WO2023168680A1

WO2023168680A1 - Full-load efficient steam turbine unit, thermodynamic system and operation method

Info

Publication number: WO2023168680A1
Application number: PCT/CN2022/080281
Authority: WO
Inventors: 王卫良; 吕俊复
Original assignee: 暨南大学; 清华大学
Priority date: 2022-03-11
Filing date: 2022-03-11
Publication date: 2023-09-14
Also published as: CN117425766A

Abstract

A full-load efficient steam turbine unit, a thermodynamic system and an operation method. At least two steam channels (7) are arranged, in a radial direction, in an adjustment stage (6) at a front end of a high-pressure cylinder (4). When the thermodynamic system is in different load intervals, the thermodynamic system can be switched to corresponding steam channels (7) for operation, and different load working conditions are adapted by using steam flow capacities, which are not exactly the same, of different steam channels (7) and matching pressure stages, the numbers of which are not exactly the same, in the different steam channels (7), thereby ensuring relatively high cycle efficiency and relatively low system energy consumption under medium and low loads. A main steam valve (5) and an adjustment valve (51) arranged in a pipeline system are used to control the on/off of each steam channel (7). A multi-stage branch steam pipe network can also be provided, such that when a switch is made between the different steam channels (7), a smooth transition can be realized, thereby avoiding a sudden change in steam flow quantity. Under the medium and low loads, a steam extraction pipeline is led out from a tail end of the adjustment stage (6) so as to be connected to an adjustable heater (19), such that the water temperature at an inlet end of a boiler (1) is increased, and the gas temperature at a denitration position is adjusted according to actual requirements, thereby meeting a denitration requirement.

Description

A full-load high-efficiency steam turbine unit, thermal system and operation method

Technical field

The invention belongs to the field of thermodynamic cycle technology, and in particular relates to a full-load high-efficiency steam turbine unit, a thermodynamic system and an operating method.

Background technique

The "dual carbon" strategy promotes the construction of a new power system with new energy as the main body. With the large-scale random fluctuations of photovoltaic, wind power and other new energy power being connected to the grid, basic power, mainly coal-fired thermal power, is forced to fully participate in in-depth adjustment. peak. The design of coal-fired thermal power units mainly considers the operating efficiency under rated load conditions. The power generation energy efficiency of the unit under medium and low load conditions during the deep peak shaving process deteriorates sharply. Compared with the rated load conditions, conventional coal-fired thermal power units 30 % rated load conditions, coal consumption increases by 30-40g/kW·h, which greatly reduces the comprehensive energy saving and emission reduction benefits of the whole society resulting from making way for new energy.

Based on the technical and structural characteristics of existing steam turbines and thermal systems, under low load conditions, whether the main steam pressure adopts sliding pressure operation, constant pressure operation, or "fixed-slip-fixed" operation, under medium and low loads, The pressure at all levels after the regulation level drops significantly. Under medium and low load conditions, the existing technology cannot effectively utilize the large ideal enthalpy drop between the rated main steam pressure that the boiler can provide and the post-regulation pressure, which directly leads to the failure of the thermal system under medium and low load conditions. The lower cycle efficiency drops significantly and the system energy consumption increases significantly.

Systematically solving the problem of reduced operating efficiency under low-load conditions during deep peak shaving of coal-fired thermal power units is key to enterprise energy conservation and consumption reduction, overall energy conservation and emission reduction, and even the completion of the national "double carbon" goal on schedule with high quality. Therefore, There is an urgent need for a steam turbine unit and thermal system that can maintain high cycle efficiency under medium and low load conditions to solve the current problems.

Contents of the invention

In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a full-load high-efficiency steam turbine unit, a thermal system and an operating method, which are mainly used to solve the problem of medium and low-level coal-fired thermal power units in the existing technology when participating in the deep peak-shaving process. Problems such as low operating efficiency and poor adjustment ability under load.

In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

In a first aspect, the present invention provides a full-load high-efficiency steam turbine unit, which includes a power cylinder, which is any one of a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder. The power cylinder is provided with a regulating stage. , the regulating stage is provided with at least two steam channels along the radial direction, the front end of the steam channel is connected with at least one regulating valve for controlling the steam flow on and off, and at least one pressure stage is provided in at least one of the steam channels, each Each of the pressure stages is composed of a stationary blade cascade located at the front end and a moving blade cascade located at the rear end.

Furthermore, there is at least one steam channel that does not have a stationary blade cascade or a stationary blade cascade with a constant axial flow area, and at the same time there is no moving blade cascade or a non-reactive moving blade cascade.

Further, at least one pair of stationary blade cascades in adjacent steam passages are connected in the radial direction. The radially connected stationary blade cascades are defined as a stationary blade cascade pair, and the stationary blade cascade pairs form a pair of stationary blade cascades at the connection point. An annular stationary blade isolation zone extending in the circumferential direction, the annular stationary blade isolation zone is connected to the end of the partition wall between adjacent steam channels.

Further, the stator cascade extends directly to the innermost steam channel or extends to the innermost steam channel through a partition, and the partition has a first steam vent in the circulation area corresponding to each steam channel.

Further, there is at least one pair of moving blade cascades in adjacent steam passages that are connected in the radial direction. The radially connected moving blade cascades are defined as a moving blade cascade pair, and the moving blade cascade pairs form a moving blade cascade at the connection point. An annular moving blade isolation zone extending in the circumferential direction.

