Low temperature techniques

The growing need for individual hydrocarbons, particularly ethane, propane, and the growing consumption of liquefied gases has led to an increase in the fraction of low temperature processes in the gas processing activities.

Today, the following systems are used in the low temperature processes:

• With an external cooling cycle, using special circulating cooling media – either individual components (propane, ethane, ethylene, ammonia) or multicomponent mixtures (e.g. a mixture of light hydrocarbons); for deep cooling, cascade cooling cycles are used which are based on several successive cooling cycles with various cooling agents featuring different boiling temperatures.
• With an internal cooling cycle, using direct cooling of the process streams involving isoenthalpic expansion by means of chokes or isoentropic expansion by means of expanders.

• With a combined cooling cycle, e.g. using externally circulating cooling medium at the initial stage with subsequent cooling of the stream by means of a choke or an expander.