Tower top waste heat recovery system for toluene

Abstract

The utility model belongs to the field of chemical engineering, and particularly relates to a toluene tower top waste heat recovery system which comprises a toluene tower and a toluene tower return tank, a toluene tower top gas phase outlet is connected to a toluene tower air cooler through a first gas phase branch line, and a toluene tower air cooler outlet is connected to the toluene tower return tank through a return tank inlet pipeline. The first gas phase branch line is connected to an inlet of the first heat exchanger through a heat exchanger inlet pipeline, and a gas phase cooled by the first heat exchanger is connected to a return tank inlet pipeline through a corresponding first heat exchanger outlet and a heat exchanger outlet pipeline; a flow control regulating valve group is arranged on an outlet pipeline of the heat exchanger, and the first heat exchanger is arranged on a feeding pipeline of the disproportionation stabilizing tower and is used for preheating fed materials of the disproportionation stabilizing tower. According to the utility model, materials from the top of a toluene tower to an air cooling part are subjected to heat exchange with the newly added heat exchanger on the feed line of the disproportionation stabilization tower, so that the effect of recovering gas-phase waste heat is achieved.

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry, and specifically relates to a toluene tower top waste heat recovery system. Background Art

[0002] The gaseous components at the top of the toluene tower need to be cooled to the required temperature before entering the reflux tank of the toluene tower. Because the materials passing through the air-cooling part need to be cooled by an air cooler, the temperature difference before and after air cooling is nearly 30°C, resulting in power consumption and energy waste. Summary of the invention

[0003] In view of the defects of the above-mentioned prior art, the purpose of the utility model is to provide a toluene tower top waste heat recovery system and a recovery method thereof, the waste heat from the gas phase to the air-cooling part of the toluene tower is recovered and controlled, and the materials from the top of the toluene tower to the air-cooling part are heat exchanged with the heat exchanger on the feed line of the disproportionation stabilization tower through a pipeline, so as to achieve the purpose of heat recovery and saving energy consumption.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a toluene tower top waste heat recovery system, including a toluene tower and a toluene tower reflux tank, the toluene tower top gas phase outlet is connected to the toluene tower air cooler through a first gas phase branch line, the toluene tower air cooler outlet is connected to the toluene tower reflux tank through a reflux tank inlet pipeline, the first gas phase branch line is connected to the inlet of the first heat exchanger through a heat exchanger inlet pipe, the gas phase cooled by the first heat exchanger is connected to the reflux tank inlet pipeline through the corresponding first heat exchanger outlet through the heat exchanger outlet pipe; a flow control regulating valve group is arranged on the heat exchanger outlet pipeline, and the first heat exchanger is arranged on the feed pipeline of the disproportionation stabilization tower to preheat the feed of the disproportionation stabilization tower.

[0005] Furthermore, a bypass pipeline is provided between the inlet and outlet of the first heat exchanger on the feed pipeline of the disproportionation stabilization tower, and a temperature control regulating valve group is provided on the bypass pipeline. A bypass pipeline is provided for the first heat exchanger on the feed pipeline of the disproportionation stabilization tower, and a temperature control regulating valve group is provided on the bypass pipeline. It is used to control the heat exchange amount of the first heat exchanger.

[0006] Furthermore, the feed pipeline of the disproportionation stabilizer is connected from the disproportionation product separation tank to the inlet of the disproportionation stabilizer, and a feed heat exchanger group is arranged on the feed pipeline of the disproportionation stabilizer. The first heat exchanger is arranged in front of the feed heat exchanger group to preheat the feed of the feed heat exchanger group.

[0007] Furthermore, the heat exchanger group includes two disproportionation feed / product separation tank bottom heat exchangers arranged in series and two disproportionation stabilization tower feed / tower bottom heat exchangers arranged in series.

