Petrochemical flue gas desulfurization wastewater zero discharge and resource treatment device system and method

Abstract

The invention provides a petrochemical flue gas desulfurization wastewater zero-discharge and resource treatment device system and a petrochemical flue gas desulfurization wastewater zero-discharge and resource treatment method. The petrochemical flue gas desulfurization wastewater zero-discharge and resource treatment device system comprises a primary pretreatment module, a deep pretreatment module and a concentration and crystallization module, the primary pretreatment module comprises a chemical adding and impurity removing unit, a coagulating sedimentation unit and an air floatation unit which are connected in sequence; the deep pretreatment module comprises a deep impurity removal unit, a deep COD (Chemical Oxygen Demand) removal unit and a deep hardness removal unit which are connected in sequence; the concentration and crystallization module comprises a membrane concentration unit, an acid adjusting and degassing unit, an evaporative crystallization unit, a liquid-solid separation unit and a mother liquor drying unit which are connected in sequence; the membrane concentration unit and the evaporative crystallization unit are both connected with a recycled water storage device. The method realizes high-efficiency recycling of water in the petrochemical flue gas desulfurization wastewater and high-value utilization of salt, and has a large-scale popularization and application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater treatment, and particularly to a zero-discharge and resource utilization disposal device system and method for flue gas desulfurization wastewater in petrochemical industry. Background Art

[0002] In the petrochemical industry, catalytic cracking is one of the core processes for lightening heavy oil in petroleum refining. It is a process in which the feedstock oil undergoes a cracking reaction after heating under the action of a catalyst to generate dry gas, liquid hydrocarbons, gasoline, diesel, slurry and coke. The generated coke adheres to the surface of the catalyst, and the catalyst is transported to the regenerator through a diagonal pipe for burning to restore the activity of the catalyst for recycling. The flue gas discharged from the regenerator is separated from a part of the catalyst by a cyclone, and then the waste heat is recovered by a waste heat boiler and discharged to the atmosphere through a chimney.

[0003] In the purification process of refinery catalytic flue gas, the wet desulfurization process is usually adopted in the desulfurization section, so a large amount of saline wastewater will be generated finally. At present, the sodium alkali method is mainly used for catalytic flue gas desulfurization treatment, and the main chemical reactions involved are:

[0004] SO2 + H2O → H2SO3

[0005] H2SO3 + 2NaOH → Na2SO3 + 2H2O

[0006] Na2SO3 + H2SO3 → 2NaHSO3

[0007] NaHSO3 + NaOH → Na2SO3 + H2O

[0008] Na2SO3 + 1 / 2O2 → Na2SO4

[0009] During the operation of the desulfurization device, saline wastewater with high COD, high suspended solids, high oil pollution and containing heavy metals will be discharged. The main components of the wastewater salt are sodium sulfate and sodium sulfite. The main sources of suspended solids and heavy metals are the fine catalyst powders in the flue gas, and the main sources of COD and oil pollution are the feedstock oil used in the catalytic cracking section and the high-molecular organic substances such as anti-gelling agents and activators added, as well as pseudo-COD such as sulfite and bisulfite.

[0010] Currently, all mature flue gas desulfurization processes are equipped with a supporting wastewater treatment unit PTU. That is, the slurry discharged from the bottom of the desulfurization scrubbing tower enters the clarifier and is mixed with the flocculant for solid-liquid separation. The sediment particles at the bottom are dehydrated through a filter box to form a cake, which is transported for external treatment. The supernatant of the clarifier enters a series of oxidation tanks, and sodium sulfite is converted into sodium sulfate by air oxidation to reduce the COD of the wastewater. After filtration through a filter to reduce the suspended solids in the wastewater, and finally cooled by a cooler to achieve up-to-standard discharge. However, during the actual operation of the device, there are often situations where pollutants such as wastewater COD and suspended solids do not meet the standards, increasing the environmental risk of wastewater discharge.

[0011] CN112390436A discloses a pretreatment method for catalytic cracking flue gas desulfurization wastewater. The desulfurization wastewater enters an ultrafiltration device, the ultrafiltration product water enters a nanofiltration device, the nanofiltration product water is incorporated into the sewage treatment plant, and the nanofiltration concentrate enters an evaporation crystallization device to finally obtain solid sodium sulfate salt and evaporation crystallization product water. This method uses the ultrafiltration device to remove suspended solids. Since most of the suspended solids are fine catalyst powders and the dust concentration is relatively high during the regular soot blowing stage, it is easy to cause the ultrafiltration membrane to operate overloaded, with serious membrane fouling, and the treatment efficiency is greatly reduced. In addition, the desulfurization wastewater contains COD and oil stains. After being treated by the nanofiltration device, the concentrate contains high-concentration COD and oil stains after enrichment. The quality of the product water and sodium sulfate salt obtained after being treated by the evaporation crystallization device cannot be guaranteed.

[0012] CN117550731A discloses a treatment method for catalytic cracking flue gas desulfurization wastewater. The desulfurization wastewater is treated through pretreatment, evaporation concentration, freeze crystallization, miscellaneous salt drying, and optional mirabilite resource utilization steps. After the desulfurization wastewater pretreatment unit is treated, it is first heated for evaporation crystallization and then cooled for freeze crystallization to obtain mirabilite. This process requires a large amount of heat energy and cold energy, with high operating energy consumption, and there is a large energy loss during the process of high-temperature evaporation to low-temperature freezing of the wastewater. [[ID=⑧]]

[0013] CN118993417A discloses a resource utilization treatment method for catalytic cracking flue gas desulfurization wastewater. The desulfurization wastewater includes steps such as aeration oxidation, carbon dioxide neutralization reaction, flocculation precipitation, evaporation concentration, metathesis reaction, concentration separation, centrifugal separation, evaporation in an ammonia stripping tower, evaporation and concentration in an evaporation kettle, and centrifugal separation. The aim is to prepare sodium bicarbonate that can be recycled for desulfurization through a metathesis reaction with sodium sulfate salt in the wastewater, with ammonium sulfate as a by-product. This method has a complex process and a long flow. The conversion rate of sodium bicarbonate is greatly affected by the impurity components in the wastewater, and the fluctuation of water quality conditions is likely to increase the difficulty of dosing operation control, and the resource utilization disposal effect is likely to be discounted.

