Abstract: A surge control system (16) is provided for a compressor (14) which anticipates the actual surge condition and initiates anti-surge protection in proportion to the magnitude of the anticipated surge condition. This is done by providing a feed forward signal (20) to a summing station (48) along with a normally generated surge control line point (44) to offset this point (44) by an amount determined by the feed forward signal (20). This offset point (50) is used as an input to a controller for controlling the bypass valve (28) in a bypass loop (30) around the compressor (14).

Abstract: A surge control system (16) is provided for a compressor (14) which anticipates the actual surge condition and initiates anti-surge protection in proportion to the magnitude of the anticipated surge condition. This is done by providing a feed foward signal (20) to a summing station (48) along with a normally generated surge control line point (44) to offset this point (44) by an amount determined by the feed forward signal (20). This offset point (50) is used as an input to a controller for controlling the bypass valve (28) in a bypass loop (30) around the compressor (14).

Abstract: A technique for producing a three-dimensional holographic display which is updatable in real time is disclosed. A spinning lens device intercepts a two-dimensional display on a projection television receiver and transforms same into a three-dimensional holographic display in free space. The holographic display is modifiable by the control room operator and process control variables can be readily superimposed thereon.

Abstract: A carbon monoxide detector comprises a single monochromatic infrared source which is arranged to alternately direct light through two separate gas-containing test chambers. The first chamber is supplied with gas to be tested which has an unknown carbon monoxide content. A catalytic burning chamber is connected between the first and second chambers to receive gas from the first chamber, burn the carbon monoxide in the gas to carbon dioxide and supply the carbon monoxide free gas to the second chamber. A single infrared light detector is provided for receiving light as it comes alternately from the two chambers. The light from the two chambers is compared to determine the amount of carbon monoxide present in the gas of the first test chamber. Since the same background gas is provided in both chambers and only a single infrared source and detector are utilized, inaccuracies due to differences in background detection, infrared source intensity and infrared detector sensitivity are overcome.

Abstract: A display system for displaying select dynamic process data of plant operations to an operator providing a display of only dynamic data having a predetermined difference between current and stored values.

Abstract: A performance monitor generates a fouling factor which indicates the level of fouling of a heat exchanger having a heat exchange surface area and through which a heat exchange medium passes having a known specific heat. Temperature transmitters are utilized to obtain values for the input and output temperatures of the heat exchange medium as well as the temperature in the heat exchanger of a heat exchange fluid used to transfer heat to or from the heat exchange medium. Modules are used to generate a value for an actual heat transfer coefficient in the heat exchanger as a function of the temperatures, flow rate and constant parameters such as area and specific heat, for the heat exchanger. The actual heat transfer coefficient is compared with a nominal or original heat transfer coefficient to determine if any deterioration in the coefficients has occurred which reflects the fouling of the heat exchanger.

Abstract: A system for processing and selectively transmitting process signals to a computer and/or a display device is disclosed. The system utilizes a binary full adder (38) to add the incoming signal, in inverted form, to the previously transmitted signal to obtain the difference therebetween. A binary comparator (52) compares the difference with a predetermined value, established by thumbwheel switches (46), and if the difference exceeds the predetermined level, causes the actuation of a flip-flop (54) and a bistable latch (32) permitting the incoming signal to be transmitted to a computer and/or a display device.

Abstract: An adaptive gain surge control system (18) is disclosed for a centrifugal compressor (14) which reacts to both normal and emergency surge conditions by controlling a bypass valve (48) across the compressor (14) inlet and outlet in response to a variable gain (G) determined by the offset (d) of the surge control line from the surge line of the compressor.

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: An adaptive gain surge control system (18) is disclosed for a centrifugal compressor (14) which reacts to both normal and emergency surge conditions by controlling a bypass valve (48) across the compressor (14) inlet and outlet in response to a variable gain (G) determined by the offset (d) of the surge control line from the surge line of the compressor.

Abstract: A system for optimizing the performance of a plurality of energy conversion devices is disclosed. Measurements of fluid flow into and out of the energy conversion devices, the efficiencies of the conversion devices and the power produced by the conversion devices are used as inputs to function blocks in a logic arrangements. The function blocks cause a decrease in load demand to be applied to the energy conversion device having the lowest efficiency and an increase in load demand to be applied to the energy conversion device having the highest efficiency.

