A suspension process for the collinear production of chlorinated polyvinyl chloride and chlorinated polyethylene

Abstract

The application discloses a kind of chlorinated polyvinyl chloride and chlorinated polyethylene suspension method collinear production system, including shared equipment and special equipment.Shared equipment includes raw material sealed conveying system, batching kettle, suspension dosing system, additive dosing system, chlorination reaction kettle, post-processing unit, centrifugal equipment, post-packaging line, hydrochloric acid recovery unit, secondary alkali washing system, chlorine supply unit and DCS control system;Special equipment includes raw material bin A / B, nitrogen supply unit, mixing tank A / B, drying system A / B, finished product bin A / B, packaging machine A / B and mixer.DCS control system stores process step A for producing chlorinated polyvinyl chloride by suspension method and process step B for producing chlorinated polyethylene, one-key switching control shared equipment and special equipment work together, realize the production of two products.The application reduces equipment investment and floor area, avoids product cross-contamination, realizes by-product hydrochloric acid resource recycling, one-key switching improves convenience and controllability.

Description

Technical Field

[0001] This invention relates to the technical field of chlorinated polyvinyl chloride and chlorinated polyethylene production equipment, specifically to a suspension co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene. Background Technology

[0002] The production of chlorinated polyvinyl chloride mainly adopts solvent method, gas-solid phase method and traditional two-stage chlorination process, while the production of traditional chlorinated polyethylene mainly adopts aqueous suspension process.

[0003] In existing technologies, the production processes of chlorinated polyvinyl chloride (PVC) and chlorinated polyethylene (PE) are independent, requiring two complete sets of production equipment (raw material preparation, chlorination, post-treatment, etc.). This results in high equipment investment, large footprint, and high energy consumption. Furthermore, the byproduct acid from the two systems cannot be recycled and reused in a coordinated manner, leading to poor environmental and economic benefits. Directly integrating the two sets of equipment (one system for the production of both products) presents several challenges. First, the lack of dedicated equipment for each product makes cross-contamination highly likely, affecting product quality stability. Second, the resource recycling of byproduct hydrochloric acid cannot be achieved. Most importantly, product switching is cumbersome, requiring changes to raw materials, batching, and parameters. Adjusting parameters, in particular, is time-consuming, labor-intensive, and prone to errors, highlighting the need for improved convenience and controllability. Summary of the Invention

[0004] Therefore, embodiments of the present invention provide a co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, in order to solve one or more of the aforementioned technical problems.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A suspension chlorination system adaptable to the production of chlorinated polyvinyl chloride (PVC) and chlorinated polyethylene (PE), with flexible suspension options, diverse initiation methods, recycling of by-product hydrochloric acid, environmental friendliness and low consumption, excellent product heat resistance and stability, and fully automated process control, is characterized by the fact that PVC and PE preparation share a single production system (therefore, this system is also called: a PVC and PE suspension co-production system). This production system is divided into shared equipment (system) and dedicated equipment (system), and flexible switching between the two products can be achieved by adjusting the raw materials, initiation system parameters, and chlorination reaction stage parameters.

[0007] I. Production System Configuration

[0008] Core shared equipment includes: closed raw material conveying system, batching kettle, chlorination reactor, post-processing unit (also known as post-processing system), slurry conveying pump, centrifugal equipment (also known as centrifuge, centrifugal dewatering equipment, centrifugal deacidification and dewatering equipment), and post-packaging line (also known as shared conveying line).

[0009] Product-specific units (dual-branch product isolation design to avoid cross-contamination throughout the process): Raw material silo A (referring to PVC-specific raw material silo), raw material silo B (referring to PE-specific raw material silo); two sets of mixing tanks A and B for the drying workshop, two sets of independent and dedicated drying systems A and B, two finished product silos A and B for finished products, and two sets of independent packaging machines A and B; among which, the CPE branch is equipped with a dedicated mixing machine.

[0010] All shared auxiliary systems include: hydrochloric acid recovery unit, two-stage alkaline washing system, and DCS control system (also known as DCS fully automatic control system, DCS system, or simply DCS).

[0011] The hydrochloric acid recovery unit includes sedimentation filtration equipment, hydrochloric acid storage tank, and optional falling film absorber (also known as falling film absorption device) and deep desorption system (also known as deep desorption device).

[0012] Sedimentation and filtration equipment is a basic and essential piece of equipment. It is used to purify and remove impurities from the crude by-product hydrochloric acid separated from the reaction. The qualified hydrochloric acid is sent to a storage tank for temporary storage and can be directly reused in the batching suspension system.

[0013] The falling film absorber and the deep anaerobic digester are two independent optional process modules. You can choose one of them or combine them as needed, depending on your production requirements and product export plans.

[0014] Optional falling film absorber: used to absorb and concentrate dilute hydrochloric acid to produce high-concentration commercial hydrochloric acid for external sale.

[0015] Optional deep-analysis system: used to analyze and recover hydrogen chloride gas from hydrochloric acid, and to return the low-concentration residual acid after analysis to the storage tank for reuse in batching.

[0016] Hydrochloric acid storage tanks: divided into concentrated acid storage tanks and reusable dilute acid storage tanks, which store filtered purified hydrochloric acid and desorbed dilute acid respectively, and supply them to the batching tank as raw materials for suspension.

[0017] II. Raw Materials and Suspension System

[0018] Shared suspension system: water, desalinated water or dilute hydrochloric acid (all from hydrochloric acid recovery unit reuse), with the system weight solids content controlled at 20%~30%.

[0019] Common initiation system: Photoinitiation, chemical initiation, thermal initiation, or a combination of initiation can be used. Chemical initiators include benzoyl peroxide, and dispersants are selected from polyvinyl alcohol, silica sol, sodium polymethacrylate, etc. Based on the weight of the main material, the initiator addition is 0.01%~1.5%, and the dispersant addition is 0.05%~5% (both products are interchangeable; no change in additive type is required, only slight adjustments in dosage).

[0020] Raw material switching: When producing chlorinated polyvinyl chloride, the main material is polyvinyl chloride resin; when producing chlorinated polyethylene, the main material is switched to polyethylene powder. The raw materials are accurately transported to the batching tank through a shared closed raw material conveying system (ton bag breaking, pneumatic conveying, metering), without the need to change the conveying equipment.

[0021] III. Ingredients and Emulsification

[0022] Both products share the same batching tank and mixing equipment, and the process is completely identical: first, a suspension is added to the batching tank, and then the initiator and dispersant are precisely added through a shared additive dosing system (quantitative preparation, high-precision metering pump, and mass flow meter closed-loop calibration). After standing, the corresponding main material (polyvinyl chloride / polyethylene) is added, and the mixture is stirred and emulsified for 0.5 hours to form a uniform and stable suspension system, which is then directly transported to a shared chlorination reactor without the need to adjust the equipment or process.

[0023] IV. Chlorination reaction

[0024] Both products share the same chlorination reactor. By switching process parameters through the DCS system, independent chlorination of each product can be achieved without changing the reaction equipment.

[0025] Chlorinated polyvinyl chloride chlorination process (i.e., process step A)

[0026] After the suspension is transferred from the batching vessel to the chlorination reactor, nitrogen is used for purging and deoxygenation for 25 minutes. The system automatically heats up to 70-80℃ and stirring is started. Temperature and chlorination are controlled in six stages: ① First stage: nitrogen removal stage. Chlorination rate is 2-4 kg / min, chlorination is carried out for 6-8 minutes to remove nitrogen, and the tail gas valve is closed; ② Second stage: control the chlorination rate at 3-5 kg / min, reactor pressure at 0.05-0.1 MPa, and reactor temperature at 90-95℃; ③ Third stage: control the chlorination rate at 4-9 kg / min, reactor pressure at 0.1-0.13 MPa, and reactor temperature at 95-99℃; ④ Fourth stage: control the chlorination rate at 4-7 kg / min, reactor pressure at 0.13-0.18 MPa, and reactor temperature at 99-101℃; ⑤ Fifth stage: control the chlorination rate at 2-6 kg / min, reactor pressure at 0.18-0.23 MPa, and reactor temperature at 101-105℃. ⑥ Sixth stage: Stop chlorination when the total chlorine flow reaches 105%~115% of the theoretical chlorine consumption. At this time, the maximum pressure of the reactor is controlled at 0.27MPa, and the reactor temperature is finally controlled at 115℃. Then, immediately force rapid cooling and pressure reduction. When the reactor pressure drops to 0.05MPa, open the tail gas valve to discharge the residual chlorine, and the material is discharged into the common post-treatment unit.

