A treatment system and method for desulfurized wastewater

Abstract

The present invention discloses a treatment system and method for desulfurization wastewater in the field of wastewater treatment technology, including a desulfurization tower and a spray drying tower. A rotary atomizer is arranged in the spray drying tower, and a gas distributor is arranged below the rotary atomizer. The desulfurization wastewater generated by the desulfurization tower is transported to a triple box. The liquid outlet of the triple box is communicated with the liquid inlet of a wastewater pump. The liquid outlet of the wastewater pump is communicated with the spray drying tower through a pipeline. Hot flue gas is extracted from the main flue between the denitration reactor and the air preheater. The hot flue gas is purified by a high-temperature dust collector and then transported into the spray drying tower. The bottom of the spray drying tower is an outlet, and the dried inorganic salts are transported from the outlet to a salt recovery system; the structure of the present invention is simple, the operation is convenient, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a treatment system and method for desulfurization wastewater. Background Art

[0002] In order to meet the "Emission Standards for Air Pollutants from Thermal Power Plants" (GB13223-2011), the limestone-gypsum desulfurization process has become the standard configuration for coal-fired power plants. However, during the operation of this process, desulfurization wastewater containing various impurities will be generated, mainly including suspended solids, supersaturated sulfites, sulfates, and heavy metals, many of which are the first-class pollutants in the national environmental protection standards.

[0003] Currently, some power plants in China adopt the evaporation crystallization process to deeply treat desulfurization wastewater to meet the zero-discharge requirement, but the construction investment and operating costs of this process are relatively high. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and provide a treatment system and method for desulfurization wastewater, which is convenient to operate and has low cost.

[0005] The purpose of the present invention is achieved as follows: A treatment system for desulfurization wastewater includes a desulfurization tower and a spray drying tower. A gas distributor and a rotary atomizer are arranged in the spray drying tower. The desulfurization wastewater generated by the desulfurization tower is transported to a triple box. The liquid outlet of the triple box is communicated with the liquid inlet of a wastewater pump. The liquid outlet of the wastewater pump is communicated with the spray drying tower through a pipeline. Hot flue gas is extracted from the main flue between the denitration reactor and the air preheater. After being purified by a high-temperature dust collector, the hot flue gas is transported into the spray drying tower. The bottom of the spray drying tower is an outlet, and the dried inorganic salts are transported from the outlet to a salt recovery system.

[0006] In order to achieve the adjustability of the flue gas volume entering the spray drying tower, an inlet damper door that can adjust the flue gas volume entering the spray drying tower according to the flue gas temperature is arranged at the inlet of the spray drying tower, and the inlet damper door is an electric adjustment type damper door.

[0007] In order to further purify the flue gas discharged from the spray drying tower, an air outlet is opened on the side of the spray drying tower. The air outlet is located at the lower part of the spray drying tower and is communicated with an electrostatic precipitator. After the particulate soot in the flue gas is removed by the electrostatic precipitator, the flue gas is introduced into the desulfurization tower through a induced draft fan, and the flue gas desulfurized by the desulfurization tower is introduced into a chimney.

[0008] In order to further purify the desulfurization wastewater, the liquid outlet of the triple box is communicated with a membrane filter, and the wastewater filtered by the membrane filter is transported into the wastewater pump.

[0009] To achieve the feeding of the spray drying tower, a high-level feeding tank is provided on the pipeline connecting the waste water pump and the spray drying tower, and the high-level feeding tank is arranged above the spray drying tower.

[0010] As a further improvement of the present invention, the high-temperature dust collector is a high-temperature granular bed filter dust collector, a high-temperature metal filter dust collector or a high-temperature ceramic filter dust collector.

[0011] A method for treating desulfurized waste water includes the following steps:

[0012] The desulfurized waste water generated during the wet desulfurization process is passed through a triple box to precipitate heavy metals in the waste water. The desulfurized waste water output from the triple box is passed through a membrane filter to remove suspended solids, achieving solid-liquid separation. The membrane filter outputs waste water, which is transported by a waste water pump to a high-level feeding tank and flows into the spray drying tower by gravity. After being atomized by a rotary atomizer, it is sprayed downward;

[0013] Hot flue gas is extracted from the main flue between the denitration reactor and the air preheater. The extracted hot flue gas is first purified by a high-temperature dust collector. The purified hot flue gas with a temperature controlled at least at Tmin enters the spray drying tower through a gas distributor. Tmin is a set minimum temperature value. The hot flue gas comes into full contact with the atomized droplets. Moisture enters the flue gas, and the waste water quickly dries up. A part of the inorganic salts precipitated by evaporation falls into the discharge port at the bottom of the spray drying tower and is transported to the salt recovery system; another part of the fine inorganic salts enters the dust collector with the flue gas for treatment and capture. The treated flue gas is extracted by an induced draft fan and sent into the desulfurization tower for desulfurization, and the desulfurized flue gas is discharged through a chimney.

