CN111457414A - Flue gas reheating system and method with on-line desalination function - Google Patents

Abstract

The invention relates to a flue gas reheating system with an online desalting function and a method thereof, wherein the system comprises a circulating washing water tank, a wet washing tower arranged above the circulating washing water tank, a first reheating evaporation tower and a second reheating evaporation tower, the lower ends of which are communicated with the wet washing tower, a purified flue gas adjusting tower communicated with the upper ends of the first reheating evaporation tower and the second reheating evaporation tower, and a direct exhaust flue arranged above the purified flue gas adjusting tower, wherein one side of the lower part of the wet washing tower is provided with an incineration flue gas inlet; the invention creatively realizes that the salt concentration of the high-salinity wastewater is reduced, the online desalting is realized, the emission of flue gas is ensured to reach the standard, white smoke plume is eliminated, and the environmental perception is improved in one set of system.

Description

Flue gas reheating system and method with on-line desalination function

technical field

The invention relates to a flue gas reheating system and method with on-line desalination function.

Background technique

In the current mainstream hazardous waste incineration processes at home and abroad, the treatment of incineration flue gas generally includes a wet scrubbing and acid removal process. This process is located after the bag filter and before the flue gas reheater in the incineration flue gas treatment process. The main function of the wet scrubbing process is to further remove the acid gas, salt or salt material, dust, etc. contained in the incineration flue gas. When the wet scrubbing process is used to remove acid and particulate matter, a circulating water pool is set below the scrubbing tower. The washing water exchanges heat with the high-temperature flue gas and removes the acid gas and particulate matter in the flue gas. Enter the next treatment process; at the same time, the temperature of the washing water rises, and after being cooled by the heat exchanger, it enters the circulating water pool, and the water in the circulating water pool is sprayed into the washing tower through the circulating pump to wash the flue gas, so as to be recycled.

As the number of times the flue gas is washed by the washing water cycle increases, the content of salts (usually sodium chloride, calcium chloride, calcium sulfate, etc.) in the circulating pool gradually increases, and these salts will crystallize out after reaching saturation. In this case, continue to use high-salt washing water to spray the flue gas into the washing tower through the circulating pump, which will cause the crystallization of salt substances in the pipeline, nozzle, inner wall of the tower, etc., blocking the pipeline and nozzle, reducing the volume of the tower and increasing the Smoke resistance, etc.

According to the current relevant laws and regulations, such waste water and waste salt are still hazardous waste, and in recent years, some unscrupulous business owners have secretly discharged this type of waste water in the factory in order to seek illegal benefits and take risks. Law enforcement agencies have sanctioned a number of illegal and criminal units and personnel.

There are two schemes currently in use:

Option 1: Some domestic processes spray such high-salt wastewater into the quenching tower of the previous process. This method will cause corrosion of the quenching tower, corrosion of flue gas pipes, blockage of flue gas pipes, etc. Long-term operation will cause the production line to stop production or even Equipment scrapped.

Option 2: Another process is to configure an independent high-salt wastewater treatment system for the high-salt wastewater in the circulating pool. At present, multi-effect evaporation, membrane concentration, electrochemistry, ion exchange and other technologies are used to achieve large-scale treatment and hazardous waste disposal. The unit mainly adopts the combined technology of membrane concentration + multi-effect evaporation. By configuring sedimentation tank, ultrafiltration device, butterfly reverse osmosis membrane group, multi-effect evaporation crystallizer, dryer, tubular heat exchanger and supporting pump group and pump station, through the concentrated production of ultrafiltration and reverse osmosis membrane group Water is subjected to multi-effect evaporation, and finally a dry salt residue is obtained for outsourcing treatment. The scheme adopts the combined technology of membrane concentration and multi-effect evaporation, which temporarily solves the problem of high-salt wastewater. However, because the system needs to design, purchase, and install sedimentation tanks, ultrafiltration devices, butterfly reverse osmosis membrane units, multi-effect evaporation crystallizers, dryers, tubular heat exchangers, and supporting pump sets, pump stations and other equipment and pipelines, The following disadvantages exist:

