JP7616991B2 - Purified gas production method and purified gas production apparatus - Google Patents

Description

The present invention relates to a method and an apparatus for producing purified gas obtained by refining crude gas derived from waste.

There is a known technology for gasifying various types of waste, such as industrial waste and general waste, through pyrolysis (see Patent Document 1, etc.). According to this method, waste is pyrolyzed to obtain synthesis gas containing large amounts of carbon monoxide and hydrogen. Gases derived from waste, such as synthesis gas, can be used for various purposes. For example, attempts have been made to convert them into valuable products, such as ethanol, using microbial catalysts or metal catalysts.

Waste contains a variety of components, and the gas obtained from waste also contains many impurities. Therefore, gas derived from waste needs to be purified by removing the impurities. A widely known method for removing impurities is the use of a scrubber. The impurities contained in waste-derived gas include water-soluble impurities such as hydrogen chloride and hydrogen sulfide, and oil-soluble impurities such as BTEX. As a method for removing these impurities using a scrubber, for example, as disclosed in Patent Document 1, a method is known in which water-soluble impurities are removed by washing the gas with water spray in a precooler, and oil-soluble impurities are removed by spraying washing oil in a light oil scrubber.

JP 2007-45857 A

However, according to the method disclosed in Patent Document 1, water-soluble impurities and oil-soluble impurities are removed in separate washing towers, requiring large-scale equipment.

Therefore, the objective of the present invention is to provide a purified gas production apparatus and a purified gas production method that can efficiently remove water-soluble impurities and oil-soluble impurities using a scrubber while simplifying the equipment.

[1] A method for producing a purified gas, comprising the steps of: removing at least a portion of water-soluble impurities and oil-soluble impurities from a raw gas derived from waste material, the water-soluble impurities and the oil-soluble impurities being contained therein, using a scrubber;
a cleaning solution containing water and oily substances is contacted with the crude gas in the scrubber to remove at least a portion of the water-soluble impurities and the oil-soluble impurities from the crude gas; and a proportion of the oily substances in the cleaning solution is 5% by volume or more and 95% by volume or less.
[2] The method for producing a refined gas according to the above [1], further comprising adjusting the ratio of the oily substance in the cleaning solution.
[3] The method for producing a refined gas according to the above [1] or [2], wherein the oily substance includes oil-soluble impurities that have been removed from the crude gas and mixed into the cleaning liquid.
[4] The method for producing a refined gas according to any one of the above [1] to [3], wherein the crude gas is a synthesis gas containing the water-soluble impurities and the oil-soluble impurities.
[5] The scrubber includes a storage section for storing the water and the oily substance,
The method for producing a refined gas according to any one of the above [1] to [4], wherein the water and the oily substance are supplied from the reservoir as a wash liquid to be brought into contact with the crude gas.
[6] The scrubber includes a storage section for storing the water and the oily substance,
The method for producing a refined gas according to any one of the above [1] to [5], wherein the water and the oily substances are independently recovered from the reservoir, and the recovered water and the oily substances are mixed together to form the cleaning liquid and contacted with the crude gas.
[7] The scrubber includes a storage section for storing a cleaning liquid containing the water and the oily substance,
The method for producing a purified gas according to any one of the above [1] to [4], wherein the crude gas is brought into contact with the cleaning liquid by passing the crude gas through the cleaning liquid stored in the storage section.
[8] The method for producing a refined gas according to any one of [5] to [7] above, wherein a portion of the water or oily substances stored in the storage section is removed to adjust the ratio of the oily substances in the cleaning liquid.
[9] A method for producing a purified gas, comprising the steps of: removing at least a portion of water-soluble impurities and oil-soluble impurities from a raw gas containing water-soluble impurities and oil-soluble impurities using a scrubber to produce a purified gas,
a washing liquid containing water and oily substances is contacted with the crude gas in the scrubber to remove at least a portion of the water-soluble impurities and oil-soluble impurities from the crude gas; and a ratio of the oily substances in the washing liquid is adjusted.
[10] A refined gas production apparatus for producing a refined gas by removing at least a portion of water-soluble impurities and oil-soluble impurities from a crude gas containing water-soluble impurities and oil-soluble impurities,
a scrubber that contacts the crude gas with a wash liquid containing water and oily substances to remove at least a portion of the water-soluble impurities and oil-soluble impurities from the crude gas;
an adjusting mechanism capable of adjusting the ratio of the oily substance in the cleaning liquid;
A refined gas production apparatus comprising:
[11] The refined gas production apparatus according to [10] above, wherein the ratio of the oily substance in the cleaning liquid is 5 volume % or more and 95 volume % or less.
[12] The refined gas production apparatus according to the above [10] or [11], wherein the scrubber has a storage section for storing the water and the oily substances, and is provided with a supply passage for supplying the water and the oily substances from the storage section so as to contact the crude gas as the cleaning liquid.
[13] The scrubber has a storage section for storing the water and the oily substance, and the adjustment mechanism has first and second recovery paths,
The refined gas production apparatus according to the above-mentioned [10] or [11], wherein each of the first and second recovery paths independently recovers the water and oily substances in the storage section, and the recovered water and oily substances are mixed to form the cleaning liquid, which is then contacted with the crude gas.
[14] The scrubber has a storage section for storing a cleaning liquid containing the water and the oily substance,
The refined gas production apparatus according to the above [10] or [11], further comprising an introduction passage for introducing the crude gas into the cleaning liquid stored in the storage section.
[15] The refined gas production apparatus according to any one of [10] to [14] above, wherein the adjustment mechanism is a removal device that removes a portion of the water or oily substance stored in the storage section.
[16] A refined gas production apparatus for producing a refined gas by removing at least a portion of water-soluble impurities and oil-soluble impurities from a crude gas containing water-soluble impurities and oil-soluble impurities,
a scrubber that contacts the crude gas with a wash liquid containing water and an oily substance to remove at least a portion of the water-soluble impurities and the oil-soluble impurities from the crude gas;
A refined gas production apparatus, wherein the ratio of the oily substance in the cleaning liquid is 5 volume % or more and 95 volume % or less.

The present invention makes it possible to efficiently remove water-soluble and oil-soluble impurities using a scrubber while simplifying the equipment.

