CN105920967A - Ultralow-emission, water-saving and smoke suppression synergistic advanced purification system and method thereof - Google Patents

Abstract

The invention provides an ultra-low emission, water-saving and smoke-eliminating cooperative deep purification system and method, which are used for further processing outlet flue gas to meet the requirements of ultra-low emission, smoke elimination and water-saving cooperative deep purification. The system mainly includes a micro-cooled phase-change accelerator, a multi-pollutant trap and a micro-heat smoke eliminator arranged in sequence in the outlet flue of the desulfurization tower. The flue gas from the desulfurization tower passes through the micro-cooled phase-change accelerator, After being treated by the multi-pollutant trap and the micro-heat smoke eliminator, it is discharged through the chimney. Compared with the existing conventional method of directly heating up the flue gas to slow down the white smoke from the chimney, directly raising the temperature of the saturated or supersaturated flue gas containing a large amount of water vapor to the unsaturated state requires more energy consumption. The smoke elimination method of the present invention The smoke elimination in the collaborative purification system adopts the method of micro-cooling and then micro-rising, which not only promotes the removal of fine particles, mist droplets, soluble salts and other pollutants, but also recovers the water in the flue gas, and has obvious advantages in energy saving and consumption reduction. At the same time, real smoke elimination is realized.

Description

Ultra-low emission water saving and smoke elimination collaborative purification system and method

Technical field:

The invention provides an ultra-low emission water-saving and smoke-eliminating collaborative purification system and method, belonging to the field of resource and environment flue gas purification.

Background technique:

With the control of air pollutants in thermal power plants entering the ultra-low emission stage, the emission concentrations of NOx, SO ₂ , dust and other pollutants in the flue gas emissions of thermal power plants are required to be controlled at 50 mg/m ³ , 35 mg/m ³ , and 10 mg/m 3 , respectively. m ³ or less, even some areas (such as Shanghai, Zhejiang, etc.) require control measures to eliminate the phenomenon of gypsum rain and colored smoke rain in the chimney after desulfurization, so as to avoid white smoke.

At present, ultra-low NOx emissions can be achieved through low-nitrogen combustion + high-efficiency SCR technology, and ultra-low emissions of SO ₂ can be achieved through single/double-tower double-cycle technologies, but ultra-low emissions of smoke and dust have always plagued coal-fired power stations and related industrial boilers , by adding wet electrostatic precipitator, ultra-low emission of smoke and dust can be achieved, but the investment and operation and maintenance costs are high, and the reliability and stability of the system operation need to be further tested by time. Therefore, there is a potential market demand for a technology that does not use wet electrostatic precipitator to achieve ultra-low emission of smoke and dust and can eliminate gypsum rain and white smoke at the same time.

For the elimination of gypsum rain and white smoke, the current conventional method is to directly reheat the flue gas. This measure has high energy consumption and will greatly increase the coal consumption of power generation. production safety hazards.

Therefore, it is particularly important to develop a multi-functional ultra-low emission water-saving and smoke-eliminating collaborative purification method, technology and equipment that are suitable for the development needs of the country, meet the ultra-low emission control requirements, and can eliminate gypsum rain and colored plume of tail flue gas.

Invention content:

The invention provides a multi-functional ultra-low emission water-saving and smoke-eliminating collaborative purification system, which is used for further processing outlet flue gas, deep purification and emission reduction of multi-pollutants, so as to meet the requirements of low-emission chimney smoke elimination.

Another object of the present invention is to provide a collaborative purification method for ultra-low emission of flue gas, saving water and eliminating smoke.

The concrete technical scheme that the present invention adopts is as follows:

A multi-functional ultra-low emission water-saving and smoke elimination collaborative purification system, which mainly includes a micro-cooled phase change accelerator, a multi-pollutant trap and a micro-heat smoke eliminator arranged in sequence in the outlet flue of the desulfurization tower. The flue gas is discharged through the chimney after being treated by the micro-cooled phase change accelerator, the multi-pollutant trap and the micro-heat smoke eliminator in sequence; the distance between the micro-cooled phase-change accelerator and the multi-pollutant trap is 5 ~15 m; the distance between the multi-pollutant trap and the micro heat smoke eliminator is 5~25m.

