A boiler bypass system capable of extracting steam in large proportion and a boiler using the system

Abstract

The present invention proposes a bypass system for a boiler capable of extracting steam in a large proportion and a boiler using the system, belonging to the technical field of boiler manufacturing and modification. It solves the problem that steam extraction has a great impact on boiler operation, and that the steam turbine of an existing power plant needs to be extensively modified when extracting steam, and the steam turbine after the modification cannot adapt well to steam extraction and non-steam extraction conditions. It includes a bypass flue gas pipeline and a steam extraction pipeline. The bypass flue gas pipeline is connected in parallel with the original boiler flue gas pipeline. The inlet of the steam extraction pipeline is connected to the original boiler water supply main line, and the outlet is connected to the external steam supply pipeline. The water is arranged around the bypass flue gas pipeline and flows through the original boiler area to be treated by the original boiler water quality treatment system. It is mainly used to achieve the decoupling of the boiler steam extraction process and the normal steam production process of the boiler, and reduce the impact of steam extraction on boiler operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of boiler manufacturing and modification, and in particular relates to a boiler bypass system capable of extracting steam in a large proportion and a boiler using the system. Background Art

[0002] In recent years, to improve the profitability of thermal power plants, superheated steam has been frequently extracted from boilers to meet industrial production needs. Extracting reheated steam significantly impacts the steam turbine, reducing the amount of reheated steam and resulting in insufficient reheater cooling capacity, posing safety risks. This is particularly acute under low load conditions. Boilers cannot achieve a high, constant extraction rate, and in existing power plants, extracting steam requires extensive turbine modifications. These modifications cannot effectively adapt to both extraction and non-extraction conditions. Summary of the Invention

[0003] In view of this, in order to solve the problem that steam extraction has a significant impact on boiler operation, and that existing power plants require extensive steam turbine modifications when extracting steam, and that the modified steam turbines cannot adapt well to steam extraction and non-steam extraction conditions, the present invention proposes a boiler bypass system that can extract steam in a large proportion, and a boiler using this system. By opening a bypass flue to increase the evaporation heating surface of the flue gas, the economizer and superheater inside the system are used to form a steam extraction pipeline to produce steam for external demand, thereby decoupling the steam extraction process from the normal steam production process of the boiler, reducing the impact of steam extraction on boiler operation, and being able to adapt to various operating conditions with different external steam extraction requirements.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions: a boiler bypass system capable of extracting a large proportion of steam, comprising a bypass flue gas pipeline and a steam extraction pipeline. The bypass flue gas pipeline is connected in parallel with the original boiler flue gas pipeline. The inlet of the steam extraction pipeline is connected to the original boiler feed water main line, and the outlet is connected to the external steam supply pipeline. The steam extraction pipeline is arranged around the bypass flue gas pipeline and flows through the original boiler area to be treated by the original boiler water quality treatment system.

[0005] The bypass flue gas pipeline includes a bypass inlet flue, a bypass flue and a bypass outlet flue that are connected in sequence. A bypass flue temperature regulating baffle is provided at the connection between the bypass flue and the bypass outlet flue to adjust the flue gas flow rate. The bypass inlet flue and the bypass outlet flue are connected to the original boiler flue gas pipeline. A bypass economizer and a bypass superheater are provided in the bypass flue, and the bypass economizer is arranged below the bypass superheater.

[0006] The steam extraction pipeline includes a bypass regulating valve, a bypass economizer, an original boiler area, a bypass superheater regulating valve and a bypass superheater which are connected in sequence. The heat relied on by the steam extraction pipeline to generate steam comes from the bypass economizer and the bypass superheater.

[0007] Furthermore, the steam extraction pipeline also includes a water spray desuperheater, which is arranged between the bypass superheater and the outlet of the steam extraction pipeline.

[0008] Furthermore, the bypass flue temperature regulating baffle is made of stainless steel.

[0009] Furthermore, the bypass economizer is a stainless steel economizer.

[0010] Furthermore, the bypass regulating valve and the bypass superheater regulating valve are both pneumatic regulating valves.

[0011] Furthermore, the bypass superheater is a convection superheater.

[0012] A boiler is provided with a water treatment system and a bypass system capable of extracting a large proportion of steam from the above-mentioned boiler. The steam extraction pipeline flows through the working area of ​​the water treatment system.

