CN108211655B

CN108211655B - Flue gas purification method for realizing zero discharge of wastewater

Info

Publication number: CN108211655B
Application number: CN201810134944.6A
Authority: CN
Inventors: 魏进超; 孙英; 李俊杰; 李勇
Original assignee: Zhongye Changtian International Engineering Co Ltd
Current assignee: Zhongye Changtian International Engineering Co Ltd
Priority date: 2018-02-09
Filing date: 2018-02-09
Publication date: 2020-05-12
Anticipated expiration: 2038-02-09
Also published as: CN108211655A

Abstract

The flue gas purification method for realizing zero discharge of waste water comprises the following steps of 1) enabling an original flue gas conveying pipeline to be divided into a bypass flue gas pipeline, 2) enabling flue gas to enter an adsorption tower through the original flue gas conveying pipeline and the bypass flue gas pipeline and be purified by activated carbon in the adsorption tower and then discharged, 3) transferring activated carbon to be regenerated from the bottom of the adsorption tower to an desorption tower for desorption and regeneration, transferring regenerated activated carbon from the bottom of the desorption tower to the adsorption tower, enabling desorption gas to enter a washing system to generate waste water, and 1) controlling the temperature of the flue gas, wherein the step comprises ① spraying the waste water generated by the washing system into the bypass flue gas pipeline, ② introducing cold air into the original flue gas conveying pipeline, ③ mixing the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline with the flue gas in the original flue gas conveying pipeline controlled by the cold air, enabling the mixed gas to enter the adsorption tower, and adjusting the temperature of the flue gas at the inlet of the adsorption tower to be within a specified range.

Description

Flue gas purification method for realizing zero discharge of wastewater

Technical Field

The invention relates to a flue gas purification technology adopting an activated carbon adsorption tower, in particular to a flue gas purification method for realizing zero discharge of waste water, belonging to the field of sintering flue gas treatment.

Background

For industrial flue gas, especially sintering machine flue gas in the steel industry, it is desirable to adopt a large-scale dry desulfurization and denitrification device and process comprising an activated carbon adsorption tower and an analysis tower. The activated carbon flue gas purification technology has the characteristics of simultaneous desulfurization and denitrification, realization of byproduct recycling, recyclable adsorbent, high desulfurization and denitrification efficiency and the like, and is a desulfurization and denitrification integrated technology with great development prospect. In a desulfurization and denitration apparatus including an activated carbon adsorption tower for adsorbing pollutants including sulfur oxides, nitrogen oxides, and dioxins from sintering flue gas or exhaust gas (particularly sintering flue gas of a sintering machine in the steel industry) and a desorption tower (or regeneration tower) for thermal regeneration of activated carbon.

However, the flue gas purification technology by the activated carbon method has high requirements on the control of the temperature of raw flue gas, the temperature of the raw flue gas after passing through a booster fan is often above 150 ℃ (for example, the temperature of flue gas at the inlet of an adsorption tower without being subjected to cooling treatment can reach 150-. In general, the normal temperature of the activated carbon bed layer in the activated carbon adsorption tower is 100-160 ℃, and is preferably controlled at 110-150 ℃.

In one aspect, the activated carbon bed temperature is strictly controlled to be below 165 deg.C, preferably below 160 deg.C, in order to prevent combustion of the activated carbon in the bed. This is because, although the ignition point of activated carbon is around 430 ℃, the chemical reaction occurring on the surface of activated carbon is generally an exothermic reaction, and the dust in flue gas contains a small amount of combustible, combustion-supporting substances, and the activated carbon itself also entrains combustible dust. If the temperature in the adsorption tower is not strictly controlled, the existence of the inflammable substances or inflammable dust can cause safety hazards at any time, the spontaneous combustion of the activated carbon in the adsorption tower with the height of dozens of meters can be caused if the temperature is light, and the dust explosion can be caused if the temperature is serious, and the two accidents are disastrous to a large-scale desulfurization and denitrification tower device. Therefore, for safety, the alarm temperature of the activated carbon bed is generally set to 165 ℃. The temperature of the sintering raw flue gas is generally 90-200 ℃ after being pressurized by a booster fan, preferably 100-180 ℃, the oxygen content in the sintering flue gas is high, and the temperature of a bed layer after the surface of active carbon in the tower is oxidized is 5-15 ℃ higher than that of inlet flue gas, so that the temperature of the flue gas entering the adsorption tower needs to be controlled in order to ensure the safe operation of the desulfurization and denitrification device, and the alarm temperature is generally set to 145 ℃. In addition, before the adsorption tower is stopped, the temperature of the activated carbon bed layer in the adsorption tower needs to be kept lower than 90 ℃, and at the moment, the activated carbon bed layer needs to be cooled, so that the temperature of the activated carbon bed layer also needs to be controlled in order to ensure safe stop.

On the other hand, when the activated carbon flue gas purification system is in normal operation, the temperature of the flue gas entering the adsorption tower needs to be strictly controlled to be higher than or not lower than 100 ℃, and preferably higher than or not lower than 110 ℃. This is because, if the flue gas temperature is lower than 100 ℃, the temperature of the water vapor contained in the sintering flue gas entering the bed is close to the dew point (or condensation point), and it is very easy to become water and react with sulfur oxides to become a strongly corrosive acid, resulting in severe corrosion of the apparatus and severely reducing the desulfurization and denitrification effects.

In the process of purifying the flue gas by adopting an activated carbon method, the raw flue gas is treated by the activated carbon in the adsorption tower and then is cleanly discharged, SO that SO is adsorbed₂The active carbon of the pollutants such as HCl, HF and the like is discharged from the adsorption tower and is conveyed to the desorption tower for high-temperature regeneration by a conveyor, and SO-rich substances are desorbed₂The mixed gas enters a washing system to remove impurities, and then the mixed gas is subjected to the next procedure to prepare a byproduct, SO that SO is realized₂The resource utilization is realized. The washing system will produce a small amount of waste water, this part of the waste water Cl^-、F^-High heavy metal content, but low pH value, and difficult treatment.

The traditional flue gas cooling method is to directly spray water mist into flue gas to realize flue gas cooling. This cooling method cannot use waste water (e.g., waste water generated from a washing system in an activated carbon method) as a water source because harmful elements in the waste water are cyclically concentrated in the system and corrode system equipment.

Disclosure of Invention

In view of the above-mentioned shortcomings in the prior art, the present invention aims to provide a flue gas purification method and system for realizing zero discharge of waste water. On the basis of the prior art, the invention adopts the original flue gas conveying pipeline to divide the bypass flue gas pipeline, and the waste water generated by the gas analyzed by the analyzing tower through the washing system is completely sprayed into the bypass flue gas pipeline to cool the bypass flue gas and remove dust from the waste water, thereby not only realizing the accurate control of the flue gas temperature, but also ensuring that the waste water generated by the washing system for flue gas purification can be completely and reasonably treated, and really realizing the zero discharge of the waste water.

According to a first embodiment of the invention, there is provided a flue gas purification process achieving zero emission of waste water:

a flue gas purification method for realizing zero discharge of waste water comprises the following steps:

1) a bypass flue gas pipeline is divided from a raw flue gas conveying pipeline for conveying high-temperature flue gas to the activated carbon adsorption tower, and the raw flue gas enters the adsorption tower through the raw flue gas conveying pipeline and the bypass flue gas pipeline;

2) the flue gas enters an activated carbon adsorption tower, is adsorbed and purified by activated carbon in the adsorption tower and then is discharged, and the activated carbon adsorbing pollutants in the flue gas is discharged from the bottom of the adsorption tower;

3) transferring the active carbon adsorbed with the pollutants into an absorption tower from the bottom of the absorption tower, allowing the active carbon adsorbed with the pollutants to be analyzed and regenerated, discharging the analyzed and regenerated active carbon from the bottom of the absorption tower, and transferring the active carbon into the absorption tower; the desorbed gas enters a washing system, and the washing system washes the desorbed gas and generates wastewater;

wherein: the step 1) also comprises a step of flue gas temperature control or a step of flue gas temperature regulation, and the step comprises the following substeps:

① temperature control of the flue gas in the bypass flue gas pipeline, wherein the bypass flue gas pipeline is provided with an atomizer, the waste water generated by the washing system is atomized by the atomizer and then mixed with the flue gas in the bypass flue gas pipeline, and the waste water exchanges heat with the flue gas entering the bypass flue gas pipeline to form a mixed gas of the flue gas and the waste water;

② controlling temperature of the flue gas in the original flue gas conveying pipeline by introducing cold air into the original flue gas conveying pipeline at the downstream of the bypass flue gas pipeline;

③ the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline is merged into the original flue gas conveying pipeline, and is mixed with the flue gas in the original flue gas conveying pipeline after the temperature control or the temperature adjustment by the cold air, and then the mixed gas enters the adsorption tower, and the temperature of the flue gas at the inlet of the adsorption tower is adjusted within the specified range.

In the sub-step ①, the mixed gas of the flue gas and the waste water means that when the waste water exchanges heat with the flue gas entering the bypass flue gas pipeline, the waste water is evaporated to become gaseous water, and the evaporated gaseous water is mixed with the flue gas, that is, the mixed gas of the flue gas and the waste water.

Preferably, in step 1) of the method, a first temperature measuring point is arranged upstream of the position of the raw flue gas conveying pipeline where the bypass flue gas pipeline is branched. And a second temperature measuring point is arranged between the position of the cold air introduced into the original flue gas conveying pipeline and the position of the bypass flue gas pipeline merged to the original flue gas conveying pipeline. And a third temperature measuring point is arranged on the bypass flue gas pipeline and is positioned at the downstream of the dust remover. And a fourth temperature measuring point is arranged on the original flue gas conveying pipeline and at the downstream of the position where the bypass flue gas pipeline is combined to the original flue gas conveying pipeline. The first temperature measuring point detects the flue gas temperature T1 in the flue at the corresponding position on line. The second temperature measuring point detects the flue gas temperature T2 in the flue at the corresponding position on line. And the third temperature measuring point detects the flue gas temperature T3 in the flue at the corresponding position on line. And the fourth temperature measuring point detects the flue gas temperature T4 in the flue at the corresponding position on line. Wherein the target or set temperature value at the fourth temperature measurement point is T4_{Is provided with}。

According to the heat Q released by the flue gas entering the bypass flue gas pipeline_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct_{Water (W)}And equalising, calculating and adjusting the amount of flue gas entering the bypass flue gas duct in sub-step ① further dependent on the heat Q released by the flue gas entering the adsorption tower through the raw flue gas duct_{Cigarette 2}The heat Q absorbed by cold air introduced into the raw flue gas conveying pipeline_{Qi (Qi)}And (3) equally calculating and adjusting the amount of cold air introduced into the raw flue gas duct in the substep ② the temperature T4 at the fourth temperature measurement point is adjusted or controlled to be T4 by adjusting the amount of flue gas entering the bypass flue gas duct and the amount of cold air introduced into the raw flue gas duct_{Is provided with}A temperature range of + -t deg.C, wherein t deg.C is in the range of 1-5 deg.C.

Preferably, the target or set value of the temperature at the fourth temperature measuring point T4_{Is provided with}The temperature is 100-145 ℃, preferably 110-140 ℃; i.e. the temperature of the flue gas at the inlet of the adsorption column is adjusted within a specified range, for example within the range of 100 ℃ and 145 ℃, preferably within the range of 110 ℃ and 140 ℃.

Preferably, step 1) of the method further includes detecting the content of sulfur oxides in the raw flue gas, and calculating the amount of wastewater generated by the scrubbing system according to the content of sulfur oxides in the raw flue gas, specifically:

the total amount of the smoke measured by the flowmeter at the upstream of the first temperature measuring point is M₀Detecting SO in the original flue gas₂In a concentration of

Whereby the amount of wastewater M produced by the washing system_{Water (W)}Comprises the following steps:

wherein the amount M of waste water produced by the washing system_{Water (W)}The unit t/h; total amount of flue gas M₀Unit Nm³H; detected SO in raw flue gas₂Concentration of

Unit mg/Nm³；k₁Is a constant, and has a value of 0.9 to 1.6.

Preferably, in step 3) of the above method, the wastewater generated by the washing system is stored in a wastewater tank. The waste water enters the atomizer from the waste water storage tank along the waste water input pipeline. Preferably, the wastewater in the wastewater storage tank is neutral or alkaline. Preferably, a waste water pump is arranged on the waste water input pipeline and provides power for the waste water to enter the atomizer.

