Vertical heat exchanger

A vertical tube and shell heat exchanger comprising:

• a pair of first fluid passing ports for flow of a first fluid through at least one vertical tube;
• an upper tube sheet through which the at least one vertical tube passes;
• a pair of second fluid passing ports for flow of a second fluid through the vertical shell;
• and
• a vent pipe having two ends, for venting a gas, the gas locating to the upper portion of the vertical shell during operation of the vertical tube and shell heat exchanger, at least part of one end of the vent pipe being made of the upper tube sheet and being fixed to the boundary between the upper tube sheet and the vertical shell and the other end of the vent pipe being fluidly connected outside the tube and shell heat exchanger to a second fluid passing port passing the same fluid as the vent pipe, whereby the fluid flowing through the vent pipe drives out the gas, wherein the fluid connection of the vent pipe with the second fluid passing port is further in fluid communication with a pipeline downstream of the fluid connection, the pipeline having at least a portion at a level higher than the upper tube sheet and which comprises a valve located at the high portion thereof, configured to expel the gas.