Chysis laevis Lindl.
OC = Own Collection
This orchid opened three flowers, which were open only a few days. I suspect that they self-pollinated somehow, but I'm not sure. (They now have "thick" fruit-like parts.) I couldn't detect any smell.
Chysis is in subtribe Bletiinae according to Wikipedia, and in subtribe Chysinae according to Genera Orchidacearum Vol. 4. I couldn't find how the RHS classifies it. In any case, the genus is in tribe Epidendreae, which also includes subtribe Laeliinae.
Cheers!