[0013] Furthermore, the boiler is a circulating fluidized bed (CFB) boiler, the water quality treatment system acts on the furnace water-cooled wall and the wall-wrapped superheater, and the steam extraction pipeline flows through the furnace water-cooled wall and the wall-wrapped superheater for water quality treatment.

[0014] Compared with the prior art, the bypass system for extracting steam in a large proportion and the boiler using the system described in the present invention have the following beneficial effects:

[0015] 1. The present invention has a simple structure and is easy to modify and install. By connecting a bypass flue in parallel with the original boiler flue, the heat exchange area with the flue gas is increased. The size of the heating surface of the original boiler remains unchanged. The economizer utilizes the increased heat exchange area to absorb heat, and then cooperates with the superheater to produce steam for external demand extraction, thereby achieving decoupling of the steam extraction process from the normal steam production process of the boiler, reducing the impact of steam extraction on boiler operation.

[0016] 2. The present invention utilizes the water treatment system of the original boiler to adjust the water quality, thereby extending the service life of the steam extraction pipeline.

[0017] 3. The present invention adjusts the flow in the bypass flue and the flow in the steam extraction pipe by cooperating with components such as the flue temperature regulating baffle and the valve, so as to adapt to different steam extraction needs.

[0018] 4. The steam extraction pipeline of the present invention is also provided with a water spray desuperheater. When the requirements for adjusting the quality of the extracted steam exceed the adjustment capacity of the flue damper, the water spray desuperheater is used to reduce the steam temperature, thereby further improving the adjustment capacity and adaptability of the device.

[0019] 5. The present invention optimizes the types and materials of components according to the working environment. The use of stainless steel can significantly increase the service life of the components. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 Schematic diagram of the main structure of the bypass system of the present invention;

[0022] Figure 2 This is a connection diagram of the steam extraction pipeline of the bypass system of the present invention;

[0023] Figure 3 A connection diagram for adding a water spray desuperheater to the steam extraction pipeline of the bypass system of the present invention;

[0024] Figure 4 Schematic diagram of the main structure of a CFB boiler equipped with the bypass system of the present invention;

[0025] Figure 5 This is a schematic diagram of the main structure of a CFB boiler;

[0026] Figure 6 This is the connection diagram of the main feed water line of the CFB boiler;

[0027] Figure 7 This is a connection diagram of the steam extraction pipeline of the bypass system of the present invention and the main water supply line of the CFB boiler;

[0028] In the figure: 1-bypass inlet flue; 2-bypass flue; 3-bypass outlet flue; 4-bypass flue temperature control damper; 5-bypass regulating valve; 6-bypass economizer; 7-original boiler area; 8-bypass superheater regulating valve; 9-bypass superheater; 10-water spray desuperheater; 11-main line regulating valve; 12-main line economizer; 13-low-temperature superheater; 14-medium-temperature superheater; 15-high-temperature superheater; 71-furnace water-cooled wall; 72-wall-wrapped superheater. DETAILED DESCRIPTION

[0029] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features therein can be combined with each other in the absence of conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0030] Specific implementation method 1, see Figure 1-7To illustrate this embodiment, a bypass system for extracting steam from a boiler in a large proportion comprises a bypass flue gas pipeline and a steam extraction pipeline. The bypass flue gas pipeline is connected in parallel with the original boiler flue gas pipeline. The inlet of the steam extraction pipeline is connected to the original boiler feed water main line, and the outlet is connected to the external steam supply pipeline. The steam extraction pipeline is arranged around the bypass flue gas pipeline and flows through the original boiler area 7 to be treated by the original boiler water quality treatment system.

[0031] The bypass flue gas pipeline includes a bypass inlet flue 1, a bypass flue 2 and a bypass outlet flue 3 connected in sequence. A bypass flue temperature regulating baffle 4 is provided at the connection between the bypass flue 2 and the bypass outlet flue 3 for regulating the flue gas flow rate. The bypass inlet flue 1 and the bypass outlet flue 3 are connected to the original boiler flue gas pipeline. A bypass economizer 6 and a bypass superheater 9 are provided in the bypass flue 2, and the bypass economizer 6 is arranged below the bypass superheater 9.

