System for recovering epoxide from tail gas
By setting up two-stage absorption towers in the recycling system and increasing the intake pipe diameter, the problem of incomplete epoxide absorption in the exhaust gas is solved, and more efficient epoxide recovery and environmental protection requirements are achieved.
Patent Information
- Application Number
- CN202421195266.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-29
- Publication Date
- 2025-02-18
- Estimated Expiration
- 2034-05-29
AI Technical Summary
The prior art has problems such as slow reaction, difficulty in removing acidic catalysts, difficulty in using products, incomplete absorption of exhaust gas, and insufficient epoxide content in the released exhaust gas.
The two-stage absorption tower is used to add a second-stage absorption tower, and its exhaust gas intake pipe is changed to the top of the absorption tower. The diameter of the intake pipe is increased from 20mm of the first-stage tower to 80mm to achieve reabsorption of excess epoxide.
Through the installation of the two-stage absorption tower, the epoxide in the exhaust gas is achieved, which meets environmental protection requirements, and the absorption efficiency is improved by thickening the absorption tube.
Smart Images
Figure CN222489522U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of recycling epoxides, and more specifically relates to a system for recycling epoxides from tail gas. Background Art
[0002] Epoxides are ether compounds containing oxygen three-membered rings, in which the three atoms are roughly on the plane of an equilateral triangle structure. Due to the large tension, epoxy compounds are more active than other ethers, especially reacting with nucleophilic reagents. Ethylene oxide and propylene oxide are the simplest epoxy compounds. Both are low-boiling liquids at room temperature and are toxic substances that can cause damage to the eyes, skin, and respiratory tract. Both have active chemical properties and can react with many kinds of compounds. They are important chemical raw materials and organic synthesis intermediates. There are existing technologies that disclose methods for recovering epoxides in tail gas, but they have the disadvantages of slow reaction, difficult removal of acidic catalysts in the product, difficult product utilization, incomplete tail gas absorption, and the epoxide content in the released tail gas cannot meet environmental monitoring requirements. Utility Model Content
[0003] In view of this, the main purpose of the utility model is to provide a system for recovering epoxides from exhaust gas. The technical problem to be solved is to add a secondary absorption tower and change the exhaust gas inlet pipe of the secondary tower to the top of the absorption tower, and increase the diameter of the inlet pipe from 20mm of the primary tower to 80mm, so that the excess epoxides can be absorbed again.
[0004] The purpose of the utility model and the technical problems solved are achieved by adopting the following technical solutions. The utility model proposes a system for recovering epoxides from tail gas, comprising a primary absorption tower and a secondary absorption tower connected to each other; a gas distributor is arranged at the lower part of the primary absorption tower, a secondary absorption filler layer is arranged at the upper part of the primary absorption tower, an inlet for tail gas containing epoxides is opened at one side of the primary absorption tower, a secondary absorption liquid inlet is opened at one end of the top of the primary absorption tower, and a secondary absorption liquid circulation outlet is opened at the bottom of the primary absorption tower; a gas distributor is arranged at the lower part of the secondary absorption tower, a quadruple absorption filler layer is arranged at the upper part of the secondary absorption tower, an inlet for tail gas containing epoxides after secondary absorption is opened at the top of the secondary absorption tower, four secondary absorption liquid inlets are opened at the top of the secondary absorption tower, and four secondary absorption liquid circulation outlets are opened at the bottom of the secondary absorption tower.
[0005] Preferably, in the aforementioned system for recovering epoxides from tail gas, the secondary absorption liquid circulation outlet is connected to a heat exchanger via a pipeline, and the heat exchanger is also connected to the top of the primary absorption tower via a pipeline.
[0006] Preferably, in the aforementioned system for recovering epoxide from tail gas, the secondary absorption liquid circulation outlet is also connected to a post-treatment reactor through a pipeline.
[0007] Preferably, in the aforementioned system for recovering epoxide from tail gas, a circulation pump is provided on the pipeline between the secondary absorption liquid circulation outlet and the post-treatment reactor.
