Phthalic anhydride tail gas waste heat recycling system

Abstract

The utility model provides a phthalic anhydride tail gas waste heat recycling system which comprises a catalytic oxidation tail gas emission system which comprises a plurality of tail gas outlet pipelines connected with different tail gas outlets of a catalytic oxidation system; the steam generation system is connected with the tail gas outlet pipelines and used for evaporating desalted water into steam by using waste heat of the tail gas discharged by the tail gas outlet pipelines as a heat source; the adjusting and switching system is arranged on the tail gas outlet pipelines and used for enabling the tail gas to selectively enter different tail gas outlet pipelines and selectively and directly discharge or enter the steam generation system; and the high-temperature condensate water collecting system is connected with the steam generating system and is used for collecting and recycling the high-temperature condensate water generated by the steam generating system. According to changes of production loads and operation conditions, exhaust gas emission paths can be flexibly switched, waste heat in the exhaust gas is effectively recycled, and maximum utilization of the exhaust gas is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of naphthalene phthalic anhydride production, and particularly relates to a phthalic anhydride tail gas waste heat recycling system. BACKGROUND

[0002] At present, in the traditional production process of industrial naphthalene phthalic anhydride, phthalic anhydride (referred to as phthalic anhydride) tail gas separated from a hot melting tank enters a tail gas treatment device for further treatment. In the phthalic anhydride tail gas catalytic oxidation treatment process, the organic matter contained in the phthalic anhydride tail gas is fully reacted into CO2 and H2O and the like under the action of a catalyst, and the gas after reaction is as high as about 420 DEG C. The high-temperature gas is heat-exchanged with the preheated tail gas through a heat exchanger, is cooled to about 220 DEG C, and is discharged into a chimney through a four-way valve, thereby causing heat loss and waste. CONTENT OF THE UTILITY MODEL

[0003] In view of the above technical problems existing in the prior art, the application embodiment provides a phthalic anhydride tail gas waste heat recycling system, which effectively recycles the waste heat in the tail gas and realizes the maximum utilization of energy.

[0004] The technical scheme adopted by the application embodiment is as follows: a phthalic anhydride tail gas waste heat recycling system, comprising:

[0005] A catalytic oxidation tail gas discharge system, comprising a plurality of tail gas outlet pipelines connected with different tail gas outlets of a catalytic oxidation system;

[0006] A steam generation system connected with the plurality of tail gas outlet pipelines, for evaporating desalted water to form steam by using the waste heat of the tail gas discharged from the plurality of tail gas outlet pipelines as a heat source;

[0007] An adjusting and switching system arranged on the plurality of tail gas outlet pipelines, for switching the discharge paths of the tail gas in the plurality of tail gas outlet pipelines respectively, so that the tail gas selectively enters different tail gas outlet pipelines and is selectively directly discharged or enters the steam generation system;

[0008] A high-temperature condensed water collection system connected with the steam generation system, for collecting and recycling the high-temperature condensed water generated by the steam generation system.

[0009] In an optional embodiment, the catalytic oxidation system comprises a first tail gas outlet and a second tail gas outlet; the catalytic oxidation tail gas discharge system comprises a first tail gas outlet pipeline and a second tail gas outlet pipeline; one end of the first tail gas outlet pipeline is connected with the first tail gas outlet, and one end of the first tail gas outlet pipeline is connected with the steam generation system; one end of the second tail gas outlet pipeline is connected with the second tail gas outlet, and one end of the second tail gas outlet pipeline is connected with the steam generation system.

[0010] In an optional embodiment, a first discharge chimney pipeline for connecting with a chimney is connected on the first tail gas outlet pipeline; and a second discharge chimney pipeline for connecting with a chimney is connected on the second tail gas outlet pipeline.

[0011] In an optional embodiment, the adjustment switching system comprises a first switching valve, a second switching valve, a third switching valve and a fourth switching valve, the first switching valve is arranged on the first tail gas outlet pipeline, the second switching valve is arranged on the second tail gas outlet pipeline, the third switching valve is arranged on the first discharge chimney pipeline, and the fourth switching valve is arranged on the second discharge chimney pipeline.

