Abstract: A method and improved furnace for reducing nitrogen oxide emissions from a furnace having a plurality of primary fuel injectors and a plurality of spaced apart over-fire air injectors positioned above the primary fuel injectors are disclosed. Injection of over-fire air produces zones of cooler combustion gasses containing over-fire air that separate zones of hot combustion gasses containing nitrogen oxides. Reburn fuel injectors inject a reburn fuel into the zones of hot combustion making the effluent combustion gases containing nitrogen oxides partially or totally fuel-rich in order to further reduce nitric oxide.

Abstract: Methods for co-firing a fuel containing coal or oil that is injected into a burner in a furnace by injecting a gaseous fuel are disclosed. The gaseous fuel is injected in a manner so as not to consume air that would otherwise combine with the coal or oil in the primary flame. This can be accomplished by injecting the gaseous fuel at a higher or lower velocity than the coal or oil and combustion air are being injected. This can also be accomplished by directing the gaseous fuel being injected away from the primary flame created when the coal or oil burns.

Abstract: In a method of determining amounts of condensable species present in a gas containing condensable species a probe is placed into a gas containing condensable species. The probe has a plurality of spaced apart contacts on an outer non-conductive surface. That surface is heated at a selected heating rate and then cooled at a selected cooling rate over a selected time period. During that time period current flow between the contacts and the temperature of the non-conductive surface is monitored over the selected time period. Peaks in a plot of the current flow over the selected time period and the temperature for the time corresponding to each peak are then correlated to the condensable species has a kinetic dew point at each identified temperature. The identified temperature for each identified species is compared to a predetermined correlation of dew point temperature and concentration for that species to determine the concentration of that condensable species present in the gas.

Abstract: In a method of determining amounts of condensable species present in a gas containing condensable species a probe is placed into a gas containing condensable species. The probe has a plurality of spaced apart contacts on an outer non-conductive surface. That surface is heated at a selected heating rate and then cooled at a selected cooling rate over a selected time period. During that time period current flow between the contacts and the temperature of the non-conductive surface is monitored over the selected time period. Peaks in a plot of the current flow over the selected time period and the temperature for the time corresponding to each peak are then correlated to the condensable species has a kinetic dew point at each identified temperature. The identified temperature for each identified species is compared to a predetermined correlation of dew point temperature and concentration for that species to determine the concentration of that condensable species present in the gas.

Abstract: Ammonia and optionally carbon monoxide are injected into the flue gas containing metals such as mercury in a manner so that there are sufficient amounts of these materials in the flue gas when the flue gas is at a temperature of from 900° F. to 1,450° F. to oxidize the metals within the flue gas. The oxidized metals are then attracted to particulates present in the flue gas. Oxidation is facilitated by a reaction zone stabilizer through which the flue gas flows. The stabilizer provides a stable continuous ignition front. These particulates bound with oxidized metals are removed from the flue gas by a particulate removal device such as an electrostatic precipitator or baghouse. After the ammonia is injected, the flue gas can be rapidly cooled to a temperature below 500° F. to minimize decomposition of oxidized metals in the flue gas.

Abstract: In a method for removing NOx from the flue gas using a coal water slurry, other carbon containing fuel and water, or unburned carbon existing in the furnace itself due to continuing combustion, the ratio of carbon to water is adjusted so that a portion of the carbon forms activated carbon after injection of the fuel slurry into the flue gas. The activated carbon is then available to collect mercury chloride from the flue gas which has been formed through the enhancement of the mercury and chlorine oxidation reaction, enhanced through the heterogeneous reaction mechanism of this same activated carbon in the primary combustion fuel.

Abstract: In a method of removing metals such as mercury from flue gas produced by combustion devices, water or water including a calcium-containing component or water including Cl? anion formers or water including both a calcium-containing component and Cl? anion formers is injected into the flue gas in a manner so that there are sufficient amounts of these materials in the flue gas when the flue gas is at a temperature from about 250° F. to about 350° F. to retain the mercury within the aqueous phase. After the water evaporates, the oxidized mercury is retained on the dry flyash particles present in the flue gas. These flyash particles bound with the oxidized mercury are removed from the flue gas by a particulate removal device, such as an electrostatic precipitator, baghouse filter or cyclone.

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: In a method of removing metals such as mercury from flue gas produced by combustion devices, ammonia and optionally carbon monoxide are injected into the flue gas in a manner so that there are sufficient amounts of these materials in the flue gas when the flue gas is at a temperature of from 900° F. to 1350° F. to oxidize the metals within the flue gas. The oxidized metals are then attracted to particulates present in the flue gas. These particulates bound with oxidized metals are removed from the flue gas by a particulate removal device such as an electrostatic precipitator or baghouse.

