Abstract: Devices, systems, facilities, and methods for post combustion capture of emissions from a natural gas generator used to power a data center disclosed herein. The facility includes a process for capturing and sequestering CO2 from a post combustion capture of the natural gas generator utilizing the heat from the flue gas and from the data center. The CO2 rich streams from the post combustion capture system are sent to sequestration of some form via a sequestration compressor, thereby reducing the overall emissions from the facility.

Abstract: A hot water supply device includes: a combustion part including a first burner part for which a flame sensor is disposed and a second burner part having a different number of burners from the first burner part such that one or both of the burner parts perform combustion, the flame sensor being configured to detect combustion state information of a flame generated by burners; a combustion control part configured to monitor a combustion mode of the combustion part set in accordance with a hot water supply request and change a second combustion mode in which the first burner part does not perform combustion, to a first combustion mode in which at least the first burner part performs combustion, when the second combustion mode is continuing; and a combustion adjustment control part configured to execute a combustion adjustment process of the combustion part.

Abstract: The present disclosure addresses systems, media, and methods of configuring a heating system comprising a plurality of combustion-type heating devices fluidly coupled to a vent system. Configuring the heating system includes receiving operating pressure data from one or more pressure sensors in a flue of one of combustion-type heating devices and the vent system. The operating pressure data from the one or more pressure sensors is indicative of a pressure at a corresponding location in the vent system. Configuring the heating system further includes comparing the operating pressure data to stored operational pressure data indicative of operational pressure ranges indicative of permissible operating parameters associated with preventing backflow of flue gases into the one of combustion-type heating devices and outputting instructions for a damper to at least partially open or at least partially close based at least in part on the operating pressure data and the stored operational pressure data.

Abstract: A portable indirect fuel fired heater includes a burner assembly having a fuel burner to deliver fuel from a fuel supply to a combustion chamber of the heater and a combustion air blower to deliver combustion air to the combustion chamber with the fuel for combustion in the combustion chamber to produce exhaust gases. A heat exchanger receives air to be heated in heat exchanging relationship with at least a portion of the combustion chamber. A sensor senses an oxygen level as a partial pressure of oxygen in the exhaust gases. A controller operates an actuator operatively connected to the burner assembly to controllably vary the delivery rate of combustion air and thus vary the ratio of the air and fuel responsive to the oxygen level sensed by the combustion sensor so as to maintain the sensed oxygen level at a prescribed set point level stored on the controller.

Abstract: A method is provided for printing a three-dimensional object. The method comprises, depositing a layer of metal powder onto a powder bed of a three-dimensional printer. A liquid is heated to generate a vapor. The liquid is removed from the vapor to dry the vapor by heating the vapor above a condensation temperature of the liquid. The dry vapor is deposited onto the powder bed of the three-dimensional printer.

Abstract: A burner control system for improving burner performance and efficiency may determine fuel and air channel or manifold parameters. Determination of parameters may be performed with a sensor connected across the air and fuel channels. A signal from the sensor may control the parameters which in turn affect the amounts of fuel and air to the burner via a controller. Parameter control of the fuel and air in their respective channels may result in more accurate fuel and air ratio control. One or more flow restrictors in fuel and/or air bypass channels may further improve accuracy of the fuel and air ratio. The channels may be interconnected with a pressure or flow divider. Byproducts of combustion in the exhaust, temperatures of gas and air, flame quality and/or other items may be monitored and adjusted with control of the fuel and air ratio for optimum combustion in the burner.

Abstract: Methods for regulating a heating device, which includes a combustion chamber, into which combustion air is introduced via a controllable blower. An operating variable and a speed of the blower are measured. An operating coefficient is determined on the basis of the measured operating variable and the measured speed. A volume flow coefficient is determined on the basis of reference values for the operating coefficient. A volume flow of the combustion air being determined on the basis of the volume flow coefficient. A calibration of the reference values is carried out for the operating coefficient.

