Immersion heater for IPA recycling purposes

Hi, we are searching for a 3-6kw immersion heater to heat and keep at a boil a water-IPA mixture for IPA recycling purposes. It is crucial that the heater does not burn out during steaming process, which takes 4hrs+ (heater constantly on). Metal immersion heaters have already been put to use, and result in burning out after just a few runs. Your help would truly be appreciated. thanks and regards,Joseph