CN209034070U - A flue gas cooling condensation dehumidification decontamination reheating whitening system - Google Patents

Abstract

Disappear white system the utility model discloses a kind of cooling dehumidification by condensation decontamination reheating of flue gas, which is made of flue gas deep cooler, flue gas condensing heat exchanger, smoke re-heater and cold source etc.；Flue gas depth cooling procedure provides heat source for flue gas reheat, heats main condensate, reduces desulfurizing tower and exports smoke temperature；Flue gas condensing process can heat main condensate, provide heat source for heat pump, recycle water resource, reduce humidity of flue gas；Flue gas reheat process reduces the relative humidity of smoke evacuation, visually eliminates white cigarette；Disappear white method the invention also discloses dehumidification by condensation decontamination reheating；The system and method innovates condensing heat exchanger structure, fluoroplastics, titanium alloy etc. are replaced using 316L, introduce force ventilation salt water tower and intelligent control system, reduce the cost and energy consumption of apparatus and system, while visually eliminating white cigarette, waste heat in step recovered flue gas, PM2.5, SO of 50% or more removing₃With 15% or more NO_x, take into account environmental benefit and economic interests.

Description

A flue gas cooling condensation dehumidification decontamination reheating whitening system

technical field

The utility model relates to the field of flue gas condensation, dehumidification, decontamination, heating and whitening, in particular to a fossil fuel, biomass fuel and waste incineration flue gas and wet flue gas after wet desulfurization to deeply remove pollutants and reheat to eliminate pollutants White smoke system.

Background technique

my country's economy continues to develop rapidly, the consumption of fossil energy is increasing year by year, the air quality is also deteriorating, and smog is raging all over the country. In order to control the emission of air pollutants, the thermal power industry has proposed ultra-low emission standards, requiring SO ₂ <20mg/m ³ . In order to achieve ultra-low emission standards, most thermal power plants use limestone/gypsum wet desulfurization to remove SO ₂ . Wet desulfurization can control the SO ₂ concentration within 20mg/m ³ , but the exhaust gas still contains a large amount of saturated water vapor, soluble salt aerosol with particle size less than 5 μm, SO ₃ /H ₂ SO ₄ , HF , HCl and other acid gases. The flue gas containing a large amount of saturated water vapor is discharged from the chimney and continuously diffuses and cools down, condenses and precipitates a large number of small droplets, refracts and scatters sunlight, and appears white plume, forming "visual pollution"; SO ₃ and soluble particles with a particle size of less than 5 μm Salt aerosols are an important part of secondary aerosols in the atmosphere, and secondary aerosols contribute 30-70% to the concentration of PM2.5; SO ₃ /H ₂ SO ₄ , HF, HCl and other acidic gases are in the tail smoke. Condensation and precipitation in the duct and chimney are extremely corrosive, which brings hidden dangers to the safe operation of the boiler. Therefore, the wet flue gas after wet desulfurization must be cooled and condensed before being discharged to reduce the water vapor content in the flue gas, and at the same time remove most of the soluble salt aerosol and SO ₃ /H ₂ SO ₄ , HF, HCl and other acid gases , eliminates white plumes in most weather conditions. Since 2016, Shanghai, Zhejiang, Handan, Tianjin and other places have successively issued policies, requiring coal-fired boilers to take corresponding measures to eliminate the phenomenon of colored plumes.

At present, most coal-fired boilers that have undergone flue gas whitening transformation have chosen the flue gas condensation reheating route. There are three types of flue gas condensation methods: condensation of circulating slurry in the desulfurization tower, condensation of direct contact spray of flue gas, and condensation of condensing heat exchanger. The spray condensation method can only condense and remove soluble salt aerosol and SO ₃ /H ₂ SO ₄ , HF, HCl and other acid gases through phase change, while the condensing heat exchanger can also remove the soluble salt aerosol through electrostatic adsorption and thermal surge effect. Dissolved salt aerosol and SO ₃ /H ₂ SO ₄ , HF, HCl and other PM-level pollutants are trapped on the surface of the heat exchanger, which has a better pollutant removal effect, so the condensing heat exchanger has a better development prospect.

_The condensing heat exchanger is accompanied by the condensation and precipitation ^{of acid} gases such as HF ^and HCl ⁱⁿ the process of cooling the flue gas. Local Cl ^- concentration can reach 20000ppm, pH is below 3, even nickel-based alloys are severely corroded, resulting in corrosion cracking. At present, the new service flue gas condensing heat exchangers are all made of fluoroplastics or titanium alloys. The cost of fluoroplastic/titanium alloy heat exchanger is more than 5 times that of ordinary stainless steel heat exchanger, and the thermal conductivity is much lower than that of stainless steel, resulting in large heat exchanger volume, large smoke and wind resistance, and high initial investment and operating costs. It brings huge resistance to the development of flue gas condensation, decontamination, reheating and whitening technology. There is an urgent need in the market for a condensing heat exchanger that can resist condensate corrosion, has high thermal conductivity, low cost, and low operating cost to meet the flue gas whitening needs of many coal-fired units.

