Abstract: Apparatus provides an air/fuel mixture to a fully premixed burner and comprises means for providing fuel at a variable flow rate to the burner, means for supplying air at a variable flow rate to the fuel to form the mixture, means for sensing aeration of the fuel combustion products and control means for controlling the fuel flow rate in dependence upon a heat output demand and the air flow rate in dependence upon both the fuel flow rate and the sensed aeration in such a way that the air flow rate is sufficient to maintain the aeration at a predetermined value, the controller, in use, maintaining the fuel flow rate at one of a number of predetermined values and the air flow rate at a corresponding one of a number of differing predetermined values, each set of predetermined values being characterized by a constant value of the ratio between successive values.

Abstract: A combustion system is divided into a thermal decomposition section and a combustion section. The thermal decomposition section thermally decomposes or partially bums solid combustibles, thereby generating combustible gases. The quantity or quality of the generated combustible gases is measured, and combustion air corresponding to the measured value is supplied to the combustion section. The quality and temperature of the combustible gases in the thermal decomposition section are detected, and the quantity of solid combustibles and air (or the quantity of heat) supplied to the thermal decomposition section are controlled.

Abstract: For determining the average radiation of a surface region of a burning bed, an infrared camera is used in a firing installation, which camera is aligned with this region and is equipped by means of appropriate flame filters in such a way that it operates at the minimum of the interfering radiation emanating from the flame, whereby this interfering radiation is already largely eliminated. In order then also to eliminate the solids radiation from moving particles and thus to obtain a temperature measurement of the burning bed, recordings are made successively at short intervals of time by means of the infrared camera and these are evaluated in the evaluation and control device.

Abstract: Method and apparatus for reducing the NOX levels in stack emissions of compact boilers and fluid heaters through selective injection of exhaust flue gases into the combustion process. Flue gas injection into the primary and secondary air of the burner along with flue gas injection directly into the combustion process is utilized. Injection of generated steam obtained from various components of a compact boiler, selectively injected into the combustion process is also provided.

Abstract: Method and apparatus for reducing the NOX levels in stack emissions of compact boilers and fluid heaters through selective injection of exhaust flue gases into the combustion process. Flue gas injection into the primary and secondary air of the burner along with flue gas injection directly into the combustion process is utilized. Injection of generated steam from a compact boiler, selectively injected into the combustion process is also provided.

Abstract: A method and system for controlling and providing guidance in reducing the level of NO.sub.x emissions based on controllable combustion parameters and model calculations while maintaining satisfactory plant performance and not causing other harmful consequences to the furnace. To implement such a system, boiler control values of flow, pressure, temperature, valve and damper positions in addition to emission sensors for data associated with the production of NO.sub.x, O.sub.2, CO, unburned carbon and fuel. This information is received from standard sensors located throughout a boiler which are connected either to a distributed control system (DCS), or another data acquisition system which is time coordinated with the DCS. The DCS passes this information to a computing device which then processes the information by model based optimization simulation programs, also referred to as the NO.sub.x Emissions Advisor.

Abstract: A multi-loop control system and a method for using the control system to even out the generation of heat produced by a refuse incineration plant. The quantity of steam generated is controlled as a primary controlled variable and the oxygen content of the flue gas is controlled as a secondary controlled variable. This method makes it possible to improve other parameters in operating a refuse incineration plant.

Abstract: A method for operating an incinerator wherein fuel is provided into the incinerator separate from combustible waste and upon an increase in oxygen demand, initially refraining from proportionately increasing the oxygen provided into the incinerator and responding by decreasing the flow of fuel so as to control the generation of PICs without substantially raising the incinerator temperature. The oxygen flow is increased when the fuel flowrate has been reduced to a predetermined minimum should this occur.

Abstract: A draft control for material processing apparatus, such as asphalt plants, having a chamber through which material to be processed is passed for contact with combustion gases and heat originating in a fuel supplied burner which may require a draft to draw air into the chamber for complete combustion of burner supplied fuel and to exhaust the products of combustion and other gaseous materials from the chamber. The air pollutants and the percent oxygen in the exhausted gases are monitored, and the draft is adjusted between minimum and maximum values for a given burner set point when the air pollutant content of the stack gases exceeds a predetermined maximum limit. The direction of draft adjustment is determined by the percent oxygen in the exhaust gases.