[0012] In an optional embodiment, a temperature control point is arranged on the catalytic oxidation system.

[0013] The third switching valve is an electrically controlled valve.

[0014] The phthalic anhydride tail gas waste heat recovery system further comprises a controller and a detection component for detecting the temperature at the temperature control point, the controller is electrically connected with the detection component and the third switching valve respectively; the controller receives the temperature signal of the temperature control point detected by the detection component and controls the opening degree of the third switching valve.

[0015] In an optional embodiment, the steam generation system comprises a steam generator and a desalted water delivery pump; the steam generator comprises a heat exchanger and a steam drum arranged at the upper part of the heat exchanger and connected with the cold fluid side of the heat exchanger; the outlet of the desalted water delivery pump is connected with the steam drum for feeding desalted water into the steam drum; the top of the steam drum is connected with a steam pipeline for feeding the steam generated in the steam drum into a steam pipeline network; the inlet of the hot fluid side of the heat exchanger is connected with one end of the first tail gas outlet pipeline and one end of the second tail gas outlet pipeline respectively, and the outlet of the hot fluid side of the heat exchanger is connected with the atmosphere.

[0016] In an optional embodiment, a first automatic adjusting valve is arranged on the steam pipeline for automatically adjusting the opening degree according to the steam pressure of the pipeline downstream thereof; and / or

[0017] A second automatic adjusting valve is arranged on the desalted water delivery pump.

[0018] In an optional embodiment, the high-temperature condensate collecting system comprises a high-temperature condensate tank, a condensate delivery pump and a desalinated water source tank, the inlet of the high-temperature condensate tank is connected with the outlet of the cold fluid side of the heat exchanger, the outlet of the high-temperature condensate tank is connected with the inlet of the condensate delivery pump, and the outlet of the condensate delivery pump is connected with the inlet of the desalinated water source tank; the desalinated water source tank is further connected with a raw water pipeline for feeding raw water into the desalinated water source tank and a water inlet pipeline for feeding the mixed water of the high-temperature condensate and the raw water in the desalinated water source tank into a desalinated water treatment system.

[0019] In an optional embodiment, the outlet of the hot fluid side of the heat exchanger is connected with the first exhaust chimney pipeline and the second exhaust chimney pipeline respectively, so that the tail gas after heat exchange by the heat exchanger is discharged into the atmosphere by the chimney.

[0020] In an optional embodiment, the high-temperature condensate tank and the desalinated water source tank are respectively provided with a liquid level meter for detecting the internal liquid level; and / or

[0021] The steam generator, the steam pipeline and the high-temperature condensate tank are respectively provided with a measuring element for detecting the internal temperature and pressure.

[0022] Compared with the prior art, the application has the beneficial effects that the application realizes the waste heat recovery after the treatment of the tail gas of the catalytic oxidation of naphthalene phthalic anhydride, and collects and reuses the high-temperature condensate generated by the steam generation system, which not only avoids the waste of the high-temperature condensate, but also effectively improves the heating efficiency of the desalinated water, significantly reduces the energy consumption, improves the energy utilization efficiency, and further reduces the production cost.

[0023] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, rather than limiting the application.

[0024] The foregoing overview of various implementations or examples of the technology described in this application is not exhaustive or complete with respect to the full scope of the technology or all of its features. BRIEF DESCRIPTION OF DRAWINGS

[0025] In the drawings, which are not necessarily drawn to scale, like numerals can describe similar components in different views. The drawings are intended to illustrate various embodiments in accordance with the application, and are not intended to limit the application, nor is the application limited to the precise drawings. Wherever possible, like reference numerals have been used throughout the drawings to refer to like components. Such embodiments are illustrative rather than limiting, and are not intended to exhaustively describe the application or the scope of the application.

[0026] Figure 1 It is a structural schematic diagram of the phthalic anhydride tail gas waste heat recovery system of the application.