A further design of the present invention is:

The system is equipped with a flushing system, including pumps, flushing pipelines and nozzles, which are used to clean the micro-cooled phase change accelerator, multi-pollutant trap and micro-heat smoke eliminator.

The system is also equipped with a drainage system, including drainage tanks on both sides of the multi-pollutant trap. The drainage tanks are connected with the inside of the desulfurization tower or the slurry preparation system, or connected with the filter cake flushing water system of the desulfurization gypsum dehydration belt machine, or lead The ash and slag removal system is mixed with slag water for co-treatment.

The micro-cooling phase change accelerator and the micro-heating smoke eliminator are similar in structure, mainly composed of a shell, an inlet medium flow pipe, an isolation shut-off valve, an inlet distribution box, and a heat exchange tube passing through the flue perpendicular to the flue gas flow direction. The inlet distribution box and the outlet confluence box are symmetrically arranged and divided into several small chambers. Each group of inlet and outlet chambers is connected to a set of heat exchange pipelines and corresponding The inlet and outlet medium flow pipes and isolation shut-off valves are used to realize the independent control function of the partitions; the side wall of the flue gas of each group of inlet and outlet chambers is a honeycomb orifice plate, and each opening is connected to the corresponding heat exchange pipeline; the shell is composed of The metal plate is connected with the inlet distribution box and the outlet combiner box to form a sealed frame, or connected with the flue through welding or flanges.

The method for collaborative purification of ultra-low emission and smoke elimination of flue gas according to the present invention includes the following processing steps:

_First , the temperature of the flue gas at T1 at the outlet of the desulfurization tower is lowered to T2 (0.1-10°C) through the micro _- cooling phase change accelerator. , the fine particles are condensed and agglomerated, and the flue gas is condensed, demisted, and dusted through the heat exchange pipeline or heat exchanger of the micro-cooled phase change polymerizer, and part of the water is removed. After the treatment, the flue gas enters the multi-pollutant trap Collector;

Second, through the multi-pollutant trap to further capture most of the remaining mist and particulate matter in the flue gas, most of the condensed water will be removed, and the treated flue gas will be sent to the micro-heat smoke eliminator;

Third, the micro-heat smoke eliminator raises the temperature of the flue gas to T ₃ (0.1-10°C) to become unsaturated flue gas, which is discharged through the chimney;

where T2 is calculated by the following _formula :

T ₂ =44.29ηe ^0.065T1 /H ₁ -T ₁ (1)

Where T3 is calculated by the following _formula :

T ₃ =46.5045δe ^0.065T2 /H ₀ -T ₂ (2)

In the formula, T1 is the actual temperature of the flue gas at the outlet _of the desulfurization tower, T2 is the flue gas temperature that should be controlled at the outlet _of the micro _- cooling phase change polymerizer, T3 is the temperature of the flue gas that should be controlled after being heated by the micro-heating smoke eliminator, H ₀ is the ambient air humidity, H ₁ is the flue gas humidity at the outlet of the desulfurization tower, η is the cooling economic cooling coefficient, the value range is 0.05-1, and δ is the micro thermal economic coefficient, the value range is 0-0.75.

The method also includes the following process: the flushing system regularly flushes the surface of the micro-cooled phase change accelerator, the multi-pollutant trap and the micro-heat smoke eliminator, and after the flushing water and the condensed water in the flue are recovered, the The drainage system is returned to the absorption tower or sent to the slurry preparation system, or replaces part of the water in the desulfurization system to reduce the water consumption of the desulfurization system.

