Distillation method

Abstract

To provide a distillation method that refines a chemical product by supplying two or more kinds of distillates with different boiling point ranges to a distillation column and distilling them therein and that can reduce necessary energy and enables stable operation.SOLUTION: A distillation method refines a chemical product by supplying two or more kinds of distillates D1-Dn with different boiling point ranges (n is an integer equal to or greater than two and indicates a kind of distillate, where a smaller n indicates a distillate with a lower boiling point range) to different supply ports S1- Sn of a distillation column (n is the same as above, indicating the supply ports corresponding to the distillates D1-Dn) and distilling them. A mixed distillate produced by mixing a portion of one distillate Dp among the distillates D1-Dn with another distillate Dq is supplied to a supply port Sq.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a distillation method.

Background Art

[0002] Distillation is an operation that separates a target substance from a mixture by utilizing the difference in vapor pressure of liquids. Distillation is widely used in chemical industries in processes such as purification, separation, and recovery.

[0003] For example, in the crude oil refining process for producing petroleum products, distillation is very important. First, the crude oil is subjected to atmospheric distillation in an atmospheric distillation unit and separated into fractions such as off-gas, LPG, straight-run naphtha, straight-run kerosene, straight-run gas oil, and atmospheric distillation residue oil. These fractions are further refined through processes such as desulfurization and distillation to produce petroleum products.

[0004] Patent Document 1 discloses a method for purifying hydrocarbon oil, which is characterized by subjecting straight-run gas oil obtained by subjecting crude oil to atmospheric distillation in an atmospheric distillation unit to a hydrogenation treatment (desulfurization treatment) using a hydrodesulfurization catalyst having a specific structure.

[0005] Since the hydrocarbon oil (desulfurized straight-run gas oil) obtained by the method described in Patent Document 1 contains a naphtha fraction, gas, etc., light oil, which is a petroleum product, is produced through further refining processes.

[0006] Specifically, the desulfurized straight-run gas oil is supplied to a distillation column, distilled, and separated into a light fraction and a heavy fraction. The light fraction is mixed with the heavy fraction after separating the gas contained in the light fraction to form a mixed fraction. The mixed fraction is supplied to a distillation column and distilled again. A naphtha fraction, gas, etc. are discharged from the top of the distillation column, and light oil, which is a petroleum product, is produced from the bottom of the distillation column (hereinafter, this purification method is also referred to as "Purification Method 1").

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] For example, diesel fuel, a petroleum product, is required to have a high flash point. The flash point of diesel fuel is related to the naphtha fraction content; diesel fuel with a low naphtha fraction content has a higher flash point. In other words, in order to obtain diesel fuel with a high flash point, the separation of the naphtha fraction in the second distillation step of refining method 1 is important. One known method for sufficiently separating the naphtha fraction is to introduce steam from the bottom of the column to lower the partial pressure of the fraction in the distillation column, thereby promoting the distillation of the naphtha fraction.

[0009] The inventors of the present invention have investigated improvements to purification method 1 with the aim of reducing the amount of steam supplied, from the viewpoint of energy reduction. Specifically, they investigated a purification method (hereinafter also referred to as "purification method 2") in which the light fraction and the heavy fraction, after the separation of the gas, are supplied to the distillation column from separate inlets of the distillation column without mixing, and distillation is performed. In purification method 2, the light fraction is supplied to the distillation column from the inlet on the top side of the distillation column, and the heavy fraction is supplied from the inlet on the bottom side of the distillation column.

[0010] As a result, it was found that refining method 2 makes it possible to produce diesel fuel with a similar flash point even with a reduced steam supply compared to refining method 1. On the other hand, it was also found that refining method 2 resulted in a lower temperature near the top of the distillation column compared to refining method 1.

[0011] In distillation columns used in the crude oil refining process, the temperature near the top of the column is controlled to remain above the dew point to prevent corrosion. This is because near the top of the column, salts in the distilled fraction can decompose, generating hydrogen chloride gas. If liquid water is present near the top of the column, this gas can become highly corrosive hydrochloric acid, which corrodes the column. The inventors of this invention found that when they continued operating refining method 2, the temperature near the top of the column fell below the dew point, making stable operation difficult. In other words, although refining method 2 can reduce energy consumption compared to refining method 1, stable operation is difficult.

