Process for preparing impregnated asphalt by two-step method

Abstract

The invention relates to the technical field of petrochemical engineering, in particular to a process for preparing impregnated asphalt by a two-step method, which comprises the following steps: 1) putting petroleum resin into a reaction kettle, and carrying out self-boosting heating to carry out polymerization reaction; 2) discharging gas generated by polymerization reaction in the reaction kettle; 3) discharging the cooled material in the reaction kettle as a primary product; 4) mixing the primary product with a viscosity reducer, then putting the mixture into the reaction kettle again, and carrying out normal-pressure heating treatment; the obtained product is the impregnated asphalt. According to the invention, the contradiction between high carbon residue value and fluidity (viscosity) after heat treatment of the asphalt and the contradiction between the softening point and high carbon residue value after heat treatment of the asphalt are solved; the softening point of the prepared impregnated asphalt is 80-100 DEG C, the carbon residue value is greater than 46%, the viscosity at 200 DEG C is less than 0.4 Pa.s, and the QI is less than 0.1%; the production process is simple, the production cost is low, energy conservation and environmental protection are achieved, and product index parameters can be adjusted according to user requirements.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a two-step process for preparing impregnated asphalt. Background Art

[0002] Impregnation asphalt is a special asphalt material used to impregnate carbon products in the production process of carbon materials. It improves the density, strength and permeability resistance of the material by filling the pores, and plays a key role in densification in the impregnation process of high-power and ultra-high-power graphite electrodes. The quality standard of impregnation asphalt in China has not been clearly formulated, and it can only be judged by indicators that affect the performance of impregnation asphalt, which mainly include: QI (quinoline insoluble matter), softening point, residual carbon value, viscosity, etc. Among them, low QI content (QI < 0.5%) can avoid the accumulation of QI particles on the surface of the graphite electrode and reduce the resistance of the impregnant asphalt to penetrate into the interior; low softening point (usually 45-115°C) means that the viscosity of the impregnant asphalt is low, the fluidity is good, and it has a better impregnation effect; high residual carbon value (usually ≥ 27%) indicates that the impregnated asphalt can retain more coke residue when it is roasted again; low viscosity means that the fluidity and dispersibility of the asphalt are good, and it can better penetrate into the pores of the carbon material during the impregnation process, so that the graphite electrode can achieve a higher weight gain rate.

[0003] Impregnated asphalt mainly includes petroleum asphalt, coal asphalt and coal tar asphalt; among them, petroleum asphalt has low QI content, low residual carbon value, good fluidity and strong permeability, but it needs to be repeated many times during the impregnation and sintering process to reach the predetermined density, thus increasing the production cost; coal asphalt has a high softening point (usually ≥100°C), and even if it is refined in the early stage to make QI <1%, its QI content will increase a lot after high-temperature polymerization reaction; and coal tar asphalt contains a large number of polycyclic aromatic hydrocarbon structures that are carcinogenic and harmful to health, which does not meet environmental protection requirements.

[0004] With the development of electric furnaces towards large-scale and the continuous progress of material science, impregnation asphalt is developing towards low QI, high carbon residue and customization to meet high-end needs such as high-power electrodes and new energy materials. Therefore, it is necessary to develop a method that can polymerize petroleum-based asphalt and increase the carbon residue value without increasing the softening point, QI and viscosity. Summary of the invention

[0005] The present invention provides a two-step process for preparing impregnated asphalt, which solves the contradiction between high carbon residue value and fluidity (viscosity) after asphalt heat treatment, and the contradiction between softening point and high carbon residue value after asphalt heat treatment; the prepared impregnated asphalt has a softening point of 80-100°C, a carbon residue value of >46%, a viscosity of <0.4Pa·s at 200°C, and a QI of <0.1%; the production process is simple, the production cost is low, the energy saving and environmental protection are achieved, and the product index parameters can be adjusted according to user needs.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A two-step process for preparing impregnated asphalt comprises the following steps:

[0008] 1) Put the petroleum resin into the reactor, introduce argon protection, self-pressurize and heat to carry out polymerization reaction, and stop heating when the material reaches the set heating temperature;

[0009] 2) The gas generated by the polymerization reaction in the reactor is released from the top vent valve, and the gas enters the condenser through the buffer tank. The tail gas separated by the condenser enters the tail gas collection system, and the separated light oil enters the light oil collection tank; when the material temperature in the reactor drops to the set temperature, stop releasing the gas;

[0010] 3) Open the discharge valve at the bottom of the reactor to discharge the cooled material in the reactor as the preliminary product;

[0011] 4) The preliminary product is mixed with the viscosity reducer and then put into the reactor again for heating treatment at normal pressure; the weight ratio of the mixture is 100 parts of the preliminary product and 2-10 parts of the viscosity reducer; after the temperature of the mixed material in the reactor reaches the set heating temperature, it is stirred at a constant temperature for a period of time, and then the discharge valve at the bottom of the reactor is opened to discharge the material into the asphalt collection tank, and the obtained product is the impregnated asphalt.

