Method and system for treating Fischer-Tropsch synthesis reaction water

Abstract

The present invention provides a method for treating Fischer-Tropsch synthesis reaction water and a system for implementing the method, which can treat Fischer-Tropsch synthesis reaction water in a resource-based and volume-reduced manner. The method of the present invention comprises pre-treating the Fischer-Tropsch synthesis reaction water to be treated by oil removal / solid removal, alcohol-acid conversion, acid organic matter removal, and cavitation deep treatment. The method for treating Fischer-Tropsch synthesis reaction water of the present invention can reasonably recycle oxygen-containing compounds in Fischer-Tropsch synthesis reaction water, and reasonably deeply treat the Fischer-Tropsch synthesis reaction water to meet sewage discharge standards, thereby solving the problems of low resource utilization, low utilization rate, unreasonable method, incomplete volume reduction, and secondary pollution in the existing Fischer-Tropsch synthesis reaction water treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of coal liquefaction, and in particular to a method for treating Fischer-Tropsch synthesis reaction water and a system for implementing the method. Background Art

[0002] Coal liquefaction is a long-term strategic measure for my country to solve the contradiction between oil supply and demand. The Fischer-Tropsch synthesis reaction is the core reaction of indirect coal liquefaction. Synthesis gas (H 2 +CO) is converted into hydrocarbon fuels and chemical raw materials under certain temperature and pressure through iron-based catalysts. Hydrocarbons of different chain lengths can be processed and modified to obtain gasoline, diesel, kerosene and other oil products and a variety of chemicals. Compared with other oil products, synthetic oil does not contain impurities such as sulfur, nitrogen, and nickel. It is a clean fuel that meets the strict requirements of modern engines and increasingly stringent environmental regulations.

[0003] While synthesizing hydrocarbon fuels, Fischer-Tropsch synthesis also produces a variety of organic oxygen-containing compounds (including but not limited to alcohols, acids, aldehydes and ketones, etc.), with a total content of about 1.0wt%-12.0wt%, and produces a large amount of water. Usually, more than one ton of Fischer-Tropsch synthesis reaction water is produced for every ton of oil produced. The oxygen-containing compounds dissolved in water are mainly low-carbon alcohols and acids, so the Fischer-Tropsch synthesis reaction water has the characteristics of strong acidity, strong corrosiveness, pungent odor, etc., which is not suitable for conventional sewage treatment methods. If the organic oxygen-containing compounds can be economically recovered or converted and utilized, the Fischer-Tropsch synthesis reaction water can be purified and recycled, which will not only reduce environmental pressure, but also improve the economic benefits of coal-to-oil projects.

[0004] CN100445222C discloses a method for treating Fischer-Tropsch synthesis reaction water, which first distills the Fischer-Tropsch synthesis reaction water to obtain a component rich in organic components (including organic acids), and the liquid rich in organic acids is subjected to liquid-liquid extraction to obtain organic acids; the extracted liquid is subjected to biochemical treatment, and during the biochemical treatment process, an alkaline salt is used to adjust and control the pH value of the water to obtain biochemically treated water; after the biochemically treated water is softened, purified water is obtained by liquid-solid separation, and the purified water still contains salts and organic components, and then high-purity water is obtained by desalination. The method disclosed in CN103523986B first de-oils the Fischer-Tropsch synthesis reaction water; the de-oiled Fischer-Tropsch synthesis reaction water is then neutralized by adding alkali; and then enters a distillation tower; a water-containing mixed alcohol is obtained at the top of the distillation tower, and synthetic wastewater is obtained at the bottom of the tower; the water-containing mixed alcohol is subjected to extraction and distillation to obtain light alcohol and heavy alcohol; and the subsequent treatment of the synthetic wastewater is carried out by biochemical treatment, desalination purification, evaporation, drying and other methods. The pH value of the Fischer-Tropsch synthesis reaction water can be increased quickly by using an alkali pretreatment process, but it is easy to introduce a large amount of salt and scaling salt ions, making it difficult to reuse the final purified water.

[0005] CN104150670B proposes a Fischer-Tropsch wastewater treatment method using a dealcoholization system and an extraction system, wherein a dealcoholization tower is used to remove alcohols (including light alcohols and heavy alcohols) from the Fischer-Tropsch wastewater, and then an extraction system is used to extract organic acids from the dealcoholized water, and a portion of the extractant-free wastewater from which the extractant is removed is used for the heavy alcohol washing step, and a portion is used for the coal gasification water-coal slurry water distribution or decontamination treatment system. In order to recover the heavy alcohol, this method requires washing the wastewater, which increases the amount of wastewater and thus increases the energy consumption of the system; on the other hand, the organic acid content in the Fischer-Tropsch synthesis water is low, and direct extraction and deacidification consumes a large amount of energy, and the extraction efficiency is low, and the efficiency of the extractant recovery unit is also reduced. Therefore, although the method disclosed in CN104150670B recovers some organic matter, it does not reduce the total amount of wastewater. CN103011373B utilizes ammonia-containing wastewater as a pH regulator instead of sodium hydroxide, and the Fischer-Tropsch synthesis reaction water is neutralized with the ammonia-containing wastewater to obtain pulping water; the pulping water and raw coal are made into water-coal slurry in a coal mill and sent to a gasifier, and the organic matter in the Fischer-Tropsch synthesis reaction water participates in the gasification reaction as a part of the reaction materials, so that the Fischer-Tropsch synthesis reaction water is finally treated, but this water treatment technology is easily limited by the selected gasification process.

[0006] The method disclosed in CN101190821B performs multi-effect evaporation on the Fischer-Tropsch synthesis reaction water after oil-water separation, and divides the Fischer-Tropsch synthesis reaction water into low-concentration water poor in organic matter and high-concentration water rich in organic matter, removes organic matter in the low-concentration water by reverse osmosis membrane separation technology, and treats the high-concentration water by condensation or flotation oil removal method. After the above treatment, if the chemical oxygen demand (COD) of the synthetic reaction water is low, most of the organic matter is removed by biochemical treatment process and then reused in circulating water. If the COD is high, it is directly reused in the synthesis gas production process. CN111533367A proposes a treatment device and method for Fischer-Tropsch synthesis reaction water, which uses permeation gasification membrane and rectification separation technology to realize the separation and concentration of alcohol, and most of the organic acid is trapped in the synthetic water. Further, by coupling anaerobic, aerobic and catalytic ozone oxidation, an acid wastewater biological conversion integrated process is constructed to realize the recovery of alcohol and the utilization of synthetic water resources. However, the current use of membrane separation technology to remove or recover low-concentration organic matter from water has problems such as low selectivity, low permeation flux and lack of suitable membrane materials. In addition, since the amount of water in the aqueous phase of the Fischer-Tropsch synthesis is quite large, the content of organic oxygen-containing compounds is not very high, and the alcohols in the organic oxygen-containing components except methanol all co-azeotropize with water. The use of distillation to further separate and recover the organic oxygen-containing compounds faces the possibility of constant boiling and co-azeotropy, consumes more energy, and it is more difficult to obtain qualified chemicals.