The heat exchange pipeline of the micro-cooling phase change accelerator and the micro-heating smoke eliminator adopts fluoroplastic or metal heat pipes with good thermal conductivity, corrosion resistance and wear resistance, or mature large surface area heat exchangers can also be used. The cooling heat exchange medium of the micro-cooling phase change accelerator is generally the pretreated industrial water of the power plant, and the heating medium of the micro-heat smoke eliminator is generally hot water or other heat exchange media from the waste heat recovery system of the power plant.

The multi-pollutant deep purification and water-saving working principle of the micro-cooled phase change accelerator of the present invention:

The micro-cooled phase change accelerator in the system of the present invention has the functions of cooling condensation and phase change condensation. Water vapor can condense into countless fine mist droplets with super specific surface, which can promote the dissolution and absorption of soluble acid gas (such as HCl, HF, SO ₂ , SO ₃ , NO ₂ , etc.), and is also conducive to wetting SO ₃ aerosol and ultrafine particles Such as PM _2.5 precursor pollutants that are difficult to remove, change the physical and chemical properties of the surface, facilitate their collision and aggregation into mist droplets, gradually grow into water droplets, wash, condense, and separate out gas, liquid, and solid pollution from the flue gas substances, including carried soluble salt ions, to achieve deep purification and emission reduction of pollutants. At the same time, it has the function of cooling and heat exchange, especially at the moment of phase change, the slight sudden change of heat will promote the thermal condensation of particles, and produce a large number of ultra-fine droplets, which strengthens the wetting and humidification of fine particles and aerosol surfaces, Change its characteristics to promote the formation of fine particles and ultra-fine droplets of ultra-fine condensation nuclei. Fine particles and ultra-fine mist droplets are further thermally condensed and reunited to gradually form large particles and large mist droplets that are easy to capture, which can realize dust removal and dehumidification of flue gas; saturated water vapor and carried mist droplets will condense under the condition of temperature drop A large amount of water is precipitated, which can save water in the desulfurization system by recycling it and returning it to the desulfurization system for reuse.

The water-saving and smoke-eliminating process diagram of the present invention is as follows:

Fig. 2 shows that the method diagram of eliminating white smoke that the present invention carries out in conjunction with flue gas moisture content curve, curve in the figure is flue gas temperature-humidity saturation curve, when discharging flue gas reaches chimney outlet, under corresponding ambient temperature, When the water vapor partial pressure data point is above the saturated humidity line curve, it is saturated or supersaturated wet flue gas, and white smoke will be produced when discharged. The principle of eliminating white smoke is to remove the moisture in saturated or supersaturated flue gas, and when the flue gas is discharged to the environment, it will still be unsaturated flue gas, that is, no white smoke will be produced. The extracted water can be reused in desulfurization, ash and slag systems to replace process water, thereby reducing water consumption in other systems.

In the figure, the flue gas at the outlet of the desulfurization tower is supersaturated wet flue gas with a large amount of mist droplets at around 40-60°C (that is, point A, the curve corresponds to saturation, the supersaturated area is on the curve, and the unsaturated area is below the curve), which is directly discharged After the temperature drops to the ambient temperature (point D in the figure), white smoke will be generated. That is, if no measures are taken, white smoke will be generated as long as the straight line AD crosses the saturation line. However, in the present invention, the flue gas state is lowered from A to point B (line AB in the figure) by cooling the temperature of the micro-cooled phase change accelerator first, and a large amount of water droplets, mist droplets and fine particles will be condensed and separated out, and after multi-pollutant capture After dust removal and mist removal by the collector, the temperature is raised to point C through the micro-heat smoke eliminator and then discharged. The process of BC line makes the saturated flue gas become unsaturated flue gas, and condenses water vapor. During the discharge process, the change process of the flue gas is the CD line, and the flue gas in the CD process is in an unsaturated state, that is, the CD and the saturated humidity curve do not cross, so no white smoke will be generated during discharge.

