System and method for synergistically treating alkaline residue wastewater by resource utilization of waste flue gas

Abstract

The invention belongs to the technical field of wastewater and waste gas treatment, and discloses a system and a method for synergistically treating alkaline residue wastewater by resource utilization of waste flue gas. The system comprises a heating and mixing unit, a mixing and absorbing unit and a separating and recycling unit, the heating and mixing unit comprises a residue wastewater main pipeline and a waste flue gas introduction pipeline; the mixing absorption unit comprises a mixing main pipeline and a flow guide partition plate; the separation and recovery unit comprises a main body with a cylindrical side wall, and an outlet of the mixing main pipeline is communicated with the interior of the main body in a circumscribed line form; a rotating device and a wastewater recycling pipe are arranged at the bottom of the main body; a salt product recovery tank is arranged at the bottom of the side wall of the main body; an exhaust pipe is arranged at the top of the body. According to the invention, the heat energy, CO2 and SO2 of the waste flue gas are recycled while the waste flue gas and the alkaline residue wastewater are treated, the waste flue gas is recycled by the carbonization device, high-quality sodium carbonate is prepared more economically and environmentally, and the economic benefit and the environmental benefit of the carbonization device are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater and waste gas treatment, and more specifically, relates to a system and method for resourceful utilization of waste flue gas and coordinated treatment of alkali residue wastewater. Background Art

[0002] Ethylene is one of the most important chemical raw materials. The catalytic cracking process is an important process for producing ethylene in petrochemicals, but the process requires alkali liquor to flush the cracking gas, which produces a large amount of alkali residue wastewater, which becomes a serious environmental pressure for the catalytic cracking process. Due to the use of excessive alkali liquor to absorb gases such as H2S, CO and HCN in the cracking gas, the alkali residue wastewater contains a certain amount of residual NaOH and substances such as Na2S, Na2SO3, Na2S2O3 and Na2CO3, accompanied by COD of up to tens of thousands or even hundreds of thousands of mg / L, which is difficult to handle. In addition, the alkali residue wastewater produced by the alkali liquor flushing device of wet desulfurization in the coking process, the alkali liquor flushing device of flue gas desulfurization and deacidification of waste incineration power generation, and the alkali liquor flushing device of flue gas deacidification of hazardous waste incinerators also has similar properties, containing NaOH, Na2S, Na2SO3, Na2S2O3 and Na2CO3 and certain COD.

[0003] At present, domestic petrochemical enterprises mostly use incineration to treat alkali slag wastewater. While achieving COD removal, the salt substances such as Na2S, Na2SO3, Na2S2O3 and Na2CO3 in the alkali slag wastewater are converted into Na2SO4 and Na2CO3. After incineration, the incineration residue is mainly composed of Na2SO4 and Na2CO3, and contains a certain amount of NaOH and a small amount of metal salt impurities, which is a mixed salt hazardous waste. For petrochemical enterprises, outsourcing treatment is required, which seriously increases the overall treatment cost of the company's alkali slag wastewater. Low-cost treatment of the residue after the incineration of ethylene alkali slag and resource recovery of salt resources are important measures for petrochemical enterprises to reduce operating costs and improve the economy of catalytic cracking processes.

[0004] The solubility of Na2SO4 and Na2CO3 is very similar, which makes it difficult to separate the two, seriously affecting the purity of the products recovered from the two. Converting Na2CO3 into NaHCO3 through a carbonization device is a very effective means of separating Na2SO4. However, the carbonization device needs to be equipped with CO2 as the raw gas and the device itself needs to be heated, resulting in the need to improve the economic efficiency of the device. In addition, the purity of the product produced by the carbonization device is also one of the important indicators for device evaluation. The carbonization device has a need for transformation and improvement in terms of reducing the economic cost of the equipment while ensuring product quality.

[0005] CN112266003A discloses a soda ash carbonization tower for combined alkali production. It includes a base, a tower bottom, a cooling section tower body, a generating section tower body, an absorbing section tower body, a partition, a gas distribution device and a cap. The equipment needs to be equipped with additional CO2 raw gas, which is costly, and the process needs to be equipped with high-temperature raw liquid, the equipment has high heating energy consumption, and a large amount of circulating water is required for cooling, so the equipment operation cost is high.

[0006] CN115092943A discloses a method for preparing sodium bicarbonate. The raw materials used are industrial sodium hydroxide, silicon dioxide, aqueous thickener, foaming agent, and liquid carbon dioxide. The cost of raw materials is relatively high, and waste gas and waste liquid are produced after carbonization. The environmental protection and economic efficiency of the equipment process need to be improved. Summary of the invention

[0007] The carbonization device is an important equipment and tool for separating Na2SO4 and Na2CO3 from the residue after the incineration of alkali slag wastewater and recovering NaHCO3. The purpose of the present invention is to address the problems of low economic efficiency and low product quality of the current carbonization device, and to propose a system and method for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater. The present invention achieves resource utilization of the heat energy, CO2 and SO2 of the waste flue gas while treating the waste flue gas and alkali slag wastewater, realizes resource utilization of waste flue gas by the carbonization device, and prepares high-quality soda ash in a more economical and environmentally friendly manner, thereby improving the economic and environmental benefits of the carbonization device.

[0008] In order to achieve the above-mentioned object, the present invention provides a system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater, the system comprising a heating and mixing unit, a mixing and absorbing unit and a separation and recovery unit;

[0009] The heating and mixing unit comprises a residual wastewater main pipeline and a waste flue gas introduction pipeline; the waste flue gas introduction pipeline is vertically arranged on the side wall of the residual wastewater main pipeline; a swirl structure is arranged at the outlet of the residual wastewater main pipeline;

[0010] The mixing absorption unit comprises a mixing main pipeline and a guide baffle; the guide baffle is arranged on the inner wall of the mixing main pipeline; the inlet of the mixing main pipeline is connected with the outlet of the residual wastewater main pipeline through the cyclone structure;

[0011] The separation and recovery unit includes a main body with a cylindrical side wall, and the outlet of the mixing main pipeline is connected to the interior of the main body in the form of an external tangent line; a rotating device and a wastewater recovery pipe are provided at the bottom of the main body, and the rotating device is used to make the waste gas and wastewater system entering the separation and recovery unit swirl in the separation and recovery unit; a salt product recovery tank is provided at the bottom of the side wall of the main body; and an exhaust pipe is provided at the top of the main body.

[0012] In the present invention, a separate crystallization recovery tank and a wastewater recovery pipe are provided in the separation and recovery unit, so that the crystallized soda ash and the tempering waste liquid are recovered separately, thereby improving the purity of the product and the economy of the system.

[0013] According to the present invention, preferably, the heating mixing unit and the mixing absorption unit are both multiple and the number is the same, and the outlet of the mixing main pipeline of each mixing absorption unit is connected to the interior of the main body in the form of an external tangent line.

