An expandable machine with adjustable coaxiality and a coaxiality adjusting method thereof

Abstract

The application relates to the technical field of expanders, in particular to a coaxiality-adjustable expander and a coaxiality adjusting method thereof, which comprises an air inlet cylinder, an air outlet cylinder, a nozzle ring seat part sleeve, a nozzle ring, an inter-stage gas seal, a bearing seat, a first bearing, a second bearing, a main shaft and a turbine, the air outlet cylinder comprises an outer shell and an inner shell, the air inlet cylinder and the air outlet cylinder and the bearing seat can be respectively machined in a non-combined machining mode, the machining difficulty of the cylinder body is greatly reduced, the selectability of the machining equipment is increased, and great economic efficiency is achieved; the inter-stage gas seal gap value and the coaxiality can be guaranteed through assembly, machining errors are avoided, the wear of the inter-stage gas seal can be avoided, and the pneumatic efficiency can be greatly guaranteed. The coaxiality between bearings depends on the machining precision of the whole machine after cylinder combination, the machining difficulty is increased, and eccentricity is prone to occur in the assembly process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of expander, in particular to a coaxiality adjustable expander and a coaxiality adjusting method thereof. BACKGROUND

[0002] The organic working medium expander is a rotary power machine for converting the energy of organic working medium into mechanical work, and is mainly used for low-temperature heat recovery.

[0003] The size of the dynamic and static gas seal gap is one of the key factors affecting the aerodynamic efficiency of the expander, and the aerodynamic efficiency will be greatly reduced if the inter-stage gas seal gap is too large. The existing expander is a barrel type cylinder, which has good pressure bearing performance and sealing performance, and the general design value of the gas seal gap is 0.15-0.25mm in radial single side, and the assembly method is direct assembly as a whole. Eccentricity is easy to occur during the assembly process, especially for large bearing span unit, which leads to the accelerated wear of the inter-stage gas seal during the operation of the unit. SUMMARY

[0004] The present application aims to provide a coaxiality adjustable expander and a coaxiality adjusting method thereof, which aims to solve the problem that the coaxiality between the bearings of the existing expander depends on the machining accuracy of the whole machine after the cylinder is combined, which increases the machining difficulty and makes the eccentricity easy to occur during the assembly process.

[0005] To achieve the above-mentioned purpose, in the first aspect, the present application provides a coaxiality adjustable expander, which comprises an inlet cylinder, an exhaust cylinder, a nozzle ring seat part sleeve, a nozzle ring, an inter-stage gas seal, a bearing seat, a first bearing, a second bearing, a main shaft and a turbine, wherein the exhaust cylinder comprises an outer shell and an inner shell;

[0006] The inlet cylinder is detachably connected with the outer shell and located on one side of the outer shell, the inner shell is fixedly connected with the outer shell and located on the inner side wall of the outer shell, the nozzle ring seat part sleeve is detachably connected with the inlet cylinder and located on the inner side wall of the outer shell, the nozzle ring is arranged in the nozzle ring seat part sleeve, the inter-stage gas seal is arranged on the side of the nozzle ring away from the nozzle ring seat part sleeve, the bearing seat is arranged on the side of the inlet cylinder away from the exhaust cylinder, the main shaft penetrates through the inlet cylinder, the outer shell, the bearing seat and the inner shell, the first bearing is arranged between the bearing seat and the main shaft, the second bearing is arranged between the inner shell and the main shaft, and the turbine is arranged on the side of the main shaft close to the nozzle ring seat part sleeve and connected with the inter-stage gas seal.

[0007] The coaxiality adjustable expander further comprises a first mechanical seal and a second mechanical seal, wherein the first mechanical seal is arranged between the bearing seat and the main shaft, and the second mechanical seal is arranged between the inner shell and the main shaft.

[0008] The inner side wall of the shell and the outer side wall of the inner shell enclose an exhaust flow channel, the nozzle ring and the turbine form a turbine stage flow channel, the input end of the turbine stage flow channel communicates with the non-split intake flow channel, and the output end of the turbine stage flow channel communicates with the exhaust flow channel.

