KR20200072373A - manufacturing method of liquid catalyst compositions for desulfurization and pre-treatment apparatus of bio gas - Google Patents

Abstract

The present invention relates to a method for preparing a liquid catalyst for desulfurization which provides biogas with a high added value, and a biogas pretreatment apparatus using the same. Particularly, the method can increase the concentration of a chelating agent contained in the liquid catalyst and can prevent blocking of a spraying nozzle. The method for preparing a liquid catalyst for desulfurization includes the steps of: dissolving an iron salt in water to obtain an aqueous iron solution; dissolving a pH modifier selected from sodium hydrogen carbonate and sodium carbonate in water to obtain a pH modifier solution; adding a chelating agent selected from EDTA, NTA and HIDS to the pH modifier solution to obtain a chelating agent solution; mixing the iron solution with the chelating agent solution to obtain a mixed solution; and adding a stabilizer to the mixed solution.

Description

A manufacturing method of a liquid catalyst for desulfurization and a biogas pretreatment device using the same

The present invention relates to a method for preparing a liquid catalyst for desulfurization for high added value of biogas and a biogas pre-treatment device using the same, more specifically, to increase the concentration of the chelating agent contained in the liquid catalyst and to prevent clogging of the spray nozzle. The present invention relates to a method for preparing a liquid catalyst for desulfurization and a biogas pretreatment device using the same.

As the industry is advanced and human life is enriched, the problem of treatment of high-concentration organic waste such as livestock manure and food waste is emerging seriously, and for this treatment, it is securing energy sources through anaerobic fermentation.

Methane gas production technology by anaerobic fermentation has already been settled and distributed in Europe, Japan, etc., as well as environmental functions such as treatment of high-concentration organic wastes (cattle manure, food waste, agricultural by-products, etc.), as well as alternative energy production such as biogas It is a technology that can simultaneously achieve the natural cyclic function through the function and reduction of fermented organic waste through farmland.

Biogas is a great source of energy because of its high methane content. Therefore, biogas can be used in any demanding place where natural gas is used only after an appropriate level of reforming. For example, biogas can be used as fuel for heating, heating, and power generation, or used as city gas or vehicle fuel through refining.

However, hydrogen sulfide (H ₂ S) is contained in biogas generated through anaerobic fermentation. When the human body is exposed to hydrogen sulfide, it not only has a fatal effect on life, but is also converted into sulfur dioxide and sulfuric acid in the process of biogas utilization such as cogeneration, which adversely affects facilities such as corrosion of boilers, engine cylinders, and exhaust pipes. .

Therefore, a method using a liquid catalyst is known as a method for removing hydrogen sulfide in biogas.

The liquid phase oxidation process, in which biogas is brought into contact with a liquid catalyst to react in a liquid phase, removes gas components using gas solubility and a redox reaction of the catalyst, and the catalyst is regenerated and circulated to generate waste water. It does not have the advantage of being able to use the absorption tower used to remove the existing odor, and the installation cost is low.

Since hydrogen sulfide dissolved in a liquid catalyst is separated into solid sulfur by oxygen, a metal catalyst is usually used to promote oxidation, and these metal ions used must have affinity and a redox mechanism. Examples of the metal ion include Fe ^{2 +} , Fe ³⁺ , V ⁴⁺ , V ⁵⁺ , Cu ^{2 +} , Cu ^{3 +} , As ^{2 +} , and As ^{3 +} . These metal ions oxidize sulfur ions in aqueous solution and reduce themselves, and catalyze the oxidation-reduction reaction that oxidizes again with oxygen.

Particularly, iron chelate using ferrous metal as a liquid catalyst can be operated at room temperature and normal pressure by using the solubility of sulfide gas in water and the oxidation-reduction principle of the iron chelate compound, without wastewater and secondary pollution, and operating and equipment costs. It is inexpensive and has recently been applied in various industries. As a chelating agent that forms a complex with iron to perform a sulfide removal reaction, NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid), and HIDS (hydroxyiminodisuccinic acid) are well known.

However, as disclosed in Korean Patent Publication No. 10-2014-0001723, the conventional liquid catalyst directly adds a chelating agent to the solution in which the iron salt is dissolved, so that the molar ratio of the iron ion:chelating agent is 1:0.5 to 2.5, There is a problem that the concentration of the above chelating agent cannot be increased. The higher the concentration of the chelating agent, the faster the regeneration rate of the catalyst and has the advantage of removing hydrogen sulfide in a smaller amount. Despite this, there is a limitation that the molar ratio of the iron ion:chelating agent cannot be increased to 1:2.5 or more using the conventional technique.

