Ammonium recovery method from acid gas genarated in cokes preparation

Abstract

A method for recovering ammonia using acid gas recovered during coke oven gas purification according to the present invention comprises: a step of separating elemental sulfur by reacting hydrogen sulfide among the acid gas recovered during coke oven gas purification with an iron-chelate catalyst; a step of regenerating the iron-chelate catalyst by supplying air to a reaction solution containing the iron-chelate catalyst remaining after the separation of the elemental sulfur; and a step of recovering ammonia from the regenerated reaction solution containing the iron-chelate catalyst.

Description

Technology Field

[0001] The present invention relates to a method for recovering ammonia using acid gas recovered during coke oven gas purification and a recovery apparatus. Background Technology

[0002] In order to use coke oven gas generated during the dry distillation of coal as a heat source for steel mills, an ammonia-containing absorbent solution called ansu is used to absorb and remove hydrogen sulfide (H2S), a major impurity contained in the coke oven gas.

[0003] Hydrogen sulfide in the coke oven gas is absorbed by the absorbent liquid, alum, to produce purified coke oven gas. The alum that has absorbed the hydrogen sulfide then undergoes a degassing process to remove the hydrogen sulfide, and is subsequently regenerated in a regeneration tower using steam or the like. During the process of regenerating the alum in the tower, the acid gas discharged from the top of the tower undergoes the Claus process, where catalytic oxidation occurs, converting the hydrogen sulfide contained in the acid gas into elemental sulfur.

[0004] The Klaus process for treating hydrogen sulfide in acid gas undergoes combustion and catalytic oxidation stages. In the combustion stage, hydrogen sulfide in the acid gas is combusted by oxygen in the air, and one-third of the hydrogen sulfide is converted into sulfur dioxide (SO2) (Equation (1)). Subsequently, the hydrogen sulfide and sulfur dioxide react to produce elemental sulfur (Equation (2)).

[0005] Equation (1): H2S +3 / 2O2→ SO2+ H2O

[0006] Equation (2): 2H2S + SO2 → 3 / 2S2 + 2H2O,

[0007] In the combustion reaction step described above, about 60 to 70 percent of the hydrogen sulfide in the acid gas is converted into elemental sulfur.

[0008] In addition, during the catalytic oxidation reaction step, hydrogen sulfide is converted into elemental sulfur using a catalyst such as activated alumina or titanium oxide (Equation (3)).

[0009] Equation (3): 2H2S + SO2→ 3 / 8S8+ 2H2O,

[0010] The conventional Claus process described above has the advantage of being able to produce elemental sulfur of over 99% high purity, but it has problems such as being complex, requiring high operating costs, and requiring very meticulous operating technology as it is operated at high temperatures.

[0011] In particular, if the acid gas introduced into the Claus process contains ammonia, the combustion temperature must be maintained at a temperature approximately 200°C higher than the combustion temperature of hydrogen sulfide, and there is a problem that the catalyst activity is reduced due to impurities contained in the acid gas, thereby reducing the catalyst lifespan. The problem to be solved

[0012] One aspect of the present invention for solving the aforementioned problem is to provide a method for recovering ammonia from coke oven gas and a recovery apparatus capable of stably converting hydrogen sulfide into elemental sulfur at room temperature from acid gas recovered as a byproduct in a coke oven gas purification process generated in a coke manufacturing process, while simultaneously efficiently recovering ammonia, which is a hydrogen carrier.

[0013] The technical problems intended to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below. means of solving the problem

[0014] To achieve the above objective, a method for recovering ammonia from coke oven gas according to one embodiment of the present invention may include: a step of separating elemental sulfur by reacting hydrogen sulfide with an iron-chelate catalyst among the acid gas recovered during coke oven gas purification; a step of regenerating the iron-chelate catalyst by supplying air to the reaction solution containing the iron-chelate catalyst remaining after the separation of the elemental sulfur; and a step of recovering ammonia from the regenerated reaction solution containing the iron-chelate catalyst.

[0015] The acid gas according to one embodiment of the present invention may include ammonia, carbon dioxide, hydrogen sulfide, hydrogen cyanide, and water.

[0016] According to one embodiment of the present invention, hydrogen sulfide and an iron-chelate catalyst in the acid gas may be included in a molar ratio of 1:2 to 1:3.

[0017] The iron-chelate catalyst according to one embodiment of the present invention may include one selected from Fe-ethylene diamine tetraacetic acid (EDTA), Fe-nitrilotriacetic acid (NTA), and mixtures thereof.

