초록 ▼

In a combustion zone a fuel injector is immersed in a mixture of oxidant and products of combustion having a temperature of about 2000 degrees F. or higher. In order to maintain rapid and stable combustion, it is desirable to avoid excessive absorption of thermal energy from this mixture. To that en

In a combustion zone a fuel injector is immersed in a mixture of oxidant and products of combustion having a temperature of about 2000 degrees F. or higher. In order to maintain rapid and stable combustion, it is desirable to avoid excessive absorption of thermal energy from this mixture. To that end, the present invention provides means for impeding transfer of heat to the fuel injector from the adjacent mixture, such that portions of the mixture immediately adjacent the fuel injector may be kept at a temperature of approximately the ash-fusion temperature of the fuel, or higher, while the interior of the fuel injector is kept at a temperature substantially below the ash-fusion temperature. This means for impeding heat transfer preferably comprises at least one material having a thermal conductivity substantially lower than that of the fuel injector and, in a preferred embodiment, consists essentially of slag formed from noncombustible-mineral constituents of the fuel.

대표청구항 ▼

In an apparatus for the combustion of pulverized-coal fuel in a combustion zone and separation of the noncombustible-minerals content of the fuel from the gaseous products of combustion as slag, wherein the combustion zone is enclosed within a substantially cylindrical, water-cooled combustion chamb

In an apparatus for the combustion of pulverized-coal fuel in a combustion zone and separation of the noncombustible-minerals content of the fuel from the gaseous products of combustion as slag, wherein the combustion zone is enclosed within a substantially cylindrical, water-cooled combustion chamber having its walls at temperatures such that a layer of slag is maintained on the inside surfaces of the walls, and wherein oxidant is injected substantially tangentially into said chamber adjacent said inside surfaces in a manner to establish high velocity swirling flow of oxidant, slag droplets, fuel particles and products of combustion within said combustion zone, and wherein a fuel injector for introducing pulverized coal entrained in a flow of carrier fluid extends a substantial distance into said combustion zone substantially along the center line of said chamber and is there immersed in a mixture of oxidant, slag droplets, fuel, and products of combustion, and wherein the fuel input rate relative to the oxidant input rate is regulated in a manner to provide flow velocities and combustion temperatures of about 2000°F. or higher, so that the carbon contained in the fuel is oxidized before the fuel particles reach the walls of the chamber and substantially all of the noncombustible minerals present in the fuel are fused and deposited as liquid slag, and wherein it is desirable to maintain said fuel injector at lower temperatures in order to avoid agglutination of fuel particles and clogging of the injector and wherein substantial cooling of the gaseous mixture immediately adjacent the fuel injector would tend to inhibit combustion of the fuel closely adjacent the fuel injector, the improvement comprising: (a) a thermal-impedance sleeve peripherally enclosing at least a major portion of said fuel injector and extending within said combustion zone, for impeding the transfer of heat to the injector from the adjacent mixture of oxidant, fuel and products of combustion, said sleeve comprising first and second cylinders positioned coaxially with the second cylinder inside the first cylinder for defining an annular plenum therebetween; (b) means including at least one water-inflow conduit and at least one water-outflow conduit connected to flow water through said plenum for keeping the temperature of said injector substantially below the ash-fusion temperature of slag produced in said combustion zone; and (c) a coating of relatively high thermal-impedance material formed on and supported by the outermost one of said cylinders and serving to impede the transfer of heat to said sleeve from the gaseous mixture peripherally adjacent thereto, so that the gaseous mixture closely adjacent said sleeve may be maintained substantially at a temperature of about 2000°F. or higher for promoting rapid and stable coal combustion closely adjacent the injector.