1 is a schematic diagram showing the overall configuration of a refined gas production apparatus according to the present invention. 1 is a schematic diagram showing details of a refined gas production apparatus according to a first embodiment of the present invention; FIG. 5 is a schematic diagram showing details of a refined gas production apparatus according to a second embodiment of the present invention. FIG. 5 is a schematic diagram showing details of a refined gas production apparatus according to a third embodiment of the present invention.

Next, the present invention will be described using an embodiment.
1 shows a purified gas production apparatus according to a first embodiment of the present invention. The purified gas production apparatus 10 includes a crude gas production facility 11 and a scrubber 12. The crude gas production facility 11 is a facility for producing a crude gas G1 which is a waste-derived gas. The crude gas G1 produced in the crude gas production facility 11 is introduced into the scrubber 12. The scrubber 12 purifies the introduced crude gas G1 to obtain a purified gas G2.

The raw gas generation facility 11 is equipped with a device for burning and pyrolyzing waste, and is equipped with, for example, one or more combustion furnaces, pyrolysis furnaces, reforming furnaces, heating furnaces, etc. The waste may be industrial waste or general waste such as household garbage, and is not particularly limited as long as it is a combustible material, such as tires, biomass, wood chips, plastic, paper, food waste, etc. The raw gas G1 is a waste-derived gas obtained by burning and pyrolyzing the waste in the raw gas generation facility 11.

The crude gas G1 contains at least either carbon monoxide or carbon dioxide, and is preferably a synthesis gas. The synthesis gas constituting the crude gas G1 contains impurities such as water-soluble impurities and oil-soluble impurities as described below, and is therefore referred to as a "crude synthesis gas" here. The crude synthesis gas may be obtained by, for example, pyrolysis of waste in a pyrolysis furnace, or may be obtained by pyrolyzing waste in a pyrolysis furnace and then further reducing the carbon content in a reforming furnace. In addition, the crude synthesis gas may be subjected to a degassing process in a heating furnace or the like before pyrolysis in the pyrolysis furnace.
The crude synthesis gas contains carbon monoxide and hydrogen, and usually also contains carbon dioxide. The crude synthesis gas generally further contains nitrogen, oxygen, and water as gas components. Specifically, the crude synthesis gas contains 15 to 45 vol% carbon monoxide, 10 to 50 vol% hydrogen, and 2 to 30 vol% carbon dioxide, and may further contain about 25 to 67 vol% nitrogen, 0.5 to 20 vol% oxygen, and 5 to 40 vol% water.

In addition to the above gas components, the crude gas G1 also contains water-soluble impurities and oil-soluble impurities. Water-soluble impurities are substances that are soluble in the water contained in the cleaning solution, and examples of such impurities include acidic gases such as hydrogen sulfide, hydrogen chloride, and hydrocyanic acid, basic gases such as ammonia, and oxides such as NOx and SOx. Therefore, these water-soluble impurities dissolve when they come into contact with the cleaning water, as described below. However, water-soluble impurities may also dissolve in oil-based substances, which will be described later.

Oil-soluble impurities are organic substances that can dissolve in the oily substances described below. Examples of oil-soluble impurities include aromatic ring-containing organic substances such as BTEX (benzene, toluene, ethylbenzene, xylene), naphthalene, 1-naphthol, 2-naphthol, indene, benzonitrile, acenaphthylene, 2'-acetonaphthone, 1-(2-naphthyl)ethanol, 1-acenaphthenol, 1,2-acenaphthylenedione, benzo[de]isochromene-1(3H)-one, and 1,8-naphthalic anhydride, and aliphatic organic substances such as 4-formylmorpholine. The crude gas may also contain solid impurities such as soot and tar that are not soluble in water or the oily substances described below.

In the scrubber 12, a washing liquid is brought into contact with the crude gas G1, and at least a portion of the water-soluble impurities and oil-soluble impurities are removed from the crude gas G1, to obtain a purified gas G2. Here, a washing liquid containing water and an oily substance is used as the washing liquid. By containing water and an oily substance, the washing liquid dissolves the water-soluble impurities and oil-soluble impurities contained in the crude gas into the water and the oily substance, respectively, and both the water-soluble impurities and the oil-soluble impurities can be efficiently removed from the crude gas.
The oily substance is an organic substance that is in a liquid state in the cleaning liquid when the cleaning liquid comes into contact with the exhaust gas G1. As described later, oil-soluble impurities are preferably used as the oily substance. Thus, examples of the oily substance include the same oil-soluble impurities as those described above, but are preferably aromatic ring-containing organic substances such as BTEX (benzene, toluene, ethylbenzene, xylene), naphthalene, 1-naphthol, 2-naphthol, indene, benzonitrile, acenaphthylene, 2'-acetonaphthone, 1-(2-naphthyl)ethanol, 1-acenaphthenol, 1,2-acenaphthylenedione, benzo[de]isochromene-1(3H)-one, and 1,8-naphthalic anhydride, and aliphatic organic substances such as 4-formylmorpholine.

The ratio of oily substances in the cleaning solution is 5% by volume or more and 95% by volume or less. If the ratio of oily substances is less than 5% by volume, oil-soluble impurities cannot be sufficiently removed from the raw gas. On the other hand, if the ratio exceeds 95% by volume, the ratio of water in the cleaning solution becomes small, and water-soluble impurities may not be sufficiently removed. Also, if the ratio exceeds 95% by volume, the oily substances will be more than necessary in the cleaning solution, and it will be difficult to attribute most or all of the oily substances to impurities.
From the viewpoint of removing oil-soluble impurities and water-soluble impurities in a well-balanced manner, the ratio of the oily substance in the cleaning solution is preferably 25% by volume or more and 75% by volume or less. From the viewpoint of removing oil-soluble impurities, the ratio is more preferably 30% by volume or more, and from the viewpoint of not using more oily substance than necessary, the ratio is more preferably 50% by volume or less.

