WO2018147421A1 - System for removing hydrogen sulfide and method for removing hydrogen sulfide - Google Patents

Abstract

A system 1 for removing hydrogen sulfide, which is characterized by comprising: a hydrogen sulfide separation device 30 which separates a starting material gas containing hydrocarbon and hydrogen sulfide into a first gas that has a lower hydrogen sulfide concentration than the starting material gas and a second gas that has a higher hydrogen sulfide concentration than the starting material gas; and a sulfuric acid production device 50 which produces sulfuric acid with use of the second gas.

Description

Hydrogen sulfide removal system and hydrogen sulfide removal method

The present invention relates to a hydrogen sulfide removal system and a hydrogen sulfide removal method.
This application claims priority based on Japanese Patent Application No. 2017-022015 for which it applied to Japan on February 9, 2017, and uses the content here.

The oil-field associated gas and natural gas produced during oil production include methane and other hydrocarbons, which are the main components, as well as moisture, nitrogen gas, carbon dioxide, hydrogen sulfide, etc. Is included). Among these, carbon dioxide forms, for example, CO ₂ hydrate and causes clogging of pipelines and the like. Further, hydrogen sulfide causes corrosion of the pipeline in addition to its toxicity and odor, so it is required to make the concentration as low as possible (for example, less than 20 ppm).

As a technique for removing hydrogen sulfide contained in natural gas, absorption separation (amine absorption method) using a base such as amine is known. For example, Patent Document 1 proposes a technique for selectively removing hydrogen sulfide from natural gas using t-butylamine and polyethylene glycol as adsorbents. In the technique of Patent Document 1, an absorption tower that contains an absorption liquid that absorbs hydrogen sulfide in a mined natural gas, and a regeneration tower that regenerates the absorption liquid that has absorbed hydrogen sulfide into an absorption liquid that does not contain hydrogen sulfide. A facility consisting of The mined natural gas (unrefined gas) enters the absorption tower and counter-contacts with the absorption liquid flowing down from the upper part in the tower to remove hydrogen sulfide, and becomes purified gas. The absorption liquid that has absorbed the hydrogen sulfide is sent to the regeneration tower, where it is regenerated by releasing the hydrogen sulfide under reduced pressure and heating, and then recycled to the absorption tower.
The separation gas separated by the amine absorption method does not contain hydrocarbons such as methane, and the separation gas may contain hydrogen sulfide. In this case, a certain amount of air is blown into the separation gas by the Claus method or the like to oxidize highly toxic hydrogen sulfide, thereby recovering simple sulfur and selling it as a by-product.

On the other hand, separation membranes and the like are widely known as techniques for separating chemical species in a gas by utilizing the difference in gas permeability according to the type of gas. For example, Patent Document 2 proposes a technique for separating acidic gas containing hydrogen sulfide from natural gas using a separation membrane having a larger permeation rate of acidic gas than methane. If this separation membrane is used, a component containing a high-concentration acidic gas that has permeated the membrane and a component containing a low-concentration acidic gas that does not permeate the membrane can be obtained by bringing the pressurized gas to be treated into contact with the separation membrane. Can be separated.
Patent Document 2 describes a polyorganosiloxane separation membrane that separates hydrogen sulfide and carbon dioxide from methane. This separation membrane separates the acidic gas by utilizing the difference in the speed of permeation through the polyorganosiloxane membrane between methane, hydrogen sulfide and carbon dioxide, pressurizing the mixed gas of methane and acidic gas, Separation is performed by utilizing the fact that the acidic gas concentration of the gas component that has permeated through the separation membrane is increased by bringing it into contact with the separation membrane.

US Patent Application Publication No. 2015/0122125 Japanese Patent No. 2718681

However, in the technique of Patent Document 1, the amount of the solution for absorption increases in proportion to the hydrogen sulfide concentration of the natural gas entering the absorption tower. When the amount of absorption solution circulation increases, it becomes necessary to use a large absorption tower / regeneration tower, and steam in the reboiler that heats the absorption tower / regeneration tower in proportion to the increase in the size of the absorption tower / regeneration tower Consumption increases. In the amine absorption method, a large amount of water vapor is required to regenerate the absorbing solution, and the amount of heat is required to be about 4 GJ / t (CO ₂ ). Therefore, when the content of acidic gas in the output gas is high, removal is necessary. A lot of energy is required.
Previously, when mining natural gas, high-quality natural gas with a relatively low concentration of acid gas (approximately less than 10% by volume) was selectively mined. Low-quality natural gas with a high content concentration is also subject to mining and production, and the energy cost of acid gas removal is a problem. Therefore, large energy is required in the process of separating and removing hydrogen sulfide from the unpurified gas.

Acid gas removal by a separation membrane represented by Patent Document 2 is based on the gas permeability of the separation membrane or the like, and therefore, compared to the amine absorption method, a large amount of hydrocarbon components such as methane are contained in a high concentration acidic gas component. included. For this reason, even if hydrogen sulfide contained in the acidic gas component is oxidized with a certain amount of oxygen to produce sulfur, the resulting sulfur is a mixture with hydrocarbon-derived carbon particles, and its commercial value is small. . In addition, since this mixture is difficult to process, even if the techniques of Patent Document 1 and Patent Document 2 are combined, the sulfur component cannot be effectively used.
Accordingly, an object of the present invention is to provide a hydrogen sulfide removal system and a hydrogen sulfide removal method capable of saving energy and effectively using a sulfur component when removing hydrogen sulfide contained in natural gas.

