CN112983853B - A high-speed turbine structure applied to large flow and large expansion ratio - Google Patents

Abstract

The invention belongs to the field of fluid machinery and the technical field of refrigeration low temperature, and relates to a high-speed turbine structure applied to large flow and large expansion ratio.A forward compression volute, a backward compression volute, an intermediate shell and an expansion volute are sequentially connected, and a nozzle cover plate is arranged between the intermediate shell and the expansion volute; one end of the main shaft is provided with a pair of compression impellers which are arranged back to back, and the other end is provided with an expansion impeller; a pair of gas radial bearings and a pair of gas thrust bearings for supporting the main shaft are arranged inside the middle shell, a small hole is formed in the middle shell, and a filter is arranged at the inlet of the small hole. According to the invention, the two back-to-back compression impellers are arranged on one side of the main shaft, and different flow rates or pressure ratios are distributed, so that the directions of axial forces generated by the two compression impellers are opposite to the directions of axial forces generated by the expansion impeller at the other end of the main shaft, and even completely offset, and faults caused by unbalance of the axial forces are effectively solved.

Description

A high-speed turbine structure applied to large flow and large expansion ratio

technical field

The invention belongs to the field of fluid machinery and the technical field of refrigeration and low temperature, and relates to a high-speed turbine structure applied to a large flow and a large expansion ratio.

Background technique

Turboexpander is a key component necessary for air separation equipment, natural gas liquefaction separation equipment, waste heat recovery and other equipment to obtain cooling capacity and recover expansion work. In a turboexpander, when the working medium expands adiabatically, the temperature and pressure of the working medium decrease while outputting expansion work to the outside. The expansion work output by the turboexpander can be consumed by the coaxially arranged brake fan, and can also be efficiently recycled by the coaxially arranged centrifugal compressor.

In some refrigeration systems or energy recovery systems, the expansion ratio of the expander is relatively high relative to the pressure ratio of the centrifugal compressor. In particular, under the conditions of large expansion ratio and large enthalpy drop, the output work of the expander is large, resulting in compression. The flow of the wheel needs to be large to match the output work of the expansion impeller. The centrifugal compression impeller designed by the conventional design method is often more than 20% larger than the expansion impeller, which easily leads to the problem of unbalanced axial force and larger structure size of the whole machine. is very low, causing most of the output work of the expansion impeller to be wasted.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a high-speed turbine structure applied to a large flow rate and a large expansion ratio to overcome the above-mentioned defects of the prior art.

The technical solution of the present invention to solve the above problem is: a high-speed turbine structure applied to a large flow rate and a large expansion ratio, the special feature of which is that it includes:

Main shaft, forward compression volute, backward compression volute, intermediate casing and expansion volute;

the forward compression volute, the rearward compression volute, the intermediate casing and the expansion volute are connected in sequence, and a nozzle cover plate is arranged between the intermediate casing and the expansion volute;

The main shaft passes through the forward compression volute, the backward compression volute, the intermediate casing and the expansion volute, one end of the main shaft is provided with a pair of compression impellers installed back-to-back, and the other end of the main shaft is provided with an expansion impeller;

A pair of back-to-back installed compression impellers are respectively located in the forward compression volute and the rearward compression volute, and the expansion impeller is located in the expansion volute, and a pair of gas radial bearings and A pair of gas thrust bearings, small holes are arranged on the intermediate casing, and filters are arranged at the inlets of the small holes. Further, the intermediate casing is provided with a second fluid inlet near the rearward compression volute, and the forward compression volute is provided with a third fluid inlet and a second fluid outlet.

Further, a diffuser is provided between the above-mentioned forward compression volute and the backward compression volute, and a third fluid outlet is provided on the backward compression volute, and the third fluid outlet is connected to the forward compression scroll through a pipeline. A third fluid inlet connection of the shell.

