A method for preparing high softening point asphalt using ethylene tar as an auxiliary agent

Abstract

The present invention relates to a method for preparing high softening point asphalt using ethylene tar as an auxiliary agent. The method comprises the following steps: S1: using ethylene tar as an auxiliary agent and high temperature coal tar for mixed distillation, and extracting light components in each distillation section; and S2: subjecting the remaining heavy components after distillation to high temperature thermal polymerization to prepare high softening point asphalt, wherein the softening point of the high softening point asphalt is within the range of 100°C-110°C, the coking value is not less than 50%, the toluene insoluble content is within the range of 26%-32%, and the quinoline insoluble content is within the range of 6%-12%. The present invention uses ethylene tar as an auxiliary agent and high temperature coal tar as a stabilizer, and the two can be well soluble in each other, and the raw material properties can be improved mutually, so that the mixed material has the advantages of both ethylene tar and high temperature coal tar, reduces production costs, and improves economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of asphalt, and in particular relates to a method for preparing high-softening-point asphalt by using ethylene tar as an auxiliary agent. Background Art

[0002] Ethylene tar is a high-temperature condensation product of cracking raw materials during steam cracking. Its composition and output vary with different ethylene cracking raw materials and cracking conditions. The output is about 10%-15% of ethylene output. Ethylene tar contains a large amount of aromatic compounds such as indene and naphthalene, and is a high-quality chemical raw material. The development and utilization of ethylene tar will bring considerable economic benefits to enterprises. The comprehensive utilization of ethylene tar in my country started late, and the current use of ethylene tar in my country is mainly for fuel. Compared with the production of carbon black from ethylene cracking tar abroad, the economic utilization rate as a fuel is low, and it is also easy to produce black smoke and cause environmental pollution. In recent years, a large number of studies have been carried out in China on the composition characteristics of ethylene tar, with the aim of improving the utilization rate of ethylene tar. The research on mass production of chemicals using ethylene tar as raw material oil is imminent, which can not only improve economic benefits but also reduce pollution. At present, the use of ethylene tar as an auxiliary agent for auxiliary production is rarely reported, and most of them are produced as a single raw material. Therefore, broadening the comprehensive utilization of ethylene tar and realizing diversified utilization has good prospects and economic benefits. Summary of the invention

[0003] The present invention aims at the defects of the prior art such as low utilization and insufficiency of ethylene tar, and provides a method for comprehensive utilization of ethylene tar, which improves the comprehensive utilization value of ethylene tar raw materials. At the same time, the present invention solves the problems of low yield of high-purity industrial naphthalene, low coking value of high softening point asphalt, excessive generation of supersaturated steam in the distillation process, etc. caused by the defects of low naphthalene content, high raw material activity, and low carbon content of ethylene tar raw materials. In addition, the method can also improve the quality of high softening point asphalt products, reduce the content of metal elements in asphalt, and reduce the content of quinoline insolubles. The method has simple process, easy operation, low equipment demand, low investment, low energy consumption, low operating cost, and high comprehensive benefits.

[0004] To achieve the above purpose, the specific technical solution of the present invention is as follows:

[0005] A method for preparing high softening point asphalt using ethylene tar as an auxiliary agent, comprising the following steps:

[0006] S1: Using ethylene tar as an auxiliary agent and high-temperature coal tar for mixed distillation to extract light components in each distillation section; and

[0007] S2: The remaining heavy components after distillation are subjected to high-temperature thermal polymerization to prepare a high softening point asphalt, wherein the high softening point asphalt has a softening point within the range of 100°C-110°C, a coking value of not less than 50%, a toluene insoluble matter content within the range of 26%-32%, and a quinoline insoluble matter content within the range of 6%-12%.

[0008] In the present invention, ethylene tar refers to the product of high-temperature condensation of raw materials and products when cracking to produce ethylene, and its naphthalene content is ≥7%. When it is lower than this range, the yield of high-purity naphthalene crystallization will be too low, and the economy will be poor; the water content is not more than 4%. When the water content is higher than 4%, it will cause risks such as violent boiling and liquid splashing of the material during the distillation process, affecting the experimental operation and experimental results; the sulfur content should not be higher than 3%. When it is higher than this range, it will affect the quality of the high-purity naphthalene crystallization product and the economy will be poor.

