CN115746902A

CN115746902A - Method and device for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil product

Info

Publication number: CN115746902A
Application number: CN202211251533.8A
Authority: CN
Inventors: 龙爱斌; 耿春宇; 陈彪; 师海峰; 赵玲玉; 秦如梦; 董根全; 高琳; 杨勇; 李永旺
Original assignee: Synfuels China Inner Mongolia Co ltd; Zhongke Synthetic Oil Technology Co Ltd
Current assignee: Synfuels China Inner Mongolia Co ltd; Zhongke Synthetic Oil Technology Co Ltd
Priority date: 2022-10-13
Filing date: 2022-10-13
Publication date: 2023-03-07

Abstract

The invention provides a method for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil products and a device for implementing the method. The method comprises the steps of carrying out extraction separation, water washing, adsorption separation, oil-water separation, rectification and other treatments on the Fischer-Tropsch synthesis oil product, so as to remove the oxygen-containing compounds, and further realize the advantages of high removal rate of the oxygen-containing compounds, high recovery rate of hydrocarbons and the like.

Description

Method and device for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil product

Technical Field

The invention belongs to the field of Fischer-Tropsch oil product processing, and relates to a method for removing oxygen-containing compounds from Fischer-Tropsch synthesis oil products and a device for implementing the method.

Background

The Fischer-Tropsch synthesis is a process for converting synthesis gas (carbon monoxide and hydrogen) from natural gas, coal and the like into synthetic hydrocarbon fuels and chemicals with chain lengths from C1 to more than C100 through a catalyst, and has extremely important significance for meeting the increasing energy requirements of China.

The Fischer-Tropsch synthesis reaction oil product contains a large amount of normal alkane and olefin, and also contains oxygen-containing compounds such as alcohol, ketone, acid, ester and the like, and the content is generally about 5wt% to 15wt%. The existence of organic acid in the Fischer-Tropsch synthetic oil seriously corrodes equipment, is not beneficial to the further processing of the synthetic oil and has larger influence on the subsequent process; other oxygen-containing organic matters such as alcohol, aldehyde, ketone and the like can generate complexation or substitution reaction with the Lewis acid catalyst, so that part of the catalyst is poisoned and inactivated, and downstream production is influenced; the presence of oxygenates can also have varying degrees of impact on the odor, color of the product, oxidation stability of the lubricant base oil, and other properties. Therefore, the removal of the oxygen-containing compounds has very important significance for improving the economic benefit and the product quality of subsequent products. At present, the method for removing the oxygen-containing compounds in Fischer-Tropsch oil products at home and abroad mainly comprises an extraction method, a rectification method, an adsorption method, a hydrogenation method, a chemical method and the like.

Patent CN100575320C describes a process for removing oxygenates from the condensate product of the fractionation of a hydrocarbon stream of a low temperature cobalt based fischer-tropsch reaction using a mixture of methanol and water as solvent. The method comprises three main devices, namely a liquid-liquid extraction tower, an extractant recovery tower and a stripping tower, can recover less than 92 percent of olefin and paraffin, and the content of oxygen-containing substances is less than 0.2 weight percent, but the method has lower recovery rate of the olefin and the paraffin, so that the method has insufficient economy.

The patent application CN112126461A introduces a process for removing oxygen-containing compounds in Fischer-Tropsch oil products by combining reaction, extraction and adsorption, and specifically relates to a process for removing water phase by alkaline aqueous solution alkaline washing Fischer-Tropsch oil products and hydrosulfite aqueous solution reaction, and removing alcohol by using ethylene glycol or polyethylene glycol. The process can remove the oxygen-containing compounds to below 1 ppm. The method removes the oxygen-containing compound by introducing a method of reacting inorganic salt with the oxygen-containing compound, but can cause the problems of controlling reaction balance, introducing new impurities into Fischer-Tropsch oil products and treating waste liquid.

Patent CN105777467B introduces a method for separating oxygen-containing compounds and 1-hexene from fischer-tropsch synthesis oil, specifically, an extracting agent is used to remove oxygen-containing compounds in C6 hydrocarbon stream, and then tertiary olefins are converted into corresponding ethers and removed under the action of a methanol etherification catalyst. Wherein, in the process of removing the oxygen-containing compound, three extracting agents of water, an aqueous solution of the oxygen-containing compound and 1-methyl-2-pyrrolidone are respectively adopted. 1-methyl-2-pyrrolidone has a high boiling point and is completely mixed with almost all solvents, thus causing problems in recovery of the extractant and product purity.

Patent application CN113862023A introduces a method and a device for removing oxygen-containing compounds from Fischer-Tropsch oil, and specifically relates to a method for obtaining an extract phase and a raffinate phase by countercurrent extraction of Fischer-Tropsch oil with an extraction solvent, and then obtaining Fischer-Tropsch oil with oxygen-containing compounds removed by a method for washing the raffinate phase with water. However, the oxygenate content of the Fischer-Tropsch oil can only be reduced to about 1000ppm, with only about 92% oil recovery.

