System for producing high-temperature heat-conducting oil from phthalic anhydride
By adopting the design of two-stage heating, low-level oil tank and high-level expansion tank in the production of phthalic anhydride, the overpressure problems caused by inaccurate control of thermal oil temperature and water boiling are solved, and the precise control of thermal oil temperature and the stable and safe operation of the system are achieved.
Patent Information
- Application Number
- CN202420354526.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-26
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-02-26
AI Technical Summary
In the production of phthalic anhydride, the temperature control of thermally conductive oil is not accurate, which can easily cause the system to overpressure and inject oil due to boiling water, affecting stable operation and bringing safety hazards.
The two-stage heating method is adopted to use the by-product steam of the phthalic anhydride device for primary heating, and the secondary heating is achieved in combination with electric heating to accurately control the thermally conductive oil temperature; through the synergy between the low-level oil tank and the high-level expansion tank, the overpressure problem caused by water boiling is avoided; nitrogen protection devices are equipped to prevent potential safety risks.
It realizes precise control of the thermal oil temperature, avoids overpressure problems caused by water boiling, improves the stability and safety of the system, and ensures the smooth progress of the production process and the improvement of product quality.
Smart Images
Figure CN222670346U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of phthalic anhydride production equipment, and in particular relates to a high-temperature heat transfer oil system for phthalic anhydride production. Background Art
[0002] In the production of phthalic anhydride, the refining process of crude phthalic anhydride is one of the key links, among which the temperature control of heat transfer oil is crucial to achieve precise heating and meet process requirements. The commonly used heating methods of heat transfer oil are mainly carried out by convection and radiation. The heat transfer oil circulates in the heating system and transfers heat to the equipment or materials that need to be heated through the heat exchanger. In order to make the material temperature meet the process requirements, the heat transfer oil needs to be heated to 280-290°C. The heat transfer oil at room temperature is easy to absorb moisture, and the new heat transfer oil usually contains a certain amount of water. In addition, the unsealed device will also cause water to enter the heat transfer oil. Therefore, at the beginning of the start-up, when the heat transfer oil is heated, the boiling of water will cause the system to overpressure and spray oil, which will lead to poor circulation of the machine pump. This will not only affect the stable operation of the system, but also may bring safety hazards. Therefore, a phthalic anhydride production device that can achieve precise control of the temperature of the heat transfer oil and has an overpressure protection function is needed to improve product quality and production efficiency and ensure the stability and safety of the production process. Utility Model Content
[0003] In view of the above deficiencies in the prior art, the purpose of the utility model is to provide a high-temperature heat transfer oil system for the production of phthalic anhydride, which achieves precise heating of the heat transfer oil temperature while efficiently utilizing the by-product steam of the phthalic anhydride device through a two-stage heating method; the heat transfer oil circulation system effectively solves the overpressure problem caused by water boiling, ensures the stable circulation of the heat transfer oil, and effectively avoids system fluctuations; the automatic control system realizes stable temperature control, improves the degree of automation, reduces manual operation, improves production efficiency, and ensures that the process requirements are met.
[0004] The utility model is realized by adopting the following technical solutions:
[0005] The high-temperature heat transfer oil system for producing phthalic anhydride comprises a heat transfer oil heating system and a heat transfer oil circulation system, wherein the heat transfer oil heating system comprises a heat transfer oil return pipeline, a circulation pump, a steam heater, a heat transfer oil pipeline, an electric heater and a heat transfer oil outlet pipeline which are connected in sequence; the heat transfer oil circulation system comprises a heat transfer oil overpressure pipeline, a high-position expansion tank, a heat transfer oil overflow pipeline, a low-position oil tank, an oil replenishment pump and a heat transfer oil refueling pipeline which are connected in sequence; the outlet of the heat transfer oil refueling pipeline is connected to the inlet of the high-position expansion tank, and the outlet of the high-position expansion tank is also connected to the inlet of the circulation pump through the heat transfer oil replenishment pipeline and the heat transfer oil replenishment pipeline bypass; the outlet of the electric heater is connected to the inlet of the heat transfer oil overpressure pipeline.
[0006] The steam heater is connected with a steam pipeline and a condensate discharge pipeline. The byproduct steam of the phthalic anhydride device enters the steam heater through the steam pipeline to heat the heat transfer oil once. The steam condensate generated after heat exchange with the heat transfer oil returns to the condensate system through the condensate discharge pipeline.
