CN101213009B - Process for producing a gas stream depleted of mercaptans - Google Patents
Process for producing a gas stream depleted of mercaptans Download PDFInfo
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- CN101213009B CN101213009B CN2006800237326A CN200680023732A CN101213009B CN 101213009 B CN101213009 B CN 101213009B CN 2006800237326 A CN2006800237326 A CN 2006800237326A CN 200680023732 A CN200680023732 A CN 200680023732A CN 101213009 B CN101213009 B CN 101213009B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1487—Removing organic compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1493—Selection of liquid materials for use as absorbents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
- B01D2253/10—Inorganic adsorbents
- B01D2253/106—Silica or silicates
- B01D2253/108—Zeolites
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
- B01D2253/30—Physical properties of adsorbents
- B01D2253/302—Dimensions
- B01D2253/308—Pore size
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/30—Sulfur compounds
- B01D2257/306—Organic sulfur compounds, e.g. mercaptans
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/702—Hydrocarbons
- B01D2257/7027—Aromatic hydrocarbons
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Abstract
The invention provides a process for producing a gas stream depleted of RSH from a feed gas stream comprising natural gas, RSH and aromatic compounds based on the whole feed gas stream of 1 ppmv to 1 vol% selected from the group of benzene, toluene, o-xylene, m-xylene and p-xylene, the process comprising the steps of: (a) contacting the feed gas stream with absorbing liquid comprising a physical solvent in an aromatic compound removal zone to obtain loaded absorbing liquid comprising aromatic compounds selected from the group of benzene, toluene, o-xylene, m-xylene and p-xylene and a gas stream depleted of these aromatic compounds; (b) contactingthe gas stream obtained in step (a) with solid adsorbent in a mercaptan removal zone to obtain solid adsorbent loaded with RSH and the gas stream depleted of RSH.
Description
Technical field
The present invention relates to from comprising the method that RSH and the natural gas stream of the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene are produced the gas stream of depleted of mercaptans (RSH).
Background technology
Produce the gas stream of the poor RSH of containing and comprise and remove RSH from comprising RSH and the natural gas stream of the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene.Consider to continue strict environmental specification that it is quite important always in the past and at present even especially like this to remove RSH from the gas stream that comprises these compounds.
Many natural gas wells produce " acid gas ", promptly usually be selected from the aromatic compounds of benzene, toluene, ortho-xylene, meta-xylene and paraxylene and other sulfur-containing compound such as H
2S, sulfide, disulphide and thiophene comprise the natural gas of RSH together.The total amount of compound is too high usually, makes natural gas be inappropriate for direct use.In addition, natural gas can further comprise the carbon dioxide of variable quantity.Plan purposes according to natural gas also must remove carbon dioxide usually.
Usually, need be less than the sulfur-containing compound total concentration of 30ppmv.The acid gas standard is mentioned less than 10ppmv usually or even is low to moderate the total sulphur concentration less than 4ppmv.
Wherein removing the very important a kind of situation of RSH from natural gas stream is that wherein gas stream is intended for use the situation of domestic use.Mercaptan is owing to their odor property can detect under a few millionths part concentration level.Therefore, RSH concentration is dropped to as less than 10 or even less than 5ppmv.
Wherein to remove important another kind of situation be to be intended for use to relate to the situation in the method for catalytic step at natural gas stream to mercaptan.For example, natural gas can be used for typically in gasifier unit, producing forming gas.Be converted into hydrocarbon known in the art for the forming gas that will form so usually in the catalysis process of Fischer-Tropsch process.If RSH exists in natural gas stream, they can reaction form H in gasifier
2S obtains comprising H
2The forming gas logistics of S.The H that forms like this
2S possibly irreversibly combine and cause sulfur poisoning on catalyst.This causes seriously hindering the catalyst of the inactivation of catalytic process.Therefore method comprises under the situation of catalytic step therein, requires RSH is removed to low-down level, is low to moderate less than 2ppmv or even in the scope of ppbv.
The method that removes RSH from the gas stream that comprises natural gas and RSH is known in the art and usually based on solid bed adsorption or physics and/or chemical absorbing.
Physical absorption process is subject to the following fact: they often are difficult to RSH is removed to low concentration.Usually, need big contactor to reach required low concentration.
