CN215947197U - Hydrocarbon recovery system in tail gas - Google Patents
Hydrocarbon recovery system in tail gas Download PDFInfo
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- CN215947197U CN215947197U CN202121445908.5U CN202121445908U CN215947197U CN 215947197 U CN215947197 U CN 215947197U CN 202121445908 U CN202121445908 U CN 202121445908U CN 215947197 U CN215947197 U CN 215947197U
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Abstract
The utility model belongs to the technical field of waste gas recovery, and relates to a hydrocarbon recovery system in tail gas, which comprises a buffer tank, wherein the inlet of the buffer tank is communicated with a gas phase outlet of a high-pressure liquid separation tank, and the inlet of a first heater is communicated with the outlet of the buffer tank; a plurality of groups of circulating pipes are arranged in the cold box, and the inlet of the first group of circulating pipes is communicated with the outlet of the first heater; the inlet of the first gas-liquid separation tank is communicated with the outlet of the first group of circulating pipes, the liquid phase outlet is communicated with the reactor, and the gas phase outlet is communicated with the inlet of the second group of circulating pipes; the inlet of the second gas-liquid separation tank is communicated with the outlet of the second group of circulating pipes, the outlet of the second gas-liquid separation tank is communicated with the olefin separation device, and the gas phase outlet of the second gas-liquid separation tank is communicated with the inlet of the third group of circulating pipes; the inlet of the expansion unit is communicated with the outlet of the third group of circulating pipes, the outlet of the expansion unit is communicated with the inlet of the fourth group of circulating pipes, and the outlet of the fourth group of circulating pipes is communicated with the torch. The utility model has simple flow structure, convenient operation, no consumption of other public works and strong practicability.
Description
Technical Field
The utility model belongs to the technical field of waste gas recovery, and particularly relates to a system for recovering hydrocarbons in tail gas.
Background
In the existing gas-phase polyethylene process, a discharged gas recovery system adopts a traditional compression/condensation process, all ethylene, 1-butene and isopentane in tail gas cannot be condensed, and the tail gas still contains a small amount of hydrocarbon components and is discharged to a torch, so that not only is the waste of materials caused, but also the environment is polluted to a certain extent after the tail gas is burned by the torch.
The existing similar device adopts a membrane permeation technology to recover ethylene, 1-butene and isopentane in tail gas, and due to the limitation of the membrane technology, the recovery rate is lower than 80%, the occupied area is large, the process operation process uses movable equipment, the membrane is frequently replaced, the maintenance cost is high, and the consumption of public works is high.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present invention provides a system for recovering hydrocarbons from tail gas, so as to solve the above-mentioned technical problems.
The technical scheme of the utility model is as follows:
a system for recovering hydrocarbons from a tail gas, comprising:
the inlet of the buffer tank is communicated with the gas phase outlet of the high-pressure liquid separation tank;
a first heater, an inlet of which is communicated with an outlet of the buffer tank;
the cold box is internally provided with a plurality of groups of circulating pipes, and the inlet of the first group of circulating pipes is communicated with the outlet of the first heater;
the inlet of the first gas-liquid separation tank is communicated with the outlet of the first group of circulating pipes, the liquid phase outlet of the first gas-liquid separation tank is communicated with the reactor, and the gas phase outlet of the first gas-liquid separation tank is communicated with the inlet of the second group of circulating pipes;
the inlet of the second gas-liquid separation tank is communicated with the outlet of the second group of circulating pipes, the liquid phase outlet of the second gas-liquid separation tank is communicated with the olefin separation device, and the gas phase outlet of the second gas-liquid separation tank is communicated with the inlet of the third group of circulating pipes;
and the inlet of the expansion unit is communicated with the outlet of the third group of circulating pipes, the outlet of the expansion unit is communicated with the inlet of the fourth group of circulating pipes, and the outlet of the fourth group of circulating pipes is communicated with a torch.
Preferably, the expansion unit comprises a first expander and a second expander, the inlet of the first expander is communicated with the outlet of the third group of circulation pipes, the outlet of the first expander is communicated with the inlet of the fifth group of circulation pipes, the outlet of the fifth group of circulation pipes is communicated with the inlet of the second expander, and the outlet of the second expander is communicated with the inlet of the fourth group of circulation pipes.
