Supercritical condensing, extraction and backpressure type coal-fired heating unit

Abstract

A supercritical condensing, extraction and backpressure type coal-fired heating unit, relating to the field of coal-fired heating unit manufacturing. The heating unit comprises a front bearing housing module (2), a high-intermediate pressure module, an intermediate-low pressure communicating pipe (13), a middle bearing housing module (16), a low pressure module, and a rear bearing housing module (30). The front end of a rotor portion in the high-intermediate pressure module is rigidly connected to a rotor of a generator (1) by means of the front bearing housing module (2); the rear end of the rotor portion in the high-intermediate pressure module is connected to the front end of a rotor portion in the low pressure module by means of the middle bearing housing module (16); the rear end of the rotor portion in the low pressure module is connected to one end of a barring gear short shaft (31) by means of the rear bearing housing module (30); the intermediate-low pressure communicating pipe (13) is arranged between the high-intermediate pressure module and the low pressure module; a steam inlet of the intermediate-low pressure communicating pipe (13) is communicated with an intermediate pressure steam exhaust port of the high-intermediate pressure module; and a steam outlet of the intermediate-low pressure communicating pipe (13) is communicated with a steam inlet of the low pressure module.

Description

A supercritical condensing and extraction coal-fired heating unit Technical Field

[0001] The present application belongs to the field of coal-fired heating unit manufacturing, and specifically relates to a supercritical condensing and extraction coal-fired heating unit. Background Art

[0002] Thermal power units still account for a significant portion of my country's power and heat generation, but most units lack peak-shaving capacity, unable to meet the fluctuations in the overall power system caused by the large-scale grid connection of renewable energy units. To meet the demands of the electricity and heat markets and expand our market share in the thermal power sector, we have developed a supercritical extraction, condensing, and back-pressure steam turbine design suitable for combined heat and power generation with large-capacity extraction steam capability. This single unit, with multiple functions, not only meets the power generation needs of users but also offers high-capacity, high-parameter heating capabilities. The flexible switching between extraction, condensing, and back-pressure operating modes is a heating unit that meets practical needs. Summary of the Invention

[0003] In order to solve the problem that existing heating units cannot meet the fluctuation adjustment of the overall power system caused by the large-scale grid connection of new energy units, this application provides a supercritical condensing and extraction coal-fired heating unit;

[0004] A supercritical condensing and extraction back-fired coal-fired heating unit, the heating unit comprising a front bearing box module, a high- and medium-pressure module, a medium- and low-pressure connecting pipe, a middle bearing box module, a low-pressure module and a rear bearing box module; the front end of the rotor part in the high- and medium-pressure module is rigidly connected to the rotor of the generator through the front bearing box module, the rear end of the rotor part in the high- and medium-pressure module is connected to the front end of the rotor part in the low-pressure module through the middle bearing box, the rear end of the rotor part in the low-pressure module is connected to one end of the turning gear stub shaft through the rear bearing box module, the medium- and low-pressure connecting pipe is arranged between the high- and medium-pressure module and the low-pressure module, the steam inlet of the medium- and low-pressure connecting pipe is connected to the medium-pressure exhaust port of the high- and medium-pressure module, and the steam outlet of the medium- and low-pressure connecting pipe is connected to the steam inlet of the low-pressure module;

[0005] Furthermore, a No. 1 coupling, a front thrust bearing, and a No. 1 support bearing are provided inside the front bearing box module. The front end of the rotor portion in the high- and medium-pressure module is rigidly connected to the rotor of the generator through the No. 1 coupling. The front thrust bearing and the No. 1 support bearing are sleeved on the front end of the high- and medium-pressure rotor in the high- and medium-pressure module.

[0006] Furthermore, the high and medium pressure modules include high and medium pressure outer steam seals, high pressure partition sets, high and medium pressure outer cylinders, high and medium pressure bridge steam seals, high and medium pressure inner cylinders, medium pressure partition sets and high and medium pressure rotors; the high and medium pressure rotors are coaxially sleeved with high pressure partition sets, high and medium pressure inner cylinders and high and medium pressure outer cylinders from the inside to the outside, the high and medium pressure inner cylinders are fixedly connected to the inner wall of the high and medium pressure outer cylinders, the high and medium pressure outer steam seals and medium pressure partition sets are respectively inserted on the inner walls of the front and rear ends of the high and medium pressure outer cylinders, the middle inner wall of the high and medium pressure inner cylinders is coaxially inserted with a high and medium pressure bridge steam seal, the front thrust bearing and the No. 1 support bearing are sleeved on the high At the front end of the intermediate pressure rotor, the front thrust bearing is the relative expansion dead point of the intermediate pressure rotor in the intermediate pressure module and the intermediate shaft in the middle bearing module. The generator rotor, the intermediate pressure rotor and the intermediate shaft expand toward the head and tail respectively with the relative dead point as the boundary. The absolute dead point of the intermediate pressure module is set at the rear of the intermediate pressure outer cylinder. The middle bearing box module is fixedly arranged and rigidly connected to the rear of the intermediate pressure outer cylinder through the intermediate pressure fixed center beam. The front bearing box is slidably arranged and rigidly connected to the front of the intermediate pressure outer cylinder through the intermediate pressure fixed center beam. Relative to the absolute dead point, the intermediate pressure outer cylinder pushes the front bearing to expand toward the head.

