Leveraging Filter Technology to Increase Energy Savings in Your Plant

Situation

Like electricity and natural gas, compressed air is a utility used to perform work. Most plant managers are very conscious of the utility usage in manufacturing facilities because they can be a significant cost. Some challenges with compressed air:

1. Unlike electricity or natural gas, compressed air is produced on-site. The compressor derives its power from another source which is metered and measureable, obscuring the true costs by mixing them in with all the other uses of that utility.
   
   
2. Points of energy waste, such as compressed air leaks (as opposed to a gas leak or break in an electrical wire), will not make a smell or create a fire, will not shock anyone, and will probably go relatively unnoticed. For example, many times maintenance workers will crack a valve at the bottom of a filter bowl to make sure condensate can drain out. This might work, but the costs through waste associated with this practice can be extreme. As atmospheric conditions and seasons vary, the humidity in the air also changes, requiring constant adjustment. Donaldson UFM-D zero-air-loss automatic drains are designed to eliminate these losses and automatically handle the amount of condensate as it varies. 

What Is the Problem with Compressed Air Leaks?

Leaks that cumulatively add up to the equivalent surface area of a 0.25” hole can easily cost a plant an additional $15,000 per year in operating expense just through the extra compressed air generation required. These artificial uses of air also add to the amount of air that must flow through the pipes, increasing velocities and therefore pressure drop throughout the system. Basically, the leaks will cause both the piping and the filters to appear undersized, and undersized equipment makes it more difficult to supply the correct quantity of air to the end use without turning up the pressure. Each piece of point-of-use equipment will be extracting heat energy from the compressed air by allowing a certain volume of it to expand and drop in temperature. When something isn’t working correctly, the first response may be to turn up the pressure. However, it costs roughly 1% more input power for every 2 psi increase in system pressure, and this increased pressure exacerbates any leak losses that already exist. 

Solution

People typically increase their system pressure when their equipment is not getting the correct quantity or pressure of air. Plus, it is easy to do. A better approach is to look at the system between the compressor and point-of-use and minimize pressure losses in that area.

Filters contribute to the system pressure drop and should be examined. Donaldson filters are specifically designed to provide the lowest possible pressure drop, and they usually pay for themselves quickly through energy savings. For example,

• A 150 hp compressor requires approximately 120 kW electrical power
• A 2 psi pressure drop reduction will save up to 2% in energy consumption
• At 120 kW, 2 psi less pressure drop results in 2.4 kW less energy consumption
• At 8,000 operating hours per year and $0.10 per kW/h, this results in US$1,920/€1,517 per year

A 2 psi pressure drop reduction (US$1,920/€1,517 savings in this example) is readily achievable when switching many brands of compressed air filters to a Donaldson DF series filters using UltraPleat™ technology. The costs of the filters are very easily made up in the energy savings, and they provide the ultimate protection for plant equipment.