Flue gas recirculation device for optimizing flue gas and primary air mixing mode

Abstract

The utility model provides a flue gas recirculation device for optimizing a flue gas and primary air mixing mode, and belongs to the field of flue gas recirculation devices for optimizing the flue gas and primary air mixing mode. The problem that according to the access mode of a flue gas recirculation pipeline, the outlet end of the flue gas recirculation pipeline is mostly connected with the inlet end of a primary air fan, low-temperature flue gas in the flue gas recirculation pipeline makes contact with primary air at the inlet end of the primary air fan to form acid liquor, and therefore corrosion of blades of the primary air fan is inevitably caused is solved. The boiler comprises a hearth, a flue, a chimney, a mixed air bellow, a separating and returning system, a primary air system, a backflow system and a flue gas recirculation system, the bottom of the hearth is connected with the mixed air bellow, the outlet end of the mixed air bellow is connected with the inlet end of a bed layer of the hearth, and the inlet end of the mixed air bellow is connected with the primary air system. And an induced draft fan is arranged on the induced draft pipeline. The device is mainly used for the fluidized bed boiler flue gas recirculation technology.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas recirculation of fluidized bed boilers, in particular to a flue gas recirculation device which optimizes the mixing mode of flue gas and primary air. Background Art

[0002] During the operation of coal-fired boilers, a certain amount of NO X As the country's nitrogen oxides (NO X ) Emission requirements are becoming increasingly stringent, increasing NO X The governance level has now become the research focus in the field of environmental protection. X The generation mechanism of NO is complex and is closely related to factors such as fuel characteristics, oxygen content, nitrogen content, temperature and furnace structure. X According to the different generation mechanisms, it can be divided into fuel type, thermal type and rapid type. Different types of boilers can apply different low-nitrogen combustion technologies or their combination to achieve NO X Emission reduction. As one of the low-nitrogen combustion technologies, flue gas recirculation technology has the advantages of easy transformation, suitability for a variety of furnace types, and stable combustion, and has considerable economic and social benefits. The working principle of the flue gas recirculation system is to extract a part of the low-temperature flue gas and mix it with the primary air, and reduce the primary air rate under the premise of ensuring the air volume required for normal fluidization, that is, to reduce the oxygen content in the initial stage of combustion, inhibit the bed temperature, and reduce NO X The flue gas recirculation duct is usually connected by connecting the outlet of the flue gas recirculation duct to the inlet of the primary fan. The low-temperature flue gas in the flue gas recirculation duct contacts the primary air at the inlet of the primary fan to form acid liquid, which inevitably causes corrosion of the primary fan blades. Utility Model Content

[0003] In view of this, the utility model aims to propose a flue gas recirculation device which optimizes the mixing mode of flue gas and primary air, so as to solve the problem that the access mode of the flue gas recirculation duct mostly adopts the method of connecting the outlet end of the flue gas recirculation duct to the inlet end of the primary fan, and the low-temperature flue gas in the flue gas recirculation duct contacts the primary air at the inlet end of the primary fan to form acid liquid, which inevitably causes corrosion of the primary fan blades.

[0004] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a flue gas recirculation device for optimizing the mixing mode of flue gas and primary air, which comprises a furnace, a flue, a chimney, a mixing wind box, a separation return system, a primary air system, a reflux system and a flue gas recirculation system, the bottom of the furnace is connected with a mixing wind box, the outlet end of the mixing wind box is connected with the inlet end of the bed layer of the furnace, the inlet end of the mixing wind box is connected with the primary air system, the outlet end of the furnace is connected with the inlet end of the flue through the separation return system, the outlet end of the flue is connected with the chimney through an induced draft duct, an induced draft fan is arranged on the induced draft duct, the inlet end of the flue gas recirculation system is connected with the induced draft duct between the induced draft fan and the chimney, the outlet end of the flue gas recirculation system is connected with the inlet end of the mixing wind box, and the reflux system is connected with the flue gas recirculation system.

[0005] Furthermore, the primary air system includes a primary air duct and a primary fan, the outlet end of the primary fan is connected to the inlet end of the mixing air box through the primary air duct, and the inlet end of the primary fan is connected to the outside air.

[0006] Furthermore, the separation and return system includes a separator, the outlet end of the furnace and the inlet end of the separator are connected by a pipeline, the gas outlet end of the separator is connected to the inlet end of the chimney through a pipeline, and the solid outlet end of the separator is connected to the solid inlet end of the furnace through a pipeline.