[0007] CN103044217A and CN102442882A propose a method for using distillation separation technology to orderly separate non-acidic oxygen-containing organic matter in Fischer-Tropsch synthesis reaction water, and finally obtain basic organic raw materials such as acetaldehyde, propionaldehyde, acetone, ethanol, n-propanol, and mixed alcohols. However, this process requires the integrated operation of multiple distillation towers, which is too cumbersome and consumes huge energy.

[0008] CN102381776B proposes a method for removing oxygenated organic matter from Fischer-Tropsch synthesis reaction water by catalytic hydrogenation. In this method, oxygenated organic matter in the synthesis reaction water is converted into C 1 -C 4 However, this technology is currently unable to solve the problems of catalyst performance and life in the aqueous phase hydrogenation process, making it difficult to achieve industrial application.

[0009] The method disclosed in CN102107985A oxidizes the oxygen-containing compounds in the Fischer-Tropsch synthesis reaction water into acids by adding oxidants and co-oxidants, then neutralizes the acid formed by oxidation with calcium oxide and calcium hydroxide to form calcium salt precipitates, and finally removes the calcium salt precipitates by filtering. On the one hand, the oxygen-containing compounds in the Fischer-Tropsch synthesis reaction water are mainly alcohols and acids, and the method does not recycle them, which loses the economic benefits of the coal-to-oil project to a certain extent; on the other hand, the addition of calcium oxide and calcium hydroxide increases the hardness of the water, and improper control of the filtering operation will cause scaling of subsequent pipelines and equipment, increase the salt content of the water and increase the load of the subsequent desalination system, and a large amount of chemical reagents need to be added, causing secondary pollution, increasing the cost of sewage treatment, and the organic matter in the wastewater is only partially removed, the reduction degree is low, and the emission standards are not met. Summary of the invention

[0010] The main purpose of the present invention is to provide a method for treating Fischer-Tropsch synthesis reaction water and a system for implementing the method, which can treat Fischer-Tropsch synthesis reaction water in a resource-based and volume-reduced manner, wherein resource-based means the rational recycling of oxygen-containing compounds in the Fischer-Tropsch synthesis reaction water; volume-reduction means rationally deep treating the Fischer-Tropsch synthesis reaction water to meet sewage discharge standards, so as to solve the problems existing in the existing Fischer-Tropsch synthesis reaction water treatment, such as low resource-based degree, low utilization rate, unreasonable method, incomplete volume-reduction degree, and secondary pollution.

[0011] In one aspect, the present invention provides a method for treating Fischer-Tropsch synthesis reaction water, the method comprising:

[0012] (1) performing oil removal / solid removal pretreatment on the Fischer-Tropsch synthesis reaction water to be treated to separate waste oil and solid particles from the Fischer-Tropsch synthesis reaction water, thereby obtaining oil-removed / solid-removed Fischer-Tropsch synthesis reaction water, wherein the petroleum content in the pretreated Fischer-Tropsch synthesis reaction water is ≤10 mg / L and the total oil content is ≤30 mg / L;

[0013] (2) performing alcohol-acid conversion on the pretreated Fischer-Tropsch synthesis reaction water, oxidizing the alcohol organic matter therein into acid organic matter, so as to obtain dealcoholized Fischer-Tropsch synthesis reaction water;

[0014] (3) extracting the Fischer-Tropsch synthesis reaction water after dealcoholization to remove the acidic organic matter therein to obtain deacidified Fischer-Tropsch synthesis reaction water, and collecting the obtained acid product;

[0015] (4) The deacidified Fischer-Tropsch synthesis reaction water is subjected to deep cavitation treatment to obtain purified Fischer-Tropsch synthesis reaction water.

[0016] Among them, the COD in the Fischer-Tropsch synthesis reaction water after purification Cr ≤100mg / L, pH=6-7.

[0017] On the other hand, the present invention provides a system for implementing the above method, namely, a treatment system for Fischer-Tropsch synthesis reaction water, wherein the system comprises: an oil removal / solid removal pretreatment unit, an alcohol acid conversion unit, an extraction deacidification recovery unit, and a cavitation deep treatment unit.

[0018] The Fischer-Tropsch synthesis reaction water treatment method of the present invention can achieve the treatment of Fischer-Tropsch synthesis reaction water in a resource-saving and volume-reducing manner, which specifically brings the following technical advantages:

[0019] (1) The method of the present invention realizes resource recovery of Fischer-Tropsch synthesis reaction water and reduction of wastewater treatment. Specifically, the alcohol organic matter in the Fischer-Tropsch synthesis reaction water is oxidized and converted into acid organic matter, and the concentration of acidic oxygen-containing compounds is increased, which is beneficial to improving the extraction efficiency of acid organic matter in the Fischer-Tropsch synthesis reaction water, thereby reducing the types and contents of organic matter in the Fischer-Tropsch synthesis reaction water and reducing the extraction cost.

[0020] The Fischer-Tropsch synthesis reaction water purified by the method of the present invention can be recycled as cooling water or boiler water. (2) Cavitation deep treatment relies on orifice plates, venturi cavitators, cyclone cavitators and ultrasonic cavitation devices to produce cavitation in water, which has the advantages of simple operation, small footprint, high oxidation efficiency, etc. In comparison, the conventional biochemical treatment used in the prior art requires carbon sources, nitrogen sources, and phosphorus sources as nutrients for sludge cultivation. The biological anaerobic and aerobic reaction rates are slow and require a long reaction time. Therefore, it is necessary to build a biochemical pool with a large footprint to increase the wastewater retention time. In addition, since the pH of the Fischer-Tropsch synthesis reaction water is low, alkali neutralization is required to enable the biochemical treatment to proceed.

[0021] However, the present invention avoids the introduction of a large amount of salt in the alkali neutralization process, and the nitrogen-containing (such as carbon amide, urea, ammonia or ammonium salts, etc.) and phosphorus-containing (such as phosphates such as sodium dihydrogen phosphate) substances that accelerate microbial degradation in the biochemical treatment unit, thereby reducing the generation of neutralization precipitates and biochemical sludge in the wastewater treatment process, while reducing subsequent desalination purification, evaporation, drying and other processes, thereby achieving a reduction in energy consumption and waste generation in the Fischer-Tropsch synthesis reaction water treatment.

[0022] (3) The acidic organic matter in the Fischer-Tropsch synthesis reaction water is recovered by extraction. The extraction reaction is a reversible reaction that can be controlled by temperature changes, which enables the recycling of the extractant. The operation is simple, the investment and operating costs can be reduced by about 40%, and it is easy to industrialize.

[0023] (4) The acidic organic matter in the synthetic water was recovered by extraction, which reduced the COD of the wastewater. At the same time, one of the main components of the Fischer-Tropsch synthesis reaction water is acetic acid, and the oxidation reaction rate constant of acetic acid is relatively low (2.14×10 -5 s -1 The present invention recovers acidic organic matter, indirectly improving the reaction rate of subsequent cavitation deep treatment of oxidized organic pollutants, and has the advantages of energy saving and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a method according to the invention is shown.

[0025] Figure 2 A schematic diagram of a system for implementing the method according to the present invention is shown.

