CA1124487A - Process for selective removal of cyclic urea from hindered amine gas treating solution - Google Patents
Process for selective removal of cyclic urea from hindered amine gas treating solutionInfo
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- CA1124487A CA1124487A CA342,448A CA342448A CA1124487A CA 1124487 A CA1124487 A CA 1124487A CA 342448 A CA342448 A CA 342448A CA 1124487 A CA1124487 A CA 1124487A
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- Prior art keywords
- cyclic urea
- solution
- acid gas
- filter
- hindered amine
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1412—Controlling the absorption process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1425—Regeneration of liquid absorbents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
Abstract
U.S. 972,500 ABSTRACT OF THE DISCLOSURE
In the process of the present invention, a cyclic urea degradation product formed as a by-product of a hindered amine acid gas scrubbing process is removed from a circulating amine scrubbing solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.
In the process of the present invention, a cyclic urea degradation product formed as a by-product of a hindered amine acid gas scrubbing process is removed from a circulating amine scrubbing solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.
Description
4~37
2 FIELD OF THE INVENTION
3 This invention relates to a process for the removal
4 of a cyclic urea reaction product in an amine gas treating process which involves an absorption and a regeneration sys-6 tem. More particularly, the invention is concerned with the 7 selective precipitation and filtration of a cyclic urea 8 degradation product which forms as a by-product in the feed 9 gas scrubbing process.
DESCRIPTION OF THE PRIOR ART
11 It is well known in the art to treat gases and 12 liquids, such as mixtures containing acidic gases including 13 CO2, H2S, SO2, SO3, CS2, HCN, COS and oxygen and sulfur 14 derivatives of Cl - C4 hydrocarbons with amine solutions to remove these acidic gases. The amine usually contacts the 16 acidic gases and liquids as an aqueous solution containing 17 the amine in an absorber tower with the aqueous amine solution 18 contacting the acidic fluid countercurrently.
19 The acidic scrubbing processes known in the art can be generally classified into three (3) categories.
21 The first category is generally referred to as the 22 aqueous amine process where relatively large amounts of amine 23 solution are employed during the absorption. This type of 24 process is often utilized in the manufacture of H2 for ammonia production where nearly complete removal of the acid gas, such 26 as CO2 is required. It is also used in those instances where 27 an acid gas, such as CO2 occurs with other acid gases or 28 where the partial pressure of the CO2 and other gases are low.
7' 1 The second category is generally referred to as the 2 aqueous base scrubbing process or "hot potash" process. In 3 this type of process a small level of an amine is included as 4 an activator for the aqueous base used in the scrubbing solu-tion. This type of process is generally used where bulk 6 removal of an acid gas, such as CO2 is desired. This process 7 also applies to situations where the CO2 and feed gas pres-8 sures are high. In such processes, useful results are 9 achieved using aqueous potassium carbonate solutions as amine activators.
11 A third category is generally referred to as the 12 non-aqueous solvents process. In this process, water is a 13 minor constituent of the scrubbing solution and the amine is 14 dissolved in the liquid phase containing the solvent. In this process up to 50% of amine is dissolved in the liquid 16 phase. This type of process is utilized for specialized 17 applications where the partial pressure of CO2 is extremely 18 high and/or where many acid gases are present, e.g., COS, 19 CH3SH, and CS2.
The present invention relates to a process for the 21 selective separation of a cyclic urea degradation product 22 which may form as a by-product of the practice of the second 23 category of acid scrubbing process described above, namely, 24 the aqueous base scrubbing process or "hot potash" process in which a hindered amine is used.
26 Many industrial processes for removal of acid gases, 27 such as CO2, use regenerable aqueous alkali scrubbing solu-28 tions, such as an amine and potassium carbonate which are 29 continuously circulated between an absorption zone where acid gases are absorbed and a regeneration zone where they 31 are desorbed, usually by steam-stripping. The capital~ cost 32 of these acid scrubbing processes is generally controlled by 33 the size of the absorption and regeneration towers, the size 34 of the reboilers for generating stripping steam, and the size of the condensers, which condense spent stripping steam so 36 that condensate may be returned to the system to maintain 37 proper water balance. The cost of operating such scrubbing `~ 4~37 l plants is generally related to the amount of heat required 2 for the removal of a glven amount of acid gas, e.g., thermal 3 efficiency, sometimes expressed as cubic feet of acid gas 4 removed per pound of steam consumed. Means for reducing the `~ 5 costs in operating these industrial processes have focused 6 on the use of absorbing systems or combinations of chemical 7 absorbants which will operate more efficiently and effectively 8 in acid gas scrubbing processes using existing equipment.
9 It is disclosed in U.S. Patent Nos. 4,112,050;
4,112,051 and 4,112,052 that sterically hindered amines 11 unexpectedly improve the efficiency, effectiveness and cyclic 12 working capacity of the acid gas scrubbing processes in all 13 three of the above-mentioned process categories. In the 14 case of the sterically hindered amine activated "hot potash"
lS CO2 containing acid gas scrubbing process of the invention 16 described in U.S. Patent No. 4,112,050, the process can be 17 operated at a cyclic working capacity significantly greater 18 than when diethanolamine or 1,6-hexanediamine is the amine 19 activator used in a similar process. It is postulated that the increase in cyclic capacity observed with the sterically 21 hindered amines is due to the instability of their carbamates.
22 In that respect, sterically hindered amines are similar to 23 tertiary amines. Tertiary amines are not used on a commer-24 cial scale for carbon dioxide containing acid gas scrubbing due to their low rates of absorption and desorption.
26 N-alkyl alkylene diamines are advantageously used 27 as sterically hindered amine activators in the "hot pot"
28 process. A preferred sterically hindered amine used as an 29 activator in the "hot pot" process is N-cyclohexyl-1,3-propanediamine. This amine in the presence of an amino acid 31 is sufficiently water soluble under absorption and desorption 32 conditions to maintain a single phase and it also has a very ; 33 high absorption capacity.
34 Although N-cyclohexyl-1,3-propane diamine has been found to produce excellent results as an activator in the "hot 36 pot" treating process, one drawback in processes where it has 'B7 1 been used is that it produces a cyclic urea product when the 2 acid treated gas is rich with CO2 and also contains H2S. The ` 3 cyclic urea has a deleterious effect on CO2 removal rates and 4 must be removed and replaced with fresh N-cyclohexyl-1,3-propanediamine. The makeup rate for the hindered amine has ; 6 a minimal effect on the process economics; however, the cyclic 7 urea that is formed must be selectively removed in order to 8 be able to maintain acid gas removal performance.
