CN116177776A - Treatment system and treatment method for naphthenic acid alkali slag wastewater - Google Patents

Abstract

The invention discloses a system and a method for treating naphthenic acid alkaline residue wastewater; the processing system includes: the first reactor is used for mixing and stirring alkaline residue wastewater, process water and excessive organic extractant under a heating condition to obtain a first mixed solution; and delivering the first mixed liquor to a first separation unit; the first separation unit is used for separating the first mixed liquid to obtain neutral oil and separated liquid; and sending the separated liquid to a second reactor; the second reactor is used for carrying out mixed reaction on sulfuric acid, an organic extractant and the separation liquid under the heating condition to obtain a second mixed liquid; and delivering the second mixed liquor to a second separation unit; the second separation unit is used for separating the second mixed solution to obtain naphthenic acid; therefore, based on the system, the naphthenic acid can be effectively extracted from the naphthenic acid-base slag wastewater under normal pressure, and the extraction purity of the naphthenic acid is improved, so that the naphthenic acid-base slag wastewater can be normally discharged.

Description

Treatment system and treatment method for naphthenic acid alkali slag wastewater

Technical Field

The invention belongs to the technical field of petroleum production, and particularly relates to a treatment system and a treatment method for naphthenic acid-base slag wastewater.

Background

Naphthenic acid is an acidic compound present in petroleum, and is also known as petroleum acid, a dark brown oily liquid. Naphthenic acid is a carboxyl derivative of cycloalkanes, has a special smell, is almost insoluble in water, and is easily soluble in petroleum ether, ethanol, benzene and hydrocarbons. The industrial upstream of naphthenic acid mainly extracts naphthenic acid from raw materials such as naphthalene or petroleum crude oil, and the industrial downstream of naphthenic acid mainly uses naphthenic acid to manufacture paint catalysts, wood preservatives, and the like. Because the price of raw materials upstream of the naphthenic acid industry is continuously increased, and the production technology for extracting the naphthenic acid is difficult, there are few enterprises for producing the naphthenic acid on a large scale in China. At present, since the naphthenic acid productivity of China is continuously improved, the naphthenic acid market is over-supplied, so that in order to promote the development of naphthenic acid, china actively encourages the development of downstream industries of the naphthenic acid, and accordingly the rapid development of the naphthenic acid industry is driven.

The naphthenic acid content in petroleum varies due to the nature, and fraction of petroleum. Typically, the amount of naphthenic acid in petroleum is about 1%, but also up to 2-3%. Since naphthenic acid is consistent with the corresponding crude oil product in terms of its molecular composition, boiling point range, and oil solubility, it is difficult to obtain naphthenic acid from petroleum using a general distillation method. However, since naphthenic acid exists in petroleum, refinery equipment is severely corroded, thereby affecting the open cycle of petroleum and further affecting the improvement of refinery benefits. If the petroleum product contains naphthenic acid, corrosion of oil-using equipment is caused, the use benefit of tens of millions of enterprises is affected, and corrosion loss which should not occur is caused.

In the prior art, in order to prevent naphthenic acid from corroding oil refining equipment, oil refineries usually utilize alkaline washing petroleum products, however, a large amount of alkaline residue wastewater is generated, and chemical oxygen demand (Chemical Oxygen Demand, abbreviated as COD), neutral oil, salt content and phenolic substances in the alkaline residue wastewater are all relatively high; if the alkaline residue wastewater is directly discharged into the environment, the environment is seriously polluted; if the alkaline residue wastewater is directly sent to a sewage treatment plant, the normal operation of the sewage treatment plant is seriously affected, and the alkaline residue wastewater is difficult to treat to reach the standard. And in this way, precious naphthenic acid becomes waste of refinery waste residues, and huge economic loss is caused. The problem of treatment of alkaline residue wastewater is common for refineries, so that the technology of recycling naphthenic acid from the alkaline residue wastewater in refineries is developed and utilized, which has very important economic, environmental and social significance and can also obtain obvious economic, environmental and social benefits.

