Exothermic reaction, system for supplying a reactant gas and a shielding fluid to a reactor, and control signal generating circuit for use in said system

A control signal generating circuit for use in a system for supplying a reactant gas and a shielding fluid to a reactor having a refractory lining, and a plurality of annular nozzles mounted in said lining each of said nozzles having an inner reactant gas passage and an annular shielding fluid passage surrounding said reactant gas passage, which system comprises:

• a reactant gas manifold and a plurality of reactant gas feed conduits connected to said reactant gas manifold and adapted to be connected to respective ones of said reactant gas passages,
• a shielding fluid manifold and a plurality of shielding fluid feed conduits connected to said shielding fluid manifold and adapted to be connected to respective ones of said shielding fluid passages,
• a reactant gas pressure sensor for sensing the pressure in said reactant gas manifold, and
• a control system for controlling the fluid in said shielding flow feed conduits
• said control system comprising for each of said shielding fluid feed conduits a control valve for controlling the flow in the associated shielding fluid feed conduit and an actuator adapted to receive an actuator control signal and to control the flow area of the control valve for the same shielding fluid feed conduit in a predetermined relation to the magnitude of said control signal,
• said control signal generating circuit comprising for each of said shielding fluid feed conduits a pressure sensor for sensing the pressure in the associated shielding fluid feed conduit and a pressure controller, which has a reference input operatively connected to said reactant gas pressure sensor and a second input connected to the shielding gas pressure sensor for the same shielding fluid feed conduit, said pressure controller being adapted to generate a pressure control signal in dependence on said pressure in said reactant gas manifold and the pressure in the associated shielding fluid feed conduit,
• said control signal generating circuit further comprising a reactant gas flow rate sensor for sensing the flow rate in said reactant gas manifold, and, for each of said shielding fluid feed conduits, a shielding fluid flow rate sensor for sensing the flow rate in the associated shielding fluid feed conduit, and a flow rate controller, which has a reference input operatively connected to said reactant gas flow rate sensor and a second input operatively connected to said shielding fluid flow rate sensor for the same shielding gas feed conduit, each of said flow rate controllers being adapted to generate a flow rate control signal in dependence on said flow rate in said reactant gas manifold and on said flow rate in the associated shielding fluid feed conduits, and
• said control signal generating circuit comprising for each of said shielding fluid feed conduits
• a comparator adapted to receive said pressure control signal and said flow rate control signal from the pressure and flow rate controllers for the same shielding fluid feed conduit and to deliver to the actuator for the same shielding fluid feed conduit as an actuator control signal only that one of said flow rate and pressure control signals which corresponds to a smaller flow area of the associated control valve.