9 The invention which is disclosed herein represents an improvement to the "hot pot" amine activated gas treating 11 process which includes the use of a hindered amine having a 12 tendency to form cyclic ureas under CO2 rich conditions in 13 the presence of H2S. This invention discloses a processing step 14 wherein the cyclic urea can be selectively removed from the circulating solution thereby preventing any loss in acid gas 16 removal capabilities.
18 An acid gas scrubbing process providing for the 19 selective separation of a cyclic urea reaction product which forms as a by-product during the acid gas removal, said pro-21 cess comprising:
22 (a) contacting an acid gas mixture with an aqueous 23 solution, preferably in countercurrent flow, in an absorption 24 zone, said aqueous solution comprising an alkaline material comprised of a basic alkali salt or metal hydroxide selected 26 from the group consisting of alkali metal bicarbonates, carbon-27 ates, hydroxides, borates, phosphates and their mixtures, and 28 an activator for said basic salt comprising at least one 29 sterically hindered amine having the generic formula:
R-NH-(CH2)~-NH2 31 where R is a secondary or tertiary alkyl or cycloalkyl hydro-32 carbon having 4-20 carbon atoms and m is 2-5, at elevated 33 temperatures and pressures such that a cyclic urea degrada-34 tion product having the generic formula:
~.Z44~37 (CH ) f H2 I H2 R - N-____ / NH
where R is a secondary or tertiary alkyl or cycloalkyl having 4-20 carbon atoms and m is 0-3; is formed and a preferred loading of about 1 to about 10 SCF of acid gas per gallon of said aqueous solution is achieved;
(b) passing the acid gas rich aqueous solution produced from said step (a) to a regeneration zone preferably operated at temperatures ranging from about 200F to about 250F and pressures ranging from about 1 psig to about 15 psig where it is contacted, preferably in countercurrent flow, with steam to strip the acid gas impurities therefrom;
(c) cooling a portion of the lean solution exiting from said regeneration zone to temperatures ranging from about 80-180F
such that said cyclic urea degradation product is selectively precipitated from said lean solution;
(d) passing said lean solution containing said precipi-tated cyclic urea degradation product to a separation zone to remove at least a portion of said cyc~ic urea degradation product from said lean solution.
In a preferred mode of operation, the invention comprises the additional steps of:
; (e) monitoring the accumulation of said degradation product in said separation zone, preferably a filter medium, until the pressure drop across said filter medium reaches about 25 psi , ~L~.24487 at which time said filter is segregated and a clean filter is substituted therefor;
: (f) the segregated filter is cleaned by washing with hot water having a preferred temperature from about 200-240F.
The degradation product forms primarily at rich condi-tions and gradually builds up in the solution causing a drop-off in acid gas removal capabilities for the circulat-~' .
-~'`
.
-5a-` B~
-.. - ~ .
1 ing solution. When there is a buildup, it becomes necessary 2 to remove the cyclic urea degradation product so as to main-3 tain the enhanced acid gas removal rate for the hindered 4 amine solution. This is accomplished in the process of the present invention by providing a slip stream from the lean 6 solution which is cooled to a preferred temperature of 130~-7 160F and then passed over a bed of carbon or a filter medium.
8 The cyclic urea material was found to have unanti-9 cipated solubility properties when present in the circulating solution which contains X2CO3, KHCO3, KHS, the sterically 11 hindered amine and amino acid. The cyclic urea which has 12 certain physical properties similar to those of the hindered 13 amine was found unexpectedly to selectively come out of the 14 solution as it was cooled from 200F to a temoerature of about 180-80F. The desired specific temperature may be chosen on 16 the basis of the concentration of K2CO3 in the solution. In 17 this connection a typical temperature operating range for 18 various K2CO3 concentrations is given in Figure 2 described 19 hereinafter-For a scrubbing solution comprising about 30 wt.~
21 K2CO3 and cooled to 160- 130F little or none of the other 22 components come out of the solution. If this 30 wt.~ K2CO3 23 solution is cooled to 100~F and below, then KHC03 will also 24 precipitate from the solution and the process will no longer be selective. Similarlv, for a solution comprising 25 wt.~
26 K2CO3 and cooled to a temperature between 80 and 140F only 27 cyclic urea is precipitated from the solution.
28 The invention disclosed herein describes the temper-29 ature region in which the cyclic urea can be selectively precipitated and removed without removing any of the other 31 many components in the solution.
33 Figure 1 is a schematic flow diagram of one embodi-34 ment of the claimed invention.
Figure 2 is a plot of the typical operating region 36 in which cyclic urea can be selectively precipitated as a ~.Z~4~7 ,, 1 function of wt.% K2CO3 in a solution and the solution temper-2 ature.
4 The acidic components which will be removed from the gaseous mixture by the scrubbing process will preferably 6 be selected from the group consisting of CO2 alone or in . .~
7 combination with H2S, SO2, CS2, HCN, COS and the oxygen and 8 sulfur derivatives of Cl_C4 hydrocarbons.
9 The alkaline material comprising basic alkali salts or metal hydroxides will be selected from the group consist-11 ing of alkali metal bicarbonates, carbonates, hydroxides, 12 borates, phosphates and their mixtures.
13 The contacting of the absorbent mixture and the acid 14 gas may take place in any suitable contacting tower. In such processes, the gaseous mixture from which the acid gases are 16 to be removed may be brought into intimate contact with the 17 absorbing solution using conventional control means such as 18 a tower packed with, for example, ceramic rings or with bub-19 ble capped plates or sieve plates or a bubble reactor. In a preferred mode of practicing the invention, the absorption 21 step is conducted by feeding the gaseous mixture into the 22 base of the tower while the lean absorbing solution is fed 23 into the top. The gaseous mixture, free largely from acid 24 gases, emerges from the top. Preferably, the temperature of the absorbing solution during the absorption step is in 26 the range from about lS0F to about 270F and more preferably 27 from 150F to about 250F. Pressures may vary widely, accept-28 able pressures being between 5 and 2000 psig. In the desor-29 ber, the pressures will range from about 1 to 15 psig. The process can be better understood by reference to the follow-31 ing detailed description.
32 Referring to the figure, sour gas is introduced via 33 line 1 into ahsorption column 2 where it is contacted with 34 the aqueous scrubbing solution introduced via line 22. The scrubbing solution is at a temperature of about 200F and has 36 an amine concentration of from 1 to 10 wt.~, preferably 3 to ~L~.2~37 1 8 wt.~. As the absorbent li~uid passes down the absorber 2 column, acid gas impurities are absorbed.
