CN105567291A - Method for reducing ethene device energy consumption - Google Patents
Method for reducing ethene device energy consumption Download PDFInfo
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- CN105567291A CN105567291A CN201410542716.4A CN201410542716A CN105567291A CN 105567291 A CN105567291 A CN 105567291A CN 201410542716 A CN201410542716 A CN 201410542716A CN 105567291 A CN105567291 A CN 105567291A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
Abstract
The invention discloses a method for reducing ethene device energy consumption. The method comprises cooling pyrolysis gas from an outlet of a pyrolysis furnace through a quench cooler, feeding the cooled pyrolysis gas into an oil washing tower, carrying out substance separation, discharging quenching oil from the bottom of the oil washing tower, feeding a part of the quenching oil into the quench cooler, returning a part of the quenching oil back to the oil washing tower, feeding a part of the quenching oil into an extraction tower, carrying out solvent-based extraction, discharging an asphalt phase at the bottom of the extraction tower, reducing pressure of the material at the top of the extraction tower, feeding the material subjected to pressure reduction into a solvent recovery tower, separating the solvent and quenching oil subjected to visbreaking, returning the quenching oil subjected to visbreaking back to the oil washing tower, returning the solvent back to the pyrolysis furnace and carrying out pyrolysis.
Description
Technical field
The present invention relates to ethylene production field, furtherly, relate to a kind of method reducing ethylene unit energy consumption.
Background technology
At present, main ethylene unit adopts steam heat cracking technology to produce the basic organic chemical raw materials such as ethene, propylene, divinyl, aromatic hydrocarbons in the world.The raw materials such as lighter hydrocarbons, petroleum naphtha, hydrogenation tail oil and a certain proportion of dilution steam generation are blended in industrial pyrolysis furnace and scission reaction occur under hot conditions, and split product goes out the industrial chemicals such as ethene, propylene, divinyl through operation final production such as over-quenching, compression, separation.
Quenching system is the throat of ethylene unit, it is made up of equipment such as quencher, oil scrubber, water wash columns, carry the task of separating and cracking distillate (gasoline, diesel oil, oil fuel) component and recovery process water, simultaneously or in cracking process, reclaim the key equipment of heat.The splitting gas that the outlet of industrial pyrolysis furnace waste heat boiler comes is sent into bottom oil scrubber at quencher after quenching oil spraying cooling, after reflux cooling, light constituent in split product, from oil scrubber Base top contact, enters water wash column and continues to be cooled to about 40 DEG C, enter follow-up compression separation system.
Most of dilution steam generation required for cracking process all derives from the UTILIZATION OF VESIDUAL HEAT IN of device internal quench oil, and minority insufficient section is supplemented by pipe network steam.Oil scrubber bottom temperature is higher, steam generation more, and it is better that device by utilizing waste heat utilizes, and outer benefit steam consumption is fewer.Therefore the height of oil scrubber bottom temperature directly determines the size of waste heat recovery volume, and the energy consumption height of operation quality on ethylene unit of quenching system has important impact, thus also affects the production cost of device.
Ethylene unit quenching system is regarded as an entirety, inflow be split product, outflow be splitting gas and cracking distillate; Quenching oil, process water etc. are all at system internal recycle.Therefore ethylene unit quenching system runs well and will ensure two balances, heat balance, material balance.The heat that namely heat balance brings quenching system into by splitting gas will utilize by there is the heat exchange modes such as dilution steam generation.Material balance is relative complex then, because split product, after entering quenching system, the reactions such as polymerization can occur, changes, and quenching system needs the split product after change to discharge, and stablizes to keep component in quenching system.
Ethylene quenching system now practical problems is aborning exactly that oil scrubber bottom temperature is low, and quenching oil viscosity is high.Quenching oil bottom temperature is low, and dilution steam generation temperature difference of heat exchanger is little, dilution steam generation generating capacity wretched insufficiency, therefore needs a large amount of steam to fill into system; Quenching oil viscosity is high, and the power consumption of quenching oil circulation pump is high, causes ethylene unit energy consumption to remain high, also can cause parking by blocking pipeline when viscosity is too high.
