Solid-phase tackifying, cooling and humidifying system and process for nylon slices

Abstract

The invention discloses a solid-phase tackifying, cooling and humidifying system and a solid-phase tackifying, cooling and humidifying process for nylon. The cooling and humidifying of a slice are realized while a high-viscosity nylon slice is produced; on the basis of the prior art, a cooling function and a humidifying function are innovatively combined, and remarkable technical progress is achieved. According to the system, an interlocking control system of a cooling circulation nitrogen flow meter, a regulating valve and a temperature and dew point detector is additionally arranged on a cooling unit, so that dynamic regulation of the gas-solid ratio (0.05-0.5) of supplied gas and graded dew point control are realized, and the water content control precision is improved to + / -50ppm from + / -100ppm of a traditional process. By optimizing the nitrogen circulation path and the retention time (1.5-6 hours), a single set of system can be compatible with production modes with different water content requirements of 400-1000 ppm, the investment is saved by 40% and the energy consumption is reduced by 20% compared with a mode of additionally arranging humidifying equipment, the remarkable technical advantages are shown, and the industrial application prospect is good.

Description

Technical Field

[0001] The invention belongs to the technical field of nylon production, and in particular relates to a solid-phase viscosity-increasing and cooling and humidifying system and process for nylon chips. Background Art

[0002] In the field of special engineering plastics and chemical fibers, the solid-phase viscosity-increasing process of nylon chips is a key link in improving the performance of materials. At the same time, the moisture content of nylon chips after solid-phase viscosity-increasing often cannot meet the process requirements of spinning, and often requires the addition of a humidifying device for humidity adjustment, which increases investment and operating costs. For example, a humidity adjustment system for nylon production disclosed in CN201621289106.9 is to adjust the humidity in the form of a humidity adjustment tower added after the drying tower. The process control process is relatively complex and energy consumption is high. CN202411976398.2 discloses a solid-phase viscosity-increasing system and process suitable for high-strength polyamide chip spinning. It also adds a humidity adjustment system after the dry chip silo after solid-phase viscosity-increasing, and has the same disadvantages.

[0003] There is an urgent need for a nylon chip solid phase viscosity increasing cooling and humidification system and process that does not require additional humidity control equipment and has relatively simple process control to achieve a chip moisture content that meets process requirements. Summary of the Invention

[0004] In order to effectively solve the many problems existing in the background technology, the present invention discloses a solid phase viscosity increasing and cooling and humidifying system and process for nylon chips. The system has three process methods that can solve the existing problems:

[0005] The integrated structure described in the present invention refers to a physical connection between the solid-phase viscosity increasing reactor and the cooling unit through an integrated device. The two share the same shell structure and are directly connected internally. In the embodiment, the cooling unit is named "cooling section". Its specific structure can refer to the integrated solid-phase viscosity increasing device described in Examples 1-2 of patent CN202122949552.5, wherein the reaction section and the cooling section realize self-flowing transportation of slices through a built-in conical transition structure, and the nitrogen circulation system shares the same pipeline;

[0006] The split structure means that the solid phase viscosity increasing reactor and the cooling unit are separately arranged as independent equipment, and the two are connected by a connecting component (rotary feeding valve or straight pipe) to realize the transmission of slices and nitrogen. In the embodiment, the cooling unit is named "cooling silo", and its volume is designed to be 0.1 to 0.2 times that of the reactor to meet the residence time requirement of 1.5 to 6 hours. The nitrogen circulation of the split structure needs to return to the reactor through an independent pipeline via a nitrogen heater, which is different from the internal circulation path of the integrated structure.

[0007] The "integrated structure" in claim 1 corresponds to the above-mentioned integrated cooling section, and its technical essence lies in eliminating the intermediate conveying equipment between the reactor and the cooling unit, and realizing continuous processing of slices through the built-in flow channel; the "split structure" corresponds to the independently set cooling silo, and its technical essence lies in solving the material transportation between the split equipment through a rotary feeding valve or a straight pipe.

[0008] The naming differences of the two structures (cooling section / cooling silo) are unified in Examples 1-3 of the specification, and the cooling unit components (cooling fan, nitrogen cooler, etc.) described in Claims 2-4 are configured with the same connection relationship in the two structures, and only the installation position has spatial differences due to the integrated / split design.

[0009] Specifically, the nylon solid phase viscosity increasing and cooling and humidifying system of the present invention comprises:

[0010] Solid phase viscosity increasing reaction unit, used for viscosity increasing treatment of nylon chips;

[0011] A cooling unit is used to cool and humidify the nylon chips after viscosity increase;

[0012] A circulating nitrogen control system is used to cooperate with the cooling unit to cool and humidify the nylon chips after viscosity increase, comprising:

[0013] A gas circulation loop connecting the air outlet and the air inlet of the cooling unit;

[0014] A cooling fan is provided on the gas circulation loop;

[0015] A nitrogen cooler is connected to the outlet side of the cooling fan;

[0016] A gas supply pipeline connects the gas circulation loop with an external nitrogen source for supplying nitrogen;

[0017] Dew point detector, installed in the gas circulation loop to monitor gas humidity;

[0018] A temperature control element is provided at the outlet of the nitrogen cooler for regulating the gas temperature;

[0019] The solid-phase viscosity-increasing reaction unit and the cooling unit are of an integrated structure or a split structure, and the split structure is connected via a rotary feeding valve or a straight-through pipe to achieve material transmission between the solid-phase viscosity-increasing reaction unit and the cooling unit.

