A self-antifreeze device for shutting down a low-temperature material distillation reboiler

Abstract

This utility model discloses a self-anti-freezing device for a low-temperature material distillation reboiler during shutdown, belonging to the field of difluoroethane production technology. It aims to solve the problem of equipment freezing and damage during maintenance caused by a sudden steam supply interruption in a low-temperature material distillation reboiler. The device includes a distillation column and a reboiler. The feed pipe of the distillation column is equipped with a feed valve; the reboiler has a steam pipe and a condensate pipe, with a steam valve on the steam pipe. The distillation column and reboiler are connected by a reboiling pipe, with a low-temperature feed valve located at any position in front of the reboiler. The device also includes a heat exchanger located between the distillation column and the reboiler, also connected by a reboiling pipe. A spare feed valve is located at any position in front of the heat exchanger on this reboiling pipe, and a discharge valve is located at any position in rear of the heat exchanger on this reboiling pipe. A steam generator is connected to the heat exchanger. This utility model has a simple structure, is easy to install, and offers significant economic benefits and safety advantages.

Description

Technical Field

[0001] This utility model belongs to the field of difluoroethane production technology, specifically relating to a self-antifreeze device for stopping a low-temperature material distillation reboiler. Background Technology

[0002] In chemical production, many materials need to be stored and transported at low temperatures, such as difluoroethane and other materials with low boiling points. These materials are typically at -5°C to -10°C before entering the distillation column and need to be heated in a reboiler before entering the distillation column to achieve distillation.

[0003] In existing technology, a reboiler is a heat exchanger installed at the bottom or side of a distillation column, its core function being to provide a continuous and stable steam flow to the column. However, in actual system operation, occasional steam supply interruptions can occur, with serious consequences. When a large amount of low-temperature material enters the reboiler and distillation column without a heat source, the situation can range from minor disruptions to production, causing the steam inside the reboiler to condense and freeze, resulting in some equipment damage; to severe cases, it can lead to the rupture of the reboiler tubes, requiring maintenance and replacement, increasing production costs. Furthermore, the material entering the reboiler and distillation column cannot be effectively collected or processed during equipment maintenance, leading to material waste and, moreover, the presence of toxic chemicals that pose occupational health hazards and environmental risks.

[0004] Based on the problems mentioned above, production personnel have proposed a self-antifreeze device for shutting down a low-temperature material distillation reboiler. Utility Model Content

[0005] The purpose of this utility model is to provide a self-antifreeze device for low-temperature material distillation reboiler shutdown, so as to solve the problem of equipment freezing and loss and material waste during maintenance when the steam supply to the low-temperature material distillation reboiler is suddenly interrupted.

[0006] To solve the above problems, the technical solution of this utility model is as follows: A self-antifreeze device for shutting down a low-temperature material distillation reboiler is disclosed. The device includes a distillation column and a reboiler. A feed valve is provided on the feed pipe of the distillation column. The reboiler is provided with a steam pipe and a condensate pipe. A steam valve is provided on the steam pipe. The distillation column and the reboiler are connected by a reboiling pipe. A low-temperature feed valve is provided at any position at the front end of the reboiler on this reboiling pipe. The device also includes a heat exchanger located between the distillation column and the reboiler. The distillation column and the heat exchanger are also connected by a reboiling pipe. A standby feed valve is provided at any position at the front end of the heat exchanger on this reboiling pipe. A discharge valve is provided at any position at the rear end of the heat exchanger on this reboiling pipe. A steam generator is connected to the heat exchanger.

[0007] Furthermore, a nitrogen pipe is installed at any position upstream of the cryogenic feed valve on the reboiler tube between the distillation column and the reboiler, and a nitrogen valve is installed on the nitrogen pipe. This is used to purge the entire material flow system after the residual material in the reboiler and its pipelines is fed into the distillation column, eliminating residual material and ensuring the safety of subsequent maintenance personnel.

[0008] Furthermore, the device also includes a central controller; a pressure transmitter is installed on the steam pipe; a temperature sensor is installed on the reboiling tube located at the rear end of the reboiler, between the distillation column and the reboiler; the input of the central controller is connected to the pressure transmitter and the temperature sensor respectively, and the output of the central controller is connected to the feed valve, cryogenic feed valve, standby feed valve, discharge valve, steam valve, and nitrogen valve respectively. The introduction of the central controller enables automated control. The pressure transmitter monitors the steam supply to the reboiler system, and the temperature sensor monitors the temperature of the material exiting the reboiler, further verifying the steam supply status. With these dual monitoring methods confirming a steam supply stoppage or steam pipeline malfunction, the central controller can immediately cut off or open the corresponding valves, ensuring that the material is switched between different pipelines for heating and ultimately smoothly enters the distillation column.