[0014] According to the present invention, preferably, in each mixed absorption unit, the structure of the guide baffle is:

[0015] A first groove is provided on one side of the guide baffle plate close to the inner wall of the main mixing pipe, the first groove and the inner wall of the main mixing pipe enclose a first flow channel, the first flow channel extends along the axial direction of the main mixing pipe, and a second flow channel is provided on one side of the guide baffle plate away from the inner wall of the main mixing pipe, the second flow channel extends along the axial direction of the main mixing pipe;

[0016] The first flow channel is gradually expanded and includes a first sub-flow channel and a second sub-flow channel sequentially arranged along the flow direction of the fluid, the axes of the first sub-flow channel and the second sub-flow channel are straight lines, and a first angle is formed between the second sub-flow channel and the first sub-flow channel;

[0017] The second flow channel is gradually expanded and includes a third sub-flow channel and a fourth sub-flow channel sequentially arranged along the flow direction of the fluid, the axis of the third sub-flow channel is an arc convex toward the center of the main mixing channel, the axis of the fourth sub-flow channel is a straight line, and the third sub-flow channel and the fourth sub-flow channel gradually approach the center of the main mixing channel along the flow direction of the fluid;

[0018] One end of the second sub-channel away from the first sub-channel is connected to one end of the fourth sub-channel away from the third sub-channel, and a second angle between the axis of the second sub-channel and the axis of the fourth sub-channel is 43°-62°.

[0019] According to the present invention, preferably, the number of the mixed absorption units is 2-10, preferably 4.

[0020] According to the present invention, preferably, in each mixed absorption unit, the number of the guide baffles is 4-14 groups, and each group has 2-6 guide baffles evenly distributed on the inner wall of the mixed main pipeline, preferably 8 groups.

[0021] According to the present invention, preferably, the distance between the top of one end of the third sub-channel away from the fourth sub-channel and the center of the mixing main pipe is 0.45-0.55 times the radius of the mixing main pipe;

[0022] The distance between the top of one end of the fourth sub-channel away from the third sub-channel and the center of the mixing main pipe is 0-0.15-0.17 times the radius of the mixing main pipe.

[0023] According to the present invention, preferably, an inclined isolation plate is further provided above the wastewater recovery pipe, and the inclined isolation plate is used to prevent crystallized salt from blocking the wastewater recovery pipe. In the present invention, the crystallized salt generally refers to crystallized soda ash.

[0024] According to the present invention, preferably, the inclined isolation plate has an inclination angle of 25-78° relative to the horizontal plane, preferably 60-75°. In the present invention, the inclination angle of the inclined isolation plate can be adjusted according to the concentration of crystallized salt, the total amount of the waste gas and wastewater system in the separation and recovery unit, and the rotation and stirring speed of the rotating device to avoid the problem of the wastewater recovery pipe being blocked by crystallized salt.

[0025] In the present invention, the outlet of the mixing main pipeline is connected to the interior of the main body in the form of an external tangent, thereby providing an initial centrifugal force for the waste gas and waste water system from the mixing absorption unit to enter the separation and recovery unit, reducing the energy consumption of the rotating device of the separation and recovery unit, and improving the economy of the system. At the same time, the number of the mixing absorption units can control and improve the balance of centrifugal force when the waste gas and waste water system enters the separation and recovery unit, enhance the carbonization treatment efficiency, and save the equipment floor space. Preferably, the number of the mixing absorption units is 4.

[0026] According to the present invention, preferably, in each heating and mixing unit, the number of the swirl structures is 1-4; preferably, when there are multiple swirl structures, the multiple swirl structures are arranged in sequence along the flow direction of the fluid at the outlet of the residual wastewater main pipeline.

[0027] According to the present invention, preferably, for each residual wastewater main pipeline, the waste flue gas introduction pipeline is one or more.

[0028] According to the present invention, preferably, the number of the waste flue gas introduction pipes is 1-8, preferably 4.

[0029] According to the present invention, preferably, when there are multiple waste flue gas introduction pipes, the multiple waste flue gas introduction pipes are vertically arranged in a ring on the side wall of the residual wastewater main pipe. The purpose of such arrangement is to improve the gas-liquid mixing in the system, and increase the hydraulic shearing effect on the waste flue gas through the annularly evenly distributed waste flue gas inlet, increase the degree of hydraulic cutting and fragmentation of the waste flue gas bubbles, and thus increase the gas-liquid contact area, thereby enhancing the carbonization reaction efficiency of the system and the waste flue gas purification efficiency.

[0030] Another aspect of the present invention provides a method for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater, the method adopts the system and comprises the following steps:

[0031] S1: the residual waste water and the waste flue gas are mixed in the heating and mixing unit in a cross-flow manner, the waste flue gas is broken under the action of hydraulic shear, the residual waste water and the waste flue gas are fully contacted and reacted, and then enter the mixing absorption unit;

[0032] S2: In the mixed absorption unit, the guide baffle is used to further strengthen the hydraulic shearing effect on the waste flue gas, and the residual waste water and the waste flue gas are further fully contacted and reacted, and then enter the separation and recovery unit;

[0033] S3: In the separation and recovery unit, the rotating device is used to cause the waste gas and wastewater system from the mixed absorption unit to swirl in the separation and recovery unit to obtain crystallized soda ash, tempered waste liquid, and purified waste flue gas. The crystallized soda ash enters the salt product recovery tank, the tempered waste liquid flows into the wastewater recovery pipe, and the purified waste flue gas is discharged from the exhaust pipe.

[0034] According to the present invention, preferably, the residual wastewater is the wastewater obtained by dissolving the residue in water after the residue is obtained by incinerating the alkali residue wastewater produced by the alkali washing device. That is to say, the present invention does not directly treat the alkali residue wastewater, but the wastewater (i.e., the residual wastewater) obtained by redissolving the residue obtained by incinerating the alkali residue wastewater. As described in the background technology part of the present invention, the residue after incineration of the alkali residue wastewater belongs to mixed salt hazardous waste, and direct treatment cannot obtain a good treatment effect. Therefore, the present invention redissolves the residue obtained by incinerating the alkali residue wastewater to obtain the residual wastewater, and then treats it. Moreover, in the present invention, compared with directly treating the alkali residue wastewater, the pH of the conditioned waste liquid obtained by the present invention is optimized (the water quality conditions of the conditioned waste liquid include: pH 7.5-8.5), so the amount of acid solution used in the subsequent recovery of sodium sulfate product salt can be saved.

[0035] According to the present invention, preferably, the alkali washing device is at least one of a device for washing acidic gases in cracking gas during catalytic cracking, an alkali liquid washing device for wet desulfurization in a coking process, an alkali liquid washing device for desulfurization and deacidification of flue gas from waste incineration power generation, and an alkali liquid washing device for deacidification of flue gas from a hazardous waste incinerator.

[0036] According to the present invention, preferably, the water quality conditions of the residual wastewater include: pH 8-12, Na2SO4 concentration 300-470g / L, Na2CO3 concentration 320-460g / L, metal element concentration 0.001-0.010g / L, NaOH concentration 0-0.030g / L.

[0037] According to the present invention, preferably, the waste flue gas is waste flue gas from a heating boiler and / or catalytic cracking catalyst regeneration flue gas, and the components of the waste flue gas include SO2 and CO2.

[0038] According to the present invention, preferably, the mixing ratio of the heating boiler waste gas and the catalytic cracking catalyst regeneration flue gas, the concentration of SO2 in the waste flue gas, the concentration of CO2 in the waste flue gas and the temperature of the waste flue gas are each independently determined according to the water quality conditions of the residual waste water.

[0039] According to the present invention, preferably, the concentration of SO2 in the waste gas is 200-2000 mg / m 3 The concentration of CO2 in the waste flue gas is 8-15%. After being treated in steps S1 and S2, the waste flue gas adjusts the pH of the residual wastewater to 7.5-8.5.

[0040] According to the present invention, preferably, the reactions in steps S1 and S2 include desulfurization of the waste flue gas and / or a carbonization reaction using CO2 in the waste flue gas.

