An exhaust gas absorption and recycling device and process for synthesizing DETX

Abstract

The present invention relates to a tail gas absorption and recycling device and process for synthesizing DETX. In view of the differences in the components of the tail gas in the initial stage, rapid reaction stage and reaction termination stage of the DETX synthesis reaction, a first tail gas absorption tower and a second tail gas absorption tower are provided. The first tail gas absorption tower is used to absorb the tail gas in the rapid reaction stage to ensure that the main component of the absorption liquid is sodium bisulfite, and the second tail gas absorption tower is used to absorb the tail gas in the initial stage and the termination stage of the reaction. In the tail gas absorption and recycling device of the present invention, an absorption liquid rich in sodium bisulfite is obtained through a staged absorption method, which is used as an oxidative destructor in the TPO synthesis process, turning waste into treasure, realizing the resource utilization of high-salt wastewater, saving the treatment cost of high-salt wastewater in the DETX synthesis process, and at the same time reducing the procurement cost of sodium bisulfite in the TPO synthesis process, having good economic and environmental benefits.

Description

Technical Field

[0001] The present invention belongs to the field of photoinitiator preparation, and relates to a device and process for recycling the tail gas absorption in the synthesis of DETX. Background Art

[0002] 2,4 - Diethylthioxanthone (DETX) is an efficient free radical type II photoinitiator. It has a relatively long ultraviolet absorption wavelength, which can avoid the influence of pigments on ultraviolet light absorption, and is widely used in fields such as UV wood coatings, offset printing inks, photoresists, adhesives, and automotive metal coatings.

[0003] CN108069935A discloses a preparation method of 2,4 - diethylthioxanthone, including: adding 2,4 - diethylbenzenethiol and a base into a solvent, completely converting 2,4 - diethylbenzenethiol into 2,4 - diethylbenzenethiolate under heating conditions, then adding o - chlorobenzonitrile, raising the temperature to 110 - 160 °C, holding the reaction, monitoring the reaction by TLC or gas phase, after the reaction ends, distilling off the solvent under reduced pressure to obtain the crude product of 2 - (2,4 - diethylbenzenethiolyl)benzonitrile; then dissolving the above - mentioned crude product in toluene, cooling to below 5 °C in an ice bath, slowly dropping 95% - 98% concentrated sulfuric acid, heating to 80 - 110 °C, holding the reaction, monitoring the reaction by TLC or gas phase, after the reaction ends, cooling to room temperature, adding water to the reaction system, stirring for 0.5 - 1.0 hour, standing, separating the aqueous phase, washing the organic phase with water until neutral, stripping under reduced pressure, and recrystallizing with anhydrous methanol to obtain a light yellow solid, namely 2,4 - diethylthioxanthone; CN110845471A discloses that using thiosalicylic acid or dithiosalicylic acid, 1,3 - diethylbenzene as raw materials, concentrated sulfuric acid as a catalyst and solvent, under the action of a co - catalyst, carrying out a condensation reaction at a temperature of 0 - 70 °C for 4 - 8 hours. Concentrating, extracting, concentrating, recrystallizing and other post - treatment processes are completed in the same reaction device, and the obtained product is then filtered and dried to finally obtain high - purity 2,4 - diethylthioxanthone; in the above - mentioned preparation methods of 2,4 - diethylthioxanthone, the raw materials all contain concentrated sulfuric acid. The treatment of its synthesis waste gas generally adopts direct injection into an alkali solution absorption device for treatment. After acid - base neutralization, the waste liquid is concentrated to make salt, and the waste salt is disposed of as hazardous waste, with extremely high treatment difficulty and high treatment cost.

[0004] Therefore, it is still of great significance to develop a device and method for resource utilization of waste gas in the DETX synthesis reaction. Summary of the Invention

[0005] The object of the present invention is to provide a tail gas absorption and recycling device and process for synthesizing DETX. In view of the differences in the components of the tail gas in the initial reaction stage, rapid reaction stage, and reaction termination stage of the DETX synthesis reaction, a first tail gas absorption tower and a second tail gas absorption tower are provided. The first tail gas absorption tower is used to absorb the tail gas in the rapid reaction stage to ensure that the main component of the absorption liquid is sodium bisulfite, and the second tail gas absorption tower is used to absorb the tail gas in the initial reaction stage and the reaction termination stage; in the present invention, the tail gas absorption and recycling device obtains an absorption liquid rich in sodium bisulfite through a staged absorption method, and uses it as an oxidation destroyer in the TPO synthesis process, turning waste into treasure, realizing the resource utilization of high-salt wastewater, saving the treatment cost of high-salt wastewater in the DETX synthesis process, and at the same time reducing the procurement cost of sodium bisulfite in the synthesis process of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), having good economic and environmental benefits.

[0006] In the present invention, in the DETX synthesis reaction, the criteria for delimiting the initial reaction stage, rapid reaction stage, and reaction termination stage are as follows;

[0007] During the DETX synthesis reaction process, with the progress of the reaction, a large amount of foam will be generated in the kettle. During the process from the initial reaction stage to the rapid reaction stage, the foam height will increase and the occupied volume will increase. When it reaches the maximum value, the subsequent reaction rate will decrease, the foam height will decrease, and the foam height will continuously decrease until the reaction termination stage; in the present invention, the "rapid reaction stage" is defined as the lower limit value of the ratio of the foam volume to the volume of the DETX synthesis reaction kettle in the DETX synthesis reaction kettle is above 5%. For example, when the lower limit value of the ratio of the foam volume to the volume of the DETX synthesis reaction kettle in the rapid reaction stage is 15%, that is, when the ratio of the foam volume to the volume of the DETX synthesis reaction kettle ≥ 15%, it is considered that the reaction in the DETX synthesis reaction kettle is in the rapid reaction stage. Preferably, the "rapid reaction stage" refers to the lower limit value of the ratio of the foam volume to the volume of the DETX synthesis reaction kettle in the DETX synthesis reaction kettle is 10% - 20%.

