Ethylene gas phase recovery device for olefin separation process

Abstract

The utility model discloses an ethylene gas-phase recovery device for an olefin separation process, and belongs to the technical field of olefin separation devices. The device consists of a front valve, a one-way valve, a drainage valve, a blind plate and a rear valve which are sequentially connected between an unqualified ethylene vaporizer and a first-section suction tank of a compressor through pipelines, so as to realize the function of material isolation. When an ethylene spherical tank used for storing ethylene is inspected, an unqualified ethylene vaporizer is used for releasing high-pressure ethylene gas (1.65 MPa) to a water washing tower (0.7 MPa) through a valve to be recycled; when the pressure of the ethylene spherical tank is reduced to be close to the pressure of the water washing tower, ethylene gas in the ethylene spherical tank is released to the first-section suction tank (0.05 MPa) of the compressor through the ethylene gas phase recovery device disclosed by the utility model, and then enters the water washing tower through first-section and second-section compression, so that the ethylene is recovered to the maximum extent, and the recovery efficiency of the ethylene gas phase is improved. The waste of materials and the pollution to the environment are reduced, and the economic loss caused by inspection is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of olefin separation devices, and specifically relates to an ethylene gas phase recovery device for olefin separation process. The recovery device recovers ethylene required for processing during the inspection of ethylene spherical tanks as much as possible through newly added valves and pipelines, thereby minimizing material waste and reducing economic losses caused by the inspection. Background Art

[0002] The methanol to olefins unit (MTO unit for short) includes units such as reaction, olefin separation and intermediate tank area. The olefin separation unit receives the reaction gas from the reaction unit and the C2 and C3 components generated by the recycling of C4 into the olefin separation process. After compression, acid gas removal, washing and drying, it enters the depropanizer for separation. The top stream of the depropanizer is sent to the demethanizer after four-stage compression of the reaction gas. The top product of the demethanizer is mainly methane hydrogen, which is sent to the fuel gas pipeline network after passing through the cold box; the bottom stream of the depropanizer is sent to the dehexene tower to obtain C7 plus products and circulating C4 to C6 mixtures. The bottom stream of the demethanizer is sent to the deethanizer to separate the C2 mixture and the C3 mixture. The C2 mixture at the top of the deethanizer passes through the acetylene converter and enters the ethylene distillation tower. After distillation and separation in the ethylene distillation tower, the ethylene product is obtained at the top of the tower. The C3 mixture at the bottom of the deethanizer enters the propylene distillation tower. After distillation and separation in the 1#&2# propylene distillation tower, the propylene product is obtained at the top of the tower. The ethylene and propylene products are respectively sent to the intermediate tank area unit, and then to the downstream polypropylene unit, propylene oxide and styrene co-production unit, vinyl chloride unit, etc.

[0003] The intermediate tank area unit is mainly responsible for the storage and transfer of materials. It is a production auxiliary unit and does not directly participate in product production. It is used to store ethylene, propylene, propane, mixed C4 products, mixed pentene products, C7 plus products delivered from the olefin separation unit, methanol-containing wastewater from the reaction unit, by-product gasoline, and start-up diesel and other media.

[0004] When the ethylene spherical tank is inspected, the ethylene to be treated can only enter the water washing tower of the separation unit (such as Figure 1 As shown); the operating pressure of the water scrubber is 0.7Mpa, so when processing the ethylene in the ethylene spherical tank, when the pressure drops to 0.7Mpa, it can no longer be recovered through the water scrubber and can only be discharged through the flare system, resulting in material waste and environmental pollution. Utility Model Content

[0005] The utility model aims to provide an ethylene gas phase recovery device for olefin separation process, which is composed of a front valve, a one-way valve, a drain valve, a blind plate and a rear valve which are sequentially connected between a failed ethylene vaporizer and a first suction tank of a compressor by pipelines to realize the function of isolating materials.

[0006] During the inspection of the ethylene spherical tank, an unqualified ethylene vaporizer is used to release the high-pressure ethylene gas (1.65MPa) to the water scrubber (0.7MPa) for recovery through a valve. When the pressure of the ethylene spherical tank is reduced to a pressure close to that of the water scrubber (0.7MPa), the ethylene gas in the ethylene spherical tank is released to the first suction tank of the compressor (0.05MPa) through the ethylene gas phase recovery device of the utility model, and then enters the water scrubber after first and second stage compression, thereby recovering ethylene to the maximum extent and reducing material waste and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 : It is a schematic diagram of the structure of the ethylene spherical tank gas phase recovery device in the prior art;

[0008] Figure 2 : It is a schematic structural diagram of the ethylene spherical tank gas phase recovery device of the present invention;

