Methylamine separation and purification system and method

Abstract

The present application relates to the technical field of chemical separation, and discloses a methylamine separation and purification system and method, which can efficiently destroy hydrogen bond association system by accurately controlling flash evaporation pressure, temperature and material residence time, can recover the extraction water after removing trace organic impurities, can recover the extraction agent polarity and selectivity, can guarantee the stable separation efficiency of trimethylamine, can cut off the cross-unit pollution path from the source, can slow down the tower scaling and improve the mass transfer efficiency, can simultaneously match the whole process parameter monitoring system, can collect the operation parameters of each tower, product purity, impurity removal rate and hydrogen bond dissociation rate, can calculate the system running cycle and failure probability based on the data, and can propose the product purity stability and system energy consumption optimization strategy, so as to dynamically control the operation parameters of the whole link such as deamination, extraction, separation and recovery, and guarantee the stable output of high-purity methylamine product and the long-period continuous operation of the system.

Description

Technical Field

[0001] This invention relates to the field of chemical separation technology, and in particular to a methylamine separation and purification system and method. Background Technology

[0002] Methylamine, as an important organic chemical raw material, is widely used in pesticides, pharmaceuticals, dyes, rubber additives, water treatment agents, and many other fields. It is usually synthesized from methanol and ammonia under catalytic conditions. The reaction products often contain monomethylamine, dimethylamine, trimethylamine, as well as unreacted ammonia, methanol, and a small amount of water. In order to meet the demand of downstream industries for high-purity single methylamine products and to achieve efficient utilization and resource recovery of raw materials, methylamine separation and purification equipment has emerged. This type of equipment can achieve precise separation and purification of mixed methylamine components through mature combined processes such as distillation and extraction, providing key technical support for the stable operation of related chemical industry chains.

[0003] Regarding the above-mentioned and existing related technologies, the inventors believe that the following defects often exist: Existing technologies fail to consider the hydrogen bonding between trace organic impurities in the circulating extraction water and water molecules, and lack targeted removal methods. This results in a dynamic and irreversible decline in the selectivity of the extractant for trimethylamine, leading to a continuous decrease in trimethylamine separation efficiency, an increased risk of product contamination, and difficulty in maintaining stable high purity levels after long-term operation, failing to meet the stringent purity and stability requirements of high-end chemical industries. Furthermore, the technologies fail to identify the contaminant migration effect in the impurity enrichment zone of the dehydration tower, lack directional impurity removal channels, and ignore the risk of cross-unit material linkage contamination between the dehydration and extraction towers. This creates a coupled contamination loop involving impurity accumulation in the dehydration tower, contamination of the extraction water, adsorption of impurities by the tower packing, obstruction of mass transfer, and increased difficulty in impurity separation. Consequently, the mass transfer efficiency of the extraction tower is significantly reduced, tower scaling is accelerated, the continuous operation cycle of the system is shortened, and frequent adjustments to operating parameters are required to compensate for performance degradation, increasing operational complexity and resulting in large fluctuations and poor stability in product purity. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing technology has the following shortcomings: it does not consider the hydrogen bonding association between trace organic impurities in the circulating extraction water and water molecules, does not design targeted removal methods, does not identify the pollutant migration effect in the impurity enrichment zone of the dehydration tower, does not set up a directional impurity removal channel, and ignores the risk of cross-unit material linkage pollution between the dehydration tower and the extraction tower. To this end, we propose a methylamine separation and purification system and method.

[0005] To achieve the above objectives, this application adopts the following technical solution: a methylamine separation and purification system and method, comprising the following steps: Step 1: Obtain crude methylamine feedstock from methanol and ammonia catalytic synthesis and collect data, followed by impurity removal and preheating treatment; Step 2: Encrypt and transmit the data collected in Step 1 to the control terminal; Step 3: The control unit calculates the core parameters based on the transmitted data and adjusts the operating parameters of the deammoniation tower and extraction tower to achieve the separation of ammonia-trimethylamine azeotrope and the extraction of trimethylamine; Step 4: The control terminal commands the optimized dehydration tower to selectively extract impurities, and simultaneously controls the operation of the extraction water flash evaporation system to regenerate and circulate the extraction water; Step 5: Pass the mixed gas from the top of the dehydration tower into the separation tower, and adjust the separation tower parameters to achieve the fractional extraction of monomethylamine and dimethylamine; Step 6: Pass the residual liquid from the separation tower into the methanol recovery tower to recover methanol and circulate it, while simultaneously treating various waste liquids and flash gases; Step 7: Monitor the parameters and performance indicators of each unit in real time, and calculate the system operating cycle and failure probability; Step 8: Based on the monitoring data, propose adjustment strategies and dynamically optimize the operating parameters of each step.

[0006] Step 1, data acquisition, specifically involves collecting compositional data of monomethylamine, dimethylamine, trimethylamine, ammonia, methanol, water, and heavy component impurities in the crude methylamine raw material, as well as raw material temperature data.

[0007] The encrypted transmission in step 2 specifically involves transmitting the raw material composition data, raw material temperature data, and pretreatment process parameters collected in step 1 to the control terminal via a self-access communication protocol. Encryption technology is used during the transmission process to prevent data leakage and tampering.

[0008] The core parameters for step 3 are deammoniation efficiency and extraction selectivity coefficient; The specific adjustments to the operating parameters are: adjusting the reflux ratio and bottom temperature of the deammoniation tower, and the extraction water flow rate and feed rate of the extraction tower. The separation and extraction process involves distilling the ammonia-trimethylamine azeotrope from the top of the deammoniation tower and returning it to the synthesis section, while extracting trimethylamine from the top of the extraction tower.

[0009] Step 4, targeted impurity removal, specifically involves the control unit instructing the optimized dehydration tower to selectively extract heavy component impurities from the impurity enrichment area based on the impurity enrichment status within the tower. Extraction water regeneration specifically involves controlling the flash evaporation system of extraction water to operate under preset pressure and temperature conditions, so that the material maintains a suitable residence time to break the hydrogen bond association system between trace organic impurities and water molecules in the extraction water. After removing trace organic impurities, the extraction water is cooled to a temperature that meets the process requirements and returned to the extraction tower for recycling.

