A production process of aromatic heat transfer oil

Abstract

A production process of aromatic heat transfer oil belongs to the field of heat transfer medium technology. It includes the following steps: the raw material crude aromatic component material is separated by rectification at a pressure of ‑0.09MPa to obtain the heavy component after the fraction before 230°C is pumped into a twin-screw devolatilizer, the jacket temperature of the twin-screw devolatilizer is controlled at 265°C to 270°C, and the devolatilization port of the twin-screw devolatilizer is connected to a condensation vacuum system; the gas phase removed from the devolatilization port is condensed into an aromatic heat transfer oil base oil, and the remaining material extracted from the discharge port of the twin-screw devolatilizer is used as a rubber softener. This production process not only improves product quality and production efficiency, reduces production costs, but also enhances environmental friendliness, improves economic benefits, and meets the requirements of sustainable development.

Description

Technical Field

[0001] The invention discloses a production process of aromatic heat transfer oil, belonging to the technical field of heat transfer media. Background Art

[0002] Heat transfer oil, also known as heat transfer oil, is a heat transfer medium with high temperature and low pressure heat transfer performance, high thermal efficiency, uniform heat transfer, accurate temperature control, convenient transportation and long service life. It has become the most widely used and largest liquid heat carrier. Among them, aromatic heat transfer oil is widely used in the field of chemical product production raw materials, such as chemical reaction heating and cooling, heat transfer medium, steam generator, etc. It can also be used in the rubber products industry to improve the processing properties of rubber, enhance the resistance of rubber products to weathering, oxidation, friction and aging, and help mix and disperse fillers in rubber.

[0003] Aromatic heat transfer oil has good heat transfer performance, can effectively transfer heat, improve heating and cooling efficiency, usually contains a high proportion of aromatic hydrocarbons, the content can reach 70% to 87%, saturated hydrocarbon content is 20% to 35%, polar content is less than 25%, asphalt olefin content is less than 0.5%. It has the characteristics of a dark viscous liquid, the viscosity (60℃) is 12 to 15°E, the flash point (open cup) is between 170 and 200℃, and the aniline point is about 36℃. Aromatic heat transfer oil has good thermal stability, can maintain stable chemical and physical properties at high temperatures, and is not easy to decompose and deteriorate. At the same time, it has a low viscosity, which makes it have good fluidity during heating and cooling, and is easy to transport and pump. In addition, aromatic heat transfer oil has a high flash point, is not easy to burn, and is highly safe to use.

[0004] The main preparation method at present is to put heavy aromatics above C10 and alkylating agents into a reactor in a certain proportion, add a catalyst, stir the reaction at 60-120°C for 5-10 hours, and then cut the fractions of different distillation ranges through distillation operation for the preparation of high-temperature heat transfer oil base oil. The raw material cost is relatively high. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a production process for aromatic heat transfer oil with low raw material cost and high production efficiency.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a production process of aromatic heat transfer oil, characterized in that it comprises the following steps:

[0007] 1) The crude aromatic component material is distilled at a pressure of -0.09 MPa to separate the fraction before 230°C and then collect the heavy component;

[0008] 2) Pumping the obtained heavy component into a twin-screw devolatilizer, controlling the jacket temperature of the twin-screw devolatilizer at 265° C. to 270° C., connecting the devolatilization port of the twin-screw devolatilizer to a condensation vacuum system; the gas phase discharged from the devolatilization port is condensed into an aromatic heat transfer oil base oil, and the remaining material collected from the discharge port of the twin-screw devolatilizer is used as a rubber softener.

[0009] The production process of the aromatic heat transfer oil uses low-cost crude aromatic component materials as raw materials, and realizes the rapid separation of high-purity vapor phase aromatic heat transfer oil base oil and rubber softener through precise process control. Generally, a twin-screw devolatilizer is an extrusion molding equipment, which is mainly used to separate low relative molecular mass components from a polymer system, generally to achieve the separation of solid (or molten state) and gas phase. The present invention uses a twin-screw devolatilizer to process the heavy component part of the high-viscosity crude aromatic component material, and efficiently separates it into aromatic heat transfer oil base oil and rubber softener.

