Steam Separator – An Effective Solution for Dry Steam

Are you sure the steam in your system is dry enough?

In most industrial plants, a steam separator is not an “auxiliary” device but a critical link that determines energy efficiency, equipment lifespan, and operating costs. Even a slight increase in steam moisture can significantly raise energy losses and the risk of water hammer.

 I. How does a Steam Separator work?

A steam separator is installed directly on the steam pipeline, typically upstream of pressure-reducing valves, control valves, or right before steam-consuming equipment. Its core function is to remove moisture directly from the moving steam flow, rather than waiting for condensate to accumulate like passive solutions.

When wet steam enters the separator, the internal structure forces the flow to change direction and creates a centrifugal swirling motion. Due to differences in density and inertia, condensate droplets—much heavier than steam—are thrown out of the main steam flow and strike the separator wall. There, the water loses kinetic energy, flows down to the bottom of the separator, and is discharged through a steam trap.

The separated steam exits the separator with a higher dryness fraction, meaning the useful energy content in each kilogram of steam increases significantly. This is critical because condensate has much lower enthalpy; when mixed with steam, it reduces heat-transfer efficiency and forces downstream equipment to “burn more fuel for the same output.”

Beyond moisture removal, the swirling motion also helps retain solid contaminants present in the system, such as welding slag, metal particles, and debris generated during installation and operation. If not removed early, these contaminants can erode valve surfaces, jam control mechanisms, and shorten the lifespan of downstream equipment.

A key difference between a steam separator and a steam trap lies in how water is handled. Steam traps only discharge water after it has condensed and accumulated at low points in the piping. In contrast, a steam separator proactively removes water while it is still suspended in the steam flow, before it can cause hazards such as water hammer, pipe vibration, or valve damage.

In other words, if a steam trap is a “corrective” solution, a steam separator is a preventive solution at the source, helping the steam system operate more stably, safely, and efficiently.

II. Why is steam in industrial systems always wet?

In real operating conditions, steam is never completely dry, especially when:

In systems with steam pipelines longer than 50 meters, steam quality often degrades significantly due to heat loss to the environment. When steam passes through pressure-reducing valves, pressure regulators, or modulating control valves, continuous changes in pressure and velocity cause part of the steam to condense into water. Additionally, frequent changes in flow direction, pressure drops, and expansion during operation further increase the amount of condensate mixed into the steam flow, making the steam wetter and reducing overall system energy efficiency. Each pressure drop or change in direction causes part of the steam to condense, lowering steam quality.

III. Negative impacts of wet steam in a steam system

Steam carrying condensate leads to a range of serious problems:

• Water hammer → vibration and pipe cracking
• Valve erosion, sticking, and leakage
• Reduced heat-transfer efficiency
• Increased fuel consumption
• Damage to steam-consuming equipment
• Higher maintenance costs and downtime

All of these issues originate from poor steam quality.

IV. Comparison: Steam Separator vs. Steam Trap

V. Operating principle of a Steam Separator

Centrifugal swirling principle

A steam separator operates based on centrifugal force:

• Steam enters the separator
• Guide vanes create a swirling motion
• Heavier water droplets are thrown to the vessel wall
• Water falls to the bottom and is discharged
• Dry steam continues downstream

The better the design, the higher the water separation efficiency.

VI. Second critical role: solid contaminant removal

Besides condensate, steam pipelines often contain:

• Welding slag
• Sand and dust
• Paint flakes and metal particles

These contaminants cannot be retained by ordinary steam traps alone.

A steam separator effectively captures contaminants, helping to:

• Protect pressure-reducing valves
• Reduce steam trap blockage
• Extend equipment lifespan

VII. Steam separator design – Why not all designs are effective

The efficiency of a steam separator depends heavily on its internal design:

• Shape of guide vanes
• Swirl angle
• Steam velocity
• Separation chamber size

Helical centrifugal vane design

DIVI Group steam separators use:

• Helical guide vanes
• Strong swirl without excessive pressure drop
• Very high water separation efficiency

VIII. Manufacturing process and technical standards

All steam separators are manufactured according to pressure vessel standards:

• TIG welding under inert gas for all welds
• Non-destructive weld inspection
• Pressure testing at 1.5 times design pressure
• Actual water separation performance testing

???? Only equipment meeting all standards is released from the factory.

IX. Experimental verification of separation efficiency

Simulation of real operating conditions

• Boiler: 1 ton/hour
• Fuel: pellets
• Steam artificially humidified through a heat exchanger
• Steam flow split into two branches

Observed results

• Branch without separator: significant water carryover
• Branch with separator: almost no water
• Large amount of water discharged at the separator bottom

This proves that water is removed directly from the steam flow.

X. How much more energy does dry steam deliver?

From a thermodynamic perspective, assume the steam system operates at 3 bar. The impact of a steam separator on steam quality and energy becomes very clear.

Without a separator, steam dryness is only X = 0.9, meaning that in 100 kg of total steam flow, only 90 kg is dry steam while 10 kg is entrained condensate. Because condensate has much lower enthalpy than saturated steam, the total energy carried by this 100 kg of steam is only about 268,864 kJ.

With a steam separator installed, water is removed directly from the steam flow, increasing dryness to X = 0.98—equivalent to 98 kg of dry steam and only 2 kg of water per 100 kg of steam. In this case, the total useful energy increases to 287,772 kJ.

Thus, by increasing steam dryness by just 0.08, the energy content rises by 18,908 kJ—approximately 7%, a very significant figure when considering large steam flow rates and continuous industrial operation.

XI. When should / shouldn’t a Steam Separator be installed?

Strongly recommended when:

• Steam pipeline length > 50 m
• Pressure-reducing valves or control valves are present
• Industries such as textiles, laundry, and food processing
• Large amounts of condensate are observed

May not be necessary when:

• Short pipelines
• Steam used directly and moisture does not affect the product

XII. FAQ

1. How does a Steam Separator work?
A steam separator operates on the centrifugal swirling principle, forcing the steam flow to change direction and separating condensate while it is still suspended in the steam. Heavier water droplets are thrown to the vessel wall, flow to the bottom, and are discharged, while dry steam continues to the consuming equipment.

2. Why is steam in industrial systems always wet?
Steam is always wet due to heat loss along long pipelines, pressure drops across valves, and changes in flow direction. Each pressure drop or expansion causes part of the steam to condense, reducing steam dryness and quality.

3. What harm does wet steam cause?
Wet steam causes water hammer, pipe vibration, valve erosion and sticking, reduced heat-transfer efficiency, and increased fuel consumption. Over time, it leads to faster equipment failure, higher maintenance costs, and unstable operation.

4. How is a Steam Separator different from a Steam Trap?
A steam separator removes water directly from the moving steam flow, while a steam trap only discharges water that has accumulated at low points. They do not replace each other but work together to make the steam system drier and safer.

5. Does installing a Steam Separator save energy?
Yes. By increasing steam dryness, a steam separator increases the useful energy per kilogram of steam. At 3 bar, theoretical calculations show the steam energy can increase by about 7%, reducing fuel consumption and shortening payback time.

XIII. Conclusion

A steam separator not only helps to:

• Dry steam
• Protect valves and equipment
• Reduce water hammer incidents

but also delivers significant energy and economic benefits.

If you are looking for a simple, effective, fast-payback solution for your steam system, a steam separator is the answer.

Contact DIVI for consultation on designing a Steam Separator tailored to your actual operating conditions.
Commitment: No efficiency – money back.