A pressure swing adsorption dust removal device for vinyl chloride

Abstract

This utility model relates to the field of chemical production technology, specifically a vinyl chloride pressure swing adsorption (PSA) dust removal device, comprising an adsorption tower, a preheater, and an adsorption dust removal system disposed between the adsorption tower and the preheater. The adsorption dust removal system includes a buffer tank and a dust collector. The outlet of the adsorption tower is connected to the inlet of the buffer tank via an adsorption tower outlet pipe, the outlet of the buffer tank is connected to the inlet of the dust collector, and the outlet pipe of the dust collector is connected to the inlet of the preheater via a dust collector outlet pipe. This utility model features a combined design of the buffer tank and dust collector, along with staggered inclined baffles inside the outlet pipe, achieving efficient dust separation through inertial settling, significantly improving the dust removal rate. It avoids molecular sieve powder entering the preheater and other downstream equipment, solving problems of pipe blockage and equipment corrosion, while also protecting the adsorbent pores from blockage and extending the adsorbent's service life.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to a pressure swing adsorption dust removal device for vinyl chloride. Background Technology

[0002] Vinyl chloride is the core raw material for the production of polyvinyl chloride (PVC). During its production and distillation, dust impurities are generated due to adsorbent pulverization and raw material entrainment. These dusts can not only cause blockages in the subsequent distillation system and equipment corrosion, but also affect the quality of PVC resin products. Therefore, dust removal and purification of vinyl chloride gas is a key process in the industry.

[0003] Currently, vinyl chloride gas dust removal and related purification technologies are mainly divided into two categories: one is a process specifically designed for dust removal, such as Chinese utility model patent CN220589273U. One publicly disclosed high-efficiency vinyl chloride gas dust removal system involves adding a low-pressure pulse-jet bag filter between the dehydration unit and the total condenser. While this system filters dust through the filter bags and periodically cleans them with pulse-jet cleaning, it suffers from several drawbacks. These include the filter bags being susceptible to corrosion from vinyl chloride gases, the need to interrupt airflow during cleaning leading to poor system continuity, and high maintenance costs after filter bag blockage. Another type of vinyl chloride purification technology is based on pressure swing adsorption (PSA), such as the full-temperature range PSA method for vinyl chloride dehydration disclosed in Chinese invention patent CN107281894B. This technology achieves vinyl chloride dehydration and recovery through PSA, with low energy consumption and a long adsorbent lifespan. However, this process focuses primarily on moisture removal and does not design a dedicated adsorption and separation structure for dust impurities. When directly applied to dust removal scenarios, it is prone to problems such as dust clogging of the adsorbent channels and a decrease in adsorption-desorption cycle efficiency.

[0004] In addition, traditional vinyl chloride tail gas treatment technologies include activated carbon adsorption and membrane separation. Activated carbon adsorption has limited dust removal efficiency and high regeneration energy consumption, while membrane separation technology suffers from drawbacks such as easy fouling of membrane modules and difficulty in simultaneously achieving separation accuracy and gas recovery rate. Currently, pressure swing adsorption (PSA) dust collectors specifically adapted to the characteristics of vinyl chloride are not yet mature. The combination of existing dust removal technologies with PSA has significant shortcomings: simple baghouse dust collection suffers from poor continuity and high maintenance costs; and simple PSA technology is not optimized for dust, failing to simultaneously meet the industrial demands for efficient dust removal, low energy consumption operation, and efficient vinyl chloride recovery.

[0005] Therefore, developing a vinyl chloride pressure swing adsorption dust removal device that combines high dust removal efficiency, stable operation, and good adsorbent regeneration effect to solve the problems of difficulty in balancing dust removal and gas recovery and frequent equipment maintenance in existing technologies has become an urgent technical challenge in this field. Utility Model Content

[0006] The purpose of this invention is to provide a vinyl chloride pressure swing adsorption dust removal device to solve the problems mentioned in the prior art in the background section.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a vinyl chloride pressure swing adsorption dust removal device, comprising an adsorption tower, a preheater, and an adsorption dust removal system disposed between the adsorption tower and the preheater, wherein the adsorption dust removal system comprises a buffer tank and a dust collector; the outlet of the adsorption tower is connected to the inlet of the buffer tank through an adsorption tower outlet pipe, the outlet of the buffer tank is connected to the inlet of the dust collector, and the outlet pipe of the dust collector is connected to the inlet of the preheater through a dust collector outlet pipe.