[0008] Preferably, in the aforementioned system for recovering epoxides from tail gas, the top of the primary absorption tower is also connected to the gas distributor in the secondary absorption tower through a pipeline.
[0009] Preferably, in the aforementioned system for recovering epoxides from tail gas, the top of the secondary absorption tower is connected to an exhaust device.
[0010] Preferably, in the aforementioned system for recovering epoxide from tail gas, the circulation outlet of the quaternary absorption liquid is connected to the heat exchanger through a pipeline, and the heat exchanger is also connected to the inlet of the quaternary absorption liquid through a pipeline.
[0011] Preferably, in the aforementioned system for recovering epoxide from tail gas, a circulation pump is provided on the pipeline between the circulation outlet of the fourth absorption liquid and the heat exchanger.
[0012] Preferably, in the aforementioned system for recovering epoxide from tail gas, the gas distributor is a porous plate distributor; the porous plate distributor is a stainless steel plate with a plurality of 5 mm holes dispersed thereon.
[0013] Preferably, in the aforementioned system for recovering epoxides from tail gas, the diameter of the air inlet pipe of the secondary absorption tower or the air outlet pipe of the primary absorption tower is 80 mm.
[0014] Compared with the prior art, the system for recovering epoxide from tail gas described in the utility model has the following beneficial effects:
[0015] The utility model adopts the setting of two-stage absorption towers to make the absorption of epoxides in tail gas more thorough and more in line with the current environmental protection requirements; at the same time, the tail gas absorption pipe is thickened, which is more conducive to the absorption of epoxides in tail gas.
[0016] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the preferred embodiments of the utility model are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the structure of a system for recovering epoxide from tail gas provided by the utility model;
[0018] Figure numerals: 1-primary absorption tower; 2-secondary absorption packing layer; 3-secondary absorption epoxide-containing tail gas outlet; 4-secondary absorption liquid inlet; 5-epoxide-containing tail gas inlet; 6-heat exchanger; 7-post-treatment reactor; 8-circulation pump; 9-secondary absorption liquid circulation outlet; 10-gas distributor; 11-secondary absorption tower; 12-fourth absorption packing layer; 13-fourth absorption exhaust device; 14-fourth absorption liquid inlet; 15-epoxide-containing tail gas inlet after secondary absorption; 16-fourth absorption liquid circulation outlet. DETAILED DESCRIPTION
[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.
[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0021] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0022] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0023] Unless otherwise specified, the materials, reagents, etc. involved below are all commercially available products well known to those skilled in the art; unless otherwise specified, the methods described are all methods well known in the art. Unless otherwise defined, the technical terms or scientific terms used should have the usual meanings understood by ordinary technicians in the field to which the utility model belongs. If no specific experimental steps or conditions are specified below, the operations or conditions of the conventional experimental steps described in the literature in the field can be followed.
[0024] like Figure 1 As shown, some embodiments of the utility model provide a system for recovering epoxide from tail gas, including a primary absorption tower 1 and a secondary absorption tower 11 connected to each other; a gas distributor 10 is arranged at the lower part of the primary absorption tower 1, a secondary absorption filler layer 2 is arranged at the upper part of the primary absorption tower 1, a tail gas inlet 5 containing epoxide is opened on one side of the primary absorption tower 1, a secondary absorption liquid inlet 4 is opened at one end of the top of the primary absorption tower 1, and a secondary absorption liquid circulation outlet 9 is opened at the bottom of the primary absorption tower 1; a gas distributor 10 is arranged at the lower part of the secondary absorption tower 11, a quaternary absorption filler layer 12 is arranged at the upper part of the secondary absorption tower 11, a tail gas inlet 15 containing epoxide after secondary absorption is opened at the top of the secondary absorption tower 11, a quaternary absorption liquid inlet 14 is opened at the top of the secondary absorption tower 11, and a quaternary absorption liquid circulation outlet 16 is opened at the bottom of the secondary absorption tower 11. By adding the setting of the secondary absorption tower 11, the epoxide not absorbed by the primary absorption tower 1 can be fully absorbed, the profit can be increased, and the pollution can be reduced at the same time. The secondary absorption filler layer 2 and the fourth absorption filler layer are both made of stainless steel corrugated fillers.
