This invention relates to oil-water separation technique, specifically, a system for automatically separating and recovering oil from bilge water.
Treatment of oily wastewater generated by cruise ships has been regarded as one of worldwide challenges for eco-environmental protection for centuries. In general, oil spill pollution can be divided into three types: that caused by maritime transportation, that caused by coastal industrial activity and that occurs on inland water areas. Oil spill pollution occurring on inland water areas (including rivers and lakes) refers to the pollution of the inland water areas resulting from direct dumping of the untreated bilge water generated in the engine room of the cruise ships. This kind of pollution has engendered severe negative impact upon the fragile eco-system of inland waters in China. The negative effect has emerged in Dianchi Lake, Yunnan Province, China, and currently all diesel-engined ships are banned to enter the lake by local authority. The pollution caused by the same reason also occurred in the Three Gorges area of the Yangtze River. Besides, in July of 2007, Nanjing Maritime Agency (of Jiangsu Province, China) stipulated that drain outlets of all ships cruising in Nanjing reach of the Yangtze River should be closed. However, this method cannot solve the oil spill pollution once and for all. In China, the huge number of diesel-engined ships will definitely produce much bilge water. If effective methods are not adopted in treating the bilge water, it would pollute inland waters in one way or another even though the direct dumping is prohibited. Therefore, the crucial strategy of dealing with the wastewater pollution is to find an effective way for treating the bilge water. The characteristics of the bilge water requires special treatment: first, the oil content at different levels of the bilge water changes so greatly that it varies from several mg/L at the lower level to several hundred mg/L at the upper level. This consequently increases the difficulty of treatment. Second, engine rooms of most ships are spatially compact. The oil separation apparatus should be small and highly effective. Third, all ships work in the state of movement. Therefore, the oil separation apparatus should be designed with high and stable working performance in the state of tossing and pitching. The apparatus in this invention is the very device designed for treatment of bilge water generated by cruise ships (for both maritime and inland water transportation). Fourth, according to Resolution MEPC.107(49) stipulated by International Maritime Organization—“Revised guidelines and specifications for pollution prevention equipment for machinery space bilges of ships”—the anti-pollution apparatus should be capable to tolerate the passage of 100% concentration of specific oil medium for five minutes while no harm occurs to the apparatus itself. This special requirement poses a demanding challenge for the design of the anti-pollution apparatus of this kind.
This invention relates to an automatic oil-water separation and recovery system designed for synchronic treatment of the bilge water generated during cruise. It is the further development of the China patent “Automatic Oil-water Separation and Recovery Device” (Patent No. CN200510040609.2).
The technical art of this invention includes:
An automatic oil-water separation and recovery system used on ships, comprising three cylindrical tanks A (1), B (2) and C (3). The top of each tank has an oil collector (4, 5, 6) that opens into the respective tank and can recover the oil from the wastewater. There is an inflow pipe (20) at the top of tank A (1). The untreated wastewater is led into tank A (1) through the inflow pipe (20). It streams down to the lower part of the tank through the pre-separation regulating water distributor (10) that links to the inflow pipe (20) at the top of tank A (1). The water distributor (10) is in the shape of an obconic bell mouth, whose lower mouth is linked to the inflow pipe (20). The lower part of tank A is equipped with an outflow collector (16), upon which a bar-shaped oil-water separation unit (13) is attached. This unit (13) is firstly wrapped with the nonwoven cloth made from HK oil-resistant material (35), then taped with wires made from the same material (34), and further wrapped with the nonwoven cloth made from the same material (36). (the above-mentioned HK oil-resistant material is manufactured by Nanjing Greenshield Environmental Equipments Co., Ltd.) The outflow collector (16) of tank A (1) has an outlet (24), which links to the inflow pipe (21) of tank B (2) and the pre-separation regulating water distributor (11) at the top of tank B (2). The water having been treated in tank A (1) is channeled to the water distributor (11) in tank B (2); it then streams down through the water distributor (11) to the filter (14) equipped at the lower part of tank B (2). The filter (14) is filled with active carbon (grain size: 14-18 eyes). The water is therefore further treated by the filter (14), and then through the outflow collector (17) at the lower part of tank B (2) is channeled by the inflow pipe (22) to the pre-separation regulating water distributor (12) at the top of tank C (3). The bar-shaped oil-water separation unit (15) equipped upon the outflow collector (18) at the lower part of tank C (3) is made by the same method as the said unit (13) in tank A (1). The water that has been twice treated now receives a third purification, and streams to the outlet (26) through the outflow collector (18) of tank C (3). It is then channeled into the water tank of the cooling system and used as cooling water for the ship's engine set. The bar-shaped oil-water separation unit (13), as said above, is made up of a rigid, antipriming pipe firstly wrapped with nonwoven cloth made from highly hydrophilic and oil-resistant material, then taped with wires made from the same material, and further wrapped with nonwoven cloth made from the same material.
In the above-mentioned oil-water separation and recovery system, the pre-separation regulating water distributors in the three tanks are all in the same design. The water distributors contain an obconic bell mouth that are characteristic with concentric screw slots on the inner wall.
The operating mechanism of the automatic oil-water separation and recovery system described in this invention works as follow:
When the wastewater accumulates to a certain height in the engine room, it is pumped (manually or automatically) into a separate filter filled with active carbon in order that some floating oil and other float solid grains can be removed. Then, the water is led to the pre-separation regulating water distributor (10) in tank A (1). After preliminary separation in the water distributor, the separated oil is recovered by the oil collector at the top of the tank. The wastewater after preliminary separation, driven by the pump, goes through the bar-shaped oil-water separation unit (13) at the lower part of tank A. Oil in the wastewater is filtered outside of the unit and will be automatically sent to the oil collector at the top of the tank and recovered.