[0041] In the present invention, in steps S1 and S2, SO2 in the waste flue gas is absorbed by NaOH in the residual waste water, thereby realizing the synergistic desulfurization and purification treatment of the waste flue gas; at the same time, since NaOH absorbs SO2, the pH of the residual waste water is adjusted to within the range of 7.5-8.5, thereby synergistically realizing the conditioning of the residual waste water and improving the carbonization reaction efficiency; after the residual waste water is conditioned by the waste flue gas, the Na2CO3 in the residual waste water reacts with the CO2 in the waste flue gas to undergo a carbonization reaction, thereby utilizing the CO2 in the waste flue gas as a raw gas for carbonization, thereby reducing the system operating cost and improving the environmental protection benefit.

[0042] According to the present invention, preferably, the temperature of the waste flue gas is between 150-250°C; the waste flue gas is subjected to dust removal treatment before entering the heating and mixing unit;

[0043] The residual waste water and the waste flue gas are mixed in a cross-flow manner in the heating and mixing unit, and the temperature of the residual waste water reaches 35-50° C., preferably 40° C. in the heating and mixing unit.

[0044] In the present invention, in step S1, the residual waste water and the waste flue gas are mixed in the heating and mixing unit in a cross-flow manner, and the waste flue gas is broken into small bubbles under the action of hydraulic shear, and the bubble size ranges from 200μm to 100mm, thereby increasing the gas-liquid contact area, so that the residual waste water and the waste flue gas are fully in contact and react; at the same time, the breaking of the waste flue gas under the action of hydraulic shear also accelerates the gas-liquid heat transfer, and the waste heat of the waste flue gas is used to heat the residual waste water, thereby realizing the utilization of the waste heat of the waste flue gas and reducing the process energy consumption.

[0045] In the present invention, in step S2, the guide baffles on the inner pipe wall of the mixing main pipeline have a crushing function, and the waste flue gas is further sheared and crushed by the guide baffles, so that the bubble size of the waste flue gas dissolved in the residual waste water is further reduced, that is, the bubble size is reduced to 5μm-100μm, thereby increasing the gas-liquid contact area, and the residual waste water and the waste flue gas are further fully contacted and reacted; in addition, the liquid phase in the mixed absorption unit forms a liquid film on the surface of the guide baffle, thereby improving the gas-liquid contact, increasing the gas solubility capacity, strengthening the system's purification efficiency of SO2 in the waste flue gas and the carbonization efficiency of absorbing CO2, and enhancing the system's carbonization processing capacity.

[0046] In the present invention, the above-mentioned "the guide baffle has a crushing function, the waste gas is further sheared and crushed after passing through the guide baffle; the liquid phase in the mixed absorption unit forms a liquid film on the surface of the guide baffle" is achieved by the guide baffle structure of the present invention, as follows:

[0047] The guide baffle (the following description is from front to back according to the direction of the water flow) Figure 3-6 As shown:

[0048] A first groove is provided on one side of the guide baffle close to the inner wall of the mixing main pipe. As a preferred solution, the first groove is a semicircular groove. The first groove and the inner wall of the mixing main pipe form a first flow channel, and the first flow channel extends along the axial direction of the mixing main pipe. In the present invention, the first flow channel is referred to as liquid phase route No. ②.

[0049] A second flow channel is provided on one side of the guide baffle away from the inner wall of the mixing main pipe. In the present invention, the second flow channel is a semicircular groove that gradually expands from front to back. The second flow channel extends along the axial direction of the mixing main pipe. In the present invention, the second flow channel is referred to as the gas-liquid phase No. ① route;

[0050] As "the axes of the first sub-channel and the second sub-channel are straight lines; the axis of the third sub-channel is an arc convex toward the center of the mixing main channel, the axis of the fourth sub-channel is straight line, and the third sub-channel and the fourth sub-channel gradually approach the center of the mixing main channel along the flow direction of the fluid", it can be seen that the height of the guide baffle along the radial direction of the mixing main channel gradually increases from front to back. As a preferred embodiment, the distance from the top of one end of the third sub-channel away from the fourth sub-channel to the center of the mixing main channel is 0.5 times the radius of the mixing main channel (that is, the height of the front end of the guide baffle occupies 1 / 4 of the vertical height in the mixing main channel), and the distance from the top of one end of the fourth sub-channel away from the third sub-channel to the center of the mixing main channel is 1 / 6 of the radius of the mixing main channel (that is, the height of the rearmost end of the guide baffle occupies 1 / 3 of the vertical height in the mixing main channel).

[0051] and then:

[0052] Before entering the mixing and absorption unit, the gas and liquid are mixed in the heating and mixing unit, and then they will pass through the cyclone structure to change the parallel flow direction into the rotating flow direction. Due to the density difference between the gas and the liquid, during the cyclone process, the liquid gradually approaches the pipe wall, and the gas tends to converge toward the center of the pipe. During the cyclone process, the gas and liquid phases move by themselves due to the gravity difference, which enhances the gas-liquid contact efficiency and increases a certain amount of hydraulic shear force.

[0053] When the gas-liquid phase reaches the guide baffle, the guide baffle is distributed on the four walls of the mixing main pipeline. After the gas-liquid phase collides on the guide baffle, it enters routes ① and ②. Due to the rotating flow direction, the liquid phase is close to the pipe wall, so that route ② is composed entirely of liquid phase, and the gas phase is concentrated in the middle of the pipeline. The height of the guide baffle occupies 1 / 4 and 1 / 3 of the vertical height in the mixing main pipeline from low to high, respectively, so that path ① is covered with a small amount of liquid phase, and the top of the liquid phase is gas phase.

[0054] The guide baffles gradually become higher from front to back, and the widths of the No. ① and No. ② paths gradually increase (gradual expansion, such as Figure 4-5 As shown in the figure, the width of the groove of path ① increases more significantly, but the curvature of the groove gradually decreases (that is, the axis of the third sub-channel is an arc convex toward the center of the mixing main pipe, and the axis of the fourth sub-channel is a straight line). Therefore, the liquid phase on path ① spreads out in the gradually widening groove, thereby forming a gradually thinning liquid film and gradually raising the height of the guide baffle to contact the gas phase. The formation of the wastewater liquid film and the forced contact with the gas phase increase the hydraulic shear force of the wastewater on the gas phase, gradually improving the gas-liquid mass transfer efficiency and the wastewater treatment efficiency.

[0055] The wastewater in path ② moves at the bottom of the guide baffle. When it moves to the rear of the guide baffle, the direction of path ② is changed to a steep rise (i.e., a first angle is formed between the second sub-channel and the first sub-channel. In the present invention, the first angle can change the direction of path ② to a steep rise), and merges with the wastewater liquid film of path ①. And because there are more liquid phases in path ②, the 45-60° angle set at the outlet of path ① and the outlet of path ② realizes the forced turbulence of the wastewater in path ② on the wastewater liquid film of path ① after the conditioning treatment, providing the enhanced improvement of secondary hydraulic shear, and the mixed wastewater enters the next set of guide baffles.