[0032] The steam extraction pipeline includes a bypass regulating valve 5, a bypass economizer 6, an original boiler area 7, a bypass superheater regulating valve 8 and a bypass superheater 9 which are connected in sequence. The heat relied on by the steam extraction pipeline to generate steam comes from the bypass economizer 6 and the bypass superheater 9.

[0033] The present invention provides a bypass flue gas pipeline and a steam extraction pipeline. Since there is a surplus in the boiler flue gas heating surface, the bypass flue gas pipeline acts as an increased heating surface. The increased heating surface cooperates with the bypass economizer 6 in the bypass flue gas pipeline and the bypass superheater 9 to produce steam for external demand. The amount of steam extraction can be flexibly changed under any load of the boiler without affecting the parameters of the main line, thus achieving decoupling from the main heating surface. The newly added heating surface for steam extraction is arranged in an independent flue, in parallel with the main line of the boiler. The economizer is the evaporation heating surface, and the superheater is the superheating heating surface. The steam and flue gas volumes of the superheater can be flexibly adjusted, thereby achieving large-scale flexible adjustment of the total amount of steam extraction and parameters. The bypass economizer increases the evaporation heating surface, and its heat absorption is flexibly adjustable, reducing the amount of coal added for steam extraction and the amount of flue gas added during steam extraction. The heat absorption ratio between the economizer and superheater is the same as that of the boiler's economizer and superheater. This ensures that the heat absorption ratio of the boiler's evaporation and superheating heating surfaces remains constant regardless of whether flue gas is added or removed from the newly added flue. This ensures that the boiler's main steam parameters remain unchanged even when the steam extraction rate changes, reducing the impact of the steam extraction process on the normal operation of the boiler. Simultaneously, the water quality in the steam extraction pipeline is treated by means of the original boiler's water treatment system, preventing damage to the steam extraction pipeline from scale, corrosion, and impurities, thereby extending the service life of the steam extraction pipeline, improving thermal efficiency, and reducing operating costs. Although the steam flows through a portion of the original boiler, the heat generated by the steam extraction pipeline primarily comes from the bypass economizer 6 and bypass superheater 9. Therefore, it does not absorb a large amount of heat from the original boiler, and has little impact on the normal operation of the original boiler.

[0034] The steam extraction pipeline described herein also includes a water spray desuperheater 10, disposed between the bypass superheater 9 and the outlet of the steam extraction pipeline. The water spray desuperheater 10 is simple in structure and compact in size, making it easy to install and maintain. When the externally demanded steam temperature decreases and the steam temperature generated by the steam extraction pipeline becomes too high, the water spray desuperheater 10 can quickly adjust the steam temperature to accommodate the load change, achieving precise steam temperature regulation.

[0035] The bypass flue temperature regulating baffle 4 described in this application is made of stainless steel.

[0036] The bypass economizer 6 described in this application is a stainless steel economizer.

[0037] The present invention takes into account that boiler flue gas often contains corrosive components such as sulfides and chlorides. Stainless steel can effectively resist the erosion of these corrosive media. The acidic gas in the flue gas is easily condensed to form acid liquid. Stainless steel can also effectively resist this acid corrosion, effectively extending the life of the equipment, improving operational reliability and reducing long-term costs.

[0038] The bypass control valve 5 and the bypass superheater control valve 8 described herein are both pneumatic control valves. Pneumatic control valves can quickly respond to changes in control signals, ensuring precise control of steam flow. Pneumatic control valves are highly adaptable to environmental conditions such as temperature and humidity, and can operate stably under a wide range of operating conditions, making them particularly suitable for use in boiler environments.

[0039] The bypass superheater 9 described in this application is a convection superheater. The convection superheater has a simple structure, strong adaptability, and can adjust the steam temperature according to load changes to ensure the stability of steam parameters.

[0040] The boiler described in the present application is provided with a water treatment system and a bypass system for extracting a large proportion of steam from the boiler as described above, wherein the steam extraction pipeline flows through the active area of ​​the water treatment system.

