Slurry method polyethylene tail gas recovery system

Abstract

The utility model discloses a slurry method polyethylene tail gas recovery system which comprises a first heat exchanger and a second heat exchanger, the first rectifying tower is connected with the first heat exchanger through a pipeline; a liquid phase outlet of the second rectifying tower is connected with the ethylene output pipe, and a gas phase outlet of the second rectifying tower is connected with the gas phase discharge pipe; the first separator is connected with the first heat exchanger through a pipeline, a gas phase outlet of the first separator is connected with the second separator through a first pipeline, the first pipeline passes through the second heat exchanger, and a gas phase outlet of the second separator is connected with a gas phase inlet of the expansion machine through a second pipeline; a gas phase outlet of the expansion machine is connected with a nitrogen output pipe, and a liquid phase outlet of the second separator is connected with a mixed hydrocarbon output pipe through a pipeline. The tail gas recovery device has the advantages that the discharged tail gas can be separated and recovered, the environmental pollution is avoided, the utilization value of the tail gas is improved, and the production benefit is increased.

Description

Technical Field

[0001] The utility model relates to a gas recovery device, in particular to a slurry process polyethylene tail gas recovery system. Background Art

[0002] High-density polyethylene (HDPE), as a thermoplastic resin with good mechanical and processing properties, is an indispensable and important material in many aspects such as industry, agriculture, and life.

[0003] The slurry process was industrialized earlier to produce polyethylene and is the main method for producing high-density polyethylene. The characteristic of this method is that the polymer generated by the reaction is suspended in a diluent.

[0004] The high-density polyethylene slurry process uses high-purity ethylene as the main raw material, propylene as the comonomer, and hexane as the solvent, and performs low-pressure slurry polymerization under the action of a high-efficiency catalyst. After separation and drying, mixing and granulation, particle mixing, packaging and palletizing, the polymerized slurry can obtain various high-density polyethylene products with excellent performance. Various raw material gases are required in the production process, and a large amount of tail gas will also be generated. The tail gas contains a large amount of nitrogen and ethylene gas. If it can be recycled, it will not only help protect the environment but also greatly improve the economic benefits of the enterprise. Utility Model Content

[0005] The utility model aims to provide a slurry process polyethylene tail gas recovery system.

[0006] The utility model of the slurry process polyethylene tail gas recovery system comprises:

[0007] a first heat exchanger for cooling a first feed gas comprising an ethylene component and a second feed gas comprising a nitrogen component;

[0008] A first distillation tower for distilling the first raw gas is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first distillation tower is connected to the liquid phase heavy component output pipe, and the gas phase outlet of the first distillation tower is connected to the gas phase output pipe;

[0009] A second distillation tower for distilling the gas phase is connected to the first distillation tower through a gas phase output pipe, the liquid phase outlet of the second distillation tower is connected to the ethylene output pipe, the gas phase outlet of the second distillation tower is connected to the gas phase discharge pipe, and the gas phase output pipe passes through a second heat exchanger;

[0010] The first separator for separating the second raw gas into gas and liquid is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first separator is connected to the first heat exchanger through a first pipeline, the gas phase outlet of the first separator is connected to the second separator through a second pipeline, the second pipeline passes through the second heat exchanger, the gas phase outlet of the second separator is connected to the gas phase inlet of the expander through a third pipeline, the third pipeline passes through the second heat exchanger, the gas phase outlet of the expander is connected to the nitrogen output pipe, and the liquid phase outlet of the second separator is connected to the mixed hydrocarbon output pipe through a pipeline.