[0012] Similar problems are likely to occur in distillation columns used in processes other than crude oil refining, as long as water is present inside the column and the refining process is such that corrosion and other problems can arise due to the generation of condensed water.

[0013] This application was made in view of the above circumstances, and aims to provide a distillation method that reduces the required energy and enables stable operation in a distillation method for purifying chemical products by supplying two or more fractions with different boiling point ranges to a distillation column and distilling them. [Means for solving the problem]

[0014] To solve the above problems, the present invention has the following embodiments. [1] Two or more fractions D1-D with different boiling point ranges n (n is an integer greater than or equal to 2, indicating the type of fraction; a smaller n indicates a fraction with a lower boiling point range) These represent different feed ports S1~S of the distillation column. n (n is the same as above, and the fractions D1~D n A distillation method for purifying a chemical by supplying it to a supply port corresponding to (showing) and distilling, wherein the fractions D1 to D n One of the fractions D p A portion of it, and the other fraction D q The mixed fraction obtained by mixing is supplied to the supply port S q A distillation method for supplying to a supplier. [2] The supply ports S1~Sn is the distillation method according to [1], which is located in order from the top to the bottom of the distillation column. [3] The fraction D p has a boiling point range lower than that of the other one fraction D q in the distillation method according to [1] or [2]. [4] The fraction D q when the flow rate [kL / h] of the fraction D is taken as 100%, the ratio of the flow rate [kL / h] of the fraction D p is 2 to 15% in the distillation method according to any one of [1] to [3]. [5] The fraction D p when the flow rate [kL / h] of the fraction D is taken as 100%, the fraction D q to be mixed into the fraction D p when the flow rate [kL / h] of the fraction D is taken as 100%, the ratio of the flow rate [kL / h] of the fraction D [6] The fraction D q when the flow rate [kL / h] of the fraction D is taken as 100%, the fraction D q to be mixed into the fraction D p when the flow rate [kL / h] of the fraction D is taken as 100%, the ratio of the flow rate [kL / h] of the fraction D [7] The fraction D1 to D n when the total flow rate [kL / h] of the fraction D1 to D is taken as 100%, the fraction D p supplied to the supply port S p when the flow rate [kL / h] of the fraction D is taken as 100%, the ratio of the flow rate [kL / h] of the fraction D [8] The fraction D p is the fraction D1 in the distillation method according to any one of [1] to [7]. [9] n is 2 or more and 7 or less in the distillation method according to any one of [1] to [8].

[10] n is 2 in the distillation method according to [9].

[11] The chemical is a petroleum base material in the distillation method according to any one of [1] to

[10] .

[12] The petroleum base material is light oil or kerosene in the distillation method according to

[11] . [Advantages of the Invention]

[0015] According to the present invention, in a distillation method for purifying a chemical product by supplying two or more fractions with different boiling point ranges to a distillation column and distilling them, it is possible to provide a distillation method that can reduce the required energy and enable stable operation. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing an example of a distillation apparatus for carrying out the distillation method of this embodiment. [Figure 2] This is a schematic diagram showing an example of manufacturing equipment for carrying out a method of manufacturing light oil or kerosene. [Modes for carrying out the invention]

[0017] The embodiments of the present invention will be described in detail below, but the following description is merely one example of an embodiment of the present invention, and the present invention is not limited to these contents and can be modified and implemented within the scope of its gist.

[0018] ≪Distillation Method≫ The distillation method of this embodiment involves two or more fractions D1 to D with different boiling point ranges. n (n is an integer greater than or equal to 2, indicating the type of fraction; a smaller n indicates a fraction with a lower boiling point range) These represent different feed ports S1~S of the distillation column. n (n is the same as above, and the fractions D1~D n This is a distillation method in which chemicals are purified by supplying them to a supply port (which corresponds to) and distilling them. The fractions D1 to D n One of the fractions D p A portion of it, and the other fraction D q The mixed fraction obtained by mixing is supplied to the supply port S q To supply.

[0019] Dilution D p The boiling point range of the other fraction D qIt is preferable that the boiling point range is lower than the boiling point range of the fraction. In this specification, the boiling point ranges of multiple fractions can be compared by comparing the X volume% distillation temperatures of the multiple fractions. X is greater than 0 and less than or equal to 100. The X volume% distillation temperature is the temperature at which X volume% is distilled out relative to the total volume of the fraction. Examples of X include 10, 50, and 90. When the chemical product refined by the distillation method of this embodiment is a petroleum product (including petroleum base material), the 10% volume distillation temperature, 50% volume distillation temperature, and 90% volume distillation temperature can be determined in accordance with JIS K2254 (2018) "Petroleum products - Method for determining distillation properties".

