JP7554036B2 - Method for treating contents of reaction tower, method for extracting contents of reaction tower, and hydrocarbon oil - Google Patents

Description

The present invention relates to a method for treating the contents of a reaction tower, a method for extracting the contents of a reaction tower, and a hydrocarbon oil.

Various catalysts are used in the reactors of oil refineries and chemical plants, and as the activity of the catalyst decreases, it becomes necessary to remove and refill the catalyst to replace it. Catalyst replacement requires workers to enter the reactor and temporarily remove structures inside the reactor, such as the scale basket and distributor tray manway, and, if necessary, to discharge catalyst remaining in the reactor, so ensuring a safe working environment is extremely important.

For example, in a desulfurization reactor in which catalytic reactions using a catalyst are carried out in a desulfurization apparatus for various petroleum fractions, iron sulfide formed due to corrosion of the apparatus and coke-like substances formed due to various petroleum fractions are deposited on the catalyst layer packed in the reactor, and the catalyst, iron sulfide, coke-like substances, etc. are present. In addition, when a sulfide catalyst is used as a catalyst for the desulfurization reaction, if the sulfide catalyst, iron sulfide, coke-like substances, etc. come into contact with air, heat generation and fire are likely to occur even after the apparatus is safely stopped and the temperature inside the reactor is lowered, and furthermore, toxic gases such as sulfur oxides, hydrogen sulfide, and other sulfur-containing gases are likely to be generated, so work inside the reactor with air introduced into it cannot be said to be highly safe work.

Therefore, when replacing the catalyst in the desulfurization reactor in the desulfurization equipment, the method that has been generally adopted is to replace the inside of the reactor with an inert gas such as nitrogen, temporarily remove the structures inside the reactor, and discharge the contents of the reactor, such as the catalyst, iron sulfide, and coke-like substances that are prone to heat generation and ignition, from the reactor, and then introduce air (hereinafter, sometimes simply referred to as the "conventional method"). In the conventional method, the work of removing the structures inside the reactor is performed inside the reactor while wearing an airline mask under a nitrogen atmosphere. However, if the airline mask comes off, it can immediately lead to an oxygen deficiency accident, and air leaking from the airline mask can cause the contents of the reactor to heat up and ignite, so it has been strongly recommended from a safety perspective to avoid work under a nitrogen atmosphere as much as possible.

In order to meet such demands, Patent Document 1 proposes a method of circulating a mixed liquid of condensed ring aromatic hydrocarbons and diesel in a reaction tower, diffusing the mixed liquid on the catalyst surface and in the pores in the reaction tower to form a coating, and extracting the catalyst. Other proposed methods include a catalyst extraction method in which the catalyst is infiltrated by circulating water or mineral oil containing lactones, and a catalyst extraction method in which the catalyst is infiltrated by circulating mineral oil-based hydrocarbons containing specific amines (see, for example, Patent Documents 2 and 3).

Japanese Unexamined Patent Publication No. 15127/1986 Japanese Patent Application Publication No. 55-61970 Japanese Unexamined Patent Publication No. 52-93677

According to the methods described in Patent Documents 1 to 3, the spent catalyst does not generate heat or ignite even when it comes into contact with air, so it is possible to introduce air into the reaction tower, and the removal of the structure inside the reaction tower and the extraction of the catalyst can be safely performed, and there are also advantages in that the spent catalyst can be easily recovered. On the other hand, in these methods, the treatment liquid such as the above-mentioned mixed liquid used in the infiltration treatment and the like must be circulated through multiple devices, so preparation and circulation work for circulating the treatment liquid are required. In addition, for example, in desulfurization equipment for kerosene, naphtha, etc., there is no line for circulating the treatment liquid, and infiltration treatment and the like cannot be performed. In addition, in a desulfurization equipment for naphtha, the desulfurization reaction is performed in the gas phase, so there are cases where the treatment liquid cannot be supplied into the reaction tower, and the methods described in Patent Documents 1 to 3 lack versatility. In other words, the application of the methods disclosed in Patent Documents 1 to 3 is currently limited to desulfurization equipment for petroleum fractions having a boiling point equal to or higher than that of light oil fractions.
Therefore, an object of the present invention is to provide a method for treating the contents of a reactor which is applicable to reactors for a wide range of petroleum fractions, and further for petrochemical fractions derived from plants for producing petrochemical products, such as ethylene production plants, and which easily suppresses the generation of heat, fire, and toxic gases, such as sulfur-containing gases, a safe and efficient method for extracting the contents of a reactor, and a hydrocarbon oil.

As a result of extensive research into solving the above problems, the inventors have discovered that the problems can be solved by the following invention. That is, the present invention provides a method for treating the contents of a reaction tower, a method for extracting the contents of a reaction tower, and a hydrocarbon oil, each having the following configuration.

1. A method for treating the contents of a reaction tower, comprising a wetting step of wetting at least the outermost surface layer of the contents of the reaction tower by spraying a hydrocarbon oil from an upper portion of the reaction tower.
2. A method for extracting the contents of a reaction tower, comprising the steps of: a wetting step in the method for treating the contents of a reaction tower described in 1 above; a step of introducing air into the reaction tower from the top and removing the internal structure of the reaction tower; and a step of extracting the contents of the reaction tower.
3. A hydrocarbon oil having a flash point of 100° C. or higher, a 40° C. kinetic viscosity of 2.0 mm ² /s to 60.0 mm ² /s, a viscosity index of 75 to 120, a sulfur content of 500 mass ppm or lower, and an aromatic content (% C _A ) of 10% or lower, which is used for wetting the contents of a reaction tower.

The present invention can provide a method for treating the contents of a reaction tower that can be applied to a wide range of petroleum fractions and petrochemical fractions, and that easily suppresses heat generation, ignition, and the generation of toxic gases such as sulfur-containing gases, a safe and efficient method for extracting the contents of a reaction tower, and a hydrocarbon oil.

