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Basics of Steam

Heating with Steam

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Steam is one of the most common and effective heat transfer mediums used in industry, but it is not the only medium available. Other fluids such as hot water and oil are also used for indirect heating in heat exchangers. The following series of articles will focus on the advantages of using steam compared to hot water or oil for heating.

Advantages of Steam Heating

Heating with Hot Water or Oil

Heat transfer from a liquid medium such as hot water or oil utilizes the medium’s sensible heat. The liquid is supplied at elevated temperatures to the heat exchanger. As the liquid gives off thermal energy, its temperature decreases, exiting the exchanger at a lower temperature. The amount of energy released per unit of heat transfer medium is relatively low (typically around 17 kcal/kg, or 30 Btu/lb).

Hot water and oil are supplied to the heat exchanger at high temperatures and exit the heat exchanger at lower temperatures.

Hot water and oil do their job by lowering their own temperatures.

Heating with Steam

Steam is supplied in a gaseous state to the heat exchanger. Heat transfer with saturated steam utilizes the latent heat of steam, releasing a large amount of energy as it condenses (changes to the liquid state). Liquid condensate exits the heat exchanger at close to saturated steam temperatures. The amount of energy released per unit of steam is high (up to 539 kcal/kg, or 970 Btu/lb, and higher with vacuum steam).

 

Steam is supplied to the heat exchanger in a gaseous state, changes to a liquid state (condensate) and comes out of the heat exchanger。

Vapor does its job by changing its form from gas to liquid.

Summary of Benefits

Utilizing latent heat (steam heating) for heat transfer is far more effective than utilizing sensible heat (hot water or oil heating), as a much higher amount of energy is released in a shorter period of time. This offers the following benefits:

Property Advantage
Rapid even heating through latent heat transfer Improved product quality and productivity
Pressure can control temperature Temperature can be quickly and precisely established
High heat transfer coefficient Smaller required heat transfer surface area, enabling reduced initial equipment outlay

To understand the reasons behind these properties and advantages, read the next article on the Steam Heating Mechanism.