The present invention has the following aspects.
[1] A source gas containing hydrocarbon and hydrogen sulfide is changed into a first gas having a hydrogen sulfide-containing concentration lower than that of the source gas and a second gas having a hydrogen sulfide-containing concentration higher than that of the source gas. A hydrogen sulfide removal system comprising: a hydrogen sulfide separation device for separation; and a sulfuric acid production device for producing sulfuric acid using the second gas.
[2] A hydrogen sulfide removing device for removing hydrogen sulfide contained in the first gas is further provided on the secondary side of the hydrogen sulfide separating device, and the hydrogen sulfide separating device uses a separation membrane. The hydrogen sulfide removal system according to [1].
[3] The hydrogen sulfide according to [1] or [2], further comprising a pipe capable of supplying the source gas to the sulfuric acid production apparatus on a primary side of the hydrogen sulfide separator. Removal system.
[4] The hydrogen sulfide according to any one of [1] to [3], further comprising a pretreatment device capable of treating the source gas on the primary side of the hydrogen sulfide separation device Removal system.

Furthermore, this invention has the following aspects.
[5] Separating a raw material gas containing hydrocarbon and hydrogen sulfide into a first gas having a lower hydrogen sulfide content concentration than the raw material gas and a second gas having a higher hydrogen sulfide content concentration than the raw material gas And a step of producing sulfuric acid using the second gas. A method for removing hydrogen sulfide, comprising:
[6] The method for removing hydrogen sulfide according to [5], further comprising a step of removing hydrogen sulfide contained in the first gas using a separation membrane.
[7] The method for removing hydrogen sulfide according to [5] or [6], further comprising a step of using the raw material gas when the hydrocarbon is insufficient in the step of producing the sulfuric acid.
[8] The method for removing hydrogen sulfide according to any one of [5] to [7], further comprising a step of treating the source gas before the step of separating hydrogen sulfide.

According to the hydrogen sulfide removal system of the present invention, when removing hydrogen sulfide contained in natural gas, energy can be saved and the sulfur component can be effectively used.

1 is a system diagram showing a configuration of a hydrogen sulfide removal system that is an embodiment to which the present invention is applied. It is a systematic diagram which shows the structure of the hydrogen sulfide removal system which is other embodiment to which this invention is applied. It is a systematic diagram which shows the structure of one Embodiment of the conventional hydrogen sulfide removal system.

Hereinafter, a hydrogen sulfide removal system as an embodiment to which the present invention is applied and a hydrogen sulfide removal method using this system will be described in detail with reference to the drawings. Note that the drawings referred to in the following description may show the enlarged characteristic portions for convenience in order to make the features easy to understand, and the dimensional ratios of the respective components are the same as the actual ones. Not necessarily.

<Hydrogen sulfide removal system>
First, the hydrogen sulfide removal system 1 of this embodiment will be described. FIG. 1 is a system diagram showing a configuration of a hydrogen sulfide removal system 1 which is an embodiment to which the present invention is applied. As shown in FIG. 1, the hydrogen sulfide removal system 1 of the present embodiment includes a raw material supply source 10, a pretreatment device 20, a hydrogen sulfide separation device 30, a hydrogen sulfide removal device 40, a sulfuric acid production device 50, The exhaust gas treatment device 60 and the pipes L0 to L12 are schematically configured.

The hydrogen sulfide removal system 1 of this embodiment removes hydrogen sulfide from a raw material gas containing hydrocarbons and hydrogen sulfide, and removes purified hydrocarbons as a third gas (target gas). A system for producing sulfuric acid from hydrogen sulfide.

(Raw material supply source)
The raw material supply source 10 is a supply source that supplies a raw material gas containing hydrocarbons and hydrogen sulfide to the hydrogen sulfide removal system 1.
The raw material gas only needs to contain hydrocarbons and hydrogen sulfide, and is not particularly limited. For example, natural gas extracted, liquefied petroleum gas obtained when refining petroleum, or oil produced in production. Oil field associated gas, coal bed methane (CBM) that can be collected from a coal bed, coke oven gas obtained when coal is carbonized in a coke oven, and the like. The source gas may contain a gas such as carbon dioxide, nitrogen, and helium in addition to hydrocarbon and hydrogen sulfide. In particular, carbon dioxide is collectively processed as an acid gas together with hydrogen sulfide.

In the hydrogen sulfide removal system 1 of the present embodiment, the total concentration of acid gas and inert gas such as nitrogen is 85% or less (hereinafter referred to as concentration unit “volume”, depending on the price of natural gas / sulfuric acid and the plant scale. % ”Is simply expressed as“% ”), which is advantageous in terms of energy balance. Further, if the total concentration of acid gas and inert gas such as nitrogen is 70% by volume or less, it is possible to operate the system while ensuring sufficient profitability in addition to the above advantages. Benefits are gained. In addition, when the hydrogen sulfide gas concentration is 0.5% or more, the superiority over the conventional method becomes significant. In this system, the total concentration of acid gas and inert gas such as nitrogen is 10 to 85%, Preferably, it is suitable to use a source gas having a hydrogen sulfide gas concentration of 0.5% or more with 10 to 70%.
The raw material supply source 10 only needs to be able to supply the raw material gas, such as an oil and gas field ground facility, a pipeline connected thereto, a tank capable of temporarily storing the raw material gas, a movable tank-equipped vehicle, and the like. It can also be applied to the front stage of an LNG (Liquid Natural Gas) plant, biogas, and the like.

The raw material supply source 10 and the pretreatment device 20 are connected by a pipe L0 for introducing a raw material gas, and the raw material gas is supplied from the pretreatment device 20 to the hydrogen sulfide separation device 30 via the pipe L1.
A branch 101 is provided in the pipe L0 and is connected to the pipe L7.
Examples of the pipe L0, the pipe L1, and the pipe L7 include metal or resin pipes, but are not limited to these pipes. Moreover, the material of each piping may be the same as that of other piping, and may differ. Hereinafter, the types and materials of the piping in this specification are the same.

