JP2011021503A - Suction casing of centrifugal compressor and design method of suction casing of centrifugal compressor - Google Patents

Suction casing of centrifugal compressor and design method of suction casing of centrifugal compressor Download PDF

Info

Publication number
JP2011021503A
JP2011021503A JP2009165410A JP2009165410A JP2011021503A JP 2011021503 A JP2011021503 A JP 2011021503A JP 2009165410 A JP2009165410 A JP 2009165410A JP 2009165410 A JP2009165410 A JP 2009165410A JP 2011021503 A JP2011021503 A JP 2011021503A
Authority
JP
Japan
Prior art keywords
suction casing
suction
casing
centrifugal compressor
flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2009165410A
Other languages
Japanese (ja)
Other versions
JP5263043B2 (en
Inventor
Manabu Yagi
学 八木
Takanori Shibata
貴範 柴田
Toshio Ito
俊雄 伊藤
Hideo Nishida
秀夫 西田
Hiromi Kobayashi
博美 小林
Masanori Tanaka
征将 田中
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Plant Technologies Ltd
Original Assignee
Hitachi Plant Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Plant Technologies Ltd filed Critical Hitachi Plant Technologies Ltd
Priority to JP2009165410A priority Critical patent/JP5263043B2/en
Publication of JP2011021503A publication Critical patent/JP2011021503A/en
Application granted granted Critical
Publication of JP5263043B2 publication Critical patent/JP5263043B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/4206—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
    • F04D29/4213—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps suction ports

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suction casing of a centrifugal compressor with suppressed deterioration in efficiency of the centrifugal compressor by effectively reducing a pressure loss occurring upon uniformizing suction flow of air flow flowing into the suction casing. <P>SOLUTION: This suction casing of the centrifugal compressor is formed so that a ratio A1/As of a flow passage cross sectional area A1 at a merging part of a suction nozzle 32 of the suction casing 3 and an annular flow passage 33 formed inside the suction casing 3, and a minimum flow passage cross sectional area As between an axial flow passage 34 formed inside the suction casing 3 and a centrifugal impeller 2 becomes 2.5 or more, and the flow passage shape of the suction casing 3 is configured so that a ratio A2/As of a cylindrical surface area A2 obtained from a product of an annular flow passage radius r2 of the annular flow passage 33 formed inside the suction casing 3 and an axial flow passage dimension b1, and the minimum flow passage cross sectional area As, becomes 12 or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は作動流体を圧縮する遠心圧縮機の吸込ケーシング及び遠心圧縮機の吸込ケーシングの設計方法に関する。   The present invention relates to a suction casing of a centrifugal compressor that compresses a working fluid and a method for designing a suction casing of a centrifugal compressor.

作動流体を圧縮する遠心圧縮機として、例えば非特許文献の「EXPERIMENTAL AND COMPUTATIONAL STUDY OF A RADIAL COMPRESSOR INLET」(ASME Paper 95-GT-82、1995年、P.7)に遠心圧縮機の吸込ケーシングに関する技術が開示されている。   As a centrifugal compressor that compresses the working fluid, for example, a non-patent document `` EXPERIMENTAL AND COMPUTATIONAL STUDY OF A RADIAL COMPRESSOR INLET '' (ASME Paper 95-GT-82, 1995, p. 7) relates to the suction casing of the centrifugal compressor. Technology is disclosed.

ところで、この遠心圧縮機の吸込ケーシングでは、遠心圧縮機の性能を損なわないようにするために、軸方向吸込型の遠心圧縮機のインペラに流入する気流を周方向に均一化する必要がある。   By the way, in the suction casing of this centrifugal compressor, in order not to impair the performance of the centrifugal compressor, it is necessary to make the airflow flowing into the impeller of the axial suction type centrifugal compressor uniform in the circumferential direction.

そのための手段として、特開平１０−３１８１９１号公報には、遠心圧縮機の吸込ケーシング内部に吸込口から吸い込まれる気流を分割するガイド板を該吸込ケーシング内部の入口部分に設けた技術が開示されている。   As a means for this, Japanese Patent Application Laid-Open No. 10-318191 discloses a technique in which a guide plate that divides an airflow sucked from a suction port into a suction casing of a centrifugal compressor is provided at an inlet portion inside the suction casing. Yes.

また、特開２００６−２００４８９号公報には、遠心圧縮機の吸込ケーシング内部に回転軸と同心状に円弧状のガイドフェンスを設けた技術が開示されている。   Japanese Patent Application Laid-Open No. 2006-200209 discloses a technique in which an arcuate guide fence is provided concentrically with a rotating shaft inside a suction casing of a centrifugal compressor.

特開平１０−３１８１９１号公報Japanese Patent Laid-Open No. 10-318191 特開２００６−２００４８９号公報Japanese Patent Laid-Open No. 2006-200489

「EXPERIMENTAL AND COMPUTATIONAL STUDY OF A RADIAL COMPRESSOR INLET」、（ASME Paper95-GT-82、1995年、P.7）"EXPERIMENTAL AND COMPUTATIONAL STUDY OF A RADIAL COMPRESSOR INLET", (ASME Paper95-GT-82, 1995, P.7)

特許文献１に記載の遠心圧縮機の吸込ケーシングでは、吸込ケーシング内部の入口部分にガイド板を設けて吸込口から吸い込まれる気流を分割して吸込ケーシングの内部の羽根車に流入する流れを周方向に均一化させている。   In the suction casing of the centrifugal compressor described in Patent Document 1, a guide plate is provided at the inlet portion inside the suction casing to divide the airflow sucked from the suction port and flow the flow flowing into the impeller inside the suction casing in the circumferential direction. It is made uniform.

しかしながら、吸込ケーシング内部の入口部分にガイド板を設けることによって吸込ケーシングでの圧力損失が増加し、遠心圧縮機の効率低下を招くことになる。また、ガイド板については、ガイド板の取付け位置や方向、長さなどの複数の設計パラメータを要するが、最適なガイド板形状を得るには長年に亘る経験や多数の実験が必要となる。   However, providing a guide plate at the inlet portion inside the suction casing increases the pressure loss in the suction casing, leading to a reduction in efficiency of the centrifugal compressor. In addition, the guide plate requires a plurality of design parameters such as the mounting position, direction, and length of the guide plate. To obtain an optimal guide plate shape, many years of experience and many experiments are required.

特許文献２に記載の遠心圧縮機の吸込ケーシングでは、吸込ケーシング内部に遠心圧縮機の回転軸と同心状に円弧状のガイドフェンスを設けて流れを周方向に均一化させて、羽根車への流入速度分布を均一化でき圧縮機の効率が向上する。   In the suction casing of the centrifugal compressor described in Patent Document 2, an arc-shaped guide fence is provided concentrically with the rotary shaft of the centrifugal compressor in the suction casing to make the flow uniform in the circumferential direction, and to the impeller. The inflow velocity distribution can be made uniform, and the efficiency of the compressor is improved.

しかしながら、ガイドフェンスを設けたことによる吸込ケーシングの圧力損失増加によって遠心圧縮機の効率低下を招くことについては何等考慮されていない。また、ガイドフェンスについても、ガイドフェンスの取付け位置や方向、長さなどの複数の設計パラメータを要し、最適なガイドフェンス形状を得るには長年に亘る経験や多数の実験が必要となる。   However, no consideration is given to reducing the efficiency of the centrifugal compressor due to an increase in the pressure loss of the suction casing due to the provision of the guide fence. Also, the guide fence requires a plurality of design parameters such as the installation position, direction, and length of the guide fence. To obtain an optimal guide fence shape, many years of experience and many experiments are required.

また、非特許文献１に記載の遠心圧縮機の吸込ケーシングでは、吸込ケーシング内部に周方向に４５°間隔で半径方向に放射状に広がるガイドベーンを８枚設けて流れを周方向に均一化させている。しかしながら、ガイドベーンを設けることによって吸込ケーシングの圧力損失が増加し、遠心圧縮機の効率低下を招くことになる。   Further, in the suction casing of the centrifugal compressor described in Non-Patent Document 1, eight guide vanes radially extending at 45 ° intervals in the circumferential direction are provided inside the suction casing to make the flow uniform in the circumferential direction. Yes. However, the provision of guide vanes increases the pressure loss of the suction casing, leading to a reduction in the efficiency of the centrifugal compressor.

本発明の目的は、吸込ケーシング内部に気流の圧力損失を生じる整流部材を設置せずに、遠心圧縮機の吸込ケーシングに流入する気流の吸込流れの均一化を可能にして遠心圧縮機の効率低下を抑制した遠心圧縮機の吸込ケーシング、及び遠心圧縮機の吸込ケーシングの設計方法を提供することにある。   The object of the present invention is to reduce the efficiency of the centrifugal compressor by enabling the uniform suction flow of the airflow flowing into the suction casing of the centrifugal compressor without installing a rectifying member that causes a pressure loss of the airflow inside the suction casing. An object of the present invention is to provide a suction casing for a centrifugal compressor and a method for designing a suction casing for the centrifugal compressor.

