Circulating system for removing gas-phase impurities in phthalic anhydride and phthalic anhydride production system

Abstract

The utility model provides a circulating system for removing gas-phase impurities in phthalic anhydride and a phthalic anhydride production system, and belongs to the technical field of phthalic anhydride production. The circulating system comprises a switching condenser and an oil cooling system, the oil cooling system comprises an oil cooling tank and a cooler, the oil cooling tank is communicated with the cooler, and the cooler is communicated with an inlet of a finned tube of the switching condenser; the hot oil system comprises a hot oil tank and a steam heater, the hot oil tank is communicated with the steam heater, and the steam heater is communicated with an inlet of the finned tube of the switching condenser; the oil supplementing system at least comprises an oil storage tank, an expansion tank and an electric heater, the expansion tank is provided with a first liquid inlet, a liquid phase outlet and a gas phase outlet, the first liquid inlet is communicated with the oil storage tank, the liquid phase outlet is communicated with the electric heater, the gas phase outlet is communicated with the outside, and the electric heater is communicated with an inlet of the finned tube of the switching condenser. According to the circulating system, cold oil and hot oil can be supplemented to the switching condenser at any time by arranging the oil supplementing system, so that the operation stability of the switching condenser is guaranteed.

Description

Technical Field

[0001] The utility model belongs to the field of phthalic anhydride production technology, and specifically relates to a circulation system for removing gas phase impurities in phthalic anhydride and a phthalic anhydride production system. Background Art

[0002] At present, in the phthalic anhydride production process, four or five switching condensers are used to perform periodic operations of material desublimation and melting to achieve the purpose of removing side reaction gas phase impurities in crude phthalic anhydride. Among them, material desublimation and melting are achieved through a thermal oil circulation system. The temperature control of the thermal oil circulation system is directly related to the operating efficiency of the switching condenser. With the continuous operation of the thermal oil system, there will be problems such as insufficient circulating cold oil or circulating hot oil and large deviation in oil temperature control, which will affect the operating stability of the switching condenser. Utility Model Content

[0003] In view of the above problems existing in the prior art, the purpose of the embodiments of the utility model is to provide a circulation system for removing gaseous impurities in phthalic anhydride and a phthalic anhydride production system. The circulation system can replenish cold oil and hot oil for the switching condenser at any time by setting an oil replenishment system, and can quickly and stably adjust the oil temperature to ensure the operating stability of the switching condenser.

[0004] The technical solution adopted in the embodiment of the utility model is:

[0005] A circulation system for removing gas-phase impurities in phthalic anhydride, comprising a switching condenser, the circulation system further comprising:

[0006] A cold oil system, comprising a cold oil tank and a cooler, wherein the oil outlet of the cold oil tank is connected to the oil inlet of the cooler through a first oil pump, and the oil outlet of the cooler is connected to the inlet of the fin tube of the switch condenser;

[0007] A hot oil system, comprising a hot oil tank and a steam heater, wherein the oil outlet of the hot oil tank is connected to the oil inlet of the steam heater via a second oil pump, and the oil outlet of the steam heater is connected to the inlet of the finned tube of the switch condenser;

[0008] The oil replenishment system at least includes an oil storage tank, an expansion tank and an electric heater, wherein the expansion tank has at least a first liquid inlet, a liquid phase outlet and a gas phase outlet, the first liquid inlet is connected to the outlet of the oil storage tank, the liquid phase outlet is connected to the oil inlet of the electric heater through a third oil pump, the gas phase outlet is connected to the outside, and the oil outlet of the electric heater is connected to the inlet of the fin tube of the switching condenser.

[0009] Furthermore, the circulation system also includes a first three-way liquid-phase valve and a second three-way liquid-phase valve, the first three-way liquid-phase valve is used to connect the inlet of the fin tube of the switching condenser, the oil outlet of the cooler and the oil outlet of the steam heater, and the second three-way liquid-phase valve is used to connect the outlet of the fin tube of the switching condenser, the oil inlet of the cold oil tank and the oil inlet of the hot oil tank.

[0010] Furthermore, an oil-gas separator is provided on the pipeline connecting the liquid phase outlet of the expansion tank and the oil inlet of the third oil pump.

[0011] Furthermore, the oil storage tank, the expansion tank, the cold oil tank and the hot oil tank are respectively provided with liquid level gauges for detecting the height of the internal liquid.

[0012] Furthermore, the circulation system also includes a nitrogen system, the cold oil tank, the hot oil tank and the expansion tank are respectively connected to nitrogen pipelines, and the nitrogen system is in communication with the nitrogen pipelines.

[0013] Furthermore, the expansion tank is provided with a second liquid inlet, and the oil outlet of the first oil pump is also connected to the second liquid inlet.

