Boiler water circulation system

Abstract

The utility model discloses a water circulation system of a boiler. The water circulation system comprises a distribution pipe, a heating pipe, a header, a steam pocket and a downcomer, a first outlet of the distribution pipe is connected with an inlet of the heating pipe; an outlet of the heating pipe is connected with a first inlet of the header, and feed water flows into the header through the distribution pipe and the heating pipe in sequence; an outlet of the header is connected with a first inlet of the steam pocket through a pipeline; the supplied water is heated in the collecting box to form a high-temperature water vapor mixture; the high-temperature water vapor mixture in the header enters the steam pocket through a pipeline; an outlet of the steam pocket is connected with an inlet of the downcomer, an outlet of the downcomer is connected with a second inlet of the header, and feed water enters the second inlet of the header through the downcomer. According to the utility model, the water supply circulation path of the boiler water circulation system when the unit is started is shortened, so that the heat loss in the water supply process is reduced, and the starting time of the unit is obviously reduced; and when the thermal power generating unit is started, the fire coal consumption and the fuel oil consumption are also reduced, and the starting cost is saved.

Description

Technical Field

[0001] The present application relates to the field of thermal power plant equipment, and in particular to a boiler water circulation system. Background Art

[0002] With the global push for renewable energy sources like wind and solar, the large-scale grid integration of renewable energy has significantly reduced the market share of thermal power generation, leading to a decline in the utilization rate of traditional coal-fired power units, particularly a significant reduction in generator hours. To meet the large-scale demand for renewable energy, thermal power generators must possess rapid start-up and shutdown capabilities and peak-shaving capabilities to adapt to grid demand.

[0003] Currently, load adjustment during startup of thermal power generators, particularly the operation of boiler water circulation systems, faces severe technical and safety challenges. During startup, existing boiler water circulation systems must sequentially pass water through multiple components, including the economizer, steam drum, and header. Due to the long circulation path, the water loses significant heat during the heating process, increasing startup time and energy consumption. Traditional systems suffer from low startup efficiency, which not only prolongs startup time but also increases coal and fuel consumption during startup, resulting in resource waste and environmental pressure. Summary of the Invention

[0004] In response to the above problems, the present application provides a boiler water circulation system, which shortens the water supply circulation path of the boiler water circulation system when the unit is started, thereby reducing the loss of water supply heat during the circulation process and significantly reducing the start-up time of the unit; as the start-up time of the unit is shortened, the amount of coal and fuel consumed when the thermal power unit is started is also significantly reduced, saving startup costs and enhancing the rapid start-up and shutdown capabilities of the thermal power unit.

[0005] To achieve the purpose of this application, this application provides the following technical solutions:

[0006] The present application provides a boiler water circulation system, comprising: a distribution pipe, a heating pipe, a header, a steam drum, and a downcomer;

[0007] The first outlet of the distribution pipe is connected to the inlet of the heating pipe; the outlet of the heating pipe is connected to the first inlet of the header, and the feed water flows into the header through the distribution pipe and the heating pipe in sequence;

[0008] The outlet of the header is connected to the first inlet of the steam drum through a pipe; the feed water is heated in the header to form a high-temperature water-steam mixture; the high-temperature water-steam mixture in the header enters the steam drum through the pipe;

[0009] The outlet of the steam drum is connected to the inlet of the downcomer, and the outlet of the downcomer is connected to the second inlet of the header; the feed water enters the second inlet of the header through the downcomer.

[0010] In a possible implementation, the heating pipe includes a furnace bottom heating main pipe and a furnace bottom heating pipe, and a branch pipe is connected between the furnace bottom heating main pipe and the furnace bottom heating pipe.

[0011] In a possible implementation, a furnace bottom heating valve is provided on the furnace bottom heating main pipe, and the furnace bottom heating valve is used to control the inflow and outflow of the feed water in the furnace bottom heating main pipe.

[0012] In one possible implementation, the system also includes a low-temperature economizer; the inlet of the low-temperature economizer is connected to the second outlet of the distribution pipe; a distribution pipe is connected between the outlet of the low-temperature economizer and the second inlet of the steam drum, and the low-temperature economizer is used to heat the feed water.