FIG. 2 is a schematic diagram showing a cross section of the inside of a desulfurization reaction tower in a naphtha desulfurization unit and a kerosene desulfurization unit.

[Method of treating the contents of the reaction tower]
The method for treating the contents of a reaction tower according to an embodiment of the present invention (hereinafter, sometimes simply referred to as the present embodiment) includes a wetting step of wetting at least the outermost surface layer of the contents of the reaction tower by spraying a hydrocarbon oil from the upper part of the reaction tower. Hereinafter, the method for treating the contents of a reaction tower according to the present embodiment will be described in detail with reference to the drawings, etc.

In FIG. 1 (1-1), a cross-sectional view of a desulfurization reaction tower in which a desulfurization reaction is performed in a naphtha desulfurization device is shown as an example of the structure of a reaction tower in the reaction tower content treatment method of this embodiment. In the desulfurization reaction tower 10 shown in FIG. 1 (1-1), as the reaction tower internal structure, an inlet distributor 11 is provided at the top to disperse raw oil (mainly gaseous) in the desulfurization reaction tower 10, and a scale basket 12 is provided as necessary to collect powder such as iron sulfide and coke-like substances and to secure a flow path. In the desulfurization reaction tower 10, the reaction tower contents are filled in layers of ceramic balls, descaling catalyst, guard catalyst, and desulfurization catalyst from the top, and the ceramic ball filling layer (upper layer) 16a, descaling catalyst filling layer 17, guard catalyst filling layer 18, desulfurization catalyst filling layer 19, and ceramic ball filling layer (lower layer) 16b are stacked in order. Under the ceramic ball packed bed (lower layer) 16b, an outlet collector using a cylindrical wire mesh, a structure with slits, etc. is provided (not shown) to prevent the reaction tower packing that forms these packed beds from flowing down. In addition, at the top of the desulfurization reaction tower 10, there is a top elbow 13 that supplies raw oil to the reaction tower, at the bottom of the desulfurization reaction tower 10, there is a damping nozzle 14 for extracting the catalyst, etc. by its own weight, and at the bottom, there is an outlet 15 for the desulfurized raw oil.

In FIG. 1 (1-2), a cross-sectional view of a desulfurization reaction tower in a kerosene desulfurization apparatus is shown as an example of the structure of a reaction tower in the method for treating the contents of a reaction tower according to the present embodiment. In the desulfurization reaction tower 20 shown in FIG. 1 (1-2), an inlet distributor 21 is provided to disperse the raw oil (which may be liquid or gaseous) in the desulfurization reaction tower 20 as the internal structure of the reaction tower, and a distributor tray 22 is provided as necessary to further disperse the raw oil. In addition, the distributor tray 22 is provided with a manway (not shown) for various operations such as maintenance of the reaction tower below the distributor tray 22, and for filling or unloading the reaction tower filler such as a catalyst.
In the desulfurization reaction tower 20, the reactor contents are filled in layers of ceramic balls, descaling catalyst, guard catalyst, and desulfurization catalyst, in that order from the top, and the ceramic ball packed bed (upper layer) 26a, descaling catalyst packed bed 27, guard catalyst packed bed 28, desulfurization catalyst packed bed 29, and ceramic ball packed bed (lower layer) 26b are stacked in this order. Under the ceramic ball packed bed (lower layer) 26b, an outlet collector using a cylindrical wire net, a structure with slits, or the like is provided (not shown) to prevent the reactor packing forming these packed beds from flowing down. In addition, a top elbow 23 for supplying raw oil to the reaction tower is provided at the top of the desulfurization reaction tower 20, a damping nozzle 24 for extracting the catalyst, etc. by its own weight is provided at the bottom of the desulfurization reaction tower 20, and an outlet 25 for the desulfurized raw oil is provided at the bottom.

The reactor contents to be treated by the reactor contents treatment method of this embodiment include, for example, various catalysts such as desulfurization catalysts and guard catalysts, reactor fillers such as ceramic balls and descaling catalysts, which are filled in the reactors, as shown in (1-1) and (1-2) of Figure 1, as well as iron sulfide, coke-like substances, etc., which are generated due to corrosion of the reactor or the equipment upstream of it and accumulate on the catalysts in the reactor. That is, in this embodiment, the reactor contents include not only reactor fillers such as catalysts, but also deposits such as iron sulfide and coke-like substances that accumulate in the reactor due to corrosion of the equipment. Here, iron sulfide includes those that exist as scale (powder, layer, clump), as well as those that exist attached to reactor fillers such as catalysts.

As the various catalysts, preferred are catalysts used in the contact reaction of petroleum fractions and petrochemical fractions having a boiling point of -40°C to 400°C. For example, catalysts used in the contact reaction of petroleum fractions such as LPG fractions (usual boiling point -40 to 10°C), naphtha (usual boiling point about 10 to 180°C), kerosene (usual boiling point about 120 to 280°C), and diesel fractions (usual boiling point about 160 to 400°C), as well as petrochemical fractions derived from petrochemical product manufacturing equipment such as ethylene manufacturing equipment. In addition, preferred examples of catalysts used in the contact reaction include metal sulfide catalysts such as molybdenum sulfide and tungsten sulfide. Metal sulfide catalysts may generate heat, fire, and toxic gases such as sulfur-containing gases when in contact with air, and the feature of the treatment method of this embodiment of suppressing the generation of heat, fire, and toxic gases such as sulfur-containing gases can be effectively utilized. In other words, preferred examples of the reaction tower in the treatment method of this embodiment are desulfurization reaction towers in the desulfurization equipment for the above petroleum fractions.

The method for treating the contents of the reaction tower of this embodiment is characterized by spraying the hydrocarbon oil from the top of the reaction tower, and there is no need to circulate the hydrocarbon oil inside the reaction tower. Therefore, the method for treating the contents of the reaction tower of this embodiment can be applied to the treatment of the contents of a wide range of petroleum fractions and petrochemical fractions in reaction towers, such as kerosene desulfurization equipment that does not have a circulation line, and naphtha desulfurization equipment that cannot circulate inside the reaction tower because the reaction takes place in the gas phase.

