CN211422717U

CN211422717U - Cooling structure applied to supercritical carbon dioxide turbine

Info

Publication number: CN211422717U
Application number: CN202020113826.XU
Authority: CN
Inventors: 周东; 龚由春; 但光局; 袁小平; 文鑫; 李扬
Original assignee: Chongqing Jiangjin Shipbuilding Industry Co Ltd
Current assignee: Chongqing Jiangjin Shipbuilding Industry Co Ltd
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2020-09-04
Anticipated expiration: 2030-01-19

Abstract

The utility model discloses a be applied to cooling structure of supercritical carbon dioxide turbine, it is used for cooling the temperature sensitive part of carbon dioxide turbine inside, controls the inside temperature field distribution of turbine to realize the inside thrust self-balancing of turbine and the simple characteristics of control strategy. The aim is achieved according to the following method: introducing cold state cooling medium through the cooling gas inlet, bleed casing and bleed casing supporting shoe through the turbine high pressure side, cool off the counter shaft through high pressure side cooling channel, will be taken away through a large amount of heats of axle transmission by first order movable vane and second level movable vane, make the temperature of high pressure end dry gas seal installation department be less than 200 ℃, get into the thrust balance chamber of low pressure section through backflow channel simultaneously, balance shafting thrust, get into low pressure side cooling channel simultaneously, the cooling shafting, the temperature of the dry gas seal installation department of assurance low pressure side is less than 200 ℃.

Description

Cooling structure applied to supercritical carbon dioxide turbine

Technical Field

The utility model relates to a generator technical field especially relates to a be applied to cooling structure of supercritical carbon dioxide turbine.

Background

The supercritical carbon dioxide turbine is a power conversion device applied to a Brayton cycle power generation system using supercritical carbon dioxide as a working medium, has the advantages of high system efficiency, compact structure, high power density, low operation and maintenance cost and the like, and is one of the most promising power generation modes in the future.

The carbon dioxide turbine mainly expands high-temperature and high-pressure gas in the system circulation to do work outwards, and converts the heat energy of the system into mechanical energy to generate electricity. Therefore, the turbine needs to bear double heavy loads of the highest temperature and the highest pressure in the system, meanwhile, a power generation system where the turbine is located is in closed circulation, working media are not allowed to leak, the turbine is required to have good dynamic and static sealing performance, and therefore the dry gas sealing is required to be configured for the turbine to guarantee the leakage requirement. The dry gas seal is sensitive to the temperature, the allowable use temperature is less than or equal to 200 ℃, and the turbine works in a high-temperature environment close to 600 ℃, so that the turbine needs to be cooled.

Supercritical carbon dioxide turbines are a newer product that is currently the world's technology of introduction, most of which are based on laboratory validation phases in design and are less commercially available. In the test equipment, the turbine is not cooled generally because the test equipment does not adopt dry gas sealing and has no high requirement on reliability, sealing performance and the like, and in the commercial application, the turbine needs to be cooled along with the increase of the installed power and the requirements on reliability and sealing performance. Thus, current supercritical carbon dioxide turbine designs have not seen relevant cooling configuration designs.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome prior art not enough, provide a be applied to cooling structure of supercritical carbon dioxide turbine, the utility model discloses can enough realize cooling off the protection to the dry gas seal part of the inside temperature sensitive area of turbine, can guarantee again on the simple easy basis of realizing of control logic that the thrust balance of shafting and the temperature stress between the part are little, still carry out reutilization to cooling gas simultaneously, fully improve cooling efficiency, reduce the cooling gas quantity.

The purpose of the utility model is realized like this:

a cooling structure applied to a supercritical carbon dioxide turbine,

the air entraining device comprises an outer shell and a shaft, wherein the outer shell is provided with a step-shaped inner cavity along the axial direction, an inner shell is arranged in a large-diameter section of the inner cavity of the outer shell, an air entraining shell is arranged at the opening part of the large-diameter section of the inner cavity of the outer shell, a re-air entraining shell is arranged at the opening part of a small-diameter section of the inner cavity of the outer shell, and the shaft penetrates through the outer shell, the inner shell, the air;