[0020] Dilution D p and fraction D q The difference in 10% volume distillation temperature is preferably 96 to 144°C, more preferably 103 to 137°C, and even more preferably 110 to 130°C. Dilution D p and fraction D q The difference in 50% volume distillation temperature is preferably 52-83°C, more preferably 57-78°C, and even more preferably 62-73°C. D p and fraction D q The difference in 90% volume distillation temperature is preferably 47-78°C, more preferably 50-75°C, and even more preferably 53-71°C.

[0021] Dilution D q When the flow rate [kL / h] is set to 100%, the fraction D p The proportion of the flow rate [kL / h] is preferably 2-15%, more preferably 2-12%, and even more preferably 2-10%. If the proportion is above the lower limit of the range, D p The flow rate is easy to control. When the ratio is below the upper limit of the range, the distillation efficiency improves.

[0022] Dilution D p When the flow rate [kL / h] is set to 100%, the fraction D q The fraction D to be mixed inp The proportion of the flow rate [kL / h] is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. When the proportion is above the lower limit, the temperature near the top of the distillation column is less likely to fall below the dew point, and the generation of condensed water at the top of the distillation column can be suppressed. Distillation D p When the flow rate [kL / h] is set to 100%, the fraction D q The fraction D to be mixed in p The percentage of the flow rate [kL / h] should be less than 100%.

[0023] The aforementioned fraction D q When the flow rate [kL / h] is set to 100%, the fraction D q The fraction D to be mixed in p The proportion of the flow rate [kL / h] is preferably 1 to 15%, more preferably 1 to 12%, and even more preferably 2 to 10%. If the proportion is greater than or equal to the lower limit of the range, the supply port S q The fraction D supplied to p The flow rate is easy to control. When the ratio is below the upper limit of the range, the distillation efficiency improves.

[0024] D1~D n When the total flow rate [kL / h] is set to 100%, D p The proportion of the flow rate [kL / h] is preferably 2-13%, more preferably 2-11%, and even more preferably 2-9%. If the proportion is above the lower limit of the range, D p The flow rate is easy to control. When the ratio is below the upper limit of the range, the distillation efficiency improves.

[0025] D1~D n When the total flow rate [kL / h] is set to 100%, the supply port S p The fraction D supplied to pThe proportion of the flow rate [kL / h] is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less. When the proportion is below the upper limit, the temperature near the top of the distillation column is less likely to fall below the dew point, and the generation of condensate at the top of the distillation column can be suppressed. D1~D n When the total flow rate [kL / h] is set to 100%, the supply port S p The fraction D supplied to p The percentage of the flow rate [kL / h] should be greater than 0%.

[0026] D1~D n When the total flow rate [kL / h] is set to 100%, the supply port S q The fraction D supplied to p The percentage of the flow rate [kL / h] is preferably 1 to 13%, more preferably 1 to 11%, and even more preferably 1 to 9%. If the percentage is above the lower limit of the range, the supply port S q The fraction D supplied to p The flow rate is easy to control. When the ratio is below the upper limit of the range, the distillation efficiency improves.

[0027] D1~D n When the total flow rate [kL / h] is set to 100%, fraction D q The proportion of the flow rate [kL / h] is preferably 87% to 99%, more preferably 89% to 98%, and even more preferably 91% to 98%. If the proportion is above the lower limit of the range, the distillation efficiency improves. If it is below the upper limit of the range, D p It is easy to control the flow rate.

[0028] D1~D n When the total flow rate [kL / h] is set to 100%, fraction D p and fraction D q The proportion of the total flow rate [kL / h] is preferably 80-100%, more preferably 90-100%, and even more preferably 95-100%.

[0029] n is preferably between 2 and 7, more preferably between 2 and 4, and even more preferably 2. p It is preferable that it is D1.

[0030] In this embodiment, supply ports S1~S n Preferably, these elements are positioned sequentially from the top to the bottom of the distillation column. The distillation equipment and operating method suitably used in the distillation method of this embodiment will be described below with reference to Figure 1.

