JPH0567354B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to the treatment of oil-water mixtures such as oil-containing bilge water in ships or oil-containing factory wastewater. This invention relates to an oil-water separator that purifies water by separating it.

[Conventional technology]

In general, this type of oil/water separation equipment uses a flotation separation method, which uses the difference in specific gravity between water and oil to float and separate the oil on the water surface, and a flotation separation method, in which the oil-water mixture is passed through a filter and the oil is adsorbed by the filter. There is a filtration separation method that allows only water to pass through, but the former flotation separation method can only be applied when the oil particle size is relatively large, and the latter filtration separation method is There is a problem in that clogging occurs, especially when the oil in the oil/water mixture is emulsified by the presence of a surfactant, such as in bilge water on a ship. Because of the large diameter (several microns), it could not be separated by either the flotation separation method or the filtration separation method.

On the other hand, there is Utility Model Publication No. 57-5048 as a prior art for evaporative oil/water separators, but this prior art is aimed at separating water from oil to obtain water-free oil. The method is to heat the water-containing oil and then spray it from a spray nozzle into a vacuum chamber with a degree of vacuum of approximately 600 mmHg.The difference in vapor pressure between oil and water is used to evaporate only the water, and the water vapor is cooled. The oil is condensed in a container and the water-free oil is taken out from the outlet at the bottom.

[Problem that the invention seeks to solve]

However, in the case of oil-water mixtures such as oil-containing bilge water inside ships or oil-containing factory wastewater, the mixing ratio of water and oil is opposite to that of the water-containing oil handled by the prior art, and this oil-water mixture is Oil in a liquid is not a single component, but contains components with various vapor pressures, so when a large amount of water evaporates, some of the oil components with vapor pressures close to water evaporate at the same time. At the same time, the water vapor will be accompanied by oil mist. Therefore, the water after evaporation separation will be mixed with some oil that evaporated and accompanied the evaporation, and the amount of oil mixed into the water after evaporation separation is equal to the oil-water mixture. When the water in the liquid is evaporated in the evaporation chamber,
It is related to the amount of oil supplied or present within the evaporation chamber.

However, the prior art described above heats the oil-water mixture without performing any preliminary separation and supplies it to the evaporation chamber to evaporate the water in the oil-water mixture. Since it is designed to take out oil, a large amount of oil enters the evaporation chamber and a large amount of oil remains. Therefore, when an attempt is made to separate the oil-water mixture that is the object of the present invention using the prior art, when the water evaporates in the evaporation chamber, the amount of oil that evaporates simultaneously with the water increases, and the water vapor increases. Since the amount of oil mist that accompanies increases, there is a certain limit to the improvement of water quality after evaporative separation, and the water quality after separation cannot be improved any further.

The present invention improves the water quality after separation by reducing the amount of oil that enters the evaporation chamber and the amount of oil that stays in the evaporation chamber when an oil-water mixture is separated into oil and water by evaporation. However, it is an object of the present invention to provide an oil-water separator that is capable of reducing the oil concentration in water after separation to a standard value specified by law.

[Means for solving problems]

For this reason, the present invention provides an evaporative oil-water separator in which water in an oil-water mixture is separated by heating evaporation, in which an oil-water mixture is supplied to the oil-water mixture in a supply path to the evaporative oil-water separator. A floating oil-water separator is provided to float and separate the oil contained therein, while the oil-water mixture in the evaporative oil-water separator is
This is characterized in that the oil is refluxed to the floating oil/water separator.

[Action/effect of the invention]

In this way, by installing a floating oil-water separator that floats and separates the oil in the oil-water mixture in the supply path of the oil-water mixture to the evaporative oil-water separator, the oil-water mixture can be separated from the evaporative oil-water mixture. Before entering the evaporation chamber of the separation device, oil is floated and separated in a floating oil-water separator. In other words, oil is first removed from the oil-water mixture by flotation in a floating oil-water separator. Only the oil that cannot be separated and removed in this floating oil-water separator enters the evaporation chamber of the evaporative oil-water separator, so the amount of oil entering the evaporation chamber can be reduced, while the oil-water mixture in the evaporation chamber is By refluxing the oil to the oil-water separator, the amount of oil remaining in the evaporation chamber can be reduced.