[0009] The intake cylinder and the shell are positioned by setting a split pin to ensure the positioning accuracy during disassembly and reassembly.

[0010] The nozzle ring seat sleeve is split in the middle, and the upper and lower halves are connected by screws, and the nozzle ring seat sleeve as a whole is positioned by setting a split pin to ensure the positioning accuracy during disassembly and reassembly with the shell.

[0011] The coaxial adjustable expander further comprises three coaxial adjustment blocks, a first adjustment gasket and a plurality of fasteners, the three coaxial adjustment blocks are located on the horizontal symmetrical two sides and directly below the bearing seat, the first adjustment gasket is located between the coaxial adjustment blocks and the bearing seat, and the plurality of fasteners are connected with the bearing seat by penetrating the three coaxial adjustment blocks and the first adjustment gasket.

[0012] The coaxial adjustable expander further comprises a nozzle ring positioning key, a nozzle ring adjustment block, a nozzle ring pressing block and a second adjustment gasket, and the nozzle ring positioning key, the nozzle ring adjustment block, the nozzle ring pressing block and the second adjustment gasket are connected between the nozzle ring and the nozzle ring seat sleeve through fasteners.

[0013] The intake cylinder, the shell and the bearing seat are machined in a non-combined manner, and the parallelism of the middle split surface of the intake cylinder, the mounting surface of the intake cylinder and the bearing seat, and the middle split surface of the shell and the mounting surface of the bearing seat is ensured to be within 0.03 mm during machining.

[0014] In a second aspect, the present application provides a coaxial adjustment debugging method of a coaxial adjustable expander, comprising the following steps:

[0015] After the intake cylinder and the exhaust cylinder are combined and assembled, the split pin in the middle split surface is assembled to ensure the reassembly;

[0016] The false shaft penetrates the bearing seat, the intake cylinder, the shell and the inner shell, the first false bearing support is arranged between the intake cylinder and the false shaft through small gap cooperation, and the second false bearing support is arranged between the inner shell and the false shaft through gap cooperation;

[0017] The dial indicator is installed on the end face of the false shaft, the circular runout of the first bearing mounting surface of the bearing seat is measured by rotating the false shaft, the shaft center of the bearing seat is adjusted by adjusting the number of first adjustment gaskets on the bearing seat, and finally the circular runout value is less than 0.03 mm;

[0018] The third false bearing support is arranged between the bearing seat and the false shaft through a gap fit; the second false bearing support and the exhaust cylinder are sequentially disassembled, the nozzle ring seat part sleeve is installed on the side of the intake cylinder close to the exhaust cylinder, the nozzle ring seat part sleeve and the intake cylinder are matched and assembled, and the nozzle ring seat part sleeve and the intake cylinder are assembled; the nozzle ring seat part upper half is disassembled; the nozzle ring seat part lower half is sequentially and stably installed, and the nozzle ring seat part lower half comprises a nozzle ring lower half, an inter-stage gas seal lower half, a nozzle ring middle surface positioning pin and an inter-stage gas seal middle surface positioning pin; the inter-stage gas seal and the nozzle ring are disassembled and connected;

[0019] The axial height direction of the inter-stage gas seal is adjusted through the nozzle ring adjusting block and the second adjusting gasket, the axial horizontal direction of the inter-stage gas seal is adjusted through the nozzle ring positioning key, and the nozzle ring is fixed with the nozzle ring seat part sleeve through the nozzle ring pressing block, so that the coaxiality of the inter-stage gas seal is adjusted.

[0020] The gap value between the false shaft and the inter-stage gas seal is measured respectively until the gap value is within a preset range, and thus the coaxiality and the gap value of the inter-stage gas seal and the rotor are adjusted.