On the other hand, as disclosed in Korean Patent Registration No. 10-0766125, in order to remove hydrogen sulfide using a liquid catalyst, polling is usually installed in multiple stages inside the scrubber, but solid sulfur mixed with the liquid catalyst is often attached to the polling surface. There is difficulty in maintenance due to blockage. In addition, when the liquid catalyst is injected into the scrubber through the nozzle, there is a problem in that the solid sulfur mixed in the liquid catalyst clogs the nozzle.

1. Republic of Korea Patent Publication No. 10-2014-0001723: Desulfurization liquid catalyst composition and method for manufacturing the same 2. Republic of Korea Patent No. 10-0766125: Hydrogen sulfide removal device using liquid catalyst

The present invention was created to improve the above problems, and by developing a manufacturing method capable of increasing the concentration of the chelating agent contained in the liquid catalyst, the regeneration rate of the liquid catalyst is fast and the removal efficiency of hydrogen sulfide can be increased even with a smaller amount. The purpose of the present invention is to provide a method for preparing a liquid catalyst for desulfurization.

In addition, the present invention is to provide a biogas pre-treatment device that can prevent the phenomenon of nozzle clogging due to the solid sulfur mixed in the liquid catalyst and at the same time increase the contact efficiency of the liquid catalyst and the biogas to eliminate the need for polling. There is a purpose.

A method of preparing a liquid catalyst for desulfurization of the present invention for achieving the above object comprises dissolving an iron salt in water to obtain an iron solution; Dissolving a pH adjusting agent selected from sodium hydrogen carbonate and sodium carbonate in water to obtain a pH adjusting agent solution; Adding a chelating agent selected from EDTA, NTA, and HIDS to the pH adjusting agent solution to obtain a chelating agent solution; Mixing the iron solution and the chelating agent solution to obtain a mixed solution; And adding a stabilizer to the mixed solution.

When mixing the iron solution and the chelating agent solution, iron ions: chelating agent are mixed in a molar ratio of 1:3-4.

Oxygen or air is injected into the mixed solution to induce a pH increase.

And the biogas pre-treatment device of the present invention for achieving the above object is a cleaning tower for the biogas inlet and outlet; A spray tube installed inside the washing tower and having a plurality of nozzles for spraying a liquid catalyst; A catalyst collection tank installed at a lower portion of the washing tower to collect a liquid catalyst sprayed through the nozzle; A catalyst supply unit connected to an inlet of the injection pipe to supply a liquid catalyst to the injection pipe; And a nozzle clogging prevention pipe connected to an outlet of the injection pipe and extending into the catalyst collection tank to prevent the nozzle from being clogged by solid sulfur in the liquid catalyst flowing into the injection pipe.

It is connected to the catalyst supply unit further comprises a rotating injection means for spraying while rotating the liquid catalyst into the interior of the washing tower.

It further includes a turbulent means for turbulent biogas to increase the contact efficiency of the liquid catalyst and the biogas moving inside the washing tower.

The turbulence means is formed to protrude from the inner circumferential surface of the washing tower, but has a plurality of turbulence inducers formed to be curved into a curved surface.

As described above, in the present invention, unlike the conventional method of adding the chelating agent directly to the iron solution in which the iron salt is dissolved, the iron ion:chelating agent is prepared through a method of mixing the chelating agent with the iron solution in a state in which the chelating agent is dissolved in the pH control agent solution. The molar ratio can be greatly increased to 1:3 or more.

Accordingly, the present invention has the advantage that the regeneration rate of the liquid catalyst is fast and the removal efficiency of hydrogen sulfide is increased even in a smaller amount.

In addition, the present invention can improve the clogging phenomenon of the nozzle due to the solid sulfur by connecting the injection pipe with a nozzle for spraying a liquid catalyst into the interior of the washing tower with a catalyst collection tank through a separate pipe.

In addition, the present invention can solve the problem caused by polling while increasing the contact efficiency of the liquid catalyst and biogas by installing a turbulent induction target inside the washing tower instead of polling that is frequently blocked by solid sulfur.