The existing smoke elimination system directly raises the temperature of saturated or supersaturated flue gas, and the temperature of the flue gas is raised from point A on the left side of the saturated humidity line to a temperature higher than point E on the right side, generally above 75°C, except for supersaturated flue gas In addition to heating to make the partial pressure of water vapor into an unsaturated state, it is also necessary to evaporate a large number of slurry droplets and mist droplets carried in the flue gas. No white smoke can be seen temporarily, but because the temperature difference between the exhaust smoke and the ambient temperature is large, after the rapid mixing with the ambient atmosphere, the water vapor partial pressure quickly returns to the supersaturated area, so there will be high-temperature flue gas discharged from the chimney for a certain distance (about 0.5 to 2m) White smoke is also produced, especially in areas with high ambient humidity. Moreover, this method requires several times more energy consumption than the method of the present invention. According to experimental research, the energy consumption is 1-3 times higher than that of the present application; the smoke elimination in the smoke elimination collaborative purification system of the present invention is to slightly cool down and dehydrate from A to B. , and then slightly increase the temperature from point B, which has obvious energy-saving advantages, and at the same time realizes the real elimination of smoke plume.

Compared with the prior art, the present invention has the following advantages:

In the present invention, the phase change coagulator is used to economically lower the temperature of the flue gas ⊿T _drop =T ₂ -T ₁ ℃, so that the saturated and supersaturated water vapor in the flue gas condenses and precipitates, and at the same time, the fine mist droplets and fine particles in the flue gas generate The phase change coagulation grows and condenses, and the precipitated water droplets collide with the tube wall and are captured to achieve the purpose of dust removal and mist removal.

In the present invention, the multi-pollutant trap is used for further purification of the flue gas. After the water vapor in the flue of the phase change condenser is cooled by T ₂ -T ₁ , a large number of mist droplets are condensed and gradually grow up, and at the same time, they are gradually infiltrated in the flue gas. Phase change condenses the fine particles that have been agglomerated, but only part of them is intercepted by the phase change cooling agglomerator, adding a multi-pollutant trap helps to further remove the other part of mist and particles.

In the present invention, the micro-heat smoke eliminator is used to increase the temperature of the flue gas after passing through the previous two facilities ⊿T _rise =T ₃ -T ₂ ℃, the purpose is to change the dehydrated and dust-removed flue gas from saturated wet flue gas to For unsaturated wet flue gas, the specific heating temperature needs to be determined in combination with the ambient temperature and local atmospheric pressure. The flue gas can be turned into dry flue gas by slight heat, and the white smoke can be eliminated by discharging the chimney.

The flushing and water-repellent system in the present invention regularly flushes the three facilities, the nozzles are arranged to cover the cross-section of the facilities, the flushing method adopts gap operation, and pressure gauges are installed before and after each facility to monitor the change of resistance. Drainage tanks are set on both sides of the multi-pollutant trap to recover the condensed water and flushing water in the flue and return them to the absorption tower or slurry preparation system.

Description of drawings:

Fig. 1 is a diagram of the ultra-low emission water-saving and smoke-eliminating collaborative purification system of the present invention.

Fig. 2 is a schematic diagram of a method for eliminating white smoke combined with flue gas humidity curves.

Fig. 3 is a structural diagram of a micro-cooling phase change accelerator and a micro-heating smoke eliminator.

In the figure: 1-micro-cooling phase change accelerator; 2-multi-pollutant trap; 3-micro-heat smoke eliminator; 4-drain tank; 5-desulfurization tower. 11-Shell; 12-Medium flow pipeline; 13-Isolation shut-off valve; 14-Inlet distribution box; 15-Exit confluence box; 16-Heat exchange pipeline; 17-Inlet chamber; - flue.

detailed description:

Below in conjunction with accompanying drawing, the present invention will be further described:

Embodiment one:

As shown in Figure 1, the multi-functional ultra-low emission water-saving and smoke-eliminating collaborative purification system of the present invention mainly includes four parts, which are the micro-cooled phase change accelerator 1, the multi-pollutant Trap 2, micro heat smoke eliminator 3 and corresponding flushing and drainage system. The distance between the micro-cooling phase change accelerator and the multi-pollutant trap is set to 10 m; the distance between the multi-pollutant trap and the micro-heat smoke eliminator is 10 m.