[0027] Chlorinated polyethylene chlorination process (i.e., process step B)

[0028] The suspension is transferred from the batching vessel to the same chlorination reactor. The tail gas is vented, the temperature is increased, and oxygen is removed. The system automatically heats up to the initial reaction temperature of 70℃, then the tail gas valve is closed, and chlorination begins. Temperature and chlorination are controlled in three stages: ① Low-temperature initiation stage (70~90℃): chlorination rate 2~5 Kg / min, reactor pressure 0.05~0.15 MPa; ② Main reaction stage (95~110℃): chlorination rate 3~7 Kg / min, reactor pressure 0.15~0.25 MPa; ③ High-temperature homogenization and chlorination replenishment stage (115~130℃): chlorination rate 1~3 Kg / min, reactor pressure 0.20~0.30 MPa.

[0029] Endpoint control: After the target chlorine content is reached, chlorination is stopped, the maximum pressure in the reactor is controlled at 0.30 MPa, the reactor temperature is ultimately controlled at 130℃, and then automatically cooled down to 70℃. Compressed air is used to pressurize the material to the common post-processing unit.

[0030] V. Post-processing

[0031] Both products share a single post-processing system, combined with dedicated units for each product. The process is standardized and prevents cross-contamination, as follows: Materials pass through a shared concentrated acid filter to separate hydrochloric acid. The filter cake then enters a shared soaking tank for thorough deacidification. After passing through shared post-processing equipment, the filter cake enters a shared transfer tank where water is added in a set ratio to prepare the slurry. The prepared slurry is then pumped by a shared slurry pump and splits into two branches, entering two dedicated mixing tanks, A (for CPVC) and B (for CPE), in the drying workshop. This separate mixing of the two slurries avoids cross-contamination. The mixed slurries are then pumped separately into a shared centrifuge for batch-by-batch centrifugation. The centrifuged cakes are then transported to two dedicated drying systems, A (for CPVC) and B (for CPE), for independent drying, ensuring stable product quality.

[0032] VI. Finished Product Packaging

[0033] After drying, the two finished products enter their respective dedicated finished product silos A (CPVC) and B (CPE): chlorinated polyvinyl chloride is directly fed from silo A into the receiving hopper of dedicated packaging machine A for packaging; chlorinated polyethylene is fed from silo B into a dedicated mixer, where a release agent (to prevent clumping) is added and the mixture is thoroughly mixed before being conveyed to the receiving hopper of dedicated packaging machine B for packaging. The bagged materials packaged by both machines (Machine A and Machine B) then enter a shared post-packaging line, sequentially undergoing metal detection, re-weighing, coding (to label product information), and palletizing processes. This achieves efficient and standardized packaging for both products without requiring additional conveying and post-packaging equipment, balancing packaging efficiency and product traceability.

[0034] VII. By-product hydrochloric acid recovery and tail gas treatment

[0035] The hydrochloric acid byproducts from the production processes of CPVC and CPE are centrally processed in a shared hydrochloric acid recovery unit. This unit is equipped with standard sedimentation filtration equipment and hydrochloric acid storage tanks of various specifications. Falling film absorbers and deep-penetration systems are optional advanced processing modules that can be flexibly selected based on the company's external sales and raw material reuse needs. The overall system achieves graded storage, multi-path resource utilization, and closed-loop reuse of byproduct hydrochloric acid.

[0036] 1. Hydrochloric acid purification process: The by-product hydrochloric acid separated by the concentrated acid filter after chlorination is first sent to the sedimentation filter to complete the removal and purification of impurities. The qualified hydrochloric acid after purification is transported to the storage tank for temporary storage in designated areas.

[0037] 2. Zoned storage of storage tanks: Two types of storage tanks are set up: concentrated acid storage tanks and reusable dilute acid storage tanks. The concentrated acid storage tanks store concentrated hydrochloric acid purified by sedimentation and filtration, while the reusable dilute acid storage tanks collect low-concentration residual acid produced by the deep analysis system. The acid in both types of storage tanks can be directly transported to the batching kettle and recycled as raw material for the suspension system.

[0038] 3. Optional deep processing paths (choose one or a combination)

[0039] (1) Select a falling film absorber: further absorb and concentrate the low-concentration dilute hydrochloric acid in the storage tank to prepare high-concentration commercial hydrochloric acid for external sale, thereby increasing the additional income from by-products;

[0040] (2) Select deep analysis system: analyze the hydrochloric acid in the storage tank, separate and recover hydrogen chloride gas, which can be reused in the chlorination reaction. After the analysis is completed, the low concentration of residual acid generated is returned to the reuse dilute acid storage tank to continuously prepare suspension.

[0041] Each ton of product can produce 1 to 1.2 tons of by-product hydrochloric acid. After being processed by the above system, there is no waste acid discharge, realizing the full recycling or resource-based sale of the by-product acid.

[0042] The exhaust gases generated from the chlorination reaction of the two types of products are uniformly fed into a shared two-stage alkaline scrubbing system for centralized treatment. After the residual chlorine is absorbed by the two-stage alkaline scrubbing, the exhaust gases are discharged after meeting the standards, eliminating the need for separate exhaust gas treatment equipment for the two types of products.

[0043] VIII. System Control

[0044] The entire production system adopts a DCS fully automated control system, which presets two production parameter modes: chlorinated polyvinyl chloride (process step A) and chlorinated polyethylene (process step B). When switching products, it is only necessary to call the corresponding parameter mode in the DCS system to automatically adjust the parameters of each link such as batching, chlorination, post-treatment, slurry preparation, drying, and packaging without much manual intervention. At the same time, it realizes full automation of raw material metering, auxiliary agent addition, temperature and pressure control, tail gas treatment, hydrochloric acid recovery, and finished product packaging, ensuring stable and reliable production. Moreover, the production data of the two products can be recorded and traced separately.

[0045] IX. Overall System Layout

[0046] The production system of this invention is arranged horizontally according to the production flow of "raw material transportation → batching → chlorination reaction → post-processing → finished product packaging". The auxiliary shared system is arranged vertically on the right side of the overall system, forming a neat, continuous, and non-interfering structural layout. The core design is "one set of shared core equipment + dual raw material / dual finished product dedicated units", which realizes flexible switching between the production of chlorinated polyvinyl chloride and chlorinated polyethylene. All shared equipment is made of acid and corrosion resistant materials and is adapted to the production conditions of the two products. The dedicated units are only used for product differentiation processing and do not require additional complete sets of production equipment.

[0047] 10. Connection Relationships of Various Structures

[0048] 1. Raw material storage and conveying unit (product switching start point): Two independent raw material silos are set up, namely raw material silo A (polyvinyl chloride resin silo) and raw material silo B (polyethylene powder silo). The bottom of the two silos shares a set of closed raw material conveying system. The two raw materials can be accurately metered and conveyed to the common batching tank by switching conveying paths, so as to realize the switching supply and accurate conveying of raw materials without the need to equip two separate conveying systems.

[0049] 2. Batching Unit (Shared Throughout): One shared batching vessel is installed, equipped with stirring equipment. A shared additive dosing system is connected to one side of the batching vessel. This system includes an initiator preparation vessel, a dispersant preparation vessel, a metering storage tank, a high-precision metering pump, and a mass flow meter, which can realize the quantitative preparation and precise dosing of additives. The raw material conveying pipeline is connected to the raw material inlet of the shared batching vessel at its end. The additive dosing system is connected to the additive inlet of the batching vessel through a pipeline, forming a mixed emulsion structure of "suspension + additive + main material". The batching process of the two products is completely consistent, and the switching is achieved only by adjusting the type of main material.

[0050] 3. Chlorination Reaction Unit (Shared throughout, core unit): A shared enamel-lined chlorination reactor is installed, equipped with a jacketed heating / cooling device, stirring device, and temperature and pressure monitoring device. The inlet of the chlorination reactor is connected to the outlet of the shared batching reactor via pipeline to receive the suspension system delivered by the batching unit. A DCS control interface is installed on one side of the reactor, connected to the shared DCS fully automatic control system. By switching parameter modes (process step A or process step B), differentiated chlorination reactions for two products can be achieved without changing the reaction equipment. The temperature and pressure parameters during the reaction process are monitored and controlled in real time by the DCS system.

