Background technology
Hydrotreatment can comprise: the hydrotreatment of the hydrofining, hydrocracking, hydrodewaxing etc. of petroleum fractions, also the hydrotreatment of coal tar or coal, the oil fixed bed/suspension bed/ebullated bed of refining or DCL/Direct coal liquefaction etc. altogether can be comprised, i.e. the catalytic hydrogenation reaction of a series of consumption hydrogen such as sensu lato hydrogenating desulfurization, deoxidation, denitrogenation, aromatic saturation, hydrocracking.
The reactive system general flow of hydrotreatment is that raw material mixes with circulating hydrogen, enters the reactor that catalyzer is housed, hydrogenation reaction occurs after heat exchange and heating, and reaction after product, through being separated, can obtain object product as clear gusoline or industrial chemicals etc.Need in the reactive system circulating hydrogen of hydrotreatment to maintain certain concentration of hydrogen sulfide, to keep high reactivity and the selectivity of the catalyzer promoting hydrogenation reaction.
In the raw material of hydrotreatment, sulphur content is too low, or nitrogen content is too high, and in recycle hydrogen system, concentration of hydrogen sulfide can be very low, and this system needs to mend sulphur.
Traditional benefit sulphur method, be to reaction feed pump intake or to appropriate location, reactive system process furnace gangway, inject vulcanizing agent DMDS (Methyl disulfide), after DMDS injects reactive system, namely produce hydrogen sulfide with hydrogen reaction under reaction conditions, reaction formula is as follows:
CH
3-S-S-CH
3+3H
2=2CH
4+2H
2S
Ye You enterprise, for reducing costs, adopts and injects dithiocarbonic anhydride CS
2, the method is the same with DMDS principle.
Raw material is after hydrotreatment, and the nitrogen in raw material and sulphur can hydrocracking be ammonia and hydrogen sulfide, can crystallize into salt blocking water cooler in follow-up process of cooling.Generally to be everlasting water filling before water cooler to dissolve this salt.For processing this part sour water of hydrogenation unit, setting up and putting Sulfur-containing Sewage Stripping Tower to isolate ammonia and hydrogen sulfide.Sour water stripping, namely under bottom reboiler heating condition, tower top goes out hydrogen sulfide.Stripping tower can adopt total reflux form, or tower top fills into the form of purifying waste water at the bottom of tower, with purification tower top gas hydrogen sulfide.
The reaction product of hydrotreatment, often containing hydrogen sulfide, makes final product needed desulfurization.General method is to the low point of desulfurization reacted, fuel gas desulfurization and desulfuration of liquefied gas, desulfurization adopts MDEA (nitrogen methyldiethanolamine) solution, the MDEA solution having absorbed hydrogen sulfide collects into amine liquid regenerator column top, under bottom reboiler heating condition, tower top goes out hydrogen sulfide, and the MDEA solution circulated be purified at the bottom of tower uses.MDEA solution regenerator overhead gas contains a large amount of hydrogen sulfide.
Patent 931210267 discloses a kind of benefit sulphur method of H 2 S-containing gas, is contacted with hydrocarbon ils by H 2 S-containing gas, by hydrocarbon ils dissolved hydrogen sulfide, then this hydrocarbon ils is transported to the reactive system of hydrotreatment, realizes mending sulphur.
Patent 201310374340.6 describes the H 2 S-containing gas that Sulfur-containing Sewage Stripping Tower stripping goes out, and directly compresses with membrane compressor, or by the method for hydrogen make-up compressor compresses to reactive system.
H 2 S-containing gas is dehumidified, liquefies and pumps into the method for reactive system by the introduction of this benefit sulphur method.
Prior art: the reaction feed F1 of hydrotreatment by after interchanger E1 heat exchange, then is mixed into process furnace H with the circulating hydrogen after circulating hydrogen compressor C supercharging, is controlled the temperature of reactor inlet by process furnace H.After reaction feed and circulating hydrogen carry out the series reaction such as hydrogenating desulfurization, denitrogenation, aromatic saturation, hydrocracking in several reactor R1 and R2, the reaction product of formation enters interchanger E1.After interchanger E1 and charging heat exchange, reinject water F2, for the ammonia in solubilizing reaction product, hydrogen sulfide, in storage tank D1, finally carries out the separation of Oil, Water, Gas.Wherein gas reenters compressor C as recycle hydrogen, and oil can send into fractionating section, has dissolved the sour water of hydrogen sulfide and ammonia, has discharged bottom storage tank D1, entered Sulfur-containing Sewage Stripping Tower T.
