JP2018002949A - Recovery apparatus of crude gas oil component in gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for efficiently recovering a crude gas oil component contained in a coke oven gas or a pyrolysis furnace gas.SOLUTION: The recovery apparatus of a crude gas oil component in a gas comprises an absorption column for absorbing a crude gas oil component contained in a raw material gas from the raw material gas containing at least either of a coke oven gas and a pyrolysis furnace gas into an absorption oil, a distillation column for recovering the crude gas oil component from the absorption oil in which the crude gas oil component has been absorbed in the absorption column, a line (1) for mixing the absorption oil after recovering the crude gas oil component in the distillation column with a component derived from a coke gas, which is different from the absorption oil, to form a mixed oil, a separation unit for separating a pitch component from the mixed oil and a line (2) for circulating a recovery oil after separating the pitch component from the mixed oil in the separation unit into the absorption column.SELECTED DRAWING: Figure 3

Description

The present invention relates to an apparatus for recovering crude light oil components contained in coke oven gas or pyrolysis oven gas.
More specifically, the present invention relates to a coke oven gas produced as a by-product when coke is produced by carbonizing in a coke oven or a pyrolysis oven gas generated when coal is pyrolyzed in a pyrolysis oven. The present invention relates to an apparatus for recovering the contained crude light oil component.

  Coke oven gas generated when coke is produced by carbonization in a coke oven, and pyrolysis oven gas generated when coal is pyrolyzed in a pyrolysis oven (hereinafter collectively referred to as “coke oven gas”) Etc.))) are the main components of hydrogen, methane, carbon monoxide, carbon dioxide, etc. In addition to these main components, tar content, ammonia, hydrogen sulfide, hydrocarbon gases other than methane, It contains crude light oil components, hydrogen cyanide and many other components. Since coke oven gas and the like are generated in a high temperature state from a coke oven and a coal pyrolysis furnace, the coke oven gas is first cooled, and then the above components are separated and recovered. Each component recovered from coke oven gas or the like is utilized as fuel or various raw materials. Above all, crude light oil components recovered from coke oven gas contain a large amount of aromatic hydrocarbon compounds (aromatic compound components) such as benzene, toluene, xylene, etc., compared to petroleum-derived light oil components. Therefore, it is highly useful as various raw materials.

  Various methods are used to recover crude light oil components from coke oven gas etc., but as a typical method, coke oven gas etc. are brought into contact with absorbing oil in an absorption tower and included in coke oven gas etc. The crude light oil component to be absorbed is absorbed into the absorption oil, and the crude oil component is separated and recovered from the absorption oil by distilling the absorption oil in the distillation tower, and the absorption oil after separation and recovery is circulated to the absorption tower. (See FIG. 1).

In the above method, in order to efficiently recover crude light oil components such as benzene, toluene, xylene from coke oven gas, etc., the absorption light tower absorbs a large amount of crude light oil components in the absorption oil, and efficiency in the distillation tower. It is preferable to separate well. For that purpose, it is necessary to lower the temperature of the absorption oil led to the absorption tower and increase the amount of the crude light oil component absorbed in the unit absorption oil amount.
On the other hand, as described above, since the absorption oil is circulated and used, the absorption oil discharged in a high temperature state in the distillation tower needs to be cooled using a cooler. Therefore, in order to efficiently recover the crude light oil, it is preferable to cool the absorption oil discharged from the distillation tower to a lower temperature and supply it to the absorption tower.

  However, since various components are dissolved in the absorbing oil discharged from the distillation tower, when the temperature of the absorbing oil is lowered too much, these dissolved components are deposited on the inner wall of the cooler and the pipe. Precipitation of dissolved components from the oil absorption on the inner wall of the cooler or piping, etc. will lead to a decrease in cooling capacity and an increase in fluid / gas flow resistance, leading to blockage of the cooler and piping. It was a problem.

