A composite absorbent based on diethylene glycol and paraffin oil

Abstract

The application discloses a composite absorbent based on diethylene glycol and paraffin oil, belongs to the field of chemical separation and gas purification, and comprises the following components in parts by weight: diethylene glycol 30-70 parts; paraffin oil 30-70 parts; and viscosity regulator 0-5 parts. The application solves the problem of narrow absorption spectrum of single solvent by synergistic solubilization of polar-nonpolar components, can simultaneously and efficiently absorb polar components such as water and alcohol and nonpolar hydrocarbons such as alkane and aromatic hydrocarbon, replaces traditional step-by-step absorption process, reduces equipment investment by 30-40%, simplifies process and is convenient to operate; the total absorption capacity of the composite absorbent is increased by 30-50% compared with single diethylene glycol or paraffin oil, the mass transfer rate is increased by 25-40%, the absorption efficiency of low-concentration gas phase components (such as VOCs concentration 500-1000 mg / m 3 ) is greater than or equal to 95%, and the composite absorbent is suitable for different concentration conditions.

Description

Technical Field

[0001] This invention belongs to the field of chemical separation and gas purification, specifically a composite absorbent based on diethylene glycol and paraffin oil. Background Technology

[0002] In the fields of chemical separation and gas purification, single absorbents suffer from problems such as narrow absorption spectrum, poor selectivity, high regeneration energy consumption, or insufficient system stability. Diethylene glycol, as a polar absorbent, has excellent absorption performance for polar components such as water and alcohols, but has weak solubility for non-polar hydrocarbon components such as alkanes and aromatics. Paraffin oil, as a non-polar absorbent, can efficiently dissolve non-polar hydrocarbons, but has almost no absorption effect on polar components.

[0003] Existing technologies often employ a single solvent for the stepwise absorption of polar and non-polar components, which suffers from drawbacks such as cumbersome processes, high equipment investment, and low absorption efficiency. A few composite absorbent systems exhibit problems such as unreasonable formulation ratios, lack of synergistic solubilization effects, and poor compatibility of physical properties like viscosity / boiling point, making it difficult to achieve integrated and efficient absorption of both polar and non-polar components. Furthermore, the synergistic mechanism of existing composite absorbents has not been clearly explored, making it impossible to optimize formulations based on actual operating conditions, thus limiting their industrial-scale application.

[0004] Furthermore, in practical applications of absorbents, the regeneration process of a single solvent is prone to problems such as high solvent loss and high desorption temperature. Existing composite systems have not solved this problem, resulting in high operating costs. Therefore, developing a composite absorbent that can achieve co-absorption of polar and non-polar components, has significant synergistic effects, good physical property compatibility, and excellent regeneration performance has become an urgent technical problem to be solved in the field of chemical separation. Summary of the Invention

[0005] This invention provides a composite absorbent based on diethylene glycol and paraffin oil to overcome the deficiencies in the prior art.

[0006] This invention is achieved through the following technical solution: A composite absorbent based on diethylene glycol and paraffin oil comprises the following substances in parts by weight: 30-70 parts diethylene glycol; 30-70 parts paraffin oil; and 0-5 parts viscosity modifier.

[0007] The composite absorbent based on diethylene glycol and paraffin oil, as described above, wherein the viscosity modifier is a polyether polyol.

[0008] The composite absorbent based on diethylene glycol and paraffin oil, as described above, has a polyether polyol with a molecular weight of 400-2000.

[0009] The preparation method of the composite absorbent based on diethylene glycol and paraffin oil as described above includes the following steps: Step 1: Weigh out diethylene glycol and paraffin oil according to the ratio. If a viscosity modifier is required, weigh it out according to the ratio as well. Step 2: Add diethylene glycol to the reaction vessel and add paraffin oil dropwise while stirring. If a viscosity modifier is also needed, add it directly. Step 3: After the paraffin oil is added, continue stirring until homogeneous to obtain the composite absorbent.

[0010] As described above, in a composite absorbent based on diethylene glycol and paraffin oil, the stirring speed in step two is 200-300 r / min, and the paraffin oil droplet acceleration rate is 5-10 mL / min.

[0011] In the composite absorbent based on diethylene glycol and paraffin oil described above, the stirring time in step four is 30-60 minutes.

[0012] The composite absorbent based on diethylene glycol and paraffin oil, as described above, is used as follows: the composite absorbent is introduced into a packed absorber or a plate absorber and comes into countercurrent contact with the gas phase to be treated for synergistic absorption.

[0013] The composite absorbent based on diethylene glycol and paraffin oil, as described above, has an absorption temperature of 20–60°C, an absorption pressure of 0.1–2.0 MPa, a gas-liquid ratio of (50–200):1, and a liquid-gas hourly space velocity of 1–5 h⁻¹ in the packed or plate absorber. -1 The temperature of the absorber bottom should not exceed 70℃.

