CN102502498B - Method for separating and recovering chlorine and oxygen of hydrogen chloride oxidation gas mixture by use of PSA (Pressure Swing Adsorption) technology - Google Patents
Method for separating and recovering chlorine and oxygen of hydrogen chloride oxidation gas mixture by use of PSA (Pressure Swing Adsorption) technology Download PDFInfo
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Abstract
The invention relates to a method for separating and recovering chlorine and oxygen of a hydrogen chloride oxidation gas mixture by use of a PSA (Pressure Swing Adsorption) technology and belongs to the technical field of gas separation. The method aims at a gas mixture generated by catalytic oxidation of hydrogen chloride and comprises the following steps of: firstly absorbing unreacted hydrogen chloride with water, dehydrating through concentrated sulfuric acid, and introducing a residual gas mixture into a PSA device so as to be separated, wherein the PSA device comprises at least two absorbing tower units, adsorbents filled in the absorbing tower units are at least one of silica gel and active carbon, and the volume proportion of the active carbon is 0-50%; chlorine with the purity of more than 99.2% is obtained after adsorption, pressure equalizing, flushing and desorption steps are carried out on the gas mixture, adsorption tail gas is oxygen with the purity of more than 99.5%, and the recovery rates of chlorine and oxygen are more than 98.5%. The method for separating and recovering the chlorine and oxygen of the hydrogen chloride oxidation gas mixture by the PSA technology, disclosed by the invention, is especially suitable for separation recovery of the chlorine and oxygen of the hydrogen chloride oxidation gas mixture, and has the advantages of simple process, high recovery rates and purities of chlorine and oxygen, and excellent economical and environmental-friendly benefits.
Description
Technical field
The present invention relates to the method for the separated chlorine of chemical field and oxygen, be specifically related to a kind of method of utilizing pressure swing adsorption method (PSA) Selective Separation and reclaim chlorine and oxygen from chloration hydro-oxidation mist.
Background technology
Along with the development of Chinese national economy, many chloride industry have become the important component part of national economy, and its development has driven the wilderness demand to chlorine, and the imbalance between supply and demand of the in great demand and undersupply of chlorine has just appearred in some areas; Industrial most chlorine all obtains from chlorine industry, the simple scale that expands chlorine industry that relies on can cause the contradiction of chlor-alkali balance again, along with the operation of project begun newly and the continuous release of production capacity, when meeting the demand of chlorine, caustic soda is excessive, China is that minority needs a large amount of import chlorine products, but exports the country of caustic soda simultaneously; In general organic chlorination, a chlorine atom replaces a hydrogen atom effectively to be used, and another chlorine atom generates so-called byproduct hydrogen chloride in conjunction with this hydrogen atom, and such 50% chlorine is with the form output of byproduct hydrogen chloride.The processing of by-product hydrogen chloride is a difficult problem always, and use and by-product become again conflict like this, use manyly, and by-product amount is also just larger, and contradiction is more serious.Polyurethane MDI/TDI, PTFE, Mannheim proeess are produced the production processes such as potassium sulfate, methane chloride, expoxy propane, and by-product hydrogen chloride that all can be a large amount of in the production process of monoxone, chlorinated paraffin wax, dimethylphosphite.In the production of Mannheim proeess potassium sulfate, often obtain 1 ton of target product, will increase by 0.4 ton of by-product HCl.In the production of dimethylphosphite, this value is 0.66 ton in theory.Cold-producing medium is produced with hydrogen fluoride and chloroform substitution reaction, and producing 100000 tons of devices per year just has the by-product HCl of 6～70,000 tons/year.The primary raw material of polyurethane is MDI ('-diphenylmethane diisocyanate) and TDI (toluene di-isocyanate(TDI)).Polyurethane and basic material thereof have become after polyvinyl chloride, and another consumes the more chemical products of chlorine.Within 2010, world's polyurethane products total output reaches 1,700 ten thousand tons, and Chinese polyurethane output 2009 is close on 4000000 tons.Within 2010, global TDI has the production capacity of 2,300,000 tons, 190.9 ten thousand tons of demands, and the production capacity of MDI will reach 4,880,000 tons, and demand has 418.8 ten thousand tons.The production capacity that China expects MDI in 2017 will reach 1,400,000 tons.When chlorine demand and use amount increase day by day, the output of by-product hydrogen chloride also increases year by year.As far back as America and Europe in 1999 10 million ton/year, and the demand gap of chlorine just continues to increase.Also the have an appointment by-product hydrogen chloride of 60,000 t/a of the MDI device of 100000 t/a.Also the have an appointment by-product hydrogen chloride of 8.39 ten thousand t/a of the TDI device of 100000 t/a.Therefore, need badly and find a kind of economic and practical hydrogen chloride preparing chlorine gas technology, realize closed cycle and the zero-emission of chlorine element, both for by-product hydrogen chloride finds a way out, solved again the problems such as chlor-alkali balance that many areas exist.
