A system and method for dry removal of carbon dioxide from an olefin feed gas, an olefin separation plant
By combining pretreatment, multi-stage adsorption towers, and automatic control, the problems of insufficient decarbonization accuracy and unstable operation in existing dry decarbonization processes have been solved, achieving efficient and continuous carbon dioxide removal and olefin recovery, and ensuring the stable operation and high automation of the olefin separation unit.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA BAOFENG COAL-BASED NEW MATERIAL CO LTD
- Filing Date
- 2026-04-20
- Publication Date
- 2026-06-05
AI Technical Summary
Existing dry decarbonization processes suffer from problems such as insufficient decarbonization precision, incomplete adsorbent regeneration, poor operational continuity, low automation, and poor adaptability to operating conditions during carbon dioxide removal from olefin feed gas, resulting in low olefin recovery rates and unstable production.
The system employs a pretreatment unit to remove free water and heavy hydrocarbon droplets, and uses a multi-stage series adsorption tower and a pressure swing regeneration unit for stepwise deep removal of carbon dioxide. An automatic control unit enables the adsorption towers to operate and regenerate in groups. By combining activated carbon-based, modified molecular sieves and alkaline composite solid adsorbents, high-precision decarbonization and continuous operation are achieved.
It achieves high-precision carbon dioxide removal, ensures the stable operation of the olefin separation unit, improves the olefin recovery rate, and ensures the continuity of the system and ease of operation and maintenance through fully automatic control.
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Figure CN122141405A_ABST
Abstract
Description
Technical Field
[0001] This application generally relates to the field of gas separation and purification technology. More specifically, this application relates to a dry carbon dioxide removal system and method for olefin feedstock gas, and an olefin separation device. Background Technology
[0002] Olefin feedstock gases (such as the ethylene and propylene mixture produced by an MTO unit) typically contain carbon dioxide impurities. If these impurities are not thoroughly removed, they can poison the catalyst in subsequent polymerization reactions, affecting the quality of polyolefin products. Therefore, it is necessary to perform carbon dioxide removal treatment on olefin feedstock gases.
[0003] In existing technologies, dry decarbonization processes typically employ pressure swing adsorption (PSA) or fixed-bed adsorption, using conventional adsorbents such as molecular sieves and activated carbon. These processes involve alternating operation of a single or dual tower to adsorb and remove carbon dioxide from olefin gas under pressure, followed by depressurization for adsorbent regeneration. However, existing dry decarbonization processes still suffer from the following shortcomings: insufficient decarbonization precision; poor selectivity of a single adsorbent for carbon dioxide, making deep removal difficult; incomplete adsorbent regeneration and poor operational continuity; conventional dual-tower processes are prone to pressure fluctuations and discontinuous decarbonization during switching, leading to excessive outlet carbon dioxide levels. Furthermore, insufficient adsorbent regeneration results in a rapid decline in adsorption efficiency after prolonged operation, necessitating frequent shutdowns for adsorbent replacement, impacting production continuity; significant loss of effective components; the adsorption process easily entrains and adsorbs some olefin components, leading to loss of effective products and reduced olefin recovery rates; and low automation and poor adaptability to operating conditions. Existing systems largely rely on manual operation for tower switching and regeneration control, making it difficult to respond in real-time to fluctuations in feed load and changes in impurity content in the feed gas, thus failing to achieve fully automated and stable operation.
[0004] In view of this, there is an urgent need to provide a dry carbon dioxide removal system and method for olefin feedstock gas, as well as an olefin separation device scheme, so as to achieve high decarbonization accuracy, continuous and stable operation and high degree of automation at the same time. Summary of the Invention
[0005] In order to at least solve one or more of the technical problems mentioned above, this application proposes a dry carbon dioxide removal system and method for olefin feedstock gas, and an olefin separation device scheme in several aspects.
[0006] In a first aspect, this application provides a dry carbon dioxide removal system for olefin feed gas, comprising: a pretreatment unit for removing free water and heavy hydrocarbon droplets entrained in the olefin-containing feed gas; an adsorption unit comprising at least two adsorption towers connected in series, wherein each adsorption tower is filled with a composite adsorbent for adsorbing carbon dioxide; a pressure swing regeneration unit connected to each adsorption tower of the adsorption unit for controlling the adsorption towers to perform adsorption and regeneration alternately in groups; and an automatic control unit communicatively connected to the pretreatment unit, the adsorption unit, and the pressure swing regeneration unit, and for monitoring the feed parameters of the pretreatment unit in real time and automatically controlling the switching of the adsorption towers and the regeneration conditions.