(Pretreatment device)
The pretreatment device 20 is a device that converts an organic sulfur component contained in the raw material gas into hydrogen sulfide in advance when the raw material gas is supplied to the hydrogen sulfide separation device 30.
In addition to hydrogen sulfide, the raw material gas may contain organic sulfur components in various forms. As organic sulfur components other than hydrogen sulfide, organic sulfur compounds (especially mercaptans) in which sulfur atoms are combined with various hydrocarbons are known.
When mercaptan is contained in the raw material gas, the mercaptan cannot be separated by the hydrogen sulfide separation device 30 described later. Therefore, mercaptan is contained in the first gas having a lower hydrogen sulfide content concentration than the source gas and the second gas having a higher hydrogen sulfide content concentration than the source gas, thereby sufficiently removing the organic sulfur component. I can't.
Therefore, in the pretreatment device 20, it is preferable to perform a process of reacting the raw material gas with a mixed gas of hydrogen and carbon dioxide to convert mercaptan in the raw material gas into hydrogen sulfide.
By converting the organic sulfur component in the raw material gas into hydrogen sulfide in advance, the organic sulfur component in the target gas can be further reduced.

As the pretreatment device 20, a known device for converting mercaptan into hydrogen sulfide may be used. For example, an apparatus in which an adiabatic reactor that reforms a raw material gas at a low temperature by using a nickel-based special catalyst and a hydrogenation reactor that hydrosulfates a mercaptan is used.

(Hydrogen sulfide separator)
The hydrogen sulfide separation device 30 includes a raw material gas containing hydrocarbon and hydrogen sulfide, a first gas having a lower hydrogen sulfide content concentration with respect to hydrocarbon than the raw material gas, and hydrogen sulfide with respect to hydrocarbon than the raw material gas. It is an apparatus for separating into a second gas having a high content concentration.
The first gas has a hydrogen sulfide content concentration of preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less in terms of energy required for the operation of the hydrogen sulfide removing device 40 described later. The concentration of hydrogen sulfide is preferably from 0.1% to 10%, more preferably from 0.1% to 5%, and even more preferably from 0.1% to 1%.
The second gas has a higher hydrogen sulfide content concentration than the source gas. The second gas generally contains a certain amount of methane as a hydrocarbon. Since the second gas is introduced into the combustion apparatus 501 in the sulfuric acid production apparatus 50 described later, it is preferable that the second gas contains 10% or more of hydrogen sulfide and hydrocarbon gas as a combustible gas in total. The total amount of hydrogen sulfide and hydrocarbon gas contained in the second gas is more preferably 10% or more and 50% or less.

The hydrogen sulfide separation device 30 is not particularly limited as long as the source gas can be separated into the first gas and the second gas, and a known device for separating hydrogen sulfide can be used. For example, an apparatus that adsorbs and separates with activated carbon or the like may be used, but it is possible to perform separation of carbon dioxide in the raw material gas together with hydrogen sulfide with less energy consumption than the adsorption separation method. In addition, since a certain amount of combustible gas can be contained in the second gas, a hydrogen sulfide separation device using a separation membrane is preferable.

In the present embodiment, the separation membrane refers to a permeator having a structure having a difference in transmittance depending on the type of gas due to a fine through hole or the like and having gas permeability. Examples of the mechanism include a mechanism for controlling the transmittance according to the relationship between the size of the through hole and the molecule, and a mechanism for utilizing an average free process based on the molecular weight of the gas. As a material for the separation membrane, various materials such as ceramics such as zeolite, polyimide, organic compounds such as cellulose, silicone, and fluorine-based polymers can be used. Examples of the form of the separation apparatus using the separation membrane include forms provided as various separation membrane modules such as a cylindrical shape, a hollow fiber, a flat plate, or a bag-like separation membrane wound into a cylindrical shape. These separation membranes can be selected according to the price of the raw material gas, the price of a hydrocarbon gas such as methane as the product gas, and the like.

The hydrogen sulfide separation device 30 is connected to the hydrogen sulfide removal device 40 via the pipe L2, and the first gas is supplied from the hydrogen sulfide separation device 30 to the hydrogen sulfide removal device 40.
Further, the hydrogen sulfide separation device 30 is connected to the sulfuric acid production device 50 via the pipe L3, and the second gas is supplied from the hydrogen sulfide separation device 30 to the sulfuric acid production device 50.

(Hydrogen sulfide removal equipment)
The hydrogen sulfide removing device 40 is a device that is provided on the secondary side of the hydrogen sulfide separating device 30 and removes hydrogen sulfide contained in the first gas. In the hydrogen sulfide removing device 40, the first gas is removed from the corrosive component and sent to the pipe L4 as the target gas. The target gas is separated into an inert gas such as nitrogen or helium, hydrocarbons other than methane, and methane in a LNG production process or the like as necessary, and shipped as a product.
The concentration of hydrogen sulfide contained in the target gas is preferably 100 ppm (volume basis) or less, more preferably 30 ppm or less, still more preferably 10 ppm or less, and particularly preferably 4 ppm or less. When the concentration of hydrogen sulfide in the target gas is 100 ppm or less, there is an advantage that the possibility of olfactory paralysis is reduced even when exposed to the target gas leaked in a leakage accident or the like. In addition to the advantages, there is an advantage that the risk of respiratory tract irritation, conjunctivitis and the like is reduced, and when it is 4 ppm or less, there is an advantage that it can be shipped as a raw material gas for a gas pipeline.
The concentration of hydrogen sulfide is most preferably 0 ppm, but if it is less than the above upper limit, the above-described advantages can be ensured, so that it is more than 0 ppm in consideration of economics when reducing to 0 ppm. There may be.