The method of hydrogen chloride preparing chlorine gas mainly contains electrolysis, inorganic oxidizer direct oxidation method and air/oxygen catalytic oxidation (being Deacon process).Conventional electrolysis preparing chlorine gas energy consumption is too high, and the shortcoming of inorganic oxidizer direct oxidation method is that comparison in equipment is complicated, product separation difficulty, and energy consumption is too high.Deacon process is under the condition of the oxide of Cu, Ru, Cr etc. or oxide catalyst existence, at 300～550 ℃ of oxygen of high temperature, directly hydrogen chloride gas is oxidized to chlorine.It is generally acknowledged that Deacon process is as follows:
2HCL+1/2O
2→CL
2+H
2O ΔH＝-13.8kcal/mol
This technology is because the problems such as conventional catalyst activity is low, the life-span is short and reactor design difficulty large, the pure energy consumption height of subsequent product air lift restrict large-scale industrialization always.At present domesticly developed catalyst for catalytic oxidation and designed the fluidized-bed reactor more suitable to catalytic oxidation process, a difficult problem that realizes the industrialization maximum of catalytic oxidation of hydrogen chloride for preparing chlorine gas technology is how to reduce the separating energy consumption of subsequent product gas.Due to can not aerobic and water in photochemical system, so, within TDI production process, in various raw material components, oxygen content and water content are all controlled at quite strict scope.At present, TDI industry is generally 0 by the quality index of chlorine
2≤ 100ppm; H
2o≤100ppm.
Hydrogen chloride, by catalytic oxidation, contains chlorine, hydrogen chloride, oxygen G&W in reacted gaseous mixture.Mist passes through water absorbing hydrogen chloride, then removes after water by the concentrated sulfuric acid, substantially only has chlorine and oxygen in gaseous mixture.Current separated chlorine and oxygen common method mainly contain pressure swing adsorption method, condensation method, cryogenic rectification method, absorption-desorption method and membrane separation process etc.Pressure swing adsorption method basic principle is to utilize different adsorbates in uniform temperature, adsorption rate under different pressures condition on solid absorbent, absorption affinity, the difference of adsorbance is achieved the separation between each adsorbate, it is simple that this technology has technique, investment and operating cost are low, automaticity is high, product purity is high, stop car convenient, the features such as energy consumption is low, making oxygen by air separation and nitrogen processed since the eighties in 20th century, have been successfully applied to, synthetic ammonia relief gas hydrogen reclaims, natural gas purification, oven gas decarburization, oil refinery dry gas olefin recovery, the numerous areas such as device in Gas methane recovery.In conventional pressure swing adsorption technique process, the cycling process of each adsorption tower unit generally comprises absorption (A), the equal pressure drop of one or many (ED), along putting (P) or inverse put (D), slow rinse (C), vacuumizing the steps such as (V), the equal voltage rise of one or many (ER), whole pressurising (FR).
