Application of a low-temperature catalyst in a full-fraction crude benzene hydrogenation unit

Abstract

The present invention discloses a kind of application of low temperature catalyst in full-fraction crude benzene hydrogenation device, including a low temperature hydrogenation reactor, a low temperature hydrogenation reactor inlet heat exchanger, a low temperature hydrogenation reactor outlet heat exchanger composed of a low temperature hydrogenation reaction system, the input port of the low temperature hydrogenation reactor is connected to the low temperature hydrogenation reactor inlet heat exchanger, and the output port of the low temperature hydrogenation reactor is connected to the low temperature hydrogenation reactor outlet heat exchanger; specifically applied as follows: the low temperature hydrogenation reaction system is arranged in the previous step process of the pre-hydrogenation reactor, and crude benzene and diluent oil enter the low temperature hydrogenation reactor at a hydrogen pressure of 3.0-4.0MPa and a temperature of 85°C-95°C; after mixing with hydrogen, the feedstock oil sequentially enters the low temperature hydrogenation reactor inlet heat exchanger, the low temperature hydrogenation reactor, the low temperature hydrogenation reaction system composed of the low temperature hydrogenation reactor outlet heat exchanger, and the present invention relates to the technical field of full-fraction crude benzene hydrogenation process. The present invention solves the problem that the start-up cycle of the pre-hydrogenation reactor is short.

Description

Technical Field

[0001] The invention relates to the technical field of full-fraction crude benzene hydrogenation technology, in particular to the application of a low-temperature catalyst in a full-fraction crude benzene hydrogenation device. Background Art

[0002] In the existing full-fraction crude benzene hydrogenation unit, crude benzene and diluent oil enter the pre-hydrogenation reactor at a hydrogen pressure of 3.0-4.0 MPa and a temperature of 160°C to remove diolefins and styrene, and then enter the main hydrogenation reactor for desulfurization, denitrogenation and olefin saturation reactions. The refined crude benzene produced is then separated into benzene, toluene, heavy aromatics and non-aromatic products through extraction and distillation.

[0003] Crude benzene feedstock contains unstable compounds, primarily linear and cyclic olefins with one or two double bonds, such as diolefins, cycloolefins, cyclodienes, styrene, and indene. During the crude benzene hydrogenation process, these unsaturated compounds easily polymerize upon heating to form high-molecular-weight, resinous colloids, which adhere to various heat exchange equipment, furnaces, pipelines, and catalyst beds, causing blockage. Because the full-fraction hydrogenation process does not remove heavy components from the feedstock, some of these heavy components rapidly coke when entering the pre-hydrogenation reactor at 150-160°C. This coking, primarily from diolefins and cycloolefins, polymerizes, causing coking. This causes a rapid increase in the pre-hydrogenation reactor's pressure drop, resulting in a startup cycle of only 40-50 days for a set of pre-hydrogenation reactors. This short startup cycle keeps the annual operating days of the unit low. However, due to the rapid increase in pressure drop caused by coking, processing capacity decreases after a period of operation, increasing the cost per unit of crude benzene processing. Each maintenance visit also increases maintenance costs, catalyst screening losses, and safety risks during maintenance. In order to achieve the ideal economic benefits of the full-fraction crude benzene hydrogenation process, it is necessary to find a way to extend the start-up cycle. Summary of the Invention

[0004] In order to solve the problem of short start-up period of pre-hydrogenation reactor, the present invention aims to provide a low-temperature catalyst for use in a full-fraction crude benzene hydrogenation unit.

[0005] To achieve the above object, the present invention adopts the following technical solution: an application of a low-temperature catalyst in a full-fraction crude benzene hydrogenation unit, comprising a low-temperature hydrogenation reaction system consisting of a low-temperature hydrogenation reactor, a low-temperature hydrogenation reactor inlet heat exchanger, and a low-temperature hydrogenation reactor outlet heat exchanger, wherein the input port of the low-temperature hydrogenation reactor is connected to the low-temperature hydrogenation reactor inlet heat exchanger, and the output port of the low-temperature hydrogenation reactor is connected to the low-temperature hydrogenation reactor outlet heat exchanger;

[0006] Specific applications are:

[0007] The low-temperature hydrogenation reaction system is set in the previous process of the pre-hydrogenation reactor. Crude benzene and diluent oil enter the low-temperature hydrogenation reactor at a hydrogen pressure of 3.0-4.0 MPa and a temperature of 85℃-95℃.

