System capable of reducing feeding dialkene and oxide of propane dehydrogenation device
By introducing a deoxygenation bed and hydrogenation reactor system into the propane dehydrogenation unit, oxides are removed first and then dienes are converted, solving the problems of catalyst adhesion and blockage, and achieving extended catalyst life and improved production stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG PETROLEUM&CHEM CO LTD
- Filing Date
- 2025-03-24
- Publication Date
- 2026-04-21
AI Technical Summary
In existing propane dehydrogenation units, dienes and oxides in the propane feedstock can easily cause catalyst adhesion and blockage, shortening catalyst life and affecting the stable operation and economic benefits of the unit.
The system employs a deoxygenation bed and hydrogenation reactor system. First, oxides are removed through the deoxygenation bed, and then the dienes are converted into monoolefins or alkanes through the hydrogenation reactor. The system also includes a feed mixer, heater, and ethylene unit to form a closed loop, ensuring the stability of the catalyst and the continuity of production.
It extended catalyst life, improved propylene product quality and yield, reduced the number of shutdowns for maintenance, and enhanced the economic efficiency and operational stability of the plant.
Smart Images
Figure CN224142166U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of chemical production technology, specifically relating to a system that can reduce the amount of dienes and oxides in the feed of a propane dehydrogenation unit. Background Technology
[0002] Propane dehydrogenation (PDH) is an important chemical process used to convert propane into propylene. Propylene is a key raw material for the production of various plastics and chemicals, and is widely used in the manufacture of polypropylene, propylene oxide, acrylic acid, and other products. Due to its high flexibility and rapid return on investment, the PDH process has been widely adopted globally.
[0003] Because propane feedstock contains oxides and dienes, excessive dienes and oxides entering the propane dehydrogenation unit can lead to the formation of viscous heavy components such as polycyclic aromatic hydrocarbons and gums inside the reactor. This causes catalyst adhesion, hinders flow, and clogs the reactor's internal and external meshes with catalyst powder, resulting in unit shutdown. This shortens the lifespan of the propane dehydrogenation catalyst, increases shutdown and maintenance costs, severely impacts the continuous and stable operation of the unit, reduces propylene production, and significantly affects the overall economic efficiency of the unit.
[0004] When dienes from propane feed enter the propane dehydrogenation reactor, these dienes exhibit high reactivity and readily undergo polymerization. Under the high temperatures and catalytic conditions within the reactor, diene molecules can undergo addition reactions to form polymers. These polymers may deposit inside the reactor, clogging the active sites of the catalyst and the reactor's piping, reducing catalyst activity and reactor efficiency. Dienes may also undergo complex reactions with other substances within the reactor, generating gums and coke. At high temperatures, the unsaturated bonds of dienes readily undergo dehydrogenation condensation reactions. As the reaction proceeds, these condensation products continuously polymerize and cyclize, eventually forming coke. The formation of coke covers the catalyst surface, burying the active sites and leading to catalyst deactivation. This causes catalyst adhesion and poor flow, clogging of the reactor's internal and external meshes with catalyst powder. Simultaneously, the formation of gums also affects the flow of reactants, increasing the pressure drop within the reactor and potentially causing plant shutdown.
[0005] When the oxides enter the reactor, they undergo oxidation reactions with propane or intermediate products from the reaction process. If a small amount of oxygen is present as an oxide, it can partially oxidize propane to produce aldehydes. For example, propane may produce propanal in the presence of oxygen and a catalyst. If the oxides are metal oxides or other oxides, they may catalyze the formation of oxygen-containing compounds such as ketones or acids under the reaction conditions. These oxygen-containing compounds alter the composition of the reaction products, affecting the purity of propylene, and may further react, such as through the condensation of aldehydes, generating high-boiling-point impurities and increasing the difficulty of subsequent separation.
[0006] Therefore, the current propane dehydrogenation unit has a shortened operating time because the raw material propane has not been deoxideized and diene removed. Each month's reduction in operating time results in significant economic losses, and the cost of each maintenance and material repair is high. Utility Model Content
[0007] This invention addresses the aforementioned problems in the existing technology by proposing a system that can reduce the amount of dienes and oxides in the feed of a propane dehydrogenation unit.
[0008] This utility model can be achieved through the following technical solutions:
[0009] A system for reducing dienes and oxides in the feed of a propane dehydrogenation unit includes:
[0010] Deoxidation bed, in which propane is deoxidized;
[0011] A feed mixer is connected to the deoxygenation bed, in which hydrogen and propane after oxide removal are mixed;
[0012] A hydrogenation reactor, connected to the feed mixer, is used to react propane and hydrogen to remove dienes. The purified propane produced by the hydrogenation reactor is then transported to a depropanizer for separation.
