After you do cwe, can you evaporate the water by boiling it to leave some kind of powder behind? so you could rail it? Would that work or just waste the pills. BTW I'm using oxycodone.
I'm pretty sure most opiates deteriorate with heat, your best bet would be to pour it into a large glass baking dish and let the water evaporate that way,
Put a fan on it in a shallow dish and it will evap. Not much use in taking the time though. If its for trasport just put it in GFJ bottle with some of the juice poured out. Kills most of the taste and helps it along. Making it powder is just a novelty.
30ml of water will take about 5-10 mins to evaporate on the lowest heat setting, you will want to leave it a bit moist as it will take time to cool and you might burn the solution. it does work but as indicameds said, it is just a novelty unless you need to take some along for a few days and can't do a cwe/can't keep it cold enough to prevent mold and bacteria.
Most opiates are very sensetive to light and heat if you are desperate to dry it out and don't mind waiting I would suggest using a pan/container with a large surface area and leaving it in a warm dark place for a few days then you can just scrape up the powder.
I myself have considered doing this with large amounts of DHC 1g+ so I can just capsual it up and take when needed