Preferably, in sub-step ② of the method, the cool air is delivered from an air duct to a raw flue gas delivery duct.

Preferably, said heat Q released according to the flue gas entering the bypass flue gas duct is_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct_{Water (W)}And (3) equally, calculating and adjusting the amount of the flue gas entering the bypass flue gas pipeline in the substep ①, specifically:

the first temperature measuring point detects the original flue gas temperature as T1, and the temperature of the mixed gas of the flue gas and the waste water at the third temperature measuring point is set as T3_{Is provided with}Wherein: t3_{Is provided with}At a temperature of 100-Taking values in a temperature range;

a) calculating the heat required by wastewater treatment: the amount of wastewater produced by the washing system is M_{Water (W)}Detecting the initial temperature of the wastewater as T_{Water (W)}Whereby the heat Q to be absorbed is required for treating the waste water produced by the washing system_{Water (W)}Comprises the following steps:

Q_{water (W)}＝M_{Water (W)}r_{Water (W)}+C_{Water vapour}M_{Water (W)}ΔT_{Water (W)}＝M_{Water (W)}(r_{Water (W)}+C_{Water vapour}(T3_{Is provided with}-T_{Water (W)})) (1)，

In the formula (1), r_{Water (W)}Is the heat of vaporization of the waste water, C_{Water vapour}The specific heat capacity of water vapor;

b) calculating the required flue gas amount of a bypass flue gas pipeline: setting the amount of the flue gas entering the bypass flue gas pipeline as M₁Whereby the heat Q released by the flue gas entering the bypass flue gas duct_{Cigarette 1}Comprises the following steps:

Q_{cigarette 1}＝C_{Cigarette with heating means}M₁ΔT_{Cigarette 1}＝C_{Cigarette with heating means}M₁(T1-T3_{Is provided with}) (2)，

C in formula (2)_{Cigarette with heating means}The specific heat capacity of the flue gas;

heat Q released by flue gas entering the bypass flue gas duct_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct_{Water (W)}Equality, we can get:

C_{cigarette with heating means}M₁(T1-T3_{Is provided with})＝M_{Water (W)}(r_{Water (W)}+C_{Water vapour}(T3_{Is provided with}-T_{Water (W)})) (3)，

Obtaining the following components:

M₁＝M_{water (W)}(r_{Water (W)}+C_{Water vapour}(T3_{Is provided with}-T_{Water (W)}))/(C_{Cigarette with heating means}(T1-T3_{Is provided with})) (4)；

Adjusting the opening degree of a bypass valve on the bypass flue gas pipeline to ensure that the amount of the flue gas entering the bypass flue gas pipeline is M₁。

In the invention, the temperature T3 of the mixed gas of the flue gas and the waste water after the heat exchange of the flue gas and the waste water is generally set according to specific conditions_{Is provided with}. For example, considerTo try to minimise the load and wear on the atomiser and precipitator upstream of the third temperature measurement point, a T3 is typically set_{Is provided with}Is T4_{Is provided with}Of (e.g. T3)_{Is provided with}＝105℃。

In addition, the waste water exchanges heat with the flue gas, the waste water evaporates to absorb heat, the heat absorbed by the water evaporation is generally calculated by dividing into two parts, one part is the initial temperature T_{Water (W)}Is evaporated to a temperature T_{Water (W)}Water vapor of (2) having a heat absorption of M_{Water (W)}r_{Water (W)}The other part is at a temperature T_{Water (W)}Is heated to a temperature of T3_{Is provided with}Water vapor of (2), heat absorption capacity is C_{Water vapour}M_{Water (W)}ΔT_{Water (W)}。

Preferably, the heat Q released by the flue gas entering the adsorption tower through the raw flue gas conveying pipeline is further determined_{Cigarette 2}The heat Q absorbed by cold air introduced into the raw flue gas conveying pipeline_{Qi (Qi)}And (3) equality, calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline in the substep ②, specifically:

the total amount of the smoke measured by the flowmeter at the upstream of the first temperature measuring point is M₀The temperature of the original smoke detected by the first temperature measuring point is T1, and the temperature of the mixed gas of the smoke and the cold air at the position of the second temperature measuring point is set to be T2_{Is provided with}Wherein: t2_{Is provided with}The temperature is 100-160 ℃, and the value is preferably within the range of 110-140 ℃;

a) calculating the heat quantity to be released by the original flue gas in the original flue gas conveying pipeline: the amount of flue gas entering the adsorption tower through the raw flue gas conveying pipeline is (M)₀-M₁) The heat Q released by the flue gas entering the adsorption tower through the raw flue gas conveying pipeline_{Cigarette 2}Comprises the following steps:

Q_{cigarette 2}＝C_{Cigarette with heating means}(M₀-M₁)ΔT_{Cigarette 2}＝C_{Cigarette with heating means}(M₀-M₁)(T1-T2_{Is provided with}) (5)，

b) Calculating the amount of cold air introduced into the original flue gas conveying pipeline: the quantity of cold air introduced into the original flue gas conveying pipeline is set to be M_{Qi (Qi)}Measuring the initial temperature of the cold air as T_{Qi (Qi)}Whereby the cold air passing into the raw flue gas duct absorbs heatQ_{Qi (Qi)}Comprises the following steps:

Q_{qi (Qi)}＝C_{Qi (Qi)}M_{Qi (Qi)}ΔT_{Qi (Qi)}＝C_{Qi (Qi)}M_{Qi (Qi)}(T2_{Is provided with}-T_{Qi (Qi)}) (6)，

C in formula (6)_{Qi (Qi)}Is the specific heat capacity of the cold air;

heat Q released by flue gas entering the adsorption column through the raw flue gas duct_{Cigarette 2}The heat Q absorbed by cold air introduced into the raw flue gas conveying pipeline_{Qi (Qi)}Equality, we can get:

C_{cigarette with heating means}(M₀-M₁)(T1-T2_{Is provided with})＝C_{Qi (Qi)}M_{Qi (Qi)}(T2_{Is provided with}-T_{Qi (Qi)}) (7)；

Obtaining the following components:

M_{qi (Qi)}＝C_{Cigarette with heating means}(M₀-M₁)(T1-T2_{Is provided with})/(C_{Qi (Qi)}(T2_{Is provided with}-T_{Qi (Qi)})) (8)；

The opening degree of a cold air valve on the air pipeline is adjusted, so that the amount of cold air introduced into the original flue gas conveying pipeline is M_{Qi (Qi)}。

Preferably, the temperature T4 of the fourth temperature measuring point is adjusted or controlled at T4 by adjusting the amount of flue gas entering the bypass flue gas duct and the amount of cold air introduced into the raw flue gas conveying duct_{Is provided with}The range of +/-t ℃ is as follows:

the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline is mixed with the mixed gas of the flue gas and the cold air in the original flue gas conveying pipeline after the temperature of the flue gas and the waste water is controlled or regulated by the cold air, after the two paths of gas are subjected to heat exchange, the temperature T4 of a fourth temperature measuring point is regulated or controlled at T4_{Is provided with}The range of +/-t ℃. The heat Q absorbed (or released) by the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline_{Smoke and water}The heat Q released (or absorbed) by the mixed gas of the flue gas and the cold air in the raw flue gas conveying pipeline_{Smoke and gas}Equal, i.e.:

Q_{smoke and water}＝Q_{Smoke and gas}(9)，

Namely: c₁(M₁+M_{Water (W)})(T4_{Is provided with}-T3_{Is provided with})＝C₂(M₀-M₁+M_{Qi (Qi)})(T2_{Is provided with}-T4_{Is provided with}) (10)，

C in formula (10)₁The specific heat capacity of the mixed gas of the flue gas and the waste water; c₂Is the specific heat capacity of the mixed gas of the flue gas and the cold air.

Preferably, T2_{Is provided with}＝T3_{Is provided with}＝T4_{Is provided with}。

In the invention, in order to make the flue gas temperature after the two flue gases in the bypass flue gas pipeline and the original flue gas conveying pipeline are mixed (i.e. the flue gas temperature T4 in the flue at the position corresponding to the fourth temperature measuring point) be controlled at T4 more easily_{Is provided with}The temperature of the flue gas before the two paths of flue gas are mixed is set or controlled to be T4 within the range of +/-T DEG C_{Is provided with}I.e. T3_{Is provided with}＝T4_{Is provided with}，T2_{Is provided with}＝T4_{Is provided with}。

Preferably, the flue gas temperature T2 in the flue at the corresponding position is detected on line according to the second temperature measuring point. If T2 equals T2_{Is provided with}Continuing to operate; t2 not equal to T2_{Is provided with}Adjusting the amount of cold air introduced into the original flue gas conveying pipe so that T2 is equal to T2_{Is provided with}。

T2 is greater than T2_{Is provided with}During the process, the opening degree of a cold air valve on the air pipeline is adjusted to increase the amount of cold air introduced into the original flue gas conveying pipeline, so that T2 is equal to T2_{Is provided with}(ii) a T2 less than T2_{Is provided with}During the process, the opening degree of a cold air valve on the air pipeline is reduced, so that the amount of cold air introduced into the original flue gas conveying pipeline is reduced, and T2 is equal to T2_{Is provided with}。

And detecting the flue gas temperature T3 in the flue at the corresponding position on line according to the third temperature measuring point. If T3 equals T3_{Is provided with}Continuing to operate; t3 not equal to T3_{Is provided with}Adjusting the amount of flue gas entering the bypass flue gas duct such that T3 equals T3_{Is provided with}。

T3 is greater than T3_{Is provided with}At this time, the opening of the bypass valve on the bypass flue gas duct is reduced to reduce the amount of flue gas entering the bypass flue gas duct so that T3 is equal to T3_{Is provided with}(ii) a T3 less than T3_{Is provided with}When the opening degree of the bypass valve on the bypass flue gas pipeline is increased, the amount of the flue gas entering the bypass flue gas pipeline is increased, and T3 and the like are enabled to beAt T3_{Is provided with}。

And detecting the flue gas temperature T4 in the flue at the corresponding position on line according to the fourth temperature measuring point. If T4 equals T4_{Is provided with}Continuing to operate; t4 not equal to T4_{Is provided with}Adjusting the amount of cold air introduced into the original flue gas duct and the amount of flue gas entering the bypass flue gas duct so that T4 equals T4_{Is provided with}。

T4 is greater than T4_{Is provided with}During the process, the opening degree of a cold air valve on the air pipeline is adjusted to increase the amount of cold air introduced into the original flue gas conveying pipeline, and the opening degree of a bypass valve on the bypass flue gas pipeline is adjusted to decrease the amount of flue gas entering the bypass flue gas pipeline, so that T4 is equal to T4_{Is provided with}(ii) a T4 less than T4_{Is provided with}During the process, the opening degree of a cold air valve on the air pipeline is reduced, so that the amount of cold air introduced into the original flue gas conveying pipeline is reduced, meanwhile, the opening degree of a bypass valve on the bypass flue gas pipeline is increased, so that the amount of flue gas entering the bypass flue gas pipeline is increased, and T4 is equal to T4_{Is provided with}。

Preferably, in step 2) of the above method, the flue gas adsorbed and purified by the activated carbon in the adsorption tower is discharged through a chimney.

According to a second embodiment of the present invention, there is provided a flue gas purification system for achieving zero discharge of wastewater:

the system comprises an adsorption tower, wherein an adsorption tower active carbon inlet is formed in the top of the adsorption tower, and an adsorption tower active carbon outlet is formed in the bottom of the adsorption tower. The adsorption tower is also provided with an adsorption tower flue gas inlet. The flue gas inlet of the adsorption tower is connected with the original flue gas conveying pipeline. The original flue gas conveying pipeline is divided into bypass flue gas pipelines. An atomizer and a dust remover are sequentially arranged on the bypass flue gas pipeline. The atomizer is provided with a flue gas inlet, a flue gas outlet and a waste water inlet. The dust remover is provided with a gas inlet, a gas outlet and a solid outlet. The bypass flue gas pipeline passes through the atomizer and the dust remover and then is combined to the original flue gas conveying pipeline. The atomizer is disposed upstream of the dust separator.

A first booster fan is arranged on the original flue gas conveying pipeline. The first booster fan is arranged at the downstream of the position where the bypass flue gas pipeline is merged to the original flue gas conveying pipeline.

The original flue gas conveying pipeline is connected with an air pipeline. The air pipeline is connected between the position of the bypass flue gas pipeline separated from the original flue gas conveying pipeline and the position of the bypass flue gas pipeline combined to the original flue gas conveying pipeline.