The reason of ethylene quenching system problem is caused to be exactly that the bituminous matter generated in quenching oil cannot be discharged in time.In order to the splitting gas cooling produced to pyrolyzer, in quenching system, quenching oil circulates between quencher and oil wash tower reactor, it is per hour that its internal circulating load often reaches a few kiloton, and the extraction of cracking distillate only has tens tphs, quenching oil is detained for a long time in system, produce a large amount of bituminous matter, viscosity significantly raises.And in order to control quenching oil viscosity, the speed that oil wash bottom temperature generates to reduce bituminous matter can only be reduced.Reduce oil scrubber still temperature when pyrolyzer load is identical, quenching oil internal circulating load can be increased, to such an extent as to the time that quenching oil is detained in system is longer, turn increase the amount that bituminous matter produces.So oil wash bottom temperature can only be maintained about 180 DEG C in actual production, the bituminous matter generated in guarantee quenching oil and the bituminous matter of discharge balance each other, and maintain quenching oil stable viscosity.Oil scrubber tower reactor design temperature 210 DEG C that Here it is, can actual motion less than the basic reason of 190 DEG C.
At present, on full scale plant, employing adds modified thinning oil, adds viscosity depressant and use visbreaking tower three kinds of methods, to reduce oil scrubber bottom temperature for cost, can only control quenching oil viscosity reluctantly, cause ethylene unit energy consumption to remain high.
First method adds modified thinning oil (Pyrolysis gas oil PGO) to reduce viscosity, and by a large amount of Pyrolysis gas oil PGO blending in quenching oil, its side effect is very large.First, the internal circulating load of Pyrolysis gas oil PGO in oil scrubber can be increased, strengthen the gas phase load in the middle part of oil scrubber tower reactor to tower, correspondingly reduce the processing power of oil scrubber; Secondly, containing a large amount of components such as vinylbenzene, naphthalene, indenes in Pyrolysis gas oil PGO, when they are along with quenching oil circulation time, polymkeric substance can be produced by polymerization reaction take place, and on the column plate accumulating in oil scrubber or filler, affect heat transfer and the mass transfer effect of column plate and filler, make tower pressure reduction increase, the processing power of tower declines; Again, due to the increase of Pyrolysis gas oil PGO internal circulating load, can component containing part diesel oil in the pyrolysis gasoline of tower top and the Pyrolysis fuel oil PFO of tower reactor extraction, have influence on the quality of pyrolysis gasoline and oil fuel, the operation of follow-up quenching water column time serious, can be made to worsen; Finally, because the amount of quenching oil is very large, therefore in order to reduce chilling oil viscosity, usual needs mix a large amount of Pyrolysis gas oil PGOs for a long time.Adopt in this way, cannot reduce bituminous matter growing amount, quenching oil viscosity generally can only control at 1000 ~ 2000mm
2/ s (50 DEG C), oil scrubber bottom temperature is without significantly improving.
Viscosity depressant is that research department and ethene patent business worked out the chemical agent of various applicable reduction quenching oil viscosity both at home and abroad in recent years, suppresses the activity of polyreaction free radical to realize visbreaking target by adding chemical assistant.CN101062880A proposes a kind of quench oil viscosity reductant be made up of stopper, dispersion agent and metal passivator, has the effect suppressing polymerization, prevent gathering and passivating metallic surfaces.Although add viscosity depressant to reduce bitum formation speed to a certain extent, quenching system is discharged without any help to bituminous matter, fundamentally cannot solve the problem that quenching oil viscosity is high and oil scrubber bottom temperature is low.In actual use, viscosity depressant is seldom used alone, and is all using visbreaking tower technology while, using viscosity depressant as supplementary means.
Visbreaking tower technology be the quenching oil will exported from quenching oil circulation pump, under the control of temperature control valve (TCV), with Control for Pyrolysis Furnace Area come ethane cracking gas contact in nozzle mixer, the light constituent in quenching oil is vaporized, and enters visbreaking tower with splitting gas.The light constituent of vaporizing in ethane cracking gas and quenching oil enters oil scrubber tower reactor from visbreaking tower tower top, and the heavy liquid phase component of not vaporizing enters visbreaking tower tower reactor, outputs to tank field as byproduct (Pyrolysis fuel oil PFO).Like this, fractionate out from quenching oil selectively containing more bitum heavier feeds and light material is stayed in systems in which, the light component concentration in quench oil circulated is increased, thus reducing quenching oil viscosity.But in fact, the light constituent below this temperature, at 250-290 DEG C, can only be returned oil scrubber, have a large amount of low viscous component in the oil fuel of discharge by visbreaking tower tower top temperature, the efficiency of discharging pitch is low.Meanwhile, because quenching oil will contact with the ethane stove splitting gas of about 500 DEG C, at high temperature stop and add quenching oil studies on asphaltene growing amount, negative impact is caused to quenching oil viscosity.In actual motion, oil scrubber bottom temperature can only be limited in about 180 DEG C, just can control quenching oil viscosity.