[0012] In the step 1), the property indicators of the petroleum resin are: softening point 120-130° C., residual carbon value 30%-35%.

[0013] In the step 1), the set heating temperature of the material during the polymerization reaction is 370-385° C., and the vacuum degree is less than 1 MPa.

[0014] In the step 2), when the temperature of the material in the reactor drops to 290-310° C., the gas release is stopped.

[0015] In the step 4), the viscosity reducing agent is one or more of ethylene glycol, propylene glycol, butylene glycol, glycerol, diethylene glycol and triethylene glycol.

[0016] In the step 4), the set heating temperature of the mixture in the reaction kettle is 200-220° C., and the constant temperature stirring time is 10-60 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) Compared with the conventional impregnation asphalt production process, the contradiction between the high carbon residue value and fluidity (viscosity) after asphalt heat treatment, as well as the contradiction between the softening point and high carbon residue value after asphalt heat treatment is solved; the prepared impregnation asphalt has a softening point of 80-100°C, a carbon residue value of >46%, a viscosity of <0.4Pa·s at 200°C, and a QI of <0.1%; the product performance is improved;

[0019] 2) The raw materials are widely available, cheap and have low production costs:

[0020] 3) The production process is carried out under self-pressurization (pressure <1MPa) and normal pressure conditions, which is safe to operate, greatly reduces equipment investment and production energy consumption, is conducive to energy conservation and emission reduction, and has good environmental benefits;

[0021] 4) The operation is simple. By adjusting parameters such as the final reaction temperature, constant temperature time and viscosity reducer ratio, the softening point, residual carbon content and viscosity of the impregnated asphalt can be adjusted to meet the needs of different downstream applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a two-step process flow chart for preparing impregnated asphalt.

[0023] In the figure: 1. Reactor 2. Buffer tank 3. Condenser 4. Light oil collection tank 5. Asphalt collection tank DETAILED DESCRIPTION

[0024] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0025] like Figure 1 As shown, the two-step process for preparing impregnated asphalt according to the present invention comprises the following steps:

[0026] 1) Put petroleum resin into the reactor 1, introduce argon protection, self-pressurize and heat to carry out polymerization reaction, and stop heating when the material reaches the set heating temperature;

[0027] 2) The gas generated by the polymerization reaction in the reactor 1 is released from the top vent valve, and the gas enters the condenser 3 through the buffer tank 2. The tail gas separated by the condenser 3 enters the tail gas collection system, and the separated light oil enters the light oil collection tank 4; when the material temperature in the reactor 1 drops to the set temperature, stop releasing the gas;

[0028] 3) opening the discharge valve at the bottom of the reactor 1 to discharge the cooled material in the reactor 1 as a preliminary product;

[0029] 4) The preliminary product is mixed with the viscosity reducer and then put into the reactor 1 again for heating treatment at normal pressure; the weight ratio of the mixture is 100 parts of the preliminary product and 2-10 parts of the viscosity reducer; after the temperature of the mixture in the reactor 1 reaches the set heating temperature, it is stirred at a constant temperature for a period of time, and then the discharge valve at the bottom of the reactor 1 is opened to discharge the material into the asphalt collection tank 5, and the obtained product is the impregnated asphalt.

[0030] In the step 1), the property indicators of the petroleum resin are: softening point 120-130° C., residual carbon value 30%-35%.

[0031] In the step 1), the set heating temperature of the material during the polymerization reaction is 370-385° C., and the vacuum degree is less than 1 MPa.

[0032] In the step 2), when the temperature of the material in the reactor drops to 290-310° C., the gas release is stopped.

[0033] In the step 4), the viscosity reducing agent is one or more of ethylene glycol, propylene glycol, butylene glycol, glycerol, diethylene glycol and triethylene glycol.

[0034] In the step 4), the set heating temperature of the mixture in the reaction kettle is 200-220° C., and the constant temperature stirring time is 10-60 minutes.