The cleaning solution that comes into contact with the crude gas is composed mainly of water and oily substances, and the proportion of water in the cleaning solution is preferably, for example, 5% by volume or more and 95% by volume or more. When the proportion of water in the cleaning solution is 5% by volume or more, water-soluble impurities can be appropriately removed from the crude gas. Furthermore, when the proportion of water is 95% by volume or less, it becomes possible to contain a sufficient amount of oily substances in the cleaning solution. From the viewpoint of removing oil-soluble impurities and water-soluble impurities in a balanced manner, the proportion of water in the cleaning solution is preferably 25% by volume or more and 75% by volume or less, from the viewpoint of removing oil-soluble impurities, more preferably 70% by volume or less, and from the viewpoint of not using more oily substances than necessary, more preferably 50% by volume or more.

Here, the ratio of oily substances in the cleaning solution may be measured by collecting the cleaning solution, allowing the collected cleaning solution to separate into oil and water while maintaining its temperature, and measuring the ratio of the volume of the oil to the total volume of the cleaning solution. Therefore, the ratio of oily substances is the volume including impurities, etc., when impurities are dissolved in the oil. When the oil and water do not separate, they may be separated using an oil-water separator such as a centrifugal separator. The ratio of water in the cleaning solution may be measured by separating the water by distillation or the like, measuring the weight of the water, and calculating the volume from the weight.
The ratio of oily substances and water in the cleaning liquid may be measured by measuring the ratio of oily substances and water in the cleaning liquid when it comes into contact with the raw gas G1. Therefore, when measuring the ratio of oily substances, in an embodiment in which the cleaning liquid is circulated and brought into contact with the flue gas G1, such as in the scrubber of the present embodiment described later, the ratio of oily substances in the cleaning water may be measured by sampling the cleaning water immediately before it comes into contact with the flue gas G1, i.e., the cleaning water sprayed from the nozzle 15. In addition, in an embodiment in which the cleaning liquid is brought into contact with the flue gas G1 in a stored state, such as in the third embodiment described later, the stored cleaning liquid may be sampled and the ratio of oily substances may be measured.
It is advisable to collect samples from multiple points. For example, it is desirable that the collected amount of liquid at each point is 0.25% by volume or more of the cleaning liquid during the process. In addition, when collecting the stored cleaning liquid as a sample, it is advisable to thoroughly stir the cleaning liquid and then collect samples from multiple points as far apart as possible. Then, after mixing the collected liquid, the volume is confirmed using a measuring cylinder or a measuring flask, and the ratio of the volume to the cleaning liquid is calculated. In addition, as described above, if the oil and water do not separate, it is advisable to centrifuge the mixture in a centrifuge and reconfirm the volume of the oil from the total collected amount in the same manner. In this case, the centrifuge is operated at 5000 rpm or more for 1 minute or more.

The cleaning liquid removes water-soluble impurities and oil-soluble impurities by dissolving them in the water and oil-based substances contained in the cleaning liquid, respectively, and the cleaning liquid after contacting the crude gas contains the removed water-soluble impurities and oil-soluble impurities. Meanwhile, in this embodiment, for example, the cleaning liquid is circulated inside the scrubber, and is continuously used as the cleaning liquid even after contacting the crude gas. In addition, oil-soluble impurities include many types of substances, and also include substances that are highly soluble in oil-soluble impurities, and such substances can be beneficially used as the oil-based substances in the cleaning liquid.

Therefore, in the present invention, it is preferable that the oil-soluble impurities removed from the crude gas and mixed into the cleaning solution continue to be contained in the cleaning solution as they are and used as oily substances. In this way, when the oil-soluble impurities removed from the crude gas are used as the oily substance of the cleaning solution, the water-soluble impurities and oil-soluble impurities can be efficiently removed by the scrubber without adding more oily substances than necessary to the cleaning solution.

The oily substance may be composed solely of oil-soluble impurities obtained from the crude gas G1, but oily substances may be added to the cleaning solution separately in addition to the oil-soluble impurities obtained from the crude gas G1. For example, when the scrubber 12 starts operating, it is possible that the oil-soluble impurities are not sufficiently accumulated in the cleaning solution, and the proportion of oily substances in the cleaning solution described above does not reach or exceed the lower limit. Therefore, in such a case, the oily substance may be added to the cleaning solution.

The refined gas production apparatus 10 may be provided with an adjustment mechanism for adjusting the proportion of oily substances in the cleaning solution used in the scrubber 12. As described above, by setting the proportion of oily substances in the cleaning solution that is brought into contact with the crude gas within a certain range, oil-soluble impurities can be efficiently removed. Therefore, by appropriately adjusting the proportion of oily substances in the cleaning solution using the adjustment mechanism, oil-soluble impurities can be more efficiently removed. Furthermore, the adjustment mechanism typically adjusts the proportion of water in the cleaning solution as well as the proportion of oily substances in the cleaning solution. Details of the adjustment mechanism will be described later.

The purified gas G2 generated in the scrubber 12 contains, for example, at least either carbon monoxide or carbon dioxide, and is converted into an organic compound such as ethanol in a reactor (not shown) or the like. The purified gas G2 is preferably a synthetic gas, and is more preferably converted into an organic compound such as ethanol by either a gas-assimilating microorganism or a metal catalyst, and is even more preferably converted into an organic compound such as ethanol by a gas-assimilating microorganism. In the present invention, the gas-assimilating microorganism and the metal catalyst are less likely to be deactivated by the purified gas G2 by appropriately removing water-soluble impurities and oil-soluble impurities.
Before being converted into organic compounds in the reactor, the purified gas G2 may be further purified by various cleaning devices such as a dust removal device such as a bag filter, various adsorption filters such as an activated carbon filter, a denitrification reaction tower, a desulfurization reaction tower, etc., and then sent to the reactor (not shown).

Hereinafter, this embodiment will be described in more detail with reference to Figure 2. As shown in Figure 2, the scrubber 12 is a washing tower for washing the raw gas G1, and has a storage section 14 at its bottom and a nozzle 15 at its top. In addition, an inlet passage 13, a supply passage 16, a discharge passage 19, etc. are connected to the scrubber 12.

The water WT and the oily substance OL are stored in the storage section 14. The water WT and the oily substance OL stored in the storage section 14 are mixed by a stirring means (not shown) such as a stirring blade. The water WT and the oily substance OL stored in the storage section 14 constitute a cleaning liquid. The cleaning liquid stored in the storage section 14 usually contains impurities derived from the crude gas G1 in addition to the water WT and the oily substance OL.
The oily substance OL stored in the storage section 14 may be composed of oil-soluble impurities derived from the crude gas G1 as described above, but an oily substance may be added separately as appropriate at the start of operation, etc. Also, a certain amount of water WT may be stored in the storage section 14 from the start of operation. The nozzle 15 sprays a cleaning liquid into the inside of the scrubber 12 as described below.

