Dehydration process of emulsion

Abstract

The invention provides a variable field intensity electric field demulsification and dehydration process for a water-in-oil type emulsion, aiming at the problems of high energy consumption, high operation cost, secondary liquid drops and the like caused by the adoption of high field intensity and high voltage during electric field demulsification and dehydration of a W / O type emulsion with a complex structure and relatively high water content. The method comprises the following steps: removing mechanical impurities from a water-in-oil emulsion needing to be demulsified and dehydrated by using an oil pump through a filter, heating the water-in-oil emulsion to 20-30 DEG C in an oil heater, then feeding the water-in-oil emulsion into a pulsed electric field demulsification and dehydration device, and carrying out demulsification and dehydration treatment by using a pulsed electric field. According to the method, low-field-intensity efficient demulsification and dehydration are realized, secondary emulsification is avoided, the stability and reliability of the demulsification effect are improved, the process energy consumption and the operation cost are remarkably reduced, and the technical and economic advantages are very prominent.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil demulsification and dehydration technology, specifically relating to a process for demulsifying and dehydrating water-in-oil emulsions using a variable field electric field. Background Technology

[0002] With the increasing years of oilfield exploitation in my country, the dehydration and purification of crude oil emulsions has become a crucial issue of ongoing concern in the oil and gas extraction industry. Simultaneously, with the year-on-year growth in lubricant consumption in my country, the purification and regeneration of waste lubricating oil has become a critical challenge that the lubricant industry urgently needs to address. Among these challenges, the dehydration and purification of waste oil emulsions is the primary technical bottleneck to be overcome. Crude oil emulsions and waste oil emulsions are mostly complex water-in-oil (W / O) emulsions with high water content; rapid and efficient demulsification and dehydration have always been the most difficult and core challenge in the treatment of these types of emulsions.

[0003] Electric field demulsification and dehydration technology utilizes an electric field to promote the coalescence of dispersed phase droplets in oil-water emulsions, thereby achieving effective oil-water separation. It is an important method for dehydrating and purifying W / O type emulsions. Currently, this technology is widely used in the purification of crude oil emulsions with high water content and the regeneration of waste oil emulsions. To achieve better dehydration and purification effects, existing electric field demulsification and dehydration processes typically employ high voltage to obtain high field strength, thereby improving the dehydration efficiency of the emulsion. However, high field strength operation leads to a significant increase in energy consumption, operating costs, and equipment investment. More importantly, excessively high field strength not only results in high energy consumption and costs but also easily induces the generation of secondary droplets, causing electrodispersion, which deteriorates the demulsification effect and may even lead to demulsification and dehydration failure.

[0004] Given the above, how to achieve rapid and efficient demulsification and dehydration of W / O type emulsions under low electric field strength, thereby effectively reducing actual operating voltage, energy consumption, operating costs and equipment investment, has become a key focus and challenge in the current field of electric field demulsification and dehydration technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a variable field strength electric field demulsification and dehydration process for water-in-oil emulsions that are complex in structure and have a large water content, which leads to high energy consumption, high operating costs and secondary droplets due to the use of high field strength and high voltage during electric field demulsification and dehydration.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A dehydration process for an emulsion is characterized in that: the water-in-oil emulsion requiring demulsification and dehydration is filtered to remove mechanical impurities, then heated to 20°C to 30°C in an oil heater, and then enters a pulsed electric field demulsification and dehydration device for demulsification and dehydration using a pulsed electric field.

[0007] Furthermore, the pulsed electric field is generated by a square wave pulse from a pulsed power supply.

[0008] Furthermore, in the pulsed electric field, with the maximum electric field strength of 0.5 kV / cm as the initial value, run for 3 to 5 seconds and observe the pulse power supply current display. If the current is less than or equal to 0.03 mA, increase the maximum electric field strength by 0.1 kV / cm to 0.15 kV / cm and repeat the above steps until the current on the pulse power supply current display is greater than 0.03 mA. Then run for another 1 to 3 seconds at the current maximum electric field strength, and then reduce it by 45% to 55% before proceeding with the subsequent demulsification and dehydration treatment until the oil-water separation process is completed.

[0009] Furthermore, when the maximum electric field strength is less than or equal to 1.5 kV / cm, the frequency of the pulsed electric field is 50 Hz to 500 Hz.

[0010] Furthermore, when the maximum electric field strength is greater than 1.5 kV / cm, the frequency of the pulsed electric field is 500 Hz to 2500 Hz.

