Liquid-phase hydroisomerization system and process therefor and use thereof

Abstract

Provided are a liquid-phase hydroisomerization system and a process therefor and use thereof. The system comprises a gas-liquid mixer (3), a hydroisomerization reactor (4) and a fractionating column (6). An oil product and hydrogen are mixed as a liquid hydrogen-oil mixture, and are introduced into the hydroisomerization reactor for a hydroisomerization reaction, and after being fractionated, a target product is led out. A supplemental hydrogen-dissolving inner member is provided at least between a group of two adjacent catalyst bed layers in order to supplement hydrogen to the reactants. The process cancels a circulating hydrogen compressor, has a simple process flow, and can be applied to the production of a lubricant base oil by the hydroisomerization of a lubricant raw material or the production of a low freezing point diesel by the hydroisomerization of and the reduction in the freezing point of a diesel raw material.

Claims

1. A liquid-phase hydroisomerization system, comprising: a hydrogen-dissolving unit, a hydroisomerization reactor, and a fractionating column; wherein the hydrogen-dissolving unit comprises an oil feed line, a hydrogen feed line and a hydrogen-oil-mixture line, the hydrogen-oil-mixture line is in communication with the bottom of the hydroisomerization reactor, and the top of the hydroisomerization reactor is in communication with the fractionating column; the hydroisomerization reactor includes at least two catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between at least one pair of two adjacent catalyst beds; the internal dissolved-hydrogen replenishment member comprises a bottom sieve separating plate, a middle mixing space and a top separating plate, the top separating plate is provided with multiple liquid discharging pipes, and the middle mixing space is provided with a hydrogen inlet and a hydrogen outlet; hydrogen and oil are mixed in the middle mixing space, the liquid phase in which the hydrogen is dissolved is discharged through the liquid discharging pipes, and undissolved hydrogen gas is discharged through the hydrogen outlet.

2. The liquid-phase hydroisomerization system according to claim 1, wherein the fractionating column comprises at least one cut fraction line in communication with the oil feed line.

3. The liquid-phase hydroisomerization system according to claim 1, wherein in the hydroisomerization reactor, there are 2 to 5 catalyst beds.

4. The liquid-phase hydroisomerization system according to claim 1, wherein the system further comprises a hydrofining reactor, provided before or after the hydroisomerization reactor; if the hydrofining reactor is provided before the hydroisomerization reactor, the hydrogen-oil-mixture line is in communication with the bottom of the hydrofining reactor, the top of the hydrofining reactor is in communication with the bottom of the hydroisomerization reactor, and the top of the hydroisomerization reactor is in communication with the fractionating column; if the hydrofining reactor is provided after the hydroisomerization reactor, the hydrogen-oil-mixture line is in communication with the bottom of the hydroisomerization reactor, the top of the hydroisomerization reactor is in communication with the bottom of the hydrofining reactor, the top of the hydrofining reactor is in communication with the fractionating column.

5. The liquid-phase hydroisomerization system according to claim 4, wherein the hydrofining reactor comprises at least two catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between two adjacent catalyst beds.

6. The liquid-phase hydroisomerization system according to claim 5, wherein in the hydrofining reactor, there are 2 to 5 catalyst beds.

7. A liquid-phase hydroisomerization process using the system according to claim 1, wherein the process comprises: 1) mixing oil and hydrogen in a hydrogen-dissolving unit to obtain a liquid mixture of hydrogen and oil; 2) feeding the mixture of hydrogen and oil to a subsequent hydroisomerization reactor and/or a hydrofining reactor to allow for a hydroisomerization reaction and/or a hydrofining reaction; and 3) feeding the resultant obtained in 2) to a fractionating column for fractionation, and obtaining a fractionated target product.

