CN109399756B

CN109399756B - Method and apparatus for desalting and dewatering oil-containing waste

Info

Publication number: CN109399756B
Application number: CN201710696947.4A
Authority: CN
Inventors: 赵锐; 李本高; 沈明欢; 袁清; 马欣; 曹晓磊; 杨宇宁
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-08-15
Filing date: 2017-08-15
Publication date: 2021-12-17
Anticipated expiration: 2037-08-15
Also published as: CN109399756A

Abstract

The invention relates to the field of dirty oil or oil sludge treatment, in particular to a desalting and dewatering method and device for oil-containing waste. The method for desalting and dehydrating the oily waste material comprises the following steps: (1) in a closed system, carrying out microwave heating on the oily waste to obtain a superheated material; (2) depressurizing the superheated material to vaporize less than 60 wt% of the water in the oily waste to obtain vaporized steam and residual material; (3) and standing and layering the residual materials to obtain purified oil on the upper layer and salt-containing sewage on the lower layer. The desalting and dewatering method for the oily waste has the advantages of short settling time, good desalting and dewatering effect and stable desalting and dewatering effect.

Description

Method and apparatus for desalting and dewatering oil-containing waste

Technical Field

The invention relates to the field of dirty oil or oil sludge treatment, in particular to a desalting and dewatering method and device for oil-containing waste.

Background

Crude oil extraction, transportation and refining processes typically produce a quantity of contaminated oil and sludge of varying properties. In the oil field operation, the dirty oil and the oil sludge are mainly generated in each link of drilling operation, oil extraction process, gathering and transportation process, sewage treatment and the like, and along with the increase of the oil extraction difficulty, the yield of the associated dirty oil and oil sludge is increased, so that huge environmental protection pressure and economic pressure are formed for enterprises. In the crude oil refining process, the dirty oil and oil sludge are mainly generated in units such as an oil product tank area, crude oil electric desalting, a sewage oil separation tank and the like. The basic components of the dirty oil and the oil sludge are similar, the dirty oil and the oil sludge mainly comprise oil, silt, organic sludge, a surfactant, a large amount of water and the like, and the content of mechanical impurities such as the silt and the like in the dirty oil is low. They all have the characteristics of high content of colloid and asphaltene, various impurities, serious aging degree, strong emulsion stability and the like, and have great difficulty in desalting and dewatering treatment. The refinery generally mixes and smelts the dirty oil/fatlute and crude oil into the electric desalting device or directly sends the mixture into the coking device for treatment, but the mixing easily causes serious accumulation of an oil-water emulsifying layer of the electric desalting device, ultrahigh current tripping, and reduction of the desalting and dewatering qualification rate, and the stable operation of the device is influenced; the coking device usually has higher requirements on the water-containing salt content of the dirty oil/oil sludge, and the treatment capacity is far less than the production capacity of the dirty oil. Therefore, the method solves the problems of desalting and dewatering of the dirty oil/oil sludge, and is the key for realizing the environmental protection treatment and resource recycling.

At present, the methods for desalting and dehydrating the sump oil/oil sludge, which are commonly adopted at home and abroad, mainly comprise a gravity settling method, an electric dehydration method, a centrifugal separation method, an ultrasonic demulsification method and the like, and a combined process of the methods. Practice proves that the oil-water mixed fluid has the best oil-water separation effect in static state or laminar flow, the gravity settling and advection type oil-water separation technology based on the oil-water mixed fluid is widely applied to industry, but the technology is long in time consumption, low in efficiency and large in equipment, needs to consume a large amount of steam for heat tracing, needs to be specially prepared according to oil products for matching with a demulsifier, and is poor in applicability. In order to improve the treatment efficiency, technologies such as centrifugal separation, cyclone and the like are developed, but the equipment investment is large at one time, a large amount of emulsified water is contained in the recovered oil due to strong turbulent flow, and the treatment effect is closely related to the density difference of oil cement in the raw materials and has poor stability. In recent years, new technologies such as ultrasonic waves and microwaves are used for strengthening demulsification, the ultrasonic technology has high requirements on ultrasonic parameter control, and once the properties of raw materials fluctuate, secondary emulsification is easily caused, but dehydration difficulty is increased. The microwave has the characteristic of high-efficiency internal heating, and because the heat transfer process does not exist, the heating directly acts on the water phase, the temperature rise is rapid and uniform, the condensation and coalescence among water drops can be effectively enhanced, and the method is a good substitute of the traditional heat sedimentation method. However, in practical application, single microwave demulsification efficiency is not high and natural layering is difficult (microwave demulsification-centrifugal separation of complex emulsion in the middle layer of an oil field settling tank, proceedings of process engineering, 2007, 7(2), 258-.

