What is it the DCU process condition in order to reduce the Heavy Coker gasoil production ? We are having problem to reroute the HKGO in the refinery. So, we need to reduce the HKGO production. We changed the DCU process conditions but we still need to reduce the HKGO. What happens with the other Coker Streams in terms of quality and yield ?
Anything that is done to reduce the HKGO yield will increase the coke yield and the yield of the other liquid products as a percent of feed. Increasing drum pressure, increasing recycle ratio and reducing heater outlet temperatures will reduce the HKGO yield. You need to be careful about lowering heater outlet temperatures as that can result in unconverted oil left in the coke drum that causes the quenching of the coke bed to be incomplete or inadequate and the resulting hot spots will case eruptions or blow-outs.
Routing the HKGO back to the unit feed will result in recycling that stream to extinction. Heater outlet temperatures will need to be increased to ensure all the HKGO is cracked in the coke drum and the resid is fully converted in the drum.
The quality of the other streams does not vary much; however, they yields increase to make up for the elimination of the HKGO stream. As the coke precursors in the HKGO stream are low, the increase in coke yield is modest, 1% to 2% would be a reasonable guess. The rest of the HKGO stream distributes between the other liquid products.