Therefore, there is still a need to develop a method for removing oxygenates different from the prior art, which can satisfy the requirements of removing oxygenates efficiently, recovering hydrocarbons with high yield and avoiding the introduction of new impurities.

Disclosure of Invention

Aiming at the defects in the prior art, the inventor provides a method for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil products through research, the method comprises the steps of extraction separation, water washing, adsorption separation, oil-water separation, rectification and the like, and the method has the advantages of convenience in operation, high removal rate of the oxygen-containing compounds, high recovery rate of hydrocarbons and the like. After the method is used for removing the oxygen-containing compounds, the purity of the hydrocarbons reaches over 99.9wt%, and the yield of the hydrocarbons reaches over 98 wt%.

In one aspect, the invention relates to a method for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil products, which comprises the following steps:

(1) Extracting and separating Fischer-Tropsch synthesis oil products, dissolving oxygen-containing compounds in the Fischer-Tropsch synthesis oil products by using an extracting agent to obtain an extract phase and a raffinate phase, wherein the extracting agent is a mixture of at least one of desalted water and Fischer-Tropsch synthesis water and a solvent selected from the following solvents: methanol, ethanol, ethylene glycol, sulfolane, NMP, DMF, or any combination thereof;

(2) Washing the raffinate phase obtained in the step (1) with water to further remove oxygen-containing compounds and obtain a Fischer-Tropsch synthesis oil phase and a washing water phase;

(3) Adsorbing and separating the Fischer-Tropsch synthesis oil phase obtained in the step (2) to obtain an adsorbed and separated Fischer-Tropsch synthesis oil product;

(4) Carrying out oil-water separation on the extraction phase obtained in the step (1) and the washing water phase obtained in the step (2) to obtain an oil phase and a water phase, and returning the oil phase to the step (1) for extraction and separation;

(5) And (3) rectifying the water phase obtained in the step (4) to obtain a solvent component and an oxygen-containing compound aqueous solution in the extracting agent, returning the solvent component to the step (1) for reuse, and treating the oxygen-containing compound aqueous solution by sewage.

In another aspect, the invention relates to an apparatus for carrying out the above method, wherein the apparatus comprises: the device comprises an extraction separation unit, a water washing unit, an adsorption unit, an oil-water separation unit and a rectification unit which are sequentially connected in a fluid communication mode.

The exemplary aspects of the present invention may achieve the following advantages and other advantages or advantages:

1. the removal rate of the oxygen-containing compounds is high, and pure hydrocarbon products (the purity is more than or equal to 99.9 wt%) can be obtained.

2. The hydrocarbon recovery rate is high (more than or equal to 98wt percent), and the economic benefit is remarkable.

3. The deep removal method of the oxygen-containing compounds in the Fischer-Tropsch synthesis oil product provided by the invention is low in energy consumption, simple and easy for industrial application.

4. The method for deeply removing the oxygen-containing compounds in the Fischer-Tropsch synthesis oil adopts an extraction separation mode which can be centrifugal extractor extraction or extraction separation of an extraction tower, and can more effectively improve the separation efficiency of extraction separation.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a schematic diagram of an exemplary Fischer-Tropsch oil oxygenate removal scheme.

Wherein, 1 is an extraction separation unit; 2 is a water washing unit; 3 is an adsorption unit; 4 is an oil-water separation unit; 5 is a rectification unit; 101 is a Fischer-Tropsch synthesis oil product; 102 is a fresh extractant; 103, extracting a raffinate phase; 104 is desalted water; 105 is a washing water phase; 106 is Fischer-Tropsch synthetic oil phase; 107 is the Fischer-Tropsch synthesis oil (with oxygen-containing compounds removed) after adsorption and separation; 108 is an extraction phase; 109 is an oil phase after oil-water separation; 110 is water phase after oil-water separation; 111 is a solvent component in the extractant which is recycled; 112 is an aqueous oxygenate solution.

Detailed Description

The following describes in detail specific embodiments of the present invention. The specific embodiments described herein are merely illustrative and explanatory of the invention and are not restrictive thereof.

In one embodiment, the invention provides a method for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil products, which comprises the following steps:

(3) Carrying out adsorption separation on the Fischer-Tropsch synthesis oil phase obtained in the step (2) to obtain an adsorption-separated Fischer-Tropsch synthesis oil product;

(5) And (5) rectifying the water phase obtained in the step (4) to obtain a solvent component and an oxygen-containing compound aqueous solution in the extracting agent, returning the solvent component to the step (1) for reuse, and treating the oxygen-containing compound aqueous solution in sewage.