Especially, cracking stock progressively lighting in recent years, because the Pyrolysis fuel oil PFO produced is little, under identical internal circulating load, output is less, and quenching oil residence time in system is longer, and the bituminous matter of generation is more, that can discharge is less, makes prior art substantially lose effect.Prior art is owing to cannot effectively discharge the bituminous matter generated in quenching oil, and the temperature that can only reduce oil scrubber tower reactor, to control quenching oil viscosity, considerably increases ethylene unit energy consumption.Therefore, be badly in need of a kind of technology of exploitation, while control quenching oil viscosity, improve quenching oil column bottom temperature, reduce ethylene unit comprehensive energy consumption.
Summary of the invention
For solving problems of the prior art, the invention provides a kind of method reducing ethylene unit energy consumption.Reclaimed by solvent extraction and step-down, reduce chilling oil viscosity, by improving oil scrubber bottom temperature to improve quenching oil temperature, and then increase dilution steam generation output, after being separated, solvent enters pyrolyzer cracking, reduces raw material preheating energy consumption, reduces the comprehensive energy consumption of ethylene unit.
The object of this invention is to provide a kind of above-mentioned method reducing ethylene unit energy consumption, it is characterized in that, the splitting gas that pyrolyzer outlet comes sends into oil scrubber after quencher cooling, carries out separating substances, at the bottom of oil scrubber tower, draw quenching oil, part quenching oil is sent to quencher; Part quenching oil returns oil scrubber; Part quenching oil enters extraction tower and carries out solvent extraction, and extraction tower materials at bottom of tower pitch is drawn mutually, and extraction tower tower top material isolates solvent and visbreaking quenching oil through the laggard solvent recovery tower of step-down, and visbreaking quenching oil returns oil scrubber, and solvent enters pyrolyzer cracking.
Oil scrubber bottom temperature of the present invention brings up to 190-250 DEG C, preferably brings up to 195-235 DEG C.
During extraction tower solvent extraction, the weight ratio of solvent and quenching oil is 0.01-20, is preferably 0.5-5; Extraction tower pressure is 0.5MPa-10MPa, and the temperature of extraction tower is 0 DEG C-250 DEG C.
Described solvent is selected from one in C2-C6 alkane, LPG, petroleum naphtha or its mixture, is preferably the one in C3-C5 alkane or its mixture.
Described quenching oil is the oil distillate of oil scrubber tower reactor in ethylene unit quenching system, and its typical composition is polycyclic aromatic hydrocarbons, colloid, bituminous matter.Described ethylene unit primarily of industrial pyrolysis furnace and chilling, compression, the System's composition such as to be separated, quenching system mainly comprises quencher, oil scrubber, water wash column.
The recovery tower pressure used during solvent recuperation is 0.1MPa-10Mpa, and temperature is 0 DEG C-250 DEG C.
Method of the present invention specifically can by the following technical solutions:
The high-temperature split product (containing the composition such as from H2 to Pyrolysis fuel oil PFO, also comprising dilution steam generation) of pyrolyzer outlet, enters quencher 4, directly contacts, cools with quenching oil after waste heat boiler reclaims heat and be cooled.Cooled split product enters oil scrubber 1 together with quenching oil, carries out gas-oil separation, and tower reactor draws quench oil circulated, enters Dilution steam generator 8, produces dilution steam generation.Improve quench oil circulated temperature by improving ethylene unit quenching system oil scrubber 1 bottom temperature mode, thus improve the generating capacity of dilution steam generation.
Be divided into three tunnels after quench oil circulated is cooled, pyrolyzer quencher 4 is removed on a road; One tunnel returns oil scrubber again through process water preheater 8, after topping-up pump 5 of leading up to pressurization, enters the quenching oil opening for feed of extraction tower 1.
Solvent enters the solvent feed mouth of extraction tower 2, solvent and quenching oil implement extracting in extraction tower 2, the extract oil (mixture of solvent and quenching oil light constituent) obtained is drawn from the extract oil outlet at extraction tower top, and the heeltap green grass or young crops of taking out obtained is drawn from the asphalt outlet bottom extraction tower.
Extract oil, after reducing valve 10 reduces pressure, through interchanger 7 raised temperature, enters solvent recovery tower 3 import.Extract oil is separated into solvent and visbreaking quenching oil in solvent recovery tower, and solvent is drawn from recovery tower tower top, and visbreaking quenching oil is drawn at the bottom of tower.
The solvent of being drawn by solvent recovery tower 3, as cracking stock, enters convection section in cracking furnace.
The visbreaking quenching oil of drawing from solvent recovery tower returns oil scrubber 1, thus effectively reduces overall quenching oil viscosity.
The present invention increases dilution steam generation steam exhaling amount by improving oil scrubber bottom temperature, quenching oil viscosity is reduced by solvent extraction and step-down desolventizing, and pass through the solvent after with separation for cracking stock minimizing raw material preheating energy consumption, improve ethylene unit heat recovery efficiency, reduce the energy consumption of ethylene unit.