1. Calculated according to the design treatment scale of washing water of 50t/d, the investment cost of the device is about 5 million yuan, and the system investment cost is high;

2. The floor space is about 15m*12m*5m, and the system device occupies a large area;

3. The average annual electricity consumption is 90*104 kW·h, the annual operating cost is about 500,000 yuan, and the operating energy consumption is high;

4. The membrane concentration efficiency is 70%, and the concentration and evaporation salt production efficiency is low;

5. System cleaning is required for 2-3 months. The system cleaning is complicated and the operation and maintenance cost is high.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a flue gas reheating system and method with on-line desalination function, which can solve the problem of using washing circulating water to spray into the washing tower to wash the flue gas, and the salt substances in the circulating water pool gradually increase to form high The salt water will crystallize after reaching saturation.

The technical scheme adopted in the present invention is:

A flue gas reheating system with on-line desalination function, which comprises a circulating washing pool, a wet scrubbing tower arranged above the circulating washing pool, a first reheating evaporation tower and a second reheating tower whose lower end communicates with the wet scrubbing tower. The thermal evaporation tower, the purification flue gas conditioning tower connected with the upper ends of the first reheat evaporation tower and the second reheat evaporation tower, and the straight exhaust flue set above the purification flue gas conditioning tower, are on the lower side of the wet scrubbing tower A combustion flue gas inlet is provided.

Further, a filter device is connected to the circulating washing pool through a pipeline.

Further, the first reheat evaporation tower includes a first electric flue gas cut-off valve C, a first desalination unit, a first heating device, a first differential pressure detector, a first The temperature detector, the first salt-cleaning fan and the first electric flue gas cut-off valve B are provided with a first electric flue gas cut-off valve A on the air inlet pipeline of the first salt-cleaning fan.

Further, the second reheat evaporation tower includes a second electric flue gas cut-off valve C, a second desalination unit, a second heating device, a second differential pressure detector, a second The temperature detector, the second salt cleaning fan and the second electric flue gas cut-off valve B are provided with a second electric flue gas cut-off valve A on the air inlet pipeline of the second salt cleaning fan.

Further, a third temperature detector is arranged on the upper part of the wet scrubbing tower.

Further, the first heating device includes a first primary effect reheat evaporator and a first second effect reheat evaporator arranged in sequence along the flue gas flow direction.

Further, the second heating device includes a second primary effect reheat evaporator and a second second effect reheat evaporator arranged in sequence along the flue gas flow direction.

Further, the purifying flue gas conditioning tower includes a condensing and recycling water collection device, a cooling device and a fourth temperature detector, the condensation and recycling water collection device is located below the cooling device and communicated with the circulating washing pool, and the fourth temperature detector above the cooling device.

Further, the filtering device is an activated carbon filter tank, and a pressurized water pump is provided on the tank inlet pipeline of the activated carbon filter tank.

A flue gas reheating method with on-line desalination function, comprising the steps of:

Step 1. Close the second electric flue gas shut-off valve C, the second electric flue gas shut-off valve B, the first electric flue gas shut-off valve A and the first salt-cleaning fan, and open the first electric flue gas shut-off valve C, the first electric flue gas shut-off valve The flue gas cut-off valve B makes the first reheat evaporation tower in working state, and the circulating water in the circulating washing pool is sprayed into the wet washing tower to complete the wet washing and incineration of flue gas;

Step 2: The circulating washing water falls into the circulating washing pool, and the pH is adjusted to weakly alkaline by adding lye. At the same time, the circulating water in the pool is pumped by the water pump to the filter device for filtration, and the particulate matter and impurities are filtered to obtain the circulating washing pool. High-salt wastewater;

Step 3, the washed flue gas enters the first reheating evaporation tower, completes the heating and evaporation of flue gas and the crystallization of waste salt through the first primary effect reheating evaporator and the first second effect reheating evaporator, and enters the purification flue gas conditioning tower;

Step 4. The heated flue gas is passed through the cooling device in the purification flue gas adjustment tower to complete the cooling and condensation of the flue gas, and is discharged up to the standard through the straight exhaust flue;