In the invention, the main components of the Fischer-Tropsch synthesis oil product in the step (1) are C5-C20 normal paraffin and normal olefin, and the rest components comprise isoparaffin and olefin. In some preferred embodiments, the fischer-tropsch synthesis oil can be a fischer-tropsch light oil, wherein the oxygen-containing compound comprises one or more of organic acid, alcohol, aldehyde, ketone and ester, and the total content of the oxygen-containing compound accounts for 1wt% to 10wt% of the total amount of the fischer-tropsch light oil.

In a preferred embodiment, the solvent in step (1) of the present invention is one or both of methanol and sulfolane.

In a further preferred embodiment, the extractant of step (1) may be a solvent mixture comprising 3wt% to 20wt% (e.g. 3wt% to 10wt%, 3.5wt% to 10 wt%) of desalted water or Fischer-Tropsch synthesis water. Preferably, the extractant is a mixture of Fischer-Tropsch synthesis water and the solvent. Fischer-Tropsch synthesis water is a byproduct of Fischer-Tropsch synthesis reaction, the amount of the Fischer-Tropsch synthesis water is very large, and various organic matters such as alcohol, aldehyde, ester, ketone, acid and the like (the organic matters account for 3-10 wt% of the total amount of the Fischer-Tropsch synthesis water, particularly methanol and ethanol are used as main materials) exist in the Fischer-Tropsch synthesis water, and the Fischer-Tropsch synthesis water is generally recycled after being subjected to water treatment in the prior art; however, the Fischer-Tropsch synthesis water is used directly in the process of the invention without prior water treatment. The extraction agent is constructed by using Fischer-Tropsch synthesis water, on one hand, the reuse of wastewater can be realized, so that the use amount of desalted water is reduced, on the other hand, methanol, ethanol and the like contained in the Fischer-Tropsch synthesis water can be used for removing oxygen-containing compounds in Fischer-Tropsch synthesis oil products, and the use amount of extra solvent components is saved.

In a preferred embodiment, in the step (1), the mass ratio of the extractant to the Fischer-Tropsch synthesis oil is (0.1-5): 1. Preferably, the mass ratio of the extractant to the Fischer-Tropsch synthesis oil product is (0.5-5) to 1, such as (0.5-3) to 1, (0.5-2) to 1, and (0.7-5) to 1.

In a preferred embodiment, the extraction separation in step (1) can be performed by using a centrifugal extractor, for example, by using a centrifugal extractor to perform extraction separation at a high speed of 100-3000 g; the extraction separation may also be performed using an extraction column, for example, by contact extraction of 2 or more stages using an extraction column. In this context, the separation efficiency can be further improved by performing the extraction separation by means of centrifugation.

By way of example, the centrifugal extractor can realize rapid mass transfer mixing between different liquids, namely, light and heavy two-phase solutions enter a mixing area in the shell of the centrifugal extractor from two feeding pipe orifices respectively according to a certain proportion, so that the two phases are rapidly mixed and dispersed to complete a mixing mass transfer process; the mixed liquid and the rotary drum rotate synchronously, and heavy phase liquid with high density gradually gets away from the center of the rotary drum and leans against the wall of the rotary drum in the upward flowing process under the action of centrifugal force; the light phase liquid with low density gradually gets away from the wall of the rotary drum and leans to the center, and the clarified two-phase liquid finally enters the collecting chamber through the respective weir plates and flows out from the light phase outlet and the heavy phase outlet to complete the two-phase separation process. In a preferred embodiment, the extraction separation is carried out with the centrifugal extractor at a centrifugal force of 100 to 3000g, preferably 500 to 2000g (e.g. 600 to 1500 g). Preferably, the extraction separation can adopt single-stage extraction, multi-stage cross-flow extraction or multi-stage counter-current extraction, and preferably multi-stage cross-flow extraction. In a more preferred embodiment, the number of extraction stages in the centrifugal extractor is 1 to 6, preferably 2 to 4 (e.g., 2 to 3). In this context, unless otherwise stated, the operating conditions for the centrifugal extraction separation are normal temperature and normal pressure.

In a further preferred embodiment, the extraction column is a continuous multiple extraction plant, which may be a packed extraction column, a sieve plate extraction column, a rotating disc extraction column, a vibrating extraction column, preferably a rotating disc extraction column. Wherein, the number of stages of the selected extraction column is 10 to 50, preferably 20 to 30. In this context, unless otherwise stated, the conditions for the extractive separation using the extraction column are normal temperature and normal pressure.

In this context, the raffinate phase obtained in step (1) is mainly composed of hydrocarbons, the content of which can reach over 99wt%, and the rest is trace oxygen-containing compounds and trace extractant; the main components of the extract phase obtained in the step (1) are an extracting agent, an oxygen-containing compound and trace hydrocarbons.

