# US 10,767,924 B2 · Method for fractionating a stream of cracked gas to obtain an ethylene-rich cut and a stream of fuel, and related installation

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- Number: US 10,767,924 B2
- Document ID: US10767924B2
- Status: Granted
- Kind: B2
- Application number: 13/503,697
- Filed: 2010-10-26
- Published: 2012-10-25
- Granted: 2020-09-08
- Earliest claimed: 2009-10-27
- Assignees: Technip France
- Applicants: Jean-Paul Laugier; Yvon Simon
- Inventors: Jean-Paul Laugier; Yvon Simon
- Web page: https://patentgrep.com/patent/US10767924B2

## CPC

- F25J 3/062: {Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature}
- C10G 70/04: by physical processes
- F16D 21/00: Systems comprising a plurality of actuated clutches (for synchronisation F16D23/04)
- F16D 23/12: Mechanical clutch-actuating mechanisms arranged outside the clutch as such (specific for combined clutches F16D21/00; mechanisms specific for synchronisation F16D23/02)
- F25J 3/0219: {Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature}
- F25J 3/0233: {separation of CnHm with 1 carbon atom or more}
- F25J 3/0238: {separation of CnHm with 2 carbon atoms or more}
- F25J 3/0252: {separation of hydrogen (production of hydrogen containing gas in general C01B3/00, e.g. separation of hydrogen or hydrogen containing gases form gaseous mixtures at low temperatures C01B3/506)}
- C10G 2400/20: C2-C4 olefins
- F16D 2023/141: {characterised by using a fork; Details of forks}
- F25J 2205/04: in the feed line, i.e. upstream of the fractionation step
- F25J 2210/04: Mixing or blending of fluids with the feed stream
- F25J 2210/12: Refinery or petrochemical off-gas
- F25J 2215/62: Ethane or ethylene
- F25J 2245/02: Recycle of a stream in general, e.g. a by-pass stream
- F25J 2270/02: Internal refrigeration with liquid vaporising loop
- F25J 2270/04: Internal refrigeration with work-producing gas expansion loop
- F25J 2270/06: with multiple gas expansion loops
- F25J 2270/12: External refrigeration with liquid vaporising loop
- F25J 2270/60: Closed external refrigeration cycle with single component refrigerant [SCR], e.g. C1-, C2- or C3-hydrocarbons
- F25J 2290/34: Details about subcooling of liquids
- Y02P 30/40: Ethylene production
- F25J: LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS {OR LIQUEFIED GASEOUS} MIXTURES BY PRESSURE AND COLD TREATMENT {OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)}
- C10G: CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION (cracking to hydrogen or synthesis gas C01B; cracking or pyrolysis of hydrocarbon gases to individual hydrocarbons or mixtures thereof of definite or specified constitution C07C; cracking to cokes C10B); RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

This method includes introducing a downstream stream (140) of cracked gas from a downstream heat exchanger (58) in a downstream separator (60) and recovering, at the head of the downstream separator (60), a high-pressure fuel gas stream (144). The method includes the passage of the stream (144) of fuel through the downstream exchanger (58) and an intermediate exchanger (50, 54) to form a reheated high-pressure fuel stream (146), the expansion of the reheated high-pressure fuel stream (146) in at least a first dynamic expander (68) and the passage of the partially expanded fuel stream (148) from the intermediate exchanger (50, 54) in a second dynamic expander (70) to form an expanded fuel stream (152). The expanded fuel stream (152) from the second dynamic expander (70) is reheated in the downstream heat exchanger (58) and in the intermediate heat exchanger (50, 54).