[0008] The initial reaction stage in the present invention includes the feeding stage in the DETX synthesis reaction kettle, and at this time, the gas outlet of the DETX synthesis reaction kettle is connected to the second tail gas absorption tower.

[0009] To achieve the object of the present invention, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a tail gas absorption and recycling device for synthesizing DETX, including a first tail gas absorption tower and a second tail gas absorption tower;

[0011] The first tail gas absorption tower is used for absorbing the tail gas in the rapid reaction stage of the DETX synthesis reaction kettle;

[0012] The second tail gas absorption tower is used for absorbing the tail gas in the start-up stage and the reaction termination stage of the DETX synthesis reactor.

[0013] In the current DETX production process, waste gas is generated during the synthesis reaction. Generally, the waste gas is directly introduced into an alkali liquor absorption tower for treatment. After acid-base neutralization, the waste liquid is concentrated to produce salt, and the waste salt is disposed of as hazardous waste. This process has problems such as high treatment difficulty and high treatment cost. To solve the above technical problems, through the analysis of the tail gas components, it is found that during the DETX synthesis reaction, the main component of the tail gas is sulfur dioxide, and the components in the absorption liquid include sodium bisulfite, sodium bisulfate, and sodium sulfite, with the main component being sodium bisulfate. Through the analysis of the waste gas composition and absorption liquid composition during the entire reaction process, it is found that the reason for the main component of the absorption liquid being sodium bisulfate is as follows: In the DETX synthesis reactor, at the start of the reaction in the start-up stage, sulfur dioxide is generated. As the reaction progresses, the generated sulfur dioxide increases, expelling the air in the reactor and pipeline and entering the tail gas absorption tower. In addition, in the reaction termination stage, as the amount of SO2 generated decreases, to maintain the pressure balance in the DETX synthesis reactor, air is replenished into the reactor, resulting in an oxygen-rich atmosphere entering the absorption tower, thereby oxidizing the reducing sodium bisulfite generated by the reaction of SO2 with liquid alkali to form sodium bisulfate. Especially when dealing with DETX synthesis reactors involving multiple asynchronous operations, due to the influence of negative pressure feeding, a large amount of air will enter the absorption tower. Based on the above research findings, the solution of the present invention sets up the first tail gas absorption tower and the second tail gas absorption tower, and absorbs the waste gas generated during the DETX synthesis stage in stages, thereby ensuring that the main component of the absorption liquid in the first tail gas absorption tower is sodium bisulfite, and using it as an oxidation destroyer in the TPO synthesis section, thereby realizing the resource utilization of the tail gas absorption liquid, reducing the generation and treatment cost of high-salt wastewater, and at the same time reducing the procurement cost of sodium bisulfite, thus greatly reducing the production cost and enhancing the product competitiveness of the enterprise.

[0014] The chemical equation of the DETX synthesis reaction in the present invention is as follows;

[0015]

[0016] Its synthesis process mainly includes: synthesis. Add m - diethylbenzene into the DETX synthesis reactor, add dithiosalicylic acid under stirring conditions, close the solid feeding port, add concentrated sulfuric acid with a concentration of 97wt% - 98.5wt% under stirring conditions, slowly heat the reactor to 90 - 98°C, and keep the temperature for reaction for 4 - 8h. SO2 is generated during the reaction process and is absorbed by the tail gas absorption device. After detecting that there is no reactant in the liquid phase of the reactants, discharge the material. Extraction: Transfer the synthetic material to the extraction kettle, add non - polar organic solvent and water, extract the product in the reaction solution, stir, stand still, separate the liquid, collect the lower acid liquid phase and the upper organic phase and transfer them to the water - washing kettle, and then obtain the DETX product through water - washing, neutralization, solvent removal, crystallization, centrifugation, and drying.

[0017] The tail gas absorption device described in the present invention is mainly used for absorbing the tail gas in the synthesis section of the DETX synthesis process.

[0018] Preferably, the gas inlet of the first tail gas absorption tower is connected to the gas outlet of the DETX synthesis reactor, and a valve is provided at the gas inlet of the first tail gas absorption tower.

[0019] Preferably, the gas inlet of the second tail gas absorption tower is connected to the gas outlet of the DETX synthesis reactor, and a valve is provided at the gas inlet of the second tail gas absorption tower.

[0020] Preferably, the gas inlet of the first tail gas absorption tower, the gas inlet of the second tail gas absorption tower and the gas outlet of the DETX synthesis reactor are connected through a multi - way valve.

[0021] Here, the multi - way valve includes a three - way valve.

[0022] By setting valves at the gas inlets of the first tail gas absorption tower and the second tail gas absorption tower, the present invention controls the tail gas generated in different reaction stages in the DETX synthesis reactor to enter different absorption towers respectively, thereby facilitating the control of the tail gas absorption process.

[0023] Preferably, the gas outlet of the first tail gas absorption tower is connected to the gas inlet of the second tail gas absorption tower.

