Full-line device and method for drying air and air separation gas by using Reline deep eutectic solvent
Through the full-line device and process flow of Reline deep eutectic solvent, the problems of adsorbent deactivation and absorption method in air drying are solved, and low-energy consumption and high-efficiency air drying is achieved, which conforms to the principle of green chemistry and degradation of Reline Good performance, low raw material cost, significantly improving drying effect.
Patent Information
- Application Number
- CN202411677433.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-01-07
AI Technical Summary
In the existing air drying technology, the adsorption method has problems of adsorbent deactivation and high cost, while the absorption method faces the high energy consumption problems of the secondary volatility of the solvent and the water separation process, and lacks environmentally friendly alternative solvents.
Using Reline deep eutectic solvent as dehydrating agent, the drying of air and air-divided gases is achieved by designing a full-line device and process flow, including synthesis, purification, filler absorption tower, recovery flash evaporation tower, heat exchanger and other equipment. Reline has high hygroscopicity and low volatility, reducing energy consumption and improving drying effect.
It achieves low energy consumption and efficient air drying, reduces the energy consumption of the secondary volatilization and recovery process of solvents, complies with the principle of green chemistry, and has good degradability and low raw material costs, which significantly improves the drying effect.
Smart Images
Figure CN119258741A_ABST
Abstract
Description
[Technical field]
[0001] The present application discloses a device and method for removing moisture from air and air separation gas by using a solvent absorption method and Reline deep eutectic solvent as a desiccant, and belongs to the technical field of chemical separation and purification. [Background technology]
[0002] Gas drying is a basic and common industrial process, and it plays a central role in my country's chemical industry production. Air and air separation gas are one of the most important bulk gases, and are widely used in industries such as industry, medicine and food. In the process of air production and air separation, the moisture in the air will corrode the separation agent (generally molecular sieves for pressure swing adsorption), equipment and pipelines in the separation process, and will also affect the purity and quality of subsequent products, which will have an adverse effect on the use of subsequent products. Therefore, it is necessary to dry the air in the pre-process.
[0003] At present, there are two main methods for air drying in industry: adsorption and absorption. The adsorption method uses porous materials such as molecular sieves, silica gel and activated carbon as adsorbents, and completes the air drying process through pressure swing adsorption and other forms. This method has the advantages of high efficiency, wide application scenarios and simple principle, but there are generally stability problems. Especially when running for a long time in the industrial process, the adsorbent is easily deactivated, and the cost of drying industrial gas by adsorption is high. Especially in intermittent operation, additional complex system design is required to save operating costs. The absorption method is widely used to treat high-flux gases. The principle of the absorption method is to use a hygroscopic solvent and the gas to be dried in the absorption tower for gas-liquid countercurrent mass transfer, so that the moisture in the gas is effectively removed. The advantages of the absorption method are low cost, large processing capacity, continuous operation, and high long-term operation stability. In industry, some high-boiling point alcohols are generally used as dehydrating agents, such as diethylene glycol, triethylene glycol and DSMO. Although such dehydrating agents have a high boiling point, they still have certain volatility during production and use. Therefore, the absorption method inevitably has the disadvantage of secondary volatilization of the solvent. At the same time, since the dehydrating agent must be recycled, the high energy consumption of the water and alcohol separation process is also a problem faced by the absorption method.
[0004] The core of both absorption and adsorption methods lies in the performance of absorbents / adsorbents. The research on absorbents has always been a hot topic. As a molten salt at room temperature, ionic liquids are considered to be an ideal solvent because of their non-volatility and designability. The high cost, difficulty in industrial synthesis and unknown environmental degradability of ionic liquids limit their large-scale application. Deep eutectic solvents are a complex synthesized by hydrogen bond donors and hydrogen bond acceptors in a certain proportion. They have similar properties to ionic liquids and are therefore considered to be a substitute for ionic liquids. At the same time, deep eutectic solvents also have the advantages of low raw material cost, simple synthesis and easy degradation. Therefore, deep eutectic solvents are considered to be a green and ideal solvent. Due to the strong polarity of deep eutectic solvents and their complex hydrogen bond network, they obviously have a strong affinity with water, so deep eutectic solvents are likely to be a potential viable dehydrating agent.