[0011] Furthermore, the pulsed electric field has a pulse duty cycle of 0.2 to 0.5.

[0012] Furthermore, the current displayed on the pulse power supply current indicator... I (mA), if the current is less than or equal to 0.03mA, then the maximum electric field strength will be increased by Δ. E (kV / cm) I and △ E Satisfy the following relationship: △ E =(-5 / 3)× I +0.15.

[0013] Furthermore, the operation time continues until the pulse power supply current display shows a current greater than 0.03mA, based on the maximum electric field strength at that point. t (seconds), then reduce it by a percentage. p After that, subsequent demulsification and dehydration processes are carried out until the oil-water separation process is completed. t and p The following relationship must be satisfied: p =45× t 0.1827 .

[0014] Furthermore, the pulsed electric field can be a uniform electric field or a non-uniform electric field.

[0015] Furthermore, the water-in-oil emulsion requiring demulsification and dehydration treatment has a water content of 5% to 30% (by mass) and a kinematic viscosity of less than 80 mmHg at 40°C. 2 / s.

[0016] Compared with the prior art, the present invention has the following significant advantages: This invention achieves efficient demulsification and dehydration at low electric field strength. Based on the effects of droplet chain formation, dual-level coalescence, electrophoretic coalescence, and the enhancement of local electric field strength, this invention rapidly and accurately identifies the critical electric field strength for droplet chain formation by gradually increasing the electric field strength. At this critical field strength, the electric field strength is rapidly reduced after droplet chain formation, thus achieving rapid and efficient demulsification and dehydration of W / O emulsions at low electric field strength. Compared to traditional high-field-strength demulsification processes, this invention significantly reduces energy consumption and operating costs, demonstrating significant technological and economic advantages.

[0017] This invention avoids the problem of secondary emulsification. By rapidly reducing the electric field strength after droplet chain formation, the entire demulsification and dehydration process is completed under low field strength conditions. This effectively avoids secondary emulsification problems such as secondary droplet generation and electrodispersion caused by continuous high field strength, significantly improving the stability and reliability of the demulsification effect. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a dehydration process for an emulsion according to the present invention.

[0019] 1- Oil pump, 2- Filter, 3- Oil heater, 4- Pulse power current display, 5- Pulse electric field demulsification and dehydration device Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] A schematic diagram of the dehydration process of an emulsion according to the present invention is shown below. Figure 1 As shown. The water-in-oil emulsion that needs to be demulsified and dehydrated is pumped by oil pump (1) and filtered by filter (2) to remove mechanical impurities. It is then heated to 20℃~30℃ by oil heater (3) and then enters the pulse electric field demulsification and dehydration device (5) for demulsification and dehydration using pulse electric field. The current value is observed and measured by pulse power current display (4).

[0022] Example 1 A substance with a water content of 15% (mass percentage) and a kinematic viscosity of 60 mmHg at 40°C.2 The W / O type waste lubricating oil emulsion, after being filtered to remove mechanical impurities, enters the oil heater and is heated to 25°C. Subsequently, the emulsion is sent to a pulsed electric field demulsification and dehydration device (such as...). Figure 1 As shown in the figure, a square wave pulse power supply was used. After the demulsification process began, it was run for 4 seconds with the maximum electric field strength of 0.5 kV / cm as the initial value. The pulse power supply current display was observed, and the current was measured. I =0.02mA (less than 0.03mA). According to the relationship Δ E =(-5 / 3)× I The +0.15 calculation increases the maximum electric field strength by 0.12 kV / cm, to 0.62 kV / cm. After running for another 4 seconds, the current is measured. I =0.04mA (greater than 0.03mA), at which point the critical field strength is 0.62kV / cm. Operating at this field strength... t =2 seconds, then according to the formula p =45× t 0.1827 Calculations showed that the electric field strength was reduced by approximately 50% to 0.31 kV / cm. Demulsification and dehydration continued under this low field strength until oil-water separation was complete. During this process, the pulse electric field frequency was set to 200 Hz during the maximum field strength stage (0.62 kV / cm, less than 1.5 kV / cm) and 150 Hz during the low field strength stage (0.31 kV / cm), with a pulse duty cycle of 0.3. Finally, testing showed that the water content in the dehydrated oil was reduced to below 0.5%. The entire demulsification process was rapid and efficient, and no secondary emulsification phenomena such as electrodispersion were observed.