[0013] In a possible implementation, a feed water main regulating valve is provided on the distribution pipe before the inlet of the low-temperature economizer, and the feed water main regulating valve is used to control the inflow and outflow of the feed water in the low-temperature economizer.

[0014] In a possible implementation, the header includes a water-cooled wall upper header and a water-cooled wall lower header; the water-cooled wall upper header and the water-cooled wall lower header are connected via water-cooled wall tubes;

[0015] The first inlet of the water-cooled wall lower header is connected to the outlet of the heating pipe, the second inlet of the water-cooled wall lower header is connected to the outlet of the downcomer; the outlet of the water-cooled wall lower header is connected to the inlet of the water-cooled wall upper header;

[0016] The outlet of the water-cooled wall upper header is connected to the outlet of the steam drum.

[0017] In a possible implementation, the downcomers include at least two, a distributor is separately provided at the lower end of each downcomer, and an inlet pipe is connected between each distributor and the header.

[0018] In one possible implementation, a separator and a dryer are provided in the steam drum;

[0019] The separator is provided at the lower part of the steam drum, and is used to separate the high-temperature water vapor mixture; the separated water flows into the downcomer;

[0020] The dryer is located at the upper portion of the steam drum, and dries the separated steam.

[0021] In a possible implementation, the water-cooled wall tubes are composed of 648 tubes with an outer diameter of 60 mm, a wall thickness of 7 mm, a material of SA210-C, and a pitch of 76 mm.

[0022] In a possible implementation, the downcomer is a large-diameter downcomer, which is used to increase the water supply flow rate and reduce flow resistance, and the specific diameter is 533 mm.

[0023] This utility model provides a boiler water circulation system. During unit startup, feedwater flows directly into the header through a heating pipe, shortening the feedwater circulation path, thereby reducing heat loss in the feedwater circulation path and improving the unit's startup efficiency. This shortened feedwater circulation path significantly reduces unit startup time. Simultaneously, coal and fuel consumption during thermal power unit startup is also reduced, saving startup costs and improving the unit's economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application.

[0025] Figure 1 This is a system schematic diagram of a boiler water circulation system provided by the utility model.

[0026] Reference numerals:

[0027] 1. Distribution pipe; 1-1. Feedwater main regulating valve; 1-2. Feedwater bypass valve; 2. Heating pipe; 2-1. Bottom heating main pipe; 2-2. Bottom heating pipe; 2-3. Branch pipe; 2-4. Bottom heating valve; 3. Header; 3-1. Water-cooled wall lower header; 3-2. Water-cooled wall upper header; 3-3. Water-cooled wall tube; 4. Steam drum; 5. Downcomer; 6. Low-temperature economizer; 7. Steam-water outlet pipe. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0029] 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 quantity of the technical features indicated. Thus, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of this application, unless otherwise specified, "plurality" means two or more.

[0030] With the global push for renewable energy sources like wind and solar, the large-scale grid integration of renewable energy has significantly reduced the market share of thermal power generation, leading to a decline in the utilization rate of traditional coal-fired power units, particularly a significant reduction in generator hours. To meet the large-scale demand for renewable energy, thermal power generators must possess rapid start-up and shutdown capabilities and peak-shaving capabilities to adapt to grid demand.

[0031] Currently, load adjustment during the startup of thermal power generators, particularly the operation of boiler water circulation systems, faces severe technical and safety challenges. This utility model provides a boiler water circulation system designed to address existing issues during the startup of thermal power generators, such as long feedwater circulation paths, high heat loss, long startup times, and energy waste. The technical solution of this utility model effectively shortens the feedwater path of the boiler water circulation system, reduces heat loss, significantly improves unit startup efficiency, and reduces coal and fuel consumption.

[0032] The following describes the boiler water circulation system of the utility model embodiment with reference to the accompanying drawings. Figure 1 As shown, the utility model provides a boiler water circulation system including a distribution pipe 1, a heating pipe 2, a header 3, a steam drum 4 and a downcomer 5.

