Flue gas treatment system with functions of energy conservation, water conservation, flue gas purification and white smoke removal

Abstract

The utility model provides a flue gas treatment system with energy-saving, water-saving, flue gas purification and white smoke removal functions, which comprises a boiler, a denitration device, a rotary air preheater, a mixed air heater, a flue gas air heater, an electrostatic dust collector, a desulfurizing tower and a chimney which are connected in sequence, an air outlet of the flue gas air heater is connected with an air inlet of the rotary air preheater through a warm air pipeline, an air outlet of the rotary air preheater is connected with the boiler through a hot air pipeline, and an air outlet of the mixed air heater is connected with a flue between the desulfurizing tower and the chimney through a mixed air pipeline. According to the flue gas air heater, cold air can be heated, heated air is led into a boiler to be reused, energy saving is achieved, a steam air heater can be replaced, the problems of high energy consumption, poor reliability and the like are solved, the flue gas temperature can be reduced, a low-low-temperature coal economizer can be replaced, and the risk of water leakage of the low-low-temperature coal economizer is fundamentally eliminated.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal-fired boiler systems, and in particular relates to a flue gas treatment system with energy-saving and water-saving, flue gas purification and de-whitening functions. Background Art

[0002] When the boiler flue gas is discharged from the chimney, the gaseous water in the flue gas condenses into liquid water, causing the flue gas light transmittance to decrease, resulting in the phenomenon of white smoke coming out of the chimney. In order to meet environmental protection requirements, measures need to be taken to eliminate the white smoke plume from the chimney (i.e., flue gas de-whitening).

[0003] Conventional coal-fired boiler flue gas treatment systems not only waste a lot of heat sources and consume a lot of boiler coal, but also contain pollutants such as sulfur dioxide, carbon dioxide, and ash in the flue gas, which requires purification. A large amount of water is wasted as the flue gas is discharged into the atmosphere.

[0004] In the prior art, document CN112097287B discloses a boiler energy saving and flue gas desulfurization system, including a boiler, a denitrification device, a rotary air preheater, a mixed air heater, a flue gas heater, an electrostatic precipitator, a desulfurization tower and a chimney connected in sequence, using ambient air as the cold medium of the flue gas heater and the mixed air heater, and the warm air of 80-140°C obtained by heat exchange in the flue gas heater is used as the cold medium of the rotary air preheater, and the mixed hot air of more than 160°C obtained by heat exchange in the mixed air heater is introduced into the flue between the desulfurization tower and the chimney to heat the clean flue gas, and the flue gas is successively heated by the rotary air preheater, the mixed air heater, and the flue gas of 85-120°C obtained by heat exchange in the flue gas heater enters the electrostatic precipitator. However, the above scheme needs to be further optimized in terms of energy saving, water saving, flue gas purification and desulfurization functions.

[0005] In addition, research shows that dry burning to increase the wall temperature of the heat exchange tube can effectively alleviate the blockage of ammonium bisulfate in the flue, but as mentioned above, the existing coal-fired boiler flue gas system is not convenient for dry burning to effectively alleviate the secondary condensation and low-temperature corrosion of ammonium bisulfate. (This paragraph is mainly based on the description of authorization as much as possible) Utility Model Content

[0006] In view of the technical problems existing in the background technology, the purpose of the utility model is to provide a flue gas treatment system with energy and water saving, flue gas purification and de-whitening functions.

[0007] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme.

[0008] A flue gas treatment system with energy-saving and water-saving, flue gas purification and desulfurization functions, comprising a boiler, a denitrification device, a rotary air preheater, a flue gas heater, a dust collector, an induced draft fan, a desulfurization tower, an air condenser and a chimney connected in sequence, the air inlet of the flue gas heater is connected to the air condenser through a warm air duct, the condensate outlet of the air condenser is connected to a water treatment system, the air outlet of the flue gas heater is connected to the air inlet of the rotary air preheater through a medium-temperature air duct, and the air outlet of the rotary air preheater is connected to the boiler through a hot air duct; wherein a first air damper door is provided on the warm air duct, and a branch pipeline of the warm air duct is connected to the flue between the flue gas heater and the chimney.