CN102452776A discloses a method for treating oil sludge, which comprises pretreating oil sludge by microwave to break emulsion and dewater, then heating to higher temperature and entering into a flash tank for flash evaporation, and it can be seen that in the method, the microwave treatment is used as pretreatment of the flash evaporation process, the total dewatering rate is not high, and the method causes a large amount of salt to remain.

Disclosure of Invention

The invention aims to provide a method and a device for desalting and dehydrating oily waste, which have the advantages of short settling time, good desalting and dehydrating effect and stable desalting and dehydrating effect, aiming at the defects of low efficiency, poor desalting and dehydrating effect, easy influence of raw material properties on the desalting and dehydrating effect and the like of the conventional dirty oil/oil sludge desalting and dehydrating method.

In order to accomplish the above object, the present invention provides, in one aspect, a method for desalting and dewatering an oil-containing waste material, the method comprising:

(1) in a closed system, carrying out microwave heating on the oily waste to obtain a superheated material; the oily waste is dirty oil and/or oil sludge;

(2) depressurizing the superheated material to vaporize less than 60 wt% of the water in the oily waste to obtain vaporized steam and residual material;

(3) and standing and layering the residual materials to obtain purified oil on the upper layer and salt-containing sewage on the lower layer.

In a second aspect, the present invention provides an apparatus for desalting and dehydrating an oily waste material, comprising: drain tank, microwave generator and relief pressure valve, wherein:

the dehydration tank is arranged to be used for desalting and dehydrating the oily waste to provide a closable system and a stewing system;

the microwave generator is arranged for carrying out microwave heating on the oil-containing waste in the closed dehydration tank to obtain a superheated material;

the pressure reducing valve is arranged to perform pressure reduction treatment on the dehydration tank heated by the microwave so as to partially vaporize water in the oily waste.

The present invention provides in a third aspect a method for desalting and dewatering oily waste material using the above desalting and dewatering apparatus, wherein the method comprises:

1) in a closed system provided by a dehydration tank, carrying out microwave heating on the oily waste by microwaves provided by a microwave generator to obtain a superheated material; the oily waste is dirty oil and/or oil sludge;

2) opening a pressure reducing valve, and carrying out pressure reduction treatment on the superheated material to vaporize water with the weight percent of 60% or less in the oily waste to obtain vaporized steam and residual material;

3) and continuously standing and layering the residual materials in a dehydration tank to obtain purified oil on the upper layer and salt-containing sewage on the lower layer.

The desalting and dewatering method and the device for the oily waste have the following advantages:

(1) the influence of the property of the oily waste is small, the application range is wide, and the treatment effect is stable;

(2) the microwave heating process is not influenced by heat transfer efficiency and heat transfer speed, does not need reinforced heat transfer modes such as stirring and the like, is rapid and uniform in temperature rise, high in oil-water separation efficiency and good in effect, and has a good desalting effect;

(3) the material is operated in a static state, so that the problem of secondary emulsification caused by turbulent flow is avoided;

(4) the treatment efficiency is high, the operation is carried out at low temperature and low pressure, and the safety is strong;

(5) the device is compact, occupies small area, is simple to operate and control, and is easy for industrial application.

Drawings

FIG. 1 is a schematic view of a desalination and dehydration apparatus according to a preferred embodiment of the present invention.

Description of the reference numerals

1-a dehydration tank; 2-microwave generator; 3-a flow stabilizing component; 4-water collecting bag;

5-purifying the oil storage tank; 6-light component reflux tank; 7-condenser; 8-pressure reducing valve;

9-oily waste import; 10-a sludge discharge port; 11-saline sewage outlet;

12-outlet for condensed water.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In one aspect, the present invention provides a method for desalting and dehydrating an oil-containing waste material, the method comprising:

According to the invention, the material is statically heated to a slightly overheated state by microwaves, and the temperature of the material is quickly reduced to be below the boiling point temperature of water by depressurization treatment due to vaporization of part of water and light components in oil, so that most of water is reserved in the material. By utilizing the violent phase change, a stable oil-water emulsification interface can be destroyed, high-efficiency emulsion breaking is realized, the treated oil and water can be settled and layered in a short time to obtain an oil phase and a salt-containing water phase, and the high-efficiency dewatering, desalting and oil collecting effects are realized.

