Recovering Steam Clouds and Waste Heat

Steam Clouds: Energy Going to Waste

Clouds of steam vapor are a common sight in some process plants. These clouds are often considered to be an inevitable by-product of steam heating processes. However, in the least sense, steam clouds are an eyesore, and worse they can create a safety issue from subsequent algae growth or freezing of falling water. Vapor clouds can also make a plant hot and unpleasant if vented internally. On top of this, what may be missed is that they constitute potentially valuable heat energy going to waste.

When used in heating processes, steam loses its latent heat energy and condenses. The resultant condensate is usually over 100°C [212°F], and may contain as much as 30% of the heat energy originally held by steam. When flash steam from condensate is vented to atmosphere, this valuable heat energy, much of which can be recoverable, goes to waste.

If Condensate is Not Collected

If Condensate is Collected

Some heating processes that use direct steam injection, such as steamers, autoclaves, sterilizers, and rubber vulcanizers, need to release steam from their systems. These vents may provide an opportunity for energy use rather than venting to atmosphere.

By collecting and reusing viable heat from condensate and steam, plants can reduce unwanted steam clouds, save energy, and lower operating costs—all at the same time!

Below are some common examples of steam clouds in steam-using plants.

Steam Vented to Atmosphere from a Condensate Collection Tank

Steam billowing from a condensate collection tank is a sign that although condensate is being properly collected in the tank, excess heat is escaping from the condensate and venting to waste.

Plants with this problem can implement one of the following countermeasures to make better use of the excess heat energy.

Steam Clouds Emitted from the Boiler

There are some plants where boiler steam must be made even if there is not sufficient use for all of it. In such cases, some of this steam is vented to avoid pressure build-up. Examples include some plants burning wood chips (in the absence of an incinerator).

Whenever such boilers create more steam than is needed for process applications, plant managers should consider using the steam to generate power. This extra power can be used within the plant or sold back to the electric grid.

Steam Clouds Billowing from a Vent Pipe

In some steam systems where condensate is recovered, clouds of steam can occasionally be seen billowing from vent pipes acting as flash vessels.

Vent pipes lower the pressure on the outlet end of steam traps, thus enabling condensate to be pumped and traps from other low-pressure equipment to drain into those return lines. Flash steam billowing out of these vents can be collected and reused.

Steam Clouds Emitted from Condensate Drained into a Pit

Perhaps the boiler is too far away, or there is not enough condensate to justify return, or the condensate's pressure level is too low…Whatever the reason, many plants choose to waste condensate and to drain rather than recollect it.