According to the positional relationship of each part, the flue gas at the outlet of the desulfurization tower 5 is sequentially treated by the slightly cold phase change accelerator 1, the multi-pollutant trap 2 and the flue gas slightly heat smoke eliminator 3, and then discharged through the chimney.

The flushing system includes pumps, flushing pipelines and nozzles, which are used to clean the micro-cooled phase change accelerator, multi-pollutant trap and flue gas micro-heat smoke eliminator.

The drainage system adopts the structural form of drainage grooves on both sides of the multi-pollutant trap, and the drainage groove 4 is connected with the deflow tower or the slurry preparation system.

Embodiment two:

On the basis of Embodiment 1, the structure of the micro-cooling phase change accelerator and the micro-heating smoke eliminator in the system of the present invention are similar, and they are arranged in the flue 19, as shown in Figure 3, mainly composed of a housing 11, an inlet medium Flow pipeline 12 and its (inlet) isolation shut-off valve 13, inlet distribution box 14, heat exchange pipeline 16 passing through the flue perpendicular to the flue gas flow, outlet combiner box 15, outlet medium flow pipeline 12 and Its (outlet) isolation shut-off valve is composed of; the inlet distribution box 14 and the outlet confluence box 15 are symmetrically arranged, and are divided into several small chambers, and each group of inlet and outlet chambers is connected to a set of heat exchange pipelines 16, and the corresponding inlet and outlet medium flow Pipelines and isolation shut-off valves to achieve independent control functions in different regions; the flue gas side walls of each group of inlet chambers 17 and outlet chambers 18 are honeycomb orifice plates, and each opening is connected to a corresponding heat exchange pipeline; the shell 11 is composed of The metal plate is connected with the inlet distribution box and the outlet combiner box to form a sealed frame, or connected with the flue through welding or flanges. The heat exchange pipeline is made of fluoroplastic or metal material with good thermal conductivity, temperature resistance, corrosion resistance and wear resistance.

Embodiment three:

The collaborative purification method for ultra-low emission of flue gas and smoke elimination of the present invention adopts the system processing process of Embodiment 2 as follows:

First measure the following data: the actual temperature T ₁ of the flue gas at the outlet of the desulfurization tower, the humidity of the ambient air H ₀ , the humidity of the flue gas at the outlet of the desulfurization tower H ₁ , and determine the cooling economic cooling coefficient η, which ranges from 0.05 to 1 (0.5 in this example), Micro thermal economic coefficient δ, the value range is 0-0.75 (0.35 is taken in this example).

In the following formula: T ₂ is the flue gas temperature that should be controlled at the outlet of the micro-cooling phase change accelerator, and T ₃ is the flue gas temperature that should be controlled after heating by the micro-heating smoke eliminator.

First, the flue gas at T ₁ °C at the outlet of the desulfurization tower is cooled to T ₂ °C by a micro-cooling phase change accelerator for condensation, mist removal, and dust removal. After the treatment, the flue gas enters the multi-pollutant trap;

T ₂ =44.29ηe ^0.065T1 /H ₁ -T ₁ (1)

Second, the remaining mist and particles in the flue gas are further captured by the multi-pollutant trap, and then the flue gas is sent to the micro-heat smoke eliminator;

Third, the micro-heat smoke eliminator heats up the flue gas to T ₃ ℃ to become unsaturated flue gas, which is discharged through the chimney.