[0007] Furthermore, a high-pressure centering beam is provided between the high- and medium-pressure modules and the front bearing box module, one end of the high-pressure centering beam is fixedly connected to the outer wall of the front bearing box module, and the other end of the high-pressure centering beam is fixedly connected to the outer wall of the high- and medium-pressure outer cylinder;

[0008] Furthermore, the high-pressure diaphragm set includes three high-pressure diaphragm sets, which are sequentially sleeved on the high- and medium-pressure rotors along the extension direction of the high-pressure portion of the high- and medium-pressure inner cylinder;

[0009] Furthermore, the middle bearing box module includes a No. 2 coupling, a No. 2 support bearing, an intermediate shaft, a No. 3 support bearing, an SSS clutch, and a No. 4 support bearing. The rear ends of the high and medium pressure rotors are inserted into the middle bearing box module and connected to the front end of the intermediate shaft through the No. 2 coupling. The No. 2 support bearing is arranged between the high and medium pressure rotors and the housing of the middle bearing box module. The No. 3 support bearing is arranged between the intermediate shaft and the housing of the middle bearing box module. The rear end of the intermediate shaft is connected to the rotor part in the low-pressure module through the SSS clutch.

[0010] Furthermore, the low-pressure module includes a low-pressure outer cylinder, a low-pressure rotor, a low-pressure inner cylinder, two exhaust guide rings, two final-stage partition sleeves and two secondary final-stage partition sleeves. The low-pressure rotor is sequentially provided with a low-pressure steam chamber, a low-pressure inner cylinder and a low-pressure outer cylinder from the inside to the outside. The low-pressure inner cylinder is fixedly connected to the inner wall of the low-pressure outer cylinder. The front and rear inner walls of the low-pressure outer cylinder are respectively provided with low-pressure front and rear steam seals. A plurality of pre-twisted blades are installed on the low-pressure steam chamber. The low-pressure positive and negative final-stage partitions, the low-pressure positive and negative secondary final-stage partitions and the low-pressure inner cylinder heat insulation cover are jointly installed on the inner wall of the low-pressure inner cylinder. A low-pressure steam inlet is provided on the upper part of the low-pressure outer cylinder. The low-pressure steam inlet is connected to the medium-pressure exhaust port through a connecting pipe. The front end of the low-pressure rotor is provided with a No. 4 support bearing, which is connected to the medium-pressure exhaust port through the SSS clutch. Connected to the intermediate shaft, the rear end of the low-pressure rotor is successively fitted with the No. 5 support bearing and the rear thrust bearing, which are connected to the front end of the cranking gear short shaft through the No. 3 coupling. The rear thrust bearing is the relative dead point of the low-pressure rotor. The low-pressure rotor and the cranking gear short shaft expand toward the nose and tail respectively with the relative dead point as the boundary. The expansion of the low-pressure rotor and the high- and medium-pressure rotors is absorbed by the SSS clutch. The absolute dead point of the low-pressure outer cylinder is set at the low-pressure steam inlet centerline position. The low-pressure outer cylinder and the low-pressure inner cylinder expand toward the nose and tail respectively with the absolute dead point as the boundary. The middle bearing box and the rear bearing box are fixedly arranged. The two ends of the front and rear low-pressure steam seal bodies are connected to the low-pressure outer cylinder, the middle bearing box and the rear bearing box. The expansion of the low-pressure outer cylinder toward both ends is absorbed by the expansion joints on the front and rear low-pressure steam seal bodies.

[0011] Furthermore, the low-pressure module further includes two low-pressure end steam seals, which are respectively sleeved on one end of the low-pressure rotor, and the low-pressure rotor is sealed with the low-pressure inner cylinder through the two low-pressure end steam seals;

[0012] Furthermore, the rear bearing box module includes a No. 3 coupling, a No. 5 support bearing and a rear thrust bearing. The other end of the low-pressure rotor is connected to one end of the turning gear short shaft through the No. 3 coupling. The No. 5 support bearing is sleeved on the low-pressure rotor, and the inner ring of the No. 5 support bearing is fixedly connected to the low-pressure rotor. The outer ring of the No. 5 support bearing is fixedly connected to the housing of the rear bearing box. The rear thrust bearing is arranged between the No. 5 support bearing and the No. 3 coupling, and the rear thrust bearing is sleeved on the low-pressure rotor.

[0013] Furthermore, the heating unit also includes a valve module, which includes a medium-pressure main steam regulating combined valve, a high-pressure main steam regulating combined valve, a low-pressure main steam regulating combined valve, a shut-off butterfly valve and an adjusting butterfly valve. The high-pressure main steam regulating combined valve is symmetrically arranged on both sides of the high- and medium-pressure outer cylinders. The steam inlet of the high-pressure main steam regulating combined valve is connected to the main steam pipeline of the boiler, and the steam outlet of the high-pressure main steam regulating combined valve is connected to the high-pressure upper and lower steam inlet pipes of the high- and medium-pressure outer cylinders respectively through four steam guide pipes. The medium-pressure main steam regulating combined valve is connected to the high-pressure main steam regulating combined valve. It is arranged on both sides of the high and medium pressure outer cylinders and forms a certain angle. The steam inlet of the medium pressure main steam regulating combined valve is connected to the boiler hot re-pipeline, and the steam outlet of the medium pressure main steam regulating combined valve is connected to the medium pressure lower steam inlet pipe of the high and medium pressure outer cylinders through two steam guide pipes respectively. The shut-off butterfly valve and the adjustment butterfly valve are arranged in series on the medium and low pressure connecting pipes, the low pressure main steam regulating combined valve is connected in parallel with the medium and low pressure connecting pipes, the steam inlet of the low pressure main steam regulating combined valve is connected to the front of the shut-off butterfly valve, and the steam outlet of the low pressure main steam regulating combined valve is connected to the adjustment butterfly valve.

