Abstract: Systems and apparatuses for neutralizing acidic compounds in flue gases emitted from a heat recovery coke oven. A representative system includes a spray dry absorber having a barrel that includes a plurality of wall plates that form sidewalls of the barrel. The wall plates include a steel plate and a corrosion resistant alloy cladded to the steel plate and the wall plates are oriented such that the corrosion resistant alloy faces toward and is in fluid communication with an interior area of the barrel. The alloy is resistant to corrosion caused by the acidic compounds in the flue gas and can prevent the steel plate from being corroded by these acidic compounds.

Abstract: The invention relates to a method for sintering carbon bodies (16) in a furnace comprising at least a first furnace chamber (11) for receiving the carbon bodies, which are accommodated in a packing material (23), the carbon bodies being arranged between lateral chamber walls (12, 13, 21) of the furnace chamber, and the furnace chamber serving to form a preheating zone V, a heating zone H provided with a heating device, and a cooling zone A, wherein a packing material (23) made, at least in part, of a highly heat-conductive material is used.

Abstract: Disclosed is a process for controlling injection of magnesium oxide (or precursor) for reducing the concentration of sulfur trioxide in combustion gases from a combustor burning vanadium and sulfur-containing fuel while operating the boiler with enhanced efficiency. In-fuel introduction is combined with mid-temperature introduction, where both can be operated effectively, are found to be of primary importance. When in-fuel introduction will not be effective due to selectivity problems, feed can be shifted to a high-temperature zone. Where the high- or mid-temperature zone cannot be fully utilized due to obstructions for injection or insufficient soot blowers to address fouling of that zone or boiler operational changes to integrate the magnesium oxide injection is insufficient, an entire or a portion of feed can be shifted to the low-temperature zones.

Abstract: A dross processing system crucible comprising a substantially vertical inner wall having an upper end, a lower end, an outer surface, and an inner surface, a bottom having an upper surface and a lower surface, the upper surface affixed to the lower end of the inner wall. A blockable port is disposed in the bottom, and a thermal insulating material covers the outer surface of the vertical inner wall and the lower surface of the bottom. An outer vessel is affixed to the upper end of the substantially vertical inner wall, and the thermal insulating material is disposed between the outer surface of the inner wall and the outer vessel.

Abstract: A flue gas treatment apparatus for removing sulfur contents contained in combustion flue gas, includes a treatment agent feeder to feed a treatment agent into a flue through which the combustion flue gas flows, a cooler to cool the combustion flue gas to which the treatment agent has been fed and condense SO3 components in the combustion flue gas, an electric dust collection apparatus provided in the flue, a desulfurization apparatus based on a lime-gypsum process, and a circulation line for feeding a portion of the dust particles recovered by the electric dust collection apparatus into the flue that is provided on an upstream side of the cooler in the direction of flow of the flue gas for circulated use thereof as the treatment agent.

Abstract: A flue gas reheater, including: a heat absorption section; a first heat release section; a second heat release section; a control system; circulation pipes; a flow control valve; and temperature sensors. The first heat release section and the second heat release section are connected to the heat absorption section via the circulation pipes. A heat transfer medium is disposed inside the circulation pipes. The circulation pipes include ascending pipes and descending pipes connecting the heat absorption section to the first heat release section and the second heat release section. The flow control valve is disposed on a condensate pipeline entering the second heat release section. The temperature sensors are disposed in the first heat release section and the heat absorption section. The flow control valve and the temperature sensors are all connected to the control system.

Abstract: The invention relates to quaternary ammonium amide and/or ester salts and their use as additives, including their use in fuels, such as diesel fuel. The invention particularly relates to the use of quaternary ammonium amide and/or ester salts as detergents in diesel fuels.

Abstract: There is provided a process for operating a coal-fired furnace to generate heat. The process has the steps of a) providing the coal to the furnace and b) combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace. The first slag-reducing ingredient and the second slag-reducing ingredient are different substances. The first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and combinations thereof. The second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, and ammonium phosphate. There is also provided a method for reducing slag formation in a coal-fired furnace.