[0010] Step 5, the fine separation of methylamine, specifically involves introducing a monomethylamine-dimethylamine mixture from the top of the optimized dehydration tower into the separation tower, adjusting the separation tower to a suitable operating pressure and reflux ratio at the control end, collecting monomethylamine from the top of the tower, and collecting dimethylamine from the side line position corresponding to the theoretical plate of the tower body.

[0011] Step 6, methanol recovery, specifically involves feeding the residue from the bottom of the separation tower into the methanol recovery tower, controlling the tower to the corresponding operating pressure and reflux ratio, recovering the methanol therein, and recycling it to the synthesis section. Specifically, the wastewater treatment involves introducing the side-stream extract from the optimized dehydration tower, a portion of the bottom liquid, and the flash gas from the extraction water flash evaporation system into the wastewater treatment unit, and controlling the washing liquid to an appropriate circulation ratio.

[0012] Step 7, real-time monitoring, specifically involves monitoring the operating parameters of each tower, product purity, impurity removal rate, and hydrogen bond dissociation rate, and calculating the continuous operating cycle of the system and the probability of equipment failure.

[0013] Step 8, the optimization scheduling, specifically involves proposing adjustment strategies based on the system operation data from step 7, targeting product purity stability and system energy consumption, and dynamically optimizing the operating parameters of each stage, such as deammoniation, extraction, separation, and recovery.

[0014] A methylamine separation and purification system includes a raw material pretreatment unit, a data acquisition and transmission unit, a separation tower unit, an auxiliary processing unit, and a control and monitoring unit; The raw material pretreatment unit includes a precision filter and a plate heat exchanger, used to remove solid impurities from the raw materials and preheat them; The data acquisition and transmission unit includes a concentration sensor, a temperature sensor, and a data transmission module, which are used to acquire raw material data and process parameters and transmit them in encrypted form. The separation tower unit includes a deammoniation tower, an extraction tower, an optimized dehydration tower, a separation tower, and a methanol recovery tower, used to achieve graded separation and resource recovery of methylamine; The auxiliary treatment unit includes an extract water flash evaporation system and a wastewater treatment unit, which are used to purify the circulating extract water and treat wastewater. The control and monitoring unit includes a control module, a monitoring and management module, and an optimization and scheduling module, which are used to receive data, calculate parameters, issue control commands, monitor operating status, and optimize scheduling.

[0015] The technical effects and advantages of this invention are as follows: This invention addresses the problem of dynamic and irreversible decline in the selectivity of the extractant for trimethylamine caused by hydrogen bonding between trace organic impurities in the circulating extraction water and water molecules. A flash evaporation regeneration mechanism for the extraction water is designed. By precisely controlling the flash evaporation pressure, temperature, and material residence time, the hydrogen bonding system is efficiently disrupted. After removing trace organic impurities, the extraction water is cooled and refluxed back to the extraction tower for reuse, simultaneously restoring the polarity and selectivity of the extractant and ensuring stable trimethylamine separation efficiency. Furthermore, this invention addresses the coupled pollution loop caused by contaminant migration in the impurity enrichment zone of the dehydration tower, resulting in impurity accumulation in the dehydration tower, extraction water contamination, impurity adsorption by the packing material, hindered mass transfer, and difficulty in impurity separation. This is achieved by targeting the impurity enrichment zone in the dehydration tower. The system incorporates directional impurity removal channels to precisely and directionally remove heavy component impurities, cutting off cross-unit contamination pathways at the source, mitigating tower scaling, and improving mass transfer efficiency. Simultaneously, a comprehensive parameter monitoring system collects real-time data on tower operating parameters, product purity, impurity removal rate, and hydrogen bond dissociation rate. Based on this data, the system's operating cycle and failure probability are calculated, leading to targeted optimization strategies for product purity stability and system energy consumption. This dynamically adjusts operating parameters across all stages, including deammoniation, extraction, separation, and recovery, achieving synergistic linkage between two core innovative mechanisms and comprehensive process optimization scheduling. Ultimately, this ensures high-purity and stable production of methylamine and long-term continuous system operation. Attached Figure Description

[0016] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts: Figure 1 This is a schematic flowchart of a method for separating and purifying methylamine according to the present invention. Figure 2 This is a schematic diagram of a methylamine separation and purification system according to the present invention; Figure 3 This is a flowchart illustrating the sub-modules of the data acquisition and transmission unit and the control and monitoring unit of the present invention. Detailed Implementation

[0017] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0018] Reference Figure 1-3 As shown, the present invention provides a technical solution: a methylamine separation and purification system and method, comprising the following steps: Step 1: The crude methylamine raw material, synthesized from methanol and ammonia, is received through a closed pipeline from the synthesis section (the core production stage where methanol and ammonia are used as raw materials to produce a crude methylamine mixture through catalytic reaction; it is the pre-reaction unit of the entire methylamine production process). The raw material contains monomethylamine, dimethylamine, trimethylamine, unreacted ammonia, methanol, water produced by the reaction, and a small amount of heavy component impurities. The content of each component in the raw material is collected using an online component analyzer with a detection accuracy of ±0.1wt%. At the same time, the temperature of the raw material is collected in real time using a temperature sensor, and the initial concentration of heavy component impurities is recorded using an impurity concentration detector. After the data collection is completed, the raw material first enters a filter with a filtration accuracy of 5μm. The filter is made of stainless steel and has a built-in replaceable filter element. This physical interception removes mechanical impurities such as solid particles and catalyst debris entrained in the raw material, preventing these impurities from adhering to the packing or tray surface after entering the subsequent towers, which could lead to a decrease in mass transfer efficiency or equipment blockage.

