Patent Grant
7198713
Not applicable.
Not applicable.
With the ballast water, ships take up the most heterogeneous animal and vegetal organisms, e.g. mussels, fish, worms, crabs, bacteria, viruses and so on, which they set free again in extraneous regions where these are not native. These organisms often can spread rapidly in their new environment, because natural enemies are lacking. Through this, big ecological and/or economical damages can be brought about.
Different methods to prevent release of organisms with the water in tanks are known, e.g. by filtration, heat treatment, by reverse osmosis or UV-irradiation. Further, it is known to chemically combat organisms in water. All the stated methods are insufficient when applied to ballast water, however. The ballast water is conveyed into the ballast tanks in a very short time with a very high speed or high volume, respectively. In doing so, it must be ensured that the ballast water has been made aseptic to a large extent in this relatively short period of time.
The invention has the objective to create an installation for the removal and the deactivation of animal or vegetal organisms in the ballast water, which fullfills the security standards upon filling or clearance of the tanks with sparsely sumptuous means. Further, the installation according to the invention should bring about little expenditure in apparatus and should also be susceptible to be backfitted in a simple manner, e.g. on ships.
The installation according to the invention consists of at least two components. One of them has a gravity precipitation, e.g. a group of hydrocyclones which are parallel connected, a control equipment providing that only as much hydrocylones are in operation as is needed. As is generally known, hydrocyclones have only a restricted range of operation. That is why a control equipment switches the hydrocyclones on or off, in accordance with the conveying volume. The hydrocyclones do not only significantly reduce the sediment load carried along with the water, but they also remove a great deal of bigger organisms, in a dimension of more than 300 μm, e.g. The hydrocyclones are dimensioned such that these organisms can be efficiently separated, even when their specific weight is only faintly larger than 1.
A peculiarity of the hydrocyclones is that an arbitrary number can be connected together, in order to adjust them to any arbitrary quantity passing through, within the framework of their operating optimum. Hydrocyclones have also the advantage that they are almost maintenance-free and operationally reliable. They are insensitive against occlusions and can be simply and quickly attended, as the case may be. According to one form of the invention, they have a wear-resisting, corrosion-proof surface, e.g. in the form of a coating. Through this, the inner walls are protected against abrasive and corrosive strains.
The first feed pump is preferably a rotatory pump, as is usually in operation as a ballast water pump, e.g.
According to a further form of the invention, the underflow of the hydrocyclones is connected to a second feed pump, to which a first regulating equipment is associated which measures the conveying volume in the underflow duct and conveys a predetermined constant volume flow, dependent on the number of switched-on hydrocyclones. This measure stabilises the operation of the hydrocyclones. The second feed pump, which is preferably a positive-displacement pump, is switchable in steps of constant conveying volume, each step being adjusted to a predetermined number of hydrocyclones which are in operation. Alternatively, it is conceivable to associate one downstream conveying pump to each underflow of at least a part of the cyclones.
It is also conceivable to envision another gravity precipitation, e.g. a centrifuge or the like. It is further conceivable to omit gravity precipitation and to provide a suitable filtration equipment instead. The filtration equipment has to be dimensioned such that even coarser particles can be deposited without problems.
According to another form of the invention, a control valve is disposed in the duct to the filtration equipment, to which a second regulating equipment is associated, which maintains a predetermined pressure in the upstream side duct by regulating the opening area of the control valve. This measure serves also for the stable operation of the hydrocyclones, which becomes particularly effective in the backwash mode of operation of the filter. As is generally known, the pressure on the filter decreases significantly during the backwash mode of operation. Anyhow, the operation of the hydrocyclones has to be maintained.
A filtration equipment, arranged downstream to the gravity precipitation, serves for the fine filtration and by doing so for the deposition of parts and germs with smaller dimensions, e.g. in the range of 300 μm to 50 μm. As the case may be, organisms which can not be deposited with the filtration equipment because of their geometry and extent are damaged such that they are easily amenable to a chemical or other further treatment step. Particularly advantageous is the use of a filtration equipment as has become known from DE 4312731. Each filter cartridge of a filtration equipment having several filter cartridges has a layer of overlayed elements of elastically deformable material, two neighbouring elements of which form a flowable gap, respectively. Each element has a lip on its input flow side, which is directed towards the flow with its broad front plane and is elastically displaceable and elastically deformable in the flow direction, the opening edge of which forms the gap opening, together with the opposing fixed opening edge of the neighbouring element. A particle entering in a jamming manner in the gap opening with the flow exercises an entraining force upon the opening edge of the lip, thus narrowing the gap opening.
In the described backwash filter, the purified liquid coming from the hydrocyclones is directed against the outlet side of a filtering surface in the backwashing mode of operation, whilst the inlet side is connected to a backwashing pump in a backwashing branch. The backwashing mode of operation is preferably initiated when the filter is gradually becoming clogged. According to one form of the invention, this case is detected by a differential pressure measurement. When the differential pressure is a predetermined value, the backwashing mode of operation is initiated via the control equipment. The above-described adjustment in the upperflow and the underflow of the cylones provides for that the backwashing mode of operation has no nocuous effects on the operation of the hydrocyclones.
