Industrial Utility Efficiency
The purpose of this article is to show there isn’t always a proportionally linear relationship between what happens with flow reductions on the demand side of a compressed air system - and what happens with the energy consumption in the air compressor room. Optimizing an entire compressed air system requires precise knowledge of the supply side, how compressed air is used in the process itself and how those two relate together.
One observation I’ve made from 30 years of working with compressed air systems is to never underestimate the ingenuity of plant personnel when it comes to misapplying compressed air. We see something new in virtually every plant we visit, but one of the more common problems we encounter involves the use of expensive air for bearing cooling.
This major food manufacturing plant in the Midwest uses compressed air and onsite nitrogen generation to operate multiple snack production and packaging lines. The plant spends an estimated \$430,344 annually on energy to operate its compressed air system based on an average rate of 4.5 cents per kWh.
On a recent project, at a polyethylene terephthalate (PET) blow-mold and filling operation, a very effective measurement plan resulted in a full synchronization of the supply side air to blow molds with significant reduction in total air use and increases in productivity and quality.
Air Operated Double Diaphragm (AODD) Pumps are popular and versatile. Often, they also offer an excellent opportunity to lower the demand for compressed air, especially given the latest advances in controls and the energy savings to be realized.
In this ongoing column, we share insights into technologies that offer the opportunity to affordably and easily lower compressed air use and generate energy savings – all while achieving relatively quick payback. But finding these technologies on the production floor isn’t always easy or straightforward. In fact, there are many times when a technological solution is far less than obvious. Such is the case with cooling of control enclosures, which represent a significant area for high-energy savings with little upfront investment. Here is some out-of-the-box thinking… check that… inside-the-box thinking… for optimizing control of enclosure cooling and coming out ahead.
When the 18th Century Italian physicist Giovanni Venturi discovered when air is forced through a conical nozzle its velocity increases as the pressure decreases, neither he nor anyone could conceive it would ultimately spawn one of the most used and most highly controversial products in the industry today- the Venturi vacuum generator (aka, ejector).
Spruce Products Limited operates with five separate compressed air systems in their various buildings. A few years ago a sharp-eyed air compressor service representative noticed the screw compressors on site had less than optimal loading to operating hours ratios. Recognizing this was a problem, he suggested the company get in touch with their local power utility for a free compressed air scoping assessment. As a result, SPL has optimized two of their compressed air systems to-date, saving significant operating costs. One system is operating at 86% less energy consumption than previous levels.
A flour based frozen foods manufacturer orders a compressed air efficiency audit. The audit establishes the cost of compressed air at \$0.27/1000 cubic feet. The study finds the 116 pulse jet dust collectors represent the greatest opportunity for compressed air demand reduction and energy cost savings. A dust collector optimization study/service is suggested and the customer agrees to proceed. In this facility, pulse jet dust collectors are used to filter dust from raw materials entering the plant, for conveying and mixing of ingredients, and for the final packaged finished products leaving the plant.
In the last ten years, the design of pneumatic systems has changed dramatically, mainly due to developments in the technologies that create them. Pneumatic manufacturers’ online tools for sizing components have evolved, the fieldbus systems are ever-changing, component designs are constantly improving, and network devices such as the Industrial Internet of Things (IIoT) have reshaped the industry. All these advances play a large role in optimizing the efficiency of pneumatic systems, but the age-old practice of routine maintenance must not be overlooked. This article will focus on proper air compressor sizing, proper pneumatic component sizing and predictable preventative maintenance.
In this series we covered some very common issues in the Compressed Air Generation or “Supply Side” with regard to misapplying some capacity controls and installing different types of air compressors with piping and/ or orientation. These can preclude any reduction in compressed air demand on the production side from effectively translating lower air usage into a commensurate level input energy.
