Biomass circulating fluidized bed boiler with external air preheater

Abstract

The application discloses a biomass circulating fluidized bed boiler with an external air preheater and relates to a fluidized bed boiler. In order to solve the problem that the low-temperature section of the air preheater is seriously corroded and damaged due to the fact that a tubular air preheater structure is mostly used in the tail flue of the existing biomass fluidized bed boiler, the external air preheater is arranged outside the flue and does not contact with the flue gas, the boiler feed water is used to preheat the air, the low-temperature corrosion and the ash blocking of the tube 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, the boiler feed water after the external air preheater is cooled in the smoke cooler to cool the flue gas of the boiler, and thus the low-temperature corrosion of the boiler is avoided. The application belongs to the technical field of biomass power generation and fluidized bed boiler.

Description

TECHNICAL FIELD

[0001] The present application 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 fields of biomass power generation and fluidized bed boiler. BACKGROUND

[0002] The agricultural and forestry biomass fuel is rich in alkali metals such as potassium and sodium, and the chlorine content in the fuel is also high, which leads to serious corrosion problems of the heating surface of the biomass boiler.

[0003] At present, the tail flue of the existing biomass fluidized bed boiler mostly adopts a tubular air preheater structure. Although the low-temperature section tube bundle of the air preheater adopts a plated enamel tube, after the unit runs for a period of time, the air preheater tube bundle of the tail low-temperature section is still generally seriously corroded and damaged. After the preheater pipe is damaged, the boiler exhaust heat loss is increased, the boiler efficiency is reduced, and the reliability of the unit is reduced.

[0004] In view of the above technical problems, how to propose a new fluidized bed boiler has become a problem to be solved by the technical personnel in the field. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a biomass circulating fluidized bed boiler adopting an external air preheater.

[0006] The technical scheme of the present application is: a biomass circulating fluidized bed boiler adopting an external air preheater, comprising 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-type superheater are installed inside the furnace, and the working medium inlet and outlet of the water-cooled screen are in communication with the steam drum.

[0008] The flue gas inlet and the ash outlet of the cyclone separator are in communication with the furnace, and the flue gas outlet of the cyclone separator is in communication with the first vertical flue; the first vertical flue, the second vertical flue and the third vertical flue are sequentially communicated.

[0009] A first screen-type superheater is installed inside the first vertical flue, a horizontal superheater and a high-temperature economizer are installed inside the second vertical flue, and a low-temperature economizer, a smoke cooler and an SCR denitrification device are installed inside the third vertical flue.

[0010] The external air preheater is installed on a steel platform or a foundation, and the working medium inlet of the external air preheater is in communication with the boiler feedwater pipeline, and the working medium outlet of the external air preheater is in communication with the working medium inlet of the smoke cooler.

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

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

[0013] The working medium inlet of the first screen-type superheater is communicated with the working medium outlet of the steam drum, and the working medium outlet of the first screen-type superheater is communicated with the working medium inlet of the horizontal-type superheater.

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

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

[0016] The external air preheater 7 is arranged outside the flue and does not contact with the flue gas, the boiler feed water preheated air is used, the low-temperature corrosion and the ash blocking of the tube bundle of the external air preheater 7 are completely avoided, the smoke cooler 13 is arranged in the third vertical flue 6 at the tail of the boiler, the boiler feed water after the external air preheater 7 enters the smoke cooler 13 to cool the boiler flue gas, and the low-temperature corrosion of the boiler is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic view of the present application;

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

[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-type superheater; 10, horizontal-type superheater; 11, high-temperature economizer; 12, low-temperature economizer; 13, smoke cooler; 14, regulating valve; 15, SCR denitration device; 16, steam drum; 17, second screen-type superheater. DETAILED DESCRIPTION

[0020] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application.

[0021] Specific embodiment one: in combination with Figure 1 and Figure 2The present embodiment is a biomass circulating fluidized bed boiler with an external air preheater, which comprises a furnace 1, a cyclone 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] The furnace 1 is internally provided with a water-cooled screen 8 and a second screen superheater 17, and the working medium inlet and outlet of the water-cooled screen 8 are in communication with the steam drum 16.

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

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

[0025] Further, the first vertical flue 4 and the second vertical flue 5 are each covered by a water-cooled wall or a steam-cooled wall, and the third vertical flue 6 adopts a shield structure.