[0008] Furthermore, the outlet pipe is provided with multiple baffles, which are staggered on the inner wall of the outlet pipe and are all arranged at a downward angle.

[0009] Furthermore, a regulating valve is provided on the outlet pipe of the adsorption tower, and a flow meter is provided on the buffer tank. The regulating valve and the flow meter are interlocked and used in conjunction.

[0010] Furthermore, the dust collector is equipped with a differential pressure gauge.

[0011] Furthermore, the regulating valve, flow meter, and differential pressure gauge are all connected to the PLC controller.

[0012] The core beneficial effect of this utility model is that it balances efficient dust removal, stable operation, and low maintenance costs, specifically addressing the shortcomings of existing technologies and adapting to the needs of vinyl chloride chemical production. Details are as follows: 1. This utility model combines a buffer tank and a dust collector, with staggered inclined baffles inside the outlet pipe, to efficiently separate dust through the principle of inertial settling, significantly improving the dust removal rate. It prevents molecular sieve powder from entering subsequent equipment such as the preheater, solving problems of pipe blockage and equipment corrosion, while also protecting the adsorbent pores from clogging and extending the adsorbent's service life.

[0013] 2. This utility model's buffer tank can reduce pressure fluctuations in vinyl chloride gas (fluctuation range ≤ ±0.02MPa). Combined with the regulating valve and flow meter interlocked on the adsorption tower outlet pipeline, it ensures a stable gas flow rate of 500-800 Nm³. 3 / h. No interruption of airflow for dust removal is required. Compared to baghouse dust collection technology, the system's continuous operation capability is significantly improved, avoiding the impact of operating condition fluctuations on the vinyl chloride synthesis process.

[0014] 3. This utility model dust collector adopts a baffle plate settling structure, eliminating the need for easily corroded filter bag components. The selection of materials resistant to vinyl chloride corrosion (316L stainless steel, PTFE coating, etc.) reduces equipment wear. The PLC controller is linked with the differential pressure gauge, flow meter, and regulating valve to monitor the dust collector's blockage status in real time (alarm when differential pressure exceeds 8kPa), facilitating timely cleaning and reducing manual inspection and maintenance costs.

[0015] 4. The overall design of this utility model is tailored to the characteristics of the vinyl chloride pressure swing adsorption process, achieving efficient dust removal without affecting the vinyl chloride gas recovery efficiency, thus balancing purification and recovery needs. Stable flow and pressure control improves the heat exchange efficiency of the preheater, keeping the vinyl chloride gas outlet temperature stable at 80-90℃, which helps optimize energy consumption in subsequent processes. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a system block diagram of the present invention.

[0017] In the diagram: 1. Adsorption tower; 2. Preheater; 3. Buffer tank; 4. Dust collector; 5. Adsorption tower outlet pipe; 6. Outlet pipe; 7. Dust collector outlet pipe; 8. Baffle plate; 9. Control valve; 10. Flow meter; 11. Differential pressure gauge. Detailed Implementation

[0018] The following is in conjunction with the appendix Figure 1 and Figure 2 This document provides a detailed description of the specific implementation of a vinyl chloride pressure swing adsorption dust removal device according to the present invention. This embodiment is only used to explain the present invention and is not intended to limit the scope of protection of the present invention.

[0019] like Figure 1 , Figure 2As shown, the vinyl chloride pressure swing adsorption (PSA) dust removal device in this embodiment mainly solves two problems existing in the current vinyl chloride PSA system: First, the molecular sieve packed in the adsorption tower 1 is prone to pulverization during long-term operation. The pulverized molecular sieve powder will enter subsequent equipment such as the preheater 2 with the vinyl chloride recovery gas, causing equipment pipeline blockage and affecting the continuous operation of the system; Second, the pressure fluctuation of the vinyl chloride gas discharged from the adsorption tower 1 is large. Directly entering the subsequent process will cause the heat exchange efficiency of the preheater 2 to be unstable, thus affecting the operating stability of the entire vinyl chloride synthesis process. This device mainly includes an adsorption tower 1, a preheater 2, and an adsorption dust removal system set between the adsorption tower 1 and the preheater 2, and is equipped with control and monitoring components and auxiliary connection components. The adsorption dust removal system consists of a buffer tank 3 and a dust collector 4; the control and monitoring components consist of a regulating valve 9, a flow meter 10, a differential pressure gauge 11, and a PLC controller; the auxiliary connection components consist of a baffle plate 8, an adsorption tower outlet pipe 5, a dust collector outlet pipe 6, a dust collector outlet pipe 7, and flanges / bolts / seals. Details are as follows: The main body of adsorption tower 1 is made of 316L stainless steel, with an inner wall lined with polytetrafluoroethylene (PTFE) coating for resistance to vinyl chloride corrosion; its specifications are Φ800×4500mm (diameter×height), with an effective volume of 2.2m³. 3 The design pressure is 1.0 MPa, and the wall thickness is 12 mm. It is internally filled with 13X type molecular sieves at a height of 3.5 m, and the bottom is supported by a stainless steel perforated sieve plate (5 mm aperture). The shell of preheater 2 is made of 304 stainless steel, and the heat exchange tubes are made of Hastelloy C-276; it is a shell-and-tube heat exchanger with an F-type structure and a heat exchange area of ​​20m². 2 The design pressure is 1.0 MPa, the pipe diameter is 25 mm, and the pipe length is 2000 mm. The heating medium is 120℃ saturated steam, and the outlet temperature of vinyl chloride gas is controlled at 80-90℃.