[0014] Furthermore, the oil outlet of the second oil pump is also connected to the hot oil tank through an oil return pipeline, and an oil filter is provided on the oil return pipeline.

[0015] Furthermore, the oil inlet of the oil storage tank is connected to an oil filling pipeline, and the oil outlet of the oil storage tank is connected to the oil inlet of the expansion tank through a fourth oil pump.

[0016] A phthalic anhydride production system, comprising the circulation system for removing gas phase impurities in phthalic anhydride as described in any one of the above phthalic anhydride production systems.

[0017] Compared with the prior art, the beneficial effects of the embodiments of the present invention are:

[0018] In the circulation system for removing gaseous impurities in phthalic anhydride of the utility model, the circulating cold oil or circulating hot oil can be respectively supplemented into the switching condenser by setting an oil supplement system to ensure the operation stability of the switching condenser. When hot oil needs to be supplemented, the electric heater can be started; when cold oil needs to be supplemented, the electric heater does not need to be started. At the same time, the electric heater in the oil supplement system can effectively improve the dehydration and degassing of the circulating hot oil during the start-up process, stabilize the circulating temperature of the circulating hot oil in the system, speed up the production progress, reduce energy consumption, and save energy.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the embodiments of the utility model. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts.

[0021] Figure 1 The present invention is a schematic diagram of the structure of a circulation system for removing gas-phase impurities in phthalic anhydride according to an embodiment of the present invention.

[0022] In the figure: 1-oil filling hose; 2-fourth oil pump; 3-oil storage tank; 4-expansion tank; 5-oil-gas separator; 6-third oil pump; 7-electric heater; 8-cold oil tank; 9-first oil pump; 10-cooler; 11-first three-way liquid phase valve; 12-switching condenser; 13-second three-way liquid phase valve; 14-hot oil tank; 15-second oil pump; 16-oil filter; 17-steam heater; 18-medium-pressure steam pipeline; 19-first nitrogen pipeline; 20-second nitrogen pipeline. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] The utility model embodiment provides a circulation system for removing gas phase impurities in phthalic anhydride, such as Figure 1 As shown, the circulation system includes a switch condenser 12, a cold oil system, a hot oil system and an oil replenishment system.

[0025] The cold oil system includes a cold oil tank 8 and a cooler 10. The cold oil tank 8 is used to buffer and store circulating cold oil, and the cooler 10 is used to control the temperature of the circulating cold oil. The oil outlet of the cold oil tank 8 is connected to the oil inlet of the cooler 10 through the first oil pump 9. The oil outlet of the cooler 10 is connected to the inlet of the finned tube of the switching condenser 12. The first oil pump 9 can pump the circulating cold oil in the cold oil tank 8 into the cooler 10 for cooling, and send it to the finned tube of the switching condenser 12 after it is cooled to a preset temperature.

[0026] The hot oil system includes a hot oil tank 14 and a steam heater 17. The hot oil tank 14 is used for buffering and storing circulating hot oil, and the steam heater 17 is used for controlling the temperature of the circulating hot oil. The oil outlet of the hot oil tank 14 is connected to the oil inlet of the steam heater 17 through the second oil pump 15, and the oil outlet of the steam heater 17 is connected to the inlet of the finned tube of the switching condenser 12; the second oil pump 15 is used to pump the circulating hot oil in the hot oil tank 14 into the steam heater 17 for heating, and then send it to the finned tube of the switching condenser 12 after being heated to a preset temperature.

[0027] The oil replenishment system at least includes an oil storage tank 3, an expansion tank 4 and an electric heater 7. Among them, the expansion tank 4 has at least a first liquid inlet, a liquid phase outlet and a gas phase outlet. The first liquid inlet of the expansion tank 4 is connected to the outlet of the oil storage tank 3, the liquid phase outlet of the expansion tank 4 is connected to the oil inlet of the electric heater 7 through the third oil pump 6, and the gas phase outlet of the expansion tank 4 is connected to the outside, through which the oil in the expansion tank 4 can be dehydrated and exhausted.

[0028] Among them, the start-up of the electric heater 7 must ensure that the spare oil in the expansion tank 4 is above the 1 / 4 liquid level. The electric heater 7 can effectively improve the dehydration and degassing of the hot oil during the start-up process, stabilize the system hot oil circulation temperature, speed up the production progress, reduce energy consumption, and save energy.

[0029] Generally, the switch condenser 12 generally includes a shell, finned tubes and a shell side arranged in the shell, and the interior of the finned tubes forms a tube side. Hot phthalic anhydride gas is usually introduced into the shell side, and the shell side is used to communicate with the cold oil system and the hot oil system respectively. As for the specific structure of the switch condenser 12, it belongs to the prior art and will not be described in detail in this embodiment.