The condensate of the initial condensation of wet flue gas after fossil fuel combustion or wet desulfurization contains a large amount of H ⁺ , Cl ^- , SO ₄ ^2- , F ^- and so on. The ion concentration will be diluted to below 200ppm. Design a new type of condensing heat exchanger and flue gas reheating heat exchanger, innovate the structure of the condensing heat exchanger, use the upper condensed water to dilute the condensate initially analyzed, and set up multiple real-time online detection devices for active ions to detect heat exchange The active ion concentration of each part of the device is controlled, and the active ion concentration is controlled below 1000ppm by means of spraying, so as to meet the requirements of most low-temperature corrosion-resistant materials, making stainless steel, aluminum alloy, copper alloy and other materials with high thermal conductivity It can be used safely for a long period of time. Heat exchangers made of high thermal conductivity materials such as stainless steel, aluminum alloys, and copper alloys have high heat transfer coefficients, small volumes, and low smoke and air resistance. The initial investment and operating costs are much lower than fluoroplastics and titanium alloy heat exchangers. It greatly promotes the promotion of flue gas condensation reheating and whitening technology, and further reduces the emission of PM-level pollutants by more than 50% on the basis of ultra-low emissions, making a huge contribution to defending the blue sky and reducing smog.

SUMMARY OF THE INVENTION

In order to reduce the price and operating cost of the flue gas condensation dehumidification decontamination heating whitening device and promote the development of flue gas condensation whitening technology, the purpose of this utility model is to provide a flue gas cooling condensation dehumidification decontamination reheating whitening system, The utility model solves the problem of high construction and operation cost of a whitening system, introduces a variety of cold sources, recycles and utilizes the waste heat of flue gas in steps, removes pollutants and recycles water resources while eliminating white smoke, and promotes condensation, dehumidification and whitening of flue gas. The development of technology contributes to the mitigation and elimination of smog.

In order to achieve the above purpose, the utility model adopts the following technical solutions:

A flue gas cooling, condensation, dehumidification, decontamination, reheating and whitening system, comprising a flue gas deep cooler 1, an electrostatic precipitator 2, an induced draft fan 3, a desulfurization tower 4, a cold source 5, a flue gas condensation heat exchanger 6, and a sedimentation tank 7. Desulfurization tower process water tank 8, flue gas reheater 9, chimney 10, condensate heater 11, auxiliary heating heater 12, No. 7 low-heating 13, No. 8 low-heating 14 and intelligent control system 15; flue gas depth The flue gas outlet of the cooler 1 is connected to the electrostatic precipitator 2, the induced draft fan 3 and the desulfurization tower 4 in sequence, and the wet saturated flue gas outlet of the desulfurization tower 4 is connected to the wet saturated flue gas inlet of the flue gas condensing heat exchanger 6, and the flue gas is condensed and exchanged. The wet saturated flue gas outlet of the heater 6 is connected to the wet saturated flue gas inlet of the flue gas reheater 9, the outlet of the flue gas reheater 9 is connected to the chimney 10, and the inlet and outlet water of the heat exchanger in the flue gas condensation heat exchanger 6 is collected. The tank is connected to the cold source 5, the condensate outlet at the bottom of the flue gas condensing heat exchanger 6 is connected to the inlet of the sedimentation tank 7, and the sedimentation tank 7 is connected to the desulfurization tower process water tank 8; The condensed water heater 11 is connected to the other, and the other is connected to the flue gas reheater 9. The condensed water heater 11 and the cold working fluid outlet of the flue gas reheater 9 are both connected to the cold working fluid inlet of the flue gas deep cooler 1, and are connected with the flue gas. The water circuit of the deep cooler 1 forms a circulation loop; the pipeline connecting the flue gas deep cooler 1 and the flue gas reheater 9 is provided with an auxiliary heat heater 12; the cold source 5 is mainly condensed water 5-1 and a heat pump 5 -2 and cooling tower 5-3; the exhaust smoke from the boiler body first enters the deep flue gas cooler 1, and the waste heat of the flue gas at 150°C to 90°C in the flue gas is recovered, which is used to heat the main condensate 5-1 and the reheated flue gas , the flue gas enters the electrostatic precipitator 2, the induced draft fan 3, and the desulfurization tower 4 in turn; the wet saturated flue gas at the outlet of the desulfurization tower 4 enters the flue gas condensing heat exchanger 6, and the flue gas condensing heat exchanger 6 utilizes the main condensed water 5- 1. The circulating water of the evaporator of the heat pump 5-2 and the circulating water of the cooling tower 5-3 are used as the cold source to condense the flue gas to 48℃～30℃; the condensate collected by the flue gas condensation heat exchanger 6 is discharged into the sedimentation tank 7 After treatment, it is discharged into the desulfurization tower process water tank 8; the wet saturated flue gas at the outlet of the flue gas condensing heat exchanger 6 enters the flue gas reheater 9, and the flue gas is removed by the flue gas waste heat at 150°C to 90°C and the low-pressure extraction steam of the steam turbine. Heating to 60℃～85℃ can reduce the relative humidity of exhaust smoke, prevent water vapor from condensing to form small droplets during the process of diffusion and cooling, and eliminate white smoke visually.

The flue gas deep cooler 1 is arranged before the electrostatic precipitator 2, and uses the alkaline fly ash in the flue gas to synergistically adsorb and remove the sulfuric acid condensed and precipitated on the surface of the heat exchanger; The ash has good wear-reducing performance and plays a role in rectification; the first 4 to 32 rows of H-finned tubes along the flue gas flow direction account for more than 50% of the total number of rows, and carbon steel is used for the subsequent H-finned tubes. The sheet tube is made of ND steel to improve the resistance to acid dew point corrosion; a hot water recirculation loop 1-1 is set between the inlet and outlet of the flue gas deep cooler 1. When the boiler is started or the boiler load is low, the hot water is used. In the recirculation method, the heated hot water is mixed with the low-temperature water at the inlet of the heat exchanger, so that the inlet water temperature is maintained above 70 °C, and the wall temperature of the flue gas deep cooler 1 is increased to avoid serious sulfuric acid dew point corrosion; Part of the working fluid heated by the flue gas deep cooler 1 is sent to the condensate heater 11 to heat the main condensate, reduce the use of the low-pressure extraction steam of the steam turbines of No. It is sent to the flue gas reheater 9 to heat the low-temperature wet saturated flue gas at the outlet of the flue gas condensing heat exchanger 6; when the water temperature at the outlet of the flue gas deep cooler 1 is low or the flue gas reheating temperature is high, the auxiliary heating is activated The device 12 uses the low-pressure extraction steam of the steam turbine to heat the circulating working fluid sent to the flue gas reheater 9 .