The system also comprises an analysis tower, wherein the top of the analysis tower is provided with an analysis tower activated carbon inlet, and the bottom of the analysis tower is provided with an analysis tower activated carbon outlet. The desorption tower is also provided with a desorption gas outlet. The stripping gas outlet is connected to the scrubbing system. And a waste water outlet is arranged on the washing system and is connected to the atomizer.

Preferably, the system further comprises a bypass valve disposed on the bypass flue gas duct. The bypass valve is located upstream of the atomizer.

Preferably, the system further comprises a cold air valve disposed on the air duct.

In the invention, a first temperature measuring point is arranged at the upstream of the position of the bypass flue gas pipeline separated from the original flue gas conveying pipeline. And a second temperature measuring point is arranged between the position where the original flue gas conveying pipeline is connected with the air pipeline and the position where the bypass flue gas pipeline is combined to the original flue gas conveying pipeline. And a third temperature measuring point is arranged on the bypass flue gas pipeline and is positioned at the downstream of the dust remover. And a fourth temperature measuring point is arranged on the original flue gas conveying pipeline and at the downstream of the position where the bypass flue gas pipeline is combined to the original flue gas conveying pipeline.

Preferably, the system further comprises a waste water storage tank. The waste water outlet of the washing system is connected to a waste water storage tank. The waste water storage tank is connected to the waste water inlet of the atomizer through a waste water input pipeline. Preferably, a waste water pump is arranged on the waste water input pipeline. Preferably, a waste water temperature detection device is arranged in the waste water storage tank.

Preferably, the air duct is provided with an air temperature detecting device.

Preferably, a flow meter is arranged on the raw flue gas conveying pipeline and upstream of the first temperature measuring point.

Preferably, the bypass flue gas pipeline is provided with a second booster fan, and the second booster fan is arranged at the downstream of the dust remover.

Preferably, the system further comprises a first conveyor for conveying the activated carbon to be regenerated from the activated carbon outlet at the bottom of the adsorption tower to the activated carbon inlet at the top of the desorption tower. The system also comprises a second conveyor for conveying the regenerated activated carbon from an activated carbon outlet at the bottom of the desorption tower to an activated carbon inlet at the top of the adsorption tower.

Preferably, the system further comprises a chimney. The adsorption tower is provided with an adsorption tower smoke outlet, and the adsorption tower smoke outlet is connected to a chimney through a raw smoke conveying pipeline.

In the invention, the first booster fan is arranged on the raw flue gas conveying pipeline. The first booster fan is arranged to enable the flue gas to flow along the flue gas pipeline and enter the adsorption tower to provide power. Therefore, the specific position of the first booster fan arranged on the original flue gas conveying pipeline is not limited, and the requirement that the flue gas enters the adsorption tower to provide power can be met. For example, a first booster fan may be provided downstream of the location where the bypass flue gas duct merges into the raw flue gas delivery duct; or may be provided upstream of the point at which the raw flue gas duct merges into the raw flue gas duct.

In the invention, the second booster fan is arranged on a bypass flue gas pipeline which is branched from the original flue gas conveying pipeline. The second booster fan is arranged to provide power for the flue gas to enter the bypass flue gas pipeline. Correspondingly, the specific position of the second booster fan arranged on the bypass flue gas pipeline is not limited, and the requirement that power is provided for flue gas entering the bypass flue gas pipeline can be met. For example, a second booster fan may be provided downstream of the atomizer; or may be located upstream of the atomizer.

The invention relates to a flue gas purification method for realizing zero discharge of waste water, which comprises the steps of firstly, detecting the content of sulfur oxides in original flue gas, and calculating the waste water amount generated by a washing system for flue gas purification; then, the amount of the flue gas which needs to enter the bypass flue gas pipeline under the condition of processing the total amount of the waste water generated by the washing system is calculated out according to the formula (3) when the heat released by the flue gas is equal to the heat absorbed by the waste water when the heat exchange is carried out between the flue gas and the waste water in the bypass flue gas pipeline; then according to the heat released by the flue gas when the flue gas in the original flue gas conveying pipeline exchanges heat with cold airThe quantity is equal to the heat absorbed by the cold air, namely the quantity of the cold air which needs to be introduced into the original flue gas conveying pipeline is calculated by the formula (7); finally, the temperature T4 of the fourth temperature measuring point (namely the flue gas temperature at the inlet of the adsorption tower) is controlled to be at the target temperature T4 by adjusting the amount of the flue gas entering the bypass flue gas pipeline and the amount of the cold air introduced into the original flue gas conveying pipeline_{Is provided with}The range of + -t ℃, i.e. at 100 ℃ and 145 ℃, preferably at 110 ℃ and 140 ℃.

In the present invention, the specific heat capacity of each substance in the temperature range in the corresponding pipe is as follows:

specific heat capacity C of flue gas_{Cigarette with heating means}1.005-1.026 kJ/(kg ℃); heat of vaporization r of waste water_{Water (W)}2307.8-2457.7 kJ/kg; specific heat capacity of water vapor C_{Water vapour}1.864-1.930 kJ/(kg. DEG C); specific heat capacity C of cold air_{Qi (Qi)}1.005-1.009 kJ/(kg. DEG C); specific heat capacity C of mixed gas of flue gas and waste water₁1.009-1.032 kJ/(kg. DEG C); specific heat capacity C of mixed gas of flue gas and cold air₂＝1.009～1.017kJ/(kg·℃)。

In the invention, the dust remover is arranged at the downstream of the atomizer, and harmful substances in the wastewater can be discharged out of the whole system through the dust remover after being converted into salt substances, so that the harmful elements in the wastewater can be effectively prevented from corroding system equipment, and the problem that the wastewater can not be used as a water source for cooling flue gas in the prior art is solved.

In the invention, in the industries of steel, electric power, nonferrous metal, petrifaction, chemical industry or building materials and the like, because the used raw materials are various, the flue gas containing various pollutants is often generated, and the flue gas contains SO₂NOx, dust, VOCs, heavy metals, and the like. The multi-pollutant flue gas is subjected to adsorption treatment, and an adsorbent (such as activated carbon) adsorbing the multi-pollutants is subjected to desorption treatment and is recycled; in the process of desorption, the generated desorption gas is washed, a large amount of wastewater is generated in the washing process, and the desorption gas washing wastewater is not effectively treated, so that the environment is seriously polluted. The invention utilizes the heat of the original flue gas (such as the original sintering flue gas) to treat the waste water generated in the processes of desorption, desorption gas treatment and the like. The method has the advantages of co-processing and operation of flue gas and waste waterLow cost, low equipment investment, clean treatment, effective control of secondary pollution and zero discharge of waste water.

In the invention, all the wastewater to be treated is evaporated by the waste heat of the original flue gas, then is dedusted and is conveyed to the adsorption tower for treatment, thereby realizing zero discharge of the wastewater. The waste water is conveyed to an original flue gas conveying pipeline for treatment, but if all the original flue gas is mixed with the waste water, the waste water contains impurities such as metal ions, chloride ions, fluoride ions, sulfate ions and the like; the waste water and the flue gas can generate crystals after being mixed, and the crystals can be conveyed to an adsorption tower only after being subjected to dust removal treatment; otherwise, the flue gas of mixing this type of waste water will seriously influence the performance of active carbon in the adsorption tower for adsorption effect discounts greatly, will seriously make active carbon thoroughly inactivate, causes the waste of resource. If waste water and all flue gases are mixed and then undergo the dust removal process, the amount of the flue gases to be treated is large, so that the dust removal work in the whole process flow is greatly increased, the cost is increased, the investment of dust removal equipment is large, and the loss is larger.

Therefore, the invention divides the original flue gas conveying pipeline for conveying the high-temperature flue gas into the bypass flue gas pipeline, guides one part of the original flue gas into the bypass flue gas pipeline, dries and crystallizes the waste water through the flue gas in the bypass flue gas pipeline, and then conveys the mixed gas of the flue gas and the waste water after mixing the part of the waste water and the flue gas to the adsorption tower for subsequent treatment through dust removal treatment. According to the technical scheme, only part of flue gas used for mixing the wastewater and the mixed gas after the wastewater is atomized are treated, and the rest of flue gas which does not pass through the bypass flue gas pipeline does not need to be subjected to dust removal treatment, so that the workload of dust removal is greatly reduced, the energy is saved, and the investment is reduced.

According to the waste water amount to be treated, the amount of the flue gas entering the bypass flue gas pipeline is accurately controlled, so that the flue gas entering the bypass flue gas pipeline can just treat the part of waste water. If the flue gas introduced into the bypass flue gas pipeline is too little, the wastewater treatment is incomplete, and the significance of the invention is lost; if the flue gas that introduces bypass flue gas pipeline is too much, will make the flue gas in the bypass flue gas pipeline surplus, handle waste water and need not surplus flue gas, because the flue gas in the bypass flue gas pipeline all need handle through the dust remover, consequently, the too much work load that will increase the dust removal of flue gas that introduces bypass flue gas pipeline, and is also stricter to the requirement of dust remover, has increased the input cost. According to the invention, the amount of the flue gas introduced into the bypass flue gas pipeline is accurately controlled, so that the part of the flue gas can just treat the wastewater to be treated, and the extra workload of dust removal is not increased. And removing the flue gas introduced into the bypass flue gas pipeline, and directly conveying the residual part of the flue gas to the adsorption tower through the original flue gas conveying pipeline, wherein the part of the flue gas is cooled by adding cold air, so that the temperature of the flue gas at the inlet of the adsorption tower is regulated within a specified range.

If the temperature of the flue gas input into the adsorption tower is too low, the temperature condition of removing pollutants by the activated carbon cannot be achieved, so that the adsorption effect of the activated carbon is poor, and the aim of purifying the flue gas cannot be achieved; if the temperature of the flue gas input into the adsorption tower is too high, the activated carbon in the adsorption tower is inactivated due to high temperature, and the adsorption function is lost. Therefore, it is important to accurately control the flue gas temperature at the inlet of the adsorption tower. According to the invention, the temperature of the flue gas entering the adsorption tower is ensured to be adjusted within a proper range by accurately controlling the temperature of the flue gas of the bypass flue gas pipeline and the temperature of the flue gas of the original flue gas conveying pipeline.

In the invention, the original flue gas conveying pipeline for conveying the high-temperature flue gas is divided into the bypass flue gas pipeline, and the flue gas enters the adsorption tower through the original flue gas conveying pipeline and the bypass flue gas pipeline. The waste water is mixed with the flue gas in the bypass flue gas pipeline, so that the waste water is mixed with the flue gas to form flue gas and waste water mixed gas; the purpose of treating the wastewater is achieved. Because the wastewater contains metal ions, chloride ions, fluoride ions, sulfate ions and other substances, after the wastewater is conveyed to the bypass flue gas pipeline, the wastewater can be dried by utilizing the flue gas in the bypass flue gas pipeline, so that ions in the wastewater form crystal salt; such as chloride, fluoride, sulfate, and the like; in the mixed gas of the flue gas and the waste water after mixing, because ions are contained in the waste water before forming crystallized salt, the crystallized salt is discharged from a solid outlet of a dust remover through dust removal treatment; the crystallized salt is recovered and can be sold or used for other purposes, resulting in economic value. Therefore, the technical scheme of the invention not only treats the wastewater containing impurities, but also can recover by-product crystalline salt to generate economic value; in addition, the waste water sprayed into the bypass flue gas pipeline also plays a role in regulating the temperature of the flue gas entering the adsorption tower, so that the flue gas entering the adsorption tower is controlled within a temperature range suitable for activated carbon adsorption treatment. The flue gas in the original flue gas conveying pipeline is subjected to temperature regulation by adding cold air, so that the flue gas entering the adsorption tower is controlled within a temperature range suitable for activated carbon adsorption treatment.

In the invention, the heat quantity required by the wastewater treatment is calculated according to the quantity of the wastewater to be treated and the temperature of the flue gas entering the adsorption tower. The heat required by the wastewater treatment is provided by the flue gas in the bypass flue gas pipeline, and the amount of the flue gas entering the bypass flue gas pipeline can be accurately calculated according to the temperature of the original flue gas; therefore, through adjustment and control, the amount of the flue gas entering the bypass flue gas pipeline can just completely treat the wastewater, and the surplus condition can not exist, so that the load of dust removal treatment can not be additionally increased; in addition, through accurate control, the temperature of the flue gas entering the adsorption tower can be controlled within a temperature range suitable for activated carbon adsorption treatment.