[0007] Furthermore, the flue gas recirculation system includes a flue gas recirculation pipeline and a flue gas recirculation fan, the flue gas recirculation fan is arranged on the flue gas recirculation pipeline, the inlet end of the flue gas recirculation pipeline is connected to the induced draft pipeline between the induced draft fan and the chimney, and the outlet end of the flue gas recirculation pipeline is connected to the inlet end of the mixing wind box.

[0008] Furthermore, the reflow system includes a reflow pipeline and an electric regulating valve, the inlet end of the reflow pipeline is connected to the flue gas recirculation pipeline at the outlet end of the flue gas recirculation fan, the outlet end of the reflow pipeline is connected to the flue gas recirculation pipeline at the inlet end of the flue gas recirculation fan, and the electric regulating valve is arranged on the reflow pipeline and close to the outlet end of the reflow pipeline.

[0009] Furthermore, a pressure transmitter and a differential pressure flowmeter are sequentially connected to the return pipeline near the outlet end of the return pipeline.

[0010] Furthermore, the flue gas recirculation pipelines on both sides of the inlet end of the reflux pipeline are respectively connected with a differential pressure flowmeter and a pressure transmitter.

[0011] Furthermore, a pneumatic gate valve is arranged on the flue gas recirculation pipeline near the outlet end of the flue gas recirculation pipeline.

[0012] Compared with the prior art, the beneficial effects of the utility model are:

[0013] 1. The utility model provides a flue gas recirculation device which optimizes the mixing mode of flue gas and primary air. A part of low-temperature flue gas is drawn out by a flue gas recirculation fan, and the drawn-out low-temperature flue gas is transported to a mixing bellows through a flue gas recirculation pipeline to be mixed with the primary air, thereby avoiding the occurrence of acid corrosion of the primary fan blades caused by the contact between the low-temperature flue gas and the primary air at the inlet end of the primary fan to form acid liquid, thereby extending the service life of the primary fan and reducing the repair and maintenance cost of the primary fan.

[0014] 2. The utility model provides a flue gas recirculation device which optimizes the mixing mode of flue gas and primary air. A return pipeline and an electric regulating valve are arranged on the flue gas recirculation pipeline to realize the regulation of the air volume, so that the nitrogen oxide emission under various load conditions meets the standard while ensuring the long-term stable operation of the whole device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:

[0016] Figure 1 The utility model is a schematic diagram of the overall structure of a flue gas recirculation device for optimizing the mixing mode of flue gas and primary air.

[0017] 1-furnace, 2-separator, 3-flue, 4-induced draft fan, 5-chimney, 6-electric regulating valve, 7-flue gas recirculation fan, 8-return pipeline, 9-flue gas recirculation pipeline, 10-primary fan, 11-mixing bellows, 12-pressure transmitter, 13-differential pressure flowmeter, 14-pneumatic gate valve. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely explain the technical solutions in the embodiments of the utility model. It should be noted that the embodiments and features in the embodiments of the utility model can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the utility model, not all of the embodiments.

[0019] See also Figure 1To illustrate the present embodiment, a flue gas recirculation device for optimizing the mixing mode of flue gas and primary air comprises a furnace 1, a flue 3, a chimney 5, a mixing wind box 11, a separation return system, a primary air system, a reflow system and a flue gas recirculation system, wherein the bottom of the furnace 1 is connected with a mixing wind box 11, the outlet end of the mixing wind box 11 is connected with the inlet end of the bed layer of the furnace 1, the inlet end of the mixing wind box 11 is connected with the primary air system, the outlet end of the furnace 1 is connected with the inlet end of the flue 3 through the separation return system, the outlet end of the flue 3 is connected with the chimney 5 through an induced draft duct, an induced draft fan 4 is arranged on the induced draft duct, the inlet end of the flue gas recirculation system is connected with the induced draft duct between the induced draft fan 4 and the chimney 5, the outlet end of the flue gas recirculation system is connected with the inlet end of the mixing wind box 11, and the reflow system is connected with the flue gas recirculation system.