## Claims

### Claim 1

A method for fractionating a stream of cracked gas from a hydrocarbon pyrolysis installation to obtain an ethylene-rich cut and a stream of fuel having a low C2+ hydrocarbon content, the method comprising the following steps:
cooling and introducing in at least one compressor a raw cracked gas stream to form a compressed cracked gas stream;
forming a reboiling fraction from the compressed cracked gas stream;
introducing the reboiling fraction into a reboiling heat exchanger of a fractionating column;
partial condensing of the reboiling fraction in the reboiling heat exchanger;
introducing a stream foiined from the reboiling fraction into a first upstream separating drum to form an upstream stream of raw cracked gas;
upstream cooling of the upstream stream of raw cracked gas and partial condensation of the upstream stream of raw cracked gas by at least partial heat exchange with a coolant fluid circulating in a first external refrigeration cycle and separation of an upstream liquid in an upstream drum to form an intermediate stream of cracked gas pre-cooled to a first temperature below −63° C.;
intermediate cooling of the intermediate stream of cracked gas and partial condensation of the inteiiiiediate stream of cracked gas in at least one intermediate heat exchanger and separation of an intermediate liquid in at least one intermediate separation drum to form a downstream stream of cracked gas cooled to a second temperature lower than the first temperature;
downstream cooling of the downstream stream of cracked gas and partial condensation of the downstream stream of cracked gas in a downstream heat exchanger to a third temperature lower than the second temperature;
introducing the partially condensed downstream stream of cracked gas obtained from the downstream heat exchanger in a downstream separator;
recovering, at the head of the downstream separator, a high-pressure gas stream of fuel, with a low C2+ hydrocarbon content, and recovering, at the bottom of the downstream separator, a downstream liquid, with a high C2+ hydrocarbon content;
passing the high-pressure fuel stream through the downstream exchanger and the at least one intermediate exchanger to form a reheated high-pressure fuel stream;
expansion of the reheated high-pressure fuel stream in at least a first dynamic expander to obtain a partially expanded fuel stream;
heating the partially expanded fuel stream through the downstream exchanger and the at least one intermediate exchanger;
passing the partially expanded flow of fuel from the at least one intermediate exchanger into a second dynamic expander to form an expanded stream of fuel;
reheating the expanded fuel stream from the second dynamic expander in the downstream heat exchanger and in the at least one intermediate heat exchanger;
compressing the reheated expanded fuel stream in at least one fuel compressor coupled to at least one turbo-expander of one of the first dynamic expander and the second dynamic expander to form the stream of fuel having a low C2+ hydrocarbon content,
wherein the intermediate cooling of the intermediate stream of cracked gas to the second temperature is carried out exclusively by heat exchange with the high pressure fuel stream, by heat exchange with the partially expanded fuel stream, by heat exchange with the expanded fuel stream, by heat exchange with a first fraction of the intermediate liquid recovered in the intermediate cooling step and the downstream liquid recovered in the downstream cooling step from the downstream separator, the heat exchanges being carried out in the intermediate heat exchanger, without heat exchange with an external coolant fluid circulating in a refrigeration cycle,
wherein a processing step comprises the introduction of at least said upstream liquid, and a second fraction of said intermediate liquid in a fractionating column and the production in the fractionating column of a stream with a high ethylene content intended to form the ethylene-rich cut.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising recovery of the downstream liquid and reheating thereof through the downstream heat exchanger, and the intermediate heat exchanger,
the downstream liquid being sub-cooled in the downstream heat exchanger before it is reheated in the downstream heat exchanger, then in the intermediate heat exchanger.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the first fraction of the intermediate liquid is sub-cooled before being reintroduced into the downstream heat exchanger, then in the intermediate heat exchanger.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the first fraction of the intermediate liquid and the downstream liquid evaporates during passage in the downstream heat exchanger, and passage in the intermediate heat exchanger to provide the intermediate cooling of the intermediate stream of cracked gas, to form a gas recirculation flow, the gas recirculation flow being mixed with the stream of raw cracked gas, before the passage of the raw cracked gas in the at least one compressor.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the entirety of the overhead stream from the fractionating column is conveyed through the upstream heat exchanger.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the first dynamic expander comprises at least one dynamic turbo expander, and the second dynamic expander comprises at least one dynamic turbo-expander.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the molar content of hydrogen in the high-pressure fuel stream is greater than 75%.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the first temperature is below −63° C., the second temperature is below −85° C., and the third temperature is below −120° C.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the entirety of the overhead stream from the fractionating column is conveyed through the upstream heat exchanger, before being mixed with the raw cracked gas, without a fraction of the overhead stream being condensed to be sent to the fractionating column as reflux.