DE1948427A1 - Recovery of hydrogen sulphide and ammonia from aq - solns - Google Patents

Abstract

Recovery of hydrogen sulphide and ammonia from aq solns. G6A. Which may also contain light hydrocarbons under high pressures, by reducing the pressure on the system and stripping off the H2S from the soln., light hydrocarbons to remove in a distillation column, stripping off the ammonia in a second distillation of (cf. 25246R as DT 1948428) from the aq. product at the bottom of the first column, then partially condensing the ammonia-rich gases at the top of the column whereby an ammonia-rich gas and condensate are obtained. Some of the ammonia-rich condensate is combined with the untreated aq. soln. (process I), some of which may contain light hydrocarbons, and which are removed in gaseous form in a degasser by lowering the pressure on the combined aq. soln. (process II). This combined aq. soln. is then led into the first distillation column, (process III). From 5 minutes to 24 hrs. (pref. is not 1hr, esp. pref. 3-24 hrs) are allowed to pass between process II and process III.

Description

Process for the separate production of hydrogen sulfide and ammonia from aqueous solution.

The present invention relates to a method for obtaining H2S and NH3 from an aqueous solution of H2S, NH3 and light hydrocarbons under superatmospheric pressure, with H2S and NH3 separated from an H2S stripper or an NH3 stripper, which has improved control and stability properties and in the case of the aqueous solution of the charge with a high H2S content can be modified in a more advantageous manner by having (1) one in the overhead system NH3-rich and H2S-poor condensate flow generated by the NH3 stripper with the aqueous solution of NH3, H2S and light hydrocarbons combined, then (2) light hydrocarbons in the form of gases by reducing the pressure on the combined solution removed, (3) a residence time for the combined Solution vorsient and then (4) the combined aqueous feed stream H2S stripper feeds.

In many previously known Hydro @ conversion processes that are used in Hydrocarbon oils, shale oil, heavy oil sands, etc. are applied, and for the catalytic hydrogenation, the hydrofining process or hydrodesulphurisation and hydrocracking are typical examples, H2S and NH3 are obtained as a result of a Reaction of hydrogen with sulfur and nitrogen compounds that are in the oil are included. Sometimes this is the conversion of the sulfur and / or nitrogen compounds the desired implementation, while in other walls it is merely a random one Implementation acts. A typical process will usually use liquid Hydrocarbon oil containing nitrogen and sulfur compounds and recycled hydrogen-rich gas and additional hydrogen at elevated temperature and elevated pressure through a reaction zone which usually contains a catalyst, out, wherein at least a part of the hydrocarbons is evaporated. Here you get a mixture of evaporated hydrocarbons, hydrogen, H2S and NH3 as gas emerging from the reaction zone. The outflowing mixture came, however also contain heavier hydrocarbons that are liquid under reaction conditions are. The exiting reaction mixture is cooled to remove evaporated hydrocarbons to condense, which removes the liquid hydrocarbons from the hydrogen-rich ones Circulating gas separated @nnt @@ r @@@, which then is part of the procedure wi @@ @v rwechsel @ t will.

If the outflowing reaction mixture contains both H2S and NH3, so, as @ was found, after A @ cool to temperatures below about 149 ° C React H2S and NH3 with the formation of salts, which sometimes form a lump in the currency exchangers and line @ are problematic. To such filing -Run @ en to wash out and / or to reduce the clumping of the same, was Water in the upward flowing stream from the heat exchangers the reaction products are injected. Such a splash of water can a large amount of the formed NH3 can be removed if fairly large wasse @@ tight sufficient to dissolve the NH3.