T ₃ =46.5045δe ^0.065T2 /H ₀ -T ₂ (2)

Fourth, the flushing system regularly flushes the surface of the micro-cooled phase change accelerator, the multi-pollutant trap and the micro-heated smoke eliminator, and the flushing water and the condensed water in the flue are returned to the absorption tower through the drainage system. Or sent to the slurry preparation system, or used for desulfurization gypsum filter cake washing, instead of process water for desulfurization.

Applications:

A flue gas desulfurization device with a flue gas treatment capacity of 50,000 m ³ /h is equipped with the ultra-low emission water-saving and smoke-eliminating collaborative purification system of the present invention, in which the slightly-cooled phase change accelerator and the slightly-heated smoke eliminator are equipped with There is a heat transfer medium (water) delivery pump, the cooling medium of the micro-cooling phase change polymerizer is open cooling water (no need to calculate the cooling energy consumption, only the power consumption of the delivery pump is counted), and the heating medium of the micro-heat smoke eliminator is external heat Water (calorie is included in energy consumption statistics), the opening control conditions and effects of each facility of the device of the present invention are shown in the four groups of tests shown in Table 1 below:

The situation in Test 2 is similar to the traditional method of directly heating white smoke. It can be seen that the energy consumption of the system of the present invention can save 45.7% of energy consumption compared with the traditional method of directly heating flue gas, and can promote the reduction of multi-pollutant emissions.

Test 4 corresponds to the system and method of the present invention; Test 1 adopts the system of the present invention, the multi-pollutant trap is put into operation, and the slightly cold phase change accelerator and the slightly heat smoke eliminator are not put into operation; Test 2 adopts the system of the present invention , the multi-pollutant trap was put into operation, wherein the micro-cooled phase change polymerizer was out of service, and the micro-heat smoke eliminator was put into operation to raise the temperature; Test 3 adopted the system of the present invention, and the multi-pollutant trap was put into operation, wherein the micro-cooled phase The variable accelerator was put into operation, and the micro-heat smoke eliminator was out of operation. Compared with Experiment 1, the emission of particulate matter in Experiment 4 was reduced by 61.4%, mainly because the main component of particulate matter in the flue gas after desulfurization was gypsum, which was derived from the gypsum slurry droplets carried by the desulfurization flue gas. At the same time, the phase change of water vapor is caused, and a large number of fine gypsum droplets are condensed and precipitated to escape the flue gas. At the same time, some fine particles and SO3 are agglomerated and reduced.

In addition, the precursor pollutants of secondary particles that can be formed in condensed water samples are various ions that can form soluble salts dissolved in slurry or water, including Cl ^- , F ^- , Br ^- , Na ⁺ , Mg ²⁺ , Ca ²⁺ , K ⁺ , etc. are also removed into the liquid phase, which directly reduces the pollutants in the gas phase. Therefore, the input of the micro-cooled phase change accelerator of the present invention and the sampling and analysis of flue gas sudden condensation after the multi-pollutant trap The content of soluble salts carried has decreased significantly. The test results of the soluble salt ions in the condensed water samples of the flue gas after the multi-pollutant trap are shown in Table 2. The test refers to the DL/T997-2006 and GB5750_2006 standards. Equipment: ICS-200, Optim700 DV, etc.

Table 1

Table 2

It can be seen from Table 2 that after the ultra-low emission water-saving and smoke-elimination cooperative purification system of the present invention is opened, the emission of soluble salts in the exhaust flue gas drops significantly, with a drop of 71.58%. The conductivity of the liquid is reduced by 79.21%, which significantly reduces the pollutants in the gas phase and truly achieves low emissions.

Claims (7)

1. a minimum discharge water saving smoke elimination cooperated purification system, it is characterised in that: mainly include that being sequentially arranged in desulfurizing tower goes out Chilly phase transformation in mouth flue promotees poly-device, multi-pollutant catcher and slight fever smoke eliminator, and desulfurizing tower flue gas out sequentially passes through Chilly phase transformation promotees after poly-device, multi-pollutant catcher and slight fever smoke eliminator process through smoke stack emission；Chilly phase transformation promotees poly-device with many Between contaminant trapping device, spacing is 5～15 m；Between multi-pollutant catcher and slight fever smoke eliminator, spacing is 3～25m.

