DE1951278A1 - Improved process for removing CO2 and / or other clean gases from gas mixtures - Google Patents

Description

DR. ELISABETH JUNG, DR. VOLKER VOSSIUS. DIPL-ING. GERHARD COLDEWEY MONKS 23. CLEMENSSTRASSE 30. TELEPHONE 348087. TEtEQBAMM ADDRESS: INVENT / MONCHEN. TELEX 5-29688

E 786 / MÜ / Vo / J / k

Flat share 28 '- Flat share 2Ga

10.0k! J969

VBTROCOKE COKAPUANIA S.p.A., ·

Venezia Porto Marghera / Italy and

Giuseppe GIAMMARCO,
Venice, Italy

¹¹ Improved procedure for removing · CO2 and / or other acidic gases from gas mixtures ¹¹

Priorities: October 15, 1968 an; d

April 19, 1969

both Italy registration no. : 53 496-A / 68 and

51 5O5-A / 69

The invention relates to methods for removing acidic Impurities such as COp, HgS or HCN, separately or together, from gas mixtures. The processes consist of an absorption phase in which the gas mixtures with absorption solutions are more suitable Type and chemical composition are washed, and a regeneration phase in which the absorption solutions regenerated by heating them to boiling point and removing the absorbed impurities.

It is known to be beneficial in most cases and it is very often necessary that the temperature in the absorption

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tion phase is lower than the temperature in the regeneration phase, during which the solution is heated to the boiling point. As a result, because of this temperature difference, it is of fundamental importance that the heat used to heat the absorption solution to the boiling point (i.e. the amount of heat the boiling regenerated solution that arises in the regeneration phase) in the process beneficially used and is not released into the environment unused by means of a cooling device, which is also expensive, among other things.

The utilization of the heat content of the boiling, regenerated solution has heretofore been in various ways by various means Cycle processes common in industrial practice are brought about. Particularly well-known cycles are the conventional, the isothermal and the optimal cycle.

It is known that the absorption temperature in the conventional cycle is noticeably below the regeneration temperature, _ It is also known that when using an ethanolamine solution (MEA, BEA, TEA) or other solutions of organic compounds, the absorption temperature is close to the ambient temperature - this applies to both absorption from GO ₂ as well as from H ₂ S. It is known that in this cycle the> heat content of the boiling, regenerated solution is used to heat the used solution before it enters the regeneration device. For this purpose a heat exchanger and a cooling device are used, which are arranged between the absorption and regeneration orrißhinmg

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are. However, it is known that the heat exchangers are very good is costly and in itself, a considerable percentage Represents a proportion of the cost of the plant.

It would therefore be very desirable to change and improve the conventional cycle in this way, which is also one of the goals of the Invention is \ that at temperatures in the absorption phase, which are very close to the ambient temperature, the heat exchanger can be omitted.

The isothermal cycle utilizes the heat of the boiling, regenerated ones solution not. It is known that the use of a heat exchanger is circumvented in this process in that .the boiling, regenerated solution directly to the absorption device is fed. However, this advantage is canceled out by the fact that the absorption temperatures are high and generally above the so-called optimal temperatures (These are defined below; they correspond to the volume minimum and the minimum height of the absorption column) lie. Likewise, the advantage is canceled out by the fact that the heat content of the boiling, regenerated solutions depends on the heat loss in the absorption device finally by means of the COp cooling device (or the other acidic gases) to the Environment. The cooling device must be corrosion-resistant because of the corrosive properties of the acidic gases Steel, which causes an increase in the cost of the apparatus.

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The subject of the invention is therefore a change and Isothermal cycle improvement.

• * · ■

The optimum cycle is characterized in that the seven 'Dende regenerated solution Teicht is cooled, generally nen to 85 - 9O ⁰ C in Pall yon mineral solutions, such as solutions of simple and activated carbonates so that the solution as it passes through the absorbing device of a temperature after the heating by the reaction heat and by the heat content gas to be purified of at least 98 - reaches 105 ⁰ C, sufficient to bring the solution directly without

Feeding a heat exchanger to the regenerative soldering device · This has the advantage that the heat exchanger of the conventional cycle is no longer necessary. _{Another advantage is that the heat generated by running the cycle is not completely removed by means of a CO 2} cooler made of corrosion-resistant steel, as is the case with the isothermal cycle, but is partially removed by a cooling device of the regenerated solution, which, however, is made of cheaper carbon rod is built and is also less expensive because of a more favorable temperature difference.

In addition, as is well known, one of the characteristics of this cycle is that the absorption temperature changes to the so-called Optimal temperatures (hence the name "optimal cycle") approaching. At this point it should be remembered «that an increase in temperature reduces the exchange coefficient Kga of the alkali carbonate solutions improved, while on the other hand the vapor pressures of

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and HgS increase. These opposing effects of temperature rise determine the so-called optimal temperature which according to the definition of Sherwood the best absorption conditions, i.e. the minimum volume and the minimum height of the * absorption column coincide. The optimal cycle can be the Utilize the heat of the boiling, regenerated solutions that the cooling device of the solution in practice by a Heat exchange recovery system, in which the water for the boiler supply is heated, is replaced.

The subject of the invention is the change and improvement

»The optimal cycle while maintaining the ones described above Properties so that the amount of heat of the boiling, regenerated solutions to a greater extent in the cleaning process itself is recovered.

The invention has the goal> the amount of heat of the boiling, regenerated Recycle solutions to the extent of regeneration of the solutions themselves to improve. In addition, it is the aim of the invention to provide the heat supply necessary for the cycle to run to decrease.

Another object of the invention is to wholly or partially the heat exchanger between hot, regenerated solution and cold, used solution to eliminate in those cases where the absorption is at a lower temperature than that Regeneration is running. Another object of the invention is θθ, reduce the cost of the plant considerably.

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The invention is based on the fact that the heat content of the hot or boiling, the regenerated solution in the form of a vapor stream is withdrawn, together with the vapor stream is used \ m essential to withdraw a portion of the CO2 and / or other acidic gases of the solution itself, whereby_the auamasa of regeneration is improved. "

The withdrawal of the steam stream can be carried out by various means below described methods can be accomplished. These methods consist mainly of "that" the solution of a pressure reduction or subjected to treatment with inert gases.