Abstract: An intelligently controlled catalytic converter automatically monitors various operating parameters, such as water jacket temperature, catalytic input temperature, catalytic converter output temperature, oxygen level, ambient temperature, ambient humidity and/or ambient barometric air pressure, of a biofuel-fired device and automatically controls dampers, blowers and electric heaters in the device.

Abstract: There is provided a process for operating a coal-fired furnace to generate heat. The process has the steps of a) providing the coal to the furnace and b) combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace. The first slag-reducing ingredient and the second slag-reducing ingredient are different substances. The first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and combinations thereof. The second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, and ammonium phosphate. There is also provided a method for reducing slag formation in a coal-fired furnace.

Abstract: An apparatus and method is presented for removing acid gases and other trace contaminants to very low levels in combustible gases generated from thermal gasification of biomass or refuse-derived fuels. The invention includes optimization of geometric variables, temperature and pressure set points via use of a pressurized bubbling fluidized bed reactor to convert granular raw (non-activated) sorbents and auto-generated biochar sorbents) into activated, highly dispersed, and ideally sized particles for removing acid gases and toxic metals. The system can incorporate a generated gas cooler, a gas-sorbent contact chamber or zone, and a novel filter (with or without additional gas cooling and residence time stages).

Abstract: A method of operating a thermal installation other than a gas turbine and use of such a method for inhibiting vanadic corrosion is disclosed herein. Embodiments of the invention relate to a method of operating a thermal installation comprising a combustion chamber fed with a fuel contaminated with vanadium, with sulfur and possibly with sodium. The combustion chamber is also fed with boron and with magnesium, in quantities such that the magnesium molar ratio m=MgO/V2O5 and the boron molar ratio b=B2O3/V2O5 satisfy the conditions (i) m?2+b; (ii) m?3+2b; (iii) b?0.5 and (iv) b?2, so that the combustion products comprise magnesium vanadate, mixed magnesium boron oxide and possibly sodium borate.

Abstract: A method and device for cooling hot crude gas and slag from entrained flow gasification of liquid and solid combustibles at crude gas temperatures ranging from 1,200 to 1,800° C. and at pressures of up to 80 bar in a cooling chamber disposed downstream of the gasification reactor by injecting water. The cooling water is distributed, with a first portion being finely dispersed into to cooling chamber and a second portion being fed at the bottom into an annular gap provided between the pressure-carrying tank wall and an incorporated metal apron for protecting said pressure-carrying tank wall. The second portion of the cooling water flows upward in the annular gap and trickles down the inner side of the metal apron in the form of a water film.

Abstract: A slag and corrosion control process is described. The process entails: identifying the location of at least one slagging problem area in a boiler; introducing a slag control chemical comprising magnesium oxide or hydroxide into combustion gases in a location identified as having a slagging problem; identifying the location of at least one corrosion problem area in a boiler; and introducing a corrosion control chemical comprising a sulfate salt, bisulfite salt, sulfuric acid, or sulfur into combustion gases in a location identified as having a corrosion problem. In operation, these slag deposits will be sufficiently friable to be removed by relatively moderate application of physical energy, thus saving time and reducing any damage to the tubes by the cleaning process. The slag deposits are less voluminous and less in weight and are removed quickly. It is an advantage of the invention that slag can be removed with little or no shut down of a boiler.

Abstract: The invention provides a method of operating a thermal installation comprising a combustion chamber fed with a fuel contaminated with vanadium, with sulphur and possibly with sodium. In particular, the combustion chamber is also fed with boron and with magnesium, in quantities such that the sodium molar ratio s=Na2SO4/V2O5, the magnesium molar ratio m=MgO/V2O5 and the boron molar ratio b=B2O3/V2O5 satisfy the equation m?3+2b?s, so that the combustion products comprise magnesium orthovanadate, mixed magnesium boron oxide and possibly sodium borate. The invention also provides for the use of such a method to inhibit corrosion of the thermal installation by vanadium oxide, possibly in the presence of sodium.