[0010] When faced with how to separate the heavy components of the crude aromatic component material, the present invention abandons the traditional distillation tower and adopts the extrusion molding equipment twin-screw devolatilizer. Compared with the distillation treatment using the distillation tower, because there is no large temperature difference between the top and the bottom of the tower, the required energy consumption is lower. Moreover, the twin screws therein can continuously stir and shear the material, and can more quickly separate the aromatic heat transfer oil base oil component from the material.

[0011] Preferably, the condensation vacuum system described in step 2) of the above production process includes a cooler and a product buffer tank, the devolatilization port is connected to the cooler, the condensate outlet of the cooler is connected to the product buffer tank, and the top of the product buffer tank is connected to the vacuum system.

[0012] The vacuum point of the system is the top of the product buffer tank. Since the gas phase material at the devolatilization port is very heavy, the maximum vacuum degree is required. Therefore, there is no need to control the vacuum degree of the product buffer tank. At the same time, by connecting the vacuum system, the pressure of the product buffer tank is effectively reduced, the separation efficiency is improved, and the operation is simplified.

[0013] More preferably, the gas phase released from the devolatilization port (or exhaust port) is cooled by a cooler and flows into a product buffer tank, and then flows from the product buffer tank into a reflux pump by gravity, and is pressurized by the reflux pump, and then metered by a flow meter and pumped back to the feed port of the twin-screw devolatilizer as reflux. By setting the reflux pump and the flow meter, the reflux amount can be accurately controlled to ensure the stability and efficiency of the separation process.

[0014] More preferably, the product buffer tank is also connected to a production pump, which is used to pressurize and produce the aromatic heat transfer oil base oil, and the production volume is 7.4% to 8.7% of the raw material feed volume. Accurate production volume control and the setting of product aftercooler ensure that the temperature of the produced material is within an appropriate range, ensuring the stability and safety of the product.

[0015] More preferably, a product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 36°C to 45°C by means of the product aftercooler.

[0016] More preferably, the discharge port of the twin-screw devolatilizer is connected to a circulation line returning to the twin-screw devolatilizer and a nitrogen purge port.

[0017] Since the output of rubber softener is too small and the material is viscous, a circulation line and a nitrogen purge port are added to ensure that the rubber softener output pump is always running and prevent the material from condensing into solids in the pipeline and blocking the pipeline.

[0018] Preferably, the jacket of the twin-screw devolatilizer described in step 2) of the above production process is divided into three sections: front, middle and rear by a partition, the temperature of the front section jacket is controlled at 265°C to 267°C, the temperature of the middle section jacket is controlled at 267°C to 269°C, and the temperature of the rear section jacket is controlled at 268°C to 270°C.

[0019] In order to gradually increase the temperature of the material in the twin-screw devolatilizer as it advances, the jacket is divided into three sections: front, middle and rear by partitions. Of course, it can also be divided into more sections to make the temperature difference between adjacent partitions smaller and more stable.

[0020] As the light component of aromatic heat transfer oil base oil is released, the viscosity of the material gradually increases, and the twin-screw devolatilizer gradually increases the temperature, which is conducive to the faster and more thorough release of the light component. If the temperature is directly increased when entering the twin-screw devolatilizer, the release rate will be uneven before and after, and if the release rate is too fast in the early stage, a small amount of heavy components will be brought out, affecting the product quality of the aromatic heat transfer oil base oil.

[0021] The efficient mixing ability of the twin-screw extruder is the key to achieving devolatilization. Under the strong shearing and mixing action of the screw, the light components in the material are more easily released. This mixing and shearing action not only increases the diffusion rate of the light components that can be used as the base oil of aromatic heat transfer oil, but also helps to separate it from the material.

[0022] More preferably, the screw speed of the twin-screw devolatilizer is 120 r / min to 155 r / min. The viscosity of the crude aromatic component after light devolatilization is relatively large, and the mixing and shearing effects provided by the appropriate speed can ensure the full separation of the light component.