Further, one of the moving blade cascades near the inner side of the pair of moving blades is directly fixed on the hub of the steam turbine unit or fixed on the hub of the steam turbine unit through a wheel disk, and the wheel disk is in a position corresponding to each A second steam vent is provided in the circulation area of the steam channel.

Further, there is a fitting gap between the annular moving blade cascade isolation zone and the annular stationary blade cascade isolation zone or the end of the partition wall, and a radial steam seal assembly is provided in the fitting gap.

Further, the number of pressure levels in any one of the steam channels is no less than the number of pressure levels in any one of the steam channels located outside it.

Further, the steam flow capacity of the steam channel gradually decreases from the outside to the inside.

Further, at least one of the steam channels adopts a circumferential steam intake method.

In a second aspect, the present invention provides a full-load high-efficiency thermal system, including a boiler and the above-mentioned full-load high-efficiency steam turbine unit. The power cylinder is a high-pressure cylinder, and the boiler is connected to the steam channel through a piping system. In one connection, the pipeline system is provided with a main steam valve for controlling the main steam flow of the boiler, and at least one regulating valve is provided between the main steam valve and each of the steam channels.

Further, the pipeline system includes a main steam pipeline and at least one branch steam pipeline network, the main steam valve is located on the main steam pipeline, and the branch steam pipeline network is composed of several branch steam pipes. Each bronchial tube is provided with a regulating valve.

Further, it also includes a heat recovery system, the heat recovery system includes an adjustable heater, the adjustment stage is connected to the adjustable heater through an air extraction pipeline, and the air extraction pipeline is provided with an air regulating valve assembly. The adjustable heater is connected to the boiler.

In a third aspect, the present invention provides an operating method for a full-load high-efficiency thermal system, which includes the following steps: sorting the steam passages from large to small according to the steam flow capacity of each steam channel, and sequentially determining the first steam channel, the second steam channel, and the second steam channel. Channel...nth steam channel;

Divide the operating load of the thermal system into m load intervals, and each load interval corresponds to one or more steam channels;

According to the current operating load rate of the thermal system or according to the set target load rate, determine the target load interval that the thermal system needs to enter, and switch to the steam channel corresponding to the target load interval.

Further, when the load of the thermal system is increased, the final steam channel to be switched to is determined according to the load increase rate or the target load rate requirement;

Open the final steam channel directly, or;

If there are other intermediate steam channels between the final steam channel and the current steam channel, the intermediate steam channels are opened sequentially starting from the current steam channel or simultaneously, until the final steam channel is opened;

Determine whether the current load reaches the set value. If it does, gradually close other steam channels except the final steam channel.

Further, when the load of the thermal system is reduced, the final steam channel to be switched is determined according to the load reduction rate requirement;

Gradually close the regulating valve corresponding to the current steam channel;

Determine whether the current load reaches the set value. If it does, gradually open the regulating valve corresponding to the final steam channel and close the regulating valve corresponding to the current steam channel.

Further, when the load rate of the thermal system is lower than X% of the rated load, the gas regulating valve assembly is opened to input the steam in the regulating stage into the adjustable heater.

Further, the temperature of the boiler flue is detected. If the temperature of the boiler flue is lower than the set temperature value, the gas regulating valve assembly is opened, and the boiler flue is adjusted by controlling the opening of the gas regulating valve assembly. temperature to be higher than the set temperature value.

Compared with the prior art, the present invention at least includes the following beneficial effects:

At least two steam channels are provided along the radial direction in the regulating stage at the front end of the high-pressure cylinder. When the thermal system is in different load ranges, it can be switched to the corresponding steam channel operation to utilize the different steam flow capabilities between different steam channels. It is equipped with different numbers of pressure levels to adapt to different load conditions and ensure higher cycle efficiency and lower system energy consumption under medium and low loads;

The main steam valve and regulating valve set in the piping system are used to control the on and off of each steam channel. A multi-stage branch steam pipe network can also be set up to achieve a smooth transition when switching between different steam channels and avoid steam flow. produce mutations;

Under medium and low loads, the temperature of the boiler flue is low, and there is a risk of not meeting the denitrification demand. By leading an exhaust pipe at the end of the regulating stage and connecting it to an adjustable heater, the water temperature at the inlet of the boiler is increased, and the denitrification point is adjusted according to actual needs. flue temperature to meet denitrification requirements.

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Description of the drawings

The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without exerting creative efforts, other embodiments can be obtained based on the following drawings. Picture attached.

Figure 1 is a schematic half-section view of a full-load high-efficiency steam turbine unit of the present invention.

Figure 2 is an overall schematic diagram of a full-load high-efficiency thermal system of the present invention.

Figure 3 is a schematic diagram of a piping system in one embodiment.

Figure 4 is a schematic diagram of a piping system in another embodiment.

Detailed ways

The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limitations of the invention. Furthermore, the terms “first”, “second” and “third” are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, when a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first device or the second device. When a specific device is described as being connected to another device, the specific device may be directly connected to the other device without an intervening device, or may not be directly connected to the other device but with an intervening device.

Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered a part of the specification.

