JPH03296456A - Dehydrating and desalting apparatus - Google Patents

Abstract

PURPOSE:To improve dehydrating and desalting efficiency in low voltage, in arranging opposed electrodes in oil containing waterdrops to flocculate, settle and separate waterdrops under an electric field, by constituting at least one electrodes of flat electrodes having many acute-angle projections. CONSTITUTION:The supply pipe 2 of oil to be treated is opened above the oil-water interface 11 of a treatment-tank 1 and groups of pipe-shaped electrodes 5, 6 horizontally opposed to each other are arranged above the opening of the supply pipe 2 and, further, a flat electrode group 12 containing flat electrodes 13 having many acute-angle projections and flat electrodes 14 vertically opposed thereto is arranged. The recovery pipe 4 of treated oil is opened to the upper part of the treatment tank 1 and the drain pipe 9 of salt-containing water is connected to the bottom part of the treatment tank 1. As a result, dehydrating and desalting efficiency can be improved in low voltage. Further, even oil with low moisture content can be easily dehydrated and desalted and separation efficiency can be also drastically enhanced as compared with a conventional apparatus.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to dehydration of crude oil, heavy oil, fuel oil, petroleum refinery residue oil, and synthetic oils such as coal liquefied oil, oil sand oil, and shale oil. The present invention relates to a device for desalting.

(Prior Art) FIG. 7 is a system diagram of a conventional electrical dehydration and desalination apparatus. A few percent to several tens of percent of fresh water or salt water with a low salinity concentration is injected into the oil 15 to be treated as dilution water 16, and if necessary,
Mixed liquid 1 in which the salts in the oil to be treated are transferred to dilution water by heating them in advance and then injecting them and stirring them with the mixing valve I7.
8 is introduced into the treatment tank 19, a high-voltage electric field is applied to cause the salt-containing water droplets to coagulate, and the enlarged water droplets are separated by sedimentation due to the difference in specific gravity. This is to take out the salt waste water 21.

The apparatus shown in FIG. 8 is a modification of the apparatus shown in FIG. 7, and has two processing tanks. East 2 treatment tank 3 for treated oil 22
The waste water collected from 2 is added as dilution water 24, mixed and stirred in the first mixer 23 to transfer the salt in the oil to be treated to the dilution water, and the first mixed liquid 25 is transferred to the first treatment tank 26. The salt-containing water droplets are coagulated by applying a high-voltage electric field, and the enlarged water droplets are separated by sedimentation due to the difference in specific gravity, and the separated oil 27 is taken out from the top of the treatment tank 26 and the salt-containing wastewater 28 is taken out from the bottom.
Dilution water 29 is added to the separated oil 27 from outside the system, mixed and stirred in a second mixer 30, and the second mixed liquid 31 is mixed in a second mixer 30.
The salt-containing water droplets are introduced into the treatment tank 32, and a high-voltage electric field is applied again to cause the salt-containing water droplets to coagulate, and the enlarged water droplets are separated by sedimentation due to the difference in specific gravity. 24 is taken out, and the dilution water 24 is returned to the first mixer 23 by a pump 33.

5 and 6 are conceptual diagrams showing the structure of a treatment tank of a conventional electric dehydration and desalination apparatus, with FIG. 5 being a front sectional view and FIG. 6 being viewed from the I-1 arrow in FIG. FIG. In order to introduce the oil to be treated into the treatment tank 1, a distribution pipe 3 connected to the supply pipe 2 is opened above the oil-water interface 11, and above it, vibrator-shaped counter electrodes 5 and 6 with closed ends are placed horizontally. Place and power supply 7
The treatment tank 1 is connected to the above electrode via an insulator 8, an oil recovery pipe 4 is connected to the top of the treatment tank 1, a drain pipe 9 is connected to the bottom, and an interface meter 10 is arranged to detect the oil-water interface.

In this treatment tank, a high voltage is applied between the pipe-shaped opposing electrodes 5 and 6 to charge the salt-containing water particles between the electrodes, and the particles are coagulated by applying an attractive force to each other using electrostatic force. It promotes The suction force at that time can be expressed by the following formula.

F = kE 'a'/d'
(1) F: Attraction force E between salt water particles, potential gradient a: Radius of salt water particles d: Distance between salt water particles: Constant Acts between particles in the oil to be treated as shown by this formula The suction force is proportional to the sixth power of the particle size and inversely proportional to the fourth power of the distance between particles. For this reason, conventionally, by injecting dilution water and mixing and stirring, the number of salt-containing water particles in the oil to be treated was increased, the distance between the particles was reduced, and aggregation and coalescence was promoted.

