Method of oil/water separation and device for purification of oil

This invention provides a new low vacuum oil/water mixture liquid separation method and an improved oil purification device for oil/water separation. Fully diffused purified gas is introduced into an oil/water mixture liquid in a low vacuum container, enabling the liquid to produce concentrated micro fine gas bubbles, enabling in the liquid to be in a state of gas/liquid two-phase mixture. This greatly increases the surface area of the oil/water mixture liquid, speeding up the oil/water separation. This invention provides an oil/water separation rate ten times higher than that of the conventional method. This invention is not only suitable for the purification of new oil, but is adequate in the recovery, regeneration and purification of various waste lubrication oils, hydraulic oils, and transformer oils.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention involves a low vacuum high-speed method for oil/water 
separation for mixture liquids or emulsions liquids of oil and water, as 
well as a device for purification of oil for low vacuum separation of 
oil/water and oil/gas, mainly used in industrial oils: the refinement of 
fresh oils as well as the recovery, regeneration and refinement of 
industrial waste oils. 
2. Description of Related Art 
With the speedy development of science, technology and industries, the 
demands of the degree of purification and refinement for industrial oils, 
such as lubrication oils, hydraulic pressure oils, and transformer oil, 
are becoming increasingly strict and the amount of oils consumed also 
grows daily. Subsequently, in industries, the refinement of fresh oils not 
only has to be up to the stipulated standards, but the discarding of waste 
oils is not permissible by environmental laws and the law on the 
utilization of resources as well. Furthermore, this is also impractical in 
consideration of production cost. Thus, the recovery, refinement and 
regeneration of huge amounts of waste oils are involved; the waste oils 
are made to reach the stipulated standards for use. In addition, when 
being used, the oils are also being contaminated at a high speed. 
Therefore, for oils in the process of being used, continuous purification 
is also needed to ensure normal operation of the equipment. 
In the process of being used, contamination of the oils can produce great 
damage. For example, in hydraulic pressure systems, the rate of accidents 
caused by the contamination of oils can reach as high as 82%, while for 
electric and mechanical systems, only 18%. When transformer oils become 
off standard, the transformer will be in danger of being punctured. 
The most harmful contaminants in oils are: water, gases, solid particles, 
and the like among which water can reduce the viscosity of the oils, thus 
making the oils out of conformity with the usage demand, water can also 
lower the membrane strength of the oils or break the oil membrane, 
resulting in accelerated wear and tear of the equipment; water and air can 
make the requisite chemical additives in oils become ineffective, 
producing acidic substances and speeding up the aging of the oils. While 
in operation, the life span of waterless transformer oil is 5.6 times 
that of water-containing transformer oil. As for hydraulic pressure 
systems, water and air enhance the gas hole phenomenon, thus affecting the 
stability, increasing the vibration and noises of the system, shortenting 
the life span of the equipment, and even creating accidents. 
The water in oils is not only very harmful, but to separate it from the 
oils is also rather difficult. For oils with higher viscosity, when oil 
and water mixes, and when the mixture undergoes agitation during the 
equipment's operation, the mixture rapidly emulsifies; separation of the 
water from the oils at this state is even more difficult, especially the 
oils containing various chemical additives. The additives strengthen the 
oil/water emulsification, and this enhances the difficulties of 
separation. For example, there has not been a good device up to the 
present that can quickly separate the water from the hydraulic pressure 
oil. Besides, in the field of the purification of oils, the purification 
is usually being conducted by adopting chalk, silica gel, or activated 
carbon. However, when the water content is high, water can quickly render 
these absorbents ineffective. Therefore, it is necessary to first 
eliminate the greater part of the water. 