[0014] In summary, for the wastewater from refining catalytic flue gas purification, there is an urgent need for a disposal method with a simple process, low operating energy and material consumption, which can simultaneously achieve high-efficiency reuse of wastewater moisture and high-value utilization of salts. Summary of the Invention

[0015] In view of the problems existing in the prior art, the present invention provides a zero-discharge and resource utilization disposal device system and method for petrochemical flue gas desulfurization wastewater. Through a primary pretreatment module, a deep pretreatment module and a concentration and crystallization module with specific compositions, impurities such as heavy metals, hardness, suspended solids, and COD in the petrochemical flue gas desulfurization wastewater are efficiently removed, water recovery is carried out, zero discharge of wastewater is achieved, and high-purity sodium sulfate by-product salt is obtained at the same time. The zero-discharge and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater of the present invention has a compact structure, stable and reliable operation, low operation energy consumption and material consumption, and a simple treatment process and strong water quality adaptability, realizing the resource utilization disposal of petrochemical flue gas desulfurization wastewater.

[0016] To achieve this purpose, the present invention adopts the following technical solutions:

[0017] In a first aspect, the present invention provides a zero-discharge and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater, and the zero-discharge and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater includes a primary pretreatment module, a deep pretreatment module and a concentration and crystallization module;

[0018] The primary pretreatment module includes a chemical addition and impurity removal unit, a coagulation and sedimentation unit and a flotation unit connected in sequence;

[0019] The deep pretreatment module includes a deep impurity removal unit, a deep COD removal unit and a deep hardness removal unit connected in sequence;

[0020] The concentration and crystallization module includes a membrane concentration unit, an acid adjustment and degassing unit, an evaporation and crystallization unit, a liquid-solid separation unit and a mother liquor drying unit connected in sequence; both the membrane concentration unit and the evaporation and crystallization unit are connected to a recovered water storage device.

[0021] The zero - discharge and resource - utilization disposal device system for petrochemical flue gas desulfurization wastewater described in the present invention is reasonably designed with low operation energy consumption and material consumption. The petrochemical flue gas desulfurization wastewater first enters the primary pretreatment module, and successively enters the chemical addition and impurity removal unit, coagulation sedimentation unit and air - flotation unit to achieve the preliminary removal of heavy metals, oil stains, suspended solids, COD and hardness in the wastewater. Then the wastewater enters the advanced pretreatment module, and successively enters the advanced impurity removal unit, advanced COD removal unit and advanced hardness removal unit to deeply remove the remaining heavy metals, oil stains, suspended solids, COD and hardness in the wastewater that are difficult to remove, avoiding adverse effects such as membrane fouling and heat exchanger scaling caused by enrichment in the subsequent concentration and crystallization module. Finally, the wastewater enters the concentration and crystallization module, and successively enters the membrane concentration unit, acid - adjustment and degassing unit, evaporation and crystallization unit, liquid - solid separation unit and mother - liquor drying unit to achieve water recovery, reaching zero - discharge of wastewater, and also recovering the salts in the wastewater to obtain high - purity sodium sulfate by - product salt. The device system in the present invention realizes the zero - discharge and resource - utilization disposal of petrochemical flue gas desulfurization wastewater, which is beneficial to pollution reduction, carbon emission reduction and synergistic efficiency improvement in the field of industrial wastewater treatment.

[0022] The advanced pretreatment module described in the present invention includes an advanced impurity removal unit, an advanced COD removal unit and an advanced hardness removal unit connected in sequence. The connection sequence of these units is crucial for the subsequent treatment effect of wastewater. It is beneficial to the removal of hardness in the wastewater that the wastewater first enters the advanced impurity removal unit and then enters the advanced COD removal unit. If the wastewater directly enters the advanced COD removal unit without entering the advanced impurity removal unit, the residual reducing sulfite in the wastewater will affect the degradation efficiency of COD in the advanced COD removal unit, resulting in an increase in the COD content in the treated wastewater, and further reducing the softening treatment effect of the subsequent advanced hardness removal unit, leading to an increase in the hardness value of the effluent from the softening resin bed. If the wastewater generated by the advanced impurity removal unit does not undergo advanced COD removal and directly enters the advanced hardness removal unit, the high COD content in the wastewater will greatly reduce the softening treatment effect of the advanced hardness removal unit, resulting in an increase in the effluent hardness value.

[0023] Preferably, both the coagulation sedimentation unit and the advanced impurity removal unit are connected to the sludge conveying device.

[0024] Preferably, the liquid - solid separation unit is connected to the sodium sulfate by - product salt storage device.

[0025] Preferably, the mother - liquor drying unit is connected to the miscellaneous salt conveying device.

[0026] [[ID=IS]]Preferably, the coagulation sedimentation unit includes any one or combination of a high - density sedimentation tank, a vertical - flow sedimentation tank or an inclined - plate sedimentation tank. Among them, typical but non - restrictive combinations include the combination of a high - density sedimentation tank and a vertical - flow sedimentation tank, the combination of an inclined - plate sedimentation tank and a high - density sedimentation tank, or the combination of a vertical - flow sedimentation tank and an inclined - plate sedimentation tank.

[0027] Preferably, a filter press dehydration device is further arranged between the coagulation sedimentation unit and the sludge conveying device.

[0028] Preferably, the air flotation unit includes a dissolved air flotation machine, which can effectively remove oil stains in the wastewater and can also cooperate to further remove suspended solids.

[0029] Preferably, the deep impurity removal unit includes a water inlet pipe, a filter membrane module, and a water production pipe connected in sequence, which deeply removes the suspended solids remaining in the wastewater and difficult to remove in the coagulation sedimentation unit and the air flotation unit, mainly the extremely fine catalyst powder with a very small particle size, and can also synchronously remove some organic impurities COD in the wastewater. At the same time, the sodium sulfite salt remaining in the wastewater is converted into sodium sulfate salt.

[0030] Preferably, an aeration device is arranged around the filter membrane module.

[0031] Preferably, the aeration device includes a blower, an air inlet pipe, and an aeration head connected in sequence.