In the invention, the raw flue gas is divided into two parts, and one part is used for treating wastewater through the bypass flue gas pipeline; the other part is conveyed to the adsorption tower through a raw flue gas conveying pipeline. The temperature of the flue gas entering the adsorption tower is controlled by the temperature of the flue gas conveyed by the original flue gas conveying pipeline, and the temperature of the flue gas is adjusted by adding cold air. According to the technical scheme, the heat quantity to be released by the part of flue gas can be calculated according to the temperature of the original flue gas, the flue gas quantity in the pipeline and the temperature of the flue gas entering the adsorption tower. The released heat is treated by the added cold air, and the amount of the cold air needing to be added can be accurately calculated according to the temperature of the cold air, so that the temperature of the flue gas entering the adsorption tower is controlled within the temperature range suitable for the adsorption treatment of the activated carbon. If too much cold air is added, the temperature of the flue gas entering the adsorption tower is too low, and the adsorption effect is influenced; if the added cold air is too little, the temperature of the flue gas entering the adsorption tower is too high, and the activated carbon in the adsorption tower is inactivated due to high temperature, even loses the adsorption function. Therefore, the amount of the added cold air needs to be accurately controlled, and the stability, the high efficiency and the smoothness of the subsequent process can be ensured.

In the invention, the amount of flue gas entering the bypass flue gas pipeline can be adaptively adjusted according to the amount of the wastewater to be treated. Meanwhile, the amount of added cold air and the amount of flue gas entering the bypass flue gas pipeline can be adaptively adjusted according to the temperature of the flue gas entering the adsorption tower.

In the invention, the temperature of the mixed gas of the flue gas and the waste water after the waste water and the flue gas in the bypass flue gas pipeline are mixed can be set to the temperature required by the flue gas entering the adsorption tower, the temperature of the mixed gas of the flue gas and the cold air after the flue gas and the cold air in the original flue gas conveying pipeline are also set to the temperature required by the flue gas entering the adsorption tower, and the two paths of gases are mixed, the temperature is unchanged and are conveyed to the adsorption tower, so that the temperature of the flue gas entering the adsorption tower is controlled within the temperature range suitable for the adsorption treatment of the activated carbon. It can also be: the temperature of the flue gas and the waste water mixed gas after the waste water and the flue gas are mixed in the bypass flue gas pipeline is set to be lower than the temperature required by the flue gas entering the adsorption tower, the temperature of the flue gas and the cold air mixed gas after the flue gas and the cold air are mixed in the original flue gas conveying pipeline is set to be higher than the temperature required by the flue gas entering the adsorption tower, calculation is carried out according to the flue gas amount in the two flue gas pipelines by the formula (10), and after the flue gas in the two flue gas pipelines is mixed, the temperature of the flue gas entering the adsorption tower is controlled within the temperature range suitable for active carbon adsorption treatment. The method can also be as follows: setting the temperature of the flue gas and the waste water mixed gas after the waste water and the flue gas are mixed in the bypass flue gas pipeline to be higher than the temperature required by the flue gas entering the adsorption tower, setting the temperature of the flue gas and the cold air mixed gas after the flue gas and the cold air are mixed in the original flue gas conveying pipeline to be lower than the temperature required by the flue gas entering the adsorption tower, calculating according to the flue gas amount in the two flue gas pipelines by using a formula (10), and ensuring the temperature control of the flue gas entering the adsorption tower after the flue gas in the two flue gas pipelines is mixedIs prepared in a temperature range suitable for the adsorption treatment of the active carbon. In addition, according to the technical scheme of the invention, on the premise of completely treating the wastewater, T2 is adjusted according to the smoke volume in the bypass smoke pipeline and the smoke volume in the original smoke conveying pipeline_{Is provided with}And T3_{Is provided with}The temperature value ensures that the temperature of the flue gas entering the adsorption tower is controlled within the temperature range suitable for the adsorption treatment of the activated carbon after the two paths of flue gas are mixed, namely T4 is regulated or controlled at T4_{Is provided with}The range of +/-t ℃.

In the invention, the flue gas temperature T2 in the flue at the corresponding position is detected to be higher than T2 on line according to the second temperature measuring point_{Is provided with}Increasing the amount of cold air introduced into the original flue gas conveying pipeline; if T2 is lower than T2_{Is provided with}The amount of cold air introduced into the raw flue gas duct is reduced. Detecting that the temperature T3 of the flue gas in the flue at the corresponding position is higher than T3 on line according to the third temperature measuring point_{Is provided with}The amount of flue gas entering the bypass flue gas pipeline is reduced; if T3 is lower than T3_{Is provided with}The amount of flue gas entering the bypass flue gas duct is increased. Detecting that the temperature T4 of the flue gas in the flue at the corresponding position is higher than T4 on line according to the fourth temperature measuring point_{Is provided with}Increasing the amount of cold air introduced into the original flue gas conveying pipeline, and/or reducing the amount of flue gas entering the bypass flue gas pipeline on the premise of completely treating wastewater; if T4 is lower than T4_{Is provided with}The amount of cold air introduced into the original flue gas conveying pipeline is reduced, and/or the amount of flue gas entering the bypass flue gas pipeline is properly increased on the premise that wastewater can be completely treated.

In the invention, after the analytic gas passes through the washing system, the generated wastewater is conveyed to the bypass flue gas pipeline, and the waste heat in the bypass flue gas pipeline is used for drying, so that metal ions, chloride ions, fluoride ions and sulfate ions in the wastewater form crystallized salt after being dried by flue gas, and the crystallized salt can generate direct economic value. The technical scheme of the invention can realize the recycling of the wastewater, realize the zero discharge of the wastewater, and simultaneously can recover byproducts, thereby generating economic value.

In the actual process production process, the amount of wastewater generated by the whole system can be calculated by detecting the content of sulfur oxides in the raw flue gas; according to the amount of the waste water, the required amount of the flue gas in the bypass flue gas pipeline can be accurately calculated; further, the amount of cold air required to be added into the original flue gas pipeline can be accurately calculated.

In the invention, the wastewater is obtained from SRG gas generated by activated carbon thermal regeneration, and is subjected to wet washing by a wet washing device to obtain high-sulfur gas and acidic washing wastewater. Wherein: the high-sulfur gas is subjected to a sulfur resource recycling process to recover sulfur resources. Preferably, the acidic washing wastewater is subjected to acidic filtration to obtain clear liquid and carbon powder. The clear liquid is conveyed to a bypass flue gas pipeline.

Preferably, alkali liquor is added into the obtained clear liquid, the clear liquid is atomized by an atomizer, the mixture of the atomized clear liquid and the alkali liquor is input into a flue gas conveying pipeline to be dried by flue gas, then crystallization is carried out, the flue gas is dedusted by a deduster, and simultaneously (trapped) crystallized salt is obtained.

In the invention, the acidic flue gas washing wastewater comprises one or more of suspended matters, metal ions, ammonia nitrogen, fluorine and chlorine and organic pollutants. Preferably, the metal ions are one or more of iron, copper, lead, calcium, zinc, cadmium, cobalt, nickel and aluminum.

In the invention, the acidic filtration is to remove suspended matters by utilizing the self gravity settling action or the interception action of a filter. The concentration of suspended matters in the clear liquid after acidic filtration is 0-100 mg/L, preferably 1-80 mg/L, and more preferably 2-50 mg/L.

In the invention, the atomization is that the mixture of clear liquid and alkali liquor is dispersed into small fog drops through an atomizer, and the particle size of the small fog drops is 10-100 μm, preferably 15-80 μm, and more preferably 20-50 μm.

Preferably, the step of inputting the mixture of the atomized clear liquid and the alkali liquor into a bypass flue gas pipeline for drying specifically comprises the following steps: and (3) inputting the mixture of the atomized clear liquid and the alkali liquor into a bypass flue gas pipeline, drying and crystallizing the flue gas in the bypass flue gas pipeline, then dedusting the flue gas by a deduster, and discharging crystallized salt from a solid outlet of the deduster to obtain the crystallized salt. Preferably, the atomized mixture of the clear liquid and the alkali liquor can be dried by using the flue gas in the flue gas conveying pipeline; the flue gas in the bypass separated by the flue gas conveying pipeline is dried, then the mixed gas of the flue gas in the bypass separated by the flue gas conveying pipeline and the mixture of the clear liquid and the alkali liquor passes through the dust remover, the crystallized salt is solid, and the crystallized salt is discharged from a solid outlet of the dust remover.

In the invention, the alkali liquor is one or more of soluble hydroxide, soluble carbonate and soluble bicarbonate, and is preferably sodium hydroxide. More preferably 30% liquid caustic.

Preferably, the addition amount (volume) of the alkali liquor is 0 to 0.5 times, preferably 0.01 to 0.25 times, and more preferably 0.05 to 0.1 times of the amount (volume) of the clear liquid.

In the invention, the dust removal treatment adopts dry dust removal, preferably one of electric dust removal, cloth bag dust removal and ceramic dust removal, and more preferably cloth bag dust removal.

In the invention, in the atomization process, the ratio of the smoke gas amount to the wastewater atomization amount is 1000: 1-2000: 1, and preferably 1500: 1-1800: 1.

Cleaning, evaporating and crystallizing wastewater: after suspended matters are removed from the wastewater through acidic filtration, the wastewater is changed into small-particle acidic fog drops through an atomizer, and the acidic fog drops are in contact with atomized alkali liquor quickly and have neutralization reaction to form neutral or weakly alkaline liquid drops due to small particle size, large specific surface area and high mass transfer rate, and the flue gas heat is absorbed quickly to realize drying crystallization. In the process of droplet crystallization, because the liquid drops are adjusted to be neutral or alkalescent in advance, precipitation reaction can occur in the liquid drops to form alkali salt, which provides crystal nuclei for the growth of dried crystals, thereby being beneficial to the formation of large-particle crystal salt and being convenient for the filtration and recovery of the crystal salt.

In the present invention, the desorption gas, i.e. SRG gas, is washed by wet method, so that a part of carbon powder attached in the SRG gas enters the wastewater along with the desorption gas, and metal ions are dissolved in the water. The sulfur-containing gas is still gaseous, the high-sulfur gas is collected, sulfur resources are recovered through a sulfur resource recycling process, and the remaining extremely small part of sulfur-containing tail gas is conveyed to a flue gas conveying pipeline and then treated by an adsorption tower. Realizing zero emission of the polluted gas.

In the invention, after wet washing, the generated acidic washing wastewater comprises carbon powder and metal ions in a suspended state; the part of the acidic washing wastewater is subjected to acidic filtration to separate suspended matters (namely carbon powder) in the wastewater to obtain carbon powder, and the part of the carbon powder can be recycled through a carbon powder recycling process, for example, a re-granulation process is adopted to obtain large-particle activated carbon, and then the large-particle activated carbon is recycled to an adsorption tower. The wastewater after the suspended matter is separated contains metal ions (or metal salts) which are clear liquid; adding an alkali solution into the clear liquid, atomizing, drying by using heat emitted by a flue gas conveying pipeline, and crystallizing the metal ion solution after drying to generate metal crystallized salt; the metal crystalline salt can be sold or used for other purposes, resulting in economic value. And adding alkali liquor into the clear liquid to form a clear liquid and alkali liquor mixture, drying the clear liquid and the alkali liquor mixture in a flue gas conveying pipeline by using the waste heat of the flue gas, forming crystals by metal ions, chloride ions, fluoride ions, sulfate ions and the like, collecting the crystals by a dust remover, and recovering crystallized salt.

In the invention, the wastewater is obtained from SRG gas generated by activated carbon thermal regeneration, and is subjected to wet washing by a wet washing device to obtain high-sulfur gas and acidic washing wastewater. Wherein: the high-sulfur gas is subjected to a sulfur resource recycling process to recover sulfur resources. Preferably, the acidic washing wastewater is subjected to acidic filtration to obtain clear liquid and carbon powder. And adding mixed alkali into the obtained clear liquid to flocculate and precipitate the clear liquid, thereby obtaining the metal-containing sludge and the salt-containing wastewater. Adding alkali liquor into the obtained salt-containing wastewater, atomizing by an atomizer, inputting a mixture of the atomized clear liquid and the alkali liquor into a flue gas conveying pipeline to be dried by flue gas, crystallizing, and removing dust from the flue gas by a dust remover to obtain crystallized salt.