Chinese patent literature CN90110412.4 discloses a kind of method for concentration of chlorine, and the method adopts pressure swing adsorption will contain the carbon dioxide (or nitrogen) of 5～15% chlorine and gaseous mixture concentrate to 55～83% of helium.CN200680005928.2 discloses a kind of method of preparing chlorine, and this method utilizes the method that condensation method and membrane separation process combine to reclaim the chlorine in the catalytic oxidation of hydrogen chloride gaseous mixture, and product purity of chlorine gas feeding is greater than 95 (wt) %.Chinese patent 201010194714.2 discloses a kind of method that reduces oxygen content of circulating chlorine gas, and it adopts high temeperature chemistry reducing process to reduce the oxygen content in circulating chlorine gas.US Patent No. 33995387 (A) discloses a kind of with CCl
4for the method that the absorption-desorption method of absorbent is produced liquid chlorine, US5308383 discloses a kind of with C
7f
3h
4-ncl
n(n=1～3) are the chlorine absorption reuse method of absorbent.Chinese patent CN200510025910.6 discloses a kind of process for separation and purification that contains chlorine and hydrogen chloride mix waste gas, and this method adopts absorption process to obtain product purity of chlorine gas feeding can reach 99%.Chinese patent 200780018846.6 is being used the thermal response of catalyst condition and/or by the non-thermal priming reaction of hydrogen chloride and oxygen, is being prepared the method for chlorine by hydrogen chloride and oxygen, wherein a) that the admixture of gas generating in reaction is cooling so that salt acid condensation, this admixture of gas is at least by target product chlorine G&W, unreacted hydrogen chloride and oxygen, and other accessory constituent, for example carbon dioxide and nitrogen and optional phosgene, form, b) the liquid hydrochloric acid of resulting separation from remaining admixture of gas, c) remove remaining residual water in separated admixture of gas, particularly by washing with the concentrated sulfuric acid, it is characterized in that d) pass through gas permeation, from resulting chlorine-containing gas mixture, remove oxygen and optional other accessory constituent, particularly carbon dioxide and/or nitrogen and/or phosgene.Preferably use and carry out according to the film of molecular sieve principle operation, this gas permeation is preferably used so-called carbon film to carry out.Known carbon film consists of pyrolyzed-polymer, for example, be selected from the pyrolyzed-polymer of organizing below: phenolic resins, furfuryl alcohol, cellulose, polyacrylonitrile and poly-phthalimide.
In above-mentioned each patented method, the product purity of chlorine gas feeding that pressure swing adsorption method obtains is not high, can not meet the requirement that Chemical Manufacture is greater than 99% by purity of chlorine gas feeding.Though adopt condensation method, absorption process, low temperature distillation method, membrane separation process and coupled method thereof can reach purity requirement, but energy consumption is high, complex process, is unfavorable for that national energy-saving reduces discharging, the enforcement of the strategy of sustainable development.
In electrolysis situation, first hydrogen chloride change into aqueous hydrochloric acid, is then electrolyzed to produce chlorine and hydrogen, and chlorine obtains with the form concentrating.In another kind Deacon (Deacon) the processed chlorine method more energy-conservation than electrolytic method, hydrogen chloride is changed into chlorine, oxygen, water, only can obtain chlorinity is rare chlorine logistics of 10～50% (volumes).This rare chlorine logistics must obtain with the form concentrating through post processing, and this is because Chemical Manufacture requires purity higher than 99% high-purity dry chlorine gas.The Shell-Deacon method (The Chemical Engineer, (1963) 224-232) of HCL oxidation is by absorption-desorption method CCL
4as absorbent, isolate chlorine.In absorption tower, under the tower top temperature of about 0.15MPa and approximately 11 ℃, from chlorine content, be 27～48% (also containing N
2, O
2and CO
2) feeding gas in wash out chlorine.The process that discharges chlorine from absorption liquid is to be in desorber, to carry out under approximately 65.5 ℃, the pressure condition that is about 1.1MPa in tower top temperature, and the chlorine discharging is purified by partial condensation in adding the water condenser of depressing, installing at top.Uncooled chlorine and other gas components that are still present in wherein turn back to absorption tower.EP-A0518553 has described first with carrying out separated chlorine by Vacuum Pressure Swing Adsorption (Vaculmm pressure swing adsorption) after low temperature distillation tower.By feed gas compression and first use without chlorine exit gas coolingly, be then passed into condensation or low temperature distillation tower, the form that part chlorine can neat liquid in this tower is discharged from the bottom of tower.Remaining chlorine-containing gas leaves tower through tower top, then enters Vacuum Pressure Swing Adsorption (VPSA) tower.In adsorption tower, about 0.4～1.1MPa and 0～150 ℃, preferred at room temperature the hocket absorption and separation of chlorine and residual gas.By the Vacuum Pressure Swing Adsorption of 1～60 kPa of continuous application, from adsorption tower, obtained the chlorine of high concentration, after the chlorine desorb of absorption, these adsorption towers can be reused for charging.Spendable absorbent is synthetic or natural zeolite or nonzeolite porous oxide, preferably carbon back absorbent, for example active carbon and carbon molecular sieve.Yet it is all highly purified chlorine that the method is not suitable for obtaining from feed gas, because the gas phase existing in adsorption tower still contains all gas component of gas stream, therefore, not only chlorine is absorbed, and other gas components are also partially absorbed simultaneously.When adopting vacuum, enter the chlorine logistics of discharging from adsorption tower together with the chlorine of these components and absorption.The chlorine only obtaining from condensation/cryogenic separation section is only pure.Yet, owing to having limited technically and economically chilling temperature, so the amount of chlorine is only a limited part, this depends on the chlorine gas concentration in feed gas, in order to obtain it being all pure chlorine from VPSA, isolated chlorine must pass through further purification step.Therefore, add the shortcoming of condensation/low temperature distillation step to be before VPSA, chloride feed gas stream must be compressed to high chlorine condensing pressure (0.5～1MPa), and must be cooled to corresponding chlorine condensation temperature.Chinese invention patent ZL200410048809.8 disclosed a kind of from admixture of gas Selective Separation and reclaim the method for chlorine, first the method carries out chlorine-containing gas logistics Vacuum Pressure Swing Adsorption (VPSA), chlorine-containing gas from Vacuum Pressure Swing Adsorption (VPSA) is compressed to 0.5～1MPa, then carry out low temperature distillation, isolate the pure chlorine as the tower bottom product of destilling tower, the overhead product of destilling tower is turned back in the feed gas stream of Vacuum Pressure Swing Adsorption (VPSA).