[0018] The separation of the elemental sulfur according to one embodiment of the present invention can be performed by reacting at a temperature of 50 to 80°C for 0.5 to 1 hour.

[0019] According to one embodiment of the present invention, the elemental sulfur can be separated with a recovery rate of 95% or more.

[0020] The ammonia recovery step according to one embodiment of the present invention can be performed by maintaining a temperature of 50 to 80°C.

[0021] According to one embodiment of the present invention, the ammonia can be separated with a recovery rate of 60% or more.

[0022] An ammonia recovery device for coke oven gas according to one embodiment of the present invention comprises: a hydrogen sulfide reaction unit that separates elemental sulfur by reacting hydrogen sulfide among acid gas recovered during coke oven gas purification with an iron-chelate catalyst and regenerates the iron-chelate catalyst contained in the reaction liquid remaining after the reaction; and an ammonia recovery unit connected to the hydrogen sulfide reaction unit and for recovering ammonia from the reaction liquid containing the regenerated iron-chelate catalyst transferred from the hydrogen sulfide reaction unit; wherein the hydrogen sulfide reaction unit may include an internal space filled with a structure in which a plurality of ring-shaped trays are stacked, an air inlet formed on one side, a catalyst inlet formed on the top, a reactant outlet formed on the bottom, and a catalyst-containing reaction liquid outlet.

[0023] According to one embodiment of the present invention, the plurality of ring-shaped trays may be formed with a total of 6 to 9 layers.

[0024] The hydrogen sulfide reaction unit according to one embodiment of the present invention can be maintained in an air atmosphere at a temperature of 50 to 80°C.

[0025] The ammonia recovery unit according to one embodiment of the present invention can be maintained at a temperature of 50 to 80°C. Effects of the invention

[0026] According to the present invention, a method for recovering ammonia from coke oven gas and a recovery apparatus can be provided, which can stably convert hydrogen sulfide into elemental sulfur at room temperature from acid gas recovered as a byproduct in a coke oven gas purification process generated in a coke manufacturing process, while simultaneously efficiently recovering ammonia, which is a hydrogen carrier.

[0027] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present invention belongs from the description below. Brief explanation of the drawing

[0028] FIG. 1 is a schematic diagram illustrating the configuration of a device for recovering ammonia from coke oven gas according to one embodiment of the present invention. Specific details for implementing the invention

[0029] Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those with average knowledge in the relevant technical field.

[0030] The terms used in this application are used merely to describe specific examples. For this reason, singular expressions include plural expressions unless the context clearly requires them to be singular. Additionally, it should be noted that terms such as “comprising” or “comprising” used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to preliminarily exclude the existence of other features, steps, functions, components, or combinations thereof.

[0031] Meanwhile, unless otherwise defined, all terms used in this specification shall be understood to have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Accordingly, unless explicitly defined in this specification, specific terms should not be interpreted in an overly ideal or formal sense. For instance, singular expressions in this specification include plural expressions unless the context clearly indicates an exception.

[0032] Additionally, terms such as "about," "substantially," etc., in this specification are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said sense, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content in which precise or absolute values ​​are mentioned to aid in understanding the invention.

[0033] A method for recovering ammonia from coke oven gas according to one embodiment of the present invention will be described in detail below.

[0034] A method for recovering ammonia from coke oven gas according to one embodiment of the present invention may include: a step of separating elemental sulfur by reacting hydrogen sulfide with an iron-chelate catalyst among acid gas recovered during coke oven gas purification; a step of regenerating the iron-chelate catalyst by supplying air to a reaction solution containing the iron-chelate catalyst remaining after the separation of elemental sulfur; and a step of recovering ammonia from the regenerated reaction solution containing the iron-chelate catalyst.

[0035] First, a step is performed to separate hydrogen sulfide by reacting the acid gas recovered during coke oven gas purification with an iron-chelate catalyst.

[0036] The acid gas recovered as a byproduct in the coke oven gas purification process generated in the coke manufacturing process contains ammonia, carbon dioxide, hydrogen sulfide, hydrogen cyanide, water, etc., and an iron-chelate (Fe-chelate) catalyst is added to react with the hydrogen sulfide in the acid gas in order to separate elemental sulfur from the acid gas.