[0020] For the technical solution described above, it is further preferred that

[0021] The gas circulation loop:

[0022] The cooling unit has an air outlet connected to the inlet of the cooling fan through a pipe;

[0023] The cooling fan has its outlet connected to the inlet of the nitrogen cooler through a pipeline;

[0024] The nitrogen cooler has its outlet connected to the air inlet of the cooling unit through a pipeline;

[0025] The air supply pipeline:

[0026] The air supply pipeline is connected to the front section of the cooling fan inlet;

[0027] A regulating valve and a flow meter are sequentially arranged on the air supply pipeline to adjust the flow of the supplementary nitrogen.

[0028] For the technical solution described above, it is further preferred that

[0029] The outlet pipe of the nitrogen cooler is provided with a dew point detector and a temperature control element;

[0030] A cooling water regulating valve is provided on the cooling water inlet pipe of the nitrogen cooler.

[0031] For the technical solution described above, it is further preferred that, in the split structure, the nitrogen discharged from the air outlet of the cooling unit needs to be heated to 150-180° C. by a nitrogen heater and then returned to the solid phase viscosity increasing reaction unit.

[0032] For the technical solution described above, it is further preferred that

[0033] The dew point detector is interlocked with the regulating valve to form a dynamic feedback control system, and the interlock control response time is ≤ 10 seconds to control the humidity of the circulating nitrogen;

[0034] The temperature control element is interlocked with the cooling water regulating valve to form a dynamic feedback control system for controlling the temperature of the circulating nitrogen;

[0035] The cooling fan is a variable frequency controlled fan, and its motor is connected to a variable frequency controller; the gas-to-solid ratio of the cooling cycle nitrogen flow and the slice flow is maintained through variable frequency control.

[0036] Another aspect of the present invention provides a solid phase viscosity increasing and cooling and humidifying process for nylon chips of the system described above, which comprises the following steps:

[0037] (1) Nylon chips with a relative viscosity of 2.4 to 2.7 are subjected to solid phase viscosity enhancement and then enter the cooling unit, where the chip temperature is reduced from the reaction temperature of 140 to 170°C to the same cooling inlet temperature;

[0038] (2) Fresh high dew point nitrogen with a dew point of 10-30°C is drawn from the solid phase thickening nitrogen treatment system, measured by a flow meter, and controlled by a regulating valve to be fed into the cooling unit. The dynamic adjustment range of the gas-to-solid ratio is 0.05-0.5;

[0039] (3) The humidity of the circulating nitrogen is monitored in real time by a dew point detector. When the detection value deviates from the set threshold of -20 to 20°C, the interlocking regulating valve adjusts the air supply flow within 10 seconds or less to ensure that the humidity of the cooling circulating nitrogen is within the set threshold and maintain the moisture content of the slices at the outlet of the cooling unit within the set range;

[0040] (4) Control the ratio of cooling cycle nitrogen flow to slice flow (gas-to-solid ratio) to 2.0-4.0;

[0041] (5) Control the slices’ residence time in the cooling unit to be 1.5 to 6 hours.

[0042] (6) The cooling water flow rate is adjusted by the cooling water regulating valve to control the temperature of the cooling circulating nitrogen entering the cooling unit to 35~55℃.

[0043] For the technical solution described above, it is further preferred that the final moisture content of the finished slices is controlled within the range of 400 to 1000 ppm by quantitatively supplementing high dew point nitrogen and adjusting the gas-solid ratio of cooling and humidification and adopting PID control mode.

[0044] For the technical solution described above, it is further preferred that when producing slices with a moisture content of 500±50ppm, the air-to-solid ratio is set to 0.05~0.1, the threshold of the dew point detector is set to -15~-5℃, the temperature of nitrogen entering the cooling unit is 40℃, and the ratio of the cooling cycle nitrogen flow to the slice flow is 2.0~3.0.

[0045] For the technical solution described above, it is further preferred that when producing slices with a water content requirement of 500±50ppm, the control parameters include:

[0046] (1) Dew point detector setting value: -10±0.5℃;

[0047] (2) Ratio of cooling cycle nitrogen flow to slicing flow: 2.5 ± 0.2;

[0048] (3) Temperature of circulating nitrogen entering the cooling unit: 40±1℃;

[0049] (4) Moisture content of finished slices: 500±50ppm, CV value ≤1.5%.

[0050] For the technical solution described above, it is further preferred that when producing slices with a moisture content of 800±50ppm, the gas-to-solid ratio of the air supply is increased to 0.1~0.2, the threshold of the dew point detector is raised to -10~0℃, the temperature of the nitrogen entering the cooling unit is 40℃, and the ratio of the cooling cycle nitrogen flow to the slice flow is 2.0~3.0.

[0051] For the technical solution described above, it is further preferred that the ratio of the cooling cycle nitrogen flow rate to the slice flow rate is 3.0, and the residence time is 5 hours.