The object of the invention is to improve the above-mentioned method of isolating highly purified chlorine from chlorine-containing gas logistics, and be optimized aspect energy-saving and emission-reduction, consumption reduction, this method can be carried out with minimum device, separated by pressure-variable adsorption, oxygen in absorption tail gas also purifies to more than 99.5%, substantially there is no chlorine, the chlorine content in stripping gas reaches more than 99.2%, and chlorine Content Test standard adopts GB5138-2006.The two rate of recovery can reach more than 98.5%.Oxygen after purification can return to the catalytic oxidation of hydrogen chloride unit as oxygen source utilization, really realizes the maximum using of resource.
Summary of the invention
In the gaseous mixture producing after the catalytic oxidation of hydrogen chloride, mainly contain chlorine, complete hydrogen chloride, the oxygen G&W of unreacted.Before this gaseous mixture enters pressure-swing absorption apparatus, need to carry out pretreatment to remove hydrogen chloride and the water in gaseous mixture, the mode that specifically removes is: first utilize hydrogen chloride characteristic soluble in water, gaseous mixture is absorbed except de-chlorine hydride by water; Then by gaseous mixture by the drying tower of the concentrated sulfuric acid is housed, make reduced water content in gaseous mixture to 200ppm.Gaseous mixture enters from absorption tower T1 bottom Side mouth, at T1 top, absorption tower bubble column spray, inject appropriate water simultaneously, in absorption tower T1 bottom packed tower and top bubble column, the hydrogen chloride water in the gaseous mixture of rising is carried out to blended absorbent, T1 bottom in absorption tower connects salt acid circulating pump P1 and returns to packed tower top formation closed circuit, the hydrochloric acid that makes blended absorbent in filler again with the gaseous mixture rising in the hydrogen chloride absorption enrichment that circulate, when reaching, concentration of hydrochloric acid sets after index, beginning is by absorption tower T1 bottom extraction hydrochloric acid, not yet absorbed hydrogen chloride rises in the bubble column of top and all absorbs.Gaseous mixture enters from concentrated sulfuric acid drying tower T2 bottom Side mouth, at inner-tower filling material, soak the full concentrated sulfuric acid simultaneously, moisture content in the gaseous mixture rising carries out blended absorbent with the concentrated sulfuric acid, moisture content in gaseous mixture rises to tower top and is all absorbed, the concentrated sulfuric acid is diluted gradually, when sulfuric acid concentration dilution reaches, set after index, start, by drying tower T2 bottom extraction dilute sulfuric acid, to refill the appropriate concentrated sulfuric acid.
After aforementioned pretreatment unit, in gaseous mixture, substantially only contain chlorine and oxygen, then by the mode of pressure-variable adsorption, the two is carried out to separation and reclaim.Pressure-swing absorption apparatus of the present invention comprises at least two adsorption tower unit, and each adsorption tower unit obtains product chlorine through adsorbing, all press, rinse, vacuumize the steps such as regeneration successively, and wherein absorption tail gas is product oxygen.The key of pressure swing adsorption method is adsorbent, the adsorbent that the present invention uses is at least one in silica gel and active carbon, in the material mixed gas producing according to front end the catalytic oxidation of hydrogen chloride technique, the content of chlorine and oxygen is different, the filling ratio of active carbon is 0～50% (weight ratio), while using at the same time silica gel and active carbon, its type of feed is that active carbon is placed in adsorption tower lower end, and silica gel is placed in adsorption tower upper end.The arrangement that can rationally increase and decrease each step and respectively walk order according to adsorbent characterization of adsorption, purity of product gas and yield requirement etc., to reach continuous, the energy consumption minimized object of technique.Pressure swing adsorption technique process of the present invention is comprised of at least 2 adsorption tower unit, and each adsorption tower unit all needs through aforementioned each cycling process.Concrete technical process is as follows:
Pressure-variable adsorption adopts 4-1-2 flow process, and device is comprised of four adsorption towers, an equalizer tank and a vavuum pump, and before entering pressure-variable adsorption, chloration hydro-oxidation gaseous mixture removes device and drying device processing through hydrogen chloride.In four adsorption towers, adsorption tower different phase in absorption wherein, an adsorption tower is in vacuumizing regenerative process, another two adsorption towers are in all pressing and the suitable journey of letting slip, in whole separation process, technical process experienced absorption, twice drop pressure, along putting, replace, vacuumize, nine steps such as twice boost pressure and product oxygen pressure rising.