[0035] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0036] [Example 1]

[0037] In this embodiment, the process of preparing impregnated asphalt in two steps is as follows:

[0038] 1) Put petroleum resin (softening point: 122.2°C, residual carbon value: 32.47%) into a reactor, introduce argon protection, and the vacuum degree is 0.8MPa. The reactor is heated according to the set heating curve (25°C insulation for 90min-400°C insulation for 20min-420°C insulation for 30min-450°C) to carry out self-pressure polymerization reaction. When the reactor is heated to 450°C, the temperature of the material in the reactor reaches 370°C, and the heating is stopped at this time;

[0039] 2) The gas generated by the polymerization reaction in the reactor is released from the top vent valve, and the gas enters the condenser through the buffer tank. The tail gas separated by the condenser enters the tail gas collection system, and the separated light oil enters the light oil collection tank; when the material temperature in the reactor drops to 300°C, stop releasing the gas;

[0040] 3) When the temperature of the material in the reactor drops to 280°C, open the discharge valve at the bottom of the reactor to discharge the cooled material in the reactor as the preliminary product;

[0041] 4) The preliminary product is mixed with the viscosity reducer and then put into the reactor again for heating treatment at normal pressure; the weight ratio of the mixture is 100 parts of the preliminary product and 2 parts of the viscosity reducer; after the temperature of the mixture in the reactor reaches 200°C, it is stirred at a constant temperature for 15 minutes, and then the discharge valve at the bottom of the reactor is opened to discharge the material into the asphalt collection tank. The obtained product is impregnated asphalt.

[0042] [Example 2]

[0043] In this embodiment, the process of preparing impregnated asphalt in two steps is as follows:

[0044] 2) Put petroleum resin (softening point 125.6°C, residual carbon value 31.85%) into the reactor, introduce argon protection, vacuum degree 0.7MPa, heat according to the set heating curve (25°C insulation 90min-400°C insulation 20min-420°C insulation 30min-450°C) to carry out self-pressure polymerization reaction. When the reactor is heated to 450°C, the material temperature in the reactor reaches 375°C, and heating is stopped at this time;

[0045] 2) The gas generated by the polymerization reaction in the reactor is released from the top vent valve, and the gas enters the condenser through the buffer tank. The tail gas separated by the condenser enters the tail gas collection system, and the separated light oil enters the light oil collection tank; when the material temperature in the reactor drops to 310°C, stop releasing the gas;

[0046] 3) When the temperature of the material in the reactor drops to 280°C, open the discharge valve at the bottom of the reactor to discharge the cooled material in the reactor as the preliminary product;

[0047] 4) The preliminary product is mixed with the viscosity reducer and then put into the reactor again for heating treatment at normal pressure; the weight ratio of the mixture is 100 parts of the preliminary product and 4 parts of the viscosity reducer; after the temperature of the mixture in the reactor reaches 200°C, it is stirred at a constant temperature for 30 minutes, and then the discharge valve at the bottom of the reactor is opened to discharge the material into the asphalt collection tank. The obtained product is impregnated asphalt.

[0048] [Example 3]

[0049] In this embodiment, the process of preparing impregnated asphalt in two steps is as follows:

[0050] 3) Put petroleum resin (softening point 128.4°C, residual carbon value 34.72%) into the reactor, introduce argon protection, vacuum degree 0.6MPa, heat according to the set heating curve (25°C insulation 90min-400°C insulation 20min-420°C insulation 30min-450°C) to carry out self-pressure polymerization reaction. When the reactor is heated to 450°C, the temperature of the material in the reactor reaches 380°C, and the heating is stopped at this time;

[0051] 2) The gas generated by the polymerization reaction in the reactor is released from the top vent valve, and the gas enters the condenser through the buffer tank. The tail gas separated by the condenser enters the tail gas collection system, and the separated light oil enters the light oil collection tank; when the material temperature in the reactor drops to 290°C, stop releasing the gas;

[0052] 3) When the temperature of the material in the reactor drops to 280°C, open the discharge valve at the bottom of the reactor to discharge the cooled material in the reactor as the preliminary product;

[0053] 4) The preliminary product is mixed with the viscosity reducer and then put into the reactor again for heating treatment at normal pressure; the weight ratio of the mixture is 100 parts of the preliminary product and 6 parts of the viscosity reducer; after the temperature of the mixture in the reactor reaches 205°C, it is stirred at a constant temperature for 15 minutes, and then the discharge valve at the bottom of the reactor is opened to discharge the material into the asphalt collection tank. The obtained product is impregnated asphalt.

