Hydrogenation reaction system
Technical Field
The invention relates to the field of oil refining chemical industry, in particular to a hydrogenation reaction system with a gas adsorption and separation unit.
Background
Along with the deterioration of crude oil, the upgrading of oil quality and the continuous improvement of environmental protection requirements. The demand of hydrogen in oil refining and chemical processes is increasing. The hydrogen is widely applied to the oil refining fields of hydrocracking, hydrofining, residual oil hydrogenation and the like, and is also applied to chemical processes of butanol-octanol, xylene isomerization and the like. The hydrogen gas plays an important role in producing low-sulfur, low-nitrogen and low-metal fuel oil while efficiently utilizing limited petroleum resources to the maximum extent, and has irreplaceable effects in ensuring long-period operation of a refining device and prolonging the service life of a catalyst.
In the refining hydrogenation process, the partial pressure of hydrogen in a system can be continuously reduced along with the hydrogenation reaction due to the fixed pressure of a hydrogenation system. In order to ensure the hydrogen partial pressure of the system, the method can be realized by two methods of supplementing new hydrogen and improving the purity of circulating hydrogen.
In a conventional hydrogenation system, the hydrogen partial pressure of the system is ensured by adopting a mode of discharging circulating hydrogen and increasing and supplementing new hydrogen. And after the pressure of the discharged circulating hydrogen is reduced, the discharged circulating hydrogen returns to a new hydrogen system again through a hydrogen purification device. The existing hydrogen purification technology cannot be directly integrated into the circulating hydrogen purification process due to the defects of the existing hydrogen purification technology in the aspects of operation pressure, occupied area, process control and the like.
In patent CN 1642860a, the method of feeding the flash vapor obtained from the high-pressure separator into an absorption zone is adopted to improve the purity of recycle hydrogen, the adopted method for improving the purity of recycle hydrogen is a solvent absorption method, the solvent absorption method has large occupied area, and needs to continuously regenerate the solvent and supplement fresh solvent, and the solvent absorption method has much higher operation cost than the adsorption separation method due to the adoption of a plurality of solution high-pressure pumps.
In patent CN 101348235a, a hydrogen recovery system is used to increase the hydrogen-rich gas obtained from the cold low-fraction separator, and the method used may be membrane separation or temperature/pressure swing adsorption.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a hydrogenation reaction system, which can purify recycle hydrogen in a device by arranging an adsorption separation unit and can be reused in the hydrogenation process, so that the discharge of the recycle hydrogen of the system can be cancelled, and simultaneously, the energy consumption caused by pressure reduction in the discharge process of the recycle hydrogen and pressure rise in the reuse process is eliminated.
The invention provides a hydrogenation reaction system which is provided with a reaction unit, a separation unit, a desulfurization unit, a circulating hydrogen separation tank, an adsorption separation unit and a compression unit; wherein:
the reaction unit is used for receiving raw oil and hydrogen, and the raw oil and the hydrogen are subjected to hydrogenation reaction in the reaction unit to obtain a material A;
the separation unit is used for receiving the material A from the reaction unit, and the gas-phase material B and the liquid-phase material C are obtained after the material A is separated;
the desulfurization unit is used for receiving the gas-phase material B from the separation unit and processing the gas-phase material B to obtain a gas-phase material D;
the circulating hydrogen separating tank is used for receiving the gas-phase material D from the desulfurization unit and processing the gas-phase material D to obtain a material E;
the adsorption separation unit is used for receiving the material E from the circulating hydrogen separation tank and processing the material E to obtain a material F;
the compression unit is used for adjusting the pressure of the material F from the adsorption separation device, and then the material F is mixed with the supplementary hydrogen and enters the hydrogenation reaction unit.
In the hydrogenation reaction system, the reaction unit is provided with more than one reactor, and the reactor can be one or more of a fixed bed hydrogenation reactor, a boiling bed hydrogenation reactor and a suspension bed hydrogenation reactor.
In the hydrogenation reaction system, the separation unit may adopt any one of devices capable of realizing gas-liquid separation in the existing hydrogenation technology, and generally comprises one or more of a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator and a cold low-pressure separator.
In the hydrogenation reaction system, the desulfurization unit can adopt one of devices capable of removing sulfides in the gas-phase material obtained by the separation unit in the prior art, such as one or more of amine liquid absorption desulfurization, membrane desulfurization, adsorption desulfurization and hypergravity desulfurization in the prior art.