[0007] The electric heater is connected to an automatic control system, and the automatic control system is connected to an electric control device. The electric heater is used to perform secondary heating on the heat transfer oil.
[0008] The outlet of the electric heater is provided with a pressure gauge and a temperature gauge. Under the action of the automatic control system, the electric heater adjusts the electronic control device according to the temperature indication number, thereby realizing precise control of the temperature of the heat transfer oil, and monitoring the pressure of the heat transfer oil system through the pressure gauge.
[0009] An overpressure pipeline safety valve is provided on the heat transfer oil overpressure pipeline. The heat transfer oil is easy to expand during the heating process. In addition, in the initial start-up stage, air will be mixed into the heat transfer oil during circulation, resulting in poor circulation and then overpressure. When overpressure occurs, the heat transfer oil passes through the heat transfer oil overpressure pipeline and the overpressure pipeline safety valve is opened to transport the overpressure heat transfer oil to the high-position expansion tank to ensure the safety and stability of the system.
[0010] The high-level expansion tank is provided with a high-level expansion tank level gauge and an exhaust port, and is also connected to a nitrogen pipeline. The liquid level is monitored by the high-level expansion tank level gauge, and the air in the system, especially at the initial start-up, is discharged through the exhaust port. The high-level expansion tank is nitrogen-sealed and protected through the nitrogen pipeline.
[0011] The low-level oil tank is provided with a low-level oil tank liquid level gauge for monitoring the liquid level of the low-level oil tank.
[0012] An oil replenishing valve is provided on the thermal oil replenishing pipeline, through which the thermal oil in the high-position expansion tank can be quickly transported to the thermal oil heating system; a flow limiting orifice is provided on the bypass of the thermal oil replenishing pipeline, and the thermal oil in the high-position expansion tank can be bypassed through the thermal oil replenishing pipeline. Under the action of the flow limiting orifice, the thermal oil is slowly replenished to the circulation pump inlet through the thermal oil replenishing pipeline to ensure the normal operation of the system.
[0013] The working principle of the utility model is as follows:
[0014] In the thermal oil heating system, the thermal oil from the heated equipment passes through the thermal oil return pipeline and enters the steam heater for primary heating under the action of the circulating pump. The thermal oil after primary heating enters the electric heater through the thermal oil pipeline for secondary heating, raising the thermal oil to the temperature required by the process. After two-stage heating, the thermal oil reaching the process temperature enters the heated equipment through the thermal oil outlet pipeline for use. When the thermal oil system is overpressured, the thermal oil passes through the thermal oil overpressure pipeline and the overpressure pipeline safety valve is opened to transport the overpressure thermal oil to the high-position expansion tank to achieve pressure balance, or the exhaust port is opened to release pressure under nitrogen sealing protection to ensure the stability and safety of the system.
[0015] In the thermal oil circulation system, when it is first started, the purchased thermal oil is filled into the low oil tank and then pumped into the high expansion tank. The thermal oil in the high expansion tank is replenished to the circulation pump inlet through the thermal oil replenishment pipeline and the oil replenishment valve, and then enters the entire system for circulation operation. When the thermal oil heating system is short of oil, the thermal oil in the high expansion tank is slowly replenished to the circulation pump inlet through the thermal oil replenishment pipeline bypass; when the liquid level of the high expansion tank reaches the upper limit, part of the thermal oil in the high expansion tank enters the low oil tank through the thermal oil replenishment pipeline; when the liquid level of the high expansion tank reaches the lower limit, the replenishment pump is turned on to transport the thermal oil in the low oil tank to the high expansion tank to ensure that the thermal oil of the entire system is continuously filled.
[0016] Compared with the prior art, the beneficial effects of the utility model are as follows:
[0017] (1) The high-temperature heat transfer oil system for producing phthalic anhydride of the utility model is carefully designed. First, the by-product steam of the phthalic anhydride device is used for primary heating, which fully utilizes the steam energy and reduces waste. Secondary electric heating is then used for supplementation to ensure that the heat transfer oil can reach the required temperature. The combination of the two-stage heating not only improves the comprehensive utilization efficiency of energy, but also makes the overall heating process more efficient and stable.
