Cost Saving Opportunities for Compressors
28 червня, 2022
In many compressed air installations there are often significant and unutilized cost-saving possibilities. Learn more on how to save on compressor running costs here.
Understanding the total cost of compressed air
When discussing the cost of compressed air, it's worth mentioning that electrical energy makes up most (80%) of your compressor-related expenses. As a result, many compressed air installations offer significant energy-saving possibilities including energy recovery, pressure reduction, leakage reduction, regulation systems, and controls and features. You'll also want to pay attention to compressor size.
Determining the cost of compressed air
Investment costs are fixed and include the purchase price, infrastructure expenses, installation and insurance. Investment costs are determined by both compressed air quality level and depreciation period. Energy expenses include annual operating time, degree of load/unload utilization, and the unit energy cost.
Planning your system
When investing in new equipment, consider both current needs and future growth. Don’t overlook factors like environmental regulations, energy efficiency, and production demands.
In industries that rely heavily on compressed air, optimized operations are essential, especially as production conditions evolve. An unbiased analysis of your needs can help cut costs and ensure your air supply matches demand while leaving room to scale efficiently.
Components of a compressed air system
Below is a list of various components you'll encounter and how they impact the overall cost of compressed air systems.
| Component | Description |
|---|---|
| Air compressors | The core machine. The initial cost is minimal compared to the total cost of ownership. Since energy is the main expense, choosing the most efficient model is crucial. |
| Dryers and filters | Essential for air quality in sensitive sectors like food and pharmaceuticals. Must be tailored to industry standards. |
| Drains | Intelligent zero-loss drains save energy by discharging condensate only when necessary, unlike timer drains which waste energy. |
| Piping | Proper piping prevents restrictions, pressure drops, and minimizes air leakage. |
| Air receiver tanks | Appropriately sized tanks reduce false demand, pressure changes, and limit the need for extra compressors. |
| Air leakage | Continuous monitoring and leak detection are vital to maintain efficiency and reduce costly losses. |
| Central controller | In multi-compressor systems, central controllers optimize performance by regulating pressure bands, capacity, and speed. |
| Energy recovery | Waste heat from compressors can be repurposed for heating rooms, water, or processes, boosting energy efficiency. |
The power requirement concept
When making calculations, applying the overall power requirement concept is important. All components involved in a compressor installation should be considered, including inlet filters, fans, dryers, separators, and energy recovery. To compare options, it's best to use International Organization for Standardization (ISO) standards.
Working pressure
Is necessary to make a correct calculation of working pressure because this directly affects power requirements. Higher pressure means more electricity consumption. In fact, each 1 bar increment requires around 8% of power. Increasing the working pressure to compensate for pressure drop always results in impaired efficiency.
Generally, these pressure drops occur due to an inadequate pipe system or clogged filters. It's advised to investigate these factors before increasing compressor pressure. With installations fitted with several filters, the pressure drop can be significant and costly if such maintenance concerns aren't addressed.
In many installations it is not possible to implement large pressure reductions. However, the use of modern regulation equipment allows pressure to be realistically lowered by 0.5 bar. This method creates a slight power savings. While seemingly insignificant, this reduction impacts annual expenses.
How to save on energy costs
As mentioned above, energy expenses are the dominating factor of the overall cost of compressed air. In fact, they can make up to 80% of owning and running a compressed air system. Therefore, it's important to focus on the most efficient solutions to meet your demands.
Although the most advanced equipment comes with higher initial investment costs, it's usually worth it for overall savings. An ideal situation is when a compressor's capacity meets your application's air consumption. There's also variable speed drive (VSD) equipment to meet different pressure needs.
Optimizing equipment
Most compressors come equipped with onboard controls and regulation systems. If you run more than one machine, you can also add smart monitoring system. Doing so will help optimize your entire system and ensure you're operating at peak performance. With this, motor speed regulation is a popular energy-saving method due to its substantial potential. Some monitoring tools can also pinpoint areas of inefficiency.
This information is helpful in determining leakage, worn equipment, poor filtration, and improperly configured components. As pointed out earlier, these maintenance issues can increase the overall cost of compressed air systems.
Frequently, leakage can amount to 20% of compressed air flow production. Leakage is also proportional to working pressure, which is why one method is to repair leaking equipment and lower the working pressure. Reducing pressure by only 0.3 bar reduces leakage by 4%. If the leakage in an installation of 100 m3/min is 12%, this reduction represents a savings of approximately 3 kW.
You'll also want to consider when you actually use your equipment. If a small amount of compressed air is used during nights and weekends, you may want to install a small compressor for these times. This segmentation can be achieved with shut-off valves.
If a particular application needs a different working pressure, you'll need to determine whether centralized or split production makes sense. Sectioning off your compressed air network is also useful for segmenting between high and low peak times. Such planning should be based on airflow measurements.
Regulating your system
Using a modern master control system, as described above, the compressor central plant can run optimally for different situations. Selecting the right regulation method encourages energy savings with lower overall system pressure and optimal utilization. These controls can also reduce downtime by spreading workload evenly.
Also, central control allows you to program automatic pressure reductions during off-peak times, like nights and weekends. As compressed air consumption is rarely constant, the compressor installation should have a versatile design. A combination of compressors with different capacities and speed controlled monitors should be implemented.
Energy recovery
It's possible to utilize recovered air compressor waste energy to fully or partially replace external electricity, gas, or oil for heat. Decisive factors include energy cost in €/ kWh, the degree of utilization, and the amount of additional investment necessary.
A well-planned waste energy recovery system often produces a payback within 1-3 years. Over 90% of the power supplied to the compressor can be recovered in the form of valuable heat. The temperature level of the recovered energy determines possible application areas and, therefore, its value.
The highest degree of efficiency is generally obtained from water-cooled installations. This works when the compressor installation's hot cooling water outlet is connected to equipment demanding heat. For example, the existing heating boiler's return circuit.
Waste energy recovery can be utilized year round. Different compressor designs have different prerequisites. In some situations requiring a large and peaking heat flow, long heat transport distances, or varying requirements, you can also sell recovered energy.
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