In a preferred embodiment, the water washing of step (2) is carried out in a wash column. In some preferred embodiments, the water wash is performed with desalted water to remove trace amounts of oxygenates and extractant from the raffinate phase, resulting in a fischer-tropsch synthesis oil phase and a wash water phase. In a further preferred embodiment, the mass ratio of the desalted water to the raffinate phase may be 1 to 1, and the number of washing times is 1 to 5, preferably 2 to 4. In some embodiments, the hydrocarbon content of the raffinate phase may be greater than 99.6wt% after washing with water.

In a preferred embodiment, the adsorptive separation in step (3) is carried out in an adsorption column, the purpose of the adsorptive separation being to further increase the hydrocarbon purity above 99.9 wt%. For the adsorption separation, a porous medium adsorbent with proper polarity, specific micropore size and certain particle size can be selected to further remove oxygen-containing organic matters in hydrocarbons, so that the content of the hydrocarbons is further increased. The adsorbent can be a resin, a molecular sieve or magnesium silicate, preferably a molecular sieve, further preferably a 13X series molecular sieve, and the mass ratio of the adsorbent to the fischer-tropsch synthesis oil phase obtained in step (2) is 1 to 1 (e.g. 1 to 2 to 1.

In a further preferred embodiment, the conditions of the adsorption separation in step (3) are a temperature of not higher than 50 ℃ (e.g., 30 ℃ to 50 ℃) and a pressure of 0.5 to 1MPa.

In a preferred embodiment, in the step (4), the oil-water separation is performed in an oil-water separator. Preferably, an upper oil phase and a lower water phase are obtained by standing in the oil-water separator, wherein the oil phase is recycled to the step (1) for extraction separation again. By this operation of recycling the oil phase, a small amount of hydrocarbons dissolved in water can be further recovered, so that the overall recovery rate of hydrocarbons can be up to 98wt% or more, thereby significantly improving the economy of the process.

In a further preferred embodiment, the oil-water separation in step (4) is carried out at a temperature of 30 to 50 ℃ for 20 to 60min (e.g., 30 to 60 min); under the condition, the problem of emulsification in the oil-water separator can be further avoided, and the separation of the oil phase and the water phase is facilitated.

In a preferred embodiment, the oil-water separation in step (4) is performed by using a centrifuge. Preferably, the oil-water separation is performed using a centrifuge at a centrifugal force of 300-1000 g.

In this context, step (5) is to obtain the extractant and the aqueous solution of the oxygen-containing compound by rectifying the aqueous phase, and its function is mainly to recover the solvent component in the extractant, so as to reduce the loss of the solvent component in the extractant, and to achieve the recovery and reuse of the solvent component, thereby improving the economy of the whole process flow.

In a further preferred embodiment, the rectification in step (5) is carried out in a rectification column (e.g. a tray rectification column) operating under the following conditions: 20 to 50 theoretical plates, reflux ratio of 2. Wherein the water solution of the oxygen-containing compound recovered by the rectifying tower is sent to sewage treatment, and the regenerated water can be continuously recycled, including but not limited to the use of the obtained regenerated water for preparing an extracting agent, the use of the regenerated water as circulating water of other devices in a factory, and the like.

In one embodiment, the invention relates to an apparatus for carrying out the above method, wherein the apparatus comprises: the device comprises an extraction separation unit, a water washing unit, an adsorption unit, an oil-water separation unit and a rectification unit which are sequentially connected in a fluid communication manner.

In some embodiments, the extractive separation unit is at least one of a centrifugal extractor or an extraction column.

In a further preferred embodiment, the number of extraction stages in the centrifugal extractor is 1 to 6, preferably 2 to 4. In a further preferred embodiment, the extraction column may be a packed extraction column, a sieve plate extraction column, a rotating disc extraction column, a vibrating extraction column, preferably a rotating disc extraction column. Wherein, the number of stages of the extraction column is 10 to 50, preferably 20 to 30.

In some embodiments, the water wash unit is a wash column.

In some embodiments, the adsorption unit is an adsorption column.

In some embodiments, the oil-water separation unit is an oil-water separator or a centrifuge.

In some embodiments, the rectification unit is a rectification column. In a further preferred embodiment, the rectification column has 20 to 50 theoretical plates, the reflux ratio is 2.

Exemplary aspects of the invention may be described by the following numbered paragraphs:

1. a method for deeply removing oxygen-containing compounds in Fischer-Tropsch synthesis oil products comprises the following steps:

2. The method of paragraph 1, wherein the fischer-tropsch derived oil product is a fischer-tropsch light oil, the oxygen-containing compound in the fischer-tropsch derived oil product comprises one or more of organic acids, alcohols, aldehydes, ketones, and esters, and the total content of the oxygen-containing compound accounts for 1wt% to 10wt% of the total amount of the fischer-tropsch light oil.

3. The process of paragraphs 1 or 2 wherein the solvent in step (1) is one or both of methanol and sulfolane.

4. The method of any of paragraphs 1 to 3, wherein the extractant of step (1) is a solvent mixture comprising 3 to 20wt% of desalted water or Fischer-Tropsch synthesis water.

