Carbon dioxide recycling pipeline system for propylene carbonate production process

Abstract

The invention belongs to the technical field of propylene carbonate production management and control, and particularly relates to a carbon dioxide recycling pipeline system for a propylene carbonate production process, which comprises a desorption gas pretreatment module, a desorption gas purification module, a pipeline partial pressure flow coordinated regulation and control module, a circulating reuse adaptation module and a recycling efficiency real-time monitoring module, tail gas water vapor and impurities are removed through the desorbed gas pretreatment module, parameters are calibrated, deep purification is achieved through automatic switching regeneration of the two sets of parallel two-stage adsorption towers, partial pressure stability control and flow fluctuation control are conducted on carbon dioxide, the circulating reuse adaptation module supplies materials to a reaction kettle according to needs, redundant gas is stored after being filtered out, and the tail gas is purified. And when the recovery efficiency is lower than a threshold value, automatic early warning and regulation are carried out, efficient recovery and accurate reuse of carbon dioxide are facilitated, the purity and suitability of recovered gas are guaranteed, and the resource utilization rate of propylene carbonate production is increased.

Description

Technical Field

[0001] This invention relates to the field of propylene carbonate production control technology, specifically to a carbon dioxide recovery and utilization pipeline system in the propylene carbonate production process. Background Technology

[0002] Propylene carbonate, as an important chemical raw material, is widely used in gas separation, electrolytes, organic synthesis and other fields. Carbon dioxide is the core raw material in its synthesis reaction. In the production process of propylene carbonate, the exhaust gas discharged from the reactor contains a large amount of unreacted carbon dioxide. Direct emission of this gas not only wastes resources but also puts pressure on the environment. Therefore, the design and optimization of pipeline systems for carbon dioxide recovery and utilization has become an important research direction in the production process of propylene carbonate.

[0003] Currently, this type of exhaust gas is typically treated using methods such as single-stage adsorption, simple condensation, or filter filtration, attempting to recover carbon dioxide and reuse it in the reaction system to achieve resource recovery and emission reduction goals. Some solutions also use simple pressure or flow regulation devices to try to adapt the recovered gas to the reaction requirements. However, existing recovery and utilization solutions have significant technical shortcomings: Firstly, the purification process design is crude, mostly using single-stage adsorption or single filtration, which makes it difficult to deeply remove trace organic impurities and fine particles from the exhaust gas. This results in the purity of the recovered carbon dioxide failing to meet the high standards required for the synthesis reaction, thus affecting the product quality. Furthermore, there is a lack of a coordinated control mechanism for partial pressure and flow rate. Adjusting only one parameter can easily lead to problems such as partial pressure deviating from the optimal reaction range or excessive flow rate fluctuations, making it impossible to accurately adapt to the dynamic requirements of the propylene carbonate synthesis reaction. Secondly, the storage of excess recovered gas lacks effective online impurity filtration and closed-loop purity control. Impurities are prone to accumulate, and substandard gases cannot be recycled in a timely manner, affecting the safety and stability of subsequent reuse. Furthermore, most adsorption devices are single-tower designs or have inaccurate switching logic, which can easily lead to interruptions in the purification process due to the adsorbent saturation and failure to regenerate in time. At the same time, there is a lack of real-time monitoring and abnormal early warning mechanisms for the overall recovery efficiency, resulting in significant resource waste and making it difficult to guarantee the continuous stability of the recovery process.

