Temporary system for depressurization blowpipe of high-parameter thermal power generating unit

Abstract

The utility model discloses a high-parameter thermal power generating unit depressurization blowpipe temporary system, which belongs to the technical field of unit depressurization blowpipes and comprises a primary steam-water system, a secondary steam system, a target plate device and a silencer which are sequentially connected. The primary steam-water system comprises a separator, a superheater and a main steam pipeline which are connected in sequence, the secondary steam system comprises a hot resteam pipeline, a reheater and a cold resteam pipeline which are connected in sequence, the cold resteam pipeline is provided with a main adjacent blowing door, the main steam pipeline is communicated with the cold resteam pipeline through a high-pressure bypass pipeline, and the reheater is communicated with the high-pressure bypass pipeline. And the high-pressure bypass pipeline is provided with a high-pressure bypass adjacent blowing door. The secondary steam system and the high-pressure bypass system both participate in pipe blowing heat storage, the effective time of pipe blowing each time can be prolonged, the pipe blowing frequency is reduced, high efficiency and energy conservation are achieved, and stress damage to a boiler is relieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of unit pressure reduction and pipe blowing, in particular to a temporary system for pressure reduction and pipe blowing of a high-parameter thermal power unit. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] In order to improve the power generation efficiency of thermal power units, new infrastructure units mostly use ultra-supercritical parameters (main steam pressure above 27MPa, main steam temperature above 600℃), the design pressure of the reheat steam system is also increased to above 6MPa, and the cold reheat steam pipeline also uses alloy steel with a temperature resistance of over 500℃. Such units are called high-parameter (or high-efficiency) thermal power units.

[0004] The steam for steam pipe blowing recommended in the "Guidelines for Steam Pipe Blowing of Thermal Power Construction Project Units" (hereinafter referred to as the "Blowing Guidelines") is from the primary steam-water system composed of the water-cooled wall, the startup system and the superheater system. As the higher the steam parameter design value of the boiler, the smaller the heat storage capacity of the primary steam-water system, when the high-parameter thermal power units are blown by pressure reduction, problems such as: the steam temperature is high and difficult to control, the pre-blow door is easy to get stuck, the effective time of each blow is short, the superheater blow coefficient is low during "one-stage blow", and the number of blows is high during "two-stage blow" (more than 200 times). In short, the difficulty of pressure reduction and blowing of high-parameter thermal power units is significantly higher than that of low-parameter units, and technical innovation of the pressure reduction and blowing method is needed.

[0005] According to the "Guidelines for Blowing", the pressure-reducing method of blowing is divided into two types: "two-stage blowing" and "one-stage blowing". "Two-stage blowing" is to first blow the superheater and its piping system separately, and then blow the superheater, reheater and their piping system in series; "one-stage blowing" is to install a particle collector at the inlet of the reheater, and directly blow the superheater, reheater and their piping system in series. The temporary blowing door of both pressure-reducing blowing methods is set at the outlet of the superheated steam pipeline. The blowing steam comes from the primary steam-water system, and the secondary steam system does not participate in the heat storage of the blowing. During the heat storage period of the blowing, the reheater is in a dry burning state. To ensure the safety of the reheater, the flue gas temperature at the furnace outlet must be strictly controlled not to be higher than 538°C.

[0006] Since the "Blowing Guidelines" require that "during each blow, the boiler must be shut down for cooling at least twice, and each shutdown and cooling time must not be less than 12 hours", "one-stage blowing" can reduce three boiler ignition and start-up times compared to "two-stage blowing", and is more economical, becoming a commonly used solution. Figure 1As shown, it includes the main pipeline system and the high-pressure bypass pipeline system, which are as follows: The main pipeline system pipe blowing steam process is: primary steam-water system (separator → superheater → main steam pipeline) → main temporary blowing door → particle collector → secondary steam system (cold re-steam pipeline → reheater → hot re-steam pipeline) → target plate device → muffler → exhaust to atmosphere.