Accompanying drawing explanation
Fig. 1 system schematic of the present invention
Description of reference numerals:
1 oil scrubber, 2 extraction towers, 3 solvent recovery towers, 4 quenchers, 5 topping-up pumps, 6 reducing valve, 7 pyrolyzer radiation sections, 8 Dilution steam generators, 9 preheaters
Embodiment
Below in conjunction with embodiment, further illustrate the present invention.
Embodiment:
200k/a produced per year by certain ethylene unit, and year runs 8000h, ethylene yield 25t/h.The Pintsch process gas (containing the composition such as from H2 to Pyrolysis fuel oil PFO, also comprising dilution steam generation) of pyrolyzer outlet, after waste heat boiler reclaims heat and be cooled, total amount is 147t/h, enters quencher, directly contacts, cools with quenching oil.Cooled splitting gas enters oil scrubber together with quenching oil, carries out gas-oil separation, and tower reactor draws quench oil circulated, enters Dilution steam generator, produces dilution steam generation.Be divided into three tunnels after quenching oil is cooled, pyrolyzer quencher is removed on a road; One tunnel returns oil scrubber again through process water preheater; Extraction tower is entered through solvent extraction in one tunnel, removes the heavy constituent 1.5t/h based on pitch bottom extraction tower, after the extract oil step-down that extracting tower top obtains, through well heater, then enters recovery tower, is separated into visbreaking quenching oil and solvent.Visbreaking quenching oil returns oil scrubber, reduces quenching oil viscosity.Solvent, as cracking stock, enters convection section in cracking furnace.Specific embodiment processing condition are as follows.
Comparative example
200kt produced per year by certain ethylene unit, year runs 8000h, ethylene yield 25t/h, and quenching system charging total amount is 140t/h, the quench oil circulated of drawing at the bottom of oil scrubber produces dilution steam generation by Dilution steam generator, then goes pyrolyzer quencher to return oil scrubber to after splitting gas cooling.Quenching oil viscosity 2000mm
2/ s, consume tempering oil 4t/h, oil scrubber bottom temperature is 178 DEG C, and generate dilution steam generation and only have 12t/h, ethylene unit energy consumption is up to 643GJ/h.
Claims (6)
1. reduce a method for ethylene unit energy consumption, it is characterized in that, the splitting gas that pyrolyzer outlet comes sends into oil scrubber after quencher cooling, carries out separating substances, and at the bottom of oil scrubber tower, draw quenching oil, part quenching oil is sent to quencher; Part quenching oil returns oil scrubber; Part quenching oil enters extraction tower and carries out solvent extraction, and extraction tower materials at bottom of tower pitch is drawn mutually, and extraction tower tower top material isolates solvent and visbreaking quenching oil through the laggard solvent recovery tower of step-down, and visbreaking quenching oil returns oil scrubber, and solvent enters pyrolyzer cracking.
2. the method reducing ethylene unit energy consumption as claimed in claim 1, it is characterized in that, oil scrubber bottom temperature is 190-250 DEG C, preferred 195-235 DEG C.
3. the as claimed in claim 1 method reducing ethylene unit energy consumption, is characterized in that, described solvent is selected from one in C2-C6 alkane, LPG, petroleum naphtha or its mixture, the one in preferred C3-C5 alkane or its mixture.
4. the method reducing ethylene unit energy consumption as claimed in claim 1, it is characterized in that, the weight ratio of the solvent and quenching oil that enter extraction tower is 0.01-20, preferred 0.5-5.
5. the method reducing ethylene unit energy consumption as claimed in claim 1, it is characterized in that, the pressure of described extraction tower is 0.5MPa-10MPa, and tower top temperature is 0 DEG C-250 DEG C.
6. the method reducing ethylene unit energy consumption as claimed in claim 1, it is characterized in that, the pressure of described solvent recovery tower is 0.1MPa-10Mpa.
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| CN201410542716.4A CN105567291B (en) | 2014-10-14 | 2014-10-14 | A kind of method for reducing ethylene unit energy consumption |
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Citations (4)
| 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 |
| CN103305259A (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 |
| CN103305258A (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 |
| CN103305260A (en) * | 2012-03-16 | 2013-09-18 | 中国石油化工股份有限公司 | System and 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 |
| CN103305259A (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 |
| CN103305258A (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 |
| CN103305260A (en) * | 2012-03-16 | 2013-09-18 | 中国石油化工股份有限公司 | System and method for reducing viscosity of quenching oil of ethylene unit |
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