In a typical hydroconversion process, such as, for example when treating with hydrogen (Hydrot @@@ tin @ verf ren @ ober dem @ v @ rokrecken, there are considerable amounts of light hydrocarbons in the end of the reaction gases and hydrogen at -wese @. After @ @ H2S and NH3 ore washed out of @@@@ oil si @@, part of these light coal materials and a small part of hydrogen in the water phase, especially when washing under high Printing takes place. Many hydroconverting processes involve washing under one Pressure from 35 to 352 atmospheres, typically from 70 to 210 atmospheres. For example a gas oil with hydrogen treated, that's how you cool that from hydrotreating -device outflowing mixture by heat exchange to a temperature between about 38 and 66 ° C under a pressure of 140 atü. Since the water with that from the hydrotreating reactor outflowing gaseous mixture is mixed under high pressure, dissolve before the effluent mixture is cooled to 38 to 60 ° C, significant amounts of light Hydrocarbons such as methane, ethane, pro @ an, butane, etc.

in the water.

These light hydrocarbons as well as the dissolved hydrogen can removed from the aqueous phase before the treatment to remove H2S and NH3 are used by reducing the pressure on the aqueous solution. It is desirable to retain H2S in the aqueous solution when the pressure decreases is because (1) H2S is an impurity in the light hydrocarbon vapors and (2) H2S is preferably used as valuable in a single Concentrated Stream By-product obtained in the subsequent H2S and NH3 recovery process. In In many cases, however, the content of H2S in the aqueous solution is that formed - for example in the overhead system of the stripper or the fractionation devices for hydroconversion processes - too high to essentially completely remove the H2S keep in solution when the pressure is reduced.

Another problem that the previous method for separate Extraction of H2S and NH3 from contaminated water, which contains H2S and NH3, is created, lies in the difficulty of even and constant control of the extraction strippers used by H2S and NH3. The one in U.S. Patent 3,335,071 The method described can be an aqueous solution of H2S and NH3 such as are treated as follows: (a) Stripping the aqueous NH3, H2S solutions in a first Stripping distillation column to produce an H2S-rich vapor and to obtain an NH3-rich aqueous solution as residue; (b) Stripping the NH3-rich aqueous bottoms product in a second distillation column to an NH3-rich Receive steam as an overhead product; (c) partially condensing the vapor NH3-rich overhead to an NH3-rich vapor and an NH3-rich aqueous Obtain overhead condensate, and (d) recycle part of the NH3-rich, Aqueous overhead condensate in circulation to the first distillation column (H2S stripper).

The return of the NH3-rich overhead condensate to the circuit the H2S stripper is very desirable for some purposes, but fluctuations tend to occur the NH3 content in this stream, temporary congestion during the H2S stripping process to cause.

These are based, as is assumed, in part on the considerable, Amounts of NH3 contained in the circuit, based on the amount of NH3 in the feed for the H2S stripper. However, it is not entirely understandable why in some Cases when the NH3 level increases in the NH3 stripper overhead condensate, a large one "Bubble" of H3 rises in the H2S stripper, which increases the purity of the H2S overhead material and requires correction of the overhead control in the stripper power. Also, as a result of the increase in the NH3 content of the NH3 stripper overhead condensate higher pressures required at the bottom of the H2S stripper if at a given Temperature is being worked. Since these changes occurred relatively quickly, was a smooth and smooth control of the H2S stripper and NH3 stripper not always achievable.

In summary it can be said that according to the previously known Process considerable amounts of H2S from the aqueous solution required for a separate Extraction of H2S and NH3 to be treated can be lost if the Pressure on the aqueous solution is reduced to light hydrocarbons and / or Hydrogen, which are dissolved in the aqueous solution of N S and, to remove. Furthermore, in the case of the previously used for the separate extraction of H2S and Procedure Difficulty trying to work smoothly and consistently the H2S and NH3 strippers. By the method of the present invention these difficulties are essentially overcome.

The present invention is now a method for the separate Extraction of H2S and NH3 from a first aqueous, from H20, H2S, NH3 and light Hydrocarbons existing solution at above atmospheric pressure by degassing the same by reducing the pressure, whereby light hydrocarbons are removed, and a second solution containing aqueous H2S and NH3 precipitates; Stripping from H2S from the second aqueous solution in a -first distillation column, wherein an H2S-rich overhead stream and an aqueous bottoms stream with reduced H2S content is obtained; Stripping of NH3 from the aqueous bottom stream in a second Distillation column, whereby an NH3-rich overhead gas precipitates and partially Condensation of the NH3-rich overhead gas to obtain an NH3-rich gas and an NH3-rich overhead condensate, characterized in that a) at least a part of the NH3-rich overhead condensate combined with the first aqueous solution, to obtain a combined aqueous solution then b) at least a portion of the hydrocarbons contained in the first aqueous solution in a degassing zone removed in gaseous form by reducing the pressure on the combined aqueous solution, to obtain this second aqueous solution, and then: c) the second aqueous solution Solution in the erete Des, tillatioj0skol oime directs.