Organisms and germs that are in the water on the outlet side of the filtration equipment are rendered innocuous by the last component of the installation according to the invention, preferably by a chemical treatment with a means which preferably has a short time of degradation and is then biologically innocuous. The addition of a chemical, preferably a mixture of organic acids, like peroxyacetic acid, hydrogen peroxide and so forth, has the advantage that is does not only exert a desinfecting action when added to the water, but also thereafter in the tank, when the water is conveyed into a tank. As long as the water is in the tank, there is no danger of ecological damage. When the chemical is rapidly degraded, the ballast water can be passed after a short time into the sea, for instance, if that is required.
The supply of the chemical, preferably a biocide acting in a purely oxidative way, depends on the conveying volume, according to another form of the invention. It is to be understood that other treatment possibilities are conceivable besides the chemical treatment step, additionally or alternatively, like an UV-irradiation or the like, for instance.
The invention provides a dosage equipment for the application of the biocide, whereat according to a further form of the invention a pump for increasing the pressure is connected between the inlet point in the outlet duct of the filtration equipment and a point of the outlet duct upstream to it, and a dosage pump feeds the biocide into the outlet duct of the pump for increasing the pressure via a nozzle. In this bypass dosage, a partial flow is taken out of the filtered water and put under increased pressure. In the injection fitting, a biocide is metered into this pressurised water. As a result of this admixture, a premixing of the biocide with water takes already place. The premixed water is introduced into the mainstream, under conversion of the pressure energy into kinetic energy.
According to a further form of the invention, a static mixer is downstream side connected, which provides for an intimate mixing of the microbiocide with the water that is to be treated. The described metered addition of the microbiocide takes place with very small pressure drops. Therefore it is not necessary to dimension the first feed pump such that an additional pressure drop has to be compensated.
The individual treatment steps have preferably a bypass, so that a flow of water is provided even at malfunction or fail of auxiliary energy, e.g. in order to be able to ensure the ship security. If e.g. the mechanical-physical treatment step fails, for instance through failure of the hydrocyclone step or the filtration equipment, then this failure can be compensated for, for instance by an automatically occurring increase of the dosage volume of the microbiocide, so that a treatment of the conveyed water is ensured in each case.
The installation according to the invention is planned such that it can be operated almost maintenance-free and that it ensures the highest operational reliability as possible. It is suited for new constructions and for backfitting as well. The outer dimensions of the whole installation can be geared to the room available, e.g. on ships. All components can get along with the conventional deck to ceiling height. The demand of electrical energy is relatively low.
The installation according to the invention is not restricted to its application to ships, but it can be also used for land-based installations, when a like or similar problem definition is present.
The invention is subsequently explained in more detail, by means of a realisation example represented in drawings.
While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated
The installation according to
The component C is concerned with the metered addition of a desinfectant. Subsequently, the individual components will be commented on in more detail.
A first feed pump 10, preferably a rotational pump, conveys via a stop valve 12 into a duct 14, which is in connection with six hydrocyclones 16.1 to 16.6, via stop valves 18.1 to 18.6. The upperflow of the hydrocyclones 16.1 to 16.6 is connected to a common duct 20. The underflow of the hydrocyclones 16.1 to 16.6 is connected to a common duct 22 via stop valves 24.1 to 24.6. The duct 22 is connected with a duct branch 26, in which a pressure gauge 28, a flow meter 30, a second feed pump 32 as well as a stop valve 34 are situated. The function of the described parts is dwelled on below.
The duct 20 is connected with a duct branch 36, in which a control valve 38 is disposed. Further, a pressure gauge 40 before the valve 38 and a flow meter 42 after the valve 38 are connected to the duct branch 36. Additional pressure gauges 44 and 46 are disposed before and after the flow meter 42.
A back-washable filtration equipment 50 is in connection with the branch 36 via a stop valve 48. A regulating fitting 54, a stop valve 56, a pressure gauge 58 and a flow meter 60 are connected to an outlet duct 52 of the filtration equipment 50. A stop valve 64 is disposed in a bypass duct 62, which is connected before the valve 48 and after the valve 56 with the inlet and the outlet of the filtration equipment 50, respectively.
In a suction duct 66, which is connected to the filtration equipment 50, a stop valve 68, a backwashing pump 70, a pressure gauge 72, a control valve 74 and an additional stop valve 76 are disposed.
A branch duct 78, which is connected to the branch outlet duct 52 immediately on the downstream side after the filtration equipment 50, contains a stop valve 80, a pump for increasing the pressure 82, a check valve 84, an injection nozzle 86 and a stop valve 88. On the downstream side of the flow meter 60, the branch duct 78 runs into the outlet duct 52, via an injection nozzle 90. On the downstream side of the injection nozzle 90, a static mixer 92 is disposed in the duct 52. On the downstream side of the static mixer 92, a pressure gauge 94 is connected to the outlet duct 52. The outlet duct 52 leads to a not shown tank, the ballast tank on a ship e.g.