[0025] In the above technical scheme, in order to facilitate operation and prevent incomplete absorption of tail gas, a secondary absorption tower 11 is added and the tail gas inlet pipe of the secondary absorption tower 11, i.e., the four-time absorption exhaust device 13, is changed to the top of the absorption tower, and the diameter of the inlet pipe is increased from DN-20 (pipe diameter is 20mm) of the primary absorption tower 1 to DN-80 (pipe diameter is 80mm), so that the excess epoxide can be well absorbed again, and the discharged tail gas can meet the standards for permitted emissions regardless of whether it is the workshop's own online detection or the environmental protection regular sampling detection. The absorption liquid of the secondary absorption tower 11 can be poured into the primary absorption tower 1 for continued absorption, which not only speeds up the absorption time of the primary absorption tower 1, but also ensures the freshness of the absorption liquid in the secondary absorption tower 11, which is more conducive to the complete absorption of epoxide. For this reason, the diameter of the inlet pipe of the secondary absorption tower or the outlet pipe of the primary absorption tower is set to 80mm.
[0026] In some embodiments, optionally, the secondary absorption liquid circulation outlet 9 is connected to the heat exchanger 6 through a pipeline, and the heat exchanger 6 is also connected to the top of the primary absorption tower 1 through a pipeline. Through the heat exchanger 6, the absorption liquid is heated to 50-60°C by utilizing the heat absorbed by the deionized water in the heat exchanger during the reaction of the ethoxylation device, which is more conducive to the absorption of epoxides. At the same time, the lowering of the water temperature in the heat exchanger is more conducive to the cooling of the materials in the ethoxylation reactor, and the temperature of the absorption liquid is controlled by adjusting it.
[0027] In some embodiments, optionally, the secondary absorption liquid circulation outlet 9 is also connected to the post-processing reactor 7 through a pipeline. After the absorption liquid reaches the water content index, it can be directly pressed into the post-processing reactor for treatment, thereby saving time and manpower.
[0028] In some embodiments, optionally, a circulation pump 8 is provided on the pipeline between the secondary absorption liquid circulation outlet 9 and the post-treatment reactor 7. Circulation by the circulation pump is more conducive to the uniformity of the upper and lower layers of the absorption liquid, prevents uneven concentration of the absorption liquid, and is also more conducive to the absorption of epoxide.
[0029] In some embodiments, optionally, the top of the primary absorption tower 1 is also connected to the gas distributor 10 in the secondary absorption tower 11 through a pipeline. The tail gas after secondary absorption in the primary absorption tower 1 enters the gas distributor 10 of the secondary absorption tower 11 from the top pipeline of the primary absorption tower 1 for tertiary absorption of epoxide.
[0030] In some embodiments, optionally, the top of the secondary absorption tower 11 is connected with a four-time absorption exhaust device 13. The four-time absorption exhaust device 13 is used to directly discharge the VOC content in the tail gas to the atmosphere after the tail gas is absorbed four times and reaches the emission standard required by environmental protection.
[0031] In some embodiments, optionally, the quaternary absorption liquid circulation outlet 16 is connected to the heat exchanger 8 through a pipeline, and the heat exchanger 8 is also connected to the quaternary absorption liquid inlet 14 through a pipeline. Through the heat exchanger 8, the absorption liquid is heated to 50-60° C. by utilizing the heat absorbed by the deionized water in the heat exchanger during the reaction of the ethoxylation device, which is more conducive to the absorption of epoxides. At the same time, the lowering of the water temperature in the heat exchanger is more conducive to the cooling of the materials in the ethoxylation reactor, and the temperature of the absorption liquid is controlled by adjusting it.
[0032] In some embodiments, optionally, a circulation pump 8 is provided on the pipeline between the fourth absorption liquid circulation outlet 16 and the heat exchanger 6. The absorption liquid can be circulated up and down by the circulation pump 8, which is more conducive to the absorption of epoxide.
