CN105567292B - A kind of method for reducing ethylene unit energy consumption - Google Patents

A kind of method for reducing ethylene unit energy consumption Download PDF

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CN105567292B
CN105567292B CN201410542720.0A CN201410542720A CN105567292B CN 105567292 B CN105567292 B CN 105567292B CN 201410542720 A CN201410542720 A CN 201410542720A CN 105567292 B CN105567292 B CN 105567292B
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oil
tower
ethylene unit
energy consumption
unit energy
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CN105567292A (en
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郭莹
王国清
刘同举
杜志国
刘俊杰
田勇
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Abstract

The invention discloses a kind of method for reducing ethylene unit energy consumption, it is characterised in that the cracking gas of cracking outlet of still sends into oil scrubber after being cooled down through quencher, carries out material separation, and quench oil is drawn from oil scrubber bottom of towe, and part quench oil is sent to quencher;Part quench oil returns to oil scrubber;Part quench oil enters extraction tower, and with the solvent extraction preheated through pyrolysis furnace preheating section in extraction tower, extraction tower tower top material returns to oil scrubber after desolventizing, and extraction tower materials at bottom of tower pitch is mutually drawn.

Description

A kind of method for reducing ethylene unit energy consumption
Technical field
It is to be related to a kind of method for reducing ethylene unit energy consumption furtherly the present invention relates to ethylene production field.
Background technology
At present, main ethylene unit produces ethene, propylene, butadiene, aromatic hydrocarbons etc. using steam thermal cracking process in the world Basic organic chemical raw material.The raw materials such as lighter hydrocarbons, naphtha, hydrogenation tail oil are blended in industrial crack with a certain proportion of dilution steam generation There is cracking reaction in stove under hot conditions, pyrolysis product through the operation final production such as over-quenching, compression, separation go out ethene, The industrial chemicals such as propylene, butadiene.
Pyrolysis furnace is the core of ethylene unit.Pyrolysis furnace high fume temperature, is ethylene unit common problem, due to Convection section is not enough to the recovery of heat, and amount of heat is discharged with flue gas and wasted, and causes that cracking furnace thermal efficiency is low, and ethylene unit is comprehensive Close high energy consumption.
Chilling system is the throat of ethylene unit, and it is made up of equipment such as quencher, oil scrubber, water scrubbers, is carry point From cracking distillate (gasoline, diesel oil, fuel oil) component and the task of recovery process water, while still reclaiming heat in cracking process The key equipment of amount.The cracking gas that the outlet of industrial pyrolysis furnace waste heat boiler comes sends into oil in quencher after quench oil spraying cooling Tower bottom is washed, after backflow cooling, the light component in pyrolysis product continues cool to 40 from oil scrubber Base top contact into water scrubber DEG C or so, into follow-up compression piece-rate system.
, all from the UTILIZATION OF VESIDUAL HEAT IN of device inside quench oil, minority is or not most of dilution steam generation required for cracking process Foot point is supplemented by pipe network steam.Oil scrubber bottom temperature is higher, more, device by utilizing waste heat better, the outer benefit of utilization of steam generation Steam consumption is fewer.Therefore the height of oil scrubber bottom temperature directly determines the size of waste heat recovery volume, the fortune of chilling system The bad energy consumption height to ethylene unit of acting charitably has important influence, so as to also contribute to the production cost of device.
Regard ethylene unit chilling system as an entirety, inflow is pyrolysis product, and outflow is cracking gas and cracking Distillate;Quench oil, process water etc. are in system interior circulation.Therefore ethylene unit chilling system runs well will ensure two Balance, heat balance, material balance.Heat balance is that the heat for bringing chilling system into by cracking gas will be by occurring dilution steam generation Utilize Deng heat exchange mode.Material balance is then relative complex, because pyrolysis product pyrolysis product can occur after entering chilling system The reaction such as polymerization, produces change, and chilling system is needed the pyrolysis product discharge after change, steady with component in keeping chilling system It is fixed.
Ethylene quenching system practical problem now aborning is exactly low oil scrubber bottom temperature, and chilling oil viscosity is high.It is anxious Cold oil bottom temperature is low, and dilution steam generation temperature difference of heat exchanger is small, dilution steam generation generating capacity wretched insufficiency, it is therefore desirable to which a large amount of steam are mended Enter system;Chilling oil viscosity is high, and the power consumption of quenching oil circulation pump is high, causes ethylene unit energy consumption to remain high, when viscosity is too high Can also blocking pipeline cause parking.
The reason for causing ethylene quenching system problem is exactly that the asphalitine of generation in quench oil cannot be discharged in time.In order to give The cracking gas cooling that pyrolysis furnace is produced, quench oil is circulated between quencher and oil wash tower reactor in chilling system, and its internal circulating load is past It is past to reach thousands of tphs, and the extraction for cracking distillate only has tens tphs, quench oil is stagnant for a long time in system Stay, produce a large amount of asphalitines, viscosity significantly to raise.And in order to control chilling oil viscosity, oil wash bottom temperature can only be reduced to subtract The speed of few asphalitine generation.But oil wash bottom temperature is reduced in the case of pyrolysis furnace load identical, quench oil can be increased Internal circulating load, so that the time that quench oil is detained in system is longer, increased the amount of asphalitine generation again.So actual production In oil wash bottom temperature can only be maintained 180 DEG C or so, just can guarantee that the pitch of the asphalitine and discharge generated in quench oil Matter balances each other, and maintains quench oil viscosity stabilization.Here it is 210 DEG C of oil scrubber tower reactor design temperature, can actual motion less than 190 DEG C Basic reason.
