A method for removing hydrogen sulfide from industrial gases

Abstract

The present invention discloses a method for removing hydrogen sulfide from industrial gases, belonging to the field of hydrogen sulfide treatment. The method employs copper carbonate, copper hydroxide, and an oxygen-containing protonic acid as a composite desulfurization medium. Carbon dioxide generated in situ during the process is coupled with hypergravity to enhance the absorption and ionization reaction of hydrogen sulfide. The hydrogen sulfide absorption reaction and copper sulfide separation are simultaneously performed in a hypergravity reactor. This method has the advantages of rapid desulfurization, high desulfurization efficiency, a small equipment footprint, low investment costs, and the by-products of copper sulfide and gypsum. The process is more economical than complex iron methods and biological desulfurization methods.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen sulfide treatment, and in particular to a method for removing hydrogen sulfide from industrial gas. Background Art

[0002] Hydrogen sulfide is present in many industrial gases, including natural gas and biogas. Hydrogen sulfide is weakly acidic, and its presence can negatively impact subsequent applications of industrial gases, such as equipment corrosion and catalyst poisoning. For example, current methods for removing hydrogen sulfide from biogas in industry include biological desulfurization and complex iron desulfurization. These methods suffer from drawbacks such as large equipment footprint, slow desulfurization rates, and high costs. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention proposes a method for removing hydrogen sulfide from industrial gas.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for removing hydrogen sulfide from industrial gas comprises the following steps:

[0006] Copper carbonate, copper hydroxide and an oxygen-containing proton acid are used as composite desulfurization media to react with sulfur ions ionized by hydrogen sulfide dissolved in water in industrial gas. The ion reaction is as follows:

[0007] CuCO3+Cu(OH)2+4H + +2S 2- =2CuS↓+CO2↑+3H2O

[0008] The oxygen-containing proton acid includes but is not limited to sulfuric acid, nitric acid and perchloric acid.

[0009] Most of the copper sulfide is separated and extracted, and the remaining copper sulfide residue reacts with concentrated sulfuric acid to regenerate copper ions.

[0010] Optionally, the precipitation reaction and the separation and extraction of a portion of copper sulfide are carried out simultaneously in a supergravity machine.

[0011] Optionally, the other portion of the copper sulfide reacts with concentrated sulfuric acid, and the generated sulfur dioxide reacts with calcium hydroxide and oxygen to recover copper ions and produce gypsum as a by-product.

[0012] Optionally, the mass flow ratio of the liquid and gas of the super-heavy machine is controlled between 2-10.

[0013] Beneficial effects of the present invention:

[0014] 1. The present invention realizes the integrated operation of dissolution, ionization, precipitation and solid-liquid separation of gas, liquid and solid in the same super-heavy reactor. Compared with the traditional desulfurization process, the process is greatly shortened, the floor space is small and the equipment investment is small;

[0015] 2. The copper ions in the composite desulfurizer of the present invention are theoretically 100% recyclable. In actual operation, only a small amount of lost copper ions needs to be replenished to maintain the desulfurization load. No waste liquid is generated, and the process operating cost is very low.

[0016] 3. The revenue from the by-products of the present invention further increases the economic efficiency of the process, achieving the environmental and economic effects of turning waste into treasure;

[0017] 4. In the present invention, the sulfur element in hydrogen sulfide is ultimately fixed in the by-product copper sulfide or gypsum, and the hydrogen element in hydrogen sulfide is ultimately converted into hydrogen element in water molecules, without any secondary pollution products;

[0018] 5. The present invention adopts a composite desulfurization medium to absorb hydrogen sulfide. During the reaction between copper carbonate and oxygen-containing protonic acid, carbon dioxide is generated in situ. The continuous bubbling of carbon dioxide produces a large vapor-liquid interface, which greatly promotes the dissolution and ionization of hydrogen sulfide and the precipitation reaction rate of sulfur ions and copper ions. The copper hydroxide in the composite desulfurization medium plays a dual role of providing copper ions and adjusting the pH value of the solution.

[0019] 6. The present invention overcomes the defects of slow biological desulfurization speed in the industry, and also overcomes the defects of large area occupation and poor desulfurization effect of the existing complex iron desulfurization in the industry. It has the advantages of fast desulfurization speed, high desulfurization efficiency (greater than 99.9%), low operating cost and investment cost. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0021] In some examples of the present invention, a method for removing hydrogen sulfide from industrial gas is disclosed, the method comprising the following steps:

[0022] S1: Composite desulfurization medium undergoes ionization reaction with hydrogen sulfide

[0023] The ionic reaction equation is as follows:

[0024] H2S(g)=H2S(aq) (1)

[0025] H2S(aq)=H ++HS - (2)

[0026] HS - =H + +S 2- (3)

[0027] CuCO3+Cu(OH)2+4H + +2S 2- =2CuS↓+CO2↑+3H2O (4)

[0028] Since the ionic product of copper sulfide is very small, Ksp CuS is 6×10 -36 This characteristic ensures that the sulfur ions ionized from the hydrogen sulfide dissolved in water undergo a rapid precipitation reaction. Since this reaction is very easy to occur (can be regarded as an irreversible reaction), it promotes the rapid ionization reactions (2) and (3) of the hydrogen sulfide dissolved in the water phase.

