Method for improving dry desulfurization removal efficiency in carbon dioxide capture process and application

Abstract

The invention relates to a method for improving the removal efficiency of dry desulfurization in a carbon dioxide trapping process and application, and belongs to the technical field of trapping, utilization and storage of carbon dioxide. The method comprises the steps of raw material gas injection, pre-desulfurization tower pretreatment, hydrolysis tower desulfurization treatment and fine desulfurization tower adsorption treatment. Hydrogen sulfide is oxidized into sulfur and sulfate which are easier to adsorb through oxygen in dry air, so that the adsorption and capture efficiency is improved; meanwhile, oxygen in the dry air oxidizes carbonyl sulfide into hydrogen sulfide and sulfur dioxide which are easier to treat, the desulfurization efficiency is improved, and feed gas with the sulfur content smaller than 0.1 ppm is finally obtained and is greatly improved compared with the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, utilization and storage, and specifically relates to a method and application of improving dry desulfurization removal efficiency in a carbon dioxide capture process. Background Art

[0002] With the increasing pressure of global warming and carbon emission reduction, carbon dioxide capture, utilization and storage (CCUS) technology has become one of the important means to achieve the dual carbon goals. The coal chemical industry is one of the main sources of carbon emissions. CCUS technology can not only effectively reduce carbon dioxide emissions, but also apply the captured carbon dioxide to oil field exploitation. Increasing the oil recovery rate of oil fields through carbon dioxide flooding technology is an important means in the modern chemical industry.

[0003] However, the carbon dioxide discharged by the coal chemical industry has a high sulfur content. During the carbon dioxide oil recovery process, sulfur will cause the interaction between carbon dioxide and crude oil to become complicated, reducing the solubility of carbon dioxide in the oil layer and thus weakening its oil recovery ability. Sulfides will also react chemically with minerals in the oil layer to form precipitates, further blocking the oil layer and reducing the permeability of the reservoir. At the same time, sulfides will also corrode equipment pipelines under high temperature and high pressure, causing equipment damage and pollution source leakage, which will not only increase the maintenance cost of the equipment but also pollute the environment and ecology. Therefore, the exhaust gas needs to be desulfurized.

[0004] Existing dry desulfurization generally uses hydrolysis to convert carbonyl sulfide into hydrogen sulfide and then adsorbs it through activated carbon. However, the desulfurization efficiency of this method is not high (about 90%), and the sulfur content in the final raw gas is generally greater than 1ppm. In order to improve the desulfurization efficiency, a method is needed to convert carbonyl sulfide and hydrogen sulfide in the gas into sulfides that are easier to handle to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a method for improving the dry desulfurization removal efficiency in a carbon dioxide capture process, by converting impurities in the raw gas into sulfides that are easier to handle, thereby improving the desulfurization efficiency and significantly reducing the sulfur content in the raw gas.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for improving dry desulfurization removal efficiency in a carbon dioxide capture process, characterized in that it comprises the following steps: S1: Injecting raw gas: introducing raw gas and dry air into the system through a compressor; S2: Pretreatment in pre-desulfurization tower: After the raw gas and dry air enter the pre-desulfurization tower, the hydrogen sulfide in the raw gas undergoes an oxidation-reduction reaction with the desulfurizer in the pre-desulfurization tower, converting the hydrogen sulfide into elemental sulfur and water, preliminarily reducing the concentration of hydrogen sulfide in the raw gas to obtain pretreated raw gas; S3: Desulfurization treatment in a hydrolysis tower: The pretreated raw gas obtained in step S2 is sequentially introduced into two hydrolysis towers, wherein the hydrolysis towers include a hydrolysis layer and a first adsorption layer, wherein a hydrolysis catalyst is arranged in the hydrolysis layer, and carbonyl sulfide in the pretreated raw gas undergoes hydrolysis reaction in the hydrolysis layer to be converted into hydrogen sulfide, and the first adsorption layer adsorbs and removes the generated hydrogen sulfide, and finally obtains a desulfurized raw gas; S4: adsorption treatment in a fine desulfurization tower: the desulfurized raw gas obtained in step S3 is passed into a fine desulfurization tower, which includes two upper and lower second adsorption layers. The residual hydrogen sulfide, heavy metals, and organic impurities in the desulfurized raw gas are removed through the desulfurization adsorption layers to obtain finished raw gas; Among them, in steps S2-S4, the oxygen in the dry air oxidizes hydrogen sulfide into more easily adsorbed sulfur and sulfate to improve the adsorption capture efficiency; at the same time, the oxygen in the dry air oxidizes carbonyl sulfide into more easily handled hydrogen sulfide and sulfur dioxide to improve the desulfurization efficiency.

[0007] Furthermore, the first adsorption layer and the second adsorption layer include activated carbon.

[0008] Furthermore, the desulfurizing agent is ferric oxide.

[0009] Furthermore, the hydrolysis catalyst is aluminum oxide.

[0010] Furthermore, the sulfur content of the finished raw gas is less than 0.1 ppm.