[0032] In the present invention, the wastewater discharged from the air flotation unit is pumped into the deep impurity removal unit by the water inlet pipe. Through the action of the filter membrane module, the remaining suspended solids contained in the wastewater are intercepted on the outer surface of the membrane. Under the action of the water production pump, the filtrate is transported to the next unit through the water production pipe. The micro-sized air bubbles generated by the aeration head, on the one hand, conduct a full-range contact oxidation reaction with the wastewater to convert the sodium sulfite salt remaining in the wastewater into sodium sulfate salt, and on the other hand, are used to stir the liquid near the filter membrane module and the filter membrane body itself, playing an on-line continuous scrubbing and cleaning role for the filter membrane module, maintaining its high interception efficiency, increasing the service life of the filter membrane body, and extending the on-line rate of the unit device.

[0033] In the present invention, the cross-section of the air outlet hole of the aeration head is in the vertical direction and faces the filter membrane body, which is beneficial to better realizing the air scrubbing and decontamination effect on the outer surface of the membrane, and also avoids the blockage of the air outlet hole caused by the settlement of suspended solids.

[0034] Preferably, a sludge discharge pipe is arranged at the bottom of the deep impurity removal unit.

[0035] Preferably, the sludge discharge pipe is connected to the filter press dehydration device, and the suspension liquid at the bottom of the deep impurity removal unit is discharged through the sludge discharge pipe to the filter press dehydration device in the coagulation sedimentation unit for treatment.

[0036] Preferably, the filter membrane module includes a hollow fiber type ultrafiltration membrane and adopts negative pressure suction for water outlet.

[0037] Preferably, the position of the filter membrane module is more than 1 / 3 away from the bottom of the pool. For example, it can be 1 / 3, 2 / 5, 9 / 20, 3 / 5, 2 / 3, or 4 / 5, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0038] In the present invention, preferably, the position of the filter membrane module is more than 1 / 3 away from the bottom of the pool, so as to leave sufficient sedimentation height and space for suspended substances at the bottom of the pool.

[0039] Preferably, the advanced COD removal unit includes an advanced oxidation device and an activated carbon adsorption device connected in sequence. The advanced oxidation device can remove the components of organic matter that are difficult to degrade in the wastewater, and the activated carbon adsorption device removes the components of organic matter that are still difficult to degrade and remove after advanced oxidation, minimizing the adverse effects of the components of organic matter in the wastewater on the downstream process sections.

[0040] Preferably, the advanced oxidation device includes any one of an ozone catalytic oxidation device, an electrocatalytic oxidation device, or a photocatalytic oxidation device.

[0041] Preferably, the advanced hardness removal unit includes a softening resin bed, which can reduce the hardness of the wastewater to below 1 mg / L, reducing the risk of membrane fouling, heater fouling, and evaporator fouling in the downstream unit devices.

[0042] Preferably, the membrane concentration unit includes a high-pressure reverse osmosis membrane.

[0043] Preferably, the acid adjustment and degassing unit includes a degassing tower.

[0044] Preferably, the evaporation and crystallization unit includes a vertical tube falling film evaporator and a forced circulation crystallizer connected in sequence.

[0045] The vertical tube falling film evaporator described in the present invention has high heat transfer performance, and existing MVR (mechanical vapor recompression), TVR (thermal vapor recompression), and multi-effect evaporation crystallization can be adopted according to the application scenario. If the steam supply in the usage scenario is sufficient and inexpensive, the combined use of TVR and multi-effect evaporation crystallization can be considered preferentially; if the power supply in the usage scenario is sufficient and inexpensive, the combined use of MVR evaporation crystallization can be considered preferentially. The crystallizer can adopt a DTB crystallizer (draft tube baffled evaporative crystallizer) or an OLSO crystallizer (Oslo evaporative crystallizer) to obtain large and uniform crystal salt particles.

[0046] Preferably, the liquid-solid separation unit includes a thickener and a dehydration device connected in sequence.

[0047] Preferably, the dehydration device is also connected to a drying device, and the solid wet salt is dried by the drying device to obtain the final by-product sodium sulfate salt.

[0048] In the present invention, a part of the filtrate of the dehydration device returns to the forced circulation crystallizer for internal circulation, and the other part is pumped into the mother liquor drying unit.

[0049] Preferably, the mother liquor drying unit includes a drum dryer for dehydrating and drying a small amount of mother liquor to obtain miscellaneous salts for external transportation and disposal, which is used to regularly discharge the impurities enriched in the crystallization device, such as COD and non-sodium sulfate salts, so as to improve the purity and quality of the by-product sodium sulfate salt.

[0050] In a second aspect, the present invention also provides a method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater. The method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater is carried out by using the petrochemical flue gas desulfurization wastewater zero discharge and resource utilization device system described in the first aspect;

[0051] The method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater includes the following steps:

[0052] (1) The petrochemical flue gas desulfurization wastewater enters the primary pretreatment module. After removing hardness and heavy metals through the chemical addition and impurity removal unit, it enters the coagulation sedimentation unit and the air flotation unit to remove suspended solids and oil.

[0053] (2) The treated wastewater enters the deep pretreatment module, successively passes through the deep impurity removal unit to further remove suspended solids and some COD impurities and convert the residual sodium sulfite salt in the wastewater into sodium sulfate salt, enters the deep COD removal unit to remove refractory organic matter, and enters the deep hardness removal unit to reduce the hardness of the wastewater.

[0054] (3) The wastewater with reduced hardness enters the concentration and crystallization module. First, the inorganic salts in the wastewater are concentrated by the membrane concentration unit, then the CO2 and non-condensable gases in the wastewater are discharged through the acid adjustment and degassing unit, and then the inorganic salt ions in the wastewater are evaporated and concentrated to precipitate crystal salt particles to form a thick slurry through the evaporation crystallization unit. The thick slurry enters the liquid-solid separation unit for sedimentation enrichment and drying treatment to obtain the by-product sodium sulfate salt, realizing the resource utilization of the wastewater; the filtrate generated by the liquid-solid separation unit enters the mother liquor drying unit for dehydration and drying to obtain miscellaneous salts; the water produced by the membrane concentration unit is recycled, and the distillate generated by the evaporation crystallization unit is recycled, realizing the zero discharge of the wastewater.