[0007] In some embodiments, the adsorption unit includes a first adsorption tower, a second adsorption tower, and a third adsorption tower connected in series; wherein the first adsorption tower is filled with an activated carbon-based adsorbent, the second adsorption tower is filled with a modified molecular sieve adsorbent, and the third adsorption tower is filled with an alkaline composite solid adsorbent.
[0008] In some embodiments, the pretreatment unit includes a gas-liquid separator connected in series with an olefin-containing feed gas pipeline.
[0009] In some embodiments, the pressure swing regeneration unit includes a forward discharge pipeline, a reverse discharge pipeline, a vacuum pumping pipeline, and a flushing and regeneration pipeline connected to each adsorption tower, and a vacuum pump connected to the vacuum pumping pipeline. The pressure swing regeneration unit is used to perform forward discharge depressurization, reverse discharge depressurization, vacuum desorption, and flushing and regeneration operations on each adsorption tower in sequence.
[0010] In some embodiments, the forward discharge pipeline, reverse discharge pipeline, vacuum pipeline, and flushing and regeneration pipeline each include branches connected to each adsorption tower and a main pipe that connects the branches. Each branch is equipped with a control valve. The main pipe of the forward discharge pipeline is connected to the forward discharge buffer tank or the venting pipeline. The main pipe of the reverse discharge pipeline is connected to the venting or recovery system. The main pipe of the vacuum pipeline is connected to the vacuum pump. The main pipe of the flushing and regeneration pipeline is connected to the flushing gas source.
[0011] In some embodiments, the system further includes an interlocking bypass unit, which includes an emergency bypass pipe connected between the feed main pipe and the discharge main pipe, an emergency bypass valve disposed on the emergency bypass pipe, and branch shut-off valves disposed on the inlet pipe and outlet pipe of each adsorption tower stage, respectively.
[0012] In a second aspect, this application provides an olefin separation apparatus, including an olefin separation main unit, characterized in that it further includes the aforementioned dry carbon dioxide removal system for olefin feed gas, wherein the inlet of the dry carbon dioxide removal system is connected to an olefin-containing feed gas pipeline, and its outlet is connected to the feed inlet of the olefin separation main unit.
[0013] In a third aspect, this application provides a method for removing carbon dioxide using the aforementioned dry carbon dioxide removal system for olefin feed gas, characterized by comprising the following steps: a pretreatment step: introducing olefin-containing feed gas into a pretreatment unit to remove free water and heavy hydrocarbon droplets; a multi-stage adsorption step: allowing the pretreated gas to flow into the adsorption unit for stepwise removal of carbon dioxide; a pressure swing regeneration step: controlling the adsorption towers of the adsorption unit to alternately perform adsorption and regeneration in groups, and sequentially performing forward depressurization, reverse depressurization, vacuum desorption, and flushing regeneration operations on the adsorption towers in the regeneration state; and an automatic control step: monitoring the feed parameters of the pretreatment step in real time and automatically controlling the switching of adsorption towers and the regeneration conditions.
[0014] In some embodiments, in the multi-stage adsorption step, the pretreated gas is sequentially passed through a first adsorption tower, a second adsorption tower, and a third adsorption tower. In the first adsorption tower, an activated carbon-based adsorbent is used for adsorption; in the second adsorption tower, a modified molecular sieve adsorbent is used for adsorption; and in the third adsorption tower, an alkaline composite solid adsorbent is used for adsorption.
[0015] In some embodiments, an interlocking bypass step is also included: when the adsorption system fails or the operating conditions are abnormal, the feed gas is switched to a bypass channel that bypasses all adsorption towers; the bypass channel is an emergency bypass pipeline connecting the feed main and the discharge main, and the switching operation includes: opening the emergency bypass valve on the emergency bypass pipeline and closing the branch shut-off valves at the inlet and outlet of each adsorption tower.