the outer shell and the inner shell are radially provided with inlets of supercritical carbon dioxide, the inlets of the supercritical carbon dioxide are adjacent to the air entraining shell, the outer shell is also provided with outlets of the supercritical carbon dioxide, the outlets of the supercritical carbon dioxide are positioned between the inner shell and the air re-entraining shell, and a turbine mechanism is arranged between the inner shell and a shaft corresponding to the positions between the inlets of the supercritical carbon dioxide and the outlets of the supercritical carbon dioxide; the inner ends of the air entraining shell and the air re-entraining shell are provided with grooves along the axial lead direction, a cooling air inlet baffle is arranged in the groove of the air entraining shell, a high-pressure side carbon ring seal is arranged between the cooling air inlet baffle and the shaft, a high-pressure side comb seal is arranged between the inner shell corresponding to an inlet of the supercritical carbon dioxide and the air entraining shell and the shaft, an axial thrust balancing section with increased diameter is arranged on the shaft, the axial projection areas of the high-pressure side thrust surface and the low-pressure side thrust surface of the axial thrust balancing section along the axial direction are equal, the turbine mechanism is arranged on the axial thrust balancing section, and a low-pressure side carbon ring seal is arranged between the small-diameter section and the axial thrust balancing section in the;

a cooling air inlet is axially arranged on the bleed air shell, a high-pressure side cooling channel is formed between the cooling air inlet baffle and the groove bottom of the bleed air shell groove, one end of the high-pressure side cooling channel is communicated with the cooling air inlet, the other end of the high-pressure side cooling channel is connected with a first return channel which is radially arranged on the air entraining shell, a second return channel is arranged on the secondary bleed air shell, the first return channel and the second return channel are communicated through a connecting channel, a low-pressure side axial thrust balance cavity is formed between a low-pressure side thrust surface of the axial thrust balance section and an annular step of the secondary bleed air shell, the second backflow channel is communicated with the low-pressure side axial thrust balance cavity through a cooling cavity, a low-pressure side cooling channel is formed between the low-pressure side carbon ring seal and the axial thrust balance section, a conical piece is sleeved on the axial thrust balance section, and a radial hole is formed in the conical piece to communicate the low-pressure side cooling channel with an outlet of the supercritical carbon dioxide.

Preferably, the bleed air casing, bleed air casing again are the T type, and the bleed air casing, bleed air casing again's little terminal global, step face and shell body cooperation, the bleed air casing, bleed air casing again's main aspects pass through the threaded fastener and fix on the shell body.

Preferably, cavities are arranged on the surfaces of the air-entraining shell and the air-entraining shell, the air-entraining shell and the outer shell in a matched manner, and on the surfaces of the outer shell and the inner shell in a matched manner, and are used for reducing heat exchange.

Preferably, a heat insulation gap is reserved between the small end peripheral surface of the secondary air-entraining shell and the outer shell, and a raised discontinuous matching surface is arranged on the small end peripheral surface of the secondary air-entraining shell and is matched and positioned with the outer shell.

Preferably, the inner shell is in threaded fit with the outer shell, and a seam allowance is arranged in the outer shell to axially position the inner shell.

Preferably, the turbine mechanism comprises a first-stage nozzle ring, a first-stage movable blade shroud, a first-stage movable blade, a second-stage nozzle ring, a second-stage movable blade and a second-stage movable blade shroud.

A cooling method applied to a supercritical carbon dioxide turbine,

cooling gas enters from a cooling gas inlet, enters a first return passage through a high-pressure side cooling passage, cools the high-pressure side of the shaft, reduces the temperature of a dry gas seal installation position of the high-pressure side, keeps balance between the cooling gas and working medium gas at the high-pressure side cooling passage, ensures that the working medium gas cannot leak out, and does not enter a turbine mechanism;

then, cooling gas enters the secondary bleed air shell through the connecting channel and the second return channel;

then, cooling gas enters the low-pressure side axial thrust balancing cavity through the cooling cavity to balance axial thrust, and then the cooling gas passes through the low-pressure side cooling channel to cool the low-pressure side of the shaft, so that the temperature of a dry gas seal installation part of the low-pressure side is reduced;

then, the cooling gas enters the outlet of the supercritical carbon dioxide through the radial holes on the conical piece to be mixed and discharged.

Preferably, the cooling gas inlet is sequentially connected with the pressure sensing device, the valve and the working medium source, the valve is fed back through the pressure sensing device, the valve is adjusted, the pressure of the cooling gas inlet is kept close to the static pressure behind the first-stage turbine nozzle, and then the pressure of the cooling gas at the high-pressure side carbon ring sealing position is kept close to the static pressure between the first-stage turbine nozzle and the first-stage turbine movable blade. The high-temperature working medium between the turbine first-stage nozzle and the turbine first-stage movable vane is prevented from leaking towards the high-pressure side carbon ring seal, and cooling gas is prevented from being mixed into the working medium gas.

