阅读说明：本技术 一种多源一体自动切换的联合供汽系统和方法 (Multi-source integrated automatic switching combined steam supply system and method ) 是由 郑天帅 余小兵 马汀山 居文平 郭中旭 刘永林 李�昊 温婷 王春燕 王伟 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种多源一体自动切换的联合供汽系统和方法,该系统采用高、低参数双路或多路汽源。常规情况下,各汽源的压力相近,温度不同；不同汽源在并管后其蒸汽接入同一减温减压装置进行参数调节,随后经同一管道输送外供。通过上述的系统设置,可以在汽源切换时大幅减少减温减压装置前的管道暖管时间；不需要对减温减压装置后的管道进行再次暖管,减少相应暖管工作量和暖管过程的工质损失。(The invention discloses a multi-source integrated automatic switching combined steam supply system and a method. Under the conventional condition, the pressure of each steam source is similar, and the temperature is different; after different steam sources are combined, the steam is connected to the same temperature and pressure reducing device for parameter adjustment, and then is conveyed to the outside through the same pipeline for supplying. By the system arrangement, the time for heating the pipeline in front of the temperature and pressure reducing device can be greatly reduced when the steam source is switched; the pipeline after the temperature and pressure reducing device does not need to be heated again, so that the workload of the corresponding heating pipe and the working medium loss in the pipe heating process are reduced.)

1. A multi-source integrated automatic switching combined steam supply system is characterized by comprising a first steam source and a second steam source, wherein the first steam source is connected to a first pipeline (37), the second steam source is connected to a second pipeline (38), the terminal end of the first pipeline (37) and the terminal end of the second pipeline (38) are converged to a collecting pipe (39), and the terminal end of the collecting pipe (39) is connected to a steam supply main pipe;

the first pipeline (37) is provided with a first air source steam extraction isolation valve (1) and a first air source steam extraction check valve (2), the first pipeline (37) is communicated with a first connecting pipeline (40) in front of the first air source steam extraction isolation valve (1), the first pipeline (37) is communicated with a second connecting pipeline (41) behind the first air source steam extraction check valve (2), and the other ends of the first connecting pipeline (40) and the second connecting pipeline (41) are both connected to a drainage flash tank;

in the direction from the drainage flash tank to the first pipeline (37), a first electric drainage valve (7) and a first manual drainage stop valve (6) are sequentially arranged on the first connecting pipeline (40), and a second electric drainage valve (9) and a second manual drainage stop valve (8) are sequentially arranged on the second connecting pipeline (41);

the second pipeline (38) is provided with a steam source second steam extraction isolation valve (10) and a steam source second steam extraction check valve (11), the second pipeline (38) is communicated with a third connecting pipeline (43) in front of the steam source second steam extraction isolation valve (10), the second pipeline (38) is communicated with a fourth connecting pipeline (44) behind the steam source second steam extraction check valve (11), and the other ends of the third connecting pipeline (43) and the fourth connecting pipeline (44) are both connected to a drainage flash tank;

in the direction from the drainage flash tank to the second pipeline (38), a third electric drainage valve (16) and a third manual drainage stop valve (15) are sequentially arranged on the third connecting pipeline (43), and a fourth electric drainage valve (18) and a fourth manual drainage stop valve (17) are sequentially arranged on the fourth connecting pipeline (44);

a pressure reducing valve (19) is arranged on the collecting pipe (39), a fifth connecting pipeline (45) is connected to the rear end of the collecting pipe (39) at the pressure reducing valve (19), and a desuperheater (27) is arranged at the connection position of the collecting pipe (39) and the fifth connecting pipeline (45); the other end of the fifth connecting pipeline (45) is connected to a self-temperature-reducing water source.

2. The combined steam supply system with the integrated automatic switching of the multiple sources according to claim 1, wherein a steam source-steam extraction pressure measuring point (3), a steam source-steam extraction temperature measuring point (4) and a steam source-steam extraction pipeline wall temperature measuring point (5) are sequentially arranged on the first pipeline (37) behind the second connecting pipeline (41).