[0016] The dry carbon dioxide removal system for olefin feed gas provided above, in this embodiment, by setting up a pretreatment unit, can remove free water and heavy hydrocarbon droplets entrained in the feed gas, thereby protecting subsequent adsorption units and extending the service life of the adsorbent; by setting up an adsorption unit including at least two adsorption towers connected in series, it achieves stepwise deep removal of carbon dioxide, achieving the beneficial effect of high decarbonization accuracy; by setting up a pressure swing regeneration unit connected to each adsorption tower, it controls the adsorption towers to perform adsorption and regeneration in groups alternately, realizing online regeneration of the adsorbent and continuous operation of the system without the need to stop the system to replace the adsorbent; by setting up an automatic control unit that is communicatively connected to the pretreatment unit, adsorption unit and pressure swing regeneration unit, it monitors the feed parameters in real time and automatically controls the switching and regeneration conditions of the adsorption towers, achieving the beneficial effects of fully automatic and stable operation, strong adaptability to operating conditions and simple operation and maintenance. Attached Figure Description
[0017] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, and the same or corresponding reference numerals denote the same or corresponding parts, wherein:
[0018] Figure 1 A schematic diagram of a dry carbon dioxide removal system for olefin feed gas according to an embodiment of this application is shown. Figure 2 A flowchart illustrating the method for removing carbon dioxide using the above-described removal system according to an embodiment of this application is shown.
[0019] In the diagram: 100, Dry carbon dioxide removal system for olefin feed gas; 101. Pretreatment unit; 102. Adsorption unit; 103. Pressure swing regeneration unit; 1021, First adsorption tower; 1022, Second adsorption tower; 1023, Third adsorption tower. Detailed Implementation
[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0021] It should be understood that the terms "comprising" and "including" used in the specification and claims of this application indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0022] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this specification and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.
[0023] As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."
[0024] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0025] like Figure 1 As shown, in some embodiments, this application provides a dry carbon dioxide removal system 100 for olefin feed gas, comprising: a pretreatment unit 101 for removing free water and heavy hydrocarbon droplets entrained in the olefin-containing feed gas; an adsorption unit 102 comprising at least two adsorption towers connected in series, each adsorption tower being filled with a composite adsorbent for adsorbing carbon dioxide; a pressure swing regeneration unit 103 connected to each adsorption tower of the adsorption unit 102 for controlling the adsorption towers to alternately perform adsorption and regeneration; and an automatic control unit communicatively connected to the pretreatment unit 101, the adsorption unit 102, and the pressure swing regeneration unit 103, and for real-time monitoring of the feed parameters of the pretreatment unit 101 and automatically controlling the switching and regeneration conditions of the adsorption towers.
[0026] In this application, the dry carbon dioxide removal system 100 for olefin feed gas includes a pretreatment unit 101, an adsorption unit 102, a pressure swing regeneration unit 103, and an automatic control unit. Specifically, the pretreatment unit 101 removes free water and heavy hydrocarbon droplets entrained in the olefin-containing feed gas to protect subsequent adsorption stages and extend the adsorbent's lifespan. The adsorption unit 102 includes at least two adsorption towers connected in series, such as a coarse adsorption tower and a fine adsorption tower. Each adsorption tower is filled with the same or different adsorbents for adsorbing carbon dioxide, thereby progressively purifying the olefin gas to meet the required carbon dioxide content.
[0027] The pressure swing regeneration unit 103 is connected to each adsorption tower of the adsorption unit 102 and is used to control the adsorption towers to perform adsorption and regeneration in groups. For example, a multi-tower parallel alternating operation mode is adopted, with matching forward discharge, reverse discharge, vacuuming and flushing regeneration pipelines. When one group of adsorption towers is performing decarbonization adsorption, another group of corresponding towers sequentially performs forward discharge depressurization, reverse discharge depressurization, vacuuming desorption and flushing regeneration operations, so that the adsorbent is regenerated online and ready for use, thereby realizing continuous operation without stopping the machine to replace the adsorbent.
[0028] The automatic control unit is communicatively connected to the pretreatment unit 101, the adsorption unit 102, and the pressure swing regeneration unit 103. It monitors the feed parameters of the pretreatment unit 101 (such as feed gas volume, pressure, carbon dioxide content, etc.) as well as the pressure difference of the adsorption tower and the outlet purity in real time. It also automatically controls the switching of the adsorption tower, the opening and closing of valves, and the regeneration conditions. At the same time, it can have overpressure and over-limit alarms and interlocking cut-off functions to ensure the safe and stable operation of the system.