Abstract: A furnace includes a controller configured to instruct a blower of the furnace to increase an exhaust flowrate of the furnace, instruct a gas regulation device of the furnace to increase a fuel input rate of the furnace, or both in response to a determination that the fuel input rate is below a threshold fuel input rate for a threshold time period. In some embodiments, the controller is configured to instruct the blower to maintain an increased exhaust flowrate for a flame-stabilizing time period the gas regulation device to maintain an increased fuel input rate for the flame-stabilizing time period, or both.

Abstract: Reversible draft controllers and exhaust systems incorporating reversible draft controllers are disclosed. One system for controlling draft in a chimney includes a sensor for determining condition data, an axial fan blade, an electronically commutated motor (ECM), and a controller. The ECM is configured to rotate the fan blade in a first direction to increase draft in the chimney and in a second, opposite direction to decrease draft. The controller has a processor and a program of instructions executable by the processor to perform steps for controlling draft in the chimney with the fan blade. The steps include: comparing condition data from the sensor to set point data to determine if an intervention is required; addressing insufficient draft by actuating the ECM to rotate the axial fan blade in the first direction; and addressing excessive draft by actuating the ECM to rotate the fan blade in the second direction.

Abstract: A burner control system for improving burner performance and efficiency. The system may determine fuel and air channel or manifold parameters. Determination of parameters may be performed with a sensor connected across the air and fuel channels. A signal from the sensor may control the parameters which in turn affect the amounts of fuel and air to the burner via a controller. Parameter control of the fuel and air in their respective channels may result in more accurate fuel and air ratio control. One or more flow restrictors in fuel and/or air bypass channels may further improve accuracy of the fuel and air ratio. The channels may be interconnected with a pressure or flow divider. Byproducts of combustion in the exhaust, temperatures of gas and air, flame quality and/or other items may be monitored and adjusted with control of the fuel and air ratio for optimum combustion in the burner.

Abstract: A steam power station is provided having a steam boiler which can be fired by a combustion device in a combustion chamber and has an air preheater which is suitable for removing thermal energy from the flue gas of the combustion chamber in order to transfer the thermal energy to a first air flow, the first air flow being fed back to the combustion chamber at least partly as combustion air. The steam power station also has a high-temperature battery which can likewise be supplied with air from the first air flow.

Abstract: The disclosure provides a controller for a multistage gas furnace, a multistage gas furnace and computer readable medium for performing a method to operate a furnace. In one embodiment, the controller includes: (1) an interface configured to receive a heating call and (2) a corrosion reducer configured to ignite the gas furnace at a high fire operation based on if an indoor circulating fan of the gas furnace is active.

Abstract: A burner control system for improving burner performance and efficiency. The system may determine fuel and air channel or manifold parameters. Determination of parameters may be performed with a sensor connected across the air and fuel channels. A signal from the sensor may control the parameters which in turn affect the amounts of fuel and air to the burner via a controller. Parameter control of the fuel and air in their respective channels may result in more accurate fuel and air ratio control. One or more flow restrictors in fuel and/or air bypass channels may further improve accuracy of the fuel and air ratio. The channels may be interconnected with a pressure or flow divider. Byproducts of combustion in the exhaust, temperatures of gas and air, flame quality and/or other items may be monitored and adjusted with control of the fuel and air ratio for optimum combustion in the burner.

Abstract: A first temperature distribution that represents a temperature of an element adjacent to and distinct from a first optical element that is positioned to receive an amplified light beam is accessed. The accessed first temperature distribution is analyzed to determine a temperature metric associated with the element, the determined temperature metric is compared to a baseline temperature metric, and an adjustment to position of the amplified light beam relative to the first optical element is determined based on the comparison.

Abstract: A controller includes a program for controlling a group of boilers having boilers with a plurality of staged combustion positions. The program is arranged to control the boilers and the combustion positions such that a total load following evaporation amount obtained by summing up load following evaporation amounts of the respective boilers comprising the group of boilers becomes equal to or more than a setup load following evaporation amount which is an evaporation amount that the group of boilers is to follow.

