CN113120984A - Oil-water mixture wastewater treatment method and system - Google Patents

Abstract

The invention relates to an oil-water mixture wastewater treatment method and system. The oil-water mixture wastewater treatment method comprises the following steps of preheating a raw oil-containing wastewater; evaporating, namely evaporating the preheated oily wastewater stock solution to obtain a concentrated solution, first liquid water and first steam; and a concentration step, concentrating the concentrated solution, and separating to obtain a discharge liquid, second liquid water and second steam. Under the above oil-water mixture wastewater treatment method, especially in the treatment process of oil-water mixture wastewater of diesel oil and engine oil, the oil-water separation effect is better. The oil-water mixture wastewater treatment system comprises a preheating system, an evaporation system and a concentration system, so that the oil-water mixture wastewater is separated.

Description

Oil-water mixture wastewater treatment method and system

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a system and a method for treating wastewater of an oil-water mixture.

Background

In the wastewater treatment process, different types of wastewater need to be treated in a specific way so as to effectively treat the different types of wastewater. At present, the method for treating the oil-water mixed wastewater generally adopts a coagulation-air floatation method for direct treatment.

The coagulation-air floatation method is that the oil-water mixed waste water is added with coagulant to produce coagulation reaction and produce more flocs, and then the waste water is subjected to air floatation process. In the air floatation process, fine bubbles are adhered to flocs in water, the flocs float up to the water surface along with the bubbles, and water is discharged from the bottom of the air floatation tank to finish the separation of water and oil.

However, the current coagulation-air flotation method has a good treatment effect on light oil when treating oil-water mixed wastewater. However, the treatment effect of the oil-water mixed wastewater of diesel oil and engine oil is not ideal.

Disclosure of Invention

Therefore, it is necessary to provide an oil-water mixture wastewater treatment method and system for solving the problem of poor oil-water separation effect in the conventional oil-water mixture wastewater treatment process of diesel oil and engine oil.

An oil-water mixture wastewater treatment method comprises the following steps:

preheating, namely preheating the stock solution of the oily wastewater;

evaporating, namely evaporating the preheated oily wastewater stock solution to obtain a concentrated solution, first liquid water and first steam;

a concentration step, concentrating the concentrated solution, and separating to obtain a discharge liquid, second liquid water and second steam; the concentration step adopts single-evaporation concentration and concentration in a row.

In one embodiment, the evaporation step comprises more than one cyclic evaporation step, and in two adjacent cyclic evaporation steps, the evaporation temperature in the previous cyclic evaporation step is higher than the evaporation temperature in the next cyclic evaporation step.

In one embodiment, in the evaporation step, in two adjacent cyclic evaporation steps, the temperature difference between the first vapor discharged in the previous cyclic evaporation step and the temperature difference between the first vapor and the wastewater concentrated solution entering the next cyclic evaporation step is 10-15 ℃.

In one embodiment, after the evaporation step is completed, the mass of the concentrated solution after concentration is 1.5-3.0 times of the mass of the oil compound in the raw liquid of the oily wastewater.

In one embodiment, after the evaporation step is completed, the mass of the concentrated solution after concentration is 2 times of the mass of the oil compound in the raw liquid of the oily wastewater.

In one embodiment, in the concentration step, single evaporation concentration is performed by intermittent heating.

In one embodiment, the concentration step is carried out in an amount of 33 to 66%.

In one embodiment, the concentration step is performed in an amount of 50%.

In one embodiment, the method further comprises a cooling step for cooling the first water vapor generated by the evaporation step and/or the second water vapor generated by the concentration step.

According to the oil-water mixture wastewater treatment method, water and oil in the oil-water mixture stock solution can be well separated through the preheating step, the evaporation step and the concentration step, and oil and water can be well separated no matter the oil-water mixture wastewater of light oil or the oil-water mixture wastewater of diesel oil and engine oil. Compared with the traditional coagulation-air floatation method, the method has the advantages that the oil-water mixing and separating effect is good, so that the secondary separation caused by poor oil-water separating effect is reduced, and the separation cost is reduced. In addition, the oil-water mixture wastewater treatment method does not need to input other medicines, can reduce the cost of inputting medicines, and can fundamentally reduce the pollution to the environment caused by the input medicines. In addition, the obtained discharge liquid has higher concentration, and is convenient for centralized subsequent treatment.

An oil-water mixture wastewater treatment system comprises the following steps:

the preheating system is used for heating the oily wastewater stock solution;

an evaporation system for evaporating the heated stock solution to separate a concentrated solution, first liquid water and first water vapor;

and the liquid inlet of the concentration system is communicated with the liquid outlet of the evaporation system, and the concentration system is used for concentrating the concentrated solution to obtain a discharge liquid, second liquid water and second steam.