[0004] Therefore, developing a carbon dioxide recovery and utilization pipeline system for propylene carbonate production processes that can achieve efficient carbon dioxide recovery, deep purification, coordinated and stable control of partial pressure and flow, precise reuse, and real-time monitoring throughout the entire process, while ensuring the purity and storage safety of the recovered gas and improving the continuous stability of the recovery process, has become an urgent technical problem to be solved in the field of propylene carbonate production management. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon dioxide recovery and utilization pipeline system for the production process of propylene carbonate, so as to achieve efficient recovery, deep purification, precise reuse and full process control of carbon dioxide, and significantly improve the resource utilization rate and reaction stability of propylene carbonate production.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a carbon dioxide recovery and utilization pipeline system for propylene carbonate production process, including a desorbed gas pretreatment module, a desorbed gas purification module, a pipeline partial pressure and flow rate coordinated control module, a recycling and reuse adaptation module, and a real-time monitoring module for recovery efficiency; The desorption gas pretreatment module pretreats the desorption tail gas discharged from the propylene carbonate reactor to remove water vapor, large particulate impurities and trace reaction by-products from the tail gas, while collecting and calibrating the core parameters of the desorption gas. The desorption gas purification module deeply purifies the pretreated desorption gas through an adsorption tower to adsorb and remove organic impurities from the desorption gas, and obtains high-purity carbon dioxide for output. The pipeline partial pressure and flow rate coordinated control module integrates precise control of carbon dioxide partial pressure with stable pipeline flow control, ensuring that the partial pressure and flow rate of recovered carbon dioxide are simultaneously and stably adapted to the requirements of the propylene carbonate synthesis reaction. The recycling and reuse adaptation module accurately calculates and matches the flow rate of recovered carbon dioxide, directly reusing the recovered carbon dioxide to the propylene carbonate synthesis reaction, and directing excess carbon dioxide gas to a storage tank for later use. The real-time recovery efficiency monitoring module uses carbon dioxide recovery efficiency decision analysis to determine whether any abnormal recovery efficiency signals are generated.

[0007] Furthermore, the exhaust gas discharged from the propylene carbonate reactor enters the exhaust gas pretreatment module. The exhaust gas pretreatment module condenses the water vapor in the exhaust gas into liquid water through a low-temperature condensation unit and discharges it through a drain valve. The exhaust gas also passes through a high-precision filter screen to remove large particulate solid impurities. The desorbed gas pretreatment module collects parameters of the pretreated exhaust gas through the parameter acquisition unit. Based on the temperature sensor, humidity sensor, flow sensor and gas chromatograph, it collects the temperature T, humidity H, initial volumetric flow rate Qo and initial carbon dioxide concentration Co of the exhaust gas respectively. The collected parameters are calibrated by the data calibration unit and then transmitted to the desorption gas purification module and the real-time recovery efficiency monitoring module. The pre-treated desorption gas is then transported to the desorption gas purification module through pipelines.

[0008] Furthermore, the desorbed gas purification module is equipped with two sets of parallel adsorption towers. During the adsorption process, the saturation level is precisely determined to automatically switch between adsorption towers. The specific process of determining the saturation level is as follows: The saturated adsorption capacity per unit mass of adsorbent, qm, and the adsorbent loading mass per single tower, mads, are obtained. The total saturated adsorption capacity per single tower, qtotal, is calculated using the formula qtotal = qm × mads. The adsorption tower in the adsorption state is monitored to obtain the current average concentration of impurities at the inlet of the adsorption tower, Cin, the average volumetric flow rate of the inlet gas, Q, and the continuous operating time t of the current cycle. The cumulative adsorption impurity mass mads(t) after operating time t is calculated by the real-time cumulative adsorption impurity mass calculation formula. When mads(t) ≥ 0.8 × qtotal, the current adsorption tower is automatically switched to vacuum pressure swing desorption and regeneration state, with a desorption pressure of 5 to 8 kPa, and the standby tower is activated to continue adsorption.

[0009] Furthermore, both adsorption towers perform adsorption operations through two-stage adsorption coupling. The first-stage adsorption unit uses zeolite adsorbent, and the second-stage adsorption unit uses Mg-MOF-74 adsorbent. The first-stage adsorption unit and the second-stage adsorption unit perform the same saturation judgment and switching logic.

[0010] Furthermore, the pipeline partial pressure and flow rate coordinated control module collects the total pipeline pressure Ptotal through a pressure sensor and the carbon dioxide mole fraction XCO2 through a gas chromatograph. The actual partial pressure of carbon dioxide, PCO2, is calculated based on the formula for calculating the partial pressure of carbon dioxide. The calculated partial pressure PCO2 is then compared with the optimal partial pressure range for the reaction, which is 0.3–0.5 MPa. Simultaneously, the total pressure and flow rate are adjusted in a coordinated manner. The adjusted carbon dioxide gas enters the recycling and reuse adaptation module, and the relevant monitoring data of the adjustment are transmitted to the recycling and reuse adaptation module and the real-time monitoring module for recovery efficiency.