[0021] The false shaft, the first false shaft support, the third false shaft support and the nozzle ring seat part lower half are disassembled, the rotor assembly is installed into the nozzle ring seat part lower half, the nozzle ring part sleeve upper half is sequentially assembled, the nozzle ring part sleeve upper half comprises a nozzle ring upper half and an inter-stage gas seal upper half, the nozzle ring seat part upper half and the lower half are combined and assembled, the nozzle ring seat part and the rotor assembly are integrally hoisted and assembled to the corresponding position of the intake cylinder, the nozzle ring seat part comprises a nozzle ring part and a nozzle ring pressing block, the nozzle ring seat part and the intake cylinder are assembled, and the standard fasteners are fastened; the exhaust cylinder and the intake cylinder are assembled, the intake cylinder and the exhaust cylinder are positioned and assembled, the standard fasteners are fastened, and the mechanical seal and the bearing are sequentially assembled.

[0022] The rotor assembly comprises a main shaft and a turbine.

[0023] The coaxiality adjustable expander comprises an intake cylinder, an exhaust cylinder, a nozzle ring seat part, a nozzle ring, an inter-stage gas seal, a bearing seat, a first bearing, a second bearing, a main shaft and a turbine. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0025] Figure 1 is a sectional view of a coaxial adjustable expander provided by the present application.

[0026] Figure 2 is an assembly drawing of a dummy shaft support and bearing seat.

[0027] Figure 3 is an assembly drawing of a nozzle ring seat.

[0028] Figure 4 is a disassembly schematic view of the lower half of the nozzle ring seat assembly.

[0029] Figure 5 is a disassembly schematic view of the lower half of the nozzle ring seat and bearing seat assembly.

[0030] Figure 6 is a sectional view of the lower half of the nozzle ring seat assembly.

[0031] Figure 7 is Figure 6 is a sectional view along the C-C plane.

[0032] Figure 8 is an adjustment drawing of the bearing seat shaft center.

[0033] Figure 9 is Figure 8 is a sectional view along the E-E plane.

[0034] 1 - intake cylinder, 2 - exhaust cylinder, 3 - outer shell, 4 - inner shell, 5 - nozzle ring seat, 6 - nozzle ring, 7 - inter-stage gas seal, 8 - bearing seat, 9 - first bearing, 10 - second bearing, 11 - main shaft, 12 - turbine, 13 - first mechanical seal, 14 - second mechanical seal, 15 - non-disassembly intake flow channel, 16 - exhaust flow channel, 17 - turbine stage flow channel, 18 - split pin, 19 - coaxial adjustment block, 20 - first adjustment gasket, 21 - fastener, 22 - nozzle ring positioning key, 23 - nozzle ring adjustment block, 24 - nozzle ring pressing block, 25 - second adjustment gasket. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described below in the accompanying drawings, in which like or similar designations denote like or similar elements or components throughout the various figures. The embodiments described below are exemplary and intended to explain the present application, and are not intended to limit the present application.

[0036] Referring to Figures 1 to 9 In a first aspect, the present application provides a coaxiality-adjustable expander, comprising an intake cylinder 1, an exhaust cylinder 2, a nozzle ring seat part sleeve 5, a nozzle ring 6, an inter-stage gas seal 7, a bearing seat 8, a first bearing 9, a second bearing 10, a main shaft 11 and a turbine 12, wherein the exhaust cylinder 2 comprises an outer shell 3 and an inner shell 4;

[0037] The intake cylinder 1 is detachably connected to the outer shell 3 and located on one side of the outer shell 3, the inner shell 4 is fixedly connected to the outer shell 3 and located on the inner side wall of the outer shell 3, the nozzle ring seat part sleeve 5 is detachably connected to the intake cylinder 1 and located on the inner side wall of the outer shell 3, the nozzle ring 6 is arranged in the nozzle ring seat part sleeve 5, the inter-stage gas seal 7 is arranged on the side of the nozzle ring 6 away from the nozzle ring seat part sleeve 5, the bearing seat 8 is arranged on the side of the intake cylinder 1 away from the exhaust cylinder 2, the main shaft 11 penetrates through the intake cylinder 1, the outer shell 3, the bearing seat 8 and the inner shell 4, the first bearing 9 is arranged between the bearing seat 8 and the main shaft 11, the second bearing 10 is arranged between the inner shell 4 and the main shaft 11, and the turbine 12 is arranged on the side of the main shaft 11 close to the nozzle ring seat part sleeve 5 and connected to the inter-stage gas seal 7.