Chemical absorption process can remove carbon dioxide and/or hydrogen sulfide and not big difficulty usually.But they are subject to the following fact: they can not remove RSH effectively and produce a large amount of refuses usually.For example, in EP 229,587, describe a kind of method, wherein adopted alkaline aqueous liquid handling gas stream.In the method described in the EP 229,587, need the lot of consumption alkaline chemical to remove RSH.
The solid bed adsorption method is suitable for the absorption of RSH usually.But they can be subject to the following fact: also possibly adsorb the compound beyond the RSH, the use that causes only adsorbing limited amount RSH or cause very big adsorbent bed.The gas stream of producing the poor RSH of containing from the gas stream that comprises other compound is difficult, especially when needing low RSH level.The regeneration of adsorbent bothers relatively.Particularly big adsorbent bed needs the more relatively recovery time and disproportionately needs a large amount of regeneration gas.
Therefore, this area need remove the simple and efficient method of RSH with the gas stream that is selected from the aromatic compounds of benzene, toluene, ortho-xylene, meta-xylene and paraxylene from comprising RSH, so obtains to have the purified gas stream of low RSH concentration.
Summary of the invention
For this purpose; The present invention provides from the method that comprises natural gas, RSH and produce the gas stream of the poor RSH of containing based on the feed gas stream of the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene of total raw material gas stream meter 1ppmv to 1vol%, and said method comprises the steps:
(a) said feed gas stream is contacted with the absorption liquid that comprises physical solvent, comprise the absorption liquid and the poor gas stream that contains these aromatic compounds of the load of the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene with acquisition;
(b) remove at mercaptan the gas stream that obtains in the step (a) is contacted with solid absorbent, with solid absorbent and the poor gas stream that contains RSH of acquisition load RSH.
The specific embodiment
Have been found that the absorption of the aromatic compounds interference RSH that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene (being referred to as the BTX compound), especially when using zeolite as adsorbent.It is believed that the preferential adsorption that these aromatic compounds take place, especially when the use zeolite for as adsorbent the time.Therefore, the feed gas stream that will comprise RSH and BTX compound is regarded as using absorbing process to produce the difficult feed gas stream of the gas stream of the poor RSH of containing from it, especially when using zeolite as adsorbent.The simple and efficient mode that method of the present invention provides even produces the gas stream of the poor RSH of containing from this feed gas stream, this is owing to before making gas stream experience adsorption process, the BTX compound is removed to bigger degree.This causes the obviously better absorption of RSH to the zeolite adsorbents, produces the low poor gas stream that contains RSH of RSH concentration.
The further advantage of the inventive method is that it can confirm as required that aromatics removes the district and mercaptan removes the size in district.This can realize the general mode of operating procedure.In addition, through designing two zones as requested, also can reach process optimization.
In the step (a) of the inventive method; With the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene from comprise natural gas, be selected from benzene, the feed gas stream of the aromatic compounds of toluene, ortho-xylene, meta-xylene and paraxylene and RSH transfers to and absorbs the liquid, obtains to comprise absorption liquid and the gas stream of the poor BTX of containing compound of the load of BTX compound.
Natural gas is the generic term that is used for from the natural gas well light hydrocarbon that obtains and the mixture of choosing other gas (nitrogen, carbon dioxide, helium) wantonly.The key component of natural gas is a methane.Usually there are ethane, propane and butane in addition.Can exist (lacking) amount to be typically expressed as the more higher hydrocarbon of natural gas liquids or condensate in some cases.When producing with oil, natural gas is commonly referred to associated gas.Possibly comprise H with other compound that variable quantity exists in natural gas
2S, aliphatic RSH, sulfide, disulphide, thiophene and aromatics RSH.
Refer at this RSH that mentions: aliphatic mercaptan, particularly C
1-C
6Mercaptan is more especially C
1-C
4Mercaptan; Aromatic mercaptans, particularly phenyl mercaptan; Or the mixture of aliphatic series and aromatics RSH.The present invention be more particularly directed to remove methyl mercaptan, ethanethio, n-pro-pyl and isopropyl mercaptan and butyl mercaptan isomers from feed gas stream.Be called C below containing the mercaptan of 3 or more carbon atoms
3+ RSH.