The withdrawal of the steam flow is facilitated by the fact that the Electricity is directed into an area of colder temperature, where the steam condenses. The steam is then preferably brought in in close and direct contact with the coming from the absorption column ^ colder, used solution, this is heated. In this way the heat content of the hot, regenerated solution over to the cold, used solution. This is easier and cheaper than with the expensive, In the previous technology used heat exchanger in front of it, which can be omitted. In addition, the heat is better utilized, since, as stated below under e), a larger amount of Cöp than when using a heat exchanger is eliminated beforehand.

Another part of the door consists of the 'Ta-Ssach®', which is the transition of the vapor from one solution to another spontaneously and without

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Energy consumption goes on until the two solutions have the same temperature «or, more precisely, have reached the same vapor pressure *

In the following, more detailed information is given about the withdrawal of the steam stream from the regenerated solution and its utilization to remove part of the CO ₂ contained in the solution itself and / or the other acidic gases.

This is one of the most important advantages of the invention, namely because the best possible regeneration achieved here in the previous. Technology requires the supply of approximately twice the amount of heat to the regeneration column would have.

The improvement of the regeneration in the regenerated solutions through the heat content of the solutions themselves is new. and in not known to the prior art. Also this is Improvement surprising, also because of that, because of the solution The heat withdrawn and used for improvement can in some cases also be less than the heat that is consumed would normally have to feed a conventional regeneration column in order to achieve the same effect.

To improve the degree of regeneration, it is necessary ¹ that the alkali metal carbonate solutions contain particularly effective activators, preferably activators of the acidic type, such as As ₂ O, glycocolla (amino acids) and the like. In addition, it is necessary

009829/1354

agile that the extraction of steam from the hot or boiling, regenerated solution with the special devices described below, or with the other devices which- the subject of the Italian Patent Application No. 51,679 are. .

1. A very simple and easily applicable method for Withdrawal of the steam stream from the hot or boiling, regenerated solution consists in removing the regenerated solution himself through. Extend pressure reduction from above atmospheric pressure to a pressure close to atmospheric pressure leaves.'

This case arises in industrial practice when the regeneration column operates under excess pressure in order to produce COg under pressure, which is advantageous if the COg is to be used to produce urea. In general, a pressure of about 2 to 2.5 ata is chosen. In this case, a simple or activated alkali metal carbonate solution boils at a temperature of about 125 to 130 ^° C. and emerges from the regeneration column at this temperature. .

An analogous case occurs when a Tray column is used in which the trays are known to cause a pressure increase in the lower part of the regeneration column and consequently cause the boiling temperature of the solution to rise. In these cases the withdrawal of the Steam flow from the regenerated solution simply by

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allows the solution to expand even to atmospheric pressure, with no mechanical or similar devices necessary Bind, the y-e, however, with the others, described below Cases are required.

The regeneration effect that is achieved when the steam flow is withdrawn Reached from the solution, was the subject of special studies in which the. best known and most important absorption solutions were used, such as potassium arsenite solutions,

Glycol
alkali carbonate solutions activated by / addition or by addition of diethanolamine (DEA), simple potassium carbonate solutions, monoethanolamine solutions or ⁴ other ethanolamine solutions.

When examining these solutions, the temperature was initially set to 126 ^° C. in all cases. Then the pressure was gradually and slowly reduced to atmospheric pressure.

The best and simplest method used in the investigations consists in ^{directing the regenerated solution at an initial temperature of 126 °} C. to the bottom of a container which is preferably provided with packing and filled with liquid up to a height of 8 to 10 meters. The pressure of the rising liquid in the container decreases as the height of the liquid decreases, as a result of which a gradually increasing flow of vapor develops. The residence time of the solution in the expansion tank is controlled in such a way that the steam develops and acts on the solution in the same way and at the same time as it does

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- ίο- 'T951278

The reboiler corresponds to a conventional regeneration column. Other methods have been used for this purpose, e.g. as described in Italian patent application no. The best experimental results have been obtained when the CO _{2 is allowed} to flow off in the same amount as the steam extracts it from the solution (see FIG. 7). Other comparative tests were carried out for each solution and for each case, but the solution was simply and immediately extracted.

The results of the investigations are given in diagrams 1 to 5, each of which relates to a type of solution, the nature and composition of which is indicated in the diagram is. The abscissas give the carbon dioxide content of the solution at the beginning and the ordinates the carbon dioxide content am End again.

\ The initial temperature, C as mentioned above, set to 126 ^0th The final temperature, ie when the solution reaches atmospheric pressure in the upper part of the expansion vessel, is shown in the individual points of the curve.

In each diagram, the upper curve (dashed) represents the results that you get if you let the solution expand easily and immediately (normal flash); the lower curve (solid line) shows the results that are obtained when the solution is allowed to expand in the manner indicated above (controlled flash).

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For example (see diagram 1), a potassium arsenite solution with 200 g / liter K ₂ O and 140 g / liter As ₂ O, from the initial temperature 126 ⁰ C and a carbon dioxide content of 20 $> improves its carbon dioxide content with the simple and immediate expansion to atmospheric pressure 1ß, 5 #, where it cools to 100.5 ⁰ C, that the regeneration effect is practically vemachläesigbar. However, the solution is allowed to expand, the above mentioned manner, so the degree of regeneration £ improved corresponding to a CO ₂ content of only 3.5?, While at the same time cools to 104 ⁰ C.

• This result is of the utmost importance and of great practical importance, because the carbon dioxide content achieved of 3i5 ^ allows a cycle with a single cleaning step, whereas this carbon dioxide content is generally only obtained with a cycle with two cleaning steps, and because it is sufficient in one industrial plant regenerate the solution by supplying heat from the outside up to a carbon dioxide _{content of 20 JC su and then lower the CO 2} content to 3.5? t by letting the solution expand gradually to atmospheric pressure and increasing the heat content of the solution self-used. This makes it possible to reduce the heat supply from the outside to the reboiler of the regeneration column by about half *

The savings achieved in heat consumption according to the method of the invention can be seen in diagram 6, which relates to the Application of potassium arsenite solutions relates to the industrial

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be used on a large scale.

In diagram 6, the abscissa represents the percentage saving in heat supplyj the ordinate represents the carbon dioxide content of the solution before expansion, with the final carbon dioxide content after expansion at the various points of the Curve is indicated.

