Biomass circulating fluidized bed boiler adopting external air preheater

Abstract

The invention discloses a biomass circulating fluidized bed boiler adopting an external air preheater, and relates to a fluidized bed boiler. The problem that in an existing biomass fluidized bed boiler, due to the fact that a tubular air pre-heater structure is mostly adopted in a tail flue, a low-temperature section of an air pre-heater is generally seriously corroded and damaged is solved. The external air preheater is arranged outside the flue and does not make contact with smoke, boiler feed water is adopted for preheating air, the low-temperature corrosion and ash blocking conditions of a pipe bundle of the external air preheater are completely avoided, the smoke cooler is arranged in the third vertical flue at the tail of the boiler, and the smoke cooler is arranged in the third vertical flue at the tail of the boiler. And boiler feed water passing through the external air preheater enters the smoke cooler to cool boiler smoke, so that the condition of low-temperature corrosion of the boiler is avoided. The invention belongs to the technical field of biomass power generation and fluidized bed boilers.

Description

Technical Field

[0001] The invention relates to a fluidized bed boiler, in particular to a biomass circulating fluidized bed boiler adopting an external air preheater, and belongs to the technical field of biomass power generation and fluidized bed boilers. Background Art

[0002] Agricultural and forestry biomass fuels are rich in alkali metals such as potassium and sodium, and the chlorine content in the fuel is also high, all of which lead to serious corrosion problems on the heating surface of biomass boilers.

[0003] At present, most of the existing biomass fluidized bed boilers use a tubular air preheater structure in the tail flue. Although the air preheater low-temperature section tube bundle uses enameled tubes, after the unit has been running for a period of time, the air preheater tube bundle in the tail low-temperature section is still generally severely corroded and damaged. The damage of the preheater tube increases the boiler exhaust heat loss, reduces the boiler efficiency and unit reliability.

[0004] In summary, how to propose a new fluidized bed boiler to address the above technical issues has become an urgent problem to be solved by technicians in this field. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a biomass circulating fluidized bed boiler using an external air preheater.

[0006] The technical solution of the present invention is: a biomass circulating fluidized bed boiler using an external air preheater comprises a furnace, a cyclone separator, a first vertical flue, a second vertical flue, a third vertical flue, an external air preheater and a steam drum.

[0007] A water-cooled screen and a second-screen superheater are installed inside the furnace, and the working fluid inlet and outlet of the water-cooled screen are connected to the steam drum.

[0008] The smoke inlet and ash outlet of the cyclone separator are both connected to the furnace, and the smoke outlet of the cyclone separator is connected to the first vertical flue; the first vertical flue, the second vertical flue and the third vertical flue are connected in sequence.

[0009] The first vertical flue is equipped with a first screen superheater, the second vertical flue is equipped with a horizontal superheater and a high-temperature economizer, and the third vertical flue is equipped with a low-temperature economizer, a smoke cooler and an SCR denitrifier.

[0010] The external air preheater is installed on a steel frame platform or a foundation, and the working fluid inlet of the external air preheater is connected to the boiler feed water pipeline, and the working fluid outlet of the external air preheater is connected to the working fluid inlet of the smoke cooler.

[0011] The working fluid outlet of the smoke cooler is communicated with the working fluid inlet of the low-temperature economizer, and the working fluid outlet of the low-temperature economizer is communicated with the working fluid inlet of the high-temperature economizer.

[0012] The working medium outlet of the high temperature economizer is connected with the working medium inlet of the steam drum, and the working medium outlet of the steam drum is connected with the water-cooled wall of the furnace.

[0013] The working fluid inlet of the first screen superheater is connected to the working fluid outlet of the drum, and the working fluid outlet of the first screen superheater is connected to the working fluid inlet of the horizontal superheater.

[0014] The working fluid outlet of the horizontal superheater is communicated with the working fluid inlet of the second screen type superheater, and the working fluid outlet of the second screen type superheater is communicated with the steam turbine.

