Energy cost reduction at industrial refrigeration plant

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Energy cost reduction at industrial refrigeration plant 2019-07-23T11:20:59-05:00

Project Description

Situation

Refrigeration plant is the major electricity user at food manufacturing plants. Our client – a food processing plant in Brampton, Ontario – runs 200hp and 100hp fixed-speed Frick compressors in ammonia refrigeration system with total capacity of 360hp. This plant supports production process, freezer and two coolers.

During energy audit we have identified several opportunities to reduce energy consumption through change of set points and operational procedures as well through installation of VFDs on condenser fans.

When client saw estimated effect of suggested changes on energy cost, a decision to go ahead came easy.

Project

Working in close cooperation with maintenance team, within two months of intense we have implemented all previously planned measures, improved compressor sequencing and identified several unnoticed fan and sensor failures.

Direct energy savings exceeded expectations by 2x

We estimate achieved mean value of annual savings at 374,000 kWh; approximately double we projected.

To calculate this number, we logged power draw by all components of the refrigeration plant for 2 weeks before and after the project, built normalized baselines through regression analysis, compared their forecasts and introduced severe conservative adjustments.

We have chosen to introduce adjustments worth 40% of calculated annual savings because, we can’t determine the exact number without measurement during summer.

Power draw reduction resulting from optimization at industrial refrigeration plant

Even without normalization massive power reduction is visible: graph shows total power consumption by refrigeration plant before (light blue line) and after (right side of dark line).

Savings are visible

When we started work in February, plant routinely run two compressors during production. In May, after optimization, plant run production on bigger compressor and sustained cooling load with a smaller one. Client has started using both compressors during production only by the end of June.

Financial effect of optimization – one week of plant work

At current electricity tariffs, 400,000 kWh cost about $50,000. These savings go directly to profit. To generate the same profit with the current gross profit margin of 5% this plant will need to ship $50,000/0.05= $1 mln worth of product. It’s more than a week of work of the whole plant.

This project was completed under framework for our Industrial Refrigeration Optimization service.