[0014] As described above, a composite absorbent based on diethylene glycol and paraffin oil is used to separate the impurities absorbed by the composite absorbent after it becomes saturated by a regeneration method of depressurized heating desorption, thereby realizing the regeneration and recycling of the composite absorbent.

[0015] The composite absorbent based on diethylene glycol and paraffin oil described above has a desorption temperature of 80–120°C, a desorption pressure of 0.02–0.05 MPa, and a desorption time of 1–2 h in the regeneration method of depressurized heating desorption.

[0016] The advantages of this invention are: Achieving integrated and efficient absorption: Through the synergistic solubilization of polar and non-polar components, the problem of narrow absorption spectrum of single solvent is solved. It can simultaneously and efficiently absorb polar components such as water and alcohols and non-polar hydrocarbons such as alkanes and aromatics, replacing the traditional stepwise absorption process. Equipment investment is reduced by 30% to 40%, the process is simplified, and the operation is convenient. Significantly improved absorption performance: The total absorption capacity of the composite absorbent is 30%–50% higher than that of diethylene glycol or paraffin oil alone, and the mass transfer rate is increased by 25%–40%. This is particularly beneficial for low-concentration gaseous components (such as VOCs at concentrations of 500–1000 mg / m³). 3 Its absorption efficiency is ≥95%, making it suitable for various concentration conditions; It has good physical property compatibility and strong industrial applicability: by adjusting the ratio and selectively adding cosolvents, the viscosity of the system can be adjusted to 5-20 mPa·s, which is suitable for the mass transfer requirements of industrial packed towers or plate absorption towers. It can be prepared at room temperature and pressure without special equipment and is easy to mass-produce. Excellent regeneration performance and low operating cost: It adopts low-temperature desorption under reduced pressure, and the regeneration temperature is 20-30℃ lower than that of diethylene glycol alone. The single regeneration rate is ≥95%, the annual solvent loss rate is ≤3%, and the absorption capacity retention rate is ≥85% after 50 cycles, which significantly reduces regeneration energy consumption and solvent replenishment costs. Wide range of applications: It can be widely used in natural gas / oilfield gas dehydration and heavy hydrocarbon removal, refinery gas / cracking gas C3+ hydrocarbon recovery, petrochemical / coating / printing industry VOCs treatment, gas station / oil depot oil and gas recovery and other scenarios. The compounding ratio can be flexibly adjusted according to different working conditions, and it has strong adaptability. Environmentally friendly and highly safe: Diethylene glycol and paraffin oil are both low-toxicity, non-flammable, and high-boiling-point solvents. The system contains no volatile harmful components, there is no secondary pollution during use, and storage and transportation are safe. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] A composite absorbent based on diethylene glycol and paraffin oil comprises the following substances in parts by weight: 30-70 parts diethylene glycol; 30-70 parts paraffin oil; and 0-5 parts viscosity modifier. The ratio of diethylene glycol to paraffin oil can be adjusted according to the proportion of polar / non-polar components in the gas phase to be absorbed; a higher proportion of polar components increases the proportion of diethylene glycol, while a higher proportion of non-polar hydrocarbons increases the proportion of paraffin oil.

[0019] Preferably, the viscosity modifier described in this embodiment is a polyether polyol.

[0020] Preferably, the molecular weight of the polyether polyol described in this embodiment is 400-2000.

[0021] Preferably, the preparation method of this embodiment includes the following steps: Step 1: Weigh out diethylene glycol and paraffin oil according to the ratio. If a viscosity modifier is required, weigh it out according to the ratio as well. Step 2: Add diethylene glycol to the reaction vessel and add paraffin oil dropwise while stirring. If a viscosity modifier is also needed, add it directly. Step 3: After the paraffin oil is added, continue stirring until homogeneous to obtain the composite absorbent.

[0022] Preferably, in step two of this embodiment, the stirring speed is 200-300 r / min and the paraffin oil droplet acceleration rate is 5-10 mL / min.

[0023] Preferably, the stirring time in step four of this embodiment is 30 to 60 minutes.

[0024] Preferably, the operation of this embodiment is as follows: the composite absorbent is introduced into a packed absorber or a plate absorber and comes into countercurrent contact with the gas phase to be treated for synergistic absorption.

[0025] Preferably, the packing absorption tower or plate absorption tower described in this embodiment has an absorption temperature of 20–60°C, an absorption pressure of 0.1–2.0 MPa, a gas-liquid ratio of (50–200):1, and a liquid-gas hourly space velocity of 1–5 h⁻¹. -1 The temperature of the absorber bottom should not exceed 70℃.