Abstract: A process for improving the operation of combustors includes the steps of burning a carbonaceous fuel in a combustor system and determining combustion conditions within the combustor system that can benefit from a targeted treatment additive, wherein the determinations are made by calculation including computational fluid dynamics and observation. The process further includes locating introduction points in the combustor system where introduction of the targeted treatment additive could be accomplished. Based on the previous steps, a treatment regimen for introducing the targeted treatment additive to locations within the combustor system results in one or more benefits selected from the group consisting of reducing the opacity of plume, improving combustion, reducing slag, reducing LOI and/or unburned carbon, reducing corrosion, and improving electrostatic precipitator performance. The targeted treatment additive comprises an alloy represented by the following generic formula (Aa)n(Bb)n(Cc)n(Dd)n(. . .

Abstract: This invention improves gas mixing and combustion, gaseous fluid flow and control of the char bed in recovery boilers burning black liquor or soda liquor, requires fewer primary air ports than conventional methods and can reduce capital and operating costs. Some primary air is introduced as powerful principal jets, from two opposing so-called active furnace walls. All or most of the remainder of the primary air is introduced as smaller jets, called scavenging jets, which prevent char from accumulating in the furnace corners and, in some cases, between the principal jets and are in the same plane as the principal jets. The momentum flux of each of the principal jets is approximately double or more than double that of each scavenging jet. Some of the primary air may be introduced as central jets, from the remaining two furnace walls and located in the same plane as the other ports, or on a second, somewhat higher plane. The momentum flux of the central jets is less than that of the principal jets.

Abstract: Disclosed is a process that increases the output of a combustor fired with coal having high iron and/or calcium content, by reducing the tendency of slag to form on heat exchange surfaces and changing the nature of the slag to make it easier to remove. The process includes combusting a slag-forming coal, having high iron and/or calcium content, with an overall excess of oxygen; moving the resulting combustion gases though heat exchange equipment under conditions which cause cooling of slag formed by burning the fuel; and prior to contact with said heat exchange equipment, introducing aqueous aluminum trihydroxide in amounts and with droplet sizes and concentrations effective to decrease the rate of fouling, and preferably, increase the friability of the resulting slag.

Abstract: A plant (100) includes a gas turbine (110) that receives a feed gas (130), wherein a metal plates from a metal carbonyl contained in the feed gas onto a sacrificial metal (152A) in an adsorber (150A), and wherein the feed gas in the adsorber has a temperature sufficient for plating the metal onto the sacrificial metal.

Abstract: There is provided a process for operating a coal-fired furnace to generate heat. The process has the steps of a) providing the coal to the furnace and b) combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace. The first slag-reducing ingredient and the second slag-reducing ingredient are different substances. The first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and combinations thereof. The second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, and ammonium phosphate. There is also provided a method for reducing slag formation in a coal-fired furnace.

Abstract: This invention relates to a boiler (1) drying, igniting and combusting refuse and producing steam (2, 2a) by heat exchange with flue gases (3), said boiler defining a main flow direction (5) of gases, said boiler (1) comprising a separator element (4) and an end superheater (8), the separator element (4) being adapted for separating said flue gases (3) into streams of a less-corrosive gas flow (6) and a corrosive gas flow (7), said separator element (4) being located substantially in and along said main flow direction (5), said end superheater (8) being located in proximity to said separator element (4) and in the flow (6) of said less-corrosive gas. Said separator element (4) comprises a plate (4a) or a wall (4b), which in a number of said separator elements (4) forms a channel as another separator element. This provides for an increased lifetime of said superheater and makes the boiler provide a high and efficient electrical power output.