3. The combined steam supply system with the integrated automatic switching of the multiple sources according to claim 1, wherein a second steam source extraction pressure measuring point (12), a second steam source extraction temperature measuring point (13) and a second steam source extraction pipeline wall temperature measuring point (14) are sequentially arranged on the second pipeline (38) after the fourth connecting pipeline (44).

4. The multi-source integrated automatic switching combined steam supply system according to claim 1, wherein a desuperheating water regulating valve inlet throttle valve (32), a desuperheating water regulating valve (31) and a desuperheating water check valve (28) are sequentially arranged on a fifth connecting pipeline (45) from a desuperheating water source to a collecting pipe (39).

5. The combined steam supply system with integrated automatic switching of multiple sources according to claim 4, characterized in that the fifth connecting pipeline (45) is provided with a desuperheating water regulating valve inlet stop valve (33) in front of the desuperheating water regulating valve inlet throttle valve (32), and the fifth connecting pipeline (45) is provided with a desuperheating water regulating valve outlet stop valve (30) behind the desuperheating water regulating valve (31).

6. The combined steam supply system with integrated automatic switching of multiple sources according to claim 5, characterized in that the fifth connecting pipeline (45) is provided with a branch (46), and a second desuperheating water regulating valve bypass stop valve (35) and a first desuperheating water regulating valve bypass stop valve (34) are arranged on the branch (46).

7. The combined steam supply system for multi-source integrated automatic switching of the claim 1 is characterized in that the collecting pipe (39) is provided with a temperature and pressure reducing device outlet safety valve (20), a steam supply isolating valve (24) and a steam supply regulating valve (25) in sequence after a temperature reducing device (27).

8. The combined steam supply system with the integrated automatic switching of the multiple sources according to claim 7, wherein a steam supply pressure measuring point (21), a steam supply temperature measuring point (22) and a steam supply pipeline wall temperature measuring point (23) are arranged between the pressure reducer outlet safety valve (20) and the steam supply isolation valve (24).

9. The combined steam supply system with integrated automatic switching of multiple sources according to any one of claims 1 to 8, characterized in that a second steam source extraction pressure reducing valve (36) is arranged on a second pipeline (38) between the second steam source extraction check valve (11) and the fourth connecting pipeline (44).

10. The combined steam supply method of the multi-source integrated automatic switching combined steam supply system based on claim 1 is characterized in that when a steam supply pipeline of a steam supply main pipe is switched from a first air source to a second air source or from the second air source to the first air source, the switching steps are as follows:

step 1, opening an electric drain valve of a new steam supply pipeline, opening a steam extraction isolating valve of the new steam supply pipeline, and gradually closing the steam extraction isolating valve of an original steam supply pipeline;

step 2, closing the electric drain valve of the new steam supply pipeline, gradually increasing the opening of the steam extraction isolation valve of the new steam supply pipeline, gradually reducing the opening of the steam extraction isolation valve of the original steam supply pipeline, continuously adjusting the opening of a pressure reducing valve (19) in the switching process, and keeping the steam supply parameters stable;

and step 3, finally, completely opening the steam extraction isolation valve of the new steam supply pipeline, and completely closing the steam extraction isolation valve of the original steam supply pipeline.

Technical Field

The invention belongs to the technical field of thermal power generation and atomic power generation, and particularly relates to a multi-source integrated automatic switching combined steam supply system and method.

Background

In recent years, the installed scale of new wind power and photovoltaic energy is continuously increased, the integral power consumption scale is also greatly improved, and the peak regulation contradiction of a power grid is increasingly prominent. In order to relieve the contradiction of the difference adjustment gap and improve the peak adjustment capability of the master control unit, each local dispatching control center continuously establishes and perfects the deep peak adjustment technical specification on the basis of summarizing the deep peak adjustment work.

At present, various domestic power plants generally select a reasonable steam extraction steam source scheme according to the steam using parameter requirements of users, the most widely applied medium-parameter steam supply is cold re-steam extraction and hot re-steam extraction, and a specific technical route is determined according to steam supply flow and steam supply parameters. With the continuous increase of the deep peak regulation requirement, the low-load operation of the unit becomes a normal state, under the working condition, the low-load operation is limited by the temperature limit of a boiler reheater, the cold re-allowable steam extraction flow rate is reduced along with the reduction of the load, and in order to continuously maintain the sufficient steam supply flow rate, the hot re-steam extraction needs to be switched to.

