How does a steam ejector compress gases at low pressure?

A steam ejector functions by utilizing the momentum of high-velocity steam to compress gases from a low-pressure environment. The process occurs as follows:

• Entrainment: High-velocity steam enters the main body of the pump, creating a suction effect that draws in the gas from the inlet line.
• Momentum Transfer: The steam transfers a portion of its momentum to the gas, effectively entraining it into the flow.
• Compression: The resulting mixture of steam and gas enters a venturi tube known as a diffuser. Within this component, the kinetic energy of the mixture is converted into pressure energy.

Through this conversion, the energy originally contained in the steam is used to compress the gas, raising it from a low pressure to a higher pressure level. These devices are frequently employed as vacuum pumps in industrial settings to handle large volumes of vapors and gases at low pressures.1