[0009] In the present invention, the high-temperature coal tar refers to a by-product obtained by high-temperature (750°C-800°C) dry distillation of coal, the main components of which are aromatic hydrocarbons and organic compounds containing oxygen, nitrogen or sulfur, etc. The moisture content of the raw material should not be higher than 4%. When it is higher than this range, it will cause risks such as violent boiling and liquid splashing during the distillation process of the material, affecting the experimental operation and experimental results; the ash content should not be higher than 0.1%. When it is higher than this range, it will affect the quality of the modified coal tar product and the economy is not good; the naphthalene content should not be less than 10%. When it is lower than this range, it will cause the high-purity naphthalene crystallization yield to be too low, and the economy is not good. In a specific implementation, in step S1, ethylene tar and high-temperature coal tar are mixed and stirred in a constant temperature water bath, the stirring time should not be less than 15 minutes, and the stirring temperature should not be less than 70°C. Below this time range and temperature range, the two materials will be mixed unevenly, which will have an adverse effect on subsequent experiments.

[0010] In a specific implementation, in step S1, taking into account the use effect and economic factors, the blending ratio of ethylene tar to high-temperature coal tar is 1:2-1:3, preferably 1:2.0-1:2.5.

[0011] In a specific implementation, in step S1, ethylene tar is mixed with high-temperature coal tar and then distilled by atmospheric distillation.

[0012] In a specific embodiment, in step S1, the light components produced contain triphenyl fraction, phenol oil, naphthalene oil and wash oil with successively increasing boiling points, wherein the triphenyl fraction is produced at an initial distillation point of -180°C, the phenol oil is produced at 180°C-210°C, the naphthalene oil is produced at 210°C-230°C, and the wash oil is produced at 230°C-300°C.

[0013] In a specific embodiment, the high temperature thermal polymerization operating conditions in step S2 are as follows: polymerization temperature 360-380° C., reaction time 6-12 h, vacuum stripping time 1.5 h, and vacuum degree during vacuum stripping is 15 kPa.

[0014] Beneficial Effects

[0015] In the present invention, ethylene tar is used as an auxiliary agent, and the advantages of ethylene tar such as less impurities, low sulfur content and low quinoline insolubles are utilized to improve the high-temperature coal tar raw material, thereby improving the quality of the high-temperature coal tar separation product; high-temperature coal tar is used as a stabilizer, and the advantages of high-temperature coal tar such as more heavy components, high carbon content and stable properties are utilized to improve the ethylene tar raw material, change the ethylene tar distillation curve, reduce the amount of supersaturated steam of ethylene tar at a specific temperature, make the distillation process tend to be stable, and make the distillation separation more complete.

[0016] In summary, the present invention uses ethylene tar as an auxiliary agent and high-temperature coal tar as a stabilizer. The two can be well soluble in each other and improve the properties of the raw materials. The mixed material has the advantages of both ethylene tar and high-temperature coal tar, reducing production costs and improving economic benefits.

[0017] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

[0018] This disclosure document provides an overview of various implementations or examples of the technology described in this disclosure, and is not a comprehensive disclosure of the full scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of an atmospheric distillation apparatus for mixing auxiliary agent ethylene tar and stabilizer coal tar in this application.

[0020] Figure 2 This is a schematic diagram of the high-temperature thermal polymerization device for atmospheric distillation of heavy components in this application.

[0021] Description of reference numerals:

[0022] 1-three-necked round-bottom flask; 2-temperature sensor; 3-distillation column; 4-tower top condensation device; 5-reflux condensation device; 6-product cooling device.

[0023] 21-gas phase condensing device; 22-stepping stirring paddle; 23-reactor; 24-gas phase outlet pipeline; 25-stepping stirring paddle motor; 26-vacuum extraction pipeline; 27-vacuum tank; 28-vacuum gas phase condensing device.

[0024] Figure 1The apparatus for atmospheric distillation in the present application is shown as an example, and the qualified mixed material is placed in a three-necked round-bottom flask 1 assembled to the bottom of the distillation device. The three-necked round-bottom flask 1 has a built-in temperature sensor 2 for monitoring the temperature inside the round-bottom flask 1. The light components in the mixed material are extracted from the top of the tower after distillation by the distillation column 3, and are condensed by the top condensation device 4 and the reflux condensation device 5, and then collected in the product cooling device 6.

