Efficient screening method of tar and wash oil composite solvent for recovering crude benzene in coke oven gas

Abstract

The invention discloses an efficient screening method of a tar and wash oil composite solvent for recovering crude benzene in coke oven gas, which comprises the following steps: by simulating the saturated vapor pressure of different solvents under the same condition, selecting various functional group organic solvents of which the saturated vapor pressure is lower than that of a wash oil solvent to perform low-volatility compound component preliminary screening; s2, calculating the binding energy of the components obtained through primary screening in the step S1, and screening out high-selectivity compound components; on the basis of S2, screening out a compound component with high dissolvability to benzene hydrocarbon to obtain an organic solvent; screening out a low-consumption and high-efficiency organic solvent suitable for absorbing the benzene hydrocarbon aiming at the S3; s5, screening out a tar washing oil composite solvent formula with strong benzene hydrocarbon absorption capacity, low loss and good cycle stability; the screening period of the tar and wash oil composite solvent can be greatly shortened, the research and development cost is effectively controlled, and the method has important application value in the field of coke oven gas crude benzene recovery.

Description

Technical Field

[0001] This invention relates to the field of coal chemical industry, and in particular to a method for efficient screening of tar wash oil composite solvents for recovering crude benzene from coke oven gas. Background Technology

[0002] Coke oven gas, as a complex chemical raw material, contains abundant organic compounds, among which benzene hydrocarbons are one of the most industrially valuable components. Existing benzene hydrocarbon recovery technologies include wash oil absorption, condensation, and adsorption. Among these, wash oil absorption is widely used in industry due to its low operating cost, simple equipment, and suitability for treating high-concentration benzene-containing waste gas. However, the absorption process suffers from problems such as insufficient absorption efficiency, high wash oil volatilization loss, and high viscosity of the wash oil solvent. Given the mature and low-cost nature of the wash oil process, adding compound components to the wash oil solvent to improve absorption efficiency and reduce wash oil loss is a simple and reliable method.

[0003] Currently, in the process of screening compound solvents, due to the large variety of solvents and their significant differences in properties, directly screening suitable solvents through experiments is time-consuming and costly. Therefore, breaking through the efficiency bottleneck of traditional screening methods and screening out low-consumption and high-efficiency tar washing oil compound solvents is an urgent task. Summary of the Invention

[0004] This invention overcomes the shortcomings of existing screening methods, such as high blindness and long screening cycle, and provides a low-consumption and high-efficiency screening method for recovering crude benzene from coke oven gas using a composite solvent of tar washing oil.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A screening method for a low-consumption and high-efficiency tar washing oil composite solvent for recovering benzene hydrocarbons from coke oven gas includes the following steps:

[0007] S1: Screening of Low-Volatile Components. Components with lower saturated vapor pressures than the tar wash oil were screened based on solvent volatility. Aspen Plus software was used to simulate the saturated vapor pressures of various selected solvents at a specific temperature. Organic solvents with lower saturated vapor pressures than the wash oil solvents were selected for initial screening of components. The selected solvents also possessed physicochemical properties such as high boiling point (≥200 ℃), high flash point (>60 ℃), low viscosity (≤15 mPa·s at 30 ℃), high thermal and chemical stability, low corrosiveness, and low toxicity.

[0008] S2: High-efficiency composite component screening. High-efficiency composite component screening involves using quantum computational chemistry software to select organic solvents with high selectivity and high solubility for benzene hydrocarbons from the composite components chosen in S1. Based on density functional theory, molecular structure optimization and frequency analysis are performed using the quantum computational chemistry SMD solvation model for both benzene hydrocarbons and the initially selected composite components, and their binding energies (ΔE) are calculated. bind The size of the benzene group was determined; the binding energy was used to evaluate the selectivity of the compound components for benzene groups, and the compound components with high selectivity for benzene groups were screened. Then, quantum computing chemistry software was used to calculate the solvation free energy of benzene groups in the highly selective compound components at the same temperature. The solvation free energy (ΔG) was then used to determine the solvation free energy. sol The Henry coefficient was further calculated and used to evaluate the solubility of the compound components in benzene hydrocarbons, and organic solvents with high solubility in benzene hydrocarbons were screened.

