Dry separation system and method for ionic liquid in alkylation reaction effluent

Abstract

The invention discloses a dry separation system and method for ionic liquid in alkylation reaction effluent, and relates to the field of petrochemical engineering, the alkylation reaction effluent firstly passes through a solid remover to remove suspended matters and then enters a flash tank, the ionic liquid content in the reaction effluent is concentrated through low-pressure flash evaporation, and the temperature of the reaction effluent is reduced; the cooled reaction effluent enters a low-temperature fine coalescer through a delivery pump to carry out low-temperature fine coalescence separation on the ionic liquid; and introducing the separated reaction effluent into an adsorption tank for deep adsorption. After the alkylation effluent is treated by the method, the ionic liquid content can be lower than 10mg / L, the removal rate of suspended matters reaches 99%, the traditional alkali washing and water washing process can be replaced, the whole system is in dry operation, the energy consumption and the ionic liquid consumption can be greatly reduced, the equipment corrosion is avoided, and the clean production of the alkylated oil is realized.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, specifically to a dry separation system and method for ionic liquids in alkylation reaction effluents. Background Technology

[0002] Alkylated oils, characterized by their absence of aromatics and olefins, low sulfur content, low vapor pressure, and high octane number, are an ideal component in blended gasoline. They are produced by the alkylation reaction of isobutane and butene in the presence of a catalyst. Currently, alkylation processes are mainly classified into liquid acid alkylation and solid acid alkylation processes based on catalyst type. Although solid acids are environmentally friendly, their industrial application is limited due to their susceptibility to coking and deactivation, requiring frequent regeneration. Liquid acid alkylation processes include hydrofluoric acid alkylation, sulfuric acid alkylation, and ionic liquid alkylation. Ionic liquids, as a novel compound system, possess characteristics such as a wide liquid temperature range, low vapor pressure, low volatility, good stability, high solubility, and adjustable acidity, making them highly promising for catalytic reactions.

[0003] With the commissioning of the 300,000-ton / year ionic liquid alkylation unit at Jiujiang Petrochemical, the consumption issues of the alkaline washing and water washing processes have become increasingly serious. For specific process details, please refer to... Figure 1 Furthermore, suspended solids in the process can clog and corrode the coalescer, affecting its separation efficiency and further increasing the consumption of alkaline washing and water washing. Chinese patent CN108795481A discloses a method for purifying and separating hydrocarbons and catalysts in the effluent of an alkylation reaction using an ionic liquid, employing a two-stage packed bed coalescer to separate the catalyst from the alkylation reaction effluent. Chinese patent CN110305691A discloses a short-process separation system for ionic liquids in alkylation reaction effluents, using a two-stage room-temperature coalescing separation combined with a one-stage low-temperature coalescing method to separate the ionic liquids from the alkylation effluent. While these patents can effectively remove ionic liquids from alkylation effluents, they cannot effectively remove suspended solids and dissolved acidic ionic liquids. Subsequent alkaline washing and water washing processes still require large amounts of alkaline water and demineralized water. Therefore, developing a dry separation method for ionic liquids in alkylation reaction effluents to replace alkaline washing and water washing processes is of great significance for energy conservation, emission reduction, and reduced consumption. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a dry separation system and method for ionic liquids in alkylation reaction effluents.

[0005] The technical solution of the present invention is as follows:

[0006] A dry separation system for ionic liquids in alkylation reaction effluents, comprising, in sequence, an ionic liquid alkylation reactor, a solids remover, a flash tank, a low-temperature fine coalescer, an adsorption tank, and a fractionation column.

[0007] The ionic liquid alkylation reactor is used for the ionic liquid-catalyzed reaction of isobutane and butene to obtain reaction effluent.

[0008] The solids remover is used to remove suspended solids from the reaction effluent;

[0009] The flash tank is used to remove alkanes from the reaction effluent;

[0010] The low-temperature fine coalescer is used to perform low-temperature fine coalescing separation of the reaction effluent from the flash tank;

[0011] The adsorption tank is used to adsorb and remove the reaction effluent from the low-temperature fine coalescer.

[0012] This invention also discloses a dry separation method for ionic liquids in alkylation reaction effluents. The reaction effluents from the ionic liquid alkylation reactor are first passed through a solids remover to remove suspended solids before entering a flash tank. The ionic liquid content in the reaction effluents is concentrated by low-pressure flash evaporation, and the temperature of the reaction effluents is reduced. The cooled reaction effluents are then fed into a low-temperature fine coalescer for low-fine coalescence separation of the ionic liquids. The separated reaction effluents are then fed into an adsorption tank for deep adsorption.

