1, compressed air use.
2, the minimum use of pressure.
3, the tip and the peak of the demand for air. If the highest and lowest use pressure difference of up to 3bar, it is necessary to consider the "high and low pressure shunt", and then according to the tip of the peak, away from the burden of change to choose a different type of air compressor, such as the "base load" using centrifugal (single & gt; 75CMM) or Spiral (single 4, according to different quality of gas selection and configuration of different forms and grades of dryers and precision filters, too good quality waste of energy, insufficient quality to affect the process, must be carefully considered.
5, the air compressor control technology is rapidly changing, "multi-machine chain", "variable frequency variable speed" and "remote monitoring" and other technologies, can effectively inhibit the centrifugal BOV The technology of "multi-machine chain", "frequency conversion" and "remote monitoring" can effectively inhibit the waste of centrifugal BOV and spiral empty car (saving 25-40% of electricity cost), reduce the spare capacity and investment (15-30%), and stabilize the pressure of gas supply (plus or minus 0.1 bar).
6, the operating efficiency can not only compare the catalog on the nominal horsepower and air volume, the focus is on the actual "performance curve" and "air volume per horse.
7, the installation considers the size of the room space, ventilation conditions, noise insulation, waste heat, waste water recycling, etc. are affected by the use of energy. In addition, "centralized" than "distributed" has a lower cost of installation, maintenance and control, can also reduce peripheral equipment.
8, as for the cooling method of air-cooled and water-cooled two kinds of 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, the life of the compressor in favor of the only shortcomings of icing and blockage of the burst.
9, power supply planning voltage requirements and the stability of the voltage drop must be required, centrifuges are usually high voltage, can not move at all, the start of the grid will cause an impact, should be kept in regular operation.
10, maintenance room to have appropriate maintenance space and the necessary lifting facilities and access to the channel, engineering staff and maintenance should also be given different maintenance of professional training.
Second, the air compressor purchase method:
Preparing to buy air compressor, first of all, to determine the air end of the required working pressure, plus 1-2bar margin, and then select the pressure of the air compressor, (the margin is to consider the air compressor installation location to the actual air end of the pipeline distance pressure loss, according to the length of the distance between 1-2bar appropriate consideration of the pressure margin). (This margin is to consider the pressure loss from the air compressor installation location to the actual air-using end. 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 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.
Three, air compressor volumetric flow selection
1, in the selection of air compressor volumetric flow, you should first understand the volumetric flow of all the air-using equipment, the total number of flow multiplied by 1.2 (i.e., enlargement of the margin of 20%);
2, the new project can be based on the flow rate of the design institute provided by the selection of the value of the flow rate;
3, to the air equipment suppliers to understand the parameters of the volumetric flow of the equipment. Gas equipment volume flow parameters for selection;
4, air compressor station renovation can refer to the original parameter values combined with the actual use of gas selection;
The appropriate selection of the user itself and the air compressor equipment are beneficial, selection of too large a waste of selection is too small may result in the compressor in a long-term loading state or the use of gas is not enough or the pressure does not play on the drawbacks.
The relationship between the three:
In the case of power is unchanged, when the rotational speed changes, the volumetric flow and working pressure changes accordingly; for example: a 22KW air compressor, in the manufacture of working pressure is determined to be 7bar, according to the compressor technical curve of the main engine to calculate the rotational speed, the exhaust volume of 3.8m3/min; when determining the working pressure of 8bar, the rotational speed must be reduced (otherwise the drive electric pressure). When the working pressure is determined to be 8bar, the rotational speed must be reduced (otherwise the drive motor will be overloaded), at this time, the exhaust volume is 3.6m3/min; because, the rotational speed is reduced, the exhaust is also reduced accordingly, and so on.
Power selection is to meet the working pressure and volume flow conditions, power supply capacity to meet the matching drive motor power can be used.
So, 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.
Four, air compressor selection criteria
1, pressure parameter matching
Working air pressure control: that is, when the work of the air pressure is required to be how big. Most of the air compressor for laboratory air pressure in 0-8BAR (about 0-8 kg) adjustable, in line with the air pressure requirements of the experimental equipment.
Stable and continuous exhaust volume (usually expressed in L/MIN): it refers to how many liters of gas flow per minute in the case of rated working pressure, and to ensure continuous and stable gas flow, so the working stability of the air compressor is very high requirements.
2, compressed air quality
Oil-free air compressor is the first choice: oil-free air compressor machine itself does not contain oily materials, work without adding any lubricant, so greatly improve the quality of the discharged air, the user to support the safety of the equipment is also guaranteed, unlike the oil compressor, due to the discharged gas contains a large number of oil molecules, will be on the user's equipment to bring different degrees of corrosion. Unlike the oiled air compressor, the discharge gas contains a large number of oil molecules, which will bring different degrees of corrosion to the user's equipment, so it is necessary to choose the oil-free silent air compressor to ensure the quality of air. After configuring the air filtration device, the air quality should reach the following international standard values.
The selection of air compressor is mainly based on the working pressure and flow rate of pneumatic system.
The working pressure of the air source should be about 20% higher than the highest working pressure in the pneumatic system, because the along-travel loss and local loss of the air supply pipeline should be considered. If the working pressure requirement is lower in some parts of the system, a pressure reducing valve can be used to supply air. The rated exhaust pressure of air compressor is categorized into low pressure (0.7~1.0MPa), medium pressure (1.0~10MPa), high pressure (10~100MPa) and ultra-high pressure (over 100MPa). Commonly used pressure is generally 0.7-1.25. First of all, choose the type of air compressor according to the characteristics of air compressor requirements.
And then according to the two parameters of working pressure and flow rate required by the pneumatic system, determine the output pressure pc and suction flow rate qc of the air compressor, and finally select the model of the air compressor.