1. Field of the Invention
The present invention relates to a centrifugal compressor of the type in which disassembly and assembly of the compressor is effected by taking out and inserting internal component parts including end walls for closing ends of a cylindrical rotor chamber wall from and into the cylindrical rotor chamber in the axial direction thereof.
2. Description of the Prior Art
At first, a prior art four-stage centrifugal horizontal split type compressor will be discussed with reference to FIG. 2. In this figure, reference numeral (1) designates a cylindrical rotor chamber wall, numeral (2) designates a main shaft (rotary shaft), numeral (3) designates an intake port, numeral (4) designates a delivery port, numeral (5) designates an intake chamber communicating with the intake port (3), numeral (6) designates an impeller fixedly fitted around the main shaft (2), numeral (7) designates a diffuser, numeral (8) designates a return flow passageway, numeral (9) designates a balance piston fixed to the main shaft (2) on the side of the delivery port (4), numeral (10) designates a propelling force balance chamber formed between the balance piston (9) and an inner axial end surface the rotor chamber wall (1) facing the balance piston (9), numeral (11) designates a balance pipe having its opposite end portions fixedly secured to an outer surface of the rotor chamber wall (1), and the balance pipe (11) is in fluid communication with the above-mentioned propelling force balance chamber (10) and with the aforementioned intake chamber (5). In addition, reference numerals (12) and (13) designate thrust bearings.
In operation, fluid is sucked through the intake port (3) into the intake chamber (5), then it is pressurized and accelerated by the impeller (6) fixedly fitted around the main shaft (2), after the energy of velocity (kinetic energy) has been converted into the energy of pressure (internal energy) by the diffuser (7), the fluid is led through the return flow passageway (8) to an inlet of an impeller in the next stage, then it is pressurized and accelerated by the impeller (6) similarly to the above, and after the energy of velocity has been converted into the energy of pressure by the diffuser (7), the fluid is led through the return flow passageway (8) to an inlet of an impeller in the next stage, and is finally delivered from the delivery port (4). Then, due to differences between fluid pressures exerted upon the opposite sides of the impeller (6) in the respective stages, the rotor including the main shaft (2) and the impellers (6) is propelled from the side of the delivery port (4) towards the side of the intake port (3). Therefore, the balance piston (9) is fixedly secured to the main shaft (2) on the side of the delivery port (4) to form a propelling force balance chamber (10) between the balance chamber piston (9) and an inner axial end surface of the rotor chamber wall (1) facing the balance piston (9). On the other hand, the propelling force balance chamber (10) and the intake chamber (5) are communicated with each other through the balance pipe (11) fixedly secured to the outer surface of the rotor chamber wall (1) to bring the pressure within the propelling force balance chamber (10 close to the pressure within the intake chamber (5), thus the rotor including the main shaft (2) is propelled in the opposite direction by the pressure difference between the front and rear sides of the balance piston (9) to balance out the rotor propelling force, and the residual propelling force towards the intake chamber (5) is supported by the thrust bearings (12) and (13) to prevent the rotor from moving in the axial direction.
In a multi-stage centrifugal compressor operating at a high pressure or a centrifugal compressor dealing with a combustible gas, for the purpose of carrying out inspection and the like, provision is made such that disassembly and assembly of the compressor can be effected by taking out or inserting internal component parts including end walls of a cylindrical rotor chamber wall from and into the cylindrical rotor chamber in the axial direction thereof. A centrifugal compressor having a vertically severing type structure, in which the respective component parts to be mounted within a cylindrical rotor chamber wall can be severed in the direction perpendicular to the axis and can be taken out and inserted in the axial direction, is called a "barrel type centrifugal compressor", and its examples in the prior art are illustrated in FIGS. 3 and 4.