Preferably, mixed alkali is added into the obtained clear liquid, the pH of the clear liquid is adjusted to be alkalescent, and the metal-containing sludge and the salt-containing wastewater are obtained through weak alkali flocculation precipitation. Preferably, the pH of the serum is adjusted to 7-10, preferably 7.2-9, more preferably 7.5-8.5.

In the invention, the mixed alkali is OH-containing^-And CO₃ ^2-A mixture of constituents, or containing OH^-And HCO₃ ^-A mixture of components. Preferably, the mixed base is a mixture of a lyotropic hydroxide and a lyotropic carbonate, or a mixture of a lyotropic hydroxide and a lyotropic bicarbonate. More preferably, the mixed alkali is a mixture of one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide and one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.

In the present invention, the wet scrubbing is carried out using an acidic solution (e.g., a 0.5-10% strength dilute hydrochloric acid or dilute sulfuric acid or dilute phosphoric acid solution; the strength is, for example, 1 wt%, 4 wt%, 5 wt%, or 7 wt%). Preferably, the pH value of the acidic solution is 0 to 7, preferably 1 to 6, and more preferably 2 to 5. In the wet washing process, the volume flow ratio of the SRG gas to the acidic solution is 1: 10-100, preferably 1: 20-80, and more preferably 1: 30-60.

In the invention, after wet washing, the generated acidic washing wastewater comprises carbon powder and metal ions in a suspended state; the part of the acidic washing wastewater is subjected to acidic filtration to separate suspended matters (namely carbon powder) in the wastewater to obtain carbon powder, and the part of the carbon powder can be recycled through a carbon powder recycling process, for example, a re-granulation process is adopted to obtain large-particle activated carbon, and then the large-particle activated carbon is recycled to an adsorption tower. The wastewater after the suspended matter is separated contains metal ions (or metal salts) which are clear liquid; and (3) subjecting the clear liquid to a flocculation precipitation process, adding mixed alkali into the clear liquid to enable most heavy metal ions in the clear liquid to form precipitates, introducing the precipitates into the metal-containing sludge, and then recovering metals from the metal-containing sludge to obtain a pure metal recovered material which can be sold or used for other purposes. Adding an alkali solution into the salt-containing wastewater obtained through the flocculation precipitation procedure, atomizing the salt-containing wastewater, inputting the atomized salt-containing wastewater into a flue gas conveying pipeline, and drying the atomized salt-containing wastewater by using the waste heat of argon gas, wherein metal ions, chloride ions, fluoride ions, sulfate ions and the like which are not precipitated in the flocculation precipitation procedure are crystallized in the salt-containing wastewater after drying to generate metal crystallized salt; the metal crystalline salt can be sold or used for other purposes, resulting in economic value. And adding alkali liquor into the salt-containing wastewater to form a clear solution, drying the mixture of the clear solution and the alkali liquor in a flue gas conveying pipeline, forming crystals by metal ions, chloride ions, fluoride ions, sulfate ions and the like, collecting the crystals by a dust remover, and recovering crystallized salt.

In the invention, the SRG gas refers to the enriched flue gas discharged after being analyzed by the desorption tower. The SRG gas (or SRG flue gas) has high temperature, high dust content and SO₂High content, high water content, complex smoke impurity components and the like. In the art, SRG gas is also referred to simply as sulfur-rich gas; used for being conveyed to an acid making system for making acid.

In the invention, the amount of the flue gas entering the bypass flue gas pipeline is calculated according to the amount of the wastewater to be treated. In an actual operation process, the flue gas and the waste water of the bypass flue gas pipeline are often synchronously conveyed to the bypass flue gas pipeline; according to the amount of the waste water and the amount of the flue gas entering the bypass flue gas pipeline, the speed of the waste water entering the bypass flue gas pipeline and the speed of the flue gas entering the bypass flue gas pipeline are adjusted, so that the flue gas entering the bypass flue gas pipeline can just completely treat the waste water, and zero discharge of the waste water is realized. The speed of the waste water input into the bypass flue gas pipeline is controlled by a waste water pump. The rate of flue gas entering the bypass flue gas duct is controlled by a bypass valve.

In the present application, "upstream" and "downstream" are set according to the direction of the flow of the flue gas in the duct. The "top" and "bottom" are set according to the height direction of the apparatus or device.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the method and the system, the original flue gas conveying pipeline is adopted to divide the bypass flue gas pipeline, the waste water generated by the gas analyzed by the analysis tower through the washing system is completely sprayed into the bypass flue gas pipeline, the bypass flue gas is cooled, and meanwhile, the waste water is dedusted, so that the accurate control of the flue gas temperature is realized, the waste water generated by the flue gas purification washing system is reasonably treated, and the zero discharge of the waste water of the whole system is really realized;

2. according to the invention, flue gas in the bypass flue gas pipeline is sprayed into waste water to be cooled, flue gas in the original flue gas conveying pipeline is cooled by introducing cold air, two paths of flue gas after being cooled are mixed, and the flue gas temperature is accurately controlled finally according to the condition that the heat absorbed by low-temperature substances is equal to the heat emitted by high-temperature substances in the heat exchange processes for several times;

3. the bypass flue gas is sprayed into the waste water to cool, and the waste water is evaporated by using the waste heat of the flue gas, so that the energy waste is reduced; the waste water which is generated by the flue gas purification system and is difficult to treat originally is also reasonably treated, so that the cost input of waste water treatment is reduced; meanwhile, the amount of supplemented air is reduced, and the operating cost of a flue gas purification system is reduced;

4. the method and the device are simple to operate, complex pipeline equipment and reaction devices are not required to be invested, the whole system is stable to operate, and the investment cost is low.

Drawings

FIG. 1 is a flow chart of a process for cooling flue gas in the prior art;

FIG. 2 is a process flow diagram of the flue gas purification method of the present invention for realizing zero discharge of wastewater;

FIG. 3 is a schematic diagram of a flue gas purification system for achieving zero wastewater discharge according to the present invention;

FIG. 4 is a schematic diagram of another configuration of a flue gas purification system for achieving zero wastewater discharge according to the present invention;

FIG. 5 is a second process flow diagram of the flue gas purification method for realizing zero discharge of wastewater according to the present invention;

FIG. 6 is a third process flow diagram of the flue gas purification method for realizing zero discharge of wastewater.

Reference numerals: 1: an adsorption tower; 101: a flue gas inlet of the adsorption tower; 102: a flue gas outlet of the adsorption tower; 2: an atomizer; 201: a flue gas inlet; 202: a flue gas outlet; 203: a wastewater inlet; 3: a dust remover; 301: a gas inlet; 302: a gas outlet; 303: a solids outlet; 4: a waste water storage tank; 5: a waste water pump; 6: a bypass valve; 7: a flow meter; 8: a cold air valve; 9: a chimney; 10: a first booster fan; 11: a wastewater temperature detection device; 12: an air temperature detection device; 13: a second booster fan; 14: a resolution tower; 1401: a desorption gas outlet; 15: a washing system; 1501: a waste water outlet; 16: a first conveyor; 17: a second conveyor;

l1: an original flue gas conveying pipeline; l2: a bypass flue gas duct; l3: a wastewater input pipeline; l4: an air duct;

p1: a first temperature measuring point; p2: a second temperature measurement point; p3: a third temperature measurement point; p4: and a fourth temperature measuring point.

Detailed Description

1) a raw flue gas conveying pipeline L1 for conveying high-temperature flue gas to the activated carbon adsorption tower 1 is divided into a bypass flue gas pipeline L2, and the raw flue gas enters the adsorption tower 1 through a raw flue gas conveying pipeline L1 and a bypass flue gas pipeline L2;

2) the flue gas enters an activated carbon adsorption tower 1, is adsorbed and purified by activated carbon in the adsorption tower 1 and then is discharged, and the activated carbon adsorbing pollutants in the flue gas is discharged from the bottom of the adsorption tower 1;

3) transferring the active carbon adsorbed with the pollutants into an analytical tower 14 from the bottom of the adsorption tower 1, analyzing and regenerating the active carbon adsorbed with the pollutants, discharging the analyzed and regenerated active carbon from the bottom of the analytical tower 14, and transferring the active carbon into the adsorption tower 1; the desorbed gas enters a washing system 15, and the washing system 15 washes the desorbed gas and generates wastewater;

① temperature control of flue gas of the bypass flue gas pipeline L2, wherein the bypass flue gas pipeline L2 is provided with an atomizer 2, the waste water generated by the washing system 15 is atomized by the atomizer 2 and then mixed with the flue gas in the bypass flue gas pipeline L2, and the waste water exchanges heat with the flue gas entering the bypass flue gas pipeline L2 to form mixed gas of the flue gas and the waste water;

② temperature control of flue gas in the original flue gas conveying pipeline L1, namely, introducing cold air into the original flue gas conveying pipeline L1 to regulate the temperature of the flue gas in the original flue gas conveying pipeline L1 at the downstream of the position where the original flue gas conveying pipeline L1 branches out of the bypass flue gas pipeline L2;

③ the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline L2 is merged into the original flue gas conveying pipeline L1, and is mixed with the flue gas in the original flue gas conveying pipeline L1 after the temperature is controlled or adjusted by cold air, and then the mixed gas enters the adsorption tower 1, and the temperature of the flue gas at the inlet of the adsorption tower 1 is adjusted within the specified range.

Preferably, in step 1) of the above method, a first temperature measurement point P1 is provided upstream of the point at which the raw flue gas duct L1 branches off the bypass flue gas duct L2. A second temperature measurement point P2 is provided between the point at which the raw flue gas duct L1 is fed with cold air and the point at which the bypass flue gas duct L2 merges into the raw flue gas duct L1. A third temperature measuring point P3 is provided on the bypass flue gas duct L2 and downstream of the precipitator 3. A fourth temperature measuring point P4 is provided on the raw flue gas duct L1 downstream of the point where the bypass flue gas duct L2 merges into the raw flue gas duct L1. The first temperature measuring point P1 detects the flue gas temperature T1 in the flue at the corresponding position on line. The second temperature measuring point P2 detects the flue gas temperature T2 in the flue at the corresponding position on line. The third temperature measuring point P3 detects the flue gas temperature T3 in the flue at the corresponding position on line. The fourth temperature measuring point P4 detects the flue gas temperature T4 in the flue at the corresponding position on line. Wherein the target or set temperature value at the fourth temperature measurement point P4 is T4_{Is provided with}。

According to the heat Q released by the flue gas entering the bypass flue gas pipeline L2_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct L2_{Water (W)}And equalising, calculating and adjusting the amount of flue gas entering the bypass flue gas duct L2 in sub-step ①, further dependent on the heat Q released by the flue gas entering the adsorption tower 1 through the raw flue gas duct L1_{Cigarette 2}Heat Q absorbed by cold air introduced into the raw flue gas duct L1_{Qi (Qi)}And (3) equally calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline L1 in the substep ②The amount of the smoke entering the bypass smoke pipeline L2 and the amount of the cold air introduced into the raw smoke conveying pipeline L1 enable the temperature T4 of the fourth temperature measuring point P4 to be adjusted or controlled at T4_{Is provided with}A temperature range of + -t deg.C, wherein t deg.C is in the range of 2-10 deg.C.

Preferably, the target or set temperature value T4 at the fourth temperature measuring point P4_{Is provided with}The temperature is preferably in the range of 100-145 ℃, preferably 110-140 ℃. I.e., the temperature of the flue gas at the inlet of the adsorption column 1 is adjusted within a prescribed range, for example, within the range of 100 ℃ and 145 ℃, preferably within the range of 110 ℃ and 140 ℃.

Preferably, step 1) of the method further includes detecting the content of sulfur oxides in the raw flue gas, and calculating the amount of wastewater generated by the scrubbing system 15 according to the content of sulfur oxides in the raw flue gas, specifically:

the flow meter 7 upstream of the first temperature measurement point P1 measures the total amount of flue gas as M₀Detecting SO in the original flue gas₂In a concentration of

Whereby the amount of wastewater M produced by the washing system 15_{Water (W)}Comprises the following steps:

Unit mg/Nm³；k₁Is a constant, and has a value of 0.9 to 1.6.

Preferably, in step 3) of the above method, the wastewater produced by the washing system 15 is stored in the wastewater tank 4. Wastewater enters the atomizer 2 from the wastewater storage tank 4 along a wastewater input line L3. Preferably, the wastewater in the wastewater storage tank 4 is neutral or alkaline. Preferably, a waste water pump 5 is arranged on the waste water input pipeline L3, and the waste water pump 5 provides power for the waste water to enter the atomizer 2.