Abstract: Thermal targeting technology is used to continuously adjust boiler target temperature to the minimum necessary to satisfy the required heating load. Responsive to and initiated by a first call for heat, boiler target temperature is reduced by a predetermined amount upon or subsequent to the call for heat. Once the boiler temperature reaches this new target, a call timer is activated. If demand for heat is satisfied before a time set point is reached, the system ceases providing additional heat energy until the next heat demand. Responsive to and initiated by a next call for heat, the boiler target temperature is again reduced by the predetermined amount upon or subsequent to this next call for heat. Each time the heat demand is satisfied within the predetermined time interval, the boiler target temperature is reduced. If heat demand is not satisfied, a thermal boost is provided at set time intervals until the call for heat is removed.

Abstract: An improved method and system for flue gas recirculation (FGR) from the ID Fan located downstream of a scrubber (or other Air Quality Control Equipment including cyclones, baghouses, etc., hereafter “AQC equipment”) back to the scrubber (or other AQC Equipment) inlet to maintain the minimum required flue gas throughput during low-load conditions, thereby eliminating the need for a separate booster fan. A flue gas recirculation duct is connected from downstream of the ID Fan to the inlet of the scrubber (or other AQC Equipment). A variable flow restrictor is placed in the duct downstream of the ID Fan for controlling pressure of the recirculated flue gas. The flow restrictor is controlled in accordance to a function of boiler load or flue gas flow to produce the required backpressure that enables the flue gas to flow through the recirculation duct back to the inlet of the scrubber (or other AQC Equipment) at low loads.

Abstract: A controller includes a program for controlling a group of boilers having boilers with a plurality of staged combustion positions. The program is arranged to control the boilers and the combustion positions such that a total load following evaporation amount obtained by summing up load following evaporation amounts of the respective boilers comprising the group of boilers becomes equal to or more than a setup load following evaporation amount which is an evaporation amount that the group of boilers is to follow.

Abstract: A system of detection and analysis of gas or fuel oil flames using optical devices, consisting of a sensor that targets the flame's reaction zone through an optical access, a processing and control module, and an actuator, responsible for controlling the damper. The system optimizes combustion equipment operation by controlling the damper, obtaining better performance and reducing polluting emissions.

Abstract: Excess oxygen in the combustion process of a facility that bums carbon-based fuels may cause a visible plume in the atmosphere at the stack of the facility. Traditional optical based opacity monitors may be unable to detect this plume or the plume may form at a location downstream from the opacity monitor toward the stack. The present invention discloses methods to utilize common combustion control variables to detect and signal the presence of a visible plume of exhaust gasses. Also disclosed are systems that detect the visible plume and provide a signal so that the combustion process may be manually or automatically adjusted to reduce or eliminate the visible plume.

Abstract: A method and apparatus for achieving optimal combustion. A boiler has a blower-type burner operatively associated therewith wherein the burner has a variable speed blower. Combustive air is provided to the burner, and in accordance with the invention, a gaseous combustion-correcting complex is provided for supplying a plurality of gaseous additives to the combustive air of the burner. A plurality of sensors are disposed within the boiler and burner, and within a discharge outlet of the boiler, and a central unit is operatively connected to the sensors for receiving information signals therefrom. In response to the information signals received from the sensors, the central unit controls the speed of the variable speed blower and the operation of the gaseous combustion-correcting complex for providing predetermined amounts of the additives to the combustive air.

Abstract: The firing rate and the feedwater flow rate of a universal pressure boiler are controlled using a cascaded steam temperature control system. The secondary superheater outlet temperature comprises an outer loop for the control system, while the convection pass outlet temperature comprises an inner loop for the control system. Control variables for the system include the secondary superheater outlet temperature, the convection pass outlet temperature and the difference between the primary superheater outlet temperature and the secondary superheater inlet temperature.