  Conventionally, two coolers are arranged in parallel and bypassed, and when one of the coolers is blocked, it is necessary to switch to the other cooler and to clean the blocked cooler openly . However, since it takes a lot of labor to open and clean the cooler, a method for preventing precipitation of dissolved components while cooling the absorbing oil to a lower temperature is desired.

  As a means for preventing the dissolved components in the absorbent oil from precipitating in the cooler or the like, for example, a method is disclosed in which a tar heated to 60 ° C. or more is washed at a predetermined interval in a pipe through which the absorbent oil flows. (See Patent Document 1). Further, as a method for efficiently recovering crude light oil from the absorbent oil, the composition of the absorbent oil in each part where the absorbent oil circulates is obtained, and after calculating the precipitation start temperature of the absorbent oil from the composition, the operation of each part is performed. A method is disclosed in which the composition of the absorbent oil is changed so that the conditions are equal to or higher than the precipitation start temperature or the precipitation start temperature of the absorbent oil is lowered (see Patent Document 2).

JP 2004-138359 A JP 2005-194410 A

  As described above, conventionally, when recovering crude light oil components from coke oven gas or the like, as a means for preventing dissolved components in the absorption oil from precipitating in the cooler or the like, the temperature at which the precipitate is washed away or does not precipitate Only the method of cooling in the range was disclosed. However, in the former method, a long time is required for cleaning, and a sufficient precipitation suppressing effect is not observed. Further, the latter method is complicated because the composition of the absorbed oil must be analyzed at various places in the facility, and the original purpose of efficiently recovering crude light oil components cannot be achieved in the first place.

  In addition, as described above, although a method of changing the composition of the absorbing oil so as to lower the precipitation start temperature of the absorbing oil has been disclosed, an examination focusing on dissolved substances from the viewpoint of what component precipitation should be suppressed The current situation is that no sufficient effect has been obtained yet.

  On the other hand, the present inventors examined a device for recovering crude light oil components in the gas shown in FIG. In this recovery device, a crude gas oil component is obtained from a raw gas such as a coke oven gas, an absorption tower that absorbs the crude light oil component contained in the raw material gas into the absorption oil, and an absorption oil that has absorbed the crude light oil component in the absorption tower. Distillation tower to be recovered, depitch tower for removing dibenzofuran and / or fluorene by steam distillation from the absorption oil after the crude light oil component is recovered in the distillation tower, recovered oil after removal of the pitch component from the mixed oil to the absorption tower It is equipped with a circulating line. This recovery device is excellent in that it can lower the temperature of the absorption oil, but there is room for study to improve the recovery rate of crude light oil components represented by BTX (benzene, toluene, xylene) and the like. .

  An object of this invention is to provide the apparatus which can collect | recover efficiently the crude light oil components contained in coke oven gas or pyrolysis furnace gas. In addition, when recovering the crude light oil component contained in the gas using the absorbent oil, the present invention may cause precipitation or the like in the heat exchanger or piping even if the temperature of the absorbent oil is lowered to increase the absorption efficiency. An object of the present invention is to provide an apparatus for recovering crude light oil components that are not present. Furthermore, the present invention can efficiently absorb the crude light oil component contained in the coke oven gas or pyrolysis furnace gas into the absorption oil, and reduce the content ratio of the crude light oil component remaining in the gas after absorption. An object of the present invention is to provide a simple crude light oil component recovery device.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors do not adopt an apparatus configuration in which the absorption oil after the crude light oil component is recovered in the distillation tower is recycled to the absorption tower as it is, but a separation apparatus is used. The present invention has been completed by finding that the above-described problems can be solved by adopting an apparatus configuration for recycling to an absorption tower after a lapse of time.

That is, the gist of the present invention is the following [1] to [4].
[1] An absorption tower that absorbs a crude light oil component contained in the raw material gas from the raw material gas containing at least one of the coke oven gas and the pyrolysis furnace gas into the absorbing oil,
A distillation column for recovering crude gas oil components from the oil absorbed by the absorption tower.
A line (1) for mixing a mixed oil by mixing an absorption oil after recovering a crude light oil component in a distillation tower and an oil containing an aromatic compound component different from the absorption oil;
A separation device for separating pitch components from the mixed oil;
The recovery apparatus of the crude light oil component in gas which has the line (2) which circulates the recovered oil after isolate | separating a pitch component from mixed oil with a separator to an absorption tower.

