Email this pageTypes of Steam and Their Applications
What are Some Applications for Steam?
Steam refers to matter in a gaseous state. Though it is not limited to steam generated from water, many different kinds of steam exist in the world, the term 'steam' is most commonly used to refer to the gaseous state of water.
Steam from water results when water is heated to the boiling point under a constant pressure, which causes it to vaporize. In recent years, the scope of the use of this 'steam generated from water' has expanded from use only in fields of industry to everyday household uses such as steam ovens and steam cleaners.
The main applications for steam can be roughly divided into heating / humidifying applications and motive / drive applications.
For the purposes of this article, we will divide the types of steam into categories from the viewpoint of the applications in which they are used.
Steam for Heating / Humidification
Positive Pressure Steam
This is the type of steam most typically used in plants / factories. Widely used for heating and humidification in equipment such as heat exchangers and steamers, it is normally used at pressures between 0.1 - 5 MPa (abs) and at temperatures of 110 - 250 °C.
In many cases steam is used in the saturated state, known as saturated steam, because the relationship between pressure and temperature is fixed and rapid heating through latent heating is possible. In the food processing industry, superheated steam is sometimes used as the heat source for cooking and drying / dehydrating. Superheated steam heated to 200 – 800 °C at atmospheric pressure is particularly easy to handle and is used in the steam ovens for household use on the market today.
Vacuum Steam
The use of steam at temperatures below 100 °C and at atmospheric pressure, which is conventionally used as a heat medium in the temperature range in which hot water is used, has grown rapidly in recent years.
When saturated steam is used in the same manner as positive pressure steam, the temperature of the steam can be quickly changed by adjusting the pressure, making it possible to achieve a precision in temperature control that is not possible with hot water. However a vacuum generation unit must be used in conjunction with the equipment, because merely reducing the pressure will not drop it to below atmospheric pressure.
Steam for Motive / Drive
This type of steam is used for propulsion (as a driving force), in applications such as steam turbines. An example of this that would have been familiar to most people many years ago is the steam locomotive, but in recent years the use of steam as a driving force in our immediate surroundings has become fairly rare. However, the development and evolution of technologies using steam as a driving force has continued up to the present time.
The steam turbine is a piece of equipment that is essential to a thermal electric power plant. In an effort to improve efficiency, progress is being made toward the use of steam at ever-higher pressures and temperatures. There are some thermal electric power plants that use 25 MPa (abs), 610 °C superheated, supercritical pressure steam in their turbines. In order to prevent damage to steam turbine equipment caused by the inflow of condensate, the use of moist steam is avoided and in most cases superheated steam is used. In nuclear power plants, however, the use of high temperature steam must be avoided, as it would cause problems with the material used in the turbine equipment, so high pressure saturated steam is typically used.
Distribution of Various Types of Steam
Click on the name of each type of steam to see a typical application for that type of steam.
Animations of Applications for Different Types of Steam
Steam for Heating / Humidification (Saturated): Shell and Tube Heat Exchanger
The steam that was used to raise the temperature of the product turns to condensate and is discharged from the steam trap
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Steam for Heating / Humidification (Superheated)
Compared with using hot air for heating, using saturated steam has the benefits of allowing for heating in an oxygen-free state and offering very high heating performance. Progress is being made in research toward developing this technology for commercially viable applications.
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Atmospheric Pressure Superheated Steam: Steam Oven for Household Use
Steam from water which is heated further until it becomes atmospheric pressure superheated steam at high temperatures of 100 °C and above transfers heat very well and offers excellent cooking performance. An additional characteristic of this superheated steam is its ease of handing due to the fact that it is at atmospheric pressure.
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Vacuum Steam (Saturated): Vacuum Steam Heating System (VM-H): Package Type
Compared with a hot water heating system, this system offers speedy, even heating, rapidly reaching the set temperature with no unevenness in temperature.
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Steam for Propulsion / Drive: Condensate/Steam Turbine Rotor
The drive force from the steam causes the fins to turn, which then causes the rotor on the attached power generator to rotate, and this rotation generates electricity.
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It's true that both saturated steam and superheated steam occur when liquid water undergoes a phase change and becomes a gas, yet the properties of these two types of steam differ from one another. In addition, there is a type of water called 'critical water,' which is neither steam nor water. Further discussion about the different properties of these types of steam can be found at Various States of Steam.
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