Disclosure of Invention

The invention provides a treatment system and a treatment method for naphthenic acid and alkali slag wastewater, wherein the treatment system can effectively extract naphthenic acid from the naphthenic acid and alkali slag wastewater and improve the purity of the extracted naphthenic acid.

To achieve the above object, according to a first aspect of embodiments of the present application, there is provided a treatment system for naphthenic acid-base slag wastewater, the treatment system comprising: the first reactor is used for mixing and stirring alkaline residue wastewater, process water and excessive organic extractant under a heating condition to obtain a first mixed solution; and delivering the first mixed liquor to a first separation unit; the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities; the first separation unit is used for separating the first mixed liquid to obtain neutral oil and separated liquid; and sending the separated liquid to a second reactor; the second reactor is used for carrying out a mixing reaction on sulfuric acid, an organic extractant and the separation liquid under the heating condition to obtain a second mixed liquid; and delivering the second mixed liquor to a second separation unit; and the second separation unit is used for separating the second mixed liquid to obtain naphthenic acid.

To achieve the above object, there is also provided according to a second aspect of the embodiments of the present application, a method for treating naphthenic acid alkali slag wastewater, the method comprising: adding alkaline residue wastewater, process water and excessive organic extractant into a first reactor, and fully stirring at 45-65 ℃ to obtain a first mixed solution; then the first reactor conveys the first mixed liquor to a first phase separation tank; wherein the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities; the first phase separation tank carries out static phase separation on the first mixed solution for 8-15 hours at the temperature of 45-65 ℃ to obtain a first upper phase material and a first lower phase material; then the first phase separation tank sends the first lower phase material to a second rectifying tower, and sends the first upper phase material to a second reactor; the second rectifying tower carries out rectification separation on the first lower-phase material to obtain neutral oil and dichloromethane respectively; adding sulfuric acid and an organic extractant to the second reactor; then the sulfuric acid, the organic extractant and the first upper phase material react for 0.1 to 1 hour in the second reactor at the temperature of between 30 and 40 ℃ to obtain a second mixed solution; the second reactor then delivers the second mixed liquor to a second separation unit; and the second separation unit performs separation treatment on the second mixed liquid to obtain naphthenic acid.

Compared with the prior art, the embodiment of the invention provides a system and a method for treating naphthenic acid alkaline residue wastewater; the processing system includes: the first reactor is used for mixing and stirring alkaline residue wastewater, process water and excessive organic extractant under a heating condition to obtain a first mixed solution; and delivering the first mixed liquor to a first separation unit; the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities; the first separation unit is used for separating the first mixed liquid to obtain neutral oil and separated liquid; and sending the separated liquid to a second reactor; the second reactor is used for carrying out a mixing reaction on sulfuric acid, an organic extractant and the separation liquid under the heating condition to obtain a second mixed liquid; and delivering the second mixed liquor to a second separation unit; and the second separation unit is used for separating the second mixed liquid to obtain naphthenic acid. In the embodiment, the neutral oil in the alkaline residue wastewater is fully dissolved in an organic extractant through a first reactor, and then the neutral oil is separated from the first mixed solution by utilizing a first separation unit; then, displacing sodium naphthenate in the alkaline residue wastewater by sulfuric acid in a second reactor, and fully dissolving the displaced naphthenic acid into an organic extractant; finally separating naphthenic acid from the second mixed solution by using a second separation unit; therefore, based on the system, the naphthenic acid can be effectively extracted from the naphthenic acid-base slag wastewater under normal pressure, and the extraction purity of the naphthenic acid is improved, so that the naphthenic acid-base slag wastewater can be normally discharged.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter by way of example and not by way of limitation with reference to the accompanying drawings. The same reference numbers will be used throughout the drawings to refer to the same or like parts or portions. It will be appreciated by those skilled in the art that the drawings are not necessarily drawn to scale. In the accompanying drawings:

FIG. 1 is a schematic diagram of a system for treating naphthenic acid alkaline residue wastewater according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a system for treating naphthenic acid alkaline residue wastewater according to another embodiment of the present invention;

fig. 3 is a schematic flow chart of a method for treating naphthenic acid alkaline residue wastewater according to an embodiment of the invention.