[0011] Furthermore, the specific strategies for coordinating and regulating total pressure and flow are as follows: If PCO2 > 0.5MPa: Simultaneously open the pipeline pressure reducing valve to lower the total pressure, and adjust the flow regulating valve to reduce the partial pressure and flow rate to return to the target range at the same time; If PCO2 < 0.3MPa: Simultaneously start the booster pump to increase the total pressure, and adjust the flow regulating valve to ensure that the partial pressure and flow rate reach the standard simultaneously; If the partial pressure is within acceptable limits but the flow rate deviates from the flow rate requirement of the propylene carbonate reactor: stabilize the flow rate directly through a flow buffer tank and a flow regulating valve to control the flow rate fluctuation within ±5%.

[0012] Furthermore, the pipeline pressure and flow rate coordination control module delivers the stabilized carbon dioxide to the recycling and reuse adapter module. The recycling and reuse adapter module receives the stabilized flow rate data Qstable and simultaneously collects the propylene oxide concentration CPO in the reactor through a liquid chromatograph. Based on a reaction molar ratio of 1:1 and ideal gas conditions, the theoretical CO2 flow rate PCO2 required for the propylene carbonate reactor was calculated using a carbon dioxide flow rate adaptation formula. After calculating the theoretical inlet flow rate QCO2, the recovered carbon dioxide is divided into two paths: one path is directly fed into the propylene carbonate reactor according to the theoretical inlet flow rate QCO2 to participate in the synthesis; the other path is the excess carbon dioxide gas, which is output and stored according to the excess gas flow rate Qsurplus, and the excess gas flow rate Qsurplus = Qstable - QCO2.

[0013] Furthermore, the specific analysis process for carbon dioxide recovery efficiency decision analysis is as follows: Based on the ratio of effective carbon dioxide recovery to total input, the carbon dioxide recovery efficiency η is calculated. The recovery efficiency threshold is set at 95%. When the carbon dioxide recovery efficiency η is lower than 95%, an abnormal recovery efficiency signal is generated, the abnormal link is automatically located and control instructions are issued, and the data is uploaded to the production control system.

[0014] Furthermore, the recycle adapter module is connected to the pipeline impurity online filtration module. The pipeline impurity online filtration module removes excess carbon dioxide output from the recycle adapter module online to remove trace impurities. Solid particles are filtered out through 1μm and 0.1μm filter screens, and then organic impurities are deeply removed through an activated carbon layer.

[0015] Furthermore, the pipeline impurity online filtration module uses an online purity detector to detect the carbon dioxide purity Ce in real time. If Ce ≥ 99.5%, the carbon dioxide is introduced into the storage tank for later use; if Ce < 99.5%, the carbon dioxide is returned to the desorption gas purification module for repurification.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the desorbed gas pretreatment module effectively removes water vapor and impurities from the tail gas and accurately calibrates parameters. The purification design of the two-stage parallel adsorption tower achieves continuous deep purification of the desorbed gas. It also accurately and stably controls the partial pressure and flow rate of carbon dioxide to meet the reaction requirements, and dynamically matches the feed flow rate according to the reactor conditions. Combined with real-time monitoring and abnormal control of recovery efficiency, it achieves efficient recovery and precise reuse of carbon dioxide, significantly improving the resource utilization rate and process stability of propylene carbonate production.

[0017] 2. In this invention, the online impurity filtration module in the pipeline enables the online graded filtration of solid particles and deep removal of organic impurities from excess carbon dioxide, preventing the accumulation of impurities in the storage tank, ensuring the purity of the stored carbon dioxide, providing high-quality raw material gas for subsequent reuse, and the gas that does not meet the purity standard is returned for repurification, further improving the overall gas recovery and utilization rate and reducing raw material waste. Attached Figure Description

