Method and apparatus for effecting high recovery desalination with pressure driven membranes

A tapered flow desalination system comprising:

• a system inlet feed line coupled to a first high pressure booster pump configured to provide a high pressure feed stream to the system, wherein said first high pressure booster pump comprises an inlet and an outlet;
• blocks of membrane pressure vessels arrayed in parallel, wherein the outlet of said first high pressure booster pump is coupled by means of flow lines to said blocks at first opening sides of said blocks;
• a second high pressure booster pump, comprising an inlet and an outlet, coupled at said second high pressure booster pump inlet by a first bypass line parallel to said blocks, to said first high pressure booster pump outlet, wherein said second high pressure booster pump outlet and inlet are also coupled by means of flow lines to said blocks at second opening sides of said blocks and wherein said first bypass line is also coupled by means of flow lines to said blocks at said second opening sides of said blocks;
• a system outlet flow line coupled to said first opening sides of said blocks by means of flow lines and coupled to said second opening sides of said blocks and to the second high pressure booster pump outlet, wherein said system outlet flow line is coupled to said second opening sides of said blocks and to said second high pressure booster pump outlet by means of a second bypass line;
• wherein the first bypass line comprises a valve and wherein the second bypass line comprises a valve;
• wherein at least two of the flow lines coupling between said first high pressure booster pump outlet and said first opening sides of said blocks each comprise a valve;
• wherein at least two of the flow lines coupling between said second high pressure booster pump outlet and said second opening sides of said blocks each comprise a valve;
• wherein at least two of the flow lines coupling between said second opening sides of said blocks and said second high pressure booster pump inlet each comprise a valve;
• wherein at least two of the flow lines coupling between said first opening sides of said blocks and said system outlet flow line each comprise a valve;
• and
• wherein said first bypass line is configured to bypass excess flow from said first high pressure booster pump outlet to the second high pressure booster pump inlet without changing said excess flow composition within said first bypass line.