Thus, the separation of oil/water is both very important and very 
difficult. The technology of low vacuum separation of oil/water and 
oil/gas as well as well as of the purification of oil has long been 
emphasized by people in the field of industry. There are many conventional 
devices in this respect, most adopting methods like these: pass the 
oil/water mixture (including emulsion) liquid through the spray element 
which is deposited at the top of the vacuum container or column, spray it 
into fine drops, then fall onto the filler or grid at the lower part, thus 
increasing the areas of interface of the two gas/liquid phases of the 
liquid, at the same time the resulting droplets are obstructed by the 
filler, thus prolonging the retaining periods of the liquid droplets or 
the thin liquid layers in space. The chances for the evaporation of the 
water in the oil are thus increased. Because the saturated steam pressure 
of the oil is very low, under this state, the oil evaporates very little, 
resulting in the gas and part of the water being separated under a low 
pressure, thus achieving the goal of oil/water separation and oil/gas 
separation. Finally, the oil or oil/water liquid falls to the lower part 
of the container, which is pumped or extracted to enter into the spray 
element again for recycle dewatering. 
From the theory of mass transfer, it is known that the separation of 
oil/water is actually the evaporation of one component that is easier to 
evaporate in a two component mixture liquid. Under definite temperature or 
pressure (or in vacuum), it is required that the liquid possess the 
biggest possible interface areas of the two gas/liquid phases, therefore, 
the longer the liquid droplets or the liquid thin layers remain in the 
gaseous phase the better, the two gas/liquid phase interfaces should 
speedily renew. Only thus can the water in the oil/water mixture liquid be 
quickly separated out of the mixture. However, in the above conventional 
method using spray and filler there exist the following deficiencies: 
First, the capability of the spray plus filler to increase the interfaces 
of the two phases of liquid/gas is limited; second, the capability of the 
filler in obstructing, thus delaying the liquid from falling is even more 
limited; third, as the viscosity of oil increases, the surface of the oil 
is difficult to be renewed. These three factors limit the oil/water 
separation speed of the above conventional method. 
The object of this invention is to provide a new method for the separation 
of oil and water, which differs from the conventional method in that oil 
and water can be rapidly separated under the same temperature and absolute 
pressure (vacuum); it also provides low vacuum oil/water separation, 
oil/gas separation using said method, as well as a device for the 
purification of oil. 
SUMMARY OF THE INVENTION 
The object of this invention is realized through the following technical 
process: 
Introduce into the oil/water mixture or emulsion liquid a gas that has been 
purified; make the gas fully diffused in the liquid, forming a large 
amount of concentrated and very fine gas bubbles, thus making the liquid 
be in a 2-phase mixed state. The method of diffusing the gas is to pass 
the gas through a bubble generator made of microporous materials. The 
materials that manufacture the bubble generator are powdered sintered 
metal, powdered sintered ceramics, press-shaped powdered plastics, 
press-shaped powdered resin, multilayer net cloth or other micro porous 
materials. The structures of the bubble generator are vacant sphere, 
vacant bar, vacant ring, and vacant plate, shaped. The direction of 
movement of the gas is: After the gas is introduced into the chamber of 
the bubble generator, pass through the inner surface of the micro porous 
wall to the outer surface, subsequent to which it enters the liquid 
proper, forming concentrated fine bubbles. As the liquid is in a low 
vacuum container, the absolute pressure of the liquid is very low, 
resulting in bubble expansion immediately upon their arrival in the liquid 
and further expansion in the process of floating upward. The absolute 
pressure within the gas bubbles being much lower than the saturated steam 
pressure of water as well as the separation pressure of the gas in the 
oil, the water content in the oil unceasingly evaporates into the gas 
bubbles. Gas is also separated into the gas bubbles finally, when the gas 
bubbles reach the top part of the liquid, they break; finally, the steam 
and gas are discharged from the vacuum outlet of the container. At this 
state, as the saturated steam pressure of the oil is very low, the oil 
evaporates but little, thus achieving the aim of the separation of the 
oil/water and the separation of oil/gas. 
The two-phase mix state of the gas and liquid in the oil/water mixture 
liquid makes water evaporate rapidly under low vacuum conditions, the 
mechanism of which lies in: 
1. Huge amounts of gas bubbles are dispersed in the liquid, resulting in 
the great increase of the two-phase interfaces of the gas and liquid. This 
is incomparable by the method which employs fillers to increase the 
surface area of the liquid. 
