By Martin Ochieng
The information from this article draws from data collected by a real-time energy monitoring system on a client’s premises. The audit team was able to identify a couple of issues based on the operation of a 37kW load-unload compressor with an inbuilt dryer. Data collection and analysis was made possible through the use of specialized tools developed for Eenovators Ltd.’s Eagles program.
During routine analysis of operational characteristics of the compressor installed on the client’s premises, the team identified two issues in the machine’s demand curve.
- The compressor spent a significantly lower time in the unloaded state than it did in the loaded state.
- The unloading cycle dropped from a little over 40kW to just a little under 20kW.
This behavior meant that the compressor was not allowed to unload to a lower level at ideally approximately 10% of peak demand. The operating pressure band at the time only allowed the unload cycle to drop to only 50% of the peak demand. The initial pressure band range was a minimum of 6.8br and a maximum of 7.3 bar.
The Audit team recommended an initial adjustment of the lower limit for the pressure band from 6.8 bar to 6.3 bar. This would move the pressure band’s range from 0.5 bar to 1 bar. The team anticipated that this modification would increase the unload time allowing the compressor to unload to a lower demand value during the cycle. The client agreed with this assessment and opted to make this change at the beginning of October 2020 to identify the potential change in operating energy consumption.
The new pressure band still provided sufficient compressed air for all the machines operation.
As indicated on the image, October saw a consistent drop in energy consumption across the whole month. The Eagles energy management portal was able to identify this drop as well through the monthly report as indicated below.
Although the team was not able to acquire production data over this period to undertake proper measurement and verification, the team noted that the general energy consumption for the whole facility increased. Drawing from audit analysis that showed good correlation between total energy consumption and production, it is plausible for us to assume that production also increased across the facility. This assertion helps draw the conclusion that energy consumption at the compressor should have increased as well making the actual savings even higher than can be indicated by changes in consumption but I digress.
Still the data shows a reduction in energy consumption of over 1 MWh, whose value stands at a little under $200. Over a year, these savings will approach $2,400 which is quite impressive for a measure that doesn’t need any investment.