Abstract: A system and a method for decreasing a rate of slag formation at predetermined locations in a boiler system are provided. The boiler system has a plurality of burners, a plurality of slag detection sensors, a plurality of temperature sensors and a plurality of CO sensors disposed therein. The system determines locations within the boiler system that have relatively high slag thickness levels utilizing the plurality of slag detection sensors and then adjusts A/F ratios or mass flows of burners affecting those locations, or adds slag reducing additives to the burners affecting those locations, to decrease a rate of slag formation at the locations, utilizing signals from the plurality of slag detection sensor, the plurality of temperature sensors, and the plurality of CO sensors.

Abstract: A glassmelting furnace is heated by combustion of fuel having an atomic ratio of hydrogen to carbon of 0.9 or less.

Abstract: A staged-coal injection procedure for coal-fired boilers used in power generation. The procedure includes the steps of combusting a first type of coal in a first zone of a furnace; and combusting a second type of coal in a second zone of the furnace. The second zone is at a position separate from the first zone.

Abstract: A process for mitigation of fouling deposits within a combustion zone, capturing of toxic metal emissions, and reduction of visible sulfur emissions attributable to sulfuric acid mist during coal combustion. SO3 formed during coal combustion is reduced by the addition to the coal of raw, unprocessed magnesium-containing minerals such as magnesite ore or brucite ore. The minerals are pulverized to a fine particle size and combined with pulverized coal to provide a mixture of the particles. The mixture is combusted and the ore particles calcine and decrepitate to very fine magnesium oxide particles that have a significant particle surface area. The magnesium oxide particles react with the SO3 produced during combustion of the coal and also capture toxic metals to reduce the quantity of undesirable stack discharge components.

Abstract: A process for controlling both fireside ash deposits and corrosion, and fouling, corrosion, and emissions due to SO3 formation within a fossil-fuel-fired combustion system, such as a furnace forming part of an electrical power generating plant. A solution of a soluble magnesium compound, which can be derived from wastes, such as the bleed stream from the power plant's SO2 scrubber, is injected into the combustion products within the furnace in the form of a fine spray and at a point at which the temperature is sufficiently high to produce submicron-size MgO particles. The SO3 reacts with the MgO particles to form MgSO4. Insoluble magnesium compounds can be added to the solution to produce larger (micron sized) MgO particles on thermal decomposition. The micron-sized MgO particles are deposited on furnace surfaces to reduce ash deposits and to reduce catalytic generation of SO3. The boiler wastes can be reacted with other industrial process waste products to provide marketable chemicals.

Abstract: The present invention provides a process for the control of a cleaning system for a boiler which incorporates factors related to the overall operation and efficiency of the boiler. Current values of plant data parameters associated with the boiler furnace are compared with respective setpoint values. The process then determines if the furnace is to be cleaned based on this comparison.

Abstract: In a fluid bed apparatus in which a layer of pulverulent or particulate material is fluidized by means of fluidizing gas which is introduced through openings in a bed plate in a first plurality of streams of flows of gas, means are provided for introducing a second plurality of streams of flows of gas at a site or sites of introduction and is directed from said site or sites along the surfaces of at least some of the walls of the housing to form a gas barrier covering at least a substantial part of said wall surfaces and the ceiling of the housing thus reducing detrimental effects, in particular deposition of products, condensation and corrosion, on the surfaces of the walls and ceiling of the housing.

Abstract: The present invention is a method for reducing the slagging and fouling of the surfaces of the waterwalls, firebox, superheater, and reheater of the furnace of a coal-fired steam boiler. The process reduces the firebox exit temperature to below the specific ash melting temperature by injecting the following, either alone or in combination, into ports located in the upper section of the firebox: recirculated flue gas from downstream of the electrostatic precipitator, atomized water, or a sorbent water slurry. All of these materials have a lower temperature than the main flue gas or require additional heat for evaporation. Mixing these materials with the main flue gas from the furnace will not affect the coal combustion process, yet will reduce the temperature of any fly ash particles in the main flue gas to below the specific ash fusion temperature, and thus, prevent slagging and fouling within the furnace.