[0018] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings; Figure 1 This is an overall system block diagram of the present invention; Figure 2 This is a flowchart illustrating the overall workflow of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: As Figure 1-2 As shown, the carbon dioxide recovery and utilization pipeline system proposed in the propylene carbonate production process of this invention includes a desorbed gas pretreatment module, a desorbed gas purification module, a pipeline partial pressure and flow coordinated control module, a recycling and reuse adaptation module, and a real-time monitoring module for recovery efficiency. The desorption gas pretreatment module pretreats the desorption tail gas discharged from the propylene carbonate reactor, removing water vapor, large particulate impurities and trace amounts of reaction byproducts from the tail gas. At the same time, it collects and calibrates the core parameters of the desorption gas, providing standardized and highly reliable raw material gas and parameter data for the precise operation of subsequent modules, and avoiding the impact of impurities and parameter deviations on the subsequent purification and control effects. Specifically, the exhaust gas from the propylene carbonate reactor (mainly composed of carbon dioxide, propylene, methanol, water vapor and a small amount of solid impurities) enters the exhaust gas pretreatment module. The exhaust gas pretreatment module first condenses the water vapor in the exhaust gas into liquid water through a low-temperature condensation unit (condensation temperature controlled at 15-20℃) and discharges it through a drain valve to prevent water vapor from entering the subsequent adsorption unit and causing the adsorbent to fail. Subsequently, the exhaust gas passes through a high-precision filter (with a pore size of 10μm) to remove large solid impurities (such as catalyst particles that have fallen off the reactor) from the exhaust gas, preventing impurities from damaging the pipelines and the core components of subsequent modules. Furthermore, the desorption gas pretreatment module collects parameters of the pretreated exhaust gas through the parameter acquisition unit. Based on the temperature sensor, humidity sensor, flow sensor and gas chromatograph, it collects the exhaust gas temperature T, humidity H, initial volumetric flow rate Qo and initial carbon dioxide concentration Co respectively. The collected parameters are calibrated by the data calibration unit (using an error correction algorithm, with a correction error ≤ ±2%) and then transmitted to the desorption gas purification module and the real-time recovery efficiency monitoring module. The pre-treated desorption gas is then transported to the desorption gas purification module through pipelines.

[0021] The desorbed gas purification module uses an adsorption tower to deeply purify the pretreated desorbed gas, adsorbing and removing organic impurities such as propylene and methanol from the desorbed gas to obtain high-purity carbon dioxide for output. At the same time, it realizes online regeneration of the adsorbent, ensuring the continuous and stable purification process and providing qualified raw material gas for subsequent partial pressure and flow rate coordinated control. Specifically, the desorbed gas purification module is equipped with two sets of parallel adsorption towers. During the adsorption process, the adsorption tower is automatically switched based on precise saturation level determination. The precise saturation level determination process is as follows: Obtain the saturated adsorption capacity qm per unit mass of adsorbent (determined by standard adsorption experiments) and the adsorbent loading mass mads per tower (fixed equipment parameter). Calculate the total saturated adsorption capacity qtotal of the adsorbent per tower using the formula qtotal=qm×mads. In addition, the adsorption tower in the adsorption state is monitored to obtain the current average inlet impurity concentration Cin (unit: mg / m³). 3 ), average inlet gas volumetric flow rate Q (unit: m³) 3 The cumulative adsorbed impurity mass mads(t) after running for t time is calculated using the real-time cumulative adsorbed impurity mass calculation formula, given by the continuous running time t (in hours) and the adsorbed impurity mass / h. ; Among them, 10 6 Unit conversion factor, converting mg to kg; When mads(t) ≥ 0.8 × qtotal, the current adsorption tower is in a saturated state. At this time, the current adsorption tower is automatically switched to vacuum pressure swing desorption and regeneration state with a desorption pressure of 5 to 8 kPa, and the standby tower is activated to continue adsorption.

[0022] Preferably, both adsorption towers perform adsorption operations through two-stage adsorption coupling. The first-stage adsorption unit uses 13X zeolite adsorbent (modified to enhance the adsorption capacity for propylene and methanol) to selectively adsorb organic impurities such as propylene and methanol in the desorption gas under normal temperature (25-30℃) and normal pressure (0.1MPa) conditions. The second-stage adsorption unit uses Mg-MOF-74 adsorbent to deeply adsorb the trace impurities remaining after the first-stage adsorption, further reducing the impurity content and helping to ensure that the purity of carbon dioxide after purification reaches more than 99.5%. Furthermore, the first-stage adsorption unit and the second-stage adsorption unit perform the same saturation judgment and switching logic, that is, they both adopt the above-mentioned precise saturation amount decision analysis method, and switch to the standby tower when there is an adsorption unit in the adsorption tower that is in a saturated state.

[0023] The pipeline partial pressure and flow rate coordinated control module integrates precise control of carbon dioxide partial pressure with stable control of pipeline flow rate, so that the partial pressure and flow rate of recovered carbon dioxide can be stably adapted to the needs of propylene carbonate synthesis reaction, ensuring pipeline transportation safety and reaction matching degree. Specifically, the pipeline partial pressure and flow coordinated control module collects the total pipeline pressure Ptotal through a pressure sensor and collects the carbon dioxide mole fraction XCO2 through a gas chromatograph. Based on the formula for calculating carbon dioxide partial pressure The actual partial pressure of carbon dioxide, PCO2, is calculated and compared with the optimal partial pressure range for the reaction, which is 0.3–0.5 MPa. Simultaneously, the total pressure and flow rate are adjusted, and the adjusted carbon dioxide gas enters the recycling and reuse adaptation module. The relevant monitoring data of the adjustment is transmitted to the recycling and reuse adaptation module and the real-time monitoring module for recovery efficiency.