Further, the expansion volute described above includes a first fluid inlet and a first fluid outlet. After the fluid enters from the first fluid inlet, it flows through the airflow channel of the expansion volute and then flows into the nozzle cover respectively. The fluid velocity increases and the pressure decreases in the flow channel of the nozzle. Subsequently, the fluid flows uniformly through the expansion impeller from the outlet of the nozzle, continues to expand in the expansion impeller and performs work on the expansion impeller, thereby driving the expansion impeller to rotate, and the expanded fluid flows out through the first fluid outlet on the expansion volute.

Further, the inner diameter of the first fluid outlet of the expansion volute gradually increases from the inside to the outside, which plays a role in diffusing and decelerating the fluid flowing through the first fluid outlet.

Further, a front bearing seat cover plate and a rear bearing seat cover plate are arranged in the above-mentioned intermediate housing.

Further, the above-mentioned pair of gas radial bearings includes a front radial bearing and a rear radial bearing; a pair of gas thrust bearings includes a front thrust bearing and a rear thrust bearing;

The front radial bearing and the front thrust bearing are arranged on the front bearing seat cover plate, and the rear radial bearing and the rear thrust bearing are arranged on the rear bearing seat cover plate.

Further, the above-mentioned gas thrust bearing and gas radial bearing may be dynamic pressure gas bearings or static pressure gas bearings.

Further, the small hole on the above-mentioned intermediate housing is located between the rear bearing seat cover plate and the nozzle cover plate, and the front bearing seat cover plate and the rear bearing seat cover plate are respectively provided with through holes,

The gas can pass through the small hole, and then be sucked by the backward compression impeller through the through holes in the rear bearing cover plate and the front bearing cover plate. When the gas passes through the bearing cover plate, the gas installed on the cover plate can be cooled. Bearing, improve the bearing capacity and stability of the bearing.

Advantages of the present invention:

1) When the high-speed turbomachinery provided by the present invention works, since the two back-to-back compression impellers are on one side of the main shaft, by distributing different flow rates or pressure ratios, the direction of the axial force generated by the two compression impellers can be made to match the direction of the main shaft. The axial force generated by the expansion impeller at the other end is in the opposite direction or even completely canceled, so the failure caused by the unbalanced axial force can be effectively solved.

2) Compact structure and high efficiency. The high-speed turbomachinery provided by the present invention adopts two back-to-back impellers to recover the expansion work with a large amount of air and a large expansion ratio, which can not only effectively reduce the diameter of the impeller to achieve a compact arrangement, but also achieve the purpose of efficient recovery, which not only reduces the The cost also increases the benefit of recycling.

3) The two technical solutions of the high-speed turbomachine with the back-to-back compression impeller structure provided by the present invention can choose series compression or parallel compression according to the actual situation, so as to realize the function of outputting gas with a small pressure ratio and a large flow rate or a gas with a large pressure ratio and a small flow rate. .

4) Long life and high reliability. The high-speed turbomachinery of the present invention adopts gas bearings, including dynamic pressure gas bearings and static pressure gas bearings. No wear, low maintenance cost, and the use of compressed impeller suction to cool the gas bearing to improve bearing capacity and stability. At the same time, the whole machine can be completely oil-free, avoiding the hidden danger of oil-lubricated bearings contaminating the working medium.

Description of drawings

FIG. 1 is a schematic structural diagram of a high-speed turbomachine according to the parallel compression technical solution of the present invention.

FIG. 2 is a schematic structural diagram of a high-speed turbomachine according to the technical solution of series compression of the present invention.

Among them: 1. The first forward compression volute, 2. The second fluid outlet, 3. The main shaft, 4. The first forward compression impeller, 5. The first backward compression impeller, 6. The first backward compression volute , 7, front bearing housing cover, 8, rear bearing housing cover, 9, intermediate housing, 10, nozzle cover, 11, expansion impeller, 12, expansion volute, 13, first fluid inlet, 14, first Two forward compression volutes, 15, Second forward compression impeller, 16, Second backward compression impeller, 17, Diffuser, 18, Second backward compression volute, 19, Second fluid inlet, 20, The third fluid inlet, 21, the third fluid outlet, 22, the first fluid outlet, 23, the small hole.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.