At present, using adding quenched flux oil, adding viscosity reductant and using three kinds of methods of visbreaking tower on commercial plant, can only It is cost to reduce oil scrubber bottom temperature, chilling oil viscosity is controlled reluctantly, causes ethylene unit energy consumption to remain high.
First method is to add quenched flux oil (pyrolysis gas oil) reduction viscosity, largely pyrolysis gas oil will be blended to urgency In cold oil, its side effect is very big.First, internal circulating load of the pyrolysis gas oil in oil scrubber can be increased, oil scrubber tower reactor to tower is increased The gas phase load at middle part, correspondingly reduces the disposal ability of oil scrubber;Secondly, in pyrolysis gas oil containing substantial amounts of styrene, The components such as naphthalene, indenes, when they are circulated with quench oil, it may occur that polymerisation produces polymer, and accumulates in oil scrubber On column plate or filler, heat transfer and the mass transfer effect of influence column plate and filler rise tower pressure difference, and the disposal ability of tower declines;Again It is secondary, due to the increase of pyrolysis gas oil internal circulating load, part can be contained in the Pyrolysis fuel oil PFO of drippolene and the tower reactor extraction of tower top The component of diesel oil, has influence on the quality of drippolene and fuel oil, can cause that the operation of follow-up quenching water column deteriorates when serious; Finally, due to the amount of quench oil is very big, therefore in order to reduce the viscosity of quench oil, it usually needs substantial amounts of cracking bavin is mixed for a long time Oil.In this way, it is impossible to reduce asphalitine growing amount, chilling oil viscosity can only be typically controlled in 1000~2000mm2/s (50 DEG C), oil scrubber bottom temperature is without significantly improving.
Viscosity reductant be in recent years domestic and international research department and ethene patent business work out it is various it is suitable reduction quench oils glue The chemical agent of degree, visbreaking target is realized by adding the activity of chemical assistant suppression polymerisation free radical.CN 101062880A proposes a kind of Reduce viscosity agent being made up of polymerization inhibitor, dispersant and matal deactivator, be polymerized with suppression, Prevent aggregation and the effect of passivating metallic surfaces.Although add viscosity reductant reduces the formation speed of asphalitine to a certain extent, It is do not have any help to asphalitine discharge chilling system, it is impossible to fundamentally solve that chilling oil viscosity is high and oil scrubber tower reactor temperature The low problem of degree.Actually used middle viscosity reductant is seldom used alone, and is while using visbreaking tower technology, to be made with viscosity reductant It is supplementary means.
Visbreaking tower technology is the quench oil that will be exported from quenching oil circulation pump, under the control of temperature control valve (TCV), with The ethane cracking gas that Control for Pyrolysis Furnace Area is come is contacted in nozzle mixer, and the light component in quench oil is vaporized, with cracking gas Into visbreaking tower.The light component vaporized in ethane cracking gas and quench oil enters oil scrubber tower reactor, non-vapour from visbreaking column overhead The heavy liquid phase component of change enters visbreaking tower tower reactor, used as byproduct (Pyrolysis fuel oil PFO) output to tank field.So, it is selective Ground fractionates out the heavier feeds containing more asphalitine from quench oil and stays in systems light material, makes circulation quench oil In light components concentration increase, so as to reduce quench oil viscosity.But in fact, visbreaking column overhead temperatures are at 250-290 DEG C, only Light component below this temperature can be returned to oil scrubber, there are a large amount of low viscous components in the fuel oil of discharge, discharge pitch Efficiency it is low.Simultaneously as quench oil will be contacted with 500 DEG C or so of ethane stove cracking gas, stop increased urgency at high temperature Cold oil studies on asphaltene growing amount, adversely affects to chilling oil viscosity.In actual motion, can only be by oil scrubber bottom temperature 180 DEG C or so are limited in, chilling oil viscosity can be just controlled.
Prior art can only reduce oil scrubber tower reactor due to the asphalitine discharge that will effectively cannot be generated in quench oil Temperature controls chilling oil viscosity, considerably increases ethylene unit energy consumption.Especially, cracking stock progressively lighting in recent years, by In the Pyrolysis fuel oil PFO for producing seldom, i.e., discharge rate is smaller under identical internal circulating load, that is to say, that quench oil is detained in system Time is longer, and the asphalitine of generation is more, and what can be discharged is less so that prior art loses effect substantially.Therefore, it is badly in need of out Send out technology a kind of, reduce chilling oil viscosity, improve quenching oil column bottom temperature, improve cracking furnace thermal efficiency, reduce ethylene unit Comprehensive energy consumption.
The content of the invention
To solve problems of the prior art, the invention provides a kind of method for reducing ethylene unit energy consumption.It is logical The viscosity of solvent extraction reduction quench oil is crossed, chilling oil temperature is improved by improving oil scrubber bottom temperature, and then increase dilute Steam production is released, extract oil reduces pyrolysis furnace exhaust gas temperature, reduces by entering solvent recovery tower after convection section in cracking furnace heating The comprehensive energy consumption of ethylene unit.