本発明である遠心圧縮機の吸込ケーシングは、回転軸及びこの回転軸の外周に設置されて気流を圧縮する遠心羽根車を内部にそれぞれ収容する羽根車ケーシングと、前記羽根車ケーシングの上流側に設置されており、遠心羽根車の回転軸に対して直交する方向に開口した吸込口から回転軸に対して直交する内向き方向に気流を導く吸込ノズルを備え、この吸込ノズルから流入した回転軸に対して半径方向の流れを全周に広げる環状流路と、この環状流路で導かれた半径方向からの流れを回転軸中心方向に集約するとともに、半径方向から回転軸方向へ流れの向きを転向して気流を遠心羽根車へ導く軸方向流路をその内部に形成した吸込ケーシングから構成される遠心圧縮機の吸込ケーシングにおいて、前記吸込ケーシングの吸込ノズルと該吸込ケーシングの内部に形成された環状流路の合流部における流路断面積Ａ１と吸込ケーシングの内部に形成された軸方向流路と遠心羽根車の間における最小流路断面積Ａｓの比Ａ１／Ａｓが２．５以上になるように形成すると共に、前記吸込ケーシングの内部に形成された環状流路の環状流路半径と軸方向流路幅の積から求まる円筒表面積Ａ２と前記最小流路断面積Ａｓの比Ａ２／Ａｓが１２以上になるように前記吸込ケーシングの流路形状を形成したことを特徴とする。   The suction casing of the centrifugal compressor according to the present invention includes an impeller casing that accommodates a rotating shaft and a centrifugal impeller that is installed on the outer periphery of the rotating shaft and compresses an airflow, and an upstream side of the impeller casing. A rotation shaft that is installed and has a suction nozzle that guides airflow in an inward direction perpendicular to the rotation axis from a suction port that opens in a direction orthogonal to the rotation axis of the centrifugal impeller, and the rotation shaft that has flowed from the suction nozzle An annular flow channel that spreads the flow in the radial direction over the entire circumference, and the flow from the radial direction guided by this annular flow channel is concentrated in the central direction of the rotation axis and the direction of flow from the radial direction to the rotation axis direction In the suction casing of the centrifugal compressor, the suction nozzle of the suction casing, and the suction nozzle. Ratio A1 / As of the flow path cross-sectional area A1 at the junction of the annular flow paths formed inside the casing and the minimum flow path cross-sectional area As between the axial flow path formed inside the suction casing and the centrifugal impeller The cylindrical surface area A2 obtained from the product of the annular channel radius and the axial channel width of the annular channel formed inside the suction casing and the minimum channel cross-sectional area The flow path shape of the suction casing is formed so that the As ratio A2 / As is 12 or more.

また本発明である遠心圧縮機の吸込ケーシングの設計方法は、回転軸及びこの回転軸の外周に設置されて気流を圧縮する遠心羽根車を内部にそれぞれ収容する羽根車ケーシングと、前記羽根車ケーシングの上流側に設置されており、遠心羽根車の回転軸に対して直交する方向に開口した吸込口から回転軸に対して直交する内向き方向に気流を導く吸込ノズルを備え、この吸込ノズルから流入した回転軸に対して半径方向の流れを全周に広げる環状流路と、この環状流路で導かれた半径方向からの流れを回転軸中心方向に集約するとともに、半径方向から回転軸方向へ流れの向きを転向して気流を遠心羽根車へ導く軸方向流路をその内部に形成した吸込ケーシングから構成される遠心圧縮機の吸込ケーシングの設計方法において、前記吸込ケーシングの吸込ノズルと該吸込ケーシングの内部に形成された環状流路の合流部における流路断面積Ａ１と吸込ケーシングの内部に形成された軸方向流路と遠心羽根車の間における最小流路断面積Ａｓの比Ａ１／Ａｓと、流れを表す物理量の周方向分布を評価するパラメータとの相関グラフを参照して所望の値になるように設定すると共に、前記吸込ケーシングの内部に形成された環状流路の環状流路半径と軸方向流路幅の積から求まる円筒表面積Ａ２と前記最小流路断面積Ａｓの比Ａ２／Ａｓと、流れを表す物理量の周方向分布を評価するパラメータとの相関グラフを参照して所望の値になるように設定して前記吸込ケーシングの吸込ノズルと前記環状流路の合流部における流路断面形状および前記環状流路の環状流路半径を決定することを特徴とする。   Further, the method for designing a suction casing of a centrifugal compressor according to the present invention includes an impeller casing for accommodating therein a rotating shaft and a centrifugal impeller that is installed on the outer periphery of the rotating shaft and compresses an airflow, and the impeller casing. A suction nozzle that guides the airflow in an inward direction perpendicular to the rotation axis from a suction port that opens in a direction perpendicular to the rotation axis of the centrifugal impeller, and from this suction nozzle An annular flow channel that spreads the flow in the radial direction around the rotation axis that flows in, and the flow from the radial direction guided by the annular flow channel in the central direction of the rotation axis, and from the radial direction to the rotation axis direction In the method of designing a suction casing of a centrifugal compressor, the suction case is composed of a suction casing having an axial flow passage formed therein for turning the flow direction to the centrifugal impeller. Flow path cross-sectional area A1 at the junction of the annular suction channel and the annular flow channel formed inside the suction casing, and the minimum flow channel breakage between the axial flow channel formed inside the suction casing and the centrifugal impeller A ratio A1 / As of the area As and a correlation graph between the parameters for evaluating the circumferential distribution of the physical quantity representing the flow are set so as to have a desired value, and an annular formed inside the suction casing. Correlation between the cylindrical surface area A2 obtained from the product of the annular channel radius and the axial channel width of the channel and the ratio A2 / As of the minimum channel cross-sectional area As and the parameter for evaluating the circumferential distribution of the physical quantity representing the flow Determine the flow path cross-sectional shape at the junction of the suction nozzle of the suction casing and the annular flow path and the annular flow path radius of the annular flow path by setting the desired value with reference to the graph And butterflies.

本発明によれば、吸込ケーシング内部に気流の圧力損失を生じる整流部材を設置せずに、遠心圧縮機の吸込ケーシングに流入する気流の吸込流れの均一化を可能にして遠心圧縮機の効率低下を抑制した遠心圧縮機の吸込ケーシング、及び遠心圧縮機の吸込ケーシングの設計方法が実現できる。   According to the present invention, it is possible to make the suction flow of the airflow flowing into the suction casing of the centrifugal compressor uniform without reducing the efficiency of the centrifugal compressor without installing a rectifying member that causes a pressure loss of the airflow inside the suction casing. The suction casing of the centrifugal compressor and the suction casing design method of the centrifugal compressor can be realized.

本発明の第１実施例である吸込ケーシングを備えた多段遠心圧縮機の構造を示した断面図。Sectional drawing which showed the structure of the multistage centrifugal compressor provided with the suction casing which is 1st Example of this invention. 図１に示した第１実施例の吸込ケーシングを備えた多段遠心圧縮機におけるＡ−Ａ断面図。The AA sectional view in the multistage centrifugal compressor provided with the suction casing of the 1st example shown in FIG. 本発明の各実施例の多段遠心圧縮機における吸込ノズルと環状流路の合流部における流路断面積Ａ１と、軸方向流路と遠心羽根車の間における最小流路断面積Ａｓの比Ａ１／Ａｓに対する初段羽根車入口流速偏差ΔＣを示すグラフ。Ratio A1 / of the flow path cross-sectional area A1 at the junction of the suction nozzle and the annular flow path in the multistage centrifugal compressor of each embodiment of the present invention and the minimum flow path cross-sectional area As between the axial flow path and the centrifugal impeller The graph which shows the first stage impeller entrance flow velocity deviation (DELTA) C with respect to As. 本発明の各実施例の多段遠心圧縮機における環状流路の環状流路半径と軸方向流路幅の積から求まる円筒表面積Ａ２と、軸方向流路と遠心羽根車の間における最小流路断面積Ａｓの比Ａ２／Ａｓに対する初段羽根車入口流速偏差ΔＣを示すグラフ。In the multistage centrifugal compressor of each embodiment of the present invention, the cylindrical surface area A2 obtained from the product of the annular channel radius and the axial channel width of the annular channel, and the minimum channel breakage between the axial channel and the centrifugal impeller The graph which shows the first stage impeller entrance flow velocity deviation (DELTA) C with respect to ratio A2 / As of area As. 本発明の第１実施例である多段遠心圧縮機における環状流路の環状流路半径の２倍と合流部の流路断面積の幅方向寸法との比Ａ２×ｒ２／ａ１に対する初段羽根車入口流速偏差ΔＣを示すグラフ。First stage impeller inlet with respect to a ratio A2 × r2 / a1 of twice the annular channel radius of the annular channel and the width direction dimension of the channel cross-sectional area of the confluence in the multistage centrifugal compressor according to the first embodiment of the present invention The graph which shows flow-velocity deviation (DELTA) C. 本発明の第２実施例である多段遠心圧縮機に備えられた吸込ケーシングにおける、図１のＡ−Ａ断面に相当する断面図。Sectional drawing equivalent to the AA cross section of FIG. 1 in the suction casing with which the multistage centrifugal compressor which is 2nd Example of this invention was equipped.