[0009] S3: Final selection of tar wash oil composite solvent: The organic solvents screened in S2 were examined for their actual absorption capacity for benzene hydrocarbons using dynamic absorption experiments. A low-consumption and high-efficiency organic solvent suitable for benzene hydrocarbon absorption was selected and added to the tar wash oil in a certain proportion. The final selection of the tar wash oil composite solvent with strong absorption capacity, low loss and good cycle stability for benzene hydrocarbons was made using dynamic absorption and desorption experiments.

[0010] In a preferred embodiment of the present invention, the compound components include, but are not limited to, dibutyl phthalate, sulfolane, tetraethylene glycol dimethyl ether, triethylene glycol butyl ether, dibutyl adipate, etc.

[0011] In a preferred embodiment of the present invention, the solvation free energy of benzene hydrocarbons in a solvent is calculated using the SMD solvation model in quantum computing chemistry software, and the Henry's coefficient is derived from the solvation free energy to measure the solubility of benzene hydrocarbons.

[0012] The density of the solvent is measured using a densitometer at the same temperature;

[0013] The static absorption experiment included measuring the partition coefficient K using the static headspace gas chromatography method. Five 65 ml glass bottles were taken, and 9–10 g of pure solvent and 3–5 mg of benzene hydrocarbon liquid were added to each. The mixture was thoroughly stirred to ensure homogeneity. The bottles were sealed with PTFE gasket caps and allowed to stand at 30 °C for 48 h to reach gas-liquid equilibrium. Then, the gaseous concentration of benzene in the headspace gas was measured using a gas chromatograph, and the concentration of benzene hydrocarbons in the liquid phase was calculated based on the law of conservation of mass, thus determining the K value. The calculation method is given in Formula 1.

[0014] The Henry's coefficient H is derived from the K value, and its magnitude is used to evaluate the solvent's absorption capacity for benzene hydrocarbons. The calculation method is shown in Formula 2.

[0015] The solvation free energy, density, solvent molecular weight, and Henry's law coefficient were correlated. The results are shown in Equations 3 and 4.

[0016] In a preferred embodiment of the present invention, based on density functional theory, benzene hydrocarbon molecules and organic solvents are selected and molecular structure optimization and frequency analysis are performed using quantum computing chemistry software to calculate the binding energy, which is used to measure the selectivity of the solvent for benzene hydrocarbons.

[0017] In a preferred embodiment of the present invention, the dynamic absorption experiment includes simulating the generation of benzene hydrocarbon gas by mixing air flow using a micro-injection pump, and contacting the absorbent and benzene hydrocarbon gas countercurrently in a packed tower, wherein the benzene hydrocarbon gas enters the packed tower from the bottom and the absorbent flows into the packed tower from the top.

[0018] In a preferred embodiment of the present invention, the results are obtained by measuring the concentrations of benzene group hydrocarbons in the inlet and outlet exhaust gases using gas chromatography.

[0019] In a preferred embodiment of the present invention, the packing of the packed tower is θ-ring packing with a height of 70 cm, the temperature inside the tower is 30°C, and the pressure inside the tower is 1 bar.

[0020] In a preferred embodiment of the present invention, the final absorbent is selected from benzene-containing hydrocarbon gas at a temperature of 30 °C, and the concentration of benzene-containing hydrocarbon gas is approximately 10,000 mg / m³. 3 The flow rate of benzene group hydrocarbons in the coal gas is 4 L / min, and the liquid-to-gas ratio is 3 L / m³. 3 .

