Sulfate-containing waste liquid treatment system and method for acrylonitrile and acrylonitrile combination device

Abstract

The invention provides a sulfate-containing waste liquid treatment system and a sulfate-containing waste liquid treatment method for acrylonitrile and a combination device thereof, the system comprises at least two sets of waste liquid treatment units and a set of flue gas treatment unit, sulfate waste liquid is divided into two strands to enter the two sets of waste liquid treatment units for combustion, waste heat utilization and quenching purification, the discharged sulfur-containing flue gas is collected and enters a set of flue gas treatment unit, the sulfur-containing flue gas subjected to deep cooling, demisting and drying can be directly used for producing high-purity sulfuric acid, and a two-end and one-tail mode is adopted, so that the operation flexibility of the system is improved, and the treatment pressure is reduced. In the waste liquid treatment unit, a high-temperature reaction device adopts segmented air distribution, so that sufficient combustion of waste liquid is ensured, and SO2 loss is reduced; a special temperature field and structural design in the waste heat boiler can prevent the heat exchange device from scaling and blocking; a venturi scrubber is adopted in the quenching purification device to quench the flue gas, and a protective liquid film is formed on the contact interface of the high-temperature flue gas and a liquid phase, so that the temperature of equipment is effectively reduced, and corrosion of the high-temperature flue gas is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of sulfate-containing waste liquid recovery and treatment, and further to a sulfate-containing waste liquid treatment system and method for acrylonitrile and a combined device thereof. Background Art

[0002] Sulfuric acid is an important inorganic strong acid that can react with most metals. It has strong acidity, oxidizing properties and wide solubility. It can be used as an acid-base neutralizing agent, catalyst, solvent, electrolyte, dehydrating agent, sulfonating agent, etc. It is widely used in the petrochemical industry and is an important chemical raw material. For example, in the acrylonitrile joint unit, sulfuric acid is used as an acid-base neutralizing agent to remove the remaining ammonia after the reaction; in the unit for producing MMA by the acetone cyanohydrin method, sulfuric acid is used as a raw material for the amidation reaction to produce MMA products; in the alkylation unit, sulfuric acid is used as a catalyst to produce high-octane gasoline, etc. However, during the production process of these units, sulfuric acid is eventually discharged in the form of waste liquid containing sulfuric acid (salt). In order to treat these waste liquids containing sulfuric acid (salt), the industry widely uses the waste acid regeneration process, which performs a secondary conversion on the waste liquid containing sulfuric acid (salt), converting the originally discarded industrial waste liquid into a sulfuric acid raw material that can be put into production again, realizing the recycling and resource recovery of sulfuric acid, greatly improving the efficiency of raw material use, reducing environmental pollution, and having huge environmental, social and economic benefits. It is a green development process.

[0003] The existing waste acid regeneration device uses sulfuric acid (salt) waste liquid as raw material and produces high-concentration sulfuric acid products through high-temperature cracking, waste heat recovery, rapid cooling purification, conversion absorption and other process unit operations. Since the waste liquid contains a large amount of sulfur-containing compounds, nitrogen-containing compounds, catalyst particles and metal salts, there are many problems in the operation of the device, mainly including: (1) NO at the cracking furnace outlet xExcessive and large amounts of SO2 are converted into SO3, resulting in large sulfur losses and reduced device yields; (2) There is a certain amount of catalyst particles in the sulfuric acid (salt) waste liquid, which forms metal dust after incineration in the cracking furnace and enters the waste heat recovery system. The waste heat boiler adopts a fire tube boiler, and the hot flue gas flows through the tube. The metal dust in the flue gas is molten after heat exchange and cooling with the boiler water, and adheres to the inner wall of the heat exchange tube, causing scaling or blockage of the furnace tube, reducing the heat transfer efficiency. After running for a period of time, manual cleaning must be performed, which seriously affects the continuous operation cycle of the waste heat boiler system; (3) The flue gas after incineration contains a large amount of SO2 and SO3, which forms a high temperature environment and an acid environment in the subsequent rapid cooling and purification equipment, causing serious equipment corrosion. These directly or indirectly reduce the operating efficiency of the waste acid regeneration device and cause the device to stop frequently, increasing the operating cost of the device; as an environmental protection device, the waste acid regeneration device frequently stops and directly affects the continuous operation cycle of the upstream production device, bringing huge economic losses to the enterprise. At the same time, due to the limited scale of the waste acid regeneration device, it is unable to meet the needs of centralized treatment of sulfuric acid (salt) waste liquid in the whole plant. The existing industrial production often adopts the mode of supporting the construction of the upstream main device and the waste acid regeneration device, resulting in a huge waste of construction and production costs. With the large-scale development of chemical plants, the treatment volume of sulfuric acid (salt) waste liquid has increased sharply, and the problem of limited plant scale has become increasingly prominent. How to expand the treatment capacity of a single waste acid regeneration device is also an urgent problem that needs to be solved.

[0004] Patent CN103552992A discloses a system and method for dry acid production from sulfur-containing waste liquid, which includes a sulfur-containing waste liquid incineration device, a furnace gas treatment device, a conversion device and an absorption device. The incineration device includes an incinerator, and the furnace gas treatment device includes a waste heat boiler, an adiabatic evaporation fully enclosed pickling device, a cooling device, an electric demister and a drying tower that are connected in sequence. The conversion device includes a 3+2 five-stage conversion device or a 3+1 four-stage double conversion device, and the absorption device includes a first absorption tower and a second absorption tower. This process can recycle and recycle sulfuric acid (salt) waste liquid, which has huge environmental and economic benefits. The process method described in this patent is basically consistent with the existing waste acid regeneration process, and can produce high-concentration sulfuric acid products, but it does not solve the problems of waste heat boiler blockage, quenching equipment corrosion, and limited device scale during the operation of the device.

[0005] Patent CN106379868A discloses a method for producing sulfuric acid by incinerating sulfur-containing waste liquid. The sulfur-containing waste liquid is sent to an incinerator for incineration. Under high temperature, ammonia salts, elemental sulfur, organic matter, etc. in the sulfuric acid (salt) waste liquid undergo decomposition and oxidation reactions. The furnace gas containing sulfur dioxide is used to produce commercial-grade sulfuric acid. This invention uses the high-temperature gas generated after the waste liquid is incinerated, and uses a waste heat boiler to recover waste heat to generate steam, with a high thermal energy utilization rate; the gas cooled by the waste heat boiler then enters a two-stage air preheater, and the furnace gas is cooled and then enters a power wave scrubber in the purification section to reduce fuel consumption, while effectively increasing the SO2 concentration of the burned gas, which is more conducive to the production of sulfuric acid. The contact method is used to prepare sulfuric acid, with a high SO2 conversion rate, a short process flow, and simple operation. This patent recovers the flue gas from the incinerator outlet through waste heat recovery and reduces the temperature to 450°C through a two-stage air preheater before entering a dynamic wave scrubber. However, during operation, the waste heat boiler and air preheater are prone to ash accumulation, clogging, and corrosion of the heat exchange tubes, making it impossible to ensure long-term operation of the device. At the same time, the flue gas is cooled to 450°C before entering the dynamic wave scrubber, causing a large amount of heat loss. The rapid cooling purification device uses a dynamic wave scrubber, which has the problems of large footprint and high energy consumption. Summary of the invention

[0006] In view of the problems that the existing sulfate-containing waste liquid treatment system is prone to dust accumulation and blockage, equipment corrosion, and large SO2 loss, the purpose of the present invention is to provide a sulfate-containing waste liquid treatment system and method for acrylonitrile and its combined unit. The system adopts a "two-head and one-tail" mode, namely two sets of independent waste liquid treatment units and one set of flue gas treatment unit. The two sets of waste liquid treatment units can be flexibly switched and complemented with each other, which improves the operational flexibility of the equipment and disperses the treatment pressure. The flue gas treatment unit effectively integrates the sulfur-containing flue gas generated during the treatment process. Through deep cooling, demisting and drying treatment, the sulfur-containing gas can be directly used to produce high-purity sulfuric acid. Remarkable results have been achieved in the resource utilization of waste liquid. It also has the advantages of long operation cycle and high treatment efficiency, and has broad application prospects.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A sulfate-containing waste liquid treatment system for acrylonitrile and its combined device comprises: an oxygen-enriched control distributor, a waste liquid treatment unit and a flue gas treatment unit, wherein at least two waste liquid treatment units are provided, and multiple waste liquid treatment units are provided in parallel, and flue gas discharged from multiple waste liquid treatment units is collected and enters the flue gas treatment unit; the waste liquid treatment unit comprises a high-temperature reaction device, a waste heat recovery device and a rapid cooling purification device connected in sequence; the oxygen-enriched control distributor is used to transport air and oxygen-enriched mixed gas to each of the high-temperature reaction devices respectively; the high-temperature reaction device is used to burn sulfate-containing waste liquid with oxygen-enriched gas; the waste heat recovery device is used to recover waste heat from the flue gas discharged from the high-temperature reaction device; the rapid cooling purification device is used to cool and wash the flue gas; the flue gas treatment unit comprises a secondary cooling device, a demisting device and an absorption drying device connected in sequence to the outlet of the rapid cooling purification device, and is used to perform secondary cooling, dehydration, demisting and dehydration on the purified flue gas discharged from the rapid cooling purification device.