[0023] More preferably, the feed rate of the twin-screw devolatilizer is controlled to keep the material in the inner barrel of the twin-screw devolatilizer occupying 50% to 80% of the volume. Controlling the volume proportion of the material can enhance the mixing and shearing effects and effectively prevent the liquid phase components from being vacuumed out.

[0024] More preferably, the aspect ratio of the inner barrel of the twin-screw devolatilizer is 80 to 95: 1. The present invention adopts an inner barrel with a larger aspect ratio, which can better control the temperature distribution of the material, especially in the temperature control of different sections, which helps to achieve the gradual increase of the temperature of the material during the devolatilization process, and at the same time provides a stronger mixing and shearing effect, promoting the release and separation of the light components of the aromatic heat transfer oil base oil.

[0025] Preferably, the crude aromatic component material of the raw material described in step 1) of the above production process is separated by distillation at a pressure of -0.09 MPa to obtain a fraction before 230°C for use as a PVC plasticizer. This fraction accounts for the vast majority of the crude aromatic component material of the raw material, and the preparation process of the aromatic heat transfer oil of the present invention is actually the reuse of the PVC plasticizer tail material.

[0026] Compared with the prior art, the present invention has the following beneficial effects: the present invention uses relatively low-cost crude aromatic component materials as raw materials, produces high-purity products through precise process control, and effectively reduces the cost of raw materials. Compared with the traditional distillation tower, the large temperature difference between the top and the bottom of the tower is avoided, and the energy consumption is reduced. The stirring and shearing action of the twin-screw devolatilizer accelerates the separation of the aromatic heat transfer oil base oil components and improves the production efficiency. This production process simplifies the operation process, reduces the complexity of the equipment, and reduces the difficulty of operation. The design of the condensation vacuum system and the product buffer tank improves the separation efficiency, and the setting of the reflux pump and the flowmeter ensures the stability and efficiency of the separation process. Accurate extraction control and the setting of the product aftercooler ensure the stability and safety of the product. The jacket segmented temperature control of the twin-screw devolatilizer is conducive to the rapid removal of light components and improves the product quality. The entire process has strong adaptability, and the operating parameters can be adjusted according to production needs, while reducing environmental impact. DETAILED DESCRIPTION

[0027] The present invention is described in detail below by way of examples. Unless otherwise specified, the raw materials used are purchased crude aromatic component materials. Each example is carried out using the same batch.

[0028] Example 1

[0029] 1) The crude aromatic component material is distilled at a pressure of -0.09 MPa to separate the fraction before 230°C for use as a PVC plasticizer, and the remaining heavy components are collected, accounting for 10.1% of the feed amount of the crude aromatic component material.

[0030] 2) The obtained heavy component is pumped into a twin-screw devolatilizer, the length-diameter ratio of the inner barrel of the twin-screw devolatilizer is 90:1, and the feeding rate of the twin-screw devolatilizer is controlled to keep the material in the inner barrel of the twin-screw devolatilizer occupying 65% of the volume. The jacket of the twin-screw devolatilizer is divided into three sections: front, middle and back by a partition, the jacket temperature of the front section is controlled at 266°C, the jacket temperature of the middle section is controlled at 268°C, the jacket temperature of the back section is controlled at 269°C, and the screw speed of the twin-screw devolatilizer is 135r / min.

[0031] The gas phase from the devolatilizer outlet of the twin-screw devolatilizer is cooled by the cooler and flows into the product buffer tank. Then, it flows into the reflux pump by gravity from the product buffer tank. After being pressurized by the reflux pump, it is metered by the flow meter and then pumped back to the feed port of the twin-screw devolatilizer as reflux. The product buffer tank is connected to a production pump, which is used to pressurize and produce aromatic heat transfer oil base oil. The production volume is 8.3% of the feed volume of the raw crude aromatic component material. A product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 40°C by the product aftercooler.

