A conveying and lock system (10) for introducing a bulk material into a reactor (14) with exclusion of gas and while preventing gas exchange at low pressure differences has a screw shaft (44) on which first windings (46) and second windings (48) are formed. A winding-free section (50) is disposed between the first and the second windings (46, 48) in which the conveyed bulk material is compacted. The compacting causes a bulk material plug which is substantially gas free and, during bulk material transport, the bulk material plug is constantly formed in the conveying and lock system (10) by the screw shaft (44) to prevent gas exchange between the product inlet and the product outlet of the conveying and lock system.