3 The absorbent solution, enriched with acid gas im-4 purities, passes out of absorber column 2 into line 3 which passes the enriched solution through heat exchanger 4 into 6 line 5. Line 5 passes the enriched solution into the regen-7 erator 6 where the acid gases are stripped from the solution 8 and pass overhead through line 11. The lean solution formed 9 in the regenerator column passes to the bottom of column 6 and out via line 7 which feeds the lean solution to reboiler 11 8 where it is boiled by steam entering via line 9, the acid 12 vapors being passed via line 10 to the regenerator 6. The 13 lean ~essentially acid free) solution passes out of reboiler 14 8 via line 12. Line 12 passes the lean solution through pump 13 into line 14. Line 14 passes the lean solution into 16 heat exchanger 4 and some of the solution is cooled further 17 in heat exchanger 19 with cooling water entering via line 18 18 down to cool the solution to the temperature range in which 19 substantially only cyclic urea is precipitated. As used herein, the term "precipitate" is defined as particles which 21 are separated from the solution irrespective of whether the 22 particles would settle to the bottom of the solution or float 23 on top. In this process the cyclic urea removed from the 24 solution is less dense than the solution and hence will float on the surface. For a solution comprising about 30 wt.~
26 K2CO3 the solution should be preferably cooled to 180F to 27 120F, as indicated in Figure 2, more preferably to 160 28 to 130F, most preferably 150 to 135F to selectively pre-29 cipitate the cyclic urea degradation product while keeping all other components in the solution. Similarly, as shown in 31 Figure 2, a 25 wt.~ K2CO3 solution should be cooled to a 32 temperature ranging between 80F and 140F, preferably 90-33 120F, to selectivelv precipitate only the cyclic urea.
34 Maximum cooling effect for typical K2CO3 concentrations may be obtained by operation at a temperature in the range of 36 between 120F-80F. The solution containing the cyclic urea ~.2~37 g 1 solids is passed into line 15 which passes it to filter ele-2 ment 16. The cyclic urea degradation product accumulates on 3 the filter and is thereby selectively removed from the lean 4 solution. When the ultimate buildup of the insoluble mater-ial on the filter causes a pressure drop of, for example, 6 about 25 psi, a secondary filter 17 is cut in to allow con-7 tinued operation of the process during the cleaning of the 8 segregated filter.
9 The lean solution passes out of filter 16 via line 23 and joins with some of the other lean solution in line 21 11 which was not cooled by exchanger 19. These two streams 12 combine and enter the top of the absorber. The purified 13 gas passes out of absorber 2 via line 24. Hot water having 14 a temperature of about 230F is passed via line 20 into filter element 16 in order to wash the cyclic urea from the 16 filter and to permit its effective reuse.
18 The following is a summary of several examples 19 which describe the invention.
21 A gas treating solution was prepared which had the 22 following composition: 30 wt.% K2CO3 (with 10% as KHC03).
23 6.0 wt.% cyclohexyl-1,3-propane diamine, 6.1 wt.% pipecolinic 24 acid, 56.2 wt.% water, and 1.7 wt.% cyclic urea, i.e., 25 1-cyclohexyl-hexahydro-2-pyrimidinone. The solution at 200F
26 was present as a single liquid phase. This solution was then 27 cooled at 150F and was passed over a filter element which 28 was a cotton wound element having a nominal 100~ size. The 29 cyclic urea content was decreased from 1.7 wt.% to less than 1.0 wt.~. The filtration rate was 0.5 gpm and the filter 31 size was a 3" diameter cylinder, 4" high with an inner opening 32 of about 1" diameter. The filter cake was analyzed to be 33 pure cyclic urea with none of the other solution components 34 present. This example shows that the cyclic urea can be selectively removed by this process. It is not necessary to 36 completely remove all the cyclic urea but just to be able :, ` 1 to keep the concentration at a nomimally low level even though 2 it is constantly being produced within the process.
4 The gas treating solution described in Example 1 was cooled to 130F at which point considerably more cyclic 6 urea came out of the solution. Operation of the process at ~; 7 these conditions, however, produced a somewhat inoperable 8 condition due to the plugging tendency of the resulting pre-9 cipitate. In the flowing system in which the stream is being continuously filtered such a line plugging tendency as 11 observed above made the system somewhat inoperable. Therefore, 12 this test indicated that for this solution cooling to below 13 130F leads to an undesired operability problem. The solids 14 which were filtered during the test were again found to be pure cyclic urea with none of the other components of the 16 solution present.
17 EXAMæLE 3 .
18 Another gas treating solution was prepared that was 19 similar to that shown in Example 1 but which had about 30~ of the K2CO3 present as KHC03. In this solution, cooling from 21 200F to 150F again caused the cyclic urea to selectively 22 precipitate from the solution. As the solution was further 23 cooled to somewhat below 100F, it was found that the pro-24 cess was no longer selective in that in addition to the cyclic urea precipitating out, KHC03 was also precipitated 26 out. This test further shows the critical temperature range 27 over which the cyclic urea selectively precipitates. If the 28 temperature goes below about 100F, the process is no longer 29 selective. The filter cake in this test was found to contain substantial amounts of KHCO3.
32 Another gas treating solution was prepared which 33 had a composition similar to that shown in Example 1 except 34 that the cyclic urea content was 1.4 wt.~o. This solution was cooled to 148F and was filtered using a filter arrange-36 ment as described in Example 1 but with a 5~ element rather ~ 2~7 1 than the 100~ element. The run was carried out at 0.5 gpm 2 and the filter cake collected was analyzed and was found to 3 be pure cyclic urea. In this test, the run was carried out 4 until the pressure drop across the element reached about 25 psi.
7 After completion of the run described in Example 4 8 the filter had a pressure drop of 25 psi due to the cyclic 9 urea cake on the filter element. This cake was washed with 170F water and a second cycle was attempted in which case 11 a run of only about 25% as long as the initial run occurred.
12 This indicated that the washing with 170F water was not an 13 effective cleaning process. The filter was then washed with 14 230F water and then another cycle was attempted. In this case, the cycle length was equivalent to that of the initial 16 cycle on the fresh filter. Three more complete cycles were 17 run in which the filter cake was washed with 230F water 18 after a 25 psi pressure drop had built up due to the accumu-19 lation of the cyclic urea cake. In each case the amount of cyclic urea removed was the same as that with a new filter.