[0024] In the present invention, the first tail gas absorption tower is used to absorb the tail gas in the rapid reaction stage of the DETX synthesis reaction. The concentration of SO2 in its tail gas is high. To avoid air pollution caused by incompletely absorbed SO2, the tail gas of the first tail gas absorption tower is injected into the second tail gas absorption tower to achieve more complete absorption of SO2.

[0025] Preferably, a blower is provided between the gas inlet of the first tail gas absorption tower and the gas outlet of the DETX synthesis reactor.

[0026] Preferably, a blower is provided between the gas inlet of the second tail gas absorption tower and the gas outlet of the DETX synthesis reactor.

[0027] Here, a blower is provided at the gas inlet of the first tail gas absorption tower and the gas inlet of the second tail gas absorption tower, which is convenient for transporting gas into the absorption tower to complete the tail gas absorption process.

[0028] Preferably, the number of the DETX synthesis reactors is multiple, preferably ≥3, such as 4 or 5, etc.

[0029] Preferably, different DETX synthesis reactors are independently connected to the first tail gas absorption tower and the second tail gas absorption tower respectively.

[0030] In the present invention, only when the reaction in the DETX synthesis reactor is in the rapid reaction stage, its gas outlet is connected to the first tail gas absorption tower; in other cases, its gas outlet is connected to the second tail gas absorption tower. Multiple DETX synthesis reactors are connected to the same set of tail gas treatment devices, that is, they are all connected to the same first tail gas absorption tower and the same second tail gas absorption tower. Since the DETX synthesis reactor generally adopts the negative pressure asynchronous feeding method, when using a traditional single tail gas absorption tower, during the asynchronous feeding process, especially during the solid-phase feeding process, a large amount of air will be introduced into the tail gas absorption tower, causing the reduction substances in the tail gas absorption tower to be oxidized; while in the device of the present invention, during the asynchronous solid-phase feeding process, the gas outlet of the feeding kettle is connected to the second tail gas absorption tower, and the gas outlet of the reactor in the rapid reaction stage is connected to the first tail gas absorption tower, effectively avoiding the oxidation of the reduction substances in the first tail gas absorption tower. Furthermore, the absorption liquid in the first tail gas absorption tower can be used as the oxidation destroyer in the TPO oxidation section, realizing the resource utilization of high-salt wastewater.

[0031] Preferably, the tail gas absorption and recycling device further includes a control module, and the control module is used to control the opening and closing states of the valves at the gas inlet of the first tail gas absorption tower and the gas inlet of the second tail gas absorption tower.

[0032] Here, a control module is provided. When the reaction in the DETX synthesis reactor is in the reaction start stage, control to close the gas inlet valve of the first tail gas absorption tower and open the gas inlet valve of the second tail gas absorption tower to absorb the tail gas with a relatively high oxygen concentration; then when the reaction in the DETX synthesis reactor enters the rapid reaction stage, control to close the gas inlet valve of the second tail gas absorption tower and open the gas inlet valve of the first tail gas absorption tower to absorb the high-concentration SO2; further, when the reaction in the DETX synthesis reactor enters the reaction termination stage, control to close the gas inlet valve of the first tail gas absorption tower and open the gas inlet valve of the second tail gas absorption tower to absorb the tail gas with a relatively high oxygen concentration; thus facilitating the control of the tail gas absorption process.

[0033] Preferably, the tail gas absorption and recycling device further includes a monitoring module for monitoring the height of the foam in the DETX synthesis reactor.

[0034] By providing the monitoring module, the present invention monitors the progress of the reaction in the DETX synthesis reactor, and then controls the opening and closing states of the valves at the gas inlets of the first tail gas absorption tower and the second tail gas absorption tower through the control module, improving the controllability of the operation process.

[0035] Preferably, both the first tail gas absorption tower and the second tail gas absorption tower are selected from spray towers.

[0036] Preferably, the spraying liquid of the spray tower is selected from an alkali solution with a concentration of 15 wt% to 30 wt%, such as 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt%, 26 wt% or 28 wt%, etc.

[0037] Preferably, the alkali solution is selected from an aqueous sodium hydroxide solution.

[0038] Preferably, the tail gas absorption and recycling device further includes a TPO synthesis reaction liquid post-treatment kettle, and the liquid outlet of the first tail gas absorption tower is connected to the absorption liquid inlet of the TPO synthesis reaction liquid post-treatment kettle.

[0039] Preferably, the tail gas absorption and recycling device further includes a drip tank. The liquid inlet of the drip tank is connected to the liquid outlet of the first tail gas absorption tower, and the liquid outlet of the drip tank is connected to the absorption liquid inlet of the TPO synthesis reaction liquid post-treatment kettle.

[0040] A drip tank is provided between the first tail gas absorption tower and the TPO synthesis reaction liquid post-treatment kettle. The drip tank is used to store the absorption liquid of the first tail gas absorption tower, and the setting of the drip tank facilitates the control of the addition rate of the absorption liquid, thereby buffering the entire operation process and facilitating the stable progress of the process.

[0041] Preferably, the tail gas absorption and recycling device further includes a waste water storage tank, and the bottom waste water outlet of the TPO synthesis reaction liquid post-treatment kettle is connected to the waste water storage tank.

[0042] The waste water storage tank is provided here to store the waste water obtained by liquid separation. After collecting a certain amount, it is transferred to a sewage treatment station for treatment.

[0043] Preferably, an alkali solution inlet is provided on the TPO synthesis reaction liquid post-treatment kettle.