The contents of the reaction tower, such as various catalysts, iron sulfide, and coke-like substances, tend to generate heat and ignite when they come into contact with air, and also tend to generate toxic gases, such as sulfur oxides and sulfur-containing gases such as hydrogen sulfide. In the method for treating the contents of the reaction tower of this embodiment, the hydrocarbon oil is sprayed from the top of the reaction tower to moisten at least the outermost layer of the contents of the reaction tower, thereby making it possible to suppress the generation of heat, ignition, and toxic gases, such as sulfur-containing gases. When the hydrocarbon oil is sprayed onto the contents of the reaction tower, the hydrocarbon first coats and moistens the outermost layer of the contents of the reaction tower, and then flows downward (in the depth direction), coating and moistening at least a portion of the contents of the reaction tower in the depth direction. It is considered that the wetting of the contents of the reaction tower by coating the hydrocarbon oil coats and moistens at least a portion of the surface of the contents of the reaction tower, while also coating and moistening at least a portion of the inside of the pores of the contents of the reaction tower. Therefore, even if air is introduced into the reaction tower from above, the area of the reaction tower contents that comes into contact with the air can be reduced, which is thought to make it possible to suppress heat generation, fire, and the generation of toxic gases such as sulfur-containing gases.

In the method for treating the contents of the reaction tower according to the present embodiment, at least the outermost layer of the contents of the reaction tower is moistened with a hydrocarbon oil. The term "moistening the outermost layer" means moistening not only the uppermost surface of the contents of the reaction tower but also the contents of the reaction tower up to a depth of at least 3 cm from the uppermost surface. The contents of the reaction tower up to a depth of 3 cm from the uppermost surface need only be moistened as a layer unit, and the entire surface of each particle of the contents of the reaction tower does not have to be moistened, but it is preferable that the entire surface is moistened from the viewpoint of suppressing heat generation, ignition, and generation of toxic gases such as sulfur-containing gases.
From the same viewpoint, when the reactor has a ceramic ball packed bed (upper layer) as shown in Figs. (1-1) and (1-2), it is preferable to wet the reactor contents below the ceramic ball packed bed (upper layer) to a depth of at least 3 cm from the top surface of the catalyst packed bed (descale catalyst packed bed in the case of the reactor shown in the figure). Since the ceramic balls in the reactor contents have almost no pores, unlike the catalyst, the hydrocarbon oil is hardly consumed to cover the ceramic balls, and most of it is considered to be consumed to cover the catalyst packed in the lower layer. Even if the hydrocarbon oil is not consumed to cover the ceramic balls, it will cover the iron sulfide and coke-like substances that are attached and accumulated on the surface of the ceramic balls and between the ceramic balls, and the ceramic balls themselves will not generate heat, fire, or toxic gases such as sulfur-containing gases, and the effect of suppressing heat, fire, and toxic gases such as sulfur-containing gases will not be hindered.

In the method for treating the reactor contents of this embodiment, as long as the outermost layer of the reactor contents is moistened, the lower layers of the reactor contents may or may not be moistened, but from the viewpoint of suppressing heat generation, ignition, and generation of toxic gases such as sulfur-containing gases, it is preferable that at least a portion of the lower layers of the reactor contents is moistened. "At least a portion is moistened" means, for example, that a portion or all of (a) a single grain unit of reactor packing such as ceramic balls, catalysts, and deposits such as iron sulfide scale and coke-like substances, or (b) a layer unit formed by packing the reactor packing in layers is moistened.

In the above (a), only partially wetted particles may exist in a single particle unit, only fully wetted particles may exist, or partially wetted and fully wetted particles may exist. In the above (b), the reaction tower contents are wetted to the lowest depth where at least partially wetted particles exist in a single particle unit. In (b), deposits such as iron sulfide and coke-like substances are present in the packed bed of the reaction tower packing such as ceramic balls and catalysts by deposition, etc., so that if at least a part of the packed bed is wetted, at least a part of the packed bed will be wetted automatically.
In this embodiment, in any of the above aspects, the surface area of the reaction tower contents in contact with air is reduced, making it possible to suppress heat generation, ignition, and generation of toxic gases such as sulfur-containing gases.

The depth of wetting cannot be generally determined because it depends on the size of the reaction tower, but from the viewpoint of obtaining a better effect of suppressing heat generation, ignition, and generation of toxic gases such as sulfur-containing gases, it is preferable to wet to a depth of, for example, preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 15 cm or more from the top surface of the reaction tower contents. In addition, the upper limit of the depth may be up to the bottom layer of the reaction tower contents, that is, all of the reaction tower contents may be wetted, but from the viewpoint of more efficiently suppressing heat generation, ignition, and generation of toxic gases such as sulfur-containing gases, taking into consideration the amount of hydrocarbon oil used, etc., it is preferably 80 cm or less, more preferably 70 cm or less, and even more preferably 50 cm or less from the top surface of the reaction tower contents. From the same viewpoint, in the case of having a ceramic ball packed layer (upper layer) as shown in Figures (1-1) and (1-2), it is preferable to wet to a depth in the above range from the top surface of the catalyst packed layer (descale catalyst packed layer in the case of the reaction tower shown in the figure) below the ceramic ball packed layer (upper layer).
In addition, in the case of a reaction tower having an internal structure as shown in FIG. 1 (1-1), it is preferable to set the depth above from the bottom surface of the internal structure (scale basket) in consideration of removing the internal structure.