If one proceeds in this way, a direct return is avoided of the NH3 stripper overhead condensate in the circuit to the H2S stripper and it becomes achieves improved control and consistency of the H2S stripper. aside from that enables the recirculation of the NH3-rich overhead condensate from the NH3 stripper to the degassing zone, while retaining H2S in the aqueous phase light hydrocarbons and / or hydrogen from the aqueous ones containing H2S and NH3 Charging can be removed in gaseous form.

It is believed that the improved durability of the H2S stripper is largely achieved by the direct recycling in the circuit of the Avoids condensate rich in NH3. According to the present invention, the becomes NH3-rich Condensate is recycled to the degassing zone where there is an equilibrium reached with the net input amount to the H2S stripper or is close to it; Fluctuations in the feed composition are due to the additional residence time dampened. A residence time of at least five minutes after combining is desirable of the aqueous streams and prior to introduction into the H2S stripper. Much more than that becomes a residence time of one hour to three hours for the combined gross input streams of the NH3 -rich recycle condensate from the NH3 stripper and the aqueous H2S-NH3 net feed solution preferred. Even more, a residence time of about 3 to 24 hours or longer preferred for the combined, i.e. gross input flows.

A residence time for the NH3-rich recycle condensate before the introduction to the H2S stripper is in contrast to the previous process, in which the circuit of the NH3-rich condensate connects the H2S stripper directly with clem NH3 stripper connected, so that impairments in one of these strippers often the could affect another stripper.

It has also been found that if a residence time is used, the oil will from about 24 hours or more substantially entirely from the sewage flow can separate so that the strippers are kept cleaner. Contain the feed streams Wastewater from liquid catalytic cracking units makes the residence time possible of about 24 hours or longer also a conversion of hydrogen cyanide acid, which are readily present in such wastewater streams, to thiocyanate. the Conversion of the hydrogen cyanide to thiocyanate contributes to corrosion problems in the strippers to a minimum.

It was found that when the NH3 overhead condensate is recycled large amounts of H2S fed into the circuit in the process according to the invention without excessive H28 losses in the light hydrocarbons and / or hydrogen can be treated from the degassing stage. Under most conditions it is the H2S content of the gases from the degassing stage is very low. The degasser exhaust can be used as refinery fuel gas, as only a very small amount of SO2 Is generated by burning the gases. Air pollution is therefore significant degraded.

A number of streams containing H2S and / or NH3 can be added according to the Methods of the invention are treated, but it is preferred to use a vessel or to provide a device for curing dwell and mixing the NH3-rich ionic densate and the net feed to the present process to allow. For example, an intermediate container can simply be used without removing the light hydrocarbons or a degassing device to remove the light Hydrocarbons all one: at least one of the feed streams for the invention Procedures are used. In the more common case, a degassing stage is necessary, which in most cases results in a loss of H2S and / or extra expenses for removal of H2S from the light hydrocarbons if the process according to the invention is not applied. As indicated above, the H2S content can be the net feed streams be relatively high in the present process, but still in Questions come without major ii2 losses or H2S contamination in the exhaust gases occur in the degassing zone. The return of the NH3 stripper overhead condensate in the circuit to the degassing zone serves to hold back H2S in the aqueous phase.

It has been found that in the process of the invention by The advantage is to use two degassing stages. This causes further H2S losses in the light hydrocarbon streams removed from the aqueous solution when the pressure on the aqueous solution in the degassing zone is reduced will, reduced to a minimum. The first degassing stage is a high pressure degassing stage, at which the pressure is kept between 3.5 and 3.5 atmospheres.

