An alkaline washing demulsification method and alkaline washing demulsification system for high carbon number fischer-tropsch oil

Abstract

The application discloses an alkali washing demulsification method and system for high-carbon Fischer-Tropsch oil, wherein the alkali washing demulsification method specifically comprises the following steps: 1) mixing the high-carbon Fischer-Tropsch oil with an alkali washing liquid and a demulsifier, and then performing deacidification and demulsification treatment; 2) washing the upper oil phase after alkali washing and demulsification; 3) adding acid into the lower water phase after demulsification and the water phase after washing to perform neutralization reaction; 4) evaporating and desalting the water phase after neutralization; and 5) performing vacuum rectification on the demulsifier to recycle the demulsifier, and recycling the water. After the alkali washing demulsification treatment of the high-carbon Fischer-Tropsch oil by the demulsification method, the oil yield is effectively improved, and the acidity of the oil after alkali washing and water washing is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of demulsification, specifically relating to an alkaline washing demulsification method and system for high carbon number Fischer-Tropsch oil. Background Technology

[0002] Fischer-Tropsch oil typically exhibits high acid values, directly impacting the production of downstream fine chemical products and related equipment, necessitating deacidification treatment. Current deacidification processes for Fischer-Tropsch oil typically involve alkaline washing followed by water washing. The sodium hydroxide solution added during alkaline washing reacts with the long-chain acids in the high-carbon Fischer-Tropsch oil to form long-chain alkanoates, which are the primary cause of emulsion formation. Furthermore, the long-chain alkanoates act as surfactants, adsorbing at the oil-water interface and preventing the aggregation of water or oil droplets, thus reducing the recovery rate of high-carbon Fischer-Tropsch oil after alkaline washing. Simultaneously, the formation of the oil-water emulsion leads to incomplete reaction between the acids and alkali in the high-carbon Fischer-Tropsch oil, resulting in a high acid value in the Fischer-Tropsch oil after alkaline washing and water washing. Therefore, developing a novel demulsification method that can improve the oil yield after alkaline washing of high-carbon Fischer-Tropsch oil, reduce its acid value after alkaline washing and water washing, and simultaneously reduce the discharge of oily wastewater remains a key research focus. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide an alkaline washing demulsification method for high carbon number Fischer-Tropsch oil, which solves the problems of low oil yield and high acid value caused by emulsification after alkaline washing of high carbon number Fischer-Tropsch oil.

[0004] Another objective of this invention is to provide an alkaline washing and demulsification system for high carbon number Fischer-Tropsch oil.

[0005] To solve the above problems, the technical solution adopted by the present invention is: an alkaline washing demulsification method for high carbon number Fischer-Tropsch oil, which specifically includes the following steps:

[0006] S1. High carbon number Fischer-Tropsch oil, alkaline washing solution and demulsifier are mixed and then subjected to deacidification and demulsification treatment to obtain high carbon number Fischer-Tropsch oil separation liquid after alkaline washing and demulsification.

[0007] S2. Separate the upper oil phase of the high carbon number Fischer-Tropsch oil separation liquid after demulsification, and wash the upper oil phase with water to obtain the washed oil phase.

[0008] S3. Add acid to the lower aqueous phase of the high carbon number Fischer-Tropsch oil separation liquid after demulsification and the aqueous phase after water washing in S2 to carry out a neutralization reaction to obtain a neutralized aqueous phase.

[0009] S4. The neutralized aqueous phase is evaporated and desalted, and the demulsifier and water are distilled under reduced pressure. The water and demulsifier are recycled.

[0010] Preferably, in S1, the high-carbon Fischer-Tropsch oil is a C10 to C20 high-carbon Fischer-Tropsch synthetic oil.

[0011] Preferably, in step S1, the alkaline washing solution is a 0.5-1.5% wt sodium hydroxide solution.

[0012] Preferably, in step S1, the volume ratio of the high-carbon Fischer-Tropsch oil to the alkaline washing solution is 3 to 10.

[0013] Preferably, in step S1, the temperature for deacidification and demulsification is 20–50°C, and the time for deacidification and demulsification is 20–50 min.

[0014] Preferably, in step S1, the demulsifier is a sulfoxide and / or a sulfone extractant, including one of dimethyl sulfoxide, sulfolane, dimethyl sulfone, and diethyl sulfone.

[0015] Preferably, in step S1, the high carbon number Fischer-Tropsch oil separation liquid after alkaline washing and demulsification is mixed with the demulsifier at an oil-to-agent ratio of 10 to 50.