The method of spraying the hydrocarbon oil is not particularly limited as long as the hydrocarbon oil can be sprayed so as to cover the contents of the reaction tower, and preferred examples include a method of spraying using a distributor tray, which is an internal structure of the reaction tower, a method of spraying using a tool such as a hose or a nozzle, etc. The hydrocarbon oil may be sprayed in multiple batches, and when the contents of the reaction tower that are not wetted are exposed during work inside the reaction tower, such as removal of the internal structure of the reaction tower, additional hydrocarbon oil may be sprayed.
Considering the efficiency of the work of removing the reactor internal structure after the hydrocarbon oil is sprayed, a method of spraying using a tool such as a hose or a nozzle after removing the inlet distributor installed at the inlet of the raw oil is preferred, and in a reactor in which a distributor tray is provided as the reactor internal structure, a method of spraying using the distributor tray is preferred. When a distributor tray is provided in the reactor, iron sulfide, coke-like substances, etc. may be deposited on the tray, so spraying using this makes it possible to wet not only the reactor contents but also the iron sulfide, coke-like substances, etc. deposited on the tray.

From the viewpoint of suppressing heat generation, ignition, and the generation of toxic gases such as sulfur-containing gases, it is preferable to spray the hydrocarbon oil in an inert gas atmosphere such as nitrogen inside the reaction tower. In this case, the inert gas such as nitrogen may be supplied into the reaction tower from a nozzle for purging the inside of the reaction tower at the bottom of the reaction tower, or may be supplied from the top of the reaction tower. In other words, it is preferable to spray the hydrocarbon oil while supplying an inert gas such as nitrogen into the reaction tower.

In this embodiment, the hydrocarbon oil is sprayed from the top of the reaction tower using a simple tool such as a hose, or a structure already installed inside the reaction tower. Therefore, the method for treating the contents of the reaction tower of this embodiment can be applied to a wide range of petroleum fraction and petrochemical fraction reaction towers regardless of the presence or absence of a line for circulating the hydrocarbon oil, the gas-liquid state of the feed oil in the reaction tower during operation, etc., and it becomes possible to easily treat the contents of the reaction tower. In addition, in any of the above methods, the operator does not enter the reaction tower, but can perform the work from the outside, so the work is highly safe even if the reaction tower is filled with an inert gas atmosphere such as nitrogen.

In this embodiment, from the viewpoint of more easily and efficiently suppressing heat generation, ignition, and the generation of toxic gases such as sulfur-containing gases, it is preferable to wet at least a portion of the upper layer of the reaction tower packing from the surface in the depth direction. By wetting in this manner, deposits such as iron sulfide and coke-like substances that tend to accumulate in the upper layers of the reaction tower packing can also be wetted at the same time, making it possible to more efficiently suppress heat generation, ignition, and the generation of toxic gases such as sulfur-containing gases.

In this embodiment, the volume of the reaction tower contents is not particularly limited, but from the viewpoint of more easily and efficiently suppressing heat generation, ignition, and generation of toxic gases such as sulfur-containing gases, it is preferably 0.5 m ³ or more, more preferably 1 m ³ or more. The upper limit of the volume of the reaction tower contents is preferably 100 m ³ or less, more preferably 90 m ³ or less. In the wetting of the reaction tower contents by the treatment method of this embodiment, some of the reaction tower contents may not be wetted, and it may be necessary to recover the reaction tower contents using a drum can rather than a simple container such as a flexible container bag. However, if the volume is 100 m ³ or less, it is easier to recover the reaction tower contents using a drum can with less burden. In addition, the dispersion of hydrocarbon oil is also easier.

The hydrocarbon oil used in the method for treating the contents of a reaction column according to this embodiment may be either a mineral oil or a synthetic oil.
Examples of such mineral oils include atmospheric residual oils obtained by atmospheric distillation of paraffinic, naphthenic, or intermediate crude oils; distillate oils obtained by vacuum distillation of such atmospheric residual oils; and mineral oils obtained by refining such distillate oils through one or more of the following processes: solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc., such as light neutral oil, medium neutral oil, heavy neutral oil, and bright stock, as well as mineral oils obtained by isomerizing wax produced by the Fischer-Tropsch process or the like (GTL wax).
Examples of synthetic oils include various ester oils such as polyol esters, dibasic acid esters, and phosphate esters; various ethers such as polyphenyl ether; and polyglycols.

In this embodiment, the hydrocarbon oil may be at least one type of mineral oil, at least one type of synthetic oil, or a mixed oil of at least one type of mineral oil and at least one type of synthetic oil. In this embodiment, the hydrocarbon oil is preferably a mineral oil, and paraffin-based mineral oil is particularly preferred. Mineral oil is inexpensive, easy to handle, and can more easily moisten the contents of the reaction tower, making it easier to suppress heat generation, fire, and the generation of toxic gases such as sulfur-containing gases.

The properties of the hydrocarbon oil used in the treatment method of this embodiment preferably include at least the flash point, kinematic viscosity at 40° C., viscosity index, sulfur content, and aromatic content within the following ranges.
The flash point is not particularly limited as long as it is a temperature higher than the temperature inside the reaction tower at the time of spraying, but for example, 100° C. or higher is preferable, 120° C. or higher is more preferable, and 140° C. or higher is even more preferable. If the flash point is as high as 100° C. or higher, handling is easy and safety is high. Here, the flash point is a value measured in accordance with JIS K 2265-4:2007 (Method of Determining Flash Point, Part 4: Cleveland Open Method).

The 40°C kinetic viscosity is preferably 2.0 ^mm2 /s or more, more preferably 4.0 ^mm2 /s or more, and even more preferably 6.0 ^mm2 /s or more, with the upper limit being preferably 60.0 ^mm2 /s or less, more preferably 50.0 ^mm2 /s or less, and even more preferably 40.0 ^mm2 /s or less. When the 40°C kinetic viscosity is 2.0 ^mm2 /s or more, the moistening state of the reaction tower contents becomes more stable. Also, when the 40°C kinetic viscosity is 60.0 ^mm2 /s or less, the moistening of the reaction tower contents can be more easily performed.
The viscosity index is preferably 75 or more, more preferably 80 or more, and the upper limit is preferably 120 or less, more preferably 110 or less. When the viscosity index is within the above range, the property stability of the hydrocarbon oil is high, and wetting can be performed more reliably.
Here, the 40° C. kinematic viscosity and viscosity index, as well as the 100° C. kinematic viscosity described below, are values measured in accordance with JIS K 2283:2000 (Crude oil and petroleum products -- Test method for kinematic viscosity and calculation method for viscosity index).