[0009] In some embodiments, the high-temperature reaction device includes a cracking furnace, a burner, and a plurality of air distribution pipelines for supplying oxygen-rich gas, the cracking furnace is used to supply sulfate-containing waste liquid with oxygen-rich gas for high-temperature thermal oxidation reaction, the interior of the cracking furnace includes a reduction section and an oxidation section, the reduction section is connected to the outlet of the burner; the burner is used to mix the oxygen-rich gas and fuel and ignite to produce a flame; the setting of the plurality of air distribution pipelines includes scheme one or scheme two: scheme one: the plurality of air distribution pipelines include at least one secondary air distribution pipeline connected to the burner or the reduction section and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the reduction section and the oxidation section respectively; scheme two: the plurality of air distribution pipelines include at least one primary air distribution pipeline connected to the burner, at least one secondary air distribution pipeline connected to the reduction section, and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the burner, the reduction section and the oxidation section respectively.

[0010] In some embodiments, the waste heat recovery device includes: a waste heat boiler body, a steam drum, a boiler water booster pump and a plurality of cleaning devices; the steam drum has a boiler water inlet, a saturated water outlet, a saturated steam outlet and a gas-liquid mixture inlet; a radiation section, a superheating section and an evaporation section are sequentially arranged in the waste heat boiler body from the inlet to the outlet, the waste heat boiler body where the radiation section is located is a cavity with a water-cooled wall tube panel on the inner wall, and the inlet and outlet of the water-cooled wall tube panel are respectively connected to the saturated water outlet and the gas-liquid mixture inlet; the superheating section and the evaporation section are both provided with a bare tube heat exchanger, the inlet of the bare tube heat exchanger of the superheating section is connected to the saturated steam outlet, and the outlet is used to output superheated steam heated by high-temperature flue gas; the inlet and outlet of the bare tube heat exchanger of the evaporation section are respectively connected to the saturated water outlet and the gas-liquid mixture inlet; the cleaning device is provided at the waste heat boiler bodies corresponding to the radiation section, the superheating section and the evaporation section, for removing impurities inside the waste heat boiler body.

[0011] In some embodiments, the secondary cooling device includes: a cooling tower and a cooler, wherein the cooling tower is provided with a spraying device and a packing layer; the bottom of the cooling tower, the cooler and the spraying device are connected through a pipeline to cool the bottom liquid of the cooling tower and then spray it again.

[0012] In some embodiments, the demister device includes a water sealer and a plurality of demisters, and the plurality of demisters are connected in series or in parallel; the water sealer is connected to a pipeline between the demister and the drying device.

[0013] In some embodiments, the absorption drying device includes a drying tower, a cooling sulfuric acid circulation pipeline, and an acid storage tank and an acid cooler arranged on the cooling sulfuric acid circulation pipeline; the inlet of the drying tower is connected to the outlet of the demisting device; the bottom of the drying tower is connected to the circulating liquid inlet at the top of the drying tower through the cooling sulfuric acid circulation pipeline, the acid storage tank is used to mix and store the bottom liquid of the drying tower with high-concentration sulfuric acid, and the acid cooler is used to cool the circulating liquid in the cooling sulfuric acid circulation pipeline.

[0014] In some embodiments, the quench purification device includes: a venturi scrubber, a washing spray pipeline, and a quench device; the venturi scrubber includes a flue gas inlet, a reduced diameter section, a throat diameter, an expanded diameter section, and a sedimentation section from top to bottom, and the flue gas inlet is connected to the outlet of the waste heat recovery device; the quench device includes a quench tower, a cooling circulation pipeline, a buffer tank and a circulating liquid cooler, the quench tower is connected to the venturi scrubber through a flue gas pipeline, the tower bottom of the quench tower is connected to the bottom of the venturi scrubber through the washing spray pipeline, and is connected to the flue gas inlet and the expanded diameter section together; the cooling circulation pipeline is used to cool the spray liquid in the quench tower and re-input it into the quench tower for circulating spray; the buffer tank is connected to the quench tower for collecting the spray liquid in the tower, and the circulating liquid cooler is used to cool the spray liquid; the overflow port of the buffer tank is connected to the tower bottom of the quench tower, and the overflow port is located in the middle of the buffer tank in the vertical direction.

[0015] The present invention also provides a method for treating sulfate-containing waste liquid for acrylonitrile and its combined device, using the above-mentioned sulfate-containing waste liquid treatment system, the high-temperature reaction device includes a cracking furnace and a burner, and the cracking furnace is provided with a reduction section and an oxidation section; the steps of the method are as follows: S1, the sulfate-containing waste liquid from the upstream is atomized and transported to the cracking furnace, the oxygen-rich gas and the fuel are mixed through the burner and flame is generated and then input into the reduction section, the sulfate-containing waste liquid reacts with the oxygen-rich gas and the fuel in the reduction section and the oxidation section in turn; the flue gas discharged from the cracking furnace enters the waste heat recovery device and the quenching purification device in turn for waste heat recovery, quenching and washing; S2, the flue gas discharged from each of the quenching purification devices is collected and enters the secondary cooling device for deep cooling, then enters the demisting device and the absorption drying device for demisting and drying, and then is sent to the downstream conversion absorption device.

[0016] In some embodiments, the high temperature reaction device further comprises: a plurality of air distribution pipelines, and the arrangement of the plurality of air distribution pipelines comprises scheme 1 or scheme 2:

[0017] The scheme 1: the plurality of air distribution pipelines include at least one secondary air distribution pipeline connected to the burner or the reduction section and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-enriched gas to the burner or the reduction section and the oxidation section respectively; in the step S1, secondary air distribution and tertiary air distribution are respectively performed to the reduction section and the oxidation section according to a set oxygen-enriched flow ratio, and the set oxygen-enriched flow ratio is: primary air distribution: secondary air distribution = (6-9): (1-4);

[0018] The second scheme: the multiple air distribution pipelines include at least one primary air distribution pipeline connected to the burner, at least one secondary air distribution pipeline connected to the reduction section, and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the burner, the reduction section and the oxidation section respectively; in the step S1, primary air distribution, secondary air distribution and tertiary air distribution are respectively performed to the burner, the reduction section and the oxidation section according to a set oxygen-rich flow ratio; the set oxygen-rich flow ratio is: primary air distribution: secondary air distribution: tertiary air distribution = (5~8): (1~3): (1~2).

[0019] In some embodiments, the temperature of the reduction section is 900-1400°C, and the residence time of the flue gas is 2-4s; the temperature of the oxidation section is 800-1200°C, and the residence time of the flue gas is 2-6s; the oxygen content in the flue gas at the outlet of the oxidation section is 1%-6% mol; and\or, the method for treating sulfate-containing waste liquid also includes: before entering the absorption and drying device, inputting oxygen into the purified flue gas discharged from the demisting device to adjust the molar ratio of O2 and SO2 in the purified flue gas to 0.8-2.

[0020] Compared with the prior art, the system and method for resource-based treatment of sulfate-containing wastewater provided by the present invention have the following beneficial effects:

[0021] 1. The sulfate-containing waste liquid treatment system provided by the present invention adopts a "two-head and one-tail" mode, namely, two sets of independent waste liquid treatment units and one set of flue gas treatment unit. The two sets of independent waste liquid treatment units can realize flexible switching and complementarity of waste liquid treatment, and enhance the operational flexibility of the device. At the same time, this design also makes the system more convenient during maintenance and overhaul, and the overall operation will not be affected by the shutdown of a single unit. The two sets of independent waste liquid treatment systems can also disperse the processing load, and the operating pressure of each unit is reduced, which can extend the service life of the equipment and the operating cycle of the system. A set of special flue gas treatment units is used as the "tail end" processing link, which effectively integrates the sulfur-containing flue gas generated in the waste liquid treatment process. The sulfur-containing gas after deep cooling, demisting and drying can directly produce high-purity sulfuric acid. The "two-head and one-tail" type sulfate-containing waste liquid system has efficient and stable processing performance, and has also achieved remarkable results in optimizing the utilization of waste liquid resources, and has broad application prospects.

[0022] 2. In the waste liquid treatment unit provided by the present invention, an oxygen-enriched control distributor is used to make the distribution of air and oxygen more uniform. The concentration unevenness of the oxygen-enriched air before entering the cracking furnace is less than 0.5%. The uniform oxygen-enriched air makes the temperature field in the cracking furnace more uniform, reduces the amount of semi-coke produced by uneven combustion, thereby alleviating the difficulty of the downstream waste heat boiler in treating high-temperature ash, and reduces the probability of furnace tube adhesion, thereby improving the operating efficiency and reliability of the overall system;

[0023] 3. In the high temperature reaction device provided by the present invention, a segmented air distribution design is adopted to strictly control the temperature, air excess coefficient and residence time of each section in the cracking furnace, thereby ensuring the combustion effect and effectively reducing the loss of SO2 and NO x The production of.