[0013] As a further improvement of this utility model, at least one deoxidation bed is provided. When there are multiple deoxidation beds, each deoxidation bed is arranged in parallel and connected to the feed mixer.
[0014] As a further improvement of this utility model, a feed heater is also provided on the pipeline between the deoxidation bed and the feed mixer.
[0015] As a further improvement of this utility model, the feed heater heats the deoxide-removed propane to 35℃-45℃.
[0016] As a further improvement of this utility model, it also includes a feed dryer, which is connected to the bottom of the deoxygenation bed, and propane enters the deoxygenation bed after passing through the feed dryer.
[0017] As a further improvement of this utility model, it also includes an ethylene unit, which forms a closed-loop system with the deoxygenation bed, wherein,
[0018] The outlet of the ethylene unit is connected to the top of the deoxygenation bed;
[0019] The bottom of the deoxygenation bed is connected to the air inlet of the ethylene unit.
[0020] As a further improvement of this utility model, a regeneration gas heater is provided on the pipeline connecting the gas outlet of the ethylene unit to the deoxygenation bed.
[0021] As a further improvement of this utility model, the regenerator heater heats the fuel gas from the ethylene plant to 225°C-235°C.
[0022] As a further improvement of this utility model, a regenerated gas cooler is provided on the pipeline connecting the deoxygenation bed to the gas inlet of the ethylene unit.
[0023] As a further improvement of this utility model, the regenerated gas cooler cools the fuel gas output from the bottom of the deoxygenation bed to room temperature.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] 1. Extended catalyst life: By effectively removing dienes and oxides from propane, the poisoning effect of these impurities on the catalyst is reduced, significantly extending the service life of the propane dehydrogenation catalyst and reducing the replacement frequency and corresponding maintenance costs.
[0026] 2. Improved product quality and yield: The hydrogenation reactor successfully converted polyolefins into monoolefins or alkanes, improving the purity of propane feedstock, thereby enhancing the quality and yield of propylene products, stabilizing the production process, and reducing fluctuations caused by raw material quality issues.
[0027] 3. Reduced shutdown and maintenance frequency: Reduced equipment blockage caused by excessive impurities in raw materials, allowing the propane dehydrogenation unit to operate stably for extended periods, reducing the frequency of shutdown and maintenance, saving significant time and resources, increasing the production load of the propane dehydrogenation unit, and improving economic efficiency.
[0028] 4. Complete regeneration cycle: The deoxygenation bed and the ethylene unit form a closed-loop system, making the regeneration operation of the deoxygenation bed more efficient and environmentally friendly. The regenerated gas circulates between the ethylene unit and the deoxygenation bed, which maximizes the utilization of resources and ensures the stable operation of the system. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the system principle of the present invention, which can reduce the amount of dienes and oxides in the feed of a propane dehydrogenation unit.
[0030] In the diagram, 100 is the deoxygenation bed; 110 is the feed mixer; 120 is the hydrogenation reactor; 130 is the feed heater; 140 is the feed dryer; 150 is the ethylene unit; 160 is the regenerated gas heater; and 170 is the regenerated gas cooler. Detailed Implementation
[0031] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. The technical methods of the present invention will be further described, but the present invention is not limited to these embodiments.
[0032] like Figure 1 As shown, this utility model provides a system for reducing dienes and oxides in the feed of a propane dehydrogenation unit, comprising:
[0033] The deoxygenation bed 100 contains a special adsorbent that can selectively adsorb and remove oxides from propane, ensuring the purity of raw materials in subsequent processes.
[0034] The feed mixer 110 is connected to the deoxygenation bed 100. In this unit, high-purity hydrogen from the pipeline is filtered and then fully mixed with the deoxygenated propane. To ensure the mixing effect, a high-efficiency hydrogen mixer technology is adopted, which makes the hydrogen form micron-sized bubbles and uniformly dispersed in the propane stream, providing ideal conditions for the subsequent hydrogenation reaction.
[0035] Hydrogenation reactor 120 is connected to feed mixer 110, and the mixed propane and hydrogen enter hydrogenation reactor 120 together. Inside the reactor, under the action of a specific catalyst, polyolefins (such as MAPD) are selectively hydrogenated to monoolefins or alkanes, thereby effectively removing diene components from propane;
[0036] The operating conditions of the hydrogenation reactor 120 are set at 1.8 MPa G and 40 °C, and a hydrogen stripping system is configured to remove unreacted hydrogen from the flare system. The purified propane after the reaction flows out from the bottom of the hydrogenation reactor 120 and is ready to be sent to the depropanizer for further separation.