The condensed water produced in step 5 and step 4 falls into the condensed and reused water collection device located at the bottom of the purification flue gas conditioning tower, and flows to the circulating washing pool for reuse through the pipeline; when the pressure difference detector in the first reheating evaporation tower When the detection shows that the pressure difference is greater than Pa, it is determined that the desalination requirements are met;

Step 6: The first reheating evaporation tower enters the demineralization state, take out the second demineralization insert and close the second demineralization unit, and the second primary effect reheating evaporator and the second second effect reheating evaporator Steam, open the second electric flue gas shut-off valve C, the second electric flue gas shut-off valve B, the first electric flue gas shut-off valve A, close the first electric flue gas shut-off valve C, the first electric flue gas shut-off valve B, the 2. Electric flue gas cut-off valve A, the incineration flue gas after wet scrubbing enters the second reheat evaporation tower, and steps 1 to 5 are repeated in the second reheat evaporation tower;

Step 7: After the first temperature detector shows that the temperature is lowered, open the first demineralization unit, put in the first demineralization insert, and pass steam into the first primary effect reheat evaporator and the first second effect reheat evaporator , start the first demineralizing fan to pass in hot dry air, and demineralize the first reheating evaporation tower. When the first pressure difference detector in the first reheating evaporation tower detects that the pressure difference is less than Pa, it is determined that the demineralization is completed. ;

Step 8: Turn off the first desalination fan and the first electric flue gas cut-off valve A, and cut off the steam in the first primary effect reheat evaporator and the first second effect reheat evaporator;

Step 9: After cooling, after the first temperature detector shows that the temperature has dropped, open the first demineralizing unit and take out the demineralizing insert, then immediately close the demineralizing unit, collect the waste salt and process it, at this time, the first reheating evaporation tower is completed. Desalination work, enter the quasi-working state;

Step 10: When the second reheating evaporation tower shows that it has reached the desalting state, repeat steps six to nine according to the same principle for the second reheating evaporation tower, and the first reheating evaporation tower and the second reheating evaporation tower are replaced in this way operation to realize flue gas reheating for on-line desalination.

The positive effects of the present invention are:

1. The present invention creatively realizes that in one system, the salt concentration of high-salt wastewater can be reduced, the on-line desalination can be realized, and the flue gas emission can be guaranteed to meet the standard, the white smoke plume can be eliminated, and the environmental perception can be improved.

2. Ingeniously use two-stage reheat evaporation to heat flue gas, evaporate water vapor, and precipitate waste salt, and then reduce the temperature of flue gas and condense steam through a cooling device, saving the current mainstream need to be configured separately. Membrane concentration + multi-effect evaporation The high procurement and later operation and maintenance costs of the high-salt wastewater treatment system combined with the technology minimize energy consumption, effectively reuse water resources, and save a lot of investment and operating costs.

3. Through innovative structural design, two reheating evaporation towers are used in parallel to achieve non-stop online desalination, avoiding the 2-3 months of system cleaning and back-spraying technology of the combined technology of membrane concentration and multi-effect evaporation. Due to the hidden danger of demineralization production line shutdown and equipment scrapping.

4. Through the detector and automatic control system configured in the system, the system only needs manual participation during online desalination, and only simple operations are performed on the desalination unit, which improves the safety and stability of the system and reduces the maintenance difficulty for operators. and labor intensity.

Description of drawings

Fig. 1 is the system flow chart of the present invention;

Fig. 2 is the structural representation when the first reheat evaporation tower of the present invention is in the working state;

3 is a schematic structural diagram of the first reheat evaporation tower of the present invention when it is in a demineralized state.

Detailed ways

As shown in Figures 1-3, the system of the present invention includes a circulating washing pool 100, a filtering device 200, a wet scrubbing tower 300, a first reheat evaporation tower 400, a second reheat evaporation tower 500, and a purification flue gas conditioning tower 600 and straight flue 700.