[0008] Furthermore, two disproportionate feed / product separation tank bottom heat exchangers are connected to the shell side of the disproportionate stabilization tower feed pipeline, and the tube sides of the two disproportionate feed / product separation tank bottom heat exchangers are fed by the disproportionate reaction feed pump and discharged to the disproportionate feed / product heat exchanger.

[0009] Furthermore, two disproportionation stabilizer feed / bottom heat exchangers are connected to the shell side of the disproportionation stabilizer feed pipeline, and the tube sides of the two disproportionation feed / product separation tank bottom heat exchangers are fed from the disproportionation stabilizer bottom pump and discharged to the disproportionation clay processor feed / discharge heat exchanger.

[0010] Furthermore, the heat exchanger inlet pipe and the heat exchanger outlet pipe are connected to the tube side of the first heat exchanger, and the feed pipeline of the disproportionation stabilization tower is connected to the shell side of the first heat exchanger.

[0011] Furthermore, a temperature control remote transmitter is provided on the outlet pipe of the heat exchanger.

[0012] Furthermore, the heat exchanger inlet pipe is provided with an inlet pipe isolation first valve and an inlet pipe isolation second valve at the inlet, and an inlet pipe drainage valve is provided between the inlet pipe isolation first valve and the inlet pipe isolation second valve.

[0013] Furthermore, an outlet pipe guide valve and an outlet pipe isolation valve are sequentially arranged at the outlet of the heat exchanger outlet pipe.

[0014] Furthermore, a first shower valve and a first valve are sequentially arranged on the inlet pipeline of the reflux tank, and the first valve is located in front of the outlet of the heat exchanger outlet pipeline.

[0015] Furthermore, the gas phase outlet at the top of the toluene tower is connected to the bottom reboiler of the benzene tower through a second gas phase branch line to supply heat to the bottom reboiler of the benzene tower, and the gas phase after heat exchange is connected to the toluene tower reflux tank from the bottom reboiler outlet of the benzene tower.

[0016] A recovery method for a toluene tower top waste heat recovery system, wherein a portion of the toluene tower top gas phase enters the benzene tower bottom reboiler through a second gas phase branch line, provides heat for the benzene tower bottom reboiler and then enters the toluene tower reflux tank, and another portion of the toluene tower top gas phase enters a first gas phase pipeline. Under normal operating conditions, all the gas phases in the first gas phase pipeline are heat exchanged through a first heat exchanger. If the outlet temperature of the first heat exchanger is lower than a predetermined value, the flow rate of cold materials entering the first heat exchanger is adjusted by a temperature control regulating valve group.

[0017] Furthermore, the gas phase entering the first gas phase branch line from the top of the toluene tower passes through the first heat exchanger to heat the feed of the disproportionation stabilization tower and then enters the reflux tank of the toluene tower; the gas phase flow is controlled by the flow control regulating valve group, and the outlet temperature of the first heat exchanger is measured and uploaded by the temperature control remote transmitter; when the first heat exchanger is put into use, the inlet pipeline isolation first valve, the inlet pipeline isolation second valve, and the outlet pipeline isolation valve are opened, and the gas phase in the first gas phase branch line passes through the heat exchanger inlet pipeline and the heat exchanger outlet pipeline and is cooled by the first heat exchanger; the first valve is closed, and the heat exchange of the first heat exchanger is controlled by adjusting the first heat exchanger bypass regulating valve to control the outlet temperature of the first heat exchanger to the required temperature. If the first heat exchanger bypass valve is fully closed and the outlet temperature is still higher than the predetermined temperature, the first valve is opened, and part of the gas phase in the first gas phase branch line passes through the reflux tank inlet pipeline and is cooled by the toluene tower air cooler, and the other part passes through the heat exchanger inlet pipeline and the heat exchanger outlet pipeline and is cooled by the first heat exchanger.