Since the technical scheme is used, the utility model discloses an introduce the working medium of cold state, with its at first through turbine high pressure end, turbine inlet end promptly to the surface through turbine shaft flows along cooling channel, and absorbs epaxial heat that transmits for the axle through high temperature turbine blade. Because the working medium in a cold state has low temperature, high pressure and high density and large heat carried by unit volume, the temperature of the cooling gas rises very little after absorbing a large amount of heat transferred by the shafting, and if the cooling gas is directly discharged, the cooling energy is wasted, the cooling flow is increased, and the adverse factors of system efficiency reduction, more complex control strategy and the like can be caused. In order to fully utilize the cooling gas, the cooling gas after cooling the high-pressure side of the turbine is introduced to the low-pressure side shaft part of the turbine in a form of a return pipeline and is used for cooling the area sealed by the low-pressure side dry gas, so that the secondary utilization of the cooling gas is realized, and the using amount of the cooling gas is reduced.

Particularly, when cooling gas enters the interior of the turbine to be cooled, certain pressure adjustment needs to be carried out, the valve is fed back through the pressure sensing device, and in the whole cooling system, only the signal needs to be controlled, so that the whole control strategy is very simple and easy to realize. In the control process, the pressure of a cooling gas inlet is ensured to be close to the static pressure behind a first-stage nozzle of a turbine by adjusting a valve, the static pressure difference between the high-pressure side and the low-pressure side of a shafting is small due to the small pressure drop of the cooling gas passing through a return pipeline, and simultaneously, the projected areas of the surfaces generating thrust at the two ends are basically consistent with the projection area of a rotating shaft in the vertical direction, so that the thrust at the high-pressure end and the thrust at the low-pressure end of the shafting are automatically offset, and the axial thrust is reduced.

Meanwhile, the cooling gas can carry out rapid heat exchange on each part in contact with the cooling gas, in order to reduce the temperature gradient of the parts and the heat absorbed by the cooling gas, the contact between the cooling fluid and the inner shell and the outer shell with higher temperature is isolated in the form of a baffle plate, so that the excessive heat exchange and the excessive temperature gradient are prevented, meanwhile, in the area of indirect contact through other parts, a certain cavity is designed between the corresponding parts to reduce the contact area, the heat transfer between the parts is reduced or blocked, and meanwhile, in some necessary positioning surfaces, the positioning fit is carried out through discontinuities, so that the matching purpose is realized, the contact area between the parts is reduced, and the heat exchange is reduced. By the method, most of heat taken away by the cooling fluid is heat transferred by the movable blades on the shafting, and large temperature stress is not formed on the cooling effect generated on other parts.

Drawings

Fig. 1a is a schematic structural view of the present invention;

FIG. 1b is an enlarged view of a portion of FIG. 1 at P;

fig. 2 is a schematic view of the cooling channel of the present invention.

Reference numerals

In the drawing, 1 is an outer shell, 2 is a bleed housing, 3 is a bleed housing nut, 4 is a bleed housing bolt, 5 is a bleed housing annular cavity, 6 is a cooling air inlet baffle, 7 is a high pressure side carbon ring seal, 8 is a bleed housing support block, 9 is a high pressure side comb seal, 10 is a shaft, 11 is an inner shell, 12 is an inner and outer shell cavity, 13 is a re-bleed housing nut, 14 is a re-bleed housing bolt, 15 is a re-bleed housing, 16 is an axial thrust balance disk, 17 is a low pressure side carbon ring seal, 18 is a re-bleed housing mating surface, 19 is a re-bleed housing cavity, 20 is a high pressure side thrust surface, 21 is a cooling air inlet, 22 is a high pressure side dry air seal mounting location, 23 is a high pressure side cooling channel, 24a is a first cooling return channel, 24b is a second cooling return channel, 25 is a low pressure side cooling channel, 26 is a low pressure side dry air seal mounting location, 27 is low pressure side axial thrust balance chamber, 28 is first stage nozzle ring dog, 29 is first stage nozzle ring, 30 is first stage movable vane tip shroud, 31 is first stage movable vane, 32 is second stage nozzle ring, 33 is second stage movable vane, 34 is second stage movable vane tip shroud, 35 is supercritical carbon dioxide's import, 36 is supercritical carbon dioxide's export, 37 is the cone.

Detailed Description

A cooling structure applied to a supercritical carbon dioxide turbine comprises an outer shell and a shaft, wherein the outer shell is provided with a step-shaped inner cavity along the axial direction, an inner shell is arranged in a large-diameter section of the inner cavity of the outer shell, a bleed air shell is arranged at the opening part of the large-diameter section of the inner cavity of the outer shell, a re-bleed air shell is arranged at the opening part of a small-diameter section of the inner cavity of the outer shell, and the shaft penetrates through the outer shell, the inner shell, the bleed air shell and the re; the two ends of the shaft are supported by bearings, and a bleed air shell supporting block is arranged between the shaft and the bleed air shell. Fig. 1a and 1b show cross-sectional views of the internal structure of a supercritical carbon dioxide turbine. The main flow hot carbon dioxide of the turbine enters the inner shell 11 through the outer shell 1, flows through each stage of moving and