Preferably, a second heater for heating is arranged between the liquid phase outlet of the first gas-liquid separation tank and the reactor, and a third heater for heating is arranged between the liquid phase outlet of the second gas-liquid separation tank and the olefin separation device.
Preferably, the first heater, the second heater and the third heater are all electric heaters.
The hydrocarbon recovery system in the tail gas provided by the utility model uses a double-expansion self-cryogenic technology, reduces the temperature to-120 ℃ by using the pressure energy of the flare gas, liquefies almost all hydrocarbons in the flare gas and then separates the hydrocarbons from nitrogen, thereby realizing the recovery of the hydrocarbons, achieving the recovery rate of more than 90%, reducing the production cost and reducing the discharge of VOCs. The technology has no rotating equipment, low maintenance cost, simple flow structure and convenient operation, and only needs to consume 20Nm3The nitrogen gas of about/h has no consumption of other public works, has strong practicability and is worth popularizing.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
Detailed Description
The utility model provides a system for recovering hydrocarbons in tail gas, which is described below by referring to a schematic structural diagram of fig. 1.
Example 1
A recovery system for hydrocarbons in tail gas adopts a cryogenic separation system, and structurally comprises a buffer tank for providing a decompression buffer storage effect, wherein an inlet of the buffer tank is communicated with a gas phase outlet of a high-pressure liquid separation tank of the recovery system, the recovered tail gas comes out through the gas phase outlet and enters the buffer tank for internal storage, an outlet of the buffer tank is communicated with an inlet of a first heater, and the recovered tail gas enters the first heater through the buffer tank and is heated through the first heater.
The cooling box is internally provided with a plurality of groups of circulating pipes for circulating cooling, the outlet of the first heater is communicated with the inlet of the first group of circulating pipes, the outlet of the first group of circulating pipes is communicated with the inlet of the first gas-liquid separation tank, the liquid phase outlet of the first gas-liquid separation tank is communicated with the reactor, the gas phase outlet of the first gas-liquid separation tank is communicated with the inlet of the second group of circulating pipes, the outlet of the second group of circulating pipes is communicated with the inlet of the second gas-liquid separation tank, the liquid phase outlet of the second gas-liquid separation tank is communicated with the olefin separation device, the gas phase outlet of the second gas-liquid separation tank is communicated with the inlet of the third group of circulating pipes, the outlet of the third group of circulating pipes is communicated with the inlet of the expansion unit, the outlet of the expansion unit is communicated with the inlet of the fourth group of circulating pipes, and the outlet of the fourth group of circulating pipes is communicated with the torch.
More specifically, the expansion unit comprises a first expansion machine and a second expansion machine, wherein the inlet of the first expansion machine is communicated with the outlet of the third group of circulating pipes, the outlet of the first expansion machine is communicated with the inlet of the fifth group of circulating pipes, the outlet of the fifth group of circulating pipes is communicated with the inlet of the second expansion machine, and the outlet of the second expansion machine is communicated with the inlet of the fourth group of circulating pipes.
Further, a second heater for heating the liquid phase is arranged between the liquid phase outlet of the first gas-liquid separation tank and the reactor, and a third heater for heating the liquid phase is arranged between the liquid phase outlet of the second gas-liquid separation tank and the olefin separation device.
Specifically, the first heater, the second heater and the third heater are all electric heaters.
The utility model provides a system for recovering hydrocarbons in tail gas, which specifically comprises a cold box, a turbo expander (comprising a first expander and a second expander), a gas-liquid separation tank (comprising a second gas-liquid separation tank and a first gas-liquid separation tank) and a plurality of heaters, wherein the second gas-liquid separation tank is an ethylene separator and is used for separating gas-liquid ethylene, and the first gas-liquid separation tank is a heavy hydrocarbon separator and is used for separating gas-liquid heavy hydrocarbon.