Preferably the pressure is maintained at about 4.9 to 14.1 atmospheres. the aqueous solution of the liquid phase from the high pressure degassing stage is now too passed a low pressure degassing stage.

Aqueous streams containing H2S and / or NH3 together with eringen quantities more easily contain hydrocarbons, the latter being relatively lower as a result Pressures, for example 0.7 to 7 atmospheres, are dissolved in the aqueous solution, leads one advantageously-way to the process according to the invention in that one such Streams combined with the aqueous solution passed to the low pressure vent. The low pressure degasser is at a pressure between 0 and 3.52 atmospheres, preferably held between 0.07 and 0.7 atm.

A preferred embodiment is shown schematically in the drawing the method according to the invention for the separate recovery of H2S and NH3 shown, two degassing stages are used. Based on the drawing, the inventive Procedure explained in more detail below.

An aqueous stream of water containing H2S and NH3 is passed through line 1 fed to the device. In a preferred embodiment, this is aqueous Feed stream obtained by taking that from a hydrocracking reactor The material flowing out is mixed with water at a pressure of about 140 atmospheres or brings in touch. As already mentioned above, this contact name will be therefore carried out to remove ammonia and H2S from the effluent from the hydrocracking reactor Remove material. Because of the latter 'substantial amounts of hydrogen and light Contains hydrocarbons, the aqueous solution that forms will settle, except of H2S and lH3 from hydrogen and light hydrocarbons.

In the method according to the invention, this aqueous solution is with combined with the recirculated NH3- -rich aqueous stream, the from from the overhead of the NH3 stripper, as detailed below is described. The NH3-rich aqueous solution is circulated through line 2b returned.

A stream rich in H2S emerging from the overhead material of one of the stripping distillation columns that was used to remove light hydrocarbons from the hydrocracker effluent product is used is fed through line 2. To the many H2S-rich streams that can be treated in the method according to the invention, include those streams derived from liquid steam-trip hydrocarbon streams can be derived from hydrotreating or hydrofining processes. These outflowing liquid hydrocarbons contain H2S and light hydrocarbons', the stripped or distilled off. These overhead vapors from stripper or distillation columns, obtained from the stripping process contain substantial amounts of H2S that are in significant Extent to dissolve in the water that forms when the overhead inateri% i is partially condensed. Often stripping is used in the case of low pressures, for example at 0.35 to .5 atm. in the overhead accumulator carried out. In this case the overhead condensate streams can flow through line, 7 are fed to the method according to the invention. It is especially important to be light Remove hydrocarbons from overhead condensate streams when the hydrogen sulfide, which is removed from the H2S stripper through line 15, is desired in a highly pure form will. Should the hydrogen sulfide, for example, be used as a feedstock for a Claus process are used to produce sulfur, it is desirable that the H2S stream contains less than 0.1 Vol.jO hydrocarbons.

In some cases it is made from hydrotreating or hydrocracking Leaking hydrocarbons - stripped or fractionated to H2S and light To remove hydrocarbons at a pressure above 3.5 atv. In the U.S. Patent For example, 3,356,608 describes a process in which gas oil and hydrogen brought into contact with a sulfur-active hydrogenation catalyst and the outflowing Hydrocarbon stream after removal of the circulating hydrogen at pressures above 10.5 atmospheres are steam stripped. After condensing the overhead material from the stripper an aqueous phase forms, which, compared with that in the presence of H2S at Aqueous solutions formed at lower partial pressures of H2S, very rich in H2S can be.

The combined streams 1, 2 and 26 are through management 3 introduced into the high pressure degasser 4. In order to have low H2S contents in the exhaust gases The high pressure degasser is preferably operated to a pressure of about 13 ° atü and a temperature of about 270C. By lower pressures and higher Temperatures, the H2S content rises in the exhaust gases. Light hydrocarbons and Hydrogen is released through line 5 from the top of the high pressure degasser removed. Used at a pressure of about 7 to 14 atmospheres and a temperature of 27 ° worked up to 38 ° C, the H2S content of stream 5 is generally below 3 % By volume.