[0056] Due to the large amount of wastewater in path ②, the wastewater at the outlet of path ① is in the form of a water film. At the junction of path ① and path ②, the liquid film in path ① is subjected to the strong impact force of the liquid phase in path ② and impacts the gas phase at an oblique upward angle. The instantaneous change in the flow direction of the liquid film strengthens the cutting and crushing ability of the liquid film on the gas phase, and promotes the formation of tiny bubbles wrapped in the liquid phase in the pipeline. Since the overall flow direction of the liquid phase is a rotating forward flow, the liquid phase containing tiny bubbles will quickly approach the wall. When entering the next guide baffle, the tiny bubbles in the wastewater liquid phase gather toward the center of the pipeline. By increasing the number of guide baffles, the spacing between the guide baffles can be shortened, so that except for the first group of guide baffles, the wastewater contacted by the subsequent guide baffles has many tiny bubbles near the center of the pipeline. When the wastewater carrying tiny bubbles away from the pipe wall touches the front end of the guide baffle, the wastewater containing no tiny bubbles or a small amount of tiny bubbles enters path ②, and the wastewater rich in tiny bubbles enters path ①. As the wastewater in path ① gradually expands to form a liquid film, tiny bubbles in the liquid phase gradually separate from the liquid phase. The tiny bubbles burst and cause local turbulence, which strengthens the gas-liquid contact and gas-liquid mass transfer, and improves the treatment and conditioning effect of the gas on the wastewater.

[0057] According to the present invention, preferably, the ratio of the inlet flow rate of the residual wastewater to the inlet flow rate of the waste flue gas is 1: (2-12.5) m 3 / m 3 According to the pH value of the residual wastewater, the Na2CO3 concentration of the residual wastewater, and the SO2 and CO2 concentrations in the waste gas, a reasonable distribution can be made to optimize the conditioning and carbonization reaction efficiency of the residual wastewater of the present invention. Preferably, the ratio of the inlet flow rate of the residual wastewater to the inlet flow rate of the waste gas is 1:6m 3 / m 3 .

[0058] According to the present invention, preferably, the rotation speed output of the rotating device is 200-2500rpm, which can be adjusted according to the total amount of waste gas and wastewater treated by the separation and recovery unit and the crystal size of the desired crystalline soda ash, thereby optimizing the separation effect of wastewater and crystalline soda ash in the system.

[0059] In the present invention, in step S3, the waste gas and wastewater system in the separation and recovery unit (i.e., the system in which the residual wastewater is mixed with the crushed waste flue gas and absorbs SO2 and CO2) is rapidly centrifuged under the stirring of the rotating device, which accelerates the movement of bubbles in the residual wastewater, ensures that the crystallized soda ash in the carbonization reaction will not crystallize in large pieces, and thus obtains uniformly crystallized sodium bicarbonate crystalline salt, which is convenient for the subsequent calcination, drying and recovery process, and ensures that the sodium carbonate product salt produced by the system of the present invention meets the requirements of GB / T210-2022I products, thereby improving the economy of the system; at the same time, a salt product recovery tank is provided at the bottom of the cylindrical side wall of the main body of the separation and recovery unit, and the crystallized soda ash obtained after the waste gas and wastewater system from the mixed absorption unit is swirled in the separation and recovery unit flows into the salt product recovery tank under the interception of the cylindrical side wall.

[0060] According to the present invention, preferably, the temperature of the purified waste gas is 110-160°C, and the concentration of SO2 in the purified waste gas is 20-50 mg / m 3 The method also includes sending the purified waste flue gas to the denitrification equipment in the factory area, achieving carbonization and coordinated purification of the waste flue gas in the factory area without generating and emitting waste gas, thereby improving the environmental benefits of the system of the present invention.

[0061] According to the present invention, preferably, the water quality conditions of the tempered waste liquid include: pH 7.5-8.5, temperature 35-45°C, Na2SO4 concentration 320-480g / L, and NaHCO3 mass concentration 80-105g / L; the method also includes recovering Na2SO4 in the tempered waste liquid.

[0062] According to the present invention, preferably, the crystalline soda ash is sodium bicarbonate crystalline salt, and the method further comprises recovering the sodium bicarbonate crystalline salt by centrifugation, calcination, and drying to obtain a sodium carbonate product salt, and the sodium carbonate product salt meets the requirements of GB / T 210-2022 Class I products.

[0063] According to the present invention, preferably,

[0064] The total alkali content of the sodium carbonate product salt is 99.5-99.8% based on dry Na2CO3;

[0065] The total alkali content of the sodium carbonate product salt is 98.2-99.1% based on wet basis Na2CO3;

[0066] The sodium carbonate product salt has a sodium chloride content of 0.04-0.15% based on dry NaCl;

[0067] SO4 on dry basis 2- The sulfate content of the sodium carbonate product salt is 0.01-0.03%;

[0068] Calculated on the basis of the sodium carbonate product salt, the content of 1.18 mm sieve residue of the sodium carbonate product salt is 0.25-0.9%.

[0069] The beneficial effects of the technical solution of the present invention are as follows:

[0070] (1) Compared with the prior art, the present invention completely uses hazardous waste alkali residue waste water and waste flue gas as raw materials, treats the waste in the factory area as resources, and realizes waste recycling. The overall equipment process of the present invention utilizes the waste heat of the waste flue gas and CO2 resources, and synergistically realizes the desulfurization of the waste flue gas, the conditioning of the residue waste water, and the recovery of sodium carbonate or sodium bicarbonate products. At the same time, there is no generation of waste water and waste gas, and it has the advantages of low operating costs and waste resource recovery, no additional waste gas and waste water are generated, and has excellent economic and environmental advantages.

[0071] (2) The present invention achieves that the residue after the incineration of alkali slag wastewater in the factory area is no longer discharged or outsourced for treatment, and cooperates with the waste flue gas to achieve flue gas desulfurization, treating waste with waste, and no additional waste is generated, which has good environmental and economic benefits.

[0072] (3) The system of the present invention has an optimized structure and can use the kinetic energy of the residual wastewater to break and cut the waste flue gas. The diversion structure strengthens the gas-liquid contact. The equipment has excellent SO2 treatment and CO2 absorption capabilities, is easy to operate and has strong adaptability to working conditions.

[0073] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0075] Figure 1 A cross-sectional schematic diagram of a system for resource utilization of waste flue gas and coordinated treatment of alkaline slag wastewater provided in Example 1 of the present invention is shown.

[0076] Figure 2 A schematic top view of a system for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater provided in Example 1 of the present invention is shown.

[0077] Figure 3 The flow channel structure diagram of the guide baffle of a system for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater provided by the present invention is shown.

[0078] Figure 4A top view of a guide baffle of a system for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater provided by the present invention is shown.

[0079] Figure 5 A schematic diagram of the water flow side of a guide baffle of a system for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater provided by the present invention is shown.

[0080] Figure 6 The fluid route diagram of the guide baffle of a system for resource utilization of waste flue gas and coordinated treatment of alkali slag wastewater provided by the present invention is shown.

[0081] The following are the descriptions of the reference numerals:

[0082] 1. Residue wastewater main pipeline; 2. Cyclone structure; 3. Waste flue gas introduction pipeline; 4. Heating and mixing unit; 5. Guide baffle; 6. Mixing absorption unit; 7. Separation and recovery unit; 8. Rotating device; 9. Exhaust pipe; 10. Salt product recovery tank; 11. Wastewater recovery pipe; 12. Inclined isolation plate.