In the hydrogenation reaction system, the adsorption separation unit comprises a shell, an upper sealing slide block, an upper cover plate, a lower sealing slide block, a lower cover plate and a driving device, wherein the shell comprises an inner shell and an outer shell, the inner shell and the outer shell form a concentric sleeve structure, N adsorption blocks (N is an integral multiple of 4) are arranged in a space between the inner shell and the outer shell, and the driving device is arranged in the inner shell; the upper end of the shell is connected with the upper sealing slide block, the upper sealing slide block is connected with the upper cover plate, the upper cover plate is provided with a raw material air inlet pipe and a desorption gas exhaust pipe, the lower end of the shell is connected with the lower sealing slide block, the lower surface of the lower sealing slide block is connected with the lower cover plate, the lower cover plate is provided with a product gas exhaust pipe and a forward-release boosting process connecting pipe, and two ports of the forward-release boosting process connecting pipe are respectively arranged between the raw material air inlet pipe and the desorption gas exhaust pipe.
In the adsorption separation unit, the raw material gas inlet pipe and the product gas exhaust pipe are in a vertical corresponding relationship and are on the same axis.
In the adsorption separation unit, the casing may have any one of a square, a cylinder, a rectangular parallelepiped, and the like, and is preferably a cylinder.
In the adsorption separation unit, the adsorption block may be a wedge, a cylinder, a rectangular parallelepiped or other polygonal body, preferably a cylinder.
In the adsorption separation unit, the adsorption blocks are uniformly arranged in the space between the inner shell and the outer shell.
In the adsorption separation unit, the upper sealing slider and the lower sealing slider have the same shape as the space between the inner casing and the outer casing.
In the adsorption separation unit, the upper sealing slide block and the lower sealing slide block are respectively provided with holes with the same number as the adsorption blocks, and the holes can be in the shapes of circles, ellipses, polygons and the like. The upper sealing slide block and the lower sealing slide block are used for accurately conveying the feed gas to the specified adsorption blocks and keeping independence between different adsorption blocks.
In the adsorption separation unit, the adsorption block is filled with an adsorption separation material. The adsorption separation material can be one or more of activated alumina adsorbent, silica gel adsorbent, activated carbon adsorbent and molecular sieve adsorbent.
In the adsorption separation unit, the driving device drives the shell, the upper sealing slide block and the lower sealing slide block to rotate according to a set program, and the rotation track is a concentric circle of the shell.
The driving device adopts a rotation control motor.
In the adsorption separation unit, the upper sealing slide block is used for accurately conveying the raw material gas to the adsorption blocks, and the upper sealing slide block and the lower sealing slide block keep independence between different adsorption blocks.
Among the above-mentioned adsorption and separation unit, in the same direction as put the process connecting pipe that steps up and be used for adsorbing the piece and be in the desorption regeneration after the desorption regeneration of the state of waiting to step up in the same direction as putting the absorption piece of state and be connected, will be in the same direction as the gassing of the absorption piece of putting the state through the aperture on the lower seal slider and directly discharge to the absorption piece after the regeneration that waits to step up, whole process does not need plus control valve to effectively reduce the loss of pressure of in-process.
In the adsorption separation unit, the product gas exhaust pipe is used for sending out purified gas obtained after treatment of the adsorption block, and an outlet of the product gas exhaust pipe is connected with a purified gas buffer tank so as to ensure the stability of output gas flow and pressure. In the present invention, the product gas is directly fed to a compression unit in the hydrogenation reaction system.
Compared with the prior art, the hydrogenation reaction system has the following advantages: (1) by adopting the highly integrated adsorption separation unit, the hydrogenation reaction system is reconstructed, and the in-situ purification of the recycle hydrogen in the hydrogenation reaction system is realized; (2) the discharge of recycle hydrogen in the original hydrogenation system is cancelled, and the utilization efficiency of the system hydrogen is improved; (3) due to the elimination of the discharge of the recycle hydrogen, the pressure reduction and the pressure increase after purification in the original discharge process of the recycle hydrogen are eliminated, thereby reducing the process energy consumption. The invention realizes the organic combination of the recycle hydrogen purification and the traditional hydrogenation reaction system, and effectively reduces the process complexity, the investment and the energy consumption.