Used at a high pressure and low temperature according to the invention Process in Eo chdruck-: De-tgaser worked, so the H2S content can be between approx 0.1 and 2.0% by volume are kept. This way stream 5 has a very low one H2S content and is generally suitable as refinery fuel gas. i) ie partially Degassed aqueous solution is discharged from the bottom of the high pressure degasser through line 6 deducted.

An aqueous solution of H25, NH3 and small amounts of dissolved hydrocarbons, obtained as overhead condensate from a hydrocarbon stripper, the operating at an overhead pressure of about 3.5 atmospheres is introduced through line 7. The combined aqueous streams in lines 6 and 7 are passed through line 8 led to the low pressure degasser 9.

The low pressure degasser is preferably at a pressure of about 0.14 atm. Light hydrocarbons are in line 10 from the low-pressure degasser withdrawn and an. aqueous solution of H28 and NH3 is from the bottom of the degasser Line 11 withdrawn. Of the The H2S content of stream 10 is generally less than about 4% by volume when working according to the method according to the invention will. The percentage of H2S in the low pressure degasser exhaust can be further, for example be reduced to an area for the high pressure degasser because of the Increases the amount of NH3-rich kodensate, decreases the temperature and increases the pressure. In most cases, most of the exhaust gases, i.e. predominantly hydrogen and methane, vented into the high pressure degasser. Usually about 80 to flow 90% by volume of the dissolved gases in the high-pressure degasser. Only a proportionate one A small amount of H2S is therefore withdrawn from the low-pressure degasser with the exhaust gases. According to the present invention, therefore, almost all of the hydrogen sulfide remains in the aqueous phase so that it can be recovered as an overhead stream from the H2S stripper can be.

The aqueous solution from the low-pressure degasser is fed into the intermediate feed tank 12 introduced, where a residence time of preferably 3 to 24 hours is provided is. The intermediate container 12 should be made of a floating layer or of inert gas Existing coverage exist. If air is left in contact with the aqueous solution kolrunen, the hydrogen sulphide oxidizes and forms free sulfur.

The aqueous solution is discharged from the intermediate container through line 13 withdrawn and introduced into the H2S stripper 14. As a result of the heat supply in the At the bottom of the H2S stripper, hot, upward-flowing vapors develop, which, in addition, serve to remove the hydrogen sulfide from the stripping aqueous solution. A cool stream of water is passed through line 16 into the upper part of the H2S stripper introduced to create a downward flowing aqueous stream that serves to to fractionate the ammonia from the hydrogen sulfide. A relatively pure one H2S stream is withdrawn through line 15 from the top of the H2S stripper. The NH3 content in this HSS stream is usually less than 2% by weight, normally as low as a few tenths of a percent; the H2S stripper conditions are preferred kept such that one has an NH3 content of less than 100 parts / million, for example Gets 10 to 30 parts / million.

An aqueous solution that is rich in NH3, but still essential Contains amounts of H2S, is withdrawn through line 17 from the bottom of the H2S stripper.

This stream is directed to the NH3 stripper 18. Through heat conduction Hot upflowing gases are generated at the bottom of the NH3 stripper. These serve to strip NH3 and H2S from the less aqueous solution fed to the NH3 stripper. A purified water stream is withdrawn from the bottom of the NH3 stripper through line 19.

A steam stream of H2O, NH3, and H2S is generated from the top of the 14H3 stripper pulled through line 20. The process conditions in the NH3 stripper are controlled so that the amount of H2O in the steam flow in line 20 is regulated, so that when this vapor stream partially condenses in the condenser 21, that which is formed liquid condensate withdrawn from the condenser through line 22, a very big Fraction @es H2S present in the overhead system contains. In this way, the ammonia withdrawn as gas in line 24 becomes essentially freed from H2S.