[0083] 5.1, first flow channel; 5.2, second flow channel; 5.3, first sub-flow channel; 5.4, second sub-flow channel; 5.5, third sub-flow channel; 5.6, fourth sub-flow channel. DETAILED DESCRIPTION

[0084] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0085] Example 1

[0086] This embodiment provides a system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater, such as Figure 1 As shown, the system includes a heating and mixing unit 4, a mixing and absorption unit 6, and a separation and recovery unit 7;

[0087] There are four heating and mixing units 4, each of which includes a residual wastewater main pipeline 1 and four waste flue gas introduction pipelines 3; the four waste flue gas introduction pipelines 3 are vertically arranged on the side wall of the residual wastewater main pipeline 1; a swirl structure 2 is arranged at the outlet of the residual wastewater main pipeline;

[0088] There are four mixed absorption units 6, each of which includes a mixed main pipeline and six groups of guide baffles 5 (four guide baffles are evenly distributed on the pipe wall of each mixed absorption unit); the guide baffles 5 are arranged on the inner pipe wall of the mixed main pipeline, and the structure of the guide baffles is as follows: Figure 3-6 As shown, the second angle between the axis of the second sub-channel and the axis of the fourth sub-channel is 60°, the distance between the top of one end of the third sub-channel away from the fourth sub-channel and the center of the mixing main pipe is 0.5 times the radius of the mixing main pipe (that is, the height of the front end of the guide baffle occupies 1 / 4 of the vertical height in the mixing main pipe), and the distance between the top of one end of the fourth sub-channel away from the third sub-channel and the center of the mixing main pipe is 1 / 6 of the radius of the mixing main pipe (that is, the height of the rear end of the guide baffle occupies 1 / 3 of the vertical height in the mixing main pipe); the inlet of the mixing main pipe is connected to the outlet of the residual wastewater main pipe 1 through the swirl structure;

[0089] The separation and recovery unit 7 comprises a main body with a cylindrical side wall, and the outlet of the mixing main pipeline of each mixing absorption unit 6 is connected to the interior of the main body in the form of an external tangent line, such as Figure 2 As shown; a rotating device 8 and a wastewater recovery pipe 11 are provided at the bottom of the main body, and the rotating device 8 is used to make the waste gas and wastewater system entering the separation and recovery unit 7 swirl in the separation and recovery unit 7, and an inclined isolation plate 12 is also provided above the wastewater recovery pipe 11, and the inclined isolation plate 12 is used to prevent crystallized salt from clogging the wastewater recovery pipe 11, and the inclined angle of the inclined isolation plate 12 relative to the horizontal plane is 60°; a salt product recovery tank 10 is provided at the bottom of the side wall of the main body; an exhaust pipe 9 is provided at the top of the main body.

[0090] This embodiment also provides a method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater, wherein:

[0091] The alkaline residue wastewater is: the cracking furnace of the ethylene unit of a certain oil refinery produces cracking gas, so an alkaline washing tower is set up, sodium hydroxide is used as the alkaline solution, and the Lummus sequential separation process is used to remove the acidic gas in the cracking gas through alkaline washing and water washing, thereby obtaining the alkaline residue wastewater;

[0092] The waste gas is dust-removed, the temperature is 185°C, and the SO2 concentration is 410 mg / m 3 , the concentration of CO2 is 12%.

[0093] The method is carried out using the above-mentioned system and comprises the following steps:

[0094] S1: The above-mentioned alkali residue wastewater is incinerated to obtain residue, and the residue is dissolved in water to form residue wastewater mainly composed of Na2CO3, Na2SO4 and NaOH. The water quality of the residue wastewater is as follows: pH 8.8, Na2CO3 395g / L, Na2SO4 422g / L, the concentration of metal elements (Fe, Ca, Mg, Ni, Cu, Mn) is 0.003g / L, and the concentration of NaOH is 0.030g / L; the residue wastewater and the waste flue gas are mixed in the heating and mixing unit 4 in a cross-flow manner, the temperature of the residue wastewater is heated to 33°C in the heating and mixing unit, and the pH of the residue wastewater is reduced to 7.9. At the same time, the waste flue gas is broken into small bubbles under the action of hydraulic shear, and the bubble size ranges from 300μm to 20mm, and then enters the mixing absorption unit 6;

[0095] In this embodiment, the total inlet flow rate of the residual wastewater is 4m 3 / h, the liquid inlet flow rate of each heating and mixing unit is 1m 3 / h; the total intake flow of the waste gas is 22m 3 / h, the air intake flow rate of each heating and mixing unit is 5.5m 3 / h;

[0096] S2: In the mixed absorption unit 6, the guide baffle 5 is used to further strengthen the hydraulic shearing effect on the waste flue gas, and the waste flue gas is further broken into small bubbles under the action of the guide baffle, that is, the bubble size is reduced to 50μm-90μm, and the residual waste water forms a liquid film on the guide baffle, which accelerates the absorption of SO2 and CO2 in the waste flue gas, thereby further reducing the pH of the residual waste water to 7.6, and the temperature of the residual waste water rises to 41°C, and then enters the separation and recovery unit 7;

[0097] S3: In the separation and recovery unit 7, the rotating device 8 (600 rpm) is used to make the waste gas and wastewater system from the mixed absorption unit 6 swirl in the separation and recovery unit 7 to obtain crystallized soda ash, tempered waste liquid, and purified waste flue gas. The crystallized soda ash enters the salt product recovery tank 10, the tempered waste liquid flows into the wastewater recovery pipe 11, and the purified waste flue gas is discharged from the exhaust pipe 9.

[0098] The crystalline soda ash is a sodium bicarbonate crystalline salt. The method further comprises recovering the sodium bicarbonate crystalline salt by centrifugation, calcination and drying to obtain a sodium carbonate product salt, and:

[0099] The total alkali content of the sodium carbonate product salt is 99.7% based on dry Na2CO3;

[0100] The total alkali content of the sodium carbonate product salt is 98.9% based on wet basis Na2CO3;

[0101] The sodium chloride content of the sodium carbonate product salt is 0.05% based on dry NaCl;

[0102] SO4 on dry basis 2- The sulfate content of the sodium carbonate product salt is 0.03%;

[0103] Calculated on the basis of the sodium carbonate product salt, the content of 1.18 mm sieve residue of the sodium carbonate product salt is 0.3%. Therefore, the sodium carbonate product salt meets the requirements of GB / T 210-2022 Class I products.

[0104] The water quality conditions of the conditioned waste liquid include: pH 7.8, temperature 40°C, Na2SO4 concentration 436g / L, and NaHCO3 mass concentration 96g / L; the method also includes recovering Na2SO4 resources in the conditioned waste liquid;

[0105] The temperature of the purified waste gas is 142°C, and the concentration of SO2 in the purified waste gas is 32 mg / m 3 Therefore, it can be known that the waste flue gas in this embodiment has been desulfurized and purified; the method also includes sending the purified waste flue gas to the denitrification equipment in the factory.

[0106] Example 2

[0107] This embodiment provides a system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater. The difference between this embodiment and embodiment 1 is only that:

[0108] There are four heating and mixing units 4, each of which includes a residual wastewater main pipeline 1 and six waste flue gas introduction pipelines 3; the six waste flue gas introduction pipelines 3 are vertically arranged on the side wall of the residual wastewater main pipeline 1; two swirl structures 2 are arranged at the outlet of the residual wastewater main pipeline;

[0109] There are four mixed absorption units 6, each of which includes a mixed main pipeline and eight groups of guide baffles 5; the guide baffles 5 are arranged on the inner wall of the mixed main pipeline, and the structure of the guide baffles is as follows: Figure 3-6 As shown, the second angle between the axis of the second sub-channel and the axis of the fourth sub-channel is 45°; the inlet of the mixing main pipeline is connected to the outlet of the residual wastewater main pipeline 1;

[0110] The inclined isolation plate 12 has an inclination angle of 40° relative to the horizontal plane;

[0111] This embodiment also provides a method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater, wherein:

[0112] The alkaline residue wastewater is: the alkaline residue wastewater produced by alkaline washing of a certain oil refinery;

[0113] The waste flue gas is the flue gas from the regeneration of catalytic cracking catalyst and has been dust-removed. The temperature is 150°C and the concentration of SO2 is 620 mg / m 3 , the concentration of CO2 is 15%.

