A combined cycle unit waste heat boiler blowpipe system
By introducing multi-stage steam supply devices and bypass discharge pipe groups into the waste heat boiler of the combined cycle unit, combined with the segmented temperature and pressure control flushing method, the problems of filter clogging and uneven steam pipeline pressure caused by poor water quality in the low-pressure steam drum were solved, achieving efficient and safe steam purging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN THERMAL POWER RES INST CO LTD
- Filing Date
- 2023-08-09
- Publication Date
- 2026-07-31
AI Technical Summary
During the steam purging process of the waste heat boiler in the combined cycle unit, the poor water quality of the low-pressure steam drum causes frequent clogging of the filters of the high-pressure and medium-pressure feedwater pumps, and the steam pipeline pressure is uneven when the target plate is replaced, which poses a safety risk.
A multi-stage steam supply system and a bypass discharge pipe assembly are adopted. Steam pressure is released through the bypass blow-out valve to reduce the pressure in the main blow-out pipe. Combined with a segmented temperature and pressure control flushing method, the cleanliness of the steam and the safety of the operation are ensured.
It effectively solves the problem of filter clogging, reduces the safety risks of target plate replacement, and improves the efficiency and safety of steam purging.
Smart Images
Figure CN117109017B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas-steam combined cycle power generation technology, and more particularly to a waste heat boiler blowing system for a combined cycle unit. Background Technology
[0002] A gas turbine is an internal combustion engine that uses a continuously flowing gas as its working fluid to drive a high-speed rotating impeller, converting the energy of fuel into useful work. It is a type of rotary turbine thermal engine. Powered by a gas turbine, and combined with a waste heat boiler and a steam turbine, a combined cycle gas-steam power generation system can be formed. Such a power generation system has advantages such as rapid start-up and shutdown, fast load response, and outstanding peak-shaving and frequency regulation performance.
[0003] Combined cycle power units utilize waste heat boilers to recover and reuse the exhaust heat from the gas turbine. The steam produced by the waste heat boilers is then fed into the turbines to generate electricity, thereby improving the power generation efficiency of the combined cycle system. Among related technologies, waste heat boilers with three steam drums (high, medium, and low pressure) are widely used, and they also have three heating surface systems (high, medium, and low pressure). During on-site steam purging of the waste heat boiler's steam and water pipelines, the initial low-pressure steam drum water quality is poor, leading to frequent clogging of the feedwater pump filter. Furthermore, replacing the target plates in multiple steam drums poses significant safety risks. Summary of the Invention
[0004] This invention is based on the inventor's discoveries and understanding of the following facts and problems:
[0005] During the power plant's infrastructure construction and commissioning, the newly built boiler requires steam purging of its pipelines to remove impurities from the boiler's steam-water system and ensure the cleanliness of the steam after commissioning. In practice, the waste heat boiler's low-pressure economizer, low-pressure evaporator, and other systems contain a large amount of impurities and contaminants, resulting in poor water quality in the low-pressure steam drum. This causes frequent filter clogging in the high-pressure and medium-pressure feedwater pumps, which use these pumps as their water source, necessitating shutdowns for filter cleaning. This leads to multiple interruptions in the waste heat boiler's steam blowing operation, severely impacting the project's progress.
[0006] When replacing the target plate, the blow-out valves in each steam pipe are closed, and the pressure of the three steam drums of the waste heat boiler rises, but the rate and magnitude of the pressure rise are inconsistent. When the pressure of a certain steam drum approaches the safety limit, the risk of steam leakage increases, and replacing the target plate in the steam pipe will face a greater risk of high-temperature burns.
[0007] The present invention aims to at least partially solve one of the technical problems in the related art.
[0008] To address this, embodiments of the present invention propose an efficient and safe combined cycle unit waste heat boiler blowing system. This system is used to solve the problem of frequent filter clogging in high-pressure and medium-pressure feedwater pumps, and effectively reduces the pressure of each steam drum during target plate replacement, ensuring the safety of on-site personnel.