[0032] The discharge port of the twin-screw devolatilizer is connected to a circulation line returning to the twin-screw devolatilizer and a nitrogen purge port. The remaining material extracted from the discharge port of the twin-screw devolatilizer is used as a rubber softener, and the extraction amount in this example is 1.8% of the feed amount of the raw material crude aromatic component.

[0033] Example 2

[0034] The heavy component obtained in step 1) of Example 1 is pumped into a twin-screw devolatilizer, the length-to-diameter ratio of the inner barrel of the twin-screw devolatilizer is 85:1, and the feed rate of the twin-screw devolatilizer is controlled to maintain that the material in the inner barrel of the twin-screw devolatilizer occupies 70% of the volume. The jacket of the twin-screw devolatilizer is divided into three sections: front, middle and back by a partition, the jacket temperature of the front section is controlled at 266°C, the jacket temperature of the middle section is controlled at 268°C, and the jacket temperature of the back section is controlled at 269°C, and the screw speed of the twin-screw devolatilizer is 130r / min.

[0035] The gas phase from the devolatilizer outlet of the twin-screw devolatilizer is cooled by the cooler and flows into the product buffer tank. Then, it flows into the reflux pump by gravity from the product buffer tank. After being pressurized by the reflux pump, it is metered by the flow meter and then pumped back to the feed port of the twin-screw devolatilizer as reflux. The product buffer tank is connected to a production pump, which is used to pressurize and produce aromatic heat transfer oil base oil. The production volume is 8.5% of the feed volume of the raw crude aromatic component material. A product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 42°C by the product aftercooler.

[0036] The discharge port of the twin-screw devolatilizer is connected to a circulation line returning to the twin-screw devolatilizer and a nitrogen purge port. The remaining material extracted from the discharge port of the twin-screw devolatilizer is used as a rubber softener, and the extraction amount in this example is 1.6% of the feed amount of the raw material crude aromatic component.

[0037] Example 3

[0038] The heavy component obtained in step 1) of Example 1 is pumped into a twin-screw devolatilizer, the length-to-diameter ratio of the inner barrel of the twin-screw devolatilizer is 92:1, and the feed rate of the twin-screw devolatilizer is controlled to maintain that the material in the inner barrel of the twin-screw devolatilizer occupies 60% of the volume. The jacket of the twin-screw devolatilizer is divided into three sections: front, middle and back by a partition, the jacket temperature of the front section is controlled at 266°C, the jacket temperature of the middle section is controlled at 268°C, the jacket temperature of the back section is controlled at 269°C, and the screw speed of the twin-screw devolatilizer is 140r / min.

[0039] The gas phase from the devolatilizer outlet of the twin-screw devolatilizer is cooled by the cooler and flows into the product buffer tank, and then flows into the reflux pump by gravity from the product buffer tank. After being pressurized by the reflux pump, it is metered by the flow meter and then pumped back to the feed port of the twin-screw devolatilizer as reflux. The product buffer tank is connected to a production pump, which is pressurized and produced as aromatic heat transfer oil base oil through the production pump. The production volume is 7.8% of the feed volume of the raw crude aromatic component material. A product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 38°C by the product aftercooler.

[0040] The discharge port of the twin-screw devolatilizer is connected to a circulation line returning to the twin-screw devolatilizer and a nitrogen purge port. The remaining material extracted from the discharge port of the twin-screw devolatilizer is used as a rubber softener. In this example, the extraction amount is 2.3% of the feed amount of the raw material crude aromatic component.

[0041] Example 4

[0042] The heavy component obtained in step 1) of Example 1 is pumped into a twin-screw devolatilizer, the length-to-diameter ratio of the inner barrel of the twin-screw devolatilizer is 80:1, and the feed rate of the twin-screw devolatilizer is controlled to maintain that the material in the inner barrel of the twin-screw devolatilizer occupies 50% of the volume. The jacket of the twin-screw devolatilizer is divided into three sections: front, middle and back by a partition, the jacket temperature of the front section is controlled at 265°C, the jacket temperature of the middle section is controlled at 267°C, and the jacket temperature of the back section is controlled at 268°C, and the screw speed of the twin-screw devolatilizer is 155r / min.