[0038] Specifically, during installation of the coaxiality-adjustable expander, the dummy shaft is passed through the bearing seat 8, the intake cylinder 1, the outer shell 3 and the inner shell 4, the first dummy bearing support is arranged between the intake cylinder 1 and the dummy shaft through clearance fit, the second dummy bearing support is arranged between the inner shell 4 and the dummy shaft through clearance fit, and the third dummy bearing support is arranged between the bearing seat 8 and the dummy shaft through clearance fit; the dial indicator is installed on the end face of the dummy shaft, the roundness runout of the first bearing 9 installation face of the bearing seat 8 is measured by rotating the dummy shaft, the shaft center of the bearing seat 8 is adjusted by adjusting the number of the first adjusting shims 20 on the bearing seat 8, and finally the roundness runout value is less than 0.03 mm; the second dummy bearing support and the exhaust cylinder 2 are sequentially disassembled, the nozzle ring seat part sleeve 5 is installed in the outer shell 3, and the nozzle ring 6 is assembled with the split pin 18; the upper half of the nozzle ring seat part sleeve 5 is disassembled; the lower half of each stage nozzle ring 6 part sleeve is sequentially installed, and the inter-stage gas seal is installed on the nozzle ring 6; the inter-stage gas seal shaft center height direction is adjusted through the nozzle ring adjusting block 23 and the second adjusting shims 25, the inter-stage gas seal shaft center horizontal direction is adjusted through the nozzle ring positioning key 22, the nozzle ring pressing block 24 fixes the nozzle ring 6 and the nozzle ring seat part sleeve 5, so as to adjust the shaft center of the inter-stage gas seal; the gap value between the dummy shaft and the inter-stage gas seal is measured respectively until the gap value is within the preset range, at this time, the coaxiality of the inter-stage gas seal and the rotor and the gap value adjustment are completed; the lower half of the nozzle ring 6 part sleeve is disassembled, the rotor assembly is installed into the lower half of the nozzle ring seat part sleeve 5, the upper half of the nozzle ring 6 part sleeve is sequentially assembled, then the upper half and the lower half of the nozzle ring seat part sleeve 5 are assembled, the nozzle ring seat part sleeve 5 part sleeve and the rotor assembly are integrally hoisted and assembled to the corresponding position of the intake cylinder 1, the nozzle ring seat part sleeve 5 and the intake cylinder 1 split pin 18 are assembled, and the standard fasteners 21 are fastened; the exhaust cylinder 2 and the outer shell 3 of the intake cylinder 1 are assembled, the intake cylinder 1 and the exhaust cylinder 2 split pin 18 are positioned, and the standard fasteners 21 are fastened; the mechanical seal and the bearing are sequentially assembled.

[0039] Further, the coaxiality-adjustable expander further comprises a first mechanical seal 13 and a second mechanical seal 14, the first mechanical seal 13 is arranged between the bearing seat 8 and the main shaft 11, and the second mechanical seal 14 is arranged between the inner shell 4 and the main shaft 11. The coaxiality-adjustable expander further comprises three coaxiality adjustment blocks 19, a first adjustment gasket 20 and a plurality of fasteners 21, the three coaxiality adjustment blocks 19 are located on both sides and directly below the horizontally symmetrical bearing seat 8, the first adjustment gasket 20 is located between the coaxiality adjustment block 19 and the bearing seat 8, and the plurality of fasteners 21 are respectively connected with the bearing seat 8 through the three coaxiality adjustment blocks 19 and the first adjustment gasket 20. The coaxiality-adjustable expander further comprises a nozzle ring positioning key 22, a nozzle ring adjustment block 23, a nozzle ring pressing block 24 and a second adjustment gasket 25, and the nozzle ring positioning key 22, the nozzle ring adjustment block 23, the nozzle ring pressing block 24 and the second adjustment gasket 25 are connected between the nozzle ring 6 and the nozzle ring seat part sleeve 5 through the fastener 21.