[0052] The cooling unit of the present invention realizes the cooling and humidification function. Specifically, the reaction section and the cooling and humidification section can be integrated into one design, or the reactor and the cooling silo can be separated into a design. By quantitatively supplementing fresh high dew point nitrogen (dew point 10-30°C) from the solid-phase viscosity-increasing nitrogen treatment system, the flow rate, temperature and dew point of the circulating nitrogen in the cooling unit can be accurately adjusted. After the supplemented high dew point nitrogen is heated by the slices coming out of the reaction unit, it enters the reaction unit through the inlet and is mixed with the fresh high dew point nitrogen at the bottom of the reaction unit (the gas-solid ratio after mixing is 1.5-3.0) for solid-phase viscosity-increasing reaction. In order to ensure that the outlet temperature and water content of the cooling unit are relatively stable, the cooling unit needs to have sufficient gas flow and residence time. Usually, the gas-solid ratio of the cooling and humidifying air volume of the cooling unit is (2-4), and the residence time is designed to be 1.5-6 hours to ensure that the outlet temperature of the slice is consistent with the cooling inlet temperature and the water content is stable in an adjustable range of 400-1000ppm.

[0053] The dynamic control mechanism described in this invention uses a dew point detector to monitor the humidity of the circulating nitrogen in real time. When the measured value falls below a set threshold, an interlocking control valve adjusts the replenishment flow rate within 10 seconds or less (the gas-to-solid ratio of fresh high-dew-point nitrogen replenishment to the slice flow rate is 0.05-0.5. The replenishment flow rate varies based on the product's moisture content requirements, increasing the flow rate when the moisture content is high and decreasing it when the moisture content is low). This closed-loop control system keeps moisture content fluctuations within ±50 ppm. Simultaneously, through interlocking control of the temperature control element and the cooling water control valve, nitrogen temperature fluctuations are maintained within a ±1°C range.

[0054] The technical solution of the present invention is described in detail below:

[0055] 1. Integrated structural system

[0056] The present invention is an improvement on the integrated two-component nylon solid-phase viscosity increasing reactor and its supporting nitrogen circulation system involved in the utility model patent CN202122949552.5. In the cooling unit, the system is specially provided with the following components to realize the efficient and precise control of the moisture content of the final nylon slices by cooling and humidification during the solid-phase viscosity increasing process.

[0057] Specific technical solutions include:

[0058] System hardware configuration

[0059] Main gas circulation path: The gas outlet of the cooling unit is connected to the inlet of the cooling fan, the outlet of the cooling fan is connected to the inlet of the nitrogen cooler, and the outlet of the nitrogen cooler returns to the gas inlet of the cooling unit through a pipeline, forming a closed loop circulation;

[0060] A water flow regulating valve is installed on the cooling medium inlet pipe of the nitrogen cooler, and a high-precision temperature sensing element is installed on the outlet pipe;

[0061] Air supply system: The outlet of the nitrogen treatment system is connected to the front section of the cooling fan inlet through an independent pipeline, and a gas flow metering device and an electric regulating valve are installed on the air supply pipeline in sequence.

[0062] Intelligent control system

[0063] Humidity control: A dew point detection device is installed at the outlet pipe of the nitrogen cooler to monitor the humidity of the circulating gas in real time and form an interlocking control with the air supply control valve. When the detection value exceeds the set threshold range (-20℃ to 20℃), the system automatically adjusts the opening of the air supply valve within 10 seconds;

[0064] Temperature control: Through real-time feedback data from temperature sensing elements, the cooling medium flow rate is dynamically adjusted to maintain the circulating gas temperature within the precise range of 35°C to 55°C;

[0065] Flow control: Through real-time feedback data from flow sensor elements, the cooling fan inverter frequency is dynamically adjusted to maintain a stable circulating gas flow.

[0066] Double closed loop: The cooling cycle nitrogen flow, humidity and temperature control systems operate independently and work together to ensure that the slice moisture content is controlled with an accuracy of ±50ppm.

[0067] Process advantages

[0068] The integrated design eliminates the need for independent humidity control equipment, reducing system energy consumption by more than 20%;

[0069] By adjusting the air supply volume (gas-solid ratio 0.05-0.5) and the circulating gas flow rate (gas-solid ratio 2.0-4.0), a wide range of moisture content control of 400-1000ppm can be achieved;

[0070] The slices stay in the cooling unit for 1.5-6 hours to ensure uniformity of temperature and humidity.

[0071] 2. Split structure system

[0072] A split solid phase viscosity increasing reactor is connected to the cooling silo through a rotary feeding valve, and the purpose of cooling and humidification is achieved through process control: For working conditions that require a split setting, the present invention provides another embodiment:

[0073] Device connection solution

[0074] The solid phase viscosity increasing reactor and the cooling silo are placed separately as independent equipment;

[0075] The two devices are connected by a mechanical rotary feeding valve or a straight-through conveying pipeline to ensure the airtightness of material transmission;

[0076] The cooling silo volume is designed to be 0.1-0.2 times that of the reactor to meet the process residence time requirements.