8. The process according to claim 7, wherein the oil is an oil fraction having a distillation range of 65 C. to 550 C.

9. The process according to claim 8, wherein the oil fraction includes one of, or a combination of more of, a hydrocracking tail oil, a catalytic diesel oil, a coking diesel oil, a straight-run diesel oil, a straight-run wax oil, a low-pressure oil fraction, a coking wax oil, a deasphalted oil and a synthetic oil.

10. The process according to claim 9, wherein the oil fraction is a hydrocracking tail oil.

11. The process according to claim 7, wherein the hydrogen dissolved in the mixture of hydrogen and oil is in a saturated state or a supersaturated state.

12. The process according to claim 7, wherein the conditions of the hydroisomerization reaction are: a reaction pressure of 6.0 MPa to 16.0 MPa, a reaction temperature of 320 C. to 395 C., and a volume space velocity of 0.2 h.sup.1 to 2.0 h.sup.1; and the conditions of the hydrofining reaction are: a reaction pressure of 6.0 MPa to 16.0 MPa, a reaction temperature of 220 C. to 385 C., and a volume space velocity of 0.2 h.sup.1 to 3.0 h.sup.1.

13. The process according to claim 7, wherein the process further comprises introducing one or more fractions obtained after the fractionation other than the target product into the oil.

14. The liquid-phase hydroisomerization system according to claim 2, wherein the system further comprises a hydrofining reactor, provided before or after the hydroisomerization reactor; if the hydrofining reactor is provided before the hydroisomerization reactor, the hydrogen-oil-mixture line is in communication with the bottom of the hydrofining reactor, the top of the hydrofining reactor is in communication with the bottom of the hydroisomerization reactor, and the top of the hydroisomerization reactor is in communication with the fractionating column; if the hydrofining reactor is provided after the hydroisomerization reactor, the hydrogen-oil-mixture line is in communication with the bottom of the hydroisomerization reactor, the top of the hydroisomerization reactor is in communication with the bottom of the hydrofining reactor, the top of the hydrofining reactor is in communication with the fractionating column.

15. The liquid-phase hydroisomerization system according to claim 3, wherein the system further comprises a hydrofining reactor, provided before or after the hydroisomerization reactor; if the hydrofining reactor is provided before the hydroisomerization reactor, the hydrogen-oil-mixture line is in communication with the bottom of the hydrofining reactor, the top of the hydrofining reactor is in communication with the bottom of the hydroisomerization reactor, and the top of the hydroisomerization reactor is in communication with the fractionating column; if the hydrofining reactor is provided after the hydroisomerization reactor, the hydrogen-oil-mixture line is in communication with the bottom of the hydroisomerization reactor, the top of the hydroisomerization reactor is in communication with the bottom of the hydrofining reactor, the top of the hydrofining reactor is in communication with the fractionating column.

16. The liquid-phase hydroisomerization system according to claim 14, wherein the hydrofining reactor comprises at least two catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between two adjacent catalyst beds.

17. The liquid-phase hydroisomerization system according to claim 16, wherein in the hydrofining reactor, there are 2 to 5 catalyst beds.

18. The liquid-phase hydroisomerization system according to claim 15, wherein the hydrofining reactor comprises at least two catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between two adjacent catalyst beds.

19. The liquid-phase hydroisomerization system according to claim 18, wherein in the hydrofining reactor, there are 2 to 5 catalyst beds.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic view of the structure of the internal dissolved-hydrogen replenishment member in Example 1; and

(2) FIG. 2 is a schematic view of the liquid-phase hydroisomerization process in Example 1;

REFERENCE NUMBERS

(3) 1 Hydrogen line; 2 Oil feed line; 3 Gas-liquid mixer; 4 Hydroisomerization reactor; 5. Hydrofining reactor; 6 Fractionating column; 7 Product line; 8 Circulating pump.

DETAILED DESCRIPTION OF INVENTION

(4) The technical solutions of the present invention will now be described in detail in order to provide a better understanding of the technical features, objectives and advantages of the present invention, but the following description is not to be construed as limiting the scope of the invention.

