CN211232850U

CN211232850U - Boiler flue gas internal circulation system

Info

Publication number: CN211232850U
Application number: CN201920991709.0U
Authority: CN
Inventors: 方振明; 郑向阳; 朱水芳
Original assignee: Zhejiang Xianchuang Energy Technology Co ltd
Current assignee: Zhejiang Xianchuang Energy Technology Co ltd
Priority date: 2019-06-28
Filing date: 2019-06-28
Publication date: 2020-08-11
Anticipated expiration: 2029-06-28

Abstract

The utility model discloses a boiler flue gas internal circulation system, which comprises a boiler body, wherein the boiler body is formed by enclosing a front furnace wall, a rear furnace wall and a furnace side wall, the front furnace wall is provided with an air inlet, the air inlet is provided with a burner, the rear furnace wall is provided with a smoke outlet, a film wall is arranged in a furnace chamber of the boiler body along the furnace side wall, and the film wall, the front furnace wall, the rear furnace wall and the furnace side wall form a plurality of flue gas channels; still including setting up the flue gas circulation unit on flue gas passageway, the natural gas is fully burnt in the boiler body through the combustor, the high temperature flue gas that the burning produced loops through a plurality of flue gas passageways and erodees the heating diaphragm type wall and reach the exhaust port discharge boiler body of back oven wall, flue gas circulation unit guides the partial flue gas in the flue gas passageway in the furnace of boiler body to mix with fuel gas in the combustor, dilute fuel and combustion-supporting wind, it releases heat with concentrating to restrain the burning velocity of natural gas in furnace, thereby reduce combustion temperature, reduce the formation volume of oxynitride.

Description

Boiler flue gas internal circulation system

Technical Field

The utility model belongs to the technical field of the boiler, concretely relates to boiler flue gas internal circulation system.

Background

Natural gas is a well-known clean fuel, and in order to respond to the national call for energy conservation and emission reduction, natural gas is increasingly selected as a main fuel in boilers nowadays, but the combustion of the natural gas still generates a large amount of oxynitride, and the oxynitride can cause certain pollution to the environment.

The generation of nitrogen oxides is mainly related to the combustion temperature in the boiler, and the higher the combustion temperature of the mixed gas of natural gas and air in the boiler is, the more nitrogen oxides are generated, and nowadays, two methods are mainly adopted to reduce the combustion temperature: the method is characterized in that firstly, the method for recycling the flue gas in the furnace is a method for reducing the combustion temperature by utilizing high-speed airflow to entrain a part of burnt flue gas to mix with new combustion fuel and air, but the entrainment amount of the flue gas is related to the flow velocity of jet airflow, the flow velocity of the jet airflow is reduced, the entrainment amount is sharply reduced, the entrainment amount cannot be changed according to the requirement of low-nitrogen combustion, and the entrainment amount cannot be controlled; another method is a flue gas recirculation method outside the furnace, a recirculation induced draft fan is configured, a part (about 20%) of low-temperature flue gas is sucked at the smoke exhaust position of a boiler and mixed with main combustion air, so as to reduce the oxygen concentration and increase non-combustible media, thereby reducing the combustion temperature, but the increased 20% of non-combustible media are circulated in a long flow path between an air flue, a flue and other devices, the energy is inevitably consumed by the circulation flow, for example, a certain type of boiler (25 t/h), the flow resistance of the flue gas recirculation reaches 8000Pa, about 30kw of power is consumed, and finally the recirculation flue gas is mixed with the main combustion air, so as to dilute the oxygen concentration of the main combustion air, and the mixing pertinence is not strong, and the utilization rate is low.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a boiler flue gas inner circulating system, with the partial flue gas guide in the furnace to the combustor in with fuel gas mixture, dilute fuel and combustion-supporting wind, restrain the burning rate of natural gas in furnace and concentrate exothermic to reduce combustion temperature, reduce oxynitride's formation volume

In order to realize the technical purpose, the utility model discloses a following technical scheme: a boiler flue gas internal circulation system comprises a boiler body, wherein the boiler body is formed by enclosing a front furnace wall, a rear furnace wall and a furnace side wall, an air inlet is formed in the front furnace wall, a burner is arranged at the air inlet, a smoke outlet is formed in the rear furnace wall, a membrane type wall is arranged in a furnace chamber of the boiler body along the furnace side wall, and the membrane type wall, the front furnace wall, the rear furnace wall and the furnace side wall form a plurality of flue gas channels;

the combustor also comprises a flue gas circulating unit arranged on the flue gas channel, and the flue gas circulating unit guides part of flue gas in the flue gas channel to the combustor to be mixed with fuel gas.

Among the above-mentioned technical scheme, the natural gas is fully burnt in the boiler body through the combustor, the high temperature flue gas that the burning produced loops through a plurality of flue gas passageways and erodees heating diaphragm type wall and reach the exhaust port discharge boiler body of back oven wall, set up the flue gas circulation unit on the flue gas passageway, the flue gas circulation unit is with the furnace of boiler body in the partial flue gas guide of flue gas passageway mix with fuel gas in to the combustor, dilute fuel and combustion-supporting wind, it releases heat with concentrating to restrain the burning velocity of natural gas in furnace, thereby reduce the combustion temperature, reduce the formation volume of oxynitride.