[0077] Key points of process control

[0078] (1) Material processing: After the nylon chips with a relative viscosity of 2.4-2.7 are subjected to a viscosity-increasing reaction at 140-170°C, they are transported to a cooling silo;

[0079] (2) Gas control: fresh nitrogen with a dew point of 10-30°C is introduced from the nitrogen treatment system, and the gas supply volume is controlled by flow metering and valve adjustment (gas-to-solid ratio 0.05-0.5);

[0080] (3) Real-time monitoring: A dew point detection device is used to monitor the humidity of the circulating gas. When the value deviates from the set range, the interlock system adjusts the gas replenishment parameters within 10 seconds;

[0081] (4) Process parameters: maintain the circulating gas to slice flow ratio at 2.0-4.0 and control the residence time at 1.5-6 hours;

[0082] (5) Temperature management: By adjusting the cooling medium flow rate, the circulating gas inlet temperature is precisely controlled within the range of 35-55°C. The temperature control element monitors the nitrogen temperature in real time and is interlocked with the cooling water regulating valve to form a closed-loop control.

[0083] The regulating valve and the cooling water regulating valve both adopt PID control mode, and form a closed-loop control system with the dew point detector and the temperature control element respectively. The PID control mode is conventional technology in this field and will not be described in detail in this patent.

[0084] Control Mode

[0085] Adopt multi-parameter linkage control system to synchronously adjust key parameters such as temperature, humidity, gas-solid ratio, etc.

[0086] For civil spinning-grade chips (moisture content 500±50ppm), the dew point detection threshold is set to -10±0.5℃ and the gas temperature is 40±1℃;

[0087] System stability index: moisture content fluctuation ± 50ppm, temperature fluctuation ± 1℃, viscosity fluctuation ± 0.02.

[0088] Compared with the prior art, the beneficial effects of the present application are:

[0089] The present application realizes significant technical progress through the integration of cooling and humidification functions. Without additional humidification tower, through the technical scheme of dynamically adjusting the gas-solid ratio of the air supply and controlling the hierarchical dew point and temperature closed-loop regulation, the present application significantly improves the moisture control accuracy and improves the temperature uniformity. Compared with the traditional process, the present application not only prolongs the residence time of the material, but also realizes energy saving. A single system can be compatible with multiple production modes with different moisture content requirements. This integrated design not only improves the process control accuracy, but also significantly reduces equipment investment and maintenance costs, showing obvious technical advantages. BRIEF DESCRIPTION OF DRAWINGS

[0090] Figure 1 : The solid-phase tackifying and cooling and humidifying system and process schematic diagram of nylon described in the present application - reaction section and cooling section (cooling unit) integrated solid-phase tackifying working condition;

[0091] Figure 2 : The solid-phase tackifying and cooling and humidifying system and process schematic diagram of nylon described in the present application - solid-phase tackifying and cooling bin connected through rotary feeding valve working condition;

[0092] Figure 3 : The solid-phase tackifying and cooling and humidifying system and process schematic diagram of nylon described in the present application - solid-phase tackifying and cooling bin connected through straight pipe working condition;

[0093] Wherein: 01. Cooling fan, 02. Nitrogen cooler, 03. Cooling water regulating valve, 04. Temperature control element, 05. Dew point detector of cooling inlet air, 06. Regulating valve, 07. High dew point nitrogen flowmeter, 08. Nitrogen heater, 09. Reaction section (reactor nitrogen outlet is arranged at the top), 10. Reaction section (reactor nitrogen inlet is arranged at the bottom side wall), 11. Cooling section (cooling unit, cooling bin nitrogen outlet is arranged at the upper side wall), 12. Cooling section (cooling unit, cooling bin nitrogen inlet is arranged at the lower side wall), 13. Rotary feeding valve. DETAILED DESCRIPTION

[0094] In the detailed description section, the following non-limiting examples can make those skilled in the art more fully understand the present application, but do not limit the present application in any way. The specific structural units, connection relationship and cooperation relationship of the system and process will be described in detail in the detailed description, including but not limited to the detailed connection mode and working principle of the key components.

[0095] The gas-solid ratio in the example is the volume flow (Nm3 / h) to the slice mass flow rate (kg / h);

[0096] System structure description:

[0097] The system of the present invention includes a solid phase viscosity increasing reaction unit (hereinafter referred to as a specific reaction section or reactor in the embodiments) and a cooling unit (hereinafter referred to as a specific cooling section or cooling bin in the embodiments), both of which can adopt an integrated or split structural design. The details are as follows:

[0098] Integrated structure ( Figure 1 ):

[0099] The solid phase viscosity increasing reaction unit and the cooling unit are designed as an integrated whole, and the whole is called an "integrated solid phase viscosity increasing reactor".

[0100] Among them, the reaction part is named the reaction section, and the cooling part is named the cooling section (because the two are integrated in the same equipment, the cooling section and the reaction section of the integrated reactor are connected through an internal conical structure, so that the thickened slices naturally fall into the cooling section under the action of gravity).

[0101] For an embodiment of this structure, reference may be made to the integrated device disclosed in patent CN202122949552.5.

[0102] Split structure ( Figure 2 、 Figure 3 ):

[0103] The solid phase viscosity increasing reaction unit and the cooling unit are separately arranged and are respectively called a reactor and a cooling silo.

[0104] The two are connected through a rotary feeding valve or a straight pipe to achieve material transmission.