According to the present invention, the oily waste material may be any effluent oil and/or sludge to be treated containing brine as is conventional in the art, and the source of the effluent oil is, for example, one or more of effluent oil produced in an oil field exploitation gathering process, aging oil produced in the oil field exploitation gathering process, effluent oil produced in a refinery processing process, and the like; the oil sludge can be one or more of oil sludge settled at the bottom of a crude oil storage tank, oil sludge generated in oil field exploitation and gathering processes, and oil sludge generated in refinery storage and transportation, sewage treatment and other processes.

Wherein the oily waste contains a certain water content, salt content and mechanical impurity content, and the mechanical impurity can be inorganic particles such as silt. In the case where the oily waste is dirty oil, the composition thereof may be, for example: the water content is 10-70 wt% (e.g. 20-60 wt%, 25-50 wt%, 30-45 wt%), the salt content (calculated as NaCl) is 200-50000mg/L (e.g. 300-20000mg/L, 350-10000mg/L, 400-5000mg/L, 450-1000mg/L, 500-800mg/L), the mechanical impurity content is 0.1-5 wt% (e.g. 1-4 wt%), and the balance is oil content. In the case where the oily waste is sludge, the composition thereof may be, for example: the water content is 10-60 wt% (e.g. 20-55 wt%, 25-50 wt%, 30-45 wt%), the salt content (calculated as NaCl) is 400-.

According to the present invention, in the step (1), the oily waste is heated by microwave to form a superheated material, which means a material having a higher temperature than the boiling point of water in the atmospheric pressure or reduced pressure system, and the temperature of the superheated material of the present invention is slightly higher than the boiling point of water in the atmospheric pressure or reduced pressure system. The microwave heating only enables the temperature of the oily waste to slightly exceed the boiling point of water, so that flash evaporation is avoided in the pressure reduction process. For this reason, preferably, in the step (1), the microwave heating is performed such that the temperature of the obtained superheated material is 100-.

According to the present invention, it is preferable that the microwave heating conditions include: the radiation frequency is 300MHz-300GHz, and the power is 5-3000W. More preferably, the conditions of the microwave heating include: the radiation frequency is 1000MHz-3000MHz (for example 2450MHz), and the power is 800-1500W.

The microwave heating process is a static heating process, so that secondary emulsification caused by turbulent flow in the treatment process can be avoided, and oil-water stratification is facilitated.

According to the present invention, in the step (2), by subjecting the superheated material to depressurization treatment, vaporization can be caused by the temperature of the superheated material being higher than the boiling point of water under the reduced pressure due to the reduction of the system pressure, but this process only partially vaporizes the water in the oily waste and carries with it a portion of light oil, and the effect thereof is more mainly to promote demulsification and desalination. In the process, overheated water drops are instantaneously vaporized along with the reduction of pressure, a stable oil-water interface is damaged, water and part of light hydrocarbon components are vaporized into a heat absorption process, the temperature of residual materials is rapidly reduced to be lower than the boiling point of water at the overheating temperature, discrete water drops are mutually fused into a continuous water phase, oil-water layering is realized, and salt is washed into the water phase.

Wherein, although the depressurization treatment vaporizes 60 wt% or less of water in the oil-containing waste, that is, an increased desalination dehydration rate can be obtained, in order to obtain a higher desalination dehydration effect, the depressurization treatment preferably vaporizes 50 wt% or less of water in the oil-containing waste, preferably 30 wt% or less of water, more preferably 10 wt% or less of water, and still more preferably 5 to 8 wt% of water.