The detailed process of each step is as follows:
A. adsorption process
Contain the unstripped gas of chlorine and oxygen after heat exchange, temperature constant directly enters from the bottom of adsorption tower after certain value, and wherein chlorine is adsorbed onto on Special adsorbent entirely, and the oxygen not being adsorbed etc. can be smoothly by the adsorbent bed battery limit (BL) of sending.
B. drop pressure process
This process is along absorption direction, the gas of adsorption tower is carried out to drop pressure by all pressing with the adsorption tower of another boost pressure, this process is all to another adsorption tower by the component oxygen that is difficult for absorption in adsorption tower, reduce gradually on the one hand the pressure of adsorption tower, meet the condition of adsorption tower desorption and regeneration, reclaim on the other hand the interior a small amount of chlorine of dead space in adsorption tower.
According to practical operation pressure condition, it all presses number of times can be once, can be also twice even more times.Originally be stated as twice.
C. along putting decompression process
Complete after pressure equalizing, along absorption direction, the pressure of adsorption tower is reduced gradually, the chlorine being now adsorbed on adsorbent starts desorb again, the chlorine of separating sucking-off is full of whole adsorption tower dead space gradually, makes the purity of chlorine gas feeding that stops and be adsorbed reach required value as far as possible.
Along the gas containing part chlorine of emitting, after pressurization, turn back to native system unstripped gas entrance.
D. replacement process
Along letting slip after journey, then adsorption tower is replaced with a small amount of chlorine along the direction of absorption, replacement of oxygen a small amount of in adsorption tower headroom is gone out to adsorption tower, improve chlorine gas concentration in adsorption tower.
If the chlorine gas concentration requiring is not high especially, also can replaces, and directly to the adsorption tower desorb of regenerating, reclaim chlorine wherein.
Displacement gas also returns to feed(raw material)inlet compressor, and recovery capable of circulation is chlorine wherein.
E. vacuum desorption process
After completing and forward bleeding off pressure and replace, gas component in adsorption tower is mainly chlorine, gas concentration is more than 99%, now adopt the mode vacuumizing, make the chlorine of absorption in adsorption tower be able to desorb under vacuum state, separate the product chlorine that the gas of sucking-off is recovery, after surge tank buffering, send battery limit (BL).
F. boost pressure process
Boost pressure is corresponding with drop pressure, the pressure of adsorption tower gradually raises on the one hand, for absorption next time is prepared, reclaim on the other hand a small amount of chlorine in another adsorption tower step-down process, device can be still once all to press according to the pressure condition of unstripped gas, also twice even more times, this narration is all compressed into line description by twice.
G. the product oxygen process of finally boosting
In vacuum regeneration process, complete, and after all pressing, for adsorption tower can be switched in the process of adsorbing reposefully next time, pressure oscillation does not occur, need to adsorption column pressure be risen to adsorptive pressure with the oxygen of separating.This process not only makes adsorption tower boost, for absorption next time is prepared, simultaneously also with respect to the process to a flushing at adsorption tower outlet position, a small amount of chlorine of absorption in the adsorbent of adsorption tower exit position is moved to adsorption tower arrival end, and while guaranteeing next time adsorbing separation, oxygen purity arrives requirement.
After this process, adsorption tower has just completed complete " adsorption-regeneration " circulation, again for absorption is next time got ready.Four adsorption towers said process that hockets, reaches the object of continous-stable oxygen separation and chlorine.The feature of pressure-variable adsorption is many adsorption towers, can in separation process, all press can be once from two to more than ten adsorption towers, also even repeatedly all presses for twice.The absorption absorption of can connecting, also can non-series connection absorption.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of feed gas preprocessing, pressure-variable adsorption operation.