[0041] The boiler described in the present application is a CFB boiler. The water quality treatment system acts on the furnace water-cooled wall 71 and the wall-wrapped superheater 72. The steam extraction pipeline flows through the furnace water-cooled wall 71 and the wall-wrapped superheater 72 for water quality treatment. After the flue gas exchanges heat with the heating surface in the original boiler flue and the bypass flue, it is gathered into one path to enter the main economizer and the air preheater. A flue gas bypass is opened in the CFB boiler for steam extraction. By utilizing the flue gas bypass system, the operating parameters of the boiler can be flexibly adjusted to improve the efficiency and reliability of the system. The flue gas bypass system controls the amount of flue gas entering the bypass flue through the flue gas temperature regulating baffle of the CFB boiler and the temperature regulating baffle of the bypass flue. At the same time, it controls the water volume of the bypass economizer by controlling the opening of the bypass regulating valve, and controls the flue gas temperature at the bypass flue outlet, thereby controlling the steam temperature and pressure to adapt to different load requirements. The flue gas bypass system can quickly adjust the steam parameters to meet external supply requirements. The original feedwater line of a CFB boiler consists of a main-line regulating valve 11, a main-line economizer 12, a furnace water-cooled wall 71, a wall-wrapped superheater 72, a low-temperature superheater 13, a medium-temperature superheater 14, and a high-temperature superheater 15. The present invention utilizes the boiler water regulation mechanism of the CFB boiler to treat trace impurities in the water flowing through the furnace water-cooled wall 71 and the wall-wrapped superheater 72 in the steam extraction pipeline. This control also controls parameters such as the pH value, alkalinity, and dissolved solids content of the water in the steam extraction pipeline to prevent corrosion and scaling, thereby extending the service life of the steam extraction pipeline.

[0042] The embodiments of the present invention disclosed above are intended only to illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A boiler bypass system capable of extracting a large proportion of steam, characterized by: It includes a bypass flue gas pipeline and a steam extraction pipeline. The bypass flue gas pipeline is connected in parallel with the original boiler flue gas pipeline. The inlet of the steam extraction pipeline is connected to the original boiler water supply main line, and the outlet is connected to the external steam supply pipeline. The steam extraction pipeline is arranged around the bypass flue gas pipeline and flows through the original boiler area (7). The water quality is treated by the original boiler water quality treatment system; The bypass flue gas pipeline comprises a bypass inlet flue (1), a bypass flue (2) and a bypass outlet flue (3) which are connected in sequence. A bypass flue temperature regulating baffle (4) is provided at the connection between the bypass flue (2) and the bypass outlet flue (3) for regulating the flue gas flow rate. The bypass inlet flue (1) and the bypass outlet flue (3) are connected to the original boiler flue gas pipeline. A bypass economizer (6) and a bypass superheater (9) are provided in the bypass flue (2). The bypass economizer (6) is provided below the bypass superheater (9). The steam extraction pipeline comprises a bypass regulating valve (5), a bypass economizer (6), an original boiler area (7), a bypass superheater regulating valve (8) and a bypass superheater (9) which are connected in sequence. The heat relied upon by the steam extraction pipeline to generate steam comes from the bypass economizer (6) and the bypass superheater (9).

2. A boiler bypass system capable of extracting a large proportion of steam according to claim 1, characterized in that: The steam extraction pipeline further comprises a water spray desuperheater (10) which is arranged between the bypass superheater (9) and the outlet of the steam extraction pipeline.

3. A boiler bypass system capable of extracting a large proportion of steam according to claim 1, characterized in that: The bypass flue temperature regulating baffle (4) is made of stainless steel.

4. A boiler bypass system capable of extracting a large proportion of steam according to claim 3, characterized in that: The bypass economizer (6) is a stainless steel economizer.

5. A boiler bypass system capable of extracting a large proportion of steam according to claim 4, characterized in that: The bypass regulating valve (5) and the bypass superheater regulating valve (8) are both pneumatic regulating valves.

6. A boiler bypass system capable of extracting a large proportion of steam according to claim 5, characterized in that: The bypass superheater (9) is a convection superheater.

7. A boiler, characterized in that: A water treatment system is provided, and a bypass system for extracting steam in a large proportion from a boiler as described in any one of claims 1 to 6 is also provided, and the steam extraction pipeline flows through the active area of ​​the water treatment system.

8. The boiler according to claim 7, characterized in that: The boiler is a circulating fluidized bed boiler, the water quality treatment system acts on the furnace water-cooled wall (71) and the wall-wrapped superheater (72), and the steam extraction pipeline flows through the furnace water-cooled wall (71) and the wall-wrapped superheater (72) to perform water quality treatment.

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