The lower the sulfur content, the better from the viewpoint of further suppressing contamination inside the reaction tower, and it is preferably 500 ppm by mass or less, more preferably 300 ppm by mass or less, even more preferably 100 ppm by mass or less, and particularly preferably 10 ppm by mass or less (sulfur-free). Here, the sulfur content is a value measured in accordance with JIS K2541-6:2003 (Crude oil and petroleum products - Sulfur content test method - Part 5: Ultraviolet fluorescence method).

The aromatic content is preferably 10% or less, more preferably 5% or less, and even more preferably 2% or less, as %C _A of ring analysis (nd-M method). The lower the lower limit, the better, and it is particularly preferable that aromatic content is not contained. When %C _A is within the above range, safety is particularly improved. Here, the ring analysis (nd-M method) is a value measured in accordance with ASTM D3238-85.

As described above, the hydrocarbon oil used in the treatment method of this embodiment preferably has a flash point of 100° C. or higher, a 40° C. kinetic viscosity of 2.0 mm ² /s to 60.0 mm ² /s, a viscosity index of 75 to 120, a sulfur content of 500 mass ppm or lower, and an aromatic content (% C _A ) of 10% or lower. By using a hydrocarbon oil having such properties, the reaction tower contents can be moistened more reliably and efficiently, and the moistened state of the reaction tower contents can be made more stable.
The hydrocarbon oil used in the treatment method of this embodiment may have the following properties in addition to the above properties, namely, the following 100°C kinematic viscosity, pour point, naphthene content, and paraffin content properties.

The 100°C kinetic viscosity is preferably 1.0 ^mm2 /s or more, more preferably 1.5 ^mm2 /s or more, and even more preferably 2.0 ^mm2 /s or more, and the upper limit is preferably 10.0 ^mm2 /s or less, more preferably 9.0 ^mm2 /s or less, and even more preferably 8.0 ^mm2 /s or less. When the 100°C kinetic viscosity is 1.0 ^mm2 /s or more, the moistened state of the reaction tower contents becomes more stable, and when it is 10.0 ^mm2 /s or less, the reaction tower contents can be moistened more easily.
The 40° C. kinematic viscosity and the 100° C. kinematic viscosity of the hydrocarbon oil are preferably within the above ranges at the same time. By simultaneously being within the above ranges, it becomes possible to more easily wet the contents of the reaction column under a wider range of temperature conditions.

The pour point is preferably 0.0° C. or lower, more preferably −2.5° C. or lower, and even more preferably −7.5° C. or lower, and the lower limit is preferably −30.0° C. or higher, more preferably −25.0° C. or higher, and even more preferably −20.0° C. or higher. When the pour point is within the above range, the moistened state of the reaction tower contents becomes more stable, and the moistening of the reaction tower contents can be more easily performed.
The pour point here is a value measured in accordance with JIS K 2269:1987 (Testing method for pour point and cloud point of crude oil and petroleum products).

From the viewpoint of facilitating wetting of the reaction column contents, the naphthene content is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more in terms of % C _N by ring analysis (nd-M method), with the upper limit being preferably 50% or less, more preferably 45% or less. From the same viewpoint, the paraffin content is preferably 50% or more, more preferably 53% or more in terms of % C _P by ring analysis (nd-M method), with the upper limit being preferably 75% or less, more preferably 70% or less.

The amount of the hydrocarbon oil to be sprayed is not particularly limited, but from the viewpoint of more reliably and efficiently obtaining a better wetting state of the reaction tower contents, in the packed section in the reaction tower where the reaction tower contents are packed, the amount is preferably 50 L or more, more preferably 100 L or more, even more preferably 200 L or more, still more preferably 250 L or more per 1 ^m3 of the volume corresponding to the depth of the packed section to be wetted, and the upper limit is preferably 1000 L or less, more preferably 800 L or less, even more preferably 500 L or less, still more preferably 400 L or less.

The temperature inside the reaction tower when wetting the contents of the reaction tower (wetting temperature) may be adjusted appropriately depending on the type of hydrocarbon oil used from the viewpoint of efficiently wetting the contents of the reaction tower with the viscosity of the hydrocarbon oil in an appropriate range, but the temperature inside the reaction tower is usually preferably 10°C or higher, more preferably 15°C or higher, and even more preferably 20°C or higher, with the upper limit being preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower. In addition, if the temperature of the hydrocarbon oil is within the above range, the temperature inside the reaction tower becomes moderate, and the efficiency of subsequent work such as removing the internal structures of the reaction tower is improved. In addition, the temperature during the removal of the internal structures of the reaction tower is preferably 50°C or lower, more preferably 45°C or lower, and even more preferably 40°C or lower from a safety standpoint.

The time for which the reactor contents are left to stand after the hydrocarbon oil is sprayed on them (wetting time) is preferably 10 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and even more preferably 2 hours or more, with the upper limit being preferably 12 hours or less, more preferably 6 hours or less, and even more preferably 4 hours or less, from the viewpoint of more reliably and efficiently obtaining a better wetting state of the reactor contents.

In addition to the wetting step described above, the method for treating the contents of the reaction tower in this embodiment may also include, for example, a preparatory step for the wetting step, such as a step of adjusting conditions inside the reaction tower to lower the temperature and pressure inside the reaction tower in order to spray the hydrocarbon oil more safely, an inert gas introduction step of introducing an inert gas such as nitrogen into the reaction tower, and a removal step of removing the top elbow connected to the raw oil supply port at the top of the reaction tower and, if necessary, the inlet distributor.