1 is a block diagram showing a method of manufacturing a liquid catalyst for desulfurization according to an example of the present invention,
Figure 2 is a schematic view showing a biogas pre-treatment device according to an embodiment of the present invention,
3 is a cross-sectional view excerpting the main part of FIG. 2,
Figure 4 is a photograph showing the state of the liquid catalyst prepared by a conventional method,
5 is a photograph showing the state of the liquid catalyst prepared according to the present invention,
Figure 6 is a graph showing the results of the pH change over time of the five types of liquid catalyst while injecting air into the liquid catalyst,
7 is a graph showing the results of hydrogen sulfide removal experiments for five types of liquid catalysts,
Figure 8 is a photograph showing the state of the two-stage pilot plant produced for field testing,
9 is a graph showing hydrogen sulfide removal and pH change of a liquid catalyst using the pilot plant of FIG. 8.

Hereinafter, a method for preparing a liquid catalyst for desulfurization according to a preferred embodiment of the present invention and a biogas pretreatment device using the same will be described in detail.

In the present invention, the liquid catalyst uses iron as a catalyst metal. Iron (Fe) oxidizes sulfur in an aqueous solution and reduces itself, and catalyzes by an oxidation-reduction reaction that oxidizes again with oxygen. This iron has the advantage of being non-toxic and harmless to the environment.

The liquid catalyst for desulfurization of the present invention includes an iron salt dissolved in water to generate iron (Fe) ions, and a chelating agent that binds with the iron ions.

If it is a substance that can be dissolved in water as an iron salt to form iron ions, there is no limitation on the type. For example, Fe(NO ₃ ) ₃ , FeCl, FeSO ₄ as iron salt Any one selected from among them can be used.

As a chelating agent, any one selected from nitrotriacetate (NTA), ethylenediaminetetraacetate (EDTA), and hydroxyiminodisuccinic acid (HIDS) can be used.

These chelating agents form stable iron chelate compounds (Fe-EDTA, Fe-NTA, Fe-HIDS) with iron ions.

The liquid catalyst is preferably an iron ion: chelating agent in a molar ratio of 1:3-4.

The liquid catalyst may further include any one of pH regulators selected from sodium hydrogen carbonate and sodium carbonate, and any one stabilizer selected from sodium thiosulfate and ammonium thiosulfate.

The pH adjusting agent is any one selected from sodium hydrogen carbonate (NaHCO ₃ ) and sodium carbonate (Na ₂ CO ₃ ). The stability of the complex formation of iron ions and chelating agents is related to the pH of the solution.

Stabilizers reduce the production of OH radicals to maintain catalyst stability. In the hydrogen sulfide removal reaction using an iron-chelating catalyst, the stability of the catalyst may decrease as the reaction time progresses. This is because the conversion of Fe(II)-chelate to Fe(III)-chelate is slow, increasing the precipitation amount of iron in the catalyst, so the catalyst concentration is rapidly lowered and the stability of the catalyst due to the hydrogen sulfide removal reaction is reduced.

As a stabilizer, any one selected from sodium thiosulfate (Na ₂ S ₂ O ₃ ) and ammonium thiosulfate ((NH ₄ ) ₂ S ₂ O ₃ ) can be applied.

Hereinafter, a method of manufacturing the above-described liquid catalyst for desulfurization will be described step by step with reference to FIG. 1.

1. Iron solution obtaining step

First, an iron salt is dissolved in water to obtain an iron solution. The pH of the iron solution may be 1 to 1.5.

Fe(NO ₃ ) ₃ , FeCl, FeSO ₄ as iron salt Any one selected from among them can be used. Iron salts dissolve in water to form iron ions. The ratio of iron salt and water can be adjusted so that the concentration of iron ions in the iron solution is 1000 to 5000 ppm.

2. pH adjusting agent solution obtaining step

Next, the pH adjusting agent is dissolved in water to obtain a pH adjusting agent solution. The ratio of the pH adjusting agent to the water can be adjusted so that the pH of the pH adjusting solution becomes 7-8.

As the pH adjusting agent, any one selected from sodium hydrogen carbonate (NaHCO ₃ ) and sodium carbonate (Na ₂ CO ₃ ) can be used.

3. Obtaining a chelating agent solution

Next, a chelating agent is added to the pH adjusting agent solution to obtain a chelating agent solution.