The flue gas condensing heat exchanger 6 is arranged after the desulfurization tower 4, and the flue gas condensing heat exchanger 6 is in the shape of a square tower, and the wall is lined with fluoroplastic or glass flake glue; Select 430, 439 ferritic stainless steel, 316L, 317L austenitic stainless steel and 2205, 2507 duplex stainless steel; the wet saturated flue gas at the outlet of desulfurization tower 4 enters the flue gas condensing heat exchanger 6 obliquely downward from the lower inlet, and the inclined The angle is 12-20° from the horizontal direction, the flue gas flows upward in the flue gas condensing heat exchanger 6, and the condensate flows downward under the action of gravity and collects in the condensate storage pool; the bottom of the flue gas condensing heat exchanger 6 is In the condensate storage pool, a condensate agitator 6-1 is arranged on the wall of the condensate storage pool to prevent the insoluble matter in the condensate from scaling on the wall of the flue gas condensing heat exchanger 6; the bottom of the condensate storage pool is provided with a condensate discharge Pipe 6-2, discharges the condensate to the sedimentation tank 7, so that the level of the condensate is maintained in the set interval; the upper layer of the condensate storage tank is provided with a condensate circulating pump 6-3, and the condensate circulating pump 6-3 is connected to the online spray The flushing system 6-5 pumps the condensate into the online spray flushing system 6-5. The online spray flushing system 6-5 has nozzles arranged on the inner wall of the flue gas condensing heat exchanger 6; the active ion concentration online monitoring device 6- 4. There is a sampling gun that goes deep into the stainless steel light tube heat exchanger, which can monitor the surface active ion concentration at different positions on the tube wall online; the online spray flushing system 6-5 is based on the online monitoring device for active ion concentration. Surface active ion concentration, spray condensate to the pipe wall area where the active ion concentration is higher than 1000ppm, dilute to reduce the active ion concentration, and regularly rinse the surface of the mist eliminator 6-6 and the stainless steel light pipe to avoid scaling; mist eliminator 6 -6 is arranged at the outlet of the flue gas condensing heat exchanger 6, and adopts a tube bundle type or baffle type mist eliminator to ensure that the amount of droplets entrained in the outlet flue gas is controlled below 75mg/ ^m3 .

The flue gas condensing heat exchanger 6 is divided into 2 to 6 grades of stainless steel light pipe heat exchangers along the flue gas flow direction. The temperature difference between the working fluid in and out of the flue gas condensing heat exchanger 6 is small and the latent heat of water vapor in the flue gas is huge. Therefore, The flow rate of the working medium is huge. In order to reduce the flow rate of the working medium in the flue gas condensing heat exchanger 6 and reduce the flow resistance of the working medium, the flue gas condensing heat exchanger 6 is divided into 2 to 6 grades of stainless steel light pipe heat exchange along the flue gas flow direction. Each stage stainless steel bare tube heat exchanger is equipped with independent inlet and outlet water headers; the inlet flue temperature of the first stage stainless steel bare tube heat exchanger is the highest, and the main condensate 5-1 is used as the working fluid, and the waste gas in the flue gas is recovered. High-grade heat energy, the temperature of the main condensate water is above 42 ℃, for the unit without main condensate water, the working fluid of the first-stage stainless steel bare tube heat exchanger is to use heat pump 5-2 evaporator circulating water or cooling tower 5-3 circulating water. The 2nd, 3rd, and 4th grade stainless steel bare tube heat exchangers can choose heat pump 5-2 evaporator circulating water or cooling tower 5-3 circulating water according to the needs; stainless steel bare tube heat exchangers use heat pump 5-2 evaporator circulating water as the working fluid , the heat pump 5-2 takes heat from the saturated wet flue gas, and heats the return water to above 60°C for district heating.

The cooling tower 5-3 adopts a natural ventilation cooling tower, a mechanical ventilation cooling tower, a fog-eliminating water-saving mechanical ventilation tower or a mechanical ventilation salt water cooling tower; when cooling the circulating water, the cooling tower 5-3 mainly relies on the evaporation of water to absorb heat Cooling down, causing a large amount of water vapor to return to the atmosphere; although the flue gas condensing heat exchanger 6 condenses and removes a large amount of water vapor from the flue gas, reduces the humidity of the exhaust gas, and reduces the discharge of water vapor from the chimney to the atmosphere, but the cooling The tower 5-3 discharges the same amount of water vapor to the atmosphere again in the process of cooling the circulating water, which makes it difficult to achieve the purpose of condensing and dehumidifying the flue gas; when the cooling tower 5-3 selects mechanical ventilation salt water cooling tower and fog elimination The water-saving mechanical ventilation tower can reduce the evaporation water of the cooling tower by more than 30% and achieve the goal of dehumidification; the mechanical ventilation salt water cooling tower changes the circulating working fluid from water to a CaCl ₂ solution with a mass concentration of 15% to 30%, and the freezing point of the solution drops. To below -30℃, when the outdoor temperature is lower than 0℃ in winter, the working fluid temperature of the mechanical ventilation brine cooling tower is reduced to below 10℃, there is no need to worry about the risk of icing, which is much lower than that of the cooling tower with water as the working medium. 20 ℃, and the water consumption of the cooling tower is 30% lower than that of the cooling tower with water as the working medium, and the amount of moisture exhaust is reduced by 30%; The greater the condensation heat transfer coefficient of 6, the greater the heat transfer temperature difference, and the better the flue gas dehumidification effect; therefore, when the cooling tower 5-3 is cooled by mechanical ventilation brine, the flue gas whitening effect is the best.