[0051] 4. Post-processing unit (shared core equipment + dedicated sub-tank unit): Following the production flow, a shared concentrated acid filter, shared soaking tank, shared post-processing equipment, shared transfer tank, and shared slurry pump are sequentially set up. These devices are connected in series via pipelines. The discharge port of the post-processing equipment is connected to the inlet of the transfer tank. The transfer tank is equipped with a slurry mixing device, which can add water according to a set ratio to achieve filter cake slurry mixing. The discharge port of the slurry pump is divided into two branches, connecting to two dedicated drying workshop mixing tanks A (CPVC dedicated) and B (CPE dedicated), respectively, to achieve separate mixing of the two slurries and avoid cross-contamination. The discharge ports of the two dedicated mixing tanks A / B are each connected to a shared centrifuge via pipelines. The discharge port of the centrifuge is divided into two branches, connecting to two dedicated drying systems A (CPVC dedicated) and B (CPE dedicated), respectively, to achieve independent drying of the centrifuged cake and ensure stable quality of both products.

[0052] 5. Finished product packaging unit (dedicated unit + shared post-packaging line): Two independent finished product silos, A (CPVC) and B (CPE), are set up. The inlets of the two silos are connected to the outlets of the corresponding dedicated drying systems A and B, respectively, to receive the dried finished products. The outlet of finished product silo A is directly connected to the receiving hopper of a dedicated packaging machine, which is connected to dedicated packaging machine A to achieve direct packaging of chlorinated polyvinyl chloride (CPVC) finished products. The outlet of finished product silo B is connected to a dedicated mixer equipped with a release agent addition device. The outlet of the mixer is connected to the receiving hopper of a dedicated packaging machine, which is connected to dedicated packaging machine B to achieve packaging of chlorinated polyethylene (CPE) finished products after the addition of a release agent. The outlets of both packaging machines (packaging machines A and B) are connected to a shared post-packaging line. The shared post-packaging line is equipped with metal detection equipment, a re-inspection scale, a coding device, and a palletizing device in sequence. The packaged bagged materials undergo metal detection, weight re-inspection, product coding, and automatic palletizing in sequence through the shared post-packaging line, achieving efficient and standardized packaging of both products without the need for additional conveying and post-packaging equipment, thus balancing packaging efficiency with product quality control and traceability.

[0053] 6. Auxiliary shared system (vertically arranged, fully adaptable):

[0054] (1) Shared hydrochloric acid recovery unit: The system is equipped with sedimentation filtration equipment and zoned mixing storage tanks as standard. Falling film absorbers and deep desorption systems are independent optional deep processing modules that can be selected as needed and are not mandatory. The material relationship of the equipment is divided into three levels of logic: pre-purification series branch, optional deep processing parallel branch, and reuse closed-loop pipeline.

[0055] ① Pre-purification series link: After the by-product hydrochloric acid from the concentrated acid filter and the deacidification centrifuge is collected, it is first connected in series into the sedimentation filter to remove solid impurities. The purified hydrochloric acid is then transported to the partitioned mixing and storage tank for temporary storage (divided into concentrated acid storage area and reuse dilute acid storage area).

[0056] ② Optional parallel branch for deep processing: Two parallel pipelines that do not interfere with each other are led out from the mixing and storage tank, respectively connecting to the optional falling film absorber and deep desorption system. Enterprises can choose one of them individually according to their export or hydrogen chloride recovery needs, or they can use both sets at the same time.

[0057] 1) If a falling film absorber is selected: the dilute hydrochloric acid in the tank is concentrated to produce high-concentration commercial hydrochloric acid, and the remaining dilute acid after concentration is returned to the mixing and storage tank.

[0058] 2) If a deep desorption system is selected: the hydrogen chloride gas separated by desorption is reused in the chlorination process, and the low-concentration residual acid after desorption is transported to the reuse dilute acid storage area of ​​the mixing storage tank.

[0059] ③ Reuse closed-loop pipeline: The mixing and storage tank is connected to the suspension inlet of the common batching vessel through a dedicated conveying pipeline. The purified concentrated hydrochloric acid and the dilute acid after desorption in the tank can be directly conveyed to the batching vessel for use as a suspension medium, thus forming a complete closed loop for the recovery, deep processing and reuse of by-product hydrochloric acid.

[0060] The entire recycling system connects to the hydrochloric acid outlets of the concentrated acid filter and centrifuge respectively through two feed pipelines for unified collection. A single system can simultaneously handle the by-product hydrochloric acid from both CPVC and CPE products, making it suitable for dual-product shared production line conditions.

[0061] (2) Shared tail gas two-stage alkaline washing system: including a primary alkaline washing tower and a secondary alkaline washing tower, which are connected to the tail gas outlet of the shared chlorination reactor through pipelines to treat the tail gas generated during the reaction process, ensuring that the tail gas meets the emission standards, without the need to set up a separate tail gas treatment device.

[0062] (3) DCS fully automatic control system: It is located at the top of the auxiliary system and is connected to the control components of all common equipment (batching kettle, chlorination reactor, slurry pump, common centrifuge equipment, hydrochloric acid recovery unit, secondary alkaline washing system, etc.) and special units through multiple control lines. It presets two production parameter modes (process steps A / B) for two products, and can realize full-process automatic control, product parameter switching and production data recording and traceability.

[0063] The embodiments of the present invention have the following advantages:

[0064] 1. Enables shared use of a single production line, significantly reducing costs.

[0065] Chlorinated polyvinyl chloride and chlorinated polyethylene share a core production system (batching tank, chlorination reactor, post-processing unit, centrifuge equipment) and auxiliary systems (hydrochloric acid recovery unit, secondary alkaline washing system, DCS control system), eliminating the need for two separate sets of equipment. This reduces equipment investment by more than 60%, floor space by 40%, and energy consumption by 30%, significantly improving production economics.

[0066] 2. Convenient product switching and high production efficiency.

[0067] By switching parameter modes (process steps A / B) through the DCS control system, the production switch between the two products can be completed without downtime or equipment modification. The switchover time is short, and the output of the two products can be flexibly adjusted according to market demand.

[0068] 3. Optimized post-processing procedures ensure stable product quality.

[0069] An intermediate slurry preparation and mixing tank (mixing tank A / B) is added, along with a dedicated drying system A / B, to avoid cross-contamination between the two products. A mixer is added to chlorinated polyethylene to mix the release agent, preventing the finished product from clumping and ensuring the stable quality of chlorinated polyvinyl chloride (chlorine content 66~70%, excellent thermal stability) and chlorinated polyethylene (uniform particles, low impurities, no clumping).

[0070] 4. Resource utilization of by-product hydrochloric acid

[0071] Each ton of product produces 1-1.2 tons of hydrochloric acid as a byproduct. After purification by the hydrochloric acid recovery unit (sedimentation filtration equipment, hydrochloric acid storage tank), it can be reused in the suspension dosing system to provide a suspension medium for the batching tank. Alternatively, a falling film absorber can be added to concentrate the acid for external sale or a deep desorption system can be used to recover hydrogen chloride. All dilute acid is reused, providing a rich resource utilization pathway and solving the problem of byproduct acid disposal.

[0072] 5. Environmentally friendly and low-consumption

[0073] There is no organic solvent pollution, the wastewater volume and salt content are greatly reduced, the tail gas is discharged in compliance with standards after passing through a two-stage alkaline scrubbing system (first-stage alkaline scrubbing tower + second-stage alkaline scrubbing tower), and the by-product acid is fully recycled, which meets the requirements of clean production.

[0074] 6. Safe and reliable

[0075] The entire process is automated, reducing manual operation. Multiple interlock protections for temperature, pressure, liquid level, and chlorine flow are set up to prevent runaway reactions, ensuring high safety in the production of both products.

[0076] 7. Packaging process is highly adaptable and efficient.

[0077] Differentiated packaging processes are designed for the characteristics of the two products. Two dedicated packaging machines, A and B, are configured to adapt to the packaging of the two products respectively. After packaging, the metal detection, re-inspection, coding and palletizing are completed in an integrated process through a shared post-packaging line. No additional conveying and post-packaging equipment is required, which takes into account packaging efficiency, product storage stability and quality control. Attached Figure Description

[0078] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0079] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0080] Figure 1 This is a schematic diagram of a co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, provided in an embodiment of the present invention.

