KR102325218B1 - Sulfur recovery apparatus and method having excellent hydrogen cyanide decomposition capability - Google Patents

Abstract

The present invention provides an apparatus and method capable of effectively removing hydrogen cyanide in acid gas, and in detail, the present invention provides an acid gas input unit for inputting an acid gas containing hydrogen sulfide and hydrogen cyanide, a first heat source and a first a first combustion furnace including an air injection unit for burning the acid gas; a decomposition furnace for decomposing ammonia generated in the first combustion furnace; and a second combustion furnace comprising a second heat source and a second air injection unit, wherein the acid gas that has passed through the first combustion furnace and the decomposition furnace is heated at a temperature of 1350 to 1600° C., a sulfur recovery apparatus and method to provide.

Description

Sulfur recovery apparatus and method having excellent hydrogen cyanide decomposition capability

The present invention relates to decomposition of hydrogen cyanide in acid gas, and more particularly, to an apparatus and method for recovering sulfur having excellent hydrogen cyanide decomposition capability.

The coke used in the blast furnace process in the integrated steelworks is produced by indirectly high-temperature carbonization by injecting the coal raw materials mixed with various types of coal in the coke furnace into the coke furnace carbonization chamber. During this high-temperature dry distillation process, organic and inorganic compounds in the coal are emitted, which is Coke oven gas (COG). The coke oven gas contains tar, hydrocarbons, hydrogen, sulfur compounds, and the like, and through its refining, refined coke oven gas that can be used as a fuel for the steelmaking process is produced. Since the above COG contains a large amount of impurities such as hydrogen sulfide, a method for purifying COG is required. In the above method, the hydrogen sulfide component is removed from the COG by a method of wet scrubbing _{ammonia water (NH 3 ).}

However, since hydrogen sulfide removal in COG using ammonia water does not selectively remove only hydrogen sulfide, but is collected together with carbon dioxide and hydrogen cyanide contained in COG, in the process of regenerating the ammonia water, not only hydrogen sulfide but also ammonia and hydrogen cyanide are gas is released in the form of

In order to recover sulfur from the gas discharged as described above, as in Korean Patent Registration No. 0812706, a process of making and recovering liquid sulfur from the hydrogen sulfide using a Claus Furnace is widely used.

An object of the present invention is to provide an apparatus and method capable of effectively removing hydrogen cyanide in acid gas.

In one aspect of the present invention, the present invention includes an acid gas input unit for inputting an acid gas containing hydrogen sulfide and hydrogen cyanide, a first heat source and a first air injection unit, and a first combustion furnace for burning the acid gas. ; a decomposition furnace for decomposing ammonia generated in the first combustion furnace; and a second combustion furnace comprising a second heat source and a second air injection unit, and heating the acid gas that has passed through the first combustion furnace and the decomposition furnace at a temperature of 1350 to 1600° C., providing a sulfur recovery device .

In another aspect of the present invention, the present invention provides a first combustion step of burning an acid gas containing hydrogen sulfide and hydrogen cyanide; a decomposition step of decomposing ammonia generated in the first combustion step; and a second combustion step of heating the acid gas having performed the first combustion step and the decomposition step at 1350 to 1600° C., providing a sulfur recovery method.

The present invention can improve the efficiency of sulfur recovery by effectively removing hydrogen cyanide in the gas generated in the process of regenerating ammonia water used in the hydrogen sulfide removal process of coke oven gas.

1 shows the decomposition rate of hydrogen cyanide according to temperature.
Figure 2 (a) shows a schematic diagram of a conventional sulfur recovery device, Figure 2 (b) shows the temperature of each zone of the conventional sulfur recovery device.
Figure 3 (a) shows a schematic diagram of the sulfur recovery device of the present invention, Figure 3 (b) shows the temperature for each zone of the sulfur recovery device of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

COG generated in the coke oven has the components shown in Table 1 below.

ingredient H ₂ CO CH ₄ CO ₂ C ₂ H ₆ H ₂ S NH ₃ HCN H ₂ O benzol tar Sum volume% 56.3 8.1 25.1 1.4 2.2 0.8 2.6 0.3 0.0 1.1 2.1 100.0

In order to use COG having the above components for power generation or fuel in a steel mill, it is necessary to remove impurities such as tar or hydrogen sulfide.

In the general purification process of COG gas, tar is first removed through gas cooling and electrostatic precipitation, hydrogen sulfide in the gas is removed with low concentration (2-3%) ammonia water, and finally, aromatic compounds are removed and supplied where necessary.

Here, the process of removing hydrogen sulfide using ammonia water does not selectively remove only hydrogen sulfide, but also collects carbon dioxide, hydrogen cyanide, etc. contained in the COG.

