CN105169888B - The modified technique and device of a kind of complete recycling of tail gas of polyethylene device - Google Patents
The modified technique and device of a kind of complete recycling of tail gas of polyethylene device Download PDFInfo
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Abstract
The invention discloses the modified technique of the complete recycling of tail gas of polyethylene device and device, modified technique comprises the following steps：A, the tail gas of polyethylene device for making to sequentially pass through high-low pressure cooling condensation recovery unit, coarse-fine filter element and Prepurification unit enter pressure-variable adsorption and separate upgrading unit, isolated hydrocarbon component and hydrogen nitrogen mixed gas；B, make hydrogen nitrogen mixed gas enter obtained after dehydrogenation unit, Dehydroepiandrosterone derivative purity up to more than 98% and hydrogen content be less than 1% nitrogen.Improve high-low pressure cooling condensation recovery unit, coarse-fine filter element, Prepurification unit, pressure-variable adsorption separation upgrading unit and dehydrogenation unit that device includes being sequentially connected with, tail gas of polyethylene device sequentially pass through high-low pressure cooling condensation recovery unit, coarse-fine filter element, Prepurification unit, pressure-variable adsorption separation upgrading unit and dehydrogenation unit reclaim obtain hydrocarbon component of the purity up to more than 90% and purity up to more than 98% and hydrogen content be less than 1% nitrogen.
Description
Technical field
The present invention relates to the tail gas recycle technical field of polyethylene production device, more particularly, it relates to a kind of
The modified technique and device of the complete recycling of tail gas of polyethylene device.
Background technology
In the production process of polyethylene, it will usually given off from polymer reactor and polyethylene powder degassing cabin a large amount of
By the hydrocarbon component including unpolymerized ethene and comonomer (propylene, butylene, hexene etc.) etc., induced condensing agent (isoamyl
Alkane, hexane etc.), the tail gas of polyethylene device mixed by the purging nitrogen of hydrogen and degassing cabin, its typical case's composition is such as the institute of table 1
Show.This partially polymerized tail gas generally drains into torch pipe network, causes the significant wastage of hydrocarbon resources, while also polluting environment.
The gases such as hydrocarbon component and nitrogen in recycle polyethylene tail gas, for polyethylene device it is energy-saving for it is significant.
Typical case's composition (mol%) of the tail gas of polyethylene device of table 1
| Ingredient names | H2 | N2 | CH4 | C2H4 | C2H6 | C4H8 | C5H12 |
| Content | 1~15 | 60~90 | 0~3 | 2.5~20 | 1~10 | 0~8 | 0~2 |
Hydrocarbon component in recycle polyethylene device exhaust has as the raw material of fuel or ethylene unit or Benzene Device
Very high economic benefit, if the nitrogen gas purity reclaimed is more than 95%, while hydrogen therein is less than 1%, then can return to degassing
Purge gass or circulating air are made in storehouse, this zero-emission for being also beneficial to environmental protection and realizing pollutant.
The method of existing recycle polyethylene tail gas generally includes the steps such as pressurization condensation, UF membrane and pressure-variable adsorption, from
And effective recovery of hydrocarbon component can be realized, wherein, the rate of recovery of hydrocarbon component can reach more than 99%.But, using existing
Have and contain more hydrogen in the nitrogen that the above method in technology reclaims, namely reclaim for hydrogen nitrogen mixed gas, if will reclaim
Hydrogen nitrogen mixed gas return directly to degassing cabin recycling, then may be formed in storehouse hydrogen accumulation and cause serious peace
Full hidden danger.
Therefore, needing offer badly a kind of can really make the modified technique and dress of the complete recycling of tail gas of polyethylene device
Put.
The content of the invention
For above-mentioned problems of the prior art and deficiency, it is an object of the invention to provide a kind of technological process letter
Single and energy recycle polyethylene tail gas completely and the modified technique and device that recycle.
To achieve these goals, an aspect of of the present present invention provides a kind of complete recycling of tail gas of polyethylene device
Modified technique, the modified technique comprises the following steps：
A, the polyethylene dress for making to sequentially pass through high-low pressure cooling condensation recovery unit, coarse-fine filter element and Prepurification unit
Put tail gas and separate upgrading unit, hydrocarbon component and hydrogen nitrogen mixed gas of the isolated purity up to more than 90% into pressure-variable adsorption；
B, enter the hydrogen nitrogen mixed gas to obtain purity after dehydrogenation unit, Dehydroepiandrosterone derivative up to more than 98% and hydrogen content
Nitrogen less than 1%.