[0024] 4. Different from the traditional fire tube boiler, the waste heat boiler provided by the present invention adopts a unique temperature field and structural design in the radiation section, superheating section and evaporation section, which solves the problems of heat exchange tubes in the existing device being extremely easy to corrode, clog, and difficult to clean. Combined with the boiler water forced circulation process, the risk of equipment corrosion is reduced from the equipment welding process. This comprehensive improvement greatly prolongs the equipment operation cycle and improves the economic benefits of the device;

[0025] 6. In the quench purification device provided by the present invention, the design of the Venturi scrubber with a specific structure solves the problem of large floor space and high energy consumption of the traditional dynamic wave scrubbing equipment. At the same time, the special structural design of the Venturi scrubber enables a protective liquid film to be formed at the interface between the high-temperature flue gas and the liquid phase, thereby reducing the surface temperature of the equipment, preventing high-temperature flue gas corrosion, extending the equipment operation cycle, and improving the durability of the equipment;

[0026] 7. The method for treating sulfuric acid (salt)-containing waste liquid provided by the present invention comprises the following steps: the waste liquid containing sulfuric acid (salt) is introduced into two sets of independently operated waste liquid treatment units, and undergoes combustion, waste heat utilization and rapid cooling and washing treatment in sequence; the sulfur-containing flue gas discharged from the two sets of waste liquid treatment units is collected and then enters a set of flue gas treatment units for secondary cooling, demisting and drying treatment; the high-sulfur and dry gas phase finally obtained can be used to produce high-purity sulfuric acid, effectively converting the sulfuric acid component in the waste liquid, realizing the recycling of sulfuric acid, and achieving resource regeneration and value enhancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of a waste liquid treatment unit provided by the present invention;

[0028] Figure 2 A schematic diagram of the structure of a flue gas treatment unit provided by the present invention;

[0029] Figure 3 A schematic diagram of the structure of a high temperature reaction device provided by the present invention;

[0030] Figure 4 A schematic diagram of the structure of the waste heat recovery device provided by the present invention;

[0031] Figure 5 A schematic diagram of the structure of the rapid cooling and purification device provided by the present invention;

[0032] Figure 6A schematic structural diagram of a specific implementation of the flue gas treatment unit provided by the present invention.

[0033] Description of Figure Numbers:

[0034] 1—high temperature reaction device; 11—cracking furnace; 110—reduction section; 111—oxidation section; 12—burner; 13—secondary air distribution pipeline; 14—secondary air distribution pipeline; 15—tertiary air distribution pipeline; 16—atomizing medium pipeline; 17—air preheating device; 18—oxygen enrichment control distributor;

[0035] 2—waste heat recovery device; 21—waste heat boiler body; 210—radiation section; 211—superheating section; 212—evaporation section; 22—steam drum; 220—boiler water inlet; 221—saturated water outlet; 222—saturated steam outlet; 223—gas-liquid mixture inlet; 23—boiler water booster pump; 24—ash cleaning device;

[0036] 3—quenching purification device; 31—Venturi scrubber; 310—smoke inlet; 311—reduced diameter section; 312—throat diameter; 313—expanded diameter section; 314—sedimentation section; 315—conical bottom; 316—smoke duct; 32—quenching tower; 320—liquid collector; 321—liquid collecting pipe; 322—packing layer; 323—spraying layer; 324—demister; 33—cooling circulation pipeline; 34—buffer tank; 340—overflow port; 35—quenching tower circulation pump; 36—circulating liquid cooler; 37—washing spray pipeline; 38—washing booster pump;

[0037] 4—secondary cooling device; 41—cooling tower; 42—cooler; 43—cooling tower circulation pump;

[0038] 5—demist device; 51—demist device; 52—water sealer;

[0039] 6—absorption drying device; 61—drying tower; 62—cooling sulfuric acid circulation pipeline; 63—acid cooler; 64—acid storage tank;

[0040] 7—Booster fan. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0042] In order to simplify the drawings, only the parts related to the invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0043] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0044] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0046] Example 1

[0047] The present invention provides a system for recycling sulfate-containing wastewater. Figure 1 and Figure 2 As shown, the system includes a waste liquid treatment unit and a flue gas treatment unit, wherein at least two waste liquid treatment units are provided, and the multiple waste liquid treatment units are provided in parallel, and the flue gas discharged from the multiple waste liquid treatment units is collected and enters the flue gas treatment unit for treatment. Specifically:

[0048] The waste liquid treatment unit comprises a high temperature reaction device 1, a waste heat recovery device 2 and a quenching purification device 3 connected in sequence, wherein the high temperature reaction device 1 is used to make the sulfate-containing waste liquid and the oxygen-rich gas undergo a high temperature thermal oxidation reaction, the waste heat recovery device 2 is used to recover the waste heat of the flue gas discharged from the high temperature reaction device 1, and the quenching purification device 3 is used to cool and wash the flue gas. Figures 1 to 6 Specifically describe the structure of the above unit:

[0049] (I) High temperature reaction device 1

[0050] like Figure 1 and Figure 3 As shown, the high temperature reaction device 1 includes a cracking furnace 11, a burner 12, and a plurality of air distribution pipelines for supplying oxygen-rich gas.

[0051] The interior of the cracking furnace 11 is a cavity, which can be used for burning sulfate-containing waste liquid and oxygen-rich gas, and this process also requires the introduction of fuel for combustion-supporting. The interior of the cracking furnace 11 is divided into a reduction section 110 and an oxidation section 111. The form of the cracking furnace 11 can be selected as a vertical furnace, a horizontal furnace or an L-shaped cracking furnace 11, and the cracking furnace 11 is a negative pressure furnace, which can effectively prevent the leakage of toxic gases. The burner 12 is located at the furnace top of the cracking furnace 11. Taking the L-shaped cracking furnace 11 shown in the figure as an example, the vertical section is the reduction section 110, and the horizontal section is the oxidation section 111. The burner 12 is located at the top of the reduction section 110.

[0052] like Figure 3 As shown, the reduction section 110 is connected to the waste liquid pipeline. The sulfate-containing waste liquid involved in the present invention includes but is not limited to ammonium sulfate waste liquid, MMA acid water, sulfuric acid solution, alkylation waste acid and other acidic waste liquids, which are respectively connected to the top and the middle of the reduction section 110 through their respective waste liquid pipelines and enter the cracking furnace 11 for reaction.

[0053] Preferably, in order to improve the combustion effect of the sulfate-containing waste liquid, an atomizing device for atomizing the sulfate-containing waste liquid is added, including multiple atomizing medium pipelines 16, and each waste liquid pipeline is correspondingly provided with an atomizing medium pipeline 16. The atomizing medium can be selected from steam, air, nitrogen, etc., and the sulfate-containing waste liquid is atomized and then input into the reduction section 110. The atomized waste liquid has a larger surface area, which makes it more fully contact with oxygen, thereby promoting more complete and more efficient combustion.

[0054] The reduction section 110 is also connected to the outlet of the burner 12. The fuel and a portion of the oxygen-rich gas are mixed in the burner 12 and ignited to generate a flame, thereby providing heat for the high-temperature thermal oxidation reaction of the sulfate-containing waste liquid in the reduction section.

[0055] Preferably, when the cracking furnace 11 is a vertical furnace or an L-shaped cracking furnace 11, the burner 12 is arranged at the top of the vertical reduction section 110, and when the cracking furnace 11 is a horizontal furnace, the burner 12 is arranged at the furnace head position.

[0056] Furthermore, the burner is also provided with a fuel pipeline and a spray gun. The above-mentioned fuel includes but is not limited to fuel gas, fuel oil, high calorific value tail gas, high calorific value waste liquid, etc. The fuel pipeline should be coordinated with the above-mentioned atomizing steam pipeline.

[0057] There are two solutions for setting up the above-mentioned multiple air distribution pipes:

[0058] Option 1:

[0059] The multiple air distribution pipelines include at least one secondary air distribution pipeline 14 connected to the burner 12 or the reduction section and at least one tertiary air distribution pipeline 15 connected to the oxidation section, so as to supply oxygen-rich gas to the burner 12 or the reduction section 110 and to the oxidation section 111 respectively.

[0060] Option 2:

[0061] The plurality of air distribution pipelines include at least one primary air distribution pipeline 13 connected to the burner 12, at least one secondary air distribution pipeline 14 connected to the reduction section, and at least one tertiary air distribution pipeline 15 connected to the oxidation section, so as to supply oxygen-rich gas to the burner 12, the reduction section 110 and the oxidation section 111 respectively. The primary air distribution pipeline 13 passes a portion of the oxygen-rich gas into the burner 12, and after mixing and reacting with the fuel to generate flames and release a large amount of heat, the temperature of the reduction section 110 in the cracking furnace 11 is increased to above 900-1400° C., providing heat for the high-temperature thermal oxidation reaction between the waste liquid in the reduction section 110 and the oxygen-rich gas input again by the secondary air distribution pipeline 14. The tertiary air distribution pipeline 15 inputs a portion of the oxygen-rich gas into the oxidation section 111, which can not only ensure that the organic matter in the cracking furnace 11 can be completely burned, but also control the oxygen content in the flue gas at the outlet of the cracking furnace 11.

[0062] Regardless of the first or second solution, according to the specific situation, it can be considered to configure multiple primary air distribution pipelines 13, secondary air distribution pipelines 14 and tertiary air distribution pipelines 15.

[0063] It should be noted that the above-mentioned “once”, “twice” and “thrice” are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0064] Furthermore, the high temperature reaction device 1 is also provided with an air preheating device 17 and an oxygen enrichment control distributor 18. The function of the air preheating device 17 is to heat the room temperature air to 300-700°C to reduce the fuel consumption of the cracking furnace 11. The heating method includes but is not limited to an incinerator, electric heating, and steam heating.

[0065] The oxygen enrichment control distributor 18 is connected to the air preheating device 17 to mix the preheated air with pure oxygen to obtain oxygen-enriched air with uniform concentration. The oxygen content of the oxygen-enriched air is 22% to 75%. The temperature of the mixed oxygen-enriched air is 300 to 700°C, preferably 450 to 650°C.

[0066] like Figure 3As shown, when two waste liquid treatment units are set up, an air preheating device 17 and an oxygen enrichment control distributor 18 can be shared. The outlet of the oxygen enrichment control distributor 18 is divided into two routes, which are respectively connected to the three air distribution pipelines in the high-temperature reaction device 1 (when the second air distribution pipeline scheme is adopted), and the oxygen is respectively input into the primary air distribution pipeline 13, the secondary air distribution pipeline 14 and the tertiary air distribution pipeline 15 according to the set oxygen enrichment flow rate.