[0015] Compared with the prior art, the present invention has the following effects:

[0016] The external air preheater 7 of the present invention is arranged outside the flue and does not contact the flue gas. The boiler feed water is used to preheat the air, which completely avoids the low-temperature corrosion and ash blockage of the tube bundle of the external air preheater 7. The flue gas cooler 13 is arranged in the third vertical flue 6 at the rear of the boiler. The boiler feed water after passing through the external air preheater 7 enters the flue gas cooler 13 to cool the boiler flue gas, thereby avoiding the low-temperature corrosion of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the present invention;

[0018] Figure 2 It is a schematic diagram of the connection of the external air preheater 7, the low-temperature economizer 12 and the smoke cooler 13 of the present invention.

[0019] In the figure: 1. furnace; 2. cyclone separator; 3. return valve; 4. first vertical flue; 5. second vertical flue; 6. third vertical flue; 7. external air preheater; 8. water-cooled screen; 9. first screen superheater; 10. horizontal superheater; 11. high-temperature economizer; 12. low-temperature economizer; 13. smoke cooler; 14. regulating valve; 15. SCR denitrifier; 16. steam drum; 17. second screen superheater. DETAILED DESCRIPTION

[0020] In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0021] Specific implementation method 1: Combination Figure 1 and Figure 2To illustrate this embodiment, a biomass circulating fluidized bed boiler using an external air preheater in this embodiment includes a furnace 1, a cyclone separator 2, a first vertical flue 4, a second vertical flue 5, a third vertical flue 6, an external air preheater 7 and a steam drum 16.

[0022] A water-cooled panel 8 and a second panel superheater 17 are installed inside the furnace 1 . The working medium inlet and the working medium outlet of the water-cooled panel 8 are both connected to the steam drum 16 .

[0023] The flue gas inlet and ash outlet of the cyclone separator 2 are both connected to the furnace 1, and the flue gas outlet of the cyclone separator 2 is connected to the first vertical flue 4. Preferably, the cyclone separator 2 is an adiabatic cyclone separator, a water-cooled cyclone separator or a steam-cooled cyclone separator.

[0024] The first vertical flue 4, the second vertical flue 5 and the third vertical flue 6 are connected in sequence.

[0025] Furthermore, the first vertical flue 4 and the second vertical flue 5 are both covered by a water-cooled wall or a steam-cooled wall, and the third vertical flue 6 adopts a guard plate structure.

[0026] A first screen superheater 9 is installed inside the first vertical flue 4 , a horizontal superheater 10 and a high-temperature economizer 11 are installed inside the second vertical flue 5 , and a low-temperature economizer 12 , a smoke cooler 13 and an SCR denitrifier 15 are installed inside the third vertical flue 6 .

[0027] Furthermore, the pipe material of the low temperature section of the smoke cooler 13 is a smooth pipe, and the pipe material adopts a corrosion-resistant material such as ND steel to prevent the smoke cooler 13 from being blocked by ash and low-temperature corrosion.

[0028] The external air preheater 7 is installed on a steel frame platform or a foundation, and the working medium inlet of the external air preheater 7 is connected to the boiler feed water pipeline, and the working medium outlet of the external air preheater 7 is connected to the working medium inlet of the smoke cooler 13.

[0029] The working medium outlet of the smoke cooler 13 is communicated with the working medium inlet of the low-temperature economizer 12 , and the working medium outlet of the low-temperature economizer 12 is communicated with the working medium inlet of the high-temperature economizer 11 .

[0030] The working medium outlet of the high-temperature economizer 11 is communicated with the working medium inlet of the steam drum 16 , and the working medium outlet of the steam drum 16 is communicated with the water-cooled wall of the furnace 1 .

[0031] When the second vertical flue 5 adopts a water-cooled wall structure, the working fluid inlet of the first screen superheater 9 is connected to the working fluid outlet of the steam drum 16, and the working fluid outlet of the first screen superheater 9 is connected to the working fluid inlet of the horizontal superheater 10; when the second vertical flue 5 adopts a steam-cooled wall structure, the working fluid inlet of the steam-cooled wall is connected to the working fluid outlet of the steam drum 16, and the working fluid outlet of the steam-cooled wall is connected to the working fluid inlet of the first screen superheater 9, and the working fluid outlet of the first screen superheater 9 is connected to the working fluid inlet of the horizontal superheater 10.