次に本発明の実施例である遠心圧縮機の吸込ケーシング及び遠心圧縮機の吸込ケーシングの設計方法について、図１〜図５を参照して以下に詳細に説明する。なお、本実施例の遠心圧縮機は多段遠心圧縮機の吸込ケーシングを例にとり説明するが、単段の場合や、類似構造を有するその他の遠心圧縮機にも本発明は適用可能である。   Next, the design method of the suction casing of the centrifugal compressor and the suction casing of the centrifugal compressor according to the embodiment of the present invention will be described in detail with reference to FIGS. In addition, although the centrifugal compressor of a present Example demonstrates taking the case of the suction casing of a multistage centrifugal compressor, this invention is applicable also to the case of a single stage and the other centrifugal compressor which has a similar structure.

図１は、本発明の第１実施例に係る吸込ケーシングを備えた多段遠心圧縮機の構造を示した断面図であり、図２は、図１におけるＡ−Ａ断面図であり、多段遠心圧縮機に備えられた吸込ケーシングの横断面の形状を示している。   FIG. 1 is a cross-sectional view showing a structure of a multistage centrifugal compressor including a suction casing according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. The shape of the cross section of the suction casing with which the machine was equipped is shown.

図１及び図２に示すように、本発明の第１実施例の吸込ケーシングを備えた遠心圧縮機である多段遠心圧縮機１００では、１本の回転軸１と、この回転軸１の外周に取付けられ該回転軸１の軸方向に離間して配設された複数の遠心羽根車２が羽根車ケーシング４の内部に回転可能に設置され、更に羽根車ケーシング４の内部には前記遠心羽根車２を相互に連絡して該遠心羽根車２によって圧縮された作動流体１０を流下させる内部流路７が形成されている。   As shown in FIGS. 1 and 2, in a multistage centrifugal compressor 100 that is a centrifugal compressor provided with a suction casing of the first embodiment of the present invention, one rotary shaft 1 and an outer periphery of the rotary shaft 1 are provided. A plurality of centrifugal impellers 2 mounted and spaced apart in the axial direction of the rotary shaft 1 are rotatably installed inside the impeller casing 4, and further inside the impeller casing 4 the centrifugal impeller An internal flow path 7 is formed through which the working fluid 10 compressed by the centrifugal impeller 2 flows down.

そして、回転軸１及び遠心羽根車２を内部に収容する前記羽根車ケーシング４は、その上流側を、吸い込んだ気流を作動流体１０として導く吸込ケーシング３に接続されており、この吸込ケーシング３から導入した作動流体１０を該羽根車ケーシング４の内部に設置した遠心羽根車２の回転によって圧縮し、昇圧した作動流体１０を外部に吐出する吐出スクロール５をその下流側に設けている。   The impeller casing 4 that houses the rotary shaft 1 and the centrifugal impeller 2 is connected to the suction casing 3 that guides the sucked airflow as the working fluid 10 on the upstream side thereof. A discharge scroll 5 that compresses the introduced working fluid 10 by the rotation of the centrifugal impeller 2 installed inside the impeller casing 4 and discharges the pressurized working fluid 10 to the outside is provided on the downstream side.

なお、吸込ケーシング３は、図１および図２に示すように、吸込ケーシング３の入口側で作動流体１０となる気流を該吸込ケーシング３に導入する吸込口３１と、吸込口３１から導入した気流を遠心羽根車２側に導く流路断面積が上流側から下流側に行くほど暫減する吸込ノズル３２とを備えており、この吸込ケーシング３の吸込ノズル３２を通じて導入された作動流体１０となる気流は、吸込ケーシング３の内部に形成された環状流路３３に流入した後に、この環状流路３３に連通した軸方向流路３４を流下して羽根車ケーシング４の内部に配設した複数の遠心羽根車２に導かれ、これらの複数の遠心羽根車２の回転によって順次、圧縮される。   As shown in FIGS. 1 and 2, the suction casing 3 includes a suction port 31 that introduces an airflow that becomes the working fluid 10 on the inlet side of the suction casing 3 into the suction casing 3, and an airflow that is introduced from the suction port 31. And a suction nozzle 32 that gradually decreases from the upstream side toward the downstream side, and the working fluid 10 introduced through the suction nozzle 32 of the suction casing 3 is provided. The airflow flows into an annular flow path 33 formed inside the suction casing 3, and then flows down an axial flow path 34 communicating with the annular flow path 33 to be disposed inside the impeller casing 4. It is guided to the centrifugal impeller 2 and is sequentially compressed by the rotation of the plurality of centrifugal impellers 2.

遠心圧縮機の外部より吸込口３１から吸込ケーシング３の内側に吸入された作動流体１０は、図２に示したように、吸込ケーシング３の内側の吸込ノズル３２を遠心羽根車２の回転軸１に対して直交する内向き方向に流れて吸込ケーシング３の内部に形成された環状流路３３に至る。   The working fluid 10 sucked into the suction casing 3 from the suction port 31 from the outside of the centrifugal compressor moves the suction nozzle 32 inside the suction casing 3 through the rotary shaft 1 of the centrifugal impeller 2 as shown in FIG. Flows in an inward direction orthogonal to the annular flow path 33 formed inside the suction casing 3.

吸込ケーシング３の内側の吸込ノズル３２から流出する回転軸１に対して半径方向内向きの作動流体１０の流れは、この環状流路３３によって環状流路３３の全周に広げられ、この環状流路３３の全周から軸方向流路３４に半径方向内向きに流入する。   The flow of the working fluid 10 inward in the radial direction with respect to the rotary shaft 1 flowing out from the suction nozzle 32 inside the suction casing 3 is spread over the entire circumference of the annular flow path 33 by the annular flow path 33. It flows inward in the radial direction into the axial flow path 34 from the entire circumference of the path 33.

環状流路３３から半径方向内向きに軸方向流路３４に流入した作動流体１０は、回転軸１の中心方向に集約されるとともに、その流れ方向を半径方向から回転軸方向へ転向されて羽根車ケーシング４の内部に配設された多段の遠心羽根車２へ流入する。   The working fluid 10 that has flowed into the axial flow path 34 inward in the radial direction from the annular flow path 33 is concentrated in the central direction of the rotary shaft 1, and the flow direction is changed from the radial direction to the rotary shaft direction to impeller blades. It flows into the multistage centrifugal impeller 2 disposed inside the car casing 4.

本実施例の遠心圧縮機における羽根車ケーシング４の内部に配設された遠心羽根車２は、軸方向吸込を想定して設計されているので、作動流体１０が周方向に均一、かつ軸方向に並行して遠心羽根車２へ流入するほど遠心圧縮機１００の効率は向上する。   Since the centrifugal impeller 2 disposed inside the impeller casing 4 in the centrifugal compressor of this embodiment is designed assuming axial suction, the working fluid 10 is uniform in the circumferential direction and axial. In parallel, the efficiency of the centrifugal compressor 100 is improved as it flows into the centrifugal impeller 2.

本実施例の遠心圧縮機の吸込ケーシング３は、作動流体１０を円周方向に均一、かつ軸方向に並行して遠心羽根車２へ流入させるために、吸込ケーシング３の吸込ノズル３２と吸込ケーシング３の内部に形成された環状流路３３の合流部における長方形の流路断面積Ａ１（＝ａ１×ｂ１）と、吸込ケーシング３の内部の軸方向流路３４と遠心羽根車２との間で形成される最小流路断面積Ａｓ（＝π×（ｒｓｈ ２−ｒｈ ２））との比Ａ１／Ａｓの値が、後述する図３に示すように、２．５以上となるように設定している。 The suction casing 3 of the centrifugal compressor of the present embodiment is configured so that the working fluid 10 is made to flow into the centrifugal impeller 2 in the circumferential direction and in parallel to the axial direction, and the suction nozzle 32 and the suction casing of the suction casing 3. 3 between the rectangular flow path cross-sectional area A1 (= a1 × b1) at the junction of the annular flow path 33 formed inside 3 and the axial flow path 34 inside the suction casing 3 and the centrifugal impeller 2. The value of the ratio A1 / As with the minimum flow path cross-sectional area As (= π × (r sh 2 −r h 2 )) to be formed is 2.5 or more as shown in FIG. 3 described later. It is set.