The concentration of the RSH that exists in the feed gas stream and the type of RSH maybe be different and depend on the source of first gas stream.Suitably, the total raw material gas stream comprises the RSH of 1ppmv to 1vol% and the BTX compound of 1ppmv to 1vol%, and the RSH of preferred 20ppmv to 1vol% and the BTX compound of 5ppmv to 1vol% are based on total raw material gas stream meter.To comprise the RSH of these concentration ranges and the feed gas stream of BTX compound is regarded as using adsorbent technology to produce the very difficult feed gas stream of the gas stream of the poor RSH of containing from it.
Randomly, feed gas stream can further comprise H
2S, preferred 1ppmv to 10vol%, the more preferably H of 0.1-10vol%
2S is based on total raw material gas stream meter.Have been found that H
2The existence of S hinders removing of RSH in the conventional absorbing process, and particularly when using zeolite as adsorbent, this is because H
2S preferentially adsorbs on zeolite.Therefore, incite somebody to action wherein H
2S concentration is 0.1-10vol%H
2S comprises RSH, BTX compound and H
2The gas stream of S is regarded as producing the very difficult feed gas stream of the gas stream of the poor RSH of containing.Method of the present invention can even be produced the poor gas stream that contains RSH from this feed gas stream, this be because in step (a) with H
2S is removed to big degree from feed gas stream, obtains the poor BTX of containing compound and the poor H of containing
2The gas stream of S.
Feed gas stream also can comprise carbon dioxide, preferred 0-40vol%, and the more preferably carbon dioxide of 0-30vol% is based on total raw material gas stream meter.Usually need to reduce concentration of carbon dioxide, particularly feed gas stream comprises natural gas and is processed under the situation of liquefied natural gas (LNG) with the gas stream of planning the poor RSH of containing therein.Method of the present invention can be produced the poor carbonated gas stream with low concentration of carbon dioxide, and this is owing in step (a), carbon dioxide is removed to big degree from feed gas stream.
Absorbing liquid comprises and can remove BTX compound and optional C from feed gas stream
3The physical solvent of+RSH.Preferably, the amount of physical solvent is 10-80, more preferably 15-50, more preferably 20-35 weight portion still, based on total absorption level meter.The remainder that absorbs liquid is another kind of solvent, preferred water and/or amine solvent suitably.
Preferred physical solvent is selected from sulfolane (ring tetramethylene sulfone and derivative thereof), aliphatic acid amides, N-methyl pyrrolidone, N-alkylated pyrrolidones and corresponding mixture of sending pyridine ketone, methyl alcohol, ethanol and polyethylene glycol dialkyl ether.Most preferred physical solvent is a sulfolane.
The advantage that use comprises the absorption liquid of physical solvent is that the BTX compound is removed to is low-level, even the ppmv scope.The BTX compound is a carcinogenic substance and therefore their discharging must be lower than certain level.Therefore must reduce BTX compound concentrations in the gas stream.More importantly, have been found that the existence obstruction RSH of BTX compound is adsorbed onto on the adsorbent, especially be adsorbed onto on some type zeolite.Therefore, pretty troublesome through the gas stream that conventional absorbing process is produced the poor RSH of containing from the feed gas stream that comprises RSH and BTX compound, particularly when the use zeolite adsorbents.Can not reach RSH in the gas stream of the poor RSH of containing low-level (typically being the ppmv scope) through the technology of using zeolite adsorbents.
Another advantage that use comprises the absorption liquid of physical solvent is to make according to thinking to be difficult to the RSH (C that contains three carbon atoms or more carbon atoms that removes through conventional absorbing process
3+ RSH) also in physical solvent, absorb and therefore remove from feed gas stream.
Preferably, absorbing liquid is the mixed solvent that comprises physical solvent and chemical solvent.The absorption liquid that preferably comprises chemical solvent and physical solvent, this is because with respect to the good absorbability of their demonstrations of suitable cost of investment and running cost with for H
2The good selectivity of S.In addition, comprise in feed gas stream under the situation of carbon dioxide, also can in blended absorbent liquid, remove carbon dioxide, obtain the poor H of containing according to solvent composition
2S and poor carbonated gas stream.Another advantage of mixed system is that they show under high pressure better, and performance is better under the pressure of 20-90bara especially.Therefore under situation,, then do not need depressurization steps if for example feed gas stream is the natural gas stream that under high pressure obtains with the feed gas stream pressurization.Another advantage is to use the proven physical/chemical absorption liquid of mixing rather than only uses Physical Absorption liquid also to obtain the possibility of any carbon dioxide of flash distillation under relatively high pressure power (being 5-15bara).This has reduced as being used for reflooded recompression requirement.