The method for treating the contents of the reaction tower of this embodiment is applicable to reaction towers for a wide range of petroleum fractions, petrochemical fractions, etc., and is a treatment method that can easily suppress the generation of heat, fire, and toxic gases such as sulfur-containing gases. Therefore, the method for treating the contents of the reaction tower of this embodiment is suitable for use in reaction towers used for contact reactions of petroleum fractions and petrochemical fractions with boiling points of -40°C to 400°C. More specifically, it is suitable for use in reaction towers used for contact reactions of petroleum fractions such as LPG fractions, light oil fractions, naphtha, and kerosene, and petrochemical fractions derived from petroleum fractions such as ethylene production equipment, and in particular, it is suitable for use in desulfurization reaction towers, which are reaction towers equipped with catalysts, such as metal sulfide catalysts, that can generate heat, fire, and toxic gases such as sulfur-containing gases when the reaction tower contents come into contact with air. By adopting the treatment method of this embodiment to such a reaction tower, it becomes possible to safely introduce air into the reaction tower, and various maintenance operations inside the reaction tower, such as maintenance and removal of the internal structures of the reaction tower, removal of the catalyst and other contents of the reaction tower, and filling operations can be performed more safely.

[Method of withdrawing the contents of the reaction tower]
The method for extracting the contents of a reaction tower of this embodiment is characterized by having the moistening step in the method for treating the contents of a reaction tower of this embodiment, the step of introducing air into the reaction tower from the top and removing the internal structure of the reaction tower, and the step of extracting the contents of the reaction tower. The method for extracting the contents of a reaction tower of this embodiment has the moistening step, which makes it possible to safely introduce air into the reaction tower from the top, and therefore makes it possible to more safely and efficiently proceed with the subsequent steps, i.e., the step of removing the internal structure of the reaction tower and the step of extracting the contents of the reaction tower.

In the method for extracting the contents of a reaction tower of this embodiment, the wetting step, the internal structure of the reaction tower, and the contents of the reaction tower are the same as those described in the method for treating the contents of a reaction tower of this embodiment.
An example of the reaction tower internal structure to be removed in the process of removing the reaction tower internal structure is a scale basket. The scale basket is arranged in a bundled form without a support jig on the packed bed of the reaction tower packing such as a catalyst, and therefore, when the reaction tower contents are removed from the damping nozzle at the bottom of the reaction tower by their own weight, the scale basket follows the reaction tower contents and descends to the vicinity of the damping nozzle inlet, which may cause clogging. Therefore, in a reaction tower in which a scale basket is arranged, it is preferable to remove the scale basket before removing the reaction tower contents. In addition, the inlet distributor, the manway of the distributor tray, and the like may also be removed as necessary.

At the time of the process of removing the internal structure of the reaction tower, the contents of the reaction tower are already moistened, so even if air is introduced into the reaction tower, it is possible to suppress the generation of heat, fire, and toxic gases such as sulfur-containing gases. Therefore, the process of removing the internal structure of the reaction tower can be performed in an air atmosphere inside the reaction tower, so workers can safely remove the internal structure of the reaction tower. However, for dust prevention measures and for greater safety considerations, it is preferable for workers to wear airline masks during the process of removing the internal structure of the reaction tower.

The contents of the reaction tower are preferably removed by gravity from a damping nozzle installed at the bottom of the reaction tower, as this is easy and efficient, and is also preferably performed after removing the internal structure of the reaction tower. If the reaction tower has an internal structure of the reaction tower, such as a scale basket, that is placed on the reaction tower packing without a support jig, and the contents of the reaction tower are removed by gravity from the damping nozzle at the bottom of the reaction tower, the internal structure of the reaction tower will follow the contents of the reaction tower and descend near the inlet of the damping nozzle, causing a blockage and preventing the contents of the reaction tower from being quickly removed. The contents of the reaction tower can also be removed by vacuum extraction from the top of the reaction tower, and can be combined as appropriate.

When the reactor contents are removed by gravity from the dumping nozzle installed at the bottom of the reactor as described above, the reactor contents may remain at the bottom below the bottom of the reactor. In this case, after spraying an appropriate amount of hydrocarbon oil from the top of the reactor, an operator can enter the reactor and remove the contents, or perform vacuum removal.

The removed reactor contents may contain unmoisturized material, so from a safety standpoint, it is preferable to collect the contents in a drum. If all of the reactor contents have been moistened, they may be collected in a simple container such as a flexible container bag.

The method for extracting the contents of the reaction tower of this embodiment includes the wetting step in the method for treating the contents of the reaction tower of this embodiment described above, and by wetting the reaction tower contents, such as the reaction tower fillers such as catalysts, and the deposits of iron sulfide and coke-like substances, the generation of heat, ignition, and toxic gases such as sulfur-containing gases can be suppressed, making it possible to safely and efficiently extract the contents of the reaction tower. Therefore, the method for extracting the contents of the reaction tower of this embodiment is suitable for extracting the contents of a reaction tower used in the contact reaction of petroleum fractions and petrochemical fractions having a boiling point of -40°C to 400°C. More specifically, it is suitable for extracting the contents of a reaction tower used in the contact reaction of petroleum fractions such as LPG fractions, light oil fractions, naphtha, and kerosene, and petrochemical fractions derived from petrochemical product manufacturing equipment such as ethylene manufacturing equipment, and in particular, it is suitable for extracting the contents of a desulfurization reaction tower, which is a reaction tower equipped with a catalyst, such as a metal sulfide catalyst, that can generate heat, ignition, and toxic gases such as sulfur-containing gases when the reaction tower contents come into contact with air. By adopting the extraction method of this embodiment to extract the contents of such a reaction tower, it becomes possible to introduce air into the reaction tower during various operations such as maintenance inside the reaction tower, such as various operations such as maintenance and removal of the internal structure of the reaction tower, and during operations such as extracting the catalyst and other contents of the reaction tower, thereby providing a safer working environment for workers.

