Abstract:
A filter installation and method, especially a seawater filter installation and method, includes at least one fluid line ( 18,20 ) for transporting a biological fluid, a filter device ( 54 ) mounted in the fluid line with at least one filter element ( 22 ) in a filter housing ( 10 ), and a device for biological decontamination. The device for biological decontamination contains active substances that can be introduced into the filter housing ( 10 ), such as inert gases or special metals, ensuring that toxic impurities cannot enter. The active substances used are ecofriendly unlike chemically produced fungicides and herbicides.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a filter installation, in particular a seawater filter installation with at least one fluid line through which a biologically contaminated fluid can be transported. A filter is interposed in this fluid line, and has at least one filter element in a filter housing with agents for biological decontamination. 
     BACKGROUND OF THE INVENTION 
     DE 20 2004 002 616 U1 discloses a generic water filter installation, a seawater filter installation in particular, comprising a water line as a fluid line and a filter connected between two line sections of the fluid line. Individual filter elements are provided with a filter surface located in the filter interior for filtering water. One line section forms a feed line to the filter for the water to be cleaned. The other line section forms a drain line for the filtered water. In the known solution, feeding and draining of the filter can be blocked relative to the water line with blocking means (valves). The filter interior can be heated by a heating means with the blocking means blocked to a setpoint temperature of more than 50° C., preferably approximately 60±5° C. for decontamination of the filter surface. Preferably, the filter is designed as a backflushing filter with a backflushing means for cleaning the filter surfaces in counterflow to the actual filtering direction. 
     Aboard ship, such as for example container ships, ballast water is pumped on board in a particular harbor or underway in certain waters to be able to equalize missing ship&#39;s ballast. Ballast equalization can be achieved while sailing for example by a decreasing amount of fuel and by taking on new seawater ballast and/or pumping seawater between the individual ballast chambers to level the ship. When a new harbor is being approached and ballast water is pumped out into the harbor basin to load the ship with new cargo, it cannot be precluded that living organisms taken aboard in the original harbor or underway will be discharged in the new port of call. Thus, in a type of biological tourism, foreign organisms become settled in the biotopes, where they in fact do not belong, with the result that they can displace native species to their complete extinction. This occurrence can lead to a serious environmental situation. In addition to viruses, fungi, algae, protozoa, and other microorganisms can also be transported at the same time in this way. However, tiny organisms can indeed also be transported at the same time, including mussels and the like. 
     With the known solution according to the German utility model, this biological contamination is controlled by heating all the parts located in the filter interior of the filter for a sufficient time interval to a high enough temperature, for example 60° C., to kill algae, microorganisms and other tiny organisms. With the corresponding backflushing process, the killed organisms are returned immediately to the original water and are not delivered into foreign water after a forthcoming voyage. By preference, the known solution calls for cleaning by superheated steam. As a result of the indicated high temperature and considering that salt water is heated, this decontamination is highly corrosive and leads to the corresponding corrosion damage, thus necessitating the use of expensive materials, such as duplex steels, titanium or the like. The known solution is biologically very compatible for the environment. In particular, no toxic contaminants are formed. Only temperature control for the heating means to be triggered and monitored is very complex, and requires correspondingly trained operators. 
     It had already been suggested in the prior art that the microorganisms in the filter fabrics of a filter be destroyed by oxidation technologies using UV radiation. Ozone, chlorine dioxide and other toxic contaminants are then formed which contraindicate industrial use. The described devices in the prior art need not be limited to seawater applications, but can fundamentally always be used wherever problems occur with respect to bacterial and organic contaminants, as can occur for example in water filtering in industrial facilities, such as power plants. 
     SUMMARY OF THE INVENTION 
     Objects of the present invention are to provide an improved filter installation and a method for its operation which, while being able to ensure highly effective decontamination of biological materials, are reliable even over long periods of use without forming toxic by-products and without possible corrosion being promoted, and guarantee effective, economical cleaning. 