Preferably, in sub-step ② of the above method, the cool air is delivered from the air duct L4 to the raw flue gas delivery duct L1.

Preferably, said heat Q released according to the fumes entering the bypass fume duct L2_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct L2_{Water (W)}And (3) equally, calculating and adjusting the amount of the flue gas entering the bypass flue gas pipeline L2 in the substep ①, specifically:

the first temperature measuring point P1 detects the temperature of the original flue gas as T1, and the temperature of the mixed gas of the flue gas and the waste water at the position of the third temperature measuring point P3 is set as T3_{Is provided with}Wherein: t3_{Is provided with}The temperature is 100-160 ℃, and the value is preferably within the range of 110-140 ℃;

a) calculating the heat required by wastewater treatment: the amount of wastewater produced by the washing system 15 is M_{Water (W)}Detecting the initial temperature of the wastewater as T_{Water (W)}And thus the heat Q to be absorbed for treating the waste water produced by the washing system 15_{Water (W)}Comprises the following steps:

b) the required flue gas volume of the bypass flue gas pipeline L2 is calculated: the amount of the flue gas entering the bypass flue gas pipeline L2 is set as M₁Whereby the heat Q released by the flue gas entering the bypass flue gas duct L2_{Cigarette 1}Comprises the following steps:

heat Q released by the flue gas entering the bypass flue gas duct L2_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct L2_{Water (W)}Equality, we can get:

Obtaining the following components:

The opening degree of the bypass valve 6 on the bypass flue gas pipeline L2 is adjusted so that the amount of the flue gas entering the bypass flue gas pipeline L2 is M₁。

Preferably, said heat Q further released according to the flue gas entering the adsorption tower 1 through the raw flue gas duct L1_{Cigarette 2}Heat Q absorbed by cold air introduced into the raw flue gas duct L1_{Qi (Qi)}And (3) equally, calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline L1 in the substep ②, specifically:

the flow meter 7 upstream of the first temperature measurement point P1 measures the total amount of flue gas as M₀The first temperature measuring point P1 detects the temperature of the original smoke as T1, and the temperature of the mixed gas of the smoke and the cold air at the position of the second temperature measuring point P2 is set as T2_{Is provided with}Wherein: t2_{Is provided with}The temperature is 100-160 ℃, and the value is preferably within the range of 110-140 ℃;

a) calculating the heat quantity required to be released by the raw flue gas in the raw flue gas conveying pipeline L1: the amount of the flue gas introduced into the adsorption tower 1 through the raw flue gas transfer duct L1 is (M)₀-M₁) The heat Q released by the flue gas entering the adsorption tower 1 through the raw flue gas duct L1_{Cigarette 2}Comprises the following steps:

b) The amount of cold air introduced into the original flue gas conveying pipeline L1 is calculated: the quantity of cold air introduced into the original flue gas conveying pipeline L1 is set as M_{Qi (Qi)}Measuring the initial temperature of the cold air as T_{Qi (Qi)}Accordingly, the heat Q absorbed by the cold air introduced into the raw flue gas duct L1_{Qi (Qi)}Comprises the following steps:

C in formula (6)_{Qi (Qi)}Is the specific heat capacity of the cold air;

the heat Q released by the flue gas entering the adsorption column 1 through the raw flue gas duct L1_{Cigarette 2}Heat Q absorbed by cold air introduced into the raw flue gas duct L1_{Qi (Qi)}Equality, we can get:

Obtaining the following components:

The opening degree of a cold air valve 8 on the air pipeline L4 is adjusted, so that the quantity of cold air introduced into the original flue gas conveying pipeline L1 is M_{Qi (Qi)}。

Preferably, the temperature T4 of the fourth temperature measuring point P4 is adjusted or controlled at T4 by adjusting the amount of flue gas entering the bypass flue gas duct L2 and the amount of cold air passing into the raw flue gas conveying duct L1_{Is provided with}The range of +/-t ℃ is as follows:

the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline L2 is mixed with the mixed gas of the flue gas and the cold air in the original flue gas conveying pipeline L1 after the temperature of the flue gas and the cold air is controlled or regulated by the cold air, after the two paths of gases exchange heat, the temperature T4 of a fourth temperature measuring point P4 is regulated or controlled at T4_{Is provided with}The range of +/-t ℃. The heat Q absorbed (or released) by the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline L2_{Smoke and water}The heat Q released (or absorbed) by the mixed gas of the flue gas and the cold air in the raw flue gas conveying pipeline L1_{Smoke and gas}Equal, i.e.:

Q_{smoke and water}＝Q_{Smoke and gas}(9)，

Preferably, the flue gas temperature T2 in the flue at the corresponding position is detected on line according to the second temperature measuring point P2. If T2 equals T2_{Is provided with}Continuing to operate; t2 not equal to T2_{Is provided with}The quantity of cold air introduced into the original flue gas duct L1 is adjusted so that T2 equals T2_{Is provided with}。

And detecting the flue gas temperature T3 in the flue at the corresponding position on line according to a third temperature measuring point P3. If T3 equals T3_{Is provided with}Continuing to operate; t3 not equal to T3_{Is provided with}Adjusting the amount of flue gas entering the bypass flue gas duct L2 such that T3 equals T3_{Is provided with}。

And detecting the flue gas temperature T4 in the flue at the corresponding position on line according to a fourth temperature measuring point P4. If T4 equals T4_{Is provided with}Continuing to operate; t4 not equal to T4_{Is provided with}The amount of cold air passing into the original flue gas duct L1 and the amount of flue gas entering the bypass flue gas duct L2 are adjusted so that T4 equals T4_{Is provided with}。

Preferably, in step 2) of the above method, the flue gas adsorbed and purified by the activated carbon in the adsorption tower 1 is discharged through a chimney 9.

the system comprises an adsorption tower 1, wherein an adsorption tower active carbon inlet is formed in the top of the adsorption tower 1, and an adsorption tower active carbon outlet is formed in the bottom of the adsorption tower 1. The adsorption tower 1 is also provided with an adsorption tower flue gas inlet 101. The adsorption tower flue gas inlet 101 is connected with a raw flue gas conveying pipeline L1. The original flue gas conveying pipeline L1 branches into a bypass flue gas pipeline L2. The bypass flue gas pipeline L2 is sequentially provided with an atomizer 2 and a dust remover 3. The atomizer 2 is provided with a flue gas inlet 201, a flue gas outlet 202 and a waste water inlet 203. The dust remover 3 is provided with a gas inlet 301, a gas outlet 302 and a solid outlet 303. The bypass flue gas pipeline L2 passes through the atomizer 2 and the dust remover 3 and then is combined to the original flue gas conveying pipeline L1. The atomizer 2 is arranged upstream of the dust separator 3.

The original flue gas conveying pipeline L1 is provided with a first booster fan 10. The first booster fan 10 is disposed downstream of the point where the bypass flue gas duct L2 merges into the raw flue gas duct L1.

An air pipeline L4 is connected to the original flue gas conveying pipeline L1. The air duct L4 is connected between the point at which the raw flue gas duct L1 branches off the bypass flue gas duct L2 and the point at which the bypass flue gas duct L2 merges into the raw flue gas duct L1.

The system also comprises an analysis tower 14, wherein the top of the analysis tower 14 is provided with an analysis tower activated carbon inlet, and the bottom of the analysis tower 14 is provided with an analysis tower activated carbon outlet. The desorption tower 14 is further provided with a desorption gas outlet 1401, and the desorption gas outlet 1401 is connected to the washing system 15. The washing system 15 is provided with a waste water outlet 1501, and the waste water outlet 1501 is connected to the atomizer 2.

Preferably, the system further comprises a bypass valve 6 disposed on the bypass flue gas duct L2. The bypass valve 6 is located upstream of the atomizer 2.

Preferably, the system further comprises a cold air valve 8 disposed on the air duct L4.

In the present invention, a first temperature measurement point P1 is provided upstream of the point at which the raw flue gas duct L1 branches into the bypass flue gas duct L2. A second temperature measurement point P2 is provided between the location where the raw flue gas duct L1 joins the air duct L4 and the location where the bypass flue gas duct L2 merges into the raw flue gas duct L1. A third temperature measuring point P3 is provided on the bypass flue gas duct L2 and downstream of the precipitator 3. A fourth temperature measuring point P4 is provided on the raw flue gas duct L1 downstream of the point where the bypass flue gas duct L2 merges into the raw flue gas duct L1.

Preferably, the system further comprises a waste water storage tank 4. The waste water outlet 1501 of the scrubbing system 15 is connected to the waste water tank 4. The waste water tank 4 is connected to the waste water inlet 203 of the atomizer 2 through a waste water input line L3. Preferably, a waste water pump 5 is arranged on the waste water input pipeline L3. Preferably, a waste water temperature detecting device 11 is provided in the waste water storage tank 4.

Preferably, the air duct L4 is provided with an air temperature detecting device 12.

Preferably, a flow meter 7 is provided on the raw flue gas delivery line L1 upstream of the first temperature measurement point P1.

Preferably, a second booster fan 13 is arranged on the bypass flue gas duct L2, and the second booster fan 13 is arranged downstream of the dust separator 3.

Preferably, the system further comprises a first conveyor 16 for conveying the activated carbon to be regenerated from the activated carbon outlet at the bottom of the adsorption tower 1 to the activated carbon inlet at the top of the desorption tower 14. The system further comprises a second conveyor 17 for conveying the regenerated activated carbon from the activated carbon outlet at the bottom of the desorption tower 14 to the activated carbon inlet at the top of the adsorption tower 1.

Preferably, the system further comprises a chimney 9. The adsorption tower 1 is provided with an adsorption tower flue gas outlet 102, and the adsorption tower flue gas outlet 102 is connected to the chimney 9 through an original flue gas conveying pipeline L1.

Example 1

As shown in figure 3, a flue gas purification system for realizing zero discharge of waste water, the system comprises an adsorption tower 1, the top of the adsorption tower 1 is provided with an adsorption tower activated carbon inlet, and the bottom of the adsorption tower 1 is provided with an adsorption tower activated carbon outlet. The adsorption tower 1 is also provided with an adsorption tower flue gas inlet 101. The adsorption tower flue gas inlet 101 is connected with a raw flue gas conveying pipeline L1. The original flue gas conveying pipeline L1 branches into a bypass flue gas pipeline L2. The bypass flue gas pipeline L2 is sequentially provided with an atomizer 2 and a dust remover 3. The atomizer 2 is provided with a flue gas inlet 201, a flue gas outlet 202 and a waste water inlet 203. The dust remover 3 is provided with a gas inlet 301, a gas outlet 302 and a solid outlet 303. The bypass flue gas pipeline L2 passes through the atomizer 2 and the dust remover 3 and then is combined to the original flue gas conveying pipeline L1. The atomizer 2 is arranged upstream of the dust separator 3.

The system also includes a bypass valve 6 disposed on the bypass flue gas duct L2. The bypass valve 6 is located upstream of the atomizer 2. The system also includes a cold air valve 8 disposed on air duct L4.

A first temperature measurement point P1 is provided upstream of the point at which the raw flue gas duct L1 branches off the bypass flue gas duct L2. A second temperature measurement point P2 is provided between the location where the raw flue gas duct L1 joins the air duct L4 and the location where the bypass flue gas duct L2 merges into the raw flue gas duct L1. A third temperature measuring point P3 is provided on the bypass flue gas duct L2 and downstream of the precipitator 3. A fourth temperature measuring point P4 is provided on the raw flue gas duct L1 downstream of the point where the bypass flue gas duct L2 merges into the raw flue gas duct L1.

The system also includes a waste water storage tank 4. The waste water outlet 1501 of the scrubbing system 15 is connected to the waste water tank 4. The waste water tank 4 is connected to the waste water inlet 203 of the atomizer 2 through a waste water input line L3. A waste water pump 5 is arranged on the waste water input pipeline L3. A waste water temperature detection device 11 is arranged in the waste water storage tank 4.

The air duct L4 is provided with an air temperature detection device 12.

A flowmeter 7 is arranged on the original flue gas conveying pipeline L1 and upstream of the first temperature measuring point P1.

The bypass flue gas pipeline L2 is provided with a second booster fan 13, and the second booster fan 13 is arranged at the downstream of the dust remover 3.