[0055] The process flow of the method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater described in the present invention is simple and has low energy consumption. After the petrochemical flue gas desulfurization wastewater is treated in the primary pretreatment module and the deep pretreatment module, the wastewater only contains inorganic salt components and trace amounts of heavy metals, oil, suspended solids, COD and hardness; when it enters the concentration and crystallization module, after the inorganic salts in the wastewater are concentrated by the membrane concentration unit, the CO2 and non-condensable gases in the wastewater are discharged through the acid adjustment and degassing unit, reducing the corrosion effect of acidic gases and dissolved oxygen in the wastewater on the downstream process equipment and the influence on the heat transfer efficiency; in the concentration and crystallization module, the inorganic salt ions in the wastewater are concentrated and crystallized to obtain the by-product sodium sulfate salt, realizing the resource utilization of the wastewater; and the water produced by the membrane concentration unit and the distillate generated by the evaporation crystallization unit are recycled, realizing the zero discharge of the wastewater.

[0056] The water produced by the membrane concentration unit of the present invention can be reused in the in-plant circulating water field or the chemical water treatment unit.

[0057] Preferably, the sludge generated by the coagulation sedimentation unit and the deep impurity removal unit enters the sludge conveying device.

[0058] Preferably, the by-product sodium sulfate salt obtained by the liquid-solid separation unit enters the by-product sodium sulfate salt storage device.

[0059] Preferably, the miscellaneous salt obtained by the mother liquor drying unit enters the miscellaneous salt conveying device.

[0060] Preferably, a first precipitant is added to the chemical addition and impurity removal unit.

[0061] Preferably, the first precipitant includes sulfide or alkali solution.

[0062] Preferably, the dosage of the first precipitant is 1.05 - 1.1 times the theoretically required dosage for heavy metal removal. For example, it can be 1.05 times, 1.055 times, 1.06 times, 1.065 times, 1.07 times, 1.09 times, or 1.1 times, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0063] Preferably, a second precipitant is also added to the chemical addition and impurity removal unit.

[0064] Preferably, the second precipitant includes sodium hydroxide or sodium carbonate.

[0065] Preferably, the dosage of the second precipitant is 1.05 - 1.1 times the theoretically required dosage for hardness removal. For example, it can be 1.05 times, 1.055 times, 1.06 times, 1.065 times, 1.07 times, 1.09 times, or 1.1 times, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0066] Preferably, a coagulant and a flocculant are added to the coagulation sedimentation unit to remove the suspended catalyst fine powder with a particle size of 1 - 3 μm in the wastewater, and the removal efficiency of the wastewater suspended solids is improved through actions such as net capture and sweeping, adsorption and neutralization, and bridging.

[0067] Preferably, the coagulant includes polyferric sulfate, and the dosage is 10 - 100 mg / L. For example, it can be 10 mg / L, 20 mg / L, 30 mg / L, 50 mg / L, 70 mg / L, 90 mg / L, or 100 mg / L, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0068] Preferably, the flocculant comprises polyacrylamide, and the dosage is 1-10 mg / L. For example, it can be 10 mg / L, 20 mg / L, 30 mg / L, 50 mg / L, 70 mg / L, 90 mg / L or 100 mg / L, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0069] In the present invention, polyferric sulfate is used as the coagulant and polyacrylamide is used as the flocculant, which can effectively synergistically remove the phosphate brought into the wastewater by adding catalytic cracking additives.

[0070] Preferably, before the wastewater enters the degassing tower of the acid adjustment and degassing unit, acid is added to adjust the pH to 5-6. For example, it can be 5, 5.3, 5.5, 5.7, 5.9 or 6, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable;

[0071] Heat up to 90-95 °C. For example, it can be 90 °C, 90.5 °C, 91 °C, 91.5 °C, 92 °C, 93 °C or 95 °C, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0072] As a preferred technical solution of the present invention, the zero-discharge and resource utilization method for petrochemical flue gas desulfurization wastewater comprises the following steps:

[0073] (1) The petrochemical flue gas desulfurization wastewater enters the primary pretreatment module. After removing hardness and heavy metals through the chemical addition and impurity removal unit, it enters the coagulation sedimentation unit and the air flotation unit to remove suspended solids and oil;

[0074] A first precipitant is added in the chemical addition and impurity removal unit; the first precipitant comprises sulfide or alkali solution; the dosage of the first precipitant is 1.05-1.1 times the theoretically required dosage for removing heavy metals; a second precipitant is also added in the chemical addition and impurity removal unit; the second precipitant comprises sodium hydroxide or sodium carbonate; the dosage of the second precipitant is 1.05-1.1 times the theoretically required dosage for removing hardness;

[0075] (2) The treated wastewater enters the deep pretreatment module, and successively passes through the deep impurity removal unit to further remove suspended solids and some COD impurities and convert the residual sodium sulfite in the wastewater into sodium sulfate, enters the deep COD removal unit to remove refractory organic matter, and enters the deep hardness removal unit to reduce the hardness of the wastewater;

[0076] The sludge generated in the coagulation sedimentation unit and the deep impurity removal unit enters the sludge conveying device; a coagulant and a flocculant are added in the coagulation sedimentation unit; the coagulant comprises polyferric sulfate, and the dosage is 10-100 mg / L; the flocculant comprises polyacrylamide, and the dosage is 1-10 mg / L;

[0077] (3) The wastewater after hardness reduction enters the concentration and crystallization module, successively passes through the membrane concentration unit to concentrate the inorganic salts in the wastewater, enters the acid adjustment and degassing unit to discharge CO2 and non-condensable gases in the wastewater, enters the evaporation and crystallization unit to precipitate crystal salt particles from the inorganic salt ions in the wastewater through evaporation and concentration to form a thick slurry, enters the liquid-solid separation unit for sedimentation enrichment and drying treatment to obtain by-product sodium sulfate salt, realizing the resource utilization of wastewater; the filtrate generated by the liquid-solid separation unit enters the mother liquor drying unit for dehydration and drying to obtain miscellaneous salts; the water produced by the membrane concentration unit is recovered, and the distilled liquid generated by the evaporation and crystallization unit is recovered, realizing zero discharge of wastewater;

[0078] Before the wastewater enters the degassing tower of the acid adjustment and degassing unit, acid is added to adjust the pH to 5-6, and the temperature is heated to 90-95 °C; the by-product sodium sulfate salt obtained by the liquid-solid separation unit enters the by-product sodium sulfate salt storage device; the miscellaneous salts obtained by the mother liquor drying unit enter the miscellaneous salt conveying device.