[0009] Furthermore, the heat exchanger is connected to a steam generator via an inlet pipe, which is equipped with an inlet valve. A return water pipe is also provided between the steam generator and the heat exchanger. The heat exchanger is also equipped with an outlet pipe, which is connected to a steam pipe and has a residual steam valve. Both the inlet valve and the residual steam valve are connected to the output terminal of the main controller. Steam is generated by the workshop's own steam generator, which facilitates emergency response in case of system steam supply failure. In addition to heating the materials in the heat exchanger, the generated steam will also escape and enter the reboiler to heat the materials in the reboiler, ensuring that the residual materials also enter the distillation column.

[0010] Furthermore, a reboiling valve is installed on the reboiling tube located behind the temperature sensor between the distillation column and the reboiler. The reboiling valve is also connected to the output of the main controller to facilitate the on / off control of the pipeline.

[0011] The beneficial effects of this utility model are as follows: (1) This utility model realizes the system antifreeze function when the reboiler steam supply is interrupted by heat exchanger and steam generator. By shutting down the original feed valve and steam valve of the reboiler system, the low temperature material is cut off under abnormal working conditions. At the same time, the low temperature material remaining in the reboiler and its related pipelines is heated by steam generator and heat exchanger and transported to the distillation column. In this way, not only can the low temperature material be prevented from damaging the reboiler and related pipelines in the event of a sudden interruption of the system steam supply, but the material inside the system can also be normally delivered to the distillation column. Firstly, it can reduce the maintenance cost of reboiler damage; secondly, it can recover materials and prevent waste; and thirdly, it can prevent the safety and environmental risks caused by the slow escape of the low temperature material remaining at room temperature during maintenance.

[0012] (2) This utility model has a simple structure and is easy to install. It can not only solve the problem of equipment freezing when steam supply is interrupted, but also ensure that the residual material in the reboiler enters the distillation column. Moreover, the nitrogen purging in the final stage can completely remove the residual material, ensuring the safety of workers during equipment maintenance. The economic benefits and safety effects are both outstanding. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a self-antifreeze device for shutting down a low-temperature material distillation reboiler.

[0014] The attached diagram is labeled as follows: 1-Distillation column; 2-Reboiler; 3-Main controller; 4-Heat exchanger; 5-Steam generator; G1-Feed pipe; G2-Reboiler pipe; G3-Discharge pipe; G4-Steam pipe; G5-Condensate pipe; G6-Nitrogen pipe; G7-Steam inlet pipe; G8-Return water pipe; G9-Steam outlet pipe; F1-Feed valve; F2-Cryogenic feed valve; F3-Reboiler feed valve; F4-Spare feed valve; F5-Discharge valve; F6-Steam valve; F7-Nitrogen valve; F8-Steam inlet valve; F9-Residual steam valve; T-Temperature sensor; P-Pressure transmitter. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0016] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0017] Example 1 like Figure 1 As shown, a self-antifreeze device for shutting down a low-temperature material distillation reboiler is disclosed. The device includes a distillation column 1, a reboiler 2, a main controller 3, a heat exchanger 4, and a steam generator 5.

[0018] The feed pipe G1 of the distillation column 1 is equipped with a feed valve F1, and the top of the distillation column 1 is equipped with a discharge pipe G3.

[0019] The reboiler 2 is equipped with a steam pipe G4 and a condensate pipe G5. The steam pipe G4 is equipped with a steam valve F6 and a pressure transmitter P. Distillation column 1 is connected to reboiler 2 via reboiling tube G2, which is equipped with a temperature sensor T, a low-temperature feed valve F2, and a reboiling feed valve F3. Material entering reboiler 2 passes through the low-temperature feed valve F2, and material exiting reboiler 2 passes through the temperature sensor T and the reboiling feed valve F3. Distillation column 1 is also connected to heat exchanger 4 via reboiling tube G2, which is equipped with a standby feed valve F4 and a discharge valve F5. Material entering heat exchanger 4 passes through the standby feed valve F4, and material exiting heat exchanger 4 passes through the discharge valve F5.

