Water bath evaporator for liquefied gases

TLDR: In this article, a water bath evaporator for liquefied gases has a propeller incorporated in a heat exchanger or via an external pump which circulates the water, and the operation is controlled by the propeller whose speed, direction of rotation and blade pitch are variable to match the characteristics and flow requirements of the gas.

Abstract: Water bath evaporator for liquefied gases has a propeller incorporated in a heat exchanger or via an external pump which circulates the water. Liquefied gas, such as nitrogen, oxygen or argon, requires to be evaporated and raised to a temperature of about 15 deg C for use as a welding gas. Liquefied gas enters the heat exchanger at (7) to a manifold at the base of the vessel. Here it enters coils (2) in which most of the heat exchange takes place so that gas is collected in an upper manifold leading to exit (8). The vessel is filled with water, at a temperature of 80 deg C or more, which is agitated by propeller (9) inside the central coil core (11). Heat is supplied to the water, in the form of steam or electrical energy, through line (3). Alternatively the water is circulated through an external pump. Any surplus, cool, water is removed (line not shown). The operation is controlled by the propeller whose speed, direction of rotation and blade pitch are variable to match the characteristics and flow requirements of the gas, to achieve a given exit temperature. Where an external pump is used there is provision for variable speed control, or means for varying the flow at constant speed, and reversal of the circulation flow.