Code name explanation in figure: P1-salt acid circulating pump, T1-absorption tower, T2-concentrated sulfuric acid drying tower, P2-vavuum pump, V1-equalizer tank, tetra-adsorption towers of T3a～T3d-.
Compared with prior art, the present invention has the following advantages:
The present invention can effectively reclaim the chlorine in chloration hydro-oxidation gaseous mixture and oxygen separation, and wherein the adsorption tower port of export obtains highly purified oxygen, vacuumizes and obtains highly purified chlorine.The gas product oxygen obtaining can return to the catalytic oxidation of hydrogen chloride cell arrangement recycling, and it is synthetic that gas product chlorine can be directly used in phosgene.The present invention will be further described for the specific embodiment by the following examples, but context of the present invention is not only confined to following specific embodiment.
The specific embodiment
Under normal temperature and pressure, chlorine and oxygen enter series connection adsorption tower by air glass rotameter with the ratio of 7: 3 at the bottom of adsorption tower.This unstripped gas is chlorine and the remaining oxygen of oxidation after chloration hydro-oxidation, and it consists of: 70% chlorine, and 30% oxygen, pressure is 0.3MPa, water content is below 200ppm.For the component characteristic of unstripped gas, can select certain specific adsorbent, chlorine wherein is fully adsorbed, obtain the oxygen that purity is greater than 99.5%, adsorbent amount of chlorine is higher, by the mode vacuumizing, the purer chlorine of reentrying.
Main operating parameter
Pressure-variable adsorption adsorptive pressure :～0.3MPa
Product oxygen pressure: 0.25MPa (than the low 0.05MPa of raw gas pressure)
Product chlorine gas pressure: normal pressure
Pressure swing adsorption operations temperature: 60～100 ℃
Pressure-variable adsorption desorption pressures :-0.07MPa
The process design parameter of device
Unstripped gas condition
Form:
Chlorine content: 70%
Oxygen content: 30%
Water content :≤200ppm
Flow: 2500Nm
3/ h
Pressure: 0.3MPa
Reclaim oxygen requirement
Reclaim oxygen content: >=99.5%
Unit capacity adjustable range: 30～110%
Reclaim oxygen pressure: >=0.25MPa
Oxygen temperature: 60 ℃
Oxygen recovery rate: 98.5%
Number during design operation: annual continued operation
Reclaim chlorine requirement
Reclaim chlorine content: >=99.2%
Unit capacity adjustable range: 30～110%
Reclaim chlorine gas pressure: 0.02MPa (normal pressure)
Chlorine temperature: 60 ℃
The chlorine rate of recovery: 99.0%
Number during design operation: annual continued operation
Table 1PSA adsorbent
Below, with reference to accompanying drawing, specifically describe the preferred embodiments of the present invention.The following example is only for further describing the inventive method.Above disclosed the spirit and scope of the present invention be not subject to the restriction of these embodiment.
Embodiment 1
This example is four tower pressure swing adsorption methods of chloration hydro-oxidation mixed gas separation recovery chlorine and oxygen, and unstripped gas composition (removing device and drying device processing through hydrogen chloride) and flow are as shown in table 2.
Table 2 chloration hydro-oxidation gaseous mixture composition after pretreatment and flow
This routine pressure swing adsorption system is comprised of 4 adsorption towers, 1 vavuum pump and corresponding program-controlled valve, pipeline.Wherein 1 adsorption tower is in adsorbed state, and 1 in vacuumizing reproduced state, and all the other two in equal pressure condition, and this routine process using is all pressed for 1 time.Adsorptive pressure is gauge pressure 0.3MPa, and adsorption temp is normal temperature.
Material mixed gas (is essentially chlorine and oxygen) after pretreatment and enters pressure swing adsorption system and carries out separated recovery, chlorine is adsorbed agent and is adsorbed in bed, and oxygen is not adsorbed substantially, directly, through bed, at the adsorption tower port of export, can obtain highly purified oxygen.After adsorption step completes, carry out equal pressure drop, rapid along strideing, for improving product purity of chlorine gas feeding, increase displacement step, displacement gas is chlorine, and the replacement of oxygen of dead space in tower is gone out, and the gaseous mixture displacing returns in unstripped gas to guarantee gas product yield.Finally vacuumize again step and obtain highly purified chlorine.Purity of product gas and yield are as shown in table 3.