[0008] After the feedstock oil and hydrogen are mixed, they sequentially enter the low-temperature hydrogenation reactor inlet heat exchanger, the low-temperature hydrogenation reactor, and the low-temperature hydrogenation reactor outlet heat exchanger, which are composed of the low-temperature hydrogenation reactor inlet heat exchanger;

[0009] The low-temperature hydrogenation catalytic reactor is filled in five layers, including a first bed layer, a second bed layer, a third bed layer, a fourth bed layer and a fifth bed layer which are arranged in sequence from top to bottom.

[0010] Preferably, after the feedstock oil is mixed with hydrogen, it is first heated to above 85°C in the heat exchanger at the inlet of the low-temperature hydrogenation reactor, enters the low-temperature hydrogenation reactor, and undergoes a preliminary olefin hydrogenation saturation reaction therein. It then enters the outlet heat exchanger of the low-temperature hydrogenation reactor to be heated to the temperature required by the subsequent reaction system before exiting the low-temperature hydrogenation reaction system.

[0011] Preferably, the first bed layer is filled with FBN bird's nest hydrogenation protective agent with a filling height of 1055-1159 mm. The FBN bird's nest hydrogenation protective agent is based on activated alumina as a carrier, molybdenum (Mo) and nickel (Ni) as active components, and is made by impregnation, drying and sintering processes. It has a bird's nest honeycomb shape as the main body and has the ability to intercept micro impurities, accommodate scale and effectively demetallize areas.

[0012] Preferably, the second bed is filled with JTH-1 catalyst, containing 25% nickel, with a black clover shape, a diameter of 2.5-3.5mm, and a bulk density of 0.78-0.82Kg / m 3 High nickel catalyst, filling height 2950-3050mm.

[0013] Preferably, the third bed is filled with JTH-2 catalyst, containing 40% nickel, in the form of a black cylinder with a diameter of 4.5-6.5 mm and a bulk density of 0.9-1.1 kg / m 3 High nickel catalyst, filling height 551-653mm.

[0014] Preferably, the fourth bed layer is filled with φ6 porcelain balls with a filling height of 82-115 mm.

[0015] Preferably, the fifth bed layer is filled with φ13 porcelain balls with a filling height of 91-113 mm.

[0016] Preferably, the volume purity of hydrogen used in the low-temperature hydrogenation reactor is greater than or equal to 99.5%.

[0017] Preferably, the volume space velocity of the low temperature hydrogenation reactor is 3.2h -1 .

[0018] Preferably, the olefin saturation reaction occurs under the action of JTH-1 high nickel catalyst and JTH-2 high nickel catalyst:

[0019] C2H2+H2=C2H4;

[0020] C n H 2n +H2=C n H 2n+2 ;

[0021] C n H 2n-2 +2H2=C n H 2n+2 .

[0022] Compared with the prior art, the present invention achieves the following beneficial effects: crude benzene reacts in the liquid phase in the low-temperature hydrogenation reactor, the reaction releases little heat, and the pre-hydrogenation reaction can be carried out at a lower reaction temperature, so that the unsaturated compounds in the crude benzene, mainly diolefins and cycloolefins, participate more in the hydrogenation saturation reaction, while polymerization reaction rarely occurs; the content of unsaturated compounds, diolefins and cycloolefins, in the raw materials after the reaction in the low-temperature hydrogenation reaction system is reduced to below 0.1%, and the polymerization reaction in the subsequent reaction system is greatly reduced, thereby achieving the purpose of suppressing coking and extending the continuous operation cycle of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0024] Figure 1 is a schematic diagram of a low-temperature hydrogenation reaction system of the present invention;

[0025] Figure 2 This is a schematic diagram of the loading of the low-temperature hydrogenation catalytic reactor of the present invention. DETAILED DESCRIPTION

