Device for recovering caprolactam by using pyrolysis gas

Abstract

The utility model discloses a device for recovering caprolactam by using pyrolysis gas. Comprising a cyclone separator, a water storage device, a spraying device, a condenser and an extraction separation tower, the cyclone separator is provided with a cracked gas inlet, and a gas outlet at the upper end of the cyclone separator is connected with the spraying device; the upper end of the spraying device is connected with a water storage device, and the water storage device provides spraying water for the spraying device; a lower end liquid outlet of the spraying device is connected with a lower end liquid inlet of the extraction separation tower; the extraction separation tower is respectively connected with an upper end outlet and is respectively connected with the spraying device and the combustion device; a gas outlet at the upper end of the spraying device is connected with the condenser, and a liquid outlet of the condenser is connected with the spraying device to form a circulation loop. The cyclone separator is arranged to remove trace particles in pyrolysis gas, the condensing device is connected to the spraying device, so that steam condensate returns to the spraying device, the utilization rate of the pyrolysis gas is increased, the extraction rate of caprolactam is increased by repeatedly extracting the pyrolysis liquid, and important value is brought to enterprises.

Description

Technical Field

[0001] This utility model belongs to the field of caprolactam recovery technology, specifically relating to a device for recovering caprolactam using pyrolysis gas. Background Technology

[0002] Nylon 6 (polycaprolactam) is an important chemical raw material with high strength, oil resistance, and shock resistance, and is widely used in machine tools, automobiles, machinery, chemicals, textiles, transportation, and other industrial sectors. Nylon 6 is generally obtained through ring-opening polymerization of caprolactam. During the industrial production of nylon 6, a large amount of cracked gas is often generated in the polymerization reactor. This cracked gas contains caprolactam, oligomers, and a small amount of solid particles. This cracked gas is often unrecoverable and is directly burned in the industrial park's flare system, resulting in significant waste of raw materials and a serious environmental burden.

[0003] Raw material utilization and environmental protection are currently important factors restricting enterprise development. As enterprises expand, the amount of pyrolysis gas generated during nylon 6 production increases significantly. Furthermore, with growing emphasis on environmental standards, the recycling and utilization of pyrolysis gas is receiving increasing attention. Caprolactam constitutes a high proportion of pyrolysis gas and has significant recovery value. To save costs and improve resource utilization, current technologies often employ evaporation recovery systems to recover and concentrate wastewater containing caprolactam and oligomers. This wastewater is then re-mixed with caprolactam raw materials and fed into a pyrolysis system for oligomer pyrolysis and repolymerization before being fed into a polymerization system for production. However, the high cost of oligomer pyrolysis and repolymerization hinders its widespread adoption.

[0004] Therefore, it is of great significance to develop a technology for recovering caprolactam from pyrolysis gas. Summary of the Invention

[0005] To address the difficulties in recovering and utilizing caprolactam from the cracked gas produced in the existing technology for nylon 6 production, and the problem that direct combustion causes resource waste and environmental pollution, this utility model provides a device for recovering caprolactam from cracked gas. By adding a centrifugal sedimentation and extraction separation system, the recovery of caprolactam and oligomeric fuels can bring significant value to enterprises.

[0006] This utility model is achieved through the following technical solution:

[0007] An apparatus for recovering caprolactam using cracked gas includes a cyclone separator, a water storage device, a spray device, a condenser, and an extraction separation tower.

[0008] The cyclone separator is equipped with a cracked gas inlet, and the gas outlet at the upper end of the cyclone separator is connected to a spray device.

[0009] The upper end of the spraying device is connected with a water storage device, and the water storage device provides water for the spraying device;

[0010] The lower end liquid outlet of the spraying device is connected with the lower end liquid inlet of the extraction separation tower, and the upper end outlet of the extraction separation tower is connected with the spraying device and the combustion device respectively.

[0011] The upper end gas outlet of the spraying device is connected with a condenser, and the liquid outlet of the condenser is connected with the spraying device, so as to form a circulating loop.

[0012] Further, the lower end of the cyclone separator is provided with a solid outlet.

[0013] Further, the lower end liquid outlet of the spraying device is connected with the lower end liquid inlet of the extraction separation tower through a conveying pump.

[0014] Further, the upper end of the extraction separation tower is provided with an extractant adding port.

[0015] Further, the extraction separation tower is provided with an extractant and caprolactam outlet.

[0016] Further, the condenser is provided with a condensate water inlet and a condensate water outlet.

[0017] Beneficial effects

[0018] The cyclone separator is arranged to remove the trace particles in the cracking gas, the condensing device is connected with the spraying device, the steam condensate returns to the spraying device, and the utilization rate of the cracking gas is improved. The cracking liquid is repeatedly extracted, the extraction rate of caprolactam is improved, and the recovery of caprolactam and oligomer fuel can bring important value to enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The device for recovering caprolactam by cracking gas is shown in the schematic view of the utility model, 1. Cyclone separator, 2. Water storage device, 3. Spraying device, 4. Condenser, 5. Extraction separation tower. DETAILED DESCRIPTION

[0020] The above content of the utility model will be further described in detail through the following examples and drawings, but this should not be understood as the scope of the above subject matter of the utility model being limited to the following examples. Any technology realized based on the above content of the utility model belongs to the scope of the utility model.

