Technology

A plastics molding plant had engaged us to conduct an ‘on-site’ Energy Assessment of their facility. The annual ‘spend’ for electricity, natural gas, and water was about \$3.2 million for this modern 275,000 square foot, fully air-conditioned facility. During the Review, several opportunities were identified and delineated in lighting, HVAC, process ventilation, the water systems and energy supply contracts. However, the most significant savings were in their compressed air system.

Treating compressed air as a true utility and outsourcing the entire process is a growing trend in the industry. If a plant does not generate their own power, provide their own water or deliver their own natural gas, then why not treat compressed air requirements in the same manner? This article will use a recent project as a case study to show the benefits one factory received by making the decision to outsource compressed air like a utility.

Machine builders aiming to improve the energy efficiency of their machines tend to focus on using energy media other than pneumatics (typically electro-mechanical or hydraulic) since pneumatics, as traditionally applied, is viewed by some as inefficient due to factors like leakage and over-pressurization (i.e.: supplying a higher pressure in an actuator to accomplish a task which is endemic in practice). But they shouldn't, with its low cost of ownership, pneumatics when properly used remains a viable and many times preferable energy source for a given application. When generating and using compressed air, it's true that there are many places in the system where energy can be lost, however targeted measures within a comprehensive energy saving concept can prevent these losses and significantly reduce energy consumption at the machine level.

The PET industry is in a state of flux right now. A number of new bottle blowing facilities are being brought on-line. They are in the “discovery” phase right now as they realize how challenging the required compressed air systems are to manage – from an energy efficiency standpoint. The average high-volume stretch blow molder (SBM) working with PET usually has 2,000 to 4,000 horsepower of installed air compressors with the related energy costs running between \$1 to \$4 million per year. This typically represents 35-40% of the facilities’ total energy bill.

Compressed Air Best Practices interviewed Gregory Rhames, Asset Reliability Manager/Energy Manager at Verallia.

As background, Verallia is the packaging division of Saint-Gobain. Verallia employs 15,500 people globally and makes about 25 billion glass bottles and jars each year. We employ 350 people at Madera where we produce about 1 million wine, champagne and sake bottles per day.

Many passenger cars on roads in Germany contain efficiency concepts that make a considerable contribution to lowering emissions. Automotive manufacturers such as VW have gone even further than this, by applying efficiency strategies in their own value added chain. Because the benefits of pneumatics in automotive industry production processes have seen pneumatic actuation win over other drive technologies, efficient use of compressed air plays a key role in increasing energy efficiency.

Having set a goal to reduce their own energy intensity by 20 percent by the year 2020, Atlas Copco has also set the ambitious target for the energy consumption of the products they sell. Using the Global Reporting Index as the way to establish metrics, there is real substance behind the sustainability program at Atlas Copco.

The U.S. Department of Energy estimates that air compressors use as much as 10% of all electricity generated in the United States. Further, the DOE calculates that as much as 50% of this energy is wasted. Compressed air leaks alone account for 25-30% of compressed air use.

While control storage was originally an integral component of a reciprocating air compressor installation, this article will only briefly explore that application. The content of this article will focus instead on rotary screw installations since the rotary screw air compressor has essentially replaced the reciprocating as the compressor of choice in industrial applications. It should also be noted that in compressed air systems where reciprocating and rotary screw air compressors are operating together, control storage should always be utilized.

One of the many tasks in assessing a compressed air system supply side is to analyze the air treatment system for appropriateness and efficiency. Most compressed air systems have one or more air dryers in place to remove the water vapor contained in the compressed air produced by the system air compressors. If there is no air dryer, the normally hot saturated air produced by the air compressors will cool in downstream system components, and condensed water will form in pressurized system pipework.