2. The movements of matter are all relative. If one point on a certain 
floating-upward bubble is taken as a reference coordinate initial point, 
then, in this coordinate system, the floating-up bubble may seem to be not 
moving but the liquid surrounding the bubble seems to be dropping down 
continuously. This is to say, though the height of the container or column 
is very limited and unchanged, the relative movements between the gas 
bubbles and liquid will proceed continuously provided that the gas bubbles 
are continuously produced and floating-up. Therefore, if only the period 
for the production of gas bubbles is made to be sufficiently long, then 
the period of the liquid's remaining in space is equivalent to being 
sufficiently long, and the water in the oil will continuously evaporate 
into the bubbles. Any conventional methods employing fillers to obstruct 
the falling of the liquid to prolong the remaining period of the liquid in 
space can not be compared with this one. 
3. As the gas bubbles remain in the stage of continuously expanding and 
floating upward, the liquid surrounding the gas bubbles at any instant is 
different. That is, the two gas/liquid phase interfaces are being rapidly 
renewed continuously. The difficulties of the large viscosity of the 
liquid as well as of the surfaces being hard to renew are overcome. The 
renewal of the liquid surface enables the exposure of the water molecules 
on to the surface, thus speeding up evaporation. The conventional methods 
can not be compared with this. 
From the above analysis of the mechanism, the differences and superiority 
are obvious when adopting the gas/liquid mixed two-phase method as 
compared with the conventional spray plus filler method. 
It can easily be seen that the gas/liquid mixed two-phase method for the 
separation of oil/water mixture liquid as provided by this invention can 
also be used in: rapid evaporation and separation of the component(s) 
easier to be evaporated in two-component or multi-component mixtures, and 
such industrial areas as the evaporation of liquids, as the concentration 
of salt solutions, etc. 
This invention also provides improvements for separation and purification 
devices of low vacuum oil/water separation and oil/gas separation 
featuring the above mentioned gas/liquid mixed two-phase method. The 
following are elucidation for the respective procedure together with its 
device: 
The system of the method of this invention comprises five parts: (1) the 
low vacuum container, (2) the gas bubble producing system procedure, (3) 
the input procedure of oil/water mixture liquid, (4) the vacuum exhaust 
procedure, (5) the output procedure of purified oil. The five parts are 
respectively described as follows: 
(1) The low vacuum container or column 
The low vacuum container or column can be divided into two kinds: 
single-chamber type or multi-chamber type. The single-chamber is one 
container or column which has only one chamber. The multi-chamber type 
means: first, several single chamber containers or columns are serially 
connected together, that is, the oil/water mixed liquid continuously flows 
starting from the entrance of the first container or column and reaching 
its exit, and this exit is the entrance of the second container or column, 
and so on and so forth, until the liquid reaches the exit of the last 
container or column. Several single containers or columns in series form a 
combined unit. Secondly, there are several partitions in a big container 
or column, these partitions not only divide the big chamber of the 
container or column into several small chambers, but the liquid also 
continuously flows starting from the entrance of the first small chamber 
and reaching its exit, and this exit is the entrance of the second small 
chamber where the liquid enters, and so on and so forth, until the liquid 
reaches the exit of the last small chamber. The big container or column is 
the collective body of several serially connected small chambers. Thirdly, 
several containers or columns are parallel-connected, which means there is 
a general liquid entrance pipe-line connecting with several parallel 
sub-pipe lines which are linked with the liquid entrance of the respective 
container or column. There is also a general exit pipe-line for the 
purified oil which gas several sub-pipe lines parallel-connected with it 
and which is linked with the purified oil exit of the respective container 
or column. Several containers form a container combination connected in 
parallel. In performance, while the oil/water mixture liquid enter one or 
one part of the containers or columns, oil/water separation is being 
carried on simultaneously in the second or second part of the containers 
or columns, and the third or third part of the containers or columns is 
discharging purified oil at the same time. After the third or the third 
part of containers or columns has finished the discharging of the 
purification of the oil, the process is changed into the procedure of 
inputting the oil/water mixture liquid. Simultaneously the first or the 
first part of the containers or columns change into the oil/water 
separation procedure and the second or second part of containers or 
columns changes into the discharging of purified oil. Changes like this 
are being proceeded in turn; the oil/water mixture liquid may also be 
introduced continuously into the combination body of the containers 
connected in parallel or columns and the body continuously discharges the 
purified oil. There is an appropriate amount of space at the top part of 
each of the container or column and its chamber which is connected with 
the vacuum port to discharge steam and gas. Except for the discharge port, 
there are several gas bubble generators in the container or column and its 
chamber, thus making the liquid change into the state where the two phases 
of gas and liquid mix together. The work vacuum of the container or column 
and its chamber is between 700 mmHg and 1.times.10.sup.-3 mmHg. The 
function of the vacuum container or column and its chamber is such that 
water and gas are separated and discharged under the two-phase state of 
gas and liquid being mixed together. 