According to one embodiment of the modified technique of the complete recycling of tail gas of polyethylene device of the present invention, the height
Low pressure cooling condensation recovery unit reclaims most of comonomer and induced condensing agent in the tail gas of polyethylene device, described
Coarse-fine filter element removes the solid particle and drop in the tail gas of polyethylene device, and the Prepurification unit removes described poly-
Micro alkyl aluminum in ethylene unit tail gas is to protect pressure-variable adsorption agent.
According to one embodiment of the modified technique of the complete recycling of tail gas of polyethylene device of the present invention, the change
Adsorbing separation upgrading unit is pressed to include the adsorption tower no less than 5, wherein, the adsorbent loaded in the adsorption tower is modified point
At least one of sub- sieve, modified silica-gel, modified activated carbon and modified aluminas.
According to one embodiment of the modified technique of the complete recycling of tail gas of polyethylene device of the present invention, the suction
The adsorbent loaded in attached tower is modified molecular screen, modified activated carbon, modified silica-gel and the modified oxygen being sequentially arranged from top to bottom
Change aluminium or the modified silica-gel, modified activated carbon and the modified aluminas that are sequentially arranged from top to bottom.
It is each to inhale according to one embodiment of the modified technique of the complete recycling of tail gas of polyethylene device of the present invention
Attached tower undergoes absorption, equal pressure drop, displacement, inverse put, evacuation, the circular treatment step that pressure rises and finally boosted successively, wherein, control
Make each adsorption tower different and ensure the suction that there is more than one at any time in the process step that synchronization is carried out
Attached tower carries out adsorption treatment step.
It is described de- according to one embodiment of the modified technique of the complete recycling of tail gas of polyethylene device of the present invention
Hydrogen unit is catalytic dehydrogenation unit or chemisorbed dehydrogenation unit.
According to one embodiment of the modified technique of the complete recycling of tail gas of polyethylene device of the present invention, the hydrocarbon
The rate of recovery >=99.9% of class component, the rate of recovery ＞ 99% of the nitrogen.
It is described another aspect provides a kind of improvement device of the complete recycling of tail gas of polyethylene device
The high-low pressure cooling that improving device includes being sequentially connected with by pipeline condense recovery unit, coarse-fine filter element, Prepurification unit,
Pressure-variable adsorption separates upgrading unit and dehydrogenation unit, wherein, the tail gas of polyethylene device sequentially passes through the high-low pressure cooling
Condensation recovery unit, coarse-fine filter element, Prepurification unit, pressure-variable adsorption separation upgrading unit and dehydrogenation unit reclaim and obtain pure
Spend up to more than 90% hydrocarbon component and purity up to more than 98% and hydrogen content be less than 1% nitrogen.
According to one embodiment of the improvement device of the complete recycling of tail gas of polyethylene device of the present invention, the change
Adsorbing separation upgrading unit is pressed to include the adsorption tower no less than 5, wherein, the adsorbent loaded in the adsorption tower is modified point
At least one of sub- sieve, modified silica-gel, modified activated carbon and modified aluminas.
According to one embodiment of the improvement device of the complete recycling of tail gas of polyethylene device of the present invention, the height
Low pressure cooling condensation recovery unit reclaims most of comonomer and induced condensing agent in the tail gas of polyethylene device, described
Coarse-fine filter element removes the solid particle and drop in the tail gas of polyethylene device, and the Prepurification unit removes described poly-
Micro alkyl aluminum in ethylene unit tail gas.
According to one embodiment of the improvement device of the complete recycling of tail gas of polyethylene device of the present invention, the suction
The adsorbent loaded in attached tower is modified molecular screen, modified activated carbon, modified silica-gel and the modified oxygen being sequentially arranged from top to bottom
Change aluminium or the modified silica-gel, modified activated carbon and the modified aluminas that are sequentially arranged from top to bottom.
According to one embodiment of the improvement device of the complete recycling of tail gas of polyethylene device of the present invention, the change
Pressure adsorbing separation upgrading unit also includes the sequence valve and surge tank being connected with the adsorption tower.