In the first aspect, referring to Figure 1 , this embodiment discloses a full-load high-efficiency steam turbine unit, which includes a power cylinder 2. The power cylinder 2 is any one of a high-pressure cylinder 4, a medium-pressure cylinder, and a low-pressure cylinder. The cylinder 2 is provided with a regulating stage 6. The regulating stage 6 is provided with at least two steam channels 7 along the radial direction. The front end of the steam channel 7 is connected with at least one regulating valve 51 for controlling the on-off steam flow. In the at least one steam channel 7 There is at least one pressure stage. Each pressure stage is composed of a stationary blade cascade 8 located at the front end and a moving blade cascade 9 located at the rear end. The stationary blade cascade 8 is composed of a plurality of stationary blades arranged in the circumferential direction. The moving blade cascade 9 is composed of It is composed of multiple moving blades arranged in the circumferential direction, and forms a pressure stage through two stationary blade cascades 8 and moving blade cascades 9 in tandem. The pressure stage performs work in response to the main steam generated from the boiler 1.

It should be noted that the power cylinder in the steam turbine unit can be a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder, and the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder can each be provided with a regulating stage with a steam channel. Therefore, it should be considered that regardless of Which one or more power cylinders are equipped with a regulating stage with a steam channel is within the scope of protection claimed by this embodiment, and will not be described one by one here.

Each steam channel 7 has a corresponding regulating valve 51 that controls the on-off steam flow. It should be noted that one regulating valve 51 can control one steam channel 7, or one regulating valve 51 can control two or more. The steam channel 7 can also be controlled by multiple regulating valves 51, or it can be a comprehensive application of the above methods.

Furthermore, each steam channel 7 has at least two configuration parameters, namely the flow area of the steam channel 7 and the number of pressure levels set in the steam channel 7. The flow area of each steam channel 7 can be the same or different. , the number of pressure levels set in each steam channel 7 can also be the same or different. Under medium and low load conditions, the inlet of regulating stage 6 is close to the rated main steam pressure, and the pressure of all stages after regulating stage 6 drops significantly. Therefore, a large ideal enthalpy drop is formed at the inlet and outlet of regulating stage 6. , in order to improve the cycle efficiency under medium and low load conditions, it is necessary to utilize the enthalpy drop in the area of regulation stage 6 as much as possible. Therefore, different steam channels 7 are configured to have technical states with different enthalpy drop processing capabilities. This There are many ways to adjust, such as changing the number of pressure stages of each steam channel 7 while ensuring the same flow area of each steam channel 7, or changing the number of pressure stages of each steam channel 7 while ensuring the same. The flow area of each steam channel 7, or the number of pressure levels and the flow area of the steam channel 7 can be changed at the same time, so that one or more steam channels 7 are more suitable for operation in a specific load range. It should be noted that in a certain Under a specific load, one steam channel 7 can be connected, or multiple steam channels 7 can be connected, which is not limited here.

In this embodiment, the steam channel 7 closer to the internal axis has more pressure levels. When the load condition changes, the corresponding steam channel 7 can be switched by controlling the regulating valve 51. That is, the lower the load, the more pressure levels. To the steam channel 7 with more pressure levels, the enthalpy drop under medium and low load conditions can be fully utilized to improve cycle efficiency and reduce system energy consumption.

Of course, in the multiple steam channels 7 , in addition to setting different numbers of pressure stages, different flow areas can also be set to increase the pressure at the outlet of the regulating stage 6 and increase the air inlet pressure of the high-pressure cylinder 4 .

In some embodiments, there is at least one steam channel 7 that does not have a static blade cascade 8 or a static blade cascade 8 with a constant axial flow area, and at the same time, there is no moving blade cascade 9 or a non-reactive moving blade. Gate 9, that is, there is no pressure level that can do work in such a steam channel 7. The purpose of this design is that when the unit is operating under full/high load conditions, there is no need for the adjustment stage 6 to participate in the adjustment work, and the The main steam flows into the high-pressure cylinder 4 to perform work to improve operating efficiency under full/high load conditions.

In some embodiments, partition walls are provided between adjacent steam channels 7. The partition walls can prevent gas blow-by between different steam channels 7, and the closer the partition wall is to the inside, the shorter the extension distance along the steam flow direction is. , there is a step difference between two adjacent partition walls; there is at least one pair of stationary blade cascades 8 in adjacent steam channels 7 that are connected in the radial direction, and the radially connected stationary blade cascades 8 are defined as a stationary blade cascade pair, A stationary blade cascade pair spans two steam channels 7 at the same time. The stationary blade cascade pair forms an annular stationary blade cascade isolation zone 10 extending in the circumferential direction at the connection of the two stationary blade cascades 8. The annular stationary blade cascade isolation zone 10 For isolating the steam in different steam channels 7, the annular stator blade isolation strip 10 is connected to the end of the corresponding partition wall. Since the stator blades are stationary, in order to improve the fixing strength of the stator blades in the case of steam impact, the stator blades are connected to the end of the corresponding partition wall. At the step difference between two adjacent partition walls, two radially adjacent stationary blade cascades 8 are connected through an annular stationary blade cascade isolation belt 10, and then the annular stationary blade cascade isolation belt 10 is fixed at the corresponding partition wall. It should be understood that the annular stationary blade cascade isolation strip 10 can be a part of the end structure of the partition wall, or it can be another component that connects the two stationary blade cascades 8 in the upper and lower radial directions at the same time, and Connect the ends of the partition walls in the axial direction. Furthermore, each steam channel 7 is opened in the inner cylinder 11 of the steam turbine, and a plurality of partition walls are formed in the inner cylinder 11 of the steam turbine. The annular static blade isolation belt 10 is also fixed on the inner cylinder 11 of the steam turbine.