[0029] The solution of this application, by setting up a pretreatment unit 101, can remove free water and heavy hydrocarbon droplets entrained in the feed gas, thereby protecting the subsequent adsorption unit 102 and extending the service life of the adsorbent. By setting up an adsorption unit 102 including at least two adsorption towers connected in series, it achieves the progressive deep removal of carbon dioxide, achieving the beneficial effect of high decarbonization accuracy. By setting up a pressure swing regeneration unit 103 connected to each adsorption tower, it controls the adsorption towers to perform adsorption and regeneration in groups alternately, realizing online regeneration of the adsorbent and continuous operation of the system without the need for downtime to replace the adsorbent. By setting up an automatic control unit that is communicatively connected to the pretreatment unit 101, adsorption unit 102 and pressure swing regeneration unit 103, it monitors the feed parameters in real time and automatically controls the switching and regeneration conditions of the adsorption towers, achieving the goals of fully automatic and stable operation, strong adaptability to operating conditions and simple operation and maintenance. In summary, this application takes into account high decarbonization accuracy, continuous and stable operation and high degree of automation. At the same time, since the entire process adopts a dry process, no wastewater or waste liquid is generated, which has the advantages of being clean and environmentally friendly, low energy consumption and high olefin recovery rate.
[0030] In one specific embodiment, the adsorption unit 102 includes a first adsorption tower 1021, a second adsorption tower 1022, and a third adsorption tower 1023 connected in series; wherein the first adsorption tower 1021 is filled with an activated carbon-based adsorbent, the second adsorption tower 1022 is filled with a modified molecular sieve adsorbent, and the third adsorption tower 1023 is filled with an alkaline composite solid adsorbent.
[0031] In one specific embodiment of the adsorption unit 102 in this application, the adsorption unit 102 includes a first adsorption tower 1021, a second adsorption tower 1022, and a third adsorption tower 1023 connected in series. The first adsorption tower 1021 is filled with an activated carbon-based adsorbent, which has a high adsorption capacity and is used for coarse removal of carbon dioxide from the raw gas, initially removing most of the carbon dioxide. The second adsorption tower 1022 is filled with a modified molecular sieve adsorbent, which has good adsorption selectivity and is used for fine removal of the gas after treatment by the first adsorption tower 1021, further reducing the carbon dioxide content. The third adsorption tower 1023 is filled with an alkaline composite solid adsorbent, which has a strong affinity for carbon dioxide and is used for deep purification of the gas, removing the carbon dioxide content to below the target value.
[0032] The scheme in this application, through the series arrangement of the above-mentioned three-stage adsorption towers and the step-by-step purification effect, can achieve high-precision removal of carbon dioxide from olefin feed gas, meeting the requirements of subsequent processes for feed purity.
[0033] In one specific implementation, the pretreatment unit 101 includes a gas-liquid separator connected in series with an olefin-containing feed gas pipeline.
[0034] In this application, the pretreatment unit 101 includes a gas-liquid separator. This gas-liquid separator is connected in series to the feed pipeline containing olefins. In use, the feed gas first enters the gas-liquid separator, where free water and heavy hydrocarbon droplets entrained in the feed gas are removed. The pretreated gas then enters the subsequent adsorption unit 102.
[0035] The proposed solution, by setting up a gas-liquid separator, can effectively protect the adsorbent in the subsequent adsorption stage, preventing free water and heavy hydrocarbon droplets from contaminating or damaging the adsorbent, thereby extending the service life of the adsorbent and ensuring long-term stable operation of the system.
[0036] In one specific implementation, the pressure swing regeneration unit 103 includes a forward discharge pipeline, a reverse discharge pipeline, a vacuum pumping pipeline, and a flushing regeneration pipeline connected to each adsorption tower, and a vacuum pump connected to the vacuum pumping pipeline. The pressure swing regeneration unit 103 is used to perform forward discharge depressurization, reverse discharge depressurization, vacuum desorption, and flushing regeneration operations on each adsorption tower separately and sequentially. The forward discharge pipeline, reverse discharge pipeline, vacuum pumping pipeline, and flushing regeneration pipeline each include branches connected to each adsorption tower and a main pipe that merges the branches. Each branch is equipped with a control valve. The main pipe of the forward discharge pipeline is connected to a forward discharge buffer tank or a venting pipeline, the main pipe of the reverse discharge pipeline is connected to a venting or recovery system, the main pipe of the vacuum pumping pipeline is connected to the vacuum pump, and the main pipe of the flushing regeneration pipeline is connected to a flushing gas source.
[0037] In the scheme of this application, the pressure swing regeneration unit 103 is a centrally set regeneration system, which is connected to each adsorption tower in the multi-stage series adsorption unit 102, and multiple adsorption towers share one pressure swing regeneration unit 103. The independent regeneration operation of each adsorption tower is realized by switching valve groups.