Invention introduces improved pressure swing adsorption technique and dehydrogenating technology so that the recovery process of tail gas of polyethylene device
It is simple and the complete recycling of tail gas of polyethylene device can be realized；Film separation unit is eliminated, is only separated by pressure-variable adsorption dense
Contracting unit reclaims the tail gas after high-low pressure condensation process, simplifies technological process, reduces investment and operating cost；Transformation is inhaled
Fufen is embodied in the improvement of adsorbent and technological process, improved adsorbent and type of feed pair from the process modification of upgrading unit
The larger comonomer of molecule and derivant selective absorption preferably, and just can be solved smoothly by being depressured to evacuate in a short time
Inhale, also can cancel pressure-changing process flow just because of this and rinse evacuation, only retain the step of evacuating, be conducive to further
Concentrate hydrocarbon component；Also, the dehydrogenating technology being introduced into can effectively remove the hydrogen being mixed with nitrogen, and then realize the complete of nitrogen
It is complete to recycle, it is to avoid potential safety hazard.Using technical scheme, the rate of recovery >=99.9% of hydrocarbon component can be realized
And purity >=90%, the rate of recovery ＞ 99% and purity >=98% and hydrogen content of nitrogen are less than 1%.
Brief description of the drawings
Fig. 1 shows the improvement dress of the complete recycling of tail gas of polyethylene device according to an exemplary embodiment of the present invention
The structured flowchart put.
Fig. 2 shows the improvement work of the complete recycling of tail gas of polyethylene device according to an exemplary embodiment of the present invention
The FB(flow block) of skill.
Embodiment
Hereinafter, it will be described in detail with reference to the accompanying drawings the improvement of the complete recycling of tail gas of polyethylene device of the present invention
Technique and device.Also, unless otherwise noted, percentage involved in the present invention is molar percentage.
According to the present invention, the tail gas of polyethylene device refers in the normal productive process of polyethylene from polymer reactor
With given off in polyethylene powder degassing cabin by including unpolymerized ethene and comonomer (propylene, butylene, hexene etc.) etc.
Hydrocarbon component, induced condensing agent (isopentane, hexane etc.), the gas mixed by the purging nitrogen of hydrogen and degassing cabin.
The improvement work of complete recycling can be carried out to tail gas of polyethylene device it is an object of the invention to provide a kind of
Skill and device, so as to comprehensively utilize or be used as the raw material or ethylbenzene of ethylene unit as fuel using the hydrocarbon component isolated
The raw material of device, while the hydrogen nitrogen mixed gas after concentrate can make nitrogen gas purity concentrate to more than 98% after dehydrogenation unit dehydrogenation
And hydrogen content is less than 1% and is recycled to polyethylene device recycling, thoroughly realizes the complete recycling of tail gas, reaches zero
Discharge.
The modified technique first to the complete recycling of tail gas of polyethylene device of the present invention is specifically described below.
Fig. 2 shows the improvement work of the complete recycling of tail gas of polyethylene device according to an exemplary embodiment of the present invention
The FB(flow block) of skill.As shown in Fig. 2 according to the present invention, the method bag of hydrocarbon component and nitrogen in the recycle polyethylene tail gas
Include following steps：A, the poly- second for making to sequentially pass through high-low pressure cooling condensation recovery unit, coarse-fine filter element and Prepurification unit
Alkene device exhaust enters pressure-variable adsorption and separates upgrading unit, and purity is respectively obtained after separation up to more than 90% hydrocarbon component and hydrogen
Nitrogen mixed gas；B, make the hydrogen nitrogen mixed gas enter obtained after dehydrogenation unit, Dehydroepiandrosterone derivative purity up to more than 98% and hydrogen contain
Nitrogen of the amount less than 1%.
In above-mentioned steps, tail gas of polyethylene device is first set to enter in pressure-variable adsorption separation upgrading unit, on the one hand can be with
Hydrogen nitrogen mixed gas is separated with hydrocarbon component, on the other hand can make hydrocarbon component and hydrogen nitrogen mixed gas concentrate, so as to be conducive to
The re-using of follow-up Dehydroepiandrosterone derivative and regenerant.According to a preferred embodiment of the invention, the hydrocarbon component is reclaimed and used
Make the raw material or the raw material of Benzene Device of fuel or ethylene unit, the nitrogen is back to the degassing cabin of polyethylene device as
Purge gass are used, and not only improve environmental protection, are also beneficial to realize the zero-emission of pollutant.