[0020] The present embodiment utilizes the flue gas recirculation system to draw out a portion of the low-temperature flue gas in the induced draft duct, and conveys the drawn-out low-temperature flue gas to the mixing wind box 11 to be mixed with the primary air, thereby avoiding the occurrence of acid corrosion of the blades of the primary fan 10 caused by the contact of the low-temperature flue gas and the primary air at the inlet end of the primary fan 10 to form acid liquid, thereby extending the service life of the primary fan 10 and reducing the repair and maintenance cost of the primary fan 10.

[0021] The primary air system described in this embodiment includes a primary air duct and a primary fan 10, the outlet end of the primary fan 10 is connected to the inlet end of the mixing air box 11 through the primary air duct, and the inlet end of the primary fan 10 is connected to the outside air. The primary fan 10 is used to introduce the outside air as primary air into the mixing air box 11 through the primary air duct.

[0022] The separation and return system described in this embodiment includes a separator 2, the outlet end of the furnace 1 is connected to the inlet end of the separator 2 by a pipeline, the gas outlet end of the separator 2 is connected to the inlet end of the chimney 5 by a pipeline, and the solid outlet end of the separator 2 is connected to the solid inlet end of the furnace 1 by a pipeline. The separator 2 is used for gas-solid separation of the smoke generated in the furnace 1, and the smoke after separation and dust removal is transported from the gas outlet end of the separator 2 to the flue 3, and the separated solid dust and unburned solid fuel are transported back to the furnace 1 through the solid outlet end of the separator 2.

[0023] The flue gas recirculation system described in this embodiment includes a flue gas recirculation pipeline 9 and a flue gas recirculation fan 7. The flue gas recirculation fan 7 is arranged on the flue gas recirculation pipeline 9. The inlet end of the flue gas recirculation pipeline 9 is connected to the induced draft pipeline between the induced draft fan 4 and the chimney 5. The outlet end of the flue gas recirculation pipeline 9 is connected to the inlet end of the mixing wind box 11. The flue gas recirculation fan 7 is used to lead out a part of the low-temperature flue gas in the induced draft pipeline. The led-out low-temperature flue gas is transported to the mixing wind box 11 through the flue gas recirculation pipeline 9 to be mixed with the primary air.

[0024] The flue gas recirculation fan 7 described in this embodiment maintains a fixed frequency operation at a working condition 1000 Pa higher than that of the primary fan, thereby avoiding the jamming and return air backflow problems caused by the confrontation between the flue gas recirculation fan 7 and the induced draft fan 4.

[0025] The reflow system described in this embodiment includes a reflow pipeline 8 and an electric regulating valve 6. The inlet end of the reflow pipeline 8 is connected to the flue gas recirculation pipeline 9 at the outlet end of the flue gas recirculation fan 7, and the outlet end of the reflow pipeline 8 is connected to the flue gas recirculation pipeline 9 at the inlet end of the flue gas recirculation fan 7. The electric regulating valve 6 is arranged on the reflow pipeline 8 and close to the outlet end of the reflow pipeline 8. Part of the flue gas in the flue gas recirculation pipeline 9 is refluxed through the reflow pipeline 8, and the opening of the electric regulating valve 6 is used to control the flow of the reflux flue gas, and the control system is cooperated to achieve the purpose of controlling the flow. The reflow pipeline 8 and the electric regulating valve 6 are arranged on the flue gas recirculation pipeline 9 to realize the adjustment of the air volume, so that the nitrogen oxide emissions under various load conditions meet the standards while ensuring the long-term stable operation of the entire device.

[0026] In this embodiment, a pressure transmitter 12 and a differential pressure flowmeter 13 are connected in sequence to the return pipeline 8 near the outlet end of the return pipeline 8, and a differential pressure flowmeter 13 and a pressure transmitter 12 are connected to the flue gas recirculation pipeline 9 on both sides of the inlet end of the return pipeline 8, respectively. The pressure transmitter 12 is used to measure the flue gas pressure in the corresponding pipeline, and the differential pressure flowmeter 13 is used to measure the flue gas flow in the corresponding pipeline.

[0027] In this embodiment, a pneumatic gate valve 14 is provided on the flue gas recirculation pipeline 9 near the outlet end of the flue gas recirculation pipeline 9. The pneumatic gate valve 14 is used to control the connection between the flue gas recirculation pipeline 9 and the mixing wind box.

[0028] In this embodiment, a regulating valve is provided at the inlet end of the flue gas recirculation pipeline 9 to control the flow rate of the flue gas entering the flue gas recirculation pipeline 9 .