[0026] Among them, the reference numerals are: 1. oil removal / solid removal pretreatment unit; 2. alcohol acid conversion unit (oxidation reactor); 3. oxidant tank; 4. extraction reaction device; 5. extraction agent adjustment tank; 6. product recovery device; 7. cavitation deep treatment unit;

[0027] 101. Fischer-Tropsch synthesis reaction water stream to be treated; 102. Fischer-Tropsch synthesis reaction water stream after oil / solid removal; 103. Oxidant input to alkyd acid conversion unit stream; 104. Fischer-Tropsch synthesis reaction water stream after dealcoholization (alkyd acid conversion); 105. Extractant input stream; 106. Fischer-Tropsch synthesis reaction water (raffinate phase) stream after deacidification; 107. Extractant recycling stream; 108. Extract phase outflow stream; 109. Acid product stream; 110. Oxidant input to cavitation deep treatment unit stream; 111. Purified Fischer-Tropsch synthesis reaction water stream. DETAILED DESCRIPTION

[0028] Exemplary embodiments are described below, but the protection scope of the present invention is not limited to these embodiments.

[0029] The term "Fischer-Tropsch synthesis reaction water" refers to water generated by the Fischer-Tropsch synthesis reaction, or water generated by the Fischer-Tropsch synthesis reaction that has been partially pretreated (but cannot be directly discharged or utilized and requires further treatment), or a mixture thereof. The pretreatment refers to a preliminary treatment method such as phase separation, and the Fischer-Tropsch synthesis reaction water that has been preliminarily treated can neither meet the discharge requirements nor be recycled. The "Fischer-Tropsch synthesis reaction" described herein includes Fischer-Tropsch synthesis reactions known in the prior art, such as high-temperature Fischer-Tropsch synthesis reactions and low-temperature Fischer-Tropsch synthesis reactions.

[0030] The term "alcohol organic matter" refers to alcohol organic matter dissolved in the Fischer-Tropsch synthesis reaction water during the Fischer-Tropsch reaction, including but not limited to methanol, ethanol, propanol, pentanol, butanol, hexanol, etc.

[0031] The term "acidic organic matter" refers to the acidic organic matter dissolved in the Fischer-Tropsch synthesis reaction water during the Fischer-Tropsch reaction and the acidic organic matter oxidized from the alcoholic organic matter in the Fischer-Tropsch synthesis reaction water, including but not limited to formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, etc.

[0032] The term "chemical oxygen demand (COD Cr )" refers to the oxygen demand measured using potassium dichromate as an oxidant, that is, the COD value measured using the potassium dichromate method, which represents the content of organic matter.

[0033] The term "acid product" refers to acidic organic matter that can be recovered by extraction, including but not limited to formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, etc.

[0034] In the present invention, the meaning and determination of petroleum and total oil in the Fischer-Tropsch synthesis reaction water refer to the industry standard HJ637-2012.

[0035] In one aspect, the present invention provides a method for treating Fischer-Tropsch synthesis reaction water, the method comprising:

[0036] (1) performing oil removal / solid removal pretreatment on the Fischer-Tropsch synthesis reaction water to be treated to separate waste oil and solid particles from the Fischer-Tropsch synthesis reaction water, thereby obtaining oil-removed / solid-removed Fischer-Tropsch synthesis reaction water, wherein in the oil-removed / solid-removed Fischer-Tropsch synthesis reaction water, petroleum is ≤10 mg / L and total oil is ≤30 mg / L;

[0037] (2) performing alcohol-acid conversion on the Fischer-Tropsch synthesis reaction water after oil / solid removal, oxidizing the alcohol organic matter in the Fischer-Tropsch synthesis reaction water after oil / solid removal into acid organic matter in the presence of an oxidant to obtain the Fischer-Tropsch synthesis reaction water after dealcoholization (alcohol-acid conversion);

[0038] (3) extracting the dealcoholized Fischer-Tropsch synthesis reaction water in the presence of an extractant to remove the acidic organic matter therein to obtain deacidified Fischer-Tropsch synthesis reaction water, and purifying and / or separating and collecting the acid in the acid-containing extractant to obtain an acid product;

[0039] (4) The deacidified Fischer-Tropsch synthesis reaction water is subjected to deep cavitation treatment in the presence of an oxidant, thereby obtaining purified Fischer-Tropsch synthesis reaction water.

[0040] In the present invention, the pH of the Fischer-Tropsch synthesis reaction water before treatment is about 2-4, and the COD of the Fischer-Tropsch synthesis reaction water after treatment by the method of the present invention is Cr ≤100mg / L, pH is about 6-7.

[0041] In a specific embodiment, the COD of untreated Fischer-Tropsch synthesis reaction water is Cr The value is greater than 5000 mg / L and less than or equal to 100000 mg / L, preferably COD Cr The value is greater than 5000 mg / L to less than or equal to 50000 mg / L, more preferably COD Cr The value is greater than 5000 mg / L to less than or equal to 30000 mg / L.

[0042] In the present invention, the petroleum in the Fischer-Tropsch synthesis reaction water to be treated (eg, to remove oil / solids) is ≤100 mg / L, the total oil is ≤500 mg / L, and the pH is about 2-4.

[0043] In step (1), waste oil and solid particles (e.g., catalyst, pipeline dirt, rust) are separated from the Fischer-Tropsch synthesis reaction water by oil removal / solid removal pretreatment to achieve a preliminary reduction treatment of the Fischer-Tropsch synthesis reaction water. In the present invention, the purpose of solid removal is also to remove oil, and the solid particles absorb a large amount of dispersed oil.

[0044] In a specific embodiment, the Fischer-Tropsch synthesis reaction water to be treated can be pumped into a device for oil removal / solid removal for pretreatment. In the present invention, any oil removal / solid removal method in the art can be adopted, as long as it can obtain the corresponding oil-removed / solid-removed Fischer-Tropsch synthesis reaction water. In a preferred embodiment, in step (1), the Fischer-Tropsch synthesis reaction water from the Fischer-Tropsch synthesis unit is first subjected to solid removal (e.g., filtration or centrifugal solid removal) and then oil removal.

[0045] In a preferred embodiment, the oil removal treatment can be carried out by one or more devices selected from the following: a coalescence oil removal device, a flotation oil removal device, a membrane filtration oil removal device and a hydrocyclone oil removal device; preferably, it is carried out by one or more devices selected from the following: a coalescence oil removal device, a flotation oil removal device and a membrane filtration oil removal device; more preferably, a coalescence oil removal device and / or a flotation oil removal device.

[0046] In a preferred embodiment, the oil removal device may further include a buffer tank, a filtering device, and related pipelines and a delivery pump. In the present invention, preferably, the petroleum in the Fischer-Tropsch synthesis reaction water after oil / solid removal is ≤10 mg / L, preferably ≤5 mg / L, and the total oil is ≤30 mg / L, preferably ≤20 mg / L; or, preferably, there is no or almost no solid particles in the Fischer-Tropsch synthesis reaction water after oil / solid removal, or the amount of solid particles therein is preferably less than 1 mg / L.