[0018] The beneficial effects of the utility model are as follows: the utility model adds a heat exchanger on the feed line of the disproportionation stabilization tower, and the material from the top of the toluene tower to the air-cooled part is heat-exchanged with the newly added heat exchanger on the feed line of the disproportionation stabilization tower through a pipeline, and the material after heat exchange is returned to the reflux tank of the toluene tower after the flow and temperature are controlled by the newly added regulating valve group. The effect of recovering gas phase waste heat is achieved, and at the same time, the power of the toluene tower air cooler, the amount of reboiled steam at the bottom of the disproportionation stabilization tower, and the temperature of the feed line of the disproportionation stabilization tower are saved, and the purpose of saving back-end energy consumption is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a process flow chart of the toluene tower top waste heat recovery system of the utility model;

[0020] Figure 2 It is a schematic diagram of the connection between the toluene tower and the benzene tower;

[0021] In the figure: 1, toluene tower, 2, toluene tower reflux tank, 3, first gas phase branch line, 4, toluene tower air cooler, 5, reflux tank inlet pipeline, 6, heat exchanger inlet pipeline, 7, first heat exchanger, 8, heat exchanger outlet pipeline, 9, flow control regulating valve group, 10, disproportionation stabilization tower feed pipeline, 11, disproportionation stabilization tower, 12, temperature control remote transmitter, 13, inlet pipeline isolation first valve, 14, inlet pipeline isolation second valve, 15, inlet pipeline drain valve, 16, outlet pipeline drain valve, 17, outlet pipeline isolation valve, 18, first drain valve, 19, first valve, 20, second gas phase branch line, 21, benzene tower bottom reboiler, 22, temperature control regulating valve group, 23, disproportionation feed / product separation tank bottom heat exchanger, 24, disproportionation stabilization tower feed / tower bottom heat exchanger. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0023] See attached Figure 1-2 , a toluene tower top waste heat recovery system, comprising a toluene tower 1 and a toluene tower reflux tank 2, wherein the toluene tower top gas phase outlet is connected to a toluene tower air cooler 4 through a first gas phase branch line 3, and the toluene tower air cooler 4 outlet is connected to the toluene tower reflux tank 2 through a reflux tank inlet pipeline 5, and the first gas phase branch line 3 is connected to the inlet of a first heat exchanger 7 through a heat exchanger inlet pipeline 6, and the gas phase cooled by the first heat exchanger 7 is connected to the reflux tank inlet pipeline 5 through a heat exchanger outlet pipeline 8 through the corresponding first heat exchanger outlet; the heat exchanger outlet pipe A flow control regulating valve group 9 is arranged on the channel 8, the first heat exchanger 7 is arranged on the feed pipeline 10 of the disproportionation stabilization tower to preheat the feed of the disproportionation stabilization tower 11, a bypass pipeline is arranged on the feed pipeline 10 of the disproportionation stabilization tower for the first heat exchanger 7, and a temperature control regulating valve group 22 is arranged on the bypass pipeline. Under normal working conditions, the remaining gas phase of the toluene tower in the first gas phase branch line 3 is all heat exchanged through the first heat exchanger 7. If the return oil temperature is lower than the control value, the flow rate of the cold material entering the first heat exchanger 7 can be adjusted by adjusting the valve group 22 for regulation.

[0024] Furthermore, the feed pipeline 10 of the disproportionation stabilizer is connected from the disproportionation product separation tank to the inlet of the disproportionation stabilizer 11, and a feed heat exchanger group is arranged on the feed pipeline 10 of the disproportionation stabilizer. The first heat exchanger 7 is arranged in front of the feed heat exchanger group to preheat the feed of the feed heat exchanger group.

[0025] Furthermore, the heat exchanger group includes two disproportionation feed / product separation tank bottom heat exchangers 23 arranged in series and two disproportionation stabilization tower feed / tower bottom heat exchangers 24 arranged in series.