[0079] Compared with the prior art, the present invention has at least the following beneficial effects:

[0080] The zero-discharge and resource utilization device system for petrochemical flue gas desulfurization wastewater provided by the present invention has a compact structure, stable and reliable operation, low operation energy consumption and material consumption. The zero-discharge and resource utilization method for petrochemical flue gas desulfurization wastewater has a simple process, strong water quality adaptability, realizes high-efficiency reuse of water in wastewater and high-value utilization of salts. The wastewater recovery rate can reach more than 98%, the miscellaneous salt rate is less than 5%, and the obtained by-product sodium sulfate has high quality, meeting the requirements of Class I products in the national standard "Industrial Anhydrous Sodium Sulfate" (GB / T 6009-2014), and can be sold as an auxiliary agent for printing and dyeing, papermaking, and glass manufacturing, effectively contributing to pollution reduction and carbon reduction, and synergistic efficiency improvement in the field of industrial wastewater treatment. Description of the Drawings

[0081] Figure 1 is a flow chart of the zero-discharge and resource utilization device system for petrochemical flue gas desulfurization wastewater in Embodiment 1 of the present invention.

[0082] Figure 2 is a front view of the deep impurity removal unit in Embodiment 1 of the present invention.

[0083] Figure 3 is a top view of the deep impurity removal unit in Embodiment 1 of the present invention. [[ID=?]]

[0084] In the figure: 1 - primary pretreatment module; 101 - dosing and impurity removal unit; 102 - coagulation and sedimentation unit; 103 - flotation unit;

[0085] 2 - Deep Pretreatment Module; 201 - Deep Impurity Removal Unit; 2011 - Water Inlet Pipe; 2012 - Sludge Drain Pipe; 2013 - Membrane Filter Block; 2014 - Aeration Head; 2015 - Product Water Pipe; 2016 - Air Inlet Pipe; 202 - Deep COD Removal Unit; 203 - Deep Hardness Removal Unit;

[0086] 3 - Concentration and Crystallization Module; 301 - Membrane Concentration Unit; 302 - Acid Adjustment and Degassing Unit; 303 - Evaporation and Crystallization Unit; 304 - Liquid - Solid Separation Unit; 305 - Mother Liquid Drying Unit. Detailed Embodiment

[0087] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments.

[0088] The present invention will be further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the claimed rights of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0089] It should be understood that in the description of the present invention, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0090] It should be noted that in the description of the present invention, unless otherwise clearly defined and limited, the terms "set", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0091] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves, and general pump equipment for realizing the complete process. However, the above contents do not belong to the main inventive points of the present invention. Those skilled in the art can add and arrange them by themselves based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0092] Example 1

[0093] This example provides a zero-emission and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater, and its flowchart is as Figure 1 shown.

[0094] The zero-emission and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater includes a primary pretreatment module 1, a deep pretreatment module 2, and a concentration and crystallization module 3;

[0095] The primary pretreatment module 1 includes a chemical addition and impurity removal unit 101, a coagulation and sedimentation unit 102, and a flotation unit 103 connected in sequence;

[0096] The deep pretreatment module 2 includes a deep impurity removal unit 201, a deep COD removal unit 202, and a deep hardness removal unit 203 connected in sequence;

[0097] The concentration and crystallization module 3 includes a membrane concentration unit 301, an acid adjustment and degassing unit 302, an evaporation and crystallization unit 303, a liquid-solid separation unit 304, and a mother liquor drying unit 305 connected in sequence; both the membrane concentration unit 301 and the evaporation and crystallization unit 303 are connected to a recycled water storage device.

[0098] Both the coagulation and sedimentation unit 102 and the deep impurity removal unit 201 are connected to a sludge conveying device;

[0099] The liquid-solid separation unit 304 is connected to a sodium sulfate by-product salt storage device;

[0100] The mother liquor drying unit 305 is connected to a miscellaneous salt conveying device.

[0101] The coagulation and sedimentation unit 102 is a high-density sedimentation tank;

[0102] A filter press dehydration device is also provided between the coagulation and sedimentation unit 102 and the sludge conveying device.

[0103] The flotation unit 103 is a dissolved air flotation machine.

[0104] The front view of the deep impurity removal unit is as Figure 2 shown, and the top view is as Figure 3 shown.

[0105] The deep impurity removal unit 201 includes a water inlet pipe 2011, a filter membrane module 2013, and a product water pipe 2015 that are connected in sequence;

[0106] An aeration device is arranged around the filter membrane module 2013;

[0107] The aeration device includes a blower, an air inlet pipe 2016, and an aeration head 2014 that are connected in sequence;

[0108] A sludge discharge pipe 2012 is arranged at the bottom of the deep impurity removal unit 201;

[0109] The sludge discharge pipe 2012 is connected to a pressure filtration and dehydration device;

[0110] The filter membrane module 2013 is a hollow fiber type ultrafiltration membrane, and negative pressure suction is used to discharge water.

[0111] The position of the filter membrane module 2013 is more than 1 / 3 away from the bottom of the pool.

[0112] The deep COD removal unit 202 includes an advanced oxidation device and an activated carbon adsorption device that are connected in sequence;

[0113] The advanced oxidation device is an ozone catalytic oxidation device;

[0114] The deep hardness removal unit 203 is a softening resin bed;

[0115] The membrane concentration unit 301 is a high-pressure reverse osmosis membrane;

[0116] The acid adjustment and degassing unit 302 is a degassing tower;

[0117] The evaporation and crystallization unit 303 includes a vertical tube falling film type evaporator and a forced circulation type crystallizer that are connected in sequence;

[0118] The liquid-solid separation unit 304 includes a thickener and a dehydration device that are connected in sequence;

[0119] The dehydration device is also connected to a drying device;

[0120] The mother liquor drying unit 305 is a drum dryer.

