization system. At the same time, the detailed experimental steps and the control of each link improve the stability and reliability of the salt extraction effect, thereby improving the production efficiency of the coal chemical industry.

[0026] 2. In the method of extracting salt from the lean liquid of desulfurized coal gas in the coal chemical industry, the risk of pipeline corrosion is reduced by reducing the content of sodium sulfate, which not only reduces the cost of equipment maintenance and replacement, but also improves the safety and stability of the production system. In addition, the effective removal of salt substances also reduces safety hazards such as leakage caused by corrosion, improves production safety, and at the same time, improves environmental protection, thereby reducing the potential pollution of the environment by corrosion products.

[0027] 3. The method for extracting salt from the lean liquid of the coal chemical industry waste gas desulfurization reduces production costs and realizes resource recycling. On the one hand, by controlling the amount of desalting agent and the distillation temperature, the amount of evaporation and the amount of alcohol-containing solvent are reduced, thereby improving economic benefits. On the other hand, the bottom solution after distillation contains a certain amount of sodium bicarbonate, which can be transported to the desulfurization tower for reuse, further reducing production costs. At the same time, it does not affect the content of the two desulfurization catalysts, avoiding the input of additional catalysts, thereby improving resource utilization efficiency, reducing environmental pollution, and enhancing the stability and safety of the production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flowchart of the method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas. DETAILED DESCRIPTION

[0029] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] according to Figure 1 As shown, the embodiment of the present invention provides a method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas, comprising the following steps:

[0031] Step 1, preparation stage: prepare experimental equipment, including 500mL measuring cylinder, balance, vacuum pump, Buchner funnel, oven, conductivity meter and ion chromatograph; prepare raw materials, including desulfurization lean liquid and desalting agent; desulfurization lean liquid includes sodium sulfate, sodium thiosulfate, sodium bicarbonate, sodium carbonate and sodium thiocyanate, among which sodium sulfate has the highest content, and desulfurization lean liquid also includes DSH catalyst and PDS catalyst;

[0032] The desalting agent includes an alcohol-containing solvent as a main component, and the alcohol-containing solvent includes methanol;

[0033] Step 2: Stirring and extracting salt: Mix and stir the desulfurized lean solution and desalting agent in different proportions for three times to obtain three different turbid solutions; the three different proportions of desulfurized lean solution and desalting agent include the following three operations:

[0034] First, 200 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 260 g, and the total dissolved solid (TDS) content was 61 g / L. Salt particles were precipitated and the solution was turbid.

[0035] Second, 400 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 234 g, and the total dissolved solid (TDS) content was 61 g / L. Salt particles precipitated and the solution was turbid.

[0036] Third, 100 mL of desalting agent and 200 mL of desulfurized lean solution were mixed and stirred for 3 min. The desulfurized lean solution weighed 234 g, and the total dissolved solid (TDS) content was 61 g / L. Salt particles precipitated and the solution was turbid.

[0037] Step 3, filtration separation: connect the three different turbid solutions to the Buchner funnel through a vacuum pump for filtration to separate the salt particles from the solution, collect the separated salt particles and the filtrate, and store them in different containers respectively;

[0038] Step 4, drying: evenly spread the collected salt particles on the tray of the oven, turn on the oven for drying, the oven drying temperature is 105 ° C, the oven drying time is 3h-5h, when the salt particles no longer have obvious moisture, the appearance is dry and the weight no longer changes significantly, it can be considered that the drying is completed. During the drying process, observe the state of the salt particles to completely remove water and desalting agent;

[0039] Step 5, desalting agent recovery: the filtrate obtained by suction filtration separation is distilled, and the temperature change during the distillation process is observed. When the first drop of desalting agent flows out, the temperature reaches 68°C-75°C, and the alcohol-containing solvent (desalting agent) begins to flow out of the distillation device in the form of a liquid. The first drop of liquid substance is identified as a sign that the desalting agent begins to be evaporated. The desalting agent is collected and heated and distilled until the temperature reaches 83°C. The heating is stopped and the distillation work is completed. A balance can be achieved in terms of desalting agent recovery efficiency, energy consumption, and impact on subsequent treatment. For example, if the temperature continues to rise, other impurities that are more difficult to separate may also be evaporated in large quantities, increasing the difficulty of subsequent treatment; or unnecessary energy consumption may be increased while the incremental amount of recovered desalting agent is not obvious. Stopping the heating when the temperature is below 83°C may result in insufficient recovery of the desalting agent, affecting the efficiency and economy of the entire salt extraction process;

