Unconventional centrifugal bladeless turbine for low power range turboexpander applications

Abstract

Turboexpander generation technology is a promising solution for both CO2 emission reduction and providing autonomous auxiliary power for gas letdown stations and some technological processes. Nevertheless, its further development faces challenges to date due to several major restrictions: 1. long payback period of plants with conventional turbines; 2. significant annual fluctuations of gas inlet parameters; 3. high demands of conventional turbines for working fluid cleanliness. In order to address the abovementioned issues bladeless centrifugal reaction turbine may be introduced for turboexpander systems within power range up to 350 kWt. This turbine is a variation of so-called Segner wheel known for centuries. Its efficiency is lower comparing with the conventional rotary machines, but remains appropriate within the specific conditions of turboexpander application. Having proposed a conceptual design of a turbine the paper then highlights main features of its aerodynamics and kinematics. A comparison of the proposed turbine and axial transonic one is carried out within a wide range of pressure ratios as typical operating conditions. A centrifugal turbine advantage is highlighted which is an ability to generate comparable power as conventional ones while having lower cost and higher mud and erosion resistance.