The system further comprises a first conveyor 16 for conveying the activated carbon to be regenerated from the activated carbon outlet at the bottom of the adsorption tower 1 to the activated carbon inlet at the top of the desorption tower 14. The system further comprises a second conveyor 17 for conveying the regenerated activated carbon from the activated carbon outlet at the bottom of the desorption tower 14 to the activated carbon inlet at the top of the adsorption tower 1.

The system also comprises a chimney 9. The adsorption tower 1 is provided with an adsorption tower flue gas outlet 102, and the adsorption tower flue gas outlet 102 is connected to the chimney 9 through an original flue gas conveying pipeline L1.

Example 2

A flue gas purification method for realizing zero discharge of waste water, which uses the system in the embodiment 1, and comprises the following steps:

① temperature control of flue gas of a bypass flue gas pipeline L2, wherein an atomizer 2 is arranged on a bypass flue gas pipeline L2, waste water generated by a washing system 15 is atomized by the atomizer 2 and then mixed with the flue gas in the bypass flue gas pipeline L2, and the waste water exchanges heat with the flue gas entering the bypass flue gas pipeline L2 to form mixed gas of the flue gas and the waste water, the mixed gas of the flue gas and the waste water is dedusted by a deduster 3, and impurities in the mixed gas of the flue gas and the waste water are discharged from a solid outlet 303 of the deduster 3;

③ the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline L2 is merged to the original flue gas conveying pipeline L1, and is mixed with the flue gas in the original flue gas conveying pipeline L1 after the temperature is controlled or adjusted by cold air, and then the mixed gas enters the adsorption tower 1, and the temperature of the flue gas at the inlet of the adsorption tower 1 is adjusted within the range of 100-145 ℃.

Example 3

3) transferring the activated carbon adsorbed with the pollutants from the bottom of the adsorption tower 1 to an analytical tower 14, analyzing and regenerating the activated carbon, discharging the analyzed and regenerated activated carbon from the bottom of the analytical tower 14, and transferring the activated carbon to the adsorption tower 1; the desorbed gas enters a washing system 15, and the washing system 15 washes the desorbed gas and generates wastewater;

① temperature control of flue gas bypassing flue gas duct L2:

the atomizer 2 is arranged on the bypass flue gas pipeline L2, and the waste water generated by the washing system 15 is stored in the waste water storage tank 4. The wastewater in the wastewater tank 4 is alkaline. Wastewater enters the atomizer 2 from the wastewater storage tank 4 along a wastewater input line L3. A waste water pump 5 on the waste water input line L3 powers the waste water into the atomiser 2. Atomized by the atomizer 2 and then mixed with the flue gas in the bypass flue gas pipeline L2, and the waste water exchanges heat with the flue gas entering the bypass flue gas pipeline L2 to form mixed gas of the flue gas and the waste water; the mixed gas of the flue gas and the waste water is dedusted by the deduster 3, and impurities in the mixed gas of the flue gas and the waste water are discharged from a solid outlet 303 of the deduster 3;

② temperature control of flue gas in the original flue gas conveying pipeline L1, namely, introducing cold air into the original flue gas conveying pipeline L1 through an air pipeline L4 to regulate the temperature of the flue gas in the original flue gas conveying pipeline L1 at the downstream of the position of the bypass flue gas pipeline L2 separated from the original flue gas conveying pipeline L1;

In the step 1), a first temperature measuring point P1 is arranged upstream of the position of the bypass flue gas pipeline L2 branched from the original flue gas conveying pipeline L1. A second temperature measurement point P2 is provided between the point at which the raw flue gas duct L1 is fed with cold air and the point at which the bypass flue gas duct L2 merges into the raw flue gas duct L1. A third temperature measuring point P3 is provided on the bypass flue gas duct L2 and downstream of the precipitator 3. A fourth temperature measuring point P4 is provided on the raw flue gas duct L1 downstream of the point where the bypass flue gas duct L2 merges into the raw flue gas duct L1. The first temperature measuring point P1 detects the flue gas temperature T1 in the flue at the corresponding position on line. The second temperature measuring point P2 detects the flue gas temperature T2 in the flue at the corresponding position on line. The third temperature measuring point P3 detects the flue gas temperature T3 in the flue at the corresponding position on line. The fourth temperature measuring point P4 detects the flue gas temperature T4 in the flue at the corresponding position on line. Wherein the target or set temperature value at the fourth temperature measurement point P4 is T4_{Is provided with}＝130℃。

According to the heat Q released by the flue gas entering the bypass flue gas pipeline L2_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct L2_{Water (W)}And equalising, calculating and adjusting the amount of flue gas entering the bypass flue gas duct L2 in sub-step ①, further dependent on the heat Q released by the flue gas entering the adsorption tower 1 through the raw flue gas duct L1_{Cigarette 2}Heat Q absorbed by cold air introduced into the raw flue gas duct L1_{Qi (Qi)}And (3) equally calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline L1 in the substep ②, adjusting the amount of flue gas entering the bypass flue gas pipeline L2 and introducing the flue gas into the bypass flue gas pipeline L1The amount of cold air in the original flue gas conveying pipeline L1 is adjusted or controlled to be T4 at the temperature T4 of the fourth temperature measuring point P4_{Is provided with}Range ± t ℃, wherein t ℃ ═ 3 ℃.

The method comprises the following steps of 1) detecting the content of sulfur oxides in the raw flue gas, and calculating the amount of wastewater generated by a washing system according to the content of the sulfur oxides in the raw flue gas, wherein the method specifically comprises the following steps:

the total amount of the smoke measured by the flowmeter at the upstream of the first temperature measuring point is M₀＝900000Nm³H, detecting SO in the original flue gas₂In a concentration of

Thus, the amount of wastewater M generated by the washing system_{Water (W)}Comprises the following steps:

the heat Q released according to the flue gas entering the bypass flue gas pipeline L2_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct L2_{Water (W)}And (3) equally, calculating and adjusting the amount of the flue gas entering the bypass flue gas pipeline L2 in the substep ①, specifically:

the first temperature measuring point P1 detects that the temperature of the original flue gas is T1-160 ℃, and the temperature of the mixed gas of the flue gas and the waste water at the third temperature measuring point P3 is set to be T3_{Is provided with}Wherein: t3_{Is provided with}＝120℃；

a) Calculating the heat required by wastewater treatment: the amount of wastewater produced by the washing system 15 is M_{Water (W)}3T/h, the initial temperature of the detected waste water is T_{Water (W)}60 ℃, whereby the heat Q to be absorbed is required for treating the waste water produced by the washing system 15_{Water (W)}Comprises the following steps:

In the formula (1), r_{Water (W)}Is the heat of vaporization of the waste water, r_{Water (W)}＝2358.0kJ/kg；C_{Water vapour}Is the ratio of water to vaporHeat capacity, C_{Water vapour}＝1.890kJ/(kg·℃)；

C in formula (2)_{Cigarette with heating means}Is the specific heat capacity of the flue gas, C_{Cigarette with heating means}＝1.014kJ/(kg·℃)；

Obtaining the following components:

M₁＝M_{water (W)}(r_{Water (W)}+C_{Water vapour}(T3_{Is provided with}-T_{Water (W)}))/(C_{Cigarette with heating means}(T1-T3_{Is provided with}))＝135000Nm³/h (4)；

The heat Q released further according to the flue gas entering the adsorption tower 1 through the raw flue gas conveying pipeline L1_{Cigarette 2}Heat Q absorbed by cold air introduced into the raw flue gas duct L1_{Qi (Qi)}And (3) equally, calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline L1 in the substep ②, specifically:

the flow meter 7 upstream of the first temperature measurement point P1 measures the total amount of flue gas as M₀＝900000Nm³The first temperature measuring point P1 detects that the temperature of the original smoke is T1-160 ℃, and the temperature of the mixed gas of the smoke and the cold air at the position of the second temperature measuring point P2 is set as T2_{Is provided with}Wherein: t2_{Is provided with}＝132℃；

a) Computing originalThe heat required to be released by the raw flue gas in the flue gas conveying pipeline L1: the amount of the flue gas introduced into the adsorption tower 1 through the raw flue gas transfer duct L1 is (M)₀-M₁) The heat Q released by the flue gas entering the adsorption tower 1 through the raw flue gas duct L1_{Cigarette 2}Comprises the following steps:

b) The amount of cold air introduced into the original flue gas conveying pipeline L1 is calculated: the quantity of cold air introduced into the original flue gas conveying pipeline L1 is set as M_{Qi (Qi)}Measuring the initial temperature of the cold air as T_{Qi (Qi)}At 20 ℃, the heat Q absorbed by the cold air passing into the raw flue gas duct L1 is thus reduced_{Qi (Qi)}Comprises the following steps:

C in formula (6)_{Qi (Qi)}Specific heat capacity of cold air, C_{Qi (Qi)}＝1.005kJ/(kg·℃)；

Obtaining the following components:

M_{qi (Qi)}＝C_{Cigarette with heating means}(M₀-M₁)(T1-T2_{Is provided with})/(C_{Qi (Qi)}(T2_{Is provided with}-T_{Qi (Qi)}))＝196000Nm³/h (8)；

The temperature T4 of the fourth temperature measuring point P4 is adjusted or regulated by adjusting the amount of the flue gas entering the bypass flue gas pipeline L2 and the amount of the cold air introduced into the original flue gas conveying pipeline L1Control is at T4_{Is provided with}The range of +/-3 ℃ is as follows:

the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline L2 is mixed with the mixed gas of the flue gas and the cold air in the original flue gas conveying pipeline L1 after the temperature is controlled or adjusted by the cold air, the two paths of gases exchange heat, and the heat Q absorbed by the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline L2_{Smoke and water}Heat Q released from the mixed gas of the flue gas and the cold air in the raw flue gas conveying pipeline L1_{Smoke and gas}Equal, i.e.:

Q_{smoke and water}＝Q_{Smoke and gas}(9)，

C in formula (10)₁Is the specific heat capacity of the mixed gas of the flue gas and the waste water, C₁＝1.009kJ/(kg·℃)；C₂Is the specific heat capacity of the mixed gas of the flue gas and the cold air, C₂＝1.011kJ/(kg·℃)。

And detecting the flue gas temperature T2 in the flue at the corresponding position on line according to a second temperature measuring point P2. If T2 equals T2_{Is provided with}Continuing to operate; t2 not equal to T2_{Is provided with}The quantity of cold air introduced into the original flue gas duct L1 is adjusted so that T2 equals T2_{Is provided with}。

Example 4

Example 3 is repeated, except that the third temperature measurement point P3 is setTemperature T3 of mixed gas of flue gas and waste water_{Is provided with}The temperature T2 of the mixed gas of the smoke and the cold air at the position of the second temperature measuring point P2_{Is provided with}Equal and equal to the target or set temperature value T4 at the location of the fourth temperature measurement point P4_{Is provided with}I.e. T2_{Is provided with}＝T3_{Is provided with}＝T4_{Is provided with}＝130℃。

Claims

1. A flue gas purification method for realizing zero discharge of waste water comprises the following steps:

1) a bypass flue gas pipeline (L2) is divided from a raw flue gas conveying pipeline (L1) for conveying high-temperature flue gas to the activated carbon adsorption tower (1), and the raw flue gas enters the adsorption tower (1) through the raw flue gas conveying pipeline (L1) and the bypass flue gas pipeline (L2);

2) the flue gas enters an activated carbon adsorption tower (1), is adsorbed and purified by activated carbon in the adsorption tower (1) and then is discharged, and the activated carbon adsorbing pollutants in the flue gas is discharged from the bottom of the adsorption tower (1);

3) transferring the active carbon adsorbed with the pollutants into an absorption tower (14) from the bottom of the absorption tower (1), allowing the active carbon adsorbed with the pollutants to be absorbed and regenerated, discharging the absorbed and regenerated active carbon from the bottom of the absorption tower (14), and transferring the active carbon into the absorption tower (1); the desorbed gas enters a washing system (15), and the washing system (15) washes the desorbed gas and generates wastewater;

① temperature control of the flue gas of the bypass flue gas pipeline (L2), wherein an atomizer (2) is arranged on the bypass flue gas pipeline (L2), the waste water generated by the washing system (15) is atomized by the atomizer (2) and then mixed with the flue gas in the bypass flue gas pipeline, the waste water exchanges heat with the flue gas entering the bypass flue gas pipeline (L2) to form mixed gas of the flue gas and the waste water, and the heat Q released by the flue gas entering the bypass flue gas pipeline (L2) is used as the basis_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct (L2)_{Water (W)}Equalising, calculating and adjusting the amount of flue gas entering the bypass flue gas duct (L2) in sub-step ①;

