I was thinking this might be a vapour expander however this sounds like a liquid expander where the process fluid is also the lubricant. Unfortunately I am not familiar with this design. It makes sense that lower flow will result in lower expander power to the generator, however it seems...
Is there any update to this? Is it correct that the lube oil system or bearing feed ports for the expander were not designed correctly? Is this an APCI expander?