Efficient recovery system for tail gas of deethanizer

Abstract

The utility model discloses a deethanization tower tail gas efficient recovery system, including deethanization tower, deethanization tower is provided with raw material line, heating steam line, reboiler, output line, high pressure discharge line and atmospheric pressure discharge line, the high pressure discharge line is communicated with the exhaust gas discharge line, the output end of the exhaust gas discharge line is respectively connected with torch combustion line and tail gas recovery line, and the tail gas recovery line feeds tail gas into the combustible gas recovery line through a transfer tank. According to the high-efficiency recovery system for the tail gas of the deethanization tower, the high-pressure discharge line is arranged at the tower top, and the gas of the high-pressure discharge line is recovered for effective combustion, so that the use frequency and the combustion amount of a torch combustion line are reduced, and meanwhile, the problems of high tail gas pressure and high flow rate can be effectively avoided; and environmental pollution caused by the fact that a torch combustion line cannot be fully combusted is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas treatment of a deethanizer. Background Art

[0002] The propane dehydrogenation device uses the existing technical production technology. The by-products of the distillation section in the process flow are purified, mainly 20% hydrogen, 35% ethane, 17% ethylene, 17% methane, carbon monoxide and other combustible gases in the product are directly discharged into the flare, which wastes fuel and pollutes the environment to a certain extent. When the pressure of the deethanizer is high, the existing pressure relief pipeline cannot meet the pressure, resulting in the excess part of the deethanizer tail gas being discharged through the flare pipeline. The emission of these waste gases will cause serious environmental pollution and have certain hazards to humans and the environment. For this reason, the pressure relief pipeline method of the existing technology is technically improved so that the tail gas can be used more efficiently. Utility Model Content

[0003] The utility model aims to provide a deethanizer tail gas efficient recovery system to solve the problems raised in the above background technology.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] A deethanizer tail gas efficient recovery system comprises a deethanizer, wherein the deethanizer is provided with a raw material line, a heating steam line, a reboiler, an output line, a high-pressure discharge line and a normal-pressure discharge line, wherein the high-pressure discharge line is connected to a waste gas discharge line, and the output end of the waste gas discharge line is respectively connected to a flare combustion line and a tail gas recovery line, and the tail gas recovery line sends the tail gas to a combustible gas recovery line through a transfer tank.

[0006] As a further solution of the utility model: a pressure relief valve is installed on the flare combustion line, and when the pressure in the transfer tank is excessive, the pressure relief valve opens to send the combustible gas to the flare combustion through the flare combustion line.

[0007] As a further solution of the utility model: a distributor is also arranged in the transfer tank, the tail gas recovery line is connected with the distributor, a sprayer is installed in the transfer tank, and the bottom of the transfer tank is connected with a water outlet pipeline for discharging spray water.

[0008] As a further solution of the utility model: the atmospheric pressure discharge line is connected to the condenser, the condenser is connected to the reflux tank, and the reflux tank sends the recoverable liquid back to the deethanizer through the reflux pipeline.

[0009] As a further solution of the utility model: the condenser is equipped with a medium heat exchange pipeline, and the input end of the medium heat exchange pipeline is connected to the medium delivery pipeline.

[0010] As a further solution of the utility model: a pressure control valve is installed on the high-pressure discharge line. When the atmospheric pressure discharge line normally transports the tail gas but the deethanizer is still at high pressure, the pressure control valve opens and the tail gas is discharged through the high-pressure discharge line.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] 1. The deethanizer tail gas efficient recovery system sets a high-pressure discharge line at the top of the tower and recovers the gas from the high-pressure discharge line for effective combustion, thereby reducing the use frequency and combustion volume of the flare combustion line. At the same time, it can also effectively avoid the problem of high tail gas pressure and fast flow rate, which leads to the inability of the flare combustion line to fully burn and cause environmental pollution.

[0013] 2. The deethanizer tail gas efficient recovery system and transfer tank spraying can reduce tail gas temperature, reduce pipeline pressure, improve combustible purity, and facilitate steam collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The schematic diagram is a structural diagram of a high-efficiency recovery system for tail gas from a deethanizer.

[0015] In the figure: 1. Deethanizer; 2. Raw material line; 3. Heating steam line; 4. Atmospheric pressure discharge line; 5. Condenser; 6. Medium heat exchange pipeline; 7. Reflux tank; 8. Reflux pipeline; 9. High-pressure discharge line; 10. Pressure control valve; 11. Waste gas discharge line; 12. Output line; 13. Flare combustion line; 14. Tail gas recovery line; 15. Transfer tank; 16. Distributor; 17. Water outlet pipeline; 18. Medium delivery pipeline; 19. Combustible gas recovery line; 20. Sprinkler; 21. Reboiler. DETAILED DESCRIPTION

[0016] See also Figure 1In the embodiment of the utility model, a deethanizer tail gas efficient recovery system includes a deethanizer 1, the deethanizer 1 is provided with a raw material line 2, a heating steam line 3, a reboiler 21, an output line 12, a high-pressure discharge line 9 and a normal-pressure discharge line 4, the high-pressure discharge line 9 is connected to the exhaust gas discharge line 11, the output end of the exhaust gas discharge line 11 is respectively connected to the flare combustion line 13 and the tail gas recovery line 14, the tail gas recovery line 14 sends the tail gas to the combustible gas recovery line 19 through the transfer tank 15, the raw material line 2, the heating steam line 3, the reboiler 21, the output line 12 and the normal-pressure discharge line 4 provided in the deethanizer 1 are all prior art The normal pressure discharge line 4 is a pressure relief pipeline design of the prior art, and the high-pressure discharge line 9 of the prior art is used for tail gas pressure relief at high pressure. The high-pressure discharge line 9 sends the tail gas directly to the flare for combustion, which will cause waste of combustible gas, and if it is not completely burned, it will also cause environmental pollution. For this reason, a transfer tank 15 is installed on the exhaust gas discharge line 11. The transfer tank 15 can not only buffer the high-pressure tail gas, but also temporarily store the tail gas, and send it to the heating and temperature-raising equipment for combustion through the combustible gas recovery line 19, thereby reducing the flare combustion pressure and waste, which can not only improve the recovery efficiency of the tail gas, but also reduce environmental pollution.