Abstract: Disclosed is a system for regulating the efficiency of a combustion process by detecting radiant energy emitted from ash particles entrained in the gas stream exiting the combustion chamber of a boiler or incinerator. The intensity of selected wavelengths of light emitted from the particles is indicative of the temperature of the particles. The change in the intensities of the selected wavelengths of light, and thus of the temperature of the gas stream at the furnace exit, is monitored, and a feedback control mechanism is used to regulate one or more combustion, pollution control, or heat transfer parameters thereby maximizing the thermal efficiency of the combustion process in the boiler or incinerator.

Abstract: An apparatus for detecting the presence of carryover particles in an upper region of a furnace, such as a smelt bed boiler, includes plural spaced apart detectors. These detectors monitor discrete portions of the interior of the furnace for the purpose of detecting carryover particles in such monitored portions. Signals indicative of the carryover particles are processed to obtain a count of the carryover particles. The carryover particle count may then be displayed. For example, the signals from all of the detectors may be averaged with trends and overall changes in count rates then displayed. In addition, the counts from the individual detectors may also be displayed to assist an operator in locating the source of excessive carryover particles in the furnace. An image sensor, such as a charged coupled device (CCD) detector, may be used to provide a visual display of detected carryover particles.

Abstract: The combustion of fuel having a highly fluctuating thermal value is controlled to permit optimization of air supply and reduction of waste gas impurities. The fuel passes through a combustion chamber having a degassing and evaporation zone, a primary combustion zone, and a secondary combustion zone. Measurements are taken in the evaporation and degassification zone to determine the thermal value of the fuel. This is done by detecting the intensity of H.sub.2 O and/or CO.sub.2 spectra emanating from the fuel. The measurement results are utilized to optimize the combustion parameters. Such measurements are also made in the following zones in order to provide further control of the combustion process.

Abstract: The method for regulating the furnace output in incineration plants, particularly waste incineration plants, in which the O.sub.2 moist content measured in the flue gas is used as an overriding reference value regulating variable for regulating the combustible material feed and the measured steam mass flow is used as a subordinate reference value regulating variable (10) for regulating the primary air supply, provides, according to a first variant, that the preselected O.sub.2 moist reference value (7) is changed as a function of the furnace temperature (6) measured in the flue gas. This changed regulating variable (9) is fed to a regulator (13l ) which influences the combustible material feed and/or the grate drive.

Abstract: A furnace for controlling flame temperature and emission of NOx comprising a burner to which fuel and air are supplied and product of combustion are discharged, wherein said air is vitiated with said products of combustion; a means for sensing furnace operating parameters including a flow rate sensor for sensing a flow rate of fuel to said burner and a first temperature sensor for sensing furnace temperature; and a means for controlling the amount of air vitiated with products of combustion, said controlling means in communication with said sensing means such that the amount of products of combustion vitiated with the air is controlled as a function of at least one of the rate of flow of fuel to said burner, the air temperature, and the furnace temperature, said control means is responsive throughout a firing range of said burner.

Abstract: The combustion of fuel having a highly fluctuating thermal value is controlled to permit optimization of air supply and reduction of waste gas impurities. The fuel passes through a combustion chamber having a degassing and evaporation zone, a primary combustion zone, and a secondary combustion zone. Measurements are taken in the evaporation and degassification zone to determine the thermal value of the fuel. This is done by detecting the intensity of H.sub.2 O and/or CO.sub.2 spectra emanating from the fuel. The measurement results are utilized to optimize the combustion parameters. Such measurements are also made in the following zones in order to provide further control of the combustion process.

Abstract: The method of operation of a boiler system to which an additive is to be fed at a controlled rate and in which the optimal additive rate depends upon a plurality of changing parameters of the boiler system, in which the relationship between each of those parameters and the optimal additive feed rate is determined, the relevant parameters are sensed during the operation of the system, their effects on optimum additive feed are computed in accordance with said relationships and combined on a continuous basis to produce a control signal representative of the desired rate of additive feed, and controlling the additive feed in accordance therewith, all preferably continuously.

Abstract: A combustion controller controls the supply of combustion gas to the combustion barrel of a rotary combustor used for incinerating solid waste material. The rotary combustor includes a combustion barrel having a gas-porous side wall and windboxes underneath the combustion barrel to supply the combustion gas to support incineration of the waste material into combustion products which include exhaust gases. The windboxes receive combustion gas via individual control ducts which are controlled by the combustion controller to regulate the corresponding supplies of combustion gas and thereby to provide substantially complete incineration of the solid material. An oxygen sensor detects the percentage of oxygen present in the exhaust gases and the combustion gas supplied to the combustion barrel is controlled to maintain the percentage of oxygen near a predetermined level.