Summary of the invention
Hydrogen sulfide that analysis background technical agency continues source, as hydrotreatment the Sulfur-containing Sewage Stripping Tower that produced, or the amine liquid for desulphurization regenerator column that hydrotreatment is produced, the benefit sulphur that all can be used as hydrotreatment is selected.The sour water that discharges of preferred hydrotreatment is through the H 2 S-containing gas of stripping tower stripping gained, and because of the H 2 S-containing gas that its stripping goes out, impurities is considerably less, and pressure is also higher, is the hydrogen sulfide source of this benefit sulphur method the best.
For the sulphur of supplementary hydrotreater reactive system lacks, this benefit sulphur method, by above-mentioned preferred H 2 S-containing gas, respectively through dehumidifying, liquefaction, separatory and pressurization four steps, sends into reactive system.Make introductions all round these four steps below:
One, dehumidify.Hydrogenation type sour water, can obtain H 2 S-containing gas at tower top after stripping.Through sampling analysis, this gas sulfur hydrogen reaches more than 94%, but containing some moisture, methane, ethane, ammonia etc.The method removing ammonia is operation adjustment: generally enter purifying waste water after stripping in stripping tower teeming, to keep overhead gas hydrogen sulfide high purity, when analyzing discovery containing ammonia, only need carry a little and purifying the water yield greatly, just can dissolve wherein ammonia very well, because ammonia is very easily water-soluble.
This benefit sulphur method removes the method for moisture in H 2 S-containing gas three kinds: coalescent dehydration after (one) cooling.H 2 S-containing gas contained humidity, through cooling after coalescent, separable go out moisture.Such as 40 DEG C of hydrogen sulfide mixed gass containing saturated steam are cooled to 5 DEG C, more than 80% moisture can be removed.For preventing cooling apparatus from freezing, frozen block occurs, and what cooling temperature can be controlled at hydrogen sulfide saturated aqueous solution is above freezing.Maybe can adopt chilled brine (as lithium-bromide solution, sodium chloride solution etc.), directly contact with H 2 S-containing gas, to absorb wherein moisture.The object of this cooling step is dehydration, therefore is not cooled to make hydrogen sulfide content that the degree of liquefaction occur.(2) siccative absorption.Select silica-gel drier, or resistance to acid gas molecular sieve desiccant, all can adsorb to fall the moisture in hydrogen sulfide very well.Drying chamber can one be opened one standby, and slack tank can use factory's nitrogen, and after heating, adverse current is by siccative bed, takes away wherein moisture, realizes regeneration.(3) compound absorbs.The compound such as Vanadium Pentoxide in FLAKES, Calcium Chloride Powder Anhydrous has strong adsorption moisture ability.Hydrogen sulfide containing gas is passed into the storage tank bottom being filled with Vanadium Pentoxide in FLAKES, make it pass whole storage tank and flow out from top, in H 2 S-containing gas, namely water vapour absorbed by solid phosphorus pentoxide.It is phosphoric acid and metaphosphoric acid mixture that Vanadium Pentoxide in FLAKES forms liquid after absorbing moisture, can discharge from tank bottom.Vanadium Pentoxide in FLAKES supplements according to consumption is instant, or two storage tanks switch and use, and store enough Vanadium Pentoxide in FLAKESs, to ensure removing completely of moisture in gas.
Above-mentioned three kinds of methods, can choice for use, also can combinationally use, and such as allows H 2 S-containing gas, uses molecular sieve drying again, can extend the molecular sieve adsorption time, reduce the regeneration frequency after first cooling coalescent precipitation most of moisture.
Dehumidifying step sequence preferably cools coalescent rear drying, makes siccative with resistance to acid gas molecular sieve.
Two, liquefy.Pure hydrogen sulfide is gas in normal conditions.According to pure hydrogen sulfide saturated vapor pressure calculation formula IgP=-52.23B/T+C at different temperatures, then check in coefficient B=20.69, C=7.88, calculate the liquefaction pressure (gauge pressure) of hydrogen sulfide under differing temps as following table:
Visible according to upper table, the pressure of gas vulcanization hydrogen is higher, and liquefaction temperature is also higher.