[0019] The filtered raw material then enters a plate heat exchanger made of 316L stainless steel, with a heat exchange area designed to be 50-80 mm depending on the throughput. By using low-pressure steam as the heating medium, the raw material temperature is precisely preheated to 45-50℃. The core purpose of preheating is to reduce the contact between the raw material and subsequent dewatering processes. The temperature difference inside the ammonia tower reduces the problem of uneven gas-liquid distribution caused by sudden temperature changes after the raw material enters the deammoniation tower, while also increasing the volatility of the raw material, creating conditions for the rapid separation of ammonia and methylamine in the deammoniation process.

[0020] After precision filtration, the solid impurity content in the raw material is reduced to below 0.001 wt%, reducing the risk of blockage in subsequent towers by more than 90%, and extending the equipment maintenance cycle from one month in the existing technology to more than six months. Through preheating treatment, the raw material can quickly reach distillation equilibrium after entering the deammoniation tower, shortening the start-up and stabilization time of the deammoniation tower from 2 hours to 30 minutes. At the same time, the heat load of the deammoniation tower reboiler is reduced, and the steam consumption per ton of raw material is reduced by 5-8 kg.

[0021] Step 2: The data collected in Step 1, such as the content of raw material components, impurity concentration, and raw material temperature, as well as the equipment operating status data, such as the inlet and outlet pressure difference of the precision filter and the inlet and outlet temperatures of the plate heat exchanger, are transmitted via the MQTT fast self-access communication protocol. This protocol is lightweight and has low latency, with data transmission latency controlled within 50ms, which can meet the needs of real-time control. It also supports the rapid access and disconnection of equipment, adapting to equipment maintenance and switching scenarios during production.

[0022] To ensure data security, SSL / TLS 1.3 encryption technology is used during transmission to perform end-to-end encryption of the data. The key length is ≥256 bits, which effectively prevents the data from being stolen, tampered with, or forged in the transmission link. The data transmission terminal is equipped with a built-in cache module with a cache capacity of 8GB. When the network experiences a brief interruption, it can temporarily store the collected data for 24 consecutive hours and automatically retransmit it after the network is restored, ensuring the integrity of the data and avoiding inaccurate decision-making at the control end due to network fluctuations.

[0023] The data transmission success rate reached 99.99%, with no data loss or tampering. The deviation between the data received by the control terminal and the data collected on site was ≤ ±0.2%, providing a reliable guarantee for the precise control of subsequent processes. The caching module effectively addressed the problem of unstable network in industrial sites. Even if a network interruption of less than 30 minutes occurred, the system could still maintain stable operation based on the cached data, avoiding interruptions in the production process.

[0024] Step 3: After receiving the data transmitted by S2, the control terminal first calculates the ammonia removal efficiency according to the formula. ; in, This indicates the initial concentration of ammonia in the crude methylamine feedstock. The concentration of ammonia in the bottom liquid of the deammoniation tower is indicated by real-time monitoring using an online concentration detector. Based on the evaluation results of the ammonia removal efficiency, the control end automatically adjusts the operating parameters of the ammonia removal tower: when the ammonia removal efficiency is higher than 97%, the current reflux ratio of 3.5-4.0 and the tower bottom temperature of 105-115℃ are maintained; when the ammonia removal efficiency is lower than 97%, the reflux ratio or tower bottom temperature of the ammonia removal tower is automatically increased until the ammonia removal efficiency recovers to above the threshold.

[0025] The deammoniation tower adopts a sieve tray tower structure with 30-35 trays and a tray spacing of 0.4m. The raw material enters from the middle of the tower and comes into full contact with the rising gas phase inside the tower. The boiling point of ammonia (-33.3℃) is much lower than that of methylamines. Under the action of distillation, ammonia and a small amount of trimethylamine form an azeotrope and evaporate from the top of the tower. After being cooled to 30-35℃ by the top condenser, 30-40% of it is refluxed to the top of the deammoniation tower to maintain the distillation balance in the tower. The remaining 60-70% is returned to the synthesis section for recycling through pipelines. The ammonia content in the bottom liquid of the tower after deammoniation is ≤0.5wt%. It is transported to the extraction tower by a variable frequency pump. During the transportation process, the flow rate is monitored in real time by a flow sensor with a control accuracy of ±0.5m³ / h. The extraction tower in this invention adopts a packed tower structure.

[0026] The ammonia removal efficiency is consistently maintained above 97%, and the ammonia content in the bottom liquid is controlled below 0.5 wt%, completely avoiding interference from ammonia in subsequent extraction processes. This ensures the selective separation effect of the extraction tower on trimethylamine, with an unreacted ammonia recovery rate of over 98%. The ammonia feed consumption per ton of methylamine product is reduced by 10-15 kg, significantly lowering production costs. Through automatic adjustment of operating parameters, the operational stability of the ammonia removal tower is greatly improved, and the fluctuation range of ammonia content in the bottom liquid is reduced from ±0.3 wt% to ±0.05 wt%.

[0027] Step 4: Based on the received raw material data and the bottom liquid data of the deammoniation tower, the control unit calculates the extraction selectivity coefficient according to the formula: ; in, This indicates the gaseous mole fraction of trimethylamine at the top of the extraction column. This indicates the liquid phase mole fraction of trimethylamine in the bottom of the extraction column. This indicates the total gaseous mole fraction of monomethylamine and dimethylamine at the top of the extraction column. The total liquid phase molar fraction of monomethylamine and dimethylamine in the bottom of the extraction tower is represented by the extraction selectivity coefficient, which is calculated by real-time monitoring of the component molar fractions at the top and bottom of the tower using an online gas chromatograph.

[0028] Based on the calculated extraction selectivity coefficient, the control unit automatically adjusts the extraction process parameters. When the extraction selectivity coefficient is higher than 2.6, the current extraction water flow rate and extraction tower operating temperature are maintained. When the extraction selectivity coefficient is below 2.6, first adjust the extraction water temperature to 60±2℃. If the coefficient still does not meet the standard after adjustment, increase the extraction water flow rate until the coefficient recovers to above the threshold.