Abstract: The present invention aims for the object thereof at preventing unburnt gas and noxious gas components from being generated in a refuse incinerator, and provides a combustion control method by which it is arranged so that a feeder (2) and a stoker (3) are not only controlled so as to keep evaporation (S1) of the boiler at a target value thereby to achieve stabilized combustion extending over a long period of time, but also feed water quantity (S2) and the like from a boiler water pipe section (2) forming a combustion chamber (6) are detected, and the rate of overfire air quantity to main combustion air quantity to a lower part of the stoker is controlled at a constant total gas capacity so that the fluctuation width of the feed water quantity (S2) falls within a set range.

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: The present invention provides a water heater capable of exhausting flue gases from an interior space of a building to an exterior space and is adapted for installation through an upstanding wall. The water heater has an insulated tank with a water inlet and a water outlet together with a flue pipe opening at one end thereof beneath the tank upon a combustion chamber containing a fuel burner. The other end of the flue pipe opens at the top of the tank upon a flue gas collector and has a flue gas restricter for restricting the outward flow of flue gases from the flue pipe. The collector includes a collector box connected to the top of the water heater above and in alignment with the flue pipe, a blower and a low temperature flue gas exhaust line. The collector box has at least one air inlet for mixing air from the interior space of the building with flue gases exiting the flue pipe to inhibit condensation and reduce the temperature of the flue gases flowing through the exhaust line.

Abstract: A steam boiler (2) including a fire tube (21) and convection heating surfaces (22) is preceded by a combustion chamber (30) including a surface burner (34) for high excess air. The combustion chamber (30) and the fire tube (21) are internally thermally insulated (33). The combustion air supply opening (37) of the burner (34) is connected by way of a blower (40) with an exhaust air source (1). A fuel control valve (36) is controlled as a function of the boiler load. A plurality of heat exchangers (47, 48, 49) are incorporated in the flue gas channel (45) following the convection heating surfaces (22). The most upstream heat exchanger (47) is connected on the water inlet side by way of a pump (51) to the water chamber (23) and on the water outlet side by way of a baffle (53) to the water-steam circuit of the boiler (2). With this system it is possible to purify all of the exhaust air from the exhaust air source (1) over a broad boiler (2) load range.

Abstract: A process is disclosed for controlling the combustion and temperature in an solid waste-to-steam incineration system comprising a grated combustion zone and a steam boiler. This control is achieved by a synergistic combination of oxygen enrichment of an air stream and liquid quench fed to the combustion zone. The disclosed process includes the steps of adjusting the amount of solid waste passing into the combustion zone in order to maintain a constant flow of steam leaving the steam boiler, adjusting the amount of liquid quench to the incinerator in order to maintain a constant temperature in the combustion zone and adjusting the amount of oxygen enrichment of the air stream in response to a change in flow of the liquid quench to the incinerator. An apparatus for accomplishing the foregoing is also disclosed.

Abstract: Apparatus is provided for controlling the burning of a volatile waste liquid together with a conventional fuel in a boiler in the form of a free-standing module which contains a flow-control valve for the waste liquid. This system includes a means for monitoring the position to the fuel-control valve for the conventional fuel and a separate means for monitoring the position of a controlled valve for feeding of the volatile liquid. The two monitoring means are coupled and comparisons are made of the relative valve positions indicated thereby. The process controller used for such comparison contols a valve which stops the flow of volatile liquid to the burner in the event that more than a predetermined discrepancy occurs between the indicated valve positions. Said controller may also be employed to correct the valve position. Other features include a reverse purge pumping system which is actuated upon shutdown of volatile fuel flow.