[0014] The beneficial effects of this application compared to the prior art are as follows:

[0015] The present application provides a supercritical condensing and extraction back-fired coal-fired heating unit that adopts a brand-new design concept. The low-pressure cylinders used in the steam turbine can be separated or paralleled according to the operating needs, thus enabling the steam turbine to have a back-pressure operation function. The high-pressure flow is arranged in reverse, the medium-pressure flow is arranged in forward, and the low-pressure flow is arranged symmetrically, with axial thrust self-balancing. The multi-layer cylinder structure is adopted, and the axial clearance of the flow part is large and the radial clearance is small, which has good thermal load adaptability. The flow of the unit is fully designed using a full three-dimensional design method and has been comprehensively optimized.

[0016] The present application provides a supercritical condensing and extraction back-fired coal-fired heating unit, which adopts a layout in which the generator of the unit is placed in front. An SSS clutch is configured between the high-pressure and low-pressure cylinders. The low-pressure cylinder used in the turbine can be separated or paralleled according to operating needs, thereby enabling the turbine to have a back-pressure operation function. At the same time, in order to ensure the correct expansion (contraction) and positioning of components such as the cylinder, and to ensure the correct alignment of the cylinder and the rotor, this turbine is designed with a reasonable sliding pin system. The sliding pin system of this model is very different from that of conventional models. It has two absolute dead points and two relative dead points. The absolute dead point of the high-pressure and high-pressure cylinders is located at the intersection of the center line of the cross key of the middle bearing box and the center line of the turbine, and the absolute dead point of the low-pressure cylinder is located at the intersection of the exhaust center line of the low-pressure cylinder and the center line of the turbine. The high and low pressure cylinders expand toward the front bearing box side at their dead points, and the low pressure cylinder expands toward both sides at its dead point; the two relative dead points in this application are located at the front bearing box of the high and low pressure modules and the rear bearing box of the low pressure module, respectively. The high and low pressure rotors expand toward the low pressure end with the front thrust bearing as the dead point, and the low pressure rotor expands toward the high pressure end with the rear thrust bearing as the dead point. The expansion of the two rotors is absorbed by the SSS clutch connected between the two rotors;

[0017] The present application provides a supercritical condensing and extraction coal-fired heating unit. The medium and low pressure connecting pipes of the unit are equipped with double butterfly valves (shut-off butterfly valve and regulating butterfly valve) in parallel with the low pressure starting valve. The SSS clutch can realize the decoupling and paralleling of the low pressure cylinder. At the same time, a high and medium pressure cylinder structure is adopted. The whole adopts the small enthalpy drop pre-twisted assembly blade technology. The high pressure part is set to 1+14 levels, and the medium pressure part is set to 9 levels. The high and medium pressure flow is symmetrical, and the unit constitutes a single cylinder self-balancing. While ensuring the overall efficiency of the unit, the structure is simplified, the span is shortened, and the cost of the whole machine is reduced;

[0018] The present application provides a supercritical condensing and extraction back-fired coal-fired heating unit, in which the low-pressure module of the unit is arranged symmetrically, with a total design of 2×7 stages, and a new type of welded inner cylinder is used to meet the high-temperature adaptation requirements of the low-pressure module under extreme working conditions, optimize the inner and outer cylinder supports, and the inner cylinder is supported on the outer cylinder skirt to improve the stability of the inner cylinder. The low-pressure bearing box adopts a floor-standing layout, and the shaft system has strong stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic diagram of the layout of the supercritical condensing and extraction coal-fired heating unit described in this application;

[0020] FIG2 is a schematic diagram (top view) of the arrangement of the combined valve body in the supercritical condensing and extraction back-fired coal-fired heating unit described in the present application;

[0021] FIG3 is a longitudinal cross-sectional view of the supercritical condensing and extraction coal-fired heating unit described in the present application;

[0022] FIG4 is a schematic diagram (front view) of the arrangement of the combined valve body in the supercritical condensing and extraction back-fired coal-fired heating unit described in the present application;

[0023] FIG5 is a schematic structural diagram of a synchronous clutch in a supercritical condensing and pumping back coal-fired heating unit according to the present application;

[0024] FIG6 is a schematic diagram of the steam flow of the supercritical condensing and extraction coal-fired heating unit described in this application;

[0025] FIG7 is a schematic diagram of the arrangement of the low-pressure steam valve in the supercritical condensing and extraction coal-fired heating unit described in this application;

[0026] FIG8 is a dead point distribution diagram of the sliding pin system in the supercritical condensing and extraction coal-fired heating unit described in this application;

[0027] In the figure, 1 generator, 2 front bearing box module, 3 front thrust bearing, 4 No. 1 support bearing, 5 high-pressure exhaust balance ring, 6 high-pressure centering beam, 7 high-pressure partition set, 8 high- and medium-pressure outer cylinder, 9 high-pressure inlet balance ring, 10 high- and medium-pressure inner cylinder, 11 medium-pressure partition set, 12 high- and medium-pressure rotor, 13 medium- and low-pressure connecting pipe, 14 No. 2 support bearing, 15 intermediate shaft, 16 middle bearing box module, 17 No. 3 support bearing, 18 SSS clutch, 1 9 No. 4 support bearing, 20 low-pressure end steam seal, 21 low-pressure outer cylinder, 22 exhaust guide ring, 23 low-pressure rotor, 24 last-stage partition sleeve, 25 second-last-stage partition sleeve, 26 low-pressure steam chamber, 27 low-pressure inner cylinder, 28 No. 5 support bearing, 29 rear thrust bearing, 30 rear bearing box module, 31 turning gear short shaft, A medium-pressure main steam regulating combined valve, B high-pressure main steam regulating combined valve, C low-pressure main steam regulating combined valve, D shut-off butterfly valve and E adjusting butterfly valve. DETAILED DESCRIPTION