[0009] In order to implement dry burning more smoothly and efficiently, the high-temperature flue gas bypass inlet is connected to the flue between the denitrification device and the rotary air preheater, the high-temperature flue gas bypass outlet is connected to the flue between the rotary air preheater and the flue gas heater, and a dry burning damper is provided on the high-temperature flue gas bypass.

[0010] Furthermore, a flue gas damper door is provided on the flue between the high-temperature flue gas bypass outlet and the rotary air preheater.

[0011] Furthermore, the heat exchange tubes of the flue gas heater and the air condenser are both three-dimensional fin heat exchange tubes.

[0012] Furthermore, a second air damper door is provided on the branch pipeline.

[0013] In order to better stabilize the flue gas and air pressures and make the flow field of the flue gas heater uniform, static pressure bellows are provided at the flue gas inlet and outlet and the air inlet and outlet of the flue gas heater.

[0014] As a preferred solution, the air condenser is arranged at the top of the desulfurization tower or on the clean flue gas duct at the outlet of the desulfurization tower, and the air condenser is arranged horizontally or vertically.

[0015] Furthermore, an air blower is provided on the air inlet side of the air condenser.

[0016] Beneficial effects: The utility model integrates energy-saving and water-saving, flue gas purification and desulfurization functions into a flue gas treatment system, which can achieve efficient flue gas purification, effectively remove pollutants such as sulfur dioxide, carbon dioxide, ash, etc. in the flue gas, save a large amount of water resources, fully recover the waste heat in the flue gas, achieve energy-saving and water-saving, and utilize surplus hot air to mix with the flue gas downstream of the desulfurization tower to achieve flue gas desulfurization. During operation, the temperature of flue gas entering the desulfurization tower can be lowered, the water consumption of the desulfurization process can be reduced, the moisture in the clean flue gas can be recovered through the air condenser, the heat exchange capacity of the air condenser is increased, the temperature of the clean flue gas is further reduced, deep water extraction, energy saving, cost reduction and efficiency improvement are achieved, and the surplus hot air (excluding boiler air) at the outlet of the air condenser is mixed with the clean flue gas at the outlet of the desulfurization tower to change the water vapor in the clean flue gas from a saturated state to an unsaturated state, and reduce the temperature difference between the mixed clean flue gas and the ambient temperature, thereby reducing the probability of water vapor condensing into water, better realizing flue gas desulfurization, and helping to reduce the risk of chimney corrosion; the utility model is adopted to facilitate dry burning to effectively alleviate the secondary condensation of ammonium bisulfate and low-temperature corrosion problems, a flue gas heater (tube side flue gas, no soot blower) is arranged below the flue gas side of the rotary air preheater to form a composite air preheater, and an air condenser is arranged at the outlet of the desulfurization tower, which can convert 8960890Nm 3 / h cold air is heated to 27℃ after heat exchange in the air condensation defogger, of which 1842140Nm 3 / h wind enters the flue gas heater and continues to heat up to 129℃ and enters the rotary preheater. At this time, the flue gas temperature at the outlet of the rotary preheater rises to about 190℃ and then enters the flue gas heater to cool down to 110℃ before entering the dust collector. The comprehensive temperature of the cold end outlet of the rotary air preheater is about 319℃, which effectively alleviates the problems of ammonium bisulfate blockage and low-temperature corrosion. The remaining 27℃ warm air discharged from the air condensation demister is mixed with the clean flue gas after condensation and demisting and is discharged through the chimney, which reduces the temperature and humidity of the clean flue gas discharged from the chimney and achieves deep de-whitening of the flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the flue gas treatment system in Example 1. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are only used to help understand the principle and core idea of ​​the present invention, and are not intended to limit the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, improvements made to the present invention also fall within the scope of protection of the claims of the present invention. Example