A high-speed turbine structure applied to large flow and large expansion ratio, comprising a main shaft 3, a forward compression volute, a rearward compression volute, an intermediate casing 9 and an expansion volute 12; the forward compression volute, the rearward compression volute The compression volute, the intermediate casing 9 and the expansion volute 12 are connected in sequence, and a nozzle cover 10 is arranged between the intermediate casing 9 and the expansion volute 12; the main shaft 3 passes through the forward compression volute, the rear To the compression volute, the intermediate casing 9 and the expansion volute 12, one end of the main shaft 3 is provided with a pair of compression impellers installed back-to-back, and the other end of the main shaft 3 is provided with an expansion impeller 11; In the compression volute and the backward compression volute, the expansion impeller 11 is located in the expansion volute 12 . A pair of gas radial bearings and a pair of gas thrust bearings are arranged inside the intermediate housing 9 for supporting the main shaft 3 , the intermediate housing 9 is provided with a small hole 23 , and the entrance of the small hole 23 is provided with a small hole 23 . filter.

As a preferred embodiment of the present invention, the intermediate casing 9 is provided with a second fluid inlet 19 near the rearward compression volute, and the forward compression volute is provided with a third fluid inlet 20 and a second fluid outlet 2 .

As a preferred embodiment of the present invention, a diffuser 17 is provided between the forward compression volute and the backward compression volute, and a third fluid outlet 21 is provided on the backward compression volute. The fluid outlet 21 is piped to the third fluid inlet 20 of the forward compression volute.

As a preferred embodiment of the present invention, the expansion volute 12 includes a first fluid inlet 13 and a first fluid outlet 22 .

As a preferred embodiment of the present invention, the inner diameter of the first fluid outlet 22 of the expansion volute 12 gradually increases from the inside to the outside, which plays a role in diffusing and decelerating the fluid flowing through the first fluid outlet 22 .

As a preferred embodiment of the present invention, the intermediate housing 9 is provided with a front bearing seat cover 7 and a rear bearing seat cover 8 .

As a preferred embodiment of the present invention, a pair of gas radial bearings in the intermediate housing 9 includes a front radial bearing and a rear radial bearing; a pair of gas thrust bearings includes a front thrust bearing and a rear thrust bearing ; The front radial bearing and the front thrust bearing are arranged on the front bearing seat cover plate 7, and the rear radial bearing and the rear thrust bearing are arranged on the rear bearing seat cover plate 8.

As a preferred embodiment of the present invention, the gas thrust bearing and the gas radial bearing are dynamic pressure gas bearings or static pressure gas bearings.

As a preferred embodiment of the present invention, the small hole 23 is located between the rear bearing seat cover 8 and the nozzle cover 10 , and the front bearing seat cover 7 and the rear bearing seat cover 8 are respectively provided with through holes.

Example 1:

Referring to FIG. 1 , a high-speed turbine structure applied to large flow and large expansion ratio includes an intermediate casing 9 , a main shaft 3 , and an expansion impeller 11 mounted on one end of the main shaft 3 , which is matched and installed with the expansion impeller 11 . The expansion volute 12 on the intermediate casing 9, the two back-to-back compression impellers (the first forward compression impeller 4, the first backward compression impeller 5) installed on the other end of the main shaft 3, and the The first backward compression volute 6 on the intermediate housing 9 is installed on the first forward compression volute 1 on the first backward compression volute 6 .

The installation position of the two back-to-back compression impellers is located in the center of the backward compression volute 6 . The first forward compression wheel 4 is circumferentially matched with the inlet of the first forward compression volute 1 , and the first backward compression impeller 5 is circumferentially matched with the inlet of the first backward compression volute 6 . Cooperate. The installation position of the expansion impeller 11 is located at the axial center position of the expansion volute 12 . The expansion impeller 11 cooperates with the outlet of the nozzle cover plate 10 in the circumferential direction.

A diffuser is arranged inside the expansion volute 11 , and the inlet of the diffuser is matched with the outlet of the expansion impeller 11 . A first compression inlet section (third fluid inlet 20 ) is arranged inside the first forward compression volute 1 , and the outlet of the first compression inlet section is matched with the inlet of the first forward compression impeller 4 . A second compression inlet section is arranged inside the backward compression volute 6 , and the outlet of the second compression inlet section is matched with the inlet of the backward compression impeller 5 .