[0037] It should be noted that current propane dehydrogenation units are prone to catalyst adhesion and poor flow due to dienes and oxides in the propane feedstock, which can even cause equipment blockage, forcing frequent shutdowns for maintenance and increasing operating costs.
[0038] To address this problem, this embodiment provides a system capable of effectively removing oxides and dienes from propane. The deoxygenation bed 100 first removes oxides from propane through adsorption, and then the propane is further removed through a hydrogenation reactor 120. This system offers at least the following advantages:
[0039] 1. Extend catalyst life:
[0040] By effectively removing dienes and oxides from propane, the poisoning effect of these impurities on the propane dehydrogenation catalyst is reduced, significantly extending the service life of the propane dehydrogenation catalyst and reducing the replacement frequency and corresponding maintenance costs.
[0041] 2. Improve product quality and output:
[0042] The hydrogenation reactor 120 successfully converted polyolefins into monoolefins or alkanes, improving the purity of propane feedstock, thereby enhancing the quality and yield of propylene products, stabilizing the production process, and reducing fluctuations caused by raw material quality issues.
[0043] 3. Reduce the number of times the vehicle is stopped for maintenance:
[0044] This reduces equipment blockage caused by excessive impurities in raw materials, allowing the propane dehydrogenation unit to operate stably for extended periods. It also reduces the frequency of shutdowns and maintenance, saving significant time and resources, increasing the unit's production capacity, and improving economic efficiency. 4. Enhanced overall economic benefits:
[0045] In summary, the improvements mentioned above not only enhance the operating efficiency of the device but also significantly reduce operating costs, thereby increasing the economic benefits of the entire propane dehydrogenation unit. It has significant application value and promising prospects for promotion.
[0046] In addition, the reason for removing the oxides from propane before removing the diene is that if hydrogen is added first, the hydrogen will react with oxygen to produce water, and water will form toxic substances when it comes into contact with the hydrogenation catalyst. Therefore, this method of removing the oxides from propane first and then removing the diene can avoid the above-mentioned safety hazards and ensure the safe and stable operation of the entire production process.
[0047] Preferably, at least one deoxidizing bed 100 is provided. When there are multiple deoxidizing beds 100, each deoxidizing bed 100 is arranged in parallel and connected to the feed mixer 110. This means that each deoxidizing bed 100 can work independently and they share the total feed flow. The parallel arrangement increases the redundancy of the system. Even if one deoxidizing bed 100 has a problem (such as needing regeneration or maintenance), the other deoxidizing beds 100 can still continue to work, ensuring the continuity and stability of production.
[0048] Preferably, a feed heater 130 is also provided on the pipeline between the deoxidation bed 100 and the feed mixer 110. The feed heater 130 heats the deoxidized propane to 35°C-45°C. The feed heater 130 ensures that the deoxidized propane can be precisely heated to the required temperature range (35°C-45°C) before entering the feed mixer 110. Heating within this temperature range can improve the mixing uniformity of propane and hydrogen, allowing them to come into more complete contact in the feed mixer 110, creating better conditions for the subsequent hydrogenation reaction.
[0049] Preferably, it also includes a feed dryer 140, which is connected to the bottom of the deoxygenation bed 100. Propane enters the deoxygenation bed 100 after passing through the feed dryer 140. By drying the propane, on the one hand, the water can be prevented from reacting with the adsorbent in the deoxygenation bed 100, and on the other hand, the potential danger of water reacting with the hydrogenation catalyst to form toxic substances is eliminated.
[0050] Preferably, it also includes an ethylene unit 150, which forms a closed-loop system with the deoxygenation bed 100, wherein,
[0051] The outlet of the ethylene unit 150 is connected to the top of the deoxygenation bed 100, so that the gas discharged from the ethylene unit 150 (such as fuel gas) can directly enter the deoxygenation bed 100 for regeneration.
[0052] The bottom of the deoxygenation bed 100 is connected to the air inlet of the ethylene unit 150. The gas regenerated by the deoxygenation bed 100 flows out from the bottom of the deoxygenation bed 100 and then returns to the air inlet of the ethylene unit 150 through the pipeline, forming a complete circulation path.