The wastewater having been treated in tank A is channeled into the pre-separation regulating water distributor (11) at the top of tank B, then spills down to the filter unit (14) made of active carbon, wherein the remaining emulsified oildrops in the wastewater will be removed.
Thereafter, the water is led through the outlet of tank B to the pre-separation regulating water distributor (12) at the top of tank C. with the same method as that in tank A, oil in the wastewater will be filtered outside of the bar-shape oil separation unit (15), and automatically sent to the oil collector at the top of the tank and recovered. After oil-water separation process conducted by the unit (15) in tank C, the oil content in the wastewater is lower than 5.0 mg/L. In addition, the water after treatment is channeled to the water tank of the cooling system of the engine set. Therefore, both oil and water are recovered.
The introduction of pre-separation regulating water distributors to this oil-water separation system structurally ensures the high-gradient decrease of flow speed of wastewater when the flow diameter experiences an abrupt enlargement, which consequently facilitates coagulation of oil droplets. Furthermore, the existence of concentric screw slots on the inner wall of water distributors ensures that oil in the wastewater stays on the surface and flows towards the brim of water distributors while water in the wastewater stays at the lower part of the water distributors and flows along the normal line of slots. The different flowing modes between oil and water engender speed difference plus, which, in combination with the concentration difference between oil and water, can improve the effect of oil-water separation. The equipment of the water distributors can also effectively control cross turbulence caused by tossing of the ship.
Small size and light weight are characteristic of this automatic oil-water separation and recovery system. The system displays excellent performance during treating bilge water that contains different oil content, and the oil content after treatment is about or lower than 5.0 mg/L. Water with such low oil content can be reused as cooling water for the ship, which definitely saves the fresh-water that is particularly precious during maritime cruise. The whole system shows stable performance during operation.
The automatic oil-water separation and recovery system described in this invention can also be employed in treatment of oil spill accidents that occur in maritime transportation. Not only can it lower down the environmental damage, but also it can efficiently recover spilt oil.
In the said figures: 1 tank A; 2 tank B; 3 tank C; 4 oil collector of tank A; 5 oil collector of tank B; 6 oil collector of tank C; 7 oil recovery pipe of tank A; 8 oil recovery pipe of tank B; 9 oil recovery pipe of tank C; 10 pre-separation regulating water distributor of tank A; 11 pre-separation regulating water distributor of tank B; 12 pre-separation regulating water distributor of tank C; 13 HK oil-water separation unit of tank A; 14 active carbon filter unit of tank B; 15 HK oil-water separation unit of tank C; 16 outflow collector of tank A; 17 outflow collector of tank B; 18 outflow collector of tank C; 19 pump; 20 inflow pipe for bilge water (untreated water); 21 inflow pipe of tank B; 22 inflow pipe of tank C; 23 flow meter; 24 outlet of tank A; 25 outlet of tank B; 26 outlet of tank C; 27 drain outlet; 28 water pressure gauge; 29 control box; 30 filtering bar sintered by active carbon
An automatic oil-water separation and recovery system, as illustrated in
Insofar as the system illustrated in Embodiment 1 is adopted, the oil content in the untreated water and the treated water is indicated respectively in the following (when the inflow speed is 200 L/h):
An automatic oil-water separation and recovery system, sharing the same general structure as that above-mentioned in Embodiment 1. The differences are: the diameter of the lower mouths of the pre-separation regulating water distributors (10, 11, 12) changes to 26 mm, and the vector height of which changes to 30 mm.
Insofar as the system illustrated in Embodiment 2 is adopted, the oil content in the untreated water and the treated water is indicated respectively in the following (when the inflow speed is 500 L/h):
An automatic oil-water separation and recovery system, sharing the same general structure as that above-mentioned in Embodiment 1. The differences are: the diameter of the lower mouths of the pre-separation regulating water distributors (10, 11, 12) changes to 20 mm, and the vector height of which changes to 30 mm.
Insofar as the system illustrated in Embodiment 3 is adopted, the oil content in the untreated water and the treated water is indicated respectively in the following (when the inflow speed is 400 L/h):
An automatic oil-water separation and recovery system, sharing the same general structure as that above-mentioned in Embodiment 1. The differences are: the diameter of the lower mouths of the pre-separation regulating water distributors (10, 11, 12) changes to 20 mm, and the vector height of which changes to 35 mm.
Insofar as the system illustrated in Embodiment 4 is adopted, the oil content in the untreated water and the treated water is indicated respectively in the following (when the inflow speed is 200 L/h):
An automatic oil-water separation and recovery system, sharing the same general structure as that above-mentioned in Embodiment 1. The oil content in the untreated water and the treated water was tested by an authoritative environmental monitoring organization—Jiangsu Environmental Monitoring Center. The result was shown as follow (when the inflow speed was 200 L/h and oil content in the untreated water was low):
An automatic oil-water separation and recovery system, sharing the same general structure as that above-mentioned in Embodiment 1 and Embodiment 5. The difference is that the oil content in the untreated bilge water is higher than that in Embodiment 5. The oil content in the untreated water and the treated water was tested by an authoritative environmental monitoring organization—Jiangsu Environmental Monitoring Center. The result was shown as follow (when the inflow speed was 200 L/h and oil content in the untreated water was high):
Number | Date | Country | Kind |
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200710020574.5 | Mar 2007 | CN | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CN2008/000424 | 3/3/2008 | WO | 00 | 6/1/2009 |