Suitable chemical solvent is primary amine, secondary amine and/or tertiary amine, especially derived from amine, particularly MEA (MEA), diethanol amine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA) (DIPA) and methyl diethanolamine (MDEA) or its mixture of monoethanolamine.Preferred chemical solvent is secondary amine or tertiary amine, preferably derived from the amines of monoethanolamine, is more especially DIPA, DEA, MMEA (monomethyl-monoethanolamine), MDEA or DEMEA (diethyl-MEA), the amines of preferred DIPA or MDEA.
Absorb liquid and also can further comprise the so-called activator compound that randomly combines with chemical solvent.It is believed that in absorbing liquid system, adding activator compound improves removing of acid compound.This is used in particular for feed gas stream and further comprises H
2The situation of S and/or carbon dioxide.Suitable activator compound is piperazine, methylethanolamine or (2-amino-ethyl) monoethanolamine, particularly piperazine.
The preferred liquid system that absorbs comprises sulfolane and secondary amine or tertiary amine, preferably derived from the amines of monoethanolamine, is more especially DIPA, DEA, MMEA (monomethyl-monoethanolamine), MDEA or DEMEA (diethyl-MEA), preferred DIPA or MDEA.In the aqueous absorbent of this method, the amount of water is preferably the 20-45 weight portion, and the amount that the amount of sulfolane is preferably 20-35 weight portion and amine is preferably the 40-55 weight portion, and the amount of water, sulfolane and amine is 100 weight portions together.Preferred range in most of the cases obtains optimum carbon dioxide eliminating.
Another kind of preferred water that liquid comprises 15-45 weight portion (preferred 15-40 weight portion), 15-40 weight portion sulfolane, the 30-60 weight portion of absorbing is derived from the secondary amine of monoethanolamine or the activator compound (preferred piperazine) of tertiary amine and 0-15wt% (preferred 0.5-10wt%), and all weight portions are 100 weight portions based on water, sulfolane, amine and the activator amount together of total solution and adding.This preferred absorption liquid body can remove these compounds from the gas stream that comprises carbon dioxide, hydrogen sulfide and/or COS.
This provides advantage with respect to other method that can not remove carbon dioxide.When with do not add primary amine or secondary amine compound, particularly with the same absorbent liquid phase ratio of secondary amine compound; Obtain one or more following advantages: absorption rate of carbon dioxide is faster; Load capacity is higher; The solvent/gas ratio is lower, and Design of device is littler to require lower (obtaining littler cooling capacity) with reactivation heat.When comparing with the absorption liquid that comprises aqueous amine, particularly DMEA and piperazine, the adding of sulfolane can produce have middle pressure such as 3-15bara, the gas stream that comprises carbon dioxide of the pressure of preferred 5-10bara.
Advantage of the present invention is through in step (a), selecting specific absorption liquid, can regulate technology with can be from further comprising other compound, particularly H
2The feed gas stream of S and/or carbon dioxide is produced the poor gas stream that contains RSH.This method also can be produced the gas stream of the poor RSH of containing from the feed gas stream of BTX compound with variable concentrations and/or other compound (like hydrogen sulfide or carbon dioxide).Can select whether to remove for example carbon dioxide and remove these compounds to what degree of some compound.Therefore, can reach the gas streams that in step (a), obtain different compositions.
Suitably, step (a) is carried out under 15-90 ℃ temperature, preferably at least 20 ℃, more preferably 25-80 ℃, still more preferably carry out and even still more preferably under about 55 ℃, carry out under 40-65 ℃ the temperature.Step (a) is suitably at 10-150 crust, carry out under the pressure of 25-90bara especially.
Step (a) is carried out in the zone of containing 5-80 contact layer such as valve plate, bubble cap plate, baffle plate etc. suitably.Also can use structured packing.Can be through regulating solvent/feed gas ratio optimization CO
2-the degree that removes.Suitable solvent/feed gas ratio is 1.0-10 (w/w), preferred 2-6.