According to the oil-water mixture wastewater treatment system, the oily wastewater is heated by the preheating system to reach the approximate boiling point, and then the stock solution is input into the evaporation system to be evaporated. During evaporation, a large amount of the first water vapor in the stock solution is separated. The remaining oil phase in the concentrate was combined with a small amount of water. The concentrated solution was passed through a concentration device and then further concentrated. The oil and water in the concentrated solution can be well separated to obtain the effluent basically containing no water. Particularly, the treatment system can better separate the oil-water mixed wastewater of diesel oil and engine oil.

Drawings

FIG. 1 is a flow chart of a wastewater treatment method for oil-water mixture according to an embodiment of the present invention;

FIG. 2 is a flow chart of a wastewater treatment method for oil-water mixture according to another embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an oil-water mixture system according to an embodiment of the invention.

Description of the drawings: 100. a preheating system; 101. a heating member; 102. a liquid material delivery pump; 200. an evaporation system; 210. an evaporation module; 211. a separation device; 212. a reflux heating device; 213. a first power member; 300. a concentration system; 310. a concentration device; 320. a second power member; 400. a cooling system; 410. a first condensing unit; 411. a main condenser; 412. finally condensing; 420. a second condensing unit; 430. a vacuum pump; 440. a separation tank; 500. a distilled water collection system; 501. a storage member; 502. and a distilled water pump.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

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

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, fig. 1 is a flow chart illustrating a method for treating wastewater containing an oil-water mixture according to an embodiment of the present invention. The oil-water mixture wastewater treatment method comprises the following steps:

s10 preheating step, namely preheating the oily wastewater stock solution.

S20 evaporation step, evaporating the preheated oily wastewater stock solution to obtain a concentrated solution, first liquid water and first steam;

and S30, concentrating the concentrated solution, and separating to obtain a discharge liquid, second liquid water and second steam. Wherein, the concentration step adopts single-steaming concentration and concentration in a row.

The preheating step S10 may heat the raw oil-containing wastewater to a temperature close to the boiling point, so as to facilitate subsequent evaporation. In the evaporation process, since the boiling point of water is lower than that of the oil compound, a large amount of water is evaporated into the first water vapor in the evaporation process, and the oil compound is still a liquid substance. A portion of the first water vapor may condense to form first liquid water in this step. The first liquid water can be directly discharged or can be recycled. And after the water (the first steam and the first liquid water) in the oil-containing wastewater stock solution is separated, a concentrated solution can be obtained at the same time. The concentrated solution contains a large amount of the above oil-based compounds. The concentrated solution is further concentrated in the concentration step S30, and the remaining water in the concentrated solution is separated to form the second water vapor from the water in the concentrated solution. A portion of the second water vapor may condense in this step to form second liquid water. And further concentrating the concentrated solution to obtain a discharge solution, wherein the water content of the concentrated solution is substantially 0. The discharged liquid is basically all oil compounds, so that the separation of an oil-water mixture is effectively realized.

Specifically, in the preheating step S10, the preheating system 100 may be used to preheat the raw liquid of oily wastewater to a temperature of 94 ℃ or higher. Because the boiling points of the oil compounds in the raw liquid of the oily wastewater are far higher than 100 ℃, after the preheating system 100 preheats the raw liquid of the oily wastewater, the temperature of the raw liquid of the oily wastewater is close to the boiling point (100 ℃) of pure water. The preheating system 100 may employ a heating element 101 to heat the oil-containing wastewater stock. The heating means of the heating member 101 may be hot water heating, electric heating, steam heating, heat transfer oil circulation heating, far infrared heating, or the like. In some embodiments, hot water heating may be used for heating. The heating member 101 may be a plate heater.

In the evaporation step S20, the preheated oily wastewater stock solution is evaporated. In the evaporation process, most of water in the oily wastewater stock solution is evaporated to the outside to form first steam, and meanwhile, a concentrated solution with a high content of oil compounds is obtained. In the evaporation step S20, the obtained part of the first water vapor is cooled to form first liquid water. The first liquid water can be directly discharged or recycled.

In order to achieve the concentration factor in the evaporation step S20, more than one cyclic evaporation step may be employed. After the oily wastewater passes through the last circulation evaporation step, the mass of the concentrated solution after concentration is 1.5-3.0 times of the mass of the oil compound in the crude liquid of the oily wastewater, such as 1.5, 1.8, 2.0, 2.5, 2.8, 3.0 times, etc. In the evaporation step S20, most of the water may be separated from the oil compounds for the subsequent process steps.

