Steam Metering: Common Installation Errors


Steam metering installations have specific installation requirements that if not followed can lead to inaccuracies in readings and poor reporting


Steam Meter

With ever increasing utility costs, carbon taxes and resource scarcity the importance of utility metering is now greater than ever. However correctly metering utilities within a manufacturing site is more complex that generally thought. Whether it be for Electric, Steam, Water, Gas or Air the requirements and installation conditions can have major effects on the effectiveness of your metering installation.

In this series of metering articles we explore some common examples of where metering installations are wrongly configured. In industry these types of mistakes can have major implications on the accuracy of your reporting. In this edition we explore steam metering.


So what needs to be considered and how could it affect your installation?


Steam Metering: Special Considerations? Pressure? Temperature? Superheated?

Saturated Steam

Steam Generated for use within the food and drinks manufacturing industry is typically generated as ‘saturated steam’. What does this mean? Saturated steam occurs when heat is added to water within the boiler (sensible heat) up until the waters boiling point. Additional heat then causes the water to vaporise (using latent heat). The result is saturated steam which at the steam systems temperature and pressure is in equilibrium with the water within the boiler.

Why is this significant?

 

The majority of modern vortex type steam meters use the fact that saturated steam at a certain temperature is always at a certain pressure. This means that meters are often installed with temperature compensation only. The meter then selects the relative steam pressure and calculates a resulting steam flow rate.

However a common mistake is installing this type of meter is placing the meter soon after a pressure reducing station. When the pressure of saturated steam is reduced the steam becomes superheated and the steam’s temperature pressure relationship no longer holds. This means that a standard steam meter will no longer read accurately.

What’s the solution?

The potential options are:

  • Install a meter with both temperature and pressure compensation, this will deal with both saturated and superheated steam
  • The other (and more cost effective solution) is to locate your meters a suitable length from a pressure reducing station, in the correct orientation and suitable straight length of pipework (which also requires special consideration).

This is just one of many criteria to consider when scoping your steam meter installation. Another common mistake is simply selecting your steam meter size according to the line size. This seems like the logical solution? If your steam lines are oversized for the duty of your plant (as is often the case with plants typically reducing their steam consumption over time) then the resulting low velocity in the main may result in your meter reading zero when there is steam flowing! The solution is to use the correctly sized meter bore for the steam velocity in your mains.

How we can help

Our core focus is improvement in identification, reduction and control of product losses, energy water and effluent. We have experience in scoping, selecting, installation and commissioning of all types of utility metering. Through well designed metering solutions we make sure the greatest savings are delivered and the best value is delivered to our client.


About Will Cooter

Will is a Chemical Engineer and associate member of the Icheme. His experience is primarily in process engineering and improvement in FMCG industries.