[0014] To achieve the controllability of treating desulfurized waste water, a control device is also used during the treatment of desulfurized waste water. The control device includes a controller and a temperature sensor I for detecting the inlet air temperature. The temperature sensor I is arranged in the pipeline between the spray drying tower and the high-temperature dust collector and is arranged corresponding to the inlet of the spray drying tower; a temperature sensor II for detecting the outlet air temperature is provided at the outlet of the lower part of the spray drying tower. A liquid flow meter for detecting the waste water flow rate into the spray drying tower is provided on the pipeline between the spray drying tower and the high-level feeding tank. A flow regulating valve for adjusting the waste water flow rate is provided on the pipeline between the liquid flow meter and the high-level feeding tank. A gas flow meter is provided on the flue between the high-temperature dust collector and the spray drying tower; the purified hot flue gas with a temperature not lower than Tmin enters the spray drying tower through a gas distributor. The specific control method is that when the temperature detected by the temperature sensor I is lower than Tmin, the control inlet baffle door is completely closed.

[0015] To further improve the evaporation efficiency and reduce the evaporation energy consumption, when introducing the hot flue gas, the following steps are also included:

[0016] (a1) The liquid flow meter sends the detected flow signal to the controller. The controller calculates the mass of the wastewater entering the spray drying tower based on the received wastewater flow rate. The controller records the time point t when the wastewater starts to be introduced. s0 ;

[0017] (a2) The gas flow meter sends the detected gas flow signal to the controller. The controller calculates the amount of flue gas entering the spray drying tower based on the received gas flow signal and the opening and closing degree of the inlet damper door, and records the time point t0 when the flue gas starts to be introduced;

[0018] (a3) The controller is based on the time point t s0 The order of introducing flue gas and wastewater can be determined by t0. If wastewater is introduced first, the time when △t0= t0-t s0 The mass of wastewater that has entered the spray drying tower within the time m △t0 The controller is based on the wastewater mass m st The opening and closing degree of the inlet damper door is adjusted according to the detected flue gas temperature to control the flue gas volume, so that the atomized droplets evaporate quickly; Among them, the relationship between the wastewater quality and the flue gas volume entering the spray drying tower is determined as follows: the energy Q required to evaporate the wastewater in time t st The calculation formula is as follows,

[0019] Q st =1000m st [r w +(T0-T1)c w ] (1);

[0020] Heat released by flue gas Q 气 The calculation formula is as follows,

[0021] Q 气 =c 气 m 气 △T 气 (2);

[0022] △T 气 =T 入 -T 出 (3);

[0023] From formula (1) to formula (3), the relationship between flue gas volume and water volume can be calculated as follows:

[0024] V 气 =1000m st [r w +(T1-T)c w ] / [c 气 *ρ 气 *(T 入 -T 出)] (4);

[0025] Wherein, m st is the mass of wastewater introduced into the spray drying tower within time t, r w is the latent heat of vaporization of water, c w is the specific heat capacity of water, T0 is the original temperature of the wastewater, T1 is the temperature of the steam after evaporation, c 气 is the specific heat capacity of the flue gas, T 入 is the inlet temperature of the flue gas, T 出 is the outlet temperature of the flue gas, ρ 气 is the density of the flue gas; T 入 is measured by temperature sensor one, T 出 is detected by temperature sensor two, m st = m △t0 +m t , m △t0 is the mass of wastewater that has been introduced into the spray drying tower before introducing the flue gas, m t is the mass of wastewater introduced into the spray drying tower during the time period from time point t0 to t;

[0026] The controller controls the opening degree of the intake baffle and the opening degree of the flow regulating valve according to the detected flue gas temperature and wastewater flow rate, so that within the set t1 time, the amount of flue gas introduced and m st1 meet the relational expression (4);