[0020] Buffer tank 3 is made of 304 stainless steel with a wall thickness of 8mm; its specifications are Φ600×1800mm, and its effective volume is 0.5m³. 3 The design pressure is 1.0 MPa, and the working pressure is 0.3-0.6 MPa. A safety valve (model A28H-16C, opening pressure 0.7 MPa) is installed at the top, and a drain port (DN25, equipped with a ball valve) is installed at the bottom. The dust collector's shell is made of 316L stainless steel, and the internal components are made of the same material; its specifications are Φ500×1500mm, and its air handling capacity is 500-800Nm³. 3 / h, pressure loss ≤5kPa; the outlet pipe 6 is equipped with 6 baffles 8, the baffles are 300mm×80mm×5mm (length×width×thickness), made of 316L stainless steel, staggered (the distance between adjacent plates is 80mm), tilted downward at an angle of 35°, and the edges are fully welded to the inner wall of the outlet pipe.

[0021] Control valve 9, model ZJHP-16C, is a pneumatic diaphragm single-seat control valve with a nominal diameter of DN50 and a stainless steel seat. Its adjustment range is 0-100%, and its operating pressure is 0.14-0.4 MPa. Flow meter 10, model LUGB-25, is a vortex flow meter with a measurement range of 100-1000 Nm. 3 / h, accuracy ±1.5%, medium temperature -20-120℃, pressure 0.1-1.0MPa; differential pressure gauge 11 model 3051CD, differential pressure transmitter, measuring range 0-10kPa, accuracy ±0.075%, output signal 4-20mA; PLC controller model S7-1200 (CPU1214C), equipped with analog input module SM 1231 (4 channels), digital output module SM 1222 (8 channels), power supply voltage 220VAC.

[0022] The adsorption tower outlet pipe 5 is a seamless 304 stainless steel pipe, DN80, with a wall thickness of 5mm; the dust collector outlet pipe 7 is a seamless 304 stainless steel pipe, DN65, with a wall thickness of 4mm; all pipe connections use GB / T 9119-2010 standard flat welding flanges, made of 304 stainless steel, with a nominal pressure of 1.0MPa; the fluororubber (FKM) gaskets used are resistant to temperatures of -20-150℃ and resistant to vinyl chloride corrosion; the bolts used are GB / T 5782-2016 standard 304 stainless steel bolts, with specifications of M20×80mm, and matching nuts and flat washers.

[0023] The connection relationship and specific working process of this utility model are as follows: I. Connection Relationship 1. The outlet flange of adsorption tower 1 is fastened to one end of the outlet pipe 5 of adsorption tower by M20×80mm stainless steel bolts, and a fluororubber gasket is installed between the flanges. The other end of the pipe is connected to the inlet flange of buffer tank 3 in the same way.

[0024] 2. A regulating valve 9 is welded and installed in the middle section of the outlet pipe 5 of the adsorption tower. DN80 stainless steel flanges are installed before and after the regulating valve and fixed to the pipe flanges with bolts. The sealing gasket is made of fluororubber.

[0025] 3. The flow meter 10 is fixed to the top flange of the buffer tank 3 with bolts. The measuring end of the flow meter is inserted into the tank 150mm, and the installation angle is vertical. The seal uses the manufacturer's matching fluororubber sealing ring.