(Problem to be solved by the invention) However, in the above device, the coagulation and sedimentation of water droplets progresses from the large-sized ones, so as time passes, small-sized water droplets remain and the distance between the water droplets increases. Therefore, the attraction force decreases rapidly as shown in equation (1) above, and a coagulation effect cannot be expected. Excessive voltage rise causes problems such as the occurrence of short circuits and increased equipment costs for introducing high voltage equipment, and the practical electric field strength is set at an upper limit of 5 KV/cm. As shown in Figure 8, dilution water in the latter stage is mixed into the treatment tank in the former stage to reduce the salt concentration in the oil to be treated, and also to increase the particle size and number of water droplets. Although attempts have been made to improve the dehydration and desalination efficiency, the scale of the equipment increases, which increases costs, including the need to secure dilution water.

Therefore, the present invention aims to solve the above-mentioned problems and provide a device with low voltage and high dehydration and desalination efficiency.

(Means for Solving the Problems) The present invention provides a dehydrating and desalting apparatus in which a counter electrode is disposed in oil containing water droplets and the water droplets are coagulated and sedimented under an electric field. This is a dehydration/desalination device characterized by a flat plate electrode having protrusions (hereinafter referred to as a flat plate electrode with spikes).

In addition, when using a conventional counter electrode group in combination with an electrode group including flat plate electrodes with barbs, both can be incorporated into one processing tank main body, or they can be integrated into separate processing tanks. is also possible.

When incorporating into another treatment tank, the water droplets in the oil to be treated are coagulated and coalesced in the first processing tank, and then further coagulated and coalesced in the electrode group including the barbed flat plate electrode in the second treatment tank. This method also performs sedimentation separation.

(Function) FIGS. 1 to 4 are conceptual diagrams of a processing tank of a dehydration and desalination apparatus that is a specific example of the present invention, and FIG. 1 is a front sectional view, and FIG.
The figure is a sectional view taken along the line II in FIG. 1, and FIGS. 3 and 4 are enlarged views of the barbed flat plate electrode group. This processing tank has a group of flat plate electrodes with barbs arranged above the pipe-shaped horizontally opposed electrodes of the conventional apparatus shown in FIGS. 5 and 6 above. Therefore,
The explanation will focus on vertically opposed electrodes including flat plate electrodes with spikes.

The barbed flat plate electrode group 12 shown in FIGS. 3 and 4 has a barbed flat plate electrode 13 and a flat plate electrode 14 facing each other, but both employ barbed flat plate electrodes and arrange the two to face each other. It's okay. Further, the vertically opposed electrode group including the barbed flat plate electrode group may be arranged in a separate processing tank.

By the way, the oil to be treated is sent to an electric field formed between pipe-shaped horizontally opposing electrodes, and the water droplets in the oil are charged and coagulate due to electrostatic attraction, but the water droplets do not cohere. As sedimentation progresses from large-sized particles, small-sized water droplets remain as time passes, and the distance between the water droplets increases, causing the suction force to decrease and coagulation to virtually stop, causing the water droplets to It behaves as a single particle and no longer migrates to the counter electrode.

However, minute water droplets are easily attracted to the positive electrode, and furthermore, when a flat plate electrode with spikes is used, an unequal electric field is formed centered at the tip of the flat plate electrode. The water droplets are attracted to the tip of the attached flat plate electrode and agglomerate, easily promoting enlargement of the water droplets. On the other hand, since the electric field is uniform between the pipe-shaped electrodes, the force of attracting water droplets to the electrodes is relatively weak, and the attracted water droplets are not concentrated at one point on the electrodes.
The rate at which the water droplets coagulate and enlarge is also not large. Furthermore, in a field where an unequal electric field is formed, an electrohydrodynamic phenomenon (Electric Hydrodynamic
cFlow) causes stirring convection, which increases the frequency with which water droplets approach the electrode and promotes aggregation at the electrode. Note that the current flowing through the barbed flat plate electrode may be alternating current or direct current. However, when flowing direct current, it is preferable to connect the barbed flat plate electrode to the positive terminal. This is because water droplets are attracted by the positive electrode.