[0016] Preferably, in step S1, the stirring time during deacidification and demulsification is 10-50 min; and the temperature during deacidification and demulsification is 30-50°C.

[0017] Preferably, in step S2, the settling time is 0.3 to 2 hours.

[0018] The second technical solution of the present invention is implemented as follows: an alkaline washing and demulsification system for high carbon number Fischer-Tropsch oil, comprising an alkaline washing and demulsification device, a first liquid separator, a second liquid separator, a water washing device, and a neutralization device, wherein the alkaline washing and demulsification device is connected to the first liquid separator, the water washing device and the neutralization device are both connected to the first liquid separator, the inlet of the second liquid separator is connected to the water washing device, and the outlet of the second liquid separator is connected to the neutralization device.

[0019] Preferably, the demulsification system further includes an evaporation device and a distillation device, and the neutralization device is connected to the distillation device through the evaporation device.

[0020] Preferably, the demulsification system further includes an acid storage device, which is connected to the neutralization device.

[0021] Preferably, the demulsification system further includes a raw material auxiliary agent storage device, which is connected to the alkaline washing demulsification device.

[0022] Preferably, the raw material and auxiliary agent storage device includes a Fischer-Tropsch oil storage device, an acid storage device, and a demulsifier storage device, all of which are connected to the alkaline washing and demulsification device.

[0023] Compared with existing technologies, the demulsification method of this invention for high-carbon Fischer-Tropsch oil not only effectively improves the oil yield to over 99%, but also effectively reduces the acidity of the oil after water washing, with the acidity reaching as low as 0 mg KOH / 100 mL. In addition, the demulsification method is simple and easy to operate, and is worthy of widespread promotion and application. Attached Figure Description

[0024] Figure 1 A process flow diagram of the demulsification system for high carbon number Fischer-Tropsch oil provided in an embodiment of the present invention.

[0025] In the diagram, 1. Alkali washing demulsifier, 2. First separation device, 3. Second separation device, 4. Water washing device, 5. Neutralization device, 6. Evaporation device, 61. Evaporator, 62. Brine storage device, 7. Distillation device, 71. Distillation column, 72. Water storage tank, 8. Acid storage device, 9. Raw material and auxiliary agent storage device, 91. Acid storage device, 92. Acid storage device, 93. Demulsifier storage device. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] In the description of this invention, it should be clarified that the terms "vertical," "lateral," "longitudinal," "front," "rear," "left," "right," "up," "down," and "horizontal," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are merely for the convenience of describing this invention. They do not imply that the device or element referred to must have a specific orientation or position, and therefore should not be construed as a limitation of this invention. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," and "joined" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] This invention provides an alkaline washing demulsification method for high carbon number Fischer-Tropsch oil, which specifically includes the following steps:

[0029] S1. High carbon number Fischer-Tropsch oil, alkaline washing solution and demulsifier are mixed and then subjected to deacidification and demulsification treatment to obtain high carbon number Fischer-Tropsch oil separation liquid after alkaline washing and demulsification.

[0030] S2. Separate the upper oil phase of the high carbon number Fischer-Tropsch oil separation liquid after demulsification, and wash the upper oil phase with water to obtain the washed oil phase.

[0031] S3. Add acid to the lower aqueous phase of the high carbon number Fischer-Tropsch oil separation liquid after demulsification and the aqueous phase after water washing in S2 to carry out a neutralization reaction to obtain a neutralized aqueous phase.

[0032] S4. The neutralized aqueous phase is evaporated and desalted, and the demulsifier and water are distilled under reduced pressure. The water and demulsifier are recycled.

[0033] Further, in step S1, the high-carbon Fischer-Tropsch oil is a C10-C20 high-carbon Fischer-Tropsch synthetic oil; in step S1, the alkaline washing solution is a 0.5-1.5% wt sodium hydroxide solution; in step S1, the volume ratio of the high-carbon Fischer-Tropsch oil to the alkaline washing solution is 3-10; in step S1, the deacidification and demulsification temperature is 20-50°C, and the deacidification and demulsification time is 20-50 min; in step S1, the demulsifier is a sulfoxide and / or a sulfone extractant, including one of dimethyl sulfoxide, sulfolane, dimethyl sulfone, and diethyl sulfone; in step S1, the high-carbon Fischer-Tropsch oil separation liquid after alkaline washing and demulsification and the demulsifier are in an oil-to-agent ratio of 10-50; in step S1, the stirring time during deacidification and demulsification is 10-50 min; the deacidification and demulsification temperature is 30-50°C; and the settling time is 0.3-2 h, preferably 0.5 h.