[0005] Reline is the first deep eutectic solvent to be proposed and the most widely studied. It has properties similar to ionic liquids, but its properties are stable, its synthesis is simple, its raw materials are economical and readily available, and its cost is only 1 / 10 of that of ionic liquids. The essence of the gas drying process is to remove water vapor from volatile gases. Reline itself has a complex hydrogen bond network and has extremely strong hygroscopicity and water capacity. First, the solubility and selectivity of water, air, oxygen and nitrogen in Reline were calculated using the COSMO-SAC model, proving that Reline is theoretically feasible for drying air and air separation gases. [Summary of the invention]
[0006] The purpose of the present invention is to synthesize Reline deep eutectic solvent as a dehydrating agent to replace traditional organic solvents and apply it to the drying process of air and air separation gas. The present invention takes into account the green nature of Reline and its potential feasibility for dehydration, and designs a full-line device and process flow for drying air and air separation gas in industry according to the synthesis process and physicochemical properties of Reline. Through experimental and computational research, it is found that the method has the advantages of excellent drying performance, low energy consumption of the device, etc., which is in line with the principles of green chemistry and has significant advantages over existing processes.
[0007] The present invention is achieved through the following technical solutions.
[0008] A full-line device for drying air and air separation gas using a Reline deep eutectic solvent, characterized in that it comprises a Reline synthesis reaction tank (B1), a Reline purification flash tank (F1), a packed absorption tower (T1), a Reline recovery flash tower (F2), a heat exchanger (E1), a heater (H1), a first condenser (C1), a second condenser (C2), and a third condenser (C3); the Reline synthesis reaction tank (B1) is provided with an inlet for choline chloride (S1) and urea (S2), and a fresh Reline deep eutectic solvent is provided at the bottom of the Reline synthesis reaction tank (B1). The eutectic solvent (S3) outlet, the fresh Reline deep eutectic solvent (S3) outlet is connected to the feed port of the Reline purification flash tank (F1) through a pipeline, the Reline purification flash tank (F1) is provided with a flash steam (S4) outlet on the top, the flash steam (S4) outlet is connected to the first condenser (C1), the condensed water (S5) outlet corresponding to the first condenser is connected to the water inlet of the heat exchanger (E1) through a pipeline, the water outlet of the heat exchanger (E1) is not marked in the figure, and the heat exchanger is a conventional technology; the bottom of the Reline purification flash tank (F1) is provided with fresh and dry Reline deep eutectic solvent ( The outlet of freshly dried Reline deep eutectic solvent (S6) is connected to the absorbent feed port of the packed absorption tower (T1) via a pipeline. The bottom of the packed absorption tower (T1) is provided with an outlet of water-rich Reline deep eutectic solvent (S9). The outlet of water-rich Reline deep eutectic solvent (S9) is connected to the inlet of another channel of the heat exchanger (E1) via a pipeline. The outlet of another channel of the heat exchanger (E1) is connected to the feed port of the Reline recovery flash tower (F2) via a pipeline via a heater (H1). The bottom outlet of the Reline recovery flash tower (F2) is connected to the inlet of another channel of the heat exchanger (E1). The inlet is connected by a pipeline (circulating flash pipeline), which can realize the cyclic dehydration of the water-rich Reline deep eutectic solvent (S9). At the same time, the bottom discharge port of the Reline recovery flash tower (F2) is connected to the absorbent feed port of the packed absorption tower (T1) by a pipeline (this connection is not drawn in the figure) for recycling the Reline deep eutectic solvent. The upper part of the Reline recovery flash tower (F2) is provided with an outlet for recovering flash water vapor (S12), and the outlet for recovering flash water vapor (S12) is connected to the inlet of the third condenser (C3) for condensing the recovered flash water vapor into liquid water for discharge.
[0009] The packed absorption tower (T1) is provided with a wet gas (S7) inlet, which is located at the lower part of the packed absorption tower (T1); the upper part of the packed absorption tower (T1) is provided with a dry gas (S8) outlet, which is connected to the second condenser (C2).
[0010] The absorbent feed inlet of the packed absorption tower (T1) is located at the first theoretical plate of the packing (from top to bottom), the wet gas (S7) inlet is located at the bottom of the tower, and the theoretical pedal number of the packed absorption tower (T1) is 5-15, which is designed according to needs.
[0011] The Reline purification flash tank (F1) and the Reline recovery flash tower (F2) are provided with an atmospheric pipeline (S10) as required.
[0012] In the present invention, when the pipeline connection contains liquid, gravity drive or pump drive can be adopted, which can be selected according to the needs; valves can also be designed and installed according to the needs when the pipeline is connected. The pipeline between the Reline recovery flash tower (F2) and the heat exchanger (E1) is provided with a valve, and the pipeline (circulation flash pipeline) between the Reline recovery flash tower (F2) and the packed absorption tower (T1) is provided with a valve.