[0029] The extraction tower adopts a packed tower structure, filled with corrugated metal perforated plate packing, with a specific surface area of ​​250-300 m². 2 / m 3 The packing height is 15-20m to ensure sufficient contact between the gas and liquid phases. The bottom liquid of the deammoniation tower enters from the middle of the extraction tower, and the extraction water enters from the top of the extraction tower. The gas and liquid phases contact countercurrently in the tower. Since the solubility of trimethylamine in water is significantly lower than that of monomethylamine and dimethylamine, trimethylamine is separated from the gas phase under the selective action of the extraction water. It is discharged from the top of the tower with the gas phase. After being cooled to 25-30℃ by the condenser, 70-80% is sent to the storage tank as trimethylamine product, and 20-30% is refluxed to the top of the extraction tower to maintain the extraction balance in the tower. The bottom liquid is sent to the optimized dehydration tower by the transfer pump.

[0030] The extraction selectivity coefficient is consistently maintained above 2.6, the extraction rate of trimethylamine reaches over 99.2%, and the purity of the trimethylamine product collected from the top of the tower is ≥99.3wt%, which is 0.3-0.5 percentage points higher than the existing technology. By automatically adjusting the extraction water flow rate and temperature, the system can adapt to fluctuations of ±3wt% in the trimethylamine content of the raw material, and the product purity fluctuation range is ≤±0.1wt%, significantly improving stability. The use of a packed tower improves the gas-liquid mass transfer efficiency, the tower diameter of the extraction tower is reduced by 20% compared with the traditional sieve plate tower, and the equipment footprint is reduced by 30%.

[0031] Step 5: First, through AspenPlus process simulation and on-site experiments, the enrichment area of ​​heavy component impurities in the optimized dehydration tower is determined, corresponding to 60-70% of the tower height. The impurity concentration in this area is 3-5 times that in the raw material, which is the key location for directional impurity removal. A side stream outlet is set in this area, equipped with an electric regulating valve, and an online concentration detector is installed to monitor the impurity concentration at the side stream outlet in real time.

[0032] Based on the monitoring data from the online concentration detector, the control unit automatically controls the extraction rate of the side-stream extraction device: when the impurity content exceeds 500 ppm, the electric valve automatically increases the opening, raising the extraction rate to 8% of the feed rate to the dehydration tower; when the impurity content is below 300 ppm, the electric valve automatically decreases the opening, reducing the extraction rate to 5% of the feed rate to the dehydration tower. Under normal operating conditions, the extraction rate remains stable between 5% and 8%. The impurity-containing material extracted from the side-stream is transported to the wastewater treatment unit through a dedicated pipeline to avoid mixing with other materials and causing secondary pollution.

[0033] The optimized dehydration tower adopts a sieve tray tower structure with 40-45 trays, an operating pressure of 0.65-0.75 MPa, a top temperature of 95-105℃, and a bottom temperature of 115-125℃. The bottom liquid of the extraction tower enters from the middle of the dehydration tower. Under the action of distillation, water and methylamine substances are separated. The methylamine substances are discharged from the top of the tower to the separation tower, while heavy component impurities are selectively extracted in the enrichment zone.

[0034] The targeted removal rate of heavy component impurities reaches over 99%, and the impurity content in the bottom liquid of the dehydration tower is reduced to below 0.05wt%, completely cutting off the migration path of impurities to the extraction tower. The impurity adsorption on the surface of the extraction tower packing is reduced from 5-8 mg / cm² per month in the existing technology to below 1 mg / cm², and the mass transfer coefficient is maintained above 0.75 kmol / (m³·h), which is 30% higher than the existing technology. The scaling cycle of the dehydration tower and extraction tower is extended from 3-6 months to 10-12 months, the equipment cleaning frequency is greatly reduced, and the maintenance cost is reduced by 60%.

[0035] Step 6: 90% of the liquid in the bottom of the optimized dehydration tower is introduced into the flash evaporation system through pipelines. The core equipment of the flash evaporation system is a vertical flash tank with a volume of 10-15 m³. The tank is equipped with 3-4 baffles to extend the material residence time. It also has multiple layers of porous media. The porous media is made of metal-organic framework material with a horizontal pore size >216 nm and a vertical pore size of 114-162 nm. This structure allows the material to pass through quickly while also intercepting trace impurities.

[0036] The control unit monitors the operating conditions inside the flash tank in real time using temperature and pressure sensors, precisely controlling the flash pressure to 0.12-0.18 MPa, the flash temperature to 82-88℃, and the material residence time in the tank to 12-14 minutes. Under these conditions, the input heat energy effectively breaks down the hydrogen bonding between methylamine-water molecules and methanol-water molecules, causing trace organic impurities to desorb from the water and be discharged as gas from the top of the flash tank. These gaseous impurities are then transported through pipelines to the wastewater treatment unit for washing.

[0037] The purified extract water is discharged from the bottom of the flash tank and sequentially enters a primary plate heat exchanger and a secondary plate heat exchanger for cooling. The primary heat exchanger uses circulating water as the cooling medium to reduce the extract water temperature from 82-88℃ to 72-74℃. The secondary heat exchanger uses low-temperature chilled water as the cooling medium to further reduce the extract water temperature to 60±2℃, ensuring that the temperature of the extract water entering the extraction tower meets the process requirements. The cooled extract water is then pressurized to 1.2-1.4MPa by a variable frequency extraction water pump and transported to the upper part of the extraction tower for recycling.

[0038] The dissociation rate of the hydrogen-bonded association system reaches over 99%, the effective dielectric constant of the extraction water recovers from 65-70 to over 76, and the extraction selectivity coefficient is stably maintained above 2.6, completely solving the problem of irreversible decline in extraction selectivity in existing technologies; the recycling rate of extraction water reaches over 90%, the fresh water replenishment is reduced by 60% compared to existing technologies, and the fresh water consumption per ton of methylamine product is reduced from 5-8 m³ / ton. 3 Reduced to 2m 3 The flash evaporation system has lower energy consumption, with a processing energy consumption of only 50-80 kJ per ton of extracted water, which is more than 70% lower than the traditional distillation purification method.

