Device for purifying water-containing acetonitrile through thermal coupling
By using a thermally coupled purification device, the acetonitrile separation towers at different pressures stagger the azeotropic points, thus solving the problem of high energy consumption in the separation of acetonitrile and water, achieving efficient and energy-saving acetonitrile purification with a high recovery rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies consume a lot of energy and require additional extractants in the separation of acetonitrile and water, leading to increased investment in chemical systems.
A thermally coupled purification device is adopted, including a low-pressure acetonitrile separation tower and a high-pressure tower. By adjusting the pressure of the distillation tower to stagger the azeotropic point, the overhead gas of the high-pressure tower is used as the heat source for the reboiler at the bottom of the low-pressure tower, thereby reducing energy consumption.
It achieves the purification of high-purity acetonitrile, reduces energy consumption by 40%-45%, and achieves a recovery rate of 99.9%.
Smart Images
Figure CN224086029U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to an apparatus for purifying acetonitrile, and more particularly to an apparatus for thermally coupled purification of aqueous acetonitrile. Background Technology
[0002] Acetonitrile is a colorless, transparent liquid with excellent solvent properties, capable of dissolving a wide variety of organic, inorganic, and gaseous substances, and is infinitely miscible with water and alcohols. Acetonitrile undergoes typical nitrile reactions and is used to prepare many typical nitrogen-containing compounds, making it an important organic intermediate. In the propylene oxide process, acetonitrile is used as a solvent. During the subsequent separation of acetonitrile and water, an azeotrope forms between them during distillation. Extractive distillation requires the addition of other extractants, which is not only energy-intensive but also necessitates additional extractant separation equipment in subsequent processes, increasing the overall investment in the chemical system. Summary of the Invention
[0003] The technical problem to be solved by this utility model is to provide a simpler, more efficient, and energy-saving device for thermally coupled purification of aqueous acetonitrile.
[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a device for thermally coupled purification of aqueous acetonitrile, comprising an acetonitrile separation low-pressure tower and an acetonitrile separation high-pressure tower, a low-pressure tower top condenser and a low-pressure tower bottom reboiler. An aqueous acetonitrile feed pipe is provided in the middle of the acetonitrile separation low-pressure tower. The gas outlet at the top of the acetonitrile separation low-pressure tower is connected to the gas inlet of the low-pressure tower top condenser. The outlet of the low-pressure tower top condenser is connected to both the middle feed inlet of the acetonitrile separation high-pressure tower and the acetonitrile separation high-pressure tower. The reflux port at the top of the low-pressure tower is connected, the discharge port at the bottom of the acetonitrile separation low-pressure tower is connected to the inlet of the low-pressure tower bottom reboiler, the discharge port of the low-pressure tower bottom reboiler is connected to both the water-containing acetonitrile feed pipe and the reflux port at the bottom of the acetonitrile separation low-pressure tower, the gas outlet at the top of the acetonitrile separation high-pressure tower is connected to the gas inlet of the low-pressure tower bottom reboiler, the bottom of the acetonitrile separation low-pressure tower is provided with a wastewater outlet, and the bottom of the acetonitrile separation high-pressure tower is provided with a high-purity acetonitrile outlet.
[0005] Furthermore, the acetonitrile separation high-pressure tower is equipped with a high-pressure tower bottom reboiler at the bottom of the tower.
