Kempsell had battled back from two games down to win his first match but there was no escape from a straight games 8-11 7-11 8-11 defeat from American Nick Schreiber. But Greg Lobban, from Inverness, kept the home flag flying in the senor event.
Lobban won an all-Scottish quarter-final against Crieff's Ewen Urquhart 11-9 11-7 11-8 and now faces another Scot in Aberdeen's Ally McCorquodale.
In a bad-tempered match, McCorquodale, the No.?5 seed, scored an upset 9-11 13-11 11-6 11-6 victory over the third seed from Egypt, Omar Kheiralla.
Lobban's younger sister, Kirsty, remained on curse to retain the girls' under-15 title. She cruised through to the semi-finals with an 11-8, 11-6, 11-4 victory over Spain's Cristina Gomez Jiminez.
In the other semi-final, Crieff's Clare Gadsby will face the top seed from Egypt, Radwa Adel.