As a chelating agent, any one selected from nitrotriacetate (NTA), ethylenediaminetetraacetate (EDTA), and hydroxyiminodisuccinic acid (HIDS) can be used.

4. Step of obtaining mixed solution

Next, an iron solution and a chelating agent solution are mixed to obtain a mixed solution. At this time, the iron solution and the chelating agent solution are mixed so that the iron ion: chelating agent becomes 1:3 to 4 in a molar ratio.

When the chelating agent is directly added to the iron solution, the concentration of the chelating agent cannot be increased, but the present invention is mixed with the iron solution in a state in which the chelating agent is dissolved in the pH control agent solution, so the molar ratio of the iron ion:chelating agent is 1:3 or more. Can be greatly increased.

Meanwhile, after obtaining the mixed solution, pure oxygen or air may be injected into the mixed solution to induce a gradual increase in pH of the mixed solution. The injection of oxygen or air also has the effect of improving the binding stability of iron ions and chelating agents.

When oxygen or air is injected into the mixed solution, it is preferable to inject oxygen or air by aeration. Since this aeration method forms a fast flow in the mixed solution, it has the effect of stirring the mixed solution to promote the reaction.

In addition, a pH adjusting agent may be added to the mixed solution together with the injection of oxygen or air into the mixed solution. As the pH adjusting agent, any one selected from sodium hydrogen carbonate (NaHCO ₃ ) and sodium carbonate (Na ₂ CO ₃ ) may be used.

In this way, the final pH of the mixed solution is adjusted to 8-9.

5. Stabilizer Addition Step

Next, a stabilizer is added to the mixed solution to obtain a stable high concentration liquid catalyst for desulfurization. The stabilizer can be added at 1-20% (v/v).

As the stabilizer, any one selected from sodium thiosulfate (Na ₂ S ₂ O ₃ ) and ammonium thiosulfate ((NH ₄ ) ₂ S ₂ O ₃ ) can be used.

It is difficult for the conventional liquid catalyst to increase the maximum molar ratio of iron ions:chelate to 1:2.5 or more. However, the present invention can improve the manufacturing process as described above to increase the molar ratio of iron ions:chelating agent to 1:3-4.

When the liquid catalyst is prepared by the conventional method, when the molar ratio of the iron ion:chelating agent is 1:4, a large amount of solid precipitate is generated as shown in FIG. 4, and the chelating agent that is not melted is present in a large amount. However, the liquid catalyst prepared according to the present invention as shown in FIG. 5 does not generate solid precipitate at all because the chelating agent is completely dissolved even if the molar ratio of the iron ion:chelating agent is 1:4.

Hereinafter, a biogas pre-treatment device using the above-described liquid catalyst for desulfurization will be described.

Among the biogas generated through anaerobic fermentation, hydrogen sulfide (H ₂ S) is contained. When the human body is exposed to hydrogen sulfide, it not only has a fatal effect on life, but is also converted into sulfur dioxide and sulfuric acid in the process of biogas utilization such as cogeneration, which adversely affects facilities such as corrosion of boilers, engine cylinders, and exhaust pipes. .

Therefore, hydrogen sulfide in the biogas is removed through the biogas pretreatment device of the present invention.

2 and 3, the biogas pre-treatment apparatus according to an embodiment of the present invention is a washing tower (10,30,50) and the inside of the washing tower (10,30,50) in which biogas is introduced and discharged It is installed on the injection nozzles (20,40,60) are installed a plurality of nozzles (21,41,61) for spraying a liquid catalyst, and installed in the lower portion of the washing tower (10,30,50) nozzles (21, 41,61) is connected to the inlet of the catalyst collection tank (60) and the injection pipe (20,40,60) where the liquid catalyst injected through the injection pipe (20,40,60) to supply the liquid catalyst It is provided with a catalyst supply unit 70 for, and a nozzle clogging prevention pipe (23,43,63) connected to the outlet of the injection pipe (20,40,60) and extending into the inside of the catalyst collection tank (60).

The washing towers 10, 30 and 50 may be installed only one or two or more may be connected in multiple stages. In the illustrated example, three washing towers 10, 30 and 50 have a structure connected in series. For convenience of explanation, the first washing tower 10, the second washing tower 30, and the third washing tower 30 will be described separately from the front end.