Wherein, most of copolymerization list that the high-low pressure cooling condensation recovery unit is used in recycle polyethylene device exhaust
Body and induced condensing agent, the coarse-fine filter element remove solid particle and drop in the tail gas of polyethylene device, described
Prepurification unit removes the micro alkyl aluminum in the tail gas of polyethylene device, wherein, activated carbon is filled with Prepurification unit.
High-low pressure cooling condensation recovery unit, coarse-fine filter element and Prepurification unit are equipment commonly used in the art, its structure and
Working method is herein without repeating.
The present invention's thes improvement is that the improvement of pressure swing adsorption technique and the introducing of De-hydrogen Technology, so that tail gas
Recovery process is simple and realizes recycling completely.Specifically, the pressure-variable adsorption separation upgrading unit used includes being no less than 5
Adsorption tower (specifically can according to the pressure change of tail gas of polyethylene device select varying number adsorption tower), certainly its may be used also
With including auxiliary equipments such as the sequence valve being connected with adsorption tower, surge tank, compressor, vavuum pumps.
Wherein, the present invention is improved on the sorbent, so that after high-low pressure cooling condensation recovery unit processing
Tail gas in the larger comonomer of the molecule that remains and induced condensing agent can obtain preferable selective absorption, and short
Just can smoothly it be desorbed in time by being depressured to evacuate.Specifically, the adsorbent loaded in the adsorption tower is modified molecular screen, changed
At least one of property silica gel, modified activated carbon and modified aluminas.Preferably, the adsorbent loaded in the adsorption tower be from
Modified molecular screen, modified activated carbon, modified silica-gel and modified aluminas that top to bottm is sequentially arranged or from top to bottom cloth successively
Modified silica-gel, modified activated carbon and the modified aluminas put, so that optimal adsorbing separation effect is realized, and this is also this hair
Bright technical scheme is different from prior art, i.e., enter pressure-variable adsorption again after a part of hydrocarbon component need not being reclaimed by UF membrane
The major reason of recovery.
According to the present invention, each adsorption tower undergoes absorption, equal pressure drop, displacement, inverse put, evacuation, pressure and risen and final successively
The circular treatment step of boosting, wherein, control each adsorption tower different and ensure in the process step that synchronization is carried out
The adsorption tower for having more than one at any time carries out adsorption treatment step.Namely, it is necessary to each adsorption tower is realized by control
Work with mutually staggering in time, so that device is continuously and stably run.Because the specific process step of adsorption tower is basis
What the pressure of tail gas of polyethylene device was specifically determined, operating personnel can for example increase according to the real-time set-up procedure of actual condition
Equal pressure drop, the number of times for pressing liter etc..
The adsorbent selected in the present invention can not only realize the selective absorption to hydrocarbon components such as ethene, ethane, also
Can be with binding molecule larger comonomer and induced condensing agent, and hydrogen nitrogen mixed gas is then from the gas vent row of absorption column overhead
Go out.Wherein, the reverse gas that obtains from adsorption tower entrance point and air is taken out for hydrocarbon component, some hydrocarbon component may serve as combustion
The raw material or Benzene Device raw material of material or ethylene unit, some hydrocarbon component then returns to adsorption tower and used as displacement gas, with this
Improve the purity of hydrocarbon component product.
Afterwards, the hydrogen nitrogen mixed gas separated from pressure-variable adsorption separation upgrading unit is entered dehydrogenation unit and carry out hydrogen
The removing of gas, thus obtain purity more than 98% nitrogen and hydrogen content be less than 1%.Wherein, dehydrogenation unit can be catalysis
Dehydrogenation unit and chemisorbed dehydrogenation unit.
The rate of recovery >=99.9% and purity >=90% of the hydrocarbon component obtained using the modified technique of the present invention, nitrogen
Rate of recovery ＞ 99%, purity >=98% and hydrogen content are less than 1%.
According to the exemplary embodiment of the present invention, the modified technique of the complete recycling of tail gas of polyethylene device
Idiographic flow is as follows：
1) tail gas of polyethylene device first passes around high-low pressure cooling condensation recovery unit and reclaims most of comonomer and lure
Lead and enter coarse-fine filter element after condensing agent.
2) filtering is removed after solid particle and drop into Prepurification unit in coarse-fine filter element.
3) removed in Prepurification unit and enter pressure-variable adsorption separation upgrading unit after micro alkyl aluminum.