21 These tests indicated an effective washing techni~ue in which 22 the water temperature criticality was demonstrated.
24 Another gas treating solution was prepared compris-ing: 25 wt.~ K2CO3 (with 20% of this present as KHCO3), 6.3 26 wt.% cyclohexyl-1,3-propane diamine, 3 wt.~ pipecolinic acid, 27 0.8 wt.% cyclic urea and the balance water. The solution was 28 then cooled to about 85F. The filter cake was collected, 29 analyzed, and found to be substantially pure cyclic urea.
Although the subject process has been described with 31 reference to a specific embodiment, it will be understood that 32 it is capable of further modification. Any variations, uses 33 or adaptations of the invention following, in general, the 34 principles of the invention are intended to be covered, including such departures from the present disclosure as come 36 within known or customary practice in the art to which the ~,~ Z~7 1 invention pertains and as may be applied to the essential 2 features hereinbefore set forth, and as fall within the scope 3 of the invention.
DESCRIPTION OF THE PRIOR ART
11 It is well known in the art to treat gases and 12 liquids, such as mixtures containing acidic gases including 13 CO2, H2S, SO2, SO3, CS2, HCN, COS and oxygen and sulfur 14 derivatives of Cl - C4 hydrocarbons with amine solutions to remove these acidic gases. The amine usually contacts the 16 acidic gases and liquids as an aqueous solution containing 17 the amine in an absorber tower with the aqueous amine solution 18 contacting the acidic fluid countercurrently.
19 The acidic scrubbing processes known in the art can be generally classified into three (3) categories.
21 The first category is generally referred to as the 22 aqueous amine process where relatively large amounts of amine 23 solution are employed during the absorption. This type of 24 process is often utilized in the manufacture of H2 for ammonia production where nearly complete removal of the acid gas, such 26 as CO2 is required. It is also used in those instances where 27 an acid gas, such as CO2 occurs with other acid gases or 28 where the partial pressure of the CO2 and other gases are low.
7' 1 The second category is generally referred to as the 2 aqueous base scrubbing process or "hot potash" process. In 3 this type of process a small level of an amine is included as 4 an activator for the aqueous base used in the scrubbing solu-tion. This type of process is generally used where bulk 6 removal of an acid gas, such as CO2 is desired. This process 7 also applies to situations where the CO2 and feed gas pres-8 sures are high. In such processes, useful results are 9 achieved using aqueous potassium carbonate solutions as amine activators.
11 A third category is generally referred to as the 12 non-aqueous solvents process. In this process, water is a 13 minor constituent of the scrubbing solution and the amine is 14 dissolved in the liquid phase containing the solvent. In this process up to 50% of amine is dissolved in the liquid 16 phase. This type of process is utilized for specialized 17 applications where the partial pressure of CO2 is extremely 18 high and/or where many acid gases are present, e.g., COS, 19 CH3SH, and CS2.
The present invention relates to a process for the 21 selective separation of a cyclic urea degradation product 22 which may form as a by-product of the practice of the second 23 category of acid scrubbing process described above, namely, 24 the aqueous base scrubbing process or "hot potash" process in which a hindered amine is used.
26 Many industrial processes for removal of acid gases, 27 such as CO2, use regenerable aqueous alkali scrubbing solu-28 tions, such as an amine and potassium carbonate which are 29 continuously circulated between an absorption zone where acid gases are absorbed and a regeneration zone where they 31 are desorbed, usually by steam-stripping. The capital~ cost 32 of these acid scrubbing processes is generally controlled by 33 the size of the absorption and regeneration towers, the size 34 of the reboilers for generating stripping steam, and the size of the condensers, which condense spent stripping steam so 36 that condensate may be returned to the system to maintain 37 proper water balance. The cost of operating such scrubbing `~ 4~37 l plants is generally related to the amount of heat required 2 for the removal of a glven amount of acid gas, e.g., thermal 3 efficiency, sometimes expressed as cubic feet of acid gas 4 removed per pound of steam consumed. Means for reducing the `~ 5 costs in operating these industrial processes have focused 6 on the use of absorbing systems or combinations of chemical 7 absorbants which will operate more efficiently and effectively 8 in acid gas scrubbing processes using existing equipment.
9 It is disclosed in U.S. Patent Nos. 4,112,050;
4,112,051 and 4,112,052 that sterically hindered amines 11 unexpectedly improve the efficiency, effectiveness and cyclic 12 working capacity of the acid gas scrubbing processes in all 13 three of the above-mentioned process categories. In the 14 case of the sterically hindered amine activated "hot potash"
lS CO2 containing acid gas scrubbing process of the invention 16 described in U.S. Patent No. 4,112,050, the process can be 17 operated at a cyclic working capacity significantly greater 18 than when diethanolamine or 1,6-hexanediamine is the amine 19 activator used in a similar process. It is postulated that the increase in cyclic capacity observed with the sterically 21 hindered amines is due to the instability of their carbamates.
22 In that respect, sterically hindered amines are similar to 23 tertiary amines. Tertiary amines are not used on a commer-24 cial scale for carbon dioxide containing acid gas scrubbing due to their low rates of absorption and desorption.
26 N-alkyl alkylene diamines are advantageously used 27 as sterically hindered amine activators in the "hot pot"
28 process. A preferred sterically hindered amine used as an 29 activator in the "hot pot" process is N-cyclohexyl-1,3-propanediamine. This amine in the presence of an amino acid 31 is sufficiently water soluble under absorption and desorption 32 conditions to maintain a single phase and it also has a very ; 33 high absorption capacity.
34 Although N-cyclohexyl-1,3-propane diamine has been found to produce excellent results as an activator in the "hot 36 pot" treating process, one drawback in processes where it has 'B7 1 been used is that it produces a cyclic urea product when the 2 acid treated gas is rich with CO2 and also contains H2S. The ` 3 cyclic urea has a deleterious effect on CO2 removal rates and 4 must be removed and replaced with fresh N-cyclohexyl-1,3-propanediamine. The makeup rate for the hindered amine has ; 6 a minimal effect on the process economics; however, the cyclic 7 urea that is formed must be selectively removed in order to 8 be able to maintain acid gas removal performance.
9 The invention which is disclosed herein represents an improvement to the "hot pot" amine activated gas treating 11 process which includes the use of a hindered amine having a 12 tendency to form cyclic ureas under CO2 rich conditions in 13 the presence of H2S. This invention discloses a processing step 14 wherein the cyclic urea can be selectively removed from the circulating solution thereby preventing any loss in acid gas 16 removal capabilities.
