Ethylene device driving method of front-end deethanization process

A technology for ethylene plant and ethane, which is applied in ethylene production, hydrotreating process, petroleum industry, etc., to achieve the effect of reducing losses and reducing the amount of ultra-high pressure steam

Active Publication Date: 2015-02-11
PETROCHINA CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] Therefore, for the start-up of the ethylene unit of the existing pre-deethanization process, although the cracked gas compressor is first operated with nitrogen, the cold box and the demethanizer system are pre-cooled with nitrogen, which shortens the start-up time. After the ethylene raw material, because most of the process systems have not reached the normal operating conditions and need to adjust the time for operation, there are still quenching systems, the outlet of the end stage of the cracked gas compressor, the top of the C3 absorption tower, the outlet of the C2 hydrogenation reactor, the cold problem with the cold box and demethanizer overhead material flaring, no hydrocarbon material is flaring until the cold box and demethanizer system reaches normal operating conditions

Method used

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  • Ethylene device driving method of front-end deethanization process

Examples

Experimental program
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Effect test

Embodiment 1

[0045] figure 1Shown is the ethylene plant start-up cycle diagram for the existing pre-deethanizer process. Natural gas 1 enters fuel gas system F2 to provide fuel gas 4 to cracking furnace H1. Before cracking furnace H1 feeds ethylene raw material 2, ethylene 35 is fed into deethanizer C2 and ethylene rectification tower C5, propylene 36 is fed into deethanizer C2, deethanizer is operated under pressure circulation, and ethylene rectification tower is fully refluxed Operation; propylene 36 is added to the depropanizer C4 and propylene rectification tower C6, and the two towers realize full reflux operation; nitrogen 31 is added from the suction port of the cracked gas compressor K1, and then passed through the cracked gas compressor K1 and the carbon three absorption tower C1 , carbon two hydrogenation reactor R1, cold box B1 and demethanizer C3, nitrogen 32 and 33 are returned to the inlet of cracked gas compressor K1 through the process flow of hydrogen methane separation ...

Embodiment 2

[0047] figure 2 Shown is an improvement diagram of the start-up cycle of an ethylene plant for the pre-deethanization process of the present invention. During the normal operation of the ethylene plant, the ethane 41 at the bottom of the ethylene rectification tower C5 is collected in the temporary ethane spherical tank F3. After the nitrogen precooling is completed after the start-up of the ethylene plant, natural gas 43 is introduced into the cracked gas compressor K1 inlet to replace the nitrogen in the compression and separation process system, and the replaced nitrogen is discharged from the streams 51 and 53 to the flare. Introduce ethane 42 from the ethane spherical tank F3 in proportion to the inlet of the cracking gas compressor K1, use the mixed gas of natural gas 43 and ethane 42 as the circulating gas of the cracking gas compressor K1 to pre-cool the separation system such as the cold box, hydrogen 37 is added from the inlet of the C2 hydrogenation reactor R1, th...

Embodiment 3

[0049] An embodiment of the present invention will be described below with respect to a set of ethylene plant of 800kt / a pre-deethanization separation process.

[0050] Two days before the planned shutdown of the ethylene plant, the ethane produced by the ethylene plant began to be collected, and the ethane 41 at the bottom of the ethylene rectification tower C5 was collected in the temporary ethane spherical tank F3, generally storing more than 500 tons of ethane. Prepare start-up materials such as natural gas, ethane and hydrogen. Table 1 shows typical compositions of natural gas and ethane.

[0051] Table 1 Typical composition of natural gas and ethane

[0052] Component

N 2

CO 2

CH 4

C 2 h 4

C 2 h 6

C 3 h 8

C 4 h 10

Natural gas, volume fraction / %

1.67

0.35

92.5

0.0

4.1

0.87

0.51

Circulating ethane, volume fraction / %

0.0

0.0

0.0

5.0

95.0

0.0

0.0 ...

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Abstract

The invention relates to an ethylene device driving method of a front-end deethanization separation process. The method comprises the following steps: in the operation period of recycle gas of a cracking gas compressor, returning materials in a cold box hydrogen methane separation tank and on the tower top of a demethanizer to a cracking furnace after the content of nitrogen in the recycle gas is qualified; arranging a temporary ethane spherical tank, a connecting pipeline and heat exchange facilities, collecting ethane acquired from the tower bottom of an ethylene rectification tower into the ethane spherical tank before shut-down repair of an ethylene device, and in the driving period of the ethylene device, using ethane as supplementary ethane of a first-section suction inlet of the cracking gas compressor after recycling cooling energy of ethane in the spherical tank; and arranging the connecting pipeline and heat exchange facilities among the tower bottom of the demethanizer, the first-section suction inlet of the cracking gas compressor and the cracking furnace, and in the driving period of the ethylene device, recycling the cooling energy of the materials at the tower bottom of the demethanizer, and then returning to the cracking furnace or the first-section suction inlet of the cracking gas compressor. According to the method disclosed by the invention, a large amount of hydrocarbon material discharge torches cannot be generated basically in the driving period of the ethylene device, and the driving time can also be shortened.

Description

technical field [0001] The invention relates to a start-up method of an ethylene plant in a pre-deethanization process. Background technique [0002] James H.Walker of Equistar Chemical Company in the United States invented a method for starting up an olefin production unit (US7270740B2). A stream of artificial synthetic gas is introduced into the first section of the suction port of the cracked gas compressor. The synthetic gas is composed of hydrogen, methane, ethane and propane It is composed of two or more components, wherein the mass fraction of each component is close to the mass fraction of the actual cracked gas components in the quenching system. When the ethylene unit is started up, the cracking furnace does not feed ethylene raw material and the quenching system is not in operation. First, artificial synthetic gas is introduced to start the cracking gas compressor. When the outlet pressure of the cracking gas compressor reaches 17-19Mpa, the synthetic gas enters t...

Claims

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Application Information

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IPC IPC(8): C10G67/00C07C4/04C07C11/04
CPCC07C4/04C07C11/04C10G67/00C10G2300/1092C10G2400/20Y02P30/40
Inventor 卢光明
Owner PETROCHINA CO LTD
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