[0081] Figure 2 This is a schematic diagram of the closed-loop raw material conveying system of a co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, provided in an embodiment of the present invention.

[0082] Figure 3 This is a schematic diagram of the additive dosing system of a suspension co-production system for chlorinated polyvinyl chloride and chlorinated polyethylene provided in an embodiment of the present invention;

[0083] Figure 4 This is a schematic diagram of the post-processing unit of a co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, provided in an embodiment of the present invention.

[0084] Figure 5 This is a schematic diagram of the hydrochloric acid recovery unit in a co-line production system of chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, provided in an embodiment of the present invention.

[0085] Figure 6A schematic diagram of the structure of a secondary alkaline washing system in a co-line production system of chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, provided in an embodiment of the present invention;

[0086] Figure 7 The diagram shows the electrical control principle of a co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, as provided in an embodiment of the present invention.

[0087] In the diagram: 1. Closed raw material conveying system; 101. Ton bag breaking machine; 102. Pneumatic conveying pipeline; 103. Metering auger; 2. Batching kettle; 3. Suspension dosing system; 4. Additive dosing system; 401. Initiator preparation kettle; 402. Metering storage tank A; 403. Metering pump A; 404. Mass flow meter A; 405. Dispersant preparation kettle; 406. Metering storage tank B; 407. Metering pump B; 408. Mass flow meter B; 5. Chlorination reactor; 6. Post-processing unit; 601. Concentrated acid filter; 602. Immersion kettle; 603. Post-processing equipment; 604. Transfer kettle; 605. Slurry pump; 606. Slurry mixing device; 7. Centrifuge equipment; 8. 9. Post-packaging line; 9. Hydrochloric acid recovery unit; 901. Sedimentation filtration equipment; 902. Hydrochloric acid storage tank; 903. Falling film absorber; 904. Deep desorption system; 905. Concentrated acid storage tank; 906. Dilute acid storage tank; 10. Secondary alkaline washing system; 1001. Primary alkaline washing tower; 1002. Secondary alkaline washing tower; 11. Chlorine supply unit; 12. DCS control system; 13. Raw material silo A; 14. Raw material silo B; 15. Nitrogen supply unit; 16. Mixing tank A; 17. Mixing tank B; 18. Drying system A; 19. Drying system B; 20. Finished product silo A; 21. Finished product silo B; 22. Packaging machine A; 23. Mixer; 24. Packaging machine B. Detailed Implementation

[0088] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0089] like Figure 1 and 7 As shown, this embodiment provides a co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, including shared equipment and dedicated equipment;

[0090] The shared equipment includes a closed raw material conveying system 1, a batching tank 2, a suspension dosing system 3, an auxiliary agent dosing system 4, a chlorination reactor 5, a post-processing unit 6, a centrifuge 7, a post-packaging line 8, a hydrochloric acid recovery unit 9, a secondary alkaline washing system 10, a chlorine supply unit 11, and a DCS control system 12.

[0091] The special equipment includes raw material silo A13, raw material silo B14, nitrogen supply unit 15, mixing tank A16, mixing tank B17, drying system A18, drying system B19, finished product silo A20, finished product silo B21, packaging machine A22, mixing machine 23, and packaging machine B24.

[0092] The raw material silos A13 and B14 are respectively connected to the closed raw material conveying system 1. The closed raw material conveying system 1, the batching tank 2, the chlorination reactor 5, and the post-processing unit 6 are connected in sequence. The suspension addition system 3 and the auxiliary agent addition system 4 are respectively connected to the batching tank 2. The chlorine supply unit 11 is connected to the chlorination reactor 5. The nitrogen supply unit 15 is connected to the chlorination reactor 5. The post-processing unit 6 is connected to the mixing tank A16 and the mixing tank B17. The mixing tank A16 and the mixing tank B17 are respectively connected to the centrifuge 7. The centrifuge 7 is respectively connected to the drying system A18 and the drying system B19. The drying system A18, the finished product silo A20, and the packaging machine A22 are connected in sequence. B19, finished product silo B21, mixer 23, and packaging machine B24 are connected in sequence. Packaging machines A22 and B24 are respectively connected to the post-packaging line 8. The hydrochloric acid recovery unit 9 is respectively connected to the post-processing unit 6 and centrifuge 7. The secondary alkaline washing system 10 is respectively connected to the batching tank 2, chlorination reactor 5, and post-processing unit 6. The DCS control system 12 is electrically connected to the shared equipment and the special equipment. The DCS control system 12 is used to: store process step A for the suspension production of chlorinated polyvinyl chloride; process step B for the suspension production of chlorinated polyethylene; and, according to the product selection instruction, call the corresponding process step A or process step B, and control the shared equipment and the special equipment to work together to produce chlorinated polyvinyl chloride or chlorinated polyethylene by suspension.

[0093] This allows the production unit, which has the largest investment and the largest footprint, to share resources for both products, avoiding the duplication of large-scale equipment such as reactors, post-processing equipment 603, and acid recovery systems, thus reducing costs. By designating raw material silos A / B, mixing tanks A / B, drying systems A / B, finished product silos A / B, and packaging machines A / B as dedicated equipment, physical isolation of the two products is achieved at the four key nodes most prone to cross-contamination: raw material supply, slurry mixing, drying, and finished product packaging. The mixing tanks A / B are located after the post-processing unit 6 and before the centrifuge 7, ensuring that the slurries of the two products are completely separated before entering the shared centrifuge. This guarantees that even when sharing the centrifuge 7, cross-contamination will not occur due to the isolation of the mixing tanks and the batch centrifugation operation.

[0094] The DCS control system 12 controls the entire process parameters of the two products through process steps A and B respectively, and supports one-click switching. Operators do not need to adjust parameters for each piece of equipment. They only need to select the product type on the DCS interface, and the system automatically completes all operations such as switching the raw material selection path (activating raw material silo A13 or B), adjusting the dosage of additives (according to the product formula), converting the temperature and pressure parameters of the chlorination reaction (six-stage gradient chlorination or three-stage temperature and pressure controlled chlorination), adjusting the post-treatment slurry ratio, and switching the packaging method (activating the mixer 23 on the CPE branch). This transforms product switching from "cumbersome and error-prone manual operation" to "one-click automated control", greatly improving the convenience and controllability of production and ensuring the consistency of product quality from the software level.

[0095] The hydrochloric acid recovery unit 9 and the secondary alkaline washing system 10 are shared equipment, which enables the centralized treatment of by-product hydrochloric acid and chlorine-containing tail gas generated during the production of the two products. The by-product hydrochloric acid can be reused in the batching suspension system after unified recovery and purification, and the tail gas can be discharged in compliance with standards after secondary alkaline washing. This realizes the sharing and synergy of environmental protection facilities and avoids the repeated investment caused by equipping each production line with separate waste treatment devices.

[0096] like Figure 2 As shown, the closed raw material conveying system 1 includes a ton bag crusher 101, an air conveying pipe 102, and a metering auger 103. The discharge port of the ton bag crusher 101 is connected to the inlet of the air conveying pipe 102. The air conveying pipe 102 is connected to the inlets of the raw material silos A13 and B14 respectively through branches, and valves are respectively installed on the branch pipes. The discharge ports of the raw material silos A13 and B14 are respectively connected to the inlet of the metering auger 103. The discharge port of the metering auger 103 is connected to the inlet of the batching vessel 2.

[0097] Both raw material silos A13 (PVC resin) and B14 (PE powder) are dedicated silos, each equipped with a valve at its outlet. When producing CPVC, the valve in silo A13 is opened and the valve in silo B14 is closed; the reverse is true for CPE production. This simple valve switching allows for rapid switching of raw material sources. After being broken down by the silo breaker 101, the ton-bag raw materials are transported to the corresponding raw material silo via a fully enclosed pneumatic conveying pipe 102. The metered raw materials then enter the batching tank 2. The entire conveying process is isolated from the outside environment, preventing environmental pollution and raw material loss caused by dust leakage, and also preventing cross-contamination between the two raw materials during transport. The materials in the raw material silos are precisely metered by the metering auger 103 or a metering silo (which can also be used as a raw material silo) before being fed into the batching tank 2.