[2] The apparatus for recovering crude light oil components in gas according to [1], wherein the separation device for separating the pitch components from the mixed oil is a distillation column.
[3] The apparatus for recovering a crude light oil component in gas according to [2], wherein the distillation column for separating the pitch component from the mixed oil is a plate column or a packed column.
[4] The apparatus for recovering crude light oil components in gas according to any one of [1] to [3], wherein the line (2) includes a heat exchanger for cooling the recovered oil.

  ADVANTAGE OF THE INVENTION According to this invention, the apparatus which can collect | recover efficiently the crude light oil component contained in coke oven gas or pyrolysis furnace gas can be provided. In addition, according to the present invention, when the crude light oil component contained in the gas is recovered using the absorption oil, even if the temperature of the absorption oil is lowered in order to increase the absorption efficiency, it is deposited on the heat exchanger, piping, etc. It is possible to provide a crude light oil component recovery device that does not cause the problem. Furthermore, according to the apparatus of the present invention, since the crude light oil component contained in the coke oven gas or the pyrolysis furnace gas can be efficiently absorbed into the absorption oil, the crude light oil component remaining in the gas after absorption is reduced. The content ratio can be lowered, and the purification load can be reduced.

It is a schematic diagram which shows an example of the general method which collect | recovers crude light oil components from coke oven gas. It is a schematic diagram which shows an example of the collection | recovery apparatus shown in order to contrast with the collection | recovery apparatus of the crude light oil component of this invention. It is a schematic diagram which shows an example of the collection | recovery apparatus of the crude light oil component of this invention.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In the following, “mass%” and “wt%” and “part by mass” and “part by weight” have the same meaning.

The apparatus for recovering crude light oil components in the gas according to the present invention absorbs the crude light oil components contained in the raw gas from the raw gas containing at least one of the coke oven gas and the pyrolysis furnace gas. Absorption tower, distillation tower that collects crude gas oil component from absorption oil that has absorbed crude gas oil component in absorption tower, absorption oil after crude gas oil component is collected in distillation tower, and aromatic compound component that is different from the absorption oil (1) which mixes the oil component containing oil into a mixed oil, a separation device for separating the pitch component from the mixed oil, and the recovered oil after separating the pitch component from the mixed oil by the separation device is circulated to the absorption tower It has a line (2).
In the present invention, the coke oven gas and the pyrolysis oven gas may be collectively referred to as “coke oven gas”.
The present invention is described in detail below.

[1. Raw material gas]
<Coke oven gas>
The coke oven gas means a gas generated from the coke oven when coke is produced from coal. Specifically, coke oven gas is a gas that is generated when coal is heated and distilled at a temperature of 600 ° C. or higher to produce coke. As a general composition, hydrogen is 10 to 70% by volume, methane 20 to 70. Volume%, hydrocarbons other than methane (olefins such as ethylene) 1 to 15 volume%, carbon monoxide 4 to 9 volume%, carbon dioxide 1 to 6 volume%, nitrogen 1 to 13 volume%, oxygen 0 to 0 0.5% by volume, sulfur compounds such as hydrogen sulfide 0.3 to 1.5%, nitrogen compounds such as ammonia 0.3 to 1.8%, benzoles 0.1 to 1.8% by volume, and other coals Contains trace components of origin.

  As the coke oven gas used in the apparatus of the present invention, the gas having the above composition discharged from the coke oven can be used as it is, but it is preferable to use a pretreated coke oven gas. Specifically, it is preferable to use a coke oven gas that has been subjected to a purification treatment for reducing sulfur compounds such as hydrogen sulfide, nitrogen compounds such as ammonia, and benzols among the above components.

