High-temperature thickened oil sewage desalination and recycling treatment process

Abstract

The present application belongs to the technical field of oilfield sewage treatment, and particularly relates to a high-temperature thickened oil sewage desalination and reuse treatment process. The process comprises the following steps: performing electroflocculation treatment on the high-temperature thickened oil sewage to remove suspended solids, part of oil and silicon in the thickened oil sewage; performing poly ceramic membrane filtration treatment on the electroflocculation effluent to remove colloids and organic matters in the thickened oil sewage and reduce the chemical oxygen demand; and performing capacitive / membrane capacitive desalination treatment on the electroflocculation effluent to realize desalination, and the water quality after desalination meets the requirement of steam injection boiler feed water. The method is reasonable, the process is simple, and the flow is short. The present application can complete desalination treatment without cooling pretreatment of the high-temperature thickened oil sewage, can meet the requirement of boiler feed water, and can maximize the retention of the temperature of the thickened oil sewage and reduce the fuel consumption of the steam injection boiler.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oilfield sewage treatment and relates to a high-temperature thickened oil sewage desalination and recycling treatment process. BACKGROUND

[0002] A large amount of surplus sewage is generated in the process of steam injection for heavy oil exploitation, and a large amount of fresh water resources are consumed by steam injection boilers. In order to solve the contradiction between the two, a large amount of research on the desalination and recycling treatment process of heavy oil sewage has been carried out at home and abroad. The methods currently used mainly include membrane method and thermal method.

[0003] The membrane desalination technology mainly includes reverse osmosis method, nanofiltration method, forward osmosis method, etc. At present, the reverse osmosis membrane method is the most widely used water desalination process, mainly because of its standardized membrane element design, stable product quality, good process system expansion, short construction period, high automation, stable water quality, and high desalination efficiency. However, its shortcomings are also very obvious, such as the need for strict pretreatment, high energy consumption (use of high-pressure pump, discharge of pressurized concentrated water), high pressure level of pipeline and equipment design, low water recovery rate, short membrane life, membrane pollution, discharge of a large amount of high-salt concentrated water, and discharge of regeneration chemicals. In addition, the membrane method generally uses biochemical method for pretreatment, which needs advanced cooling for high-temperature thickened oil sewage, and the energy consumption is high. The thermal method mainly includes multi-effect distillation (MED) desalination, multi-stage flash evaporation (MSF) desalination, and mechanical vapor compression (MVC), etc. The thermal method has unique advantages: simple and reliable equipment, large equipment capacity, less limitation of raw water concentration, low pretreatment requirement, and direct use of low-pressure steam, waste gas, and other low-cost heat energy. Its disadvantages are high energy consumption, large equipment investment, and problems of equipment and pipeline scaling and corrosion.

[0004] CN202110608111.0 discloses a sewage desalination device, a sewage desalination equipment, and a sewage desalination method. The sewage desalination device includes a desalination reactor with a plasma liquid, which can adsorb anions and cations in the sewage in the plasma liquid through a flow electrode capacitive deionization reaction; an electrode regeneration reactor connected with the desalination reactor, which can regenerate the plasma liquid through an electrode regeneration reaction to desorb the anions and cations into elution water; and an ion exchange structure separating the plasma liquid from the sewage and the elution water. The sewage desalination device can continuously produce, simultaneously perform anion and cation adsorption and desorption operations, has high efficiency, and can recycle the plasma liquid after desorption to effectively reduce the cost. The flow electrode capacitive deionization technology fully embodies the technical features of safety, low energy consumption, continuity, and stability, and solves the problems of high cost, low efficiency, and inability to be applied to industrial wastewater, municipal sewage, and other actual environmental treatment.

[0005] CN200810137178.5 discloses a sewage treatment process. The invention solves the problems of small membrane flux, membrane pollution, frequent membrane cleaning and high cost per ton of water in the prior art. The invention carries out sewage treatment in the following steps: pretreatment, microfiltration treatment, circulating ultrafiltration membrane advanced treatment and nanofiltration membrane desalination treatment. The invention can effectively improve the flux of ultrafiltration membrane and nanofiltration membrane and prolong the operation cycle thereof. The circulating ultrafiltration membrane equipment used can increase the clean water yield to more than 90% and the cleaning cycle to more than 14 days. The nanofiltration membrane equipment used can produce water at a rate of more than 50% and the cleaning cycle can reach more than 14 days. The desalinated sewage of the invention can be directly used for preparing polymer solution, and the solution viscosity is better than that of water under the same conditions, and can replace water for oil displacement.