[0027] Reference signs:

[0028] 1 - catalytic oxidation system; 11 - first tail gas outlet line; 12 - second tail gas outlet line; 13 - first exhaust stack line; 14 - second exhaust stack line; 15 - tail gas inlet line;

[0029] 21 - first switching valve; 22 - second switching valve; 23 - third switching valve; 24 - fourth switching valve; 25 - first tee; 26 - second tee;

[0030] 31 - steam generator; 311 - heat exchanger; 312 - drum; 32 - desalted water delivery pump; 33 - steam line; 34 - first automatic regulating valve; 35 - second automatic regulating valve; 36 - hot fluid side outlet line; 37 - first branch; 38 - second branch; 39 - on-off valve;

[0031] 41 - high-temperature condensate tank; 42 - condensate delivery pump; 43 - desalted water make-up tank; 44 - raw water line; 45 - water inlet line. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of protection of the present application.

[0033] Unless otherwise defined, technical terms or scientific terms used in the present application shall be understood as having the same meaning as commonly understood by those of ordinary skill in the art to which the present application belongs. The terms "first", "second" and similar terms used in the present application do not denote any order, quantity or importance, but are used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are used only to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0034] In order to keep the following description of the embodiments of the present application clear and concise, the present application omits the detailed description of known functions and known components.

[0035] The embodiment of the present application provides a phthalic anhydride tail gas waste heat recycling system, which comprises a catalytic oxidation tail gas discharge system, a steam generation system, an adjusting and switching system and a high-temperature condensed water collection system. The catalytic oxidation tail gas discharge system comprises a plurality of tail gas outlet pipelines connected with different tail gas outlets of a catalytic oxidation system 1. The catalytic oxidation system 1 is also provided with a tail gas inlet connected with a tail gas inlet pipeline 15, and phthalic anhydride tail gas is sent into the catalytic oxidation system 1 through the tail gas inlet pipeline 15. Organic substances in the phthalic anhydride tail gas are fully reacted in the catalytic oxidation system 1 under the action of a catalyst, and the generated tail gas is discharged through the plurality of tail gas outlet pipelines. The steam generation system is connected with the plurality of tail gas outlet pipelines, and is used for evaporating desalted water in the steam generation system to form steam by using the waste heat of the tail gas discharged through the plurality of tail gas outlet pipelines as a heat source. The adjusting and switching system is arranged on the plurality of tail gas outlet pipelines, and is used for switching the discharge paths of the tail gas in the plurality of tail gas outlet pipelines respectively, so that the tail gas generated by the catalytic oxidation system 1 selectively enters different tail gas outlet pipelines and is selectively directly discharged or enters the steam generation system. The high-temperature condensed water collection system is connected with the steam generation system, and is used for collecting and recycling the high-temperature condensed water generated by the steam generation system.

[0036] The phthalic anhydride tail gas waste heat recycling system of the embodiment of the present application can flexibly switch the discharge paths of the tail gas according to the changes of the production load and the operating conditions of the catalytic oxidation system 1 through the plurality of tail gas outlet pipelines of the catalytic oxidation tail gas discharge system and the corresponding adjusting and switching system, so that the tail gas is maximally utilized. Moreover, the waste of the high-temperature condensed water is avoided, and the production cost is further reduced.

[0037] In some embodiments, as shown in Figure 1 The catalytic oxidation system 1 comprises a first tail gas outlet and a second tail gas outlet; the catalytic oxidation tail gas discharge system comprises a first tail gas outlet pipeline 11 and a second tail gas outlet pipeline 12; one end of the first tail gas outlet pipeline 11 is connected with the first tail gas outlet, and one end of the first tail gas outlet pipeline 11 is connected with the steam generation system; one end of the second tail gas outlet pipeline 12 is connected with the second tail gas outlet, and one end of the second tail gas outlet pipeline 12 is connected with the steam generation system. By arranging two tail gas outlets on the catalytic oxidation system 1 and cooperating with the two tail gas outlet pipelines, when the tail gas amount in the catalytic oxidation system 1 changes due to the reaction stage and the load variation of the catalytic oxidation system 1 and other factors, the tail gas can be selectively discharged through one or both of the two tail gas outlet pipelines at the same time, so that the normal operation of the catalytic oxidation system 1 is ensured.

