1. A cracked gas compressor for a polypropylene device comprises a shell, a main shaft, an impeller, a partition plate, a bearing and a sealing assembly; the method is characterized in that:

the shell is divided into an upper shell and a lower shell from the horizontal plane of the rotating shaft, and the upper shell and the lower shell adopt a welding structure;

the lower casing is fixed on a support of the base, and two air inlet air cylinders and two air outlet air cylinders are arranged below the lower casing;

the compressor is divided into two sections, the interstage of 2-stage compression and 3-stage compression of one section and the interstage of 5-stage compression of the second section of the compressor are provided with a water spraying structure, and 6 water spraying ports are arranged at the corresponding positions on the two sides of the lower shell;

the interstage of the first stage of compression and the second stage of compression of 5 stages of compression of the compressor sets up the structure of oil injection, set up 4 oil jets at the corresponding position of both sides of the lower chassis totally;

six impellers are arranged on the main shaft, four impellers of the first section of compression are arranged in the same direction, two impellers of the second section of compression are arranged in the same direction, but are arranged back to back with the impellers of the first section;

one section of impeller of the compressor adopts four high-efficiency ternary backward bending type and blade equal-strength closed structure; the second section adopts 2 high-efficiency binary backward bending type and blade equal-strength closed structure;

two balance discs are arranged on the main shaft, and the positions of the two balance discs are respectively arranged between the first section and the second section and at the tail end of the second section.

Background

The centrifugal compressor is widely applied to the technical fields of petrochemical industry, metallurgical industry and other industries as a pneumatic machine, and when the centrifugal compressor is designed, various factors need to be considered, such as reduction of production cost; the working efficiency of the compressor is improved. When the use of a user is considered, the process requirements of the device are firstly met, and on the premise of meeting the requirements, the high-quality solution is guaranteed to be provided for the user by considering various factors during the design of the compressor.

At present, the application range of the centrifugal compressor is very wide, for example, the centrifugal compressor is applied in the chemical process, and in order to ensure that certain processes react under higher pressure, gas is compressed to certain pressure; in the application of power engineering, compressor air of a compressor is used as a power air source of a driving device; in gas delivery applications, a compressor is often used to pressurize the feed gas. And the like, and in devices in which apparatuses are all at the core. Each compressor is unique relative to each set of device, different design parameters correspond to different compressors, and the compressors cannot be used universally.

Chinese patent ZL200480039764.6 discloses a "multistage centrifugal compressor and its installation method", which comprises a horizontally openable vessel consisting of a lower half vessel and an upper half vessel, a shaft provided with a series of rotors and a series of stages, each stage comprising a series of lower and upper baffles in sequence; the lower half ring and the upper half ring are characterized in that the lower half partition plate and the upper half partition plate in each stage are respectively strictly restricted by a fixing mechanism. Whereas the securing mechanism is simply an axial screw. This design does not find any significant technical effect.

Chinese utility model patent ZL200920013987.5 discloses a single-shaft multistage centrifugal compressor, including rotor group portion, stator group portion, support bearing and thrust bearing, except that the casing in its stator group portion is the welded structure of horizontal subdivision, divide into upper and lower casing, the structure and the installation order of all the other various parts are all very usual, and not see there is new characteristics.

The two above-mentioned patent documents only illustrate some basic features of the centrifugal compressor and do not describe the compressor used in the specific process flow, but the present invention illustrates the cracked gas compressor used in the polypropylene plant.

Disclosure of Invention

The invention aims at a cracking gas compressor for a polypropylene device, and aims to increase the pressure and the temperature of raw materials input by the device to meet the requirements of process parameters of a subsequent reactor in the polypropylene device.

The invention provides a cracked gas compressor for a polypropylene device, which comprises a shell, a main shaft, an impeller, a partition plate, a bearing and a sealing assembly, wherein the main shaft is arranged on the shell; the method is characterized in that: the shell is divided into an upper shell and a lower shell from the horizontal plane of the rotating shaft, and the upper shell and the lower shell adopt a welding structure; the lower casing is fixed on a support of the base, and two air inlet air cylinders and two air outlet air cylinders are arranged below the lower casing; the compressor is divided into two sections, the interstage of 2-stage compression and 3-stage compression of one section and the interstage of 5-stage compression of the second section of the compressor are provided with a water spraying structure, and 6 water spraying ports are arranged at the corresponding positions on the two sides of the lower shell; the interstage of the first stage of compression and the second stage of compression of 5 stages of compression of the compressor sets up the structure of oil injection, set up 4 oil jets at the corresponding position of both sides of the lower chassis totally; six impellers are arranged on the main shaft, four impellers of the first section of compression are arranged in the same direction, two impellers of the second section of compression are arranged in the same direction, but are arranged back to back with the impellers of the first section; one section of impeller of the compressor adopts four high-efficiency ternary backward bending type and blade equal-strength closed structure; the second section adopts 2 high-efficiency binary backward bending type and blade equal-strength closed structure; two balance discs are arranged on the main shaft, and the positions of the two balance discs are respectively arranged between the first section and the second section and at the tail end of the second section.

