How to Choose Suitable Air Compressor Model and Type?

When you are ready to buy an air compressor, first of all, you should determine the working pressure needed at the air end, plus 1-2 bar margin, and then choose the pressure of the air compressor (the margin is to consider the pressure loss from the installation place of the air compressor to the actual distance of the air end piping

 

 

Selection Elements

1. Compressed air applications

2. Minimum operating pressure

3. Demand air volume of tip and off-peak. If the difference between the highest and lowest use pressure reaches 3 bar, it is necessary to consider the “high and low pressure diversion”, and then according to the change of the burden of the tip and the off-peak to choose different models of air compressors, such as “base load” using centrifugal (single machine > 75CMM) or spiral ( For “base load”, use centrifugal type (single unit >75CMM) or screw type (single unit <60CMM): for “variable load”, use high pressure air compressor with large air storage tank to cope with the load.

4. According to different gas quality selection and configuration of different forms and grades of dryers and precision filters, too good quality waste of energy, insufficient quality affect the process, must be carefully considered.

5. The control technology of air compressor is changing day by day, and the technologies of “multi-machine chain”, “frequency conversion” and “remote monitoring” can effectively inhibit centrifugal-type BOV and spiral-type empty car waste (saving electricity cost by 25-40%), reduce spare capacity and investment (15-30%), stabilize supply pressure (positive or negative 1 bar), and stabilize the air pressure (positive or negative 1 bar). (saving 25-40% of electricity cost), reduce the spare machine capacity and investment (15-30%), stabilize the gas supply pressure (± 0.1 bar).

6. Operational efficiency should not only be compared to the nominal horsepower and airflow in the catalog, but also to the actual “performance curve” and “airflow per horse”

7. The installation takes into account the size of the equipment room space, ventilation conditions, noise insulation, waste heat, waste water recycling, etc., all of which affect the use of energy. In addition, “centralized” has lower installation, maintenance and control costs than “distributed”, and can also reduce peripheral equipment.

8. As for the cooling method, there are two kinds of air-cooled and water-cooled, air-cooled is not necessary to invest in additional cooling tower rain, but there must be good ventilation: water-cooled is the operation of the temperature is not affected by the environment, and is conducive to the life of the compressor, the only shortcomings of icing bursts and obstruction.

9. Power supply planning voltage requirements and the stability of the voltage drop must be required, centrifuges are usually high voltage, completely immobile, start-up will cause a shock to the power grid, should be kept in regular operation。

10. Maintenance room should have appropriate maintenance space and necessary lifting facilities and access channels, engineering staff and maintenance should also be given different maintenance professional training.

 

Selection Method

When you are ready to buy an air compressor, first of all, you should determine the working pressure needed at the air end, plus 1-2 bar margin, and then choose the pressure of the air compressor (the margin is to consider the pressure loss from the installation place of the air compressor to the actual distance of the air end piping, according to the length of the distance between the 1-2 bar appropriate consideration of the pressure margin). Of course, the size of the pipeline diameter and the number of turning points are also factors affecting the pressure loss, the larger the pipeline diameter and the fewer the turning points, the smaller the pressure loss; on the contrary, the greater the pressure loss.

 

Therefore, when the distance between the air compressor and the pipeline of each air end is too far, the diameter of the main pipeline should be enlarged appropriately. If the environmental conditions meet the installation requirements of the air compressor and the working conditions allow, it can be installed near the air end.

 

Volume Flow Rate Selection

1. In the selection of air compressor volumetric flow, should first understand the volume flow of all the air-using equipment, the total number of flows multiplied by 1.2 (that is, amplified by 20% margin);

2. New projects on the ground can be based on the flow rate value provided by the design institute for selection;

3. To the gas equipment suppliers to understand the volumetric flow parameters of the gas equipment for selection;

4. Air compressor station renovation can refer to the original parameter values combined with the actual gas situation for selection;

 

Appropriate selection, the user itself and the air compressor equipment are beneficial, selection of too large a waste, selection of too small may cause the air compressor long-term in the loading state or not enough gas or pressure can not play up and other disadvantages!

In the case of constant power, when the rotational speed changes, the volumetric flow rate and the working pressure change accordingly; for example: a 22KW air compressor, the working pressure is determined to be 7 bar at the time of manufacture, the rotational speed is calculated according to the technical curve of the compressor mainframe, and the exhaust volume is 3.8 m3/min; when the working pressure is determined to be 8 bar, the rotational speed must be lowered (otherwise, the drive motor will be overloaded), the At this point, the displacement is 3.6 m3/min; because, the speed is reduced, the displacement is also reduced accordingly, and so on.

 

The selection of power is to meet the conditions of working pressure and volumetric flow, the power supply capacity can meet the matching drive motor power can be used.

Therefore, the selection of air compressor steps are: first determine the working pressure, and then set the corresponding volume flow, and finally the power supply capacity.