Furthermore, in order to reuse the ammonia water used in the process of removing hydrogen sulfide as described above, the used ammonia water is not used once and discarded, but is recycled and recycled with high concentration ammonia water. It is carried out by heating to a temperature of 100 to 130 ℃ to remove the generated gas. However, as described above, since not only hydrogen sulfide but also carbon dioxide and hydrogen cyanide are captured in the ammonia water used for COG purification, the gas generated in the regeneration process as described above includes not only hydrogen sulfide but also carbon dioxide and hydrogen cyanide.

On the other hand, if the gas generated in the process of regenerating ammonia water as described above is discharged as it is, since air pollution by hydrogen sulfide or the like may occur, a process of recovering sulfur from the gas should be performed.

For this sulfur recovery process, the gas is supplied to a Claus furnace, and hydrogen sulfide in the supplied gas is subjected to partial combustion reactions (reaction formula (1)) and reduction reactions (reaction formulas (2) and (3)) is recovered as sulfur.

H ₂ S+3/2O ₂ (Air)→SO ₂ +H ₂ O ΔH= -518 kJ ... Scheme (1)

2H ₂ S+SO ₂ →3/2S ₂ +2H ₂ O ΔH= + 47 kJ (high temperature) ... Scheme (2)

2H ₂ S+SO ₂ →3/8S ₈ +2H ₂ O ΔH= -108 kJ (low temperature) ... Scheme (3)

However, the hydrogen sulfide concentration in the gas is 20% or less, the hydrogen sulfide concentration is low and the concentration of impurities such as carbon dioxide, ammonia, hydrogen cyanide, and moisture is high. Therefore, the reaction as in Reaction Formulas (1) to (3) may be hindered by the impurities as described above, and the sulfur recovery rate is lowered.

Among them, hydrogen cyanide is particularly difficult to decompose, and undecomposed hydrogen cyanide produces ammonia through the reactions of the following Reaction Formulas (4) and (5).

HCN+H ₂ O→CO+NH ₃ ΔH= -50.7 kJ ... Scheme (4)

HCN+2H ₂ S+1/2O ₂ →CS ₂ +NH ₃ +H ₂ O ΔH= -262.3 kJ ... Scheme (5)

The ammonia thus generated reacts with the sulfur oxide formed by the reaction formula (1) to form an ammonium salt (NH ₄ HSO ₄ , (NH ₄ ) ₂ SO ₄ ). Furthermore, the ammonium salts are deposited in the form of salts on the catalyst used for sulfur recovery, causing deactivation of the catalyst, and as a result, reducing the sulfur recovery efficiency.

Therefore, in order to improve the sulfur recovery efficiency, a process of removing hydrogen cyanide is required.

To this end, the present invention provides a sulfur recovery device having an excellent hydrogen cyanide removal rate.

In detail, the present invention includes an acid gas input unit for inputting an acid gas containing hydrogen sulfide and hydrogen cyanide, a first heat source and a first air injection unit, the first combustion furnace for burning the acid gas; a decomposition furnace for decomposing ammonia generated in the first combustion furnace; and a second combustion furnace comprising a second heat source and a second air injection unit, and heating the acid gas that has passed through the first combustion furnace and the decomposition furnace at a temperature of 1350 to 1600° C., providing a sulfur recovery device .

At this time, the acid gas may be a gas generated in the process of regenerating the aqueous ammonia used for the removal of hydrogen sulfide as described above. Therefore, the acid gas of the present invention may be a gas generated in the process of regenerating ammonia water used in the hydrogen sulfide removal process of the coke oven gas, but is not limited thereto, and any gas may be used as long as it contains hydrogen sulfide and hydrogen cyanide. have.

On the other hand, the first combustion furnace of the present invention may be at a temperature of 500 to 1,100 ℃, for this, air may be injected into the first combustion furnace through the first air injection unit. The amount of air injected may be 1.1 to 1.8 times the volume of the acid gas injected through the acid gas input unit, but is not limited thereto. Suffice.

However, it is difficult to heat the first combustion furnace to 1,100° C. or higher for reasons such as moisture in the acid gas and thermal durability of the catalyst used in the cracking furnace at the rear stage. Therefore, 100% of hydrogen cyanide in the acid gas is not thermally decomposed, and undecomposed hydrogen cyanide remains.

Accordingly, some of the undecomposed hydrogen cyanide among the acid gas injected into the first combustion furnace may undergo the same reaction as in Reaction Formulas (4) and (5), thereby forming ammonia. However, although the ammonia may be removed through thermal decomposition in the first combustion furnace, not all ammonia is removed, so an apparatus for decomposing the undecomposed hydrogen cyanide and the ammonia may be used.