Detailed Description

In order to make the objects, features and advantages of the present invention more comprehensible, the technical solutions according to the embodiments of the present invention will be clearly described in the following with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Fig. 1 is a schematic structural diagram of a system for treating naphthenic acid alkali slag wastewater according to an embodiment of the present invention.

A system for treating naphthenic acid alkaline residue wastewater, the system comprising: the first reactor is used for mixing and stirring alkaline residue wastewater, process water and excessive organic extractant under a heating condition to obtain a first mixed solution; and delivering the first mixed liquor to a first separation unit; the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities; the first separation unit is used for separating the first mixed liquid to obtain neutral oil and separated liquid; and sending the separated liquid to a second reactor; the second reactor is used for carrying out a mixing reaction on sulfuric acid, an organic extractant and the separation liquid under the heating condition to obtain a second mixed liquid; and delivering the second mixed liquor to a second separation unit; and the second separation unit is used for separating the second mixed liquid to obtain naphthenic acid.

Specifically, the mixed liquid in the first reactor is mixed and stirred under the heating condition, so that the neutral oil in the alkaline residue wastewater can be fully dissolved into the organic extractant, and the extraction of the neutral oil in the alkaline residue wastewater is facilitated. And the mixed solution in the second reactor is subjected to mixed reaction under the heating condition, so that the rapid reaction between sodium naphthenate and sulfuric acid is facilitated, and the generated naphthenic acid can be fully dissolved in the organic extractant.

Here, the first separation unit and the second separation unit are not limited at all as long as the neutral oil and the naphthenic acid can be obtained by separation treatment. For example: the naphthenic acid can be obtained by adopting a mode of phase separation and rectification separation.

In the embodiment, neutral oil is separated from alkaline residue wastewater by utilizing a first reactor and a first separation unit; then separating naphthenic acid from the alkaline residue wastewater by using a second reactor and a second separation unit; therefore, the naphthenic acid can be effectively extracted from the naphthenic acid-base slag wastewater under normal pressure, and the extraction purity of the naphthenic acid is improved, so that the naphthenic acid-base slag wastewater can be normally discharged. In addition, the embodiment adopts excessive organic extractant for extraction, thereby thoroughly separating neutral oil in the alkaline residue wastewater and further improving the purity of subsequent naphthenic acid extraction.

In a preferred embodiment, the first separation unit comprises a first phase separation tank and a second rectification column; the first phase separation tank is used for carrying out phase separation treatment on the first mixed liquid under the heating condition after receiving the first mixed liquid to obtain a first upper-phase material and a first lower-phase material; conveying the first lower phase material to the second rectifying tower and conveying the first upper phase material to the second reactor; and the second rectifying tower is used for rectifying and separating the first lower-phase material, and outputting an organic extractant from the top of the tower and neutral oil from the bottom of the tower. In the embodiment, the water phase and the organic extractant phase dissolved with neutral oil are fully separated through a first phase separation tank; and then separating the neutral oil and the organic extractant phase by a second rectifying tower, thereby respectively obtaining a neutral oil byproduct and the organic extractant.

In a preferred embodiment, the second separation unit comprises: a second phase separation tank, a first rectifying tower and a sub-separation unit; the second phase separation tank is used for carrying out phase separation treatment on the second mixed liquid after receiving the second mixed liquid to obtain a second upper-phase material and a second lower-phase material; conveying the second upper phase material to a separation unit, and conveying the second lower phase material to a first rectifying tower; the first rectifying tower is used for rectifying and separating the second lower-phase material, and outputting an organic extractant from the top of the tower and naphthenic acid from the bottom of the tower; the sub-separation unit is used for separating the second upper-phase material to obtain sodium sulfate wastewater and naphthenic acid. In the embodiment, the water phase dissolved with sodium sulfate and the organic extractant phase dissolved with naphthenic acid are subjected to full phase separation through the second phase separation tank; then separating the organic extractant from the naphthenic acid through a first rectifying tower to obtain a naphthenic acid product; finally, further extracting naphthenic acid through a sub-separation unit; therefore, the naphthenic acid in the alkaline residue wastewater can be effectively extracted, and the purity of the naphthenic acid extraction is improved.