Because the two sets of system parameters have larger difference and are relatively independent in design and modification, long-time heating pipes and corresponding equipment and system investment, switching and quit operation are required during system switching, and the workload of operators can be obviously increased for a unit with larger electric load fluctuation. In addition, if the difference between the design flow rates of the cold recycling system and the hot recycling system is large, the problem that the hot recycling system cannot be smoothly put into and operated under the condition of low steam supply flow rate can also occur.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a multi-source integrated automatic switching combined steam supply system and a multi-source integrated automatic switching combined steam supply method so as to solve the problems that in the prior art, two types of steam sources of a cold recycling system and a hot recycling system are difficult to switch rapidly and are difficult to input and operate smoothly after switching.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a multi-source integrated automatic switching combined steam supply system comprises a first steam source and a second steam source, wherein the first steam source is connected to a first pipeline, the second steam source is connected to a second pipeline, the terminal of the first pipeline and the terminal of the second pipeline are converged to a collecting pipe, and the terminal of the collecting pipe is connected to a steam supply main pipe;

the first pipeline is provided with a first gas source steam extraction isolation valve and a first gas source steam extraction check valve, the first pipeline is communicated with a first connecting pipeline in front of the first gas source steam extraction isolation valve, the first pipeline is communicated with a second connecting pipeline behind the first gas source steam extraction check valve, and the other ends of the first connecting pipeline and the second connecting pipeline are both connected to the drainage flash tank;

in the direction from the drainage flash tank to the first pipeline, a first electric drain valve and a first manual drain stop valve are sequentially arranged on the first connecting pipeline, and a second electric drain valve and a second manual drain stop valve are sequentially arranged on the second connecting pipeline;

the second pipeline is provided with a steam source second steam extraction isolation valve and a steam source second steam extraction check valve, the second pipeline is communicated with a third connecting pipeline in front of the steam source second steam extraction isolation valve, the second pipeline is communicated with a fourth connecting pipeline behind the steam source second steam extraction check valve, and the other ends of the third connecting pipeline and the fourth connecting pipeline are both connected to the drainage flash tank;

in the direction from the drainage flash tank to the second pipeline, a third electric drain valve and a third manual drainage stop valve are sequentially arranged on the third connecting pipeline, and a fourth electric drain valve and a fourth manual drainage stop valve are sequentially arranged on the fourth connecting pipeline;

the manifold is provided with a pressure reducing valve, the rear end of the pressure reducing valve of the manifold is connected with a fifth connecting pipeline, and a temperature reducer is arranged at the joint of the manifold and the fifth connecting pipeline; the other end of the fifth connecting pipeline is connected to a self-temperature-reducing water source.

The invention is further improved in that:

preferably, a steam source-steam extraction pressure measuring point, a steam source-steam extraction temperature measuring point and a steam source-steam extraction pipeline wall temperature measuring point are sequentially arranged on the first pipeline behind the second connecting pipeline.

Preferably, a second steam extraction pressure measuring point of the steam source, a second steam extraction temperature measuring point of the steam source and a wall temperature measuring point of a second steam extraction pipeline of the steam source are sequentially arranged on the second pipeline behind the fourth connecting pipeline.

Preferably, the fifth connecting pipeline is sequentially provided with a desuperheating water regulating valve inlet throttle valve, a desuperheating water regulating valve and a desuperheating water check valve from a desuperheating water source to the collecting pipe.

Preferably, the fifth connecting pipeline is provided with a temperature reduction water regulating valve inlet stop valve in front of the temperature reduction water regulating valve inlet throttle valve, and the fifth connecting pipeline is provided with a temperature reduction water regulating valve outlet stop valve behind the temperature reduction water regulating valve.