Abstract: In a method of measuring heat flux and corrosion in a furnace, pairs of thermocouples are attached to the back side of the furnace wall. One thermocouple of each pair is attached to a tube and the second thermocouple is attached to a web connected to that tube. A temperature differential is determined for each pair at selected time intervals. A decrease in the difference between temperature differentials indicates slag on the furnace wall has melted indicating corrosion can be occurring.

Abstract: A method for protecting a SiO2 coating on defining surfaces of a combustion chamber and a combustion device containing the protection. Accordingly, an additive is introduced into the combustion chamber, which increases the SiO content of the exhaust gas, arising from a combustion process. The SiO content helps protect walls of the combustion chamber formed with the SiO2 coating.

Abstract: A method for minimizing corrosion and the build-up of deposits on surfaces of a flue-gas system exposed to moist substances and elevated temperatures, and particularly those surfaces which are used to convey other additives to the system and the surfaces of gas/gas heaters which receive the output from scrubbers, which method involves adding to the system, particularly in those conduits and at the surfaces of the gas/gas heater, generally inert bulking agents such as perlite and vermiculite in expanded form, such agents, apparently by acting under the operating conditions to which they are subjected to retain substantial quantities of water without becoming dissolved, accomplishing the desired results.

Abstract: The present invention relates to a method for reducing agglomeration, sintering and deposit formation resulting from the gasification or combustion of a solid carbonaceous fuel material comprising a combustible portion and a non combustible inorganic portion, which non combustible inorganic portion comprises 4 to 50 parts by weight of Kw+Naw, and 0 to 40 parts by weight of Siw, wherein Kw is potassium, Naw is sodium, and Siw is silicon, all calculated in parts by weight of the elements per 100 parts by weight of the inorganic portion, and optionally also chloride, phosphorus, calcium and sulphur which method is characterised in adding to the fuel before or during the gasification or combustion, Padded parts by weight of phosphorus compound calculated as P wherein the amount Padded is calculated in accordance with the formula I Padded=q1×(31/39 Kw+31/23 Naw−Pw−31/35,4 Clw)  (I) wherein q1=0.

Abstract: While silicon-containing ceramics or ceramic composites are prone to material loss in combustion gas environments, this invention introduces a method to prevent or greatly reduce the thickness loss by injecting directly an effective amount, generally in the part per million level, of silicon or silicon-containing compounds into the combustion gases.

Abstract: A method for minimizing corrosion and the build-up of deposits on surfaces of a flue-gas system exposed to moist substances and elevated temperatures, and particularly those surfaces which are used to convey other additives to the system and the surfaces of gas/gas heaters which receive the output from scrubbers, which method involves adding to the system, particularly in those conduits and at the surfaces of the gas/gas heater, generally inert bulking agents such as perlite and vermiculite in expanded form, such agents, apparently by acting under the operating conditions to which they are subjected to retain substantial quantities of water without becoming dissolved, accomplishing the desired results.

Abstract: A method for monitoring and reducing corrosion in furnace boiler tubes measures electrochemical noise associated with corrosion mechanisms while corrosion is occurring at the surface of the tubes as they are exposed to combustion products. This noise is detected using a probe at the boiler waterwall surface that is connected to a corrosion monitor. The monitor contains a computer and software which determines a corrosion rate from the measured electrochemical noise. That rate is compared to a standard to determine if the rate is within acceptable limits. If not, the operator of the furnace or an Adaptive Process Controller (APC) is notified and adjusts one or more burners to change the combustion products that are responsible for the corrosion. Such an adjustment could be made by changing the amount of air or fuel being provided to the burner or other air slots or air ports.

Abstract: A method for preventing corrosion of a furnace by a corrosive gas. The material for the bottom tray in the furnace is made of anti-corrosion alloy such as molybdenum and chromium. The furnace also has an oxygen-containing gas pipe for charging the oxygen-containing gas. The oxygen-containing gas is reacted in a high temperature to form a purple oxide alloy film on the surface of the alloy tray.

