CN213395283U

CN213395283U - Flue gas recirculation system

Info

Publication number: CN213395283U
Application number: CN202022192244.8U
Authority: CN
Inventors: 张岭
Original assignee: Huaibei Shenneng Power Generation Co ltd
Current assignee: Huaibei Shenneng Power Generation Co ltd
Priority date: 2020-09-27
Filing date: 2020-09-27
Publication date: 2021-06-08
Anticipated expiration: 2030-09-27

Abstract

The utility model relates to a boiler technical field especially relates to a flue gas recirculation system. The flue gas recirculation system comprises a boiler, an air preheater, a first heat exchange device, a dust removal device and a recirculation fan which are sequentially communicated with an annular circulation loop; and a second heat exchange device is arranged on the annular circulation loop at the downstream of the dust removal device and at the upstream of the boiler. The hardness of the dust is reduced by the smoke cooled by the first heat exchange device, and the low-temperature working condition of the dust removal device can be met. The dust concentration of the flue gas passing through the dust removal device is reduced. The low-temperature and low-dust flue gas subjected to cooling and dust removal enters the recirculation fan, so that the abrasion of dust to the components of the recirculation fan is greatly reduced, and the availability of the recirculation fan is improved. The flue gas is heated up through the second heat exchange device and then enters the hearth of the boiler so as to ensure the heat efficiency of the boiler. The flue gas recirculation system can ensure the long-term safe and stable operation of the recirculation fan equipment and can also ensure that the boiler has higher thermal efficiency.

Description

Flue gas recirculation system

Technical Field

The utility model relates to a boiler technical field especially relates to a flue gas recirculation system.

Background

When the double reheating ultra-supercritical unit operates at low load, the condition that the temperature of the reheating steam is insufficient often exists, the smoke amount in a hearth can be increased by increasing a smoke recycling system, and therefore the temperature of the single reheating steam and the temperature of the double reheating steam can be improved. However, the low-temperature flue gas is recycled into the furnace chamber, which reduces the outlet flue gas temperature of the furnace chamber and increases the flue gas temperature, thereby reducing the efficiency of the boiler. However, the flue gas temperature is slightly high, which causes the problem of high dust hardness, and the flue gas dust concentration is relatively high, and the high-hardness and high-concentration dust can cause serious abrasion to the recirculation fan, thereby reducing the availability ratio of the fan. Conventional dust removal methods, such as electrostatic dust removal and cloth bag dust removal, are not suitable for high-temperature flue gas, but the temperature of the recirculated flue gas entering the furnace cannot be too low, otherwise, the efficiency of the boiler is reduced.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a flue gas recirculation system solves boiler recirculation fan's wearing and tearing problem, guarantees the thermal efficiency of boiler simultaneously.

To achieve the purpose, the utility model adopts the following technical proposal:

a flue gas recirculation system comprises a boiler, an air preheater, a first heat exchange device, a dust removal device and a recirculation fan which are sequentially communicated to form an annular circulation loop, wherein flue gas generated by the boiler flows out of the air preheater and then sequentially passes through the first heat exchange device, the dust removal device and the recirculation fan and then returns to the boiler;

and a second heat exchange device is arranged on the annular circulation loop and is positioned at the downstream of the dust removal device and at the upstream of the boiler, the first heat exchange device is used for cooling the flue gas, and the second heat exchange device is used for heating the flue gas.

Optionally, the second heat exchange means is disposed between the recirculation fan and the boiler.

Optionally, the second heat exchange device is arranged between the recirculation fan and the dust removal device.

Optionally, the first heat exchange device and the second heat exchange device exchange heat through a cold medium.

Optionally, the flue gas recirculation system further includes a first branch and a second branch, an inlet of the first branch is communicated with the first heat exchange device, an outlet of the first branch is communicated with the second heat exchange device, an outlet of the second branch is communicated with the first heat exchange device, an inlet of the second branch is communicated with the second heat exchange device, and the refrigerant medium circulates in the first branch and the second branch and exchanges heat with the flue gas.

Optionally, the heat exchange elements of the first heat exchange device and the second heat exchange device are heat pipes.

Optionally, the coolant medium is water, oil or ethanol.

Optionally, the dust removing device is an electric dust remover, a bag-type dust remover or an electric bag dust remover.