[0013] The process of drying air and air separation gas using the above device mainly includes the following steps:
[0014] First, choline chloride (S1) and urea (S2) powders are added to a synthesis reaction tank (B1), and stirred and heated at 80°C and 101.325 kpa for 8 hours. After the reaction is completed, the fresh Reline deep eutectic solvent material (S3) is transported to a flash tank (F1), and flashed at low pressure (50 kpa and below) and high temperature (100°C and above) for 12 hours to ensure that the water content is completely removed and purified and dried; the fresh and dried Reline deep eutectic solvent (S6) enters the tower from the first theoretical plate (from top to bottom) of the packed absorption tower (T1), and the moisture enters the tower from the bottom of the tower. The gas and liquid are in countercurrent contact in the packing. After mass transfer is completed, the dry gas (S8) is extracted from the top of the tower, and the water-rich Reline deep eutectic solvent (S9) after water absorption is extracted from the bottom of the tower;
[0015] The water-rich Reline deep eutectic solvent (S9) is recovered. Specifically, the water-rich Reline deep eutectic solvent (S9) drawn out from the bottom of the packed absorption tower (T1) is heat exchanged in the heat exchanger (E1) and then heated by the heater (H1) before entering the recovery flash tank (F2). Since Reline is almost non-volatile, it can generally be separated from water vapor by a single flash recovery operation in the flash tank. If the water absorption amount is relatively large, it can be recycled by flash separation and recovery. The Reline deep eutectic solvent recovered by flash separation in the recovery flash tank (F2) enters the packed absorption tower (T1) again after heat recovery through a circulating pipeline. According to the present invention, after multiple cycles and uses between the packed absorption tower (T1) and the recovery flash tank (F2), the performance of Reline may be reduced or the quality may be lost. Therefore, the quality of Reline can be supplemented accordingly.
[0016] A preferred embodiment of the present invention is characterized in that the choline chloride and urea in the reaction tank (B1) are mixed in a molar ratio of 1:2.
[0017] In a preferred embodiment designed by the present invention, according to the physicochemical properties of Reline, the operating pressure of the packed absorption tower (T1) is 1-5atm, the operating temperature is 5-25°C, preferably 15°C, the number of theoretical plates (N) is 5-15, preferably 10, the feeding position of moisture in the packed absorption tower (T1) is the Nth plate, N is the bottom plate; the feeding position of Reline is the first plate at the top.
[0018] According to another preferred embodiment of the present invention, it is characterized in that the operating pressure of the Reline recovery flash tank (F2) is 0.3-0.5 atm, and the operating temperature is 120-150°C.
[0019] According to another preferred embodiment of the present invention, it is characterized in that the air and air separation gas can be any one of air, nitrogen and oxygen.
[0020] According to another preferred embodiment of the present invention, it is characterized in that the mass ratio of the total amount of the desiccant to the gas to be dried is 0.5:1 to 4:1.
[0021] According to another preferred embodiment of the present invention, it is characterized in that the water content of the dried gas is about 1%, and the water content of the gas after drying is less than 100 ppm.
[0022] [Beneficial Effects]
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] (1) The present invention has a simple principle, convenient operation, outstanding drying effect, and strong feasibility. Reline can greatly improve the drying effect under the premise that the raw material cost is comparable to that of ordinary organic.
[0025] (2) Reline has good biodegradability and low volatility. It will not evaporate again during its generation, use and transportation. Its synthesis process will not produce any by-products. The recycling process has low energy consumption and reduces greenhouse gas emissions. The entire process is extremely consistent with the principles of green chemistry.
Brief Description of the Drawings
[0026] Attached Figure 1 The process map for the designed Reline dry air and air separation gas;
[0027] In the figure, B1-synthesis tank with stirring; F1-purification flash tank; T1-packed absorption tower; F2-recovery flash tank, H1-heater, C1-first condenser, C2-second condenser, C3-third condenser; S1-choline chloride; S2-urea, S3-fresh Reline deep eutectic solvent, S4-flash steam, S5 condensed water, S6-fresh and dried Reline deep eutectic solvent, S9-water-enriched Reline deep eutectic solvent, S10-air pipeline, S11-circulation flash pipeline, S12-recovery flash water vapor. [Specific implementation method]
[0028] The following is further described in conjunction with the accompanying drawings, which does not limit the scope of the present invention. Without departing from the scope of the above-mentioned purpose, the modified embodiments are included in the technical scope of the present invention.