Remaining hydrocarbon component, induced condensing agent and hydrogen in pressure-variable adsorption separates upgrading unit to tail gas of polyethylene device
Nitrogen mixed gas is separated and concentrated.
Pressure-swing adsorption concentration unit includes at least five adsorption towers, and every adsorption tower is in not experience absorption successively in the same time
(A), equal pressure drop (ED), displacement (RP), inverse put (D), the circular treatment step for evacuating (V), pressure liter (ER) and final boosting (FR)
Suddenly, it is specifically described below by taking the workflow of an adsorption tower as an example：
A, absorption (A)
Tail gas of polyethylene device enters hydrocarbon components most in adsorbent bed, tail gas from adsorption tower entrance point and inhaled
Attached, not to be adsorbed a large amount of H2、N2Etc. component, then as absorption waste gas, that to be hydrogen nitrogen mixed gas deliver to from the outlet discharge of adsorption tower is de-
Hydrogen unit.
B, equal pressure drop (ED)
After adsorption step stops, adsorption tower is set to connect with just completing the adsorption tower of evacuation step by pipeline and sequence valve
Row pressure is tapped into handle.At the end of pressing, the pressure of pressure liter and the adsorption tower of equal pressure drop is of substantially equal, reaches an intermediate pressure
Power.
C, displacement (RP)
In returning part hydrocarbon component to the adsorption tower for completing equal voltage drop step, specifically from the unstripped gas entrance of adsorption tower
End displacement valve enters adsorbent bed, ejects the hydrogen nitrogen mixed gas remained in adsorption tower using the higher hydrocarbon component of concentration and adsorbs
Tower, so as to improve the concentration of hydrocarbon component in adsorption tower.
D, inverse put (D)
Open complete displacement step adsorption tower unstripped gas arrival end inverse put valve, discharge adsorption tower in gas simultaneously
The pressure in adsorption tower is reduced, so that the hydrocarbon component desorption adsorbed on adsorbent, the hydrocarbon component after being separated.
E, evacuation (V)
Vavuum pump is evacuated to the adsorption tower after inverse put, further reduces adsorption column pressure, makes the hydro carbons on adsorbent
Component is further desorbed, and obtains hydrocarbon products gas.
F, boosting (ER)
After the completion of evacuation step, adsorption tower is set to be connected progress with the adsorption tower that absorption is completed by pipeline and sequence valve
Pressure is handled.At the end of pressing, pressure rises and the adsorption column pressure of equal pressure drop is of substantially equal, reaches an intermediate pressure.
G, final boosting (FR)
Hydrogen nitrogen mixed gas is returned to pressing liter adsorption tower completed to carry out pressurising, is allowed to substantially achieve adsorptive pressure, it is accurate
It is standby to enter next cycle period.
3) isolated hydrogen nitrogen mixed gas is sent into dehydrogenation unit and carries out Dehydroepiandrosterone derivative, obtain purity up to more than 98%
And hydrogen content is less than 1% nitrogen, nitrogen is back in degassing cabin and recycled.Wherein, dehydrogenation unit can be catalysis
Dehydrogenation unit or chemisorbed dehydrogenation unit.
4) isolated hydrocarbon component is used as to the unstripped gas of fuel or ethylene unit or Benzene Device.
Another aspect provides a kind of improvement device of the complete recycling of tail gas of polyethylene device.Fig. 1
Show the structural frames of the improvement device of the complete recycling of tail gas of polyethylene device according to an exemplary embodiment of the present invention
Figure.As shown in figure 1, the high-low pressure of the device including being sequentially connected with by pipeline that improve cools down condensation recovery unit, coarse-fine mistake
Unit, Prepurification unit, pressure-variable adsorption separation upgrading unit and dehydrogenation unit are filtered, wherein, the tail gas of polyethylene device is successively
By the high-low pressure cooling condensation recovery unit, coarse-fine filter element, Prepurification unit, pressure-variable adsorption separation upgrading unit and
Dehydrogenation unit reclaim obtain hydrocarbon component of the purity up to more than 90% and purity up to more than 98% and hydrogen content be less than 1% nitrogen
Gas.
In addition, the application method of said apparatus is similar with the concrete technology flow process of the inventive method, it will not be repeated here.
Below in conjunction with specific example to the present invention the complete recycling of tail gas of polyethylene device modified technique and
Device is further described.