In a preferred embodiment, the sub-separation unit comprises: an extraction column and a third rectification column; the extraction tower is used for countercurrent extraction of the organic extractant input from the tower top and the second upper-phase material input from the tower bottom; and conveying the extracted third upper-phase material to a third rectifying tower, and conveying the extracted third lower-phase material to a first rectifying tower; the third rectifying tower is used for rectifying and separating the third upper-phase material, and the top of the third rectifying tower outputs an organic extractant and the bottom of the third rectifying tower outputs sodium sulfate wastewater; the first rectifying tower is also used for rectifying and separating the third lower-phase material, and the top of the tower outputs an organic extractant and the bottom of the tower outputs naphthenic acid. According to the embodiment, the aqueous phase is subjected to multistage extraction by using the organic extractant, so that the recovery rate of naphthenic acid is ensured, and the extraction rate of naphthenic acid in alkaline residue wastewater is improved. The organic extractant is separated from the wastewater by the third rectifying tower, so that the organic content in the wastewater is reduced, the treated alkaline residue wastewater can be normally discharged, and the environmental pollution is reduced.

In a preferred embodiment, the sub-separation unit further comprises a first filter; the first filter is arranged in front of the extraction tower and is used for filtering the second upper phase material after receiving the second upper phase material output by the second phase separation tank and conveying the filtered first filtrate to the extraction tower. According to the method, impurities in the water phase are filtered through the first filter, and the filtered water phase is extracted again, so that the purity of naphthenic acid extraction is improved, and the discharge of alkaline residue wastewater is facilitated.

In a preferred embodiment, the sub-separation unit further comprises a second filter; the second filter is arranged in front of the first rectifying tower, and is used for carrying out filtering treatment on the second lower phase material and the third lower phase material after receiving the second lower phase material of the second phase separation tank and the third lower phase material of the extraction tower, and conveying the filtered second filtrate to the first rectifying tower. Therefore, impurities in the dichloromethane phase of the second phase separation tank and the extraction tower are filtered through the second filter, and the purity of naphthenic acid extraction is improved.

In a preferred embodiment, the organic extractant is methylene chloride, petroleum ether or dichloroethane.

The organic extractant obtained in this example of sulfuric acid can be recycled, so that only a small amount of lost organic extractant needs to be periodically replenished during system operation.

Fig. 3 is a schematic flow chart of a method for treating naphthenic acid alkaline residue wastewater according to an embodiment of the invention. The treatment method of the naphthenic acid alkali slag wastewater at least comprises the following steps:

s301, adding alkaline residue wastewater, process water and excessive organic extractant into a first reactor, and fully stirring at 45-65 ℃ to obtain a first mixed solution; then the first reactor conveys the first mixed solution to a first phase separation tank; wherein the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities;

s302, carrying out stationary phase separation on the first mixed solution for 8-15 hours by a first phase separation tank at the temperature of 45-65 ℃ to obtain a first upper-phase material and a first lower-phase material; then the first phase separation tank sends the first lower phase material to a second rectifying tower, and sends the first upper phase material to a second reactor;

s303, rectifying and separating the first lower-phase material by a second rectifying tower to obtain neutral oil and an organic extractant respectively;

s304, adding sulfuric acid and an organic extractant into the second reactor; then sulfuric acid, an organic extractant and the first upper phase material react for 0.1 to 1 hour in a second reactor at the temperature of between 30 and 40 ℃ to obtain a second mixed solution; the second reactor then delivers the second mixed liquor to a second separation unit;

s305, separating the second mixed solution by a second separating unit to obtain naphthenic acid.