[Hydrocarbon oil]
The hydrocarbon oil of this embodiment has a flash point of 100° C. or higher, a 40° C. kinetic viscosity of 2.0 mm ² /s to 60.0 mm ² /s, a viscosity index of 75 to 120, a sulfur content of 500 mass ppm or lower, and an aromatic content (% C _A ) of 10% or lower, and is used for wetting the contents of a reaction tower. When the hydrocarbon oil has such properties, the wetting of the contents of the reaction tower can be performed more reliably and efficiently, and the wetting state of the contents of the reaction tower can be more stabilized.
The type and properties of the hydrocarbon oil are the same as those of the hydrocarbon oil described above as being usable in the wetting step in the method for treating the contents of a reaction tower of this embodiment.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

(Measurement of Hydrocarbon Oil Properties)
The properties of the hydrocarbon oils used in each of the Examples and Comparative Examples were measured by the following methods.
(1) Flash point: Measured in accordance with JIS K 2265-4:2007 (Part 4: Cleveland Open Method).
(2) Kinematic viscosity and viscosity index: Measured in accordance with JIS K 2283:2000.
(3) Pour point: Measured in accordance with JIS K 2269:1987.
(4) Sulfur content: Measured in accordance with JIS K2541-6:2003 (Part 6: Ultraviolet fluorescence method).
(5) Aromatic content, naphthene content and paraffin content: %C _A , %C _N and %C _P measured by ring analysis (ndM method) in accordance with ASTM D3238-85 were taken as the aromatic content, naphthene content and paraffin content, respectively.

The properties of the hydrocarbon oils (hydrocarbon oils 1 and 2) used in each example and comparative example, measured by the above method, are shown in Table 1 below.

Example 1
After the naphtha desulfurization equipment was shut down, the temperature of the desulfurization reaction tower in the equipment (see FIG. 1 (1-1), reaction tower packing (catalyst) volume: 20 ^m3 ) was lowered to 40°C, and nitrogen was introduced from the bottom nozzle of the reaction tower. Then, the top elbow and inlet distributor connected to the top of the reaction tower were removed to open the top of the reaction tower, and nitrogen was introduced from the top of the reaction tower using a hose. Next, hydrocarbon oil 1 (paraffinic mineral oil) having the properties shown in Table 1 was sprayed using a hose. The spraying range was from the top of the catalyst packed bed (top of the descaling catalyst packed bed) of the reaction tower packing to a depth of 500 mm, and the amount of sprayed was 300 L per ^m3 of the volume (3.3 ^m3 ) of the 500 mm depth, that is, 990 L of hydrocarbon oil was sprayed.
Two hours after the end of the spraying of the hydrocarbon oil, the wetting of the reaction tower contents (ceramic balls, catalyst, iron sulfide and coke-like substances) was deemed to be complete, and the introduction of nitrogen from the bottom nozzle of the reaction tower was stopped, the nitrogen introduction line was cut off, and the introduction of nitrogen from the top of the reaction tower was also stopped by removing the hose, and the nitrogen line to the reaction tower was completely blocked. Next, the introduction of air was started from the top of the reaction tower using another hose, and the oxygen concentration in the top of the reaction tower reached 21% by volume. After confirming with a gas detector that no sulfur oxides such as sulfur dioxide and sulfur trioxide, sulfur-containing gases such as hydrogen sulfide, or toxic gases such as carbon monoxide were generated, and that the temperature inside the reaction tower was 40°C, a worker wearing an airline mask entered the tank and removed the scale basket installed at the top of the reaction tower. Then, the reaction tower contents were extracted by their own weight from a dumping nozzle installed at the bottom of the reaction tower, and the used catalyst and the like were extracted and collected in a drum. The contents remaining at the bottom of the reactor were moistened by spraying hydrocarbon oil from the top of the reactor again, and then workers entered the reactor under air and collected them in drums. When the workers worked inside the reactor, the atmosphere was air, so the workers could work safely and with peace of mind. Although they were wearing airline masks, they were able to work safely and efficiently.

Example 2
After the operation of the kerosene desulfurization apparatus was stopped, the temperature of the desulfurization reaction tower in the apparatus (see (1-2) in Figure 1, reaction tower packing (catalyst) volume: 33 ^m3 ) was lowered to 60°C and nitrogen was introduced from the lower nozzle of the reaction tower. Then, the top elbow and inlet distributor connected to the upper part of the reaction tower were removed to open the upper part of the reaction tower, and nitrogen was introduced from the upper part of the reaction tower using a hose. Next, hydrocarbon oil 2 (paraffinic mineral oil) having the properties shown in Table 1 was supplied to the distributor tray using a hose and sprayed over the contents of the reaction tower using the distributor tray. The spraying range was from the top surface of the catalyst packed bed (the top surface of the descaling catalyst packed bed) of the reaction tower packing to a depth of 500 mm, and the spraying amount was 300 L (900 L) per ^m3 of the volume of the 500 mm depth (3.0 ^m3 ) plus 1200 L remaining on the distributor tray, totaling 2100 L of hydrocarbon oil sprayed (the amount of hydrocarbon oil sprayed onto the catalyst packed bed was essentially 900 L).
Two hours after the end of the spraying of the hydrocarbon oil, the wetting of the reaction tower contents (ceramic balls, catalyst, iron sulfide, and coke-like substances) was deemed to be complete, and the introduction of nitrogen from the nozzle at the bottom of the reaction tower was stopped, the nitrogen introduction line was cut off, and the introduction of nitrogen from the top of the reaction tower was also stopped by removing the hose, and the nitrogen line to the reaction tower was completely blocked. Next, the introduction of air was started from the top of the reaction tower using another hose, and the oxygen concentration in the top of the reaction tower reached 21% by volume, and after confirming with a gas detector that no sulfur oxides such as sulfur dioxide and sulfur trioxide, sulfur-containing gases such as hydrogen sulfide, or toxic gases such as carbon monoxide were generated, and the temperature inside the reaction tower was 40°C, a worker wearing an airline mask entered the tank and recovered the hydrocarbon oil, iron sulfide, and coke-like substances remaining on the distributor tray installed at the top of the reaction tower, and then the manway of the distributor tray was removed. After that, the reactor contents were extracted under their own weight through a dumping nozzle installed at the bottom of the reactor, and the used catalyst, etc. were extracted and collected in a drum. The reactor contents remaining at the bottom of the reactor were moistened again by spraying hydrocarbon oil from the top of the reactor, and then workers entered the reactor under air atmosphere and collected the contents in a drum. When the workers worked inside the reactor, the atmosphere was air, so the workers could work safely and with peace of mind, and they were able to work safely and efficiently, even though they were wearing airline masks.