[0019] A flue gas treatment system with energy-saving and water-saving, flue gas purification and desulfurization functions, comprising a boiler 1, a denitrification device 2, a rotary air preheater 3, a flue gas heater 4, a dust collector 5, an induced draft fan 6, a desulfurization tower 7, an air condenser 8 and a chimney 9 connected in sequence, the air inlet of the flue gas heater 4 is connected to the air condenser 8 through a warm air duct 10, the condensate outlet of the air condenser 8 is connected to a water treatment system, the air outlet of the flue gas heater 4 is connected to the air inlet of the rotary air preheater 3 through a medium-temperature air duct 11, and the air outlet of the rotary air preheater 3 is connected to the boiler 1 through a hot air duct 12; wherein a first air damper door 19 is provided on the warm air duct 10, and a branch pipeline 13 of the warm air duct 10 is connected to the flue between the flue gas heater 4 and the chimney 9. wherein the heat exchange tubes of the flue gas heater 4 and the air condenser 8 are both three-dimensional fin heat exchange tubes.

[0020] In this embodiment, the inlet of the high-temperature flue gas bypass 14 is connected to the flue between the denitrification device 2 and the rotary air preheater 3, and the outlet of the high-temperature flue gas bypass 14 is connected to the flue between the rotary air preheater 3 and the flue gas heater 4. A dry-burning damper 15 is provided on the high-temperature flue gas bypass 14; a flue gas damper door 16 is provided on the flue between the outlet of the high-temperature flue gas bypass 14 and the rotary air preheater 3; a second air damper door 17 is provided on the branch pipeline 13; static pressure bellows are provided at the flue gas inlet and outlet and the air inlet and outlet of the flue gas heater 4; a blower 18 is provided on the air inlet side of the air condenser 8

[0021] In this embodiment, the air condenser 8 is arranged at the top of the desulfurization tower or on the clean flue gas duct at the outlet of the desulfurization tower, and the air condenser 8 is arranged horizontally or vertically.

[0022] In this embodiment, a composite air preheater consisting of a flue gas heater (pipe side flue gas, no soot blower) is vertically arranged below the flue gas side of the rotary air preheater, and an air condenser is arranged at the outlet of the desulfurization tower to transfer 8960890Nm 3 / h cold air is heated to 27℃ after heat exchange in air condenser, of which 1842140Nm 3 / h of wind enters the flue gas heater and continues to heat up to 129℃ before entering the rotary preheater. At this time, the flue gas temperature at the outlet of the rotary preheater rises to about 190℃ and then enters the flue gas heater to cool down to 110℃ before entering the dust collector. The comprehensive temperature of the cold end outlet of the rotary air preheater is about 319℃, which completely solves the problems of ammonium bisulfate blockage and low-temperature corrosion, and is convenient for dry burning and flexible regulation. The remaining 27℃ warm air discharged from the air condensation demister is mixed with the clean flue gas after condensation and demisting and is discharged through the chimney, which reduces the temperature and humidity of the clean flue gas discharged from the chimney and realizes flue gas de-whitening.

[0023] In this embodiment, the steam heater is omitted by adding an air condenser. The clean flue gas can be further purified by passing through the air condenser, and deep recovery of waste heat can be achieved while water is recovered. The entire system is simple, and surplus hot air is mixed with the clean flue gas at the outlet of the desulfurization tower to achieve chimney corrosion protection and flue gas desulfurization.

[0024] In this embodiment, the cold air is sent into the air condenser through the blower, and the air after absorbing heat is sent to the blower inlet on the boiler side, the cold air on the tube side and the clean flue gas on the shell side, and the heat exchanger adopts anodized aluminum alloy tubes and the outer surface of the tube is anti-corrosion treated;

[0025] The heat exchange tubes and tube sheets are non-welded, which facilitates maintenance and quick tube replacement, with low maintenance costs.