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 tubular probe has spaced apart bands or patches of the same material as the probe body attached to the probe body by an electrically insulating, high temperature material. A series of cooling tubes are provided within the probe body to direct cold air to the regions near each band. One or more probes is placed in a furnace or boiler above the ammonia injection zone. When ammonium bisulfate forms on the probe it completes an electrical circuit between the probe body and the bands and will also cause corrosion of the probe. The presence of ammonium bisulfate is detected by a change in resistance between the bands and the probe body. Electrochemical noise is generated during the corrosion process. A corrosion rate can be determined from the level or amount of electrochemical noise that is detected.

Abstract: A tubular probe has spaced apart bands or patches of the same material as the probe body attached to the probe body by an electrically insulating, high temperature material. A series of cooling tubes are provided within the probe body to direct cold air to the regions near each band. One or more probes is placed in a furnace or boiler above the ammonia injection zone. When ammonium bisulfate forms on the probe it completes an electrical circuit between the probe body and the bands and will also cause corrosion of the probe. The presence of ammonium bisulfate is detected by a change in resistance between the bands and the probe body. Electrochemical noise is generated during the corrosion process. A corrosion rate can be determined from the level or amount of electrochemical noise that is detected.

Abstract: A method for monitoring and reducing corrosion in superheater and reheater furnace tubes measures electrochemical activity associated with corrosion mechanisms while corrosion is occurring at the surface of the tubes as they are exposed to combustion products. A sensor containing two electrodes spaced apart by an insulator is used. The surface of a boiler tube is one of the electrodes. The sensor is connected to a corrosion monitor. The monitor contains a computer and software, which determines a corrosion rate from the measured electrochemical activity. That rate is compared to a standard to determine if the rate is within acceptable limits. If not, the furnace operator of the furnace or an Adaptive Process Controller (APC) adjusts one or more burners to change the combustion products that are responsible for the corrosion.

Abstract: In a method of removing metals such as mercury from flue gas produced by combustion devices, ammonia and optionally carbon monoxide are injected into the flue gas in a manner so that there are sufficient amounts of these materials in the flue gas when the flue gas is at a temperature of from 900° F. to 1350° F. to oxidize the metals within the flue gas. The oxidized metals are then attracted to particulates present in the flue gas. These particulates bound with oxidized metals are removed from the flue gas by a particulate removal device such as an electrostatic precipitator or baghouse.

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 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 is provided for controlling the operation of a furnace. A furnace generally includes a boiler having a combustion zone, a plurality of burners burning a mixture of fuel and air in the combustion zone producing a gaseous by-product, and an electrostatic precipitator in fluid communication with the boiler removing particulates from the gaseous by-products. The method includes the steps of monitoring operating conditions of the electrostatic precipitator on a section-by-section basis, and controlling a select one or more of the burners based upon the section-by-section monitored operating conditions.

Abstract: In an improved method for reducing nitrogen oxide emissions from a furnace wherein at least one injector is attached to the furnace above the primary combustion zone a biomass or biowaste and water slurry is injected into the flue gas through the injectors. The biowaste or a biomass material can be supplemented with a fixed nitrogen source.

Abstract: In a furnace having a primary combustion zone for combustion of a fuel and oxidant, an in-furnace method for reducing nitrogen oxides in combustion products generated in the primary combustion zone in which at least one fluid fuel selected from the group consisting of natural gas, hydrogen, CxHy compounds, CxHyOz compounds and mixtures thereof in an amount in a range of about 2.0% to about 25% of a total heat input to the furnace and at least one nitrogenous compound selected from the group consisting of ammonia, amines, urea, cyanuric acid and mixtures thereof are injected into the furnace downstream of the primary combustion zone, forming an overall fuel-lean NOx-reduction zone.

Abstract: An in-furnace method and apparatus reduces nitrogen oxides in flue gas by injecting an oil water emulsion into flue gas so that the oil and water mixes with said flue gas. The emulsion has from 35% to 80% water and is injected in sufficient quantities to provide enough oil to promote a reaction between the nitrogen oxides in the flue gas and the oil, so as to reduce nitrogen oxide content of the flue gas and to maintain overall fuel lean conditions above the primary combustion zone. The emulsion preferably is atomized before injection and may also be injected in jet streams. Other materials such as limestone, ammonia and urea could be added to the oil water emulsion prior to injection.