Drawings
FIG. 1 is a schematic diagram of a hydrogenation reaction system according to the present invention.
FIG. 2 is a schematic view of the structure of the adsorption separation unit according to the present invention.
FIG. 3 is a schematic view of the internal structure of the adsorption separation unit.
Fig. 4 is a schematic structural diagram of an upper sealing slider.
Fig. 5 is a schematic structural view of a lower sealing slider.
Fig. 6 is a schematic view of the structure of the upper cover plate.
Fig. 7 is a schematic view of the structure of the lower cover plate.
Detailed Description
The hydrogenation reaction system of the present invention will be described in detail below. It is to be understood that the matter herein set forth is for the purpose of illustration and description only and is not intended to be limiting.
The hydrogenation reaction system of the present invention is further described with reference to the accompanying drawings, and as shown in fig. 1, the present invention provides a hydrogenation reaction system, which is provided with a reaction unit 11, a separation unit 12, a desulfurization unit 13, a recycle hydrogen separation tank 14, an adsorption separation unit 15, and a compression unit 16; the reaction unit 1 is used for receiving raw oil 17 and hydrogen 25, and the raw oil 17 and the hydrogen 25 are subjected to hydrogenation reaction in the reaction unit 11 to obtain a material A19; the separation unit 12 is used for receiving the material a19 from the reaction unit 11, and as shown in fig. 1, the separation unit comprises a hot high-pressure separator 121, a cold high-pressure separator 122, a hot low-pressure separator 123 and a cold low-pressure separator 124, wherein the material a19 is sequentially separated by four separators to obtain a gas-phase material B20 and a liquid-phase material C; the desulfurization unit 13 is used for receiving the gas-phase material B20 from the separation unit 12 and processing the gas-phase material B20 to obtain a gas-phase material D21; the recycle hydrogen separation tank 14 is used for receiving the gas-phase material D21 from the desulfurization unit 13 and processing the gas-phase material to obtain a material E22; the adsorption separation unit 15 is used for receiving the material E22 from the circulating hydrogen separation liquid tank 14 and obtaining a material F23 after treatment; the compression unit 16 is used for adjusting the pressure of the material F23 from the adsorption separation unit 15, and hydrogen 25 obtained after the material 24 with the adjusted pressure is mixed with the make-up hydrogen 18 enters the hydrogenation reaction unit 11.
As shown in fig. 2 to 7, the adsorption separation unit of the present invention includes a housing 1, an upper sealing slider 2, an upper cover plate 3, a lower sealing slider 4, a lower cover plate 5 and a driving device 6, where the housing 1 includes an inner housing 101 and an outer housing 102, the inner housing 101 and the outer housing 102 form a concentric sleeve structure, N adsorption blocks 103 (N is an integer multiple of 4) are disposed in a space between the inner housing 101 and the outer housing 102, and the adsorption blocks 103 are uniformly arranged in the space between the inner housing and the outer housing. The inner shell 101 is internally provided with a driving device 6, the driving device 6 drives the shell 1, the upper sealing slide block 2 and the lower sealing slide block 4 to rotate according to a set program, and the rotating track is a concentric circle of the shell. The upper end of the shell 1 is connected with the upper sealing slide block 2, holes 201 with the same quantity as the adsorption blocks 103 are formed in the upper sealing slide block 2, the holes 201 can be circular, oval, polygonal and the like, the upper sealing slide block 2 is connected with the upper cover plate 3, a raw material air inlet pipe 301 and a desorption gas exhaust pipe 302 are arranged on the upper cover plate 3, the lower end of the shell 1 is connected with the lower sealing slide block 4, holes 401 with the same quantity as the adsorption blocks 103 are formed in the lower sealing slide block 4, the holes 401 can be circular, oval, polygonal and the like, the lower surface of the lower sealing slide block 4 is connected with the lower cover plate 5, a product gas exhaust pipe 501 and a forward-releasing and boosting process connecting pipe 502 are arranged on the lower cover plate 5, and two ports of the forward-releasing and boosting process connecting pipe are respectively arranged between the raw material air inlet pipe 301 and. The raw material inlet pipe 301 and the product gas exhaust pipe 501 are in a corresponding relationship from top to bottom and are on the same axis.