[0011] The utility model discloses a slurry process polyethylene tail gas recovery system, wherein the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

[0012] The utility model of the slurry process polyethylene tail gas recovery system comprises:

[0013] a first heat exchanger for cooling a first feed gas comprising an ethylene component and a second feed gas comprising a nitrogen component;

[0014] a second heat exchanger for further cooling the first raw gas, connected to the first heat exchanger through a pipeline;

[0015] A distillation tower for distilling the first raw gas is connected to the second heat exchanger through a pipeline, the liquid phase outlet of the distillation tower is connected to the ethylene output pipe, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the gas phase outlet of the distillation tower is connected to the gas phase discharge pipe, and the gas phase discharge pipe passes through the second heat exchanger;

[0016] The first separator for separating the second raw gas into gas and liquid is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first separator is connected to the first heat exchanger through a first pipeline, the gas phase outlet of the first separator is connected to the second separator through a second pipeline, the second pipeline passes through the second heat exchanger, the gas phase outlet of the second separator is connected to the gas phase inlet of the expander through a third pipeline, the third pipeline passes through the second heat exchanger, the gas phase outlet of the expander is connected to the nitrogen output pipe, and the liquid phase outlet of the second separator is connected to the mixed hydrocarbon output pipe through a pipeline.

[0017] The utility model discloses a slurry process polyethylene tail gas recovery system, wherein the mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

[0018] The utility model of the slurry process polyethylene tail gas recovery system comprises:

[0019] a first heat exchanger for cooling a first feed gas comprising an ethylene component and a second feed gas comprising a nitrogen component;

[0020] A second heat exchanger for further cooling the first raw gas and the second raw gas, connected to the first heat exchanger through a pipeline;

[0021] A distillation tower for distilling the first raw gas is connected to the second heat exchanger through a pipeline, the liquid phase outlet of the distillation tower is connected to the ethylene output pipe, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the gas phase outlet of the distillation tower is connected to the gas phase discharge pipe, and the gas phase discharge pipe passes through the second heat exchanger;

[0022] A separator for separating the second raw gas into gas and liquid is connected to the second heat exchanger through a pipeline. The gas phase outlet of the separator is connected to the gas phase inlet of the expander through a gas transmission pipeline. The gas transmission pipeline passes through the second heat exchanger. The gas phase outlet of the expander is connected to the nitrogen output pipe. The liquid phase outlet of the separator is connected to the mixed hydrocarbon output pipe through a pipeline. The mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence. The nitrogen output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

[0023] The utility model has the advantages that the discharged tail gas can be separated and recovered, thus avoiding environmental pollution, improving the utilization value of the tail gas and increasing production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a first embodiment of a slurry polyethylene tail gas recovery system of the utility model;

[0025] Figure 2 It is a structural schematic diagram of a second embodiment of a slurry polyethylene tail gas recovery system of the utility model;

[0026] Figure 3 It is a structural schematic diagram of the third embodiment of the slurry process polyethylene tail gas recovery system of the utility model. DETAILED DESCRIPTION

[0027] The main equipment of the slurry polyethylene tail gas recovery system of the utility model includes: heat exchanger, distillation tower, booster, separator, expander and related valves and pipelines. The raw gas enters the system, and after cooling, part of the raw gas is liquefied, and after separation by the separator, the corresponding component products can be obtained.

[0028] Embodiment 1

[0029] like Figure 1 As shown, the slurry polyethylene tail gas recovery system of the utility model comprises:

[0030] A first heat exchanger E1 for cooling a first feed gas 1 containing an ethylene component and a second feed gas 2 containing a nitrogen component;

[0031] A first distillation tower V1 for distilling the first raw gas is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first distillation tower is connected to the liquid phase heavy component output pipe 6, and the gas phase outlet of the first distillation tower is connected to the gas phase output pipe 20;

[0032] The second distillation tower V3 for the gas phase distillation is connected to the first distillation tower through the gas phase output pipe 20, the liquid phase outlet of the second distillation tower is connected to the ethylene output pipe 4, the gas phase outlet of the second distillation tower is connected to the gas phase discharge pipe 31, the gas phase output pipe 20 passes through the second heat exchanger E2, and the gas phase discharge pipe 31 passes through the second heat exchanger E2;

[0033] The first separator V2 for separating the second raw gas into gas and liquid is connected to the first heat exchanger through a pipeline. The liquid phase outlet of the first separator is connected to the first heat exchanger through a first pipeline 51, and the gas phase outlet of the first separator is connected to the second separator V4 through a second pipeline 52. The second pipeline 52 passes through the second heat exchanger. The gas phase outlet of the second separator is connected to the gas phase inlet of the expander C2 through a third pipeline 53. The third pipeline 53 passes through the second heat exchanger. The gas phase outlet of the expander is connected to the nitrogen output pipe 5, and the liquid phase outlet of the second separator is connected to the mixed hydrocarbon output pipe 3 through a pipeline.