[0067] (II) Waste heat recovery device 2

[0068] like Figure 4 As shown, the waste heat recovery device 2 is arranged in a one-to-one correspondence with the cracking furnace 11, including: a waste heat boiler body 21, a steam drum 22 and a boiler water booster pump 23. The waste heat boiler body 21 adopts a water tube boiler form, and a radiation section 210, a superheating section 211 and an evaporation section 212 are sequentially arranged in the waste heat boiler body 21 from the inlet to the outlet, and the steam drum 22 has a saturated water outlet 221, a saturated steam outlet 222, and a gas-liquid mixture inlet 223.

[0069] Preferably, the steam drum 22 is a cylindrical structure and is located at the top of the waste heat boiler. The inlet and outlet of the steam drum 22 are respectively connected to the heat exchange devices in the radiation section 210, the superheating section 211 and the evaporation section 212 through steam-water pipelines. The boiler water (and steam) enters the heat exchange devices in each section respectively to exchange heat with the high-temperature flue gas. The heated saturated steam / water mixture returns to the steam drum 22, and liquid-vapor separation is performed in the steam drum 22.

[0070] The steam drum 22 also has a boiler water inlet 220 , through which boiler water directly enters the steam drum 22 to provide cooling medium for the heat exchange devices in each section of the waste heat boiler body 21 .

[0071] The connection structure between the radiation section 210, the superheating section 211 and the evaporation section 212 and the steam drum 22 is described below in conjunction with a specific heat exchange device:

[0072] The radiation section 210 is a cavity structure. A water-cooled wall tube panel is provided on the inner wall of the waste heat boiler body 21 where the radiation section 210 is located. The inlet and outlet of the water-cooled wall tube panel are respectively connected to the saturated water outlet 221 and the gas-liquid mixture inlet 223. The boiler water stored in the steam drum 22 flows into the water-cooled wall tube panel, absorbs the heat of the flue gas flowing through the radiation section 210, reduces the flue gas temperature, ensures that the molten salt in the flue gas solidifies into powdery dust, prevents the molten salt from adhering to the heat exchange tube, causing corrosion and blockage of the heat exchange tube, and affecting the heat exchange efficiency. The boiler water absorbs heat and is converted into saturated steam and returns to the steam drum 22 through the gas-liquid mixture inlet 223. After heat exchange, the flue gas temperature at the outlet of the radiation section 210 is 550-700°C.

[0073] The above-mentioned superheating section 211 and evaporation section 212 are both provided with a light tube heat exchanger, wherein the light tube heat exchanger of the superheating section 211 preferably adopts a U-shaped light tube structure, and the inlet of the light tube heat exchanger is connected to the saturated steam outlet 222. The saturated steam from the drum 22 exchanges heat with the high-temperature flue gas, and the saturated steam is heated to superheated steam of a specific specification, further reducing the flue gas temperature, and the superheated steam is sent to a designated receiving position outside the device through the outlet. After heat exchange, the flue gas temperature at the outlet of the evaporation section 212 is 250-350°C.

[0074] The light tube heat exchanger of the evaporation section 212 preferably adopts a U-shaped light tube or fin tube structure. The inlet of the light tube heat exchanger is connected to the saturated water outlet 221 through the boiler water booster pump 23, and the outlet is connected to the gas-liquid mixture inlet 223.

[0075] A portion of the saturated water from the drum 22 is pressurized and flows into the bare tube heat exchanger of the evaporation section 212, where it exchanges heat with the flue gas. After the saturated water is heated to a gas-liquid mixed state, it returns to the drum 22 through the gas-liquid mixture inlet 223 for liquid-gas separation. In the drum 22, the separated steam merges with the steam returned from the radiation section 210, and then enters the superheating section 211 together for superheating. Such a forced circulation mechanism ensures the flow of boiler water inside the waste heat boiler, ensures that the corner welds of the furnace tubes in the waste heat boiler design are located outside the furnace body, avoids the risk of the corner welds being corroded by acid in the furnace, and extends the operation cycle of the waste heat boiler.

[0076] The high-temperature flue gas from the high-temperature reaction device 1 exchanges heat with boiler water or steam through the radiation section 210, the superheating section 211 and the evaporation section 212 in sequence, and the cooled flue gas enters the downstream rapid cooling purification device 3.

[0077] In some embodiments, the waste heat recovery device 2 also includes: a plurality of cleaning devices 24, and a cleaning device 24 is provided at the waste heat boiler body 21 corresponding to the radiation section 210, the superheating section 211 and the evaporation section 212, for removing impurities inside the waste heat boiler body 21. The cleaning device 24 includes but is not limited to shock wave soot blowing, steam soot blowing, mechanical vibration and the like, or multiple soot blower forms are used simultaneously, preferably mechanical vibration or shock wave soot blowing.

[0078] (III) Rapid cooling and purification device 3

[0079] like Figure 5 As shown, the quench purification device 3 and the waste heat recovery device 2 are also arranged one by one, including a venturi scrubber 31, a washing spray pipeline 37 and a quench device, and the quench device includes a quench tower 32, a cooling circulation pipeline 33, a buffer tank 34 and a circulating liquid cooler 36. Specifically:

[0080] The venturi scrubber 31 includes a flue gas inlet 310, a reduced diameter section 311, a throat diameter 312, an expanded diameter section 313, a settling section 314 and a conical bottom 315 from top to bottom. The flue gas inlet 310 is connected to the outlet of the waste heat boiler body 21. The quenching tower 32 is provided with a gas-liquid separation section, a liquid collector 320, a packing layer 322, a spray layer 323 and a demister 324 from bottom to top. The gas-liquid separation section is connected to the settling section 314 of the venturi scrubber 31 through a flue gas duct 316, and the liquid collector 320 is a liquid collecting tray equipped with a steam lifting cap. The flue gas rises to the packing layer 322 through the steam lifting cap. Layer 322 contacts with the spray liquid, the falling spray liquid is collected by the liquid collecting tray and sent to the cooling circulation pipeline 33 through the liquid collecting pipe 321. The cooling circulation pipeline 33 is provided with a buffer tank 34, a quenching tower circulation pump 35 and a circulating liquid cooler 36. The buffer tank 34 is connected with the outlet of the collector 320 to store the spray liquid collected by the collector 320. The circulating liquid cooler 36 is used to cool the spray liquid. The outlet of the cooling circulation pipeline 33 is connected with the spray layer 323. The cooled spray liquid is pressurized by the quenching tower circulation pump 35 and then re-enters the quenching tower 32 for circulating spraying.

[0081] The tower bottom of the quench tower 32 is connected to the conical bottom 315 of the venturi scrubber 31 through the scrubbing spray pipeline 37, and is connected to the flue gas inlet 310 and the expansion section 313. The tower bottom liquid and the liquid phase in the conical bottom 315 are used as scrubbing liquid to first spray the flue gas passing through the flue gas inlet 310. The flue gas contacts the scrubbing liquid to form a liquid film on the gas-liquid contact surface. Then the flue gas enters the throat 312, and the flow rate increases to ensure that the flue gas has sufficient kinetic energy, so that the gas and liquid are quickly mixed and turbulent. Under the action of the drag force on the gas-liquid contact surface, the liquid phase is atomized to form small droplets, which collide with the gas phase. The rapid cooling and purification equipment can quickly cool down, wash and break the aerosol absorption of SO3, thereby reducing the risk of subsequent equipment corrosion. At the same time, a certain amount of washing liquid is also sprayed into the expansion section 313, thereby forming a liquid phase coverage area in the expansion section 313 and the sedimentation section 314. In this area, small liquid droplets further contact and collide with the gas phase, thereby achieving further rapid cooling and washing of the gas phase. Subsequently, the flue gas enters the gas-liquid separation section of the rapid cooling tower 32 through the horizontal flue gas duct 316, continues to rise through the liquid collector 320, flows through the packing layer 322 and the spray layer 323, and is finally discharged after being defogged by the demister 324.

[0082] Preferably, the buffer tank 34 is also provided with an overflow port 340 in the middle in the vertical direction, and the overflow port 340 is connected to the bottom of the quenching tower 32, and the excess spray liquid in the circulation tank enters the bottom of the tower and enters the washing spray pipeline together with the bottom liquid as washing liquid.

[0083] Preferably, a washing booster pump 38 is also provided on the washing spray pipeline 37 for pressurizing the washing liquid.

[0084] Preferably, the washing spray pipeline 37 is also connected to the acidic water treatment equipment, and the remaining liquid phase except for that used for spraying the flue gas is sent to the acidic water treatment equipment for treatment.

[0085] The flue gas treatment unit includes a secondary cooling device, a demisting device and an absorption drying device which are sequentially connected to the outlet of the above-mentioned quenching purification device to perform secondary cooling, dehydration, demisting and dehydration on the purified flue gas discharged from the quenching purification device. Specifically:

[0086] (IV) Secondary cooling device 4

[0087] like Figure 6 As shown, the secondary cooling device 4 includes: a cooling tower 41, a cooler 42 and a cooling tower circulating pump 43. A spray device and a packing layer are arranged in the cooling tower 41. When two sets of waste liquid treatment units are arranged, the purified flue gas discharged from the two quenching towers 32 are collected and enter the cooling tower 41 together. The purified flue gas contacts the low-temperature coolant in the cooling tower 41 in reverse direction to achieve deep cooling. After the circulating liquid of the cooling tower 41 is cooled, the flue gas temperature in the tower is reduced, and the saturated water in the flue gas is precipitated as the temperature decreases, thereby reducing the water content in the flue gas and achieving dehydration.