Accordingly, the present invention includes a decomposition furnace for decomposing ammonia generated in the first combustion furnace, and the decomposition furnace can decompose the ammonia into harmless N ₂ and water. Furthermore, it is possible to decompose a portion of the undecomposed hydrogen cyanide, but the efficiency of decomposing the undecomposed hydrogen cyanide is not high.

As the catalyst used in the cracking furnace, catalysts used in the art may be used without limitation, and as described above, ammonia generated in the first combustion furnace is mostly removed by the catalyst for cracking ammonia in the cracking furnace.

However, since hydrogen cyanide in the acid gas is not all decomposed and removed even through the first combustion furnace and the decomposition furnace, it is necessary to perform additional combustion.

Accordingly, the present invention includes a second furnace for further combustion. The second combustion furnace may include a second heat source and a second air injection unit, and the acid gas passing through the first combustion furnace and the decomposition furnace may be heated at a temperature of 1350 to 1600°C.

Specifically, the second heat source may be used without limitation as long as it is a device capable of increasing the temperature of the second combustion furnace. For example, a device such as an electric heater may be used as the second heat source.

In order for the acid gas to flow smoothly, the second heat source may be in the form of a sieve. In addition, the second heat source may be installed in the vertical direction of the acid gas flow. Due to the heat source in the form of a sieve and the heat source installed in the vertical direction, the acid gas may be uniformly heated and burned by the heat source.

Furthermore, the second heat source may be installed at a position where the radius (R) of the second combustion furnace / the distance (L) from the second air injection unit to the second heat source is 1 to 2, but is not limited thereto, It may be installed at a distance so that a space necessary for combustion of oxygen injected from the second air injection unit is secured.

Meanwhile, the second air injection unit may further increase the temperature of the second combustion furnace and inject oxygen for the thermal decomposition of hydrogen cyanide. In addition, the second air injector may inject the oxygen using a plurality of nozzles.

At this time, the plurality of nozzles are installed symmetrically with respect to the center of the second combustion furnace so that the second combustion furnace is uniformly heated so that pyrolysis of hydrogen cyanide can be uniformly performed inside the second combustion furnace. can be When oxygen for combustion is asymmetrically injected into the second combustion furnace, the thermal decomposition reaction of hydrogen cyanide may be performed relatively low in a portion of the inside of the second combustion furnace, and thus the overall hydrogen cyanide decomposition effect may be reduced.

In addition, it is preferable that oxygen in the air injected into the first combustion furnace is 5 to 20 times that of oxygen injected into the second combustion furnace. For example, the volume ratio of oxygen in the air injected into the first combustion furnace / oxygen injected into the second combustion furnace is 2 to 4 (70 to 80% of oxygen in the air injected into the first combustion furnace, in the second combustion furnace) 20 to 30% of injected oxygen). In order to thermally decompose impurities in the initial acid gas and burn some hydrogen sulfide through the reaction as in (1) above, the oxygen input amount is higher than that of the second combustion furnace.

And, in order to perform the same reaction as (2) and (3) in the sulfur recovery process proceeding after the second combustion furnace, it is necessary to set the H ₂ S/SO ₂ ratio to 1.5 to 2.5, preferably 2 Therefore, it is possible to adjust the amount of oxygen injected into the second combustion furnace in consideration _{of the H 2} S/SO ₂ ratio of the gas discharged from the second combustion furnace.

Furthermore, the present invention can control the temperature of the second combustion furnace by installing a temperature sensor before and after the second heat source to adjust the output amount of the second heat source. If the temperature before reaching the second heat source (oxygen combustion region) is less than 1,350°C, power can be supplied to the second heat source to increase the temperature, and when the temperature of the acid gas passing through the second heat source is 1,350°C or higher By stopping or controlling the supply of power supplied to the second heat source, the temperature of the second combustion furnace may be adjusted. However, for efficient decomposition of hydrogen cyanide, it is preferable to adjust the temperature to 1,600° C. or less. Since there is no difference in the decomposition rate of hydrogen cyanide even if it exceeds 1,600° C., it is preferable to heat the second combustion furnace below the above temperature for economic reasons.

On the other hand, the present invention provides a sulfur recovery method capable of providing excellent sulfur recovery efficiency from an acid gas containing hydrogen sulfide and hydrogen cyanide.

Specifically, a first combustion step of burning an acid gas containing hydrogen sulfide and hydrogen cyanide; a decomposition step of decomposing ammonia generated in the first combustion step; and a second combustion step of heating the acid gas having performed the first combustion step and the decomposition step at 1350 to 1600° C., providing a sulfur recovery method.