18 An acid gas scrubbing process providing for the 19 selective separation of a cyclic urea reaction product which forms as a by-product during the acid gas removal, said pro-21 cess comprising:
22 (a) contacting an acid gas mixture with an aqueous 23 solution, preferably in countercurrent flow, in an absorption 24 zone, said aqueous solution comprising an alkaline material comprised of a basic alkali salt or metal hydroxide selected 26 from the group consisting of alkali metal bicarbonates, carbon-27 ates, hydroxides, borates, phosphates and their mixtures, and 28 an activator for said basic salt comprising at least one 29 sterically hindered amine having the generic formula:
R-NH-(CH2)~-NH2 31 where R is a secondary or tertiary alkyl or cycloalkyl hydro-32 carbon having 4-20 carbon atoms and m is 2-5, at elevated 33 temperatures and pressures such that a cyclic urea degrada-34 tion product having the generic formula:
~.Z44~37 (CH ) f H2 I H2 R - N-____ / NH
where R is a secondary or tertiary alkyl or cycloalkyl having 4-20 carbon atoms and m is 0-3; is formed and a preferred loading of about 1 to about 10 SCF of acid gas per gallon of said aqueous solution is achieved;
(b) passing the acid gas rich aqueous solution produced from said step (a) to a regeneration zone preferably operated at temperatures ranging from about 200F to about 250F and pressures ranging from about 1 psig to about 15 psig where it is contacted, preferably in countercurrent flow, with steam to strip the acid gas impurities therefrom;
(c) cooling a portion of the lean solution exiting from said regeneration zone to temperatures ranging from about 80-180F
such that said cyclic urea degradation product is selectively precipitated from said lean solution;
(d) passing said lean solution containing said precipi-tated cyclic urea degradation product to a separation zone to remove at least a portion of said cyc~ic urea degradation product from said lean solution.
In a preferred mode of operation, the invention comprises the additional steps of:
; (e) monitoring the accumulation of said degradation product in said separation zone, preferably a filter medium, until the pressure drop across said filter medium reaches about 25 psi , ~L~.24487 at which time said filter is segregated and a clean filter is substituted therefor;
: (f) the segregated filter is cleaned by washing with hot water having a preferred temperature from about 200-240F.
The degradation product forms primarily at rich condi-tions and gradually builds up in the solution causing a drop-off in acid gas removal capabilities for the circulat-~' .
-~'`
.
-5a-` B~
-.. - ~ .
1 ing solution. When there is a buildup, it becomes necessary 2 to remove the cyclic urea degradation product so as to main-3 tain the enhanced acid gas removal rate for the hindered 4 amine solution. This is accomplished in the process of the present invention by providing a slip stream from the lean 6 solution which is cooled to a preferred temperature of 130~-7 160F and then passed over a bed of carbon or a filter medium.
8 The cyclic urea material was found to have unanti-9 cipated solubility properties when present in the circulating solution which contains X2CO3, KHCO3, KHS, the sterically 11 hindered amine and amino acid. The cyclic urea which has 12 certain physical properties similar to those of the hindered 13 amine was found unexpectedly to selectively come out of the 14 solution as it was cooled from 200F to a temoerature of about 180-80F. The desired specific temperature may be chosen on 16 the basis of the concentration of K2CO3 in the solution. In 17 this connection a typical temperature operating range for 18 various K2CO3 concentrations is given in Figure 2 described 19 hereinafter-For a scrubbing solution comprising about 30 wt.~
21 K2CO3 and cooled to 160- 130F little or none of the other 22 components come out of the solution. If this 30 wt.~ K2CO3 23 solution is cooled to 100~F and below, then KHC03 will also 24 precipitate from the solution and the process will no longer be selective. Similarlv, for a solution comprising 25 wt.~
26 K2CO3 and cooled to a temperature between 80 and 140F only 27 cyclic urea is precipitated from the solution.
28 The invention disclosed herein describes the temper-29 ature region in which the cyclic urea can be selectively precipitated and removed without removing any of the other 31 many components in the solution.
33 Figure 1 is a schematic flow diagram of one embodi-34 ment of the claimed invention.
Figure 2 is a plot of the typical operating region 36 in which cyclic urea can be selectively precipitated as a ~.Z~4~7 ,, 1 function of wt.% K2CO3 in a solution and the solution temper-2 ature.
4 The acidic components which will be removed from the gaseous mixture by the scrubbing process will preferably 6 be selected from the group consisting of CO2 alone or in . .~
7 combination with H2S, SO2, CS2, HCN, COS and the oxygen and 8 sulfur derivatives of Cl_C4 hydrocarbons.
9 The alkaline material comprising basic alkali salts or metal hydroxides will be selected from the group consist-11 ing of alkali metal bicarbonates, carbonates, hydroxides, 12 borates, phosphates and their mixtures.
13 The contacting of the absorbent mixture and the acid 14 gas may take place in any suitable contacting tower. In such processes, the gaseous mixture from which the acid gases are 16 to be removed may be brought into intimate contact with the 17 absorbing solution using conventional control means such as 18 a tower packed with, for example, ceramic rings or with bub-19 ble capped plates or sieve plates or a bubble reactor. In a preferred mode of practicing the invention, the absorption 21 step is conducted by feeding the gaseous mixture into the 22 base of the tower while the lean absorbing solution is fed 23 into the top. The gaseous mixture, free largely from acid 24 gases, emerges from the top. Preferably, the temperature of the absorbing solution during the absorption step is in 26 the range from about lS0F to about 270F and more preferably 27 from 150F to about 250F. Pressures may vary widely, accept-28 able pressures being between 5 and 2000 psig. In the desor-29 ber, the pressures will range from about 1 to 15 psig. The process can be better understood by reference to the follow-31 ing detailed description.
32 Referring to the figure, sour gas is introduced via 33 line 1 into ahsorption column 2 where it is contacted with 34 the aqueous scrubbing solution introduced via line 22. The scrubbing solution is at a temperature of about 200F and has 36 an amine concentration of from 1 to 10 wt.~, preferably 3 to ~L~.2~37 1 8 wt.~. As the absorbent li~uid passes down the absorber 2 column, acid gas impurities are absorbed.
