Objectives and problems to be solved:
Industrial centrifugal compressors are used in a very wide range of oil and gas applications. Compressor efficiency has always been a major issue as well as compressor cost and reliability, but recently the availability of new computational tools and optimisation techniques has raised a lot the attention on very high efficiency machines. Furthermore, the introduction of new processes (like LNG-Liquefied Natural Gas) where the centrifugal compressor plays a critical role for the whole plant efficiency makes the need of a high efficiency design even more important to stay on the market. The main objective of this project is to provide a solution to the above listed items. High efficiency stages are divided in "large flow" and "low flow": for the first the efficiency gain is mainly obtained with a very accurate aero-thermo design of the impeller from fluid dynamic point of view, for the second the attention is focused on the leakage which impacts severely on compressor performance.
Description of the work:
The proposed work is divided into two different streams: impeller design and seal design. For both activities the application of automatic algorithms for optimum solution search are applied.
The activity will proceed through all the logical actions which are needed for a new design development:
· Impeller and seals specs identification
· Design tools and optimisation algorithms links creation
· New designs development
· Tests to validate the new design.
Expected Results and Exploitation Plans:
The final expected result is the creation of an advanced design system which can be used friendly from any designer to get an optimum design in a time comparable to the actual procedure (fully manual). Furthermore, it is expected that using this new automatic design system an efficiency gain of 6 - 7 % could be available with respect to the actual design without any decay in operating range, stability and reliability of the machine. This, if achieved, will represent a sudden step in the industrial centrifugal compressor technology.
Concerning the aerodynamic optimisation the fluid dynamic solver has been successively coupled to the optimisation algorithm. The whole program has been tested on a 2D impeller producing very good results (2% increase in efficiency) with a reasonable CPU time. Moreover, even from an industrial point of view, the results obtained can be considered very good because the time required is quite low and so the use of the program can be easily introduced in the engineering process to design a centrifugal compressor. An advanced procedure for blade machining has been implemented to realise impellers starting from a CAD program. This procedure can be easily used to produce the impeller starting from the parameters data set specified by the optimisation algorithm. A new sealing system satisfying the initial specifications given by NP was designed.
Funding SchemeCSC - Cost-sharing contracts