[0013] As a preferred embodiment of the present invention, the specific steps include:

[0014] S1: The reaction effluent from the ionic liquid alkylation reactor is fed into a solids remover to remove suspended solids from the reaction effluent;

[0015] S2: The reaction effluent obtained from S1 is fed into a flash tank to perform low-pressure flash evaporation on the isobutane in the reaction effluent, concentrate the ionic liquid in the reaction effluent, and control the temperature of the reaction effluent in the flash tank by adjusting the amount of isobutane vaporization.

[0016] S3: The reaction effluent obtained after S2 treatment is sent to a low-temperature fine coalescer to perform low-temperature fine coalescing separation of the ionic liquid in the reaction effluent;

[0017] S4: The reaction effluent obtained after S3 is passed into an adsorption tank to adsorb and remove the residual ionic liquid in the reaction effluent, resulting in an alkylation reaction effluent with an ionic liquid content of less than 10 mg / L.

[0018] As a preferred embodiment of the present invention, in step S1, the solid removal device is operated intermittently. After continuous operation for a certain period of time or when the pressure loss reaches 0.3 MPa, it is backwashed and regenerated by introducing isobutane or fresh water and nitrogen in reverse for 20-40 minutes.

[0019] In a preferred embodiment of the present invention, in step S1, the ionic liquid content in the reaction effluent is 50-300 ppm, the suspended solids content is 180-250 mg / L, and the ionic liquid density is 1000-1100 kg / m³. 3 The hydrocarbon phase is 700-750 kg / m³ 3 .

[0020] As a preferred embodiment of the present invention, in step S2, the temperature of the reaction effluent in the flash tank is 4.9-21.8℃, and the flash pressure is 0.07-0.2MPaG.

[0021] As a preferred embodiment of the present invention, in step S3, during the separation process of the low-temperature fine coalescer, the flow rate of the reaction effluent is 0.005-0.1 m / s, and the pressure drop is 0.02-0.1 MPa.

[0022] As a preferred embodiment of the present invention, in step S3, the low-temperature fine coalescer is provided with ionic liquid fibers.

[0023] As a preferred embodiment of the present invention, in step S4, the adsorption and removal are performed using activated carbon.

[0024] The beneficial effects of this invention are:

[0025] (1) The present invention utilizes the particle bed in the solids remover to perform deep filtration of suspended matter in the alkylation reaction effluent, which can effectively remove 99% of the suspended matter.

[0026] (2) The present invention uses low-temperature coalescence and adsorption to remove ionic liquids from the efflux of alkylation reaction, which has the characteristics of high separation accuracy and simple and flexible process. The content of ionic liquids in the hydrocarbon phase after separation is not higher than 10 mg / L.

[0027] (3) The present invention can reduce the consumption of soda ash and demineralized water in the existing alkylation alkaline washing and water washing processes of ionic liquids, reduce wastewater discharge, and reduce environmental pollution.

[0028] (4) The method adopted in this invention has the advantages of simple operation and high efficiency. The whole system operates in dry mode, which greatly reduces energy consumption and ionic liquid consumption, avoids equipment corrosion, and can save enterprises a lot of expenses and create considerable economic value. Attached Figure Description

[0029] Figure 1This is a flowchart of the existing alkylation effluent treatment process.

[0030] Figure 2 This is a schematic diagram of the dry separation method for ionic liquids in the efflux of the alkylation reaction of the present invention.

[0031] Figure 3 This is a schematic diagram of the dry separation system for ionic liquids in the alkylation reaction effluent of the present invention. Detailed Implementation

[0032] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0033] refer to Figure 2 and Figure 3 The present invention provides a dry separation system for ionic liquids in alkylation reaction effluents, which includes, in sequence: an ionic liquid alkylation reactor 100, a solids remover 200, a flash tank 300, a low-temperature fine coalescer 400, an adsorption tank 500, and a fractionation tower 600.

[0034] The ionic liquid alkylation reactor 100 is used for the ionic liquid-catalyzed reaction of isobutane and butene to obtain reaction effluent.

[0035] The solids remover 200 is used to remove suspended solids from the reaction effluent;

[0036] The flash tank 300 is used to remove alkanes from the reaction effluent;

[0037] The low-temperature fine coalescer 400 is used to perform low-temperature fine coalescing separation of the reaction effluent from the flash tank.

[0038] The adsorption tank 500 is used to adsorb and remove the reaction effluent from the low-temperature fine coalescer 400.

[0039] The fractionation tower 600 is used to fractionate the reaction effluent after adsorption and removal.

[0040] By using a particle bed in a solids remover to perform deep filtration of suspended solids in the alkylation reaction effluent, 99% of the suspended solids can be effectively removed.