The circulating washing pool 100 is connected to the filtering device 200 through pipelines, the first reheat evaporation tower 400 and the second reheat evaporation tower 500 are arranged in parallel, the lower ends thereof are respectively connected with the upper outlet of the wet scrubbing tower 300, and the upper end outlets are respectively connected with the purified smoke The lower inlet of the gas conditioning tower 600 is connected, and the upper outlet of the purification flue gas conditioning tower 600 is connected with the straight exhaust flue 700 . A combustion flue gas inlet is arranged on the lower side of the wet scrubbing tower 300, and a third temperature detector 310 is arranged on the upper portion thereof.

The circulating water in the circulating washing pool 100 is pumped to the filter device 200 by the water pump for filtration, and the activated carbon filtered water with the particulate impurities removed is returned to the circulating washing pool 100 through the tank outlet pipeline. In this embodiment, the filter device 200 adopts an activated carbon filter tank, and may also be other primary or high-efficiency filter devices, such as ultrafiltration, sand filtration, membrane filtration and other technologies.

The circulating washing pool 100 is arranged below the hazardous waste incineration flue gas wet scrubbing tower 300. The circulating washing pool 100 is provided with an online pH analyzer and a liquid level gauge, and has a pH adjustment system and a liquid level control system; The device 200 is connected by pipelines to form a circulation pipeline, and the liquid inlet pipeline of the filtering device is provided with a pressurized water pump.

There are two outlets in the upper part of the wet scrubbing tower 300, which are respectively connected to the first reheat evaporation tower 400 and the second reheat evaporation tower 500 through flanges.

The first reheating evaporation tower 400 includes a first electric flue gas cut-off valve C410, a first first desalination unit 420, a first heating device, a first first differential pressure detector 450, The first first temperature detector 460, the first first salt cleaning fan 480 and the first electric flue gas cut-off valve B490, the first first salt cleaning fan 480 is communicated with the tower body of the first reheat evaporation tower 400 through pipelines , a first electric flue gas cut-off valve A470 is arranged on the pipeline, and a first demineralization insert plate 421 can be installed at the first demineralization part 420.

The second reheating evaporation tower 500 includes a second electric flue gas cut-off valve C510, a second desalination unit 520, a second heating device, a second second pressure difference detector 550, a second second pressure difference detector 550, a second The temperature detector 560, the second salt cleaning fan 580 and the second electric flue gas cut-off valve B590, the second salt cleaning fan 580 is communicated with the tower body of the second reheat evaporation tower 500 through a pipeline, and the pipeline is provided with There is a second electric flue gas cut-off valve A570, and a second demineralization insert plate 521 is installed at the position of the second demineralization part 520.

The first heating device includes a first first primary effect reheating evaporator 430 and a first first second effect reheating evaporator 440 arranged in sequence along the flue gas flow direction, and the second heating device includes sequentially arranged along the flue gas flow direction. The second primary effect reheat evaporator 530 and the second second effect reheat evaporator 540 .

The upper outlets of the first reheat evaporation tower 400 and the second reheat evaporation tower 500 are connected to the lower inlet of the purification flue gas conditioning tower 600 through flanges. The device 620 and the fourth and fourth temperature detectors 630 , the condensation and reuse water collection device 610 is located below the cooling device 620 and communicated with the circulating washing pool 100 , and the fourth and fourth temperature detectors 630 are located above the cooling device 620 . Specifically, the position of the condensed and recycled water collection device 610 should be slightly lower than the connection position of the first reheat evaporation tower 400, the second reheat evaporation tower 500 and the purification flue gas conditioning tower 600 to facilitate collection.

The key of the present invention is that the circulating washing pool 100 is arranged below the hazardous waste incineration flue gas wet scrubbing tower 300, and the water in the pool is mainly used to circulate and wash the hazardous waste incineration flue gas to remove acid gas and particulate matter in the flue gas.