Abstract: Boiler operations are fine tuned to minimize thermodynamic losses and pressure losses across throttle valves at the output of a boiler. Whenever the boiler is operating outside of desired operating levels, the first action considered is to reduce spray flows into steam supplied into a reheater or superheater outputting steam at too low of a temperature. The second consideration is to reduce the use of auxiliary electrical power, such as fans supplying tempering air to the primary air used to carry fuel to the burners. The next consideration is selective soot blowing and damper adjustments to redistribute heat in combustion product exhaust gas in the boiler. Then, if possible, the quantity of flue (combustion product) as recycled is adjusted to modify the gas temperature and the heat transferred in the radiant (furnace and superheat) sections and the convective (reheat and economizer) sections of the boiler.

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: A multiple purpose instantaneous gas water heater comprises a combination of a larger combustion capacity type first burner with a smaller combustion capacity type second burner. Each of the burners can be controlled by a proportional combustion control method and/or an intermittent combustion control method. It is possible to combine these functions within a microcomputer system so as to use each or both burners selectively, or both together, so that it is possible to select water from a wide range of hot water temperatures or to select a target temperature.

Abstract: A fan forces air through an air inlet channel to a mixing chamber where it is mixed with fuel, and the mixture is then fed to a burner. The combustion products of the burner provide heat to a heat exchanger which is connected to a discharge channel. The contamination of the system is measured, and the speed of the fan is increased upon an increase in the contamination. The heating system is automatically prevented from operating when the contamination exceeds a predetermined value.

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: An apparatus for burning waste refuse having a heterogeneous composition comprising means defining a combustion chamber having an inlet for charging waste refuse therein and an outlet for discharging combustion gases therefrom, means disposed within the combustion chamber for agitating waste refuse charged therein, means for sensing the temperature differential of combustion gases emanating from the burning waste refuse disposed on the agitating means, between spaced points along the path of flow of the emanating combustion gases, and means responsive to variations of the sensed temperature differential relative to a preselected temperature differential for adjusting the operation of the agitating means.

Abstract: A multiple purpose instantaneous gas water heater comprises a combination of a larger combustion capacity type first burner with a smaller combustion capacity type second burner. Each of the burners can be controlled by a proportional combustion control method and/or an intermittent combustion control method. It is possible to combine these functions within a microcomputer system so as to use each or both burners selectively, or both together, so that it is possible to select water from a wide range of hot water temperatures or to select a target temperature.

Abstract: An economical despatching arrangement for despatching load and fuel assignments on a multi-boiler cogenerative type steam generating plant includes a logic arrangement of determining a present value of flow of each fuel to each boiler, a logic arrangement of determining a present value of the share of the steam load carried by each of the boilers, a logic arrangement for calculating an optimal next value for each of the load and fuel assignments, a logic arrangement for estimating a proportionate share value for one of the boilers and the fuel flow values for one of the fuels and a logic arrangement for implementing the optimal next values as a function of whether a manual or automatic mode of operation has been selected for the particular parameter.

Abstract: A safety device for subcritical natural and forced circulation boilers wherein the differential between downcomer fluid temperature and drum saturation temperature is measured and the trend of the differential is determined by computer means on a continuous basis. If the differential approaches a defined limit in its trend in a defined time interval or the furnace tube temperature increases instantaneously, the heat source for the boiler is diminished.

Abstract: A system for controlling steam temperature in a boiler using a time delay feedback controller known as a Smith Predictor to provide control tuning of true boiler parameters which change with load.

Abstract: According to the present invention there is provided a boiler comprising a firebox, a control device controlling the flow of air into the firebox, a water jacket surrounding at least part of the firebox, a sensor to sense the temperature of the water in or being discharged from the water jacket, the sensor being adapted to control directly or indirectly the control device. The sensor can be a temperature sensitive valve associated with the water jacket to control the position of the control device to thereby govern the flow of air to the firebox. The invention further provides a method of providing space heating and hot water from a boiler unit comprising the operation of a boiler unit.

Abstract: A boiler air flow controlling apparatus for feeding air in a desired air flow to a boiler by cooperation of a first fan for feeding air to the boiler with a second fan for sucking air from said boiler. The apparatus includes means for varying, when the number of poles of at least one of motors for the two fans is changed over, the opening of a damper located in an air course in order to restrict a variation of the inner pressure of the boiler upon such changing over to a value within an allowable range.