Since the detailed description and operation of the first combustion step, the decomposition step, and the second combustion step have already been described in the above-described sulfur recovery device, the following will be omitted.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

Comparative Example 1

Gas (including ammonia, carbon dioxide, hydrogen cyanide, and hydrogen sulfide) generated in the process of regenerating ammonia water used in the hydrogen sulfide removal process of coke oven gas was injected into the Claus furnace of the form shown in FIG. 1 . The composition of acid gas generated during the regeneration of ammonia water is as follows.

ingredient CO ₂ H ₂ S NH ₃ HCN H ₂ O volume% 15-20 15-20 30-40 2-8 30-40

Oxygen was injected through the first air injection unit 3 of FIG. 2A , and the gas was injected through the acid gas injection unit 2 . Thereafter, the first decomposition of hydrogen cyanide by oxygen was performed in the first combustion furnace (1-a), and ammonia produced by the decomposition was decomposed in the decomposition furnace (1-b). Further, combustion for decomposing the hydrogen cyanide remaining in the second combustion furnace (1-c) was performed.

In the first combustion furnace (1-a), decomposition was performed at a temperature of 500 to 1100 °C, and in the second combustion furnace (1-c), decomposition was performed at a temperature of 1100 to 1150 °C. The temperature for each section is shown in FIG. 2(b).

The combustion-completed gas is discharged through the discharge path 6, and sulfur is recovered from the discharged gas.

Example 1

In Comparative Example 1, by installing an additional heat source and an air injection unit in the second combustion furnace (1-c) portion, the second combustion furnace (1-c) is connected to the second combustion furnace-1 (1-c') and the second Combustion was performed in the same manner as in Comparative Example 1, except that the furnace was separated into 2(1-d).

Specifically, oxygen was injected through the first air injection unit 3 of FIG. 3A , and the gas was injected through the second air injection unit 2 . Thereafter, the first decomposition of hydrogen cyanide by oxygen was performed in the first combustion furnace (1-a), and ammonia produced by the decomposition was decomposed in the decomposition furnace (1-b). Further, combustion for decomposing hydrogen cyanide remaining in the second combustion furnace-1(1-c') and the second combustion furnace-2(1-d) was performed.

The first combustion furnace (1-a) was decomposed at a temperature of 500 to 1100 °C, and in the second furnace-1 (1-c') and the second combustion furnace-2 (1-d), 1100 to 1350 Decomposition was carried out at a temperature of °C. The temperature for each section is shown in FIG. 3(b).

As a result, the hydrogen cyanide content of the gas discharged through the discharge path 6 of FIGS. 2(a) and 3(a) was measured, and the While the content of hydrogen cyanide is 2,000 to 5,000 ppm, the hydrogen cyanide content of the gas discharged through the discharge path 6 of FIG. 3 (a) is 100 ppm or less, and the hydrogen cyanide decomposition rate by FIG. high was confirmed.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.

1: Klaus Law
2: Acid gas injection part
3: first air inlet
4: second air inlet
5: Second heat source
6: exhaust furnace

Claims (13)

a first combustion furnace comprising an acid gas input unit for inputting an acid gas containing hydrogen sulfide and hydrogen cyanide, a first heat source, and a first air injection unit for burning the acid gas;
a decomposition furnace for decomposing ammonia generated in the first combustion furnace; and
A sulfur recovery device comprising a second combustion furnace comprising a second heat source and a second air injection unit and heating the acid gas that has passed through the first combustion furnace and the decomposition furnace at a temperature of 1350 to 1600°C,
The second air injection unit will inject oxygen into the second combustion furnace, sulfur recovery device.
delete According to claim 1,
The second air injection unit will include a plurality of nozzles, sulfur recovery device.
4. The method of claim 3,
The plurality of nozzles are installed symmetrically with respect to the center of the second combustion furnace, the sulfur recovery device.
According to claim 1,
The second heat source is an electric heater.
According to claim 1,
wherein the second heat source is in the form of a sieve.
According to claim 1,
The second heat source is installed in the vertical direction of the acid gas flow, sulfur recovery device.
According to claim 1,
The second heat source is installed at a position where the radius of the second combustion furnace (R) / the distance (L) from the second air injection unit to the second heat source is 1 to 2, the sulfur recovery device.
a first combustion step of burning an acid gas containing hydrogen sulfide and hydrogen cyanide;
a decomposition step of decomposing ammonia generated in the first combustion step; and
Including a second combustion step of injecting oxygen into the acid gas having performed the first combustion step and the decomposition step, and heating the acid gas to 1350 to 1600°C.
10. The method of claim 9,
The acid gas is a gas generated in the process of regenerating the ammonia water used in the hydrogen sulfide removal process of the coke oven gas, the sulfur recovery method.
10. The method of claim 9,
The first combustion step is carried out at a temperature of 500 to 1,100 ℃, sulfur recovery method.
delete 10. The method of claim 9,
The second combustion step is to heat the acid gas that has performed the first combustion step and the decomposition step, the sulfur recovery method.

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