The first to third washing towers 10, 30, and 50 are formed with an inlet through which biogas is introduced and an outlet through which biogas is discharged.

In the first washing tower 10, the inlet 11 is formed at the top, and the outlet 13 is formed at the bottom. In addition, the second washing tower 30 and the third washing tower 50 have inlets 31 and 51 formed at the bottom, and outlets 33 and 53 at the top.

The biogas flowing into the upper portion of the first washing tower 10 passes through the inside of the first washing tower 10 while forming a downstream flow and is discharged to the lower portion of the first washing tower 10. And the biogas discharged to the lower portion of the first washing tower 10 flows into the lower portion of the second washing tower 30 through the first connecting pipe (3). The biogas flowing into the lower portion of the second washing tower 30 passes through the interior of the second washing tower 30 while forming an upward flow and is discharged to the upper portion of the second washing tower 30. In addition, biogas discharged to the upper portion of the second washing tower 30 flows into the lower portion of the third washing tower 50 through the second connecting pipe 5. The biogas flowing into the lower portion of the third washing tower 50 passes through the inside of the third washing tower 50 while forming an upward flow and is discharged to the upper portion of the third washing tower 50.

The gas inlet pipe 1 is connected to the inlet 11 of the first washing tower 10 and biogas is introduced into the first washing tower 10. A plurality of windows 15 may be provided on the side surface of the first washing tower 10 so as to look inside.

The injection pipe 20 is installed inside the first washing tower 10. One or two or more injection pipes 20 may be installed at regular intervals. In the first washing tower 10, three injection pipes 20 are spaced vertically and installed.

A plurality of nozzles 21 are installed in the injection pipe 20. The liquid catalyst introduced into the injection pipe 20 is injected into the interior of the first washing tower 10 through the nozzle 21 to contact the biogas flowing into the first washing tower 10.

The biogas discharged from the first washing tower 10 flows into the second washing tower 30 through the first connecting pipe 3.

The second washing tower 30 has the same structure as the first washing tower 10 as well as different positions of the inlet and outlet. In the second washing tower 30, three injection pipes 40 are spaced vertically and installed. A plurality of nozzles 41 are installed in each injection pipe 40.

The biogas discharged from the second washing tower 20 flows into the third washing tower 50 through the second connecting pipe 5.

In the third washing tower 50, two injection pipes 60 are spaced vertically and installed. A plurality of nozzles 61 are installed in each injection pipe 60. In addition, a demister 55 for removing moisture in the biogas may be installed inside the third washing tower 50. The demister 55 is installed inside the third washing tower 50.

The catalyst collection tank 60 is installed under the washing towers 10, 30 and 50. The interior space of the washing tower (10, 30, 50) is in communication with the catalyst collection tank (60). Therefore, the liquid catalyst sprayed into the washing towers 10, 30 and 50 falls downward and collects in the catalyst collection tank 60.

A catalyst regeneration means 80 may be provided to regenerate the liquid catalyst of the catalyst collection tank 60. As the catalyst regeneration means 80, a blower 81, an air pipe 83 installed inside the catalyst collection tank 60, and an air supply pipe 85 connecting the blower 81 and the air pipe 83 are provided. To be equipped.

The catalyst supply unit 70 is connected to the injection pipe inlets of each of the washing towers 10, 30 and 50 to supply a liquid catalyst to the injection pipes 20, 40 and 60.

To this end, the catalyst supply unit 70 includes a catalyst storage tank (not shown) in which the liquid catalyst is stored, a pump 71 installed in the catalyst storage tank to transport the liquid catalyst, a pump 71 and injection pipes 20 and 40, It consists of a catalyst supply pipe (73) connecting 60).

And unlike shown, a pump 71 is installed in the catalyst collection tank 60 to allow the liquid catalyst of the catalyst collection tank 60 to flow into the injection pipes 20, 40, 60 through the catalyst supply pipe 73. .

The nozzle clogging prevention pipes 23, 43, and 63 are connected to the outlets of the injection pipes 21, 41, 61 and extend into the inside of the catalyst collection tank 60.

Since the outlets of the injection pipes (21,41,61) are connected to the nozzle clogging prevention pipes (23,43,63), some of the liquid catalysts introduced into the injection pipes (21,41,61) are cleaned through each nozzle. It is injected into the inside, and a part passes through the nozzle blockage prevention pipes (21, 41, 61) and flows into the catalyst collection tank. The nozzle clogging phenomenon caused by solid sulfur particles can be minimized by the flow of the liquid catalyst flowing directly toward the nozzle clogging prevention pipes 21, 41 and 61.