[0007] The steam flow of the high-pressure bypass pipe system is: separator → superheater → main steam pipe → high-pressure bypass temporary blowing door → cold re-steam pipe → reheater → hot re-steam pipe → target plate → muffler → exhaust. The high-pressure bypass pipe system is purged 2-3 times before each shutdown of the main pipe system. Utility Model Content

[0008] In order to solve the technical problems existing in the prior art, the utility model provides a temporary system for reducing the pressure and blowing of a high-parameter thermal power unit, so that both the secondary steam system and the high-pressure bypass system participate in the blowpipe heat storage, which can extend the effective time of each blowpipe, thereby reducing the number of blowpipe times, which is both efficient and energy-saving and reduces stress damage to the boiler.

[0009] To achieve the above purpose, the utility model is implemented through the following technical solutions:

[0010] A temporary system for depressurizing and blowing pipes of a high-parameter thermal power unit, comprising a primary steam-water system, a secondary steam system, a target plate device and a muffler connected in sequence;

[0011] The primary steam-water system includes a separator, a superheater and a main steam pipe connected in sequence, and the secondary steam system includes a hot re-steam pipe, a reheater and a cold re-steam pipe connected in sequence, and the cold re-steam pipe is provided with a main pre-blow valve. The main steam pipe and the cold re-steam pipe are connected through a high-pressure bypass pipe, and the high-pressure bypass pipe is provided with a high-pressure bypass pre-blow valve.

[0012] According to a further technical solution, a particle collector is provided between the hot resteam pipe and the reheater.

[0013] According to a further technical solution, the main steam pipeline outlet is connected to the hot re-steam pipeline outlet.

[0014] According to a further technical solution, the secondary steam system adopts a back-blowing method.

[0015] According to a further technical solution, the main temporary blowing door is arranged at the inlet of the cold re-steam pipeline.

[0016] According to a further technical solution, the high-pressure bypass pipeline is connected in parallel with the secondary steam system.

[0017] According to a further technical solution, the high-pressure bypass blowing door adopts a gate valve with a stop function.

[0018] A further technical solution is that the steam flow direction of the temporary blowing system's main pipeline system is: separator → superheater → main steam pipeline → hot re-steam pipeline → particle collector → reheater → cold re-steam pipeline → main temporary blowing door → target plate device → silencer → exhaust to atmosphere.

[0019] A further technical solution is that the steam flow direction of the temporary blowpipe system's high-pressure bypass pipeline is: separator → superheater → main steam pipeline → high-pressure bypass temporary blowing door → cold re-steam pipeline → main temporary blowing door → target plate device → silencer → exhaust to atmosphere.

[0020] According to a further technical solution, the blowing of the main pipeline system and the blowing of the high-pressure bypass pipeline system are carried out simultaneously.

[0021] Beneficial effects of the utility model:

[0022] The utility model enables both the secondary steam system and the high-pressure bypass pipeline system to participate in the pipe blowing heat storage, greatly improving the heat storage capacity of the boiler during pipe blowing, and can extend the effective time of each pipe blowing, thereby reducing the number of pipe blowings, which is both highly efficient and energy-saving and reduces stress damage to the boiler.

[0023] In the utility model, the secondary steam system adopts a back-blowing method, and the blowpipe steam flows in the opposite direction to the designed flow direction of the pipeline, so that the connection between the primary steam-water system and the secondary steam system can be realized on the operating floor of the steam engine room. Compared with the current connection between the operating floor and the middle floor of the steam engine room, the amount of pipe materials and the construction difficulty are greatly reduced.

[0024] The high-pressure bypass pipeline system of the utility model is purged synchronously and in parallel with the main pipeline system, which reduces the resistance after the superheater and helps to improve the superheater blowpipe coefficient. The reheater flow and blowpipe coefficient can also be flexibly adjusted by controlling the opening of the high-pressure bypass pre-blow door. In the middle and late stages of the blowpipe, the superheater blowpipe coefficient can be further improved by investing in a low-pressure bypass pipeline system.

[0025] During the pipe blowing period of the utility model, the reheater does not dry burn, thereby protecting the reheater; and the boiler can also increase the operating load, thereby avoiding incomplete combustion losses caused by low-load operation.

[0026] The utility model adopts a low-pressure, high-specific-volume steam blowing pipe, and the initial steam pressure is lower than the design pressure of the reheater, which can avoid the temporary blowing door from being stuck and improve the safety of the temporary system.