[0040] Step 6: Reuse: The distilled salt extracting agent is mixed with the desulfurization lean liquid again in a ratio of 1:1 to perform salt extraction operation, and the stirring salt extraction in S2, the suction filtration separation in S3, the drying in S4 and the desalting agent recovery steps in S5 are repeated. At the same time, the bottom solution after distillation is transported to the desulfurization tower for reuse because the sodium bicarbonate content therein is 10-20g / L, so as to further reduce production costs and realize the recycling of resources, and can effectively extract 81% of sodium sulfate and 74.8% of total salt in the desulfurization lean liquid;

[0041] Step 7. Analysis: Record and analyze each experimental result in detail. The experimental results should include the mass of precipitated salt, filtrate TDS, total salt removal rate, sodium sulfate content and changes in various salt components.

[0042] First, alcohol-containing solvents are used as desalting agents and mixed with desulfurization lean liquid in a certain proportion. This not only allows salt particles to precipitate, effectively solving the problem of high salt content in hydrogen production desulfurization lean liquid, but also helps reduce the risk of pipeline corrosion, such as reducing sodium sulfate corrosion on pipelines. It can also effectively improve the recycling effect of resources, transport the distilled bottom solution to the desulfurization tower for reuse, and reduce production costs.

[0043] The reaction mechanism is that after the alcohol-containing solvent (such as methanol) is mixed with the desulfurized lean liquid, the polarity, solubility and other properties of the solution are changed, so that the solubility of the salt substances (such as sodium sulfate, sodium thiosulfate, etc.) therein is reduced and precipitated to form salt particles. In the drying process, high temperature is used to volatilize water and desalting agent to obtain dry salt particles. The distillation process utilizes the difference in boiling points between the alcohol-containing solvent and other substances to evaporate and recover the alcohol-containing solvent by heating, while avoiding the evaporation of large amounts of other impurities.

[0044] By mixing the alcohol-containing solvent with the desulfurization lean liquid in proportion, a large amount of salt substances can be precipitated. Among them, the desalting agent and the lean liquid can extract 81% of the sodium sulfate and 74.8% of the total salt in the lean liquid at a ratio of 1:1. This solves the problem of high salt content in the hydrogen production desulfurization lean liquid and improves the operating efficiency of the desulfurization system. At the same time, the detailed experimental steps and the control of each link improve the stability and reliability of the salt extraction effect, thereby improving the production efficiency of coal chemical industry.

[0045] By reducing the sodium sulfate content, the risk of pipeline corrosion is reduced, which not only reduces the cost of equipment maintenance and replacement, but also improves the safety and stability of the production system. In addition, the effective removal of salt substances also reduces safety hazards such as leakage caused by corrosion, improves production safety, and at the same time, improves environmental protection, thereby reducing potential pollution to the environment due to corrosion products.

[0046] The method for extracting salt from the desulfurization lean liquid of the coal chemical industry waste gas reduces production costs and realizes resource recycling. On the one hand, by controlling the amount of desalting agent and the distillation temperature, the evaporation amount and the alcohol-containing solvent amount are reduced, thereby improving economic benefits. On the other hand, the bottom solution after distillation contains a certain amount of sodium bicarbonate, which can be transported to the desulfurization tower for reuse, further reducing production costs. At the same time, it does not affect the content of the two desulfurization catalysts, avoiding the input of additional catalysts, thereby improving resource utilization efficiency, reducing environmental pollution, and enhancing the stability and safety of the production system.

[0047] According to different raw material dosages, the antibacterial composite desulfurization lean liquid salt extraction provided by the present invention is further illustrated by the following specific examples.