Table 3 purity of product gas and yield
Embodiment 2
This example is four tower pressure swing adsorption methods of chloration hydro-oxidation mixed gas separation recovery chlorine and oxygen, and unstripped gas composition (removing device and drying device processing through hydrogen chloride) and flow are as shown in table 4.
Table 4 chloration hydro-oxidation gaseous mixture composition after pretreatment and flow
This routine pressure swing adsorption system is identical with embodiment 1.Wherein 1 adsorption tower is in adsorbed state, and 1 in vacuumizing reproduced state, and all the other two in equal pressure condition, and this routine process using is all pressed for 2 times.Adsorptive pressure is gauge pressure 0.5MPa, and adsorption temp is normal temperature.
This routine pressure-changing process flow is basically identical with example 1 except all pressing number of times.Products obtained therefrom gas purity and yield are as shown in table 5.
Table 5 purity of product gas and yield
Although describe the present invention in detail in above illustrating, should be understood that, described details is only for illustrating, and those skilled in the art can make change to it within not deviating from the spirit and scope that claim of the present invention limits.
Claims (1)
1. a method that adopts chlorine and oxygen in pressure swing adsorption separation and recovery of chlorine hydroxide gaseous mixture, is characterized in that comprising following three steps:
Step 1: material mixed gas is absorbed and removed the complete hydrogen chloride of unreacted by water, gaseous mixture enters from absorption tower T1 bottom side mouth, at T1 top, absorption tower bubble column spray, inject appropriate water simultaneously, in absorption tower T1 bottom packed tower and top bubble column, the hydrogen chloride water in the gaseous mixture of rising is carried out to blended absorbent, T1 bottom in absorption tower connects salt acid circulating pump P1 and returns to packed tower top formation closed circuit, the hydrochloric acid that makes blended absorbent in filler again with the gaseous mixture rising in the hydrogen chloride absorption enrichment that circulate, when reaching, concentration of hydrochloric acid sets after index, beginning is by absorption tower T1 bottom extraction hydrochloric acid, not yet absorbed hydrogen chloride rises in the bubble column of top and all absorbs,
Step 2: gaseous mixture enters concentrated sulfuric acid drying tower and removes the water that catalytic reaction produces; Gaseous mixture enters from concentrated sulfuric acid drying tower T2 bottom side mouth, at inner-tower filling material, soak the full concentrated sulfuric acid simultaneously, moisture content in the gaseous mixture rising carries out blended absorbent with the concentrated sulfuric acid, moisture content in gaseous mixture rises to tower top and is all absorbed, the concentrated sulfuric acid is diluted gradually, when sulfuric acid concentration dilution reaches, set after index, start, by drying tower T2 bottom extraction dilute sulfuric acid, to refill the appropriate concentrated sulfuric acid;
Step 3: after premenstrual two-step method, gaseous mixture is sent to Vacuum Pressure Swing Adsorption VPSA system again and carried out chlorine and oxygen separation; Vacuum Pressure Swing Adsorption VPSA system is comprised of at least two adsorption tower unit, in each adsorption tower, adopt the adsorbent of same way filling equal number, it is more than 99.2% chlorine that unstripped gas obtains purity after adsorbing, all press, replace, vacuumizing desorption procedure, and in absorption tail gas, obtain purity is more than 99.5% oxygen simultaneously; Described adsorbent is silica gel and active carbon, and its type of feed is that active carbon is placed in adsorption tower lower end, and silica gel is placed in adsorption tower upper end; In adsorption process, the adsorptive pressure of each adsorption tower is gauge pressure 0.1～1.0MPa, and adsorption temp is normal temperature; Before vacuum desorption step, increase flushing operation to improve the purity of chlorine gas feeding in stripping gas, purge gas is gas product chlorine; Pressure-variable adsorption adopts 4-1-2 flow process, device is comprised of four adsorption tower T3a～T3d, an equalizer tank V1 and a vavuum pump P2, in four adsorption towers, adsorption tower different phase in absorption wherein, an adsorption tower is in vacuumizing regenerative process, another two adsorption towers are in all pressing and the suitable journey of letting slip, in whole separation process, technical process experienced absorption, twice drop pressure, along putting, replace, vacuumize, twice boost pressure and nine steps of product oxygen pressure rising, the detailed process of each step is as follows:
(i) adsorption process: contain the unstripped gas of chlorine and oxygen after heat exchange, temperature constant directly enters from the bottom of adsorption tower after certain value, wherein chlorine is adsorbed onto on Special adsorbent entirely, and the oxygen not being adsorbed etc. can be smoothly by the adsorbent bed battery limit (BL) of sending;