On the other hand, in the present invention, unlike the prior art, polling is not installed inside the washing tower. Conventionally, one or more polling layers were installed inside the washing tower to increase the gas-liquid contact efficiency, but frequent clogging and maintenance difficulties occurred due to the deposition of solid sulfur. In the present invention, the polling layer is omitted so that polling is not blocked. However, if the polling is not installed, the contact efficiency between the biogas and the liquid catalyst decreases. In order to solve this problem, the present invention is provided with a rotating injection means for spraying a liquid catalyst while rotating inside the washing tower instead of the polling layer to improve the desulfurization efficiency.

The rotary injection means is a branch pipe (25,45,65) branched from the catalyst supply pipe (73), and a rotary nozzle (27,47,67) connected to the branch pipe (25,45,65) and installed inside the washing tower ). The rotary nozzle is a nozzle that sprays while rotating 360 degrees, and a structure such as a conventional rotary spring cooler can be applied.

The liquid catalyst is sprayed while rotating in the interior of the washing tower by the rotating injection means, thereby improving the contact efficiency with the liquid catalyst.

On the other hand, the present invention further comprises a turbulent means to further improve the contact efficiency of the liquid catalyst and biogas.

The turbulence means is formed to protrude from the inner circumferential surface of the washing tower, but is provided with a plurality of turbulent induction targets 90 formed to be curved into a curved surface. FIG. 3 shows a turbulent flow guide 90 installed inside the first washing tower 10. Although not shown, turbulence inducing flags are installed inside the second and third washing towers.

Turbulent flow guides are installed at regular intervals on the inner circumferential surface of the washing tower at 90-degree intervals. Turbulent induction feathers are formed to bend in a specific direction. In the illustrated example, the four turbulent inducers are bent counterclockwise. Such turbulent inducers have turbulent flow of biogas moving inside the washing tower to greatly increase the contact efficiency of the liquid catalyst.

Hereinafter, a method for preparing the liquid catalyst of the present invention through an example of an experiment will be described. However, the following experimental examples are intended to specifically describe the present invention, and the scope of the present invention is not limited to the following experimental examples.

<Preparation of liquid catalyst>

Iron nitrate (Fe(NO ₃ ) _{3 in} 0.5L of distilled water ₃ ㆍ9H ₂ O) 36.16 g was dissolved to obtain an iron solution. The iron concentration in the iron solution was fixed at 5000 ppm.

Then, sodium carbonate was dissolved in 0.5 L of distilled water to obtain a pH adjuster solution having a pH of 8. Then, 150 g of ethylenediaminetetraacetate (hereinafter, EDTA) was added as a chelating agent to 0.5 L of the pH adjusting agent solution to obtain a chelating agent solution.

Next, an iron solution and a chelating agent solution were mixed to obtain a mixed solution. At this time, the mixing ratio of the iron solution and the chelating agent solution was adjusted so that the iron ion: chelating agent became 1:2 to 4 in molar ratio.

And to adjust the pH of the mixed solution, sodium carbonate was added to 1 L of the mixed solution to adjust the pH of the mixed solution to 8, and 100 ml of sodium thiosulfate (Na ₂ S ₂ O ₃ ) was added as a stabilizer to prepare a liquid catalyst.

A total of 5 liquid catalysts were tested according to the molar ratio of iron ions: chelating agent.

<Oxygen reaction experiment>

While injecting air into 1 L of the liquid catalyst at a rate of 1 L/min for 60 minutes, the change in pH over time of the five types of liquid catalyst was observed. The experimental results are shown in FIG. 6.

Referring to FIG. 6, it was found that the higher the concentration of the chelating agent when the same amount of air was injected, the higher the pH increase rate. The higher the pH increase rate, the better the stability of the liquid catalyst and the performance of the liquid catalyst. Therefore, it was confirmed that the liquid catalyst having a molar ratio of 1:4 had the highest pH increase rate and was excellent as a liquid catalyst.

<Hydrogen sulfide removal experiment>

Hydrogen sulfide removal experiments were performed by contacting five types of liquid catalyst with a gas containing hydrogen sulfide.