[0098] like Figure 3 As shown, the additive dosing system 4 includes an initiator preparation vessel 401, a metering storage tank A402, a metering pump A403, a mass flow meter A404, a dispersant preparation vessel 405, a metering storage tank B406, a metering pump B407, and a mass flow meter B408. The initiator preparation vessel 401, metering storage tank A402, and metering pump A403 are connected in sequence, and the dispersant preparation vessel 405, metering storage tank B406, and metering pump B407 are connected in sequence. The metering pumps A403 and B407 are respectively connected to the batching vessel 2 through pipelines. A mass flow meter A404 and a valve are respectively installed on the connecting pipeline between the metering pump A403 and the batching vessel 2, and a mass flow meter B408 and a valve are respectively installed on the connecting pipeline between the metering pump B407 and the batching vessel 2.

[0099] Initiators and dispersants are prepared and added separately using independent preparation kettles, metering tanks, and metering pumps. Each additive is independently metered and transported, avoiding cross-contamination during preparation and addition. Although the two products share the same additive addition equipment, the types and amounts of initiators and dispersants required for CPVC and CPE differ. Closed-loop calibration of the metering pump and mass flow meter (the mass flow meter provides real-time flow signal feedback to the DCS, and the DCS adjusts the metering pump frequency according to preset values) ensures precise control of the additive dosage after switching between different products, providing a material basis for the smooth progress of the chlorination reaction. The mass flow meter and valve settings provide the DCS control system 12 with precise execution terminals and data feedback sources. The DCS can compare the actual flow value fed back by the mass flow meter with the set value, and achieve closed-loop control by adjusting the metering pump frequency or valve opening, ensuring that the additive dosage is always within the target range. This is a crucial hardware support for the "one-click switching" function during the batching stage.

[0100] like Figure 4As shown, the post-processing unit 6 includes a concentrated acid filter 601, a soaking tank 602, a post-processing device 603, a transfer tank 604, and a slurry pump 605 connected in sequence. The inlet of the concentrated acid filter 601 is connected to the outlet of the chlorination reactor 5. The outlet of the slurry pump 605 is connected to the inlets of the mixing tank A16 and the mixing tank B17, respectively. Valves are respectively installed on the connecting pipes of the slurry pump 605 and the mixing tanks A16 and B17. The transfer tank 604 is equipped with a slurry mixing device 606.

[0101] After the chlorination reaction, the material is first separated into solid and liquid components by a concentrated acid filter 601. The separated byproduct hydrochloric acid is directly sent to the hydrochloric acid recovery unit 9, while the filter cake enters the soaking tank 602 for thorough deacidification and washing. Compared to a post-treatment process with only a single-stage filtration, this invention adds an soaking step to ensure that the residual hydrochloric acid in the filter cake is thoroughly washed away. This not only improves the recovery rate of byproduct hydrochloric acid (reducing acid loss with the filter cake) but also reduces the risk of acid corrosion to subsequent drying equipment, extending the equipment's service life.

[0102] The filter cake, after being filtered with concentrated acid and soaked and washed, enters the transfer vessel 604. Water is added according to a set ratio by the slurry mixing device 606 to remix the filter cake into a homogeneous slurry. On one hand, this redisperses the filter cake, which has unstable moisture content and is prone to clumping, into a homogeneous slurry with good flowability, facilitating subsequent pumping and centrifugal dewatering. On the other hand, the transfer vessel 604 serves as a buffer container between the post-treatment unit 6 and the drying unit, allowing the rhythm of the upstream post-treatment process and the downstream drying process to be independently adjusted, avoiding a complete line shutdown due to a short pause in one process. The homogenized slurry has a uniform solids content and good flowability, ensuring stable operation for subsequent centrifugal dewatering.

[0103] The discharge port of the slurry pump 605 is connected to mixing tank A16 (for CPVC) and mixing tank B17 (for CPE) via pipelines, and valves are installed on the connecting pipelines. By opening the corresponding valves, the prepared slurry can be selectively sent to mixing tank A16 or mixing tank B17 to achieve separate mixing of the two slurries and avoid cross-contamination.

[0104] As shown in Figure 5, the hydrochloric acid recovery unit 9 includes a sedimentation filtration device 901 and a hydrochloric acid storage tank 902. The hydrochloric acid outlets of the concentrated acid filter 601 and the centrifuge 7 are respectively connected to the inlet of the sedimentation filtration device 901. The outlet of the sedimentation filtration device 901 is connected to the inlet of the hydrochloric acid storage tank 902. The outlet of the hydrochloric acid storage tank 902 is connected to the inlet of the suspension dosing system 3.

[0105] The hydrochloric acid outlets of the concentrated acid filter 601 and centrifuge 7 are connected in parallel to the sedimentation filter 901. This allows for the centralized collection and unified treatment of two streams of by-product hydrochloric acid from different sources and concentrations, avoiding redundant investment in separate recovery equipment for each stream and maximizing the recovery rate of the by-product hydrochloric acid. The sedimentation filter 901 purifies the mixed hydrochloric acid, removing solid impurities. The purified hydrochloric acid, after being stored in the hydrochloric acid storage tank 902, can be directly reused in the suspension dosing system 3 as a feedstock suspension medium. The purified hydrochloric acid has a low impurity content, ensuring the purity of the chlorinated product and preventing process deterioration caused by the continuous accumulation of impurities in the acid circulation system. Each ton of product yields 1-1.2 tons of by-product hydrochloric acid, which is purified and reused, significantly reducing the consumption of fresh acid / water, achieving resource recycling, and reducing the environmental pressure of waste acid discharge.

[0106] like Figure 5 As shown, the hydrochloric acid recovery unit 9 further includes a falling film absorber 903 and / or a deep desorption system 904;

[0107] The hydrochloric acid storage tank 902 is a zoned mixing storage tank, including a concentrated acid storage tank 905 and a dilute acid storage tank 906. The hydrochloric acid outlets of the concentrated acid filter 601 and the centrifuge 7 are respectively connected to the concentrated acid storage tank 905.

[0108] The inlets of the falling film absorber 903 and / or the deep anaerobic digester 904 are respectively connected to the outlet of the concentrated acid storage tank 905, and the dilute acid outlets of the falling film absorber 903 and / or the deep anaerobic digester 904 are respectively connected to the inlet of the dilute acid storage tank 906.

[0109] The hydrochloric acid storage tank 902 is configured as a zoned mixing storage tank, including a concentrated acid storage tank 905 and a dilute acid storage tank 906, allowing for the separate storage of by-product hydrochloric acid of different concentrations. The concentrated hydrochloric acid can be directly reused in batching or sent to the falling film absorber 903 for concentration and sale, while the dilute hydrochloric acid can be centrally sent to the falling film absorber 903 for concentration or reused in processes with lower acid concentration requirements, thus achieving graded utilization of resources.

[0110] The falling film absorber 903, as an optional module, can further absorb and concentrate the dilute hydrochloric acid in the storage tank into high-concentration commercial hydrochloric acid for sale, thereby optimizing the economic efficiency of by-product acid disposal.

[0111] The deep analysis system 904, as another optional module, performs deep analysis on the hydrochloric acid in the concentrated acid storage tank 905, separates and recovers high-purity hydrogen chloride gas for reuse in the chlorination reaction, reducing the dependence of the chlorination reaction on external chlorine / hydrogen chloride raw materials. The low-concentration residual acid after analysis is returned to the dilute acid storage tank 906 and continues to be used for batching and suspension.

[0112] like Figure 6As shown, the two-stage alkaline washing system 10 includes a primary alkaline washing tower 1001 and a secondary alkaline washing tower 1002. The gas inlet of the primary alkaline washing tower 1001 is connected to the exhaust gas outlet of the batching vessel 2, the chlorination reactor 5, and the post-treatment unit 6. The exhaust gas outlet of the primary alkaline washing tower 1001 is connected to the gas inlet of the secondary alkaline washing tower 1002.

[0113] The exhaust outlets of the batching vessel 2, chlorination reactor 5, and post-treatment unit 6 are all connected to the primary alkaline scrubbing tower 1001, achieving unified collection and centralized treatment of chlorine-containing / acidic waste gas throughout the entire process. The two alkaline scrubbing towers operate in series. The primary alkaline scrubbing tower 1001 handles the main chlorine absorption load, while the secondary alkaline scrubbing tower 1002 deeply purifies the residual chlorine at the primary outlet, ensuring that the chlorine in the exhaust gas is fully absorbed. The chlorine content in the treated exhaust gas is far below the emission standard limits.