[0033] The first outlet of the distribution pipe 1 is connected to the inlet of the heating pipe 2; the outlet of the heating pipe 2 is connected to the first inlet of the header 3, and the water flows into the header 3 through the distribution pipe 1 and the heating pipe 2 in sequence;

[0034] The outlet of the header 3 is connected to the first inlet of the steam drum 4 through a pipe; the feed water is heated in the header 3 to form a high-temperature water-steam mixture; the high-temperature water-steam mixture in the header 3 enters the steam drum 4 through the pipe;

[0035] The outlet of the steam drum 4 is connected to the inlet of the downcomer 5 , and the outlet of the downcomer 5 is connected to the second inlet of the header 3 ; the feed water enters the second inlet of the header 3 through the downcomer 5 .

[0036] In the embodiment of the present application, the boiler water circulation system optimizes the layout and connection of each component, specifically, the distribution pipe 1 is connected to the heating pipe 2, the heating pipe 2 is connected to the header 3, the header 3 is connected to the steam drum 4, and the steam drum 4 is connected to the header through the downcomer 5, thereby forming a complete circulation path for the feed water. The following describes in detail the circulation path of the feed water: the feed water first flows into the heating pipe 2 from the first outlet of the distribution pipe 1, and then enters the first inlet of the header 3 through the heating pipe 2. The feed water then enters the header 3 and is heated to form a high-temperature water vapor mixture. The high-temperature water vapor mixture is a mixture of steam and water. After that, the high-temperature water vapor mixture is introduced into the steam drum 4 through a pipeline. The high-temperature water vapor mixture in the steam drum 4 is separated into steam and water by a separator. Finally, the separated water enters the second inlet of the header 3 through the downcomer 5.

[0037] Compared to existing technologies, the boiler water circulation system provided in this embodiment shortens the feedwater circulation path by optimizing the layout and connections of various components, reducing heat loss during the feedwater circulation path, thereby significantly improving the efficiency of the boiler startup process. This shortened feedwater circulation path significantly reduces unit startup time; At the same time, coal and fuel consumption during thermal power unit startup are also reduced, saving startup costs and improving the unit's economic benefits.

[0038] Specifically, Table 1 lists the performance comparison data of the boiler water circulation system when different startup paths are adopted. It can be seen from the data that the boiler water circulation system of the present invention greatly shortens the startup time and significantly reduces the consumption of coal and fuel oil. The specific analysis is as follows: On April 20, the system adopted the traditional water supply circulation path, the startup time was 5.5 hours, the coal consumption was 44 tons, and the fuel consumption was 14.3 tons. On July 20, the system adopted the improved path of this embodiment, the startup time was only 2 hours, the coal consumption was reduced to 22.47 tons, and the fuel consumption was also reduced to 5.5 tons. It can be seen that the boiler water circulation system provided by this embodiment has shortened the startup time by about 60%, reduced the coal consumption by about 50%, and reduced the fuel consumption by about 60%. In addition, due to the reduction of heat loss, the system further improves the startup efficiency of the unit and adapts to the operation requirements of rapid start and stop and peak regulation.

[0039] date April 20 July 20 Drum wall temperature 22.5℃ 30℃ Ignition time 8:00 10:30 Drum wall temperature at ignition 90.8℃ 123℃ Coal consumption 44t 22.47t Fuel quantity 14.3t 5.5t Turn time 13:30 12:30 Ignition to run time 5.5 hours 2 hours

[0040] Table 1

[0041] In a possible embodiment, the heating pipe 2 includes a furnace bottom heating main pipe 2-1 and a furnace bottom heating pipe 2-2, and a branch pipe 2-3 is connected between the furnace bottom heating main pipe 2-1 and the furnace bottom heating pipe 2-2.

[0042] The furnace bottom heating main pipe 2-1 and furnace bottom heating pipes 2-2 are components of the heating and circulation system in a thermal power plant. The furnace bottom heating main pipe 2-1 is the main pipeline responsible for delivering feed water. It distributes feed water to the furnace bottom heating pipes 2-2 via branch pipes 2-3. Furnace bottom heating pipes 2-2 are installed at the bottom of the boiler. Circulating heating maintains the furnace bottom temperature within a certain range, ensuring normal boiler operation and combustion efficiency.

[0043] It should be noted that the furnace bottom heating tube 2-2 is formed by multiple sub-tubes. The number of furnace bottom heating tubes 2-2 is determined according to the boiler design and heat load requirements. The furnace bottom heating tubes 2-2 can be arranged in multiple layers or a single layer to ensure sufficient heat transfer area. The furnace bottom heating tubes 2-2 can be arranged in multiple tube bundles, each consisting of a number of tubes, with 48, 96, or even more tubes forming the furnace bottom heating tubes 2-2. The furnace bottom heating tubes 2-2 can also be arranged in a serpentine coil or spiral coil arrangement.