[0018] (2) The high-temperature heat transfer oil system for phthalic anhydride production described in the utility model is equipped with a low-level oil tank and a high-level expansion tank, which effectively avoids the problem of system fluctuation caused by water content and moisture absorption of the heat transfer oil at the initial start-up, and water boiling during the heating process, which leads to system overpressure and oil spraying, and then causes poor machine pump circulation. Through the synergistic effect of the low-level oil tank and the high-level expansion tank, the stability of the heat transfer oil during the circulation process is guaranteed, thereby meeting the process requirements and ensuring the smooth progress of the production process;
[0019] (3) The high-temperature heat transfer oil system for producing phthalic anhydride of the utility model can not only effectively prevent potential safety risks by being equipped with a nitrogen protection device, but also isolate the air by nitrogen sealing, thereby maintaining the stability of the oil and extending its service life;
[0020] (4) The high-temperature heat transfer oil system for producing phthalic anhydride described in the utility model can achieve precise control of the temperature of the heat transfer oil through an automatic control system, and can accurately adjust the heating power according to actual needs to keep the temperature of the heat transfer oil stable. It has a high degree of automation, which not only improves production efficiency, but also greatly reduces the need for manual intervention and reduces labor costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is a schematic structural diagram of a high-temperature heat transfer oil system for producing phthalic anhydride according to the utility model;
[0022] In the figure: 1. thermal oil return pipeline; 2. circulation pump; 3. steam heater; 4. condensate discharge pipeline; 5. steam pipeline; 6. thermal oil pipeline; 7. electric heater; 8. automatic control system; 9. electronic control device; 10. pressure gauge; 11. temperature gauge; 12. thermal oil outlet pipeline; 13. thermal oil overpressure pipeline; 14. overpressure pipeline safety valve; 15. high-level expansion tank; 16. high-level expansion tank liquid level gauge; 17. exhaust port; 18. nitrogen pipeline; 19. thermal oil replenishment pipeline; 20. replenishment valve; 21. thermal oil replenishment pipeline bypass; 22. flow limiting orifice; 23. thermal oil overflow pipeline; 24. low-level oil tank; 25. low-level oil tank liquid level gauge; 26. replenishment pump; 27. thermal oil refueling pipeline. DETAILED DESCRIPTION
[0023] In order to make the purpose and technical solution of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings.
[0024] Example 1
[0025] like Figure 1 As shown, the high-temperature heat transfer oil system for producing phthalic anhydride includes a heat transfer oil heating system and a heat transfer oil circulation system, wherein the heat transfer oil heating system includes a heat transfer oil return pipeline 1, a circulation pump 2, a steam heater 3, a heat transfer oil pipeline 6, an electric heater 7 and a heat transfer oil outlet pipeline 12 connected in sequence; the heat transfer oil circulation system includes a heat transfer oil overpressure pipeline 13, a high-position expansion tank 15, a heat transfer oil overflow pipeline 23, a low-position oil tank 24, an oil replenishment pump 26 and a heat transfer oil refueling pipeline 27 connected in sequence; the outlet of the heat transfer oil refueling pipeline 27 is connected to the inlet of the high-position expansion tank 15, and the outlet of the high-position expansion tank 15 is also connected to the inlet of the circulation pump 2 through a heat transfer oil replenishment pipeline 19 and a heat transfer oil replenishment pipeline bypass 21 respectively; the outlet of the electric heater 7 is connected to the inlet of the heat transfer oil overpressure pipeline 13.
[0026] The steam heater 3 is connected to a steam pipeline 5 and a condensate discharge pipeline 4 .
[0027] The electric heater 7 is connected to an automatic control system 8 , and the automatic control system 8 is connected to an electric control device 9 .
[0028] The outlet of the electric heater 7 is provided with a pressure gauge 10 and a temperature gauge 11 .
[0029] The heat transfer oil overpressure pipeline 13 is provided with an overpressure pipeline safety valve 14 .
[0030] The high-position expansion tank 15 is provided with a high-position expansion tank level gauge 16 and an exhaust port 17 , and is also connected to a nitrogen pipeline 18 .
[0031] The low-level oil tank 24 is provided with a low-level oil tank liquid level gauge 25 .
[0032] The heat transfer oil replenishment pipeline 19 is provided with an oil replenishment valve 20 , and the heat transfer oil replenishment pipeline bypass 21 is provided with a flow limiting orifice 22 .