Abstract: In an improved system for recovering heat from a combustion gas produced by burning wastes, the combustion gas or combustible gas produced by partial burning of the wastes subjected to dust filtration in a temperature range of 450-650° C. at a filtration velocity of 1-5 cm/sec under a pressure of from −5 kPa (gage) to 5 MPa before heat recovery is effected. The dust filtration is preferably performed using a filter medium which may or may not support a denitration catalyst. Heat recovery is preferably effected using a steam superheater. The dust-free gas may partly or wholly be reburnt with or without an auxiliary fuel to a sufficiently high temperature to permit heat recovery. The combustion furnace may be a gasifying furnace which, in turn, may be combined with a melting furnace.

Abstract: A method and apparatus for reducing NOx emissions in a furnace having a main combustion zone with a waterwall and apparatus for supplying main combustion air and fuel to the main combustion zone, also reduces unburned carbon and waterwall corrosion in the furnace. The method involves providing at least one lower overfire air injector at a first level over the main combustion zone of the furnace for supplying overfire air to create a lower overfire air zone in the furnace over the main combustion zone and at least one upper overfire air injector at a second level over the lower overfire zone for supplying overfire air to create an upper overfire air zone in the furnace over the lower overfire zone. The overfire air in the lower and upper overfire air zones are supplied at a rate for reducing the stoichiometry in the main combustion zone which reduces unburned carbon and a corrosive reducing atmosphere in the furnace.

Abstract: This invention improves fluid flow, gas mixing and combustion in the furnaces of recovery boilers which burn liquor from various pulping processes, namely, the kraft process, the soda process, the sodium-based sulphite process, the closed-cycle CTMP (chemical, thermal, mechanical pulp) process, the magnesium-based sulphite process and the ammonium-based sulphite process, which are employed in the manufacture of pulp and paper, and in the furnaces of boilers burning biomass, wood waste or other solid fuel. The invention improves the operation of new or retrofitted boilers in several ways and can reduce both the capital and operating costs. One embodiment comprises introducing a portion of the combustion air, and/or recycled flue gas, at any elevation in the furnace, from two opposing walls only, as jets arranged in a partially-interlaced manner, with the jets oriented in a more or less common plane which is inclined.

Abstract: In an improved system for recovering heat from a combustion gas produced by burning wastes, the combustion gas or combustible gas produced by partial burning of the wastes subjected to dust filtration in a temperature range of 450-650° C. at a filtration velocity of 1-5 cm/sec under a pressure of from −5 kPa (gage) to 5 MPa before heat recovery is effected. The dust filtration is preferably performed using a filter medium which may or may not support a denitration catalyst. Heat recovery is preferably effected using a steam superheater. The dust-free gas may partly or wholly be reburnt with or without an auxiliary fuel to a sufficiently high temperature to permit heat recovery. The combustion furnace may be a gasifying furnace which, in turn, may be combined with a melting furnace.

Abstract: In an improved system for recovering heat from a combustion gas produced by burning wastes, the combustion gas or combustible gas produced by partial burning of the wastes subjected to dust filtration in a temperature range of 450-650° C. at a filtration velocity of 1-5 cm/sec under a pressure of from −5 kPa (gage) to 5 MPa before heat recovery is effected. The dust filtration is preferably performed using a filter medium which may or may not support a denitration catalyst. Heat recovery is preferably effected using a steam superheater. The dust-free gas may partly or wholly be reburnt with or without an auxiliary fuel to a sufficiently high temperature to permit heat recovery. The combustion furnace may be a gasifying furnace which, in turn, may be combined with a melting furnace.

Abstract: A method of and apparatus for decreasing attack of detrimental components of solid particle suspensions on heat transfer surfaces in a heat transfer chamber in a fluidized bed reactor. The method includes introducing solid particles into a first chamber, which is a dilution chamber, on top of a bed of solid particles therein through a dilution chamber inlet disposed in an upper part of the dilution chamber, and discharging solid particles from the dilution chamber through an outlet disposed in a lower part of the dilution chamber, into a heat transfer chamber, and introducing a flushing gas into at least a portion of the dilution chamber for performing at least one of inactivating in and separating from the bed of solid particles in the dilution chamber, impurities detrimental to heat transfer surfaces in the heat transfer chamber.