The sedimentation tank 7 is used to collect the condensate discharged from the bottom of the flue gas condensing heat exchanger 6. After the condensate is allowed to stand or is added with a flocculant, insoluble impurities are precipitated to the bottom of the tank. At this time, the condensate is weakly acidic and the concentration of pollutant ions is high. All are lower than 100ppm. After adding alkali to neutralize the pH of the condensate to 7, it can meet the industrial water requirements and discharge into the desulfurization tower process water tank 8 to provide process water for the desulfurization tower, significantly reduce desulfurization water consumption, and continuously reduce the flue gas condensing heat exchanger. 6 outlet flue gas temperature to achieve zero water consumption for desulfurization.

The flue gas reheater 9 is arranged after the flue gas condensing heat exchanger 6, takes the flue gas deep cooler 1 as a heat source, and forms a circulation loop with the water circuit of the flue gas deep cooler 1; when the flue gas deep cooler 1 exits When the water temperature is low or the flue gas reheating temperature is high, the auxiliary heating heater 12 is activated, and the low-pressure extraction steam of the steam turbine is used to heat the circulating water sent to the flue gas reheater 9; the flue gas reheater 9 is divided into three parts along the flue gas flow direction. Each stage is equipped with an independent inlet and outlet header. The first 4 to 12 rows use 2205, 2507 or 2707 light pipes to improve the corrosion resistance of small droplets containing active ions in the flue gas. The next 13 to 20 rows The 316L spiral finned tube is selected, and finally the ND steel spiral finned tube is selected; the high-temperature heating working medium first flows into the first 4 to 12 rows of light pipes in a downstream manner, and the wall temperature of the light pipe is maintained above 90 °C to ensure that the The small droplets have evaporated before contacting the tube wall, which improves the corrosion resistance of the flue gas reheater 9; the high-temperature heating working medium flows out from the first 4 to 12 rows of light tubes and enters the subsequent two-stage heating tubes in a countercurrent manner, improving the average heat exchange temperature difference.

The intelligent control system 15 receives the atmospheric real-time temperature, relative humidity and wind speed signals, and calculates the flue gas condensation temperature and flue gas reheat temperature with the lowest total energy consumption for eliminating white smoke; by adjusting the output of the heat pump 5-2 and the cooling tower 5 The frequency of the circulating water pump and the ventilation fan frequency of -3 control the outlet flue gas temperature of the flue gas condensing heat exchanger 6; The amount of heating steam regulates the flue gas temperature at the outlet of the flue gas reheater 9; observe whether the white smoke disappears through the online video monitoring device located at the outlet of the chimney 10, if the white smoke does not disappear, further fine-tune to reduce the flue gas condensation temperature and increase the flue gas reheating temperature. Heat temperature until the white smoke completely disappears, or the temperature and humidity of the chimney exhaust meet the local regulations of the local government; during the day, the atmospheric temperature is high at noon, increase the condensing temperature of the flue gas, reduce the reheating temperature of the flue gas, and the atmospheric temperature at night is low, Reduce the flue gas condensation temperature and increase the flue gas reheat temperature, so that the thermal energy obtained by the flue gas deep cooler 1 is used to heat the main condensate 5-1 as much as possible, and the energy consumption of the whitening system is reduced.

In summer, the atmospheric temperature is high and the water vapor holding capacity is strong. The exhaust smoke from the boiler body enters the flue gas deep cooler 1 and is cooled to 90°C, and then enters the low-low temperature dust collector 2, the induced draft fan 3 and the desulfurization tower 4. The exhaust gas discharged from the desulfurization tower 4 The wet saturated flue gas at 56°C to 48°C enters the flue gas condensation heat exchanger 6 and condenses to 44°C to 30°C, and then enters the flue gas reheater 9 to be reheated to above 60°C to visually eliminate white smoke. Local regulations stipulate that when reheating is not required, the flue gas reheater 9 is cancelled; in winter, the atmospheric temperature is low, the water vapor holding capacity is poor, and white smoke is easily formed. It enters the flue gas condensing heat exchanger 6 to be condensed to 44°C to 30°C, and then enters the flue gas reheater 9 to be reheated to above 72°C to visually eliminate white smoke.

The method for condensing, dehumidifying, decontaminating, reheating, and whitening the flue gas cooling, condensation, dehumidification, decontamination, and reheating whitening system includes three steps of deep cooling of flue gas, condensation, dehumidification and decontamination of flue gas, and reheating and whitening of flue gas;

Step 1: Deep cooling of flue gas:

Before the electrostatic precipitator 2 is arranged in the flue gas deep cooler 1, the flue gas is cooled from 150 ℃ to 120 ℃ to 90 ℃, and the waste heat of 150 ℃ to 90 ℃ in the flue gas is recovered in steps to heat the main condensate 5-1, Provide heat source for flue gas reheating;

Step 2: Flue gas condensation dehumidification and decontamination:

The flue gas condensing heat exchanger 6 is arranged after the desulfurization tower 4, and uses the main condensed water 5-1, the heat pump 5-2 and the cooling tower 5-3 as the cold source, so that the water vapor in the flue gas is condensed in the flue gas condensing heat exchanger. 6. Condensation and precipitation on the wall surface, lowering to 48℃～30℃, reducing the moisture content of flue gas; 56℃～48℃ wet saturated flue gas at the outlet of desulfurization tower 4 heats the main condensate water at a temperature of 5℃～10℃, and is used for heat pump 5 -2 Provide high-quality heat source at 20℃～40℃, and heat pump 5-2 will be used for external central heating after heat extraction;