     These objects are basically achieved by a filter installation and a method where the agents for biological contamination have active ingredients such as inert gases and special metals which can be placed in the filter housing. Toxic impurities cannot occur, and the active substances used, in contrast to chemically produced fungicides and herbicides, are environmentally compatible by their being found directly in nature in this way without harmful intermediate decomposition products. The indicated active substances according to the present invention are also chosen such that corrosion damage can be avoided. Especially when using special metals, effective corrosion protection can build up, even if the metals themselves specifically kill the indicated living organisms, including plant material. 
     In one preferred embodiment of the filter installation according to the present invention, the inert gas is nitrogen gas which can be taken from at least one storage bottle. Preferably, after completion of the actual filtration, the nitrogen can be flushed into the interior of the filter housing with the filter element. The inert gas nitrogen within the filter housing creates a dry, oxygen-free environment used to kill living organisms. This nitrogen gas can be very easily managed using devices. It is easily economically available worldwide as a refill gas, and effectively controls the danger of corrosion. Instead of nitrogen gas, the filter could optionally be flushed in a less desirable version with compressed air. Since compressed air is generally available aboard ship, its use however does not lead to an oxygen-free environment and thus it can be used only as an emergency measure. Preferably, the inert gas in the associatable storage bottle is provided with high pressure such that the filter housing can also be flushed empty if the filter housing is still filled with seawater of a definable pressure (ambient pressure). 
     In another preferred embodiment of the filter installation according to the present invention, in the filter housing copper is used as the special metal in the form of at least one sacrificial anode. Since copper occurs in the environment and is not environmentally harmful at a correspondingly high dilution by seawater, it is especially well suited for the indicated use, especially with respect to killing of the indicated living microorganisms. Due to the configuration as a sacrificial anode, the copper removal in this respect also counteracts the continually prevailing corrosion. In an especially space-saving manner, the sacrificial anode can be accommodated in the filter housing if it is part of the filter elements used. By integrating the copper sacrificial anode into the filter elements, the fluid flow behavior within the filter housing is not hindered. This arrangement benefits overall operation of the system in terms of energy. 
     In one especially preferred embodiment of the filter installation according to the present invention, the design ensures ordinary filtering operation and, at the same time, allows backflushing for some of the filter elements to be able to use the cleaned filter elements for new filtration operations. Preferably, the fluid outlet of the filter is provided with a triggerable check valve. In the fluid flow direction following in the fluid line, a non-return valve is used such that in the opened position the exterior is connected to the associatable fluid line. As a result of the fluid lines which are very long in ships and power plants, water hammers can be avoided with the check valve blocked by the ambient air being able to flow after into the fluid lines via the non-return valve. Air volumes which may form in this way in the fluid line can be used then in the opposite direction as a damping element if water hammers in operation of the system can be expected in the opposite direction. 
     In the method according to the present invention for operation of this filter installation, coarse contaminants are filtered out of biologically contaminated fluid supplied via a fluid line by the filter element in the filter housing of a filter with agents for biological decontamination of the fluid releasing active substances such as inert gases and/or metal. The filter installation according to the present invention can be operated as a seawater filter installation. It can also be used for water filtration in industrial facilities, such as power plants. Furthermore, applications are possible particularly when problems arise within fluids with bacterial and/or organic impurities. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings which form a part of this disclosure: 
         FIG. 1  is a schematic, not to scale, side elevational view partially in section, of one embodiment of a filter installation according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The filter installation shown in  FIG. 1  is designed as a backflushing device and has a cylindrical filter housing  10  with two sealing covers  12 ,  14  attached to the filter housing  10  by flange connections  16 . The filter housing  10  of the backflushing filter device has one filter inlet  18  for the fluid to be filtered and one filter outlet  20  for the filtered fluid. Both the filter inlet  18  and the filter outlet  20  are parts of a fluid line which can run or extend over very long distances, for example in the cargo space of a container ship (not shown). The fluid direction in filter operation is symbolized in the FIGURE with the corresponding arrows  21  at the filter inlet  18  and at the filter outlet  20 . 
