A feed supply unit comprising (a) a feed dosage unit for supplying a viscosity unstable liquid feed to a reactor, and (b) a flushing unit for flushing at least a part of the feed dosage unit according to (a) with a flushing medium, wherein the feed dosage unit according to (a) comprises (a.i) a feed dosage device for dosing the feed into a chemical reactor; (a.ii) a feed pump located upstream of the feed dosage device according (a.i); (a.iii) a feed pipe connecting the feed pump according to (a.ii) and the feed dosage device according to (a.i); (a.iv) a feed supply pipe, located upstream of the feed pump according to (a.ii) and ending in the feed pump according to (a.ii); (a.v) monitoring means for monitoring at least one operating parameter of the feed dosage unit; wherein the flushing unit according to (b) comprises (b.i) a flushing medium tank and means for pressurizing the flushing medium tank; (b.ii) a flushing medium pipe comprising a controllable flow-through device for adjusting the flow rate of the flushing medium from the flushing medium tank according to (b.i) to the feed dosage unit according to (a) and connecting the flushing medium tank and at least one of - the feed dosage device according to (a.i), - the feed pump according to (a.ii), - the feed pipe according to (a.iii), and - the feed supply pipe according to (a.iv); (b.iii) control means for controlling the controllable flow-through device according to (b.ii) based on the at least one parameter monitored by the monitoring means according to (a.v); wherein the feed supply unit further comprises (c) signal transmission means for transmitting a signal from the monitoring means according to (a.v) to the control means according to (b.iii). (a) a feed dosage unit for supplying a viscosity unstable liquid feed to a reactor, and (b) a flushing unit for flushing at least a part of the feed dosage unit according to (a) with a flushing medium, wherein the feed dosage unit according to (a) comprises (a.i) a feed dosage device for dosing the feed into a chemical reactor; (a.ii) a feed pump located upstream of the feed dosage device according (a.i); (a.iii) a feed pipe connecting the feed pump according to (a.ii) and the feed dosage device according to (a.i); (a.iv) a feed supply pipe, located upstream of the feed pump according to (a.ii) and ending in the feed pump according to (a.ii); (a.v) monitoring means for monitoring at least one operating parameter of the feed dosage unit; wherein the flushing unit according to (b) comprises (b.i) a flushing medium tank and means for pressurizing the flushing medium tank; (b.ii) a flushing medium pipe comprising a controllable flow-through device for adjusting the flow rate of the flushing medium from the flushing medium tank according to (b.i) to the feed dosage unit according to (a) and connecting the flushing medium tank and at least one of - the feed dosage device according to (a.i), - the feed pump according to (a.ii), - the feed pipe according to (a.iii), and - the feed supply pipe according to (a.iv); (b.iii) control means for controlling the controllable flow-through device according to (b.ii) based on the at least one parameter monitored by the monitoring means according to (a.v); wherein the feed supply unit further comprises (a.i) a feed dosage device for dosing the feed into a chemical reactor; (a.ii) a feed pump located upstream of the feed dosage device according (a.i); (a.iii) a feed pipe connecting the feed pump according to (a.ii) and the feed dosage device according to (a.i); (a.iv) a feed supply pipe, located upstream of the feed pump according to (a.ii) and ending in the feed pump according to (a.ii); (a.v) monitoring means for monitoring at least one operating parameter of the feed dosage unit; wherein the flushing unit according to (b) comprises (b.i) a flushing medium tank and means for pressurizing the flushing medium tank; (b.ii) a flushing medium pipe comprising a controllable flow-through device for adjusting the flow rate of the flushing medium from the flushing medium tank according to (b.i) to the feed dosage unit according to (a) and connecting the flushing medium tank and at least one of - the feed dosage device according to (a.i), - the feed pump according to (a.ii), - the feed pipe according to (a.iii), and - the feed supply pipe according to (a.iv); - the feed dosage device according to (a.i), - the feed pump according to (a.ii), - the feed pipe according to (a.iii), and - the feed supply pipe according to (a.iv); (b.iii) control means for controlling the controllable flow-through device according to (b.ii) based on the at least one parameter monitored by the monitoring means according to (a.v); wherein the feed supply unit further comprises (c) signal transmission means for transmitting a signal from the monitoring means according to (a.v) to the control means according to (b.iii).