Inlet and outlet pressures of a compressor at a constant rotational speed
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1. For a centrifugal compressor with a constant rotational speed, what are the common reasons for an increase in its power? As the inlet pressure increases, how does the outlet pressure change at a constant rotational speed?
1 For a compressor with a fixed structure and a determined rotational speed, power is a parameter that can be determined; it represents a result. 2 Typical causes include changes in the properties of the medium, such as temperature changes that affect the density of gaseous media, phase changes within the medium (such as the presence of liquid phases in a gas phase), changes in the characteristics of the medium, and mechanical defects. 3 For compressors, the energy input is indirectly reflected through the pressure ratio; an increase in inlet and outlet pressures means that, at a constant rotational speed, the outlet pressure also increases. But it is limited by power and the mechanical strength of the housing.
At a constant rotational speed, changes in the temperature of the medium, the outlet pressure, or the molecular weight or composition of the medium lead to changes in power. :)
Rotational speed must be relative only. Compressors are generally driven by steam turbines. The speed of the turbine does not change with the load; only the amount of steam used changes. An increase in power indicates an increase in load or changes in the process parameters of the medium.
As the inlet pressure increases, the outlet pressure also rises at a constant rotational speed.
For a centrifugal compressor with a constant rotational speed, the power is related to factors such as the composition of the medium, the compression ratio of the compressor, and its efficiency； If the inlet pressure increases, the outlet pressure also increases at a constant rotational speed.
For centrifugal compressors, the compression ratio of the compressor is fixed. When the pressure at the inlet increases, the pressure at the outlet also increases accordingly.
Why does an increase in inlet pressure lead to an increase in outlet pressure for a compressor with a constant rotational speed? As the inlet pressure increases, the density of the inlet gas rises, which in turn leads to an increase in the volume of gas entering the compressor. For a compressor with a constant rotational speed, the work done by the rotor should remain unchanged; therefore, the pressure of the gas exiting the compressor should decrease, right? I’m not sure if what I said is correct; I’m quite confused now. Please help analyze it for me
For a thorough understanding of the variable-load operation of compressors, please refer to the book \"Process Design Data for Refining Equipment_Compressor Process Calculations\", which provides detailed explanations on this topic.