Paul Mueller Company Academy

How a Clean Steam Generator Works

A sterile and clean environment is required for many commercial applications and industries including healthcare, pharmaceuticals, animal health, biotechnology and cosmetics. When manufacturing the specialized equipment for these industries, clean steam generation systems must be in place to ensure sterilization for equipment such as autoclaves, washer-disinfectors, and pharmaceutical manufacturing equipment. Some breweries that want a completely pure final product also use clean steam generators to sterilize their kegs.


Having the proper sterilization equipment for these commercial applications makes all the difference in achieving the highest possible quality standards. Properly-designed clean steam generators produce large amounts of pyrogen-free and endotoxin-free steam to keep production processes sterile and running smoothly. Clean steam is different from the steam generated in cooking or in clothing care. True clean steam, when condensed, is suitable for water-for-injection in pharmaceuticals. 


Clean Steam Generation


Clean steam is free of any additives, impurities, and other substances that could compromise the sterility of a finished product. Clean steam for commercial applications is created by specialized equipment that heats purified water. A manufacturer of clean steam generators typically makes the equipment out of stainless steel to produce a high-quality system that will not corrode.

Contrast this with a standard steam generator, also referred to as a boiler, that utilizes a standard water line. Note that you can’t take a general utility steam generator and simply convert it to clean steam. You must have a specific steam generator using purified water to produce clean steam.


How a Clean Steam Generator Works

A clean steam generator converts incoming purified water into clean steam using utility steam on the other side of the generator as the heating medium. The utility steam and the clean steam never mix. The resulting clean steam relies on the quality of water being fed into the system. However, contaminants that do happen to get into the system can be removed by various methods.

The feedwater is pumped into the industrial clean steam generator system at higher pressure than the required clean steam pressure in order to provide the temperature differential for heat transfer. It’s important that any surfaces that come into contact with the water be made of stainless steel to maintain steam quality.

The water source for clean steam generation must be virtually free of impurities. Clean steam generation must meet very strict requirements for critical applications in industries that rely on sterile environments and equipment. It’s easy to assume that steam from boiled water is clean and pure, but the standards for “clean” water for certain uses —especially pharmaceutical applications— are exceptionally high.  

To maintain the purity of the steam generated, small traces of contamination must be captured. For that purpose, there are water treatment systems that use fine, semi-permeable membranes to physically remove contaminants in the system. 

This pre-treatment removes contaminants in the feedwater and helps ensure clean steam is absolutely pure. Conventional water vapor is sometimes referred to as "dirty steam" because it contains high levels of carbon dioxide and other contaminants like sulphur dioxide. Water quality can also be ensured by controlling the amount of carbon dioxide, carbon monoxide, and activated carbon in the water, as well as other factors. 

For less maintenance, high quality clean steam generators are designed to produce a centrifugal force in the separator which propels entrained droplets to the wall of the separator thus producing an effective separation of impurities. No internal components such as vanes, demisters, or baffles are needed to provide the necessary 3 log separation ratio.


Clean steam generator process flow diagram


Clean Steam Generator Design and Requirements


Because clean steam must be devoid of impurities and various chemical substances, clean steam generators are designed with specific features and elements that ensure the cleanest steam is generated. To achieve these high standards of sanitization, clean steam generators for the pharmaceutical industry must be:


  • Built using corrosion-free material such as high-quality stainless steel
  • Crafted using high-quality welding, free of cracks and grooves
  • Fully sealed and leakage-free
  • Designed to minimize stagnant water and the growth of microorganisms
  • Built in compliance with Current Good Manufacturing Practices (cGMP) defined by regulatory bodies like FDA, ASME, and JIS


Topics: Pharmaceutical

About Paul Mueller Company Academy

Teaching and sharing ideas has long been part of the rich heritage at Paul Mueller Company. We have almost a century of quality craftsmanship guiding the way we apply new learnings. Paul Mueller Company Academy is a collection point for those learnings, so we can collaborate and grow more successful together. You will find articles, blogs, guides, infographics and more dedicated to furthering knowledge for all, in the world of stainless steel processing equipment solutions. We hope you enjoy!