     Filter elements  22  tapering towards the top are inserted into the filter device. At least partially cylindrical filter elements (not shown) can replace the conical filter elements  22 . The conical filter elements  22  are preferably made as tubular, wedge wire screen filter elements, and are configured at distances from one another along a cylindrical (concentric) arc within the filter housing  10 . For an embodiment (not shown), the filter elements  22  can be configured divided repeatedly into groups along cylindrical arcs. Conical filter elements have the advantage that they allow uniform through-flow, with the result of low pressure loss, and enable complete cleaning of the elements in the backflushing cycle. 
     The filter elements  22  shown in the FIGURE open with their inlet cross section  24 , that is, with their free openings, into recesses of the lower sealing cover  14  made correspondingly cylindrical. On their opposite ends, the filter elements  22  are provided with sealing caps  26  via which the filter elements  22  are held on a plate-shaped intermediate piece  28  abutted by the upper sealing cover  12  from its top. 
     For actual backflushing with the backflushing filter device, a drivable flushing arm  30 , on its underside, provides a connection in the form of a fluid outlet  32  for fouled fluid. The flushing arm  30  can be moved via a drive rod  34  in succession to under the inlet cross sections  24  of the filter elements  22 . Backflushing therefore takes place continuously with the actual filtration process. One filter element  22  is backflushed, from the outside to the inside, with the cleaned, filtered fluid which forms in filtration with the other filter elements  22 . The flushing arm  30  extends in succession under the free inlet cross sections  24  of each filter element. The backflushing direction is indicated in the FIGURE with arrows  35  from the outside to the inside. The conventional filtration direction analogously is shown with arrows  35   a , from the inside to the outside. If the filter elements  22  grouped along cylindrical or concentric arcs are configured repeatedly within the filter housing  10 , the flushing arm  30  requires another arm section of different length (not shown), which can then extend under the other group of filter elements  22  on the side of their respective inlet cross section  24 . 
     The discharge of the fluid fouled in this way and forming during backflushing proceeds via the tubular fluid outlet  32 . The drive rod  34  extends through the filter housing  10  along the longitudinal axis  36  of the backflushing device and through both the upper sealing cover  12  and the lower sealing cover  14 . For driving of the drive rod  34 , especially in the form of a hollow shaft, on the upper sealing cover  12 , a spline shaft connection (not shown) drives the drive rod  34  with an electric motor  38  to rotate around the longitudinal axis  36 . The filter inlet  18  is formed in terms of its outside wall in the form of a diffuser which reduces the fluid inlet speed of the fouled fluid to be filtered with a simultaneous pressure increase on the inlet cross sections  24  of the conical elements  22  left open by the flushing arm  30 . The diffuser action is promoted especially by the inlet cross sections at the filter inlet  18  and the cross section of the receiving space  40  being made essentially the same. The transition between the filter inlet  18  and the receiving space  40  takes place essentially uniformly, without a reduction in cross section. 
     The conical structure of the filter elements  22  creates a passage surface in each filter element that is very large. The distance between adjacent conical elements  22  increases in the direction of the filter outlet  20  from the inlet so that a smaller resistance is offered to the filtered fluid upon emergence from the interior of the respective filter element  22 , compared to known solutions with exclusively cylindrical elements. Furthermore, the conical structure of the filter elements  32  yields a constant liquid flow when the elements are being backflushed. The fluid outlet  32  can be blocked by a controllable check valve  42 . Following or downstream in the fluid flow direction in another fluid line  44 , a spring-loaded non-return valve  46  acts with a closing ball which points toward the exterior  48 , and is held spring-loaded in this way in the closed position. If the check valve  42  is closed and a water hammer situation occurs due to the other fluid line  44  which is made long, the spring-loaded non-return valve  46  can open and, in this way, can produce an air-guiding connection between the exterior  48  and the interior of the fluid line  44 . In this way, the check valve  42  is relieved of replenishing processes within the other fluid line  44 . In the reverse case, that is, for fluid pressure loading in the direction of the check valve  42 , the non-return valve  46  effects a spring-loaded closure of the connection between the exterior  48  and the fluid line  44 . The air volume enclosed for example in the fluid line  44  forms a damper element which likewise relieves the check valve  42  in the closed state and subsequent system parts of the filter against water hammers. Preferably, the filter installation can be mounted upright by base legs  50  above the floor of the hall or deck  52  of the ship. 