[0009] Names of each part: Valve 1 from the unqualified ethylene vaporizer 7 to the water washing tower 9, front valve 2 from the unqualified ethylene vaporizer 7 to the compressor first-stage suction tank 8, rear valve 3, shower valve 4, one-way valve 5, blind plate 6. DETAILED DESCRIPTION

[0010] Example 1

[0011] During normal ethylene spherical tank inspection, the liquid phase in the ethylene spherical tank to be inspected is emptied first. After the liquid phase is emptied, the remaining 1.7MPa of gaseous ethylene is recovered through the water washing tower via valve 1, so that the pressure of the ethylene spherical tank is reduced to 0.7MPa. The remaining 0.7MPa of gaseous ethylene in the ethylene spherical tank can only be discharged by flaring. The ethylene gas phase recovery device described in the utility model can recover the remaining 0.7MPa of gaseous ethylene in the ethylene spherical tank. When the pressure of the ethylene spherical tank is reduced to the same pressure as the first suction tank 8 of the reaction gas compressor (about 0.05MPa), the recovery is completed, and the remaining ethylene in the ethylene spherical tank is discharged by flaring; thereby, the waste of materials can be minimized and the economic losses caused by inspection can be reduced.

[0012] First, before the ethylene spherical tank needs to be inspected, the blind plate 6 from the unqualified ethylene vaporizer 7 to the compressor suction tank 8 is changed from the "blind plate to the orifice plate" state (i.e., from the isolation state to the non-isolation state), the front valve 2, the rear valve 3 and the drainage valve 4 are in the closed state, and the valve 1 is also in the closed state; then when the ethylene spherical tank needs to be inspected, the valve 1 is fully opened, and the states of the other valves remain unchanged, and the unqualified ethylene vaporizer 7 is used to release 1.65MPa of ethylene gas to the water scrubber 9 for recovery. When the pressure of the ethylene spherical tank is reduced to a pressure close to that of the water scrubber 9 (0.7MPa), the valve 1 is closed. Confirm that the drain valve 4 is in the closed state, fully open the front valve 2, slowly open the rear valve 3, adjust the opening of the valve 3 according to the pressure of the compressor first suction tank 8 and the MTO reaction feed rate at that time, and slowly release the remaining ethylene gas in the ethylene spherical tank into the product gas compressor first suction tank 8, and then enter the water scrubber 9 after one or two stages of compression, and treat it together with the reaction gas from the reaction unit to maximize recovery (the main function of the water scrubber 9 is to wash the oxides in the reaction gas from the reaction unit. The recovery through the water scrubber 9 is mainly because the pressure of the water scrubber is relatively low compared to the entire process, and a large amount of recovery can be achieved. The water scrubber 9 mainly treats the oxides in the reaction gas, and the treated gas phase is sent to the alkali scrubber after being discharged from the top of the water scrubber 9, and the treated wastewater is sent back to the reaction unit after being discharged from the bottom of the water scrubber 9); finally, when the pressure of the ethylene spherical tank drops to 0.05MPa, close the front valve 2 and the rear valve 3, open the drain valve 4 to empty and treat the gas phase ethylene remaining at the blind plate. When the blind plate is ready for plugging, the blind plate is turned from the orifice plate back to the blind plate state, and the gas phase ethylene recovery of the ethylene spherical tank is now completed.

[0013] The device specifications used in the present invention are as follows: the front valve 2 is a DN100, CL300 gate valve, the rear valve 3 is a DN100, CL300 gate valve, the shower valve 4 is a DN20, CL300 gate valve, the check valve 5 is a DN100, CL300 check valve, the blind plate 6 is a DN100, CL300 model 8-shaped blind plate, the pipeline is a DN100 material A333Gr6 low-temperature pipe, the pressure of the compressor first suction tank 8 is 0.05Mpa, and the pressure of the water washing tower 9 is 0.7Mpa.

Claims

1. An ethylene gas phase recovery device for an olefin separation process, characterized in that: The invention is composed of a front valve (2), a check valve (5), a drain valve (4), a blind plate (6) and a rear valve (3) which are connected in sequence between a failed ethylene vaporizer (7) and a first suction tank (8) of a compressor.

2. The ethylene gas phase recovery device for olefin separation process according to claim 1, characterized in that: The front valve (2) is a DN100, CL300 gate valve, the rear valve (3) is a DN100, CL300 gate valve, the drain valve (4) is a DN20, CL300 gate valve, the check valve (5) is a DN100, CL300 check valve, the blind plate (6) is a DN100, CL300 model 8-shaped blind plate, and the pipeline is a DN100 material A333Gr6 low-temperature pipe.

Images