[0088] The bottom of the cooling tower 41, the cooler 42 and the spraying device are connected by pipelines. A part of the bottom liquid (cooling liquid) of the cooling tower 41 is pressurized by the cooling tower circulation pump 43 and sent to the cooler 42 for cooling, and then returns to the cooling tower 41 for spraying, and the other part is sent to the acidic water treatment equipment together with the acid bottom liquid discharged from the above-mentioned rapid cooling purification device 3.

[0089] The above-mentioned cooler 42 also has a cooling water inlet and a cooling water return port. The cooling water continuously flows in the cold side flow channel of the cooler 42 through the inlet and the return port to absorb the heat of the coolant in the hot side flow channel.

[0090] (V) Demisting device 5

[0091] like Figure 6 As shown, the demister 5 includes a plurality of demisters 51, the inlet of the demister 51 is connected to the outlet of the cooling tower 41, the outlet of the demister 51 is connected to the downstream drying device, and the plurality of demisters 51 can be selectively arranged in series or in parallel.

[0092] The demister 5 further comprises: a water sealer 52 , the gas phase pipeline of the water sealer 52 is connected with the outlet of the demister 51 , and the pressure stability in the system is ensured by controlling the liquid level in the water sealer 52 .

[0093] (VI) Absorption drying device 6

[0094] like Figure 6As shown, the absorption drying device 6 includes a drying tower 61, a cooling sulfuric acid circulation pipeline 62, and an acid cooler 63 and a circulating acid pump arranged on the cooling sulfuric acid circulation pipeline 62. The acid cooler 63 can cool the circulating liquid in the cooling sulfuric acid circulation pipeline 62.

[0095] The outlet of the demisting device 5 is connected to the inlet of the drying tower 61, and the purified flue gas after demisting is sent to the drying tower 61 for dewatering.

[0096] The bottom of the drying tower 61 is connected to the circulating liquid inlet at the top of the drying tower 61 through a cooling sulfuric acid circulation pipeline 62. The bottom liquid containing sulfuric acid is cooled by an acid cooler 63 on the sulfuric acid circulation pipeline, and returns to the drying tower 61 after being pressurized by a circulating acid pump, and is reversely contacted with the rising purified flue gas to absorb moisture in the purified flue gas. The dried purified gas enters a conventional downstream conversion absorption device through a booster fan 7 to produce sulfuric acid products.

[0097] Furthermore, the absorption drying device 6 also includes: an acid storage tank 64 arranged on the cooling sulfuric acid circulation pipeline 62 between the bottom of the drying tower 61 and the acid cooler 63. The acid storage tank 64 can store the bottom liquid of the drying tower 61, and at the same time, can also provide the bottom liquid for mixing with high-concentration sulfuric acid input from the outside.

[0098] In some embodiments, the system further comprises an oxygen input device disposed between the demister 5 and the drying device for adding oxygen to the undried purified flue gas to adjust the molar ratio of O2 and SO2 in the purified flue gas.

[0099] In summary, the operation process of the system is briefly described as follows:

[0100] The sulfuric acid (salt)-containing waste liquid from the upstream unit includes but is not limited to ammonium sulfate waste liquid from the acrylonitrile main unit, waste acid water from the MMA unit, sulfuric acid solution, alkylation waste acid from the alkylation unit and other waste liquids.

[0101] The waste liquid is transported to two independently operated waste liquid treatment units through their respective waste liquid pipelines, and is first atomized by air before entering the reduction section 110 of the cracking furnace 11. The room temperature air is preheated by the air preheating device 17, and then evenly mixed with oxygen by the oxygen control distributor to form oxygen-enriched air, and is divided into primary air, secondary air, and tertiary air to enter the burner, the reduction section 110 and the oxidation section 111 of the cracking furnace 11 respectively. The fuel and the primary air are mixed and heated by the burner and then enter the reduction section 110 of the cracking furnace 11, and a high-temperature thermal oxidation reaction occurs to release a large amount of heat, which provides heat for the reaction in the reduction section 110. The above-mentioned sulfate-containing waste liquid atomized by air is mixed with the secondary air in the reduction section 110 and undergoes cracking and high-temperature thermal oxidation reactions to convert sulfur-containing and nitrogen-containing compounds and other organic matter into CO, CO2, N2, SO2, H2O, a small amount of SO3, NO xThe flue gas then enters the oxidation section 111, where the unreacted organic matter and CO in the flue gas further react with the tertiary air supply to generate CO2, N2, SO2, and H2O, and a small amount of SO2 will react to generate SO3. By controlling the ratio of the primary air supply, the secondary air supply, and the tertiary air supply, adjusting the temperature and excess air coefficient of different areas of the cracking furnace 11, and providing sufficient residence time, the complete reaction in the cracking furnace 11 can be ensured, and the loss of SO2 and NO can be reduced. x The production of.

[0102] The main reaction equation is as follows:

[0103] Cleavage reaction:

[0104] (NH 4)2 SO4→NH3+SO2+H2O

[0105] NH4HSO4→NH3+SO2+H2O

[0106] H2SO4→H2O+SO2+O2

[0107] Oxidation reaction:

[0108] SO2+O2→SO3

[0109] NH3+O2→H2O+N2+NO x

[0110] C m H n N x O y +O2→H2O+N2+NO x +CO2

[0111] The high-temperature flue gas after the reaction contains a small amount of SO3, NOx and metal salts, which directly enter the waste heat boiler for waste heat recovery. The high-temperature flue gas exchanges heat with the boiler water in the water-cooled wall tube screen in the radiation section 210, and the flue gas temperature is reduced to 550-700°C through the heat absorption of the boiler water, ensuring that the molten salt in the flue gas solidifies into powdery dust, preventing the molten salt from adhering to the heat exchange tube, causing corrosion of the heat exchange tube, and affecting the heat exchange efficiency. Subsequently, the flue gas flows through the hot section 211 and the evaporation section 212 in sequence, further cooling down and heating the saturated steam into medium-pressure superheated steam. The flue gas temperature at the outlet of the waste heat boiler is reduced to 250-350°C, ensuring that the temperature of the flue gas and the heat exchange tube wall in the waste heat boiler is higher than the dew point temperature of the flue gas, preventing equipment corrosion. At the same time, according to the pressure drop of the waste heat boiler and the flue gas outlet temperature, the ash cleaning operation is carried out regularly to prevent the corrosion of the heat exchange tube and ensure the long-term stable operation of the waste heat boiler.

[0112] The high-temperature flue gas from the outlet of the waste heat boiler first enters the venturi scrubber 31 of the quenching purification device 3, enters from the flue gas inlet 310 of the venturi scrubber 31, and is sprayed by the reduced diameter section 311 and the expanded diameter section 313 to achieve rapid cooling, dust removal, and aerosol absorption of SO3. Then it enters the bottom of the quenching tower 32, contacts the falling spray liquid in reverse direction, and achieves further rapid cooling and washing. After being defogged by the demister 324, it is discharged from the top of the tower. The kettle liquid of the quenching tower 32 is mixed with the liquid phase discharged from the bottom of the cone of the venturi scrubber 31 and then pressurized by the venturi circulation pump. A part of the pressurized liquid phase is sprayed from the flue gas inlet 310 and the expanded diameter section 313 of the venturi scrubber 31 to circulate and spray the high-temperature flue gas. The remaining liquid phases of the two sets of quenching purification devices 3 are collected and sent to the acidic water treatment equipment for recycling.

[0113] The purified flue gas from the tops of the two quenching towers 32 is collected and enters a flue gas treatment unit, first entering the secondary cooling device 4 for cooling, and the cooled purified flue gas is sent to the demisting device 5 for demisting, and then enters the drying absorption device, and uses high-concentration sulfuric acid to absorb moisture in the purified flue gas. The dried purified flue gas is pressurized by the booster fan 7 and then enters the conversion absorption unit to produce sulfuric acid.

[0114] Example 2

[0115] On the basis of Example 1, the present invention also provides a method for treating sulfate-containing waste liquid using the above system. The specific structure of the above system is not repeated here. The sulfate-containing waste liquid from the upstream is transported to two waste liquid treatment units for high-temperature thermal reaction, and the generated flue gas is rapidly cooled and washed after waste heat utilization. The purified flue gas discharged from each waste liquid treatment unit is collected and then enters the flue gas treatment unit for secondary cooling, drying and dehydration, and finally enters the downstream conversion absorption device to produce sulfuric acid. The specific steps and process parameters are as follows:

[0116] (1) Combustion reaction: Normal temperature air is heated to 300-700° C. by air preheating device 17. The preheated air is evenly mixed with oxygen in oxygen enrichment control distributor 18, so that the oxygen content of oxygen-enriched air entering cracking furnace 11 is 22%-75%. Then, oxygen-enriched air is evenly divided into two streams and enters two cracking furnaces 11 respectively. If the second air distribution pipeline scheme is adopted, oxygen-enriched air is divided into primary air distribution, secondary air distribution and tertiary air distribution before entering each cracking furnace 11, and enters burner 12, reduction stage 1 through three air distribution pipelines respectively. 10 and oxidation section 111, the flow ratio of primary air distribution: secondary air distribution: tertiary air distribution is controlled by the regulating valve on the air distribution pipeline to be (5-8): (1-3): (1-2); if the scheme 1 of the air distribution pipeline is adopted, the oxygen-enriched air is divided into secondary air distribution and tertiary air distribution before entering each cracking furnace 11, and enters the reduction section 110 and oxidation section 111 respectively through two air distribution pipelines, and the flow ratio of secondary air distribution: tertiary air distribution is controlled by the regulating valve on the air distribution pipeline to be (6-9): (1-4). The following takes scheme 2 as an example:

[0117] At the same time, the fuel reacts with the primary air supply in the burner 12 to generate flames, releasing a large amount of heat, heating the reduction section 110 of the cracking furnace 11 to 900°C-1400°C, and the sulfate-containing waste liquid (ammonium sulfate waste liquid of the acrylonitrile device, waste acid water and waste acid water of the MMA device) is respectively input into the waste liquid treatment unit through their respective waste liquid pipelines (ammonium sulfate waste liquid pipeline, MMA waste acid water pipeline, waste acid water pipeline), atomized into small droplets and then enter the reduction section 110 of the cracking furnace 11 to be evenly mixed with the secondary air supply and react at high temperature, and ensure that the residence time of the flue gas in the reduction section 110 is 2-4s, converting sulfur-containing and nitrogen-containing compounds and other organic matter into CO, CO2, N2, SO2, H2O, a small amount of SO3, NO x As well as unreacted organic matter, preferably, the above-mentioned atomization medium is generally selected from compressed air or steam, and the atomized liquid phase is easier to be completely oxidized.