[0027] In the middle and late stages of pipe blowing, the utility model can put into operation a No. 2 high pressure heater to increase the feed water temperature, which is beneficial to controlling the steam temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention.

[0029] Figure 1 This is a schematic diagram of the layout of the current "one-stage blowpipe" pressure-reducing blowpipe system;

[0030] Figure 2 This is a schematic diagram of the temporary system layout for pressure reduction and pipe blowing of a high-parameter thermal power unit according to an embodiment of the utility model. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] See also Figure 2 As shown, the embodiment of the utility model provides a temporary system for depressurizing and blowing pipes of a high-parameter thermal power unit, including a primary steam-water system, a secondary steam system, a target plate device and a muffler connected in sequence;

[0033] The primary steam-water system includes a separator, a superheater and a main steam pipe connected in sequence, and the secondary steam system includes a hot re-steam pipe, a reheater and a cold re-steam pipe connected in sequence, and the cold re-steam pipe is provided with a main pre-blow valve. The main steam pipe and the cold re-steam pipe are connected through a high-pressure bypass pipe, and the high-pressure bypass pipe is provided with a high-pressure bypass pre-blow valve.

[0034] In this embodiment, a particle collector is further provided between the hot re-steam pipeline and the reheater, and the particle collector is used to collect particulate matter carried by the equipment before the reheater and the pipeline purge steam.

[0035] The main layout features of the temporary blowpipe system are: 1. The outlet of the main steam pipeline is connected to the outlet of the hot re-steam pipeline (the connection can be achieved between the main steam valve and the middle main valve of the steam turbine), and the secondary steam system adopts a back-blowing method, and the blowpipe steam flows in the opposite direction to the designed direction; 2. The main temporary blow valve is arranged at the inlet of the cold re-steam pipeline, so that the secondary steam system participates in the blowpipe heat storage; 3. The high-pressure bypass pipeline system forms a parallel relationship with the entire secondary steam system to reduce the resistance after the superheater; 4. The high-pressure bypass temporary blow valve adopts a gate valve with a mid-stop function, which can adjust the reheater flow and the blowpipe coefficient.

[0036] In this embodiment, the secondary steam system is designed to adopt a reverse blowing method. The blowing pipe steam flow direction in the secondary steam system is opposite to the pipeline design flow direction. The primary steam-water system is connected to the reverse secondary steam system in sequence. When connecting, the main steam pipeline outlet of the primary steam-water system is connected to the hot reheating steam pipeline outlet of the secondary steam system. The connection here can be realized on the operating floor of the steam engine room. The main steam valve and the middle main valve are connected through temporary pipelines to realize the connection between the primary steam-water system and the secondary steam system. Compared with the current blowing pipe system that connects the secondary steam system in a forward direction, it is necessary to connect the operating floor to the middle floor of the steam engine room, that is, to connect the main steam valve to the cold reheating pipeline, and the amount of pipes and the construction difficulty are greatly reduced.

[0037] After the primary steam-water system is connected to the reverse secondary steam system in sequence, the main steam pipeline of the primary steam-water system is connected to the cold re-steam pipeline of the secondary steam system through a high-pressure bypass pipeline, so that the high-pressure bypass pipeline system forms a parallel relationship with the entire secondary steam system. During the pressure reduction blowpipe, the high-pressure bypass pipeline system and the main pipeline system are synchronously purged in parallel, which can reduce the resistance after the superheater and help improve the superheater blowpipe coefficient. The reheater flow and blowpipe coefficient can also be flexibly adjusted by controlling the opening of the high-pressure bypass pre-blow door set on the high-pressure bypass pipeline. In the middle and late stages of the blowpipe, the superheater blowpipe coefficient can be further improved by investing in a low-pressure bypass pipeline system.

[0038] In this embodiment, the main temporary blowing gate is set at the inlet of the cold re-steam pipeline, so that the secondary steam system participates in the pipe blowing heat storage. The high-pressure bypass pipeline system is connected in parallel with the entire secondary steam system, so that the high-pressure bypass pipeline system also participates in the pipe blowing heat storage during the pipe blowing. Therefore, the high-parameter thermal power unit pressure reduction pipe blowing temporary system enables both the secondary steam system and the high-pressure bypass pipeline system to participate in the pipe blowing heat storage, greatly improving the heat storage capacity of the boiler during the pipe blowing, and can extend the effective time of each pipe blowing, thereby reducing the number of pipe blowings, which is both efficient and energy-saving, and can also reduce stress damage to the boiler.