[0009] The combined cycle unit waste heat boiler blowdown system of this invention includes: a multi-stage steam supply device, a main exhaust pipe assembly, and at least one bypass exhaust pipe assembly. The steam supply device is used to generate saturated steam using water as the working fluid. The main exhaust pipe assembly includes a main exhaust header and a multi-stage main exhaust purging pipe connected to the main exhaust header. Each of the multi-stage main exhaust purging pipes corresponds to and is connected to a different stage of the steam supply device. The main exhaust purging pipe is used to transport the saturated steam generated by its corresponding steam supply device and discharge it into the atmosphere through the main exhaust header. The main exhaust purging pipe is equipped with a steam flow direction... The main line blow-off valve and target plate are arranged at intervals from upstream to downstream. The bypass discharge pipe group includes a bypass discharge header and a multi-stage bypass purge pipe connected to the bypass discharge header. The multi-stage bypass purge pipe corresponds to and is connected to the multi-stage main line purge pipe. The connection between the bypass purge pipe and its corresponding main line purge pipe is located upstream of the main line blow-off valve in the direction of steam flow. The bypass purge pipe is used to transport saturated steam in its corresponding main line purge pipe and discharge it into the atmosphere through the bypass discharge header. A bypass blow-off valve is provided on the bypass purge pipe.
[0010] In the combined cycle unit waste heat boiler blowdown system of this invention, when replacing the target plate, the pressure of the corresponding steam supply device is released by opening the bypass blowdown valve on the bypass blowdown pipe connected to the main blowdown pipe where the target plate is located, so that the steam pressure in the main blowdown pipe is <1MPa. This reduces the pressure on the target plate on the main blowdown pipe, thereby reducing the risk of high-temperature steam leakage to the operators and improving the safety of the target plate replacement operation.
[0011] In some embodiments, the multi-stage steam supply device includes a low-pressure steam supply device, a medium-pressure steam supply device, and a high-pressure steam supply device. The multi-stage main purging pipe includes a low-pressure main purging pipe connected to the low-pressure steam supply device, a medium-pressure main purging pipe connected to the medium-pressure steam supply device, and a high-pressure main purging pipe connected to the high-pressure steam supply device. The multi-stage bypass purging pipe includes a low-pressure bypass purging pipe connected to the low-pressure main purging pipe, a medium-pressure bypass purging pipe connected to the medium-pressure main purging pipe, and a high-pressure bypass purging pipe connected to the high-pressure main purging pipe.
[0012] In some embodiments, the low-pressure steam supply device includes a condensate pump, a low-pressure economizer, a low-pressure steam drum, and a low-pressure superheater connected in sequence via pipelines, and the low-pressure main line purge pipe is connected to the low-pressure superheater.
[0013] In some embodiments, the medium-pressure steam supply device includes a medium-pressure feedwater pump, a medium-pressure economizer, a medium-pressure steam drum, and a medium-pressure superheater connected in sequence via pipelines, and the medium-pressure main line purge pipe is connected to the medium-pressure superheater.
[0014] In some embodiments, the high-pressure steam supply device includes a high-pressure feedwater pump, a high-pressure economizer, a high-pressure steam drum, and a high-pressure superheater connected in sequence via pipelines. The high-pressure main purge pipe is connected to the high-pressure superheater. The high-pressure main purge pipe is also provided with a high-pressure main steam valve, a reheater, and a medium-pressure main steam valve located upstream of the main purge valve on the high-pressure main purge pipe in the steam flow direction. The high-pressure main steam valve, the reheater, and the medium-pressure main steam valve are arranged at intervals from upstream to downstream in the steam flow direction. The combined cycle unit waste heat boiler purge system also includes a first branch pipe. The first branch pipe is connected to the medium-pressure main purge pipe and the high-pressure main purge pipe. The connection point between the first branch pipe and the medium-pressure main purge pipe is located upstream of the main purge valve on the medium-pressure main purge pipe in the steam flow direction. The connection point between the first branch pipe and the high-pressure main purge pipe is located between the high-pressure main steam valve and the reheater in the steam flow direction.
[0015] In some embodiments, the connection between the high-pressure bypass purge pipe and the high-pressure main purge pipe is located upstream of the high-pressure main steam valve in the direction of steam flow.
[0016] In some embodiments, the medium-pressure bypass purging pipe is connected to the high-pressure main purging pipe, so that the medium-pressure bypass purging pipe is connected to the medium-pressure main purging pipe via the high-pressure main purging pipe and the first branch pipe.
[0017] In some embodiments, the connection between the medium-pressure bypass purge pipe and the high-pressure main purge pipe is located between the reheater and the medium-pressure main steam valve in the direction of steam flow.
[0018] In some embodiments, the combined cycle unit waste heat boiler blowing system further includes a water supply pipe group, which includes a water supply main pipe and a first water supply sub-pipe and a second water supply sub-pipe connected to the water supply main pipe. The water supply main pipe is connected to the low-pressure steam drum, the first water supply sub-pipe is connected to the medium-pressure feedwater pump, and the second water supply sub-pipe is connected to the high-pressure feedwater pump.