[0048] Example 1

[0049] The volume ratio of desalting agent to lean liquid is 1:2

[0050] Experimental process: 200mL of desalting agent and 200mL of desulfurized lean liquid (weight 260g, TDS 61g / L) were mixed and stirred for 3min, and then filtered, dried, and desalting agent was recovered.

[0051] Results: The average drying mass of precipitated salt was 27.2g, the average TDS of the filtrate after distillation was 29.4mg / L, the total salt removal rate was 51.8%, the average sodium sulfate content of the filtrate after distillation was 44.32g / L, the sodium carbonate in the desulfurization liquid after salt extraction was 4.1g / L, the sodium bicarbonate was 16.9g / L, the catalyst DSH was 0.4g / L, and the PDS was 19.0mg / L.

[0052] Example 2

[0053] The volume ratio of desalting agent to lean liquid is 1:1

[0054] Experimental process: Take a desalting agent with an equal volume to the desulfurized lean liquid and mix it with the desulfurized lean liquid and stir for 3 minutes, and then perform the same operation steps;

[0055] Results: The average drying mass of precipitated salt was 39.2g, the average TDS of the filtrate after distillation was 15.4mg / L, the total salt removal rate was 74.8%, the average sodium sulfate content of the filtrate after distillation was 30.2g / L, the sodium carbonate in the desulfurization liquid after salt extraction was 4.1g / L, the sodium bicarbonate was 16.9g / L, the catalyst DSH was 0.4g / L, and the PDS was 19.0mg / L.

[0056] Example 3

[0057] The volume ratio of desalting agent to lean liquid is 2:1

[0058] Experimental process: Take 400mL of desalting agent and 200mL of desulfurized lean liquid, mix and stir for 3 minutes, and then carry out each step.

[0059] Results: The average drying mass of precipitated salt was 42.6g, the average TDS of the filtrate after distillation was 9.9mg / L, the total salt removal rate was 83.8%, the average sodium sulfate content of the filtrate after distillation was 2.66g / L, the sodium carbonate in the desulfurization liquid after salt extraction was 2.1g / L, the sodium bicarbonate was 9.8g / L, the catalyst DSH was 0.2g / L, and the PDS was 16.1mg / L.

[0060] Table 1 Salt components after drying of desalting agent and lean solution in a ratio of 1:1

[0061]

[0062] Table 2 Desalting agent and lean solution 1:1 ratio filtrate salt components

[0063]

[0064] In order to verify that the salt extraction method prepared in the embodiment of the present invention has good effectiveness and stability, the method for extracting salt from the coal chemical industry waste gas desulfurization lean liquid provided in the embodiment of the present invention is described through the following test examples.

[0065] Test example

[0066] The purpose of this test group is to explore the effect of different component ratios on salt extraction from desulfurized lean liquid.

[0067] Test objectives: To detect the total salt removal rate, precipitated salt quality, filtrate TDS, sodium sulfate content, the impact on the content of sodium carbonate and sodium bicarbonate, and the impact on the content of two catalysts, etc., in order to verify the effectiveness and stability of the salt extraction method.

[0068] Test method: Test group A, test group B and test group C respectively adopt the composition ratio of salt extraction from desulfurized lean solution provided in Examples 1-3; the control example adopts control group A and control group B, wherein:

[0069] Control group A

[0070] Original desulfurized lean liquid without salt extraction treatment;

[0071] Control group B

[0072] Desulfurized lean liquid after treatment by evaporation separation method.

[0073] Specific detection indicators are shown in Table 3.