Example 1：
The tail gas of polyethylene device 1000Nm of certain factory3/ h, pressure is 1.2MPa.The tail gas is reclaimed through high-low pressure cooling condensation
Gas composition as shown in table 2 is obtained after unit, coarse-fine filter element, Prepurification unit：
Certain the factory's tail gas of polyethylene device of table 2 is condensed, the composition (mol%) after filtering and preliminary clearning processing
| Component title | H2 | N2 | C2H4 | C2H6 | C4H8 | C5H12 |
| Content | 3.0 | 76.05 | 12.00 | 4.10 | 3.6 | 1.25 |
Then the gas shown in upgrading unit processing table 2 is separated using pressure-variable adsorption.Shown pressure-variable adsorption separator bag
6 adsorption towers, one group of surge tank and sequence valve etc. are included, the adsorbent loaded in adsorption tower is respectively from top to bottom modified point
Sub- sieve, modified activated carbon, modified silica-gel and modified aluminas.6 adsorption towers are respectively A towers, B towers, C towers, D towers, E towers and F towers,
The circulation each time of each adsorption tower is undergone absorption, 1 equal pressure drop, 2 equal pressure drops, displacement, inverse put, evacuation, pressed for 2 times successively
Rise, 1 pressure rises and nine steps of finally boosting.
Now by taking adsorption tower A as an example, illustrate the technical process of pressure-variable adsorption separation upgrading unit operation：
Adsorb (A)
The sequence valve of A tower inlet and outlets is opened, enters tail gas of polyethylene device exhausted big in adsorbent bed, gas
Some hydrocarbon component is adsorbed, a large amount of H not to be adsorbed2、N2Etc. component from adsorption column outlet discharge deliver to dehydrogenation unit.Work as suction
After the attached time arrives, the sequence valve of inlet and outlet is closed, the absorption of tail gas of polyethylene device is terminated.
1 equal pressure drop (E1D)
The pressure sequence valve of A towers and C towers is opened, the A towers after completion adsorption step is risen step with entering 2 pressures
C towers be connected, allow A towers gas enter C towers, then A pressure towers decline and C pressure towers rise, when the pressure of 2 towers is of substantially equal
When, sequence valve is pressed in closing, completes the equal voltage drop step of A towers.
2 equal pressure drops (E2D)
The pressure sequence valve of A towers and D towers is opened, makes the A towers after 1 equal voltage drop step of completion and completes evacuation step
Rapid D towers are connected, and allow A towers gas to enter D towers, then A pressure towers further decline and D pressure towers rise, when the pressure base of 2 towers
When this is equal, sequence valve is pressed in closing, completes 2 equal voltage drop steps of A towers.
Replace (RP)
Displacement gas import and the displacement waste gas outlet valve of A towers are opened, returning part hydrocarbon component enters from adsorption tower unstripped gas
Mouthful end displacement inlet valve, which enters, to be completed the A towers of 2 equal voltage drop steps and enters line replacement, using the higher hydrocarbon component of concentration by A towers
In the impurity such as hydrogen nitrogen mixed gas ejection adsorption tower, improve the concentration of hydrocarbon component in adsorption tower.After being arrived between when being replaced, close
A tower displacement gas imports and displacement waste gas outlet valve, terminate displacement.
Inverse put (D)
The inverse put sequence valve of A towers is opened, the A towers for completing displacement step is discharged adsorption tower against the direction of absorption
In gas, the hydrocarbon component that the pressure and making in reduction adsorption tower is adsorbed on adsorbent desorbs, the hydrocarbon component separated.
After A pressure towers are down to normal pressure, the inverse put sequence valve of A towers is closed, inverse put is completed.
Evacuate (V)
The evacuation sequence valve of A towers is opened, the A towers after inverse put are vacuumized by vavuum pump, further reduction
Adsorption column pressure, makes the hydrocarbon component on adsorbent further desorb, further obtains hydrocarbon component.When evacuation step is completed
Afterwards, the evacuation sequence valve of A towers is closed.
2 times pressure rises (E2R)
Sequence valve is pressed in open A towers and D towers 2 times, then the pressure that gas enters in A towers rise A towers in D towers is simultaneously returned
Receive the hydrocarbon component in D towers discharge gas.It is equal that A tower of the D towers for completing 2 equal voltage drop steps with completing evacuation step carries out pressure
Weighing apparatus, when two pressure towers are of substantially equal, closes the pressure sequence valve of A and D towers.