As an implementation method, the stator cascade 8 in the innermost steam channel can directly extend into the innermost steam channel 7; except for the innermost steam channel, if there is only one pressure level in the remaining steam channels, Then the stationary blade cascade of this pressure stage and the stationary blade cascade of the last pressure stage in the innermost steam channel form a stationary blade cascade pair; if there are multiple pressure levels in the remaining steam channels, except for the first pressure stage, from The stator cascades of the second and subsequent pressure stages can be extended to the innermost steam channel 7 through the partition 16. The partition 16 ensures the stability of the bottom of the stator cascade 8, and at the same time, the partition 16 corresponds to each A first steam vent is provided in the circulation area of the steam channel 7 to facilitate the circulation of steam. The function of this first steam vent is only for ventilation and does not have the function of doing work; of course, from the second stage and subsequent pressure levels The stationary blade cascade can be a single stationary blade cascade, or it can form a stationary blade cascade with the stationary blade cascades of the adjacent steam channels. Of course, it is also not necessary to connect the partition 16, and the stationary blade cascade body can be extended or not. . In the embodiment where the stator cascade extends directly or extends through a partition to the innermost steam channel 7, a steam seal can be provided at the bottom of the stator cascade 8 or the partition 16 to ensure the seal between it and the turbine hub 13; Similarly, at the connection between the stationary blade cascade 8 and the partition plate 16, there is a corresponding annular moving blade cascade isolation zone 14 or wheel disc 12 in space, so a steam seal assembly must also be provided in the moving and stationary gaps.

Furthermore, the radial projections of the two stationary blade cascades 8 constituting a stationary blade cascade pair overlap with each other, and the two stationary blade cascades 8 have the same shape, because it is considered that as the unit load changes, when switching the steam channel 7 , often switches from one stationary vane pair to the other. In order to ensure smooth switching and reduce the impact of unit vibration, noise and other effects caused by changes in load and/or pressure level number and/or flow area, the static blade cascade is The two stationary blade cascades 8 on the blade cascade pair are designed in the same shape.

In some embodiments, there is at least one pair of moving blade cascades 9 in adjacent steam channels 7 that are connected in the radial direction. The radially connected moving blade cascades 9 are defined as a moving blade cascade pair, and a moving blade cascade pair is horizontally connected at the same time. Across the two steam channels 7, the moving blade cascade pair forms an annular moving blade cascade isolation zone 14 extending in the circumferential direction at the connection of the two movable blade cascades 9. The annular moving blade cascade isolation zone 14 is used to connect the upper and lower moving blade cascades. The cascade 9 not only has the function of strengthening the connection strength, but also has the function of isolating the steam in different steam channels 7 .

As an implementation method, for the innermost moving blade cascade pair, the moving blade cascade 9 near the inner side is directly fixed on the hub 13 of the steam turbine unit 2; while for the remaining moving blade cascade pairs, the moving blade 9 near the inner side is directly fixed on the hub 13 of the steam turbine unit 2. The grid 9 is fixed on the hub 13 of the steam turbine unit 2 through the wheel disc 12. The wheel disc 12 is provided with a fixed groove, and the inner moving blade grid 9 is fixed in this fixed groove. The wheel disc 12 serves as a force transmission to move the moving blades. The grid 9 is connected to the hub 13. Secondly, the wheel plate 12 is provided with a second steam vent 17 in the circulation area corresponding to each steam channel 7. The size and opening of the second steam vent 17 and the first steam vent are Corresponding position can also play a role in circulating steam.

Similarly, and further, the radial projections of the two moving blade cascades 9 constituting a moving blade cascade pair overlap with each other. The arrangement principle is the same as that of the stationary blade cascade 8 and will not be described again here.

As an embodiment, the stationary blade cascade 8 and the moving blade cascade 9 that form a pressure stage belong to the stationary blade cascade pair and the moving blade cascade pair respectively spanning the same steam channel 7. Since the stationary blade cascade pair and the moving blade cascade pair belong to will span at least two steam channels 7 at the same time, and the pressure stage consists of a stationary blade cascade 8 at the front end and a moving blade cascade 9 at the rear end. Therefore, the stationary blade cascade pair and the moving blade cascade pair are located in the same steam The stationary blade cascade 8 and the moving blade cascade 9 in the channel 7 form a pressure stage under the condition that the stationary blade cascade 8 is in front and the moving blade cascade 9 is in the rear, avoiding the need for stator blades crossing different steam channels 7 The stationary blade cascade 8 and the movable blade cascade 9 located in the same steam channel 7 form a pressure stage to avoid possible unbalanced operation and influence on adjacent steam channels 7 and other hidden dangers during the operation of the pressure stage.