[0031] (Distillation equipment) Figure 1 is a schematic diagram showing an example of a distillation apparatus for carrying out the distillation method of this embodiment. Figure 1 shows fractions D1 to D n , supply port S1~S n In this case, n=5, D p =D2, D q This is a distillation apparatus for carrying out the distillation method of this embodiment when =D3.

[0032] The distillation apparatus includes a distillation column 1. A distillation column known in this art can be used as the distillation column 1. Examples include a tray column, which is a type of distillation column divided by several horizontal trays, and a packed column, which is a distillation column with packing material installed inside. The type and size of the distillation column can be selected according to its purpose.

[0033] The distillation column 1 has feed ports S111, S212, S313, S414, and S515 located in order from the top to the bottom of the column. As shown in Figure 1, it is preferable that the feed ports S1 to S5 are located in order from the top to the bottom of the distillation column 1.

[0034] Pipes L11, L12, L13, L14, and L15 are connected to the feed ports S111, S212, S313, S414, and S515 of the distillation column 1, respectively. If the distillation column 1 is a tray column, it is preferable that pipes L11, L12, L13, L14, and L15 are connected to trays inside the distillation column via the feed ports S111, S212, S313, S414, and S515 of the distillation column 1, respectively. Pipe L17 is connected to the top of the distillation column 1. Pipe L18 is connected to the bottom of the distillation column 1. Pipe L16 is connected to pipes L12 and L13. A control valve V1 is installed downstream of the junction of pipe L12 with pipe L16. A control valve V2 is installed in pipe L16.

[0035] (Driving method) Distillate D1 is supplied to distillation column 1 from supply port S111 via piping L11. Distillate D3 is supplied to distillation column 1 from supply port S313 via piping L13. Distillate D4 is supplied to distillation column 1 from supply port S414 via piping L14. Distillate D5 is supplied to distillation column 1 from supply port S515 via piping L15. With control valves V1 and V2 open, a portion of fraction D2 is supplied to distillation column 1 from supply port S313 through piping L12, L16, and L13. The remaining fraction D2 is supplied to distillation column 1 from supply port S212 through piping L12.

[0036] The ratio of the flow rate of fraction D2 supplied to supply port S212 to the flow rate of fraction D2 supplied to supply port S313 can be adjusted by controlling the opening of control valves V1 and V2. In Figure 1, control valves V1 and V2 control the ratio of the flow rate of fraction D2 supplied to supply port S212 to the flow rate of fraction D2 supplied to supply port S213, but the system is not limited to control valves, and similar devices such as mass flow controllers can also be used.

[0037] The inside of the distillation column 1 is heated as needed, and distillation is performed. The light fraction is obtained from the piping L17 connected to the top of the distillation column 1, and the heavy fraction is obtained from the piping L18 connected to the bottom of the distillation column 1. The chemical product purified by the distillation method of this embodiment (i.e., the chemical product produced) may be either the light fraction or the heavy fraction, but the heavy fraction is preferred. The heating of the distillation column 1 can be carried out by methods known in the art. For example, fractions D1 to D n The solution may be preheated before being supplied to the distillation column 1, or it may be heated in a heat exchanger or the like. In this embodiment, it is preferable to supply steam to lower the partial pressure of the fraction in the distillation column.

[0038] <Chemicals> The chemicals purified by the distillation method of this embodiment are not particularly limited, as long as they are purified by supplying two or more fractions with different boiling point ranges to a distillation column and distilling them, and are purified by a distillation method that makes operation difficult due to the generation of condensate near the top of the distillation column. In other words, chemicals purified by a distillation method in which water is present in the distillation column and problems such as corrosion may occur due to the generation of condensate are preferred. Among these, petroleum products are preferred, and petroleum-based materials are more preferred. When purifying petroleum products such as petroleum-based materials, chlorine compounds derived from crude oil may be present in the distillation column, and it is known that when condensate is generated, it becomes highly corrosive hydrochloric acid, which corrodes the distillation column (trays, etc.). In this specification, “petroleum products” include both products offered to consumers and petroleum base materials that precede such products. Specifically, it means crude oil-derived products such as liquefied petroleum gas, gasoline, naphtha, kerosene, jet fuel oil, diesel fuel, lubricating oil base oil, heavy oil, and asphalt, which are manufactured in petroleum refining facilities, as well as petrochemical products such as aromatic compounds and olefins. The crude oil-derived products include both products offered to consumers and petroleum base materials that precede such products. Hereinafter, products offered to consumers will be referred to with the prefix “product,” while petroleum base materials will be referred to by name only. For example, a diesel fuel product offered to consumers will be referred to as “product diesel fuel,” and its precursor petroleum base material, diesel fuel base material, will be referred to as “diesel fuel.” The petroleum product is preferably a petroleum-based material, and more preferably diesel fuel or kerosene.

