Industrial Utility Efficiency    

Metals

Manufacturers familiar with the U.S. Environmental Protection Agency (EPA) ENERGY STAR® Energy Treasure Hunts initiative know it’s a great way to save energy and natural resources – as long as it’s done right – which is why some are turning to perhaps their best asset to achieve success: their unionized workforce.
One topic up for discussion in the metal fabrication industry is the assist gas used for laser cutting. The assist gas is fed into the laser head, and surrounds the laser as it cuts the work piece. The assist gas is intended to facilitate a smoother cut, increase cutting speeds and productivity, and to prevent discoloration, oxidation, scale, burred edges and other defects that can arise from the hot cutting temperatures. Since Nitrogen is an inert gas, it is used as an assist gas on many laser cutting systems to prevent oxygen from coming into contact with the metal while it’s being cut. Nitrogen is supplied to users in traditional cylinders, and with on-site nitrogen generation.
Reverse pulse type dust collectors often represent a challenge to compressed air energy efficiency, and sometimes throw a wrench into the works by causing huge air pressure fluctuations, high transient flows and just plain large leaks. This article discusses this type of dust collector, often installed in food processing plants, and gives some real-life examples of problematic installations. Some suggested measures are mentioned to ensure your dust collectors keep running in a trouble-free manner.
With an eye toward strengthening its competitive edge, GKN opted for a new approach for the compressed air it uses to power metal molding machines in addition to a variety of other applications at its manufacturing facility. After careful analysis and planning with the Total Equipment Company located in Coraopolis, Pennsylvania, GKN opted to move beyond its aging compressed air system – and instead – outsource compressed air as a utility. Doing so allowed it to free up valuable floor space, while also achieving peace of mind since it can now count on a fixed cost for a reliable compressed air supply for years to come.
Plant personnel had experienced ongoing problems with its process grinder performance due to unstable compressed air pressure. This created potential problems in terms of product quality. Grinders do not work properly without the proper pressure. Additionally, plant staff wanted to address these concerns, prior to a proposed 30% increase in production, and suggested raising the header pressure from the current operating pressure of 98 psig to 125 psig. The thought behind this was if the pressure from the header to the grinder process was dropping to 63 psig, then raising the pressure to the process would give the grinders enough pressure to work through higher peak production times.  
The steel mill in this article is a rolling “minimill,” a facility that melts scrap recycled steel and produces rebar for the construction industry. It fits in SIC code 3310. There are many plants like this all over the world, providing an environmentally sound service and product for their local community. They recycle waste steel from local sources and support local infrastructure projects with rebar, using electricity generated locally.
All industrial facilities use some form of compressed air, and in most, the air compressors consume a significant amount of the total energy bill. A facility with a good energy management system is likely to identify their compressed air system as a significant energy user (SEU). If the facility were using an energy management standard, such as ISO 50001, they would be required to assess and track the energy consumption of all their SEU’s. In the case of the metal processing facility, they were measuring the output of more than 250 devices within the plant, including building heaters, RTU’s, dust collectors, and also tracking the consumption of their electricity, natural gas and water. 
Chicago Heights Steel, Chicago Heights, Ill., leveraged an advanced data monitoring system and adopted a demand-based compressor air management approach to save 2.5 million kWh and $215,037 per year in energy costs. With an incentive of $188, 714 from local utility ComEd, the project delivered a payback of 2.4 months.
Factory lasers use nitrogen right at the cutting point on the metal because the high temperatures used in the process can often cause oxidation. When oxidation occurs, the metal pieces being cut can be damaged, as can the tooling creating the cut. Structural damage or inaccurate cuts can make parts weak and render them useless. The use of nitrogen at the point of contact from laser to metal removes oxygen from the cutting area and helps cool the die as it cuts, thus preventing oxidation. This prevention improves the quality of the final products, produces less scrap metal and cuts back on the reworking of pieces.
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.
While late summer may not be the time of year many of us think about heat recovery, the potential for energy savings in compressed air systems should be on our minds year-round. For those involved with the compressed air systems within International Wire Group’s facilities, energy savings is on their minds each day. This culture of continuous improvement has everyone on the lookout for savings wherever possible.