[0026] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0027] See also Figure 1-2. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0028] Example 1: Application of a low-temperature catalyst in a full-range crude benzene hydrogenation unit, comprising two heat exchangers and a reactor, for use in a full-range crude benzene hydrogenation unit. The application to the full-range crude benzene hydrogenation unit involves a low-temperature hydrogenation catalytic reactor positioned upstream of the pre-hydrogenation reactor in the full-range crude benzene hydrogenation unit. The low-temperature hydrogenation reactor is loaded in five layers, with the first layer filled with bird's nest protective agent (FBN) at a height of 1100 mm. The low-temperature hydrogenation reactor is loaded in five layers, with the second layer filled with JTH-1 high-nickel catalyst at a height of 3000 mm. The low-temperature hydrogenation reactor is loaded in five layers, with the third layer filled with JTH-2 high-nickel catalyst at a height of 600 mm. The low-temperature hydrogenation reactor is loaded in five layers, with the fourth layer filled with φ6 ceramic balls at a height of 100 mm. The low-temperature hydrogenation reactor is loaded in five layers, with bed 5 filled with φ13 ceramic balls at a height of 100 mm.

[0029] Example 2, a process for applying a low-temperature catalyst in a full-fraction crude benzene hydrogenation unit. The application process is to set up a group of low-temperature hydrogenation catalytic reactors in front of the pre-hydrogenation reactor. Crude benzene and diluent oil enter the low-temperature hydrogenation reactor at a hydrogen pressure of 3.0-4.0 MPa and a temperature of 85°C-95°C, so that the full-fraction crude benzene hydrogenation unit can be started up for more than three months. The low-temperature hydrogenation catalytic reactor is filled with 5 layers. The first bed is filled with FBN bird's nest hydrogenation protective agent. FBN bird's nest hydrogenation protective agent uses activated alumina as a carrier and molybdenum (Mo) and nickel (Ni) as active components. It is made by impregnation, drying, and calcination. It has a bird's nest honeycomb shape as the main body and has the ability to intercept micro impurities, accommodate scale and effectively remove metal areas. The second bed is filled with JTH-1 catalyst, a catalyst containing 25% nickel, with a black clover shape, a diameter of 2.5-3.5mm, and a bulk ratio of 0.78-0.82Kg / m 3 The third bed is filled with JTH-2 catalyst, a black cylindrical catalyst with a nickel content of 40%, a diameter of 4.5-6.5mm, and a bulk density of 0.9-1.1Kg / m 3The fourth bed is filled with φ6 ceramic balls. The fifth bed is filled with φ13 ceramic balls.

[0030] The low-temperature hydrogenation reactor is filled in 5 layers, the first bed is filled with bird's nest protective agent FBN, and the filling height is 1100 mm.

[0031] The low-temperature hydrogenation reactor is filled in 5 layers, the second bed is filled with JTH-1 high-nickel catalyst, and the filling height is 3000 mm.

[0032] The low-temperature hydrogenation reactor is filled in 5 layers, the third bed is filled with JTH-2 high-nickel catalyst, and the filling height is 600 mm.

[0033] The low-temperature hydrogenation reactor is filled in 5 layers, and the fourth bed is filled with φ6 porcelain balls with a filling height of 100 mm.

[0034] The low-temperature hydrogenation reactor is filled in 5 layers, with bed layer 5 filled with φ13 porcelain balls and a filling height of 100 mm.

[0035] The low-temperature hydrogenation reactor uses two high-nickel catalysts, JTH-1 high-nickel catalyst and JTH-2 high-nickel catalyst, which are loaded in a ratio of 5:1.

[0036] A low-temperature hydrogenation reactor inlet heat exchanger is provided before the low-temperature hydrogenation reactor to control the temperature inside the low-temperature hydrogenation reactor at 85°C-95°C.

[0037] The hydrogen and the raw oil are premixed before the heat exchanger at the inlet of the low-temperature hydrogenation reactor.

[0038] The hydrogen used in the low-temperature hydrogenation reactor is fresh hydrogen with a volume purity greater than or equal to 99.5%.

[0039] The volumetric space velocity of the low-temperature hydrogenation reactor is 3.2h -1 .