Abstract: An apparatus for controlling operation of a recovery boiler for compensating a predetermined reference temperature of black liquor by a compensation value in accordance with a type of an injecting gun provided in the boiler, a compensation value set by the properties of the black liquor, a compensation value set by the temperature of charbed and a compensation value set by an air flow rate to the boiler representing the magnitude of boiler steam output or load to control the black liquor temperature supplied to the boiler.

Abstract: A method and device 15 is provided for a quick, accurate and on-line determination of heats of combustion of gaseous hydrocarbons. First, the amount of oxygen in the carrier stream air is sensed by oxygen sensing system 20. Second, three individual volumetric flow rates of oxygen, carrier stream air, and hydrocarbon test gas are introduced into burner 19. The hydrocarbon test gas is fed into burner 19 at a volumetric flow rate n measured by flowmeter 18. Third, the amount of oxygen in the resulting combustion products is sensed by oxygen sensing system 20. Fourth, the volumetric flow rate of oxygen is adjusted until the amount of oxygen in the combustion product equals the amount of oxygen previously sensed in the carrier stream air. This equalizing volumetric flow rate is m and is measured by flowmeter 16. The heat of combustion of the hydrocarbon test gas is then determined from the ratio m/n.

Abstract: For continuous combustion air control in a hazardous waste incinerator, two signals are generated which totalize the air required on a fuel supplied basis. One signal is responsive to measured totalized fuel flow and this total can include fuel flow signals which are limited to the fraction of available air which corresponds to the fuel flow. The other signal is responsive to the totalized fuel flow that is commanded for maintaining an incinerator condition. In use the signal which requires the greater air flow is selected as the actual control signal for combustion air, and this control signal is biased to increase the air flow to obtain complete combustion of the hazardous waste by a controller acting on the measured amount of oxygen in the flue gas. In this manner the combustion air is manipulated in parallel with the waste fuel and if the fuel flow is limited by the available air, the air flow is limited to match the limited fuel flow.

Abstract: A modification of a basic jack-shaft control apparatus for a combustion system to provide a trim control. A first radial arm is mounted on a first rotating shaft which controls a fuel valve and a second radial arm is mounted on a second rotating shaft which controls an air damper. Ordinarily, a linking rod connects the radially outward ends of said first and second radial arms. The trim modification comprises attaching one end of a third radial arm to the radially outward end of either said first radial arm or said second radial arm. A third rotating shaft is attached to the third radial arm where it is attached to said first or second radial arm. The third radial arm rotates under the influence of trim control motor means on a plane transverse to the plane of rotation of the arm on which it is mounted. The linking rod connects the radially outward end of the third radial arm with the radially outward end of either said first or second radial arm to which the third radial arm is not otherwise attached.

Abstract: A system for utilizing a fuel having a high ash content, water content in excess of 50% and large particles of combustibles is shown which includes a holding tank for the fuel. Fuel is circulated in the holding tank to maintain the consistency of the fuel and a metered portion is removed, strained and fed to a combustion device. The combustion device is a fire tube boiler for generating steam and includes a furnace tube insulated with refractory material extending for its entire length. The system mixes a preselected amount of atomized fuel with combustion air and natural gas. Special ash and particulate accumulation means are provided in the boiler. The boiler also has a water spraying system in its combustion chamber to reduce combustion temperature and increases water content of the combustion mixture based on the temperature of the combustion gases at the end of the furnace tube. Finally, when the boiler is shut off, the entire system, including a bypass system, may be purged by air or water.

Abstract: An installation for monitoring combustion to control pollution and retard other deleterious effects of improper combustion employs a smoke sampling duct to draw off a portion of the smoke emanation from the combustion chamber. The smoke in the sampling duct flows past a probe and is then vented from the duct. The probe senses oxygen or other substances in the smoke and emits signals to a device which analyzes the quality of combustion. A gas inlet in the sampling duct is situated upstream of the probe and gas is intermittently discharged into that duct to ascertain whether the probe is operating properly.

Abstract: The invention relates to a method of measuring dry substance in the flue gas in liquor recovery units in mills for the manufacture of papermaking pulp in order thereby to render it possible to control the operation of the unit. According to the invention, this is carried out in that the radiation emission caused at the combustion of fuel particles in the hearth of the unit above the fuel supply level is detected optically, and that the signals are used for indication and/or control of the operation of the unit.