The hydrogen sulfide removing device 40 is not particularly limited, and a known device for removing hydrogen sulfide can be used. For example, a device using a chemical absorption oxidation regeneration method, a removal device using an amine absorption method, or the like using a solution of a small amount of picric acid dissolved in a sodium carbonate aqueous solution, caustic soda, or an ammoniacal alkaline aqueous solution can be used. Among these, a removal apparatus using an amine absorption method widely used for removing acidic gas is practically preferable because it can remove carbon dioxide simultaneously with hydrogen sulfide.

In the hydrogen sulfide removing apparatus 40 using the amine absorption method, the first gas is brought into contact with the amine absorbing solution in the amine absorption tower 401, and hydrogen sulfide is removed. Thereby, the purified target gas can be taken out from the pipe L4. On the other hand, the absorbing liquid that has absorbed hydrogen sulfide is introduced into the amine regeneration tower 402 via the pipe L41, and is heated in the amine regeneration tower 402, thereby releasing hydrogen sulfide and carbon dioxide (acidic gas). The amine absorbing liquid from which the acid gas has been released is sent again from the pipe L42 to the amine absorption tower 401 via the compressor 403 and the pipe L43.
Further, the removed hydrogen sulfide is pressurized by a compressor (not shown) through the pipe L5 and then supplied to the sulfuric acid production apparatus 50.

In the pipe L5, in order to prevent hydrogen sulfide from flowing out of the amine regeneration tower 402 during maintenance, and to prevent unintended gas from flowing back to the amine regeneration tower 402 via the pipes L7 and L3 at the start, A check valve 80 is provided. Further, when the flow rate of the pipes L7 and L3 suddenly increases during operation or the combustible gas composition increases, the entire hydrogen sulfide removal system 1 is maintained while the combustion state of the combustion device 501 is stabilized by restricting the on-off valve 70. It is possible to obtain a time margin for adjusting the operating conditions.
The check valve 80 may be manual or automatic, but is preferably an automatic check valve 80 from the viewpoint of facility management. The on-off valve 70 may be the same type as the check valve 80 or may be a different type.

(Sulfuric acid production equipment)
The sulfuric acid production apparatus 50 is an apparatus that produces sulfuric acid using a sulfur component as a raw material. The sulfuric acid production apparatus 50 is not particularly limited, and a known apparatus for producing sulfuric acid can be used. For example, a sulfur combustion type (contact method) apparatus, a metallurgical type apparatus, an apparatus using coke oven gas desulfurization sulfur as a raw material, an apparatus using coke oven sour gas as a raw material, and the like can be mentioned.
Below, the sulfuric acid manufacturing apparatus 50 by a sulfur combustion type (contact method) is demonstrated.
The sulfuric acid manufacturing apparatus 50 is connected to the pipe L3, the pipe L5, and the pipe L6, respectively.
The second gas obtained by the hydrogen sulfide separation device 30 is supplied from the pipe L3. Hydrogen sulfide removed by the hydrogen sulfide removing device 40 is supplied from the pipe L5. The second gas and hydrogen sulfide are merged at the branch 103 provided in the pipe L3, and the amount of heat is adjusted, and then supplied to the sulfuric acid production apparatus 50 as a fuel gas. The fuel gas is a mixture of hydrocarbons such as hydrogen sulfide and methane. The fuel gas is supplied to the combustion device 501 via the pipe L3. The fuel gas is combusted by air, and the hydrocarbon and hydrogen sulfide become a combustion gas composed of carbon dioxide, water, sulfur dioxide, nitrogen and a small amount of nitrogen oxide. Since the combustion gas is usually 1000 ° C. or higher, the heat recovery device 502 provided in the pipe L51 recovers heat as high-temperature water vapor, and then is supplied to the dehydration device 503. After the moisture is removed by the dehydrator 503, the combustion gas is supplied to the converter 504 via the pipe L53. The water removed by the dehydrator 503 is partly or wholly merged with the water supplied from the water supply means 11 and the pipe L12 as necessary via the pipe L58 at the branch 112, and the concentrated sulfuric acid dilution apparatus. 507 is supplied. Concentrated sulfuric acid produced in the absorption tower 506 is hydrated by the concentrated sulfuric acid diluting device 507, circulates through the pipe L57, and returns to the absorption tower 506, so that it is finally recovered as concentrated sulfuric acid.

In the converter 504, sulfur dioxide in the dehydrated combustion gas is converted into sulfur trioxide (SO ₃ , also called sulfuric anhydride) by the introduced oxygen in the air and the vanadium pentoxide (V ₂ O ₅ ) catalyst. It is oxidized and supplied to the absorption tower 506 via the pipe L54, the heat recovery device 505, and the pipe L55 as converted gas together with other gases.
In these processes, the converter 504 manages combustion conditions and the like so that the catalyst layer has a predetermined temperature (usually about 450 ° C. at the catalyst layer inlet and about 600 ° C. at the catalyst layer outlet). In the recovery device 505, heat recovery is appropriately performed.
The sulfur trioxide contained in the conversion gas is absorbed by the sulfuric acid in the absorption tower 506 and becomes concentrated sulfuric acid having a high added value.