The inlet passage 13 is a path for introducing the crude gas G1 into the scrubber 12, and the inlet 13A of the inlet passage 13 is provided, for example, above the liquid level of the water WT and oily substance OL (cleaning liquid) stored inside the scrubber 12.
The supply path 16 circulates the cleaning liquid in the scrubber 12 and supplies the cleaning liquid so as to contact the crude gas G1. Specifically, the supply path 16 sprays the water WT and oily substances OL stored in the storage section 14 downward from the nozzle 15 inside the scrubber 12 as cleaning liquid and contacts the crude gas G1. The water WT and oily substances OL (cleaning liquid) stored in the storage section 14 are mixed as described above, and are sprayed from the nozzle 15 in a mixed state. In addition, for example, a pump 18 is provided in the supply path 16, and the cleaning liquid is pressure-fed to the nozzle 15 by the pump 18. Then, the cleaning liquid WS is sprayed downward from the nozzle 15 inside the scrubber 12. The discharge path 19 is provided at the upper part of the scrubber 12 and discharges the refined gas G2.

The crude gas G1 introduced into the scrubber 12 from the inlet 13A rises while coming into contact with the cleaning solution WS sprayed from the nozzle 15. The crude gas G1 is brought into contact with the cleaning solution WS containing water WT and oily substances OL, whereby at least a portion of the water-soluble impurities and oil-soluble impurities contained in the crude gas G1 are removed. The gas from which these impurities have been removed is discharged as a purified gas G2 from the exhaust path 19. As described above, the proportion of the oily substances in the cleaning solution WS is within a predetermined range, and therefore the water-soluble impurities and oil-soluble impurities are efficiently removed from the crude gas G1.
Inside the scrubber 12, a contact area A where the cleaning solution WS sprayed from the nozzle 15 comes into contact with the crude gas G1 is formed between the nozzle 15 and a mixture (cleaning solution) of water WT and oily substance OL stored in the storage section 14 inside the scrubber 12. A porous body (not shown) or the like may be disposed in the contact area A to increase the contact area between the cleaning solution WS and the crude gas G1.

The cleaning solution WS sprayed from the nozzle 15 falls to the storage section 14 while contacting the crude gas G1, is stored in the storage section 14, and is used again as a cleaning solution. The oil-soluble impurities and water-soluble impurities removed from the crude gas G1 are dissolved in the cleaning solution WS (water or oily substance), etc., and fall together with the cleaning solution to the storage section 14, and are stored in the storage section 14. Here, as described above, it is preferable that at least a portion of the oil-soluble impurities directly constitute the oily substance in the cleaning solution.
Furthermore, the crude gas G1 also contains impurities other than oil-soluble impurities and water-soluble impurities (for example, solid impurities such as soot), but these impurities are also removed from the crude gas G1 by contacting with the cleaning solution WS sprayed from the nozzle 15, and fall into the storage section 14. Therefore, it is preferable that the storage section 14 stores solid impurities IP in addition to the oil-soluble substances, water, and water-soluble impurities as described above.

As described above, the cleaning liquid stored in the storage section 14 is sent to the nozzle 15 in a homogenized state in which the oily substance OL and the water WT are mixed together. Therefore, the proportion of the oily substance OL in the cleaning liquid stored in the storage section 14 is the same as the proportion of the oily substance in the cleaning liquid WS sprayed from the nozzle 15. Therefore, in this embodiment, the proportion of the oily substance in the cleaning liquid WS sprayed from the nozzle 15 (i.e., the cleaning liquid WS that comes into contact with the crude gas G1) can be adjusted by adjusting the proportion of the oily substance OL in the cleaning liquid stored in the storage section 14 using the adjustment mechanism. Similarly, the proportion of water in the cleaning liquid WS sprayed from the nozzle 15 can also be adjusted.

The temperature of the cleaning liquid WS in the scrubber 12 is not particularly limited, but may be, for example, about 0 to 80° C. From the viewpoint of not needing temperature adjustment and the removal efficiency by the cleaning liquid WS, the temperature of the cleaning liquid in the scrubber 12 is preferably near room temperature, specifically about 10 to 50° C. In addition, in the present specification, the temperature of the cleaning liquid WS refers to the temperature of the cleaning liquid WS measured immediately before contact, that is, the temperature of the cleaning water WS sprayed from the nozzle 15, when the cleaning liquid WS is circulated and brought into contact with the exhaust gas G1 as in the present embodiment. In addition, when the cleaning liquid WS is brought into contact with the exhaust gas G1 in a stored state as in the third embodiment described later, the temperature of the cleaning liquid stored in the storage section may be measured.
The temperature of the cleaning solution WS may be controlled by a temperature control device, which may be attached, for example, to the supply path 16 to adjust the temperature of the cleaning solution passing through the inside of the supply path 16, or may be provided on the outer periphery of the scrubber to adjust the temperature of the cleaning solution stored in the storage section 14 of the scrubber.

The temperature of the crude gas G1 introduced into the scrubber 12 is not particularly limited, but is, for example, 0 to 400° C. The crude gas G1 is heated to a high temperature by pyrolysis, combustion, etc. in the crude gas generation equipment 11 (see FIG. 1). Therefore, if the crude gas generated in the crude gas generation equipment 11 is sent to the scrubber 12 without being sufficiently cooled, it is introduced into the scrubber 12 at a high temperature. On the other hand, if it is cooled in advance in the crude gas generation equipment 11, it may be introduced into the scrubber 12 at around room temperature. Therefore, the temperature range of the crude gas G1 is preferably as described above. Note that, if the temperature of the crude gas G1 introduced into the scrubber 12 is higher than the temperature of the cleaning liquid, the crude gas G1 is cooled by contacting with the cleaning liquid in the scrubber 12.
The temperature of the crude gas G1 is preferably 0 to 100° C., and more preferably 20 to 80° C., from the viewpoint of preventing the cleaning liquid from evaporating in the scrubber 12. The temperature of the crude gas G1 means the temperature of the crude gas G1 immediately before it is contacted with the cleaning liquid, and may be measured at the inlet 13A of the introduction path 13A.