The pretreatment can be performed using, for example, a catalyst for deoxygenation reaction having a function as a desulfurization catalyst, such as a Ni—Mo-based catalyst or a Co—Mo-based catalyst. When these catalysts are used, deoxygenation and desulfurization are performed by hydrogenation with hydrogen in coke oven gas. The pretreatment may be performed according to a conventional method. For example, the treatment may be performed under conditions of a reactor inlet temperature of about 200 to 350 ° C., a reactor internal pressure of about 0.5 to 5.0 MPaG, and a reactor outlet temperature of about 100 to 450 ° C. That's fine. Further, for example, coke oven gas may be sent to an adsorption desulfurizer to perform adsorption desulfurization with ZnO.
The concentration of each component of the pretreated coke oven gas is generally 0.001 to 0.2% of a sulfur compound such as hydrogen sulfide, 0.01 to 0.2% of a nitrogen compound such as ammonia, and benzols 0 0.02 to 0.3%, and the concentration of components other than these is substantially unchanged before and after the purification treatment.

  The composition of the coke oven gas used in the apparatus of the present invention is not limited, but usually contains hydrogen, carbon dioxide, carbon monoxide, methane, nitrogen and the like as main components and a crude light oil component.

  Although the content rate of the crude light oil component in the coke oven gas used for the apparatus of this invention is not limited, Usually, it is 1-5000 volume ppm. When the content ratio of the crude light oil component in the coke oven gas is within the above range, it is preferable because the crude light oil component tends to be efficiently absorbed by the absorbent oil in the absorption step. For the same reason as described above, the lower limit of the content ratio of the crude light oil component in the coke oven gas is preferably 10 ppm by volume or more, more preferably 100 ppm by volume or more, still more preferably 500 ppm by volume or more, particularly preferably 1000 volumes. ppm or more. Moreover, the upper limit of the content ratio of the crude light oil component in the coke oven gas is preferably 4000 ppm by volume or less, more preferably 3000 ppm by volume or less, for the same reason as described above.

  In particular, the total content of benzene, toluene and xylene contained in the coke oven gas is preferably 1 to 4000 ppm by volume from the viewpoint of the feature of the present invention in which useful components are recovered more efficiently. Further, the lower limit of the total content is preferably 10 volume ppm or more, more preferably 100 volume ppm or more, still more preferably 500 volume ppm or more, particularly preferably 1000 volume ppm or more, and the upper limit is preferably 3000. Volume ppm or less.

The raw material gas used in the apparatus of the present invention may be any one of coke oven gas and pyrolysis furnace gas, but preferably contains at least coke oven gas. The content ratio of the coke oven gas in the raw material gas is not limited, but is usually 1% by volume or more, preferably 10% by volume or more, more preferably 50% by volume or more, still more preferably 70% by volume or more, and particularly preferably 85% by volume. That's it. The upper limit of the content ratio of the coke oven gas is not limited, and may be 100% by volume.

<Pyrolysis furnace gas>
The pyrolysis furnace gas means a gas generated when coal is pyrolyzed in the pyrolysis furnace. The composition of the pyrolysis furnace gas used in the present invention is not limited, but usually contains hydrogen, carbon dioxide, carbon monoxide, methane, nitrogen and the like.

Although the content rate of the crude light oil component in the pyrolysis furnace gas used for the apparatus of this invention is not limited, Usually, it is 1-5000 volume ppm. When the content ratio of the crude light oil component in the pyrolysis furnace gas is within the above range, it is preferable because the crude light oil component tends to be efficiently absorbed by the absorption oil in the absorption tower. Moreover, the minimum and upper limit of a preferable content rate are the same as that of coke oven gas mentioned above.
In particular, the total content of benzene, toluene, and xylene contained in the pyrolysis furnace gas is preferably 1 to 4000 ppm by volume from the viewpoint of the feature of the present invention that recovers useful components more efficiently. Moreover, the minimum and upper limit of a preferable total content rate are the same as that of coke oven gas mentioned above.