ここで、環状流路３３の合流部における長方形の流路断面積Ａ１を形成する一方の一辺となるａ１は、図１及び図２に示すように、吸込ケーシング３の内部に形成した環状流路３３の半径ｒ２と吸込ケーシング３の吸込ノズル３２の流路が接する半径方向位置における流路断面積Ａ１の幅方向寸法であり、前記流路断面積Ａ１を形成する他方の一辺となるｂ１は、流路断面積Ａ１の軸方向寸法である。   Here, a1 which becomes one side which forms the rectangular flow-path cross-sectional area A1 in the confluence | merging part of the annular flow path 33 is the annular flow path formed in the inside of the suction casing 3, as shown in FIG.1 and FIG.2. 33 is a width direction dimension of the channel cross-sectional area A1 at the radial position where the radius r2 of 33 and the flow path of the suction nozzle 32 of the suction casing 3 are in contact, and b1 which is the other side forming the channel cross-sectional area A1 is This is the axial dimension of the channel cross-sectional area A1.

また、図１及び図２に示すように、軸方向流路３４となる遠心羽根車２の初段の最小流路断面積Ａｓを形成するｒｓｈ及びｒｈは、それぞれ遠心羽根車２の初段における軸方向流路３４の最小流路断面積Ａｓを形成する外周側半径及び内周側半径である。 Further, as shown in FIGS. 1 and 2, r sh and r h to form a minimum flow path cross-sectional area As of the first-stage centrifugal impeller 2 as the axial passage 34, the first-stage centrifugal impeller 2, respectively These are the outer peripheral radius and the inner peripheral radius that form the minimum channel cross-sectional area As of the axial channel 34.

そして、本実施例の遠心圧縮機の吸込ケーシング３においては、吸込ケーシング３の内部に形成された環状流路３３において、環状流路３３の半径ｒ２と軸方向寸法ｂ１の積から求まる円筒表面積Ａ２（＝２π×ｒ２×ｂ１）と、軸方向流路３４と遠心羽根車２の間における最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が、後述する図４に示すように、１２〜２４となるように形成している。   In the suction casing 3 of the centrifugal compressor of the present embodiment, in the annular flow path 33 formed inside the suction casing 3, the cylindrical surface area A2 obtained from the product of the radius r2 of the annular flow path 33 and the axial dimension b1. As shown in FIG. 4 to be described later, the value of A2 / As, which is the ratio between (= 2π × r2 × b1) and the minimum flow path cross-sectional area As between the axial flow path 34 and the centrifugal impeller 2, It forms so that it may become 12-24.

なお、本実施例の遠心圧縮機の吸込ケーシング３から流入して羽根車ケーシング４の内部の遠心羽根車２に流れる作動流体１０の流れを、より均一化するために、図２に示すように吸込ケーシング３の内部に形成した環状流路３３の流路内に、吸込ケーシング３の吸込ノズル３２の開口側と、この吸込ノズル３２の開口側の周方向反対側とに旋回防止板３５をそれぞれ設けても良い。   In order to make the flow of the working fluid 10 flowing from the suction casing 3 of the centrifugal compressor of the present embodiment and flowing into the centrifugal impeller 2 inside the impeller casing 4 more uniform, as shown in FIG. In the flow path of the annular flow path 33 formed inside the suction casing 3, the anti-rotation plates 35 are respectively provided on the opening side of the suction nozzle 32 of the suction casing 3 and on the opposite side in the circumferential direction of the opening side of the suction nozzle 32. It may be provided.

また、吸込ケーシング３によって生じる圧力損失がある程度許容できる場合は、特許文献１や特許文献２、および非特許文献１に記載されたように、吸込ケーシング３の内部に流れを導く板を設けることも可能である。   In addition, when the pressure loss caused by the suction casing 3 can be tolerated to some extent, as described in Patent Document 1, Patent Document 2, and Non-Patent Document 1, a plate that guides the flow inside the suction casing 3 may be provided. Is possible.

図３は、図１及び図２に示した第１実施例の遠心圧縮機における吸込ケーシング３の吸込ノズル３２と吸込ケーシング３の内部に形成された環状流路３３の合流部における流路断面積Ａ１と、吸込ケーシング３の内部に形成された軸方向流路３４と遠心羽根車２との間で形成される最小流路断面積Ａｓとの比であるＡ１／Ａｓに対する初段羽根車入口流速偏差ΔＣを示すグラフである。   FIG. 3 is a cross-sectional area of the flow path at the junction of the suction nozzle 32 of the suction casing 3 and the annular flow path 33 formed inside the suction casing 3 in the centrifugal compressor of the first embodiment shown in FIGS. 1 and 2. First stage impeller inlet flow velocity deviation with respect to A1 / As, which is the ratio of A1 to the minimum flow path cross-sectional area As formed between the axial flow path 34 formed inside the suction casing 3 and the centrifugal impeller 2 It is a graph which shows (DELTA) C.

ここで、初段羽根車入口流速偏差ΔＣは、本実施例の遠心圧縮機の吸込ケーシング３の内部に形成された軸方向流路３４と遠心羽根車２との間に形成される最小流路断面積Ａｓにおける作動流体１０の最大流速Ｃｍａｘと最小流速Ｃｍｉｎとの差である。   Here, the first stage impeller inlet flow velocity deviation ΔC is the minimum flow path breakage formed between the axial flow path 34 and the centrifugal impeller 2 formed in the suction casing 3 of the centrifugal compressor of this embodiment. This is the difference between the maximum flow rate Cmax and the minimum flow rate Cmin of the working fluid 10 in the area As.

なお、ここでは流れの周方向均一性を評価するために初段羽根車入口流速偏差ΔＣを用いたが、これに限らず流れ角度や圧力などの流れを表す物理量の同一断面における最大値と最小値の差を用いても構わない。   Here, in order to evaluate the circumferential uniformity of the flow, the first stage impeller inlet flow velocity deviation ΔC is used, but not limited to this, the maximum value and the minimum value in the same cross section of the physical quantity representing the flow such as the flow angle and the pressure. The difference may be used.

図３に示した初段羽根車入口流速偏差ΔＣのグラフから理解できるように、本実施例の遠心圧縮機の吸込ケーシング３においては、流路断面積Ａ１と最小流路断面積Ａｓとの比であるＡ１／Ａｓは、初段羽根車入口流速偏差ΔＣと相関が強い形状パラメータであり、白抜きの矢印で示したように、前記Ａ１／Ａｓの値が２．５より小さいと羽根車入口流速偏差ΔＣが急激に増大することがわかる。   As can be understood from the graph of the first stage impeller inlet flow velocity deviation ΔC shown in FIG. 3, in the suction casing 3 of the centrifugal compressor of the present embodiment, the ratio of the flow passage cross-sectional area A1 and the minimum flow passage cross-sectional area As. A1 / As is a shape parameter having a strong correlation with the first stage impeller inlet flow velocity deviation ΔC, and as indicated by the white arrow, if the value of A1 / As is smaller than 2.5, the impeller inlet flow velocity deviation is It can be seen that ΔC increases rapidly.

流路断面積Ａ１と最小流路断面積Ａｓとの比であるＡ１／Ａｓの値が２．５よりも小さい場合は流路断面積Ａ１が狭すぎることを意味しており、吸込ケーシング３の吸込ノズル３２から吸込ケーシング３の内部に形成された環状流路３３へ作動流体１０が流入する際の流速が速すぎるために、流入した作動流体１０は吸込ノズル３２から環状流路３３の全周に広がること無く軸方向流路３４へ向かう流れが支配的になる。   If the value of A1 / As, which is the ratio of the channel cross-sectional area A1 and the minimum channel cross-sectional area As, is smaller than 2.5, it means that the channel cross-sectional area A1 is too narrow. Since the flow speed when the working fluid 10 flows from the suction nozzle 32 into the annular flow path 33 formed inside the suction casing 3 is too high, the flow of the working fluid 10 flows from the suction nozzle 32 to the entire circumference of the annular flow path 33. The flow toward the axial flow path 34 is dominant without spreading.

この結果、吸込ケーシング３の環状流路３３では作動流体１０の流れが環状流路３３の全周に広がり難くなり、環状流路３３から軸方向流路３４に流下する作動流体１０の流れは吸込ノズル３２の開口側に偏った流れとなり、環状流路３３の周方向において吸込ノズル３２開口側の流速が速く、該開口部以外の側部部分の流速が遅い不均一な管路速度分布となるので遠心圧縮機の効率を低下させる原因となる。   As a result, in the annular flow path 33 of the suction casing 3, the flow of the working fluid 10 hardly spreads around the entire circumference of the annular flow path 33, and the flow of the working fluid 10 flowing down from the annular flow path 33 to the axial flow path 34 is sucked. The flow is biased toward the opening side of the nozzle 32, and the flow velocity at the opening side of the suction nozzle 32 is high in the circumferential direction of the annular flow path 33, and the flow velocity at the side portion other than the opening portion is low, resulting in an uneven pipe velocity distribution. As a result, the efficiency of the centrifugal compressor is reduced.