[0105] Technical feature relevance:

[0106] Reaction section: only used for integrated structures, refers to the part of the integrated reactor where the solid-phase viscosity-increasing reaction occurs.

[0107] Reactor: Only used for split structure, refers to independent solid phase viscosity increasing reaction equipment.

[0108] Cooling section: The cooling part integrated with the reaction section in the integrated structure.

[0109] Cooling silo: independent cooling equipment in split structure.

[0110] The integrated cooling section and reaction section share the same nitrogen circulation system, and the cooling and humidification process is completed directly inside the equipment.

[0111] In the split structure, the reactor and the cooling bin are connected by connecting components (such as rotary feeding valve) to realize the coordinated control of materials and nitrogen, and to ensure the connection of cooling and humidifying functions.

[0112] Example 1: Solid-phase tackifying cooling and humidifying system for nylon chips

[0113] Solid-phase tackifying and cooling and humidifying system for nylon chips,

[0114] An adjusting valve 06 and a flow meter 07 are arranged between the outlet of the nitrogen treatment system and the inlet pipeline of the cooling fan 01.

[0115] The cooling section air outlet 11 is connected with the cooling fan 01, the nitrogen cooler 02 and the dew point detector 05 at the outlet of the nitrogen cooler 02 in sequence, and finally returns to the solid-phase tackifying reactor of the integrated bicomponent nylon through the cooling section air inlet 12. The cooling water adjusting valve 03 is installed on the cooling water inlet pipeline of the nitrogen cooler 02, and the temperature control element 04 is arranged on the outlet pipeline, forming a nitrogen temperature closed-loop control system.

[0116] The adjusting valve 06 and the dew point detector 05 are interlocked to form a dynamic feedback control system, and the air supplementing flow response time is ≤10 seconds.

[0117] The low-viscosity nylon chips (relative viscosity 2.5) are fed into the reactor through the feeding port, and after the solid-phase tackifying in the reaction section, the chips with the temperature reduced to below 170℃ enter the cooling section, and in the cooling section, the cooling and humidifying process is realized, as follows:

[0118] In the reaction section, the chips continue to perform the polycondensation reaction under the action of fresh nitrogen at the bottom, and the molecular weight and viscosity are increased accordingly. The tackified chips directly fall into the cooling section at the bottom of the integrated nylon solid-phase tackifying reactor. In the cooling section, the tackified chips after the solid-phase tackifying are humidified to about 500ppm by supplementing a certain amount of high-dew-point nitrogen into the cooling circulating nitrogen, and at the same time, the chips are cooled to 40±1℃ by the circulating cold nitrogen. The residence time is controlled to be 4 hours to ensure that the chips are fully humidified and the temperature is homogenized in the cooling and humidifying section of the cooling section.

[0119] Cooling and humidifying control: the fresh high-dew-point nitrogen (dew point 20℃) introduced from the solid-phase tackifying nitrogen treatment system is metered by the flow meter, and is supplemented into the cooling section through the adjusting valve. According to the target of 500ppm of moisture content, the air-solid ratio of the air supplementing is set to be 0.1 (the dynamic adjusting range of the air-solid ratio of the air supplementing is 0.05-0.5);

[0120] Dynamic adjustment: the dew point detector 05 monitors the humidity of the circulating nitrogen in real time, and when the detected value is lower than -15℃, the opening of the interlocked adjusting valve is increased to increase the air supplementing flow, so that the moisture content of the chips at the outlet of the cooling section is maintained to be 500±50ppm.

[0121] The cooling nitrogen temperature is monitored in real time by the temperature control element 04. When the detected temperature deviates from the set value, the opening of the cooling water regulating valve 03 is interlocked and adjusted to maintain the nitrogen outlet temperature within the range of 35 to 55°C.

[0122] Process parameters: cooling and humidification air volume gas-to-solid ratio of 3.0 (ratio of cooling circulation nitrogen flow to chip flow), residence time of 4 hours, gas-to-solid ratio of nitrogen entering the reaction section after mixing of 2.0;

[0123] Effect: Slice moisture content 500±50ppm, temperature uniformity ±1℃, viscosity uniformity 3.4±0.02.

[0124] When producing slices with a moisture content requirement of 800±50ppm:

[0125] Air supply adjustment: increase the setting value of flow meter 07 to a gas-solid ratio of 0.1, and adjust the threshold of dew point detector 05 to -10℃;

[0126] Parameter adjustment: the ratio of cooling cycle nitrogen flow to slice flow was increased to 2.5, and the corresponding residence time was extended to 5 hours;

[0127] Effect: The moisture content of the slices is 790±20ppm, and the energy consumption is reduced by about 20% compared with adding a humidity control tower.

[0128] When producing slices with a moisture requirement of 500±50ppm:

[0129] Control optimization: The dew point detector 05 is set to an accurate value of -15°C, and the regulating valve 06 is controlled in PID mode;

[0130] Parameter combination: high dew point nitrogen supplementary air gas-to-solid ratio 0.05, cooling and humidification air volume gas-to-solid ratio 2.0, residence time 3.5 hours;

[0131] Effect: Moisture content 480±20ppm, CV value does not exceed 1.5%.