[0028] Specific embodiment one: This embodiment is explained in conjunction with Figures 1 to 8. In this embodiment, a supercritical condensing and extraction back-fired coal-fired heating unit is provided, and the heating unit includes a front bearing box module 2, a high and medium pressure module, a medium and low pressure connecting pipe 13, a middle bearing box module 16, a low pressure module and a rear bearing box module 30; the front end of the rotor part in the high and medium pressure module is rigidly connected to the rotor of the generator 1 through the front bearing box module 2, the rear end of the rotor part in the high and medium pressure module is connected to the front end of the rotor part in the low pressure module through the middle bearing box 16, and the rear end of the rotor part in the low pressure module is connected to one end of the turning gear short shaft 31 through the rear bearing box module 30, and the medium and low pressure connecting pipe 13 is arranged between the high and medium pressure module and the low pressure module, and the steam inlet of the medium and low pressure connecting pipe 13 is connected to the medium pressure exhaust port of the high and medium pressure module, and the steam outlet of the medium and low pressure connecting pipe 13 is connected to the steam inlet of the low pressure module.

[0029] Specific embodiment 2: This embodiment is described with reference to Figures 1 to 8 . This embodiment differs from Specific embodiment 1 in that a No. 1 coupling, a front thrust bearing 3, and a No. 1 support bearing 4 are installed within the front bearing housing module 2. The front end of the rotor portion of the high- and medium-pressure module is rigidly connected to the rotor of the generator 1 via the No. 1 coupling. The front thrust bearing 3 and the No. 1 support bearing 4 are mounted on the front end of the high- and medium-pressure rotor in the high- and medium-pressure module. Other components and connection methods are the same as those in Specific embodiment 1.

[0030] In combination with the description of specific embodiments one and two, the present application adopts a front-placed arrangement of the generator 1, and rigidly connects the generator 1 to the rotor in the high and medium pressure modules through the front bearing box 2, so that a clutch can be set between the subsequent high and medium pressure modules and the low pressure module, which is convenient for controlling the connection mode between the high and medium pressure modules and the low pressure modules, making the input and release of the low pressure module smoother. In the present application, a double butterfly valve is provided on the medium and low pressure connecting pipe 13, a shut-off butterfly valve and a regulating butterfly valve, which are used to cooperate with the parallel low-pressure starting valve and the SSS clutch in the middle bearing box 16 to realize the low-pressure cylinder decoupling and low-pressure cylinder independent starting and grid connection functions. The No. 1 support bearing 4 used in this embodiment is a tilting pad type, the bearing seat is installed on the bearing box bracket (considered a rigid connection), and a number of pads are installed on the bearing seat. The pads and the rotor are clearance-fitted (not fixedly connected), which facilitates the formation of an oil film.

[0031] Specific embodiment three: This embodiment is described in conjunction with Figures 1 to 8. The difference between this embodiment and specific embodiment two is that the high and medium pressure module includes high and medium pressure outer steam seals 5, high pressure partition set 7, high and medium pressure outer cylinder 8, high and medium pressure bridge steam seal 9, high and medium pressure inner cylinder 10, medium pressure partition set 11 and high and medium pressure rotor 12; the high and medium pressure rotor 12 is coaxially sleeved with high pressure partition set 7, high and medium pressure inner cylinder 10 and high and medium pressure outer cylinder 8 in sequence from inside to outside, the high and medium pressure inner cylinder 10 is fixedly connected to the inner wall of the high and medium pressure outer cylinder 8, the high and medium pressure outer steam seals 5 and the medium pressure partition set 11 are respectively inserted on the inner walls of the front and rear ends of the high and medium pressure outer cylinder 8, and the high and medium pressure bridge steam seal 9 is coaxially inserted on the middle inner wall of the high and medium pressure inner cylinder 10. The front thrust bearing 3 and the No. 1 support bearing 4 are mounted on the front end of the high and medium pressure rotor 12. The front thrust bearing 3 is the relative expansion dead point of the high and medium pressure rotor 12 and the intermediate shaft 15 in the middle bearing module 16 in the high and medium pressure module. The generator rotor and the high and medium pressure rotor 12 and the intermediate shaft 15 expand toward the head and tail respectively with the relative dead point as the boundary. The absolute dead point of the high and medium pressure module is set at the rear of the high and medium pressure outer cylinder 8. The middle bearing box module 16 is fixedly arranged and rigidly connected to the rear of the high and medium pressure outer cylinder 8 through the high and medium pressure fixed center beam 6. The front bearing box 2 is slidingly arranged and rigidly connected to the front of the high and medium pressure outer cylinder 8 through the high and medium pressure fixed center beam 6. Relative to the absolute dead point, the high and medium pressure outer cylinder 8 pushes the front bearing 2 to expand toward the head. Other components and connection methods are the same as those in the second specific embodiment.