Drawings

Fig. 1 is a schematic structural view of the present invention;

fig. 2 is a schematic view of the structure of the burner.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

A boiler flue gas internal circulation system comprises a boiler body 10, wherein the boiler body 10 is formed by enclosing a front furnace wall 11, a rear furnace wall 12 and a furnace side wall 13, an air inlet is formed in the front furnace wall 11, a combustor 20 is arranged at the air inlet, a smoke outlet is formed in the rear furnace wall 12, a membrane type wall 30 is arranged in a furnace chamber of the boiler body 10 along the furnace side wall 13, and the membrane type wall 30, the front furnace wall 11, the rear furnace wall 12 and the furnace side wall 13 form a plurality of flue gas channels;

and the flue gas circulating unit 40 is arranged on the flue gas channel, and the flue gas circulating unit 40 guides part of the flue gas in the flue gas channel to the combustor 20 to be mixed with the fuel gas.

Among the above-mentioned technical scheme, the natural gas fully burns in boiler body 10 through combustor 20, the high temperature flue gas that the burning produced loops through a plurality of flue gas passageways and erodes heating diaphragm type wall 30 and reach the exhaust port of back oven 12 and discharge boiler body 10, set up flue gas circulation unit 40 on the flue gas passageway, flue gas circulation unit 40 guides part flue gas among the flue gas passageway to combustor 20 in with boiler body 10's the furnace in with fuel gas mixture, dilute fuel and combustion-supporting wind, the burning velocity and the concentrated heat release of natural gas in the furnace are suppressed, thereby reduce combustion temperature, reduce the formation volume of oxynitride.

As shown in the figure, the flue gas channel comprises a first flue gas channel 50, a second flue gas channel 60 and a third flue gas channel 70, and is in a serpentine shape, and the first flue gas channel 50 is enclosed by a membrane wall I31, a forehearth wall 11 and a baffle plate 14 positioned in a hearth; the second flue gas channel 60 is formed by the film type wall I31 and the film type wall II 32 which are clamped; the third flue gas channel 70 is formed by the film wall II 32 and the furnace side wall 13. After being combusted, the fuel flows to the baffle plate 14 from the front furnace wall 11, namely flows in the first flue gas channel 50 and scours and heats the membrane wall I31, then enters the second flue gas channel 60 through a gap between the end part of the membrane wall I31 and the baffle plate 14, continues to scour and heat the membrane wall I31 and the membrane wall II 32 in the second flue gas channel 60, then enters the third flue gas channel 70 and scours and heats the other surface of the membrane wall II 32, and finally is discharged through a smoke outlet on the rear furnace wall 12.

In addition, the flue gas discharged from the smoke outlet on the furnace wall 12 is introduced into the waste heat boiler through a pipeline to heat the waste heat boiler, so that the heat in the flue gas generated by fuel combustion is further utilized, and the energy is saved.

The flue gas circulation unit 40 comprises a circulation fan 41, the transitional communication part of the second flue gas channel 60 and the third flue gas channel 70 is communicated with the air inlet of the circulation fan 41, and the air outlet of the circulation fan 41 is communicated with the air pipe in the combustor 20 through a circulation air pipeline 42. The transitional communication position of the second flue gas channel 60 and the third flue gas channel 70 is communicated with the air inlet of the circulating fan 41, at the moment, the circulating fan 41 extracts flue gas which is scoured and heated on the membrane wall 30, at the moment, the flue gas belongs to the flue gas with the medium temperature, after part of the flue gas is extracted by the circulating fan 41, the flue gas is communicated with the air pipe in the combustor 20 through a pipeline and is mixed and combusted with fuel in the air pipe, the fuel and combustion-supporting air are diluted, the combustion speed and the concentrated heat release of natural gas in the hearth are inhibited, the combustion temperature is reduced, and the generation amount of nitrogen oxides is reduced.

A first valve 421 is arranged on the circulating air pipeline 42, the first valve 421 is connected with a first servo motor 422, and the first servo motor 422 controls the flow of the circulating flue gas in the circulating air pipeline 42 through adjusting the first valve 421; in addition, a smoke detection unit is arranged at a smoke outlet of the back furnace wall (12), the smoke detection unit detects the components of the discharged smoke to obtain the content of oxynitride in the smoke, if the oxynitride is higher than a preset value, the smoke detection unit transmits a signal to the servo motor I422 and controls the flow of the circulating smoke in the circulating air pipeline 42 through the control regulating valve I421 to reduce the smoke amount in the smoke, so that the aim of effectively diluting fuel and combustion-supporting air is fulfilled.