Abstract: A system for the automatic and continuous determination of the efficiency of a fossil fuel-fired vapor generator for utilization by an automatic load control (88) to control the distribution of the system load among a plurality of generators, wherein various heat losses from various combustion sources are separately determined, the individual losses summed (80) and subtracted (86) from 100 percent to obtain a measure of the vapor generator efficiency.

Abstract: For determining the ratio in which two constituents are blended in a mixture comprising an oxygen-carrying gas and a gaseous fuel to be combusted by a primary combustion system, the thermodynamic conditions (composition, pressure, temperature) of the two gases prior to and after blending being variable, a secondary combustion system reacting part of the fuel and part of the oxygen-carrying gas is used as a reference combustion chamber. A mixture reproducibly analogous with the mixture burnt by the primary combustion system is used for reaction in the reference combustion chamber. Combustion in the reference combustion chamber is measured to obtain at least one signal for measuring and controlling the ratio between the two constituents of the mixture burnt by the primary combustion system, the reference combustion chamber allowing the rapid, accurate and reliable determination of the ratio between the gaseous fuel and the oxygen-carrying gas contents of the mixture burnt by the primary combustion system.

Abstract: A steam-generator control method is proposed for controlling the mass flows f an oxidant and a fuel which are supplied for combustion. In order to control the flows at stoichiometric ratios with a required accuracy, the controlled variables are established by the measurements of the mass flows and their comparison with theoretically predetermined stoichiometric ratios. Measurement errors are defined continuously through a combustion-gas analysis, conducted by means of a probe after the combustion. The errors are used for the correction of the controlled variables. The time constant of the correction is smaller than the time constant of dynamic changes of the errors.

Abstract: A CO sensor is mounted on the heat exchanger of a gas water heater (or other combustion unit) and is connected in circuit with a detecting unit mounted separately from the heater. The detecting unit generates a control voltage in opposition to a reference voltage on a solenoid. The solenoid controls a valve in a fuel supply passage to a burner (or burners) in the heater, thereby shutting off the burners when the CO concentration reaches a predetermined value. A timing circuit may be added to cut off the burners whenever a lesser CO concentration continues for a predetermined time period.

Abstract: A process is provided for carrying out the cryogenic cooling of a material which comprises introducing material to be cooled into an elongated cryogenic tunnel housing on means for conveying said material from an inlet end to an outlet end, spraying liquid cryogen onto said material as it travels through said tunnel at a position proximate said outlet end, passing vapor or gas derived from said liquid cryogen in counter-current flow over said material passing through the tunnel, removing from said tunnel at a position proximate said inlet end an exhaust comprising said vapor or gas and atmospheric air entrained thereby through said inlet end, determining the rate of flow of the exhaust and the content of molecular oxygen in said exhaust, and calculating from the rate of flow of the exhaust and its oxygen content the rate of consumption of said liquid cryogen.

Abstract: The burner system includes an apertured burner plate with low thermal conductivity which is adapted to be positioned in a closed combustion chamber. A mixing chamber below the combustion chamber has a gas inlet and an air inlet. A fan is operatively arranged in the mixing chamber. A detector provides an electric detection signal which varies with the composition of the burnt gas in the combustion chamber. The detection signal is applied to the input of an electronic control unit, which in response to the detection signal produces at least one output signal. Control means are responsive to the output signal for controlling the air-gas mix supplied to the mixing chamber.

Abstract: A method and apparatus for controlling the combustion of multiple fuels, especially fuels having diverse combustion air requirements. A heating rate demand signal indicative of the heating rate desired is generated and is compared with a fuel based fuel heating rate signal. The larger of the two signals is selected to be an air demand signal that serves as set point for a combustion air controller. The flow rates of each of the fuels being burned is monitored and the resulting signals are scaled and summed to produce the heating rate signal. The fuel signals are also scaled by factors reflecting the combustion air requirements of the fuels. The signals are summed and combined with the fuel heating rate signal to produce a feedforward signal which in turn is combined with a signal reflecting the measured combustion air flow to produce an equivalent air heating rate signal.