[0029] The following example: Choline chloride and urea react at 80°C and 101.325kpa for more than 8 hours to form a colorless and transparent Reline deep eutectic solvent liquid, which is then transported to a purification flash tank for purification, and flashed at a low pressure of 50kpa or less and a high temperature of 100°C or above for 12 hours. In order to ensure continuous operation, the number of equipment in this process can be increased according to actual needs.
[0030] Embodiment 1:
[0031] The structure and process diagram are as follows: Figure 1 As shown; the air drying process, air composition (oxygen 50wt%, nitrogen wt%, water 5wt%), feed temperature of 30℃, feed flow rate of 500kg / h, Reline as gas desiccant, mass flow rate of 500kg / h, packed absorption tower operating pressure of 1atm, packed absorption tower operating temperature of 15℃; Reline recovery flash tank flash temperature of 120℃, operating pressure of 0.1atm, packed absorption tower (T1) has 10 equivalent theoretical plates, wet air feed position is the 11th plate (tower bottom), Reline is fed from the 1st plate position of the equivalent theoretical plate. After multiple equilibrium stages of gas-liquid phase equilibrium, the water content of the dry gas produced from the top of the tower is 0.03ppm (mass fraction), and the water content in Reline is 1.8%.
[0032] Embodiment 2:
[0033] The structure and process diagram are as follows: Figure 1As shown; wherein the oxygen drying process, oxygen composition (oxygen 99wt%, water 1wt%), feed temperature is 25℃, feed flow rate is 200kg / h, Reline is used as gas desiccant, mass flow rate is 200kg / h, packed absorption tower operating pressure is 1atm, packed absorption tower operating temperature is 25℃; Reline recovery flash tank flash temperature is 120℃, operating pressure is 0.5atm, packed absorption tower (T1) has 10 equivalent theoretical plates, wet air feed position is the 11th plate, Reline is fed from the 1st plate position of the equivalent theoretical plate. After multiple equilibrium stages of gas-liquid phase equilibrium, the water content of the dry gas produced from the top of the tower is 0.09ppm (mass fraction), and the water content in Reline is 1.63%.
[0034] Embodiment 3:
[0035] The structure and process diagram are as follows: Figure 1 As shown; wherein the nitrogen drying process, the air composition (nitrogen 99wt%, water 1wt%), the feed temperature is 20℃, the feed flow rate is 300kg / h, Reline is used as a gas desiccant, the mass flow rate is 300kg / h, the operating pressure of the packed absorption tower is 1atm, and the operating temperature of the packed absorption tower is 30℃; the flash temperature of the Reline recovery flash tank is 120℃, the operating pressure is 0.5atm, the equivalent theoretical plate number of the packed absorption tower (T1) is 12, the feed position of the wet air is the 13th plate, and Reline is fed from the 1st plate position of the equivalent theoretical plate. After multiple equilibrium stages of gas-liquid phase equilibrium, the water content of the dry gas produced from the top of the tower is 0.03ppm, and the water content in Reline is 1.8%.
Claims
1. A full-line device for drying air and air separation gases using Reline deep eutectic solvent, characterized in that: The invention comprises a Reline synthesis reaction tank (B1), a Reline purification flash tank (F1), a packed absorption tower (T1), a Reline recovery flash tower (F2), a heat exchanger (E1), a heater (H1), a first condenser (C1), a second condenser (C2), and a third condenser (C3); the Reline synthesis reaction tank (B1) is provided with choline chloride (S1) and urea (S2) inlets, the bottom of the Reline synthesis reaction tank (B1) is provided with a fresh Reline deep eutectic solvent (S3) outlet, and fresh Reline The outlet of the Reline deep eutectic solvent (S3) is connected to the feed port of the Reline purification flash tank (F1) through a pipeline. The upper part of the Reline purification flash tank (F1) is provided with a flash steam (S4) outlet, and the flash steam (S4) outlet is connected to the first condenser (C1). The condensed water (S5) outlet corresponding to the first condenser is connected to the water inlet of the heat exchanger (E1) through a pipeline; the bottom of the Reline purification flash tank (F1) is provided with a freshly dried Reline deep eutectic solvent (S6) outlet, and the freshly dried Reline deep eutectic solvent The outlet of (S6) is connected to the absorbent feed port of the packed absorption tower (T1) via a pipeline. The bottom of the packed absorption tower (T1) is provided with an outlet of a water-rich Reline deep eutectic solvent (S9). The outlet of the water-rich Reline deep eutectic solvent (S9) is connected to the inlet of another channel of the heat exchanger (E1) via a pipeline. The outlet of another channel of the heat exchanger (E1) is connected to the feed port of the Reline recovery flash tower (F2) via a pipeline via a heater (H1). The bottom outlet of the Reline recovery flash tower (F2) is connected to the inlet of another channel of the heat exchanger (E1). The outlet of the Reline recovery flash tower (F2) is connected by a pipeline, which can realize the cyclic dehydration of the water-rich Reline deep eutectic solvent (S9). At the same time, the bottom discharge port of the Reline recovery flash tower (F2) is connected to the absorbent feed port of the packed absorption tower (T1) by a pipeline, which is used to recover the Reline deep eutectic solvent for reuse; the upper part of the Reline recovery flash tower (F2) is provided with an outlet for recovering flash vapor (S12), and the outlet of the recovery flash vapor (S12) is connected to the inlet of the third condenser (C3) for condensing the recovered flash vapor into liquid water for discharge; The packed absorption tower (T1) is provided with a wet gas (S7) inlet, which is located at the lower part of the packed absorption tower (T1); the upper part of the packed absorption tower (T1) is provided with a dry gas (S8) outlet, which is connected to the second condenser (C2).