A pair of gas radial bearings and a pair of gas thrust bearings are arranged inside the intermediate housing 9 . The front radial bearing and the front thrust bearing are arranged on the front bearing seat cover plate 7 , and the rear radial bearing and the rear thrust bearing are arranged on the rear bearing seat cover plate 8 . The gas thrust bearing and the gas radial bearing may be dynamic pressure gas bearings or static pressure gas bearings.

After passing through the filter to remove impurities, the gas can pass through the small hole 23 on the intermediate housing 9, and then pass through the through holes on the rear bearing cover plate 8 and the front bearing cover plate 7 and be passed through the first rear bearing cover plate 7. When the gas is sucked into the compression impeller 5, when the gas passes through the bearing cover plate, the gas bearing installed on the cover plate can be cooled, and the bearing capacity and stability of the bearing can be improved.

The working principle of the embodiment of the present invention is as follows:

This embodiment is a parallel compression condition. On the side of the expansion impeller 11, the fluid with a certain speed and pressure flows into the first fluid inlet 13 installed on the expansion volute 12, and then flows into the nozzles after passing through the airflow passage of the expansion volute. cover plate 10. The fluid velocity increases and the pressure decreases in the flow channel of the nozzle. Then, the fluid flows uniformly through the expansion impeller 11 from the outlet of the nozzle, continues to expand in the expansion impeller and performs work on the expansion impeller, thereby driving the expansion impeller 11 to rotate. The expanded fluid flows out through the first fluid outlet 22 (diffuser section) on the expansion volute 12 after being diffused and decelerated. The rotation of the expansion impeller 11 will drive the main shaft 3 to rotate, thereby driving the two back-to-back first forward compression impellers 4 and the first backward compression impellers 5 at the other end of the main shaft 3 to rotate.

The low-pressure gas is respectively driven by the first forward centrifugal compression impeller 4 from the inlet (third fluid inlet 20 ) on the first forward compression volute 1 , and the first backward centrifugal compression impeller 5 from the inlet installed on the intermediate casing 9 . (Second fluid inlet 19) suction, the flow velocity increases in the first forward compression impeller 4 and the first backward compression impeller 5, the pressure rises and then enters the common diffuser, the pressure rises, the speed decreases, and is discharged into the common diffuser The compression volute 1 is finally discharged from the outlet (second fluid outlet 2) installed on the compression volute 1.

The back-to-back impellers in the present invention include but are not limited to two identical impellers, as long as the exhaust pressure is the same to facilitate common exhaust, the flow rates of the two impellers can be different, and the axial force of the impellers can be adjusted by distributing different flow rates to balance the expansion. Axial force on the impeller side. In addition, in order to ensure the same diameter of the two impellers, it is necessary to adjust the structural parameters such as the impeller outlet blade height and the impeller outlet blade angle, so as to facilitate the arrangement of the back-to-back impeller structure.

Example 2:

Referring to FIG. 2 , a high-speed turbine structure applied to a large flow rate and a large expansion ratio includes an intermediate casing 9 , a main shaft 3 , and an expansion impeller 11 mounted on one end of the main shaft 3 , which is matched and installed with the expansion impeller 11 . The expansion volute 12 on the intermediate casing 9, the two back-to-back compression impellers (the second forward compression impeller 15, the second backward compression impeller 16) installed on the other end of the main shaft 3 and the The first backward compression volute 6 on the intermediate housing 9 is installed on the first forward compression volute 1 on the first backward compression volute 6 .

The installation position of the two back-to-back compression impellers is located in the center of the backward compression volute 6 . The first forward compression wheel 4 cooperates with the inlet of the second forward compression volute 14 in the circumferential direction, and the second backward compression impeller 16 cooperates with the inlet of the second backward compression volute 18 in the circumferential direction. Cooperate. The installation position of the expansion impeller 11 is located at the axial center position of the expansion volute 12 . The expansion impeller 11 cooperates with the outlet of the nozzle cover plate 10 in the circumferential direction. A diffuser 17 is arranged between the forward compression volute and the rearward compression volute, and a third fluid outlet 21 is arranged on the rearward compression volute, and the third fluid outlet 21 communicates with the forward compression through a pipeline. A third fluid inlet 20 of the volute is connected.