[0034] After adopting the above scheme, the demulsification treatment of high-carbon Fischer-Tropsch oil by using the demulsification method of the present invention not only effectively improves the oil yield, but also effectively reduces the acidity of the oil after water washing.

[0035] This invention also provides an alkaline washing and demulsification system for high carbon number Fischer-Tropsch oil, including an alkaline washing and demulsification device 1, a first liquid separator 2, a second liquid separator 3, a water washing device 4, and a neutralization device 5. The alkaline washing and demulsification device 1 is connected to the first liquid separator 2, the water washing device 4 and the neutralization device 5 are both connected to the first liquid separator 2, the inlet of the second liquid separator 3 is connected to the water washing device 4, and the outlet of the second liquid separator 3 is connected to the neutralization device 5.

[0036] Furthermore, the demulsification system also includes an evaporation device 6 and a distillation device 7, with the neutralization device 5 connected to the distillation device 7 via the evaporation device 6.

[0037] Furthermore, the evaporation device 6 includes an evaporator 61 and a brine storage device 62, with the evaporator 61 connected to the brine storage device 62; by setting up the brine storage device 62, the purpose of facilitating the collection of brine during the evaporation process is effectively achieved.

[0038] Furthermore, the distillation apparatus 7 includes a distillation column 71 and a water storage tank 72. The distillation column 71 is connected to the water storage tank 72, the water storage tank 72 is connected to the water washing device 4, and the evaporation device 6 is connected to the distillation column 71. By setting up the water storage tank 72 and connecting it to the water washing device 4, not only is the purpose of collecting water during the distillation process achieved, but it is also convenient to add the recovered water back into the water washing device 4, thereby achieving the effects of recycling and energy conservation and environmental protection.

[0039] Furthermore, the distillation column 71 is also connected to the demulsifier storage device 93; by connecting the distillation column 71 to the demulsifier storage device 93, the purpose of recycling the demulsifier is effectively achieved.

[0040] Furthermore, the demulsification system also includes an acid storage device 8, which is connected to the neutralization device 5.

[0041] Furthermore, the demulsification system also includes a raw material auxiliary agent storage device 9, which is connected to the alkaline washing demulsification device 1.

[0042] Furthermore, the raw material and auxiliary agent storage device 9 includes a Fischer-Tropsch oil storage device 91, an acid storage device 92, and a demulsifier storage device 93. The Fischer-Tropsch oil storage device 91, the acid storage device 92, and the demulsifier storage device 93 are all connected to the alkaline washing and demulsification device 1. By setting up the Fischer-Tropsch oil storage device 91, the acid storage device 92, and the demulsifier storage device 93, and connecting the Fischer-Tropsch oil storage device 91, the acid storage device 92, and the demulsifier storage device 93 to the alkaline washing and demulsification device 1, it is convenient to automatically add alkaline washing, raw materials, and demulsifiers to the alkaline washing and demulsification device 1.

[0043] Furthermore, the second liquid separation component 3 is a liquid separation tank, and the water outlet of the liquid separation tank is connected to the pipeline between the first liquid separation component 2 and the neutralization device 5; by connecting the water outlet of the liquid separation tank to the pipeline between the first liquid separation component 2 and the neutralization device 5, the purpose of water reuse is effectively achieved.

[0044] The following are specific embodiments.

[0045] Example 1

[0046] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 20 with dimethyl sulfoxide at 30 °C for 30 min to deacidify and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 0.5 h. After water washing of the upper oil phase, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.6%.

[0047] Example 2

[0048] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 20 with dimethyl sulfoxide at 40 °C for 30 min to deacidify and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 0.5 h. After washing the upper oil phase with water, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.4%.

[0049] Example 3

[0050] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 20 with dimethyl sulfoxide at 50 °C for 30 min to deacidify and demulsify. After alkaline washing and demulsification, the mixture was allowed to stand for 0.5 h. After washing the upper oil phase with water, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.5%.

[0051] Example 4

[0052] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 10 with dimethyl sulfoxide at 30 °C for 30 min to deacidify and demulsify. After alkaline washing and demulsification, the mixture was allowed to stand for 0.5 h. After washing the upper oil phase with water, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.6%.