(2) The procedure of gas bubble generating system 
This system includes two parts. The first is the gas treating and supplying 
part, providing gas that conforms with the requirements, including gas 
source, gas intercept valve, gas filter, gas dryer, gas heater, gas 
current regulating valve, gas intercept valve and the corresponding pipes 
that connect them. The second is several bubble generators and the pipes 
that connect with the gas supplying part. Among them, the gas treating and 
supplying part is on the outside of the container or column and its 
chamber, while the gas generators and their gas pipes are in the inside of 
the container or column and its chamber, and its connecting pipes pass 
through the wall of the container or column and connects with the 
supplying part. The bubble generators shall be guaranteed to be immersed 
in the liquid. The function of this procedure is to make the liquid in the 
container or column and its chamber reach a state of gas/liquid two-phase 
mixture. 
(3) The procedure of the input of the oil/water mixture liquid 
This procedure is similar to the conventional low vacuum oil purification 
device, comprising of the following parts: inlet valve, coarse oil-filter, 
input pump, pump safety valve, oil heater, oil temperature controller, 
fine oil-filter, precision switch of the pressure difference of the fine 
oil-filter, flow regulation valve, intercept valve and the corresponding 
pipes that connect them. It communicates with the inlet of the input 
chamber of the vacuum container or column. The function of this procedure 
is to provide the container or column and its chamber with a definite 
amount of oil/water mixture liquid with adequate temperature and at the 
same time filter away a greater part of the solid particles. 
(4) The procedure of vacuum exhaust 
The procedure is similar to the low vacuum exhaust procedure of the 
conventional low vacuum oil purification device, comprising the following 
parts: vacuum meter, vacuum exhaust valve, condenser, water storage tank, 
vacuum pump and the corresponding pipes that connect them. It connects 
with the vacuum port of the container or column and its chamber. The 
function of the condenser is to condense the steam into water, after which 
water enters the water storage tank, thus preventing the steam from 
entering the vacuum pump and influencing normal operations, while the gas 
is removed by the vacuum pump. The function of this procedure is: on the 
one hand, a definite vacuum is maintained in the vacuum container or 
column and its chamber, and, on the other hand, steam and gas are 
exhausted. 
(5) The procedure of output of purified oil 
This procedure is also similar to the output procedure of the conventional 
low-vacuum oil purification device. The procedure is connected by passing 
the output port of the vacuum container or column and its chamber, through 
the intercept valve, output pump, safety valve of the pump, reverse 
direction valve, fine oil-filter, flow regulating valve, flow meter, 
intercept valve and the corresponding connection pipes. The function of 
this procedure is: further filter away the solid particles in the oil; 
discharge purified oil which conforms with the standards in water and in 
gas content and in solid particle contamination.