The H2S content in the NH3 gas is generally less than about 1 to 2% and can be reduced to 0.1 to 0.5% by volume of H2S. The condensate, formed by cooling the NH3 stripper overhead gases in condenser 21, is rich in NH3. Typically the ratio of NH3 to H2S is in that the reflux drum 2 @ withdrawn condensate through line 25 between 10: 1 and 2: 1. The ratio of NH3 to H2S is preferably 3: 1 to 6: 1 on a molar scale Base. A portion of this NH3-rich condensate is passed through line 27 to the NH3 stripper refluxed to a cool, downward flowing liquid in the upper part of the NH3 strioper. According to the method according to the invention, a second Amount of NH3-rich condensate fed back through line 26 1L circuit, to with the net feed material fed to the process through lines 1 and 2 to be united.

In the present invention, it is preferred to reduce the amount of NH3-rich condensate that is recycled, as well as the ratio of NH3 to H28 in the circuit so that the ratio of NH3 to H2S of the combined streams that are fed to the high pressure degasser, at least 1.1: 1.0 on a molar basis. For currents that are more than 1 or 2% dissolved Containing H25 and 1H, it is preferred to add more NH3-rich circulating condensate use so that the ratio of NH3 to H2S (calculated as separate types) is at least 1.2 to -1.0, and in many Cases it is preferred to have one and a half to about five times as much NH3 as H2b.

Example 1: This example explains the benefits that can be achieved when the inventive method in the treatment of aqueous Flows are applied that add large amounts of H2S in proportion to NH3 light hydrocarbons and / or hydrogen, due to high pressure in the aqueous Electricity included.

A solution of about 446 kg H2S, 234 kg NH3 and about 21.5 liters Hydrogen plus minor hydrocarbons, dissolved in 12.6 kg H2O, are thereby produced obtained by mixing a material flowing out of a hydrocracking reactor with water washes. The stream leaving the hydrocracking reactor that is washed with water has a temperature of about 121 ° C and a pressure of 87.9 atü. The one on this The aqueous stream obtained in this manner is introduced into the process through line 1, which is explained schematically in the drawing, with the exception that there is no NH3-rich circuit condensate to the high-pressure degasser. A However, some of the NH3-rich overhead material from the NH3 stripper becomes directly too returned to the H2S stripper in the cycle.

An aqueous solution of 12,700 kg H2O, 198 kg H2S and only Trace amounts of NH3 are collected as overhead condensate from a fractionation column by doing Obtain fractionation section of the hydrocracking unit. This stream is introduced into the process through line 2. At this first one Stage is the NH3-rich condensate from the upper part of the NH3 -Stri @@ @ directly in the Circuit led to the H2S Stri @@ er. The currents above and those obtained Streams corresponding to the numbered streams shown in the drawing become summarized in the following table: Table I: Stream No. H2O, kg / hour. H2S, kg / hour NH3, kg / hour

1 12,614 446 234 2 12,700 198 0 3 25,320 644 234 5 0.90 177 0 8 25,319 467 234 10 0.45 4.54 0 11 25,318 463 234 15 2.72 458 0 24 1.30 2.27 226 The United Streams 5 and 10 contain about 21.5 liters of hydrogen plus light hydrocarbons fabrics.

When using the method according to the invention, identical Streams 1 and 2 led to the method explained schematically in the drawing. aside from that some of the condensed overhead material will be removed recirculated to the NH3 stripper 18 through line 26 to the high pressure degasser. This recycle stream is rich in NH3 relative to H2S. The number of moles for NH3 in the recycle stream is 26.2; the total number of moles for H2S is 8.7, so that a molar ratio of NH3 to H25 of e about 3.01 results. In the NH3 circuit through line 26 there is a sufficient amount of NH3 so that it levels out combined streams in line 3 had a ratio of NH3 to H2S on a molar basis of more than 1.0. Preferably the ratio of NH3 to H2S is in stream 3 held above 1.1. In this example reads the ratio of NH3 to H2S at 1.22. The feed streams and obtained streams are combined below - contains: Table II: Stream No. H2O, kg / hour. H2S, kg / hour NH3, kg / hour

1 12. @ 14 446 234 2 12,700 198 0 26 258 67 202 3 25,600 711 a35 5 0.45 0.90 0 8 25,602 710 436 10 0.45 0.90 0 11 25,600 708 436 15 2.72 638 0 24 1.36 2.27 226 The combined streams 5 and 10 contain approximately 21,523 Liters of hydrogen plus light hydrocarbon gases.