According to the present invention, it is preferable that the depressurization treatment is carried out so that the internal pressure of the closed system is reduced to 90 to 105kPa, preferably 100 to 102kPa, more preferably normal pressure (for example, may be an ambient atmospheric pressure, about 101.3kPa), while preferably satisfying the vaporization effect described above. Thus, the closed system after microwave heating may be subjected to only pressure release, or may be subjected to pressure release to a pressure slightly higher than normal pressure, or may be continuously evacuated to a pressure slightly lower than normal pressure, so long as the vaporization degree is preferably the above vaporization degree.

According to the invention, the above-mentioned depressurization not only vaporizes a portion of the water in the oily waste but also instantaneously lowers the temperature of the oily waste to a temperature below the boiling point of water, preferably to 60-90 c, more preferably to 70-85 c. And then the mixture is allowed to stand and delaminate at such a temperature. The time for this vaporization and temperature reduction process may be, for example, 1-10 seconds.

According to the present invention, preferably, in step (3), the conditions for standing stratification include: the temperature is 60-90 deg.C, and the time is 5-60 min. More preferably, the conditions for standing stratification comprise: the temperature is 70-85 deg.C, and the time is 10-30 min. In order to keep the temperature of the standing delamination not lower than the set delamination temperature, for example, the method can be realized by adopting a constant-temperature heat tracing manner of the shell of the equipment. According to the invention, through the treatment of the two steps, the standing layering time is greatly shortened, and the oil phase and the water phase of the oily waste can be well layered under the standing condition of the shortened time, so that the upper layer is purified oil, and the lower layer is salt-containing wastewater. The purified oil and the salt-containing wastewater can be respectively extracted according to the needs so as to finally realize the separation.

According to the present invention, it is preferable that the vaporized steam is subjected to condensation treatment to obtain condensed water and light oil, wherein the condensed water is a lower layer and the light oil is an upper layer.

The method can obtain higher dehydration rate and desalination rate in shorter standing and settling time, and preferably, the method ensures that the dehydration rate of the crude oil waste containing salt water is more than 95 percent and the desalination rate is more than 90 percent.

In a second aspect, the present invention provides an apparatus for desalting and dehydrating an oily waste material, comprising: dehydration jar 1, microwave generator 2 and relief pressure valve 8, wherein:

the dehydration tank 1 is arranged to provide a closable system and a static system for the desalination and dehydration of oily waste;

the microwave generator 2 is arranged for carrying out microwave heating on the oil-containing waste in the closed dehydration tank 1 to obtain a superheated material;

the pressure reducing valve 8 is configured to perform pressure reduction treatment on the dehydration tank 1 heated by the microwave so as to partially vaporize water in the oily waste.

As shown in FIG. 1, in order to match the above method of the present invention, the present invention provides a matched apparatus for desalting and dehydrating oily waste. The dehydration tank 1 is used for storing oily waste materials, and microwave heating (under a closed environment) and standing layering treatment are realized in the dehydration tank.

In order to be able to better avoid turbulence, it is preferred that a flow stabilizing member 3 is provided in the dewatering tank 1 and at the oily waste inlet 9 for settling silt in the portion of the oily waste and stabilizing the feed. The flow stabilizing member 3 is preferably in the form of a partition (for example, 1-3 partitions are provided), and a U-shaped flow passage is formed at the inlet of the dewatering tank. In order to remove silt, a silt discharging port 10 is arranged at the bottom of the flow channel and used for discharging large settled silt, and the opening degree of the silt discharging port is regulated and controlled by a silt discharging valve.

The configuration of the dewatering tank 1 is preferably horizontal, and in order to be able to better separate the saline sewage in the lower layer, it is preferable that the bottom of the dewatering tank 1 is constructed as a conical structure, and a water collecting bag structure 4 can be arranged at the end of the conical structure for storing the saline sewage in the lower layer obtained by still layering the vaporized residual materials in the dewatering tank 1, so that the saline sewage enters the water collecting bag 4 and can be discharged from a saline sewage outlet 11 at the bottom of the water collecting bag 4.

According to the invention, the dewatering tank 1 can also be provided with a purified oil storage tank 5 for storing upper layer purified oil obtained by standing and layering the vaporized residual material in the dewatering tank 1. This purified oil storage tank 5 is a device independent of the outside of the dehydration tank 1 except that the purified oil outlet of the dehydration tank 1 communicates with the inlet of the purified oil storage tank 5.