[0044] In a possible implementation manner, a furnace bottom heating valve 2-4 is provided on the furnace bottom heating main pipe 2-1, and the furnace bottom heating valve 2-4 is used to control the inflow and outflow of feed water in the furnace bottom heating main pipe 2-1.

[0045] In the embodiment of the present application, after the furnace bottom heating valve 2-4 is opened, the feed water can be controlled to flow into the first inlet of the header 3 through the furnace bottom heating main pipe 2-1. After the furnace bottom heating valve 2-4 is closed, the feed water can be controlled not to flow into the furnace bottom heating main pipe 2-1, thereby controlling the switching of the feed water circulation path after the unit is successfully started.

[0046] Optionally, a stop valve and a check valve may be provided on the furnace bottom heating main pipe 2-1 and the furnace bottom heating pipe 2-2. The stop valve is used to control the start and stop of the system; the check valve is used to prevent the feed water from flowing back into the distribution pipe 1.

[0047] In a possible embodiment, the boiler water circulation system also includes a low-temperature economizer 6, the inlet of the low-temperature economizer 6 is connected to the second outlet of the distribution pipe 1, and the distribution pipe 1 is connected between the outlet of the low-temperature economizer 6 and the second inlet of the steam drum 4. The low-temperature economizer 6 is used to heat the feed water.

[0048] In an embodiment of the present application, another circulation path for feed water in the boiler water circulation system is provided, and this circulation path needs to be switched to after the unit is successfully started. The specific circulation path of the feed water is: the feed water first flows into the low-temperature economizer 6 from the second outlet of the distribution pipe 1, and then enters the steam drum 4 through the distribution pipe 1, and then flows out of the downcomer 5 from the outlet of the steam drum 4, and the feed water is mixed with the boiler water in the boiler in the downcomer 5. Then the feed water enters the second inlet of the header 3 through the downcomer 5. After the feed water enters the header 3 and is heated, a high-temperature water vapor mixture is formed. The high-temperature water vapor mixture is a mixture containing steam and water. The high-temperature water vapor mixture is introduced into the steam drum 4 through the pipe 7. The high-temperature water vapor mixture in the steam drum 4 is separated into steam and water by the separator, and the separated water enters the second inlet of the header 3 through the downcomer 5. The use of this circulation path can ensure the normal operation requirements after the unit is started.

[0049] Among them, the low-temperature economizer 6 is a heat recovery device that heats the feed water by absorbing the waste heat in the exhaust gas at the tail end of the boiler, thereby ensuring the overall thermal efficiency of the boiler water circulation system when the unit is operating normally.

[0050] In a possible embodiment, a feed water main regulating valve 1 - 1 is provided on the distribution pipe 1 before the inlet of the low-temperature economizer 6 , and the feed water main regulating valve 1 - 1 is used to control the inflow and outflow of feed water in the low-temperature economizer 6 .

[0051] In the embodiment of the present application, when the unit is started, the feed water main regulating valve 1-1 is closed to control the feed water not to flow into the low-temperature economizer 6. After the unit is successfully started, the feed water main regulating valve 1-1 is opened to control the feed water to flow into the low-temperature economizer 6.

[0052] Optionally, a water supply bypass valve 1-2 may be provided on the distribution pipe 1, and the water supply bypass valve 1-2 is connected in parallel with the water supply main regulating valve 1-1. The water supply bypass valve 1-2 has two functions. On the one hand, when the water supply main regulating valve 1-1 fails or requires maintenance, the water supply in the boiler water circulation system can be maintained by opening the water supply bypass valve 1-2 to ensure that the system can still operate normally. On the other hand, the adjustment range of the water supply bypass valve 1-2 is finer than that of the water supply main regulating valve 1-1. When the water supply demand is low during low-load operation of the unit, the water supply can be adjusted at a small flow rate by opening the water supply bypass valve 1-2 to ensure fine-tuning and precise control of the boiler water level.