[0114] The method is carried out using the above-mentioned system and comprises the following steps:

[0115] S1: The above-mentioned alkali slag wastewater is incinerated to obtain a residue, and the residue is dissolved in water to form a residue wastewater, the water quality of which is as follows: pH 9.5, Na2CO3 416g / L, Na2SO4 368g / L, the concentration of metal elements (Fe, Ca, Mg, Ni, Cu, Mn) is 0.0028g / L, and the concentration of NaOH is 0.020g / L; the residue wastewater and the waste flue gas are mixed in the heating and mixing unit 4 in a cross-flow manner, the temperature of the residue wastewater is heated to 30°C in the heating and mixing unit, the pH of the residue wastewater is reduced to 8.4, and at the same time, the waste flue gas is broken into small bubbles under the action of hydraulic shear, and the bubble size ranges from 260μm to 50mm, and then enters the mixing absorption unit 6;

[0116] In this embodiment, the total inlet flow rate of the residual wastewater is 3.2m 3 / h, the liquid flow rate of each heating and mixing unit is 0.8m 3 / h; the total intake flow rate of the waste gas is 19.2m 3 / h, the air intake flow rate of each heating and mixing unit is 4.8m 3 / h;

[0117] S2: In the mixed absorption unit 6, the guide baffle 5 is used to further strengthen the hydraulic shearing effect on the waste flue gas. The waste flue gas is further broken into small bubbles under the action of the guide baffle 5, that is, the bubble size is reduced to 70μm-100μm, and the residual waste water forms a liquid film on the guide baffle, which accelerates the absorption of SO2 and CO2 in the waste flue gas, thereby further reducing the pH of the residual waste water to 7.9, and the temperature of the residual waste water rises to 38°C, and then enters the separation and recovery unit 7;

[0118] S3: In the separation and recovery unit 7, the rotating device 8 (300 rpm) is used to make the waste gas and wastewater system from the mixed absorption unit swirl in the separation and recovery unit to obtain crystallized soda ash, tempered waste liquid, and purified waste flue gas. The crystallized soda ash enters the salt product recovery tank 109, the tempered waste liquid flows into the wastewater recovery pipe 11, and the purified waste flue gas is discharged from the exhaust pipe 9.

[0119] The crystalline soda ash is a sodium bicarbonate crystalline salt. The method further comprises recovering the sodium bicarbonate crystalline salt by centrifugation, calcination and drying to obtain a sodium carbonate product salt, and:

[0120] The total alkali content of the sodium carbonate product salt is 99.6% based on dry Na2CO3;

[0121] The total alkali content of the sodium carbonate product salt is 98.5% based on wet basis Na2CO3;

[0122] The sodium carbonate product salt has a sodium chloride content of 0.12% based on dry NaCl;

[0123] SO4 on dry basis 2 -, the sulfate content of the sodium carbonate product salt is 0.02%;

[0124] Calculated on the basis of the sodium carbonate product salt, the content of 1.18 mm sieve residue of the sodium carbonate product salt is 0.85%. Therefore, the sodium carbonate product salt meets the requirements of GB / T 210-2022 Class I products.

[0125] The water quality conditions of the conditioned waste liquid include: pH 7.9, temperature 38°C, Na2SO4 concentration 376g / L, and NaHCO3 mass concentration 103g / L; the method also includes recovering Na2SO4 resources in the conditioned waste liquid;

[0126] The temperature of the purified waste gas is 128°C, and the concentration of SO2 in the purified waste gas is 48 mg / m 3 Therefore, it can be known that the waste flue gas in this embodiment has been desulfurized and purified; the method also includes sending the purified waste flue gas to the denitrification equipment in the factory.

[0127] Examples 3-10 and Comparative Example 1

[0128] To explore the effect of the number of guide baffles on the effluent quality of the mixed absorption unit 6 (step S2), Examples 3-10 and Comparative Example 1 were different in the number of guide baffles from Example 1, and other operations were the same as Example 1. The results are shown in Table 1.

[0129] Table 1

[0130] Number of guide baffles / group Outlet pH Outlet water temperature / ℃ Example 1 6 7.6 41 Example 3 8 7.5 42 Example 4 10 7.5 44 Example 5 12 7.4 45 Example 6 14 7.8 37 Example 7 16 8.0 34 Example 8 18 8.1 32 Example 9 4 7.6 40 Example 10 2 7.9 37 Comparative Example 1 0 8.1 31

[0131] From the comparison results in Table 1, it is found that setting a suitable number of guide baffles (4-12 groups) can enhance the contact efficiency between flue gas and wastewater, enhance mass transfer, promote the decrease of the pH value of the effluent from the mixed absorption unit, and increase the effluent temperature. Regulating the effluent pH of the mixed absorption unit to be close to neutral and increasing the effluent temperature to be close to 40-45°C is conducive to the subsequent carbonization process to separate sodium bicarbonate crystals. However, when the number of guide baffles exceeds 12 groups, due to the small interval between the guide baffles, it is difficult for the tiny bubbles in the wastewater to enter the No. ① path, and the overly dense guide baffles cause serious liquid phase disturbance, and the direction of the rotating flow in the pipeline is destroyed, resulting in the weakening of the guide baffle effect. When the number of guide baffles is less than 4 groups, due to the small number of guide baffles, the gas-liquid contact effect is low. When there are two groups of guide baffles, only the wastewater in the second group of guide baffles is rich in tiny bubbles, and the utilization rate of the tiny bubbles generated by hydraulic shear is low, so the effect is poor. When the guide baffle is not used, there is no enhancement of gas-liquid mass transfer, the pH of the effluent from the mixed absorption unit is as high as 8.1, the effluent temperature is as low as 31°C, the wastewater quality is poor, and the subsequent carbonization unit operation is affected. Through the above comparative analysis, it can be intuitively found that the guide baffle designed by the present invention has a significant effect of enhancing gas-liquid mass transfer and improving liquid conditioning and treatment.

[0132] Examples 11-22

[0133] The effect of the second angle between the axis of the second sub-channel and the axis of the fourth sub-channel on the effluent quality of the mixed absorption unit 6 (step S2) was investigated. Except for the second angle being different from that of Example 1, other operations of Examples 11-22 were the same as those of Example 1. The results are shown in Table 2.

