Fractionation method for reducing vacuum fractionation load and application thereof

Abstract

The invention provides a fractionation method for reducing vacuum fractionation load and application thereof, and relates to the technical field of petrochemical engineering, and the fractionation method comprises the following steps: in the fractionation process, raw oil is firstly subjected to steam stripping and then is subjected to flash evaporation to obtain flash oil, and then the flash oil is subjected to vacuum fractionation, so that the vacuum fractionation load is reduced. According to the invention, the flash evaporation step is added between steam stripping and vacuum fractionation, and flash evaporation rapidly evaporates a part of light components under low pressure, so that the load of subsequent vacuum fractionation is reduced, the energy consumption and equipment requirements of a vacuum-pumping system are reduced, and the technical effect of reducing the gas phase load of the vacuum tower is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, in particular to a fractionation method for reducing vacuum fractionation load and application thereof. Background Art

[0002] The traditional distillation technology in the petroleum refining process, especially the distillation system for low-fraction oil in the hydrogenation unit, usually adopts steam stripping and vacuum distillation technology. Although it can effectively separate the light and heavy components in the low-fraction oil, it has problems such as high vacuum load, high energy consumption, complex equipment selection and large floor space.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a fractionation method for reducing the vacuum fractionation load, which is an energy-saving fractionation technology for oil products and can reduce the processing load of the vacuum system in the traditional fractionation system.

[0005] The second object of the present invention is to provide an application of a fractionation method for reducing the vacuum fractionation load, which is beneficial to reducing the energy consumption and equipment requirements of the vacuum system, and achieves the technical effect of reducing the gas phase load of the vacuum tower.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0007] In a first aspect, a fractionation method for reducing a vacuum fractionation load comprises the following steps:

[0008] In the fractionation process, the raw oil is first stripped and then flashed to obtain flash oil, which is then subjected to vacuum fractionation to reduce the vacuum fractionation load.

[0009] Furthermore, the raw oil includes low-fraction oil after hydrogenation.

[0010] Furthermore, the stripping method comprises the following steps:

[0011] The low-fraction oil after hydrogenation is passed into a stripping tower for stripping to remove light hydrocarbons and H2S components to obtain the stripping tower bottom oil.

[0012] Furthermore, the flash distillation method comprises the following steps:

[0013] The bottom oil of the stripping tower is introduced into a normal pressure separation tank for flash evaporation at 1 barg to obtain flash gas and flash oil.

[0014] Furthermore, the method of vacuum fractionation comprises the following steps:

[0015] Passing the flash oil into a vacuum tower for vacuum fractionation;

[0016] A vacuum pumping facility is provided on the top of the vacuum tower. The sideline oil of the vacuum tower enters the stripping tower and is stripped to a qualified flash point. After heat exchange and cooling, it exits the device.

[0017] In a second aspect, a fractionation method as described in any one of the above is used for low-oil separation.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The present invention provides a fractionation method for reducing the load of vacuum fractionation, which adds a flash evaporation step between steam stripping and vacuum fractionation to form a technical process of "stripping + flash evaporation + vacuum fractionation". Flash evaporation can reduce the load of subsequent vacuum fractionation by quickly evaporating some light components at a lower pressure, thereby reducing the energy consumption and equipment requirements of the vacuum system.

[0020] The application of the fractionation method for reducing the vacuum fractionation load provided by the present invention is conducive to reducing the energy consumption and equipment requirements of the vacuum system, achieving the technical effect of reducing the gas phase load of the vacuum tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A technical flow chart of "stripping + flash evaporation + vacuum fractionation" provided for one embodiment of the present invention.

[0023] Icons: 1-stripping tower; 2-stripping tower top air cooler; 3-stripping tower top water cooler; 4-stripping tower top reflux pump; 5-stripping tower top reflux tank; 6-flash system; 7-flash tank; 8-vacuum tower feed heat exchanger; 9-vacuum tower. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] According to a first aspect of the present invention, there is provided a fractionation method for reducing the vacuum fractionation load, comprising the following steps:

[0026] In the fractionation process, the raw oil is first stripped and then flashed to obtain flash oil, which is then subjected to vacuum fractionation to reduce the vacuum fractionation load.

[0027] The present invention adds a flash evaporation step between steam stripping and vacuum fractionation to form a technical process of "stripping + flash evaporation + vacuum fractionation". Flash evaporation can reduce the load of subsequent vacuum fractionation by quickly evaporating some light components at a lower pressure, thereby reducing the energy consumption and equipment requirements of the vacuum system.

[0028] In the present invention, the feedstock oil includes but is not limited to low-fraction oil after hydrogenation.

[0029] In a preferred embodiment, the method of stripping comprises the following steps:

[0030] The low-fraction oil after hydrogenation is passed into a stripping tower for stripping to remove light hydrocarbons and H2S components to obtain the stripping tower bottom oil.

[0031] In a preferred embodiment, the flash distillation method comprises the following steps:

[0032] The bottom oil of the stripping tower is passed into a normal pressure separation tank for flash evaporation at 1 barg to obtain flash gas and flash oil.