[0047] In step (2), the alcohol organic matter in the deoiled / desolidified Fischer-Tropsch synthesis reaction water is oxidized into acid organic matter in the presence of an oxidant to increase the concentration of acid organic matter in the Fischer-Tropsch synthesis reaction water and reduce the total amount of alcohol organic matter.

[0048] In a specific embodiment, the amount of alcohol organic matter in the Fischer-Tropsch synthesis reaction water after oil / solid removal may be 1000 mg / L-30000 mg / L; the amount of acid organic matter may be 900 mg / L-15000 mg / L.

[0049] In a preferred embodiment, the alkyd acid conversion device (ie, oxidation reactor) can be selected from kettle type, tower type or tank type reactor.

[0050] In a preferred embodiment, the oxidant can be selected from one or more of the following: ozone, Fenton's reagent (hydrogen peroxide + ferrous sulfate), hydrogen peroxide, sodium persulfate, peracetic acid, chlorine dioxide, potassium permanganate and potassium dichromate; preferably selected from one or more of the following: ozone, Fenton's reagent, hydrogen peroxide and sodium persulfate; more preferably ozone and / or hydrogen peroxide.

[0051] In the present invention, in step (2), the alkyd conversion can be carried out under the following conditions: the reaction time can be adjusted according to the alkyd conversion rate, the hourly conversion rate is controlled to be below 50%, and the oxidation can be stopped when the total alkyd conversion rate is greater than 80%, for example, the reaction time can be 1-10 hours; the gas phase oxidant pressure is controlled at 0.1MPa-1MPa; the liquid-solid oxidant pressure is normal pressure; the reaction temperature is 10-60°C, preferably 20-40°C; the total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is controlled to be 1000mg / L-20000mg / L, preferably 2000mg / L-20000mg / L, 5000mg / L-20000mg / L, and 2000mg / L-10000mg / L.

[0052] In the present invention, the alcohol organic matter in the Fischer-Tropsch synthesis reaction water may include but is not limited to: methanol, ethanol, propanol, pentanol, butanol, hexanol, etc. In the present invention, the acid organic matter obtained by conversion may include but is not limited to: formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, etc.

[0053] In step (2), more than 80% of the alcohol organic matter is converted into acid organic matter. In the present invention, GB16631-2008 is used to determine the alcohol acid composition and calculate the conversion rate.

[0054] Preferably, the amount of alcohol organic matter in the Fischer-Tropsch synthesis reaction water after dealcoholization (alcohol-acid conversion) may be 100 mg / L-10000 mg / L, preferably 1000 mg / L-5000 mg / L, and the amount of acid organic matter may be 14000 mg / L-50000 mg / L, preferably 20000 mg / L-40000 mg / L.

[0055] In step (3), the dealcoholized Fischer-Tropsch synthesis reaction water is extracted in the presence of an extractant to remove the acid therein to obtain deacidified Fischer-Tropsch synthesis reaction water, and the acid in the acid-containing extractant is purified and / or separated and collected to obtain an acid product, thereby realizing the resource recovery of oxygen-containing compounds in the Fischer-Tropsch synthesis reaction water.

[0056] In the present invention, the amount of acidic organic matter in the Fischer-Tropsch synthesis reaction water after deacidification may be 100 mg / L-1100 mg / L, preferably 100 mg / L-1000 mg / L, 100 mg / L-800 mg / L, or 100 mg / L-500 mg / L.

[0057] In some embodiments, the extraction process is carried out in an extraction reaction device. In a preferred embodiment, the extraction reaction device can be selected from one or more of the following: a multi-stage centrifugal extractor, an extraction tank, and an extraction tower.

[0058] The extractant may be selected from trialkylamines, tributyl phosphate, trioctylamine, trialkylphosphine oxide, trioctylphosphine oxide, or any mixture thereof.

[0059] In step (3), the extractant can be diluted with a diluent to improve the physical properties of the organic phase of the extractant (reduce viscosity, increase fluidity, change the density of the organic phase, and increase the density difference to facilitate separation). As a preferred technical solution, the diluent can be selected from toluene, benzene, cyclohexane, kerosene, n-octanol, or any mixture thereof. In a specific embodiment, in step (3), the mass ratio of the extractant to the diluent can be 10:1 to 1:10. In step (3), the mass ratio (compared to) of the organic phase and the aqueous phase during the extraction process can be 2:1 to 1:2, wherein the organic phase refers to the extractant or the extractant diluted with a diluent, and the aqueous phase refers to the Fischer-Tropsch synthesis reaction water after dealcoholization (alcohol-acid conversion).

[0060] In step (3), the reaction conditions of the extraction are: extraction at room temperature (room temperature in this article refers to about 25° C.) and mixing time of 30 min-60 min.

[0061] In the present invention, the extractant containing acid is called the extraction phase; the Fischer-Tropsch synthesis reaction water after deacidification is called the raffinate phase. In step (3), the extraction phase and the raffinate phase are separated, for example, by centrifugation, cyclone separation, or sedimentation separation.

[0062] In the present invention, the recovery of the acidic organic matter from the extraction phase can be carried out in an extraction tower with a plate number of 40-60, a tower top temperature of 40-120°C, a tower bottom temperature of 80-250°C, and a tower pressure of 10-50 kPa. The preferred reaction temperature is 100-203°C, the boiling point of the acidic organic matter; during the vacuum extraction distillation, the temperature can be reduced to below the boiling point, and the temperature decreases by 5°C for every 10 kPa of vacuum. In a preferred embodiment, the extractant from which the acid has been removed is returned to step (3) for recycling.

[0063] In step (3), the amount of acidic organic matter in the Fischer-Tropsch synthesis reaction water after deacidification is 100 mg / L-1100 mg / L, preferably 100 mg / L-1000 mg / L, 100 mg / L-800 mg / L, or 100 mg / L-500 mg / L.

[0064] In step (4), the deacidified Fischer-Tropsch synthesis reaction water is subjected to cavitation deep treatment in the presence of an oxidant. When the oxidant is added to the cavitation deep treatment device, the oxidant will produce more hydroxyl radicals with stronger oxidizing properties than itself under this sudden and drastic microenvironment, further removing organic pollutants in the Fischer-Tropsch synthesis reaction water, so that the treated Fischer-Tropsch synthesis reaction water meets the sewage discharge standard. In step (4), the oxidant can use the oxidant in step (2). In a preferred embodiment, the amount of the oxidant used can be 100-100000 mg / L.

[0065] Due to the high pressure and high temperature conditions generated by the cavitation effect, the mixing of strong oxidizing substances and strong turbulence greatly promotes the dissolution or mixing of reactants (such as oxidants and catalysts), accelerates the reaction rate, and strengthens the generation of free radicals such as OH, thereby greatly improving the degradation rate and reducing the reaction time and cost, that is, reducing the amount of water in the Fischer-Tropsch synthesis reaction.

