Hydrocracking system for increasing yield of aviation kerosene

Abstract

The invention discloses a hydrocracking system for increasing the yield of aviation kerosene. The device comprises a raw oil filter, a raw material tank, a high-pressure feeding pump, a circulating hydrogen heating furnace, a circulating hydrogen compressor, a reactor, a separator, a fractionating tower and a diesel oil circulating pipeline. The method has the advantages that enterprises with the target product of aviation kerosene in some time periods are flexibly solved, a fractionation part product diesel oil circulation process is additionally arranged, all circulation reaction parts of self-produced diesel oil of the system are cracked again, the target product is changed from maximum production of middle distillate oil to high yield of aviation kerosene, the product type is not changed, and the production cost is reduced. And the product yield is adjusted, so that the enterprise can adjust the operation strategy and respond to the market more actively, and the purpose that the enterprise takes the market demand as the guide and serves production and operation is really achieved. The method has the characteristics of small transformation work amount, low investment, flexible diesel cracking until no diesel product and high aviation kerosene yield, and is especially suitable for aviation kerosene yield increasing transformation of oil refining enterprises with low hydrocracking processing load.

Description

Technical Field

[0001] The invention belongs to the technical field of oil refining and chemical engineering, and particularly relates to a hydrocracking system for increasing the production of aviation kerosene. Background Art

[0002] At present, the market of the oil refining and chemical industry has changed from the original supply shortage to the supply and demand relationship of commodity surplus and high-end product scarcity. Therefore, the original product structure of enterprises must be market-oriented, customer-centric, and efficiency-oriented, and timely adjusted to cope with market changes in order to win the initiative of survival and development. At present, among gasoline, jet fuel, and diesel products, the market competition for gasoline and diesel is very fierce. Only the market threshold of jet fuel is high, the demand is stable and growing year by year. Producing more jet fuel according to market conditions is an important manifestation of focusing on business, responding to the market, and occupying the market.

[0003] At present, there are several main solutions for oil refining enterprises to increase the production of aviation kerosene in hydrocracking units:

[0004] 1. Adjust and replace some of the catalysts in the reaction to make them more active and selective, so as to increase the yield of aviation kerosene.

[0005] In response to changes in market demand, some oil refineries usually replace the original intermediate distillate oil catalyst with a flexible catalyst during the shutdown and maintenance of the hydrocracking unit. No process adjustments are made to the raw materials, distillation and other parts. The catalyst cost is high but the operation is simple.

[0006] 2. The single-stage reactor is adjusted to a two-stage process by adding a second precious metal catalyst reactor. The tail oil enters the bed for cracking to increase the yield of aviation kerosene.

[0007] Some oil refineries pursue high jet fuel yields, and adjust the hydrocracking unit from a single-stage hydrocracking process to a two-stage hydrocracking process. The modification and investment are huge, involving the addition of high-pressure reactors, the addition of precious metal catalysts, the addition of high-pressure heat exchangers, the addition of high-pressure second-stage feed pumps, the addition of second-stage heating furnaces, major adjustments to the heat exchange process, adjustments to the cold hydrogen process, etc.

[0008] After the second type of transformation, the reaction continued to occur in the second reactor, the yields of aviation kerosene, naphtha and liquefied gas remained relatively high, and the diesel component still had output. When market conditions changed, the means of adjustment were relatively limited and the benefits could not be optimized.