Preferably, the fifth connecting pipeline is provided with a branch, and a second temperature-reducing water regulating valve bypass stop valve and a first temperature-reducing water regulating valve bypass stop valve are arranged on the branch.

Preferably, the collecting pipe is sequentially provided with a safety valve at the outlet of the temperature-reducing pressure reducer, a steam supply isolating valve and a steam supply regulating valve behind the temperature reducer.

Preferably, a steam supply pressure measuring point, a steam supply temperature measuring point and a steam supply pipeline wall temperature measuring point are arranged between the pressure reducer outlet safety valve and the steam supply isolation valve.

Preferably, a second pipeline between the second steam extraction check valve of the steam source and the fourth connecting pipeline is provided with a second steam extraction pressure reducing valve of the steam source.

When a steam supply pipeline of a steam supply main pipe is switched from a first air source to a second air source or from the second air source to the first air source, the switching steps are as follows:

step 1, opening an electric drain valve of a new steam supply pipeline, opening a steam extraction isolating valve of the new steam supply pipeline, and gradually closing the steam extraction isolating valve of an original steam supply pipeline;

step 2, closing the electric drain valve of the new steam supply pipeline, gradually increasing the opening of the steam extraction isolation valve of the new steam supply pipeline, gradually reducing the opening of the steam extraction isolation valve of the original steam supply pipeline, continuously adjusting the opening of the pressure reducing valve 19 in the switching process, and keeping the steam supply parameters stable;

and step 3, finally, completely opening the steam extraction isolation valve of the new steam supply pipeline, and completely closing the steam extraction isolation valve of the original steam supply pipeline.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a multi-source integrated automatic switching combined steam supply system, which adopts a high-parameter and low-parameter double-path or multi-path steam source. Under the conventional condition, the pressure of each steam source is similar, and the temperature is different; after different steam sources are combined, the steam is connected to the same temperature and pressure reducing device for parameter adjustment, and then is conveyed to the outside through the same pipeline for supplying. By the system arrangement, the time for heating the pipeline in front of the temperature and pressure reducing device can be greatly reduced when the steam source is switched; the pipeline after the temperature and pressure reducing device does not need to be heated again, so that the workload of the corresponding heating pipe and the working medium loss in the pipe heating process are reduced; remotely switching steam sources and judging system states; the system integrates a cold re-steam extraction system and a hot re-steam extraction system or other similar systems, reduces frequent system switching under a deep peak regulation working condition on the basis of reducing the total investment, reduces the workload of operators, simplifies the system and reduces the total space occupied by the original steam extraction system.

Furthermore, under the condition of large pressure difference of the steam source, a set of pressure reducing valve can be additionally arranged on the steam source pipeline with remarkably higher pressure to adjust parameters.

The invention also discloses a combined steam supply method of the combined steam supply system based on multi-source integrated automatic switching, which can carry out one-key automatic switching under the condition of requirement through reasonably designed control logic and valve combination, thereby greatly reducing the workload and the field operation time of operators in the system switching process; the temperature and pressure reducing device and the steam conveying pipelines behind the temperature and pressure reducing device are designed and arranged in a unified manner, so that the repeated investment and excessive occupation of the pipelines and equipment of a multi-steam-source steam extraction system are avoided, the civil engineering supporting construction amount along the pipelines and the load burden on corresponding buildings and structures are reduced, and the additional reinforcement cost is avoided; the system is clear, the pipeline is simple, and the workload of construction, operation, overhaul and maintenance is reduced.

Drawings

FIG. 1 is a schematic diagram of a conventional dual steam source system;

FIG. 2 is a schematic view of a system structure with two steam sources having a large pressure difference and an additional pressure reducing valve;

