Analysis of factors affecting air compressor energy consumption

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The power consumption of centrifugal air compressors is related to factors such as exhaust volume, ambient temperature, pressure ratio, and efficiency. (1) As the ambient temperature decreases, power consumption also decreases. However, ambient temperature is a natural condition that is little affected by human factors and can essentially be regarded as a constant. (2) An increase in intake pressure results in reduced power consumption. The intake pressure is determined by the local atmospheric pressure and the resistance in the air compressor’s intake system (primarily the resistance of the filters). Therefore, using high-efficiency filters and regularly removing dust from them to keep the filter resistance within the designed range is also an important way to save energy in air compressors. (3) An increase in the mechanical efficiency of the air compressor leads to reduced power consumption. However, the mechanical efficiency of a compressor is primarily determined by its design, manufacturing, and installation; this parameter does not change much when the compressor is operating normally. (4) An increase in the isothermal efficiency of the air compressor leads to reduced power consumption. The isothermal efficiency of air compressors is closely related to operating conditions. Therefore, the key in operation is to ensure that the gas is adequately cooled in each stage of the coolers, so as to bring the compressor as close as possible to isothermal compression, effectively improving the compressor’s isothermal efficiency and reducing its power consumption. (5) If the exhaust volume of the air compressor decreases, power consumption also decreases. However, due to the limitations imposed by air separation production, it is not possible to make significant adjustments to the displacement under normal operating conditions ； To fully utilize the production potential of air separation, it is often necessary to have as large an air volume as possible to meet the requirements of air separation production. When there is an excess of air separation products and operation at reduced capacity is required, the guide vanes of the air compressor can also be adjusted to a smaller position in order to reduce the air flow and thus lower power consumption. However, due to the limitations of the \"choking region\", the amount of air that can be adjusted is limited ； Furthermore, when the guide vanes are closed, the suction resistance of the air compressor increases, which is also unfavorable for saving electricity. Therefore, adjusting the air volume is only one of the methods available for regulating air compressors, but it is not an effective way to save energy and reduce consumption. (6) If the exhaust pressure decreases, power consumption decreases. Theoretical calculations show that for air compressor units, with other parameters remaining constant, a reduction in the exhaust pressure of the compressor can lead to a decrease in its power consumption, resulting in significant energy savings. As indicated by the compressor’s performance curve, a lower exhaust pressure increases the volume of air discharged, thereby achieving both increased production and reduced energy use. The discharge pressure of the air compressor is determined by the pressure in the distillation column bottom and the resistance in the air system; therefore, while ensuring the normal operating pressure at the bottom of the column, optimizing the process to effectively reduce system resistance is an important way to save energy in air separation systems

Ensuring safe and stable production, reducing the frequency of startups and shutdowns, and maintaining the quality of oil, water, and air are the best ways to save energy and reduce consumption.

In my opinion, the points mentioned on the 3rd floor are quite comprehensive, but the most crucial factor is likely the design of the compressor, especially large-scale centrifugal compressors; for example, there is a significant difference in efficiency between foreign and domestic units

In fact, the energy consumption in air separation is directly related to the compressor selection, and indirectly related to the TSA and distillation towers. I won’t go into detail about the direct relationships; I’ll only briefly discuss the indirect ones. With proper design optimization of the TSA and distillation tower, the extraction efficiency is high; a high extraction efficiency implies a lower requirement for gas supply, which reduces the load on the compressor and thus saves energy consumption ； If the design of the TSA and the distillation tower is optimized properly, a lower pressure of compressed air is required; and with a lower pressure, energy savings are achieved. TSA employs new technologies such as the vertical radial flow TSA models from AL, LINDE, and AP, as well as the TPSA technology patented by AP; these enable a more balanced airflow distribution as air passes through the TSA, resulting in reduced pressure drop and thus energy savings. The distillation tower uses more precise and efficient packing and distributors to reduce the pressure drop, thereby improving the efficiency of the distillation process and the yield. This leads to a lower pressure drop, less gas consumption, and thus energy savings.