[0040] Specifically, the intake cylinder 1 has a non-split intake flow channel 15, the inner side wall of the outer shell 3 and the outer side wall of the inner shell 4 form an exhaust flow channel 16, the nozzle ring 6 and the turbine 12 form a turbine stage flow channel 17, the input end of the turbine stage flow channel 17 communicates with the non-split intake flow channel 15, and the output end of the turbine stage flow channel 17 communicates with the exhaust flow channel 16. The intake cylinder 1 and the outer shell 3 are detachably connected through the split pin 18; the nozzle ring seat part sleeve 5 is split in the middle, and the upper and lower halves are connected by screws, and the nozzle ring seat part sleeve 5 as a whole is detachably connected with the outer shell 3 through the split pin 18. The intake cylinder 1, the outer shell 3 and the bearing seat 8 are machined in a non-combined manner, respectively, and the parallelism of the middle split surface of the intake cylinder 1, the mounting surface of the intake cylinder 1 and the bearing seat 8, and the middle split surface of the outer shell 3 and the mounting surface of the bearing seat 8 is ensured to be within 0.03 mm during machining. The nozzle ring adjustment block 23 and the second adjustment gasket 25 are used to adjust the axial height direction of the inter-stage gas seal, the nozzle ring positioning key 22 is used to adjust the horizontal direction of the inter-stage gas seal, and the nozzle ring pressing block 24 is used to fix the nozzle ring 6 and the nozzle ring seat part sleeve 5, so as to adjust the axial center of the inter-stage gas seal.

[0041] In a second aspect, the present application provides a coaxiality adjustment method of a coaxiality-adjustable expander, comprising the following steps:

[0042] S0 After the intake cylinder 1 and the exhaust cylinder 2 are assembled, the split pin is assembled to ensure the reassembly;

[0043] S1 passes the dummy shaft through the bearing seat 8, the intake cylinder 1, the outer shell 3 and the inner shell 4, supports the first dummy bearing through a small gap fit between the intake cylinder 1 and the dummy shaft, and supports the second dummy bearing through a gap fit between the inner shell 4 and the dummy shaft;

[0044] S2 installs a dial indicator on the end face of the dummy shaft, rotates the dummy shaft to measure the circular runout of the first bearing 9 mounting surface of the bearing seat 8, adjusts the shaft center of the bearing seat 8 by adjusting the number of first adjusting shims 20 on the bearing seat 8, and finally makes the circular runout value less than 0.03mm;

[0045] S3 supports the third dummy bearing through a gap fit between the bearing seat and the dummy shaft; sequentially disassembles the second dummy bearing support and the exhaust cylinder 2, installs the nozzle ring seat part sleeve 5 on the side of the intake cylinder 1 close to the exhaust cylinder 2, matches and assembles the nozzle ring seat part sleeve and the intake cylinder saddle seam pin; disassembles the upper half of the nozzle ring seat part sleeve 5; sequentially and stably installs the lower half of each stage nozzle ring seat part sleeve, which contains the lower half of the nozzle ring, the lower half of the inter-stage gas seal, the nozzle ring middle surface positioning pin and the inter-stage gas seal middle surface positioning pin; disassembles the connection between the inter-stage gas seal and the nozzle ring;

[0046] S4 adjusts the axial height direction of the inter-stage gas seal through the nozzle ring adjusting block 23 and the second adjusting shims 25, adjusts the horizontal direction of the shaft center of the inter-stage gas seal through the nozzle ring positioning key 22, and fixes the nozzle ring 6 and the nozzle ring seat part sleeve 5 through the nozzle ring pressing block 24, so as to adjust the coaxiality of the inter-stage gas seal;

[0047] S5 respectively measures the gap values between the dummy shaft and the inter-stage gas seal until the gap values are within the preset range, at which time the coaxiality and gap value adjustment of the inter-stage gas seal and the rotor is completed;

[0048] Specifically, the gap values e, f and g between the dummy shaft and the inter-stage gas seal are measured respectively until the values e, f and g are within the range of |e-f|≤0.05 and |g-(e+f) / 2|≤0.05, at which time the coaxiality and gap value adjustment of the inter-stage gas seal and the rotor is completed.