In this embodiment, a removal device 20 connected to the scrubber 12 via a circulation path 21 is provided as an adjustment mechanism. The removal device 20 is a device that separates and removes a portion of the water WT or oily substances OL from the cleaning liquid stored in the storage section 14, but it is preferable to separate and remove a portion of the oily substances OL. In this embodiment, by continuously cleaning the raw gas G1, the oily substances OL derived from oil-soluble impurities accumulate in the storage section 14. Therefore, by separating and removing a portion of the oily substances OL, it is possible to prevent the oily substances OL from being contained in the cleaning liquid more than necessary.

A portion of the cleaning liquid in the storage section 14 is sent to the removal device 20 via the circulation path 21. Note that the cleaning liquid in the storage section 14 (i.e., the cleaning liquid sent to the removal device 20) is a mixture of water WT and oily substance OL as described above, and the mixture may contain impurities such as water-soluble impurities and solid impurities.

The removal device 20 separates the cleaning liquid sent from the storage section 14 into water and oily substances by known means, and returns one of the separated water and oily substances to the storage section 14 via the circulation path 21. As a result, one of the water WT and the oily substances OL is partially removed from the storage section 14, and the proportion of the oily substances OL in the storage section 14 is adjusted, and further, the proportion of the water WT is also adjusted to the predetermined proportion described above. In this way, the removal device 20 is used as the adjustment mechanism described above.

As the removal device 20, for example, a known oil-water separation device may be used. As the oil-water separation device, there is no particular limitation, but a permeable membrane type, a centrifugal separation type, etc. may be used. The removal device 20 may also separate water and oily substances by a distillation method or the like, for example by distilling off water and returning the distilled water to the scrubber 12 via the circulation path 21. The water or oily substances may also be distilled off using a dryer such as a CD dryer.

Furthermore, as described above, the cleaning liquid sent from the storage section 14 to the removal device 20 contains impurities such as water-soluble impurities and solid impurities IP, and it is preferable to remove the impurities in the removal device 20. The removal of the impurities is not particularly limited, but for example, the water may be distilled off and separated as described above, so that the various impurities are separated and removed from the water together with the oily substance OL, or the various impurities may be separated and removed from the water together with the oily substance using an oil-water separator or the like.

Also, for example, a filtration device may be provided in the upstream of the oil-water separation device. Examples of the filtration device include a filtration device that removes solid impurities, and a filtration device that is equipped with an ionic adsorbent and removes water-soluble impurities. Removing impurities such as solid impurities and water-soluble impurities using the removal device 20 can prevent impurities from accumulating in the cleaning liquid, so that the scrubber 12 can be operated continuously for a long period of time. Also, the removal device 20 may be a separation device that utilizes phase separation, and solid impurities may be separated using decantation.
In addition, in the removal device 20, it is not necessary to strictly separate water and oily substances. For example, when the separated water is returned to the scrubber 12, it is sufficient to remove the oily substances so that the proportion of water after separation is increased compared to before separation, and the water after separation may contain oily substances.

The ratio of oily substances or the ratio of oily substances and water in the cleaning liquid stored in the storage unit 14 or the cleaning liquid sprayed from the nozzle may be appropriately detected, and the ratio of oily substances or the ratio of oily substances and water in the cleaning liquid may be adjusted by the removal device 20 (adjustment mechanism) according to the detection result. However, the adjustment of the ratio of oily substances or the ratio of oily substances and water is not limited to the removal device 20 (adjustment mechanism), and may be performed by adding water or oily substances to the storage unit 14, etc.
The ratio of the oily substance, or the ratio of the oily substance and water, may be detected, for example, by sampling the cleaning liquid stored in the storage section 14 or the cleaning liquid sprayed from the nozzle at predetermined time intervals. The ratio of the oily substance may be detected by detecting the volume of the oily substance by oil-liquid separation as described above, or may be detected by FT-IR, gas chromatography, or the like. When detecting by gas chromatography, it is preferable to detect based on a calibration curve of a representative substance identified in advance. Moreover, the ratio of water may be detected by separating water from the cleaning liquid and measuring the volume.

The refined gas production apparatus may also include a detection device (not shown) that detects the proportion of oily substances or the proportion of oily substances and water in the cleaning liquid, and a control unit (not shown) that controls the detection device and the removal device. When the detection device and control unit are included, the detection results detected by the detection device are transmitted to the control unit, and in response to the detection results, the removal device 20 (adjustment mechanism) may be controlled by the control unit so that the proportion of oily substances or the proportion of oily substances and water in the cleaning liquid falls within the above-mentioned predetermined range.

As described above, according to the present embodiment, by making the cleaning liquid contain not only water but also oily substances and adjusting the content ratio of the oily substances within a predetermined range, it is possible to appropriately remove both water-soluble impurities and oil-soluble impurities from the crude gas G1 in one scrubber. In addition, the content ratio of the oily substances can be adjusted within a predetermined range by the adjustment mechanism. Therefore, it is possible to efficiently remove both water-soluble impurities and oil-soluble impurities with simple equipment.
Furthermore, the removed oil-soluble impurities can be used as oil-based substances as they are, so the amount of organic compounds input during cleaning can be minimized, enabling gas purification with a low environmental impact.

Second Embodiment
Next, a second embodiment of the present invention will be described. Differences between the first embodiment and the second embodiment will be described below. In the first embodiment described above, the water and the oily substance stored in the storage section are circulated in a mixed state and used as a cleaning liquid, but in this embodiment, the water and the oily substance are phase-separated in the storage section, and the phase-separated water and the oily substance are independently recovered, and after recovery, they are mixed and used as a cleaning liquid.

