Energy saving, the key to compressor selection

When buying a compressor, the energy consumption cost of the compressor is crucial.  

There are many energy-saving measures that are feasible.  

Ensure that replaceable parts can be easily repaired.  

   Because the air compressor is the heart of the compressed air system, the selection of the appropriate compressor form, displacement and performance is necessary for the entire system. Therefore, before finalizing their preferred compressed air system supplier, most users usually have to consider the following factors:

      ◆ The manufacturer’s reputation and product reliability, as well as the performance record of the product in operation;   

◆ The life of the compressed air system and its components, including daily operation and the ability to cope with emergencies;  

  ◆ The quality of system components is closely related to the performance of the entire system;   

◆ Product features, including product performance, practicability or low operating cost, etc. 

  ◆ The initial investment and performance of the equipment, less maintenance and additional costs;   

◆ Environmental protection and safety issues, because they must comply with compulsory regulations, current industrial standards and the safest possible operating practices;  

  ◆ The relationship between the supplier and the manufacturer, the customer's confidence in them, expected performance and satisfaction with the equipment and its performance;

   ◆ After-sales service, including a complete maintenance network, can provide comprehensive product knowledge and support no matter where the customer is;  

  ◆ Lifetime cost of equipment, including system suppliers and the ability to provide competitive equipment, installation, maintenance and energy-saving measures;   

◆ The rate of return on investment, which is related to the ability of the equipment provider to supply systems and equipment, because the end user needs to pay for the asset value, operating efficiency, time-saving design and performance gains;   

Energy consumption 

  Assuming that the alternative compressor styles in this comparison are all electrically driven, some major aspects must be taken into consideration in the total energy consumption. These include electrical energy consumption, (costs/kWh) and additional costs indicated by the user for the highest load.     

As important as cost considerations are the main operating modes of the compressor. For example, does the compressor mainly meet full load, partial load or no-load working conditions, and the expected working (load) cycles or hours of compressor operation?     

Life cycle cost  

The total cost of buying and operating a typical compressor can be divided into the following four types:   

◆ Initial investment, which is mainly the cost of compressor equipment. 

  ◆ Installation, including foundation, measurement and assembly, pipeline and line installation. 

  ◆ Maintenance, including daily fluid and filter replacement, inspection and other regular maintenance measures to maintain the reliability and efficient operation of the device.  

◆ Energy consumption, this is the most important piece of the four costs, its quantity is more than three times the sum of the other three, and more than six times the initial investment cost. When choosing a compressor, energy cost is the most important factor.

Compressor selection  

A The choice of compressor supplier is usually the main consideration, while the choice of compressor device is relatively less important. There are a wide range of available compressor styles and design options, and each has its own unique operating characteristics. It is usually the responsibility of the air system designer to match the appropriate compressor to the project requirements. Because there are many differences in the appropriate pressure and displacement range

Compressor styles are applicable. There are several guidelines for selecting compressor styles that meet the design criteria (Table 1).  

For the sake of objective evaluation, it is assumed that the compressed gas needs to meet the following requirements:   

Compressor power range: 7.5 to 300kW  

Compressor displacement range: 0.8 to 62m3/min 

  Exhaust pressure: 0.4 to 1.2MPa  

After comparing the above principles with the available compressor style diagrams, the most appropriate choice is obviously the screw compressor (Figure 2).  

   Energy saving measures  

After meeting the standard compressor power, displacement and pressure requirements, we recommend that users consider the energy-saving measures listed below to maximize economic benefits.  

Energy-efficient motors. One of the most significant energy-saving measures that should be considered as part of the initial investment is the selection of high-efficiency motors. Now, these motors have two options: Energy Policy Act (recommended) motors or premium high-efficiency motors.  

At present, motors in the Energy Policy Act have compulsorily met the minimum efficiency standards determined by government regulations (Energy Policy Act-1997), and premium high-efficiency motors exceed the requirements of the Energy Policy Act for motor power cost efficiency by at least 1 to 2% (according to power Different) horizontal design. The payback period for premium high-efficiency motors is two years or less.  

Two-stage compressor. This type of compressor saves 10-30% of energy compared to a traditional single-stage compressor. It is also very economical that the payback period of a two-stage compressor does not exceed two years. 

  Control System. It should also be recognized to save energy by choosing the control system with the most complete operating method.  

Because careful control system selection seriously affects energy consumption, users or operators must pay attention to this vital choice.

   Heat recovery device. Many economic benefits can be recovered from the hot air produced in the compressed air production process. Because the cooling air passes through the aftercooler and the oil cooler, generally heat is stored in the cooling air. At least 90% of the recovered heat can be used for purposes such as support equipment, warehouse heating or other process heating. During the heating season, a typical 110kW air-cooled compressor unit equipped with a heat recovery system can save $2,600 per 1000 hours of operation per year. The payback period for heat recovery is usually less than one year.

Zero gas loss condensation trap. Another measure worth considering included in the initial investment is the zero gas loss condenser trap. This is specifically designed to reduce the loss of the compressed air system. This cost-effective equipment can not only repay the cost within 6 months, but sometimes does not need to be replaced in the existing large displacement compressor unit.  

   Reduce maintenance costs  

Although the current technological innovation has simplified the compressor design and reduced its components and connections, regular maintenance is still indispensable. New technologies have increased the performance, efficiency, and life of components that need to be maintained. In addition, routine maintenance procedures, such as filter and fluid replacement, now require less time than before.  

The following are the replaceable components that need to be considered in the total maintenance program related to life cycle costs.  

The air filter can provide a design with the following characteristics:   

◆ Better control of intake air quality.  

◆ The first line of defense against imported pollutants.  

◆ The reliability of the air end is improved.  

◆ Extend the life of the oil and gas separator, fluid and filter.  

◆ Increase the compressor displacement by 2% during the operating cycle.  

◆ Extend the air filter replacement cycle.  

◆ The payback period is less than three months  

   The advanced features that the oil and gas separator can provide, such as:  

  ◆ The oil carries high-quality exhaust with a concentration of less than 2ppm. 

  ◆ Lower fluid consumption.

   ◆ Low energy consumption due to reduced pressure drop.  

◆ Extended oil change interval.  

◆ The payback period is less than three months.  

   Water filter equipped with more advanced design components can bring the following advantages:   

◆ Water resistant.  

◆ Excellent fluid filtration. 

  ◆ Super protection for the air end.  

◆ Environmental protection.  

   Lubricant Choose advanced combination, which has the following advantages:  

  ◆ Better lubrication characteristics.  

◆ Not painted.  

◆ Environmental protection and easy to handle. 

  ◆ Longer fluid life.  

When choosing a new compressor, we need to focus most on energy saving.