Step 3: Reheating and whitening of flue gas:

The flue gas reheater 9 is arranged after the flue gas condensing heat exchanger 6, and heats the wet saturated flue gas from which part of the water vapor has been removed from 48°C to 30°C to 54°C to 72°C, and becomes superheated, lowering the chimney. The relative humidity of the exhaust smoke makes the temperature of the water vapor in the exhaust smoke always higher than the saturation temperature under the partial pressure during the process of diffusion and cooling, so as to prevent the water vapor in the exhaust smoke from condensing and forming white mist when it diffuses in the atmosphere;

The deep cooling of flue gas can recover the waste heat of 150℃～90℃ in the flue gas step by step, and send it to the regenerative system or be used for reheating the flue gas, so as to improve the efficiency of the boiler and reduce the coal consumption for power generation; the deep cooling of the flue gas can significantly reduce the condensation of the flue gas. The cost of the heat exchanger 6, if the high-temperature flue gas above 130°C is directly sent to the desulfurization tower 4, the high-grade thermal energy will be converted into the latent heat of low-grade steam at about 50°C, resulting in energy waste, and the desulfurization tower 4. The flue gas temperature at the outlet increases, the cooling range required for flue gas condensation increases, the heat exchange area of the flue gas condensing heat exchanger 6 increases, and the cost of the whitening system increases; during the deep cooling process of the flue gas, the fly ash can also condense and adsorb 80 % SO ₃ , Hg ²⁺ , which has potential environmental benefits; the sensible heat in the flue gas in the wet desulfurization process is converted into the latent heat of water vapor in the wet saturated flue gas, and the flue gas depth is arranged in front of the electrostatic precipitator 2 The cooler 1 significantly reduces the sensible heat in the flue gas, thereby reducing the temperature of the saturated flue gas at the outlet of the desulfurization tower 4, thereby reducing the volume of the flue gas condensing heat exchanger 6; the flue gas condensing heat exchanger 6 needs to be made of materials above 316L , and the flue gas deep cooler 1 only needs carbon steel and ND steel. The unit price of the former is more than 4 to 6 times that of the latter. Therefore, a flue gas deep cooler 1 is installed in front of the electrostatic precipitator 2 to replace part of the flue gas condensation. Heat exchanger 6 to reduce the cost of the whitening system; deep cooling of the flue gas has the triple function of recovering energy, reducing the cost of whitening and synergistically removing pollutants;

The flue gas condensation heat exchanger 6 recovers part of the low-temperature waste heat, which has energy-saving benefits; the flue gas condensation process is accompanied by electrostatic adsorption, thermal surge effect and water vapor condensation and adsorption, which can remove more than 50% of the PM2.5 in the flue gas. Level of fine particles and more than 15% NO _x and SO ₃ , which have environmental protection benefits; a large amount of weakly acidic condensate is obtained during the flue gas condensation process, which is used as desulfurization process water after treatment, saving water resources; flue gas condensation can reduce the humidity of exhaust gas. , the four-fold function of synergistic removal of pollutants, recovery of water resources and recovery of energy;

Flue gas reheating can improve the diffusivity of flue gas and avoid the chimney corrosion and chimney rain problems caused by the direct emission of wet saturated flue gas.

The innovation points, advantages and positive effects of the present utility model are:

1. A flue gas cooling condensation dehumidification decontamination reheating and whitening system of the present utility model is mainly composed of a flue gas deep cooler, a flue gas condensing heat exchanger and a flue gas reheater, and heats the flue gas while whitening it. The main condensate is used to recover the waste heat of the flue gas; according to the conservation of the total amount of cooling and heat release of the flue gas, the low-grade alloy before the electrostatic precipitator is used to replace the high-grade alloy after the desulfurization tower, which reduces the cost of the flue gas whitening system.

2. The flue gas condensing heat exchanger of the present invention has an innovative heat exchanger structure. The wet and saturated flue gas flows upward in the heat exchanger, and the condensate flows downward along the wall of the heat exchanger under the action of gravity, and the upper part of the heat exchanger is utilized. The condensate whose active ion concentration is lower than 100 ppm dilutes the pre-elution condensate whose active ion concentration is higher than 10000 ppm in the inlet area of the heat exchanger, controls the active ion concentration on the surface of the heat exchanger below 1000 ppm, and sets the active ion concentration online monitoring The device can wash the area where the concentration of active ions exceeds the standard, so that the condensing heat exchanger can use 316L material to meet the long-term safe operation, without the use of expensive materials such as titanium alloy and fluoroplastic, and the thermal conductivity is increased by more than 3 times. The construction cost is reduced by more than 60%; the condensate is used as process water for the boiler unit after precipitation and neutralization treatment, which saves water resources.

3. The flue gas condensing heat exchanger of a flue gas cooling condensation dehumidification decontamination reheating and whitening system of the present invention divides the heat exchanger into 2 to 6 levels along the flue gas flow direction, and each level has an independent The inlet and outlet headers can be respectively led to the main condensate water, the circulating water of the heat pump evaporator, and the circulating water of the cooling tower, which expands the scope of the cold source and recovers part of the latent heat of the water vapor in the flue gas.

4. The flue gas deep cooler and flue gas condensing heat exchanger of a flue gas cooling condensation dehumidification decontamination reheating and whitening system of the present utility model can respectively remove more than 50% _of SO3 while cooling the flue gas. , Hg and more than 50% of PM2.5 particulate matter and more than 15% of NO _x , SO ₃ , further reduce pollutant emissions on the basis of ultra-low emissions, and have environmental protection benefits.