In the evaporation step S20, the evaporation may preferably be performed by means of a multi-effect evaporation cycle. Each effective evaporation cycle corresponds to one of the above-mentioned cyclic evaporation steps. In two adjacent circulating evaporation steps, the evaporation temperature in the previous circulating evaporation step is higher than that in the next circulating evaporation step. The variation of the evaporation temperature can be achieved by adjusting the pressure in the different cyclic evaporation steps. In addition, in order to efficiently utilize heat, the first water vapor discharged in the last cyclic evaporation step can be used as a heating heat source in the next cyclic evaporation step. And in order to ensure the heating effect and facilitate the evaporation of the oily wastewater, the temperature difference between the temperature of the first vapor discharged in the last cyclic evaporation step and the temperature of the wastewater concentrated solution entering the next cyclic evaporation step is 10-15 ℃, such as 10, 11, 12, 13, 14, 15 ℃ and the like.

For example, in the primary wastewater treatment process, 100t of oil-water mixed wastewater of diesel oil and engine oil is co-treated. The oil content in the unseparated oil-water mixed wastewater of diesel oil and engine oil is 5%. When the oily wastewater is treated, after the preheating step S10 is completed, the evaporation step S20 includes three cyclic evaporation steps, i.e., a first cyclic evaporation step, a second cyclic evaporation step, and a third cyclic evaporation step.

Wherein, the temperature difference between the first vapor temperature discharged in the last circulation evaporation step and the temperature of the concentrated solution of the wastewater entering the next circulation evaporation step is set to be 10 ℃, and after the evaporation step S20 of the oily wastewater is completed, the mass of the concentrated solution after concentration is 2 times of the mass of the oil compounds in the original solution of the oily wastewater. I.e., the concentration rate was 90%. In the first cyclic evaporation step, the pressure was set at-0.01987 MPa and the evaporation temperature at 94 ℃. In the second circulation evaporation step, the pressure is set to-0.05397 MPa, and the evaporation temperature is set to 80 ℃. In the third circulation evaporation step, the pressure is set to-0.08141 MPa, and the evaporation temperature is set to 60 ℃. After the evaporation step S20 was completed, the amount of the concentrated solution obtained was about 10 t. In the subsequent concentration step S30, the concentrated liquid may be further concentrated so that the obtained effluent liquid contains substantially no moisture. The remaining water in the concentrate is removed as a second vapor or a second liquid (adjusted accordingly in fig. 2). It should be noted that the second liquid water is formed during the condensation of a portion of the second water vapor in the concentration device 310.

In the concentration step S30, the concentration may be performed by single evaporation concentration or by multiple evaporation concentrations. Because the water content in the concentrated solution is low, the concentration is preferably carried out by adopting a single-steaming concentration mode on the basis of reducing energy consumption and flexibly concentrating to prevent oil compounds from being mixed in the second steam due to overhigh evaporation temperature. In the concentration process, the heating mode can be intermittent heating. The heating time length can be adjusted according to actual conditions so as to change the concentration temperature. After passing through the concentration step S30, the concentration amount of the concentrated solution may be about 33-66%, such as 33.3%, 35%, 40%, 45%, 50%, 55%, 60%, 66%, etc. For example, when the evaporation step S20 is completed and the mass of the concentrated solution after concentration is 2 times the mass of the oil compound in the raw oil-containing wastewater, the concentration amount is about 50% in the concentration step S30, and thus a discharge liquid substantially free of moisture can be obtained.

The uncondensed first vapor obtained in the evaporation step S20 and the uncondensed second vapor obtained in the concentration step S30 may be subjected to a direct discharge treatment. But the waste of heat by direct discharge is large due to its high temperature. In some embodiments, it may be subjected to a cooling process by the cooling step S40.

As shown in fig. 2, the cooling step S40 may cool the first water vapor obtained in the evaporation step S20 and the second water vapor obtained in the concentration step S30 to obtain third liquid water. Here, the first water vapor and the second water vapor may be cooled separately to obtain the third liquid water. Alternatively, the first steam and the second steam may be first sent to the same pipeline, and then the cooling step S40 is performed to obtain the third liquid water. After the third liquid water is obtained by adopting the respective cooling method, the obtained third liquid water may be merged and then discharged or may be subsequently utilized, or may be discharged or may be subsequently utilized, respectively. The first liquid water obtained in the evaporation step S20, the second liquid water obtained in the concentration step S30, and the third liquid water obtained in the cooling step S40 may be collected and discharged or used subsequently, or may be discharged or used subsequently, respectively.

It should be noted that the temperatures of the first liquid water, the second liquid water and the third liquid water are all higher, and these parts of liquid water with higher temperatures can be used as the heat source of the preheating system 100 to preheat the raw liquid of the newly treated oily wastewater. The liquid water can be discharged or treated in other ways after being cooled.