[0009] Figure 1 The following is a schematic diagram of a hydrocracking system of prior art. Figure 1As shown, the hydrocracking system mainly includes a feedstock oil filter 1, a feedstock tank 2, a high-pressure feed pump 3, a circulating hydrogen heating furnace 4, a circulating hydrogen compressor 5, a reactor 6, a separator 7 and a fractionating tower 8; wherein, a feedstock inlet pipeline 9 from a high-pressure heat exchanger is connected to the middle of the feedstock tank 2; two ends of a feedstock outlet pipeline 10 are respectively connected to the bottom of the feedstock tank 2 and the top of the reactor 6; the inlet and outlet of the feedstock oil filter 1 are connected to the feedstock inlet pipeline 9; the inlet and outlet of the high-pressure feed pump 3 are connected to the feedstock outlet pipeline 10; two ends of a circulating hydrogen pipeline 11 are respectively connected to the top of the reactor 6 and the separator 7; the inlet pipeline of the circulating hydrogen compressor 5 is connected to the bottom of the separator 7; At the top, the outlet pipeline is connected to the circulating hydrogen heating furnace 4, and the outlet pipeline of the circulating hydrogen heating furnace 4 is connected to the top of the reactor 6; one end of the mixing pipeline 12 is connected to the lower end of the reactor 6, and the other end is connected to the tube side inlet of the high-pressure heat exchanger 20; one end of the high-pressure heat exchanger tube side outlet pipeline 21 is connected to the tube side outlet of the high-pressure heat exchanger 20, and the other end is connected to the middle of the separator 7; one end of the separator outlet pipeline 13 is connected to the lower end of the separator 7, and the other end is connected to the lower part of the distillation tower 8; the distillation tower 8 is provided with an upper outlet 14, a middle outlet 15, a lower outlet 16 and a bottom outlet 17 from top to bottom, which are used to output naphtha, aviation kerosene, diesel and tail oil respectively.

[0010] The working principle of this hydrocracking system is as follows:

[0011] The 364°C straight-run wax oil from the high-pressure heat exchanger first flows into the raw material inlet pipeline 9, and then flows into the raw material tank 2 after being filtered by the raw material oil filter 1; then, it is mixed with the circulating hydrogen compressed by the circulating hydrogen compressor 5 and heated to 473°C by the circulating hydrogen heating furnace 4 to form a 375°C mixture and then sent to the top of the reactor 6; after that, after the reaction of the three refining beds and the two cracking beds in the reactor 6, the impurities such as sulfur and nitrogen in the mixture are removed, and the macromolecules in the straight-run wax oil are cracked into smaller molecules, and finally the 407°C product mixture flows into the mixing pipeline 12 from the lower end of the reactor 6, and then the product mixture is cooled by heat exchange and flashed, and the circulating hydrogen flows into the circulating hydrogen pipeline 11 through the gas pipeline for circulation and participates in the reaction again, and the liquid mixed product enters the separator 7 through the liquid pipeline for further product separation;

[0012] The liquid mixed product is first stripped in the separator 7 to remove the sulfur-containing gas, and then heated in the fractionation tower feed heating furnace before entering the lower part of the fractionation tower 8. After the gas-liquid phase exchange of the multi-layer trays in the fractionation tower 8, naphtha, aviation kerosene, diesel and tail oil are output from the upper outlet 14, the middle outlet 15, the lower outlet 16 and the bottom outlet 17 respectively, wherein naphtha is the top product, including light naphtha and heavy naphtha, aviation kerosene and diesel are middle fractions, and tail oil is a heavy fraction. The yield distribution of the above products is as follows:

[0013] Light naphtha 4.68%; heavy naphtha 21%; aviation kerosene 30%; diesel 35.54%; tail oil 1.8%.

[0014] However, the yields of various products of the above-mentioned hydrocracking system cannot be flexibly adjusted according to market demand, and the yield of low-end product diesel is as high as about 35%, while the yield of high-end product aviation kerosene is only 30%, so it needs to be modified. Summary of the invention

[0015] In order to solve the above problems, the object of the present invention is to provide a hydrocracking system for increasing the production of aviation kerosene.