1 time pressure rises (E1R)
Sequence valve is pressed in open A towers and E towers 1 time, then the pressure that gas enters in A towers continuation rise A towers in E towers
And reclaim the hydrocarbon component in E towers discharge gas.The E towers and A towers progress pressure for completing 1 equal voltage drop step are balanced, treat two towers
When pressure is of substantially equal, the pressure sequence valve of A and E towers is closed.
Final boosting (FR)
The end for opening A towers fills valve, returns to hydrogen nitrogen mixed gas and carries out pressurising to the adsorption tower for completing pressure liter step, is allowed to base
Reach to close after adsorptive pressure on this and fill valve eventually, be prepared to enter into next cycle period.
So far, all steps of the A towers in a cycle are performed both by finishing and initially entered circulates next time.Other 5
Step performed by adsorption tower is identical with A towers, simply mutually staggers in time, to ensure that separation process is carried out continuously.Each
The pressure of adsorption tower is in cyclically-varying with the change of processing step.
Collect and separate the isolated hydrocarbon component of upgrading unit through the pressure-variable adsorption, and isolated hydrogen nitrogen is mixed
Close pneumatic transmission to enter to carry out Dehydroepiandrosterone derivative in chemisorbed dehydrogenation unit, obtain nitrogen.By the hydrocarbon component be recycled as fuel or
The raw material of ethylene unit or the raw material of Benzene Device, the degassing cabin that the nitrogen is back into polyethylene device make as purge gass
With.
The main composition (mol%) for obtaining nitrogen is reclaimed in the example 1 of table 3
| Component | H2 | N2 | C2H4 | C2H6 | C4 + |
| Content | 0.8 | 98.5 | 0.39 | 0.28 | 0.03 |
The main composition (mol%) for obtaining hydrocarbon component is reclaimed in the example 1 of table 4
| Component | H2 | N2 | C2H4 | C2H6 | C4 + |
| Content | ---- | 6.8 | 34.84 | 40.89 | 17.47 |
Table 3 and table 4 show that example 1 reclaims the main composition of obtained nitrogen and hydrocarbon component, wherein, the flow of nitrogen
Purity up to more than 98% and hydrogen content be less than 1%, and hydrocarbon component purity up to more than 90% and wherein contain substantial amounts of second
The hydrocarbon-rich gas such as alkene and ethane.
In summary, invention introduces improved pressure swing adsorption technique and dehydrogenating technology so that tail gas of polyethylene device
Recovery process it is simple and the complete recycling of tail gas of polyethylene device can be realized；Film separation unit is eliminated, only passes through transformation
Adsorbing separation upgrading unit reclaims the tail gas after high-low pressure condensation process, simplifies technological process, reduces investment and runs
Cost；Flushing is eliminated in process step in pressure-variable adsorption separation upgrading unit to evacuate, and is only retained the step of evacuating, is conducive to
Further concentrate hydrocarbon component；Also, the dehydrogenating technology being introduced into can effectively remove the hydrogen being mixed with nitrogen, and then realize nitrogen
The complete recycling of gas, it is to avoid potential safety hazard.Using technical scheme, can realize the rate of recovery of hydrocarbon component >=
99.9% and purity >=90%, rate of recovery ＞ 99%, purity >=98% and the hydrogen content of nitrogen are less than 1%.
Although combined exemplary embodiment describes tail gas of polyethylene device of the invention and reclaims again sharp completely above
Modified technique and device, but it should be clear to those skilled in the art that do not departing from the spirit and model of claim
In the case of enclosing, various modifications and variations can be carried out to above-described embodiment.
Claims (7)
1. a kind of modified technique of the complete recycling of tail gas of polyethylene device, it is characterised in that the modified technique includes
Following steps：
A, the polyethylene device tail for making to sequentially pass through high-low pressure cooling condensation recovery unit, coarse-fine filter element and Prepurification unit
Gas enters pressure-variable adsorption and separates upgrading unit, hydrocarbon component and hydrogen nitrogen mixed gas of the isolated purity up to more than 90%, wherein,
The adsorbent that the pressure-variable adsorption separation upgrading unit includes loading in the adsorption tower no less than 5, the adsorption tower is from upper
The modified molecular screen, modified activated carbon, modified silica-gel and the modified aluminas that are sequentially arranged under are sequentially arranged from top to bottom
Modified silica-gel, modified activated carbon and modified aluminas；
B, make the hydrogen nitrogen mixed gas enter obtained after dehydrogenation unit, Dehydroepiandrosterone derivative purity up to more than 98% and hydrogen content be less than
1% nitrogen.