When the device works, the recovered tail gas firstly enters the buffer tank, then enters the first heater through the buffer tank, enters the cold box after being heated to 40 ℃ by the first heater, is cooled to minus 50 ℃ by the cold box, and then enters the first gas-liquid separation tank for separating heavy hydrocarbon (1-butylene and isopentane) and ethylene; heating the heavy liquid hydrocarbon from the first gas-liquid separation tank by a second heater (30 ℃, 0.05MPa, mainly about 80 percent of 1-butene and isopentane and about 20 percent of ethylene) and returning the heavy liquid hydrocarbon to the reactor; cooling the gas-phase heavy hydrocarbon from the first gas-liquid separation tank to-120 ℃ through a cooling box, then feeding the gas-phase heavy hydrocarbon into a second gas-liquid separation tank, and returning liquid-phase ethylene (30 ℃, 0.2MPa, about 90% of ethylene and ethane, and about 10% of 1-butene and isopentane) to a first-section inlet of a compressor of an olefin separation device (MTO) after the liquid-phase ethylene is heated by a third heater; the non-condensable gas from the second gas-liquid separation tank enters the expansion end of the first expander for expansion refrigeration, the expanded low-temperature gas returns to the cold box for reheating and cold energy recovery, and then enters the braking end of the second expander for heating and then leaves a cryogenic separation system (30 ℃, 0.2MPa, mainly over 97 percent of nitrogen, and the balance of hydrogen, methane and ethylene) to be discharged out of a torch.
The recovery system for hydrocarbons in tail gas provided by the utility model uses a double-expansion self-cryogenic technology, reduces the temperature of the flare gas to-120 ℃ by using the pressure energy of the flare gas, liquefies almost all hydrocarbons in the flare gas and then separates the hydrocarbons from nitrogen, thereby realizing the recovery of the hydrocarbons and the nitrogen, achieving the recovery rate of more than 90%, reducing the production cost and reducing the discharge of VOCs. The technology has no rotating equipment, low maintenance cost, simple flow structure and convenient operation, and only needs to consume 20Nm3The nitrogen gas of about/h has no consumption of other public works, has strong practicability and is worth popularizing.
The above disclosure is only for the preferred embodiments of the present invention, but the embodiments of the present invention are not limited thereto, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present invention.
Claims (4)
1. A system for recovering hydrocarbons from a tail gas, comprising:
the inlet of the buffer tank is communicated with the gas phase outlet of the high-pressure liquid separation tank;
a first heater, an inlet of which is communicated with an outlet of the buffer tank;
the cold box is internally provided with a plurality of groups of circulating pipes, and the inlet of the first group of circulating pipes is communicated with the outlet of the first heater;
the inlet of the first gas-liquid separation tank is communicated with the outlet of the first group of circulating pipes, the liquid phase outlet of the first gas-liquid separation tank is communicated with the reactor, and the gas phase outlet of the first gas-liquid separation tank is communicated with the inlet of the second group of circulating pipes;
the inlet of the second gas-liquid separation tank is communicated with the outlet of the second group of circulating pipes, the liquid phase outlet of the second gas-liquid separation tank is communicated with the olefin separation device, and the gas phase outlet of the second gas-liquid separation tank is communicated with the inlet of the third group of circulating pipes;
and the inlet of the expansion unit is communicated with the outlet of the third group of circulating pipes, the outlet of the expansion unit is communicated with the inlet of the fourth group of circulating pipes, and the outlet of the fourth group of circulating pipes is communicated with a torch.
2. The system of claim 1, wherein the expansion unit comprises a first expander and a second expander, the inlet of the first expander is communicated with the outlet of the third set of circulation pipes, the outlet of the first expander is communicated with the inlet of a fifth set of circulation pipes, the outlet of the fifth set of circulation pipes is communicated with the inlet of the second expander, and the outlet of the second expander is communicated with the inlet of a fourth set of circulation pipes.
3. The system for recovering hydrocarbons in tail gas according to claim 1, wherein a second heater for raising the temperature is arranged between the liquid phase outlet of the first gas-liquid separation tank and the reactor, and a third heater for raising the temperature is arranged between the liquid phase outlet of the second gas-liquid separation tank and the olefin separation device.
4. The system of claim 3, wherein the first heater, the second heater, and the third heater are electric heaters.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121445908.5U CN215947197U (en) | 2021-06-28 | 2021-06-28 | Hydrocarbon recovery system in tail gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121445908.5U CN215947197U (en) | 2021-06-28 | 2021-06-28 | Hydrocarbon recovery system in tail gas |
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| Publication Number | Publication Date |
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| CN215947197U true CN215947197U (en) | 2022-03-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202121445908.5U Active CN215947197U (en) | 2021-06-28 | 2021-06-28 | Hydrocarbon recovery system in tail gas |
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| CN (1) | CN215947197U (en) |
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2021
- 2021-06-28 CN CN202121445908.5U patent/CN215947197U/en active Active
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