[0066] Cavitation deep treatment relies on orifice-type cavitators, venturi-type cavitators, cyclone-type cavitators, ultrasonic devices, etc. to produce cavitation in water. When the bubbles produced by fluid cavitation move and collapse in the liquid, they produce local high temperature (the hot spot temperature in the bubble is 4700-5700K, and the bubble wall temperature is about 1900K), high pressure (bubble pressure above 50MPa), shock waves, high-speed jets and other extreme physical conditions. Such high temperature and pressure conditions are enough to open the OH bonds in water molecules, causing the water molecules to directly split into ·H and ·OH free radicals, which can further generate H 2 O 2 . Active free radicals and oxidizing substances with strong oxidizing properties exist in the gas phase region inside the cavitation bubble, the interface layer region near the bubble wall, and the surrounding liquid phase region at normal temperature and pressure, thereby achieving chemical bond breaking, high-temperature decomposition, and free radical oxidation reactions of organic pollutants. When an oxidant is added to the cavitation reactor, the oxidant will produce more hydroxyl radicals with stronger oxidizing properties than itself in this suddenly and drastically changing microenvironment, further removing organic pollutants from the Fischer-Tropsch synthesis reaction water.

[0067] In step (4), the cavitation deep treatment is carried out under the following conditions: operating temperature 15-50°C, preferably 20-40°C; reaction time 10-180 min, preferably 60-120 min.

[0068] In a preferred embodiment, the cavitation deep treatment device can be selected from one or more of the following: a Venturi-type hydraulic cavitation device, a cyclone-type hydraulic cavitation device, a orifice-type hydraulic cavitation device, and an ultrasonic cavitation device.

[0069] In a preferred embodiment, the cavitation deep treatment device may further include a buffer tank, an input pump, and the like.

[0070] On the other hand, the present invention provides a system for implementing the above method, namely, a system for treating Fischer-Tropsch synthesis reaction water, wherein the system comprises: an oil removal / solid removal pretreatment unit, an alcohol acid conversion unit, an extraction deacidification recovery unit, and a cavitation deep treatment unit.

[0071] In some embodiments, the oil removal / solid removal pretreatment unit includes a solid removal device and an oil removal device. For example, the solid removal device can be selected from a filter (such as a membrane filter), a centrifuge, etc. For example, the oil removal device can be selected from: a coalescence oil removal device, an air flotation oil removal device, a membrane filtration oil removal device, and a hydrocyclone oil removal device; preferably, a coalescence oil removal device, an air flotation oil removal device, and a membrane filtration oil removal device; more preferably, a coalescence oil removal device and / or an air flotation oil removal device.

[0072] In a preferred embodiment, the oil removal / solid removal pretreatment unit may further include a buffer tank, a filtering device, and related pipelines and a delivery pump.

[0073] In some embodiments, the alkyd conversion unit comprises an alkyd conversion device (ie, an oxidation reactor). In some embodiments, the alkyd conversion device can be selected from a kettle, a tower, or a tank reactor.

[0074] In a preferred embodiment, the system for treating Fischer-Tropsch synthesis reaction water may further comprise an oxidant tank for storing and providing an oxidant.

[0075] In some embodiments, the extraction deacidification recovery unit comprises: an optional product recovery device. In a preferred embodiment, the product recovery device can be selected from one or more of the following: a multi-stage centrifugal extractor, an extraction tank, and an extraction tower.

[0076] In a preferred embodiment, the extractive deacidification recovery unit further comprises an extractant regulating tank to store and regulate the extractant.

[0077] In a preferred embodiment, the cavitation deep treatment device can be selected from one or more of the following: a Venturi-type hydraulic cavitation device, a cyclone-type hydraulic cavitation device, a orifice-type hydraulic cavitation device, and an ultrasonic cavitation device.

[0078] In a preferred embodiment, the cavitation deep treatment device may further include a buffer tank, an input pump, and the like.

[0079] The following combination Figure 2 The scheme of the present invention is further illustrated by examples.

[0080] The Fischer-Tropsch synthesis reaction water 101 enters the oil removal / solid removal pretreatment unit 1 to perform pretreatment of the Fischer-Tropsch synthesis reaction water, including oil removal and solid removal; the pretreated Fischer-Tropsch synthesis reaction water 102 enters the alcohol-acid conversion unit 2, and the alcohol organic matter in the Fischer-Tropsch synthesis reaction water is oxidized into acid organic matter in the presence of the oxidant 103 from the oxidant tank 3, thereby completing the alcohol-acid conversion; the Fischer-Tropsch synthesis reaction water 104 after dealcoholization (alcohol-acid conversion) enters the extraction reaction device 4, and the extractant from the extractant regulating tank 5 is used to extract the alcohol organic matter. The agent 105 extracts the acid in the Fischer-Tropsch synthesis reaction water into the extractant phase (extraction phase), the acid-containing extraction phase 108 enters the product recovery device 6, the regenerated extractant 107 after the extraction agent is purified is further reused, and the obtained acid product 109 is collected; the Fischer-Tropsch synthesis reaction water (extraction phase) after deacidification enters the cavitation deep treatment unit 7, and is synergistically oxidized with the oxidant 110 from the oxidant tank 3 in the unit 7 to finally obtain the purified Fischer-Tropsch synthesis reaction water 111.

[0081] Example

[0082] The present invention is further described below with reference to examples, and embodiments of the present invention include but are not limited to the following examples.

[0083] Example 1

[0084] The Fischer-Tropsch synthesis reaction water (101) to be treated is filtered to remove solids at a pressure of 0.1 MPa and a temperature of 25°C; and then pumped into a coalescence oil removal device (1) for oil removal, wherein the oil removal pretreatment conditions are a temperature of 25°C and a pressure of 0.1 MPa. The petroleum in the Fischer-Tropsch synthesis reaction water after pretreatment is ≤10 mg / L, and the total oil is ≤30 mg / L.

[0085] Then, the pretreated Fischer-Tropsch synthesis reaction water (102) is fed into a tank oxidation reactor (2) and alcohol-acid conversion is carried out in the presence of an oxidant (103) from an oxidant tank (3), and the reaction conditions are: reaction temperature 25°C, residence time 30 minutes, oxidant (103) is ozone, and the total dissolved amount of ozone in the Fischer-Tropsch synthesis reaction water is 5000 mg / L. The conversion rate of alcohol organic matter into acid organic matter is 82%.

[0086] The Fischer-Tropsch synthesis reaction water (104) after dealcoholization is sent to a four-stage centrifugal extractor (4) and centrifuged in the presence of an extractant (105) from an extractant regulating tank (5). The reaction conditions are: extraction at room temperature (25°C) and a mixing time of 30 minutes. The selected extractant (105) is a mixture of trialkylamine and diluent benzene, the ratio of the extractant to the aqueous phase is 1:1, and the mass ratio of trialkylamine to benzene is 10:1. The acid removal rate is 98.3%.

[0087] The deacidified Fischer-Tropsch synthesis reaction water (106) is sent to a venturi-type cavitator (7) to be subjected to a cavitation deep treatment with an oxidant (110) from an oxidant tank (3), wherein the reaction conditions are: an operating temperature of 45°C, a reaction time of 50 minutes, an oxidant (110) is ozone, and the total dissolved amount of the oxidant in the Fischer-Tropsch synthesis water is 20,000 mg / L. The purified Fischer-Tropsch synthesis reaction water (111) flowing out of the venturi-type cavitator (7) has a COD of ≤100 and a pH of 6.92.