For example, a solution with an initial carbon dioxide content of 15 $> and an initial temperature of 126 ⁰ C, which is obtained from a regeneration column to which 21,500 Kcal / m of solution was fed, is allowed to expand to atmospheric pressure and has a carbon dioxide content of 2 ° (Point A of the diagram) · ';

This carbon dioxide content would have required a heat supply of 40 500 Kcal / m solution to the regeneration column. As a result, the heat supply is ^{reduced from 40,500 to 21,500 Kcal / m "5} solution, ie to $ 48 (point B), which is shown in the diagram by dashed lines.

Diagrams No. 2, 31 4 and 5 relate to other absorption solutions given in the diagram itself, i.e. Potassium carbonate solutions with various activators or Monoethanolamine solutions.

If one compares the results given in the diagrams, so it follows that the regeneration effect is a property that the alkali carbonate solutions receive when

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BAD ORfGiWAL

activating substances added. The regeneration effect is greatest when activated by the addition of AspCU Alkali carbonate solutions * She takes almost imperceptibly for 100 g / liter glycocollated solutions decreases, further decreases for 30 g / liter glycocollactivated solutions, and decreases even more for solutions activated with DEA and for .simple Carbonate solutions. Ethanolamine solutions also have a regenerative effect.

Ultimately, it turns out that the simple and sudden expansion does not produce a significant regenerative effect. The dashed lines that represent the * simple expansion, are not noticeably in front of the dotted lines, which indicate in the respective diagram "that the Löjnahm during the expansion no regeneration wiiicimg under-

- ^: s Another method of extracting the steam stream from its heating or boiling, regenerated solution consists of .ir.riii, the solution itself bio ?, \\ a subatmospheric pressure: "" ii o-'ipcin animals.

Tn. -Ta is the pail for a solution that comes in a ration of «· kol.i» ^? ine is regenerated, which works at a pressure, the dom atmos- »p-rii ^ Lsohtui pressure practically gLeiah iac =. Ώί & solution, i i. β tn üinrnn ο oak Pail eia «TaiuperaLnr between 105 ^ iJ I1S ° V, ana the Kegeaerabiontikolonrie is deducted uad in oiufii 'chamber or a Kaum aur Bipatißioa or Yerdaiaptuu ^

0 0 9 8 2 9/1 3 5 A

ORIGINAL BATHROOM

expanded, the negative pressure generated by means of a vacuum pump or other suitable mechanical device will. A jet pump is preferably used, into which the absorption column coming from the pressurized absorption column is used. Introduces spent solution and utilizes the energy it contains, as described in the Italian patent application No. 53,475.

Another method recommended in the present invention for generating negative pressure is to utilize the cleaning gases from ammonia or methanol synthesis in a jet pump, which are available under * a pressure of 100 to 300 atmospheres «

As stated in .ο! Ιεftshefid, the application of ½ "pre-pressure to the solution and the withdrawal of a steam stream from it requires no energy, \ iexm the steam itself in a zone of lower temperature and preferably in a zone in which the used, colder solution is available, which is. as a result arv / ar-rat, with condensation of the steam, is passed. More detailed information especially with regard to GO ^, and / or other acidic gases, which occur with steam, v / earth ± m following Puit. ^ T gemeiert ο

Likewise w! Ö in Pail · 1 were also hi.sr tint, raiicliimgen su Erläuceruiii'.B «» um! 7erg \ loiehr>3W8Oti'eii carried out, whereby never ■ known ?? ten and v / lchtigsfeeu subscription soldering v / eadet

ⁿ · BADORiGiNAL

0U0829 / 1354 ^B

It was found that the pressure reduction is the best Result achieved if it is carried out with the devices analogous to case 1 or in the manner and with the Devices listed in the Italian patent application Ur. 51 679 are described.

From work technical reasons, the initial temperature of the solution to 102 ⁰ C viird fixed and the Endt.emperatur very low applies at an appropriate negative pressure to about 80 to 85 ⁰ C ₅ which for simple or activated alkali metal carbonate, which are routed to the top of the absorber.

The results obtained in the investigations are those from Pail 1 completely analogous, with the exception that the regeneration effect is slightly lower, which can be attributed to it is that in this case the temperatures studied are lower, which lowers the replacement coefficient Kga.

For an explanation of the above, the results are shown in Diagram 13 reproduced based on a potassium arsenite solution refer «These results are similar to those in Diagram 1, but slightly lower.

In this case, too, as in the previous case 1, the regeneration effect for potassium arsenite solutions is greatest and decreases with the other, less activated solutions. Even less is it for simple GarbonatlÖsungen _t ^ ethanol amine solutions, however, have less in this case,

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BATH ORIGINAL

Regenerative effect than in the previous case 1 on what is due to the lower temperature at which the solution is treated. ,

3. Another method for withdrawing the steam stream the hot or boiling, regenerated solution consists in the fact that the solution itself treats with desorbing gases will. Of course, it is preferable to use gases that are chemically compatible with the solution and do not change or cause some chemical decomposition of the solution itself. The cleaning gases of the Ammonia or methanol synthesis, gas residues from fractionation • devices, heating gases if they are free of oxygen and .HgS are.

For this case study, for were "u Demonstrationsund performed comparison. There were previously in the" used * solutions known industrial technology, different absorption.

During the investigations, the solution had an initial temperature of 102 ^° C. This temperature was chosen for ease of use, as it is far away from the boiling point of the solution itself «. In industrial practice, however, the regenerated solutions generally have a temperature between 105 and 115 ^° C. and because of this, better results are obtained than those obtained in the investigations described here.

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The solution was fed to the top of a packed column while inerting in countercurrent to the bottom Gases (nitrogen) were introduced, their amount in the area was varied from 5 to 10 times the amount of solution.

However, it was found that the quantitative ratio of solution to inert gas of 1: 5 is best, especially if the steam extracted by the gas flow is used to heat the consumed Solution is used.

The inert gas was supplied at ambient temperature and the test conditions were set * so that the. Inert gas cooled the solution down to a temperature of 80 to 84 ^{° C.} For this purpose the solution flow was appropriately regulated in relation to the volume and the height of the column.

The tests were carried out for each type of solution and are shown in Diagrams 7 to 11 »

In these diagrams, the Absgjissen represent the initial carbon dioxide content of the _solutions? while the ordinates represent the carbon dioxide content reached at the end of the examination.