It is an object of the invention to provide a kind of method of above-mentioned reduction ethylene unit energy consumption, it is characterised in that cracking The cracking gas that outlet of still comes sends into oil scrubber after being cooled down through quencher, carries out material separation, and quench oil is drawn from oil scrubber bottom of towe, Part quench oil is sent to quencher;Part quench oil returns to oil scrubber;Part quench oil enters extraction tower carries out solvent extraction, extracting Column overhead material heats laggard solvent recovery tower through convection section in cracking furnace, and oil scrubber, extraction tower materials at bottom of tower are returned after desolventizing Pitch is mutually drawn.
Oil scrubber bottom temperature of the invention brings up to 190-250 DEG C, is preferably increased to 195-235 DEG C.
During extraction tower solvent extraction, solvent is 0.01-20, preferably 0.5-5 with the weight ratio of quench oil;Extracting pressure tower It is 0.1MPa-10MPa, the temperature of extraction tower is 0 DEG C -250 DEG C.
The solvent is selected from the one kind in C2-C6 alkane or alkene or its mixture, preferably in C3-C5 alkane Plant or its mixture.
Described quench oil is the oil distillate of oil scrubber tower reactor in ethylene unit chilling system, and its typical composition is many cyclophanes Hydrocarbon, colloid, asphalitine.Described ethylene unit is mainly made up of the system such as industrial pyrolysis furnace and chilling, compression, separation, chilling System mainly includes quencher, oil scrubber, water scrubber.
The recovery pressure tower used during solvent recovery is 0.1MPa-10Mpa, and temperature is 50 DEG C -300 DEG C.
The method of the present invention can specifically use following technical scheme:
The Pintsch process gas for cracking outlet of still (contains from H2Constituted to Pyrolysis fuel oil PFO etc., also comprising dilution steam generation), warp Cross waste heat boiler to reclaim heat and enter quencher after being cooled, with quench oil directly contact, cooling.Cracking gas after cooling and Quench oil enters oil scrubber together, carries out Oil-gas Separation, and tower reactor draws circulation quench oil, into Dilution steam generator 8, produces Dilution steam generation.Circulation chilling oil temperature is improved by improving the bottom temperature mode of ethylene unit chilling system oil scrubber 1, so as to carry The generating capacity of highly diluted steam.
It is divided into three tunnels after circulation quench oil is cooled, pyrolysis furnace quencher 4 is removed all the way;All the way by technique water preheater 6 Oil scrubber is returned again to, after leading up to the pressurization of booster pump 5, into the quench oil charging aperture of extraction tower 2.
Solvent enters the solvent feed mouthful of extraction tower 2, and solvent implements extracting with quench oil in extraction tower 2, and what is obtained takes out The extracting oil export of oily (mixture of solvent and quench oil light component) from the top of extraction tower is carried to draw, the raffinate pitch for obtaining from The asphalt outlet for extracting tower bottom is drawn.
Extract oil is absorbed after flue gas heat raises own temperature, into solvent recovery tower 3 by convection section in cracking furnace 7 Import.Extract oil is separated into solvent and visbreaking quench oil in solvent recovery tower, and solvent is drawn from column overhead is reclaimed, visbreaking chilling Oil is drawn from bottom of towe.The visbreaking quench oil drawn from solvent recovery tower 3 returns to oil scrubber 1, so as to effectively reduce overall quench oil Viscosity.
The viscosity that the present invention passes through solvent extraction reduction quench oil, chilling oil temperature is improved by improving oil scrubber bottom temperature Degree, and then dilution steam generation yield is increased, extract oil is heated by convection section in cracking furnace, reduces pyrolysis furnace exhaust gas temperature, is reduced The comprehensive energy consumption of ethylene unit.
Brief description of the drawings
Fig. 1 system schematics of the invention
Description of reference numerals:
1 oil scrubber, 2 extraction towers, 3 solvent recovery towers, 4 quenchers, 5 booster pumps, 6 preheaters, 7 pyrolysis furnace preheating sections, 8 is dilute Release steam generator.
Specific embodiment
With reference to embodiment, the present invention is further illustrated.
Embodiment:
Certain ethylene unit produces 200k/a, year operation 8000h, ethylene yield 25t/h per year.Crack the Pintsch process gas of outlet of still (contain from H2Constituted to Pyrolysis fuel oil PFO etc., also comprising dilution steam generation), after waste heat boiler reclaims heat and is cooled, always It is 147t/h to measure, into quencher, with quench oil directly contact, cooling.Cracking gas and quench oil after cooling enter oil together Tower is washed, Oil-gas Separation is carried out, tower reactor draws circulation quench oil, into Dilution steam generator, produces dilution steam generation, circulates chilling Oily total amount is 1200t/h.It is divided into three tunnels after circulation quench oil is cooled, pyrolysis furnace quencher is removed all the way;All the way by process water Preheater returns again to oil scrubber, all the way into extraction tower quench oil charging aperture, one hydro carbons is drawn from separation system of ethylene unit Product enters extraction tower solvent feed mouthful, by solvent extraction in extraction tower, from extracting tower bottom removing based on pitch Heavy constituent 1.5t/h.After the extract oil that extracting tower top is obtained is preheated through convection section in cracking furnace, it is separated into solvent recovery tower and is followed Ring solvent and visbreaking quench oil.Visbreaking quench oil returns to oil scrubber, reduces chilling oil viscosity.Specific embodiment process conditions are such as Under.
Comparative example
Certain ethylene unit produces 200kt, year operation 8000h, ethylene yield 25t/h per year, and chilling system charging total amount is 147t/ H, oil scrubber bottom draw circulation quench oil by Dilution steam generator generation dilution steam generation, then go pyrolysis furnace quencher to Oil scrubber is returned after cracking gas cooling.Chilling oil viscosity 2000mm2/ s, consumes tempering oil 4t/h, and oil scrubber bottom temperature is 178 DEG C, generation dilution steam generation only has 12t/h.Ethylene unit energy consumption is 643GJ/h.