In a preferred embodiment, the second separation unit comprises: a second phase separation tank, a first filter, a second filter, an extraction tower, a first rectifying tower and a third rectifying tower; the second separation unit performs separation treatment on the second mixed liquid to obtain naphthenic acid; comprising the following steps: the second reactor conveys the second mixed liquor to the second split-phase tank; then the second phase separation tank carries out phase separation treatment on the second mixed liquid to obtain a second upper phase material and a second lower phase material; the second phase separation tank then conveys the second upper phase material to a first filter and conveys the second lower phase material to a second filter; the first filter is used for filtering the second upper-phase material to obtain impurities and first filtrate respectively; the first filter then delivers the first filtrate to an extraction column; the extraction tower utilizes an organic extractant to reversely extract the first filtrate to obtain a third upper-phase material and a third lower-phase material; then the extraction tower conveys the third upper phase material to a third rectifying tower, and conveys the third lower phase material to a second filter; the third rectifying tower carries out rectifying separation on the third upper-phase material to obtain dichloromethane and sodium sulfate wastewater respectively; the second filter is used for filtering the second lower-phase material and the third lower-phase material to obtain impurities and second filtrate; then a second filter conveys the second filtrate to a first rectifying tower; and the first rectifying tower carries out rectifying separation on the second filtrate to obtain naphthenic acid.

Fig. 2 is a schematic structural diagram of a system for treating naphthenic acid alkaline residue wastewater according to another embodiment of the present invention.

A system for treating naphthenic acid alkali slag wastewater, at least comprising:

the first reactor is used for mixing and stirring alkaline residue wastewater, process water and excessive organic extractant under a heating condition to obtain a first mixed solution; and delivering the first mixed solution to a first phase separation tank; the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities;

the first phase separation tank is used for carrying out phase separation treatment on the first mixed liquid under the heating condition after receiving the first mixed liquid to obtain a first upper-phase material and a first lower-phase material; conveying the first lower phase material to the second rectifying tower; and delivering the first upper phase material to the second reactor;

the second rectifying tower is used for rectifying and separating the first lower-phase material, and outputting an organic extractant from the top of the tower and neutral oil from the bottom of the tower;

the second reactor is used for carrying out a mixing reaction on sulfuric acid, an organic extractant and the separation liquid under the heating condition to obtain a second mixed liquid; and delivering the second mixed liquor to a second phase separation tank;

the second phase separation tank is used for carrying out phase separation treatment on the second mixed liquid to obtain a second upper-phase material and a second lower-phase material; and delivering the second upper phase material to a first filter and delivering the second lower phase material to a second filter;

the first filter is used for filtering the second upper phase material and conveying the filtered first filtrate to the extraction tower. The extraction tower is used for countercurrent extraction of the organic extractant input from the tower top and the second upper-phase material input from the tower bottom; and conveying the extracted third upper phase material to a third rectifying tower, and conveying the extracted third lower phase material to a second filter;

the third rectifying tower is used for rectifying and separating the third upper-phase material, and the top of the third rectifying tower outputs an organic extractant and the bottom of the third rectifying tower outputs sodium sulfate wastewater;

and the second filter is used for filtering the second lower-phase material and the third lower-phase material and conveying the filtered second filtrate to the first rectifying tower.

The first rectifying tower is also used for rectifying and separating the second lower phase material and the third lower phase material, and the top of the tower outputs an organic extractant and the bottom of the tower outputs naphthenic acid.

Specifically, the input end of the first reactor is used for adding alkaline residue wastewater, process water and dichloromethane; the output end of the first reactor is connected with the first split-phase tank; the first output end of the first phase separation tank is connected with the first input end of the second reactor, and the second output end of the first phase separation tank is connected with the second rectifying tower; the second input end of the second reactor is used for adding an organic extractant and sulfuric acid; the output end of the second reactor is connected with the input end of the second phase separation tank; the first output end of the second split-phase tank is connected with the first filter, and the second output end of the second split-phase tank is connected with the first input end of the second filter; the first output end of the first filter is connected with the first input end of the extraction tower; the second output end of the first filter is used for discharging impurities; the second input end of the extraction tower is used for inputting an organic extractant; the first output end of the extraction tower is connected with the input end of the third rectifying tower, and the first output end of the third rectifying tower is used for discharging the organic extractant; the second output end of the third rectifying tower is used for discharging sodium sulfate wastewater; the second output end of the extraction tower is connected with the second input end of the second filter; the first output end of the second filter is used for discharging impurities; the second output end of the second filter is connected with the input end of the first rectifying tower, the first output end of the first rectifying tower is used for discharging naphthenic acid, and the second output end is used for discharging organic extractant.

