Steam is used extensively on most sites for:
• indirect heating in steam heaters
• steam tracing for pipes and storage tanks (i.e. steam pipes around the exterior) to keep the materials inside from solidifying
• direct heating of water through live steam injection;
• creation of vacuum in steam ejectors
• mass and heat exchange by live steam injection in distillation;
• reduction of partial pressure in gas-phase reactors;
• combustion processes to atomize fuel oil
• injection into combustion processes to lower NOx emissions through reduction in the flame temperature
• injection into flares to assist the combustion
• power generation in steam turbines.
It is no accident that steam is used extensively for process heating as it provides a number of useful features that include:
• energy can be generated at one point and distributed;
• it is a convenient form of transferring energy around;
• it has a wide range of operating temperatures;
• it has a high heat content through the latent heat;
• the temperature is easy to control through control of the pressure;
• it can be used to generate power in steam turbines and generate vacuum in steam ejectors;
• it does not require expensive materials of construction;
• it is nontoxic and losses are easily replaced.
The major components of the steam system are:
• boiler feedwater treatment
• steam boilers
• steam turbines
• gas turbines
• steam distribution
• steam users
• condensate collection and recovery.
Consider now each of these components in turn.