Device capable of reducing dimer in circulating solvent of large butadiene extraction device

Abstract

The utility model discloses a device capable of reducing dimers in a circulating solvent of a large butadiene extraction device, which comprises an acetonitrile circulating tank, and the outlet end of the acetonitrile circulating tank is connected with an extraction tower group through a pipeline. The outlet end of the extraction tower group is sequentially connected with a middle reboiler, a heavy component removal tower kettle reboiler, a dehydrogenation tower kettle reboiler, a feeding heater and an acetonitrile cooler through pipelines, and the acetonitrile cooler is connected to the inlet end of an acetonitrile circulating tank through a pipeline to form circulation; the device further comprises a buffer tank 1 used for storing the auxiliary polymerization inhibitor of the butadiene device, the buffer tank is connected with a filling pump through a pipeline, the filling pump is connected with an acetonitrile feeding heat exchanger through a pipeline, and the acetonitrile feeding heat exchanger is connected with the extraction tower set through a pipeline. The stable production of butadiene products is ensured, and the economic benefit of the whole device is improved.

Description

Technical Field

[0001] This utility model relates to a device, and more specifically, to a device that can reduce dimers in the circulating solvent of a large butadiene extraction device, belonging to the field of petrochemicals. Background Technology

[0002] Extractive distillation columns are complex separation devices with multiple functions. Their notable characteristics include a large throughput of liquid feedstock and a relatively small throughput of gaseous feedstock, with a small density difference between the gas and liquid phases. During operation, butadiene and alkynes readily polymerize at high temperatures, forming viscous, rubbery polymers. These polymers accumulate on the trays and at the float valves of the extractive distillation column, affecting normal operation and severely impacting the separation efficiency within the column. This polymer adhesion significantly negatively affects the separation function of the trays. Simultaneously, polymers enter the bottom of the extraction column with the circulating solvent, and some even deposit in the reboiler and other tube bundles, significantly increasing the risk of clogging in the reboiler and bottom filter, leading to reduced heat exchange efficiency. In actual production, heat exchange efficiency gradually decreases as polymers accumulate. The outlet temperature of the reboiler is often maintained by increasing steam pressure, steam flow rate, and steam temperature. As steam consumption gradually increases, the polymer formation rate is faster, and the reboiler often becomes blocked rapidly within the next one to two months, completely unable to heat up. At the same time, due to the increase in reboiler steam consumption, the reboiler steam temperature is relatively high. Acetonitrile solvent contains about 5%-7% water, which is prone to hydrolysis at high temperatures to generate acetic acid, thereby causing corrosion and leakage of the reboiler tube bundle.

[0003] In the existing technology, the starting point for adding auxiliary polymerization inhibitors to the circulating acetonitrile in butadiene units is at the top of the acetonitrile circulating tank. According to the actual operation of the unit, the concentration distribution of auxiliary polymerization inhibitors in the circulating solvent is uneven, and the content in the circulating solvent is unstable, which cannot achieve the expected polymerization inhibition effect. This results in poor polymerization inhibition effect of the extractive distillation system, frequent blockage of the reboiler, and short operating cycle. Therefore, it is necessary to develop a new device to improve and solve the problem. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model provides a device that reduces dimer in the circulating solvent of a large-scale butadiene extraction unit. This device features a simple structure, strong practicality, ensures continuous and stable operation of the unit, guarantees stable production of butadiene products, and improves the overall economic efficiency of the unit.

[0005] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0006] This invention relates to a device for reducing dimer in the circulating solvent of a large butadiene extraction unit. The device includes an acetonitrile circulating tank. The outlet of the acetonitrile circulating tank is connected to an extraction tower assembly via a pipeline. The outlet of the extraction tower assembly is sequentially connected via pipelines to an intermediate reboiler, a de-heavyweight tower reboiler, a dehydrogenation tower reboiler, a feed heater, and an acetonitrile cooler. The acetonitrile cooler is connected via a pipeline to the inlet of the acetonitrile circulating tank to form a circulation system. The device also includes a buffer tank 1 for storing auxiliary polymerization inhibitors for the butadiene unit. The buffer tank is connected via a pipeline to a filling pump. The filling pump is connected via a pipeline to an acetonitrile feeding heat exchanger, which is connected via a pipeline to the extraction tower assembly.