[0011] The beneficial effects of the present invention are: 1. High-efficiency desulfurization capacity: Through the combined action of the pre-desulfurization tower and the hydrolysis desulfurization tower, the process can effectively convert sulfides such as COS in the raw gas into H2O that is easy to handle. 2 S, and then the residual hydrogen sulfide and other impurities are further removed through the adsorption of activated carbon. This multi-stage desulfurization mechanism ensures efficient desulfurization effect, so that the total sulfur content in the final raw gas can be stably controlled below 0.1ppm.

[0012] 2. Energy saving and environmental protection: The hydrolysis reaction is exothermic, which is conducive to maintaining the temperature of the reaction system and reducing the need for external heating, thereby saving energy. At the same time, due to the high adsorption performance of activated carbon, the process can simultaneously remove impurities such as organic matter and heavy metals, which not only improves the purity of the raw gas, but also reduces potential pollution to the environment.

[0013] 3. Stable and reliable operation: The hydrolysis + dry desulfurization process has a reasonable process design, and the connections between the units are close, which can ensure continuous and stable operation. In addition, the service life of adsorption materials such as activated carbon is long, which reduces the frequency of material replacement and reduces maintenance costs.

[0014] 4. Strong adaptability: This process can process raw gas containing different types and concentrations of sulfides and has strong adaptability. 2 Both S and COS can be effectively removed through corresponding reactions and adsorption processes.

[0015] 5. High product quality: After fine desulfurization, the raw gas has H 2 The content of S and other impurities is extremely low, which can meet the needs of high-purity carbon dioxide capture projects and ensure the stable operation of subsequent processes and the reliability of product quality.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flow chart of a method for improving dry desulfurization removal efficiency in a carbon dioxide capture process shown in one embodiment of the present invention.

[0018] Figure 2 This is a comparison diagram of the application of a method for improving dry desulfurization removal efficiency in a carbon dioxide capture process shown in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] Dry desulfurization technology mainly uses solid absorbent or catalyst to chemically react with sulfide in the raw gas (CO2 waste gas) to achieve desulfurization. However, the removal of hydrogen sulfide and carbonyl sulfide has the following difficulties: 1. Hydrogen sulfide has strong reducing properties and is difficult to be effectively captured by conventional absorbents; 2. Carbonyl sulfide is weakly acidic and requires special desulfurization methods or conditions to achieve a high removal efficiency; 3. Carbonyl sulfide is easily reduced to hydrogen sulfide during conventional desulfurization, resulting in a decrease in desulfurization efficiency.

[0020] During the carbon dioxide recovery process, the total sulfur content in carbon dioxide will have a series of impacts on the recovery process, which are directly related to many aspects such as recovery effect, equipment corrosion, safety and environmental protection.

[0021] First, if the total sulfur content in carbon dioxide is too high, it will directly affect the oil recovery efficiency. The presence of sulfur will complicate the interaction between carbon dioxide and crude oil, reduce the solubility of carbon dioxide in the oil layer, and thus weaken its oil recovery ability. In addition, sulfur will also chemically react with minerals in the oil layer to form precipitates, further blocking the oil layer and reducing the permeability of the reservoir, which greatly reduces the oil recovery effect.

[0022] Secondly, high sulfur content carbon dioxide poses a threat to the safe operation of oil recovery equipment. Sulfur may corrode equipment pipelines under high temperature and pressure, causing equipment damage and leakage. This not only increases the maintenance cost of equipment, but may also cause safety accidents and harm personnel and the environment.

[0023] From the perspective of environmental protection, the emission of high sulfur content carbon dioxide into the atmosphere will have a negative impact on air quality. Sulfur oxides are one of the main components of air pollutants, which may cause environmental problems such as acid rain and photochemical smog, posing a threat to ecosystems and human health.

[0024] Therefore, during the CO2 flooding process, the total sulfur content in CO2 needs to be strictly controlled. This can be achieved by adopting efficient desulfurization technology, optimizing the flooding process, and strengthening equipment maintenance. At the same time, environmental monitoring and pollution control should be strengthened to ensure that the impact of the flooding process on the environment is minimized. The total sulfur content in the CO2 used for flooding in oil fields is required to be no more than 0.1ppm.

[0025] In summary, the sulfur content in carbon dioxide has an important impact on the carbon dioxide oil recovery process, which requires sufficient attention and appropriate measures to be taken to control and manage it.

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Example 1

[0028] See also Figure 1 The method for improving the dry desulfurization removal efficiency in the carbon dioxide capture process shown in a preferred embodiment of the present application comprises the following steps: S1: Injecting raw gas: The raw gas and dry air are introduced into the system through the compressor.

[0029] S2: Pretreatment in the pre-desulfurization tower: After the raw gas and dry air enter the pre-desulfurization tower, the hydrogen sulfide in the raw gas undergoes an oxidation-reduction reaction with the desulfurizer in the pre-desulfurization tower, converting the hydrogen sulfide into elemental sulfur and water, preliminarily reducing the concentration of hydrogen sulfide in the raw gas to obtain a pretreated raw gas.

