US 9,919,262 B2  18  17  TABLE 6  Tests at 30  min  Chemical  solvent  Mixture  of Hep  Physical  Lean  Regeneration  Emission  Energy  and  solvent  mole/ Lean Rich Delta  Cp  MJ/kg  DiHep  Polyol  mole  %  %  %  kJ/kg K  SO2  25  0  0.12  1.49  4.4  2.6  3.5  17.4  25  5  0.14  1.58  4.1  2.5  3.4  15.0  22  8  0.12  1.55  4.3  2.7  3.4  14.6  18  14  0.07  0.99  3.6  2.6  3.4  14.6  TetraEG  wt%  25  15  0.11  1.29  4  2.7  3.2  14.6  25  25  0.08  0.93  3.6  2.6  3  17.2  BP  Ppm  saving  CC.  SO2  %  112  124  0  113  208  113  179  113  119  16  115  137  16  117  99  0  For the test done at 30 g/min (Table 5), solutions con› taining PEGDME, with similar Cp, boiling points, and  similar regeneration energies, showed a decrease in SO2  emission from 208 to 119 ppm as the amount of PEGDME  increased from 5% to  14%  in the solution.  Each solution tested comprising a mixture of chemical  and physical solvents, except the solution comprising 25 wt  % of the mixture of Hep and DiHep and 5 wt% PEGDME,  provided a reduction in regeneration energy consumption  compared to the bench mark solution. The results of the  solution comprising 25 wt % of the mixture of Hep and  DiHep, the solution comprising 18 wt % of the mixture of  Hep and DiHep and  14  wt% PEGDME, and the solution  comprising 18 wt % of the mixture of Hep and DiHep and  15 wt% TetraEG shown in Tables  4  to  6  are also represented  as FIG.  2.  4.  PEGDME Solubility Versus Amine and Salts Levels  Table 7 shows the relationship between the level of HSS  and PEGDME solubility when the amine concentration is  the same: for the solution having 13 wt% the mixture of Hep  and DiHep, the level of miscible PEGDME was 22 wt% at  1  equivalent/amine mole HSS versus 17 wt% at 1.2 equiva› lent/amine mole HSS. Table 7 also shows that for the same  level of HSS, the amine concentration also influences the  miscibility of PEGDME to maintain a one-phase solution:  for the solution containing 25 wt % the mixture of Hep and  DiHep to maintain a one-phase solution, the maximum  concentration of PEGDME was 5 wt %; whereas when the  concentration of the mixture of Hep and DiHep was at 13 wt  %, the maximum concentration of PEGDME rose to 17 wt  %.  A polyol like TetraEG did not show solubility limitation  versus amine concentration and TriEGMME showed inter› mediate solubility. Without being limited by theory, it is  believed that hydroxyl groups may confer better solubility  than methyl groups.  Tetraethylene glycol (TetraEG)  Polyethyleneglycol dimethylether (PEGDME)  A compilation of molecular structure diagrams of the  chemicals used in the various solutions described above is as  follows.  Solution A-TetraEG, which is an aqueous solution com- prising 25 wt % the mixture of Hep and DiHep, 15 wt %  TetraEG, and 1.2 equivalent/amine mole HSS.  Solution A-TriEGMME, which is an aqueous solution  comprising 25 wt % the mixture of Hep and DiHep, 12 wt  % TriEGMME, and 1.2 equivalent/amine mole HSS; and  Solution D, which is an aqueous solution comprising 22  wt% 3-aminopyrazole, 32 wt% PEGDME, and  0.1  equiva- lent/amine mole HSS;  Solution C, which is an aqueous solution comprising 25  wt% Amide-DiHep, 20 wt% PEGDME, and 0.4 equivalent/  amine mole HSS;  Solution B, which is an aqueous solution comprising 18  wt% the mixture of Hep and DiHep,  14  wt% PEGDME,  and 1.2 equivalent/amine mole HSS;  Solution DABCO, which is an aqueous solution compris- ing 25 wt % DABCO and  1.0  equivalent/amine mole HSS;  Solution A-Org, which is an aqueous solution comprising  25 wt% the mixture of Hep and DiHep, 20 wt% malic acid,  and  6  wt % NaOH;  Solution A, the benchmark solution, which is an aqueous  solution comprising 25 wt % the mixture of Hep and DiHep  and 1.2 equivalent/amine mole HSS;  The following solutions were tested:  5.1 Tested Solutions  5. Test 2  TABLE 7  PEGDME solubility in the mixture of Hep and DiHep  Mixture of Hep  and DiHep  HSS  PEGDME  wt%  equi/mole  wt%  13  22  13  1.2  17  18  1.2  14  22  1.2  8  25  1.2  5  /o~ 0 ~o~ 0 HO~o~o~o~OH  -........._ 0 ~o~ 0