[0054] [Comparative Example 1]

[0055] This comparative example adopts a one-step reaction method to prepare the impregnated asphalt, and the preparation process is as follows:

[0056] Put petroleum resin (softening point 123.8℃, residual carbon value 33.52%) into the reactor, pass argon protection, and heat according to the set heating curve (25℃ insulation 90min-400℃ insulation 20min-420℃ insulation 30min-450℃) to carry out self-pressurized polymerization reaction; when the reactor is heated to 450℃, the temperature of the material in the reactor reaches 370℃, then stop heating, open the vent valve on the top of the reactor, send the gas generated during the reaction into the condenser, and the light oil separated by the condenser enters the light oil collection tank. When the temperature of the material in the reactor drops to 300℃, close the vent valve; when the temperature of the material in the reactor drops to 280℃, open the discharge valve at the bottom of the reactor to discharge the material, and the resulting product is impregnated asphalt.

[0057] [Comparative Example 2]

[0058] This comparative example adopts a one-step reaction method to prepare the impregnated asphalt, and the preparation process is as follows:

[0059] 100 parts of petroleum resin (softening point 125.4°C, residual carbon value 32.94%) and 6 parts of viscosity reducer (ethylene glycol) were mixed and put into a reactor. The temperature was raised to 205°C at normal pressure, and the mixture was discharged after constant temperature stirring for 15 minutes. The obtained product was impregnated asphalt.

[0060] The impregnated asphalts prepared in the above Examples 1-3 and Comparative Examples 1 and 2 were tested for indexes, and the softening point, carbon residue value, quinoline insoluble matter and viscosity were tested according to the corresponding national standards. The test results are shown in Table 1.

[0061] Table 1 Asphalt impregnation parameters

[0062]

[0063] It can be seen from the comparison between the above Examples 1-3 and Comparative Examples 1 and 2 that the softening point and carbon residue of the impregnated asphalt prepared by the two-step process of the present invention are significantly better than those of the one-step preparation process of Comparative Examples 1 and 2. The carbon residue value of the impregnated asphalt prepared by Comparative Examples 1 and 2 is significantly inferior, and the viscosity is relatively high at 200°C.

[0064] Conclusion: The impregnated asphalt prepared by the two-step method described in the present invention will have a better impregnation effect in the roasted product. While ensuring the softening point and the residual carbon value, it can also ensure that it has better high-temperature fluidity and can improve the weight gain rate during the impregnation process.

[0065] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A two-step process for preparing impregnated asphalt, characterized in that: The steps include: 1) Put the petroleum resin into the reactor, introduce argon protection, self-pressurize and heat to carry out polymerization reaction, and stop heating when the material reaches the set heating temperature; 2) The gas generated by the polymerization reaction in the reactor is released from the top vent valve, and the gas enters the condenser through the buffer tank. The tail gas separated by the condenser enters the tail gas collection system, and the separated light oil enters the light oil collection tank; when the material temperature in the reactor drops to the set temperature, stop releasing the gas; 3) Open the discharge valve at the bottom of the reactor to discharge the cooled material in the reactor as the preliminary product; 4) The preliminary product is mixed with the viscosity reducer and then put into the reactor again for heating treatment at normal pressure; the weight ratio of the mixture is 100 parts of the preliminary product and 2-10 parts of the viscosity reducer; after the temperature of the mixed material in the reactor reaches the set heating temperature, it is stirred at a constant temperature for a period of time, and then the discharge valve at the bottom of the reactor is opened to discharge the material into the asphalt collection tank, and the obtained product is the impregnated asphalt.

2. A two-step process for preparing impregnated asphalt according to claim 1, characterized in that: In the step 1), the property indicators of the petroleum resin are: softening point 120-130° C., residual carbon value 30%-35%.

3. A two-step process for preparing impregnated asphalt according to claim 1, characterized in that: In the step 1), the set heating temperature of the material during the polymerization reaction is 370-385° C., and the vacuum degree is less than 1 MPa.

4. A two-step process for preparing impregnated asphalt according to claim 1, characterized in that: In the step 2), when the temperature of the material in the reactor drops to 290-310° C., the gas release is stopped.

5. A two-step process for preparing impregnated asphalt according to claim 1, characterized in that: In the step 4), the viscosity reducing agent is one or more of ethylene glycol, propylene glycol, butylene glycol, glycerol, diethylene glycol and triethylene glycol.

6. A two-step process for preparing impregnated asphalt according to claim 1, characterized in that: In the step 4), the set heating temperature of the mixture in the reaction kettle is 200-220° C., and the constant temperature stirring time is 10-60 minutes.

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