[0053] In an embodiment of the present application, in order to ensure the normal needs of the unit after the unit is successfully started, the feed water main regulating valve 1-1 can be switched on to allow the feed water to flow through the low-temperature economizer 6, the steam drum 4 and the header 3 in sequence. At this time, there are two circulation paths for the feed water in the boiler water circulation system, one is the circulation path when the unit is started, that is, the feed water flows through the heating tube 2, the header 3, and the steam drum 4 in sequence, and the other is the circulation path after the unit is successfully started, that is, the feed water flows through the low-temperature economizer 6, the steam drum 4 and the header 3 in sequence. The combination of these two circulation paths allows the boiler water circulation system to not only start quickly when the unit is started, but also provide higher conversion efficiency after startup, thereby ensuring the normal operation of the unit. The feed water main regulating valve 1-1 and the furnace bottom heating valve 2-4 in the above embodiment can be used to control the switching of the two circulation paths. The specific switching process is as follows:

[0054] First, when the unit is started, close the main water supply valve 1-1 and open the furnace bottom heating valve 2-4.

[0055] Then, after the unit is successfully started, open the water supply main regulating valve 1-1 and close the furnace bottom heating valve 2-4.

[0056] The above switching process controls the two circulation paths of the water supply, which is convenient and simple.

[0057] In one possible embodiment, the header 3 includes a water-cooled wall lower header 3-1 and a water-cooled wall upper header 3-2; the water-cooled wall lower header 3-1 and the water-cooled wall upper header 3-2 are connected via a water-cooled wall tube 3-3; the first inlet of the water-cooled wall lower header 3-1 is connected to the outlet of the heating tube 2, and the second inlet of the water-cooled wall lower header 3-1 is connected to the outlet of the downcomer 5; the outlet of the water-cooled wall lower header 3-1 is connected to the inlet of the water-cooled wall upper header 3-2; and the outlet of the water-cooled wall upper header 3-2 is connected to the outlet of the steam drum 4.

[0058] In this embodiment, the upper water wall header 3-2 is located at the top or upper portion of the boiler and collects water or steam from the water wall tubes 3-3. The lower water wall header 3-1, located at the bottom of the boiler, distributes water from the boiler's water circulation system to each water wall tube 3-3, ensuring even water flow to each tube. The water wall tubes 3-3 absorb radiant heat generated by combustion within the boiler furnace, heating the feed water until it becomes a high-temperature water-steam mixture.

[0059] In a possible embodiment, the downcomers 5 include at least two, a distributor is separately provided at the lower end of each downcomer 5 , and an inlet pipe is connected between each distributor and the header 3 .

[0060] In the embodiment of the present application, the distributor reintroduces the feed water into the second inlet of the header 3 through the inlet pipe, thus completing a cycle. This design ensures uniform distribution of the feed water in the downcomer 5, reduces the unevenness of the water flow, and improves the water circulation efficiency.

[0061] In one possible embodiment, a separator and a dryer are provided in the steam drum 4; the separator is provided at the lower part of the steam drum 4, and is used to separate the high-temperature water vapor mixture; the separated water flows into the downcomer 5; the dryer is located at the upper part of the steam drum 4, and the dryer dries the separated steam.

[0062] In the embodiments of the present application, specifically, the separator can be an axial-flow cyclone separator, and the dryer can be a vertical corrugated dryer. The separator is located below the steam drum 4. The axial-flow cyclone separator generates centrifugal force through its internal rotation, which is used to efficiently separate the high-temperature water-steam mixture entering the steam drum 4. After separation, water and steam are formed. The separated water flows into the downcomer 5 through gravity and continues to participate in the steam-water cycle. The dryer is located above the steam drum 4. The vertical corrugated dryer further dries the separated steam to form dry steam through the corrugated surface. The dry steam then enters the next stage of equipment.

[0063] In a possible implementation manner, the water-cooled wall tube 3 - 3 is composed of 648 tubes with an outer diameter of 60 mm, a wall thickness of 7 mm, a material of SA210-C, and a pitch of 76 mm.