[0026] The first vertical flue 4 is internally provided with a first screen superheater 9, the second vertical flue 5 is internally provided with a horizontal superheater 10 and a high-temperature economizer 11, and the third vertical flue 6 is internally provided with a low-temperature economizer 12, a smoke cooler 13, and an SCR denitrification device 15.

[0027] Further, the pipe material of the low-temperature section of the smoke cooler 13 is a light pipe, and the pipe material adopts a corrosion-resistant material such as ND steel, so as to avoid ash plugging and low-temperature corrosion of the smoke cooler 13.

[0028] The external air preheater 7 is installed on a steel platform or a foundation, and the working medium inlet of the external air preheater 7 is in communication with a boiler feedwater pipeline, and the working medium outlet of the external air preheater 7 is in communication with the working medium inlet of the smoke cooler 13.

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

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

[0031] When the second vertical flue 5 adopts the water-cooled wall structure, the working medium inlet of the first screen superheater 9 is communicated with the working medium outlet of the steam drum 16, and the working medium outlet of the first screen superheater 9 is communicated with the working medium inlet of the horizontal superheater 10; when the second vertical flue 5 adopts the steam-cooled wall structure, the working medium inlet of the steam-cooled wall is communicated with the working medium outlet of the steam drum 16, the working medium outlet of the steam-cooled wall is communicated with the working medium inlet of the first screen superheater 9, and the working medium outlet of the first screen superheater 9 is communicated with the working medium 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 superheater 17, and the working medium outlet of the second screen superheater 17 is communicated with the steam turbine.

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

[0034] In the embodiment, the 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] Further, the 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] Further, the regulating valve 14 is installed on the pipeline between the working medium inlet and the working medium outlet of the smoke cooler 13.

[0037] Further, the 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] Further, the 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 the regulating valve 14 on each pipeline, the working medium flow in each pipeline can be adjusted, so as to adjust the boiler flue gas temperature and the hot air temperature.

[0040] Specific implementation method two: combined with Figure 1 and Figure 2 In the embodiment, the flue gas outlet of the cyclone separator 2 is communicated with the top of the first vertical flue 4, the bottom of the first vertical flue 4 is communicated with the bottom of the second vertical flue 5, and the high-temperature economizer 11 is arranged above the horizontal superheater 10 in the second vertical flue 5.

[0041] The other components and connection relationships are the same as those in the specific implementation method one.

[0042] Specific implementation method three: combined with Figure 1 and Figure 2In the embodiment, the top of the second vertical flue 5 is communicated with the top of the third vertical flue 6, and in the third vertical flue 6, the SCR denitration device 15 is arranged above the low-temperature economizer 12, and the low-temperature economizer 12 is arranged above the smoke cooler 13. The other components and connection relationship are the same as those in the first or second embodiment.

[0043] Working principle

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

[0045] The first vertical flue 4 is internally provided with the first screen superheater 9, the second vertical flue 5 is internally provided with the horizontal superheater 10 and the high-temperature economizer 11, and the third vertical flue 6 is internally provided with the low-temperature economizer 12, the smoke cooler 13 and the SCR denitration device 15.

[0046] The external air preheater 7 is installed on a steel platform or a foundation, the working medium inlet of the external air preheater 7 is communicated with a boiler feed water pipeline, and the working medium outlet of the external air preheater 7 is communicated with the working medium inlet of the smoke cooler 13. In this way, the external air preheater 7 is not in contact with flue gas, the boiler feed water first enters the external air preheater 7 to heat the boiler inlet air, and the low-temperature corrosion and ash blocking of the external air preheater 7 are completely avoided.

[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 communicated with the working medium outlet of the steam drum 16, and the working medium outlet of the first screen superheater 9 is communicated with 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 superheater 17, and the working medium outlet of the second screen superheater 17 is communicated with a steam turbine.

[0051] The above-mentioned embodiments of the present application have been described, but the present application is not limited to the above-mentioned embodiments. Any modification, equivalent change and modification made to the above-mentioned embodiments according to the technical essence of the present application without departing from the technical solution of the present application also falls within the scope of the technical solution of the present application.

Claims

1. A biomass circulating fluidized bed boiler using an external air preheater, characterized by: 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 panel (8) and a second panel-type superheater (17) are installed inside the furnace (1), and the working medium inlet and the working medium outlet of the water-cooled panel (8) are both connected to the steam drum (16); 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; 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 flue gas 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 pipe, 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 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); 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 communicated with the working medium inlet of the second screen superheater (17), and the working medium outlet of the second screen superheater (17) is communicated 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), a 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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