In some embodiments, the obtained first liquid water, second liquid water, and third liquid water may be collected and input to the preheating system 100 as a heat source, and at the same time, the liquid water may be cooled for discharge or subsequent use. In practical applications, due to the limited field for treating the raw liquid of the oily wastewater, it may be possible to combine the first liquid water with the third liquid water obtained by cooling the first water vapor and inject the combined first liquid water and third liquid water into the preheating system 100 as a heat source due to the problem of piping. Meanwhile, the second liquid water is merged with third liquid water obtained by cooling the second vapor, and then injected into the preheating system 100 as a heat source.

In the process of treating the oily wastewater by the coagulation-air floatation method in the traditional process, firstly, a floccule part is decomposed. Secondly, in the coagulation process, the addition amount and the treatment efficiency of the flocculating agent cannot be directly calculated according to theory and are not easy to calculate. In addition, the operating personnel need adjust the flocculating agent ratio in time according to the actual waste water condition. In addition, although the coagulation-air flotation process is effective for removing light oil, when the waste water to be treated is oil-water mixed waste water of diesel oil and engine oil, the coagulation-air flotation process is not effective, that is, the oil-water separation effect is not effective, resulting in an increase in the subsequent treatment cost.

In the method for treating wastewater containing oil and water mixture of the present application, the preheating step S10, the evaporation step S20, the concentration step S30 and the cooling step S40 are employed to treat wastewater containing oil, and particularly, when treating wastewater containing oil and water mixture of diesel oil and engine oil, no floc is present. In the evaporation and concentration processes, the treatment efficiency can be obtained through calculation, and when the wastewater is discharged into the next system, the time cut-off point can be conveniently known. In addition, the water content of the discharged liquid obtained after the treatment of the system is basically 0, the oil content of the obtained water is low, the discharged liquid can be directly discharged or recycled, the oil-water separation effect is good, and the cost of treating the wastewater is low.

FIG. 3 is a schematic view showing the configuration of an oil-water mixture wastewater treatment system according to an embodiment of the present invention.

Wherein, referring to the legend, the directions of the solid arrows are the water vapor flow directions (including freshly produced high temperature water vapor, first water vapor, and second water vapor). The direction of the hollow arrow is the flowing direction of the oily wastewater (including the oily wastewater stock solution, the concentrated solution and the discharged solution). The directions of the double solid arrows are the flowing directions of the liquid water (including the first liquid water, the second liquid water and the third liquid water). The direction of the triangular arrow is the flow direction of the cooling water. A is an untreated oily wastewater inlet, B is a discharge liquid outlet, and C is a fresh high-temperature steam inlet; d1 is a first distilled water outlet; d2 is a second distilled water outlet; e1 is a first non-condensable gas outlet; e2 is a non-condensable gas second outlet; f1 is at the first cooling water inlet; f2 at the second cooling water inlet; g1 is the first cooling water outlet; g2 is a second cooling water outlet; h1 is at the first seal water inlet; h2 is at the second seal water inlet; j1 is a first sealed water outlet; j2 is the second sealed water outlet.

An embodiment of the present invention provides an oil-water mixture wastewater treatment system, as shown in fig. 3, including a preheating system 100, an evaporation system 200, a concentration system 300, and a cooling system 400. Wherein, the preheating step S10 may be implemented by the preheating system 100, the evaporating step S20 may be implemented by the evaporating system 200, the concentrating step S30 may be implemented by the concentrating system 300, and the cooling step S40 may be implemented by the cooling system 400.

The oily wastewater stock solution may be preheated by the preheating system 100 to a temperature approaching boiling point. So as to shorten the temperature rise time in the subsequent evaporation and concentration processes. The heated oily wastewater stock solution enters an evaporation system 200 for evaporation, so that most of water in the wastewater is evaporated to obtain first water vapor and first liquid water obtained by condensing part of the first water vapor, and a concentrated solution with high oil compound content is obtained. Here, it should be noted that: since the concentrate also contains a small amount of water, the concentrate is further concentrated by passing the concentrate through a concentration system 300 to obtain a discharge having a higher content of oil compounds. Meanwhile, the concentration system 300 converts the residual water remaining in the concentrated solution into the second water vapor and the second liquid water formed by condensing the second water vapor. The cooling system 400 is used for cooling the first vapor discharged from the evaporation system 200 and the second vapor discharged from the concentration system 300 to obtain the third liquid water. The oil compound content in the first liquid water, the second liquid water and the third liquid water obtained by the evaporation system 200, the concentration system 300 and the cooling system 400 is lower and is basically 0, and the emission standard can be achieved. Therefore, the liquid water obtained by the oil-water mixture wastewater treatment system can be directly discharged and can also be recycled.