The incineration flue gas enters the tower through the incineration flue gas inlet at the lower part of the wet scrubbing tower 300 and rises, and the circulating scrubbing water in the circulating scrubbing pool 100 sprays the circulating scrubbing water and flue gas acid substances into the tower through the pipeline, and the upper part of the wet scrubbing tower 300 A temperature detector 310 is provided, the amount of washing water is adjusted by detecting the temperature of the flue gas in the tower, and the temperature of the flue gas is reduced and controlled between 100°C and 110°C to form washing flue gas, in which impurities such as particulate matter fall into the circulating washing pool 100, The scrubbing flue gas continues to rise into the first reheating evaporation tower 400 or the second reheating evaporation tower 500 entrained by the brine steam; the wet scrubbing tower 300 is made of high-temperature glass fiber reinforced plastic, which has fire resistance and high temperature resistance; the first reheating evaporation tower 400 Or the body of the second reheating evaporation tower 500, the first and second primary effect reheating evaporators and the first and second second effect reheating evaporators are all made of stainless steel with good thermal conductivity and strong corrosion resistance. Do insulation treatment.

When the system is in use, the two reheat evaporation towers do not work at the same time. In this embodiment, the flue gas enters the first reheat evaporation tower 400 and the second reheat evaporation tower is in a non-working state as an example for description.

As shown in FIG. 2, the first reheat evaporation tower 400 is in the working state, the second reheat evaporation tower 500 is in the non-working state (desalting or closed state); the first electric flue gas cut-off valve C410 is in the open state, and the The first demineralization unit 420 is in a closed state, and the scrubbing flue gas enters the first reheat evaporation tower 400 to reach the first primary effect reheat evaporator 430 and the first second effect reheat evaporator 440, and the first primary effect reheat evaporator 440. 430 and the first two-effect reheat evaporator 440 are introduced into high-temperature steam through the air inlet pipe, and the flue gas is heated and washed with the heat exchange tube bundle. After reheating, the water vapor entrained in it evaporates, and the waste salt dissolved in the water vapor is precipitated and crystallized and attached to the outer wall of the heat exchange tube bundle; The electric flue gas cut-off valve B490 is in the open state, and the scrubbing flue gas is formed by the reheat evaporation process to form heated flue gas and continues to rise. The function of detecting the difference in flue gas pressure before and after evaporation is convenient for adjusting and controlling the flow rate of flue gas in the tower and judging whether the first reheating evaporation tower 400 should be demineralized. The first temperature detector 460 on the upper part of the differential pressure detector 450 has the function of detecting the temperature of the flue gas in the tower, which is used to control the temperature of the flue gas in the tower and ensure the dissolved waste gas in the water vapor entrained by the flue gas in the tower. The salt precipitates and crystallizes, and it is adjusted at 140℃-160℃ according to practical experience. Subsequently, the heated flue gas enters the purified flue gas conditioning tower 600 through the flange interface along the pipeline in the tower. The purified flue gas conditioning tower 600 is provided with a cooling device 620. When the heated flue gas passes through the cooling device 620, the inlet pipeline is connected to a condenser. The heat exchange tube bundle of the water cooling device 620 conducts heat exchange with the heating flue gas in the pipeline, the condensed water in the heat exchange tube bundle is heated and discharged from the heat exchange tube bundle of the cooling device 620, and the heated flue gas continues to rise along the pipeline. The fourth temperature detector 630 is used to control the temperature of the flue gas in the tower and the circulating water volume of the condensed water in the cooling device 620. According to practical experience, it is adjusted at 60°C-80°C. The heating flue gas passes heat exchange during the rising process, and the condensation of condensation The water falls into the condensed and recycled water collection device 610 located at the bottom of the purification flue gas conditioning tower 600, and the collected condensed and recycled water is returned to the circulating washing pool 100 through the pipeline to continue to be used for flue gas washing; and the rising heating flue gas reaches the standard after cooling. It can not only reduce energy consumption, effectively use circulating washing water, but also ensure the temperature of flue gas discharge, eliminate white smoke plumes, and improve environmental perception.