2. the modified technique of the complete recycling of tail gas of polyethylene device according to claim 1, it is characterised in that institute
The most of comonomer and induced condensing agent in the high-low pressure cooling condensation recovery unit recovery tail gas of polyethylene device are stated,
The coarse-fine filter element removes solid particle and drop in the tail gas of polyethylene device, and the Prepurification unit removes institute
State the micro alkyl aluminum in tail gas of polyethylene device.
3. the modified technique of the complete recycling of tail gas of polyethylene device according to claim 1, it is characterised in that every
Individual adsorption tower undergoes absorption, equal pressure drop, displacement, inverse put, evacuation, the circular treatment step that pressure rises and finally boosted successively, its
In, control each adsorption tower different and ensure there is more than one at any time in the process step that synchronization is carried out
Adsorption tower carry out adsorption treatment step.
4. the modified technique of the complete recycling of tail gas of polyethylene device according to claim 1, it is characterised in that institute
Dehydrogenation unit is stated for catalytic dehydrogenation unit or chemisorbed dehydrogenation unit.
5. the modified technique of the complete recycling of tail gas of polyethylene device according to claim 1, it is characterised in that institute
State the rate of recovery >=99.9% of hydrocarbon component, the rate of recovery ＞ 99% of the nitrogen.
6. a kind of improvement device of the complete recycling of tail gas of polyethylene device, it is characterised in that the improvement device includes
High-low pressure cooling condensation recovery unit, coarse-fine filter element, Prepurification unit, the pressure-variable adsorption being sequentially connected with by pipeline are separated
Upgrading unit and dehydrogenation unit, wherein, the tail gas of polyethylene device sequentially pass through high-low pressure cooling condensation recovery unit,
Coarse-fine filter element, Prepurification unit, pressure-variable adsorption separation upgrading unit and dehydrogenation unit reclaim and obtain purity up to more than 90%
Hydrocarbon component and purity up to more than 98% and hydrogen content be less than 1% nitrogen, wherein, pressure-variable adsorption separation concentration is single
The adsorbent that member includes loading in the adsorption tower no less than 5, the adsorption tower is the modified molecules being sequentially arranged from top to bottom
Sieve, modified activated carbon, modified silica-gel and modified aluminas or the modified silica-gel being sequentially arranged from top to bottom, modified activated carbon and
Modified aluminas.
7. the improvement device of the complete recycling of tail gas of polyethylene device according to claim 6, it is characterised in that institute
The most of comonomer and induced condensing agent in the high-low pressure cooling condensation recovery unit recovery tail gas of polyethylene device are stated,
The coarse-fine filter element removes solid particle and drop in the tail gas of polyethylene device, and the Prepurification unit removes institute
State the micro alkyl aluminum in tail gas of polyethylene device.
Priority Applications (1)
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| CN106975322B (en) * | 2017-03-09 | 2019-10-25 | 中石油北方工程设计有限公司 | A kind of exhaust gas processing device and processing method |
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| CN101530711B (en) * | 2009-04-14 | 2011-12-21 | 中国石油化工股份有限公司 | Method for completely reclaiming tail gas of polyethylene device |
| CN104043315B (en) * | 2014-05-23 | 2016-06-01 | 四川天采科技有限责任公司 | The method of a kind of recover hydrogen, ethene from high low pressure oil refinery dry gas |
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Address after: High tech Zone Gaopeng road in Chengdu city of Sichuan province 610041 No. 5 Chengdu hi tech Zone Innovation Service Center Patentee after: Haohua Chemical Technology Group Co.,Ltd. Address before: No. 5 high tech Zone Gaopeng road in Chengdu city of Sichuan Province in 610041 Patentee before: SICHUAN TIANYI SCIENCE AND TECHNOLOGY Co.,Ltd. |
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Effective date of registration: 20200423 Address after: No. 5 high tech Zone Gaopeng road in Chengdu city of Sichuan Province in 610041 Patentee after: SOUTHWEST RESEARCH & DESIGN INSTITUTE OF CHEMICAL INDUSTRY Address before: High tech Zone Gaopeng road in Chengdu city of Sichuan province 610041 No. 5 Chengdu hi tech Zone Innovation Service Center Patentee before: Haohua Chemical Technology Group Co.,Ltd. |