To achieve the above-described function of preheating the oily wastewater stock solution by the preheating system 100, in some embodiments, the preheating system 100 includes a heating element 101. The heating member 101 has a feed end, a discharge end, a liquid inlet end, and a drain end. The oily wastewater stock solution enters the heating element 101 from the feeding end, is discharged from the discharging end after being heated, and enters the evaporation system 200 after being preheated. High-temperature liquid enters the heating element 101 from the liquid inlet end, and is discharged out of the heating element 101 from the water discharge end after heat exchange is completed. Here, it should be noted that the high-temperature liquid may be any one or more of first liquid water, second liquid water, third liquid water, or fresh hot water. The fresh hot water can be water which is heated by a boiler and has a temperature approximately reaching the boiling point. The heating member 101 may be a heat exchanger, and further, the heat exchanger may be a plate heat exchanger.

The plate heat exchanger can exchange heat between liquid water with higher temperature obtained by at least one of the cooling system 400, the concentration system 300 and the evaporation system 200 and oily wastewater stock solution with lower temperature, so that the temperature of the oily wastewater stock solution is raised to a temperature close to the boiling point of the oily wastewater stock solution. Meanwhile, the plate heat exchanger can further reduce the temperature of the liquid water, so that the heat in the liquid water can be recycled, and the heating cost is effectively reduced. In addition, the heating member 101 can also select other equipment that can heat the waste water stoste for use, for example adopt the equipment that heating methods such as electrical heating, steam heating, conduction oil circulation heating, far-infrared heating correspond.

The number of the heating members 101 may be more than one. To facilitate the delivery of the oily wastewater to the heating element 101, the preheating system 100 may also include a liquid delivery pump 102. The discharge port of the liquid material conveying pump 102 is connected with an output pipeline, and the outlet end of the output pipeline can be provided with a fork. The number of the fork is the same as that of the heating members 101, and corresponds to one another, that is, one fork is communicated with the feed end of one heating member 101. The discharge end of each heating element 101 can be communicated to the same output pipeline through a pipeline, and the output pipeline is communicated with the feed end of the evaporation system 200, so that the heated oily wastewater stock solution is input to the evaporation system 200.

In some embodiments, the vaporization system 200 may include a plurality of sequentially connected vaporization modules 210. The evaporation module 210 can evaporate and concentrate stage by stage to obtain a concentrated solution. Each evaporation module 210 includes a separation device 211, a reflux heating device 212, and a first power member 213.

The separation device 211 is configured to separate the concentrated solution from the first steam. The separation device 211 may be a separation chamber. The separation chamber has a first feed end, a second feed end, a discharge end, and a vapor discharge end. The first feed end is used to communicate with the discharge end of the pre-heating device or with the discharge end of the preceding evaporation module 210.

The first power member 213 may be a forced circulation pump. The forced circulation pump includes a liquid inlet end and a liquid outlet end, and the liquid inlet end of the forced circulation pump is communicated with the discharge end of the separation device 211, such as by a pipeline. The liquid discharge end of the forced circulation pump is connected with a liquid discharge pipe, and one side of the liquid discharge pipe, which is far away from the liquid discharge end, is provided with a fork, that is, the first power member 213 is provided with a discharge fork and a circulation fork through the liquid discharge pipe. The discharge fork is connected to the heating device and the circulation fork is connected to the feed end of the following evaporation module 210 or the feed end of the concentration device 310.

The reflux heating device 212 can heat the oil-containing stock solution, and when the first steam is selected as the heat source of the reflux heating device 212, the reflux heating device 212 obtains first liquid water in the heat exchange process. Namely, after the first steam heats the oil-containing wastewater stock solution, the temperature of the first steam is reduced, and the first steam is liquefied to form first liquid water. The reflow heating apparatus 212 may be a heater. The reflow heating apparatus 212 has a feed end, a discharge end, an inlet end, an outlet end, and an outlet end. The feed end of the reflux heater 212 communicates with the circulation fork of the first power member 213. The discharge end of the reflux heater 212 is in communication with the second feed end of the separation chamber. The inlet end of the reflux heating device 212 is used for introducing high-temperature steam. The high-temperature steam may be freshly produced high-temperature steam, or may be the first steam discharged from the steam discharge end of the separation device 211 in the previous evaporation module 210.

It should be noted here that the freshly produced high temperature steam refers to steam separated with a non-oil water mixture. Such as steam generated by a boiler, etc. When freshly produced high temperature steam is used, it may be introduced into the vaporization system 200 through the freshly produced high temperature steam inlet C. And the air outlet end of the reflux heating device 212 is used for discharging low-temperature steam after heat exchange. The water outlet end of the reflux heater 212 is used to discharge the first liquid water.

