Abstract: An automatic level control system and method provide continuous proportional control of an inlet valve when the level of material in a storage container is between low and high limits. The system includes a main feedback loop and a nested feedback loop to insure proper control of the inlet valve through which material is added to the storage container. The main feedback loop provides a control signal indicating the desired setting of the inlet valve, and the nested feedback loop provides a control signal indicating the actual position of the inlet valve so that the two control signals can be compared for use in accurately moving the inlet valve to the desired position. The main feedback loop includes a computer into which different density values can be input for accurately determining the amount of material in the container as indicated by a weight sensor.

Abstract: An automatic mixture control apparatus includes a micro-computer-based data acquisition and control device which responds in real time to flowmeter and densimeter signals to control water inlet and bulk cement valves so that a cement slurry is produced at the desired rate and density. The data acquisition and control device is programmed to provide means for computing desired positions for the valves and for computing corrections for the positions. A related automatic mixture control method is also disclosed.

Abstract: A filter for use with a signal which varies about a mean such as in a radioactive densometer, is provided and includes a microprocessor and timing clock for sampling the random variable over a specific time interval. The microprocessor utilizes a weighting factor which is used to determine a percentage of an average frequency of an initial sample of random signals or mean. Further, the microprocessor determines a percentage of an average frequency of a subsequent sample of random signals. Once determined, the two percentages are added together yielding a new frequency which the microprocessor then uses to decide if an actual change in state has occurred.

Abstract: An air preheater water jet apparatus is provided for cleaning fly ash, soot and the like from a rotating or stationary heat exchange basket on a air preheater used to improve the efficiency of a boiler in an electric utility generating plant. The air preheater cleaning apparatus includes a cleaning assembly with water jet nozzles, thereon, attached to a carriage which moves along a track, such as a channel beam, affixed radially above and adjacent to the air preheater basket. A drive assembly and an idler bracket assembly with a roller chain therebetween are disposed on the channel beam. The carriage assembly is attached to the roller chain and as the carriage is driven, the cleaning assembly is moved along the channel beam. Thus, when the basket, or the air preheater cleaning apparatus, is rotated and the carriage is moved inward, a circular path of the basket is cleaned.

Abstract: A data monitoring system includes a display unit for communicating with an operation that has characteristics which are to be monitored, a recording unit located remotely from the environment of the monitored operation, and a local area network interconnect circuit for connecting the display and recording units. The local area network circuit allows multiple display units to be connected to a single pair of electrical conductors. Each display unit has at least one dual microcomputer configuration interconnected by a shared dual port random access memory. A third microcomputer is located in the recording unit for communicating over the local area network circuit with one of the microcomputers in the display unit.