In this embodiment, there is a fitting gap between the annular moving blade cascade isolation zone 14 and the annular stationary blade cascade isolation zone 10 or the end of the partition wall, and a radial steam seal assembly 15 is provided in the fitting gap, which means that the annular stationary blade cascade is The isolation zone 10 and the end of the partition wall are both stationary structural components. Regardless of the connection relationship between the annular stationary blade isolation zone 10 and the end of the partition wall, there is no connection between the annular moving blade isolation zone 14 and at least one structural component therein. There are matching gaps between them. In order to prevent the steam between different steam channels 7 from channeling each other and affecting the normal flow of air flow in the corresponding flow channels, a radial steam seal assembly 15 is provided in the matching gaps to realize the annular moving blade isolation zone 14 Sealed connection with the annular stationary blade isolation belt 10 or the end of the partition wall.

In this embodiment, the number of pressure levels in any steam channel 7 is no less than the number of pressure levels in any steam channel 7 located outside it. Preferably, from outside to inside, the number of pressure levels in the steam channel 7 is Increasing relationship, for example, four steam channels 7 are arranged sequentially from outside to inside. The outermost steam channel 7 is not set with a pressure level, the second outer steam channel 7 is set with one pressure level, the second inner steam channel 7 is set with two pressure levels, and the innermost steam channel 7 is set with two pressure levels. The steam channel 7 is provided with three pressure levels. Furthermore, in the last pressure level of the innermost steam channel 7, the stationary blade cascade pair and the movable blade cascade pair respectively belonging to the stationary blade cascade 8 and the moving blade cascade 9 are also in the sub-inner steam. In the passage 7, and the stationary blade cascade pair and the moving blade cascade pair, the other stationary blade cascades 8 and the moving blade cascades 9 constitute the first pressure stage in the sub-inner steam channel 7, and the conditions of the other steam channels 7 and pressure levels can be Refer to Figure 1.

As an embodiment, the steam flow capacity of the steam channel 7 gradually decreases from the outside to the inside; as another embodiment, the steam flow capacity of the steam channels 7 can also be all the same.

Preferably, there is at least one steam channel 7 adopting a circumferential steam intake method.

In the second aspect, referring to Figure 2, this embodiment provides a full-load high-efficiency thermal system, including a boiler 1 and a full-load high-efficiency steam turbine unit in the above embodiment, in which the power cylinder 2 is a high-pressure cylinder 4, and the boiler 1 The pipeline system is connected to the steam channels 7 one by one. The pipeline system is provided with a main steam valve 5 for controlling the main steam flow of the boiler 1. There is at least one regulator between the main steam valve 5 and each steam channel 7. The valve 51 and the main steam valve 5 are used to control the on-off of the main steam at the outlet of the boiler 1, while the regulating valve 51 is used to control the on-off of one or more steam channels 7. Of course, adjustments that can control the flow ratio can also be adopted. The valve 51 changes the steam flow rate by controlling and adjusting the opening of the valve 51.

It should be noted that in order to realize the operation switching between the steam channels 7, there are many corresponding relationships between the regulating valve 51 and the steam channel 7. These corresponding relationships are all realized by the pipeline system. In more detail, the pipeline system includes a There is a main steam pipeline and at least one branch steam pipeline network. The main steam valve 5 is located on the main steam pipeline. The branch steam pipeline network is composed of several branch pipes, and a regulating valve 51 is provided on each branch pipe.

Referring to Figure 3, as an implementation method, a one-point-multiple approach is adopted. One main steam pipe is matched with a first-level branch steam pipe network. There are as many branch pipes as there are steam channels 7, and one regulating valve 51 directly controls one. Steam channel 7, there is only one regulating valve 51 between steam channel 7 and main steam valve 5;

Referring to Figure 4, as another implementation method, one main steam pipeline is matched with a two-level branch steam pipe network, that is, the main steam pipeline is directly connected to the first-level branch steam pipe network, and the first-level branch steam pipe network is directly connected. The first-level branch steam pipe network is directly connected to the second-level branch steam pipe network. In the embodiment with four steam channels 7, the first-level branch steam pipe network has three branch steam pipes, and the second-level branch steam pipe network has three branch steam pipes. There are four branch pipes. Each branch pipe in the first-level branch steam pipe network is connected to two branch pipes in the second-level branch steam pipe network. The advantage of this setting is that when it is necessary to switch and adjust across the steam channel 7 At this time, the steam channel 7 in the middle can play a transitional role, and there is a transitional stage.

In addition, if the power cylinder 2 is a medium-pressure cylinder, and a regulating stage with a steam channel is provided in the medium-pressure cylinder, then this regulating stage is connected to the regenerated pipeline in the boiler. Similarly, the regenerated pipe The connection relationship between the pipeline and the regulating stage of the medium-pressure cylinder can refer to the connection relationship between the boiler main steam pipeline and the regulating stage of the high-pressure cylinder mentioned above. The same is true if the power cylinder 2 is a low-pressure cylinder, so we will not go into detail here. Repeat.