3 The absorbent solution, enriched with acid gas im-4 purities, passes out of absorber column 2 into line 3 which passes the enriched solution through heat exchanger 4 into 6 line 5. Line 5 passes the enriched solution into the regen-7 erator 6 where the acid gases are stripped from the solution 8 and pass overhead through line 11. The lean solution formed 9 in the regenerator column passes to the bottom of column 6 and out via line 7 which feeds the lean solution to reboiler 11 8 where it is boiled by steam entering via line 9, the acid 12 vapors being passed via line 10 to the regenerator 6. The 13 lean ~essentially acid free) solution passes out of reboiler 14 8 via line 12. Line 12 passes the lean solution through pump 13 into line 14. Line 14 passes the lean solution into 16 heat exchanger 4 and some of the solution is cooled further 17 in heat exchanger 19 with cooling water entering via line 18 18 down to cool the solution to the temperature range in which 19 substantially only cyclic urea is precipitated. As used herein, the term "precipitate" is defined as particles which 21 are separated from the solution irrespective of whether the 22 particles would settle to the bottom of the solution or float 23 on top. In this process the cyclic urea removed from the 24 solution is less dense than the solution and hence will float on the surface. For a solution comprising about 30 wt.~
26 K2CO3 the solution should be preferably cooled to 180F to 27 120F, as indicated in Figure 2, more preferably to 160 28 to 130F, most preferably 150 to 135F to selectively pre-29 cipitate the cyclic urea degradation product while keeping all other components in the solution. Similarly, as shown in 31 Figure 2, a 25 wt.~ K2CO3 solution should be cooled to a 32 temperature ranging between 80F and 140F, preferably 90-33 120F, to selectivelv precipitate only the cyclic urea.
34 Maximum cooling effect for typical K2CO3 concentrations may be obtained by operation at a temperature in the range of 36 between 120F-80F. The solution containing the cyclic urea ~.2~37 g 1 solids is passed into line 15 which passes it to filter ele-2 ment 16. The cyclic urea degradation product accumulates on 3 the filter and is thereby selectively removed from the lean 4 solution. When the ultimate buildup of the insoluble mater-ial on the filter causes a pressure drop of, for example, 6 about 25 psi, a secondary filter 17 is cut in to allow con-7 tinued operation of the process during the cleaning of the 8 segregated filter.
9 The lean solution passes out of filter 16 via line 23 and joins with some of the other lean solution in line 21 11 which was not cooled by exchanger 19. These two streams 12 combine and enter the top of the absorber. The purified 13 gas passes out of absorber 2 via line 24. Hot water having 14 a temperature of about 230F is passed via line 20 into filter element 16 in order to wash the cyclic urea from the 16 filter and to permit its effective reuse.
18 The following is a summary of several examples 19 which describe the invention.
21 A gas treating solution was prepared which had the 22 following composition: 30 wt.% K2CO3 (with 10% as KHC03).
23 6.0 wt.% cyclohexyl-1,3-propane diamine, 6.1 wt.% pipecolinic 24 acid, 56.2 wt.% water, and 1.7 wt.% cyclic urea, i.e., 25 1-cyclohexyl-hexahydro-2-pyrimidinone. The solution at 200F
26 was present as a single liquid phase. This solution was then 27 cooled at 150F and was passed over a filter element which 28 was a cotton wound element having a nominal 100~ size. The 29 cyclic urea content was decreased from 1.7 wt.% to less than 1.0 wt.~. The filtration rate was 0.5 gpm and the filter 31 size was a 3" diameter cylinder, 4" high with an inner opening 32 of about 1" diameter. The filter cake was analyzed to be 33 pure cyclic urea with none of the other solution components 34 present. This example shows that the cyclic urea can be selectively removed by this process. It is not necessary to 36 completely remove all the cyclic urea but just to be able :, ` 1 to keep the concentration at a nomimally low level even though 2 it is constantly being produced within the process.
4 The gas treating solution described in Example 1 was cooled to 130F at which point considerably more cyclic 6 urea came out of the solution. Operation of the process at ~; 7 these conditions, however, produced a somewhat inoperable 8 condition due to the plugging tendency of the resulting pre-9 cipitate. In the flowing system in which the stream is being continuously filtered such a line plugging tendency as 11 observed above made the system somewhat inoperable. Therefore, 12 this test indicated that for this solution cooling to below 13 130F leads to an undesired operability problem. The solids 14 which were filtered during the test were again found to be pure cyclic urea with none of the other components of the 16 solution present.
17 EXAMæLE 3 .
18 Another gas treating solution was prepared that was 19 similar to that shown in Example 1 but which had about 30~ of the K2CO3 present as KHC03. In this solution, cooling from 21 200F to 150F again caused the cyclic urea to selectively 22 precipitate from the solution. As the solution was further 23 cooled to somewhat below 100F, it was found that the pro-24 cess was no longer selective in that in addition to the cyclic urea precipitating out, KHC03 was also precipitated 26 out. This test further shows the critical temperature range 27 over which the cyclic urea selectively precipitates. If the 28 temperature goes below about 100F, the process is no longer 29 selective. The filter cake in this test was found to contain substantial amounts of KHCO3.
32 Another gas treating solution was prepared which 33 had a composition similar to that shown in Example 1 except 34 that the cyclic urea content was 1.4 wt.~o. This solution was cooled to 148F and was filtered using a filter arrange-36 ment as described in Example 1 but with a 5~ element rather ~ 2~7 1 than the 100~ element. The run was carried out at 0.5 gpm 2 and the filter cake collected was analyzed and was found to 3 be pure cyclic urea. In this test, the run was carried out 4 until the pressure drop across the element reached about 25 psi.
7 After completion of the run described in Example 4 8 the filter had a pressure drop of 25 psi due to the cyclic 9 urea cake on the filter element. This cake was washed with 170F water and a second cycle was attempted in which case 11 a run of only about 25% as long as the initial run occurred.
12 This indicated that the washing with 170F water was not an 13 effective cleaning process. The filter was then washed with 14 230F water and then another cycle was attempted. In this case, the cycle length was equivalent to that of the initial 16 cycle on the fresh filter. Three more complete cycles were 17 run in which the filter cake was washed with 230F water 18 after a 25 psi pressure drop had built up due to the accumu-19 lation of the cyclic urea cake. In each case the amount of cyclic urea removed was the same as that with a new filter.
21 These tests indicated an effective washing techni~ue in which 22 the water temperature criticality was demonstrated.
24 Another gas treating solution was prepared compris-ing: 25 wt.~ K2CO3 (with 20% of this present as KHCO3), 6.3 26 wt.% cyclohexyl-1,3-propane diamine, 3 wt.~ pipecolinic acid, 27 0.8 wt.% cyclic urea and the balance water. The solution was 28 then cooled to about 85F. The filter cake was collected, 29 analyzed, and found to be substantially pure cyclic urea.