[0121] Example 2

[0122] This example provides a zero-discharge and resource utilization method for petrochemical flue gas desulfurization wastewater. The zero-discharge and resource utilization method for petrochemical flue gas desulfurization wastewater is carried out using the above-mentioned zero-discharge and resource utilization device system for petrochemical flue gas desulfurization wastewater.

[0123] The desulfurized wastewater from petrochemical flue gas in this embodiment is the saline wastewater generated by a petrochemical refinery enterprise after the treatment of the flue gas discharged from the fluid catalytic cracking unit in the dust removal, denitrification, and desulfurization purification sections. The wastewater discharge volume is 20 - 25 m 3 / h, the salt content is 30,000 - 35,000 mg / L, the suspended solid content is 800 - 1000 mg / L, the COD is 300 - 400 mg / L, the hardness is 80 - 100 mg / L, and it also contains a small amount of heavy metal nickel and oil components.

[0124] The zero - discharge and resource - utilization disposal method for the desulfurized wastewater from petrochemical flue gas includes the following steps:

[0125] (1) The wastewater enters the primary pretreatment module. In the chemical addition and impurity removal unit 101, a 20% concentration sodium hydroxide solution and a 30% concentration sodium carbonate solution are sequentially added to the wastewater to make the hardness of the wastewater reach 20 - 30 mg / L; sodium sulfide is added to the wastewater to remove heavy metal nickel; after sufficient stirring and mixing reaction, a heavy - metal and hardness - removal precipitation product is formed; the suspension is pumped into the coagulation and sedimentation unit 102 through a pipeline pump, that is, it enters the high - density sedimentation tank, and polyferric sulfate is added as a coagulant with a dosage of 50 mg / L; polyacrylamide is added as a flocculant with a dosage of 7 mg / L. A large amount of colloidal suspended solids in the wastewater are coagulated and sedimented at the bottom of the high - density sedimentation tank to form sludge, which is then transported to a plate - and - frame filter press for dehydration and then formed into sludge blocks for external disposal; the supernatant of the high - density sedimentation tank is pumped into the air - flotation unit 103 through a pipeline pump, that is, the clear liquid enters the dissolved - air flotation machine. The micro - sized bubbles generated are used to carry a small amount of oil and catalyst fine powder in the wastewater to float to the surface, and the oil - scraping device above the air - flotation machine scrapes off the oil and fine particles on the liquid surface;

[0126] (2) The effluent of the dissolved - air flotation machine enters the advanced pretreatment module 2. It is pumped into the advanced impurity removal unit 201 through the water inlet pipe 2011. Through the interception of the filter membrane module 2013, the suspended solid content in the water produced inside the membrane is less than 1 mg / L, and the produced water is discharged by negative pressure suction through the water production pipe 2015; the generated sludge is transported to a plate - and - frame filter press through the sludge discharge pipe 2012 for dehydration treatment; the residual sodium sulfite in the wastewater is oxidized to sodium sulfate to ensure the purity of the by - product salt; the effluent of the advanced impurity removal unit 201 is sequentially pumped into the advanced COD removal unit 202 and the advanced hardness removal unit 203, that is, the wastewater passes through an ozone - catalytic oxidation device, an activated - carbon adsorption device, and a softening resin bed device in sequence. After treatment, the wastewater only contains inorganic salt components and trace amounts of heavy metals, oil, suspended solids, COD, and hardness, among which the suspended solids are less than 1 mg / L, the COD is less than 20 mg / L, and the hardness is less than 1 mg / L;

[0127] (3) The wastewater after hardness reduction enters the concentration and crystallization module 3. First, it is pumped into the membrane concentration unit 301. Through high-pressure reverse osmosis, the salt content of the wastewater is concentrated to 100,000 - 120,000 mg / L. The membrane-produced water is recycled to the in-plant circulating water field. The membrane concentrate is treated by the acid adjustment and degassing unit 302. That is, the wastewater passes through adding sulfuric acid to adjust the pH to 5.6 and heating up to 93 °C in sequence, and then non-condensable gases such as carbon dioxide and oxygen in the wastewater are removed. After degassing, the wastewater is pumped into the evaporation and crystallization unit 303. That is, after being treated by the MVR falling film evaporation and triple-effect forced circulation crystallization device in sequence, the obtained distillate is collected, heated, and recycled to the in-plant circulating water field. When the solid content of the thick slurry in the crystallizer reaches 20%, it is pumped into the liquid-solid separation unit 304. That is, the thick slurry first enters the thickener to increase the solid content to 40%, and then is pumped into the centrifugal double-pushing type dehydrator. The obtained wet sodium sulfate salt is further dried by a vibrating fluidized bed dryer to obtain dry sodium sulfate salt. A part of the filtrate of the dehydrator is pumped back into the crystallizer for circulation, and the other part is pumped into the mother liquor drying unit 305. That is, through the action of a drum dryer, a small amount of mother liquor is dehydrated and dried to obtain miscellaneous salts for external transportation and disposal, further improving the purity and quality of the by-product sodium sulfate salt.

[0128] In this embodiment, the recovery rate of the wastewater after treatment can reach more than 98%. The recycled water meets the industrial recycled water quality standard and is used in the in-plant circulating water field. The salt recovery rate is high, the miscellaneous salt rate is less than 5%, and the quality of the by-product sodium sulfate salt is high, meeting the requirements of Class I products in the national standard "Industrial Anhydrous Sodium Sulfate" (GB / T 6009 - 2014), and can be sold as an assistant for printing and dyeing, papermaking, and glass making.

[0129] Comparative Example 1

[0130] This comparative example provides a zero-discharge and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater. The difference compared with Example 1 is that a multi-media (quartz sand and anthracite) filtration unit + ultrafiltration unit is used to replace the deep impurity removal unit 201.

[0131] This comparative example also provides a zero-discharge and resource utilization disposal method for petrochemical flue gas desulfurization wastewater. The zero-discharge and resource utilization disposal method for petrochemical flue gas desulfurization wastewater is carried out by using the above-mentioned zero-discharge and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater. Except that the effluent of the dissolved air flotation machine enters the multi-media filtration unit and the ultrafiltration unit in sequence and then enters the deep COD removal unit 202, the rest are the same as in Example 2.

[0132] Comparative Example 2

[0133] This comparative example provides a zero-discharge and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater. The difference compared with Example 1 is that the air flotation unit 103, the deep COD removal unit 202, and the deep impurity removal unit 201 are connected in sequence.