[0040] The temperature in the low-temperature hydrogenation reactor is controlled at 85°C-95°C, and olefin saturation reaction occurs under the action of JTH-1 high-nickel catalyst and JTH-2 high-nickel catalyst:

[0041] C2H2+H2=C2H4

[0042] C n H 2n +H2=C n H 2n+2

[0043] C n H 2n-2 +2H2=C n H 2n+2

[0044] The temperature in the low-temperature hydrogenation reactor is controlled at 85°C-95°C, and olefin saturation reaction occurs under the action of JTH-1 high-nickel catalyst and JTH-2 high-nickel catalyst, and the following polymerization reaction is not likely to occur:

[0045] nC2H2+H2=polymer

[0046] C4H6+nC2H2+H2=polymer

[0047] mC2H2+nC2H2+H2=polymer

[0048] nC2H2=polymer

[0049] nC3H4=polymer

[0050] nC3H6=polymer

[0051] nC4H6=polymer

[0052] Example 3, a low-temperature catalyst is used in a full-fraction crude benzene hydrogenation unit, comprising a low-temperature hydrogenation reaction system consisting of a low-temperature hydrogenation reactor, a low-temperature hydrogenation reactor inlet heat exchanger, and a low-temperature hydrogenation reactor outlet heat exchanger, wherein the input port of the low-temperature hydrogenation reactor is connected to the low-temperature hydrogenation reactor inlet heat exchanger, and the output port of the low-temperature hydrogenation reactor is connected to the low-temperature hydrogenation reactor outlet heat exchanger;

[0053] Specific applications are:

[0054] The low-temperature hydrogenation reaction system is set in the previous process of the pre-hydrogenation reactor. Crude benzene and diluent oil enter the low-temperature hydrogenation reactor at a hydrogen pressure of 3.0-4.0 MPa and a temperature of 85℃-95℃.

[0055] After the feedstock oil and hydrogen are mixed, they sequentially enter the low-temperature hydrogenation reactor inlet heat exchanger, the low-temperature hydrogenation reactor, and the low-temperature hydrogenation reactor outlet heat exchanger, which are composed of the low-temperature hydrogenation reactor inlet heat exchanger;

[0056] The low-temperature hydrogenation catalytic reactor is filled in five layers, including a first bed layer, a second bed layer, a third bed layer, a fourth bed layer and a fifth bed layer which are arranged in sequence from top to bottom.

[0057] After the crude oil is mixed with hydrogen, it is first heated to above 85°C in the heat exchanger at the inlet of the low-temperature hydrogenation reactor, enters the low-temperature hydrogenation reactor, and undergoes a preliminary olefin hydrogenation saturation reaction. It then enters the outlet heat exchanger of the low-temperature hydrogenation reactor to heat up to the temperature required by the subsequent reaction system before leaving the low-temperature hydrogenation reaction system.

[0058] Crude benzene reacts in the liquid phase in the low-temperature hydrogenation reactor, which produces little reaction heat. Pre-hydrogenation reaction can be carried out at a lower reaction temperature, so that the unsaturated compounds in the crude benzene, mainly diolefins and cycloolefins, participate more in the hydrogenation saturation reaction, while polymerization reaction rarely occurs. The content of unsaturated compounds, diolefins and cycloolefins, in the raw materials after reaction in the low-temperature hydrogenation reaction system drops to below 0.1%, and the polymerization reaction in the subsequent reaction system is greatly reduced, thereby suppressing coking and extending the continuous operation cycle of the device.

[0059] The first bed layer is filled with FBN bird's nest hydrogenation protective agent with a filling height of 1055-1159mm. FBN bird's nest hydrogenation protective agent uses activated alumina as a carrier and molybdenum (Mo) and nickel (Ni) as active components. It is made by impregnation, drying and sintering process. It has a bird's nest honeycomb shape as the main body and has the ability to intercept micro impurities, accommodate scale and effectively demetallize the area.

[0060] The second bed is filled with JTH-1 catalyst, containing 25% nickel, with a black clover shape, a diameter of 2.5-3.5mm, and a bulk density of 0.78-0.82Kg / m 3 High nickel catalyst, filling height 2950-3050mm.

[0061] The third bed is filled with JTH-2 catalyst, which contains 40% nickel and is in the form of a black cylinder with a diameter of 4.5-6.5 mm and a bulk density of 0.9-1.1 kg / m 3 High nickel catalyst, filling height 551-653mm.