[0026] 4. The outlet flange of buffer tank 3 is connected to the inlet flange of dust collector 4. DN65 stainless steel pipe and matching flanges, bolts and fluororubber gaskets are used. After connection, an airtightness test is carried out (test pressure 0.8MPa, pressure held for 30min without leakage). 5. The outlet pipe 6 of the dust collector 4 is welded to the outlet pipe 7 of the dust collector (the welding method is argon arc welding, the weld height is 5mm, and there are no pores or slag inclusions). The other end of the pipe is bolted to the inlet flange of the preheater 2, and the sealing method is the same as before.

[0027] 6. A differential pressure gauge 11 is installed on the top flange of the dust collector 4. The measuring interface is welded to both sides of the dust collector shell (300mm apart). The differential pressure gauge is connected through a Φ14 stainless steel pressure guide tube. Both ends of the pressure guide tube are sealed with compression fittings.

[0028] 7. The signal cables (shielded twisted pair) of regulating valve 9, flow meter 10, and differential pressure gauge 11 are connected to the analog input module of the PLC controller. The PLC output signal cable is connected to the pneumatic actuator of the regulating valve. The cables are protected by Φ20 stainless steel conduit and fixed at 1.5m intervals.

[0029] II. Work Process 1. Control Logic The PLC controller acquires the gas flow signal from flow meter 10 and the differential pressure signal across the dust collector from differential pressure gauge 11 in real time. When the flow rate is below 500 Nm³ / h... 3 When the flow rate is / h, the PLC output signal increases the opening of regulating valve 9; when the flow rate is higher than 800Nm 3 When the flow rate is / h, reduce the opening of the regulating valve to maintain the flow rate within the set range. When the differential pressure gauge 11 detects a value exceeding 8kPa, the PLC triggers an alarm signal (the on-site audible and visual alarm is activated), indicating that the dust collector needs to be cleaned.

[0030] 2. Work Process The vinyl chloride recovery gas (containing a small amount of molecular sieve powder, pressure 0.3-0.6MPa, temperature 40-60℃) discharged from adsorption tower 1 flows through adsorption tower outlet pipe 5 and regulating valve 9; the gas enters buffer tank 3, where the pressure fluctuation is reduced by the internal space (fluctuation range ≤ ±0.02MPa), and flow meter 10 monitors the gas flow in real time and feeds it back to PLC; the stabilized gas enters dust collector 4, where the airflow is blocked by baffle plate 8 and turns multiple times. The molecular sieve powder settles to the bottom of the dust collector after impacting the baffle plate due to inertia (periodically discharged through the bottom drain port); the clean vinyl chloride gas after dust removal enters preheater 2 through outlet pipe 6 and dust collector outlet pipe 7, where it exchanges heat with 120℃ saturated steam and is heated to 80-90℃, and then sent to the subsequent vinyl chloride synthesis process.

[0031] Throughout the process, the PLC controller maintains stable system flow and pressure by interlocking the regulating valve 9, while the differential pressure gauge 11 monitors the dust collector blockage in real time.

Claims

1. A vinyl chloride pressure swing adsorption dust removal device, comprising an adsorption tower (1), a preheater (2), and an adsorption dust removal system disposed between the adsorption tower (1) and the preheater (2), characterized in that, The adsorption dust removal system includes a buffer tank (3) and a dust collector (4); the outlet of the adsorption tower (1) is connected to the inlet of the buffer tank (3) through the adsorption tower outlet pipe (5), the outlet of the buffer tank (3) is connected to the inlet of the dust collector (4), and the outlet pipe (6) of the dust collector (4) is connected to the inlet of the preheater (2) through the dust collector outlet pipe (7).

2. The adsorption dust removal device as described in claim 1, characterized in that, The outlet pipe (6) is provided with multiple baffles (8), which are staggered on the inner wall of the outlet pipe (6) and are all inclined downwards.

3. The adsorption dust removal device as described in claim 1, characterized in that, The adsorption tower outlet pipe (5) is equipped with a regulating valve (9), and the buffer tank (3) is equipped with a flow meter (10). The regulating valve (9) and the flow meter (10) are interlocked and used together.

4. The adsorption dust removal device as described in claim 3, characterized in that, The dust collector (4) is equipped with a differential pressure gauge (11).

5. The adsorption dust removal device as described in claim 4, characterized in that, The regulating valve (9), flow meter (10), and differential pressure gauge (11) are all connected to the PLC controller.

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