[0021] The device for recovering caprolactam by cracking gas in the utility model is shown in the schematic view as Figure 1 shown, such as Figure 1As shown, the device for recovering caprolactam from cracking gas comprises a cyclone 1, a water storage device 2, a spraying device 3, a condenser 4 and an extraction separation tower 5; the cyclone 1 is provided with a cracking gas inlet, and the upper end gas outlet of the cyclone 1 is connected with the spraying device 3; the upper end of the spraying device 3 is connected with the water storage device 2, and the water storage device 2 provides spraying water for the spraying device 3; the lower end liquid outlet of the spraying device 3 is connected with the lower end liquid inlet of the extraction separation tower 5, and the upper end outlet of the extraction separation tower 5 is connected with the spraying device 3 and a combustion device respectively; the upper end gas outlet of the spraying device 3 is connected with the condenser 4, and the liquid outlet of the condenser 4 is connected with the spraying device, forming a circulating loop.

[0022] The lower end of the cyclone 1 is provided with a solid outlet; the lower end liquid outlet of the spraying device 3 is connected with the lower end liquid inlet of the extraction separation tower 5 through a conveying pump; the upper end of the extraction separation tower 5 is provided with an extractant adding port; the extraction separation tower 5 is provided with extractant and caprolactam outlets; and the condenser is provided with a condensate water inlet and a condensate water outlet.

[0023] The device for recovering caprolactam from cracking gas will be described in combination with the drawings and specific embodiments.

[0024] Embodiment 1

[0025] (1) Nylon 6 is prepared by taking caprolactam as raw material, and cracking gas (containing 50wt% of caprolactam, 45wt% of oligomers and the rest of trace solid particles) is connected with the cyclone 1. The cracking gas enters the cyclone 1 through the gas inlet of the cyclone 1, and after separation, the trace particles are discharged from the solid outlet at the lower end of the cyclone 1. The separated gas is discharged from the gas outlet at the upper end of the cyclone 1 into the spraying device 3. The water in the water storage device 2 is introduced into the water inlet at the upper end of the spraying device through the spraying device 2, and the water in the spraying device 3 is sprayed into the spraying device 3 to absorb the gas in the cracking gas and convert the gas phase into the liquid phase. At the same time, due to the high temperature of the cracking gas, steam is inevitably formed. The gas is condensed in the condenser 4 through the gas outlet at the upper end of the spraying device 3, and is converted into liquid in the condenser 4. The liquid is introduced into the spraying device 3 through the liquid outlet of the condenser 4;

[0026] (2) The liquid in the spraying device 3 is introduced into the lower end of the extraction separation tower 5 through the conveying pump, and the extractant (caprolactam) is added into the extraction separation tower 5 through the extractant adding port at the upper end of the extraction separation tower 5. The content of caprolactam in the raffinate after extraction is detected online. When the content of caprolactam is relatively high, the raffinate is introduced into the spraying device 3 through the outlet at the upper end of the extraction separation tower 5, and the cycle is repeated until the content of caprolactam in the raffinate is reduced to a relatively low level.

[0027] (3) The raffinate (low polymer) with low caprolactam content from the extraction separation tower 5 enters a combustion device (boiler) to provide fuel, and the extract enters the rearrangement unit through the extractant and caprolactam outlet at the lower end of the extraction separation tower 5 for recycling.

[0028] Although the specific embodiments of the patent have been described in detail above with reference to the accompanying drawings, the above description is not intended to limit the scope of protection of the patent. Those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the patent without creative labor are still within the scope of protection of the patent.

Claims

1. An apparatus for recovering caprolactam using cleavage gas, characterized by comprising: It comprises a cyclone separator (1), a water storage device (2), a spraying device (3), a condenser (4) and an extraction separation tower (5); The cyclone separator (1) is provided with a cracking gas inlet, and the upper end gas outlet of the cyclone separator (1) is connected with the spraying device (3); The upper end of the spraying device (3) is connected with the water storage device (2), and the water storage device (2) provides spraying water for the spraying device (3); The lower end liquid outlet of the spraying device (3) is connected with the lower end liquid inlet of the extraction separation tower (5), and the upper end outlet of the extraction separation tower (5) is connected with the spraying device (3) and a combustion device respectively; The upper end gas outlet of the spraying device (3) is connected with the condenser (4), and the liquid outlet of the condenser (4) is connected with the spraying device (3), forming a circulating loop.

2. The apparatus for recovering caprolactam with a cracking gas according to claim 1, characterized by, The lower end of the cyclone separator (1) is provided with a solid outlet.

3. The apparatus for recovering caprolactam with a cracking gas according to claim 1, characterized by, The lower end liquid outlet of the spraying device (3) is connected with the lower end liquid inlet of the extraction separation tower (5) through a conveying pump.

4. The apparatus for recovering caprolactam with a cracking gas according to claim 1, characterized by, The upper end of the extraction separation tower (5) is provided with an extractant adding port.

5. The apparatus for recovering caprolactam with a cracking gas according to claim 1, characterized by, The extraction separation tower (5) is provided with an extractant and caprolactam outlet.

6. The apparatus for recovering caprolactam with a cracking gas according to claim 1, characterized by, The condenser is provided with a condensate water inlet and a condensate water outlet.

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