[0027] After the t1 time point, the amount of flue gas required to be introduced is calculated according to the relational expression (4) based on the mass of wastewater introduced in real time, and the opening degree of the inlet baffle is controlled to adjust the amount of flue gas introduced into the spray drying tower;

[0028] If hot flue gas is introduced first, calculate the amount of flue gas introduced into the spray drying tower within △t0 = t s0 - t0 time, and set it as V △t0 , the controller controls the opening degree of the intake baffle and the opening degree of the flow regulating valve according to the detected flue gas temperature and the amount of flue gas already introduced into the tower, so that within the set t2 time, V 气t2 and m st2 meet the relational expression (4), V 气t2 = V △t0 +V t2-ts0 , V t2-ts0 is the amount of flue gas introduced into the spray drying tower during the time period from t s0 to t2;

[0029] After the t2 time point, the amount of flue gas required to be introduced is calculated according to the relational expression (4) based on the mass of wastewater introduced in real time, and the opening degree of the inlet baffle is controlled to adjust the amount of flue gas introduced into the spray drying tower;

[0030] (a4) Determine whether the flow rate detected by the liquid flowmeter is 0. When the flow rate detected by the liquid flowmeter is 0, record the current time point as t3, and when the liquid flow rate remains 0 for the set time threshold t max , the controller confirms that there is no desulfurized wastewater flowing into the spray drying tower, and sets the total mass of wastewater obtained by cumulative calculation of the controller to m 总 , from m 总 calculate the total flue gas volume V that needs to be introduced into the spray drying tower 总 , judge the time period from t s0 to t3, whether the introduced flue gas volume V t3 exceeds V 总 , if V t3 < V 总 , within the set time t max , control the opening degree of the inlet damper to continue introducing flue gas into the spray drying tower to make V t3 = V 总 , at this time, control the inlet damper to close; otherwise, directly control the opening degree of the inlet damper to 0, and the desulfurized wastewater treatment is completed; if the flow rate detected by the liquid flowmeter is greater than 0, return to step (a3); through steps (a1) - (a4), according to the relationship between the flue gas volume and the wastewater quality, perform adaptive matching, with a quantitative wastewater corresponding to a quantitative flue gas volume, improve the controllability of the hot flue gas extracted from the flue between the air preheater and the denitration reactor, reduce energy consumption, and improve the evaporation efficiency. Description of the Drawings

[0031] Figure 1 It is a schematic structural connection diagram of the treatment system in the present invention.

[0032] Figure 2 It is a schematic structural connection block diagram of the control device in the present invention.

[0033] Among them, 1 is a triple box, 2 is a membrane filter, 3 is a wastewater pump, 4 is an outlet damper, 5 is an air preheater, 6 is an industrial boiler, 7 is a denitration reactor, 8 is a high-temperature dust collector, 9 is a gas distributor, 10 is a rotary atomizer, 11 is a high-level feed tank, 12 is an electrostatic precipitator, 13 is an induced draft fan, 14 is a desulfurization tower, 15 is a chimney, and 16 is a spray drying tower. Detailed Embodiments

[0034] The present invention will be further described below with reference to the drawings.

[0035] Such as Figure 1A desulfurized wastewater treatment system shown in the figure includes a desulfurization tower and a spray drying tower. A gas distributor and a rotary atomizer are arranged in the spray drying tower. The desulfurized wastewater generated by the desulfurization tower is transported to a triple box, which includes a neutralization box, a sedimentation box, and a flocculation box that are connected in sequence. The liquid outlet of the triple box is connected to a membrane filter. The wastewater filtered by the membrane filter is transported into a wastewater pump. A high-level feed box is provided on the pipeline connecting the wastewater pump and the spray drying tower. The liquid outlet of the wastewater pump is connected to the high-level feed box through a pipeline. The high-level feed box is arranged above the spray drying tower. Air is continuously introduced into the air preheater, and hot air is output from the air outlet of the air preheater. The output hot air is introduced into an industrial boiler. The hot flue gas generated by the industrial boiler is output from a denitration reactor. The hot flue gas is extracted from the main flue between the denitration reactor and the air preheater. The hot flue gas is purified by a high-temperature dust collector and then transported into the spray drying tower. The bottom of the spray drying tower is an outlet, and the dried inorganic salts are transported from the outlet to a salt recovery system.