[0088] The acid-containing extraction phase (108) is sent to a product recovery device (6). The product recovery device has 50 plates, a tower top temperature of 55° C., a tower bottom temperature of 110° C., and a tower pressure of 20 kPa. The regenerated extractant (107) flows out from the bottom of the product recovery device (6) and circulates into a four-stage centrifugal extractor (4) for reuse. The acid product (109) is distilled from the top of the product recovery device tower (6). The mass fraction of the acid product is greater than 95%, wherein the purity of the acetic acid product is 97%, and the purity of the propionic acid product is 96%.

[0089] Example 2

[0090] The Fischer-Tropsch synthesis reaction water (101) to be treated is centrifuged to remove solids at a pressure of 0.2 MPa and a temperature of 25° C., and then pumped into a flotation oil removal device (1) for oil removal treatment, wherein the oil removal pretreatment conditions are a temperature of 30° C. and a pressure of 0.1 MPa. The petroleum in the Fischer-Tropsch synthesis reaction water after pretreatment is ≤8 mg / L, and the total oil is ≤27 mg / L.

[0091] Then, the pretreated Fischer-Tropsch synthesis reaction water (102) is fed into a kettle oxidation reactor (2) and alcohol-acid conversion is carried out in the presence of an oxidant (103) from an oxidant tank (3). The reaction conditions are: reaction temperature 28° C., residence time 60 min, hydrogen peroxide is selected as the oxidant, and the total dissolved amount of hydrogen peroxide in the Fischer-Tropsch synthesis reaction water is 5000 mg / L. The conversion rate of alcohol organic matter into acid organic matter is 85.9%.

[0092] The Fischer-Tropsch synthesis reaction water (104) after dealcoholization is sent to an extraction tank (4) and extracted in the presence of an extractant (105) from an extractant regulating tank (5). The reaction conditions are: extraction at room temperature (25°C) and a mixing time of 30 minutes. The selected extractant (105) is a mixture of trioctylamine and diluent cyclohexane, the ratio of the extractant to the aqueous phase is 1:2, and the mass ratio of trioctylamine to cyclohexane is 7:2. The acid removal rate is 99.5%.

[0093] The deacidified Fischer-Tropsch synthesis reaction water (106) is sent to a cyclone-type cavitator (7) to be subjected to a cavitation deep treatment with an oxidant (110) from an oxidant tank (3), wherein the reaction conditions are: an operating temperature of 38°C, a reaction time of 80 minutes, the selected oxidant (110) is hydrogen peroxide, and the total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is 20,000 mg / L. The purified Fischer-Tropsch synthesis reaction water (111) flowing out of the cyclone-type cavitator (7) has a COD of ≤100 and a pH of 6.88.

[0094] The acid-containing extraction phase (108) is sent to a product recovery device (6). The number of tower plates of the product recovery device (6) is 55, the tower top temperature is 40°C, the tower bottom temperature is 95°C, and the tower pressure is 25 kPa. The regenerated extractant (107) flows out from the bottom of the product recovery device (6), and the acid product (109) is distilled from the top of the product recovery device (6). The mass fraction of the acid product (109) is greater than 95%, wherein the purity of the acetic acid product is 96%, and the purity of the propionic acid product is 97%.

[0095] Example 3

[0096] The Fischer-Tropsch synthesis reaction water (101) to be treated is pumped into an oil removal / solid removal pretreatment device (1) for first centrifugal solid removal pretreatment and then membrane filtration oil removal, wherein the pretreatment conditions are a temperature of 28° C. and a pressure of 0.1 MPa. The petroleum in the Fischer-Tropsch synthesis reaction water after the pretreatment is ≤6 mg / L, and the total oil is ≤25 mg / L.

[0097] Then, the pretreated Fischer-Tropsch synthesis reaction water (102) is fed into a tower oxidation reactor (2) and alcohol-acid conversion is carried out in the presence of an oxidant (103) from an oxidant tank (3), and the reaction conditions are: reaction temperature 26°C, residence time 50 min, the selected oxidant (103) is sodium persulfate, and the total dissolved amount of sodium persulfate in the Fischer-Tropsch synthesis reaction water is 5000 mg / L. The conversion rate of alcohol organic matter into acid organic matter is 84.9%.

[0098] The Fischer-Tropsch synthesis reaction water (104) after dealcoholization is sent to an extraction tower (4) and extracted in the presence of an extractant (105) from an extractant regulating tank (5). The reaction conditions are: extraction at room temperature (25°C) and a mixing time of 30 minutes. The selected extractant (105) is a mixture of tributyl phosphate and diluents n-octanol and kerosene. The ratio of the extractant to the aqueous phase is 2:1, and the mass ratio of tributyl phosphate to n-octanol and kerosene is 3:7. The acid removal rate is 99.5%.

[0099] The deacidified Fischer-Tropsch synthesis reaction water (106) is sent to a perforated plate cavitator (7) to be subjected to a cavitation deep treatment with an oxidant (110) from an oxidant tank (3), wherein the reaction conditions are: an operating temperature of 20°C, a reaction time of 120 minutes, the selected oxidant (110) is sodium persulfate, and the total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is 20,000 mg / L. The purified Fischer-Tropsch synthesis reaction water (111) flowing out of the perforated plate cavitator (7) has a COD of ≤100 and a pH of 6.90.

[0100] The acid-containing extraction phase (108) enters the product recovery device (6). The number of plates of the product recovery tower (6) is 50, the tower top temperature is 65° C., the tower bottom temperature is 120° C., and the pressure in the tower is 20 kPa. The regenerated extractant (107) flows out from the bottom of the product recovery tower (6), and the carboxylic acid product is distilled from the top of the product recovery tower (6). The mass fraction of the acid product is greater than 95%, wherein the purity of the acetic acid product is 97%, and the purity of the propionic acid product is 96%.

[0101] Example 4

[0102] The Fischer-Tropsch synthesis reaction water (101) to be treated is pumped into the oil removal / solid removal pretreatment device (1), firstly subjected to filtering and solid removal pretreatment, and then subjected to hydrocyclone oil removal pretreatment, wherein the pretreatment conditions are a temperature of 22° C. and a pressure of 0.1 MPa. The petroleum in the Fischer-Tropsch synthesis reaction water after the pretreatment is ≤5 mg / L, and the total oil is ≤20 mg / L.

[0103] Then, the pretreated Fischer-Tropsch synthesis reaction water (102) is fed into a tank oxidation reactor (2) and alcohol-acid conversion is carried out in the presence of an oxidant (103) from an oxidant tank (3), and the reaction conditions are: reaction temperature 23°C, residence time 30 min, the selected oxidant (103) is Fenton reagent, and the total dissolved amount of Fenton reagent in the Fischer-Tropsch synthesis reaction water is 5000 mg / L. The conversion rate of alcohol organic matter into acid organic matter is 85.0%.

[0104] The Fischer-Tropsch synthesis reaction water (104) after dealcoholization is sent to an extraction tank (4) and extracted in the presence of an extractant (105) from an extractant regulating tank (5). The reaction conditions are: extraction at room temperature (25°C) and a mixing time of 30 minutes. The selected extractant (105) is a mixture of trialkylphosphine oxide and diluent n-octanol, the ratio of the extractant to the aqueous phase is 2:1, and the mass ratio of trialkylphosphine oxide to n-octanol is 1:10. The acid removal rate is 99.5%.