Because the BTX compound is transferred to absorption liquid from feed gas stream, make the poor BTX of the containing compound of gas stream and optional C that obtain in the step (a)
3+ RSH this means BTX compound and optional C in the gas stream that obtains in the step (a)
3The concentration of+RSH is lower than these compound concentrations in the feed gas stream.Should understand BTX compound and optional C in the gas stream that obtains in the step (a)
3The concentration of+RSH depends on these compound concentrations in the feed gas stream.Suitably, the total concentration of BTX compound is preferably 1-100ppmv, more preferably 1-50ppmv less than 500ppmv in the gas stream that obtains in the step (a).Suitably, C in the gas stream that obtains in the step (a)
3The concentration of+RSH is less than 10ppmv, preferably less than 5ppmv.
The concentrations of mercaptans that should understand in the gas stream that step (a) obtains afterwards depends on the concentrations of mercaptans in the feed gas stream.Suitably, the concentrations of mercaptans in the gas stream that step (a) obtains afterwards is 100ppbv to 5vol%.
In step (a), obtain to comprise BTX compound and optional other compound (like C
3+ RSH, hydrogen sulfide and optional carbon dioxide) and the absorption liquid of the load of other sulphur compound (like carbonyl sulfide).Step (a) is carried out as continuation method usually, and this method also comprises the regeneration of the absorption liquid of load.Therefore; Aromatics removal zone comprises at least one regenerator in preferred embodiments, in this regenerator typically under low relatively pressure and high temperature through making at least a portion compound transfer to the regenerate absorption liquid of load of regeneration gas stream.Suitably, regeneration temperature is 70-150 ℃.Preferably through adopting the heating of steam or deep fat to reach required temperature.Preferably, progressively increase temperature.Suitably, regeneration is carried out under the pressure of 1-2bara.The absorption liquid of load comprises the BTX compound and can further comprise C
3+ RSH and optional CO
2, H
2S and/or COS.Other compound such as hydrocarbon condensate from the obvious amount of feed gas stream also possibly exist in the absorption liquid of load.Can be advantageously through being flashed to the pressure that is higher than the dividing potential drop summation that belongs to this compound and these compounds are removed at least in part from the solvent of load.Usually flash distillation is at the pressure of 1-15bara, preferred 1-10bara, more preferably carry out under the environmental pressure.Preferably under atmospheric pressure carry out flash distillation.Temperature in the flash distillation operation is 50-120 ℃ suitably, preferred 60-90 ℃.
Absorption liquid that regeneration technology obtains regenerating and the C that comprises the BTX compound and choose wantonly
3The regeneration gas stream of the load of+RSH, hydrogen sulfide, carbon dioxide and/or carbonyl sulfide.Suitably, in sulfur recovery unit, for example remove sulphur compound from the regeneration gas stream of load through the Claus method.Suitably, the liquid-absorbant of at least a portion regeneration is used to remove above-mentioned BTX compound.
Preferably, the poor absorbent solvent of at least a portion is used for the absorption stage of step (a) once more.Suitably, with the solvent heat exchange of lean solvent and load to use said heat elsewhere.
In step (b), the gas stream of the poor BTX of the containing compound that obtains in the step (a) is contacted with solid absorbent.Therefore remaining RSH is transferred to solid absorbent from gas stream.
Suitable solid adsorbent materials comprises the material based on silica, silica gel, aluminium oxide or silica-alumina.