in the figure, 1-a steam source-a steam extraction isolation valve; 2-a steam extraction check valve of the steam source; 3-a steam extraction pressure measuring point of a steam source; 4-a steam extraction temperature measuring point of the steam source; 5-measuring a wall temperature of a steam extraction pipeline of the steam source; 6-a first manual drain cut-off valve; 7-a first electrically operated trap; 8-a second manual drain stop valve; 9-a second electrically operated trap; 10-a steam source two-extraction isolation valve; 11-a steam source two-steam extraction check valve; 12-a steam extraction pressure measuring point of a steam source II; 13-a steam extraction temperature measuring point of a steam source II; 14-measuring point of wall temperature of steam extraction pipeline of steam source two; 15-a third manual drain cut-off valve; 16-a third electrically operated trap; 17-a fourth manual drain cut-off valve; 18-a fourth electrically operated trap; 19-a pressure relief valve; 20-a safety valve at the outlet of the temperature and pressure reducer; 21-steam supply pressure measuring point; 22-steam supply temperature measuring point; 23-measuring point of wall temperature of steam supply pipeline; 24-a steam supply isolation valve; 25-steam supply regulating valve; 26-steam supply flow measuring point; 27-a desuperheater; 28-a desuperheating water check valve; 29-reduced water flow measurement point; 30-outlet stop valve of temperature-reducing water regulating valve; 31-a temperature-reducing water regulating valve; 32-inlet throttle valve of temperature-reducing water regulating valve; 33-a stop valve at the inlet of the temperature-reducing water regulating valve; 34-a first temperature-reducing water regulating valve bypass stop valve; 35-a second desuperheating water regulating valve bypass stop valve; 36-steam source two steam extraction pressure reducing valve; 37-a first conduit; 38-a second conduit; 39-a collector pipe; 40-a first connection line; 41-a second connecting line; 43-a third connecting line; 44-a fourth connecting line; 45-fifth connecting line; 46-branch.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

in the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly and encompass, for example, both fixed and removable connections; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1 and 2, a schematic diagram of a system employing a dual steam source is shown.

Example 1

Fig. 1 shows that in a conventional case, the pressure of the first steam source and the temperature of the second steam source are similar but different, the first steam source is communicated to a first pipeline 37, a first steam source steam extraction isolation valve 1 and a first steam source steam extraction check valve 2 are sequentially arranged on the first pipeline 37 along the steam flow direction, the first pipeline 37 is communicated with a first connecting pipeline 40 in front of the first steam source steam extraction isolation valve 1, and the first connecting pipeline 40 is connected to a drain flash tank. From the direction of first pipeline 37 to hydrophobic flash tank, be provided with first manual hydrophobic stop valve 6 and first electronic hydrophobic stop valve 7 on the first connecting line 40, first manual water delivery is cut to the manual hydrophobic stop valve before valve 6 is the steam source first steam extraction isolating valve, and first electronic hydrophobic stop valve 7 is the electronic hydrophobic stop valve before the steam source first steam extraction isolating valve. The first line 37 is connected to the second connecting line 41 after the first extraction check valve 2 of the steam source, and the second connecting line 41 is connected to the drain flash tank. From the direction of first pipeline 37 to hydrophobic flash tank, set up manual hydrophobic stop valve 8 of second and electronic trap 9 on the second connecting line 41, the manual hydrophobic stop valve 8 of second is the manual hydrophobic stop valve behind the steam source first extraction check valve, and electronic trap 9 of second is behind the steam source first extraction check valve. The first pipeline 37 is provided with a steam source-steam extraction pressure measuring point 3, a steam source-steam extraction temperature measuring point 4 and a steam source-steam extraction pipeline wall temperature measuring point 5 behind the second connecting pipeline 41, and the first pipeline 37 is connected to the collecting pipe 39 behind the steam source-steam extraction pipeline wall temperature measuring point 5. All of the hydrophobic flash tanks of the present invention may be one or more hydrophobic flash tanks.