(5) The raw materials used in Examples 1-3 are shown in Table 1:

(6) TABLE-US-00001 TABLE 1 Properties of the feedstock oils A, B and C Feedstock Feedstock Feedstock Item oil A oil B oil C Feedstock oil 200SN 650SN hydrocracking pre-refined pre-refined tail oil oil oil Density (20 C.), 0.8646 0.8580 0.8367 g/cm.sup.3 Viscosity at 100 C., 5.204 8.73 4.34 mm.sup.2/S Viscosity at 40 C., 27.92 18.9 mm.sup.2/S Viscosity index 118 140 142.7 Solidification point 2.2 58 30.7 ( C.) Total sulfur, g/g <6 <6 <6 Total nitrogen, g/g <2 <2 <2 Distil- HK/10% 340/393 412/468 323/389 lation 30%/50% 412/426 491/503 411/427 range 70%/90% 440/458 515/532 448/484 ( C.) 95%/KK 464/476 540/556 501/515

Example 1

(7) This Example provides a liquid-phase hydroisomerization system, which comprises (wherein the first reactor is a hydroisomerization reactor, and the second reactor is a hydrofining reactor):

(8) a gas-liquid mixer 3, a hydroisomerization reactor 4, a hydrofining reactor 5 and a fractionating column 6; wherein

(9) the hydroisomerization reactor 4 is provided with three catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between each pair of adjacent catalyst beds, with each catalyst bed filled with a hydroisomerization de-waxing catalyst;

(10) the internal dissolved-hydrogen replenishment member (the structure thereof is shown in FIG. 1) comprises a bottom sieve separating plate, a middle mixing space and a top separating plate, the top separating plate is provided with multiple liquid discharging pipes, and the middle mixing space is provided with a hydrogen inlet and a hydrogen outlet; hydrogen and oil are mixed in the middle mixing space, the liquid phase in which hydrogen is dissolved is discharged through the liquid discharging pipes, and undissolved hydrogen is discharged through the hydrogen outlet;

(11) the hydrofining reactor 5 is provided with three catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between each pair of adjacent catalyst beds, with each catalyst bed filled with a hydrofining catalyst;

(12) the hydrogen line 1 is divided into three branches, namely the first branch of hydrogen, the second branch of hydrogen, and the third branch of hydrogen, wherein the first branch of hydrogen is in communication with the oil feed line 2, the second branch of hydrogen is divided into two parts which are in communication with the two internal dissolved-hydrogen replenishment members in the hydroisomerization reactor 4, respectively, and the third branch of hydrogen is divided into two parts which are in communication with the two internal dissolved-hydrogen replenishment members in the hydrofining reactor 5, respectively;

(13) the oil feed line 2 is in communication with the gas-liquid mixer 3, the gas-liquid mixer 3 is in communication with the feed inlet at the bottom of the hydroisomerization reactor 4 through a hydrogen-oil-mixture line, the feed outlet on top of the hydroisomerization reactor 4 is in communication with the feed inlet at the bottom of the hydrofining reactor 5, the feed outlet on top of the hydrofining reactor 5 is in communication with the rectification column 6, and the rectification column 6 is provided with a product line 7 and a non-product fraction line, wherein the product line 7 is directed out of the boundary zone, the non-product fraction line is in communication with the inlet of the circulating pump 8, and the outlet of the circulating pump 8 is in communication with the oil feed line 2.

