A system and method for devolatilizing a carbonaceous feedstock are provided. The system includes a devolatilization reactor having a unit shell, at least one tube bundle, a pump, and a control valve. The unit shell is configured to allow a heating fluid to flow within. The at least one tube bundle is configured to allow the feedstock to flow within the tube bundle and further configured to be positioned at least partially within the unit shell. The tube bundle comprises at least one tube and at least one tube bend. The at least one tube bend is disposed external to the unit shell. The pump is configured to pump the feedstock into the at least one tube bundle. The control valve is configured to control the flow rate of feedstock into the at least one tube bundle.