5. The flue gas cooling, condensation, dehumidification, decontamination, decontamination, and reheating whitening system of the present utility model introduces the mechanical ventilation brine tower into the flue gas for whitening for the first time. The use of mechanical ventilation brine tower alleviates the problem of large water consumption in traditional cooling towers, and the dehumidification of chimney exhaust is transferred to the atmosphere through the cooling tower; the freezing point of brine can reach above minus 30 °C, so there is no need to worry about the problem of freezing, and the packing area is increased. The post-circulation working fluid can work in the range of 0℃～10℃, which increases the heat exchange temperature difference and condensation heat transfer coefficient of the condensing heat exchanger, and can reduce the weight by 50% compared with the traditional condensing heat exchanger; When the flue gas is condensed below 30°C, the circulating water of the cooling tower and the atmospheric temperature are lowered synchronously. When the atmospheric temperature is lower than 0°C, complete visual whitening can still be achieved.

6. A flue gas cooling, condensation, dehumidification, decontamination, reheating and whitening system of the present invention adopts an intelligent control system. According to the atmospheric temperature and humidity, the flue gas condensation temperature and flue gas reheat temperature are adjusted in real time, and according to the real-time temperature and humidity of the chimney outlet. The video monitoring system feeds back and adjusts the condensing temperature and reheating temperature, and uses the heat obtained by the flue gas deep cooler to heat the main condensate water as much as possible, reducing the power consumption of fans and pumps, and achieving the lowest total system energy consumption. Breathe white. Adopting the idea of system energy saving, through the optimization of the control system, the cost of eliminating waste is reduced, and both environmental protection and economic benefits are taken into account.

Description of drawings

Fig. 1 is the system diagram of the flue gas cooling, condensation, dehumidification, decontamination, reheating, and whitening system of the present invention.

Figure 2 is a schematic diagram of the flue gas condensation heat exchanger of the flue gas cooling condensation dehumidification decontamination reheating and whitening system of the present invention.

Fig. 3 is the water side connection schematic diagram of the flue gas condensing heat exchanger of the flue gas cooling condensation dehumidification decontamination reheating whitening system of the present invention, wherein: Fig. 3a is the connection schematic diagram when the main condensate water and the cooling tower are used as the cold source , Figure 3b is a schematic diagram of the connection when the main condensate water and the heat pump are used as the cold source, and Figure 3c is a schematic diagram of the connection when the heat pump and the cooling tower are used as the cold source.

4 is a schematic diagram of the water side connection of the flue gas reheater of the flue gas cooling condensation dehumidification decontamination reheating and whitening system of the present invention.

5 is a schematic diagram of the control logic of the intelligent control system of the flue gas cooling condensation dehumidification decontamination, reheating and whitening system of the present invention.

Detailed ways

The utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a flue gas cooling condensation dehumidification decontamination reheating and whitening system of the present invention includes a flue gas deep cooler 1, an electrostatic precipitator 2, an induced draft fan 3, a desulfurization tower 4, a cold source 5, a smoke Gas condensing heat exchanger 6, sedimentation tank 7, desulfurization process water tank 8, flue gas reheater 9, chimney 10, condensate heater 11, auxiliary heating heater 12, No. 7 low-heating 13, No. 8 low-heating 14 and Intelligent control system 15; the exhaust smoke from the boiler body first enters the flue gas deep cooler 1, and the waste heat of the flue gas at 150°C to 90°C in the flue gas is recovered, which is used to heat the main condensate 5-1 and reheat the flue gas; after the flue gas Enter the electrostatic precipitator 2, the induced draft fan 3, and the desulfurization tower 4 in turn; the wet saturated flue gas at the outlet of the desulfurization tower 4 enters the flue gas condensing heat exchanger 6, and the flue gas condensing heat exchanger 6 utilizes the main condensed water 5-1 and the heat pump 5. The circulating water of the evaporator of -2 and the circulating water of the cooling tower 5-3 are used as cold sources to condense the flue gas to 48℃～30℃; the condensate collected by the flue gas condensing heat exchanger 6 is discharged into the sedimentation tank 7, and discharged after treatment Enter the desulfurization tower process water tank 8; the wet saturated flue gas at the outlet of the flue gas condensing heat exchanger 6 enters the flue gas reheater 9, and the flue gas is heated to 60 ℃ by using the residual heat of the flue gas at 150 ℃ ~ 90 ℃ or the low-pressure extraction steam of the steam turbine ～85℃, reduce the relative humidity of flue gas, avoid condensation of water vapor to form small droplets during the process of diffusion and cooling, and eliminate white smoke visually.