[0006] CN201110353720.2 discloses a crude oil electric desalting and electric desalting sewage treatment method, which comprises the following contents: after crude oil is produced from an oil field, the oil is first subjected to oil-water separation pretreatment, and then subjected to deep electric desalting treatment in the oil field to reduce the water content in the crude oil to less than 0.2% by mass and the salt content to less than 10 mg / L, and then delivered to a refinery, and the refinery does not set up a crude oil electric desalting facility; the wastewater produced by deep electric desalting is treated by one of the following optional ways: (1) the wastewater produced by deep electric desalting is used for oil field water injection after removal of floating oil and suspended solids; (2) the wastewater produced by deep electric desalting is treated by an oxidation pond after removal of floating oil, and discharged after reaching the discharge standard. The method can effectively reduce the problems of wastewater treatment difficulty caused by electric desalting of crude oil.

[0007] However, the above process or method is not suitable for desalination of high-temperature heavy oil sewage, and therefore it is urgent to develop a desalination process suitable for the characteristics of high-temperature oil field sewage in view of the existing problems of desalination of high-temperature heavy oil sewage. SUMMARY

[0008] The present application provides a high-temperature heavy oil sewage desalination and reuse treatment process. The present application first carries out electric flocculation treatment on high-temperature heavy oil sewage to remove most of the oil, silicon and suspended solids therein; then carries out poly ceramic membrane filtration to remove colloids and reduce chemical oxygen demand, thereby ensuring stable operation of subsequent desalination treatment; and finally carries out capacitive / membrane capacitive desalination treatment to remove ions in water under the action of a direct current electric field, thereby producing fresh water for reuse in a steam injection boiler. The present application can complete desalination treatment without cooling pretreatment of high-temperature heavy oil sewage, thereby meeting the requirements of the boiler feed water while maximizing the retention of the temperature of the heavy oil sewage and reducing fuel consumption of the steam injection boiler.

[0009] The present application discloses a high-temperature heavy oil sewage desalination and reuse treatment process, which comprises the following steps:

[0010] (1) the high-temperature thickened oil sewage is treated by electroflocculation to remove suspended solids, part of oil and silicon in the thickened oil sewage;

[0011] (2) the electroflocculation effluent is treated by poly ceramic membrane filtration to remove colloid and organic matter in the thickened oil sewage and reduce the chemical oxygen demand;

[0012] (3) the electroflocculation effluent is treated by capacitive / membrane capacitive desalination to realize desalination, and the water quality after desalination meets the requirement of steam injection boiler feed water.

[0013] As a further scheme of the present application: the device used for the electroflocculation treatment in step (1) is provided with a gas dispersion device at the bottom, and air or ozone aeration can be carried out.

[0014] As a further scheme of the present application: the electrode used for the electroflocculation treatment in step (1) is a perforated aluminum electrode or a perforated iron electrode.

[0015] As a further scheme of the present application: the electroflocculation reaction condition in step (1) is that the current density is 10-18 mA / cm 2 , and the reaction time is 15-30 min.

[0016] As a further scheme of the present application: the electrode used for the capacitive / membrane capacitive desalination treatment in step (3) is a carbon matrix prepared by co-heat treating the electroflocculation float and cotton rods, and then titanium is loaded.

[0017] As a further scheme of the present application: the method for loading titanium is that: after the carbon matrix is ground and sieved, it is dissolved in sewage ethanol, Tween-80 or Span-10 is added and ultrasonic treatment is carried out for 5-10 min, a mixed solution of titanium isopropylate, anhydrous ethanol and hydrochloric acid is poured into the mixture, and stirring is carried out in a 40-60℃ water bath for 4-6 h, and then vacuum filtration and drying are carried out to obtain the electrode material used for capacitive / membrane capacitive desalination.

[0018] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0019] (1) the present application realizes effective removal of oil, suspended solids, organic matter, silicon and salt in high-temperature thickened oil sewage through the unit treatment processes of electroflocculation, poly ceramic membrane, capacitive / membrane capacitive, and the water quality after treatment meets the requirement of thickened oil thermal recovery steam injection boiler feed water, and the present application can be widely applied to high-temperature thickened oil sewage;

[0020] (2) the method of the present application is reasonable, the process is simple, and the flow is short;

[0021] (3) the present application can complete desalination treatment without cooling pretreatment of high-temperature thickened oil sewage, the boiler water requirement is met, the temperature of the thickened oil sewage is maximally reserved, and fuel consumption of the steam injection boiler is reduced;

[0022] (4) Each processing unit of the present invention is modularly combined and can be combined and switched according to needs.