[0020] A nitrogen pipe G6 is installed on the reboiling pipe G2 between the distillation column 1 and the reboiler 2 at the front end of the low temperature feed valve F2, and a nitrogen valve F7 is installed on the nitrogen pipe G6.

[0021] Heat exchanger 4 and steam generator 5 are connected by steam inlet pipe G7, which is equipped with a steam inlet valve. A return water pipe G8 is also provided between steam generator 5 and heat exchanger 4. Heat exchanger 4 is also equipped with steam outlet pipe G9, which is equipped with residual steam valve F9.

[0022] The main controller 3 is a PLC controller. Its input terminals are connected to the pressure transmitter P and the temperature sensor T respectively (blue dashed lines), and its output terminals are connected to the feed valve F1, the cryogenic feed valve F2, the reboiler feed valve F3, the spare feed valve F4, the discharge valve F5, the steam valve F6, the nitrogen valve F7, and the steam inlet valve F8 respectively (purple dashed lines).

[0023] The working process of this utility model is as follows: 1. Under normal working conditions; Heat exchanger 4 and steam generator 5 are not working, and all valves on their related pipelines are closed.

[0024] The material (difluoroethane in this embodiment) enters the bottom of the distillation column 1 through the feed pipe G1 without stopping. It then passes through the reboiler pipe G2 and the low-temperature feed valve F2 into the reboiler 2, where it exchanges heat with the steam entering the reboiler 2 through the steam pipe G4. The steam condenses into water and flows out through the condensate pipe G5 into the return water system. After heat exchange, the material is heated and flows back to the distillation column 1 through the temperature sensor T and the reboiler feed valve F3 via the reboiler pipe G2 for distillation. Finally, the product is produced from the discharge pipe G3.

[0025] 2. Under abnormal working conditions; When the steam in steam pipe G4 is abnormal, it is first reflected on the pressure transmitter P, which shows a rapid change in its reading. Then, the temperature sensor T changes its reading. At this time, the signal is transmitted to the main controller 3, which then activates the emergency state for abnormal operation. When the pressure increases suddenly while the temperature remains constant or decreases slightly, it indicates that the steam pipe G4 may be blocked.

[0026] When the pressure drops suddenly and the temperature falls rapidly, it indicates that the steam supply to steam pipe G4 has been interrupted.

[0027] The signals from the pressure transmitter P and the temperature sensor T are transmitted to the main controller 3. The main controller 3 first controls the shut-off valve F1 to prevent new cryogenic materials from entering the system and digests the cryogenic materials that have already entered the system. Then, it closes the steam valve F6, checks the steam pipe G4 for blockage or steam supply issues, and performs maintenance. Simultaneously, it switches the system to the state where the heat exchanger 4 is working, that is, it closes the cryogenic material valve F2, opens the standby material valve F4 and the discharge valve F5, the steam inlet valve F8 and the residual steam valve F9. The following describes the steam path and the material path separately.

[0028] The steam path is as follows: Steam generator 5 is fed with water and produces steam. The steam enters heat exchanger 4 through steam inlet pipe G7 and exchanges heat with the low-temperature material already in reboiler tube G2. The condensate after heat exchange flows back to steam generator 5 through return water pipe G8 to continue producing steam. The steam that has not been completely heat-exchanged escapes and flows into steam pipe G4 through steam outlet pipe G9. It then enters reboiler 2, exchanges heat with the remaining small amount of low-temperature material, condenses, and is discharged from condensate pipe G5.

[0029] The material path is as follows: When the cryogenic material passes through heat exchanger 4, it exchanges heat with steam and then flows along reboiler tube G2 through discharge valve F5 into distillation column 1. Since the residual amount of material flowing through feed valve F1 and cryogenic material valve F2 in reboiler tube G2 after the heat exchange is minimal, a large amount of steam enters reboiler 2 from steam outlet tube G9 after the heat exchange is completed. At this time, the residual material in reboiler 2 is also heated and enters distillation column 1 through reboiler material valve F3.

[0030] Throughout the operation, because the feed valve F1 and steam valve F6 were shut off in time, there was not much residual low-temperature material in the system. It was able to quickly complete the heat exchange and enter the distillation column 1. The temperature of the temperature sensor T could be maintained within the allowable heat exchange range.

[0031] Once all the above steps are completed, if the blockage in steam pipe G4 is cleared or the steam supply is restored, the standby material valve F4 and the discharge valve F5, the steam inlet valve F8 and the residual steam valve F9 can be closed directly, and the low-temperature material valve F2, the steam valve F6, and the feed valve F1 can be opened, and the entire system will return to normal.