[0033] In some embodiments, optionally, the gas distributor 10 may be a porous plate distributor; the porous plate distributor is a stainless steel plate with a plurality of 5 mm holes dispersed thereon.
[0034] In some embodiments, optionally, a quadruple absorption exhaust device 13 is provided at the top of the secondary absorption tower 11 .
[0035] like Figure 1 As shown, some embodiments of the present invention also provide a method for recovering epoxide from tail gas, comprising the following steps:
[0036] The tail gas containing epoxide first passes through the gas distributor 10 at the lower part of the primary absorption tower 1 to complete an absorption reaction; specifically, the tail gas containing epoxide comes from the connection part between the ethoxylation device reactor or the epoxide storage tank and the epoxide metering tank and the tail gas recovery device; the tail gas containing epoxide passes through the gas distributor at a rate of 20m / s. 3 / h-600m 3 / h, the gas distributor can disperse the tail gas, increase the contact area between the tail gas and the absorption liquid, and be more conducive to the absorption of epoxides in the tail gas; the volume concentration of epoxides in the tail gas containing epoxides is 5%-55%, and the components are ethylene oxide, propylene oxide or a mixture of ethylene oxide and propylene oxide. The gas distributor 10 can be a porous plate distributor; the porous plate distributor is a stainless steel plate with a plurality of 5mm holes dispersed thereon. After the epoxide-containing tail gas enters the distributor, it is dispersed layer by layer, and the flow rate is reduced, making it easier to be absorbed by the absorption liquid. The filler in the primary absorption tower 1 is a stainless steel corrugated filler, which is used to disperse the absorption liquid, so that the dispersed absorption liquid is easier to react with the epoxides in the primary absorption tower; the temperature of the primary absorption reaction is controlled by a heat exchanger connected in series with the external circulation pipeline;
[0037] After the primary absorption, the tail gas containing epoxide (which is composed of ethylene oxide, propylene oxide or a mixture of the two, with a volume concentration of 5%-40%) passes through the secondary absorption filler 2 at the top of the primary absorption tower 1, and is continuously countercurrent washed by the absorbent (the absorbent is an organic amine solution with a solution concentration of 30wt%-60wt%) to complete the secondary absorption reaction; the continuous countercurrent washing is: the absorbent is circulated by a circulation pump, the absorbent flows from top to bottom, and the tail gas containing epoxide flows from bottom to top, thereby achieving a countercurrent absorption effect. Specifically, monoethanolamine and deionized water are sequentially pumped into the absorption tower in proportion, and then circulated evenly by a circulation pump to obtain the absorbent, and then the absorption of epoxide begins. The reaction process of monoethanolamine and epoxide is as follows:
[0038]
[0039]
[0040] The tail gas after the absorption reaction (which is composed of ethylene oxide, propylene oxide or a mixture of the two, with a volume concentration of 2%-20%) enters the secondary absorption tower 11, and directly enters the gas distributor 10 at the lower part of the secondary absorption tower 11 through a thickened pipeline to complete the three absorption reactions. The diameter of the thickened pipeline is 80 mm, which is convenient for the tail gas to pass through. The increase in the diameter of the pipeline increases the gas-liquid contact area, making the reaction more complete. By thickening the air inlet pipeline, the contact area between the epoxide in the tail gas and the absorption liquid is increased, which better promotes the reaction and makes the reaction more complete.
[0041] The tail gas of the epoxide after the three absorptions passes through the upper four-absorption filler 12 in the secondary absorption tower 11 (which is a stainless steel corrugated filler, used to disperse the absorption liquid, so that the dispersed absorption liquid and the epoxide in the absorption tower are more convenient to react), and is continuously countercurrent washed by the absorption liquid to complete the four absorption reactions; the tail gas of the epoxide after the three absorptions is composed of ethylene oxide and a trace amount of propylene oxide, and its volume concentration is 1%-8%. The continuous countercurrent washing is to circulate the absorption liquid through a circulation pump, the absorption liquid flows from top to bottom, and the tail gas containing epoxide flows from bottom to top, so as to achieve the countercurrent absorption effect.
