Please cite your source as this data does not make sense.45 Celsius is the boiling point of pure (and non-polymerized) sulphur trioxide.
I specified sufficiently concentrated.
Boiling point of concentrated hydrochloric acid drops rapidly with concentration:
20 % - 108 C
30 % - 90 C
32 % - 84 C
34 % - 71 C
36 % - 61 C
38 % - 48 C
42 % - 20 C
45 % - 0 C
48 % - -18 C
The hydrochloric acid sold by retail seems to go to 32 %, which boils at 90 %.
Scroll up at the post where hydrogen chloride generator is used to feed a funnel... there filled with NaCl/H2SO4 mixture, and heated.
Well, you can use the same arrangement to generate gaseous hydrogen chloride by heating hydrochloric acid above 20 %! Say, 32 % acid would give off mostly HCl and little water Thus you can distil one portion of 32 % acid down to 30 % and absorb the fumes into the other portion of 32 % acid which you are cooling. So you can get from two portions of 32 % acid a portion of 30 % and a portion of 34 % acid. Or if the portions are different size and you are using enough cooling of the second portion, as much as 48 % acid.