5. The method of paragraph 4 wherein the extractant is a mixture of Fischer Tropsch synthesis water and the solvent.

6. The method as described in any one of paragraphs 1-5, wherein in step (1), the solvent-oil mass ratio of the extracting agent to the Fischer-Tropsch synthesis oil product is (0.1-5): 1.

7. The method of any of paragraphs 1-6, wherein the extraction separation of step (1) is performed using a centrifugal extractor or using an extraction column.

8. The method according to any one of paragraphs 1 to 7, wherein the extraction separation is performed with a centrifugal force of 100 to 3000g using the centrifugal extractor.

9. The method of paragraph 8 wherein the extractive separation is by single stage extraction, multi-stage cross-flow extraction or multi-stage counter-current extraction.

10. The method according to any one of paragraphs 7 to 9, wherein the number of extraction stages of the centrifugal extractor is 1 to 6.

11. The method of paragraph 7 wherein the extraction column is a packed extraction column, a sieve plate extraction column, a rotating disc extraction column, a vibrating extraction column.

12. The method of paragraph 7 or 11 wherein the number of stages of extraction column is selected from the range of 10 to 50.

13. The method of any of paragraphs 1-12, wherein the water washing of step (2) is performed in a wash column.

14. The method of paragraph 13 wherein the water wash is performed with desalted water.

15. The method of paragraph 14 wherein the mass ratio of the desalted water to the raffinate phase is 1 to 1 and the number of washes is 1 to 5.

16. The method of any of paragraphs 1-15, wherein the adsorptive separation of step (3) is performed in an adsorption column.

17. The method of any of paragraphs 1-16, wherein the adsorbent used for the adsorptive separation is a resin, a molecular sieve or magnesium silicate.

18. The method of paragraph 17 wherein the mass ratio of the adsorbent to the Fischer-Tropsch synthesis oil phase obtained in step (2) is from 1.

19. The method of any one of paragraphs 1-18, wherein the conditions for the adsorptive separation in step (3) are a temperature of not more than 50 ℃ and a pressure of 0.5 to 1MPa.

20. The method according to any one of paragraphs 1 to 19, wherein in step (4), the oil-water separation is performed in an oil-water separator.

21. The method of paragraph 20 wherein the oil-water separation of step (4) is carried out at a temperature of 30-50 ℃ for 20-60 min.

22. The method of any of paragraphs 1-19, wherein the oil-water separation of step (4) is performed using a centrifuge.

23. The method of paragraph 22 wherein the oil-water separation is performed using a centrifuge at a centrifugal force of 300-1000 g.

24. The method as claimed in any of paragraphs 1-23, wherein the rectification in step (5) is carried out in a rectification column operating under the conditions: 20 to 50 theoretical plates, reflux ratio of 2.

25. An apparatus for carrying out the method of any of paragraphs 1-24, wherein the apparatus comprises: the device comprises an extraction separation unit, a water washing unit, an adsorption unit, an oil-water separation unit and a rectification unit which are sequentially connected in a fluid communication mode.

26. An apparatus as paragraph 25 recites, wherein the extractive separation unit is at least one of a centrifugal extractor or an extraction column.

27. The apparatus of paragraph 25 or 26, wherein the centrifugal extractor has an extraction stage number of 1 to 6.

28. An apparatus as in any of paragraphs 25-27, wherein said extraction column is a packed extraction column, a sieve plate extraction column, a rotating disc extraction column, a vibrating extraction column.

29. The apparatus as in any one of paragraphs 25-28, wherein the number of stages of the extraction column is selected from the range of 10 to 50.

30. The apparatus of any of paragraphs 25-29, wherein the water wash unit is a wash tower.

31. The apparatus of any of paragraphs 25-30, wherein the adsorption unit is an adsorption column.

32. An apparatus as in any of paragraphs 25-31, wherein the oil-water separation unit is an oil-water separator or a centrifuge.

33. The apparatus of any of paragraphs 25-32, wherein said rectification unit is a rectification column.

34. The apparatus of any of paragraphs 25-33, wherein the rectification column has 20 to 50 theoretical plates and a reflux ratio of 2.

In the method for deeply removing the oxygen-containing compounds in the Fischer-Tropsch synthesis oil product, the Fischer-Tropsch synthesis oil product used as the raw material is firstly extracted and separated to enhance the separation effect of hydrocarbons and the oxygen-containing compounds; the raffinate phase obtained after extraction and separation can remove the oxygen-containing compounds to the maximum extent through water washing and adsorption separation processes to obtain a clean Fischer-Tropsch oil product (the purity of which can be more than 99.9 wt%). And for a small amount of Fischer-Tropsch synthesis oil product remained in the extraction phase, the hydrocarbon product is recovered through an oil-water separator, so that the overall hydrocarbon recovery rate of the process method is improved. The extractant medium introduced in the method can be recycled by a rectification separation mode, so that the requirement of continuously introducing the solvent component of the extractant is reduced. Therefore, the method provided by the invention has the advantages of high efficiency of removing the oxygen-containing compounds, high hydrocarbon recovery rate, simple process, higher benefit-cost ratio and the like.

