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).
In this article, we will provide detail on the characteristics of the baseline system and then share the energy-saving work identified in two projects. These two projects represent work which can be performed by the maintenance teams in every plant. These are also project opportunities we find in almost every plant we visit. The two projects are to (1) repair/replace condensate drains wasting compressed air and (2) to perform a compressed air leak survey.
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.
One of the most common problems in plants is low air pressure. One of the most common solutions is to purchase new air compressors. Often this advice leads to a poor return on investment with the company’s hard-earned money. Often the issues are related to demand, distribution, or both. Solving the wrong problem can be expensive from a capital and operating cost perspective. Determining root cause analysis may cost more up front, but will save tens if not hundreds of thousands of dollars long term.
A zinc producer spends an estimated \$516,000 annually on electricity to operate the air compressors in a compressed air system at its north American plant. The current average electric rate, at this plant, is 5 cents per kWh, and the compressed air system operates 8,760 hours per year. This system assessment recommended a group of projects able to reduce these energy costs by fifty-one percent (51%) to an annualized \$270,000. The simple payback of the project was 15 months – without taking into account potential incentive dollars from the local utility.
Great Plains has carved a global reputation for producing world-class seeding equipment since it first opened its doors in 1976. Great Plains manufactures a range of products from grain drills and planters, to compact drills and tillage equipment. They have established an international business built on expertise, knowledge and a commitment to producing products meeting the rigorous demands of the agricultural sector.
A meat processor, located in Canada, hired a consultant to assess their compressed air system as part of a company-wide energy conservation effort. The assessment and analysis showed, despite having a modern compressed air system using a VSD air compressor and pressure/flow control, the system was running inefficiently and had significant levels of leakage and inappropriate use.
An electronics manufacturer with a very large compressed air system recently had a compressed air audit done in their plant to assess system efficiency. The audit discovered the system had been designed to be extremely efficient, yet some previously undetected problems were causing less than optimal operation. Despite being located in a tropical environment, this plant utilizes heat recovery to help reduce the overall energy consumption.
Parrheim Foods, a division of Parrish and Heimbecker, is an innovative starch, protein and fiber mill situated in Saskatoon, Saskatchewan, Canada. The plant has improved system efficiency and reduced production problems by addressing some problems with the consumption of compressed air by their reverse pulse baghouse cleaning operations. This effort has allowed them to turn off one of their 100 hp air compressors, saving significant electricity costs.