[0029] During operation, the flue gas generated in the furnace 1 is separated and dust-removed by the separator 2, and the low-temperature flue gas enters the flue 3, and then the low-temperature flue gas in the flue 3 is led out by the induced draft fan 4, and is led out to the chimney 5 through the induced draft pipeline and then discharged. Among them, a part of the low-temperature flue gas in the induced draft pipeline is introduced into the flue gas recirculation pipeline 9 under the action of the flue gas recirculation fan 7, and is transported to the mixing wind box 11 through the flue gas recirculation pipeline 9 to mix with the primary air and then sent to the bottom of the fluidized bed boiler bed layer, so as to ensure the air volume required for fluidization and reduce the primary air rate, that is, to reduce the oxygen content in the initial stage of combustion, suppress the bed temperature, and reduce NO X During this process, the flow rate of flue gas is controlled by utilizing the opening of the electric regulating valve 6, and the control system is used to achieve the purpose of controlling the flow rate, so that the nitrogen oxide emissions under various load conditions meet the standards while ensuring the long-term stable operation of the entire device.

[0030] The embodiments of the utility model disclosed above are only used to help explain the utility model. The embodiments do not describe all the details in detail, nor do they limit the utility model 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 utility model, so that technicians in the relevant technical field can well understand and use the utility model.

Claims

1. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air, characterized in that: It comprises a furnace (1), a flue (3), a chimney (5), a mixing wind box (11), a separation and return system, a primary air system, a reflow system and a flue gas recirculation system. The bottom of the furnace (1) is connected to a mixing wind box (11), the outlet end of the mixing wind box (11) is connected to the inlet end of the bed layer of the furnace (1), the inlet end of the mixing wind box (11) is connected to the primary air system, the outlet end of the furnace (1) is connected to the inlet end of the flue (3) through the separation and return system, the outlet end of the flue (3) is connected to the chimney (5) through an induced draft duct, an induced draft fan (4) is arranged on the induced draft duct, the inlet end of the flue gas recirculation system is connected to the induced draft duct between the induced draft fan (4) and the chimney (5), the outlet end of the flue gas recirculation system is connected to the inlet end of the mixing wind box (11), and the reflow system is connected to the flue gas recirculation system.

2. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 1, characterized in that: The primary air system comprises a primary air duct and a primary fan (10); the outlet end of the primary fan (10) is connected to the inlet end of a mixing air box (11) via the primary air duct, and the inlet end of the primary fan (10) is in communication with the outside air.

3. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 1, characterized in that: The separation and return system comprises a separator (2), the outlet end of the furnace (1) and the inlet end of the separator (2) are connected via a pipeline, the gas outlet end of the separator (2) is connected to the inlet end of the chimney (5) via a pipeline, and the solid outlet end of the separator (2) is connected to the solid inlet end of the furnace (1) via a pipeline.

4. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 1, characterized in that: The flue gas recirculation system comprises a flue gas recirculation pipeline (9) and a flue gas recirculation fan (7), wherein the flue gas recirculation fan (7) is arranged on the flue gas recirculation pipeline (9), the inlet end of the flue gas recirculation pipeline (9) is connected to the induced draft pipeline between the induced draft fan (4) and the chimney (5), and the outlet end of the flue gas recirculation pipeline (9) is connected to the inlet end of the mixing wind box (11).

5. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 4, characterized in that: The return system comprises a return pipeline (8) and an electric regulating valve (6); the inlet end of the return pipeline (8) is connected to the flue gas recirculation pipeline (9) at the outlet end of the flue gas recirculation fan (7); the outlet end of the return pipeline (8) is connected to the flue gas recirculation pipeline (9) at the inlet end of the flue gas recirculation fan (7); and the electric regulating valve (6) is arranged on the return pipeline (8) and close to the outlet end of the return pipeline (8).

6. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 5, characterized in that: A pressure transmitter (12) and a differential pressure flowmeter (13) are sequentially connected to the return line (8) near the outlet end of the return line (8).

7. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 6, characterized in that: The flue gas recirculation pipelines (9) on both sides of the inlet end of the return pipeline (8) are respectively connected to a differential pressure flow meter (13) and a pressure transmitter (12).

8. A flue gas recirculation device for optimizing the mixing mode of flue gas and primary air according to claim 7, characterized in that: A pneumatic gate valve (14) is provided on the flue gas recirculation pipeline (9) near the outlet end of the flue gas recirculation pipeline (9).

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