[0019] In some embodiments, the combined cycle unit waste heat boiler blowing system further includes a second branch pipe, which is connected to the water supply header and the pipeline between the condensate pump and the low-pressure economizer. The water supply header is provided with a first water supply valve, and the connection between the second branch pipe and the water supply header is located downstream of the first water supply valve in the steam flow direction. The second branch pipe is provided with a second water supply valve. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the waste heat boiler blowing system of a combined cycle unit according to an embodiment of the present invention.
[0021] Figure label:
[0022] 11. Condensate pump; 12. Low-pressure economizer; 13. Low-pressure steam drum; 14. Low-pressure superheater.
[0023] 21. Medium-pressure feedwater pump; 22. Medium-pressure economizer; 23. Medium-pressure steam drum; 24. Medium-pressure superheater.
[0024] 31. High-pressure feedwater pump; 32. High-pressure economizer; 33. High-pressure steam drum; 34. High-pressure superheater.
[0025] Main line discharge header 41, main line silencer 411, low-pressure main line purge pipe 42, low-pressure main line purge valve 421, low-pressure target plate device 422, medium-pressure main line purge pipe 43, medium-pressure main line purge valve 431, medium-pressure target plate device 432, high-pressure main line purge pipe 44, high-pressure main line purge valve 441, high-pressure target plate device 442, high-pressure main steam valve 443, reheater 444, medium-pressure main steam valve 445.
[0026] Bypass discharge header 51, bypass silencer 511, low-pressure bypass purge pipe 52, low-pressure bypass purge valve 521, medium-pressure bypass purge pipe 53, medium-pressure bypass purge valve 531, high-pressure bypass purge pipe 54, high-pressure bypass purge valve 541.
[0027] Main water supply pipe 61, first water supply valve 611, first water supply sub-pipe 62, second water supply sub-pipe 63
[0028] First branch pipe 71, second branch pipe 72, second water supply valve 721. Detailed Implementation
[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0030] The combined cycle unit waste heat boiler blowing system of the present invention is described below with reference to the accompanying drawings.
[0031] like Figure 1 As shown, the combined cycle unit waste heat boiler blowing system of this invention includes: a multi-stage steam supply device, a main exhaust pipe group and at least one bypass exhaust pipe group.
[0032] The steam supply unit is connected to an external water source and generates saturated steam by heating, evaporating, and superheating the working water.
[0033] The main discharge pipe assembly includes a main discharge header 41 and multi-stage main purging pipes. The output end of the main discharge header is connected to the atmosphere, and the input end of the main discharge header is connected to the output end of the multi-stage main purging pipes via a multi-way valve (not shown in the figure). Each multi-stage main purging pipe corresponds to and is connected to a multi-stage steam supply unit. The main purging pipes are used to transport saturated steam generated by their corresponding steam supply units and discharge it into the atmosphere through the main discharge header 41. The main purging pipes are equipped with main purging valves and target plates, which are arranged at intervals from upstream to downstream in the steam flow direction.
[0034] The bypass discharge pipe assembly includes a bypass discharge header 51 and multi-stage bypass purge pipes. The output end of the header is connected to the atmosphere, and the input end of the header is connected to the output end of the multi-stage bypass purge pipes via a multi-way valve (not shown in the figure). Each multi-stage bypass purge pipe corresponds to and is connected to a multi-stage main purge pipe. The connection point between the bypass purge pipe and its corresponding main purge pipe is located upstream of the main purge valve in the steam flow direction. The bypass purge pipe is used to transport saturated steam from its corresponding main purge pipe and discharge it into the atmosphere through the bypass discharge header 51. A bypass purge valve is installed on each bypass purge pipe.
[0035] Understandably, the blow-through valve is an electrically operated valve with a specified opening and closing time, used to control the flow of purging steam. The target plate device is a mounting device for a long, narrow target plate, which is made of copper or aluminum with a certain width and low hardness, and its length spans the entire cross-section of the steam pipe. If there are impurity particles in the steam, they will impact and create dents on the target plate. Based on this principle, the target plate device can be used to inspect the purging effect in the final stage of the blow-through process.
[0036] During the steam blowing stage, the blowing valves on each pipeline in the system are closed. After the waste heat boiler absorbs heat, the working fluid in each steam supply device is heated and pressurized. When the pressure reaches the set pressure, the main blowing valve on the corresponding main blowing pipe is opened to perform steam depressurization and blowing.