On the *: n iCurven of the vefschiodeueu Dlagranmie nind also ax. ΐοίη-ptär.'Uburtm der iVi-JUtigen rim Eolornienauulaeii aagegebeuo In eotex »f ^ öti Klannnorti Bind hucIl die ΓΘίΐΐρβΓΗΰΐΐΓύα Λ @ β rait H ₀ O uud Ου, ·,

U O 'vUU' '3 / Ί 3 Γ) Α

loaded inert gas at the outlet at the top of the column (i.e. the temperature of the dew point).

The results shown in the diagrams are the

results in case 1, controlled flash, - similar except for a slight decrease due to the fact that the exchange coefficient of the solutions decreases slightly as the Examination partitions lower compared to Pail 1

In this case one also finds that the regeneration effect caused by the flow of inert gases is greatest

for potassium arsenite solution and for the other solutions gradually abniaiEit => Also monoethanolamine (MEA) »solutions we is kit «has the same regulatory effect.

Other, supplementary investigations were carried out to determine how the carbon dioxide content of the solution changes when heat is withdrawn from the solution with an initial temperature of 102 ° G, ie when it cools down. These results are shown in Diagram 14 ivad XiQ'ZiHtii-Ai mxi Λΐδ use of a Kaliumara-Mitlösuiig, · Λ1β therefore ge ^ aliit v / urdo, v / ^ il it in the industry very viol · "/ im / ends i- / ird ₃

J.lii £ o) a ^ iiden werdea the veruehi ^ d raeti method of the invention T aiifj ^ efiihrfcj BrIJ ta la d ^ -rei? dor steam tiacli dem ->: .-. «t« ug off

dar lioiaaea or si & d.radeiij rsßönori €; rtan solution together with

OO a 8 2 9/1;) h U

COg and / or other acidic ones contained in the solution itself Gases is used to heat the used solution.

It seems important to point out two properties d) and e) that are specific to the two methods ϊ

d) The transition of the steam from one solution to the other happens spontaneously and does not require any energy consumption (theoretically it would even have to generate energy) until the regeneration solution has a temperature, or rather a steam pressure, that is greater than that of the consumed, absorbing the steam itself Solution is. It is known in the art and the skilled person will whether understand that this method is completely different is of your process in which the steam from the regenerated solution by means of a thermal compressor withdrawn and brought to sufficient pressure and temperature so that it for example on the Soil of a Regeneratiomslrolonne used i ^ erdon can. In this case energy is consumed, which is not the case with the method of the invention.

It should be noted, however, that the steam withdrawn from the regeneration solution, as already mentioned, contains a certain amount of OO ₂ and / or other acidic gases that change the physico-chemical process and, because of the transition from one solution to another, consume energy cause. It is, however, about: rather small amounts of energy, as stated at the end of the following section g).

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.20-

e) With tests carried out in a suitable manner, it was found that the amount of heat generated by the transition of the steam flow from the regenerated solution is released to the used solution, to a greater extent and better

is used in a way than it is with dem.in. the previous one Technology used heat exchanger happens. This is due to the fact that with equality of when heating temperatures reached, the used solution releases a larger amount of COp and / or other acidic gases and is therefore supplied in the regeneration column at conditions that are more favorable for its heat balance.

In fact, in the prior art, the heat exchanger heats the spent solution when it is still under the pressure at which it comes out of the absorption device. The solution is then expanded to the pressure of the regeneration device. It is known that the amount of heat consumed for this expansion is mainly used for the development of water vapor, which is a physically very rapid process, and to a lesser extent for the development of CO ₂ , which is regulated by chemical reactions that are known to take place slowly. The water vapor / carbon dioxide ratio is ultimately far above equilibrium.

However, using the heating method of the invention, it condenses the water vapor withdrawn from the regenerated solution on the used solution, which heats up, and the carbon dioxide is simultaneously

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urges. The final water vapor / carbon dioxide ratio is much closer to equilibrium. This brings with it a better utilization of heat, as by suitably carried out Investigations found:

These investigations consisted in the fact that the conditions of the process of the invention were reproduced, ie that a heating current of H ₂ O and COg in various ratios was brought into direct contact with a used solution, ie a solution with an increased carbon dioxide content. To make work easier, the investigations were carried out under atmospheric

spherical pressure carried out.

The results are shown in Diagram 12. The ordinate indicates the temperatures of the heating current and the abscissa & ä n content of carbon dioxide back to the solution reached after a certain time. The curves of the diagram relate! in each case on Kaliumai-senitlösungen with 200 g / liter ICJ O ₅ and ¹ IO g / liter ASgO ,, j on Kaliumcarbonatlösungeti with 250 g / liter KO and 50 g / liter Glykoteoll as an activator and a 2 5 m MSA solution . As is well known, the HoO / Cöp-Yerhaltetiis is determined by the L- :) temperature of the heating current, which the. Dew point rUM.'atöUt. Pur one Kaliuraarsetiifclöüimg sB gi'l t that a Heii / .a brom of a temperature of 90 ° 0 and ^ Ιϊι & ϊϊϊ 1I ₀ -O / (3Oq-Voί.νκίΐ tiiio you 2 _? 3 (PiKikt 1 -iaä iiiagramuis) di '"Lö-vuvig iua mi -ylVh'Mi · Kohlendi- ; jijrtgehal G from ϊί ■;' (l-uuh- :; 0 <iöe tn ^^ -.-. ^ Nuüui) reg ^ n ^ f: AVl ; Bo i.iirifcoeatioiiUugau νανΛβ Γ -: - ^ ΐ ^^ ΐ ^ ΐί:, -.-. N-; =: Λλκ Solution la j £ ifciii'i-r: v-höp.f-i3r v / ulae - H-; '·: {■ .-. ^ V ^ eSiUnν -ou iq;. · / .. · - f -Ή ---

BATH ORIGINAL

94 ⁰ C (point B of the diagram). "It is important to note here that repeated experimental investigations carried out for this purpose have shown that the stream of water vapor and CO _P raises the solution to a temperature that is above its own, heated. Probably this fact a saturated clean steam flow of 100 ⁰ G to those skilled only v / enig known. for example, any., boiling at 105 ⁰ G brine steam of 100 ⁰ G on what corresponds to the temperature of the pure solvent. heated a salt solution to 105 ⁰ G, ie a temperature above 100 ° ö.