[0044] Preferably, the tail gas absorption and recycling device further includes an alkali solution drip tank, and the liquid outlet of the alkali solution drip tank is connected to the alkali solution inlet of the TPO synthesis reaction liquid post-treatment kettle.

[0045] An alkali solution dropping tank is provided here to facilitate controlling the addition rate of the alkali solution during the alkali washing process.

[0046] Preferably, the tail gas absorption and recycling device further includes an alkali washing solution storage tank, and the bottom alkali washing solution outlet of the TPO synthesis reaction solution post-treatment kettle is connected to the alkali washing solution storage tank.

[0047] The alkali washing solution storage tank here is used to store the separated alkali washing solution.

[0048] Preferably, an organic phase discharge port is provided at the bottom of the TPO synthesis reaction solution post-treatment kettle.

[0049] The organic phase discharge port here is used to output the organic phase containing TPO obtained after alkali washing and liquid separation.

[0050] Preferably, the outside of the TPO synthesis reaction solution post-treatment kettle is wrapped with a cooling jacket.

[0051] In the present invention, during the reaction of adding the absorption liquid of the first tail gas absorption tower to the TPO synthesis reaction solution and during the alkali washing process, heat is released during the reaction. A cooling jacket is provided here to facilitate process temperature control, ensure the smooth termination of the TPO oxidation reaction, and ensure the alkali washing effect.

[0052] Preferably, a stirring paddle is provided inside the TPO synthesis reaction solution post-treatment kettle.

[0053] Preferably, the reaction solution inlet of the TPO synthesis reaction solution post-treatment kettle is connected to the reaction solution outlet of the TPO oxidation reaction kettle.

[0054] The TPO oxidation reaction kettle here is used for the oxidation reaction during the TPO synthesis process. After the oxidation reaction is completed, an oxidation destroying agent needs to be added to terminate the reaction, and then the product is separated, thereby reducing the safety hazards of post-treatment and facilitating the storage of wastewater; when the reaction in the TPO oxidation reaction kettle proceeds to a certain extent, the reaction solution is transferred to the TPO synthesis reaction solution post-treatment kettle of the present invention, and then an oxidation destroying agent is added to terminate the reaction and perform alkali washing to separate the product TPO.

[0055] In a second aspect, the present invention provides a tail gas absorption and recycling process for synthesizing DETX. The process uses the tail gas absorption and recycling device as described in the first aspect, and includes the following steps:

[0056] (1) When the reaction in the DETX synthesis reaction kettle is in the starting stage, close the gas inlet valve of the first tail gas absorption tower and open the gas inlet valve of the second tail gas absorption tower;

[0057] (2) When the reaction in the DETX synthesis reaction kettle enters the rapid reaction stage, open the gas inlet valve of the first tail gas absorption tower and close the gas inlet valve of the second tail gas absorption tower;

[0058] (3) When the reaction in the DETX synthesis reactor enters the reaction termination stage, close the gas inlet valve of the first tail gas absorption tower and open the gas inlet valve of the second tail gas absorption tower;

[0059] The absorption liquid of the first tail gas absorption tower is used as an oxidizing destroyer for the TPO synthesis reaction liquid.

[0060] The traditional method uses externally purchased sodium bisulfite as the oxidizing destroyer for the TPO synthesis reaction liquid. After the reaction, it is transformed into sodium sulfate waste salt, and then after sewage concentration and crystallization treatment, it is treated as hazardous waste; the external purchase cost of sodium bisulfite is relatively high; while the present invention adopts the above process, enabling the first tail gas absorption tower to absorb the tail gas with a high SO2 concentration and a low air concentration, thereby obtaining an absorption liquid rich in sodium bisulfite; using the second tail gas absorption tower to absorb the tail gas with a high air concentration and a low SO2 concentration, thereby avoiding the release of low-concentration SO2; adopting the above process reduces the generation of the absorption liquid rich in sodium bisulfate; and using the absorption liquid rich in sodium bisulfite as the oxidizing destroyer for the TPO synthesis reaction liquid reduces the treatment cost of high-salt waste liquid, and realizes the resource utilization of high-salt waste liquid, turning waste into treasure, reducing the procurement cost of sodium bisulfite as the TPO oxidizing destroyer, and having high economic and environmental benefits.

[0061] Preferably, the process of using the absorption liquid of the first tail gas absorption tower as the oxidizing destroyer for the TPO synthesis reaction liquid includes the following steps:

[0062] (a) Add the TPO synthesis reaction liquid into the TPO synthesis reaction liquid post-treatment kettle through the liquid inlet of the TPO synthesis reaction liquid post-treatment kettle, start the stirring paddle, and carry out stirring;

[0063] (b) Start the cooling jacket of the TPO synthesis reaction liquid post-treatment kettle to cool down the TPO synthesis reaction liquid post-treatment kettle;

[0064] (c) Under temperature control conditions, add the absorption liquid of the first tail gas absorption tower into the TPO synthesis reaction liquid post-treatment kettle through the absorption liquid inlet on the TPO synthesis reaction liquid post-treatment kettle, continue the temperature-controlled reaction, stand for heat preservation, and separate and remove the aqueous phase;

[0065] (d) Add the alkali liquid into the TPO synthesis reaction liquid post-treatment kettle through the alkali liquid inlet on the TPO synthesis reaction liquid post-treatment kettle, continue heat preservation and stirring, stand, and separate to obtain an organic phase containing TPO.

