Talking about the Modification and Selection of Air Compression Station
In the actual operation of the factory, it is often encountered that the rated gas production of the air compression station is quite different from the actual gas demand, the work load of the air compressor unit is low, and it is in a non-economic operation area, resulting in the operating efficiency of the air compression station Decline, resulting in waste of energy. In response to the above problems, factories usually carry out energy-saving transformations on air compression stations, by adjusting the number of air compressors, replacing air compressors with smaller rated displacements, etc., to make them work in high-efficiency areas as much as possible to achieve energy saving the goal of.
In the process of energy-saving transformation, to select the air compressor, first determine the total gas output of the air compression station. Since the air consumption on the user side is not completely constant, but fluctuates to a certain extent, how to determine a reasonable air consumption interval through the actual test operation data has become the first problem to be solved in the energy-saving transformation of the air compression station. If the air consumption interval is set too large, the air compressor is still running under a lower load, and energy is wasted; if the air consumption interval is set too small, the maximum air supply volume of the air compression station may not meet the production gas consumption Peak demand, which affects the normal production of the user terminal, is absolutely undesirable.
In my work, the author has made in-depth thinking about the problems encountered. From a statistical point of view, the operation data of the air compression station is analyzed, so as to determine a reasonable air consumption interval, which is the choice for energy-saving transformation of the air compression station. Type provides the basis. The following will illustrate through actual cases.
The air compression station of a solar cell factory is currently equipped with 3 centrifugal air compressors of exactly the same model. Each air compressor has a rated power of 500kW and a rated air output of 70m3/min. The operating data from February 15th to 24th, 2019 are shown in Table 1.
According to the operating data, the calculation shows that the average gas output of the air compression station is 138.56m3/min, the average maximum gas volume is 162.66m3/min, and the instantaneous maximum gas volume is 160.70m3/min.
Statistical knowledge tells us that standard deviation is a statistical indicator that reflects the degree of dispersion of a set of measured data. It refers to the range of fluctuations in the statistical results within a certain period of time. It is one of the important parameters of the normal distribution.
For a normal distribution, the probability that the variable falls within the interval (µ-1σ, µ+1σ) is 0.6827, the probability that the variable falls within the interval (µ-2σ, µ+2σ) is 0.9544, and the variable falls within the interval (µ-3σ). , Μ+3σ) The probability in the interval is 0.9974. In practical engineering applications, the average value of measured data can be used instead, and the standard deviation s can be used instead of σ.
standard deviation:
We calculated the operating data in Table 1, and found that the standard deviation of the average flow rate of the air compression station was s=9.60 m3/min (because the average flow rate calculated on the 24th was 107.66 m3/min, which is quite different from other figures, the calculation Eliminate when standard deviation). Therefore, the maximum gas output of an air compression station with a standard deviation of 2 times is selected as:
X+2S=138.56+2×9.60=157.76m³/min
The probability that the gas production volume is less than 157.56m3/min is 0.9544, and statistically, an event with a probability of less than 0.05 is considered a low probability event, so the choice is deemed reasonable.
Therefore, the air compression station can be modified as follows: keep the original two centrifugal air compressors unchanged, and its total gas output is 140m³/min. Considering that a certain margin is required in the actual process, Another centrifugal air compressor is replaced by an oil-free screw air compressor with a rated air output of 30m³/min, which can meet production needs.