そこで、本実施例の遠心圧縮機においては、吸込ケーシング３の内部に形成された環状流路３３の合流部の形状を、環状流路３３の合流部における長方形の流路断面積Ａ１と、吸込ケーシング３の内部の軸方向流路３４と遠心羽根車２との間で形成される最小流路断面積Ａｓとの比であるＡ１／Ａｓの値が、図３に示すように、初段羽根車入口流速偏差ΔＣが急激に増加し始める２．５以上になるように設定する。   Therefore, in the centrifugal compressor of the present embodiment, the shape of the merged portion of the annular flow path 33 formed inside the suction casing 3 is changed to the rectangular flow path cross-sectional area A1 in the merged portion of the annular flow path 33, and the suction As shown in FIG. 3, the first stage impeller is a value of A1 / As, which is the ratio of the minimum flow path cross-sectional area As formed between the axial flow path 34 inside the casing 3 and the centrifugal impeller 2. The inlet flow velocity deviation ΔC is set to be 2.5 or more which starts to increase rapidly.

この場合、遠心羽根車２に流入する作動流体１０の流量に対する遠心圧縮機の効率変化の特性において、環状流路３３から軸方向流路３４に流入する作動流体１０の流れが周方向に均一、かつ軸方向に並行して流下することが可能となり、よって作動流体１０が吸込ケーシング３の環状流路３３から軸方向流路３４の遠心羽根車２へ流入する場合に問題となるような遠心圧縮機の効率を低下させる現象は見られない。   In this case, in the characteristic of the efficiency change of the centrifugal compressor with respect to the flow rate of the working fluid 10 flowing into the centrifugal impeller 2, the flow of the working fluid 10 flowing from the annular flow path 33 into the axial flow path 34 is uniform in the circumferential direction. In addition, it is possible to flow down in parallel in the axial direction, so that the centrifugal compression is problematic when the working fluid 10 flows from the annular flow path 33 of the suction casing 3 into the centrifugal impeller 2 of the axial flow path 34. There is no phenomenon that reduces the efficiency of the machine.

図４は、図１及び図２に示した本実施例の遠心圧縮機における吸込ケーシング３の内部に形成した環状流路３３において、環状流路半径ｒ２と軸方向流路寸法ｂ１の積から求まる円筒表面積Ａ２と、軸方向流路３４と遠心羽根車２との間で形成される最小流路断面積Ａｓとの比であるＡ２／Ａｓに対する初段羽根車入口流速偏差ΔＣを示すグラフである。   FIG. 4 is obtained from the product of the annular flow path radius r2 and the axial flow path dimension b1 in the annular flow path 33 formed inside the suction casing 3 in the centrifugal compressor of the present embodiment shown in FIGS. It is a graph which shows the first stage impeller inlet flow velocity deviation (DELTA) C with respect to A2 / As which is ratio of cylindrical surface area A2 and the minimum flow-path cross-sectional area As formed between the axial direction flow path 34 and the centrifugal impeller 2. FIG.

なお、ここでは流れの周方向均一性を評価するために初段羽根車入口流速偏差ΔＣを用いたが、これに限らず流れ角度や圧力などの流れを表す物理量の同一断面における最大値と最小値の差を用いても構わない。   Here, in order to evaluate the circumferential uniformity of the flow, the first stage impeller inlet flow velocity deviation ΔC is used, but not limited to this, the maximum value and the minimum value in the same cross section of the physical quantity representing the flow such as the flow angle and the pressure. The difference may be used.

図４に示した初段羽根車入口流速偏差ΔＣのグラフから理解できるように、本実施例の遠心圧縮機の吸込ケーシング３においては、前述した流路断面積Ａ１と最小流路断面積Ａｓとの比であるＡ１／Ａｓの場合と同様に、円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓは、初段羽根車入口流速偏差ΔＣと相関が強い形状パラメータであり、円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が、１２よりも小さいと初段羽根車入口流速偏差ΔＣが急激に増大することがわかる。   As can be understood from the graph of the first stage impeller inlet flow velocity deviation ΔC shown in FIG. 4, in the suction casing 3 of the centrifugal compressor of the present embodiment, the above-described channel cross-sectional area A1 and the minimum channel cross-sectional area As. As in the case of the ratio A1 / As, A2 / As, which is the ratio between the cylindrical surface area A2 and the minimum flow path cross-sectional area As, is a shape parameter that has a strong correlation with the first stage impeller inlet flow velocity deviation ΔC. It can be seen that if the value of A2 / As, which is the ratio of A2 to the minimum flow path cross-sectional area As, is smaller than 12, the first stage impeller inlet flow velocity deviation ΔC increases rapidly.

円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が１２よりも小さい場合は、円筒表面積Ａ２が狭すぎることを意味しており、吸込ケーシング３の吸込ノズル３２から吸込ケーシング３の内部に形成された環状流路３３に流入した作動流体１０は環状流路３３の全周に広がり、吸込ノズル３２の開口側と反対側にまでまわり込むものの、作動流体１０の流速が速すぎるために軸方向流路３４の内周側壁面（すなわち、回転軸２の表面）にぶつかり、流速が遅い渦を形成する。   When the value of A2 / As, which is the ratio between the cylindrical surface area A2 and the minimum flow path cross-sectional area As, is smaller than 12, it means that the cylindrical surface area A2 is too narrow, and suction is performed from the suction nozzle 32 of the suction casing 3. Although the working fluid 10 that has flowed into the annular flow path 33 formed inside the casing 3 spreads over the entire circumference of the annular flow path 33 and circulates to the side opposite to the opening side of the suction nozzle 32, the flow rate of the working fluid 10 is high. Since it is too fast, it collides with the inner peripheral side wall surface of the axial flow path 34 (that is, the surface of the rotating shaft 2) and forms a vortex with a slow flow velocity.

この結果、軸方向流路３４における作動流体１０の周方向の流速分布は、吸込ノズル３２の開口側と反対側部分の流速が遅いような不均一な管路速度分布となる。   As a result, the flow velocity distribution in the circumferential direction of the working fluid 10 in the axial flow path 34 is a non-uniform pipe line velocity distribution in which the flow velocity on the side opposite to the opening side of the suction nozzle 32 is slow.

そこで、本実施例の遠心圧縮機においては、吸込ケーシング３の形状を、円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が、白抜きの矢印で示したように、初段羽根車入口流速偏差ΔＣが急激に増加し始めることのない１２以上の範囲になるように設定する。   Therefore, in the centrifugal compressor of this embodiment, the shape of the suction casing 3 is such that the value of A2 / As, which is the ratio between the cylindrical surface area A2 and the minimum flow path cross-sectional area As, is indicated by a white arrow. The first stage impeller inlet flow velocity deviation ΔC is set to be in a range of 12 or more that does not start to increase rapidly.

この場合、遠心羽根車２に流入する作動流体１０の流量に対する遠心圧縮機の効率変化の特性において、環状流路３３から軸方向流路３４に流入する作動流体１０の流れが周方向に均一、かつ軸方向に並行して流下することが可能となり、よって作動流体１０が吸込ケーシング３の環状流路３３から軸方向流路３４の遠心羽根車２へ流入する場合に対して問題となるような遠心圧縮機の効率を低下させる現象は見られない。   In this case, in the characteristic of the efficiency change of the centrifugal compressor with respect to the flow rate of the working fluid 10 flowing into the centrifugal impeller 2, the flow of the working fluid 10 flowing from the annular flow path 33 into the axial flow path 34 is uniform in the circumferential direction. In addition, it is possible to flow down in parallel in the axial direction, so that it becomes a problem for the case where the working fluid 10 flows from the annular flow path 33 of the suction casing 3 into the centrifugal impeller 2 of the axial flow path 34. There is no phenomenon that reduces the efficiency of the centrifugal compressor.

ところで、本実施例における多段遠心圧縮機の吸込ケーシング３では、吸込ケーシング３の環状流路３３から軸方向流路３４の遠心羽根車２へ流入する作動流体１０の周方向の流れ分布を均一化するためには、吸込ケーシング３の吸込ノズル３２と吸込ケーシング３の内部に形成された環状流路３３の合流部における幅方向流路寸法ａ１を、吸込ノズル３２と環状流路３３とが接合できる範囲で、前記環状流路３３の環状流路半径ｒ２の２倍と同等の寸法となるａ１≒２×ｒ２の寸法に設定して吸込ケーシング３を形成することが望ましい。   By the way, in the suction casing 3 of the multistage centrifugal compressor in the present embodiment, the flow distribution in the circumferential direction of the working fluid 10 flowing from the annular flow path 33 of the suction casing 3 into the centrifugal impeller 2 of the axial flow path 34 is made uniform. In order to do this, the suction nozzle 32 and the annular flow path 33 can be joined to the width direction flow path dimension a1 at the junction of the suction flow path 32 formed in the suction casing 3 and the suction flow path 3. Preferably, the suction casing 3 is formed so as to have a dimension of a1≈2 × r2, which is a dimension equivalent to twice the annular channel radius r2 of the annular channel 33.