(ii) drop pressure process: this process is along absorption direction, the gas of adsorption tower is carried out to drop pressure by all pressing with the adsorption tower of another boost pressure, this process is all to another adsorption tower by the component oxygen that is difficult for absorption in adsorption tower, reduce gradually on the one hand the pressure of adsorption tower, meet the condition of adsorption tower desorption and regeneration, reclaim on the other hand the interior a small amount of chlorine of dead space in adsorption tower, it all presses number of times is twice;
(iii) along putting decompression process: complete after pressure equalizing, again along absorption direction, the pressure of adsorption tower is reduced gradually, the chlorine being now adsorbed on adsorbent starts desorb, the chlorine of separating sucking-off is full of whole adsorption tower dead space gradually, makes the purity of chlorine gas feeding that stops and be adsorbed reach required value as far as possible; Along the gas containing part chlorine of emitting, after pressurization, turn back to native system unstripped gas entrance;
(iv) replacement process: along letting slip after journey, along the direction of absorption, with a small amount of chlorine, adsorption tower is replaced again, replacement of oxygen a small amount of in adsorption tower headroom is gone out to adsorption tower, improve chlorine gas concentration in adsorption tower, displacement gas also returns to feed(raw material)inlet compressor, and recovery capable of circulation is chlorine wherein;
(v) vacuum desorption process: after completing and forward bleeding off pressure and replace, gas component in adsorption tower is mainly chlorine, concentration is more than 99%, now adopt the mode vacuumizing, make the chlorine of absorption in adsorption tower be able to desorb under vacuum state, separate the product chlorine that the gas of sucking-off is recovery, after surge tank buffering, send battery limit (BL);
(vi) boost pressure process: boost pressure is corresponding with drop pressure, the pressure of the adsorption tower that raises gradually on the one hand, prepares for absorption next time, reclaims on the other hand a small amount of chlorine in another adsorption tower step-down process, and all pressing number of times is twice;
(vii) the product oxygen process of finally boosting: complete in vacuum regeneration process, and after all pressing, for adsorption tower is switched in the process of adsorbing reposefully next time, there is not pressure oscillation, need to adsorption column pressure be risen to adsorptive pressure with the oxygen of separating; This process not only makes adsorption tower boost, for absorption next time is prepared, simultaneously also with respect to the process to a flushing at adsorption tower outlet position, a small amount of chlorine of absorption in the adsorbent of adsorption tower exit position is moved to adsorption tower arrival end, and while guaranteeing next time adsorbing separation, oxygen purity arrives requirement.
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| CN103832975B (en) * | 2014-01-24 | 2015-10-28 | 上海方纶新材料科技有限公司 | The method of chlorine and oxygen is reclaimed from the gas mixture of chloride and oxygen |
| CN104592000B (en) * | 2014-12-22 | 2017-01-11 | 上海方纶新材料科技有限公司 | Cleaning process of preparing chloroformyl substituted benzene |
| CN106076074B (en) * | 2016-08-03 | 2018-08-28 | 安徽八一化工股份有限公司 | Two sections of exhaust gas processing devices in a kind of benzene chloride production |
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| CN109603421A (en) * | 2018-11-06 | 2019-04-12 | 杨皓 | A kind of activation method of dechlorination pressure-variable adsorption carbon molecular sieve |
| CN110240963B (en) * | 2019-06-24 | 2021-04-16 | 浙江天采云集科技股份有限公司 | Coupling purification method for raw material gas and reaction circulating gas in methane method for preparing chloromethane |
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| CN112744787B (en) * | 2020-12-16 | 2022-05-03 | 四川天采科技有限责任公司 | FTrPSA separation and purification method for deeply defluorinating and drying HCl gas containing high-concentration HF |
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| CN113398719A (en) * | 2021-06-15 | 2021-09-17 | 山东东岳氟硅材料有限公司 | Device and method for recovering chlorine in tail chlorine |
| CN113304582B (en) * | 2021-07-29 | 2022-01-14 | 北京汇安苍生科技有限公司 | Method and device for concentrating ozone by pressure swing adsorption |
| CN115806273A (en) * | 2022-09-30 | 2023-03-17 | 西北民族大学 | Product separation process and device for preparing chlorine gas by catalytic oxidation of hydrogen chloride |
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| EP0518553A1 (en) * | 1991-06-06 | 1992-12-16 | MITSUI TOATSU CHEMICALS, Inc. | Method and apparatus for industrially preparing chlorine |
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