For example: the treatment method of the naphthenic acid alkali slag wastewater at least comprises the following steps:

(1) 1000kg of caustic sludge wastewater (comprising 260.7kg of sodium naphthenate, 105kg of neutral oil, 604.3kg of water and 30kg of impurities), 1000kg of process water and 1000kg of methylene dichloride are respectively added into a first reactor; the temperature in the first reactor was controlled to 50℃and the reaction was stirred for 0.5 hour;

(2) Conveying a first mixed solution (containing 260.7kg of sodium naphthenate, 105kg of oil, 1604.3kg of water, 1000kg of methylene dichloride and 30kg of impurities) after the reaction of the first reactor to a first phase separation tank, controlling the temperature of the first phase separation tank to be 50 ℃, and standing for 12 hours to perform phase separation;

(3) Conveying a first lower-phase material (containing 105kg of oil and 781kg of dichloromethane) from a first phase separation tank to a second rectifying tower for rectifying and separating, wherein 781kg of dichloromethane extracted from the tower top is recycled, and 105kg of oil product extracted from the tower bottom is sold as a byproduct;

(4) Feeding a first upper phase material (comprising 260.7kg of sodium naphthenate, 1604.3kg of water, 219kg of methylene dichloride and 30kg of impurities) from a first phase separation tank, 500kg of methylene dichloride and 250kg of 30% dilute sulfuric acid by weight into a second reactor; then the temperature of the second reactor is kept at 35 ℃ for reaction for 0.5 hour; at this time, the sodium naphthenate is converted into naphthenic acid, the generated sodium sulfate is dissolved in the water phase, and the naphthenic acid is dissolved in methylene dichloride;

(5) The second mixed solution (comprising 227kg of naphthenic acid, 1779.4kg of water, 719kg of methylene dichloride, 108.6kg of sodium sulfate and 30kg of impurities) reacted by the second reactor is conveyed to a second phase separation tank for phase separation;

(6) Delivering a second upper phase discharge (comprising 28kg of naphthenic acid, 1779.4kg of water, 30kg of impurities and 108.6kg of sodium sulfate) from the second phase separation tank to the first filter, and beneficially removing part of the impurities;

(7) The discharged material (containing 28kg of naphthenic acid, 1779.4kg of water, 15kg of impurities and 108.6kg of sodium sulfate) from which part of impurities are removed through the first filter still contains a small amount of naphthenic acid, enters from the bottom of the extraction tower, and is subjected to extraction recovery through countercurrent contact with 500kg of methylene dichloride entering from the top of the extraction tower;

(8) The third upper phase material (1779.4 kg of water, 108.6kg of sodium sulfate and a small amount of dichloromethane 38 kg) which comes out of the top of the extraction tower enters from the middle of the third rectifying tower, and is extracted into 38kg of dichloromethane from the top of the third rectifying tower after rectifying and separating, so that the recycling is performed; 1888kg of wastewater containing sodium sulfate is arranged at the bottom of the tower, and sewage treatment is needed;

(9) Collecting a second lower phase material (comprising 199kg of naphthenic acid and 719kg of methylene dichloride) from a second phase separation tank and a third lower phase material (comprising 28kg of naphthenic acid, 462kg of methylene dichloride and 15kg of impurities) from the bottom of the extraction tower into a second filter to remove the impurities;

(10) The discharged material after removing impurities from the second filter enters from the middle part of the first rectifying tower, and is recovered to be 1181kg of dichloromethane from the top of the first rectifying tower after rectifying and separating for recycling; 227kg of naphthenic acid product is extracted from the bottom of the tower and can be sold.