Abstract: The invention relates to a steam generator (1) for superheated steam for incineration plants with corrosive flue gases, essentially comprising a radiation section (2) and a convection section (5), having at least one superheater (8) and having plates (10) arranged on the inside of at least one wall (9) of the radiation section (2), a space (12) being provided between the plates (10) and the wall (9) of the radiation section (2), and at least part of the superheater (8) being arranged as a wall superheater (15) in the space (12) in the radiation section (2). The steam generator is distinguished by the fact that the space (12) contains a noncorrosive gaseous atmosphere which is at a higher pressure than the pressure of the gases in the combustion chamber (3). In this way, it is possible to reach a high superheater temperature without corrosion to the final superheater, so that the superheater can be made from inexpensive material.

Abstract: An air nozzle for introducing secondary air into a furnace and including a housing provided with an inlet at one end thereof for receiving air and an outlet at the other end thereof for discharging the air. A damper is disposed in the housing in the path of the air for splitting the flow of the air into two flow streams which extend to different areas of the furnace and is adapted for pivotal movement in the housing to vary the amount of air flow in each of the streams and the discharge angle of one of the streams.

Abstract: A combustion method in which a coal/primary air mixture is discharged from burners located in the corners of the furnace towards an imaginary circle disposed in the center of the furnace. Air is discharged from air nozzles also located in the corners of the furnace in two flow streams--one directed towards the center of the furnace in a combustion-supporting relation to the fuel, and the other along the inner surfaces of the furnace boundary walls to maintain an oxidizing atmosphere and minimize corrosion and slagging.

Abstract: A method to reduce waterwall corrosion in a low NO.sub.x boiler includes the steps of locating a waterwall area of a low NO.sub.x boiler where oxidizing conditions exist and deposition of FeS is likely. The combustion air input at the waterwall area is biased to reduce FeS deposition on the waterwall. The biased combustion air input increases the oxidation rate of FeS.sub.2 so as to reduce FeS deposition on the waterwall. The biased combustion air input may be achieved by increasing the air-to-fuel ratio of one burner while reducing the air-to-fuel ratio of another burner, such that the overall air-to-fuel ratio in the low NO.sub.x boiler is substantially constant.

Abstract: A method and apparatus for extending the life of air ports and nozzles in furnaces, particularly recovery boilers for burning black liquor to produce heat and a chemical melt. Apparatus is provided for feeding combustion air into a furnace having a tube wall, the apparatus comprising: an air port disposed in the tube wall, and connected to an air duct through which air flows into and then through the air port, and into the furnace; and a protective insert of heat conductive and heat and corrosion resistant material mounted in the air port and positioned so that it is cooled by the air flowing through the air port. The protective insert has sufficient thermal mass (e.g. a volume of between 40,000-4,000,000 cubic mm) so as to effectively even out temperature peaks caused by melt splashes from the furnace impacting the vicinity of the air port, e. g. the protective insert is made out of highly corrosion resistant steel such as stainless steel.

Abstract: In an improved system for recovering heat from a combustion gas produced by burning wastes, the combustion gas or combustible gas produced by partial burning of the wastes subjected to dust filtration in a temperature range of 450-650.degree. C. at a filtration velocity of 1-5 cm/sec under a pressure of from -5 kPa (gage) to 5 MPa before heat recovery is effected. The dust filtration is preferably performed using a filter medium which may or may not support a denitration catalyst. Heat recovery is preferably effected using a steam superheater. The dust-free gas may partly or wholly be reburnt with or without an auxiliary fuel to a sufficiently high temperature to permit heat recovery. The combustion furnace may be a gasifying furnace which, in turn, may be combined with a melting furnace.

Abstract: Reduction of slagging is improved by targeting slag-reducing chemicals in a furnace with the aid of computational fluid dynamic modeling. Chemical utilization and boiler maintenance are improved.