[0038] Specifically, the transformer regeneration unit 103 includes a forward discharge pipeline, a reverse discharge pipeline, a vacuum pumping pipeline, a flushing and regeneration pipeline, and a vacuum pump connected to the vacuum pumping pipeline. The forward discharge pipeline includes forward discharge branches connected to each adsorption tower and a main forward discharge pipeline connecting these branches to a forward discharge buffer tank or vent line; each forward discharge branch is equipped with a forward discharge control valve. The reverse discharge pipeline includes reverse discharge branches connected to each adsorption tower and a main reverse discharge pipeline connecting these branches to a vent or recovery system; each reverse discharge branch is equipped with a reverse discharge control valve. The vacuum pumping pipeline includes vacuum pumping branches connected to each adsorption tower and a main vacuum pumping pipeline connecting these branches to a vacuum pump; each vacuum pumping branch is equipped with a vacuum pumping control valve. The flushing and regeneration pipeline includes flushing branches connected to each adsorption tower and a main flushing pipeline connecting these branches to a flushing gas source; each flushing branch is equipped with a flushing control valve.
[0039] When a certain adsorption tower needs to be regenerated, the pressure swing regeneration unit 103 controls the corresponding valves on each branch connected to the adsorption tower to perform the following operations in sequence: First, open the forward discharge control valve to discharge the gas in the adsorption tower in the forward direction to the forward discharge buffer tank or vent line, thereby achieving forward discharge pressure reduction; Second, open the reverse discharge control valve to discharge the gas in the tower in the reverse direction to the vent or recovery system, thereby achieving reverse discharge pressure reduction; Then, close the forward discharge control valve and the reverse discharge control valve, open the vacuum control valve and start the vacuum pump to perform vacuum desorption on the adsorption tower, so that the adsorbed carbon dioxide is fully desorbed and discharged; Finally, close the vacuum control valve, open the flushing control valve, and introduce flushing gas from the flushing gas source to flush and regenerate the adsorbent.
[0040] The proposed solution utilizes forward discharge pipelines, reverse discharge pipelines, vacuum pipelines, and flushing and regeneration pipelines to enable online regeneration of the adsorbent in each adsorption tower. This ensures that the adsorption towers can be cyclically put into adsorption operation, achieving continuous system operation. Furthermore, since multiple adsorption towers share a single pressure swing regeneration unit 103 and regeneration is performed in a time-sharing manner via valve switching, both the system's compact structure and the continuous operation of alternating adsorption and regeneration in groups of adsorption towers are maintained.
[0041] It is worth noting that the present application does not limit the specific configuration of the pressure swing regeneration unit 103. In other embodiments, a separate pressure swing regeneration unit 103 can be provided for each adsorption tower. Specifically, each adsorption tower is equipped with independent forward discharge pipelines, reverse discharge pipelines, vacuum pumping pipelines, flushing and regeneration pipelines, and a vacuum pump connected to the vacuum pumping pipeline. The regeneration operations of each adsorption tower do not interfere with each other. This implementation allows for precise and independent control of the regeneration process of each adsorption tower, facilitating flexible adjustment of the regeneration sequence according to the different adsorption saturation levels of each tower. It is particularly suitable for scenarios with a small number of adsorption towers or high requirements for regeneration flexibility.
[0042] In one specific implementation, the system also includes an interlocking bypass unit, which includes an emergency bypass pipe connected between the feed main pipe and the discharge main pipe, an emergency bypass valve installed on the emergency bypass pipe, and branch shut-off valves installed on the inlet pipe and outlet pipe of each adsorption tower.
[0043] In the scheme of this application, the system also includes an interlocking bypass unit. The interlocking bypass unit includes an emergency bypass pipeline connected between the feed main and the discharge main, an emergency bypass valve installed on the emergency bypass pipeline, and branch shut-off valves installed on the inlet and outlet pipelines of each adsorption tower.
[0044] During normal operation, the emergency bypass valve is closed, and the branch shut-off valves are open, allowing the raw gas to flow sequentially through each adsorption tower to remove carbon dioxide. When the adsorption system malfunctions, requires adsorbent replacement, or experiences abnormal operating conditions, the emergency bypass valve is quickly opened, while the branch shut-off valves at the inlet and outlet of each adsorption tower are closed. This allows the raw gas to be directly transported from the feed main to the discharge main via the emergency bypass pipeline, bypassing all adsorption towers and reaching subsequent stages.