但し、多段遠心圧縮機の吸込ケーシング３の製作上の制約から、幅方向流路寸法ａ１が、ａ１≒２×ｒ２、となる形状に構成に製作することが困難な場合には、図５に示した初段羽根車入口流速偏差ΔＣのグラフから理解できるように、本実施例の遠心圧縮機の吸込ケーシング３における環状流路３３の合流部における幅方向流路寸法ａ１は、吸込ケーシング３の環状流路３３における環状流路半径ｒ２の２倍と、環状流路３３の合流部における幅方向流路寸法ａ１との比である２×ｒ２／ａ１の値が、図５中に白抜きの矢印で示したように、初段羽根車入口流速偏差ΔＣがそれほど急激に増加していない２〜４．５の範囲になるように設定しても良い。   However, in the case where it is difficult to produce a configuration in which the width direction flow path dimension a1 is a1≈2 × r2 due to restrictions on the production of the suction casing 3 of the multistage centrifugal compressor, FIG. As can be understood from the graph of the first stage impeller inlet flow velocity deviation ΔC shown in the drawing, the width direction flow path dimension a1 in the joining portion of the annular flow path 33 in the suction casing 3 of the centrifugal compressor of the present embodiment is the annular shape of the suction casing 3. The value of 2 × r 2 / a 1, which is a ratio of twice the annular flow radius r 2 in the flow passage 33 and the width direction flow passage dimension a 1 at the junction of the annular flow passage 33, is a white arrow in FIG. As indicated by, the first stage impeller inlet flow velocity deviation ΔC may be set in a range of 2 to 4.5 which does not increase so rapidly.

この場合でも、遠心羽根車２に流入する作動流体１０の流量に対する遠心圧縮機の効率変化の特性において、環状流路３３から軸方向流路３４に流入する作動流体１０の流れが周方向にほぼ均一、かつ軸方向にほぼ並行して流下することが可能となり、よって作動流体１０が吸込ケーシング３の環状流路３３から軸方向流路３４の遠心羽根車２へ流入する場合に問題となるような遠心圧縮機の効率を低下させる現象は見られない。   Even in this case, in the characteristic of the change in efficiency of the centrifugal compressor with respect to the flow rate of the working fluid 10 flowing into the centrifugal impeller 2, the flow of the working fluid 10 flowing from the annular flow path 33 to the axial flow path 34 is substantially in the circumferential direction. It is possible to flow down in a uniform and substantially parallel to the axial direction, so that it becomes a problem when the working fluid 10 flows from the annular flow path 33 of the suction casing 3 into the centrifugal impeller 2 of the axial flow path 34. The phenomenon which reduces the efficiency of a simple centrifugal compressor is not seen.

したがって、第１実施例である多段遠心圧縮機では吸込ケーシング３の形状は、図３の流路断面積Ａ１と最小流路断面積Ａｓとの比であるＡ１／Ａｓの値が、２．５以上で、かつ図４の円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が、１２以上の範囲になるように、吸込ケーシング３の吸込ノズル３２と環状流路３３の合流部における断面形状を決める幅方向流路寸法ａ１及び軸方向流路寸法ｂ１と、環状流路３３の環状流路半径ｒ２を設定して吸込ケーシング３を製作すれば、吸込ケーシング内部に気流の圧力損失を生じる整流部材を設置することなく、遠心圧縮機の吸込ケーシングに流入する気流の吸込流れの均一化が可能となる。   Therefore, in the multistage centrifugal compressor of the first embodiment, the shape of the suction casing 3 is such that the value of A1 / As, which is the ratio of the flow path cross-sectional area A1 and the minimum flow path cross-sectional area As of FIG. The suction nozzle 32 and the annular flow path 33 of the suction casing 3 are as described above so that the value of A2 / As, which is the ratio of the cylindrical surface area A2 and the minimum flow path cross-sectional area As of FIG. If the suction casing 3 is manufactured by setting the width direction flow path dimension a1 and the axial direction flow path dimension b1 that determine the cross-sectional shape at the merging portion and the annular flow path radius r2 of the annular flow path 33, the air flow is generated inside the suction casing. It is possible to make the suction flow of the airflow flowing into the suction casing of the centrifugal compressor uniform without installing a rectifying member that causes a pressure loss.

この結果、本実施例では、遠心圧縮機の効率低下を抑制した遠心圧縮機の吸込ケーシング、及び遠心圧縮機の吸込ケーシングの設計方法が実現できることになる。   As a result, in this embodiment, it is possible to realize a suction casing for the centrifugal compressor and a method for designing the suction casing for the centrifugal compressor in which the efficiency reduction of the centrifugal compressor is suppressed.

以上の説明から明らかなように、本実施例によれば吸込ケーシング内部に気流の圧力損失を生じる整流部材を設置せずに、遠心圧縮機の吸込ケーシングに流入する気流の吸込流れの均一化を可能にして遠心圧縮機の効率低下を抑制した遠心圧縮機の吸込ケーシング、及び遠心圧縮機の吸込ケーシングの設計方法が実現できる。   As is clear from the above description, according to the present embodiment, the suction flow of the airflow flowing into the suction casing of the centrifugal compressor is made uniform without installing a rectifying member that causes a pressure loss of the airflow inside the suction casing. A design method of the suction casing of the centrifugal compressor and the design of the suction casing of the centrifugal compressor which can suppress the efficiency reduction of the centrifugal compressor can be realized.

図６は本発明の第２実施例に係る多段遠心圧縮機に備えられた吸込ケーシングの構造を示した断面図であり、図１のＡ−Ａ断面に相当する位置での吸込ケーシングの断面図である。   FIG. 6 is a cross-sectional view showing the structure of the suction casing provided in the multistage centrifugal compressor according to the second embodiment of the present invention, and is a cross-sectional view of the suction casing at a position corresponding to the AA cross section of FIG. It is.

本第２実施例の多段遠心圧縮機は図１及び図２を用いて説明した本発明の第１実施例の多段遠心圧縮機と基本的な構造は同じであるので、両者に共通した構成についての説明は省略し、相違する構成についてのみ以下に説明する。   The multistage centrifugal compressor of the second embodiment has the same basic structure as the multistage centrifugal compressor of the first embodiment of the present invention described with reference to FIGS. Will be omitted, and only different configurations will be described below.

図６に示した第２実施例の多段遠心圧縮機における吸込ケーシング３は、吸い込んだ作動流体１０を周方向に均一かつ軸方向に並行して羽根車ケーシング４の内部の遠心羽根車２へ流入させるために、第１実施例の多段遠心圧縮機に備えられた吸込ケーシング３と同様に、吸込ケーシング３の吸込ノズル３２と吸込ケーシング３の内部に形成された環状流路３３の合流部における流路断面積Ａ１と、吸込ケーシング３の内部に形成された軸方向流路３４と遠心羽根車２との間で形成される最小流路断面積Ａｓとの比であるＡ１／Ａｓの値が、白抜きの矢印で示したように、２．５以上となるように設定されている。   The suction casing 3 in the multistage centrifugal compressor of the second embodiment shown in FIG. 6 flows the sucked working fluid 10 into the centrifugal impeller 2 inside the impeller casing 4 in the circumferential direction and in parallel in the axial direction. Therefore, the flow at the junction of the suction nozzle 32 of the suction casing 3 and the annular flow path 33 formed inside the suction casing 3 is similar to the suction casing 3 provided in the multistage centrifugal compressor of the first embodiment. The value of A1 / As, which is the ratio between the road cross-sectional area A1 and the minimum flow path cross-sectional area As formed between the axial flow path 34 formed inside the suction casing 3 and the centrifugal impeller 2, As indicated by the white arrow, it is set to be 2.5 or more.

また、これと同時に、吸込ケーシング３の内部に形成された環状流路３３において、環状流路半径ｒ２と軸方向流路寸法ｂ１の積から求まる円筒表面積Ａ２と、軸方向流路３４と遠心羽根車２の間における最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が、白抜きの矢印で示したように、１２以上となるように設定されている。   At the same time, in the annular channel 33 formed inside the suction casing 3, the cylindrical surface area A2 obtained from the product of the annular channel radius r2 and the axial channel dimension b1, the axial channel 34 and the centrifugal blade The value of A2 / As, which is the ratio to the minimum flow path cross-sectional area As between the cars 2, is set to be 12 or more as shown by the white arrow.

本実施例における多段遠心圧縮機の吸込ケーシング３は、吸込ケーシング３の環状流路３３から軸方向流路３４の遠心羽根車２へ流入する作動流体１０の周方向の流れ分布を、実施例１における多段遠心圧縮機の吸込ケーシング３の形状よりも更に均一化させるために、前記流路断面積Ａ１と最小流路断面積Ａｓとの比である断面積比Ａ１／Ａｓの値が、できるだけ大きくなるように形成している。   The suction casing 3 of the multistage centrifugal compressor according to the present embodiment has a circumferential flow distribution of the working fluid 10 flowing from the annular flow path 33 of the suction casing 3 into the centrifugal impeller 2 of the axial flow path 34 according to the first embodiment. In order to make it more uniform than the shape of the suction casing 3 of the multistage centrifugal compressor, the value of the cross-sectional area ratio A1 / As, which is the ratio of the flow-path cross-sectional area A1 and the minimum flow-path cross-sectional area As, is as large as possible. It is formed to become.