[0021] In a preferred embodiment of the present invention, the absorbent is desorbed using a rotary evaporator at a temperature of 95 °C, a pressure of 10 kPa, and a desorption time of 48 h. The desorbed lean solution is then subjected to a dynamic absorption experiment to evaluate its absorption-desorption cycle performance. The number of cycles is 9.

[0022] In a preferred embodiment of the present invention, the absorbent is used for the recovery of benzene hydrocarbons from coke oven gas in coal chemical industry.

[0023] Formula 1:

[0024] Among them, C L and C G These represent the concentrations of benzene hydrocarbons in the liquid and gas phases, respectively, both in mg / m³. 3 .

[0025] Formula 2:

[0026] Where H is the Henry's law constant, kPa; K is the partition coefficient, dimensionless; R is the ideal gas constant, with a value of 8.314 J / (mol·K); T is the temperature, K; ρ is the density of the solvent component, kg / m³; and M is the molecular weight of the solvent, kg / mol.

[0027] Formula 3:

[0028] Where H is the Henry's law constant (kPa); R is the ideal gas constant (8.314 J / (mol·K); T is the temperature (K); ρ is the density of the solvent component (kg / m³); M is the molecular weight of the solvent (kg / mol); ΔG sol The value is the solvation free energy, in kJ / mol.

[0029] It can be made that: Then we have formula 4:

[0030] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0031] (1) This invention provides a method for screening tar wash oil compound solvents for recovering crude benzene from coke oven gas. Using quantum chemical calculations, a correlation model is established by setting up the solvation free energy in the quantum domain and fitting it with the solvent's density, molecular weight, and Henry's law constant to screen for highly efficient benzene absorbents. This method achieves accurate prediction of highly efficient absorbents. Compared to traditional experimental methods for screening compound solvents, this significantly shortens the absorbent screening cycle and effectively reduces experimental costs, demonstrating significant application value in the field of crude benzene recovery from coke oven gas.

[0032] (2) The tar wash oil compound solvent provided by the present invention has a significant improvement in the recovery of benzene hydrocarbons compared with traditional wash oil solvents. Since the components of wash oil solvent are mainly volatile aromatic compounds, long-term use will lead to a large loss rate of solvent volatility. Adding absorbents with low volatility, which are selected through gradual screening, helps to reduce the loss of solvent during use. A new solvent system with both high absorption performance and low volatility characteristics is constructed to achieve the purpose of energy saving and efficiency improvement.

[0033] (3) This invention combines quantum computational chemistry theory with absorption experiments to achieve optimized selection of absorbents. In both theoretical research and practical application, it ensures that the screening process has a solid and reliable scientific basis, and also provides precise feedback on the accuracy of the screening through experiments, thus selecting more efficient compound absorbents for practical applications and providing more targeted and practical solutions for related fields. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the absorption device of the present invention;

[0036] Figure 2 The absorption efficiency spectrum of benzene absorption by the tar wash oil compound solvent absorption and desorption cycle selected by this invention has the best absorption effect.

[0037] In the diagram, 1 is a nitrogen cylinder; 2 is a rotor flow meter; 5 is a gas generator; 6 is a buffer bottle; 7 is a gas phase sampling port; 9 is a packed absorption tower; 10 is a metering pump; 11 is a lean solution storage tank; and 12 is a rich solution absorption tank. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0040] Example 1

[0041] This invention provides a highly efficient screening method for a composite solvent of tar wash oil used to recover crude benzene from coke oven gas:

[0042] The first step was to screen low-consumption compound components. Based on the volatility of the solvents, the saturated vapor pressure and viscosity of various selected solvents at 30 °C were simulated using Aspen Plus software. Compound components with lower saturated vapor pressure and relatively lower viscosity than tar wash oil were screened, and the results are shown in Table 1.