[0032] Specific embodiment 4: This embodiment is described with reference to Figures 1 to 8 . This embodiment differs from specific embodiment 3 in that a high-pressure centering beam 6 is provided between the high- and medium-pressure modules and the front bearing box module 2 . One end of the high-pressure centering beam 6 is fixedly connected to the outer wall of the front bearing box module 2 , and the rear end of the high-pressure centering beam 6 is fixedly connected to the outer wall of the high- and medium-pressure outer cylinder 8 . Other components and connection methods are the same as those of specific embodiment 3.

[0033] Specific embodiment 5: This embodiment is described with reference to Figures 1 to 8 . This embodiment differs from specific embodiment 4 in that the high-pressure diaphragm assembly 7 includes three high-pressure diaphragm sleeves, which are sequentially sleeved on the high- and medium-pressure rotors 12 along the extension direction of the high-pressure portion of the high- and medium-pressure inner cylinder 10. The remaining components and connection methods are the same as those of specific embodiment 4.

[0034] As described in Specific Embodiments 3 through 5, the high and medium pressure modules primarily utilize a combined cylinder structure, employing low-enthalpy-drop pre-twisted blade assembly technology. The high-pressure section features 1+14 stages, while the medium-pressure section features 9 stages. Flow paths are symmetrical, and the unit is self-balancing with a single cylinder. This simplifies the structure, shortens the span, and reduces overall unit cost while maintaining overall unit efficiency.

[0035] Specific embodiment six: This embodiment is described in conjunction with Figures 1 to 8. The difference between this embodiment and specific embodiment five is that the middle bearing box module 16 includes a No. 2 coupling, a No. 2 support bearing 14, an intermediate shaft 15, a No. 3 support bearing 17, an SSS clutch 18, and a No. 4 support bearing 19. The rear end of the high and medium pressure rotor 12 is inserted into the middle bearing box module 16 and connected to the front end of the intermediate shaft 15 through the No. 2 coupling. The No. 2 support bearing 14 is arranged between the high and medium pressure rotor 12 and the housing of the middle bearing box module 16. The No. 3 support bearing 17 is arranged between the intermediate shaft 15 and the housing of the middle bearing box module 16. The rear end of the intermediate shaft 15 is connected to the rotor part in the low pressure module through the SSS clutch 18. The No. 4 support bearing 19 is arranged between the rotor part in the low pressure module and the housing of the middle bearing box module 16. Other components and connection methods are the same as those of specific embodiment five.

[0036] Specific embodiment seven: This embodiment is described in conjunction with Figures 1 to 8. The difference between this embodiment and specific embodiment six is ​​that the low-pressure module includes a low-pressure outer cylinder 21, a low-pressure rotor 23, a low-pressure inner cylinder 27, two exhaust guide rings 22, two final-stage baffle sleeves 24 and two secondary final-stage baffle sleeves 25. The low-pressure rotor 23 is sequentially covered with a low-pressure steam chamber 26, a low-pressure inner cylinder 27 and a low-pressure outer cylinder 33 from the inside to the outside. The low-pressure inner cylinder 27 is connected to the low-pressure rotor 23. The inner wall of the high-pressure outer cylinder 21 is fixedly connected, and the inner walls of the front and rear ends of the low-pressure outer cylinder 21 are respectively inserted with low-pressure front and rear steam seal bodies 20, and a plurality of pre-twisted blades are installed on the low-pressure steam chamber 26. The low-pressure positive and negative last-stage partitions 24, the low-pressure positive and negative second-last-stage partitions 25 and the low-pressure inner cylinder heat insulation cover 26 are installed together on the inner wall of the low-pressure inner cylinder 27. A low-pressure steam inlet is provided on the upper part of the low-pressure outer cylinder 21, and the low-pressure steam inlet is connected to the medium-pressure exhaust port through a connecting pipe 13. The low-pressure rotor The front end of 23 is fitted with No. 4 support bearing 19, which is connected to the intermediate shaft 15 through SSS clutch 18. The rear end of the low-pressure rotor 23 is fitted with No. 5 support bearing 28 and rear thrust bearing 29 in sequence, and is connected to the front end of the turning gear short shaft 31 through No. 3 coupling. The rear thrust bearing 29 is the relative dead point of the low-pressure rotor. The low-pressure rotor 23 and the turning gear short shaft 31 expand toward the head and tail respectively with the relative dead point as the boundary, and the expansion of the low-pressure rotor 23 and the high- and medium-pressure rotors 12 is absorbed by the SSS clutch 18. The absolute dead point of the low-pressure outer cylinder 21 is set at the low-pressure steam inlet centerline position. The low-pressure outer cylinder 21 and the low-pressure inner cylinder 27 expand toward the head and tail respectively with the absolute dead point as the boundary. The middle bearing box and the rear bearing box are fixedly arranged. The two ends of the low-pressure front and rear steam seal bodies 20 are connected to the low-pressure outer cylinder, the middle bearing box and the rear bearing box. The expansion joints on the low-pressure front and rear steam seal bodies 20 absorb the expansion of the low-pressure outer cylinder 21 to both ends. Other components and connection methods are the same as those in the sixth embodiment.

[0037] In this embodiment, the middle bearing box 16 is the main component connecting the high and medium pressure modules with the low pressure module. In this application, an SSS clutch is provided in the middle bearing box 16. The SSS clutch is used to adjust the unit to realize the two modes of decoupling and paralleling the units, and the low pressure module can be put into operation and released, so that the steam turbine has a back pressure operation function.