[0032] The working medium outlet of the horizontal superheater 10 is communicated with the working medium inlet of the second screen-type superheater 17, and the working medium outlet of the second screen-type superheater 17 is communicated with the steam turbine.

[0033] In this embodiment, the ash outlet of the cyclone separator 2 is connected to the furnace 1 through the return valve 3.

[0034] In this embodiment, a regulating valve 14 is installed on the pipeline between the boiler feed water pipeline and the working medium inlet of the external air preheater 7 .

[0035] Furthermore, a regulating valve 14 is installed on the pipeline between the working medium inlet and the working medium outlet of the external air preheater 7 .

[0036] Furthermore, a regulating valve 14 is installed on the pipeline between the working medium inlet and the working medium outlet of the smoke cooler 13 .

[0037] Furthermore, a regulating valve 14 is installed on the pipeline between the working medium outlet of the smoke cooler 13 and the working medium inlet of the low-temperature economizer 12 .

[0038] Furthermore, a regulating valve 14 is installed on the pipeline between the boiler feed water pipeline and the working medium inlet of the low-temperature economizer 12 .

[0039] By installing regulating valves 14 on the above-mentioned pipelines, the flow rate of the working medium in each pipeline can be adjusted, thereby adjusting the boiler exhaust gas temperature and the hot air temperature.

[0040] Specific implementation method 2: Combination Figure 1 and Figure 2 To illustrate this embodiment, in this embodiment, the flue gas outlet of the cyclone separator 2 is connected to the top of the first vertical flue 4, and the bottom of the first vertical flue 4 is connected to the bottom of the second vertical flue 5; and in the second vertical flue 5, the high-temperature economizer 11 is arranged above the horizontal superheater 10.

[0041] Other components and connection relationships are the same as those in the first specific implementation method.

[0042] Specific implementation method three: Combination Figure 1 and Figure 2To explain this embodiment, in this embodiment, the top of the second vertical flue 5 is connected to the top of the third vertical flue 6, and in the third vertical flue 6, the SCR denitrifier 15 is arranged above the low-temperature economizer 12, and the low-temperature economizer 12 is arranged above the flue gas cooler 13. Other components and connection relationships are the same as those in the first or second embodiment.

[0043] How it works

[0044] The flue gas inlet and ash outlet of the cyclone separator 2 are both connected to the furnace 1, and the flue gas outlet of the cyclone separator 2 is connected to the first vertical flue 4. The first vertical flue 4, the second vertical flue 5 and the third vertical flue 6 are connected in sequence.

[0045] A first screen superheater 9 is installed inside the first vertical flue 4 , a horizontal superheater 10 and a high-temperature economizer 11 are installed inside the second vertical flue 5 , and a low-temperature economizer 12 , a smoke cooler 13 and an SCR denitrifier 15 are installed inside the third vertical flue 6 .

[0046] The external air preheater 7 is installed on a steel frame platform or foundation, and the working medium inlet of the external air preheater 7 is connected to the boiler feed water pipeline, and the working medium outlet of the external air preheater 7 is connected to the working medium inlet of the smoke cooler 13. With this arrangement, the external air preheater 7 does not contact the flue gas, and the boiler feed water first enters the external air preheater 7 to heat the boiler inlet air, which completely avoids low-temperature corrosion and ash blockage of the external air preheater 7.

[0047] The working medium outlet of the smoke cooler 13 is communicated with the working medium inlet of the low-temperature economizer 12 , and the working medium outlet of the low-temperature economizer 12 is communicated with the working medium inlet of the high-temperature economizer 11 .

[0048] The working medium outlet of the high-temperature economizer 11 is communicated with the working medium inlet of the steam drum 16 , and the working medium outlet of the steam drum 16 is communicated with the water-cooled wall of the furnace 1 .