In H 2 S-containing gas after this benefit sulphur method makes above-mentioned dehumidifying, the method for hydrogen sulfide liquefaction has two kinds: (one) pressurizes cooling.The heat-eliminating medium of such as factory's minimum temperature is recirculated water, and its temperature is 25 DEG C, and according to upper table, hydrogen sulfide sectional pressure reaches more than 2.5Mpa, can be condensed into liquid.Therefore can select the membrane compressor of zero leakage, H 2 S-containing gas is compressed to more than 2.5Mpa, then use factory's circulating water, namely gas vulcanization hydrogen become liquid, but the non-condensable gases such as methane are still gas.(2) directly freezing.Such as factory's Sulfur-containing Sewage Stripping Tower H 2 S-containing gas out, only have 0.3Mpa through dehumidifying postcure hydrogen dividing potential drop, according to upper table, need to be chilled to less than-34.5 DEG C, hydrogen sulfide could become liquid.Therefore by directly freezing for the H 2 S-containing gas after dehumidifying, refrigerant made by the refrigeration agents such as available liquid propylene, the hydrogen sulfide in H 2 S-containing gas is frozen into liquid, can obtains liquid curing hydrogen.Obviously, if factory's stripping tower gas out only has 0.1Mpa through dehumidifying postcure hydrogen dividing potential drop, need to be chilled to less than-57.3 DEG C, be limited to propylene refrigeration lowest temperature-47.7 DEG C, needing to change refrigerant is ethene, or other suitable refrigerants.
Liquefaction step sequence is preferably directly freezing, and this has larger flexibility of operation than pressurization cooling.On the other hand, the screw-type compressor selected for freezing, cools than pressurization the membrane compressor selected stable, also favourable to technology controlling and process.
Three, separatory.By the sulfide hydrogen mixture of above-mentioned post liquefaction, be incorporated in storage tank, carry out gravity settling, tank bottom enriched liquid hydrogen sulfide, the foreign gases such as methane originally can not liquefy, and are separated by storage tank, draw from tank top, can flare system be guided to, or the existing follow-up sulfur recovery processing unit of factory etc.This sulfide hydrogen mixture, also can select efficient wet cyclone, realizes thoroughly being separated of liquid curing hydrogen and foreign gas.Before noncondensable gas leaves separator, coalescer can be established, with the entrainment loss to liquid curing hydrogen during this non-condensable gas of emissions reduction.
The preferred storage tank of separatory, relies on gravity settling separation gas-liquid mixture, and equipment is simple, and be widely used, separating effect also meets processing requirement.
Four, supercharging.The first-selected pump of Liquid transfer.Consider very little (the general 500,000 tons/year of hydrotreaters of the liquid curing hydrogen amount of be injected into reactive system, flow 300L/h is enough), and consider that liquid curing hydrogen will be pressurized to the 8-25Mpa of reactive system from plant pressure about 0.3Mpa, according to factory scenario, high pressure plunger pump should be selected, cryogenic high pressure liquid delivery pump, maybe can select the hydraulic diaphragm metering pump of zero leakage.The liquid curing hydrogen collected after above-mentioned separatory is pressurizeed through pump, is transported to the reactive system of hydrotreatment.
The preferred hydraulic diaphragm metering pump of supercharging, this pump not only flow can directly read from the stroke of pump, can Long-distance Control, and zero leakage, has and leak Closed Drain facility during fault, and the hydrogen sulfide leakage of these safeguard procedures reply severe toxicity is very required.
The low temperature properties of liquid curing hydrogen after supercharging can be utilized, itself and hydrogen sulfide might as well be allowed to dehumidify or the suitable heat exchange of liquefaction step, after reclaiming cold, then send into hydrotreatment reactive system, also can not reclaim cold, be delivered directly to reactive system.Liquid curing hydrogen is in feeding reactive system process, and possible pipeline is long and by thermal evaporation, the hydrogen sulfide after gasification can continue to enter reactive system, realizes mending sulphur, does not hinder the enforcement of this benefit sulphur method, does not hinder and mends sulphur effect.
Liquid curing hydrogen injects the position of reactive system, can be the optional position entering reaction cycle hydrogen system.Preferably be injected into First reactor inlet, can directly make up needed for reaction like this, also help the corrodibility alleviated system miscellaneous equipment.
The beneficial effect of this benefit sulphur method is:
1, H 2 S-containing gas is passed through dehumidifying, be conducive to follow-up liquefaction, be more conducive to the etching problem of the Wet H2S environment alleviating follow-up pipeline equipment.