The second steam source is communicated to a second pipeline 38, a second steam source steam extraction isolation valve 10 and a second steam source steam extraction check valve 11 are sequentially arranged on the second pipeline 38 along the steam flow direction, the second pipeline 38 is communicated with a third connecting pipeline 43 in front of the second steam source steam extraction isolation valve 10, and the third connecting pipeline 43 is connected to a drainage flash tank. From the direction of the second pipeline 38 to the drain flash tank, a third manual drain stop valve 15 and a third electric drain stop valve 16 are arranged on the third connecting pipeline 43, the third manual drain stop valve 15 is a manual drain stop valve in front of the steam source second steam extraction isolation valve 10, and the third electric drain stop valve 16 is an electric drain stop valve in front of the steam source second steam extraction isolation valve 10. The second line 38 is connected to a fourth connecting line 44 after the second extraction check valve 11 of the steam source, and the fourth connecting line 44 is connected to the drain flash tank. From the direction of the second pipeline 38 to the drainage flash tank, a fourth manual drainage stop valve 17 and a fourth electric drainage valve 18 are arranged on the fourth connecting pipeline 44, the fourth manual drainage stop valve 17 is a manual drainage stop valve behind the steam source two-steam extraction check valve 11, and the fourth electric drainage valve 18 is an electric drainage valve behind the steam source two-steam extraction check valve 11. The second pipeline 38 is provided with a steam source two-extraction pressure measuring point 12, a steam source two-extraction temperature measuring point 13 and a steam source two-extraction pipeline wall temperature measuring point 14 behind a fourth connecting pipeline 44, and the second pipeline 38 is connected to the collecting pipe 39 behind the steam source two-extraction pipeline wall temperature measuring point 14.

The first and second lines 37, 38 merge into a collecting line 39.

The pressure reducing valve 19, the temperature and pressure reducing valve outlet safety valve 20, the air supply pressure measuring point 21, the steam supply temperature measuring point 22, the steam supply pipeline wall temperature measuring point 23, the steam supply isolating valve 24, the steam supply regulating valve 25 and the steam supply flow measuring point 26 are sequentially arranged on the collecting pipe 39 along the direction of air flow, and the terminal of the collecting pipe 39 is connected to a steam supply main pipe.

The confluence pipe 39 is connected with a fifth connecting pipeline 45 between the pressure reducing valve 19 and the pressure reducing reducer outlet safety valve 20, the terminal of the fifth connecting pipeline 45 is connected to a self-temperature-reducing water source, and the direction from the temperature-reducing water source to the confluence pipe 39 is followed, a temperature-reducing water regulating valve inlet stop valve 33, a temperature-reducing water regulating valve inlet throttle valve 22, a temperature-reducing water regulating valve 31, a temperature-reducing water regulating valve outlet stop valve 30, a temperature-reducing water flow measuring point 29, a temperature-reducing water check valve 28 and a temperature reducer 27 are sequentially arranged on the fifth connecting pipeline 45, and the temperature reducer 27 is arranged at the intersection of the fifth connecting pipeline 45 and the confluence pipe 39. The fifth connecting pipeline 45 is provided with a branch 46, the starting point of the branch 46 is a self-temperature-reducing water source, and the end point is the fifth connecting pipeline 45 between the temperature-reducing water regulating valve outlet stop valve 30 and the temperature-reducing water flow measuring point 29. Along the direction of water flow, the branch 46 is provided with a second desuperheating water regulating valve bypass stop valve 35 and a first desuperheating water regulating valve bypass stop valve 34 in sequence.

The working principle of the embodiment is as follows:

when the system is operated, a single steam source (a steam source I or a steam source II) is firstly put into the system for heating the pipe, the other steam source is also in the pipe heating process after the pipeline behind the isolation valve and the check valve, and the system is put into operation formally after the steam extraction pipeline which is put into the steam source and the pipeline behind the isolation valve and the check valve which are connected with the steam extraction pipeline are heated.

At the moment, the pipeline of the other non-commissioning steam source behind the isolation valve and the check valve is already heated to a higher temperature equivalent to the commissioning steam source, and the pipeline in front of the isolation valve and the check valve is the same as the steam extraction steam source, so that when the steam source needs to be switched, the temperature required by work can be quickly reached, and long-time pipe heating operation is avoided.

If the steam source is not put into operation, the pipeline behind the isolating valve and the check valve exceeds the steam temperature of the low-temperature steam source, and further heating pipes are not needed in the putting into operation process; if the steam source which is not put into operation is a high-temperature steam source, the pipeline behind the isolation valve and the check valve reaches a higher temperature, and the length of the required heating pipe is shorter, the time for heating the secondary heating pipe in the putting into operation is shorter, and the time for heating the heating pipe can be greatly reduced.