[0105] The deacidified Fischer-Tropsch synthesis reaction water (106) is sent to an ultrasonic device (7) to be subjected to cavitation deep treatment with an oxidant (110) from an oxidant tank (3), wherein the reaction conditions are: an operating temperature of 17° C., a reaction time of 170 min, a Fenton reagent as the selected oxidant (110), and a total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water of 20,000 mg / L. The purified Fischer-Tropsch synthesis reaction water (111) flowing out of the ultrasonic device (7) has a COD of ≤100 and a pH of 6.91.

[0106] The carboxylic acid-containing extract phase (108) is sent to a product recovery tower (6). The number of plates of the product recovery tower (6) is 55, the tower top temperature is 55° C., the tower bottom temperature is 125° C., and the pressure in the tower is 25 kPa. The regenerated extractant (107) flows out from the bottom of the product recovery tower (6), and the carboxylic acid product is distilled from the top of the product recovery tower (6). The mass fraction of the acid product is greater than 95%, wherein the purity of the acetic acid product is 96%, and the purity of the propionic acid product is 97%.

[0107] Table 1 Analysis results of main components of each stream in Example 1

[0108]

[0109] Table 2 Analysis results of main components of each stream in Example 2

[0110]

[0111] Table 3 Analysis results of main components of each stream in Example 3

[0112]

[0113] Table 4 Analysis results of main components of each stream in Example 4

[0114]

[0115] Comparative Example 1

[0116] The Fischer-Tropsch synthesis reaction water (101) to be treated is filtered to remove solids and then pumped into a coalescence oil removal device (1), wherein the conditions for oil removal / solid removal pretreatment are a temperature of 25°C and a pressure of 0.1MPa. The petroleum in the pretreated Fischer-Tropsch synthesis reaction water is ≤10mg / L, and the total oil is ≤30mg / L. The deoiled Fischer-Tropsch synthesis reaction water directly enters a cyclone / Venturi cavitator (7) to be synergistically oxidized with the oxidant (110) ozone from the oxidant tank (3). The total dissolved amount of ozone in the Fischer-Tropsch synthesis reaction water is 5000mg / L. The cavitation deep treatment is carried out under the following conditions: an operating temperature of 45°C and a reaction time of 50min. The COD in the purified Fischer-Tropsch synthesis reaction water (111) is Cr >>100, pH=2.82.

[0117] Table 5 Analysis results of main components of each stream in comparative example 1

[0118]

[0119] Comparative Example 2

[0120] The Fischer-Tropsch synthesis reaction water (101) is not deoiled and is directly pumped into the autoclave oxidation reactor (2), and alcohol-acid conversion is carried out in the presence of an oxidant (103) from an oxidant tank (3). The reaction conditions are 25° C. and a residence time of 30 min. The selected oxidant is ozone, and the total dissolved amount of ozone in the Fischer-Tropsch synthesis reaction water is 5000 mg / L. The conversion rate of alcohol organic matter into acid organic matter is 65%. The Fischer-Tropsch synthesis reaction water 104 after dealcoholization enters an extraction tower (4) for extraction, and the reaction conditions are: extraction at room temperature (25°C), mixing time 30 minutes, wherein the extractant is a mixture of tributyl phosphate, diluent n-octanol and kerosene, the ratio of the extractant to the aqueous phase is 2:1, and the acid removal rate is 99%; the Fischer-Tropsch synthesis reaction water (106) after deacidification enters a cyclone / Venturi type hydrodynamic cavitation device (7), and is subjected to cavitation deep treatment with an oxidant (110) from an oxidant tank (3), and the reaction conditions are: operating temperature 45°C, reaction time 240 minutes, the oxidant (110) is ozone, the total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is 20000 mg / L, and the COD content in the Fischer-Tropsch synthesis reaction water (111) after purification is 0.1%. Cr ≥100, pH=5.79. The acid-containing extract phase (108) enters the product recovery device (6), the product recovery tower has 55 plates, the top of the tower is 40°C-55°C, the bottom of the tower is 95°C, and the pressure is 25 kPa. The regenerated extractant (107) flows out from the bottom of the product recovery device (6), and the acid product (109) is distilled from the top of the product recovery device (6). The mass fraction of the acid product (109) is greater than 90%, wherein the purity of the acetic acid product is 91%, and the purity of the propionic acid product is 92%.

[0121] Table 6 Analysis results of main components of each stream in comparative example 2

[0122]

[0123] Comparative Example 3

[0124] The Fischer-Tropsch synthesis reaction water (101) to be treated is filtered to remove solids, and then pumped into the coalescence oil removal device (1) for oil removal, wherein the oil removal / solid removal pretreatment conditions are a temperature of 25°C and a pressure of 0.1MPa. The pretreated petroleum is ≤10mg / L, and the total oil is ≤30mg / L; then, the pretreated Fischer-Tropsch synthesis reaction water (102) is sent to the tank oxidation reactor (2), and alcohol-acid conversion is carried out in the presence of an oxidant (103) from an oxidant tank (3), and the reaction conditions are: reaction temperature 25°C, residence time 30min, oxidant (103) is ozone, and the total dissolved amount of ozone in the Fischer-Tropsch synthesis reaction water is 200mg / L, and the conversion rate of alcohol organic matter into acid organic matter is 50%;

[0125] The Fischer-Tropsch synthesis reaction water (104) after dealcoholization is sent to a four-stage centrifugal extractor (4) and extracted in the presence of an extractant (105) from an extractant regulating tank (5), wherein the reaction conditions are: extraction at room temperature (25°C) and a mixing time of 30 minutes, wherein the selected extractant (105) is a mixture of tributyl phosphate and diluents n-octanol and kerosene, the ratio of the extractant to the aqueous phase is 2:1, and the acid removal rate is 75%; the Fischer-Tropsch synthesis reaction water (106) after deacidification is sent to a cyclone-type cavitator (7) and subjected to cavitation deep treatment with an oxidant (110) from an oxidant tank (3), wherein the reaction conditions are: an operating temperature of 38°C and a reaction time of 240 minutes, wherein the selected oxidant (110) is ozone, and the total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is 200 mg / L, and the COD content in the purified Fischer-Tropsch synthesis reaction water (111) is 0.1%. Cr >>100, pH=4.88.

[0126] The acid-containing extraction phase (108) is sent to a product recovery device (6). The number of tower plates of the product recovery device (6) is 50, the tower top temperature is 55° C., the tower bottom temperature is 110° C., and the pressure in the tower is 25 kPa. The regenerated extractant (107) flows out from the bottom of the product recovery device (6), and the acid product (109) is distilled from the top of the product recovery device (6). The mass fraction of the acid product (109) is greater than 92%, wherein the purity of the acetic acid product is 93%, and the purity of the propionic acid product is 92%.