[0045] The solution proposed in this application, by setting up an interlocking bypass unit, can ensure the continuous operation of the olefin separation unit when the decarbonization system fails to function properly, thus avoiding the shutdown of the entire unit due to a failure of the decarbonization system.
[0046] In some embodiments, this application provides an olefin separation device, including an olefin separation main unit, characterized in that it further includes the above-mentioned carbon dioxide dry removal system 100 for olefin feed gas, wherein the inlet of the carbon dioxide dry removal system is connected to the olefin-containing feed gas pipeline, and its outlet is connected to the feed inlet of the olefin separation main unit.
[0047] In this application, the olefin separation unit includes a main olefin separation device and the aforementioned dry carbon dioxide removal system 100 for olefin feed gas. The inlet of the dry carbon dioxide removal system is connected to the olefin-containing feed gas pipeline, and the outlet of the dry carbon dioxide removal system is connected to the inlet of the main olefin separation device. The olefin-containing feed gas first enters the dry carbon dioxide removal system; after carbon dioxide removal, the purified gas then enters the main olefin separation device for subsequent olefin separation operations.
[0048] The proposed solution integrates a dry carbon dioxide removal system into the olefin separation unit and arranges it in series upstream of the main olefin separation equipment. This effectively removes carbon dioxide impurities from the feed gas, preventing carbon dioxide from poisoning and deactivating the catalysts in subsequent olefin separation and polymerization processes, thereby ensuring the stable operation of the olefin separation unit and product quality.
[0049] like Figure 2 As shown, in some embodiments, this application provides a method for removing carbon dioxide using the above-described dry carbon dioxide removal system 100 for olefin feed gas, characterized by the following steps: a pretreatment step: introducing olefin-containing feed gas into a pretreatment unit 101 to remove free water and heavy hydrocarbon droplets; a multi-stage adsorption step: allowing the pretreated gas to flow into the adsorption unit 102 for stepwise removal of carbon dioxide; a pressure swing regeneration step: controlling the adsorption towers of the adsorption unit 102 to alternately perform adsorption and regeneration in groups, and sequentially performing forward depressurization, reverse depressurization, vacuum desorption, and flushing regeneration operations on the adsorption towers in the regeneration state; and an automatic control step: monitoring the feed parameters of the pretreatment step in real time and automatically controlling the switching of adsorption towers and the regeneration conditions.
[0050] In the scheme of this application, the method for removing carbon dioxide using the above-mentioned dry carbon dioxide removal system 100 for olefin feed gas includes the following steps: a pretreatment step, in which the olefin-containing feed gas is introduced into the pretreatment unit 101 to remove free water and heavy hydrocarbon droplets entrained in the feed gas, so as to protect the subsequent adsorption unit 102 and extend the service life of the adsorbent; a multi-stage adsorption step, in which the pretreated gas flows into the multi-stage series adsorption unit 102, and the gas flows through at least two series adsorption towers in sequence, and the composite adsorbent filled in each adsorption tower adsorbs and removes carbon dioxide step by step, thereby achieving high-precision removal of carbon dioxide. The pressure swing regeneration step controls the adsorption towers of adsorption unit 102 to alternately perform adsorption and regeneration in groups. For the adsorption towers in the regeneration state, sequential operations of forward depressurization, reverse depressurization, vacuum desorption, and rinsing regeneration are performed. Specifically, the pressure inside the tower is first released in the forward direction through the forward depressurization pipeline, then the pressure is released in the reverse direction through the reverse depressurization pipeline, then the vacuum pump is started to perform vacuum desorption to desorb carbon dioxide, and finally rinsing gas is introduced to rinse and regenerate the adsorbent, thereby completing the online regeneration of the adsorbent and ensuring that the adsorption towers can be used for adsorption work in cycles. The automatic control step monitors the feed parameters of the pretreatment step (including feed gas volume, pressure, carbon dioxide content, etc.) in real time and automatically controls the switching of adsorption towers and the regeneration conditions to achieve fully automatic and stable operation.
[0051] The proposed solution, through the above steps, can continuously and efficiently remove carbon dioxide from olefin feed gas under dry conditions, without generating wastewater or waste liquid, achieving high decarbonization accuracy and stable operation.