The application uses 1000kg of alkaline residue waste liquid as a reference, and the materials used are as follows: 1000kg of alkaline residue wastewater; 2000kg of dichloromethane (which can be recycled); 250kg of 30% sulfuric acid; 1000kg of process water; the extracted materials were as follows: 227kg of naphthenic acid; 105kg of neutral oil; 1880kg of sodium sulfate wastewater; impurity: 30kg.

The naphthenic acid recovered by the treatment method is sampled and tested based on SH/T0530-92 standard of petrochemical industry of the people's republic of China, and the detection result data are shown in the following table 1:

TABLE 1 index of naphthenic acids based on the treatment method of the present application

The processing method of the embodiment adopts two-stage split phases; firstly, adopting a first-stage phase separation to carry out full phase separation on a water phase and a dichloromethane phase dissolved with neutral oil; then adopting a second-stage phase separation to carry out full phase separation on a water phase dissolved with sodium sulfate and a dichloromethane phase dissolved with naphthenic acid; thus, the naphthenic acid can be effectively extracted from the naphthenic acid alkaline residue wastewater, and the purity of the extracted naphthenic acid is improved.

The basic principles of the present application have been described above in connection with specific embodiments, however, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not limiting, and these advantages, benefits, effects, etc. are not to be considered as necessarily possessed by the various embodiments of the present application. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, as the application is not intended to be limited to the details disclosed herein as such.

The block diagrams of the devices, apparatuses, devices, systems referred to in this application are only illustrative examples and are not intended to require or imply that the connections, arrangements, configurations must be made in the manner shown in the block diagrams. As will be appreciated by one of skill in the art, the devices, apparatuses, devices, systems may be connected, arranged, configured in any manner. Words such as "including," "comprising," "having," and the like are words of openness and mean "including but not limited to," and are used interchangeably therewith. The terms "or" and "as used herein refer to and are used interchangeably with the term" and/or "unless the context clearly indicates otherwise. The term "such as" as used herein refers to, and is used interchangeably with, the phrase "such as, but not limited to.

It is also noted that in the apparatus, devices and methods of the present application, the components or steps may be disassembled and/or assembled. Such decomposition and/or recombination should be considered as equivalent to the present application.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the application to the form disclosed herein. Although a number of example aspects and embodiments have been discussed above, a person of ordinary skill in the art will recognize certain variations, modifications, alterations, additions, and subcombinations thereof.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A system for treating naphthenic acid alkaline residue wastewater, comprising:

the first reactor is used for mixing and stirring alkaline residue wastewater, process water and excessive organic extractant under a heating condition to obtain a first mixed solution; and delivering the first mixed liquor to a first separation unit; the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities;

the first separation unit is used for separating the first mixed liquid to obtain neutral oil and separated liquid; and sending the separated liquid to a second reactor;

the second reactor is used for carrying out a mixing reaction on sulfuric acid, an organic extractant and the separation liquid under the heating condition to obtain a second mixed liquid; and delivering the second mixed liquor to a second separation unit;

and the second separation unit is used for separating the second mixed liquid to obtain naphthenic acid.

2. The system of claim 1, wherein the first separation unit comprises a first phase separation tank and a second rectification column;

the first phase separation tank is used for carrying out phase separation treatment on the first mixed liquid under the heating condition after receiving the first mixed liquid to obtain a first upper-phase material and a first lower-phase material; and delivering the first lower phase material to the second rectifying column and delivering the first upper phase material to the second reactor;

and the second rectifying tower is used for rectifying and separating the first lower-phase material, and outputting an organic extractant from the top of the tower and neutral oil from the bottom of the tower.

3. The system of claim 1, wherein the second separation unit comprises: a second phase separation tank, a first rectifying tower and a sub-separation unit;

the second phase separation tank is used for carrying out phase separation treatment on the second mixed liquid after receiving the second mixed liquid to obtain a second upper-phase material and a second lower-phase material; conveying the second upper phase material to a sub-separation unit, and conveying the second lower phase material to a first rectifying tower;

the first rectifying tower is used for rectifying and separating the second lower-phase material, and outputting an organic extractant from the top of the tower and naphthenic acid from the bottom of the tower;

the sub-separation unit is used for separating the second upper-phase material to obtain sodium sulfate wastewater and naphthenic acid.