Specifically, as shown in Fig. 3, the scrubber 32 in this embodiment is provided with first and second recovery paths 36A, 36B as supply paths for supplying the cleaning liquid from the storage section 34 to contact the raw gas G1. In addition, in the storage section 34 inside the scrubber 32, the water WT and the oily substances OL are phase-separated, for example, by being left to stand. The inlets 36C, 36D of the first and second recovery paths 36A, 36B are arranged to face the phase-separated water WT and oily substances OL, and are joined on the delivery side and connected to the nozzle 35.
Therefore, the water WT and the oily substance OL are independently recovered through the first and second recovery paths 36A and 36B, respectively, and are mixed and sprayed from the nozzle 35 as the cleaning liquid WS, which comes into contact with the crude gas G1 introduced from the introduction path 33 in the contact area A. As a result, the crude gas G1 is purified, and the purified gas G2 is discharged from the exhaust gas 39. On the other hand, the cleaning liquid WS is mixed with the water-soluble impurities and oil-soluble impurities contained in the crude gas G1, and is stored in the storage section 34. At least a portion of the oil-soluble impurities is used as it is in the cleaning liquid as the oily substance OL.
It is preferable that pumps 38A, 38B are attached to the first and second recovery paths 36A, 36B, respectively, and that the water WT and the oily substance OL are pumped by the pumps 38A, 38B, respectively.

In this manner, in this embodiment, the water WT and the oily substances OL are each recovered via separate recovery paths 36A, 36B, so that the recovery amounts can be adjusted independently. Therefore, by appropriately adjusting the recovery amounts of the water WT and the oily substances OL, the proportion of the oily substances OL in the cleaning liquid WS that comes into contact with the crude gas G1, and further the amount of water WT in the cleaning liquid WS, can be adjusted. That is, in this embodiment, the first and second recovery paths 36A, 36B function as an adjustment mechanism that adjusts the proportion of the oily substances OL in the cleaning liquid, and further the proportion of the water WT.

In the storage section 34, the water WT and the oily substance OL usually form an aqueous layer 34A and an oily substance layer 34B, respectively, as shown in Fig. 3, and the oily substance layer 34B is disposed above the aqueous layer 34A. When the amount of water and oily substance stored in the storage section 34 changes, the height position of the oily substance layer 34B also changes. Therefore, the inlet 36D of the second recovery passage 36B for recovering the oily substance may be designed so that its height position can be changed according to the height position of the oily substance layer 34B. Of course, the height position of the inlet 36C of the recovery passage 36A for recovering water may also be designed so that it can be changed.
Furthermore, the first and second recovery paths 36A, 36B do not need to recover water WT and oily substances OL strictly separately, and other components may be contained as long as the ratio of oily substances, or the ratio of oily substances and water, in the cleaning solution WS can be changed by adjusting the recovery amounts in the first and second recovery paths 36A, 36B, respectively.

Also in this embodiment, it is preferable to provide the removal device 40. However, as described above, in this embodiment, the ratio of the oily substance and further the ratio of the water in the cleaning liquid can be adjusted by the recovery paths 36A and 36B, so there is no need to adjust the ratio of the oily substance and the water in the cleaning liquid using the removal device 40. On the other hand, the cleaning liquid (water WT and oily substance OL) stored in the storage section 34 contains impurities such as solid impurities and water-soluble impurities, so it is preferable to remove these impurities.
Therefore, the water WT stored in the storage unit 34 is sent to the removal device 40 via the circulation path 41, and after solid impurities, water-soluble impurities, etc. are removed by the removal device 40, the water WT is returned to the storage unit 34 via the circulation path 41. With this configuration, it is possible to prevent impurities from accumulating in the storage unit 34 and increasing the amount of impurities in the cleaning liquid. The configuration for removing impurities by the removal device 40 is as described in the first embodiment above.

In this embodiment, the outlet 41A of the circulation path 41 for sending the water WT to the removal device 40 may be disposed on the bottom surface of the storage section 34 or near the bottom surface as shown in FIG. 3. In the storage section 34, solid impurities IP tend to accumulate on the bottom surface of the storage section 34. Therefore, by disposing the outlet 41A on the bottom surface or near the bottom surface, the solid impurities IP are efficiently removed via the outlet 41A.

In the above explanation, the water WT is returned to the storage section 34 via the circulation path 41 after impurities are removed in the removal device 40, but the water WT may be removed as is without being returned to the storage section 34. For example, if the outlet 41A is provided on the bottom surface or near the bottom surface, water with a relatively high proportion of solid impurities IP will be discharged from the outlet 41A, so that even if the water is removed as is, the amount of water in the storage section 34 can be prevented from decreasing significantly. Even if the amount of water decreases, it is advisable to add water to the storage section 34 as appropriate.

Furthermore, in the above description, the configuration in which the water WT is sent from the outlet 41A to the removal device 40 has been shown, but it is not limited to water WT, and the oily substance OL may be sent from the outlet 41A, or a mixture of the oily substance OL and water WT may be sent. In this case, the position of the outlet 41A of the circulation path 41 may be changed as appropriate. In addition, the oily substance OL or the mixture of the oily substance OL and water WT discharged from the outlet 41A may have impurities appropriately removed by the removal device 40 and be returned to the storage section 34, or may be removed without being returned to the storage section 34 in order to prevent the amount of the oily substance OL from becoming too large in the storage section 34.
In addition, two or more outlets 41A may be provided, and the water WT and the oily substance OL may be separately discharged from the storage section 34. In this case, too, the discharged water WT or oily substance OL may be returned to the storage section 34 after impurities are removed by the removal device 40 as described above, or may be discharged as it is.

In this embodiment, as in the first embodiment, the removal device 40 removes a portion of the water WT or oily substance OL from the cleaning liquid stored in the storage section 34, and the ratio of the oily substance OL to the cleaning liquid stored in the storage section 34, and further the ratio of the water WT, may be appropriately adjusted.

In addition, in this embodiment, water and oily substances are selectively recovered using phase separation, but water and oily substances do not have to be recovered using phase separation. For example, an oil-water separation device may be provided, and water and oily substances may be separated in the oil-water separation device, and each of them may be recovered in the first and second recovery paths, and then mixed and contacted with the raw gas as a cleaning liquid. This allows water and oily substances to be selectively recovered even if the water and oily substances do not undergo phase separation in the storage section.
Furthermore, there is no need to provide two supply paths (first and second recovery paths). For example, the amount of water and oily substances can be adjusted by appropriately combining oil-water separation devices, and the ratio of oily substances in the cleaning liquid, or the ratio of oily substances and water in the cleaning liquid, can be set within a predetermined range, and the cleaning liquid can be supplied through a single supply path as in the first embodiment.

