Bypass system capable of extracting steam in large proportion for boiler and boiler applying bypass system

Abstract

The invention provides a boiler bypass system capable of extracting steam in a large proportion and a boiler applying the system, and belongs to the technical field of boiler manufacturing and transformation. The problems that large influence is generated on boiler operation during steam extraction, a steam turbine needs to be transformed on a large scale during steam extraction of a built power plant, and the transformed steam turbine cannot well adapt to the working conditions of steam extraction and no steam extraction are solved. The system comprises a bypass flue gas pipeline and a steam extraction pipeline, the bypass flue gas pipeline is connected with an original boiler flue gas pipeline in parallel, an inlet of the steam extraction pipeline is communicated with an original boiler water supply main path, and an outlet of the steam extraction pipeline is communicated with an external steam supply pipeline and arranged around the bypass flue gas pipeline. And the water flows through the original boiler area and is treated by an original boiler water treatment system. The device is mainly used for decoupling a boiler steam extraction process and a boiler normal steam production process, and the influence on boiler operation during steam extraction is reduced.

Description

Technical Field

[0001] The 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, in order to improve the profitability of thermal power plants, superheated steam is often extracted from boilers to meet industrial production. Extracting reheated steam has a great impact on the steam turbine. Extracting superheated steam will reduce the amount of reheated steam, resulting in insufficient cooling capacity of the reheater, which brings safety hazards, especially the low load problem. The boiler cannot achieve a large-scale constant extraction, and the steam turbine needs to be extensively modified when the power plant is extracted. The modified steam turbine cannot adapt well to the working conditions of steam extraction and non-steam extraction at the same time. Summary of the invention

[0003] In view of this, in order to solve the problem that steam extraction has a great impact on boiler operation, and that the steam turbine of the built power plant needs to be extensively modified when extracting steam, and the modified steam turbine cannot adapt well to the working conditions of steam extraction and non-steam extraction. The present invention proposes a bypass system for a boiler that can extract steam in a large proportion and a boiler using the system, which increases the evaporation heating surface of the flue gas by opening a bypass flue, uses the economizer and superheater inside it to form a steam extraction pipeline, and produces steam for external demand, so as to realize the decoupling of the steam extraction process from the normal steam production process of the boiler, reduce the impact of steam extraction on the operation of the boiler, and can adapt to various working conditions with different external steam extraction requirements.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a bypass system for extracting steam from a boiler in a large proportion, comprising a bypass flue gas pipeline and a steam extraction pipeline, wherein 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 with the original boiler water supply main line, and the outlet is connected with the external steam supply pipeline, and the steam extraction pipeline is arranged around the bypass flue gas pipeline, and the water quality of the water flowing through the original boiler area is treated by the original boiler water quality treatment system;

[0005] The bypass flue gas pipeline comprises a bypass inlet flue, a bypass flue and a bypass outlet flue which 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 quality treatment system and a bypass system for extracting a large proportion of steam from the above boiler, wherein the steam extraction pipeline flows through the action area of ​​the water quality 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 to perform water quality treatment.

[0014] Compared with the prior art, the bypass system for extracting steam in a large proportion from a boiler and the boiler using the bypass 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, and the size of the heating surface of the original boiler remains unchanged. The economizer absorbs heat by utilizing the increased heat exchange area, and then cooperates with the superheater to produce steam for external demand extraction, thereby realizing the decoupling of the steam extraction process from the normal steam production process of the boiler, and reducing the impact of steam extraction on boiler operation.

[0016] 2. The present invention utilizes the water quality 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 pipeline 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 requirement for adjusting the quality of the extracted steam exceeds the regulating capacity of the flue damper, the water spray desuperheater is used to reduce the steam temperature, thereby further improving the regulating capacity and adaptability of the device.