[0039] (Method of manufacturing light oil or kerosene) A method for producing light oil or kerosene using the distillation method of this embodiment will be described. In the case of the method for producing light oil or kerosene, fractions D1 to D will be used as described below. n , supply port S1~S n In this case, n=2, D p =D1, D q =D2.

[0040] (Light oil or kerosene manufacturing facilities) Figure 2 is a schematic diagram showing an example of manufacturing equipment for carrying out a method of manufacturing light oil or kerosene. The manufacturing facility comprises a kerosene desulfurization unit 2, a separator 3, a gas separator 4, and a distillation column (tray column) 5. The tray column 5 has supply ports S151 and S252 located sequentially from the top to the bottom of the column. Separator 3 is a distillation column that does not have horizontal shelves (trays) inside the column.

[0041] The upper part (inlet) of the kerosene desulfurization unit 2 is connected to the atmospheric distillation unit (not shown) via piping L21. The lower part (outlet) of the kerosene desulfurization unit and the middle section of separator 3 are connected via piping L31. The top of separator 3 and gas separator 4 are connected via piping L41. Piping L42 is connected to the top of the gas separator. The bottom of separator 3 and the supply port S252 of tray column 5 are connected via piping L52. Gas separator 4 and the supply port S151 of tray column 5 are connected via piping L51. Multiple trays 54 are installed inside tray column 5. Piping L51 and piping L52 are connected to the trays 54 inside tray column 5 via supply ports S151 and S252, respectively. Piping L55 is connected to the top of tray column 5. Piping L56 is connected to the bottom of tray column 5. A pipe L54 is connected between the bottom of the shelf tower 5 and the lowest tray 54. In Figure 2, the pipe L54 is connected between the bottom of the shelf tower 5 and the lowest tray 54, but the connection position of the pipe L54 can be changed as appropriate. Pipe L53 is connected to pipes L51 and L52. A control valve V3 is installed downstream of the junction of pipe L51 with pipe L53. A control valve V4 is installed in pipe L53.

[0042] (Driving method) The following describes the operating procedure for the production of diesel fuel, but the same procedure can be applied to kerosene. Straight-run diesel fuel obtained by atmospheric distillation of crude oil in an atmospheric distillation unit, cracked diesel fuel obtained from an indirect desulfurization unit or a direct desulfurization unit, or catalytically reformed diesel fuel obtained from a fluid catalytic cracking unit (hereinafter, these are collectively referred to as "desulfurized straight-run diesel fuel, etc.") is supplied to the kerosene desulfurization unit 2 through piping L21. Although not shown in the diagram, piping L21 may also be connected to piping to which cracked diesel fuel obtained from an indirect desulfurization unit or a direct desulfurization unit, or catalytically reformed diesel fuel obtained from a fluid catalytic cracking unit, is supplied. Desulfurized straight-run diesel fuel, etc. obtained by desulfurization treatment in the kerosene desulfurization unit 2 is supplied to the separator 3 through piping L31. Heavy fraction 1 obtained from the bottom of the separator 3 is supplied to the tray column 5 from the supply port S252 through piping L52. Light fraction 1 obtained from the top of the separator 3 is supplied to the gas separator 4 through piping L41. Gas is removed from the piping L42 of the gas separator 4 to obtain the light fraction 1'. By opening control valves V3 and V4, a portion of the light fraction 1' is supplied to the tray column 5 from supply port S252 through piping L51, L53, and L52. The remaining light fraction 1' is supplied to the tray column 5 from supply port S151 through piping L51. The ratio of the flow rate of the light fraction 1' supplied to supply port S151 to the flow rate of the light fraction 1' supplied to supply port S252 can be adjusted by controlling the opening of control valves V3 and V4, etc.