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: In a combustion system, the economic optimum efficiency is achieved by periodically computing a relative index of combustion efficiency using the combustion chamber as a real-time, on-line calorimeter. This is accomplished by first determining the combustion chamber inputs and outputs required to calculate a relative index of performance (including measuring the amount of heat released or work performed at the present air/fuel ratio including the stack losses, without oxygen and/or carbon monoxide sensors), sequentially comparing the latest relative index value with the previous value, then adjusting the air/fuel ratio to achieve an improved index value.

Abstract: The subject invention relates to an improved method and apparatus to control the rate of heat release (ROHR) from a reaction zone confined within a chamber, air and fuel having been introduced into said reaction zone to achieve combustion, plural sensors being utilized one sensor adapted to sense ROHR, another to generate a target value for a desired ROHR within a comparator, still another sensor to determine heat generation and transmit it to the comparator, a control means for controlling ROHR of heat generation and connecting said comparator with said control means to achieve coincidence between a target value and said sensed value.

Abstract: An automatic firing rate control mode arrangement is provided as a method of operation within a flame safeguard sequencer. The system uses proportional control squared, an integration which reflects the past load history to determine the present load, and further has a constant which relates the rate of change of pressure with respect to time in order to make more responsive the normal load control operation. The system is also capable of on-off control that will hold the system in low fire to allow for stabilization, and to avoid thermal shock to a boiler.

Abstract: An automatic stoker boiler has a heat transfer compartment above a combustion chamber which is divided by a horizontal partition inclined upwardly from the rear end of the boiler towards but terminating short of the front end thereof to provide a restricted port between the thus established upper and lower portions. An endless link belt establishes the lower portion of the combustion chamber and hot gas conduits extend from the upper portion through the heat transfer compartment to the exhaust and which is provided with a draft inducing fan and adjustable damper. Underfire air under the control of an adjustable damper is introduced into the lower portion of the combustion chamber upwardly through the belt and air jets are delivered into the combustion chamber through the front end both above and below the port. A standby fluid fuel burner is located in the rear end of the upper chamber portion.

Abstract: An apparatus for controlling a starting operation of a boiler which comprises a super heater, a super heater bypass valve, a turbine bypass valve and a fuel flow rate regulating valve. A temperature detector detects a temperature of the steam at a predetermined portion of the boiler. A pressure detector detect a pressure of the steam at the predetermined portion of the boiler. A desired change rate arithmetic unit calculates a desired steam temperature change rate value and a desired steam pressure change rate value on the basis of the steam pressure, the steam temperature, a desired pressure increase value, a desired temperature increase value, a saturated temperature change rate limit and a temperature increase change rate limit.

Abstract: A system for recovering the waste heat normally exhausted in the atmosphere by blast furnace stoves or other variable temperature process heaters. The system comprises a heat exchange apparatus located in the exhaust stack, heat transfer means for carrying the waste heat absorbed from the exhaust gases to a location remote therefrom, and a second heat exchange apparatus for releasing the transferred waste heat for beneficial use at the remote location. This invention also includes a reservoir for storing the heat transfer fluid used in the system and also the reservoir acts as a heat sink to moderate the temperature variation of the heat transfer fluid. The system also includes means for controlling temperature of the first heat exchanger and means for controlling the temperature of the variable temperature process heater. The preferred heat transfer fluid is maintained as a liquid during its use in the system.

Abstract: A control circuit for a stoker-fed heating system is effective, whenever the primary sensing control (thermostat or aquastat) of the system calls for heat, to determine whether there is sufficient fire in the furnace to assure maintained combustion, and if this is not the case, to shut the system down until combustion is again assured.

Abstract: Disclosed is an automatic anticipatory control system for controlling, by one common control quantity, a plurality of points of operation that can be changed over individually and arbitrarily between start and stop operations and between an automatic operation mode and a manual operation mode.

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.