[0030] When producing crude phthalic anhydride products, phthalic anhydride gas can be introduced into the shell side of the switching condenser 12, and then circulating cold oil can be pumped into the tube side of the switching condenser 12 through the cold oil system. When the hot phthalic anhydride gas passes through the fin tubes through which the circulating cold oil is introduced, it will condense on the outer peripheral wall of the fin tubes to obtain solid phthalic anhydride. Finally, circulating hot oil is pumped into the tube side of the switching condenser 12 through the hot oil system, so that the solid phthalic anhydride originally condensed on the outer peripheral wall of the fin tube begins to melt and is discharged to the crude phthalic anhydride intermediate tank through the discharge pipeline, thereby obtaining a crude phthalic anhydride product.

[0031] In the circulation system for removing gaseous impurities in phthalic anhydride of this embodiment, the circulating cold oil or circulating hot oil can be respectively supplemented into the switching condenser 12 by setting an oil supplement system. When the circulating hot oil needs to be supplemented, the electric heater 7 can be started; when the circulating cold oil needs to be supplemented, there is no need to start the electric heater 7. At the same time, the electric heater 7 in the oil supplement system can effectively improve the dehydration and degassing of the circulating hot oil during the start-up process, stabilize the circulating hot oil circulation temperature of the system, speed up the production progress, reduce energy consumption, and save energy.

[0032] In some embodiments, the outlet of the electric heater 7 is also connected to the expansion tank 4 through an exhaust pipeline, which can be used to discharge the air, water vapor and low waste of the reserve oil.

[0033] like Figure 1 As shown, the oil inlet of the oil storage tank 3 of the present embodiment is connected to the oil filling pipeline 1, through which the spare oil can be injected into the oil storage tank 3, and a fourth oil pump 2 is provided on the pipeline connecting the oil outlet of the oil storage tank 3 and the oil inlet of the expansion tank 4, through which the spare oil in the oil storage tank 3 can be pumped into the expansion tank 4 for dehydration, exhaust, volume expansion buffering, etc.

[0034] like Figure 1 As shown, in some embodiments, the circulation system further includes a first three-way liquid phase valve 11 and a second three-way liquid phase valve 13 .

[0035] The first three-way liquid phase valve 11 is used to connect the inlet of the finned tube of the switch condenser 12, the oil outlet of the cooler 10, and the oil outlet of the steam heater 17. The second three-way liquid phase valve 13 is used to connect the outlet of the finned tube of the switch condenser 12, the oil inlet of the cold oil tank 8, and the oil inlet of the hot oil tank 14.

[0036] When it is necessary to pump circulating cold oil into the switch condenser 12, the valve port of the first three-way liquid phase valve 11 connected to the steam heater can be closed, and the valve port of the second three-way liquid phase valve 13 connected to the oil inlet of the hot oil tank 14 can be closed at the same time;

[0037] When circulating hot oil needs to be pumped into the switching condenser 12, the valve port of the first three-way liquid phase valve 11 connected to the cooler 10 can be closed, and the valve port of the second three-way liquid phase valve 13 connected to the oil inlet of the cold oil tank 8 can be closed.

[0038] The cold oil circulation system and the hot oil circulation system can be effectively switched through two three-way liquid phase valves, and the operation is simple and reliable.

[0039] In some embodiments, an oil-gas separator 5 is provided on the pipeline connecting the liquid phase outlet of the expansion tank 4 in the circulation system with the oil inlet of the third oil pump 6, and the water vapor in the standby oil can be separated from the circulation system through the oil-gas separator 5.

[0040] like Figure 1 As shown, the steam heater 17 of this embodiment is connected to a medium-pressure steam pipeline 18, and medium-pressure steam is input into the steam heater 17 through the medium-pressure steam pipeline 18. The steam heater 17 is heated by medium-pressure steam, which can effectively ensure the hot oil temperature, eliminate the heat storage oil tank 14 of the traditional process, reduce energy consumption, and save energy.

[0041] In some embodiments, a temperature control system may be provided on the medium-pressure steam pipeline 18 of the present embodiment, through which the temperature control system shell can adjust the temperature of the medium-pressure steam, thereby automatically adjusting the temperature in the oil outlet pipeline of the steam heater 17, thereby realizing automatic temperature control of the circulating hot oil, thereby avoiding problems such as rapid corrosion of the switching condenser 12 caused by excessively high circulating hot oil temperature, and reduced efficiency of the switching condenser 12 caused by excessively low circulating hot oil temperature.

[0042] Furthermore, the cooler 10 of this embodiment cools the cold oil by circulating water, and a circulating water pipeline (not shown in the figure) is provided on the cooler 10.