[0023] (5) In this invention, the desalination electrode material of the capacitor / membrane capacitor is obtained by modifying the scum of the preceding treatment device, which reduces secondary pollution during the treatment process. Attached Figure Description

[0024] Figure 1 This is a flowchart of the high-temperature heavy oil wastewater desalination and reuse treatment process of the present invention;

[0025] Figure 2 XPS image of the electrode before titanium loading modification;

[0026] Figure 3 XPS image of the electrode after titanium loading modification;

[0027] Figure 4 The images show scanning electron microscope (SEM) images of the electrodes before and after titanium loading modification. Detailed Implementation

[0028] The method of the present invention will be described below with reference to the accompanying drawings and specific embodiments, so as to make the technical solution of the present invention easier to understand and master, but the present invention is not limited thereto.

[0029] like Figure 1 As shown, the present invention provides a high-temperature heavy oil wastewater desalination and reuse treatment process, the process comprising the following steps:

[0030] (1) High-temperature heavy oil wastewater is treated by electrocoagulation. Suspended solids, some petroleum and silicon in the heavy oil wastewater are removed by dissolution of the electrodes.

[0031] (2) Electrocoagulation effluent is filtered by polyceramic membrane. The polyceramic membrane is high temperature resistant, pollution resistant and has high efficiency in removing organic pollutants, thus removing colloids and organic matter from heavy oily wastewater and reducing chemical oxygen demand.

[0032] (3) Electrocoagulation effluent is subjected to capacitor / membrane capacitor desalination treatment. Under the action of electric field, the anions and cations in the heavy oil wastewater flow to the two electrodes and are adsorbed by the capacitor electrodes to achieve desalination. After desalination, the water quality meets the requirements of steam injection boiler feedwater.

[0033] The device used for electrocoagulation treatment in step (1) is equipped with a gas dispersion device at the bottom, which can perform air or ozone aeration.

[0034] The electrode used in the electrocoagulation treatment in step (1) is a perforated aluminum electrode or a perforated iron electrode.

[0035] The electrocoagulation reaction conditions described in step (1) are: current density 10⁻¹⁸ mA / cm². 2 The reaction time is 15-30 minutes.

[0036] The electrode used in the capacitive / film capacitive desalination treatment in step (3) is a carbon matrix prepared by co-thermal method with electric flocculation float and cotton rods, and then titanium is loaded.

[0037] The method for loading titanium is as follows: after grinding and screening the carbon matrix, the carbon matrix is dissolved in sewage ethanol, Tween-80 or Span-10 is added, and ultrasonic treatment is performed for 5-10 min, a mixed solution of isopropyl titanate, anhydrous ethanol and hydrochloric acid is poured into the mixture, stirring is performed in a 40-60℃ water bath for 4-6 h, and then vacuum filtration and drying are performed to obtain the electrode material used in capacitive / film capacitive desalination.

[0038] Example 1:

[0039] The thickened oil produced water from steam injection thermal recovery of oil field is taken as the treatment object, and the water quality is as follows: oil content 61.5 mg / L, suspended solids 298 mg / L, silicon 85 mg / L, salinity 15224 mg / L, and COD 890 mg / L. The following treatment is performed:

[0040] (1) Electric flocculation treatment

[0041] The current density is 11 mA / cm 2 , and the reaction time is 20 min. The main water quality indexes of the effluent are shown in Table 1.

[0042] Table 1 Water quality after electric flocculation treatment

[0043] Analytical item Value Analytical item Value Oil mg / L 11.2 Suspended matter mg / L 22.5 COD mg / L 680 Silica mg / L 8 Salinity mg / L 14556 Total hardness mg / L 845

[0044] (2) Poly ceramic membrane treatment

[0045] The operating pressure in the poly ceramic membrane treatment process is 0.35 MPa, and the poly ceramic membrane pore size is 5 nm. The main water quality indexes of the effluent are shown in Table 2.

[0046] Table 2 Water quality after poly ceramic membrane treatment

[0047] Analytical item Value Analytical item Value Oil mg / L 1.2 Suspended matter mg / L 1.9 COD mg / L 231 Silica mg / L 3.6 Salinity mg / L 13998 Total hardness mg / L 790

[0048] (3) Capacitive / film capacitive treatment

[0049] The voltage is 1.5 V, the electrode used is a self-made modified carbon electrode, and the main water quality indexes of the effluent are shown in Table 3.

