Improved depropanization device

Abstract

The utility model provides an improved depropanization device. Comprising a high-pressure depropanizing tower, a feeding and discharging heat exchanger of the high-pressure depropanizing tower, a centrifugal compressor, a C2 hydrogenation reactor, a high-pressure depropanizing tower return tank, a low-pressure depropanizing tower, a low-pressure depropanizing tower condenser, a low-pressure depropanizing tower return tank, a low-pressure depropanizing tower return pump, a low-pressure depropanizing tower return regulating valve and a propylene liquid supplementing pipeline, the propylene liquid supplementing pipeline is combined with an outlet pipeline of a reflux tank of the high-pressure depropanizing tower and then connected with a tower top inlet pipeline of the high-pressure depropanizing tower; and external propylene is introduced to a reflux line of the high-pressure depropanizing tower through starting, so that the starting time is greatly shortened.

Description

Technical Field

[0001] The utility model belongs to the technical field of depropanization system, in particular to an improved depropanization device. Background Art

[0002] The ethylene plant adopts the pre-depropanization and pre-hydrogenation process technology developed by SW patents. The commissioning and qualification time of the acetylene reactor plays an important role in the qualification of the overall system products. During the start-up and feeding process of the ethylene plant, the C4 content at the top of the high-pressure depropanizer needs to be lower than 500-1000ppm before feeding to the C2 hydrogenation reactor. The original system takes a long time for the C4 at the top of the high-pressure depropanizer to reach the standard, which affects the start-up time of the overall ethylene plant. Utility Model Content

[0003] In view of the above problems, the purpose of this application is to accelerate the qualified time of the tower top by making sufficient propylene liquid at the initial start-up, and shorten the qualified time of C4 at the top of the high-pressure depropanizer tower by about 2 hours, thereby shortening the start-up time of the entire ethylene unit.

[0004] To achieve some or all of the above-mentioned purposes or other purposes, the present application provides the following technical solutions: an improved depropanizer, comprising a high-pressure depropanizer, an inlet and outlet heat exchanger of the high-pressure depropanizer, a centrifugal compressor, a carbon two hydrogenation reactor, a high-pressure depropanizer reflux tank, a low-pressure depropanizer, a low-pressure depropanizer condenser, a low-pressure depropanizer reflux tank, a low-pressure depropanizer reflux pump, and a low-pressure depropanizer reflux regulating valve; the top outlet pipeline of the high-pressure depropanizer is connected to the inlet pipeline of the inlet and outlet heat exchanger of the high-pressure depropanizer, the outlet pipeline of the inlet and outlet heat exchanger of the high-pressure depropanizer is connected to the inlet pipeline of the centrifugal compressor, the outlet pipeline of the centrifugal compressor is connected to the inlet pipeline of the carbon two hydrogenation reactor, the outlet pipeline of the carbon two hydrogenation reactor is connected to the inlet pipeline of the high-pressure depropanizer reflux tank, and the high-pressure depropanizer is connected to the inlet pipeline of the high-pressure depropanizer. The reflux tank outlet pipeline is connected to the high-pressure depropanizer tower top inlet pipeline; the high-pressure depropanizer tower top inlet pipeline is provided with a first regulating valve; the low-pressure depropanizer tower top outlet pipeline is connected to the low-pressure depropanizer tower condenser inlet pipeline, the low-pressure depropanizer tower condenser outlet pipeline is connected to the low-pressure depropanizer tower reflux tank inlet pipeline, the low-pressure depropanizer tower reflux tank outlet pipeline is connected to the low-pressure depropanizer tower reflux pump inlet pipeline, the low-pressure depropanizer tower reflux pump outlet pipeline is connected to three pipelines, namely, the low-pressure depropanizer tower reflux regulating valve inlet pipeline, the propylene liquid supplement pipeline, and the propylene distillation tower inlet pipeline, the low-pressure depropanizer tower reflux regulating valve outlet pipeline is connected to the low-pressure depropanizer tower top inlet pipeline; the propylene liquid supplement pipeline is connected to the high-pressure depropanizer tower top inlet pipeline after being combined with the high-pressure depropanizer tower reflux tank outlet pipeline.