The following are further detailed illustration of this invention referring 
to the attached drawings and examples: 
DESCRIPTION OF PREFERRED EMBODIMENTS 
1. Low vacuum oil purification device of single-chamber type with 
intermittent treatment 
FIG. 1 is a schematic view of the procedures of a low vacuum oil 
purification device of a single chamber type with intermittent treatment, 
comprising: a single-chamber type low vacuum container, a procedure of gas 
bubble generating system, a procedure of input of oil/water mixture 
liquid, a procedure of vacuum exhaust, and a procedure of purified oil 
output. The respective parts and performance procedures are introduced as 
follows: 
(1) Single-chamber type low vacuum container or column 
In FIG. 1, element 16 is a cylindrical upright sealed container; the bottom 
is the discharge port of purified oil; located at the bottom is the oil 
heater 18 and the corresponding oil temperature controller; a little above 
18 are several (only five are shown in the figure) hollow sphere-shaped 
bubble generators G which are circularly arranged. A little above G is a 
controller 17 for the lower liquid surface; a controller 17 is to the 
upper liquid surface, the function of which is to prevent the liquid from 
being added to the top part of container 16, thus maintaining a suitable 
space at the top part of the container and to prevent the liquid from 
discharging from the vacuum port while letting the steam and gas to 
discharge from the vacuum port. The vacuum port is located at the highest 
part of container 16. The working vacuum of the container is between 110 
mmHg and 260 mmHg. 
(2) The procedure of the gas bubble generating system 
The gas bubble generators are the key part of this invention and more 
detailed description is necessary. FIG. 2 is the front schematic view of 
the rectangular arrangement of the hollow sphere-shaped gas bubble 
generators. In the figure, G.sub.11, G.sub.21 . . . G.sub.n1 are 
sphere-shaped bubble generators, L is the general gas-communicating pipe, 
l.sub.11, l.sub.21 . . . l.sub.n1 are parallel sub-pipes connecting the 
gas bubble generators with the general pipe. FIG. 3 is a top schematic 
view of the rectangular arrangement of the sphere-shaped gas bubble 
generators. In the figure, G.sub.11 G.sub.12 . . . G.sub.1n, up to 
G.sub.n1 G.sub.n2 . . . G.sub.nn, are the respective gas bubble 
generators. FIG. 4 is a sectional schematic view of the center of the 
sphere-shaped gas bubble generator, in which Sr is the inner diameter of 
the hollow sphere, while SR is the outer diameter of the sphere. A 
rectaugular arrangement only is shown here, which is more suitable to be 
arranged in horizontally positioned cylindrical containers. For the 
above-mentioned upright cylindrical containers, a circular-shaped 
arrangement is more suitable. 
In FIG. 1, the general gas-communicating pipe penetrates the container wall 
and connects with the intercept valve of the gas treatment and supply 
part. The gas treatment and supply part comprises: a gas source 1, an 
intercept valve 2, a gas filter 3, a gas dryer 4, a gas heater and its 
temperature controller 5, a gas regulating valve 6, a gas intercept valve 
7 and their corresponding connecting pipes. The gas starts from gas source 
1, respectively passes through 2, 3, 4, 5, 6 and 7 and enters into the 
hollow chamber of the respective gas bubble generators G. The temperature 
of the gas is the same as that of the oil. 
(3) The input procedure of the oil/water mixture liquid 
In FIG. 1, the contaminated oil containing solid particles and water 
successively enters from intercept 8 into the procedure, flowing through 
coarse oil filter 9, input pump 10, heater and its temperature controller 
12, fine oil filter 13 and intercept valve 15, then entering container 16. 
The function of the coarse filter 9 is to protect pump 10, and to share 
the amount of the contaminants to be filtered with fine filter 13. A 
safety valve 11 is provided for pump 10. Heater 12 raises the temperature 
of the liquid and controls the temperature within an allowable range. Fine 
filter 13 filters the greater part of the solid particle from the liquid. 
Coarse filter 9 and fine filter 13 realizes the first step of 
purification--the elimination of solid particles. Element 14 is pressure 
difference switch; when the contamination amount is too big for fine 
filter 13, the pressure differences increase, thus triggering pressure 
difference switch 14; this makes the whole device stop its operation until 
the filter core is changed or cleaned, and then the device is started 
again. The intercept valve 15 closes when the charging of oil is stopped 
to protect the vacuum of container 16. 