[0034] In the utility model of the slurry polyethylene tail gas recovery system, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the mixed hydrocarbon output pipe 3 passes through the second heat exchanger and the first heat exchanger in sequence.

[0035] The first pipeline 51 and the gas phase discharge pipe 31 are respectively connected to the mixed hydrocarbon output pipe 3 .

[0036] The working process of the embodiment of the slurry polyethylene tail gas recovery system of the utility model is as follows:

[0037] The first raw gas 1 containing ethylene components enters the first heat exchanger E1 for cooling, and then enters the first distillation tower V1 for separation. The liquid phase heavy component is obtained at the bottom of the tower. The gas phase component at the top of the tower enters the second heat exchanger E2 for cooling, and then enters the second distillation tower V3 for separation. The separated gas phase and a part of the liquid phase enter the second heat exchanger E2 for heat exchange. The remaining liquid phase is reheated by the second heat exchanger E2 and the first heat exchanger E1, and the product gas with ethylene as the main component is output;

[0038] The second raw gas 2 containing nitrogen components enters the first heat exchanger E1 for cooling, and then enters the first separator V2 for separation. The liquid phase heavy component obtained at the bottom of the tower enters the first heat exchanger E1. The gas phase component at the top of the tower enters the second heat exchanger E2 for cooling, and then enters the second separator V4 for separation. The separated gas phase enters the second heat exchanger E2, and then enters the expander C2. Finally, after heat exchange in the second heat exchanger E2 and the first heat exchanger E1, a product gas with nitrogen as the main component is obtained. The remaining liquid phase is reheated in the second heat exchanger E2 and then merged into the pipeline of the first heat exchanger E1, and finally the product of the mixed hydrocarbon component is output.

[0039] Embodiment 2

[0040] like Figure 2 As shown, the slurry polyethylene tail gas recovery system of the utility model comprises:

[0041] A first heat exchanger E1 for cooling a first feed gas 1 containing an ethylene component and a second feed gas 2 containing a nitrogen component;

[0042] A second heat exchanger E2 for further cooling the first raw gas, connected to the first heat exchanger through a pipeline;

[0043] A distillation tower V3 for distilling the first raw gas is connected to the second heat exchanger E2 through a pipeline, the liquid phase outlet of the distillation tower is connected to the ethylene output pipe 4, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the gas phase outlet of the distillation tower is connected to the gas phase discharge pipe 31, and the gas phase discharge pipe 31 passes through the second heat exchanger;

[0044] The first separator V2 for separating the second raw gas 2 into gas and liquid is connected to the first heat exchanger through a pipeline. The liquid phase outlet of the first separator is connected to the first heat exchanger through a first pipeline 51, and the gas phase outlet of the first separator is connected to the second separator V4 through a second pipeline 52. The second pipeline passes through the second heat exchanger, and the gas phase outlet of the second separator is connected to the gas phase inlet of the expander C2 through a third pipeline 53. The third pipeline passes through the second heat exchanger, and the gas phase outlet of the expander is connected to the nitrogen output pipe 5. The liquid phase outlet of the second separator is connected to the mixed hydrocarbon output pipe 3 through a pipeline.

[0045] In the utility model of the slurry process polyethylene tail gas recovery system, the mixed hydrocarbon output pipe 3 passes through the second heat exchanger and the first heat exchanger in sequence.

[0046] The first pipeline 51 and the gas phase discharge pipe 31 are respectively connected to the mixed hydrocarbon output pipe 3 .