[0026] Furthermore, two disproportionate feed / product separation tank bottom heat exchangers 23 are connected to the shell side of the disproportionate stabilization tower feed pipeline 10, and the tube sides of the two disproportionate feed / product separation tank bottom heat exchangers 23 are fed from the disproportionate reaction feed pump and discharged to the disproportionate feed / product heat exchanger.

[0027] Furthermore, two disproportionation stabilizer feed / bottom heat exchangers 24 are connected to the shell side of the disproportionation stabilizer feed pipeline 10, and the tube sides of the two disproportionation feed / product separation tank bottom heat exchangers 24 are fed from the disproportionation stabilizer bottom pump and discharged to the disproportionation clay processor feed / discharge heat exchanger.

[0028] Furthermore, the heat exchanger inlet pipe 6 and the heat exchanger outlet pipe 8 are connected to the tube side of the first heat exchanger 7 , and the feed pipeline 10 of the disproportionation stabilization tower is connected to the shell side of the first heat exchanger 7 .

[0029] Furthermore, a temperature control remote transmitter 12 is provided on the heat exchanger outlet pipe 8 .

[0030] Furthermore, the heat exchanger inlet pipe 6 is provided with an inlet pipe isolation first valve and an inlet pipe isolation second valve at the inlet, and an inlet pipe drainage valve 15 is provided between the inlet pipe isolation first valve 13 and the inlet pipe isolation second valve 14.

[0031] Furthermore, the heat exchanger outlet pipe 8 is provided with an outlet pipe guide valve 16 and an outlet pipe isolation valve 17 in sequence at the outlet.

[0032] Furthermore, a first shower valve 18 and a first valve 19 are sequentially arranged on the reflux tank inlet pipeline 5 , and the first valve 19 is located in front of the outlet of the heat exchanger outlet pipeline 8 .

[0033] Furthermore, the gas phase outlet at the top of the toluene tower is connected to the benzene tower bottom reboiler 21 through the second gas phase branch line 20 to provide heat for the benzene tower bottom reboiler 21, and the gas phase after heat exchange is connected to the toluene tower reflux tank 2 from the outlet of the benzene tower bottom reboiler 21.

[0034] A recovery method for a toluene tower top waste heat recovery system, wherein a portion of the toluene tower top gas phase passes through a benzene tower bottom reboiler 21, provides heat for the benzene tower bottom reboiler, and then enters a toluene tower reflux tank 2, and another portion of the toluene tower top gas phase passes through a first heat exchanger 7 to provide heat for the feed of a disproportionation stabilization tower and then enters a toluene tower reflux tank 2; the flow rate is controlled by a flow control regulating valve group 9, and the outlet temperature of the first heat exchanger 7 is measured and uploaded by a temperature control remote transmitter 12.

[0035] When put into use, open the first inlet pipeline isolation valve 13, the second inlet pipeline isolation valve 14, and the outlet pipeline isolation valve 17, and the gas phase in the first gas phase branch line passes through the heat exchanger inlet pipeline 6 and the heat exchanger outlet pipeline 8, and is cooled by the first heat exchanger 7; slowly close the first valve 19, and adjust the first heat exchanger bypass regulating valve 22 to control the heat exchange of the first heat exchanger 7 and then control the outlet temperature 12 of the first heat exchanger 7 to reach the required temperature. If the bypass valve 22 of the first heat exchanger 7 is fully closed, and the outlet temperature 12 is still higher than the predetermined temperature, adjust the opening of the first valve 19, and a part of the gas phase in the first gas phase branch line passes through the toluene tower air cooler inlet pipeline 3, and is cooled by the toluene tower air cooler 4, and the other part passes through the heat exchanger inlet pipeline 6 and the heat exchanger outlet pipeline 8, and is cooled by the first heat exchanger 7.