[0053] Example 5

[0054] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 30 and a volume ratio of 5 to 30 with dimethyl sulfoxide. The mixture was stirred at 30 °C for 30 min to remove acid and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 0.5 h. After washing the upper oil phase with water, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.1%.

[0055] Example 6

[0056] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 30 and a volume ratio of 5 to 30 with dimethyl sulfoxide. The mixture was stirred at 30 °C for 30 min to remove acid and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 0.3 h. After washing the upper oil phase with water, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.0%.

[0057] Example 7

[0058] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 30 and a volume ratio of 5 to 30 with dimethyl sulfoxide. The mixture was stirred at 30 °C for 30 min to remove acid and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 0.7 h. After washing the upper oil phase with water, the acidity was 0 mg KOH / 100 mL, and the oil yield was 99.5%.

[0059] Example 8

[0060] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 30 and a volume ratio of 5 to 30 to dimethyl sulfoxide. The mixture was stirred at 30 °C for 30 min to remove acid and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 1 h. The oil yield was 99.6%.

[0061] Comparison Column 1

[0062] High-carbon Fischer-Tropsch oil feedstock (acidity 280 mg KOH / 100 mL) was mixed with 1% wt sodium hydroxide solution at a volume ratio of 5 to 30 with dimethyl sulfoxide at 20 °C for 30 min to deacidify and break emulsion. After alkaline washing and demulsification, the mixture was allowed to stand for 0.5 h. After water washing of the upper oil phase, the acidity was 89 mg KOH / 100 mL, and the oil yield was 33.6%.

[0063] Comparison Column 2

[0064] High-carbon Fischer-Tropsch oil feedstock was mixed with 1% wt sodium hydroxide solution at a volume-to-oil ratio of 5 at 30°C and stirred for 30 min to remove acid. After washing with water, the acidity was 123 mg KOH / 100 mL, and the oil yield was 22.4%.

[0065] By comparing the oil yield and acidity value after water washing of Examples 1-11 and Comparative Examples 1-2, it can be seen that by using the demulsification method of the present invention to demulsify high-carbon Fischer-Tropsch oil, not only is the oil yield effectively improved, reaching over 99%, but the acidity after water washing is also effectively reduced, with the lowest acidity reaching 0 mg KOH / 100 mL.

[0066] In summary, by using the demulsification method of this invention to perform alkaline washing and demulsification treatment on high-carbon Fischer-Tropsch oil, not only is the oil yield effectively improved, but the acidity of the oil after water washing is also effectively reduced.

[0067] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for alkaline washing and demulsification of high carbon number Fischer-Tropsch oil, characterized in that, The method specifically includes the following steps: S1. High carbon number Fischer-Tropsch oil (C10-C20), alkaline washing solution, and demulsifier are mixed and stirred at 30-50°C to perform deacidification and demulsification treatment, thereby obtaining high carbon number Fischer-Tropsch oil separation liquid after alkaline washing and demulsification; the demulsifier is sulfoxide and / or sulfone, including one of dimethyl sulfoxide, sulfolane, dimethyl sulfone, and diethyl sulfone. S2. Separate the upper oil phase of the high carbon number Fischer-Tropsch oil separation liquid after demulsification, and wash the upper oil phase with water to obtain the washed oil phase. S3. Add acid to the lower aqueous phase of the high carbon number Fischer-Tropsch oil separation liquid after demulsification and the aqueous phase after water washing in S2 to carry out a neutralization reaction to obtain a neutralized aqueous phase. S4. The neutralized aqueous phase is evaporated and desalted, and the demulsifier and water are distilled under reduced pressure. The water and demulsifier are recycled.

2. The alkaline washing and demulsification method for high carbon number Fischer-Tropsch oil according to claim 1, characterized in that, In step S1, the alkaline washing solution is a 0.5~1.5wt% sodium hydroxide solution.

3. The alkaline washing and demulsification method for high-carbon-number Fischer-Tropsch oil according to claim 2, characterized in that, In step S1, the volume ratio of the high-carbon Fischer-Tropsch oil to the alkaline washing solution is 3 to 10.

4. The alkaline washing and demulsification method for high carbon number Fischer-Tropsch oil according to claim 3, characterized in that, In step S1, the deacidification and demulsification time is 20-50 minutes.

5. The alkaline washing demulsification method for high carbon number Fischer-Tropsch oil according to claim 4, characterized in that, In S1, the high carbon number Fischer-Tropsch oil and the demulsifier are in an oil-to-demulsifier ratio of 10 to 50.

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