[0032] If the fault is still not eliminated after all the above steps are completed, proceed to the next step: complete shutdown and repair.

[0033] 3. Safety purging procedure after all materials have entered the distillation column; In this state, the steam path and the purging path are described separately.

[0034] Steam path: When the steam generator 5 is shut down, steam enters the steam pipe G4 through the steam outlet pipe G9. The steam valve F6 is opened, and finally the steam will come out from the steam pipe G4. A small portion of the condensate will come out from the condensate pipe G5, which will empty the steam generator of any remaining steam.

[0035] Purging path: Keep the feed valve F1 closed, the cryogenic feed valve F2, the reboiler feed valve F3, the standby feed valve F4, and the discharge valve F5 open. The entire material system forms two branches leading to the distillation column (thick black line). Open the nitrogen valve F7 on the nitrogen pipe G6 to purge the reboiler, pipeline, and distillation column. The remaining purging vapor can be discharged from the distillation column. After purging, close the nitrogen valve F7.

[0036] It should be noted that the PLC controller, valves, temperature sensors, and pressure sensors used in this embodiment are all commercially available products. The specific selection and calculation methods are determined based on production capacity and budget. The power supply and principles do not need to be mastered by those skilled in the art. As long as they can be used according to the operating instructions, it will not affect the sufficiency of the disclosure of this utility model, and will not be described in detail here.

Claims

1. A self-antifreezing device for shutting down a low-temperature material distillation reboiler, the device comprising a distillation column (1) and a reboiler (2), wherein a feed valve (F1) is provided on the feed pipe (G1) of the distillation column (1); a steam pipe (G4) and a condensate pipe (G5) are provided on the reboiler (2), and a steam valve (F6) is provided on the steam pipe (G4); the distillation column (1) and the reboiler (2) are connected by a reboiler pipe (G2), wherein a low-temperature feed valve (F2) is provided at any position at the front end of the reboiler (2); characterized in that, It also includes a heat exchanger (4) located between the distillation column (1) and the reboiler (2). The distillation column (1) and the heat exchanger (4) are also connected by a reboiler tube (G2). A spare feed valve (F4) is provided on the reboiler tube (G2) at any position at the front end of the heat exchanger (4), and a discharge valve (F5) is provided on the reboiler tube (G2) at any position at the rear end of the heat exchanger (4). The heat exchanger (4) is connected to a steam generator (5).

2. The self-antifreeze device for shutdown of a low-temperature material distillation reboiler as described in claim 1, characterized in that: A nitrogen pipe (G6) is provided on the reboiler tube (G2) between the distillation column (1) and the reboiler (2) at any position in front of the low temperature feed valve (F2), and a nitrogen valve (F7) is provided on the nitrogen pipe (G6).

3. A self-antifreeze device for shutting down a low-temperature material distillation reboiler as described in claim 1 or 2, characterized in that: The device also includes a main controller (3); a pressure transmitter (P) is also provided on the steam pipe (G4); a temperature sensor (T) is provided on the reboiling pipe (G2) located at the rear end of the reboiler (2) between the distillation column (1) and the reboiler (2); the input end of the main controller (3) is connected to the pressure transmitter (P) and the temperature sensor (T) respectively, and the output end of the main controller (3) is connected to the feed valve (F1), the low temperature feed valve (F2), the standby feed valve (F4), the discharge valve (F5), the steam valve (F6), and the nitrogen valve (F7) respectively.

4. The self-antifreeze device for shutdown of a low-temperature material distillation reboiler as described in claim 3, characterized in that: The heat exchanger (4) is connected to a steam generator (5) via a steam inlet pipe (G7). A steam inlet valve (F8) is provided on the steam inlet pipe (G7). A return water pipe (G8) is also provided between the steam generator (5) and the heat exchanger (4). The heat exchanger (4) is also provided with a steam outlet pipe (G9), which is connected to a steam pipe (G4). A residual steam valve (F9) is provided on the steam outlet pipe (G9). Both the steam inlet valve (F8) and the residual steam valve (F9) are connected to the output end of the main controller (3).

5. The self-antifreeze device for shutdown of a low-temperature material distillation reboiler as described in claim 4, characterized in that: A reboiling valve (F3) is also provided on the reboiling tube (G2) located behind the temperature sensor (T) between the distillation column (1) and the reboiler (2). The reboiling valve (F3) is also connected to the output end of the main controller (3).

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