(4) The procedure of vacuum exhaust 
The gas penetrates through the micro pores in the wall of gas bubble 
generator G and enters into the liquid. As the liquid is in the vacuum 
container, therefore it is in a state of low pressure. The fine gas 
bubbles in the liquid expand, and float up during this process. As the 
absolute pressure within the gas bubbles (actually the gases in bubbles 
are also in a state of vacuum) is far lower than the saturated steam 
pressure and the separation pressure of the gas in the oil, the water 
content in the oil continuously evaporates into the gas bubbles, and the 
gas also enters into the gas bubbles. When the gas bubbles float up to the 
place 17' having the liquid pressure, the gas bubbles will break, and the 
steam and gas will exhaust from the vacuum port of container 16. 
In FIG. 1, element 19 is a vacuum pressure meter. The gas and steam 
discharged from the vacuum port at the top of container 16 arrive in 
condenser 20. The greater part of steam is condensed into water, flowing 
downward into water storage tank 22 while the gas is exhausted by vacuum 
pump 21. Element 22 is the liquid surface controller for water storage 
tank 22. When the water level reaches the controller 22, controller 22' 
and is triggered. Vacuum pump 21 stops operating, valve 23 opens to 
discharge water. 
(5) The procedure of the output of purified oil 
In FIG. 1, the longer the period for the vacuum separation procedure for 
gas/liquid two-phase mixture, the lower the water content in the oil. If 
the gas treatment and supply part can provide enough dry gas, then the 
water content in the oil can be lowered at will with the prolongation of 
the treatment period, and can be as low as below 1 ppm. When the water 
content in the oil reaches the stipulated standard, valve 7 closes. From 1 
to 2 minutes afterwards, after the remainder gas is exhausted, vacuum pump 
21 closes, opening the vacuum gas filling valve 24 that connects with gas 
dryer 4 makes container 16 recover pressure. When intercept valve 25 that 
protects the vacuum extent in container 16 is open purified oil is 
discharged through oil output pump 26, reverse-checking valve 28 and again 
through fine oil filter 29 for further filtering, and purified oil is 
discharged from output intercept valve 30. The purified degree of the 
solid particle of the oil depends upon the precision grade of the fine oil 
filters 13 and 29. 
(6) The work procedure of the device 
The work begins when the oil/water mixture liquid enters the procedure, the 
lower surface controller 17 is triggered, at this time the procedures of 
gas bubble generating system and vacuum exhaust simultaneously start 
working. When the liquid arrives at 17' the upper surface controller 17' 
is triggered, the oil input procedure stops working, and the intercept 
valve 15 closes. When the water content of the oil reaches the designated 
water content level, the gas generating system stops working, and valve 7 
closes. One and two minutes later, the vacuum exhaust procedure stops 
working at the same time gas-filling valve 24 opens and container 16 is 
filled with gas and recovers pressure. At this time, the purified oil 
output procedure starts working, discharging purified oil until container 
16 is exhausted. 
2. Multi-chamber type low vacuum oil purification device with continuous 
treatment 
FIG. 5 is a schematic view of the procedure of this device; different parts 
and the work procedure are illustrated as the following: 
(1) Multi-chamber type low vacuum container 
FIG. 6 is a front schematic view of a multi-chamber type container. In the 
FIG. 31 is the wall of the horizontal cylindrical container. Element 32 is 
the input port of the oil/water mixture liquid. Element 33 is the output 
port of the purified oil. Member 34 is the lower partition board, 35 is 
the upper partition board, and 36 is the vacuum port. At the lowest part 
of the container there are four valves used for exhaust during change of 
oil or cleaning, and they all communicate with output port 33. FIG. 7 is a 
side view of the lower partition board. In the FIG, 31 is the container 
wall, and 34 is the lower partition board. The top empty part of board 34 
is the discharge route for the steam and gas. The left side of the 
partition is a little higher than the right, thus preventing the oil/water 
mixture liquid from reversely flowing back to the left again after 
overflowing to the right. FIG. 8 is a side schematic view of the upper 
partition board. In the FIG, 31 is the container wall, and 35 is the upper 
partition board. The top empty part is the discharge route of the steam 
and gas, while the lower empty part is the route for oil/water mixture 
liquid. The upper partition board is higher than any of the lower 
partition boards. There are altogether four lower partitions and three 
upper partitions. The big container 31 is partitioned into eight small 
chambers, forming a multi-chamber type container. The oil/water mixture 
liquid enters from inlet 32, then advances forward along the arrow of the 
dotted line (as illustrated in FIG. 6), flowing through the first small 
chamber on the left, overflowing the top of the first lower partition 
board into the second small chamber, i.e. the outlet of the first small 
chamber on the left is the inlet of the second small chamber, and so forth 
and so on, until the outlet 33. Obviously, the respective small chamber is 
serially connected. 
