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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 %. 

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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. 

5. Test 2 

5.1 Tested Solutions 

The following solutions were tested: 

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; 

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 DABCO, which is an aqueous solution compris- ing 25 wt % DABCO and 1.0 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 C, which is an aqueous solution comprising 25 wt% Amide-DiHep, 20 wt% PEGDME, and 0.4 equivalent/ amine mole HSS; 

Solution D, which is an aqueous solution comprising 22 wt% 3-aminopyrazole, 32 wt% PEGDME, and 0.1 equiva- lent/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 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. 

A compilation of molecular structure diagrams of the chemicals used in the various solutions described above is as follows. 

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Polyethyleneglycol dimethylether (PEGDME) 

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Tetraethylene glycol (TetraEG) 

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