[0025] Figure 2 2 shows an example of a device for high temperature thermal polymerization in the present application. The remaining heavy components in the round bottom flask are subjected to thermal polymerization reaction in a reactor 23. The reactor 23 is equipped with a step-by-step stirring paddle 22 and a step-by-step stirring paddle motor 25 for mixing the materials in the reactor. In addition, the reactor 23 is also connected to the gas phase condensation device 21 through a gas phase outlet pipeline 24, and the reactor 23 is also connected to a vacuum tank 27 and a vacuum gas phase condensation device 28 in sequence through a vacuum extraction pipeline 26. DETAILED DESCRIPTION

[0026] The scheme of the present application is described in detail below through specific examples, however, these examples are only exemplary and are not intended to limit the scope of the present invention.

[0027] Determination method:

[0028] The indexes of the high softening point asphalt, the target product finally obtained by the present invention, refer to GB / T 2290-2012, and some indexes are changed on the basis of this standard.

[0029] The detection methods used for each sample in the present invention are as follows:

[0030] YB / T 5078-2010 Determination of naphthalene content in coal tar - Gas chromatography method

[0031] GB / T 2295-2008 Determination of ash content in coking solid products

[0032] GB / T 2292-2018 Determination of toluene insoluble matter content in coking products

[0033] GB / T 2293-2019 Test method for quinoline insoluble matter in coking pitch products

[0034] GB / T 2291-2016 Preparation method of coal tar laboratory samples

[0035] GB / T 8727-2008 Determination of coking value of coal tar pitch products

[0036] GB / T 24533-2019 Graphite-based negative electrode materials for lithium-ion batteries Appendix H-Determination of trace metal elements

[0037] The ethylene tar and high-temperature coal tar used in the following examples are all raw materials from the same batch, and their specific indicators are as follows:

[0038]

[0039] Examples 1-12

[0040] (1) The auxiliary agent ethylene tar and the stabilizer high-temperature coal tar were stirred and mixed in a 1000 ml beaker according to the weight ratio in Table 1. The stirring temperature was 75°C and the stirring time was 30 min. After that, the naphthalene content, sulfur content and metal element content of the mixed material were measured. The results are shown in Tables 2 and 3 below. The naphthalene content of the mixed material should not be less than 10%, the metal element K content should not be higher than 12 ppm, and the metal element Zn content should not be higher than 100 ppm.

[0041] (2) Place the mixture in a 1000ml round-bottom flask and assemble the round-bottom flask to the bottom of the glass distillation device. Set the heating temperature of the electromagnetic heating jacket to 320°C and the heating rate to 1°C / min, and start heating for atmospheric distillation. The light components in the mixture are extracted from the top of the tower and collected after condensation in the condenser. The remaining heavy components remain at the bottom of the round-bottom flask. When the bottom temperature of the round-bottom flask reaches a constant temperature of 320°C and no light components overflow from the top of the tower, stop heating.

[0042] (3) The remaining heavy components in the round-bottom flask were transferred to a high-pressure asphalt reactor for thermal polymerization at a heating rate of 1°C / min and a stirring rate of 60 r / min. The thermal polymerization conditions are shown in Table 1. After the reaction, the high softening point asphalt sample was taken out, and the softening point, coking value, toluene insoluble content, and quinoline insoluble content were measured respectively. The results are shown in Table 4. The softening point of the high softening point asphalt should be between 100°C and 110°C, the coking value should be no less than 50%, the toluene insoluble content should be between 26% and 32%, and the quinoline insoluble content should be between 6% and 12%.

[0043] Comparative Example 1

[0044] The auxiliary agent ethylene tar and the stabilizer high temperature coal tar were weighed in a weight ratio of 1:9 (total weight 550g, weight fluctuation not exceeding 5g), and the weighed auxiliary agent and stabilizer were placed in a 1000ml beaker and stirred and mixed. The stirring temperature was 75°C and the stirring time was 30min. The naphthalene content, sulfur content and metal elements of the mixed material were determined, and the results are shown in Tables 2 and 3 below.

[0045] Comparative Example 2

[0046] The auxiliary agent ethylene tar and the stabilizer high temperature coal tar were weighed in a weight ratio of 1:4 (total weight 550g, weight fluctuation not exceeding 5g), and the weighed auxiliary agent and stabilizer were placed in a 1000ml beaker and stirred and mixed. The stirring temperature was 75°C and the stirring time was 30min. The naphthalene content, sulfur content and metal elements of the mixed material were determined, and the results are shown in Tables 2 and 3 below.

