| abstract |
A mixture of fuel and air is introduced onto a catalytic combustion surface, preferably an inert, refractory substrate coated with trace amounts of a catalyst. Combustion is normally initiated by an ignition device, and proceeds spontaneously once the minimum temperature has been reached. Water is introduced directly onto the heated combustion surface, in metered quantities to prevent cooling below the desired minimum combustion temperature, thus generating a continuous flow of steam at a pressure equal to the inlet pressure of the air, fuel and water. The quantities of air, fuel and water may be varied proportionately to produce rapid variation in the volume, temperature and pressure of the steam generated, a function that may be greatly facilitated by the choice of a combustion element having a low thermal mass. Both the catalytic combustion of fuel and the vaporization of inert working fluids can occur over a wide range of temperature and pressure conditions. |