The section of pipeline is provided with a drain valve in front of and behind the isolation valve and the check valve, and the electric drain valve is used for controlling, when the steam source is required to be switched, the drain valve can be opened remotely as required, and the newly-input steam source of the system is judged to reach a stable operation state by observing the temperature display of the pipeline wall temperature and the steam temperature measuring point, so that the steam source switching is completed.

In the steam source switching process, the opening degree of the isolation valve of the high-pressure steam source is gradually reduced, the opening degree of the isolation valve of the low-pressure steam source is gradually increased, and the safe switching of the system is realized by maintaining the stable change of the pressure of the two steam sources.

The operation can be automatically switched by one key under the condition of requirement through reasonably designed control logic and valve combination, and the workload of operators in the system switching process is greatly reduced.

Because the design parameters of the pipeline behind the temperature and pressure reducing device (the pressure reducing valve 19 and the desuperheater 27) are consistent aiming at different steam sources, the pipeline at the section does not relate to the problem of secondary heating in the steam source switching process, and the working medium waste in the heating process can be reduced while the heating time and the workload are reduced.

Taking the combined supply system of cold re-extraction and hot re-extraction by adopting the method as an example, common external steam supply parameters of 1.8MPa, 300 ℃ and steam supply flow rate of 50t/h are selected, and a conventional 300 MW-grade subcritical unit is adopted, the cold re-extraction and hot re-extraction can meet the steam supply requirements under high load, after the load is reduced, the opening degree of a combined regulating valve is reduced in cooperation with medium pressure, the pressure and the temperature of the combined regulating valve can still meet the requirements, but the combined supply system is limited by the safety limit value of the temperature of a reheater, the flow rate of the cold re-extraction can not meet the requirements, and at the moment, the cold re-extraction is switched to the hot re-extraction.

The working method of the embodiment comprises the following steps:

with reference to the system schematic of fig. 1, cold is taken as the first steam source, and hot is taken as the second steam source. At the moment, a first steam extraction isolation valve 1 and a first steam extraction check valve 2 of the steam source are opened, and a second steam extraction isolation valve 10 and a second steam extraction check valve 11 of the steam source are closed; the first manual drain stop valve 6, the second manual drain stop valve 8, the third manual drain stop valve 15 and the fourth manual drain stop valve 17 are opened, and the first electric drain valve 7, the second electric drain valve 9, the third electric drain valve 16 and the fourth electric drain valve 18 are closed.

The reheating steam extraction is carried out before the steam source two-steam extraction isolating valve 10, the temperature is about 538 ℃, the cold reheating steam extraction is carried out after the steam source two-steam extraction check valve 11, and the temperature is about 330 ℃.

In order to switch the system from the first steam source to the second steam source, the third electric steam trap 16 and the fourth electric steam trap 18 of the steam traps should be properly opened, the steam extraction isolation valve 10 is slightly opened to about 5% of opening degree, the hot re-steam extraction pipeline is heated, and simultaneously, the possibly existing drainage before and after the valve is timely discharged.

When the steam source two-extraction isolation valve 10 is opened, the opening degree of the steam source one-extraction isolation valve 1 is reduced, parameters of the steam source one-extraction pressure measuring point 3 and the steam source two-extraction pressure measuring point 12 are kept basically stable, parameters of the steam source two-extraction temperature measuring point 13 are stably increased, meanwhile, a steam supply flow measuring point 26 is kept stable, the temperature-reducing water flow regulating valve 31 automatically tracks parameters of the steam supply temperature measuring point 22 for regulation, and steam supply temperature is kept in a rated range.