In the above mentioned example of a Kaiiumarsenitiösung is noted that j in der'industriellen practice a regenerated arsenic! Tiösung of 110 ⁰ C, the spent solution to 100 to 102 ° (j warmed v / ill be monitored entering the Regenerafc OAU ^ -v. expanded into the upper part of the same,

cools down to approximately 94 ⁰ G, but only regenerates to a COg content of 44 to 48 f »instead of 29 #, as achieved in the example using the method of the invention»

f) You in the previous sections d) and e) aagesiollt- · .- »!! Overlays allow some for the user dung -! he Ί / ΰΓΒΰΙιΙβΊ-ίΛ ^ ίΐ Yorfatoeu of the invention advantageous (roundsät "A & 2.ü £ üuste.Ll? n>

As αώ -LiifBYig dft- : ''. I -.- i ^ '' .: Virihuü ^. y.taiigt vnn'de-, k? va cr ler re-

BAD ORIQtNAL

he part of the COp and / or other in the solution itself contained acidic gases (which is the main goal i used to with whom he comes into direct contact, to warm / warm and thus the omission of the previous one. Technology used heat exchanger enable.

Depending on the type of verwetideten solutions and of the working cycle in which they are used _for the two targets komien separately or together · reached are.

w 4

In many cases the extraction of the steam from the regenerated Solution has a remarkable 'regenerative effect' by removing significant amounts of COo and / or other acidic gases removed from the solution itself. This not only allows the amount of heat required to run the cycle to be considerable reduce, but also to purify the gas mixture in a single step, which is otherwise generally only after two. Steps is achieved. all of this

IT

has been explained above.

This can be seen in the case of strongly activated solutions, the typical representatives of which are arsenite solubilizing agents * or in the case of solutions which regenerates to a large extent in the regeneration column have been.

In contrast, significant amounts of COp were low

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and / or other desorbed acidic gases accompanying the steam lower the dew point of the heating medium and make it less suitable for heating the spent solution. In addition, the CO ₂ transition does not require that the steam pail does not occur.

the energy consumption.

The solutions of this kind are advantageously in the optimal or isothermal cycles where the heat exchanger is absent or unnecessary. Special .Examples of this application are in Examples 1, 3 and 6 given. With these it has proven to be expedient that the steam stream withdrawn from the regenerated solution is in suitable Cooling devices condensed or released to the outside.

Conversely, solutions with a low regeneration effect, in which the steam withdrawn from the regeneration solutions _{is accompanied by small amounts of CO 2} , have the best properties for heating the used solution and for partially or completely eliminating the heat exchanger. This is the case _for at non-activated solutions such as simple or carbonate solutions Äthanolaminlösungen and generally at solutions that have been regenerated in the Hegenerationsvorrichtung high degree. The solutions used especially for the absorption of HpS are most suitable for this case, since the HgS volume absorbed per volume of solution is in most cases small and therefore the vapor withdrawn from the regeneration solution is highly concentrated.

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The above-mentioned solutions are preferably used in conventional cycles and in the cycles in which there is a temperature difference between the absorption phase and the regeneration phase and in the cycles in which previously heat exchangers exist were used. ■

The cases in which both advantages described above are used at the same time are particularly advantageous. Examples of these cases are given in Examples 2, 4 and 5.

g) In the practical application of the invention, the steam withdrawn from the regenerated solution is brought into contact with the used solution by means of mixing devices (mixing or heating zone). This can be done in a single step, which is sufficient in the majority of cases, or in several successive steps if it is desired that the spent solution is heated to a temperature which almost approaches the temperature of the regenerated solution. This can be achieved with the device of Fig. 7 or with similar devices readily available to those skilled in the art. Xn. The device is shown in fig ο 7 'v / ird the steam entered in successive steps of the solution, while this rises in the ΚυΙοηη-3 on the right side of the figure "The eatzoijen in every single step" Steam becomes the used solution sugführfc, which au £. the aboorber comes in and in. the one on the left of the figure

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ORIGINAL BATHROOM

shown column in corresponding, consecutive Steps down.

If the used solution is used to generate negative pressure in a jet pump, see above how the jet pump works even the mixture of the steam with the solution (in eiaerii single Step or with multiple jet pumps). In many cases however, a simple jet pump is sufficient to achieve the required level desired effect ouch (see Fig. 2).

However, the regenerated solution becomes more inert with a stream

■ «

Treated gases, the heat transfer from the regenerated solution to the used solution is brought about by means of two zones y which generally consist of two ΙΌ "οιγϊι © ώ (M * 3 '- another corresponding device! the regenerated solution or the used solution pass through. Bar. The current of the inert gases goes sers'fc duroh the heating or evaporation sons passed through by the regenerated solution, νιο it is heated and humidified at the expense of the heat supplied by the solution, and then gets into the:? oa the used solution passed through Heis ™ or mixed soii.?. ü where the solution is heated / heated. The entrained steam troaae-izes aloh and smoldering. big becomes sine Yor · = regeneration of the · *? needed HlaaiKg itself; achieved, this i & ü in exercises Wigo 5 and in example 5 -aiage guides.

In the praicfcisohtm Anifenöung ä & r iii * i. Lndimg notes aian,

'dasa in the casesa 1 = and 2 «, _ä in ä & nen the steam means

0 0 9829 / 13S 4 'bath original

■ - 27 -

Negative pressure is withdrawn, the regenerated solution a lower one Pressure than the used solution. If you do not wish to use a jet pump in this case, it is necessary, to use mechanical drive means generally placed between the two columns, as shown in FIG Fig. 4 can be seen.

As stated above, the passage of the steam from one solution to the other does not consume any energy, while the passage of the CO ₂ accompanying the steam withdrawn from the regenerated solution consumes energy. However, the amount of this energy consumed is small.

In order to give the person skilled in the art a picture of the choice of the usual sizes, it should be noted that the energy consumption for the transition of the COo ^v o ¹¹ accompanying the steam to the regenerated solution cur consumed solution in the case of an alkaline arsenic, which is b "-I the expansion treatment with cooling from 1 ^ 6 ^Ü G to 104 ⁰ C and reducing the carbon dioxide di'elif? L.ts from 20 $ to 3 * 5?" regenerated, theoretically calculated as below 0.013 kilowatt hour χ 1000 calories, whereby a heating stream «M? i with a water vapor / carbon dioxide ratio of 5.4 is created.