[0043] The gas phase from the devolatilizer outlet of the twin-screw devolatilizer is cooled by the cooler and flows into the product buffer tank, and then flows into the reflux pump by gravity from the product buffer tank. After being pressurized by the reflux pump, it is metered by the flow meter and then pumped back to the feed port of the twin-screw devolatilizer as reflux. The product buffer tank is connected to a production pump, which is pressurized and produced as aromatic heat transfer oil base oil through the production pump. The production volume is 7.4% of the feed volume of the raw crude aromatic component material. A product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 36°C by the product aftercooler.

[0044] The discharge port of the twin-screw devolatilizer is connected to a circulation line returning to the twin-screw devolatilizer and a nitrogen purge port. The remaining material extracted from the discharge port of the twin-screw devolatilizer is used as a rubber softener, and the extraction amount in this example is 2.7% of the feed amount of the raw material crude aromatic component.

[0045] Example 5

[0046] The heavy component obtained in step 1) of Example 1 is pumped into a twin-screw devolatilizer, the length-to-diameter ratio of the inner barrel of the twin-screw devolatilizer is 95:1, and the feed rate of the twin-screw devolatilizer is controlled to maintain that the material in the inner barrel of the twin-screw devolatilizer occupies 80% of the volume. The jacket of the twin-screw devolatilizer is divided into three sections: front, middle and back by a partition, the jacket temperature of the front section is controlled at 267°C, the jacket temperature of the middle section is controlled at 269°C, and the jacket temperature of the back section is controlled at 270°C, and the screw speed of the twin-screw devolatilizer is 120r / min.

[0047] The gas phase from the devolatilizer outlet of the twin-screw devolatilizer is cooled by the cooler and flows into the product buffer tank, and then flows into the reflux pump by gravity from the product buffer tank. After being pressurized by the reflux pump, it is metered by the flow meter and then pumped back to the feed port of the twin-screw devolatilizer as reflux. The product buffer tank is connected to a production pump, which is pressurized and produced as aromatic heat transfer oil base oil through the production pump. The production volume is 8.7% of the feed volume of the raw crude aromatic component material. A product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 45°C by the product aftercooler.

[0048] The discharge port of the twin-screw devolatilizer is connected to a circulation line returning to the twin-screw devolatilizer and a nitrogen purge port. The remaining material extracted from the discharge port of the twin-screw devolatilizer is used as a rubber softener, and the extraction amount in this example is 1.4% of the feed amount of the raw material crude aromatic component.

[0049] Comparative Example 1

[0050] The heavy component obtained in step 1 of Example 1 enters the middle part of the distillation tower, and the top temperature of the distillation tower is controlled to be 261°C, the bottom temperature is 301°C, and the system pressure is -0.096MPa. The material is divided into two parts in the distillation tower, and the gas phase aromatic heat transfer oil base oil is distilled out from the top of the tower; a part is cooled by the top raw material preheater, and then the gas-liquid phase is mixed and enters the top product cooler, and is completely cooled into liquid in the top product condenser. Then it flows into the top product buffer tank by gravity, and then flows from the top product buffer tank by gravity into the top reflux pump. After being pressurized by the top reflux pump, it is measured and controlled by the top reflux flowmeter and then returned to the top of the tower as reflux to ensure the normal operation of the distillation tower. The system vacuum point is set at the top product buffer tank.

[0051] After the tower top extraction pump is pressurized, the extraction amount of the tower top product is controlled by controlling the liquid level of the tower top buffer tank. The extraction amount is 8.3% of the raw material mass. In order to control the final extraction temperature of the product, the product aftercooler is used to control the extraction material temperature at 42°C.

[0052] The bottom of the tower is used as a rubber softener. After being pressurized by the bottom extraction pump, the bottom extraction volume is controlled by controlling the bottom liquid level of the distillation tower. Since the extraction volume is too small and the material is relatively viscous, an additional circulation line is used to ensure that the bottom pump is always running. A nitrogen purge port is added. After each material is delivered, it is purged again with nitrogen to prevent the material from condensing into solids in the pipeline and blocking the pipeline.