In order to collect the gas discharged during depressurization, it is preferable that the desalination and dehydration apparatus further comprises a light component reflux tank 6 and a condenser 7, wherein the condenser 7 is configured to condense the vapor of the partially vaporized light components in the oil-containing waste material after the depressurization treatment to obtain condensed water and light oil, and the light component reflux tank 6 is configured to store the condensed water and light oil obtained by the condensation treatment.

In order to facilitate control of the microwave heating, depressurization and the condensation process, it is preferable that the microwave generator 2 is disposed outside the dehydration tank 1, the light component reflux tank 6 is communicated with the vaporization vapor discharge port of the dehydration tank 1, the condenser 7 is communicated with the top outlet of the light component reflux tank 6, and the pressure reducing valve 8 is disposed at the gas outlet of the condenser 7. Therefore, the top evaporation steam outlet of the dehydration tank 1 is communicated with the lower steam inlet of the light component reflux tank 6, the top outlet of the light component reflux tank 6 is communicated with the steam inlet of the condenser 7, and the steam outlet of the condenser 7 is provided with a pressure reducing valve 8 to control the closed state of the whole system. The lower part of the light component reflux tank 6 is provided with a condensed water outlet 12 so as to discharge the condensed water of the lower layer, and the rest is the light oil of the upper layer.

In a third aspect, the present invention provides a method for desalting and dewatering oily waste material by using the above desalting and dewatering device, wherein the method comprises:

1) in a closed system provided by a dehydration tank 1, carrying out microwave heating on the oily waste by microwaves provided by a microwave generator 2 to obtain a superheated material; the oily waste is dirty oil and/or oil sludge;

2) opening a pressure reducing valve 8, and carrying out pressure reduction treatment on the superheated material to vaporize water with the weight of 60% or less in the oily waste to obtain vaporized steam and residual material;

3) and continuously standing and layering the residual materials in the dehydration tank 1 to obtain purified oil on the upper layer and salt-containing sewage on the lower layer.

The conditions and configuration of the method are the same as those of the desalting and dewatering method, and the adopted device is the same as that of the desalting and dewatering method, so that the invention is not repeated.

Under the cooperation of the device, the method is a batch method, namely, the oily waste in the next tank is treated after the oily waste in the dewatering tank is treated each time.

The present invention will be described in detail below by way of examples.

In the following examples:

the desalting and dewatering device for oily waste shown in FIG. 1 comprises a dewatering tank 1 of a horizontal structure, a microwave generator 2, a purified oil storage tank 5, a light component reflux tank 6, a condenser 7 and a pressure reducing valve 8; an oily waste inlet 9 is arranged on one side of the dehydration tank 1, two steady flow baffles 3 are arranged at the inlet 9 and in the dehydration tank 1 to provide a U-shaped flow channel, a conical structure is arranged below the U-shaped flow channel to store silt, and a sludge discharge port 10 is arranged at the tail end of the conical structure; the bottom of the dehydration tank 1 is also provided with a conical structure, the tail end of the conical structure is provided with a water collection bag 4, and the bottom of the water collection bag 4 is provided with a salt-containing sewage outlet 11; the microwave generator 2 is arranged outside the dewatering tank 1 to provide microwave radiation in the dewatering tank 1; an inlet of the purified oil storage tank 5 is communicated with a purified oil outlet at the lower part of the dehydration tank 1; the top evaporation steam outlet of the dehydration tank 1 is communicated with the steam inlet of the light component reflux tank 6, the steam outlet of the light component reflux tank 6 is communicated with the steam inlet of the condenser 7, and the steam outlet of the condenser 7 is provided with a pressure reducing valve 8 to regulate and control the closed state of the whole system.

The method for measuring the water content of the dirty oil or the sludge comprises the following steps: GB/T8929-2006.

The method for measuring the salt content of the dirty oil or the sludge comprises the following steps: SY/T0536-.

The dehydration rate was (1-water content of purified oil/water content of raw material) × 100%.

The salt rejection was (1-salt content of purified oil/salt content of raw material) × 100%.

Example 1

This example serves to illustrate the process for the desalination and dehydration of oily waste according to the invention.