[0134] Table 2

[0135] Angle / ° Outlet pH Outlet water temperature / ℃ Example 1 60 7.6 41 Embodiment 11 55 7.5 42 Example 12 50 7.6 41 Embodiment 13 45 7.5 41 Embodiment 14 40 7.8 38 Embodiment 15 35 7.9 36 Example 16 30 8.1 32 Embodiment 17 20 8.2 30 Embodiment 18 10 8.3 29 Embodiment 19 65 7.8 39 Embodiment 20 70 8.0 36 Embodiment 21 80 8.2 33 Embodiment 22 90 8.4 30

[0136] From the comparison results in Table 2, it can be found that the different angles between the outlet of path ① and the outlet of path ② in the guide baffle affect the pH and water temperature of the effluent of the mixed absorption unit. When the angle is within the range of 45-60°, the effluent quality is good, and the subsequent carbonization unit maintains efficient operation. When the angle is lower than 45°, the impact angle of the wastewater at the outlet of path ② on the liquid film at the outlet of path ① is small, and it is difficult to carry the liquid film to achieve efficient cutting and crushing of the gas phase, which reduces the generation rate of microbubbles and thus reduces the gas-liquid mass transfer. When the angle is higher than 60°, the outlet of path ② tends to turn back in the direction of the incoming water. The larger the angle, the stronger the wastewater return effect. The wastewater at the outlet of path ② conflicts with the swirling forward wastewater in the pipeline, affecting the rotational flow of the gas-liquid phase. After the rotational flow is destroyed, it is difficult for the gas to gather in the center of the pipeline, and the overall gas-liquid contact in the pipeline and the effect of the guide baffle on the hydraulic shear force are weakened, resulting in the deterioration of the effluent quality of the mixed absorption unit.

[0137] Examples 23-29

[0138] The influence of "the distance from the top of one end of the third sub-channel away from the fourth sub-channel to the center of the mixing main pipeline (the height of the front end of the guide baffle occupies the vertical height in the mixing main pipeline), the distance from the top of one end of the fourth sub-channel away from the third sub-channel to the center of the mixing main pipeline (the height of the rear end of the guide baffle occupies the vertical height in the mixing main pipeline)" on the effluent quality of the mixing absorption unit 6 (step S2) was explored. Except for the height ratio being different from that of Example 1, other operations of Examples 23-29 were the same as those of Example 1. The results are shown in Table 3.

[0139] Table 3

[0140]

[0141] From the comparison results in Table 3, it can be found that regulating the front and rear end heights of the guide baffle will affect the pH and water temperature of the outlet water of the mixed absorption unit. In general, keeping the front end of the guide baffle lower and raising the rear end of the guide baffle is beneficial to strengthening the gas-liquid mixing. When the front end of the guide baffle is higher than the rear end height of the guide baffle or the heights of the two are the same, the effect of path ① fails and the wastewater liquid film cannot be produced, resulting in a significant reduction in the effect of the guide baffle and deterioration of the outlet water pH and water temperature. When the front end height of the guide baffle is too low, the increase in the water inlet of path ① will cause the wastewater liquid film thickness to increase, the gas-liquid mass transfer to deteriorate, and thus the outlet water quality to deteriorate. Through experimental comparison, when the front end height of the guide baffle designed by the present invention accounts for 1 / 4 of the pipeline height and the rear end height accounts for 1 / 3-1 / 2 of the pipeline height, the guide baffle has a significant effect, improves the gas-liquid mass transfer effect, and improves the outlet water quality of the mixed absorption unit.

[0142] Examples 30-33 and Comparative Example 2

[0143] To explore the effect of the number of cyclone structures on the effluent quality of the mixed absorption unit 6 (step S2), Examples 30-33 and Comparative Example 2 were the same as Example 1 except that the number of cyclone structures was different. The results are shown in Table 4.

[0144] Table 4

[0145] Number of swirl structures Outlet pH Outlet water temperature / ℃ Example 1 1 7.6 41 Embodiment 30 2 7.6 42 Embodiment 31 3 7.7 41 Embodiment 32 4 7.8 37 Embodiment 33 5 7.9 35 Comparative Example 2 0 8.2 32

[0146] From the comparison results in Table 4, it can be found that when a cyclone structure is provided, by realizing the rotating forward motion of the wastewater and the waste flue gas, it is beneficial to the enhanced mass transfer and exchange of the wastewater and the waste flue gas at the guide baffle. However, when there is no cyclone structure, the wastewater and the waste flue gas in the pipeline are transported in a direct forward manner, which significantly reduces the enhanced mass transfer effect of the guide baffle, causing the water quality of the effluent from the mixed absorption unit to deteriorate significantly. When the number of cyclone structures is too large (more than 3), too many cyclone structures will occupy more pipeline area, reduce the distance between the guide baffles, reduce the effect of the guide baffles, and cause the water quality of the effluent from the mixed absorption unit to deteriorate. By comparison, it can be found that in the device of the present invention, it is relatively reasonable to set 1 to 3 cyclone structures, which can improve the gas-liquid mass transfer effect and improve the effluent quality of the mixed absorption unit.

[0147] Examples 34-42

[0148] The effect of the inclination angle of the inclined isolation plate relative to the horizontal plane on the recovery rate of Na2CO3 was investigated. Except for the different inclination angles, the other operations of Examples 34-42 were the same as those of Example 1. The results are shown in Table 5.

[0149] Table 5

[0150] Isolation board angle / ° <![CDATA[Sodium carbonate recovery rate / %]]> Example 1 60 84.7 Embodiment 34 70 84.8 Embodiment 35 75 84.9 Embodiment 36 50 84.3 Embodiment 37 40 84.1 Embodiment 38 30 84.0 Embodiment 39 20 78.6 Embodiment 40 10 75.2 Embodiment 41 80 76.3 Embodiment 42 90 73.2

[0151] It is found from the comparison results in Table 5 that regulating the angle of the partition plate can affect the recovery rate of Na2CO3 in the treated wastewater. When the angle of the partition plate is within the range of 30-75°, the recovery rate of Na2CO3 in the wastewater is higher than 80%. When the angle of the partition plate is low (less than 30°), the partition plate is too close to the residual wastewater recovery pipe, and the wastewater in the separation and recovery unit will cause a large disturbance when it is discharged through the residual wastewater recovery pipe, so that the NaHCO3 crystals are attracted to the residual wastewater recovery pipe by the disturbance and are not recovered by the product recovery tank. When the angle of the partition plate is high (greater than 75°), the protection and covering effect of the partition plate on the residual wastewater recovery pipe is small, and the NaHCO3 crystals are directly discharged from the residual wastewater recovery pipe together with the wastewater, thereby causing the Na2CO3 recovery rate to decrease.

[0152] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater, characterized in that: The system comprises a heating and mixing unit, a mixing and absorbing unit and a separation and recovery unit; The heating and mixing unit comprises a residual wastewater main pipeline and a waste flue gas introduction pipeline; the waste flue gas introduction pipeline is vertically arranged on the side wall of the residual wastewater main pipeline; a swirl structure is arranged at the outlet of the residual wastewater main pipeline; The mixing absorption unit comprises a mixing main pipeline and a guide baffle; the guide baffle is arranged on the inner wall of the mixing main pipeline; the inlet of the mixing main pipeline is connected with the outlet of the residual wastewater main pipeline through the cyclone structure; The separation and recovery unit includes a main body with a cylindrical side wall, and the outlet of the mixing main pipeline is connected to the interior of the main body in the form of an external tangent line; a rotating device and a wastewater recovery pipe are provided at the bottom of the main body, and the rotating device is used to make the waste gas and wastewater system entering the separation and recovery unit swirl in the separation and recovery unit; a salt product recovery tank is provided at the bottom of the side wall of the main body; and an exhaust pipe is provided at the top of the main body.

