Partial load enabled falling film evaporator and method for operating a partial load

A partial load enabled falling film evaporator comprising:

• an external outer shell;
• a number of tubes the internal side of which has a liquid film flowing downwards, the tubes comprising an internal chamber;
• upper end devices for distributing the liquid to the individual tubes;
• lower end devices for collecting residual liquid and vapor;
• a vapor extracting device for withdrawing the vapor forming inside the tubes;
• a device for withdrawing the non-evaporated portion of the liquid inside the tubes;
• devices linked to the internal chamber of the tubes;
• partitions that separate the internal chamber of the tubes and the devices 9, 10, 11, 12, 13 and 17, linked to said chamber, for distributing and collecting fluids from the space enclosing the tubes;
• a device for feeding a mixture of the gases and vapors to a chamber enclosing the external side of the tubes;
• a device for withdrawing condensed liquid from the chamber enclosing the external side of the tubes;
• a header for distributing liquid to be evaporated;
• and
• a device for discharging the vapors and the gases from the chamber enclosing the external side of the tubes, wherein
• the header distributes the liquid to be evaporated among the individual internal sides of the tubes and is partitioned in at least two segments, and
• means for feeding or omitting each of these segments with liquid.