[0118] Then the flue gas enters the oxidation section 111, and the unreacted organic matter and CO in the flue gas further react with the oxygen in the tertiary air distribution to generate CO2, N2, SO2, H2O, and a small amount of SO2 will react to generate SO3. The temperature in the oxidation section 111 is 800-1200°C, preferably 900-1100°C, and the residence time of the flue gas in the oxidation section 111 is 2-6s. By controlling the flow rate of the tertiary air distribution, the oxygen content in the flue gas in the oxidation section 111 is 1%-6% mol, preferably 1.2%-2.5% mol, to ensure complete reaction.

[0119] (2) Waste heat utilization: The high-temperature flue gas discharged from the oxidation section 111 directly enters the waste heat boiler body 21 in the waste heat recovery unit, and flows through the radiation section 210, the superheating section 211 and the evaporation section 212 in the waste heat boiler body 21 in sequence. A part of the boiler water in the drum 22 enters the water-cooled wall tube panel of the radiation section 210 to exchange heat with the high-temperature flue gas, cooling the flue gas to 550-700°C. The remaining boiler water is pressurized by the boiler water booster pump 232 and enters the bare tube heat exchanger of the evaporation section 212 to exchange heat with the flue gas. The flue gas temperature at the outlet of the waste heat boiler body 21 is reduced to 250-350°C and then enters the rapid cooling purification device 3. The temperature of the flue gas and the heat exchange tube wall in the waste heat boiler body 21 is higher than the dew point temperature of the flue gas to prevent equipment corrosion. The saturated steam / water gas-liquid mixture generated by the radiation section 210 and the evaporation section 212 is returned to the steam drum 22 for liquid-gas separation. The saturated steam directly enters the bare tube heat exchanger of the superheating section 211 and is heated by the flue gas to medium-pressure superheated steam and sent out of the waste heat boiler body 21.

[0120] The waste heat recovery system effectively reduces the flue gas temperature and increases the economic benefits of the system. The molten metal salt in the high-temperature flue gas is fully cooled to solid powder in the radiation section 210 to prevent it from adhering to the outer wall of the heat exchange tube when entering the superheating section 211. At the same time, the dust removal device 24 is opened regularly to clean the metal salt adhering to the heat exchange tube from the tube wall, which can effectively prevent the heat exchange efficiency from deteriorating or the tube wall from corrosion caused by dust accumulation, and improve the equipment operation cycle.

[0121] (3) Rapid cooling and washing: The flue gas discharged from the waste heat boiler body 21 enters the rapid cooling and purification device 3, first enters the Venturi scrubber 31 from the flue gas inlet 310, and passes through the reduced diameter section 311, the throat diameter 312, the expanded diameter section 313, and the sedimentation section 314 in sequence. At the flue gas inlet 310, it contacts with the washing spray liquid. The ratio of the spray amount of the washing spray liquid to the evaporation amount is 7 to 14, preferably 8 to 12, to ensure that a liquid film is formed on the gas-liquid contact surface to protect the equipment from corrosion. Then the gas phase enters the reduced diameter section 311, the flow rate is accelerated, and the flow rate at the throat diameter 312 reaches 35 to 100 m / s, preferably 45 to 80 m / s, to ensure that the flue gas has sufficient kinetic energy, so that the gas and liquid are quickly mixed and turbulent. Under the action of the drag force on the gas-liquid contact surface, the liquid phase is atomized to form small droplets, which collide and contact with the gas phase, thereby achieving rapid cooling, washing and breaking the aerosol absorption of SO3, reducing the risk of subsequent equipment corrosion.

[0122] At the same time, a certain amount of washing spray liquid is sprayed into the expansion section 313, and a liquid phase coverage area is formed in the expansion section 313 and the sedimentation section 314. The liquid phase spray density is 40-120m 3 / (m 2 h), preferably 50 to 90 m 3 / (m 2h). The flue gas flows into the liquid phase coverage area formed by the expansion section 313 and the settling section 314, and further contacts and collides with the liquid phase droplets, further realizing rapid cooling and washing of the gas phase.

[0123] Then the flue gas enters the lower part of the quench tower 32 through the horizontal flue gas duct 316, and passes through the gas-liquid separation section, the steam riser cap, and the packing layer 322 from bottom to top. The flue gas is effectively cooled and purified in the process of being fully contacted with the spray liquid sprayed down from the spray layer 323 at the packing layer 322. Then, the flue gas continues to rise, passes through the demister 324 to remove the residual droplets in the flue gas, and finally escapes from the top of the tower.

[0124] The spray liquid collected by the liquid collecting tray is sent to the buffer tank 34 through the liquid collecting pipe 321. A part of the spray liquid in the buffer tank 34 returns to the gas-liquid separation section through the overflow port 340, and then flows out from the bottom of the quenching tower 32. After mixing with the liquid phase discharged from the conical bottom 315 of the venturi scrubber 31, it is pressurized by the washing booster pump 38. A part of the pressurized liquid phase is sprayed into the flue gas inlet 310 of the venturi scrubber 31, and the other part is sprayed into the flue gas from the expansion section 313 to quench and wash the high-temperature flue gas. The remaining liquid phase is collected and sent to the acidic water treatment equipment for recycling.

[0125] The other part of the spray liquid in the buffer tank 34 is sent to the circulating liquid cooler 4236 through the quench tower circulation pump 35, and after being cooled to 35-50° C., it returns to the spray layer 323 to realize circulating spraying.

[0126] (4) Secondary cooling: The purified flue gas at the top of the two quenching towers 32 is collected and then enters a set of secondary cooling device 4 to deeply cool the purified flue gas. The purified flue gas first enters from the bottom of the cooling tower 41 and contacts with the low-temperature coolant in reverse direction to be cooled and dehydrated. The cooled purified flue gas enters the downstream demisting device 5.

[0127] After the kettle liquid (cooling liquid) of the cooling tower 41 is pressurized by the cooling tower circulation pump 43, a part of the circulating liquid is sent to the cooler 42 to be cooled to 20-40°C and then returned to the cooling tower 41, and the other part of the cooling liquid is mixed with the discharged acidic water of the above-mentioned two sets of rapid cooling and purification devices 3 and then sent to the acidic water treatment equipment for recycling.

[0128] (5) Demisting: After secondary cooling, the purified flue gas carries a large amount of acid droplets and a small amount of fine dust particles, which are further removed by entering the demisting device 5. The demisting device 51 is preferably a wet electrostatic demisting device 51, and one or more demisting devices 51 are connected in parallel or in series to ensure that the removal efficiency of acid mist and dust is ≥ 99.5%. Figure 2 and 6Shown are two demisters 51 connected in series, the inlet of the first demister 51 is connected to the outlet of the upstream cooling tower 41, and the outlet of the last demister 51 is connected to the gas phase pipeline of the water sealer 52. By controlling the liquid level in the water sealer 52, the pressure stability in the system is ensured.

[0129] (6) Absorption drying: The purified flue gas from the demisting device 5 is mixed with a certain amount of air at room temperature and then enters the absorption drying device 6. In the mixed gas formed by the purified flue gas and air, the molar ratio of oxygen to SO2 is 0.8 to 2, preferably 0.9 to 1.3, which can ensure that SO2 can be completely converted into SO3 in the subsequent sulfuric acid preparation.

[0130] The mixed gas enters from the bottom of the drying tower 61, and the water in the purified gas is absorbed by concentrated sulfuric acid with a concentration of 92% to 98%, ensuring that the water content of the purified gas at the top of the tower is ≤100mg / Nm 3 The dried purified gas enters the downstream conventional conversion absorption device through the booster fan 7. The molar ratio of O2 to SO2 in the purified flue gas discharged from the booster fan 7 is 0.8 to 2, preferably 0.9 to 1.3, and the water content is ≤100 mg / Nm 3 , SO2 concentration is 2.5%~14%mol, dust content ≤1.2mg / Nm 3 , acid mist concentration <5mg / Nm 3 , can be used to produce 98% sulfuric acid, 100% sulfuric acid and nicotinic acid products.