For the, case of a 2.5 m monoethanolamine solution, which regenerates itself in the expansionary "nsbehandlung under cooling from 126 ⁰ C to 104 ⁰ C and with reduction of the Kohlendioxyögehalts of 20 to 15 # i" is the calculated power consumption

OO 9 8 2 9/1 3 5 h

8AD GrV--

0.0047 kilowatts q hour per 1000 calories moved from one solution to another.

h) It will be noted, finally, as already said several times hereinabove, that the withdrawal of the vapor stream _# cools the regenerated solution. As the person skilled in the art knows, this has the advantage that the solution is brought into the absorption column, the cooling device being wholly or partly omitted. · ■

i) The invention can of course also be applied to a multistage cycle. In Fig. 8, one application is the Invention shown in a two step cycle. The regenerated solutions of the first and second stage with a Stream of inert gases treated to improve their degree of regeneration.

The following examples illustrate the invention.

Example 1 ;

The following example shows a practical application of the explanations in section 1).

1 shows a system for COp removal from a gas of 28 atmospheres with an initial concentration of 18 $ COo. Here, with an alkaline arsenite solution of the composition 200 g / liter KgO and HO g / liter AspO,

washed.

OO 9 8 2 9/1 3 5 U _BATH

The used solution coming from the bottom of the absorber is brought to the top of the regeneration column R, which operates at 2 ATA, where it is regenerated to a carbon dioxide content of 20 $ , for which 21,000 Kcal / in solution are used.

*. The regenerated solution is drawn off at a temperature of 126 ^° C., which corresponds to the boiling temperature at the working pressure of the regeneration device, and then brought into the expansion column C, which is located in Pig. 1 to the left of the regeneration column R is located. This column is provided with trays or filled with packing material and filled up to a height of approx. 8 m from the solution itself. This rises up in the column and gradually develops steam in increasing quantities, which removes _{part of the GO 2 contained in the solution.}

Solution one Kohletidioxydgehalt of 3.5% at a temperature of 105 ⁰ O. - At the end of the expansion at the top of the column G ■-dl-e reached

The solution is oatnommen and at the head of Bxpansionskolonne means of the pump P brought to the absorption column A which, 70Ti faner subsequent cooling device with a single JH rom ode c in your split-stream according to the desired Röi- ti I Gunge grf ιd GEK TRJ 11 v / ir d.

Dio LUsun _t i then passes through the absorption column, aa its

009829 / 135A

Soil them with a carbon dioxide content of $ 66.5 - extracted and is returned directly to the regeneration column.

It is found that the solution in the regeneration column is regenerated up to a carbon dioxide content of 20 fo _m , v / ob with 21,000 Kcal / nr solution, while to obtain the solution with a carbon dioxide content of 3 * 5 #, as shown the expansion column G exits, a heat supply of 3? 400 Kcal / m would be necessary. Doh. the amount of heat is almost double.

In the example shown, the * s made the supply of heat to the reboiler by means of the gas v / ith which itself exiting the reboiler with siner Temperatur'von about 135 ⁰ C. It was found that the gas is suitably fed at the same temperature to the bottom of the absorber, where the solution is heated up to a temperature suitable for the heat balance of the regeneration device.

It is assumed that the solution is about 30% by volume / m of solution absorbed »Dar V / poor consumption is 700 Kcal / m absorbed COp.

One stellb sohlieaslich determines that contains part dos absorbed CO ₂ in the Expansionsk jlomiü-O-.im'u sagen® \ α \ ΐϊφί nnv., In üLnlgnn cases when the Crewinuimg · ds, the total GiS ₉ tiot nlohfc ^ eriöi ^ IBb ₁ kanu dar der E: cpai '»iiotiskoluntiö önt-Süg ^ ne Bafflpf can be derived directly into the Afemospiiärö what

0 09829/1354

with savings in the dimensions of the COn cooling device connected is.

The advantages shown in this example consist mainly in the fact that * a) the cleaning of the gas is carried out in a single step and the same degree of purification is achieved, for which a two-stage cycle would have been necessary according to the previously known technology} b) the supply of heat and as a result, the dimensions of the reboiler are only about half, whereby "the outflow of the hegeneration device are reducedj c) the CO ₂ -KUhIvorrich-

As stated above, processing can also be reduced if it is not necessary to _{recover all of the CO 9 absorbed}

ff. C ·

Example 2 and 3 :

Two examples are given below for the practical application according to the explanations in section 2).

The two examples relate to FIGS. 3 and 4. Both relate to the removal of carbon dioxide from a gas mixture with 18 i "carbon dioxide and a pressure of 2g ata by means of a Kaliuraarsenitlösung with 200 g / liter K ₀ O and 140 g / Litor ASPO ,. In both cases, the solution is ^{regenerated by supplying 26,400 Kcal / m 5 of} solution ir. Accordingly, a solution with a vird Kohlend ioxydgehalt $ 10> received. In both cases, the

009829/135 /. ·

BATH

treated regenerated solution from an initial temperature of 110 ⁰ C in the evaporation chamber Ό so that a vapor stream is withdrawn from it, which ^{corresponds to a cooling of the solution to about 85 0} C, whereby one improves the degree of regeneration of the solution to 2 i » (see Diagram 13). In practice, however, noticeably better values are often obtained.

In the cycle of the pig. 3 the vapor stream withdrawn in this way is passed outside without further utilization, while the solution exits from the evaporation chamber or evaporation zone C ^ and without further cooling (it has already ^{cooled to 85 0} C) is passed to the top of absorber A, where the gas mixture up to is purified to a COg content of 0.1 i ». When flowing through the absorber, the solution is heated by the heat of reaction and by the heat contained in the gas (the gas is introduced at 120 ^° C., which corresponds to the temperature at which it exits the reboiler) up to 98 ^° C. It reaches a Carbon dioxide content of $ 64> and is fed directly to the regeneration system. Corresponding to the change in the carbon dioxide content from 64 # to 2 $, the loading of the solution is 29.5 vol.CO ₂ / vol. Solution. The heat consumption is 895 Kcal / NnAjO ₂ .

In the cycle of FIG. 4, the vapor stream withdrawn from chamber C is ^{directed to chamber C 1} , where it is used to heat the used solution coming from the bottom of absorber A.