At this time, because the temperature of the pipeline is already high, the pipeline can reach the working temperature quickly after the steam source two-steam extraction isolation valve 10 and the steam source two-steam extraction check valve 11 reach the front of the temperature reduction pressure reducer, (specifically, the temperature reduction pressure reducer comprises a pressure reducing valve 19, a temperature reducer 27, a temperature reduction pressure reducer outlet safety valve 20, a steam supply isolation valve 24, a steam supply adjusting valve 26, a temperature reduction water check valve 28, a temperature reduction water flow measuring point 29 and a device after the temperature reduction water flow measuring point), then the third electric drain valve 16 and the fourth electric drain valve 18 are closed, the opening degree of the steam source two-steam extraction isolation valve 10 is gradually increased, the opening degree of the steam source one-steam extraction isolation valve 1 is gradually reduced, and the system is switched from the steam source to the steam source two. During the period, because the pressure of the steam source II is slightly lower than that of the steam source I, the opening degree of the pressure reducing valve 19 is increased so as to maintain the stable parameters of the steam supply pressure measuring point 21; because the temperature of the steam source II is obviously higher than that of the steam source I, the opening degree of the temperature-reducing water regulating valve 31 is obviously increased so as to maintain the stable parameters of the steam supply temperature measuring point 22; in order to maintain the parameters of the steam supply flow measuring point 26 stable, the opening degree of the steam supply regulating valve 25 is automatically adjusted according to the parameters of the steam supply flow measuring point 26.

When the first steam extraction isolation valve 1 of the steam source is completely closed, the parameters of the first steam extraction temperature measuring point 4 of the steam source and the second steam extraction temperature measuring point 13 of the steam source are similar, the parameters of the first steam extraction pressure measuring point 3 of the steam source and the second steam extraction pressure measuring point 12 of the steam source are similar, the parameters of the first steam extraction pipeline wall temperature measuring point 5 of the pipeline wall temperature, the second steam extraction pipeline wall temperature measuring point 14 of the steam source and the steam supply pipeline wall temperature measuring point 23 are normal, the steam source switching of the system is completed, and the first electric drain valve 7 and the second electric drain valve 9 are closed.

The process can be controlled by one-key switching through reasonably setting automatic control logic, and the workload and the field operation time of workers are greatly reduced. Through reasonable debugging and setting, the automatic switching of the steam source under the change of the unit load or the change of the steam supply flow can be carried out, and the advantages of the system are further exerted.

In the case of the example 2, the following examples are given,

referring to fig. 2, in order to adjust the parameters of the second pipeline 38 of the second steam source with a significantly higher pressure in the case of a larger steam source pressure difference, a set of second steam extraction pressure reducing valve 36 of the second steam source is added, and the second steam extraction pressure reducing valve 36 of the second steam source is arranged between the 4 th connecting pipelines 44 of the second steam extraction isolation valve 10 of the second steam source. The portions not mentioned in this example are the same as those in example 1.

The case where the number of steam sources is larger can be referred to as performing the pipe addition.

The invention discloses a multi-source integrated automatic switching combined steam supply system, which adopts a high-parameter and low-parameter double-path or multi-path steam source. Under the conventional condition, the pressure of each steam source is similar, and the temperature is different; under the condition of large pressure difference of the steam source, a set of pressure reducing valve can be additionally arranged on the steam source pipeline with remarkably higher pressure to adjust parameters. After different steam sources are combined, the steam is connected to the same temperature and pressure reducing device for parameter adjustment, and then is conveyed to the outside through the same pipeline for supplying. The method is characterized by taking the combined supply of reheater cold section (hereinafter referred to as cold re) steam extraction and reheater hot section (hereinafter referred to as hot re) steam extraction of a double-path steam source as an example, wherein a high-temperature steam source is hot re-steam extraction, a low-temperature steam source is cold re-steam extraction, the high-temperature steam source and the low-temperature steam source are connected to the same temperature and pressure reducing device, and a pipeline system at the outlet of the temperature and pressure reducing device is shared.

The materials of all pipelines, valves and the like before temperature and pressure reduction are designed and selected according to the high-temperature and high-pressure parameters in each path of steam source.

The outlet pressure of the external steam supply is adjusted by a pressure reducing valve in the temperature and pressure reducing device, so that the outlet pressure of the temperature and pressure reducing device is kept stable.

The outlet temperature of the external steam supply is adjusted by a desuperheater in the desuperheating and depressurizing device, so that the outlet temperature of the desuperheating and depressurizing device is kept stable.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.