The above description of FIGS. 6,7 and 8, the structure of the 
multi-chamber container 31 in FIG. 5 is easy to understand. In order to 
simplify FIG. 5, the exhaust valves at the lower part of container 31 are 
not marked in the figure. In FIG. 5, the gas bubble generators G are 
arranged at the lower part of all seven small chambers on the left. 
Referring to container 31 as a whole, they are arranged in a rectangle 
(refer to FIGS. 2 and 3). The general gas-communication pipe penetrates 
through the container wall and connects with valve 6' at outside of the 
gas treatment and supply part. In FIG. 5 element 55 is the controller of 
the upper liquid surface and, 56 is the controller of the lower liquid 
surface. The working vacuum of the container is between 260 mmHg and 
1.times.10.sup.- mmHg. 
Acted on by the large amount of gas bubbles, part of the water in the 
oil/water mixture liquid is evaporated as it passes through each of the 
small chambers and is exhausted from vacuum port 36. The nearer the small 
chamber to the output port the lower the water content of oil is. 
Therefore, the greater the number of chambers, the higher the precision of 
the oil/water separation is. In addition, the lower the flow rate or the 
smaller the flow speed through the small chamber, the higher the precision 
of the separation is. In this way, even if the water-content of the 
oil/water mixture liquid is very high, if the liquid is consecutively 
passing through the multi-chamber type container, the water-content in the 
oil can still reach the stipulated standard when it reaches the outlet. 
(2) The procedure of the gas bubble generating system 
In FIG. 5, the gas treatment and supply part includes: gas source 1', 
intercept valve 2', gas filter 3', gas dryer 4', gas heater and its 
temperature controller 5', gas regulating valve 6' and their corresponding 
pipes that connect them. Valve 6' connects with the general gas pipe, that 
comes out from container 31. The temperature of the input gas is the same 
as that of the input oil in container 31. 
(3) The procedure of the input of oil/water mixture liquid 
In FIG. 5, the procedure of the continuous input includes: intercept valve 
37, coarse oil filter 38, oil pump 39, safety valve 40, oil heater 41, oil 
temperature controller 42, fine oil filter 43, pressure difference switch 
44, flow regulating valve 45 and the corresponding pipes that connect 
them. Regulating valve 45 connects with inlet 32. Aside from flow 
regulating valve 45, the function of respective parts is similar to the 
input part of single-chamber type container. Through the flow regulating 
of valve 45, the separation precision of oil/water separation of container 
31 is chosen. 
(4) The procedure of the continuous output of purified oil 
In FIG. 5, the procedure of the continuous output of purified oil includes: 
output pump 57, safety valve 58, checking reverse valve 59, fine filter 
60, flow regulating valve 61, flow meter 62, discharge valve 63 and the 
corresponding pipes that connect them. The entrance of output pump 57 
connects with the exit 33 of container 31. The function of flow meter 62 
is to measure the treated amount. The function of flow regulating valve 61 
is: when controller 55 of the upper surface of the liquid is triggered, 
the flow rate of valve 61 can be regulated to a larger amount, thus 
avoiding the liquid being much higher than the top end of the respective 
lower partition board. When the controller 56 of the lower surface of the 
liquid is triggered, the flow rate of valve 61 can be regulated to a 
smaller amount, thus avoiding pump 57 from pumping nothing and affecting 
its life-span and assuring the continuous discharge. That is to say, pump 
61 is to make the flow input of the device match the flow output, 
ascertaining that the device operates continuously and normally. The 
function of the other parts are similar to those of the single-chamber 
type container. 