[0023] Example 2 A substance with a water content of 25% (mass percentage) and a kinematic viscosity of 45 mm at 40°C. 2 The crude oil emulsion, with a flow rate of / s, is filtered to remove mechanical impurities and then heated to 28°C in an oil heater. Subsequently, the emulsion is fed into a pulsed electric field demulsification and dehydration device using a square wave pulsed power supply. After the demulsification process begins, it is run for 3 seconds with an initial maximum electric field strength of 0.5 kV / cm, and the pulsed power supply current display is observed to measure the current. I =0.01mA. According to the relationship... △ E=(-5 / 3)× I The +0.15 calculation increases the maximum electric field strength by approximately 0.133 kV / cm, to 0.633 kV / cm. After running for another 3 seconds, the current was measured. I =0.035mA (greater than 0.03mA), at which point the critical field strength is 0.633kV / cm. Operate at this field strength. t =1.5 seconds, then according to the formula p =45×t 0.1827 Calculations showed a reduction of approximately 48%, lowering the electric field strength to approximately 0.34 kV / cm. Demulsification and dehydration continued under this low field strength until oil-water separation was complete. During this process, the pulse electric field frequency was set to 300 Hz during the maximum field strength phase and 200 Hz during the low field strength phase, with a pulse duty cycle of 0.4. Ultimately, testing showed that the water content in the dehydrated oil was reduced to below 0.5%, demonstrating significant demulsification and dehydration effects, and no secondary emulsification was observed throughout the process.

[0024] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dehydration process for an emulsion, characterized in that, Includes the following steps: After mechanical impurities are removed by a filter, the water-in-oil emulsion that needs to be demulsified and dehydrated enters an oil heater and is heated to 20℃~30℃. Then it enters a pulse electric field demulsification and dehydration device, where the pulse electric field is used for demulsification and dehydration. In the pulsed electric field demulsification and dehydration device, the maximum electric field strength of 0.5 kV / cm is used as the initial value. After running for 3 to 5 seconds, the pulse power supply current display is observed. If the current is less than or equal to 0.03 mA, the maximum electric field strength is increased by 0.1 kV / cm to 0.15 kV / cm. The above steps are repeated until the current on the pulse power supply current display is greater than 0.03 mA. The device is then run for another 1 to 3 seconds at the current maximum electric field strength. After that, the electric field strength is reduced by 45% to 55%, and subsequent demulsification and dehydration treatment is carried out until the oil-water separation process is completed.

2. The dehydration process for an emulsion according to claim 1, characterized in that, The pulsed electric field is generated by a pulsed power supply that outputs square wave pulses.

3. The dehydration process for an emulsion according to claim 1, characterized in that, In the pulsed electric field, when the maximum electric field strength is less than or equal to 1.5 kV / cm, the frequency of the pulsed electric field is 50 Hz to 500 Hz.

4. The dehydration process for an emulsion according to claim 1, characterized in that, In the pulsed electric field, when the maximum electric field strength is greater than 1.5 kV / cm, the frequency of the pulsed electric field is 500 Hz to 2500 Hz.

5. The dehydration process for an emulsion according to claim 1, characterized in that, The pulse duty cycle of the pulsed electric field is 0.2 to 0.

5.

6. The dehydration process for an emulsion according to claim 1, characterized in that, The current of the pulse power supply current display is set to I Its unit is mA. If the current is less than or equal to 0.03 mA, the maximum electric field strength will be increased by Δ. E Its unit is kV / cm, the aforementioned I and the mentioned △ E Satisfy the following relationship: △ E =(-5 / 3)× I+ 0.

15.

7. The dehydration process for an emulsion according to claim 1, characterized in that, The operation continues until the current displayed by the pulse power supply current indicator is greater than 0.03mA, at which point the operation continues for the maximum electric field strength. t Its unit is seconds, then it is reduced by a percentage. p After %, subsequent demulsification and dehydration treatments are performed until the oil-water separation process is completed. t and stated p The following relationship must be satisfied: p =45× t 0.1827 .

8. The dehydration process for an emulsion according to claim 1, characterized in that, The pulsed electric field can be a uniform electric field or a non-uniform electric field.

9. The dehydration process for an emulsion according to claim 1, characterized in that, The water-in-oil emulsion that requires demulsification and dehydration treatment has a water content of 5% to 30% (by mass) and a kinematic viscosity of less than 80 mm² / s at 40°C.

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