[0016] In order to achieve the above-mentioned purpose, the hydrocracking system for increasing the production of aviation kerosene provided by the present invention mainly comprises a raw material oil filter, a raw material tank, a high-pressure feed pump, a circulating hydrogen heating furnace, a circulating hydrogen compressor, a reactor, a separator and a fractionation tower; wherein, the raw material inlet pipeline from the high-pressure heat exchanger is connected to the middle part of the raw material tank; the two ends of the raw material outlet pipeline are respectively connected to the bottom of the raw material tank and the top of the reactor; the inlet and outlet of the raw material oil filter are connected to the raw material inlet pipeline; the inlet and outlet of the high-pressure feed pump are connected to the raw material outlet pipeline; the two ends of the circulating hydrogen pipeline are respectively connected to the top of the reactor and the separator; the inlet pipeline of the circulating hydrogen compressor is connected to the top of the separator, and the outlet pipeline is connected to the circulating hydrogen heating furnace; The outlet pipeline of the annular hydrogen heating furnace is connected to the top of the reactor; one end of the mixing pipeline is connected to the lower end of the reactor, and the other end is connected to the tube side inlet of the high-pressure heat exchanger; one end of the tube side outlet pipeline of the high-pressure heat exchanger is connected to the tube side outlet of the high-pressure heat exchanger, and the other end is connected to the middle of the separator; one end of the separator outlet pipeline is connected to the lower end of the separator, and the other end is connected to the lower part of the fractionation tower; the fractionation tower is provided with an upper outlet, a middle outlet, a lower outlet and a bottom outlet from top to bottom, respectively used for outputting naphtha, aviation kerosene, diesel and tail oil; the hydrocracking system for increasing the production of aviation kerosene also includes a diesel circulation pipeline whose two ends are respectively connected to the raw material inlet pipeline and the lower outlet of the fractionation tower.

[0017] One end of the diesel circulation pipeline is connected to the raw material inlet pipeline located before the raw material oil filter, or is connected to the raw material inlet pipeline located after the raw material oil filter.

[0018] A valve is installed on the diesel circulation pipeline.

[0019] The hydrocracking system for increasing the production of aviation kerosene provided by the present invention has the following beneficial effects:

[0020] The present invention flexibly solves the problem of enterprises whose target products are aviation kerosene in certain time periods. By adding a diesel recycling process for the fractionation part of the product, the system's self-produced diesel is fully recycled and reacted to crack again, and the target product is changed from the maximum production of middle distillate oil to the high production of aviation kerosene. The product types remain unchanged, and the product yield is adjusted, so that the enterprise can adjust its business strategy and respond to the market more actively, truly achieving the purpose of the enterprise being guided by market demand and serving production and operation. It has the characteristics of small transformation engineering, low investment, flexible diesel cracking until there is no diesel product, and high aviation kerosene yield, and is particularly suitable for oil refining enterprises with low hydrocracking processing load to increase the production of aviation kerosene. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic diagram of a hydrocracking system of prior art.

[0022] Figure 2 The present invention is a schematic diagram of the hydrocracking system for increasing the production of aviation kerosene. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The same components as those in the prior art are given the same reference numerals.

[0024] like Figure 2 As shown, the hydrocracking system for increasing the production of aviation kerosene provided by the present invention mainly comprises a feedstock oil filter 1, a feedstock tank 2, a high-pressure feed pump 3, a circulating hydrogen heating furnace 4, a circulating hydrogen compressor 5, a reactor 6, a separator 7 and a fractionation tower 8; wherein, a feedstock inlet pipeline 9 from the high-pressure heat exchanger is connected to the middle of the feedstock tank 2; both ends of a feedstock outlet pipeline 10 are respectively connected to the bottom of the feedstock tank 2 and the top of the reactor 6; the inlet and outlet of the feedstock oil filter 1 are connected to the feedstock inlet pipeline 9; the inlet and outlet of the high-pressure feed pump 3 are connected to the feedstock outlet pipeline 10; both ends of a circulating hydrogen pipeline 11 are respectively connected to the top of the reactor 6 and the separator 7; the inlet pipeline of the circulating hydrogen compressor 5 is connected to the top of the separator 7, and the outlet pipeline is connected to the circulating hydrogen heating furnace 4, and the circulating hydrogen heating furnace 4 is connected to the top of the reactor 6; one end of the mixing pipeline 12 is connected to the lower end of the reactor 6, and the other end is connected to the tube side inlet of the high-pressure heat exchanger 20; one end of the high-pressure heat exchanger tube side outlet pipeline 21 is connected to the tube side outlet of the high-pressure heat exchanger 20, and the other end is connected to the middle of the separator 7; one end of the separator outlet pipeline 13 is connected to the lower end of the separator 7, and the other end is connected to the lower part of the fractionation tower 8; the fractionation tower 8 is provided with an upper outlet 14, a middle outlet 15, a lower outlet 16 and a bottom outlet 17 from top to bottom, respectively, for outputting naphtha, aviation kerosene, diesel and tail oil; the hydrocracking system for increasing the production of aviation kerosene also includes a diesel circulation pipeline 18 whose two ends are respectively connected to the raw material inlet pipeline 9 and the lower outlet 16 of the fractionation tower 8.

