Showing papers on "Process variable published in 1988"

Pilot process variable study of coolside desulfurization

Abstract: The Coolside desulfurization process is a dry sorbent injection technology developed for retrofit SO/sub 2/ control in coal-fired utility power stations. The process is low in capital and space requirements since, in its ideal configuration, the existing ductwork and particulate collector are used as the SO/sub 2/-sorbent reaction spaces. It has been developed through laboratory and 1 MW-scale field tests using hydrated lime as the primary process sorbent by Conoco Coal Research Division, the research branch of Consolidation Coal Company. The field work showed promising results with observed SO/sub 2/ removal ranging up to 80%. In order to optimize the process performance through improved understanding of the process fundamentals, Conoco constructed and is operating a 0.15 MW pilot test unit. This paper describes the results of a process variable test program, a first series of tests made in the pilot unit, and the unit operability observed during the test work.

Anti-reset windup for controllers in selective control loops

Abstract: A tuning adjustment for a PI controller is disclosed which produces a desired response for a controlled variable in a selective control loop having an external reset feedback signal for anti-reset-windup protection. The desired control effect is evident in the time response of the controlled variables return to set point when a select switches signals and suddenly selects an output limited PI controller to control a process variable, and the selected controller assumes control of the process variable starting with its output at the limiting value. The tuning adjustment is implemented by combining the signal selected for controlling the process variable and a tuning factor for use as the reset feedback signal for the PI controller.

Process for the production of a preform by the PICVD process

Abstract: A process for the production of an optical fibre preform by the PICVD process, in which radiation emitted by the plasma in the region of one end of the coating zone is recorded and a parameter of the recorded radiation is adjusted to a desired target value with control of a process parameter affecting the axial position of the corresponding end of the deposited layers.

Method of and device for inspecting and/or controlling metallization processes

Abstract: A method for checking and/or controlling a metallization process in a galvanizing or chemical is based on the measurement of light scattered off or reflected from a surface portion being metallized. A deviation from a predetermined nominal value of the scattered or reflected light intensity serves for controlling at least one process parameter to neutralize the deviation.

Digital controller display

Abstract: A digital controller includes a microprocessor for receiving a signal indicating a process variable from a process and calculating a manipulated variable in accordance with a predetermined algorithm in order to cause the manipulated variable signal to follow a desired setpoint variable. An operation data output system delivers an output signal to the process which holds the operation output value from the microprocessor. The controller also has on an electronic indicator for displaying the process variable, the setpoint variable, and the manipulated variable, and a driver for receiving the process variable signal and the setpoint variable to drive the electronic indicator. The driver further receives the manipulated variable from the operation data output system for driving the electronic indicator, whereby the controller is capable of displaying the manipulated variable on the electronic indicator should the microprocessor fail.

Time-series data processing system for process variable in transient state of plant

Abstract: PURPOSE:To analyze the transient phenomenon of a process variable easily and efficiently by connecting a decentralized digital control system to a process computer by a fast communication line, and inputting process variable information on an information gathering period at a necessary period and storing it for a request period. CONSTITUTION:The decentralized digital control system 2 measures the process variable by a detector 4 at a necessary place in a plant, gathers and converts the information into an technical value at a constant period, and stores it in a memory 5. A controller 7 refers to a communication catalog 6 periodically to extract information and sends it by a communication device 8 through a line 3. The computer 1 stores the information in the necessary period in a memory 12 by a communication device 10 and a controller 11. The information storage is stopped for a necessary period after process variation, abnormality, and analysis request occurrence, and the information is stored and analyzed by using analytic software according to the purpose, so that the result is displayed on a display device 13 or printed out on a printer 14.

Method for regulating a process variable of an industrial process applied to two or more consumers that can be switched in or out, in particular for the pressure regulation of a burner or heating system

Abstract: In known methods, the large fluctuations of the process variable caused by cutting consumers in or out are corrected for by a comparison of setpoint and actual value and, depending on this, the generation of an closed-loop control signal acting on the process variable Large deviations between setpoint and actual value that are undesirable or impermissible can occur under certain circumstances In the method according to the invention, switching in or out of a consumer is detected, and a pulse-shaped control signal which is superimposed on the closed-loop control signal is generated depending on this Thus, no large deviations between setpoint and actual value are necessary to correct for large fluctuations of the process variable due to the cutting in or out The method can be used in regulating the pressure of a burner system or heating system

Estimation of the Process Parameter for High-Pressure (supercritical fluid) Carbon Dioxide Extraction of Natural Products

Abstract: The objectives of this work were to find a useful concept for the design of hig-pressure extraction (HPE) plants and to carry out a parameter analysis of various influences on construction and design. To evaluate the influence of each parameter on the process better, the parameters were subdivided into five groups. Experiments were made to determine the solubility and mass transfer of neutral products in CO2. These results were tested with models in order to establish the possibility of a mathematical description of HPE processes.

Process and arrangement for determining a process variable in the heat treatment of metal parts

Abstract: To determine the carbon concentration of metal parts during their heat treatment with mass transfer, an electrical resistance measurement is carried out on the metal part (1) using alternating current and is repeated at various frequencies. From the sequence of the selectively measured resistance values at the various frequencies, a carbon concentration profile is obtained as a function of the distance from a surface of the heat-treated metal part. After determination of the carbon concentration at the metal part surface, the average carbon concentration in successive layers is determined iteratively using a computerised evaluation facility (15, 20). If the carbon content is kept constant during the heat treatment, the temperature distribution in the metal layers can also be determined from the resistance distribution in the metal part.

Method for identifying process parameter

Abstract: PURPOSE:To apply control suitable for the fluctuation of a process, by estimating the variable and the constant of the process at every data sampling period, correcting estimated variable and constant of the process based on an error correction gain, etc., and performing identification after correcting an error dispersion. CONSTITUTION:A non-linear process model is found at a non-linear process model part 3, and a difference equation model is found by digitizing it with a difference equation model 4. Next, the difference equation model is converted to a linear equation with respect to desired variable and constant at every data sampling period at a linear equation model part 5. Afterwards, an estimate equation is found from the sizes of the variable and the constant desired to be estimated at an estimate equation deciding part 6. Following that, an estimate arithmetic processing is performed at a sequential maximum likelihood estimate arithmetic part 10, and a variable and constant coefficient matrix is calculated at a variable and constant coefficient matrix part 11, then, the variable and constant of the process is estimated. Next, an estimate value is formed at an estimate value calculation part 13, and an estimate value error is calculated from the estimate value and a measure value at an estimate error calculation part 14. And whether the estimate error value is converged or not is decided at an estimate error convergence deciding part 15, and the error dispersion is corrected at an error variance correction part 17, and fixing is continued when no convergence is obtained.