[0052] In one specific implementation, in the multi-stage adsorption step, the pretreated gas is sequentially passed through a first adsorption tower 1021, a second adsorption tower 1022, and a third adsorption tower 1023. In the first adsorption tower 1021, an activated carbon-based adsorbent is used for adsorption; in the second adsorption tower 1022, a modified molecular sieve adsorbent is used for adsorption; and in the third adsorption tower 1023, an alkaline composite solid adsorbent is used for adsorption.
[0053] In this application, the pretreated gas flows sequentially through a first adsorption tower 1021, a second adsorption tower 1022, and a third adsorption tower 1023. Specifically, in the first adsorption tower 1021, the pretreated gas is adsorbed using an activated carbon-based adsorbent, which has a high adsorption capacity and can initially remove most of the carbon dioxide from the raw gas, achieving coarse removal. In the second adsorption tower 1022, a modified molecular sieve adsorbent is adsorbed, which has good adsorption selectivity and can further reduce the carbon dioxide content in the gas, achieving fine removal. In the third adsorption tower 1023, an alkaline composite solid adsorbent is adsorbed, which has a strong affinity for carbon dioxide and can deeply remove carbon dioxide to below the target value, achieving deep purification.
[0054] The scheme of this application, through the stepwise adsorption of the above three-stage adsorption tower, utilizes the complementary advantages of different adsorbents in adsorption capacity, selectivity and precision, and can achieve high-precision removal of carbon dioxide from olefin feed gas.
[0055] In one specific implementation, an interlocking bypass step is also included: when the adsorption system fails or the operating conditions are abnormal, the feed gas is switched to a bypass channel that bypasses all adsorption towers; the bypass channel is an emergency bypass pipeline connecting the feed main and the discharge main, and the switching operation includes: opening the emergency bypass valve on the emergency bypass pipeline and closing the branch shut-off valves at the inlet and outlet of each adsorption tower.
[0056] In the scheme of this application, when the adsorption system malfunctions, requires adsorbent replacement, or experiences abnormal operating conditions, the feed gas is switched to a bypass channel that bypasses all adsorption towers. This bypass channel is an emergency bypass pipeline connecting the feed main and the discharge main. The switching operation includes: opening the emergency bypass valve on the emergency bypass pipeline, and simultaneously closing the branch shut-off valves at the inlet and outlet of each adsorption tower. At this time, the feed gas no longer enters each stage of the adsorption tower, but is directly transported from the feed main to the discharge main via the emergency bypass pipeline, bypassing all adsorption towers and being sent to subsequent stages.
[0057] The solution proposed in this application, through the aforementioned interlocking bypass steps, can quickly switch the circuit when the decarbonization system fails to operate normally, ensuring the continuous operation of the olefin separation unit and avoiding the shutdown of the entire unit due to a failure of the decarbonization system.
[0058] In one specific implementation, the operating conditions of the method are: operating pressure of 0.8~2.5MPa, operating temperature of 35~45℃, and carbon dioxide content in the feed ≤500ppm.
[0059] In this application, the operating conditions of the above method are: operating pressure of 0.8~2.5MPa, operating temperature of 35~45℃ (e.g., 40℃), and carbon dioxide content in the feed ≤500ppm. Under these operating conditions, the feed gas enters the system in a gaseous state, resulting in high carbon dioxide adsorption and removal efficiency, while the adsorbent maintains good adsorption capacity and service life. It should be noted that the operating pressure, operating temperature, and feed carbon dioxide content can be adjusted within a certain range according to actual operating conditions. When the carbon dioxide content in the feed fluctuates or the operating load changes, the system automatically adjusts the operating parameters in real time through the control unit to ensure that the carbon dioxide content in the purified olefin gas still meets the process requirements.
[0060] While numerous embodiments of this application have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will arise for those skilled in the art without departing from the spirit and intent of this application. It should be understood that various alternatives to the embodiments of this application described herein may be employed in the practice of this application. The appended claims are intended to define the scope of protection of this application and therefore cover equivalents or alternatives within the scope of these claims.
Claims
1. A dry carbon dioxide removal system (100) for olefin feedstock gas, characterized in that, include: The pretreatment unit (101) is used to remove free water and heavy hydrocarbon droplets entrained in the olefin-containing feed gas; The adsorption unit (102) includes at least two adsorption towers connected in series, each adsorption tower being filled with a composite adsorbent for adsorbing carbon dioxide. A pressure swing regeneration unit (103), connected to each adsorption tower of the adsorption unit (102), is used to control the adsorption towers to alternately perform adsorption and regeneration in groups; and An automatic control unit is communicatively connected to the pretreatment unit (101), the adsorption unit (102), and the pressure swing regeneration unit (103), and monitors the feed parameters of the pretreatment unit (101) in real time and automatically controls the switching of the adsorption tower and the regeneration conditions.