Preferably, zeolite is used for mercaptan-adsorbent bed.Zeolite is the solid absorbent that contains the perforate that can let material get into or pass through.In the zeolite of some types, perforate be defined as bore dia suitably and in other type perforate be defined as the perforate in the basket structure suitably.Preferred average perforate (bore dia) be 5
or bigger zeolite, more preferably average perforate (bore dia) is the zeolite of 6-8
.Preferred average especially perforate (basket structure) be about 7.4
the 13X zeolite.It is believed that average perforate be 5
or bigger zeolite allows the absorption of methyl mercaptan, ethanethio and n-pro-pyl mercaptan and therefore they are removed from gas stream.It is believed that average perforate is that zeolite, particularly the 13X zeolite of 6-8
also allows to adsorb for example isopropyl mercaptan of branching RSH.Therefore; Zeolite, particularly 13X zeolite facies that average perforate is 6-8
provide advantage for the zeolite of littler average diameter, and this is because they allow to remove all RSH (comprising branching RSH).But, have been found that the BTX compound also is adsorbed onto on the zeolite that average perforate is 6-8
, has particularly hindered the absorption of RSH on the 13X zeolite and owing to their preferential adsorption.Therefore can not use and comprise that average perforate is 6-8
The solid absorbent of zeolite, particularly 13X zeolite produce the poor RSH of containing from the feed gas stream that comprises the BTX compound and (comprise C
3+ RSH) gas stream.But; Owing to remove before the BTX compound in that gas stream is contacted with solid absorbent, method of the present invention can use average perforate as zeolite, particularly the 13X zeolite of 6-8
as solid absorbent.Although with at least a portion C
3+ RSH removes in step (a), still has number of C in the gas stream that typically in step (a), obtains
3+ RSH.In step (b), use average perforate to be 6-8
Zeolite, particularly 13X zeolite can remove remaining C as solid absorbent
3+ RSH, with at the poor RSH that contains, gas stream in reach low-down RSH total concentration level.Therefore can reach the level that is low to moderate less than 1ppmv.
In hydrocarbon stream, exist under the situation of water; When preferably through in perforate be 5
or littler, be preferably 3 or 4
zeolite molecular sieve on adsorbed water and removing when removing water in the unit at water before the removing of RSH, obtain more efficient methods.In this zeolite, adsorb any RSH hardly, main adsorbed water.Usually, the ability of this zeolite is higher than the more zeolite of macropore.The water yield that removes maybe be little or big, but preferably remove the water of 60wt%, preferred 90wt% at least.Very suitably in leaving water removes the gas stream of unit, water is removed to the level less than 1%v, preferably is removed to level, more preferably be removed to level less than 5ppmv less than 100ppmv.
The operating temperature that mercaptan removes solid adsorbent beds in the district can change in wide region and be 0-80 ℃ suitably, and preferred 10-60 ℃, pressure is 10-150bara suitably.Empty tower gas velocity is 0.03-0.6m/s suitably, preferred 0.05-0.40m/s.
Preferred especially adsorbent is the adsorbent that comprises the 13X zeolite.Using the advantage of 13X zeolite is can adsorb to comprise C
3All RSH of+RSH.Although make at least a portion C
3+ RSH removes in step (a), but according to C in condition in the step (a) and the feed gas stream
3The gas stream that obtains in the concentration of+RSH, step (a) typically still comprises number of C
3+ RSH.This provides and removes RSH to low-level possibility, obtains having the gas stream less than the poor RSH of containing of 1ppmv RSH concentration suitably.
Typically, the process in the mercaptan absorbing unit obtains not containing basically the purified gas stream of RSH and mercaptan-adsorbent bed of present load RSH.Should understand method of the present invention and preferably carry out with continuous mode, this will comprise the regeneration of load adsorbent bed.
Can contact with gas stream through the bed that under high temperature or decompression, makes the mercaptan load and recover the absorption of RSH on the mercaptan adsorbent.Therefore, RSH is transferred to regeneration gas stream from mercaptan-adsorbent bed, obtain the gas stream of load RSH, this gas stream is first gas stream of the present invention.Suitable gas logistics to this purpose for example is inert gas stream or appropriate hydrocarbon gas logistics.For the object of the invention, a part of purifying hydrocarbon stream that preferably use hydrocarbon stream, particularly leaves mercaptan-absorbing unit is as regeneration gas stream.
Preferably, use two or more adsorbent beds that comprise solid absorbent (preferred zeolite).Typically, at least one adsorbent bed adopts absorption mode and at least one adsorbent bed to adopt desorption mode.Depend on actual state can exist two, three, four or even the combination of more adsorbent beds, an adsorbent bed is in absorption mode, other adsorbent bed is in the different phase of desorption mode.
Gas stream at this depleted of mercaptans of mentioning refers to wherein with H
2The two concentration of S and RSH all is reduced to the gas stream of acceptable level for the plan purposes of gas stream.
