Furnaces – Process – Burning pulverized fuel
Reexamination Certificate
1999-07-02
2001-04-17
Lazarus, Ira S. (Department: 3743)
Furnaces
Process
Burning pulverized fuel
C110S262000, C110S263000, C110S342000
Reexamination Certificate
active
06216613
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a coal combustor and, more specifically, will be referred to as an entropic reactor for the combustion of coal in fossil burning plants, such as utility plants.
BACKGROUND ART
Most fossil burning plants, such as utility plants, presently utilize a burning or firing combustion process in which most of the thermochemical reaction takes place beyond the burner duct port in the furnace work chamber. Further oxidation of the unburned fuel particles exiting the burner is termed “residual-combustion” and equates to a degree of inefficiency. The negative resultant aspects following initial combustion in the burner effects the reformulation of unburned hydrocarbons having a higher ratio of carbon to hydrogen, an added detriment to the further completion of combustion. In order to finalize combustion, excessive amounts of combustion air must be introduced into the work chamber and various methods of under/over firing with gaseous fuels must be utilized to effect “reburn.” This results in over-voluminous, inefficient and high cost boiler structures.
Past attempts by various firms knowledgeable in the art of thermochemical combustion to develop a combustor designed to complete all oxidizing rate-reactions have failed. During the 1980s the DOE funded millions of dollars to such projects. Operationally, the then designed combustors thermochemically failed to totally oxidize the carbonic elements. This resulted in a graphitic “char” formation causing clogging and eventual shutdown of the process.
Present firing combustion processes also exhibit post combustion problems which adversely affect the environment. Pollutants formed by sulfurous compounds and nitrous oxides and particulates, unless treated by expensive control systems, typically result from presently utilized combustion processes. A more advanced thermotechnical method for the oxidative combustion of hydrocarbons is desirable in order to eliminate or reduce problems associated with these pollutants.
DISCLOSURE OF THE INVENTION
The present invention provides a new and improved thermotechnology for the design of a combustor for use in, for example, steam generation in the boiler of a utility power plant. The disclosed Entropic Reactor-Combustor (ER-C) structure includes a reactor chamber, combustion chamber, and discharge chamber serially connected along a central axis.
In one preferred embodiment, the structure is formed as a single-cell entropic-reactor combustor (ER-C). In this embodiment, each chamber is made of a high temperature and corrosion resistant material such as a refractory/ceramic material. These refractory chambers define, respectively, a reactor zone, combustion zone, and discharge zone that extend through the refractory.
According to an illustrated embodiment of the invention, the combustion chamber comprises a venturi and the discharge chamber comprises a diverging nozzle. The single-cell ER-C includes a ceramic baffle insert that is concentrically disposed within the forward end of the reactor chamber. According to the invention, the baffle defines at least one coal-gas passage extending longitudinally through the baffle and includes means for communicating an air-fuel mixture to the reactor zone. A reactor core tube, made of a refractory material, is sealingly engaged by the baffle. The core of the tube is in fluid communication with the coal-gas passage. The tube extends longitudinally through a portion of the reactor zone and terminates into the combustion zone. The reactor core tube communicates a coal-gas mixture from the coal-gas passage to the combustion zone. Means are provided for burning the air-fuel mixture in the reactor zone thereby heating the reactor core tube. The coal-gas mixture passing through the reactor core tube is thereby heated by conduction through the tube before entry into the combustion zone.
By irradiating the coal-gas mixture with heat energy the volumetric specific heat of the mixture is substantially raised. It is believed that this irradiation (which may be termed photolytic irradiation) ionizes the coal molecule and causes a debonding of its molecular structure. A molecular reformation of the coal and gas takes place that creates a new fuel mixture before the mixture is discharged from the reactor core tube. This restructuring of the coal-gas mixture effects a more effective and efficient burning upon combustion in the combustion chamber so that carbon by-products or graphitic build-up in the work chamber is substantially reduced or eliminated.
According to a feature of the invention, the air fuel mixture is communicated by means of an array of fuel burner ducts spaced from and disposed around the coal-gas passage, and extending longitudinally through the ceramic baffle insert. Disposed around each fuel burner duct is an array of air supply ducts extending longitudinally through the ceramic baffle insert.
According to another feature of the invention, the combustion chamber includes a plurality combustion air supply pipes extending radially through the chamber and terminating into the combustion zone. The air supply pipes are equally spaced apart around the periphery of the combustion chamber. There are an even quantity of air supply pipes so that any pipe in the array is diagonally opposed from another pipe in the array.
In another preferred embodiment, the entropic reactor combustor (ER-C) comprises a plurality of cells that are used to achieve the desired amount of volumetric specific heat. The design of the reactor chamber is based on an array of planetarily positioned unitized cells. The reactor chamber comprises a ceramic baffle in concentric relation to the reactor core chamber. Extending longitudinally through the baffle, and spaced a distance from the reactor core center, is a first array of integrated ceramic entropic fuel tubes, or ducts, disposed on a first inner radius and a second array of relatively larger ceramic tubes, or ducts, disposed on a larger second radius. Interposed between the first and second radially disposed ducts is an array of corresponding cavity ducts, or gaps, which form a series of interspacial reactor core cells, or a continuous planetary circumferential reactor chamber.
A fuel mixture, such as pulverized coal and methane gas, is dispensed into the interspacial reactor core chamber cells through a series of pulverized coal/gas supply nozzles attached to the ends of the reactor core chamber cells. An entropic fuel, such as methane gas, and combustion air are combined in the first and second array of entropic fuel ducts through a series of air/gas mix supply nozzles attached to the ends of the tubes. The air/gas mixture, when burned in the multiple series of entropic fuel ducts, generates intense heat required for conductivity through the walls of the entropic fuel ducts enclosing the interspacial reactor core chamber. The conducted source of continuous heat from the outer surface of the reactor core chamber is radiated to the inner surface of the reactor core to heat the pulverized coal/gas fuel mixture during passage through the reactor core chamber.
It is believed that in the disclosed apparatus the pulverized coal particles are initially subject to a sufficiently powerful thermalytically induced radiation to degratively decompose the molecular structure of the pulverized coal particles. The thermalytic process maximizes the entropy, and therefore, increases the internal electrostatic energy of the coal molecule. During further passage through the interspacial reactor core chamber the irradative exposure causes critical phase changes, promoting a vaporous/gaseous state. Concurrently, additional rapid operatives promoted by ionization and radicalization of the coal molecules effect requisite molecular reformations critical to subsequent detonative-oxidation of all carbonic elements of the coal particle in the downstream ER-C combustion chamber.
Unlike presently utilized conventional flame combustion devices or coal-firing systems, the ER-C thermal technology maximizes thermoflux
Ciric Ljiljana V.
Lazarus Ira S.
Theoretical Thermionics, Inc.
Watts, Hoffmann, Fisher & Heinke Co.
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