[0037] If multiple steam supply units simultaneously pressurize to their respective purging pressures and require depressurization, the main purging valve of the main purging pipe of any steam supply unit can be opened, the bypass purging valve of any bypass purging pipe of another steam supply unit can be opened, and the bypass purging valve of another bypass purging pipe of yet another steam supply unit can be opened. This ensures that each steam supply unit corresponds to a different discharge header, so that the steam discharge of each steam supply unit does not affect each other.
[0038] For example, when both steam supply units need to be depressurized, if both units vent through the same discharge header, the high-pressure steam will "reverse" to the low-pressure steam, and impurities will be blown back into the low-pressure purge pipe. Therefore, by opening the main purge pipe valve of the main purge pipe and using the main discharge header 41 to vent and depressurize one steam supply unit, and by opening the bypass purge pipe valve of the bypass purge pipe and using the bypass discharge header 51 to vent and depressurize the other steam supply unit, the mutual interference of the two venting operations can be avoided.
[0039] Furthermore, when a steam supply device needs to be depressurized, the main purging valve of the main purging pipe connected to the steam supply device and the bypass purging valve of the corresponding bypass purging pipe can be opened simultaneously, thereby quickly releasing the pressure of the steam supply device and improving the pressure reduction purging effect.
[0040] Furthermore, the output end of the main discharge header 41 is equipped with a main silencer 411, and the output end of the bypass discharge header 51 is equipped with a bypass silencer 511. The silencers are used to reduce the noise when high-temperature steam is discharged from the pipeline.
[0041] After several pressure-reducing purging cycles, the impurities and contaminants in the discharge pipe group were basically cleaned up. The cleanliness of the steam was then checked by placing the corresponding target plates in the target plate device.
[0042] When replacing the target plate, the pressure of the corresponding steam supply device is released by opening the bypass blow-off valve on the bypass blow-off pipe connected to the main blow-off pipe where the target plate is located, so that the steam pressure in the main blow-off pipe is <1MPa. This reduces the pressure on the target plate on the main blow-off pipe, thereby reducing the risk of high-temperature steam leakage to the operators and improving the safety of the target plate replacement operation.
[0043] In some embodiments, such as Figure 1 As shown, the multi-stage steam supply system includes a low-pressure steam supply system, a medium-pressure steam supply system, and a high-pressure steam supply system.
[0044] The multi-stage main pipeline purging system includes a low-pressure main pipeline purging pipe 42, a medium-pressure main pipeline purging pipe 43, and a high-pressure main pipeline purging pipe 44. The input end of the low-pressure main pipeline purging pipe 42 is connected to the low-pressure steam supply unit, the input end of the medium-pressure main pipeline purging pipe 43 is connected to the medium-pressure steam supply unit, and the input end of the high-pressure main pipeline purging pipe 44 is connected to the high-pressure steam supply unit. The output ends of the low-pressure main pipeline purging pipe 42, the medium-pressure main pipeline purging pipe 43, and the high-pressure main pipeline purging pipe 44 are all connected to the input end of the main pipeline discharge header 41.
[0045] The main line blow valve and target plate on the low-pressure main line purge pipe 42 are low-pressure main line blow valve 421 and low-pressure target plate 422, respectively; the main line blow valve and target plate on the medium-pressure main line purge pipe 43 are medium-pressure main line blow valve 431 and medium-pressure target plate 432, respectively; and the main line blow valve and target plate on the high-pressure main line purge pipe 44 are high-pressure main line blow valve 441 and high-pressure target plate 442, respectively.
[0046] The multi-stage bypass purge system includes a low-pressure bypass purge pipe 52, a medium-pressure bypass purge pipe 53, and a high-pressure bypass purge pipe 54. The input end of the low-pressure bypass purge pipe 52 is connected to the low-pressure main purge pipe 42, the input end of the medium-pressure bypass purge pipe 53 is connected to the medium-pressure main purge pipe 43, and the input end of the high-pressure bypass purge pipe 54 is connected to the high-pressure main purge pipe 44. The output ends of the low-pressure bypass purge pipe 52, the medium-pressure bypass purge pipe 53, and the high-pressure bypass purge pipe 54 are all connected to the input end of the bypass discharge header 51.
[0047] The bypass blow-off valve on the low-pressure bypass purge pipe 52 is the low-pressure bypass blow-off valve 521, the bypass blow-off valve on the medium-pressure bypass purge pipe 53 is the medium-pressure bypass blow-off valve 531, and the bypass blow-off valve on the high-pressure bypass purge pipe 54 is the high-pressure bypass blow-off valve 541.