[0036] In order to achieve the adjustability of the flue gas volume introduced into the spray drying tower, an inlet damper door that can adjust the flue gas volume entering the spray drying tower according to the flue gas temperature is provided at the inlet of the spray drying tower. The inlet damper door is an electric adjustment type damper door.

[0037] In order to further purify the flue gas discharged from the spray drying tower, an air outlet is opened on the side of the spray drying tower. The air outlet is located at the lower part of the spray drying tower. The air outlet is connected to an electrostatic precipitator. After the particulate soot in the flue gas is removed by the electrostatic precipitator, it is introduced into the desulfurization tower through a induced draft fan. The flue gas desulfurized by the desulfurization tower is introduced into a chimney.

[0038] In this embodiment, the high-temperature dust collector is a high-temperature ceramic filter dust collector.

[0039] In this embodiment, the pipeline connected to the flue gas outlet of the air preheater is bypass one, and the pipeline connected to the air outlet of the spray drying tower is bypass two. Bypass one and bypass two are aggregated into a main pipeline through an outlet damper door. The outlet damper door is an electric switch type valve.

[0040] A method for treating desulfurized wastewater using a desulfurized wastewater treatment system includes the following steps:

[0041] During the wet desulfurization process, the desulfurized wastewater generated precipitates heavy metals in the wastewater through a triple box. The desulfurized wastewater output from the triple box passes through a membrane filter to remove suspended solids, achieving solid-liquid separation. The membrane filter outputs wastewater, which is transported to a high-level feed box by a wastewater pump and flows into the spray drying tower by gravity. After being atomized by a rotary atomizer, it sprays downward;

[0042] Hot flue gas is extracted from the main flue between the denitration reactor and the air preheater. The extracted hot flue gas is first purified by a high-temperature dust collector. The purified hot flue gas with a temperature controlled between Tmin and Tmax enters the spray drying tower through a gas distributor. Tmin is the set minimum temperature value. If the flue gas temperature is lower than 240°C, the heat of the flue gas cannot ensure complete evaporation of the wastewater in the drying tower, and there is a risk of scaling on the inner wall of the drying tower. Therefore, Tmin is taken as 240°C to ensure complete evaporation of the wastewater by the flue gas. Tmax is the set maximum temperature value. Since the flue gas temperature at full load of the boiler does not exceed 380°C, Tmax is taken as 380°C. The hot flue gas comes into full contact with the atomized droplets, moisture enters the flue gas, and the wastewater quickly evaporates and dries. A part of the inorganic salts precipitated by evaporation falls into the discharge port at the bottom of the spray drying tower and is transported to the salt recovery system; another part of the fine inorganic salts enters the dust collector with the flue gas for treatment and capture. The treated flue gas is extracted by an induced draft fan into the desulfurization tower for desulfurization, and the desulfurized flue gas is discharged through the chimney.

[0043] To achieve the controllability of treating desulfurization wastewater, the control device (as shown in Figure 2 ) used for treating desulfurization wastewater includes a controller and a temperature sensor I for detecting the inlet temperature. The temperature sensor I is arranged in the pipeline between the spray drying tower and the high-temperature dust collector, and is arranged corresponding to the inlet of the spray drying tower; a temperature sensor II for detecting the outlet temperature is arranged at the outlet of the lower part of the spray drying tower, a liquid flowmeter for detecting the wastewater flow rate entering the spray drying tower is arranged on the pipeline between the spray drying tower and the high-level feed tank, a flow regulating valve for adjusting the wastewater flow rate is arranged on the pipeline between the liquid flowmeter and the high-level feed tank, and a gas flowmeter is arranged on the flue between the high-temperature dust collector and the spray drying tower; the purified hot flue gas with a temperature not lower than Tmin enters the spray drying tower through the gas distributor. The specific control method is that when the temperature detected by the temperature sensor I is lower than Tmin, the control inlet damper is completely closed.

[0044] To further improve the evaporation efficiency and reduce the evaporation energy consumption, when the hot flue gas purified by the high-temperature dust collector enters the spray drying tower, the following steps are included:

[0045] (a1) The liquid flowmeter sends the detected flow signal to the controller. The controller calculates the mass of the wastewater entering the spray drying tower according to the received wastewater flow rate, and the controller records the time point t when the wastewater starts to be introduced. s0 ;

[0046] (a2) The gas flowmeter sends the detected gas flow signal to the controller. The controller calculates the amount of flue gas entering the spray drying tower according to the received gas flow signal and the opening degree of the inlet damper, and records the time point t0 when the flue gas starts to be introduced.