[0030] S3: Desulfurization treatment in hydrolysis tower: The pretreated raw gas obtained in step S2 is sequentially introduced into two hydrolysis towers, wherein the hydrolysis towers include a hydrolysis layer and a first adsorption layer. A hydrolysis catalyst is arranged in the hydrolysis layer. Carbonyl sulfide in the pretreated raw gas undergoes hydrolysis reaction in the hydrolysis layer and is converted into hydrogen sulfide. The first adsorption layer adsorbs and desulfurizes the generated hydrogen sulfide, and finally a desulfurized raw gas is obtained.

[0031] S4: adsorption treatment in a fine desulfurization tower: The desulfurized raw gas obtained in step S3 is introduced into a fine desulfurization tower, which includes two upper and lower second adsorption layers. The residual hydrogen sulfide and heavy metal and organic impurities in the desulfurized raw gas are removed for a second time through the desulfurization adsorption layers to obtain finished raw gas.

[0032] Among them, in steps S2-S4, the oxygen in the dry air oxidizes hydrogen sulfide into sulfur and sulfate that are more easily adsorbed, thereby improving the adsorption capture efficiency; at the same time, the oxygen in the dry air oxidizes carbonyl sulfide into hydrogen sulfide and sulfur dioxide that are easier to handle, thereby improving the desulfurization efficiency; In addition, the oxygen in the dry air further promotes the oxidation regeneration of the adsorption layer, thereby improving the utilization rate and adsorption efficiency of the adsorption layer.

[0033] Specifically, in this embodiment, the desulfurizer is ferric oxide, the hydrolysis catalyst is aluminum oxide, and the adsorption layer is activated carbon. Example 2

[0034] Based on Example 1, the applicant conducted multiple tests from June to July 2023 to test the effect of oxygen on desulfurization efficiency by changing the amount of dry air introduced. Figure 2 .

[0035] In this embodiment, the feed gas flow rate is 14000 Nm 3 / h, it can be seen that when the dry air supply is 20Nm 3 / h, affected by the residual sulfides in the equipment in the previous tests, although the desulfurization indicators in the first two times were poor, the total sulfur content in the finished raw gas was only 0.03ppm after stabilization, which is far lower than the standard of 0.1ppm. The desulfurization efficiency is greatly improved, and various sulfides in the raw gas can be effectively removed, which is a significant improvement compared with the existing technology.

[0036] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0037] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for improving dry desulfurization removal efficiency in a carbon dioxide capture process, characterized in that: The following steps are involved: S1: Injecting raw gas: introducing raw gas and dry air into the system through a compressor; S2: Pretreatment in pre-desulfurization tower: After the raw gas and dry air enter the pre-desulfurization tower, the hydrogen sulfide in the raw gas undergoes an oxidation-reduction reaction with the desulfurizer in the pre-desulfurization tower, converting the hydrogen sulfide into elemental sulfur and water, preliminarily reducing the concentration of hydrogen sulfide in the raw gas to obtain pretreated raw gas; S3: Desulfurization treatment in a hydrolysis tower: The pretreated raw gas obtained in step S2 is sequentially introduced into two hydrolysis towers, wherein the hydrolysis towers include a hydrolysis layer and a first adsorption layer, wherein a hydrolysis catalyst is arranged in the hydrolysis layer, and carbonyl sulfide in the pretreated raw gas undergoes hydrolysis reaction in the hydrolysis layer to be converted into hydrogen sulfide, and the first adsorption layer adsorbs and removes the generated hydrogen sulfide, and finally obtains a desulfurized raw gas; S4: adsorption treatment in a fine desulfurization tower: the desulfurized raw gas obtained in step S3 is passed into a fine desulfurization tower, which includes two upper and lower second adsorption layers. The residual hydrogen sulfide, heavy metals, and organic impurities in the desulfurized raw gas are removed through the desulfurization adsorption layers to obtain finished raw gas; Among them, in steps S2-S4, the oxygen in the dry air oxidizes hydrogen sulfide into more easily adsorbed sulfur and sulfate to improve the adsorption capture efficiency; at the same time, the oxygen in the dry air oxidizes carbonyl sulfide into more easily handled hydrogen sulfide and sulfur dioxide to improve the desulfurization efficiency.

2. The method for improving dry desulfurization removal efficiency in a carbon dioxide capture process according to claim 1, characterized in that: The first adsorption layer and the second adsorption layer include activated carbon.

3. The method for improving dry desulfurization removal efficiency in a carbon dioxide capture process according to claim 1, characterized in that: The desulfurizing agent is ferric oxide.

4. The method for improving dry desulfurization removal efficiency in a carbon dioxide capture process according to claim 1, characterized in that: The hydrolysis catalyst is aluminum oxide.

5. The method for improving dry desulfurization removal efficiency in a carbon dioxide capture process according to claim 1, characterized in that: The total sulfur content of the finished raw gas is less than 0.1 ppm.

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