Abstract: A system for minimizing combustion operation losses includes measuring a load index for the combustion operation which is proportional to the fuel demand or the output thereof, measuring an amount proportional to the air heating losses of the combustion operation and measuring an amount which is proportional to the fuel loss of the operation. The air heating loss is measured by multiplying a flue temperature by an amount of unburned oxygen in the flue gas. This quantity is multiplied by a cost factor for such air heating and the load index. The fuel loss is obtained by measuring an amount of by-product in the flue gas as well as the opacity of the flue gas. These are multiplied by appropriate cost factors which in the case of opacity is proportional to a fine that would be due for violating certain limits for the opacity. Minimum values are found for the fuel loss and air heating loss quantities, as air demand to the combustion operation is changed.

Abstract: A method for controlling a process heater in which a required heat demand is computed based on the enthalpy of the feed stock and the desired enthalpy of the final product, and then used as a feedforward portion of the fuel control. A second embodiment of the invention is based on the assumption that the feed stock enthalpy changes slowly or infrequently. In this embodiment fuel heating value changes are used as a feedforward portion of the fuel control.

Abstract: A combustion system to utilize particulate fuel where the fuel is compressed and extruded into a selected shape to be burned in a combustion chamber under conditions where particles of burning material are maintained in the combustion chamber until the weight of the particulate material decreases to the point where the particle is carried from the chamber through a heat exchanger by combustion gasses to a scrubber section for removal of impurities such as SO.sub.2 and NO.sub.x.

Abstract: An improved combustion control system for a jackshaft controlled boiler or the like utilizes a second power actuator, a linkage biasing mechanism and a function generator which provides a position control signal as a function of the boiler load in order to position the linkage biasing mechanism to obtain an automatically calibrated, near optimum relationship between fuel and air. An alternative embodiment of this invention includes a flue gas analysis system where the position control signal is modified to further enhance combustion efficiency. This invention also includes a method for programming a programmable combustion control system according to this invention.

Abstract: The well-known "jackshaft" positioning or two-point parallel combustion control system has been modified to include a linkage strut length adjustor apparatus with a remote actuator apparatus. The adjustor apparatus includes an overload protection system to prevent damage to the linkage and control members of the combustion control system.

Abstract: The safety valve of a fan heater is operated by a detector pipe, the outlet of which is shielded from its inlet and communicates with the warm wind circulating fan of the heater to forcibly draw burned gas into the detector pipe for stable flow therethrough. A timed delay stops operation of the fan only after the flow of gas has been shut off by the safety valve for a time sufficient to discharge combusted gas from the detector pipe.

Abstract: A method for optimizing combustion air flow to a furnace. As the air/fuel ratio changes or is periodically perturbated, the corresponding change in heat loss to the stack due to the change in the amount of combustibles in the flue gases is maintained equal to the change in heat loss to the stack due to changes in the amount of excess air in the flue gases. The control is carried out by continuously modifying the air/fuel ratio in the appropriate direction to maintain that equality.

Abstract: A two-stage starved air furnace system is controlled to simultaneously achieve desired temperatures and percent stoichiometric air operation in the primary stage by modulating transformation relay functions acting upon measured temperature deviations to change both primary combustion air and primary auxiliary burner operation. At the set-point value of percent stoichiometric air, the relay functions are modulated in reverse direction to satisfy changing heat demands.

Abstract: Oxygen content in the exhaust gas of a combustion system is controlled such that the actually detected value of the oxygen content is compared with a set value which is varied in accordance with the combustion load of the system. A value theoretically adapted to control an air-fuel mixing ratio is calculated from the combustion load and the result of the comparison, and the flow rates of air and fuel supplied to the combustion system are controlled according to this value.

Abstract: An efficiency improving apparatus (A) improves the combustion efficiency of a combustion apparatus (B) which includes a combustion chamber (10), a fuel supply rate regulator (32), an air supply rate regulator (42) and a combustion control (20) to control the fuel supply rate in response to firing rate demands and to control the air supply rate in relation to the fuel supply rate so that a preselected program of combustion conditions will be maintained during random variations in air and fuel quality, as well as during rapid changes in firing rate. The efficiency improving apparatus is connected between the combustion control and the air regulator to alter the air-fuel volume relationship by a percentage.

Abstract: A process for the surveillance of jacketed radiant heating tubes and recuperative burners using a detector responding to the oxygen partial pressure in the exhaust gas. At low exhaust gas temperatures down to 200.degree. to 300.degree. C., an abrupt change in the detector output signal occurring due to the transition from over-stoichiometric to under-stoichiometric combustion and vice-versa is detected and is reproduced as an actuating and/or alarm signal. The process can also be used for flame surveillance, for the determination of leaks and cracks in jackets, and for surveillance of the tightness of closed magnetic gas valves.