[0064] In actual use, the shape of the water-cooled wall tubes 3-3 can be designed differently based on the boiler's heat transfer requirements and furnace structure. Optionally, the water-cooled wall tubes 3-3 can be divided into 32 circulation loops based on the heat exposure. Alternatively, round water-cooled wall tubes can be used, as they have excellent mechanical strength and pressure resistance, and can withstand higher operating pressures and temperatures. Alternatively, flat water-cooled wall tubes can be used when a larger area of ​​heat transfer is required or when the piping is arranged compactly. Flat water-cooled wall tubes increase the surface area of ​​the water-cooled wall tubes, improving contact with the furnace flame and enhancing heat transfer.

[0065] In a possible embodiment, the downcomer 5 is a large-diameter downcomer for increasing the water flow rate and reducing the flow resistance, and the specific diameter is 533 mm.

[0066] In this embodiment, the downcomer 5 connecting the steam drum and the header is a large-diameter downcomer. This ensures sufficient water in the water-wall tubes 3-3 of the header 3 to absorb the heat generated by the furnace and ensures smooth steam-water circulation within the boiler. This effectively balances the water flow in the water-wall tubes 3-3 and ensures uniform heat transfer. This plays a crucial role in maintaining stable boiler operation and preventing overheating.

[0067] The working principle of the utility model boiler water circulation system is as follows:

[0068] During unit startup, feedwater is controlled to flow from the first outlet of distribution pipe 1 into the furnace bottom heating main pipe 2-1 by closing the main feedwater regulating valve 1-1 and the bypass feedwater valve 1-2 and opening the furnace bottom heating valve 2-4. The furnace bottom heating main pipe 2-1 distributes the feedwater to the furnace bottom heating tubes 2-2 via branch pipes 2-3. The feedwater enters the furnace bottom heating tubes 2-2 through the water-cooled wall lower header 3-1. Once in this lower header 3-1, the feedwater is distributed to each bundle of water-cooled wall tubes 3-3. The feedwater in the bundles continuously absorbs heat energy and is then collected through the water-cooled wall tubes 3-3 into the upper water-cooled wall header 3-2. The feedwater is continuously heated to form a high-temperature water-steam mixture, which is then introduced into the steam drum 4 via the steam-water outlet pipe 7. The separator is located below the steam drum 4. The high-temperature water-steam mixture first enters the separator, where it efficiently separates the water from the mixture, forming water and steam. The separated water flows by gravity into the downcomer 5, continuing its steam-water cycle. The dryer, located above the steam drum 4, further dries the separated steam to form dry steam, which then enters the next stage of equipment.

[0069] The feed water circulates continuously in the above process until the unit is successfully started, and then the feed water circulation path is switched to control the feed water to flow into the steam drum 4 through the low-temperature economizer 6.

[0070] The specific switching method is: open the water supply main regulating valve 1-1 and the water supply bypass valve 1-2, and close the furnace bottom heating valve 2-4.

[0071] The boiler water circulation workflow after switching is:

[0072] Feedwater flows from the second outlet of distribution pipe 1 into the low-temperature economizer 6, then enters the drum 4 through distribution pipe 1, which is arranged along the length of the drum 4. Once inside, the feedwater flows into the downcomer 5. Because boiler water from the previous circulation path is present in the downcomer 5, the feedwater and boiler water mix in the downcomer 5. This system features four downcomers 5, each with a distributor at its lower end. These distributors connect to 96 inlet pipes, which deliver the feedwater into the lower waterwall header 3-1. After entering the lower waterwall header 3-1, the feedwater is distributed to each bundle of waterwall tubes 3-3. The feedwater in the bundles continuously absorbs heat energy and is then collected by the waterwall tubes 3-3 into the upper waterwall header 3-2. The feedwater is continuously heated to form a high-temperature water-steam mixture, which is then introduced into the drum 4 via the steam-water outlet pipe 7. The separator is located below the steam drum 4. The high-temperature water-steam mixture first enters the separator, where it efficiently separates the water from the mixture, forming water and steam. The separated water flows by gravity into the downcomer 5, continuing its steam-water cycle. The dryer, located above the steam drum 4, further dries the separated steam to form dry steam, which then enters the next stage of equipment.

[0073] The above-mentioned boiler water circulation system can easily cope with the start-up and shutdown peak regulation of the unit. Through the control of the valve, the feed water can flow through two different circulation paths during startup and normal operation, which not only ensures the rapid start-up of the unit, but also meets the needs during normal operation.