As shown in FIG. 2 , the flue gas condensing heat exchanger 6 is arranged after the desulfurization tower 4 . The flue gas condensing heat exchanger 6 is in the shape of a square tower, and the outer shell can be lined with fluoroplastic or glass flake glue; the interior adopts a stainless steel light pipe heat exchanger, and the stainless steel material can be selected from 304, 316L, 317, 2205, 2507, 2707 and other stainless steel The wet saturated flue gas of the desulfurization tower 4 exit enters the flue gas condensing heat exchanger 6 obliquely downward from the inlet of the lower part, and the inclination angle is 12～20 ° with the horizontal direction, and the flue gas rises in the flue gas condensing heat exchanger 6 afterwards. Flow to the upper outlet, the condensate flows downward under the action of gravity and collects in the condensate storage pool; the bottom of the flue gas condensing heat exchanger 6 is the condensate storage pool, and the condensate agitator (6-1) is arranged on the wall of the condensate storage pool. ) to prevent the insoluble matter in the condensate from scaling on the wall of the flue gas condensing heat exchanger 6; the condensate storage tank bottom is provided with a condensate discharge pipe (6-2), the condensate is discharged to the sedimentation tank 7, the condensate The liquid water level is maintained in the set range; a condensate circulating pump (6-3) is installed on the upper layer of the condensate storage tank, and the condensate is pumped into the online spray and flushing system (6-5); the active ion concentration online monitoring device (6-4) ) There is a sampling gun that penetrates into the stainless steel light tube heat exchanger, which can monitor the active ion concentration on the surface of the tube wall at different positions online; the online spray flushing system (6-5) is based on the active ion concentration online monitoring device (6-4) The collected active ion concentration on the surface of the tube wall, spray condensate to the tube wall area where the active ion concentration is higher than 1000ppm, dilute to reduce the active ion concentration, and regularly flush the demister (6-6) and the surface of the heat exchanger to avoid Scaling; the mist eliminator (6-6) is arranged at the outlet of the flue gas condensing heat exchanger 6, and a tube bundle or baffled mist eliminator can be selected to ensure that the amount of droplets entrained in the outlet flue gas is controlled below 75mg/ ^m3 .

As shown in FIG. 3 , the flue gas condensing heat exchanger 6 is divided into 2-6 grades of stainless steel light pipe heat exchangers along the flue gas flow direction. The temperature difference between the inlet and outlet of the working fluid in the flue gas condensing heat exchanger 6 is small and the latent heat of water vapor in the flue gas is huge, so the flow rate of the working fluid is huge. , along the flue gas flow direction, the flue gas condensing heat exchanger 6 is divided into 2 to 6 grades of stainless steel bare tube heat exchangers, and each grade of stainless steel bare tube heat exchangers is provided with independent inlet and outlet water headers. As shown in Figure 3a, the main condensate water 5-1 is selected as the working fluid of the first-stage stainless steel light tube heat exchanger to recover the high-grade heat energy in the flue gas, and the main condensate water is heated from 35 °C to 45 °C; Grade 3 and Grade 4 stainless steel bare tube heat exchangers use natural ventilation cooling tower circulating water as the working fluid, and discharge the latent heat of water vapor directly into the atmosphere. As shown in Figure 3b, the main condensate 5-1 is selected as the working fluid of the first-stage stainless steel bare tube heat exchanger to recover high-grade heat energy in the flue gas; the second, third and fourth stages of stainless steel bare tube heat exchange The heat pump 5-2 is used for circulating water in the evaporator, and the heat pump 5-2 utilizes the latent heat of water vapor in the flue gas for central heating. As shown in Figure 3c, the working fluid of the first and second stainless steel light tube heat exchangers is the circulating water of the evaporator of heat pump 5-2, which is used for external central heating; the third and fourth stages of stainless steel light pipe The working fluid of the heat exchanger adopts the circulating water of the mechanical ventilation brine cooling tower, and the latent heat of the water vapor is directly discharged into the atmosphere.

As shown in FIG. 4 , the flue gas reheater 9 is arranged after the flue gas condensing heat exchanger 6 , takes the flue gas deep cooler 1 as a heat source, and forms a circulation loop with the water circuit of the flue gas deep cooler 1 . When the outlet water temperature of the flue gas deep cooler 1 is low or the flue gas reheating temperature is high, the auxiliary heating heater 12 is activated, and the low-pressure extraction steam of the steam turbine is used to heat the circulating water sent to the flue gas reheater 9; the flue gas reheating The device 9 is divided into three stages along the flow direction of the flue gas, and each stage is provided with an independent inlet and outlet header. The first 4 to 12 rows use 2205, 2507 or 2707 light pipes to improve the resistance to small droplets containing active ions in the flue gas. 316L spiral finned tubes are used for the next 13 to 20 rows, and finally ND steel spiral finned tubes are used; the high temperature heating medium first flows into the first 4 to 12 rows of light pipes in a downstream manner to maintain the wall temperature of the light pipes. Above 90°C, it is ensured that the small droplets in the flue gas have evaporated before contacting the tube wall, and the corrosion resistance of the flue gas reheater 9 is improved; In the subsequent two-stage heating tubes, the average heat exchange temperature difference is increased.

As shown in FIG. 5 , the intelligent control system 15 receives the atmospheric real-time temperature, relative humidity and wind speed signals, and calculates the flue gas condensation temperature and flue gas reheat temperature with the lowest total energy consumption for eliminating white smoke. By adjusting the output of the heat pump 5-2 and the frequency of the circulating water pump of the cooling tower 5-3 and the frequency of the ventilation fan, the outlet flue gas temperature of the flue gas condensing heat exchanger 6 is controlled; by adjusting the flue gas deep cooler assigned to the condensate heater 11 The high temperature water output of 1 and the heating steam volume of the auxiliary heating heater 12 regulate the outlet smoke temperature of the flue gas reheater 9; observe whether the white smoke disappears through the online video monitoring device located at the outlet of the chimney 10, if the white smoke does not disappear, Further fine-tune the reduction of the flue gas condensation temperature and increase the flue gas reheat temperature until the white smoke completely disappears, or the temperature and humidity of the chimney exhaust meet the local regulations of the local government; in a day, when the atmospheric temperature is high at noon, increase the flue gas condensation temperature, Reduce the flue gas reheat temperature, the atmospheric temperature at night is low, reduce the flue gas condensation temperature, and increase the flue gas reheat temperature, so that the heat energy obtained by the flue gas deep cooler 1 can be used to heat the condensed water as much as possible. 5-1, reduce consumption. The energy consumption of the white system.