[0127] Table 7 Analysis results of main components of each stream in comparative example 3

[0128]

[0129] Comparative Example 1 is a direct oxidation treatment without alkyd conversion, which shows that the oxidation efficiency is reduced and a large amount of organic resources are lost; Comparative Example 2 is a direct oxidation treatment without oil removal, which shows that the alkyd conversion rate of the Fischer-Tropsch synthesis reaction water without oil removal is significantly reduced; Comparative Example 3 reduces the concentration of oxidant in the water during the alkyd conversion process and the cavitation deep treatment process, directly reducing the alkyd conversion rate and cavitation efficiency, resulting in reduced water treatment efficiency and effluent COD Cr The value is much greater than 100 mg / L.

Claims

1. A method for treating Fischer-Tropsch synthesis reaction water, the method include: (1) performing oil removal / solid removal pretreatment on the Fischer-Tropsch synthesis reaction water to be treated to separate waste oil and solid particles from the Fischer-Tropsch synthesis reaction water, thereby obtaining oil-removed / solid-removed Fischer-Tropsch synthesis reaction water, wherein in the oil-removed / solid-removed Fischer-Tropsch synthesis reaction water, petroleum is ≤10 mg / L and total oil is ≤30 mg / L; (2) performing alcohol-acid conversion on the Fischer-Tropsch synthesis reaction water after oil / solid removal, oxidizing the alcohol organic matter in the Fischer-Tropsch synthesis reaction water after oil / solid removal into acid organic matter in the presence of an oxidant to obtain dealcoholized Fischer-Tropsch synthesis reaction water; (3) extracting the dealcoholized Fischer-Tropsch synthesis reaction water in the presence of an extractant to remove the acidic organic matter therein to obtain deacidified Fischer-Tropsch synthesis reaction water, and purifying and / or separating and collecting the acid in the acid-containing extractant to obtain an acid product; (4) The deacidified Fischer-Tropsch synthesis reaction water is subjected to deep cavitation treatment in the presence of an oxidant, thereby obtaining purified Fischer-Tropsch synthesis reaction water.

2. The method according to claim 1, in, The petroleum in the Fischer-Tropsch synthesis reaction water to be treated is ≤100 mg / L, the total oil is ≤500 mg / L, and the pH is 2-4.

3. The method according to claim 1 or 2, in, The petroleum in the Fischer-Tropsch synthesis reaction water after oil / solid removal is ≤5mg / L, and the total oil is ≤20mg / L; or, the amount of solid particles in the Fischer-Tropsch synthesis reaction water after oil / solid removal is less than 1mg / L.

4. The method according to claim 1 or 2, in, In step (2), one or more of the following conditions are used: The device for the conversion of alcoholic acid is selected from a kettle type, a tower type or a tank type reactor; The oxidant is selected from one or more of the following: ozone, Fenton's reagent, hydrogen peroxide, sodium persulfate, peracetic acid, chlorine dioxide, potassium permanganate and potassium dichromate; The alcohol-acid conversion is carried out under the following conditions: the reaction time is 1-10 hours, the gas phase oxidant pressure is controlled at 0.1MPa-1MPa, or the liquid-solid oxidant pressure is normal pressure, and the reaction temperature is 10-60°C; or, The total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is controlled to be between 1000 mg / L and 20000 mg / L.

5. The method according to claim 4, in, The total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is controlled to be between 2000 mg / L and 20000 mg / L.

6. The method according to claim 4, in, The total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is controlled to be 5000 mg / L-20000 mg / L.

7. The method according to claim 4, in, The total dissolved amount of the oxidant in the Fischer-Tropsch synthesis reaction water is controlled to be between 2000 mg / L and 10000 mg / L.

8. The method according to claim 1 or 2, in, In step (3), one or more of the following conditions are used: The extraction reaction device is selected from one or more of the following: a multi-stage centrifugal extractor, an extraction tank and an extraction tower; The extractant is selected from trialkylamine, tributyl phosphate, trioctylamine, trialkylphosphine oxide, trioctylphosphine oxide, or any mixture thereof; or, The reaction conditions of the extraction are: extraction at room temperature and mixing time of 30 min-60 min.

9. The method according to claim 1 or 2, in, In step (3), the extractant is diluted with a diluent, and the diluent is selected from toluene, benzene, cyclohexane, kerosene, n-octanol, or any mixture thereof.

10. The method according to claim 9, in, In step (3), the mass ratio of the extractant to the diluent is 10:1 to 1:

10.

11. The method according to claim 10, in, In step (3), the mass ratio of the organic phase to the aqueous phase during the extraction process is 2:1 to 1:2, wherein the organic phase refers to the extractant or the extractant diluted with a diluent, and the aqueous phase refers to the Fischer-Tropsch synthesis reaction water after the alcohol-acid conversion.

12. The method according to claim 1 or 2, in, In step (3), the process also includes separating the extraction phase from the raffinate phase, wherein the acid-containing extractant is the extraction phase and the deacidified Fischer-Tropsch synthesis reaction water is the raffinate phase.

13. The method according to claim 12, in, The extract phase and the raffinate phase are separated by centrifugal separation, cyclone separation or sedimentation separation.

14. The method according to claim 1 or 2, in, In step (3), the recovery of the acidic organic matter from the extraction phase is carried out in an extraction tower.

15. The method of claim 14, in, The extraction tower has 40-60 plates, a top temperature of 40-120° C., a bottom temperature of 80-250° C., and a pressure in the tower of 10-50 kPa.

16. The method of claim 14, in, The extractant from which the acid has been removed is returned to step (3) for recycling.

17. The method according to claim 1 or 2, in, The amount of acidic organic matter in the Fischer-Tropsch synthesis reaction water after deacidification is 100 mg / L-1100 mg / L.

18. The method according to claim 1 or 2, in, In step (4), one or more of the following conditions are used: The oxidant used is the oxidant in step (2); The usage amount of the oxidant is 100-100000 mg / L; The cavitation deep treatment is carried out under the following conditions: operating temperature 15-50°C; reaction time 10-180min; or, The cavitation deep treatment device is selected from one or more of the following: a Venturi type hydraulic cavitation device, a cyclone type hydraulic cavitation device, a orifice type hydraulic cavitation device, and an ultrasonic cavitation device.

19. The method of claim 18, in, The conditions of the cavitation deep treatment include: an operating temperature of 20-40° C.; and / or a reaction time of 60-120 min.

20. A system for treating Fischer-Tropsch synthesis reaction water, in, The system is a system for implementing the method for treating Fischer-Tropsch synthesis reaction water as described in any one of claims 1 to 19, and the system comprises: an oil removal / solid removal pretreatment unit, an alcohol acid conversion unit, an extraction deacidification recovery unit, and a cavitation deep treatment unit.

21. The system of claim 20, in, The extraction deacidification recovery unit includes: an optional product recovery device.

22. The system of claim 21, in, The product recovery device is selected from one or more of the following: a multi-stage centrifugal extractor, an extraction tank and an extraction tower.

23. The system according to any one of claims 20 to 22, in, The system for treating water in the Fischer-Tropsch synthesis reaction further comprises: an oxidant tank for storing and providing the oxidant; an extractant regulating tank for storing and regulating the extractant; a buffer tank; and a delivery pump.

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