[0047] The working process of the embodiment of the slurry polyethylene tail gas recovery system of the utility model is as follows:

[0048] The first raw gas 1 containing the ethylene component enters the first heat exchanger E1 for cooling, then enters the second heat exchanger E2 for cooling, and then enters the distillation tower V3 for separation. The separated gas phase and a part of the liquid phase enter the second heat exchanger E2 for heat exchange. The remaining liquid phase is restored to temperature by the second heat exchanger E2 and the first heat exchanger E1, and then the product gas with ethylene as the main component is output.

[0049] The second raw gas 2 containing nitrogen components enters the first heat exchanger E1 for cooling, and then enters the first separator V2 for separation. The liquid phase heavy component obtained at the bottom of the tower enters the first heat exchanger E1, and the gas phase component at the top of the tower enters the second heat exchanger E2 for cooling, and then enters the second separator V4 for separation. The separated gas phase enters the second heat exchanger E2, and then enters the expander C2. Finally, after heat exchange in the second heat exchangers E2 and E1, a product gas with nitrogen as the main component is obtained. The remaining liquid phase is reheated by the second heat exchanger E2 and then merged into the pipeline of the first heat exchanger E1, and finally the product of the mixed hydrocarbon component is output.

[0050] Embodiment 3

[0051] like Figure 3 As shown, the slurry polyethylene tail gas recovery system of the utility model comprises:

[0052] A first heat exchanger E1 for cooling a first feed gas 1 containing an ethylene component and a second feed gas 2 containing a nitrogen component;

[0053] A second heat exchanger E2 for further cooling the first raw gas and the second raw gas, connected to the first heat exchanger through a pipeline;

[0054] A distillation tower V3 for distilling the first raw gas is connected to the second heat exchanger through a pipeline, the liquid phase outlet of the distillation tower is connected to the ethylene output pipe 4, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the gas phase outlet of the distillation tower is connected to the gas phase discharge pipe 31, and the gas phase discharge pipe 31 passes through the second heat exchanger;

[0055] The separator V4 for separating the gas and liquid of the second raw gas 2 is connected to the second heat exchanger through a pipeline. The gas phase outlet of the separator is connected to the gas phase inlet of the expander through a gas transmission pipeline 60. The gas transmission pipeline passes through the second heat exchanger. The gas phase outlet of the expander is connected to the nitrogen output pipe 5. The liquid phase outlet of the separator is connected to the mixed hydrocarbon output pipe 3 through a pipeline. The mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the nitrogen output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

[0056] The gas phase discharge pipe 31 is connected to the mixed hydrocarbon output pipe 3 .

[0057] The working process of the embodiment of the slurry polyethylene tail gas recovery system of the utility model is as follows:

[0058] The first raw gas 1 containing the ethylene component enters the first heat exchanger E1 for cooling, then enters the second heat exchanger E2 for cooling, and then enters the distillation tower V3 for separation. The separated gas phase and a part of the liquid phase enter the second heat exchanger E2 for heat exchange. The remaining liquid phase is restored to temperature by the second heat exchanger E2 and the first heat exchanger E1, and then the product gas with ethylene as the main component is output.

[0059] The second raw gas 2 containing the nitrogen component enters the first heat exchanger E1 for cooling, then enters the second heat exchanger E2 for cooling, and then enters the separator V4 for separation. The separated gas phase enters the second heat exchanger E2, and then enters the expander C2. Finally, after heat exchange in the second heat exchangers E2 and E1, a product gas with nitrogen as the main component is obtained. The remaining liquid phase is reheated in the second heat exchanger E2 and then merged into the pipeline of the first heat exchanger E1, and finally the product of the mixed hydrocarbon component is output.

[0060] The utility model has the advantages that the discharged tail gas can be separated and recovered, thus avoiding environmental pollution, improving the utilization value of the tail gas and increasing production efficiency.

[0061] The heat exchanger can be a plate-fin heat exchanger, a plate heat exchanger, a coiled-wound heat exchanger, a shell-and-tube heat exchanger or a combination thereof.