When a plurality of evaporation modules 210 are selected, the pressure in the evaporation modules 210 in two adjacent evaporation modules 210 can be adjusted to make the evaporation temperature in the former evaporation module 210 higher than the evaporation temperature in the latter evaporation module 210. In order to reduce heat loss, the first water vapor generated in the previous evaporation module 210 may be used as a heat source for heating the reflux of the subsequent evaporation module 210. In some embodiments, the temperature difference between the first vapor discharged from the previous evaporation module 210 and the concentrated wastewater entering the subsequent evaporation module 210 is 10-15 ℃.

For example, in one embodiment, the number of the evaporation modules 210 is three, and the number of the evaporation modules is the first evaporation module 210, the second evaporation module 210, and the third evaporation module 210. The temperature of the concentrate in the third evaporation module 210 is 60 deg.c, and the pressure in the separation device 211 is set to about-0.08141 MPa, so that the temperature of the first steam discharged from the second evaporation module 210 may be 70 deg.c, and according to the degree of heat loss, the temperature of the concentrate of the wastewater in the second evaporation module 210 is about 80 deg.c, and the pressure in the separation device 211 is set to about-0.05397 MPa. The temperature of the first steam discharged from the first evaporation module 210 may be about 90 ℃, the temperature of the wastewater concentrate in the first evaporation module 210 may be about 94 ℃ according to the degree of heat loss, and the pressure in the separation device 211 may be about-0.01987 MPa. In some embodiments, the heat source of the reflow heating apparatus 212 in the first evaporation module 210 may be the high temperature steam generated freshly, and the heat source of the reflow heating apparatus 212 in the remaining evaporation modules 210 may be the first steam generated by the previous evaporation module 210.

In addition, an ejector may be further provided in the evaporation module 210 to increase the utilization rate of the steam.

The concentration system 300 includes a concentration device 310 and a second power member 320. The concentration device 310 is configured to further concentrate the concentrated solution discharged from the evaporation system 200, so that the water content in the discharge solution after further concentration is substantially 0. The concentrator 310 has a feed inlet, a discharge outlet, a drain outlet, and an exhaust outlet.

Wherein, the feed inlet of the concentration device 310 is connected with the discharge end of the evaporation system 200, and the connection mode can be connected through a pipeline. The vent of the concentration system 300 is used to vent the second water vapor. The drain port of the thickening apparatus 310 is used to drain the second liquid water. The second liquid water is formed by condensation in the concentration device 310 without discharging the second vapor in the concentration device. The discharge port of the concentration device 310 is communicated with the second power member 320. The heating mode of the concentration device 310 may be steam heating, that is, the concentration device 310 is an evaporation kettle. The concentration device 310 is also provided with an air inlet for inputting high temperature water vapor. The high-temperature water vapor can be freshly produced high-temperature water vapor. The second power member 320 is used for driving the concentrated solution to be discharged from the oil-water mixture wastewater treatment system through the concentration device 310. The second power member 320 may be a concentrated liquid pump, i.e. a water inlet of the concentrated liquid pump is communicated with a discharge port of the concentration device 310, and a water outlet of the concentrated liquid pump may discharge the discharged liquid from a pipeline or store the discharged liquid for subsequent operation.

In some embodiments, the number of concentrating devices 310 is more than one. The concentrator devices 310 may be similarly connected in parallel, may be similarly connected in series, or may be a combination of similar series and parallel connections.

The foregoing "parallel-like connection" means: the inlet of each concentrator device 310 is in communication with the discharge end of the evaporation system 200. The water outlets of the concentration devices 310 are communicated. The discharge port of each concentration device 310 is communicated with the second power member 320.

The foregoing "series-like connection" means: the discharge port of the previous concentrating device 310 is communicated with the feed port of the next concentrating device 310, and the water discharge ports of the concentrating devices 310 are communicated.

The combination of "connection in series and parallel like" means that the two aforementioned connection methods can be combined, for example, one concentration device 310 is connected in series with two parallel concentration devices 310.

When the concentration process is carried out, the intermittent single-steaming concentration mode can be preferably adopted. That is, the above-mentioned parallel connection is adopted, and the concentrator 310 is heated discontinuously. In this way, substantially all of the remaining water in the concentrate is evaporated to form a second vapor and a second liquid water, and the intermittent single-evaporation concentration allows temperature control to prevent evaporation of the oil compounds in the effluent.

Since the first steam and the second steam are generated in both the evaporation system 200 and the concentration system 300, the two steams may be cooled by the cooling system 400 in order to lower the temperature of the two steams to obtain liquid water. The cooling system 400 includes a condensing device.

In some embodiments, the condensing device comprises more than one condenser. The condenser may obtain the third liquid water by introducing condensed water to lower the temperature of the high-temperature first steam and/or the second steam. The first steam and the second steam may be cooled by the same condensing device, or may be cooled by one condensing device.