[0038] Specific Embodiment 8: This embodiment is described with reference to Figures 1 to 8 . This embodiment differs from Specific Embodiment 7 in that the low-pressure module further includes two low-pressure end seals 20 , each of which is mounted on one end of a low-pressure rotor 23 . The low-pressure rotor 23 is sealed to the low-pressure inner cylinder 27 via the two low-pressure end seals 20 . Other components and connection methods are the same as those of Specific Embodiment 7 .

[0039] Specific Embodiment 9: This embodiment is described with reference to Figures 1 to 8 . This embodiment differs from Specific Embodiment 8 in that the rear bearing housing module 30 includes a No. 3 coupling, a No. 5 support bearing 28 , and a rear thrust bearing 29 . The other end of the low-pressure rotor 23 is connected to one end of the turning gear stub shaft 31 via the No. 3 coupling. The No. 5 support bearing 28 is sleeved on the low-pressure rotor 23, and the rear thrust bearing 29 is positioned between the No. 5 support bearing 28 and the No. 3 coupling. Other components and connection methods are the same as those of Specific Embodiment 8.

[0040] Combined with the description of specific implementation methods eight to ten, the low-pressure module of the unit is arranged symmetrically, with a total design of 2×7 levels, and adopts a new type of welded inner cylinder to meet the high-temperature adaptation requirements of the low-pressure module under extreme working conditions. The inner and outer cylinder supports are optimized, and the inner cylinder is supported on the skirt of the outer cylinder to improve the stability of the inner cylinder. The low-pressure bearing box adopts a floor-standing layout, and the shaft system has strong stability.

[0041] Specific embodiment ten: This embodiment is described in conjunction with Figures 1 to 8. The difference between this embodiment and specific embodiment nine is that the heating unit also includes a valve module, the valve module includes a medium-pressure main steam regulating combined valve A, a high-pressure main steam regulating combined valve B, a low-pressure main steam regulating combined valve C, a shut-off butterfly valve D and an adjustment butterfly valve E. The high-pressure main steam regulating combined valve B is symmetrically arranged on both sides of the high- and medium-pressure outer cylinder 8. The steam inlet of the high-pressure main steam regulating combined valve B is connected to the main steam pipeline of the boiler, and the steam outlet of the high-pressure main steam regulating combined valve B is connected to the high-pressure upper and lower steam inlets of the high- and medium-pressure outer cylinder 8 through four steam guide pipes. The medium-pressure main steam regulating combined valve A is symmetrically arranged on both sides of the high- and medium-pressure outer cylinders 8 at a certain angle. The steam inlet of the medium-pressure main steam regulating combined valve A is connected to the boiler hot recirculation pipe, and the steam outlet of the medium-pressure main steam regulating combined valve A is connected to the medium-pressure lower steam inlet cannula of the high- and medium-pressure outer cylinders 8 via two steam guide pipes. A shutoff butterfly valve D and an adjustment butterfly valve E are installed in series on the medium- and low-pressure connecting pipe 13. The low-pressure main steam regulating combined valve C is connected in parallel with the medium- and low-pressure connecting pipe 13. The steam inlet of the low-pressure main steam regulating combined valve C is connected to the front of the shutoff butterfly valve D, and the steam outlet of the low-pressure main steam regulating combined valve C is connected to the adjustment butterfly valve E. The other components and connection methods are the same as those of the ninth embodiment.

[0042] This application has been disclosed as above with preferred implementation cases, but it is not intended to limit this application. Any technician familiar with this profession can make slight changes or modifications to equivalent implementation cases using the above-disclosed structures and technical contents without departing from the scope of the technical solution of this application. However, any simple modifications, equivalent changes and modifications made to the above implementation cases based on the technical essence of this application without departing from the content of the technical solution of this application are still within the scope of the technical solution of this application.

[0043] Working principle:

[0044] The present application provides a supercritical condensing and extraction back-fired coal-fired heating unit that utilizes single intermediate reheating. Steam enters the high-pressure module through the high-pressure main steam regulating combined valve B and the high-pressure steam guide pipe. After performing work in 14 high-pressure pressure stages, it passes through the high-pressure exhaust and refrigeration, and then goes to the boiler. After single reheating, it enters the medium-pressure module through the medium-pressure main steam regulating combined valve A and the medium-pressure steam guide pipe. After performing work in 9 pressure stages, it enters the low-pressure module through the medium-low pressure connecting pipe. After performing work in 7 low-pressure electric pressure stages, it finally goes to the condenser. To meet the functional requirements of the unit's NCB mode, the present application has designed a new sliding pin system. For details, see Figure 8 of the accompanying drawings. The unit has two absolute dead points and two relative dead points. The absolute dead point of the high- and medium-pressure modules is located at the middle bearing box 16 at the rear of the high- and medium-pressure outer cylinder 8. The high- and medium-pressure outer cylinder 8 pushes the front bearing box 2 forward to expand via the front and rear centering beams 6. The absolute dead point of the low-pressure module is located at the low-pressure steam inlet centerline. The low-pressure outer cylinder 21 expands toward both ends, and the expansion is absorbed by the low-pressure end steam seal 20 with an expansion joint. The relative dead point of the high and medium pressure modules is located at the front thrust bearing 3 in the front bearing box 2, and the high and medium pressure rotors 12 expand forward and backward; the relative dead point of the low pressure module is located at the rear thrust bearing of the rear bearing box 30, and the low pressure rotor 23 expands forward and backward. The expansion of the high and medium pressure rotors and the low pressure rotors toward the middle is finally absorbed by the SSS clutch 18. In this application, the SSS clutch is a pure overrunning clutch device. When the input end speed exceeds the output end, the clutch automatically engages and transmits power. When the input end speed is lower than the output end, the clutch automatically disengages. When the SSS clutch 18 is engaged, the high and medium pressure rotors 12 and the low pressure rotor 23 of the turbine drive the generator together, and the unit can operate in pure condensing (N) or extraction condensing (C) conditions; when the low pressure cylinder steam is cut off, the low pressure rotor stops, the SSS clutch disengages, and only the high and medium pressure rotors drive the generator. All the medium pressure exhaust steam of the unit is used for extraction, and the unit operates in back pressure (B) conditions.