[Third embodiment]
Next, a third embodiment of the present invention will be described. The following describes the differences between the first embodiment and the third embodiment. In the scrubber 12 of the first embodiment described above, the cleaning liquid stored in the storage section 12 is circulated and sprayed from the nozzle 15 at the top of the scrubber 12. However, in the scrubber 52 of this embodiment, the nozzle is omitted, and the cleaning liquid WS containing the water WT and the oily substance OL stored in the storage section 54 remains stored in the storage section 54 without being circulated. The inlet 53A of the introduction path 53 is disposed below the liquid level of the cleaning liquid WS stored in the storage section 54.

Therefore, the crude gas G1 introduced from the introduction path 53 is introduced into the cleaning liquid WS stored in the storage section 54. As a result, the crude gas G1 passes through the cleaning liquid WS stored in the storage section 54, and the crude gas G1 comes into contact with the cleaning liquid WS. The crude gas G1 comes into contact with the cleaning liquid WS in the storage section 54, and at least a portion of the water-soluble impurities and oil-soluble impurities contained in the crude gas G1 are removed. The gas from which the water-soluble impurities and oil-soluble impurities have been removed is discharged as purified gas G2 from an exhaust port 59 provided at the top of the scrubber 12.
Furthermore, in this embodiment, as in the first embodiment, the ratio of the oily substance OL in the cleaning solution WS, and further the ratio of the water WT and the oily substance OL are set within the ranges described above, so that the water-soluble impurities and the oil-soluble impurities are efficiently removed from the exhaust gas G1.

In this embodiment, as in the first embodiment, the cleaning liquid WS stored in the storage section 54 is mixed by a stirring means such as a stirring blade. Also in this embodiment, a removal device 60 is provided as an adjustment mechanism. The removal device 60 is connected to the scrubber 52 via a circulation path 61. The configurations of the removal device 60 and the circulation path 61 are similar to those of the removal device 20 and the circulation path 21 in the first embodiment, and therefore a description thereof will be omitted.

However, the cleaning solution WS stored in the storage section 54 does not necessarily need to be mixed by an agitator or the like, and the water WT and the oily substance OL may be phase-separated by being left to stand or the like. In the case of phase separation, as shown in the second embodiment (see FIG. 3), a water layer and an oily substance layer are generally formed in the storage section 54 in this order from the bottom. Therefore, the raw gas G1 is contacted with the water and the oily substance in turn, so that the water-soluble impurities and the oil-soluble impurities are removed. In addition, by making the ratio of the oily substance and further the ratio of the water in the cleaning solution stored in the storage section 54 within the above-mentioned predetermined range, the water-soluble impurities and the oil-soluble impurities are efficiently removed from the exhaust gas G1.
In the third embodiment, as in the first embodiment, a detection device and a control unit are provided, and the removal device 60 (adjustment mechanism) is controlled by the control unit based on the detection results detected by the detection device, so that the proportion of oily substances or the proportion of oily substances and water in the cleaning liquid may be adjusted.

The present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[Test 1]
(blank)
A bottomed cylindrical container (vial) with a capacity of 15 ml and no content was sealed with a rubber stopper. Hydrogen sulfide (H ₂ S) gas was then injected into the sealed container with a syringe in the injection amount shown in Table 1. As the hydrogen sulfide (H ₂ S) gas, a dilution gas containing 1 volume % hydrogen sulfide gas and the remainder (99 volume %) being nitrogen (N ₂ ) was used. The container was then shaken 100 times. Next, 0.1 ml of the gas phase was introduced into a GC/MS to determine the area of the peak derived from hydrogen sulfide, and the hydrogen sulfide concentration in the gas phase was determined based on the peak area in Examples 1 to 5 and Comparative Examples 1 and 2 described later.

In Examples 1 to 5, water and indene were added in the amounts shown in Table 1 to the same container as used in the blank, and the container was sealed with a rubber stopper. In Comparative Examples 1 and 2, water or indene was added in the amounts shown in Table 1 to the same container as used in the blank, and the container was sealed with a rubber stopper. Then, in each Example and Comparative Example, hydrogen sulfide-containing gas was injected into the sealed container in the amount shown in Table 1 using a syringe. The same hydrogen sulfide-containing gas was used as in the blank. Next, the container was shaken 100 times so that the water and indene were mixed with the gas. Then, 0.1 ml of the gas phase was introduced into the GC/MS, and the peak area was determined to determine the hydrogen sulfide concentration in the gas phase. The results are shown in Table 1. The tests were conducted in a room temperature (25°C) environment.

[Test 2]
The gas injected into the sealed container was changed from hydrogen sulfide-containing gas alone to hydrogen sulfide-containing gas and benzene-containing gas, and the injection amounts of these were set as shown in Table 2. With GC/MS, the areas of the peaks derived from hydrogen sulfide and benzene were determined, while the other conditions were the same as in Test 1, and the hydrogen sulfide concentrations and benzene concentrations in the gas phase were determined in Examples 1 to 5 and Comparative Examples 1 and 2. The results of Test 2 are shown in Table 2.
The hydrogen sulfide-containing gas used was the same as in Test 1, and the benzene-containing gas was a dilution gas containing 5% by volume of benzene gas and the remainder (95% by volume) being nitrogen (N ₂ ).

(GC/MS measurement conditions)
The GC/MS measurement conditions in Tests 1 and 2 were as follows.
Measurement equipment: Shimadzu Corporation, GC/MS-QP2020
Column: DB-5MS (Agilent J&W)
Column temperature: 40°C → 280°C
Ionization method: EI
TIC mass range: m/z 29-600

As is clear from the results in Table 1, in Test 1 in which the injected gas was only hydrogen sulfide gas (a water-soluble impurity), the hydrogen sulfide concentration in the gas phase decreased as the volume ratio of indene in the cleaning liquid (liquid phase) increased. This result is believed to be due to the fact that hydrogen sulfide has a higher solubility in indene than in water.
Furthermore, in the case where the injected gas contained both hydrogen sulfide gas (a water-soluble impurity) and benzene gas (an oil-soluble impurity) as in Test 2, the hydrogen sulfide gas in the gas phase decreased as the volume fraction of indene increased, as in Test 1. On the other hand, the benzene gas in the gas phase was sufficiently removed and the concentration decreased even when the volume fraction of indene was 5 volume %, and the concentration decreased even further when the volume fraction was 30 volume % or more. From this, it can be understood that it is effective to include 5 volume % or more of an oily substance in the cleaning solution for removing oil-soluble impurities, and that it is even more effective to increase the proportion of the oily substance.