static blades

29, 31, 32 and 33, and then flows out through the inner shell 11 and the outer shell 1 respectively. The outer shell and the outer shell are matched with the inner shell, namely connected with each other in a threaded mode, and the air entraining shell 2 is connected with the outer shell 1 through bolts 4 and nuts 3. And in a local area the heat exchange surface is reduced in the form of an annular cavity 5. The high-pressure side carbon ring seal 7 and the cooling air inlet baffle 6 are fixed together through screws, and large bending stress cannot be formed at the baffle due to low pressure difference between two ends. The bleed air housing support blocks 8 are fixed to the bleed air housing 2 by threaded connection, while ensuring the tightness between them. The bleed housing 15 is fixed to the outer housing by means of bleed housing bolts 14 and bleed housing nuts 13 and is fitted close to the blades with a large clearance, while the fitting of the two components is achieved by means of bleed housing fitting surfaces 18 and is a discontinuous fitting, i.e. the fitting and positioning of the components is achieved and the heat exchange between the two components is also reduced. The air-entraining shell 2 and the outer shell 1 are sealed through a metal sealing gasket, and then the air-entraining shell 15 and the outer shell 1 are also sealed through the metal sealing gasket, so that the gas in the turbine is isolated from the external atmospheric pressure under the high-temperature condition.

A cooling clothes applied to a supercritical carbon dioxide turbine is shown in figure 2, a cooling flow aerodynamic diagram inside the turbine is shown, cooling gas enters from a cooling gas inlet 21, is separated from an inner shell 11 through a cooling gas inlet baffle 6 and is fixed on a bleed air shell 2 through threads, and then enters the surface of a high-pressure end of a shaft 10 along a cooling cavity formed by a bleed air shell supporting block 8 and a high-pressure side carbon ring seal 7, wherein a small part of the cooling gas flows through a small-gap cavity formed by the high-pressure side carbon ring seal 7 and the shaft 10, sequentially enters a high-pressure side comb seal 9 and finally enters between a first-stage nozzle 29 and a first-stage movable blade 31 of the turbine. Most of the cooling gas cools the shafting through the cooling channel 23 formed by the shaft 10 and the bleed air housing support block 8, and enters the first cooling return channel 24a, the connecting channel (not shown) and the second cooling return channel 24b, wherein the connecting channel is a pipeline for connecting the bleed air housing 2 and the bleed air housing 15. After flowing out of the second cooling return channel 24b, the gas enters a low-pressure side axial thrust balance cavity 27 formed by the axial thrust balance disk surface 16 on the shaft 10 and the re-bleed air casing 15, the gas is re-introduced into a low-pressure side cooling channel 25 formed by the re-bleed air casing 15 and the shaft 10, the low-pressure side of the shaft 10 is cooled, the cooled gas enters the low-pressure side carbon ring seal 17, and the cooled gas enters the second-stage movable blade 33 of the turbine, and the low-pressure side carbon ring seal 17 has the function of reducing the cooling flow and the cooling amount entering the interior of the turbine as much as possible on the basis of ensuring the cooling flow.

Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims

1. A cooling structure applied to a supercritical carbon dioxide turbine is characterized in that:

2. The cooling structure for a supercritical carbon dioxide turbine according to claim 1, wherein: the bleed casing, bleed casing again are the T type, and the bleed casing, bleed casing again the global, the step face of tip and the shell body cooperation, the main aspects of bleed casing, bleed casing again pass through the threaded fastener and fix on the shell body.

3. The cooling structure for a supercritical carbon dioxide turbine according to claim 2, wherein: the air-entraining shell, the re-air-entraining shell and the outer shell are matched, and cavities are formed in the surfaces of the outer shell and the inner shell which are matched, so that heat exchange is reduced.

4. The cooling structure for a supercritical carbon dioxide turbine according to claim 2, wherein: a heat insulation gap is reserved between the small end peripheral surface of the secondary air entraining shell and the outer shell, and a raised discontinuous matching surface is arranged on the small end peripheral surface of the secondary air entraining shell and is matched and positioned with the outer shell.

5. The cooling structure for a supercritical carbon dioxide turbine according to claim 1, wherein: the inner shell is in threaded fit with the outer shell, and a seam allowance is arranged in the outer shell and used for axially positioning the inner shell.

6. The cooling structure for a supercritical carbon dioxide turbine according to claim 1, wherein: the turbine mechanism comprises a first-stage nozzle ring, a first-stage movable vane shroud, a first-stage movable vane, a second-stage nozzle ring, a second-stage movable vane and a second-stage movable vane shroud.