[0050] Table 3 Water quality after capacitive / film capacitive treatment

[0051] Analytical item Value Analytical item Value Oil mg / L 0.5 Suspended matter mg / L 0.9 COD mg / L 212 Silica mg / L 3.3 Salinity mg / L 1232 Total hardness mg / L 223

[0052] The results show that after the electric flocculation-poly ceramic membrane filtration-capacitive / film capacitive treatment, the thickened oil produced water reaches the water quality requirement of the thickened oil steam injection boiler feed water, and the resource recycling of the sewage is realized.

[0053] Example 2:

[0054] Titanium-loaded modification was performed on carbon materials prepared by co-heating electrocoagulated slag and cotton stalks. The specific method is as follows:

[0055] Activated carbon (AC), Tween T-80, anhydrous ethanol, and isopropyl titanate (TTIP) were used as the base materials for preparing modified carbon materials. TiO2 was loaded onto the surface of activated carbon via a sol-gel reaction. First, 500 ml of anhydrous ethanol was poured into a 1000 ml beaker. Then, 25 g of activated carbon was weighed and dispersed in 500 ml of anhydrous ethanol. Tween T-80 (0.1% wt) was added dropwise and ultrasonically dispersed for 5 minutes. In another 500 ml beaker, 250 ml of anhydrous ethanol and 50 ml of concentrated hydrochloric acid (36.5%) were added and stirred with a glass rod. 37.5 ml of isopropyl titanate was slowly poured into the 250 ml of anhydrous ethanol acidified with concentrated hydrochloric acid, and then slowly poured into the activated carbon slurry. The resulting mixture was heated and stirred in a water bath at 50 °C for 6 hours. To prevent acid fumes from leaking out when the concentrated hydrochloric acid was poured, the above pouring and stirring operations were carried out in a well-ventilated area. Subsequently, the liquid was removed using a vacuum filtration device, and the powder was washed with anhydrous ethanol to remove excess hydrochloric acid and isopropyl titanate. The resulting powder was then dried in an oven at 120°C for 4 hours.

[0056] Figure 2 and Figure 3 The images show XPS plots of the electrodes before and after titanium loading modification.

[0057] After activation, the oxygen content of the modified electrode material increased significantly compared to the oxygen content of the unmodified electrode material.

[0058] Figure 4 The images show scanning electron microscope (SEM) images of the electrodes before and after titanium loading modification.

[0059] A1-A3 represent modified electrode materials, while C1-C3 represent unmodified electrode materials. The surface of the modified electrode materials is rougher than that of the unmodified electrode materials, and the surface is covered with particles of different sizes and shapes. This indicates that the modified electrode materials have a larger specific surface area and active groups on their surface, namely TiO2 groups. These active groups can improve the hydrophilicity of the electrode materials, allowing them to come into contact with more ions within the same time frame, thus completing the ion transfer process more quickly and exhibiting a higher ion exchange rate.

[0060] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A high-temperature thickened oil wastewater desalination and reuse treatment process, characterized in that, The process comprises the following steps: (1) treating the high-temperature thick oil sewage by electroflocculation to remove suspended solids, part of the oil and silicon in the thick oil sewage; The electrocoagulation reaction conditions in step (1) are: current density 10-18 mA / cm 2 , reaction time 15-30 min; (2) treating the electroflocculation effluent by poly ceramic membrane filtration to remove colloid and organic matter in the thick oil sewage and reduce the chemical oxygen demand; (3) treating the poly ceramic membrane filtration effluent by capacitive / membrane capacitive desalination to realize desalination, and the water quality after desalination meets the requirements of steam injection boiler feed water; The electrode used in the capacitive / membrane capacitive desalination treatment in step (3) is a carbon matrix prepared by co-heating electroflocculation sludge and cotton rods, and then loaded with titanium; The method for loading titanium is as follows: after grinding and sieving the carbon matrix, the carbon matrix is dissolved in anhydrous ethanol, Tween-80 or Span-10 is added and ultrasonic treatment is performed for 5-10 min, a mixed solution of isopropyl titanate, anhydrous ethanol and hydrochloric acid is poured into the mixture, and stirring is performed in a 40-60℃ water bath for 4-6 h, and then vacuum filtration and drying are performed to obtain the electrode material used in capacitive / membrane capacitive desalination.

2. The high-temperature thickened oil wastewater desalination and reuse treatment process of claim 1, wherein, The device used in the electroflocculation treatment in step (1) is provided with a gas dispersion device at the bottom, and air or ozone aeration can be performed.

3. The high-temperature thickened oil wastewater desalination and reuse treatment process of claim 1, wherein, The electrode used in the electroflocculation treatment in step (1) is a perforated aluminum electrode or a perforated iron electrode.

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