[0038] In some embodiments, continue to combine Figure 1The first tail gas outlet pipeline 11 is connected with a first exhaust chimney pipeline 13 for connecting with a chimney; and the second tail gas outlet pipeline 12 is connected with a second exhaust chimney pipeline 14 for connecting with the chimney. By arranging the first exhaust chimney pipeline 13 and the second exhaust chimney pipeline 14, when the amount of tail gas exceeds the amount of steam generation system, the tail gas generated by the catalytic oxidation system 1 can be sent into the chimney and directly discharged through the chimney, thereby ensuring the normal operation of the catalytic oxidation system 1.

[0039] In some embodiments, the adjusting switching system further comprises Figure 1 The first switching valve 21 is arranged on the first tail gas outlet pipeline 11, the second switching valve 22 is arranged on the second tail gas outlet pipeline 12, the third switching valve 23 is arranged on the first exhaust chimney pipeline 13, and the fourth switching valve 24 is arranged on the second exhaust chimney pipeline 14. By arranging multiple switching valves, it is convenient to realize the adjusting switching of the tail gas and maximize the utilization of the tail gas.

[0040] Further, the catalytic oxidation system 1 is provided with a temperature control point. At least one of the third switching valve 23 and the fourth switching valve 24 is an electrically controlled valve. The adjusting switching system further comprises a controller (not shown in the figure) and a detection component (not shown in the figure) for detecting the temperature of the temperature control point, the controller is electrically connected with the detection component and the third switching valve 23 and / or the fourth switching valve 24, the controller receives the temperature signal of the temperature control point detected by the detection component, and controls the opening degree of the third switching valve 23 and / or the fourth switching valve 24. By arranging the third switching valve 23 and / or the fourth switching valve 24 as an electrically controlled valve, and combining the controller and the detection component, the opening degree of the third switching valve 23 and / or the fourth switching valve 24 can be automatically adjusted according to the temperature of the catalytic oxidation system 1, so that when the temperature of the catalytic oxidation system 1 is higher than a first preset value and the amount of tail gas increases, the opening degree of the third switching valve 23 and / or the fourth switching valve 24 increases, and more tail gas is discharged from the chimney; and when the temperature of the catalytic oxidation system 1 is lower than a second preset value and the amount of tail gas decreases, the opening degree of the third switching valve 23 and / or the fourth switching valve 24 decreases or even completely closes, and a small amount of tail gas or even no tail gas is discharged from the chimney; wherein the first preset value is greater than the second preset value.

[0041] The first switch valve 21 and the second switch valve 22 can be manual valves. During the production process, the first switch valve 21 and the second switch valve 22 are both in the fully open state, so that as much tail gas generated by the catalytic oxidation system 1 as possible enters the steam generation system as a heat source to heat the desalted water to generate steam. The third switch valve 23 and the fourth switch valve 24 adjust the opening degree according to the amount of tail gas generated by the catalytic oxidation system 1, to ensure the normal operation of the catalytic oxidation system 1 and the safety of the process. Of course, when the amount of tail gas changes greatly due to the start and stop of the catalytic oxidation system 1, load variation, and operating conditions, etc., the opening degree of the first switch valve 21 and the second switch valve 22 can be manually adjusted, or even both or one of them can be closed, so that the tail gas selectively enters the steam generation system through different paths for heat exchange, and the amount of tail gas entering the heat exchanger 311 can be adjusted, to avoid the amount of tail gas entering the steam generation system exceeding the range that can be utilized, and affecting the safe operation of the entire system.

[0042] The catalytic oxidation tail gas discharge system and the adjusting and switching system of the present application are matched, to realize flexible switching and adjustment of the tail gas discharge path under the change of production load and operating conditions.

[0043] For example, the first tail gas outlet pipeline 11 can include two sections connected with the first discharge chimney pipeline 13 through a first three-way pipe 25. The two sections are a first section and a second section, the first section is close to the catalytic oxidation system 1, and the second section is close to the steam generation system, and the first switch valve 21 is arranged on the second section.

[0044] The second tail gas outlet pipeline 12 can include two sections connected with the second discharge chimney pipeline 14 through a second three-way pipe 26. The two sections are a third section and a fourth section, the third section is close to the catalytic oxidation system 1, and the fourth section is close to the steam generation system, and the second switch valve 22 is arranged on the fourth section.