[0037] The above iron-chelate catalyst is preferably a liquid iron-chelate catalyst and may include, for example, one selected from Fe-ethylenediaminetetraacetic acid (EDTA), Fe-nitrilotriacetic acid (NTA), and mixtures thereof, which are substances that accelerate ion velocity by coordinating with metal ions.

[0038] It is preferable to include hydrogen sulfide and an iron-chelate catalyst in the above acid gas in a molar ratio of 1:2 to 1:3. It is desirable to include hydrogen sulfide and an iron-chelate catalyst in the above molar ratio in the acid gas so as to increase the reactivity with hydrogen sulfide in the acid gas and thereby increase the separation efficiency of elemental sulfur.

[0039] The reaction between the acid gas and the iron-chelate catalyst can be carried out in an air atmosphere at a temperature of 50 to 80°C for 0.5 to 1 hour. If the reaction temperature is below 50°C, the selective reaction rate of hydrogen sulfide is low, resulting in a low hydrogen sulfide removal rate; if it exceeds 80°C, a reaction occurs not only with hydrogen sulfide but also with carbon dioxide contained in the acid gas, which may result in a low selective reaction rate of hydrogen sulfide. Additionally, if the reaction time is less than 0.5 hours, the contact time between hydrogen sulfide and the iron-chelate catalyst is low, resulting in a low selective reaction rate of hydrogen sulfide; and if it exceeds 1 hour, a reaction occurs not only with hydrogen sulfide but also with carbon dioxide contained in the acid gas, which may result in a low selective reaction rate of hydrogen sulfide.

[0040] Hydrogen sulfide in the acid gas is dissolved by the liquid iron-chelate catalyst, and the dissolved sulfur ions react with the iron-chelate catalyst to produce elemental sulfur. That is, the trivalent iron ions (Fe 3+ ) reacts with dissolved sulfur ions to form divalent iron ions (Fe 2+ It is converted into ) and as a result produces elemental sulfur (see reaction equation (1) below).

[0041] Reaction Equation (1): 2Fe 3+ -chelate + H2S → Sulfur + 2Fe 2+ -chelate

[0042] The solid elemental sulfur generated above is precipitated and discharged, and oxygen-containing air is supplied to the reaction solution containing the iron-chelate catalyst remaining after the separation of the elemental sulfur to regenerate the liquid iron-chelate catalyst (see reaction scheme (2) below).

[0043] Reaction Equation (2): O2 + 4Fe 2+ -chelate → 4Fe 3+ -chelate

[0044] As described above, the separated elemental sulfur can be separated with a recovery rate of 95% or more.

[0045] As described above, elemental sulfur is separated, and after regenerating the liquid iron-chelate catalyst contained in the reaction solution remaining after the reaction, a step of recovering ammonia from the regenerated iron-chelate catalyst-containing reaction solution is performed.

[0046] Specifically, the regenerated iron-chelate catalyst-containing reaction solution can be maintained at a temperature of 50 to 80°C to separate and recover ammonia, and the liquid iron-chelate catalyst from which ammonia has been separated can be used again as a catalyst raw material in the step of separating hydrogen sulfide from acid gas.

[0047] When separating ammonia as described above, if the temperature is below 50°C, the ammonia recovery rate from the reaction solution containing the regenerated iron-chelate catalyst in the liquid phase may be low, and if the temperature exceeds 80°C, impurities contained in the reaction solution containing the regenerated iron-chelate catalyst in the liquid phase may be separated together, making it difficult to separate only pure ammonia.

[0048] The ammonia separated as described above can be separated with a recovery rate of 60% or more, preferably 70% or more.

[0049] Next, an apparatus for recovering ammonia from coke oven gas according to another embodiment of the present invention will be described in detail with reference to the attached drawings.

[0050] FIG. 1 is a schematic diagram illustrating the configuration of a device for recovering ammonia from coke oven gas according to one embodiment of the present invention.

[0051] As illustrated in FIG. 1, an ammonia recovery device for coke oven gas according to one embodiment of the present invention comprises: a hydrogen sulfide reaction unit (10) that separates elemental sulfur by reacting hydrogen sulfide among acid gas recovered during coke oven gas purification with an iron-chelate catalyst and regenerates the iron-chelate catalyst contained in the reaction liquid remaining after the reaction; and an ammonia recovery unit (20) connected to the hydrogen sulfide reaction unit (10) and for recovering ammonia from the reaction liquid containing the regenerated iron-chelate catalyst transferred from the hydrogen sulfide reaction unit.