[0039] Both the secondary steam system and the high-pressure bypass piping system participate in the heat storage during pipe blowing, which increases the heat storage capacity of the boiler during pipe blowing and enables the use of lower initial steam parameters close to the theoretical calculated values ​​for pipe blowing, that is, low-pressure, high-specific volume steam can be used for pipe blowing. The initial steam pressure is lower than the design pressure of the reheater, which can avoid the temporary blowing door from getting stuck, improve the safety of the temporary system, and make the pipe blowing process safer.

[0040] In this embodiment, the main temporary blowing door is arranged after the reheater, so that there is always steam in the reheater during the blowing, thereby avoiding dry burning of the reheater and protecting the reheater; at the same time, because the reheater does not dry burn, the operating load of the boiler can be appropriately increased during the blowing, reducing the incomplete combustion loss and pollution caused by low-load operation of the boiler.

[0041] In this embodiment, in the middle and late stages of the pipe blowing, the No. 2 high pressure heater can be put into operation to increase the feed water temperature, which is beneficial for controlling the steam temperature within an appropriate range and avoiding excessive steam temperature that increases the operational safety risk of the temporary system.

[0042] In this embodiment, the steam flow direction of the main pipeline system of the temporary blowpipe system is: primary steam-water system (separator → superheater → main steam pipeline) → secondary steam system (hot re-steam pipeline → particle collector → reheater → cold re-steam pipeline) → main temporary blow door → target plate device → muffler → exhaust to atmosphere.

[0043] The steam flow direction of the high-pressure bypass pipeline system of the temporary blowpipe system is: separator → superheater → main steam pipeline → high-pressure bypass temporary blowing door → cold re-steam pipeline → main temporary blowing door → target plate device → muffler → exhaust to atmosphere.

[0044] The main pipeline system and the high-pressure bypass pipeline system are purged synchronously in parallel, which reduces the resistance after the superheater and increases the flow area after the superheater, which helps to improve the superheater blowpipe coefficient. The reheater flow and blowpipe coefficient can also be flexibly adjusted by controlling the opening of the high-pressure bypass pre-blow door. In the middle and late stages of the blowpipe, the superheater blowpipe coefficient can be further improved by investing in the low-pressure bypass pipeline system.

[0045] The high-parameter thermal power unit uses the pressure reduction and pipe blowing method of the above temporary system, which specifically includes:

[0046] (1) Boiler cold water flushing: The boiler is filled with water at a variable flow rate of about 25% of the rated flow rate until the water quality of the separator reaches Fe < 100 μg / L, and the cold water flushing is completed.

[0047] (2) Boiler hot water flushing: The steam turbine is turned on, vacuumized, and the boiler is ignited. The boiler water temperature is controlled to be no more than 190°C, and flushing is performed at about 30% of the rated flow rate. Through a combination of external discharge and fine treatment filtration, the water quality of the separator is gradually purified to Fe < 50μg / L, and the hot water flushing is qualified.

[0048] (3) First stage of pipe blowing: the main temporary blowing valve is fully closed and the high-pressure bypass temporary blowing valve is fully opened. The boiler temperature and pressure are increased according to the startup curve. When the steam pressure rises to 1MPa, 2MPa, and 3MPa respectively, the main temporary blowing valve is opened and three test pipe blowings are carried out to check whether the steam pipe expansion, the support and hanger force, and the temporary system are normal. If the test pipe blowing is normal, the formal blowpipe steam parameters (selected at about 4MPa and 400℃) are determined according to the pressure drop ratio of the superheater during the test pipe blowing, and the formal pipe blowing is carried out.