[0033] When working, the specific steps are as follows:
[0034] The heat transfer oil enters the circulation pump 2 from the heated equipment through the heat transfer oil return pipeline 1, and then enters the steam heater 3, and is heated once using the by-product steam in the phthalic anhydride production process. The heated heat transfer oil enters the electric heater 7 through the heat transfer oil pipeline 6. Under the control of the automatic control system 8, the electric heater 7 performs secondary heating according to the feedback of the temperature meter 11 to accurately control the temperature of the heat transfer oil. After completing the two-stage heating, the heat transfer oil reaches the temperature required by the process and enters the heated equipment again through the heat transfer oil outlet pipeline 12.
[0035] During the heating process, if the thermal oil system is over-pressured, the over-pressured thermal oil will be transported to the high-position expansion tank 15 through the thermal oil over-pressure pipeline 13 and the over-pressure pipeline safety valve 14 to achieve pressure balance. At the same time, the nitrogen protection in the high-position expansion tank 15 can isolate the air and keep the oil stable. When the system is first started, some air is mixed into the thermal oil, and then it is discharged through the exhaust port 17 of the high-position expansion tank 15.
[0036] In addition, the thermal oil circulation system ensures the stable flow of thermal oil. When the system is first started, the purchased thermal oil is first filled into the low oil tank 24 and then pumped into the high expansion tank 15. The thermal oil in the high expansion tank 15 is replenished to the inlet of the circulation pump 2 through the oil replenishment valve 20 and the thermal oil replenishment pipeline 19, thereby starting the circulation of the entire system. When the thermal oil heating system is short of oil, the thermal oil in the high expansion tank 15 can be slowly replenished to the circulation pump 2 through the thermal oil replenishment pipeline bypass 21. When the liquid level of the high expansion tank 15 changes, the thermal oil will circulate between the low oil tank 24 and the high expansion tank 15 to keep the thermal oil in the system continuously full. The comprehensive utilization of steam energy and the efficient heating of thermal oil are achieved through two-stage heating, and the stable operation of the system is ensured through the circulation and oil replenishment mechanism. At the same time, measures such as nitrogen protection and overpressure safety valve are used to improve the safety of the system.
Claims
1. A high-temperature heat transfer oil system for producing phthalic anhydride, characterized in that: The invention comprises a heat transfer oil heating system and a heat transfer oil circulation system, wherein the heat transfer oil heating system comprises a heat transfer oil return pipeline (1), a circulation pump (2), a steam heater (3), a heat transfer oil pipeline (6), an electric heater (7) and a heat transfer oil outlet pipeline (12) which are connected in sequence; the heat transfer oil circulation system comprises a heat transfer oil overpressure pipeline (13), a high-position expansion tank (15), a heat transfer oil overflow pipeline (23), a low-position oil tank (24), an oil replenishment pump (26) and a heat transfer oil refueling pipeline (27) which are connected in sequence; the outlet of the heat transfer oil refueling pipeline (27) is connected to the inlet of the high-position expansion tank (15), and the outlet of the high-position expansion tank (15) is also connected to the inlet of the circulation pump (2) through a heat transfer oil replenishment pipeline (19) and a heat transfer oil replenishment pipeline bypass (21); the outlet of the electric heater (7) is connected to the inlet of the heat transfer oil overpressure pipeline (13).
2. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The steam heater (3) is connected to a steam pipeline (5) and a condensate discharge pipeline (4).
3. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The electric heater (7) is connected to an automatic control system (8), and the automatic control system (8) is connected to an electric control device (9).
4. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The outlet of the electric heater (7) is provided with a pressure gauge (10) and a temperature gauge (11).
5. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The heat transfer oil overpressure pipeline (13) is provided with an overpressure pipeline safety valve (14).
6. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The high-position expansion tank (15) is provided with a high-position expansion tank liquid level gauge (16) and an exhaust port (17), and is also connected to a nitrogen pipeline (18).
7. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The low-level oil tank (24) is provided with a low-level oil tank liquid level gauge (25).
8. The high-temperature heat transfer oil system for producing phthalic anhydride according to claim 1, characterized in that: The heat transfer oil replenishment pipeline (19) is provided with an oil replenishment valve (20), and the heat transfer oil replenishment pipeline bypass (21) is provided with a flow limiting orifice plate (22).