By adopting the device shown in figure 1, dirty oil (water content is 37 wt%, salt content is 453mg NaCl/L, mechanical impurities is 3.3 wt%, and the balance is oil content) is pumped from an inlet 9 to the dehydration tank 1, enters the main body of the dehydration tank 1 through a U-shaped flow passage arranged at the inlet 9, then closing the pressure reducing valve 8 to keep the dehydration tank 1 in a closed state, opening the microwave reactor 2 to perform microwave heating (radiation frequency is 2450MHz and power is 1200W) on the dirty oil in the dehydration tank 1, stopping heating when the temperature of the dirty oil is stabilized to 130 ℃, and the pressure reducing valve 8 is opened after the pressure in the dehydration tank is stabilized to reduce the pressure in the dehydration tank 1 to the normal pressure (about 101.3kPa), and the condenser 7 is turned on to condense the vapor discharged from the dehydration tank 1, and the condensed components are collected by the light component reflux tank 6 (the condensed water collected in the light component reflux tank 6 accounts for 8% by weight of the water of the dirty oil); and (3) keeping the pressure reducing valve 8 in a pressure relief state, instantly relieving the pressure to enable the temperature of the residual materials in the dewatering tank 1 to reach 80 ℃, standing for 20min under the condition of keeping the temperature of 80 ℃, discharging salt-containing sewage from the bottom outlet 11 of the dewatering tank 1, and pumping the purified oil into the purified oil storage tank 5.

Wherein the water content of the obtained purified oil is 1.8 wt%, and the dehydration rate is 95.1%; the salt content is 43.8mg NaCl/L, and the salt rejection rate is 90.3%.

Example 2

The method of embodiment 1, except that:

the treated oily waste is oil tank bottom oil sludge with water content of 40.17 wt%, salt content of 714mg NaCl/L and mechanical impurity content of 14.8 wt%;

the conditions of microwave heating include: the radiation frequency is 2450MHz, and the power is 1500W;

microwave heating is carried out until the temperature of the oil sludge is 120 ℃, and condensed water collected in the decompressed light component reflux tank 6 accounts for 6 wt% of the water of the oil sludge;

the residual material in the dehydration tank 1 reaches 70 ℃ at the moment of pressure relief, and the dehydration tank is kept standing for 30min at the temperature of 70 ℃.

Wherein the water content of the obtained purified oil is 0.9 wt%, and the dehydration rate is 97.8%; the salt content is 36mg NaCl/L, and the salt rejection rate is 95%.

Example 3

The process of example 1 was followed except that the temperature of the contaminated oil was heated by microwave to 100 ℃ and the condensed water collected in the light fraction reflux drum 6 after depressurization accounted for 2% by weight of the contaminated water.

So that the water content of the purified oil thus obtained was 13.1% by weight and the dehydration rate was 64.6%; the salt content is 194mg NaCl/L, and the salt rejection rate is 57.2%.

Example 4

The process of example 1 was followed except that the temperature of the contaminated oil was heated by microwave to 150 ℃ and the condensed water collected in the light fraction reflux drum 6 after depressurization accounted for 52% by weight of the water content of the contaminated oil.

So that the water content of the purified oil obtained was 1.6% by weight and the dehydration rate was 95.7%; the salt content was 147mg NaCl/L, and the salt rejection was 67.6%.

Example 5

According to the method described in the example 1, except that the dewatering tank 1 is kept at 60 ℃ for standing and demixing for 20min after opening the pressure reducing valve to release pressure.

So that the water content of the purified oil obtained was 3.5% by weight and the dehydration rate was 90.6%; the salt content is 79.3mg NaCl/L, and the salt rejection rate is 82.5%.

Example 6

The procedure as described in example 1 was followed, except that the pressure was released and the mixture was kept at 80 ℃ for 5 min.

So that the water content of the purified oil obtained was 6.5% by weight and the dehydration rate was 82.4%; the salt content is 136.8mg NaCl/L, and the salt rejection rate is 69.8%.

Comparative example 1

The process of example 1 was followed except that the temperature of the contaminated oil was microwave heated to 240 ℃ and the condensed water collected in the light fraction reflux drum 6 after depressurization accounted for 90% by weight of the contaminated water.

So that the water content of the purified oil obtained was 0.8% by weight and the dehydration rate was 97.8%; the salt content is 430mg NaCl/L, and the salt rejection rate is 5%.