[0029] Therefore, both the precipitation reaction and the ionization reaction are fast reactions, and the removal rate of hydrogen sulfide in industrial gas is actually controlled by the dissolution rate of hydrogen sulfide in the aqueous phase, that is, formula (1) is the desulfurization control step.

[0030] The dissolution rate of hydrogen sulfide is mainly related to the gas-liquid contact mode, gas pressure, temperature, etc. If the gas pressure and temperature are fixed, strengthening the gas-liquid contact and increasing the gas-liquid mass transfer coefficient are effective ways to accelerate the dissolution rate of hydrogen sulfide.

[0031] The present invention uses two coupled methods to enhance gas-liquid contact and accelerate the desulfurization rate. First, copper carbonate reacts with hydrogen ions to continuously release carbon dioxide gas through in-situ bubbling, which promotes the dissolution and ionization of hydrogen sulfide. Second, a super-heavy machine reactor is used. Under the centrifugal force generated by high-speed rotation, the liquid phase is sheared into countless tiny droplets, resulting in a huge liquid surface. The gas-liquid contact mass transfer and reaction are greatly enhanced. After the above coupling and strengthening measures, the mass transfer rate and reaction rate of the desulfurization of the present invention are increased by more than 100 times compared with conventional alkaline solution desulfurization.

[0032] S2: Sedimentation online separation

[0033] The copper sulfide precipitate generated by the reaction is separated into solid and liquid online under the huge centrifugal force of the supergravity reactor. After discharge, the liquid phase returns to the supergravity reactor for recycling. The solid phase is the copper sulfide precipitate. After purification, high-purity copper sulfide (purity greater than 99%) is obtained and sold as a high-value-added chemical product. The copper sulfide with lower purity is sent to the next regeneration device for regeneration.

[0034] S3: Copper ion regeneration and sulfur dioxide fixation

[0035] The following reactions occur in the regeneration reactor:

[0036] CuS+4H2SO4(concentrated)=Cu 2+ +SO4 2- +4SO2↑+4H2O (5)

[0037] The generated copper ion solution is input into the precipitation reaction process of S1 for recycling, and the sulfur dioxide gas discharged from the regeneration reactor is absorbed by lime milk slurry, while oxidation reaction and hydration reaction are carried out simultaneously to prepare calcium sulfate dihydrate (gypsum) by-product.

[0038] 2Ca(OH)2+2SO2+O2=2CaSO4+2H2O (6)

[0039] CaSO4+2H2O=CaSO4·2H2O (7)

[0040] From the reaction principle explained above, it can be seen that theoretically, 100% of the copper ions are recycled (most of them are recovered as high-value-added copper sulfide products, and the rest are recycled), the hydrogen ions in the hydrogen sulfide are converted into hydrogen ions, and finally converted into hydrogen ions in water and removed; most of the sulfur ions in the hydrogen sulfide are fixed in the copper sulfide, and the rest are fixed in the gypsum by-product.

[0041] In some examples of the present invention, the mass flow ratio of the liquid (with water as the solvent) and the gas of the loaded composite desulfurization medium entering the super-heavy machine is controlled between 2 and 10 to ensure a sufficiently large liquid dispersion interface, the molar ratio of copper carbonate to copper hydroxide in the inlet desulfurization medium is controlled between 1:3 and 1:5, the particle size of the mixture of copper carbonate and copper hydroxide is controlled to be less than 0.2 mm, and the molar number of hydrogen ions of the oxygen-containing proton acid in the desulfurization medium is controlled to be 1.05-1.1 times the molar number of copper atoms therein to ensure that the dissolved hydrogen sulfide is fully precipitated in the precipitation reaction;

[0042] In some examples of the present invention, the molar ratio of concentrated sulfuric acid to copper sulfide in the regeneration reactor is controlled between 4.1 and 4.5, with a slight excess of concentrated sulfuric acid to ensure that the copper atoms in the copper sulfide are completely converted into copper ions and to avoid incomplete reaction of residual copper sulfide;

[0043] In some examples of the present invention, the amount of copper hydroxide added during the precipitation reaction is controlled to maintain the pH of the reaction solution at neutral.