A diffuser section is arranged inside the expansion volute 11 , and the inlet of the diffuser section is matched with the outlet of the expansion impeller 11 . A first compression inlet section (third fluid inlet 20 ) is arranged inside the second forward compression volute 14 , and the outlet of the first compression inlet section is matched with the inlet of the second forward compression impeller 15 . A second compression inlet section is arranged inside the second backward compression volute 18 , and the outlet of the second compression inlet section is matched with the inlet of the second backward compression impeller 16 .

A pair of gas radial bearings and a pair of gas thrust bearings are arranged inside the intermediate housing 9 . The front radial bearing and the front thrust bearing are arranged on the front bearing seat cover plate 7 , and the rear radial bearing and the rear thrust bearing are arranged on the rear bearing seat cover plate 8 . The gas thrust bearing and the gas radial bearing may be dynamic pressure gas bearings or static pressure gas bearings.

After passing through the filter to remove impurities, the gas can pass through the small hole 23 on the intermediate housing 9, and then pass through the through holes on the rear bearing cover 8 and the front bearing cover 7 and be passed through the second rear bearing cover. When the gas is sucked into the compression impeller 16, when the gas passes through the bearing cover, the gas bearing installed on the cover can be cooled, and the bearing capacity and stability of the bearing can be improved.

The working principle of this embodiment is:

This embodiment is a series compression condition. On the side of the expansion impeller 11, the fluid with a certain speed and pressure flows into the first fluid inlet 13 installed on the expansion volute 12, and then flows into the nozzles after passing through the airflow passage of the expansion volute. cover plate 10. The fluid velocity increases and the pressure decreases in the flow channel of the nozzle. Then, the fluid flows uniformly through the expansion impeller 11 from the outlet of the nozzle, continues to expand in the expansion impeller and performs work on the expansion impeller, thereby driving the expansion impeller 11 to rotate. The expanded fluid flows out through the first fluid outlet 22 (diffuser section) on the expansion volute 12 after being diffused and decelerated. The rotation of the expansion impeller 11 will drive the main shaft 3 to rotate, and then drive the two back-to-back second forward compression impellers 15 and second backward compression impellers 16 at the other end of the main shaft 3 to rotate.

The low pressure gas is sucked by the second backward centrifugal compression impeller 16 from the inlet (second fluid inlet 19) on the intermediate casing 9, compressed in the impeller, the flow rate is accelerated, the pressure rises and then enters the diffuser 17, the pressure rises , the speed is reduced, and it is discharged into the second backward compression volute 18; it enters the inlet of the second forward compression volute 14 through the pipeline, and then enters the second forward compression impeller 15, the pressure rises, the flow rate increases, and then enters the expansion Compressor 17, the pressure increases, the speed decreases, and is discharged into the second forward compression volute 14, and finally the high-pressure gas is discharged from the outlet (second fluid outlet 2) on the second forward compression volute to achieve efficient recovery of expansion work. the goal of. The pressure ratios of the two impellers can be different, and the axial force of the impellers can be adjusted by distributing different pressure ratios to balance the axial force on the expanding impeller side.

The invention adopts two back-to-back impellers to recover the expansion work, not only the impeller diameter is small and the structure is compact, but also the two impellers can be applied in series compression or parallel compression to realize the function of outputting gas with different flow and pressure. At the same time, by distributing the different flow rates of the two impellers and selecting the appropriate inlet pressure under the parallel compression condition, and distributing the different pressure ratios of the two impellers under the series compression condition, the axial force of the two impellers on this side can be adjusted so as to make The overall axial force of the expander achieves self-balance.