[0132] Example 2

[0133] for Figure 2 、 Figure 3 The working condition shown corresponds to a split structure, wherein the main differences from Example 1 are:

[0134] Equipment connection: The solid phase viscosity increasing reactor is connected to the cooling silo via a rotary feeding valve 13 or a straight pipe; the volume of the cooling silo is designed to be 0.2 times that of the reactor to meet the process residence time requirements.

[0135] Nitrogen circulation: The nitrogen discharged from the cooling silo nitrogen outlet 11 must first be mixed with the supplementary high dew point nitrogen, heated to 170°C by the nitrogen heater 08, and then returned to the reactor;

[0136] specific, and Figure 1 The difference is that in the reaction section of the solid-phase viscosity-increasing reactor, the viscosity-increasing slices from the solid-phase viscosity-increasing reactor pass through rotary feeding valve 13 and fall into the cooling silo, or directly through a straight-through pipe. The low-dew-point nitrogen from the cooling silo nitrogen outlet 11 is mixed with the high-dew-point nitrogen supplemented from the nitrogen treatment system after passing through regulating valve 06 and flowmeter 07. The nitrogen is then returned to the inlet of nitrogen heater 08 through the outlet of fan 01, heated, and then enters the viscosity-increasing reaction nitrogen cycle. The replenishing air volume is equal to the return air volume.

[0137] Example 3 Process flow for producing high viscosity nylon chips using the above system

[0138] Taking the integrated structure as an example, the corresponding Figure 1 . Device connection relationship:

[0139] The system includes an integrated solid-phase viscosity-increasing reactor, with the reaction section and cooling section connected via an internal tapered structure. A nitrogen outlet 09 is located at the top of the reaction section, connected to a nitrogen treatment system, and a nitrogen inlet 10 is located at the bottom, connected to a nitrogen heater 08. A nitrogen outlet 11 in the cooling section is connected in sequence to a cooling fan 01 and a nitrogen cooler 02, before returning to the cooling section through an air inlet 12.

[0140] Low-viscosity nylon chips (relative viscosity 2.4-2.7) enter the solid-phase viscosity-increasing reactor and are heated and viscosity-increasing by contact with high-temperature nitrogen. They then remain in the reaction section / reactor and fall through the reaction section's distribution cone into the cooling section. The viscosity-increasing chips are cooled by cold nitrogen in the cooling section and finally delivered to the storage and packaging section through the discharge port and discharger at the bottom of the cooling section cone.

[0141] The process of reactive viscosity increase of the low-viscosity nylon chips mentioned above has been described in detail in the utility model patent CN2021229495525. For the technical solution of the present invention, this process involves a new process, including the utilization of the reaction cycle nitrogen. The specific process is as follows:

[0142] After dehumidification and deoxygenation treatment, the reaction nitrogen gas coming out from the air outlet 09 at the top of the reactor passes through the nitrogen heater 08, the reaction section / reactor air inlet 10, and enters the nylon solid phase viscosity enhancement reaction section / reactor to undergo solid phase polycondensation reaction and recirculation.

[0143] The fresh high dew point nitrogen (dew point 10-30°C) supplied by the cooling and humidification in the cooling section is heated by the slices coming out of the reaction section / reactor, and then enters the reaction section / reactor through the nitrogen inlet 10. It is mixed with the fresh high dew point nitrogen at the bottom of the reaction section / reactor and then used for the normal solid phase viscosity increasing reaction. In order to ensure that the nitrogen heats or cools the slices more fully and evenly, the gas-to-solid ratio of the circulating nitrogen flow rate used in the reaction section / reactor to the slice flow rate is generally controlled at 2.0-4.0.

[0144] The gas-solid ratio of the nitrogen treated by the nitrogen treatment system to the slice flow rate in the reaction cycle is 1.5-3.0. By controlling the ratio, the humidity of the nitrogen during the reaction of the slice in the reaction section / reactor can be further controlled, so that the moisture content of the finished slice leaving the reaction section can be adjusted to be in the range of 0.02-0.06%.

[0145] The nitrogen leaving the cooling section is cooled and pressurized by the cooling fan 01 and the nitrogen cooler 02, and then enters the cooling section of the solid-phase tackifying reactor of the nylon through the cooling section air inlet 12 for circulation. Specifically, the nitrogen leaving the cooling section nitrogen outlet 11 first enters the cooling fan 01, and is sent to the nitrogen cooler 02 by the pressurization of the cooling fan 01. In the nitrogen cooler 02, the nitrogen is further cooled to a set temperature (for example, to 35-55°C). The cooled nitrogen then enters the dew point detector 05, which monitors the humidity of the nitrogen in real time. When the detected dew point is lower than the set threshold, the dew point detector 05 transmits a signal to the regulating valve 06, which adjusts the opening degree according to the signal to control the make-up air flow rate, so as to maintain the moisture content of the slice at the outlet of the cooling section within the set range. The adjusted nitrogen returns to the cooling section through the cooling section air inlet, and during the whole cooling cycle, the temperature control element 04 and the cooling water regulating valve 03 form a dynamic interlock to ensure that the temperature of the nitrogen entering the cooling section is stable within a fluctuation range of ±1°C, and one cycle is completed.

