Can I install a double chainset on a bike that was originally designed for a triple chainset?
You'll need a new bottom bracket with a different axle length, a new crankset of course, front derailleur and matching shifter. Since you'll probably need to buy a complete set of brifters it will be quite an expense. And while you're at it you'll probably have to get new cable housings and cables for the brakes. Not to mention new bar tape. At least you can keep the rear derailleur  and  the cassette if the resulting new gears suit you, but you may need a new chain.

And if your triple has less than 10 gears on the cassette you'll probably have to find an older double crankset and matching shifters.

INMHO I would keep the bike as it is because the expense will be quite hefty.