[0134] This comparative example also provides a method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater. The method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater is carried out by using the above-mentioned device system for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater. Except that the effluent of the dissolved air flotation machine is first pumped into the deep COD removal unit 202 and then pumped into the deep impurity removal unit 201, the rest are the same as those in Example 2.

[0135] Comparative Example 3

[0136] This comparative example provides a device system for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater. The difference compared with Example 1 is that the deep impurity removal unit 201, the deep hardness removal unit 203 and the deep COD removal unit 202 are connected in sequence.

[0137] This comparative example also provides a method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater. The method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater is carried out by using the above-mentioned device system for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater. Except that the water produced by the deep impurity removal unit 201 is first pumped into the deep hardness removal unit 203 and then pumped into the deep COD removal unit 202, the rest are the same as those in Example 2.

[0138] The influent water quality indexes of the membrane concentration unit 301 in Example 2 and Comparative Examples 1-3 were measured. Among them, the determination of the suspended solid SS content was carried out according to the "Gravimetric Method for the Determination of Suspended Solids in Water" (GB / T 11901-1989), the determination of the COD content was carried out according to the "Dichromate Method for the Determination of Chemical Oxygen Demand in Water", and the determination of the hardness was carried out according to the "EDTA Titration Method for the Determination of Calcium and Magnesium Ions in Industrial Recirculating Cooling Water" (GB / T 15452-2009). The results are shown in Table 1.

[0139] Table 1

[0140]

[0141] It can be seen from Table 1 as follows:

[0142] (1) It can be seen from the data in Example 2 that the method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater provided by the present invention deeply removes suspended solids, COD and hardness to 0.2 mg / L, 18 mg / L and 0.6 mg / L respectively when the wastewater enters the membrane concentration unit, preventing adverse effects caused by enrichment in the membrane concentration and evaporation crystallization modules, such as high impurity content, membrane fouling, heat exchanger scaling, etc., ultimately resulting in low by-product salt purity, high impurity salt rate, frequent cleaning of membrane components and heat exchangers, and difficulty in achieving long-term stable operation of the device system.

[0143] (2) As can be seen from the data of Example 2 and Comparative Example 1, the difference between Comparative Example 1 and Example 2 is only that the multi-media filtration unit + ultrafiltration unit is used to replace the deep impurity removal unit. The COD content of the influent water of the membrane concentration unit obtained in Example 2 is significantly lower than that in Comparative Example 1. Thus, it can be seen that through the deep impurity removal unit of the present invention, not only can the suspended solid content be reduced, but also a large number of micro-sized bubbles can be generated by setting aeration heads, which contact and oxidize with the wastewater, oxidize the residual sulfite in the wastewater into sulfate, reduce the COD of non-organic impurities, and at the same time improve the purity of the by-product sodium sulfate. In addition, by setting aeration heads to generate a large number of micro-sized bubbles to continuously scrub and clean the surface of the filter membrane online, the high flux and high rejection rate of the filter membrane module are maintained, and the cleaning cycle of the membrane module is extended.

[0144] (3) As can be seen from the data of Example 2 and Comparative Example 2, the difference between Comparative Example 2 and Example 2 is only that the order of the deep impurity removal unit and the deep COD removal unit is swapped. The hardness of the influent water of the membrane concentration unit obtained in Example 2 is significantly lower than that in Comparative Example 2. Thus, it can be seen that it is beneficial to the removal effect of wastewater hardness to enter the deep impurity removal unit first and then enter the deep COD removal unit. This is because the residual reducing sulfite in the wastewater is not first treated by the deep impurity removal unit and converted into sulfate, but directly enters the deep COD removal unit, which will reduce the COD degradation efficiency of devices such as the ozone catalytic oxidation device. When the COD content in the wastewater increases, it will reduce the softening treatment effect of the deep hardness removal unit such as the softening resin bed device, resulting in an increase in the hardness value of the effluent from the softening resin bed.

[0145] (4) As can be seen from the data of Example 2 and Comparative Example 3, the difference between Comparative Example 3 and Example 2 is only that the order of the deep COD removal unit and the deep hardness removal unit is swapped. The hardness of the influent water of the membrane concentration unit obtained in Example 2 is significantly lower than that in Comparative Example 3. Thus, it can be seen that it is beneficial to the removal effect of wastewater hardness to enter the deep COD removal unit first and then enter the deep hardness removal unit. This is because the organic impurity COD in the wastewater is not first removed by the deep COD removal unit, and the COD in the wastewater will reduce the softening treatment effect of the deep hardness removal unit such as the softening resin bed device, resulting in an increase in the final effluent hardness value.

[0146] In summary, the zero-discharge and resource utilization device system for petrochemical flue gas desulfurization wastewater provided by the present invention has a compact structure, stable and reliable operation, low energy consumption and material consumption during operation, realizes high-efficiency reuse of water in the wastewater, and high-value utilization of salts.

[0147] The applicant declares that the detailed structural features of the present invention are illustrated by the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A zero-emission and resource-based treatment device system for petrochemical flue gas desulfurization wastewater, characterized in that, The petrochemical flue gas desulfurization wastewater zero-discharge and resource utilization disposal device system includes a primary pretreatment module (1), a deep pretreatment module (2), and a concentration and crystallization module (3); The primary pretreatment module (1) includes a chemical addition and impurity removal unit (101), a coagulation and sedimentation unit (102), and a flotation unit (103) connected in sequence; The deep pretreatment module (2) includes a deep impurity removal unit (201), a deep COD removal unit (202), and a deep hardness removal unit (203) connected in sequence; The concentration and crystallization module (3) includes a membrane concentration unit (301), an acid adjustment and degassing unit (302), an evaporation and crystallization unit (303), a liquid-solid separation unit (304), and a mother liquor drying unit (305) connected in sequence; the membrane concentration unit (301) and the evaporation and crystallization unit (303) are both connected to a recycled water storage device.

2. The zero-emission and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater according to claim 1, characterized in that, Both the coagulation and sedimentation unit (102) and the deep impurity removal unit (201) are connected to a sludge conveying device; Preferably, the liquid-solid separation unit (304) is connected to a sodium sulfate by-product salt storage device; Preferably, the mother liquor drying unit (305) is connected to a miscellaneous salt conveying device.