[0047] Comparative Example 3

[0048] The auxiliary agent ethylene tar and the stabilizer high temperature coal tar were weighed in a weight ratio of 2:3 (total weight 550g, weight fluctuation not exceeding 5g), and the weighed auxiliary agent and stabilizer were placed in a 1000ml beaker and stirred and mixed. The stirring temperature was 75°C and the stirring time was 30min. The naphthalene content, sulfur content and metal elements of the mixed material were determined, and the results are shown in Tables 2 and 3 below.

[0049] Comparative Example 4

[0050] The high softening point asphalt was prepared in the same manner as in Example 1, except that the auxiliary agent ethylene tar and the stabilizer high temperature coal tar were mixed in a weight ratio of 1:2.3, and in the thermal polymerization reaction, the reaction conditions were: the kettle temperature was 390°C, the reaction time was 10 hours, the vacuum stripping time was 3 hours, and the vacuum degree during the vacuum stripping was 18 kPa. The softening point, coking value, toluene insoluble content, and quinoline insoluble content of the high softening point asphalt sample are shown in Table 4 below.

[0051] Table 1 Product preparation parameters

[0052]

[0053] Table 2 Component analysis of mixed materials at different blending ratios

[0054]

[0055] Table 3 Metal element content of mixed materials at different blending ratios

[0056]

[0057] Table 4 Softening point, coking value, toluene insoluble matter and quinoline insoluble matter of high softening point asphalt

[0058]

[0059] The previous blending experiment finally concluded that the maximum acceptable blending ratio of ethylene tar additive is 3:7. In subsequent studies, it was concluded that the increase in reaction temperature, reaction time, and vacuum in the reactor will lead to an increase in the coking value, softening point, and toluene insoluble content of the asphalt product. Higher reaction temperatures give asphalt molecules a larger average kinetic energy, increase the frequency of effective collisions of molecules per unit time, and help small molecules to merge and combine into medium and large molecules. Since the coking value of asphalt is closely related to the volatile content and the content of macromolecular components, and the softening point is also related to the molecular weight of each substance inside the asphalt, the increase in reaction temperature will increase the coking value, toluene insoluble content, and softening point of the product. Longer reaction time can continue the above process, and long-term stripping can entrain more light components in the asphalt out of the reaction system, relatively increase the content of medium and high components inside the asphalt and accelerate the formation of secondary QI, resulting in an increase in the coking value, toluene insoluble content, quinoline insoluble content, and softening point of the asphalt. It was finally determined that the mixed raw material made of ethylene tar and coal tar in a blending ratio of 1:20-1:2.5, after separation by atmospheric distillation, the heavy component can be produced under the conditions of a heating rate of 1°C / min, a reaction temperature of 360-380°C, a constant temperature reaction time of 6-12h, a vacuum stripping of 1.5h, and a reactor vacuum of 15kPa, to produce a sample that meets the current asphalt product index requirements. In addition, with the formulation of ethylene tar, the content of some metal elements in the asphalt product has been reduced to a certain extent.

Claims

1. A method for preparing high softening point asphalt using ethylene tar as an auxiliary agent, comprising the following steps: S1: Using ethylene tar as an auxiliary agent and high-temperature coal tar for mixed distillation to extract light components in each distillation section, wherein the blending ratio of ethylene tar to high-temperature coal tar is 1:2-1:3; S2: subjecting the remaining heavy components after distillation to high-temperature thermal polymerization to prepare a high-softening point asphalt, wherein the high-softening point asphalt has a softening point in the range of 100°C-110°C, a coking value of not less than 50%, a toluene insoluble content in the range of 26%-32%, and a quinoline insoluble content in the range of 6%-12%. The high temperature thermal polymerization operating conditions are as follows: polymerization temperature 360-380°C, reaction time 6-12 h, vacuum stripping time 1.5 h, and vacuum degree during vacuum stripping is 15 kPa.

2. The method according to claim 1, wherein: In step S1, the blending ratio of ethylene tar to high-temperature coal tar is 1:2.0-1:2.

5.

3. The method according to claim 1, wherein: In step S1, ethylene tar is mixed with high-temperature coal tar and then distilled by atmospheric distillation.

4. The method according to claim 1, wherein: In step S1, the light components produced include triphenyl fraction, phenol oil, naphthalene oil and wash oil with successively increasing boiling points, wherein the triphenyl fraction is produced at an initial distillation point of -180°C, the phenol oil is produced at 180°C-210°C, the naphthalene oil is produced at 210°C-230°C, and the wash oil is produced at 230°C-300°C.

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