  In the apparatus of the present invention, coke oven gas and pyrolysis oven gas may be used in combination as raw material gas. Even when the coke oven gas and the pyrolysis oven gas are used in combination, the content ratio of the crude light oil component in the raw material gas obtained by mixing both is preferably 1 to 5000 ppm by volume.

  The coke oven gas and pyrolysis oven gas in the present invention are not necessarily formed in a complete gas state, and may be aerosols such as dust, fume, smoke, mist, etc. The thing of a state may be contained. Furthermore, a liquid or solid form formed by agglomeration or solidification of a gas is also included.

  Both the gas composition in the coke oven gas and the pyrolysis oven gas and the content ratio of the crude light oil component can be measured by a gas chromatography apparatus.

<Other raw materials>
In the crude light oil component recovery apparatus of the present invention, any raw material can be used in combination with the coke oven gas and / or the pyrolysis furnace gas (hereinafter referred to as “other raw materials other than the coke oven gas and pyrolysis furnace gas”. ”). The other raw material may be a gas, a solid or a liquid, but is preferably a gas in a state mixed with a coke oven gas and / or a pyrolysis oven gas (including the state described above). .

<Coarse light oil component>
In the present invention, the crude light oil component broadly includes what is generally called light oil (light oil). Specifically, it means a component that can be absorbed from the raw material gas into the absorption oil, and includes at least benzene, It preferably contains any component selected from toluene and xylene. Usually, the crude light oil component further contains styrene, benzofuran, indene, naphthalene, methylnaphthalene, biphenylene, acenaphthene, biphenyl, ethylnaphthalene, dimethylnaphthalene, fluorene, dibenzofuran, phenanthrene, anthracene, fluoranthene, pyrene and the like. The crude light oil component may be a single compound, but is usually a mixture of a plurality of compounds.

As a raw material gas to be introduced into an absorption tower described later, the total content of benzene, toluene and xylene in the total crude light oil component contained in the raw material gas is preferably 10% by volume or more, and 30% by volume or more. More preferably, it is more preferably 50% by volume or more. The upper limit of the total content of benzene, toluene and xylene in the total crude light oil component is not limited, and may be 100% by volume, but is usually 90% by volume or less.

[2. Absorption tower]
In the present invention, the crude light oil component contained in the gas is absorbed into the absorption oil by the absorption tower from the raw material gas containing at least one of the coke oven gas and the pyrolysis oven gas. More specifically, the raw material gas is supplied to the absorption tower, the raw material gas and the absorbing oil are brought into contact with each other, and the crude light oil component in the raw material gas is absorbed by the absorbing oil.

  In the present invention, the absorption tower is charged with absorbing oil from the upper part to the lower part of the tower, and with the raw material gas charged from the lower part to the upper part, and the absorbing oil and the raw material gas are contacted in the tower. Thus, the crude light oil component contained in the raw material gas is a device in which the phase is shifted into the absorption oil. The method for charging the absorbing oil in the absorption tower is not limited, but a packed tower or a spraying system is preferred.

<Absorbing oil>
Although the absorption oil used for the apparatus of this invention is not limited, Specifically, coal tar distillation fractionation oil, diesel oil, B heavy oil etc. are mentioned. Among these, coal tar distillate fraction is preferable because of its simplicity available from a coke plant. The coal tar distillation fraction oil is an oil obtained by distilling coal tar and obtained from other than the bottom of the distillation column. Specific examples include carbol oil, naphthalene oil, anthracene oil, creosote oil, and the like.

  In the apparatus of the present invention, since the absorbing oil is used in a circulating manner, the absorbing oil in the system exists in a state where the substance derived from the crude light oil component is dissolved in the absorbing oil. In other words, even if the absorbing oil is derived from the oil exemplified above, it is substantially constituted as a mixture of the compounds mentioned as the crude light oil component. That is, as each process of the absorption process, the recovery process, and the like is circulated as in the present invention, the crude light oil component itself becomes the absorption oil, and circulates with its composition ratio varied.