Examples

Unless otherwise indicated, reagents, materials and devices referred to in the following examples are all commercially available as is conventional in the art; the conventional operations involved in the following examples can be found in patents, patent applications, publications, and the like, which are already published in the art. It will be understood by those skilled in the art that the scope of the present invention is not limited thereto but may be variously changed, modified and combined within the spirit and concept of the present invention.

Example 1

The Fischer-Tropsch synthesis oil product raw material 101 (the content of the oxygen-containing compound is 1.5 wt%) and the extracting agent are mixed in a centrifugal extractor, and the two phases are quickly mixed and dispersed under the action of centrifugal force to complete the mixing mass transfer process. The extractant flow and the Fischer-Tropsch synthesis oil raw material flow 101 are in contact mixing in a centrifugal extractor according to the mass ratio of the extractant to the oil of 0.7. The extractant stream used methanol and water as mixed extractants, wherein the methanol used industrial analytical pure methanol, the water used desalted water, and the water content in the extractant is 3.5wt%. The Fischer-Tropsch synthesis oil product stream 101 and the methanol-desalted water mixed extractant are subjected to cross-flow extraction for 2 times, and the centrifugal force of a centrifugal extractor is 600g.

The hydrocarbon content of raffinate stream 103 from the centrifugal extraction was 99.38wt%. Sending the raffinate phase material flow 103 to a water washing tower 2, washing the raffinate phase material flow by desalted water 104 at normal temperature and normal pressure, and further removing oxygen-containing compounds and methanol in the raffinate phase material flow; the mass ratio of desalted water 104 to raffinate stream 103 was 1. After 2 times of desalted water washing, the hydrocarbon content in the material flow 106 can reach more than 99.6 wt%. To further increase the hydrocarbon purity, stream 106 is sent to adsorption column 3 for further removal of oxygenates using polyvinylpyridine resin at 30 ℃ and 0.6MPa, the mass ratio of resin to stream 106 being 1. The hydrocarbon content in the material flow 107 after the absorption of the polyvinyl pyridine resin can reach more than 99.9 wt%.

The extract phase stream 108 obtained by centrifugal extraction consists mainly of methanol, water, oxygenates and trace hydrocarbons. Stream 105, obtained after the desalted water wash, is mainly composed of water, traces of oxygenates and methanol. The stream 108 and the stream 105 are sent to the oil-water separator 4 and are left standing at 40 ℃ for 30min to separate the two by utilizing the density difference between the oil and the water. The upper oil phase stream 109 of the oil-water separator 4 is recycled to the centrifugal extractor for recovering hydrocarbons again, and the lower water phase stream 110 is sent to the rectifying tower 5 for rectification under the conditions of 30 theoretical plates and a reflux ratio of 3. The methanol solvent 111 obtained from the rectifying tower 5 is recycled to be reused for preparing the extracting agent. The aqueous solution of the oxygen-containing compound obtained in the rectifying tower 5 is sent to a sewage treatment.

Example 2

The Fischer-Tropsch synthesis oil product raw material 101 (the content of the oxygen-containing compound is 5 wt%) and the extracting agent are mixed in the centrifugal extractor 1, and the two phases are quickly mixed and dispersed under the action of centrifugal force, so that the mixed mass transfer process is completed. In this embodiment, the extractant stream and the fischer-tropsch oil feedstock stream 101 are contacted and mixed in a centrifugal extractor according to a mass ratio of 3. The extractant stream uses methanol and water as mixed extractants, wherein the methanol uses industrial analytical pure methanol, the water uses desalted water, and the water content in the extractant is 10wt%. The Fischer-Tropsch synthesis oil product stream 101 and the methanol-desalted water mixed extractant are subjected to cross-flow extraction for 3 times, and the centrifugal force of a centrifugal extractor is 1500g.

The hydrocarbon content of raffinate stream 103 from the centrifugal extraction was 99.36wt%. The raffinate stream 103 is sent to a water washing tower 2, washed by desalted water 104 under normal temperature and pressure conditions, and further removed of oxygen-containing compounds and methanol. The mass ratio of desalted water 104 to raffinate stream 103 was 1. After 3 times of desalted water washing, the hydrocarbon content in the material flow 106 can reach more than 99.6 wt%. To further increase the hydrocarbon purity, stream 106 is sent to adsorption column 3 where further oxygenates are removed using 13X molecular sieves at 40 ℃ and 0.7 MPa. The mass ratio of the molecular sieve to stream 106 is 1. The hydrocarbon content in the material flow 107 after molecular sieve adsorption can reach more than 99.9 wt%.