A not shown control equipment controls the individual functions of the described parts and components, which furthermore contains a couple of control loops. Subsequently, the function of the installation according to
Upon open stop valves 12 and 18.1 to 18.6 and closed stop valve 96 in a bypass duct 98 for the hydrocyclones 16.1 to 16.6, the rotary pump 10 supplies sea water into the hydrocyclones 16.1 to 16.6. The underflow of the hydrocyclones 16.1 to 16.6 is connected to the duct 26, and the constant feed pump, preferably the positive displacement pump 32, conveys a constant volume from the underflow of the cyclones into the sea. However, the number of the actually switched-on hydrocyclones 16.1 to 16.6 depends on the required conveying volume, which may also be proportional to the pressure which can be measured on the downstream side of the pump 10 with the aid of the pressure gauge 100. When the ballast water tank is partially filled, the conveying volume enforcedly becomes smaller. As mentioned, the second feed pump 32 conveys a constant volume of water, the volume being dependent on the number of switched-on hydrocyclones 16.1 to 16.6, however. With the number of switched-on hydrocyclones 16.1 to 16.6 becoming bigger, the constant volume of water becomes stepwise larger. The flow meter 30 serves for the regulation of the conveying volume of the pump 32, which is predetermined by the number of cyclones in operation. It provides for that the conveying volume of the pump 32 remains constant, in dependence of the number of cyclones in operation.
Instead of one single second feed pump, it is also conceivable to connect a smaller pump to each underflow of a cyclone, in order to stabilise the operation of the cyclone.
A further control equipment is associated to the control valve 38, which provides for a constant pressure in the duct 20, via the pressure gauge 40. Through the adjustment of the pressure in the duct 20 and the conveying off of the underflow in a constant volume it is provided for the hydrocyclones 16.1 to 16.6 or for the switched-on cyclones to work under stable operating conditions.
In the filtration equipment 50, which is realised according to DE 4312731 e.g., organic components up to an extension of 50 μm are separated. The water, which is purified to a large extent, reaches the outlet duct 52, into which a desinfectant or a biocide is introduced via the nozzle arrangement 90.
The filtration equipment 50 is back-washable, and a differential pressure meter 102 measures the pressure on the inlet and on the outlet of the filtration equipment. When the differential pressure reaches a predetermined value, the back-wash operation mode is initiated. For this purpose, the regulation fitting 54 is set to the locking position by the control equipment. Further, the back-washing pump 70 is initiated, the stop valves 68 and 76 being open and the control valve 74 slowly opening itself. The water coming from the hydrocyclones serves for washing back the filter surfaces, and with this water, the filtrate comes back into the sea via the duct 66.
The filtration equipment 50 is back-washable, and a differential pressure meter 102 measures the pressure on the inlet and on the outlet of the filtration equipment. When the differential pressure reaches a predetermined value, the back-wash operation mode is initiated. For this purpose, the regulation fitting 54 is set to the locking position by the control equipment. Further, the back-washing pump 70 is initiated, the stop valves 68 and 76 being open and the control valve 74 slowly opening itself. The water coming from the hydrocyclones serves for washing back the filter surfaces, and with this water, the filtrate comes back into the sea via the duct 86.
The bypass duct 62 serves to shunt the filtration equipment 50, if any failure should take place. Through this, it is ensured that ballast water can be pumped into the ballast tank in this case also.
When the stop valve 80 is opened, the pump for increasing the pressure 82 branches off purified water which comes from the outlet duct 52 of the filtration equipment 50 and presses the water into the nozzle arrangement 90, the stop valve 80 being open. On the downstream side of the pump for increasing the pressure 82, there is an injection nozzle 86, which is connected to a dosage pump 106, which on its part aspirates biocide from a biocide container 108. In this way, a premixing of the biocide with water takes place already by the nozzle arrangement 86 and the nozzle arrangement 90. The complete mixing of the biocide with water takes place behind the nozzle arrangement 90, whereupon a further intense mixing takes place in the static mixer 92, which has a very low pressure drop. The pressure for the mixing is essentially furnished by the pump for increasing the pressure 82, so that the first feed pump 10 is not charged with this.
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It should be noted that the hydrocyclones 16.1 to 16.6 can be provided with a wear-resisting and corrosion-proof surface, a ceramic coating for instance, which decreases the frictional resistance and forms a resistance against abrasion and corrosion.
It should be further mentioned that a third control equipment controls the supply of microbiocide from the container 108 into the outlet duct 52, by measuring the volume flowing in the duct 52 by means of the volume flow measuring equipment 60, the dosage pump 106 thereat conveying the microbiocide in accordance to the measured volume.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.
Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.
This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.
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