[0066] Here, the TPO synthesis reaction liquid refers to the reaction liquid obtained in the TPO oxidation section.

[0067] Preferably, in step (b), the temperature is reduced to 20°C to 30°C, such as 22°C, 24°C, 26°C or 28°C, etc.

[0068] In the present invention, the process of reacting the TPO synthesis reaction solution with the absorbent liquid in the first tail gas absorption tower is an exothermic process. To control the smooth progress of the process, the TPO synthesis reaction solution is cooled before adding the absorbent liquid, which is beneficial to the smooth progress of the oxidation reaction termination process.

[0069] Preferably, the method of adding the absorbent liquid of the first tail gas absorption tower into the TPO synthesis reaction solution post-treatment kettle through the absorbent liquid inlet on the TPO synthesis reaction solution post-treatment kettle in step (c) includes:

[0070] Transfer the absorbent liquid of the first tail gas absorption tower into the dropping tank through the liquid outlet of the first tail gas absorption tower and the liquid inlet of the dropping tank, and then drop it into the TPO synthesis reaction solution post-treatment kettle through the liquid outlet of the dropping tank and the absorbent liquid inlet of the TPO synthesis reaction solution post-treatment kettle.

[0071] Here, a dropping tank is used to add the absorbent liquid, which has the function of buffering the process, and at the same time is convenient for controlling the dropping rate to ensure the stable progress of the process.

[0072] Preferably, the temperature control range in step (c) is 20°C to 30°C, such as 22°C, 24°C, 26°C or 28°C, etc.

[0073] Preferably, the time for continued temperature control reaction in step (c) is 0.2 to 2 h, such as 0.5 h, 1 h or 1.5 h, etc.

[0074] Preferably, the time for static heat preservation in step (c) is 0.2 to 2 h, such as 0.5 h, 1 h or 1.5 h, etc.

[0075] Preferably, the method of separating and removing the aqueous phase in step (c) includes opening the valve at the bottom waste water outlet of the TPO synthesis reaction solution post-treatment kettle, transferring the aqueous phase to the waste water storage tank, and then closing the valve.

[0076] Preferably, the method of adding the alkali solution into the TPO synthesis reaction solution post-treatment kettle through the alkali solution inlet on the TPO synthesis reaction solution post-treatment kettle in step (d) includes:

[0077] Open the valve of the alkali solution dropping tank, and drop the alkali solution into the TPO synthesis reaction solution post-treatment kettle through the alkali solution inlet of the TPO synthesis reaction solution post-treatment kettle.

[0078] Preferably, the temperature for heat preservation and stirring in step (d) is 20°C to 28°C, such as 22°C, 24°C or 26°C, etc.

[0079] Preferably, the heat preservation and stirring time in step (d) is 0.2 h to 1.5 h, such as 0.5 h or 1 h, etc.

[0080] Preferably, the standing time in step (d) is 1 h to 1.5 h, such as 1.2 h or 1.4 h, etc.

[0081] Preferably, the liquid separation method in step (d) includes: opening the valve at the caustic scrubber outlet of the TPO synthesis reaction liquid post-treatment kettle, transferring the caustic scrubber liquid into the caustic scrubber liquid storage tank, and then switching to the discharging valve to transfer the organic phase containing TPO into the stripping kettle.

[0082] Preferably, the alkali solution in step (d) is selected from aqueous sodium hydroxide solution.

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] (1) The tail gas absorption and recycling device of the present invention segments and absorbs the tail gas generated in the DETX synthesis reaction kettle by setting up the first tail gas absorption tower and the second tail gas absorption tower, thereby obtaining an absorption liquid rich in sodium bisulfite, reducing the generation of high-salt wastewater containing sodium bisulfate, and reducing the treatment cost of high-salt waste liquid;

[0085] (2) The absorption liquid rich in sodium bisulfite obtained by the tail gas absorption and recycling device of the present invention can be used as an oxidizing destroyer for the TPO synthesis reaction liquid, reducing the procurement cost of sodium bisulfite;

[0086] (3) The tail gas absorption and recycling device of the present invention realizes the resource utilization of high-salt waste liquid. Description of the Drawings

[0087] Figure 1 is a schematic structural diagram of the tail gas absorption and recycling device in Embodiment 1 of the present invention;

[0088] Figure 2 is a schematic structural diagram of the tail gas absorption and recycling device in Embodiment 2 of the present invention;

[0089] 1 - First tail gas absorption tower, 2 - Second tail gas absorption tower, 3 - DETX synthesis reaction kettle, 4 - Three-way valve, 5 - Fan, 6 - Drop tank, 7 - TPO synthesis reaction liquid post-treatment kettle, 8 - Wastewater storage tank, 9 - Alkali solution drop tank, 10 - Caustic scrubber liquid storage tank, 11 - Cooling jacket, 12 - Stirring paddle. Detailed Embodiments

[0090] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0091] Embodiment 1

[0092] This embodiment provides a tail gas absorption and recycling device for synthesizing DETX, including:

[0093] A first tail gas absorption tower 1 and a second tail gas absorption tower 2;

[0094] The gas inlet of the first tail gas absorption tower 1 and the gas inlet of the second tail gas absorption tower 2 are connected to the gas outlet of the DETX synthesis reactor 3; the three are connected through a three-way valve 4; the tail gas generated by the DETX synthesis reactor is discharged from the gas outlet and enters the first tail gas absorption tower and the second tail gas absorption tower in stages;

[0095] A blower 5 is arranged between the gas outlet of the DETX synthesis reactor and the three-way valve;