The extract phase stream 108 obtained by centrifugal extraction consists mainly of methanol, water, oxygenates and trace hydrocarbons. Stream 105, obtained after the desalted water wash, is composed mainly of water, traces of oxygenates and methanol. The stream 108 and the stream 105 are sent to the oil-water separator 4 and are left standing at 30 ℃ for 40min to separate the two by utilizing the density difference between the oil and the water. The upper layer oil phase stream 109 of the oil-water separator 4 is circulated back to the centrifugal extractor for recovering hydrocarbons again, and the lower layer water phase stream 110 is sent to the rectifying tower 5 for rectifying under the conditions of 40 theoretical plates and a reflux ratio of 4. The methanol solvent 111 obtained from the rectifying tower 5 is recycled to be reused for preparing the extracting agent. The oxygen-containing compound aqueous solution obtained by the rectifying tower 5 is sent to sewage treatment.

Example 3

The Fischer-Tropsch synthesis oil product raw material 101 (the content of the oxygen-containing compound is 10 wt%) enters from the bottom of the rotating disc extraction tower 1, and the extracting agent enters from the top of the rotating disc extraction tower 1. After the variable speed motor is started, the disc rotates at a high speed and drives the two phases to rotate together. The theoretical stage number of the rotary disc extraction tower 1 is 30. Under the action of shearing force, the two phases are quickly mixed and dispersed to complete the mixing mass transfer process. In this embodiment, the extractant stream and the fischer-tropsch oil feedstock stream 101 are contacted and mixed in the rotating disk extraction tower 1 according to a 5-agent-to-oil mass ratio of 1. The extractant flow adopts sulfolane and water as mixed extractants, wherein the sulfolane is selected from industrial analytical pure water, desalted water is selected from water, and the water content in the extractant is 5wt%.

The hydrocarbon content of raffinate stream 103 from the extraction separation was 99.03wt%. The raffinate stream 103 is sent to a water washing tower 2, washed by desalted water 104 under normal temperature and pressure conditions, and further subjected to removal of oxygen-containing compounds and sulfolane. The mass ratio of desalted water 104 to raffinate stream 103 was 1. After 4 times of desalted water washing, the hydrocarbon content in the material flow 106 can reach more than 99.6 wt%. To further increase the hydrocarbon purity, stream 106 is sent to adsorption column 3 where further oxygenates are removed using 13X molecular sieves at 50 ℃ and 1MPa. The mass ratio of the molecular sieve to stream 106 is 1. The hydrocarbon content in the material flow 107 after molecular sieve adsorption can reach more than 99.9 wt%.

The extract phase stream 108 obtained by centrifugal extraction consists mainly of sulfolane, oxygenates and trace hydrocarbons. Stream 105, obtained after the desalted water wash, is composed mainly of water, trace oxygenates and sulfolane. The stream 108 and the stream 105 are sent to the oil-water separator 4 and are left standing at 50 ℃ for 60min to separate the two by utilizing the density difference between the oil and the water. The upper oil phase stream 109 of the oil-water separator 4 is recycled to the centrifugal extractor for recovering hydrocarbons again, and the lower water phase stream 110 is sent to the rectifying tower 5 for atmospheric rectification under the conditions of 50 theoretical plates and a reflux ratio of 2 to recover sulfolane in the extracting agent. . The sulfolane solvent 111 obtained from the rectifying tower 5 is recycled to be reused for preparing the extracting agent. The aqueous oxygenate solution 112 obtained in the rectifying tower 5 is sent to sewage treatment.

Example 4

The Fischer-Tropsch synthesis oil product raw material 101 (the content of the oxygen-containing compound is 3.5 wt%) and the extracting agent are mixed in the centrifugal extractor 1, and the two phases are quickly mixed and dispersed under the action of centrifugal force, so that the mixed mass transfer process is completed. In this example, the extractant stream and the fischer-tropsch oil feedstock stream 101 are in the following 2:1, and the mass ratio of the solvent to the oil is mixed in a contact manner in a centrifugal extractor. The extractant stream uses ethanol and water as mixed extractants, wherein the water uses Fischer-Tropsch synthetic water, the ethanol uses industrial analytical pure, and the water content in the extractant is 5wt%. The Fischer-Tropsch synthesis oil product stream 101 and the ethanol-Fischer-Tropsch synthesis water mixed extractant are subjected to cross-flow extraction for 3 times, and the centrifugal force of a centrifugal extractor is 1000g.

The hydrocarbon content of raffinate stream 103 from the centrifugal extraction was 99.15wt%. The raffinate stream 103 is sent to a water washing tower 2, washed by desalted water 104 under normal temperature and pressure conditions, and further removed of oxygen-containing compounds and ethanol. The mass ratio of desalted water 104 to raffinate stream 103 was 1. After 4 times of desalted water washing, the hydrocarbon content in the material flow 106 can reach more than 99.6 wt%. To further increase the hydrocarbon purity, stream 106 is sent to adsorption column 3 where further oxygenates are removed using 13X molecular sieves at 30 ℃ and 0.5 MPa. The mass ratio of the molecular sieve to stream 106 is 1. The hydrocarbon content in the material flow 107 after molecular sieve adsorption can reach more than 99.9 wt%.