[0005] Furthermore, at the initial stage of operation, the low-pressure depropanizer reflux pump is a variable frequency pump.

[0006] Furthermore, a second regulating valve is provided on the propylene liquid replenishment pipeline.

[0007] Furthermore, at the initial start-up stage, the first regulating valve and the second regulating valve are in an open valve state.

[0008] Compared with the prior art, the utility model has the following beneficial effects: a pipeline is led out from the outlet of the reflux pump of the low-pressure depropanizer to the reflux line of the high-pressure depropanizer, and the propylene liquid produced by the low-pressure depropanizer system accelerates the qualified time of C4 at the top of the high-pressure depropanizer. The qualified time of C4 at the top of the high-pressure depropanizer is shortened by about 2 hours through this pipeline, thereby shortening the start-up time of the entire ethylene unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the utility model.

[0010] In the figure: 1. high-pressure depropanizer, 2. inlet and outlet heat exchanger of high-pressure depropanizer, 3. centrifugal compressor, 4. carbon two hydrogenation reactor, 5. high-pressure depropanizer reflux tank, 6. low-pressure depropanizer, 7. low-pressure depropanizer condenser, 8. low-pressure depropanizer reflux tank, 9. low-pressure depropanizer reflux pump, 10. low-pressure depropanizer reflux regulating valve, 11. propylene liquid feed pipeline, 12. propylene distillation tower, 13. first regulating valve, 14. second regulating valve. DETAILED DESCRIPTION

[0011] In order to make the structure and function of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0012] See attached Figure 1, an improved depropanizer, comprising a high-pressure depropanizer 1, an inlet and outlet heat exchanger 2 of the high-pressure depropanizer, a centrifugal compressor 3, a carbon two hydrogenation reactor 4, a high-pressure depropanizer reflux tank 5, a low-pressure depropanizer 6, a low-pressure depropanizer condenser 7, a low-pressure depropanizer reflux tank 8, a low-pressure depropanizer reflux pump 9, and a low-pressure depropanizer reflux regulating valve 10; the top outlet pipeline of the high-pressure depropanizer 1 is connected to the inlet pipeline of the inlet and outlet heat exchanger 2 of the high-pressure depropanizer, the outlet pipeline of the inlet and outlet heat exchanger 2 of the high-pressure depropanizer is connected to the inlet pipeline of the centrifugal compressor 3, the outlet pipeline of the centrifugal compressor 3 is connected to the inlet pipeline of the carbon two hydrogenation reactor 4, the outlet pipeline of the carbon two hydrogenation reactor 4 is connected to the inlet pipeline of the high-pressure depropanizer reflux tank 5, and the outlet pipeline of the high-pressure depropanizer reflux tank 5 is connected to the high-pressure depropanizer 1 top inlet pipeline; a first regulating valve 13 is arranged on the top inlet pipeline of the high-pressure depropanizer 1; the top outlet pipeline of the low-pressure depropanizer 6 is connected to the inlet pipeline of the low-pressure depropanizer condenser 7, the outlet pipeline of the low-pressure depropanizer condenser 7 is connected to the inlet pipeline of the low-pressure depropanizer reflux tank 8, the outlet pipeline of the low-pressure depropanizer reflux tank 8 is connected to the inlet pipeline of the low-pressure depropanizer reflux pump 9, the outlet pipeline of the low-pressure depropanizer reflux pump 9 is connected to three pipelines, namely, the inlet pipeline of the low-pressure depropanizer reflux regulating valve 10, the propylene liquid supplement pipeline 11, and the inlet pipeline of the propylene distillation tower 12, the outlet pipeline of the low-pressure depropanizer reflux regulating valve 10 is connected to the top inlet pipeline of the low-pressure depropanizer 6; the propylene liquid supplement pipeline 11 is combined with the outlet pipeline of the high-pressure depropanizer reflux tank 5 and then connected to the top inlet pipeline of the high-pressure depropanizer 1.

[0013] Furthermore, at the initial stage of operation, the low-pressure depropanizer reflux pump 9 is a variable frequency pump.

[0014] Furthermore, a second regulating valve 14 is provided on the propylene liquid supplement pipeline 11 .

