Desuperheaters

JET-VAC® Venturi Desuperheaters reduce the temperature of vapors flowing in a pipeline by heat transfer through evaporation. Liquid injected at the throat of the venturi is atomized into small droplets by the high vapor velocity. Superheated vapor is cooled by evaporation of the droplets as they flow downstream.

JET-VAC®Desuperheaters are used in chemical plants and refineries.

Benefits

  • Protect critical equipment in process plants against heat distortion
  • End product deterioration by superheated vapors
  • Eliminate need for heavy insulation of steam lines
  • Reduce expensive, heat-resistant alloys in process equipment
  • Lower superheated steam temperature for use in operating auxiliary equipment



Desuperheating Steam

To be used as steam desuperheating liquid, steam condensate must contain no dissolved solids that could deposit on the pipe walls. The condensate enters slightly downstream of the venturi throat where it is sprayed into the vapor flow at a minimum pressure of 5 to 10 psi above steam line pressure. This achieves a relative velocity between condensate and steam that produces the smallest droplet size. Superheated steam temperature may be reduced to a practical 5° to 10°F above saturation. Velocity of flow and required heat reduction determine how far downstream this occurs. In many cases, the distance is less than 20 feet.

Desuperheating hydrocarbons

The relatively small latent heat of hydrocarbons requires much more liquid in the desuperheating process than high-temperature steam. JET-VAC® Venturi Desuperheaters introduce the required amount of liquid through a series of nozzles paralleling the vapor flow. Counter flow is not necessary to break hydrocarbons into small droplets as their surface tension is less than water.

Design and fabrication standards

JET-VAC® Venturi Desuperheaters are designed and fabricated in accordance to the ASME Boiler and Pressure Vessel Code section VIII Division 1 and other international codes. Carbon steel is normally used up to approximately 750°F, low alloy steels up to 1000°F and high alloy steels at greater temperatures.

Contact an JET-VAC® Application Engineer