Two back-to-back centrifugal compression impellers are used to recover the expansion work. The expansion impeller with a large flow rate and a large expansion ratio has a larger output work. A single compression impeller requires a large flow rate and wheel diameter to recover, resulting in a low efficiency of a single impeller and the size of the parts on the compression side. will also be huge. The use of two back-to-back impellers to recover the expansion work can reduce the diameter of the impeller and achieve high-efficiency recovery of the expansion work on the basis of ensuring compactness.

According to the actual use requirements, the two back-to-back compression impellers can adopt parallel compression or series compression scheme; when parallel compression, the intake pressure of the two impellers is determined according to the actual demand. The intake pressure is high, the braking power of the impeller is large, and the diameter of the impeller can be reduced. In series compression, compared with parallel compression, the total pressure ratio of the impeller is higher and the flow rate is smaller.

The above descriptions are only the embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied to other related The system field is similarly included in the protection scope of the present invention.

Claims (7)

1. The utility model provides a be applied to high-speed turbine structure of big expansion ratio of large-traffic which characterized in that:

comprises a main shaft (3), a forward compression volute, a backward compression volute, an intermediate shell (9) and an expansion volute (12);

the forward compression volute, the backward compression volute, the middle shell (9) and the expansion volute (12) are sequentially connected, and a nozzle cover plate (10) is arranged between the middle shell (9) and the expansion volute (12);

the main shaft (3) penetrates through the forward compression volute, the backward compression volute, the middle shell (9) and the expansion volute (12), one end of the main shaft (3) is provided with a pair of compression impellers which are arranged back to back, and the other end of the main shaft (3) is provided with an expansion impeller (11);

a pair of back-to-back mounted compression impellers are respectively positioned in the forward compression volute and the backward compression volute, and the expansion impeller (11) is positioned in the expansion volute (12);

a pair of gas radial bearings and a pair of gas thrust bearings for supporting the main shaft (3) are arranged in the middle shell (9), a small hole (23) is formed in the middle shell (9), and a filter is arranged at the inlet of the small hole (23);

a front bearing seat cover plate (7) and a rear bearing seat cover plate (8) are arranged in the middle shell (9);

the small hole (23) on the middle shell (9) is positioned between the rear bearing seat cover plate (8) and the nozzle cover plate (10), and the front bearing seat cover plate (7) and the rear bearing seat cover plate (8) are respectively provided with a through hole.

2. The high-speed turbine structure applied to high flow rate and large expansion ratio according to claim 1, characterized in that:

a second fluid inlet (19) is formed in the middle shell (9) and is close to the backward compression volute, and a third fluid inlet (20) and a second fluid outlet (2) are formed in the forward compression volute.

3. The high-speed turbine structure applied to high flow rate and large expansion ratio according to claim 1, characterized in that:

a diffuser (17) is arranged between the forward compression volute and the backward compression volute, a third fluid outlet (21) is arranged on the backward compression volute, and the third fluid outlet (21) is connected with a third fluid inlet (20) of the forward compression volute through a pipeline.

4. A high-speed turbine structure applied to a large flow rate and a large expansion ratio according to claim 2 or 3, wherein:

the expansion volute (12) comprises a first fluid inlet (13) and a first fluid outlet (22).

5. The high-speed turbine structure applied to high flow rate and large expansion ratio according to claim 4, is characterized in that:

the inner diameter of the expansion volute (12) at the first fluid outlet (22) is gradually increased from inside to outside, and the expansion volute plays a role in diffusion and deceleration of fluid flowing through the first fluid outlet (22).

6. The high-speed turbine structure applied to high flow rate and large expansion ratio according to claim 5, wherein:

the pair of gas radial bearings comprises a front radial bearing and a rear radial bearing; the pair of gas thrust bearings comprises a front thrust bearing and a rear thrust bearing; the front radial bearing and the front thrust bearing are arranged on a front bearing seat cover plate (7), and the rear radial bearing and the rear thrust bearing are arranged on a rear bearing seat cover plate (8).

7. The high-speed turbine structure applied to high flow rate and large expansion ratio according to claim 6, wherein:

the gas thrust bearing and the gas radial bearing are dynamic pressure gas bearings or static pressure gas bearings.

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