大容量遠心圧縮機の開発

Abstract

ターボ圧縮機は工場などで気体の昇圧や圧縮に用いられる多段式の遠心圧縮機である. その外形サイズを従来よりもコンパクトにできれば,圧縮機導入に関わるイニシャルコストを低減することができる. そのためには,多段圧縮機を構成する各段に対しては,より狭い空間で従来と同じ量の流体を処理できること,すなわち大容量化が求められる. しかし,より狭い空間に流体を無理に押し込むため,通過流速の増加や流れの急転向などによって,段効率の維持・改善は困難になる. また,流路断面積を拡大するために翼高さを高くしできるだけ翼を薄くしたいが,これらは翼部の応力増加や翼固有振動数の低下などにつながり得る. 本稿では,ギヤ内蔵型のターボ圧縮機への適用を目指して行った大容量圧縮機段の開発のなかで,上記の技術課題を克服するために行われた取組みについて紹介する.

A turbo-compressor is a type of multi-stage centrifugal compressor that is often used in factories to boost or compress gaseous fluids. By making its overall size more compact than ever before, it is possible to reduce the initial costs associated with the installation of a new compressor. In order to realize a more compact compressor, the same amount of fluid must be processed in a smaller space; that is, a higher flow capacity will be required for each of the constituent compressor stages. However, squeezing fluid forcibly into a smaller space will result in a higher through-flow velocity and/or a more acute flow turning, which inevitably makes it difficult to maintain or improve the stage efficiency. Moreover, raising the height or reducing the thickness of the blades for the purpose of widening the cross-section of the passage may result in an increase in blade stress and/ or a reduction in the blade’s natural frequency. This report describes the efforts made to overcome the above-mentioned technical challenges that occurred in the development of a high-flow compressor stage that is intended to be applied in integrally geared turbo-compressors.