(14) The liquid-phase hydroisomerization process:

(15) a liquid-phase hydroisomerization process using the process system described above (the schematic view of the process is shown in FIG. 2), which comprises the following steps:

(16) 1) mixing the feedstock A and hydrogen in the gas-liquid mixer 3 to form a mixture of hydrogen and oil in a pure liquid state, and feeding the mixture of hydrogen and oil to the hydroisomerization reactor 4 from the bottom;

(17) 2) in the hydroisomerization reactor 4, allowing the mixture of hydrogen and oil to undergo a hydroisomerization reaction to obtain a hydroisomerization reaction product, wherein the processing conditions of the hydroisomerization were: a hydrogen partial pressure of 12.2 MPa, a reaction temperature of 320 C., and a volume space velocity of 1.2 h.sup.1; and the isodewaxing catalyst used in the reaction was the noble metal catalyst PIC-812;

(18) 3) feeding the hydroisomerization reaction product to the hydrofining reactor 5 from the bottom for hydrofining, and feeding the product of hydrofining to the fractionating column 6, wherein the processing conditions of the hydrofining were: a hydrogen partial pressure of 12.2 MPa, a reaction temperature of 220 C., and a volume space velocity of 2.0 h.sup.1;

(19) 4) circulating the 2 cSt (centistoke) or 6 cSt fraction obtained after cutting the mixed product from the fractionating column 6, while reserving the target product as the other fraction (if the 2 cSt fraction is the target product, then the 6 cSt fraction is used as the circulating oil), wherein the properties of the product are shown in Table 2.

(20) TABLE-US-00002 TABLE 2 Properties of the product obtained in this Example Item Example 1 Liquid yield, % 99.8 Total yield of base oil, % (uncirculated) 88.9 Yield of 6 cSt base oil, % (circulated) 81.1 Properties pour point ( C.) 18 of 6 cSt clouding point ( C.) 17 base oil Viscosity at 100 C., mm.sup.2/s 6.163 Viscosity index 108

(21) As can be seen from Table 2, the system provided by this Example gave a yield of base oil of 88.9%, and can produce 6 cSt base oil at a maximum yield.

Example 2

(22) This Example provides a liquid-phase hydroisomerization process, which uses a system similar to that in Example 1, except that the hydroisomerization reactor and the hydrofining reactor are each provided with four catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between each pair of two adjacent catalyst beds. The process includes the following steps:

(23) 1) mixing the feedstock oil B and hydrogen in the gas-liquid mixer 3 to form a mixture of hydrogen and oil in a pure liquid state, and feeding the mixture of hydrogen and oil to the hydroisomerization reactor 4 from the bottom;

(24) 2) in the hydroisomerization reactor 4, allowing the mixture of hydrogen and oil to undergo a hydroisomerization reaction to obtain a hydroisomerization reaction product, wherein the processing conditions of the hydroisomerization were: a hydrogen partial pressure of 12.2 MPa, a reaction temperature of 365 C., and a volume space velocity of 0.85 h.sup.1; and the isodewaxing catalyst used in the reaction was the noble metal catalyst PIC-812;

(25) 3) feeding the hydroisomerization reaction product to the hydrofining reactor 5 from the bottom for hydrofining, and feeding the product of hydrofining to the fractionating column 6, wherein the processing conditions of the hydrofining were: a hydrogen partial pressure of 12.2 MPa, a reaction temperature of 230 C., and a volume space velocity of 1.42 h.sup.1;

(26) 4) circulating the 2 cSt (centistoke) fraction obtained after cutting the mixed product from the fractionating column 6, while reserving the 10 cSt fraction, wherein the properties of the product are shown in Table 3.

(27) TABLE-US-00003 TABLE 3 Properties of the product obtained in Example 2 Item Example 2 Liquid yield, % 96.7 Total yield of base oil, % (uncirculated) 81.0 Yield of 10 cSt base oil, % (circulated) 73.4 Properties of pour point ( C.) 18 10 cSt clouding point ( C.) 5 base oil Viscosity at 100 C., mm.sup.2/s 10.77 Viscosity index 122

(28) As can be seen from Table 3, the system gave a yield of base oil of 81%, and can produce 10 cSt base oil.

