Fresh water marine flushing system and method

Abstract

A system and method for controllably connecting a marine vessel's native fresh water network to its raw water network in order to flush the raw water network. The controllable connection is provided by a hydrostatic lock-which ensures that water can only flow in the direction from the fresh water network to the raw water network and never in the opposite direction. A system controller directs the fresh water flush cycle and other operations.

1 . In a vessel having a fresh water tank, a raw water inlet, an engine, a raw water pump driven by said engine, a heat exchanger for transferring heat from said engine, and a raw water network for conveying raw water from said raw water inlet through said raw water pump and through said heat exchanger to a raw water outlet, a method for reducing the salinity of water contained within said raw water network, comprising:
 (a) providing a salinity sensor in said raw water network;   (b) providing a pump drawing fresh water from said fresh water tank and delivering it to a hydrostatic lock feed line;   (c) providing a raw water network connection between a hydrostatic lock outlet line and said raw water network;   (d) providing a hydrostatic lock, including,
 (i) a fresh water flush valve connected to said hydrostatic lock feed line and having a closed position and an open position, said fresh water flush valve being normally closed, 
 (ii) a check valve located between said fresh water flush valve and said hydrostatic lock outlet line, said check valve allowing flow from said fresh water flush valve to said hydrostatic lock outlet line but preventing flow in an opposite direction; 
   (e) providing a swing gate valve proximate said raw water inlet, said swing gate valve being configured to close when a first pressure within said raw water network exceeds a second pressure in said raw water inlet;   (f) while said engine is running and said raw water pump is operating, energizing said pump to create a suitable positive pressure across said hydrostatic lock, said suitable positive pressure exceeding said second pressure;   (g) opening said fresh water flush valve, thereby allowing fresh water to flow through said hydrostatic lock and into said raw water network, said resulting pressure in said raw water network being sufficient to close said swing gate valve;   (h) while a salinity measured by said salinity sensor remains above a defined threshold, holding said fresh water flush valve open and continuing to energize said pump; and
 (i) when said salinity measured by said salinity sensor falls below said defined threshold, closing said fresh water flush valve and shutting off said pump. 
   
     
     
         2 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 1 , comprising:
 (a) maintaining said engine in a running state; and   (b) when said salinity measured by said salinity sensor falls below said defined threshold, shutting off said engine   
     
     
         3 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 1 , comprising:
 (a) providing a system controller including a processor running software retrieved from a memory;   (b) said system controller controlling said fresh water flush valve and said pump;   (c) said system controller monitoring said salinity sensor; and   (d) said system controller executing said steps of closing said fresh water flush valve and shutting off said pump when said salinity measured by said salinity sensor falls below said defined threshold,   
     
     
         4 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 2 , comprising:
 (a) providing a system controller including a processor running software retrieved from a memory;   (b) said system controller controlling said fresh water flush valve, said pump, and a run state of said engine;   (c) said system controller monitoring said salinity sensor; and   (d) said system controller executing said steps of closing said fresh water flush valve, shutting off said pump, and shutting down said engine when said salinity measured by said salinity sensor falls below said defined threshold.   
     
     
         5 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 1 , wherein said salinity sensor is located proximate said raw water outlet. 
     
     
         6 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 1 , wherein said salinity sensor is located proximate a point where said raw water is fed into an exhaust stream from said engine. 
     
     
         7 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 1 , wherein said pump is a native fresh water pump within said vessel. 
     
     
         8 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 4 , comprising:
 (a) said system controller detecting when a user is shutting down said engine; and   (b) said system controller thereafter maintaining said engine in said run state while said system controller energizes said pump and opens said freshwater flush valve.   
     
     
         9 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 8 , comprising said system controller maintaining said engine in said run state until said salinity measured by said salinity sensor falls below said defined threshold, and thereafter shutting down said engine. 
     
     
         10 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 9 , wherein said system controller continues to energize said pump and hold open said fresh water flush valve for an interval of time after shutting down said engine. 
     
     
         11 . In a vessel having a fresh water tank, a raw water inlet, an engine, a raw water pump, a heat exchanger for transferring heat from said engine, and a raw water network for conveying raw water from said raw water inlet through said raw water pump and through said heat exchanger to a raw water outlet, a method for reducing the salinity of water contained within said raw water network, comprising:
 (a) providing a salinity sensor in said raw water network;   (b) providing a pump drawing fresh water from said fresh water tank and delivering it to a hydrostatic lock feed line;   (c) providing a raw water network connection between a hydrostatic lock outlet line and said raw water network;   (d) providing a fresh water flush valve connected between said hydrostatic lock feed line and said hydrostatic lock outlet line, said fresh water flush valve being normally closed;   (e) providing a swing gate valve between said raw water network connection and said raw water inlet, said swing gate valve being configured to close when a pressure within said raw water network exceeds a pressure in said raw water inlet;   (f) while said engine is running and said raw water pump is operating, energizing said pump to create a pressure in said hydrostatic lock feed line that exceeds said pressure in said raw water inlet;   (g) opening said fresh water flush valve, thereby allowing fresh water to flow into said raw water network; and   (h) holding said fresh water flush valve open and continuing to energize said pump for as long as a salinity measured by said salinity sensor remains above a defined threshold.   
     
     
         12 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 11 , comprising:
 (a) maintaining said engine in a running state; and   (b) when said salinity measured by said salinity sensor falls below said defined threshold, shutting off said engine   
     
     
         13 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 11 , comprising:
 (a) providing a system controller including a processor running software retrieved from a memory;   (b) said system controller controlling said fresh water flush valve and said pump;   (c) said system controller monitoring said salinity sensor; and   (d) said system controller executing said steps of closing said fresh water flush valve and shutting off said pump when said salinity measured by said salinity sensor falls below said defined threshold,   
     
     
         14 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 12 , comprising:
 (a) providing a system controller including a processor running software retrieved from a memory;   (b) said system controller controlling said fresh water flush valve, said pump, and a run state of said engine;   (c) said system controller monitoring said salinity sensor; and   (d) said system controller executing said steps of closing said fresh water flush valve, shutting off said pump, and shutting down said engine when said salinity measured by said salinity sensor falls below said defined threshold.   
     
     
         15 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 11 , wherein said salinity sensor is located proximate said raw water outlet. 
     
     
         16 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 11 , wherein said salinity sensor is located proximate a point where said raw water is fed into an exhaust stream from said engine. 
     
     
         17 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 11 , wherein said pump is a native fresh water pump within said vessel. 
     
     
         18 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 14 , comprising:
 (a) said system controller detecting when a user is shutting down said engine; and   (b) said system controller thereafter maintaining said engine in said run state while said system controller energizes said pump and opens said freshwater flush valve.   
     
     
         19 . The method for reducing the salinity of water contained within said raw water network as recited in  claim 18 , comprising said system controller maintaining said engine in said run state until said salinity measured by said salinity sensor falls below said defined threshold, and thereafter shutting down said engine. 
     
     
         20 . The method for reducing the salinity of water contained within said raw water network as recited in claim  20 , wherein said system controller continues to energize said pump and hold open said fresh water flush valve for an interval of time after shutting down said engine.