[0036] The pipeline transformation process of the toluene tower top waste heat recovery system of the utility model is as follows:

[0037] 1. Add the first heat exchanger 7, reconstruct the pipeline from the D505 disproportionation product separation tank liquid phase discharge pipeline FV5041 valve to the shell side inlet pipeline of the disproportionation feed / product separation tank bottom heat exchanger, add the first heat exchanger 7 shell side inlet configuration pipeline after the FV5041 valve, and add the first heat exchanger 7 shell side outlet to the disproportionation feed / product separation tank bottom heat exchanger configuration pipeline. A bypass pipeline is configured for the first heat exchanger 7 between the D505 disproportionation product separation tank liquid phase discharge pipeline FV5041 valve and the shell side inlet pipeline of the disproportionation feed / product separation tank bottom heat exchanger, and a temperature control regulating valve group 22 is set. The temperature control regulating valve group 22 includes (temperature control valve, regulating valve front gate valve, regulating valve rear gate valve, regulating valve bypass stop valve, and a maintenance pressure relief valve group set between the regulating valve and the front gate valve for discharge to the underground tank and on-site open discharge, etc.).

[0038] 2. Add a new heat exchanger inlet pipe 6, which is configured from the top of the toluene tower to the PV5027 valve and connected to the inlet of the first heat exchanger 7 pipe. An inlet pipe guide valve 15 is provided between the newly added inlet pipe isolation first valve 13 and the inlet pipe isolation second valve 14 near PV5027 of the newly added heat exchanger inlet pipe 6.

[0039] 3. Add a new heat exchanger outlet pipeline 8, configure a pipeline from the outlet of the first heat exchanger 7 pipe pass, and connect it to the inlet pipeline 5 of the toluene tower reflux tank. Set a temperature remote transmission 12 on the new pipeline 8. Set a flow control regulating valve group 9 to control the heat exchange flow of the newly added first heat exchanger 7. The flow control regulating valve group 9 includes (flow control valve, gate valve before regulating valve, gate valve after regulating valve, regulating valve bypass stop valve, and matching flow orifice plate, and a maintenance pressure relief valve group set between the regulating valve and the front gate valve to discharge to the underground tank and on-site open discharge).

[0040] 4. Add an outlet pipeline isolation valve 17 before the meeting point between the outlet pipeline 8 of the heat exchanger and the inlet pipeline 5 of the reflux tank, and add an outlet pipeline drainage valve 16 before the outlet pipeline isolation valve 17.

[0041] 5. Add a first valve 19 to the reflux tank inlet pipeline 5 from the toluene tower air cooler 4 to the toluene tower reflux tank 2, and add a first drain valve 18 from the toluene tower air cooler 4 to the newly added first valve 19. (It should be noted that the first valve 19 should be located before the three-way connection at the meeting point of the newly added heat exchanger outlet pipeline 8 and the original reflux tank inlet pipeline 5, and the distance between the first valve 19 and the outlet pipeline isolation valve 17 and the three-way connection should not be too far).

[0042] Compared with the original pipeline, the beneficial effects of the modified pipeline are:

[0043] 1. The top of the toluene tower is connected to the newly added first heat exchanger 7 through the heat exchanger inlet pipe 6, and heat is exchanged through the first heat exchanger 7 to increase the feed temperature of the disproportionation stabilization tower, thereby saving the amount of reboiled steam in the disproportionation stabilization tower.

[0044] 2. After adding the first heat exchanger 7, the air cooling heat load of the toluene tower air cooler 4 will be reduced, saving air cooling electricity. By adjusting the opening of the temperature control valve 22, the temperature control point 12 after heat exchange of the first heat exchanger 7 can be controlled to be close to the original material temperature of the toluene tower reflux tank 2. Under normal working conditions, the toluene tower air cooler 5 can be completely disabled.

[0045] 3. After the modification of the newly added first heat exchanger 7, the feed temperature of the cold logistics of the original feed heat exchangers 23 and 24 of the disproportionation stabilization tower increases, which saves heat consumption accordingly, and the outlet temperature of the pipes 23 and 24 increases accordingly, saving energy consumption in the back-end.

