Partial oxidation process

A method for controlling a partial oxidation process in which one reactant fuel stream is replaced by another without shutting down or depressurizing the system comprising:

• (1) separately sensing the flow rates of four feedstreams 1-4 respectively consisting of steam, stand-by fuel, principal fuel, and free-oxygen containing gas, and providing signals s, m, a, and b corresponding respectively to the actual flow rates of feedstreams 1-4 to a control unit;
• and wherein said principal fuel comprises a pumpable slurry feed stream of solid carbonaceous fuel in a liquid carrier in liquid phase and having a solids content in the range of about 30 to 75 wt. % and said standby fuel comprises a liquid hydrocarbonaceous fuel stream;
• (2) comparing said actual flow rate signals s, m, a, and b respectively with manual or automatically computed and inserted input signals representing the desired flow rate or set point for that moment for each of the four feedstreams, and providing a corresponding adjustment signal to a flow rate control means for controlling the flow rate of each feedstream 1-4 in accordance with the respective set point of each;
• (3) passing a feedstream of said principal fuel into the reaction zone of a free flow noncatalytic partial oxidation gas generator, by way of a free flow annular passage of a burner comprising a central conduit coaxial with the central longitudinal axis of said burner and having a downstream exit orifice that discharges into a premix zone, said central conduit providing passage, an outer coaxial conduit providing said free-flow annular passage along the length of said central conduit between the inside diameter of said outer conduit and the outside diameter of said central conduit, an exit nozzle terminating said outer conduit at the downstream end of said burner comprising a converging frusto-conical rear portion and a right cylindrical front portion which terminates at the downstream face of the burner, an annular shaped face-cooling chamber surrounding said exit nozzle at the burner tip, and wherein the tip of said central conduit is retracted upstream from the face of said burner a distance of two or more times the minimum diameter of said outer conduit converging exit nozzle to provide said pre-mix zone comprising one or more cylindrically shaped communicating pre-mix chambers in tandem and coaxial with the central longitudinal axis of said burner;
• (4) simultaneously passing a separate feedstream of free-oxygen containing gas with or without mixture with a separate feedstream of steam through the central conduit in said burner;
• (5) mixing together said reactant streams from (3) and (4) in said pre-mix zone to produce a well-distributed, mixture and reacting said mixture by partial oxidation in the reaction zone of said gas generator at an autogenous temperature in the range of about 1700.degree. to 3500.degree., a pressure in the range of about 1 to 300 atmospheres, an atomic ratio of oxygen/carbon in the range of about 0.5 to 1.7, and a weight ratio H.sub.2 O/fuel in the range of about 0.1 to 3.0;
• (6) replacing in said annular passage said feedstream of principal fuel with a replacement feedstream of stand-by fuel by phasing out of the fluid passage means in which it is flowing said stream of principal fuel, said phasing out being with a uniformly decreasing rate of flow that varies from maximum to 0 over a period of time in the range of about 1-3600 seconds;
• and simultaneously phasing said stream of stand-by fuel into the same fluid passage at a uniformly increasing rate of flow that varies from 0 to maximum rate over the same period of time and mixing with the remaining portion of and replacing the phased out portion of said stream of principal fuel;
• and simultaneously with or after the completion of said replacement of feedstreams;
• (7) adjusting the flow rate of the feedstream of free-oxygen containing gas passing through the burner, and if necessary introducing supplemental H.sub.2 O into the reaction zone so as to adjust the free oxygen/carbon atomic ratio and the weight ratio H.sub.2 O/fuel in the reaction zone to design conditions for the partial oxidation reaction.