[0041] The present invention also provides a dry separation method for ionic liquids in alkylation reaction effluents, the method comprising: solid removal, flash evaporation, low-temperature fine coalescence and deep adsorption;

[0042] In this embodiment, after the alkylation reaction effluent is deionized by existing physical methods, it is first passed into a solids remover 200 to remove suspended solids, and then enters a flash tank 300 to concentrate the ionic liquid content in the reaction effluent through low-pressure flash evaporation and reduce the temperature of the reaction effluent. The cooled reaction effluent is then pumped into a low-temperature fine coalescer 400 for low-temperature fine coalescing separation of the ionic liquid. The separated reaction effluent is then passed into an adsorption tank 500 for deep adsorption to obtain alkylated oil with an ionic liquid content of less than 10 mg / L.

[0043] Specifically, the solid removal device operates intermittently. After continuous operation for a certain period of time or when the pressure loss reaches 0.3 MPa, it is regenerated by backflushing with isobutane or fresh water and nitrogen for 20-40 minutes.

[0044] Specifically, the ionic liquid content in the reaction effluent is 50-300 ppm, the suspended solids content is 180-250 mg / L, and the ionic liquid density is 1000-1100 kg / m³. 3 The hydrocarbon phase is 700-750 kg / m³ 3 ;

[0045] Specifically, the temperature of the reaction effluent in the flash tank is 4.9-21.8℃, and the flash pressure is 0.07-0.2 MPaG;

[0046] Specifically, during the separation process in the low-temperature fine coalescer, the flow rate of the reaction effluent is 0.005-0.1 m / s, and the pressure drop is 0.02-0.1 MPa.

[0047] Specifically, the low-temperature fine coalescer described in the following embodiments is equipped with ionic liquid fibers.

[0048] Specifically, in the following embodiments, the adsorption and removal are performed using activated carbon.

[0049] The ionic liquid alkylation unit at Jiangxi Petrochemical Plant uses a composite ionic liquid to catalyze the reaction of isobutane (C4) and butene to produce high-octane alkylated oil. The ionic liquid entrainment in the alkylation reaction effluent before alkaline washing and water washing is approximately 50-300 ppm, the suspended solids content is approximately 200 mg / L, and the ionic liquid density is 1042 kg / m³. 3 The hydrocarbon phase is 715 kg / m³ 3 .

[0050] Example 1

[0051] according to Figure 2 The dry separation method for ionic liquids in the alkylation reaction effluent, as shown, removes suspended solids and ionic liquids from the alkylation reaction effluent. The specific process is as follows:

[0052] Step 1: The alkylation reaction effluent with an ionic liquid entrainment of approximately 50 ppm and a suspended solids content of approximately 200 mg / L is fed into a solids remover to remove 99% of the suspended solids from the effluent.

[0053] Step 2: The effluent with suspended solids removed is passed into a flash tank, and the isobutane in the effluent is flashed at a low pressure of 0.07 MPaG to obtain a reaction effluent at a temperature of 4.9℃.

[0054] Step 3: The alkylation reaction effluent after flash evaporation and cooling is sent to a low-temperature fine coalescer by a transfer pump to perform low-temperature fine coalescing and separation of ionic liquids in the reaction effluent.

[0055] Step 4: The alkylation reaction effluent obtained by low-temperature fine polymerization is passed into an adsorption tank to adsorb and remove the residual ionic liquid in the effluent, resulting in an alkylation reaction effluent with an ionic liquid content of 8.1 mg / L.

[0056] Example 2

[0057] according to Figure 2 The dry separation method for ionic liquids in the alkylation reaction effluent, as shown, removes suspended solids and ionic liquids from the alkylation reaction effluent. The specific process is as follows:

[0058] Step 1: The alkylation reaction effluent with an ionic liquid entrainment of approximately 150 ppm and a suspended solids content of approximately 200 mg / L is fed into a solids remover to remove 99% of the suspended solids from the effluent.

[0059] Step 2: The effluent with suspended solids removed is passed into a flash tank, and the isobutane in the effluent is flashed at a low pressure of 0.1 MPaG to obtain a reaction effluent at a temperature of 11.8℃.

[0060] Step 3: The alkylation reaction effluent after flash evaporation and cooling is sent to a low-temperature fine coalescer by a transfer pump to perform low-temperature fine coalescing and separation of ionic liquids in the reaction effluent.

[0061] Step 4: The alkylation reaction effluent obtained by low-temperature fine polymerization is passed into an adsorption tank to adsorb and remove the residual ionic liquid in the effluent, resulting in an alkylation reaction effluent with an ionic liquid content of 8.5 mg / L.

[0062] Example 3

[0063] according to Figure 2 The dry separation method for ionic liquids in the alkylation reaction effluent, as shown, removes suspended solids and ionic liquids from the alkylation reaction effluent. The specific process is as follows:

[0064] Step 1: The alkylation reaction effluent with an ionic liquid entrainment of approximately 300 ppm and a suspended solids content of approximately 200 mg / L is fed into a solids remover to remove 99% of the suspended solids from the effluent.

