River water heat exchanger for cooling process liquid in a paper-making machine

A method of cooling a process liquid in a paper-making machine using a source of cooling water, said method comprising the steps of:

• providing a first tank having a plurality of first walls, said first tank having a first inlet connected to at least one of said first walls and the source and a first outlet connected to at least one of said first walls and the source;
• providing a second tank having a plurality of second walls, said second tank having a second inlet connected with the paper-making machine and a second outlet connected with the paper-making machine;
• providing an intermediate chamber defined by and disposed between at least one of said first walls and at least one of said second walls, said intermediate chamber having a heat transfer liquid therein;
• transporting the cooling water from the source to said first inlet and into said first tank;
• transporting the process liquid from the paper-making machine to said second inlet and into said second tank;
• providing a pressure differential between the intermediate chamber and each of the first tank and the second tank, thereby causing at least one of the cooling water and the process liquid to flow into the intermediate chamber in the event of a leak in at least one of the first walls and the second walls;
• and
• transferring heat through said heat transfer liquid in said intermediate chamber from the process liquid to the cooling water.