Abstract: A three-mode analog controller for regulating a signal corresponding to a controller variable to produce a controller output, comprises an integrating circuit, a proportional circuit, and a derivative circuit. The integrating circuit includes a reset adjustment for varying a time constant thereof, the proportional circuit includes a gain adjustment for varying the gain thereof and the derivative circuit includes a rate adjustment for adjusting the rate of derivation of the signal. The gain adjustment comprises a photoresistor associated with a source of light which is provided with varying current corresponding to the signal to vary the resistance of the photoresistor and, thus, the gain value. The reset and rate adjustments may also comprise photoresistors with light sources or may be formed of field affect transistors each controlled by a circuit and remotely located potentiometer or variable voltage source.

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: An enthalpy measuring arrangement for measuring the heat content of a substance which may in the liquid phase, vapor phase or a mixed phase of liquid and vapor, comprises a first enthalpy calculating module for calculating the enthalpy of the substance when in a two-phase condition utilizing a plurality of discrete function blocks. The specific volumes of the overall mixture is calculated using a density transmitter which measures the density of the substance. Tables are utilized to obtain the specific volumes of the gas and vapor part of the substance on the basis of a measured temperature for the substance. These values are in turn used to obtain a quality value which is multiplied by a value representing the difference between the enthalpys of the vapor and liquid components of the substance to obtain the overall enthalpy of the mixture. Another module with a plurality of function blocks generates the enthalpy of the substance when it is superheated or entirely in the vapor phase.

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 sensor circuit method of operating a vortex shedding flow meter utilizes A.C. single cycle bursts to intermittently drive a sensor which changes its state with the vortex shedding frequency. The bursts are spaced in time by an amount larger than the burst duration.

Abstract: A fiber optic device senses the generation of vortices by measuring the torsional displacement of a bluff body mounted for rotation about its center of inertia within a fluid conduit. An internally toothed member is fixed to the outside of the fluid conduit, and an externally toothed member is fixed to the bluff body for rotation therewith and is in partial meshing relation to the externally toothed member. An optical fiber is entrained between the toothed members and has one end exposed to a light source and the opposite end connected to a detector which is operable to detect changes in the intensity of the light transmitted through the fiber. As the bluff body vibrates, the toothed members are displaced relative to one another causing changes in the radius of curvature of the segments of the optical fiber received between the teeth, thus changing the intensity of light transmitted through the fiber in proportion to the changes in the radius of curvature.

Abstract: A system is disclosed for increasing the main steam temperature in a boiler/turbine installation to the maximum level consistent with safe operation of the installation. The difference between the main steam temperature and a system parameter is determined and used as an index to adjust the main steam temperature set point upward or downward. The system parameter selected for comparison with the main steam temperature may be the allowable variance between the main steam temperature and the main steam temperature set point or may be a "safety margin" temperature selected so as to be below the maximum allowable temperature for the installation.

Abstract: A function generator producing an output signal varying in predetermined non-linear relationship to an input signal wherein the input signal addresses a programmable read-only memory (PROM) which is programmed to produce readout signals linearly proportional to selected values of the input signal and readout signals corresponding to the predetermined non-linear function of the input signal at said selected values and the output signal is derived by interpolation between the consecutive selected input signals which bracket the input signal.

Abstract: A device and method is disclosed which determines the presence and absence of a burner flame by injecting a pressure modulated signal into the burner which modulates a flame at a selected frequency. Light emitted from the flame is modulated at the same frequency. An optical sensor is provided for sensing the light amplitude modulation frequency and connected to a correlator circuit for correlating the light amplitude modulation signal with the pressure modulation signal. If the signals correlate, a flame is assumed to be present and a flame on signal generated. The pressure modulation signal can be discontinued periodically. If a corresponding discontinuation of the light amplitude modulation signal is sensed this is indicative of the continued presence of the flame whereas a continuation of the light amplitude modulation signal indicates a flame out condition.