[0045] In some embodiments, as Figure 1As shown, the steam generation system comprises a second three-way pipe 26 and a desalted water delivery pump 32. The second three-way pipe 26 comprises a heat exchanger 311 and a steam drum 312 arranged at the upper portion of the heat exchanger 311 and connected with the cold fluid side of the heat exchanger 311, the steam drum 312 is in communication with the cold fluid side of the heat exchanger 311 to form a heat exchange loop. The outlet of the desalted water delivery pump 32 is connected with the steam drum 312 for supplementing desalted water into the steam drum 312. The top of the steam drum 312 is connected with a steam pipeline 33, and the steam pipeline 33 is connected with a steam pipe network for sending the steam generated in the steam drum 312 into the steam pipe network to realize the delivery of the by-product steam. The hot fluid side inlet of the heat exchanger 311 is connected with one end of the first tail gas outlet pipeline 11 and one end of the second tail gas outlet pipeline 12 respectively, so that the tail gas of the catalytic oxidation system 1 is sent into the hot fluid side of the heat exchanger 311 to exchange heat with the desalted water of the cold fluid side of the heat exchanger 311, so that the desalted water is heated and evaporated into steam, and the temperature of the tail gas is correspondingly reduced. The hot fluid side outlet of the heat exchanger 311 is connected with the atmosphere to discharge the tail gas after heat exchange and temperature reduction. The steam generation system has a reasonable structure, realizes effective heat exchange between the tail gas waste heat and the desalted water, the steam generated by heat exchange is connected with the steam pipe network through the steam pipeline 33 connected with the steam outlet of the steam drum 312, and the by-production and delivery of the steam are realized. In this process, not only the waste heat in the tail gas is effectively recovered, but also the required steam for the production system is provided, and the efficient use of energy is realized.

[0046] Continuously connecting Figure 1 The end of the second section of the first tail gas outlet pipeline 11 and the end of the fourth section of the second tail gas outlet pipeline 12 are merged into one pipeline and then jointly connected to the hot fluid side inlet of the heat exchanger 311. The hot fluid side outlet of the heat exchanger 311 is connected with a hot fluid side outlet pipeline 36, and the end of the hot fluid side outlet pipeline is connected with a first branch 37 and a second branch 38 respectively, the first branch 37 is connected to the first discharge chimney pipeline 13, and the second branch 38 is connected to the second discharge chimney pipeline 14, so that the tail gas after heat exchange in the heat exchanger 311 is discharged into the atmosphere through the chimney.

[0047] Further, the first branch 37 and the second branch 38 are respectively provided with an on-off valve 39, which is a normally open valve. In the normal production process, the tail gas generated by the catalytic oxidation system 1 is cooled after heat exchange in the steam generation system, and then enters the chimney for discharge through the first branch 37 and the second branch 38 respectively; when the production is stopped or the steam generation system is not used and there is no tail gas discharge, the on-off valve 39 can be closed.

[0048] Further, as Figure 1As shown, a first automatic regulating valve 34 is installed on the steam pipeline 33. A second automatic regulating valve 35 is installed on the demineralized water transfer pump 32. The first automatic regulating valve 34 can automatically adjust its opening according to the steam pressure in the downstream steam pipeline 33. For example, when the steam pressure in the downstream steam pipeline 33 is greater than a first preset pressure range, the opening of the first automatic regulating valve 34 is reduced; when the steam pressure in the downstream steam pipeline 33 is less than a second preset pressure range, the opening of the first automatic regulating valve 34 is increased. The first preset pressure range is greater than the second preset pressure range. By setting the first automatic regulating valve 34, the steam pressure delivered to the steam network can be adjusted, and the steam level can be flexibly adjusted according to actual needs, thereby maximizing energy utilization. The second automatic regulating valve 35 can automatically adjust its opening according to the steam pressure or liquid volume in the steam drum 312, so as to replenish the corresponding amount according to the amount of demineralized water consumed in the second three-way pipe 26, so as to make the steam generation system operate in a balanced manner.