[0074] The utility model provides a boiler water circulation system, which has the following beneficial effects:

[0075] 1. When the unit is started, the water supply circulation path is short, which shortens the water supply circulation path, reduces heat loss, reduces the unit start-up time, and significantly improves the unit start-up efficiency; at the same time, it reduces the amount of coal and fuel burned when the unit is started, saves startup costs, and improves the economic benefits of the unit.

[0076] 2. The feed water can flow through two different circulation paths during startup and normal operation, which not only ensures the rapid startup of the unit but also meets the needs during normal operation.

[0077] In the several embodiments provided in this application, it should be understood that the disclosed systems, modules and methods can be implemented in other ways. For example, the module embodiments described above are only schematic. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of modules or units, which can be electrical, mechanical or other forms.

[0078] The above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit them. The present application is not limited to the precise structures described above and illustrated in the accompanying drawings, and it cannot be assumed that the specific implementation of the present application is limited to these descriptions. For those skilled in the art of the present application, any changes and modifications made without departing from the concept of the present application should be deemed to fall within the scope of protection of the present application.

Claims

1. A boiler water circulation system, characterized in that: include: Distribution pipes, heating pipes, headers, steam drums and downcomers; The first outlet of the distribution pipe is connected to the inlet of the heating pipe; the outlet of the heating pipe is connected to the first inlet of the header, and the feed water flows into the header through the distribution pipe and the heating pipe in sequence; The outlet of the header is connected to the first inlet of the steam drum through a pipe; the feed water is heated in the header to form a high-temperature water-steam mixture; the high-temperature water-steam mixture in the header enters the steam drum through the pipe; The outlet of the steam drum is connected to the inlet of the downcomer, the outlet of the downcomer is connected to the second inlet of the header, and the feed water enters the second inlet of the header through the downcomer.

2. The boiler water circulation system according to claim 1, characterized in that: The heating pipes include a furnace bottom heating main pipe and furnace bottom heating pipes, and branch pipes are connected between the furnace bottom heating main pipe and the furnace bottom heating pipes.

3. The boiler water circulation system according to claim 2, characterized in that: The furnace bottom heating main pipe is provided with a furnace bottom heating valve, and the furnace bottom heating valve is used to control the inflow and outflow of the feed water in the furnace bottom heating main pipe.

4. The boiler water circulation system according to claim 1, characterized in that: The system also includes a low-temperature economizer; the inlet of the low-temperature economizer is connected to the second outlet of the distribution pipe; a distribution pipe is connected between the outlet of the low-temperature economizer and the second inlet of the steam drum, and the low-temperature economizer is used to heat the feed water.

5. The boiler water circulation system according to claim 4, characterized in that: A feed water main regulating valve is provided on the distribution pipe before the inlet of the low-temperature economizer, and the feed water main regulating valve is used to control the inflow and outflow of the feed water in the low-temperature economizer.

6. The boiler water circulation system according to claim 1, characterized in that: The headers include an upper water-cooled wall header and a lower water-cooled wall header; the upper water-cooled wall header and the lower water-cooled wall header are connected via water-cooled wall tubes; The first inlet of the water-cooled wall lower header is connected to the outlet of the heating pipe, the second inlet of the water-cooled wall lower header is connected to the outlet of the downcomer; the outlet of the water-cooled wall lower header is connected to the inlet of the water-cooled wall upper header; The outlet of the water-cooled wall upper header is connected to the outlet of the steam drum.

7. The boiler water circulation system according to claim 1, characterized in that: The downcomer comprises at least two, and a distributor is independently provided at the lower end of each downcomer, and an inlet pipe is connected between each distributor and the header.

8. The boiler water circulation system according to claim 1, characterized in that: A separator and a dryer are provided in the steam drum; The separator is provided at the lower part of the steam drum, and is used to separate the high-temperature water vapor mixture; the separated water flows into the downcomer; The dryer is located at the upper portion of the steam drum, and dries the separated steam.

9. The boiler water circulation system according to claim 6, characterized in that: The water-cooled wall tubes are composed of 648 tubes with an outer diameter of 60 mm, a wall thickness of 7 mm, a material of SA210-C, and a pitch of 76 mm.

10. The boiler water circulation system according to claim 1, characterized in that: The downcomer is a large-diameter downcomer used to enhance the water supply flow and reduce flow resistance, and the specific diameter is 533 mm.

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