[0026] Taking a conventional coal-fired boiler flue gas treatment system as an example, after the scheme of this embodiment is adopted for transformation, it can be theoretically achieved that: all the flue gas waste heat recovered by air (flue gas preheating of the air preheater) is sent to the boiler, and the maximum energy saving is 1.082 (kJ / kg.℃) × 792 (kg / s) × (145-110) (℃) = 29993 kW, 7000 utilization hours are equivalent to standard coal = 29993 × 3600 / 29307 × 7000 = 25790 t / a, and according to the standard coal unit price of 240 yuan / ton, the coal cost can be saved by about = 25790 × 240 / 10000 = 6.19 million yuan, and the standard coal consumption for power generation can be reduced by = 17139 × 3600 / (660 × 1000) = 5.58g / kWh;

[0027] The benefit of eliminating the steam heater and increasing the air preheater inlet temperature is calculated based on the annual average temperature of 5℃ and the air preheater design inlet temperature of 50℃. The energy saving of eliminating the steam heater for the whole year = 1.005 (kJ / kg.℃) × 662 × (50-5) = 29939 kW, 7000 utilization hours is equivalent to standard coal = 7000×29939×3600 / 29307 / 1000=25743t / h. Calculated at the standard coal price of 240 yuan / ton, the coal cost can be saved by about = 25743×240 / 10000=6.18 million yuan; the original flue gas temperature drops from 145℃ to 110℃, which can reduce the water volume by about = (25790×3600)×7000 / 2376 / 1000=318108t / h, and the air condenser recovers 90t / h of condensed water. The annual water saving income is about = (318108+7000×90)×6.49 yuan / t=6.15 million yuan / a.

Claims

1. A flue gas treatment system with energy-saving and water-saving, flue gas purification and de-whitening functions, characterized in that: The system comprises a boiler (1), a denitration device (2), a rotary air preheater (3), a flue gas heater (4), a dust collector (5), an induced draft fan (6), a desulfurization tower (7), an air condenser (8) and a chimney (9) which are connected in sequence. The air inlet of the flue gas heater (4) is connected to the air condenser (8) via a warm air duct (10), the condensate outlet of the air condenser (8) is connected to a water treatment system, the air outlet of the flue gas heater (4) is connected to the air inlet of the rotary air preheater (3) via a medium-temperature air duct (11), and the air outlet of the rotary air preheater (3) is connected to the boiler (1) via a hot air duct (12); wherein a first air damper door (19) is provided on the hot air duct (10), and a branch pipe (13) of the hot air duct (10) is connected to the flue between the flue gas heater (4) and the chimney (9).

2. The flue gas treatment system according to claim 1, characterized in that: The inlet of the high-temperature flue gas bypass (14) is connected to the flue between the denitration device (2) and the rotary air preheater (3), and the outlet of the high-temperature flue gas bypass (14) is connected to the flue between the rotary air preheater (3) and the flue gas heater (4). A dry-burning damper (15) is provided on the high-temperature flue gas bypass (14).

3. The flue gas treatment system according to claim 2, characterized in that: A flue gas damper door (16) is provided on the flue between the outlet of the high-temperature flue gas bypass (14) and the rotary air preheater (3).

4. The flue gas treatment system according to any one of claims 1 to 3, characterized in that: The heat exchange tubes of the flue gas heater (4) and the air condenser (8) are both three-dimensional fin heat exchange tubes.

5. The flue gas treatment system according to claim 4, characterized in that: A second air damper door (17) is provided on the branch pipeline (13).

6. The flue gas treatment system according to claim 5, characterized in that: Static pressure bellows are provided at the flue gas inlet and outlet and the air inlet and outlet of the flue gas heater (4).

7. The flue gas treatment system according to claim 6, characterized in that: The air condenser (8) is arranged at the top of the desulfurization tower or on the clean flue gas duct at the outlet of the desulfurization tower. The air condenser (8) is arranged horizontally or vertically.

8. The flue gas treatment system according to claim 7, characterized in that: An air blower (18) is provided on the air inlet side of the air condenser (8).

Images