Let’s recap quick: wet steam is the steam you usually see around your house and basically everywhere not investing seven to eight figure checks in their steam system. This wet-steam carries water vapor, which is the actual white, puffy cloud you see. Dry steam is essentially invisible, hot as fire, and essential in industrial scale productions. That begs the question though, is there an industry for wet steam too? Surely the dry-stuff is better?
Moisturizing the Product
It turns out, there are a ton of applications where it’s essential to add moisture to a product without actually soaking it. Consider, if you use dry steam, you’re not going to make the product wet, but you will dry it out. Between the heat and zero-humidity air, anything that can evaporate from the product will do so.
Dry products presents a wide range of problems. Dry things are often inflexible and brittle. Consider if you leave a shirt in your clothes drier for hours upon hours (do not do this, you’ll probably start a fire), if it survives, it’ll be rough, stiff, and uncomfortable. Dry steam works well enough for a quick cleaning of clothes, but it’s not good for prolonged exposure.
This same thing is true in other types of production, consider something like a paper pill or a printing press. If the paper becomes too dry, it might tear inside the machinery. Excessively dry paper is prone to cracking, tearing, and crumbling. In these instances, wet steam is used, in moderation, to prevent the paper from becoming too dry. This is somewhat ironic, as wet paper is how we got the dehumidifier and first air conditioner. Paper with inconsistent moisture levels changes dimensions and breaks printing presses.
In other products, the steam is an essential ingredient. “Dry” pet food it turns out, has a surprising amount of moisture in it. Even kibble can have 10-30% water content. Wet, canned food typically has 70% or more water in it. For the dry food, the moisture can get there a few ways, it depends on the production. In some cases, it’s from a high-moisture production process, then drying. In other cases, the food is created in an incredibly dry process, then conditioned with hot, wet steam to soften it and even help to sterilize it.
All this steam has a complex set up that makes it safe, clean, and reliable in production. The exact configuration will vary from installation to installation. In many applications, there are multiple boilers involved to ensure everything remains sterile.
Consider that the heating system of a facility will hold stagnant water when the system sits idle. During the summer, the heating system may not have any water flowing through it at all. This creates a breeding ground for bacteria and contaminants, corrosion, and other problems. These are things we don’t want to blast into cooking processes or into high quality products. Your customers appreciate that their newspaper doesn’t have gross, blue-green molds growing on them.
The solution is for facilities to have isolated steam systems. This eats a bit into the economies of scale. If you already have steam heat, you will unfortunately need a separate boiler to support near every other steam service. Your dedicated steam system typically uses a sterilized water supply. In some cases, this is water that’s been thoroughly filtered and purified, in other cases it has additives to prevent corrosion in industrial equipment.
These issues are less prevalent in dry steam, which is thoroughly heated and processed. In some cases, a dry-steam facility may be able to get away with a single main boiler for the start of their steam system. Dry steam doesn’t carry contaminants or additives and it’s hot enough that bacteria and viruses stand no chance of survival.
Admittedly, steam is much more complex in implementation than it is on principal. Like many things, it does a unique set of jobs and very few things can compete with it. Installing it has its own costs and challenges, but that is just a testament to how incredible steam is. If your process benefits so much from steam that you install a second steam or heat-generating system in a building, it must do a lot to offset those costs. Steam is one of those things that returns heavily on its investment.
We Really Need Steam?
Yep! It’s even used in the food you eat every day. Steam heating can be used to help sterilize canned foods. Some products are cooked with steam to begin with. There is a whole industry around culinary steam. To say nothing of its other uses, for drying, production, heating, and so on. It takes a little more energy than just heating water, but it has near countless uses.