[0039] Step 7: Based on the separation requirements of monomethylamine and dimethylamine, and combined with the content ratio of the two components in the raw materials, the control end calculates the reflux ratio and side stream sampling location coefficient of the separation tower. The calculation of the reflux ratio is based on the product purity as the core objective. The purity requirement for monomethylamine is ≥99.8wt%, and the purity requirement for dimethylamine is ≥99.5wt%. On this basis, the optimal reflux ratio range is determined to be 12-14 through simulation calculation. The side stream sampling location coefficient is determined based on the enrichment area of ​​dimethylamine in the separation tower. The optimal value corresponds to the 10th-12th theoretical plate of the tower body. This position can minimize the mutual entrainment of monomethylamine and dimethylamine.

[0040] The separation tower adopts a sieve tray structure with 40-45 trays, an operating pressure of 0.75-0.85 MPa, a top temperature of 55-65℃, a side stream temperature of 62-68℃, and a bottom temperature of 100-110℃. The monomethylamine-dimethylamine mixture at the top of the optimized dehydration tower enters from the middle of the tower. Under distillation, monomethylamine, with a boiling point of 33.5℃, evaporates from the top due to its lower boiling point. After being cooled to 20-25℃ by a condenser, 40-50% is refluxed to the top of the separation tower to maintain distillation balance within the tower, and 50-60% is sent to a dedicated storage tank as monomethylamine product. Dimethylamine, with a boiling point of 6.9℃, accumulates in the middle of the tower and is collected from the side stream outlet. After being cooled to 25-30℃ by a cooler, it is sent to the storage tank as dimethylamine product. The bottom residue, containing methanol, water, and trace amounts of methylamine, is transported to a methanol recovery tower via pipeline.

[0041] The purity of monomethylamine is consistently above 99.8 wt%, with a maximum of 99.9 wt%, while the purity of dimethylamine is consistently above 99.5 wt%, with a maximum of 99.7 wt%, both meeting the stringent requirements of high-end pharmaceuticals and pesticides. The yield of both products reaches over 98.5%, an improvement of 1-2 percentage points compared to existing technologies. By precisely controlling the reflux ratio and the side-stream sampling location, the product purity fluctuation range is ≤ ±0.08 wt%, significantly improving batch stability and solving the problem of large product purity fluctuations in existing technologies.

[0042] Step 8: The control unit calculates the methanol recovery rate using a formula based on the initial methanol content in the feed and the detected methanol content in the residue at the bottom of the separation tower. ; in, For the quality of the recovered methanol, This represents the initial mass of methanol in the feedstock. Based on the calculated methanol recovery rate, the control unit automatically adjusts the operating parameters of the methanol recovery tower. When the recovery rate is below the set threshold of 98%, the reflux ratio or the bottom temperature of the recovery tower is increased; when the recovery rate is above 98%, the current operating parameters are maintained.

[0043] The methanol recovery tower adopts a sieve tray tower structure with 25-30 trays. The tower bottom is equipped with a reboiler and low-pressure steam heating. The tower top is equipped with a condenser and circulating water cooling. The residue in the bottom of the separation tower enters from the middle of the recovery tower. Under the action of distillation, methanol (boiling point 64.7℃) is separated from water and distilled off from the top of the tower. After being cooled to 30-35℃ by the condenser, methanol with a purity ≥95wt% is obtained. It is then transported through pipeline to the batching tank of the synthesis section and recycled for the methylamine synthesis reaction. The bottom wastewater is transported through pipeline to the wastewater treatment unit.

[0044] The methanol recovery rate is consistently maintained above 98%, reaching a maximum of 99%. Methanol consumption per ton of methylamine product is reduced by 8-12 kg, raw material costs are reduced by 5-8%, and the recovered methanol purity is ≥95wt%. It can be directly used in the synthesis reaction without additional purification, and the recycling rate reaches over 95%. The operating energy consumption of the recovery tower is low, with the energy consumption for recovering one ton of methanol being only 100-150 kJ. Compared with purchasing methanol separately, the overall cost is reduced by more than 60%.

[0045] Step 9: The control unit monitors the effluent COD value of the wastewater treatment unit in real time using a COD detector and calculates the wastewater treatment compliance rate = emission standard COD value - actual effluent COD value / emission standard COD value × 100%, where the emission standard COD value is set to 100 mg / L. Based on the calculated compliance rate, the control unit automatically adjusts the washing liquid circulation ratio of the wastewater treatment unit. When the compliance rate is lower than the set threshold of 95%, the washing liquid circulation ratio is increased from 1.5 to 2.0; when the compliance rate is higher than 95%, the circulation ratio is maintained between 1.5 and 2.0.

[0046] The wastewater treatment unit mainly includes a wastewater tower and a biological treatment tank. The side-stream effluent from the optimized dehydration tower, the 10% bottom liquid, and the flash gas from the flash evaporation system are all introduced into the wastewater tower. The wastewater tower adopts a packed tower structure, filled with ceramic packing. The washing liquid is the effluent from the biological treatment tank, which is circulated and sprayed through a circulating pump. Impurity-laden gases come into full contact with the washing liquid inside the wastewater tower, and trace amounts of impurities such as methylamine and methanol are absorbed by the washing liquid. After preliminary treatment in the wastewater tower, the wastewater containing impurities is transported to the biological treatment tank, where organic matter is further removed through processes such as aeration and microbial degradation.

[0047] The wastewater treatment compliance rate is consistently above 95%, with the final effluent COD ≤ 100 mg / L, and under some operating conditions, it can be as low as below 50 mg / L, fully meeting environmental emission requirements. The removal rate of trace impurities in flash gas reaches over 99%, reducing the risk of fugitive emissions by 95%. The wastewater reuse rate reaches over 30%, and some washing liquid can be recycled, further reducing fresh water consumption and wastewater discharge. The wastewater tower adopts a packed tower structure, treating wastewater containing impurities through washing and absorption. The wastewater tower features circulating spray of washing liquid and a packing mass transfer structure.

