**Using helper cell B2**
With value in A2

formula in B2

=SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A2,"hr",":"),"min",":"),"sec","")," ","")

formula in C2

=IF(B2>TIME(24,0,0),TEXT(B2,"[h]:mm:ss")*24*60*60,B2)

**single formula**
formula in B2

=IFERROR(VALUE(LEFT($A2,SEARCH("hr",$A2)-1)),0)*3600+VALUE(LEFT(IFERROR(RIGHT($A2,LEN($A2)-SEARCH("hr",$A2)-2),$A2),2))*60+VALUE(TRIM(SUBSTITUTE(RIGHT($A2,6),"sec","")))

the second option could probably be simplified

EDIT

here's a start!

=IFERROR(LEFT($A2,SEARCH("hr",$A2)-1),0)*3600+LEFT(IFERROR(RIGHT($A2,LEN($A2)-SEARCH("hr",$A2)-2),$A2),2)*60+TRIM(SUBSTITUTE(RIGHT($A2,6),"sec",""))