Claims

1. A supercritical condensing and extraction coal-fired heating unit, characterized by: The heating unit comprises a front bearing box module (2), a high- and medium-pressure module, a medium- and low-pressure connecting pipe (13), a middle bearing box module (16), a low-pressure module and a rear bearing box module (30); the front end of the rotor part in the high- and medium-pressure module is rigidly connected to the rotor of the generator (1) through the front bearing box module (2), the rear end of the rotor part in the high- and medium-pressure module is connected to the front end of the rotor part in the low-pressure module through the middle bearing box (16), the rear end of the rotor part in the low-pressure module is connected to one end of the turning gear short shaft (31) through the rear bearing box module (30), the medium- and low-pressure connecting pipe (13) is arranged between the high- and medium-pressure module and the low-pressure module, the steam inlet of the medium- and low-pressure connecting pipe (13) is connected to the medium-pressure exhaust port of the high- and medium-pressure module, and the steam outlet of the medium- and low-pressure connecting pipe (13) is connected to the steam inlet of the low-pressure module.

2. The supercritical condensing and extraction coal-fired heating unit according to claim 1, characterized in that: The front bearing box module (2) is provided with a No. 1 coupling, a front thrust bearing (3) and a No. 1 support bearing (4) inside. The front end of the rotor part in the high- and medium-pressure module is rigidly connected to the rotor of the generator (1) through the No. 1 coupling. The front thrust bearing (3) and the No. 1 support bearing (4) are mounted on the front end of the high- and medium-pressure rotor in the high- and medium-pressure module, and the front thrust bearing (3) is arranged between the No. 1 support bearing (4) and the No. 1 coupling.

3. The supercritical condensing and extraction coal-fired heating unit according to claim 2, characterized in that: The high and medium pressure module comprises high and medium pressure outer steam seals (5), a high pressure partition set (7), a high and medium pressure outer cylinder (8), a high and medium pressure bridge steam seal (9), a high and medium pressure inner cylinder (10), a medium pressure partition set (11) and a high and medium pressure rotor (12); the high and medium pressure rotor (12) is coaxially sleeved with a high pressure partition set (7), a high and medium pressure inner cylinder (10) and a high and medium pressure outer cylinder (8) in sequence from the inside to the outside, the high and medium pressure inner cylinder (10) is fixedly connected to the inner wall of the high and medium pressure outer cylinder (8), the high and medium pressure outer steam seals (5) and the medium pressure partition set (11) are respectively inserted on the inner walls of the front and rear ends of the high and medium pressure outer cylinder (8), the high and medium pressure bridge steam seal (9) is coaxially inserted on the inner wall of the middle part of the high and medium pressure inner cylinder (10), the front thrust bearing (3) and the No. 1 support bearing (4) The front thrust bearing (3) is mounted on the front end of the high and medium pressure rotor (12), and the front thrust bearing (3) is the relative expansion dead point of the high and medium pressure rotor (12) and the intermediate shaft (15) in the middle bearing module (16) in the high and medium pressure module. The generator rotor, the high and medium pressure rotor (12), and the intermediate shaft (15) expand toward the head and tail respectively with the relative dead point as the boundary. The absolute dead point of the high and medium pressure module is set at the rear of the high and medium pressure outer cylinder (8). The middle bearing box module (16) is fixedly arranged and rigidly connected to the rear of the high and medium pressure outer cylinder (8) through the high and medium pressure fixed center beam (6). The front bearing box (2) is slidingly arranged and rigidly connected to the front of the high and medium pressure outer cylinder (8) through the high and medium pressure fixed center beam (6). Relative to the absolute dead point, the high and medium pressure outer cylinder (8) pushes the front bearing (2) to expand toward the head.

4. The supercritical condensing and extraction coal-fired heating unit according to claim 3, characterized in that: A high-pressure centering beam (6) is provided between the high- and medium-pressure modules and the front bearing box module (2); one end of the high-pressure centering beam (6) is fixedly connected to the outer wall of the front bearing box module (2); and the rear end of the high-pressure centering beam (6) is fixedly connected to the outer wall of the high- and medium-pressure outer cylinder (8).

5. The supercritical condensing and extraction coal-fired heating unit according to claim 4, characterized in that: The high-pressure diaphragm set (7) comprises three high-pressure diaphragm sets, which are sequentially sleeved on the high- and medium-pressure rotors (12) along the extension direction of the high-pressure portion of the high- and medium-pressure inner cylinder (10).

6. The supercritical condensing and extraction coal-fired heating unit according to claim 5, characterized in that: The middle bearing box module (16) includes a No. 2 coupling, a No. 2 supporting bearing (14), an intermediate shaft (15), a No. 3 supporting bearing (17), an SSS clutch (18) and a No. 4 supporting bearing (19); the rear end of the high and medium pressure rotor (12) is inserted into the middle bearing box module (16) and is connected to the front end of the intermediate shaft (15) through the No. 2 coupling; the No. 2 supporting bearing (14) is arranged between the high and medium pressure rotor (12) and the housing of the middle bearing box module (16); the No. 3 supporting bearing (17) is arranged between the intermediate shaft (15) and the housing of the middle bearing box module (16); the rear end of the intermediate shaft (15) is connected to the rotor part in the low pressure module through the SSS clutch (18); and the No. 4 supporting bearing (19) is arranged between the rotor part in the low pressure module and the housing of the middle bearing box module (16).