009829/135 U

will. As a result, the absorption temperatures are lowered, and the regenerated solution is cooled in the cooling device F at 58 ⁰ C and passed to the top of the absorber A, where it cleans the gas mixture up to a COG-content of 0.05 / 3 system. While flowing down in the absorber, the solution is heated to 80 ⁰ O by the heat of reaction and by the heat of the gas mixture introduced at a temperature of 120 G and reaches a carbon dioxide content of 73.5 $ Finally the solution is passed into chamber G ¹ , where it is heated by the stream of steam coming from chamber C-. It is then fed back to the regeneration device. According to a change in the carbon dioxide content of 73.5 i> 2 <fo beträgt'die loading the solution 34 Vol.COg / Vol.Lösung. The heat consumption is 770 Kcal / Nm ⁵ CO ₂ .

To withdraw the steam flow from the evaporation chambers with the letters Ml and M2 provided vacuum pumps, which generate a vacuum, which is applied to the from the evaporation chambers escaping steam is applied.

The advantages of the invention presented on the basis of the two above examples can be summarized as follows:

a) Reduction of the heat of regeneration. Regeneration heat for 1 m solution to a carbon dioxide content of 10 i "is 26 400kcal while until regeneration is at a carbon dioxide content of 2 # 40 500 Kcal.

00982 9/135 *

- jQ -

The invention allows the solution to au a carbon dioxide content of 2 fo with the. To regenerate the amount of heat that is required up to a carbon dioxide content of 10 fi. This saves H 100 Kcal / nr solution, ie approx. 35 $.

b) The one-step cycle is sufficient to achieve a GOp- ^ cleaning down to 0.05 to 0.1 #, the heat consumption being noticeably below 1000 Kcal / Nm CO ₂ . For this purpose, a two-stage cycle is required according to the previously known technology. This benefit is of course fundamental.

e) In example 3? that uses a conventional cycle with an absorption temperature that is well below the regeneration temperature, it is found that the heat exchanger between the regenerated solution and the 7erbra ^i! : .. jL v; r; Slogan no longer applies.

However, Example 2 uses an optimal cycle like. he was described at the beginning of the description *

Example 4 ?

This example explains the practical application using a jet pump.

This example corresponds to example 3 * ^ fis from FIG. 2 is, the jet pump I replaces the vacuum pump Mt and the mixing chamber CH of FIG. 4. It runs through the from the

.009829 / 1354 3AO ORIG

Used solution coming from the absorber the jet pump I, where it creates a negative pressure that came to the evaporation * - mer C works. From this a steam stream is withdrawn, the mixes in the jet pump itself and in the subsequent chamber in such a way that the solution is heated before it is introduced into the regeneration column. s

The rest of the functionality of the system is similar to that in Example 3

Examples 5 and 6 :

Two examples are given which relate to the case in which the steam flow by means of a flow from inert gases is withdrawn.

The two examples relate to FIG. 5 and both relate to the removal of carbon dioxide from a gas mixture with 21 $> CO ₂ and a pressure of 36 ata by means of a potassium arsenite solution with SOO g / liter K ₂ O and 140 g / liter ASpO. In both cases, the solution in the regenerator R is regenerated by adding 21,600 Kcal / m "" of solution. This corresponds to a regeneration wheel to a carbon dioxide content of 15 &

The liquid withdrawn from the bottom of the regeneration device is treated with a stream of inert gases with which it comes into direct contact in the evaporation chamber C. here

009829/135 h '

the solution is cooled to 85 ⁰ C and at a carbon dioxide content of 4 regenerieret i ". During this treatment it is found that the use of 4 m of inert gas * per rare solution is necessary. It is found that these quantities of inert gas are available in large quantities in cleaning steps in ammonia synthesis (cleaning steps that are carried out to prevent the accumulation of methane or other inert gases in the circulating gases of the synthesis plants).

In the cycle illustrated in FIG. 6, the solution that

regenerated after the treatment with the inert gas to a carbon dioxide content of 4 i ° and cooled to 85 ⁰ C 'is supplied directly and without further cooling of the absorption column A, where <?> is purified until a carbon dioxide content of 0.10 < . Then it runs down in the absorber and

i reaches at the end of the same through the heat of reaction and through 'the heat contained in the gas to be purified, which is ^{supplied at a temperature of 120 °} C., at which it emerges from the reboiler, a temperature of 98 ^° C. The solution of this Finally, the temperature is fed directly into the regeneration column, thus closing the cycle. The inert gases, however, are discharged to the outside in chamber C after direct contact with the used solution.

The reaching to the bottom of the absorber solution has a carbon dioxide content of 71 $ ", which corresponds to a loading solution of 32 VoI COP / Vol. The heat consumption is

009829 / 13S /.

675 Kcal / m ⁵

According to the cycle shown in Fig. 5, the inert gases, after direct contact with the regenerated solution in zone C, from which they exit heated and moistened, are passed into zone C, where they are used to heat the out., The bottom of the Absorber coming, used solution can be used. This makes it possible to advantageously lower the absorption temperatures. As a result, the regenerated solution is further from 85 ⁰ C to approx. 60 ⁰ C cooled and passed to the head of the absorber A, where it cleans the gas mixture to a carbon dioxide content of 0.05 #. Then runs. In the absorption column A down and heated by the heat of reaction and the heat of the gas mixture to 80 ⁰ C. Then it is passed into the zone C, where the current dervon C coming inert gases up to a temperature of about 94 ⁰ C heated, a certain amount

p removed and the solution bi & regenerated to a carbon dioxide content of 35 i>. Finally the solution is fed to the regeneration column.

In this example, the loading of the resulting solution is 37 Vol CO 2 / Vol solution. The heat consumption is 585 Kcal / m ⁵ CO ₂ -

The flow of inert gases, which _{has removed the CO 2} from the regenerated solution and possibly also from the used solution, is released into the atmosphere. This results in

■ 009829/135 *

. ₃ 8-ias-i278

a reduction in the amount of COg escaping from the regeneration system, which can be used for other purposes. In the first case, FIG. 6, the COp loss is a noticeable part of the total amount; in the second case, - Fig. _5f , it is only 16.5 #. '

As the expert knows, the first lall is the application of a conventional cycle in which in addition to improving the regenerative effect through the treatment of the regenerated solution by inert gases also the heat exchanger between the regenerated solution and the consumed

Solution no longer applies. However iia sweiten * case is present, the application of the optimum cycle in which susätslich to improve Regenerationswirlcung in the regenerated solutions also the advantage gegeb & I3T n. ₅ ^a nss the absorption temperatures in the range of 85 V ■ -.-: Cd vary ° ö and approach the optimum absorption temperature in an advantageous manner.

example 7 :

This example relates to the case of using a monoethanolamine solution. In a classic CO2 Rei.iiigangsanlage using the conventional cycle with a 2.5 molar Monoäthanolaminlösung the solution is fed to learning top of the stripper at a temperature of about ⁰ C and §6 occurs as * the bottom of the Eegenerationsvoirichtung with a carbon dioxide content of 0, 14 mol CO ₂ / ^Mo1 MS ^ ^and a temperature of 120 ⁰ C. Then the

ÖÖ9829 / 13S4

regenerated solution in counter-current in an exchange with the emerging from the absorber, "spent solution to a temperature of 96 ⁰ C, as stated above IGT.