Can with the gas stream of depleted of mercaptans for example adopt in a known manner through catalysis or noncatalytic combustion further processing or as the unstrpped gas of chemical reaction, or be used to produce liquefied natural gas (LNG), or be used for domestic use producing electricity, heat or power.The present invention also provides the LNG that obtains from the gas stream of the poor RSH of containing that liquefies.The LNG that obtains so typically has the compound concentration beyond the low-down natural gas.The advantage of method of the present invention is that the gas stream of the poor RSH of containing comprises very low-level impurity, particularly sulphur impurity, makes it possible to produce LNG and the other step that need not remove sulphur impurity.
In the method for the invention, adopt effective and efficient manner production to have the gas stream of very low RSH concentration (suitably in the ppmv scope).Because in step (a), only removing a part of RSH (is C
3+ RSH), so this method avoids the use of very big and inefficient reactor.Relatively little solid adsorbent bed can be used to remove the RSH of remainder in step (b).This is due to the following facts: and in step (a), removed nearly all hydrogen sulfide with part RSH.The regeneration of this bed is not to require great effort very much or bother.Therefore, even the combination of the step of the inventive method obtains in the presence of hydrogen sulfide and carbon dioxide avoiding simultaneously from the gas stream that the feed gas stream that comprises RSH and BTX compound is produced the poor RSH of containing the overall effective ways of only a kind of technology or other technological shortcoming.In addition, technology has been optimized in the processing of the regeneration gas of solid bed adsorption device in the dedicated suction adnexa.Then the loaded solvent of dedicated suction adnexa is being regenerated with the same regeneration device that is used for main process.
The present invention is now through following non-limiting example explanation.
Embodiment 1 (contrast)
Under the pressure of 45 ℃ temperature and 60barg, contact in adsorber unit forming feed gas stream and the absorption liquid that comprises MDEA and piperazine shown in the A row of table 1.The composition that leaves the gas stream of adsorber unit is seen the B row of table 1.The gas stream that leaves adsorber unit is contacted with the big adsorbent bed that comprises the 13X zeolite.Use the gas stream that leaves adsorbent bed of gas chromatographic measurement still to comprise the RSH of concentration greater than 10ppmv.
Embodiment 2 (the present invention)
Feed gas stream and the absorption liquid that comprises physical solvent formed shown in the A row of table 1 are contacted under the pressure of 45 ℃ temperature and 60barg.The composition that leaves the gas stream of adsorber unit is seen the C row of table 1.The gas stream that leaves adsorber unit is contacted with the little adsorbent bed that comprises the 13X zeolite.RSH concentration is less than 2ppmv in the gas stream that leaves adsorbent bed of use gas chromatographic measurement.
Table 1: in the concentration of component of mol%.All BTX compounds and all RSH in ppmv.
| ? | A | B | C |
| H 2O | 0.010 | 0.201 | 0.223 |
| CO 2 | 2.118 | 0.000 | 0.002 |
| H 2S | 0.432 | 0.000 | 0.000 |
| CH 3SH | 0.004 | 0.003 | 0.000 |
| C 2H 5SH | 0.011 | 0.001 | 0.001 |
| i-C 3H 7SH | 0.001 | 0.001 | 0.000 |
| N 2 | 3.715 | 3.811 | 3.831 |
| C 1 | 84.622 | 86.715 | 86.814 |
| C 2 | 5.387 | 5.529 | 5.499 |
| C 3 | 1.777 | 1.823 | 1.798 |
| iC 4 | 0.619 | 0.634 | 0.622 |
| nC 4 | 0.654 | 0.670 | 0.652 |
| iC 5 | 0.184 | 0.189 | 0.182 |
| nC 5 | 0.159 | 0.163 | 0.156 |
| C 6 | 0.135 | 0.138 | 0.129 |
| C 7 | 0.058 | 0.058 | 0.053 |
| C 8 | 0.019 | 0.019 | 0.017 |
| Benzene | 0.042 | 0.029 | 0.011 |
| Toluene | 0.019 | 0.015 | 0.005 |
| All BTX (ppmv) | 610 | 439 | 151 |
| All RSH (ppmv) | 165 | 73 | 12 |
Be apparent that from embodiment method of the present invention can produce the gas stream of RSH concentration less than the poor RSH of containing of 2ppmv.Control methods obtains the gas stream of RSH concentration greater than 10ppmv.