[0049] S6 disassembles the dummy shaft, the first dummy shaft support, the third dummy shaft support and the lower half of the nozzle ring seat part sleeve, installs the rotor assembly into the lower half of the nozzle ring seat part sleeve, sequentially assembles the upper half of the nozzle ring part sleeve, which contains the upper half of the nozzle ring and the upper half of the inter-stage gas seal, and then assembles the upper half and the lower half of the nozzle ring seat part sleeve, which contains the nozzle ring part sleeve and the nozzle ring pressing block. The nozzle ring seat part sleeve 5 is hoisted and assembled to the corresponding position of the intake cylinder 1 in an integral manner, the nozzle ring seat part sleeve 5 and the intake cylinder 1 saddle seam pin 18 are assembled, and the standard fastener 21 is fastened; the exhaust cylinder 2 and the intake cylinder 1 are assembled, the intake cylinder 1 and the exhaust cylinder 2 saddle seam pin 18 are positioned, the standard fastener 21 is fastened, and the mechanical seal and the bearing are sequentially assembled.

[0050] Specifically, the rotor assembly is composed of a main shaft 11 and a turbine 12. The main shaft 11 penetrates the intake cylinder 1, the outer shell 3 and the inner shell 4, the first bearing 9 is arranged between the bearing seat 8 and the main shaft 11, the second bearing 10 is arranged between the inner shell 4 and the main shaft 11, the turbine 12 is arranged on the side of the main shaft 11 close to the nozzle ring seat part sleeve 5 and is connected with the inter-stage gas seal 7, the first mechanical seal 13 is arranged between the bearing seat 8 and the main shaft 11, and the second mechanical seal 14 is arranged between the inner shell 4 and the main shaft 11.