As can be seen from the above examples, the method of the present invention can obtain purified oil with excellent dehydration and desalination effects in a short time; particularly, the effect is more excellent under the preferable conditions of the present invention, wherein the dehydration rate can be, for example, 95% or more, and the salt removal rate can be, for example, 90% or more.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method for desalting and dewatering an oily waste material, comprising:

(3) standing and layering the residual materials to obtain purified oil on the upper layer and salt-containing sewage on the lower layer;

in the step (1), the microwave heating is carried out to ensure that the temperature of the obtained superheated material is 110-130 ℃;

in the step (3), the standing and layering conditions comprise: the temperature is 70-85 deg.C, and the time is 10-30 min;

when the oily waste is dirty oil, the composition of the oily waste is as follows: the water content is 10-70 wt%, the salt content (calculated by NaCl) is 200-50000mg/L, the mechanical impurity content is 0.1-5 wt%, and the balance is oil content; in the case where the oily waste is sludge, the composition thereof is: the water content is 10-60 wt%, the salt content (calculated by NaCl) is 400-80000mg/L, the mechanical impurity content is 5-60 wt%, and the balance is the oil content.

2. The method of claim 1, wherein the conditions of the microwave heating comprise: the radiation frequency is 300MHz-300GHz, and the power is 5-3000W.

3. The method of claim 1, wherein the depressurization treatment vaporizes less than 50 wt.% of the water in the oil-containing waste.

4. The method of claim 1, wherein the depressurization treatment vaporizes less than 30 wt.% of the water in the oil-containing waste.

5. The method of claim 1, wherein the depressurization treatment vaporizes less than 10 wt.% of the water in the oil-containing waste.

6. The method according to any one of claims 1 to 5, wherein the depressurization treatment is performed so that the internal pressure of the closed system is reduced to 90 to 105 kPa.

7. The method as claimed in any one of claims 1 to 5, wherein the depressurization treatment is carried out so that the internal pressure of the closed system is reduced to 102kPa 100.

8. The method according to any one of claims 1 to 5, wherein the depressurization treatment reduces the internal pressure of the closed system to normal pressure.

9. The method according to any one of claims 1 to 5, wherein the step (2) further comprises subjecting the vaporized steam to a condensation treatment to obtain condensed water and light oil.

10. The method according to any one of claims 1 to 5, wherein the method is such that the oily waste has a dehydration rate of 95% or more and a salt rejection rate of 90% or more.

11. The method according to any one of claims 1 to 5, wherein the de-salting and de-watering of the oily waste material is carried out in a de-salting and de-watering apparatus comprising: dehydration jar (1), microwave generator (2) and relief pressure valve (8), wherein:

the dehydration tank (1) is arranged to provide a closable system and a static system for the desalination and dehydration of oily waste;

the microwave generator (2) is arranged for carrying out microwave heating on the oil-containing waste in the closed dehydration tank (1) to obtain a superheated material;

the pressure reducing valve (8) is arranged to perform pressure reduction treatment on the dehydration tank (1) heated by microwave so as to partially vaporize water in the oily waste.

12. The method according to claim 11, wherein the desalination and dehydration apparatus further comprises a light component reflux tank (6) and a condenser (7), wherein the condenser (7) is used for condensing part of water vapor in the oil-containing waste material after the depressurization treatment to obtain condensed water and light oil, and the light component reflux tank (6) is used for storing the condensed water and light oil obtained by the condensation treatment.

13. The method according to claim 12, wherein the microwave generator (2) is arranged outside the dewatering tank (1), the light component return tank (6) is in communication with a boil-off vapour discharge of the dewatering tank (1), the condenser (7) is in communication with a top outlet of the light component return tank (6), and the pressure reducing valve (8) is arranged at a gas outlet of the condenser (7).

14. The method according to claim 11, wherein a flow stabilizing member (3) is arranged in the dewatering tank (1) and at the oily waste inlet (9) for settling silt in the oily waste and stabilizing the feed.

15. The method of claim 11, wherein the desalination and dehydration apparatus further comprises: a purified oil storage tank (5) and a water collection bag (4);

wherein the purified oil storage tank (5) is used for storing upper layer purified oil obtained by standing and layering the vaporized residual materials in the dehydration tank (1);

the water collecting bag (4) is used for storing the lower-layer salt-containing sewage obtained by standing and layering the vaporized residual materials in the dehydration tank (1).