3. The zero-emission and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater according to claim 1 or 2, characterized in that, The coagulation and sedimentation unit (102) includes any one or a combination of a high-density sedimentation tank, a vertical flow sedimentation tank, or an inclined plate sedimentation tank; Preferably, a filter press dehydration device is further provided between the coagulation and sedimentation unit (102) and the sludge conveying device.

4. The zero-emission and resource utilization disposal device system for petrochemical flue gas desulfurization wastewater according to any one of claims 1 to 3, characterized in that, The flotation unit (103) includes a dissolved air flotation machine.

5. The zero - discharge and resource - utilization disposal device system for petrochemical flue gas desulfurization wastewater according to any one of claims 1 to 4, characterized in that, The deep impurity removal unit (201) includes a water inlet pipe (2011), a filter membrane module (2013), and a water production pipe (2015) connected in sequence; Preferably, an aeration device is provided around the filter membrane module (2013); Preferably, the aeration device includes a blower, an air inlet pipe (2016), and an aeration head (2014) connected in sequence; Preferably, a sludge discharge pipe (2012) is provided at the bottom of the deep impurity removal unit (201); Preferably, the sludge discharge pipe (2012) is connected to a filter press dehydration device; Preferably, the filter membrane module (2013) includes a hollow fiber type ultrafiltration membrane and uses negative pressure suction for water outlet; Preferably, the position of the filter membrane module (2013) is more than 1 / 3 above the bottom of the pool.

6. The zero - discharge and resource - utilization disposal device system for petrochemical flue gas desulfurization wastewater according to any one of claims 1 to 5, characterized in that, The deep COD removal unit (202) includes a advanced oxidation device and an activated carbon adsorption device connected in sequence; Preferably, the advanced oxidation device includes any one of an ozone catalytic oxidation device, an electro-catalytic oxidation device, or a photo-catalytic oxidation device; Preferably, the deep hardness removal unit (203) includes a softening resin bed; Preferably, the membrane concentration unit (301) includes a high-pressure reverse osmosis membrane; Preferably, the acid adjustment and degassing unit (302) includes a degassing tower; Preferably, the evaporation and crystallization unit (303) includes a vertical tube falling film type evaporator and a forced circulation type crystallizer connected in sequence; Preferably, the liquid-solid separation unit (304) includes a thickener and a dehydration device connected in sequence; Preferably, the dehydration device is further connected to a drying device; Preferably, the mother liquor drying unit (305) includes a drum dryer.

7. A method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater, characterized in that, The zero-emission and resource utilization treatment method for petrochemical flue gas desulfurization wastewater is carried out by using the zero-emission and resource utilization treatment device system for petrochemical flue gas desulfurization wastewater described in any one of claims 1 to 6; The zero-emission and resource utilization treatment method for petrochemical flue gas desulfurization wastewater includes the following steps: (1) The petrochemical flue gas desulfurization wastewater enters the primary pretreatment module (1). After removing hardness and heavy metals through the chemical addition and impurity removal unit (101), it enters the coagulation sedimentation unit (102) and the air flotation unit (103) to remove suspended solids and oil; (2) The treated wastewater enters the advanced pretreatment module (2), and successively passes through the advanced impurity removal unit (201) to further remove suspended solids and some COD impurities and convert the residual sodium sulfite salt in the wastewater into sodium sulfate salt, enters the advanced COD removal unit (202) to remove refractory organic matter, and enters the advanced hardness removal unit (203) to reduce the hardness of the wastewater; (3) The wastewater with reduced hardness enters the concentration and crystallization module (3). The inorganic salts in the wastewater are concentrated successively through the membrane concentration unit (301), the CO2 and non-condensable gases in the wastewater are discharged through the acid adjustment and degassing unit (302), the inorganic salt ions in the wastewater are evaporated and concentrated to precipitate crystal salt particles to form a thick slurry through the evaporation and crystallization unit (303), and the sodium sulfate by-product salt is obtained through sedimentation enrichment and drying treatment in the liquid-solid separation unit (304) to realize the resource utilization of the wastewater; the filtrate generated by the liquid-solid separation unit (304) enters the mother liquor drying unit (305) for dehydration and drying to obtain miscellaneous salts; the water produced by the membrane concentration unit (301) is recycled, and the distilled liquid generated by the evaporation and crystallization unit (303) is recycled to realize the zero-emission of the wastewater.

8. The zero - discharge and resource - utilization treatment method for petrochemical flue gas desulfurization wastewater according to claim 7, characterized in that, The sludge generated by the coagulation sedimentation unit (102) and the advanced impurity removal unit (201) enters the sludge conveying device; Preferably, the sodium sulfate by-product salt obtained by the liquid-solid separation unit (304) enters the sodium sulfate by-product salt storage device; Preferably, the miscellaneous salts obtained by the mother liquor drying unit (305) enter the miscellaneous salt conveying device.

9. The zero-emission and resource utilization method for desulfurized waste water from petrochemical flue gas according to claim 7 or 8, characterized in that, A first precipitant is added in the chemical addition and impurity removal unit (101); Preferably, the first precipitant includes sulfide or alkali solution; Preferably, the dosage of the first precipitant is 1.05 to 1.1 times the theoretical dosage required for removing heavy metals; Preferably, a second precipitant is also added in the chemical addition and impurity removal unit (101); Preferably, the second precipitant includes sodium hydroxide or sodium carbonate; Preferably, the dosage of the second precipitant is 1.05 to 1.1 times the theoretical dosage required for removing hardness.

10. The method for zero discharge and resource utilization of petrochemical flue gas desulfurization wastewater according to any one of claims 7 to 9, characterized in that, A coagulant and a flocculant are added in the coagulation sedimentation unit (102); Preferably, the coagulant includes polyferric sulfate, and the dosage is 10 to 100 mg / L; Preferably, the flocculant includes polyacrylamide, and the dosage is 1 to 10 mg / L; Preferably, the pH is adjusted to 5 to 6 by adding acid before the wastewater enters the degassing tower of the acid adjustment and degassing unit (302), and the temperature is heated to 90 to 95 °C.

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