[0053] By forming a closed-loop system with the ethylene unit 150, the regeneration operation of the deoxygenation bed 100 becomes more efficient and environmentally friendly. The regeneration gas circulates between the ethylene unit 150 and the deoxygenation bed 100, which maximizes the utilization of resources and ensures the stable operation of the system.
[0054] Preferably, a regenerator heater 160 is provided on the pipeline connecting the gas outlet of the ethylene unit 150 and the deoxygenation bed 100. The regenerator heater heats the fuel gas from the ethylene unit 150 to 225°C-235°C. This temperature range can ensure that the oxides on the adsorbent are effectively desorbed, but will not be too high to cause unnecessary side reactions or damage to the adsorbent.
[0055] Preferably, a regenerated gas cooler 170 is provided on the pipeline connecting the deoxygenation bed 100 and the air inlet of the ethylene unit 150. The regenerated gas cooler 170 cools the fuel gas output from the bottom of the deoxygenation bed 100 to room temperature. When the fuel gas at room temperature enters the ethylene unit 150, it will not cause temperature fluctuations, thus ensuring the stability of the internal operating conditions of the ethylene unit 150 and reducing the operational instability and maintenance requirements caused by temperature changes.
[0056] Furthermore, it should be noted that this design can be flexibly adjusted according to actual conditions. For example, when the ethylene unit 150 is shut down, nitrogen can be used as the regeneration gas. After being heated to 225℃-235℃ by the same steam heat exchanger, it is regenerated and then cooled before being directly discharged into the unit flare. This flexible adjustment reduces the number of shutdowns and maintenance caused by the unavailability of the ethylene unit 150, reducing maintenance costs and time. Moreover, regardless of whether fuel gas or nitrogen is used as the regeneration gas, the entire regeneration cycle can operate efficiently and stably.
[0057] The technical means disclosed in this utility model are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above are specific embodiments of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications are also considered within the scope of protection of this utility model.
[0058] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0059] Furthermore, in this utility model, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0060] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0061] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.
Claims
1. A system for reducing dienes and oxides in the feed of a propane dehydrogenation unit, characterized in that, include: Deoxidation bed, in which propane is deoxidized; A feed mixer is connected to the deoxygenation bed, in which hydrogen and propane after oxide removal are mixed; A hydrogenation reactor, connected to the feed mixer, is used to react propane and hydrogen to remove dienes. The purified propane produced by the hydrogenation reactor is then transported to a depropanizer for separation.
2. The system of claim 1, wherein the system is further configured to reduce the amount of dienes and oxygenates in the feed to the dehydrogenation unit. The number of deoxidation beds is at least one. When there are multiple deoxidation beds, they are arranged in parallel and connected to the feed mixer.
3. The system of claim 1, wherein the system is further configured to reduce the amount of dienes and oxygenates in the feed to the dehydrogenation unit. A feed heater is also provided on the pipeline between the deoxygenation bed and the feed mixer.
4. The system of claim 3, wherein the system is further configured to reduce the amount of dienes and oxygenates in the feed to the dehydrogenation unit. The feed heater heats the deoxide-removed propane to 35°C-45°C.
5. The system of claim 1, wherein the system is further configured to reduce dienes and oxygenates in the feed to the dehydrogenation unit. It also includes a feed dryer, which is connected to the bottom of the deoxygenation bed, through which propane enters the deoxygenation bed.
6. The system of claim 1, wherein the system is further configured to reduce dienes and oxygenates in the feed to the dehydrogenation unit. It also includes an ethylene unit, which forms a closed-loop system with the deoxygenation bed, wherein, The outlet of the ethylene unit is connected to the top of the deoxygenation bed; The bottom of the deoxygenation bed is connected to the air inlet of the ethylene unit.
7. The system of claim 6, wherein the system is further configured to reduce the amount of dienes and oxygenates in the feed to the dehydrogenation unit. A regenerated gas heater is installed on the pipeline connecting the gas outlet of the ethylene plant to the deoxygenation bed.
8. A system for reducing dienes and oxides in the feed of a propane dehydrogenation unit according to claim 7, characterized in that, The regenerated gas heater heats the fuel gas from the ethylene plant to 225°C-235°C.
9. The system of claim 6, wherein the system is further configured to reduce the amount of dienes and oxygenates in the feed to the dehydrogenation unit. A regenerated gas cooler is installed on the pipeline connecting the deoxygenation bed to the gas inlet of the ethylene unit.
10. The system of claim 9, wherein the system is further configured to reduce the amount of dienes and oxygenates in the feed to the dehydrogenation unit. The regenerated gas cooler cools the fuel gas output from the bottom of the deoxygenation bed to room temperature.