Minimum discharge water saving smoke elimination cooperated purification system the most according to claim 1, it is characterised in that: this system is configured with punching Wash system, including pump, flushing line and nozzle, for chilly phase transformation is promoted poly-device, multi-pollutant catcher and slight fever smoke eliminator It is carried out.

Minimum discharge water saving smoke elimination cooperated purification system the most according to claim 2, it is characterised in that: this system is also configured with Draining system, is included in the drain tank of multi-pollutant catcher both sides, and drain tank is internal with desulfurizing tower or serum producing system connects Logical, or be connected with desulfurated plaster dehydration belt feeder filter cake flushing water system, or be directed toward ash-slag disposal system and mix with pulp water and control altogether.

4. according to claim 1-3 arbitrary described minimum discharge water saving smoke elimination cooperated purification system, it is characterised in that: chilly phase transformation Promote poly-device similar with slight fever smoke eliminator structure, mainly by housing, import medium is through-flow pipeline and isolation shut-off valve, import distribution Case and flue gas flow direction pass perpendicularly through the heat exchanging pipe of flue, outlet header box, the outlet through-flow pipeline of medium and isolation shut-off valve thereof Composition.

Minimum discharge water saving smoke elimination cooperated purification system the most according to claim 4, it is characterised in that: import distributor box and going out Mouth header box is arranged symmetrically with, and is divided into some cells, and often group import and export cell correspondence connects one group of heat exchanging pipe, often organizes import and export Cell fume side wall is honeycomb orifice plate, and each perforate is all corresponding connects corresponding heat exchanging pipe；Housing mainly by metallic plate with Import distributor box and outlet header box connect formation seal frame composition, or are connected with flue by welding or flange.

6. utilizing the flue gas minimum discharge smoke elimination synergistic purification method of claim 1-5 any system, the method includes following place Reason process:

First, desulfurizing tower outlet T₁The flue gas of temperature promotees poly-device through chilly phase transformation and is cooled to T₂Temperature, common in temperature drop and phase transformation Under effect, in cohesion flue gas, mist drips and coagulates with fine particle, and heat exchanging pipe or heat exchanger by the chilly phase transformation poly-device of rush are to flue gas Carry out condensing, except mist, dust removal process, abjection part moisture content, flue gas entrance multi-pollutant catcher after process；

Second, trap most of remaining droplet and particulate matter in flue gas further via multi-pollutant catcher, the biggest portion of abjection Fractional condensation bears water, and the flue gas after process is re-fed into slight fever smoke eliminator；

3rd, flue gas is warming up to T by slight fever smoke eliminator₃Temperature becomes unsaturated flue gas, via smoke stack emission；

The most chilly phase transformation promotees poly-device and exports flue-gas temperature T that should control₂It is calculated by below equation:

T₂=44.29ηe^0.065T1/H₁-T₁ (1)

Flue-gas temperature T that wherein should control after the heating of slight fever smoke eliminator₃It is calculated by below equation:

T₃ =46.5045δe^0.065T2/H₀-T₂ (2)

In formula, T₁For desulfurizing tower exiting flue gas actual temperature, H₀For ambient air humidity, H₁For desulfurizing tower exiting flue gas humidity, η For cooling down economic coefficient of temperature drop, span 0.05-1, δ slight fever economic coefficient, span 0-0.75.

The most according to claim 6, flue gas minimum discharge smoke elimination synergistic purification method, the method also includes procedure below: rinse System at regular intervals promotees poly-device to chilly phase transformation, the surface of multi-pollutant catcher and slight fever smoke eliminator is rinsed, rush Xian's water outlet and After condensation water in flue is recovered, it is back to absorption tower through draining system or delivers to serum producing system, or Substitute For Partial takes off Sulfur system use water.