The extract phase stream 108 obtained by centrifugal extraction consists mainly of ethanol, oxygenates and trace hydrocarbons. Stream 105, obtained after the desalted water wash, is mainly composed of water, trace oxygenates and ethanol. The stream 108 and the stream 105 are sent to the oil-water separator 4 and are left standing at 30 ℃ for 50min to separate the two by utilizing the density difference between the oil and the water. The upper oil phase stream 109 of the oil-water separator 4 is recycled to the centrifugal extractor for recovering hydrocarbons again, and the lower water phase stream 110 is sent to the plate rectifying tower 5 for rectification under the conditions of 20 theoretical plates and a reflux ratio of 5. The ethanol stream 111 obtained from the rectifying tower 5 is recycled to be reused for preparing the extracting agent. The oxygen-containing compound aqueous solution obtained by the rectifying tower 5 is sent to sewage treatment.

Claims

2. The method of claim 1, wherein the fischer-tropsch synthesis oil is fischer-tropsch light oil, and the oxygen-containing compounds in the fischer-tropsch synthesis oil comprise one or more of organic acids, alcohols, aldehydes, ketones, and esters, and the total content of the oxygen-containing compounds is 1wt% to 10wt% of the total amount of the fischer-tropsch light oil.

3. The method of claim 1 or 2, wherein the solvent in step (1) is one or both of methanol and sulfolane;

preferably, the extractant in the step (1) is a solvent mixture containing 3 to 20 weight percent of desalted water or Fischer-Tropsch synthesis water;

preferably, the extractant is a mixture of Fischer-Tropsch synthesis water and the solvent.

4. The method of any one of claims 1 to 3, wherein in the step (1), the mass ratio of the extractant to the Fischer-Tropsch synthesis oil product is (0.1-5): 1;

preferably, the extraction separation in the step (1) is carried out by using a centrifugal extractor or an extraction tower;

preferably, the centrifugal extractor is adopted to carry out extraction separation at a centrifugal force of 100-3000 g; preferably, the extraction separation adopts single-stage extraction, multi-stage cross-flow extraction or multi-stage countercurrent extraction, and more preferably, the extraction stage number of the centrifugal extractor is 1 to 6 times;

or preferably, the extraction tower is a packed extraction tower, a sieve plate extraction tower, a rotary disc extraction tower or a vibrating extraction tower, and the number of the selected extraction tower is preferably 10-50.

5. The process of any one of claims 1-4, wherein the water washing of step (2) is performed in a wash column;

preferably, the water washing is carried out by using desalted water, and more preferably, the mass ratio of the desalted water to the raffinate phase is 1.

6. The process of any one of claims 1-5, wherein the adsorptive separation of step (3) is carried out in an adsorption column; preferably, the adsorbent used for adsorption separation is resin, molecular sieve or magnesium silicate; more preferably, the mass ratio of the adsorbent to the fischer-tropsch synthesis oil phase obtained in step (2) is from 1 to 1;

preferably, the conditions of the adsorption separation in the step (3) are a temperature of not higher than 50 ℃ and a pressure of 0.5 to 1MPa.

7. The method according to any one of claims 1 to 6, wherein in the step (4), the oil-water separation is performed in an oil-water separator;

preferably, the oil-water separation in the step (4) is carried out at the temperature of 30-50 ℃ for 20-60 min;

preferably, the oil-water separation in the step (4) is carried out by using a centrifuge; preferably, the oil-water separation is performed using a centrifuge at a centrifugal force of 300-1000 g.

8. The method according to any one of claims 1-7, wherein the rectification in step (5) is carried out in a rectification column operating under the conditions: 20-50 theoretical plates, reflux ratio of 2.

9. An apparatus for carrying out the method of any one of claims 1-8, wherein the apparatus comprises: the device comprises an extraction separation unit, a water washing unit, an adsorption unit, an oil-water separation unit and a rectification unit which are sequentially connected in a fluid communication mode.

10. The apparatus of claim 9, wherein the extractive separation unit is at least one of a centrifugal extractor or an extraction column;

preferably, the extraction stage number of the centrifugal extractor is 1 to 6 times;

preferably, the extraction tower is a packing extraction tower, a sieve plate extraction tower, a rotary disc extraction tower or a vibration extraction tower, and the number of the selected extraction tower is preferably 10-50;

preferably, the water washing unit is a washing tower;

preferably, the adsorption unit is an adsorption column;

preferably, the oil-water separation unit is an oil-water separator or a centrifuge;

preferably, the rectification unit is a rectification column; preferably, the rectification column has 20 to 50 theoretical plates and a reflux ratio of 2.