Abstract: In a low NO.sub.x emission incinerator a refuse supply stoker (1), a dry-ignition stoker (2), a gas generation stoker (3), and a complete combustion stoker (4) are positioned in descending stair-step fashion beneath a combustion chamber (A). In the dry ignition stoker (2) and the gas generation stoker (3) refuse is thermally decomposed under an amount of air which is less than the amount of air theoretically required for complete combustion, so that reducing gases such as CO, NH.sub.3, and the like are generated. At the complete combustion stoker (4) the residuum of the refuse is completely combusted under an amount of air greater than the required theoretical amount. Air is supplied through nozzles (7,8,9) at successive points above the flow route of combustion gas inside the combustion chamber (A) so that the temperature in the combustion chamber (A) is maintained in a range to reduce the amount of NO.sub.x generated by the combustion of gases.

Abstract: Apparatus for controlling the combustion of natural gas in a natural gas fired appliance is described. Exhaust gases are sampled and maintained at a predetermined constant temperature between the dew point and the steam point. The relative humity of the constant temperature gas is monitored by a hygrometer. Relative humidity deviations from a predetermined value result in output signals from the hygrometer to a control circuit. The control circuit is connected to regulators in the air intake or chimney of the appliance which regulate air intake to keep the relative humidity substantially constant and hence control combustion of the gas. In another embodiment the relative humidity of the exhaust gases and the combustion air intake are monitored by separate hygrometers which are linked to each other so that a change in the relative humidity of a gas affecting one hygrometer will compensate the other hygrometer and control combustion as before.

Abstract: A method and apparatus for controlling the heat load in a plant fed with natural gas of variable calorific value and density consisting of withdrawing a portion of gas from the feed line, burning it in a special combustion chamber, withdrawing the combustion products from the chamber, determining the quantity of free oxygen contained in the dry burnt gas and varying the volumetric throughput of the natural gas on the main line.

Abstract: A combustion control apparatus of a combustion furnace by an improved fuel and air complementary control system according to master control system is disclosed, which is provided with a regulating means connected to a master controller and adapted for detecting the amount of load change and for setting the length of an air damper control rod's length changing device to a preset standard value corresponding to the load, without controlling the oxygen concentration in the exhaust gas to a standard value, when the load change is increased to a value of not lower than the preset value. The combustion control apparatus can control stably the oxygen concentration in an exhaust gas to a low level even when a load is suddenly changed.

Abstract: An improved combustion control system for a jackshaft controlled boiler or the like utilizes a second power actuator, a linkage biasing mechanism and a function generator which provides a position control signal as a function of the boiler load in order to position the linkage biasing mechanism to obtain an automatically calibrated, near optimum relationship between fuel and air. An alternative embodiment of this invention includes a flue gas analysis system where the position control signal is modified to further enhance combustion efficiency. This invention also includes a method for programming a programmable combustion control system according to this invention.

Abstract: In a cooking oven which is cleaned by pyrolyzation of soil within the oven cavity and has a smoke eliminator duct extending through the oven wall, with a smoke eliminator heater disposed adjacent to the duct inlet, a reducing gas sensor is mounted either adjacent to the oven end of the smoke eliminator duct or within the smoke eliminator duct near its discharge end. An electrical relay or microcomputer control is coupled between the gas sensor and the heater to initially heat the oven interior and to later deenergize the heater when the reducing gas sensor output indicates a desired oven condition. The oven heaters are temporarily deenergized when the gas sensor output indicate a smoke eliminator overload. If the gas sensor is mounted in the smoke eliminator duct, the smoke eliminator heater may be deenergized toward the end of the cleaning cycle, so that the effluent is not affected by the smoke eliminator heater before reaching the gas sensor.

Abstract: The well-known "jackshaft" positioning or two-point parallel combustion control system has been modified to include a linkage strut length adjustor apparatus with a remote actuator apparatus. The adjustor apparatus includes an overload protection system to prevent damage to the linkage and control members of the combustion control system.

Abstract: A method for controlling two-stage combustion furnaces having a first stage operated with sub-stoichiometric airflow and a second stage operated with excess air, whereby the first stage airflow is controlled such that the ratio of first stage airflow to total airflow is maintained less than ##EQU1## where N lies between zero and unity.