2. A full-line device for drying air and air separation gas using Reline deep eutectic solvent according to claim 1, characterized in that: The theoretical number of plates N of the packed absorption tower (T1) is 5-15, preferably 10. The feeding position of moisture in the packed absorption tower (T1) is the Nth plate, where N is the bottom plate; the feeding position of Reline is the first plate at the top.
3. A full-line device for drying air and air separation gas using Reline deep eutectic solvent according to claim 1, characterized in that: The Reline purification flash tank (F1) and the Reline recovery flash tower (F2) are provided with an atmospheric pipeline (S10) as required.
4. A full-line device for drying air and air separation gas using Reline deep eutectic solvent according to claim 1, characterized in that: It is driven by gravity or pump; valves are designed and installed as needed when connecting pipelines.
5. A full-line device for drying air and air separation gas using Reline deep eutectic solvent according to claim 1, characterized in that: A valve is provided on the pipeline between the Reline recovery flash tower (F2) and the heat exchanger (E1), and a valve is provided on the pipeline between the Reline recovery flash tower (F2) and the packed absorption tower (T1).
6. A process for drying air and air separation gas using the device according to any one of claims 1 to 5, characterized in that: The main steps are as follows: First, choline chloride (S1) and urea (S2) powders are added to a synthesis reaction tank (B1), and stirred and heated at 80°C and 101.325 kpa for 8 hours. After the reaction is completed, the fresh Reline deep eutectic solvent material (S3) is transported to a flash tank (F1), and flashed at low pressure (50 kpa and below) and high temperature (100°C and above) for 12 hours to ensure that the water content is completely removed and purified and dried; the fresh and dried Reline deep eutectic solvent (S6) enters the tower from the first theoretical plate of the packed absorption tower (T1), and the moisture enters the tower from the bottom of the tower. The gas and liquid are in countercurrent contact in the packing. After mass transfer is completed, the dry gas (S8) is extracted from the top of the tower, and the water-rich Reline deep eutectic solvent (S9) after water absorption is extracted from the bottom of the tower; The water-rich Reline deep eutectic solvent (S9) is recovered. Specifically, the water-rich Reline deep eutectic solvent (S9) drawn out from the bottom of the packed absorption tower (T1) is heat exchanged in the heat exchanger (E1) and then heated by the heater (H1) before entering the recovery flash tank (F2). Since Reline is almost non-volatile, it can generally be separated from water vapor by a single flash recovery operation in the flash tank. If the amount of water absorbed is relatively large, a cyclic flash separation and recovery operation can be performed. The Reline deep eutectic solvent recovered by flash separation in the recovery flash tank (F2) enters the packed absorption tower (T1) again after heat recovery through a circulating pipeline.
7. The process according to claim 6, characterized in that The choline chloride and urea in the reaction tank (B1) are mixed in a molar ratio of 1:
2.
8. The process according to claim 6, characterized in that According to the physicochemical properties of Reline, the operating pressure of the packed absorption tower (T1) is 1-5 atm, and the operating temperature is 5-25°C, preferably 15°C; The operating pressure of the Reline recovery flash tank (F2) is 0.3-0.5 atm, and the operating temperature is 120-150°C.
9. The process according to claim 6, characterized in that The air and air separation gas can be any one of air, nitrogen and oxygen.
10. The process according to claim 6, characterized in that The water content of the dried gas is less than 100 ppm.