Claims (6)

1. The white system 1. a kind of cooling dehumidification by condensation decontamination reheating of flue gas disappears, it is characterised in that: including flue gas deep cooler (1), Electrostatic precipitator (2), air-introduced machine (3), desulfurizing tower (4), cold source (5), flue gas condensing heat exchanger (6), precipitation pond (7), desulfurization Tower process water tank (8), smoke re-heater (9), chimney (10), condensation water heater (11), auxiliary hot heater (12), No. 7 it is low plus (13), No. 8 low plus (14) and intelligent control systems (15)；The exhanst gas outlet of flue gas deep cooler (1) is sequentially communicated electrostatic and removes Dirt device (2), air-introduced machine (3) and desulfurizing tower (4), the wet saturated flue gas outlet flue gas condensing heat exchanger (6) of desulfurizing tower (4) Wet saturated flue gas entrance, the wet saturated flue gas of the wet saturated flue gas outlet smoke re-heater (9) of flue gas condensing heat exchanger (6) The Inlet and outlet water header of entrance, smoke re-heater (9) outlet chimney (10), the heat exchanger in flue gas condensing heat exchanger (6) connects Logical cold source (5), the condensate outlet of flue gas condensing heat exchanger (6) bottom are connected to precipitation pond (7) entrance, and precipitation pond (7) is even Unconventional sulphur tower process water tank (8)；The hot working fluid outlet of flue gas deep cooler (1) divides two-way, is connected to condensation water heater all the way (11), another way connection smoke re-heater (9), condensation water heater (11) are connected to smoke re-heater (9) cold sender property outlet The cold working medium entrances of flue gas deep cooler (1) form circulation loop with the water route of flue gas deep cooler (1)；Flue gas depth Auxiliary hot heater (12) are provided on the pipeline that cooler (1) is connected to smoke re-heater (9)；It is condensed based on the cold source (5) Water (5-1), heat pump (5-2) and cooling tower (5-3).
2. The white system 2. the cooling dehumidification by condensation decontamination reheating of a kind of flue gas according to claim 1 disappears, it is characterised in that: described Flue gas deep cooler (1) is arranged in front of electrostatic precipitator (2), the Zhan Zongpai using H-type finned tube, along flow of flue gas direction Preceding 4~32 row H-type finned tube of several 50% or more selects carbon steel, and H-type finned tube thereafter selects ND Steel material, anti-to improve Acid dew piont corrosion ability；Setting setting hot water re-circulation circuit (1-1) between the inlet and outlet of flue gas deep cooler (1).
3. The white system 3. the cooling dehumidification by condensation decontamination reheating of a kind of flue gas according to claim 1 disappears, it is characterised in that: described Flue gas condensing heat exchanger (6) is arranged in after desulfurizing tower (4), and flue gas condensing heat exchanger (6) shape is square tower-like, wall surface liner Fluoroplastics or glass flake plasticine；Inside uses stainless steel bare tube heat exchanger, and stainless steel material selects 430,439 ferrite stainless Steel, 316L, 317L austenitic stainless steel and 2205,2507 two phase stainless steels；Flue gas condensing heat exchanger (6) bottom is condensate liquid Condensate liquid blender (6-1) is arranged on condensate liquid storage pool wall surface in storage pool, and condensate liquid stores bottom of pond portion and is equipped with condensate liquid discharge It manages (6-2), condensate liquid storage pool upper layer is arranged condensate circulation and pumps (6-3), and condensate circulation pumps the online spray punching of (6-3) connection System (6-5) is washed, is sprayed the nozzle that system (6-5) has setting in flue gas condensing heat exchanger (6) inner wall online；Active ion Concentration on-line monitoring device (6-4) has the sampling gun for being deep into stainless steel bare tube heat exchanger；It is cold that demister (6-6) is arranged in flue gas The outlet of solidifying heat exchanger (6), using bundled tube or baffle type mist eliminator, it is ensured that the control of exiting flue gas entrained drip amount exists 75mg/m³Below.
4. The white system 4. the cooling dehumidification by condensation decontamination reheating of a kind of flue gas according to claim 3 disappears, it is characterised in that: described Flue gas condensing heat exchanger (6) is divided into 2~6 grades of stainless steel bare tube heat exchangers, every level-one stainless steel bare tube heat exchanger along flue gas flow direction It is respectively provided with independent Inlet and outlet water header；The import smoke temperature highest of 1st grade of stainless steel bare tube heat exchanger, working medium select main condensate (5-1), for the unit of not main condensate, the 1st grade of stainless steel bare tube heat exchanger working medium selects heat pump (5-2) evaporator circulation Water or cooling tower (5-3) recirculated water, the 2nd, 3,4 grade of stainless steel bare tube heat exchanger select heat pump (5-2) evaporator to follow according to demand Ring water or cooling tower (5-3) recirculated water.
5. The white system 5. the cooling dehumidification by condensation decontamination reheating of a kind of flue gas according to claim 4 disappears, it is characterised in that: described Cooling tower (5-3) is using cooling stack, mechanical-draft cooling tower, the water-saving mechanical aeration tower of fog dispersal or force ventilation salt water Cooling tower.
6. The white system 6. the cooling dehumidification by condensation decontamination reheating of a kind of flue gas according to claim 1 disappears, it is characterised in that: described Smoke re-heater (9) is arranged in after flue gas condensing heat exchanger (6), and smoke re-heater (9) is divided into three-level along flow of flue gas direction, Every level-one is equipped with independent inlet and outlet header, and preceding 4~12 row selects 2205,2507 or 2707 light pipes, 13~20 rows later 316L spiral fin coil is selected, ND steel spiral fin coil is finally selected.