Claims (9)
1. the method from comprising natural gas, RSH and producing the gas stream of the poor RSH of containing based on the feed gas stream of the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene of total raw material gas stream meter 1ppmv to 1vol%, said method comprises the steps:
(a) said feed gas stream is contacted with the absorption liquid that comprises physical solvent, comprise the absorption liquid and the poor gas stream that contains these aromatic compounds of the load of the aromatic compounds that is selected from benzene, toluene, ortho-xylene, meta-xylene and paraxylene with acquisition;
(b) remove at mercaptan the gas stream that obtains in the step (a) is contacted with solid absorbent, with solid absorbent and the poor gas stream that contains RSH of acquisition load RSH.
2. the process of claim 1 wherein that said solid absorbent comprises zeolite.
3. the method for claim 2, wherein said zeolite has the average perforate of
.
4. each method of claim 1-3, wherein said absorption liquid further comprises one or more solvents that are selected from MEA (MEA), diethanol amine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA) (DIPA) and methyl diethanolamine (MDEA).
5. each method of claim 1-3, wherein said physical solvent comprises one or more compounds that are selected from sulfolane, aliphatic acid amides, N-methyl pyrrolidone, N-alkylated pyrrolidones, methyl alcohol, ethanol and polyethylene glycol dialkyl ether.
6. each method of claim 1-3, wherein said absorption liquid further comprises water.
7. each method of claim 1-3, wherein said absorption liquid comprises sulfolane, secondary amine or tertiary amine and optional water.
8. the method for claim 7, wherein said secondary amine or tertiary amine are DIPA, DEA, MMEA (monomethyl-monoethanolamine), MDEA or DEMEA (diethyl-MEA).
9. each method of claim 1-3, the concentration of RSH is 1ppmv to 1vol% in the wherein said feed gas stream, based on total raw material gas stream meter.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| EP05254198.4 | 2005-07-04 | ||
| EP05254198 | 2005-07-04 | ||
| PCT/EP2006/063786 WO2007003618A1 (en) | 2005-07-04 | 2006-07-03 | Process for producing a gas stream depleted of mercaptans |
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| US8282707B2 (en) | 2010-06-30 | 2012-10-09 | Uop Llc | Natural gas purification system |
| SG188447A1 (en) | 2010-09-09 | 2013-04-30 | Exxonmobil Res & Eng Co | ALKANOLAMINE CO<sb>2</sb> SCRUBBING PROCESS |
| WO2013138422A1 (en) * | 2012-03-16 | 2013-09-19 | Saudi Arabian Oil Company | Recovery method and system for delivering extracted btx from gas streams |
| DE102014118345A1 (en) * | 2014-12-10 | 2016-06-16 | L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude | Process and installation for the purification of raw synthesis gas |
| WO2016150827A1 (en) | 2015-03-20 | 2016-09-29 | Shell Internationale Research Maatschappij B.V. | Process for producing a purified gas stream from natural gas wells |
| US20190299153A1 (en) * | 2018-03-28 | 2019-10-03 | Uop Llc | Layered adsorbent bed for removal of carbon dioxide and heavy hydrocarbons |
| US20210253499A1 (en) | 2018-07-18 | 2021-08-19 | Shell Oil Company | Process and system to purify gas |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4957715A (en) * | 1988-04-15 | 1990-09-18 | Uop | Gas treatment process |
| WO2004047955A1 (en) * | 2002-11-28 | 2004-06-10 | Shell Internationale Research Maatschappij B.V. | Process for removing sulphur compounds including hydrogen sulphide and mercaptans from gas streams |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4957715A (en) * | 1988-04-15 | 1990-09-18 | Uop | Gas treatment process |
| WO2004047955A1 (en) * | 2002-11-28 | 2004-06-10 | Shell Internationale Research Maatschappij B.V. | Process for removing sulphur compounds including hydrogen sulphide and mercaptans from gas streams |
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| EA014385B1 (en) | 2010-10-29 |
| CA2614169A1 (en) | 2007-01-11 |
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| WO2007003618A1 (en) | 2007-01-11 |
| CA2614169C (en) | 2014-01-28 |
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