The heat generated in the above process is recovered by the heat recovery apparatus 502 installed in the pipe L51 and the heat recovery apparatus 505 installed between the pipe L54 and the pipe L55. The heat recovered by the heat recovery device 502 joins the pipe L6 at the junction 105 provided in the pipe L6 via the pipe L52. The heat recovered by the heat recovery device 505 joins the pipe L6 at the junction 104 provided in the pipe L6 via the pipe L56. The combined heat and the heat generated in the absorption tower 506 are supplied to the hydrogen sulfide removing device 40 via the pipe L6. The supplied heat is used in the amine regeneration tower 402 in the hydrogen sulfide removing device 40, and the surplus heat can be used for power generation and the like, and does not require fuel for amine regeneration. The energy efficiency of the hydrogen sulfide removal system 1 is improved. In particular, when the number of moles of sulfuric acid produced is more than three times the number of moles of acid gas recovered by the hydrogen sulfide removal device 40, the low-temperature exhaust heat generated at the absorption tower 506 at a temperature lower than 300 ° C. At 402, the required amount of heat is exceeded. In this case, during steady operation, the amount of heat used for amine regeneration in the amine regeneration tower 402 can be covered by the low-temperature exhaust heat generated in the absorption tower 506, so that the high temperature recovered by the heat recovery devices 504 and 505. The recovered heat can be used for power generation and the like, and the energy efficiency of the hydrogen sulfide removal system 1 is further improved.

As the heat recovery device 502, a known device can be used, and examples include a heat exchanger and an exhaust heat recovery device. The recovered heat may be supplied as steam or as hot water. The heat recovery apparatuses 502 and 505 may be the same type or different types.

The concentrated sulfuric acid produced by the sulfuric acid production apparatus 50 is taken out through the pipe L8. The pipe L8 is provided with a branch 106 and is connected to the concentrated sulfuric acid diluting device 507 via the pipe L57.
The gas after the sulfur trioxide is removed by the absorption tower 506 contains nitrogen oxide, sulfur dioxide, residual sulfur trioxide, sulfuric acid mist, etc. in addition to nitrogen and carbon dioxide. It is discharged appropriately through the device 60.

The pipe L <b> 7 is a pipe capable of supplying the raw material gas to the sulfuric acid production apparatus 50 from the branch 101 provided on the primary side of the hydrogen sulfide separation apparatus 30. The pipe L7 joins the pipe L3 at the branch 102 and can supply the raw material gas to the sulfuric acid production apparatus 50 together with the second gas separated by the hydrogen sulfide separation apparatus 30. Further, the pipe L7 may be capable of supplying the raw material gas directly to the sulfuric acid production apparatus 50 without joining the pipe L3.
The pipe L7 may be provided with an on-off valve 70 that adjusts the flow rate according to the combustion state of the combustion device 501. When the internal temperature of the combustion apparatus 501 is high (for example, 1,000 ° C. or higher, preferably 1,300 ° C. or higher, more preferably 1,500 ° C. or higher), the on-off valve 70 is throttled, It is opened when the fuel gas has insufficient heat.
Thereby, the use of the fuel supplied from the outside can be saved, and further energy saving can be achieved.

Examples of the sulfuric acid (industrial sulfuric acid) manufactured in the sulfuric acid manufacturing apparatus 50 include concentrated sulfuric acid, dilute sulfuric acid, fuming sulfuric acid, and purified sulfuric acid.
In the hydrogen sulfide removal system 1 of the present embodiment, in the sulfuric acid production apparatus 50, in addition to the industrial sulfuric acid described above, useful products such as ammonium sulfate and gypsum (CaSO ₄ .2H ₂ O) (hereinafter referred to as “sulfuric acid product”). Also called).

<Method of removing hydrogen sulfide>
Next, the hydrogen sulfide removal method of this embodiment using the above-described hydrogen sulfide removal system 1 will be described. In the hydrogen sulfide removal method of this embodiment, a raw material gas containing hydrocarbon and hydrogen sulfide is prepared by using a first gas having a lower hydrogen sulfide content concentration than the raw material gas and a higher hydrogen sulfide content concentration than the raw material gas. Separated into a second gas, sulfuric acid is produced using the second gas. The hydrogen sulfide removal method of this embodiment further removes hydrogen sulfide contained in the first gas to obtain a target gas. Various product gases are obtained by further purifying the target gas.

The method for removing hydrogen sulfide in the present invention includes the following steps (I) to (IV).
(I) The process of processing source gas.
(II) Separating a raw material gas containing hydrocarbon and hydrogen sulfide into a first gas having a lower hydrogen sulfide content concentration than the raw material gas and a second gas having a higher hydrogen sulfide content concentration than the raw material gas Process.
(III) A step of removing hydrogen sulfide contained in the first gas.
(IV) A step of producing sulfuric acid using the second gas.
The hydrogen sulfide removal method of the present invention can be carried out using the hydrogen sulfide removal system 1 shown in FIG. 1 described above, the hydrogen sulfide removal system 2 shown in FIG. 2 described above, or the like. Moreover, the description regarding FIG.1 and FIG.2 is applicable to the hydrogen sulfide removal method also about the operation conditions and the operation method of each apparatus which comprise a hydrogen sulfide removal system. Therefore, in the following description regarding the hydrogen sulfide removal method, a description of the specific configuration, operation conditions, and operation method of each device constituting the hydrogen sulfide removal system is omitted.

(Process (I))
Step (I) is a step of processing the source gas in the pretreatment device 20. By having the step (I), an organic sulfur component such as mercaptan contained in the raw material gas in advance can be converted into hydrogen sulfide. The raw material gas supplied from the raw material supply source 10 is supplied to the pretreatment device 20 via the pipe L0, and the processed raw material gas is supplied to the hydrogen sulfide separation device 30 via the pipe L1.
By converting the organic sulfur component contained in the raw material gas into hydrogen sulfide, the efficiency of removing the sulfur component in the step (II) described later can be increased. For this reason, it is preferable that the method for removing hydrogen sulfide of the present invention includes the step (I).

