What is Pure Steam?

Pure Steam, also known as Clean Steam, is evaporator purified water that is utilized throughout the clean manufacturing process. Common uses include equipment sanitization, component sterilization and clean room humidification. Typically, Pure Steam is generated by pumping a purified feedwater through a shell and tube evaporator, which when heated by plant steam, evaporates and migrates to a centrifugal separator. The centrifugal separator, which contains a controlled level of condensed, concentrated water, functions to force all remaining moisture from the steam, produced a dry, high purified stream of Pure Steam. Click below to learn more about Aqua-Chem’s standard line of Pure Steam Generators (PSG’s).

Our Pure Steam Generators design incorporates a vertical shell and tube evaporator coupled at the top and bottom to a reservoir of feed water.  Utility steam is applied to the outer surface of the evaporator tubes with the inner surface of the tube in contact with feed water.  As the feed water is heated, boiling occurs producing a vapor/liquid mixture with steam occupying the center of the tube and forming a liquid layer at the tube surface.  The difference in density between the liquid/vapor mixture in the tube and the liquid in the reservoir induces a flow of feed water from the reservoir to the bottom of the evaporator thus supplying additional feed water to the evaporator.

This process of evaporation and feed water replenishment to the evaporator occurs continually and results in a circulating action with steam and liquid entrainment being discharged from the top of the evaporator tubes and additional feed water supplied from the reservoir.  An entrainment separation mechanism returns the entrainment to the liquid reservoir for reuse and allows the steam to be discharged as product. 

The rising film evaporator is also referred to as natural circulation evaporator.  This evaporation method ensures constant wetting of tube surfaces thus minimizing the potential for scale formation and corrosion of the tube surface.  The only mechanism necessary to induce the rising film action and circulation through the evaporator tubes is the application of utility steam to the evaporator.


How It Works

The compact Aqua-Chem Pure Steam Generator produces pure steam, meeting the stringent water quality requirements for Water-for-Injection per USP XXIII. Our three step design of baffles, fine mesh pad, and tangential stream entry into the separator section causes the steam to spin and change direction to eliminate contaminated water droplets from being carried over with the pure steam. The compact unit is the result of a very efficient design that uses a rising film evaporation and thermal syphon technology. This allows the unit to instantaneously evaporate feed water into pure steam. Our PLC control has been designed to meet the quick demands of pure steam loads by automatically reacting to the plant steam load and feed water demands. This process ensures that the proper amount and pressure of pure steam is produced for your needs.


Standard Features

  • PID level controllers for optimal feed water level control in the evaporator columns.
  • Condenser is double tube sheet and tube heat exchangers to condense and cool the pure steam as WFI.
  • Feedwater preheaters are double tube sheet, shell and tube heat exchangers for long term reliability.
  • New evaporator gasket design for optimal seal.
  • Extended 5 year warranty on the titanium U-tube bundle. The U-tube design addresses the issue of thermal cycling by allowing the tubes to expand and contract freely.
  • Shell-Side Evaporation Design
    • Ensures heat transfer surface will shed potential scale formation
    • Submerged-tube rising-film design eliminates dry tube “hot spots”


Optional Features

  • Electropolish Feedwater and Pure Steam Surfaces to 15 Ra
  • Feedwater Conductivity System
  • Pure Steam Condensate Sampling system
  • Pure Steam Conductivity System
  • Pure Steam Condenser for WFT Production
  • Carbon Steel Frame
  • Aluminum Lagging

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