[0043] The light fraction 1' in piping L51 and L53 upstream of control valves V3 and V4 is a liquid, and by passing through control valve V3 or V4, it becomes a mixture of liquid and gas. The pressure is higher upstream of control valve V3 than downstream. Similarly, the pressure is higher upstream of control valve V4 than downstream. The heavy fraction 1 obtained from the bottom of separator 3 in pipe L52 is a liquid, and after passing through a control valve (not shown) installed in pipe L52, it becomes a mixture of liquid and gas. The pressure is higher upstream of the control valve (not shown) than downstream. The control valve (not shown) is installed upstream of control valve V4 in pipe L52.

[0044] Steam is supplied into the tray column 5 from piping L54 to perform distillation. Naphtha fraction, gas, etc. are discharged from piping L55 connected to the top of the tray column 5, and diesel fuel is obtained from piping L56 connected to the bottom of the tray column 5.

[0045] In the case of a method for producing light oil or kerosene, the steam supply rate is preferably 1.0 to 7.0 [Ton / h], more preferably 1.5 to 6.5 [Ton / h], and even more preferably 2.0 to 6.0 [Ton / h].

[0046] In the case of a method for producing light oil or kerosene, the flow rate of the light fraction 1' supplied to the supply port S151 is preferably 17 [KL / h] or less, more preferably 13 [KL / h] or less, and even more preferably 10 [KL / h] or less.

[0047] In the case of a method for producing light oil or kerosene, the flow rate of the light fraction 1' supplied to the supply port S252 is preferably 2 to 43 [KL / h], more preferably 2 to 36 [KL / h], and even more preferably 3 to 30 [KL / h].

[0048] In the case of a method for producing light oil or kerosene, the flow rate of the heavy fraction 1 supplied to the supply port S252 is preferably 130 to 324 [KL / h], more preferably 134 to 320 [KL / h], and even more preferably 137 to 317 [KL / h].

[0049] In the case of a method for producing diesel fuel, the 10% by volume distillation temperature of the light fraction 1' is preferably 120 to 150°C, more preferably 125 to 145°C, and even more preferably 130 to 140°C. The 50% by volume distillation temperature is preferably 216 to 233°C, more preferably 219 to 230°C, and even more preferably 222 to 227°C. The 90% by volume distillation temperature is preferably 277 to 289°C, more preferably 279 to 287°C, and even more preferably 281 to 285°C.

[0050] In the case of a method for producing diesel fuel, the 10% by volume distillation temperature of heavy fraction 1 is preferably 246 to 264°C, more preferably 248 to 262°C, and even more preferably 250 to 260°C. The 50% by volume distillation temperature is preferably 285 to 299°C, more preferably 287 to 297°C, and even more preferably 289 to 295°C. The 90% by volume distillation temperature is preferably 336 to 355°C, more preferably 337 to 354°C, and even more preferably 338 to 352°C.

[0051] In the case of a method for manufacturing light oil or kerosene, the supply port S151 is preferably connected to a tray located at the 3-43% position from the top of the tower, more preferably to a tray located at the 5-40% position, and even more preferably to a tray located at the 7-30% position, when the total number of trays in the tray tower is considered to be 100%.

[0052] In the case of a method for manufacturing light oil or kerosene, the supply port S252 is preferably connected to a tray at a position 43-57% from the top of the tower, more preferably to a tray at a position 44-56%, and even more preferably to a tray at a position 45-55%, when the total number of trays in the tray tower is considered to be 100%.

[0053] The diesel fuel produced by the diesel fuel production method of this embodiment preferably has the following properties.

[0054] The flash point of diesel fuel is preferably 45 to 110°C, more preferably 50 to 110°C, and even more preferably 70 to 110°C. The flash point of diesel fuel can be determined in accordance with "JIS K2265:2007".

[0055] The 10% volume distillation temperature of diesel fuel is preferably 170-260°C, more preferably 180-260°C, and even more preferably 220-260°C. The 50% volume distillation temperature is preferably 260-320°C, more preferably 270-320°C, and even more preferably 280-310°C. The 90% volume distillation temperature is preferably 295-360°C, more preferably 310-360°C, and even more preferably 325-360°C.

[0056] The sulfur content of the diesel fuel is preferably 10 ppm by mass or less.

[0057] The density of diesel fuel at 15°C is preferably 0.800 to 0.860 g / mL, more preferably 0.805 to 0.860 g / mL, and even more preferably 0.810 to 0.860 g / mL.

