Why is air so bad for systems that rely on steam?

Many people incorrectly assume that air and steam is the same thing. However there are huge differences, especially in the level of energy. In fact, air will cause big issues with steam systems. As a result, it can be necessary to remove it. A discharge vent is a great option here, but you must think about the noise it can cause. You may also need a silencer to reduce the sound to a safe level.

The impact

The biggest issue with air in the steam system is it can dramatically reduce performance. It does this in two ways.

Firstly, it will lower the level of heat transfer. What typically happens is tiny air pockets will remain at the heat exchanger. Over time they create an insulating blanket because air is not a good conductor of heat. So, the amount of heat transferring from the steam can fall dramatically.

Secondly, air in the steam reduces the overall temperature. It can reduce it across the heat transfer surface. It can mean the system cannot achieve the correct process temperature. In turn that can mean processes that need to achieve a chemical or physical change won’t work.

How does it get in?

Air can get into systems in several ways. It is always there at start up, even if you try to begin by filling the whole system with steam. Sadly that will cause a vacuum and draw in air.

The main it gets in is via the feedwater. The water can readily absorb oxygen, nitrogen, and carbon dioxide, so it they will be present in solution. When it heats up, the fluid releases these gases and they go into the steam distribution system.

What to do?

The solution here is to vent the air to remove it from the system. A discharge vent with an automatic device is best here. There are manual ones but that puts more pressure on monitoring. There could also be a risk that the operator forgets to open the vent when necessary, compromising the system.

Ideally here you need the discharge to be as free as it possibly can be. That will maximise the amount of air removal. A good option is to have an automatic vent with a thermostat. It could detect the drop in temperature due to the presence of air and automatically vent it.

Think about silencing with a discharge vent

As you can see, venting the air is important to making steam systems function efficiently. However, the release of the gas can create a lot of noise. You need to think about this as the risk to people can be severe. In some cases the sound can be so loud it could damage the hearing of people nearby or cause major disruptions.

A solution is to use a silencer. They can be added to discharge vents and other parts of a system like pressure release valves. What they do is work to reduce the pressure and speed of the air flow. The goal is to bring them close to atmosphere. It will make it quieter when releasing air from the system.

At Ventx we excel at silencer design, manufacturing, installation, and more. As a result, clients can get a comprehensive service from us. We have very high standards and prioritise safety. So, if you need a silencer for a discharge vent, please contact us. We will be more than happy to assist you, regardless of how you use steam.