(5) The procedure of the vaccum continuous exhaust 
In FIG. 5, 46 is the vacuum meter. After the steam and in the respective 
chamber have reached the upper space of container 31, they pass into 
vacuum port 36, then to condenser 47. The steam is exhausted from vacuum 
pump 48, the water in the condenser flows downward to the sub-water 
storage tank 49, then further lower down past the two-site two-pass valve 
50 into the main water storage tank 51. When the water level of the main 
water storage tank 51 reaches the upper liquid level controller 52, 
controller 52 is triggered, causing valve 50 to close and the two-site 
two-pass valve 54 to open, so that water flows out through valve 54. As 
valve 50 is closed at this time, therefore the discharge of water does not 
affect the working vacuum of container 31. When the water level is lowered 
to the lower liquid level controller 53, controller 53 makes valve 54 
close and valve 50 open again. Water discharge like this assures the 
continuous performance of container 31. 
(6) The work procedure of the device 
a) The preheat procedure of the device 
The input procedure, the gas bubble generating system and the vacuum 
exhaust system begin to work at the same time, when the oil surface 
reaches the upper level surface controller 55, valve 64 opens, at the same 
time valves 37 and 63 close, and the output procedure simultaneously 
begins to work. In this interval, the device enters into the work state of 
cycle preheating. 
b) Work procedure of normal performance 
When the temperature of the vacuum container is near that of the oil, 
valves 37 and 63 open while valve 64 closes. At this time, if the upper 
liquid surface controller is in the state of being triggered, the flow 
rate of valve is increased. If the lower liquid surface controller is in 
the state of being. triggered, the flow rate of valve 61 decreases, 
slightly making the input and output flow rate to match each other. It is 
at this period that normal operation is reached. 
The device of this invention characterized in that: 
1) As there are no spray parts and fillers in this device, no strict demand 
is required for the viscosity of the oil, it has greater applicability. 
2) As there are no spray parts, there is no clogging of materials and other 
easily damaged parts. Therefore maintenance is easy. 
3) If the definition 
##EQU1## 
is taken to describe the oil/water separation performance of the device, 
the .beta. value of this device can not only be decided at the time of 
design, but also the range of .beta. value to be regulated is very large 
for designing finalized device 
4) For oil with high viscosity and high water content, the average .beta. 
value of the conventional spray plus filler method is only between 1.2 to 
3, while that of the device of this invention can reach 20-100, or even 
higher. 
5) For oil with high viscosity and high water content, only one treatment 
by the device of this invention can arrive at the stipulated purity 
standard, there is no necessity to recycle a number times and to take a 
long time to reach the purity standard. 
6) The noises made by the single-chamber type intermittent treatment low 
vacuum oil purification device is far lower than those made by the 
conventional devices. 
7) In the multi-chamber type continuous treatment low vacuum oil 
purification device, as passing the oil mixture liquid only once through 
the device can reach the purity standard, and the purification can be 
carried out continuously, the device can easily be connected onto the 
production assembly line of oil-production or oil purification/refinement. 
With the other conventional devices, many recycles are necessary to arrive 
at the purity standard, thus it is difficult for them to be connected onto 
the production assembly line. 
8) The inventor adopted an experimental low vacuum oil purification device 
similar to the single-chamber type intermittent treatment device as shown 
in FIG. 1. Hydraulic oil, the water content of which was 10,000 ppm, was 
being treated after being completely emulsified for oil/water separation 
in the device. Half an hour later, the water content in oil was lowered to 
88 ppm and the .beta. value was 113. Among the more advanced devices in 
the prior art, for hydraulic oil with 10,000 ppm water content, 4-6 
recycle treatments were carried out during the time interval of around two 
hours, and the water content was only lowered to 500 ppm. If four recycles 
were taken into consideration, the value was 2.12. The ratio of the two 
.beta. values was over 50 times. 
This fully explains the superiority and the active effects of this 
invention.