[0114] In this embodiment, process step A includes:

[0115] SA1. Nitrogen purging for deoxygenation and heating inside the reactor: After the suspension is transferred from the batching reactor 2 to the chlorination reactor 5, nitrogen is used to purge oxygen for more than 25 minutes. The system automatically heats up to 70~80℃ and stirring is started.

[0116] SA2, CPVC six-stage gradient chlorination;

[0117] SA21, chlorine is introduced to remove nitrogen. The chlorine rate is 2-4 kg / min. Chlorine is introduced for 6-8 minutes to remove nitrogen. Then, the tail gas valve is closed.

[0118] SA22, control the chlorination rate at 3~5 Kg / min, the pressure at the reactor at 0.05~0.1 MPa, and the reactor temperature at 90~95℃;

[0119] SA23, control the chlorination rate at 4~9 Kg / min, the pressure at the vessel at 0.1~0.13MPa, and the temperature at the vessel at 95~99℃;

[0120] SA24, control the chlorination rate at 4~7 Kg / min, the pressure at the vessel at 0.13~0.18 MPa, and the temperature at the vessel at 99~101℃;

[0121] SA25, control the chlorination rate at 2~6 Kg / min, the pressure at the vessel at 0.18~0.23 MPa, and the temperature at the vessel at 101~105℃;

[0122] SA26. When the total chlorine flow reaches 105%~115% of the theoretical chlorine consumption, stop the chlorine flow. At this time, the maximum pressure in the reactor is controlled at 0.27 MPa, and the reactor temperature is finally controlled at 115℃. Then, immediately force rapid cooling and depressurization. When the reactor pressure drops to 0.05 MPa, open the tail gas valve to discharge the residual chlorine, and discharge the material into the shared post-treatment unit 6.

[0123] Step SA1 involves nitrogen purging and deoxygenation for at least 25 minutes before chlorination to completely remove oxygen from the chlorination reactor 5. The chlorination reaction is carried out at high temperatures; if residual oxygen remains in the system, it may cause oxidative degradation of polyvinyl chloride (PVC) or form an explosive gas mixture in the presence of chlorine. Thorough nitrogen deoxygenation eliminates the safety hazard at its source and avoids the inhibitory effect of oxygen on the chlorination reaction (oxygen can consume free radicals or participate in side reactions), ensuring the smooth progress of the chlorination reaction.

[0124] Step SA2 meticulously divides the CPVC chlorination process into six stages (SA21, the nitrogen removal stage; and SA22-SA26, the five chlorination stages). The chlorination rate and reactor temperature and pressure are precisely controlled within specific ranges for each stage. The advantage lies in the fact that chlorination of polyvinyl chloride is an exothermic reaction, and the reactivity of the chlorination reaction gradually decreases as the chlorine content increases. Using a single chlorination condition would lead to a violent reaction and localized over-chlorination in the early stages, followed by a slow reaction and uneven chlorination in the later stages. By using a six-stage gradient temperature and pressure increase, the chlorination reaction maintains a suitable rate throughout the process, ensuring a uniform distribution of chlorine atoms on the polyvinyl chloride molecular chain. This guarantees that the chlorine content of the CPVC meets the standards, while also achieving excellent thermal stability and mechanical properties.

[0125] Step SA26 uses the criterion of stopping chlorination when the total chlorine flow reaches 105%~115% of the theoretical chlorine content. Combined with the boundary constraints of a maximum reactor pressure of 0.27 MPa and a maximum reactor temperature of 115°C, it achieves multi-dimensional and precise control of the chlorination endpoint. Compared to control methods that rely solely on reaction time or temperature and pressure changes, the multi-index endpoint judgment mechanism, with chlorine flow as the primary indicator and temperature and pressure as secondary indicators, more accurately reflects the actual progress of the chlorination reaction. This avoids low chlorine content due to insufficient chlorine flow or over-chlorination, discoloration, and decomposition of the product due to excessive chlorine flow, ensuring the consistency of CPVC product indicators for each batch.

[0126] After the chlorination reaction is completed, "immediately and rapidly reduce the temperature and pressure" to quickly terminate the chlorination reaction and avoid over-chlorination or thermal decomposition of CPVC at high temperatures. When the pressure in the reactor drops to 0.05 MPa, open the tail gas valve to discharge residual chlorine, and discharge the residual chlorine gas in the reactor into the secondary alkaline washing system 10 for treatment. After the residual chlorine is completely discharged, the reactor is ready to be safely opened, and the material can be safely discharged to the post-processing unit 6. At the same time, the reactor can quickly enter the production preparation state for the next batch, improving the equipment turnover efficiency.

[0127] In this embodiment, process step B includes:

[0128] SB1, Vent and remove oxygen, heat up the reactor; the suspension is transferred from the batching reactor 2 to the chlorination reactor 5, keep the tail gas venting and heating to remove oxygen, heat up to the initial reaction temperature of 70°C, close the tail gas valve, and start chlorination;

[0129] SB2 and CPE three-stage temperature and pressure controlled chlorination;

[0130] SB21, low-temperature initiation at a vessel temperature of 70~90℃, chlorination rate of 2~5 Kg / min, vessel pressure of 0.05~0.15 MPa;

[0131] SB22, main reaction at a reactor temperature of 95~110℃, chlorine flow rate of 3~7 Kg / min, reactor pressure of 0.15~0.25 MPa;

[0132] SB23, high-temperature homogenization and chlorine supplementation at a vessel temperature of 115~130℃, chlorine flow rate of 1~3 Kg / min, vessel pressure of 0.20~0.30MPa;

[0133] SB3, Endpoint Control: After the target chlorine content is reached, chlorine supply is stopped, the maximum pressure in the reactor is controlled at 0.30 MPa, the reactor temperature is ultimately controlled at 130℃, and then automatically cooled down to 70℃. Compressed air is used to pressurize the material to the shared post-processing unit 6.

[0134] In step SB1, the CPE production process adopts the method of "maintaining exhaust gas venting, heating and oxygen removal", which gradually removes the air (oxygen) from the system, which helps to maintain the original properties of the polyethylene raw material.

[0135] Step SB2 divides the CPE chlorination process into three stages: a low-temperature initiation stage (70~90℃), a main reaction stage (95~110℃), and a high-temperature homogenization and chlorination stage (115~130℃). Polyethylene chlorination exhibits a significant "self-accelerating" characteristic: once the chlorination reaction is initiated, chlorine atoms on the molecular chain promote further chlorination at adjacent sites. The low-temperature initiation stage safely starts the chlorination reaction at a moderate chlorination rate (2~5 kg / min) and a low reactor pressure (0.05~0.15 MPa); the main reaction stage increases the chlorination rate (3~7 kg / min) and reactor pressure (0.15~0.25 MPa) to allow the chlorination reaction to proceed at a higher rate; the high-temperature homogenization and chlorination stage raises the reactor temperature to 115~130℃ and uses a lower chlorination rate (1~3 kg / min) for deep chlorination and molecular chain homogenization, resulting in a more thermodynamically uniform distribution of chlorine atoms on the polyethylene molecular chain. This three-stage process effectively controls the chlorination rate of CPE throughout the entire process, avoiding the problems of over-chlorination in the early stage and reaction stagnation in the later stage.

[0136] Step SB3 uses "reaching the target chlorine content" as the basis for stopping chlorination. The maximum reactor pressure is controlled at 0.30 MPa and the maximum reactor temperature at 130°C. The material is then automatically cooled to 70°C and pressurized with compressed air to the post-processing unit 6. The maximum temperature control of 130°C is crucial for CPE: excessively high temperatures can cause cross-linking or degradation of the polyethylene molecular chains, severely affecting the toughness and processing performance of CPE. Cooling to 70°C reduces material flowability, facilitating transport, and simultaneously prevents high-temperature material from directly entering the post-processing equipment 603, which could cause equipment corrosion or pipeline blockage.