[0024] Furthermore, the specific strategies for coordinating the regulation of total pressure and flow are as follows: If PCO2 > 0.5MPa: Simultaneously open the pipeline pressure reducing valve to lower the total pressure, and adjust the flow regulating valve to reduce the partial pressure and flow rate to return to the target range at the same time; If PCO2 < 0.3MPa: Simultaneously start the booster pump to increase the total pressure, and adjust the flow regulating valve to ensure that the partial pressure and flow rate reach the standard simultaneously; If the partial pressure is within acceptable limits but the flow rate deviates from the flow rate requirement of the propylene carbonate reactor: stabilize the flow rate directly through a flow buffer tank and a flow regulating valve to control the flow rate fluctuation within ±5%.

[0025] It should be noted that the partial pressure and flow rate are calculated and executed synchronously throughout the entire adjustment process, without any independent adjustment overlap or lag. The adjusted carbon dioxide gas is then delivered to the recycling and reuse adaptation module. Furthermore, the monitored data, such as stable partial pressure (PCO2) and stable flow rate (Qstable), are also transmitted to the recycling and reuse adaptation module and the real-time recovery efficiency monitoring module.

[0026] The recycling and adaptation module accurately calculates and matches the flow rate of recovered carbon dioxide based on the real-time concentration of propylene oxide in the propylene carbonate reactor, combined with the reaction molar ratio and gas state. The recovered carbon dioxide is directly reused in the propylene carbonate synthesis reaction, and excess carbon dioxide gas is directed to a storage tank for later use, thereby maximizing the utilization of recovered CO2. Specifically, the pipeline pressure and flow rate coordinated control module delivers the stabilized carbon dioxide to the recycling and reuse adapter module. The recycling and reuse adapter module receives the stabilized flow rate data Qstable and simultaneously collects the propylene oxide concentration CPO in the reactor through a liquid chromatograph. Based on a reaction molar ratio of 1:1 (i.e., the molar ratio of propylene oxide to CO2 in the propylene carbonate synthesis reaction is 1:1) and ideal gas conditions, the theoretical CO2 inlet flow rate PCO2 required for the propylene carbonate reactor is calculated using the appropriate CO2 inlet flow rate formula. The CO2 inlet flow rate formula is shown below: ; Wherein, CPO: propylene oxide concentration in the reactor, meaning the amount of PO substance contained in each liter of the reaction system. Acquisition method: Data is collected using liquid chromatography (measurement accuracy ±0.01 mol / L), with the collection point at the middle of the reactor to ensure the representativeness of the concentration data. Vreactor: Effective volume of the reactor (m³) 3 The production equipment is designed with fixed parameters, so real-time data collection is not required. Vm: Molar volume of gas, taken as 0.0224 m³ at room temperature and pressure. 3 / mol (molar volume of an ideal gas under standard conditions, suitable for routine industrial operating conditions). 1000: Unit conversion factor, meaning to convert the unit of reaction vessel volume from (m³) to (m³). 3 Convert to liters (L); After calculating the theoretical inlet flow rate QCO2, the recovered carbon dioxide is divided into two paths: one path is directly fed into the propylene carbonate reactor according to the theoretical inlet flow rate QCO2 to participate in the synthesis; the other path is the excess carbon dioxide gas, which is output and stored according to the excess gas flow rate Qsurplus, and the excess gas flow rate Qsurplus = Qstable - QCO2.

[0027] The real-time recovery efficiency monitoring module monitors all modules in the system and uses carbon dioxide recovery efficiency decision analysis to determine whether any abnormal recovery efficiency signals are generated. Specifically, the analysis process of carbon dioxide recovery efficiency decision analysis is as follows: Based on the ratio of effective carbon dioxide recovery to total input, the carbon dioxide recovery efficiency η is calculated. The recovery efficiency threshold is set at 95%. When the carbon dioxide recovery efficiency η is lower than 95%, an abnormal recovery efficiency signal is generated, the abnormal link is automatically located and control instructions are issued, and the data is uploaded to the production control system.