The upper shell and the lower shell of the cracking gas compressor adopt steel plates and forgings as raw materials, a plate blank is firstly punched into a semi-cylindrical shape by a large-scale punching machine, then the semi-cylindrical shape is manufactured into parts meeting the requirements of drawings by machining processes such as turning, welding, milling and the like and the parts are arranged on a main shaft to form a rotor set, and the rotor set is arranged in the lower shell and is fixed on the lower shell by nuts and bolts as long as an upper shell is hung on the lower shell; when in maintenance, the nut and the bolt are detached, and the upper shell is lifted by a crane, so that the compressor can be checked and repaired.

The shell of the cracking gas compressor adopts a welding structure, and compared with a casting structure of a traditional compressor, the shell of the cracking gas compressor has the advantages of short processing period, higher qualification rate of the shell, cost saving and guarantee of the delivery cycle of a unit.

The advantages are more prominent for large-scale multi-stage centrifugal compressors. At present, the cracked gas compressor of the invention is provided with a plurality of compressors with different specifications for use in a polypropylene device in related petrochemical enterprises, and the compressors are all highly evaluated by users.

Drawings

FIG. 1 is an overall cross-sectional view of a charge gas compressor of the present invention;

FIG. 2 is an external view of a compressor shell;

FIG. 3 is a side view of the compressor;

fig. 4 is a schematic view of a rotor set of the compressor.

In the above figures: 1, a machine shell; 2, a partition board; 3, sealing; 4 rotor set; 5, a bearing; 6, dry gas sealing is carried out on a driving end; 7, dry gas sealing of a non-driving end; 8, a nut; 9, bolts; 10, oil injection structure; 11 a water spraying structure; 12 an impeller; 13 a main shaft; 14, a spacer bush; 15 middle balance spacer bush; 16 balance disc; 17 locking nuts; 18 thrust disk.

Detailed Description

The invention will be further described and supplemented with reference to the accompanying drawings.

Embodiment 1 cracking gas compressor for polypropylene device

As shown in fig. 1, 2, 3 and 4, the case assembly part 1 is produced and processed respectively; a partition plate group part 2; a seal group part 3; a rotor set section 4; a bearing set portion 5, and the like. The drive end dry gas seal 6 and the non-drive end dry gas seal 7 are of existing construction and are purchased directly from the seal manufacturer.

The method comprises the steps of stamping a Q345R plate into a semi-cylindrical shape, then carrying out turning, drilling, milling and welding to produce and process the shell assembly part 1, designing protruding edge pressing (or combining parts) on two sides of an upper shell and a lower shell, drilling fixing holes on the edge pressing for arranging nuts 8 and bolts 9, coating sealing glue on the edge pressing for sealing, compressing the compressor in two sections, and arranging two air inlets and two air outlets on the lower part of the lower shell. Adopting a QT500-18 casting to produce and process a partition plate group part 2; using LD10 aluminum alloy to make mouth ring, stage and shaft end sealing to form a sealing group part 3; processing six backward bending type constant strength closed impellers 12 by using ASTM A705 alloy steel; machining the compressor main shaft 13 by using a 40NiCrMo7 alloy steel round bar-shaped forging; the rotor assembly 4 is assembled by machining parts such as a spacer 14, an intermediate balance spacer 15, a balance disc 16, a lock nut 17, a thrust disc 18 and the like with 12Cr 13. Then the rotor group part, the baffle group part, the seal group part and the bearing group part are assembled together according to the assembly process requirements, finally the upper shell is arranged on the lower shell, the holes on the blank pressing edges on the two sides of the upper shell and the lower shell are aligned one by one, and the upper shell and the lower shell are fixed into a whole by nuts and bolts, so that the cracked gas compressor for the polypropylene device is successfully manufactured and installed.

Embodiment 2 cracked gas compressor for polypropylene device dragged by steam turbine

Due to the requirements of process parameters, the operation working conditions of the cracked gas compressor for the polypropylene device are three working conditions, the inlet and outlet pressure of each operation working condition is the same, but the flow is different, the rotating speeds of each working condition calculated under the condition of meeting the requirements are different, the normal operation of the compressor under different rotating speeds is ensured, a sufficient steam source is provided on the site of a user, and the device adopts a back pressure steam turbine as a driving mode to meet the change of the rotating speeds under different working conditions.

Embodiment 3 cracked gas compressor for polypropylene device dragged by variable frequency motor

The implementation is similar to that of embodiment 2, and also because of the requirements of process parameters, the operation conditions of the cracked gas compressor for the polypropylene device of the embodiment are three, the inlet and outlet pressure of each operation condition is the same, but the flow rate is different, the calculated rotating speed of each working condition is different under the condition of meeting the requirements, so that the normal operation of the compressor under different rotating speeds is ensured, a user used in the embodiment has no steam source on site, and the user finally selects a variable frequency motor as a driving mode to meet the change of the rotating speed under different working conditions. Compare the steam turbine and pull, the user can additionally purchase one set of converter and come the speed governing for inverter motor, purchases a gear box simultaneously and comes the acceleration rate.

The embodiments are only design schemes proposed according to different use conditions of different users, and after a corresponding security agreement is signed by the user, the schemes provide a prototype for the user to try out a special case with a satisfactory effect, so that more embodiments can be listed. The present invention is not limited to the above-described embodiments, and variations and modifications thereof, which are within the spirit and principle of the invention, may be made by those skilled in the art.