[0026] Preferably, in this embodiment, after the composite absorbent is saturated, a regeneration method of depressurized heating desorption is used to separate the impurities absorbed by the composite absorbent, thereby realizing the regeneration and recycling of the composite absorbent.

[0027] Preferably, the desorption temperature of the regeneration method of depressurized heating desorption described in this embodiment is 80-120°C, the desorption pressure is 0.02-0.05 MPa, and the desorption time is 1-2 h. Example 1

[0028] Preparation: Add 50g of diethylene glycol to a stirring vessel and stir at 200r / min at room temperature. Add 50g of paraffin oil dropwise at 8mL / min. After the addition is complete, continue stirring for 40min to obtain a uniform and transparent composite absorbent with a system viscosity of 10.2mPa·s. Absorption test: The above-mentioned composite absorbent was introduced into the absorption tower and contacted countercurrently with the gas phase to be treated. The gas phase to be absorbed was water (polar, concentration 1000 mg / m³). 3 ) + n-Heptane (nonpolar, concentration 1000 mg / m³) 3 The system is a mixed system, and the absorption equipment is a small packed absorption tower with an absorption temperature of 35℃, an absorption pressure of 0.1MPa, and a gas-liquid ratio of 100:1. Absorption efficiency: water ≥98.5%, n-heptane ≥98.2%, total absorption capacity per unit mass of absorbent is 18.5 mg / g; Regeneration test: After absorption saturation, desorption was performed under reduced pressure and heating. The desorption temperature was 95℃, the desorption pressure was 0.03MPa, and the desorption time was 1.5h. The single regeneration rate was 96.8%. After 10 cycles, the absorption capacity retention rate was 95.3%, and after 50 cycles, the retention rate was 87.6%. Example 2

[0029] Preparation: Take 60g of diethylene glycol, add 40g of paraffin oil dropwise, stir for 30min, the viscosity of the system is 12.5mPa·s; Absorption test: The above-mentioned composite absorbent was introduced into the absorption tower and contacted countercurrently with the gas phase to be treated. The gas phase to be absorbed was water (polar, concentration 1000 mg / m³). 3 ) + n-Heptane (nonpolar, concentration 1000 mg / m³) 3 The system is a mixed system, and the absorption equipment is a small packed absorption tower with an absorption temperature of 35℃, an absorption pressure of 0.1MPa, and a gas-liquid ratio of 100:1. Absorption efficiency: water absorption efficiency ≥99.0%, n-heptane absorption efficiency ≥97.5%, total absorption capacity 17.2 mg / g; Regeneration test: single regeneration rate 96.2%, absorption capacity retention rate 86.8% after 50 cycles. Example 3

[0030] Preparation: Take 40g of diethylene glycol, add 60g of paraffin oil dropwise, stir for 50min, the viscosity of the system is 8.8mPa·s; Absorption test: The above-mentioned composite absorbent was introduced into the absorption tower and contacted countercurrently with the gas phase to be treated. The gas phase to be absorbed was water (polar, concentration 1000 mg / m³). 3 ) + n-Heptane (nonpolar, concentration 1000 mg / m³) 3 The system is a mixed system, and the absorption equipment is a small packed absorption tower with an absorption temperature of 35℃, an absorption pressure of 0.1MPa, and a gas-liquid ratio of 100:1. Absorption efficiency: water absorption efficiency ≥97.8%, n-heptane absorption efficiency ≥99.1%, total absorption capacity 17.8 mg / g; Regeneration test: After absorption saturation, desorption was performed by depressurization heating. The single regeneration rate was 97.0%, and the absorption capacity retention rate was 88.2% after 50 cycles. Example 4

[0031] Preparation: Take 50g of diethylene glycol, add 48g of paraffin oil, stir for 30min, then add 2g of polyether polyol with a molecular weight of 1000, and continue stirring for 20min. The viscosity of the system is 7.5mPa·s. Absorption test: The above-mentioned composite absorbent was introduced into the absorption tower and contacted countercurrently with the gas phase to be treated. The gas phase to be absorbed was water (polar, concentration 1000 mg / m³). 3 ) + n-Heptane (nonpolar, concentration 1000 mg / m³) 3 The system is a mixed system, and the absorption equipment is a small packed absorption tower with an absorption temperature of 35℃, an absorption pressure of 0.1MPa, and a gas-liquid ratio of 100:1. Absorption efficiency: water absorption efficiency ≥98.3%, n-heptane ≥98.0%, total absorption capacity 18.2 mg / g, mass transfer rate improved by 8.5% compared to Example 1; Regeneration test: single regeneration rate 96.5%, absorption capacity retention rate 87.2% after 50 cycles.