[0043] Example 2

[0044] This invention provides a highly efficient screening method for a composite solvent of tar wash oil used to recover crude benzene from coke oven gas:

[0045] Screening of high-efficiency compound components. Targeting benzene, the most abundant component in crude benzene, the binding energy between benzene and the solvents after initial screening was calculated. A higher absolute value of the binding energy indicates a stronger binding force between the solvent and benzene. The calculation results show that dibutyl phthalate is the organic solvent with the highest binding force to benzene. Four other organic solvents with relatively high binding forces to benzene include propylene carbonate, sulfolane, dibutyl adipate, dioctyl adipate, and tetraethylene glycol butyl ether, as shown in Table 2.

[0046] Example 3

[0047] This invention provides a highly efficient screening method for a composite solvent of tar wash oil used to recover crude benzene from coke oven gas:

[0048] Screening of high-efficiency compound components. Benzene, the most abundant component in crude benzene, was still the target. The solvation free energy between benzene molecules and the initially screened absorbents was calculated to further screen absorbents. A larger absolute value of the solvation free energy indicates a stronger interaction between benzene molecules and solvent molecules, meaning the absorbent has a better solubility for benzene. The calculation results show that sulfolane has the highest organic solvent solubility for benzene. The other four organic solvents with high benzene solubility include propylene acetate, dibutyl phthalate, tetraethylene glycol dimethyl ether, and dioctyl adipate, as shown in Table 3.

[0049] Example 4

[0050] Targeting benzene, the absorbents with the best benzene absorption effect were selected from dibutyl phthalate, dibutyl adipate, dioctyl adipate, tetraethylene glycol dimethyl ether, propylene carbonate, sulfolane, and tetraethylene glycol butyl ether. A benzene waste gas concentration of 10000 mg / m³ was simulated using a micro-injection pump mixed with nitrogen. Absorption experiments were conducted on each solvent under the following conditions: gas flow rate of 4 L / min, liquid-to-gas ratio of 3 L / m³, temperature of 30 ℃, pressure of atm, and a 70 cm packed absorption column. The absorption efficiencies were 95.9%, 95.5%, 94.3%, 96.4%, 93.1%, 94.3%, and 94.6%, respectively.

[0051] Example 5

[0052] Targeting benzene, tetraethylene glycol dimethyl ether (TEGDME), which exhibits the highest benzene absorption efficiency, was blended with a wash oil solvent after screening. The selected TEGDME blending ratios were 5%, 10%, 15%, 20%, 25%, 30%, and 35%. The optimal blending ratio was selected by comparing the benzene absorption efficiency at different ratios. After dynamic absorption experiments, the absorption efficiency of the original wash oil solvent was 93.2%, while the absorption efficiencies after blending with the blended solvents were 93.4%, 94.2%, 95.1%, 95.6%, 96.1%, 96.3%, and 96.5%, respectively. The absorption efficiency of all novel blended solvents was higher than that of the wash oil solvent. With the increase of the TEGDME blending components, the benzene absorption efficiency of the blended wash oil solvent tended to level off after an initial increase. The increase was from 93.4% to 96.1% when the ratio increased from 5% to 25%, and the increase slowed down after 25%. Weighing the efficiency and cost of adding the absorbent, the optimal compound ratio was determined to be 25%, corresponding to an absorption efficiency of 96.1%.

[0053] Following dynamic absorption experiments, desorption experiments were conducted on the tetraethylene glycol dimethyl ether (25%)-wash oil composite solvent, which exhibited the highest benzene absorption efficiency. Desorption of the composite solvent was performed using a rotary evaporator under the following conditions: temperature 95 ℃, pressure 10 kPa, and desorption time 48 h. The desorbed lean solution was then subjected to repeated dynamic experiments to verify the recyclability of the absorbent through continuous absorption and desorption experiments. After 9 cycles, the tetraethylene glycol dimethyl ether (25%)-wash oil composite solvent still maintained a 94.5% absorption rate for benzene, confirming its excellent absorption and desorption cycle performance.