The structure and configuration of the second reheat evaporation tower 500 are the same as those of the first reheat evaporation tower 400. At this time, it is in a desalination state or a closed state. The second electric flue gas cut-off valve C510, the second electric flue gas cut-off valve B590 and the The second electric flue gas cut-off valve A570 is in the closed state. When desalting, the blind plate 520 of the second desalting part is opened and put into the second desalting insert plate 521. The second primary effect reheat evaporator 530 and the second secondary effect The reheat evaporator 540 is filled with high-temperature steam, and the waste salt attached to the outer wall of the heat exchange tube bundle is easy to melt and fall off after being heated at a high temperature. Temperature detector 560 is used to detect differential pressure and temperature in the tower. The second electric flue gas cut-off valve A570 is in the open position, and the salt cleaning fan 580 is turned on to let in the drying air to clean the salt. When the second differential pressure detector 550 shows that the pressure difference between the two detection positions is less than 100Pa, it is determined that the salt cleaning is completed. Close the second electric flue gas cut-off valve A570 and the second salt cleaning fan 580, take out the second demineralization insert 521 to collect waste salt and outsource the treatment; restore the second demineralization unit 520 to the working state, so far the second The reheat evaporation tower 500 completes the salt cleaning work and enters the quasi-working state, and the second electric flue gas cut-off valve C510 and the second electric flue gas cut-off valve B590 can be opened at any time to enter the working state. The first reheat evaporating tower 400 and the second reheat evaporating tower 500 are cyclically replaced in this way to form a flue gas reheating system for on-line desalination.

The method that utilizes the system of the present invention to work specifically comprises the following steps:

S01, as shown in FIG. 2, close the second electric flue gas shut-off valve C510, the second electric flue gas shut-off valve B590, the first electric flue gas shut-off valve A470 and the first salt cleaning fan 480, and open the first electric flue gas The cut-off valve C410 and the first electric flue gas cut-off valve B490 make the first reheat evaporation tower 400 in the working state, and the circulating water in the circulating washing pool 100 is sprayed into the wet washing tower 300 to complete the wet washing of the incineration flue gas , the temperature of the scrubbing flue gas is controlled between 100°C and 110°C;

S02, the circulating washing water falls into the circulating washing pool 100, and the pH is adjusted to weakly alkaline by adding lye. At the same time, the circulating water in the pool is pumped to the filter device 200 by the water pump for filtering, and the particulate matter and impurities are filtered, and the circulating washing pool is obtained. of high-salt wastewater;

S03, the washed flue gas enters the first reheating evaporation tower 400, completes the heating and evaporation of flue gas and the crystallization of waste salt through the first primary effect reheating evaporator 430 and the first second effect reheating evaporator 440, and enters the purification flue gas conditioning tower 600, the temperature of the heating flue gas is controlled between 140℃-160℃;

S04, the heated flue gas is passed through the cooling device 620 in the purification flue gas conditioning tower 600 to complete the cooling and condensation of the flue gas, and the temperature of the cooled flue gas is controlled between 60°C and 80°C, and is discharged up to the standard through the straight exhaust flue 700;

The condensed water produced by cooling in S05 and S04 falls into the condensed and recycled water collection device 610 located at the bottom of the purification flue gas conditioning tower 600, and flows to the circulating washing pool 100 for reuse through the pipeline; when the pressure difference in the first reheating evaporation tower 400 When the detector 450 detects and shows that the pressure difference is greater than 1000Pa, it is determined that the desalination requirement is met;

S06: As shown in FIG. 3, the first reheat evaporation tower 400 enters the demineralization state, and the second demineralization insert 521 is taken out to close the second demineralization unit 520, the second primary effect reheat evaporator 530 and the second Corresponding steam is introduced into the second-effect reheat evaporator 540, the second electric flue gas shut-off valve C510, the second electric flue gas shut-off valve B590, the first electric flue gas shut-off valve A470 are opened, and the first electric flue gas shut-off valve C410 is closed. , the first electric flue gas cut-off valve B490, the second electric flue gas cut-off valve A570, the incineration flue gas that has completed the wet washing enters the second reheat evaporation tower 500, and reproduces S01-S05 in the second reheat evaporation tower 500 ;

S07: After natural cooling, after the first temperature detector 460 shows that the temperature is lowered, open the first demineralization unit 420, put in the first demineralization insert 421, the first primary reheating evaporator 430 and the first secondary effect reheating Steam is introduced into the thermal evaporator 440, and the first demineralization fan 480 is activated to introduce hot dry air to demineralize the first reheat evaporation tower 400. When the first pressure difference detector 450 in the first reheat evaporation tower 400 When the detection shows that the pressure difference is less than 100Pa, it is determined that the desalination is completed;