[0048] Step 10: The monitoring system is equipped with sensors for temperature, pressure, flow rate, and liquid level in each key piece of equipment, such as the deammoniation tower, extraction tower, dehydration tower, separation tower, and flash tank. These sensors collect the operating parameters of the equipment in real time, and their measurement accuracy meets industrial-grade standards. In addition, online purity detectors are installed at the inlet of each product storage tank to monitor the purity of trimethylamine, monomethylamine, and dimethylamine in real time. Online impurity detectors are installed on the material pipelines of each process to monitor the impurity content in real time.

[0049] The monitoring system uploads all collected data to the central monitoring platform in real time. The platform uses an industrial touchscreen as the display terminal, which displays the overall operating status of the system, equipment parameter change curves, product purity data, impurity content data, and other information through a visual interface. Simultaneously, it calculates the system's continuous operating cycle based on the collected data. ; in, Total system uptime This represents the total downtime. The formula for calculating the probability of equipment failure is: ; in The average number of failures per unit time is given, where T is the continuous running time, and is updated in real time on the interface.

[0050] It achieves comprehensive and real-time monitoring of system operation status with no blind spots. The acquisition frequency of equipment parameters and product data reaches 1 time / second, which can promptly detect parameter anomalies. The calculation accuracy of the continuous operation cycle of the system is ≤±1 hour, and the prediction accuracy of the probability of equipment failure reaches more than 85%, providing a reliable basis for preventive maintenance. The visualization display of the central monitoring platform enables operators to quickly grasp the system operation status, reducing the difficulty of operation by 50%.

[0051] Step 11: The monitoring system has preset alarm thresholds for each process parameter. When an abnormal parameter is detected, the system immediately triggers an audible and visual alarm and displays the abnormal location, abnormal parameter, and suggested handling measures on the central monitoring platform. For abnormal parameters that can be automatically adjusted, the control terminal automatically starts the adjustment program to adjust the operating parameters of the corresponding equipment until the abnormality is resolved. For abnormalities that cannot be automatically adjusted, the system locks the abnormal unit to avoid affecting the normal operation of other processes, and at the same time notifies the operators to handle the situation on-site.

[0052] In the event of equipment failure, the system uses a fault diagnosis algorithm to initially determine the cause of the failure and records information such as the time of occurrence, location of the failure, and parameter changes before and after the failure, providing maintenance personnel with a basis for repair. After receiving notification, maintenance personnel can quickly locate the fault point based on the information provided by the system and carry out targeted repairs. After the repairs are completed, the system performs parameter calibration and trial operation, and resumes normal production after confirming that there are no abnormalities.

[0053] The response time for abnormal parameters is ≤1 second, the success rate of automatic adjustment reaches over 90%, the abnormal handling time is reduced from 30 minutes in the existing technology to less than 5 minutes, the diagnostic accuracy of equipment faults reaches over 80%, maintenance time is reduced by 40%, and downtime caused by faults is reduced by 60%. By locking abnormal units, the overall production interruption caused by the escalation of faults is avoided, and the operational safety and continuity of the system are significantly improved.

[0054] Step 12: Optimize the built-in PID control algorithm and machine learning model of the scheduling system. By analyzing real-time collected raw material composition data, equipment operating parameters, product quality data, energy consumption data, etc., and combining them with historical operating data, an optimized scheduling strategy is generated. For example, when the content of heavy component impurities in the raw materials continues to rise, the system automatically adjusts the preset threshold of the side-stream output of the optimized dehydration tower from 5% to 6% to prevent impurity accumulation in advance. When the system energy consumption is higher than the set value, the reflux ratio of the deammoniation tower and the separation tower is optimized to reduce steam consumption while ensuring product purity. When the product purity requirements change, the system automatically adjusts the reflux ratio and operating temperature of the separation tower to meet the new quality requirements.

[0055] After the optimized scheduling strategy is generated, it is sent to each execution unit through the control terminal. At the same time, a system optimization report is generated, which includes information such as parameter comparison before and after optimization, changes in product purity, changes in energy consumption, and changes in equipment operating status. This report is sent to the central monitoring platform and management personnel terminals, so that management personnel can understand the optimization effect and formulate subsequent production plans and maintenance schemes.

[0056] The system's energy consumption was reduced by 5-10% compared to before optimization. The comprehensive energy consumption per ton of methylamine product decreased from 10,000-12,000 kJ to 8,000-9,000 kJ. The stability of product purity was further improved, with fluctuation range ≤ ±0.05 wt%. The mean time between failures of the equipment was extended by 20-30%, and the overall operating efficiency of the system was improved by 15-20%. The optimization report provided managers with comprehensive decision-making basis, and the scientific nature and accuracy of production management were significantly improved.

[0057] In the methylamine separation and purification system and method of the present invention, the core towers such as the deammoniation tower, extraction tower, optimized dehydration tower, separation tower, methanol recovery tower, and wastewater tower, as well as the supporting components / equipment such as precision filters, plate heat exchangers, variable frequency pumps and valves, sensors, online detectors, data transmission and control equipment, have all had their individual structural forms, basic working principles and conventional parameter ranges disclosed in the prior art.

[0058] The methylamine separation and purification system of the present invention includes a raw material pretreatment unit, a data transmission unit, a control unit, an execution unit, a monitoring unit, and an optimization scheduling unit. Each unit works together to complete the methylamine separation and purification process. The specific implementation and effects of each unit are described in detail below.

[0059] The raw material pretreatment unit is the center of raw material purification and optimization in the system. It mainly consists of a precision filter and a plate heat exchanger. Its core function is to remove solid impurities from the raw materials and preheat them to provide qualified raw materials for subsequent processes.

