The calculated distance (air line) between Mülheim-Kärlich and Duisburg is approximately 79 miles respectively 127 kilometers.
By car or train, the actual journey to Duisburg is certainly longer, as only the direct route (as the crow flies) between Mülheim-Kärlich and Duisburg has been calculated here.
Air line (approximately)
127 kilometers
69 nautical miles