[0054] Table 1. Saturated vapor pressure and viscosity of various solvents

[0055] solvent Saturated vapor pressure / Pa μ / mPa·s Dibutyl phthalate 0.00612 13.4 propylene carbonate 4.4615 2.3 Sulfolane 0.8682 9.9 Dibutyl adipic acid 0.052 4.4 Dioctyl adipate 0.02 9.5 Tetraethylene glycol dimethyl ether 0.4748 2.9 Diethylene glycol butyl ether 4.5377 4.4 Triethylene glycol butyl ether 0.4632 8.3 Tetraethylene glycol butyl ether 0.0305 10.5 Triethylene glycol monomethyl ether 0.476 5.4 Tetraethylene glycol monomethyl ether 0.082 8.5 Phenylacetyl alcohol 4.5125 9.0

[0056] Table 2. Binding energies between various solvents and benzene molecules

[0057] solvent Molecular formula <![CDATA[ΔE bind / kJ mol -1 ]]> Dibutyl phthalate <![CDATA[C 16 H 22 O4]]> -32.82 propylene carbonate <![CDATA[C4H6O3]]> -31.77 Sulfolane <![CDATA[C4H8O2S]]> -30.89 Dibutyl adipic acid <![CDATA[C6H 10 O3]]> -27.54 Dioctyl adipate <![CDATA[C 22 H 42 O4]]> -28.13 Tetraethylene glycol dimethyl ether <![CDATA[C 10 H 22 O5]]> -22.27 Diethylene glycol butyl ether <![CDATA[C8H 18 O3]]> -21.84 Triethylene glycol butyl ether <![CDATA[C 10 H 22 O4]]> -22.14 Tetraethylene glycol butyl ether <![CDATA[C 12 H 26 O5]]> -22.75 Triethylene glycol monomethyl ether <![CDATA[C7H 16 O4]]> -21.97 Tetraethylene glycol monomethyl ether <![CDATA[C9H 20 O5]]> -22.32 Phenylacetyl alcohol <![CDATA[C8H 10 O]]> -21.78

[0058] Table 3. Solvation Free Energy between Various Solvent Molecules and Benzene Molecules

[0059] solvent H / kPa <![CDATA[ΔG sol / kJ mol -1 ]]> Dibutyl phthalate 12.60 -16.68 propylene carbonate 22.92 -18.06 Sulfolane 13.08 -19.18 Dibutyl adipic acid 16.68 -15.97 Dioctyl adipate 14.65 -16.39 Tetraethylene glycol dimethyl ether 14.16 -16.87 Diethylene glycol butyl ether 38.52 -15.00 Triethylene glycol butyl ether 18.12 -16.37 Tetraethylene glycol butyl ether 16.87 -16.03 Triethylene glycol monomethyl ether 45.48 -14.78 Tetraethylene glycol monomethyl ether 39.16 -15.89 Phenylacetyl alcohol 85.32 -13.39

[0060] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A highly efficient screening method for a composite solvent of tar wash oil used to recover crude benzene from coke oven gas, characterized in that, Package the following steps: S1: By simulating the saturated vapor pressure of different types of solvents under the same conditions, we select various functional group organic solvents with lower saturated vapor pressure than wash oil solvents for the initial screening of low-volatility compound components. S2: The binding energy of the components obtained from the initial screening in S1 is calculated based on density functional theory. The components with high selectivity for benzene hydrocarbons are screened out by the binding energy. S3: Based on S2, the solvation free energy of benzene hydrocarbons in highly selective compound components under the same conditions is calculated. The Henry coefficient is calculated from the solvation free energy. The compound components with high solubility for benzene hydrocarbons are screened out using the Henry coefficient, and organic solvents with high selectivity and high solubility for benzene hydrocarbons are obtained. S4: Dynamic absorption experiments were conducted on the organic solvents screened in S3 to examine their actual absorption capacity for benzene hydrocarbons, and a low-consumption and high-efficiency organic solvent suitable for the absorption of benzene hydrocarbons was screened out. S5: The organic solvents selected in S4 are compounded with tar wash oil at mass ratios of 5%, 10%, 15%, 20%, 25%, 30%, and 35%, respectively. Through dynamic absorption and desorption experiments, a tar wash oil composite solvent formulation with strong benzene hydrocarbon absorption capacity, low loss, and good cycle stability is selected.

2. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 1, characterized in that: In S1, different types of solvents simultaneously possess the properties of boiling point ≥200 ℃, flash point >60 ℃, and viscosity ≤15 mPa·s (30 ℃); the compound components include, but are not limited to, dibutyl phthalate, sulfolane, tetraethylene glycol dimethyl ether, triethylene glycol butyl ether, dibutyl adipate, etc.

3. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 1, characterized in that: In S2 and S3, the binding energy and free energy are calculated by using the M06-2X / 6-311G++(d,p) basis set in quantum computing chemistry software to perform structural optimization and frequency calculations to obtain the binding energy of the system; the solvation free energy of benzene hydrocarbons in solvent is calculated using the SMD solvation model, and the Henry's coefficient is derived from the solvation free energy to measure the solubility of benzene hydrocarbons.

4. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 1, characterized in that: In S2, the binding energy is used to evaluate the selectivity of the compound component to benzene hydrocarbons and to screen out compound components that are selective for benzene hydrocarbons.

5. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 1, characterized in that: In S2, density functional theory involves selecting benzene hydrocarbon molecules and organic solvents, using quantum computing chemistry software to perform molecular structure optimization and frequency analysis, and calculating the binding energy to measure the selectivity of the solvent for benzene hydrocarbons.

6. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 1, characterized in that: In S4 and S5, the dynamic absorption experiment includes simulating the generation of benzene hydrocarbon gas by mixing air flow using a micro-injection pump, contacting the absorbent and benzene hydrocarbon gas countercurrently in a packed tower, wherein the benzene hydrocarbon gas enters the packed tower from the bottom and the absorbent flows into the packed tower from the top, and the concentration of benzene hydrocarbon waste gas is detected.

7. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 6, characterized in that: The detection of benzene hydrocarbon waste gas concentration specifically involves measuring the inlet and outlet benzene hydrocarbon waste gas concentrations using gas chromatography to obtain the conclusions of a dynamic absorption experiment.

8. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 6, characterized in that: The temperature of the benzene hydrocarbon gas is 30 ℃, and the concentration of benzene hydrocarbon gas is approximately 10000 mg / m³. 3 The flow rate of benzene group hydrocarbons in the coal gas is 4 L / min, and the liquid-to-gas ratio is 3 L / m³. 3 .

9. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 1, characterized in that: In S6, the desorption experiment specifically involves using a rotary evaporator to desorb the absorbent at a temperature of 95 °C, a pressure of 10 kPa, and a desorption time of 48 h. The desorbed lean solution is then subjected to a dynamic absorption experiment to evaluate its absorption-desorption cycle performance, with a cycle count of 9 times.

10. The efficient screening method for tar wash oil composite solvent for recovering crude benzene from coke oven gas according to claim 9, characterized in that: The absorbent is used for the recovery of benzene hydrocarbons from coke oven gas in coal chemical industry; Formula 1: Among them, C L and C G These represent the concentrations of benzene hydrocarbons in the liquid and gas phases, respectively, both in mg / m³. 3； Formula 2: Where H is the Henry's law constant, kPa; K is the partition coefficient, dimensionless; R is the ideal gas constant, with a value of 8.314 J / (mol·K); T is the temperature, K; ρ is the density of the solvent component, kg / m³; and M is the molecular weight of the solvent, kg / mol. Formula 3: Where H is the Henry's law constant (kPa); R is the ideal gas constant (8.314 J / (mol·K); T is the temperature (K); ρ is the density of the solvent component (kg / m³); M is the molecular weight of the solvent (kg / mol); ΔG sol Let the solvation free energy be kJ / mol; we can let: Then we have formula 4: .

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