Referring to Figure 2, in some embodiments, a heat recovery system 3 is also included. The heat recovery system 3 includes an adjustable heater 19. The end of the adjustment stage 6 is connected to the adjustable heater 19 through an exhaust pipe, usually at each After the pressure level of the steam channel 7 is connected to the air extraction pipeline, the air extraction pipeline is provided with a gas regulating valve assembly 18. The gas regulating valve assembly 18 can adjust the on-off and circulation of the gas pumping pipe, and the adjustable heater 19 is connected to the boiler 1 , this purpose is that when it is under medium and low load, the flue temperature of boiler 1 is low, and there is a risk of not meeting the denitrification demand. By leading an exhaust pipe at the end of regulating stage 6 and connecting it to the adjustable heater 19, it can improve The water temperature at the inlet of boiler 1 is adjusted according to actual needs, and the smoke temperature at the denitrification point is adjusted to meet denitrification requirements.

In the third aspect, this embodiment provides a method for operating a full-load high-efficiency thermal system, including the following steps:

S1: Sort from large to small according to the steam flow capacity of each steam channel 7, and determine the first steam channel, the second steam channel... the nth steam channel in order; it should be noted that the steam flow capacity can be based on the steam flow capacity. It can be defined by the flow area of channel 7, or it can be defined based on the number of pressure levels in steam channel 7. Of course, it can also be defined based on a combination of the above two, or other situations. In short, the purpose of this sorting is to plan each in advance. Steam channel 7 classifies the steam processing capacity to adapt to operating conditions under different loads;

S2: Divide the operating load of the thermal system into m load intervals, and each load interval corresponds to one or more steam channels 7; it should be noted that the number of load intervals can be the same as the number of steam channels 7. This In this case, there may be a one-to-one correspondence between one load interval and one steam channel 7, or there may be a situation where one load interval corresponds to at least one steam channel 7; of course, the number of load intervals may also be different from the number of steam channels 7. Similarly, correspondingly, there are also situations where multiple load intervals are bound to the steam channel 7;

In this embodiment, n=4, that is, four steam channels 7 are arranged in sequence from the outside to the inside. There is no stationary blade cascade 8 in the outermost steam channel or a stationary blade cascade 8 with a constant axial flow area. At the same time, there is no moving blade cascade 9 or no reaction-free moving blade cascade 9. The steam flow capacity of this steam channel is considered to be infinite, so the steam flow capacity of the outermost steam channel is the largest and is defined as the first steam. channel; while the sub-outer steam channel is set with one pressure level, the sub-inner steam channel is set with two pressure levels, and the innermost steam channel is set with three pressure levels, because when the steam channel 7 contains one or more pressure levels at the same time, in this Under the condition that the regulating valve 51 of the steam channel 7 is fully open, the main steam parameter after the main steam valve 5 is used as the rated parameter as the inlet condition of the steam channel 7, and the back pressure of the steam channel 7 is adjusted. When one of the pressure levels reaches the critical state, the flow rate The maximum flow rate, according to which the flow capacities of the remaining three steam channels are sorted from large to small, and the steam channels from outside to inside are defined as the second steam channel, the third steam channel and the fourth steam channel respectively; In addition, as an implementation method, the throat area of each pressure stage nozzle is the same, so the flow capacity of the innermost three stages is the smallest, and the flow capacity of the outward steam channels increases in sequence.

In more detail, four load intervals are also set, that is, m=n=4, which are [100%, 80%], [80%, 60%], [60%, 40%] and [40%, 20 %], [100%, 80%] load interval corresponds to the first steam channel, [80%, 60%] load interval corresponds to the second steam channel, [60%, 40%] load interval corresponds to the third steam channel, [40 %, 20%] load interval corresponds to the fourth steam channel;

S3: According to the current operating load rate of the thermal system, or according to the set target load rate, determine the target load interval that the thermal system needs to enter, and switch to the steam channel corresponding to the target load interval. If the load interval does not change, then Keep the current steam channel running. If the load interval changes, switch from the current steam channel to the steam channel corresponding to the target load interval.

It can be seen that as the load of the unit changes, the corresponding most suitable steam flow capacity also changes. By automatically reconstructing the thermal system state and switching to different steam channels or steam channel groups, the reconstruction The final steam flow capacity better matches the current load rate. In order to achieve this goal, there are many ways to combine the load interval and the steam channel. The most basic one is that one load interval corresponds to one steam channel. Of course, it can also be one load interval. Corresponds to two or more steam channels. The reason for switching the steam channel can be passive or active, that is, when the unit load changes, the steam channel can be switched accordingly; it can also be to artificially set a target load rate, and other devices in the thermal system While adjusting, the steam channel 7 is also actively switching.

In some embodiments, when the load of the thermal system increases, the final steam channel to be switched is determined according to the load increase rate or the target load rate requirement; it should be noted that whether the steam channel 7 is switched actively or passively, as long as When the trigger condition for switching steam channel 7 is met, a parameter for the load increase rate or target load rate requirement will be generated, such as whether it is necessary to switch from the fourth steam channel to the second steam channel or to the third steam channel, which will form a final steam passage;

After the final steam channel is determined, the final steam channel can be opened directly. This method is to increase the load adjustment rate. After directly opening the final steam channel, it can be stabilized through other factors. This method is a static adjustment method;

Or this method can be adopted, that is, if there are other intermediate steam channels between the final steam channel and the current steam channel, the intermediate steam channels will be opened sequentially starting from the current steam channel or at the same time, until the final steam channel is opened; that is, if necessary When switching from the fourth steam channel to the second steam channel, there is a third steam channel between the two. During the switching process, the third steam channel needs to be opened first to serve as a transition, and finally the second steam channel is opened. ; It can be seen that this method is a dynamic adjustment method, and the opening status of each steam channel will change during the load increase process;