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

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

[0021] Figure 1 It is a schematic diagram of the main structure of the bypass system of the present invention;

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

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

[0024] Figure 4 A schematic diagram of the main structure of a CFB boiler provided with a bypass system of the present invention;

[0025] Figure 5 It is the main structural diagram of CFB boiler;

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

[0027] Figure 7 It is a connection line 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 superheater. DETAILED DESCRIPTION

[0029] The following will be combined with the 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 in the embodiments can be combined with each other without conflict, and the described embodiments 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, wherein 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 with the original boiler water supply main pipeline, and the outlet is connected with the external steam supply pipeline, and the water quality of the steam extraction pipeline is treated by the original boiler water quality treatment system while being arranged around the bypass flue gas pipeline and flowing through the original boiler area 7;

[0031] The bypass flue gas pipeline includes 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 adjusting 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 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 of the boiler flue gas heating surface, the bypass flue gas pipeline serves 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 circuit, thereby achieving decoupling from the main heating surface. The newly added heating surface for steam extraction is arranged in an independent flue and connected in parallel with the main circuit of the boiler. The economizer is an evaporation heating surface, and the superheater is a superheating heating surface. The steam volume and flue gas volume 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 can increase the evaporation heating surface, and the heat absorption can be flexibly adjusted, reducing the amount of coal added for steam extraction, reducing the amount of flue gas added during steam extraction, and the heat absorption ratio of the economizer and superheater is the same as that of the boiler. It can be achieved that no matter whether the flue gas is added or reduced to the newly added flue, the heat absorption ratio of the evaporation and superheating heating surface of the boiler remains constant, and the main steam parameters of the boiler remain unchanged when the steam extraction amount changes, reducing the impact of the steam extraction process on the normal operation of the boiler. At the same time, with the help of the water quality treatment system of the original boiler, the water quality in the steam extraction pipeline is treated to prevent scale, corrosion and impurities from damaging the steam extraction pipeline, thereby extending the service life of the steam extraction pipeline, improving thermal efficiency and reducing operating costs. Although it flows through part of the original boiler, the steam heat generated by the steam extraction pipeline mainly comes from the bypass economizer 6 and the bypass superheater 9, so it will 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 in the present application also includes a water spray desuperheater 10, which is arranged between the bypass superheater 9 and the outlet of the steam extraction pipeline. The present invention also includes a water spray desuperheater 10, which has a simple structure and a small device volume, and is easy to install and maintain. When the external demand steam temperature decreases and the steam temperature generated by the steam extraction pipeline is too high, the water spray desuperheater 10 can quickly adjust the steam temperature to adapt to the load change and realize the precise adjustment of the steam temperature.

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

[0036] The bypass economizer 6 described in the present 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 regulating valve 5 and the bypass superheater regulating valve 8 described in the present application are both pneumatic regulating valves. The pneumatic regulating valve can quickly respond to changes in the control signal to ensure accurate control of the steam flow rate. The pneumatic regulating valve has good adaptability to environmental conditions such as temperature and humidity, can operate stably under a wide range of working conditions, and is particularly suitable for use in a boiler environment.

[0039] The bypass superheater 9 described in the present 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] A 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 above-mentioned boiler, wherein the steam extraction pipeline flows through the action area of ​​the water treatment system.

[0041] The boiler described in the present application is a CFB boiler, and 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 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 extracting steam. 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, and at the same time 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 feed water main circuit of the CFB boiler is the main circuit regulating valve 11, the main circuit economizer 12, the furnace water wall 71, the wall superheater 72, the low temperature superheater 13, the medium temperature superheater 14 and the high temperature superheater 15 connected in sequence. The present invention uses the boiler water regulating link of the CFB boiler to make the steam extraction pipeline flow through the furnace water wall 71 and the wall superheater 72 to treat the trace impurities in the water. The pH value, alkalinity and dissolved solid content of the water in the steam extraction pipeline are controlled to prevent corrosion and scaling, and extend the service life of the steam extraction pipeline.

[0042] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A boiler bypass system capable of extracting a large proportion of steam, characterized in that: It includes a bypass flue gas pipeline and a steam extraction pipeline, wherein 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 with the original boiler water supply main pipeline, and the outlet is connected with the external steam supply pipeline, and is arranged around the bypass flue gas pipeline, flows through the original boiler area (7), and uses the original boiler water quality treatment system to treat the water quality; 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 adjusting 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 arranged 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 on 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, wherein the steam extraction pipeline flows through the action area of ​​the water treatment system.

8. A 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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