Abstract: A system including a feedstock supply system that includes a first pump configured to supply a first feedstock to a first gasifier along a first supply conduit, a second pump configured to supply a second feedstock to the first gasifier along a second supply conduit, and a pressure vessel disposed along a first conduit loop. The feedstock supply system is configured to circulate the first feedstock through the first conduit loop to raise a first pressure of the first feedstock to a first threshold pressure in the pressure vessel. The feedstock supply system is also configured to control a first transition from the second pump to the first pump after the first pressure reaches the first threshold pressure. The first transition includes a first change from the second feedstock to the first feedstock for supply to the first gasifier.