Abstract: A given target temperature profile T is produced in a workpiece as it passes through an elongated passageway of a belt furance by the steps of: (1) determining a set of temperature setting TS.sub.X for the belt furnace thermostats which satisfy an equation f(.alpha.,TS.sub.X,CF.sub.Y).apprxeq.T where .alpha. is a set of thermal parameters for the workpiece, CF.sub.Y is a set of correction factors, and f( ) is a function which approximates the temperature of said workpiece based on TS.sub.X,.alpha., and CF.sub.Y ; (2) measuring an actual temperature profile A(TS.sub.X) of the workpiece in the furnace with the heater thermostats at the settings TS.sub.x ; (3) terminating if the measured actual temperature profile A(TS.sub.X) matches the target temperature profile T within a predetermined tolerance; otherwise, (4) determining a new set of correction factors which satisfies an equation f(.alpha.,TS.sub.X,CF.sub.Y)=A(TS.sub.X); and thereafter repeating the above steps.

Abstract: A computerized method of digitally controlling the temperature profile of a heated article in which the temperature profile is defined by a plurality of temperature zones spaced about the article. The temperature profile of the article is monitored and a heating cycle requirement of the temperature zones of the profile is computed. A train of minute increments of power is supplied to heat each respective zone in accordance with the computed heating cycle requirements to achieve a precision approximately between .+-.0.1.degree. and .+-.0.5.degree. C. in a temperature range of approximately 400.degree. C. to 1,350.degree. C.

Abstract: A computer system for a zone fired furnace generates a plurality of temperature set point signals for a plurality of furnace zones. The set point signals are derived from a master controller acting on the measured temperature of fluid that is heated in the plurality of furnace zones and then combined to form a heated stream. The master signal, which is a velocity type signal, is provided to a plurality of zone control stations corresponding to the plurality of furnace zones. Each zone control station integrates the master signal, and then biases the master signal for use as a zone temperature set point. The zone control station can be used to bias the individual coils so as to balance the temperature of the coils with respect to each other, or to intentionally unbalance one or more coils, as desired, so as to improve furnace operations.

Abstract: A supervisory computer automatically equalizes the temperature of effluent streams of a multipass heating system to maximize heat transfer, without substantially disturbing a desired total flow through the heating system. Temperature control is achieved by manipulating the division of a feed stream among the multiple passes. In addition, if the flow in one or more passes cannot be manipulated, the control scheme automatically equalizes the temperatures of the remaining passes. This is accomplished by calculating a flow rate for adjusting the flow through the number of passes under supervisory control to a value, which in addition with any uncontrolled flow, will provide the desired total flow through the heating system. This adjusted flow rate is used as an approximate set point for the flow rate in each controlled pass. The adjusted flow rate signal is modified for control of each individual pass by applyng a bias through a conventional controller acting on a weighted average temperature signal.

Abstract: In a process in which a furnace having multiple coils is utilized to heat a fluid stream, a comparison of a measured pressure of the fluid stream to a desired pressure is utilized to bias a temperature control system for the furnace which maintains the furnace outlet temperatures from the plurality of coils substantially equal so as to substantially maximize the transfer of heat to the fluid stream while maintaining a desired pressure for the fluid stream. If multiple furnaces are utilized, a bias term based on a comparison of the total flow through each furnace may be utilized to bias the temperature control system so as to maintain a desired split in the total flow between the plurality of furnaces.

Abstract: Disclosed is a vacuum furnace temperature controller for the stable regulation of temperature over a wide range of temperatures. The control loop includes a multiplier responsive to the desired temperature which modifies the overall loop gain and the maximum power which may be applied to the furnace heater as a function of the desired temperature.

Abstract: The control of the flow rates of multiple fuel streams to furnace burners is accomplished by manipulating the flow rate of each fuel stream in response to a calculation of the heat duty which must be supplied by the respective fuel stream. Where the supply of a preferred fuel is variable, the flow rate of the other less preferred fuel stream is varied in response to changes in available supply of the preferred fuel to insure that sufficient fuel is available to the burners to maintain a required process temperature.

Abstract: Gas is circulated within the chamber of a heat treating furnace by a fan which is driven by an electric motor. The current drawn by the motor is detected and, when the current exceeds a predetermined magnitude, the density of the gas in the chamber is reduced to prevent an excessive load from being imposed on the motor. The density of the gas is reduced by shutting off the flow of gas to the chamber and by exhausting gas from the chamber.

Abstract: Apparatus for monitoring product temperature in a furnace, the furnace being of the open ended and secondary emission type, and having a plurality of serially arranged heating zones therein, each of the zones being adjustably heated. The furnace includes a conveyor which passes therethrough for carrying product thereon through the furnace. As is conventional, the furnace includes an outer casing or wall and an inner muffle with a cavity therebetween. Heaters are provided for applying heat to the cavity to heat the wall of the muffle. Tubes are provided for passing through the casing and into the muffle so that temperature sensing means may pass through the tubes into the muffle superimposed of the conveyor. The temperature sensors are connected to a monitoring system for amplification and for monitoring the temperatures directly of at least the critical zones of the furnace so that adjustment of the temperature may be made within preselected zones without causing loss of product.

Abstract: A process liquid circulation and temperature control system including a pump for circulating water or other process liquid through a path including a heating unit, a cooling unit, and a process apparatus that is returned to the pump; the pump and the heating and cooling units are actuated in response to temperature/pressure variations sensed at the return from the process apparatus and at the delivery thereto. One pressure control measures the differential pressure across the pump and inhibits system operation except when the differential exceeds a predetermined magnitude in a given direction; another pressure control inhibits operation if the return pressure falls below a given threshold; a circuit that determines .DELTA.P/T prevents boiling of the process fluid. For both temperature and pressure controls, the delivery and return sensors are calibrated to match each other on system start-up.