[0047] The (a3) controller determines the sequence of introducing flue gas and wastewater based on time points t s0 and t0. If wastewater is introduced first, the mass m of wastewater that has been introduced into the spray drying tower within △t0 = t0 - t s0 time is calculated. The controller adjusts the opening degree of the inlet damper to control the flue gas volume according to the mass m of the introduced wastewater △t0 and the detected flue gas temperature, so that the atomized droplets evaporate quickly; among them, the relationship between the wastewater mass and the flue gas volume introduced into the spray drying tower is specifically that within t time, the energy Q required to evaporate the wastewater st is calculated as follows, st The calculation formula is as follows,

[0048] Q st = 1000m st [r w +(T0 - T1)c w (1);

[0049] The heat released by the flue gas Q 气 is calculated as follows,

[0050] Q 气 = c 气 m 气 △T 气 (2);

[0051] △T 气 = T 入 - T 出 (3);

[0052] From formula (1) to formula (3), the relationship between the flue gas volume and the water volume can be calculated as follows

[0053] V 气 = 1000m st [r w +(T1 - T)c w / [c 气 * ρ 气 * (T 入 - T 出 )] (4);

[0054] Among them, m st is the mass of wastewater introduced into the spray drying tower within t time, r w is the latent heat of vaporization of water, c w is the specific heat capacity of water, T0 is the original temperature of the wastewater, T1 is the temperature of the evaporated steam, c 气 is the specific heat capacity of the flue gas, T 入 is the inlet temperature of the flue gas, T 出 is the outlet temperature of the flue gas, ρ气 is the flue gas density; T 入 is measured by temperature sensor 1, T 出 is detected by temperature sensor 2, m st = m △t0 +m t , m △t0 is the mass of wastewater that has been introduced into the spray drying tower before the flue gas is introduced, m t is the mass of wastewater introduced into the spray drying tower during the time period from time point t0 to t;

[0055] The controller controls the opening degree of the intake baffle and the opening degree of the flow regulating valve according to the detected flue gas temperature and wastewater flow rate, so that within the set t1 time, the amount of flue gas introduced is in line with m st1 and conforms to relation (4);

[0056] After the t1 time point, calculate the amount of flue gas that needs to be introduced according to relation (4) based on the mass of wastewater introduced in real time, and control the opening degree of the inlet baffle to adjust the amount of flue gas introduced into the spray drying tower;

[0057] If hot flue gas is introduced first, calculate the amount of flue gas introduced into the spray drying tower within △t0 = t s0 - t0 time, and set it as V △t0 , the controller controls the opening degree of the intake baffle and the opening degree of the flow regulating valve according to the detected flue gas temperature and the amount of flue gas already introduced into the tower, so that within the set t2 time, V 气t2 is in line with m st2 and conforms to relation (4), V 气t2 = V △t0 +V t2-ts0 , V t2-ts0 is the amount of flue gas introduced into the spray drying tower during the time period from t s0 to t2;

[0058] After the t2 time point, calculate the amount of flue gas that needs to be introduced according to relation (4) based on the mass of wastewater introduced in real time, and control the opening degree of the inlet baffle to adjust the amount of flue gas introduced into the spray drying tower;

[0059] (a4) Judge whether the flow rate detected by the liquid flowmeter is 0. When the flow rate detected by the liquid flowmeter is 0, record the current time point as t3, and when the liquid flow rate remains 0 until the set time threshold t max , the controller confirms that there is no desulfurized wastewater introduced into the spray drying tower, and sets the total mass of wastewater obtained by cumulative calculation of the controller as m 总 , and calculate the total amount of flue gas V that needs to be introduced into the spray drying tower from m 总 , and judge the amount of flue gas V that has been introduced during the time period from t 总 to t3 s0 to t3t3 Whether it exceeds V 总 , if V t3 <V 总 , within the set time t max , control the opening and closing degree of the inlet baffle door to continue introducing flue gas into the spray drying tower, so that V t3 =V 总 . At this time, control the inlet baffle door to close; otherwise, directly control the opening and closing degree of the inlet baffle door to 0, and the desulfurized wastewater treatment is completed; if the flow rate detected by the liquid flowmeter is greater than 0, return to step (a3); through steps (a1)~(a4), adaptively match according to the relationship between the flue gas volume and the wastewater quality, with a quantitative amount of wastewater corresponding to a quantitative amount of flue gas volume, improve the controllability of the hot flue gas extracted from the flue between the air preheater and the denitration reactor, reduce energy consumption, and improve the evaporation efficiency.