[0042] The tail gas after the above four absorption reactions is discharged through the exhaust device 13. The VOC value detected by the real-time monitoring device is less than 80mg / m 3 , can be discharged directly into the atmosphere.
[0043] In the specific implementation, when the moisture content of the secondary absorption liquid in the primary absorption tower 1 is reduced to 15wt% (determined by Karl Fischer method), a batch of recovery reactions is terminated, and the absorption liquid in the primary absorption tower 1 is poured into the post-treatment reactor through a pipeline for post-treatment, and the absorption liquid in the secondary absorption tower 11 is poured into the primary absorption tower 1 through a pipeline, and the secondary absorption tower 11 is replaced with a new absorption liquid. The pouring into the post-treatment reactor for post-treatment specifically includes: pouring the absorption liquid into the post-treatment reactor, heating to 65-70°C for aging for 30 minutes under nitrogen protection, and then vacuum dehydrating and degassing at 65-70°C for 30 minutes, cooling to about 50°C to obtain the finished product. Pouring the absorption liquid through the pipeline not only saves manpower, but also facilitates operation, and directly pouring it through the pipeline can minimize the absorption liquid from contacting the air, thereby preventing the absorption liquid from turning yellow.
[0044] The present invention is further described below in conjunction with specific embodiments.
[0045] Example 1
[0046] 30m 3 Ethylene oxide storage tank, 20m3 The propylene oxide storage tank is connected to the tail gas recovery device, 1260 kg of monoethanolamine and 900 kg of deionized water are added to the primary absorption tower 1 and the secondary absorption tower 11 in sequence, and the circulation pump 8 is turned on for material circulation. The flow rate of the circulation pump 8 is 20m 3 / hour; the temperature of the circulating pipeline is controlled at 50-60°C through the heat exchanger 6, and the tail gas absorption reaction begins; the tail gas flow rate of the primary absorption tower 1 is an average of 18m 3 / hour, the average volume concentration of epoxide is 25%; after the epoxide in the tail gas is absorbed once and twice in the primary absorption tower 1, it enters the secondary absorption tower 11 through the top pipeline of the primary absorption tower 1; the average tail gas flow rate of the secondary absorption tower 11 is 13m 3 / hour, the average volume concentration of epoxide is 10%; the epoxide in the tail gas is directly discharged through the exhaust device after the third and fourth absorption in the secondary absorption tower 11. After 40 days, the water content in the secondary absorption liquid of the primary absorption tower 1 is 19.63% by Karl Fischer method, and the recovery reaction of this batch of the primary absorption tower 1 is terminated. Figure 1 .
[0047] The secondary absorption liquid is pumped into the post-treatment reactor 7, heated to 62°C for aging for 30 minutes under nitrogen protection, then vacuum dehydrated and degassed for 30 minutes at the same temperature, cooled to about 50°C for discharging, and a nearly colorless aqueous solution of a mixture of monoethanolamine, diethanolamine and diethanolmonoisopropanolamine is obtained.
[0048] The obtained product was measured according to HG / T 3268-2002 "Industrial Triethanolamine", where the content of diethanol monoisopropanolamine was 60.2wt%, diethanolamine content was 12.5wt%, and monoethanolamine content was 6.3wt%. The obtained product was directly used as cement grinding aid, cement production increased by 3wt%, and energy consumption per ton of cement was reduced by 4%; used as concrete admixture, the compressive strength was significantly improved at 7 days, 28 days, and 90 days.
[0049] At the same time, the water content of the fourth absorption liquid in the secondary absorption tower 11 is 38.12wt% determined by Karl Fischer method, and it is discharged and poured into the primary absorption tower 1 for further absorption. At the same time, 1260kg of monoethanolamine and 900kg of deionized water are pumped into the secondary absorption tower 11 for further absorption.
[0050] After 40 days of absorption, the VOC value of tail gas discharged into the atmosphere was monitored online at 40-75 mg / m 3 , in line with environmental protection requirements.
