Method and apparatus for producing heat

#This invention relates to a process and an apparatus for generating heat energy by burning carbonaceous fuels and for increasing the flame temperature in a combustion zone through the introduction of water into one or more stages of the burning process. An aspect of this invention relates to increasing the temperature output of the combustion of a known fuel with apparatus and a process capable of facilitating the in situ thermosynthesis of combustible gases having a relatively high heat of combustion. Still another aspect of this invention relates to a method for the generation of heat energy and an apparatus suitable for practicing this method, wherein combustion of liquid hydrocarbonaceous fuels is combined with the thermosynthesis of high energy gaseous fuels, and the resulting gaseous fuels are also burned to provide a high flame temperature.

#In view of the world's shrinking supply of fossil fuels, it has been proposed to find new sources of energy and to improve the efficiency of existing methods and devices for producing energy. Nevertheless, for some time to come, fossil fuels are likely to be heavily relied upon for the world's energy needs. The simplest approach to obtaining energy from a fossil fuel is to initiate its rapid oxidation (burning) in the presence of a cheap source of oxygen such as air. This approach dates back at least to ancient times, when coal fires were used to provide heat. More sophisticated approaches were used on a large scale with the advent of the industrial revolution. As early as 1972, it was proposed to manufacture gaseous fuels from oil. Since that time, a vase technology has developed relating to gasification of liquid and solid fuels.

#It has long been known that combustible gases can be synthesized from hydrocarbons, coke, and the like under various conditions. Perhaps one of the oldest examples of such a synthesis is the production of water gas from hot coke and steam by the reaction:

#FIG. 1 is a fragmentary cross-section view of a heat-generating apparatus designed to demonstrate this invention;

#FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1;

#FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1;

#As is well-known in the art of thermal energy production from carbonaceous fuels, the reaction between carbon and oxygen involves a substantial negative enthalpy change, thereby releasing thermal energy. When carbonaceous fuels are burned, this release of thermal energy is ordinarily accompanied by the formation of carbon dioxide; however, incomplete combustion products can also be formed, e.g. "soot" (which primarily comprises elemental carbon), "tar" (which comprises polymers such as polymerized hydrocarbons or oxygenated hydrocarbons), carbon monoxide, and the like. Thus, every molecule of carbon monoxide and every particle of tar or soot formed represents a loss of potentially recoverable thermal energy. By-products such as soot or carbon monoxide also present the possibility of synthesizing combustible gases through interaction with combustion products or reactants. Although this invention is not bound by any theory, it is believed that the water (preferably liquid water) introduced into the first or lower or primary reaction zone of an apparatus of this invention can assist in the formation of combustible gases, thereby creating the possibility that at least some sensible heat potential can be recovered, soot levels in the flame can be eliminated, flame temperatures can be increased, the flue gas temperatures and efflux velocities can be increased.

#As will become apparent from the following description, this invention contemplates a heat-generating process which comprises the continuous introduction of a solid or liquid fuel, oxygen, and water into a preheated first reaction zone. In its simplest aspect, this continuous introduction step involves adding the water to a continuous stream of said solid or liquid fuel and providing openings in the bottom of the first reaction zone, so that an oxygen-containing gas (preferably air) can flow in as a draft and intimately contact the said fuel and water. The result is a fuel/oxygen/water interface or mixture. The first reaction zone contains a catalytic surface comprising a transition metal, e.g. a metal from Group VIII of the Periodic Table, preferably nickel. As is known in the art of catalysis, the metallic nickel can be in plate form (as nickel or nickel alloy plate), in a finely divided form, or in the form of mixtures of nickel and kieselguhr. In the preferred practice of this invention, the catalytic surface has a vertical component, so that fuel can be caused to flow downward or pulverized fuel blown onto or along the surface. Since the surface should be preheated (e.g. preheated to a temperature well above the ignition point of carbon and/or nonvolatile hydrocarbons), it can be advantageous to introduce the said fuel along, without water, onto the catalytic surface and burn the fuel with air on this surface until the desired temperature has been reached. Then, the water can be added (e.g. added directly to the fuel), so that a fuel/water mixture flows downwardly along or blown against the said catalyst surface, and an air/fuel/water interface or mixture is provided or facilitated.

#The fuel/water/oxygen mixture or interface, particularly at temperatures well above the ignition point mentioned previously, forms hot gaseous reaction products in the presence of the catalytic surface. A portion of these gases is permitted to flow upward in a rapid stream, while some of the gases are deflected backward (i.e. upsteam, which would normally be in a downward direction). The upstream deflection of hot gaseous reaction products helps to maintain the catalytic surface at the desired temperature and to maintain any high-grade combustible gas syntheses (e.g. hydrogen or lower alkane formations) which may be occurring at or near the catalytic surface. Thus, it is ordinarily unnecessary, in the practice of this invention, to alternate air blast and steam "blow" cycles, as in the case of water gas syntheses. Furthermore, any high-grade combustible gases formed in the first reaction zone are utilized in situ within the heat-generating zone in the apparatus. Although this invention is not bound by any theory, it is believed that a portion of the freshly synthesized combustible gases is utilized in the first reaction zone, and the balance of these gases is utilized in subsequent (i.e. downstream) reaction zones, which will be described subsequently.