[0052] The above hydrogen sulfide reaction unit (10) includes an internal space (11) filled with a structure in which a plurality of ring-shaped trays (12) are stacked, an air inlet (13) formed on one side, a catalyst inlet (14) formed on the top, a reactant outlet (15) formed on the bottom, and a catalyst-containing reaction liquid outlet (16).

[0053] Acid gas recovered as a byproduct in the coke oven gas purification process generated in the coke manufacturing process is introduced into the internal space (11) of the hydrogen sulfide reaction unit (10), and when a liquid Fe-chelate catalyst is introduced from the upper catalyst inlet (14), the hydrogen sulfide in the acid gas reacts with the Fe-chelate catalyst as it passes through the ring-shaped tray (12) stacked in the internal space (11).

[0054] At this time, the contact surface area can be increased through the ring-shaped tray (11) stacked in the internal space (12) of the hydrogen sulfide reaction unit (10), thereby expanding the reaction area between hydrogen sulfide and the liquid iron-chelate catalyst, and the recovery rate of elemental sulfur can be maximized due to the improved reactivity resulting therefrom.

[0055] The above ring-shaped tray (12) can be formed in a total of 6 to 9 layers.

[0056] The internal space (11) of the above hydrogen sulfide reaction unit (10) can be maintained at an air atmosphere and a temperature of 50 to 80°C to react hydrogen sulfide in acid gas with a liquid iron-chelate catalyst.

[0057] The solid elemental sulfur produced by the reaction between the hydrogen sulfide in the above acid gas and the liquid iron-chelate catalyst is discharged through the reactant outlet (15) formed at the bottom of the hydrogen sulfide reaction unit (10) and stored in the elemental sulfur storage tank (17). The reaction solution containing the iron-chelate catalyst remaining after the reaction comes into contact with air introduced into the internal space (11) of the hydrogen sulfide reaction unit (10) through the air inlet (13) formed on one side of the hydrogen sulfide reaction unit (10), thereby regenerating the iron-chelate catalyst contained in the reaction solution.

[0058] The above-mentioned reaction solution containing the regenerated iron-chelate catalyst is discharged through the catalyst outlet (16) at the bottom of the hydrogen sulfide reaction unit (10) and transferred to the internal space of the ammonia recovery unit (20).

[0059] The reaction solution containing the regenerated iron-chelate catalyst introduced into the ammonia recovery unit (20) is maintained in the ammonia recovery unit (20) where the internal space temperature is maintained at 50 to 80°C, and the ammonia is separated, and the separated ammonia is discharged through the ammonia outlet (21) formed at the top of the ammonia recovery unit (20). The iron-chelate catalyst from which the ammonia has been separated is discharged through the catalyst outlet (22) formed at the bottom of the ammonia recovery unit (20), and the discharged iron-chelate catalyst is then introduced back into the hydrogen sulfide reaction unit (10) to participate in the reaction for the separation of elemental sulfur.

[0060] The present invention will be explained in more detail below through the following examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

[0061] Examples 1–4 and Comparative Examples 1–2

[0062] As shown in Table 1 below, the molar amount of Fe-EDTA, an iron-chelate catalyst, was varied relative to the molar amount of hydrogen sulfide contained in the acid gas and supplied to the hydrogen sulfide reaction section to react the hydrogen sulfide with the liquid iron-chelate catalyst. Additionally, air was supplied through an air inlet formed on one side of the hydrogen sulfide reaction section to convert the hydrogen sulfide reacted with the iron-chelate catalyst into solid elemental sulfur, and the elemental sulfur was discharged through a reactant outlet formed at the bottom. Subsequently, the liquid iron-chelate catalyst, regenerated by the injected air, was discharged through the catalyst outlet of the hydrogen sulfide reactor and transferred to the ammonia recovery section, where ammonia was recovered while maintaining the internal temperature of the ammonia recovery section at 50–80°C.

[0063] The recovery rates of elemental sulfur and ammonia separated in Examples 1 to 4 and Comparative Examples 1 to 2 were measured, and the results are shown in Table 1 below.

[0064] The elemental sulfur recovery rate was expressed as the ratio of separated elemental sulfur to the moles of hydrogen sulfide introduced into the hydrogen sulfide reaction unit, and the ammonia recovery rate was expressed as the ratio of separated ammonia to the reaction solution containing the regenerated iron-chelate catalyst introduced into the ammonia recovery unit.