[0033] In the present invention, the method of vacuum fractionation comprises the following steps:

[0034] The flash oil is passed into a vacuum tower for vacuum fractionation;

[0035] Among them, a vacuum pumping facility can be installed on the top of the vacuum tower. The side line oil of the vacuum tower enters the stripping tower and is stripped to a qualified flash point, and then exits the device after heat exchange and cooling.

[0036] A typical fractionation method for reducing the vacuum fractionation load is shown in the flow chart. Figure 1 , including the following steps:

[0037] (a) Stripping to remove light hydrocarbons and H2S components:

[0038] The low-content oil after hydrogenation is passed through a stripping tower 1 to remove light hydrocarbons (C3, C4), H2S and other components. The bottom oil of the stripping tower enters a flash evaporation system 6 and is flash evaporated in a flash tank 7 to obtain flash oil gas and flash oil.

[0039] (b) Atmospheric flash + fractionation side column:

[0040] After the flash oil is heated in the vacuum tower feed heat exchanger 8, it enters the vacuum tower 9 for vacuum fractionation. The flash oil gas is connected to the vacuum pump outlet and enters the water cooler to be cooled to 50°C.

[0041] A vacuum pumping facility is installed on the top of the vacuum tower. The side oil of the vacuum tower enters the stripping tower and is stripped to a qualified flash point. After heat exchange and cooling, it is discharged from the device.

[0042] The top and middle circulation of the vacuum tower are set according to the heat of the whole tower.

[0043] According to a second aspect of the present invention, there is provided an application of any of the above-mentioned fractionation methods in low-oil separation.

[0044] The application of the fractionation method for reducing the vacuum fractionation load provided by the present invention is conducive to reducing the energy consumption and equipment requirements of the vacuum system, achieving the technical effect of reducing the gas phase load of the vacuum tower.

[0045] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0046] Example 1

[0047] A fractionation method for reducing vacuum fractionation load comprises the following steps:

[0048] In the fractionation process, the raw oil is first stripped and then flashed to obtain flash oil, which is then subjected to vacuum fractionation to reduce the vacuum fractionation load.

[0049] The method of stripping comprises the following steps:

[0050] The low-fraction oil after hydrogenation is passed into a stripping tower for stripping to remove light hydrocarbons and H2S components to obtain the stripping tower bottom oil.

[0051] The flash distillation method comprises the following steps:

[0052] The bottom oil of the stripping tower is passed into a normal pressure separation tank for flash evaporation at 1 barg to obtain flash gas and flash oil.

[0053] The method of vacuum fractionation comprises the following steps:

[0054] The flash oil is passed into a vacuum tower for vacuum fractionation.

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that the flash evaporation step is not performed;

[0057] The rest are the same as in Example 1.

[0058] Test example

[0059] A 300,000 tons / year lubricating oil hydrogenation unit uses straight-run diesel fraction as its raw material and produces super-high-temperature lubricating oil (280-340°C) and transformer lubricating oil (>340°C). The distillation process was originally designed as "stripping + vacuum fractionation" (i.e., the method of Comparative Example 1), but has now been adjusted to "stripping + flash distillation + vacuum fractionation" (i.e., the method of Example 1). A comparison of the technical indicators is shown in Tables 1 and 2.

[0060] Table 1 Technical performance and equipment comparison

[0061]

[0062] Table 2 Comparison of energy consumption and economy

[0063]

[0064] It can be seen that the present invention adopts the method of steam stripping + flash evaporation + decompression, which reduces the comprehensive energy consumption by 19.4%, saves nearly 6.2 tons of standard oil annually, has a significant energy-saving effect, reduces carbon emissions by 19.7 tons of CO2 annually, and reduces total carbon emissions by 19.4%. It is superior to traditional solutions in terms of energy saving and environmental protection.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fractionation method for reducing the vacuum fractionation load, characterized in that: The following steps are involved: In the fractionation process, the raw oil is first stripped and then flashed to obtain flash oil, which is then subjected to vacuum fractionation to reduce the vacuum fractionation load.

2. The fractionation method according to claim 1, wherein The raw oil includes low-fraction oil after hydrogenation.

3. The fractionation method according to claim 2, wherein The method of stripping comprises the following steps: The low-fraction oil after hydrogenation is passed into a stripping tower for stripping to remove light hydrocarbons and H2S components to obtain the stripping tower bottom oil.

4. The fractionation method according to claim 3, wherein The flash distillation method comprises the following steps: The bottom oil of the stripping tower is introduced into a normal pressure separation tank for flash evaporation at 1 barg to obtain flash gas and flash oil.

5. The fractionation method according to claim 4, characterized in that The method of the vacuum fractionation comprises the following steps: Passing the flash oil into a vacuum tower for vacuum fractionation; A vacuum pumping facility is provided on the top of the vacuum tower. The sideline oil of the vacuum tower enters the stripping tower and is stripped to a qualified flash point. After heat exchange and cooling, it exits the device.

6. Use of the fractionation method according to any one of claims 1 to 5 in low-oil separation.

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