[0028] Example 2: Based on the technology of Example 1, the existing propylene carbonate production process lacks effective online trace impurity filtration methods for the recovered excess carbon dioxide gas before storage. Adsorbent particles and trace organic impurities are easily left in the gas, and long-term storage will cause impurity accumulation, affecting the purity of carbon dioxide for subsequent reuse. At the same time, the purity of carbon dioxide is not tested in real time before storage. If the purity of the purified gas does not meet the standard but is stored directly, the overall quality of the stored gas will be reduced, which will not meet the raw material purity requirements of the propylene carbonate synthesis reaction, thereby affecting the reaction effect and product quality.

[0029] To address the aforementioned issues, this embodiment is based on Embodiment 1 and further optimizes the content of Embodiment 1. The difference from Embodiment 1 is that, in this embodiment, the recycling adapter module is connected to the pipeline impurity online filtration module. The pipeline impurity online filtration module performs online trace impurity filtration on excess carbon dioxide output from the recycling adapter module (first filtering solid particles through a 1μm filter and then a 0.1μm filter, followed by deep removal of organic impurities through an activated carbon layer), removing residual adsorbent particles and trace organic impurities, ensuring the purity of the stored gas, avoiding impurity accumulation that could affect reuse, and simultaneously achieving centralized collection and treatment of impurities.

[0030] Furthermore, the online impurity filtration module in the pipeline uses an online purity detector to monitor the carbon dioxide purity (Ce) in real time. If Ce ≥ 99.5%, the carbon dioxide is introduced into a storage tank for later use, solving the problem of no purity detection in the stored gas and direct storage of substandard gas in the existing technology. This avoids the impact of low-purity gas on the synthesis reaction effect and product quality of propylene carbonate. If Ce < 99.5%, the carbon dioxide is returned to the desorption gas purification module for repurification, further improving the overall gas recovery and utilization rate and reducing raw material waste.

[0031] The working principle of this invention is as follows: During use, the exhaust gas discharged from the propylene carbonate reactor enters the exhaust gas pretreatment module. After low-temperature condensation and dehydration, and removal of large particulate impurities by a high-precision filter, the core parameters are collected and calibrated by the parameter acquisition unit. The exhaust gas purification module uses two sets of parallel two-stage adsorption towers to achieve automatic switching and vacuum pressure swing regeneration based on precise saturation. This continuously and deeply removes organic impurities and outputs high-purity carbon dioxide. The high-purity carbon dioxide enters the pipeline partial pressure and flow rate coordinated control module. After partial pressure calculation and linkage adjustment of total pressure and flow rate, it is stably output. The recycling and reuse adaptation module accurately calculates the theoretical CO2 flow rate and delivers the carbon dioxide in two paths. When the recovery efficiency is lower than the threshold, an abnormal signal is generated. This achieves efficient recovery and precise reuse of carbon dioxide in propylene carbonate production, ensuring the adaptability of the recovered gas to the synthesis reaction and significantly improving the utilization rate of production resources.

[0032] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, enabling those skilled in the art to better understand and utilize it. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A carbon dioxide recovery and utilization pipeline system for propylene carbonate production processes, characterized in that, It includes a desorbed gas pretreatment module, a desorbed gas purification module, a pipeline partial pressure and flow coordinated control module, a circulation reuse adaptation module, and a recovery efficiency real-time monitoring module; The desorption gas pretreatment module pretreats the desorption tail gas discharged from the propylene carbonate reactor, and at the same time collects and calibrates the core parameters of the desorption gas. The desorbed gas purification module uses an adsorption tower to deeply purify the pretreated desorbed gas, obtaining high-purity carbon dioxide and outputting it. The pipeline partial pressure and flow rate coordinated control module ensures that the partial pressure and flow rate of recovered carbon dioxide are simultaneously and stably adapted to the requirements of the propylene carbonate synthesis reaction. The recycling and reuse adaptation module accurately calculates and matches the flow rate of recovered carbon dioxide, directly reusing the recovered carbon dioxide to the propylene carbonate synthesis reaction, and directing excess carbon dioxide gas to a storage tank for later use. The real-time recovery efficiency monitoring module uses carbon dioxide recovery efficiency decision analysis to determine whether an abnormal recovery efficiency signal is generated.

2. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 1, characterized in that, The desorbed gas pretreatment module condenses the water vapor in the exhaust gas into liquid water through a low-temperature condensation unit and discharges it through a drain valve. The exhaust gas also passes through a high-precision filter to remove large particulate solid impurities. The desorbed gas pretreatment module collects parameters of the pretreated exhaust gas through the parameter acquisition unit. The collected parameters are calibrated by the data calibration unit and then transmitted to the desorbed gas purification module and the real-time recovery efficiency monitoring module. The pretreated desorbed gas is then transported to the desorbed gas purification module through pipelines.

3. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 1, characterized in that, The desorbed gas purification module is equipped with two sets of parallel adsorption towers. During the adsorption process, the saturation level is precisely determined to automatically switch between adsorption towers. The specific process of precise saturation level determination is as follows: The saturated adsorption capacity per unit mass of adsorbent, qm, and the adsorbent loading mass per single tower, mads, are obtained. The total saturated adsorption capacity per single tower, qtotal, is calculated using the formula qtotal = qm × mads. The cumulative adsorbed impurity mass mads(t) after running time t is calculated by the real-time cumulative adsorption impurity mass calculation formula; when mads(t)≥0.8×qtotal, the current adsorption tower is automatically switched to vacuum pressure swing desorption and regeneration state, and the standby tower is activated to continue adsorption.

4. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 3, characterized in that, Both adsorption towers perform adsorption operations through two-stage adsorption coupling. The first-stage adsorption unit uses zeolite adsorbent, and the second-stage adsorption unit uses Mg-MOF-74 adsorbent. The first-stage adsorption unit and the second-stage adsorption unit perform the same saturation judgment and switching logic.

5. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 1, characterized in that, The pipeline partial pressure and flow coordinated control module collects the total pipeline pressure Ptotal through a pressure sensor and collects the carbon dioxide mole fraction XCO2 through a gas chromatograph. The actual partial pressure of carbon dioxide, PCO2, is calculated based on the formula for calculating the partial pressure of carbon dioxide. The calculated partial pressure PCO2 is then compared with the optimal partial pressure range for the reaction, which is 0.3–0.5 MPa. The total pressure and flow rate are adjusted in conjunction with these adjustments.

6. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 5, characterized in that, The specific strategies for coordinating and regulating total pressure and flow are as follows: If PCO2 > 0.5 MPa: Simultaneously open the pipeline pressure reducing valve to lower the total pressure and adjust the flow regulating valve to reduce the partial pressure and flow rate to fall back to the target range at the same time; If PCO2 < 0.3 MPa: Simultaneously start the booster pump to increase the total pressure and adjust the flow regulating valve to increase the partial pressure and flow rate to meet the standard at the same time; If the partial pressure is qualified but the flow rate deviates from the flow rate requirement of the propylene carbonate reactor: directly stabilize the flow rate through the flow buffer tank and flow regulating valve to control the flow rate fluctuation within ±5%.

7. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 1, characterized in that, The pipeline pressure and flow rate coordination control module delivers the stabilized carbon dioxide to the recycling and reuse adaptation module. The recycling and reuse adaptation module calculates the theoretical CO2 inflow rate PCO2 required for the propylene carbonate reactor using the carbon dioxide inflow rate adaptation formula. After calculating the theoretical inflow rate QCO2, one path directly feeds the carbon dioxide into the propylene carbonate reactor for synthesis according to the theoretical inflow rate QCO2, while the other path outputs and stores the excess carbon dioxide gas.

8. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 7, characterized in that, The specific analysis process for carbon dioxide recovery efficiency decision analysis is as follows: Based on the ratio of effective carbon dioxide recovery to total input, the carbon dioxide recovery efficiency η is calculated. When the carbon dioxide recovery efficiency η is lower than 95%, an abnormal recovery efficiency signal is generated, the abnormal link is automatically located and control instructions are issued, and the data is uploaded to the production control system.

9. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 8, characterized in that, The reusable adapter module connects to the pipeline impurity online filtration module, which removes excess carbon dioxide and trace impurities online. Solid particles are removed through 1μm and 0.1μm filter screens, and then organic impurities are removed through an activated carbon layer.

10. The carbon dioxide recovery and utilization pipeline system for propylene carbonate production process according to claim 9, characterized in that, The pipeline impurity online filtration module detects the carbon dioxide purity Ce in real time using an online purity detector. If Ce ≥ 99.5%, the carbon dioxide is introduced into the storage tank for later use; if Ce < 99.5%, the carbon dioxide is returned to the desorption gas purification module for repurification.

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