[0065] division Hydrogen sulfide (moles) Fe-EDTA (mol) Ammonia reaction section temperature (°C) Elemental Sulfur Recovery Rate (%) Ammonia recovery rate (%) Example 1 1 2 80 95 80 Example 2 1 3 80 99 80 Example 3 1 2 50 95 60 Example 4 1 3 50 99 80 Comparative Example 1 1 1 50 65 30 Comparative Example 2 1 1 80 65 50

[0066] As shown in Table 1 above, in the case of Examples 1 to 4, in which hydrogen sulfide contained in the acid gas and an iron-chelate catalyst were mixed and reacted in a molar ratio of 1:2 to 1:3 according to the present invention, it was confirmed that the proportion of elemental sulfur recovered from hydrogen sulfide in the acid gas was higher compared to Comparative Examples 1 and 2. In addition, it was confirmed that Examples 1 to 4, in which the reaction solution containing the regenerated iron-chelate catalyst was maintained at 50 to 80°C, also showed excellent ammonia recovery rates. Although the embodiments of the invention disclosed above have been illustrated and described, the disclosed invention is not limited to the specific embodiments described above, and various modifications may be made by those skilled in the art to which the disclosed invention belongs without departing from the gist of the claims. Explanation of the symbols

[0067] 10: Hydrogen sulfide reaction section 12: Ring-shaped tray 20: Ammonia recovery unit

Claims

Claim 1 A method for recovering ammonia from coke oven gas, comprising: a step of separating elemental sulfur by reacting hydrogen sulfide with an iron-chelate catalyst in acid gas recovered during coke oven gas purification; a step of regenerating the iron-chelate catalyst by supplying air to a reaction solution containing the iron-chelate catalyst remaining after the separation of elemental sulfur; and a step of recovering ammonia from the regenerated reaction solution containing the iron-chelate catalyst. Claim 2 A method for recovering ammonia from coke oven gas according to claim 1, wherein the acid gas comprises ammonia, carbon dioxide, hydrogen sulfide, hydrogen cyanide, and moisture. Claim 3 A method for recovering ammonia from coke oven gas according to claim 1, wherein hydrogen sulfide and an iron-chelate catalyst in the acid gas are included in a molar ratio of 1:2 to 1:

3. Claim 4 A method for recovering ammonia from coke oven gas according to claim 1, wherein the iron-chelate catalyst comprises one selected from Fe-ethylenediamine tetraacetic acid (EDTA), Fe-nitrilotriacetic acid (NTA), and mixtures thereof. Claim 5 A method for recovering ammonia from coke oven gas according to claim 1, wherein the separation of the elemental sulfur is performed by reacting at a temperature of 50 to 80°C for 0.5 to 1 hour. Claim 6 A method for recovering ammonia from coke oven gas in which the elemental sulfur is separated with a recovery rate of 95% or more, according to claim 1. Claim 7 A method for recovering ammonia from coke oven gas according to claim 1, wherein the ammonia recovery step is performed by maintaining the ammonia recovery step at a temperature of 50 to 80°C. Claim 8 A method for recovering ammonia from coke oven gas in which the ammonia is separated with a recovery rate of 60% or more, in accordance with claim 1. Claim 9 A coke oven gas ammonia recovery device comprising: a hydrogen sulfide reaction unit for separating elemental sulfur by reacting hydrogen sulfide among acid gases recovered during coke oven gas purification with an iron-chelate catalyst and regenerating the iron-chelate catalyst contained in the reaction liquid remaining after the reaction; and an ammonia recovery unit connected to the hydrogen sulfide reaction unit and for recovering ammonia from the reaction liquid containing the regenerated iron-chelate catalyst transferred from the hydrogen sulfide reaction unit; wherein the hydrogen sulfide reaction unit comprises an internal space filled with a structure in which a plurality of ring-shaped trays are stacked, an air inlet formed on one side, a catalyst inlet formed on the top, a reactant outlet formed on the bottom, and a catalyst-containing reaction liquid outlet. Claim 10 In claim 9, the ammonia recovery device for coke oven gas, wherein the plurality of ring-shaped trays are formed in a total of 6 to 9 layers. Claim 11 In claim 9, the hydrogen sulfide reaction unit is an ammonia recovery device for coke oven gas maintained in an air atmosphere at a temperature of 50 to 80°C. Claim 12 In claim 9, the ammonia recovery unit is an ammonia recovery device for coke oven gas maintained at a temperature of 50 to 80°C.

Images