2, by liquefaction after H 2 S-containing gas dehumidifying, realize filling into of the hydrotreatment the purest hydrogen sulfide of reactive system, the hydrogen sulfide purity brought as DMDS or CS2 than factory's purchase note sulphur agent is high.
3, by hydrogen sulfide post liquefaction by pump delivery to reactive system, than with compressor investment and process cost on have saving.On the other hand, this benefit sulphur method, belongs to newly-increased part, can not have any impact when existing apparatus is transformed on existing utility.
4, this benefit sulphur method can select step sequence many, convenient according to factory's particular case adjustment or combination.Such as divide flow container, a simple container, can collect liquid curing hydrogen, is the place being separated noncondensable gas, takes into account the function of liquid curing hydrogen of having purified, or the inlet buffer of liquid curing hydrogen transferpump.
Embodiment
In fig. 1.
Embodiment 1: under heating condition at the bottom of the tower of Sulfur-containing Sewage Stripping Tower, in sour water, the component such as hydrogen sulfide, water vapour, methane flows out from tower top, forms H 2 S-containing gas.This gas enters to be filled with the storage tank D2 of resistance to acid gas molecular sieve desiccant, removes wherein after water vapour, then enters H 2 S-containing gas condenser E2.At the opposite side of condenser E2, utilize liquid propene to be heated vaporization, the low temperature of minimum-47 DEG C can be formed, realize the condensing cooling to H 2 S-containing gas.(refrigeration agent is not limited to propylene).After propylene gas vaporization, cooling after can drawing back supercharging again by screw-type compressor, cooling of expanding, recycle (identical with common refrigeration, not describe in detail).H 2 S-containing gas is through condensing cooling, and the hydrogen-cooled liquid that congeals into of gas vulcanization, enters storage tank D3 together with non-condensable gas methane etc.
In storage tank D3, liquid curing hydrogen and non-condensable gas methane etc. are settlement separate, and non-condensable gas is discharged through storage tank D3 top, and the liquid curing hydrogen of enrichment bottom storage tank D3, through hydraulic diaphragm metering pump supercharging, is delivered directly to the First reactor inlet of hydrotreatment.
In fig 2.
Embodiment 2: Sulfur-containing Sewage Stripping Tower T vapour proposes H 2 S-containing gas, enter the storage tank D2 bottom being filled with Vanadium Pentoxide in FLAKES, penetrate Vanadium Pentoxide in FLAKES bed from bottom to top, remove wherein after water vapour, flow out from D2 top, form dried H 2 S-containing gas.This gas through the membrane compressor C supercharging of zero leakage, then cools through water cooler E2, enters storage tank D3, and hydrogen sulfide forms liquid and is enriched in tank bottom, and non-condensable gas is discharged as methane etc. is enriched in tank top.Liquid curing hydrogen bottom storage tank D3, through hydraulic diaphragm metering pump supercharging, is delivered directly to the First reactor inlet of hydrotreatment.
The hydrogen sulfide working cycle of this benefit sulphur method is simply described: the sour water that existing hydrotreatment is produced below, through stripping tower stripping, tower top obtains H 2 S-containing gas, drying device is dry again, and enter liquid propene vaporizer, hydrogen sulfide is condensed into liquid, after storage tank is separated with non-condensable gas, be enriched at the bottom of tank, through volume pump supercharging, to the reactor inlet of hydrotreatment.After entering reactor, promoting catalyst activation recovering, flows out with reaction product again, rinsing, forming sour water through injecting water.Therefore, this benefit sulphur method is the recycle of hydrogen sulfide, thoroughly can solve the benefit sulphur problem of hydrotreater run duration.
As mentioned above, two kinds of embodiments of this benefit sulphur method are illustrated.Those skilled in the art, completely can according to bright sulfur liquefaction of hydrogen thermometer and factory's actual conditions, as the processing parameter such as temperature, pressure, purity of stripping tower top H 2 S-containing gas, and factory's coolant temperature, determine the institute's plus-pressure size under pressurization cooling step, or the cryogenic temperature, deep cooling medium etc. when determining freezing.Therefore, this benefit sulphur method does not limit the concrete technology parameter implementing this benefit sulphur method, because those skilled in the art are easy to according to specification sheets, determines factory's optimum parameter.But as long as do not depart from fact the inventive point of this benefit sulphur method and effect can have a lot of distortion, this will be readily apparent to persons skilled in the art.Therefore, such variation is also all included within the protection domain of this benefit sulphur method.