[0025] One end of the diesel circulation pipeline 18 is connected to the raw material inlet pipeline 9 located in front of the raw material oil filter 1, or connected to the raw material inlet pipeline 9 located behind the raw material oil filter 1. If the raw material oil filter 1 has sufficient backwashing capacity, one end of the diesel circulation pipeline 18 can be connected in front of the raw material oil filter 1 to ensure clean feed; if the backwashing capacity of the raw material oil filter 1 is insufficient, one end of the diesel circulation pipeline 18 can also be connected after the raw material oil filter 1, but during operation, it is necessary to pay close attention to the pressure difference change of the raw material oil filter 1, the vibration, displacement and other parameters of the high-pressure feed pump 3.

[0026] A valve 19 is installed on the diesel circulation pipeline 18 .

[0027] The working principle of the hydrocracking system for increasing the production of aviation kerosene provided by the present invention is described as follows:

[0028] When it is necessary to increase the yield of aviation kerosene, open the valve 19 on the diesel circulation pipeline 18; the straight-run wax oil from the high-pressure heat exchanger flows into the raw material inlet pipeline 9. If one end of the diesel circulation pipeline 18 is connected before the raw material oil filter 1, the straight-run wax oil will be mixed with the diesel from the lower outlet 16 of the fractionating tower 8 and output through the diesel circulation pipeline 18, and then the temperature will be adjusted to 303°C, and then it will flow into the raw material tank 2 after being filtered by the raw material oil filter 1; if one end of the diesel circulation pipeline 18 is connected after the raw material oil filter 1, the straight-run wax oil will be filtered by the raw material oil filter 1, and then it will be mixed with the diesel from the lower outlet 16 of the fractionating tower 8 and output through the diesel circulation pipeline 18, and then the temperature will be adjusted to 303°C and then flow into the raw material tank 2; then The mixture is then mixed with the circulating hydrogen compressed by the circulating hydrogen compressor 5 and heated to 484°C by the circulating hydrogen heating furnace 4 to form a mixture at 357°C and then fed into the top of the reactor 6; after the reaction of the three refining beds and two cracking beds in the reactor 6, the impurities such as sulfur and nitrogen in the mixture are removed, and the macromolecules in the straight-run wax oil are cracked into smaller molecules. Finally, the product mixture at 393°C flows into the mixing pipeline 12 from the lower end of the reactor 6. After the product mixture is cooled by heat exchange and flashed, the circulating hydrogen flows into the circulating hydrogen pipeline 11 through the gas pipeline for circulation and participates in the reaction again, and the liquid mixed product enters the separator 7 through the liquid pipeline for further product separation;

[0029] The liquid mixed product is first stripped in the separator 7 to remove the sulfur-containing gas, and then heated in the fractionation tower feed heating furnace before entering the lower part of the fractionation tower 8. After the gas-liquid phase exchange of the multi-layer tray in the fractionation tower 8, naphtha, aviation kerosene, diesel and tail oil are respectively output from the upper outlet 14, the middle outlet 15, the lower outlet 16 and the bottom outlet 17, wherein naphtha is the top product, including light naphtha and heavy naphtha, aviation kerosene and diesel are the middle fractions, and the tail oil is the heavy fraction. The product diesel is no longer shipped as a product alone, but the product diesel is recycled back to the raw material import pipeline 9 and used as a new raw material oil of the system, so that the product diesel is cracked again to realize the splitting of the diesel component into the aviation kerosene component and other light components. If the market demand for product diesel is large, the valve 19 on the diesel circulation pipeline 18 can be closed to restore the production process of the original system.

[0030] The yields of the above products are distributed as follows:

[0031] Light naphtha 1.65%; heavy naphtha 19.9%; aviation kerosene 46.83%; diesel 14.78%; tail oil 0.37%.

