#4. Energy savings at manufacturing plant beyond LED, VFD and idling

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#4. Energy savings at manufacturing plant beyond LED, VFD and idling

A usually reasonable set energy audit recommendations includes LED lighting retrofit, VFDs on motors serving variable loads and reduction of idling time for all machines. These are expected energy efficiency measures nowadays. Complex energy audit goes deeper.

Complex energy audit considers how energy use affects core business – production, quality, scrap, employee productivity.

What else can be found? Let me share several less common recommendations and their impacts.

Reuse chilled water at plastic moulding

At a plastic moulding plant we found that production process required cooling at two different temperatures. Both cooling loads were connected to the same source of cold water at, obviously, lower temperature. Accordingly, for one load chilled water had to be warmed up to meet technological requirements. Recommended solution: reuse warm water after colder load for the second one.

Stable compressed air supply – stable quality and higher throughput at plastic moulding plant

Recommendation to retrofit compressed air plant are common place – tanks, conditioning, leaks, minimum necessary pressure. Owner at one plant was still not convinced: “We are too busy. Struggling to make new $500K machine work. It keeps producing scrap unpredictably.” Not a big surprise: new machine was installed at the dead end (!) of compressed air distribution pipe. Though pressure was adequate, volume was not when another machine up the line was using more air.

Audit recommended to create a compressed air piping loop and increase pipe diameter. Implementation of this measure ensured stable production in line with tough schedules imposed by automotive industry. Energy saving from lowering air pressure were just an icing on the cake.

Energy audit digs deeper to find savings

Compressed air retrofit reduced risk of product contamination at food plant

At a food processing plant we found that air compressor room was dirty and water was going on the floor all over it.

“That’s no problem. Product never enters this room. Compressed air does not come into contact with product, it’s used mainly to operate packaging line” – said maintenance manager. Audit brought to plant manager’s attention a simple observation that packaging machine exhausts compressed air in close proximity to unpacked product. A complex retrofit of compressor room was soon underway.

Optimization of refrigeration plant saved 34% of energy at food processor

Industrial refrigeration plant is an energy hungry complex set of machinery. It can reject the same amount of heat (‘produce the same amount of cold’) using different amounts of electricity depending on settings.

A typical refrigeration plant wastes 20-40% of energy.

Having efficient compressors does not guarantee efficient operation of the whole plant. The way fans, pumps and compressors are set to work together can make a 34% difference in energy consumption.

Energy audit can recommend energy efficient settings and operational procedures.

Lighting retrofit eliminated production bottleneck and saved CAPEX at industrial bakery

That was a curious case. Energy was not at top of plant manager’s mind: demand for their baked goods exceed their production capacity. Freezer was the bottleneck. Their product was shipped frozen and could not freeze as much as they could bake. Freezer was the bottleneck. Plant manager was working on CAPEX request to HQ for a bigger freezer. HQ was not supportive: rebuilding freezer would cause production interruption, while product was in demand. As a temporary measure plant sent a truckload of product to a 3rd party freezer for about $500 per truck, every day, every shift.

An express audit of the facility uncovered that their freezer had metal halide lighting. Effectively a 6kW heater within a freezer.

Long story short, an LED retrofit for this freezer eliminated the bottleneck and saved a truckload of cash: this project had a 3 day payback with no interruption for production.

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