[0053] The heat source of the distillation tower is provided by the reboiler at the bottom of the tower through heat exchange with the heat transfer oil. The temperature at the bottom of the tower is controlled by controlling the amount of heat transfer oil entering the reboiler.

[0054] The forced circulation pump at the bottom of the tower is used to increase the circulation volume from the bottom of the tower to the reboiler and from the reboiler to the kettle.

[0055] The aromatic heat transfer oil base oil obtained in the examples and comparative examples was subjected to performance testing according to the evaluation method disclosed in patent CN 106610387A. The test results are shown in Table 1.

[0056] Table 1 Performance test results

[0057]

[0058]

[0059] It can be seen from Table 1 that the various properties of the aromatic heat transfer oil base oil prepared by the devolatilizer of the present invention are comparable to those of the heat transfer oil prepared by the distillation method.

[0060] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A production process for aromatic heat transfer oil, characterized in that: The following steps are involved: 1) The crude aromatic component material is distilled at a pressure of -0.09 MPa to separate the fraction before 230°C and then collect the heavy component; 2) Pumping the obtained heavy component into a twin-screw devolatilizer, controlling the jacket temperature of the twin-screw devolatilizer at 265° C. to 270° C., connecting the devolatilization port of the twin-screw devolatilizer to a condensation vacuum system; the gas phase discharged from the devolatilization port is condensed into an aromatic heat transfer oil base oil, and the remaining material collected from the discharge port of the twin-screw devolatilizer is used as a rubber softener.

2. The production process of an aromatic heat transfer oil according to claim 1, characterized in that: The condensation vacuum system described in step 2) includes a cooler and a product buffer tank, the devolatilization port is connected to the cooler, the condensate outlet of the cooler is connected to the product buffer tank, and the top of the product buffer tank is connected to a vacuum system.

3. The production process of an aromatic heat transfer oil according to claim 2, characterized in that: The gas phase released from the devolatilizer is cooled by a cooler and flows into a product buffer tank, and then flows from the product buffer tank into a reflux pump, is pressurized by the reflux pump, and then measured by a flow meter and pumped back to the feed port of the twin-screw devolatilizer as reflux.

4. The production process of an aromatic heat transfer oil according to claim 3, characterized in that: The product buffer tank is also connected to a production pump, which is used to produce aromatic heat transfer oil base oil under pressure, and the production volume is 7.4% to 8.7% of the raw material feed volume.

5. The production process of an aromatic heat transfer oil according to claim 4, characterized in that: A product aftercooler is provided on the discharge port of the production pump, and the temperature of the produced aromatic heat transfer oil base oil is controlled at 36°C to 45°C by means of the product aftercooler.

6. The production process of an aromatic heat transfer oil according to claim 1, characterized in that: The jacket of the twin-screw devolatilizer is divided into three sections: front, middle and rear by partitions. The temperature of the front jacket is controlled at 265°C-267°C, the temperature of the middle jacket is controlled at 267°C-269°C, and the temperature of the rear jacket is controlled at 268°C-270°C.

7. A production process for aromatic heat transfer oil according to claim 1 or 6, characterized in that: The screw speed of the twin-screw devolatilizer is 120 r / min to 155 r / min.

8. The production process of an aromatic heat transfer oil according to claim 1, characterized in that: The feeding rate of the twin-screw devolatilizer is controlled to keep the material in the inner barrel of the twin-screw devolatilizer occupying 50% to 80% of the volume.

9. The production process of aromatic heat transfer oil according to claim 8, characterized in that: The length-to-diameter ratio of the inner barrel of the twin-screw devolatilizer is 80-95:

1.

10. The production process of aromatic heat transfer oil according to claim 1, characterized in that: The crude aromatic component material of the raw material in step 1) is separated by distillation at a pressure of -0.09 MPa to obtain a fraction below 230° C. for use as a PVC plasticizer.

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