[0096] The gas outlet of the first tail gas absorption tower is connected to the gas inlet of the second tail gas absorption tower;

[0097] A monitoring module for monitoring the foam height in the DETX synthesis reactor;

[0098] A control module for controlling the opening and closing states of the valves (three-way valves) of the gas inlets of the first tail gas absorption tower and the second tail gas absorption tower;

[0099] Both the first tail gas absorption tower and the second tail gas absorption tower are selected from spray towers; the spray liquid is selected from an aqueous sodium hydroxide solution with a concentration of 15wt% to 30wt%;

[0100] The tail gas absorption and recycling device further includes a drip tank 6, the liquid inlet of the drip tank 6 is connected to the liquid outlet of the first tail gas absorption tower 1, and the liquid outlet of the drip tank 6 is connected to the absorption liquid inlet of the TPO synthesis reaction liquid post-treatment kettle 7;

[0101] The tail gas absorption and recycling device further includes a waste water storage tank 8, and the bottom waste water outlet of the TPO synthesis reaction liquid post-treatment kettle 7 is connected to the waste water storage tank;

[0102] The tail gas absorption and recycling device further includes an alkali liquid drip tank 9, and the liquid outlet of the alkali liquid drip tank 9 is connected to the alkali liquid inlet of the TPO synthesis reaction liquid post-treatment kettle 7;

[0103] The tail gas absorption and recycling device further includes an alkali wash liquid storage tank 10, and the bottom alkali wash liquid outlet of the TPO synthesis reaction liquid post-treatment kettle 7 is connected to the alkali wash liquid storage tank 10;

[0104] The bottom of the TPO synthesis reaction liquid post-treatment kettle is provided with an organic phase discharge port;

[0105] The outside of the TPO synthesis reaction liquid post-treatment kettle is wrapped with a cooling jacket 11;

[0106] A stirring paddle 12 is provided in the TPO synthesis reaction liquid post-treatment kettle.

[0107] Example 2

[0108] The difference between this embodiment and embodiment 1 is that the tail gas absorption and recycling device comprises four parallel DETX synthesis reactors;

[0109] Asynchronous negative pressure feeding was used between the four DETX synthesis reactors;

[0110] Each DETX synthesis reactor is connected to its own fan and three-way valve; the intake direction of the tail gas is individually controlled by its own three-way valve.

[0111] Application Example 1

[0112] This application example uses Figure 2 The tail gas absorption and recycling device shown;

[0113] DETX synthesis reaction conditions: 180 kg of m-diethylbenzene was added to a DETX synthesis reactor, 150 kg of dithiosalicylic acid was added under stirring, the solid feed port was closed, 300 L of 98 wt% concentrated sulfuric acid was added under stirring, the reactor temperature was slowly raised to 95°C, and the reaction was kept at this temperature for 6 hours; SO2 was generated during the reaction and was removed to the tail gas absorption tower; the four DETX synthesis reactors were operated asynchronously; each DETX synthesis reactor was connected to the same first tail gas absorption tower and the second tail gas absorption tower;

[0114] The total volume of the reaction materials accounts for 40% of the volume of the DETX synthesis reactor;

[0115] In this application example, the interval in which the foam volume in the DETX synthesis reactor reaches more than 10% of the reactor volume is defined as the rapid reaction stage; that is, during the feeding stage and the reaction start stage, the gas outlet of the DETX synthesis reactor is connected to the gas inlet of the second tail gas absorption tower; when the foam height in the reactor rises to a level where its volume reaches 10% of the reactor volume, the three-way valve is switched so that the gas outlet of the DETX synthesis reactor is connected to the gas inlet of the first tail gas absorption tower, and when the bubble height in the reactor is reduced to 10% of the reactor volume, the three-way valve is switched so that the gas outlet of the DETX synthesis reactor is connected to the gas inlet of the second tail gas absorption tower. In order to maintain the air pressure in the DETX synthesis reactor, air can be added to the reactor after the second switching of the three-way valve;

[0116] The absorption liquid from the first tail gas absorption tower is transferred to the dripping tank;

[0117] An analysis of the components of the absorption liquid in the first tail gas absorption tower showed that sodium bisulfite accounted for 93% of the sulfur-containing salts.

[0118] The absorption liquid obtained from the first tail gas absorption tower in this application example is used as an oxidation destroyer in the TPO oxidation section; its operation includes the following steps:

[0119] Transfer the TPO synthesis reaction liquid in the TPO oxidation reactor to the TPO synthesis reaction liquid post-treatment kettle, start the stirring paddle to stir; and start the cooling jacket to cool down to 25 °C;

[0120] At 25 °C, drop the absorption liquid in the above dropping tank into the TPO synthesis reaction liquid post-treatment kettle. After the dropping is completed, close the dropping valve, continue to control the temperature and stir at 25 °C for 0.5 h, keep it static and warm for 0.5 h, and then discharge the aqueous phase from the bottom waste water outlet of the TPO synthesis reaction liquid post-treatment kettle; the aqueous phase enters the waste water storage tank;

[0121] Start stirring, add liquid caustic soda from the caustic soda dropping tank to the TPO synthesis reaction liquid post-treatment kettle. After the addition is completed, keep it warm and stir at 25 °C for 0.5 h. After the heat preservation is completed, turn off the stirring, keep it static for 1 h. After standing, discharge the caustic soda washing liquid from the caustic soda outlet valve and enter the caustic soda washing liquid storage tank; switch the valve, and discharge the organic phase containing TPO from the discharging valve and enter the stripping kettle for stripping.