In order to store the third liquid water, the oil-water mixture wastewater treatment system is further provided with a distilled water collection system 500, and the distilled water collection system 500 comprises a storage member 501 and a distilled water pump 502. The storage 501 may store liquid water.

It should be noted that the liquid water herein includes not only the third liquid water, but also the first liquid water and/or the second liquid water. That is, the storage 501 may store or partially store the liquid water obtained by the cooling system 400, the concentration system 300, and the evaporation system 200 at the same time.

The storage member 501 may be a distilled water storage tank. Further, it is possible to store liquid water obtained from different systems by providing a plurality of storage members 501, respectively. When the liquid water stored in the storage 501 is discharged, the storage 501 may be discharged by the distilled water pump 502. Alternatively, the liquid water may be supplied to the heat exchanger of the preheating device by the distilled water pump 502. Although the liquid water is liquid and the temperature is not as high as that of the steam, the temperature of the liquid water is higher than that of the oily wastewater stock solution, and the newly treated oily wastewater stock solution can be preheated by a heat exchange mode. In the storage 501, there may be some residual water vapor, and the residual water vapor may be returned to the cooling system 400 for recondensing to generate liquid water and returned to the storage 501.

In some embodiments, the first water vapor generated by the evaporation system 200 and the second water vapor generated by the concentration system 300 are simultaneously fed to the same condensing unit for cooling. In other embodiments, the number of the condensing units may be two, that is, the first condensing unit 410 and the second condensing unit 420.

The first condensing unit 410 is used for condensing the first water vapor discharged from the evaporation system 200. In the first condensing unit 410, the condensed water for cooling is introduced into the condenser through a first cooling water inlet F1 to condense the first water vapor, and is then discharged through a first condensed water outlet G1. The first water vapor is condensed to obtain a third cooling liquid. The second condensing unit 420 is used for condensing the second water vapor discharged from the condensing unit 310. In the second condensing unit 420, the cooling condensed water is introduced into the condenser through the second cooling water inlet F2 to condense the second water vapor, and is then discharged through the second condensed water outlet G2. The second water vapor is condensed to obtain a third cooling liquid.

Since the evaporation system 200 discharges a large amount of the first water vapor, the number of the condensation members in the first condensation device 410 may be two or more, such as the main condenser 411 and the final condenser 412. The first water vapor discharged from the evaporation system 200 enters the main condenser 411 and the final condenser 412 in sequence for condensation. The third liquid water obtained after the condensation of the main condenser 411 and the final condenser 412 can be discharged into the storage 501 at the same time for storage.

Since a part of non-condensable gas is generated in the evaporation device, the non-condensable gas can sequentially pass through the main condenser 411 and the final condenser 412 and then is discharged out of the first condensation device 410 from the final condenser 412, so that the influence of the non-condensable gas on the heat exchange effect of the heater is reduced. In the second condensing unit 420, since the second steam generated by the condensing system 300 is less, the condensing can be performed by using only one condensing member. Similarly, the second steam of the condensing system 300 contains a part of non-condensable gas, and the non-condensable gas may pass through a condenser and then be discharged out of the second condensing unit 420.

To facilitate the discharge of the non-condensable gases out of the cooling system 400, a vacuum pump 430 and a knock out pot 440 are provided at the end of the last condensing element. The vacuum pump 430 may discharge the non-condensable gas to the separation tank 440.

In order to allow the vacuum pump 430 to normally operate, the vacuum pump 430 may normally operate by introducing seal water. In the first condensing unit 410, seal water is introduced from a first seal water inlet H1 and discharged from a first seal water outlet J1. In the second condensing unit 420, seal water is introduced from a second seal water inlet H2 and discharged from a second seal water outlet J2.

The separator tank 440 may separate the non-condensable gases and discharge them. In the first condensing unit 410, the non-condensable gas is discharged from a non-condensable gas first outlet E1. In the second condensing unit 420, the non-condensable gas is discharged from the non-condensable gas second outlet E2.

Meanwhile, the first liquid water and the third liquid water formed by the first water vapor in the first condensing device 410 are merged in the same storage 501 and are delivered to one heat exchanger in the preheating device by the distilled water pump 502. The second liquid water is merged with the third liquid water formed by the second water vapor in the second condensing unit 420 in another storage 501 and is sent to another heat exchanger in the preheating unit by another distilled water pump 502.

In the above oil-water mixture wastewater treatment system:

the flow direction of the oily wastewater is as follows: the crude liquid of the oily wastewater enters a preheating system from an untreated oily wastewater inlet A. In the preheating system 100, the oily wastewater stock solution is pumped by a feed liquid delivery pump into the feed end of the heating element 101. After being preheated, the preheated water enters the separating device 211 of the first evaporation module 210 of the evaporation system 200 from the discharge end of the heating element 101, and then flows out to the first power element 213 from the discharge end of the separating device 211.

