Steam Solutions Comparison

What is the difference between an industrial (pressure) boiler and a steam generator? Boilers create steam by boiling water in a pressure vessel  by heating the water and creating creating molecules. As the water boils at its boiling point (the boiling temperature depends on the pressure generated) steam is obtained at the saturated pressure.  This type of steam making represent  older steam technology (because Tsaturated and Psaturated are linked for such a method to produce steam at a temperature different than the atmospheric pressure).

Steam generators on the other hand are modern devices with instant on-off features, steam velocity control features, independent back pressure control and significant high-temperature steam capability (without the need of pressure vessels or pressure unless required for the back pressure)

Traditional boilers yield saturated steam that can sometimes be mildly superheated.  Thus boiler steam may be wet and contain water droplets.  For example with  a boiler one needs a high 10 Bar and even then the saturation temperature is only 180°C  – even at 100 Bars the saturation temperature is only 311°C. Steam generators do not have to operate at high pressure for the high temperature- typically thus offer high-temperature dry-steam.

Steam Generators can operate at room pressure.  Thus one can get high temperatures in the steam-gas without use of unwieldy pressures.   High temperatures even up to 1300°C are obtained.

Industrial boilers have worked well but they are 19th and 20th century type technology machines with low efficiencies. They can reach 85% efficiency in many configurations (only at steady state which often takes long for boilers), but they still have significant drawbacks in temperature capability.  For boilers, very often, as the pressure rating increases the efficiency falls.  Steam generators, like the GHGA, MHGA, OAB or HGA type routinely offer over 95% efficiency even to 1000°C and beyond  (a temperature unimaginable for boiler steam).

  1. Temperature Limitations – Industrial boilers are temperature limited by pressure. To obtain higher temperatures, higher pressures are required. Not so for steam generators.
  2.  To operate at lower temperatures than rated, boilers typically sacrifice efficiency or safety.  Not so for steam generators.  As the pressure rating of a boiler increases, quite often its efficiency falls.
  3. Combustion Process – Nearly all large scale industrial boilers utilize the combustion process. This leads to CO2 and NOX production as well as fossil fuel consumption. Combustion processes typically result in low efficiencies and high energy losses.
  4. Safety – Pressure vessels can fail and explode (although this is rare as many boiler makers follow the best  practices). Low water levels can result in boiler overheating and potentially the explode. Gas leaks pose an inhalation danger as well as an explosion risk.
  5. Certifications  – Any boiler or pressure vessels require certifications and inspections. Review the boiler regulations for your state.
  6. Difficult to Use Boilers – Boiler operation is typically dependent on specific, trained individuals who are trained to read dials and follow numerous safety measures as per local code. Boilers are complicated.

Steam Generators use 21st century technology. No combustion or pressure vessels. The GHGA, MHGA, OAB and HGA patented technologies allow steam generators to operate with unparalleled efficiencies, saving you time, money and improving your process.

Steam Without the Wait

BoilerFreeTM technology allows nearly instant steam production. Most MHI steam generators produce super-heated in under a minute from a cold start (it can take a boiler many hours or days).  With a variety of outputs and configurations available, MHI likely has an energy efficient high-productivity solution for your steam application. Please contact MHI.

Feature One Atmosphere (OAB®) Steam or VHGA

This table comparison is for general properties

Steam Generator Models, Plasma Steam Models and Steam Chambers

Water Tube Steam Boilers Electric High Pressure Steam Boilers
Maximum Steam Temperature1 300-1300°C Standard. Choice of Models. Always high flow. No moisture. High performance. Sometimes up to 600°C with Economizer and Superheater.  Achieving steady state takes a long time for boilers. 134°C for 3 bar steam.
Delivery to Initial Start up.

How Versatile

Models are easily installed in a day and there is no anticipated wait for certifications to start.

Independent temperature, flow and pressure settings


Not at all versatile

Small units could be plug and play. Large units may require certification time.

Generally not versatile.

Efficiency >95% <85-90% (at steady state much lower otherwise) ~85-95% (at steady state much lower otherwise)
Idle Energy Waste Low (Choice of Continuous or On-off Steady-state steam) High Moderate
Non Steam Producing Energy Usage Time
(Start Up Time2)
Nearly Instant. Generally within a minute. 60+ Minutes. Becomes slower with higher pressures and volume requirements ~60 Minutes. Becomes slower with higher pressures and volumes. (Not including cool down and pressure release for autoclaves)
Suggested Inlet Temperature3 Tap 40-60°F 20-35°C
Capital Cost per Kg of Steam3 Low. Financing available when qualified. High Moderate. Depends on temperature/pressure required.
Operational Costs4 Low even up to 1300°C. High Low-Moderate
Unit Footprint Starting at 1’x 1’x 1′. Small and remotely locatable power panels. Depends on steam rate required. Large Depends on size and pressure requirements.
Plug & Play Operations Yes No No
Requires Boiler Certifications5 No Yes Yes
Downtime6 Low (Unit can be used for continuous steady-state steam). On account of the low foot print and modular designs the MHI-Never-Down Service™ is available for all steam units as applicable. Low-Moderate Low
Utilizes Combustion7 (Requires Ventilation) No Yes No
Energy Needed to produce 100 Kg/hr steam from cold start ~100 kWh @~350°C. Water at Room Temperature to Steam. ~150-200 kWh Equivalent (Including start up time consumption). Not always reported from room temperature water. ~150kWh Equivalent (Including start up time consumption). Not always reported from room temperature water.
Power Weight [Kg Equipment/(Kg/hr) of steam] for a 100kW Generator ~2 Kg per Kg/hr of steam. ~5 Kg per Kg/hr of steam (Weight increases with temperature/pressure)
Maximum Work Potential (Based on second law limitation) Base is 1 Bar 100C liquid water for all. 672 kJ/Kg for 500°C super-heated steam
1973 kJ/Kg for 1300°C superheated steam
755 kJ/Kg for 10 Bar saturated steam
1169 kJ/Kg at 100 Bar saturated steam
Generally not used for creating work.
Enthalpy (heat) Content 3489 kJ/Kg for 500°C super heated steam at 1 Bar 2777 kJ/Kg for 10 Bar saturated steam
Saturation steam temperature 180°C
2725 kJ/Kg for 3 Bar saturated steam
Saturation steam temperature 134°C
Running at Partial Capacity With MHI Electronic Controls, No loss of efficiency Significantly lower efficiencies, if model is capable Lower efficiencies
Air Contamination Effects Extremely high operation temperatures diminish effects of air Air contamination harms output No air contamination is allowed (strict)
Piping Losses Discrete, locatable units reduce necessary piping. The one atmosphere pipe can be better insulated and lighter. High pipeline pressure combined with long piping distances leads to heat loss and dangerous conditions in the event of pipe failure. Pipes can be heavy. High pipeline pressure combined with long piping distances leads to heat loss and dangerous conditions in the event of pipe failure. Pipes can be heavy.
How far can I run my pipe? Info-graphic.
Typical Improved Efficiencies (Energy) Application dependent – sometimes over 50% better
Improved Water Efficiency Application dependent – sometimes over 50% better
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