具体的には、図６に示すように、吸込ケーシング３の吸込ノズル３２と吸込ケーシング３の内部に形成された環状流路３３の合流部における幅方向流路寸法ａ１を、吸込ノズル３２と環状流路３３とが接合できる範囲で、前記環状流路３３の環状流路半径ｒ２の２倍と同等の寸法となるａ１≒２×ｒ２の寸法に設定して吸込ケーシング３を形成することが望ましい。   Specifically, as shown in FIG. 6, the width direction channel dimension a <b> 1 at the joining portion of the suction nozzle 32 of the suction casing 3 and the annular channel 33 formed inside the suction casing 3 is expressed as follows. It is desirable to form the suction casing 3 with a dimension of a1≈2 × r2, which is a dimension equivalent to twice the annular channel radius r2 of the annular channel 33 within a range where the channel 33 can be joined. .

図６に示した第２実施例の多段遠心圧縮機の吸込ケーシング３の形状に関しては、図１及び図２に示した第１実施例の遠心圧縮機における吸込ケーシング３の形状と同様に、図３に示す断面積比Ａ１／Ａｓと初段羽根車入口流速偏差ΔＣの相関関係を示すグラフと、図４に示す面積比Ａ２／Ａｓと初段羽根車入口流速偏差ΔＣの相関相関関係を示すグラフが当てはまる。   The shape of the suction casing 3 of the multistage centrifugal compressor of the second embodiment shown in FIG. 6 is similar to the shape of the suction casing 3 of the centrifugal compressor of the first embodiment shown in FIGS. 3 is a graph showing the correlation between the cross-sectional area ratio A1 / As and the first stage impeller inlet flow velocity deviation ΔC, and FIG. 4 is a graph showing the correlation between the area ratio A2 / As and the first stage impeller inlet flow velocity deviation ΔC. apply.

よって第２実施例の多段遠心圧縮機の吸込ケーシング３の形状についても、図３に示された流路断面積Ａ１と最小流路断面積Ａｓとの比であるＡ１／Ａｓの値が初段羽根車入口流速偏差ΔＣが急激に増加し始める２．５以上となるように設定することによって、遠心羽根車２の流量に対する遠心圧縮機の効率変化の特性において、作動流体１０の流れが周方向に均一、かつ、軸方向に並行して遠心羽根車２へ流入する場合に対して問題となるような遠心圧縮機の効率を低下させる現象は見られない。   Therefore, also for the shape of the suction casing 3 of the multistage centrifugal compressor of the second embodiment, the value of A1 / As, which is the ratio of the channel cross-sectional area A1 and the minimum channel cross-sectional area As shown in FIG. By setting the vehicle inlet flow velocity deviation ΔC to be 2.5 or more, which starts to increase rapidly, the flow of the working fluid 10 is changed in the circumferential direction in the characteristics of the efficiency change of the centrifugal compressor with respect to the flow rate of the centrifugal impeller 2. There is no phenomenon that reduces the efficiency of the centrifugal compressor, which becomes a problem when it flows into the centrifugal impeller 2 in a uniform and parallel axial direction.

同様に、第２実施例の多段遠心圧縮機の吸込ケーシング３の形状を、図４に示された円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が、初段羽根車入口流速偏差ΔＣが急激に増加し始めることのない１２以上の範囲になるように設定することによって、遠心羽根車２の流量に対する遠心圧縮機の効率変化の特性において、作動流体１０の流れが周方向に均一かつ軸方向に並行して遠心羽根車２へ流入する場合に対して問題となるような遠心圧縮機の効率を低下させる現象は見られない。   Similarly, the shape of the suction casing 3 of the multistage centrifugal compressor of the second embodiment is such that the value of A2 / As, which is the ratio of the cylindrical surface area A2 and the minimum flow path cross-sectional area As shown in FIG. By setting the vehicle inlet flow velocity deviation ΔC to be in a range of 12 or more that does not start to increase rapidly, the flow of the working fluid 10 is changed in the characteristics of the efficiency change of the centrifugal compressor with respect to the flow rate of the centrifugal impeller 2. There is no phenomenon that reduces the efficiency of the centrifugal compressor, which causes a problem when flowing into the centrifugal impeller 2 uniformly in the circumferential direction and parallel to the axial direction.

したがって、第２実施例である多段遠心圧縮機では吸込ケーシング３の形状は、図３の流路断面積Ａ１と最小流路断面積Ａｓとの比であるＡ１／Ａｓの値が２．５以上で、かつ図４の円筒表面積Ａ２と最小流路断面積Ａｓとの比であるＡ２／Ａｓの値が１２以上の範囲になるように、吸込ケーシング３の吸込ノズル３２と環状流路３３の合流部における断面形状を決める幅方向流路寸法ａ１及び軸方向流路寸法ｂ１と、環状流路３３の環状流路半径ｒ２を決定すれば良い。   Therefore, in the multistage centrifugal compressor of the second embodiment, the shape of the suction casing 3 is such that the value of A1 / As, which is the ratio of the flow path cross-sectional area A1 and the minimum flow path cross-sectional area As of FIG. And the joining of the suction nozzle 32 of the suction casing 3 and the annular flow path 33 so that the value of A2 / As, which is the ratio of the cylindrical surface area A2 of FIG. What is necessary is just to determine the width direction flow path dimension a1 and the axial direction flow path dimension b1 which determine the cross-sectional shape in a part, and the annular flow path radius r2 of the annular flow path 33.

なお、ここでは流れの周方向均一性を評価するために初段羽根車入口流速偏差ΔＣを用いたが、これに限らず流れ角度や圧力などの流れを表す物理量の同一断面における最大値と最小値の差を用いても構わない。   Here, in order to evaluate the circumferential uniformity of the flow, the first stage impeller inlet flow velocity deviation ΔC is used, but not limited to this, the maximum value and the minimum value in the same cross section of the physical quantity representing the flow such as the flow angle and the pressure. The difference may be used.

本実施例によっても、前述した先の実施例と同様に、吸込ケーシング内部に気流の圧力損失を生じる整流部材を設置せずに、遠心圧縮機の吸込ケーシングに流入する気流の吸込流れの均一化を可能にして遠心圧縮機の効率低下を抑制した遠心圧縮機の吸込ケーシング、及び遠心圧縮機の吸込ケーシングの設計方法が実現できる。   Even in this embodiment, similarly to the previous embodiment described above, the suction flow of the airflow flowing into the suction casing of the centrifugal compressor is made uniform without installing a rectifying member that causes a pressure loss of the airflow inside the suction casing. Therefore, it is possible to realize the suction casing of the centrifugal compressor and the design method of the suction casing of the centrifugal compressor which can suppress the efficiency reduction of the centrifugal compressor.

１：回転軸、２：遠心羽根車、３：吸込ケーシング、４：羽根車ケーシング、５：吐出スクロール、７：内部流路、１０：作動流体、３１：吸込口、３２：吸込ノズル、３３：環状流路、３４：軸方向流路、３５：旋回防止板、１００：多段遠心圧縮機。   1: rotating shaft, 2: centrifugal impeller, 3: suction casing, 4: impeller casing, 5: discharge scroll, 7: internal flow path, 10: working fluid, 31: suction port, 32: suction nozzle, 33: Annular flow path, 34: axial flow path, 35: anti-rotation plate, 100: multistage centrifugal compressor.

Claims (4)

