This type of vibration, especially when it appears and disappears with temp and pressure changes of the expander suction separator, is likely caused by seal and impeller shroud cross coupling. Because a cryogenic expander is two phase at the discharge, and typically two phase at the nozzle...
Depending on the application, using the discharge temperature to calculate the expander efficiency can be a poor method. For example, if the process stream at the discharge is two phase (which it usually is) then sometimes depending on the composition/temperature/pressure there can be a small...
I know of one application such as you describe using an ORC (organic rankine cycle) to generate power from wellhead water/steam return. The problem with this solution is that at such a low temperature the total efficiency will be very low (5% or so) and therefore the economics are not very good...
I'm not familiar with the equations that you posted, maybe the referenced paper was specific to a particular kind of bladed disc.
My experience is that the nodal diameters are calculated using modal analysis (FEA), then plotted versus the forcing function (nozzle/vanes and operating speed) via...
For note number 5, what you describe is called a compander. They are typically used when the motive force from the expander is not great enough to drive the compression stages, so an additional driver is used (steam turbine, gas turbine, electric motor). They are not very common, and the...
It is in your best interest to contact the vendor supplying the new turbo-expander and ask them for the recommended surge valve sizing. They will typically give you a maximum Cv for the surge valve which you can then double check against your own sizing. I imagine that you are going to want to...
The dimensionless parameter for the turbine impeller is specific speed, which has a certain range for optimal efficiency.
Assuming that the process can be scaled exactly (which it usually can since it is based on thermodynamics) then it is safe to assume that the inlet and outletr conditions...
There is not an exact pressure ratio that radial inflow turbines are limited to. Roughly speaking, I would say that 10:1 is near the maximum to maintain good efficiency, but there are also total enthalpy drop limitations that you may run into depending on the working fluid (as well as other...
Jbattershell, I agree that a test run on the proper MW gas at full power and full pressure is the most optimum test since it is the most complete test of everything already mentioned (aerodynamic forces on the rotor, etc).
Working for a centrifugal compressor OEM, we rarely test this way due...
It depends on where your tanker load of LNG comes from (geographically). In the older LNG plants (Indonesia), there is a higher concentration of C2+, in the newer plants (Qatar) they have significant upstream treating and the C2+ content is low. There are of coarse other sources besides these...
Inlet guide vanes add swirl to change the incidence angle at the inlet of the impeller. With a constant speed compressor, the velocity triangle at the inlet is a function of the tip speed at the eye and the gas velocity. The angle of the blade at the inlet (Beta) is designed to minimize...
The tolerances that you have are not excessive to the right machinist. In my experience, it depends what the machinist's background is. It is common for some parts to have extremely tight tolerances (I have worked with some high speed bearing applications in the 1-2 inch diameter bore range...
The AMB machinery that I am familiar with is all subcritical. Even in this type of machinery, the amplifiers can saturate trying to damp high order (4th, 5th, 6th) modes.
It seems like a supercritical rotor would be fairly difficult for AMB's to deal with.