[0060] In the present invention, the desulfurized wastewater generated from the desulfurization tower undergoes conditioning and precipitation in a triple box, and then the suspended solids are deeply removed by a membrane filter. Then, the desulfurized wastewater is transported to a high-level feed tank by a wastewater pump. Under the self-weight of the desulfurized wastewater, it flows into the rotary atomizer of the spray drying tower from the discharge port of the high-level feed tank. A stream of hot flue gas is extracted from the main flue between the SCR denitration reactor and the air preheater, first purified by a high-temperature dust collector and then enters the spray drying tower through a gas distributor. Among them, when introducing wastewater and hot flue gas into the spray drying tower, temperature sensor 1 detects the temperature of the hot flue gas entering the spray drying tower. The combined setting of temperature sensor 1 and the inlet baffle door ensures that the hot flue gas introduced into the spray drying tower is not lower than the set minimum temperature value Tmin, ensuring that the flue gas completely evaporates the wastewater; in addition, when introducing flue gas and desulfurized wastewater into the spray drying tower, by controlling the flue gas volume and desulfurized wastewater, specifically referring to steps (a1)~(a4), adaptively match according to the relationship between the flue gas volume and the wastewater quality, with a quantitative amount of wastewater corresponding to a quantitative amount of flue gas volume, improve the controllability of the hot flue gas extracted from the flue between the air preheater and the denitration reactor, reduce energy consumption, and improve the evaporation efficiency; the hot flue gas fully contacts the droplets of the desulfurized wastewater sprayed by the rotary atomizer, the wastewater quickly evaporates and dries, the moisture enters the flue gas, most of the inorganic salts evaporated and sucked out fall into the discharge port at the bottom of the drying tower, the inorganic salts enter the salt recovery system from the discharge port, and a small amount of fine inorganic salts flow into the subsequent electrostatic precipitator with the flue gas for treatment and capture to remove suspended particles. The treated flue gas is extracted by an induced draft fan and sent into the desulfurization tower for desulfurization, and the desulfurized flue gas is discharged through a chimney.

[0061] The structure of the present invention is simple and the operation is convenient. It utilizes the heat of the hot flue gas before the air preheater, without the need for additional steam, and has a low cost. After the desulfurized wastewater passes through the triple box and the membrane filter, the solid impurities such as suspended solids and metal ions in the wastewater are basically removed, which is beneficial to the evaporation of the desulfurized wastewater and can improve the salt content rate of the ash residue at the bottom of the drying tower. The dust-containing flue gas stream passes through the high-temperature dust collector, which preferentially removes the particulate matter in the flue gas and pre-removes the fly ash, improving the evaporation environment in the subsequent drying tower and avoiding the mixing of fly ash with the salt separated out by evaporation, which affects the resource utilization of fly ash. When introducing the flue gas and the desulfurized wastewater into the spray drying tower, by controlling the flue gas volume and the desulfurized wastewater, specifically referring to steps (a1) to (a4), an adaptive match is made according to the relationship between the flue gas volume and the wastewater quality. A certain amount of wastewater corresponds to a certain amount of flue gas volume, improving the controllability of the hot flue gas extracted from the flue between the air preheater and the denitration reactor, reducing energy consumption, and improving the evaporation efficiency. It can be applied to the work of recovering desulfurized wastewater.