[0122] Comparative Example 1

[0123] In this comparative example, the tail gas absorption device only includes the second tail gas absorption tower; that is, staged absorption is not carried out.

[0124] Using the tail gas absorption device in Comparative Example 1, with the operating conditions being exactly the same as those in Application Example 1, the components of the tail gas absorption liquid were tested. The proportion of sodium bisulfite in the sulfur-containing salt was only 13%; the absorption liquid obtained from the tail gas absorption tower could not be used as an oxidation destroyer in the TPO oxidation section.

[0125] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. An exhaust gas absorption and recycling device for synthesizing DETX, characterized in that, It includes a first tail gas absorption tower and a second tail gas absorption tower; The first tail gas absorption tower is used for absorbing the tail gas in the rapid reaction stage of the DETX synthesis reactor; The second tail gas absorption tower is used for absorbing the tail gas in the reaction start stage and the reaction termination stage of the DETX synthesis reactor, wherein, the first tail gas absorption tower is used to absorb the tail gas with a high SO2 concentration and a low air concentration in the rapid reaction stage; The second tail gas absorption tower is used to absorb the tail gas with a high air concentration and a low SO2 concentration in the reaction start stage and the reaction termination stage; wherein, through the absorption of the lye in the first tail gas absorption tower, an absorbent liquid rich in sodium bisulfite that can be recycled is obtained in the first tail gas absorption tower; The tail gas absorption recycling device further includes a monitoring module, and the monitoring module is used to monitor the height of the foam associated with the progress state of the reaction in the DETX synthesis reactor to judge the reaction stage.

2. The tail gas absorption and recycling device according to claim 1, wherein The gas inlet of the first tail gas absorption tower is connected to the gas outlet of the DETX synthesis reactor, and a valve is provided at the gas inlet of the first tail gas absorption tower; The gas inlet of the second tail gas absorption tower is connected to the gas outlet of the DETX synthesis reactor, and a valve is provided at the gas inlet of the second tail gas absorption tower.

3. The tail gas absorption and recycling device according to claim 2, characterized in that The gas inlet of the first tail gas absorption tower, the gas inlet of the second tail gas absorption tower and the gas outlet of the DETX synthesis reactor are connected through a multi-way valve.

4. The tail gas absorption and recycling device according to claim 2, characterized in that, The gas outlet of the first tail gas absorption tower is connected to the gas inlet of the second tail gas absorption tower.

5. The tail gas absorption and recycling device according to claim 1, wherein A fan is provided between the gas inlet of the first tail gas absorption tower and the gas outlet of the DETX synthesis reactor.

6. The tail gas absorption and recycling device according to claim 1, characterized in that, A fan is provided between the gas inlet of the second tail gas absorption tower and the gas outlet of the DETX synthesis reactor.

7. The tail gas absorption and recycling device according to claim 2, wherein, The tail gas absorption recycling device further includes a control module, and the control module is used to control the opening and closing states of the valves at the gas inlets of the first tail gas absorption tower and the second tail gas absorption tower.

8. The tail gas absorption and recycling device according to claim 1, wherein Both the first tail gas absorption tower and the second tail gas absorption tower are selected from spray towers.

9. The tail gas absorption and recycling device according to claim 8, characterized in that, The spray liquid of the spray tower is selected from lye with a concentration of 15wt% - 30wt%.

10. The tail gas absorption and recycling device according to claim 9, characterized in that, The lye is selected from aqueous sodium hydroxide solution.

11. The tail gas absorption and recycling device according to claim 1, wherein, The tail gas absorption recycling device further includes a post-treatment kettle for the TPO synthesis reaction liquid, and the liquid outlet of the first tail gas absorption tower is connected to the absorbent liquid inlet of the post-treatment kettle for the TPO synthesis reaction liquid.

12. The tail gas absorption and recycling device according to claim 11, characterized in that, The tail gas absorption recycling device further includes a drip tank, the liquid inlet of the drip tank is connected to the liquid outlet of the first tail gas absorption tower, and the liquid outlet of the drip tank is connected to the absorbent liquid inlet of the post-treatment kettle for the TPO synthesis reaction liquid.

13. The tail gas absorption and recycling device according to claim 11, characterized in that A waste water outlet is provided at the bottom of the post-treatment kettle for the TPO synthesis reaction liquid.

14. The tail gas absorption and recycling device according to claim 13, wherein The tail gas absorption recycling device further includes a waste water storage tank, and the bottom waste water outlet of the post-treatment kettle for the TPO synthesis reaction liquid is connected to the waste water storage tank.

15. The tail gas absorption and recycling device according to claim 11, characterized in that, An alkali liquid inlet is provided on the post-treatment kettle for the TPO synthesis reaction liquid.

16. The tail gas absorption and recycling device according to claim 15, characterized in that, The tail gas absorption recycling device further includes an alkali liquid drip tank, and the liquid outlet of the alkali liquid drip tank is connected to the alkali liquid inlet of the post-treatment kettle for the TPO synthesis reaction liquid.

17. The tail gas absorption and recycling device according to claim 15, characterized in that The tail gas absorption and recycling device further includes an alkali scrubbing solution storage tank, and the bottom alkali scrubbing solution outlet of the TPO synthesis reaction liquid post-treatment kettle is connected to the alkali scrubbing solution storage tank.