[0060] The precision filter features a stainless steel housing and a built-in replaceable ceramic filter element with a filtration accuracy of 5μm. Pressure sensors at the inlet and outlet monitor the filtration pressure difference in real time. When the pressure difference exceeds 0.1MPa, the system automatically issues a filter element cleaning or replacement prompt to prevent filter element blockage leading to reduced flow or raw material contamination. The plate heat exchanger has a detachable structure for easy cleaning and maintenance. The heat exchange plates feature a corrugated design to improve heat exchange efficiency. The heat exchange medium is low-pressure steam, and the heating temperature is precisely controlled by a temperature control valve to ensure the raw material is preheated to 45-50℃.

[0061] After processing, the raw materials have a solid impurity content of ≤0.001wt% and a temperature fluctuation of ≤±1℃, providing stable and clean raw materials for subsequent processes. The design of detachable heat exchangers and replaceable filter elements reduces maintenance difficulty and cost, and extends the maintenance cycle to more than 6 months. The unit's processing capacity can be adjusted according to the production scale, adapting to a raw material processing volume of 50-100m³ / h, making it highly versatile.

[0062] The data transmission unit is the information transmission bridge of the system. It mainly consists of a data acquisition module, a transmission module, and a buffer module. Its core function is to collect and safely and in real time transmit raw material data and equipment operating status data.

[0063] The data acquisition module connects to various sensors and detectors, supporting multi-channel data acquisition at a frequency of 1 time per second to ensure real-time data transmission. The transmission module uses the MQTT protocol and SSL / TLS 1.3 encryption technology, with a data transmission latency of ≤50ms and an encryption key length of ≥256 bits, ensuring fast and secure data transmission. The cache module has a built-in 8GB storage chip, which can store 24 hours of continuous data acquisition. It automatically caches data when the network is interrupted and automatically retransmits it after the network is restored, ensuring data integrity.

[0064] The data acquisition accuracy reached 99.9%, and the transmission success rate reached 99.99%. There were no cases of data loss, tampering, or leakage. The caching module effectively addressed the problem of unstable networks in industrial settings, ensuring that the system could still operate normally when the network fluctuated. The unit supports simultaneous transmission of multiple devices and multiple parameters, adapting to the needs of large-scale production and exhibiting strong scalability.

[0065] The control unit is the decision-making and control center of the system. It mainly consists of an industrial-grade PLC controller, an algorithm module, and an instruction output module. Its core functions are to receive data, calculate process parameters, generate control instructions, and send them to the execution unit.

[0066] The industrial-grade PLC controller uses a high-performance processor with a processing speed of ≥1GHz, supports multi-task parallel processing, and can quickly process massive amounts of acquired data. The algorithm module has built-in calculation algorithms for parameters such as deammoniation efficiency, extraction selectivity coefficient, and methanol recovery rate, as well as PID control algorithms. It can quickly generate optimized control instructions based on the data calculation results. The instruction output module adopts a high-precision signal output interface, with control signal output accuracy ≤±0.1%, ensuring that the execution unit accurately executes the instructions.

[0067] The generation time of control commands is ≤100ms, and the accuracy of command execution reaches 99.9%, realizing precise control of the entire process. The adoption of PID control algorithm enables the system to quickly adapt to raw material fluctuations and parameter changes, significantly improving control stability. The unit has strong anti-interference ability and can operate stably in the complex electromagnetic environment of industrial sites without command distortion or erroneous output.

[0068] The execution unit is the operation center of the system. It mainly consists of a deammoniation tower, an extraction tower, an optimized dehydration tower, a flash evaporation system, a separation tower, a methanol recovery tower, a wastewater treatment unit, and supporting pumps, valves, and heat exchangers. Its core function is to execute the instructions issued by the control unit and complete the specific separation and purification operations.

[0069] Each tower adopts an industrial-grade standard design, with 316L stainless steel or carbon steel lining, which is corrosion-resistant, high-temperature resistant, and pressure-resistant. The pumps and valves adopt frequency conversion control, with high accuracy in flow and pressure regulation. The flash evaporation system has built-in multi-layer porous media and baffles to enhance the hydrogen bond breaking and impurity removal effect. The wastewater treatment unit adopts a combination process of wastewater tower and biological treatment pond to ensure that wastewater meets discharge standards. All equipment is connected by pipelines with flange connections for easy installation and maintenance.

[0070] Each piece of equipment has high operational precision and can accurately execute the instructions of the control unit. The control error of process parameters is ≤±1%. The equipment has strong operational stability, with an average fault-free operating time of ≥8000 hours. The corrosion resistance and high temperature resistance of the towers and pipelines meet production requirements, with a service life of ≥10 years. The selection of supporting equipment is reasonable, with low energy consumption and high efficiency, which reduces the overall operating cost of the system.

[0071] The monitoring unit is the center for system operation monitoring and safety assurance. It mainly consists of sensors, detectors, a central monitoring platform, and alarm modules. Its core function is to monitor the system's operating status in real time and promptly alarm when abnormalities are detected.

[0072] Sensors and detectors cover all critical locations in the system, with measurement accuracy reaching industrial-grade standards. They can comprehensively and accurately collect equipment operating parameters and product quality data. The central monitoring platform uses an industrial touch screen with a clear and intuitive visual interface, supporting functions such as data query, curve analysis, and historical playback. The alarm module uses audible and visual alarms, and the alarm threshold can be customized according to production needs, with an alarm response time of ≤1 second.

[0073] It achieves comprehensive monitoring of system operation status with no blind spots, and the data acquisition is highly real-time and accurate. The central monitoring platform provides operators with a convenient operating interface, reducing the difficulty of operation. The alarm module can detect anomalies in a timely manner, buying time for anomaly handling, preventing the escalation of faults, and improving the operational safety of the system.

[0074] The optimization and scheduling unit is the optimization and decision-making center of the system. It mainly consists of a data storage module, an algorithm model module, and a report generation module. Its core functions are to analyze operating data, generate optimization strategies, and output optimization reports.