2. The dry carbon dioxide removal system according to claim 1, characterized in that, The adsorption unit (102) includes a first adsorption tower (1021), a second adsorption tower (1022), and a third adsorption tower (1023) connected in series; wherein the first adsorption tower (1021) is filled with activated carbon-based adsorbent, the second adsorption tower (1022) is filled with modified molecular sieve adsorbent, and the third adsorption tower (1023) is filled with alkaline composite solid adsorbent.
3. The dry carbon dioxide removal system according to claim 1, characterized in that, The pretreatment unit (101) includes a gas-liquid separator connected in series to the feed gas pipeline containing olefins.
4. The dry carbon dioxide removal system according to claim 1, characterized in that, The pressure swing regeneration unit (103) includes a forward discharge pipeline, a reverse discharge pipeline, a vacuum pumping pipeline and a flushing and regeneration pipeline connected to each adsorption tower, and a vacuum pump connected to the vacuum pumping pipeline. The pressure swing regeneration unit (103) is used to perform forward discharge depressurization, reverse discharge depressurization, vacuum desorption and flushing and regeneration operations on each adsorption tower in turn.
5. The dry carbon dioxide removal system according to claim 4, characterized in that, The forward discharge pipeline, reverse discharge pipeline, vacuum pipeline, and flushing and regeneration pipeline all include branches that correspond one-to-one with each adsorption tower and a main pipe that connects all branches. Each branch is equipped with a control valve. The main pipe of the forward discharge pipeline is connected to the forward discharge buffer tank or venting pipeline, the main pipe of the reverse discharge pipeline is connected to the venting or recovery system, the main pipe of the vacuum pipeline is connected to the vacuum pump, and the main pipe of the flushing and regeneration pipeline is connected to the flushing gas source.
6. The dry carbon dioxide removal system according to any one of claims 1-5, characterized in that, It also includes an interlocking bypass unit, which includes an emergency bypass pipeline connecting the feed main and the discharge main, an emergency bypass valve installed on the emergency bypass pipeline, and branch shut-off valves installed on the inlet and outlet pipelines of each adsorption tower.
7. An olefin separation apparatus, comprising a main olefin separation unit, characterized in that, It also includes a dry carbon dioxide removal system (100) for olefin feed gas according to any one of claims 1 to 6, wherein the inlet of the dry carbon dioxide removal system is connected to an olefin-containing feed gas pipeline, and its outlet is connected to the feed inlet of the olefin separation main unit.
8. A method for removing carbon dioxide using the dry carbon dioxide removal system (100) for olefin feed gas according to any one of claims 1-6, characterized in that, Includes the following steps: Pretreatment steps: The olefin-containing feed gas is introduced into the pretreatment unit (101) to remove free water and heavy hydrocarbon droplets; Multi-stage adsorption steps: The pretreated gas is fed into the adsorption unit (102) for the stepwise removal of carbon dioxide; Pressure swing regeneration steps: The adsorption towers of the adsorption unit (102) are controlled to alternately perform adsorption and regeneration in groups. The adsorption towers in the regeneration state are subjected to forward depressurization, reverse depressurization, vacuum desorption, and rinsing regeneration operations in sequence; and Automatic control steps: Real-time monitoring of feed parameters in the pretreatment step, and automatic control of adsorption tower switching and regeneration conditions.
9. The method according to claim 8, characterized in that, In the multi-stage adsorption step, the pretreated gas is sequentially passed through a first adsorption tower (1021), a second adsorption tower (1022), and a third adsorption tower (1023). In the first adsorption tower (1021), an activated carbon-based adsorbent is used for adsorption; in the second adsorption tower (1022), a modified molecular sieve adsorbent is used for adsorption; and in the third adsorption tower (1023), an alkaline composite solid adsorbent is used for adsorption.
10. The method according to claim 8, characterized in that, It also includes an interlocking bypass procedure: when the adsorption system malfunctions or the operating conditions are abnormal, the feed gas is switched to a bypass channel that bypasses all adsorption towers; The bypass channel is an emergency bypass pipeline connecting the feed main pipe and the discharge main pipe. The switching operation includes: opening the emergency bypass valve on the emergency bypass pipeline and closing the branch shut-off valves at the inlet and outlet of each adsorption tower.