S08: Turn off the first desalination fan 480 and the first electric flue gas cut-off valve A470, and cut off the steam in the first primary-effect reheat evaporator 430 and the first second-effect reheat evaporator 440;

S09: After natural cooling, after the first temperature detector 460 shows that the temperature has dropped, open the first demineralization unit 420, take out the demineralization insert 421, and immediately close the demineralization unit 420, collect and process the waste salt, and the first demineralization unit 420 is completed. Reheat evaporation tower 400 desalination work, enter the quasi-working state;

S10: When the second reheat evaporation tower 500 shows that it has reached the desalting state, repeat S06-S09 according to the same principle for the second reheat evaporation tower 500, and the first reheat evaporation tower 400 and the second reheat evaporation tower 500 are cyclically replaced in this way operation to realize flue gas reheating for on-line desalination.

The pressure difference and temperature range involved in this system are only practical data for a 20000m ³ /h hazardous waste incineration system.

The description and application of the present invention herein is illustrative, and is not intended to limit the scope of the present invention to the above-described embodiments. Variations and modifications to the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments are known to those of ordinary skill in the art. It should be apparent to those skilled in the art that the present invention may be implemented in other forms, structures, arrangements, proportions, and with other components, materials and components without departing from the spirit or essential characteristics of the invention. Other modifications and changes of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.

Claims (10)