In the treatment tank 1 mentioned above, the oil to be treated with a high water content is supplied from the distribution pipe 3, and first, the pipe-shaped counter electrodes 5, 6
The water droplets are agglomerated and coalesced, and the enlarged water droplets are allowed to settle, while the oil to be treated with a reduced water content is raised and sent to the barbed flat electrode group 12, which connects the barbed flat plate electrode I3 and the flat plate electrode assembly. Microscopic water droplets are coagulated by the unequal electric field between 4 and the enlarged water droplets are discharged from the drain pipe 9 at the bottom of the treatment tank 1, and the dehydrated and desalted oil is drained from the collection pipe at the top of the treatment tank 1. 4 Remove the strands from the outside. In addition, barbed flat plate electrode group 1
2 is placed in another processing tank, the water droplets are coagulated and coalesced in the processing tank body having a pipe-shaped counter electrode, enlarged to some extent, sedimented and separated, and then sent to the barbed flat plate electrode group 12, and further, Coagulation and sedimentation are performed to perform dehydration and desalination treatment.

(Example) Using the treatment tank shown in FIG. 9, a dehydration experiment was conducted by supplying light oil containing 0.5 wt% water at a rate of 81/hr.

Note that the average particle size of water droplets in the light oil was about 13 μm.

The flat electrode facing the barbed flat electrode has an area of 120c.
m', 52m of stainless steel thin plate with a thickness of 0.5+nm
vertically arranged at intervals of m, with a distance of 25 mm between the thin plate electrodes.
A flat plate electrode with spikes was provided vertically so as to be parallel to the position. The barbed flat plate electrode is made by folding a flat plate having a thickness of 0.5 mm alternately in a V-shape on both sides at intervals of 10 mm vertically and horizontally so that the height of the spines is 5 mm+.

Then, for the flat plate electrode and the flat plate electrode with spikes,
When alternating current was passed for 1 hour at 0 V (electric field strength IKV/cm), 8 g of light oil with a water content of ff1O, 06 wt% could be obtained.

(Comparative Example) For comparison, a treatment tank having a flat counter electrode as shown in FIG. 10 was used to treat light oil containing 0.5vt% water at
hr, and a dehydration experiment was conducted. Note that the average particle size of water droplets in the light oil was about 13 μl. The planar counter electrode was made of thin stainless steel plates with an area of 120 cm and a thickness of 0.51 cm, which were vertically arranged at intervals of 25 cm, and when alternating current was applied at 2500 V (electric field strength IKV/cm) for 1 hour, the moisture content was measured. 0.21) yt% of light oil was obtained.

(Effects of the Invention) By adopting the above configuration, the present invention can easily dehydrate and desalinate even oil with a low water content, and the separation efficiency is dramatically improved compared to conventional equipment. I was able to do that.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view of a processing tank of a dehydration and desalination apparatus which is a specific example of the present invention, FIG.
4 and 4 are enlarged views of the barbed flat electrode group used in FIG. 1, FIG. 5 is a front cross-sectional view of a conventional processing tank, and FIG. 6 is a cross-sectional view taken along arrow I-1 in FIG. Figures 7 and 8 are system diagrams of conventional electrical dehydration and desalination equipment, Figure 9 is a sectional view of the dehydration and desalination equipment used in the examples, and Figure 10 is the diagram of the dehydration and desalination equipment used in comparative examples. FIG. 5゛Nishiki 3 Lightning Figure 7 Figure 8 ¥9 Figure Ryo Figure 10

Claims (3)

[Claims] (1) In a dehydration/desalination device in which a counter electrode is placed in oil containing water droplets and the water droplets are coagulated and separated under an electric field, a flat electrode having a large number of acute-angled protrusions is used as at least one electrode. A dehydration desalination device characterized by: (2) A supply pipe for the oil to be treated is opened above the oil-water interface of the processing tank, a group of horizontally opposing electrodes is arranged above the opening, and a flat plate having a large number of acute-angled protrusions is placed above it. The method is characterized in that an electrode group including a shaped electrode and an electrode perpendicularly opposed thereto is arranged, a recovery pipe for treated oil is opened at the top of the treatment tank, and a drainage pipe for saline water is connected to the bottom of the treatment tank. The dehydration desalination apparatus according to claim (1). (3) A group of counter electrodes is arranged in a first treatment tank into which oil containing water droplets is introduced, and a second treatment tank connected to the tank via a conduit is provided with the oil to be treated above the oil-water interface of the tank. A supply pipe is opened, and an electrode group including a flat electrode having a large number of acute-angled protrusions and an electrode facing perpendicularly thereto is arranged above the opening;
2. The dehydration and desalination apparatus according to claim 1, further comprising a recovery pipe for treated oil opened above the treatment tank, and a drain pipe for saline water connected to the bottom of the treatment tank.