During the process of switching steam channels, it is judged whether the current load reaches the set value. If it reaches the set value and the load is stabilized by adjusting boiler 1, the steam channels will no longer be opened downwards and other steam channels except the final steam channel will be gradually closed. , that is, first close the fourth steam channel, and then close the third steam channel. It should be noted that when gradually closing other steam channels except the final steam channel, the steam channels should be closed in order from small to large in steam flow capacity. Of course, It can also be closed at the same time, but it needs to be closed slowly during the closing process. In addition, if it occurs during the dynamic adjustment process, such as switching from the fourth steam channel to the second steam channel, when the third steam channel is opened and the load has reached the set value, it will stay in the third steam channel and no longer To open the second steam channel, it can be seen that in some embodiments, whether the current load reaches the set value is used as the first determination priority for adjusting the opening of the steam channel.

In addition, when it is in the transition stage, that is, when the third steam channel is opened, a certain proportion of the third steam channel can be opened first, and a certain proportion of the fourth steam channel can be closed. When the third steam channel is opened to a set proportion or when the fourth The steam channel is closed to a certain ratio, and then the second steam channel is opened. The sum of the opening degrees of the three steam channels can be controlled according to a certain functional relationship or a certain value, and finally the second steam channel is fully opened, and the fourth steam is closed. channel and a third steam channel.

In some embodiments, when the load of the thermal system is reduced, the final steam channel to be switched is determined according to the load reduction rate requirement; it should be noted that, whether the steam channel is actively or passively switched, as long as the switching steam channel 7 is met The trigger condition will generate a load reduction rate requirement parameter, such as whether it is necessary to switch from the second steam channel to the third steam channel or to the fourth steam channel, which will form a final steam channel;

Gradually close the regulating valve 51 corresponding to the current steam channel;

Determine whether the current load reaches the set value. If it does, and the load is stabilized by adjusting the boiler 1, then gradually open the regulating valve 51 corresponding to the final steam channel, and close the regulating valve 51 corresponding to the current steam channel.

In more detail, if you need to switch from the second steam channel to the fourth steam channel, first, gradually close the regulating valve 51 of the second channel according to the load reduction rate required by the dispatch. When the load reaches the set value, While stabilizing the load by adjusting boiler 1, gradually open the regulating valve 51 of the fourth steam channel, and slowly close the regulating valve 51 of the second steam channel.

In some embodiments, when the load rate of the thermal system is lower than X% of the rated load, the gas regulating valve assembly 18 is opened to input the steam in the regulating stage 6 into the adjustable heater 19, where 20% < x% <60%. Preferably, according to system optimization, conventional subcritical units can determine x% to be about 40% through calculation verification. That is, when the unit load rate is lower than the set value, the steam in the regulation stage 6 needs to be returned to the adjustable heater 19 and then flow back to the boiler 1.

In some embodiments, the flue temperature of the boiler 1 is detected. If the flue temperature of the boiler 1 is lower than the set temperature value, the gas regulating valve assembly 18 is opened. By controlling the opening of the gas regulating valve assembly 18, the regulation level 6 is adjusted. The amount of return steam extracted from the boiler is adjusted to adjust the temperature of the flue of boiler 1 to be higher than the set temperature value.

In summary, compared with the existing technology, the above embodiments provide a full-load high-efficiency steam turbine unit, a thermal system and an operating method. At least two steam channels 7 are provided radially in the regulating stage 6 at the front end of the high-pressure cylinder 4. When the thermal power When the system is in different load ranges, it can be switched to the corresponding steam channel 7 for operation, and the different steam flow capacities between different steam channels 7 and the different numbers of pressure levels provided in them can be used to adapt to different loads. working conditions to ensure higher cycle efficiency and lower system energy consumption under medium and low loads;

The main steam valve 5 and the regulating valve 51 set in the pipeline system are used to control the on-off of each steam channel 7. A multi-stage branch steam pipe network can also be set up to achieve a smooth transition when switching between different steam channels 7. Avoid sudden changes in steam flow;

Under medium and low loads, the temperature of the flue of boiler 1 is low, and there is a risk of not meeting the denitrification demand. By leading an air extraction pipe at the end of regulation stage 6 and connecting it to the adjustable heater 19, the water temperature at the inlet end of boiler 1 is increased. According to the actual situation The smoke temperature at the denitrification point needs to be adjusted to meet the denitrification requirements.

The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art on the basis of the present invention fall within the scope of the present invention. Scope of protection claimed.