The oily wastewater can be separated into two parts from the first power part 213, wherein one part enters the reflux heating device 212 from the circulating fork, and enters the separating device 211 from the discharge end of the reflux heating device 212 and the second feed end of the separating device 211 for circulating separation. The other part enters the separation device 211 of the next evaporation module 210. Until the oil-containing wastewater stock solution flows out to the concentration system 300 from the discharge fork of the first power member 213 of the last evaporation module 210 to form a concentrated solution.

The concentrated solution is concentrated in the concentration device 310 and discharged to the second power member 320 through the discharge port to form a discharged solution, and then the discharged solution is discharged from the second power member 320 and discharged from the oil-water mixture wastewater treatment system through the discharge liquid outlet B.

The flow direction of the water in the oil-containing wastewater is as follows: the crude liquid of the oily wastewater enters a preheating system from an untreated oily wastewater inlet A. After preheating in the preheating system 100, it enters the evaporation system 200. In the evaporation module 210, most of the moisture is evaporated into the first water vapor at the separation device 211 and discharged to the reflow heating device 212 of the next evaporation module 210 as a heat source. In the reflux heater 212, part of the first vapor is liquefied to form first liquid water. The first liquid water may enter the storage 501 for storage. During the heat exchange process of the reflux heating device 212, the remaining first water vapor may be introduced into the first cooling system 410 for condensation to obtain a third liquid water. The third liquid water is stored in the storage 501.

The water remaining in the concentrated solution enters the concentration device 310 along with the concentrated solution, and is heated in the concentration device 310 to be evaporated into second water vapor, and part of the second water vapor is cooled in the concentration device 310 to be second liquid water. The second liquid water may enter the storage 501 for storage. The remaining second water vapor may be passed to cooling system 400 for condensation to obtain a third liquid water. The third liquid water is stored in the storage 501. The first liquid water, the second liquid water and the third liquid water in each storage 501 can all be discharged out of the oil-water mixture wastewater treatment system through the distilled water pump 502. Or pumped into the preheating system 100 by the distilled water pump 502, so as to exchange heat in each liquid water into the untreated raw oil-containing wastewater while further cooling each liquid water. The liquid water further cooled by the preheating system 100 may be discharged from the first distilled water outlet D1 and/or the second distilled water outlet D2.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The method for treating the oil-water mixture wastewater is characterized by comprising the following steps of:

preheating, namely preheating the stock solution of the oily wastewater;

evaporating, namely evaporating the preheated oily wastewater stock solution to obtain a concentrated solution, first liquid water and first steam;

a concentration step, concentrating the concentrated solution, and separating to obtain a discharge liquid, second liquid water and second steam; the concentration step adopts single-evaporation concentration and concentration in a row.

2. The method according to claim 1, wherein the evaporation step includes one or more cyclic evaporation steps, and an evaporation temperature in a preceding cyclic evaporation step is higher than an evaporation temperature in a subsequent cyclic evaporation step in two adjacent cyclic evaporation steps.

3. The method for treating wastewater containing an oil-water mixture as defined in claim 2, wherein in the evaporation step, the temperature difference between the first steam discharged in the previous evaporation step and the wastewater concentrate introduced into the next evaporation step in two adjacent evaporation steps is 10-15 ℃.

4. The method of claim 1, wherein the mass of the concentrated solution after the evaporation step is 1.5 to 3.0 times of the mass of the oil compound in the raw oil-containing wastewater.

5. The method of claim 1, wherein the mass of the concentrated solution after the evaporation step is 2 times of the mass of the oil-based compound in the raw oil-containing wastewater.

6. The method for treating wastewater containing an oil-water mixture as defined in claim 1, wherein the concentration step comprises single-evaporation concentration by intermittent heating.

7. The method for treating wastewater containing an oil-water mixture as defined in claim 1, wherein the concentration is carried out in an amount of 33 to 66%.

8. The method for treating wastewater containing an oil-water mixture according to claim 1, wherein the concentration is performed in an amount of 50%.

9. The method for treating wastewater containing an oil-water mixture as defined in claim 1, further comprising a cooling step for cooling the first steam generated in the evaporation step and/or the second steam generated in the concentration step.

10. An oil-water mixture wastewater treatment system is characterized by comprising the following steps:

the preheating system is used for heating the oily wastewater stock solution;

an evaporation system for evaporating the heated stock solution to separate a concentrated solution, first liquid water and first water vapor;

and the liquid inlet of the concentration system is communicated with the liquid outlet of the evaporation system, and the concentration system is used for concentrating the concentrated solution to obtain a discharge liquid, second liquid water and second steam.

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