As an example of the step (I), a step of hydrogenating an organic sulfur component contained in the raw material gas with a known hydrodesulfurization catalyst using hydrogen gas contained in the raw material gas to convert it into hydrogen sulfide can be mentioned.
In step (I), a part of the raw material gas is reformed using carbon dioxide gas and water vapor by a steam / carbon dioxide (carbon dioxide) reforming method, and carbon monoxide gas and hydrogen gas are used as main components. A step (not shown) for generating a high-temperature synthesis gas. The hydrogen in the synthesis gas generated in this step is used for hydrogenation of the organic sulfur component in the pretreatment device 20.
As the step (I), it is preferable to combine the step of reforming the raw material gas and the step of converting the organic sulfur component into hydrogen sulfide.

(Process (II))
Step (II) is a step of separating the source gas into the first gas and the second gas in the hydrogen sulfide separator 30. By having the step (II), the hydrogen sulfide content concentration of the first gas can be reduced, and the hydrogen sulfide and hydrocarbon content concentrations of the second gas can be increased.
Since the hydrogen sulfide-containing concentration of the first gas is reduced, an apparatus using an amine absorption method can be used as the hydrogen sulfide removal apparatus 40 in step (III) described later.
By containing a large amount of hydrogen sulfide and hydrocarbons in the second gas, the amount of sulfuric acid produced in the sulfuric acid production apparatus 50 can be increased in step (IV) described later. Further, since hydrocarbons can be used as fuel, the use of fuel supplied from the outside can be saved.
The hydrocarbon in the second gas mainly includes methane.
As the step (II), a step of removing hydrogen sulfide using a separation membrane is preferable from the viewpoint of containing a certain amount of combustible gas in the second gas and energy required for separation of hydrogen sulfide.

The raw material gas supplied to the hydrogen sulfide separation device 30 via the pipe L1 is supplied as the first gas to the hydrogen sulfide removal device 40 via the pipe L2, while on the other hand, as the second gas via the pipe L3. The sulfuric acid production apparatus 50 is supplied.

(Step (III))
Step (III) is a step of removing hydrogen sulfide contained in the first gas in the hydrogen sulfide removing device 40. By having the step (III), hydrogen sulfide contained in the first gas can be removed, and a target gas having a hydrogen sulfide-containing concentration reduced to the ppm order can be obtained.
Hydrogen sulfide is removed from the first gas supplied to the hydrogen sulfide removing device 40 via the pipe L2, and is taken out as a target gas to the outside via the pipe L4.

Step (III) in this embodiment includes a step using an amine absorption method. The hydrogen sulfide removed by the amine absorption method is supplied to the sulfuric acid production apparatus 50 through the pipe L5. In place of the amine absorption method, a chemical absorption oxidation regeneration method using a solution in which a small amount of picric acid is dissolved in an aqueous sodium carbonate solution, caustic soda, or an aqueous ammoniacal solution can be used.
When using the chemical absorption oxidation regeneration method, the hydrogen sulfide-containing concentration in the first gas is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less.
When the chemical absorption oxidation regeneration method is used as the step (III), the removed hydrogen sulfide may be recovered as a single sulfur slurry, and may be recovered as single sulfur after dehydration. Moreover, it can use as a raw material of the sulfuric acid in process (IV) by supplying to the sulfuric acid manufacturing apparatus 50 as a sulfur dioxide through a separate combustion process.

(Process (IV))
Step (IV) is a step of producing sulfuric acid using the second gas in the sulfuric acid production apparatus 50. By having the step (IV), hydrogen sulfide contained in the raw material gas can be taken out to the outside not as simple sulfur but as sulfuric acid product with high added value.
The second gas separated by the hydrogen sulfide separation device 30 is supplied to the sulfuric acid production device 50 via the pipe L3, and is taken out as the sulfuric acid product or the like via the pipe L8.
In the step (IV), the hydrocarbon contained in the second gas can be used as the fuel, so that the use of the fuel supplied from the outside can be saved.
As a raw material of the step (IV), hydrogen sulfide removed in the step (III) can be used in addition to the second gas.

In the step (IV), when the hydrocarbon in the sulfuric acid production apparatus 50 is insufficient, a part of the raw material gas can be further used. Thereby, the fuel supply from the outside in process (IV) becomes unnecessary. A part of the source gas is supplied to the sulfuric acid production apparatus 50 through the pipe L7.
In addition, when the raw material for sulfuric acid is insufficient, a sulfur component such as hydrogen sulfide can be directly supplied to the sulfuric acid production apparatus 50. Therefore, the hydrogen sulfide removal method of this embodiment allows more sulfuric acid products and the like to be externally provided. It can be taken out and the sulfur component can be utilized more effectively.
Further, since the process (IV) produces a large amount of heat, further energy saving can be achieved by using this heat for the amine regeneration tower 402 in the amine absorption method of the process (III).

The method for removing hydrogen sulfide in the present invention is a combination of step (II) and step (IV). Step (I) and step (III) can be arbitrarily combined with step (II) and step (IV). For example, only step (I) may be combined with step (II) and step (IV), or only step (III) may be combined with step (II) and step (IV).
From the viewpoint of obtaining a target gas with a reduced concentration of hydrogen sulfide and producing more sulfuric acid products and the like, the hydrogen sulfide removal method of the present invention preferably includes all of steps (I) to (IV).