     The filter  54  in the FIGURE can be connected to a storage bottle  56  which can likewise be mounted upright above the floor or deck  52  and which preferably holds nitrogen gas as the inert gas under high pressure. Via a pressure reducer  58  and via a solenoid valve  60  which can be triggered from the outside, the interior of the storage bottle  56  can be connected via a connecting line  62  to the filter  54  by one free end of the connecting line  62  extending through the sealing cover  12  and thus establishing a connection or fluid communication to the interior of the filter housing  10 . Furthermore, at least for some of the filter elements  22 , a sacrificial anode  64  made as a copper rod runs and extends concentrically in their interior and in their longitudinal directions. This sacrificial anode  64  is preferably made as a solid rod, and is releasably connected via a screw connection (not shown) to the upper sealing cap  26  of the respective filter elements  22 . By permanent release of copper, the sacrificial anode  64  is used up so that from time to time a new sacrificial anode  64  must be installed. This replacement can optionally take place with replacement of a used filter element  22  as a whole. 
     For the sake of better understanding, the filter installation will be described below using a seawater application. After opening the corresponding sea valves (not shown) on the ship&#39;s hull, seawater, generally fouled harbor water, flows via the filter inlet  18  into the filter  54 , and the individual filter elements  22  in the directions of the arrows  35  to clean the fouled harbor water. The cleaned seawater can be supplied in the direction of the arrow  21  via the filter outlet  20  to ballast tanks in the ship&#39;s hull (not shown). At the same time, this cleaned seawater from the filter elements not connected to flushing arm  30  is used simultaneously to clean the fouled filter elements  22  connected to flushing arm  30  during filtration operation in the opposite direction of the arrows  35 . This fouled backflushing liquid travels back to the exterior via the other fluid line  44  with the check valve  44  opened and the sea valves opened accordingly. In this conventional filtration operation, it cannot be precluded that the filter elements  22  become at least partially clogged with biological material such as microorganisms. They have ideal growth conditions, especially in voyages, in warm waters to spread further within the filter  54 . If the filter  54  is restarted in other waters, that is, in a foreign harbor or on the open sea, this restarting would lead to the biologically entrained material being flushed out resulting in the indicated microorganisms entering into the foreign biotope. 
     To prevent this occurrence, according to the present invention, while still in the original harbor or at sites of conventional seawater filtration operation, the filter  54  as such is shut down. After opening the solenoid valve  60 , nitrogen gas from the storage bottle  56  penetrates via the pressure reduction valve  58  into the interior of the filter housing  10 . Residual seawater fluid in the filter housing  10  is displaced by the high nitrogen pressure out of the interior of the filter housing  10  so that the filter elements  22  held in the filter housing  10  are completely flushed by the nitrogen gas. Thus, within the filter housing  10  an extremely dry, oxygen-free environment is created. This environment kills microorganisms, also in the form of plant material, which may have entered. If the filter installation is restarted elsewhere, there is no danger of unintentional discharge of foreign organisms. In addition to or instead of inert gas supply, the sacrificial anode  64  can also be used as the active substance. It is composed preferably of a metal material which is toxic, especially fatal to microorganisms. It has been shown that especially with respect to the desired corrosion protection, sacrificial anodes  64  of copper can be advantageously used. 
     With the present invention, not only is a filter installation created, with which conventional filtration tasks for elimination of contamination, especially in seawater, can be performed, but with which it is also possible to kill biological material with a simultaneous increase of corrosion protection. The filter installation according to the present invention manages with few standard components, so that the cost for implementing the filter installation is reduced. Furthermore, reliable use takes place due to the standard components. The filter installation can be used wherever fluid media must be filtered and wherever microbial burdens which are not desirable can be expected. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.