[0049] Furthermore, the specific steps of the formal blowpipe in the first stage include: when the boiler is heated and pressurized to the formal blowpipe steam parameters (4MPa, about 400℃), the main temporary blowpipe gate is opened for formal blowpipe, and after the superheater blowpipe pressure drop ratio is less than 1.4, the main temporary blowpipe gate is closed to full closure. The boiler is stored with heat again, and when the formal blowpipe steam parameters are reached, the next blowpipe operation is performed. This cycle is repeated, maintaining a blowpipe frequency of no more than 4 times per hour, and appropriately changing the blowpipe steam parameters to obtain a satisfactory blowpipe effect. After 10 formal blowpipes, the high-pressure bypass temporary blowpipe gate is fully closed or stopped to a partial opening, and the boiler is stored with heat again to the formal blowpipe steam parameters, and the main temporary blowpipe gate is opened for formal blowpipe, and the blowpipe coefficient of the reheater is appropriately increased by throttling the high-pressure bypass flow, and the blowpipe coefficient of the superheater still meets the requirements. After blowing 5 more times, the furnace is stopped, and the low-pressure bypass is opened for pressure relief and purge. The boiler is cooled for more than 12 hours. During this period, the pipe blowing system is thoroughly inspected and troubleshooted, the granulator, condenser, condensate pump, feed pump filter, etc. are cleaned, and sufficient desalted water is stored.

[0050] (4) The second stage of pipe blowing is to repeat the steps of the first stage. After 20 formal pipe blowings, a target shooting is arranged. Depending on the target shooting situation, the blowing can be continued for 5-10 times. The boiler is shut down again, and the low-pressure bypass is opened for pressure relief and blowing. The boiler is cooled for more than 12 hours. During this period, the equipment and system are fully inspected and faults are eliminated, the particle collector is removed, the filter screen is cleaned, and sufficient desalted water is stored.

[0051] (5) The third stage is blowing. After blowing 15 times, the target shooting test is carried out. If the target plate is qualified twice in a row, the blowing is finished. If the target plate is unqualified, the blowing is carried out after blowing 5 more times. The blowing is finished after the target plate is qualified twice in a row.

[0052] Although the above describes the specific implementation methods of the utility model in combination with the accompanying drawings, it is not intended to limit the scope of protection of the utility model. Technical personnel in the relevant field should understand that on the basis of the technical solution of the utility model, various modifications or deformations that can be made by technical personnel in this field without creative work are still within the scope of protection of the utility model.

Claims

1. A temporary system for pressure reduction and pipe blowing of high-parameter thermal power units, characterized in that: It includes a primary steam-water system, a secondary steam system, a target plate device and a silencer connected in sequence; The primary steam-water system includes a separator, a superheater and a main steam pipe connected in sequence, and the secondary steam system includes a hot re-steam pipe, a reheater and a cold re-steam pipe connected in sequence, and the cold re-steam pipe is provided with a main pre-blow valve. The main steam pipe and the cold re-steam pipe are connected through a high-pressure bypass pipe, and the high-pressure bypass pipe is provided with a high-pressure bypass pre-blow valve.

2. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: A particle collector is also provided between the hot resteam pipe and the reheater.

3. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: The main steam pipeline outlet is connected to the hot re-steam pipeline outlet.

4. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: The secondary steam system adopts a back-flushing method.

5. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: The main temporary blowing door is arranged at the inlet of the cold re-steam pipeline.

6. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: The high-pressure bypass pipeline is connected in parallel with the secondary steam system.

7. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: The high-pressure bypass blowing door adopts a gate valve with a mid-stop function.

8. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 1, characterized in that: The steam flow direction of the temporary blowpipe system in the main pipeline system is: separator → superheater → main steam pipeline → hot re-steam pipeline → particle collector → reheater → cold re-steam pipeline → main temporary blowpipe door → target plate device → muffler → exhaust to atmosphere.

9. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 8, characterized in that: The steam flow direction of the high-pressure bypass pipeline system of the temporary blowpipe system is: separator → superheater → main steam pipeline → high-pressure bypass temporary blowing door → cold re-steam pipeline → main temporary blowing door → target plate device → muffler → exhaust to atmosphere.

10. A temporary system for depressurizing and blowing pipes for high-parameter thermal power units as claimed in claim 9, characterized in that: The main pipeline system pipe blowing and the high-pressure bypass pipeline system pipe blowing are carried out simultaneously.

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