[0131] The kettle liquid of the drying tower 61 enters the acid storage tank and mixes with a high-concentration sulfuric acid liquid to make the concentrated sulfuric acid concentration in the acid storage tank 92% to 98%wt. After being pressurized by the circulating acid pump, it enters the acid cooler 63 for heat exchange with the circulating cooling water, and the concentrated sulfuric acid is cooled to 30 to 60°C and returned to the drying tower 61 to ensure the absorption efficiency of moisture in the flue gas. At this time, the top gas phase temperature of the drying tower 61 is ≤60°C, the kettle temperature is ≤75°C, and the difference between the acid concentration at the kettle outlet and the circulating acid concentration at the inlet is less than 0.5%wt.

[0132] The system and method for resource-based treatment of sulfate-containing wastewater provided by the present invention are further described in detail below in conjunction with specific embodiments.

[0133] Example 3

[0134] On the basis of Examples 1 and 2, the ammonium sulfate waste liquid and MMA waste acid water from the upstream device in this embodiment are composed as follows:

[0135] Ammonium sulfate waste liquid composition Mass fraction % MMA waste acid water composition Mass fraction % Ammonium sulfate 38.0 sulfuric acid 17.4 water 47.49 water 24.0 Heavy components 14.5 Ammonium bisulfate 53.0 Acrylonitrile 0.01 Methacrylic acid 0.19 Acetonitrile 0 Acetone disulfonate 4.13 Methanol 0.19 Methyl Methacrylate 0.75 dimethyl ether 0.34 Mass flow kg / h 29916 Mass flow kg / h 60275

[0136] Two streams of sulfate-containing waste liquids enter the two waste liquid treatment units in Example 1 respectively. In each waste liquid treatment unit, 14958 kg / h of ammonium sulfate waste liquid from an acrylonitrile device, 30137.5 kg / h of MMA waste acid water, and 2250 kg / h of 98% waste sulfuric acid liquid enter the top of the L-shaped cracking furnace 11 and the reduction section 110 through the ammonium sulfate waste liquid pipeline, the MMA waste acid water pipeline, and the acid water pipeline, respectively. Methane is used as fuel and directly enters the burner at the top of the cracking furnace 11. The atomizing medium is compressed air. After being preheated to 510°C by the air preheating device 17, the room temperature air is mixed with room temperature oxygen. The oxygen content of the mixed oxygen-enriched air is 30% and the temperature is 450°C. It is divided into three times and enters the cracking furnace 11. The flow ratio of the primary air supply: the secondary air supply: the tertiary air supply is 7:2:1. At this time, the temperature of the reduction section 110 is 1100°C, the residence time of the flue gas in the reduction section 110 is 2.2s, the temperature of the oxidation section 111 is 1065°C, the residence time is 4.4s, and the oxygen content in the flue gas is 1.5%, which ensures that the organic matter is completely reacted and reduces the loss of SO2 and NO x Generation of.

[0137] Then the flue gas enters the waste heat boiler body 21. By controlling the boiler water intake, steam production and the liquid level in the drum 22, the temperature of the flue gas after passing through the radiation section 210 is ensured to be about 650°C, the flue gas temperature at the outlet of the waste heat boiler is 320°C, and 98.4t / h of superheated steam at 4.2MPaG and 390°C is produced as a by-product. The radiation section 210 of the waste heat boiler uses water-cooled wall tube screens, the superheat section 211 and the evaporation section 212 use U-shaped light tubes, and the cleaning device 24 uses shock wave soot blowing to prevent the heat exchange tube from accumulating soot and causing equipment corrosion and poor heat exchange efficiency.

[0138] The flue gas at the outlet of the waste heat boiler enters the venturi scrubber 31, and the ratio of the spray amount of the circulating scrubbing liquid to the evaporation amount at the flue gas inlet 310 is controlled to be 9, the flue gas flow rate at the throat diameter 312 is 63m / s, and the liquid phase spray density in the liquid phase coverage area of ​​the expansion section 313 and the settling section 314 is 55-82m 3 / (m 2 h), at which time the flue gas temperature at the outlet of the venturi scrubber 31 is 83°C, and the flue gas enters the bottom of the quenching tower 32, where it contacts the spray liquid in reverse direction to achieve further quenching and washing, and the temperature of the purified flue gas at the outlet of the top of the quenching tower 32 is reduced to 40°C.

[0139] The purified gases at the outlets of the two quench purification devices 3 are collected and sent to a flue gas treatment unit, first to the bottom of the cooling tower 41, and then to the defogger 5 after being further cooled to 30°C. The acid water discharged from the two quench purification devices 3 and the cooling device is 75t / h in total, and is sent to the acid water treatment equipment for recycling.

[0140] The purified flue gas from the secondary cooling device 4 enters the electrostatic precipitator 324. This system is equipped with 4 electrostatic precipitators 324, which are connected in series and then in parallel. The removal efficiency of acid mist and dust is 99.8%.

[0141] Then the purified gas enters the absorption and drying device 6, and the drying tower 61 uses 96%wt concentrated sulfuric acid to absorb the moisture in the purified gas. After the 96%wt concentrated sulfuric acid is pressurized by the circulating acid pump, it enters the acid cooler 63 to cool the circulating sulfuric acid to 50°C and returns to the drying tower 61 to absorb the moisture in the purified flue gas. At this time, the gas phase temperature at the top of the drying tower 61 is 50°C, the tower bottom temperature is 59.9°C, and the acid concentration at the tower bottom outlet is 95.6%wt. A stream of 98%wt sulfuric acid is added to the acid storage tank and mixed with the drying tower 61 bottom liquid to ensure that the circulating acid concentration in the acid storage tank is 96%wt.

[0142] After the dried purified flue gas is mixed with the air at room temperature, the air flow rate is controlled so that the molar ratio of O2 to SO2 in the mixed gas discharged by the booster fan 7 is 1 and the water content is 82 mg / Nm 3 , dust content is 1mg / Nm 3 , acid mist concentration is 4mg / Nm 3 At this time, the SO2 concentration in the purified gas is 8.06% mol, and it enters the subsequent conversion and absorption equipment to produce about 400,000 tons / year of sulfuric acid (calculated as 100% sulfuric acid).

[0143] Example 4

[0144] On the basis of Examples 1 and 2, the waste liquid containing sulfuric acid (salt) from the upstream device in this example is composed as follows:

[0145]

[0146] The three waste liquids in the table enter the two waste liquid treatment units in Example 1 respectively. In each waste liquid treatment unit, the ammonium sulfate waste liquid from the acrylonitrile device is 23859 kg / h, the MMA waste acid water is 14964 kg / h, and the alkylation waste acid is 4115 kg / h. They enter the top of the L-shaped cracking furnace 11 and the reduction section 110 through the ammonium sulfate waste liquid pipeline, the MMA waste acid water pipeline and the acid water pipeline respectively. Methane is used as fuel and directly enters the burner at the top of the cracking furnace 11. The atomizing medium is compressed air. After being preheated to 730°C by the air preheating device 17, the room temperature air is mixed with room temperature oxygen. The oxygen content of the mixed oxygen-enriched air is 50% and the temperature is 650°C. It is divided into three times and enters the cracking furnace 11. The flow ratio of the first air supply: the second air supply: the third air supply is 7:2:1. At this time, the temperature of the reduction section 110 is 1065°C, the residence time of the flue gas in the reduction section 110 is 2.5s, the temperature of the oxidation section 111 is 1065°C, the residence time is 4.2s, and the oxygen content in the flue gas is 1.5%, which ensures that the organic matter is completely reacted and reduces the loss of SO2 and NO x Generation of.

[0147] Then the flue gas enters the waste heat boiler body 21. By controlling the boiler water intake, steam production and the liquid level in the drum 22, the temperature of the flue gas after passing through the radiation section 210 is ensured to be about 670°C, the flue gas temperature at the outlet of the waste heat boiler is 315°C, and 73.4t / h of superheated steam at 400°C is produced as a by-product. The radiation section 210 of the waste heat boiler uses water-cooled wall tube screens, the superheat section 211 and the evaporation section 212 use U-shaped light tubes, the radiation section 210 of the waste heat boiler uses a mechanical vibration cleaning method, and the superheat section 211 and the evaporation section 212 both use shock wave soot blowing to prevent the heat exchange tube from accumulating soot and causing equipment corrosion and poor heat exchange efficiency.

[0148] The flue gas at the outlet of the waste heat boiler enters the venturi scrubber 31, and the ratio of the spray amount and the evaporation amount of the circulating scrubbing liquid at the flue gas inlet 310 is controlled to be 8.5, the flue gas flow rate at the throat diameter 312 is 61m / s, and the liquid phase spray density in the liquid phase coverage area of ​​the expansion section 313 and the settling section 314 is 57-84m 3 / (m 2 h), at which time the flue gas temperature at the outlet of the venturi scrubber 31 is 81°C, and the flue gas enters the bottom of the quenching tower 32, where it contacts the spray liquid in reverse direction to achieve further quenching and washing, and the temperature of the purified flue gas at the outlet of the top of the quenching tower 32 is reduced to 40°C.

[0149] The purified gases at the outlets of the two sets of quenching and purification devices 3 are collected and sent to a flue gas treatment unit, first entering the bottom of the cooling tower 41, and then further cooled to 30°C before being sent to the demisting device 5. The two sets of quenching and purification devices 3 and the secondary cooling device 4 produce a total of 54.6 t / h of acidic water, which is sent to the acidic water treatment equipment for recycling.

[0150] The purified gas from the secondary cooling device 4 enters the electrostatic precipitator 324. This system is equipped with 4 electrostatic precipitators 324, which are connected in series and then in parallel. The removal efficiency of acid mist and dust is 99.8%.