7. The supercritical condensing and extraction coal-fired heating unit according to claim 6, characterized in that: The low-pressure module comprises a low-pressure outer cylinder (21), a low-pressure rotor (23), a low-pressure steam chamber (26), a low-pressure inner cylinder (27), two exhaust guide rings (22), two final-stage partition plates (24) and two secondary final-stage partition plates (25). The low-pressure rotor (23) is sequentially provided with a low-pressure steam chamber (26), a low-pressure inner cylinder (27) and a low-pressure outer cylinder (21) from the inside to the outside. The low-pressure inner cylinder (27) is fixedly connected to the inner wall of the low-pressure outer cylinder (21). Low-pressure front and rear steam seal bodies (20) are respectively inserted on the inner walls of the front and rear ends, a plurality of pre-twisted blades are installed on the low-pressure steam chamber (26), low-pressure positive and negative final stage partitions (24), low-pressure positive and negative secondary final stage partitions (25) and low-pressure inner cylinder heat insulation cover (26) are installed together on the inner wall of the low-pressure inner cylinder (27), a low-pressure steam inlet is provided on the upper part of the low-pressure outer cylinder (21), and the low-pressure steam inlet is connected to the medium-pressure exhaust port through a connecting pipe (13), and the front end of the low-pressure rotor (23) is equipped with a No. 4 support bearing. (19), is connected to the intermediate shaft (15) through the SSS clutch (18), the rear end of the low-pressure rotor (23) is sequentially covered with the fifth support bearing (28) and the rear thrust bearing (29), and is connected to the front end of the crankshaft (31) through the third coupling. The rear thrust bearing (29) is the relative dead point of the low-pressure rotor. The low-pressure rotor (23) and the crankshaft (31) expand toward the head and tail respectively with the relative dead point as the boundary. The low-pressure rotor ( 23) and the expansion of the high and medium pressure rotors (12), the absolute dead point of the low-pressure outer cylinder (21) is set at the low-pressure steam inlet centerline position, the low-pressure outer cylinder (21) and the low-pressure inner cylinder (27) expand toward the head and tail respectively with the absolute dead point as the boundary, the middle bearing box and the rear bearing box are fixedly arranged, and the two ends of the low-pressure front and rear steam seal bodies (20) are connected to the low-pressure outer cylinder and the middle bearing box and the rear bearing box, and the expansion joints on the low-pressure front and rear steam seal bodies (20) absorb the expansion of the low-pressure outer cylinder (21) toward the two ends.

8. The supercritical condensing and extraction coal-fired heating unit according to claim 7, characterized in that: The low-pressure module further includes two low-pressure end steam seals (20), which are respectively sleeved on one end of the low-pressure rotor (23), and the low-pressure rotor (23) is sealed with the low-pressure inner cylinder (27) through the two low-pressure end steam seals (20).

9. The supercritical condensing and extraction coal-fired heating unit according to claim 8, characterized in that: The rear bearing box module (30) includes a No. 3 coupling, a No. 5 support bearing (28) and a rear thrust bearing (29); the other end of the low-pressure rotor (23) is connected to one end of the turning gear short shaft (31) through the No. 3 coupling; and the No. 5 support bearing (28) is sleeved on the low-pressure rotor (23).

10. The supercritical condensing and extraction coal-fired heating unit according to claim 9, characterized in that: The heating unit further comprises a valve module, which comprises a medium-pressure main steam regulating combined valve (A), a high-pressure main steam regulating combined valve (B), a low-pressure main steam regulating combined valve (C), a shut-off butterfly valve (D) and an adjusting butterfly valve (E). The high-pressure main steam regulating combined valve (B) is symmetrically arranged on both sides of the high-pressure and medium-pressure outer cylinders (8). The steam inlet of the high-pressure main steam regulating combined valve (B) is connected to the main steam pipeline of the boiler. The steam outlet of the high-pressure main steam regulating combined valve (B) is connected to the high-pressure upper and lower steam inlet pipes of the high-pressure and medium-pressure outer cylinders (8) respectively through four steam guide pipes. The medium-pressure main steam regulating combined valve (A) is symmetrically arranged on both sides of the high-pressure and medium-pressure outer cylinders (8). The two sides of the high-pressure outer cylinder (8) are connected at a certain angle. The steam inlet of the medium-pressure main steam regulating combined valve (A) is connected to the boiler hot re-pipeline. The steam outlet of the medium-pressure main steam regulating combined valve (A) is connected to the medium-pressure lower steam inlet plug of the high-pressure and medium-pressure outer cylinders (8) through two steam guide pipes. A shut-off butterfly valve (D) and an adjustment butterfly valve (E) are arranged in series on the medium- and low-pressure connecting pipe (13). The low-pressure main steam regulating combined valve (C) is connected in parallel with the medium- and low-pressure connecting pipe (13). The steam inlet of the low-pressure main steam regulating combined valve (C) is connected to the front of the shut-off butterfly valve (D), and the steam outlet of the low-pressure main steam regulating combined valve (C) is connected to the adjustment butterfly valve (E).

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