A gas phase delivery system for an ethylene plant

Abstract

This utility model relates to the field of petrochemical technology, and more particularly to a gas phase conveying system for an ethylene plant. The system includes a ROG butane desane tower, a condenser, a feed tank, a first heater, and a cracking furnace. The outlet of the ROG butane desane tower is connected in parallel to the condenser and a gas phase pipeline. A portion of the gas phase at the top of the tower is condensed by the condenser; a portion of the condensed liquid phase is then returned to the tower, while the remaining liquid phase enters the feed tank, is heated and converted into gas phase, and then enters the cracking furnace. Another portion of the gas phase at the top of the tower directly enters the cracking furnace through a fourth pipeline. By externally conveying the gas phase of the material at the top of the tower, the condensation and vaporization process of this portion of the material is reduced, lowering the consumption of cooling water and steam, thereby significantly reducing energy consumption.

Description

Technical Field

[0001] This utility model relates to the field of petrochemical technology, and more specifically, to a gas phase conveying system for an ethylene plant. Background Technology

[0002] The goal of an ethylene plant is to produce ethylene by cracking qualified petroleum feedstocks that have undergone preliminary separation. Ethylene plants use a variety of feedstocks with complex compositions. The ROG butanizer aims to separate materials containing three carbon atoms (C3, such as propane and propylene) and four carbon atoms (C4, such as butane and butene) from the ROG refinery dry gas and send them as semi-finished products to the next stage. The cracking furnace then performs high-temperature cracking of these C3 and C4 materials to obtain as much ethylene, propylene, and other products as possible.

[0003] Traditional methods use liquid-phase feeding. The C3 and C4 at the top of the column are completely condensed in the overhead condenser, and a portion is sent to the cracking furnace feed tank. The evaporator in the cracking furnace feed tank then converts the liquid phase into a gaseous phase before feeding it into the cracking furnace. This method involves unnecessary condensation and vaporization processes, increasing energy consumption. Furthermore, the complete condensation of the gaseous phase at the top of the butane de-butane column results in a high load on the overhead condenser, which can lead to insufficient cooling capacity at the top of the de-butane column in summer, causing fluctuations in overhead temperature and pressure, and consequently, product quality. Summary of the Invention

[0004] In view of the technical problem of high energy consumption caused by the complete liquefaction and regasification of gas at the top of the tower in the prior art, a gas phase conveying system for ethylene plants is provided.

[0005] The technical means adopted in this utility model are as follows:

[0006] An ethylene plant gas-phase conveying system includes a ROG butane desane tower, a condenser, a feed tank, a first heater, and a cracking furnace. The outlet of the ROG butane desane tower is connected in parallel to a fourth pipeline and a second pipeline. The condenser is installed on the second pipeline. The outlet of the second pipeline is connected in parallel to a sixth pipeline and a seventh pipeline. The outlet of the sixth pipeline is connected to the inlet of the ROG butane desane tower. The outlet of the seventh pipeline is connected to the material inlet of the feed tank. An eighth pipeline is connected between the heating outlet and the heating inlet of the feed tank. The first heater is installed on the eighth pipeline. The material outlet of the feed tank and the outlet of the fourth pipeline are connected to the inlet of the cracking furnace.

[0007] Furthermore, it also includes a reflux tank and a fifth pipeline. The outlet end of the ROG debutanizer is connected in parallel to the first pipeline and the second pipeline. The outlet end of the first pipeline is connected in parallel to the third pipeline and the fourth pipeline. The outlet ends of the third pipeline and the second pipeline are connected to the inlet end of the reflux tank through the fifth pipeline. The outlet end of the fifth pipeline is connected in parallel to the sixth pipeline and the seventh pipeline.

[0008] Furthermore, the fourth pipeline and the outlet end of the feed tank are connected to the ninth pipeline, the outlet end of the ninth pipeline is connected to the inlet end of the pyrolysis furnace, and a second heater is installed on the ninth pipeline.

[0009] Furthermore, a regulating valve is installed on the first pipeline, and the outlet end of the regulating valve is connected to the inlet ends of the third and fourth pipelines through the first pipeline.

[0010] Furthermore, a delivery pump is installed on the sixth pipeline, and the outlet end of the delivery pump is connected to the inlet end of the ROG debutanizer via the sixth pipeline.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] A portion of the gas phase at the top of the ROG butane degasser is condensed into a liquid phase by a condenser, and the liquid phase is returned to the ROG butane degasser. The other portion of the gas phase at the top of the ROG butane degasser is directly introduced into the cracking furnace through the fourth pipeline. This reduces the amount of material that has been condensed and gasified, thereby reducing the energy required for condensation and gasification, lowering costs, and improving production efficiency. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of a gas phase conveying system for an ethylene plant according to the present invention.