[0048] Optionally, such as Figure 1 As shown, the low-pressure steam supply unit includes a condensate pump 11, a low-pressure economizer 12, a low-pressure steam drum 13, and a low-pressure superheater 14. The inlet of the condensate pump 11 is connected to a water source via a pipeline, the outlet of the condensate pump 11 is connected to the inlet of the low-pressure economizer 12 via a pipeline, the outlet of the low-pressure economizer 12 is connected to the inlet of the low-pressure steam drum 13 via a pipeline, the outlet of the low-pressure steam drum 13 is connected to the inlet of the low-pressure superheater 14 via a pipeline, and the outlet of the low-pressure superheater 14 is connected to the inlet of the low-pressure purge pipe.
[0049] like Figure 1 As shown, the medium-pressure steam supply unit includes a medium-pressure feedwater pump 21, a medium-pressure economizer 22, a medium-pressure steam drum 23, and a medium-pressure superheater 24. The input end of the medium-pressure feedwater pump 21 is connected to a water source via a pipeline. The output end of the medium-pressure feedwater pump 21 is connected to the input end of the medium-pressure economizer 22 via a pipeline. The output end of the medium-pressure economizer 22 is connected to the input end of the medium-pressure steam drum 23 via a pipeline. The output end of the medium-pressure steam drum 23 is connected to the input end of the medium-pressure superheater 24 via a pipeline. The output end of the medium-pressure superheater 24 is connected to the input end of the medium-pressure purge pipe.
[0050] like Figure 1As shown, the high-pressure steam supply unit includes a high-pressure feedwater pump 31, a high-pressure economizer 32, a high-pressure steam drum 33, and a high-pressure superheater 34. The input end of the high-pressure feedwater pump 31 is connected to a water source via a pipeline, the output end of the high-pressure feedwater pump 31 is connected to the input end of the high-pressure economizer 32 via a pipeline, the output end of the high-pressure economizer 32 is connected to the input end of the high-pressure steam drum 33 via a pipeline, the output end of the high-pressure steam drum 33 is connected to the input end of the high-pressure superheater 34 via a pipeline, and the output end of the high-pressure superheater 34 is connected to the input end of the high-pressure purge pipe.
[0051] Among them, the high, medium, and low pressure steam drum 13 serves as the connecting hub for the three processes of working fluid heating, evaporation, and superheating. It also acts as a balancer to ensure the pressure head required for water-cooled wall circulation and is equipped with a steam-water separator to ensure the quality of saturated steam. The steam supply device in the aforementioned steam blowing stage needs to be depressurized, that is, the working fluid in the steam drum needs to be depressurized when it reaches the set pressure.
[0052] High, medium, and low-pressure economizers 12 are used to absorb heat from the gas turbine exhaust and heat the feedwater entering the steam drum. Medium and high-pressure feedwater pumps 31 and condensate pumps 11 drive the working fluid water through their respective economizers and ultimately into the corresponding steam drums, completing heat absorption and evaporation processes during the feedwater flow. High, medium, and low-pressure superheaters 14 further superheat the saturated steam discharged from the corresponding steam drums to a set temperature to meet the turbine's operating requirements.
[0053] Furthermore, such as Figure 1 As shown, the high-pressure main line purge pipe 44 is also equipped with a high-pressure main steam valve 443, a reheater 444 and a medium-pressure main steam valve 445 located upstream of the high-pressure main line purge pipe valve 441 in the steam flow direction, and the high-pressure main steam valve 443, the reheater 444 and the medium-pressure main steam valve 445 are arranged at intervals from upstream to downstream in the steam flow direction.
[0054] Furthermore, the combined cycle unit waste heat boiler blowing system of this embodiment of the invention also includes a first branch pipe 71. The input end of the first branch pipe 71 is connected to the medium-pressure main line purge pipe 43, and the output end of the first branch pipe 71 is connected to the high-pressure main line purge pipe 44. The connection between the first branch pipe 71 and the medium-pressure main line purge pipe 43 is located upstream of the medium-pressure main line blowing valve 431 in the steam flow direction. The connection between the first branch pipe 71 and the high-pressure main line purge pipe 44 is located between the high-pressure main steam valve 443 and the reheater 444 in the steam flow direction.