[0062] The fourth bed layer is filled with φ6 porcelain balls with a filling height of 82-115mm.

[0063] The fifth bed layer is filled with φ13 porcelain balls with a filling height of 91-113 mm.

[0064] The volume purity of hydrogen used in the low-temperature hydrogenation reactor is greater than or equal to 99.5%.

[0065] The volumetric space velocity of the low-temperature hydrogenation reactor is 3.2h -1 .

[0066] Olefin saturation reaction occurs under the action of JTH-1 high nickel catalyst and JTH-2 high nickel catalyst:

[0067] C2H2+H2=C2H4;

[0068] C n H 2n +H2=C n H 2n+2 ;

[0069] C n H 2n-2+2H2=C n H 2n+2。

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An application of a low-temperature catalyst in a full-fraction crude benzene hydrogenation unit, comprising a low-temperature hydrogenation reaction system consisting of a low-temperature hydrogenation reactor, a low-temperature hydrogenation reactor inlet heat exchanger, and a low-temperature hydrogenation reactor outlet heat exchanger, characterized in that: The input port of the low-temperature hydrogenation reactor is connected to the inlet heat exchanger of the low-temperature hydrogenation reactor, and the output port of the low-temperature hydrogenation reactor is connected to the outlet heat exchanger of the low-temperature hydrogenation reactor; the specific application is: The low-temperature hydrogenation reaction system is set in the previous process of the pre-hydrogenation reactor. Crude benzene and diluent oil enter the low-temperature hydrogenation reactor at a hydrogen pressure of 3.0-4.0 MPa and a temperature of 85℃-95℃. After the feedstock oil and hydrogen are mixed, they sequentially enter the low-temperature hydrogenation reactor inlet heat exchanger, the low-temperature hydrogenation reactor, and the low-temperature hydrogenation reactor outlet heat exchanger, which are composed of the low-temperature hydrogenation reactor inlet heat exchanger; The low-temperature hydrogenation catalytic reactor is filled in 5 layers, including a first bed layer, a second bed layer, a third bed layer, a fourth bed layer and a fifth bed layer arranged in sequence from top to bottom; After mixing with hydrogen, the crude oil is first heated to above 85°C in a heat exchanger at the inlet of a low-temperature hydrogenation reactor, enters the low-temperature hydrogenation reactor, undergoes a preliminary olefin hydrogenation saturation reaction, and then enters a heat exchanger at the outlet of the low-temperature hydrogenation reactor to be heated to the temperature required by the subsequent reaction system before exiting the low-temperature hydrogenation reaction system. The first bed is filled with FBN bird's nest hydrogenation protective agent, with a filling height of 1055-1159 mm. The FBN bird's nest hydrogenation protective agent uses activated alumina as a carrier and molybdenum (Mo) and nickel (Ni) as active components. It is manufactured through an impregnation, drying, and calcination process. Its main shape is a bird's nest honeycomb, which has the ability to intercept micro-impurities, accommodate scale, and effectively remove metal areas. The second bed is filled with JTH-1 catalyst, which contains 25% nickel and has a black clover leaf shape, a diameter of 2.5-3.5 mm, and a bulk density of 0.78-0.82 kg / m. 3 The third bed is filled with JTH-2 catalyst, which contains 40% nickel and is black cylindrical in shape, with a diameter of 4.5-6.5mm and a bulk density of 0.9-1.1Kg / m 3 The high nickel catalyst is filled at a height of 551-653 mm; the fourth bed is filled with φ6 porcelain balls at a height of 82-115 mm; the fifth bed is filled with φ13 porcelain balls at a height of 91-113 mm; the volume purity of hydrogen used in the low-temperature hydrogenation reactor is greater than or equal to 99.5%; the volume space velocity of the low-temperature hydrogenation reactor is 3.2 h -1 , olefin saturation reaction occurs under the action of JTH-1 high nickel catalyst and JTH-2 high nickel catalyst: C2H2+H2=C2H4; C n H 2n +H2=C n H 2n+2 ; C n H 2n-2 +2H2=C n H 2n+2 .

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