Example 3

(29) This Example provides a liquid-phase hydroisomerization system and process, and the system (comprising the hydroisomerization reactor only) includes:

(30) a gas-liquid mixer 3, a hydroisomerization reactor 4, and a fractionating column 6; wherein

(31) the hydroisomerization reactor 4 is provided with five catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between each pair of adjacent catalyst beds, with each catalyst bed filled with a hydroisomerization de-waxing catalyst;

(32) the internal dissolved-hydrogen replenishment member comprises a bottom sieve separating plate, a middle mixing space and a top separating plate, the top separating plate is provided with multiple liquid discharging pipes, and the middle mixing space is provided with a hydrogen inlet and a hydrogen outlet; hydrogen and oil are mixed in the middle mixing space, the liquid phase in which hydrogen is dissolved is discharged through the liquid discharging pipes, and undissolved hydrogen is discharged through the hydrogen outlet;

(33) the hydrogen line 1 is divided into two branches, namely the first branch of hydrogen and the second branch of hydrogen, wherein the first branch of hydrogen is in communication with the oil feed line 2, and the second branch of hydrogen is divided into four parts which are in communication with the four internal dissolved-hydrogen replenishment members in the hydroisomerization reactor 4, respectively;

(34) the oil feed line 2 is in communication with the gas-liquid mixer 3, the gas-liquid mixer 3 is in communication with the feed inlet at the bottom of the hydroisomerization reactor 4 through the hydrogen-oil-mixture line, the feed outlet on top of the hydroisomerization reactor 4 is in communication with the rectification column 6, and the rectification column 6 is provided with a product line 7 and a non-product fraction line, wherein the product line 7 is directed out of the boundary zone, and the product in the non-product fraction line is not circulated.

(35) The Liquid-Phase Hydroisomerization Process:

(36) a liquid-phase hydroisomerization process using the above system, comprising the following steps:

(37) 1) mixing the feedstock oil C and hydrogen in the gas-liquid mixer 3 to form a mixture of hydrogen and oil in a pure liquid state, and feeding the mixture of hydrogen and oil to the hydroisomerization reactor 4 from the bottom;

(38) 2) in the hydroisomerization reactor 4, allowing the mixture of hydrogen and oil to undergo a hydroisomerization reaction to obtain a hydroisomerization reaction product, wherein the processing conditions of the hydroisomerization were: a hydrogen partial pressure of 15.6 MPa, a reaction temperature of 340 C., and a volume space velocity of 1.5 h.sup.1; and the isodewaxing catalyst used in the reaction was the noble metal catalyst PIC-812;

(39) 3) subjecting the mixed product from the fractionating column 6 to different true-boiling-point cutting processes (three of the process schemes are provided in Table 4) to produce different lubricating oil products, such as 2 cSt (centistoke), 4 cSt (centistoke), 5 cSt (centistoke), 6 cSt (centistoke), and 8 cSt (centistoke), the properties of which are shown in Table 4; wherein all the fractionated products were not circulated.

(40) As can be seen from the data in Table 4, the processing technology provided in the Example gave a yield of base oil from the hydrocracking tail oil of 80% or more, and can produce 2 cSt, 4 cSt II/II+, 5 cSt III, 6 cSt III, and 8 cSt III base oils according to different processing schemes.

(41) TABLE-US-00004 TABLE 4 Properties of the products obtained by different processing schemes of Example 3 Processing Processing Processing Yield, % scheme 1 scheme 2 scheme 3 2 cSt 9.46 9.70 7.08 4 cSt II / 27.34 / 4 cSt II.sup.+ 58.35 / / 5 cSt III / / 83.07 6 cSt III / 53.11 / 8 cSt III 22.34 / / Total yield 100 100 100 Total base oil yield 90.15 90.15 90.15

Example 4

(42) This Example provides a liquid-phase hydroisomerization system and process, and the system comprises (wherein the first reactor is a hydrofining reactor, and the second reactor is a hydroisomerization reactor):

(43) a gas-liquid mixer 3, a hydroisomerization reactor 4, a hydrofining reactor 5, and a fractionating column 6; wherein

(44) the hydroisomerization reactor 4 is provided with three catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between each pair of adjacent catalyst beds, with each catalyst bed filled with a hydroisomerization de-waxing catalyst;

