Yes, there are plants that feed sludge during coking and quenching. The pretreatment requirements vary by the type of sludge being processed. The original systems were called iMOSC for water sludge injection. Most sites will mill the sludge to have a more uniform particle size, typically <100 micron, and are kept in suspension in at least 50% water. Personally, I like 75%+ water to prevent equipment wear. Injection quantities are typically limited by drum temperature to ensure smelly molecules are destroyed or recovered. Again, temperature numbers vary but >650F is a good start.
