6 Benefits of condensate recovery systems in boilers and steam plants

Steam is a common and most efficient medium for transporting heat in most industrial processes and plants. Here we explain the benefits of using condensate recovery systems in steam plants and boilers.

Plant engineers live under the constant pressure of having to look for cost reduction options in their facilities and to implement new ideas to improve the performance of their industrial steam systems. It is now more than ever a priority for steam users to make the best possible use of the energy and hot water in steam, therefore efficient condensate recovery is essential.

Condensate recovery systems offer several advantages. Energy is saved and fuel costs are reduced, the costs of water and its chemical treatment are reduced and discharges are reduced.

Why is condensate recovery in boilers and steam plants important?

The return of condensate to the boiler feed tank is recognized as the most effective way to improve the efficiency of the steam plant. Formed by condensed steam, liquid condensate must be drained from pipes and equipment to avoid the risk of water hammer.

Water hammer is a hazard in poorly drained steam distribution lines, when condensate collects and forms a solid pocket of water. This water cannot be compressed, unlike steam, and thus can cause damage when carried away by steam at high speed.

Condensate also contains about a quarter of the energy of the steam from which it comes. Allowing condensate to drain down the drain wastes valuable energy and water; therefore, most steam system plants recognize that condensate is a valuable resource. There are fewer and fewer industries that do not have some type of condensate recovery system, but the truth is that there are still many plants where much more could be done.

The following graph   shows the heat content of steam and condensate at the same pressure, from this it can be seen that the condensate contains about a quarter of the energy that the steam it comes from has.

There are applications where the condensate is not returned to the boiler room for operational reasons – either because steam is injected into the final product, for example in animal feed factories or direct steam injection in the processing of food, or because there is a risk that the condensate is contaminated and could damage the boiler.

Typical examples could be chemical treatments, dyes or food processing, where food particles could enter the condensate recovery system. However, even in these systems, the condensate could be recovered by installing pollution detection systems or heat exchange systems to avoid contamination of the boiler.

The figure shows a condensate recovery system in boilers and steam plants. Scheme showing the steam and condensate loop with recovery of the condensate to return to the boiler feed tank.

6 Benefits of condensate recovery systems in boilers and steam plants

Condensate is a valuable resource and recovery, even of small amounts, is economically justifiable.

1.- Reduction of fuel costs:

Typically, condensate contains about 25% of the usable energy of the steam from which it comes. Returning it to the boiler feed tank can save thousands of dollars per year in energy alone. If we use the condensate to heat the boiler feed water, the boiler will need much less energy to convert the water into steam. In other words, it will take less fuel to generate steam from hot water rather than from using cold water. Every 6 ° C increase in feedwater temperature achieved using “free” energy equates to a fuel savings of approximately 1%.

2.- Energy saving:

One of the great advantages of boiler condensate recovery systems is that the condensate is distilled water with a little total dissolved solid (TDS). If more condensate is returned to the feed tank, the need for boiler blowdown is reduced, which is done to reduce the concentration of dissolved solids in the boiler. Therefore, in this way, the energy loss of the boiler during the purge process is reduced.

3.- Reduction in water costs:

The condensate that is not returned and is not reused must be replaced by water from the network. This recharge will produce an additional cost of water. If you have a condensate recovery system, the benefit will come from a significant reduction in your water bill.

4.- Reduction of the costs of chemical treatments:

Reusing as much condensate as possible reduces the need to add expensive chemicals for water treatment.

5.- Reduction of waste costs:

In Spain, it is forbidden to pour water above 40ºC into public sewers, as it is harmful to the environment and can damage pipes. Condensate above this temperature must be cooled if it is to be discharged down the drain, which could incur additional costs of producing steam in industry.

6.- Elimination of steam plumes:

Steam systems that allow condensate to flash back into steam can create steam plumes that, in addition to being a waste of energy and water, are visible. This potentially presents a bad image to the outside world of an organization that does not respect the environment.

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