On the other hand, the temperature of the oil-water mixture in the floating oil-water separator increases due to the oil-water mixture returned from the evaporative oil-water separator to the floating oil-water separator, and the difference in specific gravity between water and oil increases. In addition, the viscosity of water and oil is reduced and the floating speed of oil can be accelerated, so the floating separation performance of oil in a floating oil-water separator can be improved. In the evaporation chamber of the evaporative oil-water separator, the volume of water decreases due to evaporation of water and contains a large amount of precipitated oil, so some of the oil with small particle size floats to the surface in the floating oil-water separator. Since it is successively adsorbed by oil, the flotation separation performance of oil is further improved. This improvement in flotation separation performance makes it possible to further reduce the amount of oil entering the evaporation chamber of the evaporative oil-water separator.

Therefore, according to the present invention, when an oil-water mixture is evaporated and separated in an evaporative oil-water separator, the amount of oil entering the evaporation chamber of the evaporative oil-water separator and the amount of oil staying in the evaporation chamber are controlled by the evaporator. By both providing a floating oil-water separator in the supply path of the oil-water mixture to the oil-water separator, and returning the oil-water mixture in the evaporative oil-water separator to the floating oil-water separator. , can be reduced synergistically, so the amount of oil that evaporates simultaneously with the evaporation of water and the amount of oil mist that accompanies water vapor can be extremely reduced, and the quality of water after oil separation can be significantly improved.

In particular, when the oil/water mixture to be handled is bilge water on a ship, this bilge water contains salt,
The salt concentration increases due to concentration accompanying evaporation of water in the evaporative oil-water separator, and the oil-water mixture with high salt concentration is returned to the floating oil-water separator. In this case, as the difference in specific gravity between water and oil increases,
Since the salting-out effect comes into play, the oil flotation separation performance is further improved.

Further, according to the present invention, the temperature of the oil floated and separated in the floating oil-water separator increases due to the oil-water mixture returned from the evaporative oil-water separator, and the viscosity decreases. It also has the effect of making it easier to discharge the oil from the floating oil-water separator.

〔Example〕

The present invention will be explained below with reference to the drawings of the embodiments. In the drawings, reference numeral 1 indicates an evaporative oil-water system in which a lower evaporation chamber 3 and an upper condensation chamber 4 are formed in a casing 2 so as to communicate with each other via a passage 5. In the evaporation chamber 3, there is a heater 6 that indirectly heats the oil-water mixture in the evaporation chamber 3 using a heating medium such as hot water or steam, and in the condensation chamber 4, Each is provided with an indirect cooling type condenser 7 using seawater or the like as a refrigerant, and a passage 5 communicating between the evaporation chamber 3 and the condensation chamber 4 is made of a material such as polypropylene cotton for adsorbing oil. An adsorbent layer 8 is provided, and a vacuum generator 9 such as a water ejector or a vacuum pump is connected to the condensing chamber 5.

The oil/water mixture flowing into the evaporation chamber 3 from the oil/water mixture supply pipe 10 is heated by the heater 6 and evaporated, and when the evaporated vapor passes through the adsorbent layer 8, the oil content is absorbed into the adsorbent layer 8. By adsorption and separation, only water vapor enters the condensing chamber 4 and is condensed in the surface condenser 7, and is taken out from the bottom of the condensing chamber 4 through a water take-out pipe 11 with a drain pump 12.