[0015] Furthermore, at the initial stage of start-up, the first regulating valve 13 and the second regulating valve 14 are in the open valve state; the operating pressure of the high-pressure depropanizer reflux tank 5 is too high (3.3-3.4MpaG), and the normal propylene replenishing process is to replenish propylene from outside the boundary into the lower part of the high-pressure depropanizer reflux tank 5, with a pressure of about 3.6 MpaG and a head of 380m. Due to the small pressure difference, the replenishment amount during the start-up period is insufficient. A newly designed low-pressure depropanizer reflux pump 9 outlet pipeline is connected to the high-pressure depropanizer reflux tank 5 outlet pipeline through the propylene replenishment liquid pipeline 11. The pressure difference between the front and the back is large. When the valve is fully opened, the replenishment amount can be guaranteed, the early self-circulation state of the depropanizer is established, and the start-up time is shortened.

[0016] Furthermore, the high-pressure depropanizer 1 is operated at a pressure of 1.459 MpaG, and the low-pressure depropanizer 6 is operated at a pressure of 0.709 MpaG, which can alleviate the coking problem existing in a single tower system.

[0017] Furthermore, when the propylene liquid is initially started, it is led back from the off-site propylene spherical tank to the propylene distillation tower, and then sent to the low-pressure depropanizer through the propylene distillation tower kettle process.

[0018] The above examples are only the best embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and there are many variations. All variations that can be directly derived or associated with the contents disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. An improved depropanizer, comprising a high-pressure depropanizer (1), an inlet and outlet heat exchanger (2) of the high-pressure depropanizer, a centrifugal compressor (3), a carbon two hydrogenation reactor (4), a high-pressure depropanizer reflux tank (5), a low-pressure depropanizer (6), a low-pressure depropanizer condenser (7), a low-pressure depropanizer reflux tank (8), a low-pressure depropanizer reflux pump (9), and a low-pressure depropanizer reflux regulating valve (10); characterized in that: The outlet pipeline at the top of the high-pressure depropanizer (1) is connected to the inlet pipeline of the inlet and outlet heat exchanger (2) of the high-pressure depropanizer, the outlet pipeline of the inlet and outlet heat exchanger (2) of the high-pressure depropanizer is connected to the inlet pipeline of the centrifugal compressor (3), the outlet pipeline of the centrifugal compressor (3) is connected to the inlet pipeline of the carbon two hydrogenation reactor (4), the outlet pipeline of the carbon two hydrogenation reactor (4) is connected to the inlet pipeline of the high-pressure depropanizer reflux tank (5), the outlet pipeline of the high-pressure depropanizer reflux tank (5) is connected to the inlet pipeline at the top of the high-pressure depropanizer (1); a first regulating valve (13) is arranged on the inlet pipeline at the top of the high-pressure depropanizer (1); the outlet pipeline at the top of the low-pressure depropanizer (6) is connected to the condenser (7) of the low-pressure depropanizer The outlet pipeline of the low-pressure depropanizer condenser (7) is connected to the inlet pipeline of the low-pressure depropanizer reflux tank (8), the outlet pipeline of the low-pressure depropanizer reflux tank (8) is connected to the inlet pipeline of the low-pressure depropanizer reflux pump (9), the outlet pipeline of the low-pressure depropanizer reflux pump (9) is connected to three pipelines, namely, the inlet pipeline of the low-pressure depropanizer reflux regulating valve (10), the propylene liquid supplement pipeline (11), and the inlet pipeline of the propylene distillation tower (12), the outlet pipeline of the low-pressure depropanizer reflux regulating valve (10) is connected to the inlet pipeline of the top of the low-pressure depropanizer (6); the propylene liquid supplement pipeline (11) is combined with the outlet pipeline of the high-pressure depropanizer reflux tank (5) and then connected to the inlet pipeline of the top of the high-pressure depropanizer (1).

2. An improved depropanizer according to claim 1, characterized in that: At the beginning of the operation, the low-pressure depropanizer reflux pump (9) is a variable frequency pump.

3. An improved depropanizer according to claim 1, characterized in that: A second regulating valve (14) is provided on the propylene liquid replenishment pipeline (11).

4. An improved depropanizer according to claim 3, characterized in that: At the beginning of operation, the first regulating valve (13) and the second regulating valve (14) are in an open valve state.

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