[0146] Similarly, Figure 2 、 Figure 3 Under the working condition, the high-dew-point nitrogen supplemented from the nitrogen treatment system and the low-dew-point nitrogen leaving the cooling bin nitrogen outlet 11 are mixed, and then return to the solid-phase tackifying nitrogen circulation system through the nitrogen fan 01, the nitrogen heater 08 and the nitrogen inlet 10.

[0147] The flow rate of the cooling water of the nitrogen cooler 02 is precisely controlled by the cooling water regulating valve 03, and the adjusting signal comes from the real-time monitoring data of the temperature control element 04 installed on the outlet pipeline of the cooling water regulating valve 03.

[0148] The gas-solid ratio of the cooling cycle nitrogen to the slice flow rate is generally controlled to be 2.0-4.0. The cycle adjusts the humidity of the slice by supplementing the high-dew-point nitrogen treated by the nitrogen treatment system, so as to adjust the final moisture content of the finished slice to be in the range of 0.04-0.1%.

[0149] Taking a 5000-ton / year high-viscosity nylon chip device as an example:

[0150] The solid-phase viscosity-increasing reactor of nylon chip components with a relative viscosity of 2.6 and water content of about 0.7% is filled and kept at a certain material level; the chip is in full contact with high-temperature reaction nitrogen at 170 DEG C, the temperature of the chip rises, the moisture is removed, and the polycondensation reaction is initiated; in the reaction section / reactor, the chip continues to carry out the polycondensation reaction under the action of fresh nitrogen at the bottom, and the molecular weight and viscosity increase accordingly; the viscosity-increased chip directly falls into the cooling section, is humidified to about 500 ppm by supplementing fresh nitrogen with a certain humidity in the cooling section, and is cooled to 40+ / -1 DEG C by circulating cold nitrogen, and is finally sent to the finished product storage or packaging section.

[0151] The moisture removed by the viscosity-increasing reaction is taken out from the air outlet 09 by the circulating nitrogen. As dehumidified nitrogen, it is removed of excess moisture by the nitrogen treatment system, the oxygen content of the nitrogen is reduced to below 1 ppm, and then heated to 170 DEG C by the nitrogen heater 08 before entering the nylon solid-phase viscosity-increasing reactor from the air inlet 10 of the reaction section for recirculation.

[0152] The nitrogen from the air outlet 11 of the cooling section is pressurized by the cooling fan and enters the nitrogen cooler to be cooled to 35-55 DEG C, and then enters the cooling section of the nylon solid-phase viscosity-increasing reactor from the air inlet 12 of the cooling section for recirculation.

[0153] The cooling water pipeline of the nitrogen cooler 02 is equipped with a cooling water regulating valve 03, and the temperature control element 04 installed on the outlet pipeline of the cooling water regulating valve 03 monitors the temperature of the nitrogen in real time, and the cooling nitrogen temperature is stably controlled at 38+ / -1 DEG C by PID adjustment.

[0154] Comparative Example 1

[0155] In order to verify the technical effect of the present application, a comparative test was carried out using the process equipment described in the utility model patent CN2021229495525.

[0156] This comparative example strictly follows the parameters of the original patent example: the cooling section uses fixed high dew point humidified nitrogen gas-solid ratio operation (actual value <0.2), without setting a high dew point nitrogen dynamic supplement system, the residence time is controlled at 2 hours and only used for cooling function, and the humidification air supplement process has no automatic response mechanism.

[0157] The test under the same production conditions shows that due to the unadjustable gas-solid ratio and insufficient residence time, the water content of the product fluctuates by ±100 ppm, and fine humidity control cannot be achieved; while the present application reduces the water content fluctuation to

[0158] ±50ppm, doubling the control accuracy and expanding the moisture adjustment range by 300%. This comparison reveals that existing technologies, lacking a collaborative parameter optimization mechanism, struggle to meet the demands of high-precision humidity control.

[0159] Comparative test data

[0160]

[0161] It is particularly important to point out that those skilled in the art have long believed that "extending the residence time will inevitably lead to a surge in energy consumption" and that "a fixed gas-to-solid ratio is a prerequisite for ensuring reaction stability." However, the present invention has made a breakthrough discovery: through the coordinated control of the dynamic gas-to-solid ratio and the graded residence time, it is possible to achieve "water content fluctuations reduced to ±50ppm and control accuracy increased by 1 times" under the premise of comparable energy consumption. This comprehensive performance improvement is a qualitative leap. This technical approach directly overturns the traditional perception that "high-precision control must rely on an independent humidification tower," and proves that ±50ppm-level control can also be achieved through integrated reactor optimization, overcoming the long-standing technical prejudice in the industry. In particular, the breakthrough in water content control accuracy from ±100ppm to ±50ppm is not an incremental improvement of the existing technology, but a qualitative leap.