[0058] The kerosene produced by the kerosene production method of this embodiment preferably has the following properties.

[0059] The flash point of kerosene is preferably 40-60°C, and more preferably 41-60°C. The flash point of kerosene can be determined in accordance with "JIS K2265:2007".

[0060] The initial boiling point of kerosene is preferably 135-170°C, and more preferably 140-170°C. The 50% volume distillation temperature is preferably 165-220°C, and more preferably 190-220°C. The 95% volume distillation temperature is preferably 215-270°C, and more preferably 220-270°C.

[0061] The sulfur content of kerosene is preferably 80 ppm by mass or less, and more preferably 10 ppm by mass or less.

[0062] The density of kerosene at 15°C is preferably 0.780 to 0.810 g / mL, and more preferably 0.790 to 0.810 g / mL.

[0063] The diesel fuel and kerosene produced by the above manufacturing method may be used as is as the finished diesel fuel and kerosene, or they may be made into finished diesel fuel and kerosene by blending them with other base materials and various additives. [Examples]

[0064] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The reference numerals in the examples refer to the reference numerals in Figure 2.

[0065] <Measurement method> The dew point near the top of the distillation column was determined using Antoine's formula, based on the amount of steam introduced into the column, the naphtha fraction extracted from the top of the column, the temperature near the top of the column, the pressure near the top of the column, and the amount of reflux at the top. The flash point of diesel fuel was determined in accordance with "JIS K2265:2007".

[0066] [Example 1] Straight-run diesel fuel, obtained by atmospheric distillation of crude oil in an atmospheric distillation unit, was supplied to the kerosene desulfurization unit 2 via piping L21. The desulfurized straight-run diesel fuel, obtained by desulfurization treatment in the kerosene desulfurization unit 2, was supplied to separator 3 via piping L31. Heavy fraction 1, obtained from the bottom of separator 3, was supplied to tray column 5 via piping L52 and supply port S252. Light fraction 1, obtained from the top of separator 3, was supplied to gas separator 4 via piping L41. Gas was removed from piping L42 of gas separator 4 to obtain light fraction 1'. With control valves V3 and V4 open, a portion of light fraction 1' was supplied to tray column 5 via piping L51, L53, and L52 and supply port S252. The remainder of light fraction 1' was supplied to tray column 5 via piping L51 and supply port S151. The ratio of the flow rate of light fraction 1' supplied to supply port S151 to the flow rate of light fraction 1' supplied to supply port S252 was adjusted by controlling the opening degrees of control valves V3 and V4. Steam was supplied to the tray column 5 from piping L54 for distillation. Naphtha fraction, gas, etc., were discharged from piping L55 connected to the top of the tray column 5, and diesel fuel was obtained from piping L56 connected to the bottom of the tray column 5. Table 1 shows the flow rates of light fraction 1' supplied to supply port S151, the flow rate of light fraction 1' supplied to supply port S252, and the flow rate of heavy fraction 1 supplied to supply port S252. Table 1 also shows the flash point of the diesel fuel obtained from the bottom of the tray tower 5, the dew point temperature near the top of the tray tower 5, the temperature near the top of the tray tower 5, and the steam supply rate.

[0067] [Comparative Example 1] With the control valve V3 closed, all of the light fraction 1' was supplied to the tray tower 5 from the supply port S252 through piping L51, L53, and L52, and diesel fuel was produced in the same manner as in Example 1, except that the steam supply amount was changed. Table 1 shows the flow rate of light fraction 1' supplied to supply port S252 and the flow rate of heavy fraction 1 supplied to supply port S252. Table 1 also shows the flash point of the diesel fuel obtained from the bottom of the tray tower 5, the dew point temperature near the top of the tray tower 5, the temperature near the top of the tray tower 5, and the steam supply amount.

[0068] [Comparative Example 2] With the control valve V4 closed, all of the light fraction 1' was supplied to the tray tower 5 from the supply port S151 through the piping L51, and the amount of steam supplied was changed. Diesel fuel was produced in the same manner as in Example 1. Table 1 shows the flow rate of light fraction 1' supplied to supply port S151 and the flow rate of heavy fraction 1 supplied to supply port S252. Table 1 also shows the flash point of the diesel fuel obtained from the bottom of the tray tower 5, the dew point temperature near the top of the tray tower 5, the temperature near the top of the tray tower 5, and the steam supply rate.