1. A flue gas reheating system with on-line desalination function, characterized in that it comprises a circulating washing pool (100), a wet scrubbing tower (300) arranged above the circulating washing pool (100), a lower end and a wet scrubbing tower (300). The first reheat evaporation tower (400) and the second reheat evaporation tower (500) communicated with the washing tower (300), and the first reheat evaporation tower (400) and the upper end of the second reheat evaporation tower (500) are connected The purification flue gas conditioning tower (600) and the straight exhaust flue (700) arranged above the purification flue gas conditioning tower (600) are provided with a combustion flue gas inlet on the lower side of the wet scrubbing tower (300). 2 . The flue gas reheating system with on-line desalination function according to claim 1 , wherein a filter device ( 200 ) is connected to the circulating washing pool ( 100 ) through a pipeline. 3 . 3. A flue gas reheating system with on-line desalination function according to claim 1, characterized in that the first reheating evaporation tower (400) comprises first electric cigarettes arranged in sequence along the flue gas flow direction Gas shut-off valve C (410), first demineralizing unit (420), first heating device, first differential pressure detector (450), first temperature detector (460), first salt cleaning fan (480) and a first electric flue gas cut-off valve B (490), a first electric flue gas cut-off valve A (470) is provided on the air inlet pipeline of the first salt cleaning fan (480). 4. A flue gas reheating system with on-line desalination function according to claim 1 or 3, characterized in that the second reheating evaporation tower (500) comprises a second reheating tower (500) arranged in sequence along the flue gas flow direction Electric flue gas cut-off valve C (510), second demineralization unit (520), second heating device, second differential pressure detector (550), second temperature detector (560), second salt cleaning fan ( 580) and a second electric flue gas shut-off valve B (590), a second electric flue gas shut-off valve A (570) is provided on the air inlet pipeline of the second salt cleaning fan (580). 5 . The flue gas reheating system with on-line desalination function according to claim 1 , wherein a third temperature detector ( 310 ) is provided on the upper part of the wet scrubber ( 300 ). 6 . 6. A flue gas reheating system with on-line desalination function according to claim 3, characterized in that the first heating device comprises a first primary effect reheating evaporator ( 430) and a first second effect reheat evaporator (440). 7. A flue gas reheating system with on-line desalination function according to claim 4, characterized in that the second heating device comprises a second primary effect reheating evaporator ( 530) and a second second effect reheat evaporator (540). 8. A flue gas reheating system with on-line desalination function according to claim 1, characterized in that the purification flue gas conditioning tower (600) comprises a condensing and recycling water collection device (610), a cooling device (620) ) and a fourth temperature detector (630), the condensation recycling water collection device (610) is located below the cooling device (620) and communicated with the circulating washing pool (100), and the fourth temperature detector (630) is located in the cooling device (620) above. 9. A flue gas reheating system with on-line desalination function according to claim 2, characterized in that the filter device (200) is an activated carbon filter tank, and a tank inlet pipeline of the activated carbon filter tank is provided with a filter. pressure pump. 10. A flue gas reheating method with on-line desalination function, characterized in that it comprises the steps: Step 1. Close the second electric flue gas shut-off valve C (510), the second electric flue gas shut-off valve B (590), the first electric flue gas shut-off valve A (470) and the first salt cleaning fan (480), and turn on the The first electric flue gas cut-off valve C (410) and the first electric flue gas cut-off valve B (490) make the first reheat evaporation tower (400) in the working state, and the circulating water in the circulating washing pool (100) is sprayed into the wet scrubbing tower (300) to complete the wet scrubbing of the incineration flue gas; Step 2: The circulating washing water falls into the circulating washing pool (100), and the pH is adjusted to weakly alkaline by adding lye. At the same time, the circulating water in the pool is pumped to the filter device (200) by the water pump for filtration, and the particulate matter and impurities are filtered. It is necessary to circulate the high-salt wastewater in the washing pool; Step 3. The washed flue gas enters the first reheat evaporation tower (400), and the first primary effect reheat evaporator (430) and the first second effect reheat evaporator (440) complete the heating and evaporation of flue gas and the crystallization of waste salt , enter the purification flue gas adjustment tower (600); Step 4. The heated flue gas is passed through the cooling device (620) in the purification flue gas conditioning tower (600) to complete the cooling and condensation of the flue gas, and is discharged up to the standard through the straight exhaust flue (700); The condensed water generated in step 5 and step 4 falls into the condensed and reused water collection device (610) disposed at the bottom of the purification flue gas conditioning tower (600), and flows to the circulating washing pool (100) for reuse through the pipeline; When the pressure difference detector (450) in the reheat evaporation tower (400) detects and shows that the pressure difference is greater than 1000Pa, it is determined that the desalination requirement is met; Step 6: The first reheating evaporation tower (400) enters the demineralization state, and the second demineralization insert (521) is taken out to close the second demineralization unit (520), and the second primary reheating evaporator (530) and Corresponding steam is introduced into the second second-effect reheat evaporator (540), and the second electric flue gas shut-off valve C (510), the second electric flue gas shut-off valve B (590), and the first electric flue gas shut-off valve A are opened. (470), close the first electric flue gas shut-off valve C (410), the first electric flue gas shut-off valve B (490), and the second electric flue gas shut-off valve A (570), and the incineration flue gas after the wet scrubbing is completed enters The second reheat evaporation tower (500), repeat steps 1 to 5 in the second reheat evaporation tower (500); Step 7: After the first temperature detector (460) shows that the temperature is lowered, open the first demineralization unit (420), put in the first demineralization insert (421), and the first primary reheat evaporator (430) and Steam is introduced into the first and second-effect reheating evaporator (440), and the first demineralizing fan (480) is activated to introduce hot drying air to demineralize the first reheating evaporation tower (400). When the first pressure difference detector (450) in the evaporation tower (400) detects and shows that the pressure difference is less than 100Pa, it is determined that the desalination is completed; Step 8: Turn off the first desalination fan (480), the first electric flue gas cut-off valve A (470), and cut off the inside of the first primary effect reheat evaporator (430) and the first second effect reheat evaporator (440). of steam; Step 9: After cooling, after the first temperature detector (460) shows that the temperature has dropped, open the first demineralization unit (420), take out the demineralization insert (421), and immediately close the demineralization unit (420) to collect waste salt At this time, the first reheat evaporation tower (400) desalination work is completed, and the quasi-working state is entered; Step 10: When the second reheat evaporation tower (500) shows that it has reached the desalination state, repeat steps six to nine according to the same principle for the second reheat evaporation tower (500), the first reheat evaporation tower (400) and the The second reheating evaporation tower (500) operates in such a cyclic and replacement manner to realize the reheating of the flue gas for on-line desalination.

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