Although the subject process has been described with 31 reference to a specific embodiment, it will be understood that 32 it is capable of further modification. Any variations, uses 33 or adaptations of the invention following, in general, the 34 principles of the invention are intended to be covered, including such departures from the present disclosure as come 36 within known or customary practice in the art to which the ~,~ Z~7 1 invention pertains and as may be applied to the essential 2 features hereinbefore set forth, and as fall within the scope 3 of the invention.
Claims (15)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An acid gas scrubbing process providing for the selective removal of a cyclic urea reaction product which forms as a by-product of the acid gas removal, said process comprising:
a. contacting an acid gas mixture with an aqueous solution in an absorption zone, said aqueous solution comprising a basic alkali salt, or metal hydroxide selected from the group consisting of alkali metal bicarbonates, carbonates, hydroxides, borates, phosphates and their mixtures, and an activator for said basic salt comprising at least one sterically hindered amine having the generic formula:
R-NH-(CH2)m-NH2 where R is a secondary or tertiary alkyl or cycloalkyl hydro-carbon having 4 - 20 carbon atoms and m is 2 - 5, at elevated temperatures and pressures such that there is formed a cyclic urea reaction product having the formula:
where R is a secondary or tertiary alkyl or cycloalkyl hydro-carbon having 4 - 20 carbon atoms and m is 0 - 3;
b. passing said acid gas rich aqueous solution to a regeneration zone where it is contacted with steam to remove the acid gas impurities therefrom;
c. cooling a portion of the lean solution exiting from said regeneration zone to a temperature ranging from 180 80°F. to selectively precipitate the cyclic urea from said lean solution;
d. passing said lean solution containing said pre-cipitated cyclic urea to a separation zone to remove at least a portion of the cyclic urea from said lean solution.
a. contacting an acid gas mixture with an aqueous solution in an absorption zone, said aqueous solution comprising a basic alkali salt, or metal hydroxide selected from the group consisting of alkali metal bicarbonates, carbonates, hydroxides, borates, phosphates and their mixtures, and an activator for said basic salt comprising at least one sterically hindered amine having the generic formula:
R-NH-(CH2)m-NH2 where R is a secondary or tertiary alkyl or cycloalkyl hydro-carbon having 4 - 20 carbon atoms and m is 2 - 5, at elevated temperatures and pressures such that there is formed a cyclic urea reaction product having the formula:
where R is a secondary or tertiary alkyl or cycloalkyl hydro-carbon having 4 - 20 carbon atoms and m is 0 - 3;
b. passing said acid gas rich aqueous solution to a regeneration zone where it is contacted with steam to remove the acid gas impurities therefrom;
c. cooling a portion of the lean solution exiting from said regeneration zone to a temperature ranging from 180 80°F. to selectively precipitate the cyclic urea from said lean solution;
d. passing said lean solution containing said pre-cipitated cyclic urea to a separation zone to remove at least a portion of the cyclic urea from said lean solution.
2. The process of claim l wherein said sterically hindered amine is an N-alkyl alkylene diamine.
3. The process of claim 2 wherein said lean solu-tion exiting from said regeneration zone is cooled to tempera-tures ranging from 130° - 100°F.
4. The process of claim 3 wherein said sterically hindered amine is cyclohexyl-1,3-propane diamine.
5. The process of claim 4 wherein said lean solu-tion exiting from said regeneration zone is cooled to tempera-tures ranging from 135° - 150°F.
6. The process of claim 5 wherein said cyclic urea is removed by passing said lean solution through separation media comprising porous filters or activated carbon beds.
7. The process of claim 5 wherein the accumulation of said cyclic urea on said filter is monitored until the pres-sure drop across said filter reaches about 25 psi at which time said filter is segregated and a second filter is substituted therefor.
8. An acid gas scrubbing process providing for the selective removal of a cyclic urea reaction product which forms as a by-product of the acid gas removal, said process comprising:
a. contacting an acid gas mixture with an aqueous solution in an absorption zone, said aqueous solution comprising a basic alkali salt, or metal hydroxide selected from the group consisting of alkali metal bicarbonates, carbonates, hydroxides, borates, phosphates and their mixtures, and an activator for said basic salt comprising at least one sterically hindered amine hav-ing the generic formula:
R-NH-(CH2)m NH2 where R is a secondary or tertiary alkyl or cycloalkyl hydrocar-bon having 4 - 20 carbon atoms and m is 2 - 5, at elevated tem-peratures and pressures such that there is formed a cyclic urea reaction product having the formula:
where R is a secondary or tertiary alkyl or cycloalkyl hydro-carbon having 4 - 20 carbon atoms and m is 0 - 3:
b. passing said acid gas rich aqueous solution to a regeneration zone where it is contacted with steam to remove the acid gas impurities therefrom;
c. cooling a portion of the lean solution exiting from said regeneration zone to a temperature ranging between 120° - 80°F. to selectively precipitate the cyclic urea from said lean solution;
d. passing said lean solution containing said precipi-tated cyclic urea to a separation zone to remove at least a portion of the cyclic urea from said lean solution.
a. contacting an acid gas mixture with an aqueous solution in an absorption zone, said aqueous solution comprising a basic alkali salt, or metal hydroxide selected from the group consisting of alkali metal bicarbonates, carbonates, hydroxides, borates, phosphates and their mixtures, and an activator for said basic salt comprising at least one sterically hindered amine hav-ing the generic formula:
R-NH-(CH2)m NH2 where R is a secondary or tertiary alkyl or cycloalkyl hydrocar-bon having 4 - 20 carbon atoms and m is 2 - 5, at elevated tem-peratures and pressures such that there is formed a cyclic urea reaction product having the formula:
where R is a secondary or tertiary alkyl or cycloalkyl hydro-carbon having 4 - 20 carbon atoms and m is 0 - 3:
b. passing said acid gas rich aqueous solution to a regeneration zone where it is contacted with steam to remove the acid gas impurities therefrom;
c. cooling a portion of the lean solution exiting from said regeneration zone to a temperature ranging between 120° - 80°F. to selectively precipitate the cyclic urea from said lean solution;
d. passing said lean solution containing said precipi-tated cyclic urea to a separation zone to remove at least a portion of the cyclic urea from said lean solution.
9. The process of claim 8 wherein said sterically hindered amine is an N-alkyl alkylene diamine.
10. The process of claim 9 wherein said lean solution exiting from said regeneration zone is cooled to temperatures ranging between 90° - 120° F.
11. The process of claim 10 wherein said sterically hindered amine is cyclohexyl-1,3-propane diamine.
12. The process of claim 11 wherein said cyclic urea is removed by passing said lean solution through separation media comprising porous filters or activated carbon beds.