[0032] Comparative Example 1 Absorbent: pure diethylene glycol, viscosity 23.8 mPa·s; Absorption test: The above absorbent is introduced into the absorption tower and contacted countercurrently with the gas phase to be treated. The gas phase to be absorbed is water (polar, concentration 1000 mg / m³). 3 ) + n-Heptane (nonpolar, concentration 1000 mg / m³) 3 The system is a mixed system, and the absorption equipment is a small packed absorption tower with an absorption temperature of 35℃, an absorption pressure of 0.1MPa, and a gas-liquid ratio of 100:1. Absorption efficiency: 99.2% for water, only 35.6% for n-heptane, with a total absorption capacity of 7.8 mg / g; Regeneration test: Desorption temperature required is 120℃, single regeneration rate is 92.5%, and absorption capacity retention rate is 80.1% after 10 cycles.

[0033] Comparative Example 2 Absorbent: Pure paraffin oil, viscosity 6.5 mPa·s; Absorption test: The above absorbent is introduced into the absorption tower and contacted countercurrently with the gas phase to be treated. The gas phase to be absorbed is water (polar, concentration 1000 mg / m³). 3 ) + n-Heptane (nonpolar, concentration 1000 mg / m³) 3 The system is a mixed system, and the absorption equipment is a small packed absorption tower with an absorption temperature of 35℃, an absorption pressure of 0.1MPa, and a gas-liquid ratio of 100:1. Absorption efficiency: 99.0% for n-heptane, only 28.3% for water, with a total absorption capacity of 8.2 mg / g; Regeneration test: Single regeneration rate of 95.8%, but it is prone to stratification after absorbing water. After 5 cycles, the system becomes unstable and cannot be used anymore.

[0034] As can be seen from the above data, the diethylene glycol + paraffin oil composite absorbent of the present invention, regardless of the ratio, has a total absorption capacity and comprehensive absorption efficiency that are far higher than those of a single solvent, and has excellent regeneration and recycling performance; 50% diethylene glycol + 50% paraffin oil is the core preferred ratio, which has the best comprehensive absorption performance and regeneration performance; adding a small amount of viscosity modifier can further improve the mass transfer rate and adapt to high-requirement industrial conditions.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite absorbent based on diethylene glycol and paraffin oil, characterized in that: The substance comprises the following components in parts by weight: 30-70 parts diethylene glycol; 30-70 parts paraffin oil; and 0-5 parts viscosity modifier.

2. The composite absorbent based on diethylene glycol and paraffin oil according to claim 1, characterized in that: The viscosity modifier is a polyether polyol.

3. The composite absorbent based on diethylene glycol and paraffin oil according to claim 2, characterized in that: The molecular weight of the polyether polyol is 400-2000.

4. The composite absorbent based on diethylene glycol and paraffin oil according to claim 1, characterized in that: Its preparation method includes the following steps: Step 1: Weigh out diethylene glycol and paraffin oil according to the ratio. If a viscosity modifier is required, weigh it out according to the ratio as well. Step 2: Add diethylene glycol to the reaction vessel and add paraffin oil dropwise while stirring. If a viscosity modifier is also needed, add it directly. Step 3: After the paraffin oil is added, continue stirring until homogeneous to obtain the composite absorbent.

5. The composite absorbent based on diethylene glycol and paraffin oil according to claim 4, characterized in that: The stirring speed in step two is 200-300 r / min, and the paraffin oil droplet acceleration rate is 5-10 mL / min.

6. The composite absorbent based on diethylene glycol and paraffin oil according to claim 4, characterized in that: The stirring time in step four is 30 to 60 minutes.

7. The composite absorbent based on diethylene glycol and paraffin oil according to claim 1, characterized in that: Its operation is as follows: the composite absorbent is introduced into the packed absorption tower or plate absorption tower and comes into countercurrent contact with the gas phase to be treated for synergistic absorption.

8. The composite absorbent based on diethylene glycol and paraffin oil according to claim 7, characterized in that: The packed or plate absorber has an absorption temperature of 20–60℃, an absorption pressure of 0.1–2.0 MPa, a gas-liquid ratio of (50–200):1, and a liquid-gas hourly space velocity of 1–5 h⁻¹. -1 The temperature of the absorber bottom should not exceed 70℃.

9. The composite absorbent based on diethylene glycol and paraffin oil according to claim 1, characterized in that: After the composite absorbent becomes saturated, it is regenerated by depressurization and heating to separate the impurities absorbed by the composite absorbent, thereby realizing the regeneration and recycling of the composite absorbent.

10. The composite absorbent based on diethylene glycol and paraffin oil according to claim 1, characterized in that: The desorption temperature of the regeneration method using reduced pressure heating desorption is 80-120℃, the desorption pressure is 0.02-0.05MPa, and the desorption time is 1-2h.