[0137] Example 1 (Preparation of chlorinated polyvinyl chloride)

[0138] 4000 kg of polyvinyl chloride resin was precisely metered and fed into a shared batching tank via a shared closed raw material conveying system; 16000 kg of [unspecified material] was then added to the batching tank. A 16% concentration of dilute hydrochloric acid (recycled from the hydrochloric acid recovery unit) is added to a shared additive dosing system with 0.3% benzoyl peroxide and silica sol dispersant. The mixture is stirred and emulsified for 0.5 hours to form a uniform suspension. The suspension is then transferred to a shared chlorination reactor, purged with nitrogen for 30 minutes, heated to 80°C, and chlorinated to remove nitrogen. The chlorination is carried out using a six-stage gradient temperature control, with a total chlorination amount of 110% of the theoretical amount. The mixture is then rapidly cooled and discharged. After passing through a shared post-treatment unit, the filter cake enters a transfer reactor where water is added in a set ratio to form a slurry. The slurry is pumped to mixing tank A in the drying workshop for uniform mixing, and then pumped into a shared centrifuge for centrifugation. The centrifuged cake is then sent to drying system A for drying. The dried chlorinated polyvinyl chloride product enters a dedicated finished product silo A. From the silo, the material is discharged into the receiving hopper of packaging machine A and then connected to the dedicated packaging machine A for packaging. The packaged bagged material enters a shared post-packaging line, where it undergoes metal detection, weighing on a re-inspection scale, coding, and palletizing to complete the final packaging process.

[0139] The product has a chlorine content of 67.12%, a thermal decomposition temperature of 126℃, an aging whiteness of 80% at 160℃ / 10min, and meets the standards for no lumps or impurities. The packaging is also qualified.

[0140] Example 2 (Preparation of chlorinated polyethylene)

[0141] No equipment modification is required; simply switch the DCS system to the chlorinated polyethylene production parameter mode. Through a shared closed-loop raw material conveying system, the corresponding amount of polyethylene powder is precisely metered and fed into a shared batching tank. Water (suspension) is added to the batching tank, and a composite initiator is added through a shared additive dosing system. The mixture is stirred and emulsified for 0.5 hours to form a uniform suspension. The suspension is then transferred to the same chlorination reactor, where chlorination begins at 70°C and is controlled in three stages. After chlorination, the mixture is cooled to 70°C and pressed into a shared post-treatment unit. The material is then filtered... The cake enters the transfer kettle and is mixed with water according to the set ratio to form a slurry. The slurry is then pumped to the mixing tank B in the drying workshop for uniform mixing. It is then pumped into a shared centrifuge for centrifugation. The centrifuged cake is then sent to the drying system B for drying. The dried chlorinated polyethylene product enters the dedicated finished product silo B. It is then discharged from the silo to the mixer, where a release agent is added and mixed evenly. The mixture is then conveyed to the receiving hopper of the packaging machine B and connected to the dedicated packaging machine B for packaging. The packaged bagged material enters the shared post-packaging line and sequentially undergoes metal detection, re-inspection weighing, coding, and palletizing to complete the final packaging process.

[0142] The reaction cycle is 6-7 hours, the residual chlorine in the tail gas is less than 0.3%, the wastewater meets the discharge standards, the finished product is free of lumps, the particles are uniform, and the packaging is qualified.

[0143] Using the suspension-based co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene provided in this embodiment to produce chlorinated polyvinyl chloride and chlorinated polyethylene by suspension method has the following beneficial effects:

[0144] 1. Reduce equipment investment and operating costs, and improve production efficiency.

[0145] In existing technologies, chlorinated polyvinyl chloride (PVC) and chlorinated polyethylene (PE) each require independent production lines, resulting in significant duplication of equipment investment. This invention combines shared and dedicated equipment, including a batching tank, chlorination reactor, post-processing core equipment, hydrochloric acid recovery unit, secondary alkaline washing system, and DCS control system. Dedicated units are set up for raw material supply, slurry mixing, drying, and finished product packaging. Compared to two independent production lines, this reduces equipment investment, floor space requirements, energy consumption, and improves production economics. Simultaneously, the utilization rate of shared equipment is significantly increased, avoiding resource waste caused by equipment idleness during periods of downtime in single-product production.

[0146] 2. Enable rapid and flexible product switching

[0147] Currently, switching between two independent production lines requires replacing the entire set of equipment, while directly merging the two sets of equipment presents problems such as cumbersome parameter adjustments and susceptibility to errors. This invention addresses this by using a DCS control system to preset two complete process parameter packages for chlorinated polyvinyl chloride (process step A) and chlorinated polyethylene (process step B). Operators only need to call the corresponding mode to achieve one-click switching. The system automatically completes raw material selection, auxiliary agent ratio adjustment, chlorination temperature and pressure parameter conversion, post-processing path switching, and packaging method change, eliminating the need for manual adjustments and shortening the switching time. The DCS control system achieves fully automated control of raw material metering, auxiliary agent addition, temperature and pressure control, tail gas treatment, hydrochloric acid recovery, and finished product packaging, avoiding the risk of reaction runaway due to human error and improving the safety and reliability of the production process.

[0148] 3. Avoid cross-contamination between products and ensure stable quality of both products.

[0149] Directly merging the two sets of equipment can easily lead to cross-contamination of the products. This invention addresses this technical challenge by implementing dual safeguards at key distribution points while sharing core equipment: independent raw material silos A (for PVC) and B (for PE) are located at the raw material end; two independent dedicated mixing tanks (Mixing Tank A and Mixing Tank B) and two independent dedicated drying systems (Drying System A and Drying System B) are located at the post-processing end; and two independent finished product silos and a dedicated packaging machine are located at the finished product end. The CPE branch also includes a dedicated mixer for adding the release agent. This separation design of "dual raw material silos + dual mixing tanks + dual drying systems + dual finished product silos + dual packaging machines" prevents cross-contamination between the two products, ensuring the stable quality of both chlorinated polyvinyl chloride and chlorinated polyethylene.

[0150] 4. Achieve recycling of by-product hydrochloric acid

[0151] The byproduct acid from two independent systems cannot be recycled and reused in a coordinated manner, resulting in poor environmental and economic benefits. This invention enables closed-loop recycling of byproduct hydrochloric acid: the byproduct hydrochloric acid from the chlorination reactor and post-treatment unit is purified and impurities removed by a sedimentation filtration device and then stored in a hydrochloric acid storage tank, where it can be directly reused to prepare suspensions; alternatively, a falling film absorber (to concentrate dilute hydrochloric acid into high-concentration commercial hydrochloric acid for sale) or a deep-drainage system (to recover hydrogen chloride gas for reuse in the chlorination reaction, with residual acid recycled) can be selected as needed. This achieves zero waste acid discharge, solving the environmental problem of waste acid disposal and creating considerable economic benefits.

[0152] 5. Exhaust emissions meet standards

[0153] The chlorine-containing tail gas generated from the chlorination reaction of the two products is uniformly fed into a shared two-stage alkaline scrubbing system (first-stage alkaline scrubbing tower + second-stage alkaline scrubbing tower). After the residual chlorine is fully absorbed by the two-stage alkaline scrubbing, it meets the emission standards and there is no need to set up separate tail gas treatment equipment for the two products.

[0154] 6. Differentiated packaging balances product characteristics and packaging efficiency.

[0155] Chlorinated polyethylene (CPVC) is prone to clumping and requires the addition of a release agent before packaging, while chlorinated polyvinyl chloride (CPVC) does not have this requirement. This invention addresses this difference by using two dedicated packaging machines. CPVC enters packaging machine A directly from finished product silo A, while CPE enters a mixing machine from finished product silo B, where a release agent is added before entering packaging machine B. The discharge ends of both packaging machines converge on the same post-packaging line, sequentially completing standardized processes such as metal detection, re-inspection and weighing, coding, and palletizing. This design not only adapts to the packaging characteristics of the two products but also maximizes the sharing of post-packaging conveyor and palletizing equipment, balancing product storage stability and packaging efficiency.