(45) the internal dissolved-hydrogen replenishment member comprises a bottom sieve separating plate, a middle mixing space and a top separating plate, the top separating plate is provided with multiple liquid discharging pipes, and the middle mixing space is provided with a hydrogen inlet and a hydrogen outlet; hydrogen and oil are mixed in the middle mixing space, the liquid phase in which hydrogen is dissolved is discharged through the liquid discharging pipes, and undissolved hydrogen is discharged through the hydrogen outlet;

(46) the hydrofining reactor 5 is provided with three catalyst beds, and an internal dissolved-hydrogen replenishment member is provided between each pair of adjacent catalyst beds, with each catalyst bed filled with a hydrofining catalyst;

(47) the hydrogen line 1 is divided into three branches, namely the first branch of hydrogen, the second branch of hydrogen, and the third branch of hydrogen, wherein the first branch of hydrogen is in communication with the oil feed line 2, the second branch of hydrogen is divided into two parts which are in communication with the two internal dissolved-hydrogen replenishment members in the hydroisomerization reactor 4, respectively, and the third branch of hydrogen is divided into two parts, and in communication with the two internal dissolved-hydrogen replenishment members in the hydrofining reactor 5, respectively;

(48) the oil feed line 2 is in communication with the gas-liquid mixer 3, the gas-liquid mixer 3 is in communication with the feed inlet at the bottom of the hydrofining reactor 5 through a hydrogen-oil-mixture line, the feed outlet on top of the hydrofining reactor 5 is in communication with the feed inlet at the bottom of the hydroisomerization reactor 4, the feed outlet on top of the hydroisomerization reactor 4 is in communication with the rectification column 6, and the rectification column 6 is provided with a product line 7 and a non-product fraction line, wherein the product line 7 is directed out of the boundary zone, the non-product fraction line is in communication with the inlet of the circulating pump 8, and the outlet of the circulating pump 8 is in communication with the oil feed line 2.

(49) The Liquid-Phase Hydroisomerization Process:

(50) a liquid-phase hydroisomerization process using the above system, comprising the following steps:

(51) 1) mixing the feedstock oil D and hydrogen in the gas-liquid mixer 3 to form a mixture of hydrogen and oil in a pure liquid state, and feeding the mixture of hydrogen and oil to the hydrofining reactor 5 from the bottom;

(52) 2) in the hydrofining reactor 5, allowing the mixture of hydrogen and oil to undergo a hydrofining reaction, wherein the processing conditions of the hydrofining were: a pressure of the reaction system of 6.5 MPa, a reaction temperature of 355 C., and a space velocity of 1.5 h.sup.1;

(53) 3) feeding the product of the hydrofining reaction to the hydroisomerization reactor 4 for a hydroisomerization reaction to obtain the product of the hydroisomerization reaction, wherein the processing conditions of the hydroisomerization were: a pressure of the reaction system of 6.5 MPa, a reaction temperature of 350 C., and a space velocity of 1.5 h.sup.1; wherein the catalyst for isomerization and pour point-dropping used in the reaction was a base metal catalyst HIDW, and the product was not circulated. The feedstock oil D and the properties of the product are listed in Table 5.

(54) TABLE-US-00005 TABLE 5 Properties of the feedstock D and the product Properties of oil Feedstock D Product oil Composition, % Straight-run Diesel: Catalytic Diesel = 55:45 Density, g/cm.sup.3 0.8395 0.8265 Distillation range ( C.) 176-355 166-350 Sulfur content, g/g 946 6.4 Nitrogen content, g/g 997 9.6 Cetane number 48.8 50.0 Solidification point ( C.) 4.0 35.7 Diesel yield, % / 89.7

(55) As can be seen from Table 5, the processing technology results in a diesel yield of 89%, lowers the solidification point by 30 C. or more, and can produce a diesel oil with a solidification point as low as 35 C.