In a centrifugal compressor illustrated in FIG. 3, a rotor chamber is constructed of a cylindrical rotor chamber wall (1a) and end walls (1b) and (1c) closing the opposite ends of the cylindrical rotor chamber wall (1a), an intake chamber (5) is formed inside of the end wall (1b), a propelling force balance chamber (10) is formed between a balance piston (9) fixedly secured to main shaft (2) and the end wall (1c), a communication hole (1b.sub.1) is drilled in the end wall (1b), a communication hole (1c.sub.1) is drilled in the end wall (1c), one end of a first balance pipe section (11a) is fixedly secured to the outer surface of the end wall (1b), one end of a third balance pipe section (11c) is fixedly secured to the outer surface of the end wall (1c), flanges provided at the opposite ends of the above-described respective balance pipe sections (11a) and (11c) are detachably mounted, via bolts, to flanges provided at the opposite ends of a second balance pipe (11b), and threby the propelling force balance chamber (10) and the intake chamber (5) are communicated with each other through the route of the communication hole (1c.sub.1).fwdarw.the third balance pipe section (11c).fwdarw.the second balance pipe section (11b).fwdarw.the first balance pipe section (11a).fwdarw.the communication hole (1b.sub.1). Upon disassembly, the second balance pipe section (11b) is disengaged from the first and third balance pipe sections (11a) and (11c), and then the end walls (1b) and (1c) and the internal component parts (not shown in FIG. 3) are extracted from the interior of the cylindrical rotor chamber wall (1a) in the axial direction (in the left and right directions in this example). Once the inspection or the like has been finished, the end walls (1b) and (1c) and the internal component parts are inserted into the cylindrical rotor chamber wall (1a) in the axial direction (in the left and right directions) to be assembled.
In a centrifugal compressor shown in FIG. 4, a rotor chamber is constructed of a cylindrical rotor chamber wall (1a) and end walls (1b) and (1c) closing the opposite ends of the cylindrical rotor chamber wall (1a), an intake chamber (5) is formed inside of the end wall (1b), a propelling force balance chamber (10) is formed between a balance piston (9) and the end wall (1c), a communiation hole (1c.sub.1) is drilled in the end wall (1c), one end of a first balance pipe section (11a) is fixedly secured to a wall of an intake port (3), one end of a third balance pipe section (11c) is fixedly secured to the outer surface of the end wall (1c), flanges provided at the opposite ends of a second balance pipe section (11b) are detachably mounted by means of bolts to flanges provided at the other ends of the respective balance pipe sections (11a) and (11c), and thereby the propelling force balance chamber (10) is communicated with the intake chamber (5) through the route of the communication hole (1c.sub.1).fwdarw.the third balance pipe section (11c).fwdarw.the second balance pipe section (11b).fwdarw.the first balance pipe section (11a).fwdarw.the intake port (3). Upon disassembly, the second balance pipe section (11b) is disengaged from the first and third balance pipe sections (11a) and (11c), and the end walls (1b) and (1c) and the internal component parts are extracted from the interior of the cylindrical rotor chamber wall (1a) in the axial direction (in the left direction in this example). Once the inspection and the like has been finished, the end walls (1b) and (1c) and the internal component parts are inserted into the cylindrical rotor chamber wall (1a) in the axial direction (in the right direction in this example) to be assembled.
In the horizontally split centrifugal compressors as illustrated in FIG. 2, upon disassembly and assembly of the compressor, it is not necessary to dismount and mount the balance pipe section (11b), while in the vertically split type centrifugal compressor in the prior art as illustrated in FIGS. 3 and 4, upon disassembly and assembly of the compressor, it is necessary to dismount and mount the balance pipe section (11b), but since the balance pipe section (11b) is large in size and heavy in weight, handling thereof is difficult. Moreover, it is necessary to loosen and fasten the bolts for clamping the flanges provided at the opposite ends of the balance pipe section (11b) with the flanges provided at the other ends of the balance pipe sections (11a) and (11c), hence the disassembling and assembling tasks for a centrifugal compressor become complex and troublesome, and so, a working period, a number of working steps and a cost necessitated for disassembly and assembly are increased. In addition, there was a problem that since a large-sized balance pipe section (11b) had to be dismounted and mounted, a large working space was required for disassembly and assembly.