[0049] In some embodiments, such as Figure 1 As shown, the high-temperature condensate collection system includes a high-temperature condensate tank 41, a condensate transfer pump 42, and a demineralized raw water tank 43. The inlet of the high-temperature condensate tank 41 is connected to the cold fluid side outlet of the heat exchanger 311 via a high-temperature condensate pipeline, so as to collect the high-temperature condensate generated by the heat exchanger 311 into the high-temperature condensate tank 41 through the high-temperature condensate pipeline. The outlet of the high-temperature condensate tank 41 is connected to the inlet of the condensate transfer pump 42, and the outlet of the condensate transfer pump 42 is connected to the inlet of the demineralized raw water tank 43. The condensate transfer pump 42 is used to transfer the high-temperature condensate in the high-temperature condensate tank 41 to the demineralized raw water tank 43. The demineralized raw water tank 43 is also connected to a raw water pipeline 44 and an inlet water pipeline 45. The raw water pipeline 44 is used to send raw water into the demineralized raw water tank 43. The raw water and high-temperature condensate mix in the demineralized raw water tank 43 and the temperature rises. The inlet water pipeline 45 is used to send the mixed water of raw water and high-temperature condensate in the demineralized raw water tank 43 into the demineralized water treatment system.

[0050] The main function of the high-temperature condensate collection tank system is to collect and reuse the high-temperature condensate generated by the heat exchanger 311 at the bottom of the second three-way pipe 26. This design not only avoids the waste of high-temperature condensate but also effectively improves the heating efficiency of the demineralized water, further reducing production costs. The high-temperature condensate tank 41 serves not only as a temporary storage container for condensate but also monitors the condensate level in real time via a level gauge, ensuring stable system operation.

[0051] Furthermore, the high-temperature condensate tank 41 and the demineralized water tank 43 are respectively equipped with level gauges for detecting the internal liquid level, so as to monitor the liquid level in the tank in real time and ensure the safe and stable operation of the entire system.

[0052] The second three-way pipe 26, the steam pipeline 33 and the high-temperature condensate tank 41 are respectively provided with measuring elements for detecting the internal temperature and pressure. These measuring elements can respectively monitor the temperature and pressure changes inside the second three-way pipe 26, the steam pipeline 33 and the high-temperature condensate tank 41 in real time, so as to discover and handle abnormal situations in time, further improving the safety and reliability of the entire system.

[0053] The phthalic anhydride tail gas waste heat recycling system of the embodiment of the present application realizes the effective recovery of the high-temperature tail gas waste heat after the catalytic oxidation tail gas treatment by integrating the second three-way pipe 26, the high-temperature condensate collection tank and the condensate delivery pump 42 and other components. The system not only can flexibly adjust the grade of the generated steam according to the production demand, but also can significantly reduce the energy consumption and improve the energy utilization efficiency through the recycling of the high-temperature condensate. In addition, the switching valve and the measuring element arranged in the system further enhance the flexibility and safety of the system, ensuring the stability and reliability of the waste heat recovery process. In summary, the embodiment of the present application provides an efficient and practical solution for the tail gas waste heat recovery in the production of naphthalene phthalic anhydride, which helps to promote the energy saving and emission reduction and sustainable development of the related industry.

[0054] The above description is intended to be illustrative rather than restrictive, and changes, modifications, replacements and variations of the above-mentioned embodiments can be made by those skilled in the art within the scope of the present disclosure. Moreover, the above-mentioned examples (or one or more solutions thereof) can be used in combination with each other, and these embodiments can be combined with each other in various combinations or arrangements.

Claims

1. A phthalic anhydride tail gas waste heat recovery and utilization system, characterized in that, include: A catalytic oxidation exhaust gas emission system, which includes multiple exhaust gas outlet pipelines connected to different exhaust gas outlets of the catalytic oxidation system; A steam generation system, which is connected to multiple exhaust gas outlet pipelines, is used to utilize the waste heat of the exhaust gas discharged from the multiple exhaust gas outlet pipelines as a heat source to evaporate the demineralized water to form steam. The regulating and switching system is installed on multiple exhaust gas outlet pipelines and is used to switch the exhaust gas emission path in the multiple exhaust gas outlet pipelines respectively, so that the exhaust gas selectively enters different exhaust gas outlet pipelines and selectively discharges directly or enters the steam generation system. A high-temperature condensate collection system, which is connected to the steam generation system, is used to collect and reuse the high-temperature condensate generated by the steam generation system.

2. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 1, characterized in that, The catalytic oxidation system includes a first exhaust gas outlet and a second exhaust gas outlet; the catalytic oxidation exhaust gas emission system includes a first exhaust gas outlet pipeline and a second exhaust gas outlet pipeline; one end of the first exhaust gas outlet pipeline is connected to the first exhaust gas outlet, and one end of the first exhaust gas outlet pipeline is connected to the steam generation system; one end of the second exhaust gas outlet pipeline is connected to the second exhaust gas outlet, and one end of the second exhaust gas outlet pipeline is connected to the steam generation system.

3. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 2, characterized in that, The first exhaust gas outlet pipeline is connected to a first emission chimney pipeline for connection to a chimney; the second exhaust gas outlet pipeline is connected to a second emission chimney pipeline for connection to a chimney.

4. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 3, characterized in that, The regulating and switching system includes a first switching valve, a second switching valve, a third switching valve, and a fourth switching valve. The first switching valve is located on the first exhaust gas outlet pipeline, the second switching valve is located on the second exhaust gas outlet pipeline, the third switching valve is located on the first emission chimney pipeline, and the fourth switching valve is located on the second emission chimney pipeline.

5. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 4, characterized in that, The catalytic oxidation system is equipped with a temperature control point; The third switching valve is an electrically controlled valve; The adjustment and switching system also includes a controller and a detection component for detecting the temperature at the temperature control point. The controller is electrically connected to the detection component and the third switching valve respectively. The controller receives the temperature signal of the temperature control point detected by the detection component and controls the opening degree of the third switching valve.

6. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 3, characterized in that, The steam generation system includes a steam generator and a demineralized water transfer pump; the steam generator includes a heat exchanger and a steam drum located on the upper part of the heat exchanger and connected to the cold fluid side of the heat exchanger; the outlet of the demineralized water transfer pump is connected to the steam drum for feeding demineralized water into the steam drum; the top of the steam drum is connected to a steam pipeline for sending the steam generated in the steam drum into the steam pipeline network; the hot fluid side inlet of the heat exchanger is connected to one end of the first tail gas outlet pipeline and one end of the second tail gas outlet pipeline, respectively, and the hot fluid side outlet of the heat exchanger is connected to the atmosphere.

7. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 6, characterized in that, The steam pipeline is equipped with a first automatic regulating valve for automatically adjusting the opening degree according to the steam pressure of its downstream pipeline; and / or The desalination water transfer pump is equipped with a second automatic regulating valve.

8. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 6, characterized in that, The high-temperature condensate collection system includes a high-temperature condensate tank, a condensate transfer pump, and a demineralized raw water tank. The inlet of the high-temperature condensate tank is connected to the cold fluid side outlet of the heat exchanger, the outlet of the high-temperature condensate tank is connected to the inlet of the condensate transfer pump, and the outlet of the condensate transfer pump is connected to the inlet of the demineralized raw water tank. The demineralized raw water tank is also connected to a raw water pipeline for feeding raw water into the demineralized raw water tank and an inlet pipeline for feeding the water mixed with the high-temperature condensate and raw water in the demineralized raw water tank into the demineralized water treatment system.

9. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 6, characterized in that, The hot fluid side outlet of the heat exchanger is connected to the first exhaust chimney pipeline and the second exhaust chimney pipeline, respectively, so that the exhaust gas after heat exchange by the heat exchanger is discharged into the atmosphere through the chimney.

10. The phthalic anhydride tail gas waste heat recovery and utilization system according to claim 8, characterized in that, The high-temperature condensate tank and the demineralized raw water tank are each equipped with a level gauge for detecting the internal liquid level; and / or The steam generator, the steam pipeline, and the high-temperature condensate tank are each equipped with measuring elements for detecting internal temperature and pressure.

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