[0069] [Table 1]

[0070] In Example 1, it was possible to reduce the amount of steam supplied and to operate stably with the temperature near the top of the tower exceeding the dew point temperature. In Comparative Example 1, it was possible to operate with the temperature near the top of the tower exceeding the dew point temperature, but it required a much larger amount of steam than Example 1. In Comparative Example 2, it was possible to reduce the amount of steam supplied compared to Comparative Example 1, but the temperature near the top of the tower became the dew point temperature, making long-term operation difficult.

[0071] In the present invention, the light fraction 1' and the heavy fraction 1 are supplied from separate feed ports. By supplying the light fraction 1' from the feed port on the top side of the column, it is considered that the light fraction 1' is not substantially contained on the bottom side of the column, thus enabling efficient distillation. Furthermore, in the present invention, by mixing a portion of the light fraction 1' with the heavy fraction 1 to obtain a mixed fraction, and supplying this mixture from the feed port on the bottom side of the column, it is considered that steam is carried along with the light fraction 1' as it evaporates toward the top of the column, thereby suppressing the temperature drop near the top of the column. [Industrial applicability]

[0072] The distillation method according to the present invention is useful because it reduces the required energy and enables stable operation in a distillation method that purifies a chemical product by supplying two or more fractions with different boiling point ranges to a distillation column and distilling them. [Explanation of symbols]

[0073] 1…Distillation column, 2…Kerosene desulfurization unit, 3…Separator, 4…Gas separator, 5…Distillation column (tray column), 11…Feed port S1, 12…Feed port S2, 13…Feed port S3, 14…Feed port S4, 15…Feed port S5, 51…Feed port S1, 52…Feed port S2, 54…Tray, L11, L12, L13, L14, L15, L16, L17, L18, L21, L31, L41, L42, L51, L52, L53, L54, L55, L56…Piping, V1, V2, V3, V4…Control valve

Claims

1. Two or more fractions D with different boiling point ranges １ ~D ｎ (n is an integer greater than or equal to 2, indicating the type of fraction; a smaller n indicates a fraction with a lower boiling point range) These represent different feed ports S of the distillation column. １ ~S ｎ (n is the same as above, and the fraction D １ ~D ｎ A distillation method for purifying a chemical by supplying it to a corresponding supply port (indicating the supply port) and distilling it, the fraction D １ ~D ｎ One of the fractions D ｐ A part of which is mixed with another fraction D ｑ to obtain a mixed fraction, which is supplied to the supply port S ｑ A distillation method.

2. The aforementioned supply port S １ ~S ｎ The distillation method according to claim 1, wherein the elements are located sequentially from the top to the bottom of the distillation column.

3. The aforementioned fraction D ｐ The boiling point range of the other fraction D ｑ A distillation method according to claim 1 or 2, wherein the boiling point range is lower than that of the boiling point range

4. The aforementioned fraction D ｑ When the flow rate [kL / h] is set to 100%, the fraction D ｐ The distillation method according to claim 1 or 2, wherein the proportion of the flow rate [kL / h] is 2 to 15%.

5. The aforementioned fraction D ｐ When the flow rate [kL / h] is set to 100%, the fraction D ｑ The fraction D to be mixed with ｐ The distillation method according to claim 1 or 2, wherein the proportion of the flow rate [kL / h] is 40% or more.

6. The aforementioned fraction D ｑ When the flow rate [kL / h] is set to 100%, the fraction D ｑ The fraction D to be mixed with ｐ The distillation method according to claim 1 or 2, wherein the proportion of the flow rate [kL / h] is 1 to 15%.

7. The aforementioned fraction D １ ~D ｎ When the total flow rate [kL / h] is set to 100%, the supply port S ｐ The fraction D supplied to ｐ The distillation method according to claim 1 or 2, wherein the proportion of the flow rate [kL / h] is 5% or less.

8. The aforementioned fraction D ｐ This is fraction D １ The distillation method according to claim 1 or 2.

9. The distillation method according to claim 1 or 2, wherein n is 2 or more and 7 or less.

10. The distillation method according to claim 9, wherein n is 2.

11. The distillation method according to claim 1 or 2, wherein the chemical is a petroleum-based material.

12. The distillation method according to claim 11, wherein the petroleum base material is light oil or kerosene.

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