[0074] Table 3 Test indicators of each sample

[0075]

[0076] As shown in Table 3, the method for extracting salt from the lean liquid of coal chemical industry waste gas desulfurization of the present invention is compared with the traditional evaporation separation method (control group B) and the original desulfurized lean liquid without salt extraction treatment (control group A). ​​It can be seen that at a ratio of 1:1 between the desalting agent and the lean liquid, the total salt removal rate is as high as 74.8%, which is much higher than 28.4% of the control group A and 52.9% of the control group B; the average sodium sulfate content of the filtrate after distillation is 30.2 g / L, which is lower than 89.6 g / L of the control group A and 37.8 g / L of the control group B. At the same time, in terms of the sodium carbonate recycling content, the catalyst DSH and PDS content, the present method has less fluctuation than the control group, and does not affect the expensive desulfurization catalyst content. In terms of the amount of alcohol-containing solvent and the evaporation heat, the energy consumption can be reduced due to the precise control of the distillation temperature;

[0077] In summary, the salt extraction method of the present invention effectively solves the problem of high salt content in the hydrogen production desulfurization lean liquid by adopting the steps of mixing and stirring the alcohol-containing solvent and the desulfurization lean liquid in a certain proportion, separating by suction filtration, drying and recovering the desalting agent, reduces the risk of pipeline corrosion, improves resource utilization efficiency, reduces production costs, and has good economic and environmental benefits.

[0078] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas, characterized in that: The following steps are involved: S1. Preparation stage: prepare experimental equipment, including 500mL measuring cylinder, balance, vacuum pump, Buchner funnel, oven, conductivity meter and ion chromatograph; prepare raw materials, including desulfurization lean solution and desalting agent; S2, stirring and salt extraction: mixing and stirring the desulfurized lean solution and the desalting agent in different proportions for three times to obtain three different turbid solutions; S3, filtration separation: connect the three different turbid solutions to the Buchner funnel through a vacuum pump for filtration to separate the salt particles from the solution, collect the separated salt particles and filtrate, and store them in different containers respectively; S4, drying: the collected salt particles are evenly spread on the tray of the oven, and the oven is turned on for drying. During the drying process, the state of the salt particles is observed to completely remove the water and the desalting agent; S5, desalting agent recovery: distill the filtrate obtained by suction filtration and observe the temperature change during the distillation process. When the first drop of desalting agent flows out, start collecting the desalting agent and continue heating and distilling until the temperature reaches 83°C, then stop heating and complete the distillation work; S6, reuse: the distilled salt extracting agent is mixed with the desulfurization lean liquid again in a ratio of 1:1 to perform salt extraction operation, and the stirring salt extraction in S2, the suction filtration separation in S3, the drying in S4 and the desalting agent recovery steps in S5 are repeated. At the same time, the bottom solution after distillation is transported to the desulfurization tower for reuse because the sodium bicarbonate content therein is 10-20g / L; S7. Analysis: Record and analyze each experimental result in detail.

2. The method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas according to claim 1, characterized in that: In S1, the desulfurized lean liquid includes sodium sulfate, sodium thiosulfate, sodium bicarbonate, sodium carbonate and sodium thiocyanate, among which sodium sulfate has the highest content, and the desulfurized lean liquid also includes DSH catalyst and PDS catalyst; The desalting agent includes an alcohol-containing solvent as a main component, and the alcohol-containing solvent includes methanol.

3. The method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas according to claim 1, characterized in that: In S2, the three different ratios of desulfurized lean liquid and desalting agent include the following three operations: First, 200 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 260 g, and the total dissolved solid content was 61 g / L. Salt particles were precipitated and the solution was turbid. Second, 400 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 234 g, and the total dissolved solid content was 61 g / L. Salt particles precipitated and the solution was turbid. Third, 100 mL of desalting agent and 200 mL of desulfurized lean liquid were mixed and stirred for 3 minutes. The desulfurized lean liquid weighed 234 g, and the total dissolved solid content was 61 g / L. Salt particles precipitated and the solution was turbid.

4. The method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas according to claim 1, characterized in that: In S4, the oven drying temperature is 105°C.

5. The method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas according to claim 1, characterized in that: In S4, the oven drying time is 3h-5h.

6. The method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas according to claim 1, characterized in that: In S5, when the first drop of desalting agent flows out, the temperature reaches 68°C-75°C.

7. The method for extracting salt from desulfurized lean liquid of coal chemical industry waste gas according to claim 1, characterized in that: In S7, the experimental results are recorded and analyzed in detail, including the mass of precipitated salt, filtrate TDS, total salt removal rate, sodium sulfate content and changes in various salt components.

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