[0043] In some embodiments, a temperature control system may also be provided for the circulating water pipeline. The temperature of the circulating water can be adjusted by the temperature control system, thereby automatically adjusting the temperature of the circulating water in the cooler 10, thereby achieving the temperature in the oil outlet pipeline of the cooler 10, thereby avoiding problems such as reduced efficiency of the switching condenser 12 due to excessively high cooling oil temperature, and acid corrosion and reduced product quality due to excessively low cooling oil temperature.

[0044] In some embodiments, the oil storage tank 3 and the expansion tank 4 are respectively provided with a level gauge for detecting the oil level, so that the amount of spare oil added to the system can be conveniently controlled. The cold oil tank 8 and the hot oil tank 14 are also respectively provided with a level gauge, so as to facilitate the observation of the amount of circulating cold oil and circulating hot oil in the circulation system.

[0045] In some embodiments, the cold oil tank 8 and the hot oil tank 14 are respectively connected to the first nitrogen pipeline 19, and the expansion tank 4 is connected to the second nitrogen pipeline 20. The nitrogen system is respectively connected to the first nitrogen pipeline 19 and the second nitrogen pipeline 20 to respectively input nitrogen into the cold oil tank 8, the hot oil tank 14 and the expansion tank 4, thereby achieving nitrogen sealing.

[0046] like Figure 1 As shown, the oil outlet of the second oil pump 15 of this embodiment is also connected to the hot oil tank 14 through an oil return pipeline, wherein an oil filter 16 is provided on the oil return pipeline, and the excess hot oil pumped out by the second oil pump 15 can be returned to the hot oil tank 14 through the oil return pipeline, and the oil filter 16 can remove fixed impurities in the hot oil.

[0047] The embodiment of the utility model further provides a phthalic anhydride production system, which comprises the circulation system for removing gas phase impurities in phthalic anhydride as described in any one of the above embodiments.

[0048] The above description is intended to be illustrative rather than restrictive, and those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure. Moreover, the above examples (or one or more of them) may be used in combination with each other, and it is contemplated that these embodiments may be combined with each other in various combinations or permutations.

Claims

1. A circulation system for removing gaseous impurities from phthalic anhydride, comprising a switching condenser, characterized in that: The circulatory system further comprises: A cold oil system, comprising a cold oil tank and a cooler, wherein the oil outlet of the cold oil tank is connected to the oil inlet of the cooler through a first oil pump, and the oil outlet of the cooler is connected to the inlet of the fin tube of the switch condenser; A hot oil system, comprising a hot oil tank and a steam heater, wherein the oil outlet of the hot oil tank is connected to the oil inlet of the steam heater via a second oil pump, and the oil outlet of the steam heater is connected to the inlet of the finned tube of the switch condenser; The oil replenishment system at least includes an oil storage tank, an expansion tank and an electric heater, wherein the expansion tank has at least a first liquid inlet, a liquid phase outlet and a gas phase outlet, the first liquid inlet is connected to the outlet of the oil storage tank, the liquid phase outlet is connected to the oil inlet of the electric heater through a third oil pump, the gas phase outlet is connected to the outside, and the oil outlet of the electric heater is connected to the inlet of the fin tube of the switching condenser.

2. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: The circulation system also includes a first three-way liquid-phase valve and a second three-way liquid-phase valve, wherein the first three-way liquid-phase valve is used to connect the inlet of the fin tube of the switching condenser, the oil outlet of the cooler and the oil outlet of the steam heater, and the second three-way liquid-phase valve is used to connect the outlet of the fin tube of the switching condenser, the oil inlet of the cold oil tank and the oil inlet of the hot oil tank.

3. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: An oil-gas separator is provided on a pipeline connecting the liquid phase outlet of the expansion tank and the oil inlet of the third oil pump.

4. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: The oil storage tank, the expansion tank, the cold oil tank and the hot oil tank are respectively provided with a liquid level gauge for detecting the height of the internal liquid.

5. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: The circulation system also includes a nitrogen system. Nitrogen pipelines are respectively connected to the cold oil tank, the hot oil tank and the expansion tank, and the nitrogen system is in communication with the nitrogen pipelines.

6. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: The expansion tank is also provided with a second liquid inlet, and the oil outlet of the first oil pump is also connected to the second liquid inlet.

7. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: The oil outlet of the second oil pump is communicated with the hot oil tank through an oil return pipeline, and an oil filter is provided on the oil return pipeline.

8. The circulation system for removing gas phase impurities in phthalic anhydride according to claim 1, characterized in that: The oil inlet of the oil storage tank is connected to the oil filling pipeline, and the oil outlet of the oil storage tank is connected to the oil inlet of the expansion tank through a fourth oil pump.

9. A phthalic anhydride production system, characterized in that: A circulation system for removing gas phase impurities in phthalic anhydride comprising the circulation system described in any one of claims 1 to 8.

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