(Comparative Example 1)
After the naphtha desulfurization equipment was shut down, the temperature of the desulfurization reaction tower in the equipment was lowered to 60°C, nitrogen was introduced from the bottom nozzle of the reaction tower, and then the top elbow and inlet distributor connected to the top of the reaction tower were removed to open the top of the reaction tower, and nitrogen was introduced from the top of the reaction tower using a hose. After confirming that the temperature inside the reaction tower was 40°C, a worker wearing an airline mask entered the tank and removed the scale basket installed at the top of the reaction tower. Although the worker was wearing an airline mask, the inside of the reaction tower was in a nitrogen atmosphere, and if a problem such as the airline mask came off during work occurred, the worker would be in an oxygen-deficient state, so he could not work safely and with peace of mind, and he could not work safely and efficiently.

10. Desulfurization reaction tower in naphtha desulfurization unit 11. Inlet distributor 12. Scale basket 13. Top elbow 14. Damping nozzle 15. Discharge port 16. Ceramic ball packed bed 16a. Ceramic ball packed bed (upper layer)
16b. Ceramic ball packed layer (lower layer)
17. Descaling catalyst packed bed 18. Guard catalyst packed bed 19. Desulfurization catalyst packed bed 20. Desulfurization reaction tower in kerosene desulfurization equipment 21. Inlet distributor 22. Distributor tray 23. Top elbow 24. Damping nozzle 25. Discharge port 26. Ceramic ball packed bed 26a. Ceramic ball packed bed (upper layer)
26b. Ceramic ball packed layer (lower layer)
27. Descaling catalyst packed bed 28. Guard catalyst packed bed 29. Desulfurization catalyst packed bed

Claims (12)

A method for treating the contents of a reaction tower, comprising a wetting step of spraying a hydrocarbon oil from the upper part of the reaction tower to wet at least a part of the outermost layer of the contents of the reaction tower before air is introduced into the reaction tower from the upper part, wherein the naphthene content (% C _N ) of the hydrocarbon oil is 10% or more and 50% or less and the aromatic content (% C _A ) is 10% or less as determined by ring analysis (ndM method) of the hydrocarbon oil, and the amount of the hydrocarbon oil sprayed is 50 L ^or more and 1000 L or less per m3 of a volume corresponding to the depth of the packed section to be wetted in the packed section where the contents of the reaction tower are packed. 2. The method for treating the contents of a reaction tower according to claim 1, wherein the hydrocarbon oil has a flash point of 100°C or higher, a kinematic viscosity at 40°C of 2.0 ^mm2 /s or higher and 60.0 ^mm2 /s or lower, a viscosity index of 75 or higher and 120 or lower, a sulfur content of 500 mass ppm or lower, and an aromatic content (% C _A ) of 10% or lower. The method for treating the contents of a reaction tower according to claim 1 or 2, in which the hydrocarbon oil is dispersed using a distributor tray. The method for treating the contents of a reaction tower according to claim 1 or 2, wherein the hydrocarbon oil is sprayed using at least one tool selected from a hose and a nozzle. The method for treating the contents of a reaction tower according to any one of claims 1 to 4, wherein the contents of the reaction tower are at least one selected from a catalyst used in the contact reaction of petroleum fractions and petrochemical fractions having a boiling point of -40°C or more and 400°C or less, iron sulfide, and a coke-like substance. The method for treating the contents of a reaction tower according to claim 5, wherein the petroleum fraction is at least one selected from the group consisting of an LPG fraction, a light oil fraction, naphtha, and kerosene. The method for treating the contents of a reaction tower according to any one of claims 1 to 6, wherein the temperature inside the reaction tower is 10°C or higher and 80°C or lower. The method for treating the contents of a reaction tower according to any one of claims 1 to 7, wherein the volume of the contents of the reaction tower is 0.5 ^m3 or more and 100 ^m3 or less. A method for removing the contents of a reaction tower comprising a wetting step in the method for treating the contents of a reaction tower according to any one of claims 1 to 8, a step of introducing air into the reaction tower from the top and removing the internal structure of the reaction tower, and a step of removing the contents of the reaction tower. The method for extracting the contents of a reaction tower according to claim 9, wherein the reaction tower internal structure is at least one structure selected from an inlet distributor, a scale basket, and a manway of a distributor tray. 9. A hydrocarbon oil used in the method for treating the contents of a reaction tower according to any one of claims 1 to 8, which has a flash point of 100°C or higher, a 40°C kinematic viscosity of ^2.0 to 60.0 ^mm2 /s, a viscosity index of 75 to 120 , a sulfur content of 500 mass ppm or lower, and a naphthene content (% C _N ) of 10 to 50% and an aromatic content (% C _A ) of 10% or lower, as determined by ring analysis (ndM method ). The hydrocarbon oil according to claim 11, wherein the reaction tower contents are at least one selected from a catalyst used in the contact reaction of petroleum fractions and petrochemical fractions having a boiling point of -40°C or higher and 400°C or lower, and iron sulfide.