Optionally, a desulfurization device is further arranged between the dust removal device and the recirculation fan.

Optionally, the desulfurization unit is located upstream of the second heat exchange unit.

The utility model has the advantages that:

the utility model provides a flue gas recirculation system, including the boiler, the air preheater, the first heat transfer device, the dust collector and the recirculation fan that communicate in proper order and form annular circulation loop, the flue gas that the boiler produced returns the boiler after passing through first heat transfer device, dust collector and recirculation fan in proper order after flowing out from the air preheater; and second heat exchange devices are further arranged on the annular circulation loop at the downstream of the dust removal device and the upstream of the boiler, the first heat exchange device is used for cooling the flue gas, and the second heat exchange device is used for heating the flue gas. The hardness of the dust is reduced by the smoke cooled by the first heat exchange device, and the low-temperature working condition of the dust removal device can be met. The dust concentration of the flue gas passing through the dust removal device is reduced. The low-temperature and low-dust flue gas subjected to cooling and dust removal enters the recirculation fan, so that the abrasion of dust to the components of the recirculation fan is greatly reduced, and the availability of the recirculation fan is improved. The flue gas is heated up through the second heat exchange device and then enters the hearth of the boiler so as to ensure the heat efficiency of the boiler. The utility model provides a flue gas recirculation system can guarantee the long-term safety and stability operation of recirculation fan equipment, can guarantee again that the boiler has higher thermal efficiency.

Drawings

Fig. 1 is a schematic view of a flue gas recirculation system according to an embodiment of the present invention.

In the figure:

1. a boiler; 2. an air preheater; 3. a first heat exchange means; 4. a dust removal device; 5. a recirculation fan; 6. and the second heat exchange device.

Detailed Description

The technical solution of the present invention will be further explained with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the elements related to the present invention are shown in the drawings.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection or a removable connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

As shown in fig. 1, the present embodiment provides a flue gas recirculation system, which includes a boiler 1, an air preheater 2, a first heat exchange device 3, a dust removing device 4, a recirculation fan 5, and a second heat exchange device 6. The boiler 1, the air preheater 2, the first heat exchange device 3, the dust removal device 4 and the recirculation fan 5 are communicated end to end through a flue gas circulation pipeline to form an annular circulation loop. The flue gas that boiler 1 produced flows out from air preheater 2 and returns boiler 1 after first heat transfer device 3, dust collector 4 and recirculation fan 5 in proper order. The first heat exchange device 3 is used for cooling the flue gas entering the dust removal device 4. The hardness of the dust is reduced by the smoke cooled by the first heat exchange device 3, and the low-temperature working condition of the dust removal device 4 can be met.

The second heat exchange device 6 is positioned on the annular circulation loop at the downstream of the dust removal device 4 and at the upstream of the boiler 1 and is used for heating the flue gas coming out of the dust removal device 4. In this embodiment, the second heat exchange means 6 is arranged between the recirculation fan 5 and the boiler 1. Namely, the flue gas from the dust removing device 4 firstly passes through the recirculation fan 5, and the flue gas passing through the recirculation fan 5 enters the second heat exchange device 6 for temperature rise, and then enters the boiler 1. The dust concentration of the flue gas passing through the dust removal device 4 is reduced. The low-temperature and low-dust flue gas subjected to cooling and dust removal enters the recirculation fan 5, so that the abrasion of dust to parts of the recirculation fan 5 is greatly reduced, and the availability of the recirculation fan 5 is improved. And the flue gas from the recirculation fan 5 is heated by the second heat exchange device 6 and then enters the hearth, so that the boiler 1 can be ensured to have higher heat efficiency.

Optionally, in other embodiments, the second heat exchanging device 6 may also be disposed between the recirculation fan 5 and the dust removing device 4, that is, the flue gas enters the second heat exchanging device 6 for temperature rise after being subjected to dust removal by the dust removing device 4, and enters the boiler 1 after passing through the recirculation fan 5. The arrangement can also ensure the long-term safe and stable operation of the recirculation fan 5 and ensure the high thermal efficiency of the boiler.