<Absorption method>
The temperature of the raw material gas charged into the absorption tower is not limited, but is usually 10 to 50 ° C. Moreover, although the temperature of the absorption oil with which an absorption tower is charged is not limited, since it is necessary to control to the temperature which does not produce blockage in the line (2) mentioned later, it is about 30-50 degreeC normally. The lower the temperature, the higher the absorption efficiency of the crude light oil component in the raw material gas. In the present invention, by controlling the ratio of the components dissolved in the absorption oil, the temperature of the absorption oil charged into the absorption tower is set to 30 ° C. or lower, further 25 ° C. or lower, particularly 20 ° C. or lower. be able to.

  The total content of benzene, toluene and xylene contained in the absorption oil that absorbs the crude light oil component and is discharged from the absorption tower is usually about 1% by weight, but in the present invention, the crude light oil component is used as described above. Since it can collect | recover efficiently, it can be 1.1 weight% or more, Furthermore, it can be 1.2 weight% or more.

[3. Distillation tower]
In this invention, the said crude light oil component is collect | recovered by distilling the absorption oil which absorbed the crude light oil component in the distillation tower.

Although the distillation method of the distillation tower is not limited, the steam distillation method is preferred from the viewpoint of removing inorganic salts. That is, the absorption oil having absorbed the crude light oil component is supplied to the steam distillation tower and subjected to steam distillation, the crude light oil component and water are distilled from the top of the tower, and the absorption oil is recovered from the bottom of the tower.
Hereinafter, the case of steam distillation will be described as an example in detail. However, when a distillation method other than steam distillation is adopted, it can be implemented with appropriate modifications.

  Although the temperature of the absorption oil which absorbed the crude light oil component charged into a steam distillation tower is not limited, it is usually 100 to 200 ° C. In addition, although the temperature of the absorption oil which absorbed the crude light oil component and was discharged | emitted from the absorption tower is 15-50 degreeC normally, when this is directly charged into a steam distillation tower, the thermal energy required for distillation will become large, It is preferable that the temperature is raised to the above-mentioned temperature in advance and charged into the steam distillation column. Moreover, the top temperature of the steam distillation column is not limited and is set depending on the composition of the crude light oil component to be recovered, but is usually 90 to 110 ° C.

  Since steam containing a crude light oil component and water usually flows out from the top of the steam distillation column, after condensing the steam, the crude light oil component and water are separated by a difference in specific gravity to recover the crude light oil.

  Since the steam distillation tower consumes a large amount of water vapor, the energy consumption is large. For this reason, it is preferable to make the equipment as compact as possible. In order to reduce the energy consumed in steam distillation at a constant feed gas throughput or a constant crude light oil component recovery amount, the content ratio (concentration) of the crude light oil component absorbed in the absorption oil in the absorption process is set. Need to be high. In this invention, since it can be set as the absorption oil which contains the crude light oil component in higher concentration, the quantity of the absorption oil which circulates in the system can be reduced. For this reason, since it becomes possible to reduce the usage-amount of the water vapor | steam in a steam distillation tower, it also becomes possible to make an installation compact.

Crude light oil components discharged together with water vapor from the top of the steam distillation tower and separated from water are mainly composed of benzene, toluene and xylene, but the total content of benzene, toluene and xylene in the crude light oil components The proportion is usually 70 to 100% by weight.
After recovering the crude light oil component, the total content of benzene, toluene and xylene contained in the absorption oil discharged from the steam distillation tower is usually 1 to 5000 ppm by weight.

[4. Line (1)]
In the apparatus of the present invention, the line (1) in which the absorption oil after the crude light oil component is recovered in the distillation tower and the oil component containing an aromatic compound component different from the absorption oil are mixed to form a mixed oil is provided. Have.

  Here, the “oil containing an aromatic compound component” includes a heavy component in coke oven gas such as coal tar produced by dry distillation of coal. More specifically, there is a drain generated when the coke oven gas discharged from the furnace is cooled.