4. A system according to claim 3, wherein the sub-separation unit comprises: an extraction column and a third rectification column;

the extraction tower is used for countercurrent extraction of the organic extractant input from the tower top and the second upper-phase material input from the tower bottom; and conveying the extracted third upper phase material to a third rectifying tower, and conveying the extracted third lower phase material to a second filter;

the third rectifying tower is used for rectifying and separating the third upper-phase material, and the top of the third rectifying tower outputs an organic extractant and the bottom of the third rectifying tower outputs sodium sulfate wastewater;

the first rectifying tower is also used for rectifying and separating the third lower-phase material, and the top of the tower outputs an organic extractant and the bottom of the tower outputs naphthenic acid.

5. The system of claim 4, wherein the sub-separation unit further comprises a first filter;

the first filter is arranged in front of the extraction tower and is used for filtering the second upper phase material after receiving the second upper phase material output by the second phase separation tank and conveying the filtered first filtrate to the extraction tower.

6. The system of claim 4, wherein the sub-separation unit further comprises a second filter;

the second filter is arranged in front of the first rectifying tower, and is used for carrying out filtering treatment on the second lower phase material and the third lower phase material after receiving the second lower phase material of the second phase separation tank and the third lower phase material of the extraction tower, and conveying the filtered second filtrate to the first rectifying tower.

7. The system of claim 1, wherein the organic extractant is methylene chloride, neutral oil ether, or ethylene dichloride.

8. A method for treating naphthenic acid alkali slag wastewater is characterized in that,

adding alkaline residue wastewater, process water and excessive organic extractant into a first reactor, and fully stirring at 45-65 ℃ to obtain a first mixed solution; then the first reactor conveys the first mixed liquor to a first phase separation tank; wherein the alkaline residue wastewater at least comprises sodium naphthenate, neutral oil, water and impurities;

the first phase separation tank carries out static phase separation on the first mixed solution for 8-15 hours at the temperature of 45-65 ℃ to obtain a first upper phase material and a first lower phase material; then the first phase separation tank sends the first lower phase material to a second rectifying tower, and sends the first upper phase material to a second reactor;

the second rectifying tower carries out rectification separation on the first lower-phase material to obtain neutral oil and an organic extractant respectively;

adding sulfuric acid and an organic extractant to the second reactor; then the sulfuric acid, the organic extractant and the first upper phase material react for 0.1 to 1 hour in the second reactor at the temperature of between 30 and 40 ℃ to obtain a second mixed solution; the second reactor then delivers the second mixed liquor to a second separation unit;

and the second separation unit performs separation treatment on the second mixed liquid to obtain naphthenic acid.

9. The method of claim 8, wherein the second separation unit comprises: a second phase separation tank, a first filter, a second filter, an extraction tower, a first rectifying tower and a third rectifying tower; the second separation unit performs separation treatment on the second mixed liquid to obtain naphthenic acid; comprising the following steps:

the second reactor conveys the second mixed liquor to the second split-phase tank; then the second phase separation tank carries out phase separation treatment on the second mixed liquid to obtain a second upper phase material and a second lower phase material; the second phase separation tank then conveys the second upper phase material to a first filter and conveys the second lower phase material to a second filter;

the first filter is used for filtering the second upper-phase material to obtain impurities and first filtrate respectively; the first filter then delivers the first filtrate to an extraction column;

the extraction tower utilizes an organic extractant to reversely extract the first filtrate to obtain a third upper-phase material and a third lower-phase material; then the extraction tower conveys the third upper phase material to a third rectifying tower, and conveys the third lower phase material to a second filter;

the third rectifying tower carries out rectifying separation on the third upper-phase material to respectively obtain an organic extractant and sodium sulfate wastewater;

the second filter is used for filtering the second lower-phase material and the third lower-phase material to obtain impurities and second filtrate; then a second filter conveys the second filtrate to a first rectifying tower;

and the first rectifying tower carries out rectifying separation on the second filtrate to obtain naphthenic acid.

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