[0017] In a preferred embodiment, a pressure relief valve is installed on the flare combustion line 13. When the pressure in the transfer tank 15 is excessive, the pressure relief valve opens to send the combustible gas to the flare combustion through the flare combustion line 13. The transfer tank 15 is added to the front end of the flare combustion line 13 as a combustible gas recovery device. The volume of the transfer tank 15 is set according to the existing exhaust gas production peak value and the exhaust gas combustion usage of the heating and temperature raising equipment. The flare combustion line 13 is used for emergency use. When the exhaust gas production speed exceeds the exhaust gas recovery efficiency, in order to ensure the safety of the equipment, flare combustion treatment is carried out. The existing process is used, but the frequency and duration of flare combustion are greatly reduced.

[0018] In a preferred embodiment, a distributor 16 is further provided in the transfer tank 15, the tail gas recovery line 14 is connected to the distributor 16, a sprayer 20 is installed in the transfer tank 15, and the bottom of the transfer tank 15 is connected to a water outlet pipeline 17 for discharging spray water. The tail gas generated by the propane dehydrogenation device is stored in the transfer tank 15. The tail gas stored in the transfer tank 15 contains hydrogen, ethane, ethylene, methane, carbon monoxide and other combustible gases, and its temperature is relatively increased under the influence of pressure and external environmental factors. Therefore, cooling the transfer tank 15 can improve the transportation safety, reduce gas expansion and thus reduce pipeline pressure. At the same time, it can further absorb water-soluble substances in the tail gas. Hydrogen, ethane, ethylene, methane, carbon monoxide and other major combustible gases are all substances that are difficult to dissolve in water and insoluble in water, so they will not affect the combustion efficiency of the tail gas, so that the tail gas can be efficiently stored and utilized.

[0019] In a preferred embodiment, the atmospheric pressure discharge line 4 is connected to the condenser 5, the condenser 5 is connected to the reflux tank 7, the reflux tank 7 sends the recoverable liquid back to the deethanizer 1 through the reflux pipeline 8, and the rising steam at the top of the tower is converted into liquid through the condenser 5 so as to reflux into the tower, and the separated tail gas is sent to the transfer tank 15 for recycling through the waste gas discharge line 11. The condenser 5 is equipped with a medium heat exchange pipeline 6, and the input end of the medium heat exchange pipeline 6 is connected to the medium delivery pipeline 18.

[0020] In a preferred embodiment, a pressure control valve 10 is installed on the high-pressure discharge line 9. When the atmospheric pressure discharge line 4 normally transports the tail gas but the deethanizer 1 is still under high pressure, the pressure control valve 10 opens and the tail gas is discharged through the high-pressure discharge line 9, and the pressure control valve 10 is switched according to the pressure generated by the tail gas in the deethanizer 1.

[0021] It should be noted that the above embodiments all belong to the same utility model concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference can be made to the description in other embodiments.

[0022] The above-mentioned embodiments only express the implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A deethanizer tail gas efficient recovery system, comprising a deethanizer (1), wherein the deethanizer (1) is provided with a feed line (2), a heating steam line (3), a reboiler (21), an output line (12), a high-pressure discharge line (9) and a normal-pressure discharge line (4), characterized in that: The high-pressure discharge line (9) is connected to the exhaust gas discharge line (11), and the output end of the exhaust gas discharge line (11) is respectively connected to the flare combustion line (13) and the tail gas recovery line (14), and the tail gas recovery line (14) sends the tail gas to the combustible gas recovery line (19) through the transfer tank (15).

2. A deethanizer tail gas efficient recovery system according to claim 1, characterized in that: A pressure relief valve is installed on the flare combustion line (13). When the pressure in the transfer tank (15) is excessive, the pressure relief valve opens to send the combustible gas to the flare for combustion through the flare combustion line (13).

3. A deethanizer tail gas efficient recovery system according to claim 1 or 2, characterized in that: A distributor (16) is also provided in the transfer tank (15), the tail gas recovery line (14) is connected to the distributor (16), a sprayer (20) is installed in the transfer tank (15), and the bottom of the transfer tank (15) is connected to a water outlet pipeline (17) for discharging spray water.

4. A deethanizer tail gas efficient recovery system according to claim 1, characterized in that: The atmospheric pressure discharge line (4) is connected to the condenser (5), the condenser (5) is connected to the reflux tank (7), and the reflux tank (7) returns the recoverable liquid to the deethanizer (1) through the reflux pipeline (8).

5. A deethanizer tail gas efficient recovery system according to claim 4, characterized in that: The condenser (5) is provided with a medium heat exchange pipeline (6), and the input end of the medium heat exchange pipeline (6) is connected to the medium delivery pipeline (18).

6. A deethanizer tail gas efficient recovery system according to claim 1, characterized in that: A pressure control valve (10) is installed on the high-pressure discharge line (9). When the atmospheric pressure discharge line (4) normally transports the tail gas but the deethanizer (1) is still at high pressure, the pressure control valve (10) opens and the tail gas is discharged through the high-pressure discharge line (9).

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