Water is treated and used by the pharmaceutical industry in a myriad of ways. Pure steam generators are among many paraphernalia that helps to produce water, or in this case, steam that meets the stringent standards of pharmacopeias around the world. They are specifically designed to facilitate the production of pure steam, which has several use cases in the industry.
What is Pure Steam?
In order to understand pure steam generators, one must first understand what pure steam is. Pure steam, also known as clean steam, is defined as saturated steam produced from additive-free water and is free from non-condensable gases. It is derived by distilling purified water and has a prescribed endotoxin level of less than 0.25Eu/ml. Basically, pure steam, upon condensation, should be able to meet the standards of Water for Injection (WFI) in terms of conductivity, TOC, and levels of endotoxins.
Pure steam is used for sterilization or sanitization processes in tanks, reactors, supply, and distribution pipe systems. Pure steam acts as the ideal heat transfer media. Apart from being of vital importance in the pharmaceutical manufacturing industry, SIP water systems have found applications in the biotechnology, cosmetics, and food processing industries.
Specifics of a Pure Steam Generator
Pure steam generator systems use a once-through, forced flow, design to convert the incoming feed water to steam. During the single pass through the water coil, the heat from the hot gases is transferred to the water to convert it to steam. The power feed to produce high quality can be either industrial steam or electricity.
Pure steam generator systems should be designed and built-in in compliance with the Current Good Manufacturing Practices (cGMP) defined by various national and international regulatory bodies like FDA, ASME, and JIS. The steam also needs to pass steam quality tests like non-condensable gases, degrees of superheating, and saturation tests as per the requirements.
The most common method employed to treat source water is the reverse osmosis (RO) water treatment system, which uses a fine, semi-permeable membrane to physically remove impurities. This pre-treatment reduces impurities in feed water.
Water quality can further be controlled by applying additional treatments like active carbon treatment, UV treatment, and thorough removal of chemicals and microorganisms.
The steam also needs to pass steam quality tests like non-condensable gases, degrees of superheating, and saturation tests as per the requirements.
Points to Keep in Mind for Fail-Proof Pure Steam Generation
While pure steam generators in the pharmaceutical industry are commonplace, there are some challenges that they come with. Here are a few things to keep in mind to ensure a proper pure steam generation process.
Materials Used
Pure steam, when pressurized, can easily corrode the piping network system if they are not made of the highest quality stainless steel. In fact, the steam in itself can get contaminated if proper resistant materials are not used and properly maintained. However, it is obvious that quality comes at a cost. Thus cutting corners is simply not an option here.
Controlling Contaminants at the Point of Entry
Pure steam generators must also ensure zero contaminants at the point of entry. Chemical and microbial contaminants may enter the system in many, and the pure steam generation system must take that into account and avoid possible issues like leakages or air being pulled into the system.
Preventing Condensate Collection
Care must also be taken to ensure that the condensate is not allowed to gather in the system, as upon cooling, the stagnant water can become a breeding ground for bacteria. While these bacteria can be ideally killed by the produced pure steam, their breakdown product, including endotoxins, may be left behind as the temperature of pure steam is not enough to get rid of endotoxins. This can majorly compromise the integrity of the steam and everything that comes in contact with it.
Removing Air from the System
Air in steam can lead to reducing the optimal temperature of the steam resulting in sterilization failure; thus, it should be avoided at all costs. Usually, steam traps are used to ensure air does not interfere with the system. An air vent or an air eliminator installed at a high point in the distribution can also help to achieve the same goals.
Controlling Superheating
When steam is under pressure, as when a low-pressure header is fed through a pressure reducer or when there is a significant pressure drop through piping, it can result in superheating.
Also, heat losses from piping cause the steam temperature to fall, again allowing the steam to move back toward saturation.
So as a general rule, pressure should not drop below 50% of the absolute supply pressure seems to avoid adverse superheat.
How to Select the Best Pure Steam Generator
Zeroing in on a specific pure steam generator relies on a bunch of different factors. The initial considerations are, of course, practical. Budget, scope, and specific needs are, of course, the first things to be taken into account. Some of the technical aspects that can be considered include the following:
- Lesser number of moving parts which minimizes maintenance downtime
- Wide turndown possibilities
- Simple designs with minimal internal components that require less inspection and maintenance
- High flexibility with a variable production capacity with minimal plant modification
- Energy efficiency
In addition to these, having validation support is also an important factor that can help you choose the right pure steam generator.
Generating pure steam in a SIP water system involves a thorough understanding of the pure water systems and the current best market practices. TSA Water Systems is a market leader in designing and manufacturing high-purity water systems. Our technical expertise, coupled with a problem-solving approach, helps us in designing and installing efficient pure steam generators that meet and exceed all national and international standards. Our pure steam generators are available in various models with flow rates ranging from 50 to 1500 kgs per hour and are compliant with USFDA 21 CFR part 11 and GAMP 5.