[0051] The above disclosed is only a preferred embodiment of the coaxiality adjustable expander and the coaxiality adjusting method thereof, and of course cannot limit the scope of the present application, and those skilled in the art can understand that all or part of the processes of the above embodiment can be implemented, and equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A coaxiality-adjustable expander, characterized in that, comprising an intake cylinder, an exhaust cylinder, a nozzle ring seat sleeve, a nozzle ring, an inter-stage gas seal, a bearing seat, a first bearing, a second bearing, a main shaft and a turbine, the exhaust cylinder comprising an outer shell and an inner shell; the intake cylinder is detachably connected with the outer shell and located on one side of the outer shell, the inner shell is fixedly connected with the outer shell and located on the inner side of the outer shell, the nozzle ring seat sleeve is detachably connected with the intake cylinder and located on the inner side of the outer shell, the nozzle ring is arranged in the nozzle ring seat sleeve, the inter-stage gas seal is arranged on the side of the nozzle ring away from the nozzle ring seat sleeve, the bearing seat is arranged on the side of the intake cylinder away from the exhaust cylinder, the main shaft penetrates through the intake cylinder, the outer shell, the bearing seat and the inner shell, the first bearing is arranged between the bearing seat and the main shaft, the second bearing is arranged between the inner shell and the main shaft, and the turbine is arranged on the side of the main shaft close to the nozzle ring seat sleeve and connected with the inter-stage gas seal; the intake cylinder and the outer shell are connected through the setting of a split pin to ensure the positioning accuracy of disassembly and reassembly; the nozzle ring seat sleeve is split in the middle, and the upper and lower halves are connected by screws, and the whole nozzle ring seat sleeve is connected through the setting of a split pin to ensure the positioning accuracy of disassembly and reassembly; the coaxiality-adjustable expander further comprises three coaxiality adjustment blocks, a first adjustment gasket and a plurality of fasteners, the three coaxiality adjustment blocks are located on the horizontal symmetrical two sides and directly below the bearing seat, the first adjustment gasket is located between the coaxiality adjustment blocks and the bearing seat, and the plurality of fasteners are connected with the bearing seat by penetrating through the three coaxiality adjustment blocks and the first adjustment gasket respectively; the coaxiality-adjustable expander further comprises a nozzle ring positioning key, a nozzle ring adjustment block, a nozzle ring pressing block and a second adjustment gasket, and the nozzle ring positioning key, the nozzle ring adjustment block, the nozzle ring pressing block and the second adjustment gasket are connected between the nozzle ring and the nozzle ring seat sleeve through fasteners; a coaxiality debugging method applied to the coaxiality-adjustable expander comprises the following steps: after the intake cylinder and the exhaust cylinder are assembled, a split pin is assembled to ensure the reassembly; a dummy shaft penetrates through the bearing seat, the intake cylinder, the outer shell and the inner shell, a first dummy bearing support is arranged between the intake cylinder and the dummy shaft through small gap cooperation, and a second dummy bearing support is arranged between the inner shell and the dummy shaft through gap cooperation; a dial indicator is installed on the end face of the dummy shaft, the first bearing mounting surface of the bearing seat is measured by rotating the dummy shaft, the shaft center of the bearing seat is adjusted by adjusting the number of first adjustment gaskets on the bearing seat, and finally the circular run-out value is less than 0.03mm. The third false bearing support is arranged between the bearing seat and the false shaft through a gap fit; the second false bearing support and the exhaust cylinder are disassembled in sequence, the nozzle ring seat part sleeve is installed on the side of the intake cylinder close to the exhaust cylinder, the nozzle ring seat part sleeve and the riding seam pin are fitted and assembled; the nozzle ring seat part upper half is disassembled; the nozzle ring seat part lower half is stably installed in sequence, the nozzle ring seat part lower half includes the nozzle ring lower half, the inter-stage gas seal lower half, the nozzle ring middle surface positioning pin and the inter-stage gas seal middle surface positioning pin; the inter-stage gas seal and the nozzle ring are disassembled and connected; The inter-stage gas seal axial height direction is adjusted through the nozzle ring adjusting block and the second adjusting gasket, the inter-stage gas seal axial horizontal direction is adjusted through the nozzle ring positioning key, and the nozzle ring is fixed with the nozzle ring seat part through the nozzle ring pressing block, so that the coaxiality of the inter-stage gas seal is adjusted; The gap value between the false shaft and the inter-stage gas seal is measured respectively until the gap value is within the preset range, and thus the coaxiality of the inter-stage gas seal and the rotor and the gap value adjustment are completed; The false shaft, the first false shaft support, the third false shaft support and the nozzle ring seat part lower half are disassembled, the rotor assembly is installed into the nozzle ring seat part lower half, the nozzle ring part upper half including the nozzle ring upper half and the inter-stage gas seal upper half is assembled in sequence, the nozzle ring seat part upper half and the lower half are combined and assembled, the nozzle ring seat part and the rotor assembly are integrally hoisted and assembled to the corresponding position of the intake cylinder, the nozzle ring seat part includes the nozzle ring part and the nozzle ring pressing block, the nozzle ring seat part and the riding seam pin are assembled, and the standard fastener is fastened; the exhaust cylinder and the intake cylinder are assembled, the riding seam pin is positioned, the standard fastener is fastened, the mechanical seal and the bearing are assembled in sequence; and the rotor assembly is the main shaft and the turbine. 2.The coaxiality-adjustable expander of claim 1, wherein the expander further comprises a first mechanical seal and a second mechanical seal, the first mechanical seal is arranged between the bearing seat and the main shaft, and the second mechanical seal is arranged between the inner shell and the main shaft. 3.The coaxiality-adjustable expander of claim 2, wherein the intake cylinder has a non-split intake flow channel, an inner side wall of the outer shell and an outer side wall of the inner shell enclose an exhaust flow channel, the nozzle ring and the turbine form a turbine stage flow channel, an input end of the turbine stage flow channel communicates with the non-split intake flow channel, and an output end of the turbine stage flow channel communicates with the exhaust flow channel. 4.The coaxiality-adjustable expander of claim 1, wherein the intake cylinder, the outer shell and the bearing seat are machined in a non-combined manner, and the parallelism of a middle surface of the intake cylinder, mounting surfaces of the intake cylinder and the bearing seat, a middle surface of the outer shell and a mounting surface of the bearing seat is ensured to be within 0.03 mm during machining. ​ ​ ​

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