[0006] Compared with existing technologies, the advantages of this invention are as follows: This invention provides a thermally coupled purification device for aqueous acetonitrile. Aqueous acetonitrile enters a low-pressure acetonitrile separation tower for separation. The bottom of the tower contains water, and the top contains a mixture of acetonitrile and water (approaching the azeotropic composition at that pressure). The overhead stream then enters a high-pressure acetonitrile separation tower for further separation. The top of this tower contains an azeotrope of acetonitrile and water (approaching the azeotropic composition at that pressure), and the bottom contains acetonitrile with a purity of 99.9%. By using two distillation towers at different pressures to stagger the azeotropic points, high-purity acetonitrile can be obtained. Simultaneously, by adjusting the pressure of the distillation towers, thermal coupling is achieved between the overhead gas from the high-pressure tower and the reboiler at the bottom of the low-pressure tower. The overhead gas from the high-pressure acetonitrile separation tower serves as the heat source for the reboiler in the low-pressure acetonitrile separation tower, reducing the energy consumption of the entire acetonitrile dehydration system by approximately 40%-45%. Attached Figure Description
[0007] Figure 1 This is a schematic diagram of the device for thermally coupled purification of aqueous acetonitrile according to this utility model; the following are the labels in the diagram: acetonitrile separation low-pressure tower 1, acetonitrile separation high-pressure tower 2, low-pressure tower top condenser 3, low-pressure tower bottom reboiler 4, high-pressure tower bottom reboiler 5, aqueous acetonitrile feed pipe 6, wastewater outlet 7, high-purity acetonitrile outlet 8. Detailed Implementation
[0008] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0009] An apparatus for thermally coupled purification of aqueous acetonitrile, such as Figure 1 As shown, the structure includes a low-pressure acetonitrile separation tower 1 and a high-pressure acetonitrile separation tower 2, a low-pressure tower top condenser 3, and a low-pressure tower bottom reboiler 4. A water-containing acetonitrile feed pipe 6 is installed in the middle of the low-pressure acetonitrile separation tower 1. The gas outlet at the top of the low-pressure acetonitrile separation tower 1 is connected to the gas inlet of the low-pressure tower top condenser 3. The outlet of the low-pressure tower top condenser 3 is connected to both the middle feed inlet of the high-pressure acetonitrile separation tower 2 and the top reflux outlet of the low-pressure acetonitrile separation tower 1. The bottom outlet of the acetonitrile separation low-pressure tower 1 is connected to the inlet of the low-pressure tower bottom reboiler 4. The outlet of the low-pressure tower bottom reboiler 4 is connected to the water-containing acetonitrile feed pipe 6 and the bottom reflux port of the acetonitrile separation low-pressure tower 1, respectively. The top outlet of the acetonitrile separation high-pressure tower 2 is connected to the inlet of the low-pressure tower bottom reboiler 4. The bottom of the acetonitrile separation low-pressure tower 1 is equipped with a wastewater outlet 7, and the bottom of the acetonitrile separation high-pressure tower 2 is equipped with a high-purity acetonitrile outlet 8.
[0010] Furthermore, a high-pressure reboiler 5 is installed at the bottom of the acetonitrile separation high-pressure tower 2.
[0011] The working process of the above-mentioned device is as follows: a mixture of acetonitrile and water from the boundary area is about 60.46 t / h at a temperature of 110℃, of which the acetonitrile content is 73.8% and the remainder is water. First, the acetonitrile enters the low-pressure acetonitrile separation tower 1 for separation. The pressure of the low-pressure acetonitrile separation tower 1 is 0.01 MPaG, the top temperature is 79.5℃, the theoretical plate number is 15, and the bottom composition is 99.99% water at 15.8 t / h, which is discharged as wastewater to be treated outside the boundary. The top composition is 21% water and 79% acetonitrile, which is sent to the high-pressure acetonitrile separation tower 2 at 181.7 t / h for separation. The pressure of the high-pressure acetonitrile separation tower 2 is 0.6 MPaG, the top temperature is 143℃, the theoretical plate number is 20, and the top composition is 28% water and 72% acetonitrile. It is first sent to the reboiler 4 at the bottom of the low-pressure tower to utilize heat, and then mixed with the mixture of acetonitrile and water from the boundary area before being sent back to the low-pressure acetonitrile separation tower 1 for circulation. The bottom composition is 99.9% acetonitrile, which is sent outside the boundary as product at 44.656 t / h. This device achieves a 99.9% recovery rate of acetonitrile and saves a significant amount of energy. Details not described in this embodiment are well-known in the art.
[0012] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this utility model, and these should all be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.
Claims
1. An apparatus for thermally coupled purification of aqueous acetonitrile, characterized in that: The system includes a low-pressure acetonitrile separation tower and a high-pressure acetonitrile separation tower, a low-pressure tower top condenser, and a low-pressure tower bottom reboiler. The low-pressure acetonitrile separation tower has a water-containing acetonitrile feed pipe in its middle section. The top outlet of the low-pressure acetonitrile separation tower is connected to the inlet of the low-pressure tower top condenser. The outlet of the low-pressure tower top condenser is connected to both the middle feed inlet of the high-pressure acetonitrile separation tower and the top reflux outlet of the low-pressure acetonitrile separation tower. The bottom outlet of the low-pressure acetonitrile separation tower is connected to the inlet of the low-pressure tower bottom reboiler. The outlet of the low-pressure tower bottom reboiler is connected to both the water-containing acetonitrile feed pipe and the bottom reflux outlet of the low-pressure acetonitrile separation tower. The top outlet of the high-pressure acetonitrile separation tower is connected to the inlet of the low-pressure tower bottom reboiler. The low-pressure acetonitrile separation tower has a wastewater outlet at its bottom, and the high-pressure acetonitrile separation tower has a high-purity acetonitrile outlet at its bottom.
2. The apparatus for thermally coupled purification of aqueous acetonitrile according to claim 1, characterized in that: The acetonitrile separation high-pressure tower is equipped with a high-pressure tower bottom reboiler at the bottom.