Patent Application
20140291261
The present disclosure relates to filtration of fluids, such as seawater, which may be stored in ballast tanks aboard a seagoing vessel. Filtrations systems are provided onboard seagoing vessels equipped with ballast tanks to prevent entrance of unwanted inorganic material and organic species into the ballast tanks. This has been found particularly necessary where seagoing vessels transit bodies of fresh water before entering port such that discharge of seawater into the fresh water does not transport unwanted organic marine life into the fresh water.
Where such filtration systems have been employed for seawater ballasts, a pressure vessel having disposed therein a plurality of replaceable filter media elements has been employed. Heretofore, the pressure vessel has been provided with a backwashing system which permitted the individual filter media elements to be backwashed sequentially without interrupting filtration flow through the remaining filter media elements. An example of a known seawater filtering system 10 is shown in
Referring to
When the ballast tanks have been filled, the backwashing cycle may be continued until completed. However, as only one filter media element is backwashed for a given position of the backwash arm, the remaining filter media elements will continue to be caked with retained foreign material including organic species. Thus, it has been desired to provide a way or means of minimizing the accumulation of filtered material on the filter media elements during the backwash sequence.
The present disclosure provides a filtering system for filling and emptying seawater ballast tanks and includes a filtration system for unified filter vessel having a multiplicity of individual filter media elements for filtering seawater entering the ballast tanks. The unified filter vessel includes a backwashing function for sequentially backwashing each of the filter media elements while permitting flow of filtrate through the remaining elements to the ballast tank. The filtration system of the present disclosure includes a recycle line connecting filtrate flow from the unified pressure vessel to the inlet of the pumps supplying seawater to the unified filter vessel. This arrangement minimizes the flow of raw seawater to the filter media elements during the backwashing sequence and, thus, provides cleaner fluid for performing the backwashing.
Referring to
The pump outlet is connected through a line 112 and through another valve 114 to the inlet line 116 of a unified filter vessel indicated generally at 118; and, it will be understood that the unified filter vessel 118 may be similar to the filter 14 of
The filtrate outlet of the unified filter vessel 118 flows through outlet line 120 and through a flow meter 122 and through line 124 and another valve 126, the outlet of which is connected to a line 128 for carrying filtrate to the inlet of an onboard ballast tank (not shown).
The backwash outlet line or drain line 130 of the filter vessel 118 is connected through another valve 132, the outlet of which is connected to a drain line 134 which may be an overboard drain.
The outlet line 112 of the pump 106, if desired, may also be connected through another valve 136, the outlet of which is connected to the overboard drain line 134.
The outlet of flow meter 122 through line 124 may also be connected through another valve 138 to the overboard drain line 134.
The outlet line 124 of the flow meter is also connected through a valve 140 to a recycle line 142 which is also connected to the inlet of the pump 106.
During the backwashing sequence of the unified filter vessel 118, typically when valve 126 is closed, valve 140 may be opened to provide a flow clean filtrate flow to the pump such that flow to the inlet of the pump comprises a mixture of seawater from valve 104 and clean filtrate from line 142 thereby minimizing the buildup or clogging of the remaining filter elements during the backwashing sequence.
The present disclosure thus describes a fluid filtration system and particularly for filling onboard seawater ballast tanks employing a unified filter pressure vessel having a multiplicity of individually replaceable filter media elements. The unified pressure vessel employed is of the type providing for sequentially backwashing of the individual filter elements and also provides for recycling of clean filtrate during the backwashing sequence to minimize buildup of foreign material on the filter media elements during the backwashing sequence.
Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary versions described herein be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