[0062] The distillation column can be a plate column, a packed column, a bubble cap column or a combination thereof.

[0063] The expander may be a turbo expander or a screw expander.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A slurry polyethylene tail gas recovery system, characterized in that: include: a first heat exchanger for cooling a first feed gas comprising an ethylene component and a second feed gas comprising a nitrogen component; A first distillation tower for distilling the first raw gas is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first distillation tower is connected to the liquid phase heavy component output pipe, and the gas phase outlet of the first distillation tower is connected to the gas phase output pipe; A second distillation tower for distilling the gas phase is connected to the first distillation tower through a gas phase output pipe, the liquid phase outlet of the second distillation tower is connected to the ethylene output pipe, the gas phase outlet of the second distillation tower is connected to the gas phase discharge pipe, and the gas phase output pipe passes through a second heat exchanger; The first separator for separating the second raw gas into gas and liquid is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first separator is connected to the first heat exchanger through a first pipeline, the gas phase outlet of the first separator is connected to the second separator through a second pipeline, the second pipeline passes through the second heat exchanger, the gas phase outlet of the second separator is connected to the gas phase inlet of the expander through a third pipeline, the third pipeline passes through the second heat exchanger, the gas phase outlet of the expander is connected to the nitrogen output pipe, and the liquid phase outlet of the second separator is connected to the mixed hydrocarbon output pipe through a pipeline.

2. The slurry polyethylene tail gas recovery system according to claim 1, characterized in that: The ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

3. A slurry polyethylene tail gas recovery system, characterized in that: include: a first heat exchanger for cooling a first feed gas comprising an ethylene component and a second feed gas comprising a nitrogen component; a second heat exchanger for further cooling the first raw gas, connected to the first heat exchanger through a pipeline; A distillation tower for distilling the first raw gas is connected to the second heat exchanger through a pipeline, the liquid phase outlet of the distillation tower is connected to the ethylene output pipe, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the gas phase outlet of the distillation tower is connected to the gas phase discharge pipe, and the gas phase discharge pipe passes through the second heat exchanger; The first separator for separating the second raw gas into gas and liquid is connected to the first heat exchanger through a pipeline, the liquid phase outlet of the first separator is connected to the first heat exchanger through a first pipeline, the gas phase outlet of the first separator is connected to the second separator through a second pipeline, the second pipeline passes through the second heat exchanger, the gas phase outlet of the second separator is connected to the gas phase inlet of the expander through a third pipeline, the third pipeline passes through the second heat exchanger, the gas phase outlet of the expander is connected to the nitrogen output pipe, and the liquid phase outlet of the second separator is connected to the mixed hydrocarbon output pipe through a pipeline.

4. The slurry polyethylene tail gas recovery system according to claim 3, characterized in that: The mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

5. A slurry polyethylene tail gas recovery system, characterized in that: include: a first heat exchanger for cooling a first feed gas comprising an ethylene component and a second feed gas comprising a nitrogen component; A second heat exchanger for further cooling the first raw gas and the second raw gas, connected to the first heat exchanger through a pipeline; A distillation tower for distilling the first raw gas is connected to the second heat exchanger through a pipeline, the liquid phase outlet of the distillation tower is connected to the ethylene output pipe, the ethylene output pipe passes through the second heat exchanger and the first heat exchanger in sequence, and the gas phase outlet of the distillation tower is connected to the gas phase discharge pipe, and the gas phase discharge pipe passes through the second heat exchanger; A separator for separating the second raw gas into gas and liquid is connected to the second heat exchanger through a pipeline. The gas phase outlet of the separator is connected to the gas phase inlet of the expander through a gas transmission pipeline. The gas transmission pipeline passes through the second heat exchanger. The gas phase outlet of the expander is connected to the nitrogen output pipe. The liquid phase outlet of the separator is connected to the mixed hydrocarbon output pipe through a pipeline. The mixed hydrocarbon output pipe passes through the second heat exchanger and the first heat exchanger in sequence. The nitrogen output pipe passes through the second heat exchanger and the first heat exchanger in sequence.

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