In this case, the indirect heater 6 is the evaporation chamber 4.
Instead of being provided in the evaporation chamber 3, it may be provided in the oil-water mixture supply pipe 10, and as a condenser for evaporated steam, instead of the indirect cooling type condenser 7 of the embodiment, Direct contact condensers such as barometric condensers may also be used.

In the figure, reference numeral 13 indicates a floating oil-water separator, and the oil-water mixture sent from the bilge tank 14 through an oil-water mixture supply pipe 15 with a pump 16 is connected to an oil-water mixture supply port in the floating oil-water separator 13. When the oil-water mixture flows in the tangential direction from 17 and gently swirls along the inner wall surface in the annular chamber between it and the inner cylinder 18, sediments such as sludge in the oil-water mixture settle and separate at the bottom, and the sludge discharge pipe On the other hand, the oil in the oil-water mixture rises to the surface of the water due to the difference in specific gravity with the water, and when the oil accumulates to the position of the oil level detector 20 at the top, it flows into the oil discharge pipe 21. When the automatic oil drain valve 22 opens, the oil is discharged from the oil drain pipe 21 to the outside of the vessel.

The oil-water mixture in the floating oil-water separator 13 is
After the oil is secondarily separated by the purifying separator 23 in the inner cylinder 16, it is supplied from the pipe 24 to the evaporation chamber 3 in the evaporative oil-water separator 1 via the oil-water mixture supply pipe 10. .

Then, the unevaporated oil/water mixture in the evaporation chamber 3 is transferred to an oil/water mixture reflux passage 26 equipped with a pump 25.
The extracted oil-water mixture is returned to the floating oil-water separator 13 via the oil-water mixture supply pipe 15 (in this case, the refluxed oil-water mixture from the oil-water mixture reflux passage 26 is returned to the floating oil-water separator 13 via the oil-water mixture supply pipe 15). It may also be directly refluxed into the separator 13).

Due to this reflux, the oil in the evaporation chamber 3 flows out from the evaporation chamber 3 and the floating oil/water separator 13
Since the amount of oil remaining in the evaporation chamber 3 is reduced, the floating oil-water separator 1
This increases the temperature of the oil-water mixture in the tank.

In this case, from the evaporation chamber 3 to the floating oil-water separator 13
It is preferable that the amount of the oil-water mixture returned to the bilge tank 14 is set to about twice the amount of the oil-water mixture sent from the bilge tank 14 to the floating oil-water separator 13 via the oil-water mixture supply pipe 15 with the pump 16. On the water surface in the evaporation chamber 3, there is a lot of oil floating on the surface of the water in the evaporation chamber 3 due to the decrease in the volume of water due to water evaporation. Preferably, the mixed liquid is extracted in the overflow chamber 27 and then refluxed to the floating oil/water separator 13. In addition, floating oil-water separator 13
By providing a heater 28 for the supplied oil/water mixture as shown by the chain double-dashed line in the oil/water mixture supply piping 15 (this heater 28 may be provided in the floating oil/water separator 13), type oil water separator 13
The flotation separation performance can be further improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a vertical sectional front view, and FIG. 2 is a sectional view taken from the side of FIG. 1. 1... Evaporative oil/water separator, 2... Casing, 3... Evaporation chamber, 4... Condensation chamber, 5... Passage,
6... Heater, 7... Condenser, 8... Adsorbent layer,
9...Vacuum generator, 11...Water discharge pipe, 10,
15...Oil-water mixed liquid supply pipe, 13...Floating oil-water separator, 19...Sludge discharge pipe, 21...Oil discharge pipe, 26...Oil-water mixed liquid return passage.

Claims (1)

[Claims] 1. In an evaporative oil-water separator that separates water in an oil-water mixture by heating and evaporation, the oil in the oil-water mixture is floated in the oil-water mixture supply route to the evaporative oil-water separator. An evaporative oil-water separator, characterized in that a floating oil-water separator is provided, and the oil-water mixture in the evaporative oil-water separator is refluxed to the floating oil-water separator.