[0051] Example 2: 5m 3 Absorption of epoxides in external circulation ethoxylation and propoxylation units
[0052] Connect the reaction kettle of the external circulation ethoxylation propoxylation unit, the ethylene oxide and propylene oxide metering tanks and the tail gas recovery unit together, and guide the production exhaust gas to the tail gas recovery unit;
[0053] 1680kg monoethanolamine and 1100kg deionized water are added to the primary absorption tower 1 and the secondary absorption tower 11, and the circulation pump 8 is turned on for material circulation. The flow rate of the circulation pump 8 is 25m 3 / hour; the temperature of the circulating pipeline is controlled at 50-60°C through the heat exchanger 6, and the tail gas absorption reaction begins; the tail gas flow rate of the primary absorption tower 1 is an average of 20m 3 / hour, the average volume concentration of epoxide is 35%; after the epoxide in the tail gas is absorbed once and twice in the primary absorption tower 1, it enters the secondary absorption tower 11 through the top pipeline of the primary absorption tower 1; the average tail gas flow rate of the secondary absorption tower 11 is 14m 3 / hour, the average volume concentration of epoxides was 13%; the epoxides in the tail gas were directly discharged through the exhaust device after being absorbed three times and four times in the secondary absorption tower 11. After 14 days, the water content in the secondary absorption liquid of the primary absorption tower 1 was determined by the Karl Fischer method to be 15.72%, and the recovery reaction of this batch of the primary absorption tower 1 was terminated. Figure 1 .
[0054] The secondary absorption liquid was pumped into the post-treatment reactor 7, heated to 60°C for aging for 30 minutes under nitrogen protection, then vacuum dehydrated and degassed for 30 minutes at the same temperature, cooled to about 50°C for discharging, and a yellowish aqueous solution of a mixture of monoethanolamine, diethanolamine and monoethanoldiisopropanolamine was obtained.
[0055] The obtained product was measured according to HG / T 3268-2002 "Industrial Triethanolamine", where the content of monoethanol diisopropanolamine was 64.54wt%, the content of diethanolamine was 13.3wt%, and the content of monoethanolamine was 7.1wt%. The obtained product was directly used as cement grinding aid, the cement output increased by 2.5wt%, and the energy consumption per ton of cement was reduced by 3.5%; used as concrete admixture, the compressive strength was significantly improved at 7 days, 28 days, and 90 days.
[0056] At the same time, the water content of the fourth absorption liquid in the secondary absorption tower 11 is 35.56% by Karl Fischer method, and it is discharged and poured into the primary absorption tower 1 for further absorption. At the same time, 1680 kg of monoethanolamine and 1100 kg of deionized water are pumped into the secondary absorption tower 11 for further absorption.
[0057] After 14 days of absorption, the VOC value of tail gas discharged into the atmosphere was monitored online at 35-70 mg / m 3 , in line with environmental protection requirements.
[0058] Example 3: 3m3 Absorption of Epoxides in Stirred Ethoxylation Plants
[0059] Connect the stirred ethoxylation unit reactor, ethylene oxide metering tank and tail gas recovery device together, and lead the production exhaust gas to the tail gas recovery device; add 1050kg monoethanolamine and 800kg deionized water to the primary absorption tower 1 and the secondary absorption tower 11, and start the circulation pump 8 for material circulation. The flow rate of the circulation pump 8 is 12m 3 / hour; the temperature of the circulating pipeline is controlled at 50-60°C through the heat exchanger 6, and the tail gas absorption reaction begins; the tail gas flow rate of the primary absorption tower 1 is an average of 12m 3 / hour, the average volume concentration of ethylene oxide is 30%; after the epoxide in the tail gas is absorbed once and twice in the primary absorption tower 1, it enters the secondary absorption tower 11 through the top pipeline of the primary absorption tower 1; the average tail gas flow rate of the secondary absorption tower 11 is 8m 3 / hour, the average volume concentration of epoxide is 9%; the epoxide in the tail gas is directly discharged through the exhaust device after being absorbed three times and four times in the secondary absorption tower 11. After 30 days, the water content in the secondary absorption liquid of the primary absorption tower was determined by Karl Fischer method to be 17.72%, and the recovery reaction of this batch of the primary absorption tower 1 was terminated. Figure 1 .