[0007] Preferably, the extraction tower group includes an upper extraction tower, a lower extraction tower, a second upper extraction tower, and a second lower extraction tower;

[0008] The outlet of the acetonitrile circulating tank is connected to an acetonitrile circulating pump via a pipeline. The outlet of the acetonitrile circulating pump is provided with two pipelines: Pipeline 1 and Pipeline 2. Pipeline 1 is connected to the acetonitrile feed heat exchanger, and Pipeline 2 is connected to the 28th section of the upper column of the first extraction. The outlet of the upper column of the first extraction is connected to the 1st section of the lower column of the first extraction via a pipeline equipped with a bottom pump of the upper column of the first extraction. The outlet of the lower column of the first extraction is connected to the 44th section of the lower column of the second extraction via a bottom pump of the lower column of the first extraction. The acetonitrile feed heat exchanger is connected to the 17th section of the upper column of the second extraction via a pipeline. The outlet of the upper column of the second extraction is connected to the 43rd section of the lower column of the second extraction via a pipeline equipped with a bottom pump of the upper column of the second extraction. The outlet of the lower column of the second extraction is connected to the intermediate reboiler via a pipeline equipped with a bottom pump of the lower column of the second extraction.

[0009] Preferably, the injection pump is provided with a No. 3 pipeline and a No. 4 pipeline. The No. 3 pipeline is connected to the acetonitrile feeding heat exchanger, and the No. 4 pipeline is connected to the pipeline between the acetonitrile cooler and the acetonitrile circulating tank.

[0010] Preferably, it also includes a DCS controller, wherein the intermediate reboiler, the de-heavy tower reboiler, the dehydrogenation tower reboiler, the feed heater, the acetonitrile cooler, and each pump are all connected to the DCS controller.

[0011] Preferably, the DCS controller includes an electrically connected processor, external devices, and a communication module.

[0012] Preferably, the external device includes a sensor and an actuator.

[0013] Beneficial effects: This invention features a simple structure and convenient operation, effectively slowing down the formation of dimers in the circulating solvent. It completely solves the problem of high dimer content in the circulating solvent affecting the butadiene extraction unit, reducing employee workload and the frequency of unit maintenance. This reduces downtime maintenance costs, ensures continuous and stable operation of the unit, guarantees stable butadiene production, and significantly impacts the overall economic benefits of the plant. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model. Detailed Implementation

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

[0016] The technical solution of this application is applicable to reducing dimers in the circulating solvent of large-scale butadiene extraction units using the acetonitrile process, so as to completely solve the problem of high dimer content in circulating propane causing problems for butadiene extraction units, reduce the frequency of unit maintenance, and increase the production load of butadiene extraction units.

[0017] like Figure 1The illustration shows a specific embodiment of a device for reducing dimers in the circulating solvent of a large-scale butadiene extraction unit. This device includes an acetonitrile circulation tank V-0101. The outlet of the acetonitrile circulation tank V-0101 is connected to an extraction tower group via a pipeline. The outlet of the extraction tower group is sequentially connected via pipelines to a (primary extraction) intermediate reboiler E-104, a de-heavyweight tower reboiler E-303, a dehydrogenation tower reboiler E-304, and a (primary extraction) feed heater. E-102 and acetonitrile cooler E-101 are included. The acetonitrile cooler E-101 is connected via pipeline to the inlet of acetonitrile circulation tank V-0101 to form a circulation system. The system also includes a buffer tank 1 for storing auxiliary polymerization inhibitors for the butadiene unit. The buffer tank 1 is connected via pipeline to a filling pump 2, which is connected via pipeline to an acetonitrile feed heat exchanger E-0202. The acetonitrile feed heat exchanger E-0202 is connected via pipeline to an extraction tower group, which includes an upper extraction tower C-102 and a lower extraction tower C-102. 101, Upper column of secondary extraction C-202, Lower column of secondary extraction C-201; The outlet end of the acetonitrile circulation tank V-0101 is connected to an acetonitrile circulation pump 7 via a pipeline. The outlet end of the acetonitrile circulation pump 7 is provided with a first pipeline and a second pipeline. The first pipeline is connected to the acetonitrile feed heat exchanger E-0202, and the second pipeline is connected to the 28th section of the upper column of primary extraction C-102. The outlet end of the upper column of primary extraction C-102 is connected to the first section of the lower column of primary extraction C-101 via a pipeline equipped with the upper column reboiler pump 3. The outlet of the lower column C-101 of the first extraction is connected to the 44th section of the lower column C-201 of the second extraction via a pump 4. The acetonitrile feed heat exchanger E-0202 is connected to the 17th section of the upper column C-202 of the second extraction via a pipeline. The outlet of the upper column C-202 of the second extraction is connected to the 43rd section of the lower column C-201 of the second extraction via a pipeline 5. The outlet of the lower column C-201 of the second extraction is connected to the intermediate reboiler E-104 via a pipeline 6.

