As steam experts, one thing has long been clear to us at JUMAG: steam is a core element of modern industry. And as everyone knows, steam consists of water. What many don’t realize, however, is that the higher the remaining water content in the steam, the lower the steam quality and the higher the resource consumption and operating costs. The solution is industrial steam dryers, which minimize the water content in the steam and thus produce dry steam that guarantees efficient and sustainable production.
Below, you’ll learn everything you need to know about how industrial steam dryers work and the common models.
Why steam dryers?
As mentioned, the less water in the steam, the higher the quality. But why? The simple answer is: Along with the water, salts enter the system, which contaminate the steam and lead to increased material wear. The cause of this is what is known as water entrainment. As the name suggests, water from the pressure vessel is entrained along with the steam. This water is called primary condensate.
But why is water entrained at all? Two reasons should be mentioned here:
- Due to the constant evaporation of the water in the pressure vessel, the salts thicken. This increases the pH value and the chance of foaming. And because the salts are located on this enlarged surface, they are easily entrained when the steam is drawn off and thus enter the system.
- When the steam decreases sharply, the pressure in the pressure vessel drops so drastically that the water is swept upwards along with the steam like a tornado.
Any water entrainment simultaneously means energy and water loss, which should be avoided at all costs.
Steam dryers (continuous desalinators) are often used to protect the system from water entrainment. They divert the initial condensate to a blowdown tank or reclaim it for reuse.
The Consequences of Water Entrainment
The consequences of initial condensate in the steam line lead to a high salt concentration, which can clog strainers, for example. This prevents downstream components from functioning properly, and the entire system malfunctions.
Another problem is water hammer, which means that the steam pushes the initial condensate forward, causing it to strike pipe bends and valves. Further material damage is caused by abrasion: The condensate, which is “driven” through the pipes by the steam, has an abrasive effect on the material. This thins the pipe wall, making it more susceptible to material damage.
In addition, the condensate acts as an insulator on the pipes. This often impairs the heat exchange effect. This, in turn, negatively impacts efficiency.
How does water entrainment occur?
The causes of so much water being entrained can vary and must be examined individually. Conventional steam dryers often only address the symptoms instead of the causes, resulting in significant energy loss.
The baffle plate steam dryer
Now a device comes into play that would not only be a hit with any hangman, but can also dry efficiently. 😉 The principle of the baffle plate steam dryer is simple: The steam to be dried first hits a baffle plate. This separates the water through a suitable condensate drain. As the steam tends to rise, it strips off the remaining moisture on the internal fins. This separates more water. Now, thoroughly dried, the steam creeps over the baffle plate and escapes through a flange attached to the rear.
Thanks to its compact design, the baffle plate steam dryer requires little space, which is a significant advantage for many companies. However, this system is not entirely without its problems: The separation rate depends on the throughput rate and can be significantly reduced by this. In addition, the steam velocity must be precisely adjusted. If the steam is too fast, it “jumps” over the baffle plate with the water. If it is too slow, it “creeps” over it with the water. In both cases, the separation rate is further negatively impacted. The compact design of the impact plate steam dryer also results in a short distance between the trap and the steam inlet. This has the disadvantage that excessive water surges cannot be removed in time. This can cause the initial condensate to enter the system via the incoming steam.
As you can see, despite its economical design, this system is not equally suitable for every application.
The cyclone steam dryer
“Cyclone” means “rotating” and is a term for whirlwinds. It’s not without reason that the cyclone steam dryer is named after this technical term. It uses centrifugal force to “expel” the steam. When the steam enters the system, it is guided in such a way that it spins. This process dries it similarly to a spin cycle in a washing machine.
A major advantage of this system is its compactness and, in principle, a good separation rate. Why only in principle? The same applies to this system: the components must be precisely matched to the flow rate to maintain a good separation rate. Furthermore, there remains a risk that the steam will get too close to the trap, and the initial condensate will be carried into the pipes if a large amount of water is entrained. A potential pressure drop should also be considered in the calculation.
In summary, the separation rate depends on many factors and can be negatively influenced depending on the individual circumstances.
The impact plate cyclone steam dryer
As the name suggests, the impact plate cyclone steam dryer is a combination of both systems: Similar to the impact plate steam dryer, the steam first impacts the internal steam outlet pipe. During this process, the steam loses an initial portion of its moisture. It is then guided through guide rails into the centrifuge to remove the residual moisture. The dry steam rises through the pipe and enters the system through the counter flange. Another aspect is the design, which reliably maintains a good separation rate even with larger water surges thanks to a greater distance between the steam inlet and the trap.
The combination of both systems achieves what is rarely achieved individually: Tests show a very good separation rate while simultaneously maintaining steam pressure. The impact plate cyclone steam dryer thus combines the positive aspects of its predecessor systems into a unique and highly efficient industrial steam dryer. Our clear favorite!