[0049] The working medium inlet of the first screen superheater 9 is connected to the working medium outlet of the steam drum 16 , and the working medium outlet of the first screen superheater 9 is connected to the working medium inlet of the horizontal superheater 10 .

[0050] The working medium outlet of the horizontal superheater 10 is communicated with the working medium inlet of the second screen-type superheater 17, and the working medium outlet of the second screen-type superheater 17 is communicated with the steam turbine.

[0051] The present invention has been disclosed as above in the form of a preferred embodiment, but it is not intended to limit the present invention. Any simple modification, equivalent changes and modifications made to the above implementation cases by any professional and technical personnel who do not deviate from the content of the technical solution of the present invention and based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A biomass circulating fluidized bed boiler using an external air preheater, characterized in that: It comprises a furnace (1), a cyclone separator (2), a first vertical flue (4), a second vertical flue (5), a third vertical flue (6), an external air preheater (7) and a steam drum (16); A water-cooled screen (8) and a second screen-type superheater (17) are installed inside the furnace (1), and the working medium inlet and working medium outlet of the water-cooled screen (8) are both connected to the steam drum (16); The smoke inlet and ash outlet of the cyclone separator (2) are both connected to the furnace (1), and the smoke outlet of the cyclone separator (2) is connected to the first vertical flue (4); the first vertical flue (4), the second vertical flue (5) and the third vertical flue (6) are connected in sequence; A first screen superheater (9) is installed inside the first vertical flue (4), a horizontal superheater (10) and a high-temperature economizer (11) are installed inside the second vertical flue (5), and a low-temperature economizer (12), a smoke cooler (13) and an SCR denitrifier (15) are installed inside the third vertical flue (6); The external air preheater (7) is installed on a steel frame platform or a foundation, and the working medium inlet of the external air preheater (7) is connected to the boiler feed water pipeline, and the working medium outlet of the external air preheater (7) is connected to the working medium inlet of the smoke cooler (13); The working medium outlet of the smoke cooler (13) is connected to the working medium inlet of the low-temperature economizer (12), and the working medium outlet of the low-temperature economizer (12) is connected to the working medium inlet of the high-temperature economizer (11); The working medium outlet of the high-temperature economizer (11) is connected to the working medium inlet of the steam drum (16), and the working medium outlet of the steam drum (16) is connected to the water-cooled wall of the furnace (1); The working medium inlet of the first screen superheater (9) is connected to the working medium outlet of the steam drum (16), and the working medium outlet of the first screen superheater (9) is connected to the working medium inlet of the horizontal superheater (10); The working medium outlet of the horizontal superheater (10) is in communication with the working medium inlet of the second screen-type superheater (17), and the working medium outlet of the second screen-type superheater (17) is in communication with the steam turbine.

2. The biomass circulating fluidized bed boiler using an external air preheater according to claim 1, characterized in that: The flue gas outlet of the cyclone separator (2) is connected to the top of the first vertical flue (4), and the bottom of the first vertical flue (4) is connected to the bottom of the second vertical flue (5); and in the second vertical flue (5), the high-temperature economizer (11) is arranged above the horizontal superheater (10).

3. The biomass circulating fluidized bed boiler using an external air preheater according to claim 2, characterized in that: The top of the second vertical flue (5) is connected to the top of the third vertical flue (6), and in the third vertical flue (6), the SCR denitrifier (15) is arranged above the low-temperature economizer (12), and the low-temperature economizer (12) is arranged above the flue gas cooler (13).

4. The biomass circulating fluidized bed boiler using an external air preheater according to claim 1, characterized in that: The ash outlet of the cyclone separator (2) is connected to the furnace (1) via a return valve (3).

5. The biomass circulating fluidized bed boiler using an external air preheater according to claim 1, characterized in that: The cyclone separator (2) is an adiabatic cyclone separator, a water-cooled cyclone separator or a steam-cooled cyclone separator.

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