[0044] In some examples of the present invention, copper carbonate, copper hydroxide and an oxygen-containing proton acid are used as composite desulfurization media to react with sulfur ions ionized by hydrogen sulfide dissolved in water in industrial gas. The ion reaction is:

[0045] CuCO3+Cu(OH)2+4H + +2S 2- =2CuS↓+CO2↑+3H2O

[0046] Most of the copper sulfide is separated and extracted, and the remaining copper sulfide residue reacts with concentrated sulfuric acid to regenerate copper ions.

[0047] To verify the removal effect of hydrogen sulfide, the present invention discloses the following specific examples:

[0048] Example 1

[0049] Industrial gas 1 contains 2546.5 ppm of hydrogen sulfide, the main gas components of which are methane and a small amount of nitrogen. The method of the present invention is used to remove hydrogen sulfide therefrom. The industrial gas feed is 600 mL / min, the copper ion concentration in the composite desulfurization medium is maintained at 0.5 mol / L, the desulfurization liquid flow rate is maintained at 35 g / min, the supergravity factor of the supergravity machine reactor is 101.5, the total residence time of the gas in the liquid is controlled at 30 min, and the gas outlet detection shows that the hydrogen sulfide concentration is reduced to 15.6 ppm.

[0050] Example 2

[0051] Industrial gas 2 contains 300 ppm of hydrogen sulfide, the main gas components of which are hydrogen and carbon monoxide. The method of the present invention is used to remove hydrogen sulfide therefrom. The industrial gas is fed at 70 mL / min, the copper ion concentration in the composite desulfurization medium is maintained at 0.3 mol / L, the desulfurization liquid flow rate is maintained at 25 g / min, the supergravity factor of the supergravity machine reactor is 99.2, the total residence time of the gas in the liquid is controlled at 13 minutes, and gas outlet detection shows that the hydrogen sulfide concentration is reduced to below 10 ppm.

[0052] Example 3

[0053] Industrial gas 3 contains 3580 ppm of hydrogen sulfide, the main gas components of which are methane and carbon dioxide. The method of the present invention is used to remove hydrogen sulfide therefrom. The industrial gas feed rate is 700 mL / min, the copper ion concentration in the composite desulfurization medium is maintained at 0.89 mol / L, the desulfurization liquid flow rate is maintained at 57 g / min, the supergravity factor of the supergravity machine reactor is 112.3, the total residence time of the gas in the liquid is controlled at 35 min, and the gas outlet detection shows that the hydrogen sulfide concentration is reduced to 18.6 ppm.

[0054] Throughout this specification, references to terms such as "embodiment," "example," and "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0055] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for removing hydrogen sulfide from industrial gas, characterized in that: The following steps are involved: Copper carbonate, copper hydroxide and an oxygen-containing proton acid are used as composite desulfurization media to react with sulfur ions ionized by hydrogen sulfide dissolved in water in industrial gas. The ion reaction is as follows: CuCO3+Cu(OH)2+4H + +2S 2- =2CuS↓+CO2↑+3H2O Part of the copper sulfide is separated and extracted, and the remaining copper sulfide residue reacts with concentrated sulfuric acid to regenerate copper ions; The ion reaction and the separation and extraction of part of the copper sulfide are carried out simultaneously in the high-gravity reactor. The liquid loaded with the composite desulfurization medium entering the high-gravity reactor uses water as a solvent. In the ion reaction, copper carbonate reacts with hydrogen ions to continuously release carbon dioxide gas to promote the dissolution and ionization of hydrogen sulfide.

2. The method for removing hydrogen sulfide from industrial gas according to claim 1, characterized in that: The sulfur dioxide generated by the reaction of the remaining copper sulfide residue with concentrated sulfuric acid reacts with calcium hydroxide and oxygen to obtain copper ions and produce calcium sulfate dihydrate as a by-product.

3. The method for removing hydrogen sulfide from industrial gas according to claim 1, characterized in that: In the reaction of copper sulfide and concentrated sulfuric acid, the molar ratio of sulfuric acid to copper sulfide is controlled between 4.1 and 4.

5.

4. The method for removing hydrogen sulfide from industrial gas according to claim 1, characterized in that: The mass flow ratio of liquid to gas in the high gravity reactor is controlled between 2-10.

5. The method for removing hydrogen sulfide from industrial gas according to claim 1, characterized in that: The following steps are also included: The copper ions produced by the composite desulfurizer are used as precipitants to react with hydrogen sulfide in industrial gas dissolved in water to produce copper sulfide. Oxygen-containing proton acid is added to react with copper sulfide to regenerate the copper ions. The generated sulfur dioxide is absorbed by calcium hydroxide solution and fixed as calcium sulfate.