回転軸及びこの回転軸の外周に設置されて気流を圧縮する遠心羽根車を内部にそれぞれ収容する羽根車ケーシングと、前記羽根車ケーシングの上流側に設置されており、遠心羽根車の回転軸に対して直交する方向に開口した吸込口から回転軸に対して直交する内向き方向に気流を導く吸込ノズルを備え、この吸込ノズルから流入した回転軸に対して半径方向の流れを全周に広げる環状流路と、この環状流路で導かれた半径方向からの流れを回転軸中心方向に集約するとともに、半径方向から回転軸方向へ流れの向きを転向して気流を遠心羽根車へ導く軸方向流路をその内部に形成した吸込ケーシングから構成される遠心圧縮機の吸込ケーシングにおいて、
前記吸込ケーシングの吸込ノズルと該吸込ケーシングの内部に形成された環状流路の合流部における流路断面積Ａ１と吸込ケーシングの内部に形成された軸方向流路と遠心羽根車の間における最小流路断面積Ａｓの比Ａ１／Ａｓが２．５以上になるように形成すると共に、前記吸込ケーシングの内部に形成された環状流路の環状流路半径と軸方向流路幅の積から求まる円筒表面積Ａ２と前記最小流路断面積Ａｓの比Ａ２／Ａｓが１２以上になるように前記吸込ケーシングの流路形状を形成したことを特徴とする遠心圧縮機の吸込ケーシング。 An impeller casing that accommodates a rotating shaft and a centrifugal impeller that is installed on the outer periphery of the rotating shaft and compresses an airflow, and is installed on the upstream side of the impeller casing. A suction nozzle that guides airflow in an inward direction perpendicular to the rotation axis from a suction port that opens in a direction orthogonal to the rotation axis, and expands the radial flow to the entire circumference with respect to the rotation axis that flows from the suction nozzle. An annular channel and a shaft that collects the flow from the radial direction guided by the annular channel in the direction of the center of the rotation axis and changes the direction of flow from the radial direction to the direction of the rotation axis to guide the airflow to the centrifugal impeller In the suction casing of the centrifugal compressor composed of a suction casing having a directional flow path formed therein,
The minimum flow between the flow passage cross-sectional area A1 at the confluence of the suction nozzle of the suction casing and the annular flow passage formed inside the suction casing, and the axial flow passage formed inside the suction casing and the centrifugal impeller. A cylinder that is formed so that the ratio A1 / As of the road cross-sectional area As is 2.5 or more, and that is obtained from the product of the annular channel radius and the axial channel width of the annular channel formed inside the suction casing. The suction casing of the centrifugal compressor, wherein the suction casing has a channel shape so that a ratio A2 / As of the surface area A2 and the minimum channel cross-sectional area As is 12 or more. 請求項１に記載された遠心圧縮機の吸込ケーシングにおいて、
前記吸込ケーシングの吸込ノズルと該吸込ケーシングの内部に形成された前記環状流路の合流部における流路断面積を構成する幅方向流路寸法ａ１を、前記環状流路の環状流路半径ｒ２の２倍と同等の寸法に形成したことを特徴とする遠心圧縮機の吸込ケーシング。 In the suction casing of the centrifugal compressor according to claim 1,
The width direction channel dimension a1 constituting the channel cross-sectional area at the junction of the annular channel formed inside the suction nozzle and the suction casing is set to the annular channel radius r2 of the annular channel. A suction casing of a centrifugal compressor, characterized in that it is formed in a size equivalent to twice. 請求項１に記載された遠心圧縮機の吸込ケーシングにおいて、
前記吸込ケーシングの吸込ノズルと該吸込ケーシングの内部に形成された前記環状流路の合流部における流路断面形状を構成する幅方向流路寸法ａ１を、前記環状流路の環状流路半径ｒ２の２倍と、幅方向流路寸法ａ１との比である２×ｒ２／ａ１の値が、２〜４．５となるように形成したことを特徴とする遠心圧縮機の吸込ケーシング。 In the suction casing of the centrifugal compressor according to claim 1,
The width direction channel dimension a1 constituting the channel cross-sectional shape at the junction of the suction channel of the suction casing and the annular channel formed inside the suction casing is equal to the annular channel radius r2 of the annular channel. 2. A suction casing for a centrifugal compressor, wherein a value of 2 × r2 / a1, which is a ratio of twice and a width direction flow path dimension a1, is 2 to 4.5. 回転軸及びこの回転軸の外周に設置されて気流を圧縮する遠心羽根車を内部にそれぞれ収容する羽根車ケーシングと、前記羽根車ケーシングの上流側に設置されており、遠心羽根車の回転軸に対して直交する方向に開口した吸込口から回転軸に対して直交する内向き方向に気流を導く吸込ノズルを備え、この吸込ノズルから流入した回転軸に対して半径方向の流れを全周に広げる環状流路と、この環状流路で導かれた半径方向からの流れを回転軸中心方向に集約するとともに、半径方向から回転軸方向へ流れの向きを転向して気流を遠心羽根車へ導く軸方向流路をその内部に形成した吸込ケーシングから構成される遠心圧縮機の吸込ケーシングの設計方法において、
前記吸込ケーシングの吸込ノズルと該吸込ケーシングの内部に形成された環状流路の合流部における流路断面積Ａ１と吸込ケーシングの内部に形成された軸方向流路と遠心羽根車の間における最小流路断面積Ａｓの比Ａ１／Ａｓと、流れを表す物理量の周方向分布を評価するパラメータとの相関グラフを参照して所望の値になるように設定すると共に、前記吸込ケーシングの内部に形成された環状流路の環状流路半径と軸方向流路幅の積から求まる円筒表面積Ａ２と前記最小流路断面積Ａｓの比Ａ２／Ａｓと、流れを表す物理量の周方向分布を評価するパラメータとの相関グラフを参照して所望の値になるように設定して前記吸込ケーシングの吸込ノズルと前記環状流路の合流部における流路断面形状および前記環状流路の環状流路半径を決定することを特徴とする遠心圧縮機の吸込ケーシングの設計方法。 An impeller casing that accommodates a rotating shaft and a centrifugal impeller that is installed on the outer periphery of the rotating shaft and compresses an airflow, and is installed on the upstream side of the impeller casing. A suction nozzle that guides airflow in an inward direction perpendicular to the rotation axis from a suction port that opens in a direction orthogonal to the rotation axis, and expands the radial flow to the entire circumference with respect to the rotation axis that flows from the suction nozzle. An annular channel and a shaft that collects the flow from the radial direction guided by the annular channel in the direction of the center of the rotation axis and changes the direction of flow from the radial direction to the direction of the rotation axis to guide the airflow to the centrifugal impeller In the design method of the suction casing of the centrifugal compressor composed of a suction casing having a directional flow path formed therein,
The minimum flow between the flow passage cross-sectional area A1 at the confluence of the suction nozzle of the suction casing and the annular flow passage formed inside the suction casing, and the axial flow passage formed inside the suction casing and the centrifugal impeller. The ratio is set to a desired value with reference to a correlation graph between the ratio A1 / As of the road cross-sectional area As and the parameter for evaluating the circumferential distribution of the physical quantity representing the flow, and is formed inside the suction casing. A ratio of the cylindrical surface area A2 obtained from the product of the annular channel radius and the axial channel width of the annular channel and the ratio A2 / As of the minimum channel cross-sectional area As, and a parameter for evaluating the circumferential distribution of the physical quantity representing the flow; Referring to the correlation graph, the flow path cross-sectional shape at the joining portion of the suction nozzle of the suction casing and the annular flow path and the annular flow path radius of the annular flow path are determined by setting to a desired value. Suction casing design method of a centrifugal compressor, characterized by.
JP2009165410A 2009-07-14 2009-07-14 Centrifugal compressor suction casing and design method of centrifugal compressor suction casing Active JP5263043B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2009165410A JP5263043B2 (en) 2009-07-14 2009-07-14 Centrifugal compressor suction casing and design method of centrifugal compressor suction casing

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2009165410A JP5263043B2 (en) 2009-07-14 2009-07-14 Centrifugal compressor suction casing and design method of centrifugal compressor suction casing

Publications (2)

Publication Number Publication Date
JP2011021503A true JP2011021503A (en) 2011-02-03
JP5263043B2 JP5263043B2 (en) 2013-08-14

Family

ID=43631798

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2009165410A Active JP5263043B2 (en) 2009-07-14 2009-07-14 Centrifugal compressor suction casing and design method of centrifugal compressor suction casing

Country Status (1)

Country Link
JP (1) JP5263043B2 (en)

Also Published As

Publication number Publication date
JP5263043B2 (en) 2013-08-14

Similar Documents

Publication Publication Date Title
JP5948892B2 (en) Centrifugal compressor
JP6504273B2 (en) Centrifugal compressor
EP3505770B1 (en) Centrifugal compressor and turbocharger
US10273973B2 (en) Centrifugal compressor having an asymmetric self-recirculating casing treatment
CN102221016A (en) Compressor gas flow deflector and compressor incorporating the same
EP2474743B1 (en) Barrel-type multistage pump
WO2013128539A1 (en) Rotary machine
JP6653326B2 (en) Compressor for exhaust turbocharger
US9234526B2 (en) Centrifugal compressor having an asymmetric self-recirculating casing treatment
JP7105563B2 (en) diffuser for centrifugal compressor
US10138898B2 (en) Centrifugal compressor and turbocharger
JP2009133267A (en) Impeller of compressor
JP2007247622A (en) Centrifugal turbo machine
WO2018155458A1 (en) Centrifugal rotary machine
JP5263043B2 (en) Centrifugal compressor suction casing and design method of centrifugal compressor suction casing
JP6775379B2 (en) Impeller and rotating machine
JP6667323B2 (en) Centrifugal rotating machine
JP6279524B2 (en) Centrifugal compressor, turbocharger
JP7461715B2 (en) Compressor
JP2006200489A (en) Centrifugal fluid machine and its suction casing
JP2008163821A (en) Centrifugal compressor
JP2015190391A (en) centrifugal compressor
JP5292110B2 (en) Vortex blower
JP6037996B2 (en) Compressor and gas turbine
JP5430683B2 (en) Centrifugal compressor with non-axisymmetric self-circulating casing treatment

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20110803

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20130110

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20130115

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20130314

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20130402

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20130415

R150 Certificate of patent or registration of utility model

Ref document number: 5263043

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313111

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313111

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350