18. The tail gas absorption and recycling device according to claim 11, characterized in that, An organic phase discharge port is provided at the bottom of the TPO synthesis reaction liquid post-treatment kettle.

19. The tail gas absorption and recycling device according to claim 11, characterized in that, The outside of the TPO synthesis reaction liquid post-treatment kettle is wrapped with a cooling jacket.

20. The tail gas absorption and recycling device according to claim 11, characterized in that, A stirring paddle is arranged in the TPO synthesis reaction liquid post-treatment kettle.

21. The tail gas absorption and recycling device according to claim 11, wherein The reaction liquid inlet of the TPO synthesis reaction liquid post-treatment kettle is connected to the reaction liquid outlet of the TPO oxidation reaction kettle.

22. A tail gas absorption and recycling process for synthesizing DETX, characterized in that, The process uses the tail gas absorption and recycling device as described in any one of claims 1-21, and includes the following steps: (1) When the reaction in the DETX synthesis reaction kettle is in the starting stage, close the gas inlet valve of the first tail gas absorption tower and open the gas inlet valve of the second tail gas absorption tower; (2) When the reaction in the DETX synthesis reaction kettle enters the rapid reaction stage, open the gas inlet valve of the first tail gas absorption tower and close the gas inlet valve of the second tail gas absorption tower; (3) When the reaction in the DETX synthesis reaction kettle enters the reaction termination stage, close the gas inlet valve of the first tail gas absorption tower and open the gas inlet valve of the second tail gas absorption tower; The absorption liquid of the first tail gas absorption tower is used as an oxidation destroyer for the TPO synthesis reaction liquid.

23. The tail gas absorption and recycling process according to claim 22, characterized in that, The process of using the absorption liquid of the first tail gas absorption tower as an oxidation destroyer for the TPO synthesis reaction liquid includes the following steps: (a) Add the TPO synthesis reaction liquid into the TPO synthesis reaction liquid post-treatment kettle through the liquid inlet of the TPO synthesis reaction liquid post-treatment kettle, start the stirring paddle, and stir; (b) Start the cooling jacket of the TPO synthesis reaction liquid post-treatment kettle to cool the TPO synthesis reaction liquid post-treatment kettle; (c) Under temperature control conditions, add the absorption liquid of the first tail gas absorption tower into the TPO synthesis reaction liquid post-treatment kettle through the absorption liquid addition port on the TPO synthesis reaction liquid post-treatment kettle, continue the temperature-controlled reaction, stand and keep warm, and separate and remove the aqueous phase; (d) Add the alkali solution into the TPO synthesis reaction liquid post-treatment kettle through the alkali solution addition port on the TPO synthesis reaction liquid post-treatment kettle, continue to keep warm and stir, stand, and separate to obtain an organic phase containing TPO.

24. The tail gas absorption and recycling process according to claim 23, characterized in that, In step (b), cool down to 20°C to 30°C.

25. The tail gas absorption and recycling process according to claim 23, characterized in that, The method of adding the absorption liquid of the first tail gas absorption tower into the TPO synthesis reaction liquid post-treatment kettle in step (c) includes: Transfer the absorption liquid of the first tail gas absorption tower from the liquid outlet of the first tail gas absorption tower and the liquid inlet of the drip tank located between the first tail gas absorption tower and the TPO synthesis reaction liquid post-treatment kettle into the drip tank, and then drop it into the TPO synthesis reaction liquid post-treatment kettle through the liquid outlet of the drip tank and the absorption liquid addition port of the TPO synthesis reaction liquid post-treatment kettle.

26. The tail gas absorption and recycling process according to claim 23, characterized in that, The temperature range for temperature control in step (c) is 20°C to 30°C.

27. The tail gas absorption and recycling process according to claim 26, wherein The time for continuing the temperature-controlled reaction in step (c) is 0.2 to 2 hours.

28. The tail gas absorption and recycling process according to claim 27, wherein, The standing and heat preservation time in step (c) is 0.2 to 2 h.

29. The tail gas absorption and recycling process according to claim 23, characterized in that, The method for separating and removing the aqueous phase in step (c) includes opening the valve at the bottom waste water outlet of the post-treatment kettle for the TPO synthesis reaction solution, transferring the aqueous phase to the waste water storage tank, and then closing the valve.

30. The tail gas absorption and recycling process according to claim 23, characterized in that, The method for adding the lye into the post-treatment kettle for the TPO synthesis reaction solution in step (d) includes: Opening the valve connecting to the lye dropping tank on the post-treatment kettle for the TPO synthesis reaction solution, and dropping the lye into the post-treatment kettle for the TPO synthesis reaction solution through the lye addition port of the post-treatment kettle for the TPO synthesis reaction solution.

31. The tail gas absorption and recycling process according to claim 23, characterized in that, The temperature for heat preservation and stirring in step (d) is 20 to 28 °C.

32. The tail gas absorption and recycling process according to claim 31, characterized in that, The time for heat preservation and stirring in step (d) is 0.2 to 1.5 h.

33. The tail gas absorption and recycling process according to claim 32, characterized in that, The standing time in step (d) is 1 to 1.5 h.

34. The tail gas absorption and recycling process according to claim 23, characterized in that, The method for liquid separation in step (d) includes: opening the valve at the caustic wash solution outlet of the post-treatment kettle for the TPO synthesis reaction solution, transferring the caustic wash solution into the caustic wash solution storage tank connected to the post-treatment kettle for the TPO synthesis reaction solution, and then switching to the discharging valve to transfer the organic phase containing TPO into the stripping kettle.

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