Claims

A full-load high-efficiency steam turbine unit, including a power cylinder, which is any one of a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder. The power cylinder is provided with an adjustment stage, and is characterized in that: The regulating stage is provided with at least two steam channels along the radial direction, and the front end of the steam channel is connected with at least one regulating valve for controlling the steam flow on and off. At least one pressure stage is provided in at least one of the steam channels, and each of the steam channels is The pressure stage consists of a stationary blade cascade located at the front end and a moving blade cascade located at the rear end.
A full-load high-efficiency steam turbine unit according to claim 1, characterized in that there is no stationary blade cascade or a stationary blade cascade with a constant axial flow area in at least one of the steam channels. Moving blade cascade or a moving blade cascade with no reaction degree.
A full-load high-efficiency steam turbine unit according to claim 1, characterized in that there is at least one pair of stationary blade cascades in adjacent steam passages connected in the radial direction, defining the radially connected stationary blade cascades. It is a pair of stationary blades. The pair of stationary blades forms an annular isolation zone extending along the circumferential direction at the connection point. The annular isolation zone of the stationary blades is connected to the end of the partition wall between adjacent steam channels. .
A full-load high-efficiency steam turbine unit according to claim 1, characterized in that the stationary blade cascade extends directly to the innermost steam channel or extends to the innermost steam channel through a partition plate, and the partition plate is in a position corresponding to each A first steam vent is provided in the circulation area of the steam channel.
A full-load high-efficiency steam turbine unit according to claim 3, characterized in that there is at least one pair of movable blade cascades in adjacent steam passages connected in the radial direction, defining the radially connected movable blade cascades. It is a moving blade cascade pair, and the moving blade cascade pair forms an annular moving blade cascade isolation zone extending along the circumferential direction at the connection point.
A full-load high-efficiency steam turbine unit according to claim 5, characterized in that one of the moving blade cascades on the inner side of the pair of moving blade cascades is directly fixed on the hub of the steam turbine unit or fixed through a wheel disc. On the hub of the steam turbine unit, the wheel disc is provided with a second steam vent in the circulation area corresponding to each steam channel.
A full-load high-efficiency steam turbine unit according to claim 6, characterized in that there is a matching gap between the annular moving blade cascade isolation zone and the annular stationary blade cascade isolation zone or the end of the partition wall, and the matching gap There is a radial steam seal component in it.
A full-load high-efficiency steam turbine unit according to claim 1, characterized in that the number of pressure stages in any one of the steam channels is no less than the number of pressure stages in any of the steam channels located outside it.
A full-load high-efficiency steam turbine unit according to claim 2, characterized in that the steam flow capacity of the steam channel gradually decreases from the outside to the inside.
A full-load high-efficiency steam turbine unit according to any one of claims 1 to 9, characterized in that at least one of the steam channels adopts a circumferential steam intake method.
A full-load high-efficiency thermal system, characterized in that it includes a boiler and a full-load high-efficiency steam turbine unit according to any one of claims 1 to 10, the power cylinder is a high-pressure cylinder, and the boiler passes through a pipeline The system is connected to the steam channels one by one. The pipeline system is provided with a main steam valve for controlling the main steam flow of the boiler. There is at least one between the main steam valve and each of the steam channels. A regulating valve.
A full-load high-efficiency thermal system according to claim 11, characterized in that the pipeline system includes a main steam pipeline and at least one level of branch steam pipe network, and the main steam valve is located on the main steam pipe. On the pipeline, the steam branch pipe network is composed of several bronchial pipes, and each of the bronchial pipes is provided with a regulating valve.
A full-load high-efficiency thermal system according to claim 12, characterized in that it also includes a heat recovery system, the heat recovery system includes an adjustable heater, and the adjustment stage is connected to the adjustable heater through an exhaust pipe. The heater is connected, the air extraction pipe is provided with a gas regulating valve assembly, and the adjustable heater is connected to the boiler.
An operation method for a full-load high-efficiency thermal system, which is characterized by including the following steps:

Sort from large to small according to the steam flow capacity of each steam channel, and determine the first steam channel, the second steam channel...the nth steam channel in order;

Divide the operating load of the thermal system into m load intervals, and each load interval corresponds to one or more steam channels;

According to the current operating load rate of the thermal system or according to the set target load rate, determine the target load interval that the thermal system needs to enter, and switch to the steam channel corresponding to the target load interval.
A method of operating a full-load high-efficiency thermal system according to claim 14, characterized in that:

When the load of the thermal system is increased, the final steam channel to be switched is determined according to the load increase rate or the target load rate requirement;

Open the final steam channel directly, or;

If there are other intermediate steam channels between the final steam channel and the current steam channel, the intermediate steam channels are opened sequentially starting from the current steam channel or simultaneously, until the final steam channel is opened;

Determine whether the current load reaches the set value. If it does, gradually close other steam channels except the final steam channel.
A method of operating a full-load high-efficiency thermal system according to claim 15, characterized in that:

When the load of the thermal system is reduced, the final steam channel to be switched to is determined according to the load reduction rate requirement;

Gradually close the regulating valve corresponding to the current steam channel;

Determine whether the current load reaches the set value. If it does, gradually open the regulating valve corresponding to the final steam channel and close the regulating valve corresponding to the current steam channel.
The operating method of a full-load high-efficiency thermal system according to any one of claims 14 to 16, characterized in that when the load rate of the thermal system is lower than X% of the rated load, the air regulating valve assembly is opened, Steam from the regulation stage is fed into the adjustable heater.
The operation method of a full-load high-efficiency thermal system according to any one of claims 14 to 16, characterized in that the boiler flue temperature is detected, and if the boiler flue temperature is lower than the set temperature value, the said boiler flue temperature is opened. The gas regulating valve assembly adjusts the boiler flue temperature to be higher than the set temperature value by controlling the opening of the gas regulating valve assembly.