As described above, according to the hydrogen sulfide removal system 1 of the present embodiment, the raw material supply source 10 that supplies the raw material gas to the hydrogen sulfide separation device 30, and the organic sulfur component contained in the raw material gas in advance is converted to hydrogen sulfide. The hydrogen sulfide separator for separating the pretreatment device 20 into a first gas having a hydrogen sulfide-containing concentration lower than that of the source gas and a second gas having a hydrogen sulfide-containing concentration higher than that of the source gas 30, a hydrogen sulfide removal device 40 provided on the secondary side of the hydrogen sulfide separation device 30 and capable of removing hydrogen sulfide contained in the first gas, and a sulfuric acid production device 50 for producing sulfuric acid using a sulfur component as a raw material. And an exhaust gas treatment device 60 for treating the exhaust gas discharged from the sulfuric acid production device 50, a pipe L0 for introducing the raw material gas, and a hydrogen sulfide separation device for treating the raw material gas treated by the pretreatment device 20 A pipe L1 for supplying to the pipe 30; a pipe L2 for supplying the first gas to the hydrogen sulfide removing apparatus 40; a pipe L3 for supplying the second gas to the sulfuric acid production apparatus 50; A pipe L4 for deriving the target gas, a pipe L5 for supplying hydrogen sulfide removed by the hydrogen sulfide removing apparatus 40 to the sulfuric acid production apparatus 50, and a pipe for supplying heat obtained by the sulfuric acid production apparatus 50 to the hydrogen sulfide removal apparatus 40 L6, a pipe L7 branched from the pipe L0 at the branch 101 and supplying a part of the raw material gas to the sulfuric acid production apparatus 50, a pipe L8 for deriving a sulfuric acid product derived from the sulfuric acid production apparatus 50, and sulfuric acid production It has a configuration provided with a pipe L9 for leading exhaust gas discharged from the device 50.
Therefore, when removing hydrogen sulfide contained in the raw material gas, energy saving can be achieved and the sulfur component can be effectively used.

Further, according to the method for removing hydrogen sulfide of the present embodiment, (I) the step of treating the source gas, and (II) the source gas containing hydrocarbon and hydrogen sulfide has a hydrogen sulfide-containing concentration higher than that of the source gas. A step of separating into a low first gas and a second gas having a higher hydrogen sulfide content concentration than the source gas, (III) a step of removing hydrogen sulfide contained in the first gas, and (IV) And a step of producing sulfuric acid using the second gas.
Therefore, when removing hydrogen sulfide contained in the raw material gas, energy saving can be achieved and the sulfur component can be effectively used.

As another embodiment to which the present invention is applied, the configuration of a hydrogen sulfide removal system 2 is shown in FIG.
FIG. 2 is a system diagram showing a configuration of a hydrogen sulfide removal system 2 which is another embodiment to which the present invention is applied. In the hydrogen sulfide removal system 2, the second gas separated by the hydrogen sulfide separation device 30 is supplied to the sulfur recovery device 510 of the sulfuric acid production device 50 ′ via the pipe L3. The sulfur recovery device 510 is not particularly limited, and a known device for recovering sulfur can be used. Various types of sulfur recovery apparatuses 510 have been proposed. However, in consideration of equipment size and the like, an apparatus using a Claus method in which hydrogen sulfide is burned in a state where oxygen is limited is preferable. Sulfur recovered by the sulfur recovery device 510 contains carbon fine particles derived from hydrocarbons contained in the second gas. When the combustible component in the second gas is less than 5%, the raw material gas can be supplied as fuel to the sulfur recovery device 510 via the pipe L7 ′. The pipe L7 ′ is provided with an on-off valve 90 that opens and closes according to the concentration of the combustible component in the second gas. The pipe L7 ′ branches from the pipe L7 at the branch 107, and merges with the pipe L3 at the branch.

The hydrogen sulfide removed by the hydrogen sulfide removing device 40 may be supplied to the combustion device 501 ′ via the pipe L5a, the branch 111, and the pipe L5b, and the pipe L5a and the pipe L3 merge at the branch 103 ′. The sulfur recovery device 510 may be supplied together with the gas. By appropriately opening and closing the check valve 80 provided in the pipe L5a and the check valve 80 ′ provided in the pipe L5b, the route of hydrogen sulfide is determined. Sulfur recovered by the sulfur recovery device 510 is supplied to the combustion device 501 ′ via the pipe L59. Sulfur supplied to the combustion device 501 ′ is a mixture of simple sulfur and carbon fine particles, so that the amount of heat is high, and moisture generated in the combustion device 501 ′ can be reduced, and the load on the dehydration device 503 is reduced. be able to. For this reason, it is preferable that the hydrogen sulfide removed by the hydrogen sulfide removal device 40 joins the pipe L3 at the branch 103 ′ and is supplied to the sulfur recovery device 510 together with the second gas.
Although it is possible to supply the raw material gas to the combustion device 501 ′ via the pipe L7, in this embodiment, a sufficient amount of heat is generated by combustion of the mixture of sulfur and carbon fine particles supplied from the sulfur recovery device 510. It is possible to obtain. For this reason, the raw material gas is not supplied to the combustion device 501 ′ via the pipe L7 except in an unsteady state such as at startup.

This embodiment is particularly effective when the ratio of hydrogen sulfide to the total amount of hydrogen sulfide and carbon dioxide contained in the raw material gas is relatively low at less than 10%.
The combustion gas containing sulfur dioxide obtained by the combustion device 501 ′ is supplied to the dehydration device 503 via the pipe L51 and the heat recovery device 502.
Other configurations are the same as those of the first embodiment, but in this embodiment, water caused by hydrocarbons such as methane and hydrogen derived from hydrogen sulfide is not generated during steady operation, so Little water is produced in the reaction process. For this reason, after the concentrated sulfuric acid generated in the absorption tower 506 is supplied from the pipe L8 to the dehydrator 503 via the branch 106, the pipe L57, and the branch 109, the water is contained in the combustion gas. By returning the diluted sulfuric acid to the absorption tower 506 with L58b, a sulfuric acid product or the like can be obtained. At this time, water may be supplied from the water supply means 11 to the concentrated sulfuric acid dilution device 507 via the pipe L12 ′.