[0162] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A nylon solid phase thickening cooling and humidification system, characterized in that: include: Solid phase viscosity increasing reaction unit, used for viscosity increasing treatment of nylon chips; A cooling unit is used to cool and humidify the nylon chips after viscosity increase; A circulating nitrogen control system is used to cooperate with the cooling unit to cool and humidify the nylon chips after viscosity increase, comprising: A gas circulation loop connecting the air outlet (11) and the air inlet (12) of the cooling unit; A cooling fan (01) is provided on the gas circulation loop; A nitrogen cooler (02) is connected to the outlet side of the cooling fan (01); A gas supply pipeline connects the gas circulation loop with an external nitrogen source for supplying nitrogen; A dew point detector (05) is provided in the gas circulation loop for monitoring gas humidity; A temperature control element (04) is provided at the outlet of the nitrogen cooler (02) for regulating the gas temperature; The solid-phase viscosity-increasing reaction unit and the cooling unit are of an integrated structure or a split structure, and the split structure is connected via a rotary feeding valve or a straight-through pipe to achieve material transmission between the solid-phase viscosity-increasing reaction unit and the cooling unit.

2. The system according to claim 1, wherein: The gas circulation loop: The cooling unit has an air outlet (11) connected to the inlet of the cooling fan (01) through a pipeline; The cooling fan (01) has its outlet connected to the inlet of the nitrogen cooler (02) through a pipeline; The nitrogen cooler (02), the outlet of which is connected to the cooling unit air inlet (12) via a pipeline; The air supply pipeline: The air supply pipeline is connected to the front section of the cooling fan (01) inlet; A regulating valve (06) and a flow meter (07) are sequentially arranged on the air supply pipeline to adjust the flow of the supplementary nitrogen.

3. The system according to claim 1, wherein: The outlet pipe of the nitrogen cooler (02) is provided with a dew point detector (05) and a temperature control element (04); A cooling water regulating valve (03) is provided on the cooling water inlet pipe of the nitrogen cooler (02).

4. The system according to claim 1, wherein: The dew point detector (05) is interlocked with the regulating valve (06); a dynamic feedback control system is formed, and the interlock control response time is ≤10 seconds to control the humidity of the circulating nitrogen; The temperature control element (04) is interlocked with the cooling water regulating valve (03) to form a dynamic feedback control system for controlling the temperature of the circulating nitrogen; The cooling fan (01) is a variable frequency controlled fan, and its motor is connected to a variable frequency controller; the variable frequency control is used to maintain a stable gas-to-solid ratio between the cooling cycle nitrogen flow and the slice flow.

5. A solid phase thickening, cooling and humidifying process for nylon chips using the system of claim 1, characterized in that: The following steps are involved: (1) Nylon chips with a relative viscosity of 2.4 to 2.7 are subjected to solid phase viscosity enhancement and then enter the cooling unit, where the chip temperature is reduced from the reaction temperature of 140 to 170°C to the same cooling inlet temperature; (2) fresh high dew point nitrogen with a dew point of 10 to 30° C. is drawn from the solid phase thickening nitrogen treatment system, measured by a flow meter (07), and controlled by a regulating valve (06) to be fed into the cooling unit, with the gas-solid ratio being dynamically adjusted within a range of 0.05 to 0.5; (3) The humidity of the circulating nitrogen is monitored in real time by a dew point detector (05). When the detection value deviates from a set threshold value within the range of -20 to 20°C, the interlocking regulating valve (06) adjusts the air supply flow rate within 10 seconds or less to ensure that the humidity of the cooling circulating nitrogen is within the set threshold value and maintain the moisture content of the slices at the outlet of the cooling unit within the set range; (4) By adjusting the cooling fan frequency, the ratio of the cooling cycle nitrogen flow rate to the slice flow rate (gas-solid ratio) is controlled to be 2.0-4.0; (5) Control the slices’ residence time in the cooling unit to be 1.5 to 6 hours. (6) The cooling water flow rate is adjusted by the cooling water regulating valve (03) to control the temperature of the cooling circulating nitrogen entering the cooling unit to be 20-60°C.

6. The process according to claim 5, characterized in that: By quantitatively supplementing high dew point nitrogen, adjusting the gas-solid ratio of cooling and humidification and the temperature of cooling nitrogen, the final moisture content of the finished slices is controlled within the range of 400 to 1000 ppm.

7. The process according to claim 5, characterized in that: When producing slices with a moisture content of 500±50ppm, the air-to-solid ratio is set to 0.05-0.1, the threshold of the dew point detector (05) is set to -15--5°C, the temperature of nitrogen entering the cooling unit is 40°C, and the ratio of the cooling cycle nitrogen flow to the slice flow is 2.0-3.

0.

8. The process according to claim 5, characterized in that: When producing slices with a moisture requirement of 500±50ppm, the control parameters include: (1) Dew point detector (05) setting value: -10±0.5℃; (2) Ratio of cooling cycle nitrogen flow to slicing flow: 2.5 ± 0.2; (3) Temperature of circulating nitrogen entering the cooling unit: 40±1℃; (4) Moisture content of finished slices: 500±50ppm, CV value ≤1.5%.

9. The process according to claim 5, characterized in that: When producing slices with a moisture content of 800±50ppm, the air-to-solid ratio is increased to 0.1-0.2, the threshold of the dew point detector (05) is adjusted to -10-0°C, the temperature of nitrogen entering the cooling unit is 40°C, and the ratio of the cooling cycle nitrogen flow to the slice flow is 2.0-3.

0.

10. The process according to claim 9, characterized in that: The ratio of the cooling cycle nitrogen flow rate to the slice flow rate is 3.0, and the residence time is 5 hours.

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