The end face of the combustor 20 is in a circular shape consistent with an air inlet on the front furnace wall 11, in order to enable fuel to be combusted more fully, the combustor 20 comprises a gas inner spray gun 21, a gas outer spray gun 22, a circulating flue gas spray gun 23 and a mixing wind wheel 24, the gas inner spray gun 21 is located in the middle of the mixing wind wheel 24, the gas outer spray guns 22 are arranged at equal intervals along the circumferential direction of an outer ring of the mixing wind wheel 24, the circulating flue gas spray gun 23 is inserted between the gas outer spray guns 22, the combustor 20 is divided into a plurality of parts, and natural gas, combustion-supporting air and circulating flue gas mixed gas, and circulating flue gas and natural gas mixed gas are sequentially arranged from inside to outside, so.

The circulating air pipeline 42 is divided into two pipelines, a servo motor I422 is arranged on each pipeline, one pipeline of the circulating air pipeline 42 is connected with the air inlet end of the circulating flue gas spray gun 23, the other pipeline is communicated to the upstream of the mixing wind wheel 24,

the air preheating unit 80 is arranged on the smoke exhaust pipeline, one end of the air preheating unit 80 is connected with the air blower 81, and the other end of the air preheating unit 80 is connected to the upstream of the mixing wind wheel 24 through the air inlet pipe 25 so that air is mixed with the circulating smoke in the circulating wind pipeline 42.

The gas inlet pipe of the gas inner spray gun 21, the gas inlet pipe of the gas outer spray gun 22 and the air inlet pipe 25 are all provided with servo motors for controlling the gas flow.

Claims

1. The utility model provides a boiler flue gas inner circulating system, includes boiler body (10), its characterized in that: the boiler comprises a boiler body (10), a boiler body and a boiler body, wherein the boiler body is formed by enclosing a front boiler wall (11), a rear boiler wall (12) and a boiler side wall (13), an air inlet is formed in the front boiler wall (11), a combustor (20) is arranged at the air inlet, a smoke outlet is formed in the rear boiler wall (12), a membrane type wall (30) is arranged in a boiler chamber of the boiler body (10) along the boiler side wall (13), and the membrane type wall (30), the front boiler wall (11), the rear boiler wall (12) and the boiler side wall (13) form a plurality of smoke channels;

the device also comprises a flue gas circulating unit (40) arranged on the flue gas channel, wherein the flue gas circulating unit (40) guides part of flue gas in the flue gas channel to the combustor (20) to be mixed with fuel gas.

2. The boiler flue gas internal circulation system of claim 1, wherein: the smoke channel comprises a first smoke channel (50), a second smoke channel (60) and a third smoke channel (70), and is snakelike, and the first smoke channel (50) is formed by enclosing a membrane wall I (31), a front furnace wall (11) and a baffle plate (14) positioned in a furnace cavity; the second flue gas channel (60) is formed by clamping a membrane wall I (31) and a membrane wall II (32); the third flue gas channel (70) is formed by clamping a membrane wall II (32) and a furnace side wall (13).

3. The boiler flue gas internal circulation system of claim 2, wherein: the flue gas circulation unit (40) comprises a circulating fan (41), the transition communication position of the second flue gas channel (60) and the third flue gas channel (70) is communicated with the air inlet of the circulating fan (41), and the air outlet of the circulating fan (41) is communicated with an air pipe in the combustor (20) through a circulating air pipeline (42).

4. The boiler flue gas internal circulation system of claim 3, wherein: a first valve (421) is arranged on the circulating air pipeline (42), the first valve (421) is connected with a first servo motor (422), and the first servo motor (422) controls the flow of circulating flue gas in the circulating air pipeline (42) by adjusting the first valve (421);

a smoke detection unit is arranged at the smoke outlet of the back furnace wall (12).

5. The boiler flue gas internal circulation system of claim 2, wherein: the end face of the combustor (20) is circular and consistent with an air inlet on the front furnace wall (11), the combustor (20) comprises a gas inner spray gun (21), a gas outer spray gun (22), a circulating flue gas spray gun (23) and a mixing wind wheel (24), the gas inner spray gun (21) is located in the middle of the mixing wind wheel (24), the gas outer spray guns (22) are arranged along the circumferential direction of an outer ring of the mixing wind wheel (24) at equal intervals, and the circulating flue gas spray gun (23) is inserted between the gas outer spray guns (22).

6. The boiler flue gas internal circulation system of claim 4, wherein: the circulating air pipeline (42) is divided into two pipelines, a servo motor I (422) is arranged on each pipeline, one pipeline of the circulating air pipeline (42) is connected with the air inlet end of the circulating flue gas spray gun (23), and the other pipeline of the circulating air pipeline is communicated to the upstream of the mixing wind wheel (24).

7. The boiler flue gas internal circulation system of claim 5, wherein: the air preheating unit (80) is arranged on the smoke exhaust pipeline, one end of the air preheating unit (80) is connected with the air blower (81), and the other end of the air preheating unit is connected to the upstream of the mixing wind wheel (24) through an air inlet pipe (25) so that air is mixed with circulating smoke in the circulating wind pipeline (42).

8. The boiler flue gas internal circulation system of claim 5, wherein: and the air inlet pipe of the gas inner spray gun (21), the air inlet pipe of the gas outer spray gun (22) and the air inlet pipe (25) are respectively provided with a servo motor for controlling the gas flow.