Claims (9)

1. it is a kind of reduce ethylene unit energy consumption method, it is characterised in that cracking outlet of still cracking gas through quencher cool down After send into oil scrubber, carry out material separation, draw quench oil from oil scrubber bottom of towe, part quench oil is sent to quencher;Part is anxious Cold oil returns to oil scrubber;Part quench oil enters extraction tower carries out solvent extraction, and extraction tower tower top material adds through convection section in cracking furnace The laggard solvent recovery tower of heat, returns to oil scrubber after desolventizing, extraction tower materials at bottom of tower pitch is mutually drawn.
2. the method for reducing ethylene unit energy consumption as claimed in claim 1, it is characterised in that oil scrubber bottom temperature is 190- 250℃。
3. the method for reducing ethylene unit energy consumption as claimed in claim 2, it is characterised in that oil scrubber bottom temperature is 195- 235℃。
4. the method for reducing ethylene unit energy consumption as claimed in claim 1, it is characterised in that the solvent is selected from C2-C6 One kind or its mixture in alkane or alkene.
5. the method for reducing ethylene unit energy consumption as claimed in claim 4, it is characterised in that the solvent is selected from C3-C5 One kind or its mixture in alkane or alkene.
6. the method for reducing ethylene unit energy consumption as claimed in claim 1, it is characterised in that enter the solvent and urgency of extraction tower The weight ratio of cold oil is 0.01-20.
7. the method for reducing ethylene unit energy consumption as claimed in claim 6, it is characterised in that enter the solvent and urgency of extraction tower The weight ratio of cold oil is 0.5-5.
8. the as claimed in claim 1 method for reducing ethylene unit energy consumption, it is characterised in that the pressure of the extraction tower is 0.1MPa-10MPa, tower top temperature is 0 DEG C -250 DEG C.
9. the method for reducing ethylene unit energy consumption as claimed in claim 1, it is characterised in that the pressure of the solvent recovery tower It is 0.1MPa-10MPa;Temperature is 50 DEG C -300 DEG C.
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CN103305257A (en) * 2012-03-16 2013-09-18 中国石油化工股份有限公司 Method for reducing viscosity of quenching oil of ethylene unit

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Publication number Priority date Publication date Assignee Title
CN103305257A (en) * 2012-03-16 2013-09-18 中国石油化工股份有限公司 Method for reducing viscosity of quenching oil of ethylene unit

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