[0060] The secondary absorption liquid is pumped into the post-treatment reactor 7, heated to 65°C for aging for 30 minutes under nitrogen protection, then vacuum dehydrated and degassed for 30 minutes at the same temperature, cooled to about 50°C for discharging, and a nearly colorless aqueous solution of a mixture of monoethanolamine, diethanolamine and triethanolamine is obtained.
[0061] The obtained product was measured according to HG / T 3268-2002 "Industrial Triethanolamine", where the triethanolamine content was 58.98wt%, the diethanolamine content was 16.83wt%, and the monoethanolamine content was 6.4wt%. The obtained product was directly used as a cement grinding aid, which increased cement production by 3.1wt% and reduced energy consumption per ton of cement by 3.4wt%; used as a concrete admixture, the compressive strength was significantly improved at 7 days, 28 days, and 90 days.
[0062] At the same time, the water content of the fourth absorption liquid in the secondary absorption tower 11 is 37.83wt% determined by Karl Fischer method, and it is discharged and poured into the primary absorption tower 1 for further absorption. At the same time, 1050kg of monoethanolamine and 800kg of deionized water are pumped into the secondary absorption tower 11 for further absorption.
[0063] After 30 days of absorption, the VOC value of tail gas discharged into the atmosphere was monitored online at 37-72 mg / m 3 , in line with environmental protection requirements.
[0064] In the specification of the present utility model, a lot of specific details are described. However, it is understood that the embodiments of the present utility model can be practiced without these specific details. In some embodiments, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this specification.
[0065] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present utility model will not further describe various possible combinations.
[0066] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.
[0067] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.
Claims
1. A system for recovering epoxide from tail gas, characterized in that: The invention comprises a primary absorption tower and a secondary absorption tower which are connected to each other; a gas distributor is arranged at the lower part of the primary absorption tower, a secondary absorption filler layer is arranged at the upper part of the primary absorption tower, an inlet for tail gas containing epoxide is opened at one side of the primary absorption tower, a secondary absorption liquid inlet is opened at one end of the top of the primary absorption tower, and a secondary absorption liquid circulation outlet is opened at the bottom of the primary absorption tower; a gas distributor is arranged at the lower part of the secondary absorption tower, a quaternary absorption filler layer is arranged at the upper part of the secondary absorption tower, an inlet for tail gas containing epoxide after secondary absorption is opened at the top of the secondary absorption tower, four absorption liquid inlets are opened at the top of the secondary absorption tower, and four absorption liquid circulation outlets are opened at the bottom of the secondary absorption tower.
2. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The secondary absorption liquid circulation outlet is connected to the heat exchanger through a pipeline, and the heat exchanger is also connected to the top of the primary absorption tower through a pipeline.
3. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The secondary absorption liquid circulation outlet is also connected to the post-treatment reactor through a pipeline.
4. A system for recovering epoxide from tail gas as claimed in claim 3, characterized in that: A circulation pump is arranged on the pipeline between the secondary absorption liquid circulation outlet and the post-treatment reactor.
5. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The top of the primary absorption tower is also connected to the gas distributor in the secondary absorption tower through a pipeline.
6. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The top of the secondary absorption tower is connected with a quadruple absorption exhaust device.
7. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The fourth absorption liquid circulation outlet is connected to the heat exchanger through a pipeline, and the heat exchanger is also connected to the fourth absorption liquid inlet through a pipeline.
8. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: A circulation pump is arranged on the pipeline between the fourth absorption liquid circulation outlet and the heat exchanger.
9. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The gas distributor is a porous plate distributor; the porous plate distributor is a stainless steel plate with a plurality of 5 mm holes dispersed thereon.
10. A system for recovering epoxide from tail gas as claimed in claim 1, characterized in that: The diameter of the air inlet pipe of the secondary absorption tower or the air outlet pipe of the primary absorption tower is 80 mm.