[0151] Then the purified gas enters the absorption and drying device 6, and the drying tower 61 uses 93.5%wt concentrated sulfuric acid to absorb the moisture in the purified gas. After the 93.5%wt concentrated sulfuric acid is pressurized by the circulating acid pump, it enters the acid cooler 63 to cool the circulating sulfuric acid to 50°C and returns to the drying tower 61 to absorb the moisture in the purified flue gas. At this time, the gas phase temperature at the top of the drying tower 61 is 50°C, the tower bottom temperature is 62°C, and the acid concentration at the tower bottom outlet is 92.9%wt. A stream of 99.2%wt sulfuric acid is added to the acid storage tank and mixed with the drying tower 61 bottom liquid to ensure that the circulating acid concentration in the acid storage tank is 93.5%wt.

[0152] After the dried purified flue gas is mixed with the air at room temperature, the air flow rate is controlled so that the molar ratio of O2 to SO2 in the mixed gas discharged by the booster fan 7 is 1.1 and the water content is 87 mg / Nm 3 , dust content is 1mg / Nm 3 , acid mist concentration is 4.3mg / Nm 3 At this time, the SO2 concentration in the purified gas is 10.6% mol, and it enters the subsequent conversion and absorption equipment to produce about 440,000 tons / year of sulfuric acid (calculated as 100% sulfuric acid).

[0153] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A sulfate-containing waste liquid treatment system for acrylonitrile and its combined device, characterized in that: include: An oxygen enrichment control distributor, a waste liquid treatment unit and a flue gas treatment unit, wherein at least two waste liquid treatment units are provided, and multiple waste liquid treatment units are provided in parallel, and flue gas discharged from multiple waste liquid treatment units is collected and enters the flue gas treatment unit; The waste liquid treatment unit comprises a high temperature reaction device, a waste heat recovery device and a rapid cooling purification device connected in sequence; The oxygen-enriched control distributor is used to deliver a mixed gas of air and oxygen to each of the high-temperature reaction devices; The high temperature reaction device is used to burn the sulfate-containing waste liquid with oxygen-rich gas; The waste heat recovery device is used to recover waste heat from the flue gas discharged from the high-temperature reaction device; The quenching and purification device is used to cool and wash the flue gas; The flue gas treatment unit comprises a secondary cooling device, a demisting device and an absorption drying device which are sequentially connected to the outlet of the quench purification device, and is used for performing secondary cooling, dehydration, demisting and dehydration on the purified flue gas discharged from the quench purification device.

2. The sulfate-containing wastewater treatment system according to claim 1, characterized in that: The high temperature reaction device includes a cracking furnace, a burner, and a plurality of air distribution pipelines for supplying oxygen-rich gas. The cracking furnace is used for high-temperature thermal oxidation reaction of sulfate-containing waste liquid with oxygen-rich gas, and the interior of the cracking furnace includes a reduction section and an oxidation section, and the reduction section is connected to the outlet of the burner; The burner is used to mix the oxygen-rich gas and fuel and ignite to generate flame; The arrangement of the plurality of air distribution pipelines includes scheme 1 or scheme 2: The first solution: the plurality of air distribution pipelines include at least one secondary air distribution pipeline connected to the burner or the reduction section and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the burner or the reduction section and the oxidation section respectively; The second solution: the plurality of air distribution pipelines include at least one primary air distribution pipeline connected to the burner, at least one secondary air distribution pipeline connected to the reduction section, and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the burner, the reduction section and the oxidation section respectively.

3. The sulfate-containing wastewater treatment system according to claim 1, characterized in that: The waste heat recovery device includes: a waste heat boiler body, a steam drum, a boiler water booster pump and several ash cleaning devices; The drum has a boiler water inlet, a saturated water outlet, a saturated steam outlet, and a gas-liquid mixture inlet; The waste heat boiler body is provided with a radiation section, a superheating section and an evaporation section in sequence from the inlet to the outlet. The waste heat boiler body where the radiation section is located is a cavity with a water-cooled wall tube panel on the inner wall, and the inlet and outlet of the water-cooled wall tube panel are respectively connected to the saturated water outlet and the gas-liquid mixture inlet; The superheating section and the evaporation section are both provided with a bare tube heat exchanger, the inlet of the bare tube heat exchanger of the superheating section is connected to the saturated steam outlet, and the outlet is used to output the superheated steam heated by the high-temperature flue gas; the inlet and outlet of the bare tube heat exchanger of the evaporation section are respectively connected to the saturated water outlet and the gas-liquid mixture inlet; The cleaning device is provided at the waste heat boiler body corresponding to the radiation section, the superheating section and the evaporation section, and is used to remove impurities inside the waste heat boiler body.

4. The sulfate-containing wastewater treatment system according to claim 1, characterized in that: The secondary cooling device comprises: a cooling tower and a cooler, The cooling tower is provided with a spray device and a packing layer; The bottom of the cooling tower, the cooler and the spraying device are connected through pipelines to re-spray the bottom liquid of the cooling tower after cooling it.

5. The sulfate-containing wastewater treatment system according to claim 1, characterized in that: The demisting device comprises a water sealer and a plurality of demisters, wherein the plurality of demisters are connected in series or in parallel; The water sealer is connected to the pipeline between the demister and the drying device.

6. The sulfate-containing wastewater treatment system according to claim 1, characterized in that: The absorption drying device comprises a drying tower, a cooling sulfuric acid circulation pipeline, and an acid storage tank and an acid cooler arranged on the cooling sulfuric acid circulation pipeline; The inlet of the drying tower is connected to the outlet of the demisting device; The bottom of the drying tower is connected to the circulating liquid inlet at the top of the drying tower through the cooling sulfuric acid circulation pipeline. The acid storage tank is used to mix and store the bottom liquid of the drying tower with high-concentration sulfuric acid. The acid cooler is used to cool the circulating liquid in the cooling sulfuric acid circulation pipeline.

7. The sulfate-containing wastewater treatment system according to claim 1, characterized in that: The quenching and purification device comprises: a venturi scrubber, a scrubbing spray pipeline, and a quenching device; The venturi scrubber comprises a flue gas inlet, a reduced diameter section, a throat diameter, an expanded diameter section, and a settling section from top to bottom, and the flue gas inlet is connected to the outlet of the waste heat recovery device; The quenching device comprises a quenching tower, a cooling circulation pipeline, a buffer tank and a circulating liquid cooler. The quenching tower is connected to the venturi scrubber through a flue gas pipeline. The bottom of the quenching tower is connected to the bottom of the venturi scrubber through the washing spray pipeline, and is connected to the flue gas inlet and the expansion section. The cooling circulation pipeline is used to cool the spray liquid in the quenching tower and re-input it into the quenching tower for circulation spraying; the buffer tank is connected to the quenching tower and is used to collect the spray liquid in the tower, and the circulating liquid cooler is used to cool the spray liquid; The overflow port of the buffer tank is communicated with the bottom of the quenching tower, and the overflow port is located in the middle of the buffer tank in the vertical direction.

8. A method for treating sulfate-containing waste liquid in acrylonitrile and its combined device, using the sulfate-containing waste liquid treatment system according to any one of claims 1 to 7, characterized in that: The high temperature reaction device comprises a cracking furnace and a burner, wherein a reduction section and an oxidation section are arranged inside the cracking furnace; The steps of the method are as follows: S1, the sulfate-containing waste liquid from the upstream is atomized and transported to the cracking furnace, the oxygen-rich gas and the fuel are mixed through the burner and flames are generated and then input into the reduction section, and the sulfate-containing waste liquid and the oxygen-rich gas react in the reduction section and the oxidation section in turn; The flue gas discharged from the cracking furnace enters the waste heat recovery device and the quenching purification device in sequence for waste heat recovery, quenching and washing; S2. The flue gases discharged from each of the quenching and purification devices are collected and then enter the secondary cooling device for deep cooling, and then enter the demisting device and the absorption and drying device for demisting and drying, and then are sent to the downstream conversion absorption device.

9. The method for treating sulfate-containing wastewater according to claim 8, characterized in that: The high temperature reaction device further comprises: a plurality of air distribution pipelines, and the arrangement of the plurality of air distribution pipelines comprises scheme 1 or scheme 2: The first solution: the plurality of air distribution pipelines include at least one secondary air distribution pipeline connected to the burner or the reduction section and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the reduction section and the oxidation section respectively; In the step S1, secondary and tertiary air distribution is performed to the reduction section and the oxidation section respectively according to a set oxygen enrichment flow ratio, and the set oxygen enrichment flow ratio is: Primary air distribution: Secondary air distribution = (6-9): (1-4) The second solution: The plurality of air distribution pipelines include at least one primary air distribution pipeline connected to the burner, at least one secondary air distribution pipeline connected to the reduction section, and at least one tertiary air distribution pipeline connected to the oxidation section, so as to supply the oxygen-rich gas to the burner, the reduction section, and the oxidation section respectively; In the step S1, primary air distribution, secondary air distribution and tertiary air distribution are respectively performed to the burner, the reduction section and the oxidation section according to the set oxygen enrichment flow ratio; The oxygen-rich flow ratio is set to: Primary air distribution: Secondary air distribution: Tertiary air distribution = (5-8): (1-3): (1-2) 。 10. The method for treating sulfate-containing wastewater according to claim 8, characterized in that: The temperature of the reduction section is 900-1400°C, and the residence time of the flue gas is 2-4s; The temperature of the oxidation section is 800-1200°C, and the residence time of the flue gas is 2-6s; The oxygen content of the flue gas at the outlet of the oxidation section is 1% to 6% mol; and / or, The method further comprises: before entering the absorption drying device, inputting oxygen into the purified flue gas discharged from the demisting device to adjust the molar ratio of O2 and SO2 in the purified flue gas to 0.8-2.

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