[0018] This application utilizes a multi-pump design with an upper extraction tower (C-102), a lower extraction tower (C-101), an upper extraction tower (C-202), a lower extraction tower (C-201), and an auxiliary inhibitor injection pump at the butadiene unit's auxiliary inhibitor injection pump outlet, extending to the inlet pipeline of the (secondary extraction) acetonitrile feed heat exchanger. A flow meter can be configured to monitor the amount of auxiliary inhibitor injected into the circulating acetonitrile. This application enables the auxiliary inhibitor to enter the extraction tower group along with the solvent, achieving a more uniform distribution of the auxiliary inhibitor in the solvent. This improves the inhibitory effect of the auxiliary inhibitor in the extraction system, achieving comprehensive and thorough inhibition of butadiene self-polymerization within the reboiler. This reduces the formation of dimers in the circulating solvent, completely resolving the problem of high dimer content in the circulating solvent affecting the butadiene extraction unit, providing a permanent solution and reducing the frequency of unit maintenance.

[0019] In actual production, the design scheme of this application was tested from July to August 2023. The amount of auxiliary polymerization inhibitor added to the No. 1 butadiene unit was normal. As of September 2024, the reboiler of the second extraction was operating normally.

[0020] In a preferred embodiment, the filling pump 2 is provided with a third pipeline and a fourth pipeline. The third pipeline is connected to the acetonitrile feeding heat exchanger E-0202, and the fourth pipeline is connected between the acetonitrile cooler E-101 and the acetonitrile circulating tank V-0101. This improves the flexibility of the filling pump and allows for filling of the acetonitrile circulating tank as in traditional technology for short-term operations.

[0021] In a preferred embodiment, the system further includes a DCS controller. The intermediate reboiler E-104, the de-heavyweight tower reboiler E-303, the dehydrogenation tower reboiler E-304, the feed heater E-102, the acetonitrile cooler E-101, and each pump are all connected to the DCS controller. The DCS controller includes an electrically connected processor, external devices, and a communication module. The external devices include sensors and actuators. The DCS controller facilitates remote monitoring and operation by personnel.

[0022] Finally, it should be noted that this utility model is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this utility model should be considered within the protection scope of this utility model.

Claims

1. An apparatus for reducing the level of dimers in the circulating solvent of a large scale butadiene extraction unit, characterized by: The device comprises an acetonitrile circulating tank (V-0101), an extraction column group connected to the outlet end of the acetonitrile circulating tank (V-0101) through a pipeline, an intermediate reboiler (E-104), a de-heavy column reboiler (E-303), a dehydrogenation column reboiler (E-304), a feed heater (E-102), and an acetonitrile cooler (E-101) connected to the inlet end of the acetonitrile circulating tank (V-0101) through a pipeline in sequence to form a circulation; and a buffer tank (1) for storing a butadiene device auxiliary polymerization inhibitor, a filling pump (2) connected to the buffer tank (1) through a pipeline, and an acetonitrile feeding heat exchanger (E-0202) connected to the extraction column group through a pipeline.

2. The apparatus of claim 1 wherein: The extraction column group comprises a first extraction upper column (C-102), a first extraction lower column (C-101), a second extraction upper column (C-202), and a second extraction lower column (C-201). The outlet end of the acetonitrile circulating tank (V-0101) is connected to an acetonitrile circulating pump (7) through a pipeline, the outlet end of the acetonitrile circulating pump (7) is divided into a first pipeline and a second pipeline, the first pipeline is connected to the acetonitrile feeding heat exchanger (E-0202), and the second pipeline is connected to the 28th segment of the first extraction upper column (C-102); the outlet end of the first extraction upper column (C-102) is connected to the 1st segment of the first extraction lower column (C-101) through a pipeline with a first extraction upper column reboiler (3); the outlet end of the first extraction lower column (C-101) is connected to the 44th segment of the second extraction lower column (C-201) through a pipeline with a first extraction lower column reboiler (4); the acetonitrile feeding heat exchanger (E-0202) is connected to the 17th segment of the second extraction upper column (C-202) through a pipeline; the outlet end of the second extraction upper column (C-202) is connected to the 43rd segment of the second extraction lower column (C-201) through a pipeline with a second extraction upper column reboiler (5); and the outlet end of the second extraction lower column (C-201) is connected to the intermediate reboiler (E-104) through a pipeline with a second extraction lower column reboiler (6).

3. The apparatus for reducing the level of dimers in the circulating solvent of a large scale butadiene extraction plant according to claim 1 or 2, characterized in that: The filling pump (2) is divided into a third pipeline and a fourth pipeline, the third pipeline is connected to the acetonitrile feeding heat exchanger (E-0202), and the fourth pipeline is connected to the pipeline between the acetonitrile cooler (E-101) and the acetonitrile circulating tank (V-0101).

4. The apparatus of claim 3 wherein: The device further comprises a DCS controller, and the intermediate reboiler (E-104), the de-heavy column reboiler (E-303), the dehydrogenation column reboiler (E-304), the feed heater (E-102), the acetonitrile cooler (E-101), and each pump are connected to the DCS controller.

5. The apparatus of claim 4 wherein: The DCS controller comprises a processor, an external device, and a communication module connected in an electrical manner.

6. The apparatus of claim 5 wherein: The external device comprises a sensor and an actuator.

Images