In the above description of the present invention, the purified recycle hydrogen gas is the hydrogen-containing gas discharged from the cold high-pressure separator of the separation unit; the hydrogenation reaction system of the invention can also be used for purifying discharged hydrogen-containing gas from the cold low-pressure separator as recycle hydrogen. However, not all of the product separation units of the hydrogenation reaction system comprise the hot high-pressure separator, the cold high-pressure separator, the hot low-pressure separator and the cold low-pressure separator, which are described in the above description, and for the hydrogenation reaction system in which the separation units only comprise one or more of the separators, the system of the present invention can also purify the discharged hydrogen-containing gas to be returned to the reaction unit as the recycle hydrogen.
The following describes the operation process of the adsorption separation unit in a hydrogenation reaction system, and takes an example of filling 4 adsorption blocks between an inner shell and an outer shell, and the operation of the adsorption separation unit comprises the following steps:
(1) the adsorption separation unit receives a gas phase stream E22 from the recycle hydrogen separation liquid tank 14 as a unit raw material gas.
(2) Raw material gas (circulation hydrogen after taking off the liquid) enters into first absorption piece through raw material intake pipe 301 through the hole on the upper seal slider 2, and raw material gas top-down passes through the absorption piece, and the absorption piece adsorbs light hydrocarbon and other impurity in the raw material gas, improves circulation hydrogen purity simultaneously, and the hole through product gas exhaust pipe 501 discharge on the lower seal slider 4 of hydrogen after the purification, commodity circulation F23 promptly. The adsorbed impurities are adsorbed and stay on the adsorbing material in the adsorbing block;
(3) when the first adsorption block reaches a saturation state, the driving device drives the shell, the upper sealing slide block and the lower sealing slide block to rotate, the adsorption block which finishes the adsorption process enters a forward release state, and product gas remained in the adsorption block in the adsorption process is discharged into the regenerated adsorption block through a hole in the lower sealing slide block through a forward release and pressure boosting process connecting pipe to boost pressure of the regenerated adsorption block;
(4) and the adsorption block which finishes the sequential release process enters the desorption process, and the adsorption block which needs to be desorbed and regenerated is communicated with the desorption gas exhaust pipe 302 through a hole on the upper sealing slide block. The desorption gas is discharged from the adsorption block from bottom to top and is sent out of the device through a desorption gas exhaust pipe 302, namely the material flow 26. Obtaining a regenerated adsorption block after the desorption is finished;
(5) the driving device further rotates, the regeneration adsorption block enters a boosting process, and the regeneration adsorption block after boosting enters the next adsorption process;
(6) and (5) repeating the steps (2) to (6), so that the continuous operation of the device can be realized, and the circulating hydrogen gas can be continuously purified.
Example 1
In 50 million tons/year hydrocracking, VGO is used as a main raw material to produce middle distillate oil (jet fuel and diesel oil), and the operation pressure of the device is 10 MPa. The device is additionally provided with an adsorption separation unit after being improved, and adopts a hydrogenation system as shown in figure 1.
Before transformation, the new hydrogen molar concentration of the original device is 95 percent, the circulating hydrogen molar concentration is 78 percent, and the new hydrogen supplement amount is 20000Nm3H, circulating hydrogen quantity 50000Nm3The hydrogen-containing gas discharged from the high-pressure separator is 1200Nm3/h。
The device is adopted to transform the circulating hydrogen system, and after the transformation, the purity of the circulating hydrogen can be improved from 78 percent to 85 to 95 percent through the adsorption separation unit. The hydrogen recovery rate of the adsorption separation unit is 95-85%. Considering hydrogen recovery and system economics. Actual operation increased the recycle hydrogen purity to 88% at a hydrogen recovery of about 94%.
The new hydrogen supplement amount of the system is reduced by about 9 percent after the system is modified, the molar purity of the hydrogen-containing gas discharged out of the adsorption separation unit is about 28.5 percent, and the discharge amount is about 8340Nm3And/h, the effluent gas is 26 in FIG. 1. Before transformationThe hydrogen change of the latter system is shown in table 1 below.
TABLE 1 System Hydrogen Change before and after reforming
As can be seen from the above table, the amount of pure hydrogen saved after the modification is (20000-18200). + -. 0.95+936-2377=269Nm3H is used as the reference value. According to the hydrogen price of 1.2 yuan/Nm3And (4) calculating to obtain the annual economic benefit of about 271 ten thousand yuan. Economic losses due to pressure reduction during discharge of recycle hydrogen and pressure increase during recycling are not considered here.