In this article, we would like to give you another idea for optimizing maintenance costs as well as energy optimization. Namely, the condition-oriented maintenance of compressed air generation. You can find reasons for this here.

Condition-based maintenance of compressed air generation: The motivation

The generation of compressed air is very expensive and should therefore be used as sparingly as possible. Only about 5 to 6 % of the electrical energy used is used for pressure boosting. The rest is mainly converted into waste heat. After the generated compressed air has been used, it is usually returned to the atmosphere. Thus, despite its immense advantages, compressed air generation is probably one of the most expensive as well as inefficient processes used. And for this reason, it is worthwhile to take a look at condition-oriented maintenance of compressed air generation. And this again in conjunction with the possible increase in energy efficiency.

Technically, this can be described as follows:

1. The monitoring devices on the motor/drive itself

Electrical monitoring

• Energy and current value recording in real time for possible optimization (CO2 balance)
• Determine state changes of the system based on the electrical direct parameters
• Detection of possible trend and load behavior during operation
• Maintenance measures can be planned for the condition (e.g. motor winding, bearing replacement)
• Detect and, if necessary, optimize changes in the condition of the power quality

Temperature monitoring

• State changes as symptom indicator
• Best suited for root cause analysis in combination with other indicators
• Recognition of possible trend behavior
• Damage prevention through timely shutdown

Mechanical monitoring

• The ultrasound gives an indication of the mechanical condition of the drive
• Changes in condition can be detected at an early stage
• Recognition of possible trend behavior
• Prevention of unplanned downtime
• Maintenance measures can be planned on the condition (cost and time optimization)

2. The monitoring devices on the compressor

Mechanical monitoring compressor (rolling bearings)

• The ultrasound gives an indication of the mechanical condition of the compressor
• Changes in condition can be detected at an early stage
• Prevention of unplanned downtime
• Maintenance measures can be planned on the condition (cost and time optimization)

Temperature monitoring compressor (oil temperature)

• Condition changes as symptom indicator (too little oil, thermostat defective, radiator defective)
• Best suited for root cause analysis in combination with other indicators
• Damage prevention through timely shutdown

3. The monitoring devices on the pressure accumulator

Ultrasound on the pressure line

• Flow monitoring (pressure build-up yes/no/when)
• Changes in condition can be detected at an early stage (e.g. diagnosis of a leakage)
• Recognition of possible trend and load behavior
• Best suited for root cause analysis in combination with other indicators
• Reduction of costs of unused compressed air and thus CO2-relevant

Pressure acquisition at the memory

• In combination with the pressure sensor after air treatment (differential pressure detection)
• Changes in condition can be detected at an early stage (e.g. dirty filter, leaks, icing)
• Permanently too fast discharges below a minimum indicate leakage or undersizing
• Permanently too slow discharges above a minimum indicate a possible oversizing
• Reduction of costs of unused compressed air and thus CO2-relevant

Note: The reduction of the mains pressure by 1bar already causes a saving of electrical energy by approx. 6-8%.

4. Redundancy control

To ensure production reliability, two or more compressors are often used. It might make sense to harmonize the operating hours via changeover control (aging and wear harmonization). In addition, if one of the two compressors fails or requires maintenance, the other can take over.

Conclusion in conjunction with an ISO50001 strategy:

• Efficiency can be increased and thus energy costs reduced
• Fast damage assessment
• Recognize if and when problems are brewing
• Logbooks, documents and proofs are automatically digitized as well
• A contribution is automatically made to CO2 reduction
• In the context of Energy Management System ISO50001 compliance
• PEX and OPEX reduce automatically
• The whole system is scalable – ROI occurs quickly
• There is no need for a maintenance strategy on the objects under consideration, as automated
• Sustainability and resource conservation are positively influenced
• The data can be balanced
• Maintenance is performed only when the condition indicates the need for it
• From predictive maintenance to condition-oriented and thus future-oriented maintenance

Imprint: This idea was developed jointly by Gubser Service and Camille Bauer Metrawatt.