[0075] The data storage module uses a large-capacity hard drive, which can store more than one year of operating data and supports fast data query and export. The algorithm model module has built-in machine learning models and PID control algorithms, which can generate optimized scheduling strategies based on real-time and historical data. The report generation module can automatically generate optimization reports, including parameter comparisons before and after optimization, effect analysis, and suggested measures. It supports printing and exporting reports.

[0076] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for separating and purifying methylamine, characterized in that, Includes the following steps: S1: Obtain crude methylamine raw material from methanol and ammonia catalytic synthesis and collect data, followed by impurity removal and preheating treatment; S2: Encrypt and transmit the data collected in step 1 to the control terminal; S3: The control terminal calculates core parameters based on the transmitted data and adjusts the operating parameters of the deammoniation tower and extraction tower to achieve the separation of ammonia-trimethylamine azeotrope and the extraction of trimethylamine; S4: The control terminal command optimizes the dehydration tower to selectively extract impurities and simultaneously controls the operation of the extraction water flash evaporation system to regenerate and circulate the extraction water; S5: Pass the mixed gas from the top of the dehydration tower into the separation tower, and adjust the separation tower parameters to achieve the staged extraction of monomethylamine and dimethylamine; S6: Pass the residual liquid from the separation tower into the methanol recovery tower to recover methanol and circulate it, while simultaneously treating various waste liquids and flash gases; S7: Real-time monitoring of unit parameters and performance indicators, calculation of system operating cycle and failure probability; S8: Optimize scheduling by proposing adjustment strategies based on monitoring data and dynamically optimizing the operating parameters of each stage.

2. The method for separating and purifying methylamine according to claim 1, characterized in that: The data acquisition in step 1 specifically involves collecting compositional data of monomethylamine, dimethylamine, trimethylamine, ammonia, methanol, water, and heavy component impurities in the crude methylamine raw material, as well as raw material temperature data.

3. The method for separating and purifying methylamine according to claim 1, characterized in that: The encrypted transmission in step 2 specifically involves transmitting the raw material composition data, raw material temperature data, and pretreatment process parameters collected in step 1 to the control terminal via a self-access communication protocol. Encryption technology is used during the transmission process to prevent data leakage and tampering.

4. The method for separating and purifying methylamine according to claim 1, characterized in that: The core parameters of step 3 are the deammoniation efficiency and the extraction selectivity coefficient. The specific adjustment of the operating parameters includes adjusting the reflux ratio and bottom temperature of the deammoniation tower, as well as the extraction water flow rate and feed rate of the extraction tower. Specifically, the separation and extraction involve distilling the ammonia-trimethylamine azeotrope from the top of the deammoniation tower and returning it to the synthesis section, while extracting trimethylamine from the top of the extraction tower.

5. The method for separating and purifying methylamine according to claim 1, characterized in that: The targeted impurity removal in step 4 specifically involves the control terminal instructing the optimized dehydration tower to selectively extract heavy component impurities from the impurity enrichment area based on the impurity enrichment status within the tower. The extraction water regeneration specifically involves controlling the extraction water flash evaporation system to operate under preset pressure and temperature conditions, so that the material maintains a suitable residence time to break the hydrogen bond association system between trace organic impurities and water molecules in the extraction water. After removing trace organic impurities, the extraction water is cooled to a temperature that meets the process requirements and returned to the extraction tower for recycling.

6. The method for separating and purifying methylamine according to claim 1, characterized in that: The fine separation of methylamine in step 5 specifically involves introducing a monomethylamine-dimethylamine mixture from the top of the optimized dehydration tower into the separation tower, adjusting the separation tower to a suitable operating pressure and reflux ratio at the control end, collecting monomethylamine from the top of the tower, and collecting dimethylamine from the side line position corresponding to the theoretical plate of the tower body.

7. The method for separating and purifying methylamine according to claim 1, characterized in that: The methanol recovery in step 6 specifically involves feeding the residue from the bottom of the separation tower into a methanol recovery tower, controlling the tower to the corresponding operating pressure and reflux ratio, recovering the methanol therein, and recycling it to the synthesis section. The wastewater treatment specifically involves introducing the side-stream extract from the optimized dehydration tower, a portion of the bottom liquid, and the flash gas from the extraction water flash evaporation system into the wastewater treatment unit, and controlling the washing liquid to an appropriate circulation ratio.

8. The method for separating and purifying methylamine according to claim 1, characterized in that: The real-time monitoring in step 7 specifically involves monitoring the operating parameters of each tower, product purity, impurity removal rate, and hydrogen bond dissociation rate, and calculating the continuous operating cycle of the system and the probability of equipment failure.

9. The method for separating and purifying methylamine according to claim 1, characterized in that: The optimization scheduling in step 8 specifically involves proposing adjustment strategies for product purity stability and system energy consumption based on the system operation data from step 7, and dynamically optimizing the operating parameters of each stage, such as deammoniation, extraction, separation, and recovery.

10. A methylamine separation and purification system, characterized in that, The purification method according to any one of claims 1-9 includes a raw material pretreatment unit, a data acquisition and transmission unit, a separation tower unit, an auxiliary processing unit, and a control and monitoring unit; The raw material pretreatment unit includes a precision filter and a plate heat exchanger, used to remove solid impurities from the raw material and preheat it; The data acquisition and transmission unit includes a concentration sensor, a temperature sensor, and a data transmission module, used to acquire raw material data and process parameters and transmit them in encrypted form; The separation tower unit includes a deammoniation tower, an extraction tower, an optimized dehydration tower, a separation tower, and a methanol recovery tower, used to achieve graded separation and resource recovery of methylamine; The auxiliary processing unit includes an extraction water flash evaporation system and a wastewater treatment unit, used to purify the circulating extraction water and treat wastewater. The control and monitoring unit includes a control module, a monitoring and management module, and an optimization and scheduling module, which are used to receive data, calculate parameters, issue control commands, monitor operating status, and optimize scheduling.

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