The calculated distance (air line) between Bernkastel-Kues and Duisburg is approximately 106 miles respectively 170 kilometers.
By car or train, the actual journey to Duisburg is certainly longer, as only the direct route (as the crow flies) between Bernkastel-Kues and Duisburg has been calculated here.
Air line (approximately)
170 kilometers
92 nautical miles