[0055] Specifically, such as Figure 1As shown, the connection point between the high-pressure bypass purge pipe 54 and the high-pressure main purge pipe 44 is located upstream of the high-pressure main steam valve 443 in the steam flow direction. The input end of the intermediate-pressure bypass purge pipe 53 is connected to the high-pressure main purge pipe 44, so that the intermediate-pressure bypass purge pipe 53 is connected to the intermediate-pressure main purge pipe 44 via the high-pressure main purge pipe 44 and the first branch pipe 71. The connection point between the intermediate-pressure bypass purge pipe 53 and the high-pressure main purge pipe 44 is located between the reheater 444 and the intermediate-pressure main steam valve 445 in the steam flow direction.
[0056] In some embodiments, such as Figure 1 As shown, the combined cycle unit waste heat boiler blowing system of this embodiment of the invention also includes a water supply pipe group, which includes a water supply main pipe 61, a first water supply sub-pipe 62, and a second water supply sub-pipe 63. The input end of the water supply main pipe 61 is connected to the low-pressure steam drum 13, and the output end of the water supply main pipe 61 is connected to the input end of the first water supply sub-pipe 62 and the input end of the second water supply sub-pipe 63 via a three-way valve (not shown in the figure). The output end of the first water supply sub-pipe 62 is connected to the input end of the medium-pressure feedwater pump 21, and the output end of the second water supply sub-pipe 63 is connected to the input end of the high-pressure feedwater pump 31.
[0057] Furthermore, such as Figure 1 As shown, the combined cycle unit waste heat boiler blowing system of this embodiment of the invention also includes a second branch pipe 72. The input end of the second branch pipe 72 is connected to the pipeline between the condensate pump 11 and the low-pressure economizer 12, and the output end of the second branch pipe 72 is connected to the makeup water header 61. The makeup water header 61 is provided with a first makeup water valve 611, and the connection between the second branch pipe 72 and the makeup water header 61 is located downstream of the first makeup water valve 611 in the steam flow direction. The second branch pipe 72 is provided with a second makeup water valve 721.
[0058] Understandably, during the initial stage of cold flushing, the low-pressure steam drum 13 contains a large amount of impurities. If the water from the low-pressure steam drum 13 is directly used as the water source for the medium-pressure feedwater pump 21 and the high-pressure feedwater pump 31, it will cause frequent clogging of the inlet filters of the medium-pressure feedwater pump 21 and the high-pressure feedwater pump 31, necessitating shutdown for cleaning. This would disrupt the continuous cold flushing of the waste heat boiler, prolonging the construction period for this stage. Furthermore, since the low-pressure steam drum 13 is used as the water source for the medium-pressure feedwater pump 21 and the high-pressure feedwater pump 31, the medium-pressure and high-pressure equipment would actually be flushed with the dirty water flushed from the low-pressure steam drum 13, resulting in poor cleaning effectiveness.
[0059] Therefore, in the combined cycle unit waste heat boiler blowing system of this embodiment of the invention, during the initial stage of cold flushing, the first water supply valve 611 is closed and the second water supply valve 721 is opened. Using the condensate pump 11, water is supplied to the low-pressure steam drum 13 via the low-pressure economizer 12. When the water level in the low-pressure steam drum 13 reaches approximately ±100mm, the drain valve (not shown in the figure) of the low-pressure steam drum 13 is opened to begin drainage. By adjusting the output of the condensate pump 11 and the opening of the drain valve of the low-pressure steam drum 13, the balance between the water supply and the drain volume can be controlled, thereby maintaining the low-pressure steam drum 13 within the normal liquid level range.
[0060] The medium-pressure feed water pump 21 and the high-pressure feed water pump 31 draw clean condensate through the second branch and use it to flush the medium-pressure steam drum 23 and the high-pressure steam drum 33. At the same time, the opening of their respective drain valves is controlled to flush the water while simultaneously filling and draining the steam, maintaining the liquid level of the medium-pressure steam drum 23 and the high-pressure steam drum 33 within ±300mm. This eliminates the possibility of clogging of the inlet filters of the medium-pressure feed water pump 21 and the high-pressure feed water pump 31, and greatly improves the cleaning effect of the medium-pressure and high-pressure equipment.
[0061] During the hot flushing stage, after the gas turbine is ignited, the water in the boiler is heated, which increases the solubility of impurities such as iron filings and rust, thus enhancing the flushing capacity. Similar to the cold flushing stage, the first and second water supply valves 611 and 721 are used to ensure that the condensate pump 11, medium-pressure feedwater pump 21, and high-pressure feedwater pump 31 all use clean condensate as their water source for hot flushing of the low-pressure, medium-pressure, and high-pressure equipment. Wastewater is discharged from the system through their respective drain valves. Hot flushing continues until water samples are taken from the low-pressure, medium-pressure, and high-pressure steam drums 33 and tested. If the water quality meets the standards (the concentrations of iron ions, silicon ions, etc., in the water meet the requirements of the regulations), the hot flushing is considered complete.