After filling each liquid catalyst into the reactor, the concentration of hydrogen sulfide detected at the top of the reactor was measured by time by injecting 10,000 ppm of hydrogen sulfide gas into the bottom of the reactor at a rate of 1 L/min using a mass flow controller (MFC). The experimental results are shown in FIG. 7.

Referring to FIG. 7, hydrogen sulfide was not detected in all liquid catalysts for about 20 minutes from the start of the experiment. However, the concentration of hydrogen sulfide was gradually increased after 25 minutes in the liquid catalysts having a molar ratio of 1:2, 1:2.5, and 1:3. In addition, the liquid catalyst having a molar ratio of 1:3.5 showed an increasing trend after 45 minutes, but the hydrogen catalyst was not detected in the liquid catalyst having a molar ratio of 1:4 for 60 minutes.

Therefore, it was found that the hydrogen sulfide removal efficiency increased as the molar ratio increased.

<On-site verification experiment>

Experiments were conducted at the site of an anaerobic methane fermentation tank installed in Changnyeong, Gyeongnam, using a liquid catalyst having the best molar ratio of 1:4. For the field test, a pilot plant composed of two stages was designed and manufactured as shown in FIG. 8. The experimental conditions are shown in Table 1 below.

division Condition Influent gas component H ₂ S: 1,800~2,000ppm,
NH ₃ : 200ppm
CH ₄ : 55~60% Inlet gas temperature 35~45℃ Influent gas flow rate 3m ³ /min Liquid catalyst input 260L (circulation tank, regeneration tank) Additional equipment Ring blower, metering pump, air pump, circulation pump, filter press Measuring equipment pH meter, H ₂ S detection tube (4L, 4H, 4HH)
Tetra Pack (2L, 4L) Inspection items H ₂ S, pH,

The experimental results are shown in FIG. 9.

Referring to FIG. 9, the removal rate of hydrogen sulfide was 99.9% or more during the test period, and the pH change rate was also stably changed.

Above, the present invention has been described with reference to one embodiment, but this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible therefrom. Therefore, the true protection scope of the present invention should be defined only by the appended claims.

10: first washing tower 20: spray tube
21: nozzle 30: second washing tower
50: third washing tower 60: catalyst collection tank
70: catalyst supply

Claims (7)

Dissolving iron salt in water to obtain an iron solution;
Dissolving a pH adjusting agent selected from sodium hydrogen carbonate and sodium carbonate in water to obtain a pH adjusting agent solution;
Adding a chelating agent selected from EDTA, NTA, and HIDS to the pH adjusting agent solution to obtain a chelating agent solution;
Mixing the iron solution and the chelating agent solution to obtain a mixed solution;
The step of adding a stabilizer to the liquid catalyst; Method for producing a liquid catalyst for desulfurization comprising a. The method of claim 1, wherein when mixing the iron solution and the chelating agent solution, a method of preparing a liquid catalyst for desulfurization, wherein iron ions: chelating agents are mixed in a molar ratio of 1:3-4. The method of claim 1, wherein oxygen or air is injected into the mixed solution to induce a pH increase. A cleaning tower through which biogas is introduced and discharged;
A spray tube installed inside the washing tower and having a plurality of nozzles for spraying a liquid catalyst;
A catalyst collection tank installed at a lower portion of the washing tower to collect a liquid catalyst sprayed through the nozzle;
A catalyst supply unit connected to an inlet of the injection pipe to supply a liquid catalyst to the injection pipe;
It characterized in that it comprises; a nozzle clogging prevention pipe connected to the outlet of the injection pipe and extending into the interior of the catalyst collection tank to prevent the nozzle from being blocked by solid sulfur in the liquid catalyst flowing into the injection pipe. Biogas pretreatment device. 5. The biogas pretreatment apparatus according to claim 4, further comprising: a rotating injection means connected to the catalyst supply unit to rotate and inject the liquid catalyst into the interior of the washing tower. 5. The biogas pretreatment apparatus according to claim 4, further comprising a turbulent means for turbulent flow of biogas to increase the contact efficiency between the biogas and liquid catalyst moving inside the washing tower. 7. The biogas pretreatment apparatus according to claim 6, wherein the turbulence means is formed to protrude from the inner circumferential surface of the washing tower, but has a plurality of turbulence inducers formed to be curved into a curved surface.

Images