2. The system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 1, wherein: The heating and mixing units and the mixing and absorbing units are multiple and the number is the same, and the outlet of the mixing main pipeline of each mixing and absorbing unit is connected to the inside of the main body in the form of an external tangent line; In each mixed absorption unit, the structure of the guide baffle is: A first groove is provided on one side of the guide baffle plate close to the inner wall of the main mixing pipe, the first groove and the inner wall of the main mixing pipe enclose a first flow channel, the first flow channel extends along the axial direction of the main mixing pipe, and a second flow channel is provided on one side of the guide baffle plate away from the inner wall of the main mixing pipe, the second flow channel extends along the axial direction of the main mixing pipe; The first flow channel is gradually expanded and includes a first sub-flow channel and a second sub-flow channel sequentially arranged along the flow direction of the fluid, the axes of the first sub-flow channel and the second sub-flow channel are straight lines, and a first angle is formed between the second sub-flow channel and the first sub-flow channel; The second flow channel is gradually expanded and includes a third sub-flow channel and a fourth sub-flow channel sequentially arranged along the flow direction of the fluid, the axis of the third sub-flow channel is an arc convex toward the center of the main mixing channel, the axis of the fourth sub-flow channel is a straight line, and the third sub-flow channel and the fourth sub-flow channel gradually approach the center of the main mixing channel along the flow direction of the fluid; One end of the second sub-channel away from the first sub-channel is connected to one end of the fourth sub-channel away from the third sub-channel, and a second angle between the axis of the second sub-channel and the axis of the fourth sub-channel is 43°-62°.

3. The system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 2, wherein: The number of the mixed absorption units is 2-10; In each mixed absorption unit, the number of the guide baffles is 4-14 groups, and each group has 2-6 guide baffles evenly distributed on the inner wall of the mixed main pipeline; The distance between the top of one end of the third sub-channel away from the fourth sub-channel and the center of the mixing main pipe is 0.45-0.55 times the radius of the mixing main pipe; The distance between the top of one end of the fourth sub-channel away from the third sub-channel and the center of the mixing main pipe is 0-0.15-0.17 times the radius of the mixing main pipe.

4. The system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 1, wherein: An inclined isolation plate is also provided above the wastewater recovery pipe, and the inclined isolation plate is used to prevent crystallized salt from clogging the wastewater recovery pipe; Preferably, the inclined isolation plate has an inclination angle of 25-78° relative to the horizontal plane.

5. The system for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 1, wherein: In each heating and mixing unit, the number of the swirl structures is 1-4; preferably, when there are multiple swirl structures, the multiple swirl structures are sequentially arranged at the outlet of the residual wastewater main pipeline along the flow direction of the fluid; With respect to each residual wastewater main pipeline, the waste flue gas introduction pipeline is one or more; Preferably, the number of the waste flue gas introduction pipes is 1-8; Preferably, when there are multiple waste flue gas introduction pipes, the multiple waste flue gas introduction pipes are vertically arranged in a ring on the side wall of the residual wastewater main pipe.

6. A method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater, characterized in that: The method adopts the system described in any one of claims 1 to 5, comprising the following steps: S1: the residual waste water and the waste flue gas are mixed in the heating and mixing unit in a cross-flow manner, the waste flue gas is broken under the action of hydraulic shear, the residual waste water and the waste flue gas are fully contacted and reacted, and then enter the mixing absorption unit; S2: In the mixed absorption unit, the guide baffle is used to further strengthen the hydraulic shearing effect on the waste flue gas, and the residual waste water and the waste flue gas are further fully contacted and reacted, and then enter the separation and recovery unit; S3: In the separation and recovery unit, the rotating device is used to cause the waste gas and wastewater system from the mixed absorption unit to swirl in the separation and recovery unit to obtain crystallized soda ash, tempered waste liquid, and purified waste flue gas. The crystallized soda ash enters the salt product recovery tank, the tempered waste liquid flows into the wastewater recovery pipe, and the purified waste flue gas is discharged from the exhaust pipe.

7. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 6, wherein: The residue wastewater is obtained by incinerating the alkali residue wastewater produced by the alkali washing device and then dissolving the residue in water to obtain the wastewater.

8. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 7, wherein: The alkali washing device is at least one of a device for washing acidic gases in cracking gas during catalytic cracking, an alkali liquid washing device for wet desulfurization in a coking process, an alkali liquid washing device for desulfurization and deacidification of flue gas from waste incineration power generation, and an alkali liquid washing device for deacidification of flue gas from a hazardous waste incinerator.

9. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 7, wherein: The water quality conditions of the residual wastewater include: pH 8-12, Na2SO4 concentration 300-470g / L, Na2CO3 concentration 320-460g / L, metal element concentration 0.001-0.010g / L, NaOH concentration 0-0.030g / L.

10. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 6, wherein: The waste flue gas is waste flue gas from a heating boiler and / or regeneration flue gas from a catalytic cracking catalyst, and the components of the waste flue gas include SO2 and CO2.

11. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 10, wherein: The mixing ratio of the heating boiler exhaust gas and the catalytic cracking catalyst regeneration exhaust gas, the SO2 concentration in the exhaust gas, the CO2 concentration in the exhaust gas and the temperature of the exhaust gas are independently determined according to the water quality conditions of the residual wastewater.

12. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 11, wherein: The concentration of SO2 in the waste gas is 200-2000 mg / m 3 The concentration of CO2 in the waste flue gas is 8-15%. After being treated in steps S1 and S2, the waste flue gas adjusts the pH of the residual wastewater to 7.5-8.

5.

13. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 12, wherein: The reactions in steps S1 and S2 include desulfurization of the waste flue gas and / or carbonization reaction using CO2 in the waste flue gas.

14. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 11, wherein: The temperature of the waste flue gas is between 150-250°C; the waste flue gas is dust-removed before entering the heating and mixing unit; The residual waste water and the waste flue gas are mixed in a cross-flow manner in the heating and mixing unit, and the temperature of the residual waste water reaches 35-50° C. in the heating and mixing unit.

15. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 6, wherein: The ratio of the inlet flow rate of the residual wastewater to the inlet flow rate of the waste flue gas is 1: (2-12.5) m 3 / m 3 .

16. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 6, wherein: The rotation speed output of the rotating device is 200-2500rpm; The temperature of the purified waste gas is 110-160°C, and the concentration of SO2 in the purified waste gas is 20-50 mg / m 3 ; The method also includes sending the purified waste flue gas to a denitration device in a plant area; The water quality conditions of the conditioned waste liquid include: pH 7.5-8.5, temperature 35-45°C, Na2SO4 concentration 320-480g / L, and NaHCO3 mass concentration 80-105g / L; the method also includes recovering Na2SO4 in the conditioned waste liquid; The crystalline soda ash is a crystalline sodium bicarbonate salt. The method also includes recovering the crystalline sodium bicarbonate salt by centrifugation, calcination, and drying to obtain a sodium carbonate product salt. The sodium carbonate product salt meets the requirements of GB / T210-2022 Class I products.

17. The method for resource utilization of waste flue gas and coordinated treatment of alkali residue wastewater according to claim 16, wherein: The total alkali content of the sodium carbonate product salt is 99.5-99.8% based on dry Na2CO3; The total alkali content of the sodium carbonate product salt is 98.2-99.1% based on wet basis Na2CO3; The sodium carbonate product salt has a sodium chloride content of 0.04-0.15% based on dry NaCl; SO4 on dry basis 2- The sulfate content of the sodium carbonate product salt is 0.01-0.03%; Calculated on the basis of the sodium carbonate product salt, the content of 1.18 mm sieve residue of the sodium carbonate product salt is 0.25-0.9%.

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