13. The process of claim 11 wherein the accumulation of said cyclic urea on said filter is monitored until the pressure drop across said filter reaches about 25 psi at which time said filter is segregated and a second filter is substituted therefor.
14. The process of claim 1 or 8 wherein a loading of about 1 to about 10 SCF of acid gas per gallon of said aqueous solution is achieved in step (a).
15. The process of claim 1 or 8 wherein the regeneration zone in step (b) is operated at temperatures ranging from about 200°F to about 250°F and pressures ranging from about 1 psig to about 15 psig.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/972,500 US4180548A (en) | 1978-12-22 | 1978-12-22 | Process for selective removal of cyclic urea from hindered amine gas treating solution |
| US972,500 | 1978-12-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1124487A true CA1124487A (en) | 1982-06-01 |
Family
ID=25519720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA342,448A Expired CA1124487A (en) | 1978-12-22 | 1979-12-21 | Process for selective removal of cyclic urea from hindered amine gas treating solution |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4180548A (en) |
| EP (1) | EP0013151B1 (en) |
| JP (1) | JPS5597227A (en) |
| AU (1) | AU530894B2 (en) |
| BE (1) | BE884129Q (en) |
| BR (1) | BR7908473A (en) |
| CA (1) | CA1124487A (en) |
| DE (1) | DE2966382D1 (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4292286A (en) * | 1978-12-22 | 1981-09-29 | Exxon Research & Engineering Co. | Process for selective removal of cyclic urea from hindered amine gas treating solution |
| DE3165315D1 (en) * | 1980-02-19 | 1984-09-13 | Exxon Research Engineering Co | Acid gas scrubbing process using hindered amine solution with hindered amine recovery from side-product cyclic urea |
| US4282193A (en) * | 1980-02-19 | 1981-08-04 | Exxon Research & Engineering Co. | Process for converting cyclic urea to corresponding diamine in a gas treating system |
| US4282194A (en) * | 1980-02-19 | 1981-08-04 | Exxon Research & Engineering Co. | Process for converting cyclic urea to corresponding diamine in a gas treating system |
| US4341746A (en) * | 1981-06-01 | 1982-07-27 | Exxon Research & Engineering Co. | Removal of degradation product from gas treating solution |
| US4405586A (en) * | 1981-11-13 | 1983-09-20 | Exxon Research And Engineering Co. | N-Secondary butyl glycine promoted acid gas scrubbing process |
| US4405579A (en) * | 1981-11-13 | 1983-09-20 | Exxon Research And Engineering Co. | Sterically hindered amino acids and tertiary amino acids as promoters in acid gas scrubbing processes |
| JP2005008478A (en) * | 2003-06-18 | 2005-01-13 | Toshiba Corp | Carbon dioxide recovery system and carbon dioxide recovery method in exhaust gas |
| WO2005072851A1 (en) * | 2004-01-30 | 2005-08-11 | Kabushiki Kaisha Toshiba | System and method for recovering carbon dioxide in exhaust gas |
| WO2006016979A1 (en) * | 2004-07-12 | 2006-02-16 | Exxonmobil Upstream Research Company | Methods for removing sulfur-containing compounds |
| CN100344378C (en) * | 2005-11-30 | 2007-10-24 | 曹志德 | Desulfur denitrogen catalyst of fuel coal, fuel oil boiler smoke and its desulfur denitrogen method |
| EP2409755A1 (en) * | 2010-07-22 | 2012-01-25 | Siemens Aktiengesellschaft | Method and device for processing an impure alkaline solution of an amino acid salt |
| JP5693295B2 (en) * | 2011-02-28 | 2015-04-01 | 三菱重工業株式会社 | CO2 recovery device and operation control method of CO2 recovery device |
| JP5117612B2 (en) * | 2011-11-30 | 2013-01-16 | 株式会社東芝 | Carbon dioxide recovery device |
| JP6216259B2 (en) * | 2014-02-05 | 2017-10-18 | 三菱重工業株式会社 | CO2 recovery device and cleaning method for filtration membrane device of CO2 recovery device |
| RU2621754C1 (en) * | 2016-08-15 | 2017-06-07 | Игорь Анатольевич Мнушкин | Method of absorption cleaning of hydrocarbon gas from acid components |
| US11207634B2 (en) | 2018-07-02 | 2021-12-28 | University Of Kentucky Research Foundation | Apparatus and method for recovering an amine solvent from an acid gas stream |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2497309A (en) * | 1944-05-04 | 1950-02-14 | Du Pont | Process for the preparation of ethyleneurea |
| US2615025A (en) * | 1951-10-18 | 1952-10-21 | Olin Mathieson | Process for the preparation of ethylene urea |
| US2874149A (en) * | 1957-03-18 | 1959-02-17 | Monsanto Chemicals | Ureas |
| GB1449039A (en) * | 1973-10-23 | 1976-09-08 | Trentham Corp | Method of separating sulphur dioxide from gaseous mixtures |
| AU506199B2 (en) * | 1975-06-26 | 1979-12-20 | Exxon Research And Engineering Company | Absorbtion of co2 from gaseous feeds |
| US4094957A (en) * | 1976-12-14 | 1978-06-13 | Exxon Research & Engineering Co. | Process for removing acid gases with hindered amines and amino acids |
-
1978
- 1978-12-22 US US05/972,500 patent/US4180548A/en not_active Expired - Lifetime
-
1979
- 1979-12-20 DE DE7979302994T patent/DE2966382D1/en not_active Expired
- 1979-12-20 EP EP79302994A patent/EP0013151B1/en not_active Expired
- 1979-12-21 BR BR7908473A patent/BR7908473A/en not_active IP Right Cessation
- 1979-12-21 AU AU54159/79A patent/AU530894B2/en not_active Ceased
- 1979-12-21 CA CA342,448A patent/CA1124487A/en not_active Expired
- 1979-12-22 JP JP16745279A patent/JPS5597227A/en active Granted
-
1980
- 1980-07-02 BE BE0/201274A patent/BE884129Q/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6311928B2 (en) | 1988-03-16 |
| EP0013151B1 (en) | 1983-11-02 |
| BR7908473A (en) | 1980-08-26 |
| JPS5597227A (en) | 1980-07-24 |
| US4180548A (en) | 1979-12-25 |
| DE2966382D1 (en) | 1983-12-08 |
| AU5415979A (en) | 1980-06-26 |
| EP0013151A1 (en) | 1980-07-09 |
| BE884129Q (en) | 1981-01-05 |
| AU530894B2 (en) | 1983-08-04 |
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