[0032] Through the technical transformation of the present invention, the hydrocracking system for increasing the production of aviation kerosene provided by the present invention achieves the purpose of increasing the production of aviation kerosene under low load. Compared with before the transformation, the aviation kerosene yield is increased from 30% to 46.83%, and the diesel yield can be flexibly reduced until the yield can be reduced to 0.

[0033] The following points should be noted when implementing the hydrocracking system for increasing the production of aviation kerosene provided by the present invention:

[0034] a. Pay attention to the temperature of the diesel product extraction site. This temperature should not be too high to prevent cavitation at the inlet of the high-pressure feed pump.

[0035] b. Since diesel is recycled back to the raw material, the mixed feed components become lighter, the reaction products become lighter overall, and the overall heat load of the system changes greatly. Heat exchange calculation is required to prevent corrosion problems after the temperature drops.

[0036] c. After the feed components become lighter, the cracking reaction in the reactor bed is easier to proceed. Attention should be paid to the control of the reaction temperature at normal times to prevent over-temperature accidents.

[0037] d. When the feed component becomes lighter and the target product is aviation kerosene, the cracking depth increases, the light component yield increases accordingly, the light component amount becomes larger, and the residence time in the cold high fraction and cold low fraction is shortened accordingly. More stable control is required to prevent emergency shutdown of the device due to liquid carried by circulating hydrogen.

[0038] In addition, the transformation of this system needs to be rigorously simulated and calculated to prevent hydraulic mismatch, heat imbalance, and equipment and facility capacity mismatch. Since the specific details of each hydrocracking unit are different, when mismatch occurs, the corresponding process and equipment and facilities need to be synchronously transformed in order to achieve the ultimate goal of increasing the production of aviation kerosene.

Claims

1. A hydrocracking system for increasing the production of aviation kerosene, mainly comprising a feed oil filter (1), a feed tank (2), a high-pressure feed pump (3), a circulating hydrogen heating furnace (4), a circulating hydrogen compressor (5), a reactor (6), a separator (7), a fractionation tower (8) and a high-pressure heat exchanger (20); wherein: The raw material inlet pipeline (9) from the high-pressure heat exchanger is connected to the middle of the raw material tank (2); the two ends of the raw material outlet pipeline (10) are respectively connected to the bottom of the raw material tank (2) and the top of the reactor (6); the inlet and outlet of the raw material oil filter (1) are connected to the raw material inlet pipeline (9); the inlet and outlet of the high-pressure feed pump (3) are connected to the raw material outlet pipeline (10); the two ends of the circulating hydrogen pipeline (11) are respectively connected to the top of the reactor (6) and the separator (7); the inlet pipeline of the circulating hydrogen compressor (5) is connected to the top of the separator (7), and the outlet pipeline is connected to the circulating hydrogen heating furnace (4), and the outlet pipeline of the circulating hydrogen heating furnace (4) is connected to the top of the reactor (6); one end of the mixing pipeline (12) is connected to the lower end of the reactor (6), and the other end is connected to the At the tube side inlet of the high-pressure heat exchanger (20); one end of the high-pressure heat exchanger tube side outlet pipeline (21) is connected to the tube side outlet of the high-pressure heat exchanger (20), and the other end is connected to the middle of the separator (7); one end of the separator outlet pipeline (13) is connected to the lower end of the separator (7), and the other end is connected to the lower part of the fractionation tower (8); the fractionation tower (8) is provided with an upper outlet (14), a middle outlet (15), a lower outlet (16) and a bottom outlet (17) from top to bottom, respectively used to output naphtha, aviation kerosene, diesel and tail oil; it is characterized in that: the hydrocracking system for increasing the production of aviation kerosene also includes a diesel circulation pipeline (18) whose two ends are respectively connected to the raw material inlet pipeline (9) and the lower outlet (16) of the fractionation tower (8).

2. The hydrocracking system for increasing the production of aviation kerosene according to claim 1, characterized in that: One end of the diesel circulation pipeline (18) is connected to the raw material inlet pipeline (9) located before the raw material oil filter (1), or connected to the raw material inlet pipeline (9) located after the raw material oil filter (1).

3. The hydrocracking system for increasing the production of aviation kerosene according to claim 1, characterized in that: A valve (19) is installed on the diesel circulation pipeline (18).

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