[0062] In related technologies, the hot flushing process involves setting a final temperature and then continuously heating the working fluid in the steam drum to that temperature. This invention proposes a segmented temperature and pressure controlled flushing method for the combined cycle unit waste heat boiler blowdown system. During the transition from a cold to a hot state in the low-pressure, medium-pressure, and high-pressure steam drums, the water temperature control within the steam drum is divided into four stages, T1-T4. During the temperature rise in each stage, the steam drum pressure follows the pressure rise rate P1-P4. Specifically:
[0063] Phase 1: T1 = 115℃, ΔP1 = 0.02MPa / min, final pressure P1 = 0.17MPa. When the actual water temperature t > T1, increase the water supply to stabilize the working fluid temperature inside the steam drum. When the actual pressure rise rate Δp > ΔP1, increase the drainage rate, open the steam drum vent valve and drain system (not shown in the diagram), and increase the pressure relief to stabilize the working fluid pressure inside the steam drum. Maintain T1 parameters for 3.0-4.0 hours during this phase, during which normal water supply and drainage flushing operations are performed.
[0064] Phase 2: T2 = 135℃, ΔP2 = 0.05MPa / min, final pressure P2 = 0.32MPa. When the actual water temperature t > T2, increase the water supply to stabilize the working fluid temperature inside the steam drum. When the actual pressure increase rate Δp > ΔP2, increase the drainage, open the steam drum vent valve and drain system, and increase the pressure relief to stabilize the working fluid pressure inside the steam drum. Maintain T2 parameters for 2.5-3.5 hours during this phase, during which normal water supply and drainage flushing operations are performed.
[0065] Third stage: T3 = 170℃, ΔP3 = 0.03MPa / min, P3 = 0.8MPa, duration 2.0-3.0 hours. The over-temperature and over-pressure control methods are the same as those described above.
[0066] Fourth stage: T4 = 190℃, ΔP4 = 0.03MPa / min, P4 = 1.3MPa, duration 2.0-3.0 hours. The methods for controlling over-temperature and over-pressure are the same as those described above.
[0067] After undergoing the segmented heating and flushing process described above, the water quality inside the steam drum will improve at a faster rate than with the traditional linear heating method, greatly improving flushing efficiency.
[0068] After the hot flushing is completed, the waste heat boiler enters the steam purging stage. To meet the demand for a large amount of water replenishment due to the significant evaporation of water in the steam drum during this stage, the second water replenishment valve 721 is closed, and the first water replenishment valve 611 is opened, switching the water source of the medium-pressure feedwater pump 21 and the high-pressure feedwater pump 31 to the low-pressure steam drum 13. After the cold flushing and hot flushing stages, the low-pressure steam drum 13 is basically clean inside, and the water quality meets the requirement that the inlet filters of the medium-pressure feedwater pump 21 and the high-pressure feedwater pump 31 should not be clogged.
[0069] In summary, the combined cycle unit waste heat boiler blowdown system of this embodiment of the invention utilizes the makeup water pipe group and the second branch to solve the problem of poor water quality in the low-pressure steam drum 13, which causes clogging of the inlet filters of the medium-pressure feedwater pump 21 and the high-pressure feedwater pump 31 during the cold flushing stage. Furthermore, by separately arranging the main discharge pipe group and the bypass discharge pipe group, the pressure in the steam pipeline can be adjusted during the target plate replacement process, ensuring operational safety.