Optionally, in this embodiment, the heat exchange elements of the first heat exchange device 3 and the second heat exchange device 6 are heat pipes, and the heat pipes can utilize the heat conduction principle and the rapid heat transfer property of the refrigerant medium to quickly transfer the heat of the heat generating object out of the heat source through the heat pipes, and the heat conduction capability of the heat pipes exceeds the heat conduction capability of any known metal. The heat pipe is adopted as the heat exchange device, which is beneficial to improving the efficiency of flue gas cooling and heating. Specifically, the heat pipe exchanges heat through a refrigerant medium, and the refrigerant medium is one of water, oil or ethanol.

Optionally, the flue gas recirculation system of this embodiment further includes a circulation heat exchange loop, and the circulation heat exchange loop includes first heat exchange device 3, second heat exchange device 6, first branch road and second branch road, and the import and the first heat exchange device 3 intercommunication of first branch road, export and second heat exchange device 6 intercommunication, the import and the second heat exchange device 6 intercommunication of second branch road, export and first heat exchange device 3 intercommunication. Specifically, the refrigerant medium absorbs heat from the first heat exchange device 3, the high-temperature refrigerant medium flows into the second heat exchange device 6 through the first branch, the refrigerant medium releases heat in the second heat exchange device 6, and the low-temperature refrigerant medium flows into the first heat exchange device 3 through the second branch and flows in a circulating manner. The circulating flow of the refrigerant medium absorbs heat in the first heat exchange device 3 and releases the heat to the flue gas in the second heat exchange device 6, so that the flue gas temperature loss can be reduced to a certain extent, namely, on the basis of protecting the recirculation fan 5 by cooling and dedusting, the flue gas temperature loss is reduced, the efficiency of the boiler 1 is ensured, and the effects of energy conservation and emission reduction are achieved.

Optionally, in this embodiment, the dust removing device 4 is a bag-type dust remover, and in other embodiments, an electric dust remover or an electric bag dust remover may also be used.

Optionally, a desulfurization device is further arranged between the dust removal device 4 and the recirculation fan 5, so that the corrosivity of the flue gas entering the recirculation fan 5 can be reduced, the recirculation fan 5 is protected, and the service life of the recirculation fan is prolonged.

It is obvious that the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A flue gas recirculation system is characterized by comprising a boiler (1), an air preheater (2), a first heat exchange device (3), a dust removal device (4) and a recirculation fan (5) which are sequentially communicated to form an annular circulation loop, wherein flue gas generated by the boiler (1) flows out of the air preheater (2) and then sequentially passes through the first heat exchange device (3), the dust removal device (4) and the recirculation fan (5) and then returns to the boiler (1);

and a second heat exchange device (6) is further arranged on the circulating loop and positioned at the downstream of the dust removal device (4) and at the upstream of the boiler (1), the first heat exchange device (3) is used for cooling the flue gas, and the second heat exchange device (6) is used for heating the flue gas.

2. A flue gas recirculation system according to claim 1, characterized in that the second heat exchange means (6) is arranged between the recirculation fan (5) and the boiler (1).

3. A flue gas recirculation system according to claim 1, characterized in that the second heat exchanging means (6) is arranged between the recirculation fan (5) and the dust removal device (4).

4. The flue gas recirculation system according to claim 1, wherein the first heat exchange device (3) and the second heat exchange device (6) exchange heat through a cold medium.

5. The flue gas recirculation system according to claim 4, further comprising a first branch and a second branch, wherein the inlet of the first branch is communicated with the first heat exchange device (3), the outlet of the first branch is communicated with the second heat exchange device (6), the outlet of the second branch is communicated with the first heat exchange device (3), the inlet of the second branch is communicated with the second heat exchange device (6), and the refrigerant medium circulates in the first branch and the second branch and exchanges heat with the flue gas.

6. The flue gas recirculation system of claim 1, wherein the heat exchange elements of the first heat exchange device (3) and the second heat exchange device (6) are heat pipes.

7. The flue gas recirculation system of claim 4, wherein the coolant medium is water, oil or ethanol.

8. The flue gas recirculation system according to claim 1, wherein the dust removal device (4) is an electric dust remover, a cloth bag dust remover or an electric bag dust remover.

9. A flue gas recirculation system according to claim 1, characterized in that a desulphurization device is further arranged between the dust removal device (4) and the recirculation fan (5).

10. A flue gas recirculation system according to claim 9, characterized in that the desulphurization device is located upstream of the second heat exchange device (6).