[0015] In the diagram: 1. ROG butanizer; 2. Condenser; 3. Feed tank; 4. First heater; 5. Second heater; 6. Cracking furnace; 7. First pipeline; 8. Control valve; 9. Second pipeline; 10. Third pipeline; 11. Fourth pipeline; 12. Fifth pipeline; 13. Sixth pipeline; 14. Seventh pipeline; 15. Eighth pipeline; 16. Reflux tank; 17. Transfer pump; 18. Ninth pipeline. Detailed Implementation

[0016] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] like Figure 1As shown in the figure, this utility model discloses a gas phase conveying system for an ethylene plant, including an ROG butane desanostat 1, a condenser 2, a feed tank 3, a first heater 4, and a cracking furnace 6. The outlet end of the ROG butane desanostat 1 is connected in parallel to a first pipeline 7 and a second pipeline 9. The outlet end of the first pipeline 7 is connected in parallel to a third pipeline 10 and a fourth pipeline 11. The outlet ends of the third pipeline 10 and the second pipeline 9 are connected to the inlet end of a fifth pipeline 12. A reflux tank 16 is installed on the fifth pipeline 12. The outlet ends of the second pipeline 9 and the third pipeline 10 are connected to the inlet end of the reflux tank 16 through the fifth pipeline 12. The outlet end of the reflux tank 16 is connected in parallel to a sixth pipeline 13 and a seventh pipeline 14 through the fifth pipeline 12. The outlet end of the sixth pipeline 13 is connected to the inlet end of the ROG butane desanostat 1. A transfer pump 17 is installed on the sixth pipeline 13. The outlet end of the transfer pump 17 is connected to the inlet end of the ROG butane desanostat 1 through the sixth pipeline 13. The outlet end of the seventh pipe 14 is connected to the material inlet end of the feed tank 3. The heating outlet end and the heating inlet end of the feed tank 3 are connected to the eighth pipe 15. The first heater 4 is installed on the eighth pipe 15. The material outlet end of the feed tank 3 is connected to the inlet end of the pyrolysis furnace 6. The fourth pipe 11 and the outlet end of the feed tank 3 are connected to the ninth pipe 18. The outlet end of the ninth pipe 18 is connected to the inlet end of the pyrolysis furnace 6. The second heater 5 is installed on the ninth pipe 18. A regulating valve 8 is installed on the first pipe 7. The outlet end of the regulating valve 8 is connected to the inlet ends of the third pipe 10 and the fourth pipe 11 through the first pipe 7.

[0018] Working principle:

[0019] The gas produced in the ROG butane removal column 1 is split by the first pipeline 7 and the second pipeline 9. A portion of the gas is condensed into liquid by the condenser 2 via the second pipeline 9 and stored in the reflux tank 16. The liquid in the reflux tank 16 is then pumped back into the ROG butane removal column 1 by the transfer pump 17 to maintain the gas-liquid balance and mass and heat transfer processes within the column, ensuring the separation effect. The separation process in the butane removal column is based on the different volatility of the components in the mixture. The condensed liquid phase is returned to the column via top reflux, where it contacts the rising gas phase on the trays or packing for mass and heat transfer. This allows heavier components (such as C5) in the gas phase to be further condensed, while lighter components (such as C3 and C4) in the liquid phase are vaporized, achieving more efficient separation. As the reflux liquid descends, it absorbs heat from the rising gas phase, causing the temperature inside the column to gradually increase from the top to the bottom, forming a reasonable temperature gradient. This helps ensure effective separation of the components on different trays and avoids adverse effects of temperature fluctuations on the separation effect.

[0020] The regulating valve on the first pipeline 7 can adjust the flow rate of the first pipeline 7 to make the system more stable. The gas phase in the first pipeline 7 is split by the third pipeline 10 and the fourth pipeline 11. The gas phase in the third pipeline 10 enters the reflux tank 16 to ensure the pressure in the reflux tank 16 is stable. Part of the liquid phase in the reflux tank 16 is pumped into the ROG debutanizer 1 by the transfer pump 17, and the other part enters the feed tank 3 through the seventh pipeline 14. After being heated by the first heater 4, it changes from liquid phase to gas phase and enters the cracking furnace 6 through the ninth pipeline 18.