[0070] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0072] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0073] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0074] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0075] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. A combined cycle unit heat recovery steam generator blowpipe system, characterized by, include: A multi-stage steam supply system is provided, wherein the steam supply system is used to generate saturated steam using water as the working fluid. The multi-stage steam supply system includes a low-pressure steam supply system, a medium-pressure steam supply system, and a high-pressure steam supply system. The low-pressure steam supply system includes a condensate pump, a low-pressure economizer, a low-pressure steam drum, and a low-pressure superheater connected in sequence via pipelines. The medium-pressure steam supply system includes a medium-pressure feedwater pump, a medium-pressure economizer, a medium-pressure steam drum, and a medium-pressure superheater connected in sequence via pipelines. The high-pressure steam supply system includes a high-pressure feedwater pump, a high-pressure economizer, a high-pressure steam drum, and a high-pressure superheater connected in sequence via pipelines. The main discharge pipe assembly includes a main discharge header and a multi-stage main purging pipe connected to the main discharge header. The multi-stage main purging pipes correspond one-to-one with and are connected to the multi-stage steam supply devices. The main purging pipes are used to transport saturated steam generated by the corresponding steam supply devices and discharge it into the atmosphere through the main discharge header. The main purging pipes are equipped with main purging valves and target plates arranged at intervals from upstream to downstream in the steam flow direction. At least one bypass discharge pipe assembly, the bypass discharge pipe assembly including a bypass discharge main pipe and a multi-stage bypass purge pipe connected to the bypass discharge main pipe, the multi-stage bypass purge pipes corresponding one-to-one with the multi-stage main purge pipes, the connection between the bypass purge pipe and its corresponding main purge pipe being located upstream of the main purge valve in the steam flow direction, the bypass purge pipe being used to transport saturated steam in its corresponding main purge pipe and discharge it into the atmosphere through the bypass discharge main pipe, the bypass purge pipe being equipped with a bypass purge valve; The water supply pipe assembly includes a water supply main pipe and a first water supply sub-pipe and a second water supply sub-pipe connected to the water supply main pipe. The water supply main pipe is connected to the low-pressure steam drum, the first water supply sub-pipe is connected to the medium-pressure feedwater pump, and the second water supply sub-pipe is connected to the high-pressure feedwater pump. The second branch pipe is connected to the water supply main pipe and the pipeline between the condensate pump and the low-pressure economizer. The water supply main pipe is equipped with a first water supply valve. The connection between the second branch pipe and the water supply main pipe is located downstream of the first water supply valve in the steam flow direction. The second branch pipe is equipped with a second water supply valve.
2. The combined cycle unit heat recovery steam generator blowpipe system of claim 1, wherein, The multi-stage main line purging pipe includes a low-pressure main line purging pipe connected to the low-pressure steam supply device, a medium-pressure main line purging pipe connected to the medium-pressure steam supply device, and a high-pressure main line purging pipe connected to the high-pressure steam supply device. The multi-stage bypass purging pipe includes a low-pressure bypass purging pipe connected to the low-pressure main line purging pipe, a medium-pressure bypass purging pipe connected to the medium-pressure main line purging pipe, and a high-pressure bypass purging pipe connected to the high-pressure main line purging pipe.
3. The combined cycle unit heat recovery steam generator blowpipe system of claim 2, wherein, The low-pressure main purge pipe is connected to the low-pressure superheater.
4. The combined cycle unit heat recovery steam generator blowpipe system of claim 3, wherein, The medium-pressure main line purge pipe is connected to the medium-pressure superheater.
5. The combined cycle unit waste heat boiler blowing system according to claim 4, characterized in that, The high-pressure main purge pipe is connected to the high-pressure superheater. The high-pressure main purge pipe is also equipped with a high-pressure main steam valve, a reheater, and a medium-pressure main steam valve located upstream of the main purge valve on the high-pressure main purge pipe in the steam flow direction. The high-pressure main steam valve, the reheater, and the medium-pressure main steam valve are arranged at intervals from upstream to downstream in the steam flow direction. The combined cycle unit waste heat boiler purge system also includes a first branch pipe. The first branch pipe is connected to the medium-pressure main purge pipe and the high-pressure main purge pipe. The connection point between the first branch pipe and the medium-pressure main purge pipe is located upstream of the main purge valve on the medium-pressure main purge pipe in the steam flow direction. The connection point between the first branch pipe and the high-pressure main purge pipe is located between the high-pressure main steam valve and the reheater in the steam flow direction.
6. The combined cycle unit heat recovery steam generator blowpipe system of claim 5, wherein, The connection point between the high-pressure bypass purge pipe and the high-pressure main purge pipe is located upstream of the high-pressure main steam valve in the direction of steam flow.
7. The combined cycle unit heat recovery steam generator blowpipe system of claim 5, wherein, The medium-pressure bypass purging pipe is connected to the high-pressure main purging pipe, so that the medium-pressure bypass purging pipe is connected to the medium-pressure main purging pipe via the high-pressure main purging pipe and the first branch pipe.
8. The combined cycle unit heat recovery steam generator blowpipe system of claim 7, wherein, The connection between the medium-pressure bypass purge pipe and the high-pressure main purge pipe is located between the reheater and the medium-pressure main steam valve in the direction of steam flow.