[0065] Step 2: The effluent with suspended solids removed is passed into a flash tank, and the isobutane in the effluent is flashed at a low pressure of 0.2 MPaG to obtain a reaction effluent at a temperature of 21.8℃.

[0066] Step 3: The alkylation reaction effluent after flash evaporation and cooling is sent to a low-temperature fine coalescer by a transfer pump to perform low-temperature fine coalescing and separation of ionic liquids in the reaction effluent.

[0067] Step 4: The alkylation reaction effluent obtained by low-temperature fine polymerization is passed into an adsorption tank to adsorb and remove the residual ionic liquid in the effluent, resulting in an alkylation reaction effluent with an ionic liquid content of 7.6 mg / L.

[0068] In Examples 1-3, the concentration of Al ions in the samples was detected by an inductively coupled plasma (ICP) analyzer, and the content of ionic liquid in the alkylation reaction effluent was calculated. The content of suspended solids in the alkylation reaction effluent was determined by a turbidimeter.

[0069] Using the method and apparatus of this invention, the ionic liquid content in the separated alkylation reaction effluent is no greater than 10 mg / L, and the suspended solids removal rate can reach 99%, meeting the requirements of the production process. Furthermore, compared with the existing processes mentioned in the background art, [reference to...] Figure 1 It can reduce the consumption of soda ash and demineralized water in existing ionic liquid alkylation alkaline washing and water washing processes, reduce wastewater discharge, and greatly reduce environmental pollution.

[0070] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A dry separation system for ionic liquids in alkylation reaction effluents, characterized in that, The components include, in sequence, an ionic liquid alkylation reactor (100), a solids remover (200), a flash tank (300), a low-temperature fine coalescer (400), an adsorption tank (500), and a fractionation tower (600). The ionic liquid alkylation reactor (100) is used for the ionic liquid-catalyzed reaction of isobutane and butene to obtain the reaction effluent; The solids remover (200) is used to remove suspended solids from the reaction effluent; The flash tank (300) is used to remove alkanes from the reaction effluent; The low-temperature fine coalescer (400) is used to perform low-temperature fine coalescing separation of the reaction effluent from the flash tank; The adsorption tank (500) is used to adsorb and remove the reaction effluent from the low-temperature fine coalescer (400).

2. A dry separation method for ionic liquids in alkylation reaction effluents, characterized in that, The effluent from the ionic liquid alkylation reactor (100) is first passed through a solids remover (200) to remove suspended solids before entering a flash tank (300). The ionic liquid content in the effluent is concentrated by low-pressure flash evaporation, and the temperature of the effluent is reduced. The cooled effluent enters a low-temperature fine coalescer (400) for low-fine coalescing separation of the ionic liquid. The separated effluent is then passed into an adsorption tank (500) for deep adsorption.

3. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 2, characterized in that, Includes the following steps: S1: The reaction effluent from the ionic liquid alkylation reactor (100) is fed into the solids remover (200) to remove suspended solids from the reaction effluent; S2: The reaction effluent obtained from S1 is fed into a flash tank (300) to perform low-pressure flash evaporation on the isobutane in the reaction effluent, concentrate the ionic liquid in the reaction effluent, and control the temperature of the reaction effluent in the flash tank (300) by adjusting the amount of isobutane vaporization. S3: The reaction effluent obtained after S2 treatment is sent into a low-temperature fine coalescer (400) to perform low-temperature fine coalescing separation of the ionic liquid in the reaction effluent; S4: The reaction effluent obtained after S3 is passed into an adsorption tank to adsorb and remove the residual ionic liquid in the reaction effluent, resulting in an alkylation reaction effluent with an ionic liquid content of less than 10 mg / L.

4. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 3, characterized in that, In step S1, the solid removal device operates intermittently. After continuous operation for a certain period of time or when the pressure loss reaches 0.3 MPa, it is backwashed and regenerated by introducing isobutane or fresh water and nitrogen in reverse. The backwashing time is 20-40 minutes.

5. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 3, characterized in that, In step S1, the ionic liquid content in the reaction effluent is 50-300 ppm, the suspended solids content is 180-250 mg / L, and the ionic liquid density is 1000-1100 kg / m³. 3 The hydrocarbon phase is 700-750 kg / m³ 3 .

6. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 3, characterized in that, In step S2, the temperature of the reaction effluent in the flash tank is 4.9-21.8℃, and the flash pressure is 0.07-0.2MPaG.

7. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 3, characterized in that, In step S3, during the low-temperature fine coalescing separation process, the flow rate of the reaction effluent is 0.005-0.1 m / s, and the pressure drop is 0.02-0.1 MPa.

8. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 3, characterized in that, In step S3, the low-temperature fine coalescer is provided with ionic liquid fibers.

9. The dry separation method for ionic liquids in alkylation reaction effluents according to claim 3, characterized in that, In step S4, the adsorption and removal are performed using activated carbon.

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