[0156] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using a suspension process, characterized in that, This includes shared equipment and dedicated equipment; The shared equipment includes a closed raw material conveying system (1), a batching tank (2), a suspension dosing system (3), an auxiliary agent dosing system (4), a chlorination reactor (5), a post-processing unit (6), a centrifuge (7), a post-packaging line (8), a hydrochloric acid recovery unit (9), a secondary alkaline washing system (10), a chlorine supply unit (11), and a DCS control system (12). The special equipment includes raw material silo A (13), raw material silo B (14), nitrogen supply unit (15), mixing tank A (16), mixing tank B (17), drying system A (18), drying system B (19), finished product silo A (20), finished product silo B (21), packaging machine A (22), mixing machine (23), and packaging machine B (24); The raw material silos A (13) and B (14) are respectively connected to the closed raw material conveying system (1). The closed raw material conveying system (1), batching tank (2), chlorination reactor (5), and post-processing unit (6) are connected in sequence. The suspension addition system (3) and auxiliary agent addition system (4) are respectively connected to the batching tank (2). The chlorine supply unit (11) is connected to the chlorination reactor (5). The nitrogen supply unit (15) is connected to the chlorination reactor (5). The post-processing unit (6) is connected to the mixing tank A (16) and mixing tank B (17). The mixing tank A (16) and mixing tank B (17) are respectively connected to the centrifuge (7). The centrifuge (7) is respectively connected to the drying system A (18) and drying system B (17). System B (19), the drying system A (18), finished product silo A (20), and packaging machine A (22) are connected in sequence. The drying system B (19), finished product silo B (21), mixer (23), and packaging machine B (24) are connected in sequence. The packaging machine A (22) and packaging machine B (24) are connected to the post-packaging line (8) in sequence. The hydrochloric acid recovery unit (9) is connected to the post-processing unit (6) and centrifuge equipment (7) in sequence. The secondary alkaline washing system (10) is connected to the batching tank (2), chlorination reactor (5), and post-processing unit (6) in sequence. The DCS control system (12) is electrically connected to the common equipment and special equipment in sequence. The DCS control system (12) is used to store process step A for the suspension method of producing chlorinated polyvinyl chloride. Process step B for the suspension production of chlorinated polyethylene; according to the product selection instruction, the corresponding process step A or process step B is invoked, and the shared equipment and special equipment are controlled to work together to produce chlorinated polyvinyl chloride or chlorinated polyethylene by suspension.

2. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 1, characterized in that, The closed raw material conveying system (1) includes a ton bag breaking machine (101), an air conveying pipe (102), and a metering auger (103). The outlet of the ton bag breaking machine (101) is connected to the inlet of the air conveying pipe (102). The air conveying pipe (102) is connected to the inlets of the raw material silos A (13) and B (14) through branches, and valves are respectively installed on the branch pipes. The outlets of the raw material silos A (13) and B (14) are respectively connected to the inlet of the metering auger (103). The outlet of the metering auger (103) is connected to the inlet of the batching vessel (2).

3. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 1, characterized in that, The additive dosing system (4) includes an initiator preparation vessel (401), a metering tank A (402), a metering pump A (403), a mass flow meter A (404), a dispersant preparation vessel (405), a metering tank B (406), a metering pump B (407), and a mass flow meter B (408). The initiator preparation vessel (401), metering tank A (402), and metering pump A (403) are connected in sequence. The dispersant preparation vessel (405), metering tank B (406), and metering pump B (407) are connected in sequence. The metering pump A (403) and metering pump B (407) are respectively connected to the batching vessel (2) through pipelines. A mass flow meter A (404) and a valve are respectively installed on the connecting pipeline between metering pump A (403) and batching vessel (2). A mass flow meter B (408) and a valve are respectively installed on the connecting pipeline between metering pump B (407) and batching vessel (2).

4. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 1, characterized in that, The post-processing unit (6) includes a concentrated acid filter (601), a soaking tank (602), a post-processing device (603), a transfer tank (604), and a slurry pump (605) connected in sequence. The inlet of the concentrated acid filter (601) is connected to the outlet of the chlorination reactor (5). The outlet of the slurry pump (605) is connected to the inlets of the mixing tank A (16) and the mixing tank B (17), respectively. Valves are respectively installed on the connecting pipes of the slurry pump (605) and the mixing tank A (16) and the mixing tank B (17). The transfer tank (604) is equipped with a slurry mixing device (606).

5. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 4, characterized in that, The hydrochloric acid recovery unit (9) includes a sedimentation filtration device (901) and a hydrochloric acid storage tank (902). The hydrochloric acid outlets of the concentrated acid filter (601) and the centrifuge (7) are respectively connected to the inlet of the sedimentation filtration device (901). The outlet of the sedimentation filtration device (901) is connected to the inlet of the hydrochloric acid storage tank (902). The outlet of the hydrochloric acid storage tank (902) is connected to the inlet of the suspension dosing system (3).

6. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 5, characterized in that, The hydrochloric acid recovery unit (9) further includes a falling film absorber (903) and / or a deep desorption system (904); The hydrochloric acid storage tank (902) is a zoned mixing storage tank, including a concentrated acid storage tank (905) and a dilute acid storage tank (906). The hydrochloric acid outlets of the concentrated acid filter (601) and the centrifuge (7) are respectively connected to the concentrated acid storage tank (905). The inlets of the falling film absorber (903) and / or the deep anaerobic digester (904) are connected to the outlets of the concentrated acid storage tank (905), and the dilute acid outlets of the falling film absorber (903) and / or the deep anaerobic digester (904) are connected to the inlets of the dilute acid storage tank (906).

7. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 1, characterized in that, The secondary alkaline washing system (10) includes a primary alkaline washing tower (1001) and a secondary alkaline washing tower (1002). The gas inlet of the primary alkaline washing tower (1001) is connected to the exhaust gas outlet of the batching vessel (2), the chlorination reactor (5), and the post-treatment unit (6). The exhaust gas outlet of the primary alkaline washing tower (1001) is connected to the gas inlet of the secondary alkaline washing tower (1002).

8. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 1, characterized in that, The process step A includes: SA1, nitrogen purging to remove oxygen, heating in the reactor; after the suspension is transferred from the batching reactor (2) to the chlorination reactor (5), nitrogen is used to purge oxygen for more than 25 minutes, the system automatically heats up to 70~80℃, and stirring is started; SA2, CPVC six-stage gradient chlorination; SA21, chlorine is introduced to remove nitrogen. The chlorine rate is 2-4 kg / min. Chlorine is introduced for 6-8 minutes to remove nitrogen. Then, the tail gas valve is closed. SA22, control the chlorination rate at 3~5 Kg / min, the pressure at the reactor at 0.05~0.1 MPa, and the reactor temperature at 90~95℃; SA23, control the chlorination rate at 4~9 Kg / min, the pressure at the vessel at 0.1~0.13MPa, and the temperature at the vessel at 95~99℃; SA24, control the chlorination rate at 4~7 Kg / min, the pressure at the reactor at 0.13~0.18 MPa, and the temperature at the reactor at 99~101℃; SA25, control the chlorination rate at 2~6 Kg / min, the pressure at the reactor at 0.18~0.23 MPa, and the temperature at the reactor at 101~105℃; SA26. When the total chlorine flow reaches 105%~115% of the theoretical chlorine consumption, stop the chlorine flow. At this time, the maximum pressure of the reactor is controlled at 0.27 MPa, and the reactor temperature is finally controlled at 115℃. Then, immediately force rapid cooling and pressure reduction. When the reactor pressure drops to 0.05 MPa, open the tail gas valve to discharge the residual chlorine, and discharge the material into the common post-treatment unit (6).

9. The co-line production system for chlorinated polyvinyl chloride and chlorinated polyethylene using suspension polymerization as described in claim 1, characterized in that, The process step B includes: SB1, Vent and remove oxygen, heat up inside the reactor; the suspension is transferred from the batching reactor (2) to the chlorination reactor (5), keep the tail gas venting and heating to remove oxygen, heat up to the initial reaction temperature of 70℃, close the tail gas valve, and start chlorination; SB2 and CPE three-stage temperature and pressure controlled chlorination; SB21, low-temperature initiation at a vessel temperature of 70~90℃, chlorination rate of 2~5 Kg / min, vessel pressure of 0.05~0.15 MPa; SB22, main reaction at a reactor temperature of 95~110℃, chlorine flow rate of 3~7 Kg / min, reactor pressure of 0.15~0.25 MPa; SB23, high-temperature homogenization and chlorination at a vessel temperature of 115~130℃, chlorination rate of 1~3 Kg / min, vessel pressure of 0.20~0.30 MPa; SB3, Endpoint control: After the target chlorine content is reached, chlorine supply is stopped, the maximum pressure of the reactor is controlled at 0.30 MPa, the final temperature of the reactor is controlled at 130℃, and then it is automatically cooled down to 70℃. Compressed air is used to pressurize the material to the common post-processing unit (6).

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