Here's some (untested) skeleton code which should get you going.

. . .
use constant TIME_FIELD => 1;
. . .
# Read this data from a config file
my %periods = qw(08:45:00 12:00:00 02:00:00 17:00:00);
. . .
while (my $line = <TAB_DEL_FILE>)
{
    chomp $line;
    my @data = split /\t/, $line;
    my $time = $data[TIME_FIELD];
    foreach my $start (keys %periods)
    {
        next unless $time ge $start && $time le $periods{$start};
        process_line(\@data);
        last;
    }
}
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