[0046] Under normal conditions, the gas phase at the top of the toluene tower provides a heat source for the benzene tower through the reboiler 21 at the bottom of the benzene tower. After heat exchange, the flow rate and temperature are controlled by the flow control valve FV5012 to return to the reflux tank 2 of the toluene tower. The remaining gas phase is cooled to the required temperature by the toluene tower air cooler 4 and then enters the reflux tank 2 of the toluene tower. After the transformation, the remaining gas phase at the top of the toluene tower is heat exchanged through the newly added first heat exchanger 7 to increase the feed temperature of the disproportionation stabilization tower. Through the newly added flow control regulating valve group 9, the newly added temperature control regulating valve group 22 and the newly added temperature control point 12, the gas phase flow through the newly added heat exchanger and the cold material flow through the first heat exchanger 7 are controlled to stabilize the return oil temperature, and the toluene tower pressure is controlled by PV5027. New isolation valves are added to the heat exchanger inlet pipe 6, the heat exchanger outlet pipe 8 and the reflux tank inlet pipeline 5 for switching and isolating the heat exchanger and air cooling.

[0047] The present invention does not disclose some common knowledge in the art.

[0048] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0049] The above examples are only the best embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and there are many variations. All variations that can be directly derived or associated with the contents disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A toluene tower top waste heat recovery system, Features: It includes a toluene tower and a toluene tower reflux tank, wherein the toluene tower top gas phase outlet is connected to the toluene tower air cooler through a first gas phase branch line, the toluene tower air cooler outlet is connected to the toluene tower reflux tank through a reflux tank inlet pipeline, the first gas phase branch line is connected to the inlet of the first heat exchanger through a heat exchanger inlet pipeline, the gas phase cooled by the first heat exchanger is connected to the reflux tank inlet pipeline through the corresponding first heat exchanger outlet through a heat exchanger outlet pipeline; a flow control regulating valve group is arranged on the heat exchanger outlet pipeline, and the first heat exchanger is arranged on the feed pipeline of the disproportionation stabilization tower to preheat the feed of the disproportionation stabilization tower.

2. A toluene tower top waste heat recovery system according to claim 1, Features: A bypass pipeline is arranged between the inlet and outlet of the first heat exchanger on the feed pipeline of the disproportionation stabilization tower, and a temperature control regulating valve group is arranged on the bypass pipeline.

3. A toluene tower top waste heat recovery system according to claim 1, Features: The feed pipeline of the disproportionation stabilization tower is connected from the disproportionation product separation tank to the inlet of the disproportionation stabilization tower. A feed heat exchanger group is arranged on the feed pipeline of the disproportionation stabilization tower. The first heat exchanger is arranged in front of the feed heat exchanger group to preheat the feed of the feed heat exchanger group.

4. A toluene tower top waste heat recovery system according to claim 1, Features: The heat exchanger inlet pipe and the heat exchanger outlet pipe are connected to the tube side of the first heat exchanger, and the feed pipeline of the disproportionation stabilization tower is connected to the shell side of the first heat exchanger.

5. A toluene tower top waste heat recovery system according to claim 1, Features: A temperature control remote transmitter is arranged on the outlet pipe of the heat exchanger.

6. A toluene tower top waste heat recovery system according to claim 1, Features: The heat exchanger inlet pipe is provided with an inlet pipe isolation first valve and an inlet pipe isolation second valve at the inlet, and an inlet pipe drainage valve is provided between the inlet pipe isolation first valve and the inlet pipe isolation second valve.

7. A toluene tower top waste heat recovery system according to claim 1, Features: The outlet pipe of the heat exchanger is provided with an outlet pipe guide valve and an outlet pipe isolation valve in sequence at the outlet.

8. A toluene tower top waste heat recovery system according to claim 1, Features: The first shower valve and the first valve are sequentially arranged on the inlet pipeline of the reflux tank, and the first valve is located in front of the outlet of the heat exchanger outlet pipeline.

Images