REFERENCE SIGNS LIST 10 Refined gas production device 11 Raw gas production equipment 12, 32, 52 Scrubber 13 Inlet 13A Inlet 14, 34, 54 Storage section 15, 35 Nozzle 16 Supply path 19, 39, 59 Discharge path 20, 40, 60 Removal device (adjustment mechanism)
21, 41, 61 Circulation path 36A, 36B First and second recovery paths (adjustment mechanism)
A Contact area G1 Raw gas G2 Refined gas IP Solid impurities OL Oily substances WT Water

Claims (16)

A method for producing a purified gas, comprising the steps of: removing at least a portion of water-soluble impurities and oil-soluble impurities from a raw gas derived from waste, the water-soluble impurities and oil-soluble impurities being contained therein, using a scrubber to produce a purified gas, the method comprising the steps of:
a cleaning solution containing water and oily substances is brought into contact with the crude gas in the scrubber to remove at least a portion of the water-soluble impurities and oil-soluble impurities from the crude gas, a portion of the cleaning solution is sent from the scrubber to an adjustment mechanism, the cleaning solution is separated into water and oily substances in the adjustment mechanism, and at least one of the separated water and oily substances is returned to the scrubber; and a proportion of the oily substances in the cleaning solution in the scrubber is 5 volume % or more and 95 volume % or less. The method for producing a refined gas according to claim 1, further comprising adjusting the ratio of the oily substance in the cleaning solution. The method for producing refined gas according to claim 1 or 2, wherein the oily substance includes oil-soluble impurities that have been removed from the crude gas and mixed into the cleaning liquid. The method for producing a refined gas according to any one of claims 1 to 3, wherein the crude gas is a synthetic gas containing the water-soluble impurities and the oil-soluble impurities. The scrubber includes a storage section for storing the water and the oily substance,
5. The method for producing a refined gas according to claim 1, wherein the water and the oily substance are supplied from the reservoir as a washing liquid so as to be brought into contact with the crude gas. The scrubber includes a storage section for storing the water and the oily substance,
6. The method for producing a refined gas according to claim 1, wherein the water and the oily substances are each independently recovered from the reservoir, and the recovered water and the oily substances are mixed together and contacted with the crude gas as the cleaning liquid. The scrubber includes a storage section for storing a cleaning liquid containing the water and the oily substance,
5. The method for producing a purified gas according to claim 1, wherein the crude gas is brought into contact with the cleaning liquid by passing the crude gas through the cleaning liquid stored in the storage section. The method for producing a refined gas according to any one of claims 5 to 7, further comprising removing a portion of the water or oily substance stored in the storage section to adjust the ratio of the oily substance in the cleaning liquid. A method for producing a purified gas, comprising the steps of: removing at least a portion of water-soluble impurities and oil-soluble impurities from a raw gas containing water-soluble impurities and oil-soluble impurities using a scrubber to produce a purified gas,
a cleaning solution containing water and oily substances is brought into contact with the crude gas in the scrubber to remove at least a portion of the water-soluble impurities and oil-soluble impurities from the crude gas; and a portion of the cleaning solution is sent from the scrubber to an adjustment mechanism, where it is separated into water and oily substances, and at least one of the separated water and oily substances is returned to the scrubber, thereby adjusting the ratio of the oily substances in the cleaning solution. A refined gas production apparatus for producing a refined gas by removing at least a portion of water-soluble impurities and oil-soluble impurities from a raw gas containing the water-soluble impurities and oil-soluble impurities,
a scrubber that contacts the crude gas with a wash liquid containing water and oily substances to remove at least a portion of the water-soluble impurities and oil-soluble impurities from the crude gas;
an adjusting mechanism capable of adjusting the ratio of the oily substance in the cleaning liquid;
Equipped with
A refined gas production apparatus in which a portion of the cleaning liquid is sent from the scrubber to the adjustment mechanism, where it is separated into water and oily substances, and at least one of the separated water and oily substances is returned to the scrubber, thereby adjusting the proportion of the oily substances in the cleaning liquid. The refined gas production apparatus according to claim 10, wherein the proportion of the oily substance in the cleaning liquid is 5% by volume or more and 95% by volume or less. The refined gas production apparatus according to claim 10 or 11, wherein the scrubber has a storage section for storing the water and the oily substances, and is provided with a supply passage for supplying the water and the oily substances from the storage section so as to contact the crude gas as the cleaning liquid. The scrubber has a storage section for storing the water and the oily substance, and the adjustment mechanism includes first and second recovery paths,
12. The refined gas production apparatus according to claim 10 or 11, wherein each of the first and second recovery paths independently recovers the water and oily substances in the storage section, and mixes the recovered water and oily substances to form the cleaning liquid, which is then contacted with the crude gas. The scrubber has a storage section for storing a cleaning liquid containing the water and the oily substance,
The refined gas production apparatus according to claim 10 or 11, further comprising an introduction passage for introducing the crude gas into the cleaning liquid stored in the storage section. The refined gas production apparatus according to any one of claims 12 to 14, wherein the adjustment mechanism is a removal device that removes a portion of the water or oily substance stored in the storage section. A refined gas production apparatus for producing a refined gas by removing at least a portion of water-soluble impurities and oil-soluble impurities from a raw gas containing the water-soluble impurities and oil-soluble impurities,
A scrubber that brings a cleaning liquid containing water and an oily substance into contact with the crude gas to remove at least a portion of the water-soluble impurities and the oil-soluble impurities from the crude gas; and an adjustment mechanism,
A portion of the cleaning liquid is sent from the scrubber to the adjustment mechanism, and separated into water and oily substances in the adjustment mechanism, and at least one of the separated water and oily substances is returned to the scrubber;
A refined gas production apparatus, wherein the proportion of the oily substance in the cleaning liquid in the scrubber is 5 volume % or more and 95 volume % or less.

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