② flue gas control of original flue gas conveying pipeline (L1)Temperature: introducing cold air into the raw flue gas conveying pipeline (L1) at the downstream of the position of the bypass flue gas pipeline (L2) separated from the raw flue gas conveying pipeline (L1) to adjust the temperature of the flue gas in the raw flue gas conveying pipeline (L1); according to the heat Q released by the flue gas entering the adsorption tower (1) through the raw flue gas conveying pipeline (L1)_{Cigarette 2}The heat Q absorbed by the cold air introduced into the raw flue gas duct (L1)_{Qi (Qi)}And (3) equaling, calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline (L1) in the substep ②;

③ mixed gas of flue gas and waste water in a bypass flue gas pipeline (L2) is merged into an original flue gas conveying pipeline (L1) and is mixed with the flue gas subjected to temperature control or temperature regulation through cold air in an original flue gas conveying pipeline (L1) to enter an adsorption tower (1), the temperature of the flue gas at the inlet of the adsorption tower (1) is regulated within a specified range, a fourth temperature measuring point (P4) is arranged on the original flue gas conveying pipeline (L1) and at the downstream of the position where a bypass flue gas pipeline (L2) is merged into an original flue gas conveying pipeline (L1), the fourth temperature measuring point (P4) detects the flue gas temperature T4 in a flue at a corresponding position on line, wherein the target temperature value or set value of the fourth temperature measuring point (P4) is T4_{Is provided with}(ii) a The temperature T4 of the fourth temperature measuring point (P4) is adjusted or controlled at T4 by adjusting the amount of the smoke entering the bypass smoke pipeline (L2) and the amount of the cold air passing into the raw smoke conveying pipeline (L1)_{Is provided with}A temperature range of + -t deg.C, wherein t deg.C is in the range of 1-5 deg.C.

2. The method of claim 1, wherein: in the step 1), a first temperature measuring point (P1) is arranged at the upstream of the position of a bypass flue gas pipeline (L2) separated from an original flue gas conveying pipeline (L1); a second temperature measuring point (P2) is arranged between the position of the cold air introduced into the raw flue gas conveying pipeline (L1) and the position of the bypass flue gas pipeline (L2) merged to the raw flue gas conveying pipeline (L1); a third temperature measurement point (P3) is arranged on the bypass flue gas pipeline (L2) and is positioned at the downstream of the dust remover (3); the first temperature measuring point (P1) detects the flue gas temperature T1 in the flue at the corresponding position on line, the second temperature measuring point (P2) detects the flue gas temperature T2 in the flue at the corresponding position on line, and the third temperature measuring point (P3) detects the flue gas temperature T3 in the flue at the corresponding position on line.

3. The method of claim 1, wherein: the target or set temperature value at the fourth temperature measurement point (P4) is T4_{Is provided with}，T4_{Is provided with}Taking the value within the range of 100-145 ℃; namely, the temperature of the flue gas at the inlet of the adsorption tower (1) is regulated within a specified range.

4. The method of claim 3, wherein: t4_{Is provided with}The temperature is within the range of 110 ℃ and 140 ℃.

5. The method according to claim 1, wherein in the substep ②, the mixed gas of flue gas and waste water is dedusted by a deduster (3), and impurities in the mixed gas of flue gas and waste water are discharged from a solids outlet (303) of the deduster (3).

6. The method according to any one of claims 2-5, wherein: the step 1) also comprises the steps of detecting the content of sulfur oxides in the raw flue gas, and calculating the amount of wastewater generated by the washing system (15) according to the content of the sulfur oxides in the raw flue gas, wherein the steps are as follows:

the total amount of the smoke measured by the flowmeter (7) at the upstream of the first temperature measuring point (P1) is M₀Detecting SO in the original flue gas₂In a concentration of

Thereby, the amount M of waste water produced by the washing system (15)_{Water (W)}Comprises the following steps:

Unit mg/Nm³；k₁Is a constant, and has a value of 0.9 to 1.6.

7. The method according to any of claims 1 to 5, characterized in that in step 3) the waste water produced by the scrubbing system (15) is stored in a waste water storage tank (4), the waste water is fed from the waste water storage tank (4) along a waste water feed line (L3) into the atomizer (2), and in sub-step ② the cold air is fed from an air line (L4) to a raw flue gas feed line (L1).

8. The method according to claim 6, characterized in that in step 3), the waste water produced by the scrubbing system (15) is stored in a waste water storage tank (4), the waste water is fed from the waste water storage tank (4) along a waste water feed line (L3) to the atomizer (2), and in a sub-step ②, the cold air is fed from an air line (L4) to a raw flue gas feed line (L1).

9. The method of claim 7, wherein: the wastewater in the wastewater storage tank (4) is neutral or alkaline; and a wastewater pump (5) is arranged on the wastewater input pipeline (L3), and the wastewater pump (5) provides power for wastewater to enter the atomizer (2).

10. The method of claim 8, wherein: the wastewater in the wastewater storage tank (4) is neutral or alkaline; and a wastewater pump (5) is arranged on the wastewater input pipeline (L3), and the wastewater pump (5) provides power for wastewater to enter the atomizer (2).

11. The method according to any one of claims 1-5, wherein: the heat Q released according to the flue gas entering the bypass flue gas duct (L2)_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct (L2)_{Water (W)}And (3) equally, calculating and adjusting the amount of flue gas entering the bypass flue gas duct (L2) in the substep ①, specifically:

the first temperature measuring point (P1) detects the temperature of the original flue gas as T1, and the temperature of the mixed gas of the flue gas and the waste water at the position of the third temperature measuring point (P3) is set as T3_{Is provided with}Wherein: t3_{Is provided with}Is taken within the range of 100 ℃ and 160 ℃;

a) calculating the heat required by wastewater treatment: washing system (15) generatingThe amount of waste water of (A) is M_{Water (W)}Detecting the initial temperature of the wastewater as T_{Water (W)}Whereby the heat Q to be absorbed is required for treating the waste water produced by the washing system (15)_{Water (W)}Comprises the following steps:

b) calculating the required flue gas amount of the bypass flue gas pipeline (L2): setting the amount of flue gas entering the bypass flue gas pipeline (L2) as M₁Whereby the heat Q released by the flue gas entering the bypass flue gas duct (L2)_{Cigarette 1}Comprises the following steps:

heat Q released by the flue gas entering the bypass flue gas duct (L2)_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct (L2)_{Water (W)}Equality, we can get:

Obtaining the following components:

The opening degree of a bypass valve (6) on the bypass flue gas pipeline (L2) is adjusted so that the amount of the flue gas entering the bypass flue gas pipeline (L2) is M₁。

12. The method of claim 6, wherein: said release being dependent on the flue gas entering the bypass flue gas duct (L2)Heat quantity Q of discharge_{Cigarette 1}With the heat Q absorbed by the waste water sprayed into the bypass flue gas duct (L2)_{Water (W)}And (3) equally, calculating and adjusting the amount of flue gas entering the bypass flue gas duct (L2) in the substep ①, specifically:

a) calculating the heat required by wastewater treatment: the amount of waste water produced by the washing system (15) is M_{Water (W)}Detecting the initial temperature of the wastewater as T_{Water (W)}Whereby the heat Q to be absorbed is required for treating the waste water produced by the washing system (15)_{Water (W)}Comprises the following steps:

Obtaining the following components:

13. The method of claim 11, wherein: t3_{Is provided with}Is taken within the range of 110 ℃ and 140 ℃.

14. The method of claim 12, wherein: t3_{Is provided with}Is taken within the range of 110 ℃ and 140 ℃.

15. The method of claim 11, wherein: further according to the heat Q released by the flue gas entering the adsorption tower (1) through the raw flue gas conveying pipeline (L1)_{Cigarette 2}The heat Q absorbed by the cold air introduced into the raw flue gas duct (L1)_{Qi (Qi)}And (3) equally, calculating and adjusting the amount of cold air introduced into the original flue gas conveying pipeline (L1) in the substep ②, specifically:

the total amount of the smoke measured by the flowmeter (7) at the upstream of the first temperature measuring point (P1) is M₀The temperature of the original smoke detected by the first temperature measuring point (P1) is T1, and the temperature of the mixed gas of the smoke and the cold air at the position of the second temperature measuring point (P2) is set to be T2_{Is provided with}Wherein: t2_{Is provided with}Is taken within the range of 100 ℃ and 160 ℃;

a) calculating the required heat released by the raw flue gas in the raw flue gas conveying pipeline (L1): the quantity of flue gas entering the adsorption column (1) through the raw flue gas duct (L1) is (M)₀-M₁) The heat Q released by the flue gas entering the adsorption tower (1) through the raw flue gas conveying pipeline (L1)_{Cigarette 2}Comprises the following steps:

b) Calculating the introduced original flue gas conveying pipeline (L1)) Amount of cold air of (c): setting the quantity of cold air introduced into the original flue gas conveying pipeline (L1) as M_{Qi (Qi)}Measuring the initial temperature of the cold air as T_{Qi (Qi)}Thereby, the heat Q absorbed by the cold air introduced into the raw flue gas delivery duct (L1)_{Qi (Qi)}Comprises the following steps:

C in formula (6)_{Qi (Qi)}Is the specific heat capacity of the cold air;

heat Q released by the flue gas entering the adsorption column (1) through the raw flue gas duct (L1)_{Cigarette 2}The heat Q absorbed by the cold air introduced into the raw flue gas duct (L1)_{Qi (Qi)}Equality, we can get:

Obtaining the following components:

The opening degree of a cold air valve (8) on the air pipeline (L4) is adjusted, so that the quantity of cold air introduced into the original flue gas conveying pipeline (L1) is M_{Qi (Qi)}。

16. The method of claim 15, wherein: t2_{Is provided with}Is taken within the range of 110 ℃ and 140 ℃.

17. The method of claim 15, wherein: the temperature T4 of the fourth temperature measuring point (P4) is adjusted or controlled at T4 by adjusting the amount of the smoke entering the bypass smoke pipeline (L2) and the amount of the cold air introduced into the raw smoke conveying pipeline (L1)_{Is provided with}The range of +/-t ℃ is as follows:

the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline (L2) and the original flue gas conveying pipeline (L1) are subjected to temperature control or regulation by cold airThe mixed gas of the warmed flue gas and the cold air is mixed, after the two paths of gas exchange heat, the temperature T4 of a fourth temperature measuring point (P4) is regulated or controlled at T4_{Is provided with}The range of +/-t ℃; the heat Q absorbed (or released) by the mixed gas of the flue gas and the waste water in the bypass flue gas pipeline (L2)_{Smoke and water}Heat Q released (or absorbed) by the mixed gas of the flue gas and the cold air in the raw flue gas conveying pipeline (L1)_{Smoke and gas}Equal, i.e.:

Q_{smoke and water}＝Q_{Smoke and gas}(9)，

18. The method of claim 17, wherein: t2_{Is provided with}＝T3_{Is provided with}＝T4_{Is provided with}(ii) a Detecting the flue gas temperature T2 in the flue at the corresponding position on line according to a second temperature measuring point (P2); if T2 equals T2_{Is provided with}Continuing to operate; t2 not equal to T2_{Is provided with}Adjusting the quantity of cold air introduced into the raw flue gas duct (L1) so that T2 equals T2_{Is provided with}；

Detecting the flue gas temperature T3 in the flue at the corresponding position on line according to a third temperature measuring point (P3); if T3 equals T3_{Is provided with}Continuing to operate; t3 not equal to T3_{Is provided with}Adjusting the amount of flue gas entering the bypass flue gas duct (L2) such that T3 equals T3_{Is provided with}；

Detecting the flue gas temperature T4 in the flue at the corresponding position on line according to a fourth temperature measuring point (P4); if T4 equals T4_{Is provided with}Continuing to operate; t4 not equal to T4_{Is provided with}Adjusting the amount of cold air passing into the original flue gas conveying pipe (L1) and the amount of flue gas entering the bypass flue gas pipe (L2) so that T4 is equal to T4_{Is provided with}。

19. The method according to any one of claims 1-5, wherein: in the step 2), the flue gas absorbed and purified by the activated carbon in the absorption tower (1) is discharged through a chimney (9).

20. The method of claim 6, wherein: in the step 2), the flue gas absorbed and purified by the activated carbon in the absorption tower (1) is discharged through a chimney (9).