[0021] The gas phase in the fourth pipeline 11 directly enters the ninth pipeline 18. The gas phase in the ninth pipeline 18 is heated twice by the second heater 5 before entering the pyrolysis furnace 6, ensuring the stability of the gas phase state.

[0022] Valves, flow meters, and pressure monitoring equipment are installed on the first pipeline 7, the third pipeline 10, and the fourth pipeline 11 for monitoring and adjustment.

[0023] By implementing this utility model, the following technical effects can be achieved:

[0024] Reduced energy consumption: After the material at the top of the tower is sent out in gaseous phase, the condensation and vaporization process of this part of the material can be reduced, and the consumption of cooling water and steam can be reduced, thereby significantly reducing energy consumption.

[0025] Stable system operation: In traditional processes, the cooling water temperature at the top of the butane stripper condenser rises in summer, leading to insufficient cooling supply and drastic fluctuations in top temperature and pressure. This results in unstable operation of the butane stripper and substandard product quality. After the improvement, the cooling water consumption of the butane stripper is significantly reduced, and the cooling supply can meet normal operating requirements in summer, ensuring stable system operation and meeting product quality standards.

[0026] Addressing system bottlenecks: The load on the butanizer tower was limited by insufficient overhead cooling capacity. The improved system significantly reduced the overhead cooling capacity requirement.

[0027] Under the original process, the overhead condenser of the butane stripper used cooling water to condense all the overhead vapor phase. After implementing the new scheme, the cooling water consumption of the overhead condenser of the butane stripper can be reduced by 70% under the same operating conditions.

[0028] In the original process, the condensed liquid C3C4 was sent to the feed tank of the pyrolysis furnace. After being heated and vaporized by the heater at the bottom of the feed tank, it was sent to the feed heater of the pyrolysis furnace for temperature adjustment, and finally sent to the pyrolysis furnace. After the implementation of the new scheme, the steam consumption for heating this part of the material to the original temperature can be reduced by 85%.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A gas phase conveying system for an ethylene plant, characterized in that, The system includes an ROG butane dehydrogenator (1), a condenser (2), a feed tank (3), a first heater (4), and a cracking furnace (6). The outlet end of the ROG butane dehydrogenator (1) is connected in parallel to a fourth pipeline (11) and a second pipeline (9). The condenser (2) is installed on the second pipeline (9). The outlet end of the second pipeline (9) is connected in parallel to a sixth pipeline (13) and a seventh pipeline (14). The outlet end of the sixth pipeline (13) is connected to the inlet end of the ROG butane dehydrogenator (1). The outlet end of the seventh pipeline (14) is connected to the material inlet end of the feed tank (3). An eighth pipeline (15) is connected between the heating outlet end and the heating inlet end of the feed tank (3). The first heater (4) is installed on the eighth pipeline (15). The material outlet end of the feed tank (3) and the outlet end of the fourth pipeline (11) are connected to the inlet end of the cracking furnace (6).

2. The gas phase conveying system for an ethylene plant according to claim 1, characterized in that, It also includes a reflux tank (16) and a fifth pipeline (12). The outlet end of the ROG debutanizer (1) is connected in parallel to the first pipeline (7) and the second pipeline (9). The outlet end of the first pipeline (7) is connected in parallel to the third pipeline (10) and the fourth pipeline (11). The outlet ends of the third pipeline (10) and the second pipeline (9) are connected to the inlet end of the reflux tank (16) through the fifth pipeline (12). The outlet end of the fifth pipeline (12) is connected in parallel to the sixth pipeline (13) and the seventh pipeline (14).

3. The gas phase conveying system for an ethylene plant according to claim 1, characterized in that, The outlet end of the fourth pipeline (11) and the feed tank (3) is connected to the ninth pipeline (18), the outlet end of the ninth pipeline (18) is connected to the inlet end of the pyrolysis furnace (6), and the second heater (5) is installed on the ninth pipeline (18).

4. The gas phase conveying system for an ethylene plant according to claim 2, characterized in that, A regulating valve (8) is installed on the first pipeline (7), and the outlet end of the regulating valve (8) is connected to the inlet end of the third pipeline (10) and the fourth pipeline (11) through the first pipeline (7).

5. The gas phase conveying system for an ethylene plant according to claim 1, characterized in that, A delivery pump (17) is installed on the sixth pipeline (13), and the outlet end of the delivery pump (17) is connected to the inlet end of the ROG debutanizer (1) through the sixth pipeline (13).

Images