The system will be modified and improved as follows:

a) The solution is in the regeneration column up to. a carbon dioxide content of 0.18 mol C0 ₂ / mol MEA regenerated with corresponding heat savings of the reboiler. The solution is then in an expansion chamber by means of

a negative pressure generated by a vacuum pump b 'treats and cooled to a temperature of about 100 C, wherein

is eliminated. The solution reaches a carbon dioxide content of 0.14 mol COg / mol MEA, which is the value of one after the classic Yurfahren working system corresponds.

The extracted by the vacuum pump vapor is brought into direct contact with the coming out of the absorbing solution, wherein it heats this up to about 96 ⁰ C. If the coming out of the absorbing solution having a temperature of about 85 ⁰ G, a single ErwärmunfTSsehritt and mixing step between the extracted steam and the spent solution is sufficient to completely whereby the heat exchanger accounts for Icrmn. However, if the solution coming from the absorber has a lower temperature, the exchanger can still be used partially or a multi-stage heating and steaming device can be used

009829/1354

- Use 40 as indicated in Fig. 7.

A particular simplification of the scheme can be achieved if the jet pump is used in such a way that the amount of heat in it the used solution is recycled. This allows The vacuum pump can be omitted, while the jet pump itself acts as a heating and mixing chamber.

Example 8 ;

• This example is based on the case of ^ S removal by 2 η diethanolamine solutions. '.

The system, which works according to the usual scheme, provides that the temperature at the top of the regeneration device is approximately 98 ^° C. and approximately 124 ^° C. at the bottom. The solution is withdrawn from the bottom of the regeneration device at said ■ temperature and has a content of about 0.12 mol HPS / Mol'Amin. In FIG. 4, the solution is passed into the expansion chamber C, where it is subjected to a stress relief, is achieved by suitable mechanical devices M2, and is cooled to a temperature of about 100 ⁰ C. Under these conditions, the vapor withdrawn from the solution is practically free of acid gases and is therefore used in the heating chamber C under the best conditions to heat the used solution coming from the absorber.

009629/1354

The spent solution passes at a temperature of 74 ⁰ C in the heating chamber ^f and O is heated to a temperature of 96 ⁰ C and then supplied to the head of the regeneration apparatus. The heating of the used solution from a temperature of approx. 40 ⁰ C, as it comes from the absorber, to a temperature of 74 ⁰ C takes place by means of a partial heat exchanger in which the solution with the regenerated solution coming from the expansion chamber C is in Contact is brought. In this way, the exchanger of the conventional cycle is partly omitted. If the total elimination of the exchanger is desired, the device in fig. 7 ·

This example is particularly suitable for the use of a jet pump, which is attached after the heating chamber C. will. In this, the heating of the solution causes only a slight development of acidic vapors, which the Do not excessively impair the efficiency of the jet pump.

009829/1354

Claims (1)

Claims ("Iy process for the elimination of GO ₂ and / or other acidic gases from gas mixtures by means of an absorption solution, which is brought into circulation between an absorption column in which the solution is in close and direct contact with the gas mixture for the purpose of cleaning the same and for removal is brought by GO ₂ and / or other acidic gases, and a regeneration column in which the solution is regenerated by secreting previously absorbed GO ₂ and / or other acidic gases by being brought to the boil by supplying external heat, characterized that the heat content of the hot and boiling, regenerated solution, which emerges from the regeneration kotoine, is used to withdraw a steam flow from the solution itself, whereby Jin. feil removes the GOp and / or the other acidic gases still present in the solution is, the so withdrawn vapor stream is passed into a zone of lower temperature and finally the cooled and g A large part of the regenerated solution is fed back into the absorption column, which closes the cycle. 2. The method according to claim 1, characterized in that the withdrawal of the steam stream from the regenerating lea solution is made by means of a pressure relief. 0 0 9 8 2 9 / I 3 S 4 ' BAD ORi _GiNAL ' 3 · Process according to claims 1 and 2, characterized in that that the withdrawal of the steam flow by one from one • under pressure working regeneration column coming solution is brought about, the solution itself from this overpressure is expanded to atmospheric pressure. 4 · The method according to claims 1 and 2, characterized in that the withdrawal of the steam stream from the regenerated Solution is accomplished by exerting a stress on the solution by means of mechanical devices will. 5. The method according to claim 1, characterized in that the Withdrawal of the steam flow from the regenerated solution is accomplished by a gas flow, which in narrow and direct Contact is made with the solution itself. 6 · Process according to claims 1 with 5 »characterized by that the vapor stream withdrawn from the regenerated solution in close and direct contact with the used, colder, solution coming from the absorption column is brought, the steam on the solution will koudensjort, the solution itself heated, part of the GOo contained in the solution and / or the other acidic gases are thereby eliminated and finally the so heated and partially regenerated, used solution is fed into the regeneration pool. 009829/1354 ORIGINAL BATHROOM 7 · Method according to claims 1, 2, 3, 4 and 6, thereby characterized in that the vapor stream of the regenerated solution is withdrawn in successive steps? and the steam extracted from each step of the consumed Solution is supplied, which comes from the absorber in the same, corresponding, successive steps. 8. The method according to claims 1 to 5, characterized in-JP - net that the steam withdrawn from the regenerated solution in a cooling device is condensed. 9. The method according to claims 1 to 5, characterized in that the steam withdrawn from the regenerated solution is _{discharged to the surrounding atmosphere together with the CO 2} and / or the other eliminated -Jases. ORIGINAL IMSPECTED 009829/13 54