Since the other configuration of the hydrogen sulfide removal system 2 is the same as that of the hydrogen sulfide removal system 1, description thereof is omitted.

FIG. 3 is a system diagram showing a configuration of an embodiment of a conventional hydrogen sulfide removal system 3. In the conventional hydrogen sulfide removal system 3, the raw material gas is supplied to the pretreatment device via the pipe L0, and the pretreated gas is supplied to the hydrogen sulfide removal device 40 ′ via the pipe L1. The hydrogen sulfide removal device 40 ′ is connected to the sulfur recovery device 300 via the pipe L5, and the hydrogen sulfide obtained by the hydrogen sulfide removal device 40 ′ is supplied to the sulfur recovery device 300 via the pipe L5.
In the sulfur recovery apparatus 300, air is supplied from the air supply source 200 through the pipe L7, single sulfur is led out through the pipe L8, and exhaust gas is led out through the pipe L9.
In the case of such a conventional hydrogen sulfide removal system 3, the produced single sulfur has a low commercial value due to overproduction. In addition, a combustion apparatus that burns solid sulfur obtained in solid form for the production of sulfuric acid has a problem that the operation of the apparatus is complicated.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.
For example, in the hydrogen sulfide removal system 1 described above, an example in which the pipe L7 is provided on the primary side of the pretreatment device 20 has been described.
However, it is not limited to this embodiment, and the pipe L7 may be provided on the secondary side of the pretreatment device 20, and after the mercaptan contained in the raw material gas is hydrogenated to hydrogen sulfide, the pipe L7 is Alternatively, the sulfuric acid production apparatus 50 may be supplied.
Further, the pretreatment device 20 may not be present in the hydrogen sulfide removal system.

By using the hydrogen sulfide removal system and the hydrogen sulfide removal method of the present invention, hydrogen sulfide contained in the raw material gas can be removed, and a purified target gas can be produced. Further, it is possible to produce a sulfuric acid product with high added value without discharging excessive production of simple sulfur. Further, by using the hydrocarbon contained in the raw material gas as the fuel for the sulfuric acid production process, sulfuric acid can be produced even if the concentration of removed hydrogen sulfide is low. In addition, as compared with the case of producing sulfuric acid by burning only sulfur, there is an advantage that the change in the operating condition of the plant becomes gentle by simultaneously treating the carbon dioxide gas in the process of hydrogen sulfide treatment. In addition, since the low-temperature exhaust heat generated in the sulfuric acid production process can be used effectively, even in small-scale oil and gas fields, it is easy to remove hydrogen sulfide in the production area, and energy saving can be achieved.

DESCRIPTION OF SYMBOLS 1, 2 Hydrogen sulfide removal system 3 Conventional hydrogen sulfide removal system 10 Raw material supply source 20 Pretreatment apparatus 30 Hydrogen sulfide separation apparatus 40, 40 'Hydrogen sulfide removal apparatus 50, 50' Sulfuric acid production apparatus 60 Exhaust gas treatment apparatus 70, 90 Opening and closing Valve 80, 80 ′ Check valve 11 Water supply means 200 Air supply source 300, 510 Sulfur recovery device 401 Amine absorption tower 402 Amine regeneration tower 403 Compressor 501, 501 ′ Combustion device 502, 505 Heat recovery device 503 Dehydration device 504 Conversion device 506 Absorption tower 507 Concentrated sulfuric acid dilution apparatus 101, 102, 103, 103 ′, 104, 105, 106, 107, 108, 109, 110, 111, 112 Branching (merging)
L0, L1, L2, L3, L4, L5, L5a, L5b, L6, L7, L7 ′, L8, L9, L12, L12 ′, L41, L42, L43, L51, L52, L53, L54, L55, L56, L57, L58, L58a, L58b, L59 Piping

Claims (8)

Sulfurization for separating a raw material gas containing hydrocarbon and hydrogen sulfide into a first gas having a hydrogen sulfide-containing concentration lower than that of the raw material gas and a second gas having a hydrogen sulfide-containing concentration higher than that of the raw material gas A hydrogen separator,
A hydrogen sulfide removal system comprising: a sulfuric acid production apparatus that produces sulfuric acid using the second gas. The hydrogen sulfide separation device further comprising a hydrogen sulfide removal device for removing hydrogen sulfide contained in the first gas on a secondary side of the hydrogen sulfide separation device, wherein the hydrogen sulfide separation device uses a separation membrane. 2. The hydrogen sulfide removal system according to 1. The hydrogen sulfide removal system according to claim 1 or 2, further comprising a pipe capable of supplying the raw material gas to the sulfuric acid production apparatus on the primary side of the hydrogen sulfide separation apparatus. The hydrogen sulfide removal system according to any one of claims 1 to 3, further comprising a pretreatment device capable of treating the source gas on a primary side of the hydrogen sulfide separation device. Separating a source gas containing hydrocarbon and hydrogen sulfide into a first gas having a hydrogen sulfide-containing concentration lower than that of the source gas and a second gas having a hydrogen sulfide-containing concentration higher than that of the source gas; ,
And a step of producing sulfuric acid by using the second gas. The method for removing hydrogen sulfide according to claim 5, further comprising a step of removing hydrogen sulfide contained in the first gas using a separation membrane. The method for removing hydrogen sulfide according to claim 5 or 6, further comprising a step of using the raw material gas when hydrocarbons are insufficient in the step of producing the sulfuric acid. The method for removing hydrogen sulfide according to any one of claims 5 to 7, further comprising a step of treating the source gas before the step of separating hydrogen sulfide.

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