As from comparing Streams 5 and 10 in Table II with the Streams 5 and 10 in Table I, the H2S losses are drastically reduced.

When using the method according to the invention, the H2S losses from 181 kg / h (Table I) to 1.81 kg / hour. (Table II) reduced. The inventive -Methods thus causes a reduction in the amount present in the withdrawn gases H2S by a factor of 100 in this example. The return in the cycle of NH3-rich overhead condensate from the NH3-Stri @@ it is therefore of particular advantage, when feed streams are added containing relatively large amounts of H2S in the Have compared to NH3. Are the H2S concentrations in the net feed streams lower, the advantage is correspondingly reduced, but in general ' the H2S loss - reduced by a factor of at least five. Also serves the return in the circuit of the NH3-rich condensate is still up to one to a certain extent to retain hydrogen sulfide in the aqueous phase, see above that this can be obtained through line 15 as a uniform product stream. Furthermore, the return in the circuit of the NH3-rich condensate points to the degassing section instead of the direct route to the H2S stripper has the very important advantage, that the control resistance of the H2S stripper as well as the NH3 stripper improves will.

Claims (7)

Patent claims: 1. Process for the separate production of hydrogen sulfide and Ammonia from an aqueous solution, which consists of H20, H2 and NH3 and the possibly. contains light hydrocarbons at above atmospheric pressure, by degassing the light hydrocarbons contained under pressure aqueous solution by pressure reduction, and / or stripping of H28 from the none Aqueous solution of NH3 and H2S containing light hydrocarbons in one first distillation column, stripping of NH3 from the aqueous bottom product of the first distillation column in a second distillation column and partial Condensation of the resulting NH3-rich overhead gas, with an NH3-rich Gas and an i'H3-rich overhead condensate accumulates, characterized in that a) at least part of the rich overhead condensate with the aqueous starting solution combined to give a combined aqueous solution, optionally b) at least part of the if necessary in the aqueous starting solution. contained light Hydrocarbons are removed in gaseous form in a degassing zone by increasing the pressure reduced to the combined aqueous solution, and c) the combined, no easy Where: hydrogen Containing aqueous solution in the first distillation column directs. 2. The method according to claim 1, characterized in that between the stage (b) and (c) respectively. (a) and (c) a residence time of at least 5 minutes for the combined allows aqueous solution to enter. 3. The method according to claim 2, characterized in that the residence time is at least an hour. 4. The method according to claim 2, characterized in that the residence time is about 3 to 24 hours. 5. The method according to claim 1, characterized in that - if the combined aqueous solution contains light hydrocarbons - this solution first in a high pressure degasser at a pressure between 3.5 and 35 atm and then degassed in a low pressure degasser at a pressure between 0 and 3.5 atmospheres. 6. The method according to claim 5, characterized in that the gross coverage of the high pressure degasser has the following components: a) an aqueous solution of H2S, NH3, light hydrocarbons and hydrogen obtained thereby is that one of the outflowing material from a Hydroconversion process brings it into contact with water at a pressure of at least 35 atmospheres; legs Aqueous solution consisting of H25 and light hydrocarbons, in which the H2S content is such that the combined streams (a) and (b) have a molar ratio from NH3 to H2S of less than 1.1: 1.0, c) an amount of NH3 in the NH3-rich Condensate, which is returned in the circuit from the overhead material of the NH3-Stri @ pers is sufficient to ensure that the combined streams (a), (b) and (c) have a molar Have a ratio of NH3 to H28 of at least 1.1: 1.0. 7. The method according to claim 6, characterized in that the dem Low pressure degasser fed feed from an aqueous solution of H2S and light hydrocarbon obtained by mixing H20, H28 and light Hydrocarbons epi cLit, em pressure of below 3.5 atmospheres was obtained.