  The line (1) is not particularly limited as long as it mixes the absorption oil and the mixed oil, and may be a normal line. Usually, the said absorption oil and the said absorption oil can be mixed by making the oil component containing a different aromatic compound component merge.

<Mixed oil>
The mixed oil in line (1) is a mixture of the absorbent oil and an aromatic compound component different from the absorbent oil. The mixing ratio is not particularly limited, but usually [weight of absorbing oil]: [weight of aromatic compound component different from absorbing oil] is 1: 1 to 1: 1000, preferably 1: 1 to 1. 1: 200.

[5. Separation device]
The separation device in the recovery device of the present invention is a device for separating a pitch component from the mixed oil. Although the kind of this separation apparatus is not limited, Specifically, a distillation column can be mentioned.
Examples of the distillation column include a plate column or a packed column (see FIG. 3). Absorbed oil discharged from the distillation tower contains heavy components such as dibenzofuran, fluorene, acenaphthene, and phenanthrene while the content ratio of benzene, toluene, and xylene is reduced. In the separation device, these heavy components can be separated and removed from the mixed oil.

  As described above, in the separation device, mixed oil obtained by mixing the oil containing the crude light oil component in the absorption tower and the oil component containing the aromatic compound component such as coal tar is introduced into the separation device (see FIG. 3). . Further, part of the absorption oil discharged from the separation device can be made into products such as pitch coke and creosote oil, and the remainder can be recycled to the absorption tower.

  The temperature of the mixed oil obtained by mixing coal tar and absorbing oil discharged from the distillation tower and charged into the separator is not limited, but is usually 200 to 400 ° C. The tower top temperature of the separation apparatus is not limited and is appropriately set depending on the composition of the pitch component to be removed and the like, but is usually 90 to 150 ° C. Moreover, the content rate of the crude light oil component in the absorption oil which removed the pitch component and is discharged | emitted from a separator is 37 to 32 weight% normally.

Absorbed oil separated into the absorption tower and recycled to the absorption tower can be cooled with a heat exchanger.
The pitch component discharged from the separator usually contains dibenzofuran and fluorene, but the total content of dibenzofuran and fluorene in the total pitch component is usually 30 to 70% by weight, and is 50% by weight or more. It is preferable.

  The pitch component discharged by the separation device can be used as a fuel, but can be used as various raw materials. Specifically, it can be used as pitch coke, creosote oil or the like.

[6. Line (2)]
In this invention, the absorption oil after isolate | separating a pitch component from the said mixed oil with a separator is made to circulate to an absorption tower by a line (2). At this time, the recovered oil circulated to the absorption tower is cooled in the line (2).

  In order to efficiently cool the recovered oil, the line (2) preferably has a heat exchanger. Since the line (2) has a heat exchanger, the temperature of the absorbing oil can be cooled to about 15 ° C to 30 ° C.

  In the line (2), a recovered oil tank for storing recovered oil that has been cooled and circulated to the absorption tower may be provided as appropriate.

Claims (4)

An absorption tower for absorbing the crude light oil component contained in the raw material gas from the raw material gas containing at least one of the coke oven gas and the pyrolysis furnace gas,
A distillation column for recovering crude gas oil components from the oil absorbed by the absorption tower.
A line (1) for mixing a mixed oil by mixing an absorption oil after recovering a crude light oil component in a distillation tower and an oil containing an aromatic compound component different from the absorption oil;
A separation device for separating pitch components from the mixed oil;
The recovery apparatus of the crude light oil component in gas which has the line (2) which circulates the recovered oil after isolate | separating a pitch component from mixed oil with a separator to an absorption tower.   The apparatus for recovering crude light oil components in gas according to claim 1, wherein the separation device for separating the pitch components from the mixed oil is a distillation column.   The apparatus for recovering a crude light oil component in gas according to claim 2, wherein the distillation column for separating the pitch component from the mixed oil is a plate column or a packed column.   The recovery apparatus of the crude light oil component in the gas of any one of Claims 1-3 which has a heat exchanger which cools recovered oil in the said line (2).

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