[0062] The present invention is not limited to the above embodiments. The high-temperature dust collector can also be selected as a high-temperature particle bed filter dust collector or a high-temperature metal filter dust collector. Based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and deformations to some of the technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A treatment method for desulfurized wastewater. The treatment system used in the treatment includes a desulfurization tower and a spray drying tower. A rotary atomizer is arranged in the spray drying tower, and a gas distributor is arranged below the rotary atomizer. It is characterized in that, When treating desulfurized wastewater, a control device is also used. The control device includes a controller and a first temperature sensor for detecting the intake air temperature. The first temperature sensor is arranged in the pipeline between the spray drying tower and the high-temperature dust collector, and is arranged corresponding to the intake port of the spray drying tower; a second temperature sensor for detecting the outlet air temperature is arranged at the outlet of the lower part of the spray drying tower, a liquid flow meter for detecting the wastewater flow rate introduced into the spray drying tower is arranged on the pipeline between the spray drying tower and the high-level feed tank, a flow regulating valve for regulating the wastewater flow rate is arranged on the pipeline between the liquid flow meter and the high-level feed tank, and a gas flow meter is arranged on the flue between the high-temperature dust collector and the spray drying tower; the desulfurized wastewater generated by the desulfurization tower is transported to a triple box, the liquid outlet of the triple box is communicated with the liquid inlet of the wastewater pump, the liquid outlet of the wastewater pump is communicated with the spray drying tower through a pipeline, air is continuously introduced into the air preheater, hot air is output from the air outlet of the air preheater, the output hot air is introduced into the industrial boiler, the hot flue gas generated by the industrial boiler is output from the denitration reactor, hot flue gas is extracted from the main flue between the denitration reactor and the air preheater, the hot flue gas is purified by the high-temperature dust collector and then transported into the spray drying tower. The bottom of the spray drying tower is the discharge port, and the dried inorganic salts are transported from the discharge port to the salt recovery system. An inlet damper door that can adjust the amount of flue gas entering the spray drying tower according to the flue gas temperature is arranged at the inlet of the spray drying tower; the method includes the following steps: [[ID=,1]]During the wet desulfurization process, the desulfurized wastewater generated precipitates heavy metals in the wastewater through a triple box. The desulfurized wastewater output from the triple box passes through a membrane filter to remove suspended solids, realizing solid-liquid separation. The membrane filter outputs wastewater, and the wastewater is transported to the high-level feed tank by a wastewater pump and flows into the spray drying tower by gravity. After being atomized by a rotary atomizer, it sprays downward; Hot flue gas is extracted from the main flue between the denitration reactor and the air preheater. The extracted hot flue gas is first purified by the high-temperature dust collector. The purified hot flue gas with a temperature controlled at least at Tmin enters the spray drying tower through a gas distributor. Tmin is the set minimum temperature value. The hot flue gas fully contacts the atomized droplets, moisture enters the flue gas, the wastewater quickly dries up, and a part of the inorganic salts precipitated by evaporation falls into the discharge port at the bottom of the spray drying tower and is transported to the salt recovery system; another part of the fine inorganic salts enters the dust collector with the flue gas for treatment and capture. The treated flue gas is extracted by a induced draft fan and sent into the desulfurization tower for desulfurization, and the desulfurized flue gas is discharged through the chimney; When introducing hot flue gas, the following steps are further included: (a1) The liquid flowmeter sends the detected flow signal to the controller. The controller calculates the mass of the wastewater entering the spray drying tower based on the received wastewater flow rate, and the controller records the time point t when the wastewater starts to be introduced. s0 ; (a2)The gas flow meter sends the detected gas flow signal to the controller. The controller calculates the amount of flue gas entering the spray drying tower according to the received gas flow signal and the opening degree of the inlet damper door, and records the starting time point t0 of introducing the flue gas; (a3) The controller determines the sequence of introducing flue gas and wastewater according to the time points t s0 and t0. If wastewater is introduced first, calculate the mass m of wastewater that has been introduced into the spray drying tower within △t0 = t0 - t s0 during the time. The controller adjusts the opening degree of the inlet damper door according to the mass m of the introduced wastewater △t0 and the detected flue gas temperature to control the flue gas volume, so that the atomized droplets evaporate rapidly. Among them, determining the relationship between the wastewater mass and the flue gas volume introduced into the spray drying tower is specifically that within the time t, the energy Q required to evaporate the wastewater st is calculated as follows st The calculation formula is shown below Q st = 1000 m st [r w + (T0 - T1)c w (1); The heat released by the flue gas is Q 气 The calculation formula is as follows: Q 气 = c 气 m 气 △T 气 (2); △T 气 =T 入 -T 出 (3); The relationship between the amount of flue gas and the amount of water is calculated by formulas (1) to (3) as follows: V 气 = 1000 m st [r w + (T1 - T)c w / [c 气 * ρ 气 *(T 入 - T 出 )] (4); where m st is the mass of the wastewater introduced into the spray drying tower within time t, r w is the latent heat of vaporization of water, c w is the specific heat capacity of water, T0 is the original temperature of the wastewater, T1 is the temperature of the evaporated steam, c 气 is the specific heat capacity of the flue gas, T 入 is the inlet temperature of the flue gas, T 出 is the outlet temperature of the flue gas, ρ 气 is the density of the flue gas; T 入 is measured by temperature sensor 1, T 出 is detected by temperature sensor 2, m st = m △t0 + m t , m △t0 is the mass of the wastewater that has been introduced into the spray drying tower before the flue gas is introduced, m t is the mass of the wastewater introduced into the spray drying tower during the time period from time point t0 to t; The controller controls the opening degree of the intake baffle and the opening degree of the flow regulating valve according to the detected flue gas temperature and waste water flow rate, so that within the set time t1, the amount of flue gas introduced is in line with m st1 It conforms to the relational expression (4); After the time point t1, according to the mass of the wastewater introduced in real time, the amount of flue gas to be introduced is calculated according to the relational formula (4), and the opening degree of the inlet damper door is controlled to adjust the amount of flue gas entering the spray drying tower; If hot flue gas is introduced first, calculate △t0 = t s0 - the amount of flue gas introduced into the spray drying tower within the time of t0, which is set as V △t0 , the controller adjusts the opening degree of the intake baffle and the opening degree of the flow regulating valve according to the detected flue gas temperature and the amount of flue gas that has been introduced into the tower, so that within the set time t2, V 气t2 and m st2 meet the relational expression (4), V 气t2 = V △t0 +V t2-ts0 , V t2-ts0 is the amount of flue gas introduced into the spray drying tower during the period from t s0 to t2; After time point t2, the amount of flue gas to be introduced is calculated according to the mass of the waste water introduced in real time according to formula (4), and the opening degree of the inlet baffle door is controlled to adjust the amount of flue gas introduced into the spray drying tower; (a4) Determine whether the flow rate detected by the liquid flowmeter is 0. When the flow rate detected by the liquid flowmeter is 0, record the current time point as t3, and when the liquid flow rate remains 0 until the set time threshold t max the controller confirms that there is no desulfurized wastewater flowing into the spray drying tower, and sets the total mass of wastewater calculated by the controller's cumulative calculation to m 总 From m 总 calculate the total flue gas volume V that needs to be introduced into the spray drying tower 总 Judge during the time period from t s0 to t3 whether the introduced flue gas volume V t3 exceeds V 总 If V t3 < V 总 within the set time t max control the opening degree of the inlet damper to continue introducing flue gas into the spray drying tower to make V t3 = V 总 At this time, control the inlet damper to close; otherwise, directly control the opening degree of the inlet damper to 0, and the desulfurized wastewater treatment is completed; if the flow rate detected by the liquid flowmeter is greater than 0, return to step (a3).

2. The treatment method of desulfurized wastewater according to claim 1, characterized in that The inlet baffle door is an electrically adjustable baffle door.

3. The treatment method of desulfurized wastewater according to claim 1, characterized in that, An air outlet is provided on the side of the spray drying tower. The air outlet is located at the lower part of the spray drying tower. The air outlet is connected to an electrostatic precipitator. After the particulate soot in the flue gas is removed by the electrostatic precipitator, it is introduced into a desulfurization tower through a induced draft fan, and the flue gas desulfurized by the desulfurization tower is introduced into a chimney.

4. A method for treating desulfurized wastewater according to claim 1, characterized in that, The liquid outlet of the triple box is connected to a membrane filter, and the waste water filtered by the membrane filter is transported into a waste water pump.

5. A method for treating desulfurized wastewater according to any one of claims 1 to 4, characterized in that, A high-level feed box is provided on the pipeline connecting the waste water pump and the spray drying tower, and the high-level feed box is arranged above the spray drying tower.

6. The treatment method of desulfurized wastewater according to claim 5, characterized in that The high-temperature dust collector is a high-temperature granular bed filter dust collector, a high-temperature metal filter dust collector or a high-